SLA Biomedical & Life Sciences Division Blog

Do Snake Venoms Evolve According to the Prey They Are Intended to Kill, Or Do Snakes Just Dial Up the Dosage or Concentration of Whatever Venom They Have to the Size of the Prey in their Sights?

Snake venoms are overwhelmingly composed  of dissolved protein  mixtures which typically exert their action on a victim in one of the following three ways, and sometimes in combination:

·        Hemotoxins. Depending on their mix of proteins, these can either cause the blood to clot precipitously, causing cardiovascular blockages (essentially heart attacks) in extreme cases, or alternatively, cause it to thin so quickly that the victim bleeds out.  This is one of the  modes of action of rattlesnake venoms.

 

·        Neurotoxins.  These disrupt either or both the voluntary and autonomic nervous system of the victim, rendering it incapable of escape, and in extreme cases, cause the victim to stop breathing or to convulse. This is the primary  mode of action of cobra venoms.

 

·         Tissue Necrotizers:  These basically break down the muscular and connective tissue at the site of the bite, and basically cause an ever expanding dead zone until the toxin is so diluted as to lose effect. Often the victim dies before this can happen. This is the mode of action of the fer-de-lance the most prominent perpetrator of poisonous snake bites in Latin America.

The popularity of proteomics and the wider availability of its instrumentation  leads to “venomics” & confirms evolutionary relationships & distinctions  among the many differing families  of poisonous snakes

 

Can you tell a venomous snake just by a chemical analysis of its venom?

The short, and historically most orthodox answer,  is, yes.

For most of the history of snake venom studies , the relatively small number of total analyses achieved indicated that most snakes tend to have signature venom protein mixes.

Now, given the widespread use of automated proteomics analyzers and advances in protein sequence informatics, much of this  old work is being confirmed with more  complete analyses of more venoms from more snakes and especially from differing families of snakes. Indeed, you can now search a variety of biomedical, chemical and pharmaceutical  databases under “Venomics” for on-point papers.

 And the new results can be extended to say that snakes that are in the same genus tend to have rather similar, if not always quite identical, cocktails of toxins.

Such variations as are found, are thought to be minor,  the results of random genetic drift, and to be incidental to the  study of  either the lineage, the  or day-to-day functioning of the snake.

There is  some thought that evolutionary relationships suggested by traditional morphological characters or modern genomics ,  can predict,  with reasonable certainty what venom toxins given families of snakes are likely to share, even before all their members are tested.

As a kind of real-world proof of the all-in-the-family nature  of protein toxins , consider that snake antivenoms (which work on biochemical recognition and disabling of venom proteins through binding them up)  work best when customized to the type of specific snake that does the biting. Such antitoxins are called monovalents, and are the treatment of choice whenever available.

But  given that maintaining a large and varied collection of monovalent antivenoms  is not always practical in areas where there are many possible different poisonous snakes which bite, some polyvalent vaccines have had to be developed which counteract, to some degree,  venoms from a variety of unrelated species.

Despite their polyvalent intent, their comparative effectiveness is positively correlated  with snakebites  that are evolutionarily related to the species from which the original pharmaceutical venom/vaccine was drawn.  In other words, antivenom that derives from a specific type of cobra,  is likely to work better with other persons bitten by somewhat different cobras, than it is to work on people bitten by rattlesnakes.

The prevalent theory is that the biosynthesis of toxins is likely to be highly conserved  over many generations and over differing populations of snake families  because their venom seems so central to the function of the snake, and that even incidental variations in toxins caused my random mutations could come at a cost to the snake in reduced prey killing capacity.

But  the dismissal of the significance of small differences in toxin blends within related snakes  is now being challenged,  and variations are being seen as having some meaningful function, and not just being blips in encoding that have no real life meaning to the snake.

Why have differing toxins within the same family of snakes? Couldn’t the snake just adjust the dosage to the size of the prey?

Differing types of snakes have differing quantities of venom available for hunting or defense, but certain general rules can predict among populations of the same snakes which will have more venom on average.

Generally, the older the snake of a given species is , the larger it is, and therefore the larger its storage and potential supply of venom for “envenomation, ”  when compared to younger and smaller snakes of the same species.

Furthermore female snakes generally have significantly more venom than males for two  readily  understood reasons: They are generally larger than males and have larger heads, and the head is where most of the venom production and storage is confined in all but a tiny handful of snake species.

But, it turns out that many adult snakes, whether large or small,  are actually thrifty in their use of venom.

They adjust the amount of venom to the size of their prey.  A mouse might get less venom per bite  than a gopher, for example.

Although as a general rule, given a choice between small and large prey , larger snakes will choose larger prey, and are willing to “spend the venom”  in order to get the larger meal.

The saw-scaled viper family and their venoms

A particularly  interesting comparison test of the venoms of four kinds of  saw-scaled vipers done by Barlow et al. (2009, cited below).

These four related viper species  are a genuine menace to public health in that they cause the majority of snakebite cases in North Africa and the adjacent Middle East.

 (The fact that some of them kill harmful vermin, may, of course be an offsetting factor, before deciding that they all should be wiped out indiscriminately.)

A comparison of the  electrophoretic separations of major toxin proteins  from the four different types of saw-scaled viper  showed that they were indeed, matching in the major protein bands,  something predictable owing to conventional thinking about the molecular evolution of snake venoms.

But there was a surprising amount of variation in the minor bands.

And this was also reflected in the fact that in the Middle East and in Northern Africa, saw scale viper antivenoms were markedly more effective against  Middle Eastern saw scale viper bites than they were against the bites of  the North African saw scale vipers that were presumed to be their evolutionarily closest relatives.

The drop off in effectiveness is notable in clinical terms and makes follow-up injections or IV drips of antivenom necessary more often in North Africa than they were in the Middle East.

A question arose:  Beyond any clinical significance, did these  variant protein toxins  have a purpose in the life of the snake?  Or, were they just the result of geographic isolation and random genetic drift?

Prey size vs. prey type: Which  plays a bigger role in the  evolution of venoms?

One competing theory of comparative venom toxicity  is that snakes within the same general family of snakes that prey on larger animals will eventually evolve   not only to produce more of the same general type of venom,  but also evolve higher, and therefore more potent concentrations of venom, with which to immobilize and kill their “big game.”

Its principal rival theory  is that differing prey  specialists within the same general family of snakes are more likely to require,  and eventually develop over succeeding generations venoms that gradually become more distinct, depending for success in killing prey, not so much on increasing the amount or the concentration of venom injected,   but rather on matching  the prey’s particular susceptibility to the venom.

Saw scale vipers represent a wonderful set of relatives upon which to test these competing outlooks.

Several types of saw scaled vipers have become small mammal specialists (usually eating rodents)  in terms of their prey.  Most of these are in the Middle East.

Others have a mixed diet of rodents and invertebrates.

(Most commonly in the Middle East and Africa, the invertebrates are various types of scorpions. )

Still others are almost exclusively scorpion feeders. These vipers are found only in North Africa.

It should be understood that even the biggest scorpions are but a fraction of the size and weight of the mice and rats typically consumed by either the rodent specialist,  or the mixed-diet-consuming saw scale  vipers.

Consequently “big game venom” should actually be more toxic to little game, because of its overall increased potency.

In other words, it may not be necessary to shoot a big-game venom cannon ball to kill a scorpion, but if it were to happen,  the cannon ball should surely be lethal to the scorpion.

Using ingenious methods, such as directly injecting carefully calibrated, matching fluid amounts of venom directly into  test scorpions from all four types of saw scale viper, and then seeing which venoms were, “ounce for ounce” more deadly, the team found something unexpected.

The “big game hunters”  of rats and mice, who would presumably need more toxicity to bring down their big game, actually  had venom that was notably less toxic to the small size game of scorpions, than the venom   of the mixed-bag-diet hunters.

And even more  intriguingly,   the mixed-bag-hunter venom was still less toxic to the scorpions than that of the specialized scorpion hunters.

The most toxic & effective venoms against the small game of scorpions, came from scorpion specialists, not from big-game or mixed-game specialists, who routinely had to knock down and kill bigger game.

In other words, the venom of North African scorpion specialists had become distinct enough through evolutionary adaptation to its prey, to make a difference in the life of its particular type of saw scale viper.

And maybe that distinction was now big enough to explain why Middle Eastern antivenom vaccines against North African saw scale vipers were seeing decreased efficiency.

Are the prey utterly without their own evolutionary defenses against specially  evolved snake venom?

This would seem to be the case, but in a number of settings, various ground squirrels, gophers and badgers, whose paths frequently intersect with predatory snakes like rattlers, seem to have grown immune to the local venom (see, for example Hayes, Lavin-Murcio & Kardong, 1995, cited below). This is also the case with some eels that live alongside sea snakes that hunt for eels (Heatwole & Pran, 1995).

Whether or not this leads to the evolutionary  alteration of the local snake venom to make if effective once again, has not yet been studied.

But in a particularly intriguing case, a poisonous sea snake that has become a fish egg eating specialists, and therefore has no need to immobilize and kill its prey (the eggs don’t run away and are not guarded by their parent fish) has actually evolved venom of greatly reduced toxicity, seeming to spare itself unnecessary toxin protein production (Li, Fry & Manjunatha Kini, 2005).

 

Tony Stankus [email protected] Life Sciences Librarian & Professor

University of Arkansas Libraries MULN 223 E

365 North McIIroy Avenue

Fayetteville, AR 72701-4002

Voice: 479-575-4031

Fax: 479-575-4592

 

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Prion proteins: How studies of yeast help us understand the assembly line manufacturing of beta-folding amyloid plaques strongly associated with Alzheimer’s Disease in humans.

Simpler  does not always mean “easier to understand: ”

Going down in size from our kind of complex cells to prions, thus far, the simplest & strangest biological agents of them all

 

As the scale of  matter that is considered to be alive, or at least, active in living systems and able to reproduce itself,  has gotten smaller over time, the newly discovered  and ever smaller units  have fewer and fewer components.

 

The questions arises: How small and how simple can they get?

 

For eukaryotes (that is the kind of cell we’re mostly made of ….as are most animals and many plants) you need a cell membrane or cell wall that contains the cytoplasm, and a variety of specialized organelles within it, most notably a nucleus within that cell, that has its own membrane,  and that contains multiple, separate  strands of nucleic acids, like DNA or RNA, and usually both.

 

All these  are necessary for the eukaryotic cells to function, through the production and metabolism of proteins, fats, and carbohydrates,  and especially are required for these  cells to reproduce themselves.

 

It  took us about 200 years after the microscopic discovery of eukaryotic cells to get much of a basic understanding of how they functioned, with the DNA/RNA/ protein synthesis  part  becoming clear only in the late 1950s.

 

For prokaryotes (and this includes most bacteria and archaea ) there are few if any organelles, and there really is no nucleus. The bacterial and archaeal cell contains only  a single loop of DNA, which can make RNA,  and together these nucleic acids  make the proteins, lipids and carbohydrates necessary for the unit as a whole to function. 

 

And, surprisingly,   this much simpler arrangement still also carries  all the DNA information necessary for this simpler  organism to reproduce.

 

We figured how bacteria really work only a little while later than we did the eukaryotes, because it was apparent early on that bacteria, in particular, could cause diseases.

 

Furthermore, some bacteria, particularly E-coli, turned out to be great tools for understanding genetics and the work of DNA.  Their very simplicity made them ideal for experimental purposes. A check of WorldCat discloses literally hundreds of books and dissertations on E. coli even now. (See Glass, 1982; Vaillancourt, 2003, & Zimmer, 2008, cited below by way of example.)

 

Viruses are even more stripped down than bacteria and archaea. They can be described pretty much as nucleic acids protected by a protein coat. No membranes. No cytoplasm. No organelles. No nucleus. No carbohydrates. Very rarely, some have lipids as a secondary  protective coat, but most have none.

 

The overwhelming majority of viruses then, are just DNA or RNA and their protective protein coat. That coat  also enables them latch onto and pierce the membranes of  bacteria, archaea, or eukaryotes.

 

Once inside the cell, viruses  hijack the cellular machinery of their unwitting hosts in order to function and reproduce through simply replicating their own  DNA or RNA and those proteins coats, instead of what is needed by the cell.

 

It took only about a decade longer to figure to figure this out, largely because electron microscopy was vastly improved by this time and the need to make anti-viral vaccines and drugs had accelerated research.

 

And curiously the nature of a disease that infected a then  important cash crop, called the Tobacco Mosaic Virus, proved almost as important. TMV had whole books written about it, ( see Scholthof, Shaw & Zaitlain, 1999, cited below by way of example) , and took on a life of its own as a model organism.

 

In any case, for the bulk of the twentieth century, it was thought that viruses were about as small and simple as biology could get.

 

But while there were early inklings that there could be something smaller that mattered to biology, it was not really until  1982 that someone could isolate that something smaller and give it a name.

 

That someone was Stanley Prusiner, and that name was “prion. “ Ultimately this got Prusiner the 1992 Nobel Prize, and prions too, have gotten their own whole books.

 

Prions  are even simpler than viruses.  They have no DNA or RNA. They have only misfolded proteins,  yet somehow they manage to reproduce themselves.

 

This would seem to be a kind of magic trick except for the fact that prions seems to be the cause of obscure but invariably fatal human neurological diseases like Creutzfeld-Jacob,  as well that of important agricultural diseases like scrapie in sheep and goats and mad cow disease.

 

This latter obvious affects  cows, and sometimes humans who eat the neurological parts of  cows (largely portions of their brains, spinal cords, or muscle tissue with extensive innervation.)  

 

 Ironically, while these agricultural diseases had been well known but not well understood back into the 1700s, the fact that human infections could be caused by what were later shown by workers like Prusiner   to be prions,  had actually won the Nobel Prize for another scientist Carleton Gajdusek much earlier,  back in 1976.

 

Gajdusek noted that certain South Sea island cannibals came down with the bizarre and fatal illness of kuru, through the ritualized eating of the brains of deceased relatives who had been previously  infected with this mysterious agent we now know as prions.

 

But many  questions remained. How do prions form and reproduce themselves? Are all proteins capable on some level of turning into prions?  Do prions turn into something else. Are they involved in other diseases?

 

While the mad cow disease panic of the late 1990s caused quite an impetus to prion research, perhaps no greater reinforcement has come to pass since the discovery that those misfolded prion proteins  are very similar to  another disease which seems to involved misfolded proteins: Alzheimer’s.

 

Alzheimer’s Disease involves , within the brain, tangles of fibrils or sheets of proteins that have today become best known by their structural classification as beta-folded amyloid proteins.

 

 Have we found a simple model system to understand better the conditions that turn proteins into prions?

 

Just as we have used smaller and simpler biological systems to better understand general biological phenomena, much as we used the bacterium E.  coli to study general genetics or TMV to  study  general virology, it turns out that the simple microorganisms, the yeasts,  have an abundance of proteins, some of which seem to have the  tendency to become prionogenic.

 

 In other words, they tend to form disordered beta- sheets, that remarkably tend to be passed on between different generations of yeast.

 

The type of yeast used had a relatively simple form of reproduction, called budding,

 

In budding,  daughter yeast cells grow in interior dents within the parent yeast membrane, and when the daughter compartment  gets large enough, it breaks off without damaging the parent yeast cell, and assume an independent existence.

 

And fortunately for the yeast, and for the researchers who needed a stable, non-infective source of prions and a model system to study their manufacture, these beta-sheets do not seem to harm the yeast, and in fact, have some beneficial effect in terms of the yeast’s own structure.

 

Over time, a variety of clearly prionogenic proteins ( among those most commonly mentioned are those labeled as Sup35p, Ure2p, and Rnq1p ) have popped up in these yeasts, and yet,  few common factors could be detected among them. 

 

 

Among those few facts was that each of these prionogenic proteins resisted a chemical treatment called denaturing, which, while primarily a lab procedure, is indicative of extra  survival capability.  

 

In addition, all these prionogenic proteins had structural sequences that were rich in either glutamines or asparagines.

 

Building on some earlier pioneering work on genomic and proteomic screening, as well as some studies of protein structures using magnetic resonance imaging,  Alberti et al. (2009, cited below) developed a systematic screening procedure for sorting out which yeast proteins are prionogenic, and then analyzed these to find commonalities. Fowler & Kennedy (2009, cited below) provide us with a very helpful summary of how this process worked

 

Albert et al.  used a 3-way screening procedure   involving 100 different candidate proteins.

 

Candidate prionogenic proteins had to show that they formed aggregates in living yeast that were supplied with all the usual protein precursors in culture that would enable them easily to manufacture proteins, (and therefore beta sheets) ,  in  abundance . 69 out of 100 candidates passed this test.

 

Candidate prionogenic proteins had to form aggregates in  relatively protein deprived in-vitro tests.  Despite the lack of a healthy protein assembly line in operation, 50 of the 69 remaining  candidates passed this test, scavenging enough material to form aggregates in three days.

 

These successful prionogenic proteins all shared that highly indicative denaturing resistance factor.

 

Finally candidate prionogenic proteins had to work well  with another protein called Hsp104p, which was important to the reproductive budding process, so that enough of the prionogenic proteins reliably transferred into each bud, so as to perpetuate the prions and their resulting beta sheets in succeeding generations of yeast.

 

In other words, the prions had the capacity to assemble themselves not only  in parents  but also in their daughters on a continuous basis.

 

19 candidate prionogenic proteins passed this final test.

 

What was most surprising about this group of finalists ?  The fact that they were resistant to denaturing was reassuring but not the most unexpected finding.

 

That was that protein sequences rich in asparagines were dramatically more likely to be prionogenic than were those rich in glutamine.

 

This may seem like a small triumph, but it is a triumph of figuring out what raw materials seem to work best in a model assembly line from which we wish to extrapolate the more complicated and still mysterious  beta-sheet amyloid-making processes going on in our aging brains.

 

 

Tony Stankus [email protected]  Life Sciences Librarian & Professor

University of Arkansas Libraries MULN 223 East

365 North McIlroy Avenue North

Fayetteville AR 72701-4002

Voice: 4790409-0021

Fax: 479-575-4592

 

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Chae, Y. K., Cho, K. S., & Chun, W. (2002). A prionogenic peptide derived from Sup35 can force the whole GST fusion protein to show amyloid characteristics. Protein and Peptide Letters, 9(4), 315-321.

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THE SAND FLY & LEISHMANIASIS: IS AN UNFAMILIAR INSECT VECTOR & A NEGLECTED INFECTIOUS DISEASE COMING TO A HOME NEAR YOU WITH A RETURNING VETERAN, RECENT IMMIGRANT, OR VACATIONING WORLD TRAVELER?

The More Familiar Mosquito & the Less Familiar Sand Fly Operate as Disease Vectors Using Similar Strategies

Few people in the modern western world, especially  in its northern latitudes,  have heard of sand flies or Leishmaniasis (named after a Scottish medical researcher,  William Leishman), but many more are likely to become aware of both of them, owing to some changes in the world’s medical geography and epidemiology.

Fortunately, by applying some of their understanding of the mosquito’s propensity for  transmittal of malaria, one can gain a basic insight into why and how sand flies can transmit Leishmaniasis.

Most scientifically-literate people today understand that malaria is a disease carried by infected female mosquitoes,  and transmitted to biting victims during the mosquito’s  biting  of humans and other warm-blooded animals, in their quest for a blood meal.

Female mosquitoes  need that  blood meal in order to have more vigorous eggs with protein supplies that are adequate for viability.

 When setting up the bite,  the mosquitoes initially  transmit some enzymes that keep the victim’s blood flow going, so that the wound does not close off, clot,  and prematurely deprive them of  that necessary blood.

Coincidentally, during the biting and enzyme injection prior to the blood withdrawal, the mosquitoes also transfer any malarial protozoan parasites they have contracted on their travels from blood source to blood source.  

Mosquitoes can certainly live and reproduce without the parasites, and not all mosquitoes are even capable of carrying these parasites.

But the more animals and humans that are around to be bitten that already have malarial parasites in their blood stream, the more likely it is that other animals and humans without the parasites, will get them once the mosquito bites the “wrong” victim before he gets to the uninfected victim, and bites him or her.

Sand Flies

Like the mosquitoes,  not all sand flies can carry the disease of Leishmaniasis, and about a third of the known species  of sand flies do not.

But those sand flies that can carry  Lesihmaniasis are almost as ubiquitous as malaria-carrying mosquitoes.

Since sand flies are only about a third as large as mospquitoes, many of their victims do not initially notice that they have been bitten.

Many sites where humans have been bitten show no signs of a wheal such as are seen with mosquito bites, and those lesions that do develop often take weeks or months, although some people have an essentially allergic blistering reaction that is more obvious.

Both   mosquitoes and sand flies favor hotter climates, although the sand fly does not need the abundance of water most commonly associated with mosquitoes and their larvae.

The primary areas of sand fly infestation in the Old World are Central Asia (including especially Iraq, Iran, & Afghanistan), portions of South East Asia, and Northern Africa.

 However, Southern Europe, including Italy, Southern France, Spain, Portugal, and Greece, are seeing a resurgence of sand flies and Leishmaniasis, and even Northern & Central Europeans are coming down with it, after decades and indeed, sometimes centuries without cases in a given district.  

The variety of sand flies that carry Leishmaniasis in the Old World are from the subfamily called the Phlebotominae.

Both of the Americas have sand flies, although Latin America, and especially Brazil,  has the greatest concentration of both vectors and Leishmaniasis by far.

The variety of sand flies that carry Leishmaniasis in the New World are from the subfamily Lutzomyia.

The Varieties of Leishmaniasis

Despite the differences of insect variety and even species differences in the particular parasites, the major types, signs and symptoms  of Leishmaniasis disease are essentially the same in both Hemispheres.

The most common type is cutaneous Leischmaniasis. About 1.5 million new cases are estimated worldwide each year of this type, and about 12 millions cases seem recurrent or chronic.

The typical manifestation of this disease are bulbous swelling and sometimes subsequent collapse and disfiguring erosion of the skin, much as seen in leprosy. 

The lesions can look ghastly but many victims report that they are relatively painless, and even without medical treatment, a substantial portion of them resolve over the course of some months. (The painlessness of many cases is hypothesized to be owing to a mild neurotoxic effect of the sand fly salivary enzymes.)

Those that do not resolve typically have  two follow-on courses.

The most common, and even more disfiguring sequelae or variant is muco-cutaneous  Leishmaniasis. Here the mouth and nose become bulbous or cratered and less reversibly disfigured. Victims often become social pariah.

But by far the most serious type (and it is not clear that this must be preceded by the cutaneous type in many cases) is called visceral Lesihmaniasis.  Unlike cutaneous and even muco-cutaneous Leishmaniasis, this type is very often fatal in the half a million cases that start anew each year.

 

Visceral Leishmaniasis is characterized by the swelling of organs under the the skin and massive bloating of body parts, particularly the liver and the spleen. Internal bleeding and multi-organ system failure are the proximate causes of death.

The theory of why some patients develop the cutaneous or muco-cutaneous forms while others develop the far more serious visceral type, tends to revolve around the types and amounts of very potent blood-clot busting salivary gland-produced enzyme, maxadilan, that are found in the particular species of sand fly that does the biting.

It seems that those species with the most maxadilan, or with the maxadilan molecular conformations that are the most potent, disproportionately cause the visceral type, while those with less maxadilan or with maxadilan of a milder conformation, seem to cause the cutaneous and muco-cutaneous types.

A curious connection has been found between areas of the world where aluminum ions are abundant in the soils and water, and either the sand flies or the victims, an increased incidence or severity of Leishmaniasis, but this is, as yet, a side show compared to other lines of investigation.

Prevention and Chemotherapy of Leishmaniasis

Much as is the case with malaria, an ounce of prevention of sand fly prevention  is worth more than a pound of Leishmaniasis cure.

Owing to current military deployments today, the US Army and Marine Corps are perhaps the most aggressive researchers and practitioners of sand fly exposure reduction today. (see Vickery et al., 2008, cited below)

The most common Lesihmaniasis preventatives are the liberal use of bodily applications of DEET, and wearing clothing that covers as much of the body as the usually intense heat of the climate allows for.

Netting, which must be as much as 3x as fine in mesh, and treated with insecticide, has shown a good deal of efficiency.

Fortunately, sand flies have not developed as many cases of resistance to insecticides as have mosquitoes and a  relatively wide assortment can still be sprayed to good effect.

Now, there is a great deal of interest in identifying sand fly pheromones and using them to trap the sand flies, keeping them out of homes and tents altogether.

The news has not been as good with drugs after infection.

Some critics suggests that this is because the overwhelming proportion of Lesihmaniasis sufferers are desperately poor individuals in Third World countries, who are unlikely to be able to repay the drug discovery companies for the cost of developing new and better drugs.

Nonetheless, new drugs do come out intermittently, when governments provide incentives to investigate and manufacture anti-Leishmanials under “orphan drug” incentives.

Traditionally, the  most commonly used  drugs involve antimony-containing compounds. They require admission to a clinic for safe administration, are potentially toxic, expensive and have begun to lose their effectiveness on some subtypes of Leishmaniasis.

The antibiotic amphotericin has become a second line choice, and its cost has come down. Nonetheless, it is still generally administered by IVs performed in clinics, making it still rather expensive for patients who must stop work and travel many miles, often over days.

Curiously, the particular effectiveness of amphotericin for Lesihmaniasis was discovered in patients with AIDS and opportunistic bacterial  infections who coincidentally also had Leishmaniasis.

It has likewise proved useful for those IV drug addicts who contract Leishmaniasis through sharing needles.  

Milotefosine is a follow-on drug that has received World Health Organization backing, and is taken orally. Its cost is yet even more reasonable, but it too has run into some resistance problems.

There is an acceleration of interest and research in developing vaccines, particularly those that short-circuit the salivary proteins whose enzymes keep the skin’s blood flow from clotting so that the sand fly can obtain its blood meal before it clots.

The process by which salivary maxadilan proteins are synthesized in the sand fly and its mechanism of dispersal in its victim are increasingly well understood, and targeting these processes on a proteomic or transcriptomic scale provides  hope for the future.

Will Leishmaniasis become prevalent again in the Northern latitudes of the economically advanced world, for example, in the US?

A disproportionate number of cases of Leishmaniasis cases in Southern and Central Europe seem to involve natives who have returned from vacationing  in Lesihmaniacal endemic hot zones, as well as the influx of recent immigrants from those areas.

Livestock, and companion animals, particularly dogs, also seem to be reservoirs of the parasites.

Once again, infected people or animals, provide a home for the parasite, and local sand flies can themselves become infected by “foreign Leishmaniasis” parasites   through biting an infected person, and then pass it on to uninfected individuals through subsequent bites.

In the US, although there has always been a small number of Leishmaniasis cases in the Mid-South (e.g. Texas, Arkansas, Louisiana), a spike has been predicted owing to the number of veterans returning home form service in Iraq and Afghanistan. 

1300 US soldiers and marines have already contracted Leishmaniasis in these countries and it cannot always be detected or treated before these troops return home.

However, in one of the most intriguing studies (Claborn et al., 2008, cited below) it was determined that between two forts where many soldiers return from tours of duty in Iraq and Afghanistan, one had an environment that was conducive to sand flies, while the other one did not.

Fort Bragg in North Carolina is surrounded by cultivated pine forest, and well-plowed farms. While the heat there is sufficient to sustain a significant sand fly population, these two  types of ground cover do not.

By contrast, Fort Campbell in Kentucky is  characterized by deciduous forests and prairie land, which are not only hot enough  to sustain a sand fly population, but which both have the right vegetation and ground cover to help sand flies thrive.

Here’s hoping that biomedical librarians everywhere become increasingly proficient in the use of the first weapon against Leishmaniasis, credible scientific and clinical information.

Tony Stankus [email protected] Life Sciences Librarian & Professor

University of Arkansas Libraries MULN 322 E

365 North McIlroy Avenue

FayettevilleAR 72701-4002

Voice: 479-409-0021

Fax: 479-575-4592

 

Alvar, J. &  Jimenez, M. (1994). Could infected drug-users be potential Leishmania infantum reservoirs? AIDS, 8, 854.

Alvar, J., Yactayo, & Bern, C. (2006). Leishmaniasis and poverty. Trends in Parasitology, 22, 552-7.

Andrade BB, de Oliveira CI, Brodskyn, C. , Barral, A., et al. (2007). Role of sand fly saliva in human and experimental Leishmaniasis: Current insights.  Scand J Immunol. 66, (2-3), 122-7.

 Bates PA. Transmission of Leishmania metacyclic promastigotes by phlebotomine sand flies.  (2007).  Int J Parasitol. 37(10):1097-106.

Bates, P. A. (2008). Leishmania sand fly interaction: Progress and challenges. Current Opinion in Microbiology, 11(4), 340-344.

Champagne, D.E. (2005). Antihemostatic molecules from saliva of blood-feeding arthropods. Pathophysiology of Haemostasis & Thrombosis, 34 (4-5), 221-7.

Claborn, D., Masuoka, P., Morrow, M. & Keep, L. (2008). Habitat analysis of North American sand flies near veterans returning from Leishmaniasis-endemic war zones. International Journal of Health Geographics, 7,  article number 65.

Cortes, S., Afonso, M.O., Alves-Pires, C. & Campino, L. (2007). Stray dogs and Leishmaniasis in urban areas. Emerging Infectious Diseases, 13, 1431-2.

Croft, S.L., Sundar, S., Fairlamb, AH. 2006. Drug resistance in Leishmaniasis. Clinical Mircrobiological Reviews,  19, 111-6.

Dujardin JC, FAU - Campino, L., Campino L, Canavate, C., Dedet, J., et al. (2008). Spread of vector-borne diseases and neglect of Leishmaniasis, Europe.  Emerg Infect Dis. 14, (7):1013-8.

Gomes, R., Teixeira, C., Teixeira, M.J., et al. (2008). Immunity to a salivary protein of a sand fly vector protects against the fatal outcomes of visceral Leishmaniasis in a hamster model. Proceedings of the National Academy of Sciences, 195, (22), 7845-7850.

Hamilton JG.  (2008). Sand fly pheromones: Their biology and potential for use in control programs. Parasite 15(3):252-6.

 Joshi A, FAU - Narain, J. P., Narain JP,  Prasittisuk, C., Bhatia, R., et al. (2008). Can visceral Leishmaniasis be eliminated from Asia? J Vector Borne Dis. 45, (2):105-11.

 Kassi M, FAU - Kasi, P. M., Kasi PM, FAU - Marri, S. M., Marri SM, FAU - Tareen, I., et al. 2008. Vector control in cutaneous leishmaniasis of the old world: A review of literature.  Dermatol Online J. 14, (6):1.

Kedzierski L, Zhu, Y., Zhu Y, Handman, E., & Handman E. (2006).  Leishmania vaccines: Progress and problems.  Parasitology 133 Suppl.,  S87-112.

 Khatami A, FAU - Firooz, A., Firooz A, Gorouhi, F., Gorouhi F, Dowlati, Y., et al. Treatment of acute old world cutaneous Leishmaniasis: A systematic review of the randomized controlled trials.  J Am Acad Dermatol. 57, (2):335.e1-29.

Kumari, S., Kumar, A., Samant, M. et al. (2008). Proteomic approaches for discovery and new targets for vaccine and therapeutics against visceral Lesihmaniasis. Proteomics: Clinical Applications, 2, (3), 372-386.

Lerner EA, Iuga, A. O., Iuga AO, & Reddy VB. 2007. Maxadilan, a PAC1 receptor agonist from sand flies. Peptides 28, (9):1651-4.

Lines, J. Chikununya in Italy: Globalisation is to blame, not climate change. BMJ, 335, 576.

Maingnon, R., Khela, A., Sampson, C. et al. (2008). Aluminum: A natural adjuvant in Leishmania transmission via sand flies? Transactions of the Royal Societyof Tropical Medicine & Hygiene, 102 (11), 1140-2.

Malik, A.N.J., John, L. Bryceson, A.D.M. & Lockwood, D.N.J. (206). Changing pattern of visceral leishmaniasis, UK, 1985-2004.  Emerging Infectious Disease, 12, 1257-9.

Milon, G. (2008). Leishmania parasites: Could we consider them as living organisms per se? Microbes and Infection, 10(9), 1077-1081.

Oliveira, LF., Jochim, R.C., Valenzuela, J.G. et al. 2009. Sand flies, Leishmania, and transcriptome-borne solutions. Parasitology International, 58, (1), 1-5.

Prates, D.B.,  Santos, L.D., Miranda, J.C. et al. (2008). Changes in the amounts of total salivary gland proteins of Lutomyia longipalpis (Diptera: Psychodidae) according to age and diet. Journal of Medical Entomology, 45, (3), 409-413.

Rando, D. G., Avery, M. A., Tekwani, B. L., Khan, S. I., & Ferreira, E. I. (2008). Antileishmanial activity screening of 5-nitro-2-heterocyclic benzylidene hydrazides. Bioorganic & Medicinal Chemistry, 16(14), 6724-6731.

Ready, P. D. (2008). Leishmaniasis emergence and climate change. Revue Scientifique et Technique-Office International Des Epizooties, 27, (2), 399-412.

Reddy VB, FAU - Li, Y., Li Y, & Lerner EA. (2008). Maxadilan, the PAC1 receptor, and leishmaniasis.  J Mol Neurosci.,  36(1-3):241-4.

 Reithinger R, FAU - Dujardin, J., Dujardin JC, FAU - Louzir, H., Louzir H, FAU - Pirmez, C., et al. (2007). Cutaneous leishmaniasis.  Lancet Infect Dis., 7, (9), 581-96.

Valenzuela, J.G., Garfield, M., Rowton,  E.D. & Pham, V.M. (2004). Identification of the most abundantly secreted proteins from the salivary glands of the sand fly, Lutzomyia longipalpis, vector of Leishmania chagasi. Journal of Experimental Biology, 207, (21), 3717-3729.

Vickery, J.P., Tribble, D.R., Putnam, S.D., McGraw, T., Sanders, J.W., Armstrong, A.W., & Riddle, M.S. (2008). Factors associated with the use of protective measures against vector-borne diseases among troops deployed to Iraq and Afghanistan. Military Medicine, 173, (11), 1060-1067.

Volf, P., Hostomska, J., & Rohousova, I. (2008). Molecular crosstalks in Leishmania-sand-fly-host relationships. Parasite, 15(3), 237-243.

Wheat, W. H., Pauken, K. E., Morris, R. V., & Titus, R. G. (2008). Lutzomyia longipalpis salivary peptide maxadilan alters murine dendritic cell expression of CD80/86, CCR7, and cytokine secretion and reprograms dendritic cell-mediated cytokine release from cultures containing allogeneic T cells. Journal of Immunology, 180, (12), 8286-8298.

What is Regenerative Medicine? And What Will an Easing Of Restrictions on Embryonic Stem Cell Research Mean for this Field?

On March 9, 2009, President Obama lifted some sanctions initially imposed during the George W. Bush presidency on the study and use of human embryonic stem cells, a development of great importance for the new field of regenerative medicine.

 

 

 Regenerative   medicine today largely focuses on using cultured stem cells to replace adult specialized cells that are no longer operating well,  or operating at all.

 

 

The causes for the cellular malfunction or absence may be damage from  infectious diseases or trauma, collateral damage from tumor removal,  x-ray or chemotherapy treatments, as well as inherited diseases.

 

But most often   the need for cell replacement appears to be age-related.

 

Why do Cells Need to Be Replaced?

 

There is overwhelming evidence that specialized cells in adults lose much of   their ability to divide into health functioning cells with time.

 

Yet transplanting wholly mature and specialized cells that perform the same function as the adult cells that are failing in an organ or body part has been only marginally successful to date.

 

 

Immunological rejection and the fact that the transplanted older cellular  materials may themselves senesce, has often lead to rather short-terms restorative gains, if there are any gains at all.

 

The transplanted cells undergo only so many cell cycles of mitosis and then shut down.

 

 

Why are Stem Cells Good Candidates as Replacement Cells?

 

 

Stem cells share a property with many cancer cells. They can multiply forever, given the right environment and nutrients. In a sense, they are a self-perpetuating source of raw material for eventual cell replacement therapies.

Just as importantly,  stem cells have the ability, with the right prompting,  to transform themselves into specialized cells that can be transplanted.

 

 

 

 

The theory is that they will remain vital longer than do the usually  transplanted adult cells and tissues, and sometimes they do not provoke immunological rejection as soon or as extensively. 

 

The union of these two abilities basically means that, if all things go well, the regenerative physician-scientist has a kind of cellular clay deposit that replenishes itself and that clay can be spun and fired into a wide variety of specialized pots and vases, that subsequently hold up well.

 

 

Are All Stem Cells The Same?

 

 

There are two basic types of stem cells.

 

 

 

 

By far, the most promising to date have been human embryonic stem cells. These show the greatest flexibility in what kinds of cells and tissue they can be made to become in the lab.

 

 

These cells are obtained, as their name suggests,  from donated fertilized human embryos (usually “surplus” embryos that the mother-to-be now feels no need for keeping around because  she has already had a successful pregnancy or pregnancies).

 

 

 

 

These intact embryos  are sacrificed, by being torn apart,  at an early stage of their development, when the cellular components retain  the essential quality of being unspecialized or more technically “undifferentiated.” 

 

 

 

 

The now separated embryonic cells are plated onto petri dishes, where,  with the right growth medium, they thrive, until they are directed to develop into the more specialized cells that are required.

 

 

 

 

However, there are also adult stem cells. These have been derived from bone marrow, liver lobes, fat deposits, skin, umbilcal cords, and other tissues.

 

 

 

 

A key difference in their processing is that   in many instances they have to have their  “inflexible” adult specialization knocked out of them through switching off some of their regulatory genes.

 

 

 

 

In  other words, they have to lose the ability to do certain highly specialized tasks that are “used to doing”  in order to be retrained.

 

 

 

 

In return for this, they assume a child-like plasticity to grow in petri dishes with much the same vigor as do the embryonic stem cells, and after a time, they can be re-programmed into the cells that are needed for a particular patient’s replacement needs.

 

 

 

 

Reprogrammed adult stem cells actually have the possibility of being derived from the very patient who needs the cell replacement, meaning that they have the potential to have almost zero chance of being rejected.

 

 

 

 

What Obstacles Need to Be Overcome in Order for Stem Cell Research to Fulfill its Clinical Promise?

 

 

 

 

There is no getting around the fact that many people, even those who are scientifically very well-informed, feel that destroying human embryos is destroying human life, and are therefore opposed to this line of research on moral grounds.

 

 

 

 

Those who disagree with that argument say that the embryos would  likely be destroyed anyway, so that there is no point in letting them go to waste.

The counterpoint to that argument is that a market will develop for producing human embryos directly for embryonic stem cell research, and support for the idea and underlying cell culture technology of cloning humans embryos will be accelerated.

 

 

 

 

Apart from the moral arguments, there  is   an unfortunate, and  occasionally observed tendency of some introduced embryonic stem cells to form tumors rather than healthy functioning replacement tissues, and as yet this cannot be predicted or controlled.

 

 

Some of the most intensive work today is focused on characterizing markers (usually cell surface proteins)  for healthy versus suspect stem cells, and for identifying subpopulations of stem cells that seem more promising than others.

 

 

 

 

Because, without  marker screening,  the embryonic stem cell cure could be as bad or worse than the disease.

 

 

 

Finally, two essential stem cell and tissue engineering  technologies need to be greatly expanded.

 

 

 

 

The first is the enhanced tailoring of the chemical,  physical and even dynamical  environments (petri dishes  shaken or not shaken, rotated or not rotated, inverted or right-side-up, with structural scaffolds or without them) of the undifferentiated cell cultures, so they can be induced to be exactly the right kinds of specialized cells.

 

 

 

 

There are conceivably hundreds of different specialized cells   that  are needed, but not yet hundreds of surefire ways of making them, to the exclusion of other cell types.

 

 

 

Second, even once the right types of cell are arrived at in pure culture, how are they to be stored before being administered, and in what medium are they to be administered?

 

 

 

Right now, many stem cells are apparently being frozen for storage, but it is not clear that this does not sometimes destroy or alter the functionality of some of the stem cells after thawing.

 

 

 

Means of administration of stem cells include the development of solutions that will not kill either the stem cells or the tissues surround the site of injection.

 

 

 

This is a serious consideration because different sites in the body have subtly different biochemical pH balances,  ionic concentrations, and mechanical pressures involved. 

 

 

 

Likewise, time-release gels or sponge-like matrices are being developed so that the cells are released more gradually, or so that they will not be attacked by adverse conditions on site before they can become established.

 

 

 

What Are The Types Of Condition Or Body Parts That Are Under The Most Study?

 

 

 

The list of target diseases is growing. By far the greatest level of research has been in areas of neuroregeneration, for conditions like Parkinson’s disease and spinal cord injury.

 

 

 

Coming in at something like second place is diabetes research, followed by bone and joint work, especially cartilage repair.

 

 

 

Work on eye diseases and the kidney have been less common, but are increasing.

 

 

 

But the greatest surge in recent months has been in revascularization of damaged heart tissue and cardiac vessels.

 

 

 

More diseases and organ systems are likely to be targeted for a stem cell program, given that some restrictions that have limited the embryonic stem cell side have been swept aside.

 

 

 

Progress in basic understanding and prototypical storage and delivery systems will accelerate.

 

 

 

When will actual “cures” be had?

 

 

 

The best guess is somewhere in the 10-15 year range.

 

 

 

Tony Stankus [email protected] Life Sciences Librarian & Professor

University of Arkansas Libraries MULN 223 E

365 North McIlroy Avenue

Fayetteville, AR 72701-4002

Voice: 479-575-4031

Fax: 479-575-4592

 

 

 

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Habib, M., Caspi, O., & Gepstein, L. (2008). Human embryonic stem cells for cardiomyogenesis. Journal of Molecular and Cellular Cardiology, 45(4), 462-474.

Hare, J. M., & Chaparro, S. V. (2008). Cardiac regeneration and stem cell therapy. Current Opinion in Organ Transplantation, 13(5), 536-542.

Harris, D. T. (2008). Cord blood stem cells: A review of potential neurological applications. Stem Cell Reviews, 4(4), 269-274.

Hirst, A. R., Escuder, B., Miravet, J. F., & Smith, D. K. (2008). High-tech applications of self-assembling supramolecular nanostructured gel-phase materials: From regenerative medicine to electronic devices. Angewandte Chemie (International Ed.in English), 47(42), 8002-8018.

Hiyama, A., Mochida, J., & Sakai, D. (2008). Stem cell applications in intervertebral disc repair. Cellular and Molecular Biology (Noisy-Le-Grand, France), 54(1), 24-32.

Hoffmann, W. (2008). Regeneration of the gastric mucosa and its glands from stem cells. Current Medicinal Chemistry, 15(29), 3133-3144.

Hopkins, C., Li, J., Rae, F., & Little, M. H. (2009). Stem cell options for kidney disease. The Journal of Pathology, 217(2), 265-281.

Huang, N. F., & Li, S. (2008). Mesenchymal stem cells for vascular regeneration. Regenerative Medicine, 3(6), 877-892.

Kandel, R., Roberts, S., & Urban, J. P. (2008). Tissue engineering and the intervertebral disc: The challenges. European Spine Journal, 17 Suppl 4, 480-491.

Katoh, M. (2008). WNT signaling in stem cell biology and regenerative medicine. Current Drug Targets, 9(7), 565-570.

Khoo, C. P., Pozzilli, P., & Alison, M. R. (2008). Endothelial progenitor cells and their potential therapeutic applications. Regenerative Medicine, 3(6), 863-876.

Lederer, C. W., & Santama, N. (2008). Neural stem cells: Mechanisms of fate specification and nuclear reprogramming in regenerative medicine. Biotechnology Journal, 3(12), 1521-1538.

Leucht, P., Minear, S., Ten Berge, D., Nusse, R., & Helms, J. A. (2008). Translating insights from development into regenerative medicine: The function of  WNTs in bone biology. Seminars in Cell & Developmental Biology, 19(5), 434-443.

Lorenzini, S., Gitto, S., Grandini, E., Andreone, P., & Bernardi, M. (2008). Stem cells for end stage liver disease: How far have we got? World Journal of Gastroenterology : WJG, 14(29), 4593-4599.

Luong, M. X., Smith, K. P., & Stein, G. S. (2008). Human embryonic stem cell registries: Value, challenges and opportunities. Journal of Cellular Biochemistry, 105(3), 625-632.

Matzuk, M. M., & Lamb, D. J. (2008). The biology of infertility: Research advances and clinical challenges. Nature Medicine, 14(11), 1197-1213.

Muneoka, K., Allan, C. H., Yang, X., Lee, J., & Han, M. (2008). Mammalian regeneration and regenerative medicine. Birth Defects Research.Part C, Embryo Today : Reviews, 84(4), 265-280.

Muotri, A. R. (2009). Modeling epilepsy with pluripotent human cells. Epilepsy & Behavior : E&B, 14 Suppl 1, 81-85.

Nagano, K., Yoshida, Y., & Isobe, T. (2008). Cell surface biomarkers of embryonic stem cells. Proteomics, 8(19), 4025-4035.

Nichols, J. E., & Cortiella, J. (2008). Engineering of a complex organ: Progress toward development of a tissue-engineered lung. Proceedings of the American Thoracic Society, 5(6), 723-730.

Park, D. H., Borlongan, C. V., Eve, D. J., & Sanberg, P. R. (2008). The emerging field of cell and tissue engineering. Medical Science Monitor, 14(11), RA206-20.

Patwari, P., & Lee, R. T. (2008). Mechanical control of tissue morphogenesis. Circulation Research, 103(3), 234-243.

Pellegrini, G., Rama, P., Mavilio, F., & De Luca, M. (2009). Epithelial stem cells in corneal regeneration and epidermal gene therapy. The Journal of Pathology, 217(2), 217-228.

Phelps, E. A., & Garcia, A. J. (2009). Update on therapeutic vascularization strategies. Regenerative Medicine, 4(1), 65-80.

Piscaglia, A. C. (2008). Stem cells, a two-edged sword: Risks and potentials of regenerative medicine. World Journal of Gastroenterology : WJG, 14(27), 4273-4279.

Reinecke, H., Minami, E., Zhu, W. Z., & Laflamme, M. A. (2008). Cardiogenic differentiation and transdifferentiation of progenitor cells. Circulation Research, 103(10), 1058-1071.

Riazi, A. M., Kwon, S. Y., & Stanford, W. L. (2009). Stem cell sources for regenerative medicine. Methods in Molecular Biology (Clifton, N.J.), 482, 55-90.

Sakai, D. (2008). Future perspectives of cell-based therapy for intervertebral disc disease. European Spine Journal, 17 Suppl 4, 452-458.

Sanchez-Martin, M. (2008). Brain tumour stem cells: Implications for cancer therapy and regenerative medicine. Current Stem Cell Research & Therapy, 3(3), 197-207.

Scharfmann, R., Duvillie, B., Stetsyuk, V., Attali, M., Filhoulaud, G., & Guillemain, G. (2008). Beta-cell development: The role of intercellular signals. Diabetes, Obesity & Metabolism, 10 Suppl 4, 195-200.

Siniscalco, D., Sullo, N., Maione, S., Rossi, F., & D'Agostino, B. (2008). Stem cell therapy: The great promise in lung disease. Therapeutic Advances in Respiratory Disease, 2(3), 173-177.

Srivastava, A. S., Malhotra, R., Sharp, J., & Berggren, T. (2008). Potentials of ES cell therapy in neurodegenerative diseases. Current Pharmaceutical Design, 14(36), 3873-3879.

Stocum, D. L., & Zupanc, G. K. (2008). Stretching the limits: Stem cells in regeneration science. Developmental Dynamics, 237(12), 3648-3671.

Stoddart, M. J., Grad, S., Eglin, D., & Alini, M. (2009). Cells and biomaterials in cartilage tissue engineering. Regenerative Medicine, 4(1), 81-98.

Thanos, C. G., & Emerich, D. F. (2008). On the use of hydrogels in cell encapsulation and tissue engineering system. Recent Patents on Drug Delivery & Formulation, 2(1), 19-24.

Tweedell, K. S. (2008). New paths to pluripotent stem cells. Current Stem Cell Research & Therapy, 3(3), 151-162.

Weissman, I. L., & Shizuru, J. A. (2008). The origins of the identification and isolation of hematopoietic stem cells, and their capability to induce donor-specific transplantation tolerance and treat autoimmune diseases. Blood, 112(9), 3543-3553.

Yamahara, K., & Itoh, H. (2009). Potential use of endothelial progenitor cells for regeneration of the vasculature. Therapeutic Advances in Cardiovascular Disease, 3(1), 17-27.

Yamahara, K., & Nagaya, N. (2008). Stem cell implantation for myocardial disorders. Current Drug Delivery, 5(3), 224-229.

Yokoo, T., Kawamura, T., & Kobayashi, E. (2008). Stem cells for kidney repair: Useful tool for acute renal failure? Kidney International, 74(7), 847-849.

Zhou, Q., & Melton, D. A. (2008). Extreme makeover: Converting one cell into another. Cell Stem Cell, 3(4), 382-388.

The Biology & Medicine of President Obama’s Graying Hair (and Ours as Well).

It is somewhat ironic that in a time of economic crisis and two wars, the front page of the New York Times today (Thursday, March 5, 2009) features an article by Helene Cooper (cited below) on the increase in the amount of gray hair on the president’s head after only 44 days in office. 

 

To be fair, one of her main points is that presidents tend to get grayer much quicker than the regular population, presumably owing to the greater stress they experience on the job.

 

Perhaps serendipitously, a major review of the causes of graying hair, which introduces important new experimental data, appeared only last week, in the FASEB Journal. (cited below as Wood et al.)

 

There has been a long list of theories about the causes of graying hair, but more and more consensus has been building up, largely based on on long-range population genetic studies and on some experimental data.

 

Graying  is,  by the way,  a phenomenon that humans share with many mammals, who often have lightening or whitening and graying of their fur with increasing age.

 

Indeed, lab mice are the traditional experimental animals of choice for the study of graying hair. But as we will see shortly, this is changing.

 

Graying Owing To Less Efficient & Dying Off Pigment Cells

 

The most prominent explanation at the cellular level for graying  hair, is a breakdown in one of the  two major cell types that contribute to hair growth.

 

These cell categories are the keratinocytes, and the melanocytes. They live together in the follicle, the bulbous structure at the base of a hair,  located in  deepest layer of the skin.

 

Basically, melanocytes (sometimes called pigment cells) provide the color through leaking it into the keratinocytes.  Through their own physiologically normal, planned cellular death, the now tinted  keratinocytes provide the protein keratin whose build up after their deaths, results in the growth of a shaft of hair.

 

Despite what one hears on TV ads about making one’s hair “come alive” or get “more lively,” all hair shafts , are, in fact, dead and incapable of reanimation. Only the cells within the follicle are alive.

 

The effects  of various shampoos, crème rinses, and mousses, works by softening the inanimate fiber much as water might soften straw or fabric softener relaxes  cotton, wool or polyester fibers in cloth.  Damaged hair is generally the result of applying the wrong substances, too much of the right substances,  or  too much heat or sun that damages the underlying skin or reduces the overall level of moisture in the scalp.

 

The particular color (and curl or lack of it), of one’s hair (blond, red, brunette) is driven by underlying genetics, but the intensity of that color is built on the productivity of the melanaocytes in making melanin, and on the amount they manage to diffuse into keratinocytes.  

 

The standing theory was that the melanocytes first start producing less melanin as they age, and then, the melanocytes themselves die out.

 

The keratinocytes keep making keratin, and through their dying, leave the keratin to grow into hair. But with less, and eventually  without any,  melanin, soon  the hair appears grey or white.

 

Turning Gray “Overnight”

 

What causes a sometimes noticed or reported sudden  increase in the amount of gray hair is not so much the simultaneous deaths of all the melanocytes, but rather, an increase in the number of hair strands lost each day, that adversely favors the older hair strands, in a kind of statistical trend.

 

The oldest hairs, which grew when there was more melanin production, are typically the most strongly colored hairs,  and they fall out,  naturally enough, first.

 

Some white or gray strands also fall out, so that initially, the balance of dark to gray or white seems to be only slowly tilting towards the gray or white.

 

But according to traditional theory, eventually more follicles have fewer or less productive melanocytes, and the hair they keep on growing turns grayer or whiter.

 

This means that with every hair shed, the replacement hair  shaft will be more likely to be gray or white, because more of the purely darker hairs will not be replaced.

 

The end result is that there are fewer darker hairs to mask the presence of the gray or white ones, which now stand out much more starkly.

 

The number of hairs lost daily is well known to be under the influence of not only genetics, and aging, but also nutrition,  certain medicines and diseases, chemotherapeutic drugs, and fairly often, physical or mental stress.

 

Accelerating hair loss simply speeds up the shedding of  hairs of all colors,  with the remaining hairs and succeeding  hairs more likely to be gray or whiter sooner.

 

Hydrogen Peroxide: Good for Making Some People Temporarily Blonde,

But An Aggressive Co-Factor in Turning Everyone’s Hair Gray or White

 

While there are many nuanced innovations  that could be reported about the Wood et al paper, two are particularly notable.

 

The first is their improvements on a system for viably culturing human follicle cells in what amounts to Petri dishes. (The source of the hair follicles was   skin  removed  during facelifts done during cosmetic surgery.) This allowed for fewer discrepancies and less tentativeness in drawing conclusions formerly  caused by the use of lab animals.

 

The second was a system for precisely tracking the amount of certain proteins and metabolic residues in hair follicles, and in the hairs themselves, using  Fourier-Transform Raman spectroscopy.

 

Their ultimate conclusion was that a significant build up of hydrogen peroxide and metabolic complexes ultimately disabled the production of the melanin through poisoning of intermediate steps towards its production. Most notably it interfered with tyrosine-based precursors of melanin.

 

It was shown that gray and white hairs had massive  amounts of the suspect biochemicals, and that darkly pigmented hairs had virtually none at all.

 

In a sense, the destruction of melanin-making is caused by the melanocyte’s and keratinocyte’s declining abilities  to clean up the waste products of the making and incorporation of melanin.

 

The hope of this new research is not for hair care products that dye the dead hair shaft but for hair and scalp treatments that help break up the unwanted buildup of hydrogen peroxide and scavenge incomplete metabolic byproducts, so that melanin production can continue in the living melanocytes.

 

In the meantime, try hard not to worry about the rate at which your hair is going gray or white. It will only increase hair loss, and you now know that is ultimately not a good thing if going gray or white bothers you.

 

Besides, you will only court derision from people proud of their new hair color, or from people who have gone bald, and wonder why  you consider yourself so badly off.

 

 

 

Tony Stankus [email protected] Life Sciences Librarian & Professor

University of Arkansas Libraries MULN 223 E

365 North McIlroy Avenue

Fayetteville AR 72701-4002

Voice: 479-575-4031

Fax: 479-575-4592

 

Arck, P. C., Overall, R., Spatz, K., Liezman, C., Handjiski, B., Klapp, B. F., et al. (2006). Towards a "free radical theory of graying": Melanocyte apoptosis in the aging human hair follicle is an indicator of oxidative stress induced tissue damage. The FASEB Journal, 20(9), 1567-1569.

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Cooper, H. (2009). 44 days in the White House, and the hair? Grayer already.  New York Times, 158, (54,605),  A1, A19.

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Sarin, K. Y., & Artandi, S. E. (2007). Aging, graying and loss of melanocyte stem cells. Stem Cell Reviews, 3(3), 212-217.

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Viral Oncolysis or Oncolytic Virotherapy: Viruses Modified to Attack Tumors

Mankind has long  suffered from virally-based diseases like rabies, polio,    influenza, the common cold and in recent decades AIDS.

According to a fascinating review by Kelly & Russell (cited below, and which this blogger particularly commends to your attention as a read-me-first), the idea that at least some of those viruses sometimes could have  unanticipated good side effects came from isolated case reports.

In these occasionally encountered notices from family doctors  within medical journals,  patients who had some well-diagnosed form of cancer, typically blood born,  but also some solid tumors, and who subsequently caught influenza, the mumps, or the measles or some similar viral ailment,  sometimes went into cancer remission.

A few brave experimentalists (with their equally brave or perhaps unwitting patients)  sought to deliberately introduce live viruses in largely hopeless cancer cases with the hope that a similar “miracle” could be made to happen again.

The wild, untamed, viruses were introduced often via injections of crude extracts of human serum and tissues, or   of infected lab animal parts, and in a few cases by pin-prick scratches such as were used for vaccinations.

Viruses tested included those associated with   mumps,   chickenpox,  hepatitis, and even West Nile disease.

In terms of families of viral structures, there were   adenoviruses,  herpesviruses, paramyxoviruses,  and picornaviruses, although the researchers at that time often could not precisely type the varieties, because their microscopes were often not powerful enough to determine precise structures. Nonetheless, serendipitously, this was a surprisingly representative sample of general viral types,  that more modern researchers could eventually build upon.

Results were decidedly mixed. Not surprisingly, many of the patients showed quite  a feverish immune reaction, with some acquiring the viral disease full-blown. Others had acute reactions at the injection site or in surrounding tissue, particularly in the nervous system, or developed encephalitis.

Many trials involved a number of patient deaths directly attributable to the treatment rather than the underlying cancer.

Nonetheless, a significant percentage (not usually a majority, but as much as a third in some clinical trials) showed remissions in their cancers.  This often took the shape of solid tumors that began dying off through rotting internally, or in blood counts that returned to normal levels.

Given that virtually all of the patients would have otherwise soon died of their cancers, this was not a trivial outcome.

The problems were that most of the remissions were relatively brief (a matter of months) and starting in the 1950s, other cancer treatment approaches like radiation, chemotherapy and surgery were showing better and longer   lasting results, making viral treatments seem relatively unpromising by comparison, and certainly riskier for the patient in many cases.

Progress  in viral oncolysis was fitful, and was additionally frustrated by the fact that, time and again, many seemingly successful  lab animal experiments yielded poor results when tried on humans.

One limiting factor was clear even in the 1950s: Using live human disease viruses, while effective in a good many patients at first, was ultimately self-limiting.

The patient fought the viral disease immunologically and the viruses intended for killing tumors, themselves got killed off before being able to finish their “oncolytic” job.

The strategy then shifted to viruses that attacked animals other than humans, to which humans were immune or to which they became only mildly ill. Under this scheme, the viruses could attack the tumors without themselves being wiped out by the body’s counterattack.

The first real winner in a wide search was the Newcastle virus. It wreaks havoc with poultry but most humans suffer mildly if at all. It continues to show good results in patients with certain types of melanoma.

The second winner in breaking down a small range of  solid tumors was vesicular stomatitis virus. This pathogen  primarily bothers only cattle, giving them mouth blisters, sometimes with involvement of dairy cow teats, and hooves. Later scientific analysis showed that it attacked only those human tumors with impaired interferon function.

Nonetheless, analyses like these showed that  viruses selected or tailored for mildness towards humans, that were   targeted towards specific tumor weaknesses,  could, in fact, succeed.

A two-fold challenge   emerged over the 1980s and 1990s: find out how  to tailor viruses, and learn the hidden pitfalls of the life as a tumor.  Genome sequencing and genetic engineering of viruses helped with this first effort, and the cell and tissue culture of tumors aided the second.

Today a number of viruses (most often mentioned are adenoviruses and vaccinia that are fundamentally less threatening )  have been built for battle with cancers. Their modes of action vary.

The most common approach is still the direct tumorlytic approach.

The injected virus preferentially invades the tumor, bypassing healthy tissue.

Virus particles penetrate tumor cell membranes, replicate themselves wildly, and generally cause the host cell to burst, releasing more virus particles to get into neighboring tumor cells, thereby repeating the cycle.

When viable tumor cells are depleted,  the rather large number of viruses remaining hopefully gets filtered out harmlessly through the liver.

Another strategy is to  inject the tumor with a virus and have that virus replicate, but not necessarily rupture all the tumor cells right away.

Rather, the increasing biochemical maintenance demands of this  invading virus (typically called a suicide virus) makes the whole cell-virus complex susceptible to a follow-up injected drug, which might otherwise not kill either the cancer cell or the virus directly, but now clearly kills both.  

The advantage of this approach is that such follow-up drugs are often not toxic to the healthy cells of the patient, since they require   special activation by the peculiar biochemical condition of the host cell-virus complex, to do their cell killing.  Once the destruction has occurred they are disarmed because they are  once again without the biochemical triggers that make them actively toxic, and can circulate until filtered out by the liver.

A third strategy is to tailor the virus so that it anchors on the cancer cell surface and blocks some pore whose function is vital to the cell. The tumor cell eventually fades from disruption, often of its cell-cycle.

A newer variant of this are viruses engineered to anchor themselves firmly to the cancer cell membrane with one end of their structure, but which then grab with another end of  their  viral self onto the tail of the tumor cell’s own DNA strands. This keeps the cancer’s cell’s own replication machinery   from participating in the cell cycle so no metastasis can occur. 

Which cancers  are being most actively researched with respect to viral oncolysis?

Most often mentioned are colon, prostate, and cervical.  Less often, tumors of the breasts, and liver, as well as melanomas are reported as candidates for this new (but at the same time very old) approach.

Tony Stankus [email protected] Life Sciences Librarian & Professor

University of Arkansas Libraries MULN 223 E

365 North McIlroy Avenue

Fayetteville AR 72701-4002

Voice: 479-409-0021

Fax: 470-575-4592

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Functional Food Health Advertising : Is Everything that Is Claimed to Be "Bioactive" or an "Antioxidant" Really Essential in Such Great Quantities or from Specific Food Types? Plant-Based Sources Are Abundant But Evidence is Not

One way of defining functional foods is that they are consumed for day-to-day energy balance and bodily maintenance but “may” have additional health benefits.

Functional foods are like regular foods  in many ways. Just as in foods that do not advertise themselves as being nutraceutical or functional, their “Nutrition Facts” label  clearly indicates a number of calories,  along with quantities and percentages of  given types of carbs, fats, vitamins and minerals contained, and how much of the recommended daily needs are met by consuming a suggested portion.

The difference is that while there is widespread scientific and clinical consensus on the standards for accuracy of that Nutrition Fact Label information,   as well as support  for the efficacy and safety  of the nutrients that are mentioned on that label, there is often significantly less factual basis for much of the additional “scientific”-sounding terminology that appear elsewhere on package labeling or in advertising, that suggests those “additional health benefits.”

The most important new health claims are made in bold lettering and only partly offset by fine print warnings that these foods are “not intended or claimed to aid in the diagnosis or treatment of any specific diseases.”

Nonetheless, there is a great rise in the use of terms such as “bioactive ingredients” as if  all  substances tagged with this,   were clearly beneficial to a significant degree for human health.

“Bioactive” simply means that the ingested materials are likely to react chemically within the body, as opposed to being relatively inert. In point of fact, the poisons in  mushrooms and snake venom are also “bioactive”.

“Bioavailable” is actually a more useful term, in that it should indicate what proportion of  the purported active ingredient is actually released into the body in a way the body can use. In other words, a proposed functional food, like a fish,  may be potentially a good source of calcium if one eats the bones. This might be fine for sardines, but, apart from any choking it would cause,  swallowing the bones of a codfish would not likely cause for much release of the calcium in a form useable by the body, because the calcium in large fish bones is not particularly “bioavailable.”   

  And one increasingly finds  in nutraceutical and functional food marketing  mention of their products having specific   categories of  naturally occurring compounds that share some characteristic chemical structure or have purported pharmaceutical functionality. 

The technical definition, molecular formula,  and 3-D drawing of these compounds would make for a good test question for courses in advanced bio-organic chemistry. But the names of these compounds   are instead, tossed out to the lay public as if that knowledge was common or self-explanatory.

In reality these compounds  are  vaguely perceived as being “something medical and important”  to most consumers. These compounds  are consequently inferred by the consumer to be  something essential to their very survival, or at least something of which they ought to have more of, to avoid any “unhealthy deficiency.”

The Best Case Scenario: Antioxidants

Antioxidants are any chemical compound that reduces electron loss in chemical compounds ----- indeed “reducing agent”  would be an equally valid term, although not one in common usage in human nutrition. 

The aim of reducing oxidation is to stabilize the structure of many biochemicals within the body, which function best in an unoxidized state, or in some cases, seriously malfunction when oxidized.  

The causative agents promoting these malfunctions are generally termed “free radicals,” although in Cambridge, MA and Berkeley, CA, they are probably re-named “ bourgeois capitalistic tools, “ to avoid offending the bulk of the populace.

Antioxidants in general have the most conventional science in their favor. Indeed, it is now well established that vitamins A, C, E, beta-carotene, and the trace element selenium work at least partly through their antioxidant capabilities, and recommended minimum daily requirement have long been established.

There is indeed some evidence developing that they may work by helping to stabilize the process of DNA replication, and that some people could benefit even more from these antioxidants if an optimal match could be made between their genetic needs and the antioxidants that would best support this stability, fostering   a  new field of Nutrigenomics.

What is not clear is what are the specific levels of  total antioxidants of all types, one must have before there are  too many or too  few for good health.  The underlying goal   is to somehow have enough of a supply of antioxidants to avoid adverse effects, without shutting necessary oxidation activities (like breathing and digestion!).

There are, unfortunately, many more claims that antioxidants “boost immunological functioning”, “cognitive ability”, and “reduce infection and inflammation” and even cure the common cold, than there is evidence that any of these assertions are true.

There is some evidence that the body is less capable of handling   free radicals  with increasing age, but, unlike some claims made in advertising, it is not clear that  an insufficiency of dietary antioxidants causes aging (it is clear to me that living for a long time causes aging) as well as diseases of cumulative effects like some cancers, and macular degeneration.

There is a good deal of epidemiological information that people who consume diets naturally rich in antioxidants ------typically five or more servings of vegetables and fruits -----are healthier. And, at least in the case of macular degeneration, there is evidence that consuming mega-doses of certain antioxidant vitamins (specifically the Age-Related-Eye-Disease-Study or AREDS formulation) slows the progression of macular degeneration, although it is not clear that an absence of antioxidants was the cause of the disease in the first place.

There is conversely some evidence that an overabundance of some of these antioxidants  (vitamins  A,  E and beta-carotene) can increase mortality in certain populations. Smokers with early macular degeneration are given a modified formulation of  AREDS vitamins for this very reason.

What specialized categories of antioxidants seem to be making the news most often as being parts of nutraceuticals or functional foods? Lets look briefly at a few categories.

Carotenoids

Lutein, zeaxanthin, and lycopene are among the most commonly mentioned antioxidants. They are called carotenoids, quite frankly because they were first isolated in carrots, although they are widely available in many leafy  green plants (but overshadowed by the green pigments). Most of these antioxidants are naturally colored with shades ranging from yellow (marigold petals are used in most AREDS formulations) to orange (carrots)  to red (lycopene, for example is particularly found in products made from ripe tomatoes).

The Polyphenols, Particularly the Flavonoids

The nomenclature for the flavonoids comes in part from the Latin term for  blond and indeed, a dynasty of Roman emperors, the Flavians, were all (real or bottled) blondes (and major league throwers of Christians to the lions.) .

In fact, this is another family of yellow to red colored compounds with antioxidant capabilities, although their organic chemical structure involves more carbon rings ( particularly phenolic rings) than the carotenes, and there is a branch of this  chemical family that also has blue and green tints.

Like the carotenes,  polyphenols are largely present   in fruits and vegetables, particularly highly colored berries, grapes and citrus.  But owing to that blue-green branch, they can also be found in tea and cocoa plants.

Not too surprisingly, the polyphenol  antioxidant resveratrol, which is found in darkly-colored grape skins , has suggested that red wines in particular, might well function as nutraceuticals. Peanuts, it turns out, also have a significant amount of this category of antioxidant.

Isothiocyanates

Sharing a blue-green coloring with one branch of the flavonoid family are for some members  the  Brassica or Cruciferous  family of plants. Broccoli, Brussel sprouts, cauliflower, horseradishes, kale, mustard greens, radishes, turnips, watercress and even wasabi   are included, although to date,  few functional foods seem based on these healthful, but frankly gassy plant foods.

Carbon Sulfides

While hydrogen sulphide, the smell of rotten eggs,  is arguably the strongest stink on the planet,  the organo-sulphides are another, and rather popular,   class of functional food antioxidants, despite their sometimes overpowering smell. The most famous of these are various garlic-based supplements.

The Need for Standards in Making Claims of Quantity, Quality & Efficacy

There is indeed, growing evidence that nutraceuticals and functional foods that contain antioxidants that do just what they claim to do: promote human health, although the extent is quite unclear.

But there is at least as much evidence that the so-called health-food and nutritional supplement industry sometimes plays fast and loose with the levels of the antioxidant  that are present, from batch to batch,  or which are in fact, truly “bio-available” and in general, exercises less quality control, by far, than the convention medical/pharmaceutical industry. The paper by Griffiths et al. in the January 2009 inaugural issue of the Journal of Functional Foods , below outlines an excellent proposal for this industry to adopt the Council-of-Experts” approach used by the US Pharmacopeial Convention, Inc.

Tony Stankus [email protected] Life Sciences Librarian & Professor

University of Arkansas Libraries MULN 223 E

365 North McIlroy Avenue

Fayetteville AT 72701-4002

Voice 479-409-0021

Fax 479-575-4592

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Could Persistent Nasal Misery Be Relieved By a MIST? Chronic Rhinosinusitus and Minimally Invasive Sinus Technique

Nasal Sinus Problems  Vary by Individual But Collectively Are Surprisingly Common and Very Energy-Draining

Does it sometime appear that a rather small organ or appendage, namely, your nose, seems to   take near-complete  control of your life? 

A constantly runny nose that must be blown frequently,  turns many of us red-nosed in appearance, not unlike Rudolph the Reindeer or a fairly severe alcoholic you might meet on the street.

Conversely, nasal congestion or stuffiness  changes the pitch and timbre of our voices so that we sound like those people in B- grade  movies or on low budget cable TV crime reenactment stories trying to phone in a ransom demand with a voice  vaguely disguised by putting a handkerchief over the  mouthpiece.

It is not unusual for many patients to have sinus headaches, where the nasal blockage or  inflammation is caused by abnormal build-ups of pressure in one or more of the several sinus cavities.

Of course, one of the ways the body attempts to resolve blockages or react defensively to an irritating situation, is the socially awkward mechanism of sneezing. Which curiously enough, if repeated several times, tends to become self-sustaining since the attempt to discharge an irritating substance or break through a log-jam of sorts, eventually further irritates the linings of the nose, throat, and back of one’s mouth, perpetuating the cycle.

And there can be the infamous post-nasal drip where phlegm and mucus seem to be redirected in unnatural amounts and  colors down the back of own’s throat, prompting all manner of coughing.

 What all have in common, if they last long enough, is the patient’s exhaustion.

This is not caused because you’ve been chopping wood. It’s just that you cannot be well-oxygenated if you can’t breathe freely.

While this can be somewhat consciously offset through the  awkward but manageable practice of mouth-breathing for daytime hours, significantly increased snoring and even apneic episodes can occur due to blocked nasal passageways.

This impedes refreshing sleep  and oxygenation that is vital for you continue to function optimally. Instead, with unremedied nasal sinus symptoms,  you just keep increasing your sleep deficit and O-2 desaturation  levels.  

And in many cases, one loses his or her sense of smell.

Or worse, gets a distorted sense of smell. Things that are supposed to be smell appetizing, have no interest, and worse yet, things that smell bad (coming from you or from somewhere  in the environment around you) do not offend you enough to take corrective or evasive actions.

All of these conditions are manifestations of  sinusitis, an inflammation of the nasal and facial cavities (sinuses).

These can be  caused by infection, allergy, or pollution, and are mostly commonly encountered by most Americans in conjunction with a “head cold” or the “flu.”

According to the National Institute of Allergy & Infectious Diseases’ website , www3.niaid.noh.gov/topics/sinusitis/ , there are 37,000,000 new cases of acute sinusitis reported every year, with symptoms lasting from  days to a few weeks.

In addition, there appears to be a deep reservoir of 32,000,0000  chronic rhinosinusitis patients who suffer from months to years with limited relief, if any.

Particularly affected are asthma sufferers, and devastatingly affected are children with cystic fibrosis.

Conservative Over-the-Counter  Medical Regimes

Work for Many  Patients in the Short Run

Symptomatic relief from sinusitis for many people comes from over-the-counter pills or capsules. These typically contain pseudoephedrine or phenylephrine. They reduce inflammation by shrinking the blood vessels in your nose. This, in turn, cause the swollen membranes to shrink back, allowing freer breathing, and coincidentally helps promote a return to normal mucus production (neither too much nor too solidified).  

Antihistamines, which are frequently combined with decongestants,  work to reduce inflammation by modulating the cellular immune response that increases swelling and mucus production.

A wide variety of antihistamines are available, with generic names like chlorpheniramine, bromopheniramine,  diphenhydramine, and loratadine.

Decongestant/antihistamine-like compounds are also available in spray bottles for instilling into the nose.

A saline solution is often the base of the contained fluid, as this has its own antiseptic and mucus-managing properties.

Many such sprays give prompt relief, but if used for more than three days, the nose actually becomes dependent on them. Ultimately over-use can cause its own “rebound” problems, some as bad or worse than  the original condition.

Outright flushing or irrigation of the nasal cavities is gaining a fair amount of attention, and, as in more widely and conventionally used  nasal sprays, a saline solution is the base as a low-grade mucus solvent and flusher of allergens or hardened debris.

Intriguingly, the use of solutions including baby shampoo have been reported as successful, although the patients involved had been those who had already had a surgical procedure performed.

One or more of these previous over-the-counter steps is likely to have resolved the short-term nasal sinusitis problems for at least 90% of sufferers.

Prescription Treatments Can Often Help Those for Whom Over-the-Counter Preparations Were Insufficient

The most common step up from any of these over-the-counter treatments, for the remaining 10%,  is the prescription of antibiotics, on the assumption that the sinusitis is caused by a bacterial infection, or that the build-up of mucus provided a home for unwanted bacteria, so that the infection was actually secondary to the initial complaint.

Unfortunately, there is a substantial amount of doubt that most of these bouts of sinusitis are initially bacterially caused (most often they are viral or allergic responses). Over-prescription of these drugs in the event of colds and flu is now generally regarded as inappropriate, because it builds up drug resistance.

There is somewhat greater success in reducing opportunistic fungal infections, which actually occur more often, through prescriptions.

Genuine nasal bacterial infection, either primary or secondary to the sinusitis,  is encountered in a minority of cases. Unfortunately, it increasingly involves  MRSA: methicillin-resistant Staphylococcus aureus. 

MRSA is singularly difficult to eliminate   in the nose, this type of staph seems to populate the membrane system of the sinus cavities in a particularly well-defended  location.

MRSA  appears to construct ---- or at the very least densely  populate ----a kind of  an envelope of  protection: a biofilm.

Biofilms are the result of a collective action on the part of some communities of micro-organisms, sometimes including fungi,  that allows them to build a thin, polymeric protective barrier out of their own metabolic waste-products or uses apoptotic layers ----essentially a lining of dead bacterial cells, kind of like a callus of dead skin-----as a shield.

The biofilm is semi-permeable. It not only provides the  bacteria  with shelter,  but allows enough nutrient influx, to  subsist to some degree upon  on the nasal mucus and quite possibly receives metabolic gas exchange through the capillary system of the nose.  

In essence,  nasal populations of MRSA not only seize the dwelling, but hijack the ongoing deliveries of what are literally vital supplies.

Permanence of any bacterial infection in the nasal sinuses is a problem . Given that the nose drains at least partly into the upper respiratory system, which connects to the lower one, the chances for vastly more serious MRSA infections as seen in pneumonia, and even sepsis  are very real.

A key step in MRSA control, ironically whether or not the antibacterial medications worked well through direct action  in any  particular patient,   would be the elimination of the inflamed  nasal sinus lining substrate that makes this sort of malevolently populated  biofilm possible.

One way this is done is to use   nasal sprays that contain light doses of steroids or steroid-like compounds.

The theory is that a topically applied spray of liquid, leads to a localized reduction of chronic inflammation. This in turn   leads to a sharp reduction in the favorability of the nasal sinus environment  that could support opportunistic hostile infections. Essentially this is an antimicrobial effect,  even if the steroids themselves are not antimicrobial by direct action.

It is clear than sprays of this type have the potential to reduce inflammation effectively for an intermediate amount of time, sometimes months, and perhaps a year. But, just like the milder over-the-counter nasal sprays,  their  longer run use   may evolve into a kind of habituation and dependency on  the spray to govern the  nasal sinus equilibrium on its own.

In other words, if it does not work right away, the steroid does not so much set the stage for a return to a more natural equilibrium: The equilibrium cannot be maintained without the steroid.

This leaves the physician with the option of systemically delivered steroids, most often given in pill form.

Often even more problematic is the long term taking of oral steroids like prednisone.  These do calm inflammation responses effectively, particularly at first , even at low doses.

But ultimately, their effectiveness at low doses wanes and higher doses are required. Moreover they actually reduce natural resistance to infection, and have a host of other potential problems with long term use.

These include stomach irritation, “ fattening of the  face” effect, osteoporosis, and in some cases, mood swings, and even psychosis.

Nonetheless, by the time various prescriptions have been tried, as high a proportion as  96% will have been satisfactorily treated.

Unfortunately, the remaining small percentage simply does not get any better. They get worse. They don’t die off quickly. It seems as if their lives are dying in little steps: time lost from work, opportunities for good sleep gone, inability to participate in customary  physical activities,  and  no ability to actually appreciate  good tastes and pleasant scents.

Essentially,  every year,  several hundred thousand of nasal sinusitis patients move from the ranks of the 37,000,000 acute cases, the vast majority of which will be effectively cured, to the sad growing accumulation of 35,000,000 for whom no medical cure seems to have worked.

Is The Last Line of Defense, Surgery,   a  Drastic Step?

What then is left?  Two surgical approaches, with the second really a variant of the first.

The first is traditional Functional Endoscopic Sinus Surgery, FESS.

FESS is  done with an emphasis on enlarging nasal sinus ducts,  cutting both soft and bony tissue. It enlarges  the “holes in the bones”  so that patent airways  can be re-established, much as a traffic-clogged underground tunnel could be enlarged through gouging into the surrounding rock walls to make way for extra traffic lanes.  

But this is by no means a crude procedure. Conventional x-rays, CAT scans, MRIs, and even SPECT imaging helps guide the surgical plan of attack, so that airways are re-established in the most severely occluded situations, particularly if there is bony debris from past disease processes (or the concomitant problem in some patients of nasal polyps).

 FESS has an absolutely  solid record of providing a great deal of relief, and scores well in post-operative exams of patients that verify the continuing presence,  and physically measure the extent  of the cleared airway, weeks and then months later.

Once the nasal sinus passages have healed and firmed up (particularly  toughened up), the sinuses seem to be less welcoming of foreign microbial invaders  probably by becoming less  conducive to the forming of biofilms. 

Gratifyingly, post-operative  Quality-Of-Life, QOL surveys disclose high ratings from the vast majority (well over 90%) of patients who were previously recalcitrant to medical interventions. They feel much better and generally experience an overall brightening of mood. They are less fatigued, and most, if not all their sinus pain is gone.

What is the second approach?

Minimally Invasive Sinus Technique: MIST.

MIST abandons the idea of working intentionally on the bony material, and instead focuses on the soft tissue  at sinus drainage “choke-points” as it were.

The idea is to go thoroughly through all of these choke points successively during the same procedure.

This has two obvious advantages.

First, healing times, and blood loss is minimized. Dealing only with soft tissue is far less traumatic or dramatic surgery. A 15 minute procedure is not unusual.

Second, because it involves a standardized,  systemic clearing process of the whole system of check-points, including both obviously major  and less-obviously minor choke-points that could eventually become major,  the procedure appears to be at least as preventative as curative.

And, as a practical matter for ENT surgical training, MIST allows for consistency of treatment ( and often consistency of results )  in both very experienced and less-experienced hands, because what gets done is the same for every patient.

How does MIST compare with FESS?

Very favorably thus far, with roughly equal post-surgically measured patency of drainage-ways, and perhaps even greater QOL scores, because the procedure was less frightening, involved less loss of work time, and relatively minimal blood loss  and shorter times or minimal use  of  uncomfortable nasal packing.

The choice of which surgical procedure is best for a particular patient is, of course, best resolved between an oto-laryngologist and his or her patient. The amount of data  supporting FESS is still greater, because more ENT surgeons have been using it longer, and there may be some situations where it is going to remain superior to MIST.

But in an increasing number of oto-laryngologic practices , the point is moot. Today, a great many surgeons in this field can perform both types of procedures.

Is surgery then, an infallible last resort? Does it work equally well for all types of patients.

No, there will be a small percentage of patients, perhaps less than 5%, who will need continued combination medical therapy (often irrigations or sprays) and and perhaps surgical revision (doing   the procedure over again.)

Which groups do less well with these surgeries? Women, people with aspirin intolerance, people who are chronically depressed, smokers, some asthmatics, and people who have had previous surgical procedure in this area, do somewhat less well.

But even so, most of these patients, in their QOLs report a great improvement, and given the choice would do it again.  

Tony Stankus, [email protected] , Life Sciences Librarian & Professor

University of Arkansas Libraries MULN 223 E

365 North McIlroy Avenue

Fayetteville, AR 72701-4002

Voice: 479-409-0021

Fax: 479-575-4592

 

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Good Things Come in Small Packages: Custom-Designed Nanoparticles in Drug Delivery and Medical Imaging Contrast Media

There has been heightened excitement -----and a modicum of worry----- about the rise of nanoparticles in clinical medicine. Scarcely a day goes by without someone announcing new findings or proposing new applications.

Nanoparticles  in Medicine Are Very Small & Quite Diverse

There is no place on the periodic table where the nanoparticle lives. It is not a chemical element.

It is not even a molecule.

Nor are nanoparticles even a single class of drugs by either mode of action (e.g. proton pump inhibitors)   or by disease being fought (e.g. antimalarials), although they can be made to do either of those jobs.

What binds together nanoparticles as a concept is their size. They are all measured and characterized in billionths of a meter.

As an illustration in the Thursday, December 4, 2008, New York Times (page E3) helps us visualize, a single nanometer is about the size of a glucose molecule, while an antibody might be 10 nanometers; a virus 100 nanometers, a bacterium 1000 nanometers, and a red blood cell 10,000.

What makes this size range important is that nanoparticles have the potential, like glucose molecules, antibodies, viruses, and even some bacteria, to make their way into cells and tissues.

This essay will look at three general types of nanoparticles seeing a good deal of research interest and sometimes clinical applications.

Dendrimers

Dendrimers are tree-like nanoparticles in the sense that they have a central trunk from which branches sprout, only to have more branches sprout from those branches and so on.

Ultimately one has a very tiny tree with a particular advantage: even tinier birds and squirrels can build hidden nests in it.

Why would this be good? 

It turns out that many dendrimers are not automatically rejected by cells or tissues, as are most foreign substances, including many drugs, but pass through cell membranes somewhat easily, bringing along drugs  or medical imaging contrast dyes that otherwise could not make it through.

Thus far, results have been promising for dendrimers as higher-level efficiency delivery vehicles of antioxidants and antiinflammatories, particularly in otherwise insoluble blood-brain-barrier dilemmas like repairing damaged brain glial cells.

Quantum Dots

Quantum dots are like a computer microochip in that they have a chemical composition usually involving some transition metals and rare earths: Cadmium, selenium, tellurium, as well as the more common silicon, zinc and  sulphur.

And as in some computer microchips, gold and platinum may be used to add a kind of chemical toughness, since these “noble metals” can rarely be successfully attacked by the body’s biochemistry. 

Like computer microchips, these “nanodots “ can be etched to have specific semi-conductor-like electronic properties.

For example, small as they are, they can have the equivalent of both transistors and resistors, or can be light-emitters at one wavelength while being light absorbers at another. 

In other words, they can be made to be bi-functional, and may be able to be turned on, and turned off, depending on the instructions or signals they receive.

What makes quantum dots biomedically interesting is two-fold.

First is their capacity to introduce silencing RNAs (siRNAs) into cells, through a kind of electrochemical bonding with the RNA. Silencing RNAs have the capacity to disrupt DNA expression, and given the right kinds of DNA disruption, cellular death can be promoted.

For example, let us imagine that we know that a certain protein is vital for the continued survival and growth of a tumor. Instead of trying to kill the tumor with overall cytotoxic chemotherapy, or with the use of focused energy beams or radioactive beads, all of which have the potential for collateral damage, we instead introduce specifically silencing RNAs.

Much like drugs that kill large tumors by cutting off their blood supply, quantum dots could deliver silencing RNA that would cause the cellular machinery of  even very small tumors to grind to a halt, and likely collapse before they ever get to any size.

The second area of promise for quantum dots is as a contrast medium for enhanced medical imaging. 

The array of diagnostic chemical dyes and labeling radioisotopes available today for post-biopsy  use in the modern pathology lab “in vitro” is impressive, but the number of those that can be used within the living patient “in-vivo” still lags, and those that exist often have the potential for providing the pathologist with ambiguity.

The typical “in-vivo “ dye or contrast medium enables a whole organ (the brain) or a general category of tissue (collagen) or a generalized process like inflammation or bone thinning to be imaged.

Scans based on these can be informative, but not detailed enough because more than one explanation can often be offered for what is detected when using general dyes and contrast media. (e.g.  The test could indicate that it could be Disease A, but maybe also Disease B, or the infrequent but benign Fluke Condition C. )

The ideal dye or contrast medium somehow binds itself to a  very specific cellular or tissue structure, or indicates the build up of a very particular fluid, or protein. With such narrow targeting, the number of plausible explanations can be cut way down.

Quantum dots can be custom built to exactly bind electrochemically to the target tissues and cells, once their molecular or cellular quantum binding requirements are known.

Conceivably, one property or   part of the quantum dot could be tailored for being a particularly good anchor onto the tissue, while another property or part could be tailored to give off electrochemical signals that could be sensed by MRIs, CAT scans, or other imaging modalities.

Indeed, it may be possible for the imaging machine to turn on the microdots by probing them at different energies or wave-lengths. Indeed, the use of magnetic fields can change the polarity of  some quantum dots so that they remain actively “glowing” only for as long as the field is in force.

Lipososomes

Liposomes are typically the largest of the nanoparticles and have been known for the longest time, largely because  natural models for making them were uncovered in the 1960s when it became possible to image some of the thinnest components of cells via electron microscopy.

To a substantial degree, the cell membranes of all animals, including humans, are mostly made with two layers of lipids. These lipid membranes serve as a bag or flexible sphere which contains all the remaining components of the living cell.

Fortuitously, many synthetic lipids also tend spontaneously to form hollow spheres, with the size of the sphere depending on chemical and physical conditions.

Through a variety of processes, including   sending vibrating shockwaves (kind of like super ultrasound waves) into lipid solutions that contained larger spheres, those spheres can be made to divide up and reform again and again into ever smaller and smaller spheres.

Those nanospheres  can ultimately be designed to include nanodoses of drugs. 

It is partly because in nature, one cellular membrane can be made to dock onto another cellular membrane, and thereby sometimes exchange inner cellular contents through their pores, and because partly in nature there can be the enfolding of a smaller cell by a larger one, which thereby takes in the contents of the smaller cell, that these nanosphere  liposomes have such content delivery potential.

Because through either method of exchange , the inner contents of the synthetic liposome can be introduced into the cells.

While the amount of drugs that can be contained in the interior of synthetic liposomes are truly infinitesimal, they have that incredible penetration power through their mimicking of natural cellular membrane processes.

As is the constant theme with most medical nanoparticle research, the drug actually goes exactly where it needs to be, and usually nowhere else, leading to fewer side effects.

While the lipids -----and certain hydrocarbon polymers that are lipid-like----used in making nanospehere liposomes are among the least “allergic” basic components of cells, in the sense of their being recognized quickly as foreign and repulsed actively ----- in contrast to foreign proteins which are very often quickly recognized and repulsed in a generalized inflammation reaction ---- the alien nature of liposomes can be further cloaked.

This is accomplished  by covering them with a single molecular layer of Propylene Ethyl Glycol, (PEG) in a process called PEGylation. The body’s immune system does not recognize  PEGylated  liposomes at all and they are even more readily taken up by the body’s cells and tissues.

Indeed, liposomes treated this way are now colloquially referred to as “Stealth” drugs, and being considered even in applications as inhalable aerosol mists that would contain drugs or vaccines.

Given their stealthiness, they do not provoke the kind of general swelling or redness at the injection site, or the kind of convulsive coughing other inhaled drugs often  induce.

Given All this Promise, What Are the Worries?

While there are all sorts of different nuances  expressed by individual  authors , the common theme of worry found in articles about nanoparticles results from the very properties that make nanoparticles so potentially effective.

We are very sure that nanoparticles are great penetrators, but what is it about them that is going “to make them want to  leave?” 

Do we want the nano-delivered drug, vaccine, RNA, or protein to stay put forever?

That is actually quite desirable in a number of cases, but that is rarely the case in image contrast dyes.

Ultimately, given that the kidney is the great filter and purifier of all manner of toxins, drugs, and dyes,  we have to be sure that in curing some very specific diseases, or in imaging some tiny but important nests of cells, tissues, and micro-tumors,  we don’t kill off these major organs with unintended effects in clearing out the nanoparticles when their job is done.

Tony Stankus [email protected] Life Sciences Librarian & Professor

University of Arkansas Libraries MULN 223 E

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Evo-Devo: Evolutionary Developmental Biology Revives Links Between Comparative Anatomy and Genomics at the Point of Embryonic Development

Biology in the 20^th and 21^st centuries  seemed to have become more and more reductionist: the answers to everything  were  ultimately going to come down to molecules, come hell or high water.

The discovery of classical genetics, followed by molecular genetics, followed by genomic sequencing represented a cascade of knowledge with strong explanatory and predictive power that was inevitably going to make clear a great deal, if not everything, about how every organism worked and even how everything evolved.

This is not to say that there were no systematizers, paleontologists, zoologists or botanists functioning who used largely anatomic similarities as indicators. It was just that their numbers and the kind of clout they had in academe seemed to diminish with each passing decade.

Their efforts to explain similarities and interrelations among extant and extinct species were regarded as place-holding attempts which provided a modicum of truth, truth that would be completely revealed once the total genomes of the species under question  could be inventoried and analyzed.

The modern evolutionary synthesis suggested that mutation pretty much explained variation, and that the survivability of variations was subject to the test of fitness: mutants that could thrive did, those that did not, well had no mutations to pass on. As long as a gene had not mutated, it did the same job it always had, and generally it was assumed, it was one gene for one job.

The response of the morphological character-based evolutionists was to get more mathematically logical, and the result to a good deal was cladistics, where traits are shown as emerging from an almost inexorable tree-branching logic, which could be tested.

If one could pinpoint where a morphological character seemed to break off, there was where the genetic mutation must have occurred and become persistent. Cladistics seemed to work very well with insects, where it certainly had its initial triumphs.

But cladistics left embryology in the lurch. Embryology was the darling of biology for much of the 19^th century and journals like Wilhelm Roux’ Archives fuer die Entwicklungsmechanik der Organismen (later Rouxs Archives of Developmental Biology) from Germany, the Journal of Experimental Zoology in the US,  and the Quarterly Journal of Microscopical Science in the UK (which split eventually into the Journal of Cell Science and Development) were their avatars.

There seemed to be a lot of promise thatevolution could be explained from the viewpoint of an embryologocal dogma propounded by Ernst Haeckel: technically it is goes  something like “ontogeny recapitulates phylogeny.”  This means basically that the embryo in its development shows traces of  its evolutionary forebears as it grows.

For example, the organization of the early spinal column resembled certain aquatic creatures, and some thought that gill slits among embryos, or structures like them, were a commonality as well.

Moreover embryos from many vertebrates show great communality at similar stages of development, even if they later become structurally quite distinct.

However, Haeckel overreached and some of his explanations (and especially some of his accompanying illustrations) in scholarly publications clearly stretched the truth, or at the very least, were unable to be seen and similarly intepreted by others in good faith attempts to do so.

Eventually, the science of embryology evolved along different lines, and became a branch of genetics, in the sense that the first expression of the gene was likely to be revealed in how it directed the fate of the cells and tissues in embryos.

Whereas as before, one operated surgically on the embryo to see what would happen, the embryologists tried to determine what breeds or alterations in  gene sequences would lead to differences in the embryo.

In a sense, when embryology turned into “Developmental Biology,”  it regained some of its cachet by coming over wholeheartedly to the more reductionist, molecular-cellular side.

Indeed the field greatly reduced its work with vertebrate embryos (mostly amphibians and chicks) for what would become one of the workhorses of classical genetics: the house fly, and  other invertebrates. These creatures would multiply quickly for tests of genetic variation and/or to determine the embryonic results, obtained by exposing the starting material to genetic mutagens like x-rays or certain chemicals. 

It is no surprise that, to a great degree, the term embryology largely disappeared from journal titles, and the leaders for much of the past decade have had  names like Genes & Development (from Cold Spring Harbor Press. where the Watson of DNA fame settled down), Developmental Biology and the red hot member from the Cell Press family: Developmental Cell.

But there was a fly in the ointment of purely genetic explanations, because a number of things came to light that upset straightforward reductionism.

The first was the discovery of a family of genes called HOX. They exist to lay out the overall body plans for organisms  during the embryonic stage (of both vertebrates and invertebrates, and likely even in plants,.

Initial sequencing sequencing of these HOX genes showed that they were not all that different among evolutionarily related species, and even among some species not so closely related. 

But since these organisms all turned out quite differently, reductionists reasoned, should there not have been more variation? The idea was that a complete genomic sequencing would settle everything, after all did not one gene essentially do one specific job?

Secondarily, to their dismay, the fully sequenced genomes of disparate organisms were far less directly distinct and  informative than was supposed. Conventional genetically based evolutionary theory would have predicted much more delineation, even if some similarities remained.

Thirdly, evolutionarily-related species with very similar genomes often had very real differences in the duration and timing of embryonic development.

Indeed, in some species with very similar genomes, larval or embryonically less developed species live side-by-side with more fully developed relatives in the same environment, a factor that helps them coexist, perhaps by allowing them to competing for different resource at the same time, or by competing for the same resources, but at different times of year.

Finally, there was just no way of explaining away morphological similarities that were indeed incredibly complex, for example, how crania are shaped, or how limb development occurs, without some reference to both larger-than-molecular forces like fluid mechanics and weight-bearing , and to environmental forces like diet, temperature, and the presence or absence of competing members of a litter or predators.

In other words, factors that came into play in the explanation of morphological traits in the classic embryonic and adaptational anatomical  tradition had to be accommodated better, ideally without throwing out the last 40 years of progess in molecular and cellular genetics!

New concepts have evolved like the developmental-genetic toolkit, where the body plan is conserved and expressed on a resource-contingent basis. What is expressed, gets expressed, if and only if there is sufficient material for the organism to progress.

Furthermore, the one gene: one protein: one structure or one function model is clearly inadequate to explain morphological devolopment.

There has to be multipurpose roles of the same evolutionarily conserved genes and proteins especially in the light of other genetic advantages that encourage adaptive response to the body’s internal and external environment even though that does sound Lamarckian.

So, we now see a Renaissance in both evolution and in developmental biology, through a new synthesis that has taken on the catchy name and cachet of: “Evo-Devo!”

Tony Stankus, [email protected] Life Sciences Librarian & Professor

University of Arkansas Libraries MULN 223 E

365 North McIlroy Avenue

Fayetteville AR 72701-4002

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