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  • Why are peanut allergies suddenly becoming more common in North America than elsewhere in the world?

    Posted on December 1st, 2010 admin No comments

    Nobody gave the answer I was looking for.  The answer from @jchaager is probably at least partly correct:  “Parents are raising their kids in a bubble and preventing early exposure to allergens that would build up their immunity.”

    The “overprotective parents” hypothesis (or “hygiene hypothesis”) of increase of allergies is probably at least partly true, but doesn’t lend itself to experimental verification.  What parent would agree to raise their child in “dirty” conditions for experimental purposes?  Nevertheless, there is some anecdotal support of the idea.  On the other hand, there is also experimental support of the idea that exposing a child to an allergen too early may trigger an allergy rather than boost their tolerance.

    Anyway, there is a biochemical and cultural cause that is hypothesized as a reason for increased peanut allergies in North America.  In North America, most peanuts are roasted, rather than boiled.  Boiling, as done in most of the rest of the world, neutralizes some allergens in peanuts.

    One of the main allergens in peanuts is “Ara h2,” which inhibits protein digestion.  Roasting peanuts makes this protein more effective at blocking protein digestion.  Thus, once a person with peanut sensitivity ingests Ara h2, other undigested proteins in the peanuts cause further allergic reactions.  Boiled or raw peanuts have less effective Ara h2, so are far less likely to trigger allergic reactions than roasted peanuts.

    More specifically, Ara h2 inhibits the action of the enzyme trypsin in the digestive system, which normally breaks down the peptide chains in proteins, liberating the component amino acids.  These undigested peptides are thought to be a contributor to the abdominal symptoms of peanut allergies.

    More about peanut allergies:

  • What human disease was caused by the rapid spread of corn throughout the world in 18th century?

    Posted on November 24th, 2010 admin No comments

    First correct answer was from @mlv: Pellagra is a niacin deficiency disease caused by rapid spread of corn-based diet.

    Pellagra, a niacin deficiency, was caused by the rapid spread of a corn-based diet and by improper preparation of the corn.  Traditional preparation of corn included soaking in alkali.  This released the niacin and prevented pellagra.  When Europeans spread corn from the Americas to other parts of the world, and it became a staple of many impoverished populations, they failed to spread the cultural traditions that made the corn a properly nutritious staple food.

    Note that pellagra is not caused by corn in the diet, but is not prevented by a nearly exclusive diet of corn.  It’s a matter of balance.  Anyone can certainly eat corn without fear of niacin deficiency, but if their diet includes no other significant source of niacin, they may be in trouble.

    Modern strains of corn have been selected to make niacin more accesible to digestion without alkali processing.

    Pellagra is still a problem in some refugee populations where corn is provided as an unfamiliar new staple food.

    More about pellagra:

  • What is the term for a lab test to determine whether a bacterial infection is resistant to antibiotics?

    Posted on November 4th, 2010 admin No comments

    First correct answer was from @cakTo:  The test to determine whether a bacterial infection is resistant to antibiotics is a “disc diffusion test.”

    The test is a disc diffusion test.  The result is called an “antibiogram.”

    To perform a disc diffusion test, first a culture of the infecting bacteria is grown in a Perti dish.  Discs of paper containing various antibiotics are placed on top of the culture to see which ones kill the bacteria and which don’t.  The degree of sensitivity of bacteria to the antiobiotic diffusing from the discs is measured by how far from the disc the bacterial die.

    An image of the results of the diffusion test is called an antibiogram.  It is used to plan treatment for the infection.  Whichever antibiotic is most effective against the bacteria in this particular infection is used to treat the infection.

    Disc diffusion tests take time, as it takes time to grow the culture, then more time to allow the various antibiotics in the test to take their effect on the culture.  Therefore, doctors will first begin treating the infection with the “best guess” antibiotic for the infection, then switch to another antibiotic as indicated by the antibiogram.

    Generally, an infection picked up “in the wild” will be treated with general-purpose antibiotics and no disc diffusion test will be performed.  Ironically enough, an infection aquired in a hospital is more likely to be resistant to common antibiotics, and so a disc diffusion test will be ordered.  If a hospital is experiencing an outbreak of an antibiotic-resistant infection among its patients, the doctor will begin treatment with whatever antibiotic was indicated in tests of earlier patients rather than beginning with general-purpose antibiotics.

    Of course, if an infection does not respond to general antibiotics will be followed up with a disc diffusion test, regardless of where it was aquired.

    More about disc diffusion test:

  • What fish produces a neurotoxin which some researchers claim to be part of the process of creating zombies?

    Posted on October 29th, 2010 admin No comments

    First correct answer was from @jrechs:  Blowfish (or pufferfish) produce a neurotoxin which hypothetically creates zombies.

    Tetrodotoxin (TTX) is a powerful and frequently fatal neurotoxin found in the flesh of the pufferfish (order Tetraodontidae).

    There is a hypothesis proposed by Dr. Wade Davis of Harvard University, an idea that is not universally accepted, that Haitian Vodou practitioners create “real zombies” using TTX and other toxins.  According to this hypothesis, the victim enters a near-death state, is buried, then reanimated as a slave of the zombie-maker.  Part of this hypothesis is that the “reanimated” victim is psychologically predisposed to behave as a zombie due to cultural beliefs.

    Many victims of accidental TTX poisoning, mostly in Japan where pufferfish is sometimes eaten, report that they remained fully aware of what was going on around them, able to hear, and sometimes even to see, when they were thought to be in a deep coma or near death.  This is consistent with the reports of some Haitian “zombies,’ saying that they were aware of who was at their funerals, they remember being buried, and that the vodou practitioner later exhumed and revived them to be slaves.

    Some critics claim that Davis might be a bit too gullible in taking the “zombies'” claims too seriously.

    More about pufferfish and zombies:

    Here’s an additional link from the pufferfish perspective:  Thanks to @stenoomen for the link.

  • What is a leading killer of bats in northeastern North America, threatening species with extinction?

    Posted on October 26th, 2010 admin No comments

    First correct answer was from @KessCat (@KessBat?):  Bats in northeast North America are dying from a mysterious white fungus.

    The “white nose syndrome” fungus is killing whole roosting colonies of bats, threatening some populations with extinction.  White nose syndrome got its name from white fungal growth on the muzzles and wings of infected bats.  The fungus is called Geomyces destructans.

    White nose syndrome has been found in bat colonies from Oklahoma and Tennessee to Ontario and Quebec.  The fungus only grows in cold conditions, so it kills bats while they hibernate.

    It is not certain that the “white nose syndrome” fungus is the direct cause of mass bat fatalaties, or an opportunistic infection that grows on bats that are already terminally sick.

    “White nose syndrome” fungus has also been identified in bats in France, but they were not sick.  There are interesting implications.  This may mean that white nose syndrome originated in Europe, and European bats have some resistance to it.  It may also mean that white nose syndrome is not the actual cause of these mass deaths, and the actual cause is not present in Europe.

    More about white nose syndrome:

  • What is the name for small protrusions on the tongue, many of which contain taste buds?

    Posted on October 8th, 2010 admin No comments

    First correct answer was from @AvenSarah:  The small protrusions on the tongue are called “papillae.”   There are 4 different kinds.

    1. Fungiform papillae are small mushroom-shaped protrusions on the tongue.  There are many throughout the tongue, holding some taste buds.
    2. Foliate papillae are small flattened protrusions on the tongue.  They are especially concentrated on sides of tongue near base, and each has many taste buds.
    3. Vallate papillae (also called “circumvallate papillae) are large dome-shaped protrusions near the back of the tongue.  There are only a dozen or so of them, each containing many taste buds.
    4. Filiform papillae are small protrusions on the tongue used for “grip” or rasping.  They contain no taste buds.

    Singular of “papillae” is “papilla.”

    More about papillae:

  • What is an epizootic?

    Posted on September 29th, 2010 admin No comments

    No correct and complete answers to this one.  An epizootic is an outbreak of disease among animals that exceeds the “expected” rate.  Partial credit to @mlv:  He missed the part that an epizootic applies to specifically to animals. Without that stipulation, the same definition fits “epidemic.”

    In common usage, we call a large outbreak of disease within a population of animals an “epidemic,” but that is technically incorrect.  An epizootic is an epidemic among animals.  Etymologically, an “epidemic” applies to people.  Animals aren’t people, by most definitions.   The word “epizootic” is derived from Greek, epi (“over,” or in this case “upon”) and zoion (“animal”).  Similarly, an “epidemic” is “upon the people.”

    Of course, etymologically, the term “population” should apply only to people, but I’m not aware of a synonym for animals or plants.  We refer to a “population” of animals or plants, but the word “population” derives from Latin populus (“people”).

    An extremely large outbreak of disease affecting an entire species (not just one population) is a panzootic (or a pandemic for such an outbreak among people).

    The words “epizootic,” “epidemic,” etc. once were applied only to communicable diseases, but are now often applied to any disease.  We speak of an “epidemic” of heart disease among post-industrial populations, even though it is not contagious.

    A note on pronunciation:  in “epizootic,” pronounce both o’s, the first one as in “goat,” and the second as in “otter.”

    More about epizootics:

    And about epidemics:

  • What disease normally associated with dogs caused a serious decline in lion populations in the Serengeti in 1990s?

    Posted on September 23rd, 2010 admin No comments

    First correct answer was from @KessCat:  Canine distemper wiped out about 30% of the Serengeti lion population in the 1990s.

    The outbreak of canine distemper virus (CDV) among lions was especially severe in the Ngorongoro Crater.  Various sources cite various figures, but one suggests that the 1994 CDV outbreak reduced the Ngorongoro lion population from 100 to 29.

    The Ngorongoro Crater population of lions is largely isolated and subject to inbreeding.  Ironically, a disease outbreak in 1962 enabled male lions from outside to enter Ngorongoro Crater, replenishing the gene pool.

    More about CDV and lions:

    Other specific references to the Ngorongoro lions:

  • We often hear that ice cream is thickened with extracts from seaweed. What cheaper source is replacing it?

    Posted on September 10th, 2010 admin No comments

    This question was more confusing than I expected.  Carageenan is a widely used thickener extracted from seaweed, but not the one I meant.  (See, I hit on an inspiration for a question, but forgot the broader context.  Yes, carageenan is the most frequently used thickener in ice cream, and it is still extracted exclusively from brown algae.)

    Alginic acid, also called algin or alginate, is also extracted from seaweed and used as a thickener, and also for other purposes.  It is algin which is also being produced by a cheaper process that does not involve seaweed.  It’s produced by bacteria.  Commercial quantities of algin are being produced by cultures of bacteria of genera Pseudomonas and Azotobacter.

    Algin is used as a thickening agent and emulsifier in foods, especially in its salt forms, sodium alginate and potassium alginate.  Algin salts are also used to produce gels for pharmaceuticals.  Next time you take antibiotic gelcaps, they may be made by bacteria.

    And if you don’t like the idea of seaweed in your ice cream, don’t worry about it!  It might be bacteria instead.

    More about bacterial algin:

    And some info about carageenan:

  • What is the connection between lacquer and poison ivy?

    Posted on August 24th, 2010 admin No comments

    First correct answer was from @KessCat:  The varnish tree is in same family (same genus, in fact) as poison ivy.  The first really complete answer was from @Gday_Cate:  The “active ingredient” (urushiol) is the same in varnish and in poison ivy.  Uncured varnish causes “poison ivy” rash.

    The varnish tree (Toxicodendron vernicifluum) produces resin nearly identical to the urushiol of poison ivy (T. radicans).  Varnish tree lacquer can cause the same kind of rash that poison ivy causes (called “Toxicodendron dermatitis” or “Urushiol-induced contact dermatitis”).

    Once cured, lacquer is no longer capable of producing a rash.  Only the unpolymerized urushiol causes a rash.

    There are many natural polymers with similar appearance (when cured) that are called “lacquer,” “shellac,” or “varnish.”  Some natural “lacquers” and “shellacs” are made from various plants, insects, and other sources.  Only urushiol from the Indian, Burmese, and Chinese varnish tree causes “poison ivy” rash.

    Poison ivy could be used to make the same kind of lacquer as the varnish tree, but the art originated with Toxicodendron vernicifluum in India and China.

    More about lacquer and poison ivy:

    And more about the “poison ivy” rash: