Category: Online

The evolution of venom: Poison pill

Akshat RathiLeave a comment

The bite of a rattlesnake can, within minutes, cause paralysis and extensive internal bleeding. If untreated it can kill. It might also hold the key to treating high blood pressure, heart diseases and stroke. In 1998 two drugs to prevent heart attacks, derived from rattlesnake and viper venoms, were approved. Since then a number of other venom components have proved effective against some varieties of cancer and brain disorders like Alzheimer’s or Parkinson’s, but gaining regulatory approval has proved tricky. Part of the reason is that it is difficult to tweak toxins such that they preserve their medicinal effects but lose their nefarious ones, like stanching blood flow or numbing the nervous system.

Now, though, Wolfgang Wüster, of Bangor University, in Britain, and his colleagues have stumbled on an evolutionary mechanism that might make such modifications easier in future. Dr Wüster was investigating venomous snakes and lizards to understand what they had in common. They differ in many respects—most venomous lizards, for instance, have fangs in the lower jaw, whereas snakes have them in the upper jaw. But in 2005 Bryan Fry of Sydney University found that snakes and lizards in fact share venom-making genes, suggesting that both share a venomous reptilian ancestor.

Whereas Dr Fry looked only at selected venom-making genes, Dr Wüster had the luxury of complete genetic data for different snake and lizard species. This allowed him to check if venom-spitting reptiles possess other shared genetic traits, too. As he and his team report in Nature Communications, they do.

These include genes to produce enzymes that perform some basic physiological functions. Intriguingly, some of these housekeeping genes were sitting among venom-producing ones. Venom genes are known to have evolved from more innocuous sorts, but it was thought that all the genes in a particular stretch of DNA assumed the venom-producing function. To find some that did not, therefore, posed a quandary. Were the innocuous genes among the insidious ones simply evolutionary relics? Were they evolved versions of the original innocuous genes that, unlike their venom-producing neighbours, remained innocuous? Or did they in fact evolve from venom genes that had lost their venom-producing prowess?

To help decide the matter, Dr Wüster ran a computer model to trace the genes’ evolutionary histories. This revealed that the third scenario was the most likely. Moreover, it seems that certain housekeeping genes turned into venom-producing ones and back again several times in reptiles’ genetic past. This means that the venom-producing genes and the housekeeping variety nested among them are genetically similar. As such, they produce proteins which are themselves alike in many respects, but not necessarily in their ability to do harm.

Practical applications of this knowledge are not an immediate prospect. But by understanding what makes a venom protein venomous researchers may get a better idea of how to remove the unwanted sting. That is one trick drugmakers would love to be able to pull of.

First published on economist.com.

Image credit: The Economist

Visualising Facebook

Akshat RathiLeave a comment

Your correspondent was shocked to learn that 34% of his Facebook friends are married. Still in his 20s, he does not want to contemplate settling down quite yet. Knowing that 64% of his online friends are male does not help either—more so because only 57% of Facebook is comprised of women. When he lamented these facts (on Facebook of course) he was asked the obvious question: “Did you go through your friends list and count?”

Well, no. The number-crunching comes courtesy of Wolfram|Alpha, a sort of search engine for quantifiable facts. Begun in 2009 by Stephen Wolfram, a British scientist and entrepreneur, the online service serves up answers to queries by harnessing information from its own databases. It can compute things like the distance between the Earth and the Moon on your parents’ first Valentine dinner, for example. Its latest feature lets people analyse their Facebook account for free. Enumerating and plotting the vagaries of one’s online life is at times surprising. Your correspondent wouldn’t have thought he was many times more active in 2011 than this year, in terms of status updates, sharing links, photos, etc (chart below).

Since the service began a few weeks ago, more than 400,000 Facebook users have let Wolfram|Alpha examine their digital bits—an outpouring of interest that caught the firm by surprise, says Luc Barthelet, Wolfram|Alpha’s executive director. The company plans to expand into other “personal analytics” services. Mr Barthelet declined to be more specific, but it could well entail analysing users’ email patterns and other social media behaviour.

In February Wolfram|Alpha rolled out a Pro service. At $4.99 per month it gives people the ability to process their own data, or even download Wolfram|Alpha’s information on a query. Such information is potentially very useful as it comes from the service’s own curated databases. Thus, armed with data on homicides in African countries, for example, Wolfram|Alpha can generate various types of graphs (scatter plot, raw data plots, bivariate histograms) to help users understand their information better. It can create a heat map to visualise the data geographically. And it lets users overlay other data, such as GDP of the country, to make, in this case, a GDP-neutralised heat map.

The Wolfram|Alpha “answer engine” is based on Mathematica, a software program developed by Mr Wolfram that can perform elaborate calculations. After the site’s launch in 2009 it was criticised for being limited in what it could do: solve mathematical problems, answer some scientific questions, but nothing out of the ordinary. Since then it has expanded considerably. As it moves beyond computing the world into analysing the individual, it is providing fresh new ways to look at life.

Also published on economist.com.

Free image from here.

Circumcision: Snipped in the bud

Akshat RathiLeave a comment

IN 1999 the American Academy of Paediatrics (AAP) declared that although circumcision carries some health benefits, these do not outweigh the risks of giving a newborn lad the snip. Since then the number of circumcisions in America has fallen from 61% to 56% of baby boys, though it remains well above the global figure of about 30%. In 2007 the AAP set up a task force to update the recommendation. After poring over 1031 peer-reviewed papers, its experts reversed it altogether.

It has been known for a while that circumcision reduces the risk of HIV infection, because the immune cells under the foreskin are vulnerable to the virus. This has led to vastly more circumcisions being performed in AIDS-ridden parts of Africa. The AAP’s report revealed that circumcision is also associated with lower rates of infection with the human papillomavirus (HPV), which has been found to collect under the foreskin, and herpes simplex. Since cervical cancer in women is caused by HPV infections, circumcision has some protective effect on men’s female partners too. Nor did the task force find any evidence that circumcision lowers sexual function or pleasure. One study of 5,000 Ugandan men found not only that intercourse was less painful for circumcised men but that, two years after the procedure, they were in fact more sexually satisfied.

These benefits accrue to sexually active adults, not newborns or children, but Colleen Cagno, a paediatrician at the University of Arizona, points out that overall risk of complications is lower when circumcision is performed soon after birth. One reason might be that procedures carried out later on in life tend to involve general anaesthesia, which brings its own risks and which newborns are spared. In any case, circumcisions rarely go wrong in rich countries, where patients can expect proper medical care. In Israel only 0.3% of circumcisions lead to any complications. There is no overall figure for America, but just 0.2% of circumcisions result in “acute” complications.

The report finds that circumcision of newborns benefits them long before they reach sexual maturity. It reduces the risk of urinary tract infections (UTIs) in boys under the age of two. (UTIs are rare among toddlers, but the protection offered may be for life; almost half the male population will suffer from a UTI at least once in life.) The report’s authors also reckon that every 909 snips (that is, 0.1% of cases) will lead to one case of penile cancer averted. A cost-benefit analysis recently published in British Medical Journal finds that an average uncircumcised man will incur an additional $450 in health-care costs over a lifetime. This may not sound much, but it is an average; for some individuals the costs may be much greater.

If removing the foreskin brings so many benefits, why was the custom adopted in the first place? Brian Morris, a physiologist at the University of Sydney who together with colleagues reviewed the literature independently and came to the same conclusion as the AAP, thinks that the extra flesh may have played an important role in thwarting infections, acting as “nature’s underpants” when man lived in caves. In the modern, hygienic world, such paleolithic protection may be redundant. Or, as in the case of HIV and HPV, positively harmful.

According to the World Health Organisation circumcision is one of the most common medical procedures in the world. The AAP’s recommendations are coming up against millennia-old religious rituals (see article in the print edition). All the more reason that its call for the snip to be carried out only by trained professionals, using painkillers, and with parents’ informed consent, deserves attention.

First published on economist.com.