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Last updated: May 12, 2012 1:27 am
The Gila monster of the south-western US has two claims to fame: it is one of only two poisonous lizards in the world, and its metabolism is extraordinarily slow, so it typically eats only once every couple of months.
Both characteristics have attracted attention from pharmaceutical researchers. Gila monster venom is a potential source of drugs. But so far it is the lizard’s sluggish metabolism that is turning out to be more useful to humanity, leading to new treatments for the pandemic of type-2 diabetes that is sweeping the globe in association with dietary changes and rising levels of obesity.
The key is a gut hormone called “glucagon-like peptide 1”, or GLP-1, which the body releases as soon as you start eating carbohydrates. The hormone alerts cells in the pancreas to secrete insulin to control glucose levels in the blood.
Although human GLP-1 might be a good treatment for type-2 diabetes, giving pancreatic cells an extra stimulus to raise the low levels of insulin that cause the disease, the natural hormone is broken down too quickly in the body to be a practical drug. So the pharmaceutical industry needed to make GLP-1 last much longer in patients – which is where the Gila monster comes in. Reptilian GLP-1, released when the lizard starts to eat one of its rare meals, lasts for many hours, compared with a few minutes for the human hormone.
John Eng of the Bronx Veterans Administration Medical Center in New York was the first to isolate GLP-1 from Gila monster saliva. Amylin, a US biotech company, led the way in turning his discovery into a drug (exenatide), and others have followed, using chemical modifications to improve the pharmaceutical properties.
With more than 250 million people worldwide suffering from type-2 diabetes and projections suggesting that the total may reach 550 million by 2030, the need for an effective treatment is immense. The few old drugs available, notably metformin, perform poorly.
Clinical trials of the latest drug derived from Gila GLP-1, lixisenatide from Danish company Zealand Pharma, suggest that it not only lowers blood sugar levels but also helps patients to lose weight. This is because it acts on the stomach and brain – reducing appetite – as well as on its primary target, the pancreas, says David Solomon, Zealand chief executive.
It is 90 years since Canadian scientists discovered that type-1 (juvenile onset) diabetes could be treated successfully with insulin injections. While the introduction of GLP-1 drugs cannot match the significance of the insulin discovery, they may turn out to be the most important development in diabetes treatment of the early 21st century. And all thanks to the slow digestion of the Gila monster.
The Fellows need more females
The annual list of new Fellows of the Royal Society, Britain’s premier scientific body, features 42 men and just two women. The appallingly low female representation, following the election of five women fellows in 2011 and 2010, and two in 2009, raises the question of whether sexism is at work in the selection of FRSs or whether the Royal Society is doing its best to find deserving women at a time when they are seriously under-represented in the senior ranks of British science.
Artificial hips wear out more quickly and need to be replaced sooner if patients do high-impact exercise such as running and football, according to a French study
The equivalent list of new members of the National Academy of Sciences, the US counterpart of the Royal Society, may provide a clue. This year the Nas elected 26 women among its 84 new members – 31 per cent, compared with 4.5 per cent for the Royal Society. (About 10 per cent of science professors in British universities are women.)
There is not enough difference in the structure and sex balance of science between the US and UK to account for the much larger number of women honoured by the Nas, which suggests that the selection process may be partly to blame.
The Royal Society elects fellows through an elaborate peer review process that culminates in a vote by existing fellows, who will have proposed all 700 or so of the candidates. The letters FRS after one’s name can give a huge boost to a scientific career, and anecdotal evidence suggests that, on the whole, men lobby more aggressively than women for inclusion in the candidates’ book and then for election to the fellowship.
The Royal Society does a good job funding younger women and no one doubts that its leaders would like to elect more female fellows. So it is time for the society to investigate its election process and look for new ways to identify and promote female candidates who may be less self-assertive and less well connected than male colleagues. As role models, more female FRSs would boost the cause of women throughout science.
When a bird brain shows the way to go
How birds navigate remains one of biology’s big mysteries. Part of the answer seems to be through detecting variations in the Earth’s magnetic field, but how this sense works – and where in the brain it is located – is far from clear.
Last month, researchers shot down a favoured theory that iron-rich cells in pigeons’ beaks were compass cells. They turned out to be specialised blood cells with no possible sensing function.
Now two scientists from Baylor College of Medicine in Houston have identified 53 cells in pigeons’ brains that respond to changes in the direction and strength of the magnetic field around them. The experiment was conducted in a pitch-black room shielded from the Earth’s magnetic field. Seven pigeons were held in place as the researchers varied an artificial field while recording the birds’ neuronal activity. A group of 53 cells in the brainstem showed a clear response.
If the observation, reported in the journal Science, is confirmed, part of the navigation mystery – where bird brains register magnetic sensations – may have been solved, but it will still not be clear how birds actually detect magnetic fields and where the magnetic map is stored. The Baylor scientists believe the 53 compass neurons are responding to signals from magnetic detectors in the pigeons’ inner ear and that the magnetic map resides in the hippocampus. But research into avian navigation still has a long way to go.
Venus in transit: last chance to spot planet
Next month, for the second and last time this century, astronomers will be able to witness a transit of Venus. The planet will move slowly as a black dot across the Sun’s surface – an event not visible again on Earth until 2117.
Although the transit cannot be described as a spectacular event, it has great historical resonance. For early astronomers from the 16th century onwards, predicting the passage of Venus across the face of the Sun was a key test of how well they understood the solar system.
By the 17th century, calculations had shown that transits occurred in pairs separated by eight years, with a gap of more than a century between pairs. The first astronomer to witness a predicted transit was Jeremiah Horrocks in 1639.
The 18th century was the great era of transit viewing. Edmund Halley proposed that astronomers should use the two events predicted for 1761 and 1769 – well after his death – to measure the distance between the Earth and the Sun. And indeed dozens of expeditions fanned out across the world to do just that, including James Cook’s viewing of the event from what is still called Point Venus in Tahiti.
The 2004 transit did not generate such noteworthy observations, nor will the one visible on June 5 (in the western hemisphere) and June 6 (in Europe, Asia and Africa). Perhaps its most useful function for today’s astronomers is to hone their understanding of the optical effects when a planet passes in front of its parent star. The slight dimming this induces is an important indirect method of finding extrasolar planets elsewhere in the galaxy.
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