[biomed] [tt] Gastric 'condoms' could help obese avoid surgery - tech - 02 February 2009 - New Scientist

[Brian Atkins]

Teflon gut

http://www.newscientist.com/article/mg20126936.300-gastric-condoms-could-help-obese-avoid-surgery.html?DCMP=OTC-rss&nsref=online-news

GASTRIC surgery is a last resort for people who are dangerously obese. But there 
may soon be a gentler option in the shape of a removable device inserted into 
the gut though the mouth.

The EndoBarrier, developed by GI Dynamics of Lexington, Massachusetts, is an 
impermeable sleeve that lines the first 60 centimetres of the small intestine. 
In animal experiments and preliminary human trials, it reduces weight and 
rapidly brings type II diabetes under control.

Given the rising tide of obesity across the developed world, new treatments are 
a matter of priority. In the US alone, more than 15 million adults meet the 
criteria for gastric surgery because they have a body mass index of more than 
40, or a BMI of 35 plus a complication such as diabetes.

While the operations do cause dramatic and sustained weight loss, their high 
cost and concerns about the risk of dying on the operating table mean only a 
fraction of those who might benefit go on to have the surgery. According to the 
American Society for Metabolic and Bariatric Surgery, around 220,000 people in 
the US had gastric surgery for weight loss in 2008.

GI Dynamics is not the only company working on alternatives (see "Wired for 
weight loss"), but its approach is appealing for its simplicity and low cost. 
The device, enclosed in a capsule, is inserted via the mouth using an endoscope. 
Once in place below the base of the stomach, the capsule releases a small ball 
that with the help of a catheter pulls a flexible sleeve made of the slippery 
polymer PTFE through the intestine. The ball is jettisoned and the sleeve fixed 
in place by releasing a spiked attachment made from the shape-memory metal alloy 
nitinol (see diagram).

The entire process takes less than half an hour, and the EndoBarrier can also be 
removed in less than 10 minutes by tugging on a drawstring to collapse the 
attachment device and pull out the spikes. The EndoBarrier is then pulled back 
out though the mouth.

At the Massachusetts General Hospital in Boston, a team led by 
gastroenterologist Lee Kaplan has shown that a miniature version of the sleeve 
causes weight loss in rats equivalent to a popular form of gastric surgery in 
humans, where food intake is restricted by an adjustable band placed around the 
top of the stomach (Obesity, vol 12, p 2585).

"We aren't doing anything to the stomach, so the patient can still eat 
normally," says Stuart Randle, president of GI Dynamics, who adds that some 
patients given gastric bands find ways to fulfil their cravings for more 
calories. "They can do a lot of creative things - basically putting food into 
blenders," he says.

Kaplan's team also found that the device caused a rapid reversal of type II 
diabetes, even before the weight loss kicked in, thought to be the result of 
changes in neural and hormonal signals sent from the gut. This also happens in 
patients given a gastric bypass, in which the gut is replumbed to miss out a 
large part of the stomach and part of the small intestine.

The weight loss triggered by the device is larger than can be explained simply 
through reduced absorption of nutrients, Kaplan adds. So that, too, seems to be 
driven mainly by changes to gut physiology.

Around 150 people have tested the device, with similar effects to those seen in 
rats. Randle says the total cost of the EndoBarrier, including installation and 
removal, will be around $7500. This compares to $15,000 or more for inserting a 
gastric band, or at least $20,000 for a gastric bypass.

More extensive trials will be needed to ensure the device is effective and can 
safely be left in the gut for long periods, says David Flum, who studies the 
outcomes of gastric surgery at the University of Washington in Seattle. "We 
don't really know what the implications will be."

But if the studies prove successful, many more obese people could have access to 
potentially life-enhancing weight loss treatment.

-- 
Brian Atkins
Singularity Institute for Artificial Intelligence
http://www.singinst.org/
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