Medescape

Skepticism, Medicine and Science News

Fat Busting Enzyme

Scientists have discovered a mutation in a roundworm that causes them to rapidly burn fat, and they say this could lead to new ways of treating obesity. The study was done at McGill University, and published in Nature

The roundworm in question is of the species Caenorhabditis elegans, a small creature only about 1 mm in length. When little food is available, they go into a sort of hibernation state called dauer. During this state they drastically alter their metabolism by shutting down energy consuming processes such as cell division and reproduction. As opposed to normal hibernation though, the worms are able to move around when in this state due to a special storage of lipids. This extra lipid reserve allows the worms to stay in the dauer state for as much as 6 months, which is considerably more than the estimated 2 weeks they would otherwise have managed. 

The newly discovered mutation in some of the ringworms has a considerable impact on their metabolism in dauer, and these worms were shown to die within a week of entering the state. The main reason for this is that they fail to regulate the catabolism of the lipid storage, and thus burn all of it within a few days. This is due to the lack of an enzyme that normally blocks the activity of an important triglyceride lipase, a class proteins that catalyse the hydrolysis of lipids and thus the catabolism of them. The thinking is that the regulating role of this enzyme may translate to humans, and that the faliure of this protein to function properly may lead to increased accumulation of triglycerides and thus lead to obesity. The researchers also believe that it may be possible to develop a drug that inhibits this regulatory enzyme specifically in fatty tissue, and in this way increase the catabolism of triglycerides and decrease patients weight.

It all sounds very similar to what we can achieve with uncoupling proteins. Most of a cells energy (in the form of ATP, or adenosin triphosphate) is generated in the mitochondria by using a generated proton gradient over the inner membrane. When these protons are brought back into the matrix of the mitochondria, they drive an enzyme that generates ATP from ADP (adenosin diphosphate) and a phosphate molecule. Uncoupling proteins are lipophilic proteins that bind to the protons in the intermembrane space and carry them over the inner membrane without driving the ATP-generating enzyme. This means that the energy from proteins, fats and carbohydrates disperses as heat, and is not used to generate energy that the cells can take advantage of. This could rapidly lead to an extreme shortage of energy, a potentially lethal state. One such uncoupling protein is 2,4-Dinitrophenol. Discovered in the 1930s, it is still used by some as a dieting aid and a quick and fast method of loosing body fat. This could cause serious problems though, such as hyperthermia and energy shortage. Not something I would advise taking. 

But, if a drug were developed that worked solely in fatty tissue and could be easily controlled, it could very well be extremely useful in treating obesity. 

Caenorhabditis elegans

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December 9, 2008 Posted by | 1 | , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , | Leave a comment

Teddies In Space

It sounds like a bad sci-fi movie from the 80s, but it is actually a really, really cool science project. Students at the University of Cambrige recently managed to put four teddy bears in space by using a weather balloon. The maximum altitude reached was about 30km, and to prevent the bears from freezing solid the students designed and built space suits for them to wear. This was really the main part of the project, and was an excellent way of teaching the students the principles of insulation, convection, conduction, radiation, pressure and loads of other exciting physics. Oh, and the students in question were actually aged about 11-12, and I think this is a wonderful way of getting young kids excited about science. I really hope other schools follow Cambridge’s example on this one. 

I mean, how cool is that!

December 8, 2008 Posted by | Astronomy, General Science | , , , , , , , , , , , , , , , , , | Leave a comment

Filming The Immune System

Scientists at Sydney’s Centenary Institute recently managed to film an immune cell in the process of being invaded by the parasite Leishmania. The study was published in PLoS Pathogens

This is the first time this process has been filmed, and it was made possible by using high powered multi-photon microscopy which allowed the cells to be viewed in real time. Using this technique, head researcher Wolfgang Weninger and his team were able to study dendritic cells in the skin after the introduction of Leishmania parasites. This ability to track pathogens in the immune system is likely to benefit vaccine research and other studies of the immune system in general. 

This image shows an immune cell absorbing the parasite via pseudopods. The parasite is shown in red, and the blue circles are vacuoles containing parasites.   

The full study can be found here, and there are some really cool videos included in “Supporting Information” part the article. I recommend taking a look at them.

December 7, 2008 Posted by | Biology, Medicine | , , , , , , , , , , , , , , , , , | Leave a comment

Medical Firearm

A US-based company,  Constitution Arms, claims to have received federal approval to market their most recent handgun as a medical device. It is a 9mm gun that cost about $300, and contrary to the company’s claims, the Food and Drug Administration (FDA) say they have not made any such approval. 

They call it the Palm Pistol, and it is intended for people who have trouble operating a normal handgun, like the elderly. As of yet the Palm Pistol is just a prototype, but the company president says they hope to start the manufacturing process soon. 

Now, I think it is perfectly fine to make a handgun that is easy for people with dexterity problems to use. There is certainly a market for it. However, to claim this is a medical device is just insane. Here is what the company president, Matthew Carmel, had to say about it:

It’s something that they need to assist them in daily living

Daily living? That is just absurd. I can see how it may give elderly people a bit more confidence when walking to the store for example, but I really don’t think it would help them much if they were to be robbed. If you cannot operate a normal handgun, what are the odds of you managing to fish this thing out of your bag in time to deter a would-be robber? Also, if the robber is armed, he/she will certainly be quicker on the draw than you, and trying to threaten him/her with this thing would most likely only get you shot. 

As mentioned, the company seems to have jumped the gun, no pun intended, a bit when it came to the FDA approval for selling the gun as a medical device. They actually claimed the FDA approved this as a “Daily Activity Assist Device”. You cannot help but wonder what exactly the elderly are supposed to be doing if their daily activities require the use of handguns.

December 5, 2008 Posted by | General Science, Medicine | , , , , , , , , , , , , , , , , , , , , , , | Leave a comment

Sneaky Cats

Evolutionary researchers at Duke University recently published a study where they investigate the differences in gait between cats and dogs, seen from an evolutionary point of view. What they found was that evolution seems to have take two entirely different paths. Dogs have a very energy-efficient style of running, so they can chase prey over larger areas without burning too much energy. Cats on the other hand have a much more inefficient gait, but it is perfect for slow movements, enabling them to sneak up on prey covertly. The study was published in the Public Library of Science.

In the study, Kristin Bishop, Daniel Schmitt and Anita Pai videotaped six housecats moving along a runway chasing food/toys++. They found that the cats were able to reduce the muscular work needed to move forwards by about 37%, while long-distance predators, like dogs, are able to reduce it by 70%. This suggest a trade-off for the cats where the ability to move stealthily evolved at the cost of more inefficient gait. 

Oh, and humans have about the same gait efficiency as dogs, ie about 70%. Hurray for bipedalism! 

December 4, 2008 Posted by | Biology, Evolution, Creationism and ID | , , , , , , , , , , , , , , , , , , , , , , | Leave a comment

The Placebo Gene

Most people are familiar with the placebo effect, and in general terms it is the therapeutic effect of an inert/ineffective treatment. People tend to get better just because they believe they will, and placebos are therefore used in double-blind trials as a way of eliminating the placebo effect from the final results. 

It is not really surprising that the effect is as substantial as it has been shown to be. Of course, a placebo will do you no good when treating a bacterial infection for example, but for non-specific, general symptoms such as pain, they tend to do very well. The perception of pain is highly regulated in the brain, and I’m sure everybody has experienced that the amount of pain felt varies greatly according to whether you know something painful is about to happen or not. 

Even though the placebo effect is well known and widely used in clinical medicine and research, it is not thoroughly understood. In a recent article though, scientists have managed to link a specific gene to increased susceptibility to the placebo effect. The research was done by researchers at Uppsala University in Sweden, and published in the Journal of Neuroscience. The study looked at 25 patients with social anxiety disorder, and over an 8-week period they recieved a placebo that they were told would help improve their condtition (of course, neither the patients nor the doctors knew the drug was a placebo). At the end of the period, a positron emission tomography (PET) scan was done and compared with one done 8 weeks prior. 10 of the patients responded to the placebo treatment, and 8 of these varied genetically from the others. The researchers found that these 8 had two copies of a particular G-variant of the gene that codes for tryptophan hydroxylase-2, an enzyme involved in the process of synthesizing the neurotransmitter serotonin. None of the other participants had two G-copies of the gene, and Tomas Furmark, lead scientist, believe the effect of this gene may extend to other phenomena associated with the amygdala, such as depression and pain disorders. 

The sample size of the study was not, however, very impressive, and the results would have to be externally replicated before any real conclusions could be made. Also, the general consensus is that there is no single placebo effect, but a lot of different mechanisms that together make up the whole, including genetic factors. Still, a nice advance in placebo research. Full paper can be found here.

December 3, 2008 Posted by | Medicine, Neuroscience, Psychology | , , , , , , , , , , , , , , , , , , , , , , , , , , , | Leave a comment

Body Swapping

Scientists at the Karolinska Institute in Stockholm have managed to create the illusion of “body swapping” in the lab. They were able to fool volunteers into perceiving the bodies of both mannequins and other people as their own by using CCTV cameras and physical stimulation. Pretty cool….

December 2, 2008 Posted by | Neuroscience, Psychology | , , , , , , , , , , , | Leave a comment

Like A Surgeon

Robotics have become a huge help when it comes to medical procedures, and are commonly, to a certain extent, used for example in procedures that require absolute precision. Swallowing mechanical devices are also not uncommon, generally in the form of a small camera that takes pictures of the gastrointestinal tract to help doctors locate ulcers/tumors and so on. One problem, or maybe disadvantage is more correct, with these cameras has up until now been that they are passive, ie they take pictures of what’s in front of them, and that’s about it. In a new publication by the Institute of Robotics and Intelligent Systems (IRIS) of ETH Zurich, researchers describe how we might design and engineer microrobots that would be able to play an active role in the body, maneuvering themselves to specific regions to take pictures and even tissue samples. 

One of their ideas is to fit a small robot with insect-like legs to help it navigate the gastrointestinal tract. This would enable doctors to actively control or preset the movement of the robot, and thus guide it to specific regions where they suspect the problem is. Another idea is to also fit the robot with equipment to obtain a tissue sample, something that would otherwise require an invasive procedure.

One of the major problems with this kind of application of robotics is naturally the size aspect. You can’t make the robot to big, or the patient will not be able to swallow it. One possible solution to this problem is to design the robot in a way that would enable self-assembly in the gut. This would mean that the patient could swallow three or four smaller pieces that would then assemble to form the complete robot in the stomach. Zoltan Nagy, a researcher with the IRIS, designed a system that used magnets to accomplish this self-assembly. The individual parts where polarized in a way that made them organize into a predictable structure once in the gut, and when tested, in an artificial stomach, this had about a 75% success rate. 

Another major problem is the power supply. Batteries make up about 60% of the size of today’s pill-cameras, and a lot more power would be needed to supply a robot capable of taking biopsies. Another problem is patient safety. No damage to the wall of the gastrointestinal tract should be done by the robot, and there would also have to be some mechanism of disassembling the robot at any time if something were to go wrong. 

Still, maybe some years from now this will be a reality. Full paper can be found here.

December 1, 2008 Posted by | Medicine | , , , , , , , , , , , , , , , , , , , , , , , , , , , , , | Leave a comment

Fast Food Advertising

A new study finds that banning fast food advertising during children’s TV-shows could reduce obesity in children ages 3-11 by 18%. In children ages 12-18 the effect would be less, about 14% according to the study. 

The study was published in the Journal of Law and Economics, and conducted by researchers from the National Bureau of Economic Research (NBER) with funding from the National Institutes of Health. The researchers used data from the 1979 Child-Young Adult National Longitudinal Survey of Youth and the 1997 National Longitudinal Survey of Youth, enabling them to assess the viewing habits of over 13,000 children.

The researchers pointed out that implementing a ban on advertising might not be the most practical thing to do. The only countries having this kind of ban against commercial sponsorship of children’s TV-shows are currently Norway, Sweden and Finland, and these countries have a much more of a tradition for government involvement in these kinds of matters than the US. Another solution might be to eliminate the tax deductibility that comes with advertising. Since advertising is considered an expense it reduces the company’s income and thus the amount of tax. Eliminating the deductibility would in effect mean that advertising would become about 54% more expensive, and even though it would be less effective than an advertising ban, it would still reduce by about 5-7%.

November 30, 2008 Posted by | Economics, Medicine | , , , , , , , , , , , , , , , , , | Leave a comment

Photons to Power Nanomachines

Photons are elementary particles and the basic units of light, and they are capable of exerting forces. Recently, this force was shown to be strong enough to power a small, mechanical resonator, in other words a proof of concept that may lead to a new way of powering nanoscale machines. The research was done by Hong Tang et al at Yale University. They designed and tested a device that was able to take advantage of the optical gradient force to create vibrations. The device channelled incoming light through an extremely thin passage, only about 110 nanometres wide, in a photonic circuit. This caused the material to resonate at right angles to the beam. Even though the force generated is extremely small, the researchers claim it is strong enough to power small-scale devices, and since light can easily be beamed at large areas at a time, several devices could be powered with little effort. 

A picture of the photonic circuit with one of the resonators highlighted. 

The full article can be found here.

November 29, 2008 Posted by | General Science, Physics | Leave a comment