Monday, October 08, 2007

Scientists discover purpose of appendix

Evolutionists used to upset creationists by calling it a "vestigial" organ but that was itself a leap of faith -- faith in the completeness of their own knowledge. Being myself a REAL atheist, I am pleased to see that the appendix may be functional after all.

Some scientists think they have figured out the real job of the troublesome and seemingly useless appendix: It produces and protects good germs for the gut. That is the theory from surgeons and immunologists at Duke University Medical School, published online in a scientific journal this week. For generations the appendix has been dismissed as superfluous. Doctors could find no function for it. Surgeons removed them routinely. People live fine without them.

And when infected the appendix can turn deadly. It becomes inflamed quickly, and some people die if it is not removed expeditiously. Two years ago, 321,000 Americans were hospitalised with appendicitis, according to the Centres for Disease Control and Prevention.

The function of the appendix seems related to the massive amount of bacteria that populates the human digestive system, according to the study in the Journal of Theoretical Biology. More bacteria inhabit the typical body than human cells. Most of the bacteria are good and help digest food. But sometimes the flora of bacteria in the intestines die or are purged. Diseases such as cholera or amoebic dysentery would clear the gut of useful bacteria. The appendix's job is to reboot the digestive system in that case. The appendix "acts as a good safe house for bacteria," said Duke surgery professor Bill Parker, a study co-author.

The location of the appendix, just below the normal one-way flow of food and germs in the large intestine in a sort of gut cul-de-sac, helps support the theory, he said. Also, the worm-shaped organ outgrowth acts as a bacteria factory to cultivate the good germs, Parker said. That use is not needed in a modern industrialised society, Parker said. If the gut flora dies, they usually can be repopulated easily with germs picked up from other people, he said.

But before dense populations in modern times and during epidemics of cholera that affected a whole region, it was not as easy to grow back that bacteria, and the appendix came in handy. In less developed countries, where the appendix may be still useful, the rate of appendicitis is lower than in the United States, other studies have shown, Parker said.

The appendix, which is about six to 10 centimetres long, may be another case of an overly hygienic society triggering an overreaction by the body's immune system, he said. Even though the appendix seems to have a function, people should still have them removed when they are inflamed because it could turn deadly, Parker said. About 300 to 400 Americans die of appendicitis each year, according to the CDC.

Five scientists not connected with the research said that the Duke theory makes sense and raises interesting questions. The idea "seems by far the most likely" explanation for the function of the appendix, said Brandeis University biochemistry professor Douglas Theobald. "It makes evolutionary sense." The theory led Gary Huffnagle, a University of Michigan internal medicine and microbiology professor, to wonder about the value of another body part that is often discarded: "I'll bet eventually we'll find the same sort of thing with the tonsils."



This is a pretty good study but is far from conclusive. The short time period of the intervention (1 year) and a possibility of restricted range are considerable limitations. It seems likely that even the "unhygeinic" Finns were still pretty hygeinic (restricted range) and one year of low exposure to pathogens may not matter much in terms of overall exposure. Popular summary below followed by abstract

The idea that an increase in allergies and asthma is a result of a reduction in childhood infections seems not to hold up, researchers report. Preventing common respiratory infections and stomach infections in child daycare centres had no impact on the later development of asthma, nasal allergies or eczema, according to a follow-up survey conducted 12 years later.

The findings do not support the "hygiene hypothesis," which theorises that reduced exposure to infections in childhood leads to greater allergic sensitisation, conclude Dr Teija Dunder and colleagues from the University of Oulu, Finland. The magnitude of the reduction in early infections "should have led to an increase in asthma rates if the hygiene hypothesis were to apply to common childhood infections," Dunder and colleagues point out in the Archives of Paediatrics and Adolescent Medicine for October.

Between 1991 and 1992, a total of 1376 children attended daycare centres that were either part of a hygiene intervention effort or not. The intervention included several steps, the most important of which was improvement of hand hygiene using an alcohol-based hand rub, the authors note. Children attending hygiene intervention centres had 15 per cent fewer days with symptoms of infections and 24 per cent fewer prescriptions for antibiotics than those attending "control" daycare centres.

A follow-up survey of 928 adolescents who attended the daycare centres as young children showed no differences between the two groups in the development or severity of asthma, allergic rhinitis or eczema. Asthma was diagnosed in 48 of 481 adolescents from intervention daycare centres (10 per cent) and in 46 of 447 controls (10 per cent). Similarly, no difference was found in the number of children who had a diagnosis of other allergic diseases or who had reported such symptoms. The researchers conclude that this shows that a reduction in infections in children attending daycare centres can be achieved by simple infection prevention practices. "We can now say that it proved to be safe because it had no effect on later (allergic illness)."


Journal abstract follows:

Infections in Child Day Care Centers and Later Development of Asthma, Allergic Rhinitis, and Atopic Dermatitis

By Teija Dunder et al.

Objective: To evaluate the effect of successful prevention of common infections in child day care centers on the later development of allergic diseases.

Design: Prospective follow-up survey with a questionnaire administered 12 years after a controlled randomized hygiene intervention.

Setting: Twenty municipal child day care centers in Oulu, Finland.

Participants: A questionnaire was sent to 1354 prior participants (98%) in the intervention trial. The response rate was 68% (928 of 1354 participants).

Main Intervention: Hygiene intervention from March 1, 1991, to May 31, 1992.

Main Outcome Measures: The number of respondents who had a diagnosis of asthma, allergic rhinitis, and/or atopic dermatitis made by a physician, and the number of those who reported symptoms of atopic diseases.

Results: Asthma was diagnosed by a physician in 48 of the 481 respondents (10%) from the intervention child day care centers, with markedly fewer infections, and in 46 of the 447 controls (10%) (relative risk, 1.0; 95% confidence interval, 0.7-1.4). Similarly, no differences were found in the numbers of children who had a diagnosis of other atopic diseases or who had reported such symptoms.

Conclusion: The prevention of common respiratory tract and enteric infections during early childhood does not change later allergic morbidity.

Arch Pediatr Adolesc Med. 2007;161:972-977


Just some problems with the "Obesity" war:

1). It tries to impose behavior change on everybody -- when most of those targeted are not obese and hence have no reason to change their behaviour. It is a form of punishing the innocent and the guilty alike. (It is also typical of Leftist thinking: Scorning the individual and capable of dealing with large groups only).

2). The longevity research all leads to the conclusion that it is people of MIDDLING weight who live longest -- not slim people. So the "epidemic" of obesity is in fact largely an "epidemic" of living longer.

3). It is total calorie intake that makes you fat -- not where you get your calories. Policies that attack only the source of the calories (e.g. "junk food") without addressing total calorie intake are hence pissing into the wind. People involuntarily deprived of their preferred calorie intake from one source are highly likely to seek and find their calories elsewhere.

4). So-called junk food is perfectly nutritious. A big Mac meal comprises meat, bread, salad and potatoes -- which is a mainstream Western diet. If that is bad then we are all in big trouble.

5). Food warriors demonize salt and fat. But we need a daily salt intake to counter salt-loss through perspiration and the research shows that people on salt-restricted diets die SOONER. And Eskimos eat huge amounts of fat with no apparent ill-effects. And the average home-cooked roast dinner has LOTS of fat. Will we ban roast dinners?

6). The foods restricted are often no more calorific than those permitted -- such as milk and fruit-juice drinks.

7). Tendency to weight is mostly genetic and is therefore not readily susceptible to voluntary behaviour change.

8). And when are we going to ban cheese? Cheese is a concentrated calorie bomb and has lots of that wicked animal fat in it too. Wouldn't we all be better off without it? And what about butter and margarine? They are just about pure fat. Surely they should be treated as contraband in kids' lunchboxes! [/sarcasm].

Trans fats:

For one summary of the weak science behind the "trans-fat" hysteria, see here. Trans fats have only a temporary effect on blood chemistry and the evidence of lasting harm from them is dubious. By taking extreme groups in trans fats intake, some weak association with coronary heart disease has at times been shown in some sub-populations but extreme group studies are inherently at risk of confounding with other factors and are intrinsically of little interest to the average person.


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