Friday, August 03, 2007


This is another "damned if you do, damned if you don't" situation. Sun exposure also causes skin cancer so do you get cancer by saving yourself from MS? Fortunately, there is no reason to worry. The study below is on very small numbers and the twins concerned had presumably been reared apart so many other things could explain the differences observed. Maybe the twins who got more sun were raised in richer families (or vice versa) for instance.

I also noticed that statistical significance is not mentioned in the abstract. I wondered why. Given the small numbers, I thought I knew why. And so it was. The differences FAILED the .05 criterion for statistical significance so may well have been purely random. Crap epidemiology just rolls on and on

Childhood sun exposure influences risk of multiple sclerosis in monozygotic twins

By Talat Islam et al.


Objective: To address the role of childhood sun exposure on the risk of multiple sclerosis (MS) after controlling for genetic susceptibility, we investigated the association between sun exposure and MS comparing disease-discordant monozygotic (MZ) twins.

Method: Twins with MS were sought by yearly newspaper advertisements throughout North America from 1980 to 1992. Diagnosis was verified by updated medical documentation through 2005. This analysis was restricted to 79 disease- and exposure-discordant monozygotic twin pairs who had ranked themselves before 1993 in relation to each of nine childhood sun exposure activities. A sun exposure index (SI) was defined as the sum of those exposures for which one twin ranked higher than his or her co-twin. The SI difference within each twin pair was calculated by subtracting the SI value of the affected twin from the SI value of the unaffected twin (range -9 to +9). The results were then analyzed using conditional logistic models.

Result: Each of the nine sun exposure-related activities during childhood seemed to convey a strong protection against MS within MZ twin pairs. Depending on the activity, the odds ratio (OR) ranged from 0.25 to 0.57. For example, the risk of subsequent MS was substantially lower (OR 0.40, 95% CI 0.19 to 0.83) for the twin who spent more time suntanning in comparison with the co-twin. For each unit increase in SI, the relative risk of MS decreased by 25%.

Conclusion: Early sun avoidance seems to precede the diagnosis of multiple sclerosis (MS). This protective effect is independent of genetic susceptibility to MS.

Source. Fuller report here

Zebrafish study may point way to blindness cure

The ability of zebrafish to regenerate damaged retinas has given scientists a clue about restoring human vision and could lead to an experimental treatment for blindness within five years.

British researchers said on Wednesday they had successfully grown in the laboratory a type of adult stem cell found in the eyes of both fish and mammals that develops into neurons in the retina.

In future, these cells could be injected into the eye as a treatment for diseases such as macular degeneration, glaucoma and diabetes-related blindness, according to Astrid Limb of University College London's (UCL) Institute of Ophthalmology.

Damage to the retina -- the part of the eye that sends messages to the brain -- is responsible for most cases of sight loss. "Our findings have enormous potential," Limb said. "It could help in all diseases where the neurons are damaged, which is basically nearly every disease of the eye."

Limb and her colleagues studied so-called Mueller glial cells in the eyes of people aged from 18 months to 91 years and found they were able to develop them into all types of neurons found in the retina. They were also able to grow them easily in the lab, they reported in the journal Stem Cells.

The cells have already been tested in rats with diseased retinas, where they successfully migrated into the retina and took on the characteristics of the surrounding neurons. Now the team is working on the same approach in humans. "We very much hope that we could do autologous transplants within five years," Limb told Reuters.

Autologous transplants, initially on a trial basis, will involve manipulating cells and injecting them back into an individual's own eye. Eventually, Limb hopes it will also be possible to transfer the cells between different people. "Because they are so easy to grow, we could make stem cell banks and have cell lines available to the general population, subject to typing as with blood transfusions," she said.

Just why zebrafish have an abundant supply of adult stem cells to regenerate their retinas, while they are rare in mammals, remains a mystery but Limb suspects it is because mammals have a limiting system to stop proliferation.

The new work on Mueller glial cells is the latest example of researchers exploring the potential of different kinds of stem cells in treating eye disease. Another team from UCL and Moorfield's Eye Hospital said in June they aimed to repair damaged retinas with cells derived from embryonic stem cells.



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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