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Sitting up straight is best for your back?
THE FACTS sit up straight, parents tell their children. It’s a well-known refrain, repeated through generations and based on the theory that anything other than a 90-degree posture places undue strain on the back. Despite its persistence, that advice is wrong. Parents may insist that sitting up straight with your thighs parallel to the ground is the best way to sit, but a long list of studies has shown that that position increases stress on the lumbar disks in your lower back.
Thirty years ago, scientists first showed this by inserting needles into the backs of volunteers and measuring the amount of pressure created by various seating positions. They found that a reclining position was ideal, placing the least strain on the back and minimising pressure that could lead to back problems. Since then, multiple studies have confirmed that finding. But it was only in 2006 that scientists produced direct visual evidence.
In a study that used new magnetic resonance imaging machines that allow people to sit instead of lie down, a team of researchers at the University of Aberdeen in Scotland looked at 22 volunteers who sat in three positions. The first two positions, sitting upright and sitting with the body hunched forward, produced the greatest spinal disk movement, causing the internal disk material to misalign. The third position, in which the subjects reclined at a 135-degree angle with their feet planted on the floor, created the least strain.
According to the study, any position in which a person leans back, opening the angle between the thighs and the back is preferable to sitting up straight. So Sitting upright at a 90-degree angle strains your back; leaning back places less pressure on the spine.
The real value of animal experiments is questioned today by a team of senior scientists who found that many are flawed and do not predict how well a prototype medicine will work in humans.
The news paper, published by the British Medical Journal, is likely to be seized on by the animal rights lobby as substantiation for their case to stop all experiments. Their case was bolstered by the disaster of the Northwick Park clinical trial, where a drug that had been safe in animals had catastrophic side-effects in the human volunteers. But the BMJ authors say the jury is out - it is not yet possible to determine how useful animal trials are because at present the methodological standards are poor.
“Sadly you can't say anything in this area without it being used politically by one or other interest group," said Professor Ian Roberts of the London School of Hygiene and Tropical Medicine, one of the authors. "But this paper is neither saying they are not good nor that they are bad." That judgement could not be made, because of the poor standard of much of the work.
The British public has consistently said in polling that it supports animal tests if they help human healthcare, there is no alternative and no unnecessary suffering to the animals, he said. The first question was one for scientists to answer - and this was the first attempt to take a rational look at the results of animal trials to see whether they predicted how well different drugs would work in humans.
The team looked at six drugs - two for stroke, and one each for head injury, haemorrhage, neonatal distress and brittle bones. They looked at results of the human clinical trials and then at the animal trials that had been carried out first.
They found that the results of the animal and the human trials were often different. Animals given corticosteroids after a head injury appeared to benefit, but when the drug was tried in humans, it did not help their recovery. Professor Roberts pointed to a major methodological flaw, however - rats were given corticosteroids just five minutes after their head injury.
The animal results for a drug called tirilazad for stroke were positive, but when the drug went into human trials, doctors found it actually increased the numbers who became dependent or who died. The paper, by Pablo Perel and colleagues, all from the London school, says of the 18 animal trials that "the quality of the experiments was poor". Some of the animal studies were inconclusive, but in two cases, in osteoporosis (brittle bones) and neonatal respiratory distress, where babies struggle to breathe, they came up with the same result as the human trials.
The authors call for more systematic reviews like this one, where the results of a number of animal trials are pooled so that researchers can get a clearer idea of the effects of drugs.—Dawn/The Guardian News Service
Men who take a drug to reduce hair loss may also be reducing their levels of P.S.A., a marker for prostate cancer. That may sound like a good thing, but while the drug lowers the level of P.S.A., it does not lower the risk of cancer. In fact, a new study reports, doctors could be misled into concluding that a patient’s risk is lower than it really is. Writing in The Lancet Oncology, researchers said the drug they looked at, finasteride, could halve the blood levels of P.S.A., or prostate-specific antigen.
The drug is sold under the name Propecia when it is used to treat hair loss. The study was conducted by Dr. Anthony V. D’Amico of Brigham and Women’s Hospital and Dr. Claus G. Roehrborn of the University of Texas Southwestern Medical Centre. Because many men consider hair-loss medicines to be “lifestyle drugs,” Dr. Roehrborn said, they often neglect to mention them to their doctors.
But even if they do, it might not make a difference. “The doctor may just write it down and not put two and two together,” Dr. Roehrborn said. Doctors look at P.S.A. levels, and how they change, to determine whether a patient may have cancer. If the level is high enough, they take a biopsy. Finasteride is used in larger doses for men who have swelling of the prostate, and is then known as Proscar. It was already known that these higher doses of finasteride lowered PSA levels, and for prostate patients taking the drug, doctors are advised to double the PSA level to have an accurate reading. But the study found that even at dosages one-fifth of those used to treat the prostate, finasteride lowers P.S.A. levels.
They based their findings on a review of more than 350 men taking it. On the other hand, if a patient is taking the drug and then stops without his doctor’s knowing about it, his P.S.A. level may spike up, prompting unnecessary concern.— Dawn/The New York Times News Service
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