Wednesday, August 19, 1998

Link between stress and cancer
“The link between stress and cancer has not been conclusively proven, but a lot of experts feel it plays a decisive role. It is possible there is an indirect association,’’ Gavin Evans quotes an expert from West Scotland Cancer Surveillance Centre.

Maize as anti-cancer agent
In a major breakthrough, scientists have developed a genetically engineered maize strain capable of secreting human antibodies against cancer, a PTI report

Medical notes

How safe are mosquito coils and mats?
By G.V. Joshi

The growing menace of mosquitoes has forced people to turn to mosquito repellents in the form of body lotions, creams, coils and mats. For many families using a mat or lighting a coil is a daily ritual. Advertisements on TV promote the use of mats.

According to a study conducted by medical researchers working at the Indian Council of Medical Research (ICMR), New Delhi, coils and mats which use synthetic pyrethroids like allethrin, D-allethrin, D-transallethrin, bioallethrin and esbioallethrin are effective in controlling the mosquito menace and the fumes emitted by them are toxic for mosquitoes but safe for humans.

Proper use of coils involve a burning temperature of about 80° C. The smoke from coils deters the mosquitoes from entering the room, while those inside are expelled or their host finding ability is affected. A significant proportion of them are knocked down and killed. Mats are heated in an electrically heated gadget. A mat surface temperature between 80°C and 115° C is ideal.

Toxicologic studies at the ICMR indicated that the allethrin group of chemicals are metabolised in mammals rapidly and there were no reports of accumulation of these compounds in animal tissues. They are highly biodegradable and disintegrate in sunlight. There is no chance of their accumulation in the soil as well as plants. Their restricted use, mostly against mosquitoes and that too at very low concentrations, results in little or no chance of their residues in food.

However, a chemical used in these mosquito repellents is a nerve poison. It affects the nervous systems of mosquitoes. Many people are allergic to the vapours coming out of mats and do not use them.

Research abroad has already established that prolonged use of mats is harmful for several organs in the human body. It can lead to corneal damage, shortness of breath, asthma and even damage the liver in the long run. According to the Consumer Guidance Society of Mumbai, many chemicals used in mats can affect male as well as female fertility. It is preferable to use screens on windows or mosquito nets.

Allethrin was produced nearly 36 years ago in the USA. Over the years, extensive studies have been carried out in countries all over the world and there is a vast amount of data available on its effectiveness and safety. Rumours that it causes fever have no scientific basis.

Allethrin is less toxic than caffeine, if swallowed. A mosquito mat contains only about 40 milligrams of allethrin, which on slow evaporation gets dispersed in the air with no long-term effects.

Liquid drops sold in the market to make used mats reusable cannot do so, because the mat made of thick blotting paper loses its ability to uniformly absorb and release allethrin after its use. The drops may also contain other toxic chemicals.

The blotting paper used to make mats contains dioxin, an established cancer causing drug. Traces of dioxin emanate from the mat in the heating process.

According to Mr Narendra Wagle, a chemical technologist and chairman of the Consumer Guidance Society of India, allethrin affects human beings adversely, but very slowly , and the effect depends upon the weight of the person. There is no danger for heavy persons but light weight children may be affected. As of today no one has reported any adverse effects after long and sustained use of mats and coils daily.

According to another study conducted recently by Dr Devika Nag working at Kind George Medical College, Lucknow, mats and coils should be used only for a few hours at a time. Infants exposed to mats for a long time may get convulsions. Convulsions resulting from exposure to mats have been reported from China too. Detailed results of adverse effects of more long-term exposure are awaited. It was also found that the use of mats and coils aggravated the condition of chronic asthma patients.

— ANF

Link between stress and cancer
By Gavin Evans

THINK of all those tight-knickered city boys, burning and slashing their way through London, New York and Tokyo, pulling themselves ever higher by their own braces, and sneering at the resentful rest of us who pinch pennies for a living.

Then think of young Nick Leeson, 31, the best and worst of that breed, his money and his wife mere memories, holed up in a Singapore cell for bringing down Barings Bank, and recovering from an operation that removed a cancerous growth from his bowel.

Is cancer a consequence of his dramatic fall? Actually, it may not be the full explanation, because Leeson appears to be one of the 9 per cent of colon cancer sufferers whose condition is due to a genetic abnormality.

Generally colon cancer, which has a 45 per cent fatality rate, is triggered by diet. But patients may have a genetic predisposition. After 30 years of research, says Edinburgh University oncologist Prof John Smythe, “few years we’ll be able to identify the foods responsible and the people most at risk by screening their bowels.’’

However, there is reason to suppose a direct relation between trauma and bowel cancer. After all, conventional wisdom has long held that your state of mind is reflected in your gut. As St Thomas’s Hospital consultant gastroenterologist, Dr Jeremy Sanderson, puts it: “Stress tends to be expressed through the bowel, which is why you may get the squirts when going for an interview.’’

There’s evidence that severe stress, particularly if induced by traumatic loss (of status, job, wife, fortune and freedom, in Leeson’s case) can be a direct catalyst for a range of diseases, including asthma, constipation, diarrhoea, and high blood pressure, and indirectly for several others. The stress-blood-pressure link, for example, appears to be a potential factor in heart disease and strokes, both usually caused by blockages to key arteries.

Dr Peter Sandercock, senior lecturer in clinical neuroscience at Edinburgh University, says stress may exacerbate the risk of strokes. “The precise role of stress is debatable, but we can say that many of the conditions which accompany stress and a pressurised lifestyle, such as high blood-pressure, play a key role. Other than age, blood-pressure is the most important risk factor.”

Prof Charles Gillis, of West Scotland Cancer Surveillance Centre, says: “The link between stress and cancer has not been conclusively proven, but a lot of experts feel it plays a decisive role. It is possible there is an indirect association.’’

Others, like Professor Smythe, are more convinced. “It’s true there is no scientific proof, but there is a widespread assumption that psychological trauma is bad for cancer,’’ he says.

The link between stress and disease emerged clearly after Japan’s 1995 Kobe earthquake. Several studies found a clear connection between that trauma and hypertension, diabetes, kidney trouble, and anorexia nervosa. An American journal, Archives of Internal Medicine, reported this year a clear relation “between chronic, life-threatening stress and the worsening metabolic control in patients with diabetes mellitus.’’

—The Guardian, London

Medical scientists up in arms

A proposal by Ms Maneka Gandhi, animal activist and Union Welfare Minister, to ban import of animals for medical experiments has caused widespread resentment among biomedical researchers in the country.

Scientists are also upset over the new rules framed by the Committee for the Purpose of Control and Supervision of Experiments on Animals (CPSCEA) which is chaired by Ms Gandhi. They have warned that the rules, if implemented, would virtually halt most animal studies that are essential for development of drugs and vaccines.

Ms Gandhi was not available to comment on allegations that at the April 23 meeting she steamrolled the committee into accepting the regulations ignoring objections from scientists within and outside the committee. The next meeting broke up abruptly after Ms Gandhi told the dissenting scientists that they were free to walk out.

“We are very much concerned about the new rules and hope they will be modified,’’ said Ms Manju Sharma, Secretary of the Department of Biotechnology (DBT) which funds a number of research projects that require animal experiments.

To break the impasse, leading medical scientists from industry and the government, under a united banner, are now preparing to have a showdown with Ms Gandhi to present their concern in writing.

Their protest has the backing of scientific agencies like the Indian Council of Medical Research (ICMR) that have a lot to lose if the rules became law.

A note being circulated to scientists says the “failure to modify these rules carries the risk of the loss of a large and vital component of biomedical research in the country not through informed national debate and democratic choice but through passive delegation of decision making by default to a single non-representative group.’’

Under the new rules, no research institute can acquire animals without the committee’s permission and each experiment must be cleared by it before starting research work. And, animals can be bled and anaesthetised only by veterinary surgeons.

Rules also require funding agencies like the ICMR and the DBT to submit to the committee monthly reports of all animal experiments they are funding, the number of animals used, their age, sex, etc. And the kind of experiments done.

“This is ridiculous,” says Mr Sandip Basu, Director of the National Institute of Immunology in New Delhi. He says his own institute may be doing hundreds of experiments a year and the paper work for getting clearance for each will leave little time for actual research especially when the CPCSEA staff consists of one secretary, one technician and one peon.

The rules also demand drug companies to send their proposals in prescribed form to the committee before undertaking any experiments. Contract research organisations (CRO) are prohibited to carry out animal toxicological studies for foreign organisations.

Mr T.P. Suresh, general manager of Rallis India Limited, a Bangalore-based CRO and a member of the committee, says the rules will only “make way for ‘licence raj’ and prevent all animal experimentation through circuitous bureaucratic machinations.”

The rules also ban animal experiments for “teaching, training or retaining manual skill” and animal experiments cannot be repeated for confirming earlier results. But, scientists say that drug development needs repetitive experiments, they also refuse to comply with rules which require submission of completed reports to the committee as these reports may contain patentable information.

— PTI

Maize as anti-cancer agent

In a major breakthrough, scientists have developed a genetically engineered maize strain capable of secreting human antibodies against cancer.

According to a report published in the journal Scientific American, the ‘plantibodies’ secreted by the corn cells when purified and injected in a dose of 250 mg in cancer patients will stick to tumour cells and deliver the radio isotopes thereby killing the diseased cells. By transplanting a human gene in corn reproductive cells and adding other DNA that cranks up the cells production of foreign protein, US biotechnology firm Agracetus has created a strain that would yield about 1.5 kg of pharmaceutical quality antibodies per acre of corn, the report stated.

It quoted Agracetus scientist Vikram Paradkar saying that by this method “we could grow enough antibodies to supply the entire us market for our cancer drug—tens of thousands of patients— on just 30 acres’’.

Now this human antibodies produced in field crops are under going clinical trial. The technology can be a boon for the biotechnology firms which spent years and hundreds of millions of dollar on developing these antibodies. Until now genetists used cloned mouse cells or cultured human cell lines for antibody production. Cloned mouse cells sometimes produced drugs that either did not work or produced allergic reactions. While antibodies produced from human cell lines were specific and effective, they turn out to be quite costly as tens of thousands litres of such cloned cells produced only a kg or two kg of usable antibodies.

Though the development process in plants take a year longer than that in antibodies produced in cloned mouse cells or human cell cultures, but “start up costs are far lower, and in full scale production we can make proteins for orders of magnitude at a less costs,” Mr Paradkar said.

The report stated that the plantibodies reduces another risk also as the billions of cloned cells in fermentation tanks can catch human diseases, but plants don’t. Therefore, although the company must ensure that the plantibodies are free of pesticides and other contaminations, it can forgo expensive screening for viral and bacterial toxins. Since corn is not the only plant that mimic human cells, Agracetus is also cultivating soyabean that contains human antibodies against herpes simplex virus, a culprit in venereal diseases, in the hope of producing drug cheap enough to add to the contraceptives.

Another biotech firm ‘Planet Biotechnology’ is testing an anti-tooth decay mouthwash made with antibodies extracted from transgenic tobacco plants. Similarly, Crop Tech in Blacksburg has modified tobacco to manufacture an enzyme called glucocerebrosidase in its leaves. People with Saucher’s disease pay up to $ 160,000 per year for a supply of this protein which their cells could not make.

The report said though the transgenic plants can translate the subtle signals that control human protein processing, there are important differences as well.

Human cells adorn some antibodies with special carbohydrate molecules, but the plant cell sometimes stick wrong carbohydrates onto a human antibody.

If it happens, the maladjusted antibodies cannot stimulate the human body into producing its own immune response and they are rapidly filtered from the bloodstream, it said.

— PTI

Do not use cotton buds too often
IS it a good habit to clean your ears with a cotton tipped swab? No, say ear specialists. Cleaning your ears daily to keep them free of wax may do more harm than good. Firstly, ear wax is not dirt. It is an essential body product that protects the ear canal and ear drum from moisture, fungi and dust, reports ANF.
It is possible that in the process of cleaning you may push the ear wax further into the ear. With the passage of time, a block of wax can accumulate deep within the ear which may result in impaired hearing. If a drop of water gets trapped behind the wax the condition can cause much discomfort.
In a study of 650 persons it was found that people who cleaned their ears regularly with cotton-tipped buds were more like to suffer from wax-blocked ears than those who simply wiped their ears with a thin cloth after they took a bath.
In the case of children, doctors advise to clean only the easily visible parts without inserting anything in the ear. You may damage the ear-drum accidentally. If you suspect an ear block, visit your family physician who can wash it out with a jet of water. Do not go to a roadside ear-cleaner ever.

Discard high heeled shoes
IT is said that clothes and shoes make a person. This may or may not be true, but a high heeled shoe almost certainly will make a woman suffer from osteoarthritis with the passage of time in her 50s, reports ANF.
The findings of a study suggests that the present trend of changing from high heeled dress shoes to sneakers may provide women with far more than temporary comfort. It may help them to save their knees from the crippling pain that accompanies osteoarthritis in old age.
More women suffer from this ageing disease caused by wear and tear of bones than men. Medical researchers had long suspected that one cause behind this difference may be the practice of wearing high heeled shoes in younger years, Now their suspicion has come true.

Mono unsaturated fats better
RESEARCHERS have found that women who consume mono unsaturated fat, the main ingredient in olive and canola (rapeseed or sarson) oils, have a lower risk of breast cancer than those who eat other kinds of fats. Peanut and sunflower oil come next. Olive and canola oils have already been recommended as the safest sources of fat in a ‘heart healthy’ diet, says an ANF report.
But it does not mean that women should add these oils to their diet. Cooking oils, butter, hydrogenated fats and animal fats contain a mixture of saturated, poly-unsaturated and mono-unsaturated fat, followed by canola, peanut and sunflower oil. Butter, butter oil (ghee) and animal fats are rich in saturated fats.

Happily married men live longer
MEN who have a happy married life seem to live longer. This is the result of a study carried out in the UK after analysing death rates of nearly 1,000 men aged between 45 to 59.
Having a regular love life reduces the risk of death by about half. Love making seems to have a protective effect on men’s health. Men who engaged in lovemaking twice a week have a risk of dying half that of less active members who made love only once a month or even less, according to an ANF report.