ABSTRACTS

NEW YORK, NY. People who have had an ischemic stroke are routinely prescribed 325 mg of aspirin to prevent a second stroke. Despite this intervention there is still an unacceptably high rate of recurrence. Researchers at 48 American academic medical centers have just reported the results of a clinical trial designed to determine if warfarin (Coumadin) would be more effective than aspirin. The trial involved 2206 stroke patients who had suffered an ischemic stroke within the previous 30 days. Patients whose stroke was due to surgery or atrial fibrillation were excluded from the trial. Half the participants were assigned to receive 325 mg aspirin daily for the two-year duration of the trial. The other 1103 patients received 2 mg warfarin daily with the dose being adjusted as required to maintain an international normalized ratio (INR) of 1.4 to 2.8.
At the end of the two-year period 196 (17.8%) of the patients in the warfarin group had either died or suffered a second stroke. In the aspirin group 176 (16.0%) of the patients had died or suffered a second stroke. The incidence of major hemorrhage was similar with a rate of 2.22 per 100 patient-years in the warfarin group and a rate of 1.49 per 100 patient-years in the aspirin group. Patients in the warfarin group had significantly more minor bleeding evens (20.8 per 100 patient-years) than did patients in the aspirin group (12.9 per 100 patient-years). The researchers conclude that warfarin is not superior to aspirin for prevention of a second stroke in the patient population studied.
Mohr, J.P., et al. A comparison of warfarin and aspirin for the prevention of recurrent ischemic stroke. New England Journal of Medicine, Vol. 345, November 15, 2001, pp. 1444-51
Powers, William J. Oral anticoagulant therapy for the prevention of stroke. New England Journal of Medicine, Vol. 345, November 15, 2001, pp. 1493-95 (editorial)

CARDIFF, UNITED KINGDOM. Researchers at the University of Wales report that older men with high blood viscosities have slower reaction times and poorer cognitive function than do men with less viscous blood. Their study involved 2154 men aged 55 to 69 years at the time of blood sampling and testing of cognitive function. The men were tested for reaction times and cognitive function using the AH4 test, which involves a series of alternating verbal and mathematical questions of increasing difficulty. Men with the lowest blood viscosity had the highest (best) scores. Fibrinogen level showed no association with cognitive function or reaction time. Hematocrit showed a U-shaped relationship with men with a hematocrit level of 0.46 having the best performance. Hematocrit (packed cell volume) is the volume of red blood cells in blood, expressed as a fraction of the total volume of the blood.
The researchers point out that hematocrit can be lowered by venesection (blood letting) and that several studies have shown that people with mental confusion or reduced alertness can benefit substantially from having their hematocrit lowered by venesection. Dr. Gordon Lowe of the Royal Infirmary in Glasgow points out, in an accompanying editorial, that drinking plenty of water can also lower blood viscosity and hematocrit.
Elwood, Peter C., et al. Cognitive function and blood rheology: results from the Caerphilly cohort of older men. Age and Ageing, Vol. 30, March 2001, pp. 135-39
Lowe, Gordon D.O. Is sticky blood a treatable determinant of cognitive decline and of dementia? Age and Ageing, Vol. 30, March 2001, pp. 101-03 (editorial)

BOSTON, MASSACHUSETTS. The US National Academy of Sciences has released new recommendations for the daily intakes of vitamins and minerals. One major change concerns vitamin A. It was previously thought that darkly colored fruits and vegetables could provide adequate amounts of vitamin A through conversion of carotenoids. This has now been found to be untrue. Carotenoids are only converted to vitamin A at half the rate previously thought, so vegetarians in particular may need to increase their intake of vitamin A from other sources. The new recommendations also, for the first time, list tolerable upper intake levels (ULs) for many vitamins and minerals.
Recommended daily intakes (ULs in brackets) for adults in good health are as follows:

• Vitamin A – 900 micrograms (4500 IU) for men and 700 micrograms for women (UL: 3000 micrograms)
• Vitamin C – 90 mg (UL: 2000 mg)
• Vitamin E – 15 mg (UL: 1000 mg)
• Vitamin K – 120 micrograms for men and 90 micrograms for women
• Choline – 550 mg for men and 425 mg for women (UL: 3500 mg)
• Calcium - 1000-1300 mg (UL: 2500 mg)
• Magnesium – 320-420 mg
• Manganese – 1.8-2.3 mg (UL: 11 mg)
• Molybdenum – 45-50 micrograms (UL: 2000 micrograms)
• Selenium – 55-60 micrograms (UL: 400 micrograms)
• Zinc – 8-11 mg (UL: 40 mg)

The report specifically points out that the recommendations are designed "to meet the needs of individuals in the United States and Canada who are healthy and free from specific disease or conditions that may alter their daily nutritional requirements."
Russell, Robert M. New micronutrient dietary reference intakes from the National Academy of Sciences. Nutrition Today, Vol. 36, May/June 2001, pp. 163-71

ROME, ITALY. Italian researchers have found that girls who spend time in the kitchen while their mother is cooking on a gas stove tend to have impaired lung function. The study involved 702 boys and girls aged 11 to 13 years. The participants were categorized according to how often they were in the kitchen while the gas stove was in use (never, sometimes, often). They all underwent spirometric testing to measure lung function and skin prick testing to determine atopic (allergic) reactions. Blood samples were also analyzed to determine serum level of IgE (immunoglobulin E) another marker for allergy.
The researchers conclude that lung function (forced expiratory volume at 75 per cent of vital capacity) in boys is not affected by time spent in the kitchen. The reduction in lung function for girls who were present often or sometimes during stove usage was an average 11.1 per cent and 10.3 per cent respectively and was statistically significant. The reduction was limited to girls with a high level of IgE. The researchers also noticed that more boys than girls had asthma (10.6 per cent versus 3.7 per cent) and a positive skin prick test (29.7 per cent versus 22.8 per cent). They warn that exposure to gas cooking is harmful to girls with a high level of serum IgE and suggest that kitchens should be inspected and appropriate ventilation installed if needed.
Corbo, G.M., et al. Effect of gas cooking on lung function in adolescents: modifying role of sex and immunoglobulin E. Thorax, Vol. 56, July 2001, pp. 536-40

FARMINGTON, CONNECTICUT. Rheumatoid arthritis, scleroderma, and systemic lupus erythematosus are among more than 60 so-called autoimmune disorders. The characteristic feature of these diseases is that the immune system attacks normal body tissues as if they were foreign invaders. It is generally accepted that an autoimmune disease occurs when a genetically susceptible host is exposed to an appropriate environmental trigger – in many cases an infection.
Researchers at the University of Connecticut have recently completed a study of death certificates for 860,648 Americans listed as having a professional occupation. They conclude that school teachers, notably secondary teachers, have a significantly higher mortality from autoimmune diseases than do people of other professions. Overall teachers had a 2.3 per cent mortality rate from autoimmune diseases as compared to 1.7 per cent for other professions. The excess mortality was exceptionally high for teachers between the ages of 35 and 44 years. In this age group teachers had a 49 per cent higher mortality from autoimmune diseases than did other professionals. The excess mortality (143 per cent) was even higher for secondary teachers. Secondary teachers were particularly likely to die from multiple sclerosis (205 per cent increased mortality) and systemic lupus erythematosus (182 per cent increased mortality).
The researchers speculate that the reason for the increased mortality is that teachers have significantly higher exposures to infectious agents such as the Epstein-Barr virus (mononucleosis) and rhinoviruses early in their career than do other professions.
Walsh, Stephen J. and DeChello, Laurie M. Excess autoimmune disease mortality among school teachers. Journal of Rheumatology, Vol. 28, July 2001, pp. 1537-45

BORDEAUX, FRANCE. DHEAS (dehydroepiandrosterone sulfate) is a steroid hormone secreted by the adrenal gland and is the precursor of androgens (male sex hormones) and estrogens. Several studies have shown that DHEA and DHEAS levels decline with age and this has lead to speculation that there might be a connection between DHEA levels and longevity.
Researchers at the University of Bordeaux have just released the results of a study aimed at clarifying this point. The study involved 595 volunteers (253 men and 342 women) over the age of 65 years when first enrolled in 1988. A year after enrollment the volunteers had blood samples drawn for analysis of DHEAS levels. This analysis was repeated for 290 subjects (119 men and 171 women) after an additional seven years.
The researchers conclude that DHEA levels tend to decline by an average of 2.3 per cent per year for men and 3.9 per cent for women. However, they noted an increase in about 30 per cent of the subjects. They found no correlation between DHEAS levels and functional, psychological or mental status or between DHEAS levels and mortality in women. However, in men low DHEAS levels were associated with a 1.9 times higher risk of death. This association was particularly pronounced in men under 70 years of age (a 6.5 times greater mortality) and in male smokers (a 6.7 times greater mortality). The researchers conclude that DHEA supplementation may be beneficial for both current and former male smokers.
Dr. Samuel Yen of the University of California concurs with this recommendation and points out that DHEA should be taken before bedtime to simulate the circadian rise of DHEA secretion at night. He also points out that several other studies have found DHEA supplementation to be beneficial in women with low levels and in patients with systemic lupus erythematosus.
Mazat, Lise, et al. Prospective measurements of dehydroepiandrosterone sulfate in a cohort of elderly subjects: relationship to gender, subjective health, smoking habits, and 10-year mortality. Proceedings of the National Academy of Sciences, Vol. 98, No. 14, July 3, 2001, pp. 8145-50
Yen, Samuel S.C. Dehydroepiandrosterone sulfate and longevity: new clues for an old friend. Proceedings of the National Academy of Sciences, Vol. 98, No. 15, July 17, 2001, pp. 8167-69 (commentary)

STOCKHOLM, SWEDEN. Some studies have found a correlation between low vitamin B12 levels and the development of Alzheimer's disease (AD) and dementia; other studies have found no such correlation. Researchers at the Karolinska Institute now provide convincing evidence that a deficiency of either vitamin B12 or folic acid (folate) is associated with an increased risk of AD and dementia.
Their study involved 370 non-demented people aged 75 years and older who were not supplementing with vitamin B12 or folate. The participants were tested at baseline to determine mental status and had blood samples drawn for analysis of vitamin B12 and folate levels. Only subjects who showed no signs of dementia were included in the follow-up group. Three years later 77 of the participants had developed dementia; of these 59 were diagnosed with AD. Compared with participants with normal levels of vitamin B12 and folate the participants with low levels of at least one of the vitamins had a 2.3 times higher risk of AD and a 1.7 times risk of any kind of dementia. These risk estimates were obtained after adjusting for other risk factors such as age, sex, and educational attainment.
The researchers speculate that homocysteine, a known neurotoxin, may be involved in the development of AD and that vitamin B12 and folic acid help prevent this effect by reducing homocysteine levels in the body.
Wang, H-X, et al. Vitamin B12 and folate in relation to the development of Alzheimer's disease. Neurology, Vol. 56, No. 9, May 8, 2001, pp. 1188-94

HELSINKI, FINLAND. There is considerable evidence that the risk of colorectal cancer (cancer of the colon or rectum) is intimately linked to diet. For example, it is clear that a high consumption of cured meats and salted and smoked fish is a potent risk factor. Some studies have found that a high intake of red meat, animal fat, and total fat also increases the risk, but other studies have found no such connection.
A team of Finnish and Swedish researchers now reports that a high intake of cholesterol is a potent risk factor. Their study involved almost 10,000 Finnish men and women who were enrolled in 1967. By late 1999 54 of the men and 55 of the women had developed cancer of the colon (63 cases) or the rectum (46 cases). The researchers found that men who consumed more than 668 mg/day of cholesterol had a 3.26 times greater risk of colorectal cancer than did men who only consumed 402 mg/day or less. The corresponding values for women were more than 501 mg/day as compared to less than 288 mg/day for a risk increase of 3.26 times. Note: One medium-sized egg contains about 300 mg of cholesterol. The risk estimate was after correcting for age, sex, body mass index, occupation, smoking, geographic region, energy intake, and consumption of vegetables, fruits and cereals. The researchers found no statistically significant association between colon cancer risk and the intake of total fat and intake of saturated, monounsaturated, and polyunsaturated fatty acids. There was a trend for the risk to increase with higher intakes of eggs (especially fried eggs) and red meat, but this trend did not reach statistical significance.
The researchers make the interesting observation that it may not be so much a high cholesterol intake that increases the risk, but rather a low ratio between the intake of plant sterols (from vegetable fats) and cholesterol. Apparently most study participants had especially low intakes of vegetable fats.
Jarvinen, R., et al. Dietary fat, cholesterol and colorectal cancer in a prospective study. British Journal of Cancer, Vol. 85, No. 3, August 3, 2001, pp. 357-61

CALGARY, CANADA. Canadian researchers have released the results of a major study evaluating the effect of lifetime physical activity on breast cancer risk. The study included 1233 women with breast cancer and 1237 controls and was conducted in Alberta during the period 1995-97. All study participants underwent comprehensive interviews to determine their lifetime physical activity level, diet, smoking status, alcohol consumption, reproductive history, and body measurements. The researchers found no correlation between lifetime physical activity level and breast cancer risk in premenopausal women. Among postmenopausal women, however, they observed a clear risk reduction with increased household and occupational physical activity, but not with increased recreational physical activity. Women who had been most active during their lifetime (household and occupational) had an almost 40 per cent lower risk of breast cancer than did less active women. Active women who did not consume alcohol had a 61 per cent lower risk and active women who had not had any children (nulliparous) had a 78 per cent risk reduction. The researchers conclude that a high level of physical activity over a lifetime reduces the risk of breast cancer in postmenopausal women.
Friedenreich, C.M., et al. Case-control study of lifetime physical activity and breast cancer risk. American Journal of Epidemiology, Vol. 154, August 15, 2001, pp. 336-47

MEXICO DF, MEXICO. Fibromyalgia is a painful rheumatic condition that affects about 2 per cent of the population and is particularly prevalent among women. It is often accompanied by chronic fatigue syndrome and such symptoms as fatigue, anxiety, headaches, sleep disturbances and morning stiffness. Fibromyalgia has long been passed off as a "hysterical complaint" primarily because its origin is unknown, it is mainly a women's disease, and there is no effective treatment for it.
Mexican researchers have now produced what is perhaps the first evidence that fibromyalgia actually is a "real" disease and that it is intimately linked to a dysfunction of the autonomic nervous system. Their study involved 19 women (aged 26 to 60 years) and 19 healthy controls. Ten of the 19 fibromyalgia patients also had chronic fatigue syndrome. All study participants had their heart rate variability (HRV) measured while lying down (supine position) and immediately upon reverting to a standing position. HRV is a measure of the balance between the sympathetic (adrenergic) and parasympathetic (vagal) branches of the autonomic nervous system. The researchers noted a profound difference in the response to the change from supine to standing position. In the normal subjects it was accompanied by a 40 per cent increase in sympathetic activity while the fibromyalgia patients experienced a 24 per cent decrease in sympathetic activity. The researchers conclude that this difference is highly significant and may explain many of the symptoms of fibromyalgia particularly increased fatigue and a lowered pain threshold.
Hungarian researchers report similar findings in a study of 34 fibromyalgia patients.
Martinez-Lavin, Manuel, et al. Orthostatic sympathetic derangement in subjects with fibromyalgia. Journal of Rheumatology, Vol. 24, No. 4, 1997, pp. 714-18
Kelemen, Judit, et al. Orthostatic sympathetic derangement of baroreflex in patients with fibromyalgia. Journal of Rheumatology, Vol. 25, No. 4, 1998, pp. 823-25 (letters to the editor)

BERN, SWITZERLAND. There is substantial evidence that high levels of homocysteine (a sulphur- containing amino acid) are directly associated with an increased risk of cardiovascular disease. It is believed that homocysteine causes damage to the lining of the arteries and thereby promotes atherosclerosis and hypertension. The normal range of homocysteine in adults is between 5 and 15 micromol/L. An excess of just 5 micromol/L has been found to correspond to an increased risk of coronary artery disease of 60 per cent in men and 80 per cent in women.
A team of American and Swiss researchers now reports that the severity of cardiovascular disease, as indicated by the number of arteries affected, is directly proportional to the homocysteine level. The study involved 631 patients who had been referred for coronary angiography. The patients had their homocysteine levels measured and an angiogram taken. The researchers found that homocysteine levels increased in a linear fashion from 9.2 micromol/L for patients with no coronary disease to an average of 12.4 in patients with three-vessel disease. The researchers also noted that men were far more likely to have blocked arteries than women. Age, smoking, hypertension, and high cholesterol levels were other significant risk factors for coronary artery disease found in the study. The researchers recommend routine testing of homocysteine levels as an important factor in evaluation risk for coronary artery disease.
Schnyder, Guido, et al. Association of plasma homocysteine with the number of major coronary arteries severely narrowed. American Journal of Cardiology, Vol. 88, November 1, 2001, pp. 1027-30

COLLEGE PARK, MARYLAND. About 1.4 million cases of salmonella food poisoning occur each year in the United States. Most cases resolve on their own within five to seven days, but between 3 to 10 per cent require treatment with antibiotics. Researchers at the University of Maryland have concluded that most of the cases are caused by salmonella contamination of meat. They analyzed 200 samples of ground meat (chicken, beef, turkey and pork) and found that 20 per cent of them contained salmonella bacteria. Of even greater concern was the finding that 84 per cent of the isolated salmonella strains were resistant to at least one antibiotic while 53 per cent were resistant to at least three antibiotics. The development of antibiotic- resistant strains is of serious concern as it makes it a lot more difficult to treat an infection in both humans and animals. The researchers believe that the growth of resistant salmonella strains is due to the vast overuse of antibiotics in the meat industry. It is estimated that over 26 million lbs. (11.2 million kgs.) of antibiotics are given to animals every year. Only 10 per cent of this amount is for treatment of infections. The remaining 90 per cent is for promotion of growth. In contrast, it is estimated that only three million lbs. of antibiotics are given to humans every year. Dr. Sherwood Gorbach of Tufts University recommends that the use of antibiotics for growth promotion in animals be banned and the use of fluoroquinolones and third- generation cephalosporins be reserved for humans.

White, David G., et al. The isolation of antibiotic-resistant salmonella from retail ground meats. New England Journal of Medicine, Vol. 345, October 18, 2001, pp. 1147-54
Gorbach, Sherwood L. Antimicrobial use in animal feed – time to stop. New England Journal of Medicine, Vol. 345, October 18, 2001, pp. 1202-03 (editorial)

NEWSBRIEFS

An explanation for homeopathy?
A team of researchers in South Korea may have come up with an explanation for one of the more astounding properties of homeopathic remedies – the more dilute they are the stronger their effect. The researchers found that molecules dissolved in water tend to cluster together in larger and larger aggregates the more water is added to the solution. Dr. Fred Pearce of University College London speculates that the larger clusters and aggregates might interact more easily with biological tissue and thus explain why highly dilute homeopathic solutions have a stronger effect than less dilute ones.
New Scientist, November 10, 2001, pp. 4-5

Keep your fingernails clean
Research scientists at King's College London have found that cows with mad cow disease (BSE) and people with multiple sclerosis (MS) both have abnormally high levels of antibodies to the common soil bacteria, Acinetobacter. They speculate that exposure to this bacterium, which is often found under people's fingernails, may initiate both MS and BSE. Their hypothesis, however, is not universally accepted by other scientists working in the field.
New Scientist, November 17, 2001, p. 17

Deep-sea bacteria in sunscreens
French researchers report that proteins obtained in a fermentation process based on the bacterium Thermus thermophilus may be highly effective in preventing free radical damage to the skin during sun exposure. T. thermophilus is found near hot hydrothermal vents as much as 2 km down on the bottom of the Pacific Ocean. It thrives at 75 degrees C and preliminary experiments have shown that it is particularly effective in preventing lipoperoxidation and ultraviolet damage to skin cells.
New Scientist, November 3, 2001, p. 23

New breast cancer screening tool
Researchers at Guy's Hospital in London have developed a camera so small that it can be inserted into one of the 15 or so holes in a woman's nipple. Once inside the milk duct it can scan for lumps or dull surfaces that may be indicative of a developing cancer.
New Scientist, October 27, 2001, p. 29

DHEA may not benefit healthy older men
There is substantial evidence that men with adrenal insufficiency can benefit from supplementation with dehydroepiandrosterone (DHEA). What is less clear is whether healthy older men can benefit from DHEA. German researchers now report that supplementing with 50 mg/day of DHEA for four months had no effect on sex drive, exercise capacity, cholesterol levels or bone mass in a group of 22 healthy men between the ages of 50 to 69 years. The supplementation did increase DHEA levels to those generally found in young men, but apparently with no obvious benefits.
Journal of Clinical Endocrinology & Metabolism, Vol. 86, October 2001, pp. 4686-92

Elderly women should go easy on coffee
American researchers report that postmenopausal women with a high caffeine intake tend to lose bone mass much more extensively than do women with a lower consumption. Their study involved 489 women between the ages of 65 and 77 years. Women with an intake of more than 300 mg/day of caffeine (18 oz of brewed coffee) were found to have a significantly greater loss of bone mass at the spine than did women who consumed less than 300 mg/day. A subgroup of the women was found to have a genetic abnormality that further increased their caffeine-induced bone loss. Other research has shown that caffeine-induced bone loss can be partially offset by an adequate calcium intake.
American Journal of Clinical Nutrition, Vol. 74, November 2001, pp. 694-700, 569-70

Calcium for healthy teeth
Researchers at Boston University School of Dental Medicine report that supplementing with calcium and vitamin D is effective in preventing loss of teeth in older people. Their experiment involved 145 healthy subjects aged 65 years or older. Half the group was randomized to receive 500 mg/day of calcium citrate/maleate and 700 IU/day of vitamin D3 while the other half received placebos. After three years 13 per cent of the people in the supplement group had lost one or more teeth as compared to 27 per cent of the placebo group members having lost one or more teeth.
American Journal of Medicine, Vol. 111, October 15, 2001, pp. 452-56