Study Reaffirms Benefits of Aspirin
The old standby aspirin has again been shown to be as effective as new drugs in preventing heart attacks and death in patients who have already suffered one acute coronary event, such as chest pain or angina.
Aspirin blocks the clumping of blood platelets, a crucial step in the formation of clots that produce heart attacks. New medicines, such as a family of glycoprotein IIb/IIIa antagonists called fibans, are much more effective than aspirin at blocking platelet aggregation, and physicians had assumed that they would be more effective at preventing heart attacks.
An international team of researchers led by Dr. L. Kristin Newby of the Duke Clinical Research Institute in Durham, N.C., enrolled 9,233 patients who had suffered chest pain and had several other indicators of a coronary event such as high levels of heart enzymes. One-third were given daily aspirin, a third were given a low dose of the experimental drug sibrafiban, and the rest were given a higher dose of the drug.
The team reported in Saturday’s Lancet that sibrafiban showed no benefit beyond that of aspirin. Three months after the initial coronary event, 302 of those given aspirin had died or had another heart attack or severe recurrent angina, compared with 310 of those given low-dose sibrafiban and 303 of those given the high dose. But significantly more of those given the high dose of the drug suffered major bleeding as a result of the treatment.
Bacterium Can Produce Cancer Drug Faster
A Hayward, Calif., company has been able to induce a common bacterium to produce an anti-cancer drug that many researchers think will be the successor to the widely used Taxol.
Taxol is used to treat ovarian cancer, non-small-cell lung cancer and breast cancer, and annual sales of it and a related drug called Taxotere reached $1.6 billion in 1998. But Taxol and Taxotere have two major drawbacks: Many cancers are resistant to them, and they are insoluble in water. Because of that insolubility, the drugs must be used in combination with surfactants, which can cause severe hypersensitivity reactions.
Epothilone is a natural product that works by the same mechanism as Taxol but is water soluble, and tumors have not shown resistance to it. But the microorganism that normally produces it grows very slowly, and only small quantities of the drug have been available for clinical testing.
Researchers at Kosan Biosciences reported Friday in Science that they had isolated the complex of genes necessary for synthesis of epothilone and inserted them into a faster-growing species of bacteria, producing the drug. The discovery should make larger quantities available for further studies.
Gene Research May Help Heal Spinal Injuries
An international team of scientists has discovered the gene for a protein that prevents damaged nerve cells in the spine from reconnecting. Blocking the gene could eventually provide a dramatic new way to treat paralyzed victims of spinal injuries, but researchers cautioned that it could be many years before the discovery leads to clinical applications.
Scientists have long been puzzled by the observation that peripheral nerves are able to regrow while those in the central nervous system are not. Most assumed that there was a specific block for such regrowth, but isolating it proved difficult. Now, however, a team headed by Martin Schwab of the University of Zurich in Switzerland reported in Thursday’s Nature that it had isolated a gene, called Nogo, that controls the process.
Schwab told reporters that the researchers had partially severed the spinal cords of several rats, paralyzing the animals. Two weeks later, they gave the rodents antibodies that blocked the action of the Nogo protein. The nerves regrew, and the animals resumed normal activities.
Relenza Maker Warns of Possible Side Effect
The anti-influenza drug Relenza can cause side effects in patients with respiratory disorders, the drug’s manufacturer cautioned British physicians last week. Glaxo Wellcome said that the drug may cause bronchospasm, or restricted lung function, in patients with asthma or chronic obstructive pulmonary disease.
The company said that no deaths have been reported, and that the adverse effects “may or may not” be associated with Relenza. But the firm said at-risk patients should use a bronchodilator before using Relenza.
Protein Segment Kills Pneumococcal Bacteria
Researchers at St. Jude Children’s Research Hospital in Memphis, Tenn., have discovered a naturally occurring chemical that triggers the death of the killer bacterium Streptococcus pneumoniae.
Pneumococcal disease causes 40,000 deaths in the U.S. each year and is the leading killer of young children. It also causes ear infections, sepsis, bacteremia, pneumonia and meningitis. Some strains of the bacteria are becoming resistant to antibiotics, and the vaccine does not work in children younger than 2.
Dr. Elaine Tuomanen and her colleagues reported Friday in Molecular Cell that a naturally occurring peptide, a short segment of a protein, causes the bacteria to self-destruct. She speculated that the peptide itself or drugs that mimic its activity could be used for treating pneumococcal infections.
Team Studies Estrogen Therapy for Alzheimer’s
Seeming to contradict earlier reports, USC researchers found no benefit from estrogen therapy for women with Alzheimer’s disease. A few small studies had suggested that possibility, but they were generally too short and did not follow strict scientific guidelines, the team said.
A multi-university team headed by Dr. Victor H. Henderson enrolled 42 female Alzheimer’s patients. Half were given Premarin, and half a placebo. Forty of the women stayed in the study for four weeks, 36 for the full 16 weeks.
Henderson and his colleagues reported Tuesday in Neurology that they could find no significant differences in either mood or cognitive (thinking) ability between those taking estrogen and those taking the placebo. He said estrogen may yet be useful for treating Alzheimer’s, but it may be appropriate only for certain women or with longer treatment periods.
No Link Seen Between Ultrasound, Leukemia
Concerns about a link between prenatal ultrasound imaging and subsequent development of leukemia are unfounded, according to a new study by Swedish researchers. Dr. Estelle Naumberg and her associates at Uppsala University studied all children born in Sweden between 1973 and 1989 and diagnosed with leukemia, and compared the 652 subjects with carefully matched children who did not develop the disease.
They found that 200 of the children with leukemia had been exposed prenatally to ultrasound, compared with 214 of the healthy controls. The number of ultrasound exposures or the time during fetal development when the examination occurred did not affect the results.
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Medical writer Thomas H. Maugh II can be reached at [email protected].
