January 1998

Does Olestra Cause Digestive Problems?
January 14, 1998

Are digestive problems the price you must pay for lower fat and calories? A new Johns Hopkins study says no.

The study examined olestra, a fat substitute approved last year for use in snack foods like potato, corn and tortilla chips. In some studies, people reported abdominal cramps and other unpleasant effects after eating products made with olestra. But those trials asked people to consume the stuff at every meal for nearly two full months. Johns Hopkins director of digestive diseases Dr. Lawrence Cheskin wanted to test olestra in the real world. So he asked 1,100 movie-goers to munch a bag of potato chips while they watched a favorite flick. Half of the bags had olestra and the others had ordinary fat.

"In this type of setting, which is a typical setting for eating potato chips at a single sitting--as much or as little as you want to eat--there does not seem to be any excess GI effects from olestra compared to regular potato chips," explains Cheskin.

Sixteen percent of those who ate the olestra-laden chips did report some gastro-intestinal discomfort later. But the number was even higher for those who crunched the regular kind, leaving researchers to conclude that in normal helpings, olestra doesn't cause any problems.


Human Cell Lifespan Extended
January 14, 1998

For the first time, researchers have confirmed that the "clock" thought to control aging in human cells does indeed dictate that process. What's more, they have found a way to circumvent the process - extending the lifespan of normal, healthy human cells, according to a report in Science.

The finding has "profound" implications for the study of cancer, which may use the same process to escape the aging process, according to an editorial accompanying the study.

And it may lead to treatment for human disease caused by worn out cells, such as macular degeneration - the leading cause of blindness in those over 65.

"This research raises the possibility that we could take a patient's own cells, rejuvenate them, then modify the cells as needed and give them back to the patient to treat a variety of genetic and other diseases," said senior investigator Dr. Woodring E. Wright in a statement released by the University of Texas Southwestern Medical Center at Dallas. "The potential long-term applications are simply staggering," said Wright, a professor of cell biology and neuroscience. The study was a collaborative effort involving researchers at the medical center and at Geron Corp., in Menlo Park, California.

Most cells will divide roughly 50 times in the laboratory before entering a resting state known as senescence, a process that also occurs in the body. For more than a decade, researchers have suspected that telomeres, sections of DNA at the tips of chromosomes, control that process.

Like minutes ticking on a clock, a piece of telomere is lost each time the cell divides. But some cells contain an enzyme, called telomerase, that can re-build the telomere after cell division.

In the new study, the gene for telomerase was inserted inside three types of cells that don't normally carry the enzyme - retinal pigment epithelial cells, foreskin fibroblasts, and the vascular endothelial cells - or those lining blood vessels. In contrast with cultured cells that have telomere shortening, the genetically engineered cells continued to vigorously divide and have long telomeres.

The treated cell population doubled at least 20 more times than normal and continues to grow, according to the report. The new findings confirm that telomeres are the "clock" that keeps cells from growing out of control, according to an editorial by Titia de Lange, of the Laboratory for Cell Biology and Genetics at The Rockefeller University in New York. And that mechanism has all "the makings of a powerful tumor suppressor system," de Lange wrote.

"The results should strengthen the determination of those who are searching for telomerase inhibitors as potential anti-cancer agents."

SOURCE: Science (1998;279:349-352, 334-335)


Type A Sydney Flu Virus Hits US
January 14, 1998

A flu strain found in Australia last year has found its way to the US - and health experts are not certain how much protection this year's flu vaccine offers against it.

The Type A Sydney flu strain (A/Sydney) has been found in 40% of cases tested by the US Centers for Disease Control and Prevention (CDC) in Atlanta since October. This particular flu strain was not included in the vaccine designed to cover the 1997-1998 flu season.

But the current flu vaccine does offer protection against a close relative of A/Sydney, the Type A Wuhan (or Nanchang) influenza virus - and so may also offer "partial" protection against the Sydney strain, according to a CDC expert. Both of the viruses are Type A H3N2 viruses. So far this season, the Wuhan strain has been found in 60% of flu samples analyzed at the CDC.

"Years when the A-H3 viruses are the predominant circulating type... are when disease tends to be more severe in high-risk groups in terms of hospitalization and fatalities," said Dr. Stephen Ostroff, associate director of the National Center for Infectious Diseases at the CDC in an interview with Reuters.

However, it is still relatively early in this year's flu season, too early to tell if the A/Sydney strain will make an impact on flu deaths this year, added Ostroff.

Ostroff encourages people - especially those in high-risk groups such as those over 65 and those with chronic lung diseases - to be vaccinated against the flu.

"At least, (this year's flu vaccine) offers partial protection against A/Sydney. At best, it's protection could be quite good," he explained.

The Sydney flu virus was identified in Australia last June. According to a report in Tuesday's USA Today, this strain of flu is believed to have arrived in the US in September when an Australian tourist took a New England cruise, and appears to have infected other people on board the ship.

Cases of A/Sydney influenza have been reported in California and New York.


Reduced Brain Blood Flow During Heavy Snoring
January 9, 1998

The underlying mechanism of increased stroke risk associated with heavy snoring most likely involves an episodic reduction in blood flow in the middle cerebral artery (MCA) during the non-rapid eye movement (NREM) stage of sleep. That's according to a team of US and German researchers, reporting in the January issue of Stroke.

Lead investigator, Dr. Nikolaus Netzer of Case Western Reserve University in Cleveland, Ohio, and colleagues evaluated 11 men and 1 woman with a median age of 54 years who were self- reported "heavy snorers." The subjects were selected because of their likelihood of having sleep- disordered breathing.

The researchers monitored the subjects using continuous Doppler sonography during sleep for changes in cerebral blood flow resulting from an episode of apnea (where breathing stops for a short period during sleep) or hypopnea (where breathing becomes more shallow and/or slower). They observed significant declines in blood flow during 76% of the obstructive hypopnea episodes and during 80% of the obstructive apneas. However, significant declines were apparent in only 14% of the episodes of central apnea.

"While duration of events was not significantly different, MCA blood flow reductions were associated only with the duration of the obstructive hypopneas... and not with the duration of central... or obstructive... apneas." Similarly, reductions in arterial oxygen saturation corresponded to reduced blood flow during obstructive hypopnea episodes only.

"Our hypothesis is that the negative thoracic (internal chest)... pressure causes a reduction in blood flow in the middle cerebral artery that may lead to stroke," Netzer commented in an American Heart Association press release.

Based on these findings, Netzer's team suggests "...that obstructive hypopneas, the physiological correlate for heavy snoring, have at least as great or an even greater significance than either central or obstructive apneas." The next step of the research will be to determine the relative risk for stroke by specific type of breathing-related sleep disorder.

SOURCE: Stroke (1998;29:87-93)


Potassium Lowers Blood Pressure
January 16, 1998

Potassium, either in foods or in supplements, can lower blood pressure in people with low daily intake of the mineral, according to a study in the current issue of the journal Hypertension.

Lead author Dr. Frank Sacks, of the Harvard School of Public Health in Boston, believes that individuals concerned about their blood pressure "should eat a diet high in potassium or take supplements." Potassium-rich foods include fruits such as bananas and oranges, as well as leafy green vegetables.

The researchers studied the effects of various mineral supplements on the blood pressure of 300 middle-aged women with normal, healthy blood pressures. Each of the women (who were part of the larger, ongoing Nurses' Health Study) also had low levels of daily potassium intake relative to the general population.

The women were placed on a four-month regimen of daily supplements of either potassium (1600 milligrams/day), calcium (1200 mg/day), magnesium (336 mg/day), a combination of all three supplements, or placebo.

The researchers discovered that, "compared with the placebo group, blood pressure decreased significantly... in the potassium group by 2.0 mm Hg for systolic pressure (the first number in a blood pressure reading)... and by 1.7 mm Hg for diastolic pressure (the second number)."

However, they found "no significant (blood pressure) changes in the magnesium or calcium groups."

And the researchers found that supplement regimens made up of combinations of the three minerals had much less of an impact on blood pressure than supplementation with potassium alone. The authors say this suggests that "magnesium and calcium, ineffective as single supplements, could actually interfere with the blood pressure-lowering action of potassium."

They also believe that potassium supplementation may not significantly lower blood pressure in those individuals who already have an average or high daily dietary intake of the mineral.

Sacks said that although the study focused on women with normal blood pressure "...previous studies have shown that potassium in people with high blood pressure has a greater effect of lowering blood pressure by 4 to 5 mm Hg."

SOURCE: Hypertension (1998;31:131-138)


The 30-Minute Workout
January 14, 1998

Wondering how to fit exercise into your day? What about a 30-minute workout at lunch?

Spend the first 20 minutes either on the Lifecycle or the treadmill (at a three to five percent incline, walking three to four miles per hour) is a good idea.

Finish off your workout using the weight equipment, including upper body exercises -- especially triceps (back of arms), shoulders, chest, and back.

For your lower body, concentrate on the quads (front of thighs), hamstrings (back of thighs), along with gluteal (butt) and inner thigh exercises. Spend a few minutes doing abdominal exercises.

You may not be able to fit all of this into your 30-minute routine, but be organized and vary the exercises so you hit each area at least once a week.

Good luck and don't give up too soon. It's hard to say how long it will take to see your results, but you are on the right track and you just need to hang in there.


 Dextromethorphan Linked To Birth Defects
January 16, 1998

Dextromethorphan, an ingredient in some cough medicines, has been shown to cause birth defects and fetal death in chicken embryos exposed to concentrations relative to those typically taken by humans, according to a paper in the January issue of Pediatric Research.

Dr. Thomas H. Rosenquist and colleagues at the University of Nebraska gave chicken embryos various doses (5, 50 or 500 nanomoles/deciliter) of dextromethorphan over three consecutive days. More than half of those given the highest dose died, while about one-eighth of the survivors developed congenital defects including "...neural tube defects such as spina bifida, facial defects similar to cleft palate, as well as cranial defects," a University press release explains.

"Dextromethorphan was also highly lethal at 50 nmol/embryo/d," the team writes in the Pediatric Research paper.

According to Rosenquist, these findings add weight to recently reported findings from the Baltimore-Washington Infant Study in which a history of cough medicine use emerged as a risk factor for congenital malformations.

"We found that dextromethorphan causes defects so early in the development of the embryo that in many cases the woman wouldn't even know she is pregnant," Rosenquist said in the statement. "We feel that a single dose is capable of causing a birth defect and that, ultimately, it could be the cause for a woman to have a miscarriage."

Dextromethorphan suppresses cough by acting on receptors in the adult central nervous system. But in embryos, the drug appears to "knock out" the receptors, thus leading to the defects.

Further study is needed, but in the meantime, Rosenquist suggests that pregnant women be advised not to use dextromethorphan-containing cough medicine.

"Although we used chicken embryos in our study, modern molecular biology shows that the same genes regulate early development in virtually all species - from insects to worms to humans," said Rosenquist. "Based on this, it can be predicted that the effects dextromethorphan had on the chicken embryos also would occur in human babies."

SOURCE: Pediatric Research (1998;43:1-7)


WHO Warns Against Diet Supplements To Prevent Cancer
January 13, 1998

The World Health Organization (WHO) cautioned against using dietary supplements to prevent cancer, saying that eating fresh fruits and vegetables remained the preferred defense against the disease.

In a statement released here, the WHO warned in particular against the promotion of carotenoid pills as a preventive treatment.

"Fresh fruits and vegetables ... remain the first line of defense against the disease," the statement said.

Published data from several clinical trials involving carotenoids and beta-carotene showed that "in none of these trials did the drug have a significant preventive effect," the statement said.

"Moreover, when given to regularly smoking volunteers, it was shown to increase the risk of lung cancer and mortality from cardiovascular diseases," it quoted Dr. Harri Vainio as saying.

Vainio heads the chemoprevention unit at the WHO's International Agency for Research on Cancer (IARC) in Lyon, France, where a working group of 23 scientists from 10 countries held a conference in December 1997.

"Our group came to the conclusion that ... none of these substances should be promoted to the general population as a tumor-preventive treatment," Vainio said.

"It appears at present that cancer prevention by fresh fruits and vegetables remains more effective than taking one or several of their constituents as dietary supplements."


Doctors Call Tobacco Deadlier Than Air Pollution
January 26, 1998

Smoking is vastly more damaging to peoples' lungs than air pollution, medical specialists said, criticizing the media for focusing too much on the latter.

"Some 60,000 people each year in France die 15 years too early as a result of smoking," Bertrand Dautzenberg, a lung specialist at a Paris hospital, said at a conference in this southern French city.

"A person who smokes a packet of cigarettes a day has one chance in two of dying from an illness related to tobacco," he said.

"Air pollution every year aggravates the cases of 500 to 1,000 people who are already stricken with serious lung diseases and condemned in the short term," he said.

"When these very sick patients are regularly submitted to air pollution, life expectancy is diminished by four weeks," he said.

Jean-Claude Puget of the Center for Treatment of Respiratory Illnesses in Paris said: "Today people are certain pollution kills but it's just media manipulation because the dangers of pollution are infinitely less than those of tobacco."

Jean-Paul Janssens, the head doctor at the Respiratory Rehabilitation Center in Rolle, Switzerland, said there was a worrisome resurgence in smokers among adolescents and young women between 15 to 20 years old.

Some 300,000 adolescents between 14 and 16 years old join the ranks of smokers in France each year, he said.

Young people were easily influenced by cigarette advertising.

"Our role can only be to inform and channel the media assault because we will never have the means to counter those of the tobacco industry," Janssens added.

Dautzenberg said "smoking also means 48 billion francs (eight billion dollars) enter (French) state coffers every year. We must therefore fight the finance ministry to launch anti- tobacco campaigns."


Sexes React Differently To Forced Sex
January 26, 1998

Under extreme psychological stress, adolescent girls typically turn to "internalizing" behaviors such as bulimia or withdrawal, while boys tend to "act out" in violent, aggressive behaviors. But a new study finds that teenagers who are forced or pressured to engage in sexual intercourse deviate from this pattern, with girls turning to violence and boys internalizing their psychological distress.

"Behaviors differed among sexually active male and female adolescents reporting being forced or pressured to have sex," according to research appearing in the current issue of the journal Archives of Pediatrics and Adolescent Medicine.

In 1995, researchers led by Dr. Lydia Shrier of Harvard Medical School in Boston, Massachusetts, sent detailed psychological and behavioral questionnaires to nearly 22,000 8th- through 12th-grade students. On the basis of those questionnaires, the researchers created a subset of 7,884 students whose answers identified them as sexually active. These students' answers formed the basis of the study.

A respondent's involvement in an incident of either coerced of forced sex was determined by his or her reply to the question "Have you ever been forced or pressured to have sexual intercourse?"

The researchers discovered that "of the sexually active students, 30.3% of the girls and 9.9% of the boys reported ever being forced or pressured to have sexual intercourse.

Risks for certain potentially dangerous behaviors, such as suicidal tendencies, unprotected sexual activity, or involvement in an unwanted pregnancy were similar for those students of either gender who had acknowledged a previous history of forced intercourse.

However, contrary to their original expectations, the researchers discovered that "girls who had been in at least one physical fight in the past year were 1.65 times (65%) more likely than other sexually active girls to report a history of having forced or pressured sex."

They also found that boys who admitted to having recently engaged in bulimic activity were more than three times (3.44) as likely to have been forced or pressured into unwanted sex than boys whose sexual activity was exclusively consensual. In contrast, the researchers note that a history of forced sex seems to play no role in triggering bulimia among adolescent girls.

Based on their findings, the study authors believe that any psychiatric therapy focused on children demonstrating these behaviors should include an investigation of a possible history of unwanted intercourse.

SOURCE: Archives of Pediatrics and Adolescent Medicine (1998;152:57-63)


Tick Bite Treatment Often Unnecessary
January 21, 1998

Physicians are ordering unnecessary and costly blood tests and prescribing ineffective antibiotics for tick bites, perhaps in response to patients' insistence on treatment for Lyme disease, a new study suggests.

The Centers for Disease Control and Prevention and other medical sources do not recommend blood tests or antibiotic treatment just after a tick bite, because Lyme disease is not detectable until several weeks after infection. Yet, a study in Eastern Maryland, where tick bites are prevalent, revealed that "(m)ost patients with tick bites are undergoing costly serologic (blood) testing of no benefit, and the majority are receiving prophylactic antibiotic therapy, an intervention of unproven benefit," according to Dr. Alan D. Fix from the University of Maryland School of Medicine in Baltimore and colleagues. The study is reported in Wednesday's issue of The Journal of the American Medical Association.

Specifically, the researchers report that serologic testing was performed on two thirds of patients with tick bites, and that 55% received prophylactic antibiotic therapy, sometimes before their test results were returned. Antibiotic therapy was also prescribed for 95% of patients with Lyme disease and 38% of patients suspected of having the disease, again many times before testing was completed.

Physicians treating tick bites "...are either unaware of recommendations against routine prophylactic antibiotic therapy, disagree with them, or find them infeasible in practice," the researchers write. "Increased educational efforts among physicians regarding appropriate use of serologic testing seems warranted, as well as anticipatory counseling of patients." They also call for more testing to determine if antibiotic therapy is effective.

In a related editorial, Dr. Alan G. Barbour from the University of California, Irvine, adds that patients may be confused by conflicting information they read in the media and Lyme disease brochures. "We can applaud the greater participation of patients and their families in decisions about their medical care," he writes, "but physicians may be too quick to accede to patients' demands in some instances." He concludes that "...for patients to be satisfied with the no-test, no-medicine option means that additional time must be taken to explain the rationale behind the decision."

SOURCE: The Journal of the American Medical Association (1998;279:206-210, 239-240)



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