|January 2000 |
What's Hot Archive
January 31, 2000
Psyllium lowers cholesterol
Psyllium and other soluble fibers have been found to lower total and LDL cholesterol when used in conjunction with low fat diets, decreasing risk of coronary artery disease.
Researchers at the University of Kentucky, Lexington analyzed eight different dietary studies to quantify soluble fiber's ability to lower cholesterol levels and its safety. The studies involved more than 600 participants. Subjects ate a low fat diet for the first eight weeks, then 384 subjects received 10.2 g psyllium daily and the other 272 subjects received a cellulose placebo. Those taking the psyllium decreased their total cholesterol by four percent and LDL cholesterol by seven percent. Participants tolerated the psyllium well.
Lead author Dr. J.W. Anderson equates each one percent drop in cholesterol levels to a two to three percent decrease in heart attack risk and projects people who take psyllium regularly could lower their risk of heart attack by approximately 20 percent. Soluble fibers, such as psyllium, decrease cholesterol-containing bile acid absorption and lower the liver's production of cholesterol. Anderson considers psyllium one of the most effective cholesterol-lowering fibers available, saying it is more potent than oat bran, guar gum or pectin. Researchers deem supplement safe for people with mild to moderate hypercholesterolemia when used in conjunction with a low fat diet. The findings were reported in the American Journal of Clinical Nutrition's February 2000 issue.
Anderson's previous research, reported in the journal last October, found psyllium lowered cholesterol and glucose levels in diabetics. Scientists in Singapore found minor cholesterol-lowering success last year using a product containing guar gum and psyllium. The subjects decreased their total cholesterol by 3.24 percent and LDL cholesterol by 5.45 percent, during a small, three month clinical trial. LDL cholesterol levels improved with compliance, dropping to more than seven percent in subjects who consumed at least half the treatment.
January 31, 2000
Vitamin D aids prostate cancer patients
Prostate cancer, one of the most common malignancies plaguing American men, often metastasizes to the bone, causing severe pain. Researchers found vitamin D supplements could relieve the pain, while improving muscle strength and quality of life. Researchers at the Veterans Administration Medical Center, the University of Kansas Medical Center and the University of Missouri-Kansas City found that a significant number of patients with metastatic prostate cancer develop vitamin D deficiency. The scientists speculate that the deficiency may be caused in part by less exposure to the sun, diet and older adults' decreased ability to synthesize the vitamin.
Sixteen patients with metastatic prostate cancer who had received hormonal therapy and had at least a six month life expectancy received a placebo for four weeks. The men, ages 47 to 83 years, were subsequently given 2,000 units of a commercially available liquid vitamin D supplement and 500 mg calcium daily for 12 weeks. At the start of the study and every four weeks, researchers measured calcium and vitamin D levels, assessed muscle strength by having the patients get up out of a chair and walk, and questioned patients about the pain they were experiencing. Four patients, or 25 percent, had less pain and 6 patients, or 27 percent, gained muscle strength after taking the supplements. Patients did not decrease narcotic intake.
The body requires vitamin D to keep bones healthy and strong. Deficiencies in older adults can cause muscle pain and weakness. Previous research has demonstrated that vitamin D inhibits prostate cancer cell lines in test tubes. Researchers concluded that vitamin D may be a useful addition for managing pain, and improving muscle strength and quality of life but that more research was needed to determine an optimal dose.
January 31, 2000
Long life genes in some may hasten death for others
Researchers working with fruit flies have found gene mutations that extend the creatures' lifespans and hope to locate similar life-extending genes in humans. However, a new study showed having the gene was not enough, surroundings and sex mattered. North Carolina State University researchers, using genetic mapping techniques, found 17 genetic variations which enabled some of the lab-bred flies to live longer, depending on their gender and environment. They recorded lifespans of flies raised on different diets and at high and low temperatures. They also evaluated how exposure to heat shock and starvation stress influenced longevity.
Ten of the mutations caused some flies to live longer and others to die sooner. The researchers used as an example one gene variation that extended females' lives if the flies survived a hot spell early in life, but caused earlier deaths if the flies lived at a constant room temperature. Male flies with the same genetic variation, exposed to the same environment, experienced no change in longevity. "Many association studies have been done for candidate genes affecting characters like alcoholism and Alzheimer's disease," said researcher Trudy Mackay. "Different researchers get different answers. One might wonder if the environment accounts for some of these disparities.
A different study at the University of Minnesota in St Paul found environmental or gender differences had little effect on longevity-associated genetic variations. But an Italian study found a genetic variation that makes men but not women live longer. Mackay said studies of other animals, including humans, shows that environment and gender alter the effects of genes. She recommends further research, using different strains, to determine if the results can be generalized.
January 29, 2000
Enzyme implicated in asthma
Asthma effects approximately 4% of Americans, or nine million people in the United States. It is characterized by acute and chronic inflammation of the airway passages and their increased responsiveness, resulting in bronchial constriction. This leads to frightening attacks during which the sufferer experiences difficult breathing often accompanied by coughing and wheezing. Although asthma occurs most often in children and young adults, over half outgrow the disease, however the disease is affecting an increasing number of people.
Researchers are currently exploring how inflammatory cells are recruited to the airways. In an article which will appear in the February 1, 2001 issue of the journal Nature Immunology, researchers from the United States and Japan use a guinea pig model of the disease to demonstrate that the enzyme cytosolic phospholipase A2 (cPLA2) causes the infiltration of inflammatory cells (eosinophils) to the area and the increased responsiveness of the airway that follows.
Previous research published in the same journal as well as in the journal Nature had implicated cPLA2 in other lung syndromes. By targeting the enzyme, drugs can be developed that block both the inflammation and hyperresponsiveness of the airway that exist in asthma. This offers hope to the millions of people afflicted with this often lifelong disease.
January 28, 2000
Oat bran and other fiber decrease prostate cancer risk
Canadian researchers have discovered diets high in soluble fiber, such as that provided by oat bran and legumes, may help ward off prostate cancer.
During a four month period, fourteen healthy men with elevated blood lipid levels ate either a diet high in soluble or insoluble fiber amounting to 25 to 30 g of dietary fiber per 1000 kilocalories. Insoluble fiber is the type of fiber found in wheat bran and breads. Those eating soluble fiber had lower prostate specific antigen (PSA) levels, than those eating the insoluble fiber diets. Prostate specific antigen, or PSA levels are an indicator of prostate cancer risk.
Male hormones stimulate prostate tumor cell growth. The body produces the hormones from cholesterol and excretes them through the bowel. Soluble fiber increases hormone removal through digestion. Scientists thought the added excretion would decrease prostate stimulation and lower PSA levels. While more hormones were excreted in the men's feces and PSA levels dropped, blood levels did not decrease.
"Thus our overall hypothesis that soluble fiber may have an effect appears to be correct, though we do not have an exact indication of the mechanism yet," said lead author David Jenkins, a professor at the University of Toronto. "Though it remains to be seen whether over the course of a lifetime this dietary factor makes an important difference, these results go along with existing advice to eat more vegetable foods and less animal products in the prevention of prostate cancer. It is further reinforcing what has been general advice about fiber, but perhaps gives another reason for taking it."
January 28, 2000
Peptide blocks prostate cancer spread
A peptide developed by scientists at the University of Michigan stopped the spread of prostate cancer in rats and limited primary tumor size. The peptide decreased lung metastasis even when the prostate tumor had grown large before surgical removal.
Scientist Donna L. Livant, Ph.D., changed one amino acid in a peptide chain found in fibronectin, a blood protein which branches out when tissue is injured, stimulating surrounding cells to migrate and repair the damage. "Cancer is the price we pay for our ability to heal from wounds," Livant said. "When intact fibronectin stimulates cancer cells to invade, they can easily reach the blood or lymphatic system and metastasize or spread to other parts of the body."
The new peptide inhibited cancer spread in cultures of human and rat cancer cell lines. During animal experimentation, rats were injected with metastatic prostate cancer cells. Some received the new peptide three times a week, others did not. After sixteen days, tumors in the untreated rats were 2,000 times larger. Blood vessel density was ten times greater than in the treated rats. This is significant, because tumors need a steady blood supply to grow.
When prostate tumors were surgically removed, rats treated with the new peptide after surgery developed 99 percent fewer visible lung tumors and 95 percent fewer microscopic lung micrometastases than those that only received surgery. The treated rats showed no signs of toxic side effects from the altered peptide.
"There appears to be a biochemical 'on switch' controlling tumor cell movement, which may be activated by the defective receptor pattern of key receptors on cancer cells. Our goal is to learn how to use this new peptide to turn that switch off," said Livant. Use of the peptide could become the basis for new cancer treatments, if it proves equally effective in people.
January 28, 2000
Healthy diet boosts older women's immune systems
Healthy eating habits may spare older women the risk of declining immune function. Researchers at Penn State University found the immune systems of well-nourished women from ages 60 to 80 functioned as well as those of women decades younger.
The researchers recruited 75 older women, who did not have any chronic or acute inflammatory or medical problems, and 35 younger women between 20 and 40 years of age. The team excluded women from 41 to 59 years to avoid interference with hormonal changes during menopause that can alter immune function. They tested nutritional, protein, iron, vitamin B12 and folate status.
"Although previous studies had, for the most part, indicated a general age-related decline in immune function, our study suggests that, when nutritional and health status are maintained, the body's ability to defend itself against viruses, bacteria or tumor cells may not necessarily be affected with aging per se," said study leader Dr. Namanjeet Ahluwalia, assistant professor of nutrition at Penn State.
Researchers said additional research is needed to determine how intake of specific nutrients correspond with aging and immune response.
January 27, 2000
Olive oil may prevent colon cancer
Olive oil may offer protection against colon cancer, according to Spanish researchers working with rats. The animals that were fed diets rich in olive or fish oil experienced less cancer than their counterparts given safflower oil.
Scientists divided more than 100 rats into three equal groups, who received a diet high in either safflower oil, fish oil or olive oil. Then half of each group were given a cancer-inducing agent. Researchers evaluated tumor development, evidence of cancer precursors and fatty acid content at 12 and 19 weeks. Rats fed olive oil or fish oil had fewer polyps and other precancerous changes and fewer tumors than rats given safflower oil. Those on the olive or fish oil diets also had a significantly lower amount of a chemical involved in producing the inflammatory substance prostaglandin E, which has been shown to promote cancer during previous experiments.
Researchers said olive oil's components, such as squalene, flavonoids, and polyphenols, likely offer the cancer protection. They said it is unlikely that olive oil's primary ingredient, oleic acid, acts alone in generating the preventive effect, because it is found in foods which also contain oils and fats known to promote cancer. Beef, poultry and vegetable oils contain smaller amounts of oleic acid.
A German study reported in the journal Carcinogenesis in December, 1999, found monounsaturated fatty acids such as oleic acid to be protective. That study also determined that fish oil-derived omega-3 fatty acids seemed to prevent cancer cell proliferation. Earlier research has shown that dietary fat promotes cancer, but that it depends on the type and amount of fat.
January 27, 2000
Progestins combined with estrogen increase breast cancer risk
In a large (46,355 subjects) study published in the Journal of American Medical Association, estrogen replacement with the concomitant administration of progestins was found to increase the risk of breast cancer.
Previously, when 90% of the world's data concerning hormone replacement and breast cancer was analyzed, it was determined that breast cancer risk increased with longer, recent use of HRT. These findings were more prevalent in lean women and with those who had less clinically advanced tumors. It was not determined what influence improved diagnostics had on these findings.
In the current follow up study, data from twenty-nine american screening centers was analyzed between the years of 1980 to 1995. A total of 46,355 postmenopausal women were studied, with an average age of fifty-eight. Data was obtained by responses to questionnaires.
Many women take progestins along with estrogen in order to lower the risk of uterine cancer associated with estrogen replacement. The women studied who took estrogen alone experienced a 20% higher incidence of breast cancer. However, women taking estrogen with progestin experienced a 40% higher rate. These rates were similar for women who received annual mammograms and for those who did not, but were not valid for overweight women. According to the study authors, with every year of HRT, the risk of breast cancer increases: 8% for those using an estrogen-progestin combination and 1% for those using estrogen only.
Concerning these findings, JAMA editorial writer Walter Willett remarked that, ``Although post-menopausal hormone use has important benefits, the study ...highlights the potential hazards and uncertainties that accompany such use."
"The commonly held belief that aging routinely requires pharmacological management has unfortunately led to neglect of diet and lifestyle as the primary means to achieve healthy aging."
January 27, 2000
Gene therapy may prevent repeat bypass surgery
Up to half of all bypass surgeries fail within ten years due to reblockage of the blood vessels. A new gene therapy shows promise as a treatment to keep the arteries open. Researchers at England's Bristol Heart Institute found the gene therapy procedure worked at two different levels: it hindered production of a molecule that promotes cell overgrowth in the inner walls of the new vessel and it eliminated those cells that did form. New vessels are prone to reblockage from postoperative clot development and the overproduction of cells within the new vessel's walls. More than 600,000 bypass surgeries are performed annually in the United States, with twenty percent being repeat procedures due to new blockages. "If we could find a way to block that abnormal layer from growing, it could make the grafts last longer and delay or even avoid second bypass surgeries," said lead author Sarah J. George, Ph.D.
Targeting matrix metalloproteinases (MMPs) that encourage the growth of cells in a process similar to the formation of scar tissue, the researchers increased release of a molecule called tissue inhibitor of metalloproteinase (TIMP-3) from human veins before culturing. Within two weeks, the TIMP-3 molecule decreased abnormal cell growth by 84 percent and did not spread to surrounding tissue. The researchers said their study is the first using human tissue to demonstrate that increased production of a TIMP-3 can decrease undesirable vessel thickening. Using a similar method on live pigs, the researchers found that within 28 days after administrating the molecule, it had reduced cell proliferation in bypass grafts by 58 percent. "This study shows the potential of this type of gene therapy for reblockage of vessels following bypass surgery," George said.
January 26, 2000
Number of Cardiac Deaths Peak on Mondays
Mondays may pose a higher risk for coronary heart disease deaths, which may be associated with drinking alcohol.
Members of Scotland's National Health Service tallied the number of people dying on each day of the week from 1986 through 1995 and compared the numbers from coronary heart disease with deaths from other causes. Based on coronary heart disease deaths involving 91,193 men and 79,051 women, researchers found a peak on Mondays, 3.1 percent above the daily average, for men and women who died outside the hospital and had not had previous hospital admissions for the condition. Deaths from other causes rose on Thursday and Friday and peaked on Saturday, at 1.1 percent above the daily average.
Patients with previous hospital admissions for coronary heart disease did not have an increased rate of dying outside the hospital, attributable to either their current medical regimen or their ability to recognize cardiac symptoms and immediately seek medical care. The records indicated an increase in hospital admissions for nondependent alcohol abuse were higher Friday through Sunday. The authors said that the Monday spike in deaths may be partly due to people drinking more during the weekend, which warrants further study. However, they acknowledge that other factors, such as work-related stress, may contribute.
Previous studies have found cardiovascular disease and death associated with binge drinking and alcohol withdrawal. A recent Russian study found higher cardiovascular deaths on weekends and Mondays, linked to binge-drinking patterns. Other studies determining if an increased risk exists on different days of the week have produced mixed results.
January 26, 2000
Lowering copper levels blocks cancer spread
Knowing that cancer cells require copper to create new blood vessels, researchers lowered copper levels in a small group of advanced-cancer patients, halting most tumor progression . Researchers at the University of Michigan found they could stop the growth of tumors and spread of cancer to new sites by depriving the body of copper. Doctors kept the copper levels of six patients with advanced cancer at one-fifth normal for more than 90 days. Within four to six weeks, patients taking the copper-lowering drug tetrathiomolybdate (TM) lowered their copper levels 20 percent. Patients tolerated the drug and decreased copper levels with no side effects. Five of the six participants showed no growth of existing tumors and did not develop any new tumors. One of the tumors in the sixth patient progressed, but the others did not. Twelve patients in the original study group could not reach or keep the lower copper levels due to progression of the cancer.
Lowering copper levels with an inexpensive drug could block a tumor's ability to form new blood vessels, a process called angiogenesis. Other angiogenesis inhibitors now under study are limited to combating only one form of cancer. Scientist began the study to determine if TM, normally used to treat a rare genetic disorder, could effectively lower copper levels in cancer patients. "What began as a scientific hunch now appears to have potential as a simple but effective general antiangiogenesis strategy," said Dr. George J. Brewer. "We are proceeding with a clinical trial aimed at accelerating TM-induced copper reduction and assessing its effect on advanced-stage cancer. Later this year, we hope to test this approach in 100 patients with five types of less advanced cancer."
Researchers believe that the sooner TM treatment begins, the better the results will be.
January 24, 2000
New Cancer Research Offers Promise in Preventing Metastasis
For the first time researchers have documented the initial steps taken by cancer cells to organize into tumors. The findings support current theories using angiogenesis inhibitors to fight the disease. The research also is the first to show that the inhibitors might also prevent cancer cell survival.
Working with rodents, Duke University researchers found that cancer cells metastasizing, or forming tumors at distant sites, communicate with existing blood vessels, migrate toward them and, with just hundreds of cancer cells present, create new blood vessels. Scientists previously thought millions of cancer cells existed before a new blood supply was generated.
By modifying the cancer cells to make them glow, the scientists were able to watch their behavior. After injecting the cancer cells into rodents, the researchers saw three or four surviving cancer cells reach out toward existing blood vessels within the first few days. By day eight, the cancer cells numbered 100 to 300 and had fully functioning new blood vessels. When the scientists injected an angiogenesis inhibitor at the same time as the cancer cells, all the cells died without communicating with existing blood supplies. When the inhibitor was withheld, a few cells always survived and started making a tumor.
"What we saw in our study was a mutual attraction between the growing tumor and the nearby blood vessels," said principal investigator Mark Dewhirst. "Now we need to identify what the attractants are, and that might give us new targets for therapies."
The team used a shortened, inactivated version of the protein receptor for vascular endothelial growth factor. The exact pathway the inhibitor takes is still under study, but the scientists said blocking the entire pathway produced "striking" results, stopping the cancer cells from taking root. Clinical trials using angiogenesis inhibitors are under way to determine their ability to thwart recurrences.
January 24, 2000
New Procedure Relieves Angina
Doctors in Chicago are investigating the use and safety of a new heart procedure in the hope that it will relieve patients' angina, or chest pain, by stimulating blood flow. More than seven million Americans suffer from chest pain due to coronary artery disease. Annually, about 80,000 Americans who are not candidates for traditional interventions, such as bypass surgery or angioplasty, develop the heart condition.
Rush-Presbyterian-St. Luke's Medical Center physicians have begun performing percutaneous myocardial channeling (PMC) on a limited number of patients. The heart catheterization technique begins much like angioplasty, with a catheter inserted in the femoral artery that is threaded to the heart. But during the new procedure, doctors use a rotating surgical blade to create 15 to 20 channels in the heart's inner walls. They believe the channels will stimulate growth of new blood vessels, which will bring needed oxygen and nutrients to the heart muscle. The device also allows doctors to remove a sample of heart tissue for further study. PMC is done under local anesthesia and takes about 90 minutes to complete. Patients generally go home the next day.
"If successful, myocardial channeling will add to our repertoire of therapies we can offer patients who are suffering from severe chest pain," said Dr. Gary L. Schaer, director of the cardiac catheterization laboratory at the Rush Heart Institute.
January 24, 2000
An old coronary procedure offers new hope for older patients
Developed in the 1950s but falling out of favor as newer treatments became available, coronary endarterectomy has reemerged to help patients with advanced coronary disease who are ineligible for bypass surgery.
During endarterectomy surgery, doctors open the chest, cut into the artery and eliminate the blockage. Unlike bypass surgery, they do not replace diseased vessels. Often after a bypass, new arteries can become clogged, and patients develop painful angina. But due to the vessels' poor condition, doctors are unable to perform additional grafts. While evaluating a new technique called transmyocardial laser revascularization (TMR), the doctors wondered if some patients could benefit from coronary endarterectomy. "Our concern was that people who might benefit from [coronary endarterectomy] might end up getting newer procedures whose benefits have not yet been determined," said Dr. Thoralf M. Sundt III, an associate professor of cardiothoracic surgery at Washington University in St. Louis.
Researchers investigated the outcomes of 177 patients, ages 39 to 83 years, who underwent this procedure between 1986 and 1997. Information was obtained three months to 11.5 years after the procedure, by telephone and written questionnaires. Eleven patients died of a heart attack within one month of the coronary endarterectomy. Participants had an operative morality rate of six percent, compared with 4.5 percent for bypass patients. The coronary endarterectomy patients' five year survival rate was 75 to 76 percent, depending on which artery the procedure was performed, and more than 70 percent had no chest pain.
"These complication and survival rates were quite satisfactory," Sundt said. "So we concluded that coronary endarterectomy can be performed with an acceptable risk and that it should be applied in a selective manner to patients whose vessels are not otherwise graftable. It therefore should be considered as an alternative or supplement to the use of novel technologies."
January 18, 2000
Long-term alcohol use may block body's ability to respond to stress
Drinking alcohol over a long period of time can "blunt" a person's ability to respond to stress, according to researchers at Rutgers University. The scientists define stress as more than a feeling of pressure or tension. Whether responding to a real or perceived threat, the body responds with a series of physiological steps to bring the body back to a state of biochemical and physiological balance. The hypothalamus secretes corticotropin-releasing factor, considered the "central stress hormone," which prompts the release of adrenocorticotropin and corticosteroids, chemicals that redirect nutrients to parts of the body that are facing the threat, preparing the body for "fight or flight." Chronic stress keeps the body in this state of heightened alert and suppresses immune system function.
Working with rats, the scientists found exposure to alcohol caused a drop in the hormonal and neuronal stress response. The rats exposed to alcohol vapors that simulated long-term drinking by humans had lower adrenocorticotropin and corticosteroids levels, while rats not exposed maintained normal levels.
"People who abuse alcohol have all kinds of health-related problems," said lead author Catherine Rivier. "What we showed here is that, in an animal model, the body loses part of its ability to respond to additional stressors. Alcoholics may therefore become unable to activate their stress axis appropriately when they are faced with a challenge, and that can be damaging. In this study, we tried to understand why this axis becomes blunted, why its activity becomes diminished."
January 18, 2000
New Blood Vessels Skirt Clots in Leg Arteries
The arteries in the legs of patients with intermittent claudication narrow, preventing blood flow which deprives the legs of oxygen and causes pain. Although doctors sometimes can open the blockage with bypass surgery or angioplasty, a new medical treatment may bring patients relief.
Researchers at Duke University Medical Center and the University of Michigan are testing a new angiogenesis growth factor, called recombinant basic fibroblast growth factor, which they expect will create new blood vessels or improve the function of small collateral vessels the body has already produced to supply areas deprived of nutrients by the blockage. Similar drugs have been found, during clinical trials, to help patients with clogged coronary arteries. Researchers say growing new arteries in the legs may be even easier, because circulation in the legs is less complicated than that in the heart. "Potentially, this investigational drug may increase blood flow to the legs, which would increase exercise capacity and improve patients' quality of life," said Duke cardiologist Dr. Brian Annex. The growth factor has promoted the development of blood vessel cells in a test tube, but how it will work in the human body remains to be determined.
"The agent could be going to the muscle that is starved for oxygen to help produce new vessels around the blockage or it could be making collateral vessels that already exist work better." Annex said.
To find out, the researchers will inject the drug twice, one month apart, into the femoral artery, near the hip bone, of 180 randomly selected patients whose condition is too advanced for traditional treatments. Scientists will assess the subjects' ability to walk and exercise, and their quality of life during the following six months.
January 18, 2000
New form of Colon Cancer May Require Different Treatment
Not all colorectal cancers are alike. Researchers have discovered a second, less deadly form of the cancer, which may allow some colorectal cancer patients to forgo chemotherapy.
Scientists at the University of Toronto and Mount Sinai Hospital's Samuel Lunenfeld Research Institute evaluated information and tumor samples from more than 600 colorectal cancer patients under age 50, treated between 1989 and 1993 in Ontario, Canada.
The research found that cancer cells in 17 percent of the patients had a genetic abnormality called microsatellite instability (MSI). These patients' cancers were less likely to spread to their lymph nodes, and the MSI patients experienced a five year survival rate of 76 percent. The other 83 percent had genetic mutations causing a chromosomal instability (CSI). The CSI patients had a five year survival rate of 54 percent. This is the first study to show that two different genetic pathways produce tumors that look the same but behave very differently. "These findings may ultimately lead to changes in the clinical management of colorectal cancer," said researcher Dr. Steven Gallinger. "This could allow us to withhold chemotherapy in these patients."
Now all colorectal cancer patients receive similar treatment. Researchers recommend continuing that practice. "We don't want people to stop taking chemotherapy tomorrow based on this," Dr. Gallinger said. "But we should have more definitive answers regarding treatment within a couple of years."
The research appeared in the New England Journal of Medicine. A related editorial by Dr. Kenneth Offit, of New York's Memorial Sloan-Kettering Cancer Center, pointed out that genetic testing is already being used in the diagnosis and management of other types of cancers, including leukemias, lymphomas and solid tumors. Offit expects that DNA testing will become more common with colorectal cancer when the results are shown to affect medical management of the disease.
January 12, 2000
Folate and Vitamin B12 Lower Cancer Risk
Eating three times the recommended daily intake of folate and vitamin B12 may lower cancer risk, according to a new Australian study. After evaluating chromosome damage in a group of 1000 participants, researchers found those eating foods containing folate and vitamin B12 had less wear and tear on their cells' genetic material. The results showed widely differing degrees of DNA damage between people of similar age. Scientists attribute the variance to poor diet, carcinogen exposure or genetic defects in repairing DNA. The cancer risk for people whose DNA damage exceeds average is two to three times that of people with little DNA damage. "Folate and B12 play a very important role in DNA synthesis and function," said lead author Dr. Michael Fenech, a scientist with CSIRO Health Sciences and Nutrition. "I believe between five and 10 percent of people eating a Western diet do not take [in] enough to optimize DNA repair and synthesis."
Meat, chicken, fish and organ meats contain high amounts of vitamin B12. Folate is prevalent in green, leafy vegetables and whole grains. Researchers found that giving supplements of folate and vitamin B12 for twelve weeks to subjects with large numbers of DNA defects decreased the subjects' chromosome damage by 25 percent. No change was noted in people with initially low levels of damage.
"We have found that people with above average damage to their DNA may reduce some of the damage by boosting their intake of these vitamins," Fenech said. "The message is that it is essential to take care of your DNA, as this should optimize your chances for longevity and reduced cancer risk."
Additional studies are under way to determine the ideal vitamin levels one would need to minimize DNA damage and to investigate a link between DNA damage and other age, diet and lifestyle related diseases.
January 12, 2000
Discovery of a Naturally Occurring Cancer Fighter
A potent new, naturally occurring protein halted tumor growth in mice by blocking the creation and development of new blood vessels. Researchers at Beth Israel Deaconess Medical Center, a teaching affiliate of Harvard Medical School, discovered the angiogenic inhibitor, called canstatin. The protein stops blood vessel production by causing cell death in dividing cells found in new vessels but not in nondividing cells in existing blood vessels.
Working with mice, the scientists found canstatin suppressed prostate cancer tumors as effectively as the angiogenic inhibitor endostatin. With renal cancer, canstatin halted tumor growth or shrank the cancer to as much as a quarter of the size of the tumors in the placebo-treated mice. "Tumors are highly dependent on new blood vessels for their growth, and canstatin appears to stop the division of endothelial cells as they begin multiplying to form new blood vessels," said researcher Raghu Kalluri, an assistant professor of medicine at Harvard Medical School. "The tumor stops growing because it doesn't get any new blood supply or nutrients."
The Beth Israel researchers have developed a series of proteins that stop the formation of new blood vessels. Canstatin, named for its capacity to fight cancer, was produced using recombinant Escherichia coli molecules and embryonic kidneys cells. Additional studies show canstatin appears to block more than one step in the new blood vessel production process. Kalluri expects canstatin will prove relatively easy to produce in sufficient quantities for human clinical trials. Research using human subjects may start in a year or two, possibly in conjunction with other treatments. "I do not believe any angiogenic inhibitor will be used as a single agent to fight cancer," Kalluri says. "They're potentially powerful drugs for controlling tumor growth, but for complete control of cancer, angiogenic inhibitors probably will have to be used in combination with existing therapies, such as radiation and chemotherapy."
January 12, 2000
Two Drinks a Day May Be Optimal Alcohol Intake
While alcohol intake can lower the risk of heart disease, it ups the chances of liver disease and cancer. Researchers at Brigham and Women's Hospital and the Veterans Affairs Medical Center in Boston investigated the amount a person can drink to reap benefits without incurring added cancer risk and determined two drinks to be an optimal amount.
Researchers came up with the amount after studying the cause of death for 3,216 men participating in the 5.5 year, 89,299-man Physicians' Health Study. Men consuming one to 14 drinks a week lowered their risk of death by 26 percent, without raising their cancer risk. Men who drank more than two alcoholic beverages per day increased their risk for rarer cancers, but still enjoyed the cardiovascular benefits. Previous studies have shown that drinking alcohol may contribute to liver disease, dementia and strokes caused by bleeding.
Researchers caution that drinking recommendations must depend on the individual and existing health conditions. Patients should discuss alcohol consumption with their doctor. Those with high blood pressure or diabetes might need to drink less, and anyone with liver disease or who is prone to alcoholism should abstain.
January 12, 2000
Recent Alcohol Intake Does Not Alter Heart Attack Outcomes
Alcohol intake prior to a heart attack does not alter a patient's complication rate or severity of heart damage, according to new studies.
Researchers from Harvard Medical School and other universities examined medical records at 64 medical centers and interviewed 2,161 patients who had a heart attack between August 1, 1989, and September 30, 1996, but did not receive therapy to dissolve the blood clot. The investigators found no significant difference in complications between the 18.5 percent who had consumed alcohol in the previous 24 hours with those who had not imbibed.
Complication rates also did not change for those who had a drink in the six hours preceding the cardiac event. In addition, scientists found no association between chronic alcohol use and complications, such as congestive heart failure or irregular heart rates. Previous studies have linked regular alcohol consumption with lowering the risk of death from coronary artery disease and the onset of a heart attack. Alcohol inhibits platelets from clotting, and the diameter of coronary arteries in moderate, long-term drinkers are larger than in nondrinkers. But alcohol can also depress the action of the heart, increase heart rate, cause chest pain in susceptible people and lower exercise tolerance. While other factors that prevent heart attacks on a long-term basis, such as aspirin use and exercise, have been shown to act in beneficial ways during a heart attack, researchers say this study shows recent alcohol intake does not change the severity, progression or complications following the cardiac event.
January 11, 2000
FDA Publishes Final Rule for Dietary Supplement Claims
After receiving comments from consumers, the US Food and Drug Administration has issued a final ruling addressing statements dietary supplement manufacturers can make about products. Citizen and industry feedback prompted the agency to expand what it considered acceptable. Consumers initially felt the FDA's definition of disease was too broad. They also persuaded the agency to let companies make statements about minor symptoms.
Without requiring prior FDA approval, manufacturers can make statements about a product's effects on body function or structure, health maintenance information and information concerning the relief of minor symptoms common during different life cycles, such as menopause, adolescence, pregnancy or aging. Examples of allowable statements include "relaxes you," "enhances muscles," "improves circulation" or "for hot flashes."
Claims that the supplement prevents, treats, cures, mitigates or diagnoses a disease must undergo an agency review. Companies cannot make implied or direct disease specific statements using the product's brand name, formulation, photos, vignettes, graphic designs or symbols. For instance, product literature cannot claim that a product "prevents heart attacks."
The FDA expects its ruling will help consumers choose products wisely, based on better information. It is part of an overall strategy to raise the level of confidence consumers have in the safety, labeling and composition of dietary supplements. The ruling should not interfere with product availability. Consumers may notice changes on labels.
Any company introducing a product after the rule takes effect next month will be required to comply, as will those companies seeking to make new claims for existing products. Small companies already marketing a product will have seventeen months to comply, others will have eleven months. Companies must continue to keep records to back up the claims, to notify the FDA of claims they make, and to include a disclaimer that supplements are not drugs and are not subject to FDA approval.
January 11, 2000
Human Papillomavirus Tests Helpful in Cancer Screening
Human papillomavirus (HPV) tests accurately identified many precancerous changes in the cervix of women during a recent study conducted by the National Cancer Institute (NCI). Scientists said the tests may be a useful screening tool in high risk populations. "Our findings suggest that HPV testing is a viable technology worthy of consideration in cervical cancer prevention programs," said the study's principal investigator, Dr. Mark Schiffman, an epidemiologist at the NCI.
Doctors have been aware for some time that certain types of sexually transmitted HPV cause most cervical cancers, which led researchers to evaluate testing for these virus types as a cancer screening tool. Researchers evaluated the use of two tests that detect HPV DNA in a country with a high incidence of cervical cancer. The 8,554 randomly selected Costa Rican women also received conventional diagnostic screening with Pap smears.
Using a standard of 1 picogram of HPV DNA per milliliter of solution, the Hybrid Capture II test accurately found 88 percent of the precancerous, high grade lesions and detected all cases of cervical cancer in the women studied. The test correctly identified and classified as negative 89 percent of the women who did not have high grade lesions or cancer. An older version of the test was less accurate.
Although researchers believe HPV testing can be a effective screening tool, they caution its usefulness may vary depending on the population, other available tests and cost. "Decisions on optimal methods of screening will probably have to be made on a regional or national basis and depend on health economic analyses," Schiffman said.
Other recent studies, including one in South Africa where the women obtained the samples themselves, found HPV testing to be a beneficial cervical cancer screening tool. Taiwan researchers found HPV tests helpful when used in conjunction with Pap smears.
January 6, 2000
Glucose metabolism and dopamine in brain
Chemical changes in the brain contribute to cognitive loss in older adults, according to researchers at the U.S. Department of Energy's Brookhaven National Laboratory and two universities. Although previous studies have shown dopamine activity decreases with age, the functional consequences remained unknown. This study showed for the first time that when dopamine D2 receptors decreased, so did glucose metabolism in areas of the brain that control problem solving, abstract thinking, multitasking, attention span, mood and impulsive actions.
Scientists recruited 37 healthy adults, age 24 to 86, and conducted positron emission tomography (PET) scans. Chemicals were injected to highlight receptors that transmit dopamine signals and regional brain glucose metabolism, which serves as a marker of brain function. After comparing the data, the researchers found age brought a deep decline in the ability to transmit dopamine signals, with people losing about six percent of their receptors during each decade between 20 and 80 years. Even after removing the effects of aging, the scientists found a significant correlation between the available dopamine receptors and brain function. "In this study, we have shown that age-related loss of dopamine, the brain chemical associated with pleasure and reward, slows metabolism in regions of the brain that are related to cognition. This finding may be helpful in developing interventions for age-related cognitive decline," said lead author Dr. Nora Volkow, Brookhaven's associate director for Life Sciences.
Additional study will be needed to explore therapeutic treatments to enhance dopamine function in seniors and to determine if those interventions relate to improved brain function.
January 6, 2000
Air Pollution Increases Cardiac Mortality
Scientists have long known that air pollution damages the environment. In addition, epidemiological studies involving thirty U.S. and world cities show higher cardiac and respiratory mortality rates and an increase in hospital admissions after exposure to short-term fine particulate air pollution. The specific cause remains under investigation.
Researchers from the Harvard School of Public Health, Brigham Young University and other sites have investigated the association between air pollution and the body's response. After a study a few years ago failed to indicate hypoxia as a cause, the scientists looked at autonomic nervous system changes to the cardiovascular system. Six elderly participants from the previous hypoxia study were recruited to wear ambulatory electrocardiograph monitors before, during and after exposure to highly polluted air. The seniors, plus a younger participant, were selected based on their having varying degrees of lung and heart conditions.
Subjects experienced increased heart rates and other alterations in heart beat. Other studies have linked elevated heart rates with high blood pressure, coronary artery disease and sudden death. Scientists concluded that changes in heart rate may contribute to the increased mortality after exposure to air pollution, but said more research, using larger population groups, is needed. The study was reported in the American Heart Journal.
In another Harvard study, researchers compared the relationship between high levels of air pollutants and discharges of implanted defibrillators. An implanted defibrillator shocks the heart if it detects a dangerous change in the heart beat. The scientists found patients experienced more episodes of potentially life-threatening arrhythmias when exposed to nitrogen dioxide, carbon monoxide, black carbon and the other fine particles.
January 4, 2000
Cardiac Deaths not Reduced by Stents
The New England Journal of Medicine recently published a study of 900 patients receiving balloon angioplasty. Approximately 50% received stents. While hospitalized there were no differences between the number of patients in each group experiencing complications, and between one and six months following implantation, people with stents were less likely to undergo another procedure to treat their atherosclerosis. Despite this, people in the stent group experienced a decline in blood flow and the death rate in the stent group was higher than in the group not receiving stents, though not statistically significant.
Dr Cindy L Grines, who led the research, stated "We should not be routinely using stents" in patients who have heart attacks. "Our goal is to make a patient survive through the heart attack," she stated, explaining that stents might reduce chances of survival. It is unknown what effect newer stents and using more blood-thinning medication in conjunction might have.
Another report published in the same issue of the NEJM, which studied 9,594 people who received treatment to open narrowed arteries between 1994 and 1997, showed that heart complications dropped by more than 20%, with people receiving stents increasing from about 14% to nearly 59%. Researcher Dr James B Rankin stated that the stents may account for some of the improvement. Nevertheless, the results show death and heart attack rates unchanged.
It appears that while reducing complications from angioplasty, stents do nothing to enhance survival.
January 4, 2000
Not Sleeping Could Prematurely Age Nightowls
Chronic sleep loss could accelerate the aging process and the onset of age-related illnesses, according to a recent study at the University of Chicago.
"We found that the metabolic and endocrine changes resulting from a significant sleep debt mimic many of the hallmarks of aging," said study director Eve Van Cauter, PhD, professor of medicine at the University of Chicago. While previous research focused on cognitive declines due to sleep loss, this study concentrated on physical changes. Scientists measured subjects' ability to control blood sugar levels, store energy from food and produce hormones.
Researchers constantly assessed 11 healthy, young men's heart rates and wakefulness during a sixteen day period. Subjects were allowed to sleep eight hours, then four, then twelve. Scientists noticed dramatic results indicative of advanced age or the early stages of Type 2 (adult-onset) diabetes during testing on days five and six of the four-hour sleep deprivation phase. Tests taken in the morning produced the most significant results. Participants took 40 percent longer than normal to stabilize blood sugar levels after a high-carbohydrate meal. Insulin secretion and response to insulin decreased approximately 30 percent, similar to the rates found in early diabetes. The subjects also secreted less thyroid stimulating hormone and more cortisol, especially afternoons and evenings. Elevated cortisol levels are associated with memory impairment and other age-related disorders in older adults. All abnormal findings returned to normal after the subjects were allowed to spend 12 hours in bed. Results surpassed normal levels when subjects slept more than eight hours nightly.
The authors noted that on average people sleep less these days, fewer than eight hours per night compared to nine hours in 1910. They concluded that sleep loss could result in long-term adverse health effects and increase the severity of age-related chronic disorders.
January 4, 2000
Large Glucosamine Sulfate Study Confirms Arthritis Benefits
A new, large study confirmed the dietary supplement glucosamine sulfate, which many people take to treat osteoarthritis, not only reduces symptoms but as a long-term therapy also prevents further joint deterioration.
"We have shown that a compound may be able at least to slow down the progression of osteoarthritis," said lead investigator Dr. Jean-Yves Reginster, Ph.D., of the University of Liege in Belgium.
During a three year period, researchers compared arthritic symptoms and average joint space widths in 212 randomly selected patients with osteoarthritis of the knee. Symptoms were evaluated every four months and weight-bearing x-rays were taken to evaluate joint space at enrollment and after one and three years. Half the patients took 1500 mg of glucosamine sulfate daily, and the balance took at pill with an inactive ingredient. Symptoms worsened and joint space narrowed in patients taking the placebo, while those taking the glucosamine sulfate experienced fewer symptoms and no further joint narrowing.
A second study presented at the same American College of Rheumatology conference identified what scientists described as glucosamine sulfate's novel mechanism to inhibit inflammation. The study showed glucosamine and N-acetylglucosamine's ability to prevent the formation of nitric oxide in cultured human cartilage cells by the inhibition of interleukin-1b and and tumor necrosis factor-a. N-acetyl glucosamine also suppresses interleukin-6 and COX-2 (a proinflammatory enzyme) induced by interleukin 1-b.
January 4, 2000
Vitamin D Supplements Help Prevent Osteoporosis
Researchers studying a small group of postmenopausal, African-American women found vitamin D supplements effective in preserving bone mass. The report published in the Journal of Clinical Endocrinology and Metabolism indicates black women typically have lower 25-hydroxyvitamin D and higher parathyroid hormone levels in their blood. Parathyroid hormone can stimulate calcium loss from bones. Researchers gave participants daily vitamin D supplements. At the end of three months, mean vitamin D blood levels had more than doubled, while parathyroid hormone levels dropped.
Earlier this year a National Institute on Aging (NIA) study found that undetected vitamin D deficiency contributed to hip fractures in postmenopausal women. Investigators at Brigham and Women's Hospital in Boston found that 50 percent of women with osteoporosis who were hospitalized with a hip fracture had undetected vitamin D deficiency, while only a small percentage of the women in the control group, hospitalized for elective hip replacement surgery, were deficient. The two groups of women were matched in postmenopausal years and had similar bone density of the spine and hip. The women with hip fractures exercised less and 50 percent had a vitamin D deficiency. More than a third had elevated parathyroid hormone levels. Most had calcium in the urine, indicating an inappropriate loss of the mineral.
Doctors anticipate the findings to spur additional research to determine the effectiveness of vitamin D supplements in preventing osteoporosis among African Americans.
"This new [NIA] research suggests that an adequate intake of vitamin D, which the body uses to help absorb calcium, may help women to reduce their risk of hip fracture, even when osteoporosis is present," observed Dr. Evan C. Hadley, with the NIA. "Osteoporosis leads to more than 300,000 hip fractures each year."
January 3, 2000
Alcohol-Free Red Wine Offers Same Cardiac Benefits
The elements that make red wine healthy for the heart appear to work just as effectively when consumed in nonalcoholic beverages. Flavonoids found in red wine, including catechin, have been associated with healthy hearts and decreased cardiac mortality. A recent Argentine study concluded that catechin had antioxidant properties, while another study found the flavonoid prevents platelets from clumping.
During a new University of California Davis study, researchers investigated how the body absorbs flavonoids from red wine and learned that drinking alcohol-free red wine raised heart-healthy catechin levels as much as the alcoholic beverage. The scientists removed the alcohol using a process that preserved all the essential flavonoids, including catechin. They reconstituted the samples, half with water and half with alcohol, bringing alcohol content up to the normal 13 percent found in red wine. The same subjects drank 120 mL of the alcoholic or nonalcoholic wine in random order on different days. Baseline and six additional blood samples were drawn during eight hour periods, following consumption of the beverages.
Blood levels of catechin rose sharply in both groups for the first three hours after drinking the beverages. But blood levels stayed higher longer when participants drank the nonalcoholic wine than when they consumed the alcoholic drink. Researchers speculate that the alcohol caused faster excretion or metabolization of the catechin and concluded that alcohol does not add any additional benefit to red wine's catechin.
January 3, 2000
Multiple Nutrients Promote Bone Health
In addition to calcium, British researchers have found that magnesium and potassium contribute to stronger bones in middle-aged women. The study compared bone density to dietary intake in 62 healthy Scottish women who had taken part in a previous osteoporosis study. For this research, scientists measured bone mineral density of the femoral neck and lumbar spine, and markers of bone formation and dissolution in the urine and blood. The forty-five to fifty-five year old women compiled a detailed diet summary, listing foods they had frequently consumed during the past twelve months, during childhood and as young adults.
Scientists found that women eating the most fruits and vegetables had higher bone mineral density and less bone loss. Current magnesium and potassium intake was associated with higher total bone mass. Women who ate large amounts of fruit during childhood had a higher bone mineral density in their femoral neck bones during midlife than their counterparts who ate little or moderate amounts of fruit as youngsters. Scientists also found intake of a moderate amount of alcohol improved bone health.
Researchers concluded that fruits and vegetables play an important role in the prevention of osteoporosis. Dietary sources of magnesium and potassium include baked potatoes with skin, green peas, bananas and enriched cereal.
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