Issue: Jul 2003
In The News July 2003
New SARS dangers, expanded research on prostate cancer, T cell enhancement from L-theanine, antioxidants preventing nephropathy, elevated homocysteine and cancer.
As scientists discover more about the molecular characteristics of the virus that causes Severe Acute Respiratory Syndrome (SARS), some disturbing facts are emerging.
First of all, this is a hardy virus that can survive for days outside its host. Unlike the HIV or hepatitis C viruses, SARS has many potential transmission routes, which helps explain why so many healthcare workers have contracted it from their patients.
Since the SARS virus can survive on common surfaces at room temperature for hours or even days, people can catch this deadly infection without face-to-face contact with a sick person. One study showed the virus survived for at least 24 hours on a plastic surface at room temperature. This means it might be possible to become infected from touching a tabletop, doorknob or other object.
Disinfecting areas that you touch may be ineffective, as German scientists found a common detergent failed to kill the virus. Japanese scientists concluded that the virus could live for extended periods in the cold, suggesting it could survive the winter.
What has doctors most concerned, however, is that the SARS virus may easily mutate into a form that is resistant to anti-viral therapies. About six samples of the virus have been genetically unraveled and no two are exactly alike. This makes finding an effective vaccine or anti-viral drug therapy that much more difficult.
Physicians initially reported encouraging results with a multi-drug cocktail that included the anti-viral drug ribavirin and an anti-inflammatory corticosteroid drug. SARS patients who were given these drugs in the disease's early stages showed the best response. Initiating anti-viral drug therapy early in a viral disease process has proven efficacy. For example, if a person was exposed to the influenza virus, the FDA-approved drug Tamiflu® can prevent most infections if taken before symptoms manifest. If Tamiflu® is taken as soon as flu symptoms develop, the average duration of illness can be reduced.
As SARS strikes a growing number of people residing in China, however, it is becoming apparent that some individuals are dying even if they are given ribavirin. A group of French researchers has shown that ribavirin is not useful in killing a version of the SARS virus in cell culture. The Canadian government initially included ribavirin in its SARS protocol, but has withdrawn that recommendation pending further study.
There is so much contradictory medical information being released about SARS that it is not possible to publish a therapeutic protocol for SARS at this time. In the event a member of The Life Extension Foundation contracts SARS, please call the health advisor help line at 1-800-226-2370 and ask that a Life Extension physician return your call on an emergency basis.
The search for prostate cancer
risk factors continues
Researchers around the globe continue their quest to identify what classes of men are most at risk for prostate cancer. While it is well known that groups most at risk include older men, African-Americans and those with a family history of the disease, two recent studies explore the role of diet in the disease's development. A third study reveals a new potential predictor of prostate cancer.
A study conducted by Dr. Jacques Irani of La Miletrie University Hospital in Poitiers, France links obesity and an increased risk of prostate cancer. As reported in the April issue of British Journal of Urology International, obese men (those with a body mass index, or BMI, in excess of 30) were two and one-half times more likely to develop prostate cancer than those who were merely overweight (those with a BMI in the range of 25 to 29.9.)1 Irani's work is notable in that, unlike in prev­ious studies, researchers sought to eliminate the variables of age and race. Almost all of the 400 hundred participants were white men who were age-matched and received prostate treatment in the same hospital. The researchers noted, "In Western countries, where obesity has reached epidemic proportions, dietary modification and other public health measures directed at preventing obesity have the potential to reduce the incidence of many medical problems, probably including prostate cancer."
Obesity, in and of itself, might not be the only dietary factor to play a role in the development of the disease. A recent study led by Dr. Lillian Hsieh of Johns Hopkins University in Baltimore, Maryland found a link between total number of calories consumed per day and increased risk of prostate cancer. Men in the study who consumed the most calories (in the neighborhood of 2,600 calories per day) had almost four times the risk of developing the disease as those who consumed the least (half of whom consumed fewer than 1,100 calories per day). Hsieh and her colleagues, as reported in Urology, discovered it was the total number of calories that mattered and not the source of those calories, i.e., whether they came from protein, carbohydrate or fat. Furthermore, Hsieh's finding applied to both normal weight and overweight men. Thus, a man of average weight with a relatively high calorie intake could be at increased risk. Hsieh postulates there might be a connection between higher calorie intake and increased levels of insulin-like growth factor 1 (IGF-1), a metabolite of human growth hormone, which previously has been linked to prostate cancer. Hsieh and her research team maintain that in order to fully understand the role diet plays in the development of prostate cancer, further studies are needed, especially those that would measure, over time, men's weight and physical activity as well as calorie intake.
1. www.nhlbisupoort.com/bmi
Tea may boost the immune system
Recent research has demonstrated antioxidants in tea may inhibit the growth of cancer cells and help promote cardiovascular health. Now, a new study provides evidence tea may enhance the ability of gamma delta (gd) T cells in the human body to boost the immune system. According to the study, published in April in the Proceedings of the National Academy of Sciences, "tea…may prime human (gd) T cells that can then provide natural resistance to microbial infections and perhaps tumors." The (gd) T cells provide such resistance by releasing infection-fighting interferon.
The agent in tea responsible for this potential benefit is L-theanine, an amino acid that accounts for 50% of the dry protein weight of tea leaves. Theanine, in turn, is broken down by the liver into the (gd) T cell antigen, ethylamine, an alkylamine which is found in brewed tea as an intact molecule. The ethylamine, which is also produced by disease-causing agents such as bacteria, may then "serve to maintain (gd) T cells in a ready state, quickly able to respond to pathogens," the study concludes.
The pilot study, led by Dr. Jack F. Bukowski of Boston's Brigham and Women's Hospital and Harvard Medical School, followed 11 non-tea drinkers. These participants consumed five to six small cups, or approximately 20 ounces in total, of Lipton-brand black tea per day for a up to a four-week period. Each cup of tea was made by steeping a tea bag for five minutes in one hundred milliliters (3.3 ounces) of just-boiled water. A negative control group consisting of 10 non-tea, non-coffee drinkers drank 20 ounces of instant coffee per day. (While coffee contains caffeine, it does not contain theanine.)
Blood samples were taken from all participants before and after the experiment. When these samples were exposed to bacteria (to simulate an infection), analysis revealed the tea drinkers' post-test (gd) T cells produced an abundance of interferon when compared to pre-test specimens. Similar comparative analysis of the blood from the coffee drinkers revealed no such benefit.
While this pilot study was conducted with a relatively small sample and did not control for such variables as age, sex, race or dietary history, its powerful conclusion will undoubtedly result in further, more comprehensive analyses. Interestingly, Bukowksi's work does potentially point to yet another benefit of theanine, the little amino acid that could. The advantages of theanine have been chronicled in numerous Life Extension magazine articles. Theanine may enhance chemotherapy and reduce its side effects (Life Extension magazine, July 2002). It can help lower blood pressure and produce a calming effect in the brain, inducing feelings of relaxation and well-being (Life Extension magazine, January 2002). Also, it can protect one's ability to think as well as reduce symptoms of PMS (Life Extension magazine, October 2001).
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A new method of preventing contrast nephropathy
For years, many patients who elected to undergo coronary angiography risked prolonged hospitalization and renal deterioration as a result of the contrast agents used in the procedure. New research has revealed that the antioxidant acetylcysteine may help to prevent this potentially life-threatening toxic damage.
Contrast nephropathy is the deterioration of renal function following coronary angiography and intervention and has long been associated with prolonged hospitalization and adverse clinical outcomes. "Contrast nephropathy is a recognized complication of coronary angiography," wrote researchers in the February 5, 2003 issue of JAMA. "It is reported that 14.5% of patients develop a 25% increase in serum creatinine levels following cardiac catheterization. This problem assumes greater and greater importance with increased use of invasive radiological procedures to diagnose and treat coronary artery disease."
Although the disease occurs infrequently with normal renal function, its frequency increases with decreasing renal function, ranging from 5% in patients with mild renal insufficiency to as high as 50% in those with severe renal dysfunction and diabetes [JAMA 2003 Feb 5;289(5):553-8].
Previous studies have attempted to identify methods to reduce the incidence of contrast nephropathy, particularly in high-risk groups. Pretreatment with diuretics, such as furosemide or drugs thought to prevent vasoconstriction, such as calcium channel blockers have not provided clear benefit and may even be harmful [JAMA 2003 Feb 5;289(5):553-8].
Because acetylcysteine has well-established antioxidant properties, researchers speculate that it could in fact protect against oxidative-mediated contrast nephropathy. "Several randomized trials have demonstrated a 40% or greater decrease in the incidence of the disease among patients with chronic renal insufficiency who received contrast agents while undergoing computed tomography as well as cardiac catheterization," wrote Dr. Gary C. Curhan in JAMA. "However, other studies have found no benefit. These discrepancies may be due to differences in the timing and dose of acetylcysteine, total amount of contrast administered, characteristics of patients and the definition of contrast nephropathy."
In a recent prospective randomized clinical trial, researchers in Hong Kong reported on the use of acetylcysteine in patients undergoing cardiac catheterization. For that study, 200 Chinese patients with mild to moderate chronic renal insufficiency were randomly assigned to receive either placebo or acetylcysteine at 600 mg orally twice daily for a total of three doses prior to the procedure and one dose after the procedure. Serum creatinine levels were measured at admission, at 24 and 48 hours, and at day seven. Contrast nephropathy was defined as a greater than 25% increase in serum creatinine concentration within 48 hours after exposure to the contrast agent.
According to their results, contrast nephropathy developed significantly more frequently in the control group (12%) than in the acetylcysteine group (4%). In addition, the average length of hospitalization was 0.5 days shorter in the acetylcysteine group. Furthermore, the serum creatinine concentration decreased significantly after angiography in the acetylcysteine group, from 1.35 to 1.22 mg/dL at two days after the administration of the contrast medium. In the control group, the change in mean serum creatinine concentration was from 1.36 to 1.38 mg/dL and was considered "not significant." These results suggests that acetylcysteine may prevent contrast nephrotoxicity in patients with moderate chronic renal insufficiency undergoing coronary diagnostic and/or interventional procedures.
"Oral acetylcysteine is a safe, effective and inexpensive prophylactic treatment against acute renal dysfunction for patients with moderate chronic renal insufficiency undergoing coronary angiographic procedures with minimal adverse effects and at a low cost," the authors concluded.
Homocysteine and cancer
Homocysteine is a potentially toxic byproduct of the body's metabolism of the amino acid, methionine. Methionine is found in protein, particularly meat protein. Elevated levels of homocysteine are associated with an increased risk for heart attack and stroke.
New research indicates that elevated homocysteine in the blood is also associated with cancer. Researchers at the University of Utah and Chang Gung Hospital in Taiwan report that cancer cells release high amounts of homocysteine. They also discovered that levels of homocysteine track with cancer biomarkers. When cancer is treated with drugs that kill it, homocysteine levels fall. Researchers believe that homocysteine is indicative of rapidly-dividing cells, i.e., cancer cells. If verified by other researchers, homocysteine could be used in the future as a more sensitive biomarker than those presently in use since it only indicates the presence of living cancer cells, whereas traditional biomarkers appear to indicate both living and dead. For this reason, homocysteine levels may be a more reliable indicator of whether an anticancer treatment is working.
Research from the National Cancer Institute supports the notion that elevated levels of homocysteine may indicate that cancer is present. In a study on women with invasive cervical cancer, those with homocysteine levels greater than 6.31 micromoles per liter of blood were two to three times more likely to have the disease. Interestingly, a lack of folate did not increase the risk in this study, which may mean that other homocysteine-lowering vitamins such as B12, B6 or riboflavin are deficient in women with cervical cancer. Another possibility is that methylation (which lowers homocysteine and reduces the risk for cancer) is compromised in some other way. Similar studies have been done showing that homocysteine is elevated in colon cancer as well.
The laboratory test for measuring homocysteine levels is widely available. It is already well-known that lowering homocysteine can protect against heart attack and stroke.
-Terri Mitchell
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