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LE Magazine December 2000


MEDICAL UPDATES

Studies from throughout the world that can help you live longer

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December 2000
Table Of Contents

  1. Vitamin E succinate decreases human tumor cell division, but not in normal cells
  2. NAC delays age-associated memory impairment
  3. Low fat, soy protein diet with isoflavones decreases tumor growth
  4. Testosterone reduces neuronal secretion of Alzheimer's beta-amyloid peptides
  5. Tomato consumption protects DNA and immune system
  6. Anti-stress effects of DHEA
  7. Rye and soy vs. prostate cancer
  8. Selenium, lipid peroxidation and toxic metal levels
  9. Deprenyl inhibits tumor growth
  10. Curcumin prevents kidney disease
  11. Estrogen levels and Alzheimer's disease among postmenopausal women
  12. Sexual behavior and risks for prostate cancer
  13. Free vs. total PSA screening
  14. Fish oil vs. corn oil and the immune response

  1. Vitamin E succinate decreases human tumor cell division, but not in normal cells

    Full source: NUTRITION AND CANCER - AN INTERNATIONAL JOURNAL, 1999, Vol 35, Iss 2, pp 189-194

    Previous studies have shown that treatment of tumor cells with Vitamin E succinate, (natural form of vitamin E used by most Life Extension members) alone or in combination with radiation, reduced the growth of these cells more than that produced by individual agents. It is unknown whether Vitamin E succinate, alone or in combination with gamma-irradiation, would produce similar effects on normal cells. Therefore, a study compared the effects of Vitamin E succinate on cervical cancer, ovarian cancer, and lung cancer, with the effects on three human normal cells. The results showed that Vitamin E succinate treatment of cervical cancer cells for 20 hours caused inhibition of growth in a dose-dependent manner, but normal human cells treated similarly with Vitamin E succinate did not show this growth inhibition. Vitamin E succinate treatment for 20 hours also decreased cell division in all three tumor cell lines but, again, did not produce such an effect in any of the normal cells. As expected, gamma-irradiation decreased cell division in human tumor cells and normal cells, however, vitamin E succinate treatment for 24 hours before, during, and after irradiation for the entire experimental period further decreased cell division in human tumor cells but not in normal cells. This suggests that effects of Vitamin E succinate, alone or in combination with gamma-irradiation, are selective for tumor cells. Therefore, existing fear that antioxidants such as vitamin E may protect cancer cells from free radical damage during radiation therapy may not be justified.



  2. NAC delays age-associated memory impairment

    Full source: BRAIN RESEARCH, 2000, Vol 855, Iss 1, pp 100-106

    Mitochondrial oxidative damage is implicated in brain aging and in age-related neurodegenerative diseases. Since N-acetylcysteine (NAC) has recently been shown to prevent apoptotic death in nerve cells and protect mitochondria proteins from free radical damage in aged mice, a study investigated whether dietary administration of this NAC slows age-related memory loss. Mice received pellets containing 0.3% (w/w) of NAC. After 23 weeks of this diet, the NAC had partially restored the memory deficit associated with aging in mice. Moreover, the Lipid peroxide and protein carbonyl contents of the synaptic mitochondria were significantly decreased in the NAG-supplemented animals in comparison with their age-matched controls. The antioxidant properties and probable action on mitochondrial bioenergetic ability in the synaptic terminals may explain, at least partially, the beneficial action of NAC administration.



  3. Low fat, soy protein diet with isoflavones decreases tumor growth

    Full source: NUTRITION AND CANCER-AN INTERNATIONAL JOURNAL, 1999, Vol 35, Iss 2, pp 130-136

    Studies suggest that high intake of dietary fat is a risk factor for the development of prostate cancer. Soy protein has also been proposed to play a role in the prevention of prostate cancer, and one of the isoflavones in soy protein, genistein, inhibits the growth of human prostate cancer cells. A study evaluated whether altering dietary fat, soy protein, and isoflavone content affects the growth rate of a human prostate cancer in mice with compromised immune system. Dietary groups were: 1) high-fat group (42.0 kcal%) + milk protein, 2) high-fat group (42.0 kcal%) + soy protein + isoflavone extract, 3) low-fat group (12.0 kcal%) + milk protein, and 4) low-fat group (12.0 kcal%) + soy protein + isoflavone extract. After two weeks on these diets, the mice were injected with tumor cells and placed in separate cages to strictly control caloric intake. Results showed the tumor growth rates were slightly reduced in the group that received the low fat + soy protein + isoflavone extract diet compared with the other groups combined. The final tumor weights were reduced by 15% in the group that received the low fat + soy protein + isoflavone extract diet compared with the other groups combined. Thus, there were statistically significant effects on tumor growth rate and final tumor weight attributable to a low fat + soy protein + isoflavone extract diet.



  4. Testosterone reduces neuronal secretion of Alzheimer's beta-amyloid peptides

    Full source: PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA, 2000, Vol 97, Iss 3, pp 1202-1205

    Alzheimer's disease (AD) is characterized by the age-related deposition of beta-amyloid peptide aggregates in vulnerable brain regions. There is a lot of evidence implicating a central role for A beta in the pathophysiology of AD. A beta peptides are generated by A beta precursor protein (beta APP). Studies have reported that estrogen replacement therapy protects against the development of AD in postmenopausal women. Treating cultured nerve cells with 17 beta-estradiol has been reported to reduce the secretion of A beta peptides, suggesting that estrogen replacement therapy may protect women against the development of AD by regulating beta APP metabolism. Increasing evidence indicates that testosterone, especially bioavailable testosterone, decreases with age in older men and in postmenopausal women. A study reported that treatment with testosterone increases the secretion of the nonamyloidogenic APP fragment, spAPP alpha, and decreases the secretion of A beta peptides from nerve cells. The results raise the possibility that testosterone supplementation in elderly men may be protective in the treatment of AD.



  5. Tomato consumption protects DNA and immune system

    Full source: JOURNAL OF NUTRITION, 2000, Vol 130, Iss 2, pp 189-192

    Studies have suggested a role of tomato products in protecting against cancer and chronic diseases. Nine women, consumed 25 g tomato puree (containing 7 mg lycopene and 0.3 mg beta-carotene) for 14 consecutive days. The study evaluated whether the puree increased blood and lymphocyte carotenoid concentration, and whether this was related to an improvement in lymphocyte resistance to an oxidative stress of hydrogen peroxide after 5 min. The tomato puree increased blood and lymphocyte lycopene concentration and reduced lymphocyte DNA damage by up to 50%. beta-Carotene concentration increased in blood but not in lymphocytes after tomato puree consumption. When blood lycopene concentration and lymphocyte lycopene concentration were increased, the oxidative DNA damage was reduced, and vice versa. Thus, small amounts of tomato puree added to the diet over a short period can increase carotenoid concentrations and the resistance of lymphocytes to free radical stress.



  6. Anti-stress effects of DHEA

    Full source: BIOCHEMICAL PHARMACOLOGY, 2000, Vol 59, Iss 7, pp 753-762

    A study tried to determine if the adrenal steroid hormone dehydroepiandrosterone (DHEA) is an anti-stress hormone. Groups of rats were: 1) repeated immobilization stress (2 hours daily, for 60 days), 2) repeated immobilization stress (2 hours daily, for 60 days) plus daily administration of 5 mg DHEA/0.1 with DMSO, 3) daily administration of 5 mg DHEA/0.1 with DMSO alone, and 4) controls. Results obtained showed that repeated immobilization stress resulted in a significant (25%) inhibition in body weight gain, a significant increase in adrenal weight, an increase in glucocorticoid receptor (GR) in the liver, thymus, and spleen, decreased plasma triglyceride levels, and increased lipid peroxidation in the liver and heart as compared with control unstressed animals. However, DHEA administration resulted in a significant reversal in stress-induced inhibition in body weight gain, adrenal weight, GR levels in liver, thymus, and spleen, and lipid peroxidation levels in the liver and heart. In addition, animals treated with DHEA alone without stress showed a significant (15%) inhibition in body weight gain and an almost 60% decrease in blood triglyceride levels as compared with control unstressed animals. It was concluded that DHEA acts as an anti-stress hormone in rodents, by antagonizing the effects of repeated immobilization stress on total body weight, adrenal weight, GR levels, and free radical generation.


  7. Rye and soy vs. prostate cancer

    Full source: PROSTATE, 2000, Vol 42, Iss 4, pp 304-314

    Rye bran and soy protein delay growth and increase cell death of human prostate cancer in mice. A study investigated whether dietary intervention could inhibit tumor growth of an androgen-sensitive human prostate cancer. Prostate cancer cells were transplanted into mice. The animals were then put on different diets for 9 weeks. Tumors developed in 75% of the tumor-cell injected sites in animals fed a control diet (corn starch, sucrose, etc.). However, for animals given rye bran, tumors were seen in only 30% and for soy protein based diets 50% of the transplantation sites, respectively. The tumors that grew to palpable size in the rye and soy groups were smaller and secreted less PSA than those in the control group. In the rye and soy groups tumor cell death (apoptosis) was increased, but cell proliferation was unaffected. The addition of fat to the rye diet reduced its effect on prostate cancer growth. Therefore, factors in rye bran and soy protein may inhibit prostate cancer growth. The effect is more apparent for rye than for soy.


  8. Selenium, lipid peroxidation and toxic metal levels

    Full source: BIOMETALS, 1999, Vol 12, Iss 4, pp 353-359

    A study investigated the role of cadmium in the promotion of lipid peroxidation and the effect of selenium. Treatment of rats with cadmium resulted in a time- and dose-related accumulation of the metal ions in testes. Cadmium produced enhanced lipid peroxidation in testes. These cadmium-induced changes were accompanied by a significant increase of iron and copper, and a decrease of zinc in testes. However, treatment with selenium and cadmium at the same time reduced the cadmium-induced alterations in lipid peroxidation and essential metal levels. Thus, selenium was found to be effective in weakening the effect of lipid peroxidation induced by cadmium toxicity in the testes.


  9. Deprenyl inhibits tumor growth

    Full source: ANTICANCER RESEARCH, 1999, Vol 19, Iss 6B, pp 5023-5028

    L-deprenyl, a monoamine oxidase-B inhibitor; has been shown to reverse the age-related decline in sympathetic noradrenergic nerve supply and immune function in old rats and enhance T cell and NK cell activity in tumor-bearing rats. A study examined whether deprenyl treatment of old female rats with breast cancer could augment sympathetic nervous system and immune responses to inhibit the tumor growth. Rats were given up to 5.0 mg/kg body weight /day of deprenyl for 9 weeks. Relative to saline-treated controls, treatment with deprenyl reduced tumor growth, increased NE concentration, IFN-gamma production and percentage of the CD8+ T lymphocytes in the spleen. In the hypothalamus, deprenyl increased concentrations of catecholamines and indole-amine. These results suggest that deprenyl exhibits anti-tumor effects on spontaneous rat tumors.


  10. Curcumin prevents kidney disease

    Full source: BRITISH JOURNAL OF PHARMACOLOGY, 2000, Vol 129, Iss 2, pp 231-234

    A study investigated the effect of curcumin on artificially induced kidney disease in rats. Results indicated that treatment with curcumin prevented the kidney injury and restored kidney function. Treatment with curcumin significantly protected against proteinuria, albuminuria, hypoalbuminaemia and hyperlipidaemia. Curcumin inhibited the increase in urinary excretion of N-acetyl-beta-D-glucosaminidase (a marker of kidney tubular injury), fibronectin and glycosaminoglycan and blood cholesterol. The data also demonstrated that curcumin protected against kidney injury by suppressing free radicals and increasing kidney glutathione content and glutathione peroxidase activity (endogenous antioxidants). Curcumin also eliminated kidney microsomal and mitochondrial lipid peroxidation. The data suggest that administration of curcumin is a promising approach in the treatment of kidney disease.


  11. Estrogen levels and Alzheimer's disease among postmenopausal women

    Full source: NEUROLOGY, 2000, Vol 54, Iss 4, pp 833-837

    Although several studies have suggested that hormone replacement therapy lowers the risk of Alzheimer's disease (AD) among postmenopausal women, few studies have evaluated the relationship of endogenous estrogen levels and AD. A study investigated whether blood estradiol levels were related to the presence of AD among postmenopausal women between August 1997 and October 1998 not currently taking hormone replacement therapy. The results showed that those with AD had lower estradiol levels than did normal controls. Compared to estradiol levels greater than 20 pg/mL, women with AD were 4-6 times more likely to have levels lower than 20 pg/mL after adjusting for age, years of education, presence of a gene, ethnicity, and body mass index. The results suggest that estradiol levels may decline significantly in women in whom AD develops.



  12. Sexual behavior and risks for prostate cancer

    Full source: BRITISH JOURNAL OF CANCER, 2000, Vol 82, Iss 3, pp 718-725

    A study looked at the incidence of prostate cancer associated with sexual behavior with 981 men with pathologically confirmed prostate cancer and 1,315 controls. The result showed that prostate cancer risk was increased among men who reported a history of gonorrhea or syphilis (odds ratio (OR) = 1.6; or showed serological evidence of syphilis (OR = 1.8;. Risks increased with increasing occurrences of gonorrhea, rising to OR = 3.3 among subjects with three or more events. Frequent sexual encounters with prostitutes and failure to use condoms were also associated with increased risk. Syphilis, gonorrhea, sex with prostitutes and unprotected sexual intercourse may be indicators of contact with a sexually transmissible factor that increases the risk of prostate cancer.



  13. Free vs. total PSA screening

    Full source: BRITISH JOURNAL OF CANCER, 2000, Vol 82, Iss 3, pp 731-736

    A study tried to determine whether there was an advantage in measuring both free prostate-specific antigen (PSA) and total PSA as a potential screening test for prostate cancer. 247 men were verified as having died of prostate cancer, or had developed the disease, and 953 men did not develop prostate cancer were controls. The prostate cancer detection rate (sensitivity) over the 3 years (based on 14 cancers) increased from an estimated 95% using total PSA to 97% using free and bound PSA (that is, bound to alpha-antichymotrypsin which together with the free form is total PSA). Over a 6-year period (based on 41 cancers) a similar difference occurred (52% and 56% detection rates respectively). The conclusion was that there is no material advantage in adding free to total PSA in prostate cancer screening trials.



  14. Fish oil vs. corn oil and the immune response

    Full source: CANCER LETTERS, 2000, Vol 148, Iss 1, pp 27-32

    Studies support an association of chronic inflammation with the development of tumors. The colon contains a special type of lymphocyte (immune cell) population that may influence various stages of colon cancer development. In the colon, both inflammation and tumor development are affected by dietary factors. Diets high in n-6 fatty acids are considered proinflammatory and tumor promoting, but n-3 fatty acids are not. A study examined the proliferate response of lymphocytes in the colon, from mice fed a diet high in either corn oil or menhaden oil when they are grown in culture in the presence of proinflammatory cytokines (proteins). The lymphocytes from mice fed the high n-3 diet showed lower rates of proliferation following exposure to the inflammatory cytokines than lymphocytes from mice fed the high n-6 diet. Thus, diets high in n-3 fatty acids slow the inflammatory response in the colon as compared to diets high in n-6 fatty acids. Fortunately, the n-3 lipids do not inhibit the proper functioning of the immune system.





 



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