The Durk Pearson & Sandy Shaw®
Life Extension NewsTM
From Vol. 4 No. 2 March 2001
LIPOSUCTION SUCKS AWAY INSULIN RESISTANCE TOO
We have long been interested in whether liposuction, a popular form of cosmetic surgery (218,064 liposuction procedures were reported in 1998 by board-certified plastic surgeons, dermatologists, and otolaryngologists), provides health benefits by reducing the body-fat load or altering fat distribution. An article in the January 17, 2001 Journal of the American Medical Association (pp. 266-268) suggests that this is the case. Particularly in large-volume fat-removal procedures, there have been reports of reduced insulin requirements in patients with diabetes and alterations in triglyceride levels. Large-volume liposuction involves 4-5 liters of material, with rates of serious or fatal complications (such as embolism and death) in the range of 0.02% to 0.3%. (Perhaps you can stay young by staying pretty. . . .)
MUSCLE LOSS IN ELDERLY ASSOCIATED WITH INACTIVITY AND TUMOR NECROSIS FACTOR-ALPHA
The muscle loss associated with aging leads to many problems, such as increased risk of falling and loss of strength. The mechanisms causing this muscle loss are not entirely understood. A new paper1 reports the results of a study of the hypothesis that TNF-alpha (tumor necrosis factor alpha) expression in human muscle increases with age and contributes to the wasting of muscle. The researchers also looked at the effect of resistance exercise on the expression of TNF-alpha.
TNF-alpha has been identified as a cause of cachexia, the wasting of skeletal muscle in cancer as well as in chronic infections, rheumatoid arthritis, and other chronic diseases. Loss of skeletal muscle may also result in an increase in peripheral insulin resistance and in adiposity. TNF-alpha is a substance released by adipose tissue that is believed to be a cause of insulin resistance. It is well known that TNF-alpha and other proinflammatory cytokines (such as interleukin 6) and markers of inflammation (such as C-reactive protein) increase with advancing age. C-reactive protein is a marker for atherosclerosis. In this study, the researchers followed eight frail elderly subjects who underwent muscle biopsies before and after a resistance exercise program. Five frail elderly subjects served as nonexercising controls.
The results showed that TNF-alpha was expressed in myocytes in skeletal muscle biopsies and was expressed at higher levels than those in young subjects. After three months of resistance exercise, both TNF-alpha mRNA and protein levels decreased, in concert with increases in strength and protein synthesis.
Of course, TNF-alpha has a number of other effects besides decreasing muscle tissue (otherwise what would be the point of having it). It has antiproliferative and antiangiogenic effects. It reduces free radical generation by cancer cells (a possible early mechanism in its antiproliferative effect). A number of agents are reported to inhibit the production of TNF-alpha, including pentoxifylline, cyclosporine, N-acetyl cysteine, corticosteroids, and thalidomide.2 17-Beta-estradiol has been reported to reduce TNF-alpha-mediated LDL accumulation in the artery wall.3
- Greiwe et al. Resistance exercise decreases skeletal muscle tumor necrosis factor alpha in frail elderly humans. FASEB J 15:475-482 (2001).
- James. AIDS Treatment News 221:2 (April 21, 1995).
- Walsh et al. 17-Beta-estradiol reduces tumor necrosis factor-alpha-mediated LDL accumulation in the artery wall. J Lipid Res 40:387-396 (1999).
MUSCLE STRENGTH MAINTENANCE WITHOUT EXERCISE IN HIBERNATING ANIMALS
We have long been interested in the mechanistic basis for the maintenance of muscle during hibernation despite profound inactivity. For example, black bears stay inside their winter den for five to seven months of the year, during which their body temperature drops to 4oC and they do not eat, drink, urinate, or defecate. They appear to engage in no physical activity, yet lose little muscular strength. It has been reported1 that during this long period of inactivity, in which humans would lose a predicted 90% of their strength, the black bears lose less than 23% of their strength.
During the study, the bears were anesthetized and then tested on an apparatus in which a metal brace held the bear's leg in a horizontal position, while a foot plate with a force transducer detected the evoked torque produced by the electrically stimulated tibialis anterior muscle.
The article1 suggests that there are three mechanisms by which skeletal strength and muscle protein can be conserved: by recycling urea nitrogen back into protein synthesis, by using alternative sources of protein, or by rhythmically stimulating the muscles (shivering and undergoing isometric muscle contractions). In a commentary in another journal,2 Hank Harlow, the study's lead author, notes that the bears recycle 90% of their urea nitrogen during hibernation, while people can recycle 14% of their urea. We would love to see further investigation of this mechanism to preserve muscle mass in the absence of exercise. Harlow's team plans to use fiber-optic probes to see if unnoticed exercise is going on in the dens, such as periodic activity "rather like a dog running in its sleep."
- Harlow et al. Muscle strength in overwintering bears. Nature 409:997(2001).
- Bradbury. If you go down to the woods today . . . , The Lancet 357:613(2001).
GOOD NEWS ON WEIGHT LOSS:
MORE ON EFFECTS OF CALCIUM ON ADIPOCYTE (FAT CELL) LIPID METABOLISM AND BODY-WEIGHT REGULATION
In the October 2000 issue of this newsletter, we discussed new findings that link higher levels of dietary calcium to reduced levels of body fat.1 The researchers first noticed this as a possible effect when studying obese African-Americans during a clinical trial on the antihypertensive effect of calcium. In a follow-up, the same researchers used epidemiological data from the NHANES III nutritional survey of Americans and found that there was an inverse relationship (in both men and women) between calcium intake and body fat. These researchers had previously shown that agouti, an obesity gene expressed in human adipocytes, stimulates Ca2+ influx and promotes energy storage in human adipocytes by stimulating the expression and activity of fatty acid synthase. In transgenic mice overexpressing agouti, a Ca2+ channel antagonist (nifedipine) for four weeks improved insulin resistance, platelet aggregation, and blood pressure, as well as decreasing lipogenesis (synthesis of lipids) in adipocytes.
A new study2 by Shi, Dirienzo, and M. Zemel has now reported the results of experimental tests of the hypothesis that suppressing 1,25-(OH)2-D (synthesized from vitamin D precursors) by increasing dietary calcium inhibits adipocyte Ca2+, thereby accelerating lipid catabolism and weight loss in calorie-restricted aP2-agouti mice. The same authors had recently reported that the calcitrophic hormone 1,25-(OH)2-D that has been shown to stimulate calcium influx in both vascular smooth muscle cells and pancreatic beta cells plays a role in the development of hypertension and hyperinsulinemia.
The new study examined the effect on fat and body weight of a low-calcium, calorie-restricted diet (0.4% as calcium), a high-calcium diet (1.2% of diet as calcium carbonate), and medium-dairy and high-dairy diets (1.2% or 2.4% calcium derived from nonfat dry milk, replacing 25% or 50% of protein, respectively). The bottom line was that the animals had a much greater body-weight loss on the high-calcium (calcium carbonate, 19% weight loss), medium-dairy from nonfat dry milk (25% weight loss), and high-dairy (29%)diets, as compared to only 11% body-weight loss on a calorie-restricted, low-calcium diet.
Although the basal-energy-restricted diet did not affect adipocyte lipolysis(breakdown of fats), the high-calcium diet caused a 77% stimulation of lipolysis, which was increased further by more than twofold in the medium-and high-dairy diet groups. All three high-calcium diets induced an increase in core body temperature. The authors suggest that this was caused by an increased expression of uncoupling protein 2 (UCP2), implicated in thermogenesis, in white adipose tissue, with an 80% increase reported on all three high-calcium diets.
These results are very exciting. However, as we warned in our previous discussion of the effects of calcium on body fat, do NOT take megadoses of calcium in an attempt to lose fat. In the case of calcium, RDA levels are reasonable. Excess calcium can cause kidney damage, calcium stones, and bone spurs. As has been known for some time (and was also indicated by the results in the new study), calcium from dairy products is more bioavailable than other forms of calcium.
- M. Zemel et al. Regulation of adiposity by dietary calcium. FASEB J 14:1132-1138 (2000).
- H. Shi, D. Dirienzo, M. Zemel. Effects of dietary calcium on adipocyte lipid metabolism and body weight regulation in energy-restricted aP2-agouti transgenic mice. FASEB J 15:291-293 (2001).
FAST VS. SLOW ALCOHOL METABOLISM AND THE RISK OF HEART ATTACK
The fact that, overall, moderate drinkers have a lower risk of heart attack than teetotalers has been getting around. Medical journals have agonized over the issue - gee, can we recommend moderate drinking to ourpatients when drinking is so politically incorrect? (Yes, but what is politically correct about having a heart attack?) The BATF (Bureau of Alcohol, Tobacco, and Firearms, the wonderful federal agency that brought us Ruby Ridge and Waco, among other things) is vehemently resisting the idea of allowing truthful information about the potential health benefits of moderate drinking on the labels of wine. However, the Competitive Enterprise Institute is litigating the issue on a First Amendment basis, and the BATF is likely to lose on this one.
The latest news on the magnitude of the effect of moderate drinking on the risk of heart attack may come as something of a surprise. The gene for alcohol dehydrogenase type 3 (ADH3) in humans comes in different versions (polymorphisms), which have now been shown to have a dramatic impact on the cardioprotective effects of alcohol.1 This enzyme determines how fast ethanol is oxidized to toxic acetaldehyde in the body.
The authors examined the ADH3 genotype in 396 patients with newly diagnosed cases of heart attack among men in the Physicians Health Study. Of these, 374 were matched with two randomly selected controls each, and the remaining 22 with one control each. The ADH3 genotype was determined for all subjects. The researchers looked at the relationship between the ADH3 genotype, level of alcohol intake, and plasma HDL levels in these men and in a similar group of women.
While moderate alcohol consumption was associated with a reduced risk of heart attack in all three of the ADH3 genotype groups, the men who were homozygous for the gamma-1 allele and who consumed at least one drink per day had a relative risk of myocardial infarction of 0.62 (a risk reduction of 38%), as compared with the risk among men who consumed less than one drink per week. Men who consumed at least one drink per day and were homozygous for the gamma-2 allele had the greatest reduction in risk (relative risk, 0.14, a risk reduction of 86%); these men also had the highest HDL levels. The relationship between ADH3 genotype, level of alcohol consumption, and HDL level was confirmed in an independent study of postmenopausal women.
The ADH3 polymorphisms are thought to affect the rate of alcohol oxidation. The authors suggest that their findings are consistent with the hypothesis that a slower rate of clearance of alcohol from the bloodstream enhances the beneficial effect of moderate alcohol consumption on the risk of cardiovascular disease. Approximately half the benefit of alcohol consumption on this risk can be explained by an increase in the HDL level. This is very important because it is much more difficult to increase HDL levels than it is to reduce excessive LDL levels.
Although the authors did not expect an effect on risk of heart attack among those who did not drink alcohol, they did observe a nonsignificant risk reduction among men who didn't drink and who were homozygous for the gamma-2 allele. It is interesting to note that about 10 grams (or approximately half a drink) of alcohol is manufactured in the body every day, so everybody is actually "drinking" a small amount of alcohol every day, whether or not they ingest it from exogenous sources.
- Hines et al. Genetic variation in alcohol dehydrogenase and the beneficial effect of moderate alcohol consumption on myocardial infarction. New Engl J Med 344(8):549-555 (2001).
NEW WEB SITE ON "ALTERNATIVE" MEDICINE
The U.S. National Institutes of Health has launched CAM on PubMed, a new subset of the National Library of Medicine's literature-search database. This subset allows users to search peer-reviewed articles on complementary and alternative medicine. CAM already contains about 220,000 citations from 1966 on. To search CAM-related citations, click on the "limit" function in the search interface, then select "Complementary Medicine" from the "subsets" pulldown menu. www.ncbi.nlm.nih.gov/PubMed - Source: The Lancet 357:729 (2001).
CERTAIN FRUITS CONTAIN INHIBITORS OF THE EPIDERMAL GROWTH-FACTOR RECEPTOR
A great deal of interest has developed concerning the family of epidermal growth-factor-receptor tyrosine kinases, which includes epidermal growth-factor receptor (EGFR), because many epithelial tumors (including breast cancer) express excess amounts of these proteins.1 A new study2 reports cyanidin and delphinidin, anthocyanins found in berries, grapes, and cherries, are potent inhibitors of the EGFR, shutting off downstream signaling cascades.
Anthocyanins are intensely colored compounds that contribute to the bright colors of many fruits. Depending upon individual diet, ingestion of several milligrams a day of anthocyanins would be expected. Extracts with particularly high levels of anthocyanins that are commercially available include bilberry and elderberry.
The authors tested whether the anthocyanidins cyanidin and delphinidin inhibited human EGFR extracted from cells of human vulva carcinoma. They found that these anthocyanidins potently inhibited the growth of the human large-cell lung-tumor xenograft cell line LXFL529L and, even more efficiently, the human vulva carcinoma cell line A431. Delphinidin exhibited similar levels of growth inhibition to that of (-)-epigallocatechin-3-gallate, a polyphenol that is structurally similar and found in green tea. The two anthocyanidins shut off the MAP kinase pathway activity downstream of the EGFR, a crucial signaling pathway in the regulation of cell proliferation.
The authors note that little is known about the cellular uptake, subcellular distribution, metabolism, and elimination of anthocyanins. As this study shows, however, it will be well worthwhile to learn a lot more about these colorful substances.
- See, e.g., Eisenhauer. From the molecule to the clinic - inhibiting HER2 to treat breast cancer. New Engl J Med 344(11):841-842 (2001).
- Meiers et al. The anthocyanidins cyanidin and delphinidin are potent inhibitors of the epidermal growth-factor receptor. J Agric Food Chem 49:958-962(2001).
PLASMA ASCORBIC ACID CONCENTRATION INVERSELY RELATED TO ALL-CAUSE MORTALITY
Because of the large human population differences in genetic factors, diet, and lifestyle, the protective concentration and potential size of the relation between ascorbic acid, cancer, and cardiovascular disease have varied between studies. A new 4-year prospective study of the relation between plasma ascorbic acid and mortality due to all causes, cardiovascular disease, ischemic heart disease, and cancer in 19,496 men and women aged 45-79 has been published.1
The subjects were part of a study known as EPIC-Norfolk, a prospective population study of 30,466 men and women aged 45-79 years, resident in Norfolk, UK, who completed a baseline questionnaire survey and of whom 25,663 attended a clinic. Because the researchers requested individuals to provide detailed dietary, biological, and other health data and to be followed up over the study period, they had about a 45% response rate. The participants were therefore not a random sample. Nevertheless, they were said to be closely similar to UK population samples with respect to such characteristics as blood pressure, lipids, and anthropometry, but with a lower proportion of smokers.
The results showed that plasma ascorbic acid concentration was inversely related to mortality from all causes and from cardiovascular disease and ischemic heart disease in men and women. Risk of mortality in the top ascorbic acid quintile (20%) was about half that in the lowest quintile. Ascorbic acid was inversely related to cancer mortality in men but not in women.
The researchers determined whether individual subjects took supplements and made some corrections for it - the inverse relation between ascorbic acid and all-cause mortality was consistent and independent of other risk factors, after exclusion of smokers and then after exclusion of supplement users. However, because of the varying compositions of dietary supplements (in addition to their content of ascorbic acid), it is not possible to correct for all the influences they may have.
Nevertheless, ascorbic acid (or, as is also possible, ascorbic acid and/or other nutrients contained in the high-ascorbate foods, largely fruits and vegetables) provided significant protection. The authors calculated that in this cohort, plasma ascorbic acid was specifically related to fruit and vegetable intake and that an increase of 20 micromol/L in plasma ascorbic acid concentration was associated with an increase of about 50 g daily (or one serving of fruit or vegetable) and about a 20% decline in death due to all causes, cardiovascular disease, and ischemic heart disease.
Ascorbyl palmitate is a powerful antioxidant synergist that delivers the benefits of vitamin C to fatty tissues that normally do not get it and has also been shown to suppress cancer promotion in mouse skin.
- Khaw et al. Relation between plasma ascorbic acid and mortality in men and women in EPIC-Norfolk prospective study: a prospective population study. The Lancet 357:657-663 (2001).
ESTROGEN AND ATHEROSCLEROSIS
There is still much that is not understood about the protective effects of estrogen against the development of atherosclerosis in premenopausal women and in postmenopausal women taking estrogen replacement. Part of the difficulty in interpreting the results of various studies is that there are now two known estrogen receptors, ER-alpha and ER-beta, which have diverse effects and are found in differing ratios in different tissues.
The reasons for conducting a study of the differences between the atherosclerotic protective effects of ER-alpha and ER-beta, the authors of a new study1 explain, is that while 17-beta-estradiol causes favorable alterations in lipoprotein metabolism, these changes appear to account for not more than 50% of the protection in humans. Moreover, several animal studies have shown full atheroprotection at 17-beta-estradiol doses that do not alter the lipid profile. These results have led to a focus on other effects of 17-beta-estradiol, such as direct effects on the vessel wall and on the processes involved in the inflammatory and fibroproliferative components of atherosclerosis, including endothelial permeability to LDL, LDL oxidation, cytokine and cell-adhesion-molecule expression, macrophage cholesterol homeostasis, vascular smooth-muscle-cell and neointimal proliferation and migration, calcification, and platelet adhesion and aggregation.
The results showed that in ovariectomized mice (female mice with their ovaries removed) that lack ER-alpha and lack ApoE (a cholesterol-carrying protein), the atheroprotection provided by 17-beta-estradiol is substantially abrogated, but it provided dramatic protection to mice who have ER-alpha but lack ApoE. This suggests that, at least in mice, 17-beta-estradiol's protection occurred largely, but not entirely, through the ER-alpha receptor.
In the mice with ER-alpha that received the most protection, the protection seemed to take place at an early stage, as the lesions in these mice at 4 months of age rarely progressed beyond small and uncomplicated fatty streaks. The researchers suggest that a possible factor in this early protection is nitric oxide, since multiple studies have shown that estrogen increases the synthesis of nitric oxide through increased expression and activity of endothelial nitric oxide synthase. They note that previous work by Rubanyi et al. has also shown that the basal release of nitric oxide is compromised in ER-alpha-deficient male mice.
Nevertheless, the high dose of 17-beta-estradiol used in the mice to demonstrate the reported effects also had significant adverse effects. The researchers report that "in addition to an overt enlargement of uteri, we found evidence of urinary obstruction in 24% and death in another 24% of the [had ER-alpha but lacked ApoE] mice treated with [17-beta-estradiol]." None of the mice that lacked ApoE and ER-alpha had the urinary or reproductive tract abnormalities. Moreover, the treated mice with ER-alpha but lacking ApoE also had foam-cell infiltration into subcutaneous macrophages (xanthomas, as are associated with hyperlipidemia in humans), while only two of 14 of the mice without ApoE or ER-alpha had such infiltration.
- Hodgin et al., "Estrogen receptor alpha is a major mediator of 17 beta-estradiol's atheroprotective effects on lesion size in Apoe-/- mice," J. Clin. Invest. 107(3):333-340 (2001).