Does DHEA supplementation affect muscle mass?

Watson R.R.; Jiang S.
USA
Expert Opinion on Investigational Drugs (United Kingdom), 1996, 5/12 (1725-1728)

DHEA (dehydroepiandrosterone) production declines dramatically with increasing age in people as they loose muscle mass. Animal studies have not shown that DHEA replacement affects body or muscle weight in animals, but does reduce lipids and reduces oxidation, increased with ageing. One research group has shown that growth hormones increase while others decrease during DHEA supplementation of older people. However, DHEA's effect on muscle mass in humans is unclear. DHEA supplementation does restore DHEA levels without apparent toxicity.

Regulation of protein turnover by glutamine in heat-shocked skeletal myotubes

Zhou X.; Thompson J.R.
J.R. Thompson, Department of Animal Science, University of British Columbia, Vancouver, BC V6T 1Z4 Canada
Biochimica et Biophysica Acta - Molecular Cell Research (Netherlands), 1997, 1357/2 (234-242)

Skeletal muscle accounts for approximately one-half of the protein pool in the whole body. Regulation of protein turnover in skeletal muscle is critical to protein homeostasis in the whole body. Glutamine has been suggested to exert an anabolic effect on protein turnover in skeletal muscle. In the present work, we characterized the effect of glutamine on the rates of protein synthesis and degradation in cultured rat skeletal myotubes under both normal and heat-stress conditions. We found that glutamine has a stimulatory effect on the rate of protein synthesis in stressed myotubes (21%, P < 0.05) but not in normal-cultured myotubes. Glutamine shows a differential effect on the rate of degradation of short-lived and long-lived proteins. In both normal-cultured and stressed myotubes, the half-life of short-lived proteins was not altered while the half-life of long-lived proteins increased with increasing concentrations of glutamine in a concentration-dependent manner. In normal-cultured myotubes, when glutamine concentration increased from 0 to 15 mM, the half-life of long-lived proteins increased 35% (P < 0.001) while in stressed myotubes, it increased 27% (P < 0.001). We also found that glutamine can significantly (P < 0.001) increase the levels of heat-shock protein 70 (HSP70) in stressed myotubes, indicating that HSP70 may participate in the mechanism underlying the effect of glutamine on protein turnover. We conclude that in cultured skeletal myotubes the stimulatory effect of glutamine on the rate of protein synthesis is condition-dependent, and that the inhibitory effect of glutamine on the rate of protein degradation occurs only on long-lived proteins.

Glutamine: From basic science to clinical applications

Ziegler T.R.; Szeszycki E.E.; Estivariz C.F.; Puckett A.B.; Leader L.M.
USA
Nutrition (USA), 1996, 12/11-12 Suppl. (S68-S70)

Glutamine (Gln) has been one of the most intensively studied nutrients in the field of nutrition support in recent years. Interest in provision of Gln derives from animal studies in models of catabolic stress, primarily in rats. Enteral or parenteral Gln supplementation improved organ function and/or survival in most of these investigations. These studies have also supported the concept that Gln is a critical nutrient for the gut mucosa and immune cells. Recent molecular and protein chemistry studies are beginning to define the basic mechanism involved in Gln action in the gut, liver and other cells and organs. Double-blind prospective clinical investigations to date suggest that Gln-enriched parenteral or enteral feedings are generally safe and effective in catabolic patients. Intravenous Gln (either as the L-amino acid or as Gln-dipeptides) has been shown to increase plasma Gln levels, exert protein anabolic effects, improve gut structure and/or function and reduce important indices of morbidity, including infection rates and length of hospital stay in selected patients subgroups. Additional blinded studies of Gln administration in catabolic patients and increasing clinical experience with Gln-enriched nutrient products will determine whether routine Gln supplementation should be given in nutrition support, and to whom. Taken together, the data obtained over the past decade or so of intensive research on Gln nutrition demonstrate that this amino acid is an important dietary nutrient and is probably conditionally essential in humans in certain catabolic conditions.

Effect of glutamine on leucine metabolism in humans

Hankard R.G.; Haymond M.W.; Darmaun D.
Ctr. de Recherche en Nutri. Humaine, Hopital Laennec, 44035 Nantes Cedex 1 France
American Journal of Physiology - Endocrinology and Metabolism (USA), 1996, 271/4 34-4 (E748-E754)

The aim of this study was to determine whether the putative protein anabolic effect of glutamine 1) is mediated by increased protein synthesis or decreased protein breakdown and 2) is specific to glutamine. Seven healthy adults were administered 5-h intravenous infusions of L-(1-14C)leucine in the postabsorptive state while receiving in a randomized order an enteral infusion of saline on one day or L-glutamine (800 micromol . kg-1 . h-1, equivalent to 0.11 g N/kg) on the other day. Seven additional subjects were studied using the same protocol except they received isonitrogenous infusion of glycine. The rates of leucine appearance (R(a Leu)), an index of protein degradation, leucine oxidation (Ox(Leu)), and nonoxidative leucine disposal (NOLD), an index of protein synthesis, were measured using the 14C specific activity of plasma alpha-ketoisocaproate and the excretion rate of 14CO2 in breath. During glutamine infusion, plasma glutamine concentration doubled (673 plus or minus 66 vs. 1,184 plus or minus 37 microM, P < 0.05), whereas R(a Leu) did not change (122 plus or minus 9 vs. 122 plus or minus 7 micromol . kg-1 . h-1), Ox(Leu) decreased (19 plus or minus 2 vs. 11 plus or minus 1 micromol kg-1 . h-1, P < 0.01), and NOLD increased (103 plus or minus 8 vs. 111 plus or minus 6 micromol . kg-1 . h-1, P < 0.01). During glycine infusion, plasma glycine increased 14-fold (268 plus or minus 62 vs. 3,806 plus or minus 546 microM, P < 0.01), but, in contrast to glutamine, R(a Leu) (124 plus or minus 6 vs. 110 plus or minus 4 micromol . kg- 1 . h-1, P = 0.02), Ox(Leu) (17 plus or minus 1 vs. 14 plus or minus 1 micromol . kg-1 . h- 1, P = 0.03), and NOLD (106 plus or minus 5 vs. 96 plus or minus 3 micromol . kg-1 . h-1, P < 0.65) all decreased. We conclude that glutamine enteral infusion may exert its protein anabolic effect by increasing protein synthesis, whereas an isonitrogenous amount of glycine merely decreases protein turnover with only a small anabolic effect resulting from a greater decrease in proteolysis than protein synthesis.

Nutritional support of the pediatric intensive care unit patient

Canete A.; Duggan C.
First Area/'La Paz' Children's Hosp., Madrid Spain
Current Opinion in Pediatrics (USA), 1996, 8/3 (248-255)

Nutritional support of the critically ill or postoperative pediatric patient continues to develop as a clinical science in the face of technologic, pharmacologic, and nutritional science advances. For ethical and logistical reasons, however, clinical trials of new technologies and interventions often are performed first in adult subjects, and the pediatric intensivist and nutritionist are thereby left to draw conclusions from this literature. This review summarizes recent developments in the clinical nutrition literature concerning the nutritional care of intensive care unit patients, emphasizing experience with pediatric patients when possible. The central role of estimating energy requirements in the intensive care unit, the development of enteral formulas with nutritional as well as possible immunologic properties, the use of anabolic hormones to attenuate the catabolic response to illness, the concept of 'conditionally essential' amine acids, and the propensity to use the parenteral route of nutrition when the enteral route is still available are discussed. Future directions in nutritional support, including the development of nutritional pharmacotherapy, are also considered.

Glutamine metabolism and transport in skeletal muscle and heart and their clinical relevance

Rennie M.J.; Ahmed A.; Khogali S.E.O.; Low S.Y.; Hundal H.S.; Taylor P.M.
Department of Anatomy and Physiology, University of Dundee, Dundee DD1 4HN United Kingdom
Journal of Nutrition (USA), 1996, 126/4 Suppl. (1142S-1149S)

The glutamine and glutamate transporters in skeletal muscle and heart appear to play a role in control of the steady-state concentration of amino acids in the intracellular space and, in the case of skeletal muscle at least, in the rate of loss of glutamine to the plasma and to other organs and tissues. This article reviews what is currently known about transporter characteristics and mechanisms in skeletal muscle and heart, the alterations in transport activity in pathophysiological conditions and the implications for anabolic processes and cardiac function of altering the availability of glutamine. The possibilities that glutamine pool size is part of an osmotic signaling mechanism to regulate whole body protein metabolism is discussed and evidence is shown from work on cultured muscle cells. The possible uses of glutamine in maintaining cardiac function perioperatively and in promoting glycogen metabolism are discussed.

Search for the competitive edge: a history of dietary fads and supplements.

Applegate EA; Grivetti LE
Department of Nutrition, University of California, Davis 95616, USA.
J Nutr (United States) May 1997, 127 (5 Suppl) p869S-873S

The premise and promise of ergogenic aid use is rooted in antiquity and is based upon superstition and ritualistic behavior of athletes who perceive that past performances were predicated upon unique dietary constituents or dietary manipulation. Accounts from ancient times recommended that athletes and soldiers preparing for battle consume specific animal parts to confer agility, speed or strength associated with that animal. Scientific understanding of the chemical and physiological nature of muscular work in the early 20th century was followed by ergogenic aid use by athletes and rationalized as "scientific" justification. Ergogenic aids such as alkaline salts, caffeine, carbohydrate and protein have been used by athletes with variable success. As nutritionists and exercise physiologists discovered and perfected the scientific understanding of metabolic reactions, athletes in turn experimented with the amount, form and timing of administration in the search for optimal performance. Anabolic steroids and blood doping enhance athletic performance, but health risks, ethics and sportsmanship contravene their use. Popularity and use of ergogenic aids often have preceded scientific substantiation of claims. Current products such as protein isolates and antioxidant nutrients commonly are used by athletes, and many ergogenic aids available today differ little from those used long ago.

The usefulness of dietary medium-chain triglycerides in body weight control: fact or fancy?

Bach AC; Ingenbleek Y; Frey A
CEPE, CNRS, Strasbourg, France.
J Lipid Res (United States) Apr 1996, 37 (4) p708-26

Compared to long-chain triglycerides (LCT), medium-chain triglycerides (MCT) display some specific physico-chemical, and biological characteristics. Thus, MCT are currently used in clinical nutrition as energy-yielding substrates, and have been advocated for three decades as a useful mean for body weight reduction. This review encompasses most aspects of MCT metabolism arguing this slimming hypothesis pro and con. Findings in support of the opinion (lower energy density, control of satiety, rapid intrahepatic delivery and oxidation rates, poor adipose tissue incorporation) may be invalidated by counteracting data (stimulation of insulin secretion and of anabolic-related processes, increased de novo fatty acid synthesis, induced hypertriglyceridemia). The balance between these two opposing influences depends on the composition (energy intake, nature of ingredients, MCT/LCT ratio, octanoate/decanoate ratio) and duration of the regimen. Due to the high energy level (around 50%) of MCT necessary to achieve body weight loss, long-term compliance to such slimming regimens is unlikely in human nutrition. (222 Refs.)

Nutritional status and lipid profiles of trained steroid-using bodybuilders.

Keith RE; Stone MH; Carson RE; Lefavi RG; Fleck SJ
Department of Nutrition and Food Science, Auburn University, Auburn, AL 36849, USA
Int J Sport Nutr (United States) Sep 1996, 6 (3) p247-54

Fourteen trained male anabolic steroid-using bodybuilders (SBBs) (19-41 years) were recruited for the study. Three-day diet records were obtained from SBBs and analyzed. A resting venous blood sample was drawn, and serum/plasma was subsequently analyzed for various nutritionally related factors. Results showed that mean dietary energy (4,469 +/- 1,406 kcal), protein 252 +/- 109 g), and vitamin and mineral intakes of SBBs greatly exceeded U.S. Recommended Dietary Allowances. Dietary cholesterol intake was 2.8 times the recommended levels. Mean serum/plasma nutrient concentrations of SBBs were within normal range. However, individual SBBs had a number of serum/plasma values outside of the normal or recommended range, the most notable of which was hypercalcemia, which was present in 42% of SBBs. Serum/plasma lipids were such as to increase the risk of cardiovascular disease in these subjects.

Ornithine alpha-ketoglutarate in nutritional support.

Cynober L
Laboratoire de Biochimie, Hopital Saint Antoine, Paris, France.
Nutrition (United States) Sep-Oct 1991, 7 (5) p313-22

Ornithine alpha-ketoglutarate (OKG) is a salt formed of two molecules of ornithine and one molecule of alpha-ketoglutarate. OKG has been successfully used by the enteral and parenteral route in burn, traumatized, and surgical patients and in chronically malnourished subjects. According to the metabolic situation, OKG treatment decreases muscle protein catabolism and/or increases synthesis. In addition, OKG promotes wound healing. The mechanism of action of OKG is not fully understood, but the secretion of anabolic hormones (insulin, human growth hormone) and the synthesis of metabolites (glutamine, polyamines, arginine, ketoacids) may be involved. (101 Refs.)

Anabolic effects of insulin-like growth factor-I (IGF-I) and an IGF-I variant in normal female rats.

Tomas FM, Knowles SE, Chandler CS, Francis GL, Owens PC, Ballard FJ
Cooperative Research Centre for Tissue Growth and Repair, Child Health Research Institute, Adelaide, South Australia.
J Endocrinol (England) Jun 1993, 137 (3) p413-21

Administration of IGF-I over a 14-day period to growing female rats via s.c. implanted osmotic pumps led to an increased body weight gain, an improved N retention and a greater food conversion efficiency. The effects were dose-dependent, with the highest daily dose tested, 278 micrograms/day, producing 18-26% increases in these measurements. LR3IGF-I, a variant of human IGF-I that contains an amino terminal extension peptide as well as glutamate-3 replaced by arginine and exhibits very weak binding to IGF-binding proteins, was substantially more potent than the natural growth factor, in the 44 micrograms/day of this peptide produced similar effects to the high IGF-I dose. Organ weight and carcass composition measurements showed that the two IGF peptides generally maintained body proportions at those existing when the experiment began. Muscle protein synthesis and myofibrillar protein breakdown were both slightly increased by IGF treatment, so that the observed improvement in N retention could not be explained through protein accretion rates calculated from these measures. Infusion of human GH at a dose of 213 micrograms/day did not stimulate body growth. This investigation establishes that IGF peptides stimulate the growth of normal growing animals, with IGF-I variants that bind less well to IGF-binding proteins being more active than IGF-I.

Arginine needs, physiological state and usual diets. A reevaluation.

Visek WJ
J Nutr 1986 Jan;116(1):36-46

Evidence is discussed that puts in question the widely held belief that adult mammals, including human beings, can meet all of their arginine needs by endogenous synthesis. Arginine, used in synthesis of body proteins, is essential for ammonia detoxification via urea synthesis, which prevents metabolic derangements caused by elevations in tissue ammonia. It is a precursor for polyamine synthesis and is the only source of amidino groups for the formation of creatine, a major source of high energy phosphate for regeneration of ATP in muscle. Arginine at supraphysiologic doses is thymotropic and a secretagogue for hormones that control growth and metabolism. Studies in mature rats show that glucose tolerance, the rate of repletion from severe protein undernutrition and recovery from trauma are significantly accelerated by dietary arginine. Oral or intravenous administration of excessive arginine reverses nitrogen loss and immune suppression after trauma in rats, and healthy human volunteers consuming 30 g of oral supplements or arginine have shown significantly enhanced immunoreactivity of the lymphocytes of their peripheral blood. Calculations based on creatinine excretion show that 0.8 g of protein/kg body weight of the quality supplied by the usual American diet barely provides sufficient arginine for synthesizing the quantity of creatinine excreted daily in the urine of 70-kg adults. Human patients who often consume less than this amount of protein show a decline in creatinine excretion during illness; the decrease suggests that their intake of arginine is less than optimal. Recent studies of intraspecies and interspecies differences in responses to arginine reemphasize that dispensability or indispensability of arginine is a matter of definition and that growth and nitrogen balance data impose significant limitations on the drawing of far-reaching conclusions about the needs for arginine by mammalian adults including humans. Orotic acid excretion, immune responsiveness and circulating hormone levels are measures that should be evaluated for identifying when enhancement of arginine intakes might prove beneficial.

Effects of dietary chromium picolinate supplementation on growth, carcass characteristics, and accretion rates of carcass tissues in growing-finishing swine.

Mooney KW; Cromwell GL
Department of Animal Sciences, University of Kentucky, Lexington 40546, USA.
J Anim Sci 1995 Nov;73(11):3351-7

An experiment was conducted to evaluate the effects of chromium picolinate (CrP) on growth performance, carcass composition, and tissue accretion rates in pigs from 27 to 109 kg BW. Seven littermate sets of Yorkshire-Hampshire barrows, individually penned, were fed a fortified, corn-soybean meal basal diet (.95% lysine from 27 to 55 kg; .80% lysine from 55 to 109 kg) supplemented with 0 or 200 micrograms/kg of Cr from CrP. Addition of CrP increased (P < .09) ADG but did not affect ADFI or feed:gain ratio. Average and 10th rib backfat and longissimus muscle area were not affected by Cr supplementation. The right side of the carcass was physically dissected into muscle, fat, bone, and skin. Additionally, five pigs were killed for determination of initial body composition. Dietary CrP addition increased (P < .02) the percentage of muscle and decreased (P < .06) the percentage of fat. Total gain of dissected bone and skin were not different between treatments, but CrP increased (P < .06) the total gain of dissected muscle and decreased (P < .02) the total gain of dissected fat. Also, CrP increased the daily accretion rates of muscle (P < .05) and bone (P < .03) and decreased the daily accretion rate of fat (P < .05). The left side of the carcass was ground for determination of water, protein, lipid, and ash. The addition of CrP to the diet increased the percentage (P < .09) and accretion rate (P < .09) of water and increased the percentage (P < .004), total gain (P < .02), and accretion rate (P < .02) of protein while decreasing (P < .04) the percentage of lipid. Pigs fed CrP also had a decreased (P < .004) percentage of lipid in the dissected carcass muscle. Water, protein, and ash from the dissected muscle were not different between treatments. These results suggest that CrP supplementation throughout the entire growing-finishing phase increases the total gain and accretion rate of muscle while decreasing the total gain and accretion rate of fat. This results in carcasses with an increased percentage of muscle and decreased percentage of fat.

Anabolic effects of insulin on bone suggest a role for chromium picolinate in preservation of bone density.

McCarty MF
Med Hypotheses (England) Sep 1995, 45 (3) p241-6

Activation of osteoclasts by parathyroid hormone (PTH) is mediated by PTH stimulation of osteoblasts, and is dependent on a PTH-induced rise in protein kinase C activity. Physiological levels of insulin reduce the ability of PTH to activate protein kinase C in osteoblasts, suggesting that insulin may be a physiological antagonist of bone resorption. In addition, insulin is known to promote collagen production by osteoblasts. These findings imply that efficient insulin activity may exert an anabolic effect on bone, and rationalize the many clinical studies demonstrating reduced bone density in Type I diabetes. Recently, the insulin-sensitizing nutrient chromium picolinate has been found to reduce urinary excretion of hydroxyproline and calcium in postmenopausal women, presumably indicative of a reduced rate of bone resorption. This nutrient also raised serum levels of dehydroepiandrosterone-sulfate, which may play a physiological role in the preservation of postmenopausal bone density. The impact of chromium picolinate (alone or in conjunction with calcium and other micronutrients) on bone metabolism and bone density, merits further evaluation in controlled studies. (69 Refs.)

Effect of chromium picolinate on growth, body composition, and tissue accretion in pigs.

Boleman SL; Boleman SJ; Bidner TD; Southern LL; Ward TL; Pontif JE; Pike MM
Department of Animal Science, Louisiana State University Agricultural Center, Baton Rouge 70803, USA.
J Anim Sci 1995 Jul;73(7):2033-42

An experiment was conducted to evaluate the effect of dietary chromium picolinate (CrP) on growth and body composition of pigs. Twenty-four barrows (three from each of eight litters) were randomly allotted within litter to one of three treatments: 1) basal (B) diet from 19.1 to 106.4 kg BW (Control); 2) B from 19.1 to 57.2 kg BW and then B + 200 ppb of chromium as CrP from 57.2 to 106.4 kg BW (CrP-F); and 3) B + 200 ppb of chromium as CrP from 19.1 to 106.4 kg BW (CrP- GF). Average daily gain and ADFI were reduced (P < .08) and first rib fat thickness was increased (P < .08) in pigs fed CrP-GF compared with pigs fed the Control diet. Specific gravity of the carcass was not affected (P > .10) by treatment. Tenth rib fat was reduced (P < .01) in pigs fed CrP-F compared with pigs fed CrP-GF, and percentage of muscle was increased in pigs fed CrP-F (P < .09) compared with pigs fed either the Control or CrP-GF diets. Leaf fat (P < .05) and lung weights (P < .08) were reduced in pigs fed CrP-F compared with pigs fed CrP-GF. As determined by physical-chemical separation, pigs fed CrP-GF had an increased (P < .07) percentage of intermuscular fat compared with pigs fed the Control or CrP-F diets. Pigs fed CrP-F had a lesser (P < .07) percentage of total fat and a greater (P < .07) percentage of muscle than pigs fed the Control or CrP-GF diets. As determined by mechanical-chemical separation, pigs fed CrP-F had a greater (P < .10) percentage of moisture than pigs fed the Control diet and a lesser (P < .10) percentage of fat and a greater (P < .06) percentage of ash than pigs fed the Control or CrP-GF diets. Pigs fed CrP-GF had an increased (P < .04) daily fat accretion compared with pigs fed CrP-F. Sensory and shear force values were not affected by CrP, with the exception that meat from pigs fed CrP-GF had a greater (P < .10) shear force value than meat from pigs fed CrP-F. These results suggest that dietary supplementation of CrP in the finishing phase of pig production may increase muscle and decrease fat deposition; however, not all measures of muscling or fatness were improved by CrP.

Longevity effect of chromium picolinate--'rejuvenation' of hypothalamic function?

McCarty MF
Nutrition 21, San Diego, California 92109.
Med Hypotheses (England) Oct 1994, 43 (4) p253-65

The first rodent longevity study with the insulin-sensitizing nutrient chromium picolinate has reported a dramatic increase in both median and maximal lifespan. Although the observed moderate reductions in serum glucose imply a decreased rate of tissue glycation reactions, it is unlikely that this alone can account for the substantial impact on lifespan; an effect on central neurohormonal regulation can reasonably be suspected. Recent studies highlight the physiological role of insulin as a modulator of brain function. I postulate that aging is associated with a reduction of effective insulin activity in the brain, and this contributes to age-related alterations of hypothalamic functions that result in an 'older' neurohormonal milieu; consistent with this possibility, diabetes leads to changes of hypothalamic regulation analogous to those seen in normal aging. Conversely, promoting brain insulin activity with chromium picolinate may help to maintain the hypothalamus in a more functionally youthful state; increased hypothalamic catecholamine activity, sensitization of insulin-responsive central mechanisms regulating appetite and thermogenesis, and perhaps trophic effects on brain neurons may play a role in this regard. Since both the pineal gland and thymus are dependent on insulin activity, chromium may aid their function as well. Thus, the longevity effect of chromium picolinate may depend primarily on delay or reversal of various age-related changes in the body's hormonal and neural milieu. A more general strategy of hypothalamic 'rejuvenation' is proposed for extending healthful lifespan.

Effects of chromium picolinate on beginning weight training students.

Hasten DL, Rome EP, Franks BD, Hegsted M
Dept. of Kinesiology, Louisiana State University, Baton Rouge 70803-7101.
Int J Sport Nutr (United States) Dec 1992, 2 (4) p343-50

Changes in body weight (BW), a sum of three body circumferences (sigma C), a sum of three skinfolds (sigma SF), and the one-repetition maximum (1RM) for the squat (SQ) and bench press (BP) were examined in 59 college-age students (37 males [M], 22 females [F]) over a 12-week weight lifting program. Using a double-blind protocol, half of the students were given 200 micrograms/day chromium (Cr) in the form of chromium picolinate (CrPic) while the other half received a placebo (P). Therefore four groups were randomly formed: F-CrPic (n = 12), F-P (n = 10), M-CrPic (n = 18), and M-P (n = 19). All groups had significant increases in sigma C and significant decreases in sigma SF. No treatment effects were seen for the strength measurements, although the males experienced greater absolute increases. The only significant treatment effect found was due to the F-CrPic group gaining more BW (p = 0.0048) than the other three groups. It was concluded that CrPic supplementation had a greater effect on the females than on the males.

Modulation of immune function and weight loss by L-arginine in obstructive jaundice in the rat.

Kennedy JA, Kirk SJ, McCrory DC, Halliday MI, Barclay GR, Rowlands BJ
Department of Surgery, Queen's University of Belfast, UK.
Br J Surg (England) Aug 1994, 81 (8) p1199-201

Jaundiced surgical patients have a high incidence of postoperative complications. Many causative factors have been identified including cachexia and immune suppression. The amino acid L-arginine has anabolic and immunostimulatory properties. It was hypothesized that dietary supplementation with L-arginine would diminish the weight loss and immune suppression of obstructive jaundice. Sixteen male Wistar rats rendered jaundiced by bile duct ligation were allocated to two groups. The test group (n = 8) received drinking water supplemented with 1.8 percent L-arginine ad libitum and the control group (n = 8) received a solution of isonitrogenous glycine. Both groups had free access to standard chow. Body-weight, and fluid and food intake were recorded. After 21 days, delayed-type hypersensitivity to 2,4-dinitrofluorobenzene was assessed. Animals receiving L-arginine consumed more food than controls (mean(s.e.m.) 414(16) versus 360(13) g, P < 0.05) and lost less weight (mean(s.e.m.) proportion of initial body-weight lost 7.8(1.2) versus 14.8(1.4) percent, P < 0.05). The delayed-type hypersensitivity response was significantly greater in rats receiving L-arginine (mean(s.e.m.) increase in ear thickness 23.9(2.7) versus 9.4(2.1) percent, P < 0.05). In this animal model of obstructive jaundice dietary supplementation with L-arginine diminished both weight loss and immune suppression.

Nutritional ergogenic aids: chromium, exercise, and muscle mass.

Clarkson PM
Department of Exercise Science, University of Massachusetts, Amherst 01003.
Int J Sport Nutr (United States) Sep 1991, 1 (3) p289-93

Athletes who want to develop muscle mass have sought various ways to reach this goal. We are all too familiar with the abuse of anabolic steroids and growth hormone. Given the concern for such abuses, athletes and coaches are seeking new and safer means to achieve the same end. Within the last couple of years, advertisements for chromium supplements have been prominently displayed in body-building and strength-training magazines. These supplements are purported to be a safe alternative to anabolic steroids and are said to promote an increase in muscle mass. This brief review will focus on the theoretical basis for believing that chromium supplements will increase muscle mass, and on the current research regarding the relationship of chromium and exercise.

Efficacy of chromium supplementation in athletes: emphasis on anabolism

Lefavi RG; Anderson RA; Keith RE; Wilson GD; McMillan JL; Stone MH
Health and Human Performance Laboratory, Georgia Southern University, Statesboro GA 30460.
Int J Sport Nutr (United States) Jun 1992, 2 (2) p111-22

As the biologically active component of glucose tolerance factor (GTF), the essential trace mineral chromium is now being marked to athletes. GTF potentiates insulin activity and is responsible for normal insulin function. Thus, insulin's effects on carbohydrate, fat, and protein metabolism are dependent upon the maintenance of adequate chromium stores. Due to excessive chromium loss and marginal chromium intake, athletes may have an increased requirement for chromium. Therefore, in some circumstances the dietary supplementation of a chromium compound may be efficacious. The restoration and maintenance of chromium stores via supplementation would promote optimal insulin efficiency, necessary for high-level athletic performance. However, potential anabolic effects of enhanced insulin function would likely be marginal, and reports of short-term anabolic increases from the supplementation of an organic chromium compound need to be confirmed. (87 Refs.)

Dietary supplements: Alternatives to anabolic steroids?

Cowart V.S.
Physician Sportsmed. (USA), 1992, 20/3 (189-193+196+198)

No abstract.

Direct anabolic effects of thyroid hormone on isolated mouse heart

Crie J.S.; Wakeland J.R.; Mayhew B.A.; Wildenthal K.
Department of Physiology, Pauline and Adolph Weinberger Laboratory for Cardiopulmonary Research, The University of Texas Health Science Center at Dallas, Dallas, TX 75235 USA
Am. J. Physiol. (USA), 1983, 14/3 (C328-C333)

a) The direct effects of L-and D-triiodothyronine (Tsub 3) on cardiac protein metabolism were investigated using fetal mouse hearts in organ culture. This model allowed the production of 'thyrotoxicosis' in isolated hearts in vitro in the absence of the usual systemic metabolic and hemodynamic effects of thyroid hormones. Hearts were studied during the first 24 h of Tsub 3 exposure in culture, before changes in beating rate due to Tsub 3 occurred. Phenylalanine release was decreased by 26 + or - 2.3% (P < 0.001) by the optimal concentrations of Tsub 3 (10sup -sup 7 to 10sup -sup 6 M). Changes were similar in the presence or absence of insulin. D-Tsub 3 was also anabolic, decreasing phenylalanine release by 24 or - 2.5% (P < 0.001) at concentrations of 10sup -sup 6 to 10sup -sup 5 M. The L-isomer increased protein synthesis by 23 + or - 6.8% (P < 0.05) and decreased protein degradation, as measured by phenylalanine release in the presence of cycloheximide, by 5 + or - 1.6% (P < 0.01). The D-isomer also increased protein synthesis but had no measurable effect on protein degradation. We conclude that thyroid hormones can exert direct anabolic effects on heart in the absence of systemic hemodynamic and metabolic changes. These effects are mediated primarily through an acceleration of the rate of protein synthesis; in the case of L-Tsub 3, a small inhibition of proteolysis may also occur.

Feeding conjugated linoleic acid to animals partially overcomes catabolic responses due to endotoxin injection.

Miller CC; Park Y; Pariza MW; Cook ME
Poultry Science Dept., U.W. Madison 53706.
Biochem Biophys Res Commun (United States) Feb 15 1994, 198 (3 p1107-12)

The ability of conjugated linoleic acid to prevent endotoxin-induced growth suppression was examined. Mice fed a basal diet or diet with 0.5% fish oil lost twice as much body weight after endotoxin injection than mice fed conjugated linoleic acid. By 72 hours post injection, mice fed conjugated linoleic acid had body weights similar to vehicle injected controls; however, body weights of basal and fish oil fed mice injected with endotoxin were reduced. Conjugated linoleic acid prevented anorexia from endotoxin injection. Splenocyte blastogenesis was increased by conjugated linoleic acid.