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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.
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