L-carnitine supplementation does not promote weight loss in ovariectomized rats despite endurance exercise.

In this five-week study, we tested the hypotheses that free access to a maintenance diet supplemented with L-carnitine (L-C) would reduce body fat in adult, sedentary, ovariectomized (OVX) rats, and that there would be an additive effect of L-C on weight reduction in swim-trained animals. As expected, serum carnitine was higher in rats fed the L-C diet, and the OVX-induced weight gain and abdominal fat were counteracted by swimming. L-C supplementation did not reduce the weight gain or abdominal fat in these adult female rats, Moreover, though not reaching statistical significance, rats that were fed L-C demonstrated a tendency for greater weight gain than their basal-fed counterparts despite no difference in energy intake. If the results of this study on ovariectomized rats can be translated to postmenopausal women, moderate intensity exercise may be recommended, but L-C supplementation, with no energy restriction, may be contraindicated as a weight loss method in this cohort.

Swim-trained rats have greater bone mass, density, strength, and dynamics.

Weight-bearing exercise is traditionally recommended for improving bone health in postmenopausal women. Effects of swim exercise were studied as an alternative to weight-bearing exercise in ovariectomized rats. Rats in a swim group (Sw, n = 8) swam for 12 wk, 5 days/wk for 60 min per session. A control group (Con, n = 9) engaged in no structured exercise. Femurs were analyzed for bone mineral density and for bone mineral content by dual energy X-ray absorptiometry, biomechanical properties by three-point bending (Instron), and bone structure and formation by histomorphometry. Food intake did not differ among groups. Final body weights were significantly lower in Sw compared with Con (P < 0.05). Swimmers had significantly greater femoral shaft bone mineral density and content (P < 0.05) compared with Con. Femurs of the Sw group had greater mechanical properties (P < 0.05) compared with Con. Histomorphometric data were significantly better in the Sw group compared with Con after the 12-wk intervention (P < 0.05). In conclusion, data from this study demonstrate some beneficial effects of swim exercise on bone structure, turnover, and strength.

Creatine supplementation alters the response to a graded cycle ergometer test.

To determine the effects of creatine supplementation on cardiorespiratory responses during a graded exercise test (GXT) 36 trained adults (20 male, 16 female; 21-27 years old) performed two maximal GXTs on a cycle ergometer. The first GXT was done in a nonsupplemented condition, and the second GXT was done following 7 days of ingesting either 5 g creatine monohydrate, encased in gelatin capsules, four times daily (CS, 13 male, 6 female), or the same number of glucose capsules (PL, 7 male, 10 female). CS significantly (P<0.05) improved total test time [pre-CS = 1217 (240) s, mean (std. dev.) versus post-CS = 1289 (215) s], while PL administration had no effect (P>0.05) on total test time [pre-PL= 1037 (181) s. versus post-PL= 1047 (172) s]. In addition, both oxygen consumption (VO2) and heart rate at the end of each of the first five GXT stages were significantly lower after CS, but were unchanged after PL. Moreover, the ventilatory threshold occurred at a significantly greater VO2 for CS [pre-CS = 2.2 (0.4) l x min(-1) or 66% of peak VO2 versus post-CS = 2.6 (0.5) l x min(-1) or 78% of peak Vo2; pre-PL = 2.6 (0.9) l x min(-1) or 70% peak VO2 versus post-PL = 2.6 (1.1) l x min(-1) or 68% of peak Vo2]. Neither CS nor PL had an effect on peak Vo2 [pre-CS = 3.4 (0.7) l x min(-1) versus post-CS = 3.3 (0.7) l x min(-1); pre-PL = 3.7 (1.1) l x min(-1) versus post-PL = 3.7 (1.1) l x min(-1)]. Apparently, CS can alter the contributions of the different metabolic systems during the initial stages of a GXT. Thus, the body is able to perform the sub-maximal workloads at a lower oxygen cost with a concomitant reduction in the work performed by the cardiovascular system.

Swimming eliminates the weight gain and abdominal fat associated with ovariectomy in the retired breeder rat despite high-fat diet selection.

The effects of swim-training on choice of dietary fat, carbohydrate or protein, weight gain, energy intake, and energy efficiency were examined in ovariectomized and sham-operated retired breeder rats. After a 3 week training period of increased duration, rats swam for 75 min per session (5 days per week) for 4 weeks. Ovariectomized rats gained more weight than sham rats, while swimming reduced weight gain and abdominal fat. As a percentage of total intake, macronutrient choices (weight and energy) were similar for all groups, ovariectomized animals consumed more food and more energy, compared with sham animals. All rats freely chose the majority of their food (g) as carbohydrate and the majority of energy (kJ) as fat. Results indicate that a moderate intensity training program of swimming prevented the weight gain following ovariectomy in older rats despite their excessive caloric intake of fat.

Ovariectomy fails to modify the cardiac myosin isoenzyme profile of adult rats.

Estrogen has been shown to help maintain the elevated expression of the high ATPase myosin isoform, V1, present in the hearts of young rats (< 70 days of age). Because hearts of this age are still undergoing significant maturation, the current study sought to determine if estrogen similarly regulates myosin isoenzyme expression in the mature adult heart. To make this determination, ten month old retired female Sprague-Dawley rats were made estrogen-deficient by ovariectomy (OVAR, n = 8). Sham-operated (CONTR, n = 8) animals served as controls. Nine weeks later, the animals were sacrificed and left ventricular tissue collected. Crude myofibrills were isolated from these samples and electrophoretically separated into the three isoenzymatic forms of cardiac myosin (V1, V2, and V3). OVAR animals were larger than the CONTR group (p < 0.05), but heart weight/body weight ratios were not different between groups. Distribution of myosin among its three isoenzymes was similar between groups (CONTR: V1, 80%, V2, 14%; V3, 6%; OVAR: V1, 77%, V2, 16%, V3, 7%). These data demonstrate that myosin isoenzyme distribution in the adult heart is unaltered by ovariectomy, suggesting that estrogen loses its ability to regulate expression of this protein in the mature heart.

Comparison of bone density measurement techniques: DXA and Archimedes' principle.

The standard method for determination of density (g/cm3) of bones from small animals has been the application of Archimedes' principle. A recent development has been software for the determination of "density" (g/cm2) of small animal bones with dual-energy X-ray absorptiometry (DXA). We compared Archimedes' principle and DXA (Hologic QDR-2000) in the measurement of the densities of whole and hollowed femurs of 5- to 6-month-old retired female breeder rats. In an attempt to ensure detectable treatment differences, rats were used from a low-vitamin D Holtzman and a supplemental-vitamin D Sprague-Dawley colony. Whole femur densities were higher for supplemental-vitamin D colony rats than for low vitamin D rats using both techniques (Archimedes' principle, p < 0.002; DXA, p < 0.005), and the densities from the two techniques were highly correlated (r = 0.82, p < 0.0001). Actual density values were higher for Archimedes' principle than for DXA. Other variables such as femur ash weight and calcium content were also highly correlated to densities with both techniques. Hollowed femur density values were higher than whole femur values with Archimedes' principle but lower with DXA. Colony effects for hollowed femur densities were diminished with Archimedes' principle (p < 0.03) and eliminated with DXA (p < 0.53). Investigation of whole bones is more biologically relevant, and both techniques were effective in detecting differences between whole femurs from low-vitamin D and supplemental-vitamin D colony rats.

Maternal consumption of a low vitamin D diet retards metabolic and contractile development in the neonatal rat heart.

During the fetal and suckling periods of mammalian development, the mother serves as the sole nutritional source for the offspring. As such, the quality of the maternal diet effects growth and development of the offspring during these periods. This study sought to determine if a maternal vitamin D deficiency altered the well characterized development of the neonatal heart. Weaned rat pups (21-day-old) were obtained from mothers who had consumed either a vitamin D-supplemented diet (3000 IU of vitamin D/kg) or a low vitamin D diet (< 200 IU of vitamin D/kg) prior to becoming pregnant and throughout pregnancy and suckling. These pups were sacrificed, hearts excised, and the hearts biochemically analysed for metabolic and contractile protein properties. The pups of dams fed the low vitamin D diet were slightly hypocalcemic relative to those on the supplemented diet (2.28 v 2.41 mumol/l, P < 0.05), had significantly lower body weights (43 v 55 g), heart weights (143 v 174 mg), citrate synthase activity (106 v 147 mumol g-1 min-1), and 3-hydroxyacyl CoA dehydrogenase activity (59 v 91 mumol g-1 min-1). Hexokinase activity (1.98 v 2.02 mumol g-1 min-1), and the distribution of cardiac myosin among its three isoforms (> 85% V1), were unaffected by this dietary deficiency, however myofibrillar protein content was approximately 15% lower in the experimental hearts. These data demonstrate that maternal consumption of a low vitamin D diet results in a general but significant slowing of neonatal cardiac development.

Effects of dietary boron in rats fed a vitamin D-deficient diet.

Although boron has long been known to be a required nutrient for plants, it was not until recently that there was any suggestion of a nutritional requirement for animals and humans. Addition of boron to the diet of vitamin D-deficient chicks indicated that boron may play a role in animal nutrition. Studies with rats have demonstrated that supplemental dietary boron has most marked effects when the diet is deficient in known nutrients. We observed higher apparent-balance values of calcium, magnesium, and phosphorus for rats fed a vitamin D-deprived diet with dietary supplemental boron (2.72 ppm), than for rats fed the same diet without added boron (0.16 ppm). The treatment group with dietary supplemental boron demonstrated a high degree of variability in response to boron. We hypothesize that relatively large and variable vitamin D stores in weanling rats from a colony supplemented with 3000 IU vitamin D/kg diet accounted for the observed variable response. A recent, unpublished study using weanling rats from a low-vitamin D colony appears to support this hypothesis.

Effects of chromium picolinate on beginning weight training students.

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.

Interactions of vitamin D with sodium zeolite A in rats from low and adequate vitamin D colonies.

Weanling rats (21 days old) from either a low vitamin D colony or an adequate vitamin D colony fed either a vitamin D adequate or a vitamin D deprived AIN-76A purified diet were used as a model to investigate interactions of vitamin D status with dietary sodium zeolite A (100 mg/kg body wt/day). Rats with adequate or replete vitamin D status had greater overall body weight gain, dry tibia weights and femur densities and ash weights than rats fed a vitamin D deprived diet. Addition of sodium zeolite A to the diets did not have an effect on plasma calcium, body weight gain or on femur density, ash and percent ash. Dietary sodium zeolite A increased total tibia fat in rats fed the vitamin D adequate diet and decreased total tibia fat in rats fed the vitamin D deprived diet. This effect of sodium zeolite A appeared to be beneficial to bone status in the groups fed adequate vitamin D, since these treatment groups had higher, although not significant, dry tibia weights with and without fat.

Suboptimal levels of dietary copper vary immunoresponsiveness in rats.

The effects of severe, moderate, and mild copper deficiencies on cellular and humoral immunity were studied. Fifty male Sprague-Dawley rats, 5 wk of age, were fed diets containing 0.5, 2.0, 3.5, or 5.0 micrograms Cu/g for either 4 or 8 wk. Ten of the rats were fed the control diet, but were pair-fed with the 0.5-micrograms/g treatment group. All rats were immunized once with sheep red blood cells. Mean plasma-copper concentration reflected the dietary levels of copper, and ceruloplasmin activity correlated highly to plasma copper. Rats consuming suboptimal levels of copper responded differently to the deficiencies, so copper status varied among those animals. After 8 wk, cell proliferation, when stimulated by phytohemagglutinin, was dependent on the copper status of the animal. Severely deficient rats had consistently lower lymphocyte stimulation indexes for phytohemagglutinin and concanavalin A, but specific antibody response was not reduced. Immunoglobulin G (IgG) concentrations were variable for all rats, and immunoglobulin M (IgM) concentrations were lower for the severely deficient rats. Suboptimal dietary copper may alter immune function in rats, depending on the ensuing effect on copper status.

Effect of boron on vitamin D deficient rats.

The effects of different levels of dietary boron were determined in vitamin D deficient rats. Vitamin D deficient diets containing either 0.158 ppm or 2.72 ppm of boron were fed to rats for 11 w, and calcium, magnesium, and phosphorus apparent absorption and balance were measured in the twelfth week. Higher apparent absorption and balance values for calcium and phosphorus were observed in the rats with higher dietary boron, but very few differences were seen in body wt, organ wt, and bone parameters. Balance measurements represented the present status of the rats after 12 w on the diets, but other measurements represented an accumulation over the lifetime of the rat, including a suckling period with ample vitamin D and boron. The data demonstrated that when rats are vitamin D deficient, as indicated by hypocalcemia, the level of boron in the diet affects mineral balance.

Recovery of rats from vitamin D-deficient mothers.

Two separate studies were conducted using weanling rats from either an unsupplemented, low vitamin D colony or a supplemented, adequate vitamin D colony. Severe hypocalcemia, slower increases in body weight gain, and lower apparent calcium, magnesium, and phosphorus balance values occurred in the rats from the low vitamin D colony fed a purified AIN-76A, vitamin D-devoid diet compared to rats from the vitamin D-adequate colony fed the same diet. Apparent calcium, magnesium, and phosphorus balance values, as well as most other measurements, in rats from the low vitamin D colony fed a purified AIN-76a, vitamin D-adequate diet were greater than or equal to those of rats never subjected to low vitamin D. This was suggestive of overcompensation in recovery from low maternal vitamin D. However, rats from the low vitamin D colony fed an unrefined (chow), vitamin D-adequate diet had lower apparent balance and bone values compared with rats from the vitamin D-supplemented colony fed the same diet. Presumably high levels of calcium, magnesium, and phosphorous in the unrefined diet prevented any overcompensation during recovery, as occurred with purified diets, from the earlier vitamin D deficiency. Overall, results indicated weanling rats from a low vitamin D colony had low vitamin D stores and were marginally vitamin D-deficient. In addition, recovery from the marginal deficiency had occurred to a large extent after feeding a purified, vitamin D-adequate diet. The results suggest the use of low vitamin D colony rats as a model for human, marginal vitamin D deficiency.

Anthropometric measurements of white and black southern adolescent girls.

Anthropometric measurements of 691 white and 550 black 12-, 14-, and 16-year-old girls from three income groups, residing in the southern United States, were evaluated, Heights, weights, mid-upper arm circumferences, and arm muscle areas of 14-year-old girls were significantly higher than those of 12-year-old girls and significantly lower than those of girls 16 years of age; triceps skinfolds, arm fat areas, and body mass indexes of 12-year-olds were significantly lower than those of older subjects. Blacks had significantly higher weights, body mass indexes, and arm muscle areas than whites. Black 12-year-old girls were significantly taller than white 12-year-old girls but significantly shorter than older girls of either race; white 16-year-old girls were significantly taller than blacks of that age. Body mass indexes of black 12-year-olds and white 14-year-olds were significantly higher than those of white 12-year-olds, and significantly lower than those of black 14- and 16-year-olds. Medium-income blacks and whites of all income levels had lower (usually significantly) weights, body mass indexes, mid-upper arm circumferences, arm muscle areas, and arm fat areas than low- and high-income blacks did. Anthropometric values of white, but not of black, girls were generally similar to those reported in surveys of primarily white girls.

A non-human primate model for the study of oral iron chelators.

Recent studies have demonstrated that parenteral deferroxamine can prolong life in patients with iron overload. We have developed a non-human primate model of iron overload and have accurately determined negative iron balance in parenteral and oral studies of deferroxamine and a new chelator, desferrithiocin. Cebus monkeys were loaded with iron dextran (10 mg/kg twice weekly) until their serum contained a transferrin saturation greater than 75%, and (in two animals) liver biopsies showed iron loading. When complete iron balance studies were performed at this time, basal iron balance was -53 +/- 11 micrograms (N = 4), providing a low background for provocative studies. Iron balance was determined for intramuscular (N = 2) and oral (N = 3) deferroxamine, as well as intramuscular (N = 1) and oral (N = 4) desferrithiocin. The pattern of iron excretion after parenteral deferroxamine strongly resembled that of the iron-loaded, transfused human. Desferrithiocin was found to have significant activity as an oral chelator. This Cebus monkey model accurately determines negative iron balance and readily permits precise comparison of iron chelators given parenterally or orally. This model may offer an important step between rodent and human trials of promising new iron chelators.

The effect of bulimia upon diet, body fat, bone density, and blood components.

A study was conducted to determine baseline data for dietary intake, percent body fat, bone mineral density, and blood components in women with bulimia. Eight bulimic and 10 control subjects completed the study. Each subject was assessed for a 3-day diet, frequency of purge, menstrual history, percent body fat, bone mineral density, by dual photon absorptiometry, and blood components. Mean age, height, and weight of subjects were similar. Percent body fat was similar for both groups. Vomiting was the predominant method of purge. Folacin intake was found to be significantly (p less than .05) lower in bulimic subjects. Control subjects consumed greater quantities of vitamin/mineral supplements than the bulimic subjects. Bone mineral density (gm/cm2) was found to be lower in bulimic subjects. Mean hemoglobin (gm/L [gm/dL]) levels were found to be significantly (p less than .01) higher in control subject. The data indicate that the method and duration of purge behavior could influence bone mineral density and blood components.

Actual and perceived nutritional knowledge of elderly individuals.

The perceived and actual nutritional knowledge of 150 noninstitutionalized elderly individuals was measured using mean scores on a 20 item test. Over 90% of those surveyed knew about the daily dietary need for vitamin C; about the life-long need for calcium; and about sources of fiber coming from whole grain breads and cereals. The elderly who thought they had fair knowledge of nutrition, in fact, did have higher mean scores on the nutritional knowledge test. Data analysis indicated that mean scores on actual nutritional knowledge were higher for those who were white and for those who were in a higher socioeconomic level. Mean scores of elderly men and women were found to be similar.

Factors related to blood pressure in a biracial adolescent female population.

Blood pressure levels, anthropometric parameters, and dietary intakes were assessed in 1981 and 1983 in a population of black (n = 236) and white (n = 296) adolescent girls, aged 14 and 16 years in 1983. The 14-year-old black girls exhibited significantly higher mean systolic and diastolic blood pressures than whites in both years. Body weight and Quetelet index were more strongly associated with blood pressure than were height and triceps skinfold thickness. Correcting blood pressures for weight, Quetelet index, 2-year changes in height, and age at menarche decreased in each case (but did not negate) the observed race differences in blood pressure. Dietary calcium and potassium intakes were inversely related to blood pressure, and a race difference in the intake of these nutrients (whites greater than blacks) was observed. Covariate adjustment for calcium, but not for potassium, decreased the magnitude of race differences in blood pressure. Family type (single-parent vs nuclear) and place of residence (urban vs nonurban) appeared to be the most important confounding variables for race differences in blood pressure, since differences largely were eliminated by controlling for these factors. Conflicting reports in the literature regarding the age range during which race differences in blood pressure become apparent may be partially attributed to the complex interrelationships among these factors and the potential influence of other genetic-environmental interactions that may also play a role in blood pressure regulation.

Evaluation of zinc and copper nutritional status and effects upon growth of southern adolescent females.

A biracial sample of twenty-nine 14-yr old and thirty 16-yr old females was evaluated for zinc and copper nutritional status. Socioeconomic, demographic, anthropometric and 24-h dietary recall data were collected and plasma zinc and copper and erythrocyte zinc levels determined. Mean plasma zinc was 83 +/- 15 micrograms/dl; racial differences were significant (p less than 0.05) with plasma zinc levels at 87 +/- 3 micrograms/dl for whites and 79 +/- 3 micrograms/dl for blacks. Mean plasma copper was 119 +/- 24 micrograms/dl and was slightly higher for blacks than for whites. Mean erythrocyte zinc was 8.3 +/- 2.7 micrograms/g and represented 10 times the level of zinc in plasma. Plasma copper levels were positively (p less than 0.05) related to body size. Plasma copper was negatively (p less than 0.05) related to dietary fiber. Other dietary and economic factors did not affect mineral status.