Relationship of thoracic kyphosis and lumbar lordosis to bone mineral density in women.

UNLABELLED: The relationship between spinal curvature and bone mineral density (BMD) in women was examined. Significant relationships were observed between spinal curvature and BMD in both pre- and postmenopausal women. Excessive spinal curvature may be associated with low bone mass in premenopausal women. INTRODUCTION: The purpose of this study was to examine the associations between spinal measurements of thoracic and lumbar curvatures and bone mineral density in pre- and postmenopausal women. METHODS: The data for this study were obtained from the Texas Woman's University Pioneer Project. Female participants (n = 242; premenopausal n = 104, postmenopausal n = 138) between the ages of 18 and 60 years were evaluated on multiple health measures. Thoracic and lumbar curvatures were measured with a 24-in. (60 cm) flexicurve. Bone mineral density was assessed via dual-energy X-ray absorptiometry (Lunar DPX IQ, version 4.6e). Pearson correlations and logistic regression analysis were used to examine the associations between the obtained spinal curvature measurements and bone mineral density. Significance was set at p < .05. RESULTS: Significant correlations were observed for the femoral neck and lumbar spine bone mineral density with thoracic and lumbar curve in premenopausal women (r = -.344 to - .525; p < .001). Slightly weaker, but significant, correlations were observed for femoral neck and lumbar spine in relation to thoracic and lumbar curve in postmenopausal women (r = -.288 to -.397; p < .01). Premenopausal women with thoracic curvature greater than 4 cm had a greater risk of having low bone mass compared to premenopausal women with less than 4 cm of curvature (odds ratio = 3.982, 95 % CI = 1.206, 13.144). CONCLUSIONS: The observed negative relationship suggests that as either thoracic or lumbar curvature increases, the regional bone mineral density decreases in both pre- and postmenopausal women.

Impact of detraining on bone loss in former collegiate female gymnasts.

Undesirable changes in health-related parameters are thought to occur in retiring female athletes, but this has not been examined in longitudinal studies. The purpose of this study was to examine longitudinal changes in bone mineral density (BMD), body composition, and dietary intake in gymnasts and controls. Nonathletic, college-age women (: n = 9) were selected as a control group for comparison to the gymnasts (n = 10). Initial BMDs for the gymnasts were determined by using dual energy X-ray absorptiometry (Lunar, DPX) at the beginning of their final competitive year. Initial BMDs for the controls were measured during a similar time-frame. Follow-up measurements were made at least 1-year after the initial measurement. Gymnasts had significantly greater BMD of the femoral neck (1.262 versus 1.058 g/cm2, respectively), Ward's triangle (1.230 versus 1.008 g/cm2), greater trochanter (1002 versus 0.822 g/cm2), and total body (1.232 versus 1.145 g/cm2) than controls while still competing (P < .05). Following retirement from competition, (mean years of retirement, 4 years), BMD of the gymnasts remained significantly greater than controls at total body, femoral neck, trochanter, and Ward's triangle (P < .05). Significant declines in femoral neck, Ward's triangle, and greater trochanter BMD were found in both gymnasts and controls (0.72% to 1.9% per year), but only gymnasts had a significant decline at the lumbar spine (0.87% per year). In conclusion, BMD changes in former gymnasts appear to be site-specific, and gymnasts continue to have greater proximal femur BMD than controls, despite their decreased exercise, which may help postpone or prevent osteoporosis later in life.

Creatine supplementation increases renal disease progression in Han:SPRD-cy rats.

The growing use of creatine as a potential ergogenic aid among active individuals has raised concern regarding its effects on the kidney, particularly among those individuals with compromised renal function. The object of this study is to investigate the effects of oral creatine supplementation in an accepted animal model of renal cystic disease. Han:Sprague-Dawley (SPRD)-cy rats with cystic kidney disease were administered a creatine supplement at a loading dose of 2.0 g/kg of diet for 1 week, followed by 5 weeks during which the dose was one fifth this amount, mimicking typical human consumption on a body-weight basis. Cystic kidney disease progression was assessed by measuring kidney size and fluid content and determining cyst scores. Renal function was assessed by measuring serum urea and creatinine concentrations and creatinine clearance. Creatine supplementation resulted in greater cyst growth and worsened renal function in the Han:SPRD-cy rat, evidenced by greater kidney weights (2.87 +/- 0.08 versus 2.61 +/- 0.09 g/100 g of body weight; P: = 0.0365), renal fluid contents (89.22 +/- 0.41 versus 87.38 +/- 0.48 g/100 g of kidney weight; P: = 0.0057), cyst scores (0.49 +/- 0.02 versus 0.40 +/- 0.03; P: = 0.0167) and serum urea concentrations (23.96 +/- 0.92 versus 20.65 +/- 1.06 mmol/L; P: = 0.0230), and lower creatinine clearances (0.125 +/- 0.098 versus 0.162 +/- 0.011 mL/min/100 g of body weight; P: = 0.0159). These results indicate that creatine supplements may exacerbate disease progression in an animal model of cystic renal disease. Although systematic research of the effects of creatine supplementation in humans with compromised renal function is awaited, it follows that creatine should be used with particular caution in individuals with or at risk for renal disease.

Safety of chronic exercise in a rat model of kidney disease.

PURPOSE: The objective of this study was to determine the effect of treadmill running on polycystic kidney disease (PKD) progression and bone mineral density in Han:SPRD-cy rats, an animal model of PKD. METHODS: Using a 2 x 2 design, normal and polycystic male rats were divided randomly into exercise and sedentary groups at 4 wk of age. The exercising group performed treadmill exercise (14 m x min(-1)) for 30 min 3 d x wk(-1) for 6 wk, whereas the control group remained sedentary. This 6-wk period represents the period of greatest cyst growth in this model. RESULTS: Both exercised and sedentary polycystic animals had significantly greater kidney weights, as well as greater concentrations of serum urea nitrogen and serum creatinine than control animals. Exercise did not alter these parameters in either normal or polycystic animals. In addition, bone mineral density and bone mineral content, determined by dual-energy x-ray absorptiometry, were not altered by exercise in these animals. Bone mineral content, however, was marginally lower in polycystic animals. CONCLUSIONS: These results support the safety of moderate exercise in PKD. Additional research in this area is needed since there may be other benefits that are derived from exercise in this population.

Lumbar bone mineral density in adolescent female runners.

BACKGROUND: The purpose of this study was to determine if there were significant differences in lumbar bone mineral density (L2-L4, g/cm2) or several hormones among 3 groups of adolescent females: 10 amenorrheic runners, 10 eumenorrheic runners, and 10 eumenorrheic controls. EXPERIMENTAL DESIGN: comparative. SETTING: Cooper Clinic, Aerobics Center, Dallas, Texas. PATIENTS OR PARTICIPANTS: The subjects were white, non-smokers, aged 15.1-18.8 years, who were not taking birth control pills. All amenorrheic runners had less than 5 menstrual period in the past year, averaging 2,4 periods. The runners averaged approximately 36 miles/week (58.1 km) during the last 9 months of their training season and had been running for 1-5 years. INTERVENTIONS: None. MEASURES: Lumbar bone mineral density (BMD), 10 hormones, percentage of body fat, and dietary intake were measured. RESULTS: Mean lumbar BMD (g/cm2) did not differ significantly among groups (amenorrheic runners = 1.134, eumenorrheic runners = 1.165, controls = 1.148). However, expected trends were observed. Compared to the controls, the amenorrheic runners tended to have lower lumbar BMD and the eumenorrheic runners, higher. Although there were significant differences in concentrations of five serum hormones measured, all mean hormonal values were within normal ranges. Calcium intakes were low for all groups. CONCLUSIONS: In this study, with its small number of subjects and great variability within each group, it was concluded that there is no significant difference among amenorrheic runners, eumenorrheic runners, and controls in lumbar BMD. However, a longer period of amenorrhea might result in significantly lower BMD for the amenorrheic runners.

Bone mineral density and dietary intake in patients with Crohn's disease.

Individuals diagnosed with Crohn's disease are at an increased risk for developing low bone density. The exact cause of low bone mineral density in Crohn's disease patients has not been determined. The purpose of this study was to assess the incidence of low bone mineral density in premenopausal women with Crohn's disease and to determine the role diet plays in bone mineral density for this population. Bone mineral density of the lumbar spine (L2-L4), proximal femur, and forearm was measured in 51 female controls and 50 females with Crohn's disease using dual energy X-ray absorptiometry (Lunar DPXPlus, Madison, WI). Dietary intake for all Crohn's disease participants was analyzed using both 3-d dietary records and a food frequency questionnaire. When compared to healthy controls, bone mineral density values of Crohn's disease participants were decreased for all sites, particularly the spine (1.169 +/- 0.114, p = 0.054), Ward's area (0.831 +/- 0.128, p = 0.052), and the femoral neck (0.927 +/- 0.100, p = 0.01). Factors associated with lower bone density in Crohn's participants were weight, corticosteroid usage, length and age of diagnosis, history and length of resection, and dietary intakes of magnesium, copper, magnesium, vitamin K, and zinc. The results of this study indicate for the first time that diet plays a role in the development of low bone density in premenopausal women with Crohn's disease.

The effects of gymnastics training on bone mineral density.

The purpose of this study was to examine the effect of 27 wk of gymnastics training on bone mineral density (BMD), body composition, insulin-like growth factor I (IGF-I), and osteocalcin. Subjects were 11 female intercollegiate gymnasts and 11 controls. Dual energy x-ray absorptiometry (Lunar DPX) was used to determine BMD (L2-L4 and femur) and to assess body composition. The gymnasts were significantly lower in weight (53.9 and 60.8 kg) and % body fat (22.6 and 30.6) compared with controls. After training, body weights of gymnasts remained the same but there was a significant increase in lean tissue mass of 2.9 kg (6.7%, P < 0.05). No changes in body composition were observed in the controls. The gymnasts had significantly higher mean lumbar (1.321 vs 1.225), and femoral neck (1.163 vs 1.079) BMD (g.cm-2) than the controls. Lumbar BMD increased significantly (1.3%) in gymnasts following training but femoral neck BMD did not increase. No BMD changes occurred in the control group. Regarding serum IGF-I, no differences were seen between the groups or across time. Serum osteocalcin values were significantly higher in the gymnasts than the controls, but no differences were found across time. In conclusion, gymnasts had significantly higher BMDs than controls, and a significant increase in lumbar BMD was seen in the gymnasts following 27 wk of training.

Effect of indomethacin, epinephrine, prostaglandin E2 and insulin on lipolysis in bovine adipose tissue in vitro.

1. Fasting of ad libitum- or maintenance-fed steers for 4 to 9 days did not alter basal lipolytic rates in vitro. 2. Epinephrine stimulation of adipose tissue of fasted steers resulted in greater (P less than 0.05) lipolysis than in tissue from fed steers. 3. Prostaglandin E2 (PGE2) did not alter epinephrine-stimulated lipolysis in ad libitum- or maintenance-fed cattle. 4. Indomethacin did not influence basal lipolysis, even in the presence of PGE2. 5. Insulin neither affected basal lipolysis nor inhibited dibutyl cAMP-stimulated lipolysis.

Effect of dietary protein on cholesterol homeostasis in diabetic rats.

Normal and streptozotocin (STZ)-diabetic rats were studied in order to examine the effects of altering the type of dietary protein on cholesterol homeostasis. Rats were fed a non-purified or a purified diet containing either casein or soybean protein. The results obtained on the specific aspects of lipid metabolism were remarkably similar in control rats fed the non-purified (Purina Lab Chow) diet or the purified diet with the soybean protein. However, most of the findings obtained with the above two groups were different from those obtained with rats fed the purified diet containing casein. In the latter group, plasma cholesterol was elevated following a 15-day feeding period as compared to the other two dietary groups. The excess plasma cholesterol in the casein-fed group was found in two lipoprotein fractions with densities of 1.023-1.045 g/ml and 1.045-1.086 g/ml, respectively. The latter lipoprotein fraction was also enriched with apolipoprotein E. The casein-fed animals also showed a lower fractional rate of plasma cholesterol esterification and an abnormal accumulation of cholesterol in the body despite inhibition of cholesterol synthesis in the liver and in the intestines. Twelve to 15 days after the induction of diabetes, plasma cholesterol increased to a similar extent in the rats on all three diets. However, the distribution of cholesterol among the lipoprotein fractions was markedly different. The percentage of cholesterol in fractions of d less than 1.086 g/ml was increased while that carried in the fraction of d 1.086-1.161 g/ml decreased in the rats fed the nonpurified diet and the casein diet. In contrast, there was no change in the distribution of lipoprotein cholesterol between the diabetic and the control rats fed the soybean protein diet. The hepatic synthesis of cholesterol was unaltered in diabetic rats fed the nonpurified diet and the purified diet with soybean protein, but was increased 2.4-fold in diabetic rats fed casein. Intestinal cholesterol synthesis was increased in all three dietary groups. The increase was highest in the rats fed casein and lowest in rats fed soybean protein. The rate of sterol synthesis in the kidneys was not significantly affected by the diet or diabetes. In all three dietary groups diabetes led to an abnormal accumulation of cholesterol in the body. This accumulation was highest in the casein-fed rats and lowest in those fed the soybean protein diet. The cholesterol content of the kidneys was markedly increased by dietary casein.(ABSTRACT TRUNCATED AT 400 WORDS)

Evaluation of prostaglandin E2 as a regulator of lipolysis in bovine adipose tissue.

Effects of exogenous prostaglandin E2 (PGE2) on rates of lipolysis in sections of subcutaneous adipose tissue biopsied from fed and fasted Holstein steers were determined. The interaction of PGE2 with several exogenous effectors of lipolysis and of the adenylate cyclase-cAMP system also was measured. Epinephrine increased basal (nonstimulated) lipolysis approximately one-fold. Prostaglandin E2 had no effect on either basal or epinephrine-stimulated lipolysis. Dibutyryl cAMP increased rate of lipolysis .4-fold, whereas theophylline increased lipolysis more than one-fold. Theophylline had an additive effect on epinephrine-stimulated lipolysis. Dibutyryl cAMP increased theophylline-stimulated lipolysis but not epinephrine-stimulated lipolysis. Prostaglandin E2 had no effect on epinephrine-, dibutyryl cAMP- or theophylline-stimulated lipolysis. Fasting decreased basal lipolysis by 40%. Furthermore, lipolysis in tissue incubated with PGE2, epinephrine or PGE2 plus epinephrine decreased from 30 to 50% upon fasting. As also shown with tissue from fed steers, PGE2 did not alter basal or epinephrine-stimulated lipolysis in tissue from fasted steers. Influences of exogenous effectors on lipolysis in adipose tissue from fed and fasted steers indicate that PGE2 does not control the adenylate cyclase-cAMP system that regulates lipolysis in bovine adipose tissue.

Effect of fasting on free fatty acid, glycerol and cholesterol concentrations in blood plasma and lipoprotein lipase activity in adipose tissue of cattle.

Contributing factors in the regulation of triglyceride deposition in and fatty acid release from bovine adipose tissue were investigated. Six Holstein steers were fasted for 9 days and then refed for 41 days. Blood samples from the jugular vein and adipose tissue samples from backfat biopsies were taken during fasting and refeeding periods. Concentrations of plasma free fatty aids, glycerol and cholesterol and activity of lipoprotein lipase in adipose tissue from fasted and refed steers were measured. Plasma free fatty acid concentration increased almost eightfold during fasting. After 4 days of refeeding, free fatty acids in plasma had returned to basal concentration. Fasting had no effect on plasma cholesterol concentration; during refeeding, concentration decreased slightly and then returned to the basal concentration. Lipoprotein lipase activity decreased to 37% of the basal concentration during fasting and increased to 100% above prefasting values during refeeding. Significant changes in plasma free fatty acid and glycerol concentrations and in activity of lipoprotein lipase in adipose tissue during fasting and refeeding suggest that fatty acid mobilization and triglyceride uptake by adipose tissue of cattle adapt to great changes in energy intake. Correlations of measured blood metabolites in fasted and refed steers demonstrate that changes in rates of lipolysis and of triglyceride uptake by adipose tissue vary in a reciprocal manner.

Conversion of alanine, aspartate and lactate to glucose and CO2 in liver from stress-susceptible and stress-resistant pigs.

Rates of conversion of lactate, alanine and aspartate to glucose and oxidation of each to CO2 were determined in incubated liver slices from nine stress-susceptible (SS) and seven stress-resistant (SR) Yorkshire pigs ranging in body weight from 24 to 54 kg. Pigs were screened for stress susceptibility by exposure to halothane at 7 weeks of age. Stress was minimized before slaughter, and liver samples were obtained immediately after death. Rates of lactate and aspartate conversion to glucose were not significantly different between pig types. Mean rates of lactate conversion to glucose in livers of SS and SR pigs were 637 and 413 nmoles/(100 mg X 2 hours), respectively. Mean rates of aspartate conversion to glucose were 441 and 540 nmoles/(100 mg X 2 hours) in SS and SR pigs, respectively. Alanine conversion to glucose in livers of SS pigs was slower than that in SR pigs [527 and 813 nmoles/(100 mg X 2 hours), respectively]. Rates of hepatic gluconeogenesis from lactate probably do not predispose SS pigs to the lactic acidosis observed during the porcine stress syndrome. Rates of lactate, alanine and aspartate oxidation to CO2 in livers of SS pigs were 61, 59 and 76%, respectively, of the rates observed in SR pigs. Decreased rates of substrate oxidation to CO2 may contribute to the development of the syndrome in SS pigs.

Gluconeogenesis from lactate in liver of stress-susceptible and stress-resistant pigs.

In vitro rates of lactate conversion to glucose and oxidation to CO2 were determined in livers of stress-susceptible (SS) and stress-resistant (SR) pigs because we hypothesized that livers of SS pigs had a lower capacity than livers of SR pigs to remove lactate from blood. Stress-susceptibility was determined by reaction to halothane at 7 weeks of age. At approximately 9 weeks of age, pigs were assigned to one of three experimental diets. Pigs weighing 95 kg were slaughtered immediately after stress, and liver samples were obtained. Incorporation of lactate into glucose in liver of SS pigs was 38% of that in SR pigs. Addition of either vitamin C or vitamins C and E plus magnesium oxide and collagen extract to a corn-soy diet did not alter lactate conversion to glucose, but depressed lactate oxidation to CO2. No differences were detected in either activities of lactate dehydrogenase, HAD-malate dehydrogenase, phosphoenolpyruvate carboxykinase, fructose-1,6-diphosphatase, and glucose-6-phosphatase or concentration of glycogen in livers of SS and SR pigs. Our data indicate that livers of SS pigs possess a lower capacity to incorporate lactate into glucose and to oxidize lactate to CO2; maximal activities of enzymes measured in this study are not the cause of these differences. Reduced capacity of lactate metabolism in livers of SS pigs seems a part of the etiology of the porcine stress syndrome.