Coronary circulation and metabolic function in endurance trained paraplegics

OBJECTIVE: To determine the effect of physical activity on pulmonary, cardiovascular and metabolic activity in paraplegics. PATIENTS AND METHODS: Eight male paraplegics (average age 35.7 [range 25-47] years) had been selected from a pool of training members of the German Sport Union for the Disabled. They performed graded arm crank training for 8.3 +/- 3.1 h/week. Left ventricular volume (LVV), stroke volume (SV), wall thickness (WT), heart rate (HR) as well as serum lactate concentration were measured after different levels of the graded exercise. Results were compared with those obtained in 11 male sport students (average age 26.4 [23-30] years), who had similarly trained for 5.6 +/- 1.3 h/week. RESULTS: The paraplegics had a significantly smaller LVV than the controls (771 +/- 84 ml vs 976 +/- 84 ml) and smaller SV (83 +/- 13 ml vs 104 +/- 11ml), with comparable WT. Paraplegics achieved significantly lower maximal exercise (145 +/- 23.7 vs 160 +/- 28.2) and maximal HR (177 +/- 12 vs 170 +/- 9) were not significantly different at the various exercise steps. CONCLUSION: Paraplegia decreases cardiac dimensions and function. Long-term physical exercise achieves results comparable with those of untrained but not of trained healthy controls. Physically active paraplegics showed physiological cardiovascular and metabolic reactions to exercise.     

Bone density and fracture risk in men

We evaluated different definitions of osteoporosis in a population-based sample of 348 men (age 22-90 years) compared with 351 women (age 21-93 years). Thirty-six men (10%) and 46 women (13%) had a history of osteoporotic fracture (hip, spine, or distal forearm due to moderate trauma at >/= age 35). In logistic regression analysis, osteoporotic fracture risk was associated with bone mineral density (BMD) at all sites (neck, trochanter, total hip, lumbar spine, and total wrist) in both genders (p < 0.001) except spinal BMD in men. After adjusting for age, total hip BMD was the strongest predictor of fracture risk in women (odds ratio [OR] per 1 SD decline, 2.4; 95% confidence interval [CI], 1.6-3.7), while wrist BMD was best in men (OR, 1.5; 95% CI, 1.1-2.0). Among men but not women, bone mineral apparent density (BMAD) was a better predictor of fracture than BMD (wrist BMAD OR, 1.7; 95% CI, 1.3-2.3). Hip BMD/BMAD decreased linearly from age 20 years onward in both genders, while spinal BMD/BMAD declined after age 40 in women but not in men. In both genders, total wrist BMD/BMAD decreased after age 50. By World Health Organization criteria, the age-adjusted prevalence of osteoporosis at the hip, spine, or wrist was 35% among women >/=50 years of age. A similar approach (BMD > 2.5 SD below the young male mean) produced an osteoporosis prevalence rate in men >/=50 years of age of 19%. Thus, bone density predicts fracture risk in men as it does in women, and the prevalence of osteoporosis in men, using sex-specific normal values, is substantial. These observations indicate a need for better prevention and treatment strategies for men.     

Bone mass and muscle strength in female college athletes (runners and swimmers)

OBJECTIVE: To determine whether female college athletes had increased muscle strength and bone mass in comparison with age-matched nonathletic female subjects and, if so, whether participation in weight-bearing versus non-weight-bearing exercise made a difference. MATERIAL AND METHODS: We performed a comparative statistical analysis of the bone mineral density (BMD) of the total body, lumbar spine, and femoral neck, maximal oxygen uptake (VO2max), muscle strength, and level of physical activity in 21 runners, 22 swimmers, and 20 control subjects. The study participants were female college students, 18 to 24 years old, who had had more than 8 normal menstrual cycles during the past year. RESULTS: Statistical analyses showed significantly higher VO2max in the two athletic study groups than in the control subjects (P < 0.0001). No significant difference in BMD was noted among the three groups. Total body BMD (r = 0.30; P = 0.02) and femoral neck BMD (r = 0.39; P = 0.002) were positively correlated with weight-bearing activity but not with non-weight-bearing activity. VO2Max (an index of physical fitness) was positively correlated with femoral neck BMD (r = 0.33; P = 0.009) and trochanteric BMD (r = 0.29; P = 0.021). Shoulder muscle strength (determined by isokinetic dynamometry) was positively correlated with total body BMD (r = 0.34; P = 0.007) and lumbar spine BMD (r = 0.28; P = 0.028). Swimmers had higher muscle strength in the back and upper extremities than did runners and control subjects. Hip girdle muscle strength was not significantly different among the three groups. Total body BMD had a positive correlation with percentage of body fat and height. Lumbar spine BMD was higher in subjects who had previously used oral contraceptives. The athletes had a lower percentage of body fat, were less likely to have used oral contraceptives, and had fewer years of normal menses than did the control subjects. CONCLUSION: Our study shows that (1) total body BMD and femoral neck BMD were significantly higher in the study group that performed weight-bearing exercises than in control subjects, (2) swimming exercise had no effect on BMD, and (3) although swimming is not a bone-building exercise, it can significantly improve shoulder, back, and grip muscle strength.     

Apoptosis and ovarian function

For decades, the mechanisms responsible for germ cell depletion from the ovary, either directly during the perinatal period or indirectly via follicular atresia during postnatal life, have remained relatively obscure. The recent application of sensitive biochemical techniques for the study of cell death to the analysis of ovarian function has revealed that these two events, as well as a third instance of ovarian cell degeneration (luteolysis), are dependent upon the activation of physiological cell death mechanisms. It is therefore hypothesized that the controlled deletion of ovarian cell populations is accomplished via activation of a 'universal' pathway of cellular suicide involving altered expression of a conserved cohort of genes. The identity of the hormonal and intracellular effectors responsible for the coordination of life and death decisions made by ovarian cells during development as well as the biological and clinical implications of gene-directed cell death in the ovary are explored in this review.     

Bone density profiles and osteoporosis incidence in Irish females

1725 Irish females aged 15-70+ were included in this analysis to establish the group bone mineral density (BMD) profiles. Each subject was screened for 27 risk factors by questionnaire. Subjects were segregated into normal (N) and non-normal (NN) subgroups on the basis of the questionnaire. BMD of lumbar spine and hip were measured by dual energy X ray absorptiometry (DEXA). A substantial difference in BMD at all sites was observed between subgroups even following adjustment for body mass index and years of exposure to oestrogen. In the subgroup designated as non-normal 42%, 54%, 72% and 69% of those studied had spinal BMD levels > 2SD below mean peak at 55-59, 60-64, 65-69 and 70+ respectively. In comparison, similar age cohorts in the subgroup designated normal were 26%, 46%, 44% and 68% respectively. A marked difference was also observed in the younger age groups (15-34) where the percentage of individuals with spinal BMD levels > 2SD below mean peak was < 1.9% for N and 18.8% for NN. The results of this study suggest that the use of a questionnaire may be a valuable low cost screening tool in the younger groups.     

Bone density and local growth factors in generalized osteoarthritis

Osteoarthritis is usually considered to be a primary disorder of chondrocyte function with secondary changes in bones. However, a defect in the subchondral bone resulting in loss of its shock absorbing capacity could transfer the stress of loading directly to the articular cartilage with secondary changes in the cartilage. Review of histomorphometric and bone densitometric studies at sites of osteoarthritis at the hip or knee revealed that cartilage fibrillation could not be dissociated from bony changes even in the earliest stages of osteoarthritis and that subchondral trabeculae are thickened and more spaced in osteoarthritis. Microfractures of subchondral trabecular bone were less frequently seen in osteoarthritis compared to controls. Changes of the tidemark were found to be multiform and metabolically active in the osteoarthritic process. Endochondral ossification depletes the calcified cartilage at the cartilage/bone interface and the tidemark has been thought of as a calcification front advancing in the direction of non-calcified cartilage. Duplication of the tidemark is cited as evidence of this advancement. In the few experimental animal studies of subchondral bone in osteoarthritis, thicker trabeculae which were closer together were found in guinea pigs already when only mild cartilage changes were present. In the dog, with cruciate ligament transection, changes in bone were later than in the cartilage, but the changes in bone could still contribute to the progression of osteoarthritis. To study if bone changes may precede injury to the cartilage and if metabolic and systemic influences can also alter the subchondral bone, rendering it less able to withstand normal mechanical stresses, bone at different sites in the body has been studied extensively by the authors. Epidemiological and case control studies have revealed that osteoarthritis cases have more bone at all sites than expected and that bone in cases with generalized osteoarthritis shows both quantitative and qualitative differences, including increased contents of growth factors and hypermineralization. These findings suggest that a more generalized bone alteration may be the basis of the pathogenesis of osteoarthritis.     

Left ventricular function during dynamic exercise in untrained and moderately trained subjects

The influence of exercise training on left ventricular function at rest (R), at anaerobic threshold (AT), and during peak exercise (PE) was evaluated in 12 healthy untrained and 13 trained (T) subjects who underwent Doppler echocardiography at R and radionuclide ventriculography at R and during exercise. The end-diastolic volume and stroke volume were significantly higher in the T group than in the untrained group at R. The ejection fraction rose significantly from R to AT and from AT to PE (80.0 +/- 0.84 vs. 83.6 +/- 0.91%), but no significant difference was observed between groups. The peak diastolic filling rate rose significantly during exercise, with a further significant increase observed in the T group (AT, 6.38 +/- 0.40 vs. 5.01 +/- 0.16 end-diastolic counts/s; PE, 8.24 +/- 0.42 vs. 7.15 +/- 0.35 end-diastolic counts/s). The percent variation of minimal systolic counts fell significantly at AT and PE in relation to R. Our data demonstrate that exercise training produces a significant increase in peak diastolic filling rate but no change in systolic function during exercise and that metabolic acidosis caused by exercise does not limit systolic function.     

Bone mineral density in elite junior Olympic weightlifters

The purpose of this study was to examine the relationship of bone mineral density (BMD) to muscular strength in highly trained young male athletes in order to gain insights concerning the influence of heavy resistance training on BMD. Twenty-five elite junior weightlifters (age, 17.4 +/- 1.4 yr) and 11 age-matched controls (16.9 +/- 1.1 yr) volunteered for this investigation. Measurements of BMD (g.cm-2) utilizing dual energy x-ray absorptiometry were obtained for the lumbar spine (L2-4) and the proximal femur (neck; trochanter, Ward's triangle). The BMD values for the junior lifters were found to be significantly greater at all sites for the junior weightlifters compared with their age-matched control group. The BMD values of the spine and femoral neck of the junior weightlifters when compared with adult reference data (i.e., 20-39 yr old men) were found to be significantly greater. Both simple and multiple regression analyses demonstrated significant relationships of BMD with strength accounting for 30-65% of the variance. These data suggest that in elite junior weightlifters, muscle strength, highly specific to the sport of weightlifting, has a major influence on BMD due to the influence of the chronic overloads experienced in training.     

Bone mineral density in periodontally healthy and edentulous postmenopausal women

(Osteoporosis is the most common metabolic disease among postmenopausal women. Reduced masticatory function caused by tooth loss may be a contributing risk factor of osteoporosis. The present study examined the effect of dentate state on skeletal bone mineral density (BMD) in postmenopausal women. Fourteen periodontally healthy dentate subjects (group H; mean age: 64.0 + 5.5 years) and 12 edentulous subjects (group E; mean age: 67.1 + 2.9 years) were randomly selected from the clinics of the departments of Periodontology and Gerodontology, respectively. Informed consent was obtained from all participants. BMD of the lumbar spine (L2-L4) was measured by dual energy x-ray absorptiometry. In addition, occlusal force was measured in 11 group H subjects and 8 group E subjects by using an occlusal diagnostic system. Risk factors associated with osteoporosis including age, calcium intake, physical activity, and cigarette smoking and causes of tooth loss were assessed by interview and questionnaire sent to all participants. The BMD of group H was 1.07 t 0.21 g/cm2 and that of group E was 0.89 + 0.17 g/cm2, which was significantly different(P< 0.05). The occlusal force of group H and E patients was 312.4 + 148 Nand 56.3 + 36 N, respectively, which was significantly different (P< 0.05). Risk factors such as calcium intake, physical activity, and smoking did not differ significantly between the 2 groups. Thus, the periodontally healthy dentate women, who showed about 6 times higher occlusal force than edentulous women, maintained significantly higher BMD of the lumbar spine than edentulous women. Our results suggest that sufficient masticatory function with periodontally healthy dentition may inhibit or delay the progress of osteoporotic change in skeletal bone or that edentulous women may be more susceptible to osteoporosis.     

Loss of ovarian function promotes angiogenesis in human ovarian carcinoma

We show here that elevated levels of gonadotropins (luteinizing hormone and follicle stimulating hormone), as found in menopause or after ovariectomy, promote growth of human ovarian carcinoma by induction of tumor angiogenesis. Human epithelial ovarian cancer tumors progressed faster in ovariectomized mice. This induced growth could be attributed to the elevated levels of gonadotropins associated with loss of ovarian function because direct administration of gonadotropins also was effective in promoting tumor progression in vivo. On the other hand, gonadotropins had no direct effect on the proliferation of human ovarian cancer cells in vitro. Using MRI, we demonstrated that ovariectomy significantly (P < 0.02) induces neovascularization of human ovarian carcinoma spheroids implanted in nude mice. Moreover, conditioned medium of gonadotropin-treated human ovarian carcinoma cells showed increased mitogenic activity to bovine endothelial cells, and this activity could be blocked by neutralizing antibodies against luteinizing hormone and against vascular endothelial growth factor. Accordingly, gonadotropin stimulation resulted in a dose-dependent-induced expression of vascular endothelial growth factor in monolayer culture as well as in the outer proliferating cells of human ovarian cancer spheroids. These results demonstrate the significance of the elevated levels of gonadotropins, as found in menopause and in all ovarian cancer patients, on the progression of ovarian cancer and could explain the protective effect of estrogen replacement therapy. Based on these results, we suggest that hormonal therapy aimed at lowering the circulating levels of gonadotropins may possibly prolong remission in ovarian cancer by extending tumor dormancy.     

Bone mineral density in pediatric patients with idiopathic hypercalciuria

Between October 1993 and April 1995, a total of 77 neonates requiring mechanical ventilation were enrolled in this study and were randomly divided into two groups. Group A consisted of 31 premature infants (mean birthweight 1.36 +/- 0.29 kg) with respiratory distress syndrome (RDS) and seven neonates (mean birthweight 3.2 +/- 0.5 kg) with meconium aspiration syndrome (MAS). Group B consisted of 31 premature infants (mean birthweight 1.31 +/- 0.3 kg) with RDS and eight neonates (mean birthweight 3.3 +/- 0.5 kg) with MAS. Infants in group A received synchronized intermittent mandatory ventilation (SIMV) and infants in group B received conventional intermittent mandatory ventilation (CIMV) therapy. In premature infants with RDS, our data showed: (i) the duration of ventilation was significantly shorter (P < 0.05) in the synchronized group (156 +/- 122 h) compared to the conventional group (242 +/- 175 h); (ii) significantly fewer (P < 0.05) patients required reintubation in the synchronized group than in the conventional group (three vs 11 patients); (iii) incidence of severe intraventricular hemorrhage (grades 3 and 4) was significantly lower (P < 0.05) in the synchronized group compared to the conventional group (one vs seven patients); (iv) incidence of bronchopulmonary dysplasia was significantly lower (P < 0.05) in the synchronized group than in the control group (one vs seven patients). In neonates with MAS, our data showed no significant difference (P < 0.05) on duration of ventilation, incidence of reintubation, incidence of pneumothorax or mortality rate between synchronized and control groups.     

Bone density and skeletal metabolism in patients with orthotopic ileal neobladder

The interposition of a bowel segment as a bladder substitute into the urinary tract may result in impaired calcium metabolism. We studied 25 male patients (aged 45 to 77 yr) who had undergone a Vescica Ileale Padovana (VIP) reconstruction following cystectomy 29 to 75 mo before. Bone mineral density of the spine and femur was measured by dual x-ray absorptiometry. Blood and 24-h urine samples were analyzed for the main parameters of bone metabolism. Sixteen healthy men were enrolled as a control group. Although blood pH did not differ between patients and control subjects, VIP subjects showed lower levels of plasma HCO3- (P < 0.005) and higher serum chloride (P < 0.001). Bone alkaline phosphatase was higher (P < 0.001), and urine calcium, phosphate, and creatinine levels were lower in VIP patients (P < 0.01, P < 0.01, and P < 0.05, respectively). Bone mineral density at the femoral neck (P < 0.03) and Ward's triangle (P < 0.05) was decreased in VIP patients. When subdivided according to time since operation, patients who had the ileal neobladder implanted for a shorter period of time showed lower blood pH (P < 0.03) and urine calcium (P < 0.05) levels and higher urinary hydroxyproline (P < 0.02). Duration of the ileal neobladder was positively correlated with PTH (r = 0.46, P < 0.03) and blood pH (r = 0.47, P < 0.02). Furthermore, pH values were positively correlated with urine calcium (r = 0.48, P < 0.02). In conclusion, in patients with ileal neobladder, a mild metabolic acidosis is responsible for an increased bone turnover and lower bone mass. Moreover, a decrease over time in the absorption capacity of the ileal pouch might result in calcium malabsorption, which represents an additional risk factor for reduced bone mass in these patients.     

Population density and endocrine function.

Population density affects endocrine function, being positively related to adrenal hypertrophy and adrenocortical activity and negatively related to gonadal and mammary activity. There is some evidence of marked genetic differences in response as well as some evidence that population size is only indirectly a causative agent. From Psyc Abstracts 36:04:4EO41T. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Bone mineral density assessment in children with inflammatory bowel disease

BACKGROUND & AIMS: Children with inflammatory bowel disease (IBD) are at risk for osteoporosis because of undernutrition, delayed puberty, and prolonged corticosteroid use. The aim of this study was to compare bone mineral density (BMD) in children with IBD with that in normal children and to assess the effects of nutritional and hormonal factors and corticosteroid dosages on BMD. METHODS: One hundred sixty-two subjects (99 with IBD and 63 healthy sibling controls) were enrolled. Patients underwent anthropometric assessment, pubertal staging, bone age radiography, and BMD assessment by dual energy x-ray absorptiometry of the lumbar spine, femoral neck, and radius. Laboratory evaluations included serum calcium, phosphate, alkaline phosphatase, 25-hydroxyvitamin D, 1,25-dihydroxyvitamin D, parathyroid hormone, osteocalcin, urinary N-telopeptides, albumin, insulin-like growth factor I, and testosterone or estradiol. Cumulative corticosteroid doses were calculated. RESULTS: BMD Z scores at the lumbar spine and femoral neck were lower in patients with IBD, and lower in those with Crohn's disease compared with those with ulcerative colitis. Low BMD persisted after correction for bone age in girls with Crohn's disease (lumbar spine, P = 0.004; femoral neck, P = 0.002). Cumulative corticosteroid dose was a significant predictor of reduced BMD. BMD did not correlate with measures of calcium homeostasis, except elevated serum phosphate and urine calcium levels in girls. CONCLUSIONS: Low BMD occurs in children with IBD (more in Crohn's disease than in ulcerative colitis), especially pubertal and postpubertal girls. Cumulative corticosteroid dose is a predictor of low BMD, but other factors in Crohn's disease remain undetermined.