Risk factors for decreased bone density in premenopausal women

Osteoporosis is a major health problem. Little is known about the risk factors in premenopause. Sixty 40-50-year old patients with regular menses were studied cross-sectionally. None of the patients were on drugs known to interfere with bone mass. Patients answered a dietary inquiry and had their bone mineral density (BMD) measured. The Z scores were used for the comparisons. A blood sample was taken for the determination of FSH, SHBG, estradiol, testosterone, calcium and alkaline phosphatase. Calcium and creatinine were measured in 24-h urine. A Z score less than -1 was observed for the lumbar spine of 14 patients (23.3%), and for the femur of 24 patients (40%). Patients with a Z score less than -1 for the lumbar spine were older than patients with a Z score ³-1 (45.7 vs 43.8 years) and presented higher values of alkaline phosphatase (71.1 ± 18.2 vs 57.1 ± 14.3 IU/l). Multiple regression analysis showed that a lower lumbar spine BMD was associated with higher values of alkaline phosphatase, lower calcium ingestion, a smaller body mass index (BMI), less frequent exercising, and older age. The patients with a Z score less than -1 for the femur were shorter than patients with a Z score ³-1 (158.2 vs 161.3 cm). Multiple regression analysis showed that a lower femoral BMD was associated with lower BMI, higher alkaline phosphatase and caffeine intake, and less frequent exercising. A lower than expected BMD was observed in a significant proportion of premenopausal women and was associated with lower calcium intake, relatively lower physical activity and lower BMI. We conclude that the classical risk factors for osteoporosis may be present before ovarian failure, and their effect may be partly independent of estrogen levels.

Reduced bone mineral density in men after heart transplantation

Heart transplantation is associated with rapid bone loss and an increased prevalence and incidence of fractures. The aim of the present study was to compare the bone mineral density (BMD) of 30 heart transplant (HT) recipients to that of 31 chronic heart failure (CHF) patients waiting for transplantation and to determine their biochemical markers of bone resorption and hormone levels. The BMD of lumbar spine and proximal femur was determined by dual-energy X-ray absorptiometry. Anteroposterior and lateral radiographs of the thoracic and lumbar spine were also obtained. The mean age of the two groups did not differ significantly. Mean time of transplantation was 25.4 ± 21.1 months (6 to 88 months). Except for the albumin levels, which were significantly higher, and magnesium levels, which were significantly lower in HT patients when compared to CHF patients, all other biochemical parameters and hormone levels were within the normal range and similar in the two groups. Both groups had lower BMD of the spine and proximal femur compared to young healthy adults. However, the mean BMD of HT patients was significantly lower than in CHF patients at all sites studied. Bone mass did not correlate with time after transplantation or cumulative dose of cyclosporine A. There was a negative correlation between BMD and the cumulative dose of prednisone. These data suggest that bone loss occurs in HT patients mainly due to the use of corticosteroids and that in 30% of the patients it can be present before transplantation. It seems that cyclosporine A may also play a role in this loss.

Polymorphisms of the low-density lipoprotein receptor gene in Brazilian individuals with heterozygous familial hypercholesterolemia

Familial hypercholesterolemia (FH) is a metabolic disorder inherited as an autosomal dominant trait characterized by an increased plasma low-density lipoprotein (LDL) level. The disease is caused by several different mutations in the LDL receptor gene. Although early identification of individuals carrying the defective gene could be useful in reducing the risk of atherosclerosis and myocardial infarction, the techniques available for determining the number of the functional LDL receptor molecules are difficult to carry out and expensive. Polymorphisms associated with this gene may be used for unequivocal diagnosis of FH in several populations. The aim of our study was to evaluate the genotype distribution and relative allele frequencies of three polymorphisms of the LDL receptor gene, HincII1773 (exon 12), AvaII (exon 13) and PvuII (intron 15), in 50 unrelated Brazilian individuals with a diagnosis of heterozygous FH and in 130 normolipidemic controls. Genomic DNA was extracted from blood leukocytes by a modified salting-out method. The polymorphisms were detected by PCR-RFLP. The FH subjects showed a higher frequency of A+A+ (AvaII), H+H+ (HincII1773) and P1P1 (PvuII) homozygous genotypes when compared to the control group (P<0.05). In addition, FH probands presented a high frequency of A+ (0.58), H+ (0.61) and P1 (0.78) alleles when compared to normolipidemic individuals (0.45, 0.45 and 0.64, respectively). The strong association observed between these alleles and FH suggests that AvaII, HincII1773 and PvuII polymorphisms could be useful to monitor the inheritance of FH in Brazilian families.

Bone mineral density in Brazilian men 50 years and older

Bone mineral density (BMD) in the lumbar spine (LSBMD), femoral neck (FNBMD) and whole body (WBBMD) and whole body tissue composition were evaluated in 288 Brazilian men 50 years and older, 80% white and 20% Mulattoes. Age was inversely correlated with WBBMD (r = -0.20) and FNBMD (r = -0.21) but not with LSBMD (r = 0.03). Body mass index and weight showed a strong positive correlation with WBBMD (r = 0.48 and 0.54), LSBMD (r = 0.37 and 0.45) and FNBMD (r = 0.42 and 0.48). Correlation with height was positive but weaker. No significant bone loss at the lumbar spine level was observed as the population aged. FNBMD and WBBMD decreased significantly only in the last decade (age 70-79) studied. BMD was higher for Brazilian men as compared to Brazilian women at all sites. No significant differences were observed between Brazilian and the US/European male population for BMD in the femoral neck. BMD measured by dual-energy X-ray absorptiometry in South American men is reported here for the first time. A decrease in FNBMD was detected only later in life, with a pattern similar to that described for the US/European male population.

Bone mineral density of the lumbar spine of Brazilian children and adolescents aged 6 to 14 years

The authors performed a study of bone mass in eutrophic Brazilian children and adolescents using dual-energy X-ray absorptiometry (DXA) in order to obtain curves for bone mineral content (BMC) and bone mineral density (BMD) by chronological age and correlate these values with weight and height. Healthy Caucasian children and adolescents, 120 boys and 135 girls, 6 to 14 years of age, residents of São Paulo, Brazil, were selected from the Pediatric Department outpatient clinic of Hospital São Paulo (Universidade Federal de São Paulo). BMC, BMD and the area of the vertebral body of the L2-L4 segment were obtained by DXA. BMC and BMD for the lumbar spine (L2-L4) presented a progressive increase between 6 and 14 years of age in both sexes, with a distribution that fitted an exponential curve. We identified an increase of mineral content in female patients older than 11 years which was maintained until 13 years of age, when a new decrease in the velocity of bone mineralization occurred. Male patients presented a period of accelerated bone mass gain after 11 years of age that was maintained until 14 years of age. At 14 years of age the mean BMD values for boys and girls were 0.984 and 1.017 g/cm², respectively. A stepwise multiple regression analysis of paired variables showed that the "vertebral area-age" pair was the most significant in the determination of BMD values and the introduction of a third variable (weight or height) did not significantly increase the correlation coefficient.

Effects of lipopolysaccharide on low- and high-density cultured rabbit vascular smooth muscle cells: differential modulation of nitric oxide release, ERK1/ERK2 MAP kinase activity, protein tyrosine phosphatase activity, and DNA synthesis

Previous studies have shown that exogenously generated nitric oxide (NO) inhibits smooth muscle cell proliferation. In the present study, we stimulated rabbit vascular smooth muscle cells (RVSMC) with E. coli lipopolysaccharide (LPS), a known inducer of NO synthase transcription, and established a connection between endogenous NO, phosphorylation/dephosphorylation-mediated signaling pathways, and DNA synthesis. Non-confluent RVSMC were cultured with 0, 5, 10, or 100 ng/ml of the endotoxin. NO release was increased by 86.6% (maximum effect) in low-density cell cultures stimulated with 10 ng/ml LPS as compared to non-stimulated controls. Conversely, LPS (5 to 100 ng/ml) did not lead to enhanced NO production in multilayered (high density) RVSMC. DNA synthesis measured by thymidine incorporation showed that LPS was mitogenic only to non-confluent RVSMC; furthermore, the effect was prevented statistically by aminoguanidine (AG), a potent inhibitor of the inducible NO synthase, and oxyhemoglobin, an NO scavenger. Finally, there was a cell density-dependent LPS effect on protein tyrosine phosphatase (PTP) and ERK1/ERK2 mitogen-activated protein (MAP) kinase activities. Short-term transient stimulation of ERK1/ERK2 MAP kinases was maximal at 12 min in non-confluent RVSMC and was prevented by preincubation with AG, whereas PTP activities were inhibited in these cells after 24-h LPS stimulation. Conversely, no significant LPS-mediated changes in kinase or phosphatase activities were observed in high-density cells. LPS-induced NO generation by RVSMC may switch on a cell density-dependent proliferative signaling cascade, which involves the participation of PTP and the ERK1/ERK2 MAP kinases.

Plasma and testicular testosterone levels, volume density and number of Leydig cells and spermatogenic efficiency of rabbits

Plasma and tissue testosterone concentrations were determined by radioimmunoassay in 12 eight-month-old sexually mature New Zealand White rabbits and evaluated for possible associations with spermatogenic efficiency as well as with volume density and number of Leydig cells. Testicular tissue was processed histologically and histometry was performed in order to quantify germ cells, Sertoli cells and Leydig cells. Spermatogenic efficiency, reported as the ratios among germ cells (spermatogonia, primary spermatocytes and round spermatids) and by the ratio of germ cells to Sertoli cells, was not associated with testosterone levels. However, Leydig cell parameters such as number of Leydig cells per gram of testis, total number of Leydig cells per testis and percent cell volume of Leydig cell nuclei were correlated significantly with testosterone levels. The statistically significant correlation (r = 0.82, P<0.05) observed between testosterone levels and the number of Leydig cells per gram of testis suggests that, in the rabbit, the latter parameter can serve as a criterion for monitoring testosterone levels in this species under normal conditions.

Bone mineral density in young women of the city of São Paulo, Brazil: correlation with both collagen type I alpha 1 gene polymorphism and clinical aspects

Osteoporosis is a multifactorial disease with great impact on morbidity and mortality mainly in postmenopausal women. Although it is recognized that factors related to life-style and habits may influence bone mass formation leading to greater or lower bone mass, more than 85% of the variation in bone mineral density (BMD) is genetically determined. The collagen type I alpha 1 (COLIA1) gene is a possible risk factor for osteoporosis. We studied a population of 220 young women from the city of São Paulo, Brazil, with respect to BMD and its correlation with both COLIA1 genotype and clinical aspects. The distribution of COLIA1 genotype SS, Ss and ss in the population studied was 73.6, 24.1 and 2.3%, respectively. No association between these genotypes and femoral or lumbar spine BMD was detected. There was a positive association between lumbar spine BMD and weight (P<0.0001), height (P<0.0156), and body mass index (BMI) (P<0.0156), and a negative association with age at menarche (P<0.0026). There was also a positive association between femoral BMD and weight (P<0.0001), height (P<0.0001), and BMI (P<0.0001), and a negative correlation with family history for osteoporosis (P<0.041). There was no association between the presence of allele s and reduced BMD. We conclude that a family history of osteoporosis and age at menarche are factors that may influence bone mass in our population.

Bone mineral density in juvenile systemic lupus erythematosus

We evaluated spine bone mineral density (BMD) in Brazilian children with juvenile systemic lupus erythematosus (JSLE) in order to detect potential predictors of reduction in bone mass. A cross-sectional study of BMD at the lumbar spine level (L2-L4) was conducted on 16 female JSLE patients aged 6-17 years. Thirty-two age-matched healthy girls were used as control. BMD at the lumbar spine was measured by dual-energy X-ray absorptiometry. Weight, height and pubertal Tanner stage were determined in patients and controls. Disease duration, mean daily steroid doses, mean cumulative steroid doses and JSLE activity measured by the systemic lupus erythematosus disease activity index (SLEDAI) were determined for all JSLE patients based on their medical charts. All parameters were used as potential determinant factors for bone loss. Lumbar BMD tended to be lower in the JSLE patients, however, this difference was not statistically significant (P = 0.10). No significant correlation was observed in JSLE girls between BMD and age, height, Tanner stage, disease duration, corticosteroid use or disease activity. We found a weak correlation between BMD and weight (r = 0.672). In the JSLE group we found no significant parameters to correlate with reduced bone mass. Disease activity and mean cumulative steroid doses were not related to BMD values. We did not observe reduced bone mass in female JSLE.

Hormone replacement therapy increases levels of antibodies against heat shock protein 65 and certain species of oxidized low density lipoprotein

Hormone replacement therapy (HRT) reduces cardiovascular risks, although the initiation of therapy may be associated with transient adverse ischemic and thrombotic events. Antibodies against heat shock protein (Hsp) and oxidized low density lipoprotein (LDL) have been found in atherosclerotic lesions and plasma of patients with coronary artery disease and may play an important role in the pathogenesis of atherosclerosis. The aim of the present study was to assess the effects of HRT on the immune response by measuring plasma levels of antibodies against Hsp 65 and LDL with a low and high degree of copper-mediated oxidative modification of 20 postmenopausal women before and 90 days after receiving orally 0.625 mg equine conjugate estrogen plus 2.5 mg medroxyprogesterone acetate per day. HRT significantly increased antibodies against Hsp 65 (0.316 ± 0.03 vs 0.558 ± 0.11) and against LDL with a low degree of oxidative modification (0.100 ± 0.01 vs 0.217 ± 0.02) (P<0.05 and P<0.001, respectively, ANOVA). The hormone-mediated immune response may trigger an inflammatory response within the vessel wall and potentially increase plaque burden. Whether or not this immune response is temporary or sustained and deleterious requires further investigation.

Impact of congenital calcitonin deficiency due to dysgenetic hypothyroidism on bone mineral density

The objective of the present study was to determine the effect of chronic calcitonin deficiency on bone mass development. The results of 11 patients with thyroid dysgenesis (TD) were compared to those of 17 normal individuals (C) and of 9 patients with other forms of hypothyroidism (OH): 4 with hypothyroidism due to inborn errors of thyroid hormone synthesis and 5 with Hashimoto's thyroiditis. The subjects received an intravenous calcium stimulus and blood was collected for the determination of ionized calcium (Ca2+), calcitonin, and intact parathyroid hormone. Bone mineral density (BMD) was determined by dual-energy X-ray absorptiometry. After calcium administration the levels of Ca2+ in the two groups of hypothyroidism were significantly higher than in the normal control group (10 min after starting calcium infusion: C = 1.29 ± 0.08 vs TD = 1.34 ± 0.03 vs OH = 1.34 ± 0.02 mmol/l; P < 0.05), and only the TD group showed no calcitonin response (5 min after starting calcium infusion: C = 27.9 ± 5.8 vs TD = 6.6 ± 0.3 vs OH = 43.0 ± 13.4 ng/l). BMD values did not differ significantly between groups (L2-L4: C = 1.116 ± 0.02 vs TD = 1.109 ± 0.03 vs OH = 1.050 ± 0.04 g/cm²). These results indicate that early deficiency of calcitonin secretion has no detrimental effect on bone mass development. Furthermore, the increased calcitonin secretion observed in patients with inborn errors of thyroid hormone biosynthesis does not confer any advantage in terms of BMD.

Cardiovascular complications and increased levels of circulating modified low density lipoprotein in HIV patients and patients with lipodystrophy

The introduction of highly active antiretroviral therapy (HAART) for patients infected with HIV has significantly prolonged the life expectancy and to some extent has restored a functional immune response. However, the premature introduction of HAART has led to a significant and alarming increase in cardiovascular complications, including myocardial infarction and the appearance of abnormal distribution of body fat seen as lipodystrophy. One key element in the development of ischemic coronary artery disease is the presence of circulating and tissue-fixed modified low density lipoprotein (mLDL) that contributes to the initiation and progression of arterial lesions and to the formation of foam cells. Even though not completely elucidated, the most likely mechanism involves mLDL in the inflammatory response and the induction of a specific immune response against mLDL. Circulating antibodies against mLDL can serve as an indirect marker of the presence of circulating and vessel-fixed mLDL. In the present study, we measured antibodies to mLDL and correlated them with immune status (i.e., number of CD4+ T cells) in 59 HIV patients and with the clinical manifestation of lipodystrophy in 10 patients. We observed a significant reduction in anti-mLDL antibody levels related both to lipodystrophy and to an immunocompromised state in HIV patients. We speculate that these antibodies may explain in part the rapid development of ischemic coronary artery disease in some patients.

Bone mineral density of Brazilian girls with juvenile dermatomyositis

We measured bone mineral density (BMD) in girls with juvenile dermatomyositis (JDM) considering multiple factors in order to determine if it could be used as a predictor of reduction in bone mass. A cross-sectional study of lumbar spine BMD (L2-L4) was conducted on 10 girls aged 7-16 years with JDM. A group of 20 age-matched healthy girls was used as control. Lumbar spine BMD was measured by dual-energy X-ray absorptiometry. Weight, height and pubertal Tanner stage were determined in all patients and controls. Duration of disease and mean daily and cumulative steroid doses were calculated for all patients on the basis of their medical charts. JDM activity was determined on the basis of the presence of muscle weakness, cutaneous vasculitis and/or elevation of serum concentration of one or more skeletal muscle enzymes. Seven patients demonstrated osteopenia or osteoporosis. Lumbar BMD was significantly lower in the JDM patients than the age-matched healthy control girls (0.712 vs 0.878, respectively; Student t-test, P = 0.041). No significant correlation between BMD and age, height, Tanner stage, disease duration, corticosteroid use, or disease activity was observed in JDM girls, but a correlation was observed between BMD and weight (Pearson's correlation coefficient, r = 0.802). Patients with JDM may be at risk for a significant reduction in BMD that might contribute to further skeletal fragility. Our results suggest that reduced bone mass in JDM may be related to other intrinsic mechanisms in addition to steroid treatment and some aspects of the disease itself may contribute to this condition.

Density, proportion, and dendritic coverage of retinal ganglion cells of the common marmoset (Callithrix jacchus jacchus)

We performed a quantitative analysis of M and P cell mosaics of the common-marmoset retina. Ganglion cells were labeled retrogradely from optic nerve deposits of Biocytin. The labeling was visualized using horseradish peroxidase (HRP) histochemistry and 3-3'diaminobenzidine as chromogen. M and P cells were morphologically similar to those found in Old- and New-World primates. Measurements were performed on well-stained cells from 4 retinas of different animals. We analyzed separate mosaics for inner and outer M and P cells at increasing distances from the fovea (2.5-9 mm of eccentricity) to estimate cell density, proportion, and dendritic coverage. M cell density decreased towards the retinal periphery in all quadrants. M cell density was higher in the nasal quadrant than in other retinal regions at similar eccentricities, reaching about 740 cells/mm² at 2.5 mm of temporal eccentricity, and representing 8-14% of all ganglion cells. P cell density increased from peripheral to more central regions, reaching about 5540 cells/mm² at 2.5 mm of temporal eccentricity. P cells represented a smaller proportion of all ganglion cells in the nasal quadrant than in other quadrants, and their numbers increased towards central retinal regions. The M cell coverage factor ranged from 5 to 12 and the P cell coverage factor ranged from 1 to 3 in the nasal quadrant and from 5 to 12 in the other quadrants. These results show that central and peripheral retinal regions differ in terms of cell class proportions and dendritic coverage, and their properties do not result from simply scaling down cell density. Therefore, differences in functional properties between central and peripheral vision should take these distinct regional retinal characteristics into account.

Inverting ionospheric D-region electron density pro-file from riometer measurement

The aim of this work is to invert the ionospheric electron density profile from Riometer (Relative Ionospheric opacity meter) measurement. The newly Riometer instrument KAIRA (Kilpisjärvi Atmospheric Imaging Receiver Array) is used to measure the cosmic HF radio noise absorption that taking place in the D-region ionosphere between 50 to 90 km. In order to invert the electron density profile synthetic data is used to feed the unknown parameter Neq using spline height method, which works by taking electron density profile at different altitude. Moreover, smoothing prior method also used to sample from the posterior distribution by truncating the prior covariance matrix. The smoothing profile approach makes the problem easier to find the posterior using MCMC (Markov Chain Monte Carlo) method.