Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C0028754 (obesity)
 124,988 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Osteomalacia is characterized by large osteoid seams and a preserved volume of bone trabeculae. The mineralization of newly formed bone requires adequate concentrations of calcium and phosphate: the Ca.P product has been regarded as a useful, empirical diagnostic test of osteomalacia. It decreases in patients with osteomalacia mainly because they have very low plasma phosphate levels. At present total body bone mineral and total body bone density can be directly measured by whole body absorptiometry, which indicates the lowest total mineral content of the skeleton which can increase quickly after adequate treatment. The main symptoms of osteomalacia are: bone pain; muscular weakness (commonly as pelvic girdle myopathy); Looser-Milkman pseudofractures or more often a pattern of generalized demineralization at X-ray. The main biochemical parameters in osteomalacia include: defective calcium absorption with hypocalcemia and hypocalciuria; defective intestinal phosphate absorption with hypophosphatemia; there is often increased renal phosphate clearance due to hypocalcemia and secondary hyperparathyroidism; elevated alkaline phosphatase and osteocalcin levels; high bone turnover confirmed by kinetic studies carried out with radiocalcium or 99mTc-MDP. An etiological classification of the osteomalacias includes: 1) nutritional osteomalacia: a) inadequate exposure to sunlight and/or insufficient vitamin D intake; b) defective intestinal absorption of vitamin D because of malabsorption syndromes (e.g. jejuno-ileal bypass for obesity).(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:The osteomalacias. 166 41

Serum osteocalcin and alkaline phosphatase levels, as indexes of bone formation, and urinary calcium and hydroxyproline excretions relative to creatinine, as indexes of bone resorption, were measured in 10 obese women before and after two months of hypocaloric diet. In basal condition, serum osteocalcin, but not alkaline phosphatase levels, were higher in obese than in controls (7 +/- 0.4 vs 5.3 +/- 0.2 ng/ml). Urinary calcium/creatinine and hydroxyproline/creatinine ratios were also significantly higher than those in normals (0.37 +/- 0.05 vs 0.2 +/- 0.01 and 0.035 +/- 0.004 vs 0.02 +/- 0.002, respectively). After weight loss, serum osteocalcin significantly increased (9.5 +/- 0.5 ng/ml), while urinary calcium/creatinine and hydroxyproline/creatinine ratios fell to the normal values (0.23 +/- 0.03 and 0.026 +/- 0.001). In conclusion, it appears that obesity, at least in young women, is associated with a high bone turnover, which seems to be reversible with weight loss.
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PMID:[Assessment of bone resorption/neoformation indexes in obese women before and after weight loss]. 209 52

This study was undertaken to evaluate the effect of obesity on the postmenopausal bone mass. Bone mineral density, measured by dual photon absorptiometry of the lumbar spine, serum osteocalcin (OC), fasting urinary calcium to creatinine (Ca:Cr), serum estradiol (E2) dehydroepiandrosterone (DHA) and testosterone (T) were measured in 176 women aged 45-71 years. Women were divided into four groups according to their menopausal status and their weight: 49 perimenopausal, 28 obese perimenopausal, 49 obese postmenopausal. Within each population (perimenopausal and postmenopausal), mean age was the same, only weight was significantly different (p less than 0.0001). For the two groups of postmenopausal women mean interval since menopause (YSM) was the same (5.8 +/- 3 and 5.4 +/- 5 yr). Comparison between groups revealed a significant effect of menopausal status and obesity on BMD and bone turnover. As compared to perimenopausal women, BMD was lower, OC and Ca: Cr higher only in nonobese-postmenopausal women. E2, T, DHA did not differ between the two groups of postmenopausal women. The results of this study suggest that even moderate obesity can play a protective role on postmenopausal bone loss.
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PMID:Obesity and postmenopausal bone loss: the influence of obesity on vertebral density and bone turnover in postmenopausal women. 296 34

In epidemiology of osteoporosis, obesity is to be considered one of its protecting factors. However there are in the literature discordant opinions: some authors describe a protective effect of obesity on the trabecular bone, others on the cortical one, others no effects at all and others finally a positive influence on both the trabecular and the cortical bone. However, only few studies on obesity's impact on bone metabolism are available. Bone mineral density at forearm and serum osteocalcin levels, a specific and sensitive marker of bone turn-over, in a group of postmenopausal obese women with those of a nonobese control group were compared. Obese women showed higher densitometric measurements than nonobese, but only the values of the third distal site of forearm resulted higher in a significant way. Serum osteocalcin values were similar between the two groups but the obese women showed a greater dispersion of the values (8.15 +/- 4.96 ng/ml) compared to nonobese (8.35 +/- 1.63 ng/ml). This high variability suggests an heterogeneity of bone turn-over in obese subjects and could explain the discordant results of the literature.
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PMID:Serum osteocalcin levels in postmenopausal obese women. 917 3

Human and some other primates are unique since their adrenals secrete large amounts of dehydroepiandrosterone (DHEA) and its sulfate (DHEA-S), which are converted into androstenedione (4-dione) and then into potent androgens and estrogens in peripheral tissues, therefore providing autonomous intracrine control to target tissues that can adjust the formation and metabolism of active sex steroids according to local requirements. Knowledge in this area has recently made rapid progress with the elucidation of the structure of most of the tissue-specific cDNAs and genes that encode the steroidogenic enzymes responsible for the transformation of these inactive precursor steroids into androgens and/or estrogens. It is estimated that 30 to 50% of total androgens in men are synthesized in peripheral intracrine tissues from inactive adrenal precursors while, in women, peripheral estrogen formation is even more important, the best estimate being 75% before menopause and 100% after menopause. The marked reduction in the formation of DHEA-S by the adrenals during aging, especially before the age of 50 years, results in a dramatic fall in the formation of active sex steroids in peripheral target tissues, a situation which is thought to be associated with a long series of age-related decreases such as insulin resistance, obesity, osteoporosis, cardiovascular diseases, loss of muscle mass, cancer and other diseases. We have demonstrated for the first time a series of medically important beneficial effects of DHEA administered for 12 months to post-menopausal women. Most interestingly, the bone mineral density significantly increased. This relatively rapid change was associated with an increase in plasma osteocalcin, a marker of bone formation, while a decrease in bone resorption reflected by a decrease in urinary hydroxyproline excretion was observed in parallel. In addition, the estrogenic stimulation of vaginal cytology in the absence of any sign of stimulatory effect on the endometrium is also of potentially major interest for the prevention and management of menopause. Furthermore, the inhibitory effect of DHEA on the growth of human breast cancer xenografts in vivo in nude mice supports the beneficial use of DHEA as hormone replacement therapy in women.
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PMID:DHEA and the intracrine formation of androgens and estrogens in peripheral target tissues: its role during aging. 961 95

After the menopause it has been noted that heavier women conserve bone better than those with lower body weight. The protective effect of obesity on bone mass has been ascribed to a high body fat content. The present study of 54 postmenopausal women was undertaken to determine whether circulating plasma levels of leptin, the newly described hormone produced in adipocytes, were correlated with age-adjusted total body bone mineral content (BMC) or bone mineral density (BMD), or with dynamic biochemical markers of bone resorption or of bone formation. Leptin values were strongly correlated with all measures of adiposity (P < 0.001). Age-adjusted values for BMC and BMD, respectively, were also positively correlated (P < 0.001) with body weight (r = 0.643, r = 0.502), total fat mass (r = 0.557, r = 0.510) and with plasma leptin concentrations (r = 0.480, r = 0.551), confirming a positive relationship between fat mass and bone mass. By contrast, no significant correlations were observed between plasma leptin and dynamic markers of bone resorption (urinary deoxypyridinoline/creatinine r = -0.105, hydroxyproline/creatinine r = -0.193) or formation (plasma osteocalcin r = 0.103). Because there was no evidence for an association between ciculating plasma levels of leptin and biochemical markers of either osteoclastic or osteoblastic activity we conclude it is unlikely that circulating leptin plays any significant direct role in controlling bone cell activity. Our results do not support the hypothesis that leptin mediates the bone-sparing effects of obesity.
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PMID:Plasma leptin values in relation to bone mass and density and to dynamic biochemical markers of bone resorption and formation in postmenopausal women. 981 37

Both bone mass and serum leptin levels are increased in obesity. Because osteoblasts and adipocytes arise from a common precursor in bone marrow, we assessed the effects of human recombinant leptin on a conditionally immortalized human marrow stromal cell line, hMS2-12, with the potential to differentiate to either the osteoblast or adipocyte phenotypes. By RT-PCR and Western immunoblot analysis, the hMS2-12 cells expressed messenger RNA (mRNA) and protein for the leptin receptor. Leptin did not affect hMS2-12 cell proliferation, but resulted in dose- and time-dependent increases in mRNA and protein levels of alkaline phosphatase, type I collagen, and osteocalcin, and in a 59% increase in mineralized matrix. Leptin increased mRNA levels of lipoprotein lipase at 3 days, but decreased mRNA levels of adipsin and leptin at 9 days and decreased lipid droplet formation by 50%. Leptin did not affect the expression of Cbfa1 or peroxisome proliferator-activated receptor-gamma2, transcription factors involved in commitment to the osteoblast and adipocyte pathways, respectively. Thus, leptin acts on human marrow stromal cells to enhance osteoblast differentiation and to inhibit adipocyte differentiation. Our data support the hypothesis that leptin is a previously unrecognized, physiological regulator of these two differentiation pathways, acting primarily on maturation of stromal cells into both lineages.
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PMID:Leptin acts on human marrow stromal cells to enhance differentiation to osteoblasts and to inhibit differentiation to adipocytes. 1009 97

There are several metabolic and hormonal disturbances in childhood obesity. The purpose of this study was to determine the relationship between childhood obesity and bone mineral density (BMD). We studied BMD in 37 obese children and in 37 non-obese children. BMD was measured at L2-L4 level by using dual energy X-ray absorptiometry. BMD was significantly related to age, height and weight. The mean BMD in the obese children and control group was 0.655 +/- 0.175 and 0.626 +/- 0.159 g/cm2, respectively, without any statistically significant difference (p>0.05). There was no correlation between BMD values and osteocalcin or calcitonin levels. According to Tanner's pubertal staging, the mean BMD of pubertal obese children was higher than that of prepubertal obese children. BMD of the pubertal obese children was significantly higher than that of the pubertal control group (p<0.05). Girls had higher mean BMD values than boys. In conclusion, our results show that BMD is not influenced by obesity in children but higher values in puberty were observed in obese children which may due to hormonal changes.
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PMID:Bone mineral density in childhood obesity. 1071 57

The adipocyte-derived hormone leptin, which plays an important role in energy homeostasis, has been suggested to have an influence on bone development and remodeling. However, it is not clear from animal studies whether leptin is a stimulator or an inhibitor of bone growth. Cross-sectional studies in humans suggest that serum leptin levels are positively associated with bone mineral density (BMD), but these observations are not consistent, and whether this relationship is independent of obesity remains unclear. We therefore examined the effect of sc leptin administration on BMD and markers of bone turnover in two women, one with congenital generalized lipodystrophy and the other with acquired generalized lipodystrophy. Both patients had regular menstrual cycles. At baseline, the BMD for both patients, measured at the lumbar spine and total hip, was within 1 SD of the peak bone mass. There was no significant change in BMD in both patients after 16-18 months of leptin therapy. Similarly, concentrations of serum osteocalcin and bone-specific alkaline phosphatase or urinary excretion of deoxypyridinoline and N-telopeptides remained unchanged after 6-8 months of leptin therapy, suggesting no effects of leptin on osteoblastic or osteoclastic activity. Our preliminary data suggest that sc leptin replacement in hypoleptinemic patients with generalized lipodystrophy has no effect on the mature adult skeleton.
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PMID:Effect of subcutaneous leptin replacement therapy on bone metabolism in patients with generalized lipodystrophy. 1241 54

Bone turnover in neonates appears independently of the comparably low maternal bone turnover, but there is only sparse information on the effect of the in utero environment on fetal bone turnover. Postnatally, the resuming growth velocity and alterations in mineral homeostasis affect neonatal bone turnover. This study evaluated the relationship of bone marker concentrations to maternal and fetal auxological variables as well as maternal smoking and assessed the short-term change in bone markers during the first days of life. Serum markers of bone formation [osteocalcin and bone-specific alkaline phosphatase (BALP)] and bone resorption (C-terminal telopeptide of type I collagen) were measured in cord blood and at discharge (median d 3) in 69 healthy term neonates. Concentrations of BALP were significantly lower in neonates of smokers (n = 16) compared with nonsmokers (n = 53), both at birth (p = 0.013) and at discharge (p = 0.036). Both cord osteocalcin and BALP were negatively related to maternal weight and maternal body mass index. Maternal smoking and pregnancy weight gain were the predictors of cord BALP (r2 = 0.24; p < 0.001), whereas the mode of delivery best predicted cord C-terminal telopeptide of type I collagen levels (r2 = 0.19; p < 0.001). C-terminal telopeptide of type I collagen and osteocalcin increased significantly (p < 0.001) from birth to discharge, whereas BALP levels did not change significantly during the same period. Our results suggest that maternal smoking during pregnancy and maternal obesity may have a negative impact on fetal bone formation. The significant increase of osteocalcin and C-terminal telopeptide of type I collagen may result either from an increase in bone turnover or altered renal clearance.
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PMID:Perinatal bone turnover in term human neonates and the influence of maternal smoking. 1262 Nov 14


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