Bone mineral density is inversely related to parathyroid hormone in adolescent girls.

Preventive programs aimed at maximizing peak bone mass as a way of reducing the risk of osteoporotic fractures later in life should take into account the contribution of nutritional factors to bone mass accumulation in young age. The role of calcium and energy intakes on radial mineral density was investigated in 200 healthy girls (aged 11-15 yr) simultaneously evaluating serum changes of insulin-like growth factor-I (IGF-I), parathyroid hormone (PTH) and osteocalcin (OC). Dietary calcium and energy intakes were assessed by a 3-day food record method, bone mineral density (BMD) was performed at ultradistal (ud) and proximal (pr) radial sites using dual energy X-ray absorptiometry. Calcium consumption below the levels suggested by Dietary Reference Intakes in more than 80% of population studied was not related to BMD, which in turn markedly increased in post-compared to premenarcheal girls. Interestingly, in a multiple regression analysis PTH was inversely related to BMD after adjustment for calcium intake, bone age and menarche. Serum IGF-I was positively associated to energy intakes and bone age in girls before menarche, who exhibited the highest values of OC. Our data highlighted the role of food habits in modulating some hormonal response that might influence bone mineral apposition during adolescent age. Low calcium consumption associated to enhanced PTH values, if persisting, could be responsible for reduced rate of gain in bone mineral density. Thus, to optimize bone mineralization during the critical period of rapid body growth adequate intakes of calcium and energy should be recommended.     

Are bone and muscle changes from POWER PE, an 8-month in-school jumping intervention, maintained at three years?

Our aim was to determine if the musculoskeletal benefits of a twice-weekly, school-based, jumping regime in healthy adolescent boys and girls were maintained three years later. Subjects of the original POWER PE trial (n = 99) were contacted and asked to undergo retesting three years after cessation of the intervention. All original measures were completed including: sitting height, standing height, weight, calcaneal broadband ultrasound attenuation (BUA), whole body, hip and spine bone mineral content (BMC), lean tissue mass, and fat mass. Physical activity was recorded with the bone-specific physical activity questionnaire (BPAQ) and calcium intake was estimated with a calcium-focussed food questionnaire. Maturity was determined by Tanner staging and estimation of the age of peak height velocity (PHV). Twenty-nine adolescents aged 17.3 ± 0.4 years agreed to participate. Three years after the intervention, there were no differences in subject characteristics between control and intervention groups (p>0.05). Three-year change in weight, lean mass, and fat mass were similar between groups (p>0.05). There were no significant group differences in three-year change in BUA or BMC at any site (p>0.05), although the between-group difference in femoral neck BMC at follow-up exceeded the least significant change. While significant group differences were not observed three years after cessation of the intervention, changes in bone parameters occurred in parallel for intervention and control groups such that the original benefits of the intervention observed within the treatment group were sustained.     

Protein-containing nutrient supplementation following strength training enhances the effect on muscle mass, strength, and bone formation in postmenopausal women.

We evaluated the response of various muscle and bone adaptation parameters with 24 wk of strength training in healthy, early postmenopausal women when a nutrient supplement (protein, carbohydrate, calcium, and vitamin D) or a placebo supplement (a minimum of energy) was ingested immediately following each training session. At inclusion, each woman was randomly and double-blindedly assigned to a nutrient group or a placebo (control) group. Muscle hypertrophy was evaluated from biopsies, MRI, and dual-energy X-ray absorptiometry (DEXA) scans, and muscle strength was determined in a dynamometer. Bone mineral density (BMD) was measured using DEXA scans, and bone turnover was determined from serum osteocalcin and collagen type I cross-linked carboxyl terminal peptide. The nutrient group improved concentric and isokinetic (60 degrees /s) muscle strength from 6 to 24 wk by 9 +/- 3% (P < 0.01), whereas controls showed no change (1 +/- 2%, P > 0.05). Only the nutrient group improved lean body mass (P < 0.05) over the 24 wk. BMD responded similarly at the lumbar spine but changed differently in the two groups at the femoral neck (P < 0.05) [control: 0.943 +/- 0.028 to 0.930 +/- 0.024 g/mm(3) (-1.0 +/- 1.4%); nutrient group: 0.953 +/- 0.051 to 0.978 +/- 0.043 g/mm(3) (3.8 +/- 3.4%)] when adjusted for age, body mass index, and BMD at inclusion. Bone formation displayed an interaction (P < 0.05), mainly caused by increased osteocalcin at 24 wk in the nutrient group. In conclusion, we report that nutrient supplementation results in superior improvements in muscle mass, muscle strength, femoral neck BMD, and bone formation during 24 wk of strength training. The observed differences following such a short intervention emphasize the significance of postexercise nutrient supply on musculoskeletal maintenance.     

Food restriction suppresses muscle growth and augments osteopenia in ovariectomized rats.

We examined effects of 4 wk of food restriction on ovariectomy-related changes in muscle, bone, and plasma insulin-like growth factor I (IGF-I). Female Sprague-Dawley rats (7 mo old) were assigned to freely eating groups: sham-operated (Sham), ovariectomized (Ovx-AL), and estrogen (estradiol)-replaced Ovx (Ovx+E(2)). Ovx rats were also pair fed with Sham (Ovx-PF) or weight matched with Sham by food restriction (Ovx-FR). Ovx-AL and Ovx-PF rats had similar estrogen status and body weight; therefore, the groups were combined (group: Ovx). After treatment, body weight was approximately 10% greater in Ovx than in Sham rats (P < 0.05), and muscle weight-to-body weight ratios were comparable among all groups. Bone mineral contents of whole tibiae in Ovx-FR and Ovx were approximately 15% (P < 0.05) and approximately 6% lower than in Sham rats (P < 0.05), respectively. Plasma IGF-I was approximately 30% higher in Ovx than in Sham (P < 0.05) but was similar between Sham and Ovx-FR. IGF-I was highly correlated with body weight and muscle mass. Within non-estrogen-replaced Ovx rats, IGF-I explained approximately 19% of variance in bone mineral content after accounting for variance attributable to body weight. Findings suggest that estrogen acts indirectly on skeletal muscle and bone in rats through regulation of body growth by factors such as IGF-I.     

Vitamin-D receptor genotype does not predict bone mineral density, bone turnover, and growth in prepubertal children.

We examined whether the polymorphism for BsmI restriction enzyme in the vitamin-D receptor (VDR) gene influenced radial (distal third) and lumbar (L2-L4) bone mineral density (BMD), phospho-calcium metabolism (calcium, phosphate, intact parathyroid hormone, 25-hydroxyvitamin D, and 1,25-dihydroxyvitamin D), biochemical markers of bone formation (osteocalcin and carboxy-terminal propeptide of type-I procollagen) and bone resorption (carboxy-terminal telopeptide of type-I collagen and urinary cross-linked N-telopeptides of type I collagen), insulin-like growth factor I and insulin-like growth factor-binding protein 3, and growth in 209 healthy prepubertal children (112 males and 97 females) aged 7.1-10.0 years. Genotype frequencies were BB 19%, Bb 46%, and bb 35% in the pooled group of children. Clinical findings, dietary calcium intake, calcium density, and physical activity rate were not different (p NS) among the VDR genotypes. Radial BMD, lumbar BMDarea and lumbar BMD adjusted for the apparent bone volume (BMDvolume), and all the biochemical parameters did not differ (p NS) in relation to the VDR genotype. In conclusion, our data show that polymorphism for BsmI restriction enzyme in the VDR gene is not associated with radial and lumbar BMD, parameters of phospho-calcium metabolism and bone turnover, growth hormone-dependent growth factors, and growth in prepubertal children.     

Effects of lycopene supplementation in patients with localized prostate cancer

Epidemiological studies have shown an inverse association between dietary intake of lycopene and prostate cancer risk. We conducted a clinical trial to investigate the biological and clinical effects of lycopene supplementation in patients with localized prostate cancer. Twenty-six men with newly diagnosed prostate cancer were randomly assigned to receive a tomato oleoresin extract containing 30 mg of lycopene (n = 15) or no supplementation (n = 11) for 3 weeks before radical prostatectomy. Biomarkers of cell proliferation and apoptosis were assessed by Western blot analysis in benign and cancerous prostate tissues. Oxidative stress was assessed by measuring the peripheral blood lymphocyte DNA oxidation product 5-hydroxymethyl-deoxyuridine (5-OH-mdU). Usual dietary intake of nutrients was assessed by a food frequency questionnaire at baseline. Prostatectomy specimens were evaluated for pathologic stage, Gleason score, volume of cancer, and extent of high-grade prostatic intraepithelial neoplasia. Plasma levels of lycopene, insulin-like growth factor-1, insulin-like growth factor binding protein-3, and prostate-specific antigen were measured at baseline and after 3 weeks of supplementation or observation. After intervention, subjects in the intervention group had smaller tumors (80% vs 45%, less than 4 ml), less involvement of surgical margins and/or extra-prostatic tissues with cancer (73% vs 18%, organ-confined disease), and less diffuse involvement of the prostate by high-grade prostatic intraepithelial neoplasia (33% vs 0%, focal involvement) compared with subjects in the control group. Mean plasma prostate-specific antigen levels were lower in the intervention group compared with the control group. This pilot study suggests that lycopene may have beneficial effects in prostate cancer. Larger clinical trials are warranted to investigate the potential preventive and/or therapeutic role of lycopene in prostate cancer.     

Natural bovine osteogenin and recombinant human bone morphogenetic protein-2B are equipotent in the maintenance of proteoglycans in bovine articular cartilage explant cultures.

Osteogenin and related bone morphogenetic proteins are members of the transforming growth factor-beta superfamily, and were isolated by their ability to induce cartilage and bone formation in vivo. The influence of osteogenin, purified from bovine bone, and of recombinant human bone morphogenetic protein-2B (BMP-2B) has been examined in bovine articular cartilage explants. Both differentiation factors stimulated in a dose-dependent manner the synthesis of proteoglycans and decreased their rate of degradation. At a dose of 30 ng/ml, proteoglycan synthesis was increased to levels observed with either 20 ng/ml insulin-like growth factor I, 10 ng/ml transforming growth factor-beta, or 20% fetal bovine serum. This increase of biosynthetic rates above basal medium levels was observed in young, adolescent, and adult tissues. Analysis of the size of the newly synthesized proteoglycans, the glycosaminoglycan chain size, and the glycosaminoglycan type of explants treated with osteogenin or BMP-2B were very comparable to each other, and to proteoglycans isolated from cartilage treated with either insulin-like growth factor I or fetal bovine serum. These results demonstrate that osteogenin and BMP-2B alone are capable of stimulating and maintaining the chondrocyte phenotype in vitro.     

Skeletal mass in adolescent male athletes and nonathletes: relationships with high-impact sports

Dias Quiterio, AL, Canero, EA, Baptista, FM, and Sardinha, LB. Skeletal mass in adolescent male athletes and nonathletes: relationships with high-impact sports. J Strength Cond Res 25(12): 3439-3447, 2011-This study examined the relationships between the practice of different categories of sports (high-impact vs. nonimpact) and bone status in adolescent male athletes and investigated differences from an age-matched control group. A total of 54 adolescent male athletes and 26 adolescent nonathletes were evaluated. Bone mineral density, bone mineral content (BMC), and bone area at the whole-body, limbs, and lumbar spine were determined by dual-energy x-ray absorptiometry, along with total and regional fat-free mass and body fat. The high-impact group included 34 athletes: 9 gymnasts, 18 basketball players, and 7 handball players (age: 15.7 ± 1.6 years; weight: 72.0 ± 15.0 kg; height: 178.5 ± 12.5 cm). The nonimpact group consisted of 20 swimmers (age: 16.4 ± 2.5 years; weight: 66.9 ± 10.4 kg; height: 173.7 ± 10.9 cm). The nonathletic control group included 26 male adolescents (age: 15.9 ± 2.8 years; weight: 64.7 ± 16.3 kg; height: 168.6 ± 15.1 cm). No differences were observed between the nonimpact and the control group in all bone variables, before and after adjustments for maturation level, body weight, and height (p > 0.05). After adjustments for these variables, the high-impact group displayed greater bone mass in most of the measured sites when compared to the other 2 groups (p < 0.001). Subjects in the nonimpact group showed lower values of BMC, particularly in the lower limbs, than both the high-impact and the nonathletic control groups (p < 0.05) after adjustments for maturation, high, and fat-free mass. This study reinforces the positive associations between high-impact physical activities and skeletal health in adolescent boys.     

Gender differences in regional body composition and somatotrophic influences of IGF-I and leptin.

This study evaluated the arm, trunk, and leg for fat mass, lean soft tissue mass, and bone mineral content (BMC) assessed via dual-energy X-ray absorptiometry in a group of age-matched (approximately 29 yr) men (n = 57) and women (n = 63) and determined their relationship to insulin-like growth factor I (IGF-I) and leptin. After analysis of covariance adjustment to control for differences in body mass between genders, the differences that persisted (P < or = 0.05) were for lean soft tissue mass of the arm (men: 7.1 kg vs. women: 6.4 kg) and fat mass of the leg (men: 5.3 kg vs. women: 6.8 kg). Men and women had similar (P > or = 0.05) values for fat mass of the arms and trunk and lean soft tissue mass of the legs and trunk. Serum IGF-I and insulin-like growth factor binding protein-3 correlated (P < or = 0.05) with all measures of BMC (r values ranged from 0.31 to 0.39) and some measures of lean soft tissue mass for women (r = 0.30) but not men. Leptin correlated (P < or = 0.05) similarly for measures of fat mass for both genders (r values ranging from 0.74 to 0.85) and for lean soft tissue mass of the trunk (r = 0.40) and total body (r = 0.32) for men and for the arms in women (r = 0.56). These data demonstrate that 1) the main phenotypic gender differences in body composition are that men have more of their muscle mass in their arms and women have more of their fat mass in their legs and 2) gender differences exist in the relationship between somatotrophic hormones and lean soft tissue mass.     

Bone and Gastric Bypass Surgery: Effects of Dietary Calcium and Vitamin D

Objective:To examine bone mass and metabolism in women who had previously undergone Roux‐en‐Y gastric bypass (RYGB) and determine the effect of supplementation with calcium (Ca) and vitamin D. Research Methods and Procedures: Bone mineral density and bone mineral content (BMC) were examined in 44 RYGB women (≥3 years post‐surgery; 31% weight loss; BMI, 34 kg/m²) and compared with age‐ and weight‐matched control (CNT) women (n = 65). In a separate analysis, RYGB women who presented with low bone mass (n = 13) were supplemented to a total 1.2 g Ca/d and 8 μg vitamin D/d over 6 months and compared with an unsupplemented CNT group (n = 13). Bone mass and turnover and serum parathyroid hormone (PTH) and 25‐hydroxyvitamin D were measured. Results:Bone mass did not differ between premenopausal RYGB and CNT women (42 ± 5 years), whereas postmenopausal RYGB women (55 ± 7 years) had higher bone mineral density and BMC at the lumbar spine and lower BMC at the femoral neck. Before and after dietary supplementation, bone mass was similar, and serum PTH and markers of bone resorption were higher (p < 0.001) in RYGB compared with CNT women and did not change significantly after supplementation. Discussion: Postmenopausal RYGB women show evidence of secondary hyperparathyroidism, elevated bone resorption, and patterns of bone loss (reduced femoral neck and higher lumbar spine) similar to other subjects with hyperparathyroidism. Although a modest increase in Ca or vitamin D does not suppress PTH or bone resorption, it is possible that greater dietary supplementation may be beneficial.     

Effects of serum irisin,neuregulin 4, and weight management on obese adolescent girls with polycystic ovary syndrome

The study is aimed at investigating the association of serum irisin, neuregulin 4 (NRG4), and anti-müllerian hormone (AMH) with adolescent obesity with polycystic ovary syndrome (PCOS) and the efficacy of weight management interventions. Serum levels of irisin, NRG4, AMH, sex steroid hormone, body mass index (BMI), serum insulin, and C-peptide were measured in 52 obese adolescent girls with PCOS (PCOS group) and 43 obese adolescent girls without PCOS (non-PCOS group). The levels of AMH, NRG4, serum irisin, sex steroid hormones, BMI, serum insulin, and C-peptide were evaluated in obese PCOS girls before and after one year weight management. The levels of AMH, serum insulin, NRG4, and total testosterone of PCOS group were significantly higher than those of non-PCOS group. On the contrary, serum irisin and serum C-peptide in PCOS group were significantly lower than that in non-PCOS group. The levels of fat mass, percent body fat, total testosterone, AMH, NRG4, and serum insulin in the obese girls with PCOS showed significant decreases compared with before weight management intervention. On the contrary, after one year of body weight management intervention, serum irisin and serum C-peptide was significantly increased. Adolescent obesity complicated with PCOS is significantly associated with glucose and lipid metabolism and sex steroid hormone disorders, but the exact pathophysiological and clinical features are highly variable. Weight management intervention can significantly improve the clinical symptoms and hematological indicators, serum irisin and NRG4 can be used as two essential biomarkers for evaluating weight management.     

Relationships of dietary fat, body composition, and bone mineral density in inbred mouse strain panels.

Laboratory inbred mouse strains show a broad range of variation in phenotypes, such as body composition, bone mineral density (BMD), plasma leptin, and insulin-like growth factor I (IGF-I), and thus provide a basis for the study of associations among them. We analyzed these phenotypes in male and female mice from 43 inbred strains fed on a high-fat (30% caloric content) diet and from 30 inbred strains fed on a low-fat (6%) diet. Structural equation modeling of these data reveals that the relationship of body fat content and areal BMD is altered by dietary factors and genotypes. Sex has no net effect on areal BMD, but after accounting for body mass difference females have higher areal BMD. Leptin is affected by relative fat mass and has no net effect on areal BMD. IGF-I has a direct effect on areal BMD.     

Role of peak bone mass and bone loss in postmenopausal osteoporosis: 12 year study.

OBJECTIVE--To examine the role of peak bone mass and subsequent postmenopausal bone loss in the development of osteoporosis and the reliability of identifying women at risk from one bone mass measurement and one biochemical assessment of the future bone loss. DESIGN--Population based study. SETTING--Outpatient clinic for research into osteoporosis. SUBJECTS--178 healthy early postmenopausal women who had participated in a two year study in 1977. 154 of the women underwent follow up examination in 1989, of whom 33 were excluded because of diseases or taking drugs known to affect calcium metabolism. MAIN OUTCOME MEASURES--Bone mineral content of the forearm and values of biochemical markers of bone turnover. RESULTS--The average reduction in bone mineral content during 1977-89 was 20%, but the fast losers had lost 10.0% more than had the slow loser group (mean loss 26.6% in fast losers and 16.6% in slow losers; p less than 0.001). Prediction of future bone mineral content using baseline bone mineral content and estimated rate of loss gave results almost identical with the actual bone mineral content measured in 1989. Seven women had had a Colles'' fracture and 20 a spinal compression fracture. The group with Colles'' fracture had low baseline bone mineral content (34.7 (95% confidence interval 31.3 to 38.1) units v 39.4 (38.1 to 40.8) units in women with no fracture) whereas the group with spinal fracture had a normal baseline bone mineral content (38.1 (35.0 to 41.1) units) but an increased rate of loss (-2.4 (-3.5 to -1.3)%/year v -1.8 (-2.1 to -1.5)%/year in women with no fracture). CONCLUSIONS--One baseline measurement of bone mass combined with a single estimation of the rate of bone loss can reliably identify the women at menopause who are at highest risk of developing osteoporosis later in life. The rate of loss may have an independent role in likelihood of vertebral fracture.     

Growth hormone and bone health

Growth hormone (GH) and insulin-like growth factor-I have major effects on growth plate chondrocytes and all bone cells. Untreated childhood-onset GH deficiency (GHD) markedly impairs linear growth as well as three-dimensional bone size. Adult peak bone mass is therefore about 50% that of adults with normal height. This is mainly an effect on bone volume, whereas true bone mineral density (BMD; g/cm(3)) is virtually normal, as demonstrated in a large cohort of untreated Russian adults with childhood-onset GHD. The prevalence of fractures in these untreated childhood-onset GHD adults was, however, markedly and significantly increased in comparison with normal Russian adults. This clearly indicates that bone mass and bone size matter more than true bone density. Adequate treatment with GH can largely correct bone size and in several studies also bone mass, but it usually requires more than 5 years of continuous treatment. Adult-onset GHD decreases bone turnover and results in a mild deficit, generally between -0.5 and -1.0 z-score, in bone mineral content and BMD of the lumbar spine, radius and femoral neck. Cross-sectional surveys and the KIMS data suggest an increased incidence of fractures. GH replacement therapy increases bone turnover. The three controlled studies with follow-up periods of 18 and 24 months demonstrated a modest increase in BMD of the lumbar spine and femoral neck in male adults with adult-onset GHD, whereas no significant changes in BMD were observed in women. GHD, whether childhood- or adult-onset, impairs bone mass and strength. Appropriate substitution therapy can largely correct these deficiencies if given over a prolonged period. GH therapy for other bone disorders not associated with primary GHD needs further study but may well be beneficial because of its positive effects on the bone remodelling cycle.     

The influence of bariatric surgery on calcium homeostasis and biochemical markers of bone turnover in patients with morbid obesity

INTRODUCTION: Obese patients may have abnormal calcium homeostasis because of unbalanced diet and decreased sun exposure. Bariatric surgery itself may lead to disturbances in calcium homeostasis (and in consequence changes in bone mass) or increase preexisting metabolic derangements. The aim of the study was: 1. To assess calcium homeostasis and biochemical markers of bone turnover in patients with morbid obesity. 2. To determine the impact of bariatric surgery on parameters mentioned above. 3. To establish recommendations for supplementation with calcium and vitamin D in morbidly obese patients after bariatric surgery. MATERIAL AND METHODS: Serum calcium, parathormone (PTH), vitamin D (25(OH)D), biochemical markers of bone turnover (beta-CrossLaps as a marker of bone resorption and osteocalcin as a marker of bone formation) and urine calcium as well as fat mass, lean mass and bone mineral content (by DXA) were measured before bariatric surgery of the stomach (VBG or GBP) in 57 morbidly obese patients (48 women, 9 men; mean age 35.9 y). The same procedures were repeated six months after operation in 28 of them (24 women, 4 men). Daily calcium intake was also determined based on food questionnaire. RESULTS: Biochemical findings in the group of patients before bariatric surgery were as follows: serum calcium, beta-CrossLaps and urine calcium were within normal range, PTH concentration was increased to 81.0 pg/ml and 25(OH)D as well as osteocalcin concentration decreased (4.9 ng/ml and 13.6 ng/ml, respectively). Six months after bariatric surgery there was no change in serum and urine calcium, PTH concentration decreased to normal level (46.8 pg/ml), 25(OH)D concentration increased to 6.5 ng/ml (not significant) and still remained below normal range. Markers of bone turnover--both resorption and formation--increased (beta-CrossLaps over normal range to 0.594 ng/ml, osteocalcin to normal range 26.8 ng/ml). Daily calcium intake was below RDA before and after bariatric procedure. CONCLUSIONS: 1. Patients with morbid obesity have secondary hyperparathyroidism and deficiency of vitamin D. 2. Abrupt weight loss after bariatric surgery is accompanied by the regression of secondary hyperparathyroidism, decrease of the deficiency of vitamin D and increase in bone turnover. 3. Supplementation with vitamin D and calcium is recommended for patients with morbid obesity after bariatric surgery.     

Vitamin D-deficiency in Asia

Vitamin D-deficiency rickets is an important disease of childhood in China. It occurs in all regions (20-53 degrees N) but is more prevalent in the north. A survey in Beijing indicated that Vitamin D-deficiency (plasma 25(OH)D concentration <12.5 nmol/l) occurred in more than 40% of adolescent girls in winter. Dietary calcium was often as low as 350 mg per day and a positive correlation was found between this and both bone mineral density (BMD) and Vitamin D status. In a subsequent intervention study with 757 Beijing schoolgirls, a daily supplement of milk, fortified with calcium, was provided on school days for 24 months. From anthropometric and bone density data, it is evident that the increased calcium intake from milk, had significant effects on bone and that deficiencies of both calcium and of Vitamin D had been affecting bone growth and development. In neighboring Mongolia (42 degrees -50 degrees N), rickets is also common, but its prevalence has increased since 1990. A 2-year survey (2000-2002) in Mongolia indicated that, as in China, a low intake of calcium and limited exposure to solar ultraviolet (UV) light in summer were associated with Vitamin D-deficiency. However, over the last decade, malnutrition has become widespread. It now appears that malnutrition impairs the efficiency of the utilization of Vitamin D obtained in summer. Hence, a number of factors need to be addressed to prevent Vitamin D-deficiency during growth.     

Association of pharmacological tests and study of 24-hour growth hormone secretion in the investigation of growth retardation in children: analysis of 257 cases

Growth hormone (GH) secretion can presently be investigated by several methods: pharmacological provocative tests, study of 24-h GH secretion, measurement of somatomedin-C (Sm-C)/insulin-like growth factor (IGF) I, and the growth hormone-releasing hormone (GHRH) test. In order to compare the results obtained, these methods were used in 257 children with growth retardation (169 boys, 88 girls). Their height SD was -2.7 +/- 0.2, chronological age 11 3/12 +/- 1 6/12 years, and bone age 8 4/12 +/- 1 4/12 years. Mean growth velocity was 4.5 +/- 1.5 cm/year. One hundred and thirty-eight boys and 80 girls were prepubertal, and 31 boys and 8 girls were pubertal (B2 G2). All children underwent the study of 24-h GH secretion (n = 257) and pharmacological provocative tests (two tests, n = 213; one test n = 44). Sm-C/IGF I was measured in prepubertal children (n = 131), and a GHRH test was carried out (n = 153). In addition, the mean integrated concentration of growth hormone secretion (IC-GH) was assessed in a control group of 23 children and was found to be 5.4 +/- 1.2 ng/ml/min. The IC-GH in the group as a whole was 2.6 ng/ml/min. The mean maximum peak during pharmacological tests varied considerably according to the test used, ranging from 7.8 ng/ml for the arginine test to 17.1 ng/ml for the glucagon and betaxolol test. The maximum peak and the 24-h IC-GH were not significantly correlated.(ABSTRACT TRUNCATED AT 250 WORDS)     

Body composition in Egyptian Turner syndrome girls

OBJECTIVE:

This cross-sectional study was undertaken to construct the new body fat % curve and provide body composition reference data for adolescent girls with Turner syndrome (TS). They diagnosed cytogenetically by blood karyotyping and not treated with growth hormone (GH).

MATERIALS AND METHODS:

The study included 70 TS girls from age 13 years to age 17 years. Body composition was measured by bioelectrical impedance. Smoothed centile charts were derived by using the least mean square (LMS) method.

RESULTS:

The new body fat curves reflect the increase of body fat mass (FM) from age 13 years to age 17 years. Body FM % of Egyptian TS girls was lower when compared with age-matched American untreated TS girls.

CONCLUSION:

This study presents the new body fat curves and reference values of body composition for untreated Egyptian TS adolescent girls. The present charts can be used for direct assessment of body FM % for Egyptian TS girls and evaluation for cases on GH treatment or other growth promoting therapy.     

啦啦操和健美操训练对改善初中女生体质的效果比较

为了探究啦啦操或健美操训练对初中女生身体成分、骨密度以肌肉爆发力的影响,在严格控制研究对象的纳入标准的情况下,招募参与啦啦操训练的初中女生62人（啦啦操组）,参与健美操训练的初中女生58人（健美操组）,无啦啦操或健美操训练经历的初中女生80人（对照组）,分别测量其身高、体质量、身体成分、相关部位的骨密度和肌肉爆发力,进行比较研究。结果显示,与对照组相比较,啦啦操组和健美操组的蛋白质百分数、肌肉百分数和无机盐百分数都明显较高,而脂肪百分数明显较低;与啦啦操组相比较,健美操组的蛋白质百分数和肌肉百分数明显较高,而脂肪百分数明显较低。与对照组相比较,啦啦操组和健美操组的髋骨骨密度明显较高,健美操组的脊柱骨密度也明显较高;与啦啦操组相比较,健美操组的髋骨骨密度也明显较高。与对照组相比较,啦啦操组的下肢肌肉爆发力明显较高,健美操组的上肢肌肉、下肢肌肉、腰腹屈肌和腰背伸肌的爆发力也明显较高;与啦啦操组相比较,健美操组的上肢肌肉、下肢肌肉、腰腹屈肌和腰背伸肌的爆发力也明显较高。结果提示啦啦操或健美操训练都能够改善初中女生的身体成分,增加其骨密度和肌肉爆发力,但是健美操的干预效果要优于啦啦操,这可能与健美操的技术特点和运动强度有关。     

The Effects of Mg Supplementation in Diets with Different Calcium Levels on the Bone Status and Bone Metabolism in Growing Female Rats

Previous studies have revealed that magnesium (Mg) plays a significant role in bone health; however, few studies have investigated the effects of Mg supplementation in diets with different calcium (Ca) levels on the bone status and bone metabolism in a growing stage. In this present study, we tested the effects of Mg supplementation on bone status in growing female rats, relative to Ca intake levels. A total of 40 Sprague–Dawley female rats aged 6 weeks were divided into the following four groups and fed for 12 weeks as indicated: (1) LCaAMg: low Ca (Ca, 0.1 % of total diet) and adequate Mg (Mg, 0.05 % of total diet), (2) LCaHMg: low Ca and high Mg ( Mg, 0.1 % of total diet), (3) ACaAMg: adequate Ca (Ca, 0.5 % of total diet) and adequate Mg, and (4) ACaHMg: adequate Ca and high Mg. Our results showed that Mg supplementation with the adequate Ca diet significantly increased the bone mineral contents, bone size (bone area and bone thickness), and bone mineral density of femur or tibia by improving bone metabolism without changing Ca absorption. Mg supplementation significantly increased the serum osteocalcin in the adequate-Ca-diet group (p?<?0.05), while the Mg supplementation significantly decreased the serum level of C-telopeptide cross-links of type I collagen in the adequate-Ca-diet group (p?<?0.001). This study suggests that Mg supplementation with adequate Ca intake in the growing stage may increase the bone mineral density and bone size by improving bone metabolism.