Zulf Mughal

Identification of 70 calcium-sensing receptor mutations in hyper- and hypo-calcaemic patients: evidence for clustering of extracellular domain mutations at calcium-binding sites

The calcium-sensing receptor (CaSR) is a G-protein-coupled receptor that has an extracellular bilobed venus flytrap domain (VFTD) predicted to contain five calcium (Ca(2+))-binding sites. To elucidate the structure-function relationships of the VFTD, we investigated 294 unrelated probands with familial hypocalciuric hypercalcaemia (FHH), neonatal severe primary hyperparathyroidism (NSHPT) or autosomal dominant hypocalcaemic hypercalciuria (ADHH) for CaSR mutations and performed in vitro functional expression studies and three-dimensional modelling of mutations involving the VFTD. A total of 70 different CaSR mutations were identified: 35 in FHH, 10 in NSHPT and 25 in ADHH patients. Furthermore, a CaSR variant (Glu250Lys) was identified in FHH and ADHH probands and demonstrated to represent a functionally neutral polymorphism. NSHPT was associated with a large proportion of truncating CaSR mutations that occurred in the homozygous or compound heterozygous state. Thirty-four VFTD missense mutations were identified, and 18 mutations were located within 10 Å of one or more of the predicted Ca(2+)-binding sites, particularly at the VFTD cleft, which is the principal site of Ca(2+) binding. Mutations of residues 173 and 221, which are located at the entrance to the VFTD cleft binding site, were associated with both receptor activation (Leu173Phe and Pro221Leu) and inactivation (Leu173Pro and Pro221Gln), thereby highlighting the importance of these residues for entry and binding of Ca(2+) by the CaSR. Thus, these studies of disease-associated CaSR mutations have further elucidated the role of the VFTD cleft region in Ca(2+) binding and the function of the CaSR.

Variation in lumbar spine bone mineral content by age and gender in apparently healthy Indians.

The aim of this study was to assess variation in bone mass from childhood through later age and to examine bone health status of Indian males and females. Lumbar spine (LS) bone mineral content (BMC) was measured by dual energy X-ray absorptiometry of lumbar vertebrae (L1–L4) in 683 males and 858 females (5–70xa0years) from Pune, India and apparent bone mineral density (BMAD) was calculated. A cubic regression model was fitted to describe the change in bone mineral content (BMC) with age in males and females separately. Regression analysis revealed that peak LS BMC was achieved around 26xa0years (63.6xa0±xa011.0xa0g) for males and 30xa0years (54.1xa0±xa011.6xa0g) for females. After 50xa0years of age, BMC showed an average annual decrease of 2.7% in males and 4.1% in females. Males had 11–15% higher mean BMAD than females after 50xa0years of age. T scores of 19% males and 28% females above 50xa0years, were less than −2.5 and T scores of 36% males and 43% females were between −1.0 and −2.5 when compared with the Lunar reference database. Low peak bone mass at a young age and higher bone loss in adults are alarming features of apparently healthy Indians.

Enhanced effect of zinc and calcium supplementation on bone status in growth hormone-deficient children treated with growth hormone: a pilot randomized controlled trial

Reduced bone mineral content in growth hormone-deficient children (GHD) has been reported. Calcium, zinc, and vitamin D play an important role in bone formation. Hence, the aim of this pilot randomized controlled study was to evaluate the effect of calcium, vitamin D, and zinc supplementation in prepubertal GHD children treated with GH on bone health parameters. After 1xa0year of treatment with GH (20xa0mg/m2/week), 31 GHD (mean age 8.7xa0±xa02.8xa0years, 18 boys) prepubertal children were randomised to receive calcium (500xa0mg/day) and vitamin D (60,000xa0IU/3xa0months) [Group A] or a similar supplement of calcium, vitamin D, and zinc (as per Indian Recommended Allowance) [Group B] along with GH therapy for the next 12xa0months. The two groups were similar in anthropometric and body composition parameters at baseline (pxa0>xa00.1). After 1xa0year of GH therapy, height-adjusted % gain was similar in both groups, 48xa0% in bone mineral content (BMC) and 45xa0% in bone area (BA). Height-adjusted % increase in BMC was significantly (pxa0<xa00.05) higher in the second year than in the first in both the groups. This % increase in BMC and BA was greater in Group B (51 and 36xa0% respectively) than in Group A (49 and 34xa0%), although marginally (pxa0<xa00.05). Supplementation of calcium and vitamin D along with GH therapy in GHD Indian children has the potential for enhancing bone mass accrual; this effect was further enhanced through the addition of zinc supplement.

Varying relationship between 25-hydroxy-vitamin D, high density lipoprotein cholesterol, and serum 7-dehydrocholesterol reductase with sunlight exposure.

BACKGROUNDnCholesterol and cholecalciferol are synthesized from a common substrate 7-dehydrocholesterol. 7-dehydrocholesterol is converted to cholesterol by 7-dehydrocholesterol reductase enzyme (DHCR7) and to cholecalciferol by ultraviolet B radiation from sunlight.nnnOBJECTIVEnTo examine the effect of sunlight exposure and serum DHCR7 levels on cholecalciferol and cholesterol levels and studying any interrelationship.nnnMETHODSnIn a cross-sectional observational study, 307 apparently healthy men (aged 40-60 years) were assessed for sunlight exposure, lipid levels, serum DHCR7, 25 hydroxyvitamin D (25(OH)D), body composition, and dietary milk calcium intake.nnnRESULTSnVitamin D deficiency (25(OH)D <20 ng/mL, 1 ng/mL = 2.496 nmols/L) was found in 56% of subjects. Serum 25(OH)D concentrations increased significantly with increasing duration of sunlight exposure (P < .05). At lower sunlight exposure (<1 h/d), serum 25(OH)D levels were positively associated with high-density lipoprotein cholesterol (HDL-C) levels (P < .05) but at moderate sunlight exposure (1-2 h/d), there was no significant association. However, with higher sunlight exposure (>2 h/d), serum 25(OH)D concentrations were significantly negatively associated with HDL-C (P < .05). At moderate and higher sunlight exposure, an inverse significant relationship was observed between 25(OH)D and serum DHCR7 (P < .05); however, at lower sunlight exposure, no significant relationship was seen.nnnCONCLUSIONSn25(OH)D seems to show a varying relationship with HDL-C and serum DHCR7 at different durations of sunlight exposure.

Low bone status in Indian growth hormone-deficient children

Abstract Background: Growth hormone (GH) is critical for linear bone growth, skeletal maturation and mineralization during childhood. Aims: The aim of this study is to examine the impact of bone size and lean body mass (LBM) adjusted less head (LH) total body bone mineral content (TBBMC) in 50 prepubertal GH-deficient children. Results: The mean height (Ht) for age Z-score was –5.0±1.7. The mean total body less head (TBLH) BMC for Ht age Z-score after adjusting for TBLH LBM and TBLH BA was –3.27±0.27. The mean TBLH BMC Z-score remained below –2 even after adjustments for TBLH LBM, bone age, and Ht age, suggesting a deficit of BMC in spite of all adjustments. Applying the Molgaard approach, all children had “short bones,” 86% had “narrow bones,” and 72% had “light bones.” When adjusted for LBM, 87% of the children had low LBM for Ht and 33% had low TBLH BMC for TBLH LBM. Conclusion: LH TBBMC of children remained low, even after adjustment for bone size and LBM.

Changes in body composition of Indian lactating women: a longitudinal study

BACKGROUND AND OBJECTIVESnLactation places enormous demands on maternal bone mineral homeostasis. Indian middle class women (MSC) consume energy dense food supplements to meet these demands post-partum (PP) along with restricted physical activity (PA). Effects of these changes on body composition (BC) of PP women have not been studied. To examine longitudinal changes in: a) bone mineral density (BMD) at total body (TB), AP-spine (APS) and dual femur neck regions (DF) b) BC by body weight, lean mass, fat mass using dual energy X-ray absorptiometry (DXA) at baseline, 6-months and 1-year in urban MSC women.nnnMETHODS AND STUDY DESIGNn76-primi-parous (28±3.2 yrs) randomly selected PP women (<7-days) were studied; 70 reassessed at 6- months and 42 1-yr PP. Data on anthropometry, BC, BMD at TB, APS and DF by DXA collected (baseline, 6- months, 1-yr PP).nnnRESULTSnWeight, waist and body mass index (BMI) decreased both at 6-month and 1-yr PP with respect to baseline (p<0.05). BC changes showed increase in android fat % at 1-yr by 10% over baseline (p<0.05). BMD with initial decline at 6-months (-2.8%, -2.3% and -2.3% respectively) recovered partially by 1-yr (+2.5% +1.2% and +4.8% respectively) at DF and TB with complete recovery at APS (p<0.05).nnnCONCLUSIONnThese urban relatively sedentary MSC women consumed fat rich food PP with higher android fat retention and partial recovery of BMD at DF and TB at 1-year. Modifications in activity and dietary nutrient intakes may be necessary to prevent cardiovascular and bone health related risks.

Randomized control trial assessing impact of increased sunlight exposure versus Vitamin D supplementation on lipid profile in Indian Vitamin D deficient men

Background: Despite abundance of sunshine in India, Vitamin D deficiency is common and therefore there is an increasing trend toward taking Vitamin D supplements either as prescription medicine or as a nutritional supplement. Studies have suggested that duration of sun exposure may influence serum lipid profile. Objectives: To study the effect of increased sunlight exposure versus Vitamin D supplementation on Vitamin D status and lipid profile in individuals with Vitamin D deficiency (25-hydroxyvitamin-D [25OHD] <50 nmol/L). Design: A prospective, randomized open-label trial was carried out in apparently healthy Indian men (40–60 years). Based on 25OHD concentrations, individuals were divided into control (>50 nmol/L, n = 50) and intervention (<50 nmol/L, n = 100) groups. Individuals from intervention group were randomly allocated to two groups; either “increased sunlight exposure group” (n = 50, received at least 20 min sunlight exposure to forearms and face between 11 a.m. and 3 p.m. over and above their current exposure) or “cholecalciferol supplement group” (n = 50, received oral cholecalciferol 1000 IU/day). Results: Significant increase in 25OHD concentrations was seen in both intervention groups (P < 0.01). Significant decrease in total cholesterol (TC), high-density-lipoprotein cholesterol (HDL-C), and low-density-lipoprotein cholesterol (LDL-C) was seen in individuals with increased sunlight exposure (P < 0.05). Cholecalciferol supplement group showed a significant increase in TC and HDL-C (P < 0.05) and insignificant increase in LDL-C. Conclusions: Increase in Vitamin D concentrations through sunlight exposure significantly reduced TC, LDL-C, and HDL-C concentrations, and cholecalciferol supplementation increased TC and HDL-C concentrations.

Relationship of insulin-like growth factor 1 and bone parameters in 7–15 years old apparently, healthy Indian children

Objective: Growth hormone through insulin-like growth factor 1 (IGF-1) plays an important role in both bone growth and mineralization. This cross-sectional study was carried out to evaluate the relationship between serum IGF-1 concentrations and dual energy X-ray (DXA) measured whole body less head bone area (BA), lean body mass (LBM), and bone mineral content (BMC). Methods: One hundred and nineteen children (boys = 70, age = 7.3–15.6 years) were studied for their anthropometric parameters by standard methods and bone and body composition by DXA. Their fasting serum IGF-1 concentrations were assessed by enzyme-linked immunosorbent assay and Z-scores were calculated using available reference data. Bone and body composition parameter Z-scores were calculated using ethnic reference data. Results: Mean age of the boys and girls was similar (11.5 ± 1.8 years). The mean serum IGF-1concentrations and IGF-1 Z-scores were similar (P > 0.1) between boys and girls and were of the order of (302.3 ± 140.0 and − 1.4 ± 1.1, respectively). The LBM for age and BA for age Z-score was greater in children with IGF-1 Z-score > median than children with IGF-1 Z-score < median. The mean BMC for age Z-scores were 0.4 ± 0.9 and − 0.2 ± 0.8 in children with above and below the median of IGF-1 Z-score (P > 0.1). Conclusion: Serum IGF-1 levels were more strongly associated with BA and LBM, suggesting that its effect on bone is greater with respect to periosteal bone acquisition and through its effect on muscle mass.

Bone mineral content in growth hormone deficient children treated with growth hormone after withdrawal of supplementation with calcium, vitamin D and zinc

Supplementation with calcium (ca), vitamin d (vit D), zinc has been shown to have a positive effect on bone mineral content (BMC) gain in growth hormone deficient (GHD) children on GH therapy[1]. It is unknown if this gain is sustained after supplement withdrawal. We aimed to investigate the influence of prior supplementation with ca, vitD and zinc on BMC accretion after supplement withdrawal. 31 prepubertal GHD children were randomly allocated to receive A) calcium (500mg/d), vitamin d (30,000 IU/3 months) and B) calcium (500mg/d), vitamin D (30,000 IU/3 months) & zinc (8 mg) for 1 year with GH. Ht measurement, bone mineralization by dual energy x-ray absorptiometry, tanner staging were performed at 4 timepoints, baseline, post 1 year of supplementation and 1 & 2 years after withdrawal of supplementation. Height for age z-scores (HAZ) were calculated from ethnic growth references. At baseline, children (18 boys, 9.6±2.8 years) from group A & B were similar in their HAZ (-4 ±1.5, -4 ±1.3) and BMC (370±215 g, 440±167g). 1 year post supplementation, 40% & 36% children and by the end of 2 year of supplementation withdrawal, 47% & 80% from group A & B respectively had entered puberty. Since Ht has strong correlation with BMC, % change in ht adjusted BMC was analyzed. The gain in BMC was greater (p < 0.05) in group B (51 %) children than in group A (49 %) children. However, after the withdrawal of the supplementation, the % gain in ht as well as ht adjusted BMC was similar in both groups. The % gain in ht adjusted BMC was lower (p <0.05) in the 1 year of supplement withdrawal (22 %). In 2 year, the ht adjusted BMC showed a significantly greater (53 %, p < 0.05) gain than the supplementation year and first year after supplementation withdrawal. Effect of short term supplementation with ca, vit D & zn in GH treated GHD children may not continue after the withdrawal of supplementation. However, the greater gain in the 2 year after supplementation withdrawal was possibly due to the effect of puberty.

Duration of casual sunlight exposure necessary for adequate Vitamin D status in Indian Men

Objectives: To investigate the duration of casual sunlight ultraviolet-B (UVB) exposure required to maintain optimal Vitamin D status (25-hydroxyvitamin-D [25(OH)D]) >50 nmol/L in urban Indian men, using polysulfone (PSU) dosimeters and a sunlight exposure questionnaire. Methods: In healthy men (aged 40–60 years) from Pune (18.52° N, 73.86° E), India, serum 25(OH)D was measured using enzyme-linked immunosorbent assay. Sunlight exposure was assessed using PSU dosimeter and by questionnaire. Results: Of 160 men (48.3 ± 5.6 years), 26.8% were deficient and 40.6% had insufficient Vitamin D concentrations. A hyperbolic function for the relationship between PSU measured sunlight exposure in standard erythema dose (SED) and serum 25(OH)D concentrations (r = 0.87, P < 0.01) revealed that daily exposure of 1 SED was sufficient to maintain serum 25(OH)D concentrations over 50 nmol/L. The curve plateaued around 5 SED (80 nmol/L) and extrapolation of the curve (>5 SED) did not increase 25(OH)D concentrations above 90 nmol/L. Receiver operating curve analysis confirmed that 1 SED-UV exposure was sufficient to maintain 25(OH)D concentrations over 50 nmol/L. Based on the questionnaire data, >1 h of midday casual sunlight exposure was required to maintain serum 25(OH)D concentrations above 50 nmol/L. Duration of sunlight exposure assessed by questionnaire and PSU dosimeter showed a significant correlation (r = 0.517, P < 0.01). Conclusion: In urban Indian men, >1 h of casual midday sunlight exposure daily was required to maintain serum 25(OH)D concentrations above 50 nmol/L, and >2 h of casual sunlight exposure was needed to maintain 25(OH)D concentrations above 75 nmol/L. Excess sunlight did not increase 25(OH)D linearly. The sunlight exposure questionnaire was validated for use in clinical studies and surveys.