Valores de referencia de la fuerza prensil en escolares colombianos. Estudio FUPRECOL

The primary aim of this study was to generate normative handgrip strength (HG) data for 10- to 17.9-year-olds. The secondary aim was to determine the relative proportion of Colombian children and adolescents that fall into established Health Benefit Zones (HBZ). This cross-sectional study is enrolling 7268 schoolchildren (boys n=3129 and girls n=4139, age 12.7 (2.4) years old. HG was measured using a hand dynamometer with an adjustable grip. Five HBZs (Needs Improvement, Fair, Good, Very Good, and Excellent) have been established that correspond to combined-HG. Centile smoothed curves, percentile and tables for the 3rd, 10th, 25th, 50th, 75th, 90th and 97th percentile were calculated using Cole’s LMS method. HG peaked in the sample at 22.2 (8.9) kg in boys and 18.5 (5.5) kg in girls. The increase in HG was greater for boys than for girls, but the peak HG was lower in girls than in boys. The HBZ data indicated that a higher overall percentage of boys than girls at each age group fell into the “Needs Improvement” zone, with differences particularly pronounced during adolescence. Our results provide, for the first time, sex- and age-specific HG reference standards for Colombian schoolchildren aged 9-17.9 years.

The effects of nutrition, puberty and dancing on bone density in adolescent ballet dancers.

Ballet dancers have on average a low bone mineral content (BMC), with elevated fracture-risk, low body mass index (BMI) for age (body mass index, kg/m2), low energy intake, and delayed puberty. This study aims at a better understanding of the interactions of these factors, especially with regard to nutrition. During a competition for pre-professional dancers we examined 127 female participants (60 Asians, 67 Caucasians). They averaged 16.7 years of age, started dancing at 5.8 years, and danced 22 hours/week. Assessments were made for BMI, BMC (DXA), and bone mineral apparent density (BMAD) at the lumbar spine and femoral neck, pubertal stage (Tanner score), and nutritional status (EAT-40 questionnaire and a qualitative three-day dietary record). BMI for age was found to be normal in only 42.5% of the dancers, while 15.7% had a more or less severe degree of thinness (12.6% Grade2 and 3.1% Grade 3 thinness). Menarche was late (13.9 years, range 11 to 16.8 years). Food intake, evaluated by number of consumed food portions, was below the recommendations for a normally active population in all food groups except animal proteins, where the intake was more than twice the recommended amount. In this population, with low BMI and intense exercise, BMC was low and associated with nutritional factors; dairy products had a positive and non-dairy proteins a negative influence. A positive correlation between BMAD and years since menarche confirmed the importance of exposure to estrogens and the negative impact of delayed puberty. Because of this and the probable negative influence of a high intake of non-dairy proteins, such as meat, fish, and eggs, and the positive association with a high dairy intake, ballet schools should promote balanced diets and normal weight and should recognize and help dancers avoid eating disorders and delayed puberty caused by extensive dancing and inadequate nutrition.

The association between coronary artery calcification progression and loss of bone density in non-dialyzed CKD patients

Background: Coronary artery calcification (CAC) and low bone density are coexisting deleterious conditions commonly shared by chronic kidney disease (CKD) patients. In the present study, we aimed to investigate whether the progression of CAC was associated with overtime reduction in bone density in non-dialyzed CKD patients. Methods: This is a prospective study of 24 months including 72 non-dialyzed CKD patients Stages 2 - 4 (age 57.6 +/- 10.3 years, 62% male, 22% diabetics). CAC and vertebral bone density (VBD) were measured by computed tomography. Results: At baseline, 46% of the patients had CAC (calcified group) and calcification was not identified in 54% of the patients (non-calcified group). The calcified group was older, predominantly male, and had lower VBD in comparison to non-calcified group. CAC progression was observed only in the calcified group (91% of the patients increased calcium score). The multiple regression analysis revealed loss of VBD as the independent determinant of CAC progression in these patients. Conclusion: CAC progression was associated with loss of VBD in non-dialyzed CKD patients.

Non-invasive quantitative estimation of bone density in rats throughout the life cycle and in arthritic osteopenia: preliminary results

A longitudinal bone survey was conducted in 86 female Wistar rats in order to assess mineral density kinetics from young age (5 weeks: 115 g) till late adulthood (64 weeks: 586 g). In vivo quantitative radiographic scanning was performed on the caudal vertebrae, taking trabecular mass as the parameter. Measurements were expressed as Relative Optical Density (ROD) units by means of a high resolution densitometric device. Results showed a progressive increase in mineral density throughout the life cycle, with a tendency to level in the higher weight range, indicating that progressive mineral aposition occurs in rats in dependency of age. This phenomenon, however, should be always considered within the context of continuous skeletal growth and related changes typical of this species. Twelve different animals were also examined following induction of articular inflammation with Freund's adjuvant in six of them. Bone survey conducted 12 to 18 days after inoculation revealed a significant (P less than 0.01) reduction in trabecular bone mass of scanned vertebrae in comparison with the weight-matched untreated controls. It is concluded that the in vivo quantitative assessment of bone density illustrated in this report represents a sensitive and useful tool for the long-term survey of naturally occurring or experimentally induced bone changes. Scanning of the same part of the skeleton can be repeated, thereby avoiding sacrifice of the animal and time-consuming preparation of post-mortem material.

Osteocyte lacunar density and area in newly formed bone of the augmented sinus

OBJECTIVES Osteocytes, the most common cells of the bone, are buried in lacunae. Density and area of the osteocyte lacunae change with increasing maturation of the newly formed bone. Evaluation of osteocyte lacunae can therefore provide insights into the process of graft consolidation. MATERIALS AND METHODS Here, we determined the osteocyte lacunar density (number of osteocyte lacunae per bone area; N.Ot/BAr) and the osteocyte lacunar area in μm(2) (Lac.Ar) in histological specimens 6 and 12 weeks after the sinuses of 10 minipigs were augmented with Bio-Oss(®) , a deproteinized bovine bone mineral, and Ostim(®) , an aqueous paste of synthetic nanoparticular hydroxyapatite. The region of interest was defined by the following criteria: (i) >1 mm from the host bone, (ii) >0.5 mm from the sinus mucosa, (iii) minimum area of 0.2 mm(2) , and (iv) bone tissue spanning at least two bone substitute particles. RESULTS The overall osteocyte lacunar density was significantly higher in the Bio-Oss(®) group than in the Ostim(®) group and decreased during the observation period at a similar range in both groups. The osteocyte lacunar area was smaller in the Bio-Oss(®) group than the Ostim(®) group but there was no significant change within the groups over time. CONCLUSIONS These results suggest that bone substitutes affect the osteocyte lacunar density and the osteocyte lacunar area in the newly formed bone within the augmented sinus in this particular model situation. These measures can provide insights into the maturation of newly formed bone in the augmented sinus.

Double disruption of alpha(2A)- and alpha(2C)-adrenoceptors results in sympathetic hyperactivity and high-bone-mass phenotype

Evidence demonstrates that sympathetic nervous system (SNS) activation causes osteopenia via beta(2)-adrenoceptor (beta(2)-AR) signaling. Here we show that female mice with chronic sympathetic hyperactivity owing to double knockout of adrenoceptors that negatively regulate norepinephrine release, alpha(2A)-AR and alpha(2C)-AR(alpha(2A)/alpha(2C)-ARKO), present an unexpected and generalized phenotype of high bone mass with decreased bone resorption and increased formation. In alpha(2A)/alpha(2C)-ARKO versus wild-type (WT) mice, micro-computed tomographic (mu CT) analysis showed increased, better connected, and more plate-shaped trabeculae in the femur and vertebra and increased cortical thickness in the vertebra, whereas biomechanical analysis showed increased tibial and femoral strength. Tibial mRNA expression of tartrate-resistant acid phosphatase (TRACP) and receptor activator of NF-kappa B (RANK), which are osteoclast-related factors, was lower in knockout (KO) mice. Plasma leptin and brain mRNA levels of cocaine amphetamine-regulated transcript (CART), which are factors that centrally affect bone turnover, and serum levels of estradiol were similar between mice strains. Tibial beta(2)-AR mRNA expression also was similar in KO and WT littermates, whereas alpha(2A)-, alpha(2B)- and alpha(2C)-AR mRNAs were detected in the tibia of WT mice and in osteoblast-like MC3T3-E1 cells. By immunohistochemistry, we detected alpha(2A)-, alpha(2B)-, alpha(2C)- and beta(2)-ARs in osteoblasts, osteoclasts, and chondrocytes of 18.5-day-old mouse fetuses and 35-day-old mice. Finally, we showed that isolated osteoclasts in culture are responsive to the selective alpha(2)-AR agonist clonidine and to the nonspecific alpha-AR antagonist phentolamine. These findings suggest that beta(2)-AR is not the single adrenoceptor involved in bone turnover regulation and show that alpha(2)-AR signaling also may mediate the SNS actions in the skeleton. (c) 2011 American Society for Bone and Mineral Research.

Is Nitric Oxide a Mediator of the Effects of Low-Intensity Electrical Stimulation on Bone in Ovariectomized Rats?

Low-intensity electrical stimulation (LIES) may counteract the effects of ovariectomy (OVX) on nitric oxide synthase (NOS) expression, osteocyte viability, bone structure, and microarchitecture in rats (Lirani-Galvo et al., Calcif Tissue Int 84:502-509, 2009). The aim of the present study was to investigate if these effects of LIES could be mediated by NO. We analyzed the effects of NO blockage (by l-NAME) in the response to LIES on osteocyte viability, bone structure, and microarchitecture in OVX rats. Sixty rats (200-220 g) were divided into six groups: sham, sham-l-NAME (6 mg/kg/day), OVX, OVX-l-NAME, OVX-LIES, and OVX-LIES-l-NAME. After 12 weeks, rats were killed and tibiae collected for histomorphometric analysis and immunohistochemical detection of endothelial NOS (eNOS), inducible NOS (iNOS), and osteocyte apoptosis (caspase-3 and TUNEL). In the presence of l-NAME, LIES did not counteract the OVX-induced effects on bone volume and trabecular number (as on OVX-LIES). l-NAME blocked the stimulatory effects of LIES on iNOS and eNOS expression of OVX rats. Both l-NAME and LIES decreased osteocyte apoptosis. Our results showed that in OVX rats l-NAME partially blocks the effects of LIES on bone structure, turnover, and expression of iNOS and eNOS, suggesting that NO may be a mediator of some positive effects of LIES on bone.

Low-Intensity Electrical Stimulation Counteracts the Effects of Ovariectomy on Bone Tissue of Rats: Effects on Bone Microarchitecture, Viability of Osteocytes, and Nitric Oxide Expression

Low Intensity Electrical Stimulation (LIES) has been used for bone repair, but little is known about its effects on bone after menopause. Osteocytes probably play a role in mediating this physical stimulus and they could act as transducers through the release of biochemical signals, such as nitric oxide (NO). The aim of the present study was to investigate the effects of LIES on bone structure and remodeling, NOS expression and osteocyte viability in ovariectomized (OVX) rats. Thirty rats (200-220 g) were divided into 3 groups: SHAM, OVX, and OVX subjected to LIES (OVX + LIES) for 12 weeks. Following the protocol, rats were sacrificed and tibias were collected for histomorphometric analysis and immunohistochemical detection of endothelial NO synthase (eNOS), inducible NOS (iNOS), and osteocyte apoptosis (caspase-3 and TUNEL). OVX rats showed significant (p < 0.05 vs. SHAM) decreased bone volume (10% vs. 25%) and trabecular number (1.7 vs. 3.9), and increased eroded surfaces (4.7% vs. 3.2%) and mineralization surfaces (15.9% vs. 7.7%). In contrast, after LIES, all these parameters were significantly different from OVX but not different from SHAM. eNOS and iNOS were similarly expressed in subperiosteal regions of tibiae cortices of SHAM, not expressed in OVX, and similarly expressed in OVX + LIES when compared to SHAM. In OVX, the percentage of apoptotic osteocytes (24%) was significantly increased when compared to SHAM (11%) and OVX + LIES (8%). Our results suggest that LIES counteracts some effects of OVX on bone tissue preserving bone structure and microarchitecture, iNOS and eNOS expression, and osteocyte viability.

Changes in bone mass, biomechanical properties, and microarchitecture of calcium- and iron-deficient rats fed diets supplemented with inulin-type fructans

Feeding mineral-deficient diets enhances absorptive efficiency as an attempt of the body to compensate for the lack of an essential nutrient. Under certain circumstances, it does not succeed, and nutritional deficiency is produced Our hypothesis was that mulin-type fructans (ITF), which arc known to affect mineral absorption, could increase Ca and Fe bioavailability in Ca- and Fe-deficient rats. Male Wistar rats (n = 48, 4 weeks old) were assigned to I of 8 groups derived from 2 x 2 x 2 factorial design with 2 levels of added Fe (0 and 35 mg/kg), Ca (0 and 5 g/kg), and ITF (0 and 100 g/kg) for 33 days. The Fe status (hemoglobin, serum Fe, total Fe-binding capacity, transferrin saturation, liver minerals) was evaluated. Tibia minerals (Ca, Mg, and Zn), bone strength, and histomorphometry were determined In nondeficient rats, ITF supplementation did not affect Fe status or organ minerals, with the exception of tibia Mg Moreover, ITF improved bone resilience and led to a reduction in eroded surface per body surface and number of osteoclasts per area In Ca-deficient rats, ITF increased liver (Fe and Zn) and tibia (Zn) mineral levels but impaired tibia Mg, yield load, and resilience. In conclusion, ITF worsened the tibia Mg levels and elastic properties when supplemented in Ca-deficient diets In contrast, although bone Ca was not affected in nondeficient rats under the present experimental conditions, bone quality improved, as demonstrated by a moderate reduction in femur osteoclast resorption and significant increases in tibia Mg content and elasticity. (C) 2009 Elsevier Inc. All rights reserved.

RANKL is a mediator of bone resorption in idiopathic hypercalciuria

Background and objectives: This study aimed to determine the expression of osteoprotegerin, receptor activator of nuclear factor kappa B ligand, interleukin-la, transforming growth factor-beta, and basic fibroblast growth factor in stone-forming patients with idiopathic hypercalciuria. Design, setting, participants, & measurements: Immunohistochemical analysis was performed in undecalcified bone samples previously obtained from 36 transiliac bone biopsies of patients who had idiopathic hypercalciuria and whose histomorphometry had shown lower bone volume, increased bone resorption, and prolonged mineralization lag time. Results: Bone expression of receptor activator of nuclear factor kappa B ligand and osteoprotegerin was significantly higher in patients with idiopathic hypercalciuria versus control subjects. Transforming growth factor-beta immunostaining was lower in patients with idiopathic hypercalciuria than in control subjects and correlated directly with mineralization surface. Interleukin-la and basic fibroblast growth factor staining did not differ between groups. Receptor activator of nuclear factor kappa B ligand bone expression was significantly higher in patients who had idiopathic hypercalciuria and exhibited higher versus normal bone resorption. Conclusion: A higher expression of receptor activator of nuclear factor kappa B ligand in bone tissue suggests that increased bone resorption in patients with idiopathic hypercalciuria is mediated by receptor activator of nuclear factor kappa B ligand. Osteoprotegerin bone expression might have been secondarily increased in an attempt to counteract the actions of receptor activator of nuclear factor kappa B ligand. The low bone expression of transforming growth factor-beta could contribute to the delayed mineralization found in such patients.

Influence of Estrogen Deficiency on Bone Around Osseointegrated Dental Implants: An Experimental Study in the Rat Jaw Model

Purpose: The aim of this study was to evaluate the influence of estrogen deficiency on bone around osseointegrated dental implants in a rat jaw model. Materials and Methods: This study used 16 female rats that had the first molars bilaterally extracted and were allowed to heal for 30 days before implant placement. Sixty days after implant placement, the animals were randomly subjected to sham surgery or ovariectomy (OVX). The animals were euthanized 90 days after OVX. Bone-to-implant contact, bone area fraction occupancy between implant threads, mineral density, turnover markers, and cells positive for tartrate-resistant acid phosphatase were assessed for the 2 groups. Results: The results showed that OVX group presented a decrease of systemic bone density, alterations in bone turnover markers, and an increase of cells positive for tartrate-resistant acid phosphatase compared with the sham-surgery group. However, no difference relative to bone-to-implant contact and bone area fraction occupancy was observed between groups. Conclusions: The findings of this study demonstrate that estrogen deficiency may not be considered a risk factor for osseointegrated implant failure in jaw bone. (C) 2011 American Association of Oral and Maxillofacial Surgeons J Oral Maxillofac Surg 69:1911-1918, 2011

Effects of magnesium intake deficiency on bone metabolism and bone tissue around osseointegrated implants

Objectives: This study evaluated the effect of magnesium dietary deficiency on bone metabolism and bone tissue around implants with established osseointegration. Materials and methods: For this, 30 rats received an implant in the right tibial metaphysis. After 60 days for healing of the implants, the animals were divided into groups according to the diet received Control group (CTL) received a standard diet with adequate magnesium content, while test group (Mg) received the same diet except for a 90% reduction of magnesium. The animals were sacrificed after 90 days for evaluation of calcium, magnesium, osteocalcin and parathyroid hormone (PTH) serum levels and the deoxypyridinoline (DPD) level in the urine. The effect of magnesium deficiency on skeletal bone tissue was evaluated by densitometry of the lumbar vertebrae, while the effect of bone tissue around titanium implants was evaluated by radiographic measurement of cortical bone thickness and bone density. The effect on biomechanical characteristics was verified by implant removal torque testing. Results: Magnesium dietary deficiency resulted in a decrease of the magnesium serum level and an increase of PTH and DPD levels (P <= 0.05). The Mg group also presented a loss of systemic bone mass decreased cortical bone thickness and lower values of removal torque of the implants (P <= 0.01). Conclusions: The present study concluded that magnesium-deficient diet had a negative influence on bone metabolism as well as on the bone tissue around the implants.

Osteoprotegerin/RANKL system imbalance in active polyarticularonset juvenile idiopathic arthritis: a bone damage biomarker?

Objective: To evaluate the importance of receptor activator of nuclear factor kappa B (RANK)/receptor activator of nuclear factor kappa B ligand (RANKL)/osteoprotegerin (OPG) modulation in active polyarticular juvenile idiopathic arthritis (pJIA) patients with and without bone erosions. Methods: Thirty female patients (mean age 11.07 +/- 3.77 years, range 4-17 years) with active pJIA and 30 healthy gender-and age-matched controls were consecutively selected for this study. All involved articulations were assessed by X-ray and examined for the presence of bone erosions. The serum levels of RANKL and OPG were measured using an enzyme-linked immunosorbent assay (ELISA). Results: Patients with active pJIA had higher levels of serum RANKL than controls [2.90 (0.1-37.4) vs. 0.25 (0.1-5.7) pg/mL, p=0.007] and a lower OPG/RANKL ratio [21.25 (1.8-897.6) vs. 347.5 (9-947.8), p=0.005]. However, levels of OPG were comparable in both groups [55.24 (28.34-89.76) vs. 64.42 (30.68-111.28) pg/mL, p=0.255]. Higher levels of serum RANKL and a lower OPG/RANKL ratio were also observed in active pJIA patients with bone erosions compared to controls [3.49 (0.1-37.4) vs. 0.25 (0.1-5.7) pg/mL, p=0.0115 and 14.3 (1.8-897.6) vs. 347.5 (9-947.8), p=0.016]. However, RANKL levels and OPG/RANKL ratio were similar in pJIA patients without bone erosion and controls [1.75 (0.1-10.9) vs. 0.25 (0.1-5.7) pg/mL, p=0.055 and 29.2 (3.3-756.8) vs. 347.5 (9-947.8), p=0.281]. Conclusion: These data suggest that active pJIA with bone erosions is associated with high serum levels of RANKL and a low OPG/RANKL ratio, indicating that these alterations may reflect bone damage in this disease.

The Bone Histology Spectrum in Experimental Renal Failure: Adverse Effects of Phosphate and Parathyroid Hormone Disturbances

Bone disease is a common disorder of bone remodeling and mineral metabolism, which affects patients with chronic kidney disease. Minor changes in the serum level of a given mineral can trigger compensatory mechanisms, making it difficult to evaluate the role of mineral disturbances in isolation. The objective of this study was to determine the isolated effects that phosphate and parathyroid hormone (PTH) have on bone tissue in rats. Male Wistar rats were subjected to parathyroidectomy and 5/6 nephrectomy or were sham-operated. Rats were fed diets in which the phosphate content was low, normal, or high. Some rats received infusion of PTH at a physiological rate, some received infusion of PTH at a supraphysiological rate, and some received infusion of vehicle only. All nephrectomized rats developed moderate renal failure. High phosphate intake decreased bone volume, and this effect was more pronounced in animals with dietary phosphate overload that received PTH infusion at a physiological rate. Phosphate overload induced hyperphosphatemia, hypocalcemia, and changes in bone microarchitecture. PTH at a supraphysiological rate minimized the phosphate-induced osteopenia. These data indicate that the management of uremia requires proper control of dietary phosphate, together with PTH adjustment, in order to ensure adequate bone remodeling.

Newly Formed Bone in Mandible Decortication Experimental Model Using rhBMP-2 Evaluated by Densitometric Study

The purpose of this study was to evaluate the newly formed bone, comparing two different carriers for rhBMP-2, using the decortication and nondecorticatication surgical technique in Wistar rat mandibles, evaluated by radiographic densitometry method. It was used fifty six animals according to specific treatment, which were sacrificed after 3 and 6 weeks after this. It was concluded that the decortication surgical technique was able to optimize the osteoinduction properties of the rhBMP-2, independently of the material carrier used and the period of time, according to radiographic densitometry technique.