Interrelationships between densitometric, geometric, and mechanical properties of rat femora: inferences concerning mechanical regulation of bone modeling

The Influence of Cement Thickness within the Cap on Stress Distribution for Dental Implants

The purpose of this finite element analysis (FEA) was to evaluate the stress distribution within the prosthetic components and bone in relation to varying cement thicknesses (from 20 to 60 μm) utilized to attach a zirconia crown on a conometric cap. The study focused on two types of implants (Cyroth and TAC, AoN Implants, Grisignano di Zocco, Italy) featuring a Morse cone connection. Detailed three-dimensional (3D) models were developed to represent the bone structure (cortical and trabecular) and the prosthetic components, including the crown, cement, cap, abutment, and the implant. Both implants were placed 1.5 mm subcrestally and subjected to a 200 N load at a 45° inclination on the crown. The results indicated that an increase in cement thickness led to a reduction in von Mises stress on the cortical bone for both Cyroth and TAC implants, while the decrease in stress on the trabecular bone (apical zone) was relatively less pronounced. However, the TAC implant exhibited a higher stress field in the apical area compared to the Cyroth implant. In summary, this study investigated the influence of cement thickness on stress transmission across prosthetic components and peri-implant tissues through FEA analysis, emphasizing that the 60 μm cement layer demonstrated higher stress values approaching the material strength limit.

Effects of enzyme supplementation on growth performance, digestibility of phosphorus, femur parameters and fecal microbiota in growing pigs fed different types of diets

A 42-days study was conducted to evaluate the effects of different dietary types (corn-or wheat-soybean meal-based diet) and phytase (Phy) or a multi-carbohydrase and phytase complex (MCPC) supplementation on growth performance, digestibility of phosphorus (P), intestinal transporter gene expression, plasma indexes, bone parameters, and fecal microbiota in growing pigs. Seventy-two barrows (average initial body weight of 24.70 ± 0.09 kg) with a 2 × 3 factorial arrangement of treatments and main effects of diet type (corn-or wheat-soybean meal-based-diets) and enzyme supplementation (without, with Phy or with MCPC). Each group was designed with 6 replicate pens. The MCPC increased (p < 0.05) average daily gain (ADG) and final body weight (BW). A significant interaction (p = 0.01) was observed between diet type and enzyme supplementation on apparent total tract digestibility (ATTD) of P. The ATTD of P was higher (p < 0.05) in wheat soybean meal-based diets compared to corn-soybean meal-based diets. Compared with the corn-soybean meal-based diet, the relative expression of SLC34A2 and VDR genes in the ileum and SLC34A3 in jejunum of growing pigs fed the wheat-soybean meal based diet was lower (p < 0.05). The MCPC significantly reduced (p < 0.05) the relative expression of TRPV5 and CALB1 genes in the ileum and increased the expression of CALB1 in the duodenum compared to control diet. The phytase increased (p < 0.05) the relative expression of SLC34A1 gene in the duodenum in comparison to control diet and MCPC-supplemented diet. The Ca and P contents in plasma from pigs fed corn-soybean meal-based diet were higher (p < 0.05) than those from pigs fed wheat-soybean meal-based diet, and the parathyroid hormone (PTH) and calcitonin (CT) concentrations were lower (p < 0.05) than those fed wheat-soybean meal-based diet. The content of Ca and P in the femur and the bone strength of pigs in the corn-soybean meal group were significantly higher (p < 0.05) than those in the wheat-soybean meal groups. The phytase increased (p < 0.05) the Ca and P content and bone strength of the femur. Additionally, diet type and both enzymes significantly improved fecal microbial diversity and composition. Taken together, diet type and exogenous enzymes supplementation could differently influence the growth performance, utilization of phosphorus, intestinal transporter gene expression, bone mineralization and microbial diversity and composition in growing pigs.

The Use of Splinted Versus Nonsplinted Prosthetic Design in Dental Implants: A Literature Review

The choice of a splinted or nonsplinted implant-supported prosthesis should be based on solid scientific evidence that considers the conditions and needs of each patient. This review elaborates on the factors that directly influence clinical decisions between splinted or nonsplinted dental implants. Digital and manual searches of the published literature were conducted to identify studies that examined splinted prostheses (SPs) and nonsplinted prostheses (NSPs). The search terms used, alone or in combination, were "splinting prosthesis," "nonsplinting prosthesis," "prosthetic design," "stress distribution in dental implant," "implant loading," "implant occlusion," and "crestal bone resorption." Ninety-four studies were selected to compare and address the details emphasized in this study. Thirty-four reported articles were not directly related to restoration design but were reviewed to better understand the influence of mechanical risk factors, finite element analysis limits, and criteria for implant survival and treatment success. There are advantages and disadvantages of splinting implants together. NSPs are the ideal choice because they resemble natural teeth. Splinting a restored implant will cause the implant to appear as part of one unit and is indicated in more compromised situations, unfavorable conditions, or when pontic spaces and cantilevers are needed in implant prostheses.

Strontium Ranelate and Strontium Chloride Supplementation Influence on Bone Microarchitecture and Bone Turnover Markers-A Preliminary Study

Despite strontium ranelate use in osteoporosis management being one of the promising concepts in disease treatment, there is no clear evidence that strontium organic compounds are more effective than inorganic ones. The aim of this study was to compare strontium chlorate and strontium ranelate influence on the mice bone microarchitecture. We investigated whether strontium chlorate (7.532 mmol/L) and strontium ranelate (7.78 mmol/L) solutions fed to healthy SWISS growing mice (n = 42) had an influence on the percent of bone volume (BV/TV), trabecular thickness (Tb.Th), number of trabeculae (Tb.N), and separation between each trabecula (Tb.Sp) in the chosen ROI (region of interest) in the distal metaphysis of the left femurs. The cortical bone surface was examined close to the ROI proximal scan. There was an increase in each examined parameter compared with the control group. There were no statistical differences between strontium ranelate and strontium chlorate parameters. Our study indicates that organic and inorganic strontium compounds similarly affect the bone microarchitecture and strength.

The effect of caponization on bone homeostasis of crossbred roosters. I. Analysis of tibia bone mineralization, densitometric, osteometric, geometric and biomechanical properties

The presented study focuses on assessing the effect of caponization on the densitometric, osteometric, geometric and biomechanical parameters of tibial bones in crossbred chickens. The study was carried out on 96 hybrids between Yellowleg Partridge hens (Ż-33) and Rhode Island Red cockerels (R-11) aged 16 weeks, 20 weeks and 24 weeks. Birds were randomly assigned to 2 groups-the control group (n = 48; which consisted of intact roosters) and the experimental group (n = 48, which consisted of individuals subjected to caponization at the age of 8 weeks). The caponization had no effect on the densitometric, osteometric and geometric parameters (except the horizontal internal diameter of 16-week-old individuals) of tibia bone, as well as the content of calcium (Ca), phosphorus (P) and the Ca/P ratio in the bone mineral fraction in all analyzed age groups of animals. However, it contributes to a lower percentage of ash in the bones of capons at 20 and 24 weeks of age compared to cockerels. On the contrary, some mechanical and material parameters show the negative effect of caponization. Ultimate load and bending moment decreased in capons in all of the analyzed age groups of animals and yield load, stiffness and ultimate stress also decreased but only in the group of 20-week-old and 24-week-old individuals. This can contribute to the weakening of the capon bones, and in the perspective of prolonged maintenance to their deformation and even fracture.

Effect of Fermented Rapeseed Meal in Feeds for Growing Piglets on Bone Morphological Traits, Mechanical Properties, and Bone Metabolism

Quality feed is essential for correct bone development and proper functioning of animals. Post-weaned piglets experience a radical change in eating behaviour that can influence their feed intake. For this reason, functional feed additives and ingredients that can be used in post-weaning feeds are needed. The objective of this study was to evaluate the effects of partially replacing wheat with rapeseed meal fermented using Bacillus subtilis strain 87Y on overall bone quality and bone metabolism in weaner piglets. From the 28th day of life, barrows were fed either a standard wheat-based diet or a diet containing 8% fermented rapeseed meal (FRSM) with or without a feed additive containing enzymes, antioxidants, probiotics, and prebiotics. The experimental period lasted 60 days, after which femur quality indices were assessed. Differences in bone length and weight were observed, but there were no changes in bone mineralization or bone mid-diaphysis morphometrical traits between treatments. FRSM inclusion reduced bone mid-diaphysis biomechanical properties, but these changes were dependent on feed-additive supplementation. Analysis of the levels of serum bone turnover markers suggests the intensification of bone resorption in FRSM-fed groups as deoxypyridinoline levels increase. The results obtained warrant further research on what the disturbances in bone mechanical properties and metabolism observed in FRSM-fed weaners means for the subsequent fattening period.

Model-Based Optimization of Laser Excitation and Detection Improves Spectral Contrast in Noninvasive Diffuse Raman Spectroscopy

Spatially offset Raman spectroscopy (SORS) is a powerful technique for subsurface molecular analysis of optically turbid samples. Numerical modeling of light propagation has been used to investigate opportunities for improving spectral contrast and signal to noise ratio when imaging regions of interest located 0-4.5 mm below the surface in polymer bulk material. Two- and three-dimensional modeling results demonstrate that when analyzing a certain region of interest (ROI) of finite lateral dimensions below the sample surface, offsetting both the laser source and detector in opposite directions from the central point of the ROI can increase the spectral contrast as compared to conventional SORS approach where the detector or the laser source is maintained at the central point (centered SORS). The outlined modeling results have been validated experimentally using a bulk polymer sample with a trans-stilbene ROI (cylinder) below the sample surface. The results show that modeling of the spatial configurations of laser excitation and detection points can be used to optimize the instrument configuration to achieve significant improvements (up to 2.25-fold) in performance over the conventional centered SORS. Such optimal solutions can then be implemented, for example, using robust fiber optic probes, moveable optics, or flexible spatial light modulator instruments for specific applications.

The Influence of Nesfatin-1 on Bone Metabolism Markers Concentration, Densitometric, Tomographic and Mechanical Parameters of Skeletal System of Rats in the Conditions of Established Osteopenia

Simple Summary

Nesfatin-1 is an adipokine with little known effect on the skeletal system. In this study, we examined the effect of 8-wk administration of nesfatin-1 on densitometric, tomographic, and mechanical parameters of bones, as well as the concentration of bone metabolism markers in rats with experimentally induced established osteopenia.

Abstract

Our study aimed to evaluate the impact of nesfatin-1 administration on bone metabolism and properties in established osteopenia in ovariectomized female rats. In total, 21 female Wistar rats were assigned to two groups: sham-operated (SHAM, n = 7) and ovariectomized (OVA, n = 14). After 12 weeks of osteopenia induction in the OVA females, the animals were given i.p. physiological saline (OVA, n = 7) or 2 µg/kg body weight of nesfatin-1(NES, n = 7) for the next 8 weeks. The SHAM animals received physiological saline at the same time. Final body weight, total bone mineral density and content of the skeleton were estimated. Then, isolated femora and tibias were subjected to densitometric, tomographic, and mechanical tests. Bone metabolism markers, i.e., osteocalcin, bone specific alkaline phosphatase (bALP), and crosslinked N-terminal telopeptide of type I collagen (NTx) were determined in serum using an ELISA kit. Ovariectomy led to negative changes in bone metabolism associated with increased resorption, thus diminishing the densitometric, tomographic, and mechanical parameters. In turn, the administration of nesfatin-1 led to an increase in the value of the majority of the tested parameters of bones. The lowest bALP concentration and the highest NTx concentration were found in the OVA females. The bALP concentration was significantly higher after nesfatin-1 administration in comparison to the OVA rats. In conclusion, the results indicate that nesfatin-1 treatment limits bone loss, preserves bone architecture, and increases bone strength in condition of established osteopenia.

Effect of Nesfatin-1 on Rat Humerus Mechanical Properties under Quasi-Static and Impact Loading Conditions

The investigations on the response of bone tissue under different loading conditions are important from clinical and engineering points of view. In this paper, the influence of nesfatin-1 administration on rat humerus mechanical properties was analyzed. The classical three-point bending and impact tests were carried out for three rat bone groups: control (SHO), the humerus of animals under the conditions of established osteopenia (OVX), and bones of rats receiving nesfatin-1 after ovariectomy (NES). The experiments proved that the bone strength parameters measured under various mechanical loading conditions increased after the nesfatin-1 administration. The OVX bones were most susceptible to deformation and had the smallest fracture toughness. The SEM images of humerus fracture surface in this group showed that ovariectomized rats had a much looser bone structure compared to the SHO and NES females. Loosening of the bone structure was also confirmed by the densitometric and qualitative EDS analysis, showing a decrease in the OVX bones’ mineral content. The samples of the NES group were characterized by the largest values of maximum force obtained under both quasi-static and impact conditions. The energies absorbed during the impact and the critical energy for fracture (from the three-point bending test) were similar for the SHO and NES groups. Statistically significant differences were observed between the mean F_{i max} values of all analyzed sample groups. The obtained results suggest that the impact test was more sensitive than the classical quasi-static three-point bending one. Hence, F_{i max} could be used as a parameter to predict bone fracture toughness.

The Influence of Prenatal Fumonisin Exposure on Bone Properties, as well as OPG and RANKL Expression and Immunolocalization, in Newborn Offspring Is Sex and Dose Dependent

The current study examined the effects of exposure of pregnant dams to fumonisins (FBs; FB1 and FB2), from the seventh day of pregnancy to parturition, on offspring bone metabolism and properties. The rats were randomly divided into three groups intoxicated with FBs at either 0, 60, or 90 mg/kg b.w. Body weight and bone length were affected by fumonisin exposure, irrespective of sex or dose, while the negative and harmful effects of maternal FBs’ exposure on bone mechanical resistance were sex and dose dependent. The immunolocalization of osteoprotegerin (OPG) and receptor activator of nuclear factor kappa-Β ligand (RANKL), in bone and articular cartilage, indicated that the observed bone effects resulted from the FB-induced alterations in bone metabolism, which were confirmed by the changes observed in the Western blot expression of OPG and RANKL. It was concluded that the negative effects of prenatal FB exposure on the general growth and morphometry of the offspring bones, as a result of the altered expression of proteins responsible for bone metabolism, were dose and sex dependent.

Serum PTH, PTH1R/ATF4 pathway, and the sRANKL/OPG system in bone as a new link between bone growth, cross-sectional geometry, and strength in young rats with experimental chronic kidney disease

The progression of chronic kidney disease (CKD) in children is associated with deregulated parathyroid hormone (PTH), growth retardation, and low bone accrual. PTH can cause both catabolic and anabolic impact on bone, and the activating transcription factor 4 (ATF4), a downstream target gene of PTH, is related to its anabolic effect. Osteoprotegerin (OPG) and receptor activator of NF-κB ligand (RANKL) are PTH-dependent cytokines, which may play an important role in the regulation of bone remodeling. This study aimed to evaluate the impact of endogenous PTH and the bone RANKL/OPG system on bone growth, cross-sectional geometry and strength utilizing young, nephrectomized rats. The parameters of cross-sectional geometry were significantly elevated in rats with CKD during the three-month experimental period compared with the controls, and they were strongly associated with serum PTH levels and the expression of parathyroid hormone 1 receptor (PTH1R)/ATF4 genes in bone. Low bone soluble RANKL (sRANKL) levels and sRANKL/OPG ratios were also positively correlated with cross-sectional bone geometry and femoral length. Moreover, the analyzed geometric parameters were strongly related to the biomechanical properties of femoral diaphysis. In summary, the mild increase in endogenous PTH, its anabolic PTH1R/ATF4 axis and PTH-dependent alterations in the bone RANKL/OPG system may be one of the possible mechanisms responsible for the favorable impact on bone growth, cross-sectional geometry and strength in young rats with experimental CKD.

Impaired bone microarchitecture and strength in patients with tumor-induced osteomalacia

Some studies based on bone biopsy have demonstrated that in patients with tumor-induced osteomalacia (TIO) the mineralization process of the bone matrix is profoundly disturbed. However, the interrelationship between clinical and biochemical features and bone microarchitecture in this disease needs further analysis. With this purpose in mind, we set out three objectives: (i) to determine bone microarchitecture and estimated bone strength in a group of patients with tumor-induced osteomalacia using high-resolution peripheral quantitative computed tomography (HR-pQCT) and finite element analysis (FEA), (ii) to investigate correlations between duration of disease, biochemical features, bone density, HR-pQCT and FEA parameters, and (iii) to compare HR-pQCT and FEA parameters with a healthy control group. Ten patients with TIO were included. All patients had non-resolved disease. At the distal radius, all bone microarchitecture parameters were significantly affected in patients with TIO in comparison with healthy controls. At the distal tibia, all parameters were significantly impaired, except for trabecular thickness. All the parameters were more affected in the distal tibia than in the distal radius. Women with TIO (n = 7) had significantly lower bone strength parameters than healthy controls. In men (n = 3), bone strength parameters were significantly lower than in the control group at the distal tibia. Alkaline phosphatase levels exhibited a negative correlation with microarchitecture parameters, failure load, and stiffness. Higher levels of parathyroid hormone correlated with poorer microarchitecture parameters. We believe that in TIO, hormonal disturbances and the lack of mechanical stimulus specially converge to generate an extremely harmful combination for bone health. © 2021 American Society for Bone and Mineral Research (ASBMR).

Severe Bone Microarchitecture Impairment in Women With Pregnancy and Lactation-Associated Osteoporosis

Context

Pregnancy- and lactation-associated osteoporosis (PLO) is a rare condition characterized by fragility fractures, mostly vertebral, during the third trimester of pregnancy or the early postpartum period.

Objective

The aim of this study was to evaluate bone microarchitecture in women with PLO to better understand the pathophysiology of this disease.

Methods

In this retrospective study, we included women with PLO referred to our bone center between November 2007 and July 2012. We assessed bone mineral density (BMD) by dual-energy x-ray absorptiometry, bone turnover markers, and bone microarchitecture by high-resolution peripheral quantitative computed tomography. Results were compared with a control group of healthy lactating women.

Results

Of the 7 primiparous patients with PLO, 6 suffered vertebral fractures and 1 developed a hip fracture during the seventh month of gestation. Fractures occurred within the eighth month of pregnancy and the fourth month post partum; vertebral fractures were multiple in 85.7%. Major or minor risk factors for osteoporosis were present in 86% of our patients. Trabecular density, number, and thickness were 34%, 20% and 22% lower than controls (P < .01, P = .01, and P = .01, respectively). Cortical parameters were also deteriorated but to a lesser extent.

Conclusion

In comparison with healthy lactating women, patients with PLO presented severe deterioration of bone trabecular and cortical microarchitecture. This significant compromise may explain the occurrence of multiple fractures in these otherwise healthy young women. Further prospective studies are needed to determine whether bone microarchitecture might be able to be restored in the future.

β-Hydroxy-β-Methylbutyrate (HMB) Supplementation Prevents Bone Loss during Pregnancy-Novel Evidence from a Spiny Mouse (Acomys cahirinus) Model

The aim of this study was to determine the effects of ß-hydroxy-ß-methylbutyrate (HMB) supplementation during pregnancy on postpartum bone tissue quality by assessing changes in trabecular and compact bone as well as in hyaline and epiphyseal cartilage. The experiment was carried out on adult 6-month-old female spiny mice (Acomys cahirinus) divided into three groups: pregnant control (PregCont), pregnant HMB-treated (supplemented with 0.02 g/kg b.w of HMB during the second trimester of pregnancy, PregHMB), and non-pregnant females (NonPreg). Cross-sectional area and cortical index of the femoral mid-shaft, stiffness, and Young modulus were significantly greater in the PregHMB group. Whole-bone mineral density was similar in all groups, and HMB supplementation increased trabecular number. Growth plate cartilage was the thinnest, while the articular cartilage was the thickest in the PregHMB group. HMB supplementation increased the content of proteoglycans in the articular cartilage and the percentage of immature collagen content in metaphyseal trabeculae and compact bone. In summary, dietary HMB supplementation during the second trimester of pregnancy intensifies bone metabolic processes and prevents bone loss during pregnancy.

Effects of Fish Oil and Dietary Antioxidant Supplementation on Bone Health of Growing Lambs

Simple Summary

The current study investigated the bone status of growing lambs fed diets supplemented with bioactive components (fish oil, carnosic acid, SeY, and Na₂SeO₃) improving bone parameters. The study provides new information with regards to the positive role of bioactive components supplemented to diets for growing lambs on their femur characteristics (bone content, bone mineral density, geometry, and strength).

Abstract

The aim of the present study was to assess the effects of partial replacement of rapeseed oil (RO) with fish oil (FO) combined with dietary supplementation of various antioxidants on the characteristics of lamb femur. Thirty male lambs were assigned to five dietary treatments and fed isoproteinous and isoenergetic diets for 35 days. The control diet was enriched with 3.0% RO, while the experimental diets were enriched either only with 2.0% RO and 1.0% FO or additionally with 0.1% carnosic acid, 0.1% carnosic acid and 0.35 ppm Se as selenized yeast, or 0.1% carnosic acid and 0.35 ppm Se as sodium selenite. After 35 days, the lambs were slaughtered, and the femur was dissected from the carcass of each animal and analyzed for morphometric, geometric, densitometric, and biomechanical properties. The dietary modifications, specifically the supplementation of FO and selenized yeast, significantly improved the geometric, densitometric, and biomechanical properties of lamb femur.

Influence of Phytase Supplementation at Increasing Doses from 0 to 1500 FTU/kg on Growth Performance, Nutrient Digestibility, and Bone Status in Grower-Finisher Pigs Fed Phosphorus-Deficient Diets

Simple Summary

The current study investigates the growth performance and bone status of grower–finisher pigs supplemented with phytase, an enzyme which increases the bioavailability of phosphorus in animal feeds. The study results provide new information with regards to the positive role phytase supplementation to livestock feed plays in the achievement of the maximum effectiveness of the feed, as well as numerous positive effects on bone characteristics (geometry, mineralization, and mechanical strength) in grower–finisher pigs.

Abstract

The objective of the current study is to assess the effects of the inclusion of 6-n phytase to a phosphorous-deficient diet on the growth performance (feed intake, average daily gain, and feed conversion ratio), apparent digestibility of calcium and phosphorus, and bone characteristics of grower–finisher pigs. The experimental diets included a phosphorus-deficient diet containing 0 (negative control), 250, 500, 1000, or 1500 FTU/kg of 6-phytase, and a diet formulated to meet the phosphorus nutrient requirements of pigs (positive control). Pigs were fed the experimental diets from the time they were ~35 kg body weight until they reached slaughter weight of ~110 kg. Bone status of the metacarpal (ash, mineral content) and femur (mineralization, geometry, and mechanical strength) bones were assessed. There was no effect of dietary treatment on feed intake. Feed conversion ratio was improved following inclusion of phytase at a dose of 500 FTU/kg or higher. Phytase inclusion at a dose of 1000 FTU/kg increased the average daily weight gain of grower–finisher pigs. Phytase inclusion at a dose of 500 FTU/kg was sufficient to increase metacarpal phosphorus content. Femur mid-diaphysis ash percentage was significantly increased even after the inclusion of the lowest dose of phytase. Analysis of structural parameters of femur mechanical strength (Young’s modulus, yield stress, yield strain, ultimate stress, ultimate strain) showed that the inclusion of a phytase dose of 500 FTU/kg in growing/finishing diets was sufficient to significantly improve bone status of grower–finisher pigs at slaughter.

Effects of Yeast (Saccharomyces Cerevisiae) Probiotics Supplementation on Bone Quality Characteristics in Young Japanese Quail (Coturnix Japonica): The Role of Sex on the Action of the Gut-Bone Axis

Simple Summary

The gastrointestinal tract; as an important mediator of nutrients and elements; regulates bone health. In this study, we examined the effect of supplementation with yeast Saccharomyces cerevisiae on bone characteristics in young Japanese quails. We found that yeast probiotics, through their action on the gut-bone axis, have a positive effect on the structure of articular cartilage and microarchitecture of trabecular bone in young female quails. These data could provide useful information for further research into the supplementation with yeast probiotics aimed to reduce the risk bone fractures during the egg-laying period

Abstract

The aim of the study was to investigate the changes in bone geometry, histological structure, and selected mechanical characteristics in young male and female Japanese quails supplemented with Saccharomyces cerevisiae. Quails were fed a basal diet containing no yeast or a basal diet supplemented with 1.5% (15 g per 1 kg of diet) of inactive S. cerevisiae, for a period of 42 days. S. cerevisiae inclusion had no effect on bone weight, length, and density, diaphysis geometry (cross-sectional area, wall thickness, moment of inertia) or on the mechanical strength (yield load, ultimate load, stiffness, Young’s modulus, yield stress, ultimate stress). Yeast supplementation improved the morphology of the articular cartilage both in male and female quails, as the total thickness of the articular cartilage was significantly increased. In trabecular bone, an increase in real bone volume and trabecular thickness was observed in females supplemented with S. cerevisiae, while in males the increase in trabecular number was accompanied by a reduction in trabecular thickness. The results of the present study demonstrate that S. cerevisiae, through a sex-dependent action on the gut-bone axis, improved the structure of articular cartilage and microarchitecture of trabecular bone. The positive effects of S. cerevisiae supplementation were more evident in female quails.

Biomechanical properties of anuran long bones: correlations with locomotor modes and habitat use

Long bones are subjected to mechanical loads during locomotion that will influence their biomechanical properties through a feedback mechanism (the bone mechanostat). This mechanism adapts the spatial distribution of the mineralized tissue to resist compression, bending and torsion. Among vertebrates, anurans represent an excellent group to study long bone properties because they vary widely in locomotor modes and habitat use, which enforce different skeletal loadings. In this study, we hypothesized that (a) the cortical bone mass, density and design of anuran femur and tibiofibula would reflect the mechanical influences of the different locomotor modes and habitat use, and (b) the relationships between the architectural efficiency of cortical design (cross-sectional moments of inertia) and the intrinsic stiffness of cortical tissue [cortical mineral density; the 'distribution/quality' (d/q) relationship] would describe some inter-specific differences in the efficiency of the bone mechanostat to improve bone design under different mechanical loads. To test this hypothesis, we determined tomographic (peripheral quantitative computed tomography) indicators of bone mass, mineralization, and design along the femur and tibiofibula of four anuran species with different modes of locomotion and use of habitat. We found inter-specific differences in all measures between the distal and proximal ends and mid-diaphysis of the bones. In general, terrestrial-hopper species had the highest values. Arboreal-walker species had the lowest values for all variables except for cortical bone mineral density, which was lowest in aquatic-swimmer species. The d/q relationships showed similar responses of bone modeling as a function of cortical stiffness for aquatic and arboreal species, whereas terrestrial-hoppers had higher values for moments of inertia regardless of the tissue compliance to be deformed. These results provide new evidence regarding the significant role of movement and habitat use in addition to the biomechanical properties of long bones within a morpho-functional and comparative context in anuran species.

Effect of Caponisation on Bone Development in Native Male Chickens

The aim of the study was to determine the effect of caponisation on the morphometric traits and mechanical parameters of tibial and femoral bones in Greenleg Partridge cocks. The experiment involved 200 cocks. At the age of 8 weeks, 100 birds were subjected to surgical castration. At week 24, the birds were slaughtered and tibial and femoral bones were collected from 10 non-caponised cocks and 10 capons. The caponisation surgery had no effect on the weight and length of any of the long bones but resulted in reduction (P≤0.05) of the ash content in both bones and Ca in the femur. It also influenced the geometric structure of the bones, i.e. there was an increase (P≤0.05) in the second moment of inertia in the tibial bone and the cross-sectional area and mean relative wall thickness in the femoral bone of the capons. The three-point bending test revealed a negative effect of caponisation on the mechanical strength of the bone. Values characterising the highest bone material strength, i.e. yielding load (femur), maximum force moment (tibia) and yielding deformation, bending point resistance, and load-to-deformation (both bones), declined in the capons. The investigations demonstrated a negative effect of caponisation on the quality of long bones. The tibial bone seems to be slightly more sensitive to the caponisation effects than the femoral bone. It can be assumed based on the analysis of biomechanical traits that the bones of capons are more susceptible to deformations or fractures due to their modified geometry and mechanical brittleness.

Retention of osteocytic micromorphology by sclerostin antibody in a concurrent ovariectomy and functional disuse model

Prolonged mechanical unloading in bedridden patients and concurrent hormonal dysregulation represents the cause of one of the severest forms of osteoporosis, a condition for which there are very few efficacious interventions available to date. Sclerostin, a Wnt antagonist, acts as a negative regulator of bone formation. Sclerostin antibody (Scl-Ab)-mediated blockade of sclerostin can dramatically enhance bone formation and reduce bone resorption. This study was designed to investigate the therapeutic effect of the Scl-Ab on severe bone loss induced by concurrent mechanical unloading and estrogen deficiency in a hindlimb-suspended and ovariectomized rat model, and to study the cellular mechanisms underlying severe osteoporosis and Scl-Ab action. Unloading and ovariectomy resulted in severe loss of trabecular and cortical bone mass and strength; Scl-Ab can significantly counteract the deterioration of bone in unloaded and/or ovariectomized rats, with noticeably increased cortical bone formation. Scanning electron microscopy analysis revealed that unloading and ovariectomy lead to multiple morphological and structural abnormalities of osteocytes in cortical bone and the abnormalities were abolished by Scl-Ab administration. This study extends our previous conclusion that Scl-Ab represents a promising therapeutic approach for severe bone loss that occurs after being exposed to estrogen deficiency and prolonged mechanical unloading.

Dietary n-3 PUFA content as a modulator of the femur properties in growing pigs

The relationships between both dietary and empty body fatty acid composition and the morphometry, densitometry, geometry and biomechanical properties of the femur of growing pigs were analysed. A total of thirty-two pigs aged 115 d were divided into four groups (n 8 per group). The pigs were fed either a control diet (group C) or a diet supplemented with linseed oil (rich in α-linolenic acid (C18 : 3n-3), group L), fish oil (rich in EPA (C20 : 5n-3) and DHA (C22 : 6n-3), group F) and beef tallow (rich in SFA, group T). The diets differed in n-3 PUFA contents (0·63-18·52 g/kg) and n-6:n-3 PUFA ratios (0·91-14·51). At 165 d of age, the pigs were slaughtered and the fatty acids in the empty body were determined. Moreover, the left femur was dissected. The cortical wall thickness, cross-sectional area, cortical index, bone mineral content, bone mineral density, maximum elastic strength and maximum strength were lower (P<0·05) in the femurs of pigs from groups C and T than in those from groups F and L. Significant positive correlations were found between the densitometry, geometry and biomechanical properties of the femur and both dietary and empty body n-3 PUFA content, whereas significant negative correlations were observed between the same properties and both dietary and empty body n-6:n-3 PUFA ratio. The results of the present study suggest that in growing pigs α-linolenic acid has a similar positive effect on bone health to that of EPA and DHA.

Interrelationships Between Morphometric, Densitometric, and Mechanical Properties of Teeth in 5-Month-Old Polish Merino Sheep

Interrelationships between morphological, densitometric, and mechanical properties of deciduous mandibular teeth (incisors, canine, second premolar) were investigated. To perform morphometric, densitometric, and mechanical analyses, teeth were obtained from 5-month-old sheep. Measurements of mean volumetric tooth mineral density and total tooth volume were performed using quantitative computed tomography. Microcomputed tomography was used to measure total enamel volume, volumetric enamel mineral density, total dentin volume, and volumetric dentin mineral density. Maximum elastic strength and ultimate force of teeth were determined using 3-point bending and compression tests. Pearson correlation coefficients were determined between all investigated variables. Mutual dependence was observed between morphological and mechanical properties of the investigated teeth. The highest number of positive correlations of the investigated parameters was stated in first incisor indicating its superior predictive value of tooth quality and masticatory organ function in sheep. Positive correlations of the volumetric dentin mineral density in second premolar with final body weight may indicate predictive value of this parameter in relation with growth rate in sheep. Evaluation of deciduous tooth properties may prove helpful for breeding selection and further reproduction of sheep possessing favorable traits of teeth and better masticatory organ function, leading to improved performance and economic efficiency of the flock.

Inulin supplementation reduces the negative effect of a high-fat diet rich in SFA on bone health of growing pigs

Consumption of a high-fat diet, rich in SFA, causes deterioration of bone properties. Some studies suggest that feeding inulin to animals may increase mineral absorption and positively affect bone quality; however, these studies have been carried out only on rodents fed a standard diet. The primary objective of this study was to determine the effect of inulin on bone health of pigs (using it as an animal model for humans) fed a high-fat diet rich in SFA, having an unbalanced ratio of lysine:metabolisable energy. It was hypothesised that inulin reduces the negative effects of such a diet on bone health. At 50 d of age, twenty-one pigs were randomly allotted to three groups: the control (C) group fed a standard diet, and two experimental (T and TI) groups fed a high-fat diet rich in SFA. Moreover, TI pigs consumed an extra inulin supply (7 % of daily feed intake). After 10 weeks, whole-body bone mineral content (P=0·0054) and bone mineral density (P=0·0322) were higher in pigs of groups TI and C compared with those of group T. Femur bone mineral density was highest in pigs in group C, lower in group TI and lowest in group T (P=0·001). Femurs of pigs in groups TI and C had similar, but higher, maximum strength compared with femurs of pigs in group T (P=0·0082). In conclusion, consumption of a high-fat diet rich in SFA adversely affected bone health, but inulin supplementation in such a diet diminishes this negative effect.

Evaluation of the anti-osteoporotic effect of Ginkgo biloba L. in Wistar rats with glucocorticoid-induced-osteoporosis by bone densitometry using dual-energy x-ray absorptiometry (DEXA) and mechanical testing

Evaluate the effect of the extract of Ginkgo biloba in the bone alkaline phosphatase, bone mineral density, in the mechanical properties of the tibia in rats with glucocorticoid-induced-osteoporosis. After osteoporosis induction, the rats were divided into five groups: Osteoporosis; EGb1 (28 mg/Kg); EGb2 (56 mg/Kg); alendronate (0.2 mg/animal) and control. The animals were treated during 20 and 30 days. The control group was compared with the osteoporosis's (Student's t-test), while the other were analyzed by ANOVA test followed by Tukey/Dunnett'T3 (p<0.05). In the osteoporosis group the bone alkaline phosphatase, bone mineral density, the bone stiffness, the maximum load and the resilience were reduced. The bone alkaline phosphatase values increased in the EGb1 and EGb2 groups (30 days). In addition, in the EGb2 and alendronate groups (20 and 30 days) the bone mineral density increased. The extract of Ginkgo biloba restored bone alkaline phosphatase and bone mineral density using dual-energy x-ray absorptiometry.

DON-induced Changes in Bone Homeostasis in Mink Dams

Introduction

The aim of the study was to investigate the mechanical and geometric properties as well as bone tissue and mineral density of long bones in mink dams exposed to deoxynivalenol (DON) since one day after mating, throughout gestation (ca. 46 d) and lactation to pelt harvesting.

Material and Methods

Thirty clinically healthy multiparous minks (Neovison vison) of the standard dark brown type were used. After the mating, the minks were randomly assigned into two equal groups: non-treated control group and DON group fed wheat contaminated naturally with DON at a concentration of 1.1 mg·kg^-1 of feed.

Results

The final body weight and weight and length of the femur did not differ between the groups. However, DON contamination decreased mechanical endurance of the femur. Furthermore, DON reduced the mean relative wall thickness and vertical wall thickness of the femur, while vertical cortical index, midshaft volume, and cross-sectional moment of inertia increased. Finally, DON contamination did not alter bone tissue density, bone mineral density, or bone mineral content, but decreased the values of all investigated structural and material properties.

Conclusion

DON at applied concentration probably intensified the process of endosteal resorption, which was the main reason for bone wall thinning and the weakening of the whole bone.

The Influence of the Dietary Cu-Glycine Complex on the Histomorphology of Cancellous Bone, Articular Cartilage, and Growth Plate as well as Bone Mechanical and Geometric Parameters Is Dose Dependent

Copper (Cu) is required for all basic biochemical and physiological processes. The objective of this study was to compare the effect of two different chemical forms (sulfates and glycinate chelates also below the recommended dose) of Cu administered to adult rats on the biomechanical and morphometric properties of femur. Male rats at the age of 12 weeks were used in the 12-week experiment. The control diet provided the required Cu level from sulfate (S-Cu), and the other diets were supplemented with Cu-glycine complex. The Cu-Gly-treatment, irrespective of its concentration, did not influence the bone mass and length. The Cu-Gly-treatment in 100 and 75% of daily demand increased mechanical endurance. The Cu-Gly-treatment (regardless of its concentration) increased the real bone volume in epiphysis and decreased the total thickness and zone I of the articular cartilage compared to the control group supplemented with S-Cu. The Cu-Gly-treatment enhanced the content of proteoglycans (except the OG50 group). Dietary Cu given to adult rats in the Cu-Gly complex covering the daily demand in 75% exerted a positive effect on bone metabolism and appeared to be the most effective among the investigated doses of the organic form.

Morphological, densitometric and mechanical properties of mandible in 5-month-old Polish Merino sheep

BACKGROUND

Among bones building the axial and appendicular skeleton, the mandible is characterized by unique morphological and functional traits. The aim of the study was to evaluate morphological, densitometric and mechanical properties of mandible in 5-month-old Polish Merino sheep. Using quantitative computed tomography, volumetric bone mineral density (vBMD) and calcium hydroxyapatite density of the cortical bone (CbCa-HA), mean vBMD (MvBMD) and total bone volume were determined. Using computed tomography cross-sectional scans of the mandible, cross-sectional area, second moment of inertia, mean relative wall thickness and cortical index were determined. Three-point bending test was applied to determine mechanical properties. Serum concentration of insulin-like growth factor I (IGF-I) and bone-specific alkaline phosphatase (BAP) was also measured.

RESULTS

All the investigated morphometric, densitometric and mechanical parameters of the right and left mandibular halves were not significantly different (P > 0.05). There was no correlation of final body weight, MvBMD, CbCa-HA, BAP and IGF-I with all the analyzed parameters of mandible (P > 0.05). However, positive correlations between the other investigated morphometric, densitometric and mechanical parameter of mandible were found (P < 0.05).

CONCLUSIONS

Relationships between morphological, densitometric and mechanical parameters of the mandible indicate that the elaborated experimental model may serve for further studies on metabolic responses of skeletal system to physiological, nutritional, pharmacological, toxicological and environmental factors.

Fundectomy-Evoked Osteopenia in Pigs Is Mediated by the Gastric-Hypothalamic-Pituitary Axis

The aim of the study was to determine the effects of gastric impairment in pigs on the axial and peripheral skeletal system properties and to test the hypothesis that fundectomy-evoked osteopenia is related to disturbed gastric-hypothalamic-pituitary axis function. Forty-day-old male piglets were subjected to experimental fundectomy (FX group, n = 6) to induce osteopenia, while sham operation was performed in the controls (SHO group, n = 6). At the age of 8 months, serum samples were collected, and the animals were sacrificed to obtain lumbar vertebrae (L1–L6) and right humerus for analysis. Using quantitative computed tomography (QCT) and dual-energy x-ray absorptiometry (DEXA) methods, bone mineral density and bone mineral content of the vertebrae and humerus were measured. The compression and three-point bending tests were applied to determine mechanical properties of lumbar vertebrae and humerus, respectively. Furthermore, geometric properties of humerus were assessed. Serum concentrations of ghrelin, growth hormone (GH), insulin-like growth factor-1 (IGF-1), and selected macro- and microelements were also determined. Performed fundectomy decreased body weight in pigs by 66% compared with pair-fed sham operated pigs ( P < 0.0001). Bone weight, bone mineral density, and bone mineral content of the lumbar vertebrae and humerus were significantly decreased in the fundectomized pigs ( P < 0.01). Mechanical parameters of the lumbar spine and humerus were decreased after the fundectomy, as well. Serum concentrations of ghrelin, GH, and IGF-1 were lowered by 74.4%, 90.6%, and 54.6% in the fundectomized pigs, respectively (all P < 0.001). Moreover, the serum concentrations of calcium, magnesium, iron and copper in the fundectomized animals were significantly decreased by 15.5%, 45.3%, 26.7%, and 26.2%, respectively ( P ≤ 0.05). In conclusion, the results obtained showed that both the disturbed gastric-hypothalamic-pituitary axis function and impaired mineral metabolism are associated with development of postfundectomy osteopenia of axial and peripheral skeleton in pigs.

Effect of simvastatin on osteogenesis of the lumbar vertebrae in ovariectomized rats

The aim of the present study was to assess the role of simvastatin on osteoporosis of the vertebrae by examining the effect of simvastatin on the osteogenesis of the lumbar vertebra in ovariectomized (OVX) rats. A total of 60 6-month-old female Sprague Dawley rats were divided into one sham group and five ovariectomized groups, consisting of four simvastatin groups and one control group. Four dosages of simvastatin (5, 10, 20 and 40 mg/kg/d) were administered by gavage for three months. L4 vertebrae were examined by dual-energy X-ray absorptiometry (DEXA) and peripheral quantitative computed tomography (pQCT) to determine the mineral apposition rate (MAR). L5 vertebrae were examined using a compression biomechanical test. Although the measurements from DEXA, pQCT and MAR, and the biomechanical parameters in the OVX + simvastatin rats were higher than those for the OVX + vehicle group, no significant differences were detected. Therefore, simvastatin may not improve osteogenesis of the lumbar vertebra in OVX rats or prevent osteoporosis of the spinal vertebrae.

Morphological, densitometric and mechanical properties of pelvic limb bones in 14-month-old female ostriches (Struthio camelus)

Limited information on physiological characteristic of bones in ostrich skeleton are available, even though bone weaknesses in ostriches are commonplace. Thus, the aim of this study was to evaluate morphological, densitometric, and mechanical properties of pelvic limb long bones (femur, tibia, and tarsometatarsus) in 14-month-old female ostriches (Struthio camelus var. domesticus). After the slaughter procedure, all bones were isolated, cleaned of soft tissues, and bone weight and length were determined. Using dual energy X-ray absorptiometry (DEXA) bone mineral density (BMD) and bone mineral content (BMC) were determined. Volumetric bone mineral density (vBMD) and geometrical parameters of the bones were determined using the quantitative computed tomography (QCT) method. Maximum elastic strength and ultimate strength of the bones were determined using three-point bending test. Significant differences were revealed between morphological, densitometric, and mechanical properties of femur, tibia, and tarsometatarsus in female ostriches at the slaughter age of 14 months. Elaborated experimental model and determination of morphological, densitometric, and mechanical properties of femur, tibia, and tarsometatarsus in female ostriches may serve for further studies on metabolic regulation of skeletal system properties with environmental, physiological, dietary, pharmacological, and toxicological factors.

Bentonite diminishes DON-induced changes in bone development in mink dams

Introduction: The aim of this study was to determine the effect of deoxynivalenol (DON), given alone or with bentonite (which eliminates mycotoxicity) in the diet of mink dams throughout mating, pregnancy, and lactation period to pelt harvesting, on the mechanical properties and geometry of their long bones.

Material and Methods: The minks were randomly assigned into two groups: a control group (not supplemented with DON, n = 15) and a group fed naturally DON-contaminated wheat and divided into three sub-groups (each sub-group n = 15), depending on bentonite dose: 0 M – sub-group fed naturally DON-contaminated wheat at a concentration of 3.7 mg kg−1 alone; 2 M – sub-group fed naturally DON-contaminated wheat at a concentration of 3.7 mg kg−1 and bentonite at a concentration of 2 kg 1000 kg−1; 0.5 M – sub-group fed naturally DON-contaminated wheat at a concentration of 3.7 mg kg−1 and bentonite at a concentration of 0.5 kg 1000 kg−1.

Results: The DON treatment reduced the length of the femur compared to the control group and reduced the bone weight dependently on the amount of bentonite supplementation. However, DON treatment reduced the MRWT and CI of the femur, irrespective of the bentonite supplementation, compared to the control. The total BTD and BMC decreased in all DON-treated groups (irrespective of the bentonite supplementation). Furthermore, the densitometric analysis showed that the main changes in BMD and BMC indicated bone loss in the proximal and distal parts of bone covering the trabecular bone; whereas when bentonite was given at the dose of 2 kg 1000 kg−1 an increase in the whole BMD and BMC was observed in the femoral midshaft.

Conclusion: Analysis of the geometrical parameters seems to indicate that endosteal resorption was delayed after bentonite supplementation. The addition of bentonite diminished the DON action on bone homeostasis in the mink dams. Thus bentonite could prevent DON-induced bone loss in a dose-dependent manner.

Dual-energy X-ray absorptiometry, peripheral quantitative computed tomography, and micro-computed tomography techniques are discordant for bone density and geometry measurements in the guinea pig

This study aims to examine agreement among bone mineral content (BMC) and density (BMD) estimates obtained using dual-energy X-ray absorptiometry (DXA), peripheral quantitative computed tomography (pQCT), and micro-computed tomography (μCT) against high-resolution μCT and bone ash of the guinea pig femur. Middle-aged (n = 40, 86 weeks) male guinea pigs underwent in vivo followed by ex vivo DXA (Hologic QDR 4500A) scanning for intact and excised femur BMC and areal density. To assess bone architecture and strength, excised femurs were scanned on pQCT (Stratec XCT 2000L) as well as on two μCT scanners (LaTheta LCT-200; Skyscan 1174), followed by three-point bending test. Reproducibility was determined using triplicate scans; and agreement assessed using Bland-Altman plots with reference methods being high-resolution μCT (Skyscan) for BMD and bone ashing for BMC. All techniques showed satisfactory ex vivo precision (CV 0.05-4.3 %). However, bias compared to the reference method was highest (207.5 %) in trabecular bone volume fraction (BV/TV) measured by LaTheta, and unacceptable in most total femur and cortical bone measurements. Volumetric BMD (vBMD) and BV/TV derived by LaTheta and pQCT at the distal metaphysis were biased from the Skyscan by an average of 49.3 and 207.5 %, respectively. Variability of vBMD, BV/TV and cross-sectional area at the diaphysis ranged from -5.5 to 30.8 %. LaTheta best quantified total femur BMC with an upper bias of 3.3 %. The observed differences among imaging techniques can be attributable to inherent dissimilarity in construction design, calibration, segmentation and scanning resolution used. These bone imaging tools are precise but are not comparable, at least when assessing guinea pig bones.

Effect of chronic undernutrition on body mass and mechanical bone quality under normoxic and altitude hypoxic conditions

Both undernutrition and hypoxia exert a negative influence on both growth pattern and bone mechanical properties in developing rats. The present study explored the effects of chronic food restriction on both variables in growing rats exposed to simulated high-altitude hypoxia. Male rats (n 80) aged 28 d were divided into normoxic (Nx) and hypoxic (Hx) groups. Hx rats were exposed to hypobaric air (380 mmHg) in decompression chambers. At T0, Nx and Hx rats were subdivided into four equal subgroups: normoxic control and hypoxic controls, and normoxic growth-restricted and hypoxic growth-restricted received 80 % of the amount of food consumed freely by their respective controls for a 4-week period. Half of these animals were studied at the end of this period (T4). The remaining rats in each group continued under the same environmental conditions, but food was offered ad libitum to explore the type of catch-up growth during 8 weeks. Structural bone properties (strength and stiffness) were evaluated in the right femur midshaft by the mechanical three-point bending test; geometric properties (length, cross-sectional area, cortical mass, bending cross-sectional moment of inertia) and intrinsic properties of the bone tissue (elastic modulus) were measured or derived from appropriate equations. Bone mineralisation was assessed by ash measurement of the left femur. These data indicate that the growth-retarded effects of diminished food intake, induced either by food restriction or hypoxia-related inhibition of appetite, generated the formation of corresponding smaller bones in which subnormal structural and geometric properties were observed. However, they seemed to be appropriate to the body mass of the animals and suggest, therefore, that the bones were not osteopenic. When food restriction was imposed in Hx rats, the combined effects of both variables were additive, inducing a further reduction of bone mass and bone load-carrying capacity. In all cases, the mechanical properties of the mineralised tissue were unaffected. This and the capacity of the treated bones to undergone complete catch-up growth with full restoration of the biomechanical properties suggest that undernutrition, under either Nx or Hx conditions, does not affect bone behaviour because it remains appropriate to its mechanical functions.

Correlation Between Stress Distributions and Biological Reactions in Bone Surrounding Implants That Support Cantilevers in Supraocclusal Contact in Rats

PURPOSE

To investigate the relationship between stress distributions and peri-implant bone reactions around maxillary implants that support cantilevers in supraocclusal contact.

MATERIALS AND METHODS

After molar extraction, 16 Wistar rats received a titanium implant unilaterally. After healing, 8 rats (control group) were killed and the others received implant-supported cantilever superstructures in supraocclusion (loaded group). After 5 days, they were killed. The maxillae of all rats were scanned by microcomputed tomography (μ-CT). Based on the μ-CT images, bone volumes were measured. For the loaded group, 3D finite element models were created and analyzed under 20-N vertical and 5-N lateral forces, successively. After μ-CT scanning, sections were prepared and observed histologically.

RESULTS

When compared with the controls, the bone volume tended to decrease in the loaded group, but the difference was not statistically significant. On average, marginal bone resorption and stresses tended to be higher in 2 rats that occluded on the cantilever arm than in the others, which occluded right on the implant, nevertheless, calculated stress did not surpass the maximum elastic stress (yielding strength) of rat bone. However, at the implant-bone interface of these samples, partial bone resorption surrounded by signs of active resorption was histologically found.

CONCLUSION

These findings suggest that in this occlusally loaded rat model, the stress distributions correlated to some extent with bone volume and morphological changes observed on μ-CT images and histological sections.

Static biomechanics in bone from growing rats exposed chronically to simulated high altitudes

Biomechanical behavior of bone is related to the amount (bone mass) and its architectural distribution, as well as the mechanical quality of bone material. This investigation reports the effects of exposure to different simulated high altitudes (SHA) (1850, 2900, 4100, and 5450 m) on femur biomechanical properties in female growing rats exposed to SHA (22-23 h/d) between the 32° and the 74° days of life. The ex vivo right femur was mechanically tested in three-point bending. The left femur was ashed at 600°C and the ash weight obtained. Final body weight and structural (loads at yielding and fracture, stiffness, and elastic energy absorption) and architectural (diaphyseal cross-sectional area, cortical area, and cross-sectional moment of inertia) were negatively affected in the animals exposed to the two highest SHA. Material properties of the mineralized tissue (Young's modulus and limit elastic stress) and the degree of mineralization were unaffected. In conclusion, hypoxic bone is weaker than normoxic one because of its smaller bone mass, which appear to have been negatively influenced by SHA in relation to its effects on overall body mass.

Sex-related differences of morphometric, densitometric, and geometric parameters of tibia and tarsometatarsal bone in 14-month-old ostriches (Struthio camelus)

The aim of the current study was to investigate basic morphometric, geometric, and densitometric parameters of tibia and tarsometatarsus in 14-mo-old male and female ostriches, and interrelationships between these parameters. The study was conducted on 20 tibiae and 20 tarsometatarsal bones of the left pelvic limb derived from 20 healthy 14-mo-old ostriches (Struthio camelus): 10 males and 10 females. The following parameters were determined using peripheral quantitative computed tomography: bone mineral content (BMC), volumetric bone mineral density (vBMD), cortical content (CRT_CNT), cortical density (CRT_DEN), trabecular content, trabecular density (TRAB_DEN), bone area (TOT_A), trabecular area (TRAB_A), cortical area (CRT_A), cortical thickness (CRT_THK_C), periosteal circumference (PERI_C), endocortical circumference (ENDO_C), and strength-strain index (SSI) in the metaphysis and diaphysis of the bones. Statistical evaluation of the obtained results was performed using Student's t-test, and the Pearson correlation coefficient between the investigated parameters was determined. The obtained results have shown significant differences in proximal metaphysis between males and females when evaluating such parameters as CRT_DEN, TOT_A, TRAB_A, PERI_C, SSI in tibia (P < 0.05), and BMC, vBMD, TRAB_DEN, CRT_CNT, TOT_A, TRAB_A, cortical area, PERI_C, ENDO_C, SSI in tarsometatarsus (P < 0.05). Significant differences between the 2 sexes were found in all the investigated parameters of diaphysis of tibia, except for CRT_DEN and ENDO_C (P < 0.05). Significant positive correlations between BW and bone weight were found (P < 0.05). Furthermore, numerous correlations of morphometric, geometric, and densitometric parameters of metaphysis and diaphysis of the tibia and tarsometatarsus were stated (P < 0.05). In conclusion, the present investigation demonstrated sex-related differences in morphometric, densitometric, and geometric properties of tibia and tarsometatarsus in 14-mo-old ostriches. Numerous correleations observed between the investigated parameters have shown that ostrich tibia and tarsometatarsus may present a valuable model for further studies on bone tissue metabolism regulation in breeding birds.

Mechanical testing at the whole-bone level of the femur in immature rats stunted by cornstarch consumption

Both body weight and somatic muscle forces are the main "mechanical factors" in the determination of bone strength in the "weight-bearing bones". However, other "non-mechanical factors", such as dietary proteins, also exist, which modulate bone physiology. This study was designed to explore the mechanical behavior of the femur in post-weaning female rats stunted by feeding on cornstarch. Forty female rats aged 30 days were fed freely with one of the two diets: control (CD) and experimental (ED). CD was the standard rat laboratory diet, whereas ED was cornstarch supplemented with vitamins and minerals. Control (C) and experimental (E) animals were divided into 4 groups: C40 and E40 rats were given CD and ED, respectively, for 40 days; C105 were fed the CD for 105 days; and E40-105 were given the ED for 40 days and then the CD for the remaining experimental period (65 days). Growth of rats was assessed following Parks' model. The biomechanical structural properties of the right femur middiaphysis were estimated using a 3-point bending test. The geometric properties of both the entire bone and the cross-section were determined. The left femur was ashed and both the Ca mass and the Ca concentration were determined. Rats fed the ED failed to achieve normal weight gain. Complete catch-up was observed at the end of a 65 day period of nutritional rehabilitation. The femoral weight and length were negatively affected by the ED, as were the mid-diaphyseal cross-sectional area, the mineralized cortical area, and the cross-sectional moment of inertia. All of these parameters showed incomplete catch-up. The structural bone mechanical properties indicative of strength and stiffness were seriously negatively affected. Intrinsic material bone properties, as assessed by the modulus of elasticity and the maximal elastic stress, were within normal values. In summary, the experimental bone was weaker than the control and structurally incompetent. The considered bone was smaller than the control one, showing a significant reduction in the cross-sectional area and the moment of inertia. However, material properties as well as the ash fraction and Ca concentration were similar in E and C bones. Therefore, E bone is weaker than the C one because of its smaller bone mass, which appears to have been negatively influenced by the ED in relation to its effects on overall body mass.

Functional integration of skeletal traits: an intraskeletal assessment of bone size, mineralization, and volume covariance

Understanding the functional integration of skeletal traits and how they naturally vary within and across populations will benefit assessments of functional adaptation directed towards interpreting bone stiffness in contemporary and past humans. Moreover, investigating how these traits intraskeletally vary will guide us closer towards predicting fragility from a single skeletal site. Using an osteological collection of 115 young adult male and female African-Americans, we assessed the functional relationship between bone robustness (i.e. total area/length), cortical tissue mineral density (Ct.TMD), and cortical area (Ct.Ar) for the upper and lower limbs. All long bones demonstrated significant trait covariance (p < 0.005) independent of body size, with slender bones having 25-50% less Ct.Ar and 5-8% higher Ct.TMD compared to robust bones. Robustness statistically explained 10.2-28% of Ct.TMD and 26.6-64.6% of Ct.Ar within male and female skeletal elements. This covariance is systemic throughout the skeleton, with either the slender or robust phenotype consistently represented within all long bones for each individual. These findings suggest that each person attains a unique trait set by adulthood that is both predictable by robustness and partially independent of environmental influences. The variation in these functionally integrated traits allows for the maximization of tissue stiffness and minimization of mass so that regardless of which phenotype is present, a given bone is reasonably stiff and strong, and sufficiently adapted to perform routine, habitual loading activities. Covariation intrinsic to functional adaptation suggests that whole bone stiffness depends upon particular sets of traits acquired during growth, presumably through differing levels of cellular activity, resulting in differing tissue morphology and composition. The outcomes of this intraskeletal examination of robustness and its correlates may have significant value in our progression towards improved clinical assessments of bone strength and fragility.

Identification of gender-specific candidate genes that influence bone microarchitecture in chromosome 1

Studies on the identification of the genetic basis for sexual dimorphism in peak bone mass are obviously important for providing novel therapeutic approaches to prevent or treat metabolic bone diseases. Our goal in this study was to identify the bone microstructure that could lead to differences in volumetric bone mineral density (vBMD) and new candidate genes that regulate the gender effect on bone. We used a congenic line of mice that carry the BMD1-4 locus from CAST/EiJ (CAST) mice in a C57BL/6J (B6) background and show greater vBMD in female, but not male, congenics compared to age- and gender-matched B6 mice. To assess the vBMD variations between the two lines of mice, we performed μCT measurements and found no difference in cortical bone volume by tissue volume (BV/TV) between congenics and B6 mice. However, trabecular BV/TV was significantly greater in female, but not male, congenics compared to corresponding B6 mice, which was due to increased trabecular thickness but not reduced trabecular separation, suggesting that bone formation, but not bone resorption, is responsible for the trabecular bone phenotype observed in the female, but not male, congenics. To identify the gender candidate genes, we determined the polymorphisms between B6 and CAST within the BMD1-4 locus and performed gene expression profiling. We identified EF-hand calcium binding domain (Efcab2), consortin, connexin sorting protein (Cnst), and presenilin 2 (Psen2) as potential candidate genes that regulate bone mass by influencing trabecular thickness in a gender-specific manner.

The influence of follistatin on mechanical properties of bone tissue in growing mice with overexpression of follistatin

Mechanical competence of bones is mainly associated with tissue quality that depends on proper bone metabolism processes. An imbalance in the regulation of bone metabolism leads to pathological changes in bone tissue leading to susceptibility to bone fractures and bone deterioration processes. Bone metabolism is regulated to a large extent by the members of the transforming growth factor-β superfamily, i.e., activins and bone morphogenetic proteins. However, their function is regulated by a single-chain protein called follistatin (FS). The aim of this study was to test the hypothesis that overexpression of FS in growing mice results in impairments in bone morphology and mechanical properties. Moreover, we wanted to investigate how geometrical, structural and material properties of bone tissue change with age. The experiment was performed on growing C57BL/6 TgNK14-mFst/6J mice, overexpressing FS (F mice) versus C57BL/6J mice used as controls (C mice). To establish how overexpression of FS influences bone tissue quality, we studied mice femurs to determine geometrical, structural and material properties of the skeleton. To determine mechanical resistance of bone tissue, femurs were loaded to failure in a three-point bending test. Obtained results indicated that overexpression of FS negatively influences bone metabolism. It was found that mutation results with a significant decrease of all measured biomechanical strength variables in F mice in comparison to C mice. Overexpression of FS leads to decreased quality of skeleton, increasing susceptibility to bone fractures.

Effect of hyperlipidemia on femoral biomechanics and morphology in low-density lipoprotein receptor gene knockout mice

The objective of this study was to evaluate the effect of hyperlipidemia on the biomechanical and morphological properties of the femur of low-density lipoprotein receptor gene knockout mice (LDLr-/-) mice. Ten wild-type mice (C57BL6) and 10 LDLr-/- mice generated on a C57BL6 background were used. Male 3-month-old animals were divided into four groups (n = 5): group W (wild type) and group L (LDLr-/-) receiving low-fat commercial ration, and group WH (wild type) and group LH (LDLr-/-) receiving a high-fat diet. After 60 days, blood samples were collected for laboratory analysis of calcium, triglycerides, and cholesterol. The femur was excised for mechanical testing and morphometric analysis. LDLr-/- mice receiving the high-fat diet presented more marked alterations in the mechanical and morphological properties of femoral cortical and trabecular bone. Changes in the plasma levels of calcium, triglycerides, cholesterol, and fractions were also more pronounced in this group. The present results demonstrate that hyperlipidemia causes alterations in the structure and mechanical properties of the femur of LDLr-/- mice. These effects were more pronounced when associated with a high-fat diet.

Effects of combined maternal administration with alpha-ketoglutarate (AKG) and β-hydroxy-β-methylbutyrate (HMB) on prenatal programming of skeletal properties in the offspring

BACKGROUND

Nutritional manipulations during fetal growth may induce long-term metabolic effects in postnatal life. The aim of the study was to test whether combined treatment of pregnant sows with alpha-ketoglutarate and β-hydroxy-β-methylbutyrate induces additive long-term effects on skeletal system properties in the offspring.

METHODS

The study was performed on 290 pigs obtained from 24 sows divided into 4 equal groups and subjected to experimental treatment during two weeks before delivery. The first group consisted of control sows, while the second group received alpha-ketoglutarate. The third group was treated with β-hydroxy-β-methylbutyrate and the fourth group underwent combined administration of alpha-ketoglutarate and β-hydroxy-β-methylbutyrate. Piglets obtained from sows were reared until slaughter age to perform morphometric, densitometric and mechanical analyses of femur. Serum evaluations of growth hormone, insulin-like growth factor-1, bone-specific alkaline phosphatase and osteocalcin were performed in newborns and 90-day old piglets; additionally, plasma amino acid concentration was measured in newborns.

RESULTS

Maternal treatment with alpha-ketoglutarate and β-hydroxy-β-methylbutyrate significantly reduced fattening time and increased birth body weight, daily body weight gain, bone weight, volumetric bone mineral density, geometrical parameters and mechanical endurance of femur. These effects were associated with increased serum concentrations of growth hormone, insulin-like growth factor-1, bone-specific alkaline phosphatase and osteocalcin. Furthermore, alpha-ketoglutarate and β-hydroxy-β-methylbutyrate administered solely or in combination significantly increased plasma level of 19 amino acids.

CONCLUSIONS

Hormonal and amino acid evaluations in pigs indicate additive effects of AKG and HMB on systemic growth and development; however, determination of bone properties has not shown such phenomenon.