Mmp2 Deficiency Leads to Defective Parturition and High Dystocia Rates in Mice.

Parturition is the final and essential step for mammalian reproduction. While the uterus is quiescent during pregnancy, fundamental changes arise in the myometrial contractility, inducing fetal expulsion. Extracellular matrix (ECM) remodeling is fundamental for these events. The gelatinases subgroup of matrix metalloproteinases (MMPs), MMP2 and MMP9, participate in uterine ECM remodeling throughout pregnancy and parturition. However, their loss-of-function effect is unknown. Here, we determined the result of eliminating Mmp2 and/or Mmp9 on parturition in vivo, using single- and double-knockout (dKO) mice. The dystocia rates were measured in each genotype, and uterine tissue was collected from nulliparous synchronized females at the ages of 2, 4, 9 and 12 months. Very high percentages of dystocia (40-55%) were found in the Mmp2-/- and dKO females, contrary to the Mmp9-/- and wild-type females. The histological analysis of the uterus and cervix revealed that Mmp2-/- tissues undergo marked structural alterations, including highly enlarged myometrial, endometrial and luminal cavity. Increased collagen deposition was also demonstrated, suggesting a mechanism of extensive fibrosis in the Mmp2-/- myometrium, which may result in dystocia. Overall, this study describes a new role for MMP2 in myometrium remodeling during mammalian parturition process, highlighting a novel cause for dystocia due to a loss in MMP2 activity in the uterine tissue.

A novel nonosteocytic regulatory mechanism of bone modeling.

Osteocytes, cells forming an elaborate network within the bones of most vertebrate taxa, are thought to be the master regulators of bone modeling, a process of coordinated, local bone-tissue deposition and removal that keeps bone strains at safe levels throughout life. Neoteleost fish, however, lack osteocytes and yet are known to be capable of bone modeling, although no osteocyte-independent modeling regulatory mechanism has so far been described. Here, we characterize a novel, to our knowledge, bone-modeling regulatory mechanism in a fish species (medaka), showing that although lacking osteocytes (i.e., internal mechanosensors), when loaded, medaka bones model in mechanically directed ways, successfully reducing high tissue strains. We establish that as in mammals, modeling in medaka is regulated by the SOST gene, demonstrating a mechanistic link between skeletal loading, SOST down-regulation, and intense bone deposition. However, whereas mammalian SOST is expressed almost exclusively by osteocytes, in both medaka and zebrafish (a species with osteocytic bones), SOST is expressed by a variety of nonosteocytic cells, none of which reside within the bone bulk. These findings argue that in fishes (and perhaps other vertebrates), nonosteocytic skeletal cells are both sensors and responders, shouldering duties believed exclusive to osteocytes. This previously unrecognized, SOST-dependent, osteocyte-independent mechanism challenges current paradigms of osteocyte exclusivity in bone-modeling regulation, suggesting the existence of multivariate feedback networks in bone modeling-perhaps also in mammalian bones-and thus arguing for the possibility of untapped potential for cell targets in bone therapeutics.

Nutritional Approaches as a Treatment for Impaired Bone Growth and Quality Following the Consumption of Ultra-Processed Food.

The severe impairment of bone development and quality was recently described as a new target for unbalanced ultra-processed food (UPF). Here, we describe nutritional approaches to repair this skeletal impairment in rats: supplementation with micro-nutrients and a rescue approach and switching the UPF to balanced nutrition during the growth period. The positive effect of supplementation with multi-vitamins and minerals on bone growth and quality was followed by the formation of mineral deposits on the rats' kidneys and modifications in the expression of genes involved in inflammation and vitamin-D metabolism, demonstrating the cost of supplementation. Short and prolonged rescue improved trabecular parameters but incompletely improved the cortical parameters and the mechanical performance of the femur. Cortical porosity and cartilaginous lesions in the growth-plate were still detected one week after rescue and were reduced to normal levels 3 weeks after rescue. These findings highlight bone as a target for the effect of UPF and emphasize the importance of a balanced diet, especially during growth.

Conserved role of matrix metalloproteases 2 and 9 in promoting the migration of neural crest cells in avian and mammalian embryos.

Neural crest cells (NCCs) are a unique embryonic cell population that initially reside at the dorsal neural tube but later migrate in the embryo and differentiate into multiple types of derivatives. To acquire motility, NCCs undergo epithelial-to-mesenchymal transition and invade the surrounding extracellular matrix (ECM). Matrix metalloproteases (MMPs) are a large family of proteases which regulate migration of various embryonic and adult cells via ECM remodeling. The gelatinase's subgroup of MMPs is the most studied one due to its key role in metastasis. As it is composed of only two proteases, MMP2 and MMP9, it is important to understand whether each is indispensable or redundant in its biological function. Here we explored the role of the gelatinases in executing NCC migration, by determining whether MMP2 and/or MMP9 regulate migration across species in singular, combined, or redundant manners. Chick and mouse embryos were utilized to compare expression and activity of both MMPs using genetic and pharmacological approaches in multiple in vivo and ex vivo assays. Both MMPs were found to be expressed and active in mouse and chick NCCs. Inhibition of each MMP was sufficient to prevent NCC migration in both species. Yet, NCC migration was maintained in MMP2-/- or MMP9-/- mouse mutants due to compensation between the gelatinases, but reciprocal pharmacological inhibition in each mutant prevented NCC migration. This study reveals for the first time that both gelatinases are expressed in avian and mammalian NCCs, and demonstrates their fundamental and conserved role in promoting embryonic cell migration.

Association between abdominal obesity and fragility fractures among elderly Israeli women.

BACKGROUND: Obesity has been traditionally viewed as a protective factor for fractures. Recent studies have challenged this concept, particularly regarding abdominal obesity. We aimed to investigate the association between abdominal obesity, body mass index (BMI) and fragility fractures prevalence in a sample of community-dwelling elderly Israeli women. METHODS: The data in this cross-sectional study were based on 'Mabat Zahav'-a survey of a nationally representative sample of elderly Israelis. The study population included 669 women. Data on fragility fractures site and circumstances were self-reported, and height, weight, waist and calf circumferences were measured. Waist circumference (WC) variable was divided into tertiles: < 88 cm, 88-99 cm and > 99 cm. RESULTS: Sixty-five women reported fragility fractures (14 hip fractures, 18 vertebral fractures and 39 wrist fractures). Mean age was 73.9 ± 5.9 years, mean BMI was 29.9 ± 5 kg/m2 and mean WC was 93.9 ± 12 cm. While BMI was not associated with osteoporotic fractures, abdominal obesity (WC > 88 cm) was positively associated with fragility fractures, independently of age, smoking, physical activity [middle and high WC tertiles {3.15 (95% CI 1.41-7.02), 2.78 (95% CI 1.05-7.31), respectively}]. CONCLUSIONS: Among this sample of elderly women, abdominal obesity was positively associated with fragility fractures, independently of age, smoking, physical activity and BMI. Waist circumference, an easily measured anthropometric indicator, may be useful for assessing the risk of fragility fractures in elderly women, particularly among those with normal or high BMI-a vast population which has been traditionally considered as having lower fracture risk.

Mineral homeostasis and regulation of mineralization processes in the skeletons of sharks, rays and relatives (Elasmobranchii).

Sharks, rays and other elasmobranch fishes are characterized by a skeletal type that is unique among living vertebrates, comprised predominantly of an unmineralized cartilage, covered by a thin outer layer of sub-millimeter, mineralized tiles called tesserae. The mineralized portion of the skeleton appears to grow only by apposition, adding material at the edges of each tessera; maintenance of non-mineralized joints between tesserae is therefore vital, with precise control of mineral deposition and inhibition at the many thousands of growth fronts in the skeleton. Yet, we have only scattered evidence as to how the elasmobranchs mineralize and grow their skeletons. In this review, we take an "environment to skeleton" approach, drawing together research from a vast range of perspectives to track calcium and phosphate from the typical elasmobranch habitats into and through the body, to their deposition at tesseral growth fronts. In the process, we discuss the available evidence for skeletal resorption capability, mineral homeostasis hormones, and nucleation inhibition mechanisms. We also outline relevant theories in crystal nucleation and typical errors in measurements of serum calcium and phosphate in the study of vertebrate biology. We assemble research that suggests consensus in some concepts in elasmobranch skeletal development, but also highlight the very large gaps in our knowledge, particularly in regards to endocrine functional networks and biomineralization mechanisms. In this way, we lay out frameworks for future directions in the study of elasmobranch skeletal biology with stronger and more comparative links to research in other disciplines and into other taxa.

Validation of a Nutritional Screening Tool for Ambulatory Use in Pediatrics.

OBJECTIVES: To evaluate the use of Screening Tool for the Assessment of Malnutrition in Pediatrics (STAMP) in a primary health care clinic in the community and to assess the impact of its use on medical staff's awareness of nutritional status. METHODS: STAMP scoring system was tested as is and with modifications in the ambulatory setting. Nutritional risk according to STAMP was compared with a detailed nutritional assessment performed by a registered dietitian. Recording of nutrition-related data and anthropometric measurements in medical files were compared prior and post implementation. RESULTS: Sixty children were included (31 girls, 52%), ages between 1 and 6 years, mean age 2.8 ±â€Š1.5 (mean ±â€ŠSD). STAMP scores yielded a fair agreement between STAMP and the dietitian's nutritional assessment: κ = 0.47 (95% confidence interval [CI] 0.24-0.7), sensitivity of 47.62% (95% CI 28.34-67.63). Modified STAMP yielded more substantial agreement: κ = 0.57 (95% CI 0.35-0.79), sensitivity of 76.19% (95% CI 54.91-89.37), specificity of 82.05% (95% CI 67.33-91.02). The use of STAMP resulted in an increase in recording of appetite, dietary intake, and anthropometric measurements. CONCLUSIONS: Modification of the STAMP improved nutritional risk evaluation in community setting. The use of STAMP in a primary health care clinic raised clinician's awareness to nutritional status. Further work will identify whether this could be translated into lower malnutrition rates and better child care.

The growth plate's response to load is partially mediated by mechano-sensing via the chondrocytic primary cilium.

Mechanical load plays a significant role in bone and growth-plate development. Chondrocytes sense and respond to mechanical stimulation; however, the mechanisms by which those signals exert their effects are not fully understood. The primary cilium has been identified as a mechano-sensor in several cell types, including renal epithelial cells and endothelium, and accumulating evidence connects it to mechano-transduction in chondrocytes. In the growth plate, the primary cilium is involved in several regulatory pathways, such as the non-canonical Wnt and Indian Hedgehog. Moreover, it mediates cell shape, orientation, growth, and differentiation in the growth plate. In this work, we show that mechanical load enhances ciliogenesis in the growth plate. This leads to alterations in the expression and localization of key members of the Ihh-PTHrP loop resulting in decreased proliferation and an abnormal switch from proliferation to differentiation, together with abnormal chondrocyte morphology and organization. Moreover, we use the chondrogenic cell line ATDC5, a model for growth-plate chondrocytes, to understand the mechanisms mediating the participation of the primary cilium, and in particular KIF3A, in the cell's response to mechanical stimulation. We show that this key component of the cilium mediates gene expression in response to mechanical stimulation.

A discoidin domain receptor 1 knock-out mouse as a novel model for osteoarthritis of the temporomandibular joint.

Discoidin domain receptor 1 (DDR-1)-deficient mice exhibited a high incidence of osteoarthritis (OA) in the temporomandibular joint (TMJ) as early as 9 weeks of age. They showed typical histological signs of OA, including surface fissures, loss of proteoglycans, chondrocyte cluster formation, collagen type I upregulation, and atypical collagen fibril arrangements. Chondrocytes isolated from the TMJs of DDR-1-deficient mice maintained their osteoarthritic characteristics when placed in culture. They expressed high levels of runx-2 and collagen type I, as well as low levels of sox-9 and aggrecan. The expression of DDR-2, a key factor in OA, was increased. DDR-1-deficient chondrocytes from the TMJ were positively influenced towards chondrogenesis by a three-dimensional matrix combined with a runx-2 knockdown or stimulation with extracellular matrix components, such as nidogen-2. Therefore, the DDR-1 knock-out mouse can serve as a novel model for temporomandibular disorders, such as OA of the TMJ, and will help to develop new treatment options, particularly those involving tissue regeneration.

Effect of peripherally administered leptin antagonist on whole body metabolism and bone microarchitecture and biomechanical properties in the mouse.

Leptin's in vivo effect on the rodent skeleton depends on the model used and the mode of administration. Superactive mouse leptin antagonist (SMLA) was produced and then pegylated (PEG) to prolong and enhance its in vivo activity. We blocked leptin signaling by injecting this antagonist peripherally into normal mice at various time points and studied their metabolic and skeletal phenotypes. Subcutaneous PEG-SMLA injections into 4-wk-old female C57BL/6J mice increased weight gain and food consumption significantly after only 1 mo, and the effect lasted for the 3 mo of the experiment, proving its central inhibiting activity. Mice showed a significant increase in serum glucose, cholesterol, triglycerides, insulin, and HOMA-IR throughout the experiment. Quantification of gene expression in "metabolic" tissues also indicated the development of insulin resistance. Bone analyses revealed a significant increase in trabecular and cortical parameters measured in both the lumbar vertebrae and tibiae in PEG-SMLA-treated mice in the 1st and 3rd months as well as a significant increase in tibia biomechanical parameters. Interestingly, 30 days of treatment with the antagonist in older mice (aged 3 and 6 mo) affected body weight and eating behavior, just as they had in the 1-mo-old mice, but had no effect on bone parameters, suggesting that leptin's effect on bones, either directly or through its obesogenic effect, is dependent upon stage of skeletal development. This potent and reversible antagonist enabled us to study leptin's in vivo role in whole body and bone metabolism and holds potential for future therapeutic use in diseases involving leptin signaling.

Assessment of Relative Energy Deficiency in Sport (REDs) Risk among Adolescent Acrobatic Gymnasts.

Energy imbalance exposes athletes to relative energy deficiency in sports (REDs) syndrome. Data on energy consumption, REDs, and bone mineral density (BMD) in adolescent acrobatic gymnasts, especially in males, are scarce. Our aim was to examine the eating habits, energy balance, body composition, and BMD of these athletes. In this study, 18 healthy adolescents participating in competitive acrobatic gymnastics completed a questionnaire, underwent a dual-energy X-ray absorptiometry scan (DXA), received a food log, and had their activities monitored for 3 days. Eighteen acrobats were enrolled (mean age: 14.3 ± 1.2 years; males: 6/18). The mean total body BMD Z-score was 0.4 ± 1.0. Top-position acrobats (7/18) had significantly lower total body BMD Z-scores than base-positioned acrobats (-0.2 ± 0.3 vs. 0.8 ± 0.3, p = 0.032), though their forearms were not significantly different (0.2 ± 0.5 vs. 0.8 ± 0.7, p = 0.331). No sex differences were found for BMD Z-scores, BMI, or energy availability. The BMD parameters of the acrobats were within the normal range for a healthy pediatric population, although three had low BMDs (<-1 SD) for healthy athletes. Total body and LS BMD Z-scores were significantly lower in top-position athletes compared to base-position athletes. These findings suggest personalized (top vs. base) training programs (high-impact training) that may achieve better health outcomes.

Matrix metalloproteinase 9/gelatinase B is required for neural crest cell migration.

This study determined the role of MMP9/gelatinase B during the migration onset of Neural Crest Cells (NCC) in avian embryos. NCC are neuroepithelial progenitors that convert into mesenchyme and migrate along defined paths throughout the embryo. To engage in migration, NCC loose cell contacts, detach from the neural tube and invade the surrounding environment. Multiple signals and transcription factors that regulate these events have been identified. Nevertheless, little is known regarding effectors that act downstream to execute the actual NCC migration. Matrix metalloproteinases (MMPs) compose a large family of enzymes whose principal substrates are basement membranes, adhesion proteins and the extracellular matrix (ECM) components. A major subgroup of MMPs, the gelatinases (MMP9 and 2) are central to many adult physiological and pathological processes, such as tumor metastasis and angiogenesis, in which cell-cell and cell-matrix contacts are degraded to allow migration. As NCC undergo similar processes during development, we hypothesized that MMP9 may also promote the migration of NCC. MMP9 was found to be expressed in delaminating and migrating NCC of both cranial and trunk axial levels. Blocking MMP9 resulted in a dramatic inhibition of NCC delamination and migration, without perturbing specification or survival. This inhibition occurred at regions containing both premigratory and migrating cells, indicative for the central role of MMP9 in executing the detachment of NCC from the neural tube as well as their migration. Conversely, excess MMP9 enhanced mesenchymalization and delamination of NCC and accelerated progenitors to undergo precocious migration. Examination of the mechanistic activity of MMP9 revealed its capability to degrade the adhesion molecule N-cadherin as well as the basement-membrane protein laminin within or around NCC, respectively. Altogether, our study reveals MMP9 as a novel effector which is required for NCC delamination and migration.

IL-1RI participates in normal growth plate development and bone modeling.

The proinflammatory cytokine interleukin-1 (IL-1) signals through IL-1 receptor type I (IL-1RI) and induces osteoclastogenesis and bone resorption mainly during pathological conditions. Little is known about the effect of excess or absence of IL-1 signaling on the physiological development of the growth plate and bone. In this study, we examine growth plate morphology, bone structure, and mechanical properties as well as osteoclast number in IL-1RI knockout mice to evaluate the role of IL-1RI in the normal development of the growth plate and bone. We show for the first time that IL-1RI knockout mice have narrower growth plates due to a smaller hypertrophic zone, suggesting a role for this cytokine in hypertrophic differentiation, together with higher proteoglycan content. The bones of theses mice exhibit higher trabecular and cortical mass, increased mineral density, and superior mechanical properties. In addition, IL-1RI knockout mice have significantly reduced osteoclast numbers in the chondro-osseous junction, trabecular bone, and cortical bone. These results suggest that IL-1RI is involved in normal growth plate development and ECM homeostasis and that it is significant in the physiological process of bone modeling.

Differential gene expression in the calvarial and cortical bone of juvenile female mice.

Introduction: Both the calvarial and the cortical bones develop through intramembranous ossification, yet they have very different structures and functions. The calvaria enables the rapid while protected growth of the brain, whereas the cortical bone takes part in locomotion. Both types of bones undergo extensive modeling during embryonic and post-natal growth, while bone remodeling is the most dominant process in adults. Their shared formation mechanism and their highly distinct functions raise the fundamental question of how similar or diverse the molecular pathways that act in each bone type are. Methods: To answer this question, we aimed to compare the transcriptomes of calvaria and cortices from 21-day old mice by bulk RNA-Seq analysis. Results: The results revealed clear differences in expression levels of genes related to bone pathologies, craniosynostosis, mechanical loading and bone-relevant signaling pathways like WNT and IHH, emphasizing the functional differences between these bones. We further discussed the less expected candidate genes and gene sets in the context of bone. Finally, we compared differences between juvenile and mature bone, highlighting commonalities and dissimilarities of gene expression between calvaria and cortices during post-natal bone growth and adult bone remodeling. Discussion: Altogether, this study revealed significant differences between the transcriptome of calvaria and cortical bones in juvenile female mice, highlighting the most important pathway mediators for the development and function of two different bone types that originate both through intramembranous ossification.

The Impact of a Low-Carbohydrate Diet on Micronutrient Intake and Status in Adolescents with Type 1 Diabetes.

OBJECTIVE: The aim of this study was to evaluate the macronutrient and micronutrient intake and status in youth with type 1 diabetes mellitus (T1DM) following the consumption of a low-carbohydrate diet (LCD). RESEARCH METHODS AND PROCEDURES: In a prospective intervention clinical trial, adolescents with T1DM using a continuous glucose monitoring device were enrolled. Following a cooking workshop, each participant received a personalized diet regime based on LCD (50-80 g carbohydrate/day). A Food Frequency Questionnaire was administered, and laboratory tests were taken before and 6 months following the intervention. Twenty participants were enrolled. RESULTS: The median age was 17 years (15; 19), and the median diabetes duration was 10 years (8; 12). During the six-months intervention, carbohydrate intake decreased from 266 g (204; 316) to 87 g (68; 95) (p = 0.004). Energy intake, the energy percent from ultra-processed food, and fiber intake decreased (p = 0.001, p = 0.024, and p < 0.0001, respectively). These changes were accompanied by declines in BMI z-score (p = 0.019) and waist-circumference percentile (p = 0.007). Improvement was observed in the median HbA1c from 8.1% (7.5; 9.4) to 7.7% (6.9; 8.2) (p = 0.021). Significant declines below the DRI were shown in median intake levels of iron, calcium, vitamin B1, and folate. CONCLUSIONS: The LCD lowered ultra-processed food consumption, BMI z-scores and the indices of central obesity. However, LCDs require close nutritional monitoring due to the possibility of nutrient deficiencies.

The Mediterranean Diet for Adolescents with Type 1 Diabetes: A Prospective Interventional Study.

The Mediterranean diet (MED) is highly recommended. Medical nutrition therapy is the cornerstone of diabetes treatment. The primary outcome was to evaluate the change in micronutrient intake of youth with type 1 diabetes before and after a 6-month MED intervention; we also assessed adherence and glycemic control. Twenty adolescents, median age 18 years (interquartile range: 15.5-21), median diabetes duration 9 years (7-14), using continuous glucose monitoring devices, received personalized diet regimes based on MED. At 6 months post-intervention, the caloric intake remained unchanged; however, the carbohydrate proportion was lower (p = 0.058), and the intakes of some monounsaturated fats increased (p = 0.049). Sodium intake exceeded the recommended daily allowance by 250% (p = 0.653), before and after the intervention. For blood glucose, the percent TIR (time-in-range, 70-180 mg/dL) improved from 52% (38-60) to 63% (47-71) (p = 0.047). The total insulin dose decreased marginally, from 0.76 u/kg (0.64-0.97) to 0.72 u/kg (0.61-0.89) (p = 0.067). BMI z-score and waist circumference did not change (p = 0.316 and p = 0.161, respectively). Diastolic blood pressure percentile decreased from 73% (68-88) to 69% (50-79) (p = 0.028), and LDL cholesterol from 114 mg/dL (105-134) to 104 mg/dL (96-124) (p = 0.059). The Israeli Mediterranean diet screener score increased, from 8 (7-11) to 13 points (12-14) (p < 0.001). The MED-based intervention in youth with type 1 diabetes is feasible and leads to improvement in monounsaturated fat intake, TIR, and diastolic blood pressure. Other parameters show no change (caloric intake, BMI, and HbA1c).

Effect of milk fat globules on growth and metabolism in rats fed an unbalanced diet.

We assessed the effects of supplementing milk fat globules (MFG) on the growth and development of the skeleton in rats fed a Western unbalanced diet (UBD). The UBD is high in sugar and fat, low in protein, fiber, and micronutrients, and negatively impacts health. The MFG-a complex lipid-protein assembly secreted into milk-has a unique structure and composition, which differs significantly from isolated and processed dietary ingredients. Rats consuming the UBD exhibited growth retardation and disrupted bone structural and mechanical parameters; these were improved by supplementation with small MFG. The addition of small MFG increased the efficiency of protein utilization for growth, and improved trabecular and cortical bone parameters. Furthermore, consumption of UBD led to a decreased concentration of saturated fatty acids and increased levels of polyunsaturated fatty acids (PUFA), particularly omega-6 PUFA, in the serum, liver, and adipose tissue. The addition of small MFG restored PUFA concentration and the ratio of omega-6 to omega-3 PUFA in bone marrow and adipose tissue. Finally, large but not small MFG supplementation affected the cecal microbiome in rats. Overall, our results suggest that natural structure MFG supplementation can improve metabolism and bone development in rats fed an UBD, with the effects depending on MFG size. Moreover, the benefits of small MFG to bone development and metabolism were not mediated by the microbiome, as the detrimental effects of an UBD on the microbiome were not mitigated by MFG supplementation.

Comparison of structural, architectural and mechanical aspects of cellular and acellular bone in two teleost fish.

The histological diversity of the skeletal tissues of fishes is impressive compared with that of other vertebrate groups, yet our understanding of the functional consequences of this diversity is limited. In particular, although it has been known since the mid-1800s that a large number of fish species possess acellular bones, the mechanical advantages and consequences of this structural characteristic - and therefore the nature of the evolution of this feature - remain unclear. Although several studies have examined the material properties of fish bone, these have used a variety of techniques and there have been no direct contrasts of acellular and cellular bone. We report on a comparison of the structural and mechanical properties of the ribs and opercula between two freshwater fish - the common carp Cyprinus carpio (a fish with cellular bone) and the tilapia Oreochromis aureus (a fish with acellular bone). We used light microscopy to show that the bones in both fish species exhibit poor blood supply and possess discrete tissue zones, with visible layering suggesting differences in the underlying collagen architecture. We performed identical micromechanical testing protocols on samples of the two bone types to determine the mechanical properties of the bone material of opercula and ribs. Our data support the consensus of literature values, indicating that Young's moduli of cellular and acellular bones are in the same range, and lower than Young's moduli of the bones of mammals and birds. Despite these similarities in mechanical properties between the bone tissues of the fish species tested here, cellular bone had significantly lower mineral content than acellular bone; furthermore, the percentage ash content and bone mineral density values (derived from micro-CT scans) show that the bone of these fishes is less mineralized than amniote bone. Although we cannot generalize from our data to the numerous remaining teleost species, the results presented here suggest that while cellular and acellular fish bone may perform similarly from a mechanical standpoint, there are previously unappreciated differences in the structure and composition of these bone types.

Bone Gla protein increases HIF-1alpha-dependent glucose metabolism and induces cartilage and vascular calcification.

OBJECTIVE: Bone Gla Protein (BGP, osteocalcin) is commonly present in the calcified vasculature and was recently shown as energy metabolism-regulating hormone. This study investigates the role of BGP in cartilage and vasculature mineralization. METHODS AND RESULTS: We established an in vitro BGP-overexpression model in chondrocytes (ATDC5) and vascular smooth muscle cells (MOVAS). BGP overexpression upregulated markers of chondrogenic differentiation and intensified staining for minerals. BGP overexpression enhanced glucose uptake and increased expression of glucose transporters and glycolysis enzymes while decreasing gluconeogenesis enzymes. Treatment with purified BGP activated insulin signaling pathway and upregulated genes of glucose transport and utilization. Both BGP overexpression and treatment with purified BGP resulted in stabilization of hypoxia-inducible factor 1α (HIF-1α) in chondrocytes and vascular smooth muscle cells, shown essential in mediating the direct metabolic effect of BGP. The in vivo model of 1,25(OH)(2)D(3)-induced vascular calcification in rats revealed a correlation between calcification, elevated BGP levels, and increased HIF-1α expression in aortas and bone growth plates. The in vivo introduction of BGP siRNA, coadministered with 1,25(OH)(2)D(3), prevented 1,25(OH)(2)D(3)-induced HIF-1α stabilization, and diminished osteochondrogenic differentiation and mineralization of aortas. CONCLUSIONS: This study demonstrates novel mechanism by which BGP locally shifts cells toward glycolytic breakdown of glucose, in a HIF-1α-dependent manner, and stimulates calcification of cartilage and vasculature.

Revisiting Protein Quality Assessment to Include Alternative Proteins.

The high demand for novel and existing sustainable protein sources (e.g., legumes, insects, algae, and cultured meat) to replace the animal-based sources is becoming crucial. This change in protein consumption calls for the re-evaluation of the current methods to assess their quality and bioavailability. The two conventional scores for PDCAAS (protein digestibility-corrected AA score) and DIAAS (Digestible Indispensable AA Score) have their limitations and have not been re-evaluated and updated to address plant and novel proteins' quality. We suggest a sensitive physiological preclinical model that can rapidly and confidently address proteins from different sources. Our model is based on the postnatal growth, a major parameter for development and health in children, that influenced by environmental nutritional and lifestyle factors. Our results demonstrate that, with an appropriate amount of protein in the diet, almost all tested proteins performed as well as casein, the animal source. However, upon restriction (10% of calories), all alternative sources did not accomplish normal growth performance. Surprisingly, when compared to PDCAAS and DIAAS parameters obtained from the literature, no correlations were found between growth performance and these parameters, demonstrating their limitations.