Connexin hemichannels drive lactation-induced osteocyte acidification and perilacunar-canalicular remodeling.

The maternal skeleton experiences significant bone loss during lactation, followed by rapid restoration post weaning. Parathyroid-related protein (PTHrP)-induced acidification of the perilacunar matrix by osteocytes is crucial in this process, yet its mechanism remains unclear. Here, we identify Cx43 hemichannels (HCs) as key mediators of osteocyte acidification and perilacunar-canalicular remodeling (PLR).

Overexpression of ameloblastin in secretory ameloblasts results in demarcated, hypomineralized opacities in enamel.

Developmental defects of the enamel manifest before tooth eruption and include amelogenesis imperfecta, a rare disease of underlying gene mutations, and molar-incisor hypomineralization (MIH), a prevalent disease in children originating from environmental and epigenetic factors. MIH enamel presents as the abnormal enamel marked by loss of translucency, demarcation between the healthy and affected enamel, and reduced mineral content. The pathophysiology of opaque, demarcated enamel lesions is not understood; however, the retention of enamel proteins in the matrix has been suggested.

Promotion of Joint Degeneration and Chondrocyte Metabolic Dysfunction by Excessive Growth Hormone in Mice.

Objective: Many patients with acromegaly, a hormonal disorder with excessive growth hormone (GH) production, report pain in joints. We undertook this study to characterize the joint pathology of mice with overexpression of bovine GH (bGH) or a GH receptor antagonist (GHa) and to investigate the effect of GH on regulation of chondrocyte cellular metabolism.

Methods: Knee joints from mice overexpressing bGH or GHa and wild-type (WT) control mice were examined using histology and micro-computed tomography for osteoarthritic (OA) pathologies.

A New Method of Bone Stromal Cell Characterization by Flow Cytometry.

The bone microenvironment cellular composition plays an essential role in bone health and is disrupted in bone pathologies, such as osteoporosis, osteoarthritis, and cancer. Flow cytometry protocols for hematopoietic stem cell lineages are well defined and well established. Additionally, a consensus for mesenchymal stem cell flow markers has been developed.

CSF-1 in Osteocytes Inhibits Nox4-mediated Oxidative Stress and Promotes Normal Bone Homeostasis.

CSF-1 is a key factor in regulating bone remodeling; osteocytes express CSF-1 and its receptor. Viable osteocytes are essential for bone remodeling through cell-cell contact and secretion of factors that regulate osteoblasts and osteoclasts. Increased oxidative stress contributes to osteocyte death and correlates with bone loss during aging.

Healthcare disparities in adolescent idiopathic scoliosis: the impact of socioeconomic factors on Cobb angle.

Study Design: Retrospective chart review.

Objectives: The aim of this study is to assess the role of insurance type, geographic socioeconomic status, and ethnicity in AIS disease severity in a state with mandated scoliosis screenings. Early detection of adolescent idiopathic scoliosis (AIS) is associated with reduced curve progression, surgical treatment, and long-term sequelae.

Connexin 43 hemichannels protect bone loss during estrogen deficiency.

Estrogen deficiency in postmenopausal women is a major cause of bone loss, resulting in osteopenia, osteoporosis, and a high risk for bone fracture. Connexin 43 (Cx43) hemichannels (HCs) in osteocytes play an important role in osteocyte viability, bone formation, and remodeling. We showed here that estrogen deficiency reduced Cx43 expression and HC function.

Validity of the Hispanic version of the American Academy of Orthopaedic Surgeons Foot and Ankle Outcomes Questionnaire in patients with traumatic foot and ankle injuries.

Background: Hispanics represent the largest minority group in the United States and are projected to represent 29% of the US population by 2060. Enrolling Hispanic patients in clinical outcome trials is critical to study a representative sample of the general population. Lack of translated and validated survey tools has been identified as a major barrier to enrolling Spanish speaking patients.

Ethnic differences in patients' perceptions towards isolated orthopedic injuries: a pilot study.

Background: Patients' perceptions of their healthcare have been reported to influence clinical outcomes following orthopedic trauma. Findings across clinical outcomes have demonstrated significant differences in perceptions towards healthcare between Hispanics and non-Hispanic whites. However, ethnic disparities in perceptions towards orthopedic injuries have not been examined in the literature.

Publication Productivity of Orthopaedic Surgery Chairs.

Background: As academic leaders, orthopaedic chairs represent role models for scholarly activities. Despite the importance of journal publications as a measure of scholarly activity, data on the publication productivity of orthopaedic chairs remain limited. The goals of this study were to record the publication productivity of orthopaedic chairs and evaluate the extent to which they maintained their scholarly activity while serving as chairs.

Spanish Translation, Cross-Cultural Adaptation, and Validation of the American Academy of Orthopaedic Surgeons Foot and Ankle Outcomes Questionnaire in Mexican-Americans With Traumatic Foot and Ankle Injuries.

Background: Hispanics represent the largest minority group within the US population accounting for an estimated 55.4 million individuals. Enrolling Hispanics into clinical outcome studies is important in order for study populations to be externally valid and representative of the US population.

Is Diabetic Skeletal Fragility Associated with Microvascular Complications in Bone?

Purpose Of Review: The objective of this literature review is to determine whether there are indications that microvascular complications occur in diabetic bone. Evidence definitively linking diabetic skeletal fragility with microvascular complications in bone remains elusive.

Recent Findings: Circumstantial evidence, some recent and some lost to time, suggests that atherosclerotic vascular diseases such as peripheral arterial disease cause poor blood perfusion of bone and subsequent hypoxia and contribute to low bone density and high cortical porosity, patterns similar to some recently observed in diabetic subjects.

Capsaicin-sensitive Innervation Modulates the Development of Apical Periodontitis.

Introduction: Nociceptive neurons play a critical role in the detection of stimuli evoking actual or potential tissue injury. In addition, they are involved in neurogenic inflammation by the peripheral release of neuropeptides such as calcitonin gene-related peptide (CGRP). The dental pulp and periradicular tissues are innervated by capsaicin-sensitive neurons known to release CGRP.

Maturation stage enamel malformations in Amtn and Klk4 null mice.

Amelotin (AMTN) and kallikrein-4 (KLK4) are secreted proteins specialized for enamel biomineralization. We characterized enamel from wild-type, Amtn(-/-), Klk4(-/-), Amtn(+/-)Klk4(+/-) and Amtn(-/-)Klk4(-/-) mice to gain insights into AMTN and KLK4 functions during amelogenesis. All of the null mice were healthy and fertile.

Estrogen and estrogen receptor alpha promotes malignancy and osteoblastic tumorigenesis in prostate cancer.

The role of estrogen signaling in regulating prostate tumorigenesis is relatively underexplored. Although, an increasing body of evidence has linked estrogen receptor beta (ERß) to prostate cancer, the function of estrogen receptor alpha (ERα) in prostate cancer is not very well studied. We have discovered a novel role of ERα in the pathogenesis of prostate tumors.

Connexin 43 channels are essential for normal bone structure and osteocyte viability.

Connexin (Cx) 43 serves important roles in bone function and development. Targeted deletion of Cx43 in osteoblasts or osteocytes leads to increased osteocyte apoptosis, osteoclast recruitment, and reduced biomechanical properties. Cx43 forms both gap junction channels and hemichannels, which mediate the communication between adjacent cells or between cell and extracellular environments, respectively.

Correlation of ameloblastin with enamel mineral content.

In enamel formation, the deposition of minerals as crystallites starts when the mineralization front first forms at the start of the secretory stage. During maturation, the enamel layer accumulates significant amounts of new mineral as the crystallites grow in volume. Inversely related to mineral gain is loss of protein and water from the forming enamel.

Caspase-2 maintains bone homeostasis by inducing apoptosis of oxidatively-damaged osteoclasts.

Osteoporosis is a silent disease, characterized by a porous bone micro-structure that enhances risk for fractures and associated disabilities. Senile, or age-related osteoporosis (SO), affects both men and women, resulting in increased morbidity and mortality. However, cellular and molecular mechanisms underlying senile osteoporosis are not fully known.

A review of rodent models of type 2 diabetic skeletal fragility.

Evidence indicating that adult type 2 diabetes (T2D) is associated with increased fracture risk continues to mount. Unlike osteoporosis, diabetic fractures are associated with obesity and normal to high bone mineral density, two factors that are typically associated with reduced fracture risk. Animal models will likely play a critical role in efforts to identify the underlying mechanisms of skeletal fragility in T2D and to develop preventative treatments.

Conditional deletion of cytochrome p450 reductase in osteoprogenitor cells affects long bone and skull development in mice recapitulating antley-bixler syndrome: role of a redox enzyme in development.

NADPH-cytochrome P450 oxidoreductase (POR) is the primary electron donor for cytochromes P450, dehydrocholesterol reductase, heme oxygenase, and squalene monooxygenase. Human patients with specific mutations in POR exhibit severe developmental malformations including disordered steroidogenesis, sexual ambiguities and various bone defects, similar to those seen in patients with Antley-Bixler syndrome (ABS). To probe the role of POR during bone development, we generated a conditional knockout mouse (CKO) by cross breeding Por (lox/lox) and Dermo1 Cre mice.

Analysis of neurovascular safety between superior and anterior plating techniques of clavicle fractures.

Objectives: Clavicle fractures are commonly plated as a method of fixation, with superior and anterior techniques described. Although advantages and disadvantages have been attributed to both, it is unclear if one approach provides a lower risk of neurovascular injury. The aim of this study was to compare the potential for neurovascular injury between these 2 plate locations in a cadaveric model.

Lumbar vertebral body bone microstructural scaling in small to medium-sized strepsirhines.

Bone mass, architecture, and tissue mineral density contribute to bone strength. As body mass (BM) increases any one or combination of these properties could change to maintain structural integrity. To better understand the structural origins of vertebral fragility and gain insight into the mechanisms that govern bone adaptation, we conducted an integrative analysis of bone mass and microarchitecture in the last lumbar vertebral body from nine strepsirhine species, ranging in size from 42 g (Microcebus rufus) to 2,440 g (Eulemur macaco).

Hyperglycemia and xerostomia are key determinants of tooth decay in type 1 diabetic mice.

Insulin-dependent type 1 diabetes mellitus (DM) and oral diseases are closely interrelated. Poor metabolic control in diabetics is associated with a high risk of gingivitis, periodontitis and tooth loss. Salivary flow declines in diabetics and patients suffer from xerostomia.

Further improvements on the factors affecting bone mineral density measured by quantitative micro-computed tomography.

The effects of imaging parameters and special configuration of objects within the reconstruction space on the micro computed tomography (μCT) based mineral density have been explored, and a series of density correction curves have been presented. A manufacturer-provided calibration phantom (0, 100, 200, 400, 800 mg HA/cm(3)) was imaged at all possible imaging conditions (n=216) based on energy, resolution, vial diameter, beam hardening correction factor and averaging. For each imaging condition, a linear regression model was fitted to the observed versus expected densities, and the intercepts (β(0)) and slopes (β(1)) of the regression lines and each density level were modeled using multiple regression modeling.

Meox2Cre-mediated disruption of CSF-1 leads to osteopetrosis and osteocyte defects.

CSF-1, a key regulator of mononuclear phagocyte production, is highly expressed in the skeleton by osteoblasts/osteocytes and in a number of nonskeletal tissues such as uterus, kidney and brain. The spontaneous mutant op/op mouse has been the conventional model of CSF-1 deficiency and exhibits a pleiotropic phenotype characterized by osteopetrosis, and defects in hematopoiesis, fertility and neural function. Studies to further delineate the biologic effect of CSF-1 within various tissues have been hampered by the lack of suitable models.