Modeling Early Stage Bone Regeneration With Biomimetic Electrospun Fibrinogen Nanofibers and Adipose-Derived Mesenchymal Stem Cells

The key events of the earliest stages of bone regeneration have been described in vivo although not yet modeled in an in vitro environment, where mechanistic cell-matrix-growth factor interactions can be more effectively studied. Here, we explore an early-stage bone regeneration model where the ability of electrospun fibrinogen (Fg) nanofibers to regulate osteoblastogenesis between distinct mesenchymal stem cells populations is assessed. Electrospun scaffolds of Fg, polydioxanone (PDO), and a Fg:PDO blend were seeded with adipose-derived mesenchymal stem cells (ASCs) and grown for 7-21 days in osteogenic differentiation media or control growth media. Scaffolds were analyzed weekly for histologic and molecular evidence of osteoblastogenesis. In response to osteogenic differentiation media, ASCs seeded on the Fg scaffolds exhibit elevated expression of multiple genes associated with osteoblastogenesis. Histologic stains and scanning electron microscopy demonstrate widespread mineralization within the scaffolds, as well as de novo type I collagen synthesis. Our data demonstrates that electrospun Fg nanofibers support ASC osteogenic differentiation, yet the scaffold itself does not appear to be osteoinductive. Together, ASCs and Fg recapitulate early stages of bone regeneration ex vivo and presents a prospective autologous therapeutic approach for bone repair

Oxygen Glucose Deprivation in Rat Hippocampal Slice Cultures Results in Alterations in Carnitine Homeostasis and Mitochondrial Dysfunction

Mitochondrial dysfunction characterized by depolarization of mitochondrial membranes and the initiation of mitochondrial-mediated apoptosis are pathological responses to hypoxia-ischemia (HI) in the neonatal brain. Carnitine metabolism directly supports mitochondrial metabolism by shuttling long chain fatty acids across the inner mitochondrial membrane for beta-oxidation. Our previous studies have shown that HI disrupts carnitine homeostasis in neonatal rats and that L-carnitine can be neuroprotective. Thus, this study was undertaken to elucidate the molecular mechanisms by which HI alters carnitine metabolism and to begin to elucidate the mechanism underlying the neuroprotective effect of L-carnitine (LCAR) supplementation. Utilizing neonatal rat hippocampal slice cultures we found that oxygen glucose deprivation (OGD) decreased the levels of free carnitines (FC) and increased the acylcarnitine (AC): FC ratio. These changes in carnitine homeostasis correlated with decreases in the protein levels of carnitine palmitoyl transferase (CPT) 1 and 2. LCAR supplementation prevented the decrease in CPT1 and CPT2, enhanced both FC and the AC: FC ratio and increased slice culture metabolic viability, the mitochondrial membrane potential prior to OGD and prevented the subsequent loss of neurons during later stages of reperfusion through a reduction in apoptotic cell death. Finally, we found that LCAR supplementation preserved the structural integrity and synaptic transmission within the hippocampus after OGD. Thus, we conclude that LCAR supplementation preserves the key enzymes responsible for maintaining carnitine homeostasis and preserves both cell viability and synaptic transmission after OGD

Neutral Effect of Exenatide on Serum Testosterone in Men with Type 2 Diabetes Mellitus: A Prospective Cohort

BACKGROUND: Endogenous testosterone increases with weight loss from diet, exercise, and bariatric surgery. However, little is known about testosterone levels after weight loss from medication. OBJECTIVES: Uncover the effects of Glucagon-Like Peptide-1 receptor agonist (GLP-1 RA) therapy on serum testosterone. MATERIAL AND METHODS: Prospective cohort study of men starting GLP-1 RA therapy for type 2 diabetes mellitus. RESULTS: 51 men lost 2.27 kg (p = 0.00162) and their HbA1c values improved by 0.7% (p = 0.000503) after 6 months of GLP-1 RA therapy. There was no significant change in testosterone for the group as a whole. However, in subgroup analyses, there was a significant difference in total testosterone change between men starting with baseline total testosterone/dL (238.5 ± 56.5 ng/dL to 272.2 ± 82.3 ng/dL) compared to higher values (438 ± 98.2 ng/dL to 412 ± 141.2 ng/dL) (p = 0.0172);free testosterone increased if the baseline total testosterone was/dL (55.2 ± 12.8 pg/mL to 57.2 ± 17.6 pg/mL) and decreased if \u3e320 ng/dL (74.7 ± 16.3 pg/mL to 64.2 ± 17.7 pg/mL) (p = 0.00807). Additionally, there were significant differences in testosterone change between men with HbA1c improvements ≥1% (351.6 ± 123.9 ng/dL to 394.4 ± 136.5 ng/dL) compared to men with HbA1c changes CONCLUSION: GLP-1 RA therapy improves weight and HbA1c without adverse effects on testosterone. Those starting with lower testosterone values or attaining greater improvement in HbA1c may see additional benefits

Regulation of ␣4␤2 Nicotinic Receptor Desensitization by Calcium and Protein Kinase C

ABSTRACT Neuronal nicotinic acetylcholine receptor (nAChR) desensitization is hypothesized to be a trigger for long-term changes in receptor number and function observed after chronic administration of nicotine at levels similar to those found in persons who use tobacco. Factors that regulate desensitization could potentially influence the outcome of long-lasting exposure to nicotine. The roles of Ca 2ϩ and protein kinase C (PKC) on desensitization of ␣4␤2 nAChRs expressed in Xenopus laevis oocytes were investigated. Nicotine-induced (300 nM; 30 min) desensitization of ␣4␤2 receptors in the presence of Ca 2ϩ developed in a biphasic manner with fast and slow exponential time constants of f ϭ 1.4 min (65% relative amplitude) and s ϭ 17 min, respectively. Recovery from desensitization was reasonably well described by a single exponential with rec ϭ 43 min. Recovery was largely eliminated after replacement of external Ca 2ϩ with Ba 2ϩ and slowed by calphostin C ( rec ϭ 48 min), an inhibitor of PKC. Conversely, the rate of recovery was enhanced by phorbol-12-myristate-13-acetate ( rec ϭ 14 min), a PKC activator, or by cyclosporin A (with rec ϭ 8 min), a phosphatase inhibitor. ␣4␤2 receptors containing a mutant ␣4 subunit that lacks a consensus PKC phosphorylation site exhibited little recovery from desensitization. Based on a twodesensitized-state cyclical model, it is proposed that after prolonged nicotine treatment, ␣4␤2 nAChRs accumulate in a "deep" desensitized state, from which recovery is very slow. We suggest that PKC-dependent phosphorylation of ␣4 subunits changes the rates governing the transitions from "deep" to "shallow" desensitized conformations and effectively increases the overall rate of recovery from desensitization. Longlasting dephosphorylation may underlie the "permanent" inactivation of ␣4␤2 receptors observed after chronic nicotine treatment

Wild-type and mutant SOD1 share an aberrant conformation and a common pathogenic pathway in ALS.

Many mutations confer one or more toxic function(s) on copper/zinc superoxide dismutase 1 (SOD1) that impair motor neuron viability and cause familial amyotrophic lateral sclerosis (FALS). Using a conformation-specific antibody that detects misfolded SOD1 (C4F6), we found that oxidized wild-type SOD1 and mutant SOD1 share a conformational epitope that is not present in normal wild-type SOD1. In a subset of human sporadic ALS (SALS) cases, motor neurons in the lumbosacral spinal cord were markedly C4F6 immunoreactive, indicating that an aberrant wild-type SOD1 species was present. Recombinant, oxidized wild-type SOD1 and wild-type SOD1 immunopurified from SALS tissues inhibited kinesin-based fast axonal transport in a manner similar to that of FALS-linked mutant SOD1. Our findings suggest that wild-type SOD1 can be pathogenic in SALS and identify an SOD1-dependent pathogenic mechanism common to FALS and SALS

Examining the generalizability of research findings from archival data

This initiative examined systematically the extent to which a large set of archival research findings generalizes across contexts. We repeated the key analyses for 29 original strategic management effects in the same context (direct reproduction) as well as in 52 novel time periods and geographies; 45% of the reproductions returned results matching the original reports together with 55% of tests in different spans of years and 40% of tests in novel geographies. Some original findings were associated with multiple new tests. Reproducibility was the best predictor of generalizability—for the findings that proved directly reproducible, 84% emerged in other available time periods and 57% emerged in other geographies. Overall, only limited empirical evidence emerged for context sensitivity. In a forecasting survey, independent scientists were able to anticipate which effects would find support in tests in new samples

Mechanical properties and cellular proliferation of electrospun collagen type II

A suitable technique for articular cartilage repair and replacement is necessitated by inadequacies of current methods. Electrospinning has potential in cartilage repair by producing scaffolds with fiber diameters in the range of native extracellular matrix. Chondrocytes seeded onto such scaffolds may prefer this environment for differentiation and proliferation, thus approaching functional cartilage replacement tissue. Scaffolds of collagen type II were created by an electrospinning technique. Individual scaffold specimens were prepared and evaluated as uncross-linked, cross-linked, or cross-linked/seeded. Uncross-linked scaffolds contained a minimum and average fiber diameter of 70 and 496 nm, respectively, whereas cross-linked scaffolds possessed diameters of 140 nm and 1.46 μm. The average thickness for uncross-linked scaffolds was 0.20 ± 0.02 mm and 0.52 ± 0.07 mm for cross-linked scaffolds. Uniaxial tensile tests of uncross-linked scaffolds revealed an average tangent modulus, ultimate tensile strength, and ultimate strain of 172.5 ± 36.1 MPa, 3.3 ± 0.3 MPa, and 0.026 ± 0.005 mm/mm, respectively. Scanning electron microscopy of cross-linked scaffolds cultured with chondrocytes demonstrated the ability of the cells to infiltrate the scaffold surface and interior. Electrospun collagen type II scaffolds produce a suitable environment for chondrocyte growth, which potentially establishes the foundation for the development of articular cartilage repair

Snoring and carotid artery disease: A new risk factor emerges

OBJECTIVES/HYPOTHESIS: Previous studies have identified a relationship between snoring, carotid intima media thickening, and the presence of atherosclerosis. This study examines the correlation between snoring and carotid artery disease through use of duplex ultrasound identifying greater than 50% internal carotid artery stenosis. STUDY DESIGN: Prospective cohort study. METHODS: Patients presenting to three academic vascular laboratories for carotid duplex examination completed the following surveys: demographic information, assessment of risk factors for carotid stenosis, assessment of history of obstructive sleep apnea, or continuous positive airway pressure use and Snoring Outcomes Survey. Patients were categorized into 2 groups based on the presence or absence of carotid disease. Data were analyzed by univariate contingency tables and logistic regression analysis. RESULTS: Five hundred one patients completed the survey, of whom 243/501 (49%) had evidence of carotid occlusive disease. On univariate analysis, smoking, hypertension, heart disease, hypercholesterolemia, diabetes, and stroke all correlated with greater than 50% carotid stenosis. Multivariate analysis indicated that snorers were significantly more likely to have carotid disease. Three hundred twenty-seven participants were thought to have primary snoring. On univariate analysis, snorers were found to be significantly more likely to have carotid disease. After adjustment for covariates, snoring was not significant for carotid disease. However, multivariate analysis showed snorers to be significantly more likely to have bilateral carotid disease. CONCLUSIONS: This study shows a potential relationship between snoring and bilateral carotid artery stenosis greater than 50%; snorers have risk of carotid stenosis twice that of nonsnorers. Further investigation is warranted to better elucidate this relationship. LEVEL OF EVIDENCE: 2b Laryngoscope, 129:265-268, 2019