Vitronectin regulates osteoclastogenesis and bone remodeling in a mouse model of osteoporosis.

Vitronectin (VN) is an extracellular matrix protein with a crucial role in regulating bone remodeling. In this study, we aimed to investigate the effect of VN deficiency in a mouse model of osteoporosis induced by ovariectomy (OVX). The findings revealed that the absence of VN led to an increase in the activity of tartrate-resistant acid phosphatase (TRAP), a marker for osteoclasts, in the plasma of OVX-operated mice. TRAP staining further demonstrated that VN deficiency resulted in a higher number of osteoclasts within the femurs of OVX-operated mice. X-ray micro-computed tomography analysis of the femurs in OVX-operated mice indicated that VN deficiency significantly suppressed the OVX-induced increase of marrow area and total volume of bone. Additionally, we assessed structural model index (SMI) and degree of anisotropy (DA) as indices of osteoporosis. The results showed that VN deficiency effectively attenuated the OVX-induced increase in SMI and DA among OVX-operated mice. In summary, our study demonstrates the vital role of VN in regulating osteoclastogenesis and bone remodeling in the mouse model of osteoporosis.

[A case of giant cell arteritis after prednisolone dose reduction during treatment of polymyalgia rheumatica].

Giant cell arteritis (GCA) is closely associated with polymyalgia rheumatica (PMR). We herein report an 82-year-old woman who developed GCA during PMR treatment. She initially presented with shoulder pain and was diagnosed with PMR based on elevated serum C-reactive protein (CRP) levels and bursitis detected in both shoulders on ultrasonography (US). Treatment was initiated with a daily dose of 15 mg prednisolone (PSL), which led to rapid symptom alleviation, and the dosage was tapered to 1 mg/day. One month later, she developed myalgia extending from the lumbar region to the thigh and tenderness in the left temporal region. However, no abnormalities in the temporal artery were observed on US. Although the PSL dose was increased to 2 mg for relapse of PMR, the symptoms did not improve. One week later, she developed occipital pain with an increased CRP level of 9 mg/dL. She was diagnosed with GCA based on the 1990 ACR Classification Criteria. Fluorodeoxyglucose-positron emission tomography/computed tomography (FDG-PET/CT) detected anomalous accumulations in the bilateral superficial temporal and vertebral arteries, but not in the larger vessels. We therefore diagnosed her with cranial-type GCA. At this time point, we repeated US and found a halo sign in the temporal artery. Although epithelioid and giant cells were not observed in the temporal artery biopsy, vascular inflammatory findings such as disruption of the internal elastic lamina and chronic inflammatory cell infiltration were noted. Symptoms improved immediately and CRP levels decreased after the PSL dose was increased to 30 mg daily. To mitigate the risk of steroid-induced diabetes, tocilizumab was introduced, and gradual tapering of PSL was implemented. In conclusion, we encountered a case of GCA that developed after PSL reduction during the course of PMR. PET/CT confirmed intracranial artery inflammation and facilitated a definitive diagnosis. Although PET/CT cannot be routinely performed for diagnose in Japan, we consider it useful as an adjunctive diagnostic tool.

Kinetic modeling and sensitivity analysis of acetone-butanol-ethanol production.

A kinetic simulation model of metabolic pathways that describes the dynamic behaviors of metabolites in acetone-butanol-ethanol (ABE) production by Clostridium saccharoperbutylacetonicum N1-4 was proposed using a novel simulator WinBEST-KIT. This model was validated by comparing with experimental time-course data of metabolites in batch cultures over a wide range of initial glucose concentrations (36.1-295 mM). By introducing substrate inhibition, product inhibition of butanol, activation of butyrate and considering the cessation of metabolic reactions in the case of insufficiency of energy after glucose exhaustion, the revised model showed 0.901 of squared correlation coefficient (r(2)) between experimental time-course of metabolites and calculated ones. Thus, the final revised model is assumed to be one of the best candidates for kinetic simulation describing dynamic behavior of metabolites in ABE production. Sensitivity analysis revealed that 5% increase in reaction of reverse pathway of butyrate production (R(17)) and 5% decrease in reaction of CoA transferase for butyrate (R(15)) highly contribute to high production of butanol. These system analyses should be effective in the elucidation which pathway is metabolic bottleneck for high production of butanol.