The Impact of Reduced Skeletal Muscle Mass on Patients with Knee Osteoarthritis

Although several studies have suggested a possible association between sarcopenia and knee osteoarthritis (OA) in the elderly, there remains no definitive evidence. Recently, however, the serum creatinine/cystatin C ratio (sarcopenia index: SI) was reported to correlate with skeletal muscle mass. The present retrospective study therefore investigated the impact of reduced skeletal muscle mass on advanced knee OA using SI. In 55 individuals scheduled for knee osteotomy or knee arthroplasty, correlations between SI and patient-reported outcomes such as the Knee Society Score (KSS), Knee Injury and Osteoarthritis Outcome Score (KOOS), and Oxford Knee Score (OKS) were explored. Significant associations were found between SI and the KSS functional activity score (β=0.37; p=0.022), KOOS subscale for activities of daily living (β=0.42; p=0.0096), and OKS (β=0.42; p=0.0095). This study underscores the role of reduced muscle mass in functional outcomes and introduces SI as a valuable marker for assessing muscle loss in knee OA patients

Imaging analysis reveals mechanistic differences between first- and second-phase insulin exocytosis

The mechanism of glucose-induced biphasic insulin release is unknown. We used total internal reflection fluorescence (TIRF) imaging analysis to reveal the process of first- and second-phase insulin exocytosis in pancreatic β cells. This analysis showed that previously docked insulin granules fused at the site of syntaxin (Synt)1A clusters during the first phase; however, the newcomers fused during the second phase external to the Synt1A clusters. To reveal the function of Synt1A in phasic insulin exocytosis, we generated Synt1A-knockout (Synt1A−/−) mice. Synt1A−/− β cells showed fewer previously docked granules with no fusion during the first phase; second-phase fusion from newcomers was preserved. Rescue experiments restoring Synt1A expression demonstrated restoration of granule docking status and fusion events. Inhibition of other syntaxins, Synt3 and Synt4, did not affect second-phase insulin exocytosis. We conclude that the first phase is Synt1A dependent but the second phase is not. This indicates that the two phases of insulin exocytosis differ spatially and mechanistically

Data supporting ER stress response in NG108-15 cells involves upregulation of syntaxin 5 expression and reduced amyloid β peptide secretion

This data contains insights into the upregulation of the ER-Golgi-soluble N-ethylmaleimide-sensitive factor-attachment protein receptors (ER–Golgi SNAREs) syntaxin 5 (Syx5) by ER stress and the downregulation of Syx5 by apoptosis induction. Use of the protein synthesis inhibitor verified the de novo synthesis of Syx5 under ER stress in NG108-15 cells. We also provide validation data for the increase of Syx5 expression caused by ER stress using different chemical compound and overexpression analysis. Interpretation of our data and further extensive insights into the role of Syx5 in βAPP processing under ER stress can be found in Suga et al. (2015) [1]