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The global incidence of diabetes mellitus (DM) is increasing. Types 1 and 2 DM are associated with declining β-cell function. Verapamil (50% S-verapamil and 50% R-verapamil) can treat DM by downregulating thioredoxin-interacting protein (TXNIP), which induces islet β-cell apoptosis. However, it may also induce cardiovascular side effects as S-verapamil is negatively inotropic. In contrast, R-verapamil only weakly induces adverse cardiac effects. In this study, we aimed to determine the antidiabetic efficacy and cardiovascular safety of R-verapamil. We examined R- and S-verapamil binding through in vitro studies. Streptozotocin-induced type 1 and db/db type 2 DM mouse models were used to assess the antidiabetic efficacy of verapamil. IL-6, blood glucose (BG), Txnip expression, and β-cells were evaluated in streptozotocin-induced diabetic mice, while body weight, BG, and serum insulin were measured in the db/db mice. In the type 1 DM study, 100 mg/kg/day R-verapamil and racemic verapamil lowered BG, downregulated Txnip expression, and reduced β-cell apoptosis. In the type 2 DM study, the optimal R-verapamil dosage was 60 mg/kg/day and it lowered BG and raised serum insulin. However, efficacy did not increase with R-verapamil dosage. R-verapamil combined with metformin/acarbose improved BG and serum insulin more effectively than metformin/acarbose alone or verapamil combined with acarbose. R-verapamil had weaker cardiovascular side effects than S-verapamil. R-verapamil was 9.0× and 3.4× less effective than S-verapamil at inhibiting atrial inotropy and ileal contractility, respectively. It was also 8.7× weaker than S-verapamil as an agonist of somatostatin receptor type 2 (SSTR2), inhibiting ileal neurogenic contraction. Hence, R-verapamil may be an optimal DM treatment as it is safe, improves glycemic control, and preserves β-cell function both as monotherapy and in combination with metformin or acarbose. R-Verapamil has potential for delaying or arresting DM progression and improving patients’ quality of life.

This paper explores the impact of low-carbon service operations on responsible tourist behavior within sustainable cultural tourism. A proposed conceptual framework is used to examine this largely ignored situation through the case study of Xiao Liuqiu Island. The small island in Taiwan reveals a previously understudied phenomenon in sustainable island tourism. The psychological processes connecting cultural and cross-cultural experiences with sustainable tourism are explored using primary and secondary data collected through in-depth interviews of domestic tourists and online reviews of foreign tourists, respectively. Data analysis reveals the significant result that sustainable island tourism comprises two important elements: a supply and a demand side of a destination. The supply side describes low-carbon service operations—which include food, lodging, and ecological tourist activities—while the demand side reflects tourist behaviors—expressed through cognition, emotion, and motivation as well as authenticity. In addition, this paper makes an important contribution to management by emphasizing the need for careful attention to tourism psychology, particularly in natural and ecological environments that use tourism as a marketing strategy in cultural ecosystems services (CES).

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