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Abstract The HIV/AIDS cases and proportion in older people are continuously and rapidly increasing in China, especially in males. However, the transmission mechanism is not well understood. This study aims to explore the transmission mechanism of HIV/AIDS and potential ways to prevent or control HIV/AIDS transmission in a city in southwestern China. Data from multiple sources, including HIV/AIDS case reports in 2010–2020, a survey of HIV/AIDS cases in 2020, and sentinel surveillance data of female sex workers (FSWs) in 2016–2020 were analyzed. We explored the transmission mechanism of HIV/AIDS cases aged 50 years and older. In this city, the number of newly reported HIV/AIDS cases aged 50 years and older increased from 2010 to 2019, and decreased in 2020. The number of male and female cases aged 50 years and older both increased rapidly in 2017–2019, though the number of male cases was larger than that of female. The survey data showed that 84.7% of older male cases reported commercial sexual behavior, among whom 87.7% reported never using condom and 37.6% reported more than 10 times of commercial sexual behaviors in 1 year. In terms of price of sexual behavior, 68.3% of older male cases sought low-tier FSWs among whom the HIV/AIDS positive rate was 5.4% from the sentinel surveillance data. These results suggested HIV transmission between older men and low-tier FSWs through commercial sexual behavior. Among female cases aged 50 years and older, most reported non-marital and non-commercial heterosexual (60.5%) or regular sexual partner (31.4%) transmission, suggesting that they were infected by their spouse/regular sexual partner. Data of matched couples showed that most male cases had both marital sexual behavior and commercial sexual behavior, or acquired HIV through commercial sexual behavior, while most female cases had only marital sexual behavior. Based on these findings, we proposed a transmission mode of that local older male people and FSWs are transmitting bilaterally through commercial sexual behavior, and local older male people are spreading to local older female people through spouse or regular sexual partner route. By studying data from multiple sources, we explored the HIV transmission mode among older people. In the meantime, we found that marital status had a different impact on male and female old people in their sex behaviors.

Catestatin (CST) is a catecholamine secretion inhibiting peptide as non-competitive inhibitor of nicotinic acetylcholine receptor. CST play a protective role in cardiac ischemia/reperfusion (I/R) but the molecular mechanism remains unclear. Cardiomyocytes endogenously produced CST and its expression was reduced after I/R. CST pretreatment decreased apoptosis especially endoplasmic reticulum (ER) stress response during I/R. The protection of CST was confirmed in H9c2 cardiomyoblasts under Anoxia/reoxygenation (A/R). In contrast, siRNA-mediated knockdown of CST exaggerated ER stress induced apoptosis. The protective effects of CST were blocked by extracellular signal-regulated kinases 1/2 (ERK1/2) inhibitor PD90895 and phosphoinositide 3-kinase (PI3 K) inhibitor wortmannin. CST also increased ERK1/2 and protein kinase B (Akt) phosphorylation and which was blocked by atropine and selective type 2 muscarinic acetylcholine (M2) receptor, but not type 1 muscarinic acetylcholine (M1) receptor antagonist. Receptor binding assay revealed that CST competitively bound to the M2 receptor with a 50% inhibitory concentration of 25.7 nM. Accordingly, CST inhibited cellular cAMP stimulated by isoproterenol or forskolin, and which was blocked by selective M2 receptor antagonist. Our findings revealed that CST binds to M2 receptor, then activates ERK1/2 and PI3 K/Akt pathway to inhibit ER stress-induced cell apoptosis resulting in attenuation cardiac I/R injury. [ABSTRACT FROM AUTHOR]