Surface water quality in the upstream-most megacity of the Yangtze River Basin (Chengdu): 2000-2019 trends, the COVID-19 lockdown effects, and water governance implications

Water is essential for a sustainable economic prosperity, but rapid economic growth and intensive agricultural activities usually cause water pollution. The middle and lower reaches of China’s Yangtze River Basin were urbanized and industrialized much earlier than the upper reach and have been suffering from water pollution. In the past two decades, economic growth accelerated in the upper reach due to several national economic initiatives. Based on analyzing water quality changes from 2000 to 2019 and during the COVID-19 lockdown in 2020 for Chengdu in the upper reach, we hope to provide some water governance suggestions. In 2019, water at 66% of 93 sites in Chengdu did not achieve the national III standards using measurements of 23 water quality parameters. The top two pollutants were total nitrogen (TN) and fecal coliform (FC). From 2000 to 2019, water quality was not significantly improved at the non-background sites of Chengdu's Min Basin, and the pollution in this basin was mainly from local pollutants release. During the same period, water quality deteriorated in Chengdu’s Tuo Basin, where pollution was the result of pollutant discharges in Chengdu in addition to inter-city pollutant transport. During the COVID-19 lockdown, water quality generally improved in the Min Basin but not in the Tuo Basin. A further investigation on which pollution sources were shut down or not during the lockdown can help make pollution reduction targets. Based on the results, we provide suggestions to strengthen inter-jurisdictional and inter-institutional cooperation, water quality monitoring and evaluation, and ecological engineering application.

Semen quality and windows of susceptibility: A case study during COVID-19 outbreak in China.

BACKGROUND: To evaluate the impact of air pollution exposure on semen quality parameters during COVID-19 outbreak in China, and to identify potential windows of susceptibility for semen quality. METHODS: A retrospective observational study was carried out on 1991 semen samples collected between November 23, 2019 and July 23, 2020 (a period covering COVID-19 lock-down in China) from 781 sperm donor candidates at University-affiliated Sichuan Provincial Human Sperm Bank. Multivariate mixed-effects regression models were constructed to investigate the relationship between pollution exposure, windows of susceptibility, and semen quality, while controlling for biographic and meteorologic confounders. RESULT(S): The results indicated multiple windows of susceptibility for semen quality, especially sperm motility, due to ambient pollution exposure. Exposure to particulate matters (PM2.5 and PM10), O3 and NO2 during late stages of spermatogenesis appeared to have weak but positive association with semen quality. Exposure to CO late in sperm development appeared to have inverse relationship with sperm movement parameters. Exposure to SO2 appeared to influence semen quality throughout spermatogenesis. CONCLUSION(S): Potential windows of susceptibility for semen quality varied depending on air pollutants. Sperm motility was sensitive to pollution exposure. Findings from current study further elucidate the importance of sensitive periods during spermatogenesis and provide new evidence for the determinants of male fertility.

Challenges and potential for improving the druggability of podophyllotoxin-derived drugs in cancer chemotherapy.

Covering: up to 2020As a main bioactive component of the Chinese, Indian, and American Podophyllum species, the herbal medicine, podophyllotoxin (PTOX) exhibits broad spectrum pharmacological activity, such as superior antitumor activity and against multiple viruses. PTOX derivatives (PTOXs) could arrest the cell cycle, block the transitorily generated DNA/RNA breaks, and blunt the growth-stimulation by targeting topoisomerase II, tubulin, or insulin-like growth factor 1 receptor. Since 1983, etoposide (VP-16) is being used in frontline cancer therapy against various cancer types, such as small cell lung cancer and testicular cancer. Surprisingly, VP-16 (ClinicalTrials NTC04356690) was also redeveloped to treat the cytokine storm in coronavirus disease 2019 (COVID-19) in phase II in April 2020. The treatment aims at dampening the cytokine storm and is based on etoposide in the case of central nervous system. However, the initial version of PTOX was far from perfect. Almost all podophyllotoxin derivatives, including the FDA-approved drugs VP-16 and teniposide, were seriously limited in clinical therapy due to systemic toxicity, drug resistance, and low bioavailability. To meet this challenge, scientists have devoted continuous efforts to discover new candidate drugs and have developed drug strategies. This review focuses on the current clinical treatment of PTOXs and the prospective analysis for improving druggability in the rational design of new generation PTOX-derived drugs.