Source Analysis of Heavy Metal Pollution Using UNMIX and PMF Models in Soils along the Shuimo River in Urumqi, China.

Eight kinds of heavy metals in soil within 0-2 km from the banks of Shuimo River in Urumqi were analyzed by using an X-ray fluorescence spectrometer and national standard detection methods. Unmix and PMF models are comprehensively used to analyze potential pollutant sources and contribution rates. Soil samples are sampled in three layers of 0-20, 20-40, and 40-60 cm, and each group of sample points in each layer is 5 m, 1 km, and 2 km away from the riverbank, respectively. Only the average concentration of Mn in each layer of soil is lower than the background value, according to the analytical results, while the average concentration of other heavy metals surpasses the background value. The highest proportion of exceeding the background value is Ni in the 40-60 cm soil layer, up to 1.92 times. Unmix and PMF models are used to analyze pollutants' source quantity and contribution rate, respectively. The results show that the two models can identify two pollution sources at the three soil layers, and their contribution rates are similar, and each index of the analysis results of the two models is within the required range of model reliability. By comparing with the Pearson correlation coefficient and distribution map of heavy metal concentration in surface soil, it is concluded that Zn, Pb, Cr, and Cu are mainly from industrial sewage and air pollution from coal combustion, while As, Mn, Ni, and V are mainly from agricultural pollution and light industrial pollution. In future research, it is necessary to investigate the change of heavy metal concentration in detail from the time dimension to further quantitatively calculate the potential pollutant source and contribution rate.

Relationship between Pleth Variability Index and the Occurrence of Hypotension during Epidural Anesthesia for Cesarean Section.

OBJECTIVE: To determine the predictive effect of pleth variability index（PVI）before anesthesia on hypotension after epidural anesthesia in cesarean section parturient women. STUDY DESIGN: Observational study. PLACE AND DURATION OF STUDY: Gansu Province People's Hospital, China, from March 2019 to May 2020. METHODOLOGY: One hundred and seven singleton parturient women, who underwent elective cesarean section, were selected. They were divided into no hypotension group (Group A) and hypotension group (Group B). Hypotension was defined as systolic blood pressure lower than 90 mmHg or >30% decrease in the mean arterial pressure. Receiver operating characteristic (ROC) curve was used to evaluate the predictive value of PVI before anesthesia and heart rate (HR) for hypotension after epidural anesthesia. RESULTS: After epidural anesthesia, 41 (38.32%) parturient women had hypotension. Basic values of HR and PVI before anesthesia in Group B were significantly higher than Group A (both p <0.001). The area under the ROC curve (AUC) of PVI basic value predicting hypotension was 0.824 (95% CI: 0.746-0.903, p <0.001), was greater than the AUC of HR basic value predicting hypotension, and the sensitivity and specificity of predicting hypotension were 92.7% and 66.7%, respectively. CONCLUSION: The PVI and HR values before anesthesia have certain value in predicting hypotension after epidural anesthesia in cesarean section. PVI value before epidural anesthesia has more clinical significance than the HR. Key Words: Pleth variability index (PVI, Heart rate (HR), Epidural anesthesia, Cesarean, Hypotension.

Nrf2/antioxidant defense pathway is involved in the neuroprotective effects of Sirt1 against focal cerebral ischemia in rats after hyperbaric oxygen preconditioning.

Sirtuin 1 (Sirt1) is a class III histone deacetylase involved in neuroprotection induced by hyperbaric oxygen preconditioning (HBO-PC) in animal models of ischemia. However, the underlying mechanisms remain to be illustrated. In the present study, rats exposed to middle cerebral artery occlusion (MCAO) were used to establish an ischemic stroke model. The infarct volume ratio, neurobehavioral score, and expressions of Sirt1, nuclear factor erythroid 2-related factor 2 (Nrf2), heme oxygenase 1 (HO-1), and superoxide dismutase 1 (SOD1) were evaluated at 7 days after reperfusion, and the level of malondialdehyde (MDA) was used to assess oxidative stress. HBO-PC increased the expression of Sirt1 and reduced infarct volume ratio and neurobehavioral deficit in MCAO rats. Meanwhile, HBO-PC also increased expression of Nrf2, HO-1, and SOD1 and decreased MDA content. Furthermore, either Sirt1 or Nrf2 knockdown by short interfering RNA (siRNA) inhibited the expression of Nrf2, HO-1, and SOD1 and eliminated the neuroprotective effects of HBO-PC. Taken together, the results suggest that the Nrf2/antioxidant defense pathway is involved in the long lasting neuroprotective effects of Sirt1 induced by HBO-PC against transient focal cerebral ischemia.