Synergism in sequential inactivation of Cryptosporidium parvum with trypsin and UV irradiation.

Cryptosporidium, a protozoan parasite, in wastewater presents a major public health concern for water safety. However, bactericidal efficiencies of conventional disinfection methods towards Cryptosporidium oocysts are still hampered owing to the presence of their thick outer wall. In this study, we present a novel UV inactivation process where the efficiency has been significantly enhanced by addition of a trypsin pretreatment stage. Notably, inactivation (log-reduction) of oocysts was noted to be 73.75-294.72% higher than that obtained by UV irradiation alone, under identical conditions. Experimental observations and supporting mechanistic analyses suggest that trypsin led to cleavage of the protein layers on the oocyst wall, facilitating penetration of UV radiation into the oocysts leading to degradation of their genomic DNA (gDNA). The dissociative effect of trypsin on the oocyst wall was indicated by the fact that 64.50% of oocysts displayed early apoptosis after trypsinization. Imaging by scanning electron microscopy indicated that this combined treatment led to substantial disruption of the oocyst coat, deforming their shape. This resulted in the release of cellular proteins and gDNA, their concentrations in bulk solution increasing by 1.22-8.60 times. As UV irradiation time was prolonged, gDNA was degraded into smaller fragments with lower molecular masses. Both laddering and diffuse smear patterns in gel analysis indicated significantly detrimental effects on gDNA and viability of oocysts. Overall, this study demonstrated enhancement of UV inactivation of Cryptosporidium oocysts by trypsin and explored the underlying mechanisms for the process.

Application of machine learning to predict the inhibitory activity of organic chemicals on thyroid stimulating hormone receptor.

With the promotion of carbon neutrality, it is also important to synchronously promote the assessment and sustainable management of chemicals so as to protect public health. Humans and animals are possibly exposed to endocrine disruptors that have inhibitory effects on thyroid stimulating hormone receptor (TSHR). As such, it is important to identify chemicals that inhibit TSHR and to develop models to predict their inhibitory activity. In this study, 5952 compounds derived from a cyclic adenosine monophosphate (cAMP) analysis, a key signaling pathway in thyrocytes, were used to establish a binary classification model comparing methods that included random forest (RF), extreme gradient boosting (XGB), and logistic regression (LR). The prediction model based on RF showed the highest identification accuracy for revealing chemicals that may inhibit TSHR. For the RF model, recall was calculated at 0.89, balance accuracy was 0.85, and its receiver operating characteristic (ROC) curve-area under (AUC) was 0.92, indicating that the model had very high predictive capacity. The lowest CDocker energy (CE) and CDocker interaction energy (CIE) for chemicals and TSHR were determined and were subsequently introduced into the predictive model as descriptors. A regression model, extreme gradient boosting-Regression (XGBR), was successfully established yielding an R2 = 0.65 to predict inhibitory activity for active compounds. Parameters that included dissociation characteristics, molecular structure, and binding energy were all key factors in the predictive model. We demonstrate that QSAR models are useful approaches, not only for identifying chemicals that inhibit TSHR, but for predicting inhibitory activity of active compounds.

[Benefits of promoting male circumcision among the general population in the high HIV prevalence areas of Guangxi Province].

OBJECTIVE: To evaluate the effect of promoting male circumcision among the general population in the high HIV prevalence areas of Guangxi Province. METHODS: We interviewed 590 male residents from Hezhou and Qinzhou areas of Guangxi Province and conducted intervention using male circumcision promotion materials and various methods. If the subjects were willing and had no contraindication, they were referred to the appointed hospitals to receive circumcision. We conducted follow-up visits at 6 and 9 months after intervention for the changes in the subjects' knowledge, attitude and practice related to male circumcision. RESULTS: The male circumcision knowledge, willingness and operation rate were significantly improved after intervention (P < 0.05), but with no significant difference between the two follow-up visits (P > 0.05). The number of those who knew that phimosis and redundant prepuce were the reasons for circumcision increased from 66.1% at baseline to 81.9% and 79.8% at the two follow-up visits; those who knew that circumcision could prevent AIDS and sexually transmitted diseases increased from 28.0% to 77.4% and 78.6%; those who knew that surgical complications could be pain, bleeding and infection increased from 29.5%, 19.3% and 39.3% to 72.5%, 58.2% and 59.4% at the first follow-up and 75.0%, 57.0% and 63.0% at the second; those who were willing to receive circumcision increased from 35.3% at baseline to 59.6% and 61.3% at the two follow-up visits; and the rate of surgery increased from zero to 12.7% and 16.1%. CONCLUSION: The promotion of male circumcision among the general population in the high HIV prevalence areas of Guangxi Province significantly improved their knowledge, attitude and practice related to AIDS prevention. And the promotion activities should focus on the publicity of AIDS knowledge, risks of phimosis and redundant prepuce, and safety of circumcision.