[Analysis on dynamical mechanism of multi outbreaks of COVID-19].

Objective: In the context of COVID-19 pandemic, the epidemic severities, non-pharmaceutical intervention intensities, individual behavior patterns and vaccination coverage vary with countries in the world. China has experienced a long period without indigenous cases, unfortunately, multi local outbreaks caused by imported cases and other factors have been reported, posing great challenges to COVID-19 prevention and control in China. Thus it is necessary to explore the mechanisms of the re-emerged COVID-19 epidemics and their differences. Methods: Based on susceptible exposed infectious recovered (SEIR) epidemic dynamics model, we developed a set of novel evolution equations which can describe the dynamic processes of integrated influence of interventions, vaccination coverage and individual behavior changes on the re-emergency of COVID-19 epidemic. We developed methods to calculate the optimal intervention intensity and vaccination rate at which the size of susceptible population can be reduced to less than threshold for the re-emergency of COVID-19 epidemic. Results: If strong interventions or super interventions are lifted too early, even a small cause can lead to the re-emergence of COVID-19 epidemic at different degrees. Moreover, the stronger the early control measures lifted are, the more severe the epidemic is. The individual behavior changes for the susceptibility to the epidemic and the enhancement or lifting of prevention and control measures are key factors to influence the incidence the multi outbreaks of COVID-19. The optimist early intervention measures and timely optimization of vaccination can not only prevent the re-emergency of COVID-19 epidemic, but also effectively lower the peak of the first wave of the epidemic and delay its arrival. Conclusion: The study revealed that factors for the re-emergence of COVID-19 epidemics included the intensity and lifting of interventions, the change of individual behavior to the response of the epidemic, external incentives and the transmissibility of COVID-19.

The use of transcallosal-interforniceal approach for microsurgical removal of the third ventricle tumors.

AIM: The third ventricle is located deep in the brain and is adjacent to important neurovascular structures. This makes tumor resection in this region difficult and causes more postoperative complications than surgeries in other regions of the brain. The objective of this study was to investigate the feasibility and clinical effects of transcallosal-interforniceal approach for microsurgical removal of the third ventricle tumors. METHODS: After preoperative evaluation, 23 patients with the third ventricle tumors were microsurgically operated using the transcallosal-interforniceal approach. RESULTS: Of these 23 patients, 12 (52.2%) underwent total excision, 9 (39.1%) had subtotal resection, and the remaining 2 (8.7%) underwent partial excision. After surgery, the following complications were observed: diabetes insipidus (11 patients), hemorrhages of the upper digestive tract (2 patients), central fever (1 patient), and memory impairment (1 patient). No mortality in the perioperative period was reported. CONCLUSION: The surgical procedure using the transcallosal-interforniceal approach is direct and provides good surgical field exposure and fewer post operational compilations. This approach should be considered as the method of choice for surgical removal of the third ventricle tumors.

Association of polymorphisms of the xeroderma pigmentosum complementation group F gene with increased glioma risk.

We aimed to investigate the role of 4 single nucleotide polymorphisms of the xeroderma pigmentosum complementation group F (XPF) gene (rs3136038, rs1799798, rs1800067, and rs2276466) in glioma, and the roles of gene-gene interactions in the risk of developing this type of cancer. We collected samples from 225 glioma cases and 262 controls and genotyped the rs3136038, rs1799798, rs1800067, and rs2276466 polymorphisms using a 384-well plate format with the Sequenom MassARRAY platform. Individuals carrying the rs1800067 GG genotype were more likely to have an increased risk of glioma when compared with carriers of the A/A genotype in a co-dominant model, with an odds ratio (OR) [95% confidence interval (CI)] of 2.85 (1.14-7.76). However, we did not find an association with increased risk of glioma for the polymorphisms rs3136038, rs1799798, and rs2276466 in XPF. The combination genotype of the rs1800067 G allele and the rs2276466 G allele was associated with a moderate risk of glioma (OR = 1.71, 95%CI = 1.02-2.87). Our study suggests that the rs1800067 genetic variant of XPF functions in the development of glioma.