The PIWI family members are defined as conserved PAZ and PIWI domains and play important roles in stem-cell self-renewal,spermatogenesis,RNA interference and translational regulation.Recent researches have showen that some PIWI are specifically expressed in tumors and associated with tumor development and growth.PIWI is likely to be a new significante index for tumor diagnose and prognosis,the feasibility of PIWI acting in tumor gene theropy could be in vestigated by studying the mechanism of PIWI expression and regulation.

Objective: Based on physical activity (PA) and sedentary behavior (SB) variables on weekdays and weekends, the study aims to cluster the physical activities inside and outside kindergartens and to explore the cluster characteristics of different children using physical fitness indicators, so as to provide new strategies and methods for early childhood education and health. Methods: From March to June 2019, 291 children aged 3-6 years from 6 kindergartens in Nanchang were recruited by a stratified cluster random sampling method. The ActiGraph GT3X-BT triaxial accelerometer was used to measure and analyze the PA and SB levels inside and outside the kindergarten. A twostep clustering algorithm model was employed for cluster analysis. Physical fitness were measured and evaluated according to the "National Physical Fitness Measurement Standard Manual (Preschool Section)". Differences in physical fitness among different clusters of children were compared, and the cluster characteristics of different children were analyzed. Results: The clustering algorithm model indicated that based on six indicators, including PA and SB inside the kindergarten on weekdays, and PA and SB outside the kindergarten on both weekdays and weekends, children could be divided into three categories:active inside (high PA, low SB inside), active outside (high PA outside), and inactive (low PA, high SB both inside and outside). The average silhouette coefficient of the model was 0.3, indicating good clustering results. Both the active inside and active outside children showed significantly higher PA inside on weekdays, PA outside on weekdays and weekends, daily low intensity physical activity (LPA) and moderate-to-vigorous physical activity (MVPA) than the inactive children ( F=157.91, 80.79 , 95.86, 95.52, 124.74, P <0.05). After adjusting for gender and age, the physical fitness scores of both active outside ( 19.03 ±0.47) and active inside (19.11±0.40) were significantly higher than those of the inactive children (17.94±0.31). Additionally, active inside children (3.91±0.14) also showed significantly better performance in continuous double-leg jumps, compared to inactive children (3.45±0.11) ( P <0.05). Conclusion Children active inside and those active outside perform well in PA. Future research should focus on the proportion of structured and unstructured PA time to enhance the overall physical fitness of children.

【Objective】 To construct an acute toxoplasma encephalitis mouse model by observing the pathological changes in the hippocampus of mice infected with Toxoplasma gondii strain RH. 【Methods】 The quantitative RH Toxoplasma gondii (100, 500, and 1 000 trophozoites) were injected into the hippocampal CA1 region of mice by the stereotaxic surgery; the survival status of mice was observed. Giemsa staining was used to observe the changes of toxoplasma in mouse ascites and brain tissue homogenates. Nissl staining and HE staining were used to observe the pathological changes of hippocampal nerve tissue. The distribution of Toxoplasma gondii in brain tissue was observed by immunohistochemical ABC method. 【Results】 The RH Toxoplasma gondii infected mice showed obvious symptoms such as arched back, bristling hair, abdominal distension, subtle tremor and hemiplegia on the fourth day of infection. The survival of mice in 100 trophozoites group was longer, no trophozoites of Toxoplasma gondii were found in ascites, a few pseudocysts were found in brain tissue homogenates after infected for 96 hours, and more trophozoites were found after death. Nysl staining and HE staining showed more tissue necrosis foci and loss of nerve cells in CA1 area after infected 144 h. The injury aggravated with the prolongation of infection time. Toxoplasma trophozoites were found in ascites and brain homogenates of mice in 500 and 1000 trophozoites groups. Nissl staining revealed neuronal loss and massive necrosis in the hippocampus. HE staining showed necrosis and inflammatory cell infiltration. The brain tissue injury significantly aggravated compared with 100 trophozoites group. The distribution of Toxoplasma gondii in the necrotic foci was confirmed by immunohistochemistry. 【Conclusion】 The survival of 100 trophozoite mice infected with Toxoplasma gondii strain RH was longer, and the pathological changes of brain tissue gradually aggravated. The damage was relatively confined to the brain tissue, and the mice showed typical symptoms of toxoplasma encephalitis. Therefore, the mouse model of acute toxoplasma encephalitis can be constructed by localized infection of 100 toxoplasma trophozoites, which can lay a foundation for future research on the mechanism of toxoplasma injury to cranial nerves.

The coronavirus disease 2019 (COVID-19) has caused a global pandemic. All people including children are generally susceptible to COVID-19, but the condition is relatively mild for children. The diagnosis of COVID-19 is largely based on the epidemiological evidence and clinical manifestations, and confirmed by positive detection of virus nucleic acid in respiratory samples. The main symptoms of COVID-19 in children are fever and cough; the total number of white blood cell count is usually normal or decreased; the chest imaging is characterized by interstitial pneumonia, which is similar to other respiratory virus infections and infections. Early identification, early isolation, early diagnosis and early treatment are important for clinical management. The treatment of mild or moderate type of child COVID-19 is mainly symptomatic. For severe and critical ill cases, the oxygen therapy, antiviral drugs, antibacterial drugs, glucocorticoids, mechanical ventilation or even extracorporeal membrane oxygenation (ECMO) may be adopted, and the treatment plan should be adjusted timely through multi-disciplinary cooperation.
Betacoronavirus ; isolation & purification ; Child ; Coronavirus Infections ; diagnosis ; pathology ; therapy ; Humans ; Pandemics ; Pneumonia, Viral ; diagnosis ; diagnostic imaging ; etiology ; pathology ; therapy

Betacoronavirus ; isolation & purification ; Child ; Clinical Laboratory Techniques ; Coronavirus Infections ; diagnosis ; drug therapy ; therapy ; Humans ; Pneumonia, Viral ; diagnosis ; therapy