Objective To investigate the effects of terahertz(THz)radiation on mouse testicular tissue and its potential molecular mechanisms.Methods A total of 125 male C57BL/6J mice(6～8 weeks old)were randomly divided into control group and low-,medium-and high-radiation power groups.The mice of the latter 3 groups were exposed to THz radiation at a frequency of 2.5 T,with an average power density of 38,115,or 318 mW/cm2,for 5 or 10 min.The detection time was immediately or 24 h after exposure.HE staining was used to observe pathological damage.ELISA was employed to detect the expression of inflammatory factors in testicular tissue.RNA-seq was utilized to detect the global changes of gene expression.The differentially expressed genes(DEGs)were screened and bioinformatics was used to cluster them.The screened genes were further analyzed with RT-qPCR to determine the time-dependent and dose-dependent relationships of the expression with THz exposure.Finally,sperm quality was evaluated morphologically using a microscope.Results Three doses of THz radiation exposure did not cause significant pathological damages to mouse testicular tissue.TNF-α expression was increased immediately after exposure at average power density of 115 mW/cm2(P＜0.01),and the expression of IL-1β and TNF-α were both increased when the dose reached 318 mW/cm2(P＜0.01).However,all the 3 factors returned to normal levels in 24 h after exposure.RNA-seq results showed that THz radiation exposure caused abnormal expression of 56 genes.Cluster analysis indicated that these DEGs were mainly enriched in immune and inflammatory responses,enzyme activity,sperm development and capacitation functions.Then for 5 selected key genes,Crisp1,Adam7,Ltf,Rnase9,and Bsph1,the expression of Crisp1 and Rnase9 was decreased immediately after exposure to 115 mW/cm2 THz radiation,the dose of 318 mW/cm2 resulted in obvious changes in the expression of the 5 genes(P＜0.05),and their expression returned to normal levels in 24 h after exposure.Morphological observation displayed that exposure to all the 3 doses of THz had no influence on sperm quality.Conclusion THz radiation exposure causes temporary inflammatory response in testicular tissue and abnormal expression of sperm functions-related genes.However,these changes return to normal 24 h after exposure,and additionally,do not impair sperm quality.

Aristolochic acid (AA), extracted from Aristolochiaceae plants, plays an essential role in traditional herbal medicines and is used for different diseases. However, AA has been found to be nephrotoxic and is known to cause aristolochic acid nephropathy (AAN).AA-induced acute kidney injury (AKI) is a syndrome in AAN with a high morbidity that manifests mitochondrial damage as a key part of its pathological progression. Melatonin primarily serves as a mitochondria-targeted antioxidant. However, its mitochondrial protective role in AA-induced AKI is barely reported. In this study, mice were administrated 2.5 mg/kg AA to induce AKI. Melatonin reduced the increase in Upro and Scr and attenuated the necrosis and atrophy of renal proximal tubules in mice exposed to AA. Melatonin suppressed ROS generation, MDA levels and iNOS expression and increased SOD activities in vivo and in vitro. Intriguingly, the in vivo study revealed that melatonin decreased mitochondrial fragmentation in renal proximal tubular cells and increased ATP levels in kidney tissues in response to AA. In vitro, melatonin restored the mitochondrial membrane potential (MMP) in NRK-52E and HK-2 cells and led to an elevation in ATP levels. Confocal immunofluorescence data showed that puncta containing Mito-tracker and GFP-LC3A/B were reduced, thereby impeding the mitophagy of tubular epithelial cells. Furthermore, melatonin decreased LC3A/B-II expression and increased p62 expression. The apoptosis of tubular epithelial cells induced by AA was decreased. Therefore, our findings revealed that melatonin could prevent AA-induced AKI by attenuating mitochondrial damage, which may provide a potential therapeutic method for renal AA toxicity.

Objective:To analyze the epidemiological characteristics of novel coronavirus positive cases including confirmed cases with clinical symptoms and asymptomatic infected cases in Guangzhou.Methods:Epidemiological data were collected on the nucleic acid positive cases of COVID-19 in Guangzhou from January to September 2020. The epidemiological characteristics, the distribution of time intervals between the confirmed/isolation date and the date of the first positive detection were analyzed, at last the influencing factors for the confirmed cases and asymptomatic infected persons were discussed.Results:From January 7 to September 4 in 2020, a total of 1 097 nucleic acid positive cases were identified, including 658 confirmed cases (59.98%) and 439 asymptomatic infected cases (40.02%). Among the 658 confirmed cases, the median age was 42 years old, the cases indicated two significant peaks. one of the peaks was related to the imported and associated cases from Hubei province, and the other peak was connected with individuals from overseas. In terms of 439 asymptomatic infected cases, the median age was 32 years old. There were two stages in these cases. The first stage followed the second peak of confirmed cases, and the second stage overlapped with the confirmed cases in Guangzhou when the epidemic was in a period of normal prevention and control, mainly related to imported cases from abroad. The asymptomatic infected persons accounted for 57.32% in all the imported infected cases. In both of asymptomatic and symptomatic cases, the positive rate of pharyngeal swabs was higher than that of nasopharyngeal swabs and anal swabs. There were statistically significant differences in age, source of infection and gender composition between confirmed cases and asymptomatic infected persons ( P<0.05). Older age groups were more likely to have clinical symptoms, with ≥40 years being the risk factor for confirmed cases (OR=2.334, P=0.001), and 20-39 years less likely to have clinical symptoms (OR=0.620, P=0.047), compared with the 0-19 years old group. Compared with those infected in China, those infected abroad were less likely to develop clinical symptoms and became confirmed cases (OR=0.723, P=0.013). Women were more likely to have clinical symptoms than men (OR=1.574, P=0.001). Conclusions:At present, asymptomatic infected persons and confirmed patients with clinical symptoms co-existed, and the number of asymptomatic infected patients was higher than that of confirmed cases in Guangzhou. High age, domestic infection and female may be risk factors for confirmed cases. It was of great value to further explore these underlying mechanisms for the prevention and treatment of the COVID-19.

Objective: To explore the cumulative effects of unintentional injury among children in rural area, in order to provide information for early intervention of unintentional injury. Methods: Through multistage clustering sampling method, 2 109 primary caregivers of students from 8 rural primary and elementary schools of Heilongjiang Province were recruited. Strengths and Difficulties Questionnaire (SDQ), Injury Behavior Checklist (IBC), Perceptions of Risks and Hazards were used to collect as the risk factors, while Perceptions of Risks and Hazards (PSAPQ), Home Observation for Measurement of the Environment (HOME) and Knowledge, Attitude and Practice for Children Unintentional Injury (KAP) were also used as the protective factors. Risk factors index (RFI) and protective factors index (PFI) were computed in the study. Results: The severity of unintentional injury were positively correlated with SDQ, IBC and perceptions of risks and hazards(r=0.15, 0.23, 0.12, P<0.01), and were negatively correlated with HOME, PSAPQ and KAP(r=-0.25, -0.14, -0.09, P<0.01). Hierarchical linear regression showed that the total scores of SDQ, IBC and environmental of HOME predicted the severity of unintentional injury which could explain 34% variant of unintentional injury. It also indicated that the severity of unintentional injury were positively correlated with RFI (β=0.21) and negatively correlated with PFI(β=-0.18), the interaction was significant(β=-0.11,R2=0.31)(P<0.01). Conclusion Both risk and protective factors of unintentional injury have cumulative effects on the severity of injury among rural children. The relationship between risk factors and injury could be mediated by protective factors.

Objective:To analyze the contagiousness and secondary attack rate of 2019 novel coronavirus in cluster epidemics in Guangzhou and provide evidence for the prevention and control of COVID-19.Methods:All the individuals identified to be infected with 2019-nCoV in Guangzhou, including confirmed cases and asymptomatic cases, were included and classified as imported cases and local cases. The first case of each cluster epidemic was defined as index case, and the number of subsequent infections was calculated to evaluate the contagiousness and secondary attack rate of 2019 novel coronavirus in the shortest incubation period of 1-3 days.Results:As of 18 February, 2020, a total of 349 cases of 2019-nCoV infection, including 339 confirmed cases (97.13 %) and 10 asymptomatic cases (2.87 %) were reported in Guangzhou. There were 68 clusters involving 217 2019-nCoV infection cases (210 confirmed cases and 7 asymptomatic cases). The median number of subsequent infections caused by an index case in a cluster epidemic was 3, among which 2 were confirmed cases and 1 was asymptomatic cases, respectively. The average number of contagiousness was 2.18 in shorted incubation period of 1-3 days (The average number of infected cases were 2.18 cases by the index case in a cluster epidemic), the average infection number in family members was 1.86, and the infection ratio of family member transmission was 85.32 % (1.86/2.18). The secondary attack rate in close contacts with shortest incubation period of 1-3 days was 17.12 %-18.99 %, the secondary attack rate in family members was 46.11 %-49.56 %. Conclusions:The cluster epidemic of COVID-19 in Guangzhou mainly occurred in families, the contagiousness was high. It is necessary to strengthen the prevention and control to reduce the community transmission of COVID-19.

Since the outbreak of COVID-19, it has spread rapidly throughout the country and even in the world. As a first tier city, Guangzhou is also the South Gate of China, with large population mobility and severe and complex prevention and control situation. Guangzhou CDC, together with Tencent and Alibaba Cloud, has made full use of its artificial intelligence technology to carry out a series of practices in case transmission chain analysis, close contact and other key personnel management, front-line staff prevention and control skills training and convenience services. Through the application of artificial intelligence in different scenarios, the difficulties and challenges in the prevention and control are solved, and the speed of epidemic prevention and control is increased.

Since the outbreak of COVID-19, it has spread rapidly throughout the country and even in the world. As a first tier city, Guangzhou is also the South Gate of China, with large population mobility and severe and complex prevention and control situation. Guangzhou CDC, together with Tencent and Alibaba Cloud, has made full use of its artificial intelligence technology to carry out a series of practices in case transmission chain analysis, close contact and other key personnel management, front-line staff prevention and control skills training and convenience services. Through the application of artificial intelligence in different scenarios, the difficulties and challenges in the prevention and control are solved, and the speed of epidemic prevention and control is increased.

Objective: To investigate the clinicopathologic features and grading of adenoid cystic carcinoma (ACC) of the breast. Methods: Sixteen cases of ACC of the breast were analyzed and graded according to the previous report. Immunohistochemical (IHC) staining was used to detect the immunophenotype, Ki-67 proliferative index and expression of EZH2, and the association with tumor grade and outcome was analyzed. Results: Of the 16 cases, 11 were grade Ⅰ, with the epithelial and myoepithelial cells being arranged into tubular and cribriform structure with no solid component; three were grade Ⅱ, which were composed of mixed tubular, cribriform and solid component (<30%); and two were grade Ⅲ, which showed mainly solid component (>90%) and the tumor cells showed basaloid features with scanty cytoplasm and hyperchromatic nuclei, and mitotic count was>5/10 HPF. Immunophenotypically, the epithelial cells expressed CK7, CK8/18 and CD117; the myoepithelial cells expressed p63 and CK5/6; while the basaloid cells were positive for CK5/6 and CD117.Tubular and cibriform ACC showed low Ki-67 and EZH2 expression, while the two cases of solid variant with basaloid features showed high level of Ki-67 and EZH2 expression. Follow-up data were available in 13 cases with a median follow-up period of 42 months. Lung metastasis occurred after 12 months in one grade Ⅱ case and the patient died of disease after 34 months. Vertebral metastasis occurred after 12 months in one grade Ⅲ case and axillary lymph node metastasis occurred in another grade Ⅲ case. All other patients were free of disease at the end of the follow-up periods. Conclusions ACC shows morphologic spectrum varying from low to high grade, the latter can may give rise to local and distant metastasis. ACC should not be regarded simply as low malignant potential, and should be graded for optimal treatment.

Objective Colloidal palladium was used as chemical modifier in the determination of blood thallium by graphite furnace atomic absorption spectrometry.Methods Blood samples were precipitated with 5％ (V/V) nitric acid,and then determined by GFAAS with colloidal palladium used as a chemical modifier.0.2％ (W/V) sodium chloride was added in the standard series to improve the matrix matching between standard solution and sample.Results The detection limit was 0.2 μg/L.The correlation coefficient was 0.9991.The recoveries were between 93.9％ to 101.5％.The relative standard deviations were between 1.8％ to 2.7％.The certified reference material of whole blood thallium was determined and the result was within the reference range Conclusion The method is accurate,simple and sensitive,and it can meet the needs of detection thallium in blood entirely.

Objective Colloidal palladium was used as chemical modifier in the determination of blood thallium by graphite furnace atomic absorption spectrometry.Methods Blood samples were precipitated with 5％ (V/V) nitric acid,and then determined by GFAAS with colloidal palladium used as a chemical modifier.0.2％ (W/V) sodium chloride was added in the standard series to improve the matrix matching between standard solution and sample.Results The detection limit was 0.2 μg/L.The correlation coefficient was 0.9991.The recoveries were between 93.9％ to 101.5％.The relative standard deviations were between 1.8％ to 2.7％.The certified reference material of whole blood thallium was determined and the result was within the reference range Conclusion The method is accurate,simple and sensitive,and it can meet the needs of detection thallium in blood entirely.