The two—flange compression screw is a new instrument developed by us. This nail consists of two parts, the two—flange plate part and the compression screw part. We used it to treat 67 cases of femoral neck fracture, aged 39～79 years in 1988 to 1992. In the 67 cases there were 12 cases with stage Ⅰ type fracture, 14 with stage Ⅱ type fracture, 24 with stage Ⅲ type fracture and 17 with stage Ⅳ type fracture. We followed—up 42 cases for 8 months to 3 years, with result of good unjon in 38 cases (90%), avascular necrosis of the femoral head in 2 (5% ) and non—union in (5%). The biomechanical research demonstrated that the two—flange compression screw had the function of resisting rotation and section compression.

Objective To observe the effect of estrogen on BBB permeability,occludin expression after ischemia-reperfusion in rats,and to make a further investigation on the role of estrogen in cerebral ischemia. Methods Ovariectomized rats were randomly divided into sham-operated group,model group,and estrogen pretreatment group. 4 h,24 h,3 d after ischemia-reperfusion were selected as different observation points,and changes of edema,occluding expression,and blood-brain barrier permeability of the 3 points in time were observed. BBB ultra-structure electron microscope observation was made at 24 h and 3 d after ischemia-reperfusion. Changes in cerebral edema were measured by brain water content percentage;protein expressions were measured by Western blot;and BBB permeability was measured by Evans blue as-say. Results Compared with the sham group,brain tissue water content and EB content in model group both increased 4 h after ischemia-reperfusion (P<0. 05),and they keep increasing as time goes by and finally reaching the peak (P<0. 01). Compared with the model group at the same time point,brain tissue water content and EB content in estrogen pretreatment group decreased in different degrees (P<0. 05 or P<0. 01),and it was most significant at the time point of 24 h after ischemia-reperfusion (P<0. 01). Compared with model group,through electron microscope observation,ia was displayed that BBB TJ's open was reduced in estrogen pretreatment group,astrocyte foot process and capillary tube edema were lighter,and it was significant at the time point of 3 d after ischemia-reperfusion. Western blot detection of occludin protein expression found that it was lower in the model group compared with the sham group at 4 h after ischemia-reperfusion,but there was no significant difference (P>0. 05). 24 h after ischemia-reperfusion,the occludin expression were weaker than that in the sham surgery group with a significant difference (P<0. 05),and it keep weakening with a significant difference 3 d after ischemia-reperfusion (P<0. 01). In estrogen group,there was no significant difference compared with the model group in terms of occludin expression at 4 h after ischemia-reper-fusion (P>0. 05). In estrogen group,there was significant difference in occludin protein expression at 24 h and 3 d after ischemia-reperfusion compared with model group at the same time point (P<0. 05). Conclusion BBB ultrastructure disclose TJ was broke and vesicles within EC was increased and astrocyte cell foot process was swelling in MCAO model,it might be the vasogenic brain edema pathological basis for MCAO. In MCAO animal model,with ischemia-reperfusion time increasing,TJ protein occludin expression significantly decreased,it suggests that occludin plays an important role in the regulation of TJ permeability. Estrogen increases has a very close relationship with occludin ex-pression,and it may be one of the mechanisms of protecting BBB integrity and lessening cerebral edema.

Objective:To investigate the clusters of COVID-19 associated with a market (market Y) in Haidian District, Beijing, and analyze the chain of transmission and provide reference for effective prevention and control of COVID-19.Methods:The investigation of field epidemiology and cluster epidemic was used to describe the distributions of all COVID-19 cases. The time sequence diagram of the cases, disease onset was drawn and transmission chains were analyzed. Real-time RT-PCR assay was conducted for SARS-CoV-2 nucleic acid test by using the respiratory samples of the cases.Results:The COVID-19 epidemic, originated from a wholesale farm produce market (market X) in Fengtai District, Beijing, was introduced by a marketer in the market Y who had exposed to market X, causing 8 clusters of 20 confirmed cases of COVID-19 and one asymptomatic case, including 8 men and 13 women, in market Y, surrounding communities, food plaza, companies,families and other places. The incidence peaked during June 10-14, 2020; the median age of the cases was 45 years, ranging from 5 years to 87 years. The initial symptoms of the cases included fever (10/20) and pharynx discomfort (7/20). The median of incubation period was 5 days ( IQR:3-8). The median of serial interval between primary case and secondary cases was 5 days with a secondary attack rate of 3.7%(20/538), and the secondary attack rate in household close-contacts was 14.0% (7/50). Conclusions:The clusters of COVID-19 associated with market Y were caused by several modes of transmission, including human-to-human, contaminated material-to-human, etc. The combined public-health response measures were effective to control the COVID-19 epidemic in Haidian district of Beijing.