The severe acute syndrome coronavirus 2(SARS-CoV-2)is responsible for the global pandemic of 2019 novel coronavirus disease(COVID-19). Understanding the pathogenic mechanisms of SARS-CoV-2 is of great significance to the prevention and control of the COVID-19 epidemic. The spike(S)protein of SARS-CoV-2 is a major target of protective immunity. The mutations of S protein impact the transmission and pathogenic capacity of SARS-CoV-2. In addition, angiotensin-converting enzyme 2(ACE2)is the receptor of SARS-CoV-2 S protein and mediates viral entry into target cells. The genetic polymorphisms of the ACE2 gene may lead to the difference of incidence of COVID-19 among different populations. Protease can promote the infection of SARS-Cov-2 by activating the S protein. This review summarized the current understanding of the function and genetic variants of S protein, ACE2, and the related proteases. The synergistic effect of these three molecules on the susceptibility of SARS-CoV-2 infection was further discussed.

·AIM:To compare the outer nuclear layer ( ONL) , inner and outer segments (IS/OS), photoreceptor cell layer in healthy people and diabetic retinopathy by frequency-domain optical coherence tomography ( OCT) .·METHODS: Totally 100 eyes of 50 healthy people were selected as control group. According to conventional mydriasis for examination of fundus and fundus fluorescein angiography ( FFA ) examination, all diabetic cases were divided into 3 groups: normal retina group ( NDR ) , non - proliferative diabetic retinopathy group (NPDR), proliferative diabetic retinopathy group (PDR). Using OCT measure the thickness of ONL, IS/OS and photoreceptor cell layer of fovea and parafovea ( nasal side and temporal side) in the four groups.·RESULTS: Compared with the control group, the ONL and photoreceptor cell layer's thickness of macular fovea and temporal parafovea in NPDR group and PDR group were statistically significant(all P<0. 05). The differences between ONL and photoreceptor cell layer's thickness of macular fovea and temporal parafovea in NDR group and PDR group were not statistically significant(P>0. 05). The IS/OS of macular fovea and temporal parafovea was not significantly different among those groups (P>0. 05). The thickness of different layers of nasal parafovea were not different (P>0. 05).·CONCLUSION: The thickness of macular fovea and temporal parafovea has relation with degree of DR; the change of photoreceptor cell layer's thickness occurs mainly in ONL, but IS/OS no change; the change in temporal parafovea more obvious than in nasal parafovea. Frequency-domain OCT can quantitatively and qualitatively observe the subtle diabetic macular changes in diabetic patients with macular disease, and provides a reliable detection for the early diagnosis and treatment.

Abstract：Objective To analyze the stabilities of neuraminidase（NA）in influenza vaccine at different temperatures and provide a reference for further complete understanding of overall shelf life of vaccines. Methods Monovalent bulks of influenza H1N1，H3N2 and B vaccines were stored at 4（low temperature），25（room temperature）and 37 ℃（changed temperature）for 0. 5，2，7，24 and 48 h separately，using that at 100 ℃（extreme temperature）for 1 h as control，and determined for NA activity by enzyme⁃linked lectin method. Results The NA activities of influenza H1N1 vaccines stored at 25 and 37 ℃ decreased significantly with the increasing of time. No significant decreases were observed in H3N2 and B vaccines even after storage at two non⁃storage temperatures for 48 h. However，all the NA activities of three vaccines decreased at 100 ℃. Conclusion Both H3N2 and B vaccines showed high stability at abnormal storage temperatures not more than 37 ℃，while H1N1 vaccine was relatively sensitive to the temperature for storage.

OBJECTIVETo investigate the blood lead status and influencing factors among preschool children in the sampling city.

METHODStratified-clustered-random sampling was used. Standardized questionnaire and peripheral blood samples were obtained from 69 968 children aged 0-6 years in fixed kindergartens and communities of Yinchuan, Xi'an, Chengdu, Wuhan, Hefei, Beijing, Harbin, Zhengzhou, Huhhot, Shijiazhuang, Haikou, Dalian, Qingdao, Guangzhou, Nanning and Changsha from 2004 to 2008, respectively. Tungsten atomic absorbtion spectrophotometry was employed to determine the blood lead level of children.

RESULTThe proportion of children with blood lead level ≥ 100 µg/L was 7.57% (among which the proportion of high blood lead level, mild lead poisoning, moderate lead poisoning, severe lead poisoning were 91.0%, 2.76%, 3.32%, 2.93%, respectively) and the blood lead level was lower than those of the past studies. The proportion of high blood lead level has steadily declined from 2004 to 2008 [the proportions were 10.03%, 7.85%, 7.40%, 6.91% and 4.78%, respectively (χ(2) = 297.36, P < 0.0001)]. The proportion of children with blood lead level ≥ 100 µg/L in Haikou, Zhengzhou, Guangzhou, Shijiazhuang, Changsha, Xi'an, Wuhan, Hefei, Chengdu, Yinchuan, Harbin, Beijing, Dalian, Huhhot, Nanning and Qingdao were 12.15%, 10.49%, 10.37%, 9.69%, 9.53%, 9.46%, 9.40%, 8.50%, 7.99%, 7.98%, 7.51%, 6.10%, 3.25%, 2.89%, 2.46% and 2.39%, respectively (χ(2) = 768.21, P < 0.0001). By multiple regression method, the risk factors which influenced blood lead status of children were education status of mother, older children, behavior and dietary habit of children, boy, stay for long time in traffic busy areas, the type of housing, taking traditional Chinese and herbal medicine. The protective factors against lead poisoning in children mainly included scattered living, the nutritional status of calcium, iron, zinc, frequent intake of milk, and older mother.

CONCLUSIONThe blood lead level of children has decreased, but is still higher than those in developed countries. Lead exposure remains a public health issue which affects children most. The blood lead level of children is affected by multiple factors. Government and the whole society should pay attention to interrupt the lead pollutant and to promote nutritional health education. With all these efforts, it is possible to stop the progress of lead exposure and reduce its hazardous effects on the growth and development of children.

Child ; Child, Preschool ; China ; epidemiology ; Female ; Humans ; Infant ; Lead ; blood ; Lead Poisoning ; epidemiology ; Male ; Risk Factors ; Surveys and Questionnaires ; Urban Population

OBJECTIVETo research the efficacy and feasibility for unstable fracture of thoracolumbar with AF spine internal fixation device.

METHODSThirty-two patients with unstable fractures of T11-L3 were treated with AF spine internal fixation device and autograft between vertebral lamina vertebral body transverse process from January 2002 to June 2006. There were 21 female and 11 male, aging from 58 to 72 years with a mean of 62 years. All these patients were examined with x-ray and CT preoperative and postoperative respectively. They were followed-up thirteen months averagely, observing the stability of spinal column, bone grafting fusion, the height of vertebra and recovery of anterior bone fragment herniation.

RESULTSAll these AF spine internal fixation devices treated for the unstable fractures of thoracolumbar had not removed because of internal fixation failure or pain. Fracture healing and grafting fusion appeared after operation three months averagely. X-rays revealed post-protrusion angle were recovered from 22 degrees to 8.5 degrees, the heights of anterior were recovered from 50% to 86%, the angle of posterior were recovered from 94% to 98%. The postoperative CT scan showed that six cases with herniation to canal gained a completely recoveries.

CONCLUSIONAF spine internal fixation device used in early stage for unstable fracture of thoracolumbar is a simple and effective method. It has advantages such as providing early substantial fixation, maintaining a well three column stability. Bone grafting is a key factor in this operative technique.

Aged ; Female ; Fracture Fixation, Internal ; methods ; Humans ; Lumbar Vertebrae ; injuries ; surgery ; Male ; Middle Aged ; Spinal Fractures ; surgery ; Thoracic Vertebrae ; injuries ; surgery

OBJECTIVETo investigate the blood lead level in children aged 0-6 years in urban areas of China.

METHODSFourteen cities were selected as sites under surveillance. A total of 44 045 peripheral blood specimens were collected from 2004 to 2006, during which 15 727, 14 737, and 13 584 specimens were tested in 2004, 2005, and 2006, respectively. Tungsten atomizer absorption spectrophotometer was employed to determine blood lead level.

RESULTSThe geometric mean blood lead level in the tested children was 47.10 microg/L with 10.10% > or = 100 microg/L, 46.17 microg/L with 7.78% > or = 100 microg/L, and 47.03 microg/L with 7.30% > or = 100 microg/L in 2004, 2005, and 2006, respectively. The blood lead levels seemed to tend to rise in parallel with the increase of age of the children and were higher in boys (48.84 microg/L, 47.56 microg/L, and 47.78 microg/L in the 3 respective years) than in girls (45.00 microg/L, 44.53 microg/L, and 46.13 microg/L).

CONCLUSIONThe blood lead levels in children in cities of China are lower than those in previous national studies, but higher than those in developed countries. Childhood lead poisoning remains a public health problem in China.

Age Distribution ; Child ; Child, Preschool ; China ; epidemiology ; Cities ; epidemiology ; Female ; Humans ; Infant ; Infant, Newborn ; Lead ; blood ; Lead Poisoning ; blood ; diagnosis ; epidemiology ; Male ; Population Surveillance ; Sex Characteristics

OBJECTIVETo observe blood lead level and related risk factors among children aged 0-6 years old living in cities in China and to provide data for policy development to the prevention on environmental lead pollution.

METHODSA stratified-clustered-random sampling method was used. 17 141 peripheral blood samples of 0-6 years old children from 15 cities in China were tested. Tungsten atomizer absorption spectrophotometer was employed to determined the blood lead level. Related factors were also studied using a standardized questionnaire. Data were analyzed on related risk factors that affecting blood lead levels through multiple regression method.

RESULTSThe mean blood lead level of 0-6 years old children from 15 cities in China was 59.52 microg/L including 10.45% of those > or =100 microg/L, and 0.62% > or = 200 microg/L. However, the blood lead levels seemed to have had a trend of increase parallel to age among 0-6 years-old children and were higher for boys (59.50 microg/L) than girls (54.95 microg/L). The risk factors which influenceing children's blood lead levels would include the type of housing, parent's education levels, social status and hobby, children's behavior habit, dieting habit and nutritional condition.

CONCLUSIONThe blood lead levels of children in China were lower than data gathered from former national studies but higher than those from developed countries, suggesting that the. Government and the whole society should be aware of the problem on lead poisoning among children during their childhood.

Child ; Child, Preschool ; China ; Female ; Health Policy ; Humans ; Infant ; Infant, Newborn ; Lead ; blood ; Logistic Models ; Male ; Quality Control ; Risk Factors ; Sampling Studies ; Urban Population ; statistics & numerical data

Objective To develop a new algorithm to reconstruct the distribution of acoustic sources of magnetoacoustic tomography with magnetic induction(MAT-MI)in the acoustic inhomogeneous media,which is developed on the basis of generalized finite element method (GFEM) and modified time inversion algorithm. Methods The acoustic and acoustic coupling theory and the basic equations of acoustics were used to study the forward and inverse problems of the acoustic inhomogeneous concentric sphere magneticacoustic coupling model. The solution of acoustic non-uniform media wave equation based on GFEM was proposed.The method solved the problem of acoustically inhomogeneous media sound source reconstruction and conductivity reconstruction.At the same time,the distribution of velocity was reconstructed by rotating the pairs of transducers and the time reversal algorithm. Results The proposed algorithm could accurately reconstruct the acoustic source distribution in acoustic inhomogeneous media,and could obtain the distribution of sound velocity during the reconstruction of sound source and recover the image well. Conclusion The proposed algorithm had its feasibility and effectiveness verified,and gains advantages in MAT-MI reconstruction of acoustic inhomogeneous media.

BACKGROUND:Temporomandibular joint disorders are closely related to high stress in temporomandibular joint.With the change of molar position after tooth reduction extraction,the establishment of new occlusal relationship often leads to the change of internal stress environment of the temporomandibular joint. OBJECTIVE:To analyze the stress distribution of temporomandibular joint in patients undergoing orthodontic reduction tooth extraction with different degrees of molar forward movement using the three-dimensional finite element model of the maxillary complex and temporomandibular joint. METHODS:A case of individual normal occlusal patient was selected from the Orthodontics Department of Qingdao Municipal Hospital,Shandong Province,and the finite element models of 1/3 anterior molar space(extraction of four second premolar teeth)before and after reduction and 2/3 anterior molar space(extraction of 4 second premolar teeth)after reduction were established based on the cone-beam CT and MRI data.ABAQUS software was used to analyze the stress distribution of various parts of the temporomandibular joint during the interposition of tooth tips. RESULTS AND CONCLUSION:The stress distribution of the condyle,articular disc,and osteoarticular fossa in the model before and after the reduction was basically the same.The stress of the condyle was mainly distributed in the anterior and apical part of the condyle,the stress of the articular disc was mainly distributed in the middle band and lateral part of the articular disc,and the stress of the articular fossa was mainly concentrated in the anterior and apical part of the articular fossa.However,the equivalent stress value of the condyle,articular disc and articular fossa decreased after reduction.After orthodontic reduction extraction,the equivalent stress values of condyle and articular disc in the 1/3 anterior molar space model were smaller than those in the 2/3 anterior molar space model.From the perspective of biomechanics,orthodontic reduction extraction can reduce the stress of the temporomandibular joint and provide a good biomechanical environment.

OBJECTIVETo explore the effect of silence of Pin1 expression on hyperoxia-induced apoptosis in alveolar epithelial cells A549.

METHODSA549 cells were divided into four groups: control, hyperoxia, negative lentivirus and Pin1-shRNA hyperoxia. The hyperoxia group was exposed to a mixture of 95%O2 and 5%CO2 for 10 minutes. Then cells were cultured in a closed environment. After 24 hours, the changes of morphology were observed under an inverted microscope. Cell apoptosis was detected by flow cytometry (FCM). The expression of X-linked inhibitor of apoptosis protein (XIAP) and Caspase-9 were detected by immunohistochemistry. The production of reactive oxygen species (ROS) and cellular mitochondria membrane potential (△Ψm) were determined by fluorescence microscopy.

RESULTSUnder the inverted microscope, the A549 cells grew slowly and the changes in morphology of the cells were most obvious in the hyperoxia and negative lentivirus groups. The changes in morphology of A549 cells were obviously improved in the Pin1-shRNA hyperoxia group. The FCM results showed that the apoptosis rate of A549 cells increased, Caspase-9 expression increased, XIAP expression decreased, mitochondrial ROS production increased and mitochondrial membrane potential decreased in the hyperoxia and negative lentivirus groups compared with the control group (P<0.05). Compared with the hyperoxia and negative lentivirus groups, the apoptosis rate of A549 cells decreased, Caspase-9 expression decreased, XIAP expression increased, mitochondrial ROS production decreased and mitochondrial membrane potential increased in the Pin1-shRNA hyperoxia group (P<0.05), although the levels of the indexes did not reach to those of the control group.

CONCLUSIONSSilencing of Pin1 could suppress hyperoxia-induced apoptosis of A549 cells.

Apoptosis ; Caspase 9 ; genetics ; Humans ; Hyperoxia ; pathology ; Membrane Potential, Mitochondrial ; NIMA-Interacting Peptidylprolyl Isomerase ; Peptidylprolyl Isomerase ; physiology ; Reactive Oxygen Species ; metabolism ; X-Linked Inhibitor of Apoptosis Protein ; genetics