The isolation purification, iodination and identification of a-Bungarotoxin(a-BTX)were recorded.Purified a-BTX was prepared from the venom of Hunan Bu-ngarus multicinctus (Blyth) by CM-Sephadex C~50 ionexchange chromatography and Sephadex G~25 chromatography.The homogeneous a-BTX was obtained by rechromatography of purified ct-BTX (fraction 3) on a CM-Cellulose CM-32, and was labelled with 1251 by chloramine-T method.The 1251-?-BTX was then separated from Na125I and purified by Sephadex G-25 column.The results yield a specific activity of 90~100 Ci/mM.40~50% labelling.40~60% recovery of protein and less than 3 % contamination with free iodine in 125I-?-BTX.The purified a-BTX was identified by determining its N-terminal amino acid, amino acid composition, isoelectric and polyacrylamide gel electrophoresis.Biological activity of the ?-BTX was determined by its toxicity to mice, its neuromuscular blocking action and binding to acetylcholine receptors at the motor entplate of the rat diaphragm.

The present study describes the effects of carbamate anti-cholinesterase agents and other drugs on the binding sites and on the turnover of nicotinic acetylcholine receptors (N-AChR). The direct binding studies with 125I-?-Bungarotoxin have shown that the neostigmine, prostigmine, pyridostigmine, and ambenonium specifically blockada the N-AChR binding sites, but physostigmine has no directly effect on the N-AChR binding sites.Small dose of ambenomine increases degradation rate of surface N-AChR and it decreases the rate of new N-AChR incorporation into membrane. The bindings of sodium phenobabital to N-AChR sites are very similar to those of d-tubocurarine. The parathion(E605)has no direct bindes to N-AChR sites. The density of extrajunc-tional N-AChR sites is increased and the RBI is 1.46.

The present study reports direct effects of allosteric snake neurotoxin (MN-81) on the nicotinic acetylcholine receptor (N-AChR) and on the transmission of nuro-muscular junction. when one dose of MN-81 with 50 ?g/kg body weight was injected into the mice, the number of N-AChR binding sites was not changed. when one dose of MN-81 with 250 ng/kg body weight was injected, 23 per cent of total N-AChR were occupied by MN-81 molecules. But when repeated injection of MN-81 was carried out N-AChR binding sites were increased by about 34 percent. Assay of phrenic nerve-diaphragm showed that the low close of MN-81 increased contractile amplitude of isolated rat diaphragm and rabbit diaphragm in situ, while an increase in the concentration of MN-81 (10-4g/ml) led to blockade of nuromus-cular transmission.

The highly specific ligand of the N-acetylcholine receptor (N-AChR) was used to determine the effect of scman, sarin and VX on N-AChR of the diaphragm, and extensor digitorum longus muscle of the mouse and rat The effects of the three anticholinesterase agents on N-AChR were different Sarin didn't directly act on N-AChR and cause a change in the number of N-AChR VX decreased the binding site of the receptor through directly binding N-AChR The ID50 was 0.054 mg/kg mouse. Soman increased the binding sites, e.g. 1-1.5 LD50 soman increased the N-AChR of mouse diaphragm for 25% of the control. The increase in N-AChR was up to a highest peak 0.5 h after poisoning and continued for 96 h. The receptor number was still 22% higher than that of the control on the fourth day after soman poisoning in the rat Soman mainly increased the number of extrasynaptic N-AChR, leading to the enhancement of sensitivity of cholinergic effector to ACh. This simulates the sensibilization resulting from denervation. These findings are of significance in probing the receptor mechanisms and treatment of the soman poisoning.

The effects of carbamates and soman on the metabolism of nicotinic acetylcholine receptors (N-AChR) in cultured skeletal muscle cells were studied by 125I-a-bungarotoxin (125I-a-BTX), a specific marker. It was indicated that N~AChR degradation process was inhibited and the incorperation rate of IshAChR and the number of N~AChR in the surface of the cell membrane were increased 4h after prertreatment of high concentrations of carbamates. The number of N-AChR was also increased after pre-treatment of low concentrations of soman, whose effects on N-AChR metabolism were similar to those of high concentrations of carbamates. The incorperation rate of N-AChR was observed by inhibiting the protein synthesis with puromysin, suggesting that soman may increase the number of N-AChR by increasing the incorperation of N-AChR instead of increasing the synthesis of N-AChR.

Autoradiography of nicotinic acetylcholine receptors (N-AChR) with the application of histochemical staining location of cholinesterase was used to observe the effect of soman on junctional and extrajunctional N-AChR. Testing with the diaphragms and extensor digitorum longus muscles of mice and rats, we found that soman mainly increased the number of extrajunctional N-AChR. It did pot alter the number of junctional N-AChR significantly, nor did it have any pronounced effects on the glycoprotein property and isoelectric point (pI) of junctional and extrajunctional N-AChR. The change of extrajunctional N-AChR number caused by soman is similar to the phenomenon of increased extrajunctional N-AChR number and sensitivity resulting from denervation, but the mechanism of action is different from the latter. The increase of N-AChR number is one of the important characteristics of soman poisoning which make it different from other nerve agents. To maintain the metabolic balance of N-AChR may be an important new approach to the treatment of soman poisoning.

ObjectiveTo investigate the association of hypertensive target organ damage with abnormal ankle brachial index (ABI) in high-risk hypertensive patients.MethodsDuring December 2008 to May 2009,a cross-sectional study was conducted to investigated the prevalence of abnormal ABI (ABI ＜ 0.90) in 2674 community-dwelling,hypertensive patients,who aged ＞ 40 years,without coronary heart disease,stroke/transient ischemic attack or known arteriosclerosis,from 18 centers in China. Data were acquired through history,physical examination,laboratory and other diagnostic tests.ResultsThere were 2615 subjects eligible for the full analysis set. The high-risk hypertensive patients with arterial wall thickening,arterial wall thickening and slightly elevated serum creatinine had a higher prevalence of abnormal ABI than their counterparts respectively ( P ＜ 0.05 ). Compared with the normal group,the abnormal ABI group had a higher serum creatinine level on average (P ＜ 0.01 ).After adjustment for certain factors including investigation center,demographic factors,cardiovascular disease (CVD) risk and CVD risk factors using an unconditional logistic regression model,arterial wall thickening ( OR 2.416,95％ CI 1.395-4.183,P =0.0016 ) and slightly elevated serum creatinine ( OR 3.377,95％ CI 1.267-8.997,P =0.0149) were positively associated with abnormal ABI. However,arterial wall thickening (OR 0.988,95％ CI 0.576-1.695,P=0.9664) and microalbuminuria (OR 1.389,95％ CI0.685-2.817,P=0.3621)were irrelevant to abnormal ABI.Conclusions So far as a high-risk hypertensive patient is concerned,there are significant statistical correlations between arterial wall thickening and/or slightly elevated serum creatinine and an abnormal ABI,but no significant statistical correlations between arterial wall thickening or microalbuminuria and an abnormal ABI is observed.

ObjectiveTo investigate the specific anti-SARS-CoV-2 antibody in adults and above after initial vaccination with inactivated COVID-19 vaccine， and determine the influencing factors. MethodsIn this study， residents aged 18 and above who had completed two doses of inactivated COVID-19 vaccine in Deqing County， Huzhou City， Zhejiang Province were included. Information such as gender， age， type of vaccine and vaccination time were collected， and serum specimens were sampled. Anti-SARS-CoV-2 receptor binding domain （RBD） antibody was quantitatively examined by enzyma-linked immunosorbent assay （ELISA） and influencing factors were determined. ResultsThe median concentration of anti-SARS-CoV-2 IgG antibody in the residents vaccinated with an inactivated booster vaccine was higher than that in those vaccinated with only two doses of COVID-19 vaccine or single dose （P<0.05）. The median concentration of IgG antibody in males was 9.73 （4.01‒23.70） RU‧mL^-1， lower than 17.76 （7.07‒49.23） RU‧mL^-1 in females （P<0.05）. The median concentration in the residents vaccinated with BBIBP-CorV （Sinopharm） was 6.53 （0.97‒13.69） RU‧mL^-1， which was lower than that in those vaccinated with CoronaVac （Sinovac） that was 17.29 （8.54‒43.73） RU‧mL^-1 （P<0.05）. The median concentration in those with BBIBP-CorV was also lower than 12 （5.45‒40.06） RU‧mL^-1 in those with heterologous booster vaccine （P<0.05）. The median concentration was 9.73 （3.83‒23.63） RU‧mL^-1 in the residents with an interval of more than 6 months from the second dose， which was lower than 14.66 （6.36‒35.98） RU‧mL^-1 in those with an interval of 3‒6 months （P<0.05）. Moreover， immune effect was better in females （χ²=16.464， P<0.05）， 18‒45 years（χ²=7.158， P<0.05）， and those vaccinated with CornaVac （χ²=49.637， P<0.05）， while decreased in those with an interval of more than 6 months from the second dose （χ²=8.447， P<0.05）. ConclusionGender， age， and type of vaccine may affect the effect of immunization. The COVID-19 vaccination shows an acceptable immunogenicity in adults； however， it declines in 6 months after vaccination. It warrants strengthening the booster vaccination to maintain the immune response.

ObjectiveTo determine the serum antibody level and risk factors in the adolescent population in a county in Zhejiang Province， following the immunization with inactivated COVID-19 vaccine， and to construct a prediction model for antibody concentration. MethodsWe conducted the study in a county in Zhejiang Province， employing a stratified cluster random sampling strategy in school children who had received the inactivated COVID-19 vaccine. Data on gender， age， type of vaccine， and time of vaccination was collected. Serum samples were also collected to test for anti-S and N IgG antibody against the SARS-CoV-2 by using chemiluminescent immunoassay （CLIA）. Risk factors were determined to construct a prediction model for antibody concentration. ResultsThe IgG antibody concentration was significantly higher in girls， those who received two doses， and those who had simply received the KX vaccine . It decreased with age and time interval between the sampling and last vaccination. The prediction model constructed by random forest regression in the study had a better model fit and predictive ability than that by the multivariable linear stepwise regression. ConclusionGender， age， vaccination dose， type of vaccine， and time of vaccination are associated with vaccination effectiveness of inactivated COVID-19 vaccines in adolescents. Prediction model could predict the antibody level in the vaccinated population， which can provide a new tool for better evaluation of vaccination effectiveness against emerging infectious diseases in future.

ObjectiveAntibiotic resistance genes （ARGs） have received wide attention all over the world. The purpose of this study was to explore the bacterial community structure， the types and levels of antibiotic resistance genes in a water body in east China， and to compare and analyze the characteristics of microbial species distribution and antibiotic resistance gene distribution in various water environments. MethodsA total of 10 households in Haimen City， Jiangsu Province were selected and their surrounding water environment samples were collected. 21 water samples including river water （4）， Mingou water （9） and well water （8） were collected for metagenomics sequencing， assembled with MetaWRAP， annotated with CARD database， and analyzed with R software. ResultsIn various water bodies， the dominant bacteria phyla was Proteobacteria， the dominant bacteria genera were Deuterostomia， Pseudomonas， Flavobacteriales and Streptomycetaceae. The ARGs annotated were mainly composed of quinolones， aminoglycosides， macrolides and beta-lactams antibiotic resistance genes. The top four relative abundance of resistance genes were macB， RanA， evgS and TxR， The average absolute abundance and expression of resistance genes in well water and Mingou water were higher than those in river water. ConclusionMultiple ARGs are detected to varying degrees in well water， river water， and Mingou water bodies， and the expression of resistance genes in well water and Mingou water bodies is higher than that in river water bodies， possibly due to human production and living activities.