Objective To understand the molecular basis for a potential reaction mechanism and develop novel antibiotics with homology modeling for 3-hydroxy-3-methylglutaryl coenzyme A （HMG-CoA） synthase （HMGS）. Methods The ...Objective To understand the molecular basis for a potential reaction mechanism and develop novel antibiotics with homology modeling for 3-hydroxy-3-methylglutaryl coenzyme A （HMG-CoA） synthase （HMGS）. Methods The genetic engineering technology and the composer module of SYBYL7.0 program were used, while the HMGS three-dimensional structure was analyzed by homology modeling. Results The mvaS gene was cloned from Streptococcus pneumoniae and overexpressed in Escherichia coli from a pET28 vector. The expressed enzyme （about 46 kDa） was purified by affinity chromatography with a specific activity of 3.24 μmol/min/mg. Optimal conditions were pH 9.75 and 10 mmol/L MgCl2 at 37 ℃ The Vmax and Km were 4.69 μmol/min/mg and 213 μmol/L respectively. The 3D model of S.pneumoniae HMGS was established based on structure template of HMGS of Enterococcus faecalis. Conelusion The structure of HMGS will facilitate the structure-based design of alternative drugs to cholesterol-lowering therapies or to novel antibiotics to the Gram-positive cocci, whereas the recombinant HMGS will prove useful for drug development against a different enzyme in the mevalonate pathway.展开更多
In this study cortisol and cyclophosphamide were injected into abdominal cavities of mice to keep them in an immunosuppressive state. Then the pathogen Klebsiella pneumoniae was given to infect the lungs and the exper...In this study cortisol and cyclophosphamide were injected into abdominal cavities of mice to keep them in an immunosuppressive state. Then the pathogen Klebsiella pneumoniae was given to infect the lungs and the experimental modcl of lobular pneumonia in the mice was thus established successfully.The experimental animal model has typical pathologic manifestation and good replication and can be used to to study the effect of drugs.展开更多
Background:The neuropsychiatric disorders due to post-streptococcal autoimmune complications such as Sydenham's chorea(SC)are associated with acute rheumatic fever and rheumatic heart disease(ARF/RHD).An animal mo...Background:The neuropsychiatric disorders due to post-streptococcal autoimmune complications such as Sydenham's chorea(SC)are associated with acute rheumatic fever and rheumatic heart disease(ARF/RHD).An animal model that exhibits char-acteristics of both cardiac and neurobehavioral defects in ARF/RHD would be an important adjunct for future studies.Since age,gender,strain differences,and geno-types impact on the development of autoimmunity,we investigated the behavior of male and female Wistar and Lewis rat strains in two age cohorts(6 weeks and 12 weeks)under normal husbandry conditions and following exposure to group A streptococcus(GAS).Methods:Standard behavioral assessments were performed to determine the impair-ments in fine motor control(food manipulation test),gait and balance(beam walk-ing test),and obsessive-compulsive behavior(grooming and marble burying tests).Furthermore,electrocardiography,histology,and behavioral assessments were per-formed on male and female Lewis rats injected with GAS antigens.Results:For control Lewis rats there were no significant age and gender dependent differences in marble burying,food manipulation,beam walking and grooming be-haviors.In contrast significant age-dependent differences were observed in Wistar rats in all the behavioral tests except for food manipulation.Therefore,Lewis rats were selected for further experiments to determine the effect of GAS.After ex-posure to GAS,Lewis rats demonstrated neurobehavioral abnormalities and cardiac pathology akin to SC and ARF/RHD,respectively.Conclusion:We have characterised a new model that provides longitudinal stability of age-dependent behavior,to simultaneously investigate both neurobehavioral and cardiac abnormalities associated with post-streptococcal complications.展开更多
Objective:To establish extensively drug-resistant Pseudomonas aeruginosa(XDR-PA)infection-induced pneumonia model in rats.Methods:Twenty-four male SD rats were randomly divided into blank group,low bacterial group,med...Objective:To establish extensively drug-resistant Pseudomonas aeruginosa(XDR-PA)infection-induced pneumonia model in rats.Methods:Twenty-four male SD rats were randomly divided into blank group,low bacterial group,medium bacterial group,and high bacterial group.The low,medium and high bacterial groups were given intratracheal instillation of 0.1 mL of bacterial suspension(bacterial concentration in turn is 7.5×10^(9),3×10^(10),6×10^(10)CFU/mL),while the blank group were given the same volume of sterile normal saline.After modeling,the general conditions of rats in each group were observed,including mental state,hair,respiration,activity,eating,weight,and the survival curve was drawn.The pathological characteristics of lung tissue and the infiltration of inflammatory cells were observed.Pathogenic identification of each group was carried out by bacterial culture of lung tissue homogenate.Results:The general state of the blank group was normal,and the rats in other groups showed signs of mental depression,bristling,shortness of breath,even oral and nasal bleeding,decreased food intake and activity,and significant weight loss,and different degrees of death within 48 hours,the difference was statistically significant(P<0.05).Pathological results showed that the alveolar structure of rats in the blank group was complete,and the alveolar space was clear without exudation.The lung tissue of the low and medium bacterial groups showed obvious inflammatory cell infiltration,alveolar structure destruction,alveolar septum thickening,interstitial edema,but the pathological damage of the medium group was more severe,with a mortality rate of up to 50%,and the mortality rate of the low bacterial group was 17%.In the high bacterial group,red blood cells,inflammatory cells and a large amount of fibrin-like exudation can be seen in the alveolar space,which has the pathological characteristics of acute respiratory failure,and the mortality rate is as high as 67%.The results of bacterial culture of lung tissue homogenate showed that the blank group had no bacterial colonies,while PA colony growth can be seen in low,medium and high bacterial groups.Conclusion:9 Intratracheal instillation of low bacterial count(0.1 mL of 7.5×10^(9) CFU/mL)XDR-PA bacterial suspension can successfully construct a rat pneumonia model of XDR-PA infection.展开更多
猪链球菌(Streptococcus suis,SS)是一种重要的人畜共患病原体,猪链球菌2型(Streptococcus suis type 2,SS2)1954年首次在英国分离鉴定,在我国和其他养猪业发达的国家已多次流行,已成为危害我国养猪业和公共卫生安全的一个重要传染病。...猪链球菌(Streptococcus suis,SS)是一种重要的人畜共患病原体,猪链球菌2型(Streptococcus suis type 2,SS2)1954年首次在英国分离鉴定,在我国和其他养猪业发达的国家已多次流行,已成为危害我国养猪业和公共卫生安全的一个重要传染病。本研究用SS2-ZY05719株按10^(9)、10^(8)、10^(6)CFU腹腔注射途径人工感染健康的新西兰兔,3种剂量均可引起发病并死亡,新西兰兔临床症状明显,感染组平均体温升高1℃~2℃。同时分析了SS2在兔体各组织中的分布,结果显示,高剂量感染组出现明显的临床症状且快速死亡,感染剂量与发病程度有正相关性,对各试验组新西兰兔内脏组织进行检测发现,SS2主要集中在心脏、肝脏、脾脏、肺脏、肾脏和脑等组织中,不同组织器官中的细菌载量也存在着一定的差异,本文研究了SS2感染新西兰兔后的临床症状和各组织载菌量,为猪链球菌的防治及致病机理研究提供参考。展开更多
基金supported by the National Natural Science Foundation of China (No. 30771429)Science and Technology Research Project of Ministry of Education (No.106116)+1 种基金Specialized Research Fund for the Doctoral Program of Higher Education (No. 20060511002)the Natural Science Foundation of Hubei Province (No. 2006ABA197)
文摘Objective To understand the molecular basis for a potential reaction mechanism and develop novel antibiotics with homology modeling for 3-hydroxy-3-methylglutaryl coenzyme A （HMG-CoA） synthase （HMGS）. Methods The genetic engineering technology and the composer module of SYBYL7.0 program were used, while the HMGS three-dimensional structure was analyzed by homology modeling. Results The mvaS gene was cloned from Streptococcus pneumoniae and overexpressed in Escherichia coli from a pET28 vector. The expressed enzyme （about 46 kDa） was purified by affinity chromatography with a specific activity of 3.24 μmol/min/mg. Optimal conditions were pH 9.75 and 10 mmol/L MgCl2 at 37 ℃ The Vmax and Km were 4.69 μmol/min/mg and 213 μmol/L respectively. The 3D model of S.pneumoniae HMGS was established based on structure template of HMGS of Enterococcus faecalis. Conelusion The structure of HMGS will facilitate the structure-based design of alternative drugs to cholesterol-lowering therapies or to novel antibiotics to the Gram-positive cocci, whereas the recombinant HMGS will prove useful for drug development against a different enzyme in the mevalonate pathway.
文摘In this study cortisol and cyclophosphamide were injected into abdominal cavities of mice to keep them in an immunosuppressive state. Then the pathogen Klebsiella pneumoniae was given to infect the lungs and the experimental modcl of lobular pneumonia in the mice was thus established successfully.The experimental animal model has typical pathologic manifestation and good replication and can be used to to study the effect of drugs.
基金RAM Rafeek is recipient of International Postgraduate Research Award(IPRA)from University of New England.CM Lobbe and E.Wilkinson are recipients of student scholarship from the Royal College of Pathologists of Australasia(RCPA).
文摘Background:The neuropsychiatric disorders due to post-streptococcal autoimmune complications such as Sydenham's chorea(SC)are associated with acute rheumatic fever and rheumatic heart disease(ARF/RHD).An animal model that exhibits char-acteristics of both cardiac and neurobehavioral defects in ARF/RHD would be an important adjunct for future studies.Since age,gender,strain differences,and geno-types impact on the development of autoimmunity,we investigated the behavior of male and female Wistar and Lewis rat strains in two age cohorts(6 weeks and 12 weeks)under normal husbandry conditions and following exposure to group A streptococcus(GAS).Methods:Standard behavioral assessments were performed to determine the impair-ments in fine motor control(food manipulation test),gait and balance(beam walk-ing test),and obsessive-compulsive behavior(grooming and marble burying tests).Furthermore,electrocardiography,histology,and behavioral assessments were per-formed on male and female Lewis rats injected with GAS antigens.Results:For control Lewis rats there were no significant age and gender dependent differences in marble burying,food manipulation,beam walking and grooming be-haviors.In contrast significant age-dependent differences were observed in Wistar rats in all the behavioral tests except for food manipulation.Therefore,Lewis rats were selected for further experiments to determine the effect of GAS.After ex-posure to GAS,Lewis rats demonstrated neurobehavioral abnormalities and cardiac pathology akin to SC and ARF/RHD,respectively.Conclusion:We have characterised a new model that provides longitudinal stability of age-dependent behavior,to simultaneously investigate both neurobehavioral and cardiac abnormalities associated with post-streptococcal complications.
基金Science and Technology Projects in Key Fields of Traditional Chinese Medicine in Tianjin(No.2021010)Discipline Development Fund of First Teaching Hospital of Tianjin University of Traditional Chinese Medicine(No.XKJJ201734)。
文摘Objective:To establish extensively drug-resistant Pseudomonas aeruginosa(XDR-PA)infection-induced pneumonia model in rats.Methods:Twenty-four male SD rats were randomly divided into blank group,low bacterial group,medium bacterial group,and high bacterial group.The low,medium and high bacterial groups were given intratracheal instillation of 0.1 mL of bacterial suspension(bacterial concentration in turn is 7.5×10^(9),3×10^(10),6×10^(10)CFU/mL),while the blank group were given the same volume of sterile normal saline.After modeling,the general conditions of rats in each group were observed,including mental state,hair,respiration,activity,eating,weight,and the survival curve was drawn.The pathological characteristics of lung tissue and the infiltration of inflammatory cells were observed.Pathogenic identification of each group was carried out by bacterial culture of lung tissue homogenate.Results:The general state of the blank group was normal,and the rats in other groups showed signs of mental depression,bristling,shortness of breath,even oral and nasal bleeding,decreased food intake and activity,and significant weight loss,and different degrees of death within 48 hours,the difference was statistically significant(P<0.05).Pathological results showed that the alveolar structure of rats in the blank group was complete,and the alveolar space was clear without exudation.The lung tissue of the low and medium bacterial groups showed obvious inflammatory cell infiltration,alveolar structure destruction,alveolar septum thickening,interstitial edema,but the pathological damage of the medium group was more severe,with a mortality rate of up to 50%,and the mortality rate of the low bacterial group was 17%.In the high bacterial group,red blood cells,inflammatory cells and a large amount of fibrin-like exudation can be seen in the alveolar space,which has the pathological characteristics of acute respiratory failure,and the mortality rate is as high as 67%.The results of bacterial culture of lung tissue homogenate showed that the blank group had no bacterial colonies,while PA colony growth can be seen in low,medium and high bacterial groups.Conclusion:9 Intratracheal instillation of low bacterial count(0.1 mL of 7.5×10^(9) CFU/mL)XDR-PA bacterial suspension can successfully construct a rat pneumonia model of XDR-PA infection.
文摘猪链球菌(Streptococcus suis,SS)是一种重要的人畜共患病原体,猪链球菌2型(Streptococcus suis type 2,SS2)1954年首次在英国分离鉴定,在我国和其他养猪业发达的国家已多次流行,已成为危害我国养猪业和公共卫生安全的一个重要传染病。本研究用SS2-ZY05719株按10^(9)、10^(8)、10^(6)CFU腹腔注射途径人工感染健康的新西兰兔,3种剂量均可引起发病并死亡,新西兰兔临床症状明显,感染组平均体温升高1℃~2℃。同时分析了SS2在兔体各组织中的分布,结果显示,高剂量感染组出现明显的临床症状且快速死亡,感染剂量与发病程度有正相关性,对各试验组新西兰兔内脏组织进行检测发现,SS2主要集中在心脏、肝脏、脾脏、肺脏、肾脏和脑等组织中,不同组织器官中的细菌载量也存在着一定的差异,本文研究了SS2感染新西兰兔后的临床症状和各组织载菌量,为猪链球菌的防治及致病机理研究提供参考。
