甲基强的松龙对大鼠颅脑损伤后一氧化氮合成酶活性和内皮素的影响

目的观察甲基强的松龙对大鼠颅脑损伤后血脑组织中NOS和内皮素含量的影响,并探讨其作用机制.方法将45只SD大鼠随机分为3组,采用骨窗形成后硬膜外打击法造成鼠脑挫裂伤模型,正常组5只,麻醉后,只行开颅手术,不作头颅打击;治疗组大鼠致伤后即刻腹腔内注射30mg/kg甲基强的松龙,对照组则即刻腹腔内注射30mg/kg生理盐水.对照组和治疗组大鼠分别在伤后1h、6h、12h、24h时间点断头取脑,对大鼠脑外伤后脑组织中NOS和内皮素含量进行检测.结果①大鼠脑皮质中的NOS活性在伤后1h后较对照组升高显著(p<0.01),6h开始下降,12～24h降至基础水平.甲基强的松龙治疗组在伤后1h、6hNOS活性较损伤组明显降低(p<0.01,p<0.05).②大鼠脑皮质中的内皮素在伤后1～24h后较对照组升高显著(p<0.01).甲基强的松龙治疗组在伤后1～24h内皮素较损伤组明显降低(p<0.05).结论颅脑损伤后,受损脑组织中NOS和内皮素升高,甲基强的松龙可通过抑制损伤后NOS和内皮素,起到保护创伤神经元的作用.     

甲基强的松龙对大鼠颅脑损伤后一氧化氮合成酶活性和内皮素的影响

目的观察甲基强的松龙对大鼠颅脑损伤后血脑组织中NOS和内皮素含量的影响,并探讨其作用机制. 方法将45只SD大鼠随机分为3组,采用骨窗形成后硬膜外打击法造成鼠脑挫裂伤模型,正常组5只,麻醉后,只行开颅手术,不作头颅打击;治疗组大鼠致伤后即刻腹腔内注射30mg/kg甲基强的松龙,对照组则即刻腹腔内注射30mg/kg生理盐水.对照组和治疗组大鼠分别在伤后1h、6h、12h、24h时间点断头取脑,对大鼠脑外伤后脑组织中NOS和内皮素含量进行检测.结果①大鼠脑皮质中的NOS活性在伤后1h后较对照组升高显著(p<0.01),6h开始下降,12～24h降至基础水平.甲基强的松龙治疗组在伤后1h、6h NOS活性较损伤组明显降低(p<0.01,p<0.05).②大鼠脑皮质中的内皮素在伤后1～24h后较对照组升高显著(p<0.01).甲基强的松龙治疗组在伤后1～24h内皮素较损伤组明显降低(p<0.05).结论颅脑损伤后,受损脑组织中NOS和内皮素升高,甲基强的松龙可通过抑制损伤后NOS和内皮素,起到保护创伤神经元的作用.     

BOOK REVIEW: Polyurethanes in Biomedical Applications, by N. Lamba, K. Woodhouse, and S. Cooper

PAC00: 0130Vv, 8768+z     

Contributions to the study of Salmonella: II. Protein determinants shared by S. typhi, S. enteritidis and S. typhimurium

The antigenic relationship between S. typhi and S. enteritidis, that at present are known to share only the polysaccharide factors 9 and 12, has been investigated with a view to confirming the existence of common protein O specificity.

A serum to S. enteritidis absorbed with the polysaccharide of S. typhi O-901 and a serum to S. enteritidis in which the polysaccharide antibodies were present in extremely small amounts (undetectable in agar diffusion tests) precipitated with extracts containing proteins of S. typhi.

Additional evidence of the existence of common protein O factors was obtained by precipitin tests in agar in which sera to proteins from S. typhi reacted with proteins of S. enteritidis and S. typhimurium (whose H determinants differ from one another); the precipitations of heterologous proteins in agar-gel varied in intensity according to the antibody content of the antiprotein sera tested and to the proportion of O determinants of the respective protein. Heterologous precipitin reactions of the sera to S. enteritidis with antigens from S. typhi were stronger than those with the homologous antigen, whereas the antigens from S. enteritidis were but weakly precipitated by the sera to S. typhi.

This appears to indicate an intrinsically higher antigenic potency of S. typhi, compared with S. enteritidis.

     

Schistosoma japonicum,S. mansoni,S. haematobium,S. intercalatum,and S. rodhaini: cysteine-class cathepsin activities in the vomitus of adult worms

 Vomitus from adults of five Schistosoma species was screened for biochemical homologues of the mammalian cysteine proteinases cathepsins B, H, and L. Bovine cathepsin B and rat cathepsin L served as references. Using the substrate Arg-NMec, a schistosome cathepsin H-like activity was never detected. All species degraded the cathepsin B substrate Z-Arg-Arg-NMec, but distinct species differences were observed with respect to pH optima and buffer preferences. The cathepsin B and L substrate Z-Phe-Arg-NMec was similarly degraded by all species, and activity was abolished by the cysteine proteinase inhibitor E-64. Preferences by vomitus proteinase activities for Z-Phe-Arg-NMec over Z-Arg-Arg-NMec were similar to or higher than those found for bovine cathepsin B but well below those observed for rat cathepsin L; also, the preferential cathepsin L inhibitor Z-Phe-PheCHN₂ only partially inhibited proteinolytic activity. The results suggest the possible presence in vomitus of a minor cathepsin L-like activity and demonstrate a major cathepsin B-like activity that is biochemically variable between schistosome species. Received: 1 April 1996 / Accepted: 19 June 1996     

Schistosoma haematobium,S. intercalatum,S. japonicum,S. mansoni,and S. rodhaini in mice: relationship between patterns of lung migration by schistosomula and perfusion recovery of adult worms

The development of five schistosome species was compared in mice by the recovery of schistosomula from chopped lung tissue and of adult worms by portal perfusion. Three developmental patterns appeared. (1) Schistosoma japonicum was unique in showing an early establishment of schistosomula in and a rapid departure from the lungs together with the highest worm recovery; (2) S. haematobium contrasted by establishing later and persisting in the lungs for at least 2 weeks while yielding the lowest adult worm recovery; and (3) S. intercalatum, S. mansoni, and S. rodhaini had an intermediate pattern – they resided in the lungs for several days, then disappeared and produced intermediate numbers of adults. Lung petechiae, known to accompany the migration of S. japonicum, were never detected after infection with the other species. We speculate that the three migration patterns of schistosomes are related to the size of the relative spectra of naturally infected definitive hosts. Received: 31 August 1997 / Accepted: 15 October 1997     

Natural antibiotic susceptibility of Klebsiella pneumoniae, K. oxytoca, K. planticola, K. ornithinolytica and K. terrigena strains

The natural susceptibility of 221 Klebsiella strains to 71 antibiotics was examined. The strains were isolated from clinical specimens and the environment, and belonged to K. pneumoniae subsp. pneumoniae (n = 40), K. pneumoniae subsp. ozaenae (37), K. pneumoniae subsp. rhinoscleromatis (10), K. oxytoca (44), K. planticola (40), K. ornithinolytica (25) and K. terrigena (25). MIC values were determined by a microdilution procedure in IsoSensitest broth according to the German standard (DIN). All Klebsiella spp. were naturally resistant or intermediate to amoxicillin, ticarcillin and to antibiotics to which other Enterobacteriaceae are also intrinsically resistant. Klebsiella spp. were naturally sensitive or intermediate to several penicillins, all tested cephalosporins, aminoglycosides, quinolones, tetracyclines, trimethoprim, cotrimoxazole, chloramphenicol and nitrofurantoin. K. pneumoniae subsp. ozaenae and subsp. rhinoscleromatis strains were generally more susceptible to antibiotics than strains of other Klebsiella taxa. K pneumoniae subsp. rhinoscleromatis was the most susceptible taxon, being highly susceptible to cefuroxime, anti-folates and naturally intermediate to erythromycin and clarithromycin. K. pneumoniae subsp. ozaenae was most susceptible to glycopeptides. K. oxytoca and K. terrigena strains were least susceptible to cefazoline, cefoperazone and fosfomycin, respectively. The results of the present study describe a database of the natural antimicrobial susceptibility of Klebsiella spp., which can be used for the validation of antibiotic susceptibility results of these bacteria. MIC patterns to beta-lactams indicate the expression of chromosomally encoded class A gamma-lactamases in all the species, including the subspecies of K. pneumoniae. Similar natural susceptibility patterns of K. planticola and K. ornithinolytica to all tested antibiotics support the status of K. ornithinolytica as a biovar of K. planticola.