烧伤肠球菌肠源性感染

肠球菌是宿主肠道中正常G~ 球菌,目前已成为医源性感染的重要致病菌。临床上有30％肠球菌感染患者感染源不明,拟肠道来源可能性最大。本文给小鼠肌注灭滴灵3日,造成动物肠系膜淋巴结(MLN)肠球菌的感染率为40％;肌注灭滴灵加口服链霉素,MLN的感染率上升为90％,肝脾内脏中的感染率为83％;联合使用上述抗生素合并25％体表面积烧伤,动物发生致死性肠球菌性肠源性感染,动物诸内脏中肠球菌感染的检出率均高达100％。本研究证明肠球菌感染可以是肠源性的。     

污染细菌对红霉素发酵的影响

木文考查了两种常见污染细菌对红霉素发酵的影响。发现枯草芽孢杆菌污染后迅速引起总糖和还原糖的大量消耗,且在早期就已完全抑制了红霉素的生成;另一种微球菌虽也使发酵过程中的糖耗明显增加,但对红霉素的影响较小,红霉素的合成一直持续到发酵终了。     

霍乱弧菌脂多糖基因在大肠杆菌中的克隆

利用柯斯质粒pHC 79为载体,构建了霍乱弧菌178(埃尔托生物型,小川血清型)染色体基因文库。经血清凝集试验及菌落固相ELISA检测,从基因文库中筛选到13株能够表达霍乱弧菌脂多糖O抗原的阳性克隆。经热酚水法从转化于中提取并纯化的脂多糖能与霍乱弧菌抗血清发生特异性结合。针对重组柯斯质粒PMM—VO 38进行了多种酶切分析,测定其分子量为46kb。     

宁夏、内蒙古的一些早白垩世珠蚌类

宁夏六盘山群上部和内蒙古赛汉塔拉组产出的珠蚌类化石为首次描述,其面貌与邻区相当地层产出的蚌类相似,前人将它们鉴定为Unio。现据它们的壳顶区缺双带构造、前假主齿乳头状并不呈“多”形排列和前闭壳肌痕内具树枝状构造等特征建立Ningxiaconcha gen. nov.。本文还对Pseudelliptio属及其模式种的含义作了补充修订;通过这些珠蚌类化石的对比,宁夏六盘山群和内蒙古赛汉塔拉组可与新疆吐谷鲁群中上部、辽西沙海组和阜新组、山东蒙阴群中上部、浙江寿昌组上段以及苏联、蒙古、德国韦尔登阶进行对比,其时代应归入早白垩世早期。     

Fine needle aspiration diagnosis of Penicillium marneffei infection

A disseminated infection with Penicillium marneffei, a rare human pathogen that may infect both healthy and immunocompromised patients, was diagnosed by fine needle aspiration cytology in a patient infected with the human immunodeficiency virus. The presence of yeast-form organisms with an eccentric or central dot and occasional septate and elongated forms highly suggested the diagnosis, which was confirmed on culture. Establishment of the diagnosis is important because this infection is potentially curable.     

Ni(II) and Ni(I) forms of pentaalkylamide derivatives of cofactor F430 of Methanobacterium thermoautotrophicum.

A series of pentaalkylamide forms of F430 and of its 12,13-diepimer have been generated and characterized. Carbodiimide-assisted N-hydroxysulfosuccinimide activation of all five peripheral carboxylates of the F430 macrocycle allows nucleophilic attack by a number of primary amines (RNH2, R- = CH3-, CH3CH2-, CF3CH2-, CH3(CH2)3-) generating the pentaalkylamide derivatives. The identity of each derivative has been verified by fast-atom bombardment mass spectrometry (FAB-MS). The solubility of these derivatives in aprotic organic solvents varies as the amine alkyl substituent (R-) is changed. Electrochemical measurements have shown that the Ni(II/I) reduction potentials in N,N-dimethylformamide (DMF) are approximately -1 V (Ag/AgCl). Reduction by sodium amalgam in THF generates the Ni(I) form of the F430 diepimer pentabutylamide. The visible and EPR spectra of this Ni(I) species are very similar to the corresponding spectra of Ni(I) F430M (Jaun, B. and Pfaltz, A. (1986) J. Chem. Soc. Chem. Commun. 1327-1329.).     

Neutrophils-induced increase of adenosine triphosphate depletion in rat neonatal cardiac myocytes with impaired energy metabolism.

Isolated, cultured rat neonatal cardiac myocytes were placed in medium supplemented with mitochondrial respiratory inhibitor potassium cyanide which caused a rapid adenosine triphosphate (ATP) depletion. These myocytes with the impaired energy metabolism ("hypoxia-like state") were exposed to unstimulated human neutrophils. Effect of human neutrophils on the myocytes in the "hypoxia-like state" was quantified as a total change in the amount of ATP in cardiac cells. After 5 hours of incubation of neutrophils with the myocytes in the "hypoxia-like state" an additional decrease (of 50 per cent) in ATP content was observed. Since catalase (which destroys hydrogen peroxide) prevented the further decline in ATP level in the myocytes with impaired energy metabolism, it seem that hydrogen peroxide and possibly their products are responsible for this effect. These results suggest that unstimulated human neutrophils after activation by the contact with injured cardiac cells caused further decrease of ATP level in target cells.     

Purification and properties of N5, N10-methylenetetrahydromethanopterin reductase from Methanobacterium thermoautotrophicum (strain Marburg)

The reduction of N5,N10-methylenetrahydromethanopterin (CH2 = H4MPT) to N5-methyltetrahydromethanopterin (CH3-H4MPT) is an intermediate step in methanogenesis from CO2 and H2. The reaction is catalyzed by CH2 = H4MPT reductase. The enzyme from Methanobacterium thermoautotrophicum (strain Marburg) was found to be specific for reduced coenzyme F420 as electron donor; neither NADH or NADPH nor reduced viologen dyes could substitute for the reduced 5-deazaflavin. The reductase was purified over 100-fold to apparent homogeneity. Sodium dodecyl sulfate/polyacrylamide gel electrophoresis revealed only one protein band at the 36-kDa position. The apparent molecular mass of the native enzyme was determined by gel filtration to be in the order of 150 kDa. The purified enzyme was colourless. It did not contain flavin or iron. The ultraviolet visible spectrum was almost identical to that of albumin, suggesting the absence of a chromophoric prosthetic group. Reciprocal plots of the enzyme activity versus the substrate concentration at different constant concentrations of the second substrate yielded straight lines intersecting at one point on the abscissa to the left of the vertical axis. This intersecting pattern is characteristic of a ternary complex catalytic mechanism. The Km for CH2 = H4MPT and for the reduced coenzyme F420 were determined to be 0.3 mM and 3 microM, respectively. Vmax was 6000 mumol.min-1.mg protein-1 (kcat = 3600 s-1). The CH2 = H4MPT reductase was stable in the presence of air; at 4 C less than 10% activity was lost within 24 h.     

Acetaldehyde-collagen adducts in CCl4-induced liver injury in rats

Circulating AC levels as well as antibodies against AC-protein adducts are increased in non-alcoholic liver injury. To identify the adducts, we used rats with CCl4-induced cirrhosis. Liver subcellular fractions were analyzed by immunochemical staining of protein slot blots and of electrophoretically separated proteins, transferred to nitrocellulose, using AC-protein adduct-specific antibodies. One reactive protein of about 200 kD was detected in the liver soluble fraction and in the cytosol of isolated hepatocytes and, to a lesser extent in the liver microsomes of CCl4-treated rats; in control animals, this reactivity was much weaker. The immunopositive AC adduct co-migrated with the beta 1,2 dimer of rat collagen type I; it was sensitive to digestion by a highly purified collagenase and also reacted with anti-rat collagen type I-specific IgG. In addition, comparison of peptides of the CNBr-digested, immunoprecipitated AC adduct with those of rat collagen type I revealed a high degree of similarity. Thus, AC adduct formation occurs in liver injury of non-alcoholic origin, and a target protein appears to be related to collagen type I, most likely the procollagen precursor.     

Role of UV-inducible proteins in repair of various wild-type Escherichia coli cells

3 wild-type strains of E. coli, namely K12 AB2497, B/r WP2 and 15 555-7v proficient in excision and post-replication repair, differ markedly in their UV resistance. To elucidate this difference, the influence was investigated of induction by application of inducing fluence (IF) before lethal fluence (LF) on repair processes after LF. In cells distinguished by low UV resistance (E. coli 15 555-7; E. coli B/r WP2), dimer excision was less complete in cultures irradiated with IF + LF than in cultures irradiated with LF only. The highly resistant E. coli K12 AB2497 performed complete excision both after IF + LF or after LF alone. All 3 types of cell survived better after IF + LF than after LF only. Because, in most strains so far investigated, the application of IF reduced dimer excision and increased survival, dimer excision per se does not appear important for survival.We conclude that the rate and completeness of dimer excision can serve as a measure of efficiency of the excision system whose action is necessary for repair of another lesion. Cells of all investigated strains could not resume DNA replication and died progressively when irradiated with LF and post-incubated with chloramphenicol (LF CAP⁺). Thus, it appears that inducible proteins are necessary for repair in all wild-type E. coli cells give with potentially lethal doses of UV irradiation.