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61.
Charles E. Stager Dr. James R. Davis Mario N. Saccomani Corpus O. Ortigoza Reuben D. Wende James W. Raleigh 《Current microbiology》1988,17(5):243-247
Two-hundred and fifteen isolates ofMycobacterium tuberculosis were evaluated with the BACTEC 460 radiometric method for susceptibility to isoniazid, rifampin, ethambutol, and streptomycin (SM); a revised protocol for inoculum preparation was used. Fresh clinical isolates were subcultured into 7H9 broth and then photometrically adjusted to the equivalent of a 0.5 McFarland standard, one-half the recommended inoculum density. This method produced an overall 98.3% correlation with a conventional agar method. The sensitivity of this procedure was good for all drugs tested except for the lowest concentration of SM (2 g/ml). Specificity was excellent for all drugs tested. After repeat testing, only four discrepancies were found, yielding a 99.8% correlation between the two systems. The time required for susceptibility tests averaged 4.6 days. This method for inoculum preparation effectively minimized the number of susceptibility tests exceeding the threshold value before the fourth day of incubation. This allowed for definite trends of the growth index values to become established before interpretation of results. 相似文献
62.
Abstract Low concentrations (e.g. 2 × 10−6 M) of an imidazole derivative anti-fungal agent, miconazole, were lethal for the Gram-negative, facultative aerobic pathogen Neisseria gonorrhoeae grown either alone or in mixed culture with the yeast Candida albicans . Electron microscopic observation of Neisseria cells exposed to miconazole showed the presence of blebs in the outer wall and areas of separation between the wall and the cytoplasmic membrane. Sodium dodecyl sulphate-polyacrylamide gel electrophoresis (SDS-PAGE) of cell lysates did not reveal differences in major outer membrane proteins between the treated and the untreated cells of any one strain. Imidazole derivatives are frequently used in the treatment of candidiasis. Our in vitro results show that low concentrations of one of them, miconazole, can be bactericidal for N. gonorrhoeae , a bacterium that can colonise sites of the human body where Candida is often found. 相似文献
63.
John M. Fairbrother Réal Lallier Linda Leblanc Mario Jacques Serge Larivière 《FEMS microbiology letters》1988,56(3):247-252
Abstract The production of fimbrial antigen F165 by Escherichia coli strains was found to be dependent on the composition of the culture medium and was repressed in the presence of alanine or high levels of glucose, in anaerobic conditions or at growth temperatures of lower than 37°C. Optimal F165 production was found on a minimal medium containing 1% (w/v) casamino acids (MD-1). F165 antigen was isolated from bacteria by mechanical shearing, precipitated with ammonium sulfate, and purified by deoxycholate treatment and gel filtration on Superose 12. The purified fimbriae retained their native morphology as observed by electron microscopy and consisted of two separate protein subunits with apparent molecular weights of 17 500 and 19 000 on sodium dodecyl sulfate-polyacrylamide gels. 相似文献
64.
65.
Summary A systematic study was made of the action of 4-acetamido-4-isothiocyanostilbene-2,2-disulfonic acid (SITS) and 4,4-diisothiocyanostilbene-2,2-disulfonic acid (DIDS) on active Ca2+ transport of human erythrocytes. Pumping activity was estimated in inside-out vesicles (IOV's) by means of Ca2+-selective electrodes or use of tracer45Ca2+. The stilbenes exhibited an approximately equal inhibitory potency and their action could be overcome by carbonyl cyanidep-trifluoromethoxyphenylhydrazone (FCCP) at low but not at high stilbene concentrations. In the absence of DIDS. Ca2+ transport was not affected upon addition of valinomycin, but it was appreciably reduced when vesicles were preincubated with low DIDS concentrations. Such an effect was strictly dependent on the external K+ concentration and it was abolished when valinomycin was added together with FCCP. Similar results were obtained using IOV's prepared from intact cells which had been previously exposed to the stilbene. The findings clearly demonstrate the presence in human red cells of a partially electrogenic Ca2+ pump, exchanging one Ca2+ ion for one proton. 相似文献
66.
Dusica Maysinger Pedro Piccardo Michel Goiny A.Claudio Cuello 《Neurochemistry international》1992,21(4)
In this study, microdialysis was used to investigate functional recovery of central cholinergic neurons in the forebrain of rats with cortical devascularizing lesions. Mature male rats were unilaterally lesioned by disruption of the pia arachnoid vessels and genetically modified fibroblasts secreting nerve growth factor (NGF) were placed at the site of the lesion. One month following surgery, microdialysis probes were installed in the remaining cortex and were perfused with artificial cerebrospinal fluid (csf) containing neostigmine (5 nM) and/or KCl (100 mM). The basal (non-stimulated) release of acetylcholine (ACh) in the cortex was similar in all experimental groups, whereas KCl stimulated release of ACh was significantly augmented (P < 0.05) in the ipsilateral remaining cortex in lesioned animals that have been implanted with fibroblasts secreting NGF. These results suggest that NGF secreted by genetically engineered fibroblasts modulates neuroplasticity in the adult mammalian CNS and may favour recovery of cortical function following injury. 相似文献
67.
Mario Penna Robert R. Capranica Jane Somers 《Journal of comparative physiology. A, Neuroethology, sensory, neural, and behavioral physiology》1992,170(1):73-82
Summary Twenty four castrated male, 6 intact male, and 11 intact female Hyla cinerea were injected subcutaneously with 25 g arginine-vasotocin (AVT) and induced to call 1 h later in response to the playback of a conspecific mating call. Eighteen castrated males and 8 intact females were implanted 5 mg androgen pellets for 3 weeks prior to the neuropeptide injection. Among castrated males, 6/9 testosterone (T) implanted, 4/9 dihydrotestosterone (DHT) implanted and 2/6 non implanted individuals produced calls after being administered AVT. 5/6 intact non implanted males and 6/8 T intact implanted females also called, and 3 intact non implanted females remained silent after the injection. Evoked calls had a mid-frequency spectral peak at about 1900 Hz which is absent in field-recorded mating calls of this species. Calls of implanted females and castrated non implanted males were shorter than those of castrated implanted and intact non implanted males. Audiograms measured before hormone implants showed dips of enhanced sensitivity at about 0.5, 0.9 and 3.0 kHz in males and females. After AVT injection, thresholds at frequencies within the 0.7–1.5 kHz range were increased in castrated males. Such reduction in sensitivity points to an inhibition of the auditory system during hormone induced vocal activation.Abbreviations
AVT
arginine-vasotocin
-
DHT
dihydrotestosterone
-
T
testosterone
-
TS
torus semicircularis 相似文献
68.
69.
Ethanol alters almost all membrane functions, but it behaves essentially like a benzodiazepine-type GABAergic agonist. The mechanism by which ethanol affects the GABA/benzodiazepine complex is not clear. We studied the possible changes in [3H]flunitrazepam binding induced by chronic ethanol treatment, using light microscopic autoradiography, to try to elucidate the controversy underlying this topic. This technique allows us to measure densities of benzodiazepine receptors in different anatomical brain areas—visual cortex and hippocampus—which seem to constitute the anatomical support for the behavioral and physiological responses affected by ethanol. Autoradiographic studies on the visual cortex and hippocampus from rats chronically treated with ethanol do not show statistically significant differences in the binding of, [3H]flunitrazepam with respect to control animals. Furthermore, we did not find either rostro-caudal or medio-lateral differences, in benzodiazepine receptor densities in each layer of the visual cortex. 相似文献
70.
Gianluigi Discalzi Francesco Furno Luigi Gagliardi Mario Ambroso Jacqueline Mavro 《Aerobiologia》1992,8(1):62-68
Summary The purpose of this study is to verify and assess, in working conditions, the respiratory exposure to PPD of hairdressing parlour personnel. Several air samples collected in a hairdressing parlour during the time required for 8 applications of dyeing products containing PPD 2.52% have been analyzed. Tests are also carried out by extracting air immediately above the bowls containing the dyeing products, both at room temperature and at 37°C. PPD was assessed by means of HPLC. Only air sampled directly on bowls at 37°C has shown a level of 1 g, corresponding to an environmental release of PPD equivalent to 8 applications of dyeing products. On the basis of these experimental data, the PPD concentration in the air according to the parlour volume and to the supposed air exchanges has been calculated. Our results show a substantial insignificance of the concentration of PPD released in the environmental air during normal operations of hair dyeing: authors are of the opinion that hairdressers can't be truly considered as a PPD-asthmatic risk category like other workers exposed to PPD dust dispersed in the air of their working environment. 相似文献