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51.
J Regnstr?m G Walldius S Nilsson LS Elinder J Johansson J M?lgaard I Holme AG Olsson J Nilsson 《Canadian Metallurgical Quarterly》1996,125(2):217-229
Our knowledge of the traits possessed by extraintestinal isolates of Escherichia coli, necessary for growth and survival in urine, is limited. To identify such determinants, transposon (TnphoA'1,4) mutant libraries of a clinical isolate (CP9) were generated and screened for derivatives exhibiting decreased growth in urine in vitro, and for mutants with active lacZ fusions that were induced in urine relative to laboratory medium. Using this approach we identified two genes, guaA (CPA24) and argC (CPI-1), which were previously unrecognized as being important for growth in human urine. Unexpectedly, not only does CPA24 (guaA) not grow in human urine in vitro, but it is sensitive to its effects, undergoing a 2-3 log loss of viability over 6 h. By contrast, CPA24 neither grows nor is killed in M9 minimal medium and artificial urine. Therefore, we postulate that lack of guanine or its derivatives in urine, and the inability of CPA24 to synthesize these compounds de novo, prevents CPA24 from synthesizing other guanine (or derivatives)-dependent products that are critical for growth and survival in urine. Although it seems logical that decreased growth in urine in vitro should correlate with diminished urovirulence, this concept was tested by challenging mice with CPA24 in vivo in a mouse model of urinary tract infection (UTI). Indeed, CPA24 was found to be significantly less virulent compared with its wild-type parent CP9. CPI-1(argC) was identified because of the significant induction of its argC::lacZ fusion in urine. Subsequent testing in urine demonstrated that its growth was significantly diminished in all urine samples tested (four females, three males). Polyamine synthesis is dependent upon, in part, the arginine biosynthetic pathway. Therefore, we tested whether the induction of argC in urine and/or the decreased growth of CPI-1 was a result of low levels of polyamines or arginine in urine. The results suggest that low levels of arginine, but not polyamines, in human urine are responsible. When tested in vivo in the mouse model of UTI, CPI-1 was also found to be significantly less virulent than CP9. In summary, we have established that guaA and argC are the first genes, which we are aware of, that have been shown to contribute to the growth of E. coli in urine in vitro and both have diminished urovirulence in vivo. These results support the concept that urine can be used in vitro as a screening tool to identify urovirulence traits. 相似文献
52.
BK Madsen H Egeblad R Videbaek LS Mortensen S H?jberg C S?rum TM Melchior JF Hansen 《Canadian Metallurgical Quarterly》1996,158(38):5296-5299
The aim of the study was to evaluate the prognostic significance of clinical and echocardiographic data in patients referred for echocardiography in a retrospective analysis. Four hundred and fifty-six patients from a district hospital were studied. Survival after three years was 64%. Multivariate analysis identified five factors with independent prognostic information (relative risks of death are shown in brackets): left ventricular wall motion index (WMI) < or = 1.2 by echocardiography (2.5), status as in-patient (2.1), age > 65 years (1.7), clinical heart failure (1.9) and atrial fibrillation (1.5). When information on age, hospitalisation status, heart failure and heart rhythm had already been entered in the Cox model, echocardiographic results such as decreased WMI and dilated right ventricle still gave further prognostic information. We conclude that among conventional clinical and echocardiographic data WMI was the strongest predictor of long-term survival, and, despite prior knowledge of major clinical features, echocardiography provided further prognostic information. 相似文献
53.
54.
R Carrizo ME Sosa LS Favier F Penna E Guerreiro OS Giordano CE Tonn 《Canadian Metallurgical Quarterly》1998,61(10):1209-1211
Growth-inhibitory activities of selected natural benzofurans (4-9), trans-cinnamic acid derivatives (10-13), chromene compounds (14 and 16), and some semisynthetic derivatives were determined in last instar larvae of Tenebrio molitor via topical administration in Me2CO. The most inhibitory of the tested compounds were 3-gamma, gamma-dimethylallyl-p-coumaric acid (10) and the benzofuran derivative 12-(p-cumaroyloxy)-tremetone (5), the former compound acting on the pupae and the latter on the last instar larvae. Several developmental deficiencies were observed, and some structure-activity relationships are discussed. 相似文献
55.
Several endogenous oscillators determine circadian rhythms. One, light-entrained, is in the suprachiasmatic nuclei (SCN), the others, food-entrained, are in unknown sites. To determine how the hypothalamic ventromedial nuclei (VMN) and feeding affect rhythms, we compared nocturnally active rats fed either ad libitum or for 2 hr/d during light [restricted feeding (RF)] and either with or without colchicine-induced disruption of VMN. We measured rhythms in temperature, locomotor activity, feeding, drinking, corticosterone, and the numbers of cells expressing c-Fos in light/dark in hypothalamic nuclei, the suprachiasmatic nuclei, and two major SCN targets, the subparaventricular zone (sPVNz) and paraventricular thalamus (pvTHAL). c-Fos cells were always light > dark in SCN, whereas the VMN and sPVNz lacked light/dark differences except after RF and RF plus VMN disruption, respectively. Controls fed ad libitum had high-amplitude rhythms and, generally, c-Fos cells dark > light. In RF controls, a c-Fos pattern dark > light occurred in VMN; generally, c-Fos cell numbers increased elsewhere maintaining dark > light. By contrast, levels of corticosterone peaked before food. In rats fed ad libitum, VMN with colchicine markedly reduced rhythm amplitudes, not phase. c-Fos patterns were abolished except in pvTHAL and SCN. In RF, VMN disruption blocked corticosterone and light/dark c-Fos patterns in all nuclei but produced a pattern in the sPVNz like SCN. We conclude that VMN amplify rhythmic output from the SCN, and the RF-induced rhythm in VMN enhances c-Fos activity driven by the SCN. The VMN may contain a food-entrained oscillator, and the sPVNz may integrate output from several oscillators. 相似文献
56.
Two cases of suprascapular neuropathy after excision of the distal clavicle are reported. Both patients were treated successfully with neurolysis of the suprascapular nerve starting at the upper trunk of the brachial plexus. Anatomic dissections revealed that the suprascapular nerve is quite close (<1.4 cm) to the posterior aspect of the distal clavicle, within 2 to 3 cm of the acromioclavicular joint. To avoid the complication of suprascapular neuropathy that could be associated with this close relationship, it is recommended that no more than 1 cm of the distal clavicle be removed posteriorly. It is also recommended that minimal periosteal elevation should be performed on the posteroinferior border of the distal clavicle. 相似文献
57.
58.
LS Buchanan 《Canadian Metallurgical Quarterly》1996,15(2):42, 44-6, 48-9 passim
59.
To understand the role of the spectrin-based membrane skeleton in generating epithelial polarity, we characterized the distribution of membrane skeletal components in Drosophila ovarian follicle cells and in somatic clones of mutant cells that lack alpha-spectrin. Immunolocalization data reveal that wild-type follicle cells contain two populations of spectrin heterodimers: a network of alphabeta heterodimers concentrated on the lateral plasma membrane and an alphabetaH population targeted to the apical surface. Induction of somatic clones lacking alpha-spectrin leads to follicle cell hyperplasia. Surprisingly, elimination of alpha-spectrin from follicle cells does not appear to prevent the assembly of conventional beta-spectrin and ankyrin at the lateral domain of the follicle cell plasma membrane. However, the alpha-subunit is essential for the correct localization of betaH-spectrin to the apical surface. As a consequence of disrupting the apical membrane skeleton a distinct sub population of follicle cells undergoes unregulated proliferation which leads to the loss of monolayer organization and disruption of the anterior-posterior axis of the oocyte. These results suggest that the spectrin-based membrane skeleton is required in a developmental pathway that controls follicle cell monolayer integrity and proliferation. 相似文献
60.