Microbios最新文献

The iutA gene from marine Vibrio species SD004, which encoded a ferric aerobactin receptor for the uptake of iron(III), was cloned onto a multicopy plasmid, pUC 18, in Escherichia coli. Identification of the positive clone was achieved on the basis of its deferrization activity and was detected as a halo formation on the chrome azurol S (CAS)-containing selective plate. Nucleotide sequence analysis of the cloned DNA fragment revealed an open reading frame (ORF) which encoded a polypeptide of 706 amino acid residues, and the deduced molecular mass of this polypeptide was 77.906 kD. The amino acid sequence showed a 41% homology with that of the lutA protein from E. coli. The cloned gene was iutA, which encoded the ferric aerobactin receptor. Another incomplete ORF was found 100 bp upstream of the iutA gene, which was homologous (31 out of 49 amino acids) with the C-terminal region of the luc D protein of E. coli. It is suggested that aerobactin biosynthesis and the transport genes are located tandemly on the Vibrio chromosome and may form an aerobactin operon.

A new hepatitis virus, named GBV-C or hepatitis G virus (HGV), closely related to the hepatitis C virus (HCV), was identified in 1994. The existence of quasispecies in HCV is very important. In this work polymerase chain reaction amplification of the NS3 region of the genome of GBV-C/HGV and heteroduplex mobility assay (HMA) were combined to investigate the presence of quasispecies in patients with chronic infection by GBV-C/HGV. Patients with chronic infection by HCV were used to validate the method. The HMA was also used to investigate the similarity between the cited genomic region of GBV-C/HGV in different infected patients. A high degree of heterogeneity was found for HGV existing as quasispecies and as differences between samples. This is of extreme importance because of the intrinsic clinical and pathogenic implications of quasispecies of a virus capable of producing disease, and is in accord with other studies which report on the genomic variability of the NS3 region.

Four enzyme-linked immunosorbent assays designated test 1 (ETI-HSVK-G 1/2); test 2 (ETI-HSVK-M 1/2); test 3 (ETI-HSVK-G 2), and test 4 (BioElisa HSV2 IgG) were studied to evaluate different stages of herpes simplex virus (HSV) infection. Samples (50 sera and 14 cerebrospinal fluid) were included in four groups. Group 1 consisted of samples from patients with primary HSV infections; group 2 comprised samples from patients with recurrent HSV infections; group 3 were samples nonreactive to HSV; and group 4 were samples from patients with infections by other herpes viruses (4a, chickenpox; 4b, herpes zoster; and 4c, infectious mononucleosis by Epstein-Barr virus). The percentages of agreement between tests 1 and 2 were 100 and 72.1%, respectively. The total diagnostic values of tests 1 and 2 were: 100 and 50% sensitivity, respectively; and 100 and 89% specificity, respectively. Few positive results for HSV-2 infection were found, and so, tests 3 and 4 were not evaluated. The results of tests 3 and 4 for a chickenpox patient, and a herpes zoster patient were not in agreement.

The disinfectant effects on Legionella and nontuberculous mycobacteria of hot water, ultraviolet light, silver ions and chlorine, were evaluated. The bacterial strains Legionella pneumophila ATCC33152 and Mycobacterium avium ATCC25291 and strains of L. pneumophila and M. avium which had been isolated from a 24 h bath, were examined for their resistance to treatments. All strains were killed within 3 min on exposure to hot water at 70 degrees C and exposure to ultraviolet light at 90 mW.s/cm2. The strains of L. pneumophila tested were killed within 6 h on exposure to a solution of silver ions at 50 micrograms/l. The number of viable cells of strains of M. avium fell from 10(5) CFU/ml to 10(3) CFU/ml after exposure to an aqueous solution of silver ions at 100 micrograms/l for 24 h. Chlorine effectively killed strains of Legionella which were exposed to an aqueous solution of chlorine at 2 mg/l within 3 min, but strains of Mycobacterium survived exposure to chlorine at 4 mg/l for more than 60 min.

A hydrophilic compound with siderophore activity was isolated from a culture of Yersinia enterocolitica 4-32 grown in an iron-deficient medium. It was found that the siderophore secreted did not belong to the catecholamide and hydroxamate type of siderophores and not yersiniabactin. Supplementation of cultures of Y. enterocolitica 4-32 with sodium chloride (300 mM) resulted in a decrease in the production of siderophores.

The minimum inhibitory concentrations (MIC) of eight common dental antibacterial agents against three genera of bacteria which have been implicated in dentine caries, namely streptococci, lactobacilli and actinomycetes were investigated. The ultimate aim was to determine the most appropriate antibacterial agent which could be added to dental restorative materials for filling cavities where there was residual dentine caries. The antibacterial agents tested were chlorhexidine diacetate, chlorhexidine dihydrochloride, chlorhexidine gluconate, benzalkonium chloride, cetrimide, cetylpyridinium chloride, thymol and sodium hypochlorite. Thymol and sodium hypochlorite did not inhibit microbial growth at any of the concentrations tested. For the active antibacterial agents tested the MIC values against lactobacilli and streptococci were 0.25 microg/ml to 8.0 microg/ml and for actinomycetes 0.125 to 8.0 microg/ml. These results illustrate the wide spectrum of sensitivity of caries associated bacteria against dental antibacterial agents. From the MIC values alone, it is difficult to recommend which of the active antibacterial agents would be most effective in eliminating cariogenic organisms.

To elucidate the role of dopamine as a neuromediator in the adrenocorticotropic hormone (ACTH) secretion, investigations were carried out with dopaminergic pharmacology drugs on male white Wistar rats. In the first series of experiments, the effects of 200 mg/kg body wt L-DOPA, of the combination of 200 mg/kg L-DOPA and 50 mg/kg body wt carbidopa, and of 2.5 mg/kg body wt bromocriptine, after a single intraperitoneal injection of ACTH in the serum of rats after 30, 90 and 120 min, following the injection, were studied. In the second series of experiments, the effect of 200 mg/kg body wt L-DOPA, of the combination of 200 mg/kg body wt L-DOPA and 50 mg/kg body wt carbidopa, of 1 mg/kg body wt bromocriptine, after intraperitoneal injection, on the concentration of ACTH in the serum within 7 days, were assessed. The inhibition of agonists of dopamine after ACTH secretion with repeated application has been shown. Using a radioimmunology assay with test kits, the amount of ACTH in the serum was determined.

Subclinical Candida infection has been suggested as one of the aetiological factors in patients with burning mouth syndrome (BMS). In order to investigate the possible factors which contribute to the relatively high isolation rate of Candida in BMS, parotid saliva samples (20 in toto) from patients with this condition were collected and the growth of Candida in each sample dynamically observed using a computerized turbidometric assay system. A total of thirteen parotid saliva samples obtained from healthy individuals served as normal controls. The results showed no significant growth differential within the test and control saliva samples, when a single isolate each of Candida albicans and Candida tropicalis were cultured for 24 h, at 37 degrees C. A single isolate of Candida glabrata tended to grow better in the saliva from BMS patients than the controls. These results indicate that the composition of saliva may be a contributory factor for the high isolation rate of Candida in saliva of BMS patients.

The adherence characteristics of Bacteroides forsythus to host cells, was examined. Four laboratory strains and twelve clinical isolates of B. forsythus were used. All strains demonstrated different haemagglutination activities. The haemagglutination of B. forsythus was inhibited strongly by amino acids such as L-arginine, L-histidine, L-lysine and L-alanine. The adherence to polymorphonuclear leucocytes (PMNL) was weak except for B. forsythus ATCC 43037 and OMZ 408. The adherence of these strains was inhibited by L-histidine and L-arginine, and was facilitated by trypsin (0.1 mg/ml) treatment of polymorphonucleocytes. B. forsythus strains showed varied adherence to fibroblasts. It is suggested that the adherence of B. forsythus to host cells is mediated by a factor which is sensitive against some amino acids, and altered by trypsin-like enzymes.

The aim of this study was to determine whether antibodies to HCV can be hidden in immunocomplex aggregates in anti-hepatitis C virus (HCV) negative, HCV-RNA positive patients and whether their presence could be related to HCV viral load or HCV genotype. Sera (23 in toto) from patients with elevated alanine aminotransferase (ALT) levels and negative for anti-HCV but positive for HCV-RNA and the immunocomplex aggregates (precipitate with PEG 6000 and glycine 1 M) were studied. The sera were treated using a rapid, simple new ELISA which disrupted the immunocomplex aggregates. Sera from ten patients were tested anti-HCV positive after immunocomplex disruption. No correlation with age, sex, ALT level, viral load or HCV genotype was observed. In some patients anti-HCV antibodies were hidden in circulating antibody/antigen complexes which could be dissociated with a simple, inexpensive and rapid protocol; therefore it can provide a valuable addition to the diagnosis of HCV infection and it may prevent some cases of post-transfusion hepatitis.