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Biomedical subjects

Y Mizuguchi

Publications and source records attributed to Y Mizuguchi.

At least 73 records · Page 4Linked to original sources
PubMed1987

In vitro effects of monobactams on Legionella pneumophila.

The effects of azthreonam and carumonam against Legionella pneumophila Philadelphia-1 strain in liquid medium and in phagocytic cells were examined. The minimum inhibitory concentration (MIC) of azthreonam for the bacteria was 12.5 micrograms/ml at a concentration of 1.4 X 10(4) colony forming units (CFU) and 25 micrograms/ml at a concentration of 1.4 X 10(5) CFU. MIC of carumonam was 25 micrograms/ml in both concentrations of the bacterial suspension. In guinea pig macrophages, both azthreonam and carumonam at a concentration of 100 micrograms/ml did not inhibit the multiplication of the bacteria.

Animals↗
PubMed1987

Inhibitory effect of capsular antigen of Vibrio vulnificus on bactericidal activity of human serum.

Opaque (Op) and translucent (Tr) colonial variants were isolated from Vibrio vulnificus strains. Op-type variants were more resistant than the isogenic Tr-type variants, but the survival rate of the Op-type variants varied with the strains. Antisera were prepared by immunizing rabbit with whole cells of Op and Tr variants of some strains, in which the difference of the sensitivity between Op and Tr cells was remarkable. Then agglutination tests with their living and heat-killed cells were carried out. The results suggested the presence of capsular antigen in Op cells and its absence in Tr cells, with the exception of the existence of a slight amount of capsular material in Tr variants of strain L-180. The thin capsular layer of Tr cells of strain L-180 was also demonstrated electron microscopically, but the layer was thinner than that of the isogenic Op cells. Results of determination of sugar content in the extracted capsular fraction also showed that Op to Tr transformation was due to loss of capsular antigen of the cells. These results confirmed the morphological studies previously reported which suggested the prevention of host defense system by the capsular material of the vibrio.

Agglutination Tests↗
PubMed1987

Fate of Legionella pneumophila Philadelphia-1 strain in resident, elicited, activated, and immune peritoneal macrophages of guinea pigs.

Legionella pneumophila is known to grow intracellularly in resident peritoneal macrophages of guinea pigs. The present study was done to determine what kinds of macrophage stimulants are able to activate guinea pig macrophages to inhibit intracellular growth of the organism. Peritoneal macrophages were harvested from healthy guinea pigs, from guinea pigs injected intraperitoneally with proteose peptone (PP) or thioglycolate medium, from guinea pigs injected intraperitoneally with live Mycobacterium bovis BCG or killed Propionibacterium acnes (Corynebacterium parvum), and from guinea pigs surviving infection with live L. pneumophila. After in vitro phagocytosis, the L. pneumophila CFU in each well were counted on charcoal-yeast extract agar plates. In the macrophages elicited by PP or thioglycolate medium, the organism grew as well as it did in resident macrophages. In BCG-activated and immune macrophages, growth was inhibited almost completely. In P. acnes-activated macrophages, the initial growth of L. pneumophila was inhibited to some extent, but its growth reached the same level as in the resident and PP-induced macrophages after 3 or 4 days of culture. In the lethal challenge experiments in vivo, the superior protection provided by BCG over P. acnes was ascertained and the importance of macrophages in resistance to L. pneumophila was confirmed. Difference of activation by BCG and P. acnes in relation to the inhibition of intracellular growth of L. pneumophila in guinea pig macrophages is discussed.

Animals↗
PubMed1987

Patterns and distribution of aminoglycoside-acetylating enzymes in rapidly growing mycobacteria.

Cell-free extracts from clinical, laboratory, and environmental isolates of Mycobacterium fortuitum, Mycobacterium smegmatis, Mycobacterium phlei, and Mycobacterium vaccae were tested for the presence of aminoglycoside-acetylating enzyme and compared with enzymes from gram-negative organisms. Acetylating activity was detected in all strains examined despite variable levels of aminoglycoside susceptibility. Substrate profiles revealed 2 different patterns of 3-N-acetyltransferase. One pattern exhibited broad substrate specificity including significant activity to fortimicin and was specific for Mycobacterium fortuitum strains, whereas the second pattern showed a much narrower substrate range and was observed for the other 3 environmental species. Both types of enzymes inactivated the antimicrobial activity of drug in vitro. The acetylation reaction of mycobacterial enzyme with radiolabeled acetyl coenzyme A was significantly inhibited by malonyl- (34.7%), propionyl- (21.3%), and butyryl- (12.5%) coenzyme A in the presence of adenosine-5'-triphosphate, whereas no inhibition could be observed for the type enzyme (3-N-acetyltransferase-III) from Pseudomonas aeruginosa suggesting the two enzymes are different. Thus all species of rapidly growing mycobacteria probably contain one of several different types of aminoglycoside acetyltransferases including some isolates and species without a resistance phenotype. The origin and specific function of these enzymes are not known.

Acetylation↗
PubMed1986

[Isolation of Legionella pneumophila from the UOEH cooling tower].

Twelve samples of water taken from the cooling tower of UOEH were examined for the presence of microorganisms belonging to the genus Legionella by using a new selective medium, Wadowsky-Yee-Okuda (WYO) medium. Three samples contained this organism and they were identified as Legionella pneumophila from their biochemical properties. Among the three contaminated samples, two yielded L. pneumophila serogroup 1 and 3, and the other contained only L. pneumophila serogroup 1. One of the samples of the contaminated cooling tower water was treated with sodium hypochlorite as a disinfectant, indicating that this agent is probably not effective in eliminating L. pneumophila from cooling tower water at that concentration. An effective method of disinfection for Legionella spp. in the cooling tower must be developed to prevent infection in the hospital.

Air Conditioning↗
PubMed1986

[Studies on the mutagenicity test methods: comparison of the screening methods using Salmonella typhimurium and Saccharomyces cerevisiae].

Twenty-two acridine compounds and eleven phenanthridinium derivatives were tested for the induction of mutation in both eukaryotic, Saccharomyces cerevisiae and bacterial, Salmonella typhimurium. Summarized and discussed about the relationships between mutagenic activity and chemical structure of their compounds. Some metal compounds were examined for the induction of mitotic crossing over, mitotic gene conversion and reversion in yeast. Furthermore, the effects of the cell growth at the presence of these metal compounds on the mutations induced by nitrous acid was also examined. Mutagenic susceptibility of the yeast to these metal compounds on the comparison to the bacteria and the mechanisms of metal mutagenicity were discussed.

Acridines↗
PubMed1986

Comparison of the nucleotide sequences of the genes for the thermostable direct hemolysin and the thermolabile hemolysin from Vibrio parahaemolyticus.

The nucleotide sequences of genes encoding the thermostable direct (TSD) hemolysin and the thermolabile (TL) hemolysin of Vibrio parahaemolyticus were determined. From the nucleotide sequence of the TSD hemolysin gene, it was revealed that the preprotein and the mature protein consisted of 189 amino acids and 165 amino acids, and that the molecular weights were 21.1 kDa or 18.5 kDa, respectively. Our data regarding TSD hemolysin were in complete agreement with previously published data. From the nucleotide sequence of the TL hemolysin gene, it was revealed that the preprotein and the mature protein consisted of 418 amino acids and 398 amino acids, and that the molecular weights were 47.5 kDa and 45.3 kDa, respectively. The GC content of the TSD hemolysin gene was 35.6%, while that of the TL hemolysin gene was 47.6% which is almost the same as that of V. parahaemolyticus genome. Maxicell analysis revealed that the molecular weights of the proteins encoded by the TSD hemolysin gene were 22.0 and 19.5 kDa, and that of the protein encoded by the TL hemolysin gene was 45.5 kDa, and that the promoters of these two hemolysin genes of V. parahaemolyticus were functional in Escherichia coli.

Amino Acid Sequence↗
PubMed1986

Salt-induced filamentous growth of a Salmonella strain isolated from blood.

A strain of Salmonella choleraesuis subsp. choleraesuis serovar paratyphi-A isolated from the blood of a febrile patient grew into filaments on a nutrient agar containing various salts, such as NaCl, KCl, MgCl2, NH4Cl, (NH4)2SO4, or (NH4)2HPO4, at concentrations of 50 to 400 mM. The filamentous cells were nonseptate and multinucleate, and they had colony-forming ability. This mutant strain, however, did not show filamentous growth in liquid media which contained the same salts. On nutrient agar containing 20% sucrose but no salts, some of the cells formed large spheroplasts. Both ampicillin treatment and in vivo environment may in part be responsible for the induction of the mutant strain.

Adolescent↗
PubMed1986

Multiplication of Legionella pneumophila Philadelphia-1 in cultured peritoneal macrophages and its correlation to susceptibility of animals.

Intracellular growth of Legionella pneumophila Philadelphia-1 strain in peritoneal macrophages (PMP) from various rodents was measured and its correlation to the level of susceptibility of the animal was examined. In guinea pig PMP, the organism grew well and the guinea pig was very susceptible to it (50% lethal dose, LD50 = 7.6 X 10(4)). On the other hand, the bacteria hardly multiplied in mouse PMP and the animal was resistant to infection (LD50 = 6.7 X 10(7)). Intracellular growth rate correlated well with susceptibility in these animals. In golden hamsters, a discrepancy between intracellular growth and susceptibility was found. The organism grew intracellularly as rapid as in guinea pig PMP, but the golden hamster was very resistant to infection (LD50 = 2.2 X 10(8)). In rat PMP, the organism did not grow intracellularly during a 24-h period of infection, but started to grow after that and the growth rate thereafter was as rapid as in guinea pig PMP. WKA rats were resistant and the LD50 in the animal was 1.9 X 10(7). In vivo natural resistance of rats and golden hamsters to the organism was considered to be a result of other factors than macrophages.

Animals↗
PubMed1986

Biochemical mechanisms of antibiotic resistance in a clinical isolate of Mycobacterium fortuitum. Presence of beta-lactamase and aminoglycoside-acetyltransferase and possible participation of altered drug transport on the resistance mechanism.

Mycobacterium fortuitum was isolated from specimens of bone marrow from a patient with chronic osteomyelitis. This isolate was resistant to most antimycobacterial drugs, aminoglycosides, and beta-lactam antibiotics. Cell-free extracts from the clinical isolate contained an aminoglycoside acetyltransferase and beta-lactamase. On the basis of substrate specificity, the former enzyme was identified as the acetyltransferase (3), subtype III or IV. However, no positive correlation could be observed between resistance levels (minimal inhibitory concentrations) and the degree of inactivation of aminoglycosides. In vitro, the enzyme reaction required 40 to 60 min to completely inactivate kanamycin. Protein synthesis by ribosomes prepared from this clinical isolate was inhibited by one tenth the concentration of aminoglycosides required to inhibit growth of whole cells. These results suggest that some crypticity factor(s), such as the decreased permeability of drugs, may participate in the intrinsic resistance of the organism.

Acetyltransferases↗
PubMed1985

Effects of tetracyclines on experimental Legionella pneumophila infection in guinea-pigs.

The activities of tetracycline, doxycycline and minocycline against Legionella pneumophila strain Philadelphia-1 were compared in vitro, in peritoneal macrophages and in-vivo experiments in guinea-pigs. Minocycline was the most effective in in-vitro minimum inhibitory concentration assays. In the assay measuring inhibitory effects of drugs on intracellular bacterial multiplication, minocycline and doxycycline were equally effective and tetracycline was the least effective of the three. In-vivo experiments were carried out using guinea-pigs infected intraperitoneally. From the analysis of cumulative survival rates, only minocycline had statistically significant effects. Doxycycline, however, did significantly prolong the infected animals' survival days. These data lend some support to the case reports showing that tetracycline derivatives are effective in the treatment of Legionnaires' disease.

Animals↗
PubMed1985

Morphological changes induced by beta-lactam antibiotics in Mycobacterium avium-intracellulare complex.

In vitro activity of seven beta-lactam antibiotics against strains of Mycobacterium avium-intracellulare was evaluated by the agar dilution method. The activity was influenced by the presence or absence of Tween 80 in Dubos medium, and cephazolin and cefotaxime were effective against most strains in the presence of Tween 80. beta-Lactam antibiotics at low concentrations induced long filamentous cells with branching. In contrast to the filaments induced by ampicillin, in which septation was rarely observed, filaments induced by cephazolin had many septa, suggesting that the mechanisms of filament induction were different from the drugs used. At high concentrations, ampicillin and cephazolin induced osmotically sensitive cells with bulging at polar end of the cells. Analysis of penicillin binding proteins (PBPs) of the organism showed that there were at least nine PBPs with molecular weights between 32,000 and 94,000 in the cytoplasmic membrane. Ampicillin showed the highest affinity for PBPs 1a or 1b, or both, and also PBPs 3a or 3b, or both. In contrast, there was very little specificity of binding of cephazolin for any of the PBPs.

Anti-Bacterial Agents↗
PubMed1985

Relation of capsular materials and colony opacity to virulence of Vibrio vulnificus.

Colonies which varied in opacity were isolated from the four strains of Vibrio vulnificus. Opaque and translucent colonial types of the strains were distinguished from the corresponding parent strains. Variation in the opacity of colonies formed by each strain was accompanied by variation of capsular material formation, which was clarified by electron microscopy of the organisms stained with ruthenium red. The opaque-type colonies of the strains had capsular materials. On the other hand, three translucent-type colonies had no observable capsular materials, and one had incomplete capsular materials, in contrast to the corresponding opaque type. The corresponding opaque and translucent types of the strains were compared for points of virulence in mice and guinea pigs. By having capsular materials, the bacterial strains acquired resistance to serum bactericidal action, antiphagocytic activity, high lethality for mice, and strong invasiveness in the subcutaneous tissue of guinea pigs. Capsular materials of V. vulnificus were considered to be important for the expression of virulence.

Animals↗
PubMed1985

Cloning and expression in Escherichia coli of Vibrio parahaemolyticus thermostable direct hemolysin and thermolabile hemolysin genes.

Two hemolysin genes of Vibrio parahaemolyticus WP1, a thermostable direct (TSD) hemolysin gene and a thermolabile hemolysin gene, were cloned into the pBR322 vector in Escherichia coli K-12 C600. A large amount of the TSD hemolysin produced in E. coli K-12 accumulated in the periplasmic space. The TSD hemolysin gene was localized on a 0.9-kilobase HindIII-BamHI fragment by identifying qualitatively the production of the TSD hemolysin by a reverse passive hemagglutination assay in the osmotic shock fluid. The thermolabile hemolysin gene was isolated on a 1.3-kilobase HindIII-PstI fragment by selection with the hemolysin on blood agar. Southern blot hybridization and colony hybridization experiments indicated that the TSD hemolysin gene was present in the chromosomal DNA of 15 Kanagawa phenomenon-positive strains but not in 14 negative strains, whereas the thermolabile hemolysin gene was detected in all strains. No homologous DNA sequences to TSD and thermolabile hemolysin genes were detected in the chromosomes of Vibrio cholerae, Vibrio vulnificus, non-O1 V. cholerae, and Vibrio anguillarum.

Cloning, Molecular↗
PubMed1985

[CA 15-3 is present as a novel tumor marker in the sera of patients with breast cancer and other malignancies].

As a novel tumor marker, we employed a quantitative sandwich RIA system utilizing two monoclonal antibodies (115D8, DF3) which react with a circulating antigen expressed by human breast cancer cells. The optimum condition for this assay was found be a 60 minute incubation at 37 degrees C for the first reaction and a 60 minute one at 25 degrees C for the second reaction. Under these optimum conditions, intra-assay variation of control sera was CV 3.6% and inter-assay variation was CV 6.6%. The observed range of CA 15-3 concentration in 75 healthy persons was 7.5 +/- 3.4 units/ml (mean +/- SD) and mean +2 SD was 14.2 U/ml. Less than 15 U/ml was decided as the cut off level. The positive rate in 113 patients with benign diseases was 18%, the serum levels being less than 25 U/ml. Increased CA 15-3 levels in sera of 178 patients were found respectively, in 0%, 41%, 45%, 50% and 75% of stage I, II, III, IV in primary breast cancer and advanced breast cancer. The sera of 10 patients with advanced breast cancer were collected regularly during a 2 to 4 month period. All patients with PD showed increased CA 15-3 levels and four patients in PR showed a clear decrease of serum levels. In 167 other malignancies, increased levels were found in 76%, 63%, 58%, 33%, 32% and 22% of the sera from uterine, pancreatic, ovarian, prostatic, lung and gastric carcinomas. The data revealed that serum CA 15-3 was clinically useful as a tumor marker especially a monitoring marker of advanced breast cancer, but presently the assay is not suitable for the early detection of breast tumors. Also its measurement seemed to be useful in ovarian cancer, uterine cancer, pancreatic cancer and adenocarcinoma of the lung.

Antigens, Neoplasm↗
PubMed1984

[Mutagenesis of amino and/or methyl analogs of acridine in Salmonella and yeast: a comparison between the spot-test and the pre-incubation methods].

The relationship between mutagenic activities and chemical structure of acridine derivatives was examined by using Salmonella typhimurium strains TA 1537 and TA 1977 and yeast Saccharomyces cerevisiae. Most analogs with amino and/or methyl group(s) caused frameshift-type mutation in Salmonella without mammalian microsomal enzyme activation. The 9-amino analogs were strong mutagens and mutagenicity was also increased when 10-position was methylated in 1-amino and 2-amino compounds. However, 9-amino derivatives did not cause mitochondrial mutation in yeast, where 3,6-diamino and/or 10-methyl groups were structural requisites for significant mutagenic activity. In comparison with the pre-incubation method, the spot-test method was shown to be less sensitive. The mutagenicity of some compounds could not be detected by the spot-test method. Mutagenic activities of these drugs were revealed and increased markedly with an increase in pre-incubation period up to 20 min, suggesting that the pre-incubation of tester bacteria with a compound prior to a mutagenicity assay is necessary for the detection of mutagenesis of these compounds.

Acridines↗