Biomedical subjects

H Oyaizu

Publications and source records attributed to H Oyaizu.

At least 37 records · Page 2Linked to original sources

PubMed1999

Influences of copper forms on the toxicity to microorganisms in soils.

Soil samples with wide ranges of pH (4.9 to 8.1), organic carbon (0.1 to 77%), and total Cu contents from 32 to 11700 mg kg(-1), collected near a copper mine, were used to investigate the relationships between microbial features and Cu speciation in order to clarify the form(s) of Cu adversely affecting microorganisms. The effects of Cu on soil microorganisms were evaluated by two indicators: the ratio of microbial biomass carbon to soil organic carbon (Cmic/Org-C) and Cu tolerance level of bacterial community (IC50). The sequential extraction scheme of McLaren and Crawford (1973) was used to quantify the different Cu forms (soluble and exchangeable, specifically adsorbed, and organically bound). These influences were investigated using simple correlation analysis, multiple regression analysis, and principal component analysis. The IC50 was positively correlated with the log concentration of soluble and exchangeable Cu (Ex-Cu) (r = 0.757, P<0.01). The IC50 value was also influenced by the amount of specifically adsorbed Cu. The Cmic/Org-C ratio was not significantly correlated with any Cu forms. Thus, other soil properties had more influence on the size of microbial biomass carbon in the soils used. The amount of Ex-Cu exerting high toxicity was affected by pH and the amount of total Cu.

Carbon↗

PubMed1999

Usefulness of the sensitivity-resistance index to estimate the toxicity of copper on bacteria in copper-contaminated soils.

Examination was made of the fluctuations of numbers of the total bacteria and copper (Cu)-resistant bacteria with soluble/exchangeable Cu (Ex-Cu) fraction in three types of soils spiked with Cu at four concentrations. Drastic increase in Cu-resistant bacteria was observed in three soils spiked with 20 mmol Cu kg(-1) after 2 weeks of incubation, indicating the strong selection of individuals originally resistant to Cu. Adaptation and proliferation of bacteria were also observed in the soil environment under the long-term exposure to extremely high concentration of Cu (800 mg kg(-1) soil of Ex-Cu), deriving from the development of Cu resistance. These bacterial fluctuations and the toxic effects of Cu depended on soil types, due to the chemical forms in which Cu occurs. It was also found that the ratio of Cu-resistant bacterial number to total bacteria was significantly correlated with the amount of Ex-Cu in the soils. This sensitivity-resistance index seems to be useful for evaluating the toxic effects of Cu on the soil bacterial community. Whereas the toxicity of Cu depended on the soil properties, they also changed with time. This phenomenon can be explained by the decrease in the most labile Cu phase, Ex-Cu, with time in the soils.

Adaptation, Physiological↗

PubMed1999

A crucial role of caspase 3 and caspase 8 in paclitaxel-induced apoptosis.

The anticancer drug paclitaxel is well known as an inhibitor of microtubule depolymerization, resulting in mitosis arrest. We investigated the mechanism underlying antitumor effects of paclitaxel on the lung adenocarcinoma cell line LC-2-AD. Less than 10 microg/ml paclitaxel induced mitosis arrest upon LC-2-AD, followed by apoptosis, but more than 30 microg/ml paclitaxel induced apoptosis without mitosis arrest. LC-2-AD with less than 1 microg/ml paclitaxel showed a loss of mitochondrial transmembrane potential (deltapsim), which correlated with antitumor effects. However, LC-2-AD with more than 10 microg/ml paclitaxel showed slight changes in the loss of deltapsim in spite of its ability to induce apoptosis significantly. The cleavage of caspase 3, caspase 8, and DFF45/ICAD was also observed in paclitaxel-induced apoptosis, and the inhibitor of caspase 3 and caspase 8 inhibited both antitumor effects and apoptosis induced by paclitaxel. These results suggest that activation of caspase 3 and caspase 8 plays a crucial role in paclitaxel-induced apoptosis under any concentrations of paclitaxel.

Antineoplastic Agents, Phytogenic↗

PubMed1999

Distribution of bifidobacterial species in human intestinal microflora examined with 16S rRNA-gene-targeted species-specific primers.

In order to clarify the distribution of bifidobacterial species in the human intestinal tract, a 16S rRNA-gene-targeted species-specific PCR technique was developed and used with DNAs extracted from fecal samples obtained from 48 healthy adults and 27 breast-fed infants. To cover all of the bifidobacterial species that have been isolated from and identified in the human intestinal tract, species-specific primers for Bifidobacterium longum, B. infantis, B. dentium, and B. gallicum were developed and used with primers for B. adolescentis, B. angulatum, B. bifidum, B. breve, and the B. catenulatum group (B. catenulatum and B. pseudocatenulatum) that were developed in a previous study (T. Matsuki, K. Watanabe, R. Tanaka, and H. Oyaizu, FEMS Microbiol. Lett. 167:113-121, 1998). The specificity of the nine primers was confirmed by PCR, and the species-specific PCR method was found to be a useful means for identifying Bifidobacterium strains isolated from human feces. The results of an examination of bifidobacterial species distribution showed that the B. catenulatum group was the most commonly found taxon (detected in 44 of 48 samples [92%]), followed by B. longum and B. adolescentis, in the adult intestinal bifidobacterial flora and that B. breve, B. infantis, and B. longum were frequently found in the intestinal tracts of infants. The present study demonstrated that qualitative detection of the bifidobacterial species present in human feces can be accomplished rapidly and accurately.

Adult↗

PubMed1999

Comparison of gene arrangements of chloroplasts between two centric diatoms, Skeletonema costatum and Odontella sinensis.

We have cloned and sequenced 3.4 kbp, 2.5 kbp, 1.9 kbp, 1.6 kbp and 0.5 kbp segments of a marine centric diatom, Skeletonema costatum, chloroplast DNA. These segments contain 28 genes. The genes which are not encoded on chloroplast genomes of chlorophyll a+b plants are found such as the psaD, ycf33, ycf35 and ycf47 genes. The gene sequences were compared with that of Odontella sinensis. At nucleic acid level, the ycf genes have lower homologies (69-87%) with O. sinensis than the other genes (78-100%), and some differences in the gene arrangement are found between two centric diatoms, O. sinensis and S. costatum.

Chloroplasts↗

PubMed1999

Apoptosis of colorectal adenocarcinoma induced by 5-FU and/or IFN-gamma through caspase 3 and caspase 8.

The cytotoxic effect of 5-FU has been shown by the induction of apoptosis in cancer cells, and reported to be enhanced by IFN-gamma. We examined the role of caspases on the apoptosis induction of 5-FU and IFN-gamma using a colorectal adenocarcinoma cell line. The activities of caspase 3 and caspase 8 increased when apoptosis was induced by 5-FU and/or IFN-gamma. Moreover, all apoptotic cells showed high caspase 3 activity in these conditions. Although the inhibitors of caspase 3 and caspase 8 inhibit apoptosis, anti-Fas ligand antibody does not affect the apoptosis induced by 5-FU. Thus, caspase 3 and caspase 8 play crucial roles in apoptosis induced by 5-FU and/or IFN-gamma, regardless of the Fas-Fas ligand system.

Adenocarcinoma↗

PubMed1998

Rapid identification of human intestinal bifidobacteria by 16S rRNA-targeted species- and group-specific primers.

On the basis of 16S rRNA sequences, species- and group-specific primers for Bifidobacterium adolescentis, B. angulatum, B. bifidum, B. breve, the B. catenulatum group (B. catenulatum and B. pseudocatenulatum), and the B. longum group (B. longum and B. infantis), which are species commonly found in human intestinal tracts, were developed. The specificity of these primers was confirmed through the use of DNA extracted from 46 strains of 31 Bifidobacterium species, as well as 14 non-bifidobacterial species that are the predominant bacteria in the human intestinal tract. The present species-specific primers were applied to the identification of 43 isolated strains, consisting of six strains of B. adolescentis, eight of the B. catenulatum group, seven of B. bifidum, nine of B. breve, and 13 of the B. longum group.

Adult↗

PubMed1998

Phylogenetic analysis of the genus Bifidobacterium and related genera based on 16S rDNA sequences.

The 16S rRNA gene sequences were determined for type strains of 21 Bifidobacterium species. A phylogenetic tree was constructed using the determined sequences and sequences from DNA databases, which contain the sequences of 11 type strains of Bifidobacterium species and 11 strains of related genera. All species of the genus Bifidobacterium and Gardnerella vaginalis ATCC 14018 belonged to a cluster phylogenetically distinct from the other genera. The cluster was divided into two subclusters: subcluster 1 composed of most species of Bifidobacterium and G. vaginalis, and subcluster 2 consisting of two species, B. denticolens and B. inopinatum; both of which were isolated from human dental caries. In the genus Bifidobacterium, four groups of species are known to be moderately to highly related by DNA-DNA hybridization. The four groups of species exhibited more than 99% similarity among their 16S rDNA sequences within each group. These results indicated that species with around 99% or more similarity in their 16S rDNA sequences should be confirmed for species identities.

Base Sequence↗

PubMed1998

[Hemophagocytic syndrome associated with tuberculosis and mycoplasma infection in two patients].

Patient 1: A 48-year-old man was admitted to Osaka Red Cross Hospital because of fever and dyspnea. Laboratory examination revealed pancytopenia, liver dysfunction and hematostatic abnormality. Chest radiographs obtained on admission revealed ground-glass opacity in both lung fields, and an analysis of arterial blood showed severe hypoxemia (PaO2:46.8 Torr). Pulse therapy with methylprednisolone was started. Although the hypoxemia subsided and radiographic findings rapidly improved, pancytopenia persisted. Examination of bone marrow aspirate revealed mature histiocytes with marked hemophagocytosis. Amplified Mycobacterium tuberculosis direct tests of bronchoalveolar lavage fluid, sputum, urine, and bone marrow were all positive, and Mycobacterium tuberculosis was cultured from sputum and urine. Although the patient was taking antituberculous agents, his pancytopenia persosted. Treatment with etoposide induced remssion. Patient 2: A 19-year-old woman was admitted to Osaka Red Cross Hospital because of prolonged cough and fever. Laboratory examination revealed leukocytosis, liver dysfunction, and hematostatic abnormality. Serologic tests provided conclusive evidence of Mycoplasma infection and a CRP test was strongly positive. Chest radiographs obtained on admission revealed infiltration shadows in the middle and lower lung fields on both sides, with left pleural effusion. An analysis of arterial blood showed hypoxemia (PaO2: 54.2 Torr). Examination of bone marrow and pleural effusion samples revealed mature histiocytes with marked hemophagocytosis. Although treatment with antibiotics and pulse therapy with methylprednisolone was started, the patients respiratory functions deteriorated. Endotracheal intubation was performed. Therapy with etoposide induced remission. Hemophagocytic syndrome associated with Mycoplasma infection and tuberculosis appears to be exceedingly rare. In these 2 cases, it was difficult to achieve remission with therapy for the underlying infections, but etoposide treatment was effective.

Adolescent↗

PubMed1997

Analysis of oil components and hydrocarbon-utilizing microorganisms during laboratory-scale bioremediation of oil-contaminated soil of Kuwait.

A huge amount of oil-contaminated soil remains unremediated in the Kuwait desert. The contaminated oil has the potentiality to cause pollution of underground water and to effect the health of people in the neighborhood. We have been studying bioremediation of Kuwait oil-contaminated soil. Chemical analyses of biodegraded compounds and isolation of petroleum hydrocarbon-decomposing microorganisms were carried out. From the chemical analyses, it was revealed that the decomposed compounds were mainly saturated fractions from alumina column chromatography and that the aromatic fractions were not decomposed well. Isolation of bacteria was carried out for eight kinds of hydrocarbons which are components of crude petroleum (n-hexadecane, 2,6,10,14-tetramethylpentadecane, 1,4-diisopropylbenzene, naphthalene, 1-methylnaphthalene, phenanthrene, anthracene, and perylene). Many of the n-hexadecane- and 2,6,10,14-tetramethylpentadecane-decomposing bacteria were isolated, but aromatic compound-decomposing bacteria were not enriched. It was concluded that the slow decomposition of aromatic compounds was due to the low population of aromatic compound-decomposing bacteria in the Kuwait desert soil.

Bacteria↗

PubMed1997

Laboratory-scale bioremediation of oil-contaminated soil of Kuwait with soil amendment materials.

A huge amount of oil-contaminated soil remains unremediated in the Kuwait desert. The contaminated oil has the potentiality to cause pollution of underground water and to effect the health of people in the neighborhood. In this study, laboratory scale bioremediation experiments were carried out. Hyponex (Hyponex, Inc.) and bark manure were added as basic nutrients for microorganisms, and twelve kinds of materials (baked diatomite, microporous glass, coconut charcoal, an oil-decomposing bacterial mixture (Formula X from Oppenheimer, Inc.), and eight kinds of surfactants) were applied to accelerate the biodegradation of oil hydrocarbons. 15% to 33% of the contaminated oil was decomposed during 43 weeks' incubation. Among the materials tested, coconut charcoal enhanced the biodegradation. On the contrary, the addition of an oil-decomposing bacterial mixture impeded the biodegradation. The effects of the other materials were very slight. The toxicity of the biodegraded compounds was estimated by the Ames test and the tea pollen tube growth test. Both of the hydrophobic (dichloromethane extracts) and hydrophilic (methanol extracts) fractions showed a very slight toxicity in the Ames test. In the tea pollen tube growth test, the hydrophobic fraction was not toxic and enhanced the growth of pollen tubes.

Biodegradation, Environmental↗

PubMed1997

The phylogeny of the genera Chryseomonas, Flavimonas, and Pseudomonas supports synonymy of these three genera.

The 16S rRNA sequences of Chryseomonas luteola, the type species of the genus Chryseomonas, and Flavimonas oryzihabitans, the type species of the genus Flavimonas, were determined. These sequences were compared with the sequences of 27 representative strains of the genus Pseudomonas. C. luteola and F. oryzihabitans were located in the cluster that contains Pseudomonas aeruginosa, the type species of genus Pseudomonas Migula 1894, and the levels of 16S rRNA sequence homology between P. aeruginosa and the other two species were more than 93.9%. All of the strains of the genus Pseudomonas sensu stricto whose sequences have been determined were included in the P. aeruginosa cluster. These results suggested that Chryseomonas, Flavimonas, and Pseudomonas are synonymous, and we concluded that Chryseomonas and Flavimonas are junior subjective synonyms of Pseudomonas.

Base Sequence↗

PubMed1997

Peculiar archaea found in Japanese paddy soils.

Archaeal 16S rDNA clones retrieved from paddy soil DNA were sequenced. Among 100 clones, 88 clones were assigned to methanogens and nine clones were assigned to crenarchaeota. However, three of the nine clones were phylogenetically far from the cultured crenarchaeota and closely related to marine planktonic archaea. The other three clones showed extremely novel 16S rDNA sequences and were phylogenetically far from both Crenarchaeola and Euryarchaeota. This paper reports the ubiquitous presence of crenarchaeotal and extremely novel clones in paddy soils.

Archaea↗

PubMed1996

Cloning and sequence analysis of czc genes in Alcaligenes sp. strain CT14.

We have isolated 14 cadmium (Cd)-resistant, soil-borne bacteria. Among those, strain CT14, which was identified as an Alcaligenes sp., has a czc (cadmium, zinc, and cobalt divalent cation resistant determinant) system. Here we report the nucleotide sequence of 4 genes (czcCBAD) of the system. CzcCBA showed over 98% identity with those of A. eutrophus CH34, however, CzcD, the distal gene product, was 117 amino acids longer than that (199 amino acids) of A. eutrophus CH34, and had considerable similarity to the members of the CDF (cation diffusion facilitator) family proteins all over the region.

Alcaligenes↗

PubMed1995

Nucleotide sequence of the SrRNA gene of Entamoeba gingivalis: applications for construction of a species-specific DNA probe and phylogenetic analysis.

The small subunit ribosomal RNA (SrRNA) gene of Entamoeba gingivalis was amplified by PCR and the product of 1.9-kbp sequence was cloned into a plasmid vector pUC18. Four clones were isolated and sequenced. The insert DNAs were 1918- to 1921-bp long and A+T rich (65.5%). The four SrRNA sequences of E. gingivalis were found to be aligned with those of nine related protozoans while searching for E. gingivalis-specific sequences. A sequence of 28 oligonucleotides was chosen, chemically synthesized, and labeled with digoxigenin for use as a DNA probe. The probe thus constructed was shown to hybridize only with either the SrRNA-coding DNAs or the cells of the two E. gingivalis strains and not with those of other protozons or oral fungi tested. A representative SrRNA-sequence was analyzed and a phylogenetic tree was constructed by the neighbor-joining (NJ) method. Among the protists examined, E. gingivalis was placed next to Entamoeba histolytica as expected from the traditional taxonomy.

Animals↗

PubMed1995

Morphological variation of new Thermoplasma acidophilum isolates from Japanese hot springs.

We isolated 12 strains of Thermoplasma acidophilum from hot springs in Hakone, Japan. T. acidophilum strains showed morphological variation in the crystal-like structure in the cell and the fibrous structure on the cell surface. Two strains tested were sensitive to novobiocin. However, a novobiocin-resistant mutant was obtained by spontaneous mutation.

Base Composition↗

PubMed1994

Phylogenetic evidence for Sphingomonas and Rhizomonas as nonphotosynthetic members of the alpha-4 subclass of the Proteobacteria.

To clarify the taxonomic relationships of the genera Rhizomonas and Sphingomonas, the 16S rRNA sequence of Rhizomonas suberifaciens IFO 15211T (T = type strain) was determined. A phylogenetic analysis of aligned 16S rRNA gene sequences revealed that eight species of the genus Sphingomonas and R. suberifaciens are closely related to Erythrobacter longus and Porphyrobacter neustonensis and, therefore, belong in the alpha-4 subclass of the Proteobacteria. Within this subclass, Sphingomonas species and R. suberifaciens are phylogenetically interrelated and comprise several subgroups. Our findings show that the genus and species definitions of these organisms are in need of revision.

Bacteriochlorophylls↗

PubMed1993

Phylogenetic relationships of marine bacteria, mainly members of the family Vibrionaceae, determined on the basis of 16S rRNA sequences.

The phylogenetic relationships of 50 reference strains, mostly marine bacteria which require Na+ for growth, were determined on the basis of 600 16S rRNA nucleotides by using reverse transcriptase sequencing. Strains belonging to 10 genera were included (four genera of the family Vibrionaceae, the genus Aeromonas of the family Aeromonadaceae, and the genera Alteromonas, Marinomonas, Shewanella, Pseudomonas, and Deleya). The sequences were aligned, the similarity values and evolutionary distance values were determined, and a phylogenetic tree was constructed by using the neighbor-joining method. On the basis of our results, the family Vibrionaceae was separated into at least seven groups (genera and families). Vibrio marinus clearly was on a line of descent that was remote from other vibrios. As determined by the similarity and evolutionary distance values, V. marinus is more distantly related to the family Vibrionaceae than the members of the Aeromonadaceae are. Also, Vibrio cholerae strains formed a separate group with Vibrio mimicus at the genus level. Of 30 species of the Vibrionaceae, 17 formed a large phylogenetic cluster. The genus Listonella was found to be a heterogeneous group, and the species were distributed in various subgroups of the Vibrionaceae. The separation of the family Aeromonadaceae from the family Vibrionaceae and the separation of the genera Marinomonas and Shewanella from the genus Alteromonas were confirmed in this phylogenetic study. However, a marine Pseudomonas species, Pseudomonas nautica, was clearly separated from two terrestrial Pseudomonas species. Each group that was separated by the phylogenetic analysis had characteristic 16S rRNA sequence patterns that were common only to species in that group. Therefore, the characteristic sequences described in this paper may be useful for identification purposes.

Base Sequence↗