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Biomedical subjects

K Ohta

Publications and source records attributed to K Ohta.

At least 271 records · Page 15Linked to original sources
PubMed1998

Diesel exhaust particles stimulate human airway epithelial cells to produce cytokines relevant to airway inflammation in vitro.

BACKGROUND: Epidemiologic and experimental studies suggest that air pollution such as diesel exhaust particles (DEPs), one of the important air pollutants, may play a role in the increasing prevalence of allergic airway diseases. OBJECTIVE: We studied the effect of suspended particulate matter (SPM) and its main component, DEPs, on the production of IL-8 and granulocyte-macrophage colony-stimulating factor (GM-CSF) by human airway epithelial cells in vitro. METHODS: SPM obtained from high-volume air samplers and DEPs were added to cultured human nasal polyp-derived upper airway, normal bronchial, and transformed bronchial epithelial cells. Production of GM-CSF and IL-8 by airway epithelial cells was evaluated. RESULTS: Nontoxic doses of DEPs showed a significant stimulatory effect on IL-8 and GM-CSF production by these three kinds of epithelial cells in a dose- and time-dependent fashion. SPM had a stimulatory effect on GM-CSF, but not IL-8, production. These effects were abrogated by treatment with a protein synthesis inhibitor, cycloheximide, suggesting that the process required a de novo protein synthesis. On the double-chamber plates, airway epithelial cells responded to DEPs only when they were stimulated from the apical sides, which can be a model for in vivo environments. Neither charcoal nor graphite showed such stimulatory effects, indicating that the activity of DEPs did not derive from their particulate nature. Benzo(a)pyrene, one of the main aromatic hydrocarbons contained in DEPs, showed a stimulatory effect on the release of the cytokines, and this organic substance might have a causative effect on of the potency of DEPs. CONCLUSION: We conclude that SPM and DEPs, its main component, might be important air pollutants in the activation of airway epithelial cells for the release of cytokines relevant to allergic airway inflammation.

Allergens↗
PubMed1998

HLA-DRB1 alleles contribute to determining the prognosis of Japanese diabetes mellitus positive for antibodies to glutamate decarboxylase.

Diabetes mellitus positive for antibodies to glutamate decarboxylase is heterogeneous as far as the degree of impairment of endogenous insulin release, though antibodies to glutamate decarboxylase are the most useful marker for future insulin deficiency. To investigate what determines the prognosis of diabetes mellitus positive for antibodies to glutamate decarboxylase, we measured HLA-DRB1 alleles in three groups: 77 cases of insulin-dependent diabetes mellitus (IDDM), 44 of non-insulin-dependent diabetes mellitus (NIDDM) with secondary failure of oral hypoglycemic therapy, and 22 of NIDDM well controlled by diet and/or sulfonylurea agents. The proportion of susceptible and resistant alleles to IDDM determined the degree of insulin deficiency, and comparison of IDDM to NIDDM well controlled by diet and/or sulfonylurea agents revealed significant differences in DRB1*0405 (P < 0.05; RR = 2.82 and RR = 0.89, respectively) and DRB1*1502 (P < 0.001; RR = 0.02 and RR = 2.19, respectively). This study revealed that HLA-DRB1 alleles contribute to determining the prognosis of Japanese diabetes mellitus positive for antibodies to glutamate decarboxylase.

Adolescent↗
PubMed1998

Changes of amino acid levels and aspartate distribution in the cervical spinal cord after traumatic spinal cord injury.

To evaluate the role of excitatory amino acids in secondary injury occurring after spinal cord trauma, several experimental studies focusing on the the changes of amino acid levels in the spinal cord have been performed to date. However, because of technical limitations, it has not been possible to correlate the local changes of excitatory amino acids with the total tissue levels of excitatory amino acids. To investigate the connection between the spread of injury and the excitatory amino acids, we assessed, the local changes of aspartate through novel experimental approaches like immunoreactivity via fluorescence microphotometry and histopathology while also analyzing the total tissue levels of amino acids via HPLC. These studies were performed using a model of incomplete cervical spinal cord injury in rats. Through this approach, we found that the levels of excitatory amino acids, such as glutamate and aspartate, began to decrease immediately after injury. No significant decrease was observed in the other amino acids. Similarly, local changes in aspartate in the spinal cord were observed using fluorescence microphotometry. The decrease in the anterior and posterior horns was rapid up to 15 min after injury, but, slowed thereafter, suggesting that a release of excitatory amino acids occurred at the site of primary injury almost immediately following injury. At 15-min post-injury large neurons within the injured cord appeared intact on histopathological analysis demonstrating that the alteration of excitatory amino acids occurs prior to histopathological change. Histopathological change in the white matter occurred more slowly than in the anterior and posterior horns, suggesting the spread of the lesion by secondary damage due to an autoclastic mechanism.

Amino Acids↗
PubMed1998

Zymographic characterization of Staphylococcus aureus cell wall.

Susceptibilities of several preparations of Staphylococcus aureus cells to various peptidoglycan hydrolases with known bond specificity were analyzed by zymography. The substrates were intact S. aureus cells, cells boiled in the presence of SDS and cells treated with trichloroacetic acid after treatment with boiling SDS solution (TCA-cells). Twofold dilutions of lysostaphin (LS), lysozyme (LZ), S. aureus 51 kDa glucosaminidase (GL) or S. aureus 62 kDa amidase (AM) were electrophoresed, and the minimal enzyme dose showing a visible bacteriolytic band was defined as MBD (minimal bacteriolytic dose). Under the same experimental conditions, this method gave reproducible results. As the substrate for zymogram, TCA-cells were the most sensitive to LS, LZ and AM, whereas the three substrate were equally sensitive to GL. A zymographic analysis of methicillin-resistant S. aureus treated with methicillin together with previous studies suggest that this method can be used for the preliminary characterization of S. aureus cell wall peptidoglycan.

Amidohydrolases↗
PubMed1998

The activities of the Tokyo Center.

The main World Health Organization (WHO) activities of the Tokyo Center are as follows: (1) It performed the research project entitled 'A Bio-Psycho-Social Study on Children with Emotional and Behavioral Problems' in cooperation with the Beijing and Seoul Centers from 1985 to 1987. These results suggested that the deviant behavior of children in the general population had no biological background, but presumably stemmed from psychosocial disadvantages. (2) It has participated in a field trial for the proposed draft for chapter V of the ICD-10 as the Field Trial Coordinating Center in Japan since 1986 and the first Japanese edition of the ICD-10 Classification of Mental and Behavioral Disorders: Clinical Descriptions and Diagnostic Guidelines were published in 1993. (3) It proposed the collaborative project exploratory eye movements in patients with schizophrenia in 1989 and has promoted the project with the cooperation of six centers that included Beijing, Casablanca, Montreal, Munich, Prague and Sapporo. The findings of the present project indicated that exploratory eye movements may be specific to schizophrenia and can be practically used to discriminate schizophrenia without significantly depending on language.

Adolescent↗
PubMed1998

[Treatment of hepatosplenic candidiasis with liposomal amphotericin B in a patient with acute leukemia; a case report of the experience of use of liposomal amphotericin B].

We report a 26-year-old male patient with acute myelocytic leukemia and hepatosplenic candidiasis during his clinical course. His hepatosplenic candidiasis was refractoty to itraconazole and fluconazol. He developed serious side-effect such as renal dysfunction, when conventional amphotericin B was given. Then he was treated with liposomal amphotericin B (Abelcet). This therapy was safe and effective for him. He was able to be treated with 3075 mg of a liposomal amphotericin B. This was ten times as much as the dose of conventional amphotericin B which was given earlier until amphotericin B was stopped because of renal dysfunction. Liposomal amphotericin B seems to be a safe and effective therapy for systemic fungal infectin and should be considered more in Japan.

Adult↗
PubMed1998

A triazine dye, cibacron blue F3GA, decreases oxacillin resistance levels in methicillin-resistant Staphylococcus aureus.

Cibacron blue F3GA (CB) was found to reduce the MIC of oxacillin for methicillin-resistant Staphylococcus aureus (MRSA). This effect was not observed with methicillin-susceptible S. aureus. CB alters the resistance level of MRSA through a factor(s) other than mecA-related products, major autolysins, or femAB products. The exact target(s) of CB in causing the effect is unknown.

Drug Interactions↗
PubMed1998

Urokinase type plasminogen activator receptor expression in colorectal neoplasms.

BACKGROUND: The urokinase type plasminogen activator receptor (uPAR) may play a critical role in cancer invasion and metastasis. AIMS: To study the involvement of uPAR in colorectal carcinogenesis. METHODS: The cellular expression and localisation of uPAR were investigated in colorectal adenomas and invasive carcinomas by in situ hybridisation, immunohistochemistry, and northern and western blot analyses. RESULTS: uPAR mRNA expression was found mainly in the cytoplasm of dysplastic epithelial cells of 30% of adenomas with mild (19%), moderate (21%), and severe (47%) dysplasia, and in that of carcinomatous cells of 85% of invasive carcinomas: Dukes' stages A (72%), B (93%), and C (91%). Some stromal cells in the adjacent neoplastic epithelium were faintly positive. Immunoreactivity for uPAR was detected in dysplastic epithelial cells of 14% of adenomas and in carcinomatous cells of 49% of invasive carcinomas. uPAR mRNA and protein concentrations were significantly higher in severe than in mild or moderate dysplasia (p<0.05); they were notably higher in Dukes' stage A than in severe dysplasia (p<0.05), and significantly higher in Dukes' stage B than in stage A (p<0.05), but those in stage B were not different from those in stage C or in metastatic colorectal carcinomas of the liver. CONCLUSIONS: Colorectal adenoma uPAR, expressed essentially in dysplastic epithelial cells, was upregulated with increasing severity of atypia, and increased notably during the critical transition from severe dysplasic adenoma to invasive carcinoma. These findings implicate uPAR expression in the invasive and metastatic processes of colorectal cancer.

Blotting, Northern↗
PubMed1998

Retention mechanism of imidazoles in connective tissue. IV. Identification of a nucleophilic imidazolone metabolite in rats.

Formation of a nucleophilic 4(5H)(or 5(4H))-imidazolone structure has been postulated from in vitro studies to be one of the causative elements involved in the retention of drugs with imidazole moiety in connective tissue. To confirm this, we searched for the imidazolone-related metabolite in rats after intravenous dosing of 2-methylimidazole (2MI; 14C-labeled and unlabeled form, 3 and 300 micromol/kg body weight) as a model compound. The excreted urine, the major route of elimination of the compound, was collected and analyzed using the HPLC/MS system with a counterion effect for metabolite separation. 2-Methyl-4(5H)(or 5(4H))-imidazolone (2MIone) was identified as a urinary metabolite by chromatographic and mass-spectral inspection with the corresponding authentic standard. Pretreatment of rats with either SKF-525A (50 mg/kg, i.p.) or cimetidine (200 mg/kg, i.p.) significantly increased the excreted amount of 2MIone in urine and the irreversible binding of 2MI equivalents in the aortic tissue, whereas both factors were reduced by pretreatment with triethylenetetramine dihydrochloride (150 mg/kg/d for 5 d, s.c.). These results support the aforementioned deduction, and also raise the possibility that a cytochrome P450-independent, copper-related metabolic reaction might be involved in the imidazolone formation in vivo.

Animals↗
PubMed1998

Retention mechanism of imidazoles in connective tissue. II. Activation of imidazoles in cupro-ascorbate system for irreversible binding formation with aortic tissue in vitro.

In order to obtain an insight into the retention mechanism of drugs with imidazole moiety in the connective tissue, the in vitro characteristics of the interaction between 14C-labeled imidazoles (imidazole and its 2-methyl derivative) and slices of dog aorta were studied. We found that cupro-ascorbate-catalyzed oxidative reactions for the imidazoles led to their irreversible binding with connective tissue, and that, from a study using protein modifiers, the aldehydic function intrinsic to the tissue protein was involved in the binding formation. This characteristic in vitro was observed under physiological conditions, hence it can be extrapolated to the in vivo situation and could also give a clue to the nature of the retention of imidazole-containing drugs in connective tissue.

Animals↗
PubMed1998

An ergosterol peroxide, a natural product that selectively enhances the inhibitory effect of linoleic acid on DNA polymerase beta.

As described previously (Mizushina Y., Tanaka N., Yagi H., Kurosawa T., Onoue M., Seto H., Horie T., Aoyagi N., Yamaoka M., Matsukage A., Yoshida S., and Sakaguchi K., Biochim. Biophys. Acta, 1308, 256-262, 1996), linoleic acid (LA) inhibits the activities of mammalian DNA polymerases. We found a natural product from a basidiomycete, Ganoderma lucidum, that enhances this effect of LA in a special manner. The structure was identified to be an ergosterol peroxide, 5,8-epidioxy-5alpha,8alpha-ergosta-6,22E-dien -3beta-ol by spectroscopic analyses. The ergosterol peroxide (EPO) itself scarcely inhibited the activities of calf thymus DNA polymerase alpha (pol. alpha) or rat DNA polymerase beta (pol. beta). However, when EPO at 0.25 mM was present, 10 microM or less of LA almost completely inhibited the pol. beta activity, while almost complete inhibition by LA itself was achieved at 80 microM or higher. Interestingly, under the same conditions, EPO did not affect the LA-effect on pol. alpha. The action mode of the EPO was discussed.

Animals↗
PubMed1998

Potent retinoid synergists with a diphenylamine skeleton.

4-[N-(5,6,7,8-Tetrahydro-5,5,8,8-tetramethyl-2-naphthyl)amino]benzoic acid (5) exhibited weak retinoidal and retinoid synergistic activities in HL-60 cell differentiation assay. N-Alkylation of 5 caused decrease or loss of differentiation-inducing activity, but enhanced the synergistic activity with a synthetic retinoid Am80 (2), as reflected in the potent synergistic EC50 (SEC50) values of DA023 (11, 1.6 x 10(-10) M) and DA113 (14, 1.4 x 10(-10) M) in the presence of 1.0 x 10(-10) M Am80 (2).

Cell Differentiation↗
PubMed1998

Retention mechanism of imidazoles in connective tissue. III. Aldehyde adduct formation of a 4(5H)(or5(4H))-imidazolone product in vitro.

2-Methylimidazole (2MI), as well as imidazole, has been thought to undergo cupro-ascorbate (Cu-VC)-catalyzed oxidative transformation in vitro to become a reactive species capable of combining with aldehydes intrinsic to connective-tissue proteins. We attempted to seize the essence of the above reaction through obtaining the structural information of an aldehyde-bonding species. As major products from 2MI in the in vitro Cu-VC system, 2-hydroxymethylimidazole (2(OH)MI) and 2-methyl-4(5H)(or 5(4H))-imidazolone (2MIone) were identified by mass-spectral and chromatographic comparison with the corresponding authentic standards synthesized. The in situ addition of acetaldehyde or propionaldehyde as a simple protein-aldehyde model to the system resulted in the deducible formation of an aldol condensate, 2-methyl-4(or 5)-ethylidene-4(5H)(or 5(4H))-imidazolone (2MEIone) or its possible analogue with a propylidene moiety, respectively. The authentic compound of 2MIone directly reacted with acetaldehyde and easily afforded the products assignable to the isomers of 2MEIone through the ethylidene moiety at physiological pH and temperature, whereas neither 2MI or 2(OH)MI reacted at all. These results suggest that a 4(5H)(or 5(4H))-imidazolone product, although simply a monooxygenated form, is sufficiently reactive to give aldol condensation-typed covalent adducts with aldehydes, even under physiological conditions, probably having an activated methylene moiety in the ring structure. Based on the present results, we discussed the mechanism of the retention of imidazole-containing drugs in connective tissue.

Acetaldehyde↗
PubMed1998

Sulfoquinovosyldiacylglycerol, KM043, a new potent inhibitor of eukaryotic DNA polymerases and HIV-reverse transcriptase type 1 from a marine red alga, Gigartina tenella.

A new sulfolipid, KM043, which belongs to the 6-sulfo-alpha-D-quinovopyranosyl-(1-->3')-1',2'-diacylglycerol (SQDG) class of compounds, has been isolated from a marine red alga, Gigartina tenella, as a potent inhibitor of eukaryotic DNA polymerases and HIV-reverse transcriptase type 1. Its structure was determined on the basis of spectroscopic and gas chromatographic analyses. The inhibition was dose-dependent, and complete (more than 90%) inhibition of DNA polymerase alpha (pol. alpha), DNA polymerase beta (pol. beta) and HIV-reverse transcriptase type 1 (HIV-RT) was observed at concentrations of 5, 10, and 30 microM, respectively.

Chromatography, Gas↗
PubMed1998

[Identification of protein kinase C phosphorylation sites involved in desensitization of the histamine H1 receptor].

We studied whether direct phosphorylation plays a key role in protein kinase C-activating phorbol ester-mediated H1 receptor desensitization. Several potential protein kinase C-mediated phosphorylation sites were located in the third cytoplasmic loop form our cloning studies of H1 receptors. Ser396 and Ser398 were determined to be the phosphorylation sites by in vitro phosphorylation studies using synthetic peptides corresponding to the partial amino acid sequence of the third cytoplasmic loop. Mutant H1 receptors whose Ser396 or Ser398 were displaced by alanine were expressed in Chinese hamster ovary cells by site-directed mutagenesis. Characterization of these receptors revealed that Ser398, but not Ser396, was primarily responsible for protein kinase C-mediated H1 receptor desensitization.

Amino Acid Sequence↗
PubMed1998

Molecular cloning and sequence analysis of two endoinulinase genes from Aspergillus niger.

Two genomic DNAs encoding endoinulinase from Aspergillus niger 12 were cloned and sequenced. Open reading frames (ORFs) of the endoinulinase genes, inuA and inuB, both consisted of 1,548 nucleotides encoding 516 amino acids. It was suggested that the coding regions were not interrupted by introns. The ORFs differed from each other by 23 nucleotide substitutions or by eight amino acid replacements, indicating that the inuA and inuB genes arose by gene duplication. Each mature enzyme of 493 amino acids was preceded by a hydrophobic signal peptide of 23 amino acids. The enzymes contained two Cys residues and five potential sites for N-linked glycosylation. Partial amino acid sequences of the secreted enzyme suggested that it originated from the inuB gene product. The deduced amino acid sequences of the mature A. niger enzymes showed 73% identity with that of the Penicillium purpurogenum endoinulinase.

Amino Acid Sequence↗
PubMed1998

Hepatic veno-occlusive disease in a case of polymyositis associated with thrombotic thrombocytopenic purpura/hemolytic uremic syndrome.

A 50-year-old woman was treated with prednisolone for polymyositis. During the therapy, thrombotic thrombocytopenic purpura/hemolytic uremic syndrome (TTP/HUS) occurred. Neither plasma infusion nor plasma exchange could relieve the clinical manifestations of TTP/HUS. Moreover, massive ascites appeared and worsened her condition. She died approximately one year after the diagnosis of polymyositis. The autopsy revealed centri-lobular hepatic necrosis and nonthrombotic obliteration of hepatic small veins. The diagnosis of hepatic veno-occlusive disease (VOD) was made. It was suspected that common factors other than cytoreductive therapy had damaged the endothelium and caused TTP/HUS and VOD in a case of polymyositis.

Anti-Inflammatory Agents↗