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Biomedical subjects

A Hirata

Publications and source records attributed to A Hirata.

At least 181 records · Page 10Linked to original sources
PubMed1993

Organ culture with proinflammatory cytokines reproduces impairment of the beta-adrenoceptor-mediated relaxation in tracheas of a guinea pig antigen model.

The challenge of previously sensitized guinea pigs with aerosolized ovalbumin resulted in impairment of the beta-adrenoceptor-mediated relaxation as measured by the in vitro isometric assay of tracheas preconstricted with endothelin-1 or carbamylcholine. Numbers and affinities of beta-adrenoceptors in lung membranes of these animals were not altered under these conditions, although the antigen challenge caused an inflammatory response, as evident from the accumulation of inflammatory cells in the bronchoalveolar lavage fluids. In order to investigate the pathophysiologic role of inflammation in hyperreactive airways, isolated guinea pig tracheas were cultured with proinflammatory cytokines such as human recombinant tumor necrosis factor-alpha (TNF-alpha), interleukin-1 beta (IL-1 beta), or interleukin-2 (IL-2). None of these cytokines affected the contractile response of tracheas to carbamylcholine. After preconstriction with carbamylcholine, the TNF-alpha- and IL-1 beta-pretreated tissues produced a significant reduction in the maximal relaxation induced by isoproterenol, whereas the IL-2 pretreatment had no effect. The reduction of the isoproterenol-mediated relaxation by the IL-1 beta treatment was time and dose dependent. Our present observations suggest that in vitro incubation of naive tracheas with proinflammatory cytokines is able to reproduce apparent beta-adrenoceptor impairment as seen in the airways of antigen-challenged guinea pigs of asthma model.

Animals↗
PubMed1993

Morphological changes and reorganization of actinfilaments in human myeloid leukemia cells induced by a novel protein phosphatase inhibitor, tautomycin.

A protein phosphatase inhibitor, tautomycin induces blebs on the surface of human myeloid leukemia K562 cells within 10 min. In this paper we examined the cytoskeleton of tautomycin-treated cells. In the presence of tautomycin, cells with blebs turned into segmented forms with smooth surfaces after 15 min and into smooth round shapes without microprotuberance after 60 min. Observation with fluorescence microscopy showed that F-actin detached from the plasma membrane at the site of the blebs. Further treatment with tautomycin induced the accumulation of F-actin at the segmentation centers. Under electron microscopy, an electron dense ring-structure was detected at the segmentation center. Tautomycin did not induce major changes of the microtubule network although F-actin accumulated near the microtubule organizing center. The amount of F-actin increased in tautomycin-treated cells. These results indicate that the morphological changes are induced by reorganization of actinfilaments.

Actin Cytoskeleton↗
PubMed1993

Detection of immunoreactive schizophyllan by solid-phase enzyme-linked immunosorbent assay.

In order to detect immunoreactive schizophyllan (SPG), one of the beta-1,3-glucans in solution, a murine anti-schizophyllan monoclonal antibody, SPG1-HS, was used as a primary antibody for solid-phase enzyme-linked immunosorbent assay (ELISA). Polysaccharide-bovine serum albumin (BSA), and polysaccharide-bovine hemoglobin (Hb) conjugate were prepared as an antigen. The absorbance at 490 nm in ELISA was directly proportional to the SPG concentration in SPG-BSA or SPG-Hb conjugates, allowing the accurate measurement of SPG at concentrations of more than 1.0 microgram/ml. Also, this ELISA detected SPG in SPG-BSA and SPG-Hb conjugates in human serum in a similar manner. These results suggest that this ELISA is applicable for the determination of SPG concentration in SPG-BSA and SPG-Hb conjugates in human tissue and blood.

Animals↗
PubMed1993

Large-scale production and purification of an Erwinia ananas ice nucleation protein and evaluation of its ice nucleation activity.

The ice nucleation-active protein of Erwinia ananas IN-10 (inaA protein) was over-expressed as inclusion bodies in Escherichia coli in a yield of 15.3 mg of inaA protein from 60 mg of bacterial cells on a dry-matter basis. The inaA protein was purified from the inclusion bodies by solubilization with detergents to obtain a protein preparation free from sugar and lipid. This preparation had a distinct ice nucleation activity, indicating that the inaA protein per se is able to act as a nucleus.

Amino Acid Sequence↗
PubMed1993

[A new leak test of anesthetic machine].

A case of the inspired PCO2 increase secondary to the malfunction of expiratory valve due to a defected edge of creator is presented. In this case, we could not detect the malfunction of expiratory valve using the preanesthetic routine leak test but found it by observing the expiratory phase of the capnometric curve. Therefore, we devised a new leak test for checking the malfunction of inspiratory and expiratory valves. This test is simple and effective. The test consists of the following procedures.: 1. Connecting yokes to the oxygen piping system. 2. Connecting the breathing bag. 3. Occluding the inspiratory terminal. Closing the semiclosed valve completely. 4. Flushing the O2 gas and increasing the pressure of breathing circuit to 30 cmH2O. 5. Monitoring the pressure gauge of the anesthesia system. If the function of valves is normal, the system pressure decreases slowly. If either of the valves works wrong, it decreases rapidly. We checked anesthesia machines in our facilities using the new leak test, and found some cases of the expiratory valve malfunctions.

Adenocarcinoma↗
PubMed1993

High serum soluble interleukin-2 receptor concentrations in elderly individuals and smokers.

The effects of sex, age, and smoking on the serum concentrations of soluble interleukin-2 receptor (sIL-2R) were investigated in 83 healthy subjects. No sex-related difference was found. The correlation between age and the serum sIL-2R concentration was weak, but significant, in the nonsmokers (r = 0.30, n = 50, p < 0.05). The serum sIL-2R concentration was significantly higher in smokers than in nonsmokers (41.0 +/- 2.8 pM (mean +/- SEM), n = 33, vs. 31.9 +/- 1.0, n = 50, p < 0.005). These results suggest that age and smoking habits should be taken into consideration when interpreting the serum sIL-2R concentration, although the mechanism by which sIL-2R concentrations are altered remains unknown at present.

Adult↗
PubMed1992

Light-induced oxidation of iron atoms in a photosensitive nitrile hydratase.

The photoactivation process of a photosensitive nitrile hydratase (NHase) from Rhodococcus sp. N-771 has been investigated by 57Fe Mössbauer spectroscopy and magnetic susceptibility measurements in order to clarify the behavior of iron atoms in the enzyme. Mössbauer spectra of inactive NHase gave two symmetric-doublet components indicating the presence of two iron species, while that of the active NHase gave a single symmetric doublet indicating the presence of a single iron species. Magnetic susceptibility measurements of the inactive and active HNase both showed small effective magnetic moments. These results led us to conclude that one of the two iron atoms incorporated in the NHase is oxidized during photoactivation, namely from a low spin ferrous to a low spin ferric state. This is the first observation of an intramolecular photooxidation phenomena involving iron in a single protein molecule.

Enzyme Activation↗
PubMed1992

Electron microscopic examination of sporulation-deficient mutants of the fission yeast Schizosaccharomyces pombe.

A homothallic haploid strain of the fission yeast Schizosaccharomyces pombe initiates sexual reproduction (mating, meiosis and sporulation) in nitrogen-free sporulation medium. Cellular fine structures of eleven sporulation-deficient mutants (spo2, spo3, spo4, spo5, spo6, spo13, spo14, spo15, spo18, spo19 and spo20) of S. pombe in sporulation medium were examined by serial section-electron microscopy. The striking features of these spo mutants were: 1) the disappearance of the spindle pole bodies (SPBs) after the second meiotic division, and 2) the accumulation of unorganized structures. Based on histochemical staining, these structures were presumably unorganized spore wall precursors. In some mutants (spo3, spo5, spo6, spo19 and spo20), diploid zygotes contained four spore-like bodies which had walls similar to complete spore walls but failed to enclose any nuclei. After completion of the second meiotic division the nuclei were abnormally distributed in zygotic diploid cells. In the spo5, spo13, spo14, spo15 and spo19 mutants, the nuclei remained attached to each other. In spo5 and spo19, the inner membrane of the nuclear envelope was separated, but its outer membrane was shared by two sister nuclei. These observations suggest that the spo+ gene products play important roles in spatial and temporal organization of cellular structures during ascospore development.

Genes, Fungal↗
PubMed1992

Mutations in yeast calmodulin cause defects in spindle pole body functions and nuclear integrity.

Yeast calmodulin (CaM) is required for the progression of nuclear division (Ohya, Y. and Y. Anraku. 1989. Curr. Genet. 15:113-120), although the precise mechanism and physiological role of CaM in this process are unclear. In this paper we have characterized the phenotype caused by a temperature-sensitive lethal mutation (cmdl-101) in the yeast CaM. The cmdl-101 mutation expresses a carboxyl-terminal half of the yeast CaM (Met72-Cys147) under the control of an inducible GAL1 promoter. Incubation of the cmdl-101 cells at a nonpermissive temperature causes a severe defect in chromosome segregation. The rate of chromosome loss in the cmdl-101 mutant is higher than wild-type cell even at permissive temperature. The primary visible defect observed by immunofluorescence and electron microscopic analyses is that the organization of spindle microtubules is abnormal in the cmdl-101 cells grown at nonpermissive temperature. Majority of budded cells arrested at the high temperature contain only one spindle pole body (SPB), which forms monopolar spindle, whereas the budded cells of the same strain incubated at permissive temperature all contain two SPBs. Using the freeze-substituted fixation method, we found that the integrity of the nuclear morphology of the cmdl-101 mutant cell is significantly disturbed. The nucleus in wild-type cells is round with smooth contours of nuclear envelope. However, the nuclear envelope in the mutant cells appears to be very flexible and forms irregular projections and invaginations that are never seen in wild-type cells. The deformation of the nuclear becomes much more severe as the incubation at nonpermissive temperature continues. The single SPB frequently localizes on the projections or the invaginations of the nuclear envelope. These observations suggest that CaM is required for the functions of SPB and spindle, and the integrity of nucleus.

Calmodulin↗
PubMed1992

Preparation and characterization of a murine monoclonal antibody (MDR3M) reactive with mdr3 gene product.

A murine monoclonal antibody (MDR3M) (isotype: IgM) reactive with mdr3 gene product was generated by immunizing mice with mdr3-specific peptide (H2N-12WRPTSAEGDFELGISSKQKRKKTKTVKMI41G-COOH) and hybridizing the primed mouse splenic B cells with X63-Ag8,6.5.3 mouse plasmacytoma cells. MDR3M did not cross-react with mdr1 gene product. This monoclonal antibody may be useful for analyzing the role of mdr3 gene product in cells and tissues.

Amino Acid Sequence↗
PubMed1992

Autoradiographic studies of aged primate macular retinal pigment epithelium.

The authors used 35S-sulfate and 3H-proline to trace labeled molecules in autoradiograms of aged monkey and human macular retina to detect the synthesis of extracellular matrix (ECM) components by retinal pigment epithelial (RPE) cells. Quantitative analysis of silver grains 6 hr and 3 d after intravitreal injection of 35S-sulfate in the monkey showed that secretion from the basal pole of the RPE occurs at a slower rate than from the apical pole. In vitro incubation of human maculas produced poor autoradiographs with 35S-sulfate. Good autoradiographs were obtained using 3H-proline. Human macular RPE showed uneven labeling, but densely labeled cells did not correlate with sites of basal linear deposits, ECM though to be basement membrane material, and a hallmark of age-related maculopathy. The time course of labeling in adult primate tissue showed a fairly high turnover rate for these molecules. Scant labeling of ECM at drusen sites and no labeling in basal linear deposits suggested that either (1) these structures have a slow turnover or (2) their components contain scant sulfate and proline. Alternatively, faulty degradative processes rather than enhanced synthesis may account for the accumulation of abnormal ECM at the RPE-Bruch's membrane interface in aged maculas.

Adult↗
PubMed1991

Crystallization of a photosensitive nitrile hydratase from Rhodococcus sp. N-771.

A photosensitive nitrile hydratase from Rhodococcus sp. N-771 has been crystallized in two different crystal forms in its inactive form. One crystal form belongs to an orthorhombic space group P2(1)2(1)2 with unit cell dimensions of a = 117.4 A, b = 145.7 A and c = 52.1 A, and the other form belongs to a hexagonal space group P6(3)22 with unit cell dimensions of a = 110.2 A and c = 412.1 A.

Crystallization↗
PubMed1991

Sympodiomycopsis: a new yeast-like anamorph genus with basidiomycetous nature from orchid nectar.

A description is provided for a new anamorph genus Sympodiomycopsis (Hyphomycetes), which is neither ballistosporogenous nor sterigmatosporogenous. The genus is typified by S. paphiopedili sp. nov. and accommodates one species which was isolated from nectar of Paphiopedilum primurinum in Japan. Phenotypically, the genus shows some similarity to Sympodiomyces because of the presence of a yeast morph with sympodial conidiogenous cell proliferation, but it is distinguished from that genus morphologically by a yeast morph with the enteroblastic-annellidic conidiogenesis and the conspicuous development of a hyphal morph with holoblastic-sympodial conidiogenous cells, and chemotaxonomically by the ubiquinone system Q-10 and 10% difference in the guanine plus cytosine (G + C) content of the nuclear DNA. Phylogenetically, the type of cell wall and septal pore ultrastructure, and the primary biochemical and chemotaxonomic characters of S. paphiopedili indicate a basidiomycetous affinity.

Basidiomycota↗
PubMed1991

Integral laser photodynamic treatment of refractory multifocal bladder tumors.

Integral photodynamic therapy with hematoporphyrin derivative was performed on 35 patients who had resistant transitional cell carcinoma of the bladder, mainly carcinoma in situ. The light source was an argon ion pumped dye laser (wavelength 630 nm.) using rhodamine B. Two types of laser light scattering diffuser developed at our department were used: a motor driven laser light scattering diffuser with computer regulation, and an endoscope modified light scattering diffuser tipped with a small quartz bulb containing a lipid nutritious solution as the scattering medium. The total energy density used was 10 to 30 J./cm.2. Of the 35 patients 24 (68.6%) achieved a complete response and 5 (14.3%) a partial response at 3 months. In 10 of the 24 patients there was no recurrence with an average tumor-free interval of 20.9 +/- 16.7 months, ranging from 5 to 60 months. Bladder capacity was decreased to approximately 150 ml. for 3 months after the integral photodynamic therapy without any evidence of hydronephrosis on excretory urograms, except for 2 patients who had a contracted bladder before photodynamic therapy. Integral photodynamic therapy may prove to be useful for the treatment of carcinoma in situ of the bladder.

Adult↗
PubMed1991

A cytoskeleton-related gene, uso1, is required for intracellular protein transport in Saccharomyces cerevisiae.

The Saccharomyces cerevisiae mutant strains blocked in the protein secretion pathway are not able to induce sexual aggregation. We have utilized the defect of aggregation to concentrate the secretion-deficient cells and identified a new gene which functions in the process of intracellular protein transport. The new mutant, uso1, is temperature sensitive for growth and protein secretion. At the restrictive temperature (37 degrees C), uso1 mutant accumulated the core-glycosylated precursor form of the exported protein invertase in the cells. Ultrastructural study of the mutant fixed by the freeze-substitution method revealed expansion of the nuclear envelope lumen and accumulation of the ER at the restrictive temperature. Abnormally oriented bundles of microtubules were often found in the nucleus. The USO1 gene was cloned by complementation of the uso1 temperature-sensitive growth defect. DNA sequence analysis revealed a hydrophilic protein of 1790 amino acids with a COOH-terminal 1,100-amino acid-long alpha-helical structure characteristic of the coiled-coil rod region of the cytoskeleton-related proteins. These observations suggest that Uso1 protein plays a role as a cytoskeletal component in the protein transport from the ER to the later secretory compartments.

Amino Acid Sequence↗