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Biomedical subjects

S Kato

Publications and source records attributed to S Kato.

At least 1,369 records · Page 76Linked to original sources
PubMed1987

Respective roles of the microsomal ethanol oxidizing system and catalase in ethanol metabolism by deermice lacking alcohol dehydrogenase.

To evaluate the roles of MEOS (microsomal ethanol oxidizing system) and catalase in non-alcohol dehydrogenase (ADH) ethanol metabolism, MEOS and catalase activities in vitro and ethanol oxidation rates in hepatocytes from ADH-negative deermice were measured after treatment with catalase inhibitors and/or a stimulator of H2O2 generation. Inhibition of ethanol peroxidation by 3-amino-1,2,4-triazole (aminotriazole) was found to be greater than 85% up to 3 h and 80% at 6 h in liver homogenates. Urate (1 mM) which stimulates H2O2 production in living systems, increased ethanol oxidation fourfold in control but not in cells from aminotriazole-treated animals, documenting effective inhibition of catalase-mediated ethanol peroxidation by aminotriazole. While aminotriazole slightly depressed (15%) basal ethanol oxidation in hepatocytes, in vitro experiments showed a similar decrease in MEOS activity after aminotriazole pretreatment. Azide (0.1 mM), a potent inhibitor of catalase in vitro, also did not affect ethanol oxidation in control cells. By contrast, 1-butanol, a competitive inhibitor of MEOS, but neither a substrate nor an inhibitor of catalase, decreased ethanol oxidation rates in a dose-dependent manner. These results show that, in deermice lacking ADH, catalase plays little if any role in hepatic ethanol oxidation, and that MEOS mediates non-ADH metabolism.

1-Butanol↗
PubMed1987

Establishment and characterization of a T-lymphoblastoid cell line MDCC-MTB1 derived from chick lymphocytes infected in vitro with Marek's disease virus serotype 1.

Continuously proliferating T-lymphoblastoid cells, named MDCC-MTB1, were obtained by infection of chick embryo lymphocytes with Marek's disease virus serotype I (MDV1) in culture and subsequent cultivation in the presence of human interleukin 2 (IL-2). The MTB1 cells have now been growing well for at least 4 months with a doubling time of about 10 hr, irrespective of the presence of IL-2. The MTB1 cells show lymphoblastoid morphology, and carry T-lymphocyte marker surface antigens and a karyotype of female chick origin with several abnormal chromosomes. Southern blot hybridization showed that they contain about 10 virus genome equivalents/cell of almost the whole MDV genome. Infectious virus could not be rescued from MTB1 cells by co-cultivation of these with chick embryo fibroblasts. In addition, no virus particles were found in thin-sectioned MTB1 cells by electron microscopy. An immunofluorescence test with monoclonal antibody (MAb) to MDV-specific phosphorylated proteins showed that MTB1 cells expressed the MDV-specific antigen in the cytoplasm only after the cells had been treated with 5-iodo-2-deoxyuridine for 48 hr at 41 degrees C. MTB1 cells can form colonies in 0.33% soft agar, and can be transplanted into chicks by i.p. injection. Thus, continuously growing lymphoblastoid cells were obtained by in vitro infection of chick embryo lymphocytes with oncogenic MDV1 and cultivation of the cells in the presence of human IL-2 during the transformation step. These cells appear to show a similar phenotype to an MD lymphoma-derived cell line.

Animals↗
PubMed1987

Blockade of cholinergic receptors by an irreversible antagonist, propylbenzilylcholine mustard (PrBCM), in the rat cerebral cortex causes deficits in passive avoidance learning.

Studies were made on the effects of blockade of muscarinic acetylcholine (mACh) receptors in the rat cerebral cortex on learning and memory assessed by performance of a step-through passive avoidance task. Bilateral injection of propylbenzilylcholine mustard (PrBCM) into both the frontal and parietal cortex at doses of 2.25 X 4 to 22.5 X 4 micrograms decreased mACh receptors dose-dependently, as assessed by [3H]quinuclidinyl benzilate binding studies. When the training trial of a step-through passive avoidance task was performed 24 h after injection of 7.5 X 4 to 22.5 X 4 micrograms PrBCM into the frontal and parietal cortex, and then a retention test was made 24 h after the training trial, the treated rats showed shorter latencies than controls. In contrast, injection of PrBCM into the occipital cortex had no significant effect on performance in the test. These results confirm the notion that cholinergic neurotransmission in the cerebral cortex, especially the frontoparietal cortex, is important in learning and memory. The effects of injection of PrBCM (22.5 X 4 micrograms) into the frontoparietal cortex on 3 postulated phases of the learning and memory process (i.e. registration, retention and recall) were also examined. When PrBCM was injected 24 h before the training trial, no retention of the task was observed 14 days after the training trial. However, when PrBCM was injected 24 h after the training trial, retention of the task 14 days after the training trial was not affected. When PrBCM was injected 3-24 h after the initial training trial, the latencies in the retention test examined 24 h later were shorter than those of control rats.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1987

Sensitization of human tumor cells to homologous complement by vaccinia virus treatment.

Although cell membranes have potent inhibitors which protect the activation of complement on the self cell membranes, some viruses have been shown to activate complement via the alternative pathway on the virus-infected cells. Tumour cells have been made reactive to homologous complement following treatment with such viruses and became highly immunogenic to syngeneic host guinea pigs and mice. Vaccinia virus (VV) made murine tumour cells highly immunogenic thus generating complement activating capacity on the infected cells. Since it has been suggested that VV can make some human tumour cells immunogenic to the cancer patients, we examined VV to see if the virus also has the capacity to make human tumour cells reactive with homologous human complement. Our present results indicate that not only is this the case but ultraviolet-treated VV also has the same effect.

Complement Activation↗
PubMed1987

Partial ornithine transcarbamylase deficiency in females: diagnosis by an immunohistochemical method.

Females heterozygous for the X-linked urea cycle disorder, ornithine transcarbamylase (OTC) deficiency have a significant risk of developing hyperammonaemia. Diagnosis of this genetic defect in a proband is the essential starting point for family studies. By an immunohistochemical analysis of the liver specimens fixed in 10% formalin, we confirmed heterozygous status for OTC deficiency in two female patients, a 15-year-old girl and a 2-year-old girl, who died of hyperammonaemia. Since most affected males lack cross reactive materials (CRM), an immunochemical analysis should be useful for the diagnosis of most heterozygous females.

Adolescent↗
PubMed1987

Effects of bacterial endotoxin on the ciliary activity in the in vitro eustachian tube.

We have used a tissue culture technique and a photoelectric method to examine the direct effect of lipopolysaccharide (LPS) on the ciliary activity present in the eustachian tube. Since LPS possesses the major part of the biological activity of endotoxin, our results show clearly that LPS deteriorates the ciliary activity in a dose-response fashion: LPS does not deteriorate the ciliary activity up to 168 h if its concentration is 1 ng/ml or less; 10 ng/ml LPS can cause deterioration of the ciliary activity with extended exposure (more than 96 h); LPS can cause dysfunction of the cilia rather quickly if the concentration is 100 ng/ml or more. Our results show that the ciliary activity in the eustachian tube under clinical conditions can be affected by endotoxin.

Animals↗
PubMed1987

Ultracytochemical localization of alkaline phosphatase activity in endothelial cells in chronic relapsing experimental allergic encephalomyelitis.

To investigate the functions of endothelial cells (ECs) in chronic relapsing experimental allergic encephalomyelitis (EAE), we examined ECs ultracytochemically in various stages of EAE, in conjunction with the localization of alkaline phosphatase (AP) activity. We also studied the relation between the specific localization of AP activity and pathological features at each stage. Chronic relapsing EAE was induced in strain-13 guinea pigs by inoculation with homologous myelin. Controls were inoculated with complete Freund's adjuvant. The controls showed AP activity on the luminal and abluminal surfaces of the plasmalemma, and in pinocytic vesicles and vesicular pits. The localization of AP activity in the preclinical stage of EAE was similar to that in control animals. The initial inflammatory and actively demyelinating stage with perivascular cuffs of mononuclear cells showed AP-positive reactions on the abluminal surface of the plasmalemma, and in vesicles and pits, but not on the luminal surface in many ECs. In a later stage showing relatively old plaques with perivascular accumulation of debris-containing macrophages, AP activity continued to show localization similar to that seen in the initial stage, except for the presence of AP activity on some segments of the abluminal plasmalemma. Inactive lesions with marked perivascular fibrosis showed no AP reaction products. AP activity in unaffected areas showed the same localization as that in control animals throughout the various clinical stages of EAE. These findings suggest that AP activity decreased as the inflammatory demyelination in EAE progressed. The gradual disappearance of AP activity suggests development of functional impairment of ECs.

Alkaline Phosphatase↗
PubMed1987

Retinoic acid modulates attachment of mouse fibroblasts to laminin substrates.

The effect of retinoic acid treatment on cell attachment to plastic substrates precoated with fibronectin, gelatin, laminin, and type IV collagen was investigated. Both retinoic acid-treated and control cells attached efficiently to fibronectin or gelatin substrates without any significant difference. In contrast, retinoic acid-treated cells attached to laminin or type IV collagen substrates, while control cells showed little or no attachment. The minimal effective concentration of retinoic acid for pretreatment to yield a significant increase in the attachment assay was higher than 10(-8) M. The attachment of retinoic acid-treated cells to laminin substrates reached a maximum at 60 min, while that to type IV collagen substrates had a time lag and did not reach a maximum by 60 min. The effect of retinoic acid treatment reached a maximum at 2 days and was partly reversible. These results suggest that retinoic acid may increase NIH/3T3 cell adhesion through an effect on laminin receptors. Other mouse fibroblast lines, 3T3-Swiss, 3T6-Swiss, Balb/3T3, and Balb/3T12-3 (spontaneously transformed Balb/3T3), responded to retinoic acid treatment in a manner similar to that of NIH/3T3 cells. However, the virus-transformed Balb/3T3 lines, SV-T2 and M-MSV, showed significant attachment to laminin substrates without retinoic acid treatment, and retinoic acid did not affect or slightly decreased the cell attachment to laminin substrates.

Animals↗
PubMed1987

Paradoxical induction of dopaminergic cells following intravitreal injection of high doses of 6-hydroxydopamine in juvenile carp retina.

Histofluorescence studies were conducted on two groups of juvenile carp (body length, 12.7 and 6.6 cm on the average, respectively) during certain periods (3-11 months) of retinal growth, to evaluate the destructive effect of 6-hydroxydopamine on dopaminergic and indoleamine-accumulating cells. Within a certain range of doses (0.1-5.0 micrograms/eye) of the neurotoxin injected intravitreally, it was found to destroy both classes of cells in a dose-dependent manner: more cells disappeared with higher doses. However, a high dose (5-25 micrograms/eye) of the neurotoxin caused paradoxical events in the retina, inducing an appearance of clustered dopaminergic cells with various soma sizes and abnormally high regional density, disturbed laminar organization, and a facilitated growth rate at the retinal margin. A preliminary examination with [3H]thymidine labelling suggests that the high dose of 6-hydroxydopamine may cause severe damage to certain classes of cells including dopaminergic and indoleamine-accumulating cells, and that a metamorphic change of precursor cells (neuroblasts) in the outer nuclear layer is responsible for the induction of such abnormal dopaminergic cells as clusters.

Age Factors↗
PubMed1987

Localization of adenosine triphosphatase activity of the endothelia in chronic relapsing experimental allergic encephalomyelitis.

We used the method of ultracytochemical reaction for magnesium ion-dependent adenosine triphosphatase (Mg2+-ATPase) activity to study endothelial functions in various stages of chronic relapsing experimental allergic encephalomyelitis (EAE). In the endothelia of small vessels of the spinal cord of control guinea pigs, Mg2+-ATPase activity was cytochemically observed on the abluminal plasmalemma, and in pinocytotic vesicles and pits, but not on the luminal plasmalemma. The endothelia at the preclinical stage of EAE and in unaffected areas at various clinical stages, showed the same localization of Mg2+-ATPase activity as that in the control group. From the acute stage of active demyelination to the last stage of inactive lesions, Mg2+-ATPase activity in the endothelia of affected areas was localized on the luminal and abluminal surfaces of the plasmalemma, and in vesicles and pits. However, the intensity of the activity was lower than that in the control group. These findings suggest that, in chronic relapsing EAE, the endothelia of affected areas function differently from the endothelia of normal or unaffected areas.

Animals↗
PubMed1987

Why is Mg2+ necessary for specific cleavage of the terminal phosphoryl group of ATP?

The mechanism of specific cleavage of the terminal phosphoryl group in hydrolysis of ATP, and the role of Mg2+ in the hydrolysis were studied by ab initio molecular orbital calculations. The tetravalent anion of methyl triphosphate was used as a model of the ATP anion, and its electronic structures were determined as a function of the distance between Mg2+ and its beta-phosphoryl group. We found that the closer location of Mg2+ to the beta-phosphoryl group than to the alpha- or gamma-phosphoryl group was effective in weakening the P-O bond at which the cleavage of ATP catalyzed by most enzymes takes place. Moreover, the orbital coefficient of the frontier electron of P gamma, which is related to the nucleophilic reaction, was shown to increase greatly with increasing interaction between Mg2+ and the beta-phosphoryl group.

Adenosine Triphosphate↗
PubMed1987

Functional and morphological correlates of amacrine cells in carp retina.

Experiments were conducted on isolated retinas of adult carp (Cyprinus carpio) to investigate correlations between photoresponses and morphological features of amacrine cells. The fluorescence dye Lucifer Yellow CH was iontophoretically injected into single cells which had been characterized electrophysiologically. Photoresponses were classified into two main types (transient ON-OFF and sustained), which were further subgrouped into "fast" and "slow" ON-OFF types and into ON-center and OFF-center types, respectively. In the spectral response curve, all the types dealt with showed a maximum response at 621 nm, indicating that main input signals derive from red-sensitive cones. The cells marked by intracellular injection of the dye showed a great variety in morphology. Cells were classified into 8 subtypes, based on soma shape (fusiform or pyriform), dendritic field area (narrow, less than 0.3 mm2; medium, 0.3-0.8 mm2; wide, greater than 0.8 mm2), and dendritic stratification in the inner plexiform layer (restricted to sublamina a or b, or distributed diffusely). In certain cases a given response type was correlated with a specific morphological type, while receptive field size was not strictly correlated with dendritic field areas. Long and fine peripheral "axon-like" processes were found to arise from the primary dendrites of most fusiform cells. Dye-coupling was found among cells which appear to belong to the same cell category.

Action Potentials↗
PubMed1987

Plasma amino acid patterns in hepatocellular carcinoma.

Plasma amino acid levels were determined in 23 patients in comparison with 16 normal subjects and 17 patients with liver cirrhosis. Patients with hepatocellular carcinoma had elevated levels of the aromatic amino acids and lowered levels of the branched-chain amino acids, as seen in liver cirrhosis; however, they had lowered levels of alanine and glutamine as compared with normal subjects and with liver cirrhosis patients. Following treatment with intraarterial chemotherapy and/or transcatheter arterial embolization, plasma levels of alanine and glutamine recovered. These results suggest that the consumption of alanine and glutamine increase in hepatocellular carcinoma.

Adult↗
PubMed1987

Nonunion of the capitate.

A case of nonunion of the capitate of a 13-year-old girl is reported. Autogenous iliac bone grafting obtained union. At the 2-year follow-up, she had no complaints and had full motion of the wrist.

Adolescent↗
PubMed1987

Sequence of the cDNA encoding the laminin B1 chain reveals a multidomain protein containing cysteine-rich repeats.

Laminin is a basement membrane-specific glycoprotein (800 kDa) consisting of three chains: A, B1, and B2. Laminin has diverse biological functions, which include stimulating epithelial cell growth and differentiation. We have isolated two overlapping cDNA clones that span 5.9 kilobases and code for the entire B1 chain of mouse laminin. The nucleotide sequence of the clones reveals a 5358-base pair open reading frame that potentially codes for 1786 amino acids, including 20 amino acids of a presumptive signal peptide. Analysis of the deduced protein sequence predicts that the B1 chain has seven distinct domains that include cysteine-rich repeats, alpha-helical, and globular structures. Part of the cysteine-rich region is homologous to epidermal growth factor and other proteins that contain epidermal growth factor-like repeats.

Amino Acid Sequence↗
PubMed1987

Immunostaining on thin-layer chromatograms of oligosaccharides released from gangliosides by endoglycoceramidase.

A method for immobilizing oligosaccharides on a TLC plate for immunostaining has been developed. N-Glycolylneuraminic acid (NeuGc)-containing oligosaccharides derived from II3NeuGc-LacCer, IV3NeuGc-nLcOse4Cer, II3NeuGc-GgOse3Cer, and II3(NeuGc)2-LacCer by digestion with our newly isolated endoglycoceramidase (Ito, M. & Yamagata, T. (1986) J. Biol. Chem. 261, 14278-14282) and sialyllactose were chromatographed on polyamide 11 TLC or NH2-HPTLC plates, and covalently linked to the plates by reductive amination with sodium cyanoborohydride (NaBH3-CN). The immobilized oligosaccharides were detected by enzyme-immunostaining using NeuGc-specific chicken anti-NeuGc-LacCer and horseradish peroxidase-conjugated rabbit anti-chicken IgG. II3NeuGc-nLcOse4 showed the highest reactivity with the antibody, followed by II3NeuGc-GgOse3. As little as 0.8 nmol of the NeuGc-containing oligosaccharides was detected. The polyamide 11 TLC aluminum plate was found to be more suitable for the immunostaining than the NH2-HPTLC plate under the conditions used. For binding of the oligosaccharides to the NH2-HPTLC plate, reductive amination was found to be superior to the heating method reported earlier.

Animals↗
PubMed1987

Monoclonal antibodies to cowpox virus: polypeptide analysis of several major antigens.

Monoclonal antibodies directed against major antigens induced by cowpox virus (CPV) were produced. The specificities of these antibodies were established by immunoprecipitation, immunoblotting and several serological analyses, and from the cross-reactivities of these antibodies with cells infected with various other poxviruses, ectromelia virus (EV), vaccinia virus and Shope fibroma virus. The antibodies defined included ones reacting with each of the known major antigens of poxviruses, i.e. the common antigen of all poxviruses (probably NP antigen), the Orthopoxvirus-specific antigen (probably LS antigen), the haemagglutinin, the cell surface antigen, the common A-type inclusions in CPV and EV, and the antigen involved in neutralization.

Animals↗