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Biomedical subjects

H Sakai

Publications and source records attributed to H Sakai.

At least 901 records · Page 50Linked to original sources
PubMed1990

Characterization of hemoglobin-hydrolyzing acidic proteinases in human and rat neutrophils.

The nature and levels of hemoglobin (Hb)-hydrolyzing acidic proteinases including cathepsin D and cathepsin E, which were most active at pH 3.5-4.0, were enzymatically and immunochemically compared between human and rat neutrophils. By subcellular fractionation and immunoprecipitation with discriminative antibodies specific for each enzyme, cathepsin D was shown to be present in the granular content fraction of both human and rat neutrophils and to account for about 35% of the total Hb-hydrolyzing activity. Cathepsin E was observed mainly in the cytoplasmic fraction of rat neutrophils from peripheral blood and peritoneal exudates and accounted for about 65% of the total activity, but it was not detected in human blood neutrophils. Immunoelectron microscopy on rat neutrophils revealed that cathepsin D was exclusively confined to lysosomes, whereas cathepsin E was localized mainly in the cytoplasmic matrix and often in the perinuclear spaces and the rough endoplasmic reticulum. The non-cathepsin D activity in human neutrophils, which represented about 65% of the total activity, appeared to be due to a serine proteinase, since it was inhibited by diisopropyl fluorophosphate and phenylmethylsulfonyl fluoride and was not inhibited by agents specific for aspartic-, cysteine-, or metallo proteinases. The enzyme(s) responsible for this activity was largely associated with the granular membranes, and a half of it could be described as an integral membrane protein on the basis of phase separation with Triton X-114 at 35 degrees C. The levels of these Hb-hydrolases in gingival crevicular fluid from human chronic inflammatory periodontitis patients were examined in order to clarify their participation in the periodontal tissue breakdown.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1990

Preliminary study on specificity of IgA released from lymphocytes by EB virus transformation in patients with IgA nephropathy.

A study on the specificity of IgA in the supernatant of Epstein-Barr Virus (EBV) transformed lymphocytes obtained from patients with IgA nephropathy is described. Renal biopsy specimens were obtained from nine patients with IgA nephropathy and nine patients with other glomerular diseases. Mononuclear cells obtained from two patients with IgA nephropathy and two healthy adults were transformed with EBV and the supernatant of such transformed cell culture was applied to acid (pH 3.2)-treated renal sections obtained from the same and other patients with IgA nephropathy, as well as to those with other glomerular diseases. The sections were stained with FITC-labeled heavy chain-specific anti-human IgA antiserum and then examined with a fluorescent microscope. It was demonstrated that IgA in the supernatant specifically bound with the glomerular mesangial areas in patients with IgA nephropathy, while it did not bind with such areas in patients with other glomerular diseases. Although IgA in such samples bound with autologous renal tissues, about 50% bound with allogeneic renal specimens of IgA nephropathy. IgA in the supernatant of transformed lymphocytes from healthy adults was not bound with the glomerular mesangial areas of patients with IgA nephropathy and other glomerular diseases. It is concluded that IgA in the supernatant of lymphocytes by EB virus transformation is specific to the mesangial areas of IgA nephropathy and that some heterogeneity is seen among patients with this disease.

Adult↗
PubMed1990

Mutational activation of H-ras and K-ras genes is absent in N-nitroso-N-methylurea-induced liver tumors in rats.

We examined mutational activation of H- and K-ras genes in hyperplastic nodules and hepatocellular carcinomas induced by N-nitroso-N-methylurea or diethylnitrosamine using the polymerase chain reaction, followed by dot-blot hybridization. No mutational activation was detected in these hepatic lesions. The results indicate that low incidence of the activation of H- and K-ras genes in rat liver tumors is due to the organ specificity rather than the nature of the carcinogens used.

Animals↗
PubMed1990

Genotypic differentiation of intrahepatically transplanted hyperplastic nodule cells of analbuminemic and normal rat origin by polymerase chain reaction.

DNA fragments encompassing the region of the seven-base-pair deletion in the albumin gene, which is a characteristic abnormality of Nagase's analbuminemic rat (NAR), were amplified by polymerase chain reaction, and we could differentiate the genotypes of normal rat, homozygous NAR and heterozygous NAR electrophoretically. This genotyping method was applied to the differentiation of hyperplastic nodules on immunostained tissue sections in the intrahepatic transplantation model. When the hyperplastic nodule cells of normal rat were transplanted to the livers of homozygous NAR, the donor cells were effectively differentiated from the host cells by the genotype.

Albumins↗
PubMed1990

Fv-1 restriction of endogenous feline C-type RD114 virus genome phenotypically mixed with ecotropic murine leukemia viruses.

Endogenous feline leukemia RD114 virus genome rendered capable of infecting mouse cells by phenotypic mixing with an ecotropic murine leukemia virus (MuLV) exhibited the Fv-1 restriction pattern of the ecotropic murine virus. However, RD114 genomes phenotypically mixed with ecotropic MuLV showed one-hit dose-response kinetics, even when titrated with murine cells with the restricted Fv-1 phenotype.

AKR murine leukemia virus↗
PubMed1990

Epidermal adenylate cyclase system is regulated by diacylglycerol-protein kinase C signal, but not by calcium signal.

The breakdown of inositol phospholipids is an important transmembrane signalling system that is composed of two kinds of signals: the diacylglycerol-protein kinase C signal, and the inositol trisphosphate-Ca2+ signal. Using membrane-permeable diacylglycerol, I-oleoyl-2-acetylglycerol (OAG), and calcium ionophore, A-23187, the effects of these chemicals on the epidermal adenylate cyclase system were investigated. OAG increased forskolin- and cholera toxin-induced cyclic AMP accumulations, but receptor adenylate cyclase responses were markedly decreased by treatment with OAG. The effects of OAG were inhibited by the protein kinase C inhibitor, H-7. Calcium ionophore, A-23187, had no effect on the epidermal adenylate cyclase responses. Combinations of OAG and A-23187 (as well as the calcium chelator, EGTA), showed that the action of OAG was mostly unaffected by the modulation of intracellular and extracellular Ca2+ concentrations. The results suggest that among the signals triggered by the breakdown of inositol phospholipids, only diacylglycerol-protein kinase C signal is involved in the regulation of the epidermal adenylate cyclase system.

Adenylyl Cyclases↗
PubMed1990

Immunohistochemical localization of c-myc oncogene product and EGF receptor in oral squamous cell carcinoma.

Subcellular distribution of c-myc oncogene product and EGF receptor in oral squamous cell carcinomas was examined by using immunohistochemical method. Immunohistochemy for c-myc oncogene showed three staining patterns. Reactive products were demonstrable in the nucleus, in the perinuclear cytoplasm with granular appearance and in the entire cytoplasm. Concomitant stainings of each reactive pattern were observed. Occasionally, the reactive product was strongly deposited on the chromatin under mitotic phase. EGF receptor positive cases were found in only 4 of 28 cases. Though reactive products were usually found in the cytoplasm, the cell surface staining was detected in the only one case. In this case, cells under mitotic phase were strongly stained. The fact that the strong staining both of c-myc and EGF receptor in cells under mitotic phase suggested the close relation between the expression of these genes and the proliferation of carcinoma cells.

Antibodies, Monoclonal↗
PubMed1990

Construction and characterization of an infectious DNA clone and of mutants of simian immunodeficiency virus isolated from the African green monkey.

We constructed a full-length molecular clone of simian immunodeficiency virus from an African green monkey. Upon transfection, this clone directed the production of virus particles cytopathic and infectious to human CD4+ leukemia cell lines. Mutations were introduced by recombinant DNA techniques into eight open reading frames of simian immunodeficiency virus from the African green monkey thus far identified. The phenotypes of mutant viruses, i.e., infectivity, cytopathogenicity, transactivation of gene expression controlled by a long terminal repeat, and viral RNA and protein syntheses, were examined by transfection and infection experiments. Three structural (gag, pol, and env) and two regulatory (tat and rev) gene mutants were not infectious, whereas vif, vpx, and nef were dispensable for infectivity and mutant viruses were highly cytopathic. In transient transfection assays, a rev mutant produced mainly small mRNA species and no detectable virus protein and particles. The transactivation potential of a tat mutant was about 10-fold less than that of wild-type DNA, generating small amounts of virus.

Animals↗
PubMed1990

Functional comparison of transactivation by human retrovirus rev and rex genes.

The effect of rev-responsive element deletion on human immunodeficiency virus type 1 (HIV-1) and type 2 (HIV-2) gene expression was examined. The phenotypes of HIV-1 and HIV-2 provirus DNAs lacking the rev-responsive element, as determined by transfection experiments, were indistinguishable from those of virus DNAs carrying rev gene mutations. By using rev-response elements derived from these two viruses, we developed two monitoring systems to evaluate the functionality of HIV-1 rev, HIV-2 rev, and human T-lymphotropic virus type I rex. In both systems, HIV-1 rev and human T-lymphotropic virus type I rex transactivated HIV-2 very efficiently. On the contrary, HIV-2 rev and human T-lymphotropic virus type I rex were poor activators of HIV-1. No functional replacement of rex by HIV-2 rev was observed.

Blotting, Northern↗
PubMed1990

Generation and characterization of infectious chimeric clones between human immunodeficiency virus type 1 and simian immunodeficiency virus from an African green monkey.

A series of chimeric clones of human immunodeficiency virus type 1 and simian immunodeficiency virus isolated from an African green monkey was constructed in vitro. In transient transfection experiments, all clones produced virion-associated reverse transcriptase, gag proteins, and env proteins. Eight out of 10 chimeric viruses clearly grew in the human CD4+ cell line C8166. Susceptibility of other CD4+ cell lines, MT-4, A3.01, and Molt4 clone 8, to infection with these viruses was also demonstrated.

Animals↗
PubMed1990

Mutational analysis of the human immunodeficiency virus type 2 (HIV-2) genome in relation to HIV-1 and simian immunodeficiency virus SIV (AGM).

We constructed an infectious molecular clone of the human immunodeficiency virus type 2 (HIV-2) and generated nine frameshift mutants corresponding to nine open reading frames identified so far. Three structural (gag, pol, env) and two regulative (tat, rev) gene mutants were not infectious, whereas vif, vpx, vpr, and nef genes were dispensable for infectivity. All of the mutants except env and rev were cytopathic in CD4+ human leukemia cells. In transfection assays, the expression of HIV-2 long terminal repeat was activated by infectious clones of HIV-1, HIV-2, and simian immunodeficiency virus from African green monkey but not by the tat mutants. However, an HIV-2 tat mutant could produce small amounts of virus proteins and particles in contrast to a rev mutant, which directed no detectable synthesis of virus proteins and virions.

Blotting, Northern↗
PubMed1990

Complementation of the rev gene mutation among human and simian lentiviruses.

The functional exchangeability of the rev gene was assessed in transient transfection experiments by using in vitro-constructed rev and gag mutants of the following three primate lentiviruses: human immunodeficiency virus type 1 (HIV-1), HIV-2, and simian immunodeficiency virus from the African green monkey (SIV AGM). Cotransfection into SW480 cells of the rev and gag mutants derived from the DNA of each infectious virus resulted in the generation of progeny particles as determined by reverse transcriptase assay. rev gene mutants of HIV-2 and SIV AGM were also complemented by all gag mutants derived from the three viruses. In contrast, no evidence of complementation was obtained following cotransfection of the HIV-1 rev mutant and the gag mutant of HIV-2 or SIV AGM.

Amino Acid Sequence↗
PubMed1990

Cathepsins D and E in normal, metaplastic, dysplastic, and carcinomatous gastric tissue: an immunohistochemical study.

Immunohistochemical distributions of cathepsins D and E were determined in normal mucosa, metaplastic, dysplastic, and cancerous lesions of the human stomach. Cathepsins D and E were localised in the foveolar epithelium and parietal cells of the normal gastric mucosa, but their intracytoplasmic distributions were different - cathepsin E distribution was even and diffuse in the cytoplasm while cathepsin D was found in coarse intracytoplasmic granules. Chronic inflammation and ulcer did not influence the distribution of these enzymes. No positive staining was obtained in the incomplete type of intestinal metaplasia, dysplasia, and well differentiated adenocarcinoma. Tumour cells of signet ring cell carcinoma and poorly differentiated adenocarcinoma cells, however, gave strong and diffuse stainings for cathepsins D and E in the cytoplasm. The results suggest that the distribution of cathepsins D and E is related to each specialised function of the foveolar epithelium and the parietal cells, and that their disappearance is associated with development of well differentiated adenocarcinoma from intestinal metaplasia.

Adenocarcinoma↗
PubMed1990

High dose intact-immunoglobulin treatment for an HIV-infected asymptomatic carrier with hemophilia.

Intravenous administration of a high dose of intact-immunoglobulin to a human immunodeficiency virus (HIV) infected patient with hemophilia A, whose total lymphocyte and CD4 positive lymphocyte counts showed a decreasing tendency, resulted in a gradual rise in these cell counts. The results were quite reproducible on another occasions. Therefore, intravenous administration of gammaglobulin (IVGG) was thought to be effective for preventing further deterioration of cellular immunity and progression from asymptomatic carrier (AC) to AIDS related complex (ARC)/AIDS in hemophilia patients.

Adult↗
PubMed1990

The effect of OP 2507, a stable analogue of prostacyclin, on Hep G2 exposed to hypoxia.

We developed a model for screening drugs to reduce ischemic liver damage using Hep G2, a hepatoblastoma cell line, and examined the effect of OP 2507, a stable analogue of prostacyclin, on hypoxic cell damage. Hypoxic exposure of the cells was done for 16 hr in an air-tight chamber which was placed inside an incubator and was purged with 5% CO2/95% N2. Adding OP 2507 (0.01-10 ng/ml) to the incubation medium during hypoxic exposure reduced mitochondrial damage estimated by MTT-reducing activity, while it failed to inhibit lactate accumulation in the medium. OP 2507 seems to be a good candidate for improving the preservation of liver allografts.

Animals↗
PubMed1990

Effects of glycyrrhizin (SNMC: Stronger Neo-Minophagen C) in hemophilia patients with HIV-1 infection.

Forty-two hemophiliacs with HIV infection were treated with high-dose glycyrrhizin, Stronger Neo-Minophagen C (SNMC). The dose was 100-200 ml of SNMC in 21 patients and 400-800 ml in the other 21. The patients were divided into an asymptomatic carrier (AC) group and AIDS related-complex (ARC)/AIDS group. SNMC was administered intravenously daily for the first 3 weeks, and every second day for the following 8 weeks to the 42 HIV-infected hemophilia patients, in accordance with the protocol proposed by the Japanese National Research Committee. The CD4/CD8 ratio and CD4 positive lymphocyte counts did not change during the treatment period. However, significant improvement was noted in some cases. A slight increase in mitogenic responsiveness to phytohemagglutinin, Concanavalin A and pokeweed mitogen was noted in most patients of both groups, especially significant improvement was seen in the AC group administered over 400 ml of SNMC. Furthermore, complete improvement was noted in liver dysfunction, which has been thought to be one of the major problems for hemophiliacs treated with blood products. Thus, prophylactic administration of high-dose SNMC to HIV positive hemophiliacs who have impaired immunological ability and liver dysfunction was considered to be effective in preventing the development from AC/ARC to AIDS.

AIDS-Related Complex↗
PubMed1990

Holocord astrocytoma--case report.

A rare case of intramedullary holocord astrocytoma extending from the medulla oblongata to the conus medullaris is reported. A 27-year-old male who had been suffering from nuchalgia for a few years was admitted to our department because of lumbago and gait disturbance. Neurological examination revealed sensory disturbances in various locations, weakness of the right lower extremity, mild swallowing disturbance, and bowel and bladder difficulties. Magnetic resonance (MR) images and myelograms showed a long cystic lesion extending from the medulla oblongata to the thoracolumbar spinal cord. Gadolinium-diethylenetriaminepenta-acetic acid (Gd-DTPA)-enhanced images detected a solid tumor located at the Th6-7 level. Two syrinx-subarachnoid shunts were placed at the upper cervical and Th12 levels. The solid neoplasm at the Th7 level was partially resected and histologically diagnosed as astrocytoma. Differentiation between cystic lesions and solid masses in the spinal cord is difficult. The usefulness of Gd-DTPA-enhanced MR imaging in the diagnosis of holocord tumor and the pathogenesis of secondary syringomyelia are discussed.

Adult↗