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Biomedical subjects

Y Ito

Publications and source records attributed to Y Ito.

At least 19 recordsLinked to original sources
PubMed1992

Detection of antibody to hepatitis C E2/NS1 protein in patients with type C hepatitis.

Putative E2/NS1 sequence of hepatitis C virus was expressed in E. coli as a fusion protein with maltose binding protein. Approximately 80 kDa protein was obtained containing 38 kDa E2/NS1 protein. The antibody to this protein was detectable in the same serum from which the sequence was amplified. It was also detectable in none of 7 acute hepatitis, in 2 of 12 chronic persistent hepatitis, in 3 of 25 chronic active hepatitis, and in 2 of 4 cirrhosis. It was detectable in none of 10 normal subjects. In 3 cases who were positive for the antibody before the interferon treatment, it became undetectable after the treatment. Thus, it seems that the antibody is not a neutralizing antibody and is related to active viral replication.

Base Sequence↗
PubMed1992

Age-related increase in systolic fraction of pulmonary vein flow velocity-time integral from transesophageal Doppler echocardiography in subjects without cardiac disease.

The pulmonary vein flow velocity-time profile would be equivalent to the pulmonary vein flow volume-time profile, provided that the cross-sectional area of the pulmonary vein remains unchanged during 1 cardiac cycle. The systolic fraction of the pulmonary vein flow velocity-time integral, a ratio of velocity-time integral of the S wave to the sum of velocity-time integrals of the S and D waves, represents the ratio of left atrial storage volume to left ventricular stroke volume. This systolic fraction may help early filling of the left ventricle through an appropriate storage of blood and generation of driving pressure in the left atrium. Because early filling of the left ventricle is progressively impaired with age, it was hypothesized that this systolic fraction is increased with age. Forty-four noncardiac surgical patients (age range 17 to 70 years) who underwent transesophageal Doppler echocardiography under general anesthesia were studied, and left upper pulmonary vein flow and mitral inflow velocities were recorded. The ratio of peak velocity of the E wave to that of the A wave of mitral inflow velocity-time profile (y) decreased with age (y = -0.0245 x age + 2.41; r = -0.672, p < 0.01). Systolic fraction (y) increased with age (y = 0.00373 x age + 0.514; r = 0.656, p < 0.01). The age-related increase in the systolic fraction of pulmonary vein flow velocity-time integral may account for the compensation for impaired early filling of the left ventricle in elderly patients.

Adolescent↗
PubMed1992

Unusual diffuse liver fibrosis accompanying transient myeloproliferative disorder in Down's syndrome: a report of four autopsy cases and proposal of a hypothesis.

Transient myeloproliferative disorder (TMD), an acute leukemia-like disorder in neonates with Down's syndrome, is characterized by spontaneous regression of abnormal blast growth. Because proliferating blasts frequently express phenotypes of megakaryocytic lineage and, as a result, this disorder resembles acute megakaryoblastic leukemia (AMKL), it would be of interest to determine whether myelofibrosis, a common complication of AMKL, is also present in TMD. Pathologic observations of four autopsy cases of TMD showed that myelofibrosis was not present in any of them, whereas intralobular diffuse liver fibrosis was present in all of them. Laboratory data of four additional cases showed hepatic dysfunction in all of them, suggesting a close association between hepatic lesions and TMD. From these results, we propose a hypothesis that the abnormal blasts with megakaryocytic properties in TMD originate from the fetal liver and cause liver fibrosis, as AMKL cells are thought to cause myelofibrosis by producing collagen-stimulating cytokines in the bone marrow. This hypothesis also seems to explain some other unique aspects of TMD.

Autopsy↗
PubMed1992

Complementary use of counter-current chromatography and preparative reversed-phase high-performance liquid chromatography in the separation of a synthetic mixture of brominated tetrachlorofluoresceins.

A synthetically prepared mixture of brominated 4,5,6,7-tetrachlorofloresceins was separated by a combination of preparative reversed-phase high-performance liquid chromatography and high-speed counter-current chromatography. Two new lower-brominated subsidiary colors of D&C Red Nos. 27 and 28 (phloxine B), 4',5'-dibromo-4, 5,6,7-tetrachlorofluorescein and 2',4',5'-tribromo-4,5,6, 7-tetrachlorofluorescein, were isolated and characterized by 1H NMR and chemical ionization mass spectrometry.

Chromatography, High Pressure Liquid↗
PubMed1992

Purification and partial identification of bone-inducing protein from a murine osteosarcoma.

A highly purified fraction with bone-inducing potential was obtained from a murine osteosarcoma using initial fractionation, gel filtration on Sephacryl S-200, and cation-exchange, hydroxyapatite and reverse-phase h.p.l.c. Protein sequencing of the sample derived from this active fraction revealed the N-terminal amino acid sequence to be Ala-Ala-Leu-Arg-Pro-Leu-Val-Lys-Pro, which is identical to the N-terminal sequence of mouse, human and rat ribosomal protein L32, except for an additional methionine residue at the N-terminus of the three latter proteins. Amino acid analysis of the sample also showed its similarity to L32. Two lines of evidence using an antibody specific for the above peptide strongly suggest that this L32-related protein from a murine osteosarcoma has the potential to induce ectopic bone formation. First, the protein specifically detected by the antibody co-distributes with the bone-inducing active fraction. Secondly, a highly purified sample obtained using the antibody was shown to induce the formation of bone with active haematopoiesis.

Amino Acid Sequence↗
PubMed1992

Potassium channels cloned from neuroblastoma cells display slowly inactivating outward currents in Xenopus oocytes.

Messenger RNAs (mRNAs) specific for NGK1 and NGK2 potassium channels were synthesized from complementary DNAs (cDNAs) that had been cloned from mouse neuroblastoma x rat glioma hybrid NG108-15 cells. Outward pottasium currents were evoked by 5 s depolarizing voltage commands in Xenopus oocytes injected with NGK1- or NGK2-specific mRNAs. The NGK1 or NGK2 currents showed different activation and inactivation kinetics, and different pharmacological sensitivities. The threshold potential for activation of the NGK2 current (-14 mV) was more positive than that for the NGK1 (-36 mV). The NGK2 current showed faster inactivation during a 5 s depolarizing pulse than did the NGK1 current. Inactivation was best fit by time constants of 0.37, 1.5 and 19 s for the NGK2 current and 4.4 and 19 s for NGK1. Extracellularly applied tetraethylammonium chloride (TEA) was 1000 times more potent on the NGK2 current than the NGK1 current. Furthermore we examined outward current following co-injection of an equal amount of mRNAs for NGK1 and NGK2. The timecourse of inactivation differed from either alone or from a simple sum of the two individual currents. TEA sensitivity could not be explained by summation of the two homomultimeric channels. These findings suggest that both NGK1 and NGK2 proteins assemble to form heteromultimeric K+ channels in addition to homomultimeric K+ channels. NGK2 channels and the heteromultimeric channels may be responsible for the native transient outward current with slow inactivation in NG108-15 hybrid cells.

Animals↗
PubMed1992

Photochemical release of bases from nucleosides and their derivatives by water-soluble iron(III) porphyrins.

The compounds [meso-tetrakis(1-methyl-4-pyridiniumyl)porphyrinato]iron(III ) (FeIIITMPyP) and [meso-tetrakis(3,5-dichloro-1-methyl-4-pyridiniumyl)porphyrinat o]iron(III) (FeIIITCl2MPyP) photocatalysed the release of bases from nucleosides and their derivatives. The ribonucleosides, of which cytidine (C) gave the highest yield, produced much higher yields of free base than the corresponding deoxyribonucleosides. Under an argon atmosphere, virtually quantitative reduction of FeIIITMPyP into FeIITMPyP by C or 2'-deoxycytidine (dC) was observed and the reduction by C was much more effective than by dC. The increased reactivity of ribonucleosides relative to deoxyribonucleosides was ascribed to a difference in the binding properties of the porphyrin-nucleoside interactions and to base-releasing degradation of ribonucleosides from their C-2' carbon radical.

Deoxyribonucleosides↗
PubMed1992

Role of cellular superoxide dismutase against reactive oxygen metabolite-induced cell damage in cultured rat hepatocytes.

Reactive oxygen metabolites have been reported to be important in the pathogenesis of ischemia/reperfusion-induced and alcohol- and drug-induced liver injuries. We investigated the role of superoxide dismutase, cellular and extracellular, in preventing reactive oxygen metabolite-induced cytotoxicity in cultured rate hepatocytes. Cells were exposed to reactive oxygen metabolites enzymatically generated by hypoxanthine-xanthine oxidase. Cytotoxicity was quantified by measuring 51Cr release from prelabeled cells and lactate dehydrogenase release. Reactive oxygen metabolites caused dose-dependent cytotoxicity. Good correlation was found between the values for 51Cr and lactate dehydrogenase release. Reactive oxygen metabolite-induced cell damage was reduced by catalase but not by superoxide dismutase. Cellular superoxide dismutase and catalase activities were not increased after incubation with exogenous superoxide dismutase and catalase for up to 5 hr. Pretreatment with diethyldithiocarbamate inhibited cellular superoxide dismutase activity without inhibiting other antioxidants such as catalase, glutathione, glutathione reductase and glutathione peroxidase and sensitized cells to reactive oxygen metabolite-induced cytotoxicity. We conclude that hydrogen peroxide is an important mediator in hypoxanthine-xanthine oxidase-induced cell damage and that superoxide dismutase plays a critical role in cellular antioxidant defenses against hypoxanthine-xanthine oxidase-induced cytotoxicity in cultured rat hepatocytes in vitro.

Analysis of Variance↗
PubMed1992

Effects of transforming growth factor-beta 1 against the inhibitory action of interferon on DNA synthesis and viral replication in hepatitis B virus DNA-transfected cell.

Studies were undertaken to examine the effects of recombinant human transforming growth factor beta 1 (TGF-beta 1) on DNA synthesis and antiviral actions of interferons (IFNs) in HepG2 cell, a hepatoma cell line, transfected with hepatitis B virus (HBV) DNA. The inhibitory effects of IFN-alpha and -gamma on DNA synthesis of HepG2 cells were enhanced in a dose-dependent manner by a simultaneous addition of TGF-beta. The degree of suppression by the reagents was greater in HBV-nontransfected cells than in transfected cells. Inhibition of DNA synthesis was not due to direct cytotoxic effects of the additives, since the viability of HepG2 cells was comparable in the control and treated cultures as determined by trypan blue exclusion. Treatment of HBV DNA-transfected HepG2 cells with IFNs resulted in decrease in production of HB surface and e antigens, and in the level of HBV DNA, but TGF-beta reversed the IFN-induced antiviral state in HBV DNA-transfected HepG2 cells. TGF-beta had no direct effect on HBV replication. These results indicate that rTGF-beta 1 exerts a differential effect against the inhibitory actions of IFN on DNA synthesis and viral replication in HepG2 cells.

DNA, Viral↗
PubMed1992

Terminal deletion of the short arm of chromosome 3.

A boy with growth and mental retardation, flat occiput, high and broad forehead, blepharoptosis, narrow palpebral fissures, low set, malformed ears, short neck, anal atresia, deep sacral dimple is reported. High-resolution banding analysis showed terminal deletion of the short arm of chromosome 3 (46,XY,del(3)(p25.3)). Deletions of the short arm of chromosome 3 are relatively rare. The clinical features of the patient are compared with those of 19 previously reported cases.

Abnormalities, Multiple↗
PubMed1992

A 1H-15N NMR study of human c-Ha-ras protein: biosynthetic incorporation of 15N-labeled amino acids.

A 1H-15N NMR study was performed on the GDP-bound form of a truncated human c-Ha-ras oncogene product (171 amino acid residues). Resonance cross peaks of the backbone amide 1H-15N nuclei of a uniformly 15N-labeled protein were observed with heteronuclear single-quantum coherence spectroscopy (HSQC). In order to resolve overlapping cross peaks, selective 15N-labeling of one or two types of amino acid residues (Ala, Arg, Asx, Glx, Gly, His, Ile, Leu, Lys, Met, Phe, Ser, Thr, Tyr and/or Val) was carried out using appropriate E. coli mutant strains. By this procedure, all the backbone 1H-15N cross peaks were classified into amino acid types.

Amino Acids↗
PubMed1992

Development of hepatocellular carcinoma associated with increases in DNA synthesis in the surrounding cirrhosis.

The relationship between DNA synthesis activity in hepatocytes from cirrhotic tissue and development of hepatocellular carcinoma was studied in 33 posthepatitic patients with Child's grade A cirrhosis. DNA synthesis activity was measured by a bromodeoxyuridine (a thymidine analogue) labeling index, using the bromodeoxyuridine-antibromodeoxyuridine in vitro method, and the patients were followed up prospectively with frequent liver ultrasonography for 2 years. During the 2-year follow-up, 11 of the 33 cirrhotic patients developed hepatocellular carcinoma; they included 8 of the 15 patients (53%) in the high labeling index (greater than 1.5%) group compared with only 3 of the 18 patients (17%) in the low labeling index (less than 1.5) group (P less than 0.05). Five of the latter 18 subsequently had increased synthesis activity. Of these 20 patients who showed high synthesis activities either initially or subsequently, 10 (50%) developed hepatocellular carcinoma, in contrast to 1 of 13 (8%) with persistently low activities (P less than 0.05). Thus, hepatocellular carcinoma seems to develop or may become detectable when DNA synthesis in the background cirrhosis is increasing or remains high.

Adult↗
PubMed1992

Mapping of the antigenic determinants recognized by monoclonal antibodies against the M2 protein of rabies virus.

Twenty-one hybridomas producing monoclonal antibodies (moAbs) against the M2 protein of the Nishigahara (RECH) strain of rabies virus were prepared using the SDS-polyacrylamide gel-purified M2 protein as the immunogen. All moAbs reacted with the protein after Western blotting of rabies virus. By combinations of competitive binding assays, examination of the reactivity of moAbs to the cells infected with parent RCEH and two other strains, CVS and HEP-Flury, and immunoprecipitation with in vitro translation products derived from full-length and truncated cDNAs of the M2 gene, these moAbs could be classified into seven epitope groups. Of these, 20 moAbs belonging to six epitope groups were suggested to recognize an antigenic determinant in the amino-terminal region, from the 1st to the 72nd amino acid of the protein (8 moAbs from two groups directed to amino acids 1 to 72; 2 moAbs from a group directed to amino acids 9 to 72; 5 moAbs from a group directed to amino acids 17-72; 5 moAbs from two groups directed to amino acids 32 to 72). The antigenic determinant recognized by the remaining 1 moAb was shown to be located in the amino acid region from 50 to 171. These moAbs should be useful for further studies on the biological functions of the M2 protein of rabies virus.

Antibodies, Monoclonal↗
PubMed1992

Genetic drift of hepatitis C virus during an 8.2-year infection in a chimpanzee: variability and stability.

Extensive variability in genomic sequence, especially at "hypervariable regions" within the NS1/E2 region of the long open reading frame, has been reported for RNA cloned from hepatitis C virus (HCV)-infected humans and chimpanzees. However, genetic changes of HCV occurring during the course of chronic infections in humans and animals have been evaluated only for partial sequences of the HCV genome. We compared two full-length cDNA sequences of HCV obtained from a chimpanzee that was experimentally infected with the HC-J4 strain of HCV: one during the early acute phase and another during a chronic phase 8.2 years afterward. Both isolates had 9412 nucleotides plus the 3' poly(U) tail with varying length organized as follows: 5'UTR (1-341); C (342-914); E (915-1490); NS1/E2 (1491-2528); NS2 (2529-3359); NS3 (3360-5186); NS4 (5187-6380); NS5 (6381-9371); and 3'UTR (9372-9412). We found that 111 (1.18%) of the 9412 nucleotides differed between the two isolates and estimated the mutation rate as approximately 1.44 x 10(-3) base substitutions per site per year. Changes in amino acid coding were associated with 42 mutations, 8 of which were clustered at 5' end of NS1/E2 coding region, so-called "HVR-1." We analyzed the HVR-1 and HVR-2 sequences during the course of infection and found that homologous populations were present at the beginning of infection, and sequence heterogeneity within the region had developed 3.5 years later. Two regions of the HCV genome were characterized by a high degree of conservation of nucleotide sequence: 5'UTR and the 3' half of the NS4 region. The possible secondary structure of the 5'UTR suggests a region for internal ribosomal entry. The 3' half of the NS4 region may also have some specific function which depends upon a strict conservation of nucleotide sequence.

Amino Acid Sequence↗
PubMed1992

Cell growth on immobilized cell-growth factor. II. Adhesion and growth of fibroblast cells on poly(methyl methacrylate) membrane immobilized with proteins of various kinds.

The surface of poly(methyl methacrylate) membrane was partially hydrolysed and the carboxyl groups produced were coupled with various protein molecules with water-soluble carbodiimide. The immobilized proteins were a cell-growth factor insulin, cell adhesion factors fibrinogen and fibronectin, and serum proteins albumin and gamma-globulin. The insulin-immobilized poly(methyl methacrylate) membrane strongly accelerated the growth and slightly accelerated the adhesion of fibroblast cells. The immobilized fibronectin and fibrinogen enhanced the cell adhesion, and the former also accelerated the cell growth. The immobilized albumin and gamma-globulin influenced the adhesion and growth of cells very little. It was found that various proteins specifically influence the adhesion and growth of cells in an immobilized state.

Animals↗
PubMed1992

Synthesis and non-thrombogenicity of heparinoid polyurethaneureas.

Unsaturated polyurethaneureas were synthesized from 4,4'-diphenylmethane diisocyanate, 1,2-diaminopropane and polybutadiene containing hydroxyl groups at both ends of a chain. The polyurethaneureas were cast as a film and subsequently treated with N-chlorosulphonyl isocyanate to produce sulphamate and carboxylate groups on the film surface. The level of in vitro non-thrombogenicity increased with increasing degree of modification. The high blood compatibility is attributed to the low level of platelet stimulation and to heparinoid activity. It was observed that platelet stimulation depends on the surface structure of the original polyurethaneura, and that the heparinoid activity is related with the presence of sulphamate and carboxylate groups.

Animals↗
PubMed1992

Acute cytogenetic effect of benzene on rat bone marrow cells in vivo and the effect of inducers or inhibitors of drug-metabolizing enzymes.

Acute cytogenetic effects of benzene in LE rat bone marrow cells in vivo were studied. Chromosome aberrations (CA) induced by benzene consisted mainly of gaps and breaks. Cells with exchanges were rarely observed. The incidence of benzene-induced CA was at its maximum level 12 h after the p.o. or i.p. administration of benzene, dependent on the dose of benzene administered, and higher in male rats than in female rats. However, the sex difference was not observed in the repeated inhalation experiment. Chromosome damage was higher with the p.o. than the i.p. administration. LE rats were more sensitive than Wistar and SD rats to the clastogenic action of benzene. Phenobarbital and Sudan III are well known as inducers of drug-metabolizing enzymes. The peak percentage of benzene-induced CA in the rats pretreated with phenobarbital was observed 6 h after the benzene injection, and it occurred at a higher level than in the rats given only benzene. On the other hand, Sudan III pretreatment suppressed benzene-induced CA at all periods after the benzene injection. SKF-525A (a cytochrome P-450 inhibitor) and cyclohexene oxide (an epoxide hydrase inhibitor) pretreatment also suppressed benzene-induced CA.

Animals↗