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Biomedical subjects

M Iizuka

Publications and source records attributed to M Iizuka.

At least 109 records · Page 6Linked to original sources
PubMed1995

Synthesis of novel oligosaccharides from leucrose by an alpha-glucosidase.

An alpha-glucosidase was purified in an electrophoretically pure state from an extract of koji culture of Aspergillus sp. KT-11. This enzyme was found to have a transferring activity when the reaction was done in a high concentration of leucrose at pH 4.5. Two kinds of transfer products, fractions I and II, were obtained from leucrose by the enzyme and they were identified as [(alpha-D-glucopyranosyl-(1-->6)-alpha-D-glucopyranosyl-(1-->6)-alpha-D- glucopyranosyl-(1-->5)-D-fructopyranose] and [alpha-D-glucopyranosyl-(1-->6)-alpha-D-glucopyranosyl-(1-->5)-D- fructopyranose], respectively. These are considered to be novel oligosaccharides.

Aspergillus↗
PubMed1995

Further studies of HLA-DR antigens on colonic epithelium in ulcerative colitis.

The aim of this study was to determine whether HLA-DR antigens are expressed on colonic epithelium in macroscopically involved areas in all cases of ulcerative colitis and whether the expression precedes inflammation (colitis). Thirty-four cases of active ulcerative colitis were studied including two cases in which island-like lesions were observed proximally apart from the main lesion, and three cases in which distal colitis became entire colitis in 8 months or less. Detection of HLA-DR antigens on colonic epithelium was performed with the immunoperoxidase method using anti-HLA-DR monoclonal antibodies. HLA-DR antigens were expressed on colonic epithelium in macroscopically involved areas in all 34 cases. In the macroscopically normal areas, the antigens were modestly expressed in six of 16 specimens (cases) in the presence of microscopic inflammation. The antigens were expressed on colonic epithelium in island-like lesions, but not in the intervening mucosa between the proximal island-like lesions and the distal main lesion. HLA-DR antigens were not expressed on colonic epithelium in the proximal non-inflamed mucosa where colitis later developed. These results lead to the conclusion that HLA-DR antigen expression does not precede, but is associated with the inflammation.

Adolescent↗
PubMed1995

Functional characterization and localization of a cardiac-type inwardly rectifying K+ channel.

We cloned inwardly rectifying K+ channel cDNAs from porcine, rat and human, which were structurally almost identical with recently reported CIR(cKATP-1). The expression of CIR alone was low and unstable in Xenopus oocytes. The CIR/GIRK1 co-expression showed an increased current amplitude. Both the CIR and CIR/GIRK1 currents increased by coexpressing G beta gamma. The CIR and CIR/GIRK1 currents displayed two qualitative differences. (1) The conductance of the CIR channel did not saturate, but that of the CIR/GIRK1 channel showed saturation at hyperpolarized potential. (2) The CIR current showed instantaneous activation upon hyperpolarization, whereas the CIR/GIRK1 current exhibited slow activation, which was fitted by the sum of two exponentials. The CIR/GIRK1 current was also different from the GIRK1 current. The activation of the CIR/GIRK1 current was approximately ten times faster than that of the GIRK1 current. The increase in current amplitude and the qualitative differences imply the formation of functional heteromultimer. The CIR/GIRK1 channel showed differences from the native muscarinic K+ channel in that the basal level before m2 receptor activation is significantly large, and that the activation kinetics are much faster. Using anti-CIR antiserum, the CIR was detected in myocardial cells of the atrium and the ventricular subendocardial layer, and in the cardiac ganglion.

Amino Acid Sequence↗
PubMed1994

Quantitative RT-PCR assay detecting the transcriptional induction of vascular endothelial growth factor under hypoxia.

Quantitative reverse transcription-polymerase chain reaction (RT-PCR) assay was used to examine the induction of vascular endothelial growth factor (VEGF) transcript in human osteosarcoma cells, MG-63, under hypoxic culture condition. Using this assay system, the expression of VEGF mRNA was estimated eight-fold higher when cells were cultured under hypoxic condition. Transcription level of hypoxanthine phosphoribosyl transferase (HPRT) mRNA was also examined as an internal control. HPRT mRNA level under hypoxia was reduced to one fourteenth. Secretion of VEGF into the cell culture medium was implied by its stimulating activity on the growth of mouse vascular endothelial cultured cells in vitro.

Aerobiosis↗
PubMed1994

Serotype G6 human rotavirus sharing a conserved genetic constellation with natural reassortants between members of the bovine and AU-1 genogroups.

Serotype G6 human rotavirus PA151 was examined by RNA-RNA hybridization in comparison with another G6 strain PA169 and two naturally-occurring G3 reassortants PCP5 and MZ58. PA151 possessed three gene segments that formed hybrids with AU-1 and seven gene segments that formed hybrids with bovine rotavirus NCDV. PA151 also possessed eight, 10 and 10 gene segments that formed hybrids with genomic RNAs from PA169, PCP5, and MZ58, respectively. Thus, PA151 was an intergenogroup reassortant formed in nature between members of the bovine and AU-1 genogroups and it shared a genome constellation with PA169, PCP5, and MZ58. These results suggest that naturally-occurring intergenogroup reassortants possessing such a genome constellation were perpetuated in human populations.

Animals↗
PubMed1994

Rotaviruses belonging to the AU-1 genogroup recovered from Israeli infants with diarrhea.

The genetic and antigenic diversity of group A rotaviruses recovered from Israeli infants has been expanded recently by the inclusion of three unusual human rotavirus strains. Two rotavirus strains (Ro-5829 and Ro-5960) were shown to be the first viruses outside Japan that resembled the AU-1 genogroup of feline like human rotaviruses in their overall genomic constellation and in the restriction pattern of their polymerase chain reaction amplified gene 4 following digestion with EcoRI. Another strain (Ro-5193) turned out to be an intergenogroup reassortant between viruses belonging to the AU-1 and the bovine genogroups and resembled in that respect similar viruses isolated from infants in Italy.

Diarrhea↗
PubMed1994

Expression of HLA-DR antigens on colonic epithelium around lymph follicles. An anomalous expression in Crohn's disease.

The relationship between the lymph follicle and expression of HLA-DR antigens on the colonic epithelium was investigated. Colonic specimens containing lymph follicles were examined immunohistochemically for HLA-DR expression. Thirty-six biopsy specimens (29 from macroscopically uninvolved areas and seven from aphthoid lesions) were obtained from 10 patients with Crohn's disease, and another 43 specimens were obtained from 33 patients with various intestinal diseases (non-Crohn's disease). HLA-DR antigens were expressed on the epithelium around the lymph follicle in both groups. However, the rate of expression (31/36) in Crohn's disease was significantly higher than that (5/43) in non-Crohn's diseases (P < 0.001). In addition, the extent and intensity of expression were broader and stronger in Crohn's disease than in non-Crohn's disease. This study is the first demonstration of anomalous HLA-DR expression on the epithelium around the lymph follicle in Crohn's disease.

Adult↗
PubMed1994

Molecular characterization of a human group A rotavirus isolated from an adult with severe dehydrating diarrhea and its relationship to strains concurrently circulating among children.

BACKGROUND: While group A rotavirus is widely accepted as an important etiology of acute gastroenteritis in children, this agent rarely causes severe diarrhea in adults and, thus, is not considered by physicians to be an etiological agent for such diseases. OBJECTIVES: None of the reports describing such rare cases in adults has examined the causative strains genetically in detail. STUDY DESIGN: We determined the G type, the gene 4 genotype, the electropherotype, and the genomic RNA constellation (genogroup) of a group A rotavirus strain isolated from an adult with severe diarrhea. This patient, the first documented case of rotavirus diarrhea in adult in Japan, suffered from severe dehydrating diarrhea with 'rice-water' appearance, vomiting and little abdominal pain, presenting a clinical picture typical of cholera. RESULTS: Rotavirus antigen and genomic RNA were detected in the stool but other enteric pathogens including Vibrio cholerae responsible for the disease were not isolated. Molecular characterization revealed that the patient was infected with a strain of the DS-1 genogroup with G2 and gene 4 genotype 4 which was circulating among children during the same period. CONCLUSIONS: The result that the same group A rotavirus strain was isolated from children and an adult underlines the necessity of examining rotavirus in adults with acute diarrhea.

Journal Article↗
PubMed1994

The distribution of G (VP7) and P (VP4) serotypes among human rotaviruses recovered from Japanese children with diarrhea.

Both the G (VP7) and P (VP4) serotypes of human rotaviruses collected over a 10-year period from Japanese children with diarrhea were determined by recently-developed polymerase chain reaction-based typing assays. The combination of G1 and P8 was found in 65.2% and the combination of G2 and P4 was found in 15.2%. For the rest of the specimens, only a few other combinations occurred and their relative frequencies were less than 10%. The viruses carrying P9 were always associated with G3 as is the prototype strain AU-1.

Antigens, Viral↗
PubMed1994

ADP inhibits the sliding velocity of fluorescent actin filaments on cardiac and skeletal myosins.

We studied the effect of MgADP on the mechanical interaction of actomyosin in cardiac and skeletal muscles using an in vitro motility assay. The sliding velocities of fluorescently labeled actin filaments on rat cardiac and skeletal myosins were measured at various MgATP and MgADP concentrations. The filament velocity depended on MgATP concentration according to classic Michaelis-Menten kinetics with apparent Michaelis constants (Km) of 43 and 137 mumol/L and maximum velocity of 5.6 and 8.6 microns/s for cardiac and skeletal myosins, respectively. The presence of 2 mmol/L MgADP decreased the filament velocity and shifted the substrate concentration dependence of the velocity toward higher MgATP concentrations, yielding the inhibition constants of 194 and 478 mumol/L for cardiac and skeletal myosins, respectively. The activation energies determined by the temperature dependence of the velocity were 61 and 83 kJ/mol for rat V1 and rabbit cardiac myosins, which were similar to those of the dissociation rate constant of actomyosin-ADP complex reported in a solution study. The inhibition of the velocity by MgADP can be explained by the crossbridge scheme in which MgADP competes with MgATP for the substrate site on myosin molecules. In cardiac myosin, addition of a concentration of MgADP as low as 25 mumol/L significantly inhibited the velocity in the presence of 2 mmol/L MgATP, suggesting that increased intracellular MgADP may reduce the rate of crossbridge detachment, resulting in a decreased ATP consumption and an increased economy of force production under ischemic conditions. The present results support the idea that MgADP may be a physiologically important modulator of contraction in cardiac muscle.

Actins↗
PubMed1994

Chemical structures of hetero-oligosaccharides produced by Arthrobacter sp. K-1 beta-fructofuranosidase.

The structures of hetero-oligosaccharides obtained by the action of transglycosylation of Arthrobacter sp. K-1 beta-fructofuranosidase, using sucrose as the fructosyl donor, and several mono- and di-sacchrides as the acceptors were investigated. The main transfer products to most reducing mono- and di-sacchrides were non-reducing oligosaccharides with a fructosyl residue linked to a hemiacetal hydroxyl group. In the presence of L-sorbose, the enzyme produced 2-O-beta-D-fructofuranosyl-alpha-L-sorbopyranoside as the major product. With D-galactose or L-arabinose, the enzyme produced not only non-reducing oligosaccharides, but also reducing oligosaccharides, which were identified as 3-O-beta-D-fructofuranosyl-D-galactopyranose and 4-O-beta-D-fructofuranosyl-L-arabinopyranose, respectively. When a non-reducing sugar such as methyl alpha-glucoside was used as an acceptor, the product formed had a fructosyl residue linked at the C6 hydroxyl group.

Arthrobacter↗