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Biomedical subjects

M Oishi

Publications and source records attributed to M Oishi.

At least 73 records · Page 4Linked to original sources
PubMed1998

Localization and characterization of curved DNA in the human erythropoietin receptor gene by experimental and theoretical approaches.

We report here the locations of curved DNA in the human erythropoietin receptor gene. A total of 13 DNA bend sites were mapped by circular permutation assays, appearing at an average interval of 651.2+/-214.6 (S.D.) in the 8-kb region. The bend centers in these 13 bend sites were confirmed by oligonucleotide-based assays where most of these centers had bend angles higher than that shown by (AAACCGGGCC) x (A)20 and lower than that shown by (AAACCGGGCC)2 x (A)10. DNA curvature mapping by TRIF software, which is based on the distribution of dinucleotides, primarily AA and TT, provided a highly accurate prediction for the locations of the bend sites. They showed approximately 20 degrees to 40 degrees of bend angles demonstrated by the oligonucleotide assays and by computer analysis.

DNA↗
PubMed1998

Direct probing: covalent attachment of probe DNA to double-stranded target DNA.

We report a novel procedure, which can be applied to probing of specific DNA, for covalently attaching probe DNA to complementary sequences in double-stranded target DNA. Employing hairpin-like oligonucleotide probes in combination with successive use of recA protein and DNA ligase, probes can be attached directly to target DNA molecules without dissociation of the DNA. The hairpin-like structure of the probes was designed so that the terminus of the probe oligonucleotide can be brought into close stereochemical proximity to the terminus of the complementary strand of target DNA for ligation. Because of the elimination of the DNA dissociation and subsequent hybridization (and washing) steps in the currently employed method, the probing process has become greatly simplified and more efficient and may lead to development of fully automated probing systems.

Animals↗
PubMed1998

Direct cloning by covalent attachment of probe DNA to target DNA.

A novel cloning procedure which makes use of covalent attachment of probe DNA to specific target DNA is reported. We show that specific gene fragments found in complex genomes such as the human genome can be cloned directly from a pool of genomic DNA with very high efficiency. This direct cloning method totally eliminates certain steps in current cloning procedures such as construction of DNA libraries and colony (plaque) hybridization. The resulting process has made cloning methods simpler and more time efficient, while achieving high cloning efficiency due to the stable nature of the probe-target DNA complex through covalent bonding. Most importantly, since clones are directly obtained from a pool of genomic DNA, the isolated clones are considered to be faithful copies of the original genes. This has apparently solved the problem of isolating clones with misincorporated bases or chimeric DNA, both of which are often encountered in cloning processes using PCR or other methods involving in vitro DNA synthesis.

Animals↗
PubMed1998

Assay of nicotinamide deamidase activity using high-performance liquid chromatography.

A rapid, simple and reproducible method has been developed for the determination of nicotinamide deamidase activity using high-performance liquid chromatography (HPLC). Nicotinic acid (NA) liberated from nicotinamide (NAA) after a 15-min enzyme reaction was determined directly by HPLC without further separation steps. Both NA, the product, and NAA, the substrate were separated by reversed-phase ion-pair isocratic chromatography and detected at 261 nm. The present method could be applied to the measurement of deamidase activity in crude cell extracts prepared from several bacterial strains. The Michaelis constant of nicotinamide deamidase in Enterobacter agglomerans was 36 microM for NAA. This method is useful for the measurement of nicotinamide deamidase from various sources.

Bacteria↗
PubMed1998

Central motor conduction time and regional cerebral blood flow in patients with leuko-araiosis.

Central motor conduction time (CMCT) and regional cerebral blood flow were investigated in 21 patients with leuko-araiosis. The severity of dementia was examined using mini-mental state examination. The head magnetic stimulation was performed using an SMN-1100 magnetic stimulator and a round coil with a diameter of 17 cm. The regional cerebral blood flow was measured using the stable xenon computed tomography method. The CMCT was significantly longer in the patients with dementia than in the patients without dementia. The blood flows in the parietal cortex, frontal white matter and thalamus were significantly lower in the patients with dementia than in the patients without dementia. There were significant negative correlations between the CMCT and the blood flows in the frontal cortex, temporal cortex, frontal white matter and thalamus. The significant negative correlations suggest that the prolongation of CMCT in patients with leuko-araiosis is related to the decrease in regional cerebral blood flows.

Aged↗
PubMed1998

Genomic structure of MUNC18-1 protein, which is involved in docking and fusion of synaptic vesicles in brain.

MUNC18-1 (n-Sec1) is a brain-specific protein and is known to play a role in neurotransmitter release by mediating docking and fusion of synaptic vesicles to presynaptic membranes. The protein is also implicated in the cellular excretion process of hormones and other biological substances in other mammalian tissues and yeasts. We have studied the structure of mouse munc18-1 gene by sequencing the genomic munc18-1 gene and its 5'-flanking region. munc18-1 gene comprises 19 exons whose size ranges from 50 base pairs (2nd exon) to 1676 base pairs (19th exon) with a total gene size of approximately 56 kilobases. In the 5'-flanking region, there are several transcription factor binding sites such as for HSF2, Lyf-1, and Sp1 but no TATA or CAAT sequences. munc18-1 gene was mapped on mouse chromosome 2 between two anchor markers D2Mit152 and D2Mit242. Transfection experiments employing these and upstream sequences suggest the presence of a sequence(s) that negatively regulates the expression of munc18-1 gene.

Animals↗
PubMed1998

Conservation and continuity of periodic bent DNA in genomic rearrangements between the c-myc and immunoglobulin heavy chain mu loci.

Periodic bent DNA was mapped in the human c- myc and immunoglobulin heavy chain mu (Ig mu) loci. A total of 12 DNA bend sites in the c- myc gene and 11 sites in the Ig mu locus were aligned at average intervals of 694.2 +/- 281.4 and 654.5 +/- 222.7 bp respectively. Although some of the bend sites retained the distance of 700 bp, their periodicity was disturbed at several locations, including the exons of the c- myc gene and the enhancer element present in the Ig mu locus. Analysis of rearrangements that resulted in tumorigenesis of lymphocytes showed that the continuity of DNA bend sites was conserved in three lymphoma cell lines, Manca, BL22 and Ramos, suggesting that the genomic rearrangements gain stability by retaining their periodicity. This adds further evidence that the periodic bent DNA plays a crucial role in genomic structure.

Base Sequence↗
PubMed1998

A whole-genome analysis of allelic changes in renal cell carcinoma by in-gel competitive reassociation.

We applied a differential cloning procedure, the in-gel competitive reassociation (IGCR) method, to clone altered genomic sites from the whole genomes of renal cell carcinoma cells. After four rounds of IGCR, we obtained from two patients libraries enriched 1000- and 2500-fold for differential DNA fragments specific to allelic changes in renal cell carcinoma. In these libraries, we found differential fragments of single-copy sequences as well as repetitive sequences. The fragments exhibited allelic loss, restriction-fragment-length polymorphism, size changes, and changes in the copy number, and common allelic losses were also detected in the cancer tissues from several renal cell carcinoma patients. Some of the clones showed changes in the repeat length of microsatellites. One third (seven of 22) of the clones exhibiting these changes were mapped to chromosomes 8 or 9. Decreases in the copy numbers of mitochondrial DNA and satellite I were observed in 13 of 17 and seven of 16 renal cell carcinoma patients, respectively. This suggests that the IGCR method can be used to clone DNA fragments with various structural changes from the whole genomes of cancer tissues.

Alleles↗
PubMed1998

Kupffer cell activation in the survival discrepancy between liver grafts from enterally and parenterally fed donors.

This study was designed to investigate the effects of differences in the route of nutritional support of the donor on cold ischemia/reperfusion injury. Participation of Kupffer cells in these effects, based on the analysis of hepatic energy metabolism in early phases of reperfusion was also investigated. Orthotopic liver transplantation was performed between Large-White pigs weighing 20-30 kg after a 4-h cold preservation of the graft in Euro-Collins solution at 4 degrees C. One group was fed orally with a standard laboratory diet (FED group, n = 5), a second group was fasted and given 20% glucose intravenously (12 kJ/kg per day) (PEF group, n = 5), and a third group was fed orally with a standard laboratory diet and given GdCl3 (10 mg/kg) intravenously 24 h before operation (FEDGD group, n = 5). These treatments were given for 7 days prior to harvesting. The survival time was significantly longer in the PEF (34.8 +/- 5.5 days) and FEDGD (28.0 +/- 11.9 days) groups than in the FED (9.8 +/- 2.0 days) group (P < 0.05). The serum hyaluronic acid elimination rate determined from 1 to 2 h after reperfusion was significantly lower in the FED group than in the other two groups (P < 0.001). The glycogen content of the livers 1 h after reperfusion in all three groups had been consumed rapidly, but the ATP content of the livers was significantly reduced in the FED group alone (P < 0.01). Hepatic FFA clearance (CFFA) was moderately increased in all three groups in the early phase after reperfusion, but it was higher in the FED group than in the other two groups, with significant differences 1 and 2 h after reperfusion (P < 0.05). In conclusion, parenteral nutrition of the donors reduced cold ischemia/reperfusion injury which is related to Kupffer cell activation and, thus, was better than enteral nutrition for donor management.

Adenosine Triphosphate↗
PubMed1998

Regional cerebral blood flow and cerebrospinal fluid glutamate in leukoaraiosis.

Cerebral blood flow and cerebrospinal fluid amino acids were investigated in patients with leukoaraiosis on magnetic resonance imaging. Ten patients with leukoaraiosis and without significant cerebral infarction and ten age-matched controls without abnormality on magnetic resonance imaging were studied. The regional cerebral blood flow was measured using the stable xenon computed tomography method. The blood flow was significantly lower in the leukoaraiosis area in the leukoaraiosis group than in the same area in the control group. The cerebrospinal fluid glutamate concentration was significantly higher in the leukoaraiosis group than in the control group. There was a significant negative correlation between the blood flow in the leukoaraiosis area and the cerebrospinal fluid glutamate concentration. The high concentration of cerebrospinal fluid glutamate in patients with leukoaraiosis is considered to be related to ischaemia.

Aged↗