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Biomedical subjects

M C Yoshida

Publications and source records attributed to M C Yoshida.

At least 91 records · Page 5Linked to original sources
PubMed1990

Transcriptional down-regulation of the rearranged C-myc expression in murine cell hybrids between a plasmacytoma and a T-cell lymphoma.

Regulation of the rearranged and non-rearranged c-myc expression was studied in murine cell hybrids (SBWI and SBWII) between plasmacytoma (S194) and T-cell lymphoma (BW5147) cells. Expression of the rearranged c-myc of heterogeneous mRNA sizes (1.8 approximately 2.4 kb) was markedly down-regulated in these hybrids regardless of retention of the gene. On the other hand, expression of the non-rearranged c-myc (2.4 kb) was not significantly affected in these hybrids. Treatment of SBWI hybrid cells with cycloheximide enhanced the non-rearranged c-myc 2- to 4-fold but did not release the down-regulation of the rearranged c-myc at all, suggesting that the down-regulation of the rearranged c-myc in the hybrid cells was mainly at a transcriptional rather than a post-transcriptional level. This was supported by the results of nuclear run-on assay: the high level of run-on transcripts in S194 cells declined in SBWI hybrid cells comparable to the level in BW5147 cells. The rearranged c-myc was hemi-methylated in S194 cells and the pattern was the same in SBWI hybrid cells. Furthermore, down-regulation of the rearranged c-myc in the hybrid was also not restored by treatment with 5-azacytidine (5-AzaC), 12-O-tetradecanoylphorbol-13-acetate (TPA) or forskolin, suggesting no causative involvement of DNA methylation or protein phosphorylation in down-regulation. Higher DNase I sensitivity of the rearranged c-myc in S194 cells decreased to a similar extent to that of the non-rearranged c-myc after cell fusion with BW5147 cells. These results suggest that expression of the rearranged c-myc is down-regulated at the level of transcription in murine cell hybrids between a plasmacytoma and a T-cell lymphoma, probably by changing chromatin configuration around the gene from the open to the closed state.

Animals↗
PubMed1990

Organization of variable region segments of the human immunoglobulin heavy chain: duplication of the D5 cluster within the locus and interchromosomal translocation of variable region segments.

We have studied the organization of variable region (V) genes of the human immunoglobulin heavy chain (H) by cosmid cloning. We isolated two independent immunoglobulin D5 clusters (D5-a and D5-b) from cosmid libraries of the human genome. Restriction maps of these two regions showed that downstream 15 kb portions of the 55 kb overlap were different although upstream 40 kb portions were almost identical. Four more D segments, (DM, DXP, DA and DK) were found around the D5 segment in the conserved region of each cluster. Nucleotide sequences of the corresponding D segments from each cluster were almost identical and they encoded potentially functional D regions. Analysis using human-rodent somatic cell hybrids demonstrated that both clusters were located in the immunoglobulin heavy chain (H) locus on chromosome 14, suggesting that the D5-a and D5-b regions evolved by internal duplication within this locus. We also isolated a 60 kb DNA region carrying four VH segments, designated as VH-F region, which was located on chromosome 16. Nucleotide sequences of the four VH segments were determined. Two of them encoded potentially functional VH segments, and the other two were pseudogenes. Some more VH segments were found to be located outside chromosome 14, by Southern blot hybridization of human-rodent hybrid cell DNAs. These results provide further evidence that the human VH locus has undergone recent reorganization.

Amino Acid Sequence↗
PubMed1990

Cytochrome P-450 and chromosome damage by cyclophosphamide in LEC strain rats predisposed to hereditary hepatitis and liver cancer.

LEC strain rats predisposed to hereditary hepatitis and liver cancer were examined for hepatic drug-metabolizing ability and the inducibility of chromosome damage by cyclophosphamide (CP) in somatic cells. Whereas the hepatic cytochrome P-450 contents and the activities of cytochrome P-450-catalyzed monooxygenases were lower in females than in males of both LEC and control LEA strains, male LEC rats exhibited significantly reduced cytochrome P-450 contents and monooxygenase activities compared with male LEA rats. When exposed to CP, a promutagen/procarcinogen requiring P-450-dependent metabolic activation, the frequencies of chromosome aberrations and sister-chromatid exchanges (SCEs) in bone marrow cells tended to be lower in females than in males of each strain and lower in LEC than in LEA rats of the same sex. In particular, the CP-induced SCEs were substantially lower in LEC rats. However, no such sex and strain differences were found in the SCE frequencies in regenerating hepatocytes of partially hepatectomized rats exposed to CP.

Animals↗
PubMed1990

Superoxide dismutase activity and chromosome damage in cultured chromosome instability syndrome cells.

The basal levels of superoxide dismutase (SOD) activity and chromosome aberration (CA) and sister-chromatid exchange (SCE) frequencies were examined in cultured fibroblasts or Epstein-Barr virus (EBV)-transformed lymphoblastoid cell lines (LCLs). These cells were derived from patients with chromosome instability syndromes (CISs) including Bloom's syndrome (BS), Fanconi's anemia (FA) and ataxia telangiectasia (AT). Embryonal fibroblasts and LCLs from normal subjects served as controls. Although LCLs tended to exhibit a higher SOD level than fibroblasts due to an elevation of Cu/Zn-SOD activity, BS and FA fibroblasts with increased frequencies of CAs and/or SCEs showed abnormally elevated SOD activity due to the manifold increase of Mn-SOD levels compared with control cells. However, BS and AT LCLs with almost control levels of CA and SCE frequencies showed no, or a slightly elevated, SOD activity, suggesting a possible selection of such cells during EBV transformation. The observed parallelism between the SOD activity and the cytogenetic manifestation may imply an involvement of active oxygen species, especially superoxide radicals, in the increased chromosome damage of CIS cells.

Ataxia Telangiectasia↗
PubMed1990

Two-dimensional electrophoretic analysis of hepatitis-associated polypeptides in liver of LEC rats developing spontaneous hepatitis.

High-resolution two-dimensional polyacrylamide gel electrophoresis in combination with silver staining was used to analyze between 800 and 1000 cytosolic and particulate polypeptides from age-matched livers of normal male Long-Evans rat with Agouti coat color (LEA) and Long-Evans rat with Cinnamon-like coat color (LEC) rats with hereditary trait of hepatitis at ages long before, immediately prior to, and just after the onset of hepatitis. Although the electrophoretic patterns of polypeptide expression were very similar with respect to the overall spot patterns, a number of polypeptides which differed either qualitatively or quantitatively were noted. Two constitutively expressed cytosolic polypeptides, P29.5 (Mr 29.5 kDa/pI 6.73) and P30 (30 kDa/6.70), were not detected in livers of LEC animals at any age. In the normal LEA rats both P29.5 and P30 were detected as early as one day after birth and both were expressed at similar concentrations at all ages. In the LEC rats P30-C (30 kDa/6.68) was constitutively expressed in close proximity to the expected position of P30, and P30-C was not detected in the LEA rats. By means of non-equilibrium pH gradient electrophoresis two relatively basic polypeptides were detected in the LEC rats. P18ne was detected immediately prior to and P27ne immediately after the clinical manifestation of hepatitis. Experiments in F1 backcross ([LEA x LEC] x LEC) animals, however, failed to demonstrate any genetic link between either the expression or lack of expression of P29.5, P30, P30-C, or P18ne and hepatitis development. P27ne was detected in all backcross animals exhibiting hepatitis, but was never observed in LEC rats prior to the onset of hepatitis. Although we were unable to identify any unique loss of expression of polypeptides which are genetically linked to hepatitis susceptibility in LEC rats, specific subsets of quantitatively modulated polypeptides were detected.

Animals↗
PubMed1990

Chromosome regional mapping for the human thyroid stimulating hormone beta subunit (TSHB) gene.

The human thyroid stimulating hormone beta subunit (TSHB) gene, located on chromosome 1, was studied to determine its subregional location by in situ hybridization and Southern blot analysis of human x mouse hybrid cells. The results allowed localization of TSHB to the proximal portion of 1p22, which is in the region of localization of the linkage group including amylase (AMY), nerve growth factor beta subunit (NGFB), and NRAS, which are conserved in humans and rodents.

Blotting, Southern↗
PubMed1990

Molecular cloning and chromosomal localization of a gene coding for human cardiac myosin heavy-chain.

alpha- and beta-human cardiac myosin heavy-chain (MHC) genes, which correspond to MYH6 and MYH7, respectively, according to Human Gene Mapping nomenclature, were isolated from human genomic and cDNA clones, using two rat cardiac pCMHC26: alpha-MHC type; and pCMHC5: beta-MHC type as probes, and characterized. The alpha-MHC type cardiac genomic DNA clone and the beta-MHC type cardiac cDNA clone were used as probes in the Southern analysis of human genomic DNA from human-Chinese hamster or human-mouse somatic cell hybrids. The results showed that the human cardiac MHC gene is assigned to chromosome 14 and the human cardiac and skeletal MHC genes do not cosegregate as do the mouse cardiac and skeletal MHC genes. For further analysis, a regional mapping method was used. DNA from 4 human deletion and 3 human duplication cell line were prepared for southern blotting, hybridized with human cardiac alpha- and beta-MHC DNA probes, and the hybridization intensity relative to 46, XX or 46, XY DNA was estimated. The results showed that two human cardiac MHC genes segregated with the 14cenq13 region of the long arm of human chromosome 14. In situ hybridization of 3H-labeled human cardiac alpha-MHC probe to normal human metaphase chromosome independently confirmed this result.

Animals↗
PubMed1990

Chromosomal assignment of the gene for the ubiquinone-binding protein of human mitochondrial cytochrome bc1 complex.

The ubiquinone-binding protein (QP-C) is a nuclear-encoded subunit of the cytochrome bc1 complex in the mitochondrial respiratory chain and is thought to be involved in the electron transfer reaction coupled to energy transduction. We recently isolated a nuclear gene for human QP-C and used, in the present study, its fragment as a probe for Southern blot analysis of EcoRI-digested DNAs prepared from 14 human-mouse somatic cell hybrids. The results indicated that the human QP-C gene is located on chromosome 8.

Animals↗
PubMed1990

Clinico-pathological studies of LEC rats with hereditary hepatitis and hepatoma in the acute phase of hepatitis.

The LEC rat, which suffers from hereditary hepatitis, was examined for elucidation of its clinicopathological characteristics during development of the acute phase of hepatitis by quantitative analyses of histological observations of the liver in combination with laboratory data on various serum enzymes. The progression of acute hepatitis in the LEC rat was observed to begin insidiously early in life, i.e., a few enlarged hepatocytes and Councilman bodies appeared at around 8 weeks of age without clinical signs. Furthermore, it was revealed that the acute phase of hepatitis started with a remarkable increase of Councilman bodies, large nuclei and hepatocytes in mitosis in the liver 3 to 4 weeks before the onset of fulminant hepatitis, which is characterized by the elevation of serum enzyme activities such as GOT, GPT and gamma-GTP, and the onset of jaundice. From those observations, three stages were proposed for the progression of acute hepatitis in the LEC rat.

Acute Disease↗
PubMed1989

Human cardiac myosin heavy chain gene mapped within chromosome region 14q11.2----q13.

Our previous report demonstrated that two human cardiac alpha- and beta-myosin heavy-chains (MHCs) which correspond to MYH6 and MYH7 respectively, according to Human Gene Mapping nomenclature, were mapped to human chromosome 14 and that human cardiac and skeletal MHC genes do not cosegregate. For further analysis, the regional mapping method was used. DNA from 4 human deletion and 3 human duplication cell lines were prepared for southern blotting, hybridized with human cardiac alpha- and beta-MHC DNA probes, and the hybridization intensity relative to 46,XX or 46,XY DNA was estimated. The results showed that two human cardiac MHC genes segregated with the 14cen----q13 region of the long arm of human chromosome 14. In situ hybridization of 3H-labeled human cardiac alpha-MHC probe to normal human metaphase chromosome independently confirmed this result.

Base Sequence↗
PubMed1989

Molecular cloning and chromosomal assignment of a human perforin (PFP) gene.

Human perforin cDNA was isolated and the complete nucleotide sequence of the gene determined. The deduced amino acid sequence of human perforin showed 68.4% similarity to that of mouse perforin. RNA blot analysis of the human perforin gene revealed that the gene product is expressed preferentially in killer-type cells among cell lines tested, and in large granular lymphocytes among the peripheral blood mononuclear cells. In situ hybridization analysis with a human perforin cDNA probe revealed that the human perforin (PFP) gene is located on chromosome 17q11-21.

Base Sequence↗
PubMed1989

Chromosomal mapping of the mouse IL-4 and human IL-5 genes.

We mapped the mouse interleukin (IL)-4 gene on chromosome 11 by restriction fragment length polymorphism using recombinant inbred mouse strains. The human IL-5 gene was mapped on chromosome 5q 23.3-31.1 by in situ hybridization. Because the granulocyte macrophage colony-stimulating factor (GM-CSF) and IL-3 genes were previously mapped on mouse chromosome 11 (within a 230-kb region) and human chromosome 5, the IL-4 and IL-5 genes are likely to cluster on the same chromosomes with the GM-CSF and IL-3 genes in both species.

Animals↗
PubMed1989

Gene expression of placental glutathione S-transferase in hereditary hepatitis and spontaneous hepatocarcinogenesis of LEC strain rats.

Liver tissues of LEC rats, which develop fulminant hepatitis and hepatocellular carcinoma (hepatoma), were examined by Northern blot analysis using a cDNA probe of rat placental glutathione S-transferase (GST-P). GST-P gene expression was observed not only during hepatocarcinogenesis but also in fulminant hepatitis before development of chronic hepatitis and hepatoma in LEC rats. Cholangiofibrosis in LEC rats also showed high GST-P expression. A transplantable cell line derived from spontaneous LEC hepatoma exhibited a remarkably high expression. By contrast, very weak expression was observed in the livers of young LEC rats before development of hepatitis and control strain rats. Thus, spontaneous hepatic lesions in LEC rats may provide a new clue to elucidate the mechanism of GST-P gene expression.

Animals↗
PubMed1989

Chromosome analysis of canine transmissible sarcoma cells.

The chromosomal banding patterns of canine transmissible sarcoma (CTS) cells were analyzed and compared to those of normal canine cells with four banding techniques. In addition, N-myc and N-ras oncogenes on the chromosomes of the CTS cells were investigated by the in situ hybridization method. The modal chromosome number of the CTS cells was 58:17 metacentrics and 41 acrocentrics. Based on their G- and Q-banding patterns most of the chromosomes of the CTS cells were present in normal cells except for the second largest metacentric chromosomes. It was considered that the metacentric chromosomes of the CTS cells results from Robertsonian translocation of normal chromosomes. The long arm of the second largest metacentric element of the CTS cells was stained negatively by the Q-banding technique. The C-band was found on the long arm of the second largest metacentric element and three pairs of N-bands were recognized in the same region. It was suggested that this amplification of N-bands enhanced tumorigenic properties in the CTS. No N-myc or N-ras oncogenes were detected on chromosomes of the CTS cells by the in situ hybridization method.

Animals↗
PubMed1989

High resolution chromosome banding in the Norway rat, Rattus norvegicus.

High resolution banded chromosomes were prepared from a synchronized culture of rat fibroblasts. A maximum of 457 bands per haploid chromosome set were observed. This represents a two-fold increase when compared to the number of bands visualized in mid-metaphases using standard procedures. By reference to both G- and Q-banded karyotypes, we constructed improved idiograms of rat chromosomes at 300- and 400-band stages, respectively.

Animals↗
PubMed1989

Regional assignment of nonspecific cross-reacting antigen (NCA) of the CEA gene family to chromosome 19 at band q13.2.

Nonspecific cross-reacting antigen (NCA) is a member of the carcinoembryonic antigen (CEA) gene family. Recently, a DNA segment for part of the human NCA gene was isolated and sequenced. We mapped this gene by Southern blot analysis of hybrid cells and by in situ hybridization. The Southern blot analysis indicated that the NCA gene is on human chromosome 19 and the in situ hybridizations localized the gene to band 19q13.2.

Animals↗
PubMed1989

Regional mapping of the FOS oncogene to rat chromosome 6q21----q23.

Using a panel of rat x mouse somatic cell hybrids and in situ hybridization, we determined the chromosomal location of the rat FOS gene locus. Southern blot analysis assigned this oncogene to rat chromosome 6. In situ hybridization confirmed this finding and mapped the gene more precisely to 6q21----q2.

Animals↗