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Biomedical subjects

Y Choi

Publications and source records attributed to Y Choi.

At least 343 records · Page 19Linked to original sources
PubMed1988

Extension of the H-2 TLb molecular map. Isolation and characterization of T13, T14, and T15 from the C57BL/6 mouse.

A region of the TLb locus encompassing T11 to T13 contains retroviral sequences TLev1 and TLev2. As part of a study to determine whether the retroviral elements are involved in the expression of TL genes, the genomic organization of this region was reexamined in greater detail. A result of these investigations is the extension of the H-2 TLb molecular map. Two additional TL genes have been isolated from C57BL/6 mice, T14 and T15. The genomic organization of T9 through T15 is presented. The nucleotide sequence has been determined for exons 4, 5, and 6 of T13. As a result of a C to T conversion, a termination codon is introduced into exon 4, indicating that T13 either encodes a secreted protein or is a pseudogene. T13 was found to be more homologous to the H-2 genes outside the TL region. T14 has been physically disrupted by the integration of TLev1, and the H-2 sequences appear to have diverged greatly. The relationship of the TL regions of the b and c haplotypes has been investigated using numerous low copy probes. The genome of BALB/c (TLc) is shown to lack a counterpart of the T13-T15b region. Homologous regions exist in the two haplotypes; yet considerable polymorphism is observed. TLb mice do not express TLa on the cell surface of normal thymocytes while TLc mice do; TLa expression is activated in many TLb leukemias. The diversity seen in the T13-T15 region may provide insights into the phenotypic expression or regulatory mechanisms of TL expression in these two haplotypes.

Animals↗
PubMed1988

A renal biopsy study of hepatitis B virus-associated nephropathy in Korea.

The pathogenic role of the hepatitis B virus (HBV) infection for glomerulonephritis (GN) is not clear. The frequency of HBsAg has been studied in sera of 732 consecutive patients who have glomerular diseases by using radioimmunoassay. The frequency of HBs antigenemia was 11.9%, which was not different from that in the general population of South Korea. Of the 87 HBsAg seropositive patients with GN, 29 cases with membranoproliferative GN (MPGN) and eighteen with membranous nephropathy (MN) were diagnosed as having HBV-associated nephropathy. Eighty-seven and one-half percent of the adults with MPGN and 80% of the children with MN were HBsAg carries. The morphologic findings and laboratory data in cases with HBV-associated MPGN and MN did not differ significantly from those observed in patients with MPGN and MN without circulating HBsAg. Yet mesangial deposits were more frequently noted in patients with HBV-associated MN when compared to others with idiopathic MN. Glomerular deposits of HBsAg were not detected using indirect immunofluorescence technique. Even though HBsAg was not demonstrable within the glomeruli, HBV infection seems to play an important role in the pathogenesis of MPGN in Korean adults and MN in children.

Adolescent↗
PubMed1988

Regulation of H-2 class I gene expression in virally transformed and infected cells.

Early studies of the resistance and susceptibility of mouse strains to radiation-induced leukemia virus have demonstrated the important role of altered histocompatibility (H-2) antigen expression in the effectiveness of the immune response of the host to virus-infected and transformed cells. Changes in H-2 gene expression have now been correlated with disease resistance in a variety of viral systems. The experiments discussed indicate that viruses may directly or indirectly affect H-2 antigen expression at various levels of gene expression. These investigations generate a framework for approaching a molecular understanding of viral-induced changes in H-2 gene expression.

Animals↗
PubMed1987

Childhood renal diseases in Korea. A clinicopathological study of 657 cases.

Between June 1975 and March 1987, 662 renal biopsies were performed in 657 children at Seoul National University Children's Hospital. Nephrotic syndrome was the most indication for renal biopsy and accounted for 62% of all cases. Of these, 57% showed minimal change lesions and 21% showed focal segmental glomerular sclerosis. Nephropathy, associated with Australia-antigen-positive hepatitis, was the most prominent cause of secondary nephrotic syndrome, and of these patients membranous nephropathy was found in 86%. Diffuse proliferative glomerulonephritis was found in 60% of patients with acute nephritic syndrome. Fifty-eight percent of children with haematuria were found to have either IgA nephropathy or Henoch-Schönlein nephritis. Fifteen children with acute renal failure were biopsied, 2 of whom had haemorrhagic fever.

Child↗
PubMed1987

Epidural butorphanol or morphine for the relief of post-cesarean section pain: ventilatory responses to carbon dioxide.

To determine the safety, efficacy, and the ventilatory responses to carbon dioxide (CO2) of epidurally administered butorphanol or morphine, 122 healthy women who underwent cesarean section with epidural anesthesia were studied. Patients were randomly assigned to receive one of four epidural regimens for the relief of postoperative pain: 5 mg morphine (n = 32), 4 mg butorphanol (n = 30), 2 mg butorphanol (n = 29), or 1 mg butorphanol (n = 31). Epidural morphine provided satisfactory analgesia with slow onset and long duration of approximately 21 hr. When butorphanol was administered, analgesia of rapid onset was seen with increasing duration and effectiveness observed with increasing dose; approximately 8 hr when using 4 mg. Sixty-two percent of the patients who received morphine had pruritus. Somnolence was the main side effect encountered in patients who received epidural butorphanol. The ventilatory response to CO2 was depressed after morphine and after 2 and 4 mg butorphanol, but the duration of depression was more prolonged after morphine. It is concluded that epidural butorphanol is effective in providing pain relief after cesarean section with minor side effects. However, patients must be observed closely because of possible respiratory depression.

Butorphanol↗
PubMed1985

Quantitative analysis of collagen, protein and DNA in fixed, paraffin-embedded and sectioned tissue.

Modifications and adaptations of chemical techniques have been used to quantitate hydroxyproline (collagen), total protein and DNA in fixed, paraffin-embedded and sectioned tissue. The assays are rapid and sensitive to between 0.1 and 1.0 micrograms of each of the three components. Values for the ratio of collagen to total protein or collagen per DNA obtained from sectioned material are the same as values derived from fresh or fixed starting material. Depending on the tissue and the sample size, as little as three to five 5 micron thick sections can be analysed for these three components. The ratios of collagen per total protein or collagen per DNA are given for several murine tissues. The assay of these components in tissue sections will allow a more precise correlation between histological appearance and the quantitative biochemical changes that may accompany many pathological disorders. The techniques are particularly useful in retrospective studies where the experimental material may be en bloc.

Animals↗
PubMed1984

Association of simian virus 40 T antigen with the nuclear matrix of infected and transformed monkey cells.

The subnuclear distribution of simian virus 40 large T antigen within nuclei of transformed Cos and C6 monkey cells was examined. Cos cells express wild-type T antigen but lack viral sequences required for DNA replication, whereas C6 cells contain a functional viral origin but express a replication-defective mutant T antigen which is unable to bind specifically to viral DNA. Discrete subpopulations of T antigen were isolated from the soluble nucleoplasm, chromatin, and nuclear matrix of both cell lines. Although only a small quantity (2 to 12%) of the total nuclear T antigen from Cos cells was associated with the nuclear matrix, a high proportion (25 to 50%) of C6 T antigen was bound to this structure. Results obtained from lytically infected monkey cells showed that early in infection, before viral replication was initiated, a higher proportion (22%) of T antigen was found associated with the nuclear matrix compared with amounts found associated with this structure later in infection (5 to 8%). These results suggest that an increased association of T antigen with this structure is not correlated with viral replication. T antigen isolated from the C6 nuclear matrix was more highly phosphorylated than was soluble C6 T antigen and was capable of binding to the host p53 protein. C6 DNA contains three mutations: two corresponding to N-terminal changes at amino acid positions 30 and 51 and a third located internally at amino acid position 153. By analysis of the subnuclear distribution of T antigen from rat cells transformed by C6 submutant T antigens, it was determined that one or both of the mutations at the NH2 terminus are responsible for the increased quantity of C6 T antigen associated with the nuclear matrix. These results suggest that neither a functional viral DNA replication origin nor the origin binding property of T antigen is required for association of this protein with the nuclear matrix.

Animals↗