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Biomedical subjects

G Kawaguchi

Publications and source records attributed to G Kawaguchi.

10 recordsLinked to original sources
PubMed1995

[A case report of Cabrol procedure with zero-porosity graft in a patient of annulo-aortic ectasia with severe aortic regurgitation].

A 63-year-old man was admitted to the hospital for the treatment of annulo-aortic ectasia with severe aortic regurgitation. The aortogram revealed dilatation of the aortic root and severe aortic regurgitation. LVEDVI was 207 ml/m2 but the patient was asymptomatic. Aortic root reconstruction was performed with Cabrol procedure using zero-porosity graft. There was no evidence of bleeding due to this graft and the percent dilatation of this graft was 33%. This zero-porosity graft of knitted Dacron coated with gelatin seems to offer some advantages to the operation. The patient is in stable health today, but perioperative occurrence of VPCs may have owed to diminished LV function caused by severe aortic regurgitation.

Aorta, Thoracic↗
PubMed1994

Effect of single amino acid substitution at residue 167 of HLA-B51 on binding of antibodies and recognition of T cells.

We recently showed that a single amino acid substitution of tryptophane into glycine at residue 167 facing the "A pocket" forms a novel HLA-B51 subtype, B*5103, which is serologically discriminated as HLA-BTA. CDC assay of human alloantisera specific for the HLA-B5 CREG against B*5103- or B*5101-transfected human B-cell line, Hmy2C1R (C1R), supported the belief that human alloantisera can discriminate B*5103 from B*5101 Ag. Moreover, we found that 4D12 anti-B5, B35 CREG mAb cannot bind to B*5103 Ag on C1R cells or L cells although it binds to B*5101 Ag on both cells. These results indicate that alloantibodies can detect a single amino acid substitution at residue 167. Furthermore, it was suggested that 4D12 mAb recognizes the structure formed by the HLA-peptide complex since this mAb did not bind to empty HLA-B5, B35 CREG Ag on RMA-S transfectants. Six of eight anti-HLA-B*5101 CTL clones are not able to kill C1R cells expressing B*5103, indicating that conformational change of the A pocket by substitution at residue 167 has a crucial influence on recognition of alloreactive T cells. Therefore, discrimination of B*5103 from B*5101 would seem to be important in bone marrow transplantation.

Amino Acid Sequence↗
PubMed1994

The role of the conserved residue in pocket A and the polymorphic residue in pocket E of HLA-B*3501 in presentation of human minor histocompatibility peptides to T cells.

We investigated T cell recognition for human minor histocompatibility (hmH) peptides using HLA-B*3501 restricted, hmH specific cytotoxic T lymphocytes (CTL) clones. These CTL clones killed C1R cells expressing HLA-B*3501 but not C1R cells expressing chimeric antigens between HLA-B*3501 and HLA-B*5101. They also failed to kill C1R cells expressing HLA-B*3501 mutants at residue 152 (B*3501-V152E) or at residue 171 (B*3501-Y171H). The CTL clone failed to kill C1R cells expressing these mutant molecules loaded with the hmH peptides isolated from C1R-B*3501 cells although it killed a self-B cell line expressing HLA-B3501 loaded with the specific hmH peptides. The CTL clone also failed to kill T2 cells expressing the mutant molecules loaded with the specific peptides whereas it killed T2 cells expressing HLA-B*3501 loaded with the specific peptide. On the other hand, naturally occurring specific hmH peptides were isolated from purified B*3501-V152E and B*3501-Y171H molecules, indicating that both HLA-B*3501-V152E and HLA-B*3501-Y171H molecules can bind the hmH peptides. These findings indicate that both the conserved residue 171 in pocket A and the polymorphic residue 152 in pocket E are critical in recognition of the T cells but not binding of the hmH peptides. Furthermore, these results provide the possibility that the TCR recognizes a conformational structure of hmH peptides bound to HLA-B*3501 molecules.

Antigen Presentation↗
PubMed1994

Hepatitis B virus carrier with low titer of antibody to hepatitis B core antigen.

Of 798 hepatitis B virus (HBV) carriers, 22 had low titers (lower than 80% inhibition in 200- or 400-fold diluted serum) of antibody to hepatitis B core antigen (anti-HBc). Among these 22 patients, there were 12 (1.50%) with viremia who were positive for hepatitis B e antigen and had a high titer of HBV-associated DNA polymerase activity. Among these 12 patients, four showed no significant change in the anti-HBc titer, while four others showed significant increases in the anti-HBc titer during the follow-up periods. The former all remained asymptomatic carriers (ASCs), while the latter all developed chronic hepatitis (CH). The liver histology of four patients (ASC: 2, CH: 2) showed mild inflammation, and the localization of hepatitis B core antigen (HBcAg) in the liver specimens showed a nuclear pattern in the two ASCs, but a nuclear plus cytoplasmic pattern in the two CH cases. In HBV carriers, the increase in anti-HBc titer seems to be closely correlated to the change in HBcAg localization from the nucleus to the cytoplasm in the liver. Therefore, rising titers of anti-HBc were assumed to be associated with increased expression of HBcAg on the hepatocyte, and hence increased immune-mediated hepatic damage and the onset of hepatitis in ASC with low titer of anti-HBc.

Adolescent↗
PubMed1993

Structural analysis of HLA-B40 epitopes.

Two genes encoding HLA-B60 or HLA-B61 were cloned from Japanese and the exons of their genes were sequenced. One silent mutation was observed at the exon 1 between HLA-B60 (B*40012) and B*40011. Seven nucleotide substitutions were seen at the exon 3 between HLA-B61 (B*4006) and B*4002. Three substitutions at codon 95, CTC in B*4002 to TGG in B*4006, changed Leu in B*4002 to Trp in B*4006, while two substitutions at codon 97, AGC in B*4002 and ACG in B*4006, changed Ser in B*4002 to Thr in B*4006. Since B*4002 shares the epitope of alloantibodies specific for HLA-B61, two HLA-B61 subtypes are discriminated by two amino acid substitutions at residues 95 and 97. B*40012 and B*4006 differ by four amino acid substitutions on the beta sheet and five amino acid substitutions on the alpha 2 helix. Since the residues at the beta sheet seem hardly to affect the binding of alloantibody, it is suspected that the residues on the alpha 2 helix provide epitopes for alloantibodies that discriminate allospecificity between HLA-B60 and HLA-B61.

Amino Acid Sequence↗
PubMed1992

Two subtypes of HLA-B51 differing by substitution at position 171 of the alpha 2 helix.

Newly defined antigens of the B5, B35 cross-reacting group have been found in Japanese and North American Indians. Nucleotide sequencing of the alleles encoding the Japanese B5.35 antigen and the variant B5 antigen from the Piman Indians show them to be identical. This new allele, B*5102, differs from B*5101 by a single nucleotide substitution that changes residue 171 from histidine to tyrosine. Residue 171, which is part of the alpha 2 helix, is believed to contribute directly to peptide interaction in the A pocket of the binding groove and is either histidine or tyrosine in all HLA-A, B, C heavy chains. Tyrosine 171 is shared by B*5102, B*3501, B*3502, and B*5301 and must be responsible for the serological cross-reactivities of these molecules not shared with B*5101. Stimulation of lymphocytes from a B*5101 positive donor with B*5102 positive cells failed to generate cytotoxic T cells with specificity for the difference between these molecules. However, one out of five clones of cytotoxic T cells raised against B*5101 failed to lyse targets expressing B*5102. Substitution of histidine for tyrosine at residue 171 affected recognition of HLA-B35-restricted human minor histocompatibility antigen-specific T cell clones.

Amino Acid Sequence↗
PubMed1990

Diagnosis of cardiac allograft rejection by the detection of circulating plasma cardiac myosin light chains.

Twenty adult male Japanese monkeys of the species Macaca fuscata were randomly paired and subjected to heterotopic cardiac transplantation performed by the Ono-Lyndsey method. Without immunosuppression, graft survival ranged between 8 and 27 days, with a mean survival of 14 days. Plasma cardiac myosin light chains were measured by radioimmunoassay, which showed transient increases in myosin levels just following transplantation. Three hearts showed high values at this period and stopped beating when the myosin levels decreased (type 1). The other 7 hearts showed low myosin values after transient increases and 5 of them were rejected with a preceding reincrease in the myosin levels (type 2). Pathological study revealed myocardial necrosis, perivascular cuffing of mononuclear cells and/or neutrophils and/or plasma cells in the type 1 hearts. Measurement of the plasma myosin light chain level was therefore revealed to be of great value in the monitoring of cardiac allograft rejection.

Animals↗