Biomedical subjects

O Koiwai

Publications and source records attributed to O Koiwai.

59 records · Page 4Linked to original sources

PubMed1979

Studies on bacterial chemotaxis. IV. Interaction of maltose receptor with a membrane-bound chemosensing component.

Highly purified maltose receptor of Escherichia coli was bound to Sepharose 4B via a long spacer and affinity chromatography was performed to isolate the membrane-bound proteins having affinity for the maltose receptor. The experiments were carried out either in the presence of maltose or in the absence of maltose and the proteins absorbed on the mattix were identified by two-dimensional gel electrophoresis. The results showed that the maltose receptor interacted with the product of tar gene, one of the methyl-accepting chemotaxis proteins, only in the presence of maltose.

Cell Membrane↗

PubMed1976

The primary structure of non-initiator methionine transfer ribonucleic acid from Bakers' yeast. I. Purification and complete digestion with ribonuclease T1 and pancreatic ribonuclease A.

The methionine acceptor activity of a crude tRNA from bakers' yeast was resolved into two peaks (I and II) by column chromatography on DEAE-Sephadex A-25 with a 1 M phosphate system. Methionine tRNA from peak II was not formylated by E. coli methionyl-tRNA transformylase [EC 2.1.2.9.] after being charged with methionine, whereas that from peak I was formylatable under the same conditions. A substantial amount of unlabelled methionine tRNA, tRNAMetm, was highly purified from the peak II fraction by successive chromatographic procedures. The purified tRNAMetm was digested with pancreatic ribonuclease A [EC 3.1.4.22] and ribonuclease T1 [EC 3.1.4.8]. The digestion products were isolated into individual components and completely sequenced. The results of sequence analysis of the two RNase digests were in good agreement and indicated that the chain length of this tRNA is 76, including 13 modified nucleotides. These oligonucleotide fragments can be constructed into a unique total sequence, assuming a few conventional features of clover leaf structure for the tRNA was established by analyses of partial digestion products with RNase T1, as reported in the accompanying paper.

Base Sequence↗

PubMed1976

The primary structure of non-initiator methionine transfer ribonucleic acid from Bakers' yeast. II. Partial digestion with ribonuclease T1 and derivation of the complete sequence.

Large oligonucleotides obtained from partial RNase T1 digestion of tRNAMetm from bakers' yeast (S. cerevisiae, strain Y 185) were isolated by chromatographic procedures and sequenced. The complete sequence of the tRNAMetm was established from the results of this partial digestion, together with those of the complete RNase T1 and A [EC 3.1.4.8 and 22] digestions of tRNAMetm reported in the preceding paper. The structure of this tRNAMetm was arranged into a clover leaf comparable with those of other tRNAMet species including bakers' yeast initiator tRNA.

Base Sequence↗

PubMedDate not supplied

Novel leukemic lymphoma with probable derivation from immature stage of natural killer (NK) lineage in an aged patient.

A 66-year-old male patient was admitted with dyspnea; physical examination revealed petechiae and systemic lymphadenopathy. Laboratory findings showed leukemia. The blasts in the peripheral blood were negative for cytochemical myeloperoxidase, and had condensed nuclear chromatin with a nucleolus. The histological diagnosis of the biopsied neck lymph node was lymphoblastic lymphoma. The leukemia cells expressed CD2, CD6, CD7, CD13low, CD56, beta chain of IL-2 receptorlow (IL-2R beta), and HLA-DR antigens, but not other pan-T (CD5, CD3, CD4, and CD8); pan-B (CD10, CD19, CD20, and CD24); natural killer (NK) (CD16, CD57); or myeloid (CD33) antigens. Electronmicroscopy revealed convoluted nuclei with conspicuous nucleoli and peripherally condensed heterochromatin. Membrane-bound granules containing an electron dense matrix were observed in the cytoplasm, indicating the NK cell nature of the neoplastic cells. While terminal deoxynucleotidyl transferase (TdT) and cytoplasmic CD3 were not detected by immunofluorescence on fixed smears, Northern blot analysis revealed the gene expression of CD3 epsilon, CD3 zeta, and TdT. Gene rearrangement analysis revealed that the beta, gamma, and delta chains of T-cell receptor (TCR) and immunoglobulin heavy chain (IgH) were of germline genotype. While the overall interpretation of the phenotype and genotype was difficult, the derivation of an immature stage of NK lineage was strongly suggested, based predominantly on the electronmicroscopic features. Despite initially successful chemotherapy, the patient died 14 months after initial presentation.

Aged↗

PubMedDate not supplied

Strong, long-term transgene expression in rat liver using chicken beta-actin promoter associated with cytomegalovirus immediate-early enhancer (CAG promoter).

For successful gene therapy in hepatic enzyme deficiencies, it is essential to use promoters that can maintain strong transcriptional activity for the long term in the liver. Using Gunn rats, a model animal for Crigler-Najjar syndrome type I, the long-term transcriptional function of the CAG promoter (a combination of chicken beta-actin promoter and cytomegalovirus immediate-early enhancer) was evaluated in the rat liver. We constructed a plasmid pCAGGHUGT, containing expression cassettes of human bilirubin UDP-glucuronosyltransferase (BUGT) and hygromycin phosphotransferase, under the control of the CAG promoter and murine phosphoglycerate kinase promoter, respectively. Conditionally immortalized Gunn rat hepatocytes (IGRH), which had been established using mutant SV40 large T antigen ((TS)T), were transfected with pCAG-GHUGT. A stably transfected clone IGRHUGT, expressing a high level of BUGT, was obtained after selection with hygromycin. At 33 degrees C, the cells doubled in number in approximately 72 h; however, at 37 degrees C, cell proliferation stopped, indicating that the characteristic of temperature-dependent proliferation was retained in this clone. Ten million cells were injected into the spleen of syngeneic Gunn rats five times at 10-day intervals. Serum bilirubin levels were reduced by 45-50% at 70 days after the first transplantation and remained so throughout the duration of the study (120 days). These results suggested that the CAG promoter was able to maintain strong transcriptional activity in rat liver for at least 120 days.

Actins↗