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Biomedical subjects

K Yoda

Publications and source records attributed to K Yoda.

At least 73 records · Page 4Linked to original sources
PubMed1994

[A case of vertebral metastasis revealed by incomplete spinal analgesia for cesarean section].

A 36-year-old woman was scheduled for Cesarean section under spinal anesthesia. She was a carrier of hepatitis-B-virus and diabetic. She was complaining of low back pain. Spinal anesthesia was performed in the left lateral decubitus position. Because lumbar puncture in the midline was difficult, left paramedian approach was tried. Then she began to complain of right leg pain. Another attempt was made at other site, but her pain was not relieved. After confirming drop of blood-tinged cerebrospinal fluid, 0.3% dibucaine 2.0 ml was injected. Sensory anesthesia was assessed by pin-prick, but anesthesia was not effective. Then epidural catheter was inserted at Th12-L1 using median approach. She received 1.0% lidocaine 15 ml. However, sensory anesthesia was insufficient (Th4-Th12). Therefore O2-N2O was administered in addition to regional anesthesia. After the delivery, she still complained of low back pain. Later examination revealed metastatic bone tumor of L2 from hepatoma. This case suggests that in a patient with such incomplete spinal or epidural anesthesia and neurological finding, vertebral metastatic tumor should be ruled out.

Adult↗
PubMed1992

Protein transport in the permeabilized cell of Schizosaccharomyces pombe.

We reconstituted a protein translocation-transport system composed of permeabilized spheroplasts (P-cells) of the fission yeast Schizosaccharomyces pombe and the precursor of alpha sex pheromone, prepro-alpha-factor of the budding yeast Saccharomyces cerevisiae. We found that P-cells prepared from the spheroplasts formed in 0.7M KCl as an osmotic stabilizer had the activity to transport pro-alpha-factor to the Golgi apparatus. Electron microscopic observations showed that membranes were preserved more intact in the P-cells prepared from the spheroplasts formed in 0.7M KCl than in 0.7M sorbitol. A glycoprotein of S. pombe contains galactose residues, and we detected incorporation of radiolabeled galactose residues into the anti-prepro-alpha-factor immunoprecipitable fractions in this S. pombe system, but not in the S. cerevisiae system. This paper reports that a heterologous system of in vitro protein transport was performed, and prepro-alpha-factor has the signals necessary for early steps of the transport in S. pombe.

Biological Transport↗
PubMed1992

Centromere protein B assembles human centromeric alpha-satellite DNA at the 17-bp sequence, CENP-B box.

We purified 15,000-fold from HeLa cell nuclear extract the centromere antigen that reacts specifically with the 17-bp sequence, designated previously as CENP-B box, in human centromeric alpha-satellite (alphoid) DNA by a two-step procedure including an oligonucleotide affinity column. The purified protein was identified as the centromere protein B (CENP-B) by its mobility on SDS-PAGE (80 kD), and reactivities to a monoclonal antibody raised to CENP-B (bacterial fusion protein) and to anticentromere sera from patients with autoimmune diseases. Direct binding by CENP-B of the CENP-B box sequence in the alphoid DNA has been proved using the purified CENP-B by DNA mobility-shift assay, Southwestern blotting, and DNase I protection analysis. The binding constant of the antigen to the CENP-B box sequence is 6 x 10(8) M-1. DNA mobility-shift assays indicated that the major complex formed between the CENP-B and the DNA contains two DNA molecules, suggesting the importance of the CENP-B/CENP-B box interaction in organization of higher ordered chromatin structures in the centromere and/or kinetochore. Location of DNA binding and dimerization domains in CENP-B was discussed based on the DNA mobility-shift assays performed with a protein fraction containing intact and partial cleavage products of CENP-B.

Autoantigens↗
PubMed1992

A human centromere protein, CENP-B, has a DNA binding domain containing four potential alpha helices at the NH2 terminus, which is separable from dimerizing activity.

The alphoid DNA-CENP-B (centromere protein B) complex is the first sequence-specific DNA/protein complex detected in the centromeric region of human chromosomes. In the reaction, CENP-B recognizes a 17-bp sequence (CENP-B box) and assembles two alphoid DNA molecules into a complex, which is designated complex A (Muro, Y., H. Masumoto, K. Yoda, N. Nozaki, M. Ohashi, and T. Okazaki. 1992. J. Cell Biol. 116:585-596). Since CENP-B gene is conserved in mammalian species and CENP-B boxes are found also in mouse centromere satellite DNA (minor satellite), this sequence-specific DNA-protein interaction may be important for some kind of common centromere function. In this study we have characterized the structure of CENP-B and CENP-B-alphoid DNA complex. We have shown by chemical cross-linking that CENP-B formed a dimer, and have estimated by molecular weight determination the composition of complex A to be a CENP-B dimer and two molecules of alphoid DNA. The DNA binding domain has been delimited within the NH2-terminal 125-amino acid region containing four potential alpha-helices using truncated CENP-B made in Escherichia coli cells. We have shown that CENP-B had sites highly sensitive to proteases and that the DNA binding domain was separable from the dimerizing activity by the proteolytic cleavage at 20 kD from the COOH terminus of the molecule. Thus, CENP-B may organize a higher order structure in the centromere by juxtaposing two CENP-B boxes in the alphoid DNA repeat through both the DNA-protein and protein-protein interactions.

Amino Acid Sequence↗
PubMed1992

TmrB protein, responsible for tunicamycin resistance of Bacillus subtilis, is a novel ATP-binding membrane protein.

tmrB is the gene responsible for tunicamycin resistance in Bacillus subtilis. It is predicted that an increase in tmrB gene expression makes B. subtilis tunicamycin resistant. To examine the tmrB gene product, we produced the tmrB gene product in Escherichia coli by using the tac promoter. TmrB protein was found not only in the cytoplasm fraction but also in the membrane fraction. Although TmrB protein is entirely hydrophilic and has no hydrophobic stretch of amino acids sufficient to span the membrane, its C-terminal 18 amino acids could form an amphiphilic alpha-helix. Breaking this potential alpha-helix by introducing proline residues or a stop codon into this region caused the release of this membrane-bound protein into the cytoplasmic fraction, indicating that the C-terminal 18 residues were essential for membrane binding. On the other hand, TmrB protein has an ATP-binding consensus sequence in the N-terminal region. We have tested whether this sequence actually has the ability to bind ATP by photoaffinity cross-linking with azido-[alpha-32P]ATP. Wild-type protein bound azido-ATP well, but mutants with substitutions in the consensus amino acids were unable to bind azido-ATP. These C-terminal or N-terminal mutant genes were unable to confer tunicamycin resistance on B. subtilis in a multicopy state. It is concluded that TmrB protein is a novel ATP-binding protein which is anchored to the membrane with its C-terminal amphiphilic alpha-helix.

Adenosine Triphosphate↗
PubMed1992

In vivo biotinylation of fusion proteins expressed in Escherichia coli with a sequence of Propionibacterium freudenreichii transcarboxylase 1.3S biotin subunit.

Biotinylation of fusion proteins in E. coli was studied using a sequence of Propionibacterium freudenreichii transcarboxylase 1.3S biotin subunit. As the biotinylation sequence, we examined two sequences: one was of amino acid residues [84-123] of 1.3S, a partial sequence containing a region from a conserved tetrapeptide (Ala-Met-Bct-Met) around the biotinyl lysine (Bct) to the carboxyl terminal; the other was of an almost entire sequence [18-123]. We constructed recombinant plasmids for fusion proteins of beta-galactosidase, of chloramphenicol acetyltransferase, and of alkaline phosphatase. We found the biotinylation in the [18-123] sequence fused to alkaline phosphatase.

Amino Acid Sequence↗
PubMed1992

Inhibition of protein translocation in permeabilized cells of Schizosaccharomyces pombe by puromycin.

To investigate protein translocation in eukaryotes, we reconstituted a protein translocation system using the permeabilized spheroplasts (P-cells) of the fission yeast Schizosaccharomyces pombe. The precursor of a sex pheromone of Saccharomyces cerevisiae, prepro-alpha-factor, was translocated across the endoplasmic reticulum (ER) of S. pombe posttranslationally, and glycosylated to the same extent as in the ER of S. cerevisiae. This suggested that the size of N-linked core-oligosaccharide in the ER of S. pombe is similar to that in S. cerevisiae. This translocation into the ER of S. pombe was inhibited by puromycin, but the translocation in the P-cells of S. cerevisiae was not inhibited. This difference in sensitivity to puromycin was due to the membrane but not the cytosolic fraction. Our results suggested that the translocation machinery of S. pombe was sensitive to puromycin and different from that of S. cerevisiae.

Cell Membrane Permeability↗
PubMed1991

Specificity of recognition sequence for Escherichia coli primase.

We have surveyed the frequency of each of 64 trinucleotide permutations at every nucleotide frame located from 1 to 15 nucleotides upstream of primer RNA-DNA transition sites mapped within a 1.5 kb region of the bacteriophage lambda genome and a 1.4 kb region of the Escherichia coli genome. We have demonstrated that in both systems initiation of DNA synthesis strongly correlates with a CAG sequence located 11 nucleotides upstream of the DNA start sites. Based on the examination of various reports of the priming reaction catalyzed by E. coli primase in vivo and in vitro, we propose that (i) E. coli primase itself recognizes a 3'GTC 5' sequence on the template strand, (ii) DnaB helicase releases the specificity of E. coli primase and, (iii) the consensus recognition sequence for E. coli primase associated with DnaB helicase is 3'PuPyPy 5'.

Bacteriophage lambda↗
PubMed1991

Comparative study on the cardio-respiratory change during prostaglandin E1-induced hypotension in the patients in the supine and prone position.

Prostaglandin E(1)-induced hypotension (25% reduction from the preadministration level in mean arterial pressure) was applied to thirteen patients. Eight patients among them were operated in the supine position (group I) and other five in the prone position (group II). The maintenance dose of PGE(1) was considerably lower in group II than in group I (0.067 micro g.kg(-1).min(-1) vs. 0.119 micro g.kg(-1).min(-1)). In group I, there was a significant increase in CI, with a significant decrease in SVRI and PVRI during PGE(1)-induced hypotension. Such a high dose of PGE(1) (0.119 micro g.kg(-1).min(-1)) was considered to have a direct dilating action on the systemic resistance bed as well as on the pulmonary vasculature. It was considered that the suppression of hypoxic pulmonary vasoconstriction could be a mechanism to increase venous admixture during PGE(1)-induced hypotension. In group II, there was no significant increase in CI, and no significant decrease in SVRI and PVRI. PGE(1)-induced hypotension can be safely applied to the anesthetized patients, but we should be careful to apply it to the patients in the prone position, because lower dose of PGE(1) can induce severe hypotension, which is not accompanied by the increase in CI as occurres in the patients in the supine position.

Journal Article↗
PubMed1991

A cytoskeleton-related gene, uso1, is required for intracellular protein transport in Saccharomyces cerevisiae.

The Saccharomyces cerevisiae mutant strains blocked in the protein secretion pathway are not able to induce sexual aggregation. We have utilized the defect of aggregation to concentrate the secretion-deficient cells and identified a new gene which functions in the process of intracellular protein transport. The new mutant, uso1, is temperature sensitive for growth and protein secretion. At the restrictive temperature (37 degrees C), uso1 mutant accumulated the core-glycosylated precursor form of the exported protein invertase in the cells. Ultrastructural study of the mutant fixed by the freeze-substitution method revealed expansion of the nuclear envelope lumen and accumulation of the ER at the restrictive temperature. Abnormally oriented bundles of microtubules were often found in the nucleus. The USO1 gene was cloned by complementation of the uso1 temperature-sensitive growth defect. DNA sequence analysis revealed a hydrophilic protein of 1790 amino acids with a COOH-terminal 1,100-amino acid-long alpha-helical structure characteristic of the coiled-coil rod region of the cytoskeleton-related proteins. These observations suggest that Uso1 protein plays a role as a cytoskeletal component in the protein transport from the ER to the later secretory compartments.

Amino Acid Sequence↗
PubMed1991

Metabolism of pravastatin sodium in isolated rat hepatocytes. II. Structure elucidation of the metabolites by n.m.r. spectroscopy.

1. The structures, including stereochemistry, of the two major metabolites of pravastatin sodium in an isolated rat hepatocyte system, i.e. the 4'a alpha-glutathione conjugate (CM-1) and the 3',5'-dihydrodiol (CM-2), were determined by one- and two-dimensional n.m.r. spectroscopy. 2. The structures of two synthetic pravastatin epoxides, possible precursors of the metabolites, were also established. 3. One of the synthetic epoxides, 4'a beta, 5' beta-epoxide was converted to the pravastatin metabolite, 4'a alpha-glutathione conjugate (CM-1) by a rat liver cytosol system and is proposed as the common metabolic intermediate between pravastatin sodium and the metabolites, CM-1 and CM-2.

Animals↗
PubMed1990

Decoupling technique for transmit coils in NMR spectroscopy and imaging.

A decoupling structure using an additional LC resonant configuration for NMR transmit coils is analysed and the probe sensitivity of the receive coil with the decoupled transmit coil is calculated using simple circuit models. An adjustment-free technique for the decoupling circuit under different loading conditions is proposed using the calculated results and demonstrated by experiments. The proposed method can simplify the probe operation.

Electricity↗
PubMed1990

Production and secretion in Escherichia coli of hepatitis B virus pre-S2 antigen as fusion proteins with beta-lactamase.

The diagnostically important surface antigen pre-S2 of hepatitis B virus was produced in large amounts in the periplasmic space of Escherichia coli. The DNA fragments (pre-S2) coding the pre-S2 antigen were tandemly duplicated or triplicated and ligated in the same reading frame to a fragment containing the promoter and the signal sequence of the alkaline phosphatase-coding gene (phoA) of E. coli. Further, a DNA fragment (bla) coding mature beta-lactamase was joined to the region coding the C terminus of the pre-S2 repeat to stabilize the gene product. Upon induction of the phoA-(pre-S2)3-bla fusion gene, the fusion protein was produced at up to 30% of the total cellular protein. Fractionation of the cellular components and trypsin accessibility of the product showed that the antigen was secreted in the periplasm and formed inclusion bodies there. The signal sequence of alkaline phosphatase was found to be correctly processed in E. coli.

Amino Acid Sequence↗