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Biomedical subjects

T Oda

Publications and source records attributed to T Oda.

At least 343 records · Page 19Linked to original sources
PubMed1994

DNA binding properties of recombinant human mitochondrial transcription factor 1.

Recombinant mitochondrial transcription factor 1 (r-mtTF1) was overproduced in Escherichia coli, and purified to near homogeneity by DNA affinity chromatography. Binding affinities of r-mtTF1 to the light strand promoter (LSP) and heavy strand promoter (HSP) of human mitochondrial DNA and a non-promoter fragment derived from pUC vector were quantitatively measured by electrophoretic mobility shift assay. The order of the affinities for these DNAs estimated by competition experiments was LSP > HSP = pUC, which was essentially the same as that of transcriptional activity from each promoter in vitro. Recombinant mtTF1 bound more tightly to supercoiled or relaxed DNA than to linear DNA, moreover to single-stranded DNA with the same affinity for linear DNA. The results suggest that the mechanism of activation of HSP by mtTF1 is different from that of LSP, and that multiple binding of mtTF1 to mitochondrial DNA, in a non-specific manner, may significantly participate in activation of transcription from HSP and replication of mitochondrial DNA.

DNA, Mitochondrial↗
PubMed1994

Alterations of the cadherin-catenin cell adhesion system in cancers.

The E-cadherin-mediated cell adhesion system acts as an "invasion suppressor" system, which is widely considered to be inactivated when the expression of E-cadherin is reduced and/or heterogeneous. To further investigate the molecular mechanisms responsible for dysfunction of this system in cancers, we examined human carcinoma cell lines lacking tight cell-cell adhesion. In KATO-III, established from stomach cancer, a point mutation of the E-cadherin gene resulted in a mRNA splicing error and markedly reduced E-cadherin expression. In another stomach cancer cell line, MKN 45, an 18-bp deletion of the E-cadherin gene caused a mRNA splicing error and a 4-amino-acid deletion, which was considered to alter the conformation around the key Ca(2+)-binding motif. In these two cell lines, the wild-type allele of the E-cadherin locus, which was assigned to chromosome 16q, was lost. Also in vivo, we found mutation of E-cadherin in breast cancers, where allele loss on chromosome 16 has frequently been reported. Thus, dysfunction of E-cadherin could be caused by a combination of the loss of one allele and a mutation in the remaining allele. Homologous deletion of part of the alpha-catenin gene, resulting in markedly reduced expression, was observed in a human lung cancer cell line, PC9. Recently, we also found mutations of beta-catenin in human carcinoma cell lines. These findings indicate the possible involvement of genetic abnormalities of various components in inactivation of the E-cadherin-mediated "invasion suppressor system" in cancers.

Binding Sites↗
PubMed1993

Horseshoe crab coagulation factor B. A unique serine protease zymogen activated by cleavage of an Ile-Ile bond.

Horseshoe crab factor B is an intracellular serine protease zymogen involved in the bacterial endotoxin-responsive hemolymph coagulation cascade. cDNAs for factor B were isolated utilizing a polymerase chain reaction product using two primers derived from the partial amino acid sequence. The cloned cDNA of 1928 base pairs encoded 400 amino acid residues of factor B precursor. The first 23 amino acid residues constitute a presumed prepropeptide that may be processed by both a signal peptidase and a processing protease, similar to mammalian vitamin K-dependent protease precursors. The mature protein consists of 377 amino acids with a calculated molecular mass of 40,570 Da. The overall structure is highly homologous to that of limulus proclotting enzyme (35.9% identity), the substrate for active factor B in the cascade. Like the proclotting enzyme, mature factor B is composed of an amino-terminal "clip"-like domain and a carboxyl-terminal serine protease domain homologous to that of human plasma prekallikrein (36.5%). Internal sequences encode a unique activation peptide. Surprisingly, the cleavage sites of the zymogen factor B for activation by limulus active factor C were found to be an Arg-Ser and an Ile-Ile bond, the latter of which has not been found in any other protease zymogens. These cleavages result in the release of the activation peptide, which consists of 21 residues with a carboxyl-terminal isoleucine. These results indicate that the intracellular clotting system of the limulus hemocyte, like mammalian plasma clotting cascade, proceeds with the sequential activation of three serine protease zymogens: factor C, factor B, and proclotting enzyme.

Amino Acid Sequence↗
PubMed1993

Hereditary nodular heterotopia accompanied by mega cisterna magna.

This is the first report of hereditary nodular heterotopia accompanied by mega cisterna magna. Magnetic resonance imaging documented multiple bilateral subependymal nodules, which were isointense to gray matter. This disease entity is considered a dominant trait, since the mother and two daughters, half-sisters, were affected.

Adult↗
PubMed1993

Cloning of the human alpha-catenin cDNA and its aberrant mRNA in a human cancer cell line.

Cadherin and catenin compose cell adhesion complex and are indispensable for tight cell-cell adhesion. Dysfunction of this adhesion complex causes dissociation of cancer cells from primary tumor nodules, thus possibly contributing to cancer invasion and metastasis. In this report, we present the human alpha-catenin sequence. Human alpha-catenin showed extensive homology with that of mouse, i.e., 91.8% and 99.3% at the nucleic acid and amino acid levels, respectively, indicating that this molecule has been evolutionarily conserved in mammals. Characterization of the mRNA sequence of alpha-catenin in PC9 was also carried out, and two distinct abnormal sequences, i.e., one of 957 bp deletion resulting in a 319-amino-acid deletion and another of 761 bp deletion resulting in a frameshift, were identified. These deletions were probably produced by an error of RNA splicing, presenting one possible mechanism for the loss of intact alpha-catenin expression.

Animals↗
PubMed1993

Cerulenin inhibits the cytotoxicity of ricin, modeccin, Pseudomonas toxin, and diphtheria toxin in brefeldin A-resistant cell lines.

We have found that cerulenin, an antibiotic that inhibits de novo fatty acid and cholesterol biosynthesis and fatty acylation of proteins, strongly inhibited the cytotoxicity of ricin, modeccin, Pseudomonas toxin, and diphtheria toxin in a brefeldin A (BFA)-resistant mutant of Vero cells (BER-40). The protective effect of cerulenin against ricin was also observed in two other BFA-resistant cell lines, Madin-Darby canine kidney, and PtK1 cells. In contrast to BER-40 cells, no significant effect of cerulenin was observed in Vero cells. Cerulenin did not affect the binding of ricin to the cell-surface receptors, but reduced significantly the internalization of ricin in BER-40 cells; no effect of cerulenin on the binding or internalization of ricin was observed in Vero, PtK1, and Madin-Darby canine kidney cells. Endocytic uptake of fluid-phase markers such as horseradish peroxidase and lucifer yellow was inhibited by cerulenin in BER-40 cells, but the endocytosis of transferrin via the coated pit/coated vesicle pathway was slightly increased. Cerulenin inhibited the degradation and excretion of ricin in BER-40 cells, and this effect of cerulenin was not observed in Vero cells. Furthermore, cerulenin inhibited the bulk protein secretion in a dose-dependent manner, with BER-40 cells being more susceptible than Vero cells. These results suggest that in addition to its effect on endocytosis, cerulenin interferes with the intracellular trafficking or processing of toxin molecules, and the vesicle transport system in BER-40 cells appears to be cerulenin-sensitive. Since addition of fatty acids and cholesterol did not reverse the effects of cerulenin, the protective effect of cerulenin against protein toxins is not due to an inhibition of de novo fatty acids and cholesterol biosynthesis.

ADP Ribose Transferases↗
PubMed1993

Automated high-performance liquid chromatographic determination of hydroxylysylpyridinoline and lysylpyridinoline in urine using a column-switching method.

An on-line urine clean-up system was developed for the simultaneous determination of free and total pyridinoline, hydroxylysyl-pyridinoline (HP) and lysylpyridinoline (LP) by high-performance liquid chromatography (HPLC) using a column-switching technique. The method is based on a combination of gel permeation chromatography (GPC) and ion-pair reversed-phase HPLC. In the GPC column, pyridinoline is preseparated from endogenous urinary substances with 0.03 M heptafluorobutyric acid (HFBA) as the mobile phase. After column switching, the eluate fraction containing pyridinoline is further separated by ion-pair chromatography using an octadecylsilica (ODS) column with 0.03 M HFBA-acetonitrile (81:19) as the mobile phase. The detection limits were 36 and 44 pmol/ml for free and total HP, respectively, and 44 pmol/ml for both free and total LP at a signal-to-noise ratio of 3. The coefficients of variation for free and total pyridinoline were 1.5 and 3.5%, respectively. The determination of one sample including the clean-up is completed within 25 min. This system is precise and is useful for the determination of pyridinoline in large amounts of urine. The usefulness of pyridinoline as a biomedical marker for bone resorption was also examined.

Amino Acids↗
PubMed1993

Injection of anti-neuropeptide Y gamma-globulin into the hypothalamic paraventricular nucleus decreases food intake in rats.

The effect of immunoneutralization of hypothalamic neuropeptide Y (NPY) on food intake was examined to clarify the involvement of NPY in the control mechanism of feeding behavior. Injection of anti-NPY gamma-globulin into the bilateral hypothalamic paraventricular nuclei of 24-h food-deprived rats significantly inhibited food intake for 1 h after the injection compared with rats that received normal rabbit gamma-globulin. This result suggests that NPY in the paraventricular nucleus plays a role in stimulating feeding behavior.

Animals↗
PubMed1993

Involvement of the Golgi region in the intracellular trafficking of cholera toxin.

The intracellular pathway following receptor-mediated endocytosis of cholera toxin was studied using brefeldin A (BFA), which inhibited protein secretion and induced dramatic morphological changes in the Golgi region. In both mouse Y1 adrenal cells and CHO cells, BFA at 1 micrograms/ml caused a 80-90% inhibition of the cholera toxin (CT)-induced elevation of intracellular cAMP. The inhibition of the cytotoxicity of CT by BFA was also observed in a rounding assay of Y1 adrenal cells. The inhibition of CT cytotoxicity by BFA was dose dependent, with the ID50 value similar to the LD50 of BFA in Y1 adrenal cells. Binding and internalization of [125I]-labeled cholera toxin in Y1 adrenal cells was not affected by BFA. Unlike the BFA-sensitive cell lines such as Y1 adrenal and CHO cells, BFA at 1 micrograms/ml did not inhibit the cytotoxicity of CT in PtK1 cells, of which the Golgi structure was BFA-resistant. These results strongly suggest that a BFA-sensitive Golgi is required for the protection of CT cytotoxicity by BFA. In contrast, elevation of the intracellular cAMP by forskolin, which acts directly on the plasma membrane adenylate cyclase, was not affected by BFA. These observations indicate that the intoxication of target cells by CT requires an intact Golgi region for its intracellular trafficking and/or processing. In this respect, CT shares a common intracellular pathway with ricin, Pseudomonas toxin, and modeccin, even though their structures and modes of action are very different.

Animals↗
PubMed1993

Posture affects motion coupling patterns of the upper cervical spine.

Measurements of motions of the cervical spine are used to help diagnose the problems of clinical instability due to degenerative changes and trauma. For a better interpretation of the three-dimensional motions of the upper cervical spine, knowledge of the effects of posture on these motions is necessary. Seven fresh human cadaveric C0-C3 spinal specimens were utilized. Each specimen was put in three distinct sagittal plane postures: full flexion, neutral, and full extension. At each posture, two load types were applied: left and right axial torques, and left and right lateral bending moments up to 1.5 Nm. The resulting three-dimensional relative motions of C0-C1 and C1-C2 were measured, with use of nonconstraining stereophotogrammetry, in the form of load-displacement curves. We found that the curves were nonlinear. The most dramatic change due to modification in posture was found in coupled sagittal plane rotation, which changed from extension at extended posture to flexion at flexed posture at both levels and in response to both load types. For the axial torque, the main axial rotation and coupled lateral bending changed little with posture. For the lateral bending moment, the main lateral bending rotation and coupled axial rotation decreased; the latter changed direction at C1-C2 as the spine was put into flexed posture. The motions for the right and left load applications generally were mirror images, except for the coupled sagittal plane rotations, which did not change with the direction of the load.

Adult↗
PubMed1993

Characterization and sequence analysis of rat serine:pyruvate/alanine:glyoxylate aminotransferase gene.

We have reported the isolation of genomic clones encoding serine:pyruvate aminotransferase (SPT; also named alanine:glyoxylate aminotransferase, AGT) (T. Oda, T. Funai, and A. Ichiyama, 1990, J. Biol. Chem. 265: 7513-7519). These clones contained the entire SPT/AGT gene of 10 kb. In this work, we characterized this gene. The SPT/AGT gene consists of 11 exons, and the exon-intron boundaries have typical splice donor and acceptor sequences. Determination of the nucleotide sequence up to -1.25 kb from the transcription initiation site revealed the presence of many putative cis elements, some of which may explain the transcriptional regulation of the SPT/AGT gene by glucagon and glucocorticoid. The nucleotide sequence around the 5' flanking region of the rat SPT/AGT gene and the whole gene organization were compared with those of the human SPT/AGT gene. No obvious similarities were observed in the 5' flanking region up to -1.25 kb from the initiation site of the gene, but exons 2 to 10 of the rat and human genes have identical sizes and show high similarities.

Alanine Transaminase↗
PubMed1993

Recovery of the Frank-Starling mechanism by coenzyme Q10 in patients with load-induced contractility depression.

Load-induced contractility depression, in which supernormal left ventricular ejection fraction and contractility at rest decrease by added afterload, is most often found in children with mitral valve prolapse who have symptoms. Patients have high ventricular end-diastolic pressure at rest, which is further increased by afterload challenge. The Frank-Starling mechanism may be maximally mobilized with high preload even at rest to compensate for the intrinsically depressed inotropic state. Therefore, preload reserve may be easily exhausted due to afterload addition. We aimed to determine left ventricular end-diastolic fiber length, stroke work, and contractility before and during handgrip by echocardiograms to obtain evidence for the Frank-Starling mechanism in patients and controls, including patients treated with coenzyme Q10. The subjects were divided into four groups, each consisting of 30 children aged 6-16 years: group 1, normals; group 2, patients; group 3, the same patients as in group 2 after coenzyme Q10 therapy; and group 4, patients with asymptomatic mitral valve prolapse. Baseline values and percentage increases in systolic blood pressure, heart rate, and left ventricular wall stress showed no differences among the groups. Only in group 2 were the percentage increase in ejection fraction, fiber shortening velocity, contractility, and end-diastolic dimension strongly negative, despite supernormal baseline levels. In other groups, these were significantly positive, without intergroup differences. We conclude that in the heart with load-induced contractility depression, the Frank-Starling mechanism deviates from normal. The normal Frank-Starling mechanism was recovered due to coenzyme Q10, which may improve disturbed bioenergetic function at the molecular level.

Adolescent↗
PubMed1993

Concurrent ovarian serous carcinoma and osteogenesis imperfecta.

Because epithelial malignancies in patients with osteogenesis imperfecta are rare, it has been postulated that these patients may have "cancer-protection". A case of stage III b ovarian serous carcinoma in a woman with congenital osteogenesis imperfecta is now presented and discussed.

Adult↗
PubMed1993

Effects of (+)-, (-)- and (+/-)-indenestrols A and B on microtubule distribution and cytotoxicity in Chinese hamster V79 cells.

We have reported that (+)-, (-)- and (+/-)-indenestrols A and B (IA and IB respectively) inhibit the polymerization of microtubule proteins isolated from porcine brain in vitro. In this study, the effects of (+)-, (-)- and (+/-)-IA and IB on the relative plating efficiency, chromosome number and cellular microtubular architecture of Chinese hamster V79 cells, detected with a fluorescent anti-tubulin antibody, were investigated. The results indicated that the effect of (+/-)-IA was similar to that of diethylstilbestrol and that of (+/-)-IB was greater than that of (+/-)-IA. We also determined the effects of the optically active IA and IB isomers and found that the rank order of cytotoxic activity of the IA and IB series was: (-)-IA > (+/-)-IA > (+)-IA and (+/-)-IB > or = (-)-IB > (+)-IB. Furthermore, we studied the intracellular disturbance of microtubule formation induced by these compounds and found that (-)-IA had by far the greatest disruptive effect.

Aneuploidy↗