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Biomedical subjects

Y Ohba

Publications and source records attributed to Y Ohba.

At least 145 records · Page 8Linked to original sources
PubMed1992

Cyclin-dependent kinase 2 (cdk2) in the murine Cdc2 kinase TS mutant.

Kinases of the mammalian cdc2 family including cdk2 (cyclin-dependent kinase 2) are thought to be involved in both the G2/M transition and DNA replication. To investigate the role of cdc2 kinase and cdk2 in cell cycle progression, murine tsFT210 cells bearing a temperature-sensitive cdc2 mutation were used. These kinases were purified by column chromatography, using a peptide with the consensus phosphorylation site of cdc2 kinase as the substrate. In this mutant, cdc2 kinase activity was temperature sensitive and cdk2 activity was not. At the restrictive temperature, the mutant was only arrested in the G2 phase and not in the G1-S phase, suggesting that cdk2 did not compensate for cdc2 kinase at the G2/M transition but did function at the G1-S phase. This suggestion was supported by the finding that transfection of cdk2 cDNA did not improve the growth of the mutant cell line at the restrictive temperature, although transfection of cdc2 cDNA did.

Animals↗
PubMed1992

Hemoglobin Kansas found in a patient with polycythemia.

A 62-year-old woman, long suspected of having heart disease, was admitted to our hospital for thorough examination. Her hemoglobin level was 17.7 g/dl and her 2.3-DPG level was 8.90 microM/ml RBC. The patient proved to have polycythemia, hemoglobin Kansas, and diabetes mellitus. To our knowledge, this is the third case of hemoglobin Kansas in the world.

2,3-Diphosphoglycerate↗
PubMed1992

A temperature-sensitive CHO-K1 cell mutant (tsTM13) defective in chromosome decondensation and spindle deconstruction in M phase.

A temperature-sensitive CHO-K1 cell mutant, tsTM13, exhibited a delayed cell cycle progression from metaphase to telophase at a nonpermissive temperature and was finally arrested from anaphase to telophase. Metaphase chromosomes were overcondensed and chromosome disjunction in anaphase was uncoordinated. In telophase, sister chromatids were segregated and cytokinesis was completed, but chromosome structure remained in a condensed state and the spindle was not deconstructed. The level of phosphorylation of histones H1 and H3 remained high in the later stages of mitosis and the activity of histone H1 kinase was also maintained at a high level. These results strongly suggest that the pleiotropic defects of tsTM13 cells in mitosis are associated with a lack of inactivation of activated histone H1 kinase.

Amino Acid Sequence↗
PubMed1992

Autocrine role of insulin-like growth factor (IGF)-I in a human thyroid cancer cell line.

An established cell line (TC-cell, clone 78) derived from human thyroid papillary cancer cells was investigated for production of peptide growth factors. The cells had specific binding sites for insulin-like growth factor-I (IGF-I) and responded to this growth factor with increased proliferation. Culture medium conditioned by TC cells was found to contain insulin-like growth factor (IGF)-I and IGF-binding protein(s). Furthermore, reverse transcription-polymerase chain reaction revealed expression of IGF-I mRNA. When monoclonal antibody to IGF-I receptors (alpha IR3) was added, the growth of TC cells cultured in serum-free medium was significantly reduced. The growth rate of the cells was restored when the antibody was removed from the medium. These results strongly suggest that TC cells produce IGF-I, which is involved in the regulation of their own growth.

Carcinoma, Papillary↗
PubMed1992

Intrapair differences of physical aging and longevity in identical twins.

The genetic and environmental contributions to physical aging (hair graying, balding, presbyopia) and longevity (age at death) were examined by within-pair comparison in monozygotic (MZ) and dizygotic (DZ) twins in later adulthood. Physical aging was investigated on 135 pairs of adult twins aged over 50. Hair graying and hair loss (baldness) showed significantly higher rates of concordance in the MZ twins than in the DZ twins. The intrapair difference of the degree of hair graying was negligible in 79%, slight in 15% and striking in 5% among the MZ pairs; while negligible in 40%, slight in 50% and striking in 10% among the DZ pairs. The intrapair difference of the degree of hair loss was negligible in 92%, slight in 8% (and striking in none) among the MZ pairs; while negligible in 69%, slight in 25% and striking in 6% among the DZ pairs. The age at onset of presbyopia showed a slightly higher rate of concordance in the MZ than in the DZ pairs. Longevity (age at death) was surveyed on 184 pairs of twins who died at over 40 years of age. The intrapair difference of longevity was 6.65 +/- 5.6 years (maximum 18.0; minimum 0.04) in the MZ pairs, and 8.66 +/- 7.2 years (maximum 18.6; minimum 2.9) in the DZ pairs. The MZ pairs showed a slightly smaller within-pair difference of longevity than the DZ pairs.

Aged↗
PubMed1992

Risk factors for cognitive aging in adult twins.

Monozygotic (MZ) and dizygotic (DZ) twins in later adulthood were studied in order to examine genetic and environmental contributions to the decline of cognitive performance. In this study, 118 twin pairs took a comprehensive medical examination at a university hospital. Cognitive function was measured by the Wechsler Adult Intelligence Scale (WAIS). The intraclass correlation coefficients on Digit Span (D) and Digit Symbol (DS) subtests of the WAIS did not show any significant difference between MZ and DZ twins although Block Design (BD) showed a significant difference. The values of the intraclass correlation coefficients were mostly around 0.5 and showed significant within-pair similarity of test scores. The mean score of D, DS and BD declined with advancing age. The intraclass correlation coefficients for D, DS and BD were around 0.2 in the MZ twins reared apart, and around 0.6 in the MZ twins reared together. These results indicated a significant environmental influence on cognitive aging in later adulthood.

Aged↗
PubMed1992

[A case of Vibrio cholerae non-O1 septicemia with liver cirrhosis].

A case of Vibrio cholerae non-O1 septicemia is described in this paper. A 45-year-old male with a three year history of liver cirrhosis, was admitted to our division with hematemesis, abdominal pain, high fever and a loss of consciousness. Three days before onset of symptoms, he traveled to Ishigaki Island and ate a raw lobster. Two days after, his temperature rose to 39.7 degrees C and the blood pressure dropped to 36/- mmHg. By endoscopic examination, an ulcer was found in the stomach, and the bleeding was stopped by electrical coagulation. Blood culture showed growth of V. cholerae non-O1. The organism was found to be sensitive to OFLX, CZX, MINO, LMOX and CP. Although DIC, infections of fungus and MRSA occurred as complications, he recovered by adequate procedures. Subsequently, he left this division after eight weeks. There are various reports related to V. cholerae non-O1 septicemia in foreign countries, but few cases have been reported in Japan. And these cases had severe underlying diseases such as leukemia and liver cirrhosis.

Bacteremia↗
PubMed1992

Concomitant increase in putrescine incorporation with transferrin uptake into rat reticulocytes.

Concomitant increase in putrescine incorporation with transferrin uptake into rat reticulocytes was found. [14C]Putrescine incorporation occurred in the presence of transferrin at 37 degrees C. The subcellular distribution of incorporated [14C]putrescine showed that the incorporation in the plasma membrane time dependently increased. Both 125I-labeled transferrin uptake and [14C]putrescine incorporation decreased when ethylene glycol bis(2-aminoethyl ether)-N,N,N',N'-tetraacetic acid was added, while it increased with the addition of A23187.

Animals↗
PubMed1992

[A case of amnesic stroke caused by left hippocampal infarction].

A 78-year-old woman was admitted to our hospital because of acute onset amnesia in March 1991. Neurological examination revealed right homonymous hemianopsia and clumsiness of the right hand. Magnetic resonance imaging (MRI) demonstrated abnormal intensity areas in the left hippocampus, parahippocampal gyrus, fimbria of the hippocampus and the occipital lobe. Immediate memory and long-term memory were relatively well-preserved, but short-term memory was severely disturbed. Her memory disturbance persisted for more than 9 months and she eventually developed an "amnesic stroke". According to the MRI findings, the "amnesic stroke" was produced by infarction of the left hippocampus, parahippocampal gyrus and fimbria of the hippocampus. We emphasized that in this case an "amnesic stroke" was caused by infarction of the left hippocampal lesions.

Aged↗
PubMed1992

A family case of beta-thalassemia minor and hemoglobin Queens: alpha 34 (B15) Leu-Arg.

We report a Korean family case of beta-thalassemia minor and Hb Queens. This is the first case report of Hb Queens in Korea. A 43-year-old male and his four family members had beta-thalassemia minor which is very rare in Korea. Incidentally, an alpha chain variant with a high isoelectric point was also found in two other family members without clinical problems and was finally identified as alpha 34 (B15) Leu-Arg or Hemoglobin Queens.

Adult↗
PubMed1992

cdc2-like kinase is associated with the retinoblastoma protein.

The growth-suppressive activity of the retinoblastoma (RB) protein is suggested to be regulated by phosphorylation. In studies on the kinase that phosphorylates the RB proteins, we have previously found that RB proteins can be phosphorylated by purified cdc2 kinase. In this study, we noted that RB proteins immunoprecipitated from human cell lysates are weakly phosphorylated in the absence of purified cdc2 kinase. Immunoblot analysis showed the presence of p34cdc2 in the immunoprecipitates with anti-RB monoclonal antibody. In addition, the coprecipitated kinase was found to have the same substrate specificity as cdc2 kinase. The associated kinase activity was particularly high in cells arrested in G1/S and S phase by aphidicolin. Furthermore, RB proteins were shown to be phosphorylated in nuclear extracts by some endogenous cdc2-like kinase(s). These results suggest that cdc2-like kinase is the main kinase for phosphorylation of RB proteins in vivo.

Amino Acid Sequence↗
PubMed1991

Microtubule destabilization by cdc2/H1 histone kinase: phosphorylation of a "pro-rich region" in the microtubule-binding domain of MAP-4.

Microtubule-associated protein-4 (MAP-4), a major MAP in proliferating cells, consists of a microtubule-binding domain and a projection domain protruding from the microtubule wall. The former contains a Pro-rich region and an assembly-promoting (AP) sequence region which is common to the neuron-specific MAPs, MAP-2 and tau1. In this paper, we describe the phosphorylation of the Pro-rich region of MAP-4 and the suppression of its assembly-promoting activity by cdc2/H1 histone kinase. This inactivation of MAP-4 may cause disassembly of the interphase microtubular network at the end of the G2 phase of the cell cycle.

Amino Acid Sequence↗