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Y Oka

Publications and source records attributed to Y Oka.

At least 361 records · Page 20Linked to original sources
PubMed1992

Two glucose transporter isoforms are sorted differentially and are expressed in distinct cellular compartments.

Rat GLUT4 (adipocyte/muscle-type glucose transporter) was expressed in two fibroblastic cell lines, Chinese hamster ovary (CHO) cells and 3T3-L1 fibroblasts, under the control of the methallothionein I promoter. Although immunoblotting with a GLUT4-specific anti-peptide antibody demonstrated that the amount of GLUT4 expressed was comparable with that in 3T3-L1 adipocytes and rat adipose tissues, no increase in 2-deoxy-D-glucose uptake was observed in the basal state in fibroblasts. Immunocytochemical studies showed that the expressed GLUT4 appeared to be localized in a specific region in the cytoplasm. These results were in marked contrast to those obtained in CHO cells expressing GLUT1 (HepG2/erythrocyte-type glucose transporter) using the same expression vector. In this case the expressed GLUT1 protein appeared to reside mainly on the plasma membranes, and a significant increase in glucose uptake was observed. Although insulin increased glucose uptake in CHO cells and 3T3-L1 fibroblasts as well as in the cells expressing rat GLUT4, an increment due to insulin above basal values was small, at most 2-fold, and no significant differences were observed in insulin-stimulated glucose uptake between transfected and parental cells. In addition, no apparent differences in the subcellular distribution of expressed GLUT4 were observed between the insulin-stimulated and the basal state. These results indicate that in fibroblastic cell lines GLUT1 and GLUT4 proteins are sorted in a different fashion, and the expression of GLUT4 protein per se is not enough to produce a large insulin-induced increase in glucose transport activity such as that observed in rat adipocytes and 3T3-L1 adipocytes. Thus unidentified aspects of the cellular environment which are present in the adipocytes but not in fibroblastic cell lines may be required for a large insulin-induced increase in glucose transport activity to be observed.

Adipose Tissue↗
PubMed1992

Protease inhibitors (gebexate mesylate and ulinastatin) stimulate intracellular chemiluminescence in human neutrophils.

The effect of protease inhibitors on the intracellular production of free radicals was investigated by measuring chemiluminescence (CL) elicited from phagocytosed luminol-bound microspheres (Lumispheres) in human neutrophils stimulated with formylmethionyl-leucyl-phenylalanine (fMLP), interleukin-8 (IL-8), phorbol 12-myristate 13-acetate, or diacylglycerol. Both gabexate mesylate (Foy) and ulinastatin (Miraclid), urinary trypsin inhibitor, increased intracellular CL in a dose dependent manner. Compared to control buffer without protease inhibitor, gabexate mesylate (322 micrograms/ml) caused about a 10-fold increase in intracellular CL in stimulated neutrophils, and ulinastatin (3100 U/ml) a twofold increase in neutrophils stimulated with fMLP or IL-8. When the protease inhibitors were added to the cell suspension after the phagocytosis of lumispheres, CL responses rapidly increased again to the level which was observed when both protease inhibitors and neutrophil stimulants were incubated simultaneously. In contrast, extracellular release of oxygen metabolites from stimulated neutrophils, assayed by a conventional measurement of luminol-dependent CL, was reduced by the protease inhibitors in a dose dependent fashion. When luminol-unbound microspheres were incubated with neutrophils stimulated by fMLP in luminol solution, extracellular CL was almost completely inhibited by gabexate mesylate. These results indicate that the protease inhibitors enhance the generation of intracellular CL and suppress the extracellular release of free radicals.

Dose-Response Relationship, Drug↗
PubMed1992

An insulin-like growth factor II-producing histiocytoma associated with hypoglycemia: analysis of the peptide, its gene expression, and glucose transporter isoforms.

An insulin-like growth factor II (IGF-II)-producing histiocytoma was detected in a patient presenting with the classical findings of tumor-related hypoglycemia (low serum insulin and IGF-I concentrations, glucose intolerance, and only modestly increased serum IGF-II levels). Acid-gel filtration of serum extracts showed a single peak of IGF-II immunoreactivity that emerged at the same site as the 125I-labeled human IGF-II standard. High-performance liquid chromatography (HPLC) analysis of the tumor IGF-II demonstrated that it had an identical retention time to that of recombinant human IGF-II. The tumor IGF-II content was extremely high, messenger RNA (mRNA) for IGF-II showed a 100-fold increase in expression compared with normal human liver tissue. Of special interest, a newly identified exon (hE1) was shown to be predominantly expressed in the tumor by Northern blot analysis using leader exon-specific rat IGF-II complementary DNA (cDNA) probes. Although the significance of this finding remains uncertain, this is the first evidence of a new transcription unit in the human IGF-II gene. In addition, immunoblotting showed that the levels of the glucose transporters, GLUT1 and GLUT4, in the tumor were low and undetectable, respectively. This finding makes it unlikely that increased glucose consumption by the tumor accounted for the hypoglycemia in this patient. This case report provides an interesting insight into the pathophysiology of tumor-induced hypoglycemia and new evidence of the abnormal regulation of IGF-II gene expression in human tumors.

Animals↗
PubMed1992

Continuing V gamma 2 to J gamma 2 rearrangements of murine T cell receptor gamma genes in a B-committed immature cell line.

In SPL2-1-2, a murine B-committed immature cell line transformed with a temperature-sensitive mutant of Abelson virus, T cell receptor (TCR) gamma gene rearrangements, together with IgH gene rearrangements, were induced during culture at a non-permissive temperature (39 degrees C). During 11-12 months of culture, TCR gamma gene rearrangements occurred in all cells. In contrast to TCR gamma genes, neither TCR beta or TCR delta were detected even after 11-12 months of culture at a non-permissive temperature. The majority of the TCR gamma gene rearrangements observed here were V gamma 2 to J gamma 2 joinings and the remaining rearrangements were J gamma 1-linked. V gamma 1 to J gamma 4 and V gamma 3 to J gamma 3 joinings were not detected. Approximately 70% of cells with TCR gamma gene rearrangements produced normal-sized transcripts from the rearranged TCR gamma genes. Cloning and sequencing analysis of a cDNA from the transcripts demonstrated that the whole structure of the cDNA was similar to that of T-lineage cells. These results showed that TCR gene rearrangements were restricted to the gamma genes and that V gamma 2 to J gamma 2 joinings occurred preferentially in this B-committed immature cell line. Furthermore, TCR gamma gene rearrangements also occurred in intracytoplasmic mu-chain producing cells. This indicated that the existence of intracytoplasmic mu-chains did not prevent TCR gamma gene rearrangements, although the existence of mu-chains is known to inhibit further productive IgH gene rearrangements, (allelic exclusion). These results should provide many implications for the mechanism of TCR gene rearrangements, especially that of cross-lineage rearrangements.

Animals↗
PubMed1992

Circulating interleukin 6 as a useful marker for predicting postoperative complications.

We examined postoperative serial changes in the levels of serum interleukin 6 (IL-6), serum acute phase reactants (APRs) and plasma neutrophil elastase (NE) in patients with various cancers and reviewed these changes in patients who did, and did not, show postoperative complications. Serum IL-6 level was elevated after surgery, peaking on the first postoperative day. Elevation of serum APRs and plasma NE levels also followed. There was a significant correlation between the serum peak level of IL-6 and those of APRs and NE (P less than 0.01). Moreover, there was a significant difference in the serum IL-6 level in patients with and without complications. The relationship between the serum IL-6 greater than 400 pg/ml and the incidence of postoperative complications was also marked. These results suggest that circulating IL-6 is a clinically useful marker for the earliest detection and prediction of postoperative complications.

Adult↗
PubMed1992

Expression of glucose transporter isoforms with aging.

To elucidate the cellular mechanisms for impairment of glucose metabolism associated with aging, the facilitative glucose transporter protein and mRNA were studied in various tissues of young (7-week-old) and aged (20-month-old) rats. GLUT4 glucose transporter protein, a major glucose transporter isoform in the insulin-responsive tissues, was selectively decreased in the epididymal fat tissues of the aged rats compared with the young rats. This decrease is likely to be due to a decrease in protein synthesis rather than in protein stability, since GLUT4 mRNA per unit cellular total RNA was also decreased. GLUT4 mRNA in the skeletal muscle was rather increased in spite of the decreased level of GLUT4 protein in the aged rats, suggesting that the translational efficiency and/or stability of GLUT4 protein is decreased in the skeletal muscle of the aged rats compared with the young rats. In contrast to these alterations in GLUT4 expression, no apparent decrease in the GLUT1 protein amount was observed in the fat tissues, skeletal muscle and brain of the aged rats compared with the young rats. Thus, the tissue and isoform-specific alterations in glucose transporter expression are associated with aging and may contribute to impairment of glucose metabolism observed with aging.

Adipose Tissue↗
PubMed1992

Efficacy of percutaneous transluminal coronary angioplasty in patients with acute myocardial infarction complicated by cardiogenic shock.

Cardiogenic shock still remains a highly lethal complication of acute myocardial infarction (AMI). This study reviews our hospital experience in treating AMI complicated by cardiogenic shock to evaluate whether coronary angioplasty improves survival or not. We have treated 523 AMI patients from 1985 to 1990, and among these, 26 patients with AMI complicated by cardiogenic shock who underwent percutaneous transluminal coronary angioplasty (PTCA) compose the study group. In 16 patients, PTCA was successful (Groups S) and in 10 patients, unsuccessful (Group F). There were no statistical differences between the Groups with respect to clinical background, intraaortic balloon counterpulsation (IABP) or emergency coronary bypass graft surgery. Before PTCA, hemodynamic variables including cardiac index, pulmonary capillary wedge pressure and systolic blood pressure were similar in the 2 groups. After PTCA, cardiac index in Group S patients was better than in Group F patients (2.18 +/- 0.61 versus 1.62 +/- 0.65, p less than 0.05). Thirty day and 1 year survivals were also better in Group S than in Group F (30 day survival: Group S 56.2%, Group F 10%, 1 year survival: Group S 31.2%, Group F 0%, p less than 0.05). Multivariate analysis showed that age under 75 years old, systolic blood pressure over 90 mmHg after PTCA and successful PTCA were independent predictors of 30 day survival (p less than 0.05). It was suggested that PTCA was an effective procedure to reduce mortality in patients with cardiogenic shock.

Adult↗
PubMed1992

Upregulation of GLUT2 mRNA by glucose, mannose, and fructose in isolated rat hepatocytes.

Previously, demonstrated that GLUT2 mRNA and protein are increased in liver of streptozocin-induced diabetic rats. To examine the mechanisms whereby GLUT2 mRNA is regulated, we cultured isolated hepatocytes in the absence and presence of various concentrations of glucose. Culture of hepatocytes in high glucose concentration (27.8 mM) for 20 h induced a 3.2-fold increase in GLUT2 mRNA levels compared with hepatocytes cultured without D-glucose. Interestingly, D-mannose and D-fructose could substitute for D-glucose to elevate the GLUT2 mRNA level, whereas 3-O-methyl-D-glucose, 2-deoxy-D-glucose, and sucrose, which were not metabolized or taken up by the cells, were without effect. Insulin had no significant effect on GLUT2 mRNA levels in hepatocytes in the presence or absence of D-glucose. Therefore, the regulation of the GLUT2 gene by D-glucose in hepatocytes is contrary to that reported for GLUT1 and GLUT4 genes, which are downregulated by D-glucose. These results also suggest that the elevated GLUT2 mRNA level observed in diabetic rat liver is due to the high blood glucose concentration rather than to insulin deficiency.

3-O-Methylglucose↗
PubMed1992

Transitory expression of Thy-1 antigen in immature B cell lines.

In cmu- B220+ Thy-1- murine immature B cells transformed with a temperature-sensitive mutant of Abelson murine leukemia virus, a low level of Thy-1 antigen was transitorily expressed after the shift of the culture temperature from the permissive (35 degrees C) to the non-permissive (39 degrees C) temperature. On the other hand, B220 antigen was persistently expressed regardless of whether the cells were cultured at the permissive or non-permissive temperature. No other T-lineage-specific antigens, CD3, CD4, and CD8 were induced during the culture at the non-permissive temperature. Expression of Thy-1 antigen was confirmed by the detection of a low level of Thy-1-specific mRNA. These results clearly showed that immature B cells could express Thy-1 antigen during proliferation and/or differentiation. The results imply a role for Thy-1 antigen in B cell proliferation and/or differentiation.

Animals↗
PubMed1992

Regulation of Thy-1 gene expression by the methylation of the 5' region of Thy-1 gene and intracellular regulatory factors in immature B cells.

In c mu- B220+ Thy-1- FL2-52-2, an immature B cell line transformed with a temperature-sensitive mutant of Abelson murine leukemia virus(ts OS-59), Thy-1 antigen expression was induced after the shift of the culture temperature from a permissive(35 degrees C) to a non-permissive temperature(39 degrees C), and a Thy-1+ subclone, FL2-52-2-1 was isolated by limiting dilution. Furthermore, since a population of Thy-1+FL2-52-2-1 lost Thy-1 antigen expression during culture at a non-permissive temperature, Thy-1- FL2-52-2-1-1 was isolated from the cultured cells. Methylation analysis by Southern blotting experiments showed that 5' region of the Thy-1 gene was methylated in Thy-1- FL2-52-2 but demethylated in Thy-1+ FL2-52-2-1 and Thy-1-FL2-52-2-1-1. To determine whether or not there exist intracellular regulatory factors responsible for Thy-1 gene expression, Thy-1a allele was transfected into Thy-1(Thy-1.2-) FL2-52-2 and Thy-1- FL2-52-2-1-1. The transfected Thy-1a allele was expressed in Thy-1- FL2-52-2, but not in Thy-1- FL2-52-2-1-1, indicating the presence of the intracellular regulatory factors requisite for Thy-1 gene expression in Thy-1- FL2-52-2. It appeared that in Thy-1- FL2-52-2-1-1, Thy-1 gene was not expressed because of the absence of the intracellular regulatory factors although the 5' region of the Thy-1 gene was demethylated. These results indicated the existence of at least two regulatory mechanisms of Thy-1 gene expression in immature B cells: methylation of the 5' region of the Thy-1 gene and intracellular regulatory factors.

Animals↗
PubMed1992

[A case of citrullinemia associated with isolated ACTH deficiency, rapidly developing coma].

We report a 41-year-old male of citrullinemia associated with argininosuccinate acid synthetase deficiency. He was admitted to the Hitachi General Hospital because of finger tremor, restlessness and urinary incontinence. He had short stature and a poor appetite. Laboratory evaluation was summarized as follows: mild hypoglycemia, low plasma cortisol levels, delayed response of 17-OHCS and 17-KS to ACTH administration in urine, and delayed response of plasma ACTH level to insulin administration. In this case, ACTH deficiency is estimated to be a dysfunction of the hypothalamus. Replacement therapy of hydrocortisone improved his symptoms. He was readmitted to the hospital because of delirium and confusion, two weeks after the hydrocortisone administration. At that time, he had flapping tremor. Laboratory examination revealed hyperammonemia (NH3: 231 micrograms/dl) and mild elevation of GOT and GPT. Serum and urinary amino acid determination showed marked elevation of citrulline (478.1 nmol/ml in serum, 4681.2 mumol/day in urine). Lactulose administration, low protein diet and plasmapheresis were started, but he went into a coma. Without any improvement, he died on the 29th hospital day. Autopsy examination of the liver disclosed fatty change. Adrenal cortex depicted severe atrophy. Biochemical analysis of urea cycle enzymes of the liver and kidney showed decreased activity of argininosuccinate synthetase (liver: 0.0022 U/mg protein, 5% of that normal liver, kidney: 0.003 IU/mg protein, 20% of that in normal kidney). Citrullinemia associated with ACTH deficiency have not reported in the literature. It may be presumed that ACTH deficiency is concerned with the delayed onset of hyperammonemia. The relation between citrullinemia and endocrinological abnormalities is also discussed.

Adrenal Cortex↗
PubMed1992

[Establishment of EGF, EGF-R and FN-R positive human adenocarcinoma cell line (GAC-1)].

A human adenocarcinoma cell line designated as GAC-1, was established from ascites of the 56-year old male patient with rapidly progressive gastric cancer. The doubling time was about 18.5 hours in vitro, and cell cycle analysis using flow cytometry showed marked increase of S phase (46.1%). Immunohistochemical demonstration of GAC-1 cells revealed positive staining of TGF-alpha, EGF, EGF-R, FN-R, laminin and negative staining of fibronectin. Histogram of them indicated aneuploidy with modal number 57 and they formed tumors in nude mice.

Adenocarcinoma↗
PubMed1992

Early detection of coronary artery graft dysfunction with intraoperative 2-dimensional transesophageal echocardiography.

We report 5 cases in which intraoperative transesophageal echocardiography was instrumental in the early detection of a left ventricular wall-motion abnormality caused by acute dysfunction of a coronary artery bypass graft. The appearance of a wall-motion abnormality on transesophageal echocardiography preceded signs of myocardial ischemia when such signs were detectable with routine monitoring. By facilitating prompt, appropriate correction of technical problems, transesophageal echocardiography enabled the blood flow to be restored and the ischemic insult to be resolved without further complication.

Journal Article↗
PubMed1991

Immunocytochemical demonstration of salmon GnRH and chicken GnRH-II in the brain of masu salmon, Oncorhynchus masou.

We have recently developed sensitive and specific radioimmunoassays (RIAs) for salmon gonadotropin-releasing hormone (sGnRH) and chicken GnRH-II (cGnRH-II) and have measured the contents of both GnRHs in the rainbow trout brain. Our results showed that contents of the two GnRHs are variable among different brain regions. Therefore, in order to confirm the differential distribution of the two GnRHs by a different technique, we examined the distribution of immunoreactive sGnRH and cGnRH-II in the brain of masu salmon by using immunocytochemical techniques. sGnRH immunoreactive (ir) cell bodies were scattered in the transitional areas between the olfactory nerve and the olfactory bulb, the ventral olfactory bulb, between the olfactory bulb and the telencephalon, the ventral telencephalon, and the preoptic area. These sGnRH-ir cell bodies were dispersed in a strip-like region running rostrocaudally in the most ventral part of the ventral telencephalon. sGnRH-ir fibers were distributed in the various brain regions from the olfactory bulb to the spinal cord. They were especially abundant in the olfactory bulb, ventral telencephalon, preoptic area, hypothalamus, deep layers of the optic tectum, and thalamus. sGnRH-ir fibers also innervated the pituitary directly. cGnRH-II-ir cell bodies were found in the nucleus of the medial longitudinal fasciculus (nMLF). The distribution of cGnRH-II-ir fibers was similar to that of sGnRH-ir fibers, except that cGnRH-II-ir fibers were absent in the pituitary. The number of cGnRH-II-ir fibers was much fewer than that of sGnRH-ir fibers. The results of the present immunocytochemical study are in basic agreement with those of our previous RIA study. Thus, we suggest that in masu salmon, sGnRH not only regulates gonadotropin (GTH) release from the pituitary but also functions as a neuromodulator in the brain, whereas cGnRH-II functions only as a neuromodulator.

Aging↗
PubMed1991

The glossopharyngeal nerve of the axolotl labeled with carbocyanine dye (diI).

Fluorescent carbocyanine dye (diI) was used to label the glossopharyngeal (IX) nerve in the fixed preparation of the Mexican salamander, axolotl. When the cell bodies were viewed with a confocal laser scanning microscope and Nomarski optics, the cytoplasm was brightly fluorescent, but not the cell nucleus. The cell bodies which send peripheral axons in the two branches of the IX nerve were mainly distributed in the rostral part of the combined glossopharyngeal-vagus ganglion, but a few cells were also distributed in the middle and caudal parts. This may indicate a relatively undifferentiated organization of the IX nerve in the ganglion.

Ambystoma↗
PubMed1991

Expression of the GLUT1 glucose transporter increases thymidine uptake in Chinese hamster ovary cells at low glucose concentrations.

An increase in expression of the GLUT1 glucose transporter gene has been observed to be associated with an increase in glucose transport activity upon oncogenic transformation of the cells. Increased expression of this glucose transporter isoform has been also observed in fetal tissues. To investigate the consequences of this phenomenon on cellular metabolism and cell growth, an expression vector containing the GLUT1 glucose transporter complementary DNA was transfected into Chinese hamster ovary cells. Overexpression of this glucose transporter isoform resulted in an increase in not only glucose uptake and utilization but also thymidine uptake when cells were exposed to glucose-deficient conditions. This increase in glucose metabolism and DNA synthesis may play an important role on the growth and/or survival of cancer cells and fetal tissues.

3-O-Methylglucose↗
PubMed1991

The glucose transport activity of GLUT1 is markedly decreased by substitution of a single amino acid with a different charge at residue 415.

GLUT1 glucose transporter cDNA was modified to introduce a single amino acid substitution of aspartic acid for asparagine 415, which is conserved among all facilitative glucose transporter isoforms. Although a significant amount of the mutated transporter was expressed into plasma membranes of Chinese hamster ovary cells by transfection with expression vector, almost no increase in glucose transport activity was observed. Analysis of glucose uptake with Lineweaver-Burk plot depicts that the mutation induced a marked decrease (more than 5-fold) in turnover number and a slight increase (1.5-fold) in Km compared with the wild-type GLUT1. Results obtained with cytochalasin B and ethylidene glucose suggested that the inner but not outer glucose binding site was modulated. These results suggest that asparagine 415 is located close to the inner glucose binding site and the putative inner gate of GLUT1 glucose transporter and that an ionic charge in this domain might play an important role in the rate of conformational change between an inward-facing form and an outward-facing form of glucose transporter.

Animals↗