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T Asano

Publications and source records attributed to T Asano.

At least 523 records · Page 29Linked to original sources
PubMed1992

Deletion of C-terminal 12 amino acids of GLUT1 protein does not abolish the transport activity.

We engineered the GLUT1 cDNA to delete C-terminal 12 amino acids of encoded GLUT1 protein. This mutated GLUT1 protein expressed in CHO cells by transfection of its cDNA was demonstrated to reside on the plasma membrane by cell surface labeling technique, and retain the transport activity, similar to that of the wild-type GLUT1. In addition, metabolic labeling of the intact cells with 35S indicated that the half-life of the mutated GLUT1 was not significantly different from that of the wild-type GLUT1. These results suggest that C-terminal 12 amino acids of GLUT1 are not important for the transport activity and the stability of the protein. Taken together with our previous results on the mutant without C-terminal 37 amino acids, the amino acids between the 37th and the 13th from the C-terminus appear to be essential for the transport activity.

Animals↗
PubMed1992

Studies of alcohol-induced interdigitated gel phase in phosphatidylcholine multilamellar vesicles by the excimer method.

We have developed a new spectroscopic method (excimer method) for detecting the interdigitated gel phase (L beta I) in phospholipid vesicles. This method is based on the disappearance of an excimer fluorescence peak of pyrenephosphatidylcholine (pyrene-PC) in the L beta I phase. Using this method we have studied the phase transition from gel phase (L beta') to L beta I phase of dipalmitoylphosphatidylcholine multilamellar vesicles in the presence of ethanol or ethylene glycol (EG). In both the cases of ethanol and EG, a sharp decrease in the ratio of excimer to monomer fluorescence intensity (E/M) of pyrene PC appeared at the same concentration of the transition from L beta' to L beta I as determined by the X-ray diffraction method or the scanning density method. After the transition to the L beta I phase, E/M values became very low. This excimer method enables us to detect the L beta I phase in unilamellar vesicles of phospholipids, which can hardly be studied by other methods such as X-ray diffraction.

Ethanol↗
PubMed1992

Copurification of small heat shock protein with alpha B crystallin from human skeletal muscle.

Immunoreactive alpha B crystallin and a 28-kDa protein in an extract of human pectoral muscle were precipitated by (NH4)2SO4 at 40% saturation, and coeluted during column chromatography on DEAE-Sepharose and on Bio-Gel A-5m. The two proteins were separated on a column of S-Sepharose HP in the presence of 7 M urea. Further chromatography of each of the two resultant fractions on a column of Superdex 75 pg and on a TSK-SP 5PW column in the presence of urea yielded preparations of alpha B crystallin and the 28-kDa protein each of which gave a single band on sodium dodecyl sulfate-polyacrylamide gel electrophoresis. The final preparation of 28-kDa protein contained at least two subtypes, which were separable on the TSK-SP column. However, fragmentation patterns of the two major 28-kDa proteins after digestion with endoproteinase Asp-N were identical. Amino acid sequences of peptides formed by cleavage of the purified 28-kDa protein and alpha B crystallin were identical to those of particular regions of the deduced amino acid sequences of human small heat shock protein (HSP28) and lens alpha B crystallin, respectively. Using an immunoassay method, with antibodies raised in rabbits, we found that HSP28 was present in all human tissues tested and at high levels (greater than 1 micrograms/mg protein) in the heart and other tissues composed of striated and smooth muscles. HSP28, found with alpha B crystallin, in extracts of several human and bovine tissues was trapped on and coeluted with alpha B crystallin from an affinity column prepared with antibodies against alpha B crystallin. This result suggests that the two proteins are associated in cells.

Amino Acid Sequence↗
PubMed1992

Glucose binding enhances the papain susceptibility of the intracellular loop of the GLUT1 glucose transporter.

Digestion of human GLUT1 protein in erythrocytes with 5 micrograms/ml papain for 5 min yielded several fragments. By using several site-specific antibodies, two of these fragments containing the intracellular loop domain between M6 and M7 were demonstrated to be further digested by a prolonged incubation with papain. The addition of 0.2 M D-glucose enhanced this digestion between M6 and M7 by approximately 3.5-fold, while the addition of 0.2 M D-sorbitol exhibited no effects. These results strongly suggest that D-glucose binding induces the conformational change of the intracellular loop domain between M6 and M7 of GLUT1 protein. Since the homology of the amino acid sequence was low in this intracellular domain among the five facilitative glucose transporter isoforms, this intracellular loop might contribute to the difference in their Km and Vmax values for glucose uptake.

Erythrocyte Membrane↗
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

Surgical laser ablation of a pediatric idiopathic ventricular tachycardia.

A pediatric patient with medically refractory idiopathic ventricular tachycardia was successfully treated by surgical laser ablation. Application of laser on the normothermic beating heart enables continuous electrophysiological assessment. The histopathology of idiopathic ventricular tachycardia and the advantages of laser ablation are presented.

Atrioventricular Node↗
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

Characterization of two differently glycosylated molecular species of yeast-derived hepatitis B vaccine carrying the pre-S2 region.

Modified hepatitis B virus surface antigen M protein particles (HBsAg M-P31c) produced in yeast is mainly composed of two differently glycosylated proteins, GP37 and GP34. GP37 has an N-linked sugar chain and O-linked sugar chains; and GP34 has an N-linked sugar chain bound to the peptide backbone P31. Although M-P31c vaccine elicits both anti-S and anti-pre-S2 antibodies, whether there are any differences between GP37 and GP34 in the ability to elicit these antibodies is still unknown. To clarify this issue, we prepared particles which were composed solely of GP37 or GP34 by affinity chromatography, using polymerized human serum albumin as a ligand and digestion with alpha-mannosidase. We also prepared particles composed solely of P31 by successive digestion with alpha-manosidase and endo-beta-N-acetylglycosaminidase H. The vaccines derived from these three kinds of particles elicited both anti-S and anti-pre-S2 antibodies in mice to the same extent as the original M-P31c vaccine. These results suggest that the N- and O-linked sugar chains of M-P31c component proteins produced in the host yeast cells have no effect on the ability to elicit anti-S and anti-pre-S2 antibodies and that there are no differences with respect to antibody response in mice between the two major components of M-P31c, GP37 and GP34.

Animals↗
PubMed1992

Effects of isopropanol on the development of inflammatory reactions in rats.

The effects of isopropanol on the development of inflammation were studied in rats. Isopropanol inhibited both the histamine-induced increase in cutaneous vascular permeability and the carrageenan-induced plasma exudation into the pleural cavity. The lipopolysaccharide-induced leucocyte emigration into the subcutaneous pouch was unaffected by isopropanol, but the leucocyte emigration of carrageenan-induced pleural inflammation was markedly inhibited by isopropanol. In contrast, when isopropanol was administered with an anti-inflammatory drug (indomethacin or dexamethasone), it enhanced the pleural inflammatory reaction. These results suggest that isopropanol may exert toxic effects through interference with the normal processes of inflammation and interaction with other agents that affect inflammatory reactions.

1-Propanol↗
PubMed1992

Phase transitions of phospholipid vesicles under osmotic stress and in the presence of ethylene glycol.

The effects of poly(ethylene glycol) (PEG) on the phase transition of phospholipid multilamellar vesicles (MLVs) were investigated by using differential scanning calorimetry (DSC). Main transition temperature (Tm) and the pre-transition temperature (Tp) of neutral phospholipid-, DMPC-1, DPPC- and DSPC-MLVs increased with an increase in PEG concentration. The subtransition temperature of DPPC-MLV also increased with an increase in PEG concentration. These results could be qualitatively explained by enhancement of the lateral packing on the basis of the osmoelastic coupling theory. The pretransition temperature increased faster than the main transition temperature did with an increase in PEG concentration. The increment of Tm depended on the hydrocarbon chain length, the shorter the hydrocarbon chain length was, the larger the increment was. The transition width in the DSC peak was broadened with an increase in PEG concentration. These three above-mentioned effects are the main differences between the effects of the osmotic stress on the phase transition of MLVs and those of hydrostatic pressure. On the other hand, ethylene glycol (EG), which is the monomer of PEG, had a biphasic effect on transition temperature of DPPC-, DSPC-, and DMPC-MLV, reducing Tm and Tp at low concentrations, but increasing Tm and extinguishing pretransition at high concentrations. This is explained by the induction of an interdigitated gel phase at high concentrations of EG, which indicates that EG can easily penetrate into the head group region of the lipid, in contrast with PEG 6K, because EG is small. Temperature-EG concentration phase diagrams for the various PC-MLVs were determined.(ABSTRACT TRUNCATED AT 250 WORDS)

Calorimetry, Differential Scanning↗
PubMed1992

Environmental dose assessment for low-level radioactive effluents discharged from Tokai reprocessing plant.

In the normal operation of the Tokai reprocessing plant, low-level radioactive effluents are discharged to the atmosphere and the ocean under rigid control. Radiation exposures to the population around the plant have been estimated for potential pathways with site-specific parameters such as food consumption, concentration factors of marine organisms, and meteorological conditions. External exposures to a radioactive cloud and internal exposures from inhalation and oral intake of radionuclides are evaluated for airborne effluents. External exposures to a contaminated fishing net and fishing boat are considered pathways for fishermen. External exposure to a contaminated beach and internal exposure via oral intake of marine products are evaluated for liquid effluents. Since the plant began operation in 1977, estimated effective dose equivalents for the public have been less than the annual effective dose equivalent limit of 0.1% recommended by the International Commission on Radiological Protection (1977).

Air Pollution, Radioactive↗
PubMed1992

Prediction of viability of ischemically damaged canine pancreatic grafts by tissue flow rate with machine perfusion.

We studied the viability of canine pancreatic grafts using a short-time perfusion technique with an organ perfusion machine, "ORPH3000C". The following parameters were examined during perfusion of warm ischemically damaged grafts: Amylase, lipase, and insulin levels in the perfusate after 1-hr perfusion showed no significant correlation with warm ischemic time (WIT), and these indices could not be used to assess graft viability. Tissue flow rate (TFR) at the end of perfusion was significantly decreased with prolonged WIT. TFR correlated with the percent decrease in tissue SOD activity, thus TFR was a reliable predictor of reperfusion injury. Histological studies showed no findings attributable to warm ischemic injury before 1-hr perfusion. After 1-hr perfusion, the grafts were allotransplanted and the relation between TFR and endocrine function of the transplanted grafts was examined. TFR correlated with K value calculated from IV-GTT performed on day 5 postoperatively, suggesting that TFR is a predictable index of isolated pancreatic graft viability. Using TFR levels, this method allowed us to select only grafts with good function prior to transplantation. This technique appears to be of use for pancreatic transplantation from cadaver donors after cardiac arrest.

Animals↗
PubMed1992

Two forms of G(o) type G proteins: identification and distribution in various rat tissues and cloned cells.

A G(o) type G protein distinct from the major species of G(o) was recently isolated from bovine brain and designated G(o)*. The cDNAs encoding two forms of mammalian G(o) alpha were also isolated and designated GoA alpha and GoB alpha. To recognize two forms of G(o) type G proteins, we raised antibodies in rabbits against two peptides with sequences found only in the respective proteins of murine GoA alpha (SNTYEDAAAYIQTQF) and GoB alpha (TEAVAHIQGQYWSK). Purified anti-GoA alpha antibodies reacted with the major species of G(o) alpha purified from bovine and rat brain, whereas anti-GoB alpha antibodies reacted only with rat G(o)*alpha, but not with the major species of G(o) alpha or bovine G(o)*alpha. These results indicate that the major species of G(o) alpha is encoded by GoA alpha cDNA and G(o)*alpha is encoded by GoB alpha cDNA. Using these antibodies, the distribution of GoA and GoB was studied in various rat tissues and cloned cells. Both GoA and GoB were present in many tissues, but their distribution in peripheral tissues was distinct. GoA alpha seemed to associate mainly with neural tissues. On the other hand, relatively high concentrations of GoB alpha were present in the brain, pituitary gland, adipose tissue, lung, and testis. The concentrations of both GoA and GoB in the brain increased during ontogenic development, but the increase in GoB was observed at a later age. Both GoA and GoB were found in such cloned cells as PC12, NG108-15, C6, GA-1, G8, and 3T3-L1 cells. Treatment of PC12 cells with nerve growth factor caused the extension of neuron-like processes and the increase in the level of GoA, but not in the level of GoB.

3T3 Cells↗
PubMed1992

Differential localization of G proteins, Gi and Go, in the olfactory epithelium and the main olfactory bulb of the rat.

The immunohistochemical localization of proteins Gi1 (plus Gi3). Gi2 and Go was studied in the olfactory epithelium and the main olfactory bulb of rats, using purified antibodies to the respective alpha subunits and beta gamma subunits of these G proteins. In the olfactory epithelium, only a restricted population of olfactory cells was immunopositive for Gi2 alpha, but others were not. The immunoreactivity for Gi1 alpha/Gi3 alpha was not observed. The olfactory epithelium was immunopositive for both Go alpha and beta gamma, but its apical surface was immunopositive only for beta gamma. In the main olfactory bulb, all layers were intensely immunopositive for Go alpha and beta gamma but weakly for Gi2 alpha. In contrast to the negative or weak immunostainings in the olfactory nerve fiber layer and glomeruli, the molecular and the internal granular layers were intensely immunopositive for Gi1 alpha/Gi3 alpha. These findings suggest the functional difference among Gi1/Gi3, Gi2 and Go in the signal transduction in the olfactory system.

Animals↗
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

Production and specificity of anti-22-oxacalcitriol antisera.

22-Oxacalcitriol 3-hemiglutarate, a haptenic derivative of 22-oxacalcitriol, was synthesized to obtain a specific antibody for use in radioimmunoassay. Three antisera were elicited in rabbits against the hapten conjugated with bovine serum albumin, and their specificity was examined by cross-reaction study. One of the antisera was found to be satisfactorily specific, and expected to provide a radioimmunoassay useful for the pharmacokinetic study of 22-oxacalcitriol.

Animals↗
PubMed1992

5-Isoquinolinesulfonamide derivatives. III. Synthesis and vasodilatory activity of 1-(5-isoquinoline-sulfonyl)piperazine derivatives.

On the basis of a hypothesis that cyclization and alkylation of the diamine part in formula 1 may give highly active compounds, a new series of 5-isoquinolinesulfonamide derivatives, shown as formula 2, were prepared from cyclic diamines. Their vasodilatory effects were subsequently evaluated in vivo according to the increase in arterial blood flow after the formulas were injected locally to the femoral and/or vertebral arteries of dogs. Cyclization of the diamine structure in formula 1 gave very potent vasodilators: 6 and 14. Acylation and sulfonylation of terminal amino nitrogen afforded much less potent compounds. In contrast to the hypothesis, alkylation on the ring carbon and the terminal nitrogen of the cyclic amine afforded less active compounds except for compound 11. The most active compounds, 6, 11 and 14, showed more potent vasodilatory effects and more selective activity to the vertebral artery than either trapidil or diltiazem.

Animals↗