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Biomedical subjects

Y Yazaki

Publications and source records attributed to Y Yazaki.

At least 649 records · Page 36Linked to original sources
PubMed1993

Expression of intercellular adhesion molecule-1 in rat heart with ischemia/reperfusion and limitation of infarct size by treatment with antibodies against cell adhesion molecules.

To elucidate the mechanism(s) of myocardial reperfusion injury, we investigated the roles of cell adhesion molecules on both leukocytes and vascular endothelial cells in the reperfused myocardia. We found that within 2 hours after reperfusion leukocytes began to infiltrate into the rat myocardia subjected to 30 minutes of ischemia and clarified, for the first time, that the expression of intercellular adhesion molecule-1 was enhanced on the capillary and venous endothelial cells from 8 to 96 hours after the start of reperfusion. Furthermore, pretreatment with individual monoclonal antibodies against cell adhesion molecules (CD11a, CD11bc, CD18, and intercellular adhesion molecule-1) reduced not only the infiltration of leukocytes but also the area of infarction in the reperfused hearts. These observations suggest that cell adhesion molecules play a critical role in the pathogenesis of myocardial reperfusion injury.

Animals↗
PubMed1993

Laparoscopic cholecystectomy: the Japanese experience.

We investigated the current status of laparoscopic cholecystectomy in Japan. A retrospective survey of laparoscopic cholecystectomy was performed involving 1989 patients from eight Japanese institutions. The preoperative work-up and the operative technique were largely identical to those in the United States. Conversion to open cholecystectomy was required in 54 patients (2.7%) because of unexpected intraoperative findings such as inflammation and adhesions in 40 patients (2.0%) and intraoperative complications in 14 patients (0.7%). There were no deaths, and postoperative complications occurred in 34 of 1935 patients (1.75%) in whom laparoscopic cholecystectomy was completed. Only 10 patients (0.51%) had serious complications (hemorrhage and bile duct injury, for example) that required laparotomy. The incidence of bile duct injury was 11 of 1989 (0.55%). We conclude that the adoption of laparoscopic cholecystectomy in Japan has been highly successful.

Cholecystectomy, Laparoscopic↗
PubMed1993

Mutational analysis of human lipoprotein lipase by carboxy-terminal truncation.

We have previously reported a Trp382 (TGG)-->stop (TGA) mutation that causes familial lipoprotein lipase (LPL) deficiency. Expression study of the Trp382-->stop mutant showed that the truncated LPL was catalytically inactive with a marked reduction in the expressed mass. To investigate the minimal amino-terminal sequence of human LPL required for an active enzyme, a series of carboxy-terminal (C-terminal) truncated LPLs were expressed in vitro, and the enzyme activity, mass, and LPL mRNA levels were analyzed. The lipolytic activity showed a stepwise reduction between LPL-437 (Cys438-->stop; 68% of normal LPL activity in medium) and LPL-434 (Phe435-->stop; 3%). Without affecting LPL mRNA levels, LPL mass was reduced with the mutants not larger than LPL-437. In terms of specific activity, a significant difference was observed between LPL-436 (Lys437-->stop; 88% of that of normal LPL in medium) and LPL-435 (Val436-->stop; 22%), implying the importance of the role of Val436 in LPL action. Furthermore, our results unexpectedly showed that LPL-446 (Ser447-->stop), which is considered to be a common polymorphic form of LPL, exhibited higher activity than normal LPL (185% in medium). These results demonstrate that the C-terminal region of human LPL is closely associated with the expression of enzyme mass and catalytic activity.

Amino Acid Sequence↗
PubMed1993

[Regulation of the myosin heavy chain gene expression during cardiac hypertrophy induced by pressure-overload].

In response to pressure-overload, the myocardium exhibits a complex molecular changes, characterized by the reexpression of a fetal phenotypes. Although signaling pathways involved in these changes are still largely unknown, studies on the differential expression of the myosin heavy chain (MHC) genes will provided a framework for understanding the molecular mechanisms underlying the reprogramming of cardiac gene expression in response to mechanical load. Recently, in vitro medel of myocardial stretch on the silicone sheet has demonstrated the up regulation of the "cardiac fetal genes", including beta-MHC, skeletal alpha-actin, and atrial natriuretic factor (ANF), which is known to be a hallmark of the altered gene expression in the hypertrophic heart. Transient transfection experiments using this model will be useful for identifying the "stretch-response element" within the promoters of these genes. Furthermore, this approach will eventually identify the stretch-induced intracellular pathways.

Animals↗
PubMed1993

[Assessment and evaluation of cardiac function].

Assessment and evaluation of cardiac function have become commonplace in the care of cardiac patients with acute or chronic disorders, since therapy of most cardiac diseases is designed specifically to improve ventricular function. Now, various techniques are available for quantitative measurements of the size, shape and motion of the ventricle. Ventricular dysfunction is defined with two components, systolic and diastolic dysfunction, and can be described hemodynamically in terms of the ventricular pressure-volume diagram. Pure systolic dysfunction is associated with a depression in the end-systolic pressure-volume relation, using the Frank-Starling relation to restore cardiac output toward normal. In contrast, pure diastolic dysfunction is associated with preservation of the end-systolic pressure-volume relation but distortion of the diastolic relation, showing higher diastolic pressure at any given volume. However, in patients presenting clinically with heart failure, both systolic and diastolic dysfunction are usually observed. In this context, factors and disorders that influence ventricular dysfunction are described, considering extrinsic or intrinsic to the ventricular chambers.

Cardiac Output↗
PubMed1993

[Molecular basis for cardiac functions].

Cardiac functions are regulated by both contractile proteins and calcium regulatory proteins. Alterations of these are considered involved in impaired contractile and diastolic functions in hypertrophied hearts. In this study, we analyzed molecular changes during the development of cardiac hypertrophy. Cardiac hypertrophy was induced by constricting the pulmonary artery in rabbits or the aorta in rats. In rabbit right ventricular hypertrophy, protein synthesis was increased to 1.8 times the control 2-4 days after pulmonary constriction. This increase in protein synthesis could be classified as an increase in both capacity and efficiency of synthesis. beta-cardiac myosin heavy chain (beta-MHC) isoform was predominantly expressed and alpha-MHC was suppressed in pressure overload hypertrophy. The switch from alpha- to beta-MHC occurred at the mRNA level. Ca(2+)-ATPase of sarcoplasmic reticulum (SR) is important because it regulates intracellular Ca2+ levels during relaxation. In pressure-overload hypertrophy, the SR Ca(2+)-ATPase was markedly decreased in both the enzyme activities and mRNA levels, while in thyrotoxic hearts both were increased. Interstitial cells also undergo phenotypic modulation which was demonstrated by the induction of nonmuscle-type MHC in pressure-overload hypertrophy. The signal transduction system in cardiac hypertrophy was examined by stretching cardiac myocytes grown on deformable membranes. In our analysis, stretching myocytes stimulated protein kinase C, MAP-II kinase and S6 kinase, all of which may lead to the induction of fetal-type cardiac genes and accelerated protein synthesis. These analyses of subcellular adaptation in cardiac hypertrophy provide important insights into understanding molecular mechanisms of cardiac functions.

Animals↗
PubMed1993

Disappearance of Ph1 chromosome with intensive chemotherapy and detection of minimal residual disease by polymerase chain reaction in a patient with blast crisis of chronic myelogenous leukemia.

We diagnosed a patient with chronic myelogenous leukemia (CML) in chronic phase (CP) on the basis of clinical findings, Ph1 chromosome detected by cytogenetic analysis, and bcr-abl fusion mRNA detected by reverse transcriptase-dependent polymerase chain reaction (RT-PCR). One month after diagnosis, the patient developed extramedullary blast crisis in the lymph nodes, and then medullary blast crisis in the bone marrow, in which different surface markers were shown. Combination chemotherapy with BH-AC, VP16, and mitoxantrone was administered; this resulted in rapid disappearance of the lymphadenopathy, restoration of normal hematopoiesis, and no Ph1 chromosome being detected by cytogenetic analysis. RT-PCR performed to detect the residual Ph1 clone revealed that although the Ph1 clone was preferentially suppressed, it was still residual. The intensive chemotherapy regimen preferentially suppressed the Ph1-positive clone and led to both clinical and cytogenetic remission in this patient with BC of CML; we suggest that RT-PCR is a sensitive and useful method for detecting minimal residual disease during the clinical course of this disease.

Adult↗
PubMed1993

[Production of transgenic mice overexpressing rabbit Na+/H+ antiporter].

Recent investigations have raised a possibility that abnormal ion transportation through cell membranes may be involved in the pathogenesis of essential hypertension. In order to test the hypothesis that increased activity of Na+/H+ antiporter may cause hypertension, we developed transgenic mice overexpressing the Na+/H+ antiporter. We isolated a full-length cDNA clone encoding the rabbit Na+/H+ antiporter and constructed the transgene by ligating it with the human elongation factor 1 alpha promoter. We obtained three transgenic strains which express the transgene in various tissues such as kidney, heart and aorta. These transgenic mice may be useful for the analysis of pathogenesis of essential hypertension.

Animals↗
PubMed1993

Human polymorphonuclear leukocytes have dual effects on endothelin-1: the induction of endothelin-1 mRNA expression in vascular endothelial cells and modification of the endothelin-1 molecule.

The effect of human polymorphonuclear leukocytes (PMNs) on the expression of the endothelin-1 (ET-1) gene and the production of ET-1 peptide was investigated. Human PMNs were separated from venous blood with Mono-Poly Resolving Medium and activated by incubation with formyl-methionyl-lencylphenylalanine (FMLP) (1 microM). Then PMN suspension was added to cultured porcine endothelial cell monolayers and coincubated for various periods. Following the coincubation, ET-1 mRNA in endothelial cells was examined by Northern blotting and immunoreactive ET-1 (irET-1) peptide levels in the conditioned media were measured by an enzyme-linked immunosorbent assay (ELISA). Similar experiments were also carried out with cell-free PMN supernatant. Untreated and activated PMNs led to a 1.4-fold and 6.3-fold increase in ET-1 mRNA levels in endothelial cells, respectively, at 6h, while irET-1 peptide levels did not significantly increase as compared with control. In contrast, when PMNs were coincubated in the presence of an Intercell chamber without direct contact to endothelial cells, PMNs did not induce ET-1 mRNA expression in endothelial cells, and significantly decreased irET-1 peptide levels in the conditioned media. Cell-free PMN supernatant did not have all these effects on ET-1. These findings suggest that direct PMN-endothelial cell contact was essential for PMN-induced expression of the ET-1 gene and that PMNs may decrease irET-1 through some modification of the ET-1 molecule.

Animals↗
PubMed1993

Identification of novel protein-tyrosine phosphatases in a human leukemia cell line, F-36P.

Polymerase chain reaction (PCR) was used to identify protein-tyrosine phosphatases (PTPases) in a human leukemic cell line, F-36P. Degenerate primers deduced from the highly conserved amino acid sequences in the catalytic domain of known PTPases were used for amplification. Among 16 clones sequenced, 13 were identical to known PTPases, whereas the other three clones were disclosed to encode novel PTPases. The expression pattern of one of the three newly identified PTPases, designated as F-36-12, was further analysed. In murine tissues, the F-36-12 message was predominantly expressed in brain, kidney, and intestine, and was weakly expressed in heart and thymus. In human hematopoietic cell lines, the F-36-12 message was preferentially expressed in a promyelocytic leukemic cell line, HL60, and two factor-dependent leukemic cell lines, F-36P and F-36E, that are dependent on granulocyte-macrophage colony-stimulating factor or interleukin-3 and erythropoietin, respectively. The transcript was approximately 8 kb long and the message level in HL60 cells was slightly increased at 24 hours and then slowly declined when treated with dimethyl sulfoxide for granulocyte differentiation, while the message level was rapidly decreased when treated with 12-O-tetradecanoylphorbol 13-acetate for monocyte/macrophage differentiation. These results show that several PTPases including three novel ones are expressed in a human leukemic cell line and that the particular PTPase, F-36-12, might be involved in the differentiation process in HL60 cells.

Amino Acid Sequence↗
PubMed1992

Nonsense mutation of glucokinase gene in late-onset non-insulin-dependent diabetes mellitus.

A nonsense mutation at codon 186 in exon 5 of the gene for glucokinase, an enzyme important for glucose-induced insulin secretion, was identified in a Japanese patient with late-onset non-insulin-dependent diabetes mellitus (NIDDM). All affected members of her family were heterozygous for the mutation and had late-onset NIDDM or impaired glucose tolerance, whereas unaffected members showed normal glucose tolerance. The early insulin response to oral glucose was impaired in affected relatives, but was normal in those unaffected. These findings suggest that the glucokinase mutation raises the set-point of pancreatic beta cells for glucose-induced insulin secretion, leading to abnormal glucose tolerance in some patients with late-onset NIDDM.

Adolescent↗
PubMed1992

Characterization of GLUT3 protein expressed in Chinese hamster ovary cells.

We have expressed GLUT3 protein, an isoform of a facilitative glucose transporter, in Chinese hamster ovary cells by transfection of its cDNA using an expression vector. The expressed GLUT3 protein was detected by Western-blot analysis as a broad band of 45-65 kDa, indicating intensive glycosylation of the protein. The expressed GLUT3 protein was observed, by immunofluorescence staining, to be located mainly at the plasma membrane, and its expression was associated with a marked increase in glucose-transport activity. Kinetic analysis revealed that the Km value of GLUT3 protein for 3-O-methylglucose uptake was approx. 35% of that of GLUT1 protein, whereas the Km value of GLUT3 protein for 2-deoxy-D-glucose uptake was very similar to that of GLUT1 protein. The Vmax. value of GLUT3 protein for 3-O-methylglucose and 2-deoxyglucose uptake was approx. 20-50% of that of GLUT1 protein. GLUT3 protein was well photolabelled with [3H]cytochalasin B or a mannose derivative, 2-N-4-[3H](1-azi-2,2,2-trifluoroethyl)benzoyl-1,3-bis-(D-mannos -4-yloxy)-2- propylamine. Thus GLUT3 protein has very similar characteristics to GLUT1 protein including its subcellular localization, but exhibits lower Km and Vmax. values for 3-O-methylglucose uptake.

3-O-Methylglucose↗
PubMed1992

Replacement of intracellular C-terminal domain of GLUT1 glucose transporter with that of GLUT2 increases Vmax and Km of transport activity.

The intracellular C-terminal domain is diverse in size and amino acid sequence among facilitative glucose transporter isoforms. The characteristics of glucose transport are also divergent, and GLUT2 has far higher Km and Vmax values compared with GLUT1. To investigate the role of the intracellular C-terminal domain in glucose transport, we expressed in Chinese hamster ovary cells the mutated GLUT1 protein whose intracellular C-terminal domain was replaced with that of GLUT2 by means of engineering the chimeric cDNA. Cytochalasin B, for which GLUT2 protein has much lower affinity, bound to this chimeric protein in a fashion similar to GLUT1. In contrast, greater transport activity was observed in this chimeric glucose transporter compared with the wild-type GLUT1 at 10 mM 2-deoxy-D-glucose concentration. The kinetic studies on 2-deoxy-D-glucose uptake revealed a 3.8-fold increase in Km and a 4.3-fold increase in Vmax in this chimeric glucose transporter compared with the wild-type GLUT1. Thus, replacement of the intracellular C-terminal domain confers the GLUT2-like property on the glucose transporter. These results strongly suggest that the diversity of intracellular C-terminal domain contributes to the diversity of glucose transport characteristics among isoforms.

Amino Acid Sequence↗
PubMed1992

Prevention of autoimmune insulitis in nonobese diabetic mice by expression of major histocompatibility complex class I Ld molecules.

Nonobese diabetic (NOD) mice spontaneously develop a T-cell-mediated autoimmune disease that is similar in many respects to insulin-dependent diabetes mellitus in humans. NOD mice were shown to express major histocompatibility complex class I Kd and Db antigens. To examine the possible involvement of major histocompatibility complex class I molecules in the development of autoimmune insulitis, we attempted to express a different type of class I molecule in NOD mice by crossing C57BL/6 mice transgenic for the class I Ld gene with NOD mice. The backcross progeny expressed the Ld antigen on the peripheral blood lymphocytes at a level comparable with that of the BALB/c mice. The cell surface expression of endogenous class I and class II antigens on the peripheral blood lymphocytes was not affected. Analysis of these mice revealed that the expression of the class I Ld antigen significantly reduced the incidence of insulitis at 20 weeks of age. In situ hybridization of a biotinylated probe on mouse chromosomes showed that the Ld transgene was located in the E area of chromosome 6 with which no genetic linkage to insulin-dependent diabetes mellitus was demonstrated. These results suggest that the NOD-type class I molecules are involved in the development of insulitis in NOD mice.

Animals↗
PubMed1992

Biphasic activation of two mitogen-activated protein kinases during the cell cycle in mammalian cells.

We studied mitogen-activated protein kinase (MAPK) activities during the cell cycle of Chinese hamster ovary (CHO) cells using site-specific antibodies against extracellular signal-regulated kinase-1, a 44-kDa MAPK (Boulton, T.G., Yancopoulos, G.D., Gregory, J.S., Slauer, C., Moomaw, C., Hsu, J., and Cobb, M.H. (1990) Science 249, 64-67). These antibodies detected two distinct MAPKs (44- and 42-kDa MAPKs) in CHO cells. CHO cells were arrested at metaphase in the M phase by treatment with nocodazole, and activities of MAPKs were analyzed at specific time points after release from arrest. Immune complex kinase assay and renaturation and phosphorylation assay in substrate-containing gel revealed that both 44- and 42-kDa MAPKs had activities in the G1 through S and G2/M phases and were activated biphasically, in the G1 phase and around the M phase. MAPKs were inactivated in metaphase-arrested cells. The amount of MAPKs did not change significantly in the cell cycle. In the G1, S, and G2/M phases, MAPKs were phosphorylated on both tyrosine and threonine residues and dephosphorylated in metaphase-arrested cells. Our data suggest that MAPKs may play some role in the cell cycle other than G0/G1 transition.

Amino Acid Sequence↗
PubMed1992

Domains responsible for the differential targeting of glucose transporter isoforms.

Facilitative glucose transporter isoforms, GLUT1 and GLUT4, have different intracellular distributions despite their very similar structure. In insulin-responsive tissues such as adipose tissues and muscle, GLUT4 protein resides mainly in the intracellular region in a basal condition and is translocated to the plasma membrane upon stimulation of insulin. In contrast, GLUT1 protein was distributed about equally between plasma membranes and low density microsomal membranes in 3T3-L1 adipocytes. Furthermore, GLUT1 and GLUT4 were reported to be differentially targeted to the plasma membrane and intracellular region, respectively, when expressed in Chinese hamster ovary cells and HepG2 cells. To elucidate the differential intracellular targeting mechanisms, several chimeric glucose transporters in which portions of GLUT4 are replaced with corresponding portions of GLUT1 have been stably expressed in Chinese hamster ovary cells. Immunofluorescence and immunoelectron microscopy as well as measurement of glucose transport activity revealed that two domains of GLUT4, which are not the NH2- or COOH-terminal domain, determine its targeting to the intracellular vesicles. The first domain contains the consensus sequence of the leucine zipper structure, suggesting that a dimer-forming structure of the glucose transporter might be required for its proper targeting. The other domain contains 28 amino acids, nine of which are different between GLUT1 and GLUT4. Immunoelectron microscopy revealed that the chimeric transporters containing both of these two domains of GLUT1, only the first domain of GLUT1, and none of the domains, exhibited a different cellular distribution with approximately 65, 30, and 15% of the transporters apparently on the plasma membrane, respectively. The addition of insulin did not alter the apparent cellular distributions of these chimeric transporters. These domains would be specifically recognized by intracellular targeting mechanisms in Chinese hamster ovary cells.

Animals↗
PubMed1992

Site-directed mutagenesis of GLUT1 in helix 7 residue 282 results in perturbation of exofacial ligand binding.

The structure-function relationship of the HepG2/erythrocyte-type glucose transporter (GLUT1) has been studied by in vitro site-directed mutagenesis. Chinese hamster ovary clones in which glucose transporters were transfected were shown by Western blotting with a GLUT1 anti-COOH-terminal peptide antibody to have expression levels of Gln282----Leu, Asn288----Ile, and Asn317----Ile mutations that were comparable with the wild type. All three mutant GLUT1 clones had high 2-deoxy-D-glucose transport activity compared with a nontransfected clone, suggesting that these residues are not absolutely required for the transport function. We have examined the possibility that the inner and outer portions of the transport pathway are structurally separate by measuring the interaction of the mutant transporters with the inside site-specific ligand cytochalasin B and the outside site-specific ligand 2-N-4-(1-azi-2,2,2-trifluoroethyl)benzoyl-1,3-bis(D-mannos-4 -yloxy)-2- propylamine (ATB-BMPA). All three mutant GLUT1 clones showed high levels of cytochalasin B labeling, and the N288I and N317I mutants showed high levels of ATB-BMPA labeling. In contrast to the transport and cytochalasin B labeling results, the transmembrane helix 7 Gln282----Leu mutant was labeled by ATB-BMPA to a level that was only 5% of the level observed in the wild type. We have confirmed that this mutant was defective in the outer site by comparing the inhibition of wild-type and mutant 2-deoxy-D-glucose transport by the outside site-specific ligand 4,6-O-ethylidene-D-glucose. 4,6-O-Ethylidene-D-glucose inhibited wild-type transport with a Ki of approximately 12 mM, but this was increased to greater than 120 mM in the Gln282----Leu mutant. Thus, of the 3 residues mutated in this study, only glutamine 282 substitution causes a major perturbation in function, and this is a specific and striking reduction in the affinity for the outside site-specific ligands ATB-BMPA and 4,6-O-ethylidene-D-glucose.

Amino Acid Sequence↗