Biomedical subjects

Y Tomiyama

Publications and source records attributed to Y Tomiyama.

At least 19 recordsLinked to original sources

PubMed2006

Critical role of ADP interaction with P2Y12 receptor in the maintenance of alpha(IIb)beta3 activation: association with Rap1B activation.

OBJECTIVE: Platelet integrin alpha(IIb)beta3 plays a crucial role in platelet aggregation, and the affinity of alpha(IIb)beta3 for fibrinogen is dynamically regulated. Employing modified ligand-binding assays, we analyzed the mechanism by which alpha(IIb)beta3 maintains its high-affinity state. METHODS AND RESULTS: Washed platelets adjusted to 50 x 10(3) microL(-1) were stimulated with 0.2 U mL(-1) thrombin or 5 microm U46619 under static conditions. After the completion of alpha(IIb)beta3 activation and granule secretion, different kinds of antagonists were added to the activated platelets. The activated alpha(IIb)beta3 was then detected by fluorescein isothiocyanate (FITC)-labeled PAC1. The addition of 1 mum AR-C69931MX (a P2Y12 antagonist) or 1 mm A3P5P (a P2Y1 antagonist) disrupted the sustained alpha(IIb)beta3 activation by approximately 92% and approximately 38%, respectively, without inhibiting CD62P or CD63 expression. Dilution of the platelet preparation to 500 microL(-1) also disrupted the sustained alpha(IIb)beta3 activation, and the disruption by such dilution was abrogated by the addition of exogenous adenosine 5'-diphosphate (ADP) in a dose-dependent fashion. The amounts of ADP released from activated platelets determined by high-performance liquid chromatography were compatible with the amounts of exogenous ADP required for the restoration. We next examined the effects of antagonists on protein kinase C (PKC) and Rap1B activation induced by 0.2 U mL(-1) thrombin. Thrombin induced long-lasting PKC and Rap1B activation. AR-C69931MX markedly inhibited Rap1B activation without inhibiting PKC activation. CONCLUSIONS: Our data indicate that the continuous interaction between released ADP and P2Y12 is critical for the maintenance of alpha(IIb)beta3 activation.

15-Hydroxy-11 alpha,9 alpha-(epoxymethano)prosta-5↗

PubMed2005

Association of the antagonism of von Willebrand factor but not fibrinogen by platelet alphaIIbbeta3 antagonists with prolongation of bleeding time.

BACKGROUND: The alphaIIbbeta3 antagonists inhibit platelet aggregation and are used as antithrombotic agents for cardiothrombotic disease. The present study investigates the correlation of inhibition of fibrinogen and von Willebrand factor (VWF) binding by alphaIIbbeta3 antagonists with the inhibition of platelet aggregation and prolongation of bleeding time (BT). METHODS: Inhibition of fibrinogen and VWF binding were assessed in a purified alphaIIbbeta3-binding assay. As an in vitro cell-based assay, platelet aggregation and VWF-mediated adhesion studies were performed using human platelets. In vivo effects on BT were measured using a template device in dogs at the same time as an ex vivo aggregation study was performed. RESULTS: In vitro studies demonstrated that the antiaggregatory effects of alphaIIbbeta3 antagonists correlate with their inhibition of fibrinogen binding, but not VWF. Interestingly, the effects of alphaIIbbeta3 antagonists on BT could be differentiated from the inhibition of platelet aggregation. Furthermore, this differentiation was strongly correlated with the different inhibitory potencies between fibrinogen and VWF binding, as well as that between VWF-mediated adhesion and aggregation. CONCLUSIONS: Our study provides novel evidence showing that the inhibitory effect of alphaIIbbeta3 antagonists on VWF, but not fibrinogen binding, correlates with their ability to prolong BT.

Animals↗

PubMed2005

Expression and subcellular localization of WAVE isoforms in the megakaryocyte/platelet lineage.

WAVE isoforms, which consist of WAVE-1, WAVE-2 and WAVE-3, are members of the Wiskott-Aldrich syndrome protein (WASP) family. They are implicated in the regulation of actin-cytoskeletal reorganization downsteam of the small GTPase, Rac. Since platelet attachment to extracellular matrices leads to filopodial and lamellipodial extension, we examined the expression and subcellular localization of WAVEs in platelets. Employing primary megakaryocytic cells derived from cord blood as well as megakaryocytic cell lines, we also examined their expression during megakaryocytic differentiation. Immunoblotting and immunohistochemical analysis revealed that platelets expressed WAVE-1 and WAVE-2, whereas WAVE-3 expression was hardly to be detected. WAVE-1 expression was associated with megakaryocytic differentiation, whereas WAVE-2 and WAVE-3 expression was not changed by the differentiation. In adhered platelets both WAVE-1 and WAVE-2 were localized at the edge of the lamellipodia and at the tips of filopodia. In WASP-deficient platelets we found normal lamellipodial formation and localization of WAVE-1 and WAVE-2 at the edges of lamellipodia. Furthermore, we demonstrated that WAVE-1 and WAVE-2 moved from a detergent-soluble cytosolic fraction to insoluble cytoskeleton fraction after platelet aggregation. These results suggest that WAVE-1 and WAVE-2 regulate actin reorganization during platelet spreading and aggregate formation.

Blood Platelets↗

PubMed2005

Impaired platelet function in a patient with P2Y12 deficiency caused by a mutation in the translation initiation codon.

In this study, we have identified a patient (OSP-1) with a congenital P2Y12 deficiency showing a mild bleeding tendency from her childhood and examined the role of P2Y12 in platelet function. At low concentrations of agonists OSP-1 platelets showed an impaired aggregation to several kinds of stimuli, whereas at high concentrations they showed a specifically impaired platelet aggregation to adenosine diphosphate (ADP). ADP normally induced platelet shape change and failed to inhibit PGE1-stimulated cAMP accumulation in OSP-1 platelets. Molecular genetic analysis revealed that OSP-1 was a homozygous for a mutation in the translation initiation codon (ATG to AGG) in the P2Y12 gene. Heterologous cell expression of wild-type or mutant P2Y12 confirmed that the mutation was responsible for the deficiency in P2Y12. OSP-1 platelets showed a markedly impaired platelet spreading onto immobilized fibrinogen. Real-time observations of thrombogenesis under a high shear rate (2000 s(-1)) revealed that thrombi over collagen were small and loosely packed and most of the aggregates were unable to resist against high shear stress in OSP-1. Our data suggest that secretion of endogenous ADP and subsequent P2Y12-mediated signaling are critical for platelet aggregation, platelet spreading, and as a consequence, for stabilization of thrombus.

Aged↗

PubMed2004

Activation of integrin alpha IIb beta 3 in the glycoprotein Ib-high population of a megakaryocytic cell line, CMK, by inside-out signaling.

Affinity/avidity state of integrin alpha IIb beta 3 is regulated by intracellular inside-out signaling. Although several megakaryocytic cell lines have been established, soluble ligand binding to alpha IIb beta 3 expressed in these cells by cellular agonists has not been demonstrated. We have re-examined agonist-induced alpha IIb beta 3 activation on megakaryocytic cell lines with a marker of the late stage of megakaryocytic differentiation, glycoprotein Ib (GPIb). Activation of alpha IIb beta 3 was assessed by PAC1 and soluble fibrinogen binding to the cells. We found that alpha IIb beta 3 expressed in CMK cells with high GPIb expression was activated by a phorbor ester, phorbol myristate acetate (PMA). Although the population of the GPIbhigh cells was <0.5% of the total cells, incubation with a nucleoside analog, ribavirin, efficiently increased the PMA-reactive GPIbhigh cells. Not only PMA but also a calcium ionophore, A23187, induced alpha IIb beta 3 activation, and PMA and A23187 had an additive effect on alpha IIb beta 3 activation. Ligand binding to the activated alpha IIb beta 3 in the GPIbhigh CMK cells is totally abolished by an alpha IIb beta 3-specific antagonist, and inhibited by wortmannin, cytochalasin-D and prostaglandin E1, and the effects of these inhibitors on alpha IIb beta 3 activation in the GPIbhigh CMK cells were compatible with those in platelets. We have also demonstrated that the ribavirin-treated CMK cells express PKC-alpha, -beta, -delta and -theta, and suggested that PKC-alpha and/or -beta appear to be responsible for PMA-induced activation of alpha IIb beta 3 in CMK cells.

Alprostadil↗

PubMed2003

Successful second allogeneic peripheral blood stem cell transplantation and donor lymphocyte infusion in patients with relapsed acute leukemia using the same donors as for the initial allogeneic bone marrow transplantation.

We report the successful treatment of two acute lympho- blastic leukemia (ALL) patients who relapsed following allogeneic bone marrow transplantation (allo-BMT) with allogeneic peripheral blood sem cell transplantation(allo-PBSCT) and donor lymphocyte infusion (DLI) from the same HLA-identical related donors as those used for the first allo-BMT. The patients relapsed on days 154 and 351 from the initial allo-BMT, respectively. Since conventional reinduction chemotherapy failed, allo-PBSCT was undertaken while the patients were still myelosuppressed immediately after reinduction chemotherapy. To induce and/or enhance GVL effects following allo-PBSCT, we performed rapid tapering of CsA and added DLI. After allo-PBSCT and DLI, the patients maintained their complete remission at 55 and 48 months post allo-PBSCT, respectively. From these findings, allo-PBSCT and DLI may be a useful treatment strategy for acute leukemia relapsing after allo-BMT.

Adult↗

PubMed2002

Lymphomatous polyp of mantle cell type in the duodenum complicated by gastric cancer: a case of trisomy 3 and t(11;14)(q13;q32).

We experienced a rare case of a lymphomatous polyp of mantle cell type forming a polypoid mass lesion in the duodenum bulbous together with advanced gastric cancer. A total gastrectomy was performed, and the specimen revealed atypical small- to medium-sized lymphoid cells with indented nuclei, which infiltrated the Peyer's patch and formed a nodular mass in the lamina propria and submucosa of the duodenum. The lymphoma cells also infiltrated the lymphoid follicle of the gastric mucosa, spleen, and regional lymph node with a typical mantle zone pattern. Flow cytometric analysis of the single cells of the lymph node and immunohistochemistry of a paraffin-embedded specimen revealed that the lymphoma cells expressed surface CD5, CD19, CD20, and nuclear cyclin D1. Chromosomal analysis of this single cell suspension revealed that these lymphoma cells have trisomy 3 in conjunction with t(11;14)(q13;q32), which is frequently seen in mucosa-associated lymphoid tissue lymphomas (MALToma) in the stomach and is also reported in mantle cell lymphoma as a secondary genetic alteration. Our report suggests that trisomy 3 may be a common chromosomal abnormality in lymphomatous polyps of mantle cell type.

Adenocarcinoma↗

PubMed2001

Platelet-associated anti-GPIIb-IIIa autoantibodies in chronic immune thrombocytopenic purpura recognizing epitopes close to the ligand-binding site of glycoprotein (GP) IIb.

Localization of epitopes for platelet-associated (PA) anti-GPIIb-IIIa (alpha(IIb)beta(3)) autoantibodies in chronic immune thrombocytopenic purpura remains elusive. Previous studies suggest that PA antibodies recognize the tertiary structure of intact glycoprotein (GP) IIb-IIIa. To localize their epitopes using antigen-capture enzyme-linked immunosorbent assay (ELISA), the reactivity of 34 PA anti-GPIIb-IIIa antibodies was examined with recombinant GPIIb-IIIa having a defect in ligand-binding sites in either GPIIb or GPIIIa, and no major conformational change was induced: KO variant GPIIb-IIIa was attributed to a 2-amino acid insertion between residues 160 and 161 in the W3 4-1 loop in GPIIb, and CAM variant GPIIb-IIIa was attributed to D119Y in GPIIIa. In one third (11 of 34) of the patients, PA antibodies showed a marked decrease (less than 50%) in reactivity with KO compared with wild-type GPIIb-IIIa. Their reactivity was also impaired against GPIIbD163A-IIIa. In sharp contrast, they reacted normally with CAM GPIIb-IIIa. OP-G2, a ligand-mimetic monoclonal antibody, markedly inhibited their binding to GPIIb-IIIa in patients with impaired binding to KO GPIIb-IIIa, but small GPIIb-IIIa antagonists did not. In addition, a newly developed sensitive ELISA indicated that autoantibodies showing impaired binding to KO are more potent inhibitors for fibrinogen binding. The present data suggest that certain PA anti-GPIIb-IIIa autoantibodies recognize epitopes close to the ligand-binding site in GPIIb, but not in GPIIIa.

Adult↗

PubMed2001

A new IFN-like cytokine, limitin, modulates the immune response without influencing thymocyte development.

A novel IFN-like molecule, limitin, was recently identified and revealed to suppress B lymphopoiesis through the IFN-alphabeta receptor, although it lacked growth suppression on myeloid and erythroid progenitors. Here we have studied diverse effects of limitin on T lymphocytes and compared limitin with previously known IFNs. Like IFN-alpha and -beta, limitin modified immunity in the following responses. It suppressed mitogen- and Ag-induced T cell proliferation through inhibiting the responsiveness to exogenous IL-2 rather than suppressing the production of IL-2. In contrast, limitin enhanced cytotoxic T lymphocyte activity associated with the perforin-granzyme pathway. To evaluate the effect of limitin in vivo, a lethal graft-versus-host disease assay was established. Limitin-treatment of host mice resulted in the enhancement of graft-versus-host disease. Limitin did not influence thymocyte development either in fetal thymus organ cultures or in newborn mice injected with limitin-Ig, suggesting that limitin is distinguishable from IFN-alpha and -beta. From these findings, it can be speculated that the human homolog of limitin may be applicable for clinical usage because of its IFN-like activities with low adverse effects on, for example, T lymphopoiesis, erythropoiesis, and myelopoiesis.

Adjuvants, Immunologic↗

PubMed2001

Reduced adhesion of monocyte-derived macrophages from CD36-deficient patients to type I collagen.

CD36 is an 88-kDa glycoprotein expressed on platelets and monocyte/macrophages (Mphi). CD36 is a multifunctional receptor for collagen, thrombospondin, oxidized low density lipoproteins (LDL), and long-chain fatty acids. The present study was performed to investigate whether CD36 can function as an adhesion molecule which is involved in mediating human macrophages (Mphi) adhesion to type I collagen in vitro. The Mphi of human CD36-deficient as well as normal control subjects were isolated and cultured on the multi-well plates coated with type I collagen, a natural ligand for CD36. Up to 2 h of incubation, the Mphi from CD36-deficient patients showed almost a approximately 55% decrease in adhesion to type I collagen in comparison to those from controls (P < 0.01). However, there was no significant difference in the adhesion thereafter. Furthermore, the addition of antibody against CD36 into the media of control Mphi significantly inhibited the adhesion by approximately 50% (P < 0.05). The addition of oxidized LDL (OxLDL) did not alter adhesion of Mphi from both CD36-deficient and controls. These data suggest that CD36 is involved in the adhesion of Mphi to type I collagen, especially in the early stage of adhesion.

Antibodies, Monoclonal↗

PubMed2001

Molecular detection of metastatic retinoblastoma cells by reverse transcription polymerase reaction for interphotoreceptor retinoid-binding protein mRNA.

BACKGROUND: In the current study, the authors report a 4 year old girl with disseminated retinoblastoma. To find sensitive and specific molecular markers for detection of retinoblastoma cells in blood and marrow, the authors evaluated three photoreceptor-associated gene transcripts by using reverse transcription polymerase chain reaction (RT-PCR). METHOD: Samples of bone marrow and blood were obtained from healthy donors and the patient. RT-PCR was performed to detect the cone alpha'-subunit of cGMP phosphodiesterase (cone alpha'-PDE), the rod beta-subunit of cGMP (rod beta-PDE), and the interphotoreceptor retinoid-binding protein (IRBP) gene transcript in RNA extracted from the samples. RESULTS: While no expression of rod beta-PDE or IRBP was detected in any of the normal samples, expression of cone alpha'-PDE was detected in two out of seven normal marrow samples. Expression of rod beta-PDE was not detected in the patient samples. Expression of IRBP was detected in the patient samples obtained from iliac bone marrow before intensive chemotherapy but not thereafter. CONCLUSION: RT-PCR for IRBP was a useful method for detecting metastatic retinoblastoma cells as well as for evaluating the therapeutic effects of treatment in this particular case.

Antineoplastic Combined Chemotherapy Protocols↗

PubMed2001

Ligand binding to integrin alpha(v)beta(3) requires tyrosine 178 in the alpha(v) subunit.

Integrin alpha(v)beta(3) has been implicated in angiogenesis and other biological processes. However, the ligand-binding sites in alpha(v), a non-I-domain alpha subunit, remain to be identified. Recently in alpha(IIb), the other partner of the beta(3) subunit, several discontinuous residues important for ligand binding were identified in the predicted loops between repeats 2 and 3 (W3 4-1 loop) and within repeat 3 (W3 2-3 loop). Based on these findings, alanine-scanning mutagenesis in 293 cells was used to investigate the role of these loops (cysteine [C]142-C155 and glycine [G]172-G181) of alpha(v) in ligand binding. Wild-type alpha(v)beta(3) was able to bind soluble fibrinogen following integrin activation either by 0.5 mM manganese dichloride (MnCl(2)) or a mutation of beta(3) threonine (T)562 to asparagine. However, mutation of tyrosine (Y)178 to alanine in the predicted G172-G181 loop of alpha(v) abolished fibrinogen binding, and alanine (A) substitutions at adjacent residues phenylalanine (F)177 and tryptophan (W)179 had a similar effect. Cells expressing Y178Aalpha(v) also failed to bind to immobilized fibrinogen. Moreover, the Y178A mutation abolished the binding of WOW-1 Fab, a monovalent ligand-mimetic anti-alpha(v)beta(3) antibody, and the expression of beta(3) ligand-induced binding sites (LIBS) induced by arginine-glycine-aspartic acid-tryptophan (RGDW). In sharp contrast to the data obtained with alpha(IIb), none of the mutations in the predicted W3 4-1 loop in alpha(v) impaired ligand binding. These results implicate alpha(v) Y178 in ligand binding to alpha(v)beta(3), and they suggest that there are key structural differences in the adhesive ligand-binding sites of alpha(v)beta(3) and alpha(IIb)beta(3).

Amino Acid Sequence↗

PubMed2001

Limitin: an interferon-like cytokine without myeloerythroid suppressive properties.

Limitin is an interferon (IFN)-like cytokine that we recently identified and cloned on the basis of its ability to arrest the growth or kill lympho-hematopoietic cells. This 182 amino acid protein has approximately 30% sequence identity with IFN-alpha, IFN-beta, and IFN-omega. Limitin binds to the IFN-alpha/beta receptors and induces IFN regulatory factor-1, thereby indicating that limitin constitutes a new prototype of the type I IFN family. As with previously known IFNs, limitin inhibited B lymphopoiesis in vivo as well as in vitro. In addition, limitin not only modified the proliferation and function of peripheral T lymphocytes, natural killer cells, and bone marrow stromal cells but also had antiviral activity. Therefore, limitin is a multifunctional cytokine with several potential cellular targets. Because to date we have found no influence of limitin on normal myeloid and erythroid progenitors, limitin is unique among the IFNs. Type I IFN family contains IFN-alpha, IFN-beta, IFN-omega, and IFN-tau, and IFN-alpha is composed of at least 14 subtypes. All IFNs have anti-proliferative, immunomodulatory, and antiviral effects and influence to each other in the body. Limitin should play a role in the complex IFN network, and its human homologue would be useful as a therapeutic agent if it lacked myelosuppressive activity.

Animals↗

PubMed2001

Analyses of genetic abnormalities in type I CD36 deficiency in Japan: identification and cell biological characterization of two novel mutations that cause CD36 deficiency in man.

To elucidate genetic abnormalities in type I CD36 deficiency, we analyzed 28 Japanese subjects whose platelets and monocytes/macrophages lacked CD36 on their surface. We identified two novel mutations in the CD36 gene. One was a complex deletion/insertion mutation, in which 3 bp, GAG, were deleted at nucleotide (nt) 839-841, and 5 bp, AAAAC, were inserted at the same position (839-841del-->insAAAAC). Mutation 839-841del-->insAAAAC led to a frameshift and appearance of a premature stop codon; it was also accompanied with a marked reduction in the amount of CD36 mRNA. The other was a 12-bp deletion at nt 1438-1449 (1438-1449del) accompanied with or without skipping of exon 9 (nt 959-1028). Mutation 1438-1449del led to an inframe 4-amino-acid deletion, whereas exon 9 skipping led to a frameshift and the appearance of a premature stop codon. Expression assay revealed that both 1438-1449del and exon 9 skipping directly caused impairment of the surface expression of CD36. A survey of the five known mutations including 839-841del-->insAAAAC and 1438-1449del in type I CD36-deficient subjects demonstrated that the five mutations covered more than 90% of genetic defects among them and that the substitution of T for C at nt 478 (478C-->T) was the most common mutation with more than 50% frequency. However, none of the four subjects that possessed isoantibodies against CD36 had 478C-->T, suggesting that 478C-->T prevents the production of isoantibodies against CD36.

Alleles↗

PubMed2001

Type I interferons and limitin: a comparison of structures, receptors, and functions.

The type I interferon (IFN) family includes IFN-alpha, IFN-beta, IFN-pi, and IFN-tau. These molecules are clustered according to sequence homologies, use of the same cell surface receptor, and similar functions. IFN-alpha and IFN-beta have a globular structure composed of five a-helices. Their receptors, IFNAR1 and IFNAR2, belong to the class II cytokine receptor family for a-helical cytokines. Information about structure-function relationships between these and other IFNs is being provided by comparative sequence analysis, reference to a prototypic three-dimensional structure, analysis with monoclonal antibodies, construction of hybrid molecules and site directed mutagenesis. While much remains to be done, it should someday be possible to understand differences among IFNs in terms of how they interact with their corresponding receptors. Our recently identified IFN-like molecule, limitin, has weak sequence homology to IFN-alpha, IFN-beta, and IFN-omega and displays its biological functions through the same IFN-alpha/beta receptors. While limitin has antiproliferative, immunomodulatory, and antiviral effects like IFN-alpha and IFN-beta, it is unique in lacking influence on myeloid and erythroid progenitors. Further analysis of this functionally unique cytokine should be informative about complex IFN-receptor interactions. Furthermore, a human homologue or synthetic variant might be superior for clinical applications as an IFN without myelosuppressive properties.

Amino Acid Sequence↗

PubMed2001

Secondary sclerosing cholangitis and portal hypertension after O157 enterocolitis: Extremely rare complications of hemolytic uremic syndrome.

The authors experienced an extremely rare case of secondary sclerosing cholangitis and portal hypertension developed as late complications of hemolytic uremic syndrome (HUS) owing to Escherichia coli O157:H7 in a 2-year-old boy. HUS after E coli O157 infection is the most frequent cause of acute renal failure in childhood and occasionally is accompanied by extrarenal complications such as encephalopathy, cardiomyopathy, ischemic colitis, and pancreatitis. Rarely, late colonic stenosis may develop secondary to the ischemic damage. Sclerosing cholangitis and subsequent cirrhosis with portal hypertension are very uncommon as late complications of HUS. To our knowledge, such a case has not been previously reported in the literature. J Pediatr Surg 36:1838-1840.

Child, Preschool↗

PubMed2001

Lidocaine and mexiletine inhibit mitochondrial oxidation in rat ventricular myocytes.

BACKGROUND: Accumulating evidence suggests that mitochondrial rather than sarcolemmal adenosine triphosphate-sensitive K+ (K(ATP)) channels may have an important role in the protection of myocardium during ischemia. Because both lidocaine and mexiletine are frequently used antiarrhythmic drugs during myocardial ischemia, it is important to investigate whether they affect mitochondrial K(ATP) channel activities. METHODS: Male Wistar rats were anesthetized with ether. Single, quiescent ventricular myocytes were dispersed enzymatically. The authors measured flavoprotein fluorescence to evaluate mitochondrial redox state. Lidocaine or mexiletine was applied after administration of diazoxide (25 microM), a selective mitochondrial K(ATP) channel opener. The redox signal was normalized to the baseline flavoprotein fluorescence obtained during exposure to 2,4-dinitrophenol, a protonophore that uncouples respiration from ATP synthesis and collapses the mitochondrial potential. RESULTS: Diazoxide-induced oxidation of flavoproteins and the redox changes were inhibited by 5-hydroxydecanoic acid, a selective mitochondrial K(ATP) channel blocker, suggesting that flavoprotein fluorescence can be used as an index of mitochondrial oxidation mediated by mitochondrial K(ATP) channels. Lidocaine (10(-3) to 10 mM) and mexiletine (10(-3) to 10 mM) reduced oxidation of the mitochondrial matrix in a dose-dependent manner with an EC50 of 98+/-63 microM for lidocaine and 107+/-89 microM for mexiletine. CONCLUSIONS: Both lidocaine and mexiletine reduced flavoprotein fluorescence induced by diazoxide in rat ventricular myocytes, indicating that these antiarrhythmic drugs may produce impairment of mitochondrial oxidation mediated by mitochondrial K(ATP) channels.

Adenosine Triphosphate↗

PubMed2001

Different distribution patterns of the two mannose 6-phosphate receptors in rat liver.

Two mannose 6-phosphate receptors, cation-dependent and -independent receptors (CDMPR and CIMPR), play an important role in the intracellular transport of lysosomal enzymes. To investigate functional differences between the two in vivo, their distribution was examined in the rat liver using immunohistochemical techniques. Positive signals corresponding to CIMPR were detected intensely in hepatocytes and weakly in sinusoidal Kupffer cells and interstitial cells in Glisson's capsule. In the liver acinus, hepatocytes in the perivenous region showed a more intense immunoreactivity than those in the periportal region. On the other hand, positive staining of CDMPR was detected at a high level in Kupffer cells, epithelial cells of interlobular bile ducts, and fibroblast-like cells, but the corresponding signal was rather weak in hepatocytes. In situ hybridization analysis also revealed a high level of expression of CIMPR mRNAs in hepatocytes and of CDMPR mRNA in Kupffer cells. By double immunostaining, OX6-positive antigen-presenting cells in Glisson's capsule were co-labeled with the CDMPR signal but were only faintly stained with anti-CIMPR. These different distribution patterns of the two MPRs suggest distinct functional properties of each receptor in liver tissue.

Animals↗