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H Fukui

Publications and source records attributed to H Fukui.

At least 325 records · Page 18Linked to original sources
PubMed1991

Presynaptic localization of histamine H3-receptors in rat brain.

The localization of histamine H3-receptors in subcellular fractions from the rat brain was examined in a [3H] (R) alpha-methylhistamine binding assay and compared with those of histamine H1- and adrenaline alpha 1- and alpha 2-receptors. Major [3H](R) alpha-methylhistamine binding sites with increased specific activities ([3H]ligand binding vs. protein amount) were recovered from the P2 fraction by differential centrifugation. Minor [3H](R)alpha-methylhistamine binding sites with increased specific activities were also detected in the P3 fraction. Further subfractionation of the P2 fraction by discontinuous sucrose density gradient centrifugation showed major recoveries of [3H](R)alpha-methylhistamine binding in myelin (MYE) and synaptic plasma membrane (SPM) fractions. A further increase in specific activity was observed in the MYE fraction, but the SPM fraction showed no significant increase in specific activity. Adrenaline alpha 2-receptors, the pre-synaptic autoreceptors, in a [3H] yohimbine binding assay showed distribution patterns similar to histamine H3-receptors. On the other hand, post-synaptic histamine H1- and adrenaline alpha 1-receptors were closely localized and distributed mainly in the SPM fraction with increased specific activity. Only a negligible amount was recovered in the MYE fraction, unlike the histamine H3- and adrenaline alpha 2-receptors.

Animals↗
PubMed1991

Biochemical characterization of histamine H1 receptors in bovine adrenal medulla.

Bovine adrenal medullary membranes display high affinity and saturable binding to [3H]mepyramine, a selective H1 antagonist, with Kd of 1.5 +/- 0.1 nM and Bmax of 694 +/- 12 fmol/mg protein. [3H]Azidobenzpyramine, an azidobenzamide derivative of mepyramine, was synthesized and used to photolabel the high affinity mepyramine binding sites. Following photolysis, a protein component with an approximate molecular weight of 53-58 kDa was shown to be covalently labeled, as judged by gel filtration and SDS/PAGE; labeling being greatly reduced in the presence of excess unlabeled mepyramine. These results indicate that bovine adrenal medulla expresses a large number of H1 receptors, which are pharmacologically and biochemically indistinguishable from the H1 receptor of many other tissues of various species.

Adrenal Medulla↗
PubMed1991

Histamine-induced inositol phosphate accumulation in type-2 astrocytes.

Histamine elicited dose-dependent accumulation of [3H]inositol phosphates in type-2 astrocytes, but not in type-1 astrocytes. The ED50 was about 2.4 x 10(-6) M and the maximal response was obtained at 10(-4) M. This response was dose-dependently inhibited by H1-antagonists, mepyramine and D- and L-chlorpheniramine. Furthermore, D- and L-chlorpheniramine showed stereoselectivity in the inhibition. On the other hand, an H2-antagonist, famotidine, and an H3-antagonist, thioperamide, did not inhibit the response. These results indicate that histamine stimulates accumulation of inositol phosphates in type-2 astrocytes via H1-receptors.

Animals↗
PubMed1991

Ethanol-induced disturbance of hepatic microcirculation and hepatic hypoxia.

The hypothesis was tested whether ingestion of ethanol might disturb the hepatic microcirculation with resulting hepatic hypoxia. Infusion of ethanol increased the portal pressure concentration-dependently in rat livers perfused with Krebs-Henseleit buffer at a constant flow rate (Emax = 11.5 cm H2O, EC50 = 90 mM). This increase in portal pressure was due to hepatic vasoconstriction, since it diminished in the presence of sodium nitroprusside, a direct acting vasodilator. The regional hepatic tissue hemoglobin concentration after perfusion with added erythrocyte suspension (hematocrit 1%), measured by tissue-reflectance spectrophotometry, was significantly diminished by the infusion of ethanol, indicating the impairment of the microcirculation of the superficial layer of the liver. When the absorption spectrum of the liver was examined by reflectance spectrophotometry, infusion of ethanol caused a parallel reduction of all the mitochondrial respiratory cytochromes in a concentration-dependent fashion, concomitant with the increase of portal pressure, indicating a marked reduction of oxygen concentration in superficial liver tissue. The reduction of the respiratory cytochromes was also associated with the decrease in oxygen consumption of the liver, indicating that the hepatic hypoxia was due to the reduction of oxygen delivery to hepatocytes rather than the increased oxygen consumption of the liver. The reduction of the respiratory cytochromes was correlated with the increase in portal pressure and was inhibited by sodium nitroprusside. These data indicate that the ethanol-induced hepatic vasoconstriction disturbs hepatic microcirculation, resulting in hepatic hypoxia and reduction of mitochondrial respiratory cytochromes.

Animals↗
PubMed1991

Single type-2 astrocytes show multiple independent sites of Ca2+ signaling in response to histamine.

Intracellular Ca2+ plays an important role in signal transduction as a second messenger. In various types of cells, inositol 1,4,5-trisphosphate-induced elevations of intracellular free Ca2+ concentration ([Ca2+]i) have been reported to be uniform in single cells or originate at discrete sites from which they then propagate throughout the cells. These observations so far imply that a single cell functions as a minimal unit for inositol 1,4,5-trisphosphate-induced Ca2+ signaling. In this study, we examined the effects of histamine on [Ca2+]i of type-2 astrocytes using fura-2-based digital imaging fluorescence microscopy and found an unusual type of Ca2+ signaling in these cells. Histamine induced [Ca2+]i elevation in type-2 astrocytes by means of histamine H1 receptors. Submaximal concentrations of histamine (10(-7)-10(-6) M) evoked multiple sites of oscillatory [Ca2+]i elevation in single type-2 astrocytes. These Ca2+ "hot spots" were localized in the processes of the astrocytes but not in the cell bodies. The time courses of [Ca2+]i oscillations in different hot spots were not synchronized, indicating that each of them formed an independent compartment of Ca2+ signaling. When higher concentrations (10(-5)-10(-4) M) of histamine were added, [Ca2+]i in the processes remained elevated at high levels and [Ca2+]i elevations propagated from the processes to the cell bodies. These results suggest that individual processes of type-2 astrocytes can form minimal units for Ca2+ signaling in response to submaximal concentrations of histamine and that single type-2 astrocytes may function as multiple units for Ca2+ signaling.

Animals↗
PubMed1991

Isolation and chemical characterization of two structurally and functionally distinct forms of botrocetin, the platelet coagglutinin isolated from the venom of Bothrops jararaca.

Two distinct forms of botrocetin, the von Willebrand factor (vWF)-dependent platelet coagglutinin isolated from the venom of the snake Bothrops jararaca, were purified and characterized structurally and functionally. The apparent molecular mass of the one-chain botrocetin was 28 kDa before and 32 kDa after reduction of disulfide bonds, while that of the two-chain botrocetin was 27 kDa before and 15/14.5 kDa after reduction. Amino acid composition of the two species revealed a similar high content of potentially acidic residues (greater than 60 Asx and Glx residues/molecule) but significant differences in the content of Cys and Phe residues. The NH2-terminal sequence of the one-chain botrocetin was Ile-Ile/Val-Ser-Pro-Pro-Val-Cys-Gly-Asn-Glu-. Two constituent polypeptides of the two-chain botrocetin showed similar but different NH2-terminal sequences, distinct from that of the one-chain species: (alpha) Asp-Cys-Pro-Ser-Gly-Trp-Ser-Ser-Tyr-Glu- and (beta) Asp-Cys-Pro-Pro-Asp-Trp-Ser-Ser-Tyr-Glu-. The carbohydrate content of both species was less than 2% of the total mass, and the pI was 4.0-4.1 for the one-chain species, and 4.6, 5.3-5.4, and 7.7-7.8 for the two-chain species. No free sulfhydryl group was detected in each species. Both types of botrocetin were resistant to proteolysis at neutral pH. Incubation of 125I-labeled one-chain botrocetin with the crude venom solution resulted in no detectable structural change. On a weight basis, the two-chain botrocetin was 34 times more active than the one-chain form in promoting vWF binding to platelets.(ABSTRACT TRUNCATED AT 250 WORDS)

Amino Acid Sequence↗
PubMed1991

Synaptic and extra-synaptic distribution of histamine H1-receptors in rat and guinea pig brains.

Localization of histamine H1-receptors in subcellular fractions from rat and guinea pig brains was examined in a [3H]mepyramine binding study. Major [3H]mepyramine binding sites with increased specific activities [( 3H]mepyramine binding vs. protein amount) were recovered from P2 fractions from both rat and guinea pig brains by differential centrifugation. Further subfractionation of both rat and guinea pig P2 fractions by a discontinuous sucrose density gradient centrifugation showed the highest recovery of [3H]mepyramine binding with further increased specific activities found in synaptic plasma membrane (SPM) fractions. Minor [3H]mepyramine binding sites with increased specific activities were detected in both rat and guinea pig P3 fractions. [3H]Mepyramine binding sites in SPM and P3 fractions showed identical Kd values in each species. These results indicate that histamine H1-receptors are located not only in synaptic but also in extra-synaptic membranes of both rat and guinea pig brains.

Animals↗
PubMed1991

Studies on anti-von Willebrand factor (vWF) monoclonal antibody NMC-4, which inhibits both ristocetin- and botrocetin-induced vWF binding to platelet glycoprotein Ib.

Anti-von Willebrand factor (vWF) monoclonal antibody NMC-4 completely inhibited vWF binding to platelet glycoprotein (GP) lb induced by either ristocetin or botrocetin at an IgG concentration of approximately 10 micrograms/mL, and also blocked binding of asialo-vWF to GP lb. NMC-4 coupled beads isolated a 97-Kd fragment (Fr) from a whole tryptic digest of vWF. The N-terminal sequencing of the nonreduced 97-Kd Fr, in combination with amino acid analysis, showed it to be a homodimer of residues 449 through 728 of the constituent subunit. Present data, together with the results obtained from previous studies, confirm the existence of one or three possible inter-subunit disulfide bonds between cysteine residues 459, 462, and 464. NMC-4 bound to reduced vWF Fr(s) more weakly than to nonreduced Fr(s), but it did not react with Fr III-T2 of vWF, a disulfide-linked twin heterodimer of residues 273 through 511 and 674 through 728 (Marti et al, Biochemistry 26:8099, 1987). Fr III-T2 completely inhibited ristocetin-induced vWF binding at a concentration of 100 mumol/L but had no effect on botrocetin-induced binding. In addition, both the N- and C-terminal polypeptides, residues 449 through 549 and 674 through 728, generated by subdigestion of the 52/48-Kd Fr (Fujimura et al, J Biol Chem 261:381, 1986), inhibited preferentially ristocetin-induced vWF binding without affecting to botrocetin-induced vWF binding. These findings suggest that amino acid residues 512 through 673 of the vWF subunit are involved in botrocetin-induced vWF binding.

Antibodies, Monoclonal↗
PubMed1991

Flow cytometric analysis of anti-platelet antibodies in patients with chronic idiopathic thrombocytopenic purpura (ITP) using acid-treated, formalin-fixed platelets.

Acid treatment of normal washed platelets prepared by albumin density gradient centrifugation followed by formalin fixation effectively eliminates HLA class I antigens from the platelet surface, without altering the immunoreactivity of platelet membrane glycoproteins Ib and IIb/IIIa complex. Using these platelets, flow cytometric analysis was performed on a total of 20 sera from different patients with chronic ITP, and revealed an inverse linear correlation between the platelet count and the mean fluorescence intensity which represents a relative amount of platelet-bound IgG. These results suggest that acid-treated, formalin-fixed platelets can be used as specimens to detect anti-platelet antibodies to differentiate from those to HLA-class I antigens.

Acids↗
PubMed1991

Histamine H1-receptors on astrocytes in primary cultures: a possible target for histaminergic neurones.

The characteristics of histamine H1-receptors expressed on astrocytes from the cerebral cortex of new born rats were analysed by the [3H]-mepyramine binding assay. The apparent dissociation constant (Kd) was 10.4 nM and the binding capacity (Bmax) of 262 fmol/mg protein. H1-antagonists inhibited the [3H]mepyramine bindings and the isomers of chlorpheniramine showed a stereoselectivity for the inhibition of the bindings. Two distinct populations of cultured astrocytes, type-1 and type-2 astrocytes, were enriched and histamine-induced accumulations of inositol phosphates (IP) and cyclic AMP and histamine-evoked Ca++ signals were examined. Histamine stimulated the accumulation of IP in type-2 astrocytes, but not in type-1 astrocytes. The accumulation of cyclic AMP induced by histamine was observed in type-1 astrocytes, although not in type-2 astrocytes. Histamine-induced Ca++ signals were observed in 17.2% of type-1 astrocytes and in 72.9% of type-2 astrocytes. Histamine-induced Ca++ signals in type-2 astrocytes were antagonized by H1-antagonists, but not by H2- antagonists. Histamine-induced Ca++ signals were classified into 4 patterns, ie. transient, oscillatory, sustained and biphasic. When extracellular Ca++ was omitted or La was added to the extracellular medium, sustained phase of Ca++ signal disappeared and transient and oscillatory patterns were only observed. Phorbol ester inhibited histamine-induced Ca++ signals but pertussis toxin (IAP) and organic voltage dependent Ca++ channel blockers had no effect. Histamine-induced Ca++ elevation appeared initially in processes and then Ca++ wave propagated to the cell soma. Ca++ elevation was observed only in the processes in some cells.

Animals↗
PubMed1991

Hepatitis C virus infection in patients with chronic liver diseases.

Antibodies against hepatitis C (HCV) in 512 patients were measured by an enzyme immunoassay (Ortho-HCV ELISA). The frequency of anti-HCV was 80%, 86%, 85% in nonB (NB) chronic hepatitis (CH), cirrhosis (LC), hepatocellular carcinoma (HCC), respectively; 70%, 90% in alcoholic (AL) LC, HCC; 15%, 33%, 58% in hepatitis B (HB) CH, LC, HCC, respectively. Anti-HCV positive cirrhotics had a shorter survival time and earlier development of HCC than anti-HCV negative cirrhotics. The findings suggest that HCV is a major cause of NB chronic liver diseases and may play a pathogenetic role in AL and HB liver diseases.

Adult↗
PubMed1991

Glucagon-induced alteration of serum bile acid level in patients with liver cirrhosis.

Percent changes in serum total bile acid level after IV administration of 1 mg glucagon were measured in 61 cirrhotics. Thirty-three of 38 cases with Child's grade A disease showed a reduction of total bile acid level at 15 minutes; this level was maintained in the majority of them until 120 minutes. A similar mode of serial changes in total bile acid level was also shown in the cases with Child's grade B disease. On the other hand, only 2 of 10 cases with Child's grade C showed a reduction of total bile acid level at 15 minutes. Reduction of total bile acid level at 15 minutes after glucagon administration was mimicked by infusion of dibutyryl cyclic adenosine monophosphate. However, in 3 of 6 cases with elevated total bile acid level at 15 minutes after glucagon administration, dibutyryl cyclic adenosine monophosphate induced a reduction of total bile acid level. Also, it was confirmed that glucagon enhances the uptake of taurocholate into freshly isolated rat hepatocytes by activating Na(+)-dependent, carrier-mediated membrane transport system and observed that its effect is associated with elevation of Vmax (0.6114 nmol.min-1 x 10(6) cells-1 without glucagon; 0.975 nmol.min-1 x 10(6) cells-1 in glucagon added) but not with affecting Km (13.58 mumol/L without glucagon; 13.71 mumol/L with glucagon) or protein synthesis which is inhibited by cycloheximide. These observations suggest that glucagon enhances Na(+)-coupled membrane transport of bile acids in the liver and causes the reduction of serum total bile acid level and that a lack of this response may be indicative of membrane dysfunction in the liver.

Bile Acids and Salts↗
PubMed1991

Estimation of interleukin 6 production by reverse transcriptase-polymerase chain reaction in four human myeloma cell lines.

Although an autocrine growth mechanism through interleukin 6 has been advocated in human myeloma cells, reports of IL-6 production by cells from established myeloma cell lines are rare. In the present study, we examined whether or not a minute amount of interleukin 6 is produced in 4 human myeloma cell lines. IL-6 production was not detected in any of the 4 lines by enzyme immunoassay, bioassay with two interleukin 6-dependent murine hybridoma cell lines and Northern hybridization. However, we detected interleukin 6 mRNA in one (U266) of the 4 lines by the reverse transcriptase-polymerase chain reaction. Nevertheless, the proliferation of all 4 lines was not inhibited by an anti-interleukin 6 antibody. These results suggest that autocrine stimulation by interleukin 6 is not involved in the majority of human myeloma cell lines.

Base Sequence↗
PubMed1991

Plasma endotoxin concentrations in patients with alcoholic and non-alcoholic liver disease: reevaluation with an improved chromogenic assay.

Plasma endotoxin concentration was measured in 85 patients with alcoholic liver disease (alcoholic cirrhosis (n = 64), alcoholic hepatitis without cirrhosis (n = 11), fatty liver (n = 10), and in patients with non-alcoholic cirrhosis (n = 15]. Endotoxin concentration was determined with an improved chromogenic substrate assay, using individual standard curves for each plasma sample. In patients with alcoholic cirrhosis the mean endotoxin concentration was significantly higher than in patients with non-alcoholic cirrhosis (p less than 0.05). In addition, distinctly higher endotoxin concentrations (greater than 20 pg/ml) were more frequently observed in patients with alcoholic cirrhosis than in non-alcoholic cirrhosis (34.4 vs. 14.3%, p less than 0.05). Mean endotoxin concentration was not significantly higher in cirrhotics with ascites or esophageal varices as compared with the subgroup without ascites or esophageal varices. The endotoxin concentration did not correlate with serum bilirubin, prothrombin concentration or serum enzyme activities. In patients with alcoholic liver disease, however, endotoxin concentration revealed a negative correlation (p less than 0.05) with the concentration of high density lipoprotein cholesterol. On admission endotoxin concentrations in alcoholics with fatty liver were similarly elevated as observed in alcoholic cirrhosis. In six out of 12 patients with fatty liver or alcoholic hepatitis, in whom a second sample of plasma was investigated after 6 to 8 days, endotoxemia was no longer detectable; in the remaining patients, the endotoxin concentration decreased markedly. The results indicate that, irrespective of the stage of liver disease, alcohol abuse favours the development of endotoxemia. They support the hypothesis that gut-derived endotoxins might play a role in the initiation and aggravation of alcohol-induced liver disease.

Adult↗
PubMed1991

Alteration of serum lipoprotein metabolism by polychlorinated biphenyls and methionine in rats fed a soybean protein diet.

The effects of dietary supplementation of methionine to a 20% soybean protein isolate diet on serum lipoprotein profiles and secretion rate of VLDL in rats receiving polychlorinated biphenyls (PCB) were investigated. Serum cholesterol levels were higher in rats fed PCB or a methionine supplement than in controls. The effects of PCB and methionine were synergistic. The feeding of PCB resulted in more cholesterol in all fractions of serum lipoproteins tested, especially HDL (HDL1 and HDL2). Dietary supplementation of methionine primarily increased HDL cholesterol. The elevation of serum lipoprotein cholesterol due to PCB and/or methionine was significant in HDL1, which showed alpha-mobility. These results showed that methionine and PCB significantly influenced HDL metabolism. The secretion rate of VLDL was higher in rats fed PCB than in controls, but the addition of methionine to diets did not affect the secretion rate of VLDL cholesterol. This implies that PCB increased serum cholesterol partly through the stimulation of VLDL cholesterol secretion.

Administration, Oral↗
PubMed1991

Adenosine induces System A amino acid transport in cultured rat hepatocytes.

Adenosine caused a 2.5-fold increase in the sodium-dependent uptake of 2-aminoisobutyric acid in rat hepatocytes in primary culture following incubation for 3 h. The range of stimulating concentrations of adenosine corresponded to that of cAMP formation. Adenosine increased the Vmax of the transport without altering the Km for 2-aminoisobutyric acid. These effects of adenosine were abolished by actinomycin D. N6-L-Phenylisopropyladenosine also caused twofold increase in the amino acid transport. These findings suggest that adenosine induces System A amino acid transport in a transcription-dependent manner, and the P1-purinergic receptors are mainly involved in this action of the nucleoside.

Adenosine↗
PubMed1991

Solid and cystic tumor of the pancreas in an adult male.

A solid and cystic tumor (SCT) was located at the head of the pancreas in a 43-year-old Japanese male, and pancreatoduodenectomy was performed on the suspicion of papillary carcinoma or cystadenocarcinoma of the pancreas. The lesion, which measured 4.5 x 4.5 x 4.0 cm, was clearly demarcated by connective tissue. The cut surface showed solid grayish-white areas with central cystic degenerative changes. The solid areas consisted of small round cells proliferating in a small solid or a pseudopapillary pattern. The tumor cells partially invaded the surrounding normal pancreatic parenchyma. Immunohistochemical studies revealed positive staining for alpha-1-antitrypsin and neuron-specific enolase, but no staining for known pancreatic hormones. Moreover, ultrastructural studies showed the absence of zymogen granules and the presence of anullate lamellae and neurosecretory granules. On the basis of these findings, a diagnosis of SCT of the pancreas was established. In order to clarify the histogenesis and biological behavior of the tumor, it is necessary to accumulate and analyze similar cases, an endeavor which in turn will contribute to the successful management of this disease.

Adult↗