Biomedical subjects

S Mochida

Publications and source records attributed to S Mochida.

At least 55 records · Page 3Linked to original sources

PubMed1996

Increased expressions of vascular endothelial growth factor and its receptors, flt-1 and KDR/flk-1, in regenerating rat liver.

Sinusoidal endothelial cells proliferate following hepatocyte regeneration in the liver after partial resection. The expressions of vascular endothelial growth factor (VEGF) and its receptors, flt-1 and KDR/flk-1, were studied by Northern blotting in isolated rat liver cells and 70% resected rat liver. VEGF was expressed in hepatocytes immediately after isolation, and both flt-1 and KDR/flk-1 were expressed in non-parenchymal cells including sinusoidal endothelial cells. The VEGF expression in hepatocytes decreased during primary culture for 48 hr. This expression was maintained at 48 hr of culture by addition of EGF to the medium at 24 hr, increasing thereafter. VEGF, flt-1, and KDR/flk-1 were also expressed in normal rat liver. In 70% resected rat liver, VEGF expression increased with a peak at 72 hr after the operation, followed by expressions of flt-1 and KDR/flk-1 increasing between 72 and 168 hr. These results suggest that VEGF expression increases in regenerating hepatocytes, which may contribute to proliferation of sinusoidal endothelial cells of rat liver following partial resection, probably through flt-1 and KDR/flk-1 receptors upregulated on sinusoidal endothelial cells.

Animals↗

PubMed1996

Instability of Rts1 (drug-resistant factor) replicon: stabilization by DNA fragments derived from Rts1.

Rts1 is a large naturally occurring plasmid which has a kanamycin resistance gene and exhibits various temperature-sensitive phenotypes. A smaller derivative of plasmid, pOK, contains the Rts1 replicon and the kanamycin resistance gene of Rts1. This plasmid, pOK, is much more unstable than Rts1 at 42.5 degrees C. A DNA fragment, G3, 1590 nucleotides long from Rts1 DNA, stabilized pOK completely at 42.5 degrees C but only in the cis configuration. G3 did not change the copy number of pOK. The pOK derivative containing G3 was destabilized by the presence of a compatible plasmid containing G3. G3 has four inverted repeats, two 14-base direct repeats, and three ORFs. Smaller fragment of G3 also had a stabilization effect and these studies showed that the ORF does not play any role in stabilization.

Base Sequence↗

PubMed1996

Inhibition of neurotransmission by peptides containing the synaptic protein interaction site of N-type Ca2+ channels.

N-type Ca2+ channels bind directly to the synaptic core complex of VAMP/synaptobrevin, syntaxin, and SNAP-25. Peptides containing the synaptic protein interaction ("synprint") site caused dissociation of N-type Ca2+ channels from the synaptic core complex. Introduction of synprint peptides into presynaptic superior cervical ganglion neurons reversibly inhibited synaptic transmission. Fast EPSPs due to synchronous transmitter release were inhibited, while late EPSPs arising from asynchronous release following a train of action potentials were increased and paired-pulse facilitation was increased. The corresponding peptides from L-type Ca2+ channels had no effect, and the N-type peptides had no effect on Ca2+ currents through N-type Ca2+ channels. These results are consistent with the hypothesis that binding of the synaptic core complex to presynaptic N-type Ca2+ channels is required for Ca2+ influx to elicit rapid, synchronous neurotransmitter release.

Animals↗

PubMed1996

Role of adhesion molecules in the development of massive hepatic necrosis in rats.

Massive hepatic necrosis develops after endotoxin administration in rats pretreated with heat-killed Propionibacterium acnes as a result of microcirculatory disturbance caused by endothelial cell destruction by activated macrophages in the hepatic sinusoids. Immunohistochemical hepatic expression of intercellular adhesion molecule-1 (ICAM-1) and lymphocyte function-associated antigen 1 alpha (LFA-1 alpha) and the effect of monoclonal antibodies against both adhesion molecules on liver necrosis provoked after endotoxin administration was studied in these rats. There were increased stains of ICAM-1 in endothelial cells and LFA-1 alpha in macrophages in the hepatic sinusoids in Propionibacterium acnes-pretreated rats compared with normal rats. Such stains were further increased soon after endotoxin administration, followed by development of hepatic necrosis. Monoclonal antibodies against both adhesion molecules significantly attenuated the extent of liver injury compared with controls, without affecting the infiltration and activation of hepatic macrophages. Polyclonal antibodies against polymorphonuclear leukocytes eradicated circulating neutrophils, but did not change such liver injury, although gum arabic, which suppressed macrophage activation, attenuated the extent of liver injury. Thus, adhesion between endothelial cells and activated macrophages in the hepatic sinusoids via ICAM-1 and LFA-1 alpha is essential for the initiation of massive hepatic necrosis of this type. Contribution of neutrophils seems less likely.

Animals↗

PubMed1996

Effect of alcohol intake on the efficacy of interferon therapy in patients with chronic hepatitis C as evaluated by multivariate logistic regression analysis.

The effect of alcohol intake on the efficacy of interferon (IFN) therapy was evaluated retrospectively in patients with chronic hepatitis C diagnosed by liver histology and positive serum hepatitis C virus (HCV)-RNA. Patients included 119 given IFN therapy and 11 no IFN therapy. Serum HCV-RNA was measured 6 months after discontinuation of IFN therapy in 92 treated patients, 27.2% of whom showed disappearance of serum HCV-RNA. Multivariate logistic regression analysis revealed that this disappearance was affected by alcohol intake, the presence of its history (p < 0.05) or cumulative alcohol consumption (kg) (p < 0.01), and serum HCV-RNA levels (p < 0.001). The odds ratio associated with serum HCV-RNA still positive at 6 months was 7.018 (95% confidence interval: 1.444-34.062) and 1.004 (1.001-1.007) for the presence of alcohol intake history and the cumulative alcohol consumption, respectively. Other predictor variables-such as sex and age of patients, history of blood transfusion, HCV genotype, histological findings of the liver, and types of IFN-had no influence on the efficacy of the therapy. Cumulative alcohol consumption showed a negative correlation with serum HCV-RNA levels pretreatment, when the outcome variable was divided into two categories based on serum HCV-RNA levels: 10(6) copy/ml or less and 10(7) copy/ml or more. Alcohol intake was positively correlated with histological extent of alcoholic fibrosis, but affected neither grading nor staging of chronic viral hepatitis. We conclude that alcohol intake was a risk factor on the efficacy of IFN therapy in chronic hepatitis C patients. This effect was independent of serum HCV-RNA levels and histological findings specific for viral hepatitis in the liver.

Adult↗

PubMed1995

Blood coagulation equilibrium in rat liver microcirculation as evaluated by endothelial cell thrombomodulin and macrophage tissue factor.

The regulatory mechanisms of microcirculation might differ in the liver from other organs, because macrophages are resident in the hepatic sinusoids and sinusoidal endothelial cells are unique in shape and function. Thrombomodulin expression in endothelial cells and tissue factor activity in isolated macrophages were studied in the liver and lung of rats. In normal rats, the thrombomodulin expression was minimal in hepatic sinusoids, but prominent in pulmonary capillaries, while the tissue factor activity in the presence of endotoxin was higher in pulmonary macrophages than in Kupffer cells, although the levels in the absence of endotoxin were comparable in both cells. The tissue factor activity in hepatic macrophages was increased after priming of the cells with Corynebacterium parvum or after induction of liver necrosis or cirrhosis with carbon tetrachloride. In the necrotic or cirrhotic liver, increased thrombomodulin expression was seen along capillaries extending in necrotic areas and regenerating nodules, but this increase was minimal in the Corynebacterium parvum-treated rat liver. Blood coagulation equilibrium in microcirculation regulated by endothelial cells and macrophages may differ between the liver and lung. Such equilibrium in the liver may vary depending on pathological status.

Animals↗

PubMed1995

ICAM-1 expression in hepatocytes following dissociation of cell-to-cell contact in rats.

ICAM-1 was not detected immunohistologically in hepatocytes in normal rats, but detectable in centrilobular degenerative hepatocytes in carbon tetrachloride-intoxicated rats. ICAM-1 expression was observed even in normal hepatocytes following liver perfusion with Hank's balanced salt solution at a flow rate of 4.2 mL/g liver weight/min or with the same solution containing collagenase or EGTA at the physiological flow rate (1.4 mL/g liver weight/min). Such expression was also observed when liver perfusion was performed after pretreatment of rats with cycloheximide. On electron microscopy, ICAM-1 was exclusively stained on hepatocyte plasma membrane that was detached from the plasma membrane of adjacent hepatocytes. ICAM-1 mRNA and ICAM-1 protein were detected in hepatocytes freshly isolated from normal rats. Thus, ICAM-1 expression in degenerative hepatocytes as well as in hepatocytes following liver perfusion can be assumed to result from dissociation of cell-to-cell contact.

Animals↗

PubMed1995

Use of prostaglandin I2 analog in treatment of massive hepatic necrosis associated with endothelial cell injury and diffuse sinusoidal fibrin deposition.

Endothelial cell damage causes massive hepatic necrosis as a result of fibrin deposition in the hepatic sinusoids. When a stable analog of prostaglandin I2, beraprost sodium, was administered to rats given either dimethylnitrosamine, carbon tetrachloride, or endotoxin following Corynebacterium parvum administration, the hepatic necrosis produced in each was attenuated, but to a greater extent in the dimethylnitrosamine and endotoxin/Corynebacterium parvum models, where fibrin deposition in the hepatic sinusoids occurs, as compared to the carbon tetrachloride model, where such fibrin deposition does not occur. Beraprost sodium reduced the expected increase of portal venous pressure in the endotoxin/Corynebacterium parvum model without affecting plasma thrombin-antithrombin III complex levels. Beraprost sodium also significantly reduced cell killing of both isolated rat hepatocytes and hepatic sinusoidal endothelial cells exposed to tert-butyl hydroperoxide when compared to controls. Beraprost sodium could prove to be a therapeutic candidate for the treatment of hepatic necrosis, particularly in cases associated with fibrin deposition in the hepatic sinusoids because of its fibrin clot-clearing action.

Animals↗

PubMed1995

Impairment of syntaxin by botulinum neurotoxin C1 or antibodies inhibits acetylcholine release but not Ca2+ channel activity.

The involvement of syntaxin, an omega-conotoxin-sensitive Ca2+ channel-associated protein, in acetylcholine release was studied at synapses formed between rat sympathetic neurons in culture. Transmission at these synapses involved omega-conotoxin-sensitive Ca2+ channels because a dose-dependent inhibition was observed when omega-conotoxin was bath-applied. Confocal microscope examination of immunofluorescent staining showed that syntaxin had a similar distribution to synaptic vesicle-associated membrane proteins, synaptophysin and vesicle-associated membrane protein/synaptobrevin-2, indicating that syntaxin molecules are concentrated in the presynaptic terminals. Botulinum neurotoxin C1 applied extracellularly or intracellularly into presynaptic neurons blocked synaptic transmission. Introduction of a monoclonal antibody, or polyclonal antibodies, to syntaxin into the presynaptic neuron depressed the evoked release of acetylcholine without affecting Ca2+ influx through Ca2+ channels. These results suggest that syntaxin plays an important role in release of neurotransmitter by a nerve impulse and that this mechanism is downstream of Ca2+ influx.

Acetylcholine↗

PubMed1995

Regulation of hepatic macrophage function by oral administration of xiao-chai-hu-tang (sho-saiko-to, TJ-9) in rats.

The effect of Xiao-Chai-Hu-Tang (Sho-saiko-to, TJ-9), the extract of a mixture of 7 herbs, on hepatic macrophage function was studied using rats. Hepatic macrophages were activated by injection of Corynebacterium parvum or 70% partial hepatectomy. Oral administration of TJ-9 for 3 weeks did not affect the ability of these macrophages to produce superoxide anions evaluated in situ by liver perfusion with nitro blue tetrazolium (NBT) and phorbol myristate acetate (PMA). However, the similar administration of TJ-9 attenuated the blocking of the activation after partial hepatectomy produced by pretreatment with gum arabic, a polysaccharide of high molecular weight. When gum arabic was added to the medium of rat hepatic macrophages cultured with normal rat sera, their ability to produce superoxide anions was reduced in a dose-related manner. This reduction was attenuated by changing the sera to the sera obtained from rats given oral doses of TJ-9 for 3 weeks. These results suggest that TJ-9 may improve the blocked function of hepatic macrophages in activation.

Administration, Oral↗

PubMed1995

Role of myosin in neurotransmitter release: functional studies at synapses formed in culture.

To determine the functional role of presynaptic proteins in the neurotransmitter release, I have employed cholinergic synapses formed between superior cervical ganglion neurons in culture. These synapses expressed proteins characteristic of mature synapses: immunofluorescence staining showed the presence of synaptophysin, synaptotagmin, VAMP/synaptobrevin-2, syntaxin and neurexin. The function of these proteins seems to be similar to that of mature synapses because botulinum neurotoxins A, E and C1 inhibited neurotransmitter release evoked by presynaptic action potentials. With this preparation, I have obtained evidence supporting roles for myosin II and myosin light chain kinase in neurotransmitter secretion. Acetylcholine release was inhibited by introduction of antibody against myosin II or inhibitors of myosin light chain kinase. This evidence suggests a model in which myosin light chain kinase phosphorylates myosin, and the resultant change in actin-myosin interactions is involved in some steps of transmitter release.

Action Potentials↗

PubMed1995

Detection of allergen-induced genes in peripheral blood mononuclear cells of patients with allergic asthma using subtractive hybridization.

When stimulated with mite antigens, peripheral blood mononuclear cells obtained from patients with mite allergy release eosinophil chemotactic factor, a type of protein. Complementary DNA libraries were formulated from both peripheral blood mononuclear cells stimulated with mite antigens and those not stimulated with mite antigens and underwent subtraction and differential screening. The authors obtained 13 genes for which expression had increased because of mite antigens. Of these, nine were mitochondrial genes; two, h-satellite DNA III; one, factor XIII; and one, ferritin heavy subunit. As a result of polymerase chain reaction on both cDNA libraries, IL-5 genes were amplified only from the cDNA library that had been stimulated with mite antigens.

Allergens↗

PubMed1995

Role of adhesion between activated macrophages and endothelial cells in the development of two types of massive hepatic necrosis in rats.

Sinusoidal endothelial cell damage is produced by activation of hepatic macrophages after endotoxin administration in rats pretreated with Cornyebacterium parvum or undergoing 70% hepatectomy. Such damage causes fibrin deposition in the hepatic sinusoids leading to massive hepatic necrosis. In the C. parvum model, cytotoxic mediators, such as tumour necrosis factor (TNF)alpha and superoxide anions released from activated hepatic macrophages directly destroy sinusoidal endothelial cells. In contrast, in the partial hepatectomy model, endothelial cell damage occurs as a result of fibrin deposition due to derangement of the coagulation equilibrium regulated by tissue factor and thrombomodulin expressed on hepatic macrophages and sinusoidal endothelial cells, respectively. Immunohistological examination revealed that the expression of ICAM-1 in sinusoidal endothelial cells and LFA-1 in hepatic macrophages was greater in both models than in normal rats preceding the development of hepatic necrosis. The extent of liver injury was significantly attenuated by treatment with monoclonal antibodies against both adhesion molecules in the C. parvum model, but aggravated in the partial hepatectomy model, compared to control rats. We conclude that adhesion of activated macrophages to endothelial cells via LFA-1 and ICAM-1 in the hepatic sinusoids is essential for endothelial cell destruction in the C. parvum model, but can act protectively against provocation of fibrin deposition in the hepatectomy model.

Animals↗

PubMed1995

Possible cause of primary graft non-function after orthotopic liver transplantation: a hypothesis with rat models.

The cause of primary graft non-function after orthotopic liver transplantation (OLTX) is uncertain, but its clinical features are similar to fulminant hepatic failure with coagulopathy. In preserved livers, endothelial cell damage in the hepatic sinusoids is characteristic, indicating that fibrin deposition in the hepatic sinusoids, which can cause massive hepatic necrosis, might occur in the liver after OLTX. When rat liver was preserved in University of Wisconsin solution at 1 degree C, detachment of endothelial linings into sinusoidal lumens developed with fat-storing cell damage after 18 h. In this liver, hepatic macrophages were activated after reperfusion. Tissue factor activity in hepatic macrophages isolated from livers after OLTX was significantly increased compared to the control liver and this increase was enhanced by addition of endotoxin. In the preserved and transplanted livers, thrombomodulin expression in endothelial cells disappeared and fibrin deposition was seen in the hepatic sinusoids. Intravenous infusion therapy with antithrombin III attenuated liver injury 24 h after OLTX following preservation for 18 h. These results suggest that intravascular coagulation in the hepatic sinusoids associated with liver injury occurs in the liver after OLTX following cold preservation. This coagulopathy may be caused by sinusoidal endothelial cell damage due to regulatory imbalance in coagulation as a result of increased tissue factor activity in hepatic macrophages and decreased thrombomodulin activity in sinusoidal endothelial cells. Fat-storing cell damage may also contribute to the endothelial cell damage. A hypothesis regarding the cause of primary graft non-function after OLTX is proposed.

Adenosine↗

PubMed1994

Analysis of the mechanism for acetylcholine release at the synapse formed between rat sympathetic neurons in culture.

Superior cervical ganglion neurons (SCGNs) were isolated from 7-day-old rat SCG and cultured in MEM containing horse serum, fetal calf serum, and nerve growth factor. In this culture condition, it is well known that the SCGNs form cholinergic synapse. In 3-4 weeks cultured neurons, immunofluorescent staining for synaptophysin, a small synaptic vesicle associated protein, showed the presence of synaptophysin as small dots on the surface of the soma. Postsynaptic potentials could be recorded in 50-80% of the neurons responding to evoked action potentials elicited in neighboring neurons. Because of its relatively large cell size and the short distance to the terminal, this synapse is a useful model for studying the mechanisms of acetylcholine (ACh) release by introducing substances such as antibodies or selective inhibitors into the presynaptic neuron by means of the whole-cell clamp technique. In this model synapse we tested the possible role of myosin in ACh release. The distribution of myosin was studied by the immunofluorescent staining technique. Myosin was recognized by the anti-myosin II IgG at the same synaptic terminals that showed the presence of synaptophysin with its antibody. The functional blockade of myosin by the antibody itself, and that of myosin light chain kinase (MLCK) by a pseudosubstrate inhibitor of MLCK, SM-1, or by a selective inhibitor of MLCK, wortmannin, induced depression of synaptic transmission in a dose-dependent manner. These indicate that phosphorylation of myosin by MLCK may be necessary for ACh release mechanisms.

Acetylcholine↗

PubMed1994

Fat-storing cell abnormalities associated with endothelial cell damage after cold ischemic storage of rat liver in UW solution.

Rat liver was stored at 1 degree C in University of Wisconsin solution, and morphological changes were observed after 12, 18, 24, and 36 hr by transmission electron microscopy. There were two types of endothelial cell damage in the hepatic sinusoids. One was disruption of the endothelial linings, and the other detachment of endothelial cells into the sinusoidal space accompanied by fat-storing cell abnormalities. The former damage was seen after storage longer than 12 hr, while the latter developed after 18 hr even in the hepatic sinusoids with no disruption of the linings. Considering that fat-storing cell damage can produce endothelial cell destruction, this damage should be given attention as one of factors of endothelial cell destruction in the hepatic sinusoids after cold storage of the liver.

Adenosine↗

PubMed1994

Myosin II is involved in transmitter release at synapses formed between rat sympathetic neurons in culture.

The presynaptic function of myosin II was studied at cholinergic synapses formed between rat superior cervical ganglion neurons in culture. Immunofluorescent staining showed that myosin II was colocalized with synaptophysin at the presynaptic nerve terminals. Antimyosin II antibody introduced into presynaptic neurons inhibited synaptic transmission. Transmission was also inhibited in a dose-dependent manner by two inhibitors of myosin light chain kinase: a peptide, SM-1, and an organic inhibitor, wortmannin. The inhibition produced by these agents was dependent on presynaptic activity. Extracellularly applied wortmannin also blocked synaptic transmission, but its effects were slower in onset. Wortmannin also decreased postsynaptic potentials and post-tetanic potentiation in intact superior cervical ganglia. These results suggest a model in which myosin light chain kinase phosphorylates myosin, and the resultant change in actin-myosin interactions is involved in neurotransmitter release.

Acetylcholine↗

PubMed1994

Oxidative stress in hepatocytes and stimulatory state of Kupffer cells after reperfusion differ between warm and cold ischemia in rats.

Rat liver was kept at 4 degrees C or 37 degrees C in MEM, and reperfused through a closed circulation from the hepatic vein to the portal vein at 37 degrees C with the same solution. Although purine nucleoside phosphorylase and ALT activities were increased in the perfusate, depending on the duration of ischemia at both 4 degrees C and 37 degrees C, the ratio of the latter to the former was significantly higher after 37 degrees C-ischemia than after 4 degrees C-ischemia. The stimulation stage of Kupffer cells evaluated in situ by formazan deposition after liver perfusion with nitro blue tetrazolium and phorbol myristate acetate was elevated after 4 degrees C-ischemia longer than 1 h, but not after 37 degrees C-ischemia. In contrast, the degree of oxidative stress in hepatocytes assessed by formazan deposition after liver perfusion with nitro blue tetrazolium alone was greater after 37 degrees C-ischemia than after 4 degrees C-ischemia. These results suggest that oxidative stress in hepatocytes and the stimulatory state of Kupffer cells after ischemia-reperfusion may differ between 4 degrees C-ischemia and 37 degrees C-ischemia, probably leading to different development of liver damage.

Alanine Transaminase↗