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Biomedical subjects

S Nagoshi

Publications and source records attributed to S Nagoshi.

At least 19 recordsLinked to original sources
PubMed2000

Increased expression of osteopontin in activated Kupffer cells and hepatic macrophages during macrophage migration in Propionibacterium acnes-treated rat liver.

Osteopontin is an extracellular matrix component that can act as a chemokine to induce macrophage migration. The significance of osteopontin in macrophage infiltration into the liver was examined in rats given heat-killed Propionibacterium acnes. In normal rats, osteopontin mRNA expression in the liver was minimal, determined by quantitative-competitive reverse transcription-polymerase chain reaction (RT-PCR) assay. Northern blot analysis revealed that osteopontin mRNA was not expressed in Kupffer cells isolated from normal rats. When rats received heat-killed P. acnes intravenously, marked macrophage accumulation, forming granulomas, developed in the liver later than 3 days after the injection and its extent became maximal between 5 and 7 days. In these rats, osteopontin mRNA expression was increased in the liver later than 1 day (with its peak at 3 days after the injection), and the mRNA expression was increased markedly in Kupffer cells and hepatic macrophages isolated at 7 days. The mRNA expression of monocyte chemotactic protein-1 (MCP-1) and macrophage inflammatory protein-1alpha (MIP-1alpha), chemokines for monocytes and macrophages, was also increased in the liver of P. acnes-treated rats, with peak expression at 3 days. We conclude that osteopontin derived from Kupffer cells and hepatic macrophages may contribute to the infiltration of monocytes and macrophages into the liver cooperatively with the actions of MCP-1 and MIP-1alpha in P. acnes-treated rats.

Animals↗
PubMed1999

Inhibition of hepatic stellate cell contraction during activation in vitro by vascular endothelial growth factor in association with upregulation of FLT tyrosine kinase receptor family, FLT-1.

Activated hepatic stellate cells produce vascular endothelial growth factor (VEGF). VEGF has been shown to act on mesenchymal cells as well. If hepatic stellate cells can express FLT tyrosine receptor family, flt-1 and KDR/flk-1, their function might be regulated by VEGF in an autocrine manner. This hypothesis was tested using hepatic stellate cells isolated from normal rats. Northern blot analysis and immunocytochemical study revealed that hepatic stellate cells cultured for 3 days on plastic dishes expressed both flt-1 and KDR/flk-1. When the culture was prolonged to 10 days, the flt-1 mRNA expression was increased, whereas both KDR/flk-1 mRNA and protein expressions diminished. DNA and collagen syntheses were minimal in the cells cultured for 3 days, but marked in those cultured for 10 days. Addition of recombinant human VEGF to the culture medium did not change both syntheses but attenuated an increase of smooth muscle alpha-actin expression in the cells during culture on plastic dishes and also contraction of collagen gels on which the cells were cultured. We conclude that VEGF may inhibit contraction of hepatic stellate cells appearing during activation by culture, probably through attenuation of smooth muscle alpha-actin expression via upregulated VEGF receptor, flt-1.

Animals↗
PubMed1999

Expression of osteopontin in Kupffer cells and hepatic macrophages and Stellate cells in rat liver after carbon tetrachloride intoxication: a possible factor for macrophage migration into hepatic necrotic areas.

Activated Kupffer cells and macrophages accumulate in necrotic areas in the liver. Osteopontin, an extracellular matrix with RGD sequence, has been shown to act as a chemokine that can induce monocyte migration. The possibility that osteopontin can play a role in infiltration of both cells into hepatic necrotic areas was investigated in rats. Northern blot analysis revealed that osteopontin mRNA expression was minimal in Kupffer cells and hepatocytes immediately after isolation from normal rats, but slight in hepatic stellate cells assumed nearly quiescent in function after 3 days of culture on plastic dishes. When rat received carbon tetrachloride, liver necrosis developed between 1 and 3 days following the intoxication. In these rats, osteopontin mRNA expression assessed by quantitative competitive RT-PCR was increased in the liver later than 1 day with its peak at 2 days following the intoxication. Kupffer cells and hepatic macrophages and hepatic stellate cells isolated from such liver showed marked expression of osteopontin mRNA on Northern blotting. Immunohistochemical examination disclosed that osteopontin was stained in macrophages including Kupffer cells and stellate cells in the necrotic areas. On electron microscopy, osteopontin stains were present in the Golgi apparatus in these cells. Recombinant human osteopontin promoted migration of Kupffer cells isolated from normal rats and cultured in a Transwell cell culture chamber in a dose-related manner. We conclude that activated Kupffer cells and hepatic macrophages and stellate cells express osteopontin. These cells might contribute to the infiltration of Kupffer cells and macrophages into hepatic necrotic areas by expressing osteopontin.

Animals↗
PubMed1998

Activated rat stellate cells express c-met and respond to hepatocyte growth factor to enhance transforming growth factor beta1 expression and DNA synthesis.

Hepatocyte growth factor (HGF) decreases transforming growth factor beta1 (TGFbeta1) levels in the liver and attenuates hepatic fibrosis caused by dimethylnitrosamine in rats. In the liver, HGF is presumed to act predominantly on parenchymal cells, and TGFbeta1 is produced mainly by mesenchymal cells. In hepatic fibrosis, stellate cells play a central role with undergoing activation, which also occurs when the cells are cultured on plastic. Thus, we wondered if HGF could act directly on stellate cells. c-Met was detected in rat stellate cells activated by culture for 10 days, but not in the cells cultured for 3 days. Specific binding of HGF to the activated cells was determined, and Scatchard analysis indicated an apparent Kd of 1.5 nM. c-Met mRNA was detected in freshly isolated stellate cells from rats treated with carbon tetrachloride for 8 weeks, but not in those cells from normal rats. These results indicate that stellate cells express c-met when activated in vitro and in vivo. HGF enhanced TGFbeta1 production and DNA synthesis in the activated cells.

Animals↗
PubMed1998

Hepatocyte apoptosis and hepatic expression of transforming growth factor-beta1 mRNA during involution of hyperplastic rat liver induced by hepatocyte growth factor.

Hepatocyte apoptosis occurs during involution of hyperplastic liver induced by administration of xenobiotic compounds in rats. With this hyperplasia and involution, hepatic transforming growth factor (TGF)-beta1 is reported to be expressed to stimulate hepatocyte apoptosis. In regenerating liver after partial resection showing no hyperplasia, such expression of TGF-beta1 is also seen. However, no hepatocyte apoptosis develops despite the high levels of TGF-beta1. When rats received an intravenous injection of human hepatocyte growth factor at 12 h intervals for 14 days, the hepatic DNA content was increased 12 h after the last injection to 140% of control. This DNA content was significantly decreased at 108 and 180 h after discontinuation of treatment. At 60 h after the last injection, the number of apoptotic bodies positive for nick end-labelling of DNA in hepatocytes was significantly greater in treated rats than in control rats. Hepatocyte apoptosis was also identified electron micrographically. Hepatic TGF-beta1 mRNA levels in treated rats were significantly lower than in control rats at 12 h and then gradually increased towards control levels. We conclude that hyperplastic liver induced in normal rats by hepatocyte growth factor regresses with hepatocyte apoptosis and suppressed hepatic TGF-beta1 mRNA levels.

Animals↗
PubMed1998

Enhancement of albumin production by hepatocyte growth factor in rat hepatocytes: distinction in mode of action from stimulation of DNA synthesis.

Hepatocyte growth factor (HGF) has been shown to enhance albumin production as well as stimulate DNA synthesis in hepatocytes. The mode of action of HGF in exerting both effects is to be elucidated. We previously observed that hepatocyte proliferation occurred in normal rats given recombinant human HGF (rhHGF) intravenously. When rats received rhHGF similarly, serum albumin levels were significantly increased compared to controls. In primary culture of rat hepatocytes, albumin concentration in culture medium was significantly increased by rhHGF added at 24 h of culture compared to controls, increasing with time of culture. This effect of rhHGF was dose-related. When actinomycin D was added to the medium, the albumin concentration was reduced in a dose-related manner, but its enhancement by rhHGF was maintained. Albumin mRNA levels were not increased by rhHGF. When rhHGF was added similarly to the medium, immunocytochemically positive hepatocytes for 5-bromo-2'-deoxyuridine (BrdU) incorporation appeared 30 h later. Of these labeled hepatocytes, 12.5% were concomitantly stained for albumin. In contrast, albumin-positive hepatocytes were seen in 77% of BrdU-non-labeled hepatocytes (p<0.01). We conclude that HGF may enhance albumin production through post-transcriptional regulation in non-proliferating hepatocytes, but not in proliferating hepatocytes.

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

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↗
PubMed1994

Protective action of putrescine against rat liver injury.

The hepatoprotective action of orally dosed putrescine was investigated using rat models of liver injury. When rats received putrescine orally soon after a dose of carbon tetrachloride or D-galactosamine, deranged serum alanine aminotransferase values and prothrombin times were significantly attenuated compared with control levels, with improved histologic extent of liver injury. Putrescine addition to the medium of rat hepatocytes in primary culture reduced cell killing induced by D-galactosamine or the membrane detergents chenodeoxycholic acid and Triton X-100. Similar reduction was seen in cells exposed to tert-butyl hydroperoxide (TBHP), an agent producing cell death through lipid peroxidation, with attenuation of cellular malondialdehyde content. Putrescine also significantly attenuated the extent of increased plasma membrane microviscosity as assessed with 1-[4-(trimethylammonio)phenyl]-6-phenyl-1,3,5-hexatriene in TBHP-treated cells. These results suggest that orally given putrescine protects against liver injury. Plasma membrane stabilization and reduction of lipid peroxidation may contribute to this hepatoprotection.

Administration, Oral↗
PubMed1994

Putrescine as a comitogen of epidermal growth factor in rat liver growth.

Putrescine can stimulate regeneration of the remnant liver after partial hepatectomy in rats when exogenously administered, but its mitogenic action has not been shown in cultured hepatocytes. To find its action site(s) in the regulation of hepatocyte proliferation, we examined its effect on hepatocyte DNA synthesis in relation to mitogenic action of epidermal growth factor in vitro and in vivo. When putrescine was added to the medium of adult rat hepatocytes in primary culture 36 hr after plating, DNA synthesis at 50 hr induced by addition of epidermal growth factor at 24 hr was significantly enhanced. This enhancement disappeared by removal of epidermal growth factor at the time of putrescine addition. Putrescine added to the medium was taken up in a dose-related manner by hepatocytes, irrespective of the presence of epidermal growth factor, whereas 125I-epidermal growth factor binding to hepatocytes was not affected by addition of putrescine. When rats received epidermal growth factor at 2-hr intervals until 10 hr, 5-bromo-2'-deoxyuridine labeled and mitotic hepatocytes were increased in number at 48 hr with increased hepatic DNA content. These increases were not affected by concomitant administration of putrescine until 10 hr, but significantly enhanced by additional administration of putrescine and epidermal growth factor from 20 to 30 hr. We conclude that putrescine may stimulate proliferation of hepatocytes that have entered the G1-phase of the cell cycle as a comitogen of epidermal growth factor, probably through action at the molecular levels to enhance its mitogenic activity.

Animals↗
PubMed1993

Stimulation of liver growth by exogenous human hepatocyte growth factor in normal and partially hepatectomized rats.

Human hepatocyte growth factor stimulates DNA synthesis by cultured rat hepatocytes. When human hepatocyte growth factor prepared from the culture medium of human embryonic lung fibroblasts was intravenously injected into normal rats and rats after 70% hepatectomy, it was detected in hepatocytes but not in nonparenchymal cells isolated 30 min after injection. Similar injections of human hepatocyte growth factor at 2-hr intervals for 10 hr significantly increased hepatic DNA content in normal rats at 48 hr, with increased hepatic content of putrescine, the essential polyamine for hepatic DNA synthesis after 70% hepatectomy, and activities of catalytic enzymes of putrescine synthesis at 6 hr almost to the levels in rats after 70% hepatectomy. Those levels in rats after 70% hepatectomy were further enhanced by similar injections of human hepatocyte growth factor starting immediately after surgery. Increased hepatic DNA content in normal rats and rats after 70% hepatectomy was also seen with recombinant human hepatocyte growth factor to a greater extent compared with that seen with human hepatocyte growth factor. In normal rats given recombinant human hepatocyte growth factor, 5-bromo-2'-deoxyuridine-labeled and mitotic hepatocytes were significantly increased in number at 26 hr but not at 48 hr. We conclude that exogenous human hepatocyte growth factor acts as a trigger and a promoter of liver growth to increase hepatic putrescine production in rats. Recombinant human hepatocyte growth factor is more potent than human hepatocyte growth factor in this action.

Animals↗
PubMed1992

Significance of serum human hepatocyte growth factor levels in patients with hepatic failure.

Serum human hepatocyte growth factor levels were measured using a newly developed enzyme-linked immunosorbent assay kit in patients with liver diseases. Serum human hepatocyte growth factor levels were increased in correlation with derangements of prothrombin time, total bilirubin and other parameters reflecting hepatocellular dysfunction in 112 patients with chronic liver disease. The levels were positively correlated with serum AST and ALT levels in 59 of these patients whose prothrombin times were within the normal range. Abnormally increased serum human hepatocyte growth factor levels were found in 100% of the determinations in 16 patients with fulminant hepatic failure and in 80% of the determinations in 16 patients with chronic hepatic failure. The levels greater than 1 ng/ml, however, were found in 94% of determinations in the former group, but only in 16% of the determinations in the latter group. This difference was seen irrespective of prothrombin time or hepatic coma grades. In patients with fulminant hepatic failure serum human hepatocyte growth factor levels were increased immediately after plasma exchange using heparin as the anticoagulant in 71% of the determinations. This increase disappeared 12 hr after discontinuation of plasma exchange. In 17 of 39 patients with chronic renal failure who had no liver disease, serum human hepatocyte growth factor levels were abnormally increased before hemodialysis using heparin, and the levels were elevated immediately after hemodialysis in all the patients. The increase of serum human hepatocyte growth factor levels in hepatic failure may be the result of hepatocellular dysfunction and necrosis.(ABSTRACT TRUNCATED AT 250 WORDS)

Chronic Disease↗
PubMed1992

Hepatocyte membrane stabilization by prostaglandins E1 and E2: favorable effects on rat liver injury.

When prostaglandin (PG) E1 was continuously administered to rats from 24 hours before giving a dose of carbon tetrachloride, deranged serum glutamic pyruvic transaminase levels and prothrombin time were significantly reduced 12 hours after intoxication compared with controls. A similar effect of PGE1 was seen at 24 hours in D-galactosamine-intoxicated rats. Liver histology showed a comparable attenuation of injury in these rats. These results were consistent with reported effects of PGE2, suggesting that both prostaglandins may share a common pathway in protection against liver injury. When PGE1 or 16,16'-dimethyl PGE2 was added to the medium of primary cultured rat hepatocytes, lipid peroxidation-dependent killing of the cells by tert-butyl hydroperoxide was significantly attenuated without affecting the extent of malondialdehyde accumulation compared with controls. Both prostaglandins significantly reduced the extent of increased plasma membrane microviscosity of these cells assessed by 1-[4-(trimethyl-ammonio)phenyl]-6-phenyl-1,3,5-hexatriene. PGE1 and PGE2 may possess cytoprotective effects on liver parenchymal cells through stabilization of membrane microviscosity, which may contribute to protection against liver injury.

16,16-Dimethylprostaglandin E2↗
PubMed1991

Stimulation of putrescine production by epidermal growth factor in rat liver after partial hepatectomy.

When epidermal growth factor was given to rats after partial hepatectomy, hepatic putrescine content was significantly increased at 4, 6 and 10 hr compared with control rats. Ornithine decarboxylase activity was also increased. Hepatic ornithine decarboxylase messenger RNA content was significantly greater than control levels at 2 hr after epidermal growth factor treatment, but not at 10 hr, when the amount of ornithine decarboxylase messenger RNA in control animals was four times that at 2 hr. When actinomycin D was administered 6 hr after partial hepatectomy, hepatic ornithine decarboxylase activity at 10 hr was reduced to half the control levels. This reduction was attenuated by epidermal growth factor treatment at 6 and 8 hr. Hepatic immunoreactive ornithine decarboxylase protein content showed a highly positive correlation with hepatic ornithine decarboxylase activity at 4, 6 and 10 hr, irrespective of epidermal growth factor treatment. Hepatic spermidine N1-acetyltransferase activity was significantly increased at 6 hr compared with control rats. These results suggest that, after partial hepatectomy in rats, exogenous epidermal growth factor may stimulate hepatic putrescine production by increasing ornithine decarboxylase messenger RNA content and altering posttranscriptional ornithine decarboxylase regulation, as well as enhancing spermidine N1-acetyltransferase activity.

Acetyltransferases↗
PubMed1991

Insulin and glucagon therapy of acute hepatic failure.

When insulin and glucagon are administered to rats with severe liver injury, survival is enhanced with an attenuation of the liver injury compared to that of untreated controls. In rats with acute liver injury both hormones produce a rapid normalization of hepatic protein content following initiation of DNA synthesis. When rats receive both hormones after partial hepatectomy, the first burst of DNA synthesis reaches a maximum earlier than that seen in controls. Both hormones enhance the increment of hepatic putrescine essential for DNA synthesis through activation of ornithine decaroxylase and/or spermidine-N1-acetyltransferase. The enhancement of putrescine content by each hormone is additive. Putrescine supplementation promotes hepatic DNA synthesis after hepatectomy. Based on these data, we conclude that a combination of insulin and glucagon is effective in the therapy of acute hepatic failure in rats. The restoration of liver function as well as the stimulation of liver cell proliferation via putrescine production may contribute to this effect.

Acetyltransferases↗
PubMed1991

Ornithine decarboxylase induction in partially hepatectomized rat liver and modes of its stimulation by glucagon and insulin.

Hepatic ornithine decarboxylase (ODC) activity increases after partial hepatectomy and this activity is further stimulated by pharmacologic doses of glucagon and insulin. We now present data suggesting that glucagon and insulin stimulate ODC activity by distinct mechanisms. ODC activity increased progressively after partial hepatectomy and reached an initial peak at 4 h. Activity decreased to 50% of its peak value at 6 and 8 h and then rose progressively to a maximum at 12 h. Enzymatic activity was well correlated with the amount of hepatic immunoreactive ODC protein, thus suggesting that increased enzyme activity was due to increased amount of enzyme protein. Hepatic ODC mRNA increased gradually and continuously, reaching the maximal value by 12 h. In rats receiving glucagon after partial hepatectomy, ODC mRNA increased significantly by 2 h and enzyme immunoreactive protein and activity by 2 to 4 h as compared to controls. In contrast, insulin administration only induced a significant increase in enzyme immunoreactive protein and activity 10 to 12 h after partial hepatectomy. No significant changes in ODC mRNA level were observed. Our data suggest that the regulation mechanism of ODC induction following partial hepatectomy differs depending on the time after operation. Our data also suggest that while glucagon appears to regulate ODC activity by a transcriptional mechanism, insulin appears to operate at a post-transcriptional level.

Animals↗
PubMed1991

Usefulness of pulsed Doppler ultrasound in detection of angiographically evident recurrence of hepatocellular carcinoma after arterial embolization treatment.

Because hepatocellular carcinoma treated by transcatheter arterial embolization often regains its size, routine follow-up is necessary. The usefulness of pulsed Doppler ultrasound for detection of this type of recurrence was compared with ultrasonography and computed tomography in 21 such hepatocellular carcinomas. Of 15 hepatocellular carcinomas diagnosed by angiography as showing recurrence, four were detected with ultrasonography and five were detected with computed tomography. Doppler signals were obtained in the peripheral portions corresponding to tumor vessels or stains on angiograms in 14 of these 15 hepatocellular carcinomas, but they were undetectable in six hepatocellular carcinomas with no recurrence. All signals disappeared after transcatheter arterial embolization. One false-negative hepatocellular carcinoma with pulsed Doppler ultrasound showed faint tumor stains on angiograms; these were also negative on ultrasonography and computed tomography. Pulsed Doppler ultrasound may be superior to ultrasonography and computed tomography as a routine procedure to detect the recurrence of hepatocellular carcinoma treated by transcatheter arterial embolization.

Aged↗