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Biomedical subjects

M Imoto

Publications and source records attributed to M Imoto.

At least 109 records · Page 6Linked to original sources
PubMed1987

Characterization of histamine H1-receptor on rat hepatocytes.

The binding sites for [3H]pyrilamine in isolated rat hepatocytes were characterized. Scatchard analysis revealed two kinds of binding sites in hepatocytes, a high-affinity site and a low-affinity one. The rates of binding of the radioligand with the high-affinity binding site and its dissociation were rapid. The specificity of the sites for various histamine antagonists indicated that the high-affinity [3H]pyrilamine binding site is representative of the histamine H1 receptor. Treatment of hepatocytes with protease or phospholipase A2 significantly decreased the maximum binding capacity of the high-affinity site without affecting its dissociation constant, suggesting that the binding site is proteinaceous and is sensitive to a change in the lipid moiety of the membrane. Hepatocytic cyclic AMP and cyclic GMP were not significantly modulated by incubating hepatocytes with histamine. Thus, the action of histamine on hepatocytes might not be mediated by the cyclic nucleotides.

Animals↗
PubMed1987

Antitumor activity of erbstatin, a tyrosine protein kinase inhibitor.

A tyrosine protein kinase inhibitor, erbstatin, showed no antineoplastic effect on L-1210 mouse leukemia when it was injected alone. Erbstatin was found to be inactivated by incubation in serum, but not in dialyzed serum. It was also inactivated in reconstituted serum containing dialyzed serum components and ferric or ferrous ion. Because erbstatin was considered to be inactivated by the ferric or ferrous ion in serum, foroxymithine, which is a potent chelator for the ferric ion, was given to the mice together with erbstatin. Administration of both erbstatin and foroxymithine showed antineoplastic activity against L-1210 leukemia.

Animals↗
PubMed1987

In situ inhibition of tyrosine protein kinase by erbstatin.

Erbstatin inhibited the kinase activity of the receptor for epidermal growth factor in cultured A431 cells, while it did not alter turnover of the receptor protein. It also inhibited autophosphorylation of the src gene product p60src in Rous sarcoma virus-infected normal rat kidney cells. Erbstatin did not inhibit the binding of epidermal growth factor to its receptor but did inhibit internalization of epidermal growth factor-receptor complexes. It did not inhibit the epidermal growth factor-stimulated phosphatidylinositol turnover in A431 cells. Thus, erbstatin inhibited two oncogene product-related tyrosine protein kinases in situ and thus is a useful tool to study the role of tyrosine protein kinase.

Animals↗
PubMed1986

Clinical evaluation of serum 3 beta-hydroxy-5-cholenoic acid in hepatobiliary diseases.

Serum 3 beta-hydroxy-5-cholenoic acid (3 beta-OH-delta 5) was analyzed in 100 cases (90 patients with hepatobiliary diseases, 10 normal subjects) and its clinical significance investigated. The measurement of 3 beta-OH-delta 5 was performed by high performance liquid chromatography (HPLC) with immobilized 3 beta-hydroxysteroid dehydrogenase (3 beta-HSD) as the enzyme column. Esterified 3 beta-OH-delta 5 was measured after enzymatic hydrolysis with sulfatase and beta-glucuronidase. 3 beta-OH-delta 5 was hardly detected in normal cases. On the other hand, serum 3 beta-OH-delta 5 levels were remarkably high in cholestatic cases and also high in other cases with high bilirubin levels. The ratio of glycine- to taurine-conjugates (G/T ratio) was effective in discriminating cholestasis from hepatocellular damage such as in cases of acute hepatitis or fulminant hepatitis. More than 90% of the 3 beta-OH-delta 5, which is toxic, was sulfated or glucuronidated, suggesting detoxification by esterified bile acids. Significant increases of taurine-conjugated 3 beta-OH-delta 5 were observed in cases with pruritus, and a relationship between taurine-conjugated and pruritus was presumed. Therefore, analysis of 3 beta-OH-delta 5 is considered to be effective in clarifying the pathogenesis of hepatobiliary diseases.

3-Hydroxysteroid Dehydrogenases↗
PubMed1986

Synthetic Salmonella-type lipid A antigen with high serological specificity.

A synthetic compound (compound 516), beta(1-6)-linked D-glucosamine disaccharide 1,4'-bisphosphate, which is acylated by (R)-3-hexadecanoyloxytetradecanoyl, (R)-3-hydroxytetradecanoyl, (R)-3-dodecanoyloxytetradecanoyl, and (R)-3-tetradecanoyloxytetradecanoyl groups at positions 2,3,2', and 3', respectively, exhibited in vitro antigenic reactivity of high specificity comparable to that of free lipid A from Salmonella minnesota R595. This was confirmed by an enzyme-linked immunosorbent assay and an enzyme-linked immunosorbent assay inhibition test with monoclonal and conventional antibodies. The results of comparative analysis performed with several synthetic lipid A analogs as well as three monosaccharide derivatives suggested that the complete structure involving both phosphate groups at the C-1 and C-4' positions and the 3-acyloxyacyl groups at the C-2, C-2', and C-3' positions of the glucosamine disaccharide are required for the expression of the serological specificity of Salmonella-type lipid A. This was deduced from the observations that compound 506, a synthetic Escherichia coli-type lipid A which has the same structure as that of compound 516, except that 3-hydroxytetradecanoyl group is substituted for an acyloxyacyl residue at the C-2 position, exhibited significantly reduced antigenic reactivity as compared with compound 516 and that the replacement by the hydrogen atom of the phosphoryl group at the C-1 position or by 3-hydroxytetradecanoyl or tetradecanoyl groups of acyl residues at the 2, 3, 2', and 3' positions of compound 516 results in a marked reduction of reactivity with monoclonal antibodies 5G and 36G. Similar results were obtained by assays with conventional rabbit antibodies, but the structural difference between compounds 516 and 506 could not be distinguished by these polyclonal antibodies. The results of cross-reactions among synthetic analogs with monoclonal antibodies 161M and 1-9M, which have been confirmed to exhibit different serological specificities from the 5G or 36G antibody, also suggested that the nature and linkage of fatty acyl residues as well as the backbone structure of lipid A play an important role in determining serological specificity of the lipid A molecule.

Antigens, Bacterial↗
PubMed1986

Immunohistochemical studies on structural changes of the hepatic lobules in chronic liver diseases.

Liver biopsy specimens were examined immunohistochemically to clarify structural changes of the hepatic lobules in chronic liver diseases. In normal liver carbohydrate antigen 19-9 was located in the biliary ductular epithelium, whereas factor VIII-related antigen was observed in the endothelium of portal veins, hepatic arteries, and central veins. This antigen was not detected in the sinusoidal endothelium. In contrasts, monoclonal antibody OKM5 was reactive with the sinusoidal endothelium but was unreactive with the endothelium of the portal blood vessels or central veins. In chronic active hepatitis and liver cirrhosis, both carbohydrate antigen 19-9 positive biliary ductular cells and factor VIII-related antigen positive endothelial cells were not only observed in the enlarged portal area but also extended into the parenchyma. They were occasionally accompanied by fibers. These findings suggest that fibrosis, ductular epithelial, and blood vascular proliferation in the portal space and their invasion into the parenchyma might gradually cause structural changes of the hepatic lobules in chronic liver disease.

Antigens↗
PubMed1985

Synthetic and natural Escherichia coli free lipid A express identical endotoxic activities.

The recently chemically synthesized Escherichia coli lipid A and the natural free lipid A of E. coli were compared with respect to their endotoxic activities in the following test systems: lethal toxicity, pyrogenicity, local Shwartzman reactivity, Limulus amoebocyte lysate gelation capacity, tumour necrotizing activity, B cell mitogenicity, induction of prostaglandin synthesis in macrophages, and antigenic specificity. It was found that synthetic and natural free lipid A exhibit identical activities and are indistinguishable in all tests.

Animals↗
PubMed1985

Predominance of histamine H1 receptors on liver plasma membrane.

We quantitatively determined the receptors for histamine H1, histamine H2, alpha- and beta-adrenergic, prostaglandin E2 and F2 alpha in liver plasma membranes. The number of the receptors was the greatest in histamine H1 receptors (4740 +/- 750 fmol/mg protein) and the second in alpha-adrenergic receptors (965 +/- 16). Although relatively small numbers of the receptors were observed for histamine H2 (116 +/- 11) and prostaglandin E2 (38.0 +/- 8.9), we could not determine the number and affinity of beta-adrenergic and prostaglandin F2 alpha receptors. In contrast to the number of receptors, there was not significant difference in the affinities of receptors for histamine H1, histamine H2, alpha-adrenergic hormone and prostaglandin E2. These results suggest that histamine and its receptor play some role in liver function.

Animals↗
PubMed1985

Saquayamycins, new aquayamycin-group antibiotics.

From the culture broth of Streptomyces nodosus MH190-16F3, four new antibiotics have been isolated, and named saquayamycins A, B, C and D. The compounds are glycosides of aquayamycin, and among aquayamycin-group antibiotics they are most closely related to P-1894B (vineomycin A1). All saquayamycins act on Gram-positive bacteria and inhibit the growth of adriamycin-sensitive and adriamycin-resistant P388 leukemia cells.

Animals↗
PubMed1985

Immunohistochemical detection of alpha-fetoprotein, carcinoembryonic antigen, and ferritin in formalin-paraffin sections from hepatocellular carcinoma.

Paraffin sections of livers from 20 patients with hepatocellular carcinoma were examined by a method using peroxidase antiperoxidase for the detection of alpha-fetoprotein, carcinoembryonic antigen, and ferritin. Ferritin was detected in 70% of the cases, alpha-fetoprotein was in 50% and carcinoembryonic antigen in 30%. The incidence of the detection of these antigens was in accordance with the incidence of these antigens in the sera of patients with hepatocellular carcinoma. Moreover, these antigens were mainly expressed in the well differentiated type of hepatocellular carcinoma by the Edmondson's criteria. Our results also revealed that different antigens were usually present in different tumor cells, although some cells displayed two or more antigens simultaneously. These findings suggest that hepatocellular carcinoma cells are functionally heterogeneous, even if they appear histologically monomorphic.

Aged↗
PubMed1985

Serum levels of secretory immunoglobulin A in liver disease.

Secretory immunoglobulin A (sIgA) in serum was measured in patients with various liver diseases using enzyme immunoassay specific to sIgA. Marked elevation of the serum sIgA concentrations was found in liver diseases especially in intrahepatic or extrahepatic cholestasis. In chronic hepatitis and liver cirrhosis serum sIgA correlated significantly with leucine aminopeptidase (r = 0.69), GOT (r = 0.66), alkaline phosphatase (r = 0.55), and direct bilirubin (r = 0.42). In acute hepatitis their levels correlated significantly with total bilirubin (r = 0.59) and GPT (r = 0.55). In acute hepatitis and acute exacerbation of chronic hepatitis the major peaks of serum sIgA were observed later than those of liver enzymes. These results suggest two mechanisms working to elevate the serum sIgA levels in liver diseases. In chronic hepatitis, liver cirrhosis, and intrahepatic and extrahepatic cholestasis the raised serum sIgA probably reflects reflux of bile, a rich source of secretory component and sIgA, into circulation. In acute or chronic massive liver necrosis elevation of sIgA may be associated with liver regeneration. Serial measurement of serum sIgA with other conventional parameters will contribute much to the understanding of the pathophysiology of liver diseases.

Acute Disease↗
PubMed1985

Mechanism of liver mitochondrial dysfunction associated with bile duct obstruction.

To elucidate the mechanism of liver mitochondrial dysfunction induced by obstructive jaundice, the following experiments were performed. In vivo study: Using Wistar male rats, bile ducts were ligated, and serum levels of total bilirubin (T-Bil), GOT, GPT, mitochondrial GOT (mGOT) and total bile acids (TBA) were measured at 3 and 7 days after the ligation. Then, the liver was isolated to determine mitochondrial functions and to measure the content of fatty acids in mitochondrial phospholipids by high performance liquid chromatography. The levels of T-Bil, GOT, GPT, mGOT and TBA were elevated by the bile duct ligation. Mitochondrial functions were deteriorated, and contents of arachidonic acid, palmitic acid and stearic acid in mitochondrial phospholipids decreased. Pretreatment with coenzyme Q10 (E-0216, CoQ10), an antidetergent agent, prevented not only the development of mitochondrial dysfunction and the decrease in mitochondrial phospholipids but also the elevation of GOT, GPT, and mGOT although CoQ10 did not prevent the elevation of T-Bil and TBA levels. In vitro study: Using intact rat liver mitochondria, the effect of taurocholic acid (TCA), one of the physiological bile salts, on the mitochondrial function and on mitochondrial phospholipids was examined. Incubation of mitochondria with TCA induced a dose-dependent deterioration of mitochondrial function and the increase in the content of solubilized phospholipids. The protective effect of CoQ10 was also observed in the in vitro study. These results indicate that degradation of mitochondrial phospholipids by bile acids is responsible for the early phase of liver dysfunction induced by obstructive jaundice.

Alanine Transaminase↗
PubMed1984

Biological activities of analogues of lipid A based chemically on the revised structural model. Comparison of mediator-inducing, immunomodulating and endotoxic activities.

Lipid A analogues were chemically synthesized based on the model structure recently revised, and biological activities of the analogues were tested. The analogue, (beta-1,6)-linked glucosamine disaccharide carrying ester-bound 3-hydroxytetradecanoic acids at 3 and 3' position of reducing and nonreducing glucosamine in addition to amide-bound 3-hydroxytetradecanoic acids and glycosidic-linked and ester-linked phosphate groups, showed much stronger activities for mediator inducing and immunomodulating as well as endotoxic activities than those exhibited by the previously synthesized analogues based on the old model. Among the activities tested, induction of interferon and tumor necrosis factor as well as mitogenicity, adjuvanticity and pyrogenicity were, however, not expressed so strongly as natural lipid A used as controls. In contrast, the analogue exhibited comparable activities to those of control lipid A in the test of lethal toxicity to mice and gelating activity of Limulus amebocyte lysate. Other synthetic analogues carrying a phosphate group showed comparable, slightly stronger or weaker activities depending on the test, but nonphosphorylated analogue exhibited no apparent or only very weak activities.

Adjuvants, Immunologic↗