Potentials of enzyme tests and radioisotope hepatography in detecting early functional changes in the liver

The enzymic tests and radionuclide hepatography were used to study and compare liver function after rabbits were exposed to tetrachloromethane poisoning. The activity of serum enzymes of cholinesterase, alkaline phosphatase, aldolase and leucine aminopeptidase was determined. Hepatography was made with the use of 198Au-colloid with an activity 0.74 MBC. The enzymic tests were demonstrated to be more sensitive than radionuclide hepatography in detecting the earliest parenchymatous lesions in the liver. The data obtained correlate with the data of the pathohistological examinations, which demonstrated the presence of marked vacuole parenchymatous fatty dystrophy. The authors recommend that the enzymic tests should be used for detecting early hepatic lesions induced by tetrachloromethane.     

Effects of thyroxine on the synthesis of folate coenzymes in rat liver

1. The effects of thyroidectomy and of ;acute' and ;chronic' administration of thyroxine on the synthesis of folate coenzymes were studied by determining the liver contents of folate active derivatives and the enzymic activities involved in their biosynthesis. The effect of thyroxine on the same enzymes in vitro was also studied. 2. In thyroidectomized rats the liver contents of folate coenzymes did not change except for a slight decrease in the contents of 5-formyltetrahydrofolate and tetrahydrofolate compared with those in control rats. 3. In the same animals serine hydroxymethyltransferase and formyltetrahydrofolate synthetase activities decreased markedly. 4. The ;chronic' administration of thyroxine to thyroidectomized rats caused more evident variations in the liver contents of folate coenzymes and in particular a decrease in the contents of 5-formyltetrahydrofolate, tetrahydrofolate, 5(or 10)-formyl derivatives of tetrahydropteroylpolyglutamate and of 5(or 10)-formyl derivatives of pteroylpolyglutamate. 5. The enzymic activities did not show significant variations. 6. The ;acute' administration of thyroxine caused changes in the liver contents of some folate derivatives such as 10-formyldihydrofolate, 10-formylfolate, tetrahydrofolate and the 10-formyl derivative of dihydropteroylpolyglutamate. In these animals also the enzymic activities were unchanged. 7. No effect of thyroxine on enzymic activities in vitro was observed.     

Change in the cooperation of T- and B-lymphocytes during the immune response of ram erythrocytes in the presence of liver injury by carbon tetrachloride

Changes in cooperation of T- and B-lymphocytes induced by the immune response to the ram erythrocytes under conditions of liver injury by CCl4 in donors of cells or recipients have been studied on CBA line mice in the adaptive transfer system. It is stated that application of CCl4 induces changes in functional properties of T- and B-lymphocytes and process of their cooperation. The pattern of these changes is determined by periods passed after application of the hepatotropic poison, e. i. by the degree of the liver injury and by the stage of the pathological process in it. Application of CCl4 exerts more pronounced inhibiting effect on B-lymphocytes than on T-lymphocytes.     

Nicotinamide coenzyme levels and activity of enzymes of their biosynthesis and degradation in animal tissues after exposure to extreme conditions and pathogenic factors

Studies of enzymic systems of biosynthesis and decay of nicotinamide coenzymes under the effect of extremal and pathogenic factors have shown that the activation of enzymes of the nucleosidase cleavage of coenzymes is the most essential link in the mechanism of concentration disturbance of metabolically active vitamin PP forms under cooling and development of inflammatory processes in the myocardium and liver. Inhibition of the enzymic activity in the biosynthesis of coenzymes under allergic myocarditis and hepatitis may play a definite role in the mechanism of disturbance of the coenzymic function of vitamin PP.     

Protective effect of esculetin on hyperglycemia-mediated oxidative damage in the hepatic and renal tissues of experimental diabetic rats

Diabetes mellitus is the most common serious metabolic disorder and it is considered to be one of the five leading causes of death in the world. Hyperglycemia-mediated oxidative stress plays a crucial role in diabetic complications. Hence, this study was undertaken to evaluate the protective effect of esculetin on the plasma glucose, insulin levels, tissue antioxidant defense system and lipid peroxidative status in streptozotocin-induced diabetic rats. Diabetic rats exhibited increased blood glucose with significant decrease in plasma insulin levels. Extent of oxidative stress was assessed by the elevation in the levels of lipid peroxidation markers such as thiobarbituric acid reactive substances (TBARS), lipid hydroperoxides (HP) and conjugated dienes (CD); reduction in the enzymic antioxidant enzymes like superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase (GPx), glutathione-S-transferase (GST); nonenzymic antioxidants Vitamin C, E and reduced glutathione (GSH) were observed in the liver and kidney tissues of diabetic control rats as compared to control rats. Oral supplementation of esculetin to diabetic rats for 45 days significantly brought back lipid peroxidation markers, enzymic and nonenzymic antioxidants to near normalcy. Moreover, the histological observations evidenced that esculetin effectively rescues the hepatocytes and kidney from hyperglycemia mediated oxidative damage without affecting its cellular function and structural integrity. These findings suggest that esculetin (40 mg/kg BW) treatment exerts a protective effect in diabetes by attenuating hyperglycemia-mediated oxidative stress and antioxidant competence in hepatic and renal tissues. Further, detailed studies are in progress to elucidate the molecular mechanism by which esculetin elicits its modulatory effects in insulin signaling pathway.     

Influence of 2-mercaptopropionylglycine on DMBA-induced biochemical changes in regenerating mouse liver: I. Key enzymes of glycolysis and lactate dehydrogenase

When the chemical carcinogen, DMBA, is administered by intragastric intubation to young adult female mice already subjected to partial hepatectomy, the glycolytic key enzymes (hexokinases, phosphofructokinase, pyruvate kinase) and lactate dehydrogenase show declined levels in the regenerating liver. But concomitant administration of MPG, a hepatotropic detoxicant, with DMBA either nullifies or minimizes the effect of the carcinogen on these enzymes.     

Zinc-mediated thermal stabilization of carboxypeptidase A

In this study we investigated the contribution of Zn ions to the catalytic and structural thermostability of carboxypeptidase A (CPA). Structural studies on CPA molecule, performed in the presence of a number of ligands, demonstrated the multiple binding models around Zn ions which may affect the enzyme functions. Zinc was reported to bind at various sites in the CPA molecule at room temperature leading to inhibition of its enzymic activity. In this study we found that binding of Zn to CPA molecule followed by exposure to 50 degrees C did not inhibit the enzymic activity but activates and protects it against heat denaturation. The stabilization effect was found to be dependent on the increasing Zn/CPA ratios. The moderate changes of CPA activity as well as the UV and fluorescence spectra analyses indicate that the main function of the newly introduced zinc atoms is structural rather than catalytical.     

Methods for the study of liver cell heterogeneity

A large number of histological, histochemical and biochemical techniques are available for studying liver cell heterogeneity. Structural differences are recognized by morphometric analyses of electron micrographs. The zonal heterogeneity of enzyme activities can be demonstrated by histochemistry and more precisely by ultramicrobiochemical assays in microdissected periportal and perivenous tissue. Immunohistochemistry is useful for quantifying and localizing proteins, especially isoenzymes, without depending on their biological activity. The zonal quantification of specific mRNA can be achieved by in situ hybridization. The different structural and enzymic equipment of periportal and perivenous tissue found by these techniques has led to the concept of metabolic zonation. This hypothesis can be confirmed by determination of metabolic rates in perfused liver after selective zonal damage, in separated periportal and perivenous hepatocytes as well as in periportal and perivenous tissue of perfused liver by non-invasive techniques.     

The role of cholesteryl 14-methylhexadecanoate in peptide elongation reactions

1. Peptide-elongation factors were purified from rat liver and human tonsils and the contents of cholesteryl 14-methylhexadecanoate were determined in fractions obtained during enzyme purification. The relative contents of this compound in purified enzyme preparations was several times higher than that in the crude starting material. Elongation factors from human tonsils contained a significantly larger quantity of the cholesteryl ester than enzyme from rat liver. 2. Transfer enzymes extracted with various organic solvents showed variable decreased activities in both binding and peptidization assay. The decrease of enzymic activity was proportional to the amount of cholesteryl 14-methylhexadecanoate extracted from a given enzymic preparation. In systems containing both extracted elongation factors the polyphenylalanine synthesis was limited by the residual activity of the less active transfer factor. 3. The original enzymic activity of extracted transferases was fully recovered by the addition of pure cholesteryl 14-methylhexadecanoate in quantities corresponding to those extracted. 4. Increase of the relative contents of this cholesteryl ester during enzyme purification, decrease of the enzymic activity after the extraction and its recovery by the addition of this compound indicates that the presence of this ester in elongation factors is essential for the normal function of these enzymes.     

Dependence of nitrazepam metabolism on the method of its administration and species of experimental animals

Intraperitoneal, intravenous and peroral administration of nitrasepam has no effect on its transformation and distribution in the liver tissues, blood and brain of mice. Depending on the products of nitrasepam transformation formed in the animal liver, the enzymic systems providing such transformations have species peculiarities: the rat liver tissues contain nitroreductase, N-acetyl-transferase and desacetylase. And the mice tissues contain only nitroreductase and desacetylase.     

自噬在肝再生中的作用

自噬是存在于真核细胞内的一种溶酶体依赖性的降解途径,在肝脏生理和病理过程中发挥着重要作用。肝脏具有强大的再生能力,在受到急、慢性损伤时,残肝细胞将会被激活进入细胞周期进行细胞增殖,以补偿丢失的肝组织和恢复肝功能。文章阐述了各种类型损伤之后的肝再生与自噬的关系。在物理性、酒精、食源性等因素引起的肝损伤中,肝脏通过启动自噬来促进肝再生;在化学性损伤的肝再生模型中,自噬在其中的作用仍然有争议;在病毒感染之后的肝再生中,一些嗜肝病毒（如丙肝病毒和乙肝病毒等）反而利用自噬来促进病毒颗粒复制,抑制肝再生。对自噬和肝再生机制的研究,将有助于进一步阐明再生过程,为治疗肝脏疾病提供新方法。     

Use of enzymic preparations during diosgenine isolation from Dioscorea caucasica Lipsky]

The use of enzymic preparations of the cellulolytic and macerating effect was studied as applied to the isolation of diosgenine from rhizomes of Dioscorea caucasica Lypsky. The enzymic treatment of the steroid containing raw material prior to acid hydrolysis increased the yield of diosgenine by 30-48%. It is suggested that additional extraction of diosgenine takes place due to: 1) enzymic hydrolysis of structural polysaccharide components of the plant tissue and intercellular binding materials and 2) disintegration of glycoside bonds of saponins.     

Generation of a humanized mouse model with both human immune system and liver cells to model hepatitis C virus infection and liver immunopathogenesis

Establishing a small animal model that accurately recapitulates hepatotropic pathogens, including hepatitis C virus (HCV) infection and immunopathogenesis, is essential for the study of hepatitis virus-induced liver disease and for therapeutics development. This protocol describes our recently developed humanized mouse model for studying HCV and other hepatotropic infections, human immune response and hepatitis and liver fibrosis. The first 5-h stage is the isolation of human liver progenitor and hematopoietic stem cells from fetal liver. Next, AFC8 immunodeficient mice are transplanted with the isolated progenitor/stem cells. This generally takes 2 h. The transplanted mice are then treated for a month with the mouse liver apoptosis-inducing AFC8 dimerizer and left for an additional 2-month period to permit human liver and immune cell growth as well as system reconstitution and development before inoculation with HCV clinical isolates. HCV infection, human immune response and liver disease are observed with high incidence from approximately 2 months after inoculation.     

Alkaline phosphates from human milk. Comparison with isoenzymes from placenta and liver.

Alkaline phosphatase was partially purified from human milk and its antigenic, functional and structural properties were characterized. By immunochemical and enzymic criteria, the enzyme resembled the alkaline phosphatase isoenzyme found in human liver. Two-dimensional electrophoretic analysis showed that the milk enzyme differed from the liver both in subunit molecular weight and in isoelectric point. These differences were shown to result from variation in sialic acid content.     

Immunopathogenesis of hepatitis B virus infection

Hepatitis B virus (HBV) infection is a non-cytopathic hepatotropic virus that can lead to severe liver disease including acute hepatitis, cirrhosis and hepatocellular carcinoma. Successful clearance of the virus as well as the establishment of liver disease is largely driven by a complex interaction between the virus and the host immune response. In this review, the immunological events, including both the innate and adaptive immune response are discussed in the setting of both acute and chronic HBV infection and liver disease.     

Role of vitamin A in sulphate metabolism: Studies on the enzymic activation of sulphate by various tissue extracts of normal and vitamin A-deficient rats

1. The enzymic activation of sulphate by various tissue extracts of vitamin A-deficient rats and their pair-fed controls was studied. 2. Vitamin A deficiency does not impair the enzymic activity in liver, colon and brain. However, a significant decrease in activity was observed in epiphyseal cartilage.     

Effect of chronic CCl4 poisoning in the rat and of partial hepatectomy of the pathologically altered organ on glycogen levels of hepatocytes

A cytofluorometric study was made of total glycogen in rat liver cells in the norm and upon the chronic intoxication with CCl4. The liver cells were obtained from rats by means of intravital needle aspiration biopsy at the beginning of the experiment, after 3, and 6 months, and 1 month after partial hepatectomy of control and cirrhotic livers. Glycogen contents in liver cells were attributed to dry weight measured interferometrically. Upon the long-term chronic intoxication of rats with the hepatotropic poison the glycogen content increased by 1.4-2.5 times, and in some cells of cirrhotic livers even by 5-5.5 times compared to the normal level. 1 month after the resection both glycogen content and rat liver cell morphology were seen almost close to the normal. The data are discussed in terms of results earlier reported elsewhere on the increase of glycogen content in liver cells of patients with chronic hepatitis.     

Methylation of nuclear proteins by dimethylnitrosamine and by methionine in the rat in vivo

1. The incorporation of methyl groups into histones from dimethylnitrosamine and from methionine was studied by injection of the labelled compounds, isolation of rat liver and kidney histones, and analysis of hydrolysates by column chromatography. 2. Labelled methionine gave rise to labelled in-N-methyl-lysine, di-in-N-methyl-lysine and an amino acid presumed to be omega-N-methyl-arginine. 3. Administration of labelled dimethylnitrosamine gave rise to labelled S-methylcysteine, 1-methylhistidine, 3-methylhistidine and in-N-methyl-lysine derived from the alkylating metabolite of dimethylnitrosamine. In addition, labelled formaldehyde released by metabolism of dimethylnitrosamine leads to the formation of labelled S-adenosylmethionine, and hence to labelling of in-N-methyl-lysine, di-in-N-methyl-lysine and omega-N-methylarginine by enzymic methylation. 4. The formation of in-N-methyl-lysine by alkylation of liver histones was confirmed by using doubly labelled dimethylnitrosamine to discriminate between direct chemical alkylation and enzymic methylation via S-adenosylmethionine. These experiments also suggested the possibility that methionine residues in the histones were alkylated to give methylmethionine sulphonium residues. 5. The extent of alkylation of liver histones was maximal at about 5h after dosing and declined between 5 and 24h. The methylated amino acids resulting from direct chemical alkylation were preferentially lost: this is ascribed to necrosis of the more highly alkylated cells. 6. Liver histones were about four times as alkylated as kidney histones; the extent of alkylation of liver histones was similar to that of liver total nuclear proteins. 7. Methyl methanesulphonate (120mg/kg) alkylated liver histones to a greater extent than did dimethylnitrosamine. Diethylnitrosamine also alkylated liver histones. 8. The results are discussed with regard to the possible effects of alkylation on histone function, and the possible role of histone alkylation in carcinogenesis by the three compounds.     

Murine coronavirus-induced hepatitis: JHM genetic background eliminates A59 spike-determined hepatotropism

Recombinant murine coronaviruses, differing only in the spike gene and containing the strain A59 (moderately hepatotropic) and JHM (neurotropic) spike genes in the background of the JHM genome, were compared for the ability to replicate in the liver and induce hepatitis in weanling C57BL/6 mice. Interestingly, expression of the A59 spike glycoprotein within the background of the neurotropic JHM strain does not reproduce the A59 hepatotropic phenotype. Thus, the JHM genetic background plays a dominant role over the spike in the determination of hepatotropism.     

日本血吸虫性病兔肝纤维化的酶组织化学研究

目的观察日本血吸虫感染家兔导致肝脏发生纤维化后的肝组织酶学改变.方法将23只成年健康大耳白兔分为正常对照组(N)8只,模型组(M)15只,M组采用腹贴法(日本血吸虫尾蚴180条/只,持续15min)感染血吸虫,六周后服用吡喹酮行杀虫治疗.于实验的第13周将全部动物麻醉后剖腹取肝组织.肝组织行HE染色和电镜观察;酶组织化学方法检测单胺氧化酶(MAO)、一氧化氮合酶(NOS)、琥珀酰脱氢酶(SDH)、乳酸脱氢酶(LDH)在器官的表达活性.结果在血吸虫感染家兔的第13周可观察到肝组织明显纤维化;模型组中MAO、NOS、LDH活性明显高于正常对照组,而SDH活性则明显降低.结论慢性血吸虫感染引起的肝纤维化导致肝细胞缺血缺氧,影响NOS、SDH、LDH活性,加重肝细胞损伤.