Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound   Target Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound

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Query: EC:3.4.15.1 (ACE)
18,300 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Autoantibodies are important diagnostic markers for autoimmune type chronic active hepatitis (AI-CAH) and primary biliary cirrhosis (PBC). At least three subgroups of AI-CAH can be distinguished serologically. Antinuclear antibodies (ANA), smooth muscle antibodies (SMA), and liver membrane autoantibodies (LMA) characterize classical autoimmune type 'lupoid' hepatitis, while liver kidney microsomal (LKM) antibodies identify a second, and antibodies to a soluble liver antigen (anti-SLA), a third subgroup of AI-CAH. Patients with autoimmune type CAH in contrast to patients with virus-induced liver diseases profit from immunosuppressive therapy. PBC is characterized by disease-specific subtypes of antimitochondrial antibodies (AMA). Technical developments, like immunoblotting and molecular cloning, led to a better definition and characterization of autoantibody-antigen systems. Molecular cloning has been successfully applied to identify the main 70 kDa mitochondrial antigen in PBC. This and other mitochondrial autoantigens have been identified as enzymes: E2 component of pyruvate dehydrogenase (PDH-E2) and its component X, branched chain alpha-keto acid dehydrogenase (BCKD-E2), and 2-oxoglutarate dehydrogenase. LKM-1 antigen has been identified as cytochrome P-450 db1, a drug metabolizing enzyme with a known genetic polymorphism. These cloned hepatic autoantigens share some characteristics with other autoantigens: they are enzymes, autoantibodies react with active sites of these enzymes and the autoepitopes are highly conserved. After the identification of these autoepitopes, specific and sensitive diagnostic reagents will become available. B and T cell epitope mapping will help to elucidate whether these autoantibodies are just clinically valuable diagnostic markers or whether they contribute to the immunopathogenesis or help to identify the aetiological agents.
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PMID:Autoantibodies and antigens in liver diseases--updated. 268 96

In a chronic study by the National Toxicology Program (NTP), dimethyl hydrogen phosphite (DMHP) caused neoplastic and nonneoplastic changes in the lungs and forestomach of F344/N rats following gavage administration for 2 years. The current investigation was designed to study the effect of a short-term exposure on a series of biochemical systems in target and nontarget tissues which may be involved in the metabolism and/or the manifestation of DMHP toxicity. Rats were treated daily with a dose similar to that used in the NTP study (200 mg/kg) for 4, 5, or 6 weeks. Two groups of animals were also treated for 4 weeks and then treatment was discontinued and the rats were allowed to recover for 1 or 2 weeks. An equal number of animals was treated similarly with the vehicle and used as control. The microsomal and soluble fractions were separated from liver, lungs, kidneys, forestomach, and glandular stomach from the 6-week treatment group. Another group of rats treated for 6 weeks was prepared for pathology examination of the lungs, forestomach, and glandular stomach. There was a significant increase in the weight of the forestomach of rats treated for 4, 5, or 6 weeks relative to control animals, while no significant difference was observed in the weight of liver, lungs, kidneys, and glandular stomach. The forestomach weight of rats treated for 4 weeks returned to the control value after 1 week of recovery. Microscopic examination of the forestomach of rats treated for 6 weeks revealed a thickened stratified squamous epithelium characterized by hyperplasia, hyperkeratosis, and subepithelial inflammation and edema. There were no microscopic changes in the lungs or glandular stomach of animals treated for 6 weeks. The activity of angiotensin converting enzyme in the serum of rats treated for 4, 5, or 6 weeks was significantly increased over that of control animals. The activity of this enzyme returned to near levels seen in the control animals after 1 week of recovery following 4 weeks of treatment. No treatment-related effect was observed in the activities of the microsomal p-nitroanisole demethylase, soluble glutathione S-transferase, and soluble superoxide dismutase in the five tissues studied. There was a significant increase in the level of nonprotein soluble sulfhydryls in the forestomach but in no other tissue of rats treated for 6 weeks. Also the activity of soluble carboxylesterase was significantly reduced in the lungs and forestomach, but not in any other tissue of the 6-week-treated rats.(ABSTRACT TRUNCATED AT 400 WORDS)
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PMID:Pathological and biochemical effects of dimethyl hydrogen phosphite in Fischer 344 rats. 283 31

The acinar distribution of glutathione S-transferase (GST), glutathione peroxidase (GPx), glutathione reductase (GR), and glucose-6-phosphate dehydrogenase (G-6-PDH) was examined by analyzing periportal (p.p.) and perivenous (p.v.) rat hepatocytes selectively isolated by the digitonin-collagenase perfusion. The cytosolic GST activity was higher in p.v. cells, but the microsomal GST and cytosolic GR were found to be evenly distributed in the acinus. In contrast, the activity of both the Se-dependent GPx and the microsomal (Se-independent) GPx, as well as G-6-PDH, was much lower in the p.v. than in the p.p. cells. The heterogeneous distribution of GST, GPx and G-6-PDH was confirmed by analyzing liver perfusion effluents collected after ante- or retrograde digitonin infusion. The relatively low activities of GPx and G-6-PDH in the p.v. cells could partly explain the susceptibility of this region to chemical injury.
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PMID:Acinar distribution of glutathione-dependent detoxifying enzymes. Low glutathione peroxidase activity in perivenous hepatocytes. 359 5

The acute oral LD50 of 2,4-dichlorophenol (2,4-DCP) employing corn oil as vehicle was determined to be 1352 mg/kg for female and 1276 mg/kg for male CD-1 mice. CD-1 mice of both sexes were exposed to 2,4-DCP in drinking water containing 10% Emulphor for 90 days at concentrations of 0.2, 0.6, and 2.0 mg/ml providing theoretical daily doses of 50, 150, and 500 mg/kg. These concentrations resulted in mean daily doses of 50, 143, and 491 mg/kg for females and 40, 114, and 383 mg/kg for males. In both sexes, fluid consumption was lower in the vehicle control group (10% Emulphor) and in the 2,4-DCP treated groups than in the naive controls (deionized water). There were no biologically significant differences in body weight gain between females or males in the vehicle control and experimental groups. No differences were found in terminal organ weights or organ weight ratios in either sex. Hematological differences were observed in males only and included an increase in leukocytes (high dose) and an increase in polymorphonuclears (low dose). Clinical chemistry parameters were altered in females only and included a decrease in creatinine (low dose), an increase in BUN/creatinine ratio (mid dose), and an increase in ALP (high dose). In an assessment of the hepatic microsomal mixed function oxidase system, no significant differences were found in the components of the system, component activity, the kinetics of ethylmorphine N-demethylase, or the metabolism of testosterone.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Acute and subchronic toxicity of 2,4-dichlorophenol in CD-1 mice. 400 6

A new membrane-bound dipeptidyl carboxyhydrolase has been identified in bovine atrial tissue, and has been partially purified after extraction with Triton X-100. This enzyme, found in quantities of 0.01-0.03 units/g tissue assayed with Bz-Gly-His-Leu, is potentially capable of hydrolyzing atriopeptin II to atriopeptin I. The enzyme is located in the microsomal fraction and in sucrose density fractions enriched for atrial granules. The enzyme is completely inhibited by reagents for heavy metals such as EDTA, o-phenanthroline, dithiothreitol, and mercaptoethanol. The latter two compounds are also disulfide reagents. The atrial enzyme is also inhibited by D-2-methyl-3-mercaptopropanoyl-L-Pro(Captopril), 3-mercaptopropanoyl-L-Pro, 2-D-methylsuccinyl-L-Pro, and bradykinin potentiating factor, all inhibitors of the angiotensin I-converting enzyme. However, the atrial enzyme differs from the converting enzyme in a number of kinetic and molecular properties. Its activity increases with ionic strength, but the atrial enzyme does not have a chloride dependence for Bz-Gly-His-Leu hydrolysis; the pH optimum, 7.3, is slightly lower, and it is 5500 times less sensitive to the very potent converting enzyme inhibitor, D-Cys-L-Pro. The strokes radius of the atrial enzyme is 5.00 nm as compared to 4.10 nm, and its molecular weight is 240,000 compared to 145,000. Ventricular tissue, which does not contain the atrial peptides, does not contain the dipeptidyl carboxyhydrolase enzyme.
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PMID:Atrial tissue contains a metallo dipeptidyl carboxyhydrolase not present in ventricular tissue: partial purification and characterization. 638 59

"Enkephalinase," a membrane-bound peptidase hydrolyzing the Gly3-Phe4 amide bond of enkephalins, initially characterized in brain, was purified from a rat kidney microsomal fraction. After differential solubilization with Triton X-100, the use of DEAE-Sephadex, concanavalin A, and hydroxylapatite chromatography led to a 2000-fold purification, close to homogeneity. Renal enkephalinase appears to be a glycoprotein Mr = 92,000-95,000 with catalytic properties and sensitivity to chelating agents and inhibitors (Thiorphan, phosphoramidon) very similar to those of the cerebral enzyme. The enzyme co-purified until the final step with "renal brush-border neutral proteinase" (EC 3.4.24.11) activity assayed with 125I-insulin B chain as substrate and displaying similar sensitivity to inhibitors. The specificity of the purified enkephalinase has been studied using either peptides derived from the enkephalins or model peptides of general formula (Ala)m-Tyr-(Ala)n as substrates. In all cases the bond cleaved was that involving the amino group of an aromatic residue, specificity being also defined by the nature of the neighboring residue on the COOH-terminal side. A free carboxyl in the latter residue was essential in the two series of substrates, indicating that enkephalinase more efficiently functions as a dipeptidyl carboxypeptidase than as an endopeptidase.
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PMID:Enkephalinase from rat kidney. Purification, characterization, and study of substrate specificity. 638 47

Activity levels of 7-ethoxycoumarin O-deethylase (ED), aminopyrine N-demethylase (APD), p-nitroanisole O-demethylase (p-NAD) and glucose-6-phosphate dehydrogenase (G-6-PDH) were determined in incubation mixtures for the liver-microsomal assay (LMA) at time 0 and after 1 and 2 h incubation under conditions for mutagenic assay. The experiments were performed with S9 liver fractions from mice (induced with Na-phenobarbital and beta-naphthoflavone) and rats (induced with Aroclor 1254) with and without G-6-PDH in the incubation mixtures. In the absence of G-6-PDH the activities were significantly lower at time 0 in the mouse. The pattern of stability, however, was similar for the activities, with an increase of stability after 1 and 2 h of pre-incubation (an exception for p-NAD). Only ED activity showed a similar behaviour in the rat. No differences were present for APD and p-NAD activities at time 0 in the rat, but the enzyme stabilities were significantly decreased after 2 h of incubation (about 15% and 10% for APD and p-NAD respectively) in the absence of G-6-PDH. At time 0, the amounts of G-6-PDH differed between mouse and rat fractions; however, during the incubations for LMA they decreased by about 57% and 53% for the two species, respectively. In addition to the above biochemical results, the presence of exogenous G-6-PDH in the incubations for the mutagenic assay, significantly increased the mitotic gene conversion and mitotic crossing-over of dimethylnitrosamine (DMN) and AR2MNFN (a nitroimidazo[2,1-b]thiazole) in the D7 strain of Saccharomyces cerevisiae.
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PMID:NADPH-generating system: influence on microsomal mono-oxygenase stability during incubation for the liver-microsomal assay with rat and mouse S9 fractions. 639 64

To clarify the mechanism of production of des-gamma-carboxy (abnormal) prothrombin (DCP) by hepatocellular carcinoma (HCC), we measured the levels of vitamin K, DCP, immunoreactive prothrombin and the activity of gamma-glutamyl carboxylase in liver tissues from HCC patients and in the medium of cultured human hepatoma cells. There was no significant difference in vitamin K (K1, MK-4) contents between HCC and non-HCC cirrhotic liver tissues. The activity of gamma-glutamyl carboxylase per unit amount of endogenous microsomal prothrombin precursor was decreased in HCC tissue compared with non-HCC liver tissue (positive plasma DCP: 335 +/- 72 vs 372 +/- 67, negative plasma DCP: 370 +/- 84 vs 393 +/- 56 nmol/min per mg prothrombin precursor, P > 0.05), although the total incorporation of 14COOH into microsomal precursor protein was higher in the former. By contrast, levels of DCP and immunoreactive prothrombin in HCC tissue were greater (P < 0.05) than those in non-HCC cirrhotic liver tissue. Furthermore, production of large amounts of immunoreactive prothrombin was observed in human hepatoma cells huH-1 and huH-2, which produced large amounts of DCP. These results suggest that there was excessive synthesis of prothrombin precursors by human HCC tissue and hepatoma cell lines huH-1 and huH-2. Thus, excessive synthesis of prothrombin precursors seems to be the main mechanism of DCP production by HCC.
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PMID:Levels of vitamin K, immunoreactive prothrombin, des-gamma-carboxy prothrombin and gamma-glutamyl carboxylase activity in hepatocellular carcinoma tissue. 762 Jan 13

The present study was carried out to investigate the efficacy of liposome-associated alpha-tocopherol in treating pulmonary damage caused by paraquat exposure. alpha-Tocopherol liposomes (8 mg alpha-tocopherol/kg body weight) or plain liposomes were intratracheally instilled into the lungs of rats 24 h after paraquat treatment (20 mg/kg, ip); treated animals were killed 8, 24 or 48 h after administration of the liposomal preparations. Lungs of animals exposed to paraquat were extensively damaged as evidenced by an increase in lung weight and decreases in pulmonary angiotensin converting enzyme and alkaline phosphatase activities. Also, paraquat treatment resulted in a significant reduction in glutathione (GSH) concentration in the lung and an elevation in microsomal lipid peroxidation levels, as measured by the formation of diene conjugates. Treatment of paraquat-injected rats with plain liposomes did not significantly alter paraquat-induced changes of all parameters examined. On the other hand, treatment of rats with alpha-tocopherol liposomes, 24 h after paraquat administration, resulted in a significant increase in pulmonary alpha-tocopherol concentrations as well as a reduction in paraquat-induced changes in lipid peroxidation, GSH concentration, and lung angiotensin converting enzyme and alkaline phosphatase activities. The results of the present study suggest that alpha-tocopherol, administered directly to the lung in a liposomal form, may serve as a potentially effective pharmacological agent in the treatment of paraquat-induced lung injury.
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PMID:Liposomal alpha-tocopherol alleviates the progression of paraquat-induced lung damage. 777 11

Angiotensin I-converting enzyme (kininase II, ACE) is a transmembrane ectoenzyme of vascular endothelial cells that is also secreted in plasma. To understand why plasma ACE levels are elevated in children compared with adults, the age-related changes in ACE mRNA and enzyme levels were studied in 1-day- to 3-mo-old rats. In the lung, a rich source of endothelial ACE, the abundance of ACE mRNA and the microsomal ACE concentration increased progressively and tripled during the first 3 mo. This large increase reflects, at least in part, development of the capillary network. In plasma, ACE levels rose dramatically a few days after birth and decreased toward adult values after the 14th day of life. Because the elevation of ACE in plasma was contemporary to thyroid maturation, the effect of perinatal suppression of thyroid function by propylthiouracil was studied. Hypothyroidism slightly delayed the evolution of ACE in lung but blunted the postnatal rise in plasma ACE levels. A 3,5,3'-triiodothyronine injection to 14-day-old hypothyroid rats failed to alter ACE mRNA levels in the lung. Thus thyroid hormones are involved in the postnatal rise in plasma ACE levels but act probably on the posttranslational proteolytic pathway involved in ACE secretion by endothelial cells or on an unknown extrapulmonary ACE source. ACE gene expression is also developmentally regulated in epithelia and male germinal cells. In the intestine, ACE mRNA levels and ACE activity were very high at birth and then decreased dramatically during the next 2 wk. In the kidney, they were low and decreased further during growth.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Regulation of ACE gene expression and plasma levels during rat postnatal development. 797 26


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