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:3.1.3.1 (alkaline phosphatase)
47,916 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Previous studies in vivo and with isolated perfused rat livers have suggested that the deleterious effect of ethanol on hepatic pyridoxal 5'-phosphate metabolism is mediated by acetaldehyde. Inasmuch as acetaldehyde has no effect on the synthesis of pyridoxal phosphate, it has also been postulated that acetaldehyde accelerates pyridoxal phosphate degradation by displacing this coenzyme from binding proteins, which protect it against hydrolysis. To test these hypotheses, studies have been performed with isolated rat hepatocytes, subcellular fractions of rat liver, and human erythrocytes. Ethanol oxidation lowered the pyridoxal phosphate content of isolated liver cells when acetaldehyde oxidation was inhibited by either disulfiram or prior treatment of rats with cyanamide. Additions of 7.5 mM acetaldehyde alone at 40-min intervals to cell suspensions decreased hepatic pyridoxal phosphate content only slightly because acetaldehyde was rapidly metabolized. However, when acetaldehyde oxidation and reduction were inhibited by cyanamide treatment and by 4-methyl-pyrazole and isobutyramide, respectively, a 40% decrease in hepatic pyridoxal phosphate content was observed in 80 min of incubation. In equilibrium dialysis experiments, acetaldehyde, 7.5 and 15 mM, displaced protein-bound pyridoxal phosphate in undialyzed hepatic cytosol and in hemolysate supernate containing added pyridoxal phosphate. In the presence of alkaline phosphatase, acetaldehyde accelerated the degradation of pyridoxal phosphate in dialyzed hemolysate supernate and hepatic cytosol with added pyridoxal phosphate. Acetaldehyde also inhibits tyrosine aminotransferase. The kinetics of inhibition were mixed competitive-noncompetitive with respect to pyridoxal phosphate. These observations support the hypothesis that the deleterious effect of ethanol oxidation on pyridoxal phosphate metabolism is mediated at least in part by acetaldehyde which displaces this coenzyme from protein binding, thereby enhancing its degradation.
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PMID:The role of acetaldehyde in mediating the deleterious effect of ethanol on pyridoxal 5'-phosphate metabolism. 2 31

This study was undertaken to investigate the effect of alcohol on the activity of jejunal disaccharidases (DS). The activity of DS in a preparation of purified brush border membrane of hamster jejunum was measured in the absence and in the presence (0.8 to 6.4% wt/vol) of ethanol. To compare the effect of alcohol on DS with its action on a brush border enzyme of a different group, we also measured the activity of alkaline phosphatase (AP) under similar conditions. Ethanol depressed the activity of sucrase, maltase, and lactase in a dose-dependent and time-dependent manner, but it stimulated the activity of AP. The ethanol-induced inhibition of DS was completely reversible. Kinetic studies indicate that ethanol depressed the Vmax and increased the Km of sucrase and lactase. The Vmax of maltase also decreased, but the Km of this hydrolase was not affected by ethanol. From the results of this study it would appear that acute exposure of the jejunal brush border to ethanol depresses the DS activity of the membrane and that (because the AP was not depressed) the ethanol-induced inhibition of DS is not the result of a general inhibition of all enzymes of the brush border.
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PMID:Effect of ethanol on disaccharidases of hamster jejunal brush border membrane. 11 61

The effect of graded (5, 10, 20, and 50%) chronic ethanol administration on the intestinal brush border enzymic activities has been investigated in the rat at three levels of the intestinal tract (duodenum, jejunum, ileum). Ethanol has been administered for 8, 15, 30, and 90 days. A 30% to 50% decrease of sucrase and alkaline phosphatase results, showing that the effect of alcohol appears in the first 8 days of intoxication is not reversible after 8 days of an alcohol-free diet. The effect of ethanol is not limited to disaccharidases. Impairment of alkaline phosphatase, peptidases and also enterokinases is observed. The decrease is more marked in the duodenum and jujunum than the ileum. The decrease of enzymic activity is generally maximal after 30 days of intoxication. There is then little further deterioration or even significant improvement. At the 30th day of ethanol administration, a clearcut dose-response relationship has been established. The results obtained suggest that ethanol exerts an effect on the intestinal mucosa which is not directly correlated to morphological villus changes.
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PMID:Intestinal brush border enzymes and chronic alcohol ingestion. 57 90

Ethanol feeding to rats for 40 days enhanced (p < 0.001) the activities of alkaline phosphatase, sucrase, gamma-glutamyltransferase (GTP), and p-nitrophenyl (PNP)-beta-D-galactosidase (p < 0.05) with no change in leucine amino peptidase (LAP) and PNP-beta-D-glucosidase activities in intestine compared with control rats. The activities of alkaline phosphatase, sucrase, and GTP were diminished (p < 0.01) in ethanol-fed malnourished rats. There was no change in LAP activity, but the levels of glucosidase and galactosidase were elevated under these conditions. Brush-border sialic acid, fucose, hexose, and hexosamine contents were elevated in ethanol-fed protein-deficient animals. Ethanol administration to normally fed rats elevated the membrane sialic acid and hexose contents, reduced fucose content, and had no effect on brush-border hexosamine content compared with the control group. These results are in agreement with data on lectin binding to brush borders under these conditions. Alcohol ingestion reduced the incorporation of [14C]-glucosamine into brush borders in rats maintained on an 18% protein diet but augmented the incorporation of [14C]-glucosamine and [14C]-mannose in protein-malnourished membranes. These observations suggest that nutrition status influences the sensitivity of microvillus membrane glycosylation to ethanol feeding in rat intestine.
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PMID:Chronic ethanol feeding and microvillus membrane glycosylation in normal and protein-malnourished rat intestine. 142 85

Serum activities of alanine-aminotransferase (ALAT, EC 2.6.1.2), aspartate-aminotransferase (ASAT, EC 2.6.1.1), lactate dehydrogenase (LDH, EC 1.1.1.27), and alkaline phosphatase (AP, EC 3.1.3.1) were increased significantly after a dose of 0.16 g/kg/b. w. (ip.) carbon tetrachloride (tetrachloromethane) in rats pretreated with 10% (v/v) ethanol for one and 10 weeks in comparison with water/carbon tetrachloride-treated animals. At the end of 30 and 52 weeks of ethanol consumption these levels were very slightly increased or not detectable. Ethanol treatment alone did not cause an increase in serum enzyme activities or histological liver damage, but caused a diminished intake of fluid and food and in some cases also a reduction of weight gain in the animal body. Significant decrease in body weight after carbon tetrachloride was more evident in rats pretreated with ethanol (1 week greater than 10 greater than or equal to 52 weeks) than in water drinking animals, the lethality caused by carbon tetrachloride was also higher after one and 10 weeks than after 30 to 52 weeks of ethanol pretreatment. The results indicate a decrease of carbon tetrachloride toxicity with increased duration of ethanol pretreatment. This phenomenon could be attributed to reduced sensibility to those alcohol effects which are responsible for increase of carbon tetrachloride toxicity.
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PMID:Influence of ethanol pretreatment of differing duration on toxic effects of carbon tetrachloride in rats. 208 Sep 8

The effects of ethanol and closely related alcohols on the cell-substrate adhesion of embryonal carcinoma cells were studied in microtiter wells using the enzyme cytochemical alkaline phosphatase technique and an ELISA reader. Three embryonal carcinoma cell lines (NF-1, NE and F9) were used. Prior to plating of cells the wells were coated with laminin, fibronectin or collagen type I. NF-1 cells adhered only to laminin; NE adhered to all substrata and uncoated wells equally well; F9 adhered only to fibronectin and laminin coated wells. Ethanol reduced the binding of cells to laminin and collagen type I but did not affect the binding of NE or F9 cells to fibronectin. The effect of ethanols was dose dependent; it lasted as long as an adequate concentration of this alcohol was maintained in vitro, and it was reversible. Other short chain alcohols inhibited the binding of cells to laminin proportionately to their membrane/buffer partition coefficients. These data show that various embryonal carcinoma cells differ with regards to their capacity to adhere to different extracellular matrix components. Cell adhesion to some but not all substrates can be prevented by ethanol and related short chain alcohols. The effects of alcohols on the adhesion of embryonal carcinoma cells to various substrates may be relevant for the elucidation of the fetal alcohol syndrome.
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PMID:Effects of alcohols on mouse embryonal carcinoma-substrate adhesion. 208 93

We have conducted studies to obtain practical knowledge regarding the stability, digestion, and analytical determination of the content of 8-hydroxy-2-deoxy-guanosine (8-OHdG) in oxidatively damaged DNA. Utilizing H2O2 plus uv light to form oxidatively damaged DNA, we found that storage of the DNA at -20 degrees C at alkaline pH caused a significant loss of 8-OHdG, whereas storage at -20 degrees C at neutral or acidic pH prevented loss of 8-OHdG. The 8-OHdG within DNA is stable at 100 degrees C for at least 15 min. Formation of 8-OHdG within DNA using uv light and H2O2 as a hydroxyl free radical-generating system yields the highest amounts when low levels of phosphate buffer are used; but the use of Tris or citrate buffers causes a lower yield of 8-OHdG because these buffers act as scavengers for the hydroxyl free radicals. Independent assessment of hydroxyl free radical flux by the use of salicylate trapping allows assessment of competitive radical reactions. Ethanol washing of plastic microfuge tubes prior to DNA enzymatic digestion improved the yield of 8-OHdG and reduced the variability between samples. Digestion of the oxidatively damaged DNA by the use of a method involving DNase I, endonuclease, phosphodiesterase, and alkaline phosphatase produced the highest yield of 8-OHdG.
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PMID:Conditions influencing yield and analysis of 8-hydroxy-2'-deoxyguanosine in oxidatively damaged DNA. 222 56

In vitro studies indicate that low concentrations of ethanol can have direct effects on bone formation and resorption. Bone resorption was increased when embryonic chick tibiae were exposed to ethanol at 0.03-0.3% (v/v), and bone formation was inhibited when tibiae were exposed to 0.2% ethanol in the presence of NaF or parathyroid hormone (P less than 0.01 for each). Ethanol also had direct effects on isolated bone cells in vitro, increasing both cAMP and PGE2 production (P less than 0.001 for each), and affecting cell proliferation in a biphasic, time- and dose-dependent manner. After 24 h of exposure, 0.03% ethanol increased bone cell proliferation (P less than 0.001), but 0.3% ethanol was inhibitory (P less than 0.01). Paradoxically, mitogenic doses of ethanol prevented the effects of two other mitogens, NaF and human skeletal growth factor, to increase bone cell proliferation (P less than 0.001). But how were these effects produced? Several observations suggest that these direct effects of ethanol on skeletal tissues in vitro were mediated by changes in bone cell membrane fluidity. (a) Dimethyl sulfoxide, ethylene glycol, and lecithin, which act, like ethanol, to increase membrane fluidity, mimicked the effects of ethanol on bone cell proliferation. Dimethyl sulfoxide also mimicked the effect of ethanol to increase cAMP (P less than 0.001). (b) Cholesterol, which decreases cell membrane fluidity, acted oppositely to ethanol and enhanced the mitogenic response to human skeletal growth factor (P less than 0.001). (c) Preincubation of calvarial cells with ethanol or with cholesterol altered the in situ reaction kinetics of the membrane-bound enzyme, alkaline phosphatase. Together, these data demonstrate that ethanol has direct effects on skeletal tissue in vitro, and suggest that those effects may be secondary to changes in bone cell membrane fluidity.
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PMID:Direct effects of ethanol on bone resorption and formation in vitro. 298 96

Mechanisms of alcoholic liver disease are still ill defined. We evaluated in two outbred lines of mice whether chronic ingestion of ethanol alters the lipid composition and/or enzyme activity of liver plasma membranes. Two mouse lines with different sensitivities towards the hypnotic effect of ethanol, designated long sleep and short sleep, were fed a liquid diet containing ethanol for 30 days. Ethanol intake reached 30 gm per kg per day in both lines, and serum ethanol levels were similar. In addition, hepatic triglyceride levels were similarly increased 2-fold with ethanol feeding. The following effects of ethanol treatment were observed in liver plasma membrane fractions: (i) Na+,K+-ATPase was significantly increased to 26% above control in long sleep only; (ii) alkaline phosphatase activity was 2-fold increased in both lines; (iii) 5'-nucleotidase, leucine aminopeptidase and Mg2+-ATPase activities remained unchanged in both lines; (iv) unesterified cholesterol and total phospholipid contents were unaltered in both lines, and (v) cholesteryl esters were increased in both lines, but to a greater extent in short sleep (1.5 vs. 4-fold). Thus, chronic ethanol ingestion induces specific alterations in liver plasma membrane structure and function, suggesting that adaptive responses to ethanol may be determined in part by inherited factors.
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PMID:Effect of chronic ethanol administration on enzyme and lipid properties of liver plasma membranes in long and short sleep mice. 299 Nov 3

The metabolic effects of ethanol are due to a direct action of ethanol or its metabolites, changes in the redox state occurring during its metabolism, and modifications of the effects of ethanol by several nutritional factors. Ethanol causes hyperglycemia or hypoglycemia depending whether or not glycogen stores are adequate, inhibits protein synthesis, and results in a fatty liver and elevations in serum triglyceride levels. Increases in serum lactate, results from the increased reduced nicotinamide-adenine dinucleotide/nicotinamide-adenine dinucleotide + (NADH/NAD+) ratio, and hyperuricemia probably occurs owing to the increased turnover of adenine nucleotides after ethanol ingestion. Ethanol decreases thiamine absorption and decreases the enterohepatic circulation of folate. Acetaldehyde, the major metabolite of ethanol, increases the degradation of pyridoxal 5'-phosphate by displacing it from its binding protein and making it susceptible to hydrolysis by membrane-bound alkaline phosphatase. Chronic ethanol administration also results in decreased vitamin A stores and reduced bone mass and blood levels of 25-hydroxyvitamin D. The mechanism whereby ethanol affects these vitamins and their associated enzymes is unknown.
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PMID:The effect of ethanol and its metabolites on carbohydrate, protein, and lipid metabolism. 329 39


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