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

---

Query: EC:3.1.3.9 (glucose-6-phosphatase)
3,081 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The acute effects of the PCB (polychlorinated biphenyls) mixture (Aroclor 1254) on microsomal enzymes and on synthesis and turnover of microsomal and cytoplasmic lipids of rat liver were investigated. Six daily i.p. injections of 25 and 50 mg PCB/kg body weight resulted in increased liver weight and liver to body weight ratios. When compared to controls PCB treatment resulted in a six-fold increase in amount of cytochrome P-450. Activities of NADPH-cytochrome c reductase, ethylmorphine demethylase and inosine diphosphatase were increased whereas glucose-6-phosphatase values were decreased by PCB exposure. Analysis of liver homogenate and microsomal fraction revealed an increase in lipid in PCB-exposed animals. Phospholipids, cholesterol and triglyceride were significantly increased after PCB exposure; however, the greatest percentage increase was seen in the triglyceride pool. The finding of an increase in microsomal triglyceride to phospholipid ratios with exposure to PCB is suggestive of an increase in membrane-enclosed lipid (liposomes). Studies with labelled glycerol indicated that the PCB-induced fatty liver resulted from increased half life but not increased synthesis of liver lipid moieties. The rate of incorporation of leucine into microsomal membrane and albumin was somewhat enhanced in rats exposed to PCB indicative of increased protein synthesis. Morphological studies showed increased occurrence of lipid material, both in cytoplasmic droplets and within rough and smooth-surfaced endoplasmic reticulum. Proliferation of smooth endoplasmic reticulum and flattened Golgi cisternae with no secretion granules containing lipoprotein particles characterized the liver from animals exposed for 6 days. The increase in lipid within membranes of the endoplasmic reticulum together with the flattened Golgi lacking typical secretory vesicles indicates a defect in transport of lipoproteins from the endoplasmic reticulum to the Golgi apparatus and may be the cause of the PCB-induced fatty liver.
...
PMID:Studies on the cellular toxicity of polychlorinated biphenyls (PCBs). I. Effect of PCBs on microsomal enzymes and on synthesis and turnover of microsomal and cytoplasmic lipids of rat liver- a morphological and biochemical study. 9 1

Male Sprague-Dawley rats consumed a diet to which 100 ppm of various polychlorinated biphenyl (PCB) mixtures (Aroclors 1248, 1254, and 1262) were added for one year. Rats were hepatectomized at 13, 26, and 52 weeks during feeding and at 13 weeks following the discontinuation of the PCB diets. The liver homogenates of these rats had an increase in protein and RNA on a DNA basis and an increase in lipid and a decrease in DNA on the liver weight basis. The hepatic microsomes from these livers also had an increase in protein and cytochrome P-450. The RNA/microsomal protein levels were decreased, and no marked alterations were recorded for the phospholipids and cholesterol on a microsomal protein basis. Increased enzymatic activity was recorded for N-demethylase and nitroreductase. However, the specific activity of glucose-6-phosphatase was decreased throughout the treatment period.
...
PMID:Responses of rats exposed to polychlorinated biphenyls for fifty-two weeks. II. Compositional and enzymatic changes in the liver. 12 Jan 38

The activities of liver microsomal enzymes were studied in preparations from unanesthetized rats and rats anesthetized for one hour with nitrous oxide, diethyl ether, halothane or chloroform. Most of the enzymes studied were cytochrome P-450-dependent oxygenases that hydroxylate endogenous substrates. The other microsomal enzymes, assayed for comparison, included the cytochrome P-450-dependent aminopyrine demethylase, glucose-6-phosphatase, a dehydrogenase, and NADPH-cytochrome P-450 reductase. No anesthetic was associated with a significant change in activity of any enzyme studied. In rats pretreated with phenobarbital no anesthetic except chloroform changed enzymic activity. All hydroxylations were inhibited markedly by chloroform, as were a microsomal dehydrogenation, hydrolysis of glucose-6-phosphate, and NADPH-cytochrome P-450 reductase activity. Administration of alpha-tocopherol did not prevent the inhibition associated with chloroform in phenobarbital-induced animals. It is concluded that cytochrome P-450-dependent hydroxylations involved in metabolic processes normally proceeding in the endoplasmic reticulum of the liver are not permanently affected by the anesthetics used in this study. The inhibitory effect of chloroform after pretreatment with phenobarbital is unspecific and affects a large number of different microsomal enzymes. Evidence that mechanisms other than lipid peroxidation may be responsible for the toxic effects of chloroform in the liver is presented.
...
PMID:Inhalation anesthetics and cytochrome P-450-dependent reactions in rat liver microsomes. 16 17

The PolytronR and Dounce homogenizers have been evaluated for preparation of homogenates of rat liver prior to isolation of subcellular fractions by differential centrifugation. Marker enzymes used to evaluate the subcellular fractions included cytochrome oxidase, monoamine oxidase, D-amino acid oxidase, acid phosphatase, glucose-6-phosphatase, ethyl morphine demethylase, and lactate dehydrogenase. No significant difference in the distribution of enzymes (percent recovery or specific activity) was observed between the two methods of homogenization. In addition, there were no significant differences in the ultrastructural appearances and respiratory control ratios of the mitochondrial fractions prepared by the two methods of homogenization.
...
PMID:Preparation of subcellular fractions from rat liver: comparison of the Polytron with the Dounce homogenizer. 18 48

Since infections with Schistosoma mansoni cause marked histopathological changes in the liver of the host, the effect of this infection on the hepatic drug-metabolizing function was investigated. Severity of Schistosomiasis was determined by worm counts, duration of infection, egg counts and liver weight increases. To overcome difficulties in homogenizing the livers of infected animals, preincubation of the squashed tissues with collagenase and hyaluronidase was used to prepare homogenates. Key component enzyme activities of the hepatic microsomal drug-metabolizing enzyme system (NADPH-cytochrome c reductase and cytochrome P-450) as well as the representative drug-metabolism activities (aminopyrine N-demethylase, aniline hydroxylase, and benzpyrene hydroxylase) were measured for the whole liver and found to be markedly reduced. However, the measurement of microsomal marker enzyme activities (cytochrome b5 and glucose-6-phosphatase) showed significant elevation. To obtain more precise information about the effect of the schistosome infection on the hepatic drug-metabolizing enzyme system, the total activities of microsomal drug-metabolizing enzymes were related to the total microsomal marker enzyme activities in the homogenate.
...
PMID:Effect of Schistosoma mansoni infection on the hepatic drug-metabolizing capacity of mice. 18 61

Primary monolayer culture of adult rat hepatocytes represents a novel and potentially useful technique to study many aspects of hepatic physiology for extended periods of time in vitro (J Cell Biol 59:722-734, 1973). In examining the hepatic drug-metabolizing system in these cells, we have discovered that the conditions of cell culture exert rapid, selective, and reproducible changes in microsomal enzymes. In the 24- to 48-hr period immediately following preparation and culture of the isolated parenchymal cells, the level of the drug-binding microsomal hemoprotein, cytochrome P-450, measured in extracts of cell homogenates, declined to less than 20% of its in vivo level, whereas NADPH-cytochrome c reductase activity was only moderately reduced and glucose-6-phosphatase activity remained unchanged. The activity of aminopyrine-N-demethylase and aniline hydroxylase also fell, paralleling the level of cytochrome P-450. By contrast, p-nitroanisole O-demethylase activity was unchanged in the cultured hepatocytes despite evidence (type I binding spectrum, NADPH requirement, inhibition by carbon monoxide or by SKF 525A) that p-nitroanisole O-demethylase is a cytochrome P-450-dependent enzyme. In culture, as in vivo, aromatic polycyclic hydrocarbons stimulated p-nitroanisole O-demethylase and aryl hydrocarbon (benzo [a] pyrene) hydroxylase activities; however, this effect was unaccompanied by a detectable increase in total carbon monoxide-binding hemoprotein. The data indicate that the profile of microsomal oxidase enzymes and their control undergo striking changes as hepatocytes adapt to cell culture.
...
PMID:Drug metabolism in adult rat hepatocytes in primary monolayer culture. 40 8

Administration of thiobenzamide in a single dose (25 mg/100 g body wt by stomach tube) to male rats induced centrilobular necrosis, which became evident 10 h after the poisoning. In the meantime liver weight and water content underwent changes, glycogen was lost, triglycerides accumulated in the liver while decreasing in serum, [3H] leucine uptake in proteins was impaired and the activity of glucose-6-phosphatase and aminopyrine demethylase decreased. The activity of NADPH-cytochrome c reductase remained unchanged, whereas a reduction of the microsomal cytochrome P-450 occurred. The liver amount of reduced glutathione underwent no significant changes. Pretreatment of the animals with cobalt chloride or 20-methylcholanthrene decreased the liver damage caused by the drug. The in vitro addition of thiobenzamide to liver microsomes resulted in a spectral change. The appearance of conjugated dienes among microsomal lipids from drug-treated rats indicated for a lipoperoxidation taking place in vivo.
...
PMID:Early biochemical liver changes following thiobenzamide poisoning. 51 72

The interaction between amphetamine and synthetic oral contraceptive steroids have been studied in the female rat. A progestational agent, quingestanol acetate, and a standard combination contraceptive (quingestanol acetate/ethynyl estradiol) were given with and without the concurrent administration of amphetamine. Steroid treatments increased the activity of some drug-metabolizing enzymes (aminopyrine N-demethylase, coumarin 3- hydroxylase, hexobarbital oxidase). Other parameters measured remained unaltered (glucose-6-phosphatase, aniline hydroxylase, cytochrome c reductase, cytochrome P 450, microsomal protein and phospholipid contents). Amphetamine treatment alone raised some drug-metabolizing enzymes (coumarin 3-hydroxylase, hexobarbital oxidase), increased microsomal phospholipid content and de novo synthesis, but elicited no effect on other enzymes measured. Amphetamine and quingestanol acetate given together significantly increased some drug metabolizing enzymes while the simultaneous treatment with combined steroids and amphetamine showed the most pronounced action. These experiments thus revealed that at least in the liver of the female rat, amphetamine elicited no overt hepatotoxicity, rather, brought about a weak inductive action of drug metabolizing enzymes. The application of steroid hormones also raised drug metabolism and the interaction between amphetamine and contraceptive steroids showed additive effects.
...
PMID:Influence of oral contraceptives on the acute effect of amphetamine on the hepatic endoplasmic reticulum of the rat. 84 78

Periportal (pp) or perivenous (pv) liver parenchymal cells from female adult Uje: WIST rats were isolated after retro- or antegrade digitonin infusion followed by collagenase perfusion in the opposite direction. The morphological results revealed a distinct acinar-related destruction of the pv- or pp-zone by digitonin. The remaining cells of the respective other zone showed a good structural maintenance. After subsequent conventional collagenase perfusion the yield, viability and structural integrity of the isolated hepatocytes were high. The zonal cell separation was indicated by significant differences in the pp marker glucose-6-phosphatase and the pv marker glutamine synthetase found in the isolated pp or pv cell populations. Under our experimental conditions including the use of female rats, the alanine aminotransferase and glutamate dehydrogenase as well as ethylmorphine N-demethylase and ethoxycoumarin O-deethylase activities were evenly distributed in both preparations. Under stimulating conditions the capacity for urea synthesis was similar in both pv and pp cells.
...
PMID:Biochemical and morphological studies on perivenous and periportal liver parenchymal cells from female rats isolated by digitonin-collagenase method. 168 Jul 46

Experimental infection of golden hamsters with the hookworm, Ancylostoma ceylanicum, caused a profound decline in the hepatic microsomal cytochrome P450 content. Concomitant decrease was also noticed in aminopyrine N-demethylase and benzo[a]pyrene hydroxylase activities. However, aniline hydroxylase activity was only marginally elevated during the infection. Microsomal markers, viz., cytochrome b5, NADH-cytochrome-c reductase, and glucose-6-phosphatase, were not significantly altered. Hepatic tissue exhibited an accumulation of lipids, especially phospholipids, triglycerides, and cholesterol, resulting in fatty necrosis around the central vein region. Isolated hepatic microsomes showed a decrease in phosphatidylcholine content. Impairment in hepatic mixed function oxidase (MFO) activities was further confirmed by prolongation in hexobarbital sleeping time and zoxazolamine-induced paralysis. The hepatic MFO system of A. ceylanicum-infected hamsters responded qualitatively and quantitatively in a manner similar to that of control hamsters, upon stimulation with selective chemical inducers like phenobarbitone and 3-methylcholanthrene. Kinetic and in vitro substrate binding studies revealed that for aminopyrine the substrate affinity and the maximum enzyme activity (Vmax) were decreased, while for aniline the binding affinity was decreased and the binding capacity was enhanced. Results indicate specific/selective impairment of the hepatic microsomal cytochrome P450 system during hookworm infection and may have many practical implications in toxicology and pharmacology.
...
PMID:Hepatic microsomal cytochrome P450 system during experimental hookworm infection. 236 36


1 2 3 4 Next >>

---