Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: EC:3.1.3.9 (glucose-6-phosphatase)
 3,081 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Peroxisome proliferation has been induced with 2-methyl-2-(p-[1,2,3,4-tetrahydro-1-naphthyl]-phenoxy)-propionic acid (Su-13437). DNA, protein, cytochrome oxidase, glucose-6-phosphatase, and acid phosphatase concentrations remain almost constant. Peroxisomal enzyme activities change to approximately 165%, 50%, 30%, and 0% of the controls for catalase, urate oxidase, L-alpha-hydroxy acid oxidase, and D-amino acid oxidase, respectively. For catalase the change results from a decrease in particle-bound activity and a fivefold increase in soluble activity. The average diameter of peroxisome sections is 0.58 +/- 0.15 mum in controls and 0.73 +/- 0.25 mum after treatment. Therefore, the measured peroxisomal enzymes are highly diluted in proliferated particles. After tissue fractionation, approximately one-half of the normal peroxisomes and all proliferated peroxisomes show matric extraction with ghost formation, but no change in size. In homogenates submitted to mechanical stress, proliferated peroxisomes do not reveal increased fragility; unexpectedly, Su-13437 stabilizes lysosomes. Our results suggest that matrix extraction and increased soluble enzyme activities result from transmembrane passage of peroxisomal proteins. The changes in concentration of peroxisomal oxidases and soluble catalase after Su-13437 allow the calculation of their half-lives. These are the same as those found for total catalase, in normal and treated rats, after allyl isopropyl acetamide: about 1.3 days, a result compatible with peroxisome degradation by autophagy. A sequential increase in liver RNA concentration, [14C]leucine incorporation into DOC-soluble proteins and into immunoprecipitable catalase, and an increase in liver size and peroxisomal volume per gram liver, characterize the trophic effect of the drug used. In males, Su-13437 is more active than CPIB, another peroxisome proliferation-inducing drug; in females, only Su-13437 is active.
 ...
PMID:Structure, composition, physical properties, and turnover of proliferated peroxisomes. A study of the trophic effects of Su-13437 on rat liver. 0 Apr 6

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 recirculating perfusion of adult rat liver with a Ca-++-free Hanks' solution produces a release of the adhesiveness of cells and a cleaving of the desmosomes. The addition of collagenase and hyaluronidase to the perfusion medium leads to complete dissociation of the liver tissue into a mixture of isolated cells and cell cords in which the hepatocytes remain connected with specific junctional differentiations, namely the gap and tight junctions. Individual cells are released by submitting the suspension of cell trabeculae to a gentle rolling. The gap junctions are ruptured at least in one of the two adjacent cells and remain generally attached to the other cell taking with them a small portion of cytoplasm. This technique of isolation of hepatocytes yields about 60-65% of the parenchymal cells contained in a liver; endothelial cells and other cells of the connective tissue are not recovered. The ultrastructural preservation of the isolated hepatocytes is excellent and the glucose-6-phosphatase activity, confined to the endoplasmic reticulum, appears unaltered in most cells. Protein, DNA and RNA recovery in the preparations of isolated hepatocytes is satisfactory, amounting to 70% of that found in liver homogenate; glycogen, the most labile component examined, is partly lost or degraded during the manipulations. Cell diameters measured by different methods confirm the preservation of the original volume of the in situ hepatocytes and the presence of more than one type of parenchymal cell. By submitting this heterogeneous cell population to an isopycnic density gradient centrifugation, two types of hepatocytes can be distinguished: the light hepatocytes, with a mean diameter of 20.5 mum and a mean density of 1.10, are characterized by an extended smooth-walled endoplasmic reticulum entrapping dispersed alpha-glycogen particles; the heavy hepatocytes, with a mean diameter of 19.0 mum and a mean density of 1.14, present a relatively reduced compartment of smooth endoplasmic reticulum, but large accumulations of glycogen. It is suggested that the cell fraction of low density is enriched in centrolobular cells and the high density fraction in perilobular hepatocytes.
 ...
PMID:Isolation and subfractionation on ficoll gradients of adult rat hepatocytes. Size, morphology, and biochemical characteristics of cell fractions. 16 28

Daily phenobarbital (PB) injections, on 3-7 consecutive days, induce an intense proliferation of smooth endoplasmic reticulum (ER) associated with a decrease of the glucose-6-phosphatase activity. This situation first affects the centrolobular hepatocytes, enhancing the degree of liver lobule heterogeneity. This experimental model was used for isolation and further subfractionation of hepatocytes on Ficoll density gradients, as described in the preceding paper. Profiles of protein, DNA, RNA, glycogen, phosphorylase, and glucose-6-phosphatase were determined all along the gradient. Two liver cell populations were distinguished: (a) light hepatocytes (mean density 1.10) present the same morphological characteristics as centrolobular cells, i.e., an abundant smooth ER composed of tubular elements, numerous small mitochondria, and few glycogen particles; (b) heavy hepatocytes (mean density 1.14) are characterized by large and compact glycogen areas and prominent rough endoplasmic cisternae, as are the perilobular cells. After incubation in the Wachstein-Meisel medium, Centrolobular hepatocytes exhibit dispersed reaction sites of glucose-6-phosphatase activity, whereas perilobular cells present a continuous and intense reaction. Morphometric determinations were carried out for both cell populations. Centrolobular PB hepatocytes are considerably enlarged (mean diameter: 23.7 mum); perilobular hepatocytes have a significantly smaller mean diameter of 19.2 mum, which is close to the values of control liver cells.
 ...
PMID:Isolation of centrolobular and perilobular hepatocytes after phenobarbital treatment. 16 29

DNA-, RNA-, and lipidsynthesis, glucose-6-phosphate-dehydrogenase, glucose-6-phosphatase and succinate-dehydrogenase were studied in the different morphologic stages of blood schizogony of Plasmodium vinckei. For the separation of these stages of the maturation cycle a discontinuous Ficoll-density gradient was developed. By this method the morphologic stages were separated and obtained in sufficient amounts. DNA-, RNA- and lipidsynthesis was not continuous in the intraerythrocytic cycle of the parasite. The glucose-6-phosphate dehydrogenase activity of the infected erythrocytes decreases whereas that of the glucose-6-phosphatase increases in the maturation cycle of P. vinckei.
 ...
PMID:[DNA-, RNA-, lipidsynthesis and the specific activity of the glucose-6-phosphate dehydrogenase and glucose-6-phosphatase in the different morphologic stages of Plasmodium vinckei]. 16 81

The objective of this investigation was to find out whether vitamin E deficiency, apart from influencing the lipid component of cellular membranes, also influences the protein component. For that purpose a number of membrane-bound enzymes in the liver of the Pekin duckling were histochemically, cytochemically, and biochemically examined. Furthermore, cells, cellular membranes, and protein particles in membranes were morphometrically investigated. Histochemically five membrane-bound enzymes appeared to be stimulated in vitamin E deficiency: 5'-nucleotidase, glucose-6-phosphatase, isocitrate dehydrogenase (NADP), tetrazolium reductase (NADH), and tetrazolium reductase (NADPH). 5'-Nucleotidase and glucose-6-phosphatase were also investigated cytochemically and biochemically. The cytochemical localization of these enzymes was identical in control and vitamin E-deficient ducklings. Biochemically, a stimulation of these two enzymes also could be demonstrated. The increase per milligram of DNA appeared to be largest whereas the increase per milligram of protein, per milligram of phospholipid, and per milligram of RNA was only half of the increase per milligram of DNA. This can be explained by the 30 per cent increase of the cell volume in vitamin E deficiency leading to an increase of protein, phospholipid, and RNA per cell. The thickness of membranes and the diameter of protein particles in membranes were measured in liver parenchymal cells. In vitamin E deficiency the thickness of the outer mitochondrial membrane and the diameter of protein particles in this membrane were smaller whereas the thickness of the endoplasmic reticular membrane was larger. The increase of the activities of mitochondrial and microsomal enzymes and the decrease of the thickness of the outer mitochondrial membrane and of its protein particles are interpreted to be the result of the influence of free radicals on membranes with electron transport functions. The increase of 5'-nucleotidase activity in the plasma membrane is likely to have a different cause; it may be related to the transport of nucleotides across this membrane.
 ...
PMID:Cellular membranes and membrane-bound enzymes in vitamin E deficiency. A histochemical, cytochemical, biochemical, and morphologic study of the liver of the Pekin duckling. 16 37

Nuclei, nuclear membranes and rough endoplasmic reticulum (rER) were isolated from onion root tips and stems. Structural preservation and purity of the fractions was determined by electron microscopic and biochemical methods. Gross compositional data (protein, phospholipid, nonpolar lipids, sterols, RNA, DNA), phospholipid and fatty acid patterns, enzyme activities (ATPases, ADPase, IDPase, glucose-6-phosphatase, 5'-nucleotidase, acid phosphatase, and NADH- and NADPH-cytochrome C reductases), and cytochrome contents were determined. A stable, high salt-resistant attachment of some DNA with the nuclear membrane was observed as well as the association of some RNA with high salt-treated nuclear and rER membranes. The phospholipid pattern was identical for both nuclear and rER membranes and showed a predominance of lecithin (about 60%) and phosphatidyl ethanolamine (20-24%). Special care was necessary to minimize lipid degradation by phospholipases during isolations. Nonpolar lipids, mostly sterols and triglycerides, accounted for 35-45% of the membrane lipids. Sterol contents were relatively high in both membrane fractions (molar ratios of sterols to phospholipids ranged from 0.12 to 0.43). Sitosterol accounted for about 80% of the total sterols. Palmitic, oleic, and linoleic acids were the most prevalent acids in membrane-bound lipids as well as in storage lipids and occurred in similar proportions in phospholipids, triglycerides and free fatty acids of the membrane. About 80% of the fatty acids in membrane phospholipids and triglycerides were unsaturated. A cytochrome of the b5 type was characterized in these membranes, but P-450-like cytochromes could not be detected. Both NADH and NADPH-cytochrome c reductases were found in nuclear and rER membranes and appeared to be enriched in rER membranes. Among the phosphatases, Mg2+-ATPase and, to lesser extents, ADPase, IDPase and acid phosphatase activities occurred in the fractions, but significant amounts of monovalent ion-stimulated ATPase, 5'-nucleotidase and glucose-6-phosphatase activities did not. The results obtained emphasize that the close biochemical similarities noted between rER and nuclear membranes of animal cells extend to these fractions from plant cells.
 ...
PMID:Characterization of nuclear membranes and endoplasmic reticulum isolated from plant tissue. 17 22

For the biochemical characterization of a new transplantable hepatoma derived from the MC-29 virus-induced liver tumor, the macromolecular content and the inducibility of glucose-6-phosphatase, glucose-6-phosphate dehydrogenase, and aryl hydrocarbon hydroxylase were compared in chicken liver and in this hepatoma. The alteration of the nucleocytoplasmic ratio was deduced from measurements of DNA, RNA, protein, and phospholipid contents of the whole cell homogenate and cell fractions. The increased nuclear and decreased cytoplasmic content of macromolecules suggests a dominancy of the nuclei in the tumor cells. Glucose-6-phosphatase and aryl hydrocarbon hydroxylase activities were lower by 60 and 80%, respectively, in the highly proliferating hepatoma than in the liver. In contrast, glucose-6-phosphate dehydrogenase activity increased in the hepatoma. However, enzyme inducers, such as methylcholanthrene, hydrocortisone, and insulin, were able to enhance the activity of these enzymes in the liver but had no stimulating effect on the hepatoma.
 ...
PMID:Biochemistry and enzyme induction in MC-29 virus-induced transplantable avian hepatoma. 17 98

In this first paper of a series comparing the membranes of normal lymphocyte populations from male outbred Syrian hamsters with those of neoplastic transformants (GD 248) induced by simian virus 40, a method is described for the isolation of representative plasma membrane (PM) fragments from both cell types. Multiple criteria were used to monitor the purity and yield of PM material after cell disruption by nitrogen cavitation and after membrane fractionation by a combination of differential centrifugation and isopyknic ultracentrifugation in dextran density gradients. Lactoperoxidase-catalyzed radioiodination before cell disruption was used as an extrinsic surface marker; Na+,K+-activated ATPase, as well as alkaline phosphatase, was used as intrinsic functional PM markers. The distribution of nuclei, mitochondria, lysosomes, and endoplasmic reticulum (ER) during fractionation was monitored by the measurement of DNA, succinate dehydrogenase and monoamine oxidase, beta-glucuronidase and glucose-6-phosphatase, and NADH:lipoamide oxidoreductase, respectively. According to the three PM markers employed, a 15- to 20-fold purification (over homogenate) and a PM yield of about 65% were obtained for both cell categories, with negligible contamination by DNA, mitochondria, lysosomes, and er. The procedure also allowed recovery of 60% of the mitochondria free of other cell elements.
 ...
PMID:Membranes of normal hamster lymphocytes and lymphoid cells neoplastically transformed by simian virus 40. I. High-yield purification of plasma membrane fragments. 18 92

It is shown that human embryonic cells transformed by Rous sarcoma virus (stable cell line 23) and those transformed by polyoma virus (stable cell line P-2) are morphologically distinguished from the normal human embryonic cells. The mitotic activity of P-2 cells was 51% and the mitotic activity of 23 cells was 48%. While the mitosis activity of human embryo fibroblast was 28%. The duration of the mitosis of P-2 cells was 20 hours and that of 23 cells was 18 hr. The duration of the mitotic cycle of human embryo fibroblast was 18 hr. The G1 periods lasted 6 hours for both the cell lines; the S period of P-2 cells lasted 8 hr and the S period of 23 cells was 6 hr. Both the cell lines had a high content of RNA, DNA, protein bound SH-groups, and a high activity of acid phosphatase, acid RNAase and glucose-6-phosphatase. The content of glycogen, and acidic mucopolysaccharides, the activity of NADPH-tetrazolium reductase, succinic dehydrogenase of both the lines were the same as in normal human cells.
 ...
PMID:Morphological and histochemical properties of human embryonic cells transformed by Rous and polyoma viruses. 19 87


1 2 3 4 5 6 7 8 9 10 Next >>