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Query: UNIPROT:P06889 (Mol)
 630,302 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Catecholamines and thyroid hormones have a similar influence on heart function and metabolism, but this may occur in a differential manner and to a different extent. In this study, the effects of norepinephrine (NE) and of triiodothyronine (T3) were studied in regard to the function of the left (LV) and right ventricle (RV) and to the oxidative pentose phosphate pathway (PPP). NE was applied in rats as continuous i.v. infusion (0.2 mg/kg/h) for three days. T3 was given as daily s.c. injections (0.2 mg/kg) for the same period of time. LV and RV function was measured in the closed-chest trapanal-anesthetized animals using special Millar ultraminature catheter pressure transducers. NE induced an increase in heart rate, in mean arterial pressure, and in total peripheral resistance (TPR). The cardiac RNA/DNA and the left ventricular weight/body weight ratios were increased by about 40%. These effects were prevented by simultaneous alpha- and beta-receptor blockade with prazosin and metoprolol, respectively, but not by verapamil which abolished the hemodynamic effects. RVSP was significantly elevated by NE in a dose-dependent manner. The functional effects of T3 on the LV were not as pronounced as those induced by NE. Heart rate and LV dp/dtmax were increased by T3, and this increase was prevented by concomitant beta-receptor blockade with metoprolol. In contrast to NE, T3 induced an increase in cardiac output and a concomitant decrease in TPR. The RNA/DNA ratio was elevated and cardiac hypertrophy had developed after treatment for three days with T3. These changes were not affected by beta-receptor blockade with metoprolol. RVSP was increased by T3 to a lesser extent than with NE. In metabolic terms it turned out that only NE, but not T3 had a stimulating effect on the cardiac PPP. NE increased the mRNA and activity of glucose-6-phosphate dehydrogenase (G-6-PD), the first and regulating enzyme of this pathway. However, there was no effect of T3 on G-6-PD activity nor on 6-phosphogluconate dehydrogenase activity, one of the following enzymes in the pathway within the first 5 days of T3 treatment. These results demonstrate that the functional effects of T3 were not as pronounced as or even different from those of NE, and that T3 lacked a stimulating effect on the cardiac PPP.
Mol Cell Biochem
PMID:Response of the rat heart to catecholamines and thyroid hormones. 749 38

Intravenous administration of a single dose (100 micrograms/kg bw) of recombinant tumour necrosis factor-alpha (TNF, cachectin) to rats increased the rate of in vitro fatty acid synthesis in interscapular brown adipose tissue (IBAT) from both glucose and alanine, without changes in the oxidation of these substrates to 14CO2. Lactate production and glycerol release were also unaffected by treatment with the cytokine. Additionally, the presence of TNF in the incubation media did not affect fatty acid synthesis, suggesting an indirect effect of the cytokine. The activities of different enzymes of glucose and alanine metabolism such as hexokinase, phosphofructokinase, pyruvate kinase, glucose-6-phosphate dehydrogenase and alanine transaminase, did not suffer changes as a consequence of TNF administration. The same applied to the enzymatic activities involved in fatty acid synthesis such as fatty acid synthase, acetyl-CoA carboxylase and ATP-citrate lyase. Conversely, citrate levels in IBAT were increased in animals treated with TNF, suggesting that it could be the cause for the increased fatty acid synthesis in this tissue.
Mol Cell Biochem 1995 Feb 23
PMID:Metabolic effects of tumour necrosis factor-alpha on rat brown adipose tissue. 759 46

6-Phosphogluconate dehydrogenase (6PGDH) from rat-liver and kidney-cortex cytosol has been partially purified and almost completely isolated (more than 95%) from glucose-6-phosphate dehydrogenase activity. The purification and isolation procedures included high-speed centrifugation, 60-75% ammonium-sulphate fractionation, by which both hexose-monophosphate dehydrogenases activities were separated, and finally the protein fraction was applied to a chromatographic column of Sephadex G-25 equilibrated with 10 mM Tris-EDTA-NADP buffer, pH 7.6, to eliminate any contaminating metabolites. The kinetic properties of the isolated partially purified liver and renal 6PGDH were examined. The saturation curves of this enzyme in both rat tissues showed a typical Michaelis-Menten kinetic, with no evidence of co-operativity. The optimum pH for both liver and kidney-cortex 6PGDH was 8.0. The Km values of liver 6PGDH for 6-phosphogluconate (6PG) and for NADP were 157 microM and 258 microM respectively, while the specific activity measured at optimum conditions (pH 8.0 and 37 degrees C) was 424.2 mU/mg of protein. NADPH caused a competitive inhibition against NADP with an inhibition constant (Ki) of 21 microM. The Km values for 6PG and NADP from kidney-cortex 6PGDH were 49 microM and 56 microM respectively. The specific activity at pH 8.0 and 37 degrees C was 120.7 mU/mg of protein. NADPH also competitively inhibited 6PGDH activity, with a Ki of 41 microM. This paper describes a quick, easy and reliable method for the separation of the two dehydrogenases present in the oxidative segment of the pentose-phosphate pathway in animal tissues, eliminating interference in the measurements of their activities.
Mol Cell Biochem 1995 Mar 23
PMID:Kinetic properties of hexose-monophosphate dehydrogenases. II. Isolation and partial purification of 6-phosphogluconate dehydrogenase from rat liver and kidney cortex. 762 92

We have isolated cDNA clones encoding the pentose phosphate pathway enzymes 6-phosphogluconate dehydrogenase (6PGDH, EC 1.1.1.44) and glucose 6-phosphate dehydrogenase (G6PDH, EC 1.1.1.49) from alfalfa (Medicago sativa L.). These exhibit extensive nucleotide and amino acid sequence similarity to the corresponding genes from bacteria, Drosophila and mammals. Transcripts encoding both enzymes are expressed at high levels in roots and nodules. Exposure of alfalfa suspension cells to an elicitor from yeast cell walls results in co-ordinated increases in transcription rates for both genes, followed by increased steady state transcript levels but only slightly increased extractable enzyme activities, at the onset of accumulation of isoflavonoid phytoalexins. Levels of NADPH and NADP remain relatively constant in alfalfa cells following elicitation. The rapid transcriptional activation of 6PGDH and G6PDH does not therefore appear to be a response to altered pyridine nucleotide redox state. These genes appear to respond to early events in elicitor-mediated signalling rather than to subsequent elicitor-induced changes in secondary metabolism. Hydrogen peroxide, a potential signal for elicitation of anti-oxidative genes in biologically stressed plant cells, did not induce 6PGDH or G6PDH transcripts or enzymatic activity.
Plant Mol Biol 1995 Aug
PMID:Stress responses in alfalfa (Medicago sativa L.) XIX. Transcriptional activation of oxidative pentose phosphate pathway genes at the onset of the isoflavonoid phytoalexin response. 764 Mar 60

Three previously undescribed mutations of the glucose-6-phosphate dehydrogenase (G6PD) gene have been documented in patients with hereditary non-spherocytic hemolytic anemia (HNSHA). In none of the cases have we been able to obtain a sufficient volume of blood to characterize the residual enzyme biochemically. "G6PD Calvo Mackenna" was due to an A-->G transition in cDNA nucleotide 1138 creating an Aat II site and resulting in a substitution of valine for isoleucine at amino acid 380. "G6PD Riley" was due to a T-->C transition at cDNA nucleotide 1139 also changing the 380 isoleucine, in this case to a threonine. "G6PD Wisconsin" was due to an C-->G transversion in cDNA nucleotide 1177, destroying a Aci I site and resulting in a substitution of glycine for arginine at amino acid 393. All of these mutations were in exon 10, where mutations that cause HNSHA appear to be clustered. We present a list of the 83 mutations of G6PD that have been documented to the end of April, 1995.
Blood Cells Mol Dis 1995
PMID:Three new exon 10 glucose-6-phosphate dehydrogenase mutations. 765 62

Genomic and cDNA clones encoding glucose-6-phosphate dehydrogenase (G6PD) were isolated from the fungus Aspergillus niger. Sequence analysis of the glucose-6-phosphate dehydrogenase gene (gsdA) revealed an open reading frame of 1530 bp, encoding a protein of 58,951 kDa. The gsdA gene is interrupted by nine introns the most proximal of which is exceptionally large (348 bp). The region upstream of the ATG contains several C+T-rich stretches. The two major and one minor transcription start points are all located within these regions. In the upstream region several direct and inverted repeats, but no clear TATA or CCAAT boxes can be found. A. niger strains overproducing G6PD were constructed by cotransformation of gsdA subclones. Overexpression of G6PD was shown to be deleterious for the fungus, especially when cotransformants were grown on media containing ammonia. Attempts to construct a gsdA null mutant by gene disruption were unsuccessful.
Mol Gen Genet 1995 Apr 20
PMID:Isolation and characterization of the glucose-6-phosphate dehydrogenase encoding gene (gsdA) from Aspergillus niger. 775 33

The involvement of reactive oxygen species in chromate-induced genotoxicity has been postulated. Because intracellular antioxidants help in eliminating the reactive species of oxygen, we have investigated both the prooxidant and antioxidant status of human leukemic T-lymphocyte MOLT4 cells exposed to nontoxic levels of chromium(VI) in culture. The cells treated with 0-->200 microM potassium chromate in a salts/glucose medium for 2 h were found to contain significantly lower levels of both small molecular weight and macromolecular antioxidants. In particular, the levels of glutathione and ascorbate were found to decrease with increased doses of chromate exposure in a dose-dependent manner. As little as 10 microM chromate was found to decrease these small molecular weight antioxidants significantly (p < 0.01). The macromolecular antioxidants, such as glutathione peroxidase, catalase, glutathione reductase, glucose-6-phosphate dehydrogenase and superoxide dismutase were also significantly (p < 0.01) decreased by exposing the cells to as little as 10 microM chromate. Concomitantly, there was a dose-dependent increase in intracellular H2O2 accumulation in cells exposed to chromium(VI). These results indicate that chromate-induced genotoxicity may be due, at least in part, to decreased levels of intracellular antioxidants in conjunction with an increased production of the reactive oxygen species.
Mol Cell Biochem 1995 Jan 12
PMID:Alterations in the prooxidant and antioxidant status of human leukemic T-lymphocyte MOLT4 cells treated with potassium chromate. 775 43

It has been suggested that along the female genital tract spontaneous lipid peroxidation regulates the limit of the lifetime of spermatozoa. We have studied some aspects of rabbit and mouse spermatozoal metabolism during spontaneous lipid peroxidation in the course of the incubation in media which simulate the oviductal environment. The spermatozoa collected at regular intervals after the beginning of incubation were processed for cytochemical detection of cytochrome oxidase, lactate dehydrogenase and glucose-6-phosphate dehydrogenase activities. Quantitative cytochemical assays were made in situ in individual spermatozoa by microdensitometry. The cytochrome oxidase activity significantly decreased in both species because of damage to mitochondrial enzymes and membranes by radical and non-radical products of lipid peroxidation. The change in lactate dehydrogenase activity indicates that under our experimental conditions the lipid peroxidation process damages membrane permeability more markedly in mouse spermatozoa. The glucose-6-phosphate dehydrogenase activity, which should influence the concentration of reduced glutathione through production of NADPH, is more extensively enhanced in mouse spermatozoa than in rabbit spermatozoa. This is in agreement with the fact that in mouse spermatozoa the glutathione system is the major protective defence against oxidative damage while in rabbit spermatozoa it is superoxide dismutase.
Cell Mol Biol (Noisy-le-grand) 1995 Mar
PMID:Spontaneous lipid peroxidation and sperm metabolism during incubation in media simulating the oviductal microenvironment. 778 44

The effect of dietary vitamin E supplementation upon macrophage metabolism and function was examined in aged rats fed a balanced or a polyunsaturated-rich diet. The following parameters were studied: number of cells in the intraperitoneal cavity, maximal activity of hexokinase, citrate synthase, glucose-6-phosphate dehydrogenase, glutathione peroxidase and phosphate-dependent glutaminase. The consumption of glucose and the production of lactate, hydrogen peroxide and thiobarbituric reactive substances were measured in control ONCO-BCG injected rats. The results indicated that vitamin E has no significant effect on the values of the parameters studied in the macrophages of rats fed a balanced diet both for 3 (mature) or 17 months (aged). This antioxidant did not provoke any response on the changes caused by ageing the animals. However, several of the metabolic and functional alterations in macrophage induced by the polyunsaturated-rich diets were reversed by the inclusion of vitamin E in the diet. These changes were associated with macrophage migration capacity, citrate synthase and glucose-6-phosphate dehydrogenase activities and the content of lipid peroxides. The findings suggest that vitamin E has a beneficial effect for macrophage metabolism and function, but the effects are confined to particular circumstances.
Biochem Mol Biol Int 1994 Aug
PMID:Effect of dietary vitamin E supplementation on macrophage metabolism during ageing. Study in rats fed fat-rich diets during ageing. 784 17

Glucose 6-phosphate dehydrogenase (G6PD) [EC 1.1.1.49] is inactivated by the incubation with cystamine very efficiently, but not by oxidized glutathione. This inactivation advanced following the incubation-time and concentration of cystamine. The inactivated-G6PD is restored its activity by the treatment of thioltransferase with 1 mM cysteamine or reduced glutathione (GSH) much more effectively than only by thiols. For the first time, we suggested thioltransferase can utilize cysteamine in stead of GSH during its thiol/disulfide exchange reaction activity.
Biochem Mol Biol Int 1994 Oct
PMID:Thioltransferase can utilize cysteamine as same as glutathione as a reductant during the restoration of cystamine-treated glucose 6-phosphate dehydrogenase activity. 786 98


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