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PubMed1970

Effect of diet on linoleic acid desaturation and on some enzymes of carbohydrate metabolism.

The effect of diet on the desaturation of linoleic acid to gamma-linolenic acid by liver microsomal preparations, on blood glucose and insulin levels, and on activities of glucokinase, hexokinase, pyruvate kinase, and alpha-glycerophosphate dehydrogenase have been studied. The female rats used in these experiments were maintained on one of the following dietary regimes: (a) fasted, (b) fasted for 96 hr and refed glucose, (c) balanced diet, (d) carbohydrate-free diet, (e) lipid-free diet, or (f) protein-free diet. Fasting for 96 hr caused a decrease of both linoleic acid desaturation and glucokinase and pyruvate kinase activity together with a slight decrease of the blood insulin level. Alpha-glycerophosphate dehydrogenase activity was not modified. Refeeding of glucose for 50 hr increased the conversion of linoleic acid to linolenic acid as well as the activities of all the enzymes studied except alpha-glycerophosphate dehydrogenase. The increase in desaturation, however, was transient. The feeding of a lipid-free diet did not modify the tested parameters. Feeding a carbohydrate-free diet for 96 hr resulted in increased linoleic acid desaturation but decreased glucokinase and pyruvate kinase activity, thus apparently eliminating a putative correlation between the fatty acid desaturating activity and glycolytic activity or blood insulin levels under these experimental conditions. The findings suggest that dietary proteins may play an important role in determining the level of fatty acid desaturation.

Animals↗

PubMed1978

[Determination of dehydrogenase and acid phosphatase activity in the lymphocytes in hypertension and vasorenal hypertension].

The activity of succinate dehydrogenase, alpha-glycerophosphate dehydrogenase and acid phosphatase in the lymphocytes of peripheral blood was studied in 28 patients with hypertensive disease and vasorenal hypertension (the diagnosis was made on the basis of the findings of angiographic examination) by the method of quantitative cytochemical analysis suggested by R.P. Nartsissov. It was revealed that alpha-glycerophosphate dehydrogenase activity was significantly lower in vasorenal hypertension than in hypertensive disease. The calculation of the difference between the value of succinate dehydrogenase activity and that of alpha-glycerophosphate dehydrogenase activity in these groups was also significant. It is concluded that a complex of cytochemical analysis may be used in differential diagnosis of vasorenal hypertension and hypertensive disease.

Acid Phosphatase↗

PubMed1995

Hepatic mitochondrial respiration and transport of reducing equivalents in rats fed an energy dense diet.

OBJECTIVE: To measure hepatic mitochondrial respiration as well as the ability of hepatic mitochondria to transport reducing equivalents by shuttle systems in rats fed an energy dense diet. DESIGN: Rats were fed a control (CD) or energy dense (ED) diet for 15 days. MEASUREMENTS: State 3 and State 4 oxygen consumption were measured in isolated mitochondria using glutamate+malate or pyruvate+malate as substrate. We also measured malate-aspartate shuttle activity and mitochondrial alpha-glycerophosphate dehydrogenase activity. RESULTS: ED rats, in comparison with CD rats, showed a significantly greater energy intake without a corresponding greater body weight gain and carcass lipid content. Compared to CD rats, ED rats also showed a significant increase in resting metabolic rate, which was abolished by propranolol. Hepatic mitochondrial state 3 respiration using glutamate+malate or pyruvate+malate as substrate as well as malate-aspartate shuttle activity significantly decreased, while mitochondrial alpha-glycerophosphate dehydrogenase significantly increased in ED rats compared to CD rats. CONCLUSIONS: Mitochondrial NADH oxidation is reduced and a greater fraction of cytoplasmic NADH can be transported to the mitochondria through the alpha-glycerophosphate shuttle and oxidized through the respiratory chain from complex II onwards. This mechanism could lead to a decrease in hepatic metabolic efficiency which is in line with the increased energy expenditure occurring in rats fed an energy dense diet.

Animals↗

PubMed1977

Increasing activity of enzymes on pathway of triacylglycerol synthesis during adipose conversion of 3T3 cells.

When preadipose 3T3 cells pass from growing to resting state, they increase their rate of synthesis of triacylglycerol from precursors and convert to adipose cells. The behavior of two enzymes involved in the synthesis of triacylglycerol, glycerophosphate acyltransferase, and malic enzyme have been examined during the adipose conversion of 3T3-F442A in surface culture and in suspension culture stabilized with methylcellulose. Glycerophosphate acyltransferase activity rises sharply during the conversion and reaches a level of 80 times higher than that of another 3T3 subline in which practically no adipose conversion takes place (3T3-C2). The activity of malic enzyme also rises during the adipose conversion of 3T3-F442A and reaches a level of 15-fold higher than that of 3T3-C2. The activity of glycerophosphate acyltransferase responds more sharply than that of malic enzyme but the rise in activity is not sustained as long, so that the relative levels of the two enzymes change during the conversion. The adipose conversion appears to be the result of increases in the activity of the synthesizing enzymes, brought about by either of the two most physiological methods available for arresting the growth of cultured cells.

Adipose Tissue↗

PubMed1996

[The hormonal sensitivity of glomerulonephritis patients].

Hormone sensitivity in patients suffering from glomerulonephritis of nephrotic type was assessed cytochemically by corticosteroid action on activity of mitochondrial enzymes (alpha-glycerophosphate dehydrogenase, succinate dehydrogenase) and by sensitivity of peripheral blood mononuclear cells to antiproliferative effect of dexamethasone in vitro. In glucocorticosteroid-sensitive patients the activity of alpha-glycerophosphate dehydrogenase, succinate dehydrogenase rises in interaction with prednisolone in vitro. In the resistant patients enzymatic activity in lymphocytes came down, peripheral blood mononuclear cells before and in the course of treatment retained resistance to glucocorticoids irrespective of the treatment results. Alpha-glycerophosphate dehydrogenase to succinate dehydrogenase index varied from 0 to 0.33 and 0.4 to 5.1 in the resistant and sensitive patients, respectively.

Adult↗

PubMed1965

FRUCTOSE 1, 6-DIPHOSPHATASE IN STRIATED MUSCLE.

1. The occurrence of fructose diphosphatase in muscle tissue was investigated with reference to the question whether lactate can be converted into glycogen in muscle, as postulated by Meyerhof (1930), fructose diphosphatase being one of the enzymes required for this conversion. 2. Fructose diphosphatase was found in skeletal muscle of man, dog, cat, rat, mouse, rabbit, guinea pig, cattle, sheep, pigeon, fowl and frog. Under the test conditions between 5 and 60 mumoles of substrate were split/g. fresh wt./hr. at 22 degrees . 3. Like liver fructose diphosphatase, the muscle enzyme is inhibited by substrate concentrations above 0.1 mm, by AMP and by trace quantities of Zn(2+), Fe(2+) and Fe(3+); it is ;activated' by EDTA. Inhibitions by the above agents may account for the failure of previous authors to detect the enzyme. 4. Heart muscle of several vertebrate species and the smooth muscle of pigeon and fowl gizzard had no measurable activity. 5. The presence of fructose diphosphatase and the virtual absence of the enzyme systems converting pyruvate into phosphopyruvate means that lactate and pyruvate cannot be converted into glycogen in muscle, whereas the phosphorylated C(3) compounds can. The reconversion into carbohydrate of lactate (which readily diffuses out of muscle) occurs in liver and kidney only. The reconversion of phosphorylated C(3) intermediates (which cannot diffuse out of the tissue) can occur only within the muscle. 6. alpha-Glycerophosphate is probably the main intermediate requiring conversion into glycogen. The possible role of alpha-glycerophosphate formation in vertebrate muscle, already well established in insect muscle, is discussed.

Adenine↗

PubMed1996

Formation of apatite-collagen complexes.

An apatite-collagen complex was prepared in calcium beta-glycerophosphate solutions at pH 9.0 and 37 degrees C with the purpose of developing new bone substitutes that more closely resemble bone than currently available materials. Reconstituted type I collagen as well as sheet collagen were crosslinked in the presence of alkaline phosphatase and egg-yolk phosvitin. The crosslinked collagens were immersed in daily-renewed calcium beta-glycerophosphate solutions for 2 and 4 weeks to induce the deposition of apatite on the collagen fibers. After 2 weeks of reaction, for example, apatites deposited approximately two times the crosslinked collagen in weight. With reconstituted collagen, the complex showed some elasticity but no apatite was visually observed to detach under deformation with fingers and forceps. The complex, moreover, did not disintegrate when immersed in saline or animal blood. Nevertheless, the complex resorbed with no evidence of cytotoxicity when implanted in muscle tissues. These findings suggest that the apatite-collagen complex prepared would be useful as bone substitutes, especially for periodontal osseous lesion repair and alveolar ridge augmentation.

Alkaline Phosphatase↗

PubMed1984

Possible mechanism behind the adjuvant action of phosphate derivatives on rectal absorption of cefoxitin in rats and dogs.

The mechanism underlying the ability of phosphate derivatives to act as adjuvants and coadjuvants was examined in in vivo and in situ preparations in rats and dogs. The adjuvant effect of DL-alpha-glycerophosphate on the rectal absorption of sodium cefoxitin was greatly augmented by the presence of either sodium phytate or sodium tripolyphosphate. These coadjuvants only slightly enhanced cefoxitin rectal absorption when administered alone. Therefore, enhancement of the permeation of tripolyphosphate and phytate by alpha-glycerophosphate may be necessary before the coadjuvants can significantly affect cefoxitin absorption. The inhibitory effect of disodium 4,4'-diisothiocyano-2,2'-disulfonate stilbene, which is known to interact with the amino group in the protein fraction, on enhanced cefoxitin absorption suggests the involvement of the protein fraction in transport of cefoxitin across the rectal membrane.

Adjuvants, Pharmaceutic↗

PubMed2002

Genome-wide screening by cDNA microarray of genes associated with matrix mineralization by human mesenchymal stem cells in vitro.

Using a culture system that facilitates osteogenic differentiation of bone marrow-derived human mesenchymal stem cells, we analyzed gene-expression profiles during the mineralization process by means of a cDNA microarray system consisting of 23,040 genes. We compared expression profiles of the cells at days 3, 15, and 27 of incubation in media containing either a combination of 0.1 microM dexamethasone, 0.05 mM ascorbic acid-2-phosphate, and 10 mM beta-glycerophosphate, dexamethasone only, ascorbic acid-2-phosphate plus beta-glycerophosphate, or medium without any of these osteogenic supplements. Histochemical analysis revealed osteogenic differentiation of cells incubated in the presence of all three agents, but not in the other cultures. Comparison of the expression profiles disclosed transcriptional stimulation of 55 genes and repression of 82 genes among more than 20,000 examined. A set of differentially expressed genes we report here should contribute to a better understanding of the process of mineralization in the matrix surrounding human mesenchymal stem cells.

Antineoplastic Agents↗

PubMed1992

In vitro formation of mineralized nodules by periodontal ligament cells from the rat.

The purposes of this study were to determine whether periodontal ligament (PDL) cells are capable of producing mineralized nodules in vitro and to analyze ultrastructural features of the nodules. Rat PDL cells were obtained from coagulum in the socket at 2 days after tooth extraction and cultured at confluence in standard medium containing Dulbecco's Modified Eagle's Medium supplemented with 10% FBS and antibiotics. To test mineralized nodule formation, cells were further cultured for an additional 3 weeks in the standard medium containing (1) ascorbic acid (50 micrograms/ml) and sodium beta-glycerophosphate (10 mM), (2) ascorbic acid, sodium beta-glycerophosphate, and dexamethasone (5 microM), or (3) ascorbic acid alone. Cells were then fixed in 2.5% glutaraldehyde, postfixed in 1% OsO4, and prepared for light and electron microscopy. Three-dimensional nodules containing mineralized matrices were formed only when the cells were cultured in the presence of ascorbic acid and dexamethasone. They were composed of multilayered fibroblasts (up to 13 layers), and highly organized collagen fibrils with 64 nm cross-banding patterns between the cell layers. The fibroblasts in the nodules exhibited an elongated shape with a high degree of cytoplasmic polarity throughout the nodule, and have the morphological features of PDL fibroblasts as seen in vivo. Mineral deposition with needle-like crystals was initiated on collagen fibrils located in intercellular spaces of the upper cell layers and became increasingly heavier towards the bottom half of the nodules. X-ray microanalysis and electron diffraction analysis confirmed that mineral deposition contained calcium and phosphate in the form of immature hydroxyapatite.(ABSTRACT TRUNCATED AT 250 WORDS)

Alkaline Phosphatase↗

PubMed1975

Separation and molecular weight estimation of phosphatases in psoriatic scales by disc-electrophoresis.

Disc-electrophoretic investigations of psoriatic scale homogenates (15000 x g supernatant) revealed several different phosphatase activities. At pH 5 either five different phosphatase active bands (substrates: p-nitrophenylphosphate, naphthylphosphate) or three different bands (substrate: glycerophosphate) could be obtained. At pH 7 only one band (substrate: p-nitrophenylphosphate) showed phosphatase activity. At pH 9.9 either two bands (substrate: p-nitrophenylphosphate) or three bands (substrate: glycerophosphate) could be demonstrated. the acid p-nitrophenylphosphatase activity of the psoriatic specific bands "9" and "10" could be distinguished by their different fluoride and tartrate susceptibility. Also the alkaline glycerophosphatase activities could be differentiated by distinct Ca and Mg susceptibility.

Acid Phosphatase↗

PubMed1979

5'-AMP hydrolysis by suspensions and homogenates of pancreatic islet cells from normal and cortisone-treated rats.

Suspensions of endocrine pancreas cells were prepared by shaking collagenase-isolated rat islets of Langerhans in calcium-free buffer. When incubated with 1.0 mM substrate at pH 7.4, the cells split Pi from 5'-AMP at a rate of 87 nmol/h per microgram DNA, and from beta-glycerophosphate at a rate of 25 nmol/h per microgram DNA. Km for 5'-AMP was about 54 microM. Adenosine or theophylline inhibited the 5'-AMP hydrolysis. Homogenization of the cells increased the activity toward 5'-AMP by 23% and that toward beta-glycerophosphate by 115%. Injecting rats with cortisone had no effect on the 5'-AMP hydrolysis by whole cells but significantly increased the activity in cell homogenates; the intracellular activity toward 5'-AMP was more than doubled by the cortisone treatment. Staining whole islet cells for 5'-AMP-splitting activity resulted in a demarcation of the cell periphery in control rats. Cells from cortisone-treated rats showed heavier deposits of reaction product, and their cell periphery did not stand out as clearly. It is suggested that 5'-nucleotidase is largely an ectoenzyme in normal rat islet cells. The cells also contain an as yet unidentified intracellular phosphatase that seems to be solely responsible for the increased hydrolysis of 5'-AMP in cortisone-treated rats.

Adenosine Monophosphate↗

PubMed1984

Oxidations in kidney mitochondria of heat-exposed rats: regulation by cytochrome c.

Exposure of rats to higher environmental temperature (36-37 degrees C) decreased the capacity of their kidney mitochondria to oxidize succinate. The decrease was corrected on the addition of exogenous cytochrome c. Kidney mitochondria of heat-exposed animals showed decreased rates of H2O2 generation when alpha-glycerophosphate, but not succinate, was used as electron donor. These mitochondria also showed decreased activity of alpha-glycerophosphate dehydrogenase but not of succinate dehydrogenase. The content of cytochrome c in kidney mitochondria of heat-exposed animals was low even though the concentration of the pigment in the whole tissue did not decrease. Starvation as well as administration of an antithyroid agent like propylthiouracil simulated some of the effects of heat exposure on kidney mitochondria, but the cytochrome c-dependent reversal of inhibition of oxidation was obtained only in heat exposure.

Animals↗

PubMed2002

Microencapsulation of Aerococcus viridans with catalase and its application for the synthesis of dihydroxyacetone phosphate.

Dihydroxyacetone phosphate is essential for the synthesis of polyhydroxylated compounds used as components or precursors of active pharmaceutical substances, such as antibiotics or glycosidase inhibitors. Dihydroxyacetone phosphate was produced by enzymatic oxidation of L-alpha-glycerophosphate in the presence of glycerophosphate oxidase or Aerococcus viridans coimmobilized with a hydrogen peroxide-decomposing enzyme. The microencapsulation of A. viridans with catalase in sodium alginate showed a conversion of 98.5%; the conversion percentage remained constant in all five runs. Liquid chromatography of the product revealed that the product peak corresponded to that of the dihydroxyacetone phosphate internal standard. This indicated a high degree of product purity.

Alginates↗

PubMed1992

Structural determinants for alcohol substrates to be oxidized to formaldehyde by rat liver microsomes.

Glycerol can be oxidized to formaldehyde by rat liver microsomes and by cytochrome P450. The ability of other alcohols to be oxidized to formaldehyde was determined to evaluate the structural determinants of the alcohol which eventually lead to this production of formaldehyde. Monohydroxylated alcohols such as 1- or 2-propanol did not produce formaldehyde when incubated with NADPH and microsomes. Geminal diols such as 1,3-propanediol, 1,3-butanediol, or 1,4-butanediol also did not yield formaldehyde. However, vicinal diols such as 1,2-propanediol or 1,2-butanediol produced formaldehyde. With 1,2-propanediol, the residual two-carbon fragment was found to be acetaldehyde, while with 1,2-butanediol, the residual three-carbon fragment was propionaldehyde. Oxidation of 1,2-propanediol to formaldehyde plus acetaldehyde involved interaction with an oxidant derived from H2O2 plus nonheme iron, since production of the two aldehydic products was completely prevented by catalase or glutathione plus glutathione peroxidase and by chelators such as desferrioxamine or EDTA. The oxidant was not superoxide or hydroxyl radical. Product formation was fivefold lower when NADH replaced NADPH, and was inhibited by substrates, ligands, and inhibitors of cytochrome P450. A charged glycol such as alpha-glycerophosphate (but not the geminal beta-glycerophosphate) was readily oxidized to formaldehyde, suggesting that interaction of the glycol with the oxidant was occurring in solution and not in a hydrophobic environment. These results indicate that the carbon-carbon bond between 1,2-glycols can be cleaved by an oxidant derived from microsomal generated H2O2 and reduction of non-heme iron, with the subsequent production of formaldehyde plus an aldehyde with one less carbon than the initial glycol substrate.

Acetaldehyde↗

PubMed1976

Respiratory control depression by tetraalkylammonium bromides in rat liver mitochondria.

Six different lipophilic (hydrophobic) organic cations, tetraethyl-, tetrapropyl, tetrabutyl-, tetrapentyl-, tetrahexyl-, and tetraheptylammonium bromide, depressed respiratory control in rat liver mitochondria. Evaluation of mitochondrial responses in terms of a quadratic equation in log P (an index of lipophilicity) indicated that the NADH dehydrogenase receptor site for inhibitor (diminution of control of glutamate, alpha-ketoglutarate, and beta-hydroxybutyrate respiration) was more lipophilic than receptor sites for flavin-linked substrates (reduction of control of succinate, choline and alpha-glycerophosphate respiration). The succinate dehydrogenase receptor site for inhibition by the tetraalkylammonium bromides was more hydrophillic (less lipophilic) than the choline or alpha-glycerophosphate dehydrogenase receptor sites. Depression of respiratory control may be a function of charge density and of lipophilicity at specific inner membranal sites and the susceptible site may differ for different respiratory substrates.

Animals↗

PubMed1986

Absence of substrate channeling in the glycosome of Trypanosoma brucei.

Glycolytic enzymes in the purified glycosomes of Trypanosoma brucei brucei bloodstream forms were crosslinked to form a large protein complex by the bifunctional reagent dimethyl suberimidate [Aman, R.A., Kenyon, G.L. and Wang, C.C. (1985) J. Biol. Chem. 260, 6966-6973]. The crosslinked enzyme complex was found capable of catalyzing the chain reactions leading from glucose to the formation of alpha-glycerophosphate in the presence of ATP and NADH. To determine whether the crosslinked enzyme complex exhibits multiple substrate channelings, these chain reactions were investigated in the crosslinked complex as well as in a preparation of solubilized native glycosomes. When glucose was present at a relatively high concentration (20 mM), production of alpha-glycerophosphate by the crosslinked complex had no apparent lag phase whereas the free enzyme mixture did. However, when the glucose level was lower (0.5-5.0 mM) the difference between the two enzyme preparations disappeared, a lag phase was found in both cases. Formation of sugar phosphates from radiolabeled glucose, followed by high performance liquid chromatographic analysis, showed no significant difference in the diluting powers of exogenous, unlabeled sugar phosphates added to the crosslinked complex or free enzymes. Exogenous fructose 1,6-diphosphatase demonstrated the same effectiveness in disrupting the chain reactions catalyzed by the crosslinked complex and the free enzyme mixture. In situ generation of 2-deoxyglucose-6-phosphate from 2-deoxyglucose and ATP was observed in the crosslinked complex, but the product had no amplified inhibitory effect on the phosphoglucose isomerase activity in the complex. All results suggest an absence of substrate channelings among the glycolytic enzymes in the glycosome of T. b. brucei bloodstream form.

Adenosine Triphosphate↗

PubMed2004

Evidence of downregulation of matrix extracellular phosphoglycoprotein during terminal differentiation in human osteoblasts.

Matrix extracellular phosphoglycoprotein (MEPE) is an extracellular matrix protein that was first detected in tumor-induced osteomalacia (TIO). Investigations in mice revealed that MEPE is expressed in bone and teeth in a maturation-dependent manner, reaching its maximum during mineralization. However, from knockout experiments, although it has become clear that MEPE might function as a mineralization inhibitor, the exact mechanism of action is still unclear. Even less is known about the regulation of MEPE in men. Therefore, we have studied the time- and maturation-dependent expression of MEPE in two human osteoblast culture systems, the osteosarcoma cell line HOS 58 and primary trabecular osteoblasts. Cells were cultured for up to 29 days, and the influence of beta-glycerophosphate (bGP), ascorbate, transforming growth factor beta (TGF-beta), BMP-2, and dexamethasone was studied. HOS 58 cells showed no significant effect on MEPE gene expression up to 5.0 mM, but a significant inhibition was revealed at 10 and 20 mM, when osteocalcin (OC) expression was maximal. Under the same conditions, primary human osteoblasts showed no effect on MEPE gene expression. However, when cultured in the presence of 5 mM beta-glycerophosphate, ascorbate, and dexamethasone for 29 days, which are similar conditions to those described by Owen in his differentiation model in rat osteoblasts, a progressive inhibition of MEPE gene expression to 20% of the maximum was observed. Increasing osteocalcin expression indicated advancing differentiation. In conclusion, in contrast to the results in mice, when MEPE was maximally expressed during mineralization, in the human system, this factor seems to be maximally active in the proliferation and early matrix maturation phase. It was, however, strongly suppressed, associated with the mineralization phase.

Adult↗