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At least 307 records · Page 17Linked to original sources
PubMed1982

Mechanisms of regulation of glycogen phosphorylase activity in Saccharomyces carlsbergensis.

The content of glycogen phosphorylase (1,4-alpha-D-glucan: orthophosphate alpha-D-glycosyl-transferase, EC 2.4.1.1) in yeast (Saccharomyces carlsbergensis) cells depended on the growth phase. Cells of the early exponential phase under carbohydrate-limited conditions showed low, but significant, phosphorylase activity; the activity markedly increased in the late exponential growth phase, concomitant with the appearance of measurable phosphorylase antigen. This pointed to an induction of the enzyme. During the interexponential phase (the slow proliferation phase during the diauxic growth of the culture, when the cells switch to utilization of accumulated ethanol) and the stationary growth phase, phosphorylase concentration remained constant while its specific molecular activity increased further, probably caused by conversion of the enzyme to an active form. During transition of stationary phase cells to growth, phosphorylase activity and concentration slowly decreased in the cells at a rate compatible with dilution by newly synthesized proteins. A residual activity always remained, which could be attributed to the presence of active phosphorylase, detectable by activity staining after gel electrophoresis in the presence of glycogen. No direct correlation could be detected between the specific molecular activity of phosphorylase and glycogen metabolism. This indicated that covalent modification of the enzyme regulated the total capacity of the enzyme available to the cell, rather than the actual activity limiting glycogen breakdown.

Carbohydrate Metabolism↗
PubMed2005

Improvement of ethanol production in very high gravity fermentation by horse gram (Dolichos biflorus) flour supplementation.

AIMS: To determine the effect of osmotic stress on yeast and to investigate the protective role of horse gram flour during very high gravity (VHG) ethanol fermentation. METHODS AND RESULTS: Saccharomyces cerevisiae was inoculated into high sugar (30-40%, w/v) containing medium with and without supplementation of horse gram flour. The fermentation experiments were carried out in batch mode. The effect of 4 or 6% of horse gram flour to the medium on the metabolic behaviour and viability of yeast was studied. Significant increase in ethanol yield up to 50% and dramatic decrease in glycerol production up to 100% was observed in the presence of horse gram flour. The fermentation rate was increased from 3 to 5 days with increased viable cell count. The physical and chemical factors of horse gram flour may aid in reducing the osmotic stress of high gravity fermentation of ethanol as well as enhancing ethanol yield. CONCLUSIONS: It was found that horse gram flour not only reduced fermentation time but also enhanced ethanol production by better utilization of sugar. SIGNIFICANCE AND IMPACT OF THE STUDY: Production of high ethanol concentration by using VHG sugar fermentation eliminates the expensive steps in the conventional process and saves time.

Dolichos↗
PubMed1991

Specific radioimmunoassay to investigate rod outer segment phagocytosis by retinal pigment epithelium in vitro.

A sensitive radioimmunoassay has been developed which allows rapid quantitation of rod outer segment (ROS) phagocytosis by retinal pigment epithelial (RPE) explants in vitro. It involves the use of an antiopsin antiserum, in conjunction with 125I-protein A as a second antibody, and utilizes permeabilization with ethanol to distinguish between the binding and ingestion phases of phagocytosis. This procedure will be used in the future to investigate potential regulatory factors of ROS phagocytosis by retinal pigment epithelium and to evaluate animal models of retinal degeneration.

Animals↗
PubMed2001

Model compound studies: influence of aeration and hemicellulosic sugars on xylitol production by Candida tropicalis.

The influence of other hemicellulosic sugars (arabinose, galactose, mannose, and glucose), oxygen limitation, and initial xylose concentration on the fermentation of xylose to xylitol was investigated using experimental design methodology. Oxygen limitation and initial xylose concentration had strong influences on xylitol production by Candida tropicalis ATCC 96745. Under semiaerobic conditions, xylitol yield was highest (0.62 g/g), whereas under aerobic conditions volumetric productivity was highest (0.90 g/[L x h]). In the presence of glucose, xylose utilization was strongly repressed and sequential sugar utilization was observed. Ethanol produced from the glucose caused a 50% reduction in xylitol yield when the ethanol concentration exceeded 30 g/L. When complex synthetic hemicellulosic sugars were fermented, glucose was initially consumed followed by a simultaneous uptake of the other sugars. The highest xylitol yield (0.84 g/g) and volumetric productivity (0.49 g/[L x h]) were obtained for substrates containing high arabinose and low glucose and mannose contents.

Air↗
PubMed1988

New micro-optical methods to study metabolism in periportal and pericentral regions of the liver lobule.

New techniques employing microlight guides allow metabolic events to be studied noninvasively in tiny volumes of liver tissue located in defined regions within the liver lobule. These events include oxygen utilization, carbohydrate metabolism, ethanol oxidation, monooxygenation, glucaronidation, and sulfation. Two-fiber microlight guides are constructed from 80-microns optical fibers and are placed on periportal or pencentral regions of the liver lobule based on the pattern of liver pigmentation. Light of selected wavelengths is transmitted to the liver surface by one fiber, and the resultant fluorescence or reflectance is delivered to a photomultiplier by the second fiber. The experimental strategy is to monitor native fluors which are metabolically linked (e.g., NADH) or to infuse nonfluorescent substrates which are converted to fluorescent products by specific enzyme systems (e.g., 7-ethoxycoumarin for monooxygenation). Alternatively, disappearance of fluorescence can also be employed (e.g., 7-hydroxycoumarin for sulfation or glucuronidation). With these methods, rate-limiting steps in situ (e.g., substrate uptake, enzyme activity, cofactor supply) have been studied for several metabolic systems in periportal and pericentral regions of the liver lobule.

Animals↗
PubMed1992

Subcloning using simplified adaptor addition.

A simplified procedure for the addition of synthetic oligonucleotide adaptors to subclone DNA fragments with incompatible ends is presented. An organophosphate degradation gene on a PstI fragment was cloned into the HindIII site of the fungal vector pH1S. The opd gene specifies parathion hydrolase and was first isolated from a Flavobacterium sp. The gene was present in 12% of the plasmids recovered and was inserted in either direction with similar frequencies: 53% with the opd start codon distal to the single SalI site of pH1S and 47% in the other orientation. All enzymatic steps were carried out in a single microconcentrator eliminating DNA loss through manipulation and transfer. Normally, during adaptor or linker addition, a larger number of oligonucleotides are attached at each end of the insert DNA and must be removed before cloning. The need for enzymatic digestion to remove excess adaptors was avoided. Traditional methods have utilized phenol/chloroform extraction, ethanol precipitation, gel filtration chromatography, spermine precipitation, or preparative gel electrophoresis. Eliminating these steps resulted in a simpler, more reliable procedure.

Base Sequence↗
PubMed2005

[Construction of flocculation selective vector and expression of beta-glucosidase gene in Saccharomyces cerevisiae].

Selective markers used in yeast vector for gene manipulation were usually drug resistance or autotrophy. Unfortunately, drug resistance selective marker requires drug sensitive host and most industrial strains were not autotrophy. In this paper, flocculation gene (FLO1) from Saccharomyces cerevisiae ABXL-1D was amplified by PCR, sequenced and cloned to construct an expression vector. The new vector was easy to manipulate and suitable for broad host of yeasts without either autotrophy or drugs. beta-glucosidase gene from Bacillus polymyxa was cloned with the vector and expressed in Saccharomyces cerevisiae. The specific activity of beta-glucosidase of the recombinant yeast cell-free extract was 3.91 u/mg protein. The residue glucose of the recombinant yeast was considerably reduced in mixed fermentation of glucose and cellobiose. It should be favorable for ethanol fermentation when utilize lignocellulosic biomass as raw material.

Bacillus↗
PubMedDate not supplied

Effects of chronic ethanol treatment on lipid composition and prostaglandins in rats fed essential fatty acid deficient diets.

Rats of the third generation fed on a diet with 0.3 energy-% (low-essential fatty acids (EFA) or 3 energy-% (normal-EFA) essential fatty acids were given once-daily intraperitoneal injections of ethanol 3 g/kg or isocaloric glucose for 23 days. At the end of the experiment, organs were removed and their weight and lipid composition were determined. The postmortem accumulation of the prostaglandins PGE2, PGF2 alpha and 6-keto-PGF1 alpha was used to assess prostaglandin (PG) precursor availability in the organs. Ethanol was found to amplify the biochemical indicators of EFA-deficiency. The fatty acids 20:3 n-9 in brain phosphatidylethanolamine and phosphatidylinositol and 22:5 n-6 in brain phosphatidylethanolamine and phosphatidylserine were significantly higher in the ethanol group compared to the control group. In the kidney, the 20:3 n-9/20:4 n-6 ratio in phosphatidylinositol and phosphatidylserine was significantly higher in the ethanol group compared to the control group. The low-EFA animals had a lower output of urinary PGF2 alpha than the normal EFA animals. Chronic ethanol treatment gave a pronounced increase of urinary PGF2 alpha in both groups. Kidney levels of PGs were lower in the low EFA-animals. Chronic ethanol treatment gave a further decrease in kidney PGs. PG levels were the same in brains from low-EFA and normal-EFA animals with no effects of ethanol. The data are consistent with an increased utilization of EFA during chronic ethanol intoxication leading to a depletion of PG precursor stores in some but not all organs.

Alcoholism↗
PubMed2003

Effect of acute ethanol administration on S-amino acid metabolism: increased utilization of cysteine for synthesis of taurine rather than glutathione.

Alterations in the hepatic metabolism of S-amino acids were examined in male rats injected with a single dose of ethanol (3 g/kg, i.p.). The hepatic concentrations of methionine and S-adenosylhomocysteine (SAH) were increased, but S-adenosylmethionine (SAM), cysteine, and glutathione (GSH) decreased rapidly following ethanol administration. The activities of methionine adenosyltransferase (MAT), cystathionine beta-synthase (CbetaS) and cystathionine gamma-lyase (CgammaL) were all inhibited. Gamma-glutamylcysteine synthetase (GCS) activity was increased from t = 8 hr, but hepatic glutathione (GSH) level did not return to control for 48 hr. Both hepatic hypotaurine and taurine levels were increased immediately, which were reduced to below control from t = 18 hr. Changes in the serum concentration of taurine were consistent with results observed in the liver. Cysteine dioxygenase (CDO) activity was increased rapidly, but declined from t = 24 hr. The results indicate that an acute dose of ethanol induces significant alterations in the metabolism of S-amino acids in the liver. Ethanol depresses the cysteine availability for GSH synthesis not only by inhibiting the transsulfuration reactions but also by enhancing its irreversible catabolism to taurine via hypotaurine. The physiological significance of this finding is discussed.

Amino Acids, Sulfur↗
PubMed1995

Neurotransmitter interactions in the striatum and hypothalamus of mice after single and repeated ethanol treatment.

In single treatment study, ethanol was administered intraperitoneally to ICR mice (about 34 g) in the amounts of 1.0, 2.0, 3.0 or 4.0 g/kg body weight. The 3,4-dihydroxyphenylacetic acid (DOPAC) + homovanillic acid (HVA) concentration in the striatum was elevated with 3.0 and 4.0 g/kg of ethanol. In the hypothalamus, the DOPAC, HVA and 5-hydroxyindoleacetic acid concentrations were increased after injection of 3.0 and 4.0 g/kg of ethanol. Furthermore, the acetylcholine (ACh) and gamma-aminobutyric acid (GABA) concentrations were also increased following the injection of 1.0, 2.0, 3.0 and 4.0 g/kg. To study the effects of repeated administration, mice were injected intraperitoneally with 1.0 or 2.0 g/kg of ethanol once daily for 7 days. The DOPAC + HVA level in the striatum was elevated after injection of 1.0 and 2.0 g/kg of ethanol. The GABA and ACh concentrations in the hypothalamus were decreased after repeated injections of ethanol. These results suggest that ethanol significantly alters the utilization of dopamine, ACh and GABA in the hypothalamus. This may partially explain why ethanol has such profound effects on emotional behavior and mood.

Animals↗
PubMed1990

Effects of ethanol extraction and duration of heat treatment of soybean flakes on the utilization of soybean protein by growing rats and pigs.

Three experiments were conducted to determine the effects of ethanol extraction and duration of heat treatment of soybean flakes on the utilization of soybean protein by growing rats and pigs. In the first experiment, the treatments were no extraction or extraction with a 55% ethanol-water mixture (v/v), and heat treatments of 0, 5, 10, 20 and 40 min in an autoclave. Ethanol extraction improved rate (P less than .002) and efficiency of gain (P less than .001) of rats. As heat treatment was increased from 0 to 20 min, rate of gain increased, but it decreased again as heating time was increased from 20 to 40 min (P less than .03). In Exp. 2 and 3, 45 pigs were used in a growth assay and 54 were used in a N balance experiment to determine the effects of ethanol extraction on under-, intermediate- and over-processed soybean flakes (i.e., 5, 20 and 60 min of autoclaving). The heat treatments were applied either without, before or after extraction with ethanol. Responses in rate and efficiency of gain to ethanol extraction were greater for soybean flakes heated for either 5 or 60 min than for the soybean flakes heated for 20 min. When pooled across heat treatment, pigs fed the soybean flakes heated before or after extraction with ethanol gained faster (P less than .001), had greater gain:feed (P less than .001) and lower plasma urea concentrations (P less than .002) than pigs fed soybean flakes heated without extraction. Feeding soybean flakes heated and extracted with ethanol also resulted in greater apparent N retention (P less than .003), apparent N digestibility (P less than .001) and apparent biological value (P less than .03) than soybean flakes that were heated without extraction. Ethanol extraction improved the protein quality of soybean flakes, especially when the flakes were under- or overprocessed with heat.

Animals↗
PubMed2006

Kinetics of batch ethanol fermentation of cheese-whey powder (CWP) solution as function of substrate and yeast concentrations.

A lactose utilizing yeast strain, Kluyveromyces marxianus DSMZ-7239 was used for ethanol formation from cheese-whey powder (CWP) solution in batch experiments. Effects of initial substrate (CWP) and yeast concentrations on the rate and extent of ethanol formation were investigated. The initial pH and oxidation-reduction potential (ORP) was kept at 5 and -250 mV, respectively. The rate and extent of ethanol formation increased with increasing CWP concentration up to 156 g l(-1) (75 g l(-1) sugar) and then decreased for larger CWP concentrations due to substrate inhibition at high sugar concentrations. The ethanol yield coefficient was also maximum (0.54 g EtOH/g sugar) and equal to the theoretical yield at CWP concentration of 156 g l(-1). The growth yield coefficient was found to be Y(x/s)=1.2+/-0.1g biomass g sugar(-1). The rate of sugar utilization and ethanol formation also increased linearly with increasing initial biomass concentrations. A kinetic model describing the rate of sugar utilization and substrate inhibition as function of the initial substrate and the biomass concentrations was developed. The kinetic constants were determined using the experimental data. Model predictions of sugar utilization rates were in good agreement with the experimental data. The results indicated that the initial sugar concentration should be below 75 g l(-1) (CWP<156 g l(-1)) and the initial biomass should be above 850 mg l(-1) to obtain high rates and yields of ethanol formation and to avoid substrate inhibition.

Cheese↗
PubMed1973

Utilization of acetate in the human forearm during exercise after ethanol ingestion.

The uptake of acetate in the human forearm was studied in five fasting (14 h) subjects during 10-min periods of ergometer work at 7 and 10 kilopond-meters per minute (kpm/min). A constant arterial acetate concentration was established by administration of a small quantity of alcohol (25 g) to the subjects after a control work period. Blood flow was measured by an indicator dilution technique. Acetate uptake varied linearly with the product of arterial acetate concentration and blood flow. Acetate metabolism was calculated to account for about 6.5% of the energy metabolism, assuming complete combustion to carbon dioxide and water. Oxygen uptake and blood flow did not change in the presence of acetate and ethanol. After administration of ethanol the arterial concentrations of FFA and glycerol decreased to about half, whereas the lactate concentration increased to about twice the control values, confirming other reports. Glucose utilization was increased and lactate output decreased during the ethanol periods, presumably a consequence of the changing arterial concentrations and increased insulin level. Measurements of the arterial and venous lactate/pyruvate concentration ratios indicate that the NAD-mediated cytoplasmic redox state in the muscle is not changed in the presence of acetate and ethanol.

Acetates↗
PubMed1971

Glucose metabolism of embryos and endosperms from deteriorating barley and wheat seeds.

Changes in glucose utilization into CO(2) and ethanol-insoluble material were followed in whole seeds, embryos, and endosperms of wheat (Triticum aestivum L.) and barley (Hordeum vulgare L.) which had reached different levels of deterioration through accelerated aging treatments. Excised embryos from deteriorated wheat seeds had reduced respiration and glucose utilization into ethanol-insoluble material but not into CO(2). These treatments had no effect on respiration of excised endosperms, although they reduced utilization of glucose into ethanol-insoluble material and CO(2). Changes in metabolic activity of whole seeds in response to deterioration treatments are difficult to interpret because they represent the sum of the changes that take place in the embryos and endosperms. Changes in respiration and glucose utilization in these two tissues neither proceed at the same rate nor go in the same direction during deterioration.Incubation of excised embryos and endosperms in glucose-(14)C under N(2), as compared to air, affects the utilization but not the uptake of glucose. Embryos produce more (14)CO(2) and less labeled ethanol-insoluble material under N(2) as compared to air. The responses of endosperms to N(2) are of a much lower magnitude than those of embryos.

Journal Article↗
PubMed1999

Utility of postcolumn addition of 2-(2-methoxyethoxy)ethanol, a signal-enhancing modifier, for metabolite screening with liquid chromatography and negative ion electrospray ionization mass spectrometry.

A strategy for highly sensitive metabolite screening by liquid chromatography-electrospray ionization (ESI) mass spectrometry with the negative-ion mode that involves the use of a reversed-phase column in gradient-elution mode and postcolumn addition of 2-(2-methoxyethoxy)ethanol (2-MEE), a novel signal-enhancing modifier, has been described. When a mobile phase of 50 mM ammonium acetate/acetic acid buffer (pH 4.4) at a flow rate of 100 microL/min was employed, poor ESI response of ibuprofen as a model drug, probably due to both the high surface tension of the mobile phase and the ion-suppression effect of acetate anion in the mobile phase, was observed. On the other hand, the postcolumn addition of 2-MEE (50 microL/min) into the mobile phase counteracted the ion suppression as well as the surface tension problem, resulting in approximately 100-fold signal enhancement of the analyte. The metabolite screening of ibuprofen in human urine was subsequently carried out comparing the results with and without postcolumn addition of 2-MEE. The results indicated that the postcolumn addition of 2-MEE dramatically improved the ESI responses of all urinary metabolites detected without affecting the chromatographic separation.

Anti-Inflammatory Agents, Non-Steroidal↗
PubMed1991

Acute ethanol intoxication suppresses E. coli lipopolysaccharide enhanced glucose utilization by hepatic nonparenchymal cells.

During infection or endotoxemia, the immune system is activated and its energy needs increase. Alcohol (ETOH) intoxication on the other hand suppresses the immune system and increases susceptibility to infection. Since the liver is the primary site both for metabolism of ETOH and detoxification of bacterial lipopolysaccharides (LPS), this investigation was directed at studying the effect of acute ETOH intoxication on the LPS-induced enhancement of in vivo glucose utilization in different types of hepatic cells. Rats were given an intravenous (IV) injection of ETOH followed by a constant infusion for 7 hr to maintain blood alcohol levels at about 175 mg/dl. E. coli LPS was administered IV at 4 hr and in vivo glucose utilization by the different types of liver cells was estimated 3 hr later using the 14C-2-deoxyglucose technique. Hepatocytes (HP), Kupffer (KC), and endothelial cells (EC), as well as the sequestered polymorphonuclear leukocytes (PMN), were separated from the liver by collagenase-pronase digestion followed by centrifugal elutriation and Ficoll-Hypaque density gradient centrifugation. The number of PMN in the liver was increased several-fold 3 hr after LPS administration. The presence of ETOH did not inhibit the LPS-induced neutrophil migration into the liver. ETOH depressed the LPS-induced increase in glucose uptake in both EC and KC by 50 to 80%, respectively. It also reduced the LPS-induced increase of plasma tumor necrosis factor activity by 80%. ETOH alone did not produce any significant changes in the parameters studied.(ABSTRACT TRUNCATED AT 250 WORDS)

Alcoholic Intoxication↗
PubMed2005

Utilization of excess sludge by acetone-butanol-ethanol fermentation employing Clostridium saccharoperbutylacetonicum N1-4 (ATCC 13564).

Clostridium saccharoperbutylacetonicum N1-4 could not grow or produce butanol in excess sludge medium. However, adding glucose to the excess sludge medium resulted in a specific growth rate and butanol productivity of 0.29 h(-1) and 0.55 g/l/h, respectively, and the final butanol production reached 9.3 g/l. Since the content of suspended solids in medium reduced to less than 50% of the initial content during acetone-butanol-ethanol (ABE) fermentation, the sludge was quantitatively decreased by this fermentation employing this strain.

Acetone↗