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PubMed1988

Acute ethanol administration selectively alters localized cerebral glucose metabolism.

The effects of acute ethanol administration on glucose utilization in the CNS of rat were studied using the 2-deoxyglucose technique. Cerebral glucose utilization was determined for 53 brain regions at peak and descending blood ethanol concentrations averaging 14, 26 and 66 mM. Decreased glucose utilization was the predominant finding and was observed in 20% of the regions evaluated, with median raphe, vestibular nucleus, cerebellar vermis, and various structures associated with the auditory system showing the greatest reductions. The only structures that showed increased glucose utilization were the dentate region of the hippocampus and the superior olive, and this was only apparent at a blood ethanol concentration of 14 mM.

Animals↗
PubMedDate not supplied

Interaction between hydroquinone and ascorbic acid derivatives: quenching effect of organic solvents.

The interaction between hydroquinone (HQ) and ascorbic acid analogs was investigated. Semiquinone radicals (SQ.) generated by HQ were comparably scavenged by ascorbic acid, sodium ascorbate and ascorbate 6-palmitate, but much less efficiently by ascorbate 2,6-dipalmitate. Organic solvents, such as dimethysulfoxide (DMSO) or ethanol, which are utilized for solubilization of water-insoluble analogs, ascorbate 6-palmitate and ascorbate 2,6-dipalmitate, also scavenged SQ.. DMSO scavenged the SQ. more efficiently than ethanol. This suggests the importance of considering such a quenching effect of organic solvent in the study of the interaction between HQ and antioxidants. The involvement of the ascorbate radical for cytotoxicity induction is discussed.

Ascorbic Acid↗
PubMed1980

[Effects of soluble carbohydrates from several tropical foods (cassava, peanuts, coconut and papaya) on calcium utilization in the rat].

Ethanolic extracts containing soluble sugars were prepared from four foods : cassava, peanut, coconut and papaye. Six-month-old rats were given by stomach tube 10 mM CaCl2 solution (+ 45Ca) containing a carbohydrate. Depending on the group, the carbohydrate was glucose or melibiose or raffinose at 200 mM concentration, or one ethanolic extract. Blood samples were taken at different times after the administration and plasma radioactivity was measured. Rats were sacrificed at 24 hours; femur radioactivity was used as a measure of calcium absorption. Extracts of cassava, peanut, and papaye were the more patent in promoting calcium absorption. Extracts of coconut were less effective. This physiological activity of the extracts was correlated with the nature of sugars, identified by paper chromatography. Cassava contained raffinose, peanut included fructose, raffinose and stachyose. Fructose was abundant in papaye but in little quantity in coconut. The present experiments or earlier works had showed that these sugars enhanced calcium utilization.

Animals↗
PubMed2003

[Progress in the pathway engineering of ethanol fermentation from xylose utilising recombinant Saccharomyces cerevisiae].

Pathway engineering was the third generation of gene engineering. Its main goals were to change metabolic flux and open a new metabolic pathway in organism. Application of recombinant DNA methods to restructure metabolic networks can improve production of metabolite and protein products by altering pathway distributions and rates. Ethanol is the most advanced liquid fuel because it is environmentally friendly. Enhancing fuel ethanol production will require developing lower-cost feedstock, and only lignocellulosic feedstock is available in sufficient quantities to substitute for corn starch. Xylose is the major pentose found in lignocellulosic materials and after glucose the most abundant sugar available in nature. Recently a lot of attentions have been focused on designing metabolic pathway of Saccharomyces cerevisiae in order to expand the substrate of ethanol fermentation, because it is a traditional ethanol producing strain and has wonderful properties for ethanol industry. However, it can not utilize xylose but convert the isomer, xylulose. Many attempts are based on introducing the genes in the pathway of xylose metabolism. The further research includes overexpressing the key enzyme or decreasing the unimportant flux. The sugars in lignocellulose hydrolyzates, therefore, could be efficiently utilized. Here, we describe the ethanol pathway engineering progress in ethanol fermentation from xylose with recombinant Saccharomyces cerevisiae.

Biotechnology↗
PubMed2004

Biotechnological processes for conversion of corn into ethanol.

Ethanol has been utilized as a fuel source in the United States since the turn of the century. However, it has repeatedly faced significant commercial viability obstacles relative to petroleum. Renewed interest exists in ethanol as a fuel source today owing to its positive impact on rural America, the environment and United States energy security. Today, most fuel ethanol is produced by either the dry grind or the wet mill process. Current technologies allow for 2.5 gallons (wet mill process) to 2.8 gallons (dry grind process) of ethanol (1 gallon = 3.785 l) per bushel of corn. Valuable co-products, distillers dried grains with solubles (dry grind) and corn gluten meal and feed (wet mill), are also generated in the production of ethanol. While current supplies are generated from both processes, the majority of the growth in the industry is from dry grind plant construction in rural communities across the corn belt. While fuel ethanol production is an energy-efficient process today, additional research is occurring to improve its long-term economic viability. Three of the most significant areas of research are in the production of hybrids with a higher starch content or a higher extractable starch content, in the conversion of the corn kernel fiber fraction to ethanol, and in the identification and development of new and higher-value co-products.

Biotechnology↗
PubMed1992

Ethanol dependence and withdrawal selectively alter localized cerebral glucose utilization.

The 2-deoxyglucose technique was used to determine local cerebral glucose utilization (LCGU) in over 50 brain regions of rats physically dependent upon ethanol and compared to those of acutely intoxicated and those undergoing an overt ethanol-withdrawal syndrome. Dependent-intoxicated rats (average blood ethanol concentration 64 mM) had decreased LCGU in 13/54 regions, including those associated with the limbic system, cerebellum, and motor system. The ethanol withdrawal syndrome was associated with 17/50 gray regions showing an increase, including regions involved with motor function, auditory system, and mammillary bodies-anterior thalamus-cingulate cortex pathway. The most pronounced differences between these groups occurred in regions associated with motor function, cerebellar function, anterior thalamus, and median raphe. Comparisons between dependent-intoxicated and acutely intoxicated rats (average blood ethanol concentration 66 mM) revealed that acute intoxication was associated with a relatively greater reduction in LCGU in regions involved with sensory-related functions, mammillary bodies, and median raphe. With the development of dependence, adaptation occurred in these regions except for inferior colliculus and median raphe. Dependence was also associated with a relative decrease in LCGU in white matter, limbic system, and extrapyramidal motor system.

Animals↗
PubMed1997

Biological conversion of lignocellulosic biomass to ethanol.

The important key technologies required for the successful biological conversion of lignocellulosic biomass to ethanol have been extensively reviewed. The biological process of ethanol fuel production utilizing lignocellulose as substrate requires: (1) delignification to liberate cellulose and hemicellulose from their complex with lignin, (2) depolymerization of the carbohydrate polymers (cellulose and hemicellulose) to produce free sugars, and (3) fermentation of mixed hexose and pentose sugars to produce ethanol. The development of the feasible biological delignification process should be possible if lignin-degrading microorganisms, their echophysiological requirements, and optimal bioreactor design are effectively coordinated. Some thermophilic anaerobes and recently-developed recombinant bacteria have advantageous features for direct microbial conversion of cellulose to ethanol, i.e. the simultaneous depolymerization of cellulosic carbohydrate polymers with ethanol production. The new fermentation technology converting xylose to ethanol needs also to be developed to make the overall conversion process more cost-effective. The bioconversion process of lignocellulosics to ethanol could be successfully developed and optimized by aggressively applying the related novel science and technologies to solve the known key problems of conversion process.

Biomass↗
PubMed1997

Study on the hydrolyzate of sugarcane bagasse to ethanol by fermentation.

Study of glucose and xylose utilization by Pichia stipitis in a limited oxygen supply condition revealed that the rate of glucose utilization decreased rapidly while that of xylose decreased slowly until the time that glucose and xylose were shown to level out, at which point the rate of xylose utilization increased rapidly. Based on the results, ethanol fermentation technology in continuous connective tower fermenters was advanced, e.g., fermentation by P. stipitis in an airlift loop tower focusing on xylose utilization and then residue glucose utilization by Saccharomyces cerevisiae in an overflow tower. When the fed hydrolyzate of bagasse was concentrated in five folds and the dilution rate was 0.1 h-1, the total utilization ratio of reducing sugar was 97.2%; the concentration of ethanol was 46.4 g/L.h.

Cellulose↗
PubMed1984

Paper pulpmill sludge utilization: techno-economic potential for fuel ethanol, methane and scp production.

Various processes have been developed or proposed for converting cellulosic residues from pulp and paper mills into products which can be used for fuel or food. Among the promising practical possibilities are processes for ethanol, methane and microbial protein production by fermentation technology. Given the current Canadian financial climate and product demand, the results of techno-economic sensitivity analyses of these three process options indicate that microbial protein production for animal food applications is the most attractive followed by methane then ethanol, the last being quite uneconomical at present. Ironically, research emphasis seems to be placed in the reverse order. It is evident that the relevant costs of upstream and downstream processing in the various process proposals have not been adequately addressed. Case studies of several scenarios illustrate the problems.

Journal Article↗
PubMed1972

Utilization and metabolic effects of acetaldehyde and ethanol in the perfused rat liver.

1. Removal of acetaldehyde and ethanol has been studied in perfused rat livers. 2. The maximum rate of ethanol oxidation was 2mumol/min per g of liver, which was less than the calculated capacity of the ethanol-oxidizing system. The lactate/pyruvate ratio of the medium increased with the rate of ethanol removal. At low ethanol concentrations most of the acetaldehyde formed was oxidized further, but at ethanol concentrations above 16mm about 60% of the acetaldehyde left the liver unmetabolized. 3. At lower concentrations the greater part of added acetaldehyde was oxidized, but above 5mm, 50-60% of that removed was recovered as ethanol. 4. When the reduction of acetaldehyde was blocked by pyrazole, removal was strongly diminished. There was no effect on the lactate/pyruvate ratio during oxidation of low concentrations of acetaldehyde, even in the presence of pyrazole, but at higher concentrations a gradual increase occurred. 5. The results indicate that during ethanol oxidation the ethanol/acetaldehyde pair is not in redox equilibrium with the lactate/pyruvate pair. Ethanol oxidation was abolished by addition of acetaldehyde. Under these conditions the lactate/pyruvate ratio was 1.5-1.8 times the ethanol/acetaldehyde ratio, indicating equilibration of the alcohol dehydrogenase and lactate dehydrogenase systems. 6. The results support the view that ultimately the rate of mitochondrial oxidation of NADH limits the removal of ethanol in the liver.

Acetaldehyde↗
PubMed1986

The effect of ethanol on the production of lactate, triglycerides, phospholipids, and free fatty acids in the perfused human placenta.

Eighteen fresh term placentas from normal deliveries were perfused to determine the biochemical response of the human placenta in the absence and presence of ethanol. The production rates were generally increased by ethanol administration; lactate, 22%; triglycerides, 49%; sphingomyelin, 362%; lecithin, 67%; lipid phosphorus, 780%; free fatty acids, 897%. Only the changes in lipid phosphorus and free fatty acids were significantly different (p less than 0.05). Glucose utilization rates were 600 and 551 mg per hour per placenta for eight control and 10 ethanol runs, respectively. The ethanol utilization rate was 442 mg per hour per placenta. Little difference in ultrastructural appearance between control and ethanol groups was observed at the level of ethanol administered. The general behavior of ethanol metabolism in human placenta seems qualitatively similar to that in the liver.

Ethanol↗
PubMed1975

Metabolic studies on the development of ethanol-induced fatty liver in KK-Ay mice.

Mechanisms involved in the development of the alcoholic fatty liver in KK-Ay mice were investigated. Incorporation studies using [14C]acetate and [3H]palmitate indicated that the half-life of hepatic triglycerides was doubled in the ethanol-ingesting mice, and utilization of the exogenous fat was significantly increases as compared with that of the control. No persistent alteration was recognized in hepatic oxidation of palmitate, as estimated by in vitro experiments using liver slices obtained from control and ethanol-drinking mice. Enzymic studies indicated that the activities of acetyl COA carboxylase, ATP citrate lyase, malic enzyme, and 6-phosphogluconate dehydrogenase were increased with ethanol drinking. The increment in hepatic triglycerides accumulated during ethanol ingestion was largely accounted for by palmitoleic, oleic, and linoleic acids. These findings demonstrated an augmentation in hepatic lipogenesis as well as an increased utilization of exogenous fats. Ethanol drinking did not cause any appreciable change in plasma triglyceride level and metabolism of adipose tissue. In summary of the present studies, accelerated lipogenesis and increased utilization of the dietary fats may be possible causal factors in the alcoholic fatty liver of KK-Ay mice.

ATP Citrate (pro-S)-Lyase↗
PubMed2001

Xylulokinase overexpression in two strains of Saccharomyces cerevisiae also expressing xylose reductase and xylitol dehydrogenase and its effect on fermentation of xylose and lignocellulosic hydrolysate.

Fermentation of the pentose sugar xylose to ethanol in lignocellulosic biomass would make bioethanol production economically more competitive. Saccharomyces cerevisiae, an efficient ethanol producer, can utilize xylose only when expressing the heterologous genes XYL1 (xylose reductase) and XYL2 (xylitol dehydrogenase). Xylose reductase and xylitol dehydrogenase convert xylose to its isomer xylulose. The gene XKS1 encodes the xylulose-phosphorylating enzyme xylulokinase. In this study, we determined the effect of XKS1 overexpression on two different S. cerevisiae host strains, H158 and CEN.PK, also expressing XYL1 and XYL2. H158 has been previously used as a host strain for the construction of recombinant xylose-utilizing S. cerevisiae strains. CEN.PK is a new strain specifically developed to serve as a host strain for the development of metabolic engineering strategies. Fermentation was carried out in defined and complex media containing a hexose and pentose sugar mixture or a birch wood lignocellulosic hydrolysate. XKS1 overexpression increased the ethanol yield by a factor of 2 and reduced the xylitol yield by 70 to 100% and the final acetate concentrations by 50 to 100%. However, XKS1 overexpression reduced the total xylose consumption by half for CEN.PK and to as little as one-fifth for H158. Yeast extract and peptone partly restored sugar consumption in hydrolysate medium. CEN.PK consumed more xylose but produced more xylitol than H158 and thus gave lower ethanol yields on consumed xylose. The results demonstrate that strain background and modulation of XKS1 expression are important for generating an efficient xylose-fermenting recombinant strain of S. cerevisiae.

Aldehyde Reductase↗
PubMed2002

Kinetic model for nitrogen-limited wine fermentations.

A physical and mathematical model for wine fermentation kinetics has been developed to predict sugar utilization curves based on experimental data from wine fermentations with various initial nitrogen and sugar concentrations in the juice. The model is based on: (1) yeast cell growth limited by nitrogen; (2) sugar utilization rates and ethanol production rates proportional solely to the number of viable cells; and (3) a death rate for cells proportional to alcohol content. All but one parameter in the model can be estimated from existing data. However, experiments to find this final parameter, a constant describing cell death, indicate that cell death may not be the critical factor in determining fermentation kinetics as cell viability remains significant until sugar utilization has ceased. The model, nevertheless, predicts a transition from normal to sluggish to stuck fermentations as initial nitrogen levels decrease. It also predicts that fermentations with high initial Brix levels may go to completion when supplemented with nitrogen in the form of ammonia. Therefore, we hypothesize that the model is valid but that ethanol causes the yeast cells to become inactive while remaining viable. Experimental verification of the model has been performed using flask-scale experiments. The model has also been used to evaluate the possibility of using nitrogen or viable cell additions to avoid or correct problem (i.e., sluggish or stuck) fermentations.

Carbohydrate Metabolism↗
PubMed1987

Increased sensitivity of the microsomal oxidation of ethanol to inhibition by pyrazole and 4-methylpyrazole after chronic ethanol treatment.

Pyrazole and 4-methylpyrazole, inhibitors of the oxidation of ethanol by alcohol dehydrogenase, also inhibit microsomal metabolism of ethanol. The inhibitory effectiveness of these agents was increased in microsomes isolated from rats treated chronically with ethanol as compared to microsomes from pair-fed controls or from rats treated with other cytochrome P-450 inducers such as phenobarbital or 3-methylcholanthrene. Pyrazole and 4-methylpyrazole produced type II binding spectra with all the microsomal preparations. However, there was an increased affinity (lower Ks value) for these agents by the microsomes from the ethanol-fed rats. A correlation between Ks values and inhibitory effectiveness against ethanol oxidation by the various microsomal preparations could be observed. This suggests that an increase in affinity, which may reflect the induction of an alcohol-preferring isozyme of cytochrome P-450, is responsible for the increased inhibitory effectiveness of pyrazole and 4-methylpyrazole towards ethanol oxidation by microsomes after chronic ethanol treatment. One difference between pyrazole and 4-methylpyrazole was the increased affinity and inhibitory effectiveness of the latter but not the former with microsomes from rats treated with 3-methylcholanthrene. This could be due to the ability of 4-methylpyrazole, compared to pyrazole, to interact with and induce several isozymes of cytochrome P-450. Pyrazole and 4-methylpyrazole are often utilized to evaluate ethanol metabolism by alcohol-dehydrogenase-dependent and -independent pathways. However, the sensitivity of microsomal ethanol oxidation to inhibition by these agents, especially after chronic ethanol treatment, would suggest that their use in this regard is complex and could tend to underestimate the contribution of the microsomal pathway towards the metabolic tolerance found after ethanol treatment.

Animals↗
PubMed1994

Distorted microangioarchitecture and impaired angiogenesis in gastric mucosa of portal hypertensive rats.

BACKGROUND/AIMS: Portal hypertensive (PHT) gastropathy is now recognized as a distinct entity, but the size of microvessels has been a subject of controversy. Angiogenesis in PHT gastric mucosa has not been explored. The aim of this study was to examine the angioarchitecture of PHT and non-PHT gastric mucosae before and after ethanol-induced injury utilizing microvascular cast techniques. METHODS: Portal hypertension was produced by staged portal vein occlusion. Fourteen days later, gastric vascular casts were made in both PHT and control (sham-operated) rats by Mercox resin infusion. After tissue dissolution, casts were examined under a scanning electron microscope. To examine angiogenesis in injured gastric mucosa, the above study was repeated in PHT and control rats 18 hours after intragastric administration of 100% ethanol. RESULTS: The capillary casts in PHT gastric mucosa (mean diameter, 6.3 +/- 0.03 microns) were significantly narrower than those of controls (mean diameter, 8.6 +/- 0.02 microns; P < 0.01). After ethanol injury, 5.5% +/- 0.3% of microvessels in gastric mucosa of sham-operated rats contained buds, showing angiogenesis. In contrast, PHT gastric mucosa had a paucity of capillary angiogenesis (buds in only 0.4% +/- 0.2% of microvessels; P < 0.01 vs. control). CONCLUSIONS: This study shows prominent persistent abnormalities in the microangioarchitecture of PHT gastric mucosa. Moreover, PHT gastric mucosal microvessels have a marked impairment of angiogenic response to ethanol injury.

Animals↗
PubMed1983

Value of cuticular and internal hydrocarbons for the identification of larvae of Anopheles gambiae Giles, Anopheles arabiensis Patton and Anopheles melas Theobald.

Gas chromatographic profiles of the cuticular and internal lipids extracted from 4th-instar larvae of the Anopheles gambiae complex have shown quantitative differences in their chain length distributions. For example, hydrocarbons extracted with 95% ethanol showed relative differences in peak heights eluting at Kovat indices (KI's) 2840 (An. gambiae 1.21, An. arabiensis 1.39 and An. melas 1.14) and 3150 (An. gambiae 6.73, An. arabiensis 13.40 and An. melas 13.50). However, while using the non-hydrocarbon fractions, differences were obtained at a KI of 2160 (An. gambiae 0.45, An. arabiensis 0.45 and An. melas 1.16) and at a KI of 2430 (An. gambiae 2.90, An. arabiensis 1.81 and An. melas 3.50). Utilizing the total ethanol extract and omitting the TLC (thin layer chromatography) step, thus saving four hours of analysis time, good separation was achieved at a KI of 2060 (An. gambiae 0.60, An. arabiensis and An. melas 0.0) and at a KI of 2430 (An. gambiae 1.13, An. arabiensis 0.69 and An. melas 1.59). Other differences were also noted in the profiles which could identify one or more of the three species. Good separation could be made on single larvae as well as on small batches of specimens. It was concluded that analysis of cuticular and internal lipids provides a useful biochemical method of distinguishing larvae of these species, but further studies are needed on these and other species of the An. gambiae complex collected from many localities in Africa.

Animals↗
PubMed2004

Effect of pH on cellulase production of Trichoderma reesei RUT C30.

Currently, the high market price of cellulases prohibits commercialization of the lignocellulosics-to-fuel ethanol process, which utilizes enzymes for saccharification of cellulose. For this reason research aimed at understanding and improving cellulase production is still a hot topic in cellulase research. Trichoderma reesei RUT C30 is known to be one of the best hyper producing cellulolytic fungi, which makes it an ideal test organism for research. New findings could be adopted for industrial strains in the hope of improving enzyme yields, which in turn may result in lower market price of cellulases, thus making fuel ethanol more cost competitive with fossil fuels. Being one of the factors affecting the growth and cellulase production of T. reesei, the pH of cultivation is of major interest. In the present work, numerous pH-controlling strategies were compared both in shake-flask cultures and in a fermentor. Application of various buffer systems in shake-flask experiments was also tested. Although application of buffers resulted in slightly lower cellulase activity than that obtained in non-buffered medium, beta-glucosidase production was increased greatly.

Biotechnology↗