Development of nanostructured bioanodes containing dendrimers and dehydrogenases enzymes for application in ethanol biofuel cells

This paper describes the use of the electrostatic layer-by-layer (LbL) technique for the preparation of bioanodes with potential application in ethanol/O(2) biofuel cells. More specifically, the LbL technique was employed for immobilization of dehydrogenase enzymes and polyamidoamine (PAMAM) dendrimers onto carbon paper support. Both mono (anchoring only the enzyme alcohol dehydrogenase, ADH) and bienzymatic (anchoring both ADH and aldehyde dehydrogenase, AldDH) systems were tested. The amount of ADH deposited onto the Toray (R) paper was 95 ng cm(-2) per bilayer. Kinetic studies revealed that the LbL technique enables better control of enzyme disposition on the bioanode, as compared with the results obtained with the bioanodes prepared by the passive adsorption technique. The power density values achieved for the mono-enzymatic system as a function of the enzyme load ranged from 0.02 to 0.063 mW cm(-2) for the bioanode containing 36 ADH bilayers. The bioanodes containing a gas diffusion layer (GDL) displayed enhanced performance, but their mechanical stability must be improved. The bienzymatic system generated a power density of 0.12 mW cm(-2). In conclusion, the LbL technique is a very attractive approach for enzyme immobilization onto carbon platform, since it enables strict control of enzyme disposition on the bioanode surface with very low enzyme consumption. (C) 2010 Elsevier B.V. All rights reserved.

Development of novel bioanodes for ethanol biofuel cell using PAMAM dendrimers as matrix for enzyme immobilization

This paper describes the preparation and application of a novel bioanode for use in ethanol/O(2) biofuel cells based upon immobilization of alcohol dehydrogenase (ADH) and polyamidoamine (PAMAM) dendrimers onto carbon cloth platforms. The power density measurements indicated a direct relationship between the amount of anchored ADH and the anode power values, which increased upon enzyme loading. The power density values ranged from 0.04 to 0.28 mW cm(-2), and the highest power density was achieved with the bioanode prepared with 28 U of ADH, which provided a power density of 0.28 mW cm(-2) at 0.3 V. The latter power output values were the maximum observed, even for higher enzyme concentrations. Stability of the bioanodes was quite satisfactory, since there was no appreciable reduction of enzymatic activity during the measurements. The method of bioanode preparation described here has proven to be very effective. The PAMAM dendrimer represents a friendly environment for the immobilization of enzymes, and it is stable and capable of generating high power density compared to other immobilization methods. (C) 2010 Elsevier B.V. All rights reserved.

Sucrose Fermentation by Brazilian Ethanol Production Yeasts in Media Containing Structurally Complex Nitrogen Sources

Four Saccharomyces cerevisiae Brazilian industrial ethanol production strains were grown, under shaken and static conditions, in media containing 22% (w/v) sucrose supplemented with nitrogen sources varying from a single ammonium salt (ammonium sulfate) to free amino acids (casamino acids) and peptides (peptone). Sucrose fermentations by Brazilian industrial ethanol production yeasts strains were strongly affected by both the structural complexity of the nitrogen source and the availability of oxygen. Data suggest that yeast strains vary in their response to the nitrogen source`s complex structure and to oxygen availability. In addition, the amount of trehalose produced could be correlated with the fermentation performance of the different yeasts, suggesting that efficient fuel ethanol production depends on finding conditions which are appropriate for a particular strain, considering demand and dependence on available nitrogen sources in the fermentation medium.

Ethanol feeding enhances inflammatory cytokine expression in lipopolysaccharide-induced hepatitis

Elevated concentrations of plasma tumour necrosis factor (TNF)-alpha, interleukin (IL)-1 and IL-6 have been detected in patients with alcoholic hepatitis and have been implicated in the pathogenesis of hepatocyte necrosis. The present study used a rat model to conduct a detailed histological and biochemical examination of the expression of various pro-inflammatory cytokines and associated liver pathology in ethanol-potentiated lipopolysaccharide (LPS)-induced liver injury. Male Wistar rats were pair-fed either the control or ethanol-containing (36% of caloric intake as ethanol) form of the Lieber-DeCarli liquid diet for 6 weeks. Liver injury was induced by the i.v. injection of LPS (1 mu g/g bodyweight), with animals being killed at O, 1, 3, 6, 12 and 24 h after injection. At the later time points, plasma transaminase and transpeptidase activities were significantly elevated in ethanol-fed LPS-treated rats compared with control-fed LPS-treated animals. At these times after LPS treatment, hepatocytes in ethanol-fed animals displayed fatty change and necrosis with an associated neutrophil polymorph infiltrate. Time course analysis revealed that plasma TNF-alpha (1-3 h post-LPS) and IL-6 (3 h post-LPS) bioactivity was significantly elevated in ethanol-fed compared with control-fed animals. No difference was seen in plasma IL-1 alpha concentration (maximal in both groups 6 h post-LPS). The expression of TNF-alpha, IL-1 alpha, IL-1 beta and IL-6 mRNA were elevated between 1 and 6 h post-LPS in the livers of both control and ethanol-fed rats. However, ethanol-fed LPS-treated animals exhibited significantly higher maximal expression of IL-1 and IL-6 mRNA. Comparison of the appearance of cytokine mRNA and plasma bioactivity indicated an effect of ethanol feeding on post-transcriptional processing and/or the kinetics of the circulating cytokines. Elevated levels of both hepatic cytokine mRNA expression and the preceding plasma cytokines are presumably a necessary prerequisite for hepatic injury seen in this model and, therefore, possibly for the damage seen in human alcoholics. Further studies using this model may lead to significant advances in our understanding of the pathogenic mechanisms of alcoholic liver disease in humans.

AP-1 and Egr DNA-binding activities are increased in rat brain during ethanol withdrawal

The DNA-binding activities of AP-1 and Egr proteins were investigated in nuclear extracts of rat brain regions during ethanol withdrawal. Both DNA-binding activities were transiently elevated in the hippocampus and cerebellum 16 h after withdrawal. In the cerebral cortex, AP-1 and Egr DNA-binding activities increased at 16 h and persisted until 32 and 72 h, respectively. The AP-1 DNA-binding activities in all regions at all times after withdrawal were composed of FosB, c-Jun, JunB, and JunD. c-Fos was detected at all times in the cerebral cortex, at 16 h only in the hippocampus, and from 16 to 72 h in the cerebellum. Withdrawal severity did not affect the composition of the AP-1 DNA-binding activities. Two Egr DNA-binding activities were present in the cortex and hippocampus. The faster-migrating complex predominated in hippocampus, and only the slower-migrating complex (identified as Egr-1) was present in the cerebellum. The increase in DNA-binding activity of immediate early gene-encoded transcription factors supports their proposed role in initiating a cascade of altered gene expression underlying the long-term neuronal response to ethanol withdrawal.

Self-defocusing effects in an ethanol solution of chlorophyll

The thermally induced optical nonlinearity in a chlorophyll ethanol solution is examined. A theory is presented which shows good agreement with experiment. The theory models an optically thick but physically thin medium whose only heat transport mechanism is conduction. An average nz was found for the medium which corresponds well with previous results but the thermal medium is shown to be fundamentally different from a Kerr medium.

Differential expression of mitochondrial NADH dehydrogenase in ethanol-treated rat brain: Revealed by differential display

The technique of polymerase chain reaction (PCR) differential display was used to detect alterations in gene expression after chronic alcohol administration. Male Wistar rats were treated with ethanol vapor for 14 days. The cDNA generated from mRNA isolated from the hippocampi of ethanol-treated and control animals was compared by PCR differential display. A differentially expressed cDNA fragment was used to screen mRNA samples by Northern analysis. The level of a mRNA was significantly elevated (x 2.5) in the hippocampus, but not the cortex of alcohol-treated rats up to 48 hr after withdrawal. Sequence analysis of the cDNA fragment revealed an almost perfect homology to rat mitochondrial NADH dehydrogenase subunit 4 mRNA. The selective induction of this mRNA in alcohol-treated rat brain areas suggests altered metabolic processes and possible dysfunction of the mitochondria. The technique of PCR differential display may prove useful in further analysis of gene expression during alcohol dependence and withdrawal.

Spatial learning ability of rats following differing levels of exposure to alcohol during early postnatal life

Rats exposed to a relatively high dose (7.5 g/kg body weight) of alcohol on either the fifth or tenth postnatal day of age have been reported to have long-lasting deficits in spatial learning ability as tested on the Morris water maze task. The question arises concerning the level of alcohol required to achieve this effect. Wistar rats were exposed to either 2, 4 or 6 g/kg body weight of ethanol administered as a 10% solution. This ethanol was given over an 8-h period on the fifth postnatal day of age by means of an intragastric cannula. Gastrostomy controls received a 5% sucrose solution substituted isocalorically for the ethanol. Another set of pups raised by their mother were used as suckle controls. All surgical procedures were carried out under halothane vapour anaesthesia. After the artificial feeding regimes all pups were returned to lactating dams and weaned at 21 days of age. The spatial learning ability of these rats was tested in the Morris water maze when they were between 61-64 days of age. This task requires the rats to swim in a pool containing water made opaque and locate and climb onto a submerged platform. The time taken to accomplish this is known as the escape latency. Each rat was subjected to 24 trials over 3 days of the test period. Statistical analysis of the escape latency data revealed that the rats given 6 g/kg body weight of ethanol had significant deficits in their spatial learning ability compared with their control groups. However, there was no significant difference in spatial learning ability for the rats given either 2 or 4 g/kg body weight of ethanol compared with their respective gastrostomy or suckle control animals. We concluded that ethanol exposure greater than 4 g/kg over an 8-h period to 5-day-old rats is required for them to develop long-term deficits in spatial learning behaviour. (C) 1998 Elsevier Science Inc.

Synergistic effect of ethanol and mitomycin C on corneal stroma

PURPOSE: To investigate the combined effects of ethanol and mitomycin C (MMC) application on the corneal stroma of rabbits that underwent photorefractive keratectomy (PRK). METHODS: Twenty-four rabbits (24 eyes) underwent PRK to correct -9.00 diopters of myopia. Twelve eyes had ethanol application before removing the epithelium and 12 eyes had the epithelium manually removed without ethanol, Eyes in both groups had topical MMC 0.02% application for 12 seconds immediately after excimer laser ablation. Twelve rabbits were sacrificed at two time points-4 hours and 4 weeks after surgery-and immunohistochemistry was performed with TUNEL assay, alpha-smooth muscle actin (alpha-SMA), and DAPI. RESULTS: More TUNEL-positive cells were observed in the ethanol-treated group compared to the mechanical debridement group at 4 hours after surgery (P<.01). No significant difference in alpha-SMA-positive cells was detected, between the two groups at 4 weeks after sugery. However, decreased keratocyte density in the anterior stroma was more pronounced in the ethanol-treated group compared to the mechanical debridement (P<.02). CONCLUSIONS: Ethanol application for epithelial removal during PRK seems to produce a synergistic effect with MMC, resulting in fewer keratocytes in the anterior stroma of rabbit corneas treated with MMC and ethanol than in corneas treated with MMC alone after PRK.

Dietary habits, ethanol and tobacco consumption as predictive factors in the development of esophageal carcinoma in patients with head and neck neoplasms

Patients with primary head and neck cancers have a higher risk of developing esophageal cancer. The aim of this study was to investigate esophageal cancer prevalence, its risk factors (ethanol and tobacco consumption) and dietary habits in patients with head and neck cancer. Three hundred and twenty-six adults with primary head and neck cancer were followed by a retrospective observational study in a general university hospital in Sao Paulo, Brazil. Flexible videoendoscopy with lugol chromoscopy was the method used to investigate esophageal cancer prevalence. All subjects were interviewed face-to-face, revealing detailed information about their tobacco and alcohol use, as well as their dietary habits. Thirty-six patients with esophageal cancer were diagnosed and the overall prevalence rate was 11.04%. Patients who developed second esophageal tumors had the following characteristics: earlier age of initial ethanol consumption (P < 0.05), longer duration period of ethanol consumption (P < 0.05) and higher weekly consumption rate (P < 0.05). There was an increased risk of esophageal carcinoma in those patients who both smoked and drank (P < 0.05). There was no association between carcinoma of the esophagus and dietary habits in patients who developed esophageal neoplasms, compared with those who did not. Prevalence rate of esophageal neoplasms was 11.04% in patients with head and neck carcinoma, whose ethanol consumption was associated with esophageal cancer. There was an increased risk between ethanol and tobacco consumption and esophageal carcinoma development. On the other hand, there was no association regarding dietary habits between patients who developed esophageal cancer and those who did not.

Haze Development After Photorefractive Keratectomy: Mechanical vs Ethanol Epithelial Removal in Rabbits

PURPOSE: To compare mechanical and ethanol epithelial removal with respect to myofibroblast development and haze formation after photorefractive keratectomy (PRK). METHODS: Seventeen rabbits underwent mechanical or ethanol debridement, and the opposite eye of each rabbit served as an unwounded control. In both groups, the epithelium was removed with a spatula and discarded. A -9.00-diopter PRK was performed in each eye. The level of haze in each cornea at 4 weeks was graded at the slit-lamp microscope according to the Fantes scale. Myofibroblast generation was detected with immunocytochemistry for alpha-smooth muscle actin (alpha-SMA) and cells were quantitatively analyzed. RESULTS: No difference was noted between the two groups in alpha-SMA + myofibroblasts 4 weeks after surgery (43.6 +/- 2.0/400X field and 45.7 +/- 4.8/400X field in ethanol and mechanical groups, respectively) (P=.10). A slight difference was noted but did not reach statistical significance with regard to stromal haze between ethanol and mechanical groups (2.0 +/- 0.5 and 2.3 +/- 0.4, respectively, P=.063). The ethanol and mechanical groups were statistically different when compared to controls regarding stromal haze and alpha-SMA+ cells (P <.0001 for all comparisons). CONCLUSIONS:No difference was noted in clinical haze or myofibroblast generation between corneas that had PRK with mechanical,or ethanol epithelial debridement. [J Refract Surg., 2008;24:923-927.]

Structural evaluation of the effects of chronic ethanol ingestion on the testis of Calomys callosus

Chronic exposure to ethanol may results in pathophysiologic changes in cellular function. The present work was designed to investigate the morphology of testis submitted to experimental ethanol ingestion. Experimental animals were divided into two groups. The control group (n = 23) received a solid diet and tap water and the alcoholic group (n = 23) received the same solid diet and ethanol P.A. diluted 20% in water (v/v). After 120 days of treatment, all animals were anesthetized, weighed and sacrificed. Testosterone and luteinizing hormone levels in serum were lower in the alcoholic group than in the control group. Histological and ultrastructural alterations were observed in the testicular alcoholic germinative cells like enormous spaces, lipid droplets accumulation, digestive vacuoles, irregular diameter of the seminiferous tubules and interstitial dilated blood vessels. It was concluded that 20% ethanol provokes lesions on the testis germinative epithelium probably inducing gonadal dysfunction. (C) 2008 Elsevier Ltd. All rights reserved.