Generation of aldehyde-derived protein modifications in ethanol-exposed heart

Background: Although excessive ethanol consumption is known to lead to a variety of adverse effects in the heart, the molecular mechanisms of such effects have remained poorly defined. We hypothesized that posttranslational covalent binding of reactive molecular species to proteins occurs in the heart in response to acute ethanol exposure. Methods: The generation of protein adducts with several aldehydic species was examined by using monospecific antibodies against adducts with malondialdehyde (MDA), acetaldehyde (AA), MDA-AA hybrids, and hydroxyethyl radicals. Specimens of heart tissue were obtained from rats after intraperitoneal injections with alcohol (75 mmol/kg body weight) with or without pretreatment with cyanamide (0.05 mmol/kg body weight), an aldehyde dehydrogenase inhibitor. Results: The amounts of MDA and unreduced AA adducts were found to be significantly increased in the heart of the rats treated with ethanol, cyanamide, or both, whereas no other adducts were detected in statistically significant quantities. Immunohistochemical studies for characterization of adduct distribution revealed sarcolemmal adducts of both MDA and AA in the rats treated with ethanol and cyanamide in addition to intracellular adducts, which were also present in the group treated with ethanol alone. Conclusions: These findings support the role of enhanced lipid peroxidation and the generation of protein-aldehyde condensates in vivo as a result of excessive ethanol intake. These findings may have implications in the molecular mechanisms of cardiac dysfunction in alcoholics.

Characterization of sugar cane waste biomass derived chars from pressurized gasification

There is interest in the use of sugar cane waste biomass for electricity cogeneration, by integrated gasification combined cycle (IGCC) processes. This paper describes one aspect of an overall investigation into the reactivity of cane wastes under pressurized IGGC conditions, for input into process design. There is currently a gap in understanding the morphological transformations experienced by cane waste biomass undergoing conversion to char during pressurized gasification, which is addressed by this work. Char residuals remaining after pressurized pyrolysis and carbon dioxide gasification were analysed by optical microscope, nitrogen (BET) adsorption analysis, SEM/EDS, TEM/EDS and XPS techniques. The amorphous cane plant silica structures were found to remain physically intact during entrained flow gasification, but chemically altered in the presence of other inorganic species. The resulting crystalline silicates were mesoporous (with surface areas of the order of 20 m(2) g(-1)) and contributed to much of the otherwise limited pore volume present in the residual chars. Coke deposition and intimate blending of the carbonaceous and inorganic species was identified. Progressive sintering of the silicates appeared to trap coke deposits in the pore network. As a result ash residuals showed significant organic contents, even after extensive additional oxidation in air. The implications of the findings are that full conversion of cane trash materials under pressurized IGCC conditions may be significantly hampered by the silica structures inherent in these biomass materials and that further research of the contributing phenomena is recommended.

Adsorption kinetics for the removal of chromium(VI) from aqueous solution by adsorbents derived from used tyres and sawdust

The batch removal of hexavalent chromium (Cr(Vl)) from wastewater under different experimental conditions using economic adsorbents was investigated in this study. These adsorbents were produced from the pyrolysis and activation of the waste tyres (TAC) and from the pyrolysis of sawdust (SPC). The performance of these adsorbents against commercial activated carbon F400 (CAC) has also been carried out. The removal was favoured at low pH, with maximum removal at pH = 2 for all types of carbon. The effects of concentration, temperature and particle size have been reported. All sorbents were found to efficiently remove Cr(VI) from solution. The batch sorption kinetics have been tested for a first-order reversible reaction, a first-order and second-order reaction. The rate constants of adsorption for all these kinetic models have been calculated. The applicability of the Langmuir isotherm for the present system has been tested at different temperatures. The thermodynamic parameters (AGO, K,) obtained indicate the endothermic nature of Cr(Vl) adsorption on TAC, SPC and CAC. (C) 2001 Elsevier Science B.V. All rights reserved.

Two dimensional computational fluid dynamic models for waste stabilisation ponds

Traditional waste stabilisation pond (WSP) models encounter problems predicting pond performance because they cannot account for the influence of pond features, such as inlet structure or pond geometry, on fluid hydrodynamics. In this study, two dimensional (2-D) computational fluid dynamics (CFD) models were compared to experimental residence time distributions (RTD) from literature. In one of the-three geometries simulated, the 2-D CFD model successfully predicted the experimental RTD. However, flow patterns in the other two geometries were not well described due to the difficulty of representing the three dimensional (3-D) experimental inlet in the 2-D CFD model, and the sensitivity of the model results to the assumptions used to characterise the inlet. Neither a velocity similarity nor geometric similarity approach to inlet representation in 2-D gave results correlating with experimental data. However. it was shown that 2-D CFD models were not affected by changes in values of model parameters which are difficult to predict, particularly the turbulent inlet conditions. This work suggests that 2-D CFD models cannot be used a priori to give an adequate description of the hydrodynamic patterns in WSP. (C) 1998 Elsevier Science Ltd. All rights reserved.

Selection of a strain of Aspergillus for the production of citric acid from pineapple waste in solid-state fermentation

Aspergillus foetidus ACR I 3996 (=FRR 3558) and three strains of Aspergillus niger ACM 4992 (=ATCC 9142), ACM 4993 (=ATCC 10577), ACM 4994 (=ATCC 12846) were compared for the production of citric acid from pineapple peel in solid-state fermentation. A. niger ACM 4992 produced the highest amount of citric acid, with a yield of 19.4 g of citric acid per 100 g of dry fermented pineapple waste under optimum conditions, representing a yield of 0.74 g citric acid/g sugar consumed. Optimal conditions were 65% (w/w) initial moisture content, 3% (v/w) methanol, 30 degrees C, an unadjusted initial pH of 3.4, a particle size of 2 mm and 5 ppm Fe2+. Citric acid production was best in flasks, with lower yields being obtained in tray and rotating drum bioreactors.

Proliferation in monocyte-derived dendritic cell cultures is caused by progenitor cells capable of myeloid differentiation

Dendritic cells (DC) can be generated by culture of adherent peripheral blood (PB) cells in the presence of granulocyte-macrophage colony-stimulating factor (GM-CSF) and interleukin-4 (IL-4). There is controversy as to whether these DC arise from proliferating precursors or simply from differentiation of monocytes. DC were generated from myeloid-enriched PB non-T cells or sorted monocytes. DC generated from either population functioned as potent antigen-presenting cells. Uptake of [H-3]-thymidine was observed in DC cultured from myeloid-enriched non-T cells. Addition of lipopolysaccharide or tumor necrosis factor-alpha led to maturation of the DC, but did not inhibit proliferation. Ki67(+) cells were observed in cytospins of these DC, and by double staining were CD3(-)CD19(-)CD11c(-)CD40(-) and myeloperoxidase(+), suggesting that they were myeloid progenitor cells. Analysis of the starting population by flow cytometry demonstrated small numbers of CD34(+)CD33(-)CD14(-) progenitor cells, and numerous granulocyte-macrophage colony-forming units were generated in standard assays. Thus, production of DC in vitro from adherent PB cells also enriches for progenitor cells that are capable of proliferation after exposure to GM-CSF. Of clinical importance, the yield of DC derived in the presence of GM-CSF and IL-4 cannot be expanded beyond the number of starting monocytes. (C) 1998 by The American Society of Hematology.

Small molecular probes for G-protein-coupled C5a receptors: Conformationally constrained antagonists derived from the C terminus of the human plasma protein C5a

Activation of the human complement system of plasma proteins in response to infection or injury produces a 4-helix bundle glycoprotein (74 amino acids) known as C5a. C5a binds to G-protein-coupled receptors on cell surfaces triggering receptor-ligand internalization, signal transduction, and powerful inflammatory responses. Since excessive levels of C5a are associated with autoimmune and chronic inflammatory disorders, inhibitors of receptor activation may have therapeutic potential. We now report solution structures and receptor-binding and antagonist activities for some of the first small molecule antagonists of C5a derived from its hexapeptide C terminus. The antagonist NMe-Phe-Lys-Pro-D-Cha-Trp-D-Arg-CO2H (1) surprisingly shows an unusually well-defined solution structure as determined by H-1 NMR spectroscopy. This is one of the smallest acyclic peptides found to possess a defined solution conformation, which can be explained by the constraining role of intramolecular hydrogen bonding. NOE and coupling constant data, slow deuterium exchange, and a low dependence on temperature for the chemical shift of the D-Cha-NH strongly indicate an inverse gamma turn stabilized by a D-Cha-NH ... OC-Lys hydrogen bond. Smaller conformational populations are associated with a hydrogen bond between Trp-NH ... OC-Lys, defining a type II beta turn distorted by the inverse gamma turn incorporated within it. An excellent correlation between receptor-affinity and antagonist activity is indicated for a limited set of synthetic peptides. Conversion of the C-terminal carboxylate of 1 to an amide decreases antagonist potency 5-fold, but potency is increased up to 10-fold over 1 if the amide bond is made between the C-terminal carboxylate and a Lys/Orn side chain to form a cyclic analogue. The solution structure of cycle 6 also shows gamma and beta turns; however, the latter occurs in a different position, and there are clear conformational changes in 6 vs 1 that result in enhanced activity. These results indicate that potent C5a antagonists can be developed by targeting site 2 alone of the C5a receptor and define a novel pharmacophore for developing powerful receptor probes or drug candidates.

Chronic ethanol treatment leads to increased ornithine decarboxylase activity: Implications for a role of polyamines in ethanol dependence and withdrawal

Recent research has focused on the N-methyl-D-aspartate receptor system as a major site of ethanol action in the brain and specifically on compensatory changes in the expression of the polyamine-sensitive NR2B subunit. Therefore, we examined the effects of chronic ethanol treatment on polyamine homeostasis in the rat brain. Wistar rats were made dependent by ethanol vapor inhalation. This caused a rise in hippocampal ornithine decarboxylase (ODC) activity that was correlated with the appearance of physiological dependence. ODC activity returned to control levels within 3 days of ethanol withdrawal. Enzyme activity also increased in the cerebral cortex, striatum, and cerebellum of the ethanol-dependent rats. The concentration of the polyamines (putrescine, spermidine, and spermine) in the hippocampus was increased in ethanol-dependent rats. Injection of the ODC inhibitor, gamma-difluoromethylornithine (500 mg/kg) at the onset of withdrawal resulted in a significant reduction in the severity of withdrawal behaviors. The level of ODC activity and the severity of withdrawal behaviors were positively correlated. Perturbed polyamine homeostasis may represent an important molecular component in the initiation of ethanol withdrawal behaviors in the ethanol-dependent rat.

Ethanol inhibition of brain ornithine decarboxylase activity in the postnatal rat

The purpose of this study was to determine the relationship between ornithine decarboxylase activity (ODC; a marker for perturbed cell development), the blood alcohol level, and alcohol-induced microencephaly in the developing rat brain after binge treatment with ethanol vapour. By manipulating ethanol flow we were able to adjust vapour concentrations (24-65 mg ethanol/l air) such that an acute exposure of ethanol vapour for 3 h resulted in a range of blood alcohol levels (2.3-5.5 mg/ml). Acute studies showed that ethanol dose-dependently inhibited rat hippocampal and cerebellar ODC activity at PND4-PND10. There was a significant correlation between the blood alcohol level and degree of inhibition at all ages tested. Chronic treatment from PND4 to PND9 caused a significant decrease in both brain to body weight ratio and in hippocampal and cerebellar ODC activities at PND10. These results indicate that ethanol-induced disruption in ODC could play a significant role in ethanol's teratogenic effects during early postnatal development. (C) 1998 Elsevier Science Inc.

Proliferation in monocyte-derived dendritic cell cultures is due to cells capable of myeloid differentiation

Dendritic cells (DC) can be generated by culture of adherent peripheral blood (PB) cells in the presence of granulocyte-macrophage colony-stimulating factor (GM-CSF) and interleukin-4 (IL-4). There is controversy as to whether these DC arise from proliferating precursors or simply from differentiation of monocytes. DC were generated from myeloid-enriched PB non-T cells or sorted monocytes. DC generated from either population functioned as potent antigen-presenting cells. Uptake of [H-3]-thymidine was observed in DC cultured from myeloid-enriched non-T cells. Addition of lipopolysaccharide or tumor necrosis factor-alpha led to maturation of the DC, but did not inhibit proliferation. Ki67(+) cells were observed in cytospins of these DC, and by double staining were CD3(-)CD19(-)CD11c(-)CD40(-) and myeloperoxidase(+), suggesting that they were myeloid progenitor cells. Analysis of the starting population by flow cytometry demonstrated small numbers of CD34(+)CD33(-)CD14(-) progenitor cells, and numerous granulocyte-macrophage colony-forming units were generated in standard assays. Thus, production of DC in vitro from adherent PB cells also enriches for progenitor cells that are capable of proliferation after exposure to GM-CSF. Of clinical importance, the yield of DC derived in the presence of GM-CSF and IL-4 cannot be expanded beyond the number of starting monocytes. (C) 1998 by The American Society of Hematology.

A comparison of lipopolysaccharide-induced hepatitis in ethanol-fed Wistar and Lewis rats

Elevated concentrations of plasma proinflammatory cytokines have been detected in patients with alcoholic hepatitis (AH) and in a model of lipopolysaccharide-induced hepatitis in ethanol-fed Wistar rats. These cytokines have been implicated in the pathogenesis of the liver damage. Considering the likely involvement of the immune system in AH, and the frequent use of Lewis rats in autoimmune disease models, Lewis rats were examined in the model to determine whether they would more closely mimic the immune status of a chronic alcoholic and be a preferable strain for use in future experiments. Lipopolysaccharide-induced hepatic tumor necrosis factor-cu, interleukin-1 alpha, interleukin-1 beta, and interleukin-6 mRNA expression was examined in both rat strains. The overall pattern of histological (panlobular piecemeal necrosis) and biochemical liver damage (plasma ALT levels), and cytokine expression was similar in both strains. Thus, it would appear that, despite the known susceptibility of Lewis rats to autoimmune phenomena, they do not respond to the experimental regime significantly better than Wistar rats. This study confirms that unknown mediators are contributing to the liver damage seen in this model and possibly in AH.

Chemokine and cell adhesion molecule mRNA expression and neutrophil infiltration in lipopolysaccharide-induced hepatitis in ethanol-fed rats

Neutrophil infiltration is a feature of alcoholic hepatitis (AH), and although the mechanism by which this occurs is unclear, it may involve a chemotactic gradient. We used lipopolysaccharide (LPS) to induce, in ethanol-fed rats, liver damage similar to that seen in AH. To our knowledge, this study is the first to examine the effect of ethanol on LPS-stimulated chemokine mRNA expression in this model. Hepatic cytokine-induced neutrophil chemoattractant (CINC)-1, CINC-2, monocyte chemoattractant protein-1 (MCP-1), macrophage inflammatory protein (MIP)-1 beta, MIP-2, and eotaxin mRNA levels were elevated 1 to 3 hr post-LPS in both groups. Maximal expression of MIP-2 and MCP-1 mRNA was higher in ethanol-fed rats 1 hr post-LPS, whereas CINC-2 mRNA expression was elevated above controls at 12 to 24 hr. Hepatic intercellular adhesion molecule-1 and vascular cell adhesion molecule-1 mRNA levels were elevated in both groups at 1 hr, whereas L-selectin expression in ethanol-fed rats was elevated above controls at 12 to 24 hr. Hepatic neutrophil infiltration was highest during maximal hepatocyte necrosis. These data suggest that cell adhesion molecules, in conjunction with elevated cytokines and the subsequently induced chemokines, may assist in the formation of a chemotactic gradient within the liver, causing the neutrophil infiltration seen both in this model and possibly in AH.

Adsorption characteristics of phenolic compounds onto coal-reject-derived adsorbents

Carbonaceous adsorbents were prepared by heat treatment of coal reject at 600 degrees C, after chemical treatment in HNO3, H2SO4, and NaOH at 25 and 75 degrees C. Pore structure characterization and the phenol adsorption capacities of the adsorbents showed that nitric acid pretreatment significantly enhanced the surface properties, consequently the adsorption capacities of the adsorbents. A number of samples were subsequently prepared by carbonizing coal reject at 600 degrees C, after pretreatment in HNO3 under various conditions. The acid concentration, residence time, and reaction temperature were varied to obtain adsorbents with various pore structures. The adsorption capacities of the derived adsorbents for phenol, p-nitrophenol, and benzene were measured to gain further insights into the pore structure evolution. Adsorption isotherms of phenol, p-nitrophenol, and p-chlorophenol on the best adsorbent prepared were determined and correlated with theoretical isotherm equations, such as the Langmuir, Freundlich, and Redlich-Peterson equations.

Subantarctic Macquarie Island - a model ecosystem for studying animal-derived nitrogen sources using N-15 natural abundance

Plants collected from diverse sites on subantarctic Macquarie Island varied by up to 30 parts per thousand in their leaf delta(15)N values. N-15 natural abundance of plants, soils, animal excrement and atmospheric ammonia suggest that the majority of nitrogen utilised by plants growing in the vicinity of animal colonies or burrows is animal-derived. Plants growing near scavengers and animal higher in the food chain had highly enriched delta(15)N values (mean = 12.9 parts per thousand), reflecting the highly enriched signature of these animals' excrement, while plants growing near nesting penguins and albatross, which have an intermediate food chain position, had less enriched delta(15)N values (> 6 parts per thousand). Vegetation in areas affected by rabbits had lower delta(15)N values (mean = 1.2 parts per thousand), while the highly depleted delta(15)N values (below -5 parts per thousand) of plants at upland plateau sites inland of penguin colonies, suggested that a portion of their nitrogen is derived from ammonia (mean N-15 = -10 parts per thousand) lost during the degradation of penguin guano. Vegetation in a remote area had delta(15)N values near -2 parts per thousand. These results contrast with arctic and subarctic studies that attribute large variations in plant N-15 values to nitrogen partitioning in nitrogen-limited environments. Here, plant N-15 reflects the N-15 Of the likely nitrogen sources utilised by plants.