Parâmetros bioquímicos de equinos submetidos à simulação de prova de enduro recebendo dietas com adição de óleo de soja

Com o objetivo de verificar o efeito da adição de níveis crescentes de óleo no concentrado sobre a atividade plasmática das enzimas creatina quinase (CK), aspartato aminotransferase (AST) e lactato desidrogenase (LDH) como indicativo de metabolismo energético, foram fornecidas dietas experimentais compostas de cinco níveis de óleo (controle, 6, 12, 18 e 24% do concentrado). Utilizaram-se 20 equinos da raça Árabe, peso médio de 400 kg, submetidos a prova de enduro de 80 km em esteira rolante. O enduro foi dividido em quatro anéis de 20 km, com duração média de 1 hora e dez minutos. A adição de óleo e a distância percorrida tiveram efeitos sobre as variáveis AST, CK e LDH, que apresentaram as respectivas expressões: AST (7,045-0,2292x+0,007991x2+0,008517z- 0,0003282xz), CK (8,06-,07020x+0,05546x2-0,001262x3+0,01204z+0,0006207xz) e LDH (6,624-0,3522x+0,03448x2-0,0008382x3+0,02401z-0,0007489xz) . O óleo é uma importante e bem aproveitada fonte de energia para equinos em exercício, pois sua adição na dieta de animais submetidos a prova de enduro promoveu alteração metabólica que favorece a produção de energia. O metabolismo animal poupou suas reservas energéticas oriundas da glicose, favorecendo a utilização do óleo. A menor atividade plasmática das enzimas AST, CK e LDH com a adição de óleo nas dietas indica direcionamento do metabolismo energético para a β-oxidação. Como apresentam várias isoenzimas, as enzimas estudadas atuam amplamente no metabolismo energético, favorecendo a constante reposição de ATP ao longo do exercício.

Microbial populations and activities in sewage sludge and phosphate fertilizer-amended soil

A greenhouse study was conducted to determine the number of microbial populations and activities in sewage sludge and phosphate fertilizer-amended dark red latosoil for cultivation of tomato plants. Sewage sludge was applied at doses of 0, 10, 20, 40, 80 and 160 t ha(-1), and phosphate (P2O5) at doses of 0, 100, 200, 400 and 800 kg ha(-1). The bacterial populations increased as a function of sewage sludge and phosphate application. Fungal populations were not affected by the application of phosphate alone but were increased by the application of sewage sludge. Phosphate doses higher than 100-200 kg ha(-1) in combination with sewage sludge inhibited both bacterial and fungal growth. The responses determined by microbial counts were reflected in the microbial biomass values, with a more significant effect of sewage sludge than of phosphate or of a combination of both. These results confirm the need for a carbon and energy source (represented here by sewage sludge) for microbial growth in a soil poor in organic matter. Dehydrogenase and urease activities reflected the results of the microbial populations due to the effect of sewage sludge and phosphate, but no satisfactory result was obtained for phosphatase. Urease activity was expressed by a linear regression equation as the result of the effect of sewage sludge, and by a quadratic regression equation as the result of the effect of phosphate. All parameters investigated showed a significant correlation with bacterial counts but not with fungal counts, indicating a greater effect of sewage sludge and phosphate on bacteria than on fungi.

Evolution and population structure of africanized honey bees in Brazil: Evidence from spatial analysis of morphometric data

In recent years, studies based on isoenzymatic patterns of geographic variation have revealed that what is usually called the Africanized honey bee does not constitute a single population. Instead, several local populations exist with various degrees of admixture with European honey bees. In this paper, we evaluated new data on morphometric patterns of Africanized honey bees collected at 42 localities in Brazil, using univariate and multivariate (canonical) trend surface and spatial autocorrelation analyses. The clinal patterns of variation found for genetically independent characters (wing size characters and some wing venation angles) are concordant with previous studies of malate dehydrogenase (MDH) allelic frequencies and support the hypothesis that larger honey bees in southern and southeastern Brazil originated by racial admixture in the initial phases of African honey bee colonization. Geographic variation patterns of Africanized honey bee populations reflect a demic diffusion process in which European genes were gradually lost because of the higher fitness of the African gene pool in Neotropical environmental conditions.

Walker 256 tumour growth causes marked changes of glutamine metabolism in rat small intestine

The effect of Walker 256 tumour growth on the metabolism of glucose and glutamine in the small intestine of rats was examined. Walker 256 tumour has been extensively used as an experimental model to induce cancer cachexia in rats. Walker 256 tumour growth decreased body weight and small intestine weight and length. The activities of glucose-6-phosphate dehydrogenase and phosphate-dependent glutaminase were reduced in the proximal, median and distal portions of the intestine. Glutamine oxidation was reduced in the proximal portion only. The decrease in glutaminase activity was not due to a low synthesis of the protein as indicated by Western blotting analysis. Hexokinase and citrate synthase activities were not changed by the tumour. These findings led us to postulate that tumour growth impairs glutamine metabolism of small intestine but the mechanism involved remains to be elucidated. Copyright (C) 2001 John Wiley Sons, Ltd.

Environmental cadmium exposure and metabolic responses of the Nile tilapia, Oreochromis niloticus

The contamination of water by metal compounds is a worldwide environmental problem. This study was undertaken to evaluate the impact of short-term cadmium exposure on metabolic patterns of the freshwater fish Oreochromis niloticus. The fish were exposed to 320, 640, 1280 and 2560 mug/l sublethal concentrations of Cd++ (CdCl2) in water for 7 days. The specific activities of the enzymes phosphofructo kinase (PFK-E.C.2.7.1.11.), lactate dehydrogenase (LDH-E.C.1.1.1.27.) and creatine kinase (CK-E.C.2.7.3.2.) were decreased in white muscle after cadmium treatments, indicating decreases in the capacity of glycolysis in this tissue. Cadmium exposure induced increased glucose concentration in white muscle of fish. on the other hand, cadmium exposure at sublethal concentrations increased phosphofructo kinase and LDH in red muscle of fish. Cadmium significantly decreased total protein concentrations in liver and white muscle regardless of tissue glycogen levels. The data suggest that cadmium acts as a stressor, leading to metabolic alterations similar to those observed in starvation. (C) 2001 Elsevier B.V. Ltd. All rights reserved.

Differential/combined effect of water contamination with cadmium and nickel on tissues of rats

The contamination of water by metal compounds is a worldwide environmental problem. Concentrations of metals are widely related to biochemical values which are used in disease diagnosis due to environmental toxicity. The acute combined effects of cadmium and nickel on biochemical parameters were determined and compared with those of Cd2+ or Ni2+ alone in rats. Male adult rats were given drinking solutions of CdCl2 [Cd(II) cation, 100 mg/liter] or NiSO4 [Ni(II) cation, 100 mg/liter]. For the combined treatment, the animals (Ni+Cd) received both Ni(II)) cation (100 mg/liter) and Cd(II) cation (100 mg/liter). Nickel treatment induced increased alanine transaminase (ALT) activity and hepatotoxicity, but not renal injury. In contrast, cadmium exposure produced hepatic, renal and myocardial damage, characterized by increased creatinine, total and direct bilirubin concentrations and increased ALT and lactate dehydrogenase (LDH) activities. The combined effect Ni-Cd is less toxic than cadmium alone, suggesting antagonism between these toxicants. The toxicity of nickel and cadmium, alone and in combination, decreased Cu-Zn superoxide dismutase (SOD) activity and increased lipoperoxide formation. (C) 1998 Elsevier B.V. Ltd. All rights reserved.

Physiological responses of pressed baker's yeast cells pre-treated with citric, malic and succinic acids

The dough-leavening power of baker's yeast, Saccharomyces cerevisiae, is strongly influenced by conditions under which the pressed yeast is maintained prior to bread dough preparation. In this study, the influence of the yeast cell's pre-treatment with organic acids (malic, succinic, and citric acids) was investigated at a wide range of pH values when the pressed yeast samples were exposed to 30 degrees C. Increased fermentative activity was observed immediately after pre-treatment of the cells with organic acids. When the pH of the pressed yeast containing added citric acid was raised from 3.5 to 7.5, increases in both fermentative and maltase activities were obtained. Improvements in viability and levels of total protein were also observed during storage in the presence of citric acid, notably at pH 7.5. Glycerol-3-phosphate dehydrogenase activity and levels of internal glycerol also increased in the presence of citrate. on the other hand, pressed yeast samples containing succinic acid at pH 7.5 showed decreased viability during storage despite the maintenance of high levels of fermentative activity, similar to pressed yeast containing malic acid at pH 4.5 and 7.5. Decreases in intracellular levels of trehalose were observed during storage in all cases. Overall, the results of this study revealed the potential benefits of adding organic acids to pressed yeast preparations for baking purposes.

Triiodothyronine mimics the effects of estrogen in breast cancer cell lines

MCF-7 (estrogen receptor positive - ER(+)) and MDA-MB-231 (estrogen receptor negative - ER(-)) are human breast cancer cell lines which express functional thyroid hormone receptors (c-erb A alpha 1 and c-erb beta 1) as indicated by stimulation of mitochondrial alpha-glycerophosphate dehydrogenase. In MCF-7, mimicking E(2), T-3 stimulated growth in a dose-dependent (10(10) M-10(-8) M) manner, induced the expression of progesterone receptor and growth factor TGF alpha mRNAs and inhibited that of TGF beta mRNA; T-3 also increased progesterone binding and LDH5 isozyme activities. None of these effects were observed in (ER(-)) MDA-MB-231 cells. 10(-6) M tamoxifen (TAM) reverted growth stimulation, suppressed progesterone receptor and TGF alpha mRNA induction and restored TGF beta mRNA to control levels in T-3-treated MCF-7 cells. That T-3 is acting in MCF-7 cells via its binding to ER is suggested by the immunoprecipitation of pre-bound I-125-T-3 from MCF-7 nuclear extracts by an ER-specific monoclonal antibody and by the displacement of H-3-estradiol binding to ER by radioinert T-3. Copyright (C) 1996 Elsevier B.V. Ltd.

Diets rich in saturated and polyunsaturated fatty acids: Metabolic shifting and cardiac health

OBJECTIVE: the aim of this study was to determine the effects of diets rich in saturated and polyunsaturated fatty acids on metabolic pathways and the relation of metabolic shifting to oxidative stress in cardiac tissue.METHODS: Male Wistar rats (age, 60 d; n = 10) were fed with a control low-fat diet, a diet rich in saturated fatty acids (SFAs), or a diet rich in polyunsaturated fatty acids (PUFAs). After 5 wk of treatment, sera were used for protein and lipid determinations. Protein, glycogen, triacylglycerol, lactate dehydrogenase, citrate synthase, beta-hydroxyacyl coenzyme-A dehydrogenase, catalase, glutathione peroxidase, superoxide dismutase, lipoperoxide, and lipid hydroperoxide were measured in cardiac tissue.RESULTS: the SFA group had higher triacylglycerol, cholesterol, low-density lipoprotein cholesterol, and atherogenic index (ratio of cholesterol to high-density lipoprotein) than did the PUFA and control groups. The PUFA group had low serum cholesterol, triacylglycerol, and low-density lipoprotein cholesterol as compared with the SFA group. SFA increased myocardial lipid hydroperoxide and diminished glutathione peroxidase. Despite the beneficial effects on serum lipids, the PUFA diet led to the highest levels of myocardial lipoperoxide and lipid hydroperoxide and diminished superoxide dismutase and catalase activities. The PUFA effects were related to increased feed efficiency, increased susceptibility to lipoperoxidation, and metabolic shifting in cardiac tissue. PUFA elevated triacylglycerol levels and decreased myocardial glycogen concentrations. The ratios of lactate dehydrogenase to citrate synthase and beta-hydroxyacyl coenzyme-A dehydrogenase to citrate synthase were increased, indicating myocardial reduction of tricarboxylic acid cycle.CONCLUSIONS: PUFAs have been recommended as a therapeutic measure in preventive medicine to lower serum cholesterol, but PUFAs increased oxidative stress in the heart by providing cardiac susceptibility to lipoperoxidation and shifting the metabolic pathway for energy production. The control diet, which was much lower in calories and fat, produced better overall clinical outcomes, better fat profiles, and less oxidative stress than did the diets rich in fatty acids.

Determination of malic acid in real samples by using enzyme immobilized reactors and amperometric detection

The malate dehydrogenase (MDH) and ascorbate oxidase were immobilized independently, onto silanized controlled porous silica and packed in a tygon tube. The reactors were inserted in the flow system, and the malic acid was determined by measurement of NADH produced by enzymatic reaction. The NADH was reoxidized in a wall jet cell that consisted of spectrographic graphite, Ag/AgCl, KCl(sat), and steel needle as work, reference, and counter electrodes, respectively. The current intensities were measured at 390 mV. The malate calibration curve shows a linear range from 5.0 x 10(-6) to 1.0 x 10(-4) molL(-1), the lifetime was 40 analyses, after that a decrease of 20% on the response is observed. Three different citric juices were analyzed and a good correlation between the proposed method and spectrophotometric commercial kit were obtained.

Impact of the training program on lipid profile and cardiac health

The aim of this study was to investigate the effects of training programs on serum lipid profile and myocardial oxidative stress. Male Wistar rats (2 mo-old) were divided into three groups (n=8): sedentary (S), loadless trained (T) and trained-overload 2% body weight (TL). T and TL were trained through swimming for 9 weeks. T and TL rats had increased myocardial lipoperoxide (TBA) and lipid hydroperoxide (HP), whereas HP was higher in TL than in T animals. Superoxide dismutase (SOD) activities were lowest in TL. Myocardial glutathione peroxidase (GSH-Px) was lower in TL than in T and S rats. TL decreased HDL-cholesterol and increased LDL-cholesterol. The serum lactate dehydrogenase and TBA were increased, while SOD and GSH-Px activities were decreased in TL rats. Loadless training was able to improve HDL-cholesterol and to reduce LDL-cholesterol. In conclusion, the loadless training program induced beneficial effects on lipid profile, while overload training induced dyslipidemic profile that was associated with serum oxidative stress. The overload training program was deleterious relative to loadless training program, increasing myocardial oxidative stress.

Effects of dietary macronutrient content on energy metabolism and uncoupling protein mRNA expression in broiler chickens

The objective of the present study was to investigate the effects of dietary macronutrient ratio on energy metabolism and on skeletal muscle mRNA expression of avian uncoupling protein (UCP), thought to be implicated in thermogenesis in birds. Broiler chickens from 2 to 6 weeks of age received one of three isoenergetic diets containing different macronutrient ratios (low-lipid (LL) 30 v. 77 g lipid/kg-, low-protein (LP) 125 v. 197 g crude protein (N X 6.25)/kg; low-carbohydrate (LC) 440 v. 520 g carbohydrate/kg). LP chickens were characterised by significantly lower body weights and food intakes compared with LL and LC chickens (-47 and -38% respectively) but similar heat production/kg metabolic body weight, as measured by indirect calorimetry, in the three groups. However, heat production/g food ingested was higher in animals receiving the LP diet (+41%, P<0.05). These chickens also deposited 57% less energy as protein (P<0.05) and 33% more as fat. No significant differences in energy and N balances were detected between LL and LC chickens. The diets with the higher fat contents (i.e. The LP and LC diets) induced slightly but significantly higher relative expressions of avian UCP mRNA in gastrocnemius muscle, measured by reverse transcription-polymerase chain reaction, than the LL diet (88 and 90 v. 78% glyceraldehyde-3-phosphate dehydrogenase respectively, P<0.05). Our present results are consistent with the recent view that UCP homologues could be involved in the regulation of lipid utilisation as fuel substrate and provide evidence that the macronutrient content of the diet regulates energy metabolism and especially protein and fat deposition.

In vitro study of antiviral activity of mycophenolic acid on Brazilian orthobunyaviruses

Objective: Oropouche, Caraparu, Guama, Guaroa and Tacaiuma are ssRNA viruses that belong to the genus Orthobunyavirus and have been associated with human febrile illnesses and/or encephalitis. In this study, we evaluated the antiviral action of mycophenolic acid (MPA) on these orthobunyaviruses to achieve a therapeutic agent to treat the diseases caused by these viruses. Methods: the in vitro antiviral evaluation to MPA was done by using plaque assay at different periods of treatment. Results: Results showed that MPA at a concentration of 10 mu g/ml has significant antiviral activity on Tacaiuma virus when treatment was initiated either 24 h before or 2 h after viral infection. Moreover, MPA has an inhibitory effect on Guama virus replication, but only when treatment was initiated before cell infection. Addition of guanosine in the culture reverted the inhibitory effect of MPA on Tacaiuma and Guama viruses, suggesting that the antiviral activity of this substance was via depletion of the intracellular guanosine pool. Conclusion: Our results suggest that MPA would not be a good therapeutic agent to treat the diseases caused by Oropouche, Caraparu, Guama, Guaroa, and Tacaiuma viruses.

Investigations on the new free radical scavenger polynitroxyl-albumin to prevent ischemia and reperfusion injury after orthotopic heart transplantation in the pig model

Objective: Nitroxides have strong antioxidant capacity but their effectiveness is limited by their rapid intracellular inactivation. Poly nitroxyl-Albumin (PNA) is capable of regenerating inactivated nitroxide. We tested the effect of PNA against reperfusion injury in heart transplantation. Methods: Pig hearts were transplanted orthotopically. In the control group (n = 9) reperfusion was performed without reperfusion modifications. In the experimental group (n = 10) 1 ml/kg PNA was given before cross-clamp release. Results: Hemodynamic performance was impaired after transplantation in both groups without significant intergroup differences. Plasma malonedialdehyde levels were significantly diminished in the PNA group as compared to the controls. CK-MB levels in both groups were increased within the first 2 h of reperfusion without significant intergroup differences. In contrast, there were found significant higher values of myocardial specific lactate dehydrogenase (LD1) in the controls versus PNA group. Conclusions: PNA was able to reduce lipid peroxidation and attenuate free radical activity. Contractile dysfunction could no be improved, indicating that (a) the radical scavenging effect was to weak or (b) other mechanisms than free oxygen radicals are responsible for myocardial damage in this experimental model. (C) 2001 Elsevier B.V. B.V. All rights reserved.

Reagentless biosensor for isocitrate using one step modified Pt-Ir microelectrode

The Pt-Ir microelectrode modified through one step, electropolymerization is proposed for the isocitrate amperometric biosensor construction. The enzyme (isocitrate dehydrogenase-ICDH), coenzyme (NADP(+)) and mediator (Meldola's Blue) were immobilized onto the microelectrode surface in one step from a PIPES buffer solution containing pyrrole. The optimized experimental conditions were 25 cycles of cyclic voltammetric in a solution containing 3.58 10(-5) mol l(-1) of mediator, 3.51 10(-4) mol l(-1) of coenzyme and 2.68 U ml(-1) of enzyme. In contrast to the biosensor for isocitrate reported in literature, just one enzyme was immobilized and no coenzyme addition in the solution of analysis was necessary. Catalytic currents were proportional to the isocitrate concentration between 7.7 10(-6) and 1.04 10(-4) mol l(-1), showing good repeatability. The detection limit of the proposed biosensor was 3.50 10(-6) mol l(-1), the response time was lower than 20 s, the lifetime was about 30 determinations and no significant interference of sugars and citric acid was verified. Orange juice samples were analysed by both methodology biosensor and spectrophotometric commercial kit, and the obtained results presented a good correlation. The data demonstrated that the developed biosensor is suitable for isocitrate determination in orange juice without matrix interferences. (C) 2001 Elsevier B.V. B.V. All rights reserved.