Vascular redox imbalance in rats submitted to chronic exercise

Exercise training has been used for treatment/prevention of many cardiovascular diseases, but the mechanisms need to be clarified. Thus, our aim was to compare oxidative stress parameters between rats submitted to a swimming training and sedentary rats (control). Twelve male rats were divided into two groups: control and exercise training. The exercise training had daily 1 h swimming sessions for 8 weeks and a load (5% of its body mass) was placed in rat's tail. Thereafter the animals were killed, aorta and heart were surgically removed and blood was collected. Body mass gain, thiobarbituric acid reactive species (TBARS), carbonyl content, total reactive antioxidant potential (TRAP), total antioxidant reactivity (TAR), superoxide dismutase (SOD) activity and catalase (CAT) activity were evaluted. The trained rats showed a lower body mass gain and no modifications on heart. An increased SOD activity was observed on aorta after the training, but no changes were seen for CAT activity, which led to an increased SOD/CAT ratio. The arterial TBARS was also increased for trained rats. The decrease in TRAP in exercise training was the single modification on plasma. Our findings suggest that the increased SOD activity could play a role in vascular adaptations to exercise training. Copyright © 2010 John Wiley & Sons, Ltd.     

Genotoxic evaluation of the antimicrobial drug, trimethoprim, in cultured human lymphocytes

The antimicrobial drug, trimethoprim, was evaluated for genotoxicity in human peripheral blood lymphocyte cultures set-up from two healthy donors. Sister-chromatid exchanges (SCE) and micronuclei (MN) were scored as genetic endpoints. The treatment was done using different trimethoprim concentrations ranging from 1 to 100 microg/ml. From our results, we can conclude that this drug is able to induce both cytotoxic and moderate genotoxic effects, as revealed by the increases seen in SCE and MN frequencies in cultures from the two donors and, at least, at one of the concentrations tested.     

24-hour changes in circulating prolactin, follicle-stimulating hormone, luteinizing hormone, and testosterone in young male rats subjected to calorie restriction

This work analyzes the effect of calorie restriction on the 24 h variation of pituitary-testicular function in young male Wistar rats by measuring the circulating levels of prolactin, follicle-stimulating hormone (FSH), luteinizing hormone (LH), and testosterone. Control animals were provided an equilibrium calorie diet and the experimental animals a calorie-restriction diet equivalent to 66% of food restriction for four weeks starting on day 35 of life. Different groups of control and experimental rats were killed at 6 h intervals around the clock, beginning 1 h after light on (HALO). Compared to the control animals, the mean secretion of prolactin was augmented and that of LH and testosterone decreased in calorie-restricted rats, whereas FSH release remained unchanged. Significant changes in the 24 h secretory pattern of circulating prolactin, LH, and testosterone occurred in the calorie-restricted rats. These include the appearance of a second maximum of plasma prolactin at 21 HALO, blunting of the LH peak seen at 13 HALO, and phase-shift of the testosterone peak from 13 HALO in controls to 17 HALO in calorie-restricted rats. The significant positive correlation between individual LH and testosterone levels found in controls was no longer observed in calorie-restricted rats. Availability of nutrients presumably affects the mechanisms that modulate the circadian variation of the pituitary-gonadal axis in growing male rats.     

A new heptasubstituted (E)-aurone glucoside and other aromatic compounds of Gomphrena agrestis with biological activity

A new aurone 1 and two known substances, aurantiamide acetate (2) and tiliroside (3), were isolated from the ethanolic extract of Gomphrena agrestis. The structural determination of 1 was based on spectroscopic and spectrometric data. The substance was defined as (E)-3'-O-beta-D-glucopyranosyl-4,5,6,4'-tetrahydroxy-7,2'-dimethoxyaurone. Biological activity of the ethanolic crude extract and isolated compounds against bacteria, fungi and Leishmania amazonensis amastigotes was evaluated. This appears to be the first report documenting aurone and aurantiamide compounds in the Amaranthaceae family. In the evaluation of biological activity the ethanolic extract of G. agrestis and compounds 1, 2, and 3 were shown to be active mainly against Staphylococcus aureus, Staphylococcus epidermidis and Pseudomonas aeruginosa.     

Dpp gradient formation by dynamin-dependent endocytosis: receptor trafficking and the diffusion model

Developing cells acquire positional information by reading the graded distribution of morphogens. In Drosophila, the Dpp morphogen forms a long-range concentration gradient by spreading from a restricted source in the developing wing. It has been assumed that Dpp spreads by extracellular diffusion. Under this assumption, the main role of endocytosis in gradient formation is to downregulate receptors at the cell surface. These surface receptors bind to the ligand and thereby interfere with its long-range movement. Recent experiments indicate that Dpp spreading is mediated by Dynamin-dependent endocytosis in the target tissue, suggesting that extracellular diffusion alone cannot account for Dpp dispersal. Here, we perform a theoretical study of a model for morphogen spreading based on extracellular diffusion, which takes into account receptor binding and trafficking. We compare profiles of ligand and surface receptors obtained in this model with experimental data. To this end, we monitored directly the pool of surface receptors and extracellular Dpp with specific antibodies. We conclude that current models considering pure extracellular diffusion cannot explain the observed role of endocytosis during Dpp long-range movement.     

A novel approach to improve specificity of algal biosensors using wild-type and resistant mutants: an application to detect TNT

A new genetic approach was developed for increasing specificity of microalgal biosensors. This method is based on the use of two different genotypes jointly to detect a given pollutant: (i) a sensitive genotype to obtain sensitivity; and (ii) a resistant mutant to obtain specificity. The method was tested by the development of a microalgal biosensor for the detection of the explosive 2,4,6-trinitrotoluene (TNT) using a wild-type strain (DcG1wt) of Dictyosphaerium chlorelloides (Chlorophyceae) as the sensitive organism, and a TNT-resistant mutant, obtained from DcG1wt strain by a modified Luria-Delbrück fluctuation analysis. The inhibition of chlorophyll a fluorescence of PSII by TNT was used as the biological signal. Significant differences in maximal fluorescence of light-adapted algae (F'(m)) between wild-type DcG1wt cells and TNT-resistant mutants, were observed in all the TNT concentrations tested (from 0.5 to 31.3 mg l(-1)) after only 3 min of exposure. Resistant mutants always exhibited significant higher F'(m) values in the presence of TNT than wild-type cells. These results suggest that the use of two different genotypes (sensitive and resistant to a given pollutant) jointly is a useful method to improve microalgal biosensors specificity.     

Increased tissue PO2 and decreased O2 delivery and consumption after 80% exchange transfusion with polymerized hemoglobin

The O2-carrying blood substitute based on polymerized bovine hemoglobin (PBH) was used to determine efficacy in maintaining tissue Po2 after an 80% isovolemic blood exchange leading to a hematocrit of 19% [5.4 g Hb/dl from red blood cells (RBCs) and 6.3 g Hb/dl from PBH]. Effects were studied in terms of O2 delivery, O2 extraction, and tissue Po2 at the microcirculatory level at 1, 12, and 24 h after exchange transfusion in awake hamsters prepared with a window chamber model. At 1 h after exchange, arteriolar and venular diameters were decreased compared with baseline. Arteriolar diameter did not fully recover at 12 h after exchange, but venular diameter returned to normal. At 24 h after exchange, arteriolar and venular diameters were not different from baseline. Combining diameter and flow velocity data allowed us to calculate arteriolar and venular flows. At 1 h after exchange, arteriolar and venular flow was reduced compared with baseline. Arteriolar flow was lower at 12 h after exchange and recovered after 24 h. The number of capillaries with RBC passage [functional capillary density (FCD)] at 1 h after exchange with PBH was significantly lower than baseline. FCD remained decreased at 12 h; at 24 h after exchange transfusion, FCD was fully recovered. Tissue Po2 was maximal at 1 h after exchange and decreased progressively at 12 and 24 h after exchange. O2 release to the tissue was minimal at 1 h and increased at 12 and 24 h after exchange. These results suggest the impairment of tissue O2 metabolism after introduction of PBH into the circulation, which is mitigated as PBH concentration declines.     

Induction of baroresistance by hydrogen peroxide, ethanol and cold-shock in Saccharomyces cerevisiae

The acquisition of tolerance to high hydrostatic pressure of 220 MPa (HHP) in response to a 0.4 mM hydrogen peroxide, 6% ethanol and cold-shock (10 degrees C) pretreatment for different lengths of times was studied in the yeast Saccharomyces cerevisiae. The protection conferred by these different treatments was similar ( approximately 3 log cycles) and time-dependent. Analysis of the induction of the most pressure up-regulated genes under these conditions was investigated by RT-PCR. Our results revealed that the cell stress response to HHP shares common features with hydrogen peroxide and ethanol stresses, but differs in some way to cold-shock.     

Biologic data of Macaca mulatta, Macaca fascicularis, and Saimiri sciureus used for research at the Fiocruz primate center

Physiological parameters of laboratory animals used for biomedical research is crucial for following several experimental procedures. With the intent to establish baseline biologic parameters for non-human primates held in closed colonies, hematological and morphometric data of captive monkeys were determined. Data of clinically healthy rhesus macaques (Macaca mulatta), cynomolgus monkeys (Macaca fascicularis), and squirrel monkeys (Saimiri sciureus) were collected over a period of five years. Animals were separated according to sex and divided into five age groups. Hematological data were compared with those in the literature by Student's t test. Discrepancies with significance levels of 0.1, 1 or 5% were found in the hematological studies. Growth curves showed that the sexual dimorphism of rhesus monkeys appeared at an age of four years. In earlier ages, the differences between sexes could not be distinguished (p < 0.05). Sexual dimorphism in both squirrel monkeys and cynomolgus monkeys occurred at an age of about 32 months. Data presented in this paper could be useful for comparative studies using primates under similar conditions.