Leptospirosis severity may be associated with the intensity of humoral immune response

Leptospirosis severity may be increasing, with pulmonary involvement becoming more frequent. Does this increase result from an intense immune response to leptospire? Notice that renal failure, thrombocytopenia and pulmonary complications are found during the immune phase. Thirty-five hospitalized patients with Weil's disease had 5 blood samples drawn, from the 15th day to the 12th month of symptoms, for ELISA-IgM, -IgG and -IgA specific antibody detection. According their 1st IgG titer, the patients were divided into: group 1 (n = 13) titer > 1:400 (positive) and group 2 (n = 22) titer <=1:400 (negative). Early IgG antibodies in group 1 showed high avidity which may indicate reinfection. Group 1 was older, had worse pulmonary and renal function, and fever for a longer period than group 2. Throughout the study, IgG and IgA titers remained higher in group 1. In conclusion, the severity of Weil's disease may be associated with the intensity of the humoral immune response to leptospire.

Litterfall production in intact and selectively logged forests in southern of Amazonia as a function of basal area of vegetation and plant density

Nutrient recycling in the forest is linked to the production and decomposition of litter, which are essential processes for forest maintenance, especially in regions of nutritionally poor soils. Human interventions in forest such as selecttive logging may have strong impacts on these processes. The objectives of this study were to estimate litterfall production and evaluate the influence of environmental factors (basal area of vegetation, plant density, canopy cover, and soil physicochemical properties) and anthropogenic factors (post-management age and exploited basal area) on this production, in areas of intact and exploited forest in southern Amazonia, located in the northern parts of Mato Grosso state. This study was conducted at five locations and the average annual production of litterfall was 10.6 Mg ha-1 year-1, higher than the values for the Amazon rainforest. There were differences in litterfall productions between study locations. Effects of historical logging intensity on litterfall production were not significant. Effects of basal area of vegetation and tree density on litterfall production were observed, highlighting the importance of local vegetation characteristics in litterfall production. This study demonstrated areas of transition between the Amazonia-Cerrado tend to have a higher litterfall production than Cerrado and Amazonia regions, and this information is important for a better understanding of the dynamics of nutrient and carbon cycling in these transition regions.

Resistance Exercise Restores Endothelial Function and Reduces Blood Pressure in Type 1 Diabetic Rats

Background: Resistance exercise effects on cardiovascular parameters are not consistent. Objectives: The effects of resistance exercise on changes in blood glucose, blood pressure and vascular reactivity were evaluated in diabetic rats. Methods: Wistar rats were divided into three groups: control group (n = 8); sedentary diabetic (n = 8); and trained diabetic (n = 8). Resistance exercise was carried out in a squat device for rats and consisted of three sets of ten repetitions with an intensity of 50%, three times per week, for eight weeks. Changes in vascular reactivity were evaluated in superior mesenteric artery rings. Results: A significant reduction in the maximum response of acetylcholine-induced relaxation was observed in the sedentary diabetic group (78.1 ± 2%) and an increase in the trained diabetic group (95 ± 3%) without changing potency. In the presence of NG-nitro-L-arginine methyl ester, the acetylcholine-induced relaxation was significantly reduced in the control and trained diabetic groups, but not in the sedentary diabetic group. Furthermore, a significant increase (p < 0.05) in mean arterial blood pressure was observed in the sedentary diabetic group (104.9 ± 5 to 126.7 ± 5 mmHg) as compared to that in the control group. However, the trained diabetic group showed a significant decrease (p < 0.05) in the mean arterial blood pressure levels (126.7 ± 5 to 105.1 ± 4 mmHg) as compared to the sedentary diabetic group. Conclusions: Resistance exercise could restore endothelial function and prevent an increase in arterial blood pressure in type 1 diabetic rats.

Parenteral administration of vitamins A, D and E on the oxidative metabolism and function of polymorphonuclear leukocytes in swine

The weaning period of piglets is characterized by physiological alterations, such as decreased weight gain, increased reactive oxygen species (ROS) and increased serum cortisol levels with possible effects on the immune response. The effect of parenteral administration of vitamins A, D and E on production performance, oxidative metabolism, and the function of polymorphonuclear leukocytes (PMNLs) was assessed in piglets during the weaning period. The sample was comprised of 20 male piglets that were given an injectable ADE vitamin combination (135,000 IU vitamin A, 40,000 IU vitamin D and 40mg vitamin E/ animal) at 20 and 40 days of age. Weight gain, concentration of reduced glutathione (GSH), malondialdehyde (MDA), superoxide dismutase (SOD) and the microbicidal and phagocytic activity of PMNLs were assessed. No difference was observed in the average piglet weight during the study; however, a greater percentage of weight gain was observed after weaning in the treated group. The concentrations of GSH and SOD did not differ between groups, although lipid peroxidation was greater in the control group at 60 days of age. The investigated variables of oxidative metabolism were correlated as follows: -0.41 for GSH and MDA, -0.54 for GSH and SOD and 0.34 for MDA and SOD. The intensity of intracellular ROS production, the percentage of ROS-producing PMNLs and the intensity of phagocytosis by PMNLs did not differ between treatment groups. Administration of the injectable ADE combination improved the percentage of weight gain between 20 and 40 days of age, decreased oxidative stress at 60 days of age and did not influence the function of PMNLs in piglets.

Photosynthetic characteristics of hybrid and conventional rice plants as a function of plant competition

The objective of this work was to evaluate the characteristics related to the photosynthetic ability of hybrid and inbred rice varieties, as a way to assess which of the two presented higher potential to stand out under conditions of competition. The trial was set in a greenhouse in completely randomized block design and 2 x 6 factorial scheme with four replications. Factor A consisted of rice varieties (hybrid or inbred) and factor B by competition levels. Treatments consisted in maintaining one plant of either BRS Pelota (inbred) or Inov (hybrid) variety at the center of the plot, under competition with 0, 1, 2, 3, 4 or 5 plants of the variety BRS Pelota at the periphery of the experimental unit, according to the treatment. Fifty days after emergence (DAE), sub-stomatal CO2 concentration (Ci - mmol mol-1), photosynthetic rate (A - mmol m-2 s-1) and CO2 consumed (DC - mmol mol-1) were quantified, as well as shoot dry mass(SDM).Hybrid plants present higher photosynthesis capacity than inbred plants, when competing with up to 3 times its own density. When under the same competitive intensity, hybrid plants surpass the inbred. However, it should be emphasized that, when in farm condition, the lower competitive capacity with weeds often attributed to the hybrid varieties, probably is due to their lower planting density, but if weed competition is kept at low levels, hybrid rice plants may perform in the same way or usually better than inbred plants.

Effect of strenuous maternal exercise before and during pregnancy on rat progeny renal function

The effects of strenuous exercise before and during pregnancy on the renal function and morphological alterations of the progeny were determined in a study on female Wistar rats. This research was done based on a previous study carried out in our laboratory, which showed morphological alterations in rats submitted to this kind of exercise. As the form is related to the function, the physiological relevance of submitting a pregnant female to a high-intensity exercise training regimen could be explained by the fact that morphological alterations can influence kidney function. The animals were assigned to one of two groups: control animals that did not exercise during pregnancy and trained animals that swam for 120 min 5 days a week for 8 weeks before pregnancy and daily for 60 min over a period of 8 weeks starting on the second day of pregnancy. Seven rats of each group were analyzed for morphological alterations and for renal function. The progeny of the rats used for morphological evaluation were born by cesarean section and the progeny of the animals used to evaluate renal function were born normally. The progeny were two months old when renal function was evaluated. Fertility and morbidity were the same for both groups. Strenuous maternal exercise had no significant influence on glomerular filtration rate (GFR) but renal plasma flow was lower in the progeny of the trained group (mean ± SD, 16.65 ± 3.77 ml min-1 kg-1) compared to the progeny of the control group (33.42 ± 2.56 ml min-1 kg-1). Antidiuretic and antinatriuretic effects on the progeny of the trained group were observed, since urine flow as percentage of GFR and the fraction of urinary sodium excretion were lower in this group (1.38 ± 0.10 and 0.60 ± 0.04%, respectively) compared to the progeny of the control group (2.36 ± 0.11 and 1.55 ± 0.20%, respectively). Moreover, in this exercise program, fetuses from trained animals were small-sized (2.45 ± 0.19 vs 4.66 ± 2.45 g for control animals) and showed lower differentiation compared to fetuses from the control group. These effects were probably caused by caloric restriction, hypoxia and reduction of umbilical cord length.

Abnormal response of left ventricular systolic function to submaximal exercise in post-partial left ventriculotomy patients

Patients with heart failure who have undergone partial left ventriculotomy improve resting left ventricular systolic function, but have limited functional capacity. We studied systolic and diastolic left ventricular function at rest and during submaximal exercise in patients with previous partial left ventriculotomy and in patients with heart failure who had not been operated, matched for maximal and submaximal exercise capacity. Nine patients with heart failure previously submitted to partial left ventriculotomy were compared with 9 patients with heart failure who had not been operated. All patients performed a cardiopulmonary exercise test with measurement of peak oxygen uptake and anaerobic threshold. Radionuclide left ventriculography was performed to analyze ejection fraction and peak filling rate at rest and during exercise at the intensity corresponding to the anaerobic threshold. Groups presented similar exercise capacity evaluated by peak oxygen uptake and at anaerobic threshold. Maximal heart rate was lower in the partial ventriculotomy group compared to the heart failure group (119 ± 20 vs 149 ± 21 bpm; P < 0.05). Ejection fraction at rest was higher in the partial ventriculotomy group as compared to the heart failure group (41 ± 12 vs 32 ± 9%; P < 0.0125); however, ejection fraction increased from rest to anaerobic threshold only in the heart failure group (partial ventriculotomy = 44 ± 17%; P = non-significant vs rest; heart failure = 39 ± 11%; P < 0.0125 vs rest; P < 0.0125 vs change in the partial ventriculotomy group). Peak filling rate was similar at rest and increased similarly in both groups at the anaerobic threshold intensity (partial ventriculotomy = 2.28 ± 0.55 EDV/s; heart failure = 2.52 ± 1.07 EDV/s; P < 0.0125; P > 0.05 vs change in partial ventriculotomy group). The abnormal responses demonstrated here may contribute to the limited exercise capacity of patients with partial left ventriculotomy despite the improvement in resting left ventricular systolic function.

A forced running wheel system with a microcontroller that provides high-intensity exercise training in an animal ischemic stroke model

We developed a forced non-electric-shock running wheel (FNESRW) system that provides rats with high-intensity exercise training using automatic exercise training patterns that are controlled by a microcontroller. The proposed system successfully makes a breakthrough in the traditional motorized running wheel to allow rats to perform high-intensity training and to enable comparisons with the treadmill at the same exercise intensity without any electric shock. A polyvinyl chloride runway with a rough rubber surface was coated on the periphery of the wheel so as to permit automatic acceleration training, and which allowed the rats to run consistently at high speeds (30 m/min for 1 h). An animal ischemic stroke model was used to validate the proposed system. FNESRW, treadmill, control, and sham groups were studied. The FNESRW and treadmill groups underwent 3 weeks of endurance running training. After 3 weeks, the experiments of middle cerebral artery occlusion, the modified neurological severity score (mNSS), an inclined plane test, and triphenyltetrazolium chloride were performed to evaluate the effectiveness of the proposed platform. The proposed platform showed that enhancement of motor function, mNSS, and infarct volumes was significantly stronger in the FNESRW group than the control group (P<0.05) and similar to the treadmill group. The experimental data demonstrated that the proposed platform can be applied to test the benefit of exercise-preconditioning-induced neuroprotection using the animal stroke model. Additional advantages of the FNESRW system include stand-alone capability, independence of subjective human adjustment, and ease of use.

Nitrogen and potassium fertilization on the yield and intensity of the maize white spot

A plant's nutritional balance can influence its resistance to diseases. In order to evaluate the effect of increasing doses of N and K on the yield and severity of the mayze white spot, two experiments were installed in the field, one in the city of Ijaci, Minas Gerais, and the other in the city of Sete Lagoas, Minas Gerais. The experimental delimitation was in randomized blocks with 5 x 5 factorial analysis of variance, and four repetitions. The treatments consisted of five doses of N (20; 40; 80; 150; 190 Kg ha-1of N in the experiments 1 and 2) and five doses of K (15; 30; 60; 120; 180 Kg ha-1of K in experiment 1 and 8.75; 17.5; 35; 50; 100 Kg ha-1of K in experiment 2). The susceptible cultivar 30P70 was planted in both experiments. The plot consisted of four rows 5 meters long, with a useful area consisting of two central rows 3 meters each. Evaluations began 43 days after emergence (DAE) in the first experiment and 56 DAE in the second one. There was no significant interaction between doses of N and K and the disease progress P+. The effect was only observed for N. The K did not influence the yield and the severity of the disease in these experiments. Bigger areas below the severity progress curve of the white spot and better yield were observed with increasing doses of N. Thus, with increasing doses of N, the white spot increased and also did the yield.

Options listing and the volatility of the underling asset: a study on the derivative market function

There are basic misunderstandings on derivative markets. Some professionals believe that they are a kind of casinos and have no utility for the investors. This work looks at the effects of options introduction in the Brazilian market, seeking for another benefit for this introduction: changes in the stocks risk leveI. Our results are the same found in the US and other markets: the options introduction reduces the stocks volatility. We also found that there is a slight indication that the volatility becames more stochastic with this alternative.

Effects of the length and timing of nighttime naps on task performance and physiological function

OBJECTIVE: To examine the effects of the length and timing of nighttime naps on performance and physiological functions, an experimental study was carried out under simulated night shift schedules. METHODS: Six students were recruited for this study that was composed of 5 experiments. Each experiment involved 3 consecutive days with one night shift (22:00-8:00) followed by daytime sleep and night sleep. The experiments had 5 conditions in which the length and timing of naps were manipulated: 0:00-1:00 (E60), 0:00-2:00 (E120), 4:00-5:00 (L60), 4:00-6:00 (L120), and no nap (No-nap). During the night shifts, participants underwent performance tests. A questionnaire on subjective fatigue and a critical flicker fusion frequency test were administered after the performance tests. Heart rate variability and rectal temperature were recorded continuously during the experiments. Polysomnography was also recorded during the nap. RESULTS: Sleep latency was shorter and sleep efficiency was higher in the nap in L60 and L120 than that in E60 and E120. Slow wave sleep in the naps in E120 and L120 was longer than that in E60 and L60. The mean reaction time in L60 became longer after the nap, and faster in E60 and E120. Earlier naps serve to counteract the decrement in performance and physiological functions during night shifts. Performance was somewhat improved by taking a 2-hour nap later in the shift, but deteriorated after a one-hour nap. CONCLUSIONS: Naps in the latter half of the night shift were superior to earlier naps in terms of sleep quality. However performance declined after a 1-hour nap taken later in the night shift due to sleep inertia. This study suggests that appropriate timing of a short nap must be carefully considered, such as a 60-min nap during the night shift.

Immunopathology of human schistosomiasis mansoni: I. Immunomodulatory influences on T cell function

Cell mediated immune response was studied in patients with recent and chronic Schistosoma mansoni infection. Precultured peripheral mononuclear cells showed significantly higher responses to S. mansoni adult worm antigen (SAWA) when compared to fresh cell preparations. The addition of each patient serum to the precultured cells reactions to SAWA or recall antigens demonstrated a strong inhibitory serum action, which was also noted on allogeneic cells derived from healthy subjects. The CD4 subset was the main responding cell to SAWA being this reactivity highly suppressed by the presence of the monocyte macrophage accessory cells. We stressed the simultaneous inhibitory action of humoral and cellular factors on the specific cell response to S. mansoni.

Labeling of Salmonella Typhymurium with iodine-131 to study phagocytic function in rats

The present study describes a method for labeling Salmonella typhymurium with iodine-131 to evaluate both the morphological and the functional characteristics of the reticulo-endothelial system. A suspension containing 2 x 10(9) bacteria per ml was labeled with carrier-free Na131I without reductor, with a labeling yield of 46.5 ± 3% and 3.5 ± 1.3% of free Iodine-131. The biodistribution of the labeled bacteria in rats was studied with a large field-of-view scintillation camera equiped with a pinhole collimator. Whole body images were obtained 15 and 30 minutes after intravenous injection of the labeled microorganisms. Images showed accumulation of bacteria in the liver and both normal and transplanted spleens of the animals. Autoradiographs of liver and spleen demonstrated labeled bacteria within the cells of the reticulo-endothelial system. The method described is easy to perform, has a good labeling yield and allows the functional evaluation of the reticulo-monophagocytic system, including transplanted spleens.

Lymphocyte subpopulations and neutrophil function in chronic human Chagas' disease

The absolute numbers of total leukocytes, lymphocytes, T cells, helper/inducer, suppressor/cytotoxic and B cells were decreased in the peripheral blood of patients with chronic Chagas' disease. Since antilymphocyte antibodies were present only in a minority of patients they probably cannot account for the abnormalities in lymphocyte subsets. Patient neutrophils stimulated with endotoxin-treated autologous plasma showed depressed chemotactic activity and this seems to be an intrinsic cellular defect rather than plasma inhibition. Random migration of neutrophils was normal. Reduction of nitroblue tetrazolium by endotoxin- stimulated neutrophils was also decreased. These findings further document the presence of immunosuppression in human Chagas' disease. They may be relevant to autoimmunity, defense against microorganisms and against tumor cells at least in a subset of patients with more severe abnormalities.