Blood Meal-Derived Heme Decreases ROS Levels in the Midgut of Aedes aegypti and Allows Proliferation of Intestinal Microbiota

The presence of bacteria in the midgut of mosquitoes antagonizes infectious agents, such as Dengue and Plasmodium, acting as a negative factor in the vectorial competence of the mosquito. Therefore, knowledge of the molecular mechanisms involved in the control of midgut microbiota could help in the development of new tools to reduce transmission. We hypothesized that toxic reactive oxygen species (ROS) generated by epithelial cells control bacterial growth in the midgut of Aedes aegypti, the vector of Yellow fever and Dengue viruses. We show that ROS are continuously present in the midgut of sugar-fed (SF) mosquitoes and a blood-meal immediately decreased ROS through a mechanism involving heme-mediated activation of PKC. This event occurred in parallel with an expansion of gut bacteria. Treatment of sugar-fed mosquitoes with increased concentrations of heme led to a dose dependent decrease in ROS levels and a consequent increase in midgut endogenous bacteria. In addition, gene silencing of dual oxidase (Duox) reduced ROS levels and also increased gut flora. Using a model of bacterial oral infection in the gut, we show that the absence of ROS resulted in decreased mosquito resistance to infection, increased midgut epithelial damage, transcriptional modulation of immune-related genes and mortality. As heme is a pro-oxidant molecule released in large amounts upon hemoglobin degradation, oxidative killing of bacteria in the gut would represent a burden to the insect, thereby creating an extra oxidative challenge to the mosquito. We propose that a controlled decrease in ROS levels in the midgut of Aedes aegypti is an adaptation to compensate for the ingestion of heme.

Inhibition of phospholipase A(2) in rat brain decreases the levels of total Tau protein

The microtubule-associated protein Tau promotes the assembly and stability of microtubules in neuronal cells. Six Tau isoforms are expressed in adult human brain. All six isoforms become abnormally hyperphosphorylated and form neurofibrillary tangles in Alzheimer disease (AD) brains. In AD, reduced activity of phospholipase A(2) (PLA(2)), specifically of calcium-dependent cytosolic PLA(2) (cPLA(2)) and calcium-independent intracellular PLA(2) (iPLA(2)), was reported in the cerebral cortex and hippocampus, which positively correlated with the density of neurofibrillary tangles. We previously demonstrated that treatment of cultured neurons with a dual cPLA(2) and iPLA(2) inhibitor, methyl arachidonyl fluorophosphonate (MAFP), decreased total Tau levels and increased Tau phosphorylation at Ser(214) site. The aim of this study was to conduct a preliminary investigation into the effects of in vivo infusion of MAFP into rat brain on PLA(2) activity and total Tau levels in the postmortem frontal cortex and dorsal hippocampus. PLA(2) activity was measured by radioenzymatic assay and Tau levels were determined by Western blotting using the anti-Tau 6 isoforms antibody. MAFP significantly inhibited PLA(2) activity in the frontal cortex and hippocampus. The reactivity to the antibody revealed three Tau protein bands with apparent molecular weight of close to 40, 43 and 46 kDa in both brain areas. MAFP decreased the 46 kDa band intensity in the frontal cortex, and the 43 and 46 kDa band intensities in the hippocampus. The results indicate that in vivo PLA(2) inhibition in rat brain decreases the levels of total (nonphosphorylated plus phosphorylated) Tau protein and corroborate our previous in vitro findings.

Dialysis water treated by reverse osmosis decreases the levels of C-reactive protein in uremic patients

Atherosclerosis is a major complication of chronic renal failure. Microinflammation is involved in atherogenesis and is associated with uremia and dialysis. The role of dialysate water contamination in inducing inflammation has been debated. Our aim was to study inflammatory markers in patients on chronic dialysis, before and 3 to 6 months after switching the water purification system from deionization to reverse osmosis. Patients had demographic, clinical and nutritional information collected and blood drawn for determination of albumin, ferritin, C-reactive protein (CRP), interleukin-6, and tumor necrosis factor-alpha in both situations. Acceptable levels of water purity were less than 200 colony-forming units of bacteria and less than 1 ng/ml of endotoxin. Sixteen patients died. They had higher median CRP (26.6 vs 11.2 mg/dl, P = 0.007) and lower median albumin levels (3.1 vs 3.9 g/l, P < 0.05) compared to the 31 survivors. Eight patients were excluded because of obvious inflammatory conditions. From the 23 remaining patients (mean age ± SD: 51.3 ± 13.9 years), 18 had a decrease in CRP after the water treatment system was changed. Overall, median CRP was lower with reverse osmosis than with deionization (13.2 vs 4.5 mg/l, P = 0.022, N = 23). There was no difference in albumin, cytokines, subjective global evaluation, or clinical and biochemical parameters. In conclusion, uremic patients presented a clinically significant reduction in CRP levels when dialysate water purification system switched from deionization to reverse osmosis. It is possible that better water treatments induce less inflammation and eventually less atherosclerosis in hemodialysis patients.

Prolonged Physical Training Decreases mRNA Levels of Glucocorticoid Receptor and Inflammatory Genes

Background/Aims: Prolonged physical exercise induces adaptive alterations in the hypothalamic-pituitary axis, increasing cortisol metabolism, and reducing cortisol synthesis and glucocorticoid sensitivity. The mechanisms responsible for this relative glucocorticoid resistance remain unknown but may involve expression of genes encoding glucocorticoid receptor (GR) and/or inflammatory molecules of nuclear factor kappa B1 (NFkB1) signaling pathway and cytokines. This study aimed to determine the impact of prolonged physical training on the expression of genes involved in glucocorticoid action and inflammatory response. Methods: Normal sedentary male cadets of the Brazilian Air Force Academy were submitted to 6 weeks of standardized physical training. Eighteen of 29 initially selected cadets were able to fully complete the training program. Fasting glucose, insulin and cortisol levels, cytokine concentration and the expression of genes encoding GR, NFkB1, inhibitor of NFkB1 and IkB kinase A were determined before and after the training period. Results: Prolonged physical exercise reduced the basal cortisol levels and the percent cortisol reduction after dexamethasone. These findings were associated with a significant reduction in the mRNA levels of GR (6.3%), NFkB1 (63%), inhibitor of NFkB1 (25%) and IkB kinase A (46%) with concomitant reduction in cytokine concentrations (ELISA). Conclusions: Prolonged physical training decreases the glucocorticoid sensitivity and the mRNA levels of the GR gene combined with decreased mRNA of genes related to the NFkB pathway. Copyright (C) 2010 S. Karger AG, Basel

Environmental enrichment blocks ethanol-induced locomotor sensitization and decreases BDNF levels in the prefrontal cortex in mice

The use of addictive drugs can lead to long-term neuroplastic changes in the brain, including behavioral sensitization, a phenomenon related to addiction. Environmental enrichment (EE) is a strategy used to study the effect of environment on the response to several manipulations, including treatment with addictive drugs. Brain-derived neurotrophic factor (BDNF) has been associated with behaviors related to ethanol addiction. The aim of the present study was to evaluate the effects of EE on ethanol-induced behavioral sensitization and BDNF expression. Mice were exposed to EE and then repeatedly treated with a low dose (1.8 g/kg) of ethanol. Another group of mice was first subjected to repeated ethanol treatment according to the behavioral sensitization protocol and then exposed to EE. Environmental enrichment prevented the development of ethanol-induced behavioral sensitization and blocked behavioral sensitization in sensitized mice. Both repeated ethanol and EE decreased BDNF levels in the prefrontal cortex but not in the hippocampus. However, BDNF levels were lower in ethanol-treated mice exposed to EE. These findings suggest that EE can act on the mechanisms implicated in behavioral sensitization, a model for drug-induced neuroplasticity and relapse. Additionally, EE alters BDNF levels, which regulate addiction-related behaviors.

Perfil lipídico e fatores biológicos e ambientais : o papel da atividade física

RESUMO - Introdução: A inatividade física é um dos determinantes major das doenças crónicas não transmissíveis sendo a quarta maior causa de mortalidade no mundo, nomeadamente para as doenças vasculares. A prática regular de atividade física produz adaptações vasculares responsáveis por efeitos benéficos na prevenção e tratamento dos diferentes fatores de risco vascular, nomeadamente através do seu efeito no metabolismo das lipoproteínas. Objetivos: Analisar a interferência da atividade física no perfil lipídico de uma população residente em Portugal. Métodos: Estudo observacional descritivo transversal exploratório com 1027 indivíduos (idade: 18 aos 80 anos, 49% mulheres). Os dados foram analisados em SPSS (versão 20), tendo-se utilizado métodos de estatística descritiva e de análise bivariável entre os factores de risco vascular e as variáveis do perfil lipídico e ainda uma análise multivariável de regressão logística binária para medir a razão de riscos pelo odds ratio. O nível de significância foi estabelecido em 5%. Resultados: Na análise da relação entre atividade física e os biomarcadores do perfil lipídico verificou-se que existem benefícios no que diz respeito ao aumento dos níveis de HDL e de apoA1 e na diminuição dos níveis de TG com a prática regular de atividade física. Conclusões: A atividade física apresenta um papel importante na regulação do perfil lipídico evidenciando a necessidade de implementar estratégias multissectoriais de prevenção dos fatores de risco vascular, nomeadamente na área dos estilos de vida saudáveis que são fundamentais para a prevenção destas condições de saúde e para gerar ganhos em saúde.

The effect of treatment on the age-antibody relationship in children infected with Schistosoma mansoni and Schistosoma haematobium

The effect of praziquantel treatment on the age-antibody relationship was studied in 174 children aged between 6 and 17 years from a schistosome endemic area in Zimbabwe. The children were co-infected with Schistosoma mansoni and S. haematobium with infection prevalences of 74% and 53% respectively. Antibody levels for the isotypes IgA, IgE, IgM, IgG1, IgG2, IgG3 and IgG4, directed against soluble egg antigen were measured using an indirect ELISA assay. Treatment resulted in a significant increase in levels of IgG2 and IgG3 while levels of IgA decreased significantly. In untreated children there were significant decreases in levels of IgG4. Treatment also resulted in significant alteration in the age-antibody profiles for the isotypes IgE, IgM, IgG1 and IgG2 in treated children but not in untreated children. The results are discussed in the context of factors believed to give rise to the age-antibody relationship; i.e. age-related exposure patterns, age-related development of acquired immunity, age-related hormonal changes and age-related changes in innate susceptibility to infection.

Hyperglycemia downregulates Connexin36 in pancreatic islets via the upregulation of ICER-1/ICER-1γ.

Channels formed by the gap junction protein Connexin36 (CX36) contribute to the proper control of insulin secretion. We previously demonstrated that chronic exposure to glucose decreases Cx36 levels in insulin-secreting cells in vitro. Here, we investigated whether hyperglycemia also regulates Cx36 in vivo. Using a model of continuous glucose infusion in adult rats, we showed that prolonged (24-48 h) hyperglycemia reduced the Cx36 gene Gjd2 mRNA levels in pancreatic islets. Accordingly, prolonged exposure to high glucose concentrations also reduced the expression and function of Cx36 in the rat insulin-producing INS-1E cell line. The glucose effect was blocked after inhibition of the cAMP/PKA pathway and was associated with an overexpression of the inducible cAMP early repressor ICER-1/ICER-1γ, which binds to a functional cAMP-response element in the promoter of the Cx36 gene Gjd2. The involvement of this repressor was further demonstrated using an antisense strategy of ICER-1 inhibition, which prevented glucose-induced downregulation of Cx36. The data indicate that chronic exposure to glucose alters the in vivo expression of Cx36 by the insulin-producing β-cells through ICER-1/ICER-1γ overexpression. This mechanism may contribute to the reduced glucose sensitivity and altered insulin secretion, which contribute to the pathophysiology of diabetes.

Effects of pioglitazone on renal calcium excretion.

Context: Glitazones increase fracture risk in long-term users and in postmenopausal women. Studies have demonstrated deleterious effects of glitazones on bone metabolism. Glitazones also have direct renal tubular effects increasing sodium reabsorption. We hypothesized that glitazones may also regulate renal calcium excretion. Design: In this double-blind, randomized, placebo-controlled, four-way, crossover study, we examined the effects of pioglitazone (45 mg/d for 6 wk) or placebo on renal calcium and phosphate excretion and PTH levels during different sodium intakes in 16 individuals (eight with type 2 diabetes and eight with essential hypertension). Results: Pioglitazone had no effect on corrected plasma calcium and phosphate levels but decreased significantly the alkaline phosphatase and PTH levels. Pioglitazone induced on average a 45% increase in urinary calcium excretion. The fractional excretion of calcium rose to the same extent, suggesting a glomerular filtration rate-independent effect. Sodium intake did not influence the calciuric effect of pioglitazone. Changes in diurnal and nocturnal calciuria were similar. There was no effect of pioglitazone on phosphate excretion. Conclusion: Pioglitazone decreases PTH levels and increases urinary calcium excretion, independently from changes in glomerular filtration rate and from the sodium load, suggesting an inhibitory effect of pioglitazone on the tubular reabsorption of calcium. These effects may contribute to the increased fracture risk with glitazone treatment.

Cardiovascular, respiratory and metabolic responses to temperature and hypoxia of the winter frog Rana catesbeiana

The objective of the present study was to determine the effects of hypoxia and temperature on the cardiovascular and respiratory systems and plasma glucose levels of the winter bullfrog Rana catesbeiana. Body temperature was maintained at 10, 15, 25 and 35oC for measurements of breathing frequency, heart rate, arterial blood pressure, metabolic rate, plasma glucose levels, blood gases and acid-base status. Reducing body temperature from 35 to 10oC decreased (P<0.001) heart rate (bpm) from 64.0 ± 3.1 (N = 5) to 12.5 ± 2.5 (N = 6) and blood pressure (mmHg) (P<0.05) from 41.9 ± 2.1 (N = 5) to 33.1 ± 2.1 (N = 6), whereas no significant changes were observed under hypoxia. Hypoxia-induced changes in breathing frequency and acid-base status were proportional to body temperature, being pronounced at 25oC, less so at 15oC, and absent at 10oC. Hypoxia at 35oC was lethal. Under normoxia, plasma glucose concentration (mg/dl) decreased (P<0.01) from 53.0 ± 3.4 (N = 6) to 35.9 ± 1.7 (N = 6) at body temperatures of 35 and 10oC, respectively. Hypoxia had no significant effect on plasma glucose concentration at 10 and 15oC, but at 25oC there was a significant increase under conditions of 3% inspired O2. The arterial PO2 and pH values were similar to those reported in previous studies on non-estivating Rana catesbeiana, but PaCO2 (37.5 ± 1.9 mmHg, N = 5) was 3-fold higher, indicating increased plasma bicarbonate levels. The estivating bullfrog may be exposed not only to low temperatures but also to hypoxia. These animals show temperature-dependent responses that may be beneficial since during low body temperatures the sensitivity of most physiological systems to hypoxia is reduced

Incidence, risk factors and prognostic factors of acute renal failure in patients admitted to an intensive care unit

The objective of the present study was to assess the incidence, risk factors and outcome of patients who develop acute renal failure (ARF) in intensive care units. In this prospective observational study, 221 patients with a 48-h minimum stay, 18-year-old minimum age and absence of overt acute or chronic renal failure were included. Exclusion criteria were organ donors and renal transplantation patients. ARF was defined as a creatinine level above 1.5 mg/dL. Statistics were performed using Pearsons' chi2 test, Student t-test, and Wilcoxon test. Multivariate analysis was run using all variables with P < 0.1 in the univariate analysis. ARF developed in 19.0% of the patients, with 76.19% resulting in death. Main risk factors (univariate analysis) were: higher intra-operative hydration and bleeding, higher death risk by APACHE II score, logist organ dysfunction system on the first day, mechanical ventilation, shock due to systemic inflammatory response syndrome (SIRS)/sepsis, noradrenaline use, and plasma creatinine and urea levels on admission. Heart rate on admission (OR = 1.023 (1.002-1.044)), male gender (OR = 4.275 (1.340-13642)), shock due to SIRS/sepsis (OR = 8.590 (2.710-27.229)), higher intra-operative hydration (OR = 1.002 (1.000-1004)), and plasma urea on admission (OR = 1.012 (0.980-1044)) remained significant (multivariate analysis). The mortality risk factors (univariate analysis) were shock due to SIRS/sepsis, mechanical ventilation, blood stream infection, potassium and bicarbonate levels. Only potassium levels remained significant (P = 0.037). In conclusion, ARF has a high incidence, morbidity and mortality when it occurs in intensive care unit. There is a very close association with hemodynamic status and multiple organ dysfunction.

Comparative effects of organic and inorganic mercury on in vivo dopamine release in freely moving rats

The present study was carried out in order to compare the effects of administration of organic (methylmercury, MeHg) and inorganic (mercury chloride, HgCl 2 ) forms of mercury on in vivo dopamine (DA) release from rat striatum. Experiments were performed in conscious and freely moving female adult Sprague-Dawley (230-280 g) rats using brain microdialysis coupled to HPLC with electrochemical detection. Perfusion of different concentrations of MeHg or HgCl 2 (2 µL/min for 1 h, N = 5-7/group) into the striatum produced significant increases in the levels of DA. Infusion of 40 µM, 400 µM, or 4 mM MeHg increased DA levels to 907 ± 31, 2324 ± 156, and 9032 ± 70% of basal levels, respectively. The same concentrations of HgCl 2 increased DA levels to 1240 ± 66, 2500 ± 424, and 2658 ± 337% of basal levels, respectively. These increases were associated with significant decreases in levels of dihydroxyphenylacetic acid and homovallinic acid. Intrastriatal administration of MeHg induced a sharp concentration-dependent increase in DA levels with a peak 30 min after injection, whereas HgCl 2 induced a gradual, lower (for 4 mM) and delayed increase in DA levels (75 min after the beginning of perfusion). Comparing the neurochemical profile of the two mercury derivatives to induce increases in DA levels, we observed that the time-course of these increases induced by both mercurials was different and the effect produced by HgCl 2 was not concentration-dependent (the effect was the same for the concentrations of 400 µM and 4 mM HgCl 2 ). These results indicate that HgCl 2 produces increases in extracellular DA levels by a mechanism differing from that of MeHg.

Efecto del estrés ocasionado por las pruebas académicas sobre los niveles de cortisol y prolactina en un grupo de estudiantes de Medicina

Introducción: La relación entre el sistema inmune y el estrés ha sido motivo de debate en los últimos años. Los cambios neurohormonales generan variaciones en la respuesta inmunológica, con cambios importantes en los niveles de citoquinas lo que causa a su vez, en algunos casos, depresión de la respuesta citotóxica debida a la disminución de la población de células asesinas naturales (NK) (1). El estrés académico constituye un buen modelo para estudiar los cambios asociados en la secreción de algunas hormonas del eje Hipotalámico- Pituitario-Adrenocortical -HPA- (2, 3). Materiales y métodos: En el presente estudio se evaluó el comportamiento de las hormonascortisol y prolactina, así como su incidencia en la respuesta adaptativa a Herpes Simple tipo I, en una población de estudio constituída por 26 estudiantes de la Facultad de Medicina, con edades comprendidas entre 14 y 27 años, con mayor frecuencia de género masculino (80.8%). Se realizó un estudio de intervención longitudinal en tres momentos, donde se midieron los niveles de cortisol, prolactina y anticuerpos contra Herpes Simple tipo I. Así mismo, se realizó una medición 15 días antes de la exposición al estresor, durante la aplicación del estresor (semana de exámenes trimestrales), y quince días después de la exposición al estresor Todas las muestras fueron tomadas entre las 8:00 a.m. y las 10:00 a.m. Resultados y discusión: Se encontraron diferencias significativas (p < 0.001) en los valores promedio de prolactina, pues hubo una tendencia secular al aumento en los tres momentos evaluados. Para el cortisol, los cambios estuvieron cerca de mostrar diferencias significativas (p = 0.098), con un aumento en el momento del estresor y una disminución después del estresor. También hubo diferencias significativas (p = 0.043) en los niveles de anticuerpos para Herpes Simple tipo I, con una tendencia secular al aumento en los tres momentos evaluados. La respuesta adaptativa a Herpes Simple tipo I aumentó notoriamente como resultado de los cambios en la concentración de prolactina, la que, a su vez, aumentó de manera significativa después de la exposición al estresor. Aunque los niveles de cortisol no aumentan significativamente durante la semana del estresor, podrían ser suficientes para mantener niveles basales de prolactina, sin que haya un aumento de la respuesta adaptativa. Se podría inferir que el cortisol regula la síntesis de prolactina, pues en los resultados se observa que, a medida que disminuye la concentración de cortisol, los niveles de prolactina aumentan significativamente.

Calcium gluconate and sodium succinate for therapy of sodium fluoroacetate experimental intoxication in cats: clinical and electrocardiographic evaluation

Sodium fluoroacetate (SFAC) or Compound 1080 is a potent rodenticide, largely used after 1946 for rodent and home pest control. The toxic effects of SFAC are caused by fluorocitrate action, a toxic metabolite, which has a competitive action with aconitase enzyme, leading to citrate accumulation and resulting in interference in energy production by Krebs cycle blockade. In the present study, domestic cats were intoxicated with oral doses of fluoroacetate (0.45 mg/kg). The intoxicated animals presented emesis, diarrhea with abdominal pain posture and an abdominal palpation, tachypnea, bilateral midriasis, hypothermia, hyperexcitability and convulsions. Blood gas analysis indicated decreased pH and bicarbonate levels. Serum ionized calcium was also decreased. ECG showed non-specific changes in ventricular repolarization and ventricular arrhythmias. The survival rate was 75% in the treated group with calcium gluconate and sodium succinate and 37.5% in the non-treated group.