Valdo Silva | Universidade Federal do Triângulo Mineiro (UFTM) (original) (raw)

Papers by Valdo Silva

Sleep & breathing = Schlaf & Atmung, Jan 11, 2018

We tested the hypothesis that (i) diet associated with exercise would improve arterial baroreflex... more We tested the hypothesis that (i) diet associated with exercise would improve arterial baroreflex (ABR) control in metabolic syndrome (MetS) patients with and without obstructive sleep apnea (OSA) and (ii) the effects of this intervention would be more pronounced in patients with OSA. Forty-six MetS patients without (noOSA) and with OSA (apnea-hypopnea index, AHI > 15 events/h) were allocated to no treatment (control, C) or hypocaloric diet (- 500 kcal/day) associated with exercise (40 min, bicycle exercise, 3 times/week) for 4 months (treatment, T), resulting in four groups: noOSA-C (n = 10), OSA-C (n = 12), noOSA-T (n = 13), and OSA-T (n = 11). Muscle sympathetic nerve activity (MSNA), beat-to-beat BP, and spontaneous arterial baroreflex function of MSNA (ABR, gain and time delay) were assessed at study entry and end. No significant changes occurred in C groups. In contrast, treatment in both patients with and without OSA led to a significant decrease in weight (P < 0.05) an...

PloS one, 2016

Visceral leishmaniasis (VL) is a serious and fatal disease. Therapeutic drugs are toxic and non-s... more Visceral leishmaniasis (VL) is a serious and fatal disease. Therapeutic drugs are toxic and non-sterilizing. The etiological agents Leishmania infantum and Leishmania donovani cause active and asymptomatic diseases. Effective drugs to treat VL exist but unfortunately, post-treatment relapses are common. Little is known why drugs are non-sterilizing or how these intracellular pathogens can escape treatment. Here, using a murine model of VL we found that CD271+/Sca1+ bone marrow mesenchymal stem cells (BM-MSCs) are readily infected in vitro and in vivo by L. infantum. Because BM-MSCs express potent drug efflux pumps, e.g., ABCG2 it is possible that this unique intracellular infectious niche could allow L. infantum to escape anti-parasite drugs.

Cardiovascular research, Jan 22, 2015

bradycardic agents are currently used in the treatment of angina and heart failure; direct inform... more bradycardic agents are currently used in the treatment of angina and heart failure; direct information on their effects on cardiac sympathetic nerve activity (SNA) may be relevant to their chronic use. The present study evaluates the effect of pacemaker inhibition on SNA; direct nerve recordings and indirect autonomic indexes are compared. Experiments were performed in 18 anesthetized rats. SNA (direct nerve recording) and heart rate variability (HRV) indexes were evaluated in parallel. All parameters were recorded 10 min. before to 60 min. after administration of the If blocker ivabradine (2mg/Kg, i.v. ; n=8) or vehicle ( n=5). Ivabradine-induced RR interval (RR) prolongation (at 60 min.+15.±7.1%, p<0.01) was associated with decreased diastolic arterial pressure (DAP) (-17.3±8.4%, p<0.05) and increased SNA (+51.1±12.3%, p<0.05). These effects were accompanied by increased RR variance (RRσ(2)), which showed strong positive correlation with RR. Frequency domain HRV indexes (...

Stem Cell Research, 2015

Physical activity evokes well-known adaptations in the cardiovascular system. Although exercise t... more Physical activity evokes well-known adaptations in the cardiovascular system. Although exercise training induces cardiac remodeling, whether multipotent stem cells play a functional role in the hypertrophic process remains unknown. To evaluate this possibility, C57BL/6 mice were subjected to swimming training aimed at achieving cardiac hypertrophy, which was morphologically and electrocardiographically characterized. Subsequently, c-Kit(+)Lin(-) and Sca-1(+)Lin(-) cardiac stem cells (CSCs) were quantified using flow cytometry while cardiac muscle-derived stromal cells (CMSCs, also known as cardiac-derived mesenchymal stem cells) were assessed using in vitro colony-forming unit fibroblast assay (CFU-F). Only the number of c-Kit(+)Lin(-) cells increased in the hypertrophied heart. To investigate a possible extracardiac origin of these cells, a parabiotic eGFP transgenic/wild-type mouse model was used. The parabiotic pairs were subjected to swimming, and the wild-type heart in particular was tested for eGFP(+) stem cells. The results revealed a negligible number of extracardiac stem cells in the heart, allowing us to infer a cardiac origin for the increased amount of detected c-Kit(+) cells. In conclusion, the number of resident Sca-1(+)Lin(-) cells and CMSCs was not changed, whereas the number of c-Kit(+)Lin(-) cells was increased during physiological cardiac hypertrophy. These c-Kit(+)Lin(-) CSCs may contribute to the physiological cardiac remodeling that result from exercise training.

Frontiers in Physiology, 2015

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Revista da Sociedade Brasileira de Medicina Tropical, 2003

Mediators of Inflammation, 2014

The aim of the present study was to assess the effects of an anticholinesterase agent, pyridostig... more The aim of the present study was to assess the effects of an anticholinesterase agent, pyridostigmine bromide (Pyrido), on experimental chronic Chagas heart disease in mice. To this end, male C57BL/6J mice noninfected (control:Con) or chronically infected (5 months) withTrypanosoma cruzi(chagasic:Chg) were treated or not (NT) with Pyrido for one month. At the end of this period, electrocardiogram (ECG); cardiac autonomic function; heart histopathology; serum cytokines; and the presence of blood and tissue parasites by means of immunohistochemistry and PCR were assessed. In NT-Chg mice, significant changes in the electrocardiographic, autonomic, and cardiac histopathological profiles were observed confirming a chronic inflammatory response. Treatment with Pyrido in Chagasic mice caused a significant reduction of myocardial inflammatory infiltration, fibrosis, and hypertrophy, which was accompanied by a decrease in serum levels of IFNγwith no change in IL-10 levels, suggesting a shift...

European Journal of Applied Physiology, 2013

Previous investigations show that metabolic syndrome (MetSyn) causes sympathetic hyperactivation.... more Previous investigations show that metabolic syndrome (MetSyn) causes sympathetic hyperactivation. Symptoms of anxiety and mood disturbance (AMd) provoke sympatho-vagal imbalance. We hypothesized that AMd would alter even further the autonomic function in patients with MetSyn. Twenty-six never-treated patients with MetSyn (ATP-III) were allocated to two groups, according to the levels of anxiety and mood disturbance: (1) with AMd (MetSyn + AMd, n = 15), and (2) without AMd (MetSyn, n = 11). Ten healthy control subjects were also studied (C, n = 10). AMd was determined using quantitative questionnaires. Muscle sympathetic nerve activity (MSNA, microneurography), blood pressure (oscillometric beat-to-beat basis), and heart rate (ECG) were measured during a baseline 10-min period. Spectral analysis of RR interval and systolic arterial pressure were analyzed, and the power of low (LF) and high (HF) frequency bands were determined. Sympatho-vagal balance was obtained by LF/HF ratio. Spontaneous baroreflex sensitivity (BRS) was evaluated by calculation of α-index. MSNA was greater in patients with MetSyn + AMd compared with MetSyn and C. Patients with MetSyn + AMd showed higher LF and lower HF power compared with MetSyn and C. In addition, LF/HF balance was higher in MetSyn + AMd than in MetSyn and C groups. BRS was decreased in MetSyn + AMd compared with MetSyn and C groups. Anxiety and mood disturbance alter autonomic function in patients with MetSyn. This autonomic dysfunction may contribute to the increased cardiovascular risk observed in patients with mood alterations.

Pace-pacing and Clinical Electrophysiology, 2006

Revista da Sociedade Brasileira de Medicina Tropical, 2003

Mutation Research/Genetic Toxicology and Environmental Mutagenesis, 2008

Amiodarone, a benzofuran derivative, is a very effective antiarrhythmic medication, but has poten... more Amiodarone, a benzofuran derivative, is a very effective antiarrhythmic medication, but has potential to cause side effects. Although its cytotoxicity potential is very well-known, there are few reports about its genotoxicity effects. Since amiodarone has not been investigated in genotoxicity studies, and the spontaneously hypertensive rat (SHR) is a well-characterized model for hypertension, the aim of the present study was to perform cytogenetic analysis on chromosome aberrations in bone marrow cells of SHRs and normotensive Wistar-Kyoto rats (WKYs) that received oral amiodarone treatment for 4 weeks. Amiodarone activity was also monitored using electrocardiograms. The presence of bradycardia in amiodarone-treated rats confirmed that this drug was really active. Metaphase analysis on bone marrow cells showed that there were significant differences in total chromosomal damage and percentage abnormal metaphase between WKY and SHR negative controls. In the SHR negative control, the frequencies of basal chromosomal aberrations and abnormal metaphases were significantly higher (p&amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;lt;0.05). There were high numbers of chromosomal aberrations in all amiodarone-treated groups, compared with negative controls. In amiodarone-treated groups, the most frequent chromosomal aberration was chromatid breaks. More chromosomal aberrations were found in WKYs that received amiodarone, with a statistically significant difference in comparison with negative controls (p&amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;lt;0.05). However, in SHR rats there was no significant difference between the amiodarone and negative groups regarding chromosomal damage induction. These results showed that treatment with amiodarone was genotoxic in WKYs, but not in SHRs. Further studies are needed to confirm whether amiodarone is genotoxic or efficient and harmless, among humans undergoing therapy.