Effects of combustion-derived ultrafine particles and manufactured nanoparticles on heart cells in vitro

Evidence from epidemiological studies indicates that acute exposure to airborne pollutants is associated with an increased risk of morbidity and mortality attributed to cardiovascular diseases. The present study investigated the effects of combustion-derived ultrafine particles (diesel exhaust particles) as well as engineered nanoparticles (titanium dioxide and single-walled carbon nanotubes) on impulse conduction characteristics, myofibrillar structure and the formation of reactive oxygen species in patterned growth strands of neonatal rat ventricular cardiomyocytes in vitro. Diesel exhaust particles as well as titanium dioxide nanoparticles showed the most pronounced effects. We observed a dose-dependent change in heart cell function, an increase in reactive oxygen species and, for titanium dioxide, we also found a less organized myofibrillar structure. The mildest effects were observed for single-walled carbon nanotubes, for which no clear dose-dependent alterations of theta and dV/dt(max) could be determined. In addition, there was no increase in oxidative stress and no change in the myofibrillar structure. These results suggest that diesel exhaust as well as titanium dioxide particles and to a lesser extent also single-walled carbon nanotubes can directly induce cardiac cell damage and can affect the function of the cells.

Cardiac tissue engineering by electrical stimulation with subcutaneous and cardiac adipose-tissue derived progenitor cells (ATDPCs)

A major challenge of cardiac tissue engineering is directing cells to establish the physiological structure and function of the myocardium being replaced. In native heart, pacing cells generate electrical stimuli that spread throughout the heartcausing cell membrane depolarization and activation of contractile apparatus. We ought to examine whether electricalstimulation of adipose tissue-derived progenitor cells (ATDPCs) exerts phenotypic and genetic changes that enhance theircardiomyogenic potential.

Identification and characterization of a RING zinc finger gene (C-RZF) expressed in chicken embryo cells.

To identify changes in gene expression that occur in chicken embryo brain (CEB) cells as a consequence of their binding to the extracellular matrix molecule cytotactin/tenascin (CT/TN), a subtractive hybridization cloning strategy was employed. One of the cDNA clones identified was predicted to encode 381 amino acids and although it did not resemble any known sequences in the nucleic acid or protein data bases, it did contain the sequence motif for the cysteine-rich C3HC4 type of zinc finger, also known as a RING-finger. This sequence was therefore designated the chicken-RING zinc finger (C-RZF). In addition to the RING-finger, the C-RZF sequence also contained motifs for a leucine zipper, a nuclear localization signal, and a stretch of acidic amino acids similar to the activation domains of some transcription factors. Southern analysis suggested that C-RZF is encoded by a single gene. Northern and in situ hybridization analyses of E8 chicken embryo tissues indicated that expression of the C-RZF gene was restricted primarily to brain and heart. Western analysis of the nuclear and cytoplasmic fractions of chicken embryo heart cells and immunofluorescent staining of chicken embryo cardiocytes with anti-C-RZF antibodies demonstrated that the C-RZF protein was present in the nucleus. The data suggest that we have identified another member of the RING-finger family of proteins whose expression in CEB cells may be affected by CT/TN and whose nuclear localization and sequence motifs predict a DNA-binding function in the nucleus.

Iron chelating-mediated antioxidant activity of Plectranthus barbatus extract on mitochondria

Plectranthus barbatus Andrews (Lamiaceae) is a popular medicinal plant used to treat gastrointestinal and hepatic ailments. In this work, we assessed the antioxidant activity of the aqueous extract of P. barbatus leaves on Fe(2+)-citrate-mediated membrane lipid peroxidation in isolated rat liver mitochondria, as well in non-mitochondrial systems: DPPH reduction, (center dot)OH scavenging activity, and iron chelation by prevention of formation of the Fe(2+)-bathophenanthroline disulfonic acid (BPS) complex. Within all the tested concentrations (15-75 mu g/ml), P. barbatus extract presented significant free radical-scavenging activity (IC(50) = 35.8 +/- 0.27 mu g/ml in the DPPH: assay and IC(50) = 69.1 +/- 0.73 mu g/ml in the (center dot)OH assay) and chelated iron (IC(50) = 30.4 +/- 3.31 mu g/ml). Over the same concentration range, the plant extract protected mitochondria against Fe(2+)/citrate-mediated swelling and malondialdehyde production, a property that persisted even after simulation of its passage through the digestive tract. These effects could be attributed to the phenolic compounds, nepetoidin - caffeic acid esters, present in the extract. Therefore, P. barbatus extract prevents mitochondrial membrane lipid peroxidation, probably by chelation of iron, revealing potential applicability as a therapeutic source of molecules against diseases involving mitochondrial iron overload. (C) 2010 Elsevier Ltd. All rights reserved.

EVI antibodies in patients with Chagas' disease: relationship with anti-Trypanosoma cruzi immunoglobulins and effects of specific treatment

Antibodies against heart vascular structures and striated muscle cells interstitium (EVI antibodies) persist in Chagas' disease patients who had been cured by specific treatment as demonstrated by negative xenodiagnosis, conventional serology (CS) and complement mediated lysis (CoML). On the other hand, EVI antibodies are either present or absent in treated patients presenting positive CS but negative CoML. Since CoML detects antibodies associated to resistance, EVI antibodies are not likely to participate in the control of T. cruzi infections although they might be induced by cross-reacting antigens of heart cells and the parasite. They are neither necessarily related to antibodies responsible for CS. Absorption with T. cruzi and heart tissue confirms the suggestion that EVI antibodies are induced by a number of antigenic determinants, most from heart structures with a minor participation of T. cruzi antigens.

Exercise preconditioning modulates genotoxicity induced by doxorubicin in multiple organs of rats

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

The neuranatomical basis of central control of cardiorespiratory interactions in vertebrates

It seems that a dual location for vagal preganglionic neurones (VPNs) has important functional correlates in all vertebrates. This may be particularly the case with the central control exerted over the heart by cardiac VPNs (CVPNs). About 30 % of VPNs but up to 70 % of CVPNs are in the nucleus ambiguus (NA) of mammals. There is a similar proportional representation of VPNs between the major vagal nuclei in amphibians and turtles but in fish and crocodilians; the proportion of VPNs in the NA is closer to 10% and in some lizards and birds it is about 5%. However, the CVPNs are distributed unequally between these nuclei so that 45 % of the CVPNs are located in the NA of the dogfish, and about 30% in the NA of Xenopus and the duck. This topographical separation of CVPNs seems to be of importance in the central control of the heart. Cells in one location may show respiration-related activity (e.g those in the dorsal vagal nucleus (DVN) of dogfish and in the NA of mammals) while cells in the other locations do not. Their different activities and separate functions will be determined by their different afferent inputs from the periphery or from elsewhere in the CNS, which in turn will relate to their central topography. Thus, CVPNs in the NA of mammals receive inhibitory inputs from neighbouring inspiratory neurones, causing respiratory sinus arrythmia (RSA), and the CVPNs in the DVN of the dogfish may generate cardiorespiratory synchrony (CRS).

DNA damage and nitric oxide synthesis in experimentally infected Balb/c mice with Trypanosoma cruzi

This study aimed to evaluate whether experimental Chagas disease in acute phase under benznidazole therapy can cause DNA damage in peripheral blood, liver, heart, and spleen cells or induce nitric oxide synthesis in spleen cells. Twenty Balb/c mice were distributed into four groups: control (non-infected animals); Trypanosoma cruzi infected; T. cruzi infected and submitted to benznidazole therapy; and only treated with benznidazole. The results obtained with the single cell gel (comet) assay showed that T. cruzi was able induce DNA damage in heart cells of both benznidazole treated or untreated infected mice. Similarly, T. cruzi infected animals showed an increase of DNA lesions in spleen cells. Regarding nitric oxide synthesis, statistically significant differences (p < 0.05) were observed in all experimental groups compared to negative control, the strongest effect observed in the T. cruzi infected group. Taken together, these results indicate that T. cruzi may increase the level of DNA damage in mice heart and spleen cells. Probably, nitric oxide plays an important role in DNA damaging whereas benznidazole was able to minimize induced T. cruzi genotoxic effects in spleen cells. © 2006 Elsevier Inc. All rights reserved.

O isoflurano e a associação remifentanil e isoflurano usados após isquemia reperfusão causa proteção renal em ratos?

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Free, long-chain, polyunsaturated fatty acids reduce membrane electrical excitability in neonatal rat cardiac myocytes.

Because previous studies showed that polyunsaturated fatty acids can reduce the contraction rate of spontaneously beating heart cells and have antiarrhythmic effects, we examined the effects of the fatty acids on the electrophysiology of the cardiac cycle in isolated neonatal rat cardiac myocytes. Exposure of cardiomyocytes to 10 microM eicosapentaenoic acid for 2-5 min markedly increased the strength of the depolarizing current required to elicit an action potential (from 18.0 +/- 2.4 pA to 26.8 +/- 2.7 pA, P < 0.01) and the cycle length of excitability (from 525 ms to 1225 ms, delta = 700 +/- 212, P < 0.05). These changes were due to an increase in the threshold for action potential (from -52 mV to -43 mV, delta = 9 +/- 3, P < 0.05) and a more negative resting membrane potential (from -52 mV to -57 mV, delta = 5 +/- 1, P < 0.05). There was a progressive prolongation of intervals between spontaneous action potentials and a slowed rate of phase 4 depolarization. Other polyunsaturated fatty acids--including docosahexaenoic acid, linolenic acid, linoleic acid, arachidonic acid, and its nonmetabolizable analog eicosatetraynoic acid, but neither the monounsaturated oleic acid nor the saturated stearic acid--had similar effects. The effects of the fatty acids could be reversed by washing with fatty acid-free bovine serum albumin. These results show that free polyunsaturated fatty acids can reduce membrane electrical excitability of heart cells and provide an electrophysiological basis for the antiarrhythmic effects of these fatty acids.

PDIA3, HSPA5 and viementin, proteins identified by 2-DE in the valvular tissue, are the target antigens of peripheral and heart infiltrating T cells from chronic rheumatic heart disease patients

Rheumatic fever (RF) is a post-infectious autoimmune disease due to sequel of group A streptococcus (GAS) pharyngitis. Rheumatic heart disease (RHD), the major manifestation of RF, is characterized by inflammation of heart valves and myocardium. Molecular mimicry between GAS antigens and host proteins has been shown at B and T cell level. However the identification of the autoantigens recognized by B and T cells within the inflammatory microenvironment of heart tissue in patients with RHD is still incompletely elucidated. In the present study, we used two-dimensional gel electrophoresis (2-DE) and mass spectrometry to identify valvular tissue proteins target of T cells from chronic RHD patients. We could identify three proteins recognized by heart infiltrating and peripheral T cells as protein disulfide isomerase ER-60 precursor (PDIA3), 78 kD glucose-regulated protein precursor (HSPA5) and vimentin, with coverage of 45%, 43 and 34%, respectively. These proteins were recognized in a proliferation assay by peripheral and heart infiltrating T cells from RHD patients suggesting that they may be involved in the autoimmune reactions that leads to valve damage. We also observed that several other proteins isolated by 2-DE but not identified by mass spectrometry were also recognized by T cells. The identified cardiac proteins are likely relevant antigens involved in T cell-mediated autoimmune responses in RF/RHD that may contribute to the development of RHD

Trypanosoma cruzi: parasite antigens sequestered in heart interstitial dendritic cells are related to persisting myocarditis in benznidazole-treated mice

We investigated whether sequestered Trypanosoma cruzi antigens found in heart interstitial dendritic cells (IDCs) contribute to the residual myocarditis found in mice following treatment with benznidazole, a specific chemotherapeutic drug. IDCs are antigen-presenting cells that are MHC-II-receptor dependent. Swiss mice were divided into two experimental groups: the 1st group was infected with the Colombian strain of T. cruzi, which is resistant to treatment with benznidazole, and the 2nd group was infected with clone 21SF-C 3, which has a medium susceptibility to the drug. Treatment of the Colombian strain group started on the 120th day post-infection and for the 21SF-C3 strain group treatment was started on the 90th day. In both groups, treatment lasted for 90 days. The animals were sacrificed either 150 or 200 days post-treatment. The myocardium was analysed by immunohistochemistry using anti-MAC3, 33D1, CD11b and CD11c monoclonal antibodies for IDCs or anti-T. cruzi purified antibodies. Parasite antigens were expressed on the IDC membranes in both treated and untreated mice. Myocarditis subsided following treatment, evidenced by both histological and morphometrical evaluation. A reduction in the number of IDCs carrying T. cruzi antigens in the treated group indicates that the elimination of parasites influences antigen presentation with concomitant decreases in inflammation. There is a correlation between the presence of T. cruzi antigens in these cells and the chronic focal, residual myocarditis seen in treated mice.