The Impact of Heterozygous KCNK3 Mutations Associated With Pulmonary Arterial Hypertension on Channel Function and Pharmacological Recovery

Background-Heterozygous loss of function mutations in the KCNK3 gene cause hereditary pulmonary arterial hypertension (PAH). KCNK3 encodes an acid-sensitive potassium channel, which contributes to the resting potential of human pulmonary artery smooth muscle cells. KCNK3 is widely expressed in the body, and dimerizes with other KCNK3 subunits, or the closely related, acid-sensitive KCNK9 channel. Methods and Results-We engineered homomeric and heterodimeric mutant and nonmutant KCNK3 channels associated with PAH. Using whole-cell patch-clamp electrophysiology in human pulmonary artery smooth muscle and COS7 cell lines, we determined that homomeric and heterodimeric mutant channels in heterozygous KCNK3 conditions lead to mutation-specific severity of channel dysfunction. Both wildtype and mutant KCNK3 channels were activated by ONO-RS-082 (10 mu mol/L), causing cell hyperpolarization. We observed robust gene expression of KCNK3 in healthy and familial PAH patient lungs, but no quantifiable expression of KCNK9, and demonstrated in functional studies that KCNK9 minimizes the impact of select KCNK3 mutations when the 2 channel subunits co-assemble. Conclusions-Heterozygous KCNK3 mutations in PAH lead to variable loss of channel function via distinct mechanisms. Homomeric and heterodimeric mutant KCNK3 channels represent novel therapeutic substrates in PAH. Pharmacological and pH-dependent activation of wildtype and mutant KCNK3 channels in pulmonary artery smooth muscle cells leads to membrane hyperpolarization. Co-assembly of KCNK3 with KCNK9 subunits may provide protection against KCNK3 loss of function in tissues where both KCNK9 and KCNK3 are expressed, contributing to the lung-specific phenotype observed clinically in patients with PAH because of KCNK3 mutations.National Heart, Lung, and Blood Institute (NHLBI)Cardiovascular Medical Research and Education Fund (CMREF)Columbia Univ, Coll Phys & Surg, Dept Pharmacol, New York, NY USAColumbia Univ, Dept Pediat, Coll Phys & Surg, New York, NY 10027 USAUniv Fed São Paulo, Paulista Sch Med, Dept Biophys, São Paulo, BrazilNew York Stem Cell Fdn, Res Inst, New York, NY USAUniv Fed São Paulo, Paulista Sch Med, Dept Biophys, São Paulo, BrazilNHLBI: F30 HL129656NHLBI R24 grant: R24HL123767Web of Scienc

Photography-based taxonomy is inadequate, unnecessary, and potentially harmful for biological sciences

The question whether taxonomic descriptions naming new animal species without type specimen(s) deposited in collections should be accepted for publication by scientific journals and allowed by the Code has already been discussed in Zootaxa (Dubois & Nemésio 2007; Donegan 2008, 2009; Nemésio 2009a–b; Dubois 2009; Gentile & Snell 2009; Minelli 2009; Cianferoni & Bartolozzi 2016; Amorim et al. 2016). This question was again raised in a letter supported by 35 signatories published in the journal Nature (Pape et al. 2016) on 15 September 2016. On 25 September 2016, the following rebuttal (strictly limited to 300 words as per the editorial rules of Nature) was submitted to Nature, which on 18 October 2016 refused to publish it. As we think this problem is a very important one for zoological taxonomy, this text is published here exactly as submitted to Nature, followed by the list of the 493 taxonomists and collection-based researchers who signed it in the short time span from 20 September to 6 October 2016

Evolving trends in the management of acute appendicitis during COVID-19 waves. The ACIE appy II study

Background: In 2020, ACIE Appy study showed that COVID-19 pandemic heavily affected the management of patients with acute appendicitis (AA) worldwide, with an increased rate of non-operative management (NOM) strategies and a trend toward open surgery due to concern of virus transmission by laparoscopy and controversial recommendations on this issue. The aim of this study was to survey again the same group of surgeons to assess if any difference in management attitudes of AA had occurred in the later stages of the outbreak. Methods: From August 15 to September 30, 2021, an online questionnaire was sent to all 709 participants of the ACIE Appy study. The questionnaire included questions on personal protective equipment (PPE), local policies and screening for SARS-CoV-2 infection, NOM, surgical approach and disease presentations in 2021. The results were compared with the results from the previous study. Results: A total of 476 answers were collected (response rate 67.1%). Screening policies were significatively improved with most patients screened regardless of symptoms (89.5% vs. 37.4%) with PCR and antigenic test as the preferred test (74.1% vs. 26.3%). More patients tested positive before surgery and commercial systems were the preferred ones to filter smoke plumes during laparoscopy. Laparoscopic appendicectomy was the first option in the treatment of AA, with a declined use of NOM. Conclusion: Management of AA has improved in the last waves of pandemic. Increased evidence regarding SARS-COV-2 infection along with a timely healthcare systems response has been translated into tailored attitudes and a better care for patients with AA worldwide

Genetic mechanisms of critical illness in COVID-19.

Host-mediated lung inflammation is present1, and drives mortality2, in the critical illness caused by coronavirus disease 2019 (COVID-19). Host genetic variants associated with critical illness may identify mechanistic targets for therapeutic development3. Here we report the results of the GenOMICC (Genetics Of Mortality In Critical Care) genome-wide association study in 2,244 critically ill patients with COVID-19 from 208 UK intensive care units. We have identified and replicated the following new genome-wide significant associations: on chromosome 12q24.13 (rs10735079, P = 1.65 × 10-8) in a gene cluster that encodes antiviral restriction enzyme activators (OAS1, OAS2 and OAS3); on chromosome 19p13.2 (rs74956615, P = 2.3 × 10-8) near the gene that encodes tyrosine kinase 2 (TYK2); on chromosome 19p13.3 (rs2109069, P = 3.98 ×  10-12) within the gene that encodes dipeptidyl peptidase 9 (DPP9); and on chromosome 21q22.1 (rs2236757, P = 4.99 × 10-8) in the interferon receptor gene IFNAR2. We identified potential targets for repurposing of licensed medications: using Mendelian randomization, we found evidence that low expression of IFNAR2, or high expression of TYK2, are associated with life-threatening disease; and transcriptome-wide association in lung tissue revealed that high expression of the monocyte-macrophage chemotactic receptor CCR2 is associated with severe COVID-19. Our results identify robust genetic signals relating to key host antiviral defence mechanisms and mediators of inflammatory organ damage in COVID-19. Both mechanisms may be amenable to targeted treatment with existing drugs. However, large-scale randomized clinical trials will be essential before any change to clinical practice

Global burden of 288 causes of death and life expectancy decomposition in 204 countries and territories and 811 subnational locations, 1990–2021: a systematic analysis for the Global Burden of Disease Study 2021

BACKGROUND Regular, detailed reporting on population health by underlying cause of death is fundamental for public health decision making. Cause-specific estimates of mortality and the subsequent effects on life expectancy worldwide are valuable metrics to gauge progress in reducing mortality rates. These estimates are particularly important following large-scale mortality spikes, such as the COVID-19 pandemic. When systematically analysed, mortality rates and life expectancy allow comparisons of the consequences of causes of death globally and over time, providing a nuanced understanding of the effect of these causes on global populations. METHODS The Global Burden of Diseases, Injuries, and Risk Factors Study (GBD) 2021 cause-of-death analysis estimated mortality and years of life lost (YLLs) from 288 causes of death by age-sex-location-year in 204 countries and territories and 811 subnational locations for each year from 1990 until 2021. The analysis used 56 604 data sources, including data from vital registration and verbal autopsy as well as surveys, censuses, surveillance systems, and cancer registries, among others. As with previous GBD rounds, cause-specific death rates for most causes were estimated using the Cause of Death Ensemble model-a modelling tool developed for GBD to assess the out-of-sample predictive validity of different statistical models and covariate permutations and combine those results to produce cause-specific mortality estimates-with alternative strategies adapted to model causes with insufficient data, substantial changes in reporting over the study period, or unusual epidemiology. YLLs were computed as the product of the number of deaths for each cause-age-sex-location-year and the standard life expectancy at each age. As part of the modelling process, uncertainty intervals (UIs) were generated using the 2·5th and 97·5th percentiles from a 1000-draw distribution for each metric. We decomposed life expectancy by cause of death, location, and year to show cause-specific effects on life expectancy from 1990 to 2021. We also used the coefficient of variation and the fraction of population affected by 90% of deaths to highlight concentrations of mortality. Findings are reported in counts and age-standardised rates. Methodological improvements for cause-of-death estimates in GBD 2021 include the expansion of under-5-years age group to include four new age groups, enhanced methods to account for stochastic variation of sparse data, and the inclusion of COVID-19 and other pandemic-related mortality-which includes excess mortality associated with the pandemic, excluding COVID-19, lower respiratory infections, measles, malaria, and pertussis. For this analysis, 199 new country-years of vital registration cause-of-death data, 5 country-years of surveillance data, 21 country-years of verbal autopsy data, and 94 country-years of other data types were added to those used in previous GBD rounds. FINDINGS The leading causes of age-standardised deaths globally were the same in 2019 as they were in 1990; in descending order, these were, ischaemic heart disease, stroke, chronic obstructive pulmonary disease, and lower respiratory infections. In 2021, however, COVID-19 replaced stroke as the second-leading age-standardised cause of death, with 94·0 deaths (95% UI 89·2-100·0) per 100 000 population. The COVID-19 pandemic shifted the rankings of the leading five causes, lowering stroke to the third-leading and chronic obstructive pulmonary disease to the fourth-leading position. In 2021, the highest age-standardised death rates from COVID-19 occurred in sub-Saharan Africa (271·0 deaths [250·1-290·7] per 100 000 population) and Latin America and the Caribbean (195·4 deaths [182·1-211·4] per 100 000 population). The lowest age-standardised death rates from COVID-19 were in the high-income super-region (48·1 deaths [47·4-48·8] per 100 000 population) and southeast Asia, east Asia, and Oceania (23·2 deaths [16·3-37·2] per 100 000 population). Globally, life expectancy steadily improved between 1990 and 2019 for 18 of the 22 investigated causes. Decomposition of global and regional life expectancy showed the positive effect that reductions in deaths from enteric infections, lower respiratory infections, stroke, and neonatal deaths, among others have contributed to improved survival over the study period. However, a net reduction of 1·6 years occurred in global life expectancy between 2019 and 2021, primarily due to increased death rates from COVID-19 and other pandemic-related mortality. Life expectancy was highly variable between super-regions over the study period, with southeast Asia, east Asia, and Oceania gaining 8·3 years (6·7-9·9) overall, while having the smallest reduction in life expectancy due to COVID-19 (0·4 years). The largest reduction in life expectancy due to COVID-19 occurred in Latin America and the Caribbean (3·6 years). Additionally, 53 of the 288 causes of death were highly concentrated in locations with less than 50% of the global population as of 2021, and these causes of death became progressively more concentrated since 1990, when only 44 causes showed this pattern. The concentration phenomenon is discussed heuristically with respect to enteric and lower respiratory infections, malaria, HIV/AIDS, neonatal disorders, tuberculosis, and measles. INTERPRETATION Long-standing gains in life expectancy and reductions in many of the leading causes of death have been disrupted by the COVID-19 pandemic, the adverse effects of which were spread unevenly among populations. Despite the pandemic, there has been continued progress in combatting several notable causes of death, leading to improved global life expectancy over the study period. Each of the seven GBD super-regions showed an overall improvement from 1990 and 2021, obscuring the negative effect in the years of the pandemic. Additionally, our findings regarding regional variation in causes of death driving increases in life expectancy hold clear policy utility. Analyses of shifting mortality trends reveal that several causes, once widespread globally, are now increasingly concentrated geographically. These changes in mortality concentration, alongside further investigation of changing risks, interventions, and relevant policy, present an important opportunity to deepen our understanding of mortality-reduction strategies. Examining patterns in mortality concentration might reveal areas where successful public health interventions have been implemented. Translating these successes to locations where certain causes of death remain entrenched can inform policies that work to improve life expectancy for people everywhere. FUNDING Bill & Melinda Gates Foundation

Disfunção cardíaca em animal nocaute para o receptor do tipo 2 para bradicinina

Exportado OPUSMade available in DSpace on 2019-08-14T06:13:15Z (GMT). No. of bitstreams: 1 resumo_dissertacao_final_danilo_roman_campos.pdf: 10717 bytes, checksum: 638edd174dfc15bf575670f127e3702b (MD5) Previous issue date: 16As bradicininas são importantes peptídeos moduladores da função cardiovascular. Elas atuam através da ativação de dois distintos receptores, receptores do tipo 1 e 2, denominados B1R e B2R. Esses receptores são acoplados a proteína G, ativando vias de sinalização intracelular. O papel que ambos desempenham na fisiologia cardíaca ainda é pouco conhecido. Por este motivo, decidimos estudar o animal nocaute para o B2R (B2R-/-), para averiguarmos o papel que este desempenha no controle da função cardíaca. Utilizando a técnica de Langendorff foi caracterizada uma redução na capacidade contrátil do coração isolado. Para melhor investigarmos os mecanismos envolvidos na disfunção cardíaca, estudamos os miócitos cardíacos isolados. Foi constatado que a capacidade contrátil, tanto de células isoladas do ventrículo direito como do esquerdo, apresentou redução significativa, bem como aumento no tempo para 50% da contração e relaxamento. Para caracterizarmos as propriedades elétricas das células isoladas do ventrículo esquerdo utilizamos a técnica de patch-clamp nos modos current- e voltage-clamp e foi constatado que, comparando-se o controle com o B2R-/- o potencial de ação apresenta uma duração maior; o potencial de repouso encontra-se mais despolarizado; a corrente de potássio retificadora de entrada (IK1) não está alterada; a corrente de potássio transiente de saída (Ito) encontra-se reduzida; a corrente de potássio retificadora de saída (Ik) não foi alterada e a corrente de cálcio do tipo L (ICa,L) foi atenuada. Além disso, os processos cinéticos da Ito e ICa,L foram, de uma forma geral, alterados. Avaliamos a liberação de Ca2+ pelo retículo sarcoplasmático através da técnica de microscopia confocal e constatamos que animais B2R-/- apresentam uma liberação fracional reduzida de Ca2+. Para caracterizarmos alterações na produção de espécies reativas do oxigênio avaliamos a produção basal de superóxido pelos cardiomiócitos e constatamos que os animais B2R-/- apresentam uma produção basal aumentada, quando comparados com os animais controle. Também averiguamos a participação do óxido nítrico (NO) na modulação da Ito, ICa,L e do transiente global de Ca2+. Constatamos que o NO é, em parte, responsável pela redução da Ito e ICa,L nos cardiomiócitos de animais B2R-/-, porém o NO não é responsável pela redução observada do transiente global de Ca2+. Tomando em conjunto, nossos dados indicam que os animais B2R-/- apresentam uma redução importante na função cardíaca, sendo este fenótipo devido, em parte, às alterações na eletrofisiologia das células cardíacas, na redução da liberação de Ca2+ dos estoques intracelulares (retículo sarcoplasmático) e no aumento da produção de superóxido. Além disso, as alterações encontradas devem-se provavelmente, a uma produção aumentada de óxido nítrico. Em suma, o fenótipo cardíaco apresentado pelos animais B2R-/- assemelha-se àquele encontrado na insuficiência cardíaca, indicando que os camundongos B2R-/- desenvolvem naturalmente esta patologia.The Kinins are important peptides concerning control of cardiovascular function. Their action mechanism depend on the activation of two distinct receptor, type 1 and 2 bradykinin receptor (B1R and B2R). They both are coupled to G protein, which are responsible to activate different intracellular pathways, involved in different cellular process. Their role in the control of heart function is not well understood. Based on this issue, we decided to evaluate the heart physiology of mouse knockout to type 2 receptor of bradykinin (B2R-/-), in order to evaluate the B2R function in the heart physiology. Using langendorff technique we observed a reduced heart function, in terms of contraction. To evaluate the mechanism involved in the heart dysfunction, we used isolated cardiomyocyte. We evaluated the cellular contraction and both, left and right ventricular cardiomyocytes presented reduction in cell shorthening. Furthermore, time to 50% to contraction and relaxation were increased. In order to investigate the electrical properties of left ventricular cardiomyocyte in B2R-/-, we used patch-clamp technique in current and voltage-clamp mode. When comparing control and B2R-/- we observed: increased time to repolarization of action potential; increased resting potential; inward potassium rectification (IK1) is not altered; transient outward potassium current (Ito) was reduced; delay potassium current (Ik) was not altered and L-type calcium current (ICa,L) was attenuated. Besides, kinetics process concerning Ito and ICa,L, in a overall mean were altered. We evaluated calcium release from sarcoplasmatic reticulum using confocal microscope and we obtained a reduction in calcium release from sarcoplasmatic reticulum from B2R-/-. To characterize alterations in the production of reactive oxygen species we evaluate basal production of superoxide in cardiomyocyte and B2R-/- presented an increased production when comparing to control. We also investigated the participation of nitric oxide (NO) in modulate Ito, ICa,L and calcium release from sarcoplasmatic reticulum. We observed that NO is, in parts, responsible to the reduction in Ito and ICa,L in cardiomyocytes of B2R-/-. However NO is not responsible to the reduction in calcium transient. Taking together, our results indicate that B2R-/- mice present a reduction in heart function attributed to alterations in electrophysiology, calcium transient and generation of reactive oxygen species. Furthermore, the dysfunction presented is, in parts, due to excessive production of NO. In sum, the heart phenotype presented by B2R-/- mice is similar to many models of heart failure, indicating that B2R-/- mice develop spontaneous heart failure

Alterações eletromecânicas do miócito cardíaco na fase aguda da doença de Chagas em modelo murino: papel do óxido nítrico, intereferon-gama e ânion superóxido

Exportado OPUSMade available in DSpace on 2019-08-13T21:32:09Z (GMT). No. of bitstreams: 1 tese_final_danilo_roman_campos.pdf: 9188705 bytes, checksum: 74ba7f1c281bfb52331d6961fe51b9cc (MD5) Previous issue date: 4A cardiopatia chásica, causada pelo Trypanosoma cruzi, possui múltipla origem, sendo ainda desconhecida a gênese do problema cardíaco decorrente dessa doença. A fisiopatologia da doença de Chagas pode ser dividida em duas fases, aguda e crônica. Na fase aguda ocorre uma grande expansão do número de parasitos, com ativação do sistema imune e indução de uma intensa miocardite. Essas alterações podem induzir a arritmias complexas, e levar à morte. A despeito desses fatores, pouco se conhece sobre a gênese dos problemas cardíacos durante a infecção pelo Trypanosoma cruzi. Por esse motivo, decidimos estudar a fase aguda da doença de Chagas em modelo murino, bem como avaliar a influência da cepa no estabelecimento da cardiopatia. A curva de parasitemia dos animais infectados com a cepa colombiana apresentou um caráter transitório, sendo que com 81 dias pós-infecção (dpi), já não foram mais detectados parasitos na circulação. A produção de MCP-1, IFN-g e TNF-a seguiu um perfil similar ao da curva de parasitemia, sendo observada uma inflamação crônica aos 170 dpi. A infecção causou um aumento na duração do completo QRS, bem como alternância de onda P e complexo QRS, com aumento da freqüência cardíaca. Também foi observado hipertrofia cardíaca aos 30 dpi. Já aos 15 dpi, a ecocardiografia evidenciou uma redução na funcionalidade do coração. Adicionalmente a capacidade contrátil do miócito foi atenuada tanto no ventrículo direito quanto no esquerdo (VD e VE), aos 15, 30 e 45 dpi. Os resultados eletrocardiográficos evidenciaram que existe um remodelamento da eletrofisiologia do miócito cardíaco. Por esse motivo caracterizamos diferentes componentes iônicos dos VE e VD. Tanto para o VD quanto para o VE com 15 dpi, observamos uma redução na corrente de cálcio do tipo L (ICa,L), porém sem alteração no tempo necessário para repolarização do potencial de ação (PA) no VE. Considerando-se apenas o VE, a corrente de potássio transiente rápida (Ito) e o retificador de entrada (IK1) não foram alterados. Contudo, tanto o VE quanto o VD apresentaram uma redução na ICa,L e Ito aos 30 dpi, bem como um aumento no tempo necessário para repolarização do PA, seguido de um aumento, apenas no VE, da IK1. Além disso, observamos que a produção basal de óxido nítrico em células do VE de animais aos 30 dpi encontra-se aumentada e a inibição dessa produção resultou em um recobro da ICa,L. Adicionalmente, a inibição de um passo upstream na via, a PI3Kinase, também recuperou parcialmente a ICa,L. Também estudamos a dinâmica intracelular de cálcio do VE em animais aos 30 dpi. Observamos, contudo, que não existe uma redução na liberação transiente de cálcio, bem como em seu estoque intracelular do íon. A manutenção da liberação de cálcio foi observada mesmo com um aumento do tempo para o pico do transiente e da recaptura de cálcio, além de ter sido observado um desacoplamento entre o receptor de rianodina e o canal de cálcio do tipo L. Além disso, a freqüência e a amplitude das sparks de cálcio não foram alteradas, fato que indica que outros mecanismos estão envolvidos no controle do receptor de rianodina durante a infecção. Uma via envolvida na redução da capacidade contrátil do VE é a do IFN-g. Quando avaliamos o encurtamento celular do miócito isolado do animal IFN-g-/- com 15 e 26-28 dpi, o VE apresentou função contrátil similar à do controle. Entretanto, o VD do camundongo IFN-g-/- infectado apresentou uma atenuação no encurtamento celular, maior do que a observada no animal controle infectado, indicando que o VD e o VE são modulados por vias distintas. Os parâmetros avaliados nos animais infectados com a cepa Y apresentaram resultados bem distintos daqueles observados nos infectados com a cepa colombina. Quando avaliamos a funcionalidade do coração, observamos uma redução parcial e transitória da função cardíaca, sem, contudo, ocorrência de hipertrofia. Os animais infectados com a cepa Y apresentaram uma alteração transitória das propriedades elétricas dos miócitos isolados do ventrículo esquerdo, sendo que foi observada atenuação nos 15 e 30 dpi, com recobro dos valores aos 45 dpi. Aos 15 dpi ocorreu um aumento do tempo para repolarização do PA, redução da Ito e redução da ICa,L. Essas alterações não foram mais observadas com 45 dpi. Os mecanismos envolvidos na modulação negativa dessas correntes aos 15 dpi envolvem a produção de superóxido produzida pela nicotinamida e adenina fosfato oxidase do tipo 2, já que quando utilizamos o animal knockout para essa enzima não observamos as alterações relatadas acima. Finalmente, observamos que uma redução na atividade colinérgica do coração não é capaz de gerar as alterações elétricas observadas em nosso estudo. Sendo assim, nossos resultados sugerem que o estabelecimento de uma fase cardíaca crônica manifesta ou não na doença de Chagas, irá depender da cepa, sendo que essa irá determinar uma miocardite crônica ou transitória.Cardiomyopathy observed during infection by the flagellated protozoan Trypanosoma cruzi has unknown mechanism concerning your genesis. Chagas disease is separated in two distinct phases, acute and chronic. In the acute phase it is observed a large number of parasites on blood stream, following activation of immune system which induces severe miocarditis. These alterations in many cases could lead to occurrence of severe arrhythmias, leading to death. Despite of the great importance of Chagas disease in the Latin American, few is known about the mechanisms involved in the establishment of this disease. Based on that, we decided to evaluate the acute phase of Chagas disease in murine model, as well as the influence of strain type in the cardiomyopathy development. Following infection and control of parasitemia with colombian strain of Trypanosoma cruzi, after 81 days, it was not possible to find parasites in the blood stream. The production of MCP-1, IFN-g and TNF-a followed a similar profile of parasitemia curve, however it was possible to see a chronic inflammation at 170 days post-infection (dpi). At first we evaluated the electrocardiogram at 30 dpi. The infection caused an increased in the QRS interval, besides a P wave and QRS complex alternance, with increased heart frequency. Additionally, we observed heart hypertrophy and reduced heart performance at 30 and 15 dpi, respectively, as determined by echocardiography. When we evaluated the isolated cardiomyocyte function, by the shortening index, it was observed a significant reduction in cardiomyocyte shortening at 15, 30 and 45 dpi, in the left and right ventricles (LV and RV). Taking into account the electrocardiographic results, it is possible to realize that there is an electrical remodeling in isolated cardiomyocyte. Thus, we decided to determinate the cellular basis of this phenomenon. In the LV and RV, at 15 dpi we observed a reduced L-type calcium current (ICa,L). In the LV, at 15 dpi, we did not observe any change in the action potential (AP), inward potassium current (IK1) and transient outward fast potassium current (Ito). However, at 30 dpi, in the LV and RV we observed a reduced ICa,L, Ito and an increased time to AP repolarization, as well as and increased in IK1, only in the LV. Besides, we demonstrated that LV has an increased production of nitric oxide at 30 dpi, and inhibition of nitric oxide synthase recovered ICa,L in LV at 30 dpi. Additionally, upstream inhibition in this pathway, the PI3kinase, partially recovered ICa,L. Trying to better understand the molecular basis of cardiomyocyte dysfunction, we evaluated the intracellular calcium dynamics in LF at 30 dpi. However, we did not observe any reduction in calcium transient neither in the SR load. We did not observe alterations in calcium spark frequency and amplitude. In our study we postulate that LV dysfunction is determinated, at least in part, by IFN-g. LV function in isolated myocyte from IFN-g-/- was preserved at 15 and 26-28 dpi. However, RV shortening of myocyte from IFN-g-/- infected mice was reduced depend on infection time. This is an indicative that LV and RV are differentially modulated. We performed some experiments in mice infected with Y strain of Trypanosoma cruzi. Echocardiography revealed a partial and transitory reduction in heart function, however without hypertrophy. When we evaluated ICa,L, Ito and AP in LV in this group, we observed a reduction in ICa,L and Ito and an increase in AP duration at 15 dpi. However, at 30 and 45 dpi we observed either a partial or a complete recovery of all parameters studied, respectively. The mechanism(s) involved in alteration of ICa,L, Ito and AP waveform at 15 dpi was/were attributed to increased production of superoxide, since when we used knockout mice to NADPH-oxidase type 2, we did not observe any alteration . At last, we demonstrated that reduced cholinergic function in heart is not able to induce electrical remodeling basically in the same way as observed in our experimental model. Taking all together, our results demonstrate that the establishment or not of a cardiac chronic phase in Chagas disease, is dependent on Trypanosoma cruzi´s infective strain, which will determinate a chronic or transitory myocarditis

Electrical Properties of Isolated Cardiomyocytes in a Rat Model of Thiamine Deficiency

In modern society, thiamine deficiency (TD) remains an important medical condition linked to altered cardiac function. There have been contradictory reports about the impact of TD on heart physiology, especially in the context of cardiac excitability. In order to address this particular question, we used a TD rat model and patch-clamp technique to investigate the electrical properties of isolated cardiomyocytes from epicardium and endocardium. Neither cell type showed substantial differences on the action potential waveform and transient outward potassium current. Based on our results we can conclude that TD does not induce major electrical remodeling in isolated cardiac myocytes in either endocardium or epicardium cells