Cucurbitacin I Inhibits Cell Motility by Indirectly Interfering with Actin Dynamics

Cucurbitacins are plant natural products that inhibit activation of the Janus kinase 2 (JAK2)/signal transducer and activator of transcription 3 (STAT3) pathway by an unknown mechanism. They are also known to cause changes in the organization of the actin cytoskeleton. actin depolymerization experiments, cucurbitacin I had no effect on the rate of actin filament disassembly at the nanomolar concentrations that inhibit cell migration. At elevated concentrations, the depolymerization rate was also unaffected, although there was a delay in the initiation of depolymerization. Therefore, cucurbitacin I targets some factor involved in cellular actin dynamics other than actin itself. Two candidate proteins that play roles in actin depolymerization are the actin-severing proteins cofilin and gelsolin. Cucurbitacin I possesses electrophilic reactivity that may lead to chemical modification of its target protein, as suggested by structure-activity relationship data. However, mass spectrometry revealed no evidence for modification of purified cofilin or gelsolin by cucurbitacin I.Cucurbitacin I results in accumulation of actin filaments in cells by a unique indirect mechanism. Furthermore, the proximal target of cucurbitacin I relevant to cell migration is unlikely to be the same one involved in activation of the JAK2/STAT3 pathway

Complex SUMO-1 Regulation of Cardiac Transcription Factor Nkx2-5

Reversible post-translational protein modifications such as SUMOylation add complexity to cardiac transcriptional regulation. The homeodomain transcription factor Nkx2-5/Csx is essential for heart specification and morphogenesis. It has been previously suggested that SUMOylation of lysine 51 (K51) of Nkx2-5 is essential for its DNA binding and transcriptional activation. Here, we confirm that SUMOylation strongly enhances Nkx2-5 transcriptional activity and that residue K51 of Nkx2-5 is a SUMOylation target. However, in a range of cultured cell lines we find that a point mutation of K51 to arginine (K51R) does not affect Nkx2-5 activity or DNA binding, suggesting the existence of additional Nkx2-5 SUMOylated residues. Using biochemical assays, we demonstrate that Nkx2-5 is SUMOylated on at least one additional site, and this is the predominant site in cardiac cells. The second site is either non-canonical or a “shifting” site, as mutation of predicted consensus sites and indeed every individual lysine in the context of the K51R mutation failed to impair Nkx2-5 transcriptional synergism with SUMO, or its nuclear localization and DNA binding. We also observe SUMOylation of Nkx2-5 cofactors, which may be critical to Nkx2-5 regulation. Our data reveal highly complex regulatory mechanisms driven by SUMOylation to modulate Nkx2-5 activity

Critical Slow Conduction Zone Located between the Tricuspid Annulus and a Myocardial Infarct Scar in a Patient with Multiple Ventricular Tachycardia Late after Myocardial Infarction

A patient underwent an electrophysiological study (EPS) and catheter ablation (CA) for ventricular tachycardia (VT) that developed 11 years after myocardial infarction. Entrainment mapping (EM) of the left ventricle did not identify the origin of the VT during induction. Electro-anatomical mapping revealed a low voltage area from the anterior to the inferior left ventricular wall. Another EPS was performed for right ventricular mapping. A basket catheter was placed in the right ventricle to evaluate impulse propagation and we attempted to identify the VT circuit with EM during the same VT (complete left bundle branch block configuration, inferior axis) as the previous EPS. Eight different VT appeared, three of which were sustained during CA. The reentry circuit exit was identified on the tricuspid annulus (TA) at the 9:00 site and radiofrequency (RF) ablation was performed, but the axis transformed from the inferior to the superior and another VT appeared. Despite RF ablation to the VT circuit exit at the 5:00 site, another sustained VT appeared. Finally, it was terminated by ablation to a critical slow conduction zone (SCZ) located near the 7:00 site one year later. Electro-anatomical voltage mapping detected a critical isthmus between TA and right ventricle infarct scar. Here, we describe a rare SCZ proximal to the TA in a patient with VT late after myocardial infarction

Lead Extractions are not Necessarily Required in the Treatment of Cases with Local Complications Unproven Resional/systemic Infection at the Pacemaker/ implantable Cardioverter Defibrillator (ICD) Site

Introduction: In a case of pacemaker and/or implantable cardioverter defibrillator (ICD) implantations, there is the possibility of infections related to the device. In such case, the removal of the total system is desirable, however, the lead extraction can sometimes be difficult. Methods: Among 756 subjects who underwent a device implantation procedure, we experienced 19 cases with a device infection or skin problems requiring a surgical procedure such as thinning or inflammation of the skin over the pocket or lead. We divided these 19 cases into three groups as cases with neither systemic nor local infections (N group), cases with regional but systemic infections (R group), and cases with systemic infections (S group). And the prognoses of these cases were investigated. Results: Out of the 19 cases, 12 cases were classified into N group, 5 cases were classified into R group, and the remaining 2 cases were classified into S group. The lead extractions were performed in one case each in the N, R and S groups. None of the cases in the N group developed a systemic infection over an average observation period of 31 months. Four cases in the R group remain been free from systemic infection over an average observation period of 39.5 months. Conclusion: Lead extractions are the ideal treatment in cases with device implantation site complications, but are not necessary if the extraction is difficult

Confiabilidade do diagnóstico final de dengue na epidemia 2001-2002 no Município do Rio de Janeiro, Brasil Reliability of the final dengue diagnosis in the epidemic occurring in Rio de Janeiro, Brazil, 2001-2002

Este estudo analisou a confiabilidade do diagnóstico final das 155.242 notificações de dengue da epidemia 2001-2002 no Município do Rio de Janeiro, fornecidas pela Secretaria Municipal de Saúde do Rio de Janeiro, por meio do Sistema de Informação de Agravos de Notificação (SINAN). O diagnóstico final possui como opções de preenchimento: dengue clássico, febre hemorrágica do dengue, descartado, inconclusivo e ignorado. Foi construída uma rotina em Epi Info para comparar o diagnóstico final digitado no SINAN com os critérios do Ministério da Saúde (MS), agrupando os casos como dengue clássico, dengue hemorrágico, descartado e inconclusivo (inclui ignorado). O diagnóstico final mostrou 52,4% dengue clássico, 0,6% dengue hemorrágico, 0,9% descartado e 46% de inconclusivo e ignorado, sendo que 78% de dengue clássico, 69% de dengue hemorrágico e 21,1% dos descartados preencheram os critérios do MS. A confiabilidade do diagnóstico final digitado foi em geral satisfatória (kappa = 0,681; IC95%: 0,685-0,677), porém baixa para os óbitos (kappa = 0,152; IC95%: 0,046-0,258). Considerando-se o volume da epidemia, o diagnóstico final de dengue clássico e dengue hemorrágico foi satisfatório, porém a alta proporção de casos ignorados e inconclusivos e a baixa qualidade da informação nos óbitos limitam o uso do SINAN nesse contexto.<br>This study analyzed the reliability of the final diagnosis in the 155,242 dengue reports during the 2001-2002 epidemic in the city of Rio de Janeiro, Brazil, using the official information system on communicable diseases (SINAN). The system allows the following options for the final diagnosis: classic dengue, dengue hemorrhagic fever, discarded, inconclusive, and unknown. We built a classification routine in Epi Info to compare the final diagnosis from SINAN with Ministry of Health criteria. According to the final diagnosis, the case breakdown was: 52.4% classic dengue; 0.6% dengue hemorrhagic fever; 0.9% discarded; 46% inconclusive and unknown. The revised diagnosis showed that 78% of classic dengue, 69% of dengue hemorrhagic fever, and 21.1% of discarded cases met the classification criteria. Although the reliability of the SINAN final diagnosis was generally satisfactory (kappa = 0.681; 95%CI: 0.685-0.677), it was worse for fatal cases (kappa = 0.152; 95%CI: 0.046-0.258). Considering the epidemic's magnitude, the final diagnosis of classic dengue and dengue hemorrhagic fever was satisfactory, but the high proportion of inconclusive or unknown cases and the poor quality of information for fatal cases limit the usefulness of SINAN in this context