Sarcoidosis Masquerading as Atrial Fibrillation: Interesting Case Discussion as Well as Recent Advances in Diagnosis and Management of Cardiac Sarcoidosis

This report presents a case of cardiac sarcoidosis initially manifested with atrial fibrillation. This behavior is very uncommon in spite of the fact that the disease is multisystemic, affecting predominantly the lungs. It is emphasized that the diagnosis of the cardiac involvement is difficult, and when this occurs, can lead to conducting system disturbances, heart failure or sudden death (SD). The diagnosis can be made by evaluating the clinical manifestations, the noninvasive tests like ECG, Holter monitoring, chest radiography, thoracic computed tomography, magnetic resonance image and positron emission tomography. In general, sarcoidosis is treated with steroid compounds with good outcome, mainly when performed in the initial phases of the disease. Other cardiac manifestations, such as arrhythmias, atrioventricular block or heart failure, are managed similar to other cardiomyopathies.

Persistent inappropriate sinus tachycardia after radiofrequency ablation of left lateral accessory pathway

A patient with palpitations and narrow QRS tachycardia was evaluated. In the EP study an atrioventricular reentrant tachycardia mediated by a left lateral accessory pathway was identified and catheter ablation was performed with success. A week later she returned with palpitations and pre-syncope. The resting ECG showed a sinus tachycardia with 110 bpm. After unsuccessful clinical treatment with beta-blockers, diltiazem and digoxin she underwent sinus node modification using radiofrequency catheter ablation with success. We postulated that RF application to ablate the lateral accessory pathway damaged the parasympathetic innervation in the left atrioventricular groove, causing inappropriate sinus tachycardia.

Slow junctional rhythm during catheter ablation of right posteroseptal accessory pathway causing transient atrioventricular block

A male patient with palpitations and syncope during an episode of atrial fibrillation was evaluated. After DC cardioversion, the ECG showed a pattern of pre-excitation compatible with right posteroseptal bypass tract. The patient was submitted to RF. During energy application a slow junctional rhythm without AV block was noted. Twenty-four hours after the procedure AV block was observed. The AV conduction was resumed spontaneously 48 hours later with unremarkable outcome up to 1 year. We postulated that the edema caused by RF application damaged the compact AV node, causing transient AV block. The AV node lesion has been manifested by a fast junctional rhythm, but in this case we observed that even a slow junctional rhythm could do it.

Chromatin-mediated transcriptional regulation by the yeast architectural factors NHP6A and NHP6B

The Saccharomyces cerevisiae NHP6A and NHP6B proteins are chromatin architectural factors, functionally and structurally related to the mammalian high mobility group (HMG)-1 and -2 proteins, a family of non-sequence-specific DNA binding proteins. nhp6a nhp6b mutants have various morphological defects and are defective in the induced expression of several RNA polymerase II-transcribed genes. We found that NHP6A/B proteins are also required for full induction of the yeast CHA1 gene. Importantly, CHA1 basal level expression is increased 10-fold in an nhp6a nhp6b double deletion mutant. Micrococcal nuclease and DNase I analysis of the CHA1 gene in this strain showed an open promoter structure, characteristic of the activated state of this promoter, even under non-inducing conditions. To address the possible function of the NHP6A/B proteins in chromatin-mediated gene regulation, we performed whole-genome transcriptional profiling of a Deltanhp6a Deltanhp6b yeast strain. Our results suggest that NHP6A/B proteins play an important regulatory role, repressing as well as potentiating expression of genes involved in several cellular processes, and that NHP6A/B control is exerted at the level of the individual gene.

RANTES plays an important role in the evolution of allograft transplant-induced fibrous airway obliteration

Although lung transplantation is a widely applied therapeutic modality for end-stage pulmonary disease, the long-term survival following this procedure is limited by the development of bronchiolitis obliterans (BO). We investigated the role of RANTES, a C-C chemokine, in the evolution of fibrous airway obliteration (FAO) using a rat heterotopic tracheal transplant model. RANTES was highly expressed in infiltrating mononuclear cells in both allogeneic and isogeneic grafts as revealed by immunohistochemistry. Using a miniosmotic pump, neutralizing anti-RANTES antibody was locally and continuously infused to allografts, whereas recombinant rat RANTES was administered to isografts. Anti-RANTES antibody treatment decreased the number of CD4(+) infiltrating cells in allotracheas and preserved luminal patency compared with those of allocontrols. However, RANTES infusion in isografts did not induce FAO, even though CD4(+) cell migration was increased by this treatment. It appears that RANTES is relevant to the recruitment of CD4(+) cells and the development of FAO in the process of allorejection. Local administration of anti-RANTES might be a therapeutic option for BO following lung transplantation.

Transcriptional repression of the yeast CHA1 gene requires the chromatin-remodeling complex RSC

In eukaryotes, DNA is packaged into chromatin, a compact structure that must be disrupted when genes are transcribed by RNA polymerase II. For transcription to take place, chromatin is remodeled via nucleosome disruption or displacement, a fundamental transcriptional regulatory mechanism in eukaryotic organisms. Here we show that the yeast chromatin-remodeling complex, RSC (remodels the structure of chromatin), isolated on the basis of homology to the SWI/SNF complex, is required for proper transcriptional regulation and nucleosome positioning in the highly inducible CHA1 promoter. In the absence of Sth1p/Nps1p (a homolog of Swi2p/Snf2p) or of Swh3p (a homolog of Swi3p), expression of CHA1 in non-induced cells is increased to a level comparable with that of fully induced cells. Furthermore, in non-induced cells depleted for Sth1p/Nps1p or Swh3p, a nucleosome positioned over the TATA box of the CHA1 promoter is disrupted, an architectural change normally only observed during transcriptional induction. In addition, deletion of the gene-specific activator Cha4p did not affect derepression of CHA1 in cells depleted for Swh3p. Thus, CHA1 constitutes a target for the RSC complex, and we propose that RSC is essential for maintaining a repressive chromatin structure at the CHA1 promoter.

Nucleosome structure of the yeast CHA1 promoter: analysis of activation-dependent chromatin remodeling of an RNA-polymerase-II-transcribed gene in TBP and RNA pol II mutants defective in vivo in response to acidic activators

The Saccharomyces cerevisiae CHA1 gene encodes the catabolic L-serine (L-threonine) dehydratase. We have previously shown that the transcriptional activator protein Cha4p mediates serine/threonine induction of CHA1 expression. We used accessibility to micrococcal nuclease and DNase I to determine the in vivo chromatin structure of the CHA1 chromosomal locus, both in the non-induced state and upon induction. Upon activation, a precisely positioned nucleosome (nuc-1) occluding the TATA box and the transcription start site is removed. A strain devoid of Cha4p showed no chromatin alteration under inducing conditions. Five yeast TBP mutants defective in different steps in activated transcription abolished CHA1 expression, but failed to affect induction-dependent chromatin rearrangement of the promoter region. Progressive truncations of the RNA polymerase II C-terminal domain caused a progressive reduction in CHA1 transcription, but no difference in chromatin remodeling. Analysis of swi1, swi3, snf5 and snf6, as well as gcn5, ada2 and ada3 mutants, suggested that neither the SWI/SNF complex nor the ADA/GCN5 complex is involved in efficient activation and/or remodeling of the CHA1 promoter. Interestingly, in a sir4 deletion strain, repression of CHA1 is partly lost and activator-independent remodeling of nuc-1 is observed. We propose a model for CHA1 activation based on promoter remodeling through interactions of Cha4p with chromatin components other than basal factors and associated proteins.

[Catheter ablation of atrial flutter. Electrophysiological characterization of posterior and septal isthmus block]

PURPOSE

Evaluate the different types of conduction blocks obtained between inferior vena cava-tricuspid annulus (posterior isthmus) and between tricuspid annulus-coronary sinus ostium (septal isthmus) after radiofrequency (RF) catheter ablation of atrial flutter (AFL).

METHODS

In 16 procedures, 14 patients (pts), 9 male, with type I AFL underwent RF ablation. Atrial activation around tricuspid annulus was performed with a 10-bipole "Halo" catheter (H1-2; H19-20). In sinus rhythm, isthmus conduction was evaluated during proximal coronary sinus (PCS) and low lateral right atrium (H1-2) pacing, before and after linear ablation. According to the wave front of impulse propagation we assessed absence of block (bidirectional conduction); incomplete block (bidirectional conduction with delay in one front of impulse propagation) and complete block (absence of conduction). The PCS/H1-2 interval was measured before and after ablation.

RESULTS

Complete isthmus block was achieved in 7 (44%) and incomplete block in 4 (25%) procedures. Conduction block was not achieved in 5 procedures. At a mean follow-up of 12 months, there were no recurrences in the pts with complete block, whereas AFL recurred in the 6 pts with incomplete or no conduction block (p < 0.001). Pts with complete block had delta PCS/H1-2 interval (74.0 +/- 26.0 ms) greater than incomplete (30.5 +/- 7.5 ms) or absent block (p < 0.05).

CONCLUSION

The verification of complete isthmus conduction block with atrial multipolar mapping is an effective strategy to assess electrophysiological success and absence of late recurrence in common atrial flutter ablation.

Datin, a yeast poly(dA:dT)-binding protein, behaves as an activator of the wild-type ILV1 promoter and interacts synergistically with Reb1p

A cis-acting element required for GCN4-independent basal-level transcription of ILV1 was previously identified in our laboratories as a binding site for the REB1 protein (Reb1p). Further deletion analysis of the ILV1 promoter region identified a second element also required for GCN4-independent basal-level ILV1 expression. This second element is an A.T-rich tract (26 As out of 32 nucleotides) situated 15 bp downstream of the Reb1p-binding site. Deletion of both the Reblp site and the poly(dA:dT) element totally eliminates basal activity of the ILV1 promoter. We show that the two elements act synergistically to control ILV1 expression and that the synergistic effect is distance dependent. We demonstrate that (i) datin (Dat1p), the only known poly (dA:dT)-binding protein in yeast, specifically binds to the ILV1 poly(dA:dT) element in vitro; (ii) Dat1p functions as a trans-activating factor in the ILV1 context; and (iii) the synergistic activation observed in vivo between the Reb1p site and the poly(dA:dT) element depends on the presence of the structural gene for Dat1p, DAT1.

[El Nino in Borbon, Ecuador]

The "global" climatic phenomenon of El Niño is described in its "local" expressions and dramatic health implications through the daily chronicle of what happens in an area of the Pacific Amazonia in Ecuador. The report is also an example of how health promoters living with the communities substantially contribute to the comprehensive surveillance of the life, and not only of the health, of micro-populations, which is the characteristics of community epidemiology.