Frequency and Associated Clinical Features of Functional Tricuspid Regurgitation in Patients With Chronic Atrial Fibrillation.

Significant functional tricuspid regurgitation (TR) can develop in some but not all patients with chronic atrial fibrillation (AF). This study sought to identify factors likely to be involved in determining the severity of TR in patients with chronic AF. In this retrospective cohort study of adult patients referred for transthoracic echocardiography for evaluation of AF between 2004 and 2015, we identified 170 patients with chronic AF in the absence of structural or known coronary heart disease. Patients were classified into nonsevere (89 patients) versus severe TR (81 patients) groups based on a comprehensive assessment of color Doppler, spectral Doppler, and morphologic parameters of the tricuspid valve and right side of the heart. Patients with severe TR were significantly older (76 ± 10 vs 70 ± 11, p <0.001), with smaller body surface area (1.7 ± 0.3 m2 vs 1.9 ± 0.23 m2, p = 0.001) and with female predominance (percentage of men 30% vs 57%, p <0.001). Although comorbidities, use of cardiovascular medications, and left-sided cardiac parameters were statistically indistinguishable between these 2 groups, right-sided cardiac dimensions, tricuspid valve tethering height, and tricuspid valve tethering area were significantly larger in the severe TR group. A comprehensive multivariate logistic regression model (model 1) identified the age, gender, right ventricular systolic pressure, right atrial volume index, and right ventricular end-diastolic area as independent factors associated with TR severity. A simplified logistic regression model using only clinical factors (model 2) confirmed the age, gender, and right ventricular systolic pressure as clinically relevant factors in relation to TR.

Small stress response proteins in Escherichia coli: proteins missed by classical proteomic studies.

Proteins of 50 or fewer amino acids are poorly characterized in all organisms. The corresponding genes are challenging to reliably annotate, and it is difficult to purify and characterize the small protein products. Due to these technical limitations, little is known about the abundance of small proteins, not to mention their biological functions. To begin to characterize these small proteins in Escherichia coli, we assayed their accumulation under a variety of growth conditions and after exposure to stress. We found that many small proteins accumulate under specific growth conditions or are stress induced. For some genes, the observed changes in protein levels were consistent with known transcriptional regulation, such as ArcA activation of the operons encoding yccB and ybgT. However, we also identified novel regulation, such as Zur repression of ykgMO, cyclic AMP response protein (CRP) repression of azuC, and CRP activation of ykgR. The levels of 11 small proteins increase after heat shock, and induction of at least 1 of these, YobF, occurs at a posttranscriptional level. These results show that small proteins are an overlooked subset of stress response proteins in E. coli and provide information that will be valuable for determining the functions of these proteins.