An SI3-σ arch stabilizes cyanobacteria transcription initiation complex.

Multisubunit RNA polymerases (RNAPs) associate with initiation factors (σ in bacteria) to start transcription. The σ factors are responsible for recognizing and unwinding promoter DNA in all bacterial RNAPs. Here, we report two cryo-EM structures of cyanobacterial transcription initiation complexes at near-atomic resolutions. The structures show that cyanobacterial RNAP forms an "SI3-σ" arch interaction between domain 2 of σA (σ2) and sequence insertion 3 (SI3) in the mobile catalytic domain Trigger Loop (TL). The "SI3-σ" arch facilitates transcription initiation from promoters of different classes through sealing the main cleft and thereby stabilizing the RNAP-promoter DNA open complex. Disruption of the "SI3-σ" arch disturbs cyanobacteria growth and stress response. Our study reports the structure of cyanobacterial RNAP and a unique mechanism for its transcription initiation. Our data suggest functional plasticity of SI3 and provide the foundation for further research into cyanobacterial and chloroplast transcription.

Blood metabolomic fingerprint is distinct in healthy coronary and in stenosing or microvascular ischemic heart disease.

BACKGROUND: The endothelium is a key variable in the pathogenesis of atherosclerosis and its complications, particularly coronary artery disease (CAD). Current evidence suggests that the endothelial status can be regarded as an integrated index of individual atherogenic and anti-atherogenic properties, and that the interaction between circulating factors and the arterial wall might be critical for atherogenesis. In organism-level investigations, a functional view is provided by metabolomics, the study of the metabolic profile of small molecules. We sought to verify whether metabolomic analysis can reveal the presence of coronary microenvironment peculiarities associated with distinct manifestations of CAD. METHODS: Thirty-two coronary blood samples were analyzed using 1H-NMR-based metabolomics. Samples collected from patients with evidence of myocardial ischemia formed the case group, and were further divided into the stenotic-disease (SD) group (N = 13) and absence of stenosis (microvascular disease; "Micro") group (N = 8); specimens of patients presenting no evidence of ischemic heart disease (dilated cardiomyopathy, valvular diseases) constituted the control group (N = 11). RESULTS: Application of an orthogonal partial least squares discriminant analysis (OPLS-DA) model to the entire dataset clearly separated the samples into 3 groups, indicating 3 distinct metabolic fingerprints. Relative to control-group members, Micro patients showed a higher content of 2-hydroxybutirate, alanine, leucine, isoleucine, and N-acetyl groups and lower levels of creatine/phosphocreatine, creatinine, and glucose, whereas SD patients showed higher levels of 3-hydroxybutirate and acetate and a lower content of 2-hydroxybutirate. Moreover, relative to SD patients, Micro patients showed higher levels of 2-hydroxybutirate, alanine, leucine, and N-acetyl groups and lower levels of 3-hydroxybutirate and acetate. CONCLUSIONS: Specific coronary microenvironments are likely associated with distinct development and pathological expression of CAD.

Care quality monitoring of a ST-segment elevation myocardial infarction programme over a 5-year period.

AIMS: The aim of this study is to investigate the long-term impact of a prehospital ECG programme on treatment times for patients with ST-elevation myocardial infarction (STEMI) undergoing primary percutaneous coronary intervention (PCI). METHODS: From January 2008 to December 2012, 213 STEMI patients transported by the Emergency Medical System (EMS) underwent primary PCI in our Hospital. The protocol included ECG tele-transmission, early activation of the cath lab and direct routing of the patient for primary PCI. Fifty-four patients referred by EMS in 2007, when ECG tele-transmission was unavailable, were used as controls. First diagnostic ECG-to-balloon time, door-to-balloon time and total ischemic time were collected for all patients. RESULTS: First diagnostic ECG-to-balloon time decreased from 125.5 min in 2007 to 104 min in the first year after implementation of the STEMI programme (2008). Successively, it declined to 81 min by the end of the study period (2012) (P < 0.0001). Door-to-balloon time decreased notably from 92.5 min in 2007 to 40.5 min by the end of the study period (p < 0.0001). Total ischemic time fell from 200 min in 2007 to 170 min in 2008 and it further declined to 163.5 min in 2012 (p < 0.042). CONCLUSIONS: We report progressive improvements in times to treatment over a 5-year period in a STEMI program for patients referred by the EMS. The importance of data collection and monitoring is highlighted by our results.

Early noninvasive evaluation of coronary flow reserve after angioplasty in the left anterior descending coronary artery identifies patients at high risk of restenosis at follow-up.

BACKGROUND: Coronary restenosis is the most important clinical limitation after percutaneous coronary intervention (PCI), and coronary flow reserve (CFR) is reduced in the presence of significant coronary stenosis. This study evaluated whether detection of early reduction of Doppler echocardiographically derived CFR in the left anterior descending coronary artery can identify patients at high risk for developing restenosis after successful PCI. METHODS: Doppler echocardiographically derived CFR was studied in 124 consecutive patients at 1-month and 6-month follow-up after PCI in the left anterior descending coronary artery, together with coronary angiography. RESULTS: Restenosis was detected in 39 angiographic examinations (group A) and no coronary restenosis in the remaining 85 (group B) at 6 months. At 1 month, CFR was reduced in group A compared with group B (P < .0001), and a significant reduction of CFR in group A (P < .0001) but not in group B (P = .89) was detected at 6 months. CFR ≤ 2.5 at 1 month was 67% sensitive and 87% specific for predicting significant restenosis, with positive and negative predictive values of 67% and 87%, respectively. CONCLUSIONS: CFR ≤ 2.5 detected 1 month after PCI in the left anterior descending coronary artery has the potential to identify patients at higher risk for developing coronary restenosis and indicates the need for close clinical follow-up.

Detection of coronary restenosis after coronary angioplasty by contrast-enhanced transthoracic echocardiographic Doppler assessment of coronary flow velocity reserve.

OBJECTIVES: This study sought to evaluate the diagnostic potential of contrast-enhanced transthoracic echocardiography (CE-TTE) during adenosine infusion, a noninvasive method for evaluating coronary flow reserve (CFR), in detecting restenosis after successful percutaneous transluminal coronary angioplasty (PTCA). BACKGROUND: Restenosis is the most important limitation of PTCA, and CFR can be impaired in patients with angiographically documented significant coronary stenosis. METHODS: We performed 6 +/- 2 months of follow-up of 53 patients after successful elective PTCA in the left anterior descending coronary artery (LAD). Coronary angiography was performed at the end of the planned follow-up period or even before, if clinically indicated. Thus, of the 53 patients, a total of 63 angiographic studies were performed; CE-TTE assessment of CFR was achieved before each of the 63 angiographic studies. RESULTS: Coronary angiography revealed the presence of restenosis (defined as >50% stenosis at a previous PTCA site) in 32 angiographic examinations (group A) and no coronary restenosis in the remaining 31 examinations (group B). Coronary flow reserve was significantly reduced in group A compared with group B (1.65 +/- 0.5 vs. 3.17 +/- 0.8, p < or = 0.001). A noninvasive CFR value < or = 2 was 93% specific and 78% sensitive for detecting significant restenosis, with positive and negative diagnostic accuracies of 92% and 80%, respectively. CONCLUSIONS: Noninvasive CFR assessment by CE-TTE is an accurate method of monitoring significant restenosis in the LAD when following up patients submitted to elective PTCA.