Silage review: Using molecular approaches to define the microbial ecology of silage.

Ensiling of forages was recognized as a microbial-driven process as early as the late 1800s, when it was associated with the production of "sweet" or "sour" silage. Classical microbiological plating techniques defined the epiphytic microbial populations associated with fresh forage, the pivotal role of lactic acid-producing bacteria in the ensiling process, and the contribution of clostridia, bacilli, yeast, and molds to the spoilage of silage. Many of these classical studies focused on the enumeration and characterization of a limited number of microbial species that could be readily isolated on selective media. Evidence suggested that many of the members of these microbial populations were viable but unculturable, resulting in classical studies underestimating the true microbial diversity associated with ensiling. Polymerase chain reaction-based techniques, including length heterogeneity PCR, terminal RFLP, denaturing gradient gel electrophoresis, and automated ribosomal intergenic spacer analysis, were the first molecular methods used to study silage microbial communities. Further advancements in whole comparative genomic, metagenomic, and metatranscriptomic sequencing have or are in the process of superseding these methods, enabling microbial communities during ensiling to be defined with a degree of detail that is impossible using classical microbiology. These methods have identified new microbial species in silage, as well as characterized shifts in microbial communities with forage type and composition, ensiling method, and in response to aerobic exposure. Strain- and species-specific primers have been used to track the persistence and contribution of silage inoculants to the ensiling process and the role of specific species of yeast and fungi in silage spoilage. Sampling and the methods used to isolate genetic materials for further molecular analysis can have a profound effect on results. Primer selection for PCR amplification and the presence of inhibitors can also lead to biases in the interpretation of sequence data. Bioinformatic analyses are reliant on the integrity and presence of sequence data within established databases and can be subject to low taxonomic resolution. Despite these limitations, advancements in molecular biology are poised to revolutionize our current understanding of the microbial ecology of silage.

Human rhinovirus-induced ISG15 selectively modulates epithelial antiviral immunity.

Human rhinovirus (HRV) infections trigger exacerbations of lower airway diseases. HRV infects human airway epithelial cells and induces proinflammatory and antiviral molecules that regulate the response to HRV infection. Interferon (IFN)-stimulated gene of 15 kDa (ISG15) has been shown to regulate other viruses. We now show that HRV-16 infection induces both intracellular epithelial ISG15 expression and ISG15 secretion in vitro. Moreover, ISG15 protein levels increased in nasal secretions of subjects with symptomatic HRV infections. HRV-16-induced ISG15 expression is transcriptionally regulated via an IFN regulatory factor pathway. ISG15 does not directly alter HRV replication but does modulate immune signaling via the viral sensor protein RIG-I to impact production of CXCL10, which has been linked to innate immunity to viruses. Extracellular ISG15 also alters CXCL10 production. We conclude that ISG15 has a complex role in host defense against HRV infection, and that additional studies are needed to clarify the role of this molecule.

Optimized temporary bi-ventricular pacing improves haemodynamic function after on-pump cardiac surgery in patients with severe left ventricular systolic dysfunction: a two-centre randomized control trial.

OBJECTIVES: Optimized temporary bi-ventricular (BiV) pacing may benefit heart failure patients after on-pump cardiac surgery compared with conventional dual-chamber right ventricular (RV) pacing. An improvement in haemodynamic function with BiV pacing may reduce the duration of 'Level 3' intensive care. METHODS: Thirty-eight patients in sinus rhythm, ejection fraction ≤35%, undergoing on-pump surgical revascularization, valve surgery or both were enrolled in this study. Before closing the sternum, temporary epicardial pacing wires were attached to the right atrium, RV outflow tract and basal posterolateral wall of the left ventricle. Patients were randomly assigned to postoperative BiV pacing with the optimization of the atrio- (AV) and inter-ventricular (VV) pacing intervals (Group 1) or conventional dual-chamber right AV pacing (Group 2). The primary end-point was the duration of 'Level 3' intensive care. Secondary end-points included cardiac output which was measured by thermodiluation at admission to the intensive care unit and at 6 and 18 h later, in five different pacing modes. RESULTS: The duration of 'Level 3' care was similar between groups (40 ± 35 vs 54 ± 63 h; Group 1 vs 2; P = 0.43). Cardiac output was similar in all pacing modes at baseline. At 18 h, cardiac output with BiV pacing (5.8 l/min) was 7% higher than atrial inhibited (5.4 l/min) and 9% higher than dual-chamber RV pacing (5.3 l/min; P = 0.02 and 0.001, respectively). Optimization of the VV interval produced a further 4% increase in cardiac output compared with baseline settings (P = 0.005). CONCLUSIONS: Postoperative haemodynamic function may be enhanced by temporary BiV pacing of high-risk patients after on-pump cardiac surgery.

Temporary epicardial cardiac resynchronisation versus conventional right ventricular pacing after cardiac surgery: study protocol for a randomised control trial.

BACKGROUND: Heart failure patients with stable angina, acute coronary syndromes and valvular heart disease may benefit from revascularisation and/or valve surgery. However, the mortality rate is increased- 5-30%. Biventricular pacing using temporary epicardial wires after surgery is a potential mechanism to improve cardiac function and clinical endpoints. METHOD/DESIGN: A multi-centred, prospective, randomised, single-blinded, intervention-control trial of temporary biventricular pacing versus standard pacing. Patients with ischaemic cardiomyopathy, valvular heart disease or both, an ejection fraction ≤ 35% and a conventional indication for cardiac surgery will be recruited from 2 cardiac centres. Baseline investigations will include: an electrocardiogram to confirm sinus rhythm and measure QRS duration; echocardiogram to evaluate left ventricular function and markers of mechanical dyssynchrony; dobutamine echocardiogram for viability and blood tests for renal function and biomarkers of myocardial injury- troponin T and brain naturetic peptide. Blood tests will be repeated at 18, 48 and 72 hours. The principal exclusions will be subjects with permanent atrial arrhythmias, permanent pacemakers, infective endocarditis or end-stage renal disease.After surgery, temporary pacing wires will be attached to the postero-lateral wall of the left ventricle, the right atrium and right ventricle and connected to a triple chamber temporary pacemaker. Subjects will be randomised to receive either temporary biventricular pacing or standard pacing (atrial inhibited pacing or atrial-synchronous right ventricular pacing) for 48 hours.The primary endpoint will be the duration of level 3 care. In brief, this is the requirement for invasive ventilation, multi-organ support or more than one inotrope/vasoconstrictor. Haemodynamic studies will be performed at baseline, 6, 18 and 24 hours after surgery using a pulmonary arterial catheter. Measurements will be taken in the following pacing modes: atrial inhibited; right ventricular only; atrial synchronous-right ventricular; atrial synchronous-left ventricular and biventricular pacing. Optimisation of the atrioventricular and interventricular delay will be performed in the biventricular pacing group at 18 hours. The effect of biventricular pacing on myocardial injury, post operative arrhythmias and renal function will also be quantified. TRIAL REGISTRATION: ClinicalTrials.gov: NCT01027299.

The role of echocardiography in guiding management in dilated cardiomyopathy.

Dilated cardiomyopathy (DCM) is a common and malignant condition, which carries a poor long-term prognosis. Underlying disease aetiologies are varied, and often carry specific implications for treatment and prognosis. The role of echocardiography is essential in not only establishing the diagnosis, but also in defining the aetiology, and understanding the pathophysiology. This article therefore explores the pivotal role of echocardiography in the evaluation and management of patients with DCM.

Left ventricular non-compaction: clinical features and cardiovascular magnetic resonance imaging.

BACKGROUND: It is apparent that despite lack of family history, patients with the morphological characteristics of left ventricular non-compaction develop arrhythmias, thrombo-embolism and left ventricular dysfunction. METHODS: Forty two patients, aged 48.7 +/- 2.3 yrs (mean +/- SEM) underwent cardiovascular magnetic resonance (CMR) for the quantification of left ventricular volumes and extent of non-compacted (NC) myocardium. The latter was quantified using planimetry on the two-chamber long axis LV view (NC area). The patients included those referred specifically for CMR to investigate suspected cardiomyopathy, and as such is represents a selected group of patients. RESULTS: At presentation, 50% had dyspnoea, 19% chest pain, 14% palpitations and 5% stroke. Pulmonary embolism had occurred in 7% and brachial artery embolism in 2%. The ECG was abnormal in 81% and atrial fibrillation occurred in 29%. Transthoracic echocardiograms showed features of NC in only 10%. On CMR, patients who presented with dyspnoea had greater left ventricular volumes (both p < 0.0001) and a lower left ventricular ejection fraction (LVEF) (p < 0.0001) than age-matched, healthy controls. In patients without dyspnoea (n = 21), NC area correlated positively with end-diastolic volume (r = 0.52, p = 0.0184) and end-systolic volume (r = 0.56, p = 0.0095), and negatively with EF (r = -0.72, p = 0.0001). CONCLUSION: Left ventricular non-compaction is associated with dysrrhythmias, thromboembolic events, chest pain and LV dysfunction. The inverse correlation between NC area and EF suggests that NC contributes to left ventricular dysfunction.

A critical comparison of echocardiographic measurements used for optimizing cardiac resynchronization therapy: stroke distance is best.

AIMS: Dyssynchrony assessment in cardiac resynchronization therapy (CRT) is controversial, and there are no standard protocols for optimizing treatment. We studied the feasibility and reproducibility of several echocardiographic measures to optimize CRT pacemaker settings. We also assessed the utility of 'stroke distance' [left ventricular outflow tract velocity-time integral (LVOT VTI)] in performing this function. METHODS AND RESULTS: Thirty patients underwent the following functional assessments; 6 min walk test distance, peak VO(2) consumption on cardiopulmonary exercise testing (VO(2) peak), quality-of-life scoring, and echocardiography; before and at 3 and 6 months after implantation of the CRT device. At 3 months, patients received LVOT VTI-guided optimization of interventricular (VV) and atrioventricular (AV) delays. The feasibility and reproducibility of each optimization measurement was statistically analysed, and the functional benefits of optimization examined. Left ventricular outflow tract VTI, interventricular mechanical delay (IVMD), and tissue Doppler lateral-septal delay showed good feasibility (>90%), whereas LVOT VTI, IVMD, and the 12-segment tissue Doppler dyssynchrony index showed good reproducibility (coefficient of variation <20%). The most feasible and reproducible measure was LVOT VTI. Our optimization protocol necessitated alteration of AV and/or VV delays in 60% of patients at 3 months and was associated with a 50% improvement in functional responder status between 3 and 6 months. CONCLUSION: Left ventricular outflow tract VTI provides us with a single, direct measure of global LV function which is robust, and easily applicable in routine clinical practice, and which is effective at improving response to CRT.

Acquired left ventricular outflow tract obstruction and cardiogenic shock treated with beta-blockers.

Beta-blockers are normally contraindicated in the treatment of cardiogenic shock. A 70-year-old lady presents with an acute coronary syndrome complicated by critical cardiogenic shock. Coronary angiography shows an ulcerated nonobstructing plaque in the left anterior descending artery. She fails to improve with standard treatment with inotrope and intraaortic balloon pump. Echocardiography revealed acquired left ventricular outflow tract (LVOT) obstruction and secondary mitral regurgitation. Treatment with intravenous beta-blockers produced both clinical and hemodynamic improvement as well as resolution of LVOT obstruction. Echocardiography is essential in defining the mechanism of cardiogenic shock in patients with acute coronary syndrome. Inotropic support exacerbates cardiogenic shock due to acquired LVOT obstruction that is best treated with beta-blockers.

Late gadolinium enhancement-cardiovascular magnetic resonance as a predictor of response to cardiac resynchronization therapy in patients with ischaemic cardiomyopathy.

AIM: To determine whether myocardial scarring, quantified using late gadolinium enhancement-cardiovascular magnetic resonance (LGE-CMR), predicts response to cardiac resynchronization therapy (CRT). METHODS AND RESULTS: A total of 45 patients with ischaemic cardiomyopathy [age 67.1 +/- 10.4 years (mean +/- SD)] underwent assessment of 6 min walking distance (6MWD) and quality of life (QoL) before and after CRT. Scar size (percentage of left ventricular mass), location, and transmurality were assessed prior to CRT using LGE-CMR. Responders (survived for 1 year with no heart failure hospitalizations, and improvement by >or=1 NYHA classes or >or=25% 6MWD) had a higher left ventricular ejection fraction (P = 0.048), smaller scars (<33%) (P = 0.009), and fewer scars with >or=51% transmurality (P = 0.002). Scar size correlated negatively with change in 6MWD (r = -0.54, P < 0.001) and positively with changes in QoL scores (r = 0.35, P = 0.028). Responder rates in patients with <33% scar were higher than in those with >or=33% scar (82 vs. 35%, P < 0.01). Responder rates in patients with scar transmurality <51% were higher than in those with >or=51% (89 vs. 46%, P < 0.01). Among the patients with posterolateral scars, a transmurality value of >or=51% was associated with a particularly poor response rate (23%), compared with scars with <51% transmurality (88%, P < 0.001). In multivariate analyses, both scar size (P = 0.022) and transmurality (P = 0.004) emerged as predictors of response. In patients with posterolateral scars, pacing outside the scar was associated with a better responder rate than pacing over the scar (86 vs. 33%, P = 0.004). CONCLUSIONS: In patients with ischaemic cardiomyopathy, a scar size >or=33%, a transmurality >or=51%, and pacing over a posterolateral scar are associated with a suboptimal response to CRT.

Mapping the Sinorhizobium meliloti 1021 solute-binding protein-dependent transportome.

The number of solute-binding protein-dependent transporters in rhizobia is dramatically increased compared with the majority of other bacteria so far sequenced. This increase may be due to the high affinity of solute-binding proteins for solutes, permitting the acquisition of a broad range of growth-limiting nutrients from soil and the rhizosphere. The transcriptional induction of these transporters was studied by creating a suite of plasmid and integrated fusions to nearly all ATP-binding cassette (ABC) and tripartite ATP-independent periplasmic (TRAP) transporters of Sinorhizobium meliloti. In total, specific inducers were identified for 76 transport systems, amounting to approximately 47% of the ABC uptake systems and 53% of the TRAP transporters in S. meliloti. Of these transport systems, 64 are previously uncharacterized in Rhizobia and 24 were induced by solutes not known to be transported by ABC- or TRAP-uptake systems in any organism. This study provides a global expression map of one of the largest transporter families (transportome) and an invaluable tool to both understand their solute specificity and the relationships between members of large paralogous families.

Pacing-induced increase in QT dispersion predicts sudden cardiac death following cardiac resynchronization therapy.

OBJECTIVES: This study was designed to determine whether cardiac resynchronization therapy (CRT) by means of biventricular pacing (BiVP) alters the QT interval (QT(c)) and QT dispersion (QTD), and whether such changes relate to the risk of developing major arrhythmic events (MAE). BACKGROUND: Prolonged QT(c) is associated with MAE. Left ventricular pacing and BiVP alter QT(c). METHODS: A total of 75 patients with drug-resistant heart failure (New York Heart Association functional class III/IV) and QRS duration > or =120 ms underwent CRT. The QT(c) and QTD were measured before and 48 days after BiVP. RESULTS: Over 807 days (range 93 to 1,543 days), 11 patients had a MAE. Compared to baseline, at 48 days after CRT, QTD increased in 47% of patients and QT(c) decreased in 53%. The QT(c) at follow-up was higher in MAE patients compared with no-MAE patients (35.9 +/- 14.2 ms vs. 0.52 +/- 6.0 ms; p = 0.0323). Similar differential responses for QTD were observed (46.4 +/- 13.5 ms in MAE vs. -5.1 +/- 4.1 ms in no MAE, p < 0.0001). The MAE occurred in 29% of patients exhibiting an increase in QTD and in 3% of those exhibiting a decrease (p = 0.0017). In multiple regression analyses, change in QTD from baseline (DeltaQTD) strongly predicted MAE, independent of DeltaQT(c), QRS duration, and left ventricular ejection fraction and end-diastolic volume (p < 0.001). Differences in survival curves were observed when patients were dichotomized according to whether QTD increased or decreased in relation to baseline values (p < 0.0001). CONCLUSIONS: The MAE in patients with BiVP are related to pacing-induced increases in QTD. Measures of ventricular repolarization at the time of pacemaker implantation may guide selection of patients for combined CRT and defibrillator therapy.

Late intervention after anterior myocardial infarction: effects on left ventricular size, function, quality of life, and exercise tolerance: results of the Open Artery Trial (TOAT Study).

OBJECTIVE: We sought to conduct a randomized trial comparing late revascularization with conservative therapy in symptom-free patients after acute myocardial infarction (AMI). BACKGROUND: In the absence of ischemia, the benefits of reperfusion late after AMI remain controversial. However, the possibility exists that an open infarct related artery benefits healing post AMI. METHODS: Of 223 patients enrolled with Q-wave anterior AMI, 66 with isolated persistent occlusion of the left anterior descending coronary artery (LAD) were randomized to the following treatments: 1) medical therapy (closed artery group; n = 34) or 2) late intervention and stent to the LAD + medical therapy (open artery group; n = 32). The study was powered to compare left ventricular (LV) end-systolic volume between the two groups 12 months post AMI. RESULTS: Late intervention 26 +/- 18 days post AMI resulted in significantly greater LV end-systolic and end-diastolic volumes at 12 months than medical therapy alone (106.6 +/- 37.5 ml vs. 79.7 +/- 34.4 ml, p < 0.01 and 162.0 +/- 51.4 ml vs. 130.1 +/- 46.1 ml, p < 0.01, respectively). Exercise duration and peak workload significantly increased in both groups from 6 weeks to 12 months post AMI, although absolute values were greater in the open artery group. Quality of life scores tended to deteriorate during this time interval in the closed artery patients but remained unchanged in the open artery patients. Coronary angiography at 1 year documented a low incidence of intergroup cross-over (spontaneous recanalization in 19% and closure in 11%). CONCLUSIONS: In the present study, recanalization of occluded infarct-related arteries in symptom-free patients approximately 1 month post AMI had an adverse effect on remodeling but tended to increase exercise tolerance and improve quality of life.