Novel Betacoronavirus in Dromedaries of the Middle East, 2013

In 2013, a novel betacoronavirus was identified in fecal samples from dromedaries in Dubai, United Arab Emirates. Antibodies against the recombinant nucleocapsid protein of the virus, which we named dromedary camel coronavirus (DcCoV) UAE-HKU23, were detected in 52% of 59 dromedary serum samples tested. In an analysis of 3 complete DcCoV UAE-HKU23 genomes, we identified the virus as a betacoronavirus in lineage A1. The DcCoV UAE-HKU23 genome has G+C contents; a general preference for G/C in the third position of codons; a cleavage site for spike protein; and a membrane protein of similar length to that of other betacoronavirus A1 members, to which DcCoV UAE-HKU23 is phylogenetically closely related. Along with this coronavirus, viruses of at least 8 other families have been found to infect camels. Because camels have a close association with humans, continuous surveillance should be conducted to understand the potential for virus emergence in camels and for virus transmission to humans.     

Eosinophils stimulate fibroblast DNA synthesis

Fibrosis complicates a number of chronic inflammatory diseases and occurs in some conditions following chronic hypereosinophilic syndromes. We assessed whether eosinophils might be a source of fibrogenic factors. Extracts of human and guinea pig cell populations enriched for eosinophils contained substances that stimulated tritiated thymidine incorporation by human fibroblasts. Supernatants derived from resting eosinophils and extracts prepared from eosinophil granules also contained fibrogenic factors. Our findings demonstrate a new potential role for eosinophils and suggest a causal relationship between tissue eosinophilia and scar formation in certain parasitic conditions.     

Structural and functional remodeling of the left atrium: clinical and therapeutic implications for atrial fibrillation

Left atrial (LA) structural and functional remodeling reflects a spectrum of pathophysiological changes that have occurred in response to specific stressors. These changes include alterations at the levels of ionic channels, cellular energy balance, neurohormonal expression, inflammatory response, and physiologic adaptations. There is convincing evidence demonstrating an important pathophysiological association between LA remodeling and atrial fibrillation (AF). Measures that will prevent, attenuate, or halt these processes of LA remodeling may have a major public health impact with respect to the epidemic of AF. In this review, we describe the mechanisms involved in LA remodeling and highlight the existing and potential therapeutic options for its reversal, and implications for AF development.     

Left atrial volume predicts the risk of atrial fibrillation after cardiac surgery: a prospective study.

OBJECTIVES: This study sought to identify preoperative predictors of postoperative atrial fibrillation (POAF) among patients undergoing cardiac surgery. BACKGROUND: Postoperative atrial fibrillation is frequent after cardiac surgery and is associated with increased morbidity, mortality, prolonged hospital stay, and increased costs. Left atrial volume (LAV), a marker of chronically elevated left ventricular filling pressure, is a predictor of atrial fibrillation (AF) in the nonsurgical setting. METHODS: A total of 205 patients (mean age 62 +/- 16 years; 35% women) undergoing cardiac surgery were prospectively enrolled. Clinical risk factors were obtained by detailed medical record review and patient interview. Preoperative transthoracic echocardiograms were performed for assessment of LAV, left ventricular ejection fraction, and diastolic function. Follow-up was complete. Detection of POAF was based on documentation of AF episodes by continuous telemetry throughout hospitalization. RESULTS: Postoperative atrial fibrillation occurred in 84 patients (41.4%) at a median of 1.8 days after cardiac surgery. The LAV was significantly larger in patients in whom AF developed (49 +/- 14 ml/m2 vs. 39 +/- 16 ml/m2, p = 0.0001). Patients with LAV >32 ml/m2 had an almost five-fold increased risk of POAF, independently of age and clinical risk factors (adjusted hazard ratio 4.84, 95% confidence interval 1.93 to 12.17, p = 0.001). Age and LAV were the only independent predictors of POAF. The area under the receiver-operator characteristics curve to predict POAF was 0.729 for LAV and 0.768 for the combination of LAV and age (both p < 0.0001). CONCLUSIONS: The LAV is a strong and independent predictor of POAF. Risk stratification using LAV and age enables clinicians to identify high-risk patients before cardiac surgery.     

Relationship between complex fractionated electrograms (CFE) and dominant frequency (DF) sites and prospective assessment of adding DF-guided ablation to pulmonary vein isolation in persistent atrial fibrillation (AF)

Dominant Frequency Mapping and Ablation . Background: Sites of high DF are potential targets for AF ablation, but it is unknown if addition of DF ablation can improve procedural outcome. Objectives: We sought to (1) examine the relationship between DF sites and complex fractionated electrograms (CFE) and (2) prospectively assess the long‐term outcome of adding DF ablation to pulmonary vein antral isolation (PVAI) for persistent AF. Methods: First, 20 patients with persistent AF who underwent previous CFE‐guided ablation and who had AF terminate during ablation were studied retrospectively (group I). Bipolar, 8‐second electrograms were collected by a circular catheter (288 ± 86 points/map). The EnSite NavX system allows for automated display of both CFE and DF maps. Electrograms with cycle length <120 ms were considered CFE and were compared to DF sites > 8 Hz (direct inverse relationship). Sites of AF termination were related to CFE and DF sites. Based on these observations, 30 different patients (group II) with persistent AF prospectively underwent DF‐guided ablation plus PVAI. They were followed every 3 months for 1 year (visit, Holter, ECG). These patients were compared to case‐matched controls undergoing PVAI alone (group III). Results: In group I, there was a significant, inverse correlation between DF and CFE values at each point (r =–0.24, P < 0.001). DF surface area was less than CFE area (27 ± 5 cm² vs 34 ± 4 cm², P = 0.03). CFE sites overlapped 48 ± 27% with the DF surface area. Nonoverlapping CFE sites were contiguous to DF sites. AF termination occurred where DF and CFE overlapped, and at these sites, DF was always greater than the mean DF for the map. In group II, all DF sites above the mean value were prospectively ablated during AF. AF termination was noted in only 2/30 (7%) patients. After DF ablation, PVAI was performed and termination increased to 4/30 patients (14%). At 1 year, freedom from atrial arrhythmia > 30 seconds occurred in 57% of DF+PVAI compared to 60% in patients receiving PVAI alone (P = 0.18). Conclusions: DF and CFE regions overlap only about 50%. AF termination retrospectively occurred on overlapping CFE/DF sites where DF was above the mean. However, prospective ablation of DF sites plus PVAI resulted in low AF termination rates, and did not improve 1 year success over PVAI alone. (J Cardiovasc Electrophysiol, Vol. 22, pp. 1309‐1316, December 2011)     

Na+/H+ exchange in granulosa cells of the three largest preovulatory follicles of the domestic hen

Sodium-dependent intracellular pH (pHi) regulation was compared in granulosa cells from the three largest avian ovarian follicles by monitoring the pHi with biscarboxyethylcarboxyfluorescein, a dye whose fluorescence increases with alkalinity. Collagenase-dispersed granulosa cells obtained from the largest (F1), second largest (F2), and third largest (F3) preovulatory follicles about 2-3 hr prior to expected ovulation of F1 were used in the present study. The resting pHi measured in nominally bicarbonate free buffer with extra-cellular Na+ (Nao+ = 144 mM) and external pH (pHo) of 7.3 was about 6.8 in cells from F1, F2, and F3. There was no correlation between the stage of follicular development and the pHi whether the follicles were removed in the early or late preovulatory period. After acute cytoplasmic acidification by exposure of cells to nigericin in choline+ buffer, or by the abrupt removal of ammonium chloride, complete recovery of pHi occurred in 4-5 min. The rate and magnitude of the recovery were dependent upon the concentration of Nao+ and were abolished when Nao+ was replaced completely by choline+. Recovery in the presence of Nao+ was inhibited dose-dependently by amiloride (sodium-hydrogen exchange inhibitor). There was no difference between the rate and the extent of pHi recovery in acid-loaded cells obtained from F1, F2, and F3. Furthermore, by varying the concentration of Nao+ between 0 and 144 mM both young and matured granulosa cells extruded acid at the same rate. In addition, amiloride inhibited the Nao+ dependency of pHi recovery to a similar degree in F1, F2, and F3 cells. Our observations demonstrate in avian granulosa cells the existence of a Nao+-dependent, amiloride-sensitive pHi regulatory system that is equally effective in cells obtained from the three largest yolk-filled follicles.     

Echocardiographic assessment of left ventricular diastolic function and filling pressure in atrial fibrillation

Diastolic dysfunction has been linked to 2 epidemics: atrial fibrillation (AF) and heart failure. The presence and severity of diastolic dysfunction are associated with an increased risk for first AF and first heart failure in patients with sinus rhythm. Furthermore, the risk for heart failure is markedly increased once AF develops. The evaluation of diastolic function once AF has developed remains a clinical challenge. The conventional use of Doppler echocardiography for the assessment and grading of diastolic dysfunction relies heavily on evaluating the relation of ventricular and atrial flow characteristics. The mechanical impairment of the left atrium and the variable cycle lengths in AF render the evaluation of diastolic function difficult. A few Doppler echocardiographic methods have been proved clinically useful for the estimation of diastolic left ventricular filling pressures in AF, but these appear to be underutilized. Several innovative methods are emerging that promise to provide greater precision in diastolic function assessment, but their clinical utility in AF remains to be established. In conclusion, this review provides an up-to-date discussion of the evaluation of diastolic function assessment in AF and how it may be important in the clinical management of patients with AF.     

Non-invasive mechanical ventilation for cystic fibrosis patients--a potential bridge to transplantation

The case histories of six cystic fibrosis patients awaiting heart-lung transplantation are reviewed. They all deteriorated with severe hypoxia and hypercapnia before donor organs became available. Nasal intermittent positive pressure ventilation was used in preference to conventional ventilation with excellent results in four patients. There were no episodes of hypotension or toxaemia and the patients were in a stable condition at the time of surgery and made an excellent post-operative recovery. The patients who were transplanted and the patient who died, for whom suitable donor organs did not become available, probably had a more comfortable time than they would have done if treated with conventional ventilation. This method of ventilation appears to be a useful bridge to transplantation when a patient suddenly deteriorates. It gives them a chance of survival for a few more days or even weeks during which time an urgent search for donor organs can be made. This is also a very cost effective method of ventilation and does not encroach on conventional Intensive Care Unit (ICU) facilities.