CHD6, a cellular repressor of influenza virus replication, is degraded in human alveolar epithelial cells and mice lungs during infection.

The influenza virus polymerase associates to an important number of transcription-related proteins, including the largest subunit of the RNA polymerase II complex (RNAP II). Despite this association, degradation of the RNAP II takes place in the infected cells once viral transcription is completed. We have previously shown that the chromatin remodeler CHD6 protein interacts with the influenza virus polymerase complex, represses viral replication, and relocalizes to inactive chromatin during influenza virus infection. In this paper, we report that CHD6 acts as a negative modulator of the influenza virus polymerase activity and is also subjected to degradation through a process that includes the following characteristics: (i) the cellular proteasome is not implicated, (ii) the sole expression of the three viral polymerase subunits from its cloned cDNAs is sufficient to induce proteolysis, and (iii) degradation is also observed in vivo in lungs of infected mice and correlates with the increase of viral titers in the lungs. Collectively, the data indicate that CHD6 degradation is a general effect exerted by influenza A viruses and suggest that this viral repressor may play an important inhibitory role since degradation and accumulation into inactive chromatin occur during the infection.

CHD6 chromatin remodeler is a negative modulator of influenza virus replication that relocates to inactive chromatin upon infection.

The influenza virus establishes close functional and structural connections with the nucleus of the infected cell. Thus, viral ribonucleoproteins (RNPs) are closely bound to chromatin components and the main constituent of viral RNPs, the nucleoprotein (NP) protein, interacts with histone tails. Using a yeast two-hybrid screening, we previously found that the PA influenza virus polymerase subunit interacts with the CHD6 protein, a member of the CHD family of chromatin remodelers. Here we show that CHD6 also interacts with the viral polymerase complex and colocalizes with viral RNPs in the infected cells. To study the relationships between RNPs, chromatin and CHD6, we have analysed whether NP and CHD6 binds to peptides representing trimethylated lysines of histone 3 tails that mark transcriptionally active or inactive chromatin. Upon infection, NP binds to marks of repressed chromatin and, interestingly an important recruitment of CHD6 to these heterochromatin marks occurs in this situation. Silencing experiments indicate that CHD6 acts as a negative modulator of influenza virus replication. Hence, the CHD6 association with inactive chromatin could be part of a process where the influenza virus triggers modifications of chromatin-associated proteins that could contribute to the pathogenic events used by the virus to induce host cell shut-off.

Ventricular mechanical asynchrony in patients with different degrees of systolic dysfunction: results from AVE Registry by the Italian Society of Cardiovascular Echography (SIEC).

OBJECTIVE: The aim of the study was to compare the prevalence of interventricular and intraventricular asynchrony in patients with different degrees of left ventricular (LV) dysfunction. METHODS: We enrolled 182 patients (male 79%, mean age 64 +/- 11 years) with LV ejection fraction (EF) < 50% and identified two groups: Group A (n = 79) with mild-to-moderate LV dysfunction (EF between 36% and 49%) and Group B (n = 103) with severe dysfunction (EF 102 msec) did not differ between groups either (29.9% vs. 35.9%; P = 0.39). CONCLUSIONS: The prevalence of intraventricular asynchrony is independent of the LV systolic dysfunction severity. This could indicate the potential role of cardiac resynchronization therapy in patients with mild-moderate systolic dysfunction.

Right atrial mass following transcatheter radiofrequency ablation for recurrent atrial fibrillation: thrombus, endocarditis or mixoma?

We report a case of an asymptomatic patient in whom a right atrial mass was fortuitously documented by echocardiography few months after a transcatheter radiofrequency catheter ablation for recurrent AF. No masses were seen in the cardiac chambers before the ablative procedure, raising important diagnostic and decision-making issues. The patient was referred to the surgeon and a diagnosis of right atrial myxoma was made.

Influenza virus polymerase: Functions on host range, inhibition of cellular response to infection and pathogenicity.

The viral polymerase is an essential complex for the influenza virus life cycle as it performs the viral RNA transcription and replication processes. To that end, the polymerase carries out a wide array of functions and associates to a large number of cellular proteins. Due to its importance, recent studies have found numerous mutations in all three polymerase protein subunits contributing to virus host range and pathogenicity. In this review, we will point out viral polymerase polymorphisms that have been associated with virus adaptation to mammalian hosts, increased viral polymerase activity and virulence. Furthermore, we will summarize the current knowledge regarding the new set of proteins expressed from the viral polymerase genes and their contribution to infection. In addition, the mechanisms used by the virus to counteract the cellular immune response in which the viral polymerase complex or its subunits are involved will be highlighted. Finally, the degradative process induced by the viral polymerase on the cellular transcription machinery and its repercussions on virus pathogenicity will be of particular interest.

Recoordination of opposing walls drives the response to cardiac resynchronization therapy: a longitudinal study using a strain discoordination index.

BACKGROUND AND AIMS: Intraventricular dyssynchrony has traditionally been studied by means of contraction delays between different myocardial segments. Recently, the discoordination of opposing wall contraction throughout the cardiac cycle has been proposed as a more faithful predictor of response. Aim of the current study was to evaluate which parameters - mechanical dyssynchrony or discoordination - normalize with left ventricular response to cardiac resynchronization therapy (CRT). METHODS: Cardiac mechanics were analysed before and after 6 months of CRT in 53 patients with left bundle branch block and advanced heart failure. Discoordination was quantified by means of the transverse strain discoordination index (TSDI) at basal and mid-ventricular segments; this index takes into account the percentage of time in the cardiac cycle in which cardiac deformation (transverse strain) of the two opposing walls occurs in noncoordinated directions. Dyssynchrony indices included septal to lateral peak-to-peak transverse strain delay and the standard deviation of time to peak tissue velocity in 12 mid-basal segments (Yu index). RESULTS: Around 63% of patients met the response criteria. Several baseline indices were predictive of reverse remodelling; TSDI at the mid-ventricular level demonstrated the best accuracy. Time from Q to peak velocity and strain tended to increase in all explored myocardial segments; despite a trend towards a decrease in septal-to-lateral strain delay, the latter decreased equally in responders and in nonresponding patients. Yu index decreased in responders more than in nonresponders, with borderline significance. Basal and medium TSDI remained unchanged in nonresponders and consistently normalized in patients who responded to CRT. The changes in TSDI were significantly correlated with improvements in left ventricular end-systolic volume and ejection fraction; the strongest correlation was observed for changes in TSDI measured at the mid-ventricular level. CONCLUSION: Left ventricular reverse remodelling after CRT is accompanied by the recoordination of opposite-wall contraction, as testified by changes in mid-ventricular TSDI, which also reveals as a very good predictor of response. On the contrary, changes of segmental peak-to-peak delays (dyssynchrony indices) fail to capture the complex nature of left ventricular response to CRT.

Influence of manual preflaring and torque on the failure rate of ProTaper rotary instruments.

We evaluated the influence of manual preflaring and torque on the failure rate of rotary nickel-titanium ProTaper instruments Shaping 1 (S1), Shaping 2 (S2), Finishing 1 (F1), and Finishing 2 (F2). These factors were evaluated using an in vitro method by calculating the mean number of Endo-Training-Blocks shaped before file breakage under different conditions. Group A (S1 on simulators with no preflaring) shaped 10 blocks before failure, group B (S1 on manually preflared simulators) shaped 59 blocks (p<0.01 versus group A), group C (S2 with low torque) shaped 28 blocks, group D (S2 with high torque) shaped 48 blocks (p<0.01 versus group C), group E (F1 with low torque) shaped eight blocks, group F (F1 with high torque) shaped 23 blocks (p<0.01 versus group E), group G (F2 with low torque) shaped four blocks, and group H (F2 with high torque) shaped 11 blocks (p<0.01 versus group G). Manual preflaring creates a glide path for the instrument tip and is a major determinant in reducing the failure rate of these rotary nickel-titanium files. All instruments worked better at high torque.

[Mitral stenosis: echocardiographic evaluation]. / Stenosi mitralica: valutazione ecocardiografica.

The diagnostic tools available for the evaluation of mitral stenosis are two-dimensional and Doppler echocardiography, which are able to identify morphologic and flow changes. Two-dimensional echocardiography can be used to assess the morphological appearance of the mitral valve apparatus, including its mobility and thickness and the presence of calcified leaflets and subvalvular fusion. Wilkins'score permits evaluation of each variable which, on the basis of its severity, is scored according to a point system ranging from 1 to 4. In patients with severe mitral stenosis, a low total score (< 8) and elastic symmetric commissures suggest valvuloplasty. A total score > 10 and the presence of more than mild mitral regurgitation or of calcification of both commissures suggest valvular replacement. The left atrial and ventricular chamber sizes and other associated valvular diseases can also be assessed at two-dimensional or Doppler echocardiography. The severity of obstruction can be assessed using two-dimensional and Doppler echocardiographic area (pressure half-time, proximal isovelocity surface area, continuity equation) and with the mean transmitral gradient measured using a continuous wave Doppler signal across the mitral valve. Valvuloplasty can also be performed in patients with a high score when surgery is contraindicated. During follow-up it is necessary to evaluate the area, the mean gradient, the right ventricular systolic pressure and the presence of a residual atrial septal defect and mitral regurgitation. Restenosis is diagnosed when the valve area decreases to 50% of that achieved during valvuloplasty or surgery.

Effects of volume loading on strain rate and tissue Doppler velocity imaging in patients with idiopathic dilated cardiomyopathy.

BACKGROUND: Strain rate is a promising echocardiographic technique which adds further information to that obtained with two-dimensional echocardiography and tissue Doppler imaging (TDI). The present study aimed to evaluate the effects of acute isotonic volume expansion on left ventricular function in patients with idiopathic dilated cardiomyopathy (DCM) utilizing TDI and strain rate measurements. METHODS: Ten patients with DCM and a left ventricular ejection fraction (LVEF)

Myocardial systolic activation delay in patients with left bundle branch block and either normal or impaired left ventricular function.

AIM OF THE STUDY: to evaluate determinants of myocardial activation delay of both left (LV) and right (RV) ventricle in patients with left bundle branch block (LBBB) and either normal or impaired LV ejection fraction (EF). METHODS: From an initial cohort of patients with LBBB, 42 patients with dilated cardiomyopathy (group A) and 33 with normal global LV systolic function (group B), all comparable in age and sex, underwent standard Doppler echo, pulsed Doppler myocardial imaging (DMI), and coronary angiography. Using DMI, the following regional parameters were evaluated in five different basal myocardial segments (LV anterior, inferior, septal, lateral walls-RV lateral wall): systolic (Sm), early- and late-diastolic (Em and Am) peak velocities. As index of myocardial systolic activation was calculated: precontraction time (PCTm) (from the beginning of Q-wave of ECG to the onset of Sm). Intraventricular systolic dyssynchrony was analyzed by difference of PCTm in different LV myocardial segments. Interventricular activation delay was calculated by the difference of PCTm between the most delayed LV segment and RV lateral wall. RESULTS: Patients of group A showed increased heart rate (HR), QRS duration and LV end-diastolic diameter, and reduced LV EF. By DMI, patients of group A showed reduced myocardial peak velocities and a significant intraventricular delay in activation of LV lateral wall, with increased regional PCTm (P < 0.001). In addition, patients with dilated cardiomyopathy showed a more pronounced interventricular dyssynchrony, even after adjustment for HR and QRS duration. By receiver operating characteristic (ROC) curve analysis, a cut-off value of 55 msec of interventricular delay showed 86% sensitivity and 92% specificity in identifying patients with impaired EF. In the overall population, by use of stepwise forward multivariate linear regression analyses, LV end-diastolic diameter (beta coefficient = 0.52; P < 0.001) and LV EF (beta coefficient =-0.58; P < 0.0001) were the only independent determinants of interventricular activation delay. CONCLUSIONS: Pulsed DMI is an effective noninvasive technique for assessing the severity of regional delay in activation of LV walls in patients with LBBB. The impairment of interventricular systolic sychronicity is strongly related to LV dilatation and to the degree of global systolic dysfunction. Therefore, patients with dilated cardiomyopathy suitable for cardiac resynchronization therapy may be better selected.

Assessment of accessory atrioventricular pathways by Doppler myocardial imaging.

PURPOSE: The use of electrophysiologic studies (EPS) for the localization of accessory atrioventricular connections in Wolff-Parkinson-White syndrome (WPW) requires accurate evaluation of the site of bypass tract insertion. Doppler myocardial imaging (DMI) is a new ultrasound technique that allows the detection of abnormal and early regional myocardial depolarization. The purpose of this study was to identify an abnormal pathway site in WPW patients. METHODS: Twenty-one patients with ventricular preexcitation were studied by DMI. Two-dimensional color DMI, velocity maps, acceleration maps, and pulsed-wave applications were used. A subsequent diagnostic EPS was performed. The results of EPS were taken as the gold standard diagnostic procedure. Radiofrequency catheter ablation therapy was then performed on all patients. RESULTS: The anomalous pathway was detected by DMI in 16 (76%) of 21 patients (9 [90%] of 10 with left pathways and 7 [64%] of 11 with right pathways), with respect to results of the EPS. Pathway detection was better with pulsed-wave DMI (76%) with its higher temporal resolution as compared with M-mode velocity map (57%) and acceleration map (47%). In most of the patients with successful radiofrequency ablation, an immediate resolution of the abnormal ventricular depolarization occurred and was detectable by DMI. CONCLUSIONS: Our findings demonstrate the feasibility of DMI to assess the early ventricular contraction associated with atrioventricular accessory pathways. Therefore, DMI appears to be a clinically useful adjunct to noninvasive evaluation of abnormal myocardial depolarization in WPW and to evaluate the results after radiofrequency ablation, even though its accuracy is considerably better for left-sided accessory pathways than for right-sided ones.

Reparación de hernias incisionales grandes con malla supraaponeurótica / Repair of big incisional hernias with supraaponeurotic mesh

Se presentan 17 enfermos intervenidos en el Hospital Universitario ôComandante Manuel Fajardoö durante 1996 al 2000, con hernias incisionales grandes reproducidas en más de una ocasión, con reparación mediante mallas de polipropileno o poliéster en posición prefascial o supraaponeurótica. En nuestra serie todos los enfermos habían sufrido al menos 2 intervenciones anteriores, 5 casos habían sido operados 4 veces y 1 en 7 ocasiones. En todos los casos se realizó una cuidadosa preparación preoperatoria que incluyó la preparación local de la piel y el restablecimiento de la capacidad toracoabdominal mediante neumoperitoneos, lo que hizo posible el afrontamiento fascia a fascia sin tensión. Los anillos herniarios midieron más de 10 cm, con promedio de 16. En todos los casos se utilizó la cefasolina como antibiótico profiláctico y no se produjo sepsis de la herida. No ocurrió recidiva herniaria, con un seguimiento promedio de 39,6 meses. No existieron hasta el momento manifestaciones de rechazo atribuibles al material protésico. No se reportaron complicaciones inmediatas como seroma o hematoma de la herida quirúrgica, al haberse colocado en todos los casos drenaje de la zona quirúrgica(AU)

17 patients that underwent surgery at Comandante Manuel Fajardo Teaching Hospital, from 1996 to 2000, with big incisional hernias reproduced in more than one ocassion, and with repair by polypropylene or polyester meshes in prefascial or supraaponeurotic position, were presented. In our series, all the patients had undergone at least 2 previous operations. 5 cases had been operated on 4 times and 1,7 ocassions. In all cases, a careful preoperative arrangement was made that included the local preparation of the skin and the reestablishment of the thoracoabdominal capacity by pneumoperitonea, which made possible the fascia to fascia facing without tension. The hernial rings measured more than 10 cm, with an average of 16. Cefazolin was used as a prophylactic antibiotic in all cases. There was no wound sepsis. No hernial relapse was observed with an average follow-up of 39.6 months. There have been no manifestations of rejection to the prosthetic material up to now. No immediate complications as seroma or hematoma of the surgical wound were reported, since a drainage was placed in the surgical zone in all cases(AU)

Fulguración eléctrica del haz de his: una nueva modalidad terapéutica para las taquiarritmias supraventriculares refractarias / Electric fulguration of the his bundle: a new treatment modality for refractory supraventricular tachiarrhythmias

Se realizó fulguración eléctrica del haz de His por catéter electrodo transvenoso, a ocho pacientes con taquiarritmias supraventriculares refractarias. En cada caso se ensayaron como mínimo tres fármacos antes del proceder, y la energia total aplicada por enfermo osciló entre 300 y 900 J. En cuatro pacientes se obtuvo un bloqueo auriculoventricular permanente, en tres la lesión del sistema de conducción o nódulo auriculoventricular no permitió la aparición de frecuencias ventriculares altas y en uno, la técnica no fue efectiva. Seis de los siete pacientes en quienes el proceder fue exitoso tienen implantados marcapasos cardíacos permenentes (cuatro de ellos autoprogramables en frecuencia). La evolución ha sido favorable en el tiempo observado y no ha habido complicaciones. Se concluye que la fulguración eléctrica del haz de His resultó una medida terapéutica eficaz en estos pacientes, y debe ser una de las primeras opciones a evaluar en enfermos con taquiarritmias supraventriculares refractarias