Dyssynchronous Ventricular Activation in Asymptomatic Wolff-Parkinson-White Syndrome: A Risk Factor for Development of Dilated Cardiomyopathy

A subset of children and adults with Wolff-Parkinson-White (WPW) syndrome develop dilated cardiomyopathy (DCM). Although DCM may occur in symptomatic WPW patients with sustained tachyarrhythmias, emerging evidence suggests that significant left ventricular dysfunction may arise in WPW in the absence of incessant tachyarrhythmias. An invariable electrophysiological feature in this non-tachyarrhythmia type of DCM is the presence of a right-sided septal or paraseptal accessory pathway. It is thought that premature ventricular activation over these accessory pathways induces septal wall motion abnormalities and ventricular dyssynchrony. LV dyssynchrony induces cellular and structural ventricular remodelling, which may have detrimental effects on cardiac performance. This review summarizes recent evidence for development of DCM in asymptomatic patients with WPW, discusses its pathogenesis, clinical presentation, management and treatment. The prognosis of accessory pathway-induced DCM is excellent. LV dysfunction reverses following catheter ablation of the accessory pathway, suggesting an association between DCM and ventricular preexcitation. Accessory pathway-induced DCM should be suspected in all patients presenting with heart failure and overt ventricular preexcitation, in whom no cause for their DCM can be found.     

Determination of serum cholinesterase activity and dibucaine numbers by an amperometric choline sensor

Serum cholinesterase activity and the dibucaine numbers have been determined by using a hydrogen peroxide electrode and the enzyme choline oxidase immobilized on a nylon net. The analysis procedure is extremely simple and very fast allowing 30 cholinesterase determinations per hour. Both cholinesterase activity and dibucaine number measurements could be performed in 5 min and by using serum samples of only 10 microliters. When used in sera the probe showed no interference from electroactive compounds present in blood, and also showed good stability and reproducibility. These features make this sensor appropriate for continuous extracorporeal circuit blood monitoring of succinylcholine during surgery.     

Cytogenetic markers for the characterization of Capsicum annuum L. cultivars

Karyotypic studies with conventional staining have been unsuccessful due to the uniformity of Capsicum chromosomes. In this study, we found diagnostic chromosome characters that permit to characterize cultivars; this is the first cytological characterization of both rDNAs (18S and 5S) in a species of Capsicum using a genus-specific probe and the most exhaustive in C. annuum to date. The heterochromatic banding patterns enabled us to identify cultivars, and fluorescent in situ hybridization (FISH) showed one 5S rDNA locus largely conserved within the cultivars, whereas high variation in the number of 18S rDNA loci was observed. One of the most obvious differences is the presence of an additional active nucleolar organizer region in pair #12 and the dispersal of inactive 18S rDNA signals. These results indicate that fluorochrome banding together with silver impregnation and FISH procedures are very useful for the identification of chromosomes and the interpretation of chromosomal variation between cultivars. The functional role of this variation is still uncertain, but our results show that copy number variation of repetitive DNA during the course of evolution might provide an excellent experimental system for studying genome rearrangements accompanying functional divergence in domesticated C. annuum.