Smooth muscle myosin light chain kinase is transiently expressed in skeletal muscle during embryogenesis and muscle regeneration both in vivo and in vitro

Byusing a polyclonal antibody raised against smooth muscle MyosinLight Chain Kinase of adult chicken we show that the 135 kDasmooth muscle Myosin Light Chain Kinase isoform is present inneonatal and regenerating rat skeletal muscle, as well as inadult atrial myocardium. No reaction was evident in adultskeletal muscle fibres. In neonatal and in early regeneratingmuscle smooth muscle Myosin Light Chain Kinase is associated withembryonic myosin as revealed by their co-presence in musclefibres. Experiments in vitro show the same results in myotubes.In atrial myocardium there is a patchy positivity in certaingroup of myocytes. Immunoblotting experiments show in muscle cellcultures, in neonatal and in regenerating skeletal muscle aprotein band with electrophoretic mobility corresponding to thatof smooth muscle Myosin Light Chain Kinase. These results suggestthat the expression of smooth muscle Myosin Light Chain Kinase isnot fully tissue-specific and that regulation of the contractilemachinery could be different during myogenesis and in adulthood,in relation to the peculiar dynamic characteristics of developingmuscles     

Genetic and population structure of four Sardinian villages

1. Data on microgeographic population structure on four neighbouring villages of Sardinia island (Italy) are presented and discussed.
2. Two villages are located in the lowlands where malaria from Plasmodium falciparum was endemic until the eradication of paludism. The other two villages are located in the highlands and they were malaria-free because of the altitude.
3. Census data, inbreeding, migration matrices and surname distributions have been collected. The genetic differentiation of the four villages, tested for 31 genetic polymorphisms (106 alleles), is only in part compatible with migration rates inferred from demographic data.
4. The possible adaptive nature of some genetic markers with respect to malarial resistance is discussed. Ambiguous results from population genetics quantitative methods do not support definite answers.     

Induction of supraventricular tachyarrhythmia at rest and during exercise with transoesophageal atrial pacing in the electrophysiological evaluation of asymptomatic athletes with Wolff-Parkinson-White Syndrome

Even today there is controversy as regards the best approachto asymptomatic or slightly symptomatic athletes with the WPMsyndrome as regards fitness for sports activity, especiallyin some countries where the doctor is responsible for certifyingsports fitness. This study concerns 84 asymptomatic or slightlysymptomatic athletes (66 males, 18 females, mean age 21.7 years,range 12–44 years) who underwent a stimulation protocolthe end-point of which was the induction of atrial fibrillation(or, if not possible, atrial tachyarrhythmia) in the basal stateand during bicycle stress test with transesophageal atrial pacing.The 81 athletes in whom the end-point was reached were dividedinto two groups: Group I includes the 32 athletes with the shortestR–R interval between pre-excited beats 240 ms in thebasal state and /or 210 ms during bicycle ergometer test, GroupII includes the other 49 patients. The evaluation during exercisewas not carried out in four athletes because of serious haemodynamiccompromise due to the arrhythmia induced in the basal state.Only 21/32 athletes would have been included in Group I if onlyevaluated in the basal state. In 30/81 athletes (37%), there was discrepancy between the resultof stimulation and the result of the usual non-invasive evaluation(Holter monitoring, ergometric stress test, ajmaline test).On average, 40 min are required for the performance of the studyprotocol except when the induced arrhythmia lasts more than5 min. The follow-up of the Group I athletes ranged from 10 to 36 months(mean 20.5 months); three athletes became symptomatic and intwo of these the clinical arrhythmia was like the one induced. On the basis of our results, we conclude that the inductionof atrial fibrillation under stress is useful in screening athleteswith WPM syndrome; and, as it is simple to perform and economical(in time, equipment and staff), we regard this protocol as fundamentalfor the electrophysiological evaluation of athletes with Wolff–Parkinson–Whitesyndrome.