Pharyngeal Pumping Assay v1

The pharynx is a is a neuromuscular pump found at the anterior end of the alimentary tract, consisting of 20 muscles and 20 neurons. A proper feeding rate in worms is coordinated by the precise timing of pharyngeal movements, with one complete cycle of synchronous contraction and relaxation of the corpus and terminal bulb termed a “pump”. A simple way to measure C. elegans feeding is to count how many times worms pump in a minute (pumps per minute). Movement of the grinder (in the terminal bulb) can easily be observed using a stereomicroscope, and because cycles of contraction/relaxation are synchronised along the pharynx, pumps per minute can be measured simply by counting grinder movements.

Differential Diagnosis of Parkinson Disease, Essential Tremor, and Enhanced Physiological Tremor with the Tremor Analysis of EMG

We investigate the differential diagnostic value of tremor analysis of EMG on Parkinson’s disease (PD), essential tremor (ET), and enhanced physiological tremor (EPT). Clinical data from 25 patients with PD, 20 patients with ET, and 20 patients with EPT were collected. The tremor frequency and muscle contraction pattern of the resting, posture, and 500 g and 1000 g overload were recorded. The frequency of PD tremor was 4–6 Hz, and the frequency of ET was also in this range; the frequency of EPT is 6–12 hz having some overlap with PD. The muscle contraction patterns of the ET and EPT group were mainly synchronous contraction, and the muscle contraction mode of the PD group was mainly alternating contraction. Having tremor latency from rest to postural position and having changes in tremor amplitude after mental concentration in PD might distinguish ET. Tremor analysis of EMG was able to distinguish PD from ET and EPT by varying the tremor frequency and muscle contraction pattern. It can also differentiate between PD and ET by the latency and concentration effect and ET and EPT by weight load effect.

Abstract 20350: Discordant Left Bundle Branch Block is Associated With Left Ventricular Dyssyncrhony at Cardiac Magnetic Resonance Imaging in Patients With Nonischemic Cardiomyopathy

LBBB is frequently linked to left ventricular (LV) dyssynchrony and adverse prognosis in HF. LBBB has been defined as concordant (cLBBB) or discordant (dLBBB), when associated in lead I and V5, V6 with a positive or negative T wave respectively. dLBBB has been associated with a worse clinical and prognostic profile in HF patients. We sought to evaluate association between different patterns of LV dV/dT curves at CMR, LBBB morphology, clinical correlates and prognostic role in patients with nonischemic systolic HF. Methods and Results: One hundred and fifteen consecutive patients with LBBB were submitted between 2004 and 2014 to a complete cardiological evaluation, including CMR with analysis of dV/dT curves of LV contraction, and follow-up for cardiac events. We distinguished two different patterns of global and segmental LV systole: a “narrow” pattern (NP) generated by synchronous contraction of wall segments; a “wide” pattern (WP), when delay in contraction between wall segments resulted in a prolungation of systolic peak with a flat or notched morphology. Fourteen patients presenting with normal LV dimensions and function all had cLBBB and NP, while out of 101 patients with HF, those with dLBBB (65%) presented with shorter QRS duration (p < .01) and higher level of NT-proBNP (p < .001). WP was observed more frequent in dLBBB patients (p < .003) as a mark of greater intraventricular dyssynchrony. According to systolic pattern, those with WP had higher levels of NT-proBNP, lower EF and higher LV volumes than those with NP, whereas no significant difference was found in QRS duration. At multivariate analysis only dLBBB (p=.006) and EF (p=.001) were independent predictors of WP. At Kaplan-Meier analysis, the presence of WP was associated with a worse prognosis considering a composite end-point of cardiac death, hospitalization for HF and ICD shock (p<.005). At Cox analysis only presence of WP (p = .029) and level of NT-proBNP (p= .004) were independent predictors. Conclusions: In nonischemic systolic HF patients with LBBB, presence of a WP at CMR dV/dT curves is associated with dLBBB, identifies greater LV dyssynchrony with possible major benefits from resynchronization therapy and is an independent prognosticator.

Electromechanical Coupling between Skeletal and Cardiac Muscle

Skeletal myoblasts form grafts of mature muscle in injured hearts, and these grafts contract when exogenously stimulated. It is not known, however, whether cardiac muscle can form electromechanical junctions with skeletal muscle and induce its synchronous contraction. Here, we report that undifferentiated rat skeletal myoblasts expressed N-cadherin and connexin43, major adhesion and gap junction proteins of the intercalated disk, yet both proteins were markedly downregulated after differentiation into myo-tubes. Similarly, differentiated skeletal muscle grafts in injured hearts had no detectable N-cadherin or connexin43; hence, electromechanical coupling did not occur after in vivo grafting. In contrast, when neonatal or adult cardiomyocytes were cocultured with skeletal muscle, ∼10% of the skeletal myotubes contracted in synchrony with adjacent cardiomyocytes. Isoproterenol increased myotube contraction rates by 25% in coculture without affecting myotubes in monoculture, indicating the cardiomyocytes were the pacemakers. The gap junction inhibitor heptanol aborted myotube contractions but left spontaneous contractions of individual cardiomyocytes intact, suggesting myotubes were activated via gap junctions. Confocal microscopy revealed the expression of cadherin and connexin43 at junctions between myotubes and neonatal or adult cardiomyocytes in vitro. After microinjection, myotubes transferred dye to neonatal cardiomyocytes via gap junctions. Calcium imaging revealed synchronous calcium transients in cardiomyocytes and myotubes. Thus, cardiomyocytes can form electromechanical junctions with some skeletal myotubes in coculture and induce their synchronous contraction via gap junctions. Although the mechanism remains to be determined, if similar junctions could be induced in vivo, they might be sufficient to make skeletal muscle grafts beat synchronously with host myocardium.