Quantification of cardiomyocyte contraction based on image correlation analysis.

Quantification of cardiomyocyte contraction is usually obtained by measuring globally cell shortening from the displacement of cell extremities. We developed a correlation-based optical flow method, which correlates the whole-cell temporal pattern with a precise quantification of the intracellular strain wave at the sarcomeres level. A two-dimensional image correlation analysis of cardiomyocytes phase-contrast images was developed to extract local cell deformations from videomicroscopy time-lapse sequences. Test images, synthesized from known intensity displacement fields, were first used to validate the method. Intracellular strain fields were then computed from videomicroscopy time-lapse sequences of single adult and neonatal cardiomyocytes. The propagation of the sarcomeres contraction-relaxation wave during cell contraction has been successfully quantified. The time-varying patterns of intracellular displacement were obtained accurately, even when cardiomyocyte bending occurred in pace with contraction. Interestingly, the characterization of the successive 2D displacement fields show a direct quantification of the variation with time of intracellular strains anywhere in the cell. The proposed method enables a quantitative analysis of cardiomyocyte contraction without requiring wave tracking with the use of fluorescent calcium probes. Thus, our algorithmic approach provides a fast and efficient tool for analyzing the correlation between global cell dynamical behavior and mechanosensitive intracellular processes.

A single session of repetitive transcranial magnetic stimulation of the prefrontal cortex reduces cue-induced craving in patients with gambling disorder.

BACKGROUND: Gambling disorder (GD) is common and disabling addictive disorder. In patients with substance use disorders, the application of repetitive transcranial magnetic stimulation (rTMS) over the dorsolateral prefrontal cortex (DLPFC) offers promise to alleviate craving. We hypothesized that applying real compared to sham rTMS over the left DLPFC would reduce gambling craving in patients with GD. METHODS: In a randomized sham-controlled crossover design, 22 treatment-seeking patients with GD received real or sham treatment with high frequency rTMS over the left DLPFC followed a week later by the other type of treatment. Before and after each rTMS session, participants rated their gambling craving (from 0 to 100) before and after viewing a gambling video used as a cue. We used the Yale-Brown Obsessive Compulsive Scale adapted for Pathological Gambling to assess gambling behavior before and 7 days after each rTMS session. RESULTS: As compared to sham (mean +0.74; standard deviation±3.03), real rTMS significantly decreased cue-induced craving (-2.12±3.39; F(1,19)=4.87; P=0.04; partial η2=0.05; 95% CI: 0.00-0.21). No significant effect of rTMS was observed on gambling behavior. CONCLUSIONS: Patients with GD reported decreased cue-induced craving following a single session of high frequency rTMS applied over the left DLPFC. Further large randomized controlled studies are needed to determine the usefulness of rTMS in GD.