Thyroid hormone disorder and the heart: The role of cardiolipin in calcium handling.

NEW FINDINGS: What is the central question of this study? Do alterations in thyroid status affect haemodynamic parameters and echocardiographic measurements in the rat postnatal heart, and calcium handling, contractility, relaxation and cardiolipin content in isolated rat cardiomyocytes? What is the main finding and its importance? An imbalance in phospholipids of the mitochondrial membrane such as cardiolipin is related to defects in mitochondrial function. T3 -dependent cardiolipin signals contribute to the maintenance of mitochondrial homeostasis and involve Ca2+ handling, this pathway being more important in hypothyroidism. ABSTRACT: The objective of this study was to evaluate whether alterations in thyroid status affect (1) haemodynamic parameters and echocardiographic measurements in the rat postnatal heart, and (2) calcium handling, contractility, relaxation and cardiolipin content in isolated rat cardiomyocytes. Sprague-Dawley rats aged 2 months treated with T3 (hyperthyroid, 20 µg/100 g body weight) or 0.02% methimazole (hypothyroid, w/v) for 28 days. Heart function was evaluated by echocardiography. Measurements of mean arterial pressure (MAP), heart rate, Ca2+ transients, cardiomyocyte shortening, number of spontaneous contractions per minute and cardiolipin (CL) content were performed. Thyroid disorders were associated with changes in pacemaker activity without modifications of MAP. Thyroid disorder induced changes in left ventricular diameter which were correlated with modifications of cardiac contractility (altered cell shortening and sarcoplasmic reticulum Ca2+ content). Endocrine disorders altered cardiomyocyte relaxation (reduction in the time to 50% re-lengthening and the time to 50% Ca2+ decay). Thyroid disorder increased the number of spontaneous contractions per minute (an index of pro-arrhythmogenic behaviour). CL content was increased only in hypothyroid rats. Changes in CL content, CL composition and CL-protein interaction in mitochondria from hypothyroid animals are responsible for alterations of contractile and relaxation cardiac function. This mechanism may be not be involved in T3 -treated rats. Maintenance of euthyroidism is of crucial importance to preserve cardiac performance. An imbalance in relation to phospholipids of the mitochondrial membrane such as CL is related to defects in mitochondrial function. T3 -dependent CL signals contribute to the maintenance of mitochondrial homeostasis and involve Ca2+ handling, this pathway being more important in hypothyroidism.

Plasma polypyrrole implants recover motor function in rats after spinal cord transection.

We studied the use of three biocompatible materials obtained by plasma polymerization of pyrrole (PPy), pyrrole doped with iodine (PPy/I) and a copolymer formed with pyrrole and polyethylene glycol (PPy/PEG), implanted, separately, after a complete spinal cord transection in rats. Motor function assessed with the BBB scale and somatosensory evoked potentials (SEPs) in the implanted rats were studied. Results showed that the highest motor recovery was obtained in rats with PPy/I implants. They also showed a significant reduction in the latency of SEPs. Histological analyses showed no signs of implant rejection; on the contrary, implants based on PPy improved the SEPs conduction and motor function after lesion.

Rapid and simple determination of ciprofloxacin resistance in clinical strains of Escherichia coli.

We recently reported a simple new in situ diffusion assay, developed as a kit, to visualize DNA fragmentation in single bacterial cells. Use of this assay in a collection of 95 genetically unrelated Escherichia coli clinical strains resulted in correct identification of all of the isolates as resistant or susceptible to ciprofloxacin, consistent with the MIC results. This relevant information is obtained in 80 min.

Modulation of the outcome-related negativity associated with nicotine abstinence.

Cue-reactivity studies have shown that when consumers are exposed to a substance-related stimulus, potential tobacco use contributes significantly to craving and motivational drive. Although the motivational response to cues signaling tobacco availability has been widely studied, less is known about physiological reactivity to perceived cigarette availability. The aim of the present study was to examine the outcome-related negativity (ORN) evoked by stimuli that signal potential tobacco use in abstinent and sated smokers. The ORN is an event-related potential (ERP) component that reflects the emotional and motivational aspects of reward processing and is modulated by motivational value of reward. Thirty-two such smokers performed two distinct and comparable versions of a gambling task, under conditions of abstinence and satiation. The analysis of variance (ANOVA) analysis revealed that ORN amplitude was larger in abstinent than satisfied smokers on those trials in which tobacco could be used. Differences were significant at the Fz electrode (p < .01) and approached significance at the Cz (p = .061) and Pz (p = .059) electrodes. Moreover, ORN amplitude predicted subjective indices of desire and positive effects from smoking, but only in the abstinence condition. These findings suggest that perceived cigarette availability might influence physiological reactivity in smokers who are nicotine deprived. They also suggest that the ORN component may be related to the motivational mechanisms involved in addictive behavior.