Effectiveness of a secondary prevention protocol for occupational contact dermatitis.

BACKGROUND: Occupational skin diseases are often responsible for sick leave or job changes, affect mostly young subjects, are costly to society and have been reported as significant predictor of unemployment. OBJECTIVES: To assess, over time, the course of occupational hand dermatitis (OHD) after a specific training, by means of follow-up visits and TEWL measurement, to evaluate skin barrier integrity and if preventive measures for hand skin care provided may influence the course of the disease. METHODS: Workers with a diagnosis of OHD from January 2011 to December 2013 were contacted by telephone, filled in a questionnaire (NOSQ-2002) and were invited to a training course on prevention of skin dermatitis, and to a new clinical evaluation with TEWL measurement. Workers who joined the training programme were asked to undergo a new evaluation after 3 months. A total of 65 subjects without contact dermatitis were recruited as control group. RESULTS: One hundred and one subjects from 143 workers, who were contacted, filled in the questionnaire. Sixty-five of them followed the training course and underwent a new clinical evaluation withTEWL measurements. Ongoing symptoms of subjects decreased from 60.0% to 42.3% 3 months after the training, and the subgroup which strictly adhered to the recommendations given achieved better results (61.9% of symptoms improvement when compared to 29.0% obtained in subjects with partial adhesion to the protocol). TEWL values changed from 21.3 ± 9.6 to 18.6 ± 7.2 g/m²/h (P = 0.001) on the hands and from 16.6 ± 9.0 to 10.5 ± 4.6 g/m²/h (P = 0.001) on the forearm, confirming the skin barrier improvement. CONCLUSIONS: Our secondary prevention intervention was effective, leading to a reduction in clinical signs of dermatitis. TEWL measurement is a useful tool to evaluate skin integrity, mostly in apparently healthy skin, which may have a compromised barrier function, resulting in an exacerbation of the dermatitis.

Mitochondrial reactive oxygen species (ROS) as signaling molecules of intracellular pathways triggered by the cardiac renin-angiotensin II-aldosterone system (RAAS).

Mitochondria represent major sources of basal reactive oxygen species (ROS) production of the cardiomyocyte. The role of ROS as signaling molecules that mediate different intracellular pathways has gained increasing interest among physiologists in the last years. In our lab, we have been studying the participation of mitochondrial ROS in the intracellular pathways triggered by the renin-angiotensin II-aldosterone system (RAAS) in the myocardium during the past few years. We have demonstrated that acute activation of cardiac RAAS induces mitochondrial ATP-dependent potassium channel (mitoKATP) opening with the consequent enhanced production of mitochondrial ROS. These oxidant molecules, in turn, activate membrane transporters, as sodium/hydrogen exchanger (NHE-1) and sodium/bicarbonate cotransporter (NBC) via the stimulation of the ROS-sensitive MAPK cascade. The stimulation of such effectors leads to an increase in cardiac contractility. In addition, it is feasible to suggest that a sustained enhanced production of mitochondrial ROS induced by chronic cardiac RAAS, and hence, chronic NHE-1 and NBC stimulation, would also result in the development of cardiac hypertrophy.

The positive inotropic effect of endothelin-1 is mediated by mitochondrial reactive oxygen species.

We have previously demonstrated the participation of reactive oxygen species (ROS) in the positive inotropic effect of a physiological concentration of Angiotensin II (Ang II, 1 nM). The objective of the present work was to evaluate the role and source of ROS generation in the positive inotropic effect produced by an equipotent concentration of endothelin-1 (ET-1, 0.4 nM). Isolated cat ventricular myocytes were used to measure sarcomere shortening with a video-camera, superoxide anion (()O(2)(-)) with chemiluminescence, and ROS production and intracellular pH (pH(i)) with epifluorescence. The ET-1-induced positive inotropic effect (40.4+/-3.1%, n=10, p<0.05) was associated to an increase in ROS production (105+/-29 fluorescence units above control, n=6, p<0.05). ET-1 also induced an increase in ()O(2)(-) production that was inhibited by the NADPH oxidase blocker, apocynin, and by the blockers of mitochondrial ATP-sensitive K(+) channels (mK(ATP)), glibenclamide and 5 hydroxydecanoic acid. The ET-1-induced positive inotropic effect was inhibited by apocynin (0.3 mM; 6.3+/-6.6%, n=13), glibenclamide (50 microM; 8.8+/-3.5%, n=6), 5 hydroxydecanoic acid (500 microM; 14.1+/-8.1, n=9), and by scavenging ROS with MPG (2 mM; 0.92+/-5.6%, n=8). ET-1 enhanced proton efflux (J(H)) carried by the Na(+)/H(+) exchanger (NHE) after an acid load, effect that was blocked by MPG. Consistently, the ET-induced positive inotropic effect was also inhibited by the NHE selective blocker HOE642 (5 microM; 9.37+/-6.07%, n=7). The data show that the effect of a concentration of ET-1 that induces an increase in contractility of about 40% is totally mediated by an intracellular pathway triggered by mitochondrial ROS formation and stimulation of the NHE.