Modulation du transport du Ca²+ et du Na+ cytosolique et nucléaire par la taurine dans les cellules ventriculaires cardiaques

Abstract: Taurine has been reported to produce (i) a positive inotropic effect in heart muscle, (ii) beneficial effects in treatment of congestive heart failure and (iii) protective effects against Ca2+ overload. The objective of this work was to determine the short and long-term effect of normal physiological concentration of taurine on [Ca2+]i and [Na+]i of ventricular heart cells, and to determine whether long-term exposure to normal concentration of taurine ( 1mM) block and/or prevent Ca2+ overload in heart cells induced by sustained depolarization of the cell membrane. Using the fura-2 Ca2+ fluorescence microfluorometry and imaging techniques as well as fluo-3 and Na+-Green 3-D confocal microscopy measurement of free Ca2+ and Na+ respectively, short-term exposure to normal physiological concentration of taurine (1 mM) had no effect on the steady-state basal total [Ca2+]i and [Na+]i in isolated ventricular heart cells. However, exposure to relatively high concentrations of taurine (10-80 mM) induced a significant concentration-dependent sustained increase of the resting steady-state basal total [Ca2+]i and [Na+]i of ventricular heart cells. Pretreatment with β-alanine, a blocker of taurine- Na+ cotransporter, was found to block taurine-induced dose-dependent increase in [Ca2+]i in heart cells. Also a low concentration of the Na+/ Ca2+-exchanger blocker, CBDBMB (an amiloride derivative), was found to attenuate the increase in total [Ca2+]i induced by short-term treatment with taurine. Thus, the increase of basal total [Na+]i by short-term treatment with taurine could be due to Na+ entry through the taurine- Na+ cotransporter and the increase in the basal steady-state [Ca2+]i could then be due to an increase in [Na+]i which in tum favors sarcolemrnal Ca2+ influx through the Na+/ Ca2+-exchanger. Thus, taurine at relatively high concentration may exert a positive inotropic effect by such mechanism. Using the same techniques, it was found that the increase of basal total intracellular Ca2+·and Na+ levels by short-term treatment with high concentration of taurine ( ≥ 5mM) is mainly nuclear. The increase of basal nuclear sustained Na+ by taurine could be due to possible presence of a taurine- Na+ cotransporter on the nuclear membrane whereas the increase of nuclear sustained Ca2+ could be due to cytosolic Ca2+ buffering by the nucleus. Long-term exposure of heart cells to normal physiological concentration of taurine ( 1 mM) was found to decrease both cytosolic and nuclear sustained Ca2+ as well as nuclear Na+ without affecting cytosolic Na+. Moreover, long-term exposure to taurine was found to prevent nuclear increase of Ca2+ induced by permanent depolarization of heart cells with high [K+]o . This preventive effect of taurine on nuclear Ca2+ overload was associated with an increase of both cytosolic and nuclear Na+. Thus, the effect of long-term exposure to taurine on intranuclear Ca2+ overload in heart cells seems to be mediated via stimulation ofsarcolemma and nuclear Ca2+ outflow through the Na+/ Ca2+-exchanger. The fact that taurine failed to block the observed sustained elevation of nuclear Ca2+ pre-induced by sustained long-term depolarization of the membrane suggests that this amino acid possesses only a preventive effect on nuclear Ca2+ overload. [Symboles non conformes]Il est rapporté que Ia taurine produit (i) un effet inotrope positif dans le muscle cardiaque, (ii) des effets bénéfiques dans le traitement de l'insuffisance cardiaque et (iii) des effets protecteurs contre la surcharge du Ca2+. L'objectif de cette étude est de déterminer l'effet à long-terme et à court-terme de la taurine a une concentration physiologique normale sur [Ca2+]i et [Na+]i sur des cellules ventriculaires cardiaques et de déterminer si le traitement à long-terme avec une concentration normale de taurine (1mM) bloque et/ou empêche Ia surcharge calcique induite par une dépolarisation soutenue de la membrane cellulaire. En utilisant les techniques de microfluometrie et d'imagerie avec la sonde calcique fura-2 et la méthode de mesure en 3-D a l'aide de Ia microscopie confocale et les sondes fluo-3 et Na+-Green pour le Ca2+ et le Na+ respectivement, la présence de taurine à une concentration physiologique normale a court-terme, n'a pas d'effet sur le niveau basal total du [Ca2+]i et [Na+]i chez les cellules cardiaques ventriculaires isolées. Cependant, I'ajout de Ia taurine à des concentrations relativement élevées ( 10-80 mM) a induit une augmentation soutenue significative concentration-dépendente du niveau basal total du [Ca2+]i et [Na+]i des les cellules cardiaques. Le pré-traitement avec de la β-alanine, un bloqueur du co-transporteur taurine- Na+, a bloqué l'augmentation du [Ca2+]i induite par Jes concentrations croissantes de taurine dans les cellules cardiaques. De même, une faible concentration du bloqueur de l'échangeur Na+/ Ca2+ , CBDBMB (dérivé de l'amiloride), a atténué I' augmentation totale du [Ca2+]i induite par le traitement avec la taurine a court-terme. L'augmentation du niveau basal total du [Na+]i par le traitement à court-terme avec la taurine peut être due à l'entrée du Na+ à travers le co-transporteur taurine- Na+ et l'augmentation du niveau basal du [Ca2+]i peut être due alors à l'augmentation du [Na+]i qui favorise l'influx calcique à travers le sarcolemme via l'échangeur Na+/ Ca2+ . La taurine exerce alors un effet inotrope positif par un mécanisme semblable. En utilisant les mêmes techniques, il a été démontré que I'élévation du niveau basal total intracellulaire du Ca2+ et Na+ par le traitement à court-terme avec des concentrations élevées de taurine ( ≥ 5mM) est principalement nucléaire. L'augmentation soutenue du niveau basal nucléaire de Na+ par la taurine peut être due à Ia présence possible du co-transporteur taurine- Na+ sur la membrane nucléaire, tandis que l'augmentation soutenue du Ca2+ nucléaire peut être due à l'effet tampon calcique du noyau. Le traitement des cellules cardiaques a long-terme avec une concentration physiologique normale de taurine a diminué le Ca2+ cytosolique et nucléaire ainsi que le Na+ nucléaire sans affecter le Na+ cytosolique. De plus, le traitement à long-terme avec la taurine a empêché l'augmentation nucléaire du Ca2+ induite par la dépolarisation soutenue des cellules cardiaques avec une concentration élevée de [K+]o. Cet effet préventif de la taurine sur la surcharge calcique nucléaire était associé à l'augmentation du Na+ cytosolique et nucléaire. L' effet du traitement à long-terme avec la taurine sur la surcharge du Ca2+ intranucleaire dans les cellules cardiaques se fait suite à la sortie du Ca2+ à travers la membrane nucléaire et le sarcolemme via la stimulation de I' échangeur Na+/ Ca2+ Le fait que la taurine n'a pas bloqué l'élévation soutenue du Ca2+ nucléaire observée pré-induite par la dépolarisation soutenue de la membrane à long-terme suggère que cet acide aminé possède uniquement un effet préventif sur la surcharge du Ca2+ nucléaire. [Symboles non conformes

Depression, anxiety, and smartphone addiction in university students- A cross sectional study

<div><p>Objectives</p><p>The study aims to assess prevalence of smartphone addiction symptoms, and to ascertain whether depression or anxiety, independently, contributes to smartphone addiction level among a sample of Lebanese university students, while adjusting simultaneously for important sociodemographic, academic, lifestyle, personality trait, and smartphone-related variables.</p><p>Methods</p><p>A random sample of 688 undergraduate university students (mean age = 20.64 ±1.88 years; 53% men) completed a survey composed of a) questions about socio-demographics, academics, lifestyle behaviors, personality type, and smartphone use-related variables; b) 26-item Smartphone Addiction Inventory (SPAI) Scale; and c) brief screeners of depression and anxiety (PHQ-2 and GAD-2), which constitute the two core DSM-IV items for major depressive disorder and generalized anxiety disorder, respectively.</p><p>Results</p><p>Prevalence rates of smartphone-related compulsive behavior, functional impairment, tolerance and withdrawal symptoms were substantial. 35.9% felt tired during daytime due to late-night smartphone use, 38.1% acknowledged decreased sleep quality, and 35.8% slept less than four hours due to smartphone use more than once. Whereas gender, residence, work hours per week, faculty, academic performance (GPA), lifestyle habits (smoking and alcohol drinking), and religious practice did not associate with smartphone addiction score; personality type A, class (year 2 vs. year 3), younger age at first smartphone use, excessive use during a weekday, using it for entertainment and not using it to call family members, and having depression or anxiety, showed statistically significant associations with smartphone addiction. Depression and anxiety scores emerged as independent positive predictors of smartphone addiction, after adjustment for confounders.</p><p>Conclusion</p><p>Several independent positive predictors of smartphone addiction emerged including depression and anxiety. It could be that young adults with personality type A experiencing high stress level and low mood may lack positive stress coping mechanisms and mood management techniques and are thus highly susceptible to smartphone addiction.</p></div

Association between total SPAI score and anxiety score, as assessed by multiple linear regression^*.

<p>Association between total SPAI score and anxiety score, as assessed by multiple linear regression^{<a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0182239#t005fn001" target="_blank">*</a>}.</p

Associations between smartphone addiction level (total SPAI score) and participants' characteristics.

<p>Associations between smartphone addiction level (total SPAI score) and participants' characteristics.</p

Characteristics of study participants (n = 688).

<p>Characteristics of study participants (n = 688).</p

Prevalence of smartphone addiction (SPAI) symptoms among study participants (n = 688).

<p>Prevalence of smartphone addiction (SPAI) symptoms among study participants (n = 688).</p

Adherence to the Mediterranean diet among adults in Mediterranean countries:a systematic literature review

BACKGROUND AND AIM: While the Mediterranean diet (MD) is promoted in non-Mediterranean countries, inhabitants of Mediterranean countries seem to be shifting away from this healthy diet. The aim of this study is to provide an overview of MD adherence in the general adult population of Mediterranean countries. METHODS: A systematic review was conducted following the PRISMA 2020 (Preferred Reporting Items for Systematic Review and Meta-Analysis) guidelines and registered in the Prospero database (CRD42020189337). Literature was searched in PubMed, Web of Science and PsycINFO databases for studies published from 2010 up to and including 2021. The following inclusion criteria were used: age 18 years and older, sample size > 1000 participants, and using a validated MD adherence score. Studies that only included participants with nutrition-related or other severe chronic disorders, as well as studies that only included specific subpopulations (e.g., pregnant women), were excluded in order to focus on the general adult population. A quality analysis of the included studies was done using the NCCMT scale. RESULTS: A total of 50 studies were included. The number of participants in the included studies ranged between 1013 and 94,113. Most of the included studies pertained to the European Mediterranean countries, with fewer studies from the Middle Eastern and North African Mediterranean countries. The vast majority of the included studies reported low or moderate MD adherence, both based on the mean adherence as well as the low or moderate adherence category often being the most prevalent. There were no clear differences noted between sex and age groups. The quality assessment generally showed weak or moderate scores. CONCLUSIONS: Mediterranean populations have been showing moderate adherence to MD in the past 10 years, indicating room for improving adherence to the MD in countries of its origin