An ecological and theoretical deconstruction of a school-based obesity prevention program in Mexico

BACKGROUND: Ecological intervention programs are recommended to prevent overweight and obesity in children. The National Institute of Public Health (INSP) in Mexico implemented a successful ecological intervention program to promote healthy lifestyle behaviors in school age children. This study assessed the integration of ecological principles and Social Cognitive Theory (SCT) constructs in this effective school-based obesity prevention program implemented in 15 elementary schools in Mexico City. METHODS: Two coders applied the Intervention Analysis Procedure (IAP) to “map” the program’s integration of ecological principles. A checklist gauged the use of SCT theory in program activities. RESULTS: Thirty-two distinct intervention strategies were implemented in one setting (i.e., school) to engage four different target-groups (students, parents, school representatives, government) across two domains (Nutrition and Physical Activity). Overall, 47.5% of the strategies targeted the school infrastructure and/or personnel; 37.5% of strategies targeted a key political actor, the Public Education Secretariat while fewer strategies targeted parents (12.5%) and children (3%). More strategies were implemented in the Nutrition domain (69%) than Physical Activity (31%). The most frequently used SCT construct within both intervention domains was Reciprocal Determinism (e.g., where changes to the environment influence changes in behavior and these behavioral changes influence further changes to the environment); no significant differences were observed in the use of SCT constructs across domains. CONCLUSIONS: Findings provide insight into a promising combination of strategies and theoretical constructs that can be used to implement a school-based obesity prevention program. Strategies emphasized school-level infrastructure/personnel change and strong political engagement and were most commonly underpinned by Reciprocal Determinism for both Nutrition and Physical Activity

Étude des effets de contraintes dynamiques sur l'organisation d'échafaudage collagène-cellules

Au cours des trente dernières années, l’ingénierie du tissu vasculaire a connu un essor considérable dû à un besoin clinique important de greffons vasculaires adéquats pour le remplacement d’artères de faible diamètre. En effet, les greffes autologues ou synthétiques actuels de faible diamètre s’accompagnent souvent d’une défaillance à l’intérieur de 5 à 10 ans. Malgré les efforts injectés dans les dernières années, la translation vers la clinique d’artères régénérées ne connait pas les résultats escomptés. L’un des défis majeur dans l’ingénierie tissulaire est le contrôle des fonctions cellulaires qui dicte la maturation des constructions. De nombreuses études ont été menées sur la réponse des cellules musculaires lisses (abréviation en anglais : SMC désignant «smooth muscle cell») en 2D sous contrainte cyclique, mais peu ont examiné l'effet de la contrainte cyclique sur les SMC en 3D afin d'optimiser les stratégies de contrôle de bioréacteurs pour la maturation et régénération des tissus. Ainsi, ce projet de recherche vise à faire l’étude des effets de stimuli mécaniques cycliques sur des échafaudages cellularisés de collagène. Le collagène a été utilisé comme échafaudage dû à ses excellentes propriétés biologiques et aussi car il est présent dans la paroi des artères physiologiques. Un système permettant d’imposer des stimuli mécaniques cycliques en 2D aux constructions 3D de collagène cellularisées a donc été développé. Les contraintes cycliques ont révélé une orientation préférentielle des cellules dans le sens de la contrainte, ainsi qu’une orientation des fibrilles de collagène dans ce même sens par les cellules. De plus, le remodelage effectué par les cellules a permis d’augmenter les propriétés viscoélastiques de la construction et d’obtenir un comportement mécanique à la relaxation de contrainte semblable aux veines saphènes. Les cellules ont également démontré une désensibilisation face aux contraintes cycliques. Cette recherche a ainsi permis de répondre à certaines questions reliées aux comportements cellulaires dans un environnement 3D sous condition de stimulation mécanique. L’approfondissement des connaissances des comportements cellulaires en environnement 3D sous contrainte cyclique demeurent un défi clé dans l’obtention d’artères régénérées ayant des propriétés physiologiques similaires à celles d’artères natives.In the last thirty years, vascular tissue engineering has emerged as an important field in tissue engineering due to a significant clinical need for adequate vascular graft for replacement of small diameter artery. Indeed, the current autologous or synthetic grafts of small diameter present a high failure rate within 5 to 10 years. Despite the efforts injected in the recent years, the clinical translation of engineered artery constructs is far from being successful. One of the challenges encountered in tissue engineering is the control of cellular functions that dictates the maturation of tissue engineering constructs. Furthermore, numerous studies have been conducted on the response of smooth muscle cells (SMC) in 2D under cyclic strain, but a few have examined the effect of cyclic strain on SMCs in 3D to optimize the control strategies of bioreactors for tissue maturation and generation. Thus, this research project aims to study the effects of cyclic mechanical stimuli on cellularised collagen scaffolds. Collagen has been used as a scaffold due to its excellent biological properties and since it is found in the wall of physiological arteries. A system for imposing cyclic mechanical stimuli in 2D to 3D cellularised collagen constructs was therefore developed. The cyclic stresses revealed a preferential orientation of the cells in the direction of the strain, as well as an orientation by the cells of the collagen fibrils in the same direction. Moreover, the remodeling performed by the cells led to an improvement of the viscoelastic properties of the construct and to a mechanical behavior similar to the saphenous vein under stress-relaxation. The cells also shown a desensitization to cyclic mechanical stimuli. Thus, this research allowed to answer some of the questions related to cellular behavior in a 3D environment under mechanical stimulation. Deepening our knowledge of cell behavior in 3D environment under cyclic mechanical stimuli remains a key challenge in obtaining regenerated artery with similar physiological properties than native arteries

Validation of reference genes for real-time PCR of cord blood mononuclear cells, differentiating endothelial progenitor cells, and mature endothelial cells

In the last ten years, endothelial progenitor cells (EPCs) have gained interest as an attractive cell population in regenerative medicine for vascular applications. This population is defined as the precursor of endothelial mature cells (ECs) through a process of differentiation. To our knowledge, no single marker can be used to discriminate them from mature ECs. To effectively study their differentiation kinetics, gene expression must be assessed. Quantitative real-time PCR (RT-qPCR) is widely used to analyze gene expression. To minimize the impact of variances from RT-qPCR, a rigorous selection of reference genes must be performed prior to any experiments due to variations in experimental conditions. In this study, CD34+ mononuclear cells were extracted from human cord blood and differentiated into EPCs after seeding for a maximum period of 21 days. To choose the best combinations of reference genes, we compared the results of EPCs, CD34+ mononuclear cells, and mature endothelial cells to ensure that the differentiation kinetics did not affect the expression of our selected reference genes. The expression levels of seven genes, namely, YWHAZ, GAPDH, HPRT1, RPLP0, UBC, B2M, and TBP were thus compared. The algorithms geNorm, NormFinder, BestKeeper, and the Comparative ΔCt method were employed to assess the expression of each candidate gene. Overall results reveal that the expression stability of reference genes may differ depending on the statistical program used. YWHAZ, GAPDH, and UBC composed the optimal set of reference genes for the gene expression studies performed by RT-qPCR in our experimental conditions. This work can thus serve as a starting point for the selection of candidate reference genes to normalize the levels of gene expression in endothelial progenitor cell population

Perceived community environment and physical activity involvement in a northern-rural Aboriginal community

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The Physical Activity Promotion Environment In Mexican Health Care Settings

Purpose: The health care environment is recognized as a promising setting in which to promote physical activity (PA). Nearly 40% of Mexican adults are inactive and whether Mexican health care environments are promoting PA is unknown. The purpose of this study was to describe and compare the PA promotion environment in Guadalajara, Mexico. Methods: Forty primary care clinics and hospitals from the three health care systems in Guadalajara were sampled: 15 from the Secretary of Health, 14 from the Social Security Institutes and 11 from the private sector. A tool for measuring the PA environment of health care settings, including the availability of written PA materials, was developed. Face validity and inter-rater reliability of the tool were established (kappa=.75). Level of care (primary, secondary, and tertiary), number of floors and type of health care system of each clinic and hospital were also recorded. The tool was then used to assess the availability, accessibility, visibility, signage, cleanliness, and safety of all stairs, elevators, and green spaces at each health care setting and to record the presence of written PA materials including posters, brochures, leaflets, flyers, articles, and ‘cartels’ (hand-made posters) in the foyer and one waiting room of each clinic and hospital. Results: Thirty (75%) clinics and hospitals had stairs, 17 (42%) had elevators, 22 (55%) had green spaces and 11 (28%) had promotional PA materials (only posters or cartels). The availability of PA posters/cartels was significantly associated with health care system type (X2(2)=8.11, p\u3c.05) and with level of care (X2(2)=6.68, p\u3c.05), where primary care clinics from the Secretary of Health had significantly more PA promotional materials than clinics and hospitals from the other two systems. The health care PA environment score reflected by the stair, elevator, and green space indicators was not significantly different between the three Mexican health care systems (p\u3e.05); the score was low across the three systems (Mean=3.7, SD=2.7, Range=-2-10). Conclusions: Mexican health care settings are not PA friendly. Interventions to enhance the PA promotion environment in the three Mexican health care systems are needed to reach inactive patients

Electric potential across epidermis and its role during wound healing can be studied by using an in vitro reconstructed human skin

Background : After human epidermis wounding, transepithelial potential (TEP) present in nonlesional epidermis decreases and induces an endogenous direct current epithelial electric field (EEF) that could be implicated in the wound re-epithelialization. Some studies suggest that exogenous electric stimulation of wounds can stimulate healing, although the mechanisms remain to be determined. The Problem : Little is known concerning the exact action of the EEF during healing. The mechanism responsible for TEP and EEF is unknown due to the lack of an in vitro model to study this phenomenon. Basic Science Advances : We carried out studies by using a wound created in a human tissue-engineered skin and determined that TEP undergoes ascending and decreasing phases during the epithelium formation. The in vitro TEP measurements over time in the wound were corroborated with histological changes and with in vivo TEP variations during porcine skin wound healing. The expression of a crucial element implicated in Na+ transport, Na+/K+ ATPase pumps, was also evaluated at the same time points during the re-epithelialization process. The ascending and decreasing TEP values were correlated with changes in the expression of these pumps. The distribution of Na+/K+ ATPase pumps also varied according to epidermal differentiation. Further, inhibition of the pump activity induced a significant decrease of the TEP and of the re-epithelization rate. Clinical Care Relevance : A better comprehension of the role of EEF could have important future medical applications regarding the treatment of chronic wound healing. Conclusion : This study brings a new perspective to understand the formation and restoration of TEP during the cutaneous wound healing process