Myometrial contractility and gap junctions : an experimental study in chronically instrumented ewes

This thesis presents a combined approach using ultrastructural, electrophysiological and endocrinological methods to investigate factors which control myometrial contractility in vivo in the period of time around parturition, in an attempt to integrate various recent research findings. These findings indicate the importance of steroid hormones, prostaglandins and myometrial gap junctions in the control of myometrial contractility during pregnancy and labor. Our study in pregnant ewes shows the relationship between the presence of gap junctions during labor and the observed increase in myometrial contractility. Gap function formation, Which facilitates the spread of electrical activity across the myometrium, appears to be associated with enhanced coordination of contractile activity of the myometrial smooth muscle cells. The increase in the number of gap junctions which occurs in all species investigated, also in humans, seems to be a necessary step in the initiation of parturition. The results of our study, as well as those of studies by others in sheep, rats and rabbits, indicate that gap junction formation is regulated and modulated by steroid hormones. Progesterone inhibits and estradiol stimulates the formation of gap junctions. Since investigation in vivo of the regulation of gap junction formation by steroid hormones, and by other factors such as prostaglandin synthesis, causes considerable difficulties in pregnant animals, we developed a nonpregnant animal model in which several factors could be manipulated more easil

Developing the logic framework underpinning a whole-systems approach to childhood overweight and obesity prevention:Amsterdam Healthy Weight Approach

Abstract Background Whole‐systems approaches (WSAs) are well placed to tackle the complex local environmental influences on overweight and obesity, yet there are few examples of WSAs in practice. Amsterdam Healthy Weight Approach (AHWA) is a long‐term, municipality‐led program to improve children's physical activity, diet, and sleep through action in the home, neighborhood, school, and city. Adopting a WSA, local political, physical, social, educational, and healthcare drivers of childhood obesity are viewed as a complex adaptive system. Since 2013, AHWA has reached >15,000 children. During this time, the estimated prevalence of 2–18‐year‐olds with overweight or obesity in Amsterdam has declined from 21% in 2012 to 18.7% in 2017. Declining trends are rarely observed in cities. There is a need to formally articulate AHWA program theory in order to: (i) inform future program evaluation which can interpret this decline within the context of AHWA and (ii) contribute a real‐life example of a WSA to the literature. Methods This study aimed to formally document the program theory of AHWA to permit future evaluation. A logic framework was developed through extensive document review and discussion, during program implementation. Results The working principles of the WSA underpinning AHWA were made explicit in an overarching theory of change, articulated in a logic framework. The framework was operationalized using an illustrative example of sugar intake. Conclusions The logic framework will inform AHWA development, monitoring, and evaluation and responds to a wider need to outline the working principles of WSAs in public health

Decrease of free thyroxine levels after controlled ovarian hyperstimulation

Controlled ovarian hyperstimulation could lead to opposing effects on thyroid function. Therefore, in a prospective study of 65 women undergoing controlled ovarian hyperstimulation, thyroid hormones, T4-binding globulin, TPO antibodies, gonadotropins, estradiol, and PRL were measured before and after controlled ovarian hyperstimulation. After ovarian stimulation (mean +/- SE of mean): free T4 decreased, 14.4 +/- 0.2 vs. 12.9 +/- 0.2 pmol/L (P < 0.0001); thyroid-stimulating hormone increased, 2.3 +/- 0.3 vs. 3.0 +/- 0.4 mU/L (P < 0.0001); T4-binding globulin increased, 25.2 +/- 0.7 vs. 33.9 +/- 0.9 mg/L (P < 0.0001); total T4 increased, 98.1 +/- 2.3 vs. 114.6 +/- 2.5 nmol/L (P < 0.0001); total T3 increased, 2.0 +/- 0.04 vs. 2.3 +/- 0.07 nmol/L (P < 0.0001); TPO antibodies decreased, 370 +/- 233 U/mL vs. 355 +/- 224 U/mL (P < 0.0001); LH decreased, 8.1 +/- 1.1 vs. 0.4 +/-0.1 U/L (P < 0.0001); FSH did not change, 6.5 +/- 0.6 vs. 7.9 +/- 0.9 U/L (P = 0.08); human CG increased, <2 +/- 0.0 vs. 195 +/- 16 U/L (P < 0.0001); estradiol increased, 359.3 +/- 25.9 pmol/L vs. 3491.8 +/-298.3 pmol/L (P < 0.0001); and PRL increased, 0.23 +/- 0.02 vs. 0.95 +/- 0.06 U/L (P < 0.0001). Because low maternal free T4 and elevated maternal thyroid-stimulating hormone levels during early gestation have been reported to be associated with impaired psychomotor development in the offspring, our findings indicate the need for additional studies in the children of women who where exposed to high levels of estrogens around the time of conception

Improving Physical Activity Levels in Prevocational Students by Student Participation:Protocol for a Cluster Randomized Controlled Trial

BACKGROUND: A consistent finding in the literature is the decline in physical activity during adolescence, resulting in activity levels below the recommended guidelines. Therefore, promotion of physical activity is recommended specifically for prevocational students. OBJECTIVE: This protocol paper describes the background and design of a physical activity promotion intervention study in which prevocational students are invited to participate in the design and implementation of an intervention mix. The intervention is expected to prevent a decline in physical activity in the target group. METHODS: The effectiveness of the intervention was evaluated in a two-group cluster randomized controlled trial with assessments at baseline and 2-year follow-up. A simple randomization was applied, allocating 11 schools to the intervention group and 11 schools to the control group, which followed the regular school curriculum. The research population consisted of 3003 prevocational students, aged 13-15 years. The primary outcome measures were self-reported physical activity levels (screen time, active commuting, and physical activity). As a secondary outcome, direct assessment of physical fitness (leg strength, arm strength, hip flexibility, hand speed, abdominal muscle strength, BMI, and body composition) was included. An intervention-control group comparison was presented for the baseline results. The 2-year interventions began by mapping the assets of the prevocational adolescents of each intervention school using motivational interviewing in the structured interview matrix and the photovoice method. In addition, during focus group sessions, students, school employees, and researchers cocreated and implemented an intervention plan that optimally met the students’ assets and opportunities in the school context. The degree of student participation was evaluated through interviews and questionnaires. RESULTS: Data collection of the SALVO (stimulating an active lifestyle in prevocational students) study began in October 2015 and was completed in December 2017. Data analyses will be completed in 2021. Baseline comparisons between the intervention and control groups were not significant for age (P=.12), screen time behavior (P=.53), nonschool active commuting (P=.26), total time spent on sports activities (P=.32), total physical activities (P=.11), hip flexibility (P=.22), maximum handgrip (P=.47), BMI (P=.44), and sum of skinfolds (P=.29). Significant differences between the intervention and control groups were found in ethnicity, gender, active commuting to school (P=.03), standing broad jump (P=.02), bent arm hang (P=.01), 10× 5-m sprint (P=.01), plate tapping (P=.01), sit-ups (P=.01), and 20-m shuttle run (P=.01). CONCLUSIONS: The SALVO study assesses the effects of a participatory intervention on physical activity and fitness levels in prevocational students. The results of this study may lead to a new understanding of the effectiveness of school-based physical activity interventions when students are invited to participate and cocreate an intervention. This process would provide structured health promotion for future public health. TRIAL REGISTRATION: ISRCTN Registry ISRCTN35992636; http://www.isrctn.com/ISRCTN35992636 INTERNATIONAL REGISTERED REPORT IDENTIFIER (IRRID): DERR1-10.2196/2827