OBJECTIVE: Periodontitis, mostly associated with Porphyromonas gingivalis, has frequently been related to adverse pregnancy outcomes. We therefore investigated whether lipopolysaccharides of P. gingivalis (Pg-LPS) induced pregnancy complications in the rat.METHODS: Experiment 1: pregnant rats (day 14) received increasing Pg-LPS doses (0.0-50.0 μg kg-1 bw; n = 2/3 p per dose). Maternal intra-aortic blood pressure, urinary albumin excretion, placental and foetal weight and foetal resorptions were documented. Experiment 2: 10.0 μg kg-1 bw (which induced the highest blood pressure together with decreased foetal weight in experiment 1) or saline was infused in pregnant and non-pregnant rats (n = 7/9 p per group). Parameters of experiment 1 and numbers of peripheral leucocytes as well as signs of inflammation in the kidney and placenta were evaluated.RESULTS: Pg-LPS infusion in pregnant rats increased maternal systolic blood pressure, reduced placental weight (dose dependently) and decreased foetal weight and induced foetal resorptions. It, however, did not induce proteinuria or a generalised inflammatory response. No effects of Pg-LPS were seen in non-pregnant rats.CONCLUSION: Pg-LPS increased maternal blood pressure, induced placental and foetal growth restriction, and increased foetal resorptions, without inducing proteinuria and inflammation. Pg-LPS may therefore play a role in pregnancy complications induced by periodontitis.
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Er lijkt een duidelijke mate van evidentie te bestaan betreffende de relatie fysieke activiteit, respectievelijk fitheid en gezondheid in de algemene populatie en bij bepaalde pathologieën. Er is evenwel nog behoefte aan verder wetenschappelijk onderzoek naar mogelijke determinanten en onderliggende mechanismen, als ook naar evidentie bij bepaalde, specifieke aandoeningen. Tevens mag duidelijk zijn dat ondanks de bestaande evidentie fysieke activiteit/oefening te weinig toegepast wordt in de gezondheidszorg. Het onderzoek naar de effectiviteit van gezondheidskundige interventies is dan ook uitermate belangrijk. Dit lectoraat hoopt dan ook een bescheiden bijdrage hieraan te kunnen leveren. Hiervoor heeft zij reeds afspraken tot samenwerking met de academische en medische wereld (in Utrecht, Amsterdam, Maastricht en Leuven), met de gezondheidszorg (RIVM Bilthoven en GG&GD Utrecht) en met de beroepen- of bedrijfswereld (Politie regio Utrecht; Enraf Nonius, Delft). De beoogde doelstellingen zullen echter naar alle waarschijnlijkheid beduidend meer tijd in beslag nemen dan de periode van 4 jaar die de Stichting Kennis Ontwikkeling voorzien heeft met betrekking tot het oprichten en financieren van de lectoraten.
Regular physical activity is considered to be an important component of a healthy lifestyle that decreases the risk of coronary heart disease, diabetes mellitus type 2, hypertension, colon and breast cancer, obesity and other debilitating conditions. Physical activity can also improve functional capacity and therefore also the quality of life in older adults. Despite all these favorable aspects, a substantial part of the Dutch older adult population is still underactive or even sedentary. To change this for the better, the Groningen Active Living Model (GALM) was developed.Aim of GALM is to stimulate recreational sports activities in sedentary and underactive older adults in the 55-65 age band. After a door-to-door visit as part of an intensive recruitment phase, a fitness test was conducted followed by the GALM recreational sports program. This program was based on principles from evolutionary-biological play theory and insights fromsocial cognitive theory. The program was versatile in nature (e.g. softball, dance, self-defense, swimming, athletics, etc.) in two main ways: a) to improve compliance with the program different sports were offered, which was reported to be more appealing for older adults; b) by aiming at more components of motor fitness (e.g. strength, flexibility, speed, endurance and coordination). Between 1997 and 2005 more than 552,000 persons were visited door-to-door, over 55,700 were tested, and 41,310 participated in the GALM recreational sports program. The aim of the present thesis is to determine the effects of participation in the GALM recreational sports program on physical activity, health and fitness outcomes.Chapter 2 describes the effectiveness of the GALM recruitment in selecting and recruiting sedentary and underactive older adults. Three municipalities in the Netherlands were selected, and in every municipality four neighborhoods were included. Two of each of the four neighborhoods were randomly assigned as intervention and the others as control neighborhoods. In total, 8,504 persons were mailed and received a home visit. During this home visit the GALM recruitment questionnaire was collected on which the selection between sedentary/underactive and physically active older adults was based. Ultimately we succeeded inincluding 12.3% (315 of the 2,551 qualifying) of the older adults, 79.4% of whom could be indeed considered sedentary or underactive. The cost of successfully recruiting an older adult was estimated at $84.To assess the effects of a physical activity intervention on health and fitness and explain the results, it is necessary to know program characteristics regarding frequency, intensity, time and content of the activities. With respect to the GALM recreational sports activity program, the only unknown characteristic was intensity. Chapter 3 describes the intensity of this program systematically. Using heart rate monitors, data of 97 persons (mean age 60.1 yr) were collected in three municipalities. The mean intensity of all 15 GALM sessions was 73.7% of the predicted maximal heart rate. Six percent of the monitored heart rate time could be classified as light, 33% as moderate and 61% as hard. In summary, the GALM recreational sports program meets the 1998 ACSM recommendations for intensity necessary to improve cardiorespiratory fitness.Chapters 4 and 5 describe the effects of 6 and 12 months of participation in the GALM recreational sports program, and 181 persons were followed over time. Results after 6 months revealed only few significant between-group differences favoring the intervention group (i.e. sleep, diastolic blood pressure, perceived fitness score and grip strength). Changes in energyexpenditure for leisure-time physical activities (EELTPA) showed an increase in both study groups. From 6 to 12 months a decrease in EELTPA occurred in the intervention group and an increase in the control group. The significant positive time effects for the health outcomes (diastolic blood pressure, BMI, percentage of body fat) that were found after 6 months were diminishedfrom 6 to 12 months. However, the energy expenditure for recreational sports activities (EERECSPORT) demonstrated a continuous increase over 12 months. Parallel to this, significant main effects for time were found in performance-based fitness outcomes (i.e. simple reaction time, leg strength, flexibility of hamstrings and lower back, and aerobic endurance). After 12 months only a significant between-group difference for flexibility of the hamstrings andlower back was found, favoring the control group. In conclusion, a short-term increase in EELTPA was found with accompanying improvements in health outcomes that more or less disappeared in 6 to 12 months. In the long term, results showed a continuous increase in EERECSPORT and performance-based fitness. This latter increase is probably a reflection of the significantimprovement over time in EERECSPORT and the fact that recreational sports activities are of a higher intensity.Aerobic endurance is regarded as the most important component of motor fitness that is relevant for older adults to function independently. In Chapter 6, the development in aerobic endurance after 18 months of participation in the GALM recreational sports program was assessed by means of changes in heart rate during fixed submaximal exercise. Since both groups were comparable regarding changes in energy expenditure for physical activity after 6 months and testing confirmed this, both groups were combined and considered as one group. Multilevel analyses were conducted and models for change were developed. A significant decrease in heart rate over time was found at all walking speeds (4, 5, 6 and 7 km/h). The average decrease in heart rate was 5.5, 6.0, 10.0 and 9.0 beats/min for the 4, 5, 6 and 7 km/h walking speeds, respectively. The relative decrease varied from 5.1 to 7.4% relative to average heart rates at baseline. These results illustrate that participation in the GALM recreational sports program has a positive significant effect on aerobic endurance, and that the participants are able to perform at submaximal intensity more easily.Based on the overall results it can be concluded that this study contributes to the field in how to effectively recruit sedentary and underactive older adults and stimulate them to become and stay active in recreational sports activities. As far as we know, this recruitment in combination with the recreational sport program is not only unique but also effective toward increasing performance-based fitness in the long term. Short-term effects were found in other leisure-time activities and health outcomes. To further stimulate other leisure-time and probably health outcomes besides the favorable effects that were already seen, additional interventions that pay more attention to behavioral change in terms of how to integrate other activities besides sports activities are recommended.
