Inledning: Prevalensen av karies och övervikt/fetma hos barn och ungdomar beskrivs kort. Syfte: Att kartlägga och analysera studier som undersökt sambandet mellan kariesprevalens och BMI hos barn och ungdomar. Följande frågeställningar ska besvaras: Finns det en korrelation mellan kariesprevalens och BMI? Har gruppen överviktiga barn och ungdomar högre kariesprevalens? Har gruppen underviktiga barn och ungdomar högre kariesprevalens? Metod: Frågeställningarna besvaras med hjälp av en systematisk litteraturöversikt. Resultat: Utav sammanställningens 28 artiklar visade 14 på samband mellan karies och BMI och lika många visade inget samband. Tre av de som påvisade samband gjorde detta mellan karies och undervikt.Slutsats: Samband mellan kariesprevalens och BMI har visats i flera studier, medan andra studier inte har kunnat visa detta. Ytterligare studier behövs för att tydligare identifiera vilka faktorer som eventuellt är gemensamma och viktiga för utveckling av både karies och undervikt/övervikt/fetma hos barn och ungdomar. / Introduction: The prevalence of dental caries and underweight/overweight/obesity in children and adolescents are described briefly.Objective: To survey and analyze studies that examined the relationship between caries prevalence and BMI in children and adolescents. The following questions were to be answered: Is there a correlation between caries prevalence and BMI? Does the group of overweight children and adolescents have a higher caries prevalence? Does the group of underweight children and adolescents have a higher caries prevalence?Method: These questions were to be answered by a systematic literature review. Results: In the collection of all articles, it was fourteen that showed a correlation between dental caries and BMI and an equal number who did not show correlation. Of those who indicate a connection, there were three studies that showed a correlation between dental caries and underweight.Conclusion: Correlation between caries prevalence and BMI has been shown in several studies, other studies have not been able to show any correlation. Further studies are needed in the future to more clearly identify the factors that may be common and important for the development of both dental caries and underweight / overweight / obesity in children and adolescents.

Résumé : Problématique: Les comportements alimentaires à la petite enfance pourraient influencer le gain de poids. Alors que les enfants d’âge préscolaire passent beaucoup de temps dans des milieux de garde, peu d’études ne rapportent les liens entre leurs comportements alimentaires dans ces milieux et leur composition corporelle. De plus, les recherches dans ce domaine sont basées sur des données subjectives des parents. Les objectifs étaient donc de développer un outil de mesure objectif des comportements alimentaires et de l’utiliser afin d’examiner le lien entre ceux-ci en milieu de garde et la composition corporelle des enfants d’âge préscolaire. Méthodes : Cette étude transversale a été menée auprès de 309 enfants de 3 à 5 ans dans 24 milieux de garde. Le comportement alimentaire a été mesuré en effectuant l’évaluation des restes au repas du dîner. Les données de ces évaluations ont été utilisées pour développer un score représentant la réticence alimentaire et un représentant l’affinité. Des corrélations intra-classes ont été utilisées afin de déterminer la fidélité des nouvelles mesures. Des corrélations de Spearman ont été utilisées afin de comparer les nouvelles mesures aux comportements alimentaires rapportés par les parents. Des régressions linéaires multivariées ont été utilisées pour examiner la relation entre les scores de comportement alimentaire mesurées objectivement et le tour de taille et l’indice de masse corporelle (IMC) ajusté à l’âge des enfants. Résultats : La nouvelle mesure de réticence alimentaire a démontré une excellente fidélité inter-juge (ICC= 0,970 à 0,998, p<0.0001), intra-juge (ICC=0,975 à 0,998, p<0.0001) et une bonne fidélité test-retest (ICC=0,723, p<0.0001). Elle corrélait également avec une mesure subjective précédemment validée (rho= 0,534, p<0.0001). La nouvelle mesure d’affinité alimentaire n’était toutefois pas valide (rho= -0,182, p=0,2). Le score de réticence alimentaire était positivement associé à l’IMC ajusté à l’âge des enfants (bêta ajusté= 1,41, IC à 95%=0,15, 2,67), mais non avec leur tour de taille (bêta ajusté=0,60, IC à 95%= -0,86, 2,06). Conclusion : La nouvelle mesure de réticence alimentaire démontre une excellente fidélité et validité chez les enfants d’âge préscolaire en milieu de garde. Plus il y avait de la réticence alimentaire, plus l’IMC ajusté à l’âge abaisse. Les milieux de gardes pourraient donc être des milieux propices pour l’implantation d’interventions pour réduire la réticence alimentaire, et contrer l’insuffisance pondérale chez les jeunes affectés. / Abstract : Background: Eating behaviours could be associated with weight gain during early childhood. Although a majority of preschoolers spend most of their active day-time hours in daycare centres, associations between their eating behaviours at daycare and their body composition have been limitedly studied. Further, research on eating behaviours of children mainly relies on parent-reported measures. The objective of this study was to develop an objective measure of eating behaviours and to use it to assess the relationship between these behaviours and body mass index and waist circumference among preschoolers. Methods: This cross-sectional study was conducted among 309 children aged 3 to 5 in 24 daycare centres. Eating behaviours were measured through weighted digital plate waste analysis. Data from this evaluation was used to create a food reluctance score and a food affinity score. Intraclass correlations (ICC) were used to determine the reliability of the new measure. Spearman correlations were used to compare the new measures with parental report of eating behaviours. Multivariate linear regressions were used to examine the relationship between objectively measured food behaviours and children’s waist circumference and age-adjusted body mass index (BMI). Results: The new measure of food reluctance demonstrated excellent inter-rater reliability (ICC= 0.970 to 0.998, p<0.0001), intra-rater reliability (ICC=0.975 to 0.998, p<0.0001), and good test-retest reliability (ICC=0.723, p<0.0001). It also provided evidence of concurrent validity through correlation with a validated subjective measure (rho= 0.534, p<0.0001). The new measure of food affinity was however not valid (rho= -0.182, p=0.2). The food reluctance score was positively associated with children’s age-adjusted BMI (adjusted bêta; 95% CI= 1.41, 0.15, 2.67), but not with their waist circumference (0.60; -0.86, 2.06). Conclusion: The objective measure of food reluctance demonstrated evidence of reliability and validity. Greater demonstration of food reluctance at the daycare center was associated with a lower BMI. This suggests that daycare centers could represent promising settings for integrating strategies to counter food reluctance and counter inadequate weight gain among affected preschoolers.

Der Ernährungsstatus ist ein wichtiger Einflussfaktor auf den Gesundheitszustand von Kindern und Jugendlichen. Sowohl Unter- als auch Übergewicht können den Krankheitsverlauf beeinflussen und stellen einen Risikofaktor für die Entwicklung weiterer Erkrankungen dar. Über die Prävalenz von Über- und Untergewicht bei hospitalisierten Kindern und Jugendlichen in Deutschland ist wenig bekannt. In der vorliegenden Arbeit werden die Daten von 906 Patienten zwischen 0 und 17 Jahren, die auf eine allgemein-pädiatrische Station mit neuropädiatrischem Schwerpunkt der Universitätsmedizin Göttingen im Jahr 2012 aufgenommen wurden, erhoben. Die Prävalenz und der Zusammenhang zwischen Über- und Untergewicht, eingeteilt nach BMI-Perzentilen und sozialen Faktoren, individuellen Faktoren und Erkrankung wurden untersucht und mit einem gesunden Referenzkollektiv aus der KiGGS-Studie des Robert Koch-Instituts verglichen. Von den 906 Patienten sind 458 männlich und 448 weiblich. 15,45% der Patienten sind mit einem BMI unter der 10. Perzentile untergewichtig, davon ist etwa die Hälfte (8,72%) mit einem BMI unter der 3. Perzentile stark untergewichtig. Übergewichtig (BMI >90. Perzentile) sind 16,56% der Kinder und Jugendlichen, davon 6,91% mit einem BMI über der 97. Perzentile adipös. Die am häufigsten von Untergewicht betroffene Altersgruppe ist die von 0-2 Jahren (25,34%, OR: 2,29-3,65), Übergewicht und Adipositas treten am häufigsten in der Altersgruppe zwischen 14 und 17 Jahren auf (21,15%). Kinder mit niedrigem Geburtsgewicht und Frühgeborene sind auch später häufiger untergewichtig (32,79%, p=0,013 und 22,7%, p=0,082). Mentale Retardierung und schwere körperliche Beeinträchtigung sind signifikant häufiger mit Untergewicht assoziiert (OR=2,1 und OR=3,6) ebenso wie infektiöse und parasitäre Erkrankungen (OR=6,27), Entwicklungsstörungen allgemein (OR=5,4), zerebrale Lähmungen und sonstige Lähmungssyndrome (OR=5,26) und Verletzungen des Kopfes (OR=2,59). Dagegen sind Kinder und Jugendliche mit Multipler Sklerose häufiger von Übergewicht betroffen (OR=2,14). Erkrankungsgruppen mit vermehrtem Vorkommen von sowohl Unter- als auch Übergewicht sind Neubildungen (OR=5,12 und OR=3,32) und angeborene Fehlbildungen, Deformitäten und Chromosomenanomalien (OR=3,76 und OR=1,49). Im Gesamtvergleich zwischen hospitalisierten Kindern und Jugendlichen und der gesunden Referenzgruppen zeigt sich kein signifikanter Unterschied in der Prävalenz von Unter- und Übergewicht. Einzelne Erkrankungsgruppen sind jedoch besonders häufig mit Unter- oder Übergewicht assoziiert. Um eine optimale Versorgung dieser betroffenen Kinder und Jugendlichen sicherzustellen, muss die Identifikation und Betreuung von akut und chronisch kranken Kindern und Jugendlichen mit Ernährungsstörungen verbessert und zu einem integralen Bestandteil im klinischen Alltag werden.

No description available.

PhD, Faculty of Health Sciences, University of the Witwatersrand / Background: In low- to middle-income countries, rising levels of overweight and obesity are a result of multiple transitions, in particular, a nutrition transition. Consequently, in these countries, metabolic diseases are contributing increasingly to disease burden, despite the persisting burden of undernutrition and infectious diseases. Understanding the patterns and factors associated with persistent undernutrition and emerging obesity in children and adolescents, and concomitant risk for metabolic disease, is therefore of criticial importance. This should contribute to public health policy on interventions to prevent adult disease. Aims: To better understand the double burden of malnutrition in a poor, high HIV prevalent, transitional society in a middle-income country; In so doing, to inform policies and interventions to address the double burden of malnutrition. Methods: A cross-sectional growth survey was conducted in 2007 targeting 4000 children and adolescents 1-20 years of age living in rural South Africa. The survey was nested within the ongoing Agincourt Health and Socio-demographic Surveillance System, which acted as the sampling frame and also provided data for explanatory variables. Anthropometric measurements were performed on all participants using standard procedures. In addition, HIV testing was done on children aged 1 to 5 years and Tanner pubertal assessment was conducted among adolescents 9-20 years. A one-year follow-up of HIV positive children included a matched control group of HIV negative counterparts. Data collection involved both quantitative and qualitative methods. Growth z-scores were used to determine stunting, underweight and wasting and were generated using the 2006 WHO growth standards for children up to five years and the 1977 NCHS/WHO reference for older children. Overweight and obesity were determined using the International Obesity Task Force cut-offs for BMI for children aged up to 17 years and adult cut offs of BMI =25 and =30 kg/m2 for overweight and obesity respectively for adolescents 18 to 20 years. Waist circumference cut-offs of =94cm for males and =80cm for females, and waist-to-height ratio of 0.5 for both sexes, were used to determine central obesity and hence metabolic disease risk in ix adolescents. Descriptive analysis described patterns of nutritional status by age, sex, pubertal stage and HIV status. Linear and logistic regression was done to determine predictors of nutrional outcomes. A p-value of <0.05 was considered statistically significant. Results: Prevalence of undernutrition, particularly stunting, was substantial: 18% among children aged 1-4 years, with a peak of 32% in children at one year of age. Stunting and underweight were also substantial in adolescent boys, with underweight reaching a peak of 19% at 14 years of age. Concurrently, the prevalence of combined overweight and obesity, almost non-existent in boys, was prominent among adolescent girls, increasing with age, and reaching a peak of 25% at 18 years. Risk for metabolic disease using waist circumference cut-offs was substantial among adolescents, particularly girls, increasing with sexual maturation, and reaching a peak of 35% at Tanner stage 5. Prevalence of HIV in children aged 1-4 years was 4.4%. HIV positive children had poorer nutritional outcomes than that of HIV negative children in 2007. The impact of paediatric HIV on nutritional status at community level was, however, not significant. Significant predictors of undernutrition in children aged 1-4 years, documented at child, maternal, household and community levels, included child’s HIV status, age and birth weight; maternal age; age of household head; and area of residence. Significant predictors of overweight/obesity and risk for metabolic disease in adolescents aged 10-20 years, documented at individual/child and household levels included child’s age, sex and pubertal development; and household-level food security, socio-economic status, and household head’s highest education level. There was a high acceptance rate for the HIV test (95%). One year following the test, almost all caregivers had accepted and valued knowing their child’s HIV status, indicating that it enhanced their competency in caregiving. Additionally, nutritional status of HIV positive children had improved significantly within a year of follow-up. Conclusions: The study describes co-existing child stunting and adolescent overweight/obesity and risk for metabolic disease in a society undergoing nutrition transition. While likely that this profile reflects changes in nutrition and diet, variation in infectious disease burden, physical activity patterns, and social influences need to be investigated. The findings are critical in the wake of the rising public health importance of metabolic diseases in low- to middle-income countries, despite the unfinished agenda of undernutrition and infectious diseases. Clearly, policies and interventions to address malnutrition in this and other transitional societies need to be double-pronged. In addition, gender-biased nutritional patterns call for gender-sensitive policies and interventions. The study further documents a significant role of paediatric HIV on nutritional status, and the potential for community-based paediatic HIV testing to ameliorate this. Targeted early paediatric HIV testing of exposed or at risk children, followed by appropriate health care for infected children, may improve their nutritional status and survival.

Esse trabalho é dedicado ao desenvolvimento de um simulador para sistema de pesagem e embalagem de produto em pó granulado. Tal simulador reproduz a variabilidade de peso dos cartuchos observados em um sistema de embalagem real. Para esse desenvolvimento foram aplicadas técnicas de Identificação de Sistemas para obter o modelo determinístico do processo e conceitos de Processos Estocásticos para reproduzir as perturbações. O simulador tem como objetivo a avaliação de propostas de melhorias nesse sistema de pesagem, visando reduzir o sobrepeso médio e a quantidade de cartuchos rejeitados por subpeso, denominados de scraps, diminuindo consequentemente as perdas monetárias do processo industrial de embalagem de produtos granulados, com grande potencial de reaplicação para outros tipos de produtos industrializados e sistemas de pesagem. O desempenho do simulador é muito bom, uma vez que as oscilações observadas nos pesos dos cartuchos, devido à variação de densidade, são bem reproduzidas. Portanto as principais contribuições desse trabalho são: 1) o uso de uma abordagem estatística e inovadora para modelar as perturbações, evitando o estudo profundo de suas causas, alcançando um modelo preciso, que simula resultados de sobrepeso e número de cartuchos rejeitados bem próximo da realidade; 2) identificação e quantificação de melhorias no sistema de pesagem e embalagem, sem a necessidade de altos investimentos, dando a opção de decisão de quais melhorias realmente serão implementadas; 3) sobrepeso e scrap normalmente estão entre as três principais perdas monetárias das indústrias que produzem produtos embalados por peso e esse simulador representa uma forma de redução significativa dessas perdas, trazendo uma grande vantagem competitiva em um mercado cada vez mais acirrado. / This work describes the development of a simulator for a packing and weighing system of granulated powder. This simulator reproduces the weight variability of observed cartons in a real packing system. In this development, System Identification techniques were used to obtain the deterministic part of the model and Stochastic Processes to reproduce disturbances. Its objective is to evaluate proposed improvements in the packing and weighing system, aiming at reducing the overweight average and the quantity of rejected cartons by underweight, denominated scraps, cutting down consequently the monetary losses of the granulated product packing process in the industry, with great reapplication potential to other kind of industry products and weighing systems. The simulator performance is very satisfactory, once the oscillations observed in the carton weights, due to powder density variability, are well reproduced. Hence, the main contributions of this work are: 1) use of a statistical and innovative approach to model the disturbances, avoiding a deep study of their causes, achieving a model that provided precise simulated overpacking and scrap results when compared to reality; 2) identification and quantification improvements of the weighing and packing system, with no large investment, giving the option of decision of which improvement will be actually implemented; 3) overweight and scrap are among the three main monetary losses in the industries that make products packed in weight and so this simulator of a packing and weighing system of granulated powder represents a way of reducing significantly these losses, bringing a big competitive advantage in a demanding market.

Objetivos: Analisar o ajuste alométrico para MC e altura entre indivíduos menores de 20 anos. Métodos: Dados de indivíduos de 0-20 anos de National Health and Nutrition Examination Survey (NHANES-1999-2013); Pesquisa Nacional de Saúde e Nutrição (PNSN-1989); Encuesta de Salud y Nutrición (2012); England Health Survei (2005-2014) e; Korean National Health and Nutrition Examination Survey (KNHANES-1998-2014). MC e de altura foram convertidos à escala logarítmica e modelados por regressão linear em 24 grupos etários, 2 sexos e os 5 países. O &#946; dessa regressão deu origem ao p valor que foi estimado em 2 etapas. 1) Todos os dados disponíveis nos inquéritos, excluíndo apenas os valores biologicamente implausíveis; e 2) O p foi calculado após a exclusão dos valores não esperados para idade (VNEI) de MC e altura. VNEI foi definido como casos ±2,0 DP(z) do resíduo da regressão de MC pela idade, altura pela idade e MC pela altura. Em seguida, os valores p definidos no pool de dados foram modelados por spline com 5 knots, para definição de um p internacional (ip). Após calculou-se o IA - Indice Alométrico para todos os individuos. Para análise da correlação entre os índices e a massa adiposa foram utilizadas medidas de Densiotometria (DXA), Impedância Bioelétrica (BIA), Circunferência de Cintura (CC) e Dobras Cutâneas (DC). As correlações com os indices foram estimada pelo coeficiente de Pearson(r). Em uma análise de efeitos mistos, estimou-se o coeficiente correlção intraclasses (CCI), entre os diferentes países e as diferentes fenótipos humanos para altura, MC, IMC e IA. Resultados: A exclusão de VNEI (8,5% da amostra) diminuiu a diferença do p entre os países. O p e o ip apresentoram valores próximos a 2 ao nascimento, aumentou para 3 a 3,5 (7 e 11 anos nas meninas e 8 a 12 nos meninos) e regrediu a 2 no final do crescimento. O IA apresentou r próximo de zero em relação a altura contra r proximos de 0,4 para o IMC durante a puberdade. A correlação da massa adiposa para os dois indices foi semelhante, sempre apresentando r acima de 0,85 para todas as formas de análise via DC, BIA, CC e DXA. IA apresentou menor correlação com massa muscular e densidade óssea. O CCI foi maior entre os paises e praticamente nulo entre as fenótipos humanos. A maior variação entre os paises ficou a cargo da altura, seguido da massa corporal e IMC. O IA foi a medida que se apresentou com menor variação entre os paises (3,6%) e entre fenótipos humanos (1,7%). Conclusões: A exclusão VNEI contribuiu para diminuir o efeito do estado nutricional sobre a alometria para se estimar o p valor. O ip mostrou-se uma valor promissor para uso internacional. O IA no conjunto de evidências apresenta uma vantagem em relação ao IMC, uma vez que tem correlção 0 com a altura, e uma correlação equivalente ao IMC com a massa adiposa além de apresentar o menor CCI entre fenótipos humanos e nacionalidades. A maior variação do CCI ficou a cargo do país em relação a altura, justificado pelos difentes contextos epidemiológicos. / Objectives: To analyze the allometric scalling for BM and the height under 20 years old. Methods: Individuals 0-20 years of the National Health and Nutrition Examination Survey (NHANES-1999-2013); Pesquisa Nacional de Saúde e Nutrição (PNSN-1989); Encuesta de Salud y Nutrición (2012); England Health Survei (2005-2014) and; Korean National Health and Nutrition Examination Survey (KNHANES-1998-2014). BM and height were converted to logarithmic scale and modeled by linear regression, in 24 age groups, 2 sexes and 5 countries. The &#946; of this regression gave the estimated p value in 2 steps. 1) All data available in the surveys, excluding only those biologically implausible values; and 2) The value was obtained after the exclusion of values not expected for age (VNEA) of MC and height. VNEA was defined as ± 2.0 SD (z) cases of regression of BM by age, height by age and MC by height. Then, the values were modeled by spline in 5 knots, to define an international (ip). After were calculated the AI - Allometric Index for all individuals. The Pearson correlation (r) between the indices and the fat mass was calculated used data dorm densitometry (DXA), Bioelectrical Impedance (BIA), Waist Circumference (WC) and Skin Folds (SF). In an analysis of mixed effects, was estimated the intraclass correlation coefficient (ICC), between countries and ethnicities for different dimensions for BM, BMI and AI. Results: Exclusion of VNEA (8.5% of the sample) decreased the difference between countries. The p and ip presented values close to 2 at birth, increased to 3 to 3.5 (7 and 11 years in girls and 8 to 12 in boys) and recorded 2 at the end of growth. AI was close to zero in correlation with height and for BMI was r= 0.4 during puberty. The correlation of the adipose mass for the two indices was similar, always presenting r above 0.85 for all forms of analysis via DC, BIA, CC and DXA. AI presented a lower correlation with muscle mass and bone density. ICC is larger among countries and is practically zero among ethnicities. The greatest difference between the groups was the height, the BM and the BMI. AI showed the smallest difference between the countries (3.6%) and between the ethnic groups (1.7%). Conclusions: A VNEA exclusion contributed to decrease the effect of nutritional status on allometry to estimate the p value. The value ip has proved to be a promising value for international use. The IA in the body of evidence has an advantage over BMI, since it has correlation 0 with height, and a correlation equivalent to the BMI with the adipose mass besides presenting the lowest CCI between ethnicities and nationalities. The greatest variation of ICC was borne by the country in relation to height, justified by the different epidemiological contexts.

Le but de ce travail était de déterminer les effets de la pratique d'activité physique sur le phénotype osseux et l'adiposité médullaire en cas d'insuffisance pondérale selon deux approches complémentaires, chez l'humain et chez les souris. La première étude a été menée sur 24 femmes normo-pondérées et 13 femmes en sous-poids âgées entre 20 et 35 ans. Cette étude a montré que les femmes en sous-poids présentent une faible masse osseuse au niveau du corps entier, rachis lombaire et col fémoral et une altération de la géométrie du col fémoral par rapport aux femmes normo-pondérées, et un score de l'os trabéculaire sur la limite inférieure de la normale. La VO₂ₘₐₓ (L/min) était parmi les principaux déterminants des paramètres osseux chez les jeunes femmes quel que soit leur indice de masse corporelle. Les résultats de cette première étude suggèrent que l'augmentation de la VO₂ₘₐₓ (L/min) sont essentiels pour prévenir la perte osseuse chez les jeunes femmes en sous-poids. La deuxième étude a été menée sur des souris femelles jeunes adultes soumises à un exercice physique volontaire dans une roue combinée à une restriction alimentaire (restriction de 50% de l'apport ad libitum) pendant 15 et 55 jours. Cette étude a démontré que la perte pondérale liée à la restriction alimentaire présente des répercussions négatives sur l'os cortical avec peu d'effets néfastes sur l'os trabéculaire et est associée à une augmentation du nombre des adipocytes médullaires dès 15 jours de restriction. Cette étude a également démontré que l'exercice physique volontaire dans une roue ne protège pas contre les modifications de l'architecture osseuse et l'accumulation de l'adiposité médullaire liées à la restriction alimentaire. Parce que la ghréline est apparue comme régulateur potentiel de l'adiposité médullaire, la troisième étude a été menée sur des souris femelles jeunes adultes dépourvues du récepteur de la ghréline (Growth Hormone Secretagogue Receptor, Ghsr-/-) soumises à une restriction alimentaire (restriction de 50% de l'apport ad libitum) combinée à un exercice physique volontaire dans une roue de 21 jours. Cette étude a démontré que la ghréline est un médiateur clé de l'expansion de l'adiposité médullaire associée à la restriction alimentaire suite à l'activation du GHSR et que la restriction alimentaire est nécessaire pour révéler certaines différences dans la microarchitecture osseuse associée à l'invalidation du GHSR. / The aim of this work was to determine the effects of physical activity on bone phenotype and bone marrow adiposity in underweight conditions using two complementary approaches, on human and on mice. The first study was conducted on 24 normal weight women and 13 underweight women aged 20-35 years. This study showed that underweight women have appropriately lower bone mass at the whole body, lumbar spine and femoral neck and altered femoral neck geometry compared to normal weight women, and a trabecular bone score on the lower limit of normal. VO₂ₘₐₓ (L/min) was considered as strong determinant of bone parameters in young adult women regardless of their body mass index. The results of this first study suggest that increasing VO₂ₘₐₓ (L/min) is essential to prevent bone loss in underweight young women. The second study was conducted on young adult female mice subjected to voluntary wheel running and food restriction (50% of ad libitum intake) during 15 and 55 days. This study demonstrated that weight loss related to food restriction has a negative impact on cortical bone with few adverse effects on trabecular bone and is associated with an increase in the number of bone marrow adipocytes already after 15 days of restriction. This study also showed that voluntary wheel running exercise does not protect against changes in bone architecture and accumulation of bone marrow adiposity related to food restriction. Because ghrelin appeared as a potential regulator of bone marrow adiposity, the third study was conducted on young adult mice lacking the ghrelin receptor (Growth Hormone Secretagogue Receptor, Ghsr-/-) subjected to voluntary wheel running and food restriction (50% of ad libitum intake) during 21 days. This study demonstrated that ghrelin is a key mediator of food restriction - associated bone marrow adiposity expansion through activation of GHSR and that food restriction is necessary to reveal some differences in bone microarchitecture associated to GHSR invalidation.

L'agrégation de l’anémie dans un ménage est soulignée lorsque l’anémie touche l’ensemble du ménage. La littérature scientifique fait état d’une coexistence des facteurs nutritionnels et infectieux dans l’étiologie de l’anémie. Cependant, si la cause principale de l’anémie dans une population est la carence en fer, les enfants et les femmes seront beaucoup plus affectés que les hommes. Si par contre l’anémie est liée à une cause infectieuse qui touche toute la population, l’anémie atteindra également les hommes. Ce travail a été entrepris pour vérifier l’hypothèse selon laquelle l’anémie ne serait pas spécifique à la carence en fer dans le cas où elle se concentrerait à l’ensemble du ménage. Cette étude porte sur des données d’enquête collectées au Cameroun. Nos analyses sont basées sur un sous échantillon de 2331 sujets, dont 777 femmes, 777 hommes et 777 enfants. La prévalence de l’anémie était de 53,5% chez les enfants, 39,5% chez les femmes et 18,3% chez les hommes. L’anémie était concentrée dans 34% des ménages. Le programme SPSS version 17.0 et plus particulièrement l’analyse de régression logistique a servi à tester l’impact de chaque groupe de variables (facteurs liés à l’individu, au ménage et à la communauté) sur l’agrégation de l’anémie dans les ménages. Les résultats de cette étude suggèrent que l’agrégation de l’anémie s’observerait surtout quand la santé de l’enfant est compromise. Le risque d’agrégation y est 4 fois plus élevé dans les foyers où les enfants ont un déficit pondéral et 6 fois plus élevé dans les ménages où les enfants présentent une fièvre. Le fait d’appartenir au sud forestier et à un ménage de niveau socio-économique moyen constituerait également des facteurs de risque d’agrégation. / The aggregation of anemia in a household is underlined when the anemia affects the entire household. The involvement of dietary and infectious factors in the etiology of anemia was demonstrated in the literature. Nevertheless, if the main cause of anemia in a population is iron deficiency, children and women are much more affected than men. If instead of that, anemia is associated with an infectious cause that affects the entire population, anemia will also reach the men. This work was initiated to test the hypothesis that, anemia is not specific to iron deficiency when it affects the entire household. This study examines survey data collected in Cameroon. Our analysis is based on a sub sample of 2331 subjects, including 777 women, 777 men and 777 children. The prevalence of anemia was 58% in children, 48.48% for women and 20.82% for men. Anemia was found concentrated in 34% of households. The SPSS program version 17.0 and specifically the logistic regression analysis were used to test the impact of each group of variables (factors related to the individual, health, household and community) on the aggregation of anemia in the households. The results of this study suggest that the aggregation of anemia occurs mainly when the child's health is compromised. The risk of aggregation is four times higher in homes where children are underweight and 6 times higher in households where children have a fever. Being from the region of southern's forest and belong to a household with average socioeconomic level would also be the risks factors for the aggregation.

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