O termo vitamina D compreende um grupo de hormônios esteróides com ações biológicas semelhantes. O método mais acurado para determinar o estado de vitamina D é através dos níveis plasmáticos de 25 hidroxivitamina D [25(OH)D]. A deficiência de 25(OH)D é considerada um problema de saúde pública, tendo como principal causa à baixa exposição solar, idade avançada e doenças crônicas. A deficiência de 25(OH)D é frequente em pacientes com doença renal crônica (DRC) na fase não dialítica. Estudos têm evidenciado que os níveis séricos de 25(OH)D apresentam associação inversa com adiposidade corporal e resistência à insulina (RI) na população em geral e na DRC. O excesso de gordura corporal e o risco de Doença Cardiovascular (DVC) vêm sendo estudados em pacientes com DRC e dentre as complicações metabólicas associadas à adiposidade corporal elevada observa-se valores aumentados de HOMA-IR (Homeostasis Model Assessment of Insulin Resistance) um marcador para RI. Estudos avaliando o perfil da 25(OH)D na DRC na fase não dialítica, especialmente relacionados com a adiposidade corporal e RI são escassos. O presente estudo tem como objetivo avaliar a relação entre os níveis séricos de 25(OH)D, RI, e adiposidade corporal em pacientes com DRC na fase não dialítica. Trata-se de um estudo transversal observacional, incluindo pacientes adultos, clinicamente estáveis e com filtração glomerular estimada (FGe) &#8804; 60 ml/min., em acompanhamento regular no Núcleo Interdisciplinar de Tratamento da DRC. Os participantes foram submetidos à avaliação do estado nutricional por antropometria (peso, altura, índice de massa corporal (IMC), circunferências e dobras cutâneas) e absorciometria de duplo feixe de raios X (DXA); foram avaliados no sangue: creatinina, uréia, glicose, albumina, colesterol total e frações e triglicérides, além de leptina, insulina e 25(OH)D. Níveis séricos < 20ng/dL de 25(OH)D foram considerados como deficiência. As análises estatísticas foram realizadas utilizando-se o software STATA versão 10.0, StataCorp, College Satation, TX, USA. Foram avaliados 244 pacientes (homens n=135; 55,3%) com média de idade de 66,3 13,4 anos e de FGe= 29,4 12,7 ml/min. O IMC médio foi de 26,1 kg/m (23,0-30,1) com elevada prevalência de sobrepeso/obesidade (58%). A adiposidade corporal total foi elevada em homens (gordura total-DXA= 30,2 7,6%) e mulheres (gordura total-DXA= 39,9 6,6%). O valor mediano de 25(OH) D foi de 28,55 ng/dL (35,30-50,70) e de HOMA-IR foi 1,6 (1,0-2,7). Os pacientes com deficiência de 25(OH)D (n= 51; 20,5%) apresentaram maior adiposidade corporal total (DXA% e BAI %) e central (DXA%) e valores mais elevados de leptina. A 25(OH)D apresentou correlação significante com adiposidade corporal total e central e com a leptina, mas não se associou com valores de HOMA-IR. Estes resultados permitem concluir que nos pacientes DRC fase não dialítica a deficiência de 25(OH)D e a elevada adiposidade corporal são frequentes. Estas duas condições estão fortemente associadas independente da RI; a alta adiposidade corporal total e central estão positivamente relacionadas com RI; 25(OH)H e RI não estão associados nessa população com sobrepeso/obesidade. / The term vitamin D comprises a group of steroid hormones with similar biological actions. The status of vitamin D is most accurately determined by measuring the plasma levels of 25-hydroxyvitamin D [25(OH) D]. The deficiency of 25(OH)D is considered a public health problem and the main cause is the low sun exposure, advanced age and chronic diseases. Patients with chronic kidney disease (CKD) non dialysis dependent show high prevalence of 25(OH)D deficiency. The 25(OH)D serum levels have been described, in many studies, as being inversely associated with total and abdominal adiposity and insulin resistance. The higher risk for CVD related with excess of body fat have been studied in patients with CKD and the high values of HOMA-IR (Homeostasis Model Assessment of Insulin Resistance), a marker for insulin resistance (RI), are described as metabolic complication strongly associated with excessive body fat. Nevertheless, studies evaluating the 25(OH)D status in patients with CKD non dialysis dependent, and its association with body adiposity and IR are scarce. The present study aims to evaluate the relationship between the levels of 25(OH)D, IR and body fat in patients with CKD non dialysis dependent. This is an observational cross-sectional study including adult patients, clinically stable and with estimated glomerular filtration rate (FGE)&#8804; 60 mL/min. The studied population receives regular care at the Interdisciplinary Center for treatment of CKD. Participants underwent assessment of nutritional status by anthropometry (weight, height, body mass index (BMI), circumferences and skinfolds) and by DXA (Dual-energy X-ray absorptiometry); blood samples were also analysed for creatinine, urea, glucose, albumin, total cholesterol and triglycerides, 25(OH)D, leptin and insulin. Levels of 25(OH)D <20ng/dL were considered deficient. Statistical analyzes were performed using STATA version 10.0 software, StataCorp, CollegeSatation, TX, USA. We evaluated 244 patients (men n= 135; 55.3%) with a mean age of 66.3 13.4 years and eGFR= 29.4 12.7 mL/min. The mean BMI was 26.1 kg/m (23.0 to 30.1) with a high prevalence of overweight/obesity (58%). Total body fat was high in men (total body fat by DXA= 30.2 7.6%) and women (total body fat by DXA= 39.9 6.6%). The median value of 25(OH)D was 28.55 (35.30 to 50.70) ng/dL and HOMA-IR was 1.6 (1.0 to 2.7) and patients with deficiency of 25(OH D n= 51 - 20.5%) had higher total (DXA% and BAI%) and central adiposity (DXA%) and higher levels of leptin. The 25(OH)D showed an inverse correlation with the total and central body fat and leptin, but was not associated with HOMA-IR values. These results allow to conclude that patients with CKD, non dialysis dependent, show deficiency of 25(OH)D and high body adiposity. These two conditions are strongly associated independent of the IR; the high total and central body adiposity is positively related with IR; the 25(OH)H and IR are not associated in this overweight/obese population.

A hiperglicemia crônica no diabetes está relacionada com distúrbios nas vias de sinalização da insulina e do mTOR, e com o desbalanço na secreção de adipocinas pelo tecido adiposo branco (TAB). Em longo prazo, esta disfunção metabólica pode causar uma perda severa de massa adiposa, o que agrava a resistência à insulina (RI). Estudos têm destacado o potencial efeito da suplementação com leucina no tratamento de doenças metabólicas como o diabetes tipo 2 e obesidade. No entanto, os efeitos da leucina sobre a homeostase glicêmica e a sensibilidade à insulina em doenças em que ocorre perda severa de gordura ainda necessitam melhores esclarecimentos. Portanto, foi investigado se a suplementação crônica com leucina pode afetar a adiposidade de ratos diabéticos com perda intensa de TAB, e melhorar a RI e outras desordens metabólicas relacionadas com TAB. Ratos recém-desmamados foram distribuídos em 3 grupos: i) Grupo controle (C) - não diabético e recebiam ração controle; ii) Grupo diabetes (D) - diabético e recebiam ração controle; iii) Grupo diabetes Leucina (DL) - diabético e recebiam ração suplementada com 5% de L-leucina. Após 8 semanas, foram analisados: glicemia e insulinemia de jejum, HOMAIR, citocinas pro- e anti-inflamatórias no soro e tecido adiposo branco, expressão de proteínas (mTOR, p-MTOR, p70S6K1, p-p70S6K1, PPAR&#947, C/EBP&#945;, ACC1, FAS, AKT, p-AKT) nos tecidos adiposos subcutâneo (SC) e retroperitoneal (RP), bem como a expressão de RNAm da adiponectina e leptina no TAB. In vivo, foram realizados testes de tolerância oral à glicose (OGTT) e de sensibilidade à insulina (ITT), glicemia pós prandial e consumo de ração. O tratamento crônico com leucina reverteu a perda de massa adiposa dos coxins subcutâneo e viscerais neste modelo experimental, o que pode ser explicado pelo aumento da expressão da p-p70S6K1, PPAR&#947;, ACC1 e FAS, proteínas que estimulam a adipogênese e lipogênese de novo nos adipócitos. Além disso, houve um aumento da expressão de AKT total no coxim SC no grupo DL, mas não foi alterada no coxim RP, indicando que a leucina também pode melhorar a resistência à insulina por ativar a AKT, que é considerada enzima limitante da cascata de fosforilação da insulina. Por outro lado, a leucina melhorou o perfil de adipocinas secretadas pelo coxim RP, pois aumentou a secreção de adiponectina e IL-10. Estas citocinas, direta ou indiretamente, reduzem a RI em tecidos como fígado, TAB e músculo esquelético. Isto sugere que a ação da leucina sobre a sensibilidade à insulina no coxim subcutâneo parece estar mais relacionada com a recuperação da via de sinalização da insulina, ao passo que, no coxim RP está indiretamente relacionada com a melhora do perfil de adipocinas secretadas por este tecido. Estes dados corroboram com os resultados de HOMAIR, glicemia de jejum e pós prandial, OGTT e ITT, nos quais foi observada uma significativa melhora do quadro de intolerância à glicose e resistência à insulina em ratos diabéticos tratados com leucina. Em conclusão, a suplementação crônica com leucina aumentou a adiposidade corporal em ratos diabéticos induzido por estreptozotocina no período neonatal, o que foi relacionado com a melhora da intolerância à glicose e da resistência à insulina. Isto demonstra que a recuperação trófica do tecido adiposo branco é fundamental para a melhora dos distúrbios metabólicos relacionados ao metabolismo da glicose neste modelo experimental. / The chronic hyperglycemia in diabetes is associated with disturbances in insulin and in mTOR pathways, and changes in adipokine secretion in white adipose tissue (WAT). Long-term, this metabolic dysfunction can cause a severe loss of fat mass, which increases insulin resistance (IR). Studies have highlighted the effect of leucine supplementation in treatment of metabolic diseases as type 2 diabetes and obesity. However, the effects of leucine on glucose homeostasis and insulin sensitivity in diseases with intense fat loss remain unknown. Therefore, was investigated whether chronic leucine supplementation can affect the adiposity of diabetic rats with severe adipose tissue loss, and to improve the IR and other metabolic disorders associated with WAT. After weaning, rats were distributed in 3 groups: i) control group (C) - no diabetic and received control chow ; ii) diabetes group (D) - diabetic and received control chow; iii) Leucine Diabetes Group (DL) - diabetic and received diet supplemented with 5% L-leucine. After 8 weeks, were analyzed: fasting glycaemia and insulin, HOMA>IR, antiinflammatory and proinflammatory cytokines in serum and in WAT, protein expression of mTOR, p-MTOR, p70S6K1, p-p70S6K1, PPAR&#947;, C/EBP&#945;, ACC1, FAS, AKT, p-AKT in subcutaneous (SC) and retroperitoneal adipose tissue, as well as the RNAm expression of adiponectin and leptin in WAT. In vivo, were realized oral glucose tolerance test (OGTT) and insulin sensitivity test (ITT), postprandial glycaemia and chow ingestion. O chronic treatment with leucine recovered the adipose mass in subcutaneous and visceral fat pad in this experimental model, this was explicated by increase of protein expression of p-p70S6K1, PPAR&#947;, ACC1 and FAS that stimulate the adipogenesis and de novo lipogenesis in adipocytes. Moreover, had an increase of protein expression of total AkT in subcutaneous fat pad in group DL, but don\'t change in RP fat pad, indicating that the leucine can to activate the AKT, which is limiting enzyme of phosphorylation cascade of insulin, and improve the insulin resistance. On the other hand, leucine improved the profile of adipokines secreted in RP fat pad, because increased the secretion of adiponectin and IL-10. This cytokines reduced the insulin resistance in tissues as liver, WAT and skeletal muscle. This suggest that action of leucine on insulin sensitivity in subcutaneous fat pad is more related to recovery of insulin signaling, and in RP fat pad is indirectly related to improve of profile of adipokines secretion in this tissue. This data corroborates with results of HOMAIR, postprandial and fasting glycaemia, OGTT and ITT, which showed significant improve of glucose intolerance and insulin resistance in diabetic rats treated with leucine. In conclusion, the chronic leucine supplementation increased adiposity in streptozotocin-induced diabetic rats in neonatal period, which was related to improve of glucose intolerance and insulin resistance. This show that trophic recovery of white adipose tissue is important for improve of metabolic disturbances related to glucose metabolism in this experimental model.

There is substantial evidence from cellular, animal and epidemiological studies in support of a role for calcium, and in particular, dairy foods in the regulation of weight (McCarron, 1983; Davies et al. 2000; Heaney, 2003a; Jacqmain et al. 2003; Parikh & Yanovski, 2003; Soares et al. 2004a; Azadbakht et al. 2005). These studies suggest, but do not provide, a causal link between increased calcium intake and reduced adiposity. In contrast, randomised controlled trails (RCT) are limited and their outcomes, to date, are conflicting in their findings (Zemel et al. 2004b; Harvey-Berino et al. 2005; Thompson et al. 2005; Zemel et al. 2005a; 2005b). The primary mechanism involves the control of intracellular calcium by calcitrophic hormones, vitamin D3 and PTH. It is proposed that a higher calcium intake lowers the calcitrophic hormones, thus reducing intracellular calcium and attenuating lipid storage (Zemel et al. 2000). Other flow through effects may include the greater utilisation of fat as a fuel source, increased thermogenesis, increased fat excretion, improved satiety and reduced food intake. (Melanson et al. 2003; Sun & Zemel, 2004; Boon et al. 2005a; Gunther et al. 2005b; Jacobsen et al. 2005b; Melanson et al. 2006). In this thesis we demonstrate that the acute ingestion of calcium, increased postprandial fat oxidation in overweight and obese humans. The results were consistent between the two sources of calcium tested (dairy and calcium citrate). Circulating levels of non-esterified fatty acids (NEFA) were less suppressed, while glycerol tended to be higher following both high calcium meals (Cummings et al. 2006). / There was no evidence of a modulation of subjective feelings of hunger, or satiety, nor immediate food intake (buffet) or 24 hour food intake. A prolongation of the inter-meal interval was however observed in subjects consuming the high calcium meals. A single-blind 12 week RCT, with a 12 week wash out period, compared two energy restricted (ER) diets either high (HC 1200 mg/d) or low in calcium (LD 600 mg/d). Forty overweight/obese male and female subjects were recruited for the study with 29 subjects completing both arms of the study. Anthropometric data and body composition from DEXA were measured before, during and following each diet. There was no difference between the diets in the loss of body weight, total fat mass or trunk fat mass. A greater reduction in waist circumference of 1.23 cm was observed when subjects had consumed the HC diet; this however was just short of significance (P=0.052). There was a smaller reduction of resting energy expenditure on the hypocaloric HC diet with a trend for a greater fat oxidation at week 10 of intervention. No differences were observed between the treatment groups for fasting levels of glucose, insulin, Hba1c, LDL-C, HDL-C or TC. We also found an inverse relationship between resting metabolic rate at the start of ER and body fat lost when subjects consumed the LC diet, but not the HC diet. / This is a novel finding in that it would be expected to see an inverse relationship between initial RMR and the amount of fat lost; however, the HC diet seems to achieve the same fat loss as the LC diet by taking away the effect of initial body size/composition. Overall, the ingestion of a single meal containing 500 mg of dietary and elemental calcium has some benefits for the obese individual. Six hours post-prandially fat oxidation is stimulated following the consumption of the dietary and elemental calcium breakfast meals. During a 12-week weight loss period, a higher calcium intake did not result in a greater weight loss compared to a low calcium diet. The HC diet did result in a trend for a greater reduction in waist circumference; however, this did not transcribe into an increased loss of total or regional body fat.

Research Doctorate - Doctor of Philosophy (PhD) / Maternal factors prior to conception and during pregnancy may influence the development of the metabolic, cardiovascular and endocrine systems of the offspring and subsequent disease pathogenesis. This thesis explores the concept of the developmental origins of health and disease. Human observational research studies were undertaken to test the relationships amongst maternal dietary intake, weight gain during pregnancy and changes in biochemical markers between pregnancy and postpartum for the mother and infant. This thesis presents three chapters of original research related to maternal and fetal nutrition, and one chapter of empirical data concerning the methodological challenges faced when recruiting for research purposes. An analysis of dietary intake data from the young cohort of the Australian Longitudinal Study on Women’s Health was used to determine the overall diet quality in a contemporary cohort, and to assess whether those who are pregnant eat differently to those who are not. Only small differences in diet quality and nutrient intakes were detected between pregnancy groups, and diet quality scores were consistently low. When the intake data were compared to Australian recommendations it appears that many young women fail to reach key nutrient targets, including those set for folate, fibre, calcium, iron, potassium and vitamin E. The research focus then shifted to prospective longitudinal data collection for women and their children during pregnancy and after birth. Low recruitment to this component of the studies threatened the potential to achieve the research aims. Rather than jeopardising the power of the investigations efforts were made to understand what had gone wrong and how the situation could be rectified. An investigation of the relationship between fetal adiposity and maternal weight changes in pregnancy was performed. Pre-pregnancy body mass index (BMI) and weight changes during pregnancy were taken as broad markers of maternal nutritional status and energy regulation. Intrauterine growth, including the accumulation of adipose tissue, was assessed using serial ultrasounds. Fetal size was positively related to maternal pre-pregnancy weight (and BMI) and weight gain (change in BMI) during pregnancy. Maternal pre-pregnancy weight was positively associated with adiposity at the fetal abdomen, but not the thigh. However, overall maternal weight gain was not associated with fetal adiposity. To determine whether maternal vitamin B12 and folate (methyl donors) in pregnancy could influence the offspring’s homocysteine metabolism at birth, changes in plasma vitamin B12, plasma folate and red cell folate were characterised for the cohort of more than 100 women during pregnancy and up to six months after birth. A small sub-sample of infants also had blood collected at six months postpartum. Average maternal plasma folate during pregnancy was significantly predictive of infant plasma homocysteine. In conclusion, the research outlined herein demonstrates important interactions between the mother and her offspring during the critical windows of early development. The research is multidisciplinary in its application and contributes to our understanding of some of the nutritional influences in pregnancy and postpartum for women and their children.

BACKGROUND: Risk factors associated with Metabolic Syndrome (MetS) have been implicated in cardiovascular disease (CVD) development and outcomes. Few studies have investigated relationships between psychological variables, MetS factors, and indices of cardiac structure and function (CSF) among healthy individuals in a single conceptual model. No studies to date have analyzed such relationships in patients with CVD. METHODS: The present study examined associations between cynical hostility (CynHo), MetS factors, and CSF in 186 multi-ethnic post-myocardial infarction (MI) patients. Structural equation modeling was used to test a theory driven model of MetS that had good statistical fit. Primary MetS variables included waist circumference (WC), the homeostatic model of insulin resistance (HOMA-IR), glucose area under the curve (G-AUC), triglycerides (TRIG), high-density lipoprotein cholesterol (HDL-C), and diastolic blood pressures (DBP). Secondary MetS variables included plasminogen activator inhibitor-1 (PAI-1) and a latent inflammation variable comprised of CRP and IL-6. Cardiac function variables were fractional shortening (FS), E/A ratio, and rate-pressure product (RPP). A latent cardiac mass (CM) variable was also created. RESULTS: The final structural model had good model fit (Chi-Square(102)=100.65, p=0.52, CFI=1.00, RMSEA=0.00, and SRMR=0.04). Direct paths were supported between WC and CM and all MetS factors except TRIG and G-AUC. WC was indirectly associated with DBP via CM. The model supported positive direct paths between HOMA-IR and G-AUC, TRIG, and PAI-1, but not inflammation or HDL-C. HOMA-IR demonstrated a direct positive association with RPP and direct inverse associations with FS and E/A ratio. No direct paths were supported between other MetS variables except one between TRIG and HDL-C. CynHo demonstrated a direct positive relationship with HOMA-IR. CONCLUSIONS: Similar to findings in healthy individuals, central adiposity and IR play primary roles in CSF impairment in post-MI patients. Findings suggest that CynHo could promote the progression of metabolic dysfunction and cardiac disease via factors that influence the efficiency of glucose metabolism. Interventions for post-MI patients should take into account both direct and indirect effects of CynHo, central adiposity, and IR on the progression of CVD in this population to reduce adverse outcomes and improve quality of life.

Als Resultat überhöhter Energieaufnahme und zu geringen Energieverbrauchs beobachten wir eine über das normale Maß hinausgehende Akkumulation von Fettgewebe, die sich als Adipositas manifestiert. Sie gilt als einer der Hauptrisikofaktoren für Krankheiten des metabolischen Syndroms. Im Rahmen von Prävention, Diagnose und Therapie der Adipositas, muss ihr wesentliches Charakteristikum; der individuelle Körperfettanteil; einer Messung zugänglich gemacht werden. Eine direkte Bestimmung der Körperzusammensetzung erlauben die Neutronenaktivierungsanalyse und die chemische Analyse. Beide Verfahren sind sehr genau, aber aufwendig und kostenintensiv und darüber hinaus die chemische Analyse nur am menschlichen Cadaver praktizierbar. Um dennoch die Körperzusammensetzung hinreichend genau bestimmen zu können, wurden zahlreiche indirekte Messverfahren entwickelt. Man kann sie in Labor- und Feldmethoden untergliedern. Die Labormethoden bestechen durch hohe Genauigkeit und Reproduzierbarkeit, sind aber zumeist aufwendig und teuer. Feldmethoden sind im Gegensatz dazu leicht anwendbar, transportabel und preiswert, weisen aber eine weniger hohe Genauigkeit und Reproduzierbarkeit auf.<br><br> In der vorgestellten Arbeit wird über eine jüngere Entwicklung, die das Prinzip der unterschiedlichen Leitfähigkeit für den elektrischen Strom durch die verschiedenen Gewebe des Körpers nutzt, berichtet. Der Prototyp eines Gerätes wurde innerhalb eines von der EU geförderten multizentrischen Projekts entwickelt und auf seine Einsatzfähigkeit und Qualität hin geprüft. Der Schwerpunkt der Arbeit liegt auf der Einschätzung der Körperzusammensetzung normal- und übergewichtiger Probanden mit der neu entwickelten Technik. Das vorliegende Studiendesign diente nicht nur der Beurteilung der neuen Technik die Körperzusammensetzung und Veränderungen dieser zu erfassen, sondern darüber hinaus, etablierte Methoden hinsichtlich ihrer Genauigkeit zu bewerten. Bezüglich ihrer Anwendbarkeit und Reproduzierbarkeit hat die neue Methode Hoffnung geweckt, sich als eine Feldmethode zu etablieren. Auf der anderen Seite zeigte sich in Abhängigkeit der Gesamtkörperfettmasse eine Überschätzung der Zielgröße im Vergleich zur Referenzmethode (dual energy x ray absorptiometry (DXA)). Die Abweichungen waren dabei gerade für das einzelne Individuum sehr groß. Technische Verbesserungen und die Entwicklung spezifischer Regressionsgleichungen könnten in Zukunft zu einer wesentlichen Verbesserung der neuen Methode beitragen.<br><br> Die Labormethode "Air Displacement Plethysmography" konnte durch die guten Übereinstimmungen der Ergebnisse mit denen der Referenzmethode DXA und die einfache Anwendung überzeugen. Sie stellt eine durchaus konkurrenzfähige Alternative zur Hydrodensitometrie dar, die noch heute als "goldener Standard" zur Erfassung der Körperzusammensetzung akzeptiert wird. Im Verlauf der durchgeführten Studie stellte sich heraus, dass die Hydrodensitometrie sehr hohe Anforderungen an den Probanden stellt. Das Untertauchen des gesamten Körpers unter Wasser in Kombination mit einer maximalen Ausatmung erwies sich als sehr problematisch. Die dabei auftretenden Fehler schlugen sich in der Berechnung der Gesamtkörperfettmasse des einzelnen Individuums wieder und führten zu zum Teil erheblichen Abweichungen der Ergebnisse von denen der Referenzmethode.<br><br> Die Feldmethoden bioelektrische Impedanzanalyse und Hautfaltendickenmessung erwiesen sich als kostengünstige und leicht anwendbare Methoden. Die Ergebnisse beider Methoden stimmten im Mittel gut mit den Ergebnissen der Referenzmethoden überein. Dennoch zeigte die BIA größere Abstriche in der Beurteilung der Gesamtkörperfettmasse des einzelnen Individuums und bei der Dokumentation von Veränderungen der Gesamtkörperfettmasse. Die Hautfaltendickenmessung stellt – wendet man sie korrekt an – eine Methode dar, die sowohl die Gesamtkörperfettmasse als auch Veränderungen dieser gut erfassen kann. In Abhängigkeit der geforderten Genauigkeit kann diese Methode für die Erfassung der Körperzusammensetzung empfohlen werden.<br><br> Demnach bleibt die Frage unbeantwortet, inwieweit die indirekten Methoden in der Lage sind, die "wahre" Körperzusammensetzung adäquat zu erfassen. Jede neu entwickelte Methode – die möglichst viele Vorteile in sich vereint – wird wieder vor dem Problem stehen: eine geeignete und dabei praktikable Referenzmethode zu finden, die die wahre Körperzusammensetzung zu bestimmen in der Lage ist. Daher sollte neben dem Streben nach der Entwicklung einer Methode, die genau und leicht anwendbar ist, das Hauptaugenmerk auf die Überarbeitung der zugrunde liegenden Modellvorstellungen und die Verbesserung von Regressionsgleichungen gelegt werden. / Western industrial countries are characterized by sedentary lifestyle and a high-fat and simple carbohydrate diet. Decrease physical activity and increase energy intake are leading to an epidemic increase of overweight and obesity. Obesity is defined as the presence of excess adipose tissue and has been associated with an increased risk for diseases of the metabolic syndrome. Thus, the importance of obtaining reliable and accurate body fat estimates is essential not only for the prevention, but also for the diagnosis and therapy of obesity. Direct chemical analysis is the most definitive method for determining human body composition. The few data obtained on the composition of adult bodies stemmed from cadaver analyses, dated back to 1945 and 1956. These results contributed greatly to the actual fundamental knowledge about human body composition. Obviously, the method is limited by the precondition of needing the human cadaver and the high complexity of the analyses. Because of this limitation, indirect methods have been developed during the last decades. To date more than ten methods to estimate body composition in vivo are available. The methods can be generally organized into two groups: laboratory and fields methods. Laboratory methods have high accuracy and reproducibility, but are complex and very expensive, whereas field methods are easy to use and economically priced, but less accurate. A new device that combines the positive features of both, laboratory and field methods is needed . An already existing method - Total Body Electrical Conductivity (TOBEC) - meets the requirements for such new device. The technique is based on the principle, that lean tissue is far more electrically conductive than fat, due to the higher content of electrolytes in the fat-free mass. The difference between impedance when a subject is inside and outside of the generated field is an index of the total electrical conductivity of the body, which, in turn is proportional to the lean body mass of the subject.<br><br> Within the European Project BodyLife (IST - 2000 - 25410) a new field method for estimation the human body composition was developed. To assess the suitability of the new technique the present study aimed to evaluate the reliability of nTOBEC and to validate it against established laboratory and field methods.<br><br> Within the project the development of the new method (nTOBEC) succeeded to combine the TOBEC-principle, and additionally, to be transportable and easy to use.<br><br> The high reliability coefficients found in this investigation indicate that nTOBEC is an extremely reliable instrument. By application the new technique we observed a significant overestimation of total body fat mass compared the reference method dual energy x ray absorptiometry (DXA) in both, males and females. However, nTOBEC could document changes in total body fat mass during a weight loss intervention trial.<br> Our data suggest nTOBEC deserves further investigation with the intention of establishing nTOBEC as a non-invasive method for accurately quantifying total body fat mass.<br> Aside from these results we observed accurate results for the easy to use laboratory method "air displacement plethysmography" compared to the results measured by DXA. Furthermore, the field methods - bioelectrical impedance analysis and skinfold thickness measurement – produced good results compared to the reference method.

Adiposity has been linked to impaired respiratory function in adults but whether the distribution of adipose tissue has a differential effect on pulmonary function is still uncertain. Moreover, in children, the relationship between adiposity and lung dysfunction is not clearly understood. A two-stage multivariate analysis was conducted using data from 5604 Canadians aged 6 to 79 years who participated in the Canadian Health Measures Survey (CHMS). The associations of various anthropometric and skinfold measures with lung function were examined separately in adults and children. After adjustment of covariates, waist circumference and subscapular skinfold thickness showed the strongest inverse associations with FVC and FEV1 in men. In women, BMI and sum of five skinfolds had the largest impact on pulmonary function. FVC and FEV1 in boys were most affected by waist-to-hip ratio and triceps skinfold. In girls, adiposity was not linked to the lung function testing variables. Adiposity measures have differing effects on respiratory function depending on age and sex group.

Over the past 30 years, obesity has been primarily identified by the body mass index (BMI). Due to its ease of calculation, the BMI has become the most widely used diagnostic tool to identify weight problems. This study examined the association between hypertension and BMI in White, Black, and Hispanics in the United States. The study’s hypothesis was that this relationship was weaker in Blacks than in the other groups. Data for the study came from the 2007-2008 and 2009-2010 National Health and Nutrition Examination Surveys. The association was weaker in Black men than in Whites or Hispanics on a univariate basis, and at most BMI levels on a multivariate basis. For females, it was also weaker in Blacks at most BMI levels on a univariate basis. However, multivariate logistic regression analysis did not indicate that the hypothesis held for Black women when adding covariates to the models.

Weight loss has been shown to significantly improve Adipose tissue (AT) function, however changes in AT gene expression profiles particularly in visceral AT (VAT) have not been systematically studied. Here, we tested the hypothesis that extensive weight loss in response to bariatric surgery (BS) causes AT gene expression changes, which may affect energy and lipid metabolism, inflammation and secretory function of AT. We assessed gene expression changes by whole genome expression chips in AT samples obtained from six morbidly obese individuals, who underwent a two step BS strategy with sleeve gastrectomy as initial and a Roux-en-Y gastric bypass as second step surgery after 12 ± 2 months. Global gene expression differences in VAT and subcutaneous (S)AT were analyzed through the use of genome-scale metabolic model (GEM) for adipocytes. Significantly altered gene expressions were PCR-validated in 16 individuals, which also underwent a two-step surgery intervention. We found increased expression of cell death-inducing DFFA-like effector a (CIDEA), involved in formation of lipid droplets in both fat depots in response to significant weight loss. We observed that expression of the genes associated with metabolic reactions involved in NAD+, glutathione and branched chain amino acid metabolism are significantly increased in AT depots after surgery-induced weight loss.

Nutrient deprived diets are major contributors to the development of childhood obesity and metabolic diseases. Total and site-specific adiposity, such as visceral and skeletal muscle fat, have been associated with an increased risk of metabolic syndrome, insulin resistance, and other cardiometabolic risk factors in youths. C-reactive protein (CRP), a circulating inflammatory biomarker, is an established risk factor for cardiovascular disease and is associated with adiposity even at a young age. Diet quality indexes have been developed for use in adolescents and have evaluated the relationships between diet quality and selected health outcomes. Studies that assess relationships between diet quality, adiposity measured using direct methods, and metabolic risk are lacking in youth, particularly Hispanic Americans. Therefore, the objective of this dissertation was to evaluate the relationships between diet quality, assessed by the Youth Healthy Eating Index (YHEI), measures of total and site-specific adiposity, by dual-energy x-ray absorptiometry (DXA) and peripheral quantitative computed tomography (pQCT), and inflammation, assessed by high-sensitivity CRP (hs-CRP) in a cross-sectional study at baseline of 576 healthy Hispanic American and non-Hispanic girls aged 8-13 years. Diet was assessed using the validated semi-quantitative Harvard Youth/Adolescent Food Frequency Questionnaire (YAQ). Diet quality was assessed from the YHEI, developed based on the YAQ. Muscle density (mg/cm³), a surrogate for fat infiltration, was measured at tibial and femoral sites using pQCT. Total body and android fat (surrogate for visceral fat) were measured by DXA. Serum hs-CRP concentrations were measured by nephelometry. Multiple linear and logistic regression analyses were employed to assess these relationships. Total YHEI score was inversely associated with total body fat percent (p= 0.01) and android percent fat (p= 0.02), but not body mass index (BMI) or muscle density. Lower "margarine and butter use" and higher "meat ratio" were associated with higher leg muscle density. Higher "meat ratio" was inversely associated with BMI and greater "multivitamin use" was inversely associated with visceral adiposity. In a subsample of 113 Hispanic girls, over 50% of study participants demonstrated non-detectable serum hs-CRP levels. In adjusted models, there was no significant relationship between overall YHEI score and hs-CRP in this sample of adolescent girls. For every 1-unit increase in "whole grains" score there was a 44% increase in odds of being in the "high" category compared to the "undetectable" category of hs-CRP, after adjusting for maturity offset, PYPAQ score, total energy intake, total body fat, and all other individual YHEI components (OR: 1.44, 95% CI: 1.06, 1.97). The odds of being in the "high" category of hs-CRP were 38% higher compared to those with "non-detectable" hs-CRP for every 1-kg/m² increase in BMI (OR: 1.33, 95% CI 1.16, 1.53, p<0.0001). The odds of being in the "high" hs-CRP category increased with every 5 percent unit increase in total body percent fat (OR: 2.38, 95% CI 1.58, 3.58, p<0.0001) and android percent fat (OR: 1.89, 95% CI 1.39, 2.57, p<0.0001), compared to those with "non-detectable" concentrations. Calf muscle density was associated with lower odds of elevated hs-CRP compared to the "non-detectable" group (OR: 0.58, 95% CI 0.35, 0.75, p<0.001). The findings suggest that higher diet quality scores are associated with lower total and visceral body fat in adolescent girls. While greater total and regional adiposity are associated with increased inflammation, independent of biological and lifestyle factors, diet quality is not significantly associated with inflammation, as assessed by concentrations of hs-CRP, in Hispanic American girls.