Diss. (sammanfattning) Stockholm : Karolinska institutet, 2005. / Härtill 5 uppsatser.

The entire dissertation/thesis text is included in the research.pdf file; the official abstract appears in the short.pdf file (which also appears in the research.pdf); a non-technical general description, or public abstract, appears in the public.pdf file. Title from PDF of title page (University of Missouri--Columbia, viewed on January 5, 2010). Thesis advisor: Paul J. Fadel. "December 2009" Includes bibliographical references.

While genome‐wide association studies as well as candidate gene studies have revealed a great deal of insight into the contribution of genetics to obesity development and susceptibility, advances in adipose tissue research have substantially changed the understanding of adipose tissue function. Its perception has changed from passive lipid storage tissue to active endocrine organ regulating and modulating whole‐body energy homeostasis and metabolism and inflammatory and immune responses by secreting a multitude of bioactive molecules, termed adipokines. The expression of human vaspin (serpinA12) is positively correlated to body mass index and insulin sensitivity and increases glucose tolerance in vivo, suggesting a compensatory role in response to diminished insulin signaling in obesity. Recently, considerable insight has been gained into vaspin structure, function, and specific target tissue‐dependent effects, and several lines of evidence suggest vaspin as a promising candidate for drug development for the treatment of obesity‐related insulin resistance and inflammation. These will be summarized in this review with a focus on molecular mechanisms and pathways.

Thesis (PhD)-- Stellenbosch University, 2014. / ENGLISH ABSTRACT: Introduction: The cardioprotective actions of the hormone melatonin against myocardial ischaemiareperfusion injury (IRI) are well-established. It has recently been shown to prevent the harmful effects of hyperphagia-induced obesity on the susceptibility of the heart to IRI as well as many of the harmful effects of obesity and insulin resistance. However, the exact mechanism whereby it exerts its beneficial action is still unknown. The aims of this study were to determine the effects of relatively short-term melatonin treatment in a rat model of diet-induced obesity on: (i) biometric and metabolic parameters, lipid peroxidation, myocardial IRI and intracellular signalling (ii) mitochondrial oxidative phosphorylation function (iii) cardiomyocyte glucose uptake and intracellular signalling. In addition, the effects of acute melatonin treatment of cardiac microvascular endothelial cells (CMEC) were determined on cell viability, nitric oxide production (NO), TNF- -induced dysfunction and intracellular signalling. Material and Methods: Male Wistar rats were randomly allocated to two groups for 20 weeks feeding with either standard rat chow or a high calorie diet. Each group was subdivided into 3 groups receiving either water throughout or melatonin (4mg/kg/day, in the drinking water) for the last 6 or 3 weeks of the experimental programme. Hearts, perfused in the working mode, were subjected to ischaemia/reperfusion and infarct size determined. Mitochondria and cardiomyocytes were isolated according to standard techniques and oxidative function and glucose uptake respectively determined. CMEC NO production and cell viability were quantified by FACS analysis of the fluorescent probes, DAF-2/DA and propidium iodide/Annexin V respectively. Intracellular signalling was evaluated using Western blot and appropriate antibodies. Results: The high-calorie diet caused significant increases in body weight gain, visceral adiposity, fasting blood glucose, serum insulin, triglycerides, HOMA-IR index and a concomitant reduction in serum adiponectin levels as well as larger myocardial infarct sizes after exposure to IRI compared to the control, indicating increased susceptibility to damage. Three as well as six weeks of melatonin administration to obese and insulin resistant rats reduced serum insulin levels and the HOMA-IR index. Myocardial infarct size was reduced in both control and diet groups. These effects were associated with increased activation of baseline myocardial STAT- 3 and the RISK pathway during reperfusion. The diet had no effect on the oxidative phosphorylation capacity of mitochondria, isolated from non-perfused hearts (baseline), but melatonin administration for 6 weeks induced a reduction in state 3 respiration rate; mitochondria isolated from diet hearts subjected to global ischaemia, exhibited an attenuated oxidative phosphorylation process which was improved by melatonin treatment. Melatonin in vitro enhanced cardiomycyte insulin stimulated glucose uptake of normal young rats but not of insulin resistant rats. In vivo melatonin treatment for 6 weeks increased basal (in diet group) and insulin stimulated glucose uptake in both control and diet groups. Melatonin (1nM) in vitro caused a significant reduction in necrosis and apoptosis of cultured CMEC, associated with a decrease in nitric oxide availability and eNOS activation and a concomitant increase in PKB/Akt, p38MAPK and AMPK activation. The harmful effects of TNF- treatment on signalling in CMEC could be prevented by co-treatment with melatonin. Conclusions: The results suggest that short-term melatonin treatment was able to significantly attenuate the diet-induced increased myocardial susceptibility to ischaemia/reperfusion damage. It may also improve cardiac glucose homeostasis and mitochondrial oxidative phosphorylation in an insulin resistant state. Melatonin in vitro protects CMEC against apoptosis and necrosis and reduces nitric oxide availability. These beneficial effects of melatonin may ultimately be due to its antioxidant capacity or receptor-mediated actions, but this remains to be established. / AFRIKAANSE OPSOMMING: Inleiding: Die vermoë van die hormoon, melatonien, om die hart teen iskemie/ herperfusiebesering (IHB) te beskerm, is welbekend. Onlangs is ook getoon dat melatonien IHB en verskeie van die nadelige effekte van vetsug en insulienweerstandigheid in hiperfagiegeïnduseerde vetsug kan voorkom. Die meganisme(s) betrokke by hierdie voordelige prosesse is egter grootliks onbekend. Die doel van hierdie studie was om die gevolge van korttermyn melatonienbehandeling in ‘n model van hiperfagiegeïnduseerde vetsug te ondersoek op (i) biometriese en metaboliese parameters, lipiedperoksidasie, miokardiale IHB en intrasellulêre seintransduksie, (ii) mitochondriale oksidatiewe fosforilasie, (iii) glukoseopname en intrasellulêre seintransduksie in kardiomiosiete en aanvullend, (iv) die invloed van akute melatonienbehandeling van kardiale mikrovaskulêre endoteelselle op sellulêre oorlewing, stikstofoksiedproduksie, TNF- - geïnduseerde disfunksie en seintransduksie. Metodiek: Manlike Wistarrotte is ewekansig in twee groep verdeel en vir 20 weke met standaard-rotkos of ‘n hoëkaloriedieet gevoer. Elke groep is in 3 subgroepe verdeel, wat deurgaans water of melatonien (4mg/kg/dag in die drinkwater) vir 3 of 6 weke voor die beëindiging van die eksperiment ontvang het. Harte is geperfuseer volgens die werkharttegniek, blootgestel aan iskemie/herperfusie en die infarktgrootte bepaal. Mitochondria en kardiomiosiete is volgens standaardtegnieke geïsoleer vir bepaling van oksidatiewe funksie en glukoseopname respektiewelik. NO produksie en sellewensvatbaarheid was gekwantifiseer deur vloeisitometriese analises (FACS) van die fluoresserende agense, DAF-2/DA en propidium jodied/Annexin V onderskeidelik. Intrasellulêre seintransduksie is evalueer met behulp van die Western kladtegniek en geskikte antiliggame. Resultate: Die hoëkaloriedieet het ‘n beduidende toename in liggaamsgewig, visserale vet, vastende bloedglukose, seruminsulienvlakke, trigliseriede, HOMA-IR-indeks en ‘n gepaardgaande verlaging in serumadiponektienvlakke tot gevolg gehad, sowel as groter miokardiale infarkte na iskemie/herperfusie. Laasgenoemde dui op ‘n groter vatbaarheid vir iskemiese beskadiging in harte van vetsugtige diere. Drie sowel as ses weke van melatonienbehandeling het die seruminsulienvlakke en HOMAindeks in vetsugtige diere beduidend verlaag, vergeleke met die kontroles. Miokardiale infarktgroottes was verminder in beide kontrole- en vetsuggroepe. Hierdie effekte het met ‘n verhoogde aktivering van basislyn STAT-3 en PKB/Akt en ERKp44/p42 tydens herperfusie gepaard gegaan. Die dieet het geen invloed op die oksidatiewe fosforilasiekapasiteit van mitochondria, geïsoleer uit harte van ongeperfuseerde harte, gehad nie (basislyn), maar melatonienbehandeling vir 6 weke het Staat 3 respirasie verlaag. Mitochondria, geïsoleer uit harte van vetsugtige rotte wat aan globale iskemie onderwerp was, het ‘n onderdrukte oksidatiewe fosforilasieproses gehad, wat egter deur melatonienbehandeling verbeter is. Melatonien in vitro het insuliengestimuleerde glukoseopname deur kardiomiosiete van jong, maar nie vetsugtige rotte nie, verhoog. In vivo melatonientoediening vir 6 weke het egter basale (in die dieetgroep) en insuliengestimuleerde glukoseopname in beide kontrole- en vetsuggroepe verhoog. Toediening van melatonien in vitro aan mikrovaskulêre endoteelselkulture het ‘n beduidende afname in nekrose, apoptose, stikstofoksied- beskikbaarheid en eNOS aktivering teweeggebring, tesame met ‘n verhoogde aktivering van PKB/Akt, p38MAPK en AMPK. Die nadelige effekte van TNF- toediening op seintransduksie in die mikrovaskulêre endoteelselle is deur melatonien voorkom. Gevogtrekkings: Die resultate toon dat melatonien ‘n merkwaardige beskermende effek op die toename in vatbaarheid vir iskemiese beskadiging in vetsugtige rotte gehad het. Dit mag ook miokardiale glukose-homeostase en mitochondriale oksidatiewe funksie in insulienweerstandigheid verbeter. Melatonien in vitro beskerm mikrovaskulêre endoteelselle teen nekrose asook apoptose en verminder die beskikbaarheid van stikstofoksied. Hierdie voordelige effekte van melatonien mag aan sy anti-oksidantvermoëns of stimulasie van die melatonienreseptor toegeskryf word, maar bewyse daarvoor ontbreek nog. / Division of Medical Physiology (Stellenbosch University), / National Research Foundation / Harry Crossley Foundation

<p>S obzirom na visoku prevalencu metaboličkog sindroma (10-40% u svetskoj populaciji) i na činjenicu da prisustvo metaboličkog sindroma duplira rizik od nastanka aterosklerotske bolesti kardiovaskularnog sistema jasna je potreba za identifikacijom indivudualnih parametara koji doprinose njenom razvoju. Metabolički sindrom je klaster faktora rizika metaboličkog porekla koji je udružen sa povećanim rizikom za nastanak aterosklerotske bolesti kardiovaskularnog sistema i dijabetes melitusa tipa 2. Insulinska rezistencija, abdominalna gojaznost, aterogena dislipidemija, hipertenzija, proinflamatorno i protrombotično stanje su faktori koji su u osnovi metaboličkog sindroma a često su i praćeni nagomilavanjem masti u jetri. Cilj rada je bio da se utvrdi odnos između markera disfunkcije hepatocita (AST, ALT, GGT), serumskog nivoa inflamatornih biomarkera (broj leukocita, elektroforeza serumskih proteina, CRP, fibrinogen, TNF-&alpha;), biomarkera endotelne disfunkcije (ADMA i homocistein), kao i nivoa serumskih adipokina (leptin i adiponektin) i debljine intima-medija kompleksa (IMT) karotidne arterije kao pokazatelja prisustva aterosklerotskog procesa. Ispitivanje je dizajnirano kao studija preseka. U ispitivanje je uključeno 58 ispitanika oba pola sa karakteristikama metaboličkom sindroma (NCEP:ATP III kriterijumi). Odabir ispitanika je vr&scaron;en u Odeljenju za pravilnu ishranu i zdravstvenu bezbednost hrane, Instituta za javno zdravlje Vojvodine. Kontrolnu grupu su sačinjavale 30 klinički i biohemijski zdravih ispitanika nepu&scaron;ača koji su prema polnoj i dobnoj strukturi odgovarali ispitivanim grupama bolesnika. Iz ispitivanja su isključene osobe koje konzumiraju vi&scaron;e od 20g/dan alkohola, pu&scaron;ači, koji imaju dijagnostikovan virusni hepatitis B ili C ili pozitivan Hbs antigen, anti-Hbs antitela i anti-HCV antitela, osobe koje imaju verifikovana oboljenja kardiovaskularnog sistema, bubrega, CNS-a, infektivna, maligna i autoimuna oboljenja kao i druga oboljenja jetre i žučnih puteva, osobe koje su pod medikamentoznom terapijom koja može uticati na nivo serumskih biomarkera endotelne disfunckije, lipidni i lipoproteinski status, glikoregulaciju kao i menstruacioni ciklus. Sve laboratorijske analize su urađene u Centru za laboratorijsku medicinu, Kliničkog centra Vojvodine. Doppler ultrasonografski pregled karotidnih arterija i ultrazvuk abdomena i jetre je urađen u Centru za radiologiju Kliničkog centra Vojvodine. Signifikantna pozitivna korelacija niskog stepena je utvrđena između IMT zajedničke karotidne arterije i serumskih koncentracija GGT, hsCRP i leptina kao i odnosa neutrofili/limfociti. Prema prvom konstruisanom regresionom modelu u kojem je zavisna varijabla bila IMT preko 0,09 cm statistički značajan uticaj na predviđanje debljine IMT zajedničke karotidne arterije imaju hsCRP (Exp (B) 1,112 i glikemija (Exp (B) 1,973). Prema modelu neuronske mreže sa istom zavisnom varijablom najveću mogućnost predviđanja IMT imaju glikemija, AST i fibrinogen. Prema drugom konstruisanom regresionom modelu gde su zavisne varijable bile IMT zajedničke karotidne arterije preko 0,09 cm i prisutnost hepatične steatoze najveću mogućnost predviđanja imaju leptin Exp (B) 1,1022 i ALT Exp (B) 1,053. Prema modelu neuronske mreže sa istom zavisnom varijablom najveću mogućnost predviđanja IMT imaju ALT, ADMA i leptin.</p> / <p>Given the high prevalence of metabolic syndrome (10-40% in the world population) and the fact that the presence of metabolic syndrome doubles the risk of atherosclerotic disease of the cardiovascular system, there is a clear need to identify individual parameters that contribute to its development. Metabolic syndrome is a cluster of the risk factors of metabolic origin that is associated with an increased risk for the onset of atherosclerotic disease of the cardiovascular system and type 2 diabetes mellitus. Insulin resistance, abdominal obesity, atherogenic dyslipidemia, hypertension, proinflammatory and prothrombotic conditions are the factors at the base of the metabolic syndrome and are often accompanied by fat accumulation in the liver. The aim of this work was to determine the relation between markers of hepatic dysfunction (AST, ALT and GGT), serum levels of inflammatory biomarkers (white blood cell count, electrophoresis of serum proteins, CRP, fibrinogen, TNF-&alpha;), biomarkers of endothelial dysfunction (ADMA and homocysteine) as well as levels of serum adipokines (leptin and adiponectin) and intima-media thickness of carotid artery as indicators of atherosclerotic process in the patients with metabolic syndrome. Study was cross-sectional. It included 58 participants with metabolic syndrome (NCEP:ATP III criteria) as well as 30 clinically and biochemically healthy nonsmokers, age and gender matched controls. Participants were selected in the Department for Nutrition and Food Safety, Center of Hygiene and Human Ecology Institute of Public Health of Vojvodina. Patients that consumed alcohol more than 20g/day were excluded. Participants with positive HBsAg, anti-HBs-antibodies or anti- HCV antibodies were excluded also. Smokers were also excluded. Patients with cardiovascular diseases, renal diseases, infective, hepatic, malignant and autoimmune diseases were excluded from this study. Subjects which used drugs that could affect biomarker levels of endothelial dysfunction, lipid metabolism, glucose metabolism and menstrual cycle were also excluded. All laboratory analyzes were done in Centre for Laboratory Medicine, Clinical Centre of Vojvodina. Doppler ultrasonography of carotid arteries and ultrasound of abdomen and liver were done in Centre for Radiology, Clinical Centre of Vojvodina. Significant positive correlation of low degree was determined between IMT of common carotid artery and serum concentrations between GGT, hsCRP and leptin and relationship neutrophils/lymphocytes. According to the first constructed regression model where dependent variable was IMT of common carotid artery above 0.09 cm statistically significant influence on foreseeing IMT of common carotid artery have hsCRP (Exp (B) 1.112 and glycaemia (Exp (B) 1.973). According to the neuronal network with the same dependent variable greatest probability for foreseeing IMT have glycaemia, AST and fibrinogen. According to the second constructed regression model where dependent variable was IMT above 0.09 cm and present hepatic steatosis greatest probability for foreseeing IMT have leptin Exp (B) 1.1022 and ALT Exp (B) 1.053. According to the neuronal network with the same dependent variable greatest probability for foreseeing IMT have ALT, ADMA and leptin.</p>