No description available.

Resveratrol (RSV) is a natural compound that improves mitochondrial function and metabolic health in animal models. Thus far, RSV’s effects on metabolic outcomes in humans are controversial, and RSV’s acute mechanism has not yet been confirmed in vivo. This study aimed to evaluate the effect of an acute dose of RSV on insulin sensitivity and fatty acid oxidation, and to determine RSV’s mechanism of action in human skeletal muscle and adipose tissue. Overweight males (n=8; BMI, 30.5±3.6; VO2peak, 34.0±7.3 ml/kg) reported to the lab on 2 occasions and were provided a breakfast supplemented with 0.3g of RSV or a placebo pill. Experiments were performed in random order using a double blind crossover design. Gas exchange measures, blood samples, and skeletal muscle and adipose tissue biopsies were obtained before and 2 hours after the supplement meal. RSV acutely improved insulin sensitivity, but had no effect on fatty acid oxidation. Additionally, RSV supplementation had no effect on the intracellular signaling of key proteins proposed to mediate its effects in skeletal muscle and adipose tissue. Taken together, these results suggest a single dose of RSV can acutely enhance insulin sensitivity, but its mechanism of action is not conserved across species, and its intracellular signaling pathway is different in humans than previously thought. Due to its insulin sensitizing effect, RSV retains its clinical value, but further research is required to determine its most useful application for human metabolic health. / Thesis (Master, Kinesiology & Health Studies) -- Queen's University, 2013-06-06 13:30:03.522

Metabolic cycles are a fundamental element of cellular and organismal function. Among the most critical in higher organisms is the Cori Cycle, the systemic cycling between lactate and glucose. Here, skeletal muscle-specific Mitochondrial Pyruvate Carrier (MPC) deletion in mice increased muscle glucose uptake but diverted pyruvate into the circulation as lactate, driving increased Cori Cycling and energy expenditure. Loss of muscle MPC activity evoked adaptive glutaminolysis, increased fatty acid oxidation, and resulted in a striking resistance to gains in fat mass with age with perfect sparing of muscle mass and strength. Furthermore, chronic and acute muscle MPC deletion accelerated fat mass loss on a normal diet after high fat diet-induced obesity. Our results illuminate the role of the skeletal muscle MPC as a central node for whole-body carbohydrate, fat, and amino acid metabolism. They highlight the potential utility of decreasing muscle pyruvate oxidation to ameliorate obesity and type 2 diabetes.

The ability to adapt fuel usage to nutrient availability is termed metabolic flexibility, and is influenced by activity of the pyruvate dehydrogenase complex (PDC). The Virginia lines of chickens are a unique model of anorexia and obesity that have resulted from 56 generations of artificial selection for high (HWS) or low (LWS) juvenile body weight. We hypothesized that hyperphagia and obesity in juvenile HWS chickens are associated with altered fatty acid oxidation efficiency and metabolic flexibility in tissues associated with energy sensing and storage, and relative cellular hypertrophy in white adipose tissue. Hypothalamus, liver, Pectoralis major, gastrocnemius, abdominal fat, clavicular fat and subcutaneous fat were collected from juvenile (56-65 day-old) HWS and LWS chickens for metabolic, gene expression and histological assays. The HWS chickens had reduced fatty acid oxidation efficiency in abdominal fat (P < 0.0001) and reduced rates of oxidation in abdominal fat and gastrocnemius (P < 0.0001) as compared to LWS. There was reduced citrate synthase activity in white adipose tissue (P < 0.0001) and greater metabolic inflexibility in skeletal muscle (P = 0.006) of HWS compared to LWS. Greater pyruvate dehydrogenase kinase 4 (PDK4) and forkhead box O1 (FoxO1) mRNA were found in skeletal muscle and white adipose tissue of 56-day-old HWS than LWS. Expression of peroxisome proliferator-activated receptor γ (PPARγ) in all adipose tissue depots was greater (P < 0.05) in LWS than in HWS chickens. The HWS chickens had larger (P < 0.0001) and fewer (P < 0.0001) adipocytes per unit area than LWS. These results suggest that the HWS chickens have impaired metabolic flexibility and fatty acid oxidation efficiency due to an up-regulation of pyruvate dehydrogenase activity to accommodate the influx of acetyl CoA from fatty acid oxidation in skeletal muscle and white adipose tissue. These metabolic adaptations can be linked to differences in gene expression regulation and body composition between the lines. Adipocyte cellularity data are consistent with greater oxidative efficiency in the adipose tissue of LWS, because of the greater number of unfilled cells in all depots that were sampled. Results can be extrapolated to agricultural production in the understanding of factors regulating the amount of lipid deposition in chicken carcass fat. Results may also provide insight into eating disorders and the development of obesity. / Master of Science

No description available.

Mitochondrial fatty acid �-oxidation disorders are a group of clinically and biochemically heterogeneous defects mainly associated with intolerance to catabolic stress. The diseases are potentially fatal, but treatable and the prognosis for most diagnosed disorders is generally favourable. Early diagnosis is thus important to prevent morbidity and mortality. This project describes an improved and validated quantitative fibroblast acylcarnitine profile assay for the investigation of suspected fatty acid �-oxidation disorders. Intact cells were incubated with deuterium-labelled hexadecanoate and L-carnitine, and the accumulated acylcarnitines in the medium analysed using electrospray tandem mass spectrometry. This modified procedure is less demanding technically, requires fewer cells and better reflects the in vivo acylcarnitine status than previously published methods. Mitochondrial fatty acid �-oxidation is coupled to the respiratory chain. Functional defects of one pathway may lead to secondary alterations in flux through the other. The diagnostic specificity and the prognostic potential of the in vitro acylcarnitine profile assay were investigated in fibroblasts from 14 normal controls, 38 patients with eight enzyme deficiencies of fatty acid �-oxidation presenting with various phenotypes, and 16 patients with primary respiratory chain defects including both isolated and multiple enzyme complex defects. All fatty acid �-oxidation deficient cell lines revealed disease-specific acylcarnitine profiles related to the sites of defects irrespective of the severity of symptoms or of different mutation. Preliminary studies suggested a correlation between severity of symptoms and higher concentrations of long-chain acylcarnitine species. However, the fibroblast acylcarnitine profiles from some patients with respiratory chain defects were similar to those of controls, whereas others had abnormal profiles resembling those found in fatty acid �-oxidation disorders. In vitro acylcarnitine profiling is useful for the detection of fatty acid �-oxidation deficiencies, and perhaps the prediction of disease severity and prognostic evaluation facilitating decisions of therapeutic intervention and genetic counselling. However, abnormal profiles do not exclusively indicate these disorders, and primary defects of the respiratory chain remain a possibility. Awareness of this diagnostic pitfall will aid in the selection of subsequent confirmatory tests and therapeutic options.

Šiame darbe siekta išsiaiškinti riebalų rūgščių vaidmenį reguliuojant oksidacinį fosforilinimą saponinu permeabilizuotose žiurkės širdies raumens skaidulose. Pagrindiniai darbo uždaviniai: 1).Įvertinti įvairios struktūros riebalų rūgščių vaidmenį reguliuojant oksidacinį fosforilinimą saponinu permeabilizuotose žiurkės širdies raumens skaidulose;2) Naudojant egzogeninę ADP-suvartojančią piruvato kinazės ir fosfoenolpiruvato sistemą įvertinti, ar oksiduojantis riebalų rūgštims kinta išorinės mitochondrijų membranos laidumas ADP-ui; 3) Tirti, ar riebalų rūgščių oksidacija veikia funkcinę sąveiką tarp kreatino kinazės ir ADP/ATP nešiklio; 4).Nustatyti riebalų rūgščių oksidacijos poveikį mitochondrijų in situ morfologijai bei įvertinti dekstrano T70 poveikį mitochondrijų in situ kvėpavimo parametrams ir morfologijai. Mitochondrijose in situ oksiduojantis įvairios struktūros riebalų rūgštims, vienoms ar mišinyje su piruvatu+malatu, oksidacinio fosforilinimo tariamoji KmADP sumažėja panašiu laipsniu lyginant su piruvato+malato oksidacija. Šis poveikis yra grįžtamas, t.y. riebalų rūgščių oksidacija nedaro įtakos po jos vykstančiai neriebalinės kilmės substratų oksidacijai. Oksiduojantis riebalų rūgštims išsaugoma funkcinė sąveika tarp kreatino kinazės ir ANT, nepaisant ženklaus tar. KmADP reikšmės sumažėjimo. Elektroninės mikroskopijos metodu įvertinome, kad riebalų rūgščių sąlygotas KmADP sumažėjimas gali būti susijęs su mitochondrijų struktūros pokyčiais, kuriuos sukelia riebalų... [to full text] / The aim of this study was to investigate the influence of fatty acid oxidation on the regulation of oxidative phosphorylation in permeabilized rat cardiac fibers. The objectives of the study:1). To evaluate the influence of different fatty acids in the regulation of oxidative phosphorylation in fibers; 2). To evaluate the changes in outer mitochondrial membrane permeability for ADP during fatty acid oxidation by the means of exogenous ADP consuming system consisting of pyruvate kinase and phosphoenolpyruvate;3); To investigate the effect of fatty acid oxidation on the functional coupling between mitochondrial creatine kinase and adenine nucleotide translocase; 4). To investigate the effects of fatty acid oxidation and dextran T70 on the morphology and respiration of mitochondria in saponin-permeabilized rat cardiac fibers. The apparent Km of oxidative phosphorylation for ADP in saponin-permeabilized rat cardiac fibers is decreased several fold during oxidation of fatty acids alone or in the mixture with pyruvate compared to oxidation of pyruvate+malate. This effect is reversible, and fatty acid oxidation does not influence the subsequent oxidation of non-fatty substrates. The functional coupling between creatine kinase and adenine nucleotide translocase is not influenced by fatty acid oxidation and the efficiency of creatine kinase system does not depend on the nature of respiratory substrates. Analysis of electron microscopy images of fibres indicates that morphological... [to full text]

No description available.

Mitochondrial fatty acid �-oxidation disorders are a group of clinically and biochemically heterogeneous defects mainly associated with intolerance to catabolic stress. The diseases are potentially fatal, but treatable and the prognosis for most diagnosed disorders is generally favourable. Early diagnosis is thus important to prevent morbidity and mortality. This project describes an improved and validated quantitative fibroblast acylcarnitine profile assay for the investigation of suspected fatty acid �-oxidation disorders. Intact cells were incubated with deuterium-labelled hexadecanoate and L-carnitine, and the accumulated acylcarnitines in the medium analysed using electrospray tandem mass spectrometry. This modified procedure is less demanding technically, requires fewer cells and better reflects the in vivo acylcarnitine status than previously published methods. Mitochondrial fatty acid �-oxidation is coupled to the respiratory chain. Functional defects of one pathway may lead to secondary alterations in flux through the other. The diagnostic specificity and the prognostic potential of the in vitro acylcarnitine profile assay were investigated in fibroblasts from 14 normal controls, 38 patients with eight enzyme deficiencies of fatty acid �-oxidation presenting with various phenotypes, and 16 patients with primary respiratory chain defects including both isolated and multiple enzyme complex defects. All fatty acid �-oxidation deficient cell lines revealed disease-specific acylcarnitine profiles related to the sites of defects irrespective of the severity of symptoms or of different mutation. Preliminary studies suggested a correlation between severity of symptoms and higher concentrations of long-chain acylcarnitine species. However, the fibroblast acylcarnitine profiles from some patients with respiratory chain defects were similar to those of controls, whereas others had abnormal profiles resembling those found in fatty acid �-oxidation disorders. In vitro acylcarnitine profiling is useful for the detection of fatty acid �-oxidation deficiencies, and perhaps the prediction of disease severity and prognostic evaluation facilitating decisions of therapeutic intervention and genetic counselling. However, abnormal profiles do not exclusively indicate these disorders, and primary defects of the respiratory chain remain a possibility. Awareness of this diagnostic pitfall will aid in the selection of subsequent confirmatory tests and therapeutic options.

By facilitating timely diagnosis and treatment initiation, population-wide newborn screening programs have led to important reductions in morbidity and mortality for many rare diseases, including medium-chain acyl-CoA dehydrogenase (MCAD) deficiency and very-long-chain acyl-CoA dehydrogenase (VLCAD) deficiency. Newborn screening has also expanded the spectrum of disease severity for MCAD and VLCAD deficiencies to include a higher proportion of milder cases, raising questions about appropriate disease management. To date there has been no systematic attempt to characterize best management practices in terms of the guidance that is available to those who provide care for MCAD and VCLAD deficiencies; nor has there been an attempt to understand the extent to which current practices align with such currently available guidance. The two projects that are part of this thesis sought to address these research gaps with a particular focus on two key disease-specific management practices we identified in advance as priorities: the use of carnitine supplementation and the recommended duration of fasting. The objective of the first project was to systematically review the quality and content of clinical practice guidelines and/or recommendations for the diagnosis and management of both MCAD and VLCAD deficiencies. Two independent reviewers assessed the eligibility of citations retrieved from a comprehensive search of the peer-reviewed and grey literature. We appraised the quality of the reviewed guidance and extracted information on the content of recommendations. From the 25 guidance documents that met our inclusion criteria, only 7 incorporated evidence reviews, indicating that guidance in this field does not generally meet established methodological standards for the rigorous development of clinical practice guidelines. With respect to content, we identified unclear and inconsistent recommendations regarding fasting times and the use of carnitine supplementation. Further empirical evidence in these areas is necessary to inform the development of future rigorous guidelines. The objective of the second project was to identify actual practices in the management of MCAD deficiency. We conducted a scoping review of published literature on treatment practices around the world and a secondary analysis of data documenting treatments received by participants in a Canadian pediatric cohort study. For the scoping review, citations retrieved from our comprehensive search strategy were screened by two independent reviewers. We extracted information on study characteristics and disease management. Our secondary analysis included longitudinal data for Canadian children with MCAD deficiency, born between 2006 and 2015 and enrolled in a cohort study at one of 13 centres. For both project components, we described carnitine supplementation and fasting times, overall and according to potential indicators of disease severity (genotype, biochemical phenotype). We identified 5 relevant publications in the scoping review and analyzed data for 107 children participating in the Canadian cohort. Management practices related to carnitine supplementation and fasting times for MCAD deficiency were highly variable based on both data sources. There was some evidence of an association between genotype and carnitine use, which, based on the scoping review, may be due to a relationship between genotype and carnitine deficiency. While actual practice was in some ways aligned with the guidance we reviewed in the first project, these results underscore the need for further evidence to address areas of uncertainty that have been prioritized by patients and families, clinicians, and health researchers, including questions regarding the potential to tailor treatment to predicted disease severity and an emphasis on controversial therapies such as carnitine supplementation.