Energy balance and lipoprotein metabolism

High triglyceride concentration (TG) is associated with an increased risk for cardiovascular disease. Thus, lifestyle interventions that reduce, or prevent an increase, in plasma TG concentration, such as exercise and diet, can help in the prevention of cardiovascular disease. These interventions enclose changes on energy balance (EB) and particularly changes in energy expenditure, achieved through exercise, and energy intake accomplished through changing the total food intake. The present thesis investigated the effect of acute alterations of the energy balance on very low density lipoprotein- TG metabolism (VLDL-TG). To this end, VLDL-TG kinetics were determined using stable isotope tracer methodology, in the postabsorptive state after exercise and diet interventions (hepatic secretion and plasma clearance rate of VLDL-TG were estimated). More specifically,we studied the acute and delayed effects of a high intensity aerobic exercise session (60% and 90% of maximal oxygen consumption (VO2peak) for ~ 1/2h, EB:-2MJ) on VLDL-TG metabolism in healthy men (1st research study). Also, we evaluated the effects of equivalent energy deficits induced by exercise (60% VO2peak for ~ 2h, EB:-2MJ) or calorie restriction (EB:-2MJ) on VLDL-TG metabolism in women (2nd research study). Finally, we studied the effects the effects of acute negative (EB:-3MJ) and positive energy balance (EB: +3 MJ) on VLDL-TG metabolism in healthy women (3rd research study).Η υψηλή συγκέντρωση τριγλυκεριδίων (TG) σχετίζεται με αυξημένο κίνδυνο για την εμφάνιση καρδιαγγειακών νοσημάτων. Συνεπώς, παρεμβάσεις στον τρόπο ζωής που μειώνουν ή εμποδίζουν την αύξηση της συγκέντρωσης των TG στο πλάσμα, όπως η άσκηση και η δίαιτα, μπορούν να βοηθήσουν στην πρόληψη εμφάνισης καρδιαγγειακής νόσου. Οι παρεμβάσεις αυτές ουσιαστικά εσωκλείουν μεταβολές και επιδράσεις στο ενεργειακό ισοζύγιο (ΕΙ) και συγκεκριμένα μεταβολές στην ενεργειακή δαπάνη, που επιτυγχάνονται μέσω της άσκησης, και στην ενεργειακή πρόσληψη μέσω της τροφής που καταναλώνεται. Η παρούσα διατριβή διερεύνησε την επίδραση οξέων μεταβολών του ενεργειακού ισοζυγίου στο μεταβολισμό των TG των λιποπρωτεϊνών πολύ χαμηλής πυκνότητας (VLDL-TG). Για το σκοπό αυτό, προσδιορίστηκε η κινητική των VLDL-TG με χρήση σταθερών ισοτόπων ιχνηθέτησης γλυκερόλης, στο μεταπορροφητικό στάδιο (εκτιμήθηκε ο ρυθμός ηπατικής έκκρισης και ο ρυθμός πλασματικής εκκαθάρισης των VLDL-TG) μετά από παρεμβάσεις στο ενεργειακό ισοζύγιο. Συγκεκριμένα, μελετήθηκε η οξεία και καθυστερημένη επίδραση μιας συνεδρίας αερόβιας άσκησης υψηλής έντασης (εναλλασσόμενη ένταση ίση με 60% και 90% της μέγιστης πρόσληψης οξυγόνου (VO2peak) για ~1/2h, ΕΙ:-2MJ) στον μεταβολισμό των VLDL-TG σε υγιείς άνδρες (1η Ερευνητική μελέτη). Επίσης, αξιολογήθηκαν οι επιδράσεις μιας συνεδρίας άσκησης μέτριας έντασης (60% VO2peak για ~2h, ΕΙ:-2MJ) και της μείωσης της ενεργειακής πρόσληψης (ΕΙ:-2MJ) στον μεταβολισμό των VLDL-TG σε υγιείς γυναίκες (2η Ερευνητική μελέτη). Τέλος, μελετήθηκαν οι επιδράσεις της οξείας μείωσης (ΕΙ:-3MJ) και οξείας αύξησης (ΕΙ:+3MJ) της ενεργειακής πρόσληψης στον μεταβολισμό των VLDL-TG σε υγιείς γυναίκες (3η Ερευνητική μελέτη)

Effect of acute negative and positive energy balance on basal very-low density lipoprotein triglyceride metabolism in women.

BACKGROUND: Acute reduction in dietary energy intake reduces very low-density lipoprotein triglyceride (VLDL-TG) concentration. Although chronic dietary energy surplus and obesity are associated with hypertriglyceridemia, the effect of acute overfeeding on VLDL-TG metabolism is not known. OBJECTIVE: The aim of the present study was to investigate the effects of acute negative and positive energy balance on VLDL-TG metabolism in healthy women. DESIGN: Ten healthy women (AGE: 22.0±2.9 years, BMI: 21.2±1.3 kg/m(2)) underwent a stable isotopically labeled tracer infusion study to determine basal VLDL-TG kinetics after performing, in random order, three experimental trials on the previous day: i) isocaloric feeding (control) ii) hypocaloric feeding with a dietary energy restriction of 2.89±0.42 MJ and iii) hypercaloric feeding with a dietary energy surplus of 2.91±0.32 MJ. The three diets had the same macronutrient composition. RESULTS: Fasting plasma VLDL-TG concentrations decreased by ∼26% after hypocaloric feeding relative to the control trial (P = 0.037), owing to decreased hepatic VLDL-TG secretion rate (by 21%, P = 0.023) and increased VLDL-TG plasma clearance rate (by ∼12%, P = 0.016). Hypercaloric feeding increased plasma glucose concentration (P = 0.042) but had no effect on VLDL-TG concentration and kinetics compared to the control trial. CONCLUSION: Acute dietary energy deficit (∼3MJ) leads to hypotriglyceridemia via a combination of decreased hepatic VLDL-TG secretion and increased VLDL-TG clearance. On the other hand, acute dietary energy surplus (∼3MJ) does not affect basal VLDL-TG metabolism but disrupts glucose homeostasis in healthy women

Development of 3D Printed Enzymatic Microreactors for Lipase-Catalyzed Reactions in Deep Eutectic Solvent-Based Media

In this study, 3D printing technology was exploited for the development of immobilized enzyme microreactors that could be used for biocatalytic processes in Deep Eutectic Solvent (DES)-based media. 3D-printed polylactic acid (PLA) microwell plates or tubular microfluidic reactors were modified with polyethylenimine (PEI) and lipase from Candida antarctica (CALB) was covalently immobilized in the interior of each structure. DESs were found to have a negligible effect on the activity and stability of CALB, and the system proved highly stable and reusable in the presence of DESs for the hydrolysis of p-nitrophenyl butyrate (p-NPB). A kinetic study under flow conditions revealed an enhancement of substrate accessibility in the presence of Betaine: Glycerol (Bet:Gly) DES, while the system was not severely affected by diffusion limitations. Incubation of microreactors in 100% Bet:Gly preserved the enzyme activity by 53% for 30 days of storage at 60 °C, while the buffer-stored sample had already been deactivated. The microfluidic enzyme reactor was efficiently used for the trans-esterification of ethyl ferulate (EF) with glycerol towards the production of glyceryl ferulate (GF), known for its antioxidant potential. The biocatalytic process under continuous flow conditions exhibited 23 times higher productivity than the batch reaction system. This study featured an effective and robust biocatalytic system with immobilized lipase that can be used both in hydrolytic and synthetic applications, while further optimization is expected to upgrade the microreactor system performance

Association of Anthropometric and Lifestyle Parameters with Fitness Levels in Greek Schoolchildren: Results from the EYZHN Program

ObjectiveThe aim of the study was to evaluate physical fitness (PF) and identify its anthropometric and lifestyle determinants in a sample of Greek schoolchildren.MethodsThe study sample consisted of 335,810 schoolchildren (♂: 51.3%, 6–18 years old). Students’ anthropometric parameters and PF levels—assessed via the Eurofit test battery—were measured by trained physical education teachers and evaluated according to the available norms, while their lifestyle habits were assessed through a questionnaire.ResultsIn all applied PF tests, students’ performance was negatively associated with the presence of obesity and central obesity, defined through international criteria for body mass index and waist to height ratio, respectively. According to multiple logistic regression analysis, the presence of overweight/obesity [odds ratio (OR): 4.43, 95% confidence interval (CI): 3.98–4.93], low adherence to the MD (KIDMED ≤ 3) (OR: 1.27, 95% CI: 1.09–1.48), and increased time spent in sedentary activities (>2 h per day) (OR: 1.16, 95% CI: 1.03–1.29) were positively associated with poor PF, after adjusting for age and sex. In contrast, for every 1 day increase in the weekly frequency of engagement in athletic activity, the probability of poor PF decreased by 26% (OR: 0.74, 95% CI: 0.72–0.77). In a similar model, the presence of central obesity emerged as an even stronger possible predictor of poor PF (OR: 5.20, 95% CI: 4.66–5.78), compared to the presence of general obesity.ConclusionHigher general or abdominal adiposity, as well as the adoption of a low-quality diet and a sedentary lifestyle, is strongly associated with low PF levels during childhood

Baseline characteristics of subjects (n = 10).

<p>Baseline characteristics of subjects (n = 10).</p

Dietary energy intake and macronutrient content of the experimental diets.

<p>Values are means ± SD (n = 10). ^* Significantly different from isocaloric diet, P<0.05. ^† Significantly different from hypercaloric diet, P<0.05.</p

Effectsof hypocaloric or hypercaloric feeding relative to isocaloric feeding on the plasma clearance rate of very low density lipoprotein triglyceride (VLDL-TG).

<p>Data are means ± SD (n = 10). *Significantly different from isocaloric diet, P = 0.016.^† Significantly different from hypercaloric diet, P<0.001.</p