Dense Stellar Populations: Initial Conditions

This chapter is based on four lectures given at the Cambridge N-body school "Cambody". The material covered includes the IMF, the 6D structure of dense clusters, residual gas expulsion and the initial binary population. It is aimed at those needing to initialise stellar populations for a variety of purposes (N-body experiments, stellar population synthesis).Comment: 85 pages. To appear in The Cambridge N-body Lectures, Sverre Aarseth, Christopher Tout, Rosemary Mardling (eds), Lecture Notes in Physics Series, Springer Verla

Antioxidant effect of exercise: Exploring the role of the mitochondrial complex I superassembly

Mitochondrial respiratory complexes become assembled into supercomplexes (SC) under physiological conditions. One of the functional roles of these entities is the limitation of reactive oxygen species (ROS) produced by complex I (CI) of the respiratory chain. We sought to determine whether the systemic antioxidant effect of exercise is mediated by the assembly of mitochondrial CIs into SCs in rats. Male Wistar rats were exercise trained or remained sedentary for ten weeks; then, blood samples were collected, and the gastrocnemius muscle was isolated. The assembly of mitochondrial SCs and the lipid peroxidation of the mitochondrial and plasmatic fractions were assessed. Our results demonstrate that exercise induced the assembly of CI into SCs in the gastrocnemius and induced a systemic decrease in lipid peroxidation. We also found an inverse association between the superassembly of CIs and mitochondrial lipid peroxidation (p < 0.01) and protein carbonyls (p < 0.05). We conclude that exercise induces the chronic assembly of CIs into SCs, which provide mitochondrial protection against oxidative damage, at least in the studied muscle. Given the relevant role that mitochondria play in health and disease, these findings should help to elucidate the role of exercise as a therapeutic approach for metabolic diseases

QUERCETIN EFFECTS ON WEIGHT GAIN AND CALORIC INTAKE IN EXERCISED RATS

Quercetin is a flavonoid which activates oxidative metabolism. Quercetin may reduce weight gain by decreasing feed efficiency. The present study aims to evaluate weight gain, caloric intake and feed efficiency in exercised and sedentary rats supplemented with quercetin. Wistar rats were divided into four groups: quercetin-exercise training (QT), quercetin-sedentary (QS), placebo-exercise training (PT) and placebo-sedentary (PS). Rats were exercised and/or orally supplemented with quercetin (25 mg · kg-1 on alternate days) during six weeks. Weight gain of the QT group decreased when compared with the PT and PS groups. Exercised groups increased cumulative caloric intake during the experimental period. The QT group rats also reduced their feed efficiency when compared with the QS and PS groups. These results suggest that quercetin is not able to decrease weight gain because no differences were found between placebo and quercetin condition either in the sedentary or in the training condition

Human muscular mitochondrial fusion in athletes during exercise.

The main objective of this work was to investigate whether mitochondrial fusion occurs in the skeletal muscle of well-trained athletes in response to high-intensity exercise. Well-trained swimmers (n = 9) performed a duration-matched sprint interval training (SIT) and high-intensity high-volume training (HIHVT) session on separate days. Muscle samples from triceps brachii were taken before, immediately after, and 3 h after the training sessions. Transmission electron microscopy (TEM) was applied to assess mitochondrial morphology. Moreover, expression of genes coding for regulators of mitochondrial fusion and fission were assessed by real-time quantitative PCR. In addition, mitofusin (MFN)2 and optic atrophy 1 (OPA1) were quantified by Western blot analysis. TEM analyses showed that mitochondrial morphology remained altered for 3 h after HIHVT, whereas SIT-induced changes were only evident immediately after exercise. Only SIT increased MFN1 and MFN2 mRNA expression, whereas SIT and HIHVT both increased MFN2 protein content 3 h after exercise. Notably, only HIHVT increased OPA1 protein content. Mitochondrial morphologic changes that suggest fusion occurs in well-adapted athletes during exercise. However, HIHVT appears as a more robust inducer of mitochondrial fusion events than SIT. Indeed, SIT induces a rapid and transient change in mitochondrial morphology