Is a sedentary lifestyle an independent predictor for hospital and early mortality after elective cardiac surgery?

Objective

This study evaluates whether a sedentary lifestyle is an independent predictor for increased mortality after elective cardiac surgery.

Methods

Three thousand one hundred fifty patients undergoing elective cardiac surgery between January 2007 and June 2012 completed preoperatively the Corpus Christi Heart Project questionnaire concerning physical activity (PA). Based on this questionnaire, 1815 patients were classified as active and 1335 patients were classified as sedentary. The endpoints of the study were hospital mortality and early mortality.

Results

The study population had a mean age of 69.7 ± 10.1 (19–95) years and a mean logistic EuroSCORE risk of 5.1 ± 5.6 (0.88–73.8). Sedentary patients were significantly older (p = 0.001), obese (p = 0.001), had a higher EuroSCORE risk (p = 0.001), and a higher percentage of complications. Hospital mortality (1.1 % versus 0.4 % (p = 0.014)) and early mortality (1.5 % versus 0.6 % (p = 0.006)) were significantly higher in the sedentary group compared with the active group. However, a sedentary lifestyle was not identified as an independent predictor for hospital mortality (p = 0.61) or early mortality (p = 0.70).

Conclusion

Sedentary patients were older, obese and had a higher EuroSCORE risk. They had significantly more postoperative complications, higher hospital mortality and early mortality. Despite these results, sedentary behaviour could not be identified as an independent predictor for hospital or early mortality.     

Is peak postprandial oxygen consumption positively related to growth rate and resting oxygen consumption in a sedentary catfish Silurus meridionalis?

The resting oxygen consumption     , postprandial and post-exercise peak oxygen consumption     of 137 juvenile southern catfish Silurus meridionalis , weighing 18·5 ± 0·8 g (mean ± s . d .), were measured at 25° C to determine whether     is positively related to postprandial and post-exercise     in sedentary S. meridionalis . In addition, postprandial metabolic response [ i.e. the specific dynamic action (SDA)] after a satiating meal and the growth performance as a consequence of a 3 week feeding-growth trail were measured in 40 S. meridionalis , weighing 14·3 ± 0·2 g, at 25° C to determine whether postprandial     is positively related to growth rate. Postprandial     was positively correlated with     , while post-exercise     was not. Both postprandial     and post-exercise     were positively correlated with factorial and absolute scope. There was no significant correlation between the growth rate and postprandial     in S. meridionalis . It suggested that as a sit-and-wait forager with low     , low post-exercise     and high postprandial     , the expenditure of energy for maintenance in S. meridionalis may be more closely related to digestive processes than locomotor activities.     

The influence of a 1-year programme of brisk walking on endurance fitness and body composition in previously sedentary men aged 42–59 years

This study examined the influence of a 1-year brisk walking programme on endurance fitness and the amount and distribution of body fat in a group of formerly sedentary men. Seventy-two males, aged 42–59 years, body mass index 25.2 (0.3) kg·m^–2 [mean (SEM)], were randomly allocated to either a walking group (n = 48) or control group (n = 24). Brisk walking speed was evaluated using a 1.6-km track walk. Changes in endurance fitness were assessed by measuring blood lactate concentration and heart rate during submaximal treadmill walking. Body composition was determined by hydrostatic weighing and anthropometry; energy intake was assessed from 7-day weighed food inventories. Differences in the response of walkers and controls were examined using two-way analyses of variance. Forty-two walkers (87.5%) completed the study and averaged 27.9 (1.4) min·day^–1 of brisk walking (range 11–46). Brisk walking speed averaged 1.95 (0.03) m·s^–1 and elicited approximately 68 (1) % of maximum heart rate. Heart rate and blood lactate concentration during submaximal treadmill walking were significantly reduced in the walkers after 3, 6 and 12 months and the oxygen uptake at a reference blood lactate concentration of 2 mmol·l^–1 was increased by 3.2 ml·kg^–1. min^–1 (14.9%) in the walkers at 6 months (P< 0.01). Although skinfold thicknesses at anterior thigh and medial calf sites decreased significantly for the walkers, the response of the two groups did not differ significantly for other body composition variables or for energy intake.     

Untargeted metabolomics analysis of ischemia–reperfusion-injured hearts ex vivo from sedentary and exercise-trained rats

Introduction

The effects of exercise on the heart and its resistance to disease are well-documented. Recent studies have identified that exercise-induced resistance to arrhythmia is due to the preservation of mitochondrial membrane potential.

Objectives

To identify novel metabolic changes that occur parallel to these mitochondrial alterations, we performed non-targeted metabolomics analysis on hearts from sedentary and exercise-trained rats challenged with isolated heart ischemia–reperfusion injury (I/R).

Methods

Eight-week old Sprague–Dawley rats were treadmill trained 5 days/week for 6 weeks (exercise duration and intensity progressively increased to 1 h at 30 m/min up a 10.5% incline, 75–80% VO_2max). The recovery of pre-ischemic function for sedentary rat hearts was 28.8?±?5.4% (N?=?12) compared to exercise trained hearts, which recovered 51.9%?±?5.7 (N?=?14) (p?<?0.001).

Results

Non-targeted GC–MS metabolomics analysis of (1) sedentary rat hearts; (2) exercise-trained rat hearts; (3) sedentary rat hearts challenged with global ischemia–reperfusion (I/R) injury; and (4) exercise-trained rat hearts challenged with global I/R (10/group) revealed 15 statistically significant metabolites between groups by ANOVA using Metaboanalyst (p?<?0.001). Enrichment analysis of these metabolites for pathway-associated metabolic sets indicated a?>?10-fold enrichment for ammonia recycling and protein biosynthesis. Subsequent comparison of the sedentary hearts post-I/R and exercise-trained hearts post-I/R further identified significant differences in three metabolites (oleic acid, pantothenic acid, and campesterol) related to pantothenate and CoA biosynthesis (p?≤?1.24E?05, FDR?≤?5.07E?4).

Conclusions

These studies shed light on novel mechanisms in which exercise-induced cardioprotection occurs in I/R that complement both the mitochondrial stabilization and antioxidant mechanisms recently described. These findings also link protein synthesis and protein degradation (protein quality control mechanisms) with exercise-linked cardioprotection and mitochondrial susceptibility for the first time in cardiac I/R.

     

Interactions ofMonoporeia affinis (Lindström) (Amphipoda) with sedentary Chironomidae

Interannual population oscillations ofMonoporeia affinis and sedentary chironomids are negatively correlated in Lake Mälaren. Sedentary chironomid abundance regressed againstM. affinis density was highly significant at a lag response of one year (adj. R²=0.54, P=0.0001). The inverse correlation between Tanytarsini (Micropsectra sp. andTanytarsus sp.) andM. affinis densities supports a recruitment limitation hypothesis,viz. that the growth or survival of early instar chironomids is low at high amphipod densities. Microcosm studies showed density-dependent effects on the growth and survival of second instarCh. riparius larvae across an amphipod density gradient. No significant effects were found on growth or survival of third instars. These findings support the chironomid recruitment limitation hypothesis. Amphipod predation on early instar chironomid larvae is suggested as a population controlling mechanism.     

Different times of day do not change heart rate variability recovery after light exercise in sedentary subjects: 24 hours Holter monitoring

Incidence of cardiovascular events follows a circadian rhythm with peak occurrence during morning. Disturbance of autonomic control caused by exercise had raised the question of the safety in morning exercise and its recovery. Furthermore, we sought to investigate whether light aerobic exercise performed at night would increase HR and decrease HRV during sleep. Therefore, the aim of this study was to test the hypothesis that morning exercise would delay HR and HRV recovery after light aerobic exercise, additionally, we tested the impact of late night light aerobic exercise on HR and HRV during sleep in sedentary subjects. Nine sedentary healthy men (age 24 ± 3 yr; height 180 ± 5 cm; weight 79 ± 8 kg; fat 12 ± 3%; mean±SD) performed 35 min of cycling exercise, at an intensity of first anaerobic threshold, at three times of day (7 a.m., 2 p.m. and 11 p.m.). R-R intervals were recorded during exercise and during short-time (60 min) and long-time recovery (24 hours) after cycling exercise. Exercise evoked increase in HR and decrease in HRV, and different times of day did not change the magnitude (p < 0.05 for time). Morning exercise did not delay exercise recovery, HR was similar to rest after 15 minutes recovery and HRV was similar to rest after 30 minutes recovery at morning, afternoon, and night. Low frequency power (LF) in normalized unites (n.u.) decreased during recovery when compared to exercise, but was still above resting values after 60 minutes of recovery. High frequency power (HF-n.u.) increased after exercise cessation (p < 0.05 for time) and was still below resting values after 60 minutes of recovery. The LF/HF ratio decreased after exercise cessation (p < 0.05 for time), but was still different to baseline levels after 60 minutes of recovery. In conclusion, morning exercise did not delay HR and HRV recovery after light aerobic cycling exercise in sedentary subjects. Additionally, exercise performed in the night did change autonomic control during the sleep. So, it seems that sedentary subjects can engage physical activity at any time of day without higher risk.     

Can a reductionist be a pluralist?

Pluralism is often put forth as a counter-position to reductionism. In this essay, I argue that reductionism and pluralism are in fact consistent. I propose that there are several potential goals for reductions and that the proper form of a reduction should be considered in tandem with the goal that it aims to achieve. This insight provides a basis for clarifying what version(s) of reductionism are currently defended, for explicating the notion of a fundamental level of explanation, and for showing how one can be both a reductionist and a pluralist.     

When is a parasite species a species?

Regrettably, 140 years after the publication of Darwin's Origin of Species, we face the grotesque situation that we still do not know what is a species whose origin Darwin wanted to explain. A generally applicable species definition is not available. Is there a basic unit of biodiversity above the level of individuals? Do we try to define something that does not exist in reality? The strong potential for the evolution of genetic variability in parasites together with the importance of species diagnosis for applied fields of parasite research make biodiversity research a key role in parasitology. Frequent occurrence of sympatric speciation, clonal reproduction, selfing, sib mating or parthenogenesis imply exceptional conditions for the evolution of gene pool diversities in parasites.     

When is a peroxisome not a peroxisome?

It is time to drop the glyoxysome name. Recent functional genomics analysis together with cell biology studies emphasize the unifying features of peroxisomes rather than their differences. Plant peroxisomes contain 300 or more proteins, the functions of which are dominated by activities related to fatty acid oxidation (>70 enzymes). By comparison, relatively few proteins are committed to metabolism of reactive oxygen species ( approximately 20) and to photorespiration ( approximately 10). Analysis of triglyceride metabolism in Arabidopsis seedlings now indicates that only two enzymes (isocitrate lyase and malate synthase) potentially distinguish glyoxysomes from other peroxisomes. Future research is best served by focusing on the common features of peroxisomes to establish how these dynamic organelles contribute to energy metabolism, development and responses to environmental challenges.     

Between a rock and a hard place?

Developing small-molecule inhibitors against protein-protein interaction targets is among the most difficult challenges in contemporary drug discovery. Recent developments in our understanding of this problem, and in the knowledge and tools available to address it, give cause for renewed hope, but substantial challenges remain.