The relation of respiratory muscle strength to disease severity and abnormal ventilation during exercise in chronic heart failure patients

Background: Breathlessness is a common problem in chronic heart failure (CHF) patients, and respiratory muscle strength has been proposed to play an important role in causing breathlessness in these patients. Objectives: The aim of this study was to investigate the relation between respiratory muscle strength and the severity of CHF, and the influence of respiratory muscle strength on abnormal ventilation during exercise in CHF patients. Patients and Methods: In this case series study, we assessed clinically stable CHF outpatients (N = 66, age: 57.7 ± 14.6 years). The peak oxygen consumption (peak VO2), the slope relating minute ventilation to carbon dioxide production (VE/VCO2 slope), and the slope relating tidal volume to respiratory rate (TV/RR slope) were measured during cardiopulmonary exercise testing. Respiratory muscle strength was assessed by measuring the maximal inspiratory pressure (MIP) and maximal expiratory pressure (MEP). Results: The MIP and MEP decreased significantly as the New York Heart Association functional class increased (MIP, P = 0.021; MEP, P < 0.01). The MIP correlated with the TV/RR slope (r = 0.57, P < 0.001) and the VE/VCO2 slope (r = -0.44, P < 0.001), and the MEP also correlated with the TV/RR slope (r = 0.53, P < 0.001) and the VE/VCO2 slope (r=-0.25, P < 0.040). Stepwise multiple regression analysis revealed that age and MIP were statistically significant predictors of the TV/RR and VE/VCO2 slopes (both P < 0.05). Conclusions: Respiratory muscle strength is related to the severity of CHF, and associated with rapid and shallow ventilation or excessive ventilation during exercise

Heart-rate response to sympathetic nervous stimulation, exercise, and magnesium concentration in various sleep conditions. Int J Sport Nutr Exerc Metab

The aim of this study was to clarify the mechanism of impaired exercise tolerance in chronic sleep-restricted conditions by investigating variables related to heart-rate (HR) response to sympathetic nervous stimulation. Sixteen healthy men (mean age 21.5 years) were tested in a control state, acute sleep-loss state, and chronic sleeprestricted state. Participants underwent cardiopulmonary exercise testing in each state. Their norepinephrine (NE) concentration was measured before and immediately after exercise. Intracellular magnesium (Mg) concentration was measured in a resting state. Exercise duration was shorter and the ratio of HR response to the percentage increase in NE was higher in the chronic sleep-restricted state than in the control state. Intracellular Mg gradually decreased from control to chronic sleep restriction. There was a negative correlation between peak exercise duration and the ratios of HR response to the rate of increase in NE. Intracellular Mg was positively correlated with the ratios of HR response to the increase in NE both in control and in acute sleep loss. The authors conclude that the impaired exercise tolerance in a chronic sleep-restricted state is caused by hypersensitivity of the HR response to sympathetic nervous stimulation, which showed a compensation for decreased intracellular Mg concentration. Keywords: sleep deprivation, sympathetic nervous stimulation, exercise tolerance In the field of competitive sports, athletes always take care of their physical condition, including fatigue or sleep status, and try to control it during training. It is very important to control it because it directly influences their performance. In our previous studies, oxygen uptake (VO 2 ) was decreased during exercise, as indicated by anaerobic threshold (AT) and peak VO 2 , in a state of chronic sleep restriction in young healthy participants The authors are with th

Genes activated by LPS and IFNγ.

a<p>Genes obtained by subtractive cloning are marked “S”.</p

Subtraction efficiency evaluated by cDNA microarray analysis.

<p>An in-house microarray containing cDNA clones derived from the control cells (gray bars, 97 spots in total), LPS/IFNγ-stimulated cells (white bars, 105 spots), and subtracted products (black bars, 124 spots) was prepared, and analyzed for changes in the mRNA levels in response to LPS and IFNγ. The percentages of the clones that had altered mRNA levels indicated in the horizontal axis are plotted for each clone group.</p

Monitoring subtraction processes.

<p>PCR-amplified cDNA mixtures (0.2 µg) derived from the control cells (C), cells stimulated by LPS and IFNγ (L/I), first-round subtracted products (S1), and second-round subtracted products (S2) were electrophoresed, stained (top panel), and subjected to Southern analysis to detect the cDNAs of interferon gamma inducible protein 47 (IFI47) and glyceraldehyde-3-phosphate dehydrogenase (GAPDH).</p