Validation of the Actiheart activity monitor for measurement of activity energy expenditure in children and adolescents with chronic disease.

BACKGROUND/OBJECTIVES: The purpose of this study was to develop an activity energy expenditure (AEE) prediction equation for the Actiheart activity monitor for use in children with chronic disease. SUBJECTS/METHODS: In total, 63 children, aged 8-18 years with different types of chronic disease (juvenile arthritis, hemophilia, dermatomyositis, neuromuscular disease, cystic fibrosis or congenital heart disease) participated in an activity testing session, which consisted of a resting protocol, working on the computer, sweeping, hallway walking, steps and treadmill walking at three different speeds. During all activities, actual AEE was measured with indirect calorimetry and the participants wore an Actiheart on the chest. Resting EE and resting heart rate were measured during the resting protocol and heart rate above sleep (HRaS) was calculated. RESULTS: Mixed linear modeling produced the following prediction equation: This equation results in a nonsignificant mean difference of 2.1 J/kg/min (limits of agreement: -144.2 to 148.4 J/kg/min) for the prediction of AEE from the Actiheart compared with actual AEE. CONCLUSIONS: The Actiheart is valid for the use of AEE determination when using the new prediction equation for groups of children with chronic disease. However, the prediction error limits the use of the equation in individual subjects.

Creatine monohydrate enhances strength and body composition in Duchenne muscular dystrophy.

OBJECTIVE: To determine whether creatine monohydrate (CrM) supplementation increases strength and fat-free mass (FFM) in boys with Duchenne muscular dystrophy (DD). METHODS: Thirty boys with DD (50% were taking corticosteroids) completed a double-blind, randomized, cross-over trial with 4 months of CrM (about 0.10 g/kg/day), 6-week wash-out, and 4 months of placebo. Measurements were completed of pulmonary function, compound manual muscle and handgrip strength, functional tasks, activity of daily living, body composition, serum creatine kinase and gamma-glutamyl transferase activity and creatinine, urinary markers of myofibrillar protein breakdown (3-methylhistidine), DNA oxidative stress (8-hydroxy-2-deoxyguanosine [8-OH-2-dG]), and bone degradation (N-telopeptides). RESULTS: During the CrM treatment phase, there was an increase in handgrip strength in the dominant hand and FFM (p < 0.05), with a trend toward a loss of global muscle strength (p = 0.056) only for the placebo phase, with no improvements in functional tasks or activities of daily living. Corticosteroid use, but not CrM treatment, was associated with a lower 8-OH-2-dG/creatinine (p < 0.05), and CrM treatment was associated with a reduction in N-telopeptides (p < 0.05). CONCLUSIONS: Four months of CrM supplementation led to increases in FFM and handgrip strength in the dominant hand and a reduction in a marker of bone breakdown and was well tolerated in children with DD.

Results of lung volume reduction surgery in patients with emphysema. The Washington University Emphysema Surgery Group.

Between January 1993 and April 1995, 84 patients with emphysema underwent bilateral lung volume reduction surgery at Barnes Hospital, Fifty-three patients had completed 3 months; 37 patients, 6 months; and 19 patients, 1 year of follow-up. Significant improvement was observed in spirometric parameters, oxygenation, 6-minute walking distance, dyspnea indices, and quality-of-life scores. The average increases in FEV1 were 52%, 51%, and 61%, at 3,6, and 12 months, respectively, after surgery. The most common postoperative complication, prolonged ( > 7 days) chest tube drainage, was present in 63% of the cases, and the mean duration of hospitalization in the survivors was 15 days (range 5 to 49 days). This has been reduced to 11 days (median 7.5 days) for the subsequent 40 patients. Five postoperative deaths occurred, 2 in the first, 2 in the third, and 1 in the fifth postoperative month, respectively. The overall mortality in the 84 patients was 6%, and the actuarial survival at 1 year was 93%. Volume reduction surgery is a promising therapeutic option for patients with an appropriate pattern of emphysema. Improvement has been sustained for more than 1 year, and long-term follow-up is planned to ascertain the duration of the benefits.

Effect of hypothermia on the pharmacokinetics of ethanol in piglets.

The effect of hypothermia (29 C) on the pharmacokinetics of ethanol was studied in eight piglets serving as their own normothermic controls. Ten milliliters of 12% ethanol per kilogram were infused over 30 minutes, and serum ethanol concentrations were measured for seven hours. Ethanol concentration data were fitted to one-compartment open model assuming Michaelis Menten elimination kinetics. During hypothermia, ethanol concentrations were consistently higher than during normothermia. This observation could be explained by both a significantly smaller distribution volume of ethanol during hypothermia (0.71 +/- 0.03 L/kg at 29 C and 0.84 +/- 0.05 L/kg at 37 C, P less than .02) and a significantly slower maximum velocity of metabolism of ethanol (Vm) during hypothermia (1.12 +/- 0.11 mg/kg.min vs. 1.83 +/- 0.21 mg/kg.min, P less than .01). Our study indicates that during hypothermia, ethanol stays significantly longer in the circulation in piglets. Potentially, this may contribute to a more profound effect from the ethanol.

The use of infants in drug research when there is no direct benefit to them: a survey of Canadian health care professionals serving on ethics committees.

Canadian health care professionals and lawyers serving on ethics committees were questioned about their views on pharmacokinetic research in newborn infants who are not likely to benefit directly from the results. Of the 50 respondents 13 felt that blood samples should be taken only for therapeutic reasons; 10 of the 13 argued that additional blood samples should not be taken, because there is no direct benefit to the infant; and 8 felt that proxy consent cannot be given for invasive nontherapeutic research. Four of the five participating lawyers would not permit additional blood samples to be taken. Of the 37 respondents who would permit additional blood samples to be taken, 27 felt that the number of samples taken should depend on the researcher's justification for that number of samples; only 7 of the respondents had a clear idea of what the "upper limit" of the number of blood samples should be.

Purine nucleoside phosphorylase deficiency: altered kinetic properties of a mutant enzyme.

Erythrocyte purine nucleoside phosphorylase from two brothers had 0.5% of normal activity. It differed from the normal enzyme by a tenfold increase in the Michaelis constant for inosine, an inability of inosine to protect against thermal lability, and a more positive net charge. The altered kinetic properties may account for the milder disease in the patients compared to the previously described cases. The data provide evidence for a structural gene mutation and genetic heterogeneity in the new disease of purine nucleoside phosphorylase deficiency and T cell dysfunction.