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ABSTRACT: Previous studies of children with homozygous sickle cell anemia (SCA) show impaired growth and maturation. The correlation of this suboptimal growth with metabolic and hematological factors during puberty is poorly understood.
We studied a group of pre-adolescent children with SCA (19 males, 14 females) and healthy controls (16 males, 15 females) matched for race, sex, body size, and pubertal development. Height, weight, body mass index (BMI), and body composition changes were longitudinally assessed over a 2-year period and compared between the groups and with Z scores based on US growth charts. These changes were correlated with hemoglobin (Hgb) concentration and with energy expenditure (EE) measured using indirect whole-room calorimetry.
Children with SCA progressed through puberty slower than control children. While, after 2 years, pubertal males with SCA were shorter, their annual increases in weight were not different from controls. The mean fat free mass (FFM) increments were significantly less in males and females with SCA than in control children. In males with SCA, growth in height declined over time and was significantly slower than in matched controls (P < 0.05).
Growth delays were present during puberty in children with SCA. Decreased growth velocity in children with SCA was independently associated with decreased Hgb concentration and increased total EE.
Pediatric Blood & Cancer 07/2009; 53(4):635-41. · 1.89 Impact Factor
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ABSTRACT: Physical activity (PA) and energy expenditure (EE) in children are frequently assessed using portable activity monitors. Algorithms used to predict EE by these monitors are often based on adult populations and may not be accurate for children.
To evaluate the accuracy of the SenseWear Pro Armband (SWA) for assessing EE in African American children during treadmill exercise, sedentary activities, rest, sleep, and total 24-h EE, using indirect room calorimetry (IRC) as a reference standard.
Participants were healthy African American children (10 boys, 11 girls; age: 11.6 +/- 0.9 yr; weight: 47.3 +/- 13.0 kg; height: 151.6 +/- 8.8 cm; BMI: 20.4 +/- 4.8 kg.m). EE was measured simultaneously using IRC and SWA during a 24-h stay in the IRC. Recorded activities included sedentary behaviors, treadmill exercise, rest periods, and sleep. Results from both methods were matched minute-by-minute and compared by Bland-Altman plot. Multiple linear regression analysis was used to describe the relationship between EE assessed by both methods and children's descriptive characteristics.
SWA overestimated EE compared with IRC during all activities and time periods, ranging from 116% during sleep to 143% during rest after treadmill exercise. The SWA-predicted EE was improved by using linear regression modeling. Simple equations for sedentary activities and treadmill exercise were EE [kcal.min] = 0.462EE (SWA) [kcal.min] + 0.015 x body weight [kg], and EE [kcal.min] = 0.637EE (SWA) [kcal.min] + 0.034 x body weight [kg], respectively. The prediction equation for RMR was RMR [kcal.min] = 0.453EE (SWA) [kcal.min] + 0.011 x body weight [kg].
EE estimated using SWA was significantly higher than EE measured using IRC in African American children ages 10-14 yr. Bias in individual EE estimated using SWA could be improved by an adjustment for the body weight of a child. The SWA manufacturer should work with researchers on improving existing algorithms for children.
Medicine & Science in Sports & Exercise 05/2008; 40(4):699-706. · 4.43 Impact Factor
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ABSTRACT: Sickle cell anemia (HbSS) is characterized by hypermetabolism, chronic inflammation, and increased oxidative stress, but the relationship between these factors is undefined. In this study, we examined indicators of inflammatory process and markers of oxidative damage and their impact on resting energy expenditure (REE) in stable HbSS adolescents (n = 35) and healthy controls carrying normal hemoglobin genotype (HbAA) (n = 39). C-reactive protein (CRP), white blood cell (WBC) count, and proinflammatory cytokines were measured as markers of inflammation and 2,3-dinor-5,6-dihydro-15-F2t-isoprostane (F2-IsoPM) as a marker of oxidative stress. REE was measured by indirect calorimetry. WBC counts (11.90 +/- 5.3 x10/muL versus 5.6 +/- 1.9 x10/muL; p < 0.001), serum CRP (9.1 +/- 11.0 mug/mL versus 0.4 +/- 0.7 mug/mL; p < 0.001) and serum IL-8 (7.5 +/- 4.4 pg/mL versus 5.5 +/- 4.8 pg/mL; p = 0.011) were higher in HbSS than HbAA, suggesting an anti-inflammatory response in HbSS. Higher urinary F2-IsoPM in HbSS (1.2 +/- 0.4 versus 0.7 +/- 0.3 ng/mg creatinine; p < 0.001) indicates increased oxidative stress. Fat free mass (FFM), hemoglobin (Hgb), interleukin (IL)-8, and F2-IsoPM were independent predictors of REE in HbSS (overall r = 0.778; p < 0.001). Low-grade inflammation and increased oxidative stress are present in adolescents with HbSS in the absence of acute crisis, and their markers are correlated with elevated REE.
Pediatric Research 03/2007; 61(2):233-8. · 2.70 Impact Factor
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ABSTRACT: To further investigate the effect of dietary vitamin A (VA) intake on milk VA concentrations and pup VA status, female rats were fed 2 concentrations of VA [0 (n = 9) or 50 micromol/kg diet (n = 10)] during pregnancy and lactation. Plasma retinol concentrations were significantly higher (30-40%) during lactation than before pregnancy or after weaning but were not influenced by dietary VA. In rats fed VA, VA concentrations during lactation were significantly higher in milk (1.5-3 times), mammary tissue (>100%), liver (4 times), pup plasma (20-40%), and pup liver (1.1-6.7 times). In Expt. 2, when VA intake was switched on d 7 of lactation from 0 to 50 micromol/kg, milk VA concentrations (2.24 +/- 0.42 micromol/L; mean +/- SD, n = 6) increased significantly (1.7 times) by d 9 to the same level as in rats administered 50 micromol/kg (6.04 +/- 0.60 micromol/L; n = 6). When VA was removed from the diet on d 7, concentrations declined significantly (by 50%) and by d 11 were the same as those in rats given 0 micromol/kg. We conclude that the rapid effect of changes in dietary VA intake are attributable to changes in the delivery of chylomicron VA to mammary tissue and milk.
Journal of Nutrition 02/2006; 136(1):128-32. · 3.92 Impact Factor
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ABSTRACT: The chronic hemolytic anemia experienced by sickle cell disease (SCD) patients leads to adverse effects on oxygen transport by the blood and to a decrease in oxygen availability for peripheral tissues. Limited tissue oxygen availability has the potential to modify events of intracellular metabolism and, thus, alter lipid homeostasis.
The impact of SCD on plasma fatty acid homeostasis was determined in 8 African American SCD patients and in 6 healthy African American control subjects under postabsorptive conditions and during a 3-hour IV infusion of a nutrient solution containing lipid, glucose, and amino acids.
SCD patients had higher fasting levels of plasma nonesterified fatty acids (NEFA), triglycerides, and phospholipids than healthy controls. Similarly, SCD patients had higher fasting levels of fatty acids in plasma triglycerides and phospholipids than healthy controls. Infusion of nutrients resulted in equivalent plasma NEFA profiles, total NEFA, and triglycerides in SCD patients and controls. However, the plasma phospholipid concentrations and fatty acid composition of plasma triglycerides and phospholipids were significantly higher in SCD patients; in particular, plasma pools of oleic acid were consistently increased in SCD. Plasma free oleic acid levels were elevated basally, leading to increased oleic acid content in triglycerides and phospholipids both post absorptively and during nutrient infusion.
There is an underlying defect in lipid metabolism associated with SCD best manifested during the fasting state. This abnormality in lipid homeostasis has the potential to alter red blood cell (RBC) membrane fluidity and function in SCD patients.
Journal of Parenteral and Enteral Nutrition 31(4):263-8. · 3.29 Impact Factor
