Whole body protein turnover and resting metabolic rate in homozygous sickle cell disease

Maternal malnutrition during pregnancy among women with sickle cell disease

OBJECTIVE

The objective of this study was to compare the nutritional status and dietary intake of pregnant women with sickle cell disease (SS hemoglobinopathy and SC hemoglobinopathy) to healthy controls and report the maternal and perinatal outcomes.

METHODS

This is a prospective, longitudinal cohort study. Pregnant women with a diagnosis of sickle cell disease and control group were recruited in an outpatient clinic of a tertiary care hospital in São Paulo, Brazil. Maternal anthropometric data and dietary intake data were collected at the second and third trimesters.

RESULTS

A total of 49 pregnancies complicated by sickle cell disease were included. Prepregnancy body mass index was significantly lower in the SS hemoglobinopathy group (n=26, median 20.3 kg/m2) than the SC hemoglobinopathy group (n=23, 22.7 kg/m2) or control group (n=33, 23.2 kg/m2, p<0.05). The prepregnancy nutritional status revealed significantly more women classified as underweight in the SS hemoglobinopathy group (15.4%) than in the SC hemoglobinopathy group (4.4%) and control group (1.6%, p=0.009). In the second trimester, maternal protein intake was significantly lower in SS hemoglobinopathy (73.2 g/day) and SC hemoglobinopathy (68.8 g/day) than in the control group (95.7 g/day, p=0.004). In the third trimester, only SS hemoglobinopathy mothers showed dietary intake of protein significantly lower than that of the controls (67.5 g/day vs. 92.8 g/day, p=0.02). Vitamin A and E consumption was also reduced in the third trimester in the SS hemoglobinopathy group (p<0.05).

CONCLUSION

The nutritional status of pregnant women with SS hemoglobinopathy is characterized by a state of undernutrition. The lower protein intake in the second and third trimesters of pregnant women with SS hemoglobinopathy may contribute to this condition. Undernourishment is a serious complication of sickle cell disease, primarily during pregnancy, and it should be addressed during the prenatal period.

Hypothesis: Low Vitamin A and D Levels Worsen Clinical Outcomes When Children with Sickle Cell Disease Encounter Parvovirus B19

Human parvovirus B19 causes life-threatening anemia due to transient red cell aplasia (TRCA) in individuals with sickle cell disease (SCD). Children with SCD experiencing profound anemia during TRCA often require red blood cell transfusions and hospitalization. The prevalence of vitamin deficiencies in SCD is high and deficiencies are associated with respiratory and pain symptoms, but the effects of vitamins on acute infection with parvovirus B19 remain unclear. We performed a clinical study in which 20 SCD patients hospitalized with parvovirus B19 infections (Day 0) were monitored over a 120-day time course to query relationships between vitamins A and D and clinical outcomes. There were significant negative correlations between Day 0 vitamin levels and disease consequences (e.g., red blood cell transfusion requirements, inflammatory cytokines). There were significant positive correlations (i) between Day 0 vitamins and peak virus-specific antibodies in nasal wash, and (ii) between Day 0 virus-specific serum plus nasal wash antibodies and absolute reticulocyte counts. There was a significant negative correlation between Day 0 virus-specific serum antibodies and virus loads. To explain the results, we propose circular and complex mechanisms. Low baseline vitamin levels may weaken virus-specific immune responses to permit virus amplification and reticulocyte loss; consequent damage may further reduce vitamin levels and virus-specific immunity. While the complex benefits of vitamins are not fully understood, we propose that maintenance of replete vitamin A and D levels in children with SCD will serve as prophylaxis against parvovirus B19-induced TRCA complications.

The Effects of Treatment with Blood Transfusion, Iron Chelation and Hydroxyurea on Puberty, Growth and Spermatogenesis in Sickle Cell Disease (SCD): A short update

Sickle cell disease (SCD) is traditionally associated with growth failure and delayed puberty. Wasting and stunting are still prevalent in children and adolescents with SCD, especially in developing countries. In addition, sperm abnormalities are frequent in males with SCD, with high rates of low sperm density, low sperm counts, poor motility, and increased abnormal morphology. Severe anaemia, vaso-occlusive attacks with ischemic injury to different organs including the pituitary gland and testis, and nutritional factors are incriminated in the pathogenesis of defective growth, puberty, and spermatogenesis. There is great phenotypic variability among patients with SCD. The variability in the clinical severity of SCD can partly be explained by genetic modifiers, including HbF level and co-inheritance of α-thalassaemia. In the past, severe disease led to early mortality. Advancements in treatment have allowed patients with SCD to have a longer and better quality of life. For most patients, the mainstays of treatment are preventive and supportive. For those with severe SCD, three major therapeutic options are currently available: erythrocyte transfusion or exchange, hydroxyurea and hematopoietic stem cell transplantation. In this mini review the authors tried to recognize, delineate, and update knowledge on abnormalities due to SCD from those created by the use of different treatment modalities. (www.actabiomedica.it)

Nutritional perspectives on sickle cell disease in Africa: a systematic review

BACKGROUND

Sickle cell disease (SCD) is an inherited blood disorder that predominantly affects individuals in sub-Saharan Africa. However, research that elucidates links between SCD pathophysiology and nutritional status in African patients is lacking. This systematic review aimed to assess the landscape of studies in sub-Saharan Africa that focused on nutritional aspects of SCD, and highlights gaps in knowledge that could inform priority-setting for future research.

METHODS

The study was conducted using the Preferred Reporting Items for Systematic Reviews and Meta-Analysis (PRISMA) guidelines. Inclusion criteria comprised original, peer-reviewed research published between January 1995 and November 2020 involving individuals in Africa with any phenotypic variant of SCD and at least one nutritional status outcome. Nutritional status outcomes were defined as those that assessed dietary intakes, growth/anthropometry, or nutritional biomarkers. Databases used were Ovid Embase, Medline, Biosis and Web of Science.

RESULTS

The search returned 526 articles, of which 76 were included in the final analyses. Most investigations (67%) were conducted in Nigeria. Studies were categorized into one of three main categories: descriptive studies of anthropometric characteristics (49%), descriptive studies of macro- or micronutrient status (41%), and interventional studies (11%). Findings consistently included growth impairment, especially among children and adolescents from sub-Saharan Africa. Studies assessing macro- and micronutrients generally had small sample sizes and were exploratory in nature. Only four randomized trials were identified, which measured the impact of lime juice, long-chain fatty acids supplementation, ready-to-use supplementary food (RUSF), and oral arginine on health outcomes.

CONCLUSIONS

The findings reveal a moderate number of descriptive studies, most with small sample sizes, that focused on various aspects of nutrition and SCD in African patients. There was a stark dearth of interventional studies that could be used to inform evidence-based changes in clinical practice. Findings from the investigations were generally consistent with data from other regional settings, describing a significant risk of growth faltering and malnutrition among individuals with SCD. There is an unmet need for clinical research to better understand the potential benefits of nutrition-related interventions for patients with SCD in sub-Saharan Africa to promote optimal growth and improve health outcomes.

Survival of the cheapest: how proteome cost minimization drives evolution

Darwin's theory of evolution emphasized that positive selection of functional proficiency provides the fitness that ultimately determines the structure of life, a view that has dominated biochemical thinking of enzymes as perfectly optimized for their specific functions. The 20th-century modern synthesis, structural biology, and the central dogma explained the machinery of evolution, and nearly neutral theory explained how selection competes with random fixation dynamics that produce molecular clocks essential e.g. for dating evolutionary histories. However, quantitative proteomics revealed that selection pressures not relating to optimal function play much larger roles than previously thought, acting perhaps most importantly via protein expression levels. This paper first summarizes recent progress in the 21st century toward recovering this universal selection pressure. Then, the paper argues that proteome cost minimization is the dominant, underlying 'non-function' selection pressure controlling most of the evolution of already functionally adapted living systems. A theory of proteome cost minimization is described and argued to have consequences for understanding evolutionary trade-offs, aging, cancer, and neurodegenerative protein-misfolding diseases.

Exacerbated metabolic changes in skeletal muscle of sickle cell mice submitted to an acute ischemia-reperfusion paradigm

Sickle cell disease (SCD) is characterized by painful vaso-occlusive crisis. While there are several metabolic abnormalities potentially associated with muscular ischemia-reperfusion cycles that could be harmful in the context of SCD, the metabolic consequences of such events are still unknown. Ten controls (HbAA), thirteen heterozygous (HbAS), and ten homozygous (HbSS) SCD mice were submitted to a standardized protocol of rest-ischemia-reperfusion of the left leg during which adenosine triphosphate, phosphocreatine, and inorganic phosphate concentrations as well as intramuscular pH were measured using phosphorous magnetic resonance spectroscopy (MRS). Forty-eight hours later, skeletal muscles were harvested. Oxidative stress markers were then measured on the tibialis anterior. At the end of the ischemic period, HbSS mice had a lower pH value as compared with the HbAA and HbAS groups (P<0.01). During the reperfusion period, the initial rate of phosphocreatine resynthesis was lower in HbSS mice as compared with HbAA (P<0.05) and HbAS (P<0.01) animals. No significant difference among groups was observed regarding oxidative stress markers. HbSS mice displayed a higher intramuscular acidosis during the ischemic period while their mitochondrial function was impaired as compared with their HbAA and HbAS counterparts. These metabolic abnormalities could worsen the complications related to the pathology of SCD.

Serum 25-Hydroxyvitamin D and Diet Mediates Vaso-Occlusive Related Hospitalizations in Sickle-Cell Disease Patients

Sickle cell disease (SCD) is a genetic disorder resulting from the presence of mutated hemoglobin S (HbS). Homozygous carriers will present with early manifestations of painful vaso-occlusive crises. SCD patients have been reported to be severely deficient in vitamin D (<20 ng/mL). Four years (2010–2014) of individual de-identified Sickle Cell Clinic of Southern Louisiana (SCCSL-SCD) patient records were analyzed for vitamin D status and the level of crisis-related ER/hospital utilization. To determine the dietary, and behavioral mediators of SCD-crisis in our study population, a cohort of 102 SCCSL-SCD patients were administered a survey that evaluated sun exposure, dietary behaviors, and pain frequency and severity. Patients with circulating levels of 25(OH)D₃ less than 14.1 ng/mL reported having more crisis-related hospital visits per year (10) than patients with 25(OH)D₃ serum levels >34 ng/mL. The result of the dietary survey detailed a relationship between patients who reported to have “Almost Never” consumed fish or milk in their diets and more frequent hospital stays and ER visits than those who reported consuming these products on a daily basis. Those who consumed these foods in their diet several times a month also had fewer ER visits when compared to the “Almost Never” category.

Regional oxygen extraction predicts border zone vulnerability to stroke in sickle cell disease

OBJECTIVE

To determine mechanisms underlying regional vulnerability to infarction in sickle cell disease (SCD) by measuring voxel-wise cerebral blood flow (CBF), oxygen extraction fraction (OEF), and cerebral metabolic rate of oxygen utilization (CMRO2) in children with SCD.

METHODS

Participants underwent brain MRIs to measure voxel-based CBF, OEF, and CMRO2. An infarct heat map was created from an independent pediatric SCD cohort with silent infarcts and compared to prospectively obtained OEF maps.

RESULTS

Fifty-six participants, 36 children with SCD and 20 controls, completed the study evaluation. Whole-brain CBF (99.2 vs 66.3 mL/100 g/min, p < 0.001), OEF (42.7% vs 28.8%, p < 0.001), and CMRO2 (3.7 vs 2.5 mL/100 g/min, p < 0.001) were higher in the SCD cohort compared to controls. A region of peak OEF was identified in the deep white matter in the SCD cohort, delineated by a ratio map of average SCD to control OEF voxels. CMRO2 in this region, which encompassed the CBF nadir, was low relative to all white matter (p < 0.001). Furthermore, this peak OEF region colocalized with regions of greatest infarct density derived from an independent SCD cohort.

CONCLUSIONS

Elevated OEF in the deep white matter identifies a signature of metabolically stressed brain tissue at increased stroke risk in pediatric patients with SCD. We propose that border zone physiology, exacerbated by chronic anemic hypoxia, explains the high risk in this region.

Growth and Growth hormone - Insulin Like Growth Factor -I (GH-IGF-I) Axis in Chronic Anemias

Anaemia is a global public health problem affecting both developing and developed countries with major consequences for human health as well as social and economic development. It occurs at all stages of the life cycle, but is more prevalent in pregnant women and young children. Iron deficiency anaemia (IDA) was considered to be among the most important contributing factors to the global burden of disease. Prolonged and/or chronic anemia has a negative effect on linear growth especially during the rapid phases (infancy and puberty). Additionally infants with chronic IDA have delayed cognitive, motor, and affective development that may be long-lasting. In view of the significant impact of chronic anemias on growth, pediatricians endocrinologists and hematologists should advocate primary prevention and screening for growth disturbance in these forms of anemias. The extent of the negative effect of different forms of chronic anemias on linear growth and its possible reversibilty is addressed in this review. The possible mechanisms that may impair growth in the different forms of anemias are addressed with special attention to their effect on the growth hormone (GH) – insulin like growth factor -I (IGF-I). (www.actabiomedica.it)

Body composition and grip strength are improved in transgenic sickle mice fed a high-protein diet

Key pathophysiology of sickle cell anaemia includes compensatory erythropoiesis, vascular injury and chronic inflammation, which divert amino acids from tissue deposition for growth/weight gain and muscle formation. We hypothesised that sickle mice maintained on an isoenergetic diet with a high percentage of energy derived from protein (35 %), as opposed to a standard diet with 20 % of energy derived from protein, would improve body composition, bone mass and grip strength. Male Berkeley transgenic sickle mice (S; n 8-12) were fed either 20 % (S20) or 35 % (S35) diets for 3 months. Grip strength (BIOSEB meter) and body composition (dual-energy X-ray absorptiometry scan) were measured. After 3 months, control mice had the highest bone mineral density (BMD) and bone mineral content (BMC) (P < 0·005). S35 mice had the largest increase in grip strength. A two-way ANOVA of change in grip strength (P = 0·043) attributed this difference to genotype (P = 0·025) and a trend in type of diet (P = 0·067). l-Arginine (l-Arg) supplementation of the 20 % diet was explored, as a possible mechanism for improvement obtained with the 35 % diet. Townes transgenic sickle mice (TS; n 6-9) received 0·8, 1·6, 3·2 or 6·4 % l-Arg based on the same protocol and outcome measures used for the S mice. TS mice fed 1·6 % l-Arg for 3 months (TS1.6) had the highest weight gain, BMD, BMC and lean body mass compared with other groups. TS3.2 mice showed significantly more improvement in grip strength than TS0·8 and TS1.6 mice (P < 0·05). In conclusion, the high-protein diet improved body composition and grip strength. Outcomes observed with TS1.6 and TS3.2 mice, respectively, confirm the hypothesis and reveal l-Arg as part of the mechanism.

Microvascular oxygen consumption during sickle cell pain crisis

Sickle cell disease is an inherited blood disorder characterized by chronic hemolytic anemia and episodic vaso-occlusive pain crises. Vaso-occlusion occurs when deoxygenated hemoglobin S polymerizes and erythrocytes sickle and adhere in the microvasculature, a process dependent on the concentration of hemoglobin S and the rate of deoxygenation, among other factors. We measured oxygen consumption in the thenar eminence during brachial artery occlusion in sickle cell patients and healthy individuals. Microvascular oxygen consumption was greater in sickle cell patients than in healthy individuals (median [interquartile range]; sickle cell: 0.91 [0.75-1.07] vs healthy: 0.75 [0.62-0.94] -ΔHbO2/min, P < .05) and was elevated further during acute pain crisis (crisis: 1.10 [0.78-1.30] vs recovered: 0.88 [0.76-1.03] -ΔHbO2/min, P < .05). Increased microvascular oxygen consumption during pain crisis could affect the local oxygen saturation of hemoglobin when oxygen delivery is limiting. Identifying the mechanisms of elevated oxygen consumption during pain crisis might lead to the development of new therapeutic interventions. This trial was registered at www.clinicaltrials.gov as #NCT01568710.

Somatic growth and lung function in sickle cell disease

Somatic growth is a key indicator of overall health and well-being with important prognostic implications in the management of chronic disease. Worldwide studies of growth in children and adults with SCD have predominantly shown delayed growth (especially in terms of body weight) that is gradual and progressive in nature. However, more recent studies have shown that a substantial number of patients with SCD have normal weight gain whereas some are even obese. Height in patients with SCD is not universally affected even among those with suboptimal weight gain, whereas some achieve the same or greater height than healthy controls. The relationship between somatic growth and lung function in SCD is not yet clearly defined. As a group, patients with SCD tend to have lower lung volumes compared with healthy controls. These findings are similar across the age spectrum and across ethnic/racial lines regardless of the differences in body weight. Several mechanisms and risk factors have been proposed to explain these findings. These include malnutrition, racial differences and socioeconomic status. In addition, there are structural changes of the thorax (specifically the anterio-posterior chest diameter and anterio-posterior to lateral chest ratio) specific to sickle cell disease, that potentially interfere with normal lung growth. Although, caloric and protein intake have been shown to improve both height and weight, the composition of an optimal diet remains unclear. The following article reviews the current knowledge and controversies regarding somatic growth and its relationship with lung function in sickle cell disease (SCD) as well as the role of specific deficiencies of certain micronutrients.

A model of proteostatic energy cost and its use in analysis of proteome trends and sequence evolution

A model of proteome-associated chemical energetic costs of cells is derived from protein-turnover kinetics and protein folding. Minimization of the proteostatic maintenance cost can explain a range of trends of proteomes and combines both protein function, stability, size, proteostatic cost, temperature, resource availability, and turnover rates in one simple framework. We then explore the ansatz that the chemical energy remaining after proteostatic maintenance is available for reproduction (or cell division) and thus, proportional to organism fitness. Selection for lower proteostatic costs is then shown to be significant vs. typical effective population sizes of yeast. The model explains and quantifies evolutionary conservation of highly abundant proteins as arising both from functional mutations and from changes in other properties such as stability, cost, or turnover rates. We show that typical hypomorphic mutations can be selected against due to increased cost of compensatory protein expression (both in the mutated gene and in related genes, i.e. epistasis) rather than compromised function itself, although this compensation depends on the protein's importance. Such mutations exhibit larger selective disadvantage in abundant, large, synthetically costly, and/or short-lived proteins. Selection against increased turnover costs of less stable proteins rather than misfolding toxicity per se can explain equilibrium protein stability distributions, in agreement with recent findings in E. coli. The proteostatic selection pressure is stronger at low metabolic rates (i.e. scarce environments) and in hot habitats, explaining proteome adaptations towards rough environments as a question of energy. The model may also explain several trade-offs observed in protein evolution and suggests how protein properties can coevolve to maintain low proteostatic cost.

Resting energy expenditure and the effects of muscle wasting in patients with chronic heart failure: results from the Studies Investigating Comorbidities Aggravating Heart Failure (SICA-HF)

OBJECTIVES

Muscle wasting is common in patients with chronic heart failure (HF) and worsens functional status. Protein catabolism is characteristic of muscle wasting and contributes to resting energy expenditure (REE). Glucagonlike peptide 1 (GLP-1) is linked to REE in healthy individuals. We aimed to evaluate (1) whether REE is elevated in patients with HF with muscle wasting, and (2) whether basal GLP-1 levels are linked to REE in HF.

DESIGN

Cross-sectional study.

SETTING

Ambulatory patients with HF were recruited at the Charité Medical School, Campus Virchow-Klinikum, Berlin, Germany.

PARTICIPANTS

A total of 166 patients with HF and 27 healthy controls participating in the Studies Investigating Co-morbidities Aggravating Heart Failure (SICA-HF) were enrolled. GLP-1 was measured in 55 of these patients.

MEASUREMENTS

Body composition was measured by dual-energy X-ray absorptiometry (DEXA). Muscle wasting was defined as appendicular lean mass of at least 2 SDs below values of a healthy young reference group. REE was measured by indirect calorimetry. GLP-1 was assessed by ELISA.

RESULTS

Thirty-four of 166 patients (mean age 67.4 ± 10.2 years, 77.7% male, New York Heart Association class 2.3 ± 0.6) presented with muscle wasting. REE in controls and patients with muscle wasting was significantly lower than in patients without muscle wasting (1579 ± 289 and 1532 ± 265 vs 1748 ± 359 kcal/d, P = .018 and P = .001, respectively). REE normalized for fat-free mass (FFM) using the ratio method (REE/FFM) and analysis of covariance was not different (P = .23 and .71, respectively). GLP-1 did not significantly correlate with REE (P = .49), even not after controlling for FFM using multivariable regression (P = .15).

CONCLUSIONS

Differences in REE are attributable to lower FFM. GLP-1 does not relate to REE in patients with HF, possibly because of HF-related effects on REE.

Normal muscle oxygen consumption and fatigability in sickle cell patients despite reduced microvascular oxygenation and hemorheological abnormalities

Background/Aim

Although it has been hypothesized that muscle metabolism and fatigability could be impaired in sickle cell patients, no study has addressed this issue.

Methods

We compared muscle metabolism and function (muscle microvascular oxygenation, microvascular blood flow, muscle oxygen consumption and muscle microvascular oxygenation variability, which reflects vasomotion activity, maximal muscle force and local muscle fatigability) and the hemorheological profile at rest between 16 healthy subjects (AA), 20 sickle cell-hemoglobin C disease (SC) patients and 16 sickle cell anemia (SS) patients.

Results

Muscle microvascular oxygenation was reduced in SS patients compared to the SC and AA groups and this reduction was not related to hemorhelogical abnormalities. No difference was observed between the three groups for oxygen consumption and vasomotion activity. Muscle microvascular blood flow was higher in SS patients compared to the AA group, and tended to be higher compared to the SC group. Multivariate analysis revealed that muscle oxygen consumption was independently associated with muscle microvascular blood flow in the two sickle cell groups (SC and SS). Finally, despite reduced muscle force in sickle cell patients, their local muscle fatigability was similar to that of the healthy subjects.

Conclusions

Sickle cell patients have normal resting muscle oxygen consumption and fatigability despite hemorheological alterations and, for SS patients only, reduced muscle microvascular oxygenation and increased microvascular blood flow. Two alternative mechanisms can be proposed for SS patients: 1) the increased muscle microvascular blood flow is a way to compensate for the lower muscle microvascular oxygenation to maintain muscle oxygen consumption to normal values or 2) the reduced microvascular oxygenation coupled with a normal resting muscle oxygen consumption could indicate that there is slight hypoxia within the muscle which is not sufficient to limit mitochondrial respiration but increases muscle microvascular blood flow.

Pathological basis of symptoms and crises in sickle cell disorder: implications for counseling and psychotherapy

Sickle Cell Disorder (SCD) is a congenital hemoglobinopathy. There is little in literature regarding the psychological variables affecting individuals living with SCD and all of the significant people around them. There are also limited numbers of trained clinical psychologists and genetic counselors to cater for the psychotherapeutic needs of individuals living with SCD. Even among those who have been trained, only a few might have fully grasped the complexities of the disease pathology.Early understanding of its pathological nature, sources, types, complications, pathophysiological basis, and clinical severity of symptoms among clinical psychologists, genetic counselors and psychotherapists, as well as general medical practitioners, could guide them in providing holistic care for dealing with and reducing pain among individuals living with SCD. It could allow risk-based counseling for families and individuals. It could also justify the early use of disease-modifying or curative interventions, such as hydroxyurea (HU), chronic transfusions (CTs), or stem-cell transplantation (SCT) by general medical practitioners. Hence, the need for this paper on the pathophysiology of SCD.

The Role of Nutrition in Sickle Cell Disease

Finding a widely available cure for sickle cell anemia (HbSS) still remains a challenge one hundred years after its discovery as a genetically inherited disease. However, growing interest in the nutritional problems of the disease has created a body of literature from researchers seeking nutritional alternatives as a means of decreasing morbidity and improving quality of life among HbSS patients. This review demonstrates that over the past 30 years the role of protein/energy deficiency in HbSS has been more clearly defined via direct measurements, leading to the concept of a relative shortage of nutrients for growth and development, despite apparently adequate dietary intakes. Although there is still a paucity of data supporting the efficacy of macronutrient supplementation, it is becoming clearer that recommended dietary allowances (RDAs) for the general population are insufficient for the sickle cell patient. A similar shortage is likely to be true for micronutrient deficiencies, including recent findings of vitamin D deficiency that may be associated with incomplete ossification and bone disease, which are well known complications of HbSS disease. We conclude that there is need for more effort and resources to be dedicated to research (including supplementation studies of larger sample size) aimed at establishing specific RDAs for HbSS patients, much like the specific RDAs developed for pregnancy and growth within the general population.

Growth and nutritional status of children with homozygous sickle cell disease

BACKGROUND

Poor growth and under-nutrition are common in children with sickle cell disease (SCD). This review summarises evidence of nutritional status in children with SCD in relation to anthropometric status, disease severity, body composition, energy metabolism, micronutrient deficiency and endocrine dysfunction.

METHODS

A literature search was conducted on the Medline/PUBMED, SCOPUS, SciELO and LILACS databases to July 2007 using the keywords sickle cell combined with nutrition, anthropometry, growth, height and weight, body mass index, and specific named micronutrients.

RESULTS

Forty-six studies (26 cross-sectional and 20 longitudinal) were included in the final anthropometric analysis. Fourteen of the longitudinal studies were conducted in North America, the Caribbean or Europe, representing 78.8% (2086/2645) of patients. Most studies were observational with wide variations in sample size and selection of reference growth data, which limited comparability. There was a paucity of studies from Africa and the Arabian Peninsula, highlighting a large knowledge gap for low-resource settings. There was a consistent pattern of growth failure among affected children from all geographic areas, with good evidence linking growth failure to endocrine dysfunction, metabolic derangement and specific nutrient deficiencies.

CONCLUSIONS

The monitoring of growth and nutritional status in children with SCD is an essential requirement for comprehensive care, facilitating early diagnosis of growth failure and nutritional intervention. Randomised controlled trials are necessary to assess the potential benefits of nutritional interventions in relation to growth, nutritional status and the pathophysiology of the disease.

C-reactive protein and interleukin-6 are decreased in transgenic sickle cell mice fed a high protein diet

Sickle cell disease is associated with hypermetabolism and a consequent shortage of substrates for normal growth and healthy immune response. The protein:energy ratio is a major determinant of dietary adequacy; the requirement for optimal growth of control mice is 20% of energy from dietary protein. This study investigated the efficacy of increased dietary protein for improving weight gain and reducing inflammation in the Berkeley sickle cell mouse model (S). The study examined the effect of diet on weight gain and circulating levels of 2 inflammatory proteins, C-reactive protein (CRP), and cytokine interleukin-6 (IL-6). Male C57BL/6 (C) control (n = 8) and S mice (n = 8) were randomized at weaning to 40 d of isoenergetic diets containing 20% (normal) and 35% (high) of energy from protein (C20, C35, S20, S35), replacing dextrin. Rate of weight gain was calculated and plasma CRP and IL-6 concentrations determined by ELISA. Liver mRNA expression of these proteins was measured by real-time PCR and L-arginase by colorimetric assay. S35 mice tended to gain weight more rapidly than S20 mice (P = 0.06) and more rapidly than C35 mice (P < 0.01). Circulating CRP and IL-6 levels were also lower in S35 mice than in S20 mice (P < 0.05), as was liver CRP mRNA expression (P < 0.01). These results demonstrate that introducing a high protein diet at weaning attenuates the steady-state inflammation in this S mouse model. Dietary L-arginine availability was investigated as a possible mechanism for increased nitric oxide production and consequent reduced inflammation.

Effects of delayed pubertal development, nutritional status, and disease severity on longitudinal patterns of growth failure in children with sickle cell disease

Previous studies of children with sickle cell disease (SCD) reported poor growth and delayed maturation. However, the prevalence, magnitude, and correlates of suboptimal growth remain poorly understood. A prospective longitudinal study was undertaken to determine the effects of disease severity and nutritional status on growth, an indicator of childhood well-being. Children, birth to 18 y of age, with SCD-SS were evaluated annually for 4 y. Growth, nutritional status, skeletal and sexual maturation, disease severity, dietary intake, and maternal education were assessed. In this sample of 148 children (78 females), growth in height, weight, or body mass index declined in 84% of subjects; 38% fell below the 5th percentile in one or more measures. Puberty was delayed 1 to 2 y, and median age at menarche was 13.2 y. Skeletal age was delayed by 0.7 +/- 1.4 y overall and by 1.3 +/- 1.5 y in children 10 to 15 y old. Height status declined over time and was positively associated with advancing puberty and hematological measures in girls, and nutritional status in girls and boys. Growth failure and maturational delay remain significant chronic problems in children with SCD-SS and are related to potentially modifiable factors such as nutritional status.

Energy expenditure, inflammation, and oxidative stress in steady-state adolescents with sickle cell anemia

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.

Erythropoiesis and myocardial energy requirements contribute to the hypermetabolism of childhood sickle cell anemia

OBJECTIVES

We hypothesized that an elevated hemoglobin synthesis rate (SynHb) and myocardial oxygen consumption (MVO2) contribute to the excess protein and energy metabolism reported in children with sickle cell anemia.

PATIENTS AND METHODS

Twelve children (6-12 years old) with asymptomatic sickle cell and 9 healthy children matched for age and sex were studied. Measurements were whole-body protein turnover by [1-C]leucine, SynHb by [N]glycine, resting energy expenditure by indirect calorimetry and the systolic blood pressure-heart rate product used as an index of MVO2. Protein energy cost was calculated from protein turnover. Statistical analysis included Spearman correlations and partial correlation analyses.

RESULTS

Although body mass index was significantly lower for sickle cell versus controls (P < 0.02), children with asymptomatic sickle cell had 52% higher protein turnover (P < 0.0005). Proportional reticulocyte count, SynHb, MVO2 and resting energy expenditure were also significantly higher in children with sickle cell (P < 0.01). Protein turnover correlated significantly with both SynHb (r = 0.63, P < 0.01) and reticulocyte percentage (r = 0.83, P < 0.0001). Partial correlation of these 3 variables showed reticulocyte percentage as the only variable to be significantly associated with protein turnover, even after adjusting for sickle cell anemia (P = 0.03). Partial correlation of log resting energy expenditure on MVO2 was significant, controlling for protein energy cost, sex and age (P = 0.03).

CONCLUSION

These results indicate that metabolic demands of increased erythropoiesis and cardiac energy consumption account for much of the excess protein and energy metabolism in children with sickle cell anemia.

In vivo rates of erythrocyte glutathione synthesis in adults with sickle cell disease

Despite reports of lower GSH concentration in sickle cell disease (SCD), the in vivo kinetic mechanism(s) responsible for GSH deficiency is unknown. To determine whether suppressed synthesis was responsible for the lower erythrocyte GSH concentration, we used a primed intermittent infusion of [(2)H(2)]glycine to measure erythrocyte GSH synthesis in vivo in 23 individuals with homozygous beta(s) SCD and 8 healthy controls. Erythrocyte cysteine concentration, the rate-limiting precursor for GSH synthesis, plasma markers of oxidant damage, and dietary intakes of energy and protein were also measured. Compared with values of controls, SCD subjects had significantly lower erythrocyte GSH (P < 0.04) and cysteine concentrations (P < 0.004) but significantly faster fractional rates of GSH synthesis (P < 0.02). The absolute rates of GSH synthesis in SCD subjects compared with control subjects was greater by approximately 57% (P = 0.062). However, the concentrations of markers of oxidative damage, plasma derivatives of reactive oxygen metabolites, plasma nitrotyrosine, urinary isoprostane-to-creatinine ratio, and GSH-to-GSSG ratio, as well as dietary intakes of energy, protein, and GSH precursor amino acids, were not different between SCD subjects and controls. The findings of this study suggest that the lower erythrocyte GSH of SCD patients is not due to suppressed synthesis or impaired regeneration but rather to increased consumption. In addition, the lower erythrocyte cysteine concentration plus the faster rate of GSH synthesis strongly suggest that the endogenous cysteine supply is not sufficient to meet all anabolic demands; hence, cysteine may be a conditionally essential amino acid in individuals with SCD.

The end-product method of measuring whole-body protein turnover: a review of published results and a comparison with those obtained by leucine infusion

The present review summarizes the results of all published papers on whole-body protein turnover in man measured by [15N]glycine and the end-product method using both urea and ammonia. It begins with a short account of the underlying assumptions and the justification for the use of [15N]glycine. The results are then compared with those of a large sample of measurements by the 'gold standard' precursor method with continuous infusion of [13C]leucine. The pros and cons of the two methods are compared and it is suggested that there is a place for further work by the less invasive end-product method, particularly for population studies of the genetic, environmental and functional determinants of whole-body rates of protein synthesis.

Effect of long-term transfusion on growth in children with sickle cell anemia: results of the STOP trial

OBJECTIVE

To determine whether long-term transfusion improves growth in children with sickle cell anemia.

STUDY DESIGN

In the Stroke Prevention Trial for Sickle Cell Anemia Study, patients were randomized to receive long-term transfusion (CTX) or standard care (STC). Transfusions were administered every 3 to 5 weeks, and hemoglobin S levels were maintained at 30% pretransfusion for an average of 2 years. Serial height and weight measurements (obtained every 3 months), body mass index (BMI) values, and growth z-scores were analyzed.

RESULTS

Children in the CTX (n=53) and STC (n=41) groups were similar at baseline. After 24 months, the z-scores for height, weight, and BMI of those receiving CTX had improved significantly, whereas no changes occurred in the STC group. Patients in the CTX group approached normal height-for-age and weight-for-age z-scores. Patients from a large historical control group had significantly lower weight and height growth velocities than patients in the CTX group.

CONCLUSIONS

Patients in the Stroke Prevention Trial for Sickle Cell Anemia Study who received CTX had improved height and weight and BMI over a 2-year period. Higher hemoglobin levels resulting from transfusion may improve growth by lowering energy expenditure. In addition to the prevention of vasoocclusive events, CTX results in significant improvement in the growth of children with sickle cell disease.

Proinflammatory cytokines and the hypermetabolism of children with sickle cell disease

Sickle cell anemia (HbSS) includes chronic inflammation, but the origin is unclear. We hypothesized that in stable HbSS patients the inflammation was associated with hypermetabolism. We compared selected hypermetabolic and key immunomodulator indicators in HbSS versus control children and examined associations between measures of hypermetabolism and inflammation. Twelve fasting asymptomatic HbSS children 6-12 years and 9 controls matched for age, gender and fat mass (FM) were studied. Proportional reticulocyte count (retic%) and resting energy expenditure (REE) represented hypermetabolism, and C-reactive protein (CRP) indicated inflammation. Proinflammatory cytokines tumor necrosis factor-alpha (TNF-alpha) and interleukin-6 (IL-6), chemokine monocyte chemoattractant protein-1 (MCP-1), and energy balance cytokine leptin were measured. Methods were indirect calorimetry, enzyme-linked immunosorbent assay, and radioimmunoassay. Statistical analysis included simple correlation and regression analysis. REE (51 +/- 6 vs. 43 +/- 12 kcal/kg per fat-free mass (FFM), mean +/- SD), retic% (12 +/- 4 vs. 0.7 +/- 0.3%), CRP (5 +/- 3 vs. 0.3 +/- 0.4 mg/liter), and IL-6 (71 +/- 40 vs. 20 +/- 7 pg/ml) were significantly higher for HbSS than controls (P < 0.05). Conversely, leptin (0.1 +/- 0.1 vs. 2 +/- 1 microg/liter per kgFM) and MCP-1 (34 +/- 5 vs. 41 +/- 4 pg/ml) were significantly lower for the HbSS subjects (P < 0.01). TNF-alpha was not significantly different. There were no significant associations between REE or retic% and any cytokine measured. However, CRP was significantly associated with REE in HbSS (r = 0.8, P = 0.003) and an important predictor of REE/FFM. We provide new evidence for low circulating levels of inflammatory chemokine MCP-1 in stable HbSS children, confirm mostly low cytokine levels, inflammation, and hypermetabolism and demonstrate association of hypermetabolism with inflammation via CRP but not via cytokines.

Oral Glutamine Supplementation Decreases Resting Energy Expenditure in Children and Adolescents With Sickle Cell Anemia

OBJECTIVES

To determine the effects of orally administered glutamine on the resting energy expenditure (REE) and nutritional status of children and adolescents with sickle cell anemia.

METHODS

Twenty-seven children and adolescents (13 boys, 14 girls), 5.2 to 17.9 years old (median 11.0 years), received orally administered glutamine (600 mg/kg per day) for 24 weeks. Measures of REE and other nutritional parameters were compared at baseline and 24 weeks.

RESULTS

After 24 weeks, the patients' median REE (kcal/d) decreased by 6% (P = 0.053) as indicated by the Harris Benedict equations and by 5% (P = 0.049) as indicated by the modified equations. Patients with less than 90% ideal body weight had even greater declines in REE after 24 weeks (P < 0.03 and 0.02, respectively). Improvements in nutrition parameters and in two amino acids in the plasma were observed.

CONCLUSIONS

After 24 weeks of orally administered glutamine, children and adolescents with sickle cell anemia had a decrease in REE and improvement in nutritional parameters. Those who were underweight had a greater decrease in REE than those of normal body weight. Lowering REE may be an effective way to improve the growth of these children and adolescents.

Effect of a comprehensive clinical care program on disease course in severely ill children with sickle cell anemia in a sub-Saharan African setting

Clinical severity of sickle cell anemia (SS) in Africa may not be solely determined by genetic factors. This study evaluated the effects of intensive parental education and adequate clinical care on the course of SS in children in Benin. SS children referred to the National Teaching Hospital in Cotonou were included in the study. Teaching about SS was repeated frequently, emphasizing the importance of keeping clinic appointments, improving the nutrition of the affected children, and instituting antipneumococcal and antimalarial prophylaxis. Frequency and severity of SS-related events, changes in physical growth, frequency of malarial attacks, causes of transfusion, and causes of death were the principal variables assessed. 236 young children with repeated SS-related acute complications were studied from July 1, 1993, to December 31, 1999 (983 patient-years). A marked reduction in the frequency and severity of SS-related acute events was observed. Improvement in general status and physical growth was noted in 184 patients (78%); in addition, 22 of the remaining 52 patients showed similar improvement after remotivating the parents for compliance. There were 10 deaths, primarily in this cohort of 52 patients. Intensive sociomedical intervention can produce sustained clinical improvement in many severely ill SS children in sub-Saharan Africa.

Equation to estimate resting energy expenditure in adolescents with sickle cell anemia

BACKGROUND

Basal energy requirements are higher in adolescents with sickle cell anemia (SCA) than in healthy control subjects. However, no equation is available to accurately predict their energy needs.

OBJECTIVE

Our objective was to develop a clinically useful equation to estimate resting energy expenditure (REE) in adolescents with SCA.

DESIGN

REE and other components of total energy expenditure were measured in adolescents with SCA (n = 37) and in control subjects (n = 23) for 24 h in a whole-room indirect calorimeter. Multiple linear regression analysis was used to describe the relations of REE with independent variables such as sex, weight, height, fat-free mass, fat mass, age, and hemoglobin concentration in adolescents with SCA. The Bland-Altman comparison technique was used to compare values predicted by existing equations with measured REE values.

RESULTS

Mean (+/-SD) measured REEs were 7746 +/- 974 and 6332 +/- 869 kJ/d in the male and female subjects with SCA, respectively, and these values were 16% higher than those in the healthy control subjects. Standard equations underestimated REE by 12% (P </= 0.001) in adolescents with SCA and overestimated REE by 4% in control subjects (P = 0.01-0.29). Several REE regression equations for SCA were developed. The most parsimonious equation for males was REE (kJ/d) = 5461 + 77.7.weight (kg) - 233.2.hemoglobin (g/dL), or REE (kcal/d) = 1305 + 18.6.weight (kg) - 55.7.hemoglobin (g/dL). For females, the most parsimonious equation was REE (kJ/d) = 4603 + 55.6.weight (kg) - 126.2.hemoglobin (g/dL), or REE (kcal/d) = 1100 + 13.3.weight (kg) - 30.2.hemoglobin (g/dL).

CONCLUSION

The new equations have better agreement with the basal metabolic needs of adolescents with SCA than do standard predictive equations.

Vitamin B6 status of children with sickle cell disease

PURPOSE

In vitro, vitamin B(6) has antisickling properties, but the effect of vitamin B status on the health of children with sickle cell disease-SS (SCD-SS) is not well described. The purpose of this study was to assess vitamin B(6) status of children with SCD-SS ages 3 to 20 years and determine its relationship to growth, dietary intake, and disease severity.

PATIENTS AND METHODS

Vitamin B(6) status was assessed by serum pyridoxal 5-phosphate (PLP) concentration in subjects with SCD-SS and by urinary 4-pyridoxic acid (4-PA) concentration in other subjects with SCD-SS and healthy control children. Concentration of PLP was compared with anthropometric measures of growth and nutritional status, dietary intake, hematologic indices, and frequency of SCD-related illness.

RESULTS

The PLP concentration of subjects with SCD-SS was 15.6 +/- 15.2 nmol/L. Seventy-seven percent had a PLP concentration below the deficiency criterion (20 nmol/L) suggested by the Dietary Reference Intakes (1998). Controlling for alkaline phosphatase, age, and gender, PLP concentration was associated positively with weight, body mass index, and arm circumference -scores and negatively with reticulocyte count. Urinary 4-PA was lower in children with SCD-SS versus controls, although 4-PA/creatinine values did not differ between groups.

CONCLUSIONS

Children with SCD-SS had apparently low serum PLP concentrations in the absence of excess vitamin B(6) excretion, suggesting low vitamin B(6) status. Low serum PLP concentration was associated with indicators of poor nutritional status and may be related to increased hemolysis in children with SCD-SS.

Body composition in children with sickle cell disease

BACKGROUND

Impaired growth, poor nutritional status, and delayed skeletal and sexual maturation are common in children with sickle cell disease (SCD), yet the nature of associated body-composition deficits has not been fully described.

OBJECTIVE

The objective was to assess growth, nutritional status, and body composition in 36 African American children with type SS SCD (20 females and 16 males) and 30 healthy control children (15 females and 15 males) of similar age (5-18 y) and ethnicity.

DESIGN

Height, weight, bone age, pubertal status, skinfold thickness, and arm circumference were assessed. Height and weight were converted to z scores by comparison with national reference data and skinfold-thickness measurements were converted to z scores by comparison with African American- specific reference data. Fat-free mass (FFM) and fat mass (FM) were estimated by using 4 methods. Prepubertal children, pubertal males, and pubertal females were analyzed separately.

RESULTS

Relative to the control subjects and to a national sample, children with SCD had significantly lower z scores for weight, height, arm circumference, and upper arm fat and muscle areas. Relative skeletal maturation was significantly delayed. After adjustment for age, children with SCD had significantly lower FM (prepubertal children and pubertal males only) and FFM (all 3 groups).

CONCLUSIONS

Children with SCD have impaired growth, delayed puberty, and poor nutritional status. Low z scores for upper arm fat area indicate deficits in fat (energy) stores, and low FFM coupled with low upper arm muscle area indicate muscle wasting and low protein stores. These body-composition abnormalities suggest that the nutritional needs of the African American children with SCD were not being met.

Comparison of energy prediction equations with measured resting energy expenditure in children with sickle cell anemia

OBJECTIVE

To determine the accuracy of energy prediction equations when compared with measured resting energy expenditure (REE) in children with sickle cell anemia. To develop a modified equation that more accurately estimates the energy needs of children with sickle cell anemia and to cross-validate these on a different set of patients (test patients).

DESIGN

REE was measured in children using indirect calorimetry and compared with predicted values using the Harris-Benedict and the Food and Agriculture Organization/World Health Organization/United Nations University equations (WHO).

SUBJECTS/SETTING

Eighteen patients participated in the original sample that compared predicted with measured energy expenditure. The modified equations were developed using the original 18 patients. A test population of 20 different patients was used to validate the modified equations.

STATISTICAL ANALYSIS

Wilcoxon signed-rank test was performed to compare measured with predicted REE. The correlation analysis method and multiple linear regression method were used to develop 2 modified versions for the Harris-Benedict and WHO prediction equations.

RESULTS

When compared with the mean predicted REE using the Harris-Benedict and WHO equations, the mean measured REE was 14% and 12% greater than both (P=.005 and P=.014, respectively). Two modified equations were developed from the Harris-Benedict and WHO equations. Based on the data from the test patients, the mean measured REE was 15% greater than the mean predicted REE based on the Harris-Benedict and WHO equations (P=.0001 for both). When the modified Harris-Benedict and WHO equations were used, there was almost no difference in the mean measured REE and the mean predicted REE (mean difference using Harris-Benedict = 14, P = .9273; mean difference using WHO = -13, P = .6215).

CONCLUSION

Both energy prediction equations underestimated REE in children with sickle cell anemia. The 2 modified versions of the energy prediction equations that we propose predicted the energy needs of these children much more accurately; however, the modified equations need to be validated through application to other children with sickle cell anemia.

Bioelectrical impedance analysis of the body composition of children and adolescents with sickle cell disease

OBJECTIVES

To examine the body composition of children and adolescents with sickle cell disease (SCD) using bioelectrical impedance analysis and to determine if the impedance parameters resistance, reactance, and phase angle are able to distinguish between subjects with SCD and age- and gender matched controls.

STUDY DESIGN

Total body resistance and reactance were obtained for a total of 53 subjects with SCD (27 male and 26 female) between 10 and 18 years of age and 49 control subjects (23 male and 26 female). The fat-free mass, body cell mass, phase angle, and capacitance were also determined. Group comparisons were made using the 2-sample t test.

RESULTS

Male subjects with SCD had significantly lower fat-free mass (37.5 +/- 8.8 vs 43.9 +/- 12.3 kg, P =.04), body cell mass (17.4 +/- 4.3 vs 21.7 +/- 5.8 kg,P =.005), and body fat (3.7 +/- 2.6 vs 6.6 +/- 4.7 kg, P =.008) compared with controls. No significant differences in any body composition components were found for the female subjects. Both male and female subjects had significantly lower phase angle measurements (P <.001 and.006, respectively) than their respective controls, indicating possible alterations in cell membrane properties because of an imbalance in membrane composition or function.

CONCLUSIONS

Bioelectrical impedance analysis can be used to determine body composition differences in children with SCD. The phase angle may provide a useful method to monitor the efficacy of therapeutic interventions in patients with SCD.

Effect of hydroxyurea on growth in children with sickle cell anemia: results of the HUG-KIDS Study

OBJECTIVES

Although hydroxyurea is effective in treating adults with sickle-cell anemia (SCA), there is concern that it may adversely affect growth in children. We report the growth characteristics of patients in the Phase I-II pediatric hydroxyurea trial (HUG-KIDS) before and during treatment at the maximum tolerated dose for one year.

STUDY DESIGN

Children and adolescents with SCA (n = 68), aged 5 to 16 years at baseline, reached the maximum tolerated dose and had serial height, weight, and Tanner stage measurements. Data from the Cooperative Study of Sickle Cell Disease (CSSCD) were used for comparison. Mixed-effects models were used to compare serial measurements as a function of age and group.

RESULTS

In girls, there were no significant differences in height or weight among the pretreatment, on-treatment, and CSSCD groups. Compared with the CSSCD group, HUG-KIDS boys were heavier starting at age 9 years, and pretreatment HUG-KIDS boys were taller starting at age 7 years. The Tanner stage transitions took place at appropriate ages.

CONCLUSIONS

Hydroxyurea treatment had no adverse effect on height or weight gain or pubertal development in school-aged children with SCA.

Patterns and energy expenditure of free-living physical activity in adolescents with sickle cell anemia

OBJECTIVE

Our purpose was to examine the relationship between physical activity (PA), PA-associated energy expenditure (PAEE), and total daily energy expenditure (TEE) in free-living adolescents with sickle-cell anemia (SCA).

STUDY DESIGN

Adolescents with SCA (n = 28) were matched for sex and age with 22 healthy control participants. PA was measured for 6 to 8 consecutive days with a triaxial accelerometer and resting energy expenditure (REE) by whole-room indirect calorimetry. TEE was calculated by summing PAEE and REE.

RESULTS

TEE was similar, REE was higher (difference, 209 kcal x day(-1); P =.0001), and PAEE was lower (difference, 657 kcal x day(-1); P <.001) in patients with SCA than in control participants. In SCA, there was a positive linear relationship between PAEE and hemoglobin concentration (r (2) = 0.583). Time spent in PA of moderate and high intensity was lower in patients with SCA than in control participants (18 +/- 22 vs 48 +/- 31 min/d; P <.0001).

CONCLUSION

In adolescents with SCA under free-living conditions, there is a significant intra and interindividual variability in the amount of PA, PAEE, and PA patterns. Because of a lower PAEE and a higher REE, TEE is similar in adolescents with SCA and healthy adolescents. An association of PAEE with hemoglobin concentration may be a part of an energy saving compensatory mechanism in SCA.

Energetic cost of protein turnover in healthy elderly humans

OBJECTIVE

Whole body protein turnover (PTO) and resting energy expenditure (REE) are both correlated to fat-free mass (FFM), in young and elderly subjects, and REE is positively correlated to PTO in young adults. Thus, the aim of this study was to compare the energetic cost of PTO in young (n=39, 23.4+/-3.1 y) and elderly (n=41, 67.5+/-3.6 y) healthy volunteers.

MEASUREMENTS

REE (indirect calorimetry), PTO ((13)C-leucine isotopic dilution) and body composition (bioelectrical impedance analysis with age-specific equations) were measured in the postabsorptive state.

RESULTS

Elderly subjects had a higher fatness (30.5+/-7.1 vs 18.2+/-5.5%, elderly vs young, P<0.001), a similar REE (0.97+/-0.13 vs 1.06+/-0.15 kcal min(-1)), and a lower PTO (1.28+/-0.22 vs 1.44+/-0.18 micromol kg(-1) min(-1), P<0.001). PTO, REE and FFM were significantly correlated and after adjustment for FFM, REE was positively correlated to PTO (r=0.61, P<0.001). The slope of this relationship was the same in both groups, while the adjusted mean REE was lower in elderly subjects (0.97+/-0.09 vs 1.05+/-0.07 kcal min(-1), P<0.01).

CONCLUSION

In comparison with young subjects, the energetic cost associated with PTO in elderly subjects is not different, but the proportion of REE not associated with PTO is lower.

Measurement of hemoglobin synthesis rate in vivo using a stable isotope method

We developed a method to measure hemoglobin synthesis rate (SynHb) in humans, assuming that free glycine in the red blood cell (RBC) represents free glycine in bone marrow for hemoglobin synthesis. The present rat study examines this assumption of the method and quantifies SynHb in rats. Sprague-Dawley rats (n = 9) were studied, [2-(13)C]glycine was intravenously infused over 24 h (2.5 mg kg(-1) h(-1)), blood was drawn for glycine and heme isolation, and bone marrow was harvested for glycine isolation. Isotopic enrichments of glycine and heme were measured, fractional hemoglobin synthesis rate (fSynHb% day(-1)) was calculated, and from this a value for SynHb (mg g(-1) day(-1)) was derived. Mean body weight was 446 +/- 10 g (mean +/- SE) and hemoglobin concentration was 14 +/- 0.5 g dl(-1). At 24 h, the mean isotopic enrichment, atom percentage excess (APE), of the RBC free glycine (1.56 +/- 0.18 APE) was similar to the bone marrow (1.68 +/- 0.15 APE). The rate of incorporation of (13)C into heme increased over time from 0.0004 APE/h between 6 and 12 h, to 0.0014 APE/h between 12 and 18 h, and 0.0024 APE/h between 18 and 24 h. Consequently, fSynHb (1.19 +/- 0.32, 2.92 +/- 0.66, and 4.22 +/- 0.56% day(-1), respectively) and SynHb (0.11 +/- 0.03, 0.28 +/- 0.05, and 0.42 +/- 0.05 mg g(-1) day(-1), respectively) showed similar patterns over the 24-h study period. We conclude that (1) enrichment of free glycine in the circulating RBC approximates enrichment of bone marrow free glycine for heme formation and (2) this pattern of hemoglobin synthesis rate is reflecting the characteristic release and gradual maturation of reticulocytes in the circulation.

Energy expenditure and intake in children with sickle cell disease during acute illness

BACKGROUND

Children with sickle cell disease have frequent bouts of pain and infection which may increase energy expenditure, decrease energy intake and lead to a subsequent energy deficit.

METHODS

Two groups of African-American children with sickle cell disease-SS genotype were enrolled in this study upon hospital admission for a sickle cell disease related illness: a younger (<6 years, n=14, 7 M) and older group (> or =6 years, n=17, 8 M). Body composition and dietary intake were assessed, and sleeping (younger) or resting energy expenditure (older) were measured by indirect calorimetry at admission and one month later at steady state.

RESULTS

Energy expenditure was not different between the two timepoints for younger children, but was slightly elevated at steady state (+50 kcal/d, P=0.049) in the older group. After controlling for gender, changes in fat-free mass and dietary intake, the significance disappeared. Energy intake in both groups was significantly depressed at admission compared to follow-up (P<0.01).

CONCLUSIONS

These children and adolescents did not expend excess energy during their acute illness, however, an energy deficit was observed secondary to poor energy intake. Since 20% of patients with sickle cell disease have multiple hospitalizations per year, these results provide justification for the development and evaluation of nutrition care protocols to maintain adequate caloric intake during hospitalization and recovery.

Increased bone turnover is associated with protein and energy metabolism in adolescents with sickle cell anemia

Contribution of bone turnover to the hypercatabolic state observed in sickle cell anemia is unknown. We examined the association between markers of bone turnover and basal rates of whole body protein turnover and energy expenditure in 28 adolescents with homozygous sickle cell anemia (HbSS) and in 26 matched controls with normal phenotype (HbAA). Whole body protein breakdown and synthesis were measured using a stable isotope of [15N]glycine, resting energy expenditure was measured by whole room indirect calorimetry, and the rate of pyridinoline cross-link (PYD) excretion in urine and fasting serum levels of the type I procollagen carboxy-terminal propeptide (PICP) were measured with commercial kits. Urinary PYD and serum PICP were significantly elevated in HbSS patients. The increase in procollagen synthesis, indicated by high levels of PICP, was significantly correlated with increased whole body protein synthesis. The increase in type I collagen degradation, indicated by high PYD excretion, was significantly correlated with increased protein breakdown. We conclude that increased rates of bone turnover contribute to the increased rates of protein turnover and energy expenditure observed in adolescents with homozygous sickle cell anemia.

Glutathione in disease

Altered glutathione metabolism in association with increased oxidative stress has been implicated in the pathogenesis of many diseases. However, whether strategies aimed at restoring glutathione concentration and homeostasis are effective in ameliorating or modifying the natural history of these states is unknown. In this review we discuss the pathogenic role for altered glutathione metabolism in such diseases as protein energy malnutrition, seizures, Alzheimer's disease, Parkinson's disease, sickle cell anaemia, chronic diseases associated with ageing and the infected state. In addition, we discuss the efficacy of glutathione precursors in restoring glutathione homeostasis both in vitro and in vivo.

Plasma leptin association with body composition and energy expenditure in sickle cell disease

OBJECTIVE

To examine the association between fasting plasma leptin concentrations and the hypercatabolic state observed in sickle cell disease (SCD).

METHODS

Plasma leptin concentration and resting energy expenditure (REE) were measured in 37 SCD patients (10 men, 12 boys 14 to 18 years-old, seven women, and eight girls 14 to 18 year-old) and in 37 age, gender and fat mass (FM) matched controls. Body composition was measured hydrostatically, REE by whole room-indirect calorimeter, and plasma leptin using an RIA kit.

RESULTS

Plasma leptin concentration and leptin normalized for body fat (ng/dL*kg FM(-1)) were significantly lower in SCD patients than in non-SCD controls (4.00+/-3.23 vs. 9.94+/-14.69, p=0.021 and 0.406+/-0.260 vs. 0.643+/-0.561, p=0.024, respectively). A positive linear association between log plasma leptin and FM was observed in both males and females, adjusting for age and SCD status. The strength of this association was greater in females compared with males (slope=0.699 and 0.382 log ng/mL per 10 kg FM, respectively; p=0.013). SCD patients on average demonstrated a higher REE, adjusting for FFM (p<0.0001). Log plasma leptin and FM were not statistically significant predictors of REE after adjustment for FFM and SCD.

CONCLUSIONS

Once corrected for body composition, mean plasma leptin concentration was significantly lower among female SCD patients than among non-SCD matched controls. Although REE was higher in SCD patients, there is no simple association between leptin and REE in SCD.

Impact of acute illness on nutritional status of infants and young children with sickle cell disease

OBJECTIVE

To evaluate changes in growth, nutritional status, body composition, and energy and nutrient intakes during illness and usual state of health in infants and young children with sickle cell disease.

DESIGN

Sixteen children, aged 0.4 to 5.6 years, with SS type sickle cell disease (SCD-SS) were assessed at the time of hospital admission for an acute illness episode and during an 18-hour overnight follow-up visit 2 to 6 weeks after the acute illness episode when in a state of usual health. Main outcome measures included growth in height and weight compared with reference standards, body composition determined by the skinfold thickness technique and total body electrical conductivity, and dietary intake determined by 24-hour recall during hospital admission and at follow-up.

RESULTS

Height, weight, and weight-for-height z scores did not differ from national reference data; triceps skinfold thickness and arm fat area z scores were less. Mean +/- standard error body fat was 15.6 +/- 2.1% at the time of hospital admission, as measured by total body electrical conductivity, and was not significantly different from the follow-up value (16.2 +/- 2.2%). Mean energy intake was 44 +/- 9% of Recommended Dietary Allowances at the time of admission and differed significantly from the follow-up value of 90 +/- 9% (P < .05).

APPLICATIONS

Infants and children with sickle cell disease appear to be at nutritional risk during an acute illness episode, as indicated by body fat measures and inadequate intakes of energy and macronutrients. Energy intake may be suboptimal for several days surrounding an admission for an acute illness in children with sickle cell disease. Physicians and other health practitioners should be alert to inadequate nutrient intakes of their patients during this time period and may consider supplemental energy to avoid a potential net negative energy balance.

Total and resting energy expenditure in children with sickle cell disease

OBJECTIVE

To investigate energy balance in children with sickle cell disease (SCD) as the possible cause of impaired growth and undernutrition.

STUDY DESIGN

Growth, resting (REE), total (TEE), and activity-related (AEE) energy expenditure and dietary intake were examined in 36 African American children with SCD (20 girls and 16 boys) and 30 control subjects (15 girls and 15 boys) of similar age (mean, 11.2 years) and ethnicity. TEE was measured by means of the doubly labeled water technique and REE by indirect calorimetry. AEE was calculated as TEE minus REE. Fat free mass (FFM) was calculated from skinfold prediction equations.

RESULTS

REE was significantly increased (131 kcal/d) in children with SCD (P =.001), after adjusting for sex and FFM. Children with SCD tended to have lower TEE (214 kcal/d) than control subjects, but there was no difference after adjusting for FFM and sex (P =.57). Children with SCD had significantly (P =.025) lower AEE (268 kcal/d) but only marginally (P =.08) lower AEE after adjusting for FFM and sex.

CONCLUSIONS

The elevated REE and lower AEE, in combination with poor growth status, indicate chronic energy deficiency in children with SCD. Further studies are needed to determine the best approaches to the treatment and prevention of undernutrition in children with SCD.

Whole body protein turnover in children with human immunodeficiency virus (HIV) infection

The purpose of this study was to determine the rate of whole body protein turnover (WBPT) in human immunodeficiency virus (HIV)-infected children, and to determine the relationship between WBPT and growth. The rate of WBPT was calculated from the cumulative excretion of labeled urinary ammonia after a single intravenous dose of 15N-glycine in three groups of children: 1) HIV+ with growth retardation (HIV+ Gr); 2) HIV+ with normal growth (HIV+); and 3) HIV-uninfected with normal growth (HIV-). Twenty-six children between 2 and 11 y of age were studied (10 HIV+ Gr, 12 HIV+, 4 HIV-). All children were afebrile and free of acute infection during the study. Rates of WBPT (mean +/- SD) for the study groups were: HIV+ Gr, 12.2 +/- 4.8; HIV+, 10.7 +/- 5.1; and HIV-, 8.6 +/- 2.1 g.protein.kg-1.d-1 (NS, P > 0.05). Although not statistically significant, mean WBPT was 42% greater in HIV+ Gr, and 24% greater in HIV+ compared to HIV-. Statistically significant correlations were found between WBPT and Z scores for height (r = -0.39, P = 0.05) and weight-for-age (r = -0.51, P = 0.01) and dietary intake of protein (r = 0.39, P = 0.05), and between protein balance (synthesis-catabolism) and intakes of energy (r = 0.47, P = 0.02) and protein (r = 0.40, P = 0.04). There was no statistically significant correlation between WBPT and resting energy expenditure (r = 0.27, P = 0.19), or CD4 cell number (r = 0.05, P = 0.82). These data suggest an association between increased rates of protein turnover and low weight and height-for-age Z scores, and that it may be possible to achieve positive protein balance given an adequate intake of nutrients.

Elevated resting energy expenditure in adolescents with sickle cell anemia

OBJECTIVE

To assess the reliability of standard prediction equations in estimating resting energy expenditure (REE) values in adolescents with sickle cell anemia.

SUBJECTS/DESIGN

Body composition and metabolic measurements were performed in 8 adolescents, aged 11 to 18 years, with homozygous sickle cell anemia. REE was measured by indirect calorimetry under standard conditions, and measurements were compared with 4 prediction formulas (Harris-Benedict, Schofield, Mayo Clinic, and Food and Agriculture Organization/World Health Organization/United Nations University). Fat-free mass was measured to assess REE per unit of actively metabolizing tissue. Fat-free mass was expressed as a mean of values obtained by densitometry, deuterium dilution, 40K-counting, and total body electrical conductivity.

STATISTICAL ANALYSES

Repeated measures analysis of variance was performed to determine whether measured REE values and predicted values differed. The Fischer test was used to identify which predicted values differed significantly from the measured REE.

RESULTS

All 4 prediction formulas significantly underestimated REE. Group mean values for the prediction formulas ranged from 83% to 89% of the measured value. REE averaged 47.7 +/- 10.0 kcal/kg fat-free mass per day, which is 30% to 50% higher than reported values in healthy adolescent populations.

CONCLUSIONS

These data suggest that REE is elevated in adolescents with sickle cell anemia. Standard equations used to predict REE are unreliable in these patients.

APPLICATIONS

REE in patients with sickle cell anemia is best determined by indirect or direct measurement of energy expenditure. Clinically useful formulas to estimate REE should be developed for patients with conditions, including sickle cell anemia, where the metabolic rate may be altered.