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Biomedical subjects

S A Atkinson

Publications and source records attributed to S A Atkinson.

At least 19 recordsLinked to original sources
PubMed2005

Alendronate for steroid-induced osteopenia in children with acute lymphoblastic leukaemia or non-Hodgkin's lymphoma: results of a pilot study.

BACKGROUND/OBJECTIVES: Osteopenia is a significant morbidity in children undergoing therapy for acute lymphoblastic leukaemia (ALL) or non-Hodgkin's lymphoma (NHL). We conducted a pilot study to assess the impact of alendronate on whole body bone mineral content (WB-BMC), lumbar spine bone mineral density (LS-BMD), biochemical measures of bone mineral metabolism, as well as gross motor function and health-related quality of life (HRQL) in children undergoing therapy for ALL or NHL. METHODS: Ten children (nine boys) between the ages of 3.6 and 14.6 years, on identical maintenance chemotherapy for ALL or NHL were treated with oral alendronate once weekly, and daily calcium supplementation, for a period of six months. Outcome measures were WB-BMC and LS-BMD; biochemical measures of bone mineral metabolism including plasma osteocalcin, C-terminal telopeptide of type I collagen (CTx), serum calcium, 25-hydroxy-vitamin D (25-OHD), and parathyroid hormone (PTH); as well as assessments of motor function and HRQL. RESULTS: A gain in Z score was observed in 7/9 evaluable patients for WB-BMC (mean increase of 0.49) and LS-BMD (0.51). Plasma osteocalcin and CTx showed a change in bone turnover favouring formation over resorption. Serum calcium and 25-OHD remained normal throughout treatment. After an initial spike, serum PTH returned to baseline values at week 4. Measures of motor function showed some improvement and there were modest gains in HRQL. CONCLUSIONS: Alendronate therapy was tolerated well. Further study in a larger sample of children with ALL or NHL is warranted, in the context of a randomized clinical trial.

Absorptiometry, Photon↗
PubMed2001

Randomized trial of breastfeeding support in very low-birth-weight infants.

OBJECTIVE: To determine if supplementary structured breastfeeding counseling (SSBC) for both parents compared with conventional hospital breastfeeding support (CHBS) improves the duration of breastfeeding in very low-birth-weight infants up to 1 year old. DESIGN: Randomized trial with longitudinal follow-up of infants at term, and ages 1, 3, 6, and 12 months (infant ages corrected for prematurity). SETTING: A tertiary-level neonatal intensive care unit (NICU) and geographically defined region in central-west Ontario, Canada. PARTICIPANTS: Parents of infants with a birth weight less than 1500 g, who planned to breastfeed. INTERVENTIONS: The SSBC consisted of viewing a video on breastfeeding for preterm infants; individual counseling by the research lactation consultant; weekly personal contact in the hospital; and frequent postdischarge contact through the infants' first year or until breastfeeding was discontinued. The CHBS group had standard breastfeeding support from regular staff members confined to the period of hospitalization in the NICU. MAIN OUTCOME MEASURE: Duration of breastfeeding. RESULTS: At study entry, there were no statistically significant differences in major demographic characteristics between groups. The mean duration of breastfeeding was 26.1 weeks (SD = 20.8; median, 17.4) in the SSBC group and 24.0 weeks (SD = 20.5; median, 17.4) in the CHBS group (not statistically significant). CONCLUSIONS: Long-term breastfeeding counseling of parents of very low-birth-weight infants in this study did not demonstrate a significant difference in duration of breastfeeding. These results may be explained by the high motivation to breastfeed in both groups, a relatively advantaged population, and the availability of community breastfeeding resources, which may have diminished any significant differences that could have resulted from a breastfeeding intervention. The results of this study, compared with previous studies of very low-birth-weight infants, indicate a new trend to longer duration of breastfeeding in preterm infants.

Adult↗
PubMed2001

Magnesium absorption using stable isotope tracers in healthy children and children treated for leukemia.

Intestinal magnesium (Mg) absorption was measured in six healthy children (control) and in four children treated for acute lymphoblastic leukemia with the single-isotope fecal recovery technique (SIFRT). The objective of this study was to determine Mg absorption in young children with acute lymphoblastic leukemia using stable isotope tracers. Fractional and absolute absorption levels determined by SIFRT were not significantly different between children with acute lymphoblastic leukemia (fractional absorption: 58.3 +/- 10.6% [mean +/- SEM], absolute absorption: 3.66 +/- 0.71 mg x kg(-1) x d(-1), [0.15 +/- 0.03 mmol x kg(-1) x d(-1)]) and control children (fractional absorption: 61.4 +/- 7.5%, absolute absorption: 5.69 +/- 0.85 mg x kg(-1) x d(-1), [0.23 +/- 0.03 mmol x kg(-1) x d(-1)]). Average Mg absorption in young children (aged 3--8 y) was 60.2 +/- 5.8%. This study describes the first application of the SIFRT to assess Mg absorption in young children and illustrates the feasibility of the SIFRT in this age group to obtain more accurate information on Mg absorption.

Case-Control Studies↗
PubMed2001

Long-term valproate and lamotrigine treatment may be a marker for reduced growth and bone mass in children with epilepsy.

PURPOSE: To determine whether long-term treatment with valproate (VPA) and/or lamotrigine (LTG) in children with epilepsy is associated with altered growth and/or bone metabolism. METHODS: Twenty-seven boys and 26 girls, aged 3 to 17 years (9.2 +/- 3.9, mean +/- SD), with epilepsy treated with VPA and/or LTG for > or =2 years were evaluated for growth, nutrient intakes, physical activity, bone mineral density (BMD), and blood biochemical indices of mineral and bone metabolism. RESULTS: Twenty-three (43.4%) of the children had a body height below the 10th percentile. Z-scores for BMD below -1.5 occurred in 24.4% of the children. When patients were divided into two groups according to daily activity score, a significantly lower Z-score for total body BMD (p = 0.007), percentile for body height (p = 0.05), and plasma parathyroid hormone (PTH; p = 0.04), osteocalcin (p = 0.04) and 25-hydroxyvitamin D (25OHD) (p = 0.01) were found in the inactive compared with the active group. Z-score for total body BMD was correlated with daily activity score (r = 0.43, p = 0.008). Plasma intact osteocalcin and intact PTH values correlated significantly (r = 0.36, p = 0.02). Plasma 1,25-dihydroxyvitamin D was within normal range for all subjects. When patients were divided into LTG-alone, VPA-alone, and LTG-plus-VPA treatment groups, significantly lower (p < 0.05) plasma osteocalcin and percentile for body height were found in the VPA-plus-LTG treatment group. CONCLUSIONS: Long-term VPA and LTG therapy, particularly when combined, is associated with short stature, low BMD, and reduced bone formation. These alterations may be mediated primarily through reduced physical activity rather than through a direct link to the VPA and/or LTG therapy.

Adolescent↗
PubMed2001

Special nutritional needs of infants for prevention of and recovery from bronchopulmonary dysplasia.

Extremely low birth weight infants who develop severe respiratory disease may have special nutrient requirements imposed by a combination of enhanced utilization of nutrients or the need for epithelial cell repair resulting from the disease process, as well as to support catch-up growth. Inositol, free fatty acids, vitamin E and vitamin A are proposed as nutrients for which infants at risk of chronic pulmonary insufficiency may have special requirements. Of these nutrients, only for vitamin A does suggestive evidence exist that high doses when given intramuscularly may reduce the incidence of death or chronic lung disease. Exogenous steroid therapy (dexamethasone), which is often used to improve pulmonary compliance in ventilated premature infants, may compromise vitamin A status and induce restricted somatic and bone mineral growth. Supplemental nutrition by means of enriched infant formulas has provided benefits in growth and bone mass accretion to infants recovering from bronchopulmonary dysplasia up to 3-mo corrected age. This growth advantage was not sustained over the subsequent 9 mo, suggesting that prolonged nutritional support is required until catch-up growth is complete. Further studies are required to delineate the needs for specific nutrients such as antioxidant vitamins and minerals or vitamin A that may play a role in preventing severe chronic lung disease in premature infants. As well, the role of supplemental nutrition (beyond the requirements of term infants) to support catch-up growth and maintenance during the critical stages of early development requires further investigation before evidence-based nutrient recommendations can be developed for this special population of infants.

Bronchopulmonary Dysplasia↗
PubMed2001

Elevated intact parathyroid hormone is associated with reduced biochemical markers of bone formation and resorption measured in blood in infant piglets receiving oral dexamethasone for 15 days.

Seven-day-old male Yorkshire piglets were randomized to receive either dexamethasone (DEX) 0.5 mg/kg/day or placebo (water) for 15 days (n = 8/group). Body weight and length, plasma intact parathyroid hormone (PTH), N-Mid osteocalcin and C-terminal telopeptide of type I collagen (CTx) were measured at baseline and end of the study. The indices of bone metabolism did not differ between DEX and placebo groups at baseline. At the end of the study, plasma intact PTH was increased (p < 0.01) and N-Mid osteocalcin (p < 0.01) and CTx (p < 0.01) were decreased from baseline value in the DEX group but not in the placebo group. The reduction (Z-score) in N-Mid osteocalcin was greater than that in CTx (p < 0.05). We conclude that exogenous DEX in young piglets stimulates a rise in circulating intact PTH. Both circulating CTx and osteocalcin are reduced with the decline in osteocalcin greater than that in CTx.

Animals↗
PubMed2000

Human milk feeding of the micropremie.

There is increasing evidence that mother's milk is an appropriate feeding even for LBW and VLBW infants. During early neonatal life, supplements in the form of human milk fortifiers or single nutrients may be necessary to maintain an adequate biochemical status especially for sodium, phosphorus, and protein. The ideal amount and balance of supplemental nutrients to add to mother's milk for small premature infants remain unknown. From research to date, it is clear that growth responses to fortified mother's milk fed in early life may not be the most important outcomes in relation to long-term growth and development. Infants who receive human milk in early life may be at reduced risk for developing infections and allergy as well as osteopenia and growth failure. Further studies are needed to provide a better understanding of the role of human milk as the sole source of nutrition in premature infants, especially the micropremie.

Humans↗
PubMed2000

Factors influencing body composition of premature infants at term-adjusted age.

We investigated the influence of body size at birth, feeding of mother's milk versus formula, or standard-term formula versus energy- or nutrient-enriched formula on the growth and whole body bone mineral content (BMC), lean and fat mass (using dual-energy X-ray absorptiometry) of low-birth-weight (LBW) infants to term-adjusted age. LBW infants who were appropriate for gestational age were lighter and shorter than term-born infants (n = 46) but had a higher percent fat mass (19-28% vs. 15 +/- 7%). For LBW infants fed standard formula or mother's milk after hospital discharge, the mean BMC expressed either as a function of weight (17 +/- 2, 19 +/- 2 vs. 20 +/- 2 g/kg) or length (1.1 +/- 0.2, 1.1 +/- 0.2 vs. 1.5 +/- 0.2 g/cm) was more than 1 SD below term infant values. However, infants fed a nutrient-enriched formula from hospital discharge had BMC within 1 SD below term infants. Infants who were born small, compared to appropriate for gestational age, compared to infants of similar birth weight had lower percent body fat (16 +/- 6 vs. 19 +/- 5) and lower BMC (47 +/- 3 vs. 62 +/- 5 g) at term age. Both size at birth and diet influence patterns of growth and body composition in early life in very-low-birth-weight (VLBW) infants. The long-term significance of these variable growth patterns in VLBW infants in early life requires further investigation.

Adipose Tissue↗
PubMed1999

Bone metabolism and circulating IGF-I and IGFBPs in dexamethasone-treated preterm infants.

AIM: To characterize the ontogeny of circulating IGF-I, the IGF binding proteins (IGFBPs) and biochemical markers of bone turnover in dexamethasone (DEX)-treated preterm infants with chronic lung disease. METHODS: Plasma and urine samples from 17 infants were obtained prior to DEX, after 9-12 days of DEX and 10 days after the completion of DEX to assess plasma IGF-I, IGFBPs, osteocalcin and urinary N-telopeptide. Nutrient intakes and growth were monitored from birth until term corrected age at which time body composition was evaluated by dual energy X-ray absorptiometry. RESULTS: Although nutrient intakes did not differ during or after DEX, weight gain (115 vs. 174 g/week) and length gain (0.7 vs. 1.0 cm/week) were higher after DEX treatment. Plasma IGF-I, IGFBP-3 and osteocalcin increased over time. N-telopeptide was the only biochemical parameter which appeared to be suppressed during DEX (1342 nM bone collagen equivalents/mM creatinine vs. 2486 (pre-DEX) and 2292 (post-DEX)). At term corrected age, bone mineral content was lower in dexamethasone-treated infants compared to preterm and term reference infants. CONCLUSION: Changes in circulating IGFBP-2 and IGFBP-3 paralleled the changes reported in non-steroid-treated infants; however, it remains uncertain whether the natural rise in IGF-I was suppressed by DEX treatment. Assessment of these circulating components provided limited insight into the mechanisms by which DEX alters growth and bone turnover.

Absorptiometry, Photon↗
PubMed1999

Effects of nutrients in human milk on the recipient premature infant.

As the rate of survival of premature infants is increasing, more attention is necessarily focused on improving the quality of survival through optimal nutritional management. The nutritional needs of the premature infant are greater than at any other time in the life cycle. The benefits of human milk for term infants are well known. Emerging data suggest that human milk may especially benefit the premature infant. The human milk-fed premature infant may experience improved health (such as lower rates of infection and necrotizing enterocolitis), gastrointestinal function, and neurodevelopment. These factors may outweigh the concerns about adequate growth, nutrient accretion, and biochemical indices of nutritional status attributed to the lower nutrient content of human milk compared with preterm formula. Some of the nutritional concerns may be met by the use of multinutrient supplements during the time infants receive tube-feeding, generally the time prior to attaining complete oral feeding in-hospital. The available data suggest that the quality of survival of premature infants can be improved, both in the short-term and long-term, through the feeding of human milk.

Breast Feeding↗
PubMed1999

Calcium does not inhibit iron absorption or alter iron status in infant piglets adapted to a high calcium diet.

The purpose of this study was to investigate whether a dietary calcium:iron ratio similar to that often consumed by premature human infants inhibits iron absorption in infant piglets adapted to a high calcium diet. Male Yorkshire piglets were randomized at 3 to 4 d of age to a high calcium diet (4.67 g/L = HC) or a normal calcium diet (2.0 g/L = NC) and fed for 2 to 2.5 wk. An iron dextran injection was administered in amounts to achieve a marginal state of iron repletion to simulate iron status of premature infants. In vivo iron absorption from the diet was determined using the radiotracers 55Fe and 59Fe and whole body counting. Calcium:iron interactions at absorption sites in piglets fed HC and NC were investigated by measurements of time-dependent 59Fe uptake in response to different calcium:iron ratios in vitro in brush border membrane vesicles (BBMV). In vivo iron absorption from the diet did not differ between NC and HC diet groups [57 +/- 8% versus 55 +/- 17% (mean +/- SD), respectively]. Iron status and iron contencentrations in spleen, liver, intestine, kidney and heart did not differ between diet groups. Iron uptake in BBMV was significantly reduced by calcium in both HC and NC (P < 0.001); but there were no significant differences in iron uptake in response to different calcium:iron ratios between HC and NC. With feeding a HC diet for 2 wk there may be an adaptive response to counteract the inhibitory effects of calcium on iron absorption, thus resulting in similar in vivo iron absorption and iron status irrespective of the 1.3-fold difference in dietary calcium:iron ratio between piglet groups. However, future studies are needed to determine the specific sites of calcium:iron interactions and adaptation mechanisms. Since the calcium:iron ratios used in this study reflect the usual calcium:iron ratios in diets for premature infants, it is unlikely that interactive effects of calcium with iron will compromise iron status in this infant population when diets are supplemented with calcium.

Animals↗
PubMed1999

Growth hormone and insulin-like growth factor-I therapy promote protein deposition and growth in dexamethasone-treated piglets.

BACKGROUND: Dexamethasone treatment facilitates the weaning of premature infants from mechanical ventilation but impairs protein homeostasis, lean tissue deposition, and growth. The current study was conducted to investigate whether dexamethasone mediates these effects by reducing protein synthesis or elevating protein breakdown, and whether adjuvant growth hormone+/-insulin-like growth factor-I therapy can attenuate such effects. METHODS: Piglets (n = 24) were randomized to placebo, a tapered course of dexamethasone (0.5, 0.3, 0.2 mg/kg per day for 5, 5 and 4 days each, respectively), dexamethasone + growth hormone 0.1 mg/kg per day, or dexamethasone + growth hormone + insulin-like growth factor-I 0.1 mg/kg per day for 14 days. On day 13, 15N-glycine was administered as a single oral dose, and urine was collected at timed intervals during the subsequent 48 hours. RESULTS: Total urinary N and cumulative 15N excretion were higher in all dexamethasone groups than in control subjects. Protein synthesis was suppressed, whereas protein breakdown was unaltered by dexamethasone. Adjunctive growth hormone+/-insulin-like growth factor-I therapy enhanced protein synthesis, but only combined therapy improved net protein gain compared with dexamethasone alone. Higher circulating insulin-like growth factor-I may have mediated the greater net protein gain. Blood urea nitrogen was elevated in all dexamethasone-treated groups at days 6 and 11 but was normalized by day 15 with adjunctive growth hormone+/-insulin-like growth factor-I. From a functional perspective, both adjunctive growth hormone and growth hormone+/-insulin-like growth factor-I partially attenuated the dexamethasone-induced reduction in weight and length gain but not in whole body lean and fat mass. CONCLUSION: Adjunctive growth hormone+/-insulin-like growth factor-I therapy partially reverses the dexamethasone-induced reduction in protein synthesis, resulting in improved growth when given concurrently with a low tapering dose of dexamethasone.

Animals↗
PubMed1998

Growth and body composition in infants with bronchopulmonary dysplasia up to 3 months corrected age: a randomized trial of a high-energy nutrient-enriched formula fed after hospital discharge.

OBJECTIVES: (1) To determine whether nutrient malabsorption or inadequate nutrient intake were involved in the cause of growth delay in patients with bronchopulmonary dysplasia, and (2) to determine whether a nutrient-enriched formula given to infants with bronchopulmonary dysplasia to 3 months corrected age improves the rate of growth with greater lean and bone mass accretion when compared with infants fed an isoenergetic standard infant formula. STUDY DESIGN: A blinded, nutrition intervention trial of 60 preterm infants with bronchopulmonary dysplasia (birth weight, 866 +/- 169 g, gestational age, 26 +/- 1.5 weeks) randomized to either nutrient-enriched formula or standard formula. Growth, body composition, and nutrient retention were compared between groups by Student's t tests and analysis of covariance. RESULTS: Infants fed the enriched formula had significantly greater nitrogen and mineral retention at 38 weeks' postmenstrual age, and only the infants fed enriched formula had zinc retention similar to the intrauterine accretion. At 3 months corrected age infants fed enriched formula attained greater length (P < .05), greater radial bone mineral content (P < .01), and greater lean mass (P < .01). The male infants in the enriched formula group had greater whole body bone mineral content than did male infants in the standard formula group (P = .02). CONCLUSIONS: Greater linear growth and lean and bone mass in the enriched formula group suggests that infants with bronchopulmonary dysplasia attain faster "catch-up" growth when fed higher intakes of protein, calcium, phosphorus, and zinc than provided in standard proprietary formulas.

Analysis of Variance↗
PubMed1998

Growth and body composition of preterm infants: influence of nutrient fortification of mother's milk in hospital and breastfeeding post-hospital discharge.

We examined the influence of multi-nutrient fortification of mother's milk (MM + MNF) compared to supplementation with calcium and phosphorus (MM + CaGP) alone in hospital (in a randomized trial), and of breastfeeding (post-MM) compared to formula feeding (post-FF ) after hospital discharge with a descriptive analysis of growth and body composition to 1 y corrected age in preterm infants. Anthropometry, nutrient intakes and whole body bone mineral content, lean and fat mass were determined at four time points in the first year after term corrected age. Body composition was determined with dual energy X-ray absorptiometry. MM + MNF compared to MM + CaGP for preterm infants in the early neonatal period did not appear to influence growth or body composition in the first year. Growth in post-MM and post-FF groups was within the normal range of growth references derived from term infants fed mother's milk. Post-MM infants had lower whole body bone mineral content (132.3 +/- 10.4 g) at 6 months corrected age when compared to post-FF infants (159.4 +/- 14.1 g) and greater percent fat mass to 12 months corrected age. These differences may result from the lower calcium, phosphorus and protein intakes in post-MM compared to post-FF infants. Our findings demonstrate that dietary practices after hospital discharge likely have a greater impact on body composition in prematurely born infants than dietary practices in hospital. Whether the observed differences in body composition between breastfed and formula-fed preterm infants have any long-term consequences requires further investigation.

Body Composition↗