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Biomedical subjects

C T Cowell

Publications and source records attributed to C T Cowell.

At least 19 recordsLinked to original sources
PubMed2006

Soft drink consumption and excess weight gain in Australian school students: results from the Nepean study.

We studied the relation between soft drink/cordial (a sweet, flavoured, concentrated syrup that is mixed with water to taste), fruit juice/drink and milk consumption in mid-childhood, and body mass index (BMI) status in early adolescence in a contemporary Australian cohort. In 1996/7, 268 children (136 males) were recruited from western Sydney at baseline (mean+/-s.d.: 7.7+/-0.6 years), and at follow-up 5 years later (13.0+/-0.2 years). Height and weight were measured at both time periods and overweight and obesity defined using the International Obesity TaskForce criteria. Beverage consumption was calculated from a 3-day food record at baseline. Median carbohydrate intake from soft drink/cordial was 10 g higher (P=0.002) per day in children who were overweight/obese at follow-up compared to those who had an acceptable BMI at both baseline and follow-up. Intakes of soft drink/cordial in mid-childhood, but not fruit juice/fruit drink and milk, were associated with excess weight gain in early adolescence.

Animals↗
PubMed2005

The re-emerging burden of rickets: a decade of experience from Sydney.

AIM: To define the demographics and clinical characteristics of cases presenting with nutritional rickets to paediatric centres in Sydney, Australia. METHODS: Retrospective descriptive study of 126 cases seen from 1993 to 2003 with a diagnosis of vitamin D deficiency and/or confirmed rickets defined by long bone x ray changes. RESULTS: A steady increase was seen in the number of cases per year, with a doubling of cases from 2002 to 2003. Median age of presentation was 15.1 months, with 25% presenting at less than 6 months of age. The most common presenting features were hypocalcaemic seizures (33%) and bowed legs (22%). Males presented at a younger age, with a lower weight SDS, and more often with seizures. The caseload was almost exclusively from recently immigrated children or first generation offspring of immigrant parents, with the region of origin predominantly the Indian subcontinent (37%), Africa (33%), and the Middle East (11%). Seventy nine per cent of the cases were born in Australia. Eleven cases (all aged <7 months) presented atypically with hyperphosphataemia. CONCLUSIONS: This large case series shows that a significant and increasing caseload of vitamin D deficiency remains, even in a developed country with high sunlight hours. Cases mirror recent immigration trends. Since birth or residence in Australia does not appear to be protective, screening of at risk immigrant families should be implemented through public health policies.

Child, Preschool↗
PubMed2005

Increasing central adiposity: the Nepean longitudinal study of young people aged 7-8 to 12-13 y.

BACKGROUND: Estimates of the prevalence of overweight and obesity in young people are typically based on body mass index (BMI). However, BMI may not indicate the level of central adiposity. Waist circumference has therefore been recommended to identify young people at risk of morbidity associated with central adiposity. OBJECTIVE: To investigate (a) change in total and central adiposity between 7-8 and 12-13 y (b) agreement between classifying young people as overweight or obese based on total adiposity and central adiposity, and (c) risk factors associated with the development of total and central adiposity. DESIGN: Anthropometric measurements were taken on 342 children in 1996/97 and 5 y later. Risk factors examined included birth weight, physical activity, TV viewing, pubertal status, parental adiposity, diet and socio-economic status. RESULTS: Between 7-8 and 12-13 y indices of central adiposity increased more than total adiposity; waist circumference z-score increased by (mean+/-s.d.) 0.74+/-0.92 and BMI z-score increased by 0.18+/-0.67. At 12-13 y there was moderate agreement between the two measures of adiposity (weighted kappa=0.64). However, waist circumference identified a greater number of young people as overweight or obese compared to BMI (41.2 vs 29.3%, P<0.001). Adiposity status at 7-8 y, maternal obesity, and pubertal stage were the strongest predictors of BMI status at 12-13 y. Risk factors associated with increased central adiposity were similar. CONCLUSIONS: Overweight and obesity, as measured by waist circumference, is a bigger problem than is currently assessed by BMI. Targeting known risk factors for total adiposity may be an appropriate strategy for preventing increased central adiposity.

Adiposity↗
PubMed2005

Cyclic bisphosphonate therapy in osteogenesis imperfecta type V.

The clinical and radiographic features and management of a young person with recently delineated Osteogenesis Imperfecta Type V is described. A female aged 9 years presented with a history of multiple fractures since 3 years of age and bilateral dislocation of the elbows from infancy. She was commenced on a low dose frequent regimen of cyclic intravenous pamidronate, which resulted in progressive improvement in bone density, reduced fracture frequency and remission of symptoms of osteoporosis.

Anti-Inflammatory Agents↗
PubMed2004

Features of the metabolic syndrome after childhood craniopharyngioma.

Obesity and multiple pituitary hormone deficiency are common complications after surgery for childhood craniopharyngioma. We hypothesized that post craniopharyngioma surgery, children are at high risk for the metabolic syndrome, including insulin resistance due to excess weight gain and GH deficiency. This study characterized body composition (anthropometry and dual energy x-ray absorptiometry) and metabolic outcomes in 15 children (10 males and 5 females; age, 12.2 yr; range, 7.2-18.5 yr) after surgical removal of craniopharyngioma. In 9 subjects, outcomes were compared with those of healthy age-, sex-, body mass index-, and pubertal stage-matched controls. Insulin sensitivity was measured by 40-min iv glucose tolerance test. Seventy-three percent of subjects were overweight or obese. Sixty-six percent had normal growth velocity without GH treatment. Subjects had increased abdominal adiposity (P = 0.008) compared with controls. However, there was no significant difference in total body fat. Subjects had higher fasting triglycerides (P = 0.02) and lower high density lipoprotein cholesterol to total cholesterol ratio (P = 0.015). Insulin sensitivity was equally reduced for subjects and controls (P = 0.86). After craniopharyngioma removal, patients had more features of the metabolic syndrome compared with controls. This could be a result of hypothalamic damage causing obesity and GH deficiency. Further studies exploring predictors of the metabolic syndrome after craniopharyngioma surgery are required.

Abdomen↗
PubMed2003

Importance of lean mass in the interpretation of total body densitometry in children and adolescents.

OBJECTIVE: Most studies that use total body dual energy x-ray absorptiometry (DEXA) in children rely on areal bone mineral density (BMD=bone mineral content [BMC]/bone area [BA]) and compare the output with age- and sex-specific normative data. Because this approach is prone to size-related misinterpretation, this study focuses on the interrelations among BMC, body size (height), and lean tissue mass (LTM). STUDY DESIGN: This cross-sectional study presents normative total body LTM data in relation to height and BMC for 459 healthy white subjects (249 female), 3 to 30 years of age. Guidelines for DEXA interpretation in children are provided and illustrated for patients with growth hormone deficiency (n=5) and anorexia nervosa (n=5). RESULTS: LTM/height tended to be greater in male than in girls. The BMC/LTM ratio was greater in female than in boys (P<.001), even after adjustment for age and height. Sex-specific reference curves were created for LTM/height, the BMC/LTM ratio, BA/height, and BMC/BA. CONCLUSIONS: We recommend that total body DEXA in children should be interpreted in 4 steps: (1) BMD or BMC/age, (2) height/age, (3) LTM/height, and (4) BMC/LTM ratio for height. This allows differentiation of the origin of a low BMD or BMC/age, for example, short stature and primary, secondary, and mixed bone defects.

Absorptiometry, Photon↗
PubMed2003

A comparison of bone geometry and cortical density at the mid-femur between prepuberty and young adulthood using magnetic resonance imaging.

In upper extremity bones, a sexual dimorphism exists in the development of periosteal and endocortical bone surfaces during growth. Little is known about developmental patterns of bone geometry at weight-bearing bones like the femur. Using MRI and dual energy X-ray absorptiometry (DXA), this study assessed the differences in mid-femoral total (TA), cortical (CA) and medullary areas (MA), cortical thickness, and cortical density (BMD(compartment)) between prepuberty and young adulthood in 145 healthy subjects (94 females) 6 to 25 years old. Additionally, agreement between mid-femoral total bone volume (TV) measurements by DXA and MRI were investigated. In both sexes, TA, CA, MA, and cortical thickness were significantly larger in adults compared to prepubertal subjects (P < 0.001), and males had greater values than females. This sex difference persisted for TA, CA, and cortical thickness (P < 0.05), but not MA, after adjusting for femur length and weight. Mean (SD) cortical BMD increased from 1.05 (0.07) and 1.09 (0.10) g/cm(3) in prepubertal children to 1.46 (0.14) and 1.42 (0.1) g/cm(3) in young adults, females and males, respectively (P < 0.001). TV measurements by DXA were significantly greater than by MRI (P < 0.001) in young adults. In conclusion, periosteal and endocortical expansion and increasing cortical BMD are the growth processes found at the mid-femur in both sexes. Our findings contrast to that in upper extremity bones, where MA is constant in females during growth. The difference in femoral bone development may be due to higher strains caused by weight bearing and genetic factors. DXA, in contrast to MRI, is inaccurate in the determination of mid-femoral TV measures.

Adolescent↗
PubMed2003

Use of bisphosphonate therapy for osteoporosis in childhood and adolescence.

Congenital and acquired forms of osteoporosis in childhood and adolescence can result in morbidity from fracture and pain in childhood, and place an individual at significant risk for problems in adult life. A range of therapies exist for the prevention and treatment of osteoporosis, including optimization of daily calcium intake, adequate vitamin D status, weight-bearing exercise, treatment with sex steroids where delayed puberty is a problem and, more recently, use of bisphosphonate therapy. Intravenous pamidronate therapy (a bisphosphonate) has been shown to reduce fractures and improve bone density in children with osteogenesis imperfecta, and might prove to be of benefit in other osteoporotic conditions in childhood. However, a number of issues regarding the optimal use of bisphosphonate therapy in children and adolescents remain to be resolved, including total annual dose and frequency and duration of administration. Bisphosphonate therapy should, therefore, be used only in the context of a well-run clinical programme with specialist knowledge in the management of osteopenic disorders in childhood.

Absorptiometry, Photon↗
PubMed2003

Slowing of growth in height and weight on stimulants: a characteristic pattern.

OBJECTIVE: The aims of the present study were to describe the growth pattern of children starting stimulant medication and to analyse the changes over time in height, weight and height velocity in a cohort of treated patients. METHODS: Retrospective review of growth data from files of all newly treated patients with attention-deficit/hyperactivity disorder in one paediatric practice. Forty-four boys and seven girls were treated for 6-42 months with either dexam-phetamine (n = 32) or methylphenidate (n = 19). RESULTS: During the first 6 months on stimulant medication 44 children (86%) had a height velocity below the age-corrected mean and there was weight loss in 39 (76%). The height and weight standard deviation score (SDS) showed a progressive decline that was statistically significant after 6 and 18 months (P < 0.001, paired t-test). The height velocity was significantly attenuated for the first 30 months (P < 0.01), being lowest during the first 6 months. The mean height deficit during the first 2 years was approximately 1 cm/year. The change in weight SDS was 2.4 times the change in height SDS after 30 months on treatment with a significant correlation (Pearson's correlation coefficient r = 0.88, P < 0.001). CONCLUSIONS: Stimulant medication is associated with a decrease in height and weight SDS during the first 6-30 months with a characteristic pattern on the growth chart.

Adolescent↗
PubMed2001

Effect of pamidronate on distraction osteogenesis and fixator-related osteoporosis.

We examined the effect on bone mineral density (BMD), bone mineral content (BMC) and mechanical properties of a single 1.0 mg/kg dose of the bisphosphonate pamidronate (Novartis), in a distraction osteogenesis model in immature rabbits. Twenty rabbits underwent a tibial osteotomy. Ten rabbits received pamidronate 1.0 mg/kg via ear vein intra-operatively while 10 received saline infusions only. After a 24 h latency, all underwent distraction of 0.375 mm twice daily for 15 days. The animals were culled at 42 days. After culling, the distracted and non-distracted tibiae were examined by quantitative computer tomography (QCT). The volumetric bone mineral density (vBMD, mg/cm(3)) in the bone proximal and distal to the regenerate in the operated limb was increased by a mean of 11 and 14%, respectively, compared to controls (P<0.05). The vBMD of the regenerate bone was increased by a mean of 8% over controls (NS, P=0.17). The bone mineral content (BMC, mg) was increased by 23% (proximal and distal) (P<0.05) in the bone surrounding the lengthening and there was a 17% trend towards an increase in the regenerate (NS, P=0.3). Four-point bending analysis documented that the load to failure was increased by 32% from 436 to 574 N (P<0.01) in the pamidronate group. The modulus of elasticity was not different between the control and pamidronate groups (P=0.3), and in both groups was only approximately one-third of the intact tibiae (P<0.001). The administration of a single dose of pamidronate can improve the bone mineral density, content and mechanical properties of a bone undergoing distraction osteogenesis.

Animals↗
PubMed2001

Abdominal fat and birth size in healthy prepubertal children.

BACKGROUND: Studies examining the foetal origins hypothesis suggest that small birth size may be a marker of foetal adaptations that programme future propensity to adult disease. We explore the hypothesis that birth size may relate to fat distribution in childhood and that fat distribution may be a link between birth size and adult disease. OBJECTIVE: To investigate the relationship between birth size and abdominal fat, blood pressure, lipids, insulin and insulin:glucose ratio in prepubertal children. DESIGN: Cross-sectional study, based on a birth cohort of consecutive full-term births. SUBJECTS: Two hundred and fifty-five (137 females) healthy, 7- and 8-y-old children. MEASUREMENTS: Body composition and abdominal fat was measured by dual energy X-ray absorptiometry. Lipid, glucose and insulin profiles were measured after an overnight fast and an automated BP monitor was used for blood pressure measurements. RESULTS: There was a negative association between abdominal fat and birth weight s.d. score across a range of normal birth weights (beta=-0.18; 95% CI=-0.31 to -0.04, P=0.009) and a positive association with weight s.d. score at 7/8 y (beta=0.35; 95% CI=0.24 to 0.46, P<0.001). Children who were born with the lowest weight s.d. score and had the greatest weight s.d. score at 7/8 y had significantly more (P<0.001) abdominal fat, as a percentage of total fat (6.53+/-1.3%) than those who had the highest birth weight s.d. score and the lowest weight s.d. score at 7/8 y (4.14+/-0.5%). Similar results were seen if head circumference, but not ponderal index, was used as an indicator of birth size. Increased abdominal fat was associated with higher total cholesterol:HDL cholesterol, higher triglyceride concentration and increased diastolic blood pressure. CONCLUSIONS: Birth weight independently predicted abdominal fat. Children with the highest amount of abdominal fat were those who tended to be born lighter and gained weight centiles. Increased abdominal fat was associated with precursor risk factors for ischaemic heart disease.

Abdomen↗
PubMed2001

Ten years' experience of persistent hyperinsulinaemic hypoglycaemia of infancy.

OBJECTIVE: To review the presentation, management and outcome of persistent hyperinsulinaemic hypoglycaemia of infancy seen at the Royal Alexandra Hospital for Children over a 10 year period. METHODOLOGY: A retrospective review of 20 subjects was performed. As well as laboratory data, data were collected on clinical presentation, medical and surgical management and developmental outcome. RESULTS: Twenty subjects (11 male) were identified with presentation at a median age of 1.5 months (range 0-10 months), with 10 (50%) presenting in the first week of life. Only 20% of patients were large for gestational age. Diagnosis was made on the basis of high glucose requirements and inappropriately high insulin levels at the time of hypoglycaemia. Eight (40%) responded well to diazoxide treatment alone, seven (35%) received diazoxide in combination with other short-term medical therapy initially and five (25%) required pancreatectomy (repeat surgery in three). Those who required surgery had a higher mean birth weight. Infants presenting in the first week of life were less likely to respond to diazoxide. At the time of last review, eight (40%) of those treated medically had ceased all treatment. Two of the five cases requiring pancreatectomy now require insulin treatment. Neurodevelopmental assessment was normal in 11 (55%), mild delay was found in six (30%) and moderate or severe delay was found in three (15%). CONCLUSIONS: Persistent hyperinsulinaemic hypoglycaemia of infancy remains a major diagnostic and management challenge. Early suspicion and recognition is critical with definitive investigation and medical therapy to avoid hypoglycaemia, with pancreatectomy in medically unresponsive cases. Normal neurodevelopmental outcome was found in only 55% of cases.

Adolescent↗
PubMed2001

Growth hormone treatment in children with chronic renal failure: a meta-analysis of randomized controlled trials.

OBJECTIVE: To evaluate the benefits and side effects of recombinant human growth hormone (hGH) treatment in children with chronic renal failure. METHODS: Two reviewers independently assessed relevant randomized controlled trials for methodologic quality, extracted data, and estimated summary treatment effects by use of a random effects model. RESULTS: Ten randomized controlled trials involving 481 children were identified. Treatment with hGH (28 IU/m(2)/wk) resulted in a significant increase in height standard deviation score at 1 year (4 trials, weighted mean difference [WMD] = 0.77, 95% CI = 0.51 to 1.04), and a significant increase in height velocity at 6 months (2 trials, WMD = 5.7 cm/y, 95% CI 4.4 to 7.0) and 1 year (2 trials, WMD = 4.1 cm/y, 95% CI 2.6 to 5.6), but there was no further increase in height indexes during the second year of administration. Compared with the 14 IU/m(2)/wk group, there was an increase of 1.4 cm/y (0.6 to 2.2) in height velocity in the group treated with 28 IU/m(2)/wk. The frequency of reported side effects of hGH were similar to that of the control group. CONCLUSION: On average, 1 year of treatment with 28 IU/m(2)/wk hGH in children with chronic renal failure results in an increase of 4 cm/y in height velocity above that of untreated control subjects, but there was no demonstrable benefit for longer courses or higher doses of treatment.

Adolescent↗
PubMed2001

Mutational analysis and genotype-phenotype correlation of the PHEX gene in X-linked hypophosphatemic rickets.

PHEX is the gene defective in X-linked hypophosphatemic rickets. In this study, analysis of PHEX revealed mutations in 22 hypophosphatemic rickets patients, including 16 of 28 patients in whom all 22 PHEX exons were studied. In 13 patients, in whom no PHEX mutation had been previously detected in 17 exons, the remaining 5 PHEX exons were analyzed and mutations found in 6 patients. Twenty different mutations were identified, including 16 mutations predicted to truncate PHEX and 4 missense mutations. Phenotype analysis was performed on 31 hypophosphatemic rickets patients with PHEX mutations, including the 22 patients identified in this study, 9 patients previously identified, and affected family members. No correlation was found between the severity of disease and the type or location of the mutation. However, among patients with a family history of hypophosphatemic rickets, there was a trend toward more severe skeletal disease in patients with truncating mutations. Family members in more recent generations had a milder phenotype. Postpubertal males had a more severe dental phenotype. In conclusion, although identifying mutations in PHEX may have limited prognostic value, genetic testing may be useful for the early identification and treatment of affected individuals. Furthermore, this study suggests that other genes and environmental factors affect the severity of hypophosphatemic rickets.

Adolescent↗
PubMed2001

Intravenous pamidronate reduces osteoporosis and improves formation of the regenerate during distraction osteogenesis. A study in immature rabbits.

We examined the effect on bone mineral density (BMD) of a single dose of 3 mg/kg of the bisphosphonate, pamidronate (Novartis) in distraction osteogenesis in immature rabbits. Seventeen rabbits (9 control, 8 given pamidronate) were examined by dual-energy x-ray absorptiometry. There was a significant increase in the BMD in the pamidronate group compared with the control animals. The mean areal BMD (g/cm2) in the bone proximal and distal to the regenerate was increased by 40% and 39%, respectively, compared with the control group (p < 0.05). The BMD of the regenerate bone was increased by a mean of 43% (p < 0.05). There was an increase of 22% in the mean area of regenerate formed in the pamidronate group (p < 0.05). Histological examination of bone in nine rabbits (5 control, 4 pamidronate) showed an increase in osteoblastic rimming and mineralisation of the regenerate, increased formation of bone around the pin sites and an increase in the cortical width of the bone adjacent to the regenerate in the rabbits given pamidronate. Pamidronate had a markedly positive effect. It reduced the disuse osteoporosis normally associated with lengthening using an external fixator and increased the amount and density of the regenerate bone. Further study is required to examine the mechanical properties of the regenerate after the administration of pamidronate.

Animals↗
PubMed2001

Measurement of midfemoral shaft geometry: repeatability and accuracy using magnetic resonance imaging and dual-energy X-ray absorptiometry.

Although macroscopic geometric architecture is an important determinant of bone strength, there is limited published information relating to the validation of the techniques used in its measurement. This study describes new techniques for assessing geometry at the midfemur using magnetic resonance imaging (MRI) and dual-energy X-ray absorptiometry (DXA) and examines both the repeatability and the accuracy of these and previously described DXA methods. Contiguous transverse MRI (Philips 1.5T) scans of the middle one-third femur were made in 13 subjects, 3 subjects with osteoporosis. Midpoint values for total width (TW), cortical width (CW), total cross-sectional area (TCSA), cortical cross-sectional area (CCSA), and volumes from reconstructed three-dimensional (3D) images (total volume [TV] and cortical volume [CVol]) were derived. Midpoint TW and CW also were determined using DXA (Lunar V3.6, lumbar software) by visual and automated edge detection analysis. Repeatability was assessed on scans made on two occasions and then analyzed twice by two independent observers (blinded), with intra- and interobserver repeatability expressed as the CV (CV +/- SD). Accuracy was examined by comparing MRI and DXA measurements of venison bone (and Perspex phantom for MRI), against "gold standard" measures made by vernier caliper (width), photographic image digitization (area) and water displacement (volume). Agreement between methods was analyzed using mean differences (MD +/- SD%). MRI CVs ranged from 0.5 +/- 0.5% (TV) to 3.1 +/- 3.1% (CW) for intraobserver and 0.55 +/- 0.5% (TV) to 3.6 +/- 3.6% (CW) for interobserver repeatability. DXA results ranged from 1.6 +/- 1.5% (TW) to 4.4 +/- 4.5% (CW) for intraobserver and 3.8 +/- 3.8% (TW) to 8.3 +/- 8.1% (CW) for interobserver variation. MRI accuracy was excellent for TV (3.3 +/- 6.4%), CVol (3.5 +/- 4.0%), TCSA (1.8 +/- 2.6%), and CCSA (1.6 +/- 4.2%) but not TW (4.1 +/- 1.4%) or CW (16.4 +/14.9%). DXA results were TW (6.8 +/- 2.7%) and CW (16.4 +/- 17.0%). MRI measures of geometric parameters of the midfemur are highly accurate and repeatable, even in osteoporosis. Both MRI and DXA techniques have limited value in determining cortical width. MRI may prove valuable in the assessment of surface-specific bone accrual and resorption responses to disease, therapy, and variations in mechanical loading.

Absorptiometry, Photon↗
PubMed2000

Growth and endocrine function in children with acute myeloid leukaemia after bone marrow transplantation using busulfan/cyclophosphamide.

Longitudinal studies of growth and endocrine function of children with AML transplanted with BUCY are limited. We report a cohort of 23 children with AML transplanted (15 autologous and eight allogeneic) following a single chemotherapy protocol and surviving at least 2 years after BMT. Busulfan was given as a single daily dose. Growth and endocrine function was evaluated yearly from one up to 10 years post transplant (median 4.9 years). The mean height standard deviation score (HtSDS) of the entire group decreased from 0.01 (s.e.m. +/- 0.25) at diagnosis to -0.38 (+/- 0.28) at BMT (P = 0.001). There was no statistically significant difference between HtSDS at BMT and yearly HtSDS from 1 to 5 years post BMT. There was no significant relationship between age at BMT and subsequent change in HtSDS. To date, five of six girls have needed sex steroid replacement. Six of 12 evaluable boys had abnormal gonadotrophins, but none required sex steroid replacement. Children with AML who undergo BMT with BUCY show no significant growth impairment, but gonadal dysfunction is prominent, particularly in girls. Bone Marrow Transplantation (2000).

Acute Disease↗