Biomedical subjects

Roy J Powell

Publications and source records attributed to Roy J Powell.

4 recordsLinked to original sources

PubMed2006

Assessing newborn body composition using principal components analysis: differences in the determinants of fat and skeletal size.

BACKGROUND: Birth weight is a composite of skeletal size and soft tissue. These components are likely to have different growth patterns. The aim of this paper is to investigate the association between established determinants of birth weight and these separate components. METHODS: Weight, length, crown-rump, knee-heel, head circumference, arm circumference, and skinfold thicknesses were measured at birth in 699 healthy, term, UK babies recruited as part of the Exeter Family Study of Childhood Health. Corresponding measurements were taken on both parents. Principal components analysis with varimax rotation was used to reduce these measurements to two independent components each for mother, father and baby: one highly correlated with measures of fat, the other with skeletal size. RESULTS: Gestational age was significantly related to skeletal size, in both boys and girls (r = 0.41 and 0.52), but not fat. Skeletal size at birth was also associated with parental skeletal size (maternal: r = 0.24 (boys), r = 0.39 (girls) ; paternal: r = 0.16 (boys), r = 0.25 (girls)), and maternal smoking (0.4 SD reduction in boys, 0.6 SD reduction in girls). Fat was associated with parity (first borns smaller by 0.45 SD in boys; 0.31 SD in girls), maternal glucose (r = 0.18 (boys); r = 0.27 (girls)) and maternal fat (r = 0.16 (boys); r = 0.36 (girls)). CONCLUSION: Principal components analysis with varimax rotation provides a useful method for reducing birth weight to two more meaningful components: skeletal size and fat. These components have different associations with known determinants of birth weight, suggesting fat and skeletal size may have different regulatory mechanisms, which would be important to consider when studying the associations of birth weight with later adult disease.

Adiposity↗

PubMed2005

Evidence of genetic regulation of fetal longitudinal growth.

BACKGROUND: Genetic as well as environmental factors are important determinants of fetal growth but there have been few studies of the influence of paternal factors on fetal growth. AIM: To study the influence of paternal anthropometry on detailed measurements of offspring at birth. DESIGN: A prospective cohort study involving biochemistry, and anthropometry, of mothers and fathers at 28 weeks gestation, and detailed anthropometry of children within 24 h of birth. SUBJECTS: 567 White Caucasian singleton, non-diabetic, full term pregnancies recruited from central Exeter, UK. RESULTS: Paternal height, but not paternal BMI, was correlated with birth weight (r = 0.19) and with birth length (r = 0.33). This was independent of potential confounders and maternal height. All measurements of fetal skeletal growth including crown-rump, knee-heel and head circumference were associated with paternal height. Maternal height showed similar correlations with birth weight (r = 0.18) and birth length (r = 0.26). Maternal BMI was correlated with birth weight (r = 0.27) and birth length (r = 0.15). In a multifactorial analysis 38% of the variance in fetal height could be explained by gestation, sex, paternal height, maternal height, maternal glucose, maternal BMI, parity and maternal smoking. CONCLUSION: Paternal height has an independent influence on size at birth. This predominantly influences length and skeletal growth of the baby. In contrast to maternal obesity the degree of paternal obesity does not influence birth weight. This work suggests that there is genetic regulation of skeletal growth while the maternal environment predominantly alters the adiposity of the fetus.

Adolescent↗

PubMed2003

Genetic cause of hyperglycaemia and response to treatment in diabetes.

BACKGROUND: Type 2 diabetes shows evidence of underlying heterogeneity. No studies have assessed whether different causes for diabetes change the response to oral hypoglycaemic therapy. In a few cases, patients with diabetes caused by mutations in the hepatocyte nuclear factor 1alpha (HNF-1alpha) gene have been described as sensitive to the hypoglycaemic effects of sulphonylureas. We aimed to see whether the glycaemic response to the sulphonylurea gliclazide and the biguanide metformin differed in HNF-1alpha diabetes and type 2 diabetes, and to investigate the mechanism for differences in sulphonylurea sensitivity. METHODS: We did a randomised crossover trial of glicazide and metformin in 36 patients, either with diabetes caused by HNF-1alpha mutations or type 2 diabetes, who were matched for body-mass index and fasting plasma glucose. The primary outcome was reduction in fasting plasma glucose. Analysis was by intention to treat. We assessed possible mechanisms for sulphonylurea sensitivity through insulin sensitivity, insulin secretory response to glucose and tolbutamide, and tolbutamide clearance. FINDINGS: Patients with HNF-1alpha diabetes had a 5.2-fold greater response to gliclazide than to metformin (fasting plasma glucose reduction 4.7 vs 0.9 mmol/L, p=0.0007) and 3.9-fold greater response to gliclazide than those with type 2 diabetes (p=0.002). Patients with HNF-1alpha diabetes had a strong insulin secretory response to intravenous tolbutamide despite a small response to intravenous glucose, and were more insulin sensitive than those with type 2 diabetes. Sulphonylurea metabolism was similar in both patient groups. INTERPRETATION: The cause of hyperglycaemia changes the response to hypoglycaemic drugs; HNF-1alpha diabetes has marked sulphonylurea sensitivity. This pharmacogenetic effect is consistent with models of HNF-1alpha deficiency, which show that the beta-cell defect is upstream of the sulphonylurea receptor. Definition of the genetic basis of hyperglycaemia has implications for patient management.

ATP-Binding Cassette Transporters↗

PubMed2002

The differential blood pressure sign in general practice: prevalence and prognostic value.

BACKGROUND: Patients sometimes have differences of > or =20/10 mmHg in their blood pressure depending on which arm is measured. The prevalence and prognostic value of this finding in general practice are unknown. If these differences are due to peripheral vascular disease, these patients may be at increased risk of cardiovascular or cerebrovascular events. OBJECTIVE: Our aim was to establish the frequency and prognostic value of a blood pressure difference between arms in one rural general practice. METHODS: Paired blood pressure readings were collected from patients attending the surgery. The outcome measures of myocardial infarction, new diagnosis of angina, a cerebrovascular event or death were recorded prospectively. RESULTS: A total of 280 patients were examined, and of these 13.6% had a systolic blood pressure difference (SBPD) of > or =20 mmHg, and 23.2% a diastolic blood pressure difference (DBPD) of > or =10 mmHg. Eighty-three patients were followed-up for 5.6 years. Patients with a DBPD of > or =10 mmHg showed a mean event-free survival of 3.3 years [95% confidence interval (CI) 2.2-4.4] compared with 5.0 years (95% CI 4.7-5.3) for those with a DBPD of <10 mmHg (P < 0.0001). Patients with an SBPD of > or =20 mmHg showed a mean event-free survival of 3.5 years (95% CI 2.3-4.7) compared with 4.9 years (95% CI 4.5-5.2) for an SBPD of <20 mmHg (P = 0.043). CONCLUSIONS: During a single assessment of blood pressure, there will be a minority of patients with a difference of > or =20/10 mmHg between their right and left arms. Measurement of both arms is therefore necessary to diagnose and treat hypertension accurately. This study suggests an association between blood pressure difference and increased morbidity and mortality. Priority should be given to managing other risk factors aggressively in those patients with a reproducible blood pressure difference of > or =20/10 mmHg.

Adult↗