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Biomedical subjects

S P Walker

Publications and source records attributed to S P Walker.

At least 19 recordsLinked to original sources
PubMed2006

The association between early childhood stunting and weight status in late adolescence.

BACKGROUND: Cross-sectional studies have shown associations between stunting and overweight; however, there are few prospective studies of stunted children. OBJECTIVES: To determine whether stunting before age 2 years is associated with overweight and central adiposity at 17-18 years and whether growth in height among stunted children predicts body mass index (BMI) in late adolescence. DESIGN: Prospective cohort study. PARTICIPANTS: One-hundred and three participants stunted by age 2 years and 64 non-stunted participants (78% of participants enrolled in childhood). Participants were measured in early childhood and at ages 7, 11 and 17 years. RESULTS: Stunted subjects remained shorter and had lower BMIs, smaller skinfolds and circumferences than non-stunted subjects. Overweight (BMI >/=25 m(2)) was not significantly different among stunted and non-stunted male subjects (5.2 and 12.5%) but non-stunted female subjects were more likely to be overweight than those who experienced early childhood stunting (11.1 and 34.4%, P=0.013). Centralization of fat (waist to hip ratio (WHR), subscapular/triceps skinfold ratio (SSF/TSF)) did not differ between stunted and non-stunted groups (mean WHR 0.77 and mean SSF/TSF 1.18 in both groups). Stunted subjects with greater increases in height-for-age for the intervals 3-7 and 7-11 years had higher BMI at age 17 years (P=0.04 and P=0.001, respectively). CONCLUSION: Participants stunted by age 2 years were less likely to be overweight than those who were never stunted. This suggests that cross-sectional studies of the association between stunting and overweight may be misleading. Among stunted children, greater linear growth during mid- to late childhood was associated with greater BMI at age 17 years.

Adiposity↗
PubMed2004

Factors affecting umbilical venous perfusion during experimental cord knotting.

The aim was to determine experimentally the factors that increase the risk of venous occlusion by applying a standardised tightening force to isolated perfused umbilical cords tied in a true knot in vitro. Umbilical cords were collected from patients undergoing Caesarean section. Cords were clamped, isolated and studied within 15 min. The umbilical vein was cannulated, the cord tied in a true knot and traction was applied using standard weights. The umbilical vein was perfused with modified Krebs solution at a constant pressure of 40 mmHg and the attached weight increased until perfusion ceased. The cord mass index (weight/length), hydration index/100-[(dry weight/wet weight)x100], and coiling index (coils/length) were determined. Cord morphometric analysis was performed on 193 cords. Intra uterine growth restriction was associated with decreased cord mass index (p=0.002) and increased coiling index (p=0.002). Venous perfusion experiments were performed on 75 cords. Using multivariate regression analysis, cord morphometric factors that increased the risk of cord occlusion were decreased cord mass index (p=0.008), decreased cord hydration index (p=0.004), and low venous flow capacity (p=0.001). During experimental cord knotting with applied traction, the susceptibility to venous occlusion was increased with low cord mass index, low cord hydration index and low venous flow capacity. These cord characteristics were associated with low fetal body weight and intrauterine growth restriction. An increased susceptibility to cord occlusion may contribute to the higher perinatal morbidity and mortality in growth restricted pregnancies.

Female↗
PubMed2003

Obesity in a cohort of black Jamaican children as estimated by BMI and other indices of adiposity.

OBJECTIVE: To examine the relationships of body mass index (BMI) to obesity indices derived from anthropometry and to determine tracking of overweight between late childhood and early adolescence, in a cohort of children with mixed nutritional history. We also compared identification of overweight children using The International Obesity Task Force (IOTF) BMI cut-off points with skinfolds. DESIGN: Prospective study. SETTING: Kingston, Jamaica. SUBJECTS: A total of 306 children examined at 7-8 y and at 11-12 y. MEASUREMENTS: Triceps (TSF) and subscapular skinfolds (SSF), height and weight were measured. The sum of the skinfolds (sum SF), BMI, percentage body fat (%fat) and fat mass (FM) were calculated. Pubertal stage was assessed at 11-12 y. RESULTS: Overweight increased from 3.5 to 9.5% over the follow-up period. BMI was better correlated with the other indices of adiposity in girls and in the older age group. BMI tracking over follow up was high. In regression analysis BMI explained 52 and 61% of the variance in FM in boys and girls at 7-8 y. This increased to 69% in both sexes at 11-12 y. Using the IOTF cut-off points BMI had low sensitivity to identify children >85th percentile of the NHANES references for SSF. The sensitivity for those assessed by TSF and sum SF was higher, but between 14 and 30% of the children were misclassified. The specificity of BMI was high. CONCLUSIONS: Adiposity increased over follow-up. Although the cohort remained relatively lean BMI rank among the fattest children was maintained. Girls were fatter than boys, reflecting adult obesity patterns. Children identified as overweight by the IOTF BMI cut-off points are likely to have high body fatness. However the BMI cut-off points may not identify many children with high body fatness.

Adipose Tissue↗
PubMed2003

Factors associated with size and proportionality at birth in term Jamaican infants.

The objective of this study was to identify the factors associated with size and proportionality at birth in a cohort of term infants established to investigate their growth and development. One hundred and forty term low-birth-weight (birth-weight < 2,500 g) infants and 94 normal birth-weight infants (2,500- < 4,000 g) were recruited within 48 hours of birth at the main maternity hospital, Kingston, Jamaica. Birth anthropometry and gestational age were measured, and maternal information was obtained by interview and from hospital records. Controlling for gestational age, variables independently associated with birth-weight were rate of weight gain in the second half of pregnancy, maternal height, haemoglobin level < 9.5 microg/dL, time of first attendance in antenatal clinic, birth order, pre-eclampsia, and consumption of alcohol, with 33% of the variance in birth-weight explained. Birth length was associated only with maternal height and age, while measures of proportionality (ponderal index and head/length ratio) were associated with characteristics of the environment in late pregnancy, including rate of weight gain, weight in late pregnancy, and pre-eclampsia. The variation in maternal characteristics associated with size or proportionality at birth may reflect the times during gestation when different aspects of growth are most affected.

Adult↗
PubMed2002

Mid-trimester fetal subdural hemorrhage: prenatal diagnosis.

A routine antenatal ultrasound examination at 20 weeks' gestation revealed a space-occupying lesion in the fetal right cerebral hemisphere. The borders of the mass were indistinct and there was no midline shift. A small collection of echogenic bowel was identified at the right iliac fossa. In an attempt to explain both findings a provisional diagnosis of a fetal blood dyscrasia was made. Fetal cranial magnetic resonance imaging 24 h later confirmed the diagnosis of a subdural hemorrhage. Subsequent fetal blood sampling confirmed severe fetal thrombocytopenia. To our knowledge this is the first report of the antenatal diagnosis of spontaneous mid-trimester fetal subdural hemorrhage.

Adult↗
PubMed2002

Fasting levels of serum glucose, cholesterol and triglyceride at age eleven to twelve years in stunted and non-stunted Jamaican children.

AIM: To determine whether fasting serum concentrations of glucose, cholesterol and triglyceride at age 11-12 y (a) differed between children stunted in early childhood and those who were never stunted, (b) were related to birthweight or current anthropometry and (c) were related to stunting after controlling for current size. METHODS: Anthropometry, serum glucose and lipid concentrations were measured in 112 children stunted in early childhood and 181 non-stunted children. RESULTS: Children who were stunted in infancy remained shorter, weighed less and were significantly less fat than non-stunted children but had a more central distribution of fat. They were also less likely to have entered puberty. Non-stunted children had higher fasting serum triglyceride concentrations than stunted children (p < 0.05). There were no significant correlations between birthweight and fasting glucose or any measure of serum lipids. The percentage of variance in biochemical measures explained by anthropometry was low: between 2.1 for HDL cholesterol and 14.6 for triglyceride. Nutritional status in early childhood (stunted or non-stunted) made no additional contribution to the variance. CONCLUSIONS: Linear growth retardation in early childhood was not independently related to fasting serum concentrations of glucose, cholesterol and triglyceride at age 11-12 y. However, despite being thinner, stunted children had a more central distribution of fat.

Analysis of Variance↗
PubMed2002

Early childhood stunting and later behaviour and school achievement.

BACKGROUND: Stunting in early childhood is common in developing countries and is associated with poorer cognition and school achievement in later childhood. The effect of stunting on children's behaviours is not as well established and is examined here. METHOD: Children who were stunted at age 9 to 24 months and had taken part in a 2-year intervention programme of psychosocial stimulation with or without nutritional supplementation were reexamined at age 11-12 years and compared with non-stunted children from the same neighbourhoods. Their school and home behaviours were assessed using the Rutter Teacher and Parent Scales and school achievement was measured using the Wide Range Achievement Test (WRAT) and the Suffolk Reading Scales. RESULTS: No significant intervention effects were found among the stunted groups. Thus data from the four intervention groups were aggregated for subsequent analyses, comparing all 116 stunted children with 80 non-stunted children. Controlling for social background variables, the stunted group had more conduct difficulties (p < .05) as rated by their parents. They also had significantly lower scores in arithmetic, spelling, word reading and reading comprehension than the non-stunted children (all p < .001). Conduct difficulties and hyperactivity were related to poorer school achievement. Controlling for the children's IQ, the stunted children's arithmetic scores remained significantly lower than those of the non-stunted children, but reading and spelling scores were not different. CONCLUSIONS: Previously stunted children had more conduct difficulties at home, regardless of their social background, than non-stunted children. Their educational attainment was also poorer than non-stunted children and these results are suggestive of a specific arithmetic difficulty. Children with behaviour problems performed less well at school.

Achievement↗
PubMed2001

Blood pressure in late pregnancy and work outside the home.

OBJECTIVE: To assess maternal blood pressure (BP) responses to working outside the home in late pregnancy, using 24-hour ambulatory BP monitoring. METHODS: Our paired observational study involved 24-hour ambulatory BP monitoring of 100 normotensive women (51 primiparas, 49 multiparas) on work and nonwork days. Mean BP differences were calculated for working, postworking, sleeping, and 24-hour periods on both days. Main outcome measures were BP differences between work and nonwork days and subsequent pregnancy hypertension. Comparisons in BP between work and nonwork days were done with Student paired t test. Comparisons between study subgroups were done with unpaired t test. Potential predictors of change in BP were examined using multiple linear regression. RESULTS: During job time, BP was significantly higher on work days than on nonwork days. The mean increase in BP associated with work was 2.6 mmHg (systolic BP, P <.001), 2.8 mmHg (diastolic BP, P <.001), and 2.9 mmHg (mean arterial BP, P <.001). Those observations were independent of parity. More than 10% of our subjects had increased mean arterial BP of 10 mmHg or more during job time on work days compared with nonwork days. Higher absolute BP levels (regression coefficient 0.21, P =.04) and greater perceived job stress (regression coefficient 1.34, P =.04) correlated positively with BP increases at work. Twelve women developed hypertension. Those women had a larger increase on work days in mean systolic (6.6 mmHg compared with 2.1 mmHg, P =.013), mean diastolic (6.4 mmHg compared with 2.3 mmHg, P =.014), and mean arterial (7.4 mmHg compared with 2.3 mmHg, P =.002) BP compared with normotensive women. The magnitude of BP responses to work was a significant predictor of pregnancy hypertension, independent of absolute BP level. CONCLUSION: Blood pressure increased in women when they worked outside the home. The effect of maternal work is important when treating pregnancy hypertension. Ambulatory BP monitoring makes assessment of maternal BP responses to work a practical clinical option.

Adult↗
PubMed2001

The effect of vascular coiling on venous perfusion during experimental umbilical cord encirclement.

OBJECTIVE: The aim of these studies was to compare venous perfusion in umbilical cords subjected to a standardized tight encirclement force. Comparisons were made between cords from normal pregnancies and those complicated by gestational diabetes mellitus and intrauterine growth restriction. STUDY DESIGN: The cannulated cord segment was wrapped around a plastic container, which in turn was attached with nylon string to a hanging graduated measuring cylinder in which known volumes of water could be applied for weight. The cord was perfused with Krebs solution to a constant venous perfusion pressure of 40 mm Hg. Weights of 100-g increments were applied until total cessation of venous perfusion was observed. The weight, length, number of vascular coils, and degree of hydration were recorded for each cord. The coiling index was defined as the number of vascular coils per 10 cm of cord. RESULTS: Regression analysis of 34 cords (normal, n = 16; gestational diabetes mellitus, n = 12; intrauterine growth restriction, n = 6) identified a significant inverse correlation (P =.0003, Spearman rank correlation) between coiling index and the minimum weight required to occlude venous perfusion. Cords from pregnancies complicated by intrauterine growth restriction displayed a higher frequency of vascular coiling and were more easily occluded (median weight, 350 g) than were cords from pregnancies complicated by gestational diabetes mellitus, which were less coiled and tended to resist occlusion (median weight, 1100 g). CONCLUSION: During experimental cord encirclement there was a significant inverse relationship between vascular coiling and susceptibility to cord venous occlusion when traction was applied to the encirclement.

Biomechanical Phenomena↗
PubMed2001

Photothermal determination of optical coefficients of tissue phantoms using an optical fibre probe.

The absorption and reduced scattering coefficients of turbid tissue phantoms have been determined from photothermal measurements made using an optical fibre probe. The thermal sensor was a thin polymer film positioned at the end of a multimode optical fibre. The film was illuminated by the output of a continuous-wave diode laser and formed the cavity of a low-finesse Fabry-Perot interferometer. Low energy laser pulses, launched into the fibre and passed through the film, produced an abrupt temperature rise in the target tissue, which was placed in contact with the film. The subsequent conduction of heat into the film caused a change in its optical thickness and hence the reflected intensity. The absorption and reduced scattering coefficients of gelatine tissue phantoms of known optical properties were determined from the measurements using a numerical model of photothermal signal generation and maximum a posteriori estimation. The determined optical coefficients were in good agreement with the known values. The results showed that the probe can be used for the determination of optical coefficients provided the thermal coefficients of the target tissue are known with low uncertainty.

Gelatin↗
PubMed2001

The effects of birth weight and postnatal linear growth retardation on blood pressure at age 11-12 years.

STUDY OBJECTIVE: To determine the effects of birth weight and linear growth retardation (stunting) in early childhood on blood pressure at age 11-12 years. DESIGN: Prospective cohort study. SETTING: Kingston, Jamaica. PARTICIPANTS: 112 stunted children (height for age < -2 SD of the NCHS references) and 189 non-stunted children (height for age > -1 SD), identified at age 9-24 months by a survey of poor neighbourhoods in Kingston. MAIN RESULTS: Current weight was the strongest predictor of systolic blood pressure (beta= 4.90 mm Hg/SD weight 95%CI 3.97, 5.83). Birth weight predicted systolic blood pressure (beta = -1.28 mm Hg/SD change in birth weight, 95% CI -2.17, -0.38) after adjustment for current weight. There was a significant negative interaction between stunting in early childhood and current weight indicating a larger effect of increased current weight in children who experienced linear growth retardation in early childhood. There was no interaction between birth weight and current weight. The increase in blood pressure from age 7 to age 11-12 was greater in children with higher weight at age 11-12 and less in children with higher birth weight and weight at age 7. CONCLUSIONS: Birth weight predicted systolic blood pressure in Jamaican children aged 11-12. Postnatal growth retardation may potentiate the relation between current weight and blood pressure. Greater weight gain between ages 7 and 11 was associated with a greater increase in systolic blood pressure. The relation between growth and later blood pressure is complex and has prenatal and postnatal components.

Anthropometry↗
PubMed2001

Successful pregnancy outcome after preterm premature rupture of membranes at < 20 weeks. A report of three cases.

BACKGROUND: Spontaneous preterm premature rupture of the membranes occurring before 20 weeks' gestation carries a perinatal mortality of approximately 82% and potential for considerable morbidity for mother and fetus. This is in contrast to amniotic fluid leakage after second-trimester amniocentesis, when the prognosis is usually good. CASES: We report three cases of spontaneous rupture of the membranes before 20 weeks' gestation, all associated with reaccumulation of amniotic fluid and satisfactory neonatal outcomes. CONCLUSION: Our cases may represent a subgroup with a relatively good prognosis. The existence of such subgroups would better be determined in a prospective, cohort study, and it might need to be a multicenter one. It requires well-defined entry criteria, management protocols and neonatal follow-up as well as information about pregnancies where termination, rather than continuation, is chosen.

Adolescent↗
PubMed2000

Electroporation of salmon sperm for gene transfer: efficiency, reliability, and fate of transgene.

Uptake of exogenous DNA by electroporated salmon sperm for gene transfer is being investigated. Our studies show that electroporated salmon sperm cells were more efficient and more reliable than untreated sperm in picking up exogenous DNA and subsequently transferring the DNA into salmon embryos. Indirect evidence suggest that some of the exogenous DNA was internalized in the sperm nuclei. The taken up DNA retained its integrity as demonstrated by PCR. The foreign DNA was detected in 15-month-old fish, and had a mosaic pattern of distribution. Integration of the foreign DNA occurred infrequently, and the expression of the foreign genes was poor. The potential of sperm-mediated gene transfer as a routine protocol for mass gene transfer in salmon will be dependent on the improvement of integration and expression of the foreign gene.

Animals↗
PubMed2000

Nutritional deficiencies and later behavioural development.

The literature on the long-term effects of nutritional deficiencies in early life is reviewed. The severity and duration of the deficiency, the stage of the children's development, the biological condition of the children and the socio-cultural context may all modify the effect. There is substantial evidence that reduced breast-feeding, small-for-gestational-age birth weight, Fe and I deficiency, and protein-energy malnutrition (PEM) are associated with long-term deficits in cognition and school achievement. However, all these conditions are associated with poverty and poor health, which may account for the association. It is difficult to establish that the long-term relationship is causal, as it requires a randomized treatment trial with long-term follow-up. Such studies are only available for I deficiency in utero and early childhood PEM. Results from these studies indicate that I deficiency has a long-term effect and PEM probably has a long-term effect.

Behavior↗
PubMed2000

Early linear growth retardation and later blood pressure.

OBJECTIVE: To examine the effects of stunting in early childhood on blood pressure in later childhood. DESIGN: A cohort study. SETTING: Kingston, Jamaica. SUBJECTS: Seven to eight year old children, 120 stunted (height for age <-2 s.d. of the NCHS references) and 224 non-stunted (height for age >-1 s.d. of the NCHS references) at age 9-24 months. METHODS: Stunted and non-stunted children were identified at age 9-24 months by house to-house survey of poor neighbourhoods in Kingston, Jamaica. Blood pressure and anthropometry were measured at age 7-8 y. Birth weight was obtained from hospital records (73%) or maternal recall. RESULTS: The stunted children remained shorter and thinner than the non-stunted ones. In multiple regression analysis adjusting for size and pulse rate, the stunted children had higher systolic blood pressure (P<0.05). Birth weight was not a significant predictor of systolic blood pressure. CONCLUSION: Stunting in early childhood may increase the risk of elevated systolic blood pressure in later life. SPONSORSHIP: Nutricia Research Foundation, The Netherlands and the Commonwealth Caribbean Medical Research Council.

Anthropometry↗
PubMed2000

Effects of growth restriction in early childhood on growth, IQ, and cognition at age 11 to 12 years and the benefits of nutritional supplementation and psychosocial stimulation.

OBJECTIVES: (1) To determine whether benefits to growth and cognition remain after intervention in growth-restricted children who received psychosocial stimulation and nutritional supplementation in early childhood. (2) To investigate the extent of the differences in IQ and cognition at age 11 to 12 years between growth-restricted and non-growth-restricted children. STUDY DESIGN: Growth-restricted and non-growth-restricted children were identified at age 9 to 24 months, at which time the growth-restricted children participated in a 2-year randomized trial of nutritional supplementation and psychosocial stimulation. Eight years after the interventions ended, the children's growth, IQ, and cognitive functions were measured. RESULTS: There were no significant benefits from supplementation to growth or cognition. Children who had received stimulation had higher scores on the Weschler Intelligence Scales for Children-Revised full-scale (IQ) and verbal scale and tests of vocabulary and reasoning (all P <.05). The growth-restricted children had significantly lower scores than the non-growth-restricted children on 10 of 11 cognitive tests. CONCLUSIONS: Psychosocial stimulation had small but significant long-term benefits on cognition in growth-restricted children. Growth-restricted children had significantly poorer performance than non-growth-restricted children on a wide range of cognitive tests, supporting the conclusion that growth restriction has long-term functional consequences.

Child↗