Biomedical subjects

C A Powell

Publications and source records attributed to C A Powell.

At least 37 records · Page 2Linked to original sources

PubMed1997

Effects of early childhood supplementation with and without stimulation on later development in stunted Jamaican children.

It is not known whether nutritional supplementation in early childhood has long-term benefits on stunted children's mental development. We followed up 127 7-8-y old children who had been stunted in early childhood and received supplementation, stimulation, or both. At 9-24 mo of age, the children had been randomly assigned to four treatment groups: nutritional supplementation, stimulation, both treatments, and control. After 2 y, supplementation and stimulation had independent benefits on the children's development and the effects were additive. The group receiving both treatments caught up to a matched group of 32 nonstunted children. Four years after the end of the 2-y intervention 97% of the children were given a battery of cognitive function, school achievement, and fine motor tests. An additional 52 nonstunted children were included. Factor analyses of the test scores produced three factors: general cognitive, perceptual-motor, and memory. One, the perceptual-motor factor, showed a significant benefit from stimulation, and supplementation benefited only those children whose mothers had higher verbal intelligence quotients. However, each intervention group had higher scores than the control subjects on more tests than would be expected by chance (supplemented and both groups on 14 of 15 tests, P = 0.002; stimulated group in 13 of 15 tests, P = 0.01), suggesting a very small global benefit. There was no longer an additive effect of combined treatments at the end of the intervention. The stunted control group had significantly lower scores than the nonstunted children on most tests. Stunted children's heights and head circumferences on enrollment significantly predicted intelligence quotient at follow-up.

Anthropometry↗

PubMed1997

Phenotypic variation in transgenic tobacco expressing mutated geminivirus movement/pathogenicity (BC1) proteins.

Tobacco plants were transformed with the movement protein (pathogenicity) gene (BC1) from tomato mottle geminivirus (TMoV), using Agrobacterium-mediated transformation. Different transgenic tobacco lines that expressed high levels of the BC1 protein had phenotypes ranging from plants with severe stunting and leaf mottling (resembling geminivirus symptoms) to plants with no visible symptoms. The sequence data for the BC1 transgene from the transgenic plants with the different phenotypes indicated an association of spontaneously mutated forms of the BC1 gene in the transformed tobacco with phenotype variations. One mutated transgene associated with an asymptomatic phenotype had a major deletion at the C terminus of 119 amino acid residues with a recombination resulting in the addition of 26 amino acid residues of unidentified origin. This asymptomatic, mutated BC1 attenuated the phenotypic expression of the symptomatic BC1 in a tobacco line containing both copies of the BC1 gene. Another mutated form of the BC1 gene amplified from an asymptomatic, multicopy transgenic tobacco plant did not induce symptoms when transiently expressed in tobacco via a virus vector. The symptom attenuation in the transgenic tobacco by the asymptomatic BC1 may involve trans-dominant negative interference.

Amino Acid Sequence↗

PubMed1996

Early childhood supplementation does not benefit the long-term growth of stunted children in Jamaica.

The long-term benefits of early childhood supplementation and the extent to which catch-up growth occurs following linear growth retardation remain controversial. Stunted children (height-for-age < -2 SD of NCHS references, n = 122) recruited from a survey of poor neighborhoods in Kingston, Jamaica, participated in a 2-yr randomized, controlled trial of supplementation beginning at ages 9-24 mo. A group of 32 non-stunted children from the same neighborhoods was also followed. Four years after the intervention ended, when children were 7 to 8 y old, there were no effects of supplementation on any anthropometric measure. From the end of the trial until follow-up, the children who had been supplemented gained 1.2 cm less (P < 0.05) than the non-supplemented children, approximately the same amount as they had gained during the trial compared with the non-supplemented children. After adjustment for regression to the mean, the height-for-age of stunted children (supplemented and non-supplemented combined) increased from enrollment to follow-up by 0.31 Z-score (95% CI 0.17, 0.46). The height-for-age of the non-stunted children also increased (0.96 Z-score; 95% CI 0.70, 1.22). Our results suggest that some catch-up growth is possible even when children remain in poor environments. Long-term benefits of supplementation to growth may not be achieved when intervention begins after age 12 mo in children who have already become undernourished.

Anthropometry↗

PubMed1996

Relationships between wasting and linear growth in stunted children.

Height-for-age and weight-for-height are commonly used indicators of nutritional status; however, their precise interrelationship remains unclear. We examined the relationship between weight-for-height and linear growth in 127 stunted Jamaican children aged 9-24 months. The children were measured every 6 months over a 2-year period. The initial weight-for-height status was positively associated with linear growth in the following 6-month interval. The change in weight-for-height in the preceding interval was a better predictor of linear growth in the next interval than attained weight-for-height at the beginning of the interval. The results suggest that variations in weight-for-height may influence the rate of linear growth.

Age Factors↗

PubMed1995

Relationships between physical growth, mental development and nutritional supplementation in stunted children: the Jamaican study.

The relationship between physical growth and change in mental development on the Griffiths mental development scales was investigated in 127 stunted Jamaican children over a 2-year period. The role of nutritional supplementation in this relationship was examined. There were no consistent associations between changes in weight-for-height or head circumference and developmental change. Height gain over 2 years was significantly associated with change in mental age, and locomotor and hearing and speech subscale scores. Height gain in the first year predicted change in mental age, and hearing and speech in the second year. Some of the effect of supplementation on development was shared with linear growth. Therefore, nutrition probably explains part of the relationship between growth and development. However, supplementation also had effects on development independent of growth. The benefits of supplementation on development and the extent to which they were shared with growth varied among the subscales.

Body Height↗

PubMed1995

Activity and behavioral development in stunted and nonstunted children and response to nutritional supplementation.

It is frequently assumed that undernutrition in young children leads to poor development through reduced activity. 3 groups of 26 1-year-old stunted children were studied: nutritional supplementation, supplementation with psychosocial stimulation, and controls. 26 nonstunted comparison children were also studied. Activity levels were measured by extensive observation in the homes, and development using 4 subscales of the Griffith's Mental Development Scales. Initially, stunted children were less active than nonstunted ones (p < .01), but after 6 months they caught up regardless of treatment. The mental ages of the stunted children were lower than those of the nonstunted children initially, and improved with either treatment. Initially, activity levels made a significant contribution to the variance in the locomotor subscale only, but not 6 months later. Activity did not predict change in development over 6 or 12 months, nor did change in activity over 6 months predict change in development over 12 months.

Child Behavior Disorders↗

PubMed1994

Characterization and localization of mosquito-gut receptors for trypsin modulating oostatic factor using a complementary peptide and immunocytochemistry.

The gut receptor of trypsin-modulating oostatic factor (TMOF), a decapeptide hormone that regulates trypsin biosynthesis in the mosquito gut, has been characterized. The binding of TMOF to mosquito gut membranes reached maximum at pH 7.4 and 24 degrees C. No binding was observed at pH 2.5 and the binding to the membranes declined rapidly at pH 8.0. At equilibrium, maximum binding to the receptor was observed at 60 min and 24 degrees C. A synthetic complementary decapeptide NH2-Ile-Leu-Gly-Arg-Gly-Gly-Gly-Gly-Gly-Gly-COOH (FOMT) for TMOF successfully competed with the gut receptor, and specifically bound TMOF (Kd = 4 microM and Kassoc = 2.5 x 10(5) M-1). TMOF binding to gut membranes was characterized with FOMT and a specific ELISA to the hormone at 24 and 72 h after blood feeding. Two classes of binding sites were found on the gut membrane; high affinity (Kd1 = 4.6 +/- 0.7 x 10(-7) M; Kassoc = 2.2 x 10(6) M-1 Bmax = 0.1 pmol/gut) and low affinity (Kd2 = 4.43 +/- 1 x 10(-6) M; Kassoc = 2.3 x 10(5) M-1; Bmax = 0.2 pmol/gut). The total binding sites for high and low affinity classes of TMOF per gut were estimated as 6.3 x 10(10) and 1.1 x 10(11) sites, respectively. Specific binding sites on the gut increased after the blood meal and were visualized by immunocytochemical staining. These results suggest that TMOF regulates trypsin biosynthesis by binding to specific receptor sites that are located on the mosquito gut, and that this receptor can be studied using a complementary peptide approach.

Amino Acid Sequence↗

PubMed1994

Geohelminth infections in school-aged children in Jamaica.

There is concern that geohelminthiasis may adversely affect the growth and development of children. The relevance of this in the Caribbean is unclear since in many territories the prevalence of geohelminths is unknown. We report the results of three surveys conducted in Jamaican primary schools located in areas at high risk for geohelminthiasis. The first was conducted in 12 Kingston schools and comprised children in grades 2 to 5 (aged 7 to 10 years). The second and third surveys were conducted in rural areas with children in grades 2 to 5 and grades 4 and 5, respectively. Overall, 9244 children provided stool samples for analysis. The prevalence of Trichuris trichiura ranged from 42% to 47% among the surveys while that for Ascaris lumbricoides ranged from 15% to 37%. Children in grades 2 and 3 had lower T. trichiura prevalences than those in grades 4 and 5 in the first and second surveys (p < 0.05 and p < 0.005, respectively). In the second survey only, children in grades 2 and 3 had a lower prevalence of A. lumbricoides than those in grades 4 and 5 (p < 0.005). Most infections were light with approximately 1% of the sample having heavy egg densities.

Animals↗

PubMed1992

Development of specific RIA and ELISA to study trypsin modulating oostatic factor in mosquitoes.

Trypsin modulating oostatic factor (TMOF), a decapeptide (H-YDPAPPPPPP-OH) that signals the termination of trypsinlike enzyme biosynthesis in the mosquito midgut, was covalently bound to Keyhole Limpet Hemocyanin using N-hydroxysuccinimide and dicyclohexylcarbodiimide. Polyclonal antibodies raised in rabbits against this conjugate were used to develop specific RIA and enzyme linked immunosorbent assay (ELISA) to detect the peptide hormone in female Aedes aegypti. TMOF and its analogs TMOF(B) (H-DYPAPPPPPP-OH), P4 (H-YDPAPPPP-OH), P1 (H-YDPAP-OH), and poly-L-proline were tested with the antiserum. The antiserum fully recognized TMOF and partially recognized P4. Using both RIA and ELISA, we report that the amount of TMOF in the mosquito ovary is 100 +/- 20 ng (S.E.) and 96 +/- 1.4 ng (S.E.), respectively, for each assay. Minute quantities of TMOF a thousandfold lower than in the ovary were found in the mosquito brain, indicating that the hormone is probably not neural but ovarian in origin.

Aedes↗

PubMed1992

Morbidity and the growth of stunted and nonstunted children, and the effect of supplementation.

Children aged 9-24 mo were recruited by a survey of poor areas of Kingston, Jamaica. Stunted children were randomly assigned to supplementation or not. Weekly morbidity histories were taken for 2 y. Separate multiple regressions on each symptom for weight or length gain in 2-mo intervals showed significant reductions in weight gain with coughing, apathy, anorexia, diarrhea, and fever, ranging from -2.1 to -16.8 g/d ill. Apathy and diarrhea reduced gains in length (-0.26 and -0.20 mm/d ill). Significant reductions in linear growth with lower respiratory-tract infections (-0.16 mm/d ill) occurred only in nonsupplemented children. Growth over 4-mo intervals was reduced if diarrhea occurred in the first 2 mo of the interval but there were no long-term effects of apathy, fever, or anorexia. Some of the effects of morbidity on growth were therefore transient and morbidity is unlikely to be a major cause of growth retardation in this population.

Body Weight↗

PubMed1991

Nutritional supplementation, psychosocial stimulation, and mental development of stunted children: the Jamaican Study.

There is little unequivocal evidence that nutritional supplementation of undernourished children has a beneficial effect on their mental development. The effects of nutritional supplementation, with or without psychosocial stimulation, of growth-retarded (stunted) children aged 9-24 months were assessed in a study in Kingston, Jamaica. 129 children from poor neighbourhoods were randomly assigned to four groups--control, supplemented only, stimulated only, and supplemented plus stimulated. A group of matched non-stunted children (n = 32) was also included. The supplement comprised 1 kg milk-based formula per week for 2 years, and the stimulation weekly play sessions at home with a community health aide. The children's development (DQ) was assessed on the Griffiths mental development scales. Initially the stunted groups' DQs were lower than those of the non-stunted group, and those of the control group declined during the study, increasing their deficit. Stimulation and supplementation had significant independent beneficial effects on the children's development. Estimates of the supplementation effect ranged from 2.2 (95% confidence limits-1.4, 5.7) for the hand and eye subscale to 12.4 (5.4, 19.5) for the locomotor subscale and those for the stimulation effect from 6.4 (2.8, 10.0) for hand and eye to 10.3 (3.3, 17.3) for locomotor. The treatment effects were additive, and combined interventions were significantly more effective than either alone. These findings suggest that poor mental development in stunted children is at least partly attributable to undernutrition.

Female↗

PubMed1991

cDNA cloning and analysis of RNA 2 of a Prunus stem pitting isolate of tomato ringspot virus.

Recombinant plasmids containing sequences derived from the genome of a tomato ringspot virus (TomRSV) isolate associated with both stem pitting disease of stone fruits and apple union necrosis and decline were constructed. Selected inserts were subcloned into the polylinker region of the SP6 transcription vector pSP64. Using the SP6 promoter flanking this region, high specific activity 32P-labelled cRNA probes were generated by SP6 RNA polymerase. cRNA probes were specific for TomRSV RNA 2 present in purified virions or in extracts from woody and herbacous hosts. No sequence relatedness was detected between TomRSV RNA 2 and genomic RNA from tobacco ringspot, arabis mosaic, strawberry latent ringspot, or cucumber mosaic virus in Northern blot analysis using TomRSV cRNA probes. These probes detected TomRSV infection in woody and herbaceous hosts in dot-blot hybridization assays.

Cloning, Molecular↗

PubMed1991

Nutritional supplementation, psychosocial stimulation, and growth of stunted children: the Jamaican study.

The benefits of nutritional supplementation, with or without psychosocial stimulation, on the growth of stunted children were evaluated. Children aged 9-24 mo with lengths less than -2 SD of the National Center for Health Statistics references (n = 129) were randomly assigned to four groups: control, nutritional supplementation, stimulation, and both interventions. A fifth group with lengths greater than -1 SD was also enrolled. Length, weight, head and arm circumferences, and triceps and subscapular skinfold thicknesses were measured on enrollment and 6 and 12 mo later. Multiple-regression analysis was used to determine the effects of the interventions in which age, sex, initial status, initial dietary intake, and several socioeconomic variables were controlled for. Stimulation had no effect on growth and there was no interaction between the interventions. After 12 mo supplemented children had significantly increased length, weight, and head circumference (all P less than 0.01). The effects of supplementation were not cumulative but occurred in the first 6 mo.

Female↗

PubMed1991

Phenothrin lotion, the latest recruit in the battle against headlice: the results of two controlled comparative studies.

One hundred and one subjects with head louse infestation were entered into two separate studies, in which a phenothrin aqueous/alcoholic lotion was compared to a carbaryl lotion and a malathion lotion. Fifty subjects were treated with a single application of the phenothrin lotion, 28 with the carbaryl lotion and 23 with the malathion lotion. In the comparative study of the phenothrin and malathion lotions an inspection on the day following treatment showed no live lice remained, but that six of the subjects treated with malathion lotion still had evidence of viable eggs (p less than 0.05). In one subject viable eggs were still evident at two weeks post-treatment. There were no cases, however, of live lice or viable eggs at four weeks post-treatment. Mild cutaneous side-effects were reported in five subjects, the incidence of which was not significantly different by treatment group. One subject in the phenothrin and carbaryl lotion comparative study had evidence of live lice at one week post-treatment with phenothrin lotion. This subject received no further treatment and was clear of both live lice and viable eggs at subsequent visits. A separate case of live lice infestation was found at two weeks post-treatment in a subject treated with phenothrin lotion and at four weeks post-treatment in two subjects treated with carbaryl lotion. As these subjects were free of live lice infestation at previous follow-up visits it was highly probable that these were cases of re-infestation from another source.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗

PubMed1990

Results of case-control study of leukaemia and lymphoma among young people near Sellafield nuclear plant in West Cumbria.

OBJECTIVE: To examine whether the observed excess of childhood leukaemia and lymphoma near the Sellafield nuclear plant is associated with established risk factors or with factors related to the plant. DESIGN: A case-control study. SETTING: West Cumbria health district. SUBJECTS: 52 Cases of leukaemia, 22 of non-Hodgkin's lymphoma, and 23 of Hodgkin's disease occurring in people born in the area and diagnosed there in 1950-85 under the age of 25 and 1001 controls matched for sex and date of birth taken from the same birth registers as the cases. MAIN OUTCOME MEASURES: Antenatal abdominal x ray examinations, viral infections, habit factors, proximity to and employment characteristics of parents at Sellafield. RESULTS: Expected associations with prenatal exposure to x rays were found, but little information was available on viral illnesses. Relative risks for leukaemia and non-Hodgkin's lymphoma were higher in children born near Sellafield and in children of fathers employed at the plant, particularly those with high radiation dose recordings before their child's conception. For example, the relative risks compared with area controls were 0.17 (95% confidence interval 0.05 to 0.53) for being born further than 5 km from Sellafield 2.44 (1.04 to 5.71) for children of fathers employed at Sellafield at their conception, and 6.42 (1.57 to 26.3) for children of fathers receiving a total preconceptual ionising radiation dose of 100 mSv or more. Other factors, including exposure to x rays, maternal age, employment elsewhere, eating seafood, and playing on the beach did not explain these relationships. Focusing on Seascale, where the excess incidence has predominantly been reported, showed for the four out of five cases of leukaemia and one case of non-Hodgkin's lymphoma whose fathers were employed at Sellafield and for whom dose information was obtained that the fathers of each case had higher radiation doses before their child's conception than all their matched control fathers; the father of the other Seascale case (non-Hodgkin's lymphoma) was not employed at the plant. These results seem to explain statistically the geographical association. For Hodgkin's disease neither geographical nor employment associations with Sellafield were found. CONCLUSIONS: The raised incidence of leukaemia, particularly, and non-Hodgkin's lymphoma among children near Sellafield was associated with paternal employment and recorded external dose of whole body penetrating radiation during work at the plant before conception. The association can explain statistically the observed geographical excess. This result suggests an effect of ionising radiation on fathers that may be leukaemogenic in their offspring, though other, less likely, explanations are possible. There are important potential implications for radiobiology and for protection of radiation workers and their children.

Case-Control Studies↗

PubMed1990

Methods and basic data of case-control study of leukaemia and lymphoma among young people near Sellafield nuclear plant in West Cumbria.

Case-Control Studies↗

PubMed1990

Dietary intake and observed activity of stunted and non-stunted children in Kingston, Jamaica. Part II: Observed activity.

It is generally believed that activity levels are reduced in poorly nourished children. This may conserve energy, but may have a detrimental effect on mental development. However there are few data which support this hypothesis. No previous studies were found which looked at the activity levels of stunted children. In this study we modified the time and motion observation methods of Torun (1984) by using recording periods of 1 instead of 10 min. This significantly reduced the estimated time spent by young children in moderate and vigorous activities. Four hours of observing young children while they were awake, using the modified method, produced highly reliable data. The activity levels of a subsample of children described in part I were observed. The children were aged 12-24 months and were observed for 4 h on 2 d. Seventy-eight stunted children (height less than -2 SD of median, NCHS) were compared with 26 non-stunted children (height greater than -1 SD). The stunted children were significantly less active than the non-stunted children, although the difference in activity rating was small (3.4 per cent). They spent more time in light activities (P less than 0.001) and less time in moderate or vigorous activities (P less than 0.01). Both groups slept a similar amount. Using Torun's values for the energy cost of activities it appears unlikely that the reduced activity would conserve energy to a great extent, but it may still be of biological importance, since it is comparable to the energy cost of growth at this age. Activity levels increased with age but were not significantly related to weight for height.(ABSTRACT TRUNCATED AT 250 WORDS)

Child, Preschool↗

PubMed1990

Dietary intakes and activity levels of stunted and non-stunted children in Kingston, Jamaica. Part 1. Dietary intakes.

The dietary intakes of stunted and non-stunted children were measured on enrollment to a longitudinal study of growth and development. Children aged 9-24 months were recruited by house to house survey of several poor areas of Kingston. All children with height for age less than -2 SD of the NCHS standards and weight for height below the standard median were enrolled. Alternate stunted children were matched for age and sex with the non-stunted child (height for age greater than -1 SD) living nearest. Dietary information was obtained by two 24-h recalls. Mean trainer-interviewer reliability was greater than 90 per cent throughout the study. Correlation between energy intakes on the 2 days was 0.68 (P less than 0.001). Stunted children had a significantly less varied diet, fewer dairy products and fruit than non-stunted children. Protein intakes met requirements. Energy intakes were similar in both groups and approximately 200 kcal below the recommended intake. Energy and protein intakes per kg were significantly higher in the stunted children than in non-stunted children (energy P less than 0.001, protein P less than 0.005). Greater morbidity in the stunted children could account for some, but not all, of this difference. Children with lower weight for height had lower intakes (energy P less than 0.05, protein P less than 0.01). Intakes were greater in children who lived in better housing, with more household possessions and whose mothers had more skilled occupations. Good reliability and the above associations indicate that the data are valid.

Child Development↗