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Biomedical subjects

J Dykes

Publications and source records attributed to J Dykes.

16 recordsLinked to original sources
PubMed2004

Socioeconomic gradient in body size and obesity among women: the role of dietary restraint, disinhibition and hunger in the Whitehall II study.

OBJECTIVE: To examine the associations between three psychological eating behaviour variables--restraint, hunger and disinhibition--and body weight and size, and to assess their explanatory power for the employment grade gradients in body measurement. DESIGN: Cross-sectional analysis of self-report and clinical data. SUBJECTS: : In all, 1470 women (aged 45-68 y, mean 56.3, s.d. 6.0 y), body mass index (BMI) 26.3 (4.8) kg/m(2) at phase 5 (1997-98) of the Whitehall II study. MEASUREMENTS: Employment grade was measured in six bands ranging from clerical (lowest) to administrative (highest). Five measures of body size were examined: BMI, weight in kilograms, waist and hip measurement in centimetres and waist-hip ratio. The eating behaviour variables were measured using Stunkard and Messick's (1985) Three-Factor Eating Questionnaire (TFEQ). RESULTS: Disinhibition and hunger scores were strongly and directly associated with all measures of body weight and size. Restraint score was not directly associated with body size and weight. An interaction between restraint and disinhibition scores was found. The low-restraint-high-disinhibition group (based on median score splits) were the heaviest (BMI 28.5 kg/m(2)) and largest (waist 85.8 cm), while the low-restraint-low-disinhibition group were the lightest (BMI 24.2 kg/m(2)) and smallest (waist 76.3 cm). Employment grade gradients in body weight and size remained largely unchanged after adjustment for dietary restraint. Moderate attenuations were found for disinhibition scores (3.6-15.0%) and hunger (4.8-19.9%) on the five body-size measures. CONCLUSION: Among middle-aged women high scores on hunger and disinhibition, as measured by the TFEQ, are associated with greater body size. Restraint relates to body size through its interaction with disinhibition. Individuals with high disinhibition and any level of restraint are heavier and larger than those with low levels of disinhibition. High disinhibition coupled with low levels of restraint is associated with the greatest weight and size. Hunger and disinhibition explain a moderate amount of the gradient in body size across employment grade and may be useful concepts for future work on the socio-economic gradient in obesity and overweight.

Aged↗
PubMed2002

A pooled analysis of 10 case-control studies of melanoma and oral contraceptive use.

Data regarding the effects of oral contraceptive use on women's risk of melanoma have been difficult to resolve. We undertook a pooled analysis of all case-control studies of melanoma in women completed as of July 1994 for which electronic data were available on oral contraceptive use along with other melanoma risk factors such as hair colour, sun sensitivity, family history of melanoma and sun exposure. Using the original data from each investigation (a total of 2391 cases and 3199 controls), we combined the study-specific odds ratios and standard errors to obtain a pooled estimate that incorporates inter-study heterogeneity. Overall, we observed no excess risk associated with oral contraceptive use for 1 year or longer compared to never use or use for less than 1 year (pooled odds ratio (pOR)=0.86; 95% CI=0.74-1.01), and there was no evidence of heterogeneity between studies. We found no relation between melanoma incidence and duration of oral contraceptive use, age began, year of use, years since first use or last use, or specifically current oral contraceptive use. In aggregate, our findings do not suggest a major role of oral contraceptive use on women's risk of melanoma.

Adolescent↗
PubMed2002

Socio-economic and ethnic influences on infant feeding practices related to oral health.

OBJECTIVE: To assess the role of socio-economic factors in explaining ethnic differences in two infant feeding practices contra-indicated for dental health: adding sugary foods to a feeding bottle and bottle usage for any type of drink after one year. DESIGN: Secondary analysis of dietary and socio-demographic data from the Office of National Statistics (ONS) survey of infant feeding in Asian families. Regression models examining the impact of ethnicity on the two feeding practices were compared with models which also included eight socio-economic variables. SAMPLE: The ONS survey collected data from a representative sample of minority ethnic groups living in the UK. The sample consisted of 764 Indian, 593 Pakistani, and 477 Bangladeshi families and 548 White families by the final stage of the study. RESULTS: Significant socio-economic differences were identified between the different ethnic groups in the sample. The Bangladeshi group were the most disadvantaged and deprived group. Regression analyses showed that inclusion of socio-economic variables added significantly to models based solely on ethnicity for the two selected feeding practices. There was a considerable drop in the odds ratios for ethnicity when socioeconomic variables were included in models for adding sugary foods to the bottle. However, this effect was less evident in models predicting bottle usage at fifteen months. CONCLUSION: While ethnicity may influence infant feeding practices, when socio-economic factors are considered it appears to be a less important determinant for some of these behaviours.

Bangladesh↗
PubMed2001

Two-stage methods for the analysis of pooled data.

Epidemiologic studies of disease often produce inconclusive or contradictory results due to small sample sizes or regional variations in the disease incidence or the exposures. To clarify these issues, researchers occasionally pool and reanalyse original data from several large studies. In this paper we explore the use of a two-stage random-effects model for analysing pooled case-control studies and undertake a thorough examination of bias in the pooled estimator under various conditions. The two-stage model analyses each study using the model appropriate to the design with study-specific confounders, and combines the individual study-specific adjusted log-odds ratios using a linear mixed-effects model; it is computationally simple and can incorporate study-level covariates and random effects. Simulations indicate that when the individual studies are large, two-stage methods produce nearly unbiased exposure estimates and standard errors of the exposure estimates from a generalized linear mixed model. By contrast, joint fixed-effects logistic regression produces attenuated exposure estimates and underestimates the standard error when heterogeneity is present. While bias in the pooled regression coefficient increases with interstudy heterogeneity for both models, it is much smaller using the two-stage model. In pooled analyses, where covariates may not be uniformly defined and coded across studies, and occasionally not measured in all studies, a joint model is often not feasible. The two-stage method is shown to be a simple, valid and practical method for the analysis of pooled binary data. The results are applied to a study of reproductive history and cutaneous melanoma risk in women using data from ten large case-control studies.

Adolescent↗
PubMed2001

Exploratory visualization software for reporting environmental survey results.

Environmental surveys yield three principal products: maps, a set of data tables, and a textual report. The relationships between these three elements, however, are often cumbersome to present, making full use of all the information in an integrated and systematic sense difficult. The published paper report is only a partial solution. Modern developments in computing, particularly in cartography, GIS, and hypertext, mean that it is increasingly possible to conceive of an easier and more interactive approach to the presentation of such survey results. Here, we present such an approach which links map and tabular datasets arising from a vegetation survey, allowing users ready access to a complex dataset using dynamic mapping techniques. Multimedia datasets equipped with software like this provide an exciting means of quick and easy visual data exploration and comparison. These techniques are gaining popularity across the sciences as scientists and decision-makers are presented with increasing amounts of diverse digital data. We believe that the software environment actively encourages users to make complex interrogations of the survey information, providing a new vehicle for the reader of an environmental survey report.

Conservation of Natural Resources↗
PubMed2001

Socio-economic determinants of selected dietary indicators in British pre-school children.

OBJECTIVES: To assess the proportion of pre-school children meeting reference nutrient intakes (RNIs) and recommendations for daily intakes of iron, zinc, vitamins C and A, and energy from non-milk extrinsic sugars. To assess whether meeting these five dietary requirements was related to a series of socio-economic variables. DESIGN: Secondary analysis of data on daily consumption of foods and drinks from the National Diet and Nutrition Survey (NDNS) of children aged 1.5-4.5 years based on 4-day weighed intakes. SUBJECTS: One thousand six hundred and seventy-five British pre-school children aged 1.5-4.5 years in 1993. RESULTS: Only 1% of children met all five RNIs/recommendations examined; 76% met only two or fewer. Very few children met the recommendations for intakes of zinc (aged over four years) and non-milk extrinsic sugars (all ages). The number of RNIs/recommendations met was related to measures of socio-economic class. Children from families in Scotland and the North of England, who had a manual head of household and whose mothers had fewest qualifications, met the least number of RNIs/recommendations. CONCLUSIONS: Very few pre-school children have diets that meet all the RNIs and recommendations for iron, zinc, vitamins C and A, and energy from non-milk extrinsic sugars. Dietary adequacy with respect to these five parameters is related to socio-economic factors. The findings emphasise the need for a range of public health policies that focus upon the social and economic determinants of food choice within families.

Ascorbic Acid↗
PubMed2000

Preschool children's consumption of drinks: implications for dental health.

OBJECTIVE: To examine drinking patterns in pre-school children and their relationship to percentage of energy intake from non-milk extrinsic sugars. DESIGN: Secondary analysis of data from the national diet and nutrition survey (NDNS) relating to the dietary intakes of a representative sample of pre-school children in the UK. SUBJECTS: 1,675 children aged 1.5 to 4.5 years surveyed between July 1992 and June 1993. OUTCOME MEASURES: Proportion of consumers, average daily frequency of consumption and estimated seven day volume of consumption of different drinks. Percentage of average daily energy intake obtained from non-milk extrinsic sugars (NMES). RESULTS: Soft drinks were the most commonly consumed drinks followed by whole milk and diet or low sugar varieties of soft drinks. Half the sample were estimated to consume more than 1.5 litres of soft drinks and whole milk and over a litre of diet or low-sugar soft drinks per seven days. Fifty-six per cent of the children consumed soft drinks more than once a day. The youngest children (1.5-2.5 years) were more likely to consume whole milk and less likely to consume diet, soft drinks and skimmed milk than other age groups. Children from manual home backgrounds consumed more tea and coffee and were less likely to consume fruit juice than those from non-manual backgrounds. Drinks contributed 23% to total energy intake and 39% of NMES intake. Consumption of soft drinks, fruit juice and whole and semi-skimmed milk accounted for 59% of variance in percentage of energy from NMES. CONCLUSIONS: A large proportion of pre-school children consume considerable quantifies of soft drinks which have little or no nutritional value and are high in cariogenic non-milk extrinsic sugars. This has implications for children's dental and general health. Recommendations for drinks consumption should be included in food policy guidelines for pre-school children.

Age Factors↗
PubMed1999

Immunogenicity of 2 serogroup B outer-membrane protein meningococcal vaccines: a randomized controlled trial in Chile.

CONTEXT: Meningococcal disease occurs worldwide, and serogroup B disease accounts for a large proportion of cases. Although persons younger than 4 years are at greatest risk for serogroup B meningococcal disease, vaccine efficacy has not been demonstrated in this age group. OBJECTIVE: To evaluate serum bactericidal activity (SBA) against homologous vaccine type strains and a heterologous Chilean epidemic strain of Neisseria meningitidis as a potential correlate for vaccine efficacy. DESIGN: Double-blind, randomized controlled trial conducted between March 14 and July 20, 1994. All blood samples were taken by December 1994. SETTING: Santiago, Chile, where a clonal serogroup B meningococcal disease epidemic began in 1993. PARTICIPANTS: Infants younger than 1 year (n = 187), children aged 2 to 4 years (n = 183), and adults aged 17 to 30 years (n = 173). INTERVENTION: Participants received 3 doses of outer-membrane protein (OMP) meningococcal vaccine developed in either Cuba or Norway or a control vaccine, with each dose given 2 months apart. Blood samples were obtained at baseline, prior to dose 3, and at 4 to 6 weeks after dose 3. MAIN OUTCOME MEASURE: Immune response, defined as a 4-fold or greater rise in SBA titer 4 to 6 weeks after dose 3 compared with prevaccination titer. RESULTS: Children and adult recipients of either meningococcal vaccine were more likely than controls to develop an immune response to the heterologous epidemic strain. After 3 doses of vaccine, 31% to 35% of children responded to the vaccine vs 5% to placebo; 37% to 60% of adults responded to vaccine vs 4% to placebo (P<.05 vs control for all). Infants, however, did not respond. In contrast, against homologous vaccine type strains, the response rate was 67% or higher among children and adults and 90% or higher among infants (P<.001 vs control for all). Subsequent SBA against 7 isogenic homologous target strains identified class 1 OMP as the immunodominant antigen. CONCLUSIONS: These data suggest that neither serogroup B OMP meningococcal vaccine would confer protection during a heterologous epidemic. However, epidemic strain-specific vaccines homologous for class 1 OMP are promising candidates for the control of epidemic serogroup B meningococcal disease.

Adolescent↗
PubMed1998

Immunogenicity of two efficacious outer membrane protein-based serogroup B meningococcal vaccines among young adults in Iceland.

Serum bactericidal activity (SBA) and ELISA antibody levels elicited by two efficacious serogroup B meningococcal vaccines were measured in a controlled trial involving 408 15- to 20-year-olds. Subjects were given two doses at a 6-week interval of a serogroup B or control vaccine. Response was defined as > or = 4-fold rise in antibody level. After two doses of the Finlay Institute (Havana) vaccine at 12 months, the proportions of SBA and ELISA responders were not different from those of the control group (15% and 17% [vaccine] vs. 13% and 9% [control], P > .05). After two doses of the National Institute of Public Health (Oslo) vaccine, there were more SBA and ELISA responders than in the control group (47% and 34% [vaccine] vs. 10% and 1% [control]) or the Finlay Institute vaccine group (P < .05 for both). SBA and ELISA may be insensitive correlates for protective efficacy for some outer membrane protein-based serogroup B meningococcal vaccines.

Adolescent↗
PubMed1997

Standardization of an opsonophagocytic assay for the measurement of functional antibody activity against Streptococcus pneumoniae using differentiated HL-60 cells.

Host protection against pneumococcal disease i primarily mediated by phagocytosis. We developed and standardized an opsonophagocytic assay using HL-60 cells (human promyelocytic leukemia cells). Fifty-five serum samples were analyzed for the presence of functional antibody against seven pneumococcal serogroups or serotypes (4, 6B, 9V, 14, 18C, 19F, and 23F) by using differentiated HL-60 cells (granulocytes) and peripheral blood leukocytes (PBLs). Six of the 55 serum samples were from unvaccinated adult volunteers, 31 serum samples were from adults who received one dose of the 14-valent or the 23-valent polysaccharide vaccine, and 18 serum samples were from 16-month-old infants who received four doses of an investigational 7-valent polysaccharide-protein conjugate vaccine. The results of an opsonophagocytic assay with HL-60 cells correlated highly with those of an assay with PBLs as effector cells (median r for seven serotypes = 0.87: P < 0.01). Opsonophagocytic titers were compared with the immunoglobulin G antibody concentrations determined by enzyme-linked immunosorbent assay (ELISA). The r values for serogroups or serotypes 4, 6B, 9V, 14, 18C, 19F, and 23F were 0.61, 0.60, 0.67 0.90, 0.61, 0.39, and 0.57, respectively, when HL-60 cells were used as effector cells and 0.56, 0.47, 0.61, 0.90, 0.71, 0.31, and 0.62, respectively, when PBLs were used. The assay requires small amounts of serum (40 microliters per serotype), making this test suitable for assaying infant sera. Culturable cells aid in assay standardization and likely reduce donor-to-donor variability. This standardized assay, in combination with the standardized ELISA, can be used to evaluate current and developing pneumococcal vaccines, in which functional opsonophagocytic antibody activity may correlate with protection against pneumococcal disease.

Adult↗
PubMed1995

Assignment of Neisseria meningitidis serogroup A and C class-specific anticapsular antibody concentrations to the new standard reference serum CDC1992.

A new standard meningococcal reference serum designated CDC1992 was prepared to replace meningococcal reference sera ECG and PB-2, which are not available in sufficient quantities for continued use as primary reference sera. CDC1992 was prepared from 14 healthy adult volunteers who underwent plasmapheresis 4 to 12 weeks postvaccination with a single dose of a Neisseria meningitidis quadrivalent polysaccharide vaccine. Total and/or class-specific meningococcal serogroup A and C anticapsular antibody concentrations (in micrograms per milliliter) were assigned to CDC1992 by using homologous and heterologous enzyme-linked immunosorbent assay (ELISA) formats. The reference serum ECG was used as a reference standard to assign total anticapsular antibody concentrations to CDC1992 by a homologous ELISA format. A heterologous ELISA format, with the Haemophilus influenzae type b standard reference serum FDA 1983, was used to assign total and class-specific antibody concentrations to CDC1992. Alkaline phosphatase-labeled mouse anti-human monoclonal antibody conjugates were used as secondary antibodies in both ELISA formats. The total, immunoglobulin G (IgG), IgA, and IgM antibody concentrations, assigned to CDC1992 for serogroup A were 135.8, 91.8, 20.1, and 23.9 micrograms/ml, respectively, and those for serogroup C were 32.0, 24.1, 5.9, and 2.0 micrograms/ml, respectively. Meningococcal serogroup A and C antibody concentrations were in good agreement when homologous and heterologous ELISA format results were compared. Total and class-specific serogroup A and C antibody concentrations were determined in six adult quality control serum samples from the Centers for Disease Control and Prevention by using the homologous ELISA and our assigned antibody concentrations for CDC1992. Antibody concentrations in reference sera ECG and PB-2 were measured in order to provide a historical link to previous studies. The general acceptance of CDC1992 as the standard reference serum and the assigned antibody concentrations will allow investigators to compare antibody levels in serum to those in a single reference preparation.

Adult↗
PubMed1991

Stressors and rewards of being an AIDS emotional-support volunteer: a scale for use by care-givers for people with AIDS.

This study describes scales which can be used to identify the levels of stress and reward associated with being a AIDS emotional-support volunteer. Four categories of stressors were identified. These were 'emotional overload', 'client problems', 'lack of support' and 'lack of training'. The reward categories were 'personal effectiveness', 'emotional support', 'social support' and 'empathy/self-knowing'. There were low, but positive correlations between these stressor scales and other measures of psychological morbidity, the 28-item General Health Questionnaire (GHQ) and the Maslach Burnout Inventory (MBI). Levels of stress and reward were positively correlated and, taken together, the scales may be of use as a measure of the degree of involvement of volunteers in the AIDS care-giving process. Although these scales were derived from items provided from AIDS emotional-support volunteers many of the items may also be relevant to other health workers providing care for people with AIDS.

Acquired Immunodeficiency Syndrome↗
PubMed1984

Aerobic microbial degradation of glucoisosaccharinic Acid.

alpha-Glucoisosaccharinic acid (GISA), a major by-product of kraft paper manufacture, was synthesized from lactose and used as the carbon source for microbial media. Ten strains of aerobic bacteria capable of growth on GISA were isolated from kraft pulp mill environments. The highest growth yields were obtained with Ancylobacter spp. at pH 7.2 to 9.5. GISA was completely degraded by cultures of an Ancylobacter isolate. Ancylobacter cell suspensions consumed oxygen and produced carbon dioxide in response to GISA addition. A total of 22 laboratory strains of bacteria were tested, and none was capable of growth on GISA. GISA-degrading isolates were not found in forest soils.

Journal Article↗
PubMed1983

Does 111indium-platelet deposition predict patency in prosthetic arterial grafts?

The relationship between the rate of 111In-platelet deposition on vascular grafts and subsequent thrombosis has been examined in patients undergoing femoropopliteal by-pass. Sixty-seven patients undergoing femoropopliteal by-pass using vein, Dacron or PTFE were randomized to aspirin plus dipyridamole (ASA/DPM) or placebo. Autologous 111In-platelets were injected in the second postoperative week and Thrombogenicity Index (TI) calculated as the mean daily rise in the ratio of radioactivity graft/contralateral thigh. Graft patency was assessed to 1 year. Mean (+s.e.m.) TI at 1 week in 21 grafts that occluded within 12 months was 0.19 +/- 0.018 compared with 0.07 +/- 0.009 in the 38 that remained patient (P less than 0.001). Grafts with a TI less or greater than the median had a 90 per cent or 39 per cent cumulative 1-year patency, respectively (P less than 0.001). In the prosthetic grafts ASA/DPM reduced mean TI from 0.17 +/- 0.02 to 0.11 +/- 0.01 (P less than 0.02) and enhanced 1-year patency from 36 to 67 per cent (P less than 0.05). Following femoropopliteal by-pass TI related to subsequent graft patency. Radiolabelled platelet deposition therefore provides a guide as to how new materials or antithrombotic drugs may influence clinical graft thrombosis. Platelet inhibition reduced both graft thrombogenicity and subsequent occlusion.

Aspirin↗