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Biomedical subjects

David Davies

Publications and source records attributed to David Davies.

13 recordsLinked to original sources
PubMed2006

Reproducibility of measurements of inspiratory work capacity in cystic fibrosis patients.

The evaluation of respiratory muscle endurance (RME) is regarded as being clinically relevant to the assessment of respiratory muscle function. The reproducibility of a non-invasive measure of assessing RME was determined by measuring inspiratory work capacity (IWC) (using a computerised system). Measurements were obtained on two occasions in 20 adult cystic fibrosis (CF) patients (22.7+/-3.4 years, mean+/-S.D.) and 20 age (23.4+/-4.4 years) and gender (10 male, 10 female in each group) matched healthy controls. The coefficients of reliability (CR), intra-class correlation coefficients (ICC) and limits of agreement (bias+/-2 S.D.) were determined. CR values for the CF patients and controls were above 90% and with ICC of 0.99 in both CF patients and controls. The differences in IWC between study days were within +/-2 S.D. of the mean difference in all but one CF and one control subject. These data suggest that measures of IWC may be considered reliable when used to assess RM function in both controls and in patients with CF.

Adult↗
PubMed2005

Long term effect of breast feeding: cognitive function in the Caerphilly cohort.

STUDY OBJECTIVE: There is evidence suggesting that artificial feeding is associated with a reduction in cognitive function in infants and children, in contrast with breast feeding, but the available evidence suffers from confounding by social and educational factors. An opportunity arose in the Caerphilly cohort study to examine relations between cognitive function in older men and their feeding as infants, when breast feeding was usual. DESIGN: A prospective cohort study. SETTING: Caerphilly, South Wales, UK, was a deprived coal mining community when the men had been born in 1920-35. Most had been breast fed as infants. PARTICIPANTS: 779 men aged 60-74 years when tested. The men had earlier been asked to obtain from their mothers their birth weight, and how they had been fed as infants. RESULTS: Complete data were obtained for 779 men. In those whose birth weight had been at or above the median, the adjusted mean cognitive function was only slightly and non-significantly lower in those who had been artificially fed. In the men whose birth weight had been below the median, having been artificially fed was associated with significantly lower results in both a test of reasoning (the AH4) and word power (the national adult reading test (NART)). Two standard deviations below the median birth weight, artificial feeding was associated with a reduction of six points (70% of a SD) on word power (the NART). CONCLUSIONS: In men whose birth weight had been low, having been artificially fed is associated with poorer cognitive function in late adult life.

Aged↗
PubMed2005

Prenatal and postnatal milk supplementation and adult insulin-like growth factor I: long-term follow-up of a randomized controlled trial.

OBJECTIVE: Insulin-like growth factors (IGF) are increasingly recognized as important determinants of adult health, in particular risk of certain cancers. However, little is known about the determinants of adult IGFs and to what degree they may be programmed by early life influences. DESIGN: Randomized controlled trial of prenatal and postnatal milk supplementation among 951 subjects born in 1972 to 1974 in South Wales. MAIN OUTCOME MEASURE: Measures of IGF-I, IGF binding protein 3, and the molar ratio. RESULTS: Data on adult IGFs were available from 663 subjects at a mean age of 25 years. Subjects in the intervention arm had lower IGF-I (-8.5 ng/mL; 95% confidence interval, -15.1 to -1.8, P = 0.01) and ratio (-1.20; 95% confidence interval, -2.33 to -0.04, P = 0.04). These differences could not be explained by follow-up bias or confounding factors. CONCLUSIONS: These results provide experimental data on the role of early life programming either in the intrauterine or postnatal period that may have long-term influences on the IGF axis, with potential implications for disease risk.

Adult↗
PubMed2005

Consistent pulmonary and systemic responses from inhalation of fine concentrated ambient particles: roles of rat strains used and physicochemical properties.

Several studies have reported health effects of concentrated ambient particles (CAP) in rodents and humans; however, toxicity end points in rodents have provided inconsistent results. In 2000 we conducted six 1-day exposure studies where spontaneously hypertensive (SH) rats were exposed to filtered air or CAPs (< or = 2.5 microm, 1,138-1,765 microg/m3) for 4 hr (analyzed 1-3 hr afterward). In seven 2-day exposure studies in 2001, SH and Wistar Kyoto (WKY) rats were exposed to filtered air or CAP (< or = 2.5 microm, 144-2,758 microg/m3) for 4 hr/day times 2 days (analyzed 1 day afterward). Despite consistent and high CAP concentrations in the 1-day exposure studies, no biologic effects were noted. The exposure concentrations varied among the seven 2-day exposure studies. Except in the first study when CAP concentration was highest, lavageable total cells and macrophages decreased and neutrophils increased in WKY rats. SH rats demonstrated a consistent increase of lavage fluid gamma-glutamyltransferase activity and plasma fibrinogen. Inspiratory and expiratory times increased in SH but not in WKY rats. Significant correlations were found between CAP mass (microgram per cubic meter) and sulfate, organic carbon, or zinc. No biologic effects correlated with CAP mass. Despite low chamber mass in the last six of seven 2-day exposure studies, the levels of zinc, copper, and aluminum were enriched severalfold, and organic carbon was increased to some extent when expressed per milligram of CAP. Biologic effects were evident in those six studies. These studies demonstrate a pattern of rat strain-specific pulmonary and systemic effects that are not linked to high mass but appear to be dependent on CAP chemical composition.

Air Pollutants↗
PubMed2004

Lack of support for a role of the insulin gene variable number of tandem repeats minisatellite (INS-VNTR) locus in fetal growth or type 2 diabetes-related intermediate traits in United Kingdom populations.

The insulin gene variable number of tandem repeats minisatellite (INS-VNTR) class III allele is associated with altered fetal growth, type 2 diabetes risk (especially when paternally inherited), and insulin and IGF2 gene expression. Further studies are needed to establish the role of the INS-VNTR in fetal growth and assess whether its effects depend on the parent of origin. We analyzed the INS-VNTR-linked -23 Hph1 polymorphism in 2283 subjects, comprising 1184 children and 1099 parents. There were no differences (P < 0.05) in birth weight between offspring of the three genotypes: III/III (n = 108) vs. I/I (n = 558), effect size, -8 g (P = 0.87); and I/III (n = 464) vs. I/I, effect size, -19 g (P = 0.54). We observed no differences in head circumference [III/III (n = 95) vs. I/I (n = 470), effect size, -0.14 cm; P = 0.31] or birth length. No differences were observed when stratifying by postnatal growth realignments [nonchangers III/III (n = 37) vs. I/I (n = 170), effect size, -43 g; P = 1.00] or by parent of origin of the class III allele (presence of paternal III allele effect size, -15 g; P = 0.74). INS-VNTR was nominally associated (P < 0.05) with body mass index and insulin resistance, but not with beta-cell function, in young adults. In the largest study to date, we found a lack of support for a role for INS-VNTR in fetal growth and nominal association with type 2 diabetes-related intermediate traits.

Adult↗
PubMed2002

A putative functional polymorphism in the IGF-I gene: association studies with type 2 diabetes, adult height, glucose tolerance, and fetal growth in U.K. populations.

IGF-I has a critical role in growth and metabolism. A microsatellite polymorphism 1 kb upstream to the IGF-I gene has recently been associated with several adult phenotypes. In a large Dutch cohort, the absence of the commonest allele (Z) was associated with reduced serum IGF-I levels, reduced height, and an increased risk of type 2 diabetes and myocardial infarction. This result has not been replicated, and the role of this polymorphism in these traits in U.K. subjects is not known. We sought further evidence for the involvement of this variant in type 2 diabetes using a case-control study and IGF-I and diabetes-related traits in a population cohort of 640 U.K. individuals aged 25 years. Absence of the common allele was not associated with type 2 diabetes (odds ratio 0.70, 95% CI 0.47-1.04 for X/X versus Z/Z genotype, chi(2) test for trend across genotypes, P = 0.018). In the population cohort, the common allele (Z) was associated with decreased IGF-I levels (P = 0.01), contrary to the Dutch study, but not with adult height (P = 0.23), glucose tolerance (P = 0.84), oral glucose tolerance test-derived values of beta-cell function (P = 0.90), or insulin resistance (P = 0.66). There was no association with measures of fetal growth, including birth weight (P = 0.17). Our results do not support the previous associations and suggest that the promoter microsatellite is unlikely to be functionally important.

Adult↗
PubMed2002

Detection of Norwalk-like virus infection aboard two U.S. Navy ships.

Two U.S. Navy ships experienced outbreaks of gastroenteritis following port visits to Southeast Asia during August to September 1999. The USS Peleliu (LHA 5) had 162 (6% attack rate) medical visits and the USS Constellation (CV 64) had 425 medical visits (9% attack rate). Navy Environmental and Preventive Medicine Unit No. 5 personnel conducted on-board molecular diagnostic assays to presumptively detect the presence of genogroup I Norwalk-like viruses (NLV) in both outbreaks. NLV RNA were detected in 4 (80%) of 5 Peleliu stool specimens and in 9 (36%) of 25 from the Constellation. Significant antibody titer rises to NLV antigens were measured in 18 (62%) of 29 Peleliu and 69 (68%) of 102 Constellation cases, but only in 1 (4%) of 28 asymptomatic controls. All environmental swipes were negative for NLV. Stools yielded no bacterial or parasitic enteropathogens. No point source was found for either ship. The on-site laboratory investigation can provide important information for outbreak control and prevention while new cases are still presenting.

Adult↗
PubMedDate not supplied

Immunochemical-based method for detection of hazelnut proteins in processed foods.

A competitive enzyme-linked immunosorbent assay (ELISA) was developed to detect hazelnut by using polyclonal antibodies generated against a protein extract of roasted hazelnut. No cross-reactivity was observed in tests against 39 commodities, including many common allergens, tree nuts, and legumes. Hazelnut protein standard solutions at 0.45 ng/mL [inhibition concentration (IC80) of the competitive test] were clearly identified by the ELISA. An extraction and quantification method was developed and optimized for chocolate, cookies, breakfast cereals, and ice cream, major food commodities likely to be cross-contaminated with undeclared hazelnut during food processing. No sample cleanup was required when extracts were diluted 10-fold. Recovery results were generated with blank matrixes spiked at 4 levels from 1 to 10 microg/g hazelnut protein. With the developed extraction and sample handling procedure, hazelnut proteins were recovered at 64-83% from chocolate and at 78-97% from other matrixes. A confirmatory technique was developed with sodium dodecyl sulfate-polyacrylamide gel electrophoresis and Western transfer. The developed methods were applied to a small market survey of chocolate products and allowed the identification of undeclared hazelnut in these products.

Enzyme-Linked Immunosorbent Assay↗
PubMedDate not supplied

Regulatory and compliance activities to protect food-allergic consumers in Canada: research in support of standard setting and consumer protection.

An overview is presented of the activities of Health Canada and the Canadian Food Inspection Agency (CFIA) in the area of food allergens. Since the 1990s, changes were made in the Food and Drug Regulations in order to better protect allergic consumers by imposing labeling requirements to clearly identify sources of priority food allergens in prepackaged foods. Policies of application as well as risk management strategies are discussed with some statistics on allergen-related food recalls in Canada for the years 1997--2001. Health Canada's allergen method development program is a pioneering research initiative that was developed in the early 1990s in support of the changing Canadian regulatory environment. The objectives and some of the accomplishments of this program are presented. The development of the Canadian Compendium of Allergen Methodologies under a Web-based application to compile data on evaluated allergen detection methods will provide further support to compliance activities nationally, as well as to the international analytical community in both government and the food industry. Some emerging techniques for the confirmation of results generated by enzyme-linked immunosorbent assays are also discussed.

Allergens↗