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Biomedical subjects

M Blair

Publications and source records attributed to M Blair.

At least 19 recordsLinked to original sources
PubMed2006

Bioavailability of vitamin A sources for cattle.

An experiment was conducted to evaluate the bioavailability of 5 sources of vitamin A. It was hypothesized that some vitamin A products have protective coatings that are more resistant than others to rumen destruction and that such protection would result in greater tissue concentrations of vitamin A. Fifty-three yearling Angus x Brahman cattle, consisting of 39 steers and 14 heifers, were stratified by BW and sex and randomly assigned to 6 high-concentrate diet groups receiving no vitamin A supplementation (control) or vitamin A supplemented from the following sources: Microvit A (Adisseo, Acworth, GA), Rovamix A (DSM, Parsippany, NJ), Sunvit A, Lutavit A, and Microvit A DLC (Adisseo). The vitamin A treatment groups were fed daily 80,000 IU of retinol/animal in a low-retinol concentrate diet (78.5% oats, 10% cottonseed hulls, 8% molasses, and 2% cottonseed meal; DM basis) and a free-choice, poor quality (low carotene) hay for 84 d. Every 28 d, BW was determined and liver biopsies and plasma were collected and analyzed for retinol concentrations. All retinol treatments showed significant increases in liver retinol concentrations compared with control animals (P < 0.0001), which steadily decreased over time. At all collection times, Microvit A led to numerically, but not significantly, greater concentrations of retinol in liver than did all other treatments. However, at the end of the experiment, there was no significant difference in liver retinol concentration among Microvit A, Rovamix A, Lutavit A, and Microvit A DLC diets. When liver retinol concentrations at all collection times were considered, Microvit A and Rovamix A appeared to provide the most bioavailable vitamin A.

Animal Feed↗
PubMed2006

Poult performance as influenced by age of dam, genetic line, and dietary vitamin E.

An experiment was conducted to measure the effects of age of dam, genetic line, and dietary levels of vitamin E on growth and immunocompetence of poults. Age of dam was defined as younger (in early egg production) and older (past peak production); line consisted of a commercial sire and dam line; and dietary vitamin E was supplemented into the diet at 10 and 300 IU/kg of feed. Traits measured included body, liver, gizzard, and yolk sac weights at hatch; BW and feed conversion to 9, 28, and 42 d; response to SRBC, Phaseolus vulgaris agglutinin-P, and Escherichia coli administered at 28 d of age; and response to a cold stress on d 5 posthatch. Differences among genetic lines were evident with growth greater for poults from the sire than from the dam line. Performance of poults from older dams was generally superior to that of poults from younger dams. The higher level of vitamin E resulted in a greater than 7-fold increase in blood plasma vitamin E and reduced mortality. There were interactions among the main effects in which the fitness of poults from younger dams was enhanced by the higher level of vitamin E and the effect of breeder age differed among genetic lines.

Age Factors↗
PubMed2006

Effects of dietary vitamin E and fat supplementation on pork quality.

The effects of dietary vitamin E (VE, alpha-tocopherol acetate) and fat supplementation on growth and carcass quality characteristics, oxidative stability of fresh and cooked pork patty in storage, fatty acid profiles of muscle and adipose tissue, and VE concentrations of plasma, muscle, and adipose tissue were studied. Six hundred pigs were allocated to 1 of 6 diets and fed for 63 d in a 3 x 2 factorial design. The dietary treatments included 3 fat levels (normal corn, high oil corn, high oil corn plus added beef tallow) and 2 levels of VE supplementation (40 IU/kg, normal VE supplementation; and 200 IU/kg, high VE supplementation). At 113 kg of BW, 54 pigs were slaughtered as a subsample to evaluate dietary effects on pork quality. Growth performance and meat quality characteristics did not differ (P > 0.05) among treatment groups. The high level of VE supplementation had a beneficial effect on the oxidative stability of pork as indicated by thiobarbituric acid reactive substance (TBARS) values. Lean tissue had lower (P < 0.05) TBARS in the group fed the high VE than in those fed the normal VE level. The TBARS values differed among storage periods (0 to 6 d) and also between fresh and cooked ground ham. Fat type did not significantly affect total saturated and unsaturated fatty acids proportions in the neutral and polar fraction of muscle. Adding VE acetate led to greater (P < 0.05) monounsaturated and total unsaturated fatty acid proportions in neutral lipids of muscle and adipose tissues. Increasing dietary levels of VE acetate increased the concentration of VE in plasma and muscle. These results indicate that dietary VE acetate supplementation increased (P < 0.05) lipid stability and the VE concentration of muscle.

Animal Feed↗
PubMed2006

Effect of dietary vitamin E supplementation and feeding period on pork quality.

Feeding increased levels of dietary vitamin E can inhibit lipid oxidation. The aim of this study was to investigate the effect of levels of dietary alpha-tocopherol acetate (VE) and feeding duration on meat quality and lipid oxidation. Eighty-one pigs were allocated to 1 of 3 diets containing 40, 200, or 400 IU of VE/kg of feed, and each diet group was divided into 3 feeding periods (3, 6, or 9 wk). Carcass characteristics and meat quality were evaluated. Oxidative stability of fresh and cooked pork patties and pork chops was determined after chilled or frozen storage. Increasing dietary concentrations of VE did not affect any growth performance parameter. Drip loss, however, decreased (P < 0.05) with increased dietary VE levels. Moreover, an increased duration of VE feeding improved (P < 0.05) pH and drip loss. Less lipid oxidation (P < 0.05) was detected in fresh ground pork from pigs fed greater concentrations of VE after 4 d of storage. A greater (P < 0.05) resistance to oxidation in cooked ground pork was observed in pigs fed 200 or 400 IU of VE/kg at 2 and 6 d of storage. Fresh and cooked pork patty oxidation decreased (P < 0.05) linearly as feeding duration increased from 3 to 9 wk. After 6 mo of freezer storage, lipid oxidation of pork chops from pigs fed 200 or 400 IU of VE/kg was lower (P < 0.05) than for pigs fed 40 IU of VE/kg. Likewise, lipid oxidation of pork chops of pigs fed VE for an extended period of time (6 wk) was lower (P < 0.05) after 9 mo of storage. Fatty acid profiles of neutral lipid fraction of the LM became more unsaturated (P < 0.05) with added VE to the feed. These results indicate an increased intake of dietary VE concentration, and prolonged feeding of VE can improve drip loss and reduce lipid oxidation in ground pork and pork chops. This study suggests that supplementation with 200 IU of VE/kg of feed for 6 wk before market is beneficial in improving lipid stability and pork quality.

Animal Feed↗
PubMed2005

Child Health Assessment at School Entry (CHASE) project: evaluation in 10 London primary schools.

AIMS: To assess the feasibility of implementing the Child Health Assessment at School Entry (CHASE) questionnaire, developed to capture the multiple dimensions of the health of children in their first year at school, and to evaluate data quality, reliability and validity. METHODS: Parents of 278 year-1 children, from 10 primary schools in two London boroughs, received a parent questionnaire and school nurses completed a separate questionnaire from health and education records for children whose parents consented. Additional data on free school meal eligibility and ethnicity were obtained from the two Local Education Authorities. The parent questionnaire included the Strengths and Difficulties Questionnaire (SDQ) and four dimensions of the Child Health Questionnaire Parent Form-28 (CHQ-PF28). RESULTS: Response rate was 61%. The association between school free school meals eligibility and response rate in each school approached significance (r = -0.62, P = 0.05). Data completeness of the parent questionnaire was high (mean 98%). Data completeness of the school nurse questionnaire was more variable (mean 82%). Cronbach's Alpha was greater than 0.6 for four of the five SDQ scales and greater than 0.7 for the two CHQ-PF28 multi-item scales. Relative to parents with qualifications, parents with no qualifications rated their children as having significantly more conduct problems, peer problems, and overall mental health problems (P < 0.01) as assessed by the SDQ, and significantly lower global health (P < 0.01) as assessed by the CHQ-PF28. Children with special educational needs and children with long-standing illness or disability were rated as having significantly lower global health (P < 0.05) than children without these. Sample tables of inter-school and inter-borough comparison of key findings demonstrate considerable differences in physical and mental health status. DISCUSSION: The questionnaire was acceptable to parents and school nurses, and feasible to implement within existing school resources. Initial tests of internal reliability and validity are satisfactory. These data have the potential to inform interventions and service provision at school and borough level, and public health trends over time.

Accidents↗
PubMed2005

Development of a questionnaire to collect public health data for school entrants in London: Child Health Assessment at School Entry (CHASE) project.

BACKGROUND: To develop a multiprofessional consensus about the relative contributions of the components of children's health and well-being and to develop a questionnaire that can be used to assess these in London's children. METHODS: Semi-structured interviews with health, education and social services professionals were used to identify areas to include in the questionnaire. These ideas were used as the basis for a wider Delphi consultation, with 79 experts in the area of child health. Round 1 of the Delphi asked panelists to rate 54 items as to whether they should be included in the questionnaire or not. Responses were divided into four categories: item to be included measurement method agreed, item to be included measurement method not agreed, no consensus, or excluded. In round 2, consensus was sought for the categories where there was none following round 1. RESULTS: Themes identified by the interviews were: economic factors, ethnicity, environment, nutrition, hygiene and physical activity, growth, suffers from chronic/serious illness, development, disability and learning, accidents and hospital attendances, self-regulation, psychological well-being, significant life events. After Delphi round 1, items included, where quality measurement method was agreed, were: deprivation index (from postcode), child's ethnicity, temporary accommodation, care status, registered with general practitioner, dental visits, height, weight, special educational needs status, baseline educational assessment result, immunization status, visual and hearing function. Following round 2, items relating to chronic illness, mental health, physical functioning, general health, self-esteem, family cohesion and accident status were agreed for inclusion with a measurement method also agreed. The questionnaire was acceptable to parents. CONCLUSION: The validity, reliability and feasibility of this questionnaire must now be examined. This data set, if collected across London, would substantially increase the public health data available and allow trends in health to be monitored.

Child↗
PubMed2002

Optically stimulated luminescence signals of polymineral fine grains in the JSC Mars-1 soil simulant sample.

The results of various experiments which characterise the optically stimulated luminescence (OSL) signals from polymineral fine grains of a Martian soil simulant sample (JSC Mars-1) are presented. The blue-green stimulated luminescence signal has greater thermal stability than the infrared stimulated luminescence signal for pre-heat temperatures between 250 degrees C and 400 degrees C. Fading tests over a 2 month storage period at 20 degrees C indicate that in some aliquots of JSC Mars-1 both the blue-green stimulated luminescence and the infrared stimulated luminescence signals fade by as much as 50%, whereas in others there is no evidence of significant fading. Dose recovery experiments demonstrate that equivalent dose (measured/given) ratio varies from aliquot to aliquot, and the underestimation in dose is less than 5% for at least one aliquot, for both the infrared and blue-green stimulated luminescence signals.

Luminescent Measurements↗
PubMed2002

Dose and dose-rate dependence of optically stimulated signals in quartz: theoretical simulations.

In a recent paper Bailey proposed a general model to describe many optically stimulated luminescence (OSL) and thermoluminescence properties of natural quartz. This model consists of five electron trapping centres and four recombination centres: one of the recombination centres is assumed to be radiative and the remaining non-radiative. This paper investigates some additional aspects of the Bailey model. Firstly, the single-aliquot regenerative-dose (SAR) method has been simulated using the model. It is shown that the simulated natural dose (2 Gy) given to the 'sample' in the simulation can be estimated to within approximately 2% using the SAR method. Furthermore, sensitivity-corrected OSL growth curves have been calculated over a dose range of 0 to 2500 Gy. Using the model, it is also demonstrated that the shape of the sensitivity-corrected OSL growth curve is independent of dose rate, for dose rates of 0.001 Gy x s(-1) and 0.1 Gy x s(-1), over a dose range of 0-500 Gy.

Computer Simulation↗
PubMed2001

Mechanics of venom expulsion in Crotalus, with special reference to the role of the fang sheath.

A combination of anatomical and experimental preparations were used to explore the function of the venom delivery system in rattlesnakes (Crotalus). The distal end of the venom duct is compressed near the point where it empties into the venom chamber, a space surrounding the fang defined by the fang sheath. Within the venom chamber, the inner fang membrane lies obliquely over the base of the fang at least partially occluding the entrance orifice. When the fang is retracted the combination of the compressed venom duct and the spatial position of the inner fang membrane serve to inhibit or block venom flow. As the fang is erected beyond approximately 60 degrees (relative to the roof of the mouth) localized compression of the fang sheath decreases the size of the venom chamber, relieves the compressive force from the venom duct, and displaces the inner fang membrane away from the entrance orifice of the fang. Pressure recordings taken at different locations along the venom delivery system demonstrate that the venom gland produces suction during relaxation of the extrinsic glandular musculature. These findings suggest that the venom delivery system of Crotalus is both more flexible and more regulated than previously assumed.

Animals↗
PubMed2001

Measuring later health status of high risk infants: randomised comparison of two simple methods of data collection.

OBJECTIVE: To test two methods of providing low cost information on the later health status of survivors of neonatal intensive care. DESIGN: Cluster randomised comparison. SETTING: Nine hospitals distributed across two UK health regions. Each hospital was randomised to use one of two methods of follow up. PARTICIPANTS: All infants born </=32 weeks' gestation during 1997 in the study hospitals. METHOD: Families were recruited at the time of discharge. In one method of follow up families were asked to complete a questionnaire about their child's health at the age of 2 years (corrected for gestation). In the other method the children's progress was followed by clerks in the local community child health department by using sources of routine information. RESULTS: 236 infants were recruited to each method of follow up. Questionnaires were returned by 214 parents (91%; 95% confidence interval 84% to 97%) and 223 clerks (95%; 86% to 100%). Completed questionnaires were returned by 201 parents (85%; 76% to 94%) and 158 clerks (67%; 43% to 91%). Most parents found the forms easy to complete, but some had trouble understanding the concept of "corrected age" and hence when to return the form. Community clerks often had to rely on information that was out of date and difficult to interpret. CONCLUSION: Neither questionnaires from parents nor routinely collected health data are adequate methods of providing complete follow up data on children who were born preterm and required neonatal intensive care, though both methods show potential.

Community Health Services↗
PubMed2001

Effectiveness of home based support for older people: systematic review and meta-analysis.

OBJECTIVE: To evaluate the effectiveness of home visiting programmes that offer health promotion and preventive care to older people. DESIGN: Systematic review and meta-analysis of 15 studies of home visiting. PARTICIPANTS: older people living at home, including frail older people at risk of adverse outcomes. OUTCOME MEASURES: Mortality, admission to hospital, admission to institutional care, functional status, health status. RESULTS: Home visiting was associated with a significant reduction in mortality. The pooled odds ratio for eight studies that assessed mortality in members of the general elderly population was 0.76 (95% confidence interval 0.64 to 0.89). Five studies of home visiting to frail older people who were at risk of adverse outcomes also showed a significant reduction in mortality (0.72; 0.54 to 0.97). Home visiting was associated with a significant reduction in admissions to long term institutional care in members of the general elderly population (0.65; 0.46 to 0.91). For three studies of home visiting to frail, "at risk" older people, the pooled odds ratio was 0.55 (0.35 to 0.88). Meta-analysis of six studies of home visiting to members of the general elderly population showed no significant reduction in admissions to hospital (odds ratio 0.95; 0.80 to 1.09). Three studies showed no significant effect on health (standardised effect size 0.06; -0.07 to 0.18). Four studies showed no effect on activities of daily living (0.05; -0.07 to 0.17). CONCLUSION: Home visits to older people can reduce mortality and admission to long term institutional care.

Aged↗
PubMed2001

Universal vs. selective services: the case of British health visiting.

AIMS: This paper discusses whether there should be universal or selective provision of health visiting services. The aim is to show the central relevance of the work of the late epidemiologist, Geoffery Rose, to arguments advocating the retention of a universal health visiting service. BACKGROUND: In the United Kingdom (UK), health visiting moved, in the early years of the twentieth century, from being focused on the needs of poor families to becoming a universally provided service. Recent debates about the future of British health visiting have again raised the issue of whether health visiting remains a universal service, or should be targeted only on the most needy. STRUCTURE: Following an exposition of Rose's work, two kinds of problems with which health visitors are concerned, depression and child abuse, are used to illustrate the ways in which Rose's approach can be applied to health visiting. CENTRAL THESIS: Rose argued that the bulk of problems in society arise in the many who are not at especially high risk, rather than in the few who are at high risk. This is because of a very large number of people who are not at especially high risk. Consequently, following Rose, this paper argues that in relation to such problems as depression or child abuse, to target health visiting services only on those at high risk would be to leave untouched a vast burden of health and social problems. In the context of identifying people who are at greatest risk, Rose argued that no screening instrument can ever be sufficiently precise to accurately identify those most likely to suffer problems. In corroboration of Rose's argument, this paper illustrates the pitfalls of health visitors' attempts to screen for families at greatest risk through the use of such instruments as checklists of risk factors. CONCLUSIONS: It is concluded that it is neither possible to screen accurately for those at greatest risk, nor desirable to target services only on those at greatest risk. Therefore, it is advocated that health visiting should remain a universal service. However, it is recognized that within a universally provided service, some clients will require a greater intensity of input than others. In assessing the need for services, it is argued that the professional judgements of health visitors are crucial.

Child↗
PubMed2001

Expanding the search for a linear separability constraint on category learning.

Formal models of categorization make different predictions about the theoretical importance of linear separability. Prior research, most of which has failed to find support for a linear separability constraint on category learning, has been conducted using tasks that involve learning two categories with a small number of members. The present experiment used four categories with three or nine patterns per category that were either linearly separable or not linearly separable. With overall category structure equivalent across category types, the linearly separable categories were found to be easier to learn than the not linearly separable categories. An analysis of individual participants' data showed that there were more participants operating under a linear separability constraint when learning large categories than when learning small ones. Formal modeling showed that an exemplar model could not account for many of these data. These results are taken to support the existence of multiple processes in categorization.

Exploratory Behavior↗
PubMed2000

Functional subdivision of the venom gland musculature and the regulation of venom expulsion in rattlesnakes.

A combination of histology, whole muscle force physiology, glycogen depletion, and venom expulsion analyses using transonic probes to measure venom flow and fluid pressure transducers to measure venom pressure was performed on the m. compressor glandulae and m. pterygoideus glandulae. The m. pterygoideus glandulae has less than one-third the cross-sectional area of the m. compressor glandulae, and produces approximately one-fifth the total twitch and tetanic force; however, in situ surface stimulation of the muscle produces venom flow and pressure levels that are similar to those produced by the m. compressor glandulae. The similarity in venom output following stimulation reflects in part the functional role of the larger m. compressor glandulae in jaw adduction, but also the functional subdivisions within this muscle. The m. compressor glandulae is divided into a series of columnar fascicles that run from the surface of the muscle to the venom gland. The combined results of clearing and staining and glycogen depletion studies suggest that these fascicles may represent functional compartments. Identical stimulations applied to different regions of the m. compressor glandulae result in up to a six-fold difference in venom expulsion. This functional specialization may play a role in the regulation of venom flow during offensive and defensive strikes.

Animals↗