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C Duncan

Publications and source records attributed to C Duncan.

At least 37 records · Page 2Linked to original sources
PubMed2000

Death and deprivation: an exploratory analysis of deaths in the health and lifestyle survey.

An analysis is undertaken of deaths of respondents in the UK- representative Health and Lifestyle Survey. The sample was originally interviewed in 1984/5 and followed initially until May 1997. Using multilevel logistic and Cox-proportional hazards models, the relationships between death and a wide range of social circumstances and behaviours is explored. It is found that place deprivation interacts with individual social class in accounting for variations in mortality. This is the case even when account is taken of personal health-related behaviour. There appears to be some evidence of a threshold relationship such that the differential effects of social class are only found at high-levels of deprivation. No statistically significant interactions are found for social and behavioural variables, for behavioural and place deprivation variables, and for social and place deprivation variables with the exception of social class. The study is deliberately exploratory and a wide range of models have been fitted which will be subject to more rigorous evaluation as the HALS death study proceeds.

Health Behavior↗
PubMed2000

London's burning: recovering other geographies of health.

In the opening to this paper we concern ourselves with the concept of health as it is currently understood in the now reformulated 'geography of health'. We focus on countering the assumption that the desire for health is the main drive behind individual patterns of consumption. To this end, we turn to a more culturally informed analysis which identifies the importance of understanding the complex relations between the body, identity, consumption and risk. To illustrate our ideas and arguments, we draw on current anti-smoking debates, particularly those relating to passive smoking, and what we see as evidence of alternatives to such health-related or 'healthist' rhetoric: the rise of cigar smoking and cigar bars in London, England.

Consumer Behavior↗
PubMed2000

Consumed with worry: 'unsafe' alcohol consumption and self-reported problem drinking in England.

Using data from the 1994 Health Survey for England, logistic multivariate multilevel modelling techniques are used to investigate the simultaneous effect of individual demographic characteristics and socio-structural factors on self-reported problem drinking as revealed by CAGE scores and 'unsafe' levels of alcohol consumption. Whilst the influence of key socio-structural variables is broadly similar for both unsafe alcohol consumption and high CAGE scores, there are notable exceptions when results are examined by tenure group: those in the rented sector are more likely to be problem drinkers as revealed by CAGE, but less likely to consume 'unsafe' amounts of alcohol. Both dimensions of drinking behaviour are influenced by the consumption patterns of others in the household, with both likelihoods increasing as the average consumption of others in the household rises. After taking into account individual compositional variables, the research indicates that there is very little evidence for geographical variation remaining in these two dimensions of drinking behaviour. It is found that the proportion of the population whose drinking behaviour may be classed as (potentially) problematic via the CAGE responses is substantially less than the proportion consuming above recommended 'safe' levels. The research concludes, however, that the two measures are broadly similar in their relationship to social and structural variables. Tenure provides an exception to this conclusion and indicates a continuing need to take account of housing circumstances in developing an understanding of drinking behaviour.

Adolescent↗
PubMed1999

Smoking and deprivation: are there neighbourhood effects?

Debate has centred on whether the character of places plays an independent role in shaping individual smoking behaviour. At the small-area scale, particular attention has focused on whether measures of neighbourhood deprivation predict an individual's smoking status independent of their own personal characteristics. This study applies multilevel modelling techniques to data from the British Health and Lifestyle Survey and ward (local neighbourhood) level deprivation scores based on four variables from the national Census. Results suggest that after taking account of a large range of individual characteristics, both as main effects and interactions, together with complex structures of between-individual variation, measures of neighbourhood deprivation continue to have an independent effect on individual smoking status. In addition, significant between-ward differences in smoking behaviour remain which cannot be explained either by population composition or ward-level deprivation. The study suggests that the character of the local neighbourhood plays a role in shaping smoking behaviour.

Adult↗
PubMed1999

Geographies of health perception in Québec: a multilevel perspective.

Self perceived health is a widely used measure and, in Quebec, it has been shown to vary significantly between geographical areas. In the present study, these geographical variations are examined in a multilevel analysis in order to disentangle compositional (individual characteristics) and contextual (place) effects. The analysis recognizes four levels of variation: individual, household, local and regional. Similar analyses carried out in Britain, have considered only two levels: individual and local. Data come from the 1992-1993 Quebec Health and Social Survey, a general household survey using a stratified two-stage sampling design. Health perception (the response variable) is considered with a set of individual predictor characteristics reflecting gender, lifestyle, socio-economic conditions, marital status and social support. Results show the existence of significant local area variations in health perception after having allowed for individual characteristics and variations at the household level. At the regional level, however, no systematic and significant variations remain although some individual regions are found to have a significant impact on health perception.

Adult↗
PubMed1998

Context, composition and heterogeneity: using multilevel models in health research.

This paper considers the use of multilevel models in health research. Attention focuses on the structure and potential of such models and particular consideration is given to their use in elucidating the importance of contextual effects in relation to individual level social and demographic factors in understanding health outcomes, health-related behaviour and health service performance. Four graphical typologies are used to outline the questions that multilevel models can address and the paper illustrates their potential by drawing on published examples in a number of different research areas.

Analysis of Variance↗
PubMed1997

Protection against oral and gastrointestinal diseases: importance of dietary nitrate intake, oral nitrate reduction and enterosalivary nitrate circulation.

Over the last 20 years, dietary nitrate has been implicated in the formation of methemoglobin and carcinogenic nitrosamines in humans. This has led to restrictions of nitrate and nitrite levels in food and drinking water. However, there is no epidemiological evidence for an increased risk of gastric and intestinal cancer in population groups with high dietary vegetable or nitrate intake. A reevaluation of our currently very negative perception of dietary nitrates comes from recent research into the metabolism and enterosalivary circulation of nitrate in mammals. These studies showed that nitrate is converted to nitrite in the oral cavity that then "fuels" an important mammalian resistance mechanism against infectious diseases. Moreover, there is now evidence that the conversion of nitrate into oxides of nitrogen prevents the formation carcinogenic nitrosamines.

Animals↗
PubMed1997

Nitrate-reducing bacteria on rat tongues.

Nitrite-producing bacteria (NPB) were isolated from tongues of laboratory rats. The most commonly found nitrite-producing organism was Staphylococcus sciuri, followed by Staphylococcus intermedius, Pasteurella spp., and finally Streptococcus spp. Both morphometric quantification of bacteria on tongue sections and enumeration of culturable bacteria (CFU) showed an increase in the density of bacteria towards the posterior tongue. Up to 65% of bacteria were located in the deep clefts on the posterior tongue. The proportion of culturable NPB in the total culturable microbial population increased from 6% (10(5) CFU cm-2) on the anterior tongue to 65% (10(7) CFU cm-2) on the posterior tongue. Different species compositions of NPB were found on different tongue sections with S. intermedius populations decreasing and S. sciuri and Pasteurella populations increasing towards the posterior tongue. Nitrite production was sensitive to oxygen, and significant nitrite production was only detected on the posterior tongue where the majority of bacteria are situated in deep clefts in the tongue surface. This study suggests the importance of bacteria in nitrite production, from nitrate, on the tongue. Nitrite produced on the tongue may subsequently form nitric oxide in the acidic environment of the stomach. Because of the antimicrobial properties of nitric oxide, a key role for nitrate-reducing tongue bacteria in host animal defense against food-borne pathogens in proposed.

Animals↗
PubMed1996

Prenatal diagnosis and carrier screening for fragile X by PCR.

During the past three years, we have conducted fragile X DNA studies for carrier screening and prenatal diagnosis using a previously described PCR protocol that accurately resolves normal FMR1 alleles and premutations and detects most full mutations [Brown et al., JAMA 270:1569-1575, 1996]. A total of 344 pregnant women with a family history of mental retardation of unknown cause were screened and 6 fragile X carriers were identified: two had full mutations, and four had premutations. The mentally retarded relatives of two other women were found to be fragile X positive although the women themselves were not carriers. In all, 6 carriers and 8 fragile X families were identified by this screening. We have also screened 40 pregnant women who were members of previously identified fragile X families, but whose carrier status was unknown. Ten were found to be carriers and were offered prenatal diagnosis. Prospective prenatal testing of 84 carrier women correctly detected 31 fetal samples (19 females, 12 males) with full mutations and 6 with premutations (2 females, 4 males). No false positives but one false negative occurred early on due to undetected maternal cell contamination. In addition, screening of 806 males with developmental delays of unknown cause gave positive results in 33 (4.1%). Potential problems and pitfalls of direct DNA testing are discussed. Because of the proven success of fragile X screening with direct molecular analysis, screening of all undiagnosed individuals with mental retardation and at risk pregnant women should now be considered. The identification of fragile X carriers and prenatal diagnosis of their pregnancies should significantly reduce the prevalence of this syndrome.

Amniocentesis↗
PubMed1996

Inhibition of yeast-to-mycelium conversion of Candida albicans by conjugated styryl ketones.

Candida albicans is a dimorphic pathogenic yeast capable of producing alternate morphological forms (yeast or mycelium) in response to environmental changes. The dimorphism of C. albicans plays an important role in the pathophysiology of this organism. The intracellular level of glutathione, which helps to maintain the oxidation-reduction potential of the cell, is decreased significantly during the yeast-to-mycelium conversion implicating the possible involvement of thiols in the yeast-to-mycelium transition. To evaluate the possible participation of sulphydryl group(s) containing component(s) in the yeast-to-mycelium transition of C. albicans, we examined the effect of a group of newly synthesized thiol-alkylators on the production of germ tubes from yeast cells. Several conjugated styryl ketones which are thiol-alkylators, and p-chloromercuriphenylsulphonate (a known nonpenetrating thiol-blocker) inhibited the yeast-to-mycelium conversion of C. albicans. The thiol-alkylators at 20 microM failed to inhibit four key enzymes (gamma-glutamyltranspeptidase, glutathione reductase, glutathione S-transferase and glutathione peroxidase) involved in glutathione utilization indicating that the inhibition of yeast-to-mycelium conversion is not mediated by the inhibition of glutathione metabolic enzymes. Moreover, these results suggest that a key thiol-blocker sensitive component(s) containing a critical sulphydryl group(s) is involved in the yeast-to-mycelium transition of C. albicans.

4-Chloromercuribenzenesulfonate↗
PubMed1996

Health-related behaviour in context: a multilevel modelling approach.

Recent attempts to place individual health-related behaviour in context have been judged largely unsuccessful. This paper examines how this situation might be improved and is especially concerned with the role of quantitative methodologies. It is argued that, whilst recent developments in social theory help provide important theoretical guidelines, they can only be implemented with difficulty in empirical health-related behaviour research if traditional quantitative methodologies are used. It is suggested that the best way to implement social theory within a quantitative framework is to apply the newly developed technique of multilevel modelling. This paper offers an overview of the multilevel approach and outlines its significance for health-related behaviour research. In addition, it details a number of ways in which the multilevel framework can be extended so as to achieve further improvements in the conceptualization of health-related behaviour. To illustrate the value of the technique, the paper finishes by considering one of these extensions in detail and applying it to data recording smoking behaviour in the United Kingdom.

Adolescent↗
PubMed1996

Mood management and nicotine gum in smoking treatment: a therapeutic contact and placebo-controlled study.

Earlier research indicated that a 10-session mood management (MM) intervention was more effective than a 5-session standard intervention for smokers with a history of major depressive disorder (MDD). In a 2 x 2 factorial design, the present study compared MM intervention to a contact-equivalent health education intervention (HE) and 2 mg to 0 mg of nicotine gum for smokers with a history of MDD. Participants were 201 smokers, 22% with a history of MDD. Contrary to the earlier findings, the MM and HE interventions produced similar abstinence rates: 2 mg gum was no more effective than placebo. History-positive participants had a greater increase in mood disturbance after the quit attempt. Independent of depression diagnosis, increases in negative mood immediately after quitting predicted smoking. No treatment differences were found in trends over time for measures of mood, withdrawal symptoms, pleasant activities and events, self-efficacy, and optimism and pessimism. History-positive smokers may be best treated by interventions providing additional support and contact, independent of therapeutic content.

Adult↗
PubMed1996

Antimicrobial effect of acidified nitrite on gut pathogens: importance of dietary nitrate in host defense.

Dietary intake of nitrate generates salivary nitrite, which is acidified in the stomach, leading to a number of reactive intermediates of nitrogen, among which are the potentially carcinogenic N-nitrosamines. Acidified nitrite, however, also has antimicrobial activity which coincides with the formation of nitric oxide. The present study examines the antimicrobial effect in vitro of acidified nitrite on Salmonella enteritidis, Salmonella typhimurium, Yersinia enterocolitica, Shigella sonnei, and Escherichia coli O157. First-order regression plots showed a linear inverse relationship of log-transformed proton and nitrite concentrations with MICs and MBCs after 30 min, 2 h, and 24 h of exposure (P < 0.001 for all antibacterial activities). Susceptibility to the acidified nitrate solutions ranked as follows: Y. enterocolitica > S. enteritidis > S. typhimurium = Shigella sonnei > E. coli O157 (P < 0.05). Addition of SCN-, but not that of CI-, increased the antibacterial activity (paired t testing, P < 0.001). Generation of salivary nitrite from dietary nitrate may provide significant protection against gut pathogens in humans.

Diet↗