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Biomedical subjects

C E Dunn

Publications and source records attributed to C E Dunn.

12 recordsLinked to original sources
PubMed2001

Analysing spatially referenced public health data: a comparison of three methodological approaches.

In the analysis of spatially referenced public health data, members of different disciplinary groups (geographers, epidemiologists and statisticians) tend to select different methodological approaches, usually those with which they are already familiar. This paper compares three such approaches in terms of their relative value and results. A single public health dataset, derived from a community survey, is analysed by using 'traditional' epidemiological methods, GIS and point pattern analysis. Since they adopt different 'models' for addressing the same research question, the three approaches produce some variation in the results for specific health-related variables. Taken overall, however, the results complement, rather than contradict or duplicate each other.

Adult↗
PubMed2000

Is it feasible to construct a community profile of exposure to industrial air pollution?

OBJECTIVE: An epidemiological investigation to assess the validity of residential proximity to industry as a measure of community exposure. METHODS: 19 Housing estates in Teesside (population 1991: 77 330) in north east England were grouped into zones: A=near; B=intermediate; C=further from industry. With residential proximity of socioeconomically matched populations as a starting point a historical land use survey, historical air quality reports, air quality monitoring, dispersion modelling data, and questionnaire data, were examined. RESULTS: The populations in zones A, B, and C were similar for socioeconomic indicators and smoking history. Areas currently closest to industry had also been closest for most of the 20th century. Historical reports highlighted the influence of industrial emissions to local air quality, but it was difficult to follow spatial pollution patterns over time. Whereas contemporary NO(x) and benzene concentrations showed no geographical variation, dispersion modelling of emissions (116 industrial stacks, traffic, and domestic sources) showed a gradient associated with industry. The presumed exposure gradient of areas by proximity to industry (A>B>C) was evident for all of zone A and most of zones B and C. CONCLUSIONS: It was feasible to assemble a picture of community exposure by integration of measurements from different sources. Proximity of residence was a reasonable surrogate for complex community exposure.

Air Pollutants↗
PubMed1998

Cultural differences on three measures of dissociation in a substance abuse population.

Scores on three measures of dissociation were compared between 48 African American and 48 Caucasian men being treated for substance abuse at a VA Medical Center. The three assessment instruments included the Dissociative Experience Scale, the Questionnaire of Experiences of Dissociation, and the North Carolina Index of Dissociation. Groups were matched with respect to age, education, marital status, number of previous treatments, IQ, employment status, history of childhood abuse, and psychological discomfort. In each case, the African-American group scored higher, with statistical significance being achieved on two of the three instruments. Potential implications of these findings were discussed and future research was suggested.

Adult↗
PubMed1998

Does living near a constellation of petrochemical, steel, and other industries impair health?

OBJECTIVES: To investigate concern that local industrial air pollution in Teesside, England, was causing poor health, several areas there were compared with parts of the City of Sunderland. METHODS: Populations in similar social and economic circumstances but varying in their proximity to major industries were compared. Study populations lived in 27 housing estates in Teesside and Sunderland, north east England, with some data from subsets of estates. The estates were aggregated into zones (designated as A, B, and C in Teesside where A is closest to and C furthest from industry, and S in Sunderland). Zone S provided a reference area. The hypothesis was that a health gradient both within Teesside (A > B > C) and between Teesside and Sunderland (ABC > S) would indicate a possible health effect of local industrial air pollution. Data presented were: mortality (1981-91) from 27 housing estates; population self completion questionnaire survey data (1993, 9115 subjects) from 15 housing estates; and general practitioner (GP) consultation data (1989-94) from 2201 subjects in 12 Teesside estates. RESULTS: The populations in the four zones were comparable for indicators including smoking habits, residential histories, and unemployment. All cause and cause specific mortalities were high compared with England and Wales. Mortality in all Teesside zones (ABC) combined was mostly higher than in zone S. In people aged 0-64, lung cancer and respiratory disease showed gradients with highest mortality in areas closest to industry (A > B > C and ABC > S). The association was clearest for lung cancer in women (0-64 years old, trend across zones ABC, p = 0.07, directly standardised rate ratio relative to zone S was 169 (95% confidence interval (95% CI) 116-122)). There were no important, consistent gradients in the hypothesised direction between zones in consultation rates in general practice, and self reported respiratory and nonrespiratory health including asthma. CONCLUSIONS: There was no clear evidence that living close to industry was associated with morbidity, including asthma, or for most measures of mortality. For lung cancer in women the gradients indicated a health effect of local industrial air pollution. In the age group 0-64 observed gradients in lung cancer in men and mortality from respiratory disease in men and women were consistent with the study hypothesis, although not significant. The reasons for the different patterns at different ages, and between men and women, remain a puzzle.

Adolescent↗
PubMed1995

Asthma and factory emissions in northern England: addressing public concern by combining geographical and epidemiological methods.

STUDY OBJECTIVE: The prevalence of asthma was assessed to investigate respiratory health effects of airborne emissions from a factory. A geographical information system allowed flexible definition of study areas in terms of their size, distance, and location in relation to the factory. The value of the approach for this type of investigation is focussed on. SETTING: The factory is located in the south western part of a small market town in County Durham. MEASUREMENTS AND MAIN RESULTS: A total of 1573 asthma cases were identified from general practitioner computerised repeat prescribing systems. Population denominators were defined from family health services authority patient registers. The area within 1 km and immediately to the north east of the factory had an age and sex standardised asthma prevalence 24% (confidence interval 4, 44%) in excess of the expected rate (p = 0.01). The increased prevalence was confined to middle aged and elderly adults living in the area between 0.5 and 1 km to the north east of the factory. CONCLUSIONS: The value of combining the skills of geographers and epidemiologists in addressing public health issues is shown, particularly through the use of geographical information systems which proved powerful and effective.

Adolescent↗
PubMed1994

Cytokines affect ion transport in primary cultured thick ascending limb of Henle's loop cells.

Tumor necrosis factor-alpha (TNF) and interleukin-1 (IL-1) affect epithelial cell ion transport. However, the site of action along the nephron has not been elucidated fully for these cytokines. Thus, the effect of TNF and IL-1 on the ion transport function of primary cultured medullary thick ascending limb of Henle's loop (mTALH) cells was determined by measuring rubidium (86Rb) uptake. TNF, IL-1, and lipopolysaccharide (LPS), a known activator of cytokine production, inhibited 86Rb uptake by cultured mTALH cells after a 24-h incubation period but had no effect when incubated with the cells for 1 or 4 h. Furthermore, mTALH cells produced biologically active TNF after stimulation with LPS for 24 h, and the LPS-induced inhibition of 86Rb uptake was abolished in the presence of an anti-TNF antibody, suggesting that TNF produced by the mTALH cells acted in an autocrine manner to inhibit 86Rb uptake. The effects of LPS on 86Rb uptake also were inhibited by the cyclooxygenase inhibitor, indomethacin. As TNF increased prostaglandin E2 synthesis by cultured mTALH cells and as prostaglandin E2 also inhibited 86Rb uptake, LPS presumably inhibited 86Rb uptake by inducing a TNF-mediated increase in prostaglandin synthesis. These data demonstrate that a prostanoid produced by mTALH cells mediates the inhibitory effect of LPS and TNF on 86Rb uptake and imply that endogenous TNF inhibits ion fluxes in the mTALH via a prostaglandin-dependent mechanism.

Animals↗
PubMed1991

Structural identification of cytochrome P450-dependent arachidonate metabolites formed by rabbit medullary thick ascending limb cells.

The medullary thick ascending limb of Henle's loop (mTALH) contributes importantly to the regulation of extracellular fluid volume and composition and metabolizes arachidonic acid (AA) chiefly by a cytochrome P450 monooxygenase pathway. Rabbit mTALH cells, when incubated with radiolabeled [14C]AA, form products that segregate into two peaks designated P1 and P2 based on their reverse-phase high pressure liquid chromatography retention times. We have now definitively identified their chemical structures. mTALH cells, isolated from the rabbit outer medulla, were homogenized and incubated with [14C]AA in the presence of NADPH. The AA metabolites in P1 and P2 were identified by gas chromatographic-mass spectrometric methods, including fast atom bombardment, negative ion electron capture, and electron ionization. All mass spectrometric data, the lack of UV chromophores, and comparisons with authentic standards were consistent with P1 containing two principal components: 19-hydroxy-5,8,11,14 eicosatetraenoic acid (19-HETE) and 20 - hydroxy - 5,8,11,14 - eicosatetraenoic acid (20-HETE), P2 contained primarily 1,20-eicosa-5,8,11,14-tetraenedioic acid (20-COOH-AA). The biological properties of P1 and P2 were compared with those of the authentic standards of 19- and 20-HETE and 20-COOH-AA. P1 dose dependently relaxed precontracted mesenteric arterial rings, as did authentic (19S)- and (19R)-HETE, whereas 20-HETE relaxed at lower and contracted at higher concentrations. As P1 contained a mixture of 19- and 20-HETE, each of these AA metabolites presumably contributed to the vascular relaxation produced by P1. Neither P2 nor 20-COOH-AA exhibited vasoactivity, but each demonstrated a similar potency in inhibiting rabbit medullary Na(+)-K(+)-ATPase activity. As previously reported, P2 was a more potent inhibitor of Na(+)-K(+)-ATPase than P1. The lesser inhibitory activity of P1 presumably reflects the presence of similar amounts of 19-HETE, the least active metabolite, and 20-HETE, which resembles 20-COOH-AA in its capacity to inhibit Na(+)-K(+)-ATPase. Thus, the biological activity of the less polar peak, P1, can be accounted for by 19- and 20-HETE, and that of P2, by 20-COOH-AA.

Animals↗
PubMed1988

The effect of hyperemia on spinal cord function after temporary thoracic aortic occlusion.

Nineteen mongrel dogs had 30 minutes of thoracic aortic occlusion to determine the effects that blockade of the renin-angiotensin system may have on preserving spinal cord blood flow and function during a period of temporary spinal cord ischemia. Cross-clamping of the thoracic aorta causes renal ischemia and activates the renin-angiotensin system with resulting increased production of angiotensin II. Angiotensin II is a potent peripheral constrictor and elevated levels may constrict collateral spinal cord circulation. At the time of aortic cross-clamping, 10 dogs received 100 mg/kg of MK422 (intravenous enalapril maleate), a converting enzyme inhibitor, and nine animals served as controls. The blockade of the renin-angiotensin system had no preserving effects on spinal cord flow as measured by microspheres and on spinal cord function as graded with the Tarlov scale. However, the paraplegic animals all had significantly increased lower thoracic and lumbar spinal cord flows 30 minutes after clamp release when compared with those animals that remained neurologically intact. In conclusion, marked hyperemia occurring after a period of hypoperfusion may lead to spinal cord edema and compartment syndrome with resulting paraplegia.

Animals↗
PubMedDate not supplied

Trauma symptoms in substance abusers with and without histories of childhood abuse.

This study was designed to provide a prevalence rate of childhood abuse in patients being treated for alcohol and other drug problems, and to compare the extent of trauma symptoms that were present in substance abusers with and without childhood histories of physical, sexual, and emotional abuse. One hundred male veterans completed a standard test battery that included the Trauma Symptom Checklist and the Dissociative Experiences Scale. Clinical information pertaining to history of childhood abuse was obtained from the subjects' medical charts. Results demonstrated that 34% of the sample reported a history of childhood abuse. Although this group did achieve higher mean scores on all the scales, in comparison to the nonabused group, statistical significance was absent. Implications of these findings are discussed and future research is suggested.

Anxiety Disorders↗
PubMedDate not supplied

Enzyme immunoassay for antibodies to Epstein-Barr virus nuclear antigen.

An enzyme immunoassay that detects IgM and IgG antibodies to the nuclear antigen of Epstein-Barr virus (EBV) is evaluated. The EIA was compared with a rapid monoscreen (Immunoscan-IM) and an indirect fluorescent antibody procedure to determine the correlation of the new test with the current methodology. Among 73 patients tested for heterophilic antibody, 36 were positive; 25 of these had IgM antibodies to nuclear antigen. The sensitivity of the EIA compared to the mono screen was 69.4% and specificity was 97.3%. In comparison with fluorescence assays for IgG to the nuclear antigen, 94 patients were tested with 84 showing positivity by the fluorescent method. Among these, 80 were positive by EIA yielding a sensitivity and specificity of 95.2% and 90.0%, respectively. The EIA does not appear sensitive enough for replacement of the monoscreen but was a sensitive, cost-effective alternative to the indirect fluorescent antibody test.

Adolescent↗