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Biomedical subjects

K Wilson

Publications and source records attributed to K Wilson.

At least 37 records · Page 2Linked to original sources
PubMed2001

A microsatellite polymorphism in the gamma interferon gene is associated with resistance to gastrointestinal nematodes in a naturally-parasitized population of Soay sheep.

Free-living Soay sheep (Ovis aries) on the island of Hirta, St Kilda, Scotland, are naturally parasitized by gastrointestinal nematodes, predominantly Teladorsagia circumcincta. In this paper we show that reduced faecal egg counts (FEC) are associated with an allele at a microsatellite locus located in the first intron of the interferon gamma gene (o(IFN)-gamma) in Soay sheep lambs and yearlings, measured at approximately 4 and 16 months of age, respectively. The same allele was also associated with increased T. circumcincta-specific antibody (IgA) in lambs, but not associated significantly in yearlings. Flanking control markers failed to show a significant association with either FEC or IgA. These results suggest that a polymorphic gene conferring increased resistance to gastrointestinal nematode parasites is located at or near the interferon gamma gene, and support previous reports which have mapped a quantitative trait locus (QTL) for resistance to this region in domestic sheep. Our data are consistent with the idea that a functional polymorphism leading to reduced expression or efficacy of (IFN)-gamma could enhance the immune response to gastrointestinal nematodes by favouring the activity of the Th2 cell subset and antibody associated immune mechanisms.

Animals↗
PubMed2001

Degradation of mannan I and II crystals by fungal endo-beta-1,4-mannanases and a beta-1,4-mannosidase studied with transmission electron microscopy.

We have used the endo-beta-1,4-mannanase from Trichoderma reesei (Tr Man5A), the endo-beta-1,4-mannanase from Aspergillus niger (An Man5A) and the exo-beta-1,4-mannosidase from A. niger (An Mnd2A) to follow the enzymatic degradation of mannan I and II crystals. The degradation process was studied by transmission electron microscopy and also followed by analysis of the released soluble reducing sugars. The mannan crystals were degraded by the endo-beta-1,4-mannanases and to a lesser extent by the exo-beta-1,4-mannosidase. The observed hydrolysis pattern on mannan I crystals is fully consistent with the current view of the molecular structure of these crystals. The molecular organization of the mannan chains in mannan II crystals is less clear and the digestion results give some further information about the ultrastructure of mannan II. In addition, insight is provided into the mode of the enzymatic attack on the crystals of mannan I and mannan II.

Aspergillus niger↗
PubMed2001

Comparison of brachial artery pressure and derived central pressure in the measurement of abdominal aortic aneurysm distensibility.

OBJECTIVE: AAA distensibility (Ep, beta) may predict growth and risk of rupture. However, distensibility measurements based on brachial rather than central pressure may be inaccurate. Our aim was to compare AAA distensibility using non-invasive brachial and derived central aortic pressure. DESIGN: brachial and central pressures were measured prospectively by automated sphygmomanometry (Omron) and pulse wave analysis (SphygmoCor) respectively. AAA distensibility was calculated using brachial (Ep(b), beta(b)) and central (Ep(c), beta(c)) pressures by ultrasonic echo-tracking (Diamove). Twenty-eight patients (18 males) were selected on a first come basis from a larger study of AAA patients. There were no exclusion criteria, so 54% had cardiac dysfunction (MI, angina) and 14% were hypertensive (BP >140/90 mmHg). RESULTS: median (IQR) age was 74 (70-77) years, median AAA (IQR) diameter was 44 (40-51) mm. Central and brachial systolic pressures were significantly different, [140 (121-153) vs 144 (130-164) mmHg respectively, p < or =0.01]. Central and brachial diastolic pressures were not significantly different [76 (72-86) vs 76 (71-86) mmHg respectively, p=0.5]. Ep(c)(3.0, [2.2-4.9]) and beta(c)(22.2 [15.5-33.2]) were significantly lower than Ep(b)(3.6, [2.4-5.1] 10(5)Nm(-2)) and beta(b)(24.7 [17.1-33.0] a.u., all p < 0.001. Brachial and central derived distensibility remained significantly different after adjusting for age and diameter (p<0.001). CONCLUSION: the use of brachial pressure leads to a small, systematic overestimate of Ep (18%) and beta (11%) independent of age and AAA diameter. This systematic error will not bias follow-up of changes in distensibility.

Aged↗
PubMed2001

Racial and ethnic disparities in infant mortality: risk in social context.

This article presents the multifaceted efforts of Syracuse Healthy Start, a federally funded initiative of the Onondaga County Health Department and over 20 partnering agencies to reduce racial and ethnic disparities in infant mortality. The analyses presented in this article demonstrate that many women--Caucasian, African American, and Hispanic--have serious risks for low birth weight and infant death. In many cases, multiple, simultaneous risks complicate a pregnant woman's situation and in other cases the longitudinal cumulative risks impact health across generations. Infant mortality decreased overall, and for both Caucasian and African American infants during the first 3 years of the project.

Black or African American↗
PubMed2001

Positive genetic correlation between parasite resistance and body size in a free-living ungulate population.

Parasite resistance and body size are subject to directional natural selection in a population of feral Soay sheep (Ovis aries) on the island of St. Kilda, Scotland. Classical evolutionary theory predicts that directional selection should erode additive genetic variation and favor the maintenance of alleles that have negative pleiotropic effects on other traits associated with fitness. Contrary to these predictions, in this study we show that there is considerable additive genetic variation for both parasite resistance, measured as fecal egg count (FEC), and body size, measured as weight and hindleg length, and that there are positive genetic correlations between parasite resistance and body size in both sexes. Body size traits had higher heritabilities than parasite resistance. This was not due to low levels of additive genetic variation for parasite resistance, but was a consequence of high levels of residual variance in FEC. Measured as coefficients of variation, levels of additive genetic variation for FEC were actually higher than for weight or hindleg length. High levels of additive genetic variation for parasite resistance may be maintained by a number of mechanisms including high mutational input, balancing selection, antagonistic pleiotropy, and host-parasite coevolution. The positive genetic correlation between parasite resistance and body size, a trait also subject to sexual selection in males, suggests that parasite resistance and growth are not traded off in Soay sheep, but rather that genetically resistant individuals also experience superior growth.

Alleles↗
PubMed2001

Macrophage-specific expression of human lipoprotein lipase accelerates atherosclerosis in transgenic apolipoprotein e knockout mice but not in C57BL/6 mice.

Transgenic mice with macrophage-specific expression of human (hu) lipoprotein lipase (LPL) were generated to determine the contribution of macrophage LPL to atherogenesis. Macrophage specificity was accomplished with the scavenger receptor A promoter. Complete characterization demonstrated that macrophages from these mice expressed huLPL mRNA and secreted enzymatically active huLPL protein. Expression of huLPL was macrophage specific, because total RNA isolated from heart, thymus, lung, liver, muscle, and adipose tissues was devoid of huLPL mRNA. Macrophage-specific expression of huLPL did not exacerbate lesions in aortas of C57BL/6 mice even after 32 weeks on an atherosclerotic diet. However, when expressed in apolipoprotein E knockout background, the extent of occlusion in the aortic sinus region of male huLPL+ mice increased 51% (n=9 to 11, P<0.002) compared with huLPL- mice after they had been fed a Western diet for 8 weeks. The proatherogenic effect of macrophage LPL was confirmed in serial sections of the aorta obtained after mice had been fed a Western diet for 3 weeks. By immunohistochemical analysis, huLPL protein was detected in the lesions of huLPL+ mice but not in huLPL- mice. Our results establish that macrophage LPL accelerates atherosclerosis in male apolipoprotein E knockout mice.

Animals↗
PubMed2001

Pulmonary tumor embolism as a presenting feature of cavoatrial hepatocellular carcinoma.

Pulmonary tumor embolism as a presenting feature of hepatocellular carcinoma is rare. It has been reported only once previously. In that case, other signs and symptoms of liver disease were present. We report the case of a patient with cavoatrial hepatocellular carcinoma presenting with isolated pulmonary tumor embolism, without any clinical or laboratory evidence of liver disease. Hepatocellular carcinoma should be included in the differential diagnosis as a rare cause of pulmonary tumor embolism.

Aged↗
PubMed2001

Testing relationships among determinants of health, health policy, and self-assessed health status in Quebec.

By removing financial barriers, the Canada Health Act (1984) equalized access to health care services in Canada. Yet class, educational, and geographical disparities in individual and population health status persist. Recent health reform policies in Quebec assert that health and well-being are a function of income, educational level, housing conditions, employment, and other socioeconomic factors. They suggest that health policy should encompass social policies that influence individual and community socioeconomic factors which in turn affect health. Against the backdrop of these reforms, this study tests the importance of socioeconomic factors as a determinant of health--while controlling for other known determinants through a logistic regression model--with data from the Santé Quebec health surveys 1987 and 1992-93. The results confirm the importance of economic security as a determinant of individual health. This effect appears to operate through an individual income variable and through the community-level variable of regional unemployment. The importance of the income effect declined between 1987 and 1992-93. This may indicate that an increased focus on the socioeconomic determinants of health has reduced inequalities in health. It may also mean that health inequalities appear inevitable until health care policy merges completely with broader health and social policies. But such integration may well conflict with economic (and political) imperatives of the post-Fordist capitalist system.

Adolescent↗
PubMed2001

Down-regulation of cell adhesion molecules LFA-1 and ICAM-1 after in vitro treatment with the anti-TNF-alpha agent thalidomide.

The tumor necrosis factor-alpha (TNF-alpha) inhibitor thalidomide is known to be a potent modulator of host immunity, a potential treatment for autoimmune disorders such as rheumatoid arthritis (RA) and a treatment for complications of HIV-1 infection. RA is an autoimmune disease of the joints that has been associated with hyperactivity of lymphocytes and other leukocytes, over-expression of pro-inflammatory cytokines (TNF-alpha and IL-1) and chronic debilitating inflammation. Thalidomide may play a role in RA treatment by altering leukocyte function through down-modulation of cell adhesion molecules necessary for leukocyte migration to inflammatory sites. The present study investigates down-regulation of cell adhesion molecules (ICAM-1 and LFA-1) and decreases in cell-cell contacts between human T leukemic (CEM) cells and human umbilical vein endothelial cells (HUVEC) after thalidomide exposure. CEM cells were cultured in RPMI 1640 medium with 0, 10 or 50 microg/ml thalidomide, stained with fluorescent monoclonal antibodies specific to ICAM-1 and LFA-1 and expression was measured with flow cytometry. For cell-cell adhesion measurements, monolayers of HUVEC cultured in Kaign's F-12 medium were incubated with thalidomide treated CEM cells stained with calcein AM. Specific cell adhesion between the two cell types was visualized with fluorescence microscopy. Thalidomide treatment significantly reduced cell adhesion molecule expression in a dose-dependent fashion and inhibited HUVEC/CEM cell adhesion. These data support the hypothesis that thalidomide has modulatory actions on leukocyte functions through expression of cell adhesion molecules.

Cell Adhesion↗
PubMed2000

Risk of acquiring Creutzfeldt-Jakob disease from blood transfusions: systematic review of case-control studies.

OBJECTIVE: To determine the strength of association between history of blood transfusion and development of Creutzfeldt-Jakob disease. DATA SOURCES: English and non-English language articles published from January 1966 to January 1999 were retrieved using a keyword search of Medline and Embase. These were supplemented by handsearching key journals and searching bibliographies of reviews. STUDY SELECTION: Two independent reviewers selected the relevant abstracts and articles. Articles were chosen that reported the results of case-control studies trying to identify rates of prior blood transfusion in patients with Creutzfeldt-Jakob disease and in controls. DATA EXTRACTION: Odds ratios and information on study quality were extracted from the selected articles by two independent reviewers. DATA SYNTHESIS: Five studies containing data on 2479 patients were included. Three of the five studies used medical or neurological patients as controls, the other two used population controls. Odds ratios for developing Creutzfeldt-Jakob disease from blood transfusion ranged from 0.54 to 0.89. Four of the five studies had confidence intervals that crossed 1.0. The combined odds ratio was 0.70 (95% confidence interval 0.54 to 0.89). CONCLUSIONS: Case-control studies do not suggest a risk of developing Creutzfeldt-Jakob disease from blood transfusion. Rather, a trend seems to exist towards a lower frequency of previous blood transfusion in patients with Creutzfeldt-Jakob disease than in controls. However, it is important to be aware of these studies' methodological limitations-primarily the choice of control population and reliability of recall of transfusion status.

Case-Control Studies↗
PubMed2000

Receptor revision of immunoglobulin heavy chain variable region genes in normal human B lymphocytes.

Contrary to the general precepts of the clonal selection theory, several recent studies have provided evidence for the secondary rearrangement of immunoglobulin (Ig) genes in peripheral lymphoid tissues. These analyses typically used transgenic mouse models and have only detected secondary recombination of Ig light chain genes. Although Ig heavy chain variable region (V(H)) genes encode a substantial element of antibody combining site specificity, there is scant evidence for V(H) gene rearrangement in the periphery, leaving the physiological importance of peripheral recombination questionable. The extensive somatic mutations and clonality of the IgD(+)Strictly-IgM(-)CD38(+) human tonsillar B cell subpopulation have now allowed detection of the first clear examples of receptor revision of human V(H) genes. The revised VDJ genes contain "hybrid" V(H) gene segments consisting of portions from two separate germline V(H) genes, a phenomenon previously only detected due to the pressures of a transgenic system.

Base Sequence↗
PubMed2000

Health care, federalism and the new Social Union.

The Social Union framework agreement and the Health Accord provide examples of the close relationship that exists between federalism and the delivery of health care. These recent agreements represent a move from a federal-unilateral style of federalism to a more collaborative model. This shift will potentially affect federal funding for health care, interpretation of the Canada Health Act and the development of new health care initiatives. The primary advantage of the new collaborative model is protection of jurisdictional autonomy. Its primary disadvantages are blurring of accountability and potential for exclusion of the public from decision-making.

Canada↗