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Biomedical subjects

L J Walton

Publications and source records attributed to L J Walton.

10 recordsLinked to original sources
PubMed2000

Outreach to public health professionals: lessons learned from a collaborative Iowa public health project.

In 1995, the National Library of Medicine (NLM) and the Public Health Service (PHS) recommended that special attention be given to the information needs of unaffiliated public health professionals. In response, the National Network of Libraries of Medicine (NN/LM) Greater Midwest Region initiated a collaborative outreach program for public health professionals working in rural east and central Iowa. Five public health agencies were provided equipment, training, and support for accessing the Internet. Key factors in the success of this project were: (1) the role of collaborating agencies in the implementation and ongoing success of information access outreach projects; (2) knowledge of the socio-cultural factors that influence the information-seeking habits of project participants (public health professionals); and (3) management of changing or varying technological infrastructures. Working with their funding, personnel from federal, state, and local governments enhanced the information-seeking skills of public health professionals in rural eastern and central Iowa communities.

Computer Communication Networks↗
PubMed1999

Inhibition of prostaglandin E2 synthesis in abdominal aortic aneurysms: implications for smooth muscle cell viability, inflammatory processes, and the expansion of abdominal aortic aneurysms.

BACKGROUND: There is no treatment proven to limit the growth of abdominal aortic aneurysms, in which the histological hallmarks include inflammation and medial atrophy, with apoptosis of smooth muscle cells and destruction of elastin. METHODS AND RESULTS: Aneurysm biopsies were used for explant cultures, the preparation of smooth muscle cell cultures, and isolation of macrophages. Tissue macrophages stained strongly for cyclooxygenase 2. Prostaglandin E2 (PGE2) concentrations in aneurysm tissue homogenates, conditioned medium from explants, and isolated macrophages were 49+/-22 ng/g, 319+/-38 ng/mL, and 22+/-21 ng/mL, respectively. PGE2 inhibited DNA synthesis and proliferation in normal aortic smooth muscle cells (IC50, 23.2+/-3.8 and 23.6+/-4.5 ng/mL, respectively). In smooth muscle cells derived from aneurysmal aorta, PGE2 also caused cell death, with generation of oligonucleosomes. Conditioned medium from the mixed smooth muscle and monocyte cultures derived from explants also had potent growth-inhibitory effects, and fractionation of this medium showed that the growth-inhibitory molecule(s) coeluted with PGE2. In explants, indomethacin 10 micromol/L or mefenamic acid 10 micromol/L abolished PGE2 secretion and significantly reduced IL-1beta and IL-6 secretion. In a separate case-control study, the expansion of abdominal aortic aneurysms was compared in 15 patients taking nonsteroidal anti-inflammatory drugs and 63 control subjects; median growth rates were 1.5 and 3.2 mm/y, respectively, P=0.001. CONCLUSIONS: The adverse effects of PGE2 on aortic smooth muscle cell viability and cytokine secretion in vitro and the apparent effect of anti-inflammatory drugs to lower aneurysm growth rates suggest that selective inhibition of PGE2 synthesis could be an effective treatment to curtail aneurysm expansion.

Adolescent↗
PubMed1999

The influence of indomethacin on the metabolism and cytokine secretion of human aneurysmal aorta.

INTRODUCTION: inflammation and proteolysis are important processes in the development of abdominal aortic aneurysms (AAAs). Prostaglandin E2 (PGE2) (a product of cyclo-oxygenase 2), other inflammatory mediators and proteolytic enzymes are produced in high quantities in the aneurysm wall. We developed an explant culture system for AAA tissue to assess the effects of potential drug therapies. METHODS: full thickness biopsies of human AAA were established in culture in the presence or absence of indomethacin (a cyclo-oxygenase-2 inhibitor). The conditioned medium was collected at 48 h intervals and analysed for products of collagen breakdown, matrix metalloproteinases, PGE2 and inflammatory cytokines. Explant viability was assessed by histology, glucose consumption, lactate dehydrogenase release and demonstration of protein synthesis in the tissue. RESULTS: nuclear morphology was maintained for 4 or more days and this, together with biochemical assays, indicated that AAA explants were viable in short-term culture. Indomethacin (10 microM) markedly reduced AAA explant production of prostaglandin E2 from 320 ng/ml to 3.3 ng/ml (p=0.028, n=6). Indomethacin also reduced the release of interleukin-1beta (IL-1beta) (from 166 pg/ml to 9.8 pg/ml, p =0.04, n=5) and interleukin-6 (IL-6) (from 119 ng/ml to 57 ng/ml, p=0.028, n=6), but had no effect on monocyte chemotactic protein 1 or matrix metalloproteinase-9 secretion. CONCLUSIONS: short-term explants of AAA are a novel method to assess the effects of drugs on aneurysm tissue. Indomethacin reduces the production of PGE2, IL-1beta and IL-6, suggesting that cyclo-oxygenase-2 inhibitors may control the inflammation in the aneurysm wall and potentially limit AAA growth.

Aorta, Abdominal↗
PubMed1998

Intra-epithelial subpopulations of T lymphocytes and Langerhans cells in oral lichen planus.

This study has addressed the question of whether there is selective recruitment and distribution of intra-epithelial leucocytes in lesions of oral lichen planus (OLP). T-lymphocyte subsets were examined in the epithelium and peripheral blood of patients and controls using flow cytometry and double immunofluorescence, and the relationship between keratinocyte intercellular adhesion molecule-1 (ICAM-1) expression with T-lymphocyte and Langerhans cell (LC) distribution was examined. The circulating 'memory' subset (CD45RO+) of T-helper cells (CD4+) was increased from 49.1% in controls to 65.7% in patients (P=0.005), while the 'naive' subset (CD45RA+), which was absent from control epithelium, comprised 24% of helper cells in OLP (P=0.016). Fewer LC expressed CD45RO in OLP than in controls (P=0.037) and all T-cell and LC counts were significantly raised in ICAM-1-expressing areas of epithelium. These data demonstrate changes in intra-epithelial T-lymphocyte and LC populations compared with normal oral mucosa and suggest there is selective recruitment in OLP. In addition, keratinocyte ICAM-1 expression does appear to be associated with accumulation of infiltrating T lymphocytes and LC.

CD4-Positive T-Lymphocytes↗
PubMed1997

Unrestricted usage of immunoglobulin heavy chain genes in B cells infiltrating the wall of atherosclerotic abdominal aortic aneurysms.

The aim of this study was to provide evidence for the hypothesis that the B cell rich infiltrate concentrated in the adventitia of atherosclerotic abdominal aortic aneurysms is an autoimmune response to specific tissue antigens. Detailed histological examination of biopsies from 26 atherosclerotic abdominal aortic aneurysms showed in the adventitia, the presence of lymphoid follicles in 7/26 (27%) and of plasma cells in all cases. DNA prepared from the outer aneurysm wall (n = 25) was amplified using the polymerase chain reaction to investigate the repertoire of the immunoglobulin heavy chain (VH) genes used. Amplification of the VDJ region of VH, using both framework 2 and 3 primers, revealed unrestricted usage of the VH gene in 24/25 cases. The only case where restricted usage of the VH genes was observed, might have been attributable to severe virally-induced tissue inflammation. These results indicate that, in the vast majority of atherosclerotic abdominal aortic aneurysms, the B cell rich adventitial infiltrates are not an autoimmune response to a limited repertoire of tissue antigens.

Aged↗
PubMed1997

Cutaneous lymphocyte associated antigen (CLA) and alpha e beta 7 integrins are expressed by mononuclear cells in skin and oral lichen planus.

The cutaneous lymphocyte associated- (CLA-) positive subset of lymphocytes appears to migrate preferentially into skin by interacting with E-selectin on vascular endothelium; lymphocytes expressing the alpha e beta 7 integrin accumulate preferentially in the epithelium of the gastrointestinal tract. To determine whether the mononuclear cell population of the oral mucosa resembles that of the skin or intestine, and using lichen planus as a model, the proportions of CLA- and alpha e beta 7-positive cells in the epithelium, lamina propria and peripheral blood were compared by immunostaining and flow cytometry. In both skin and oral lichen planus, selective accumulation of CLA-positive cells was seen in the epithelium but not in the lamina propria. In contrast, large numbers of alpha e beta 7-positive intraepithelial cells were found in oral but not in skin lichen planus. These results show that in terms of CLA and alpha e beta 7 expression there are important differences in the mononuclear cell population of oral mucosa and skin.

Adolescent↗
PubMed1996

T cell antigen receptor expression by intra-epithelial lymphocytes in oral lichen planus.

The distribution of T lymphocytes expressing the alpha beta or gamma delta heterodimer of the T cell receptor (TCR) was examined in normal oral mucosa (NOM) and reticular oral lichen planus (OLP) using a panel of antibodies specific for CD3, the alpha beta TCR and the gamma delta TCR. Intra-epithelial lymphocytes were counted and epithelial surface length was measured by image analysis. T cells in the lamina propria were not quantified. Total intra-epithelial lymphocytes were increased in OLP compared with NOM (P = 0.0004). The proportions of cells expressing the gamma delta TCR in NOM and OLP were 10% and 9.3%, respectively, suggesting there is no selective recruitment from the circulation of either alpha beta or gamma delta TCR-bearing cells into normal oral epithelium or that affected by OLP. The role, if any, of gamma delta T cells in the pathogenesis of OLP remains to be determined.

Antibodies, Monoclonal↗
PubMed1994

VCAM-1 and ICAM-1 are expressed by Langerhans cells, macrophages and endothelial cells in oral lichen planus.

Expression of intercellular adhesion molecule-1 (ICAM-1, CD54) and vascular cell adhesion molecule-1 (VCAM-1, CD106) was examined in oral lichen planus (OLP) and normal oral mucosa (NOM). Immunoperoxidase staining showed ICAM-1 expression by vascular endothelium in all biopsies of OLP and NOM whereas endothelial VCAM-1 staining was found in 2/7 NOM and 8/9 OLP. In the lamina propria of NOM occasional cells were ICAM-1 or VCAM-1 positive, and virtually no staining of intraepithelial dendritic cells was seen for either marker. Intraepithelial dendritic cells stained for ICAM-1 in 7/9 and VCAM-1 in 4/9 OLP biopsies. Double immunofluorescence showed dual labelling of Langerhans cells (LC) with CD1a and VCAM-1 in a further 5/12 cases of OLP, but there was no such staining in four NOM. This is the first report of LC staining with VCAM-1. Induction of ICAM-1 and VCAM-1 on LC and macrophages in OLP suggests these cells are activated and may contribute to the pathogenesis of OLP by presenting antigen to infiltrating lymphocytes.

Animals↗