PubMed Health⌕ Search

Biomedical subjects

D Haskard

Publications and source records attributed to D Haskard.

At least 19 recordsLinked to original sources
PubMed1998

Visualising E-selectin in the detection and evaluation of inflammatory bowel disease.

BACKGROUND: Vascular endothelial E-selectin expression is induced by proinflammatory cytokines and contributes to accumulation of leucocytes in tissues. AIMS: To investigate the role of E-selectin in inflammatory bowel disease (IBD). METHODS: E-selectin expression was assessed in patients with ulcerative colitis and Crohn's disease by measuring the concentration of circulating soluble E-selectin (sE-selectin) using ELISA, by immunohistochemistry of colonic biopsy specimens, and by abdominal immunoscintigraphy after injecting radiolabelled F(ab')2 fragment of a monoclonal anti-E-selectin antibody. The value of scintigraphy using anti-E-selectin was judged by a prospective comparative study of autologous leucocyte scanning and E-selectin antibody scanning in 17 patients with IBD. RESULTS: Circulating sE-selectin was elevated in patients with clinically active disease. Tissue expression of E-selectin was enhanced in patients with active inflammation, with weak or absent expression in inactive disease and healthy controls. In-111 labelled anti-E-selectin scintiscans were compared with Tc-99m labelled leucocyte scans performed 24 hours earlier. Twelve patients had areas of active inflammation on leucocyte scan while 11 patients had positive E-selectin scans. The results of the two scans were concordant in 14 patients, with those positive for both (10/17) showing similar disease localisation and extent. CONCLUSIONS: Tissue E-selectin and circulating sE-selectin are increased during active inflammatory bowel disease. Anti-E-selectin imaging with radiolabelled monoclonal antibody identified areas of inflammation in Crohn's disease and ulcerative colitis. The technique should prove useful clinically for identifying the site and extent of disease.

Acute Disease↗
PubMed1997

Improving wedged field dose distributions.

Dose profiles produced by wedge filters in the non-wedged direction can exhibit a 7% or greater dose reduction at the outer ends of the field compared with open field profiles. However, many planning systems use open field profiles to model wedged dose distributions. In the present work, wedges have been modified to reproduce open field profile shapes. This modification involved removing varying thicknesses of the wedge using a simple milling machine. The wedge thickness was calculated using the assumption that dose is proportional to primary collision kerma. The discrepancies in dose between wedged field and open field profile shapes of up to 7% were reduced to less than 3% with the modifications, even for varying depths and off-axis distances. The necessary measurements are simple to perform, and hence this technique could be applied to improve wedged field dose distributions in other radiotherapy departments.

Biophysical Phenomena↗
PubMed1994

Expression and shedding of intercellular adhesion molecule 1 and lymphocyte function-associated antigen 3 by normal and scleroderma fibroblasts. Effects of interferon-gamma, tumor necrosis factor alpha, and estrogen.

OBJECTIVE: To examine intercellular adhesion molecule 1 (ICAM-1) and lymphocyte function-associated antigen 3 (LFA-3) in cultures of normal and systemic sclerosis (SSc) dermal fibroblasts. METHODS: The surface and soluble forms of ICAM-1 and LFA-3 were measured by flow cytometry and capture enzyme-linked immunosorbent assay, respectively. RESULTS: Surface ICAM-1 was significantly higher on SSc fibroblasts compared with normal controls. Beta-estradiol did not directly enhance ICAM-1 or LFA-3 expression in either normal or SSc cells, but significantly augmented the cytokine-induced increase in ICAM-1. Soluble ICAM-1 (sICAM-1) and sLFA-3 were detected in fibroblast cultures. While no difference was found in the level of sLFA-3, the shedding of sICAM-1 was significantly increased (P < 0.001) in cells from SSc patients. CONCLUSION: SSc fibroblasts express intrinsically elevated levels of surface ICAM-1 and release higher levels of sICAM-1 in vitro. Increased expression of ICAM-1 by interferon-gamma and tumor necrosis factor alpha alone, and the further induction in combination with beta-estradiol may underlie an aspect of fibroblast dysfunction in SSc and the female predisposition to the disease.

Antigens, CD↗
PubMed1994

Circulating adhesion molecules in sarcoidosis.

Sarcoidosis is a disease of unknown etiology characterized by non-caseating granulomata together with a number of systemic abnormalities. We have recently shown these include increased expression of the integrins CD11/CD18 on peripheral blood leucocytes. Here we have measured serum levels of the adhesion molecules intercellular adhesion molecule-1 (ICAM-1), E-selectin and vascular cell adhesion molecule-1 (VCAM-1) in 23 patients and 14 normal controls using antigen capture sandwich ELISAs. Median circulating E-selectin levels in the patients were nearly three times those of the controls (P < 0.0001, Mann-Whitney U-test), whilst ICAM-1 but not VCAM-1 levels were only slightly elevated. These results show that endothelial cell activation and shedding of E-selectin into the circulation are additional features of the pathology of sarcoidosis.

Adult↗
PubMed1993

Intercellular adhesion molecules in normal synovium.

The vasculature of normal synovium and skin has been examined for the presence of molecules believed to be involved in intercellular adhesion and whose expression on endothelial cells in vitro is known to be upregulated by cytokines. Synovium was obtained from clinically and histologically normal joints removed during amputations for proximal sarcomata. Skin was obtained from healthy volunteers. Cryostat sections of tissues were assessed by immunohistochemistry and microdensitometry for the presence of E-selectin using monoclonal antibody 1.2B6, intercellular adhesion molecule-1 (ICAM-1) using monoclonal antibody 6.5B5 and vascular cell adhesion molecule (VCAM-1) using monoclonal antibody 1.4C3. Both E-selectin and ICAM-1 were present on a proportion of normal synovial venules but at a level comparable to or lower than that found on dermal vessels. (Staining intensities given as mean absorption indices: superficial synovium 1.2B6: 9.9 +/- 11.4, 6.5B5: 10.2 +/- 12.0, deep synovium 1.2B6: 6.6 +/- 9.9, 6.5B5: 24.6 +/- 15.7, skin 1.2B6: 13.1 +/- 16.6, 6.5B5: 36.4 +/- 12.9.) E-selectin expression was most prominent on small superficial venules in synovium and ICAM-1 most strongly expressed on larger, deep venules. VCAM-1 was found at low levels on cells associated with vessel walls but no significant endothelial staining was seen in either type of tissue. VCAM-1 was also present on cells of the synovial lining layer. Some of the findings in synovium could have been attributable to tumour related cytokine release, but the consistency of findings and comparability to skin suggest that this is relatively unlikely.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
PubMed1992

Detection of cytokines at the site of tuberculin-induced delayed-type hypersensitivity in man.

Cytokines are chiefly local mediators which play an important role in the regulation of the cell-cell interactions which may be involved in the development of the delayed-type hypersensitivity (DTH) reaction. Using immunohistochemical techniques, the presence of IL-1 alpha, IL-1 beta, IL-6, interferon-gamma (IFN-gamma) and tumour necrosis factor-alpha (TNF-alpha) in the skin in tuberculin-purified protein derivative (PPD)-induced DTH reactions was investigated in six normal individuals. Cells staining for these cytokines were first observed 6 h after PPD challenge, and they were detected throughout the duration of the 7-day experiment. The number of cells staining for IFN-gamma reached a peak at 48 h, where 33% of the total aggregate cells were positive, but declined thereafter to 3% at day 7. On the other hand, the number of cells staining for TNF-alpha and IL-1 persisted at high levels throughout the observation period of 7 days (e.g. at 48 h and thereafter, about 40% cells positive for TNF-alpha and 20% for IL-1 alpha and IL-1 beta). Double immunofluorescence and staining on sequential sections showed that IFN-gamma-staining cells were CD3+ T cells; TNF-alpha, IL-1 and IL-6 staining cells were mainly of the CD68+ macrophages/monocytes and that 80% of the CD1a+ cells (Langerhans-like cells) in the dermis contained TNF-alpha and IL-1. The presence of these cytokines at the site of inflammation suggests that they may be locally produced by the inflammatory cells. Their persistence during the reaction suggests that they are intimately associated with this response, and are involved in the development of the reaction.

B-Lymphocytes↗
PubMed1992

Intercellular adhesion molecule-1 (ICAM-1) and endothelial leucocyte adhesion molecule-1 (ELAM-1) expression in the bronchial mucosa of normal and asthmatic subjects.

Bronchial lavage and biopsy studies suggest the involvement of eosinophils and T-lymphocytes in allergic inflammation in asthma. There is evidence suggesting that the expression of adhesion molecules on endothelial cells and of their receptors on leucocytes is involved in this process. To investigate these mechanisms we have obtained bronchial mucosal biopsies from 10 normal subjects and from 10 symptomatic atopic asthmatics. Six of the asthmatics were re-biopsied after 6 weeks of inhaled beclomethasone dipropionate (BDP) during which time their clinical response was monitored. Frozen sections were stained by the immunoperoxidase method using monoclonal antibody (MoAb) 6.5B5 to identify expression of intercellular adhesion molecule (ICAM-1) and MoAb 1.2B6 for endothelial leucocyte adhesion molecule (ELAM-1). Araldite-embedded sections were also stained for eosinophils using MoAb EG2 to identify eosinophilic cationic protein (ECP). A significant mucosal eosinophilia was apparent in the asthmatic but not in the normal biopsies. Immunostaining for ICAM-1 was observed in both the epithelium and endothelium and ELAM-1 in endothelium, with no significant differences being apparent between the asthmatic and normal subjects. Topical BDP markedly reduced the mucosal eosinophilia without affecting the expression of either adhesion molecule. Using this method, we conclude that there is basal expression of ICAM-1 and ELAM-1 in normal human bronchial mucosa, which is not significantly different from that in asthmatics, and that it is insensitive to suppression with corticosteroids at an inhaled dose that causes clinical improvement.

Adult↗
PubMed1990

Novel antibodies associated with unexplained loss of renal allografts.

Using an endothelial/epithelial hybrid cell line, three different non-HLA antibody types have been identified by flow cytometry in patients who have rapidly rejected multiple renal allografts. These antibodies may be classified as anti-endothelial-monocyte, anti-activated endothelial cell, or anti-epithelial cell.

Antibodies↗
PubMed1989

Lipoxin A4 and lipoxin B4 inhibit chemotactic responses of human neutrophils stimulated by leukotriene B4 and N-formyl-L-methionyl-L-leucyl-L-phenylalanine.

1. Lipoxin A4 (LXA4) and lipoxin B4 (LXB4) have been evaluated for their capacities to modulate neutrophil (PMN) migration and endothelial cell adherence using compounds prepared by total chemical synthesis. 2. Increased PMN migration was seen with concentrations of LXA4 from 10(-9) mol/l to 10(-7) mol/l. LXA4 was 100-fold less potent than leukotriene B4 (LTB4) and it elicited only one-half of the maximal response of LTB4. 3. The (5S,6S,15S)-isomer of LXA4 induced only a weak migratory response and LXB4 was inactive, suggesting that the activity of LXA4 was stereospecific. 4. Modified chequerboard analysis indicated that LXA4 was a chemokinetic agent. 5. Preincubation of PMN with increasing concentrations of LXA4 induced a very similar dose- and time-dependent inhibition of the subsequent response to 10(-7) mol/l LTB4 or 10(-7) mol/l N-formyl-L-methionyl-L-leucyl-L-phenylalanine (FMLP). The inhibition was observed at 10(-10) mol/l LXA4; the concentration which produced 50% inhibition was 10(-8) mol/l and 100% inhibition of PMN locomotion occurred at 10(-6) mol/l LXA4. 6. The (5S,6S,15S)-isomers of LXA4 and LXB4 were 5- and 100-fold less potent than LXA4, respectively, in suppressing LTB4- or FMLP-induced PMN migration. 7. Preincubation of PMN with LXA4 led to a suppression of calcium mobilization, as assessed by Quin2-AM fluorescence, when the cells were subsequently stimulated under optimal conditions by LTB4 or FMLP. 8. These results suggest that the inhibitory activity of lipoxins may be related to the capacity of these molecules to regulate calcium ion mobilization.

Calcium↗
PubMed1988

The preferential accumulation of helper-inducer T lymphocytes in inflammatory lesions: evidence for regulation by selective endothelial and homotypic adhesion.

The mechanisms which lead to the accumulation of T lymphocytes into inflammatory lesions are not clearly understood. We have previously shown that synovial CD4 T lymphocytes are mostly CDw29+UCHL1+ (helper-inducer cells) and very few carry the CD45R antigen which identifies the suppressor-inducer subset. Synovial CD8+ cells are also CDw29+UCHL1+CD45R-. In the present study, lymphocytes from pleural and peritoneal inflammatory infiltrates were shown to have a similar phenotypic pattern. Furthermore, it was demonstrated that the CDw29+UCHL1+ subset had a greater ability than CD45R+ cells to adhere to endothelial cells and to form homotypic clusters. Differential surface expression of LFA-1 on the two subsets was also shown, but this could not account for the demonstrated adhesion differences. Differences in adhesion between CDw29+/UCHL1+ and CD45R+ cells may explain the preferential accumulation of CDw29+/UCHL1+ cells in inflammatory infiltrates and underlie some of the functional differences between cells taken from sites of chronic inflammation and those from peripheral blood.

Antigens, Differentiation↗
PubMed1987

Superinduction of T lymphocyte-endothelial cell (EC) binding by treatment of EC with interleukin 1 and protein synthesis inhibitors.

We have previously reported that marked enhancement of the in vitro binding of lymphocytes to endothelial cell (EC) monolayers is observed after stimulation of the EC with interleukin 1 (IL 1). To determine whether new protein synthesis was required for this effect of IL 1, EC were incubated with IL 1 in the presence of cycloheximide or puromycin. Three different effects of these protein synthesis inhibitors on T-EC binding were observed. First, preincubation of the EC with both IL 1 and an inhibitor blocked the increase in binding if the inhibitor was present during both the preincubation and the 1 hr duration of the T-EC binding assay, suggesting that new protein synthesis is required for the enhancement of T-EC adhesion by IL 1. Second, preincubation of the EC with low doses of the inhibitors (0.1 to 1 microgram/ml) in the absence of IL 1 consistently increased T-EC binding, even if the inhibitors were present during the T-EC adhesion assay; in addition, the inhibitors additionally increased the stimulatory effect of IL 1 if the EC were washed free of the inhibitor before the assay step. The binding-enhancing effect of low concentrations of cycloheximide could be inhibited by an antibody to the CDw18 complex on the T cell, suggesting an up-regulation of the ligand on the EC involved in CDw18-dependent T cell adhesion. Third, higher concentrations of the inhibitors (3 to 10 micrograms/ml) were toxic for the EC in the presence of IL 1, possibly due to the combined blocking effect of IL 1 and inhibitors on EC protein synthesis.

Antigens, Surface↗
PubMed1987

Pathways to chronic inflammation in rheumatoid synovitis.

Postcapillary venules resembling the high endothelial venules (HEVs) of lymphoid tissues have often been observed at sites of chronic inflammation. We have therefore postulated that such venules may be an important site of lymphocyte migration into rheumatoid synovial membrane and that inflammatory cell products may act on endothelial cells (ECs) to increase lymphocyte emigration. Electron microscopic examination of rheumatoid synovial membranes showed that a strong correlation existed between the proportion of lymphocytes in perivascular tissue and the height/base ratio of the ECs in those areas. In addition, binding experiments showed that peripheral blood mononuclear cells preferentially bound to ECs in sections of rheumatoid synovial membrane that had the morphological appearance of HEVs. In vitro binding experiments, in which lymphocyte adhesion to human umbilical vein EC monolayers was measured, showed that adhesion was enhanced by preincubation of the ECs with interferon-gamma or interleukin 1 (IL 1). The central role of IL 1 in increasing lymphocyte migration into the rheumatoid synovial membrane was also supported by the findings that IL 1 is chemotactic for lymphocytes, ECs can secrete IL 1, and IL 1 activity is readily detectable in synovial fluids of rheumatoid arthritis patients.

Arthritis, Rheumatoid↗