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W J Stevens

Publications and source records attributed to W J Stevens.

At least 37 records · Page 2Linked to original sources
PubMed2002

Validation of a two-color flow cytometric assay detecting in vitro basophil activation for the diagnosis of IgE-mediated natural rubber latex allergy.

BACKGROUND: IgE-dependent triggering of basophils not only elicits the release of different mediators but also the up-regulation of certain markers, e.g. CD63, which can be detected by flow cytometry. We intended to investigate if flow cytometric analysis of basophil activation could be a valuable tool in the diagnosis of latex allergy, and to evaluate if the basophil activation test (BAT) could be helpful in determining the clinical significance of a positive latex IgE in individuals with negative history and negative latex skin test. Additionally we aimed to determine the role of cross-reactive carbohydrate determinants (CCDs) in causing positive latex IgE without apparent clinical significance. METHODS: Twelve healthy controls without a history of latex hypersensitivity with a negative latex IgE and skin test (group 1), 24 individuals without a history of latex hypersensitivity with a negative latex IgE and skin test but with other inhalant allergies (group 2), and 29 latex allergic patients with a compelling history of latex allergy with a positive latex IgE and prick test (group 3) were enrolled. The diagnostic performances of the BAT were further evaluated in 13 individuals with a history of latex allergy but with negative specific IgE and/or skin test (group 4). Twenty-four individuals with positive latex IgE without apparent clinical relevance, i.e. without history of latex hypersensitivity and negative latex skin tests, were also analyzed (group 5). The putative role of CCDs causing positive latex IgE results without apparent clinical significance was evaluated by quantification of IgE for bromelain. RESULTS: According, to the receiver operating characteristics(ROC)-generated threshold value of 17% between latex allergic patients and the pooled group of nonlatex allergic individuals, the sensitivity and specificity of the basophil activation test was 93.1% and 91.7%, respectively. In healthy controls, allergic patients without latex hypersensitivity and latex allergic patients the number of positive BATs was 0/12, 3/24 and 27/29, respectively. In the individuals with an evocative history of latex allergy but with negative latex IgE and/or skin test the BAT was positive in all 13 cases. Twenty of 24 individuals without apparent latex allergy but with positive latex IgE had a negative BAT. IgE for bromelain was positive in 1/19 sera from group 2, 1/24 sera from group 3, none of the 8 sera from group 4, but in 16/18 sera from group 5, respectively. CONCLUSION: Flow cytometric analysis of activated basophils seems a highly sensitive and specific tool for diagnosing latex allergy. In addition, the technique might help to determine the clinical relevance of positive IgE quantification in the absence of overt latex allergy. CCDs of natural rubber latex allergens were confirmed to mimic latex sensitization.

Basophils↗
PubMed2002

Combined endurance/resistance training reduces plasma TNF-alpha receptor levels in patients with chronic heart failure and coronary artery disease.

AIMS: Physical reconditioning of patients with chronic heart failure (CHF) improves exercise capacity and restores endothelial function and skeletal muscle changes. The effects of 4 months combined endurance/resistance exercise training on cytokines and cytokine receptors in patients with CHF were studied. In addition, changes in submaximal and maximal exercise performance were addressed. METHODS AND RESULTS: Twenty-three patients with stable CHF due to coronary artery disease (CAD, n=12) or idiopathic dilated cardiomyopathy (IDCM, n=11) were trained for 4 months. Blood sampling for measurement of plasma concentrations (ELISA) of interleukin (IL)-6, tumour necrosis factor (TNF)-alpha, soluble TNF receptor 1 (sTNFR1) and 2 (sTNFR2), as well as cardiopulmonary exercise testing were performed at baseline and after 4 months. Training induced a significant decrease in sTNFR1 (P=0.02) for the total population, and in both sTNFR1 (P=0.01) and sTNFR2 (P=0.02) concentrations for the CAD group only. IL-6 and TNF-alpha levels were not altered. Cytokine concentrations remained unchanged in an untrained age- and sex-matched control group. NYHA functional class, submaximal and maximal workrate were significantly improved in both patient groups. Oxygen uptake at the anaerobic threshold (P=0.002) and at peak exercise increased in the CAD patients only (P=0.008). CONCLUSION: Besides an overall beneficial effect on exercise capacity, combined endurance/resistance exercise training has an anti-inflammatory effect in patients with CHD and CAD.

Adult↗
PubMed2002

Effect of bisphosphonates on viability, proliferation, and dexamethasone-induced apoptosis of articular chondrocytes.

BACKGROUND: Bisphosphonates (BP) increase bone mass in patients with rheumatoid arthritis and are effective in the prevention and treatment of steroid-induced osteoporosis. However, little is known about their direct effects on chondrocytes. OBJECTIVES: To study the influence of BP on articular chondrocytes in vitro and to investigate whether BP can prevent steroid-induced apoptosis of articular chondrocytes. METHODS: Bovine articular chondrocytes were cultured and incubated with different concentrations of clodronate, pamidronate, risedronate, or dexamethasone. In the second part of the study, BP were added to the chondrocyte cultures one hour before co-incubation with dexamethasone. Viability and proliferation were evaluated using propidium iodide staining and tritium labelled thymidine incorporation. Apoptosis was measured with annexin V staining or the TUNEL method. RESULTS: Only high concentrations (>10(-6) mol/l) of clodronate, pamidronate, and risedronate induced a decrease in the viability and proliferation of chondrocytes. None of the BP at concentrations ranging from 10(-12) to 10(-3) mol/l induced apoptosis. Growth retardation and apoptosis induced by dexamethasone (10(-7) mol/l) was prevented by addition of pamidronate (10(-6) mol/l) or risedronate (10(-8) or 10(-6) mol/l). CONCLUSION: Bisphosphonates in therapeutic concentrations are safe for articular chondrocytes in vitro. Moreover, pamidronate and risedronate prevent dexamethasone-induced growth retardation and apoptosis of chondrocytes. These findings add evidence for a chondroprotective effect of nitrogen-containing BP, especially in patients treated with corticosteroids.

Animals↗
PubMed2001

Evaluation of monensin and brefeldin A for flow cytometric determination of interleukin-1 beta, interleukin-6, and tumor necrosis factor-alpha in monocytes.

Flow cytometry has become a powerful technique to measure intracellular cytokine production in lymphocytes and monocytes. Appropriate inhibition of the secretion of the produced cytokines is required for studying intracellular cytokine expression. The aim of this study was to compare the capacity of cytokine secretion inhibitors, monensin and brefeldin A, in order to trap cytokine production (interleukin-1 beta [IL-1beta], IL-6, tumor necrosis factor-alpha [TNF-alpha]) within peripheral blood monocytes. A two-color flow cytometric technique was used to measure intracellular spontaneous and lipopolysaccharide (LPS)-stimulated IL-1beta, IL-6, and TNF-alpha production in monocytes (CD14+) of whole blood cultures. The viability of monensin-treated monocytes was slightly lower than that of brefeldin A-inhibited monocytes, as measured with propidium iodide (PI). The percentage of IL-6 and TNF-alpha-producing monocytes after 8 h of culture without stimulation revealed significant lower values for monensin-treated than for brefeldin A-treated monocytes. The percentages for stimulated cells did not differ. The spontaneous intracellular production in molecules of equivalent soluble fluorochrome units (MESF) of IL-1beta, IL-6, and TNF-alpha after 8 h of culture was higher in brefeldin A than in monensin-inhibited monocytes. The LPS-stimulated intracellular production of IL-1beta, IL-6, and TNF-alpha was increased in brefeldin A-inhibited monocytes. In conclusion, for flow cytometric determination of intracellular monocytic cytokines (IL-1beta, IL-6, and TNF-alpha), brefeldin A is a more potent, effective, and less toxic inhibitor of cytokine secretion than monensin.

Adult↗
PubMed2001

IgE-mediated anaphylaxis after first intravenous infusion of cyclosporine.

BACKGROUND: Intravenous administration of cyclosporine, which contains Cremophor EL (a polyethoxylated castor oil; BASF, Berlin, Germany), has occasionally resulted in an anaphylactic reaction. An apparent hypersensitivity reaction (bronchospasm and decrease in blood pressure) had occurred during heart transplantation in a 59-year-old woman after intravenous infusion of cyclosporine. Subsequent oral administration of cyclosporine precipitated no reaction. OBJECTIVE: The purpose of this study was to attempt to ascertain the mechanism responsible for the anaphylactic reaction. METHODS: Hypersensitivity investigations, including total serum IgE and allergen-specific IgE quantifications, skin testing, and basophil activation tests by flow cytometric determination of CD63 upregulation were undertaken in the study patient and in two healthy control subjects who were free of medication. RESULTS: The results of intradermal testing with Cremophor EL were positive after 15 minutes in the study patient only. Both cyclosporine and Cremophor EL induced considerable activation of the basophils from our study patient, with an upregulation of CD63 expression from 1% to 39% and 55%, respectively. In contrast, the expression of CD63 on basophils from the two control subjects remained essentially unchanged. CONCLUSIONS: The negative investigative findings in the control subjects, the patient's clinical manifestations in temporal relationship to the infusion, her positive results on intradermal testing with Cremophor, the basophil activation test results, and her uneventful course after oral administration of cyclosporine strongly support the presence of IgE antibodies to Cremophor EL in our patient.

Anaphylaxis↗
PubMed2001

Wasp venom immunotherapy induces a shift from IL-4-producing towards interferon-gamma-producing CD4+ and CD8+ T lymphocytes.

BACKGROUND: Venom immunotherapy (VIT) has proven to be very effective in hymenoptera venom anaphylaxis. However, the underlying immunoregulatory mechanisms of venom immunotherapy remain poorly understood. Recent studies measured the total amount of cytokine in culture supernatans, suggesting a shift in cytokine production from Th2 to a Th1 cytokine profile during VIT. We wanted to examine the contribution of specific T lymphocyte subpopulations, which is impossible using an extracellular method to determine cytokines in supernatants. OBJECTIVE: The present study was designed to evaluate the effect of VIT on the percentages of type 1 (IL-2, interferon-gamma (IFN-gamma)) and type 2 (IL-4) CD4+ and CD8+ T lymphocytes of patients with wasp venom anaphylaxis during immunotherapy. METHODS: Peripheral blood mononuclear cells of 20 individuals with a history of wasp sting anaphylaxis and a positive serum wasp venom specific IgE were isolated and in vitro stimulated with phorbol-12-myristate-13-acetate and ionomycin before VIT, at the end of a 5-day semirush VIT and at 6 months during VIT. Three-colour flow cytometric analysis was used for intracellular cytokine (IL-2, IFN-gamma, IL-4) detection in CD4+ (CD3+CD8-) T lymphocytes and CD8+ (CD3+CD8+) T lymphocytes. RESULTS: At the end of a 5-day semirush VIT, there was a significant decrease in percentage of IL-4-producing CD4+ and CD8+ T cells, compared with cytokine-producing cells before VIT (P = 0.0002 and 0.004). After 6 months of VIT, patients showed an increased number of IL-2-producing stimulated CD4+ and CD8+ lymphocytes compared with values before VIT (P = 0.002 and P = 0.0003). A higher amount of IFN-gamma-producing stimulated CD4+ and CD8+ cells was found after 6 months of VIT (P = 0.001 and P = 0.0006). There was no correlation between cytokine-producing cells and specific IgE for wasp. CONCLUSION: Venom immunotherapy induced a shift from IL-4-producing towards IFN-gamma-producing CD4+ as well as CD8+ T lymphocytes.

Adolescent↗
PubMed2001

CT of angioedema of the small bowel.

OBJECTIVE: The purpose of this study was to determine the added diagnostic value of CT for the diagnosis of visceral angioedema. CONCLUSION: Thickening of the small-bowel wall and mucosa with increased contrast enhancement, depiction of more layers of the small-bowel wall than normal, prominent mesenteric vessels, ascites, and fluid accumulation in the small bowel or together in the small bowel and the colon were the most significant CT findings in three patients with visceral angioedema. Findings appear to be transient.

Adult↗
PubMed2001

Influence of longterm therapy with methotrexate and low dose corticosteroids on type 1 and type 2 cytokine production in CD4+ and CD8+ T lymphocytes of patients with rheumatoid arthritis.

OBJECTIVE: Rheumatoid arthritis (RA) is a chronic inflammatory disease with predominance of type I cytokine [interleukin 2 (IL-2), interferon-gamma (IFN-gamma)] production. In this prospective study, we evaluated the influence of longterm therapy with methotrexate (MTX) in combination with low dose corticosteroids on the type 1/type 2 cytokine balance in RA. METHODS: Peripheral blood mononuclear cells were isolated from 10 controls and 20 patients with RA before therapy and after 12 mo of therapy with MTX in combination with low dose corticosteroids. Using flow cytometry, the intracellular production of IL-2, IFN-gamma, and IL-4 was measured in CD4+ and CD8+ T lymphocytes. RESULTS: Compared with healthy controls, patients with RA before therapy showed an increased percentage of IL-2 positive CD4+ and CD8+ T cells (p = 0.002, p = 0.01, respectively). An increased percentage of IFN-gamma positive CD8+ T cells was found (p = 0.0006) compared with the control group. After 12 months of therapy, a significantly decreased percentage of IL-2 positive CD4+ T cells and IFN-gamma positive CD4+ and CD8+ T lymphocytes was observed (p = 0.0003, p = 0.0007, p = 0.001). The percentage of IL-4/IFN-gamma positive CD4+ and CD8+ T cells was significantly higher after 12 months of therapy (p = 0.01, p = 0.02). There was a positive correlation between the percentage of IFN-gamma positive CD4+ T cells and disease activity variables (Ritchie Index and number of swollen joints) in RA patients before therapy (r = 0.6, p = 0.04 and r = 0.4, p = 0.05). CONCLUSION: Longterm therapy with MTX in combination with low dose corticosteroids for RA influenced the predominance of type 1 cytokines toward normalization of the cytokine balance in both CD4+ and CD8+ T lymphocytes.

Adrenal Cortex Hormones↗
PubMed2000

High bone mass and hypocalcaemic myopathy in a patient with idiopathic hypoparathyroidism.

The clinical manifestations of hypoparathyroidism are mainly characterised by increased neuromuscular irritability as a consequence of hypocalcaemia. Occasionally, elevation of the muscle enzymes may mimic polymyositis. Reduced parathyroid hormone production, but also vitamin D treatment and calcium supplementation, may contribute to the increased bone mass found in patients with postsurgical hypoparathyroidism. We report the case of a 36-year-old woman with untreated idiopathic hypoparathyroidism and a high bone mass despite severe muscle impairment due to hypocalcaemic myopathy.

Absorptiometry, Photon↗
PubMed2000

Long-term effects of specific immunotherapy, administered during childhood, in asthmatic patients allergic to either house-dust mite or to both house-dust mite and grass pollen.

In a retrospective study, asthmatic patients allergic to either house-dust mite (HDM) (Dermatophagoides pteronyssinus) (n = 34) or to both HDM and grass pollen (GP) (n = 14), and who were treated with specific immunotherapy (SIT) during childhood (mean duration of SIT: 61 +/- 9.70 months), were re-evaluated in early adulthood after mean cessation of SIT for 9.3 +/- 2.76 years. The results were compared to those of a control group of asthmatic patients (n = 42) with comparable asthma features, who were treated with appropriate antiasthmatic drugs during childhood, but who never received SIT. Re-evaluation was carried out with a standardized questionnaire, skin prick tests (SPT), and lung-function assessments. At the time of re-evaluation, the mean age in the SIT-treated group was 23.1 +/- 3.50 years; in the control group, it was 22.7 +/- 3.40 years. At re-evaluation, the risk of frequent asthmatic symptoms was three times higher in the control group than in the SIT-treated group (prevalence ratio: 3.43; P = 0.0006). The frequent use of antiasthmatic medication was also more pronounced in the control group, although the difference was not statistically significant (P=0.38). Lung-function parameters and results of SPT with HDM were comparable in both groups. It is concluded that SIT has long-term effects on asthmatic symptoms in young adults.

Adult↗
PubMed2000

Determination of T-cell subpopulations and intracellular cytokine production (interleukin-2, interleukin-4, and interferon-gamma) by cord blood T-lymphocytes of neonates from atopic and non-atopic parents.

This report describes the results of a prospective study on immunological markers in cord blood for the prediction of allergic diseases in children. First we evaluated methodological aspects of the flow cytometric technique on cord blood cytokine measurements. Subsequently, the T-cell subsets and percentage of cytokine-producing cord blood T-helper (Th) and T-suppressor/cytotoxic lymphocytes of neonates from atopic and non-atopic parents were compared. A group of 33 healthy, full-term newborn infants of whom 23/33 were at risk for atopy (i.e. having at least one parent with one or more atopic symptoms and positive specific immunoglobulin E [IgE] to at least one common inhalant allergen) was studied. A flow cytometric technique was used to analyze cord blood T-cell subsets and to determine the percentage of interleukin (IL)-2-, IL-4-, and interferon-gamma (IFN-gamma)-producing cord blood Th and T-suppressor/cytotoxic lymphocytes following stimulation with phorbol 12-myristate 13-acetate (PMA) and ionomycin. The percentage of CD3 (T lymphocytes), CD3+ CD4+ (Th lymphocytes), CD3+ CD8+ (T-suppressor/cytotoxic lymphocytes), CD19+ (B lymphocytes), CD3+ CD4+ CD45RO+ (memory Th lymphocytes), and CD3+ CD4+ CD45RA+ (naive Th lymphocytes) cells was unrelated to parental atopic status. PMA stimulation augmented the percentage of IL-2- and IFN-gamma-producing Th and T-suppressor/cytotoxic lymphocytes, whereas the number of IL-4-producing T lymphocytes remained very low or undetectable. No differences in the percentage of TL-2-, IL-4- and IFN-gamma-producing Th and T-suppressor/cytotoxic lymphocytes were found between neonates from atopic and non-atopic parents. These results will be re-evaluated when the atopic status of the children at the age of 1 and 2 years can be assessed.

Animals↗
PubMed2000

Influence of blood and synovial fluid immune complexes of patients with rheumatoid arthritis on production of nitric oxide and growth and viability of chondrocytes.

OBJECTIVE: To determine whether blood and synovial fluid (SF) immune complexes (IC) of patients with rheumatoid arthritis (RA) influence the production of nitric oxide (NO) and growth and viability of chondrocytes. METHODS: IC were precipitated and IgM and IgG were determined in the precipitates by ELISA and nephelometry, respectively. Primary cultures of bovine articular chondrocytes were incubated with the IC precipitates. After 48 h NO was determined as nitrite. After 7 days, growth was determined by incorporation of tritiated thymidine and viability was detected by neutral red uptake. RESULTS: Patient sera were positive in 8/12 for IgM IC and 9/12 for IgG IC, and 1/8 control sera was slightly positive for IgM IC. Seven of 12 SF samples were IgM IC and 10/12 IgG IC positive. With and without additional interleukin 1alpha (IL-1alpha) stimulation, NO production by chondrocytes was significantly higher with SF IC precipitates than with control serum precipitates (p = 0.03, p = 0.04, respectively). NO production by chondrocytes that were not stimulated with IL-1alpha was significantly increased with SF IC precipitates compared to RA serum IC precipitates (p = 0.03). SF IC significantly inhibited growth compared to control serum precipitates (p = 0.04) and RA serum IC (p = 0.012). Neutral red uptake by chondrocytes was significantly decreased when incubated with RA serum IC in comparison with control serum IC (p = 0.012) and SF IC (p = 0.006). With and without additional IL-1alpha stimulation, NO production by chondrocytes after incubation with SF derived IC was positively correlated to the Ritchie score (r = 0.8, r = 0.7, respectively) and the number of swollen joints (r = 0.8, r = 0.6, respectively). CONCLUSION: These results support the hypothesis that, especially in active RA, SF derived IC stimulate NO production and inhibit chondrocyte growth.

Antigen-Antibody Complex↗
PubMed1999

Flow cytometric detection of type 1 (IL-2, IFN-gamma) and type 2 (IL-4, IL-5) cytokines in T-helper and T-suppressor/cytotoxic cells in rheumatoid arthritis, allergic asthma and atopic dermatitis.

Type 1 cytokines (a.o. IL-2 and IFN-gamma) play an important role in the pathogenesis of rheumatoid arthritis. On the other hand, IgE-mediated diseases such as allergic asthma and atopic dermatitis show a type 2 cytokine (amongst others IL-4 and IL-5) profile. This study examined simultaneously the intracellular production of IL-2, IFN-gamma, IL-4 and IL-5 in T-lymphocytes of patients with rheumatoid arthritis during treatment with methotrexate or salazopyrin, patients with allergic asthma or atopic dermatitis under stable treatment, compared to healthy controls.A three-colour flow cytometric analysis was used for cytokine detection in T-helper cells and T-suppressor/cytotoxic cells. Compared to controls, patients with symptomatic atopic dermatitis showed an increased number of IL-4-producing T-helper lymphocytes in basal circumstances (P=0.001), in contrast to asymptomatic allergic asthma patients. Compared to controls, rheumatoid arthritis patients, treated with salazopyrin, showed an increased number of IL-2-producing T-helper and T-suppressor/cytotoxic lymphocytes after in vitro stimulation with PMA and ionomycin (P=0.01). In contrast, rheumatoid arthritis patients, treated with methotrexate, a more potent disease modifying drug, did not show this type 1 cytokine profile. A positive correlation was found between the number of IFN-gamma producing T-helper cells and disease activity (Ritchie Index and number of swollen joints) in both rheumatoid arthritis patient groups. Active atopic dermatitis patients showed a type 2 cytokine profile, whereas stable asthma patients with lower disease activity did not show a predominance of type 2 cytokines. Rheumatoid arthritis patients under treatment with salazopyrin had a type 1 cytokine profile, which could not be demonstrated in patients treated with methotrexate. This imbalance between type 1 and type 2 cytokines in different immune mediated disorders can be related with treatment and the grade of disease activity. These results stress the need for further investigation of the influence of therapy on cytokine profiles.

Adolescent↗
PubMed1999

Flow cytometrical determination of interleukin 1beta, interleukin 6 and tumour necrosis factor alpha in monocytes of rheumatoid arthritis patients; relation with parameters of osteoporosis.

Experimental data suggest that pro-inflammatory cytokines such as interleukin 1beta (IL-1beta), interleukin 6 (IL-6) and tumour necrosis factor alpha (TNF-alpha) are important in the pathogenesis of osteoporosis in rheumatoid arthritis. Therefore we compared the production of these cytokines by monocytes in 10 rheumatoid arthritis patients and 10 controls. Cytokine levels in rheumatoid arthritis patients were related to disease activity parameters, bone mineral density (BMD) corrected for age and sex (Z scores) and osteocalcin as a laboratory parameter of bone remodelling. Cytokines were determined by a flow cytometrical technique. There was a tendency for higher IL-1beta levels in patients compared with controls. A positive correlation between erythrocyte sedimentation rate and spontaneous production of monocytic cytokines was found. Z scores of the lumbar spine showed a negative correlation with spontaneous production of IL-1beta and IL-6. Plasma osteocalcin levels were positively correlated with spontaneous production of IL-1beta, IL-6 and TNF-alpha. In conclusion, the correlation of the levels of these cytokines with parameters of bone metabolism and osteoporosis suggest that especially IL-1beta and IL-6 are associated with more pronounced osteoporosis in active rheumatoid arthritis.

Absorptiometry, Photon↗
PubMed1999

Effects of suramin on anastomotic colon tumors in a rat model.

BACKGROUND: The development of antiangiogenic drugs offers new promise in the treatment of malignancy. Suramin has been reported to inhibit tumor growth by blocking angiogenesis and has been used in clinical trials. The aim of the present study was to examine the effects of suramin on colonic anastomotic tumors in the rat. METHODS: (a) Colonic anastomotic tumor was induced in 120 WAG/RIJ rats. Half of the animals were given 100 mg/kg of suramin intraperitoneally at the time of tumor induction. Rats were sacrificed after 2, 4 and 8 weeks; tumor take and tumor weight were evaluated. (b) The number of red blood cell clusters per x 400 field was counted in each tumor. (c) A lymphocyte transformation test was performed in four groups of animals, 2 weeks before and 2 weeks after tumor implantation and/or suramin administration. RESULTS: (a) A significant enhancement of tumor growth was observed in the suramin-treated animals. (b) This was accompanied by a significant increase in functional blood vessels. (c) Suramin-treated rats had markedly decreased lymphocyte stimulation, pointing to a possible immunosuppressive effect. CONCLUSIONS: The growth of an anastomotic colon tumor is rather enhanced by a single intraperitoneal administration of 100 mg/kg suramin in the rat, possibly by an unexpected immunosuppressive effect.

Adenocarcinoma↗