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Biomedical subjects

W J Stevens

Publications and source records attributed to W J Stevens.

At least 73 records · Page 4Linked to original sources
PubMed1995

Dinitrobenzene induces methemoglobin formation from deoxyhemoglobin in vitro.

The reaction of hemoglobin (Hb) with dinitrobenzenes (DNBs) was studied to develop a molecular-level understanding of such reactions that will enhance the development of toxicokinetic models that employ Hb adducts as biomarkers for exposure. Methemoglobin (metHb) is formed during the reaction and UV/VIS spectroscopy was used to follow the reaction of DNB isomers with deoxy-(dxHb), oxy-(HbO2) and carboncarboxy-(HbCO) hemoglobin. HPLC chromatography of dxHb treated with radiolabelled DNB was employed to detect possible adduct formation. Deconvolution of the spectra and the presence of well-defined isobestic points imply that DNB induces a direct conversion of dxHb to metHb, but little or no conversion occurs for either HbCO or HbO2. This implies that the reaction of DNB with Hb may require direct access to the heme and/or that the reaction is initiated by oxidation of the heme, which occurs more readily in the deoxy state. Labelled DNB formed no detectable covalent Hb adducts in the presence of dxHb, providing evidence that metHb formation is not linked to adduct formation.

Animals↗
PubMed1995

Specific decrease of anti-pseudomonal IgA after anti-pseudomonal therapy in cystic fibrosis.

UNLABELLED: In patients with cystic fibrosis (CF) and chronic colonisation with Pseudomonas aeruginosa, specific anti-pseudomonal IgG and IgA, as well as serum immunoreactive protein C, WBC and differential count, ESR, pulmonary function and chest radiograph score were determined before and after a 2 week intravenous course of anti-pseudomonal antibiotics in 32 cases of acute exacerbation of pulmonary infection. Specific anti-pseudomonal IgA but not specific anti-pseudomonal IgG decreased significantly after treatment. Log of anti-pseudomonal IgA but not log anti-pseudomonal IgG correlated well with disease severity as assessed by the Brasfield chest radiograph score (r 0.57), forced expiratory volume in 1 s (r 0.6) as well as C-reactive protein (r 0.62). CONCLUSION: Specific anti-pseudomonal IgA may be a better parameter than specific IgG in the follow up of lung infection in patients with CF, probably because it more closely reflects ongoing endobronchial infection, the major pathology in CF lungs.

Antibodies, Bacterial↗
PubMed1995

Expression of neutrophil activation markers and neutrophil adhesion to chondrocytes in rheumatoid arthritis patients: relationship with disease activity.

Neutrophil infiltration in synovial fluid is an important step in inflammation characterizing rheumatoid arthritis (RA). In this study, the activation and functional state of neutrophils in the blood and synovial fluid of patients with rheumatoid arthritis were compared: mean density of neutrophil activation markers CD11b, CD18 and L-selectin was measured with a flow cytometer, and adhesion to chondrocytes using a fluorimetric assay. No significant differences between control and patient peripheral blood neutrophils were observed. When comparing neutrophils of patient peripheral blood with paired synovial fluid, an increase in CD11b (p = 0.008) and a decrease in L-selectin (p = 0.008) were measured. For neutrophils of control and patient peripheral blood, fMet-Leu-Phe stimulation induced upregulation of CD11b (resp p = 0.007 and p = 0.008) and CD18 (resp p = 0.005 and p = 0.01). In the synovial fluid, no significant increase in CD11b and CD18 could be induced with fMet-Leu-Phe. Percentages of adherent neutrophils were comparable between controls and patients, both in peripheral blood and synovial fluid. Adhesion to chondrocytes of peripheral blood neutrophils of patients was correlated with clinical (Ritchie) and biological (erythrocyte sedimentation rate) parameters (resp r = 0.67, r = 0.73). In conclusion, these results demonstrate that peripheral blood neutrophil adhesion to chondrocytes was correlated with active disease, and that synovial fluid neutrophils were activated in vivo. These findings provide further evidence for the contributing role of neutrophils in articular destruction in RA.

Adult↗
PubMed1995

Latex anaphylaxis.

In the past decade, immediate hypersensitivity to latex has been accepted as a serious problem. The proteins that are present in natural rubber are considered to be the responsible antigens, and the hypersensitivity responses induced include contact and generalized urticaria, angioedema, rhinitis, conjunctivitis, bronchospasm, life threatening anaphylaxis and death. So far, children with spina bifida or severe urogenital defects, health care workers, and rubber industry employees appear to be at greater risk than the general population. Since 1991 several reports and cross-reactivity studies have demonstrated an association between latex allergy and allergy to certain fruits, especially banana, avocado and kiwi. Because our knowledge of the major allergens is still incomplete, standardised in vitro and in vivo tests are not yet readily available. Therefore, the clinician should rely on a medical history, physical examination, and reliable serological tests to confirm diagnosis of latex anaphylaxis. Because of possible systemic reactions to skin prick testing and provocation tests, these methods should be restricted to patients with a compelling history and an inconclusive serologic test result. Preventive measures are the key to successful and safe management of patients with latex anaphylaxis.

Adult↗
PubMed1995

The clinical manifestations of ochronosis: a review.

Ochronosis is a rare disease caused by an inherited lack of homogentisic acid oxidase. Alkaptonuria is the presence of homogentisic acid in urine. Ochronosis is characterized by the deposition of a dark pigment in tissues rich in collagen. A wide spectrum of clinical manifestations is described. The most important signs are ochronotic arthropathy, ocular and cutaneous pigmentation, genitourinary tract obstruction by ochronotic calculi and cardiovascular ochronosis, especially calcification and stenosis of the aortic valve. The constellation of these clinical signs should suggest the diagnosis which is confirmed by the detection of homogentisic acid in urine. There is no cure for the disease and treatment is based on symptomatic measures.

Cardiovascular Diseases↗
PubMed1994

Use of fluorescent dyes in the determination of adherence of human leucocytes to endothelial cells and the effect of fluorochromes on cellular function.

A number of supravital fluorochromes are available to study leucocyte functions in vitro and in vivo. The fluorescein ester most widely used, fluorescein diacetate, has the disadvantage of rapid cellular efflux, whereas more recently developed fluorescent probes do not exhibit this inconvenient trait. However, their effect on cellular functions has not been thoroughly investigated in humans. In this study, we describe a simple and rapid fluorometric method for measuring cell adhesion to endothelium, comparing 5 different fluorochromes. Furthermore, we evaluated the effect of fluorescent dye labelling (with CFDA, CFSE, BCECF-AM, calcein-AM or DiI), on various cell functions, including, apart from adhesion, lymphocyte proliferation, granulocyte chemotaxis and superoxide production. calcein-AM and DiI proved to be the fluorochromes with the least effect on cellular function. BCECF-AM did not interfere with lymphocyte proliferation, but exhibited some influence on superoxide production and chemotaxis of granulocytes. CFDA showed a detrimental effect on both lymphocyte and granulocyte functions whereas CFSE gave intermediate results. In the adhesion assay, calcein-AM, CFSE and DiI performed comparably well. Since labelling with C12-DiI was homogeneous, this probe was also appropriate for the adhesion test, although somewhat higher background staining was present. We conclude that the fluorochromes are powerful tools when analysing the adhesion of human leucocytes to endothelial cells. However, since fluorochrome labelling can interfere with other cellular functions, the fluorescent probe has to be carefully chosen with regard to the cell type and function to be studied.

Carbocyanines↗
PubMed1994

Lymphocyte activation status, expression of adhesion molecules and adhesion to human endothelium in rheumatoid arthritis--relationship to disease activity.

The synovial tissue of patients with rheumatoid arthritis (RA) is characterized by infiltration with inflammatory cells, mainly memory helper cells (CD4+CD29+). An important initiating step in tissue infiltration is the adhesion of peripheral blood lymphocytes to the vascular endothelium. Therefore, we studied lymphocyte-endothelium adhesion in 40 RA patients and in 19 controls by a sensitive fluorimetric assay, using human umbilical vascular endothelial cells. Furthermore, expression of adhesion molecules VLA (CD29) and LFA-1 (CD11a) on CD4+ and CD8+ T cells was determined. In order to evaluate the activation state of lymphocytes, the soluble interleukin-2 receptor (sIL2R) was measured. The relationship to disease activity was evaluated using the Ritchie articular index. RA patients had a higher percentage of CD4+ cells (p < 0.005) and a lower percentage of CD8+ cells (p < 0.001) than controls did. The CD4+CD29+/CD4+CD29- ratio and the CD8+CD29+/CD8+CD29- ratio were increased in patients with active RA (p < 0.01 and p < 0.05, respectively) and in patients with inactive disease (p = 0.09 and p < 0.005, respectively) compared with controls. LFA-1 (CD11a) was present on almost all T lymphocytes and its density did not differ between patients and controls. Serum levels of sIL2R were significantly higher in both patient groups compared with controls (p < 0.0005); patients with active disease showed significantly higher levels than patients with inactive disease (p < 0.05). Lymphocyte-endothelium adhesion was not increased in patients, although the expression of the adhesion molecule CD29 on T lymphocytes of RA patients was higher.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1994

Influence of hyposensitization on soluble interleukin-2 receptor, eosinophil cationic protein, in vitro lymphocyte proliferation, in vitro lymphocyte adhesion, and lymphocyte membrane markers in childhood asthma.

Soluble interleukin-2 receptor (sIL-2R), eosinophil cationic protein (ECP), the lymphoproliferative response to house-dust mite (HDM), adhesion to human umbilical vein endothelial cells (HUVEC), and lymphocyte membrane markers were studied in three groups of children: healthy children, asthmatic children without hyposensitization (HS), and asthmatic children with HS. HS was associated with significantly lower numbers of peripheral blood eosinophils (PBE) and lower sIL-2R serum levels and with a tendency to lower ECP serum levels and lymphoproliferative response to HDM. There were no changes in the T-lymphocyte phenotypic markers CD4 and CD8 among the three groups. The interleukin-2 receptor (IL-2R, CD25) on HDM-stimulated T lymphocytes increased over unstimulated T lymphocytes in the three groups. The CD25 expression was higher on HDM-stimulated lymphocytes in both asthmatic groups than in healthy children. Adhesion of lymphocytes on HUVEC increased significantly after HDM stimulation in asthmatic children without HS, whereas no change was observed in the two other groups. However, there was no change in the expression of adhesion molecules CD29 and CD11a on lymphocytes in either of the groups. This study provides further evidence that HS can modify lymphocyte and eosinophil functions.

Adolescent↗
PubMed1993

Interstitial lung disease and adult-onset Still's disease.

Adult-onset Still's disease is an uncommon rheumatological syndrome with a diversity of signs and symptoms. Pulmonary manifestations described are pleuritis and usually transient radiologic infiltrations. The patient presented in this case report had biopsy-proven lung fibrosis when adult-onset Still's disease was diagnosed. Three years after diagnosis, the patient developed clinical signs of the interstitial lung disorder. Radiological and histological progression was observed. Other causes of interstitial lung disorders were excluded. Clinicians should be aware that interstitial lung disease can be a complication of adult-onset Still's disease and can compromise the clinical status of the patient.

Adult↗
PubMed1993

Significantly increased expression of T-cell activation markers (interleukin-2 and HLA-DR) in depression: further evidence for an inflammatory process during that illness.

1. Recently, the authors have reported that severe depression may be accompanied by a systemic immune activation with an increase in the number of T cells expressing activation receptors. 2. The present large-scale study examines specific T (CD2+HLADR+ and CD7+CD25+) and B (CD7-CD25+) cell activation markers in depressed inpatients and normal volunteers together with the number of leukocytes and monocytes. 3. The authors have established that depression is characterized by a significantly increased expression of T cell activation receptors (CD7+CD25+) and by the appearance of previously unexpressed T cell surface markers (CD2+HLADR+). There was a significant and positive correlation between the number of CD7+CD25+ cells and monocytes, with the expression of the HLADR and CD25 T cell activation markers being significantly and positively correlated. Up to 64% of all depressed subjects exhibit an increased expression of these activation markers with a specificity of 91%. 4. The normal control group and the depressive sample constitute two discrete classes (i.e., qualitatively distinct groups) with respect to the expression of these activation markers and leukocytosis. 5. It is concluded that our results are compatible with the presence of T-cell activation in a considerable number of depressed patients.

Adult↗
PubMed1993

Study of eosinophil-endothelial adhesion, production of oxygen radicals and release of eosinophil cationic protein by peripheral blood eosinophils of patients with rheumatoid arthritis.

Beside lymphocytes and neutrophils, eosinophils are also involved in the inflammatory reaction in rheumatoid arthritis (RA). In this study, adhesion characteristics of peripheral blood eosinophils were studied in 43 RA patients and 19 controls, together with the expression of the beta2-integrin Mac-1 (CD11b/CD18). In addition, the production of oxygen radicals of isolated peripheral blood eosinophils and serum levels of eosinophil cationic protein (ECP) were measured in order to evaluate eosinophil activation. Adhesion of eosinophils to unstimulated human vascular endothelium was significantly higher in RA patients with active disease (n = 4) compared with controls (n = 14) (P < 0.005) and compared with patients with less active RA (n = 16) (P < 0.05). Nevertheless, the expression of the adhesion molecule Mac-1 (CD11b/CD18) was not increased in RA patients. ECP levels were higher in RA patients with active disease (P < 0.01). Release of oxygen radicals in response to phorbol stimulation was significantly elevated in active RA compared with controls (P < 0.05) and to less active RA (P < 0.05). We conclude that eosinophils of RA patients, especially those with active disease, are activated or at least primed and are involved in the inflammatory process in RA, analogous to the inflammation in asthma. The higher adhesion to inflamed endothelium is indicative of a higher infiltration in the joints, where tissue damage can be caused by toxic oxygen radicals and by granular proteins, such as ECP.

Adult↗
PubMed1993

Lymphocyte transformation test with house dust mite (Dermatophagoides pteronyssinus) in normal children, asthmatic children and asthmatic children receiving hyposensitization.

In the first part of this study the proliferative response of lymphocytes (lymphocyte transformation test) to house dust mite (HDM) stimulation in cultures was studied in normal children (n = 16), asthmatic children who never received hyposensitization (HS) (n = 50) and asthmatic children receiving HS with HDM for at least 6 months (n = 20). The results are expressed as disintegrations per minute (d.p.m.) and as stimulation index (SI = d.p.m. in the presence of the allergen/d.p.m. in the control culture). A positive SI (> 2) was found in 54% of the asthmatic children who never received HS, in 30% of the asthmatics receiving HS and in none of the normal children. Furthermore, between asthmatics with and without HS, the SI was not statistically different, although asthmatics without HS tended to have a higher SI (median value: 2.13 vs 1.38) (P = 0.10). In a second series of experiments the effect of adding interleukin-2 (IL-2) to the lymphocyte cell culture was studied in asthmatic children with and without HS. Interleukin-2 induced an additional stimulatory effect on the lymphoproliferative response to HDM and to phytohaemagglutinin in patients who never received HS, but had no effect in patients receiving HS. We conclude that HS treatment seems to have an inhibiting effect upon this proliferative response, not only inhibiting the degree of the allergen-induced lymphocyte proliferation, but also inhibiting the sensitivity of proliferating lymphocytes for IL-2. These inhibiting effects upon lymphocytic activation could be responsible for the anti-inflammatory effects (i.e. suppression of the late asthmatic reaction) of HS.

Allergens↗
PubMed1993

Effect of a bronchial provocation test with house-dust mite on blood eosinophilia, eosinophil cationic protein, soluble interleukin-2 receptor, and interleukin-6 in asthmatic children.

Eighteen children with perennial asthma and allergy to house-dust mite (HDM) underwent a bronchial challenge with HDM. Before and 24 h after the test, a venous blood sample was taken to determine levels of eosinophils, eosinophil cationic protein (ECP), soluble interleukin-2 receptor (IL-2R), and interleukin-6 (IL-6). A histamine challenge was performed before and 24 h after the HDM challenge. All subjects showed an immediate asthmatic reaction (IAR). A definite late asthmatic reaction (LAR) was observed in 15 children, a probable LAR in two, and no LAR in one. Because of persistent bronchial obstruction (FEV1 < 70%), eight children were unable to perform a histamine challenge 24 h after the allergen challenge. These were the children with the lowest prechallenge provocation dose (PD20) of histamine. In the other 10 children, the mean PD20 histamine decreased after the HDM challenge (mean PD20 before was 0.56 mg/ml; after challenge it was 0.14 mg/ml; P = 0.007). After the HDM challenge, an increase was detected in the mean values of blood eosinophils (mean before was 446/mm3; mean after was 733/mm3; P = 0.002), ECP (mean before was 26.3 micrograms/l; mean after was 34.3 micrograms/l; P < 0.040), and IL-2R (mean before was 116.35 U/ml; mean after was 128.52 U/ml; P < 0.040). On the other hand, IL-6 remained unchanged after the HDM challenge (mean before was 9.47 pg/l; mean after was 9.70 pg/l; P = 0.360).(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
PubMed1993

Are hypodense eosinophils in children activated or immature?

In patients with allergic asthma and rhinitis high numbers of hypodense eosinophils (HE) have been demonstrated. In a previous study we reported that asthmatic and healthy children had more HE than their adult counterparts. We assumed that this might, in part, be due to the presence of immature eosinophils in children. To distinguish between immature and activated eosinophils, determination of eosinophil cationic protein (ECP) might be interesting as it is known that high serum levels of ECP are associated with increased activation of eosinophils. In this study we determined the levels of ECP in serum in asthmatic and healthy children and adults trying to distinguish activated from immature eosinophils. We found that ECP levels were not increased in children (healthy and asthmatic) compared to adults (healthy and asthmatic). This supports the hypothesis that increased numbers of HE in childhood are, at least in part, immature eosinophils. Nevertheless, we could confirm that inflammation was present in children because soluble interleukin-2-receptor (sIL-2R), a marker of lymphocyte activation, was higher in asthmatic children as compared to healthy children. IL-6, a marker of macrophage/monocyte activation, was not different in the different patient groups. We conclude that although signs of inflammation are present in childhood asthma, the increased numbers of HE in children are in part due to the presence of immature eosinophils.

Adult↗
PubMed1992

Detection of hypodense eosinophils by Percoll multilayer density gradient centrifugation in subjects with normal or slightly elevated eosinophilia. Poor reproducibility and eosinophils of density < 1.077 g/ml.

In patients with marked hypereosinophilia 'hypodense' and 'normodense' eosinophils have been found after density gradient centrifugation. Subsequently this terminology has also been used in studies of patients with milder eosinophilia. However, in these cases the differentiation between normo- and hypodense eosinophils was less clear. This might be due to the high imprecision of the test of density gradient centrifugation, as demonstrated in the first part of this study: the mean within-assay variance of the number of eosinophils in the different density layers was 35%. It was calculated that the test must be performed eight times to obtain an estimate of the true mean for the individual patient. In the second part of the study, the absolute number of 'hypodense eosinophils' in groups of patients with asthma (adults and children) and rheumatoid arthritis (adults) were compared to normal controls. Although a difference in the absolute number of hypodense eosinophils between groups of patients and controls could be demonstrated, the high imprecision of the test of density gradient centrifugation suggested that the technique used was not useful in an individual with normal or slightly elevated eosinophils in the peripheral blood.

Adult↗
PubMed1992

Leukocytosis, monocytosis and neutrophilia: hallmarks of severe depression.

To date, there has been a small number of reports that severe depression is accompanied by disturbances in total white blood cell (i.e. leukocytosis) and leukocyte subset (i.e. neutrophilia, monocytosis, lymphopenia) counts. These results, however, have not yet been validated in a large-scale, well-controlled study. To this end, we have counted the number of leukocytes, monocytes, lymphocytes and granulocytes (neutrophils, eosinophils, basophils) in 22 healthy controls and in 109 depressed inpatients. We noted leukocytosis in major depressed patients compared with normal subjects, whilst minor depressives manifested intermediate findings. Leukocytosis was significantly more pronounced in major depressed males compared with major depressed females. Major depression related leukocytosis appears to be characterized by neutrophilia and monocytosis. There was a significant positive relationship between the overall severity of illness on one hand, and the degrees of leukocytosis, neutrophilia and monocytosis on the other. The total number of both phagocytic cell populations (i.e. monocytes and neutrophils) was significantly and positively related. Our results might point to the existence of an inflammatory process in major depressed subjects, particularly in males.

Adult↗