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Biomedical subjects

A Kijlstra

Publications and source records attributed to A Kijlstra.

At least 181 records · Page 10Linked to original sources
PubMed1989

Aqueous humor analysis as a diagnostic tool in toxoplasma uveitis.

Analysis of local toxoplasma antibody production to confirm a suspected clinical diagnosis of toxoplasma chorioretinitis is a valuable diagnostic tool. Determination of toxoplasma antibodies in the blood of the patient is of limited use. When blood toxoplasma tests are negative this indicates that toxoplasma as a causative organisms in the pathogenesis of uveitis is unlikely. A positive blood test is a sensitive test (100% patients positive) but not a specific test since so many healthy individuals already have undergone subclinical infection and have acquired humoral immunity against the parasite. We analysed 93 paired aqueous and serum samples for toxoplasma antibodies and total IgG and determined the Goldmann-Wittmer coefficient. In patients retrospectively diagnosed as having toxoplasma chorioretinitis 16 out of 22 had a positive coefficient, indicating local parasite antibody production. In one patient with AIDS we also found a positive toxoplasma coefficient. Three out of 15 patients with posterior uveitis of unknown origin also had a positive coefficient. None of the cataract patients tested (n = 32) had a positive coefficient. Major drawbacks of aqueous humor analysis are that a false negative antibody coefficient can occur when a massive blood aqueous barrier breakdown has occurred.

Antibodies, Protozoan↗
PubMed1989

The role of tears in preventing protein deposition on contact lenses.

Recently the presence of a coating inhibitory factor was described in human tears which can prevent the binding of proteins to a solid phase. In these earlier studies depositions of lactoferrin and IgG onto plastic was studied. In the study described here, peroxidase conjugated albumin was used as a model to investigate the effect of human tears on the binding of proteins to plastic surfaces. We investigated the question whether contact lens deposits are associated with decreased levels of this factor in the tearfilm of contact lens wearers. The mean value of the coating inhibiting activity in the tears of the controls did not differ significantly from contact lens wearers without deposits. The contact lens wearers with deposits on their lenses, had a lower mean coating inhibiting activity than the contact lens wearers without deposits. No significant difference was seen in coating inhibiting activity in tears obtained from individuals before and after they had worn lenses for three weeks. Also no difference was observed in the coating inhibiting activity on the eyes of persons who were wearing a lens in one eye only. The results of our study show that a too low activity of the coating inhibiting factor in tears is associated with deposits on contact lenses.

Adult↗
PubMed1989

Gel electrophoresis of human tears reveals various forms of tear lactoferrin.

Lactoferrin is a metal binding protein, which is present in high concentrations in human tears. Little is known concerning the exact molecular shape of lactoferrin in tears. Sodium dodecyl sulphate polyacrylamide gel electrophoresis (SDS-PAGE) and immunoblotting experiments showed that this protein is present in multiple forms in tear fluid. SDS-PAGE analysis of human tears under non reducing conditions and pretreatment of tears in sample buffer at room temperature revealed lactoferrin in a major form of 60 kD, a minor form of 64 kD and a third form of 52 kD. Pretreatment of tears at elevated temperatures prior to sample application resulted in the loss of this third form. Disruption of intrachain disulfide bridges prior to SDS-PAGE analysis resulted in a shift in the apparent molecular weight of lactoferrin to 78 kD and 83 kD for the major and minor form, respectively. Chromatography of human tears on ConA-Sepharose as well as enzymatic deglycosylation showed that the difference in molecular weight of the major and minor lactoferrin form was not due to a variation in the carbohydrate side chains. The presence of the minor form could also not be ascribed to iron saturation. Instead we found that addition of iron ions to human tears resulted in a shift of tear lactoferrin to a lower molecular weight species of about 52 kD, coinciding with the third lactoferrin form mentioned above and a small protein band of approximately 57 kD, representing the iron saturated minor lactoferrin form. Similar findings were observed using purified milk lactoferrin. Increasing the temperature prior to sample application or disruption of disulfide bridges dissociated the iron-lactoferrin complex.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1989

Antibodies against ocular and oral antigens in Behçet's disease associated with uveitis.

An indirect immunofluorescence test (IIF) using guinea pig lip as a substrate was performed with sera from 10 patients with Behçet's disease and the results were compared to IIF with sera of 16 patients with uveitis of Turkish origin, 62 patients with non- Behçet's uveitis, 9 patients with stomatitis aphtosa and 34 healthy controls. Antibodies to guinea pig lip cytoplasmic antigens were present in 70% of the Behçet patients, in 19% of uveitis patients of Turkish origin (P less than 0.05), in 12% of the non Behçet uveitis patients (P less than 0.001), in 11% of the stomatitis aphtosa patients (P less than 0.05) and in 9% of the healthy controls (P less than 0.001). A positive Behçet serum preincubated with the supernatant of guinea pig lip sections incubated in PBS gave an inhibition on the IIF test, indicating that the antigen involved in a soluble cytoplasmic substance. No significant increase in the presence of antibodies against iris, cornea or retina (mouse eye) were detected in the Behçet sera. Of interest was the finding of a positive reaction in 6 out of 10 patients in the episcleral region of the mouse eye. This positive reaction resembles immune complex like material. Our findings suggest that using the external surface of the guinea pig lip as a substrate is useful in selecting out those patients with Behçet's disease from uveitis patients with an unknown etiology and from patients with aphtous stomatitis.

Adult↗
PubMed1989

Immunoreactivity and cross-reactivity of human and bovine retinal S-antigen.

The reactions of human and bovine retinal S-antigen (S-ag) with polyclonal rabbit antibodies were compared in ELISA, immunoblotting and inhibition ELISA. Titrations in ELISA with plastic-adsorbed S-ags revealed that the great majority (70-100%) of human S-ag epitopes and anti-human S-ag antibodies were cross-reactive. In contrast, the cross-reactivity of bovine S-ag (25%) and anti-bovine S-ag antibodies (15-20%) indicated an important contribution of species-specific epitopes to the antigenicity of bovine S-ag. Immunoblotting of S-ag fragments after treatment with chymotrypsin confirmed these differences and also demonstrated different chymotrypsin-induced cleavage patterns of human and bovine S-ag. Thus, in assays involving partial denaturation and/or degradation of the antigens, human S-ag showed little, and bovine S-ag a marked species-specific immunoreactivity. In inhibition ELISA however, in which S-ags in solution could be studied, species-specific reactions strongly predominated for both S-ags. Anti-human S-ag and anti-bovine S-ag antibodies could be absorbed with nM concentrations of fluid phase human and bovine S-ag, respectively, whereas in both cases the cross-reacting antigen had no detectable inhibitory potential. The epitopic structures of human and bovine S-ag in solution may thus be largely different.

Animals↗
PubMed1989

Intraocular antibody synthesis during experimental uveitis.

Determination of intraocular antibody synthesis against certain microorganisms is a diagnostic aid in identifying the causative agent in clinical uveitis. Little is known, however, concerning the kinetics and specificity of antibodies produced during intraocular inflammation. To investigate this subject we induced uveitis in rabbits by injecting small amounts of human serum albumin (HSA) into the vitreous. Aqueous humor and serum were taken before and after the induction of uveitis and levels of total IgG, rabbit albumin and anti-HSA-IgG were determined. The anti-HSA-IgG was quantitated using immunoaffinity purified anti-HSA-IgG as a standard. Six weeks after intravitreal HSA injection, high levels of total IgG (4.7 mg/ml) and albumin (15.4 mg/ml) were observed in the aqueous as compared to control eyes (IgG: 0.12 mg/ml; albumin: 0.48 mg/ml). Using albumin to correct for blood aqueous barrier breakdown we calculated that only 0.6% of the locally synthesized IgG was directed against intravitreally injected HSA. Two months after the intravitreal injection of HSA the main signs of the uveitis had subsided. A recurrent uveitis was subsequently induced by an intravenous HSA injection. This resulted in a marked increase of total IgG (14.3 mg/ml) and albumin (24.6 mg/ml) in the aqueous humor of the uveitis eyes. It was remarkable that the mean anti-HSA-IgG level (0.62 mg/ml) in the uveitis eyes was higher than that seen in serum (0.41 mg/ml). After this secondary uveitis, 9% of the locally synthesized antibodies were directed against HSA.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1989

Immunity to a corneal antigen in Fuchs' heterochromic cyclitis patients.

Immunity to a major corneal antigen was studied in 28 Fuchs' heterochromic cyclitis patients and compared with the response of 44 patients with other types of uveitis and 19 healthy controls. The highest incidence of immune response was found in patients with anterior segment involvement only (anterior uveitis and Fuchs') whereas the frequency of anti-corneal immune response in patients with posterior segment involvement only was low and not significantly different from that of healthy controls. Cellular immunity to corneal antigens was found in the majority of Fuchs' heterochromic cyclitis patients, and in one-third of the anterior uveitis patients. No correlation could be established in these patients between a positive cellular response and the chronicity of the disease or the presence of keratic precipitates. Humoral immunity to the corneal antigen was also the highest in patients with anterior segment involvement, but there was no difference in response between Fuchs' and non-Fuchs' anterior uveitis patients. This study suggests that anti-corneal immunity may be triggered in inflammatory diseases of the anterior segment, especially in Fuchs' heterochromic cyclitis.

Adult↗
PubMed1988

Analysis of tear proteins in Graves' ophthalmopathy by high performance liquid chromatography.

Using high performance liquid chromatography, we analyzed tears from 50 patients with Graves' ophthalmopathy and 20 controls. With this technique, tear constituents are separated according to size; a normal tear protein profile consists of five peaks. An increase in one or more peaks was observed in 14 patients (28%) and in none of the controls. No decreased values were observed. No relation was observed between abnormalities of tear composition and the clinical NO SPECS classification. There was a tendency for increased tear protein peaks in those patients with long-standing disease. Most patients with an increase in one or more tear protein levels had normal thyroid function after treatment for hyperthyroidism. Our findings suggested that the inflammatory process in the orbit occurring in Graves' ophthalmopathy also had an effect on the lacrimal gland, which was reflected in the composition of the tears.

Adolescent↗
PubMed1988

Uveitis and diabetes mellitus.

Of 340 patients with anterior uveitis, 20 (6%) had diabetes mellitus. This is significantly higher than the prevalence of 1.4% in the normal Dutch population (P less than .001). Of 128 patients with idiopathic anterior uveitis, 16 (12.5%) had diabetes mellitus compared to only four (1.9%) of 212 patients with anterior uveitis with an established specific ocular diagnosis (P less than .001). Of the 16 diabetic patients with idiopathic anterior uveitis, ten (63%) had type I diabetes mellitus and 12 (75%) suffered from severe diabetic complications as angiopathy, nephropathy, and neuropathy. The onset of diabetes mellitus preceded the onset of anterior uveitis in all cases. Whether or not uveitis in diabetic patients is a true inflammation rather than an ischemic phenomenon is still unknown.

Diabetes Complications↗
PubMed1988

HLA typing in birdshot chorioretinopathy.

We examined 49 patients with birdshot chorioretinopathy in whom HLA typing had been performed. Of these 49 patients, 47 (95.9%) had the HLA-A29 antigen. The HLA-B12 (B44) antigen was also significantly associated with the disease, but this antigen is known to be in linkage disequilibrium with the antigen HLA-A29. The HLA-A2 antigen was less frequent in patients with birdshot chorioretinopathy than in the control group of normal European individuals (20% as compared to 44.6%).

Choroid↗
PubMed1988

High incidence of corneal epithelium antibodies in Fuch's heterochromic cyclitis.

Sera obtained from 26 patients with Fuchs' heterochromic cyclitis were examined for the presence of autoantibodies directed against the anterior segment of the eye by means of immunofluorescence techniques. Antibodies against human iris tissue could not be detected, whereas autoantibodies against corneal epithelium were found in almost 90% of cases. This is the first report describing the presence of autoantibodies in patients with Fuchs' heterochromic cyclitis and it provides a further clue that immunological mechanisms might play an important role in the aetiology of Fuchs' heterochromic cyclitis.

Adult↗
PubMed1988

Immunoreactive epitopes on human retinal S-antigen.

Although retinal S-antigen can induce experimental auto-immune uveitis in various animal species including primates, its role in clinical uveitis is not exactly known. More detailed knowledge on the immunoreactivity of human S-antigen might be of importance, since bovine S-antigen has been shown to carry both uveitogenic and non-uveitogenic epitopes. The number of immunoreactive epitopes on purified human S-antigen was therefore investigated in an inhibition ELISA with the use of a panel of four polyclonal and two monoclonal immune reagents. Assessment of their capacity to compete with each other for binding to the antigen resulted in complete, partial or no inhibition in the various combinations tested. Rabbit and rat anti-S-antigen immunoglobulins inhibited each other partially (up to 60%), from which the existence of at least three (groups of) epitopes was derived. Two monoclonal antibodies, of mouse (PDS-1) and rat (S.2.4C5) origin, did not inhibit each other, and thus defined two separate epitopes on human S-antigen. These epitopes belong to the set recognized by both rabbit and rat anti-S-antigen immunoglobulins since both monoclonals could be inhibited by rabbit and by rat antibodies. Epitopes detected by two mouse antisera also appeared to belong to this set. Thus, the existence of at least four immunoreactive sites on human S-antigen could be demonstrated.

Antibodies, Monoclonal↗
PubMed1988

Factors influencing the quantitative determination of tear proteins by high performance liquid chromatography.

HPLC analysis of human tears allows tear protein profiles to be obtained within ten minutes. A tear protein profile normally consists of 4 major peaks: IgA, lactoferrin, protein G and lysozyme. Although it is a rapid method, the use of High Performance Liquid Chromatography in the (quantitative) determination of proteins in tears is influenced by various factors. The day to day variability of the quantitative use, ranges between 7 and 9% for the various tear proteins. Combining the HPLC method with a convenient collection method such as sponges or Schirmer strips, showed that the sponges and some of the Schirmer strips used in this study eluted significant material absorbing light at 280 nm. No statistical difference was observed in the HPLC protein profiles of tears collected with Schirmer strips or with sponges. Using sponges has the advantage that they can absorb almost twice as much tears in a same period of time as Schirmer strips. HPLC analysis of human tear proteins is not accurate when there is albumin leakage as in traumatic sampling with Schirmer strips or in inflammatory states. The I-125 column which was used in our study is not able to separate lactoferrin and albumin, which may cause an overestimation of lactoferrin in inflammatory conditions. The study presented here indicates that for quantitative use of HPLC in epidemiological tear protein research better separating protein gel filtration columns are needed.

Adult↗
PubMed1988

In vivo and in vitro deposition of immunoglobulin aggregates in the mouse eye.

The possible role of specific mechanisms involved in the adherence process of immune aggregates to tissue components of the mouse eye was investigated in an experimental animal model. Passive intravenous administration of immunoglobulin aggregates to mice, resulted in the localisation of these aggregates in various organs, including the eye. In the eye a strong localisation was seen in the episcleral capillary plexus, whereas only a weak deposition was seen in the iris, ciliary body and choroid. No deposits were seen in the retina. To investigate the role of specific receptors for immune complexes in the eye, in vitro experiments were performed, whereby immunoglobulin aggregates were layered on cryostat sections of the mouse eye. These in vitro studies also showed an adherence of immune aggregates to the episcleral capillary region, but furthermore a deposition on mast cells scattered throughout the extra-ocular muscles. The in vitro binding of immunoglobulin aggregates to the episcleral capillary plexus could be inhibited by high concentrations of Fc fragments and monomeric IgG, but not with Fab fragments or 0.5 M NaCl. The in vitro adherence of aggregates to mast cells could not be blocked by the inhibitors employed in our study and could therefore be distinguished from the interaction of aggregates with the episcleral capillary plexus. These results indicate that the ocular deposition of immunoglobulin aggregates in the episcleral capillary plexus of the mouse eye is (immune) specific and mediated by Fc receptors.

Animals↗
PubMed1987

The predictive value of serum angiotensin converting enzyme and lysozyme levels in the diagnosis of ocular sarcoidosis.

We determined the serum angiotensin converting enzyme and lysozyme levels in 221 patients with uveitis and in 67 control subjects. Angiotensin converting enzyme and lysozyme levels were found to be age dependent. Of the 221 patients, 12 had sarcoidosis. In patients with uveitis who had an angiotensin converting enzyme level above 50 units/l (mean + 2 S.D.), the sensitivity of the test was 84%, the specificity was 95%, and the predictive value was 47%. In these same patients the sensitivity was 60% for a lysozyme level above 8 mg/l (mean + 2 S.D.), the specificity was 76%, and the predictive value was 12%.

Adult↗
PubMed1987

Clinical features of acute anterior uveitis.

We studied the clinical features and prognosis of 73 patients with HLA-B27 positive and 71 patients with HLA-B27 negative acute anterior uveitis using computer analysis of more than 50 variables per patient. The patients with HLA-B27 positive acute anterior uveitis showed the following characteristics which were significantly different from patients with HLA-B27 negative acute anterior uveitis: younger age at onset; high male to female ratio; frequent unilateral alternating eye involvement; severe ocular symptoms during activity, such as presence of fibrin in the anterior chamber; absence of mutton fat keratic precipitates; high incidence of ocular complications; and frequent association with seronegative spondyloarthropathies. Despite the difference of disease severity and incidence of complications, the long-term visual outcome did not differ significantly between the two groups. No distinctions were observed when patients with HLA-B27 positive acute anterior uveitis were subdivided according to sex or the presence of ankylosing spondylitis. HLA-B27 positive acute anterior uveitis formed a distinct clinical entity associated with serious prognosis as compared to HLA-B27 negative acute anterior uveitis.

Acute Disease↗
PubMed1987

The effect of lactoferrin on complement mediated modulation of immune complex size.

Earlier we showed that human lactoferrin is capable of inhibiting the complement-mediated lysis of antibody-coated erythrocytes due to an inhibition of the formation of the classical C3 convertase. In this report the effect of lactoferrin on complement mediated modulation of immune complex size was studied. Lactoferrin was shown to inhibit the complement-dependent solubilization of immune precipitates with kinetics resembling that seen by others using C2 deficient serum. Lactoferrin, however, did not affect the complement-dependent inhibition of immune precipitation. These findings confirm our earlier observations that lactoferrin has no effect on the activation of the very early complement components (C1 and C4), but inhibits C3 deposition on immune complexes which is a crucial mechanism in immune precipitate solubilization.

Animals↗