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Biomedical subjects

R Urbanek

Publications and source records attributed to R Urbanek.

At least 109 records · Page 6Linked to original sources
PubMed1987

[Embryofetopathy caused by postnatally detected maternal phenylketonuria].

A case of a now 10-month-old female infant is reported, who presented at birth with microcephalus, growth retardation, dystrophia, facial dysplasia and cardiac defect. Etiologically a classical phenylketonuria of the mother with very high levels of serum phenylalanine (51 and 41 mg/dl, respectively), which was not known until then, was diagnosed already after her confinement. The mother, aged 26, originates from Roumania. She had never been treated by any phenylalanine-limited diet. Psychological testing revealed a severely reduced intelligence (IQ = 63). The child, having normal levels of serum phenylalanine, presented with mild statomotor retardation at the age of ten months. Even in countries with a general neonatal screening program, a hitherto undiagnosed maternal phenylketonuria has to be considered within the differential diagnosis of a dystrophic microcephalic newborn, beside more common causes like the fetal alcohol syndrome.

Adult↗
PubMed1987

[Formation of specific IgG antibodies in l-asparaginase treatment. Distribution of IgG subclasses].

During l-Asparaginase (l-Asp) treatment the development of specific antibodies of IgG isotype is frequently observed. In most instances elevated IgG antibodies to l-Asp activate the complement system and induce allergic reactions following l-Asp infusion. However, in some cases no adverse reactions and no activation of complement are noticed, despite the presence of elevated anti-l-Asp levels. We studied the development of specific IgG antibodies to l-Asp in different subclasses in 12 children who had produced high levels of specific IgG. Results showed that all patients had elevated levels of IgG1. In 5 cases we were able to demonstrate the development of specific IgG3 antibodies and in 1 case of IgG4 antibody. Patients with high levels of IgG3 (above 100 AU) had the highest risk for subsequent anaphylaxis. Thus, subclass-specific determination of antibodies to l-Asparaginase might improve the estimation of the risk of anaphylaxis prior to 1-Asp infusions.

Adolescent↗
PubMed1987

Serological screening for allergy to inhalants by multi-allergen-radioimmunoassay.

201 children with inhalant allergy were examined with a new serological screening test ("Multi-Allergen-Test"). The sensitivity (95.1%) and specificity (91.9%) of the test were determined by comparing it to a "clinical classification", including results of history, physical examination, skin test and investigation for specific IgE antibodies. This yielded a diagnostic efficiency of 93.5%. A subsequent comparison of these results with the classification of patients by age-related total IgE levels showed the superiority of the "Multi-Allergen-Test" as far as screening for inhalant allergies is concerned. Additionally, the results for the specificity of the test were reproduced by examining another 18 children with food allergy, who had elevated total IgE levels but no inhalant allergic symptoms. The "Multi-Allergen-Test" proved to be a suitable screening procedure for inhalant allergy.

Allergens↗
PubMed1986

The use of monoclonal and polyspecific antibodies in the IgE sandwich ELISA.

The use of antibody to link antigen to microtitre plates in the enzyme-linked immunosorbent assay (ELISA) has been extended to include mouse monoclonal antibodies and polyspecific rabbit antibodies. Small amounts of both reagents could be used. The capacity of the microtitre plate for the antibody was found to be critical and irradiated plates generally gave better results. Both rabbit anti-IgE conjugated to horseradish peroxidase, and monoclonal mouse anti-IgE with alkaline phosphatase-conjugated rabbit anti-mouse IgG could be used as detection reagents. Comparison with the radioallergosorbent (RAST) test showed a good agreement with the sandwich ELISA. The sandwich ELISA using polyspecific rabbit antibody was substantially more sensitive than conventional ELISA and also marginally more sensitive than RAST.

Allergens↗
PubMed1986

Sub-class of IgG anti-bee venom antibody produced during bee venom immunotherapy and its relationship to long-term protection from bee stings and following termination of venom immunotherapy.

The IgG sub-class antibody response to bee venom in the four sub-classes was investigated in ten patients during and after venom immunotherapy. All patients tolerated a bee sting challenge 1, 2 and 3 years after the start of treatment as well as 1 and 2 years after treatment was stopped. Anti-phospholipase A2 (PLA2) antibodies were of IgG1 and IgG4 sub-class and rose early in treatment, IgG1 anti-PLA2 fell to pre-treatment levels after 3 years in contrast to IgG4 anti-PLA2 levels, which remained high during maintenance therapy and declined relatively little in the 2 years after the termination of treatment. This data shows that IgG4 antibodies are maintained in the absence of monthly maintenance injections and suggests that they may provide long lasting clinical protection from insect stings.

Adolescent↗
PubMed1986

Histamine release from peripheral blood leucocytes in egg-allergic patients.

Twelve egg-allergic patients were selected on the basis of a clinical history of egg allergy and a positive skin-prick test (SPT) to whole egg. A study was then carried out on the ability of the patients' washed leucocytes to release histamine in the presence of whole egg, ovomucoid, ovalbumin and ovotransferrin. Histamine release (HR) from washed leucocytes was demonstrated in ten out of twelve patients, but only four out of ten released over 40% of their total histamine. Spontaneous HR ranged from 2.1-14.5% with a mean of 7.5%. There was good agreement between positive and negative HR, skin test and radioallergosorbent test (RAST) results. Concordance between the HR and skin test was found in 83%, HR and RAST in 71% and skin test and RAST in 78% of patients. However there was poor quantitative agreement between these three tests. When skin-prick tests and HR thresholds were compared, ovomucoid elicited the greatest skin test sensitivity in five out of six patients, whereas five of the same six were more sensitive to ovalbumin when judged by HR.

Adolescent↗
PubMed1986

Sub-class of IgG in allergic disease. I. IgG sub-class antibodies in immediate and non-immediate food allergy.

Previous studies have suggested that, apart from IgE-mediated reactions, some of the symptoms of food allergy may be caused by IgG antibodies to food proteins. This study was carried out to see if there were any distinctive features of the IgG sub-class antibody response to dietary antigens which occurs in food allergic patients. IgG sub-class antibodies were measured using a quantitative enzyme-linked immuno-sorbent assay (ELISA) to wheat gliadin, ovalbumin and bovine casein in twenty patients who had coeliac disease and in twenty-eight egg allergic patients. These were compared with twenty-one atopic dermatitis patients who did not have food allergy and twenty-six healthy control subjects. Coeliac disease patients tended to have raised IgG antibody levels (especially IgG1) to all three antigens but these overlapped considerably with that seen in egg allergic and atopic dermatitis patients. Coeliacs who avoided gluten had anti-gliadin antibody levels which did not differ from those seen in healthy subjects but nevertheless had raised anti-ovalbumin and casein-specific antibodies. The IgG antibody was largely restricted to IgG1 and IgG4 sub-class although the relative amount of each varied with the antigen. Although gliadin-specific antibodies were mainly IgG1, ovalbumin-specific antibodies were mainly IgG4. The increased antibody levels to all three antigens in coeliacs were caused by a raised IgG1 response, IgG4 antibodies were usually normal. Egg allergic patients also had raised IgG1 but not IgG4 antibodies to ovalbumin. These data show that the response to different dietary antigens can vary with the antigen. The fact that IgG1 and not IgG4 antibodies were raised to all three antigens in patients with coeliac disease suggests that they are a secondary consequence of the disease, perhaps reflecting increased transport of antigens across a damaged gut mucosa rather than a specific immunopathological reaction. However, the observation that antibodies to gliadin, and not ovalbumin or casein, fell following gluten avoidance shows that the response to gliadin, at least, is dependent upon continued exposure to antigen.

Adult↗
PubMed1986

[The key role of IgG4 subclass antibodies in the development of protection against allergic reactions to insect stings].

Allergen immunotherapy results in protection against allergen challenge and in the production of allergen specific antibodies. We investigated the reaction to bee sting exposure and its relationship to the subclass of IgG-antibodies produced. 23 patients who had a history of systemic allergic reactions to bee stings were given 2-5 years courses of venom immunotherapy. 19 individuals tolerated a sting challenge 1, 2, and 3 years after the start of treatment, and after immunotherapy was discontinued. Four patients with persisting systemic reactions and 6 bee keepers served as controls. All detectable IgG-antibodies were restricted to subclass 1 and 4. In successfully treated patients the mean rise of IgG-subclass was 273%, and of IgG4 703%, compared to pretreatment levels. IgG4-antibodies were maintained at high levels in protected individuals when immunotherapy was discontinued. On the contrary, in non-protected individuals low IgG4-levels were observed. Specific IgG4-antibodies most closely reflect clinical protection from stings provided by immunotherapy or a repeated antigenic stimulation.

Adolescent↗
PubMed1986

[Diagnostic procedures in abnormal reactions to foods and food additives].

Allergic and intolerance reactions to food and food additives may occur as a result of antibody-mediated or non-immunological mechanisms. Histories of adverse reactions to food must be confirmed and clarified by means of in-vivo and in-vitro tests. Offending substances and clinical manifestations are enumerated. The predictive value and the diagnostic or the threshold sensitivity in provocation tests are demonstrated. There are useful laboratory techniques as the detection of specific antibodies or the estimation of involved mediators. Further procedures for the identification and confirmation of the diagnosis of adverse reactions to food and food additives are suggested.

Allergens↗
PubMed1985

Use of the enzyme-linked immunosorbent assay for measurement of allergen-specific antibodies.

A sensitive and specific enzyme-linked immunosorbent assay (ELISA) for allergen-specific IgG antibodies is described. Various solid-phase supports (microtiter plates), coating procedures, binding kinetics, and presentation of allergen in the assay were investigated. Using optimal conditions the indirect ELISA, in which the allergen is coated onto the well, was capable of detecting 2.4 ng/ml specific IgG antibodies to bee venom phospholipase A2(PLA2). The sandwich ELISA, in which the allergen was immobilized via specific antibody precoated onto the well, detected 0.24 ng/ml IgG antibodies to PLA2.

Antibodies, Anti-Idiotypic↗
PubMed1985

Increased sensitivity and specificity of a sandwich ELISA for measurement of IgE antibodies.

We have developed a sandwich enzyme-linked immunosorbent assay (ELISA) for measurement of IgE antibodies to the bee venom allergens phospholipase A2 (PLA2) and hyaluronidase (HYAL). The assay is 10-20 times more sensitive than conventional indirect ELISA or radioallergosorbent test (RAST). Furthermore, by using affinity purified rabbit antibodies to these allergens, the specificity of the test was increased compared to RAST. The use of antibodies to link the antigen to the solid phase removes the dependence on the individual protein's ability to bind to the microtitre plate. The increased sensitivity of the sandwich assay seems to be due to better presentation and retention of antigen on the solid phase.

Antibody Specificity↗
PubMed1985

Discontinuation of bee venom immunotherapy in children and adolescents.

Sixty-six patients with a history of systemic allergy reactions to bee stings, positive skin prick test to less than or equal to 100 micrograms/ml bee venom, and positive radioallergosorbent test (RAST) results were given venom immunotherapy. IgE and IgG antibodies to bee venom were measured by RAST and enzyme-linked immunosorbent test (ELISA), respectively. IgE and IgG anti-bee venom levels rose initially, but subsequently fell during immunotherapy. In 31 patients in whom specific IgE fell to low (less than 6% counts bound) or unmeasurable levels, immunotherapy was discontinued, and sting challenge was carried out 1 to 3 years later. All patients tolerated sting challenge well. The specific IgE and IgG antibody levels did not change significantly after treatment was stopped. Our data suggest that hyposensitization treatment can be stopped when specific IgE serum concentrations have fallen to low or unmeasurable levels and specific IgG antibody values are maintained, and that in a considerable number of patients venom immunotherapy has a lasting therapeutic and immunologic effect.

Adolescent↗
PubMed1985

Type I allergy to egg and milk proteins: comparison of skin prick tests with nasal, buccal and gastric provocation tests.

Provocation tests with egg or milk antigens were performed on symptomatic patients or those who were skin prick test positive to these antigens. Skin test positive patients responded immediately in 12/13 to nasal, in 7/15 to buccal and in 5/15 to gastric provocation tests. An immediate gastric response was within 1 h. The threshold dose for a positive result showed that tissue sensitivity from greatest to least was in the order: skin, nasal, buccal and gastric. None of the skin test negative group responded to any of the provocation tests. The results, particularly the nasal provocation, validate the skin prick test as a sensitive measure of type I allergy to defined foods. The relative insensitivity of buccal and gastric mucosae may explain positive skin test responses in asymptomatic subjects.

Dose-Response Relationship, Immunologic↗
PubMed1985

Improved sensitivity and specificity of sandwich, competitive and capture enzyme-linked immunosorbent assays for allergen-specific antibodies.

Indirect ELISA is widely used to detect specific antibodies but can suffer from high non-specific binding-particularly of IgG. The use of affinity-purified rabbit antibody-coated microtitre plates to bind antigen greatly increases sensitivity without a significant increase in non-specific binding of IgG. Capture, competitive and sandwich assay procedures gave comparable results for IgG antibodies; but only the sandwich assay was suitable for detection of IgE antibodies.

Allergens↗