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Biomedical subjects

U Wahn

Publications and source records attributed to U Wahn.

At least 91 records · Page 5Linked to original sources
PubMed2000

Development of seasonal allergic rhinitis during the first 7 years of life.

BACKGROUND: Against the background of the controversial discussion about an increase in allergic rhinitis in recent years, intraindividual longitudinal data is lacking for IgE-mediated seasonal allergic rhinitis (SAR). Little is known about the development of SAR in terms of prevalence and incidence rates from birth to school age. OBJECTIVE: In a prospective birth cohort, we investigated the development of sensitization and symptoms of SAR. SAR should be defined with high specificity, and associated risk factors should be determined. METHODS: Annual longitudinal data about seasonal allergic symptoms and sensitization was available for 587 children from birth to their seventh birthday. The definition of SAR was based on a combination of exposure-related symptoms and sensitization. RESULTS: Up to 7 years of age, SAR developed in 15% of the children. Incidence and prevalence of symptoms and sensitization were low during early childhood (<2%) and increased steadily with age. Children in which SAR had already developed in the second year all were born in spring or early summer, resulting in at least two seasons of pollen exposure before manifestation of SAR. Risk factors assessed by multiple logistic regression analysis were male sex (odds ratio [OR] = 2.4), atopic mothers (OR = 2.6) and fathers (OR = 3.6) having allergic rhinitis themselves, first-born child (OR = 2.0), early sensitization to food (OR = 3.3), and atopic dermatitis (OR = 2.5), whereas early wheezing was not associated with SAR. CONCLUSION: The development of SAR is characterized by a marked increase in prevalence and incidence after the second year of life. Our longitudinal data further indicate that in combination with the risk of allergic predisposition, at least 2 seasons of pollen allergen exposure are needed before allergic rhinitis becomes clinically manifest.

Age Factors↗
PubMed2000

A new dipstick test (Allergodip) for in vitro diagnosis of latex allergy--validation in patients with spina bifida.

While there is established data on the value of various assays for determining specific immunoglobulin E (IgE) in serum, little has been reported about semi-quantitative dipstick methods. Therefore, in a pilot study we compared a new dipstick assay (Allergodip) with a well-evaluated commercial assay (Pharmacia CAP-system), in terms of sensitivity and specificity, in sensitized and nonsensitized, symptomatic and non-symptomatic patients with spina bifida. One-hundred and thirty-five patients with spina bifida (median age 10.8 years) were included in this study. Sixty-nine patients (51.1%) were positive in the CAP-system, 61 patients (45.2%) were positive in the Allergodip assay, and 67 patients (49.6%) were positive in a skin prick test with natural rubber latex milk. The concordance between the CAP-system and Allergodip was good. Forty-seven patients (34.8%) showed a positive response to the provocation test. The sensitivity of Allergodip was 85.1% compared with 91.5% for the CAP-system. Specificity was 75.0% for the Allergodip assay and 70.5% for the CAP-system. We conclude that the new dipstick test is a useful screening test for diagnosing sensitization to latex, e.g. when planning surgical interventions. However, in instances of doubtful reactions, discrepancies with clinical features or for scientific work it does not replace quantitative determination of specific IgE.

Adolescent↗
PubMed2000

Superantigen-induced T cell death by apoptosis: analysis on a single cell level and effect of IFN-gamma and IL-4 treatment.

BACKGROUND: A role of bacterial superantigens in several chronic inflammatory diseases has previously been proposed. Many of these diseases are associated with an imbalance of the T helper cell subsets and their cytokine production. METHODS: Peripheral blood mononuclear cells from healthy donors were incubated with various concentrations of staphylococcal enterotoxin B (SEB) with or without IL-4 or IFN-gamma. After different time points cell activation, proliferation, Fas expression, cytokine release and cell death via apoptosis were detected. RESULTS: SEB treatment resulted in sequential T cell activation, proliferation, Fas expression, cytokine release, subsequently followed by cell death via apoptosis in a dose- and time-dependent manner. This biphasic effect occurred preferentially in SEB-responsive cells represented by the expression of Vbeta3 and Vbeta12 on T cells. A strong relationship between T cell activation and apoptosis was observed. The amplitude between these events increased with the dose of SEB. The highest rate of apoptotic T cells was observed at a dose of 1,000 ng/ml SEB. Addition of IFN-gamma to SEB-treated cells significantly reduced the rate of apoptotic cells, whereas IL-4 prevented apoptosis only in SEB-untreated cells. CONCLUSION: These results support the concept that the dose of superantigen exposure determines the rate of T cell proliferation and subsequent cell death. This T cell immune response is modulated by the presence and the type of cytokines.

Adult↗
PubMed1999

Specific V beta T cell subsets are associated with cat and birch pollen allergy in humans.

Cognate interaction between TCRs and MHC class II molecules plays an important role in initiating the allergen-specific immune response. Therefore, we analyzed the TCR distribution of human PBLs of 56 atopic and nonatopic (NA) individuals, including 4 monozygotic twin pairs, from two extended and four nuclear families. The expression of 23 V beta and 3 V alpha elements was analyzed. The blood samples of symptomatic birch pollen-sensitized individuals that were taken < or = 6 wk after the birch pollen season (n = 8) showed a significantly higher frequency of V beta 16.1+ and V beta 20.1+ T cells compared with the blood samples of birch pollen-sensitized individuals that were obtained out of allergen season (n = 10) or from NA individuals (p < 0.0005 and p < 0.0001, respectively). Allergen-specific lymphocyte proliferation was detected in the allergic individuals, and the distribution of V beta 16.1+ and V beta 20.1+ T cells returned to normal levels after the pollen season. The frequency of these V beta-expressing T cells correlated with the levels of allergen-specific IgE Abs. In addition, cat-sensitized individuals (n = 8) showed a significantly higher frequency of V beta 17.1-expressing T cells than did NA individuals (p < 0.005). Our results indicate restricted TCR-V beta gene usage in cat and birch pollen allergies; we suggest that both genetic and environmental factors contribute to TCR-V beta gene expression and to the development of a specific T cell response.

Adolescent↗
PubMed1999

Serum IgE levels during the first 6 years of life.

OBJECTIVE: Total serum IgE percentiles were derived for a population-based sample of 4082 white children from Germany by weighted analysis of measurements from the Multicenter Allergy Study cohort. METHODS: The children of a prospective birth cohort were selected from a complete 1-year sample of newborns in 6 obstetric departments in 1990. Total IgE was determined at 1, 2, 3, 5, and 6 years of age in 1160 newborns of the cohort. By weighting these measurements for sex, atopic family history, and elevated cord blood IgE, total serum IgE percentiles were estimated for the original population-based sample of 4082 children. RESULTS: IgE levels increased by age (P <.0001). We found statistically significant higher total IgE values in boys than in girls at each age (P <.05). Within the group of atopic children, this sex difference was not statistically significant. CONCLUSION: Our estimates of total serum IgE levels for a large population-based sample were lower than most values previously reported. We suggest that for both clinical and epidemiologic and genetic studies, IgE values should be expressed with percentiles.

Aging↗
PubMed1999

Natural course of sensitization to food and inhalant allergens during the first 6 years of life.

BACKGROUND: Specific IgE antibody responses to alimentary and environmental allergens are one of the hallmarks of atopic diseases. The knowledge of the time course of allergic sensitization during early life may facilitate measures for preventive interventions. OBJECTIVE: In a prospective birth cohort study (the Multicenter Allergy Study [MAS]) we investigated annual incidence and prevalence rates of sensitization to food and inhalant allergens during the first 6 years of life. METHODS: For 216 children of a prospective birth cohort (MAS), a complete follow-up of specific IgE measurements to 9 food and inhalant allergens was available at 1, 2, 3, 5, and 6 years of age. On the basis of these measurements, sensitization rates were estimated for the reference population of 4082 children by weighted analysis. RESULTS: Annual incidence rates of sensitization to food allergens decreased from 10% at 1 year of age to 3% at the 6 years of age. Incidences of sensitization to inhalant allergen, however, increased with age (from 1.5% at 1 year to 8% at 6 years). Point prevalences of allergic sensitization to at least 1 of the 9 tested allergens increased from 11% at 1 year up to 30% at 6 years. This increase was due to markedly increasing sensitization rates to inhalant allergens (1.5% to at least 1 inhalant allergen at 1 year and 26% at 6 years of age), whereas sensitization rates to food allergens remained stable during the first 6 years of life (10%). CONCLUSION: The earliest serologic marker for atopic immunoreactivity in infancy is the presence of IgE antibodies to egg, followed by milk. The development of sensitization to inhalant allergens occurs mostly after infancy. Beyond the third birthday annual incidence and prevalence increase markedly with age. Rates for outdoor allergens are twice those for indoor allergens.

Air Pollutants↗
PubMed1999

Prevalence and role of serum IgE antibodies to the Staphylococcus aureus-derived superantigens SEA and SEB in children with atopic dermatitis.

BACKGROUND: The skin of patients with atopic dermatitis exhibits a striking susceptibility to colonization and infection with Staphylococcus aureus. In this context it has been previously shown that S aureus-derived superantigens could function as classic allergens, inducing production of functionally relevant specific IgE antibodies. OBJECTIVE: The aim of this study was to determine the prevalence and the role of circulating staphylococcal enterotoxin A (SEA)- and staphylococcal enterotoxin B (SEB)-specific IgE antibodies in children with atopic dermatitis. METHODS: In a cross-sectional study of 58 children with atopic dermatitis, the presence of IgE antibodies to SEA and SEB was correlated with the severity of the disease and the total and other unrelated allergen-specific IgE titers and density of colonization with S aureus strains on atopic skin and episodes of superficial S aureus skin infections. RESULTS: Twenty of 58 children (34%) were sensitized to superantigens (45% to SEB, 10% to SEA, 45% to SEA and SEB). In this group, severity of atopic dermatitis and levels of specific IgE to food and air allergens were significantly higher. The degree of disease severity correlated to a higher extent with the presence of SEA/SEB-specific antibodies than with total serum IgE levels. Density of colonization with superantigen-secreting S aureus strains was higher in the superantigen IgE-positive group. Sixty-three percent of these children experienced repeated episodes of superficialS aureus skin infections. CONCLUSIONS: Sensitization to S aureus-derived superantigens may be involved in disease exacerbation. The presence of SEA/SEB-specific antibodies had additional explanatory value for disease severity and therefore may be helpful in the characterization of children with severe atopic dermatitis.

Adolescent↗
PubMed1999

Effect of pre- and postnatal tobacco smoke exposure on specific sensitization to food and inhalant allergens during the first 3 years of life. Multicenter Allergy Study Group, Germany.

BACKGROUND: The study aimed to assess the effect of pre- and postnatal tobacco smoke exposure on specific sensitization to food allergens and inhalant allergens during the first 3 years of life. METHODS: A total of 342 children of a prospective and observational birth cohort study on atopy (MAS) were included on the basis of a complete follow-up of specific IgE measurements at the ages of 1, 2, and 3 years with available questionnaire information about the parental smoking habit at birth, 18 months, and 3 years of age. Study children were grouped into four exposure categories representing in utero and postnatal environmental tobacco smoke (ETS) exposure, and according to the number of cigarettes smoked by the parents. The effect on the development of allergic sensitization to food, outdoor, and indoor allergens by 3 years of age was determined by multiple logistic regression analyses. RESULTS: At the age of 3, children who were pre- and postnatally exposed to tobacco smoke had a significantly higher risk of sensitization to food allergens (odds ratio: 2.3, 95% C.I.: 1.1-4.6) than unexposed children. Children who were only postnatally exposed by a smoking mother also had a 2.2 times higher risk (95% C.I.: 0.9-5.9) of sensitization than unexposed children. These two categories (pre- and/or postnatal exposure) contribute to the significant overall effect of the tobacco smoke exposure (P< or =0.02). No significant association between tobacco smoke exposure and specific sensitization to inhalant allergens was observed. The determining risk factors for this type of sensitization were atopic family history and mite- and cat-allergen exposure levels. CONCLUSIONS: During the first 3 years of life, both prenatal and postnatal tobacco smoke exposure has an adjuvant effect on allergic sensitization which seems to be restricted to allergens to which children are mainly exposed, in combination with the peak of the ETS exposure around the first birthday.

Child, Preschool↗
PubMed1999

Evaluation of the risk of anaphylactic reactions by wasp venom-extract challenges in children.

Diagnostic sting challenges have been shown to provide information on the risk of further anaphylactic reactions to bee stings. We present a follow-up study in wasp venom-hypersensitive children after diagnostic venom extract challenges to analyze their risk of further anaphylactic reactions. Responses were obtained from 104 patients with wasp venom hypersensitivity out of 115 former patients. Only one of the 104 patients showed more than a severe local reaction to the sting challenge irrespective of the performance of a single or sequential challenge; therefore, only one patient received venom immunotherapy. The performance of a diagnostic sting challenge with wasp venom extract in children had a high negative predictive value of 94.6% for the risk of further systemic reactions. This was shown by analysis of later field stings, since 37 children experienced further field stings and only two of these children(5.4%) developed a mild systemic reaction (urticaria) equal to or less severe than the index sting. The value of the venom extract challenge can be interpreted in two ways: either it is less sensitive than a native sting challenge since the rate of systemic reactions to the challenge was very low, or the prognosis of wasp venom hypersensitivity in children is extremely favorable. Since the latter hypothesis is supported by the low incidence of systemic field sting reactions, we postulate that venom immunotherapy is necessary only in a minority of children with wasp venom hypersensitivity with an index sting reaction of Mueller grade I or II. However, the value of venom extract challenges as a general diagnostic instrument in children with Mueller I and II reactions due to wasp venom hypersensitivity may be questioned. It may have a place as a safe procedure in demonstrating to parents and physicians the often self-limiting natural course in most of these children.

Adolescent↗
PubMed1999

Outcome of double-blind, placebo-controlled food challenge tests in 107 children with atopic dermatitis.

BACKGROUND AND OBJECTIVE: Little is known about late phase clinical reactions during oral food challenges and the value of specific IgE in terms of sensitivity and specificity. METHODS: We therefore analysed retrospectively the clinical outcome of 387 oral provocations during double-blind, placebo-controlled food challenge tests in 107 children with atopic dermatitis. RESULTS: Eighty-seven (81%) children showed a positive clinical reaction to at least one challenge. The vast majority of children (94%) showed clinical symptoms to one or two allergens. One hundred and thirty-one of 259 (51%) of verum challenges and 1/128 (0.8%) placebo challenge were assessed as positive. Oral provocations with hen's egg showed the highest percentage of positive reactions (70%). Sensitivity of specific IgE to the four allergens tested was 90%, specificity 30%. Sensitivity of the parental history as a predictive factor was 48%, specificity 72%. Ninety-two of 131 (70%) children with positive verum provocations showed early reactions, 33 (25%) late and six (5%) combined early and late reactions. In 84/131 (64%) positive provocations one organ system was involved, while in 44 (34%) provocations two and in three (2%) challenges three organ systems were involved. Skin reactions were the most frequent clinical manifestation leading to positive reactions followed by gastro-intestinal and respiratory symptoms. There was no correlation between titration dose and specific IgE. The subgroup of non-sensitized children did not differ in terms of sex, age or titration dose from the total study population. CONCLUSION: Double-blind, placebo-controlled oral food challenges are helpful in distinguishing children with clinically manifested symptoms from those with food sensitization. Accurately identifying children with a clinical relevant food allergy may help to prescribe specific diets on a scientific basis, avoiding dietary limitations which may be unnecessary or even harmful.

Administration, Oral↗
PubMed1999

In vivo and in vitro studies on the residual allergenicity of partially hydrolysed infant formulae.

AIM: Because allergen-reduced formulae are widely used in the prevention and treatment of cow's milk allergy in children and because anaphylactic reactions have been reported for some hydrolysed formulae, it is of clinical relevance to know about the residual allergenicity of so-called hypoallergenic formulae. METHOD: We therefore studied the reactions of 20 children (mean age 1.6 years) with proven cow's milk allergy to a variety of formulae, using skin prick test, specific IgE in serum, protein content and RAST inhibition. RESULTS: Whereas all but two children with a clinically relevant cow's milk allergy had a positive skin prick test to cow's milk, some children still showed positive responses to the partially hydrolysed formulae. No child had a positive skin test to the amino acid formula. Specific IgE to the partially hydrolysed whey formula (median 0.28 U/ml) was significantly lower (p < 0.003) than to cow's milk. Specific IgE to the partially hydrolysed whey/casein formula, soy/pork collagen hydrolysate and the amino acid formula was in a low range (median values 0.19, 0.23 and 0.21 U/ml, respectively). While determination of the protein content of the formulae gave no valid information, RAST/EAST inhibition was highest for cow's milk, followed by the partially hydrolysed whey formula, partially hydrolysed whey/casein formula, soy/pork collagen formula, and the amino acid formula. CONCLUSION: Skin prick test and RAST inhibition test are suitable methods for determining the residual allergenicity of hydrolysed infant formulae, while determination of protein content using the applied modified Lowry method is not helpful.

Amino Acids↗
PubMed1999

Is atopic dermatitis predictable?

Atopic dermatitis (AD) is a common skin disease which affects 10 to 20% of the population, usually with onset during infancy. The frequency of AD appears to have increased over the past three decades. Attempts to identify parameters predictive of the development of AD have been made by many investigators during the last decades. Although genetic factors remain unmodifiable, avoidance of relevant trigger factors could modify the development of AD. This paper reviews and discusses findings of the last several years and outlines recent advances in genetic studies of AD. In spite of decades of intensive research and newly developed technology, the parental history of AD appears to be the most valuable predictive parameter. However, the predictive capacity is not sufficient to recommend it as screening instrument. At this time, a perinatal screening with the objective of primary prevention of AD does not seem feasible.

Cytokines↗
PubMed1999

Atopic eczema: how to tackle the most common atopic symptom.

The disease management of atopic eczema includes topical and systemic treatments as well as the control of allergic and non-allergic trigger factors. The basis for topical treatment is the regular use of emollients. In addition, anti-inflammatory treatment with -- preferably mild -- topical steroids is the treatment of choice. At least-one third of the children with atopic eczema during the first years suffer from clinically relevant food allergy requiring elimination diets for at least one or two years. The most common cause of superinfection is Staphylococcus aureus. Recent data suggests that it may induce purulent superinfection as well as enhance the inflammatory process by superantigen mediated T-cell activation. Also, a number of alternative treatment strategies have been investigated during the last decade: the use of gamma-linoleic acid has been shown to be of limited benefit, while studies on interferon-gamma and on high-dose intravenous gamma-globulin are still anecdotal. The long-term effectiveness of disease management in atopic eczema depends largely on the understanding of the disease process as well as on the compliance of the parents. Thus, coping with the problem will be easier if the patient or the parents have been educated in understanding the pathogenesis, the role of trigger factors, the possibilities of prevention and the different treatment strategies.

Adult↗