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Biomedical subjects

U Wahn

Publications and source records attributed to U Wahn.

At least 145 records · Page 8Linked to original sources
PubMed1996

Distribution and transmission of Pseudomonas aeruginosa and Burkholderia cepacia in a hospital ward.

Genotyping and antibiotic susceptibility testing were used to analyze Pseudomonas aeruginosa and Burkholderia cepacia strains from sink drain from 14 pediatric patients with cystic fibrosis (CF) and from hospital personnel as part of a 4 week prospective study of strain transmission in a pediatric ward. A total of 87.5% of all washbasin drains were contaminated with P. aeruginosa [10(2) to 10(5) colony forming units (CFU)/ml sink fluid], whereas B. cepacia was found only once in a sink drain. From the eight CF patients already infected with P. aeruginosa upon entering the ward, we isolated six genotypes that were identical with strains found in sink drains of the ward. Four of the 16 members of the personnel had one positive P. aeruginosa hand culture. B. cepacia was never found in patients or on personnel hands. Hand washing in contaminated sinks (> or = 10(3) CFU/ml) led to positive P. aeruginosa or B. cepacia hand cultures. P. aeruginosa or B. cepacia embedded in sputum were transmissable by hand shaking for up to 180 min, whereas both pathogens suspended in physiological saline were transmissable to other hands only up to 30 min. Genotyping of P. aeruginosa revealed strain transmission from CF patients or the environment to other patients or the personnel, as well as one transmission from the environment to a CF patient. The ability of CF sputum to prolong survival of P. aeruginosa and B. cepacia may be important for strain transmission. The results suggest that improved hygienic measures are required to prevent routes of bacterial transmission via the hands and sink drains.

Adolescent↗
PubMed1996

Effects of interferon-alpha on cytokine profile, T cell receptor repertoire and peptide reactivity of human allergen-specific T cells.

A large panel of T cell clones (TCC) specific for the recombinant form of Poa pratensis allergen (rKBG7.2 or Poa p9) were established from the peripheral blood of grass pollen-sensitive donor in the absence or presence of recombinant interferon-alpha (IFN-alpha) in bulk culture and their pattern of cytokine secretion, peptide reactivity and TCR V beta repertoire was examined. The majority of allergen-specific TCC derived in absence of IFN-alpha produced high amounts of interleukin-4 (IL-4) and IL-5 but not IFN-gamma (Th2 cells), while most of TCC derived in presence of IFN-alpha produced IFN-gamma but not, or limited amounts of, IL-4 and IL-5 (Th1 or Th0 cells). Of 24 TCC established in the presence of IFN-alpha, 22 were able to recognize a single allergen peptide, p26, while none of the clones established in the absence of IFN-alpha showed a similar specificity. The majority of both clones expressed the V beta 2 element regardless of whether they were established in the presence of INF-alpha, but the presence of IFN-alpha favored the expansion of V beta 2+, V beta 17+ and V beta 22+ Poa p9-specific T cells, whereas in the absence of IFN-alpha, other TCR V beta-bearing T cells (V beta 5, and V beta 6.7, and V beta 14) were expanded in addition to V beta 2+ T cells. None of V beta 2+ clones established in the absence of IFN-alpha reacted with p26, whereas all the V beta 2+ clones established in its presence in the absence of interferon-alpha reacted with p26, whereas all the V beta 2+ clones established in its presence reacted to this peptide. IFN-alpha also shifted the TCR V beta repertoire of both Poa p9- and Lolium perenne group 1 (Lol p1)-specific T cell lines generated from the same patient and from a different grass-sensitive individual. These data demonstrate that IFN-alpha modulates the development of allergen-specific T cells in vitro, and suggest that IFN-alpha may represent a useful tool for novel immunotherapeutic approaches in allergic disorders.

Allergens↗
PubMed1996

Prospective study of the atopy preventive effect of maternal avoidance of milk and eggs during pregnancy and lactation.

UNLABELLED: The preventive effect of maternal avoidance of cow's milk and eggs on the development of atopic dermatitis and sensitization to food allergens was studied in a prospective trial with families at high risk for atopy, intervention included encouraging exclusive breast feeding for at least 3 months and delaying the controlled introduction of solid foods. In addition, one group received a maternal diet with the complete avoidance of milk and eggs in the last trimester of pregnancy and during the period of exclusive breast feeding, another group had the same diet starting after delivery, and mothers of the third group had no dietary restrictions. The period prevalences of atopic dermatitis as well as the rates of specific sensitization to eggs and milk at 6 and 12 months were not significantly different between groups. We were unable to demonstrate a significant preventive effect of maternal diet. CONCLUSION: While breast feeding should be promoted for children at risk for atopy, mothers can be encouraged to stay on normal diet during pregnancy and the breast feeding period.

Animals↗
PubMed1996

The relevance of murine animal models to study the development of allergic bronchial asthma.

Bronchial asthma (BA) develops on the basis of a genetic predisposition and involves a characteristic sequence of changes in immune functions. In the immunopathogenesis, several phases can be distinguished: the initial stage is defined as the development of allergic sensitization. This step is dependent on: (i) T cell activation; (ii) IL-4 production; (ii) IgE synthesis; and (iv) mediator release by effector cells. The second phase of allergic inflammation as a consequence of the T cell dependent sensitization is characterized by IL-5 production and eosinophil activation and recruitment. Airway mucosa remodelling is the consequence of chronic inflammatory processes and represents the final stage of BA. In this article animal models will be discussed with regard to their relevance for these different phases in development of chronic allergic BA.

Animals↗
PubMed1996

The role of circulating food antigen-specific lymphocytes in food allergic children with atopic dermatitis.

In this study we evaluated antigen-specific in vitro responses of peripheral blood lymphocytes to lipopolysaccharide (LPS)-depleted food allergens in children who reacted to food challenge (cow's milk or hen's egg) with a deterioration of their atopic dermatitis (AD). Some of the children showed immediate symptoms (urticaria, bronchial asthma or gastrointestinal symptoms) as well. The proliferation of casein-stimulated lymphocytes from children reacting to cow's milk (age 0.7-5.9 years) was significantly higher (P < 0.01) than the proliferation of lymphocytes from 15 children with AD without milk allergy (age: 2.1-9.1 years). Twenty-eight T-cell clones (TCC) were established from the blood of three children sensitized to cow's milk and hen's egg who reacted to double-blind, placebo-controlled oral food challenge both with a deterioration of AD and with immediate symptoms. Surprisingly, 16 of 28 casein- or ovalbumin-specific TCC were CD8+. All TCC produced high amounts of IFN-gamma upon stimulation with concanavalin A. In addition, 75% of the CD4+ TCC and 44% of the CD8+ TCC secreted IL-4. Our results indicate that: (i) food-specific proliferation of blood lymphocytes can be detected in patients with clinically relevant food allergy with LPS-depleted allergens in vitro and (ii) circulating food-specific lymphocytes are CD4+ and CD8+ T cells with the capacity of producing both type 1 and type 2 cytokines.

Animals↗
PubMed1996

Allergen specificity of skin-infiltrating T cells is not restricted to a type-2 cytokine pattern in chronic skin lesions of atopic dermatitis.

The majority of allergen-specific T cells derived from inhalant allergen patch test lesions in patients with atopic dermatitis were previously found to produce a restricted type-2 cytokine pattern. Recent studies, however, have revealed that in chronic eczematous skin lesions of patients with atopic dermatitis, expression of the type-1 cytokine interferon-gamma predominates. To evaluate cytokine production by allergen-specific T cells in chronic atopic dermatitis, we established house dust mite (Dermatophagoides pteronyssinus)-specific T-cell clones from the dermis of chronic skin lesions of sensitized adult patients with atopic dermatitis. Frequencies of skin-derived T cells proliferating in the presence of Dermatophagoides pteronyssinus were between one in 138 and one in 4255, indicating that only a minority of skin-infiltrating T cells are allergen specific. When these cells were analyzed for their capacity to produce interferon-gamma, the majority (71%) of these cells were found to express interferon-gamma mRNA and to secrete interferon-gamma protein, either alone or in combination with interleukin-4. Phenotypic analysis revealed that 15% of skin-infiltrating allergen-specific T cells were CD8+. No selection of Vbeta elements was detected in Dermatophagoides pteronyssinus-specific T-cell clones. These studies demonstrate that allergen specificity of skin-infiltrating T cells is not restricted to a type-2 cytokine pattern in lesional atopic dermatitis. The notion that the majority of allergen-specific, skin-infiltrating T cells are capable of producing interferon-gamma further supports the concept that interferon-gamma expression has major pathogenetic relevance for the chronic phase of atopic dermatitis.

Adult↗
PubMed1996

Does benzyl benzoate prevent colonization of new mattresses by mites? A prospective study.

In 12 house-dust-mite-infested double beds, one of the mattresses was replaced by a new one, the other being regarded as a mite source. All new mattresses were treated in a double-blind fashion, with either benzyl benzoate or placebo before being placed on the bed as well as 1 year later. They were examined for mites and allergen concentrations over a period of 18 months. This period of time covered two mite seasons. Dust samples were taken bimonthly and analyzed by guanine test strip, microscopic mite counting, and determination of the mite allergens Der p 1 (Dermatophagoides pteronyssinus) and Der f 1 (D. farinae) by ELISA. Although, at the end of the observation period, the new mattresses still had significantly lower mite and allergen levels than the old mattresses, there were no significant differences between the placebo and the benzyl benzoate groups. In our setting, benzyl benzoate plus frequent cleansing was not significantly more effective in controlling mites than frequent cleansing alone.

Allergens↗
PubMed1996

Respiratory syncytial virus infection: its role in aeroallergen sensitization during the first two years of life.

Our aim was to study the influence of infection with the respiratory syncytial virus (RSV) in non-hospitalized infants on sensitization to aeroallergens and the early manifestation of atopy. Six hundred and nine infants from the prospective German Multicenter Cohort Study on Atopy were included, 38% of whom had an elevated atopic risk. RSV IgG and IgM antibodies were tested by ELISA with gradient purified RSV antigen. Specific IgE against mites, cat dandruff, birch and grass pollens and relevant nutritional antigens were tested with CAP-RAST-FEIA (Pharmacia, Sweden). Of the cord sera 99% were positive for RSV-IgG, 44.7% at one year and 64.2% (n = 265) at two years of age. The positivity rate after 12 months varied with the season of birth, the number of siblings and the degree of exposure to tobacco smoke; and correlated closely with attacks of wheezing during infancy. Twenty (2.8%) children were found to be sensitized against at least one aeroallergen at one year, and 28 (10.5%) at two years. By the first birthday, mite sensitization (n = 3) could only be seen in the RSV-infected children; grass pollen sensitization (n = 9) was associated with RSV seropositivity (logistic regression model including the confounders mentioned above: with RSV IgG < p = 0.048 > and IgM < p = 0.0006 >), as was birch sensitization (n = 5) with RSV IgM (p = 0.009). No such differences could be detected at two years. No correlation of RSV seropositivity to any allergic manifestation could be found. We conclude, that it is only in the first year of life, that RSV infection plays a significant role in promoting sensitization against aeroallergens, which do not at this time produce allergic symptoms.

Air Pollutants↗
PubMed1996

Sensitivity and allergy to latex in atopic and non-atopic children.

To study the sensitivity and allergy to latex in children, we investigated sera of 306 atopic and 303 non-atopic children (median age 4.5 years) for specific IgE to latex. In patients with specific IgE to latex, a questionnaire was sent to families and provocation tests were carried out. 60/306 atopic children (20.8%) and 1/303 non-atopic children (0.3%) showed specific IgE to latex in serum. The proportion of atopic, latex-sensitized and provocation positive children was 12/48 (25%). Specific IgE to latex was significantly higher (p < 0.03) in symptomatic compared to non-symptomatic patients. Specificity of a positive history was 92%, sensitivity 50%. Atopic dermatitis tended to be more prevalent among the 12 provocation positive atopic children (75%) compared to 36 provocation negative children (58%). There was a tendency that children of the symptomatic group underwent surgical interventions more frequently compared to non-symptomatic children. In conclusion, latex sensitization and latex allergy seem to have occurred more often in atopic children than previously known. Risk factors for the development of a sensitization to latex are atopy and the clinical diagnosis of atopic dermatitis; risk factors for a clinically manifest allergy to latex are an elevated specific IgE to latex, a positive history upon contact to material containing latex and probably frequent operations. Provocation tests should be performed to plan avoidance measures in latex-allergic children especially before surgical interventions.

Adolescent↗
PubMed1996

Comparison of three immunoassays for diagnosing sensitization to latex in children with spina bifida.

As natural rubber latex (latex) has become more widespread in our environment, physicians have become increasingly aware of the problem of possible allergic reactions. Many fatal and near-fatal incidents have been reported (mainly during surgery) (1-3) and data has been published on groups frequently exposed to latex, such as patients with spina bifida (4-9), healthcare professionals (10-12) and occupationally exposed persons (13). The incidence of latex allergy in children seems to be increasing (14). Tests are therefore needed which can reliably detect sensitization to latex. Our aim was to compare the diagnostic accuracy of three commercial immunoassays for measuring specific IgE in serum to latex.

Adolescent↗
PubMed1996

Specific IgE and IgG4 immune responses to tetanus and diphtheria toxoid in atopic and nonatopic children during the first two years of life.

BACKGROUND: In order to investigate, whether atopic and nonatopic children show differences in their specific IgE and IgG4 immune responses to tetanus (T) and diphtheria (D) antigens, we studied 538 children who had been followed from birth on and from whom records had been kept of all immunizations. METHODS: The prevalence of eczema and asthma was registered at regular intervals and the cumulative incidence of symptoms was determined at 24 months of age. Total serum IgE and specific IgE to a panel of nine allergens as well as T- and D-specific IgE and IgG4 were determined from the 24-months blood samples. RESULTS: Our results show that both atopic and nonatopic children are capable of mounting high levels of toxoid-specific IgE antibody responses. Children with cord blood IgE > 0.9 kU/1, serum IgE 10-100 kU/1 and > 100 kU/1 and at least one sensitization to an allergen at 24 months of age have significantly higher IgE responses to T and D (p < 0.001). In contrast, specific IgG4 antibody concentrations to T and D were not significantly different in children with elevated total IgE levels at 24 months. No differences in subgroups of children with or without early symptoms of atopy were observed. CONCLUSIONS: Our data indicate that IgE responses to toxoids such as T and D are not limited to infants with clinical manifestations of atopy in the first 2 years of life but are related to immunological parameters of atopy.

Asthma↗
PubMed1996

Relevance of serum ECP measurements for monitoring acute asthma in children.

To evaluate the role of serum eosinophil cationic protein (ECP) concentration as a monitoring parameter in acute bronchial asthma, 11 children (mean age 10.2 years) were studied during an acute exacerbation of their disease. Under an appropriate anti-inflammatory therapy, FEV1 increased significantly at day 1 (p < 0.05), day 14 (p < 0.05), day 28 (p < 0.03), and day 56 (p < 0.03) compared to baseline values at referral to hospital. Serum ECP concentration decreased in the group of patients significantly at day 28 (p < 0.02) and day 56 (p < 0.04). However, considering the individual serum ECP time courses, most of the patients did not show a uniform pattern of continuously decreasing values. From our data, we conclude that measuring serum ECP concentration during acute asthma episodes in children may play a role in some patients, whereas in others--probably those without acute eosinophil inflammation--monitoring by serum ECP concentration is of limited value.

Acute Disease↗
PubMed1996

Risk factors for latex allergy in patients with spina bifida.

OBJECTIVE AND METHODS: In order to study risk factors for latex allergy in patients with spina bifida, we investigated 165 patients with spina bifida (mean age 9 years). Besides answering a questionnaire, patients underwent skin-prick testing and determination of specific serum IgE to latex as well as a screening test for specific IgE to environmental allergens. A total of 80 patients (49%) were sensitized to latex according to the presence of specific IgE to latex. RESULTS: Skin-prick tests (SPT) with high ammonia latex milk were performed in 81 of our patients with spina bifida and were positive in 36 patients (46%). Concordance of SPT with specific IgE in serum was good. Nineteen out of 165 patients suffered from a clinically relevant latex allergy: five patients had a history of systemic reactions to latex (e.g. severe bronchospasm, anaphylactic reactions), mostly during surgery. Fourteen patients reported clinical symptoms while inflating a balloon; all these 19 patients were sensitized to latex. Number of operations ranged from one to 26 (mean 5 operations). Concentration of specific IgE to latex in serum correlated well with increasing numbers of operations. Some 32/76 patients (41%) with spina bifida who were sensitized to latex showed an atopic disposition, while 21 out of 81 latex-negative patients (26%) were atopic. Of 300 consecutive sera (mean age of patients 9 years) sent to our laboratory for routine determination of specific IgE, 144 (48%) were positive in terms of specific IgE to environmental allergens, of which 247144 (17%) were sensitized to latex. CONCLUSIONS: From our data we conclude that in order to minimize risk of severe systemic clinical reactions, all patients with spina bifida should be screened for their individual risk of latex allergy to plan preventive measures before operations. Main risk factors for latex allergy seem to be: more than five operations, atopic predisposition, history of clinical symptoms while inflating a balloon, and a sensitization with a CAP-class of > or = 4.

Adolescent↗
PubMed1996

[Cost-effectiveness studies of ambulatory educational programs for children with asthma and their families].

Increasingly, economic aspects become important in public health which makes necessary the quantification to economical and operational efficiency. One of the instruments applied in this process is cost-benefit-analysis, comparing preventive, curative and rehabilitative services under the aspect of cost and benefit and effectiveness. In this context, we have evaluated a project of ambulant training of asthmatic children and of their parents. We included 142 affected children and their parents, who were trained in the offices of 24 physicians. Evaluation was done with a questionnaire in which data were collected on asthma-management, on quality of life, and on cost-effectiveness. We looked at the year before starting the training and on the year after completion of the training. Treatment costs were decreased by training, life quality improved. Thus, ambulant training of asthmatic children and of their family is a useful and efficient part of preventive rehabilitation.

Adult↗
PubMed1996

[Outcome of structured asthma education in childhood and adolescence].

From 1988 onwards inpatient asthma training courses have been conducted in Berlin and Osnabrück. A controlled study on asthma training was carried out from 1990 to 1992 at both centres with the support of the Robert Bosch Foundation. In the first intervention group a subsequent training course of 6 months' duration was conducted with the inclusion and participation of the relevant family doctors in addition to the main training course. Scrutiny of the result was done before (T1), directly after (T2) and 12 months subsequent to the training course (T3). Improvements are seen in somatic data or cost-relevant data (emergency referral to the hospital or family physician, inpatient hospital periods, referral because of mild obstruction, days of non-attendance in school due to illness, severity of asthma, incidence of symptoms, stress endurance in sports). There is also a marked improvement in the self-assessment ability of the children and in the management of asthma, as well as a decrease in the asthma-specific feeling of anxiety. Self-reliance and independence, as well as early intervention, are improved as seen by the parents, whereas on the other hand unfavourable factors such as arguments on the proper asthma therapy are diminished. Especially with regard to confidence in controls on the state of health or disease there are significant changes that are more marked in the group subjected to subsequent training than in the group without such additional training, compared with the control group. Structured asthma training exercises a strongly positive effect on the daily management of asthma bronchiale by the families on different planes of coping with the disease. These effects are enhanced by subsequent aftercare by the family physician. Intensive care in the asthma outpatient wards alone does not sufficiently modify the factors contributing to good coping with the disease.

Absenteeism↗