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Biomedical subjects

X Baur

Publications and source records attributed to X Baur.

At least 127 records · Page 7Linked to original sources
PubMed1997

On the allergenicity of Hev b 1 among health care workers and patients with spina bifida allergic to natural rubber latex.

BACKGROUND: Recent studies have caused much controversy about the prevalence of IgE antibodies to Hev b 1 among health care workers (HCWs) and patients with spina bifida (SB) who are allergic to latex. This investigation was carried out to verify the results reported. METHOD: Serum samples from 140 patients with SB as well as from 105 HCWs allergic to latex were tested by enzyme allergosorbest test (EAST) and EAST-inhibition assay to evaluate the rate and degree of sensitization to highly purified Hev b 1. RESULTS: Eighty-one percent of patients with SB who were allergic to latex had IgE antibodies against Hev b 1. The prevalence of anti-Hev b 1 antibodies among HCWs allergic to latex was 52.3%. In 15 of 33 serum samples from patients with SB that were randomly tested, the IgE binding to commercial latex allergens could be completely inhibited by Hev b 1; in only six cases was the maximum inhibition of IgE binding to latex by Hev b 1 less than 50%. Testing two monoclonal anti-Hev b 1 antibodies with extracts of five brands of latex gloves revealed a predominant presence of Hev b 1 protein as a monomer or its aggregates. Molecular analysis of human leukocyte antigen-D region genes DRB and DQB1 suggested no statistically significant correlation between the human leukocyte antigen alleles tested and IgE responsiveness to Hev b 1. CONCLUSIONS: Our results indicate that Hev b 1 not only makes significant contributions to the IgE binding to latex, but it is also the unique sensitizer in about 45% of patients with SB who are allergic to latex.

Allergens↗
PubMed1997

Latex allergen elimination in natural latex sap and latex gloves by treatment with alkaline potassium hydroxide solution.

Antigenic proteins in latex products can cause type I allergy. We investigated the effects of potassium hydroxide (KOH) solution on the allergenicity of proteins in natural latex sap and latex gloves by using an EAST competitive inhibition immunoassay and skin prick test. Latex sap was mixed with KOH solution at different concentrations and incubated over various periods of time at room temperature. Latex gloves were washed in KOH solution for different times at 30 degrees C and 90 degrees C. Our immunoassay results for the subsequently extracted latex proteins demonstrated a KOH concentration-, temperature-, and time-dependent decrease in allergenicity, finally resulting in complete loss of IgE-binding activity. In the skin prick test, we found only four weakly positive reactions to proteins extracted from KOH-washed gloves in 30 latex-sensitized patients. In addition, up to 97% of the aqueous extractable protein content could be removed from latex gloves by washing in KOH solution under certain conditions. These results suggest that antigenic proteins in natural latex sap and latex gloves can be changed by treatment with KOH solution, which is followed by a loss of their capability to bind specific IgE antibodies from most latex-sensitized patients.

Allergens↗
PubMed1997

Protein and allergen content of various natural latex articles.

Proteins remaining in products made of natural rubber latex are potential sensitizers. In the present work, we quantified the releasable protein and allergen contents in 37 brands of latex gloves and 26 other latex products. Our results demonstrate the presence of widely varied protein and allergen contents in various latex articles and the lack of a correlation between the protein and allergen values. These findings may assist hospital management and medical staff to take effective preventive measures.

Allergens↗
PubMed1997

HLA class II antigens DR4 and DQ8 are associated with allergy to hevein, a major allergen of Hevea latex.

In this study we investigated the relationship between HLA class II alleles and the IgE-specific immune response to the 4.7 kDa polypeptide hevein of Hevea brasiliensis, a major latex allergen, 51 individuals with immediate-type latex allergy and 90 controls were examined for the polymorphisms in exon 2 of HLA-DRB1, 3, 4, 5 and DQB1 by sequence-specific oligonucleotide probe typing. 35 (69%) out of 51 latex-sensitized subjects showed positive hevein-specific IgE values. Analysis of the HLA data among these 35 subjects revealed increased phenotype frequencies for DR4 (22/35, 63%) and DQ8 (18/35, 51%) when compared with those in the 16 hevein-negative but latex-positive subjects (DR4: 2/16, 13%, p = 0.0009, Pc = 0.047; DQ8: 0/16, p = 0.0003, pc = 0.018) and with healthy controls (DR4: 22/90, 24%, p = 0.00012, pc = 0.013; DQ8: 16/89, 18%, p = 0.0003, pc = 0.036). Finally the DR4-DQ8 haplotype frequency was significantly elevated in hevein-positives when compared with hevein-negatives (51% vs. 0, p = 0.0003, pc = 0.034) or controls (51% vs. 18%, p = 0.0002, pc = 0.045) The present data suggest DR4 and DQ8 to be operating jointly as susceptibility factor for the allergy to hevein.

Adolescent↗
PubMed1997

Hexamethylene diisocyanate induction of transient airway hyperresponsiveness in guinea pigs.

The induction of lung injury and the development of airway hyperresponsiveness (AHR) by exposure to hexamethylene diisocyanate (HDI) were studied in a guinea pig model of occupational lung diseases. In addition to an unexposed control group of 16 guinea pigs (A), two groups (B, C) of 8 animals inhaled HDI atmospheres in the range of the threshold limit value (TLV) of 10 ppb for 6 h/day on 5 days/week over a period of 8 weeks. Airway responses to aerosols of 0.125, 0.25, 0.5, 1.0 and 2.0% acetylcholine (ACH) were measured in exposed as well as in unexposed animals. Basal values of respiratory mechanical and cardiovascular parameters were not significantly altered after 8 weeks of HDI inhalation (group B). Furthermore, additional acute challenge by 10 ppb HDI for a period of 60 min, performed under continuous registration of respiratory and cardiovascular parameters, did not cause any significant changes in functional parameters. After 8 weeks of HDI exposure, the amplitude of airway constriction as a response to 2.0% ACH, indicated by the changes in dynamic elastance (Edyn) rose significantly to almost 5 times the ACH response in group A(p < 0.0005). In group C of 8 guinea pigs, ACH response was evaluated after a latency period of 8 weeks. In this group, changes of airway responsiveness to ACH were significantly smaller than in group B without a latency period. They were comparable to those of group A. In summary, HDI-induced airway hyperresponsiveness to ACH in the guinea pig is reversible within 8 weeks of HDI avoidance. It is assumed that the augmented airway responsiveness indicates an increased risk of developing isocyanate-induced obstructive lung diseases.

Acetylcholine↗
PubMed1997

Flow-cytometric analysis of T-cell receptor expression in peripheral blood lymphocytes.

BACKGROUND: Lymphocytes of subjects sensitized to the insect-derived allergen Chi t 1-9 are, in response to the allergen, characterized by an elevated proliferation and increased expression of activation markers such as HLA-DR and CD25 in vitro. A restriction for HLA-DR B1 in monosensitized patients was found. OBJECTIVE: The aim of this study was to investigate whether the response to the allergen Chi t 1-9 involves the preferential cell surface expression of a specific alpha/beta T-cell receptor type. METHODS: The T-cell receptor repertoire was measured with 7 monoclonal antibodies to epitopes on the variable region of the alpha- and beta-chain by flow cytometry. Cell lines of 9 patients were established with Chi t 1-9, 6 with tetanus toxoid and 6 with phytohaemagglutinin in the presence of interleukin 2. In addition, non-stimulated lymphocytes as well as lymphocytes of 5 non-sensitized controls exposed to Chi t 1-9 were examined. RESULTS: Each of the 9 sensitized and 5 control subjects studied showed an individual pattern of lymphocyte expression for each T-cell receptor specificity. However, after stimulation specific to Chi t 1-9 for 2 weeks, a significant increase in V beta 8-expressing cells was measurable only in patients sensitized to Chi t 1-9. The cells of the 5 control subjects showed no significant changes due to the allergen stimulation. CONCLUSION: These data suggest that the expression of certain T-cell receptor types plays an important role in the development of Chi t 1-9 allergy.

Allergens↗
PubMed1997

Differentiation between cosensitization and cross-reactivity in wheat flour and grass pollen-sensitized subjects.

BACKGROUND: To diagnose baker's asthma, occupational sensitization to wheat flour should be distinguished clearly from influences of cosensitization such as it may exist in pollinosis patients. To define the route of sensitization, the cross-reactivity between wheat flour and grass pollen allergens was investigated. METHODS: Two groups of atopic individuals with or without professional contact to wheat flour were screened by skin prick test for their sensitization to wheat flour and grass pollen and, in the case of hints for cosensitization, by Enzyme Allergo Sorbent Test (EAST). Cross-reactivity between wheat flour and grass pollen allergens was investigated by IgE binding inhibition assay using sera of 20 cosensitized individuals and by immunoblots. RESULTS: The immunological cross-inhibition between wheat flour and grass pollen proves some proteins to share common allergenic determinants. Significant differences between bakers and individuals not occupationally exposed to flour could be seen in the inhibition of IgE binding to wheat flour. While the IgE binding to wheat flour allergens was only slightly inhibited by grass pollen proteins in baker's sera its inhibition was nearly complete by this extract in sera of nonexposed atopics. Immunoblots indicate that wheat proteins with a molecular weight of about 8-12 and 22 kD preferentially react with sensitized bakers' IgE and not with IgE of other individuals. IgE binding to grass pollen allergens in immunoblots and inhibition experiments showed no differences between bakers and other subjects. CONCLUSION: In the group of atopics without professional contact to flour, the positive test results from wheat flour obviously ensue from contact to cross-reacting grass pollen proteins whereas bakers are exposed and sensitized to allergens of both sources. Such cross-inhibition experiments help to identify the source of sensitization which may be difficult to obtain in case of cross-reacting allergens.

Asthma↗
PubMed1997

[Latex allergens: review of current knowledge].

Both health care workers and spina bifida patients are at risk to develop type I latex allergy since allergenic proteins of natural rubber latex are present in a variety of latex products. Natural latex contains more than 250 polypeptides and approximately 60 of them show IgE-binding characteristics. A multitude of these latex allergens has been identified, and their sensitization potency for both risk groups has been determined. While hevein (Hev b 6.02) is the major allergen in latex-allergic health care workers, 80% of latex sensitized-spina bifida children have IgE antibodies to the "rubber elongation factor" (Hev b 1). Almost all relevant latex allergens have been identified in natural latex products: however, no data on the allergen profiles of individual latex products exist. The knowledge of the major latex allergens enables improved diagnosis and to monitor the success of prevention strategies for decreasing the high prevalence of latex allergies.

Allergens↗
PubMed1997

[Ammonia as inhalatory irritant].

Bronchopulmonary damage caused by heavy exposure to ammonia may result in chronic obstructive bronchitis, bronchial hyperresponsiveness, in rare cases also in a combined ventilation pattern. Exposure to ammonia for several years, as it occurs in swine confinements in pig-fattening farms is associated with a shift-related decrease of FEV1, FEF25-75 and PEF. Several studies show that ammonia at the TLV (20 ppm) inconstantly causes severe cough. In this connection, patients frequently cannot perform maximum forced ventilation manoeuvres. This leads to reduced spirometric values which usually do not represent bronchial obstruction. This interpretation is supported by normal values obtained by body plethysmography. Nevertheless, corresponding disorders may be associated with significant health impairment. Altogether, the results point predominantly to long-term effects. Obviously, continuous inflammation of the airways favours the development of chronic bronchitis. On this basis, susceptible subjects respond with airway symptoms, especially cough, upon re-exposure.

Ammonia↗
PubMed1996

[The latency period between exposure and the symptoms in allergy to natural latex. Suggestions for prevention].

BASIC PROBLEM AND OBJECTIVE OF STUDY: Among persons working in the health care system allergies caused by natural rubber latex (NRL) are more common than among the general population, because the frequent use of latex gloves and other latex articles may cause sensitisation. A retrospective study was undertaken to determine the period before such an allergy occurs. PATIENTS AND METHODS: 63 patients (53 women and 10 men; mean age 31.3 +/- 8.3 years) with symptoms of type 1 (immediate response; IgE-mediated) allergy to NRL filled in a special questionnaire asking, among other items, about occupational history, duration and frequency of contact with latex gloves, as well as the course of occupational or other symptoms. All but five of the group had been in their job for less than 15 years. A prick test with 21 ubiquitous environmental allergens was performed on 62 of the patients. RESULTS: Two thirds of the patients had atopy. First symptoms of an allergy to latex developed at an average of 5 years (58.7 +/- 59.3 months) after starting work involving contact with latex products. In 59 persons the first symptoms were contact urticaria, in some together with rhinitis or dyspnea. The interval until onset of symptoms relating to the lower respiratory tract averaged a further 25.3 +/- 34.6 months. Symptoms developed earlier in patients with atopy than in those without (51.9 +/- 54.3 vs 76 +/- 69 months). CONCLUSIONS: The use of powdered natural rubber latex gloves should be discontinued to prevent the increasing incidence of sensitization to aerogenic latex and to protect those already sensitized from developing allergic bronchial asthma.

Adult↗
PubMed1996

Combined detection of CD44 isoforms by exon-specific RT-PCR and immunohistochemistry in primary human brain tumors and brain metastases.

Expression of CD44 has been implicated in tumor growth and metastasis. Here we demonstrate CD44 expression in primary human brain tumors (n = 44) and brain metastases (n = 7) by RT-PCR and immunohistochemistry. Standard CD44 was found to be expressed by the majority of primary brain tumors and brain metastases. For the first time to our knowledge, CD44 expression is demonstrated for acoustic neurinomas and pituitary adenomas. Exon-specific analysis by RT-PCR and indirect immunofluorescence revealed expression of alternatively spliced CD44 isoforms in the group of brain metastases only. However, in one glioblastoma multiforme, expression of CD44v5 and CD44v6 was found immunohistochemically. This tumor took an unusual clinical course giving rise to multiple intrahepatic and lymph node metastases. Quantitatively different expression of standard CD44 in gliomas versus meningiomas is reported (p < 0.01).

Alternative Splicing↗
PubMed1996

Humoral and cellular immune responses in asthmatic isocyanate workers: report of two cases.

Two workers (23 and 28 years old) developed rhinitis and bronchial asthma after occupational contact with the isocyanate MDI. Positive skin prick test results for MDI-HSA and IgE antibodies to all isocyanate-HSA conjugates were obtained in both cases, and the inhalation challenge test with MDI produced immediate and late asthmatic reactions. In the patch test and the stimulation assay of peripheral mononuclear blood cells, a specific sensitization to the diamine MDA (in both cases) and to further amines (in one case), as well as to hydrolysates of the respective diisocyanates, was seen, which appears to be independent of the IgE response to isocyanate-HSA conjugates. Our results offer evidence of IgE-mediated, as well as lymphocyte, responses induced by exposures to isocyanate products over several months or years.

Adult↗
PubMed1996

Role of substance P and neurokinin A in toluene diisocyanate-induced increased airway responsiveness in rabbits.

The aim of the present study was to examine the role of neuropeptides, especially substance P (SP) and neurokinin A (NKA), in toluene diisocyanate (TDI)-induced airway hyperresponsiveness (AHR) to acetylcholine aerosols. Thirty parts per billion of TDI in air administered over 4 hours caused a significant increase in the airway constrictive response to acetylcholine (ACH) aerosols in rabbits (DeltaRI: 245 +/- 30%, p < 0.005) without altering basic values of respiratory, cardiovascular or blood gas parameters. Inhalation of the aerosolized neuropeptides SP and NKA resulted in a similar increase in airway responsiveness (AR) to ACH as exposure to 30 ppb TDI. To determine whether neuropeptides contribute to TDI-induced AHR, we studied their effects after systemic treatment with capsaicin as well as after infusion of specific synthetic antagonists for SP and NK2 (NKA) receptors. CAPS treatment performed on 4 consecutive days as well as antagonists' infusion only moderately (p > 0.05) decreased airway responses to ACH. CAPS application prevented the TDI-induced increase in AR to ACH in all rabbits. The increase in airway resistance to ACH did not significantly change after TDI exposure (98 +/- 22% of the control response before TDI, p > 0.05). Simultaneous infusion of specific synthetic SP and NK2 receptor antagonists also abolished the TDI-induced increase in airway responses to ACH in all animals investigated (p > 0.05). The results of this study demonstrate that neuropeptides, especially the tachykinins SP and NKA, are important mediators in TDI-induced AHR in rabbits.

Acetylcholine↗
PubMed1996

Lymphocyte proliferation response to extracts from different latex materials and to the purified latex allergen Hev b 1 (rubber elongation factor).

BACKGROUND: Type I allergy to latex is a growing problem, especially among health care workers. A detailed study of the peripheral blood cell responses to latex allergens has not been reported. METHODS: Peripheral blood mononuclear cells of patients and healthy subjects were isolated and stimulated with protein extracts from latex sap and latex gloves and the purified latex allergen Hev b 1 (rubber elongation factor) at different concentrations to determine the antigen-specific proliferation response. The examined patients were sensitized to latex by occupational exposure (n = 23) and had rhinitis, conjunctivitis, contact urticaria, and/or asthma. Two control groups of nonsensitized subjects were studied: one occupationally exposed to latex (n = 8), and the second, not exposed to latex (n = 8). RESULTS: In general, only latex-exposed subjects responded to the different latex antigen preparations. Lymphocyte proliferation responses to latex sap extract were found in 65% of latex-sensitized subjects and in 37.5% of the latex-exposed healthy subjects. Latex glove extract induced a significant proliferative responses in 47.8% of latex-sensitized patients and in 25% of the latex-exposed individuals. Hev b 1 induced lymphocyte proliferation responses in 52% of the latex-sensitized patients and in 25% of the latex-exposed subjects indicating that Hev b 1 is relevant antigen in these latex-sensitized and latex-exposed groups. Peripheral blood mononuclear cells of 39.1% of the latex-sensitized subjects responded to all three allergen preparations (latex sap and latex glove extract, as well as Hev b 1). We could find no correlation between latex-specific IgE level and latex-induced lymphocyte proliferation response. CONCLUSION: Our data indicate that the 14 kd protein Hev b 1 is a relevant allergen in health care workers. It can be detected by specific IgE antibodies to Hev b 1, as well as in lymphocyte proliferation assay. In addition, our study suggests that antigen-specific proliferation response to latex is associated with exposure to latex, but not with the level of specific latex IgE. This may be useful for the evaluation and prediction of latex hypersensitivity development.

Adult↗
PubMed1996

Heating inactivates the enzymatic activity and partially inactivates the allergenic activity of Asp o 2.

BACKGROUND: Sensitization to various flours and flour additives in the baking industry has been known for some time. However, most studies refer to allergens in their native state. OBJECTIVE: The aim of our study was to find out how high temperatures during the baking process influence enzymatic and allergenic activities of the common flour additive alpha-amylase (Asp o 2), a relevant allergen for bakers derived from Aspergillus oryzae. METHODS: In order to assess the allergenicity of Asp o 2 during the baking process, four to 11 correspondingly sensitized bakers were investigated by Enzyme Allergo-Sorbent Test (EAST) with native Asp o 2 and Asp o 2 heated to 80, 90, 95, 99.8 or 200 degrees C. Furthermore, the enzymatic activity was assayed in simulated baking processes at the above mentioned temperatures. RESULTS: Elevated temperatures resulted in a gradual loss of IgE antibodies' recognition of Asp o 2 in two commercially available enzyme products. The enzymatic activity decreased more rapidly. Heating the enzyme to 200 degrees C abolished both the enzymatic and the allergenic activity of the enzyme. CONCLUSION: Based on these results, alpha-amylase in flour additives partially retains its allergenicity. This finding could be relevant for consumers.

Allergens↗