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Biomedical subjects

X Baur

Publications and source records attributed to X Baur.

At least 109 records · Page 6Linked to original sources
PubMed1998

Water-soluble cooling lubricants induce airway hyperresponsiveness in rabbits.

Airway hyperresponsiveness (AHR) to water-soluble cooling lubricants (CL) induced by aerosol administered by tracheal tube was studied in a rabbit model of occupational lung disease. Two commercial CL were examined: the first was of the boric acid amine ester type without biozide (CL-BAE), the second was of the sulfonate type with biozide (CL-SB). 50, 5.0 or 0.5 mg/m3 CL was administered over a period of twice 2 h to six different groups of rabbits. Airway responsiveness (AR) to aerosols of 0.2% and 2.0% acetylcholine solution (ACH) was measured before and after each exposure to CL. A control group A of nine animals not exposed to CL showed no significant respiratory responses following inhalation of 0.2% ACH for 1 min. Conversely, inhalation of 2.0% ACH almost doubled the dynamic elastance (Edyn) in the ACH challenge test in this animal group. Airway resistance (RI), Edyn, slope of inspiratory pressure generation (delta Pes/tI), arterial pressure (Pa) and arterial blood gas tensions (PaO2, PaCO2) were not significantly altered during and after exposures to CL. However, after CL-BAE inhalation of 50 and 5 mg/m3 over 4 h, the amplitude of the ACH-induced airway obstruction indicated by the changes in Edyn rose significantly to almost five times the control response before exposure (group C, D, p < 0.005). Similar changes in RI and delta Pes/tI were obtained. After inhalation of 0.5 mg/m3 CL-BAE (group D), no significant changes in AR were observed. Similar to CL-BAE inhalation of 50 mg/m3, CL-SB caused enlarged AR in the ACH challenge test (group E), whereas no significant changes were found after exposure to 5.0 and 0.5 mg/m3 in groups F and G. In summary, CL aerosols with and without biozide in the range of 50 and 5 mg/m3 applied via tracheal tubes increased AR to ACH within 4 h of exposure in a time- and concentration-dependent manner. It has to be assumed that this augmented AR indicates an increased risk of developing lubricant-induced obstructive lung diseases.

Acetylcholine↗
PubMed1998

Acute exposure to hair bleach causes airway hyperresponsiveness in a rabbit model.

Ammonium persulphate (APS) and hydrogen peroxide (H2O2) are used as oxidants in many industrial processes and are the main constituents of standard hair bleaching products. In a previous study, it was demonstrated that aerosols of APS induce alterations in airway responsiveness. The present study examined whether exposure for 4 h to a hair bleach composition (containing APS, potassium persulphate and H2O2) or H2O2 could induce airway hyperresponsiveness and/or an obstructive ventilation pattern in a rabbit model. Exposure to the aerosols altered neither baseline airway resistance, dynamic elastance, slope of inspiratory pressure generation nor arterial blood pressure and blood gas measurements. Similarly to APS, hair bleach aerosols containing > or =10.9 mg x m(-3) persulphate (ammonium and potassium salt) in air and > or =1.36 mg x m(-3) H2O2 in air caused airway hyperresponsiveness to acetylcholine after 4 h of exposure. Aerosolized H2O2 (> or =37 mg x m(-3) in air) did not influence airway responsiveness to acetylcholine. The results demonstrate that hair bleaching products containing persulphates dissolved in H2O2 cause airway hyperresponsiveness to acetylcholine in rabbits.

Aerosols↗
PubMed1998

[Latex allergy: local hypersensitivity reaction cause by an esophageal catheter in compliance determination].

We report on two latex-allergic subjects who developed local hypersensitivity reactions after their lung compliance was measured by an oesophagus balloon catheter. Protein and allergen analyses of this catheter showed values of 85 and 9.8 micrograms per gram rubber. It is concluded that latex-allergic subjects should not undergo examinations with latex allergen-containing catheters. To our knowledge, this is the first report on allergic reactions caused by latex balloons of an oesophagus catheter.

Adult↗
PubMed1998

[Quantification of inhaled exposure to alpha-amylase in 2 bakeries].

BACKGROUND: Baker's asthma and baker's rhinitis are among the most frequent occupational diseases. A major cause is the high exposure to flour dust in the workplace and to allergenic enzymes like alpha-amylase from Aspergillus oryzae (allergen name: Asp o 2). METHODS: To quantify allergen exposure in the workplace, 31 personal dust samples in a conventional small bakery (six workers) and in a biobakery (seven workers) were collected. Using a recently developed two-site enzyme-linked immunosorbent assay based on monoclonal antibodies to alpha-amylase from Aspergillus oryzae, the allergen content of these dust samples was determined. RESULTS: Dust exposure in the biobakery was in the range between 3.5 and 12 mg/m3 (median: 5.2 mg/m3) and in the conventional bakery between 0.9 and 118 mg/m3 (median 8.5 mg/m3). 23 out of 31 exposure measurements showed values higher than 4 mg/m3 (threshold limit value for inhalable dust). In the biobakery, no fungal alpha-amylase could be detected. 15 out of 17 samples taken in the conventional bakery contained fungal alpha-amylase in the range between 0.2 and 88 ng per mg dust. The geometric mean of alpha-amylase exposure in this bakery was 13 ng Asp o 2/m3, and the maximum exposure was 4.8 micrograms/m3. In four cases, fungal alpha-amylase was detected although exposure to dust was below the threshold limit of 4 mg/m3. CONCLUSIONS: This study in two German bakeries shows that preventive measures to reduce contact to allergens have not been sufficiently realised. Relevant alpha-amylase exposure occurred at low dust levels illustrating that dust measurements are not adequate to control alpha-amylase exposure. For fungal alpha-amylase an additional threshold limit should be established.

Aspergillus oryzae↗
PubMed1998

[Asthma and rhinoconjunctivitis caused by castor bean dust].

A 57 years old trader of agricultural goods with chronic asthma had attended our medical department for diagnosis and therapy. Since more than 35 years the patient had always experienced work-related asthma episode and rhinoconjunctivities when he worked in workplace where castor-bean oil cake as fertilizer was sold. With the intensive contact with castor-bean containing goods beginning about eight years ago, his asthma attack had become chronic. The allergological diagnosis confirmed that he had high-degree type I-allergy to castor-bean allergens.

Agricultural Workers' Diseases↗
PubMed1997

Comparison of the binding potential of various diisocyanates on DNA in vitro.

Inhalation of diisocyanate vapors is associated with immediate-type hypersensitivity reactions and direct toxic responses. The genotoxic effects of diisocyanates have not been clarified. The aim of this study was to examine the changes in DNA following in vitro exposure to three most commonly used diisocyanates (toluene diisocyanate, TDI; methylenediphenyl-4,4'-diisocyanate, MDI; and hexamethylene diisocyanate, HDI) and to compare their binding potential using melting behavior of DNA and electrophoresis studies in DNA. Following incubation of DNA with MDI (pure and mix) and HDI we found no differences in the melting behavior compared to the control calf thymus DNA. However, DNA treated with TDI showed differences in the shape of the native DNA curves due to changes in hyperchromicity and exhibited 14% more DNA reconstitution after renaturation. The small changes in the melting behavior of native DNA do not suggest the formation of DNA intrastrand cross-links but rather conformational changes of single- and double-stranded DNA. These conformational changes were further explored by agarose electrophoresis of native and denatured calf thymus DNA. Control and all diisocyanate-exposed DNA showed no differences in the size of native DNA fragments. Conversely, electrophoresis of TDI mix-incubated DNA, following denaturation, showed a distinct reduction in the double-stranded DNA fragment size compared to the control, MDI-denatured (pure and mix), and HDI-denatured DNA. These findings may help to better understand the mechanisms of the genotoxic effect of TDI.

Animals↗
PubMed1997

Development of a two-site enzyme-linked immunosorbent assay for alpha-amylase from Aspergillus oryzae based on monoclonal antibodies.

A two-site monoclonal antibody ELISA was developed to quantify the allergen Asp o 2 (alpha-amylase from Aspergillus oryzae). Two mAbs recognizing distinct epitopes were selected, enriched by in vitro production in a modular minifermenter and affinity-purified. The first antibody was bound to microtiter plates which were then incubated with samples containing the allergen. Bound allergen was detected using a biotinylated second antibody and peroxidase-polymer-labelled streptavidin. The assay had a sensitivity of 0.6 ng/ml and did not react to high concentrations of wheat and rye flour or yeast proteins. The mAb ELISA will be useful in individual or epidemiological studies of baker's asthma to assess workplace allergen concentrations and the efficacy of allergen exposure prevention. It can be used as a standard assay for the quantification of alpha-amylase and the establishment and control of threshold limits in European bakeries.

Allergens↗
PubMed1997

[Exposure testing with powdered gloves in 60 health care workers with latex allergy].

BACKGROUND AND OBJECTIVE: Type 1 sensitization to natural rubber latex occurs in up to 22% of health care workers. Most sensitizations are due to the use of powdered latex gloves. Work place-associated exposure tests were performed to ascertain how frequently persons who developed breathing difficulties, rhinitis/conjunctivitis or obstructive respiratory tract illness when using powdered latex gloves are allergic to latex. PATIENTS AND METHODS: 60 persons (48 women and 12 men; mean age 29 +/- 7 years) with type 1 sensitization to natural rubber latex were studied. The past history was obtained through a questionnaire specially designed for those with latex allergy. Diagnostic measures included prick tests with different latex allergens, measuring the concentrations of total and latex-specific IgE and exposure trials, related to the work place, with powdered vinyl and latex gloves. RESULTS: The prick tests with various latex allergens produced significant skin reactions in 59 subjects, 58 had latex-specific IgE antibodies (0.47 kU/l- > 100 kU/l). Exposure tests with powdered latex gloves produced rhinitis in 55 and conjunctivitis in 38 persons, urticaria in 3 and cough in 19. Whole-body plethysmography demonstrated a significant rise in respiratory tract resistance in 13, a reduction in 1-second expiratory volume of at least 20% in 15. Abnormal values in both tests were noted in 8 subjects. CONCLUSION: The breathing difficulty reported by all subjects was in most cases due not to bronchial obstruction but to obstructed nasal breathing. In cases with breathing difficulty on exposure to latex gloves a latex allergy should be considered as the cause. Powdered latex gloves present a danger to health care personnel and should no longer be used.

Adult↗
PubMed1997

A longitudinal study of circulating lymphocyte subsets in the peripheral blood during the acute stage of Guillain-Barré syndrome.

Activated T cells are implicated in the pathogenesis of Guillain-Barré syndrome (GBS). Blood samples from 16 patients with GBS were studied with flow cytometry during the acute stage of their disease to define circulating lymphocyte populations. During the progressive phase of GBS the T-suppressor/inducer (CD4/CD45RA) subset was decreased (10.3 +/- 4.4%, P < 0.05) and the T-helper/ inducer (CD4/CD29) subset was increased (34.9 +/- 9.2%, P < 0.05) compared to sex and age matched patients with other neurological diseases (OND, 15.5 +/- 5.7% and 27.8 +/- 8.6%, respectively) and healthy controls (16.5 +/- 6% and 28.1 +/- 8.5%, resp.). Within the CD8 population, the activated T-cytotoxic/suppressor (CD8/CD38) subset was increased during the progressive (13 +/- 10.1%, P < 0.05) and plateau phase (16.4 +/- 16.9%, P < 0.01) of GBS compared to OND patients (6.2 +/- 2.3%) and healthy controls (5.8 +/- 2.5%). The proportion of activated T cells (CD3/CD25) was increased during the progressive (9.3 +/- 3.8%, P < 0.05) and plateau phase (11.5 +/- 5.5%, P < 0.01) compared to OND patients (6.6 +/- 2.7%) and healthy controls (5.5 +/- 2.5%). The changes of T cell subsets normalized during the early recovery phase of GBS. 2 patients with serological evidence of antecedent cytomegalovirus (CMV) infection had abnormal high proportions (mean +/- 2 (SD) of healthy controls) of CD8 lymphocytes and correspondingly abnormal low proportions of CD4 lymphocytes during all phases of GBS. In contrast, the CD8 proportions were abnormal low in 3 patients with serological evidence of recent Campylobacter jejuni infection. There was no correlation between the proportions of lymphocyte subsets and the disability score during the maximum of the disease and after half a year. In conclusion, we found further evidence of T cell activation during the acute stage of GBS by the demonstration of an increased proportion of activated CD8+ T cells, which may be directly cytotoxic to Schwann cells. The abnormalities of the CD8 subset in some GBS patients seem to depend on the nature of the preceding infection.

Acute Disease↗
PubMed1997

Changes in high molecular weight DNA fragmentation following human blood exposure to styrene-7,8-oxide.

Styrene-7,8-oxide (S7,8O) is the major in vivo metabolite of styrene and is a genotoxic agent potentially carcinogenic to humans. It is known to cause DNA strand breaks and adducts. We studied high molecular weight DNA fragmentation in white blood cells following incubation of blood with S7,8O from individuals with no previous exposure to this compound. To better understand the effects of S7,8O, we also examined blood exposed to hydrogen peroxide (H2O2) a typical oxidant that is linked to oxidative stress. All individuals in this study showed a variable reduction in high molecular weight DNA fragments determined by laser densitometry compared to untreated controls for both S7,8O and H2O2 treated samples. This decrease was independent of the concentration and length of exposure of blood to S7,8O and H2O2. An increase in low molecular weight DNA fragments from samples treated with S7,8O and H2O2, compared to untreated samples was also noted. Similarities in the reduction of HMW-DNA fragments after S7,8O and H2O2 exposure suggested a similar mechanism of HMW-DNA damage. It was surmised that S7,8O exposure in blood may induce high molecular weight DNA fragmentation due to oxidative stress.

Carcinogens↗
PubMed1997

No evidence for the influence of HLA class II in alleles in isocyanate-induced asthma.

Isocyanates are one of the main causes of occupational asthma. The aim of this investigation was to study the possible genetic background of isocyanate-induced asthma under consideration of the atopy status and different lung function parameters. We investigated the human leukocyte antigen (HLA) genes DRB1,3,4,5, DQB1, and DQA1 in 55 isocyanate-exposed patients with workplace-related dyspnea (32 asthmatics, 23 nonasthmatics) and 90 nonexposed controls. In contrast to other studies, we found no significant differences for any HLA class II allele tested in our study group. Furthermore, no significant differences concerning the aspartic amino acid residue 57 of DQB1 was observed. Therefore, we are unable to confirm an involvement of a specific HLA class II allele or DQB1-Asp57 in conferring susceptibility to isocyanate asthma in our study group.

Adult↗
PubMed1997

Latex allergen database.

Two-dimensional (2-D) electrophoresis followed by immunoblotting and N-terminal protein microsequencing were used to characterize and identify the IgE-reactive proteins of Hevea latex that are the main cause of the latex type I allergy affecting especially health care workers and spina bifida children. This approach generated a comprehensive latex allergen database, which facilitated the integration of most of the latex allergen data presented in the literature. The major latex allergens Hev b 1, Hev b 3, Hev b 6 and Hev b 7 have been localized on our 2-D maps. Moreover, we were able to identify six previously undescribed IgE-binding latex proteins, namely enolase, superoxide dismutase, proteasome subunit C5, malate dehydrogenase, triosephosphate isomerase and endochitinase. The generated latex 2-D maps will provide valuable information to develop strategies for the isolation of the novel IgE binding proteins in order to study the frequency of sensitization among both risk groups. Detailed knowledge of all proteins involved in latex allergy will allow better diagnosis of latex allergy and to monitor the success of prevention strategies that are needed to reduce the high prevalence of latex allergy among both risk groups.

Allergens↗
PubMed1997

Modulation of airway responsiveness to acetylcholine by nitric oxide in a rabbit model.

Nitric oxide (NO) is an important mediator in the regulation of bronchial muscle tone and airway responsiveness. We investigated the influence of exogenous NO on airway responsiveness to acetylcholine aerosols (ACH) in normal and in hyperresponsive rabbits. White New Zealand rabbits were anesthetized, intubated, and breathed room air spontaneously. Responses of respiratory parameters in ACH challenge tests were measured. In group A the influence of NO on ACH infusion-induced airway constriction was measured. Airway responses to aerosols from 0.25 to 8.0% ACH solutions in saline were measured with 150 and 300 ppm NO inhalation (groups B and C) and compared with the same animals' responses without NO. Moreover, we examined the influence of NO synthase inhibition on airway responsiveness (group D) and the modulatory effect of NO in hyperresponsive animals (group E). 300 ppm NO inhalation significantly decreased the bronchoconstrictor response to intravenously administered ACH (group A). However, the baseline value of dynamic elastance (Edyn) was only marginally lower under the influence of 300 ppm NO. During inhalation of 150 or 300 ppm NO, responses to nebulized 2.0% and less ACH solutions remained nearly unaltered. Responses to aerosols of 4.0 and 8.0% diminished significantly (groups B and C). Following 40 min of aerosolized N-nitro-L-arginine-methyl ester (L-NAME) solution (a NO synthase inhibitor, 1.2 mM) inhalation, the response of Edyn to ACH increased significantly in group D. In group E, animals inhaled 500 mg/m3 ammonium persulfate (APS), an oxidant with various industrial applications, after the first ACH challenge test (0.2, 1.0, and 2.0% ACH). After 2 h of APS exposure, the ACH-induced broncho constriction was increased significantly in the challenge test. After another 2 h of APS inhalation, the airway responsiveness to ACH was tested under the influence of 300 ppm NO. NO significantly decreased the response to ACH to almost the same level as before APS exposure. The results indicate that responses to high ACH concentrations as well as an APS-induced increase in ACH responsiveness were effectively reduced by high concentrations of inhaled NO.

Acetylcholine↗
PubMed1997

Detection of 8-hydroxydeoxyguanosine, a marker of oxidative DNA damage, in white blood cells of workers occupationally exposed to styrene.

Styrene-7,8-oxide (SO), the major in vivo metabolite of styrene, is a genotoxic compound and a potential carcinogenic hazard to occupationally exposed workers. The aim of the present work was to investigate the ability of styrene exposure to induce formation of 8-hydroxy-2'-deoxyguanosine (8-OHdG) in white blood cells (WBC) of boatbuilders occupationally exposed to styrene. The study of these adducts was conducted to see if styrene exposure can cause oxidative damage of DNA. The 8-OHdG/10(5) dG ratio from 17 styrene-exposed workers showed significant increases (mean +/- SD, 2.23 +/- 0.54, median 2.35, P < 0.001) in comparison to the controls (1.52 +/- 0.45, median 1.50). However, 11 out of 17 workers who were between the ages of 32 and 60 years and had been occupationally exposed to styrene for > 10 years showed higher 8-OHdG/10(5) dG ratios (2.31 +/- 0.62, median 2.37) in comparison to 6 workers with < 6 years of occupational styrene-exposure (2.11 +/- 0.36, median 2.05; P > 0.05, no significant difference between the two groups of workers). The studies presented here provide an indication that styrene exposure can result in oxidative DNA damage.

8-Hydroxy-2'-Deoxyguanosine↗
PubMed1997

Characterization and identification of latex allergens by two-dimensional electrophoresis and protein microsequencing.

BACKGROUND: Proteins of natural rubber latex cause IgE-mediated sensitization in 3% to 18% of health care workers and in up to 50% of patients with spina bifida. OBJECTIVE: This study was aimed at the generation of a comprehensive latex protein database by two-dimensional electrophoresis (2-DE). METHODS: Proteins extracted from fresh Hevea brasiliensis latex were separated by 2-DE. IgE-reactive proteins were analyzed by immunoblotting with sera of health care workers with latex allergy. Protein microsequencing and monoclonal antibodies were used to identify the latex allergens. RESULTS: The latex C-serum 2-DE map was very complex and exhibited about 200 distinct polypeptides. The proteins eluted from the latex particles consisted primarily of two groups of acidic proteins located in the 8 to 14 kd and 22 to 24 kd areas of the 2-DE map. Major IgE-reactivity was detected with C-serum proteins in the 56, 45, 30, 20, 14, and <6.5 kd areas of the immunoblots. The 8 to 14 kd particle proteins exhibited distinct IgE reactivity, whereas the 22 to 24 kd proteins were not stained. Seven of the soluble IgE-reactive protein spots showed high homology with enolase, superoxide dismutase, triosephosphate isomerase, proteasome subunit, and chitinase and represent previously undescribed latex allergens; whereas nine protein spots corresponded to known latex allergens, namely prohevein, hevein, prohevein C-domain, and hevamine. As identified by monoclonal antibodies, the IgE-reactive latex particle proteins mainly represent the allergenic rubber elongation factor. CONCLUSIONS: Two-dimensional electrophoresis, followed by immunoblotting and protein microsequencing, can rapidly identify a large number of IgE-binding latex proteins. The 2-DE latex maps generated will provide valuable information for the development of strategies to isolate the relevant latex allergens. Because the novel latex allergens are common plant enzymes, they may also act as cross-reacting proteins in various foods.

Adult↗
PubMed1997

Isolation and identification of hevein as a major IgE-binding polypeptide in Hevea latex.

BACKGROUND: Polypeptides in Hevea latex are known as the major cause of latex type I sensitivities. So far, only a few of them have been characterized. METHODS: Proteins with a molecular weight lower than 10 kd in fresh Hevea latex were separated by ultrafiltration and further characterized by liquid chromatography on-line-coupled electrospray mass spectrometry. Hevein in this fraction was then purified by preparative reverse-phase high-performance liquid chromatography and characterized by matrix-assisted laser desorption ionization mass spectrometry and protein sequencing. Skin prick tests, enzyme-linked allergosorbent tests, and inhibition immunoblotting were performed to show the allergenicity of the purified hevein. RESULTS: Hevein, a 4.7 kd polypeptide, is the predominant component in the fraction with latex proteins of smaller than 10 kd. Specific IgE antibodies to hevein were detected by enzyme-linked allergosorbent test in 48 of 64 (75%) sera from health care workers allergic to latex and in three of 11 (27%) sera from patients with spina bifida and hypersensitivity reactions to latex. Inhibition immunoblotting demonstrated that the preincubation of 14 sera and a serum pool from patients allergic to latex with purified hevein completely inhibited IgE binding to the 20 kd protein, which has been recently reported to be a major allergen in latex (prohevein). Skin prick testing showed a positive reaction to hevein in 17 of 21 (81%) patients with latex allergy. CONCLUSIONS: The results clearly demonstrate that hevein is an important latex allergen, and the IgE-binding capacity of prohevein in latex is mostly attributed to hevein, the N-terminal domain of prohevein.

Adolescent↗