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Biomedical subjects

U R Müller

Publications and source records attributed to U R Müller.

At least 19 recordsLinked to original sources
PubMed2003

Discriminating two classes of toxicants through expression analysis of HepG2 cells with DNA arrays.

Microarray technology provides a rapid and cost-effective method to associate specific cellular responses with unique gene expression patterns. If characteristic expression patterns of a small number of genes could be associated with drug toxicity, this association may be used for toxicity prediction, and thereby to reduce the need for traditional toxicity testing. To test this hypothesis, we have designed an array composed of 92 known human genes of toxicological interest (including seven housekeeping genes) and eight bacterial controls. HepG2 cells were treated with either ethanol or one of two quinone containing anticancer drugs, mitomycin C or doxorubicin. RNA was isolated from treated and untreated cells, differentially labeled with fluorescent dyes, and then hybridized to the array. Our results show that the expression patterns induced by ethanol and the anticancer drugs are different. Both of the anticancer drugs, but not ethanol had a differential effect on the regulation of several genes, including CYP4F2/3, CYP3A3, TNFRSF6 and CHES1, demonstrating that the two drugs might function through a similar mechanism, which differs from that of ethanol. These results suggest that microarray-based expression analysis may offer a rapid and efficient means for assessing drug toxicity.

Antineoplastic Agents↗
PubMed2001

Novel surface and multicolor charge coupled device-based fluorescent imaging system for DNA microarrays.

We report a novel support, concomitant attachment chemistry, and a fluorescent imaging system for DNA microarrays. The support consists of soda lime glass coated with a layer of chromium, which eliminates any autofluorescence from the underlying glass substrate and reduces nonspecific probe binding. Attachment of DNA fragments exceeding 300 nucleotides in length is achieved without chemical modifications of either the chrome surface or the DNA itself. The charge coupled device (CCD)-based imaging system employs a 175 W xenon arc lamp as the light source, allowing the use of many different fluorophors. A 14 mm x 9 mm sample area is imaged with a single exposure, which takes between 5 and 20 s for each color plane in typical genomic comparative genomic hybridization type assays. The spatial resolution is limited only by the pixel size of the CCD chip (9 microm). The oblique illumination geometry combined with effective background reduction afforded by the chromium surface enables the system to achieve a detection limit of <5 x 10(7) fluorophors/cm(2) with 10 s integration. In a model system with arrayed lambda DNA targets a dose response was observed over four orders of magnitude in response to hybridizations with increasing amounts of the fluorescent labeled lambda probe.

Escherichia coli↗
PubMed2001

New developments in the diagnosis and treatment of hymenoptera venom allergy.

According to most textbooks, diagnostic tests with Hymenoptera venoms are reliable, and immunotherapy with these venoms in Hymenoptera-venom-allergic patients leads in near to 100% to full protection. Careful analysis of the literature shows however that the specificity of diagnostic tests is far from perfect and that both efficacy and tolerance, especially in patients receiving honeybee venom immunotherapy, are still suboptimal. The major allergens of honeybee and vespid venoms are now available in recombinant form. Preliminary trials analyzing diagnostic tests with recombinant allergens in honeybee venom allergy are promising: the specificity is clearly increased in both skin testing and in determining venom-specific IgE antibodies when compared to natural venom allergens. An important recent finding is the frequent association of severe Hymenoptera venom allergy and elevated basal serum levels of the mast-cell-specific enzyme tryptase. Elevated levels are found in up to 30% of the patients with a history of severe shock reactions following Hymenoptera stings. The current findings indicate that basal tryptase levels indicating an increased mast cell load are much more frequent than previously thought and are a risk factor for severe or even fatal sting reactions. Premedication with antihistamines in the initial phase of venom immunotherapy reduced both local and systemic allergic side effects in several controlled studies. In a retrospective analysis of one of these trials it was found that reexposure during immunotherapy resulted in significantly more systemic allergic reactions in patients on placebo than on antihistamine premedication, suggesting that initial antihistamine premedication might increase the efficacy of venom immunotherapy. Different ways of allergen modification for venom immunotherapy have been proposed. While the results with chemical modifications were not convincing, recent studies with T-cell epitope peptides from the major bee venom allergen phospholipase A(2) look promising. Patient-tailored cocktails of recombinant venom allergens or isoforms thereof may be another possibility in the future. A number of prospective studies analyzing the duration of venom immunotherapy required for long-term protection have been published in the last decade. While most patients are still fully protected 1 year after discontinuation of therapy, relapses may occur in up to 20% of patients reexposed many years after treatment. Various risk factors for such relapses have been identified.

Allergens↗
PubMed2000

Are anaphylactic reactions to snake bites immunoglobulin E-mediated?

BACKGROUND: Bites by poisonous European snakes of the genus Vipera lead to local tissue damage and systemic symptoms such as generalized oedema, hypotension, gastrointestinal symptoms, haemolysis and renal dysfunction. Not rarely anaphylactic symptoms like urticaria, localized angioedema and asthma are observed. OBJECTIVE: To look for snake venom-specific immunoglobulin (Ig) E antibodies in patients with a history of bites by European vipers and for cross-reactions with Hymenoptera venoms, that have a similar composition. METHOD: Ten patients with a history of bites by Vipera aspis or Vipera berus were investigated. Three patients had been bitten only once, and two of these had developed only local reactions. Four reported previous allergic reactions to Hymenoptera stings. All patients, 10 Hymenoptera venom-allergic and five nonallergic individuals who served as controls underwent i.c. skin test endpoint titration with snake (V. aspis, V. berus) and Hymenoptera venoms (honey bee, Vespula spp.) and were investigated for specific serum IgE antibodies to the same venoms. RESULTS: Seven of the eight patients with systemic snake bite reactions had both positive skin tests and serum IgE antibodies to snake venoms, while these tests were negative in the two patients with only local reactions to snake bites and all controls. Seven of the eight patients with systemic snake bite reaction also had positive skin tests and specific IgE with one or both Hymenoptera venoms. By RAST-inhibition with sera of four patients with high IgE to both Vipera and Hymenoptera venoms, partial cross-reactivity could be demonstrated in one. CONCLUSIONS: Anaphylactic reactions following snake bites may be IgE-mediated, especially in patients with repeated bites.

Adult↗
PubMed1999

Adaptation of capillary isoelectric focusing to microchannels on a glass chip.

As a first step toward adaptation of capillary isoelectric focusing (cIEF) to microchannels on a glass chip, we have compared the three most common mobilization methods: chemical, hydrodynamic, and electroosmotic flow (EOF)-driven mobilization. Using a commercial cIEF apparatus with coated or uncoated fused-silica capillaries, both chemical and hydrodynamic mobilization gave superior separation efficiency and reproducibility. However, EOF-driven mobilization, which occurs simultaneously with focusing, proved most suitable for miniaturization because of high speed, EOF compatibility and low instrumentation requirements. When this method was tested in a 200-micron-wide, 10-micron-deep, and 7-cm-long channel etched into planar glass, a mixture of Cy5-labeled peptides could be focused in less than 30 s, with plate heights of 0.4 micron (410 plates/s) upon optimization. For a total analysis time of less than 5 min, we estimate a maximum peak capacity of approximately 30-40. Interestingly, the order of migration was found to be reversed compared to capillary-based focusing.

Glass↗
PubMed1998

Long-term protection after stopping venom immunotherapy: results of re-stings in 200 patients.

BACKGROUND: Venom immunotherapy (VIT) protects most patients allergic to Hymenoptera stings while booster injections are continued. Few data on long-term protection after discontinuation of treatment are available. OBJECTIVE: We sought to investigate protection from re-stings over a prolonged period after stopping VIT. METHODS: Re-sting data were obtained from 200 of 322 patients in whom VIT had been stopped between 1988 and 1992 after a duration of at least 3 years. The 25 (12.5%) patients who again developed systemic allergic reactions were compared with 50 matched patients without re-sting reactions. Clinical data and diagnostic parameters (i.e., skin sensitivity and specific IgE and IgG) were studied. RESULTS: Of the 25 patients who had re-sting reactions, 19 had been treated with bee venom (relapse rate, 15.8%), and six had been treated with Vespula venom (relapse rate, 7.5%). About half of the re-sting reactions occurred on the first resting after stopping VIT. Most of these reactions were mild, whereas the majority of reactions occurring after repeated re-stings were severe. When re-sting reactions were related to the total re-stings per year, an accumulation of sting reactions was observed in years 3 to 5 after stopping VIT. Patients with re-sting reactions had been receiving VIT for a significantly shorter duration (43.35 months) than those with continued protection (54.65 months) (p < 0.01). Of the diagnostic parameters, only a negative intracutaneous skin test at 10(-3) gm/L predicted long-term protection reliably. CONCLUSION: Venom immunotherapy of 3 to 5 years duration induces long-term protection in most patients. In rare occasions severe re-sting reactions may, however, occur, especially after repeated re-stings.

Adolescent↗
PubMed1998

Bee sting allergy in beekeepers.

BACKGROUND: Beekeepers are strongly exposed to honey bee stings and therefore at an increased risk to develop IgE-mediated allergy to bee venom. OBJECTIVE: We wondered whether bee venom-allergic beekeepers were different from normally exposed bee venom-allergic patients with regard to clinical and immunological parameters as well as their response to venom immunotherapy. METHOD: Among the 459 bee venom-allergic patients seen over the 5 year period 1987-91, 62 (14%) were beekeepers and 44 (10%) family members of beekeepers. These two groups were compared with 101 normally exposed bee venom-allergic patients matched with the allergic beekeepers for age and sex, regarding clinical parameters, skin sensitivity, specific IgE and IgG antibodies to bee venom as well as safety and efficacy of venom immunotherapy. RESULTS: As expected, allergic beekeepers had been stung most frequently before the first allergic reaction. The three groups showed a similar severity of allergic symptoms following bee stings and had an equal incidence of atopic diseases. Allergic beekeepers showed higher levels of bee venom-specific serum IgG, lower skin sensitivity and lower levels of bee venom specific serum IgE than bee venom-allergic control patients. A negative correlation between number of stings and skin sensitivity as well as specific IgE was found in allergic beekeepers and their family members, while the number of stings was positively correlated with specific IgG in these two groups. Venom immunotherapy was equally effective in the three groups, but better tolerated by allergic beekeepers than the two other groups. The majority of allergic beekeepers continued bee-keeping successfully under the protection of venom immunotherapy. CONCLUSION: The lower level of sensitivity in diagnostic tests and the better tolerance of immunotherapy in allergic beekeepers is most likely related to the high level of specific IgG in this group.

Adult↗
PubMed1997

[Severe allergic-immunologic reactions].

Besides acute bronchial asthma IgE-mediated anaphylaxis is certainly the most important allergological emergency. Anaphylaxis is most often caused by drugs, foods and insect stings. The most relevant pathogenetic factors induced by allergy mediators are hypovolemia, bronchial obstruction and cardiac failure. Emergency treatment consists in intramuscular application of adrenaline and volume substitution by intravenous infusion. All patients should be hospitalized immediately and treated on an intensive care unit. Unfortunately, the subsequent consultation with an allergist does often not take place. This important preventive measure includes supply of instruction for allergen avoidance and of emergency medications. In anaphylaxis induced by insect stings specific immunotherapy should be started.

Anaphylaxis↗
PubMed1996

Fetal cells in maternal blood: recovery by charge flow separation.

Fetal blood cells can be recovered from the maternal circulation by charge flow separation (CFS), a method that obviates the risks associated with amniocentesis and chorionic villus sampling. By CFS, we processed blood samples from 13 women carrying male fetuses, 2 carrying fetuses with trisomy 21, and 1 who had delivered a stillborn infant with trisomy 18. On average more than 2000 fetal nucleated red blood cells were recovered per 20-ml sample of maternal blood. Recovery of fetal cells was confirmed by fluorescence in situ hybridization with probes for chromosomes Y, 18 and 21. After culturing of CFS-processed cells, amplification by the polymerase chain reaction revealed Y-chromosomal DNA in clones from four of six women bearing male fetuses, but not in clones from three women bearing female fetuses.

Cell Separation↗
PubMed1996

Colorectal intussusception: an unusual gastrointestinal complication of hereditary angioedema.

A 21-year-old man with a history of hereditary angioedema presented with protracted abdominal pain which failed to respond to infusion of C1 inhibitor concentrate. Evaluation by CT scan revealed extensive colorectal intussusception requiring surgical intervention. Under replacement therapy with C1 inhibitor concentrate, both the operation under general anesthesia and the postoperative phase were uneventful. The intraoperative examination suggested initiation of intussusception by local mucosal edema in the transverse colon.

Adult↗
PubMed1996

Influence of bee venom immunotherapy on degranulation and leukotriene generation in human blood basophils.

BACKGROUND: Rapid clinical tolerance can be induced over several hours by very fast bee venom immunotherapy (VIT) protocols. OBJECTIVE: To investigate the mechanisms underlying VIT we examined the changes of blood basophil responsiveness during VIT. METHODS: Seven bee venom allergic patients with a history of severe systemic reactions after a bee sting were investigated. A cumulative dose of 111.1 micrograms bee venom (BV) was administered sc over 3.5 h under intensive care conditions according to an ultra-rush protocol. The release of histamine and the formation of leukotrienes in response to BV, major BV allergen Phospholipase A2 (PLA), IgE receptor cross-linking with the use of monoclonal antibodies against IgE and IgE receptor, as well as IgE independent activation in response to C5a were determined in vitro before and after ultra-rush VIT. RESULTS: We demonstrated a decrease of total histamine in peripheral blood leucocytes just after VIT. Histamine release in response to all the stimuli used is not affected by ultra-rush VIT, if expressed as per cent release of total histamine. However, the absolute amount product released in response to stimulation was decreased, particularly with allergen (BV, PLA). We also found a significant reduction of LTC4 formation after VIT in samples stimulated with specific allergen (BV, PLA). CONCLUSION: Blood basophils are a target for VIT, which induces impaired release of both preformed and newly generated mediators. However, we believe the basic mechanisms of rapid clinical tolerance induced by ultra-rush VIT remain to be investigated.

Antibodies, Monoclonal↗
PubMed1995

Bee venom immunotherapy results in decrease of IL-4 and IL-5 and increase of IFN-gamma secretion in specific allergen-stimulated T cell cultures.

The mechanisms of bee venom immunotherapy (VIT) are largely unknown. The aim of this study was to follow the changes of T cell cytokine secretion during the course of VIT. Ten bee venom-allergic patients with a history of severe systemic reactions, positive skin tests, and bee venom (BV)-specific serum IgE Abs were treated as follows: on the first day, a cumulative dose of 111 micrograms, starting with 0.1 microgram, was administered s.c. under intensive care conditions. Further injections of 100 micrograms BV were given on day 7, day 21, and thereafter at intervals of 4 wk. Blood samples were obtained just before the initiation of VIT, after the last injection on the same day, and before the subsequent BV injections on days 7, 21, and 50 of VIT. Peripheral blood mononuclear cells (PBMC) were stimulated with phospholipase A (PLA), the major BV allergen, or with a control Ag tetanus toxoid (TT). Cytokine secretion was measured 24 h after restimulation of the cultures with solid-phase bound OKT3 F(ab')2 mAbs after 7 days of culture. In PLA-stimulated cultures, VIT resulted in decreased IL-4 and IL-5 and increased IFN-gamma secretion. In TT-stimulated cultures, we observed similar levels of cytokines before and during VIT. We conclude that ultra-rush VIT changes allergen-specific T cell reactivity.

Allergens↗