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M Focke

Publications and source records attributed to M Focke.

At least 37 records · Page 2Linked to original sources
PubMed2001

Identification of a Hevea brasiliensis latex manganese superoxide dismutase (Hev b 10) as a cross-reactive allergen.

BACKGROUND: Cross-reactive allergens play an increasingly important role in latex allergy in complicating both the diagnosis and time course of allergic symptoms. Manganese superoxide dismutase (MnSOD), a ubiquitous protein of prokaryotic and eukaryotic organisms, was described as a cross-reactive allergen in Aspergillus fumigatus. Little information is available on the importance of this pan-allergen in Hevea brasiliensis latex. The aim of this study was to clone and express MnSOD from H. brasiliensis latex, and to obtain the soluble and immunologically active recombinant allergen for diagnosis of latex allergy and to investigate possible cross-reactivities with the structurally related A. fumigatus and human MnSODs. METHODS: A complementary DNA coding for Hevea latex MnSOD was amplified by PCR. The recombinant protein was produced in Escherichia coli with an N-terminal hexahistidyl tag. Enzymatic activity of the recombinant protein was determined using an enzyme assay for SODs. IgE immunoblotting and IgE inhibition assays were performed to characterize the recombinant allergen and its cross-reactivity. RESULTS: A Hevea latex MnSOD consisting of 206 amino acid residues was cloned and expressed in E. coli. The allergen was designated Hev b 10. The recombinant protein was enzymatically active, indicating the correct folding of the protein. In immunoblots, latex- as well as A. fumigatus-allergic patients revealed IgE binding to recombinant (r)Hev b 10. Cross-reactivity to Asp f 6, the MnSOD from A. fumigatus, and human MnSOD was determined by inhibition of IgE binding to these MnSODs by rHev b 10. CONCLUSIONS: Hev b 10 is a new cross-reactive allergen of H. brasiliensis which belongs to the 'latex-mold' group of latex allergens. Furthermore, it is a candidate for primary sensitization in patients allergic to the pan-allergen MnSOD.

Allergens↗
PubMed2000

[Pili trianguli et canaliculi. A case report of uncombable hair in relation to atopic eczema and tooth anomalies].

We report on a child with pili trianguli et canaliculi. This hair shaft abnormality belongs to a heterogeneous group of diseases which are included under the synonym uncombable hair. The diagnosis was confirmed by scanning electron microscopy, revealing hair shafts with a characteristic longitudinal groove. In addition the girl suffered from atopic eczema and tooth anomalies. Our findings suggest that this disorder could represent a tricho-odontal subtype of ectodermal dysplasia.

Biotin↗
PubMed2000

Exposure to formaldehyde and phenol during an anatomy dissecting course: sensitizing potency of formaldehyde in medical students.

BACKGROUND: The sensitizing potency of formaldehyde and phenol during anatomy dissecting was investigated. The objective was to determine whether exposure induces specific IgE or IgG against formaldehyde-albumin or phenol-albumin. METHODS: In 27 medical students, specific IgE against formaldehyde-albumin by RAST plus ELISA and specific IgE against phenol-albumin by ELISA were assessed. In addition, specific IgG against formaldehyde-albumin was assessed in 23 students. Symptoms before and during dissecting were assessed, and indoor formaldehyde and phenol were measured. RESULTS: Mean indoor formaldehyde was 0.265 +/- 0.07 mg/m3, and mean indoor phenol was 4.65 +/- 2.96 mg/m3. Specific IgE/IgG against formaldehyde-albumin was not found at the beginning. Four students developed specific IgE against formaldehyde-albumin (RAST classes of > or =2.0), and all four also had specific IgE in the ELISA, but IgG against formaldehyde-albumin was not found. Specific IgE against phenol-albumin was not seen. Itch and paresthesia of the hands (P<0.00001), dizziness (P<0.008), burning eyes (P<0.01), headache, sneezing, epistaxis, gingival bleeding, oral or pharyngeal itch, and shortness of breath were experienced. CONCLUSIONS: Formaldehyde exposure during dissecting may induce specific IgE, but not IgG, against formaldehyde-albumin. Sensitization did not correlate with symptoms.

Adult↗
PubMed2000

Fern allergy.

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Allergens↗
PubMed2000

Ash (Fraxinus excelsior)-pollen allergy in central Europe: specific role of pollen panallergens and the major allergen of ash pollen, Fra e 1.

BACKGROUND: The role of ash (Fraxinus excelsior) pollen as a cause of spring pollinosis in central Europe has received little attention. It is not clear whether ash pollen is a primary cause of sensitization or whether it is implicated through cross-sensitization to other pollens. METHODS: Over a 22-month period, ash pollen was included in a screening series for inhalant allergies. Pollen data were documented from 1976 through 1999. The frequency of IgE-binding to the ash-specific allergen Fra e 1 and pollen panallergens, respectively, was compared by Western blot between mono- (n = 6), oligo- (n = 16), and polysensitized (n=25) patients. RESULTS: Of 5,416 consecutive patients sensitized to any pollen, 920 (17.6%) had a positive skin prick test to ash. Total pollen counts varied extensively between years (229-5,351) as did peak concentrations (23-837 grains/m3/24 h). Western blotting revealed Fra e 1 sensitization in 100% of monosensitized, 93% of oligosensitized, but only 44% of polysensitized patients. IgE against profilins (Fra e 2), Ca-binding proteins (Fra e 3), and carbohydrate epitopes in the three groups was found in 0/0/17%, 0/19/31%, and 32/72/60%, respectively. At least 50% of sera from patients with Fra e 1 sensitization did not bind with the protein in Western blots under reducing conditions. CONCLUSIONS: Ash pollen should be considered a relevant factor and distinct entity in spring pollinosis. In all, only 20% of positive skin tests to ash appear to result from cross-sensitization to pollen panallergens.

Allergens↗
PubMed2000

Understanding in vivo carbon precursor supply for fatty acid synthesis in leaf tissue.

The principal supply of carbon precursors for fatty acid synthesis in leaf tissue has been a much debated topic, with some experiments suggesting a direct supply from the C3 products of photosynthetic carbon fixation and colleagues suggesting the utilization of free acetate (for which concentrations in leaves in the range of 0.05-1.4 mM have been reported). To address this issue we first reassessed the in vivo rate of fatty acid synthesis using a new method, that of [13C]carbon dioxide labeling of intact Arabidopsis plants with the subsequent analysis of fatty acids by gas chromatography-mass spectrometry (GC-MS). This method gave an average value of 2.3 mmoles carbon atoms h-1 mg chlorophyll-1 for photosynthetic tissues. The method was extended by isotopic dilution analysis to measure the rate of fatty acid synthesis in the dark. There was negligible fatty acid synthesis (< 5% of the rate in the light) in the dark. In addition, the method allowed an estimate of the absolute rate of fatty acid degradation of about 4% of the total fatty acid content per day. With the in vivo rate of fatty acid synthesis in the light defined, if the bulk tissue acetate concentration available for fatty acid synthesis is 1 mM, this acetate pool can sustain fatty acid synthesis for approximately 60 min. When the leaves of Arabidopsis, barley and pea were given a 5 min pulse of [14C]carbon dioxide, the label rapidly appeared in fatty acids with a lag phase of less than 2-3 min. Continuous labeling with [14C]carbon dioxide, for up to 1 h, showed a similar result. Furthermore, 14C-label in free acetate was less than 5% of that in fatty acids. In conclusion, these data suggest that either the bulk pool of acetate is not involved in fatty acid synthesis or the concentration of acetate must be less than 0.05 mM under strong illumination.

Acetic Acid↗
PubMed2000

Fatty acid synthesis: from CO2 to functional genomics.

For over 25 years there has been uncertainty over the pathway from CO(2) to acetyl-CoA in chloroplasts. On the one hand, free acetate is the most effective substrate for fatty acid synthesis by isolated chloroplasts, and free acetate concentrations reported in leaf tissue (0.1-1 mM) appear adequate to saturate fatty acid synthase. On the other hand, a clear mechanism to generate sufficient free acetate for fatty acid synthesis is not established and direct production of acetyl-CoA from pyruvate by a plastid pyruvate dehydrogenase seems a more simple and direct path. We have re-examined this question and attempted to distinguish between the alternatives. The kinetics of (13)CO(2) and (14)CO(2) movement into fatty acids and the absolute rate of fatty acid synthesis in leaves was determined in light and dark. Because administered (14)C appears in fatty acids within < 2-3 min our results are inconsistent with a large pool of free acetate as an intermediate in leaf fatty acid synthesis. In addition, these studies provide an estimate of the turnover rate of fatty acid in leaves. Studies similar to the above are more complex in seeds, and some questions about the regulation of plant lipid metabolism seem difficult to solve using conventional biochemical or molecular approaches. For example, we have little understanding of why or how some seeds produce >50% oil whereas other seeds store largely carbohydrate or protein. Major control over complex plant biochemical pathways may only become possible by understanding regulatory networks which provide 'global' control over these pathways. To begin to discover such networks and provide a broad analysis of gene expression in developing oilseeds, we have produced microarrays that display approx. 5000 seed-expressed Arabidopsis genes. Sensitivity of the arrays was 1-2 copies of mRNA/cell. The arrays have been hybridized with probes derived from seeds, leaves and roots, and analysis of expression ratios between the different tissues has allowed the tissue-specific expression patterns of many hundreds of genes to be described for the first time. Approx. 10% of the genes were expressed at ratios > or = 10-fold higher in seeds than in leaves or roots. Included in this list are a large number of proteins of unknown function, and potential regulatory factors such as protein kinases, phosphatases and transcription factors. The arrays were also found to be useful for analysis of Brassica seeds.

Acetyl Coenzyme A↗
PubMed1999

Molecular and immunologic characterization of new isoforms of the Hevea brasiliensis latex allergen hev b 7: evidence of no cross-reactivity between hev b 7 isoforms and potato patatin and proteins from avocado and banana.

BACKGROUND: Hev b 7 is a Hevea brasiliensis latex allergen with sequence identities of 39% to 42% to patatins recently identified as potato allergens. The complementary DNAs encoding 2 different Hev b 7 isoforms were previously reported. OBJECTIVE: The aim of this study was to determine the sequence variation of Hev b 7 and to compare the IgE reactivity of individual isoforms in vitro and in vivo. A further objective was to evaluate possible cross-reactivities between Hev b 7 and patatins and proteins from banana and avocado. METHODS: An H brasiliensis lambda ZAP complementary DNA (cDNA) library was screened with use of a Hev b 7 cDNA probe. Four Hev b 7 isoforms were produced in recombinant form and their IgE-binding capacities were compared. IgE immunoblot inhibitions and ELISA inhibition assays were used to investigate the possible cross-reactivity between Hev b 7 and recombinant potato patatin and proteins from avocado and banana. RESULTS: Two new isoforms, S2 and D2, were identified by sequencing 32 cDNA clones with full-length coding regions. All 4 recombinant isoforms displayed esterase activity and identical IgE-binding capacities. The new isoforms S2 and D2 were evaluated in skin prick tests and provoked responses equivalent to natural Hev b 7. No cross-reactivity was observed between Hev b 7 isoforms and potato patatin and proteins from avocado and banana. CONCLUSIONS: All 4 recombinant Hev b 7 isoforms have equivalent IgE-binding capacity and therefore represent suitable reagents for the development of in vitro and in vivo diagnostic tests. Hev b 7, patatins, and their homologs appear not to contribute to cross-reactivity in the latex-fruit syndrome.

Adult↗
PubMed1998

Identification of allergens in oilseed rape (Brassica napus) pollen.

BACKGROUND: Pollen from oilseed rape (OSR), Brassica napus, an increasingly cultivated oilplant from the Brassicaceae, has been recognized as a potential cause of allergic sensitization. Allergens have been hardly investigated. METHODS: We characterized IgE binding proteins in OSR pollen by immunoblot, immunoblot inhibition and specific monoclonal antibodies using sera from 89 patients sensitized to OSR. RESULTS: Two low-molecular-weight allergens of 6/8 kD and 14 kD as well as a high molecular-weight cluster (27-69 kD) comprising six cross-reactive peptides could be identified. The three allergens were recognized by 50, 34 and 80% of patients, respectively. Immunoblot IgE binding to OSR could be totally inhibited by rye pollen and moderately by birch pollen (6/8 and 14 kD) while mugwort had little effect. An anti-profilin-specific monoclonal antibody bound specifically to a 14-kD protein in OSR. Binding to the 6/8-kD rape allergen could be effectively inhibited by rAln g 2, a calcium-binding protein from alder. Periodate treatment led to a significant reduction in IgE binding to the 27 to 69-kD OSR allergens indicating that carbohydrate determinants are involved in IgE binding. OSR proteins were capable to quench IgE binding to timothy grass pollen proteins of >/=60 kD suggesting that grass pollen group 4 allergens cross-react with the 27 to 69-kD cluster in OSR. CONCLUSIONS: The data demonstrate that OSR pollen is allergenic and indicate that the identified allergens represent cross-reacting homologues of well-known pollen allergens, i.e. calcium-binding proteins, profilins, and high-molecular-weight glycoproteins. Via cross-reactivity, exposure to OSR pollen may be a prolonging and aggravating factor in underlying birch and grass pollen allergy.

Allergens↗
PubMed1997

Incorporation of 1-deoxy-D-xylulose into isoprene and phytol by higher plants and algae.

In further substantiating the novel mevalonate-independent pathway for isoprenoid biosynthesis, which generates isopentenyl diphosphate (IPP) via 1-deoxy-D-xylulose-5-phosphate, labeling experiments with 1-[2H(1)]deoxy-D-xylulose were performed with various higher plants and algae: efficient incorporation was observed into isoprene emitted by Populus, Chelidonium, and Salix, into the phytol moiety of chlorophylls in a red alga (Cyanidium), in two green algae (Scenedesmus, Chlamydomonas), and a higher plant (Lemna). By contrast, 13C-mevalonate applied was incorporated into isoprene and phytol to a much lower extent or not at all. This demonstrates that this '1-deoxy-D-xylulose-5-phosphate pathway' for biosynthesis of plastidic isoprenoids is widely distributed in photosynthetic organisms.

Butadienes↗