Post-translational modifications influence IgE reactivity to the major allergen Phl p 1 of timothy grass pollen

BACKGROUND

Grass group I consists of very potent allergenic components which are found in the pollen of all temperate grasses. Several post-translational modifications are predicted from the cDNA data.

OBJECTIVE

The aim of this study was to identify sequential IgE-binding sites on the allergen Phl p 1 and to determine their influence on IgE reactivity.

METHODS

Based on cDNA data and microsequencing results we synthesized overlapping decapeptides covering the complete Phl p 1 molecule and tested them for immunological reactivity by means of the PEPSCAN technique. In a dot test we determined the frequency of IgE reactivities to post-translationally modified structures (hydroxylated proline residues, carbohydrate structure, and disulphide formations).

RESULTS

Screening by overlapping peptides demonstrated an IgE binding site on the 10 N-terminal amino acids. Comprehensive studies showed that the two hydroxyproline residues of the native Phl p 1 allergen (at positions 5 and 8) and the N-glycan (at position 9) can result in an increased IgE reactivity; 3.3% of the sera exclusively bound to the hydroxyproline bearing peptide, while only 0.4% bound to the proline containing peptide. With regard to glycosylation, we estimated that 20% of sera recognized protein and carbohydrate epitopes, while one serum exclusively bound to the glycan. The formation of disulphide bonds has no detectable effect on the IgE reactivity to Phl p 1.

CONCLUSION

Our results indicate that the post-translational modifications, the carbohydrate structure and the hydroxylation of proline residues, can enhance the IgE reactivity of Phl p 1.

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.

Functional involvement of polypyrimidine tract-binding protein in translation initiation complexes with the internal ribosome entry site of foot-and-mouth disease virus

The synthesis of picornavirus polyproteins is initiated cap independently far downstream from the 5' end of the viral RNA at the internal ribosome entry site (IRES). The cellular polypyrimidine tract-binding protein (PTB) binds to the IRES of foot-and-mouth disease virus (FMDV). In this study, we demonstrate that PTB is a component of 48S and 80S ribosomal initiation complexes formed with FMDV IRES RNA. The incorporation of PTB into these initiation complexes is dependent on the entry of the IRES RNA, since PTB and IRES RNA can be enriched in parallel either in 48S or 80S ribosomal complexes by stage-specific inhibitors of translation initiation. The formation of the ribosomal initiation complexes with the IRES occurs slowly, is temperature dependent, and correlates with the incorporation of PTB into these complexes. In a first step, PTB binds to the IRES, and then the small ribosomal subunit encounters this PTB-IRES complex. Mutations in the major PTB-binding site interfere simultaneously with the formation of initiation complexes, translation efficiency, and PTB cross-linking. PTB stimulates translation directed by the FMDV IRES in a rabbit reticulocyte lysate depleted of internal PTB, and the efficiency of translation can be restored to the original level by the addition of PTB. These results indicate that PTB plays an important role in the formation of initiation complexes with FMDV IRES RNA and in stimulation of internal translation initiation with this picornavirus.

The functional phenotype of the primitive plasma cell in patients with multiple myeloma correlates with the clinical state

The malignant plasma cells from patients with multiple myeloma display considerable phenotypic heterogeneity. All plasma cells express high intensity CD38 (CD38++), cytoplasmic immunoglobulin and either kappa or lambda light chains. Subpopulations of mature (CD45-), immature (CD45+) and primitive (CD45++, CD19+) plasma cells can be defined but little is known about the functional differences and clinical significance of these subpopulations. Three colour flow cytometry and permeabilisation was used to determine the expression of functionally important antigens in plasma cell subpopulations. These antigens included the labelling index (LI, bromodeoxyuridine), number of nucleoside transporter per cell, p-glycoprotein (JSB-1), and oncoprotein expression (c-myc, c-fos, c-neu, bcl-2, p-ras, p53m, p-53w, and Rb). In progressive disease there was an increase in the absolute number but not the percentage of CD45++ plasma cells. There was a significant difference in the mean LI of the CD38++, CD45++ population in progressive disease compared with stable disease (9.2% vs 2.2%; z = 19.9, p < 0.001). The LI of CD45++ cells ranged up to 45% and provided a better correlation with disease status than the LI of the total cell population. Any increase in nucleoside transporters or p-glycoprotein expression was almost entirely attributable to an increase in the primitive plasma cell population. In 96% (n = 28) of samples from patients in progressive disease there was at least one abnormality in the functional phenotype of the primitive plasma cells. This is in contrast with 44% of samples from patients in stable disease (n = 58). These studies suggest that the functional phenotype of the primitive plasma cell determines the clinical phenotype of patients with myeloma.

Are speech perception deficits associated with developmental dyslexia?

Phonological awareness and phoneme identification tasks were administered to dyslexic children and both chronological age (CA) and reading-level (RL) comparison groups. Dyslexic children showed less sharply defined categorical perception of a bath-path continuum varying voice onset time when compared to the CA but not the RL group. The dyslexic children were divided into two subgroups based on phoneme awareness. Dyslexics with low phonemic awareness made poorer /b/-/p/ distinctions than both CA and RL groups, but dyslexics with normal phonemic awareness did not. Examination of individual profiles revealed that the majority of subjects in each group exhibited normal categorical perception. However, 7 of 25 dyslexics had abnormal identification functions, compared to 1 subject in the CA group and 3 in the RL group. The results suggest that some dyslexic children have a perceptual deficit that may interfere with processing of phonological information. Speech perception difficulties may also be partially related to reading experience.

A family with chronic haemolysis and selective accumulation of erythrocyte CDP-choline

In this paper, we report a family with compensated chronic haemolysis where the only erythrocyte abnormality detected was an increased level of erythrocyte CDP-choline. Using 31P-NMR spectroscopy and enzymatic analysis the possibility of a pyrimidine 5'-nucleotidase deficiency was excluded. Thus, this family represents the first evidence for a hereditary haemolytic anaemia where the inferred enzymatic defect is located to choline phosphotransferase, the enzyme catalysing the final step in lecithin synthesis. The family history indicates an autosomal dominant mode of transmission with incomplete penetrance.

Investigation of different recombinant isoforms of grass group-V allergens (timothy grass pollen) isolated by low-stringency cDNA hybridization--antibody binding capacity and allergenic activity

A cDNA library of timothy grass pollen was screened for homologous isoforms of major group-V allergens by low stringency hybridization with a Phl p 5 (Phleum pratense) probe. After restriction analysis of the 40 clones obtained, 17 were selected for cDNA sequencing. Of these clones, two were unrelated to group-V allergens, six showed high similarity but an incomplete open reading frame and nine had high similarity with a complete open reading frame. Comparison of deduced amino acids of ten complete cDNA clones confirmed the presence of two major isoforms, a and b. Within these two subgroups, only minor sequence variations were observed. Eight isoforms were expressed in Escherichia coli K12 and purified to homogeneity. Although the subgroups a and b could be distinguished by their molecular masses and by binding constants towards monoclonal antibodies, all isoforms turned out to be biochemically similar. Ribonuclease activity as a marker for the biological function of group-V allergens was shown to be in the same range for both subgroups. Analysis of allergenic B-cell responses towards the isoforms in 26 grass pollen allergic patients revealed that the IgE reactivities to the different isoforms were identical for each individual. IgE reactivities and allergenic activities of three isovariants and an allergen of a different group were compared in a selected group of four grass pollen allergic patients by immunoblot, histamine-release and skin-prick tests. The IgE reactivity does not necessarily mirror the allergenic activity of the single molecule, and the variability of allergenic activity between the isovariants does not, in every case, depend on the structural differences of these allergens. We conclude that group-V isoallergens in grass pollen, although they can be structurally different, induce a similar B-cell response but can show variable allergenic activity. Thus, the most allergenic isoform of each important group of allergens should be sufficient for the diagnosis of type-I allergy. Whether the isoallergenic variation has any significant influence on the outcome of immunotherapy in allergic disease still has to be elucidated.

Mapping of IgE-binding epitopes on the recombinant major group I allergen of velvet grass pollen, rHol l 1

BACKGROUND

New and more successful approaches to diagnosis and therapy of allergic diseases require a more subtle understanding of the structure and the epitopes on the allergen molecule.

OBJECTIVE

This study was done to obtain more information on the structure and the IgE-binding epitopes of a major allergen of velvet grass pollen, Hol l 1.

METHODS

We cloned Hol l 1 from a complementary DNA library and performed B-cell epitope mapping with 21 recombinant fragments expressed as fusion proteins in Escherichia coli. The fragments were analyzed by Western blotting with sera from 50 different patients.

RESULTS

The patients' sera individually recognized at least four different IgE-binding regions (amino acids 1 to 27, 61 to 76, 84 to 105, and 158 to 240). According to their binding patterns with these epitopes, they were divided into five groups. Most sera (92%) bound to the C-terminal peptide (158 to 240), which consists of more than 80 amino acids, whereas there was virtually no binding to smaller fragments covering this region. In contrast to the C-terminal peptide, the IgE-binding peptides on the N terminus and on the middle region of the molecule were of a smaller size (15 to 30 amino acids).

CONCLUSIONS

The major group I allergen of velvet grass bears at least four different IgE-binding epitopes, which were individually recognized by sera from different patients. The C terminus represents the major IgE-binding region and contains at least one discontinuous IgE-binding epitope, whereas the N terminus and middle region of Hol l 1 seem to contain continuous IgE-binding epitopes.

Expression of the Solfolobus acidocaldarius Rieske iron sulfur protein II (SOXF) with the correctly inserted [2FE-2S] cluster in Escherichia coli

The Rieske protein II (Schmidt et al., 1996, FEBS Lett. 388, 43-46) from the thermoacidophilic crenarcheon Sulfolobus acidocaldarius (DSM 639) was expressed in E. coli cells. The full length protein was strictly bound to the E. coli membranes and could only be removed by detergent treatment indicating the presence of a membrane anchor. The iron sulfur cluster was correctly inserted into a fraction of the full length protein and much more effectively into a soluble form created by the deletion of the 45 N-terminal amino acids. The soluble form of the protein displayed the typical spectroscopic properties of a respiratory Rieske protein. The midpoint potential was +375 mV determined by CD redox potentiometry. The presented data demonstrate that the structure of the recombinant protein is very similar or identical to the authentic protein making this a powerful model system for the studies of Rieske proteins by site directed mutagenesis.

Comparison of natural and recombinant isoforms of grass pollen allergens

More than 95% of grass pollen allergic patients possess IgE antibodies against grass group I, a heterogeneous group of glycoproteins found in all temperate grasses. We studied the structural variability of the group I allergens in single species and among different grasses. By 2-DE blotting using patients' IgE and monoclonal antibodies, we detected IgE-reactive isoforms with molecular masses between 32 and 37 kDa and focusing in a wide pI ranging from 4.7 to 7.6. While the group I allergens of timothy grass (Phl p 1) were composed of 37 and 35 kDa components, only single isoforms were found for ryegrass (Lol p 1) and velvet grass (Hol l 1): 32 and 34 kDa, respectively. By N-terminal microsequencing we determined single amino acid substitutions in different-sized group I allergens. The post-translational modifications (one N-glycosylation site, two hydroxylated proline residues and seven cysteine residues for potential disulfide formations), which contribute to IgE reactivity, were identical in all. From the cDNA sequences we deduced protein sequence homologies > 90%, a result which might explain the high IgE cross-reactivity among the grasses. In order to test whether recombinant group I grass allergens can act as substitutes for the natural forms, we expressed rPhl p 1 in E. coli and in P. pasteuris. 2-DE immunoblotting again demonstrated a microheterogeneity in molecular mass and pI. While the E. coli products were free from post-translational modifications, rPhl p 1 from Pichia is a heterogeneous glycoprotein fraction with a carbohydrate content of about 15%. This rPhl p 1 is hyperglycosylated compared to the nPhl p 1, which only has a 5% carbohydrate content.

The signal recognition particle receptor alpha subunit of the hyperthermophilic archaeon Acidianus ambivalens exhibits an intrinsic GTP-hydrolyzing activity

Two adjacent genes of the acidophilic and hyperthermophilic crenarchaeon Acidianus ambivalens were cloned and sequenced. The 1.6 kb genomic nucleotide sequence under investigation consists of the 1.12 kb SRa gene encoding the putative signal recognition particle receptor alpha subunit (SR alpha, 42.2 kDa) and the 186 basepair secE gene coding for the putative secretory component secE subunit (6800 Da). The SR alpha protein is structured by three distinct regions: the N-terminal hydrophilic H-region, the following X-region and the C-terminal GTP-binding domain. A polyclonal anti-E. coli lacZ/A. ambivalens SR alpha antiserum detects a 51 kDa cell protein (p51) on immunoblots. Proteolysis of the recombinant SR alpha protein by Proteinase K produces a 31.6 kDa protease-resistant protein fragment comprising X-region and G-domain. The protein binds tightly to the GTP-agarose affinity matrix in a temperature-dependent manner. It hydrolyzes GTP readily at higher temperatures only in the presence of Mg2+. Point mutations (T326N) and (D329A) in the G-4 element of A. ambivalens SR alpha G-domain diminish the GTPase activity significantly. In contrast, the deletion mutant protein SR alpha (delta1-92) lacking the hydrophilic H-region displays a higher GTP-hydrolyzing activity when compared to the unmodified recombinant protein. Addition of GDP greatly inhibits GTP hydrolysis in mutant and unmodified A. ambivalens SR alpha.

Human vascular smooth muscle cells express interleukin-1beta-converting enzyme (ICE), but inhibit processing of the interleukin-1beta precursor by ICE

Local immunoregulatory processes during normal vascular biology or pathogenesis are mediated in part by the production of and response to cytokines by vessel wall cells. Among these cytokines interleukin (IL)-1 is considered to be of major importance. Although vascular smooth muscle (SMC) and endothelial cells (EC) expressed both IL-1alpha and IL-1beta as cell-associated, 33-kilodalton (kD) precursors, SMC neither contained detectable mature IL-1beta, nor processed recombinant IL-1beta precursor into its mature 17-kD form. Thus, we investigated the expression and function of IL-1beta-converting enzyme (ICE) in vascular cells. We demonstrate in processing experiments with recombinant IL-1 precursor molecules that EC processed IL-1beta, in contrast to SMC. Despite the failure of SMC to process IL-1beta, these cells expressed ICE mRNA, immunoreactive ICE protein, and the expected IL-1beta nucleotide sequence. The lack of processing was explained by our finding that extracts of SMC specifically and concentration dependently blocked processing of IL-1beta precursor by recombinant or native ICE. The initial biochemical characterization of the inhibitory activity showed that it is heat-labile, has a molecular size of 50-100 kD, and is associated to the cell membrane compartment. Inhibition of processing, i.e., activation of IL-1beta precursor by SMC may constitute a novel regulatory mechanism during normal vascular biology or pathogenesis of vascular diseases.

The terminal quinol oxidase of the hyperthermophilic archaeon Acidianus ambivalens exhibits a novel subunit structure and gene organization

A terminal quinol oxidase has been isolated from the plasma membrane of the crenarchaeon Acidianus ambivalens (DSM 3772) (formerly Desulfurolobus ambivalens), cloned, and sequenced. The detergent-solubilized complex oxidizes caldariella quinol at high rates and is completely inhibited by cyanide and by quinolone analogs, potent inhibitors of quinol oxidases. It is composed of at least five different subunits of 64.9, 38, 20.4, 18.8, and 7.2 kDa; their genes are located in two different operons. doxB, the gene for subunit I, is located together with doxC and two additional small open reading frames (doxE and doxF) in an operon with a complex transcription pattern. Two other genes of the oxidase complex (doxD and doxA) are located in a different operon and are cotranscribed into a common 1.2-kb mRNA. Both operons exist in duplicate on the genome of A. ambivalens. Only subunit I exhibits clear homology to other members of the superfamily of respiratory heme-copper oxidases; however, it reveals 14 transmembrane helices. In contrast, the composition of the accessory proteins is highly unusual; none is homologous to any known accessory protein of cytochrome oxidases, nor do homologs exist in the databases. DoxA is classified as a subunit II equivalent only by analogy of molecular size and hydrophobicity pattern to corresponding polypeptides of other oxidases. Multiple alignments and phylogenetic analysis of the heme-bearing subunit I (DoxB) locate this oxidase at the bottom of the phylogenetic tree, in the branch of heme-copper oxidases recently suggested to be incapable of superstoichiometric proton pumping. This finding is corroborated by lack of the essential amino acid residues delineating the putative H+-pumping channel. It is therefore concluded that A. ambivalens copes with its strongly acidic environment simply by an extreme turnover of its terminal oxidase, generating a proton gradient only by chemical charge separation.

IgE binding to a new cross-reactive structure: a 35 kDa protein in birch pollen, exotic fruit and other plant foods

Food allergies in birch pollen allergic patients have been shown to be due to cross-reactivities of specific IgE antibodies which are directed against birch pollen allergens with related proteins in fruit, nuts and vegetables. We identified a new cross-reactive structure of 35 kDa in birch pollen and some plant food extracts by Enzyme Allergosorbent Test (EAST) and immunoblot inhibition studies. The 35 kDa birch pollen protein is a minor allergen to which approximately 10-15% of birch pollen allergic individuals have specific IgE. Our data demonstrate that there is cross-reactivity of this protein with proteins of comparable size from lychee, mango, banana, orange, apple, pear and carrot. While the 35 kDa protein is immunologically independent of the major birch pollen allergen Bet v 1, we also observed IgE binding to a 34 kDa structure which appears to be a Bet v 1 dimer.

Crystallization and preliminary diffraction data of a major pollen allergen. Crystal growth separates a low molecular weight form with elevated biological activity

Group V major allergen Phl p 5b of timothy grass pollen induces allergic rhinitis and bronchial asthma in 90% of grass pollen-allergic patients. In addition to its allergenicity ribonuclease activity has recently been attributed to this 29-kDa protein. The allergen was expressed in Escherichia coli and subsequently purified. Spontaneous conversion of these preparations to a mixture of various forms with molecular sizes between 10 and 29 kDa was consistently observed. Surprisingly, crystals could be grown from this heterogenous preparation. Single crystals, redissolved and analyzed by SDS-polyacrylamide gel electrophoresis and immunoblot, yielded one distinct low molecular weight protein, which was identified by amino acid sequencing as the C-terminal 13-kDa portion of the allergen. Histamine release assays with single crystal solutions using basophils of an allergic patient demonstrated allergenicity comparable with that of the holo-allergen. By contrast, RNase activity of the crystallized C-terminal form was 23 times higher than that of the full-length parent allergen. Crystals were used to collect preliminary diffraction data; the space group was evaluated to I4122 with cell dimensions of a = 87.7 A, b = 87.7 A, and c = 59.6 A. We conclude that preferential crystal growth of the 13-kDa form is indicative of a compact conformation of this particular C-terminal portion of the allergen. Thus, we show here that protein crystallization is not only a prerequisite for structural analyses, but it also can provide a unique separation technique to localize the functional domain of a major allergen.

Ubiquitous structures responsible for IgE cross-reactivity between tomato fruit and grass pollen allergens

The simultaneous presence of IgE reactivity to tomato fruit and grass pollen allergens is evident in many patients with allergy and may be caused by cross-reactivity. Using sera from polysensitized patients with a positive enzyme allergosorbent test (EAST) result (score > 2), we tested reactivity to both allergen sources. IgE reactivity against both extracts was demonstrated in eight serum samples, and cross-reactivity was confirmed by the EAST inhibition assay. The structures responsible for this cross-reactivity were identified by Western blotting: five of the eight sera demonstrated a 16 kd protein in both extracts, which was identified as profilin. Additionally, seven of the eight sera showed IgE binding to epitopes on carbohydrate moieties, which contained alpha 1, 3 fucosylations. To determine the allergens of tomato fruit extract, we performed two-dimensional polyacrylamide gel electrophoresis blotting. We were able to demonstrate one highly concentrated and about 20 weaker proteins possessing terminal fucose residues. These are similarly found in grass pollen extracts. It is therefore postulated that the cross-reactivity is affected by profilins and similar carbohydrate determinants. If carbohydrate structures can provoke IgE cross-reactivity between phylogenetically distant species, such structures may play an important role in sensitization and mediator release. The ubiquitous nature of the IgE-binding determinants was studied by additional EAST inhibition tests with tomato allergen disks and extract from birch pollen, mugwort pollen, apple, and celery, leading to significant inhibitions among all these allergen sources. Epitopes exclusive to grass pollen and tomato have not been detected.

Identification and characterization of the major allergens of velvet grass (Holcus lanatus), Hol l 1 and Hol l 5

Although extract of velvet grass pollen is an important ingredient of commercial allergen extracts for immunotherapy, it is not defined concerning its major allergenic components. We have investigated the extract of velvet grass pollen by Western blotting using the sera of 97 patients and identified two major allergens of 34 and 30 kD. By two-dimensional immunoblotting with monoclonal antibodies and lectins, and by biochemical analysis the 34-kD protein was identified as a group I grass pollen allergen and the 30-kD protein as a group V grass pollen allergen. According to the nomenclature for grass pollen allergens we designated these allergens Hol l 1 and Hol l 5, respectively. Fragmentation of the velvet grass pollen extract by CNBr provided the first information on the localization of IgE binding epitopes on these two allergens. With Hol l 1 and Hol l 5 we identified two important components of commercial allergen extracts.

Pseudohomophone effects and models of word recognition

Two experiments examined factors that influence the processing of pseudohomophones (nonwords such as brone or joap, which sound like words) and nonpseudohomophones (such as brone and joap, which do not sound like words). In Experiment 1, pseudohomophones yielded faster naming latencies and slower lexical-decision latencies than did nonpseudohomophones, replicating results of R. S. McCann and D. Besner (1987) and R. S. McCann, D. Besner, and E. Davelaar (1988). The magnitude of the effect was related to subjects' speed in lexical decision but not naming. In Experiment 2, both immediate and delayed naming conditions were used. There was again a significant pseudohomophone effect that did not change in magnitude across conditions. These results indicate that pseudohomophone effects in the lexical-decision and naming tasks have different bases. In lexical decision, they reflect the pseudohomophone's activation of phonological and semantic information associated with words. In naming, they reflect differences in ease of articulating familiar versus unfamiliar pronunciations. Implications of these results concerning models of word recognition are discussed, focusing on how pseudohomophone effects can arise within models that do not incorporate word-specific representations, such as the M. S. Seidenberg and J. L. McClelland (1989) model.

The labelling index of primitive plasma cells determines the clinical behaviour of patients with myelomatosis

For patients with multiple myeloma the most important laboratory correlate of prognosis and disease activity is the bromodeoxyuridine (BrdUrd) plasma cell labelling index (LI). However, the traditional immunofluorescent microscope LI technique, like other manual enumeration assays, can suffer from poor precision and accuracy. In this study the LI of different subpopulations of plasma cells (CD38++) as determined by flow cytometry was correlated with disease state. The mean LI of the total CD38++ population was significantly higher (2.7 +/- 0.4%) than the LI determined by the traditional slide technique (0.6 +/- 0.1%) for 65 samples tested. Primitive plasma cells (CD38++, CD45++) had a higher labelling index than mature plasma cells (CD38++, CD45-) (7.0 +/- 1.3% v 1.8% +/- 0.3%) and in one patient the LI of the primitive plasma cells was 46%. In addition, the LI of the mature plasma cells was lower than the total plasma cell population. As expected, there was a significant difference between the LI of patients in plateau phase and progressive disease but this difference was greatest when the LI of the primitive plasma cells was studied (9.2 +/- 2.9% v 2.2 +/- 0.7%; z = 19.9, P < 0.001). This study has raised some concerns about the sensitivity and accuracy of the traditional labelling index and has shown that the increased LI associated with progressive disease is almost entirely attributable to an increase in the LI of the primitive plasma cell subpopulation and that the LI of primitive plasma cells provides a more clinically significant correlation with disease status than the traditional assay.

Selective growth of freshly isolated human breast epithelial cells cultured at low concentrations in the presence or absence of bone marrow cells

In this study, we show that conditions previously found to promote the selective growth of human breast epithelial cells (HBEC) in serum-free primary cultures established from normal or malignant tissue can be extended to cultures initiated at low seeding densities (< 5000 cells/cm2). The epithelial nature of the cells produced was documented by their positive staining with antibodies specific for keratins 8, 14, and 18, and 2 antibodies that recognize epithelial-specific antigens (Ber-EP4 and HB8630). HBEC growth was not affected, either positively or negatively, by the use of a medium containing a combination of fetal calf and horse serum, which promotes the growth of many types of stromal cells and associated hematopoietic precursors, or by the inclusion in the initial cell suspension of marrow cells at HBEC to marrow cell ratios typical of bone marrow samples from patients with metastatic breast cancer. The presence of fibroblast feeders from a variety of sources enhanced the growth of HBEC to different degrees. In cultures initiated with low numbers of cells obtained from samples of breast carcinoma, HBEC growth was generally reduced by comparison to cultures of normal HBEC. With the detection methods used, it was not possible to determine the extent to which this decreased growth was due to a reduced frequency of malignant HBEC with in vitro precursor activity, or the presence of reduced numbers of residual normal HBEC precursors, or both. However, preliminary data indicate that this approach also allows the detection of some breast carcinoma cells with proliferative ability that are present in the marrow or pleural effusions of some breast cancer patients. These studies demonstrate the feasibility of detecting normal and malignant HBEC with growth potential when these are cultured at low density and/or as rare contaminants of marrow cell suspensions, and provide a starting point for their further characterization.

Isolation, characterization and crystallization of an iron-superoxide dismutase from the crenarchaeon Sulfolobus acidocaldarius

An iron containing superoxide dismutase from the cytosol of the thermoacidophilic crenarchaeon Sulfolobus acidocaldarius (DSM 639) has been purified to electrophoretic homogeneity. It comprises at least 11% of the cytosolic protein. The isolated protein consists of two identical subunits with an apparent molecular mass of 22.4 kDa. It contains one iron atom per dimer. The protein shows the typical EPR spectrum of a S = 3/2, rhombic high-spin iron center. It is extremely resistant against thermal and chemical denaturation. Simultaneous treatment with heat and detergent resulted in the conversion into a more active tetrameric form. Similar enzymes appear to be present in the cytosol of other members of the Sulfolobaceae. The dimeric form of the protein from S. acidocaldarius has been crystallized.

Metabolism of neuropeptide Y and calcitonin gene-related peptide by cultivated neurons and glial cells

Neuropeptide Y and calcitonin gene-related peptide are abundant neuropeptides in the mammalian central and peripheral nervous systems. Their enzymatic degradation by cultivated neurons, astrocytes, and microglia, as well as by purified urokinase-type plasminogen activator, plasmin, thrombin, and trypsin, was investigated in an in vitro approach to elucidate the role of matrix-degrading serine proteinases for inactivation of neuropeptides, especially those of higher amino acid chain length, in the brain. Astrocytes were almost unable to catabolize the peptides. Cultivated neurons and microglia digested neuropeptide Y through cleavage after Arg19, Arg25, Arg33, and Arg35, calcitonin gene-related peptide was cleaved after Arg11 and Arg18. The same cleavage pattern was observed, when neuropeptide Y and calcitonin gene-related peptide were degraded by purified urokinase-type plasminogen activator, plasmin, thrombin, and trypsin. For further characterization of the neuropeptide-degrading serine proteinase activities from cell cultures, urokinase-type plasminogen activator was identified on microglia by immunostaining, whereas tissue-type plasminogen activator mRNA occurred in neurons and astrocytes, but not in microglia. The data are consistent with the possibility that the neuropeptide-degrading serine proteinase activity on neurons and microglia is due to a mixture of plasmin and plasminogen activator activities.

On the bases of two subtypes of developmental [corrected] dyslexia

This study examined whether there are different subtypes of developmental dyslexia. The subjects were 51 dyslexic children (reading below the 30th percentile in isolated word recognition), 51 age-matched normal readers, and 27 younger normal readers who scored in the same range as the dyslexics on word recognition. Using methods developed by Castles and Coltheart (1993), we identified two subgroups who fit the profiles commonly termed "surface" and "phonological" dyslexia. Surface subjects were relatively poorer in reading exception words compared to nonwords; phonological dyslexics showed the opposite pattern. However, most dyslexics were impaired on reading both exception words and nonwords compared to same-aged normal readers. Whereas the surface dyslexics' performance was very similar to that of younger normal readers, the phonological dyslexics' was not. The two dyslexic groups also exhibited a double dissociation on two validation tasks: surface subjects were impaired on a task involving orthographic knowledge but not one involving phonology; phonological dyslexics showed the opposite pattern. The data support the conclusion that there are at least two subtypes of developmental dyslexia. Although these patterns have been taken as evidence for the dual-route model, we provide an alternative account of them within the Seidenberg and McClelland (1989) connectionist model. The connectionist model accounts for why dyslexics tend to be impaired on both exception words and nonwords; it also suggests that the subtypes may arise from multiple underlying deficits. We conclude that performance on exception words and nonwords is not sufficient to identify the basis of dyslexic behavior; rather, information about children's performance on other tasks, their remediation experiences, and the computational mechanisms that give rise to impairments must be taken into account as well.

Pseudohomophone effects and models of word recognition

Two experiments examined factors that influence the processing of pseudohomophones (nonwords such as brone or joap, which sound like words) and nonpseudohomophones (such as brone and joap, which do not sound like words). In Experiment 1, pseudohomophones yielded faster naming latencies and slower lexical-decision latencies than did nonpseudohomophones, replicating results of R. S. McCann and D. Besner (1987) and R. S. McCann, D. Besner, and E. Davelaar (1988). The magnitude of the effect was related to subjects' speed in lexical decision but not naming. In Experiment 2, both immediate and delayed naming conditions were used. There was again a significant pseudohomophone effect that did not change in magnitude across conditions. These results indicate that pseudohomophone effects in the lexical-decision and naming tasks have different bases. In lexical decision, they reflect the pseudohomophone's activation of phonological and semantic information associated with words. In naming, they reflect differences in ease of articulating familiar versus unfamiliar pronunciations. Implications of these results concerning models of word recognition are discussed, focusing on how pseudohomophone effects can arise within models that do not incorporate word-specific representations, such as the M. S. Seidenberg and J. L. McClelland (1989) model.

Characterization of the allergen group VI in timothy grass pollen (Phl p 6). I. Immunological and biochemical studies

For the identification and characterization of allergen grass group VI we performed two-dimensional immunoblotting of timothy grass pollen (Phleum pratense). Two intense 13-kD protein spots of pI 5.2 and 5.5 were found to be IgE reactive. By N-terminal microsequencing and amino acid analysis we identified them as Phl p 6 isoallergens. An antiserum was raised against Phl p 6 by immunizing BALB/c mice with allergen bearing nitrocellulose particles of one isoform. The antiserum revealed an intense reactivity to Phl p 6 isoforms, but also showed a weak cross-reactivity with Phl p 5 allergens. After immunoabsorption of patients' serum to Phl p 6 spots on the blotting membrane, we were able to demonstrate that the eluted human IgE antibodies cross-react with the grass group V allergens as well. Therefore, Phl p 5 and Phl p 6 possess one or more common IgE binding epitopes.

Characterization of the allergen group VI in timothy grass pollen (Phl p 6). II. cDNA cloning of Phl p 6 and structural comparison to grass group V

The complete primary structure of the major allergen Phl p 6 was determined by cDNA cloning. A cDNA library of timothy grass pollen was screened by a Phl p 6 directed mouse antiserum. Six clones were obtained. From the cDNA data we deduced a protein sequence of 110 amino acids. While the size of the leader sequences varied considerably between the different clones, only one amino acid exchange affected the mature proteins. Sequence comparison of group VI and V allergens showed a high degree of homology in the N- and C-terminal regions. The structural data strongly indicate that group VI and V are independent groups of allergens, which have derived from a common precursor gene.

Synthesis of 4"-deoxy motilides: identification of a potent and orally active prokinetic drug candidate

As an approach to discovering highly potent motilides with oral activity, novel 4"-deoxy derivatives of 8,9-anhydroerythromycin 6,9-hemiacetal were designed, synthesized, and evaluated for their gastrointestinal prokinetic activities. These compounds were orders of magnitude more potent than their 4"-hydroxy analogs in inducing smooth muscle contractions in an in vitro rabbit duodenal assay. Removal of the 12-hydroxy group, which was aimed at improving oral bioavailability, also afforded further potentiation in in vitro activity, leading to the identification of 8,9-anhydro-4"-deoxy-3'-N-desmethyl-3'-N-ethylerythromycin B 6,9-hemiacetal (ABT-229) as a potential prokinetic drug. ABT-229 was > 300,000 times more potent than erythromycin in vitro and had 39% oral bioavailability in dog compared to its 4",12-dihydroxy congener (EM-523), which was only 400 times more potent than erythromycin and had relatively low (1.4%) oral bioavailability.

Isolation and characterization of the 18-kDa major apple allergen and comparison with the major birch pollen allergen (Bet v I)

The major allergen from birch pollen, Bet v I, and the cross-reacting 18-kDa major allergen from Golden Delicious and Granny Smith applies were isolated by micropreparative SDS-PAGE followed by electroelution. In the case of apples, highly active, low-temperature extracts were used. The purity of the allergens was checked by analytic SDS-PAGE and immunoblotting with allergic patients' sera, as well as by N-terminal amino acid microsequencing, and the allergens were found to be very pure. The strong immunologic activity of the isolates was determined by the enzyme allergosorbent test (EAST) and EAST inhibition assays; this activity was, in the case of Bet v I, similar to that of a preparation obtained by monoclonal antibody affinity chromatography. The allergenic potency of Bet v I and of the cross-reactive apple allergen was determined by EAST inhibition and dose-related histamine release. With both assay systems, the allergenic reactivity of Bet v I was considerably higher than that of the major apple allergen. Furthermore, skin prick tests with the purified allergens and with whole allergenic extracts were performed on a group of 33 patients suffering from birch-pollen and apple hypersensitivity, and on a control group of 10 patients. The frequency of positive prick test results in the allergic patient group ranged from 73% for the major allergen from Golden Delicious apples to 97% with Bet v I and whole birch pollen extract, respectively. In contrast to our low-temperature extracts, commercial prick test solutions of four different manufacturers were found to be unreliable for the diagnosis of apple allergy. The skin test results again indicated the strong immunologic activity of the allergen isolates and the predominance of the major allergens in context with birch-pollen and apple hypersensitivity. Taken together, the results support the view that the 18-kDa major allergen represents most of the allergenicity of the the apple fruit, and that all allergenic epitopes of the apple proteins are present on Bet v I.

Structural investigations of the major allergen Phl p I on the complementary DNA and protein level

Until now investigations of group I grass allergens have mainly been performed on ryegrass allergen (Lol p I). We studied this major allergen grass group with timothy grass pollen (Phl p I), a very common and important cause of type I allergy, to determine intraspecific and interspecific variations among different grass species. By immunoscreening a timothy grass pollen complementary DNA library we obtained three full-length clones. They revealed identical nucleotide sequences in the coding regions consisting of 262 amino acids, including a leader sequence of 23 amino acid residues. The comparison of our data with the amino acid sequences deduced from Lol p I and Hol 1 I clones showed sequence identities of greater than 85% and homologies of greater than 90%, indicating a high degree of sequence conservation. Despite the high degree of homology, amino acid differences were in immunodominant positions, which may be responsible for the differing immune response to group I allergens of different grass species.

Interaction of eukaryotic initiation factor eIF-4B with a picornavirus internal translation initiation site

We studied the interaction of cellular proteins with the internal ribosome entry site (IRES) of foot-and-mouth disease virus by UV cross-linking and observed specific binding of a 80-kDa protein contained in cytosolic HeLa cell extract and in rabbit reticulocyte lysate. Binding of the protein was dependent on the presence of ATP. Immunoprecipitation with eIF-4B antiserum revealed that the protein is identical to the initiation factor eIF-4B. Deletions in the 3' part, but not in the 5' part, of the IRES interfered with UV cross-linking, indicating that the binding site of eIF-4B is located close to the end of the element. Attempts to separate ribosome-associated from non-ribosome-associated protein fractions of cytosolic cell extracts led to the loss of cross-linking activity. This finding suggests that additional protein factors contribute to this interaction of eIF-4B with the IRES of foot-and-mouth disease virus.

Molecular characterization of timothy grass pollen group V allergens

Phl p V is the dominant allergen of timothy grass (Phleum pratense) with two isoforms having the apparent molecular weights of 38 (Phl p Va) and 32 kD (Phl p Vb) under Western blot conditions. Two-dimensional electrophoresis/immunoblotting reveals that each isoform is split into at least four isoallergens. Structural differences in the isoforms are shown by N-terminal sequencing (only 60% identity), by reaction patterns of monoclonal antibodies and, more convincingly, by enzymic degradation of purified isoforms followed by immunologic fingerprinting. These findings are confirmed by the deduced primary protein structure of cloned Phl p Va and Phl p Vb. Experiments with IgE--affinity-purified by immobilized recombinant allergens or their fragments--reveal identical epitopes and at least one different epitope between the isoforms. Furthermore, on Phl p Va we can localize different IgE-reactive epitopes at the C terminus as well as the N terminus. By probing serum from 11 patients on recombinant C- or N-terminal fragments, an individual reaction pattern was found. Testing the histamine liberation potency of the fragments, we found the N-terminal fragment of Phl p Va to be superior to that of the C-terminal fragment or the whole molecule. These results give insights into the variability of allergens, the individuality of human reaction patterns to epitopes and the alteration of allergenicity to higher or lower levels by fragmentation.

Studies on the carbohydrate moieties of the timothy grass pollen allergen Phl p I

Timothy grass pollen was investigated in order to determine the carbohydrate moieties of its major grass group I (Phl p I) and to study its impact on allergenicity. Based on computer calculations one N-glycosylation site was deduced from the cDNA data of Phl p I. After two-dimensional polyacrylamide gel electrophoresis, followed by blotting of pollen extract and by use of the monoclonal antibody IG 12 we identified at least six isoallergens of Phl p I with the main spots at a molecular mass of 35-37 kDa and a pI range of 6.5-7.3. Deglycosylation by trifluoromethanesulfonic acid resulted in a decrease of about 2 kDa. Treatment with N-glycosidase A resulted in a partial deglycosylation, while N-glycosidase F and O-glycosidase had no effect. Ten lectins were investigated for their binding to Phl p I components: Aleuria aurantia agglutinin showed strong reactivity (indicating fucose residues), while Galanthus nivalis agglutinin (indicating mannose residues) and concanavalin A (indicating mannose, glucose or N-acetylglucosamine residues) showed weak binding. By neutral sugar analysis we determined similar contents of the monosaccharides in the isoallergens. In order to study the influence of the carbohydrate structures of Phl p I on IgE reactivity we tested some patient sera for their reactivity with intact and deglycosylated Phl p I. Even though most of the IgE antibodies bind at the protein core, we detected one serum that recognized carbohydrate moieties on the Phl p I.

Porcine reproductive and respiratory syndrome: temperature and pH stability of Lelystad virus and its survival in tissue specimens from viraemic pigs

We investigated the growth of Lelystad virus (LV) in porcine alveolar macrophages, the thermal and pH stability of the virus in cell culture medium, and its survival in tissue specimens from viraemic pigs. Lelystad virus grew to titres of 10(6) TCID50/ml, which were found at 40 h after virus inoculation when the macrophage cultures showed a cytopathic effect of approximately 40%. In culture medium at pH 7.5, LV was stable for prolonged periods of storage at -70 degrees C and -20 degrees C. At higher temperatures the half-life of LV was 140 h at 4 degrees C, 20 h at 21 degrees C, 3 h at 37 degrees C and 6 min at 56 degrees C. The half-life of LV, both at 4 degrees C and 37 degrees C, changed considerably when the pH of the medium was varied. At 4 degrees C and pH 6.25 a maximum half-life of 50 h and at 37 degrees C and at pH 6.0 a maximum half-life of 6.5 h was observed. However, increasing or decreasing the pH of the medium rapidly decreased the half-life of LV at both temperatures. Although, LV proved to be more stable at pH 6.00 than at pH 7.5, it did not replicate at pH 6.0. We also tested various tissue specimens from viraemic pigs for the presence of LV. The virus was detected in tonsils, lymph nodes, lungs, serum, and sporadically, albeit at low titres, in muscle tissue. The titre of virus in muscle tissue and organs was only minimally affected by storage for up to 48 h at 4 degrees C.

Elucidation of the mechanism of CryIIIA overproduction in a mutagenized strain of Bacillus thuringiensis var. tenebrionis

NB176 is a Bacillus thuringiensis mutant derived by gamma-irradiation of NB125 Bacillus thuringiensis var. tenebrionis (Krieg). It exhibits two interesting phenotypes: (i) oligosporogeny and (ii) twofold to threefold overproduction of the CryIIIA protein. Southern profiles of the NB176 strain showed an additional copy(s) of the cryIIIA gene located on a 4 kb HindIII fragment, in addition to the expected cryIIIA gene on a 3 kb HindIII fragment. Each cryIIIA gene-bearing HindIII fragment was cloned from NB176. The restriction map of the 3 kb HindIII fragment was identical to that published by Donovan and coworkers. Sequencing of the 4 kb HindIII fragment showed no alterations in the promoter region of the cryIIIA gene but did show replacement of the region immediately following the cryIIIA open reading frame with a sequence encoding a transposase with 50% amino acid homology to that of Tn1000. These findings suggest that the overproduction phenotype of NB176 results from extra copies of the cryIIIA gene produced from a transposition event(s) induced or stabilized by gamma-irradiation. Integration of additional copies of the cryIIIA gene into the native 90 MDa plasmid of the wild-type B. thuringiensis var. tenebrionis strain resulted in strains that made enormous crystals, many possessing greatly enhanced insecticidal activity.

Characterization of the 18-kDa apple allergen by two-dimensional immunoblotting and microsequencing

A low-temperature extract taken from Golden Delicious apples was separated by two-dimensional polyacrylamide gel electrophoresis. By means of two-dimensional immunoblotting with patients' serum containing IgE specific to Bet v I, a rabbit polyclonal antiserum raised against Bet v I, and two Bet v I specific monoclonal antibodies, epitopes cross-reactive to Bet v I were identified on an apple allergen with a molecular mass of 18 kDa and pI 5.5. Furthermore, certain antibody reactivities with 4 isoproteins of a molecular mass of 16 kDa and pIs ranging from 4.9 to 5.5 were observed, which may indicate the presence of Bet v I related epitopes on these proteins. Based on 26 amino acid residues, N-terminal sequencing of the 18-kDa apple allergen revealed 62% sequence identity between Bet v I from birch pollen and the apple allergen. Our results therefore support the view that both proteins express common as well as non-related IgE-reactive epitopes.

Major allergen Phl p Va (timothy grass) bears at least two different IgE-reactive epitopes

It is established that most grass pollen allergens consist of several isoforms of which the function is mainly still unknown. A number of these allergens belonging to group V have been cloned, sequenced, and expressed. Antigenic sites and IgE-reactive epitopes of the major allergen Phl p Va, are unknown. We have identified the complete cDNA sequence of a Phl p Va isoallergen by immunoscreening of a timothy grass pollen cDNA library and mixed oligonucleotide primed amplification of N-terminal cDNA. Additionally, we found an incomplete isoallergenic cDNA clone of the same protein. Immunoreactivity of the fusion proteins with patients' sera and monoclonal antibodies showed that the clones represent group Va allergens. Comparison of deduced amino acid sequences with published sequences of Lol p V and Poa p IX revealed a homology of 81.1% and 86.9%, respectively. With affinity-purified IgE antibodies recognizing the recombinant fusion protein, we can demonstrate the existence of a common group V IgE-reactive epitope. By construction of both an N-terminal and a C-terminal peptide of the complete Phl p Va and cross-inhibition, we identified at least two different IgE epitopes. Eleven patients showed variable IgE immunoreactivities to both IgE-reactive epitopes.

Trace elements in shellfish on the Danish market

Different kinds of shellfish have been investigated for their contents of the trace elements cadmium, lead, mercury, nickel, chromium, arsenic and selenium. The investigation included shrimps, mussels, lobster, langoustine, crayfish, crab claws and oyster. None of the Danish action levels for cadmium, lead and mercury respectively were exceeded, but the highest concentration of lead was very close to the Danish action levels. Shellfish do not contribute significantly to the intake of the trace elements investigated.

Epitope analysis of isoforms of the major allergen Phl p V by fingerprinting and microsequencing

The major allergen of timothy grass pollen (Phleum pratense), designated as Phl p V, consists of isoallergenic components of 38 and 32 kDa with pl values of 5.2-7.5 and 4.8-5.9, respectively. The different-sized proteins reveal similarities in IgE reactivity, N-terminal sequence and protein staining. For epitope analysis of these allergens a combination of enzymatic cleavage of electrophoretically separated proteins and immunoblotting techniques with subsequent N-terminal sequencing was performed. After isolation of the components from two-dimensional PAGE gels, proteins were enzymatically cleaved and separated by SDS-PAGE. By endoproteinase Glu-C cleavage six IgE-reactive fragments of each 32 kDa protein and three of each 38 kDa allergen were obtained. Microsequencing of the fragments revealed internal sequences that did not show any similarities between the different-sized allergens. Therefore, we assume only slight structural variations among allergens of similar sizes, whereas the 32 and 38 kDa proteins reveal great differences.

Characterization of grass group I allergens in timothy grass pollen

Using Phl p V-depleted timothy grass pollen extract (Phleum pratense) as immunogen, we obtained a monoclonal antibody, QG 4, which recognized proteins of 33, 35, and 37 kd as determined by Western blotting. The antibody cross-reacted with pollen proteins of other grass species in the molecular weight range of 30 to 37 kd. By means of two-dimensional polyacrylamide gel electrophoresis blot of timothy grass pollen extract, we demonstrated at least seven protein spots: two of 37 kd with isoelectric points of 6.4 and 6.6; four of 35 kd with isoelectric points of 6.5, 6.8, 7.1, and 7.3; and one of 33 kd with an isoelectric point of 8.5. These protein spots were also detected by patients' pooled serum. Microsequencing of the 20 N-terminal amino acid residues revealed structures with sequence identities up to 90% to the well-established allergen, Lol p I of ryegrass (Lolium perenne). Therefore we assume that the monoclonal antibody QG 4 recognized the corresponding allergen Phl p I in timothy grass pollen.

Comparison of four grass pollen species concerning their allergens of grass group V by 2D immunoblotting and microsequencing

The identification and characterization of allergenic components is a vital step towards improving diagnosis and therapy. Members of the grass family (Poaceae) reveal a high cross-reactivity among each other caused by the close phylogenetical relationship. In order to investigate the variability between allergenic components, we studied the allergen grass group V, one of the major allergens. Pollen extracts of 4 different tribes (timothy grass (Phleum pratense)--Agrostidae, perennial rye grass (Lolium perenne)--Festuceae, meadow velvet (Holcus lanatus)--Aveneae, and rye (Secale cereale)--Triticeae) of the Festucoideae subfamily were separated by 2D PAGE and investigated by immunoblotting using patients' poolserum and monoclonal antibodies (raised against group V allergens of timothy grass pollen). The antibodies identify different allergens in the four grass species. The components vary from 30-50 kDa and pI 4.8-7.0. The eight NH2-terminal amino acids were determined and indicated high similarities between the different components. These results cast doubt on the suitability of classifying allergens into groups based only on their molecular mass, isoelectric point and N-terminal sequence analysis. It suggests to classify allergens according to their IgE-reactive epitopes.

Influence of labor and neonatal hypoxia on sympathoadrenal activation and methionine enkephalin release in calves

Labor and delivery stimulate increased release of catecholamines and endogenous opioid peptides in neonates. Catecholamines promote adaptation to the extrauterine environment after birth. Enkephalins are stored together with catecholamines in the adrenal medulla and have an inhibitory effect on catecholamine release. We investigated the influence of labor and neonatal hypoxia on epinephrine, norepinephrine, and met-enkephalin release in calves. Blood samples were taken from the umbilical artery before rupture of the umbilical cord and from the jugular vein repeatedly after birth. Highest plasma norepinephrine concentration was found in calves delivered at the end of gestation (term calves) before umbilical cord rupture. In calves delivered before the physiologic end of gestation (preterm calves), norepinephrine values increased after cord rupture, but remained lower than values in term calves. Epinephrine release followed a similar pattern, but norepinephrine was clearly predominant. In term calves, met-enkephalin values were significantly higher than values in preterm calves. In calves of both groups, met-enkephalin release increased after cord rupture. During birth, the increase in catecholamine release seems to take place earlier than that of enkephalins. Norepinephrine-dominated stimulation during expulsion of the calf might be followed by increasing enkephalinergic inhibition after cord rupture and onset of respiration. Reduced release of catecholamines and enkephalins in preterm calves may be connected with delayed adaptation to the extrauterine environment.

Successful technique for the selective production of monoclonal antibodies against a major allergenic component in timothy pollen extract

Monoclonal antibodies (MAbs) were selectively raised against a major allergenic component of 38 kD in timothy grass pollen (Phleum pratense). We used a special prefractionating technique to isolate the 38 kD allergen, because immunizations with crude pollen extract had resulted in a wide variety of antibodies against other determinants, and cross-reactions between different-sized proteins occurred. Pollen extract was separated by Western blotting. Strips of the nitrocellulose membrane containing the allergen were excised, dispersed into allergen bearing particles, and used for immunization of BALB/c mice. Five MAbs were obtained that reacted with the 38 kD allergen. Four of these antibodies (BF 1, DC 9, EB 4, GE 2) exclusively detected the 38 kD protein, while one MAb (EB 6) additionally bound to a 32 kD allergen. Epitope mapping with the 3 IgG 1 antibodies (BF 1, EB 6, DC 9) was performed by ELISA inhibition tests using the purified 38 kD component. The antibodies did not interfere with each other. This confirms that they bind to different sites of the 38 kD molecule. Only a weak inhibitory effect of the MAbs on the binding of patient's IgE was determined, we suppose that the MAbs do not bind to IgE reactive epitopes. For standardization and further characterization of the 38 kD protein by peptide mapping the MAbs will be useful tools.

Accumulated O2 deficit during intense exercise and muscle characteristics of elite athletes

The accumulated O2 deficit (the difference between the estimated energy demand and the actual O2 uptake) was determined during intense exhaustive exercise (2-7 min) in elite athletes, and its relationship with muscle buffer capacity, muscle enzymes and muscle morphology was examined. Five oarsmen, fifteen soccer players, and fourteen distance runners ran, and three sprint cyclists cycled intensely to exhaustion (2-7 min). The oarsmen also performed exhaustive rowing. Blood lactate was measured immediately after several submaximal exercise bouts. A muscle biopsy was taken at rest from m. gastrocnemius of the soccer players and runners, and from m. vastus lateralis of the cyclists. The accumulated O2 deficit for the oarsmen, soccer players and runners during treadmill running was 47.3 (range: 29.6-62.4), 49.5 (34.3-73.7) and 51.9 (26.5-85.5) ml O2 equivalents ("O2-Eq").kg-1 b.w., respectively, and it was 56.5 (47.5-73.2) ml "O2-Eq".kg-1 for the cyclists during cycling. The O2 deficit was not related to blood lactate during submaximal exercise, muscle enzyme activity (citrate synthase, 3-hydroxyacyl-CoA-dehydrogenase, lactate dehydrogenase), number of muscle capillaries, %ST fibres or muscle buffer capacity. The accumulated O2 deficit was 36% higher (p < 0.05) during rowing compared to running. The present data suggest that the anaerobic energy production during intense exercise is related to the muscle mass involved. However, it appears that the anaerobic energy turnover is not determined by muscle fibre type distribution, muscle buffer capacity or muscle endurance capacity.

[Characterization of allergens of timothy grass (Phleum pratense)]

By means of 2-D electrophoresis and subsequent immunoblotting allergens of timothy grass pollen are separated as single components. Via N-terminal sequencing, it is possible to classify these components as isoallergens of defined groups according to the allergen nomenclature. We are able to identify the allergens as Phl p I, Phl p IV, Phl p V and Phl p VI.