Biomedical subjects

R Wahl

Publications and source records attributed to R Wahl.

At least 37 records · Page 2Linked to original sources

PubMed1996

Comparison of three immunoassays for diagnosing sensitization to latex in children with spina bifida.

As natural rubber latex (latex) has become more widespread in our environment, physicians have become increasingly aware of the problem of possible allergic reactions. Many fatal and near-fatal incidents have been reported (mainly during surgery) (1-3) and data has been published on groups frequently exposed to latex, such as patients with spina bifida (4-9), healthcare professionals (10-12) and occupationally exposed persons (13). The incidence of latex allergy in children seems to be increasing (14). Tests are therefore needed which can reliably detect sensitization to latex. Our aim was to compare the diagnostic accuracy of three commercial immunoassays for measuring specific IgE in serum to latex.

Adolescent↗

PubMed1996

Characterization of major allergens of Parietaria officinalis.

The major allergens of Parietaria officinalis were characterized with a panel of nine monoclonal antibodies (mAbs). The binding of mAbs and patients' IgE in Western blots revealed two proteins with similar molecular weights in the range of 8-10 kD. Analysis of the mAb-binding patterns in Western blots of P. officinalis extract under reducing and nonreducing conditions allows the mAbs to be divided into three different groups. mAbs of group I recognize the higher-molecular-weight component (9.4 kD), mAbs of group II recognize the lower component (8.8 kD) and mAbs of group III recognize both proteins. A comparable mAb-binding pattern was observed with Western blots of Parietaria judaica. The mAbs were used for affinity purification of the corresponding proteins from a P. officinalis extract. The purified proteins obtained with mAbs of group I-III inhibit the binding of patients' IgE (serum pool) to a high degree, indicating that they posses the major IgE-reactive epitopes. The affinity-purified proteins were subjected to SDS-PAGE, blotted and immunologically stained by mAb binding. The results confirmed those obtained with the complete extracts. The N-terminal amino acid sequences of the blotted proteins were analyzed. The sequences of all the proteins contained highly conserved regions: GGVV (positions 4-7) and MPPLL (positions 11-15), alternating with highly variable regions (positions 1-3 for group II and 8-10 for group I). A specific group I sequence appears to be at position 1-3 with the amino acids APA and a specific group II sequence appears to be at position 8-10 with the amino acids GAL. It is possible that the two similar proteins are isoforms of Par o 1.

Allergens↗

PubMed1995

Analysis of thyroid stimulating hormone-receptor mutations by temperature-gradient gel electrophoresis.

Somatic mutations in the genes for G-protein-coupled receptors which regulate intracellular levels of cyclic AMP have been found in several regions coding for the receptors of melanocyte-stimulating hormone, adrenaline, luteinizing hormone, rhodopsin and thyrotropin. The mutations found in the thyroid-stimulating hormone (TSH) receptor are restricted to cells of hyperfunctioning thyroid adenomas and other thyroid tumors. They are thought to lead to a constitutive activation of the receptor independent of TSH. We have developed a temperature-gradient gel electrophoresis (TGGE) assay starting with the amplification of a part of exon 10 of the TSH-receptor gene to screen tissue of thyroid tumours. TGGE allows the detection of point mutations even if there are only a few cells with somatic mutations in tissue sections.

Adenoma↗

PubMed1995

Examination of recombinant truncated mature human fibroblast collagenase by mass spectrometry: identification of differences with the published sequence and determination of stable isotope incorporation.

Human fibroblast collagenase belongs to a family of matrix metalloproteinases which have been implicated in a number of connective tissue disorders ranging from rheumatoid arthritis to tumor invasion. To examine the active site of this enzyme by biophysical studies, a 19 kDa recombinant truncated mature collagenase (mCL-t) was prepared. Electrospray ionization (ESI) and matrix-assisted laser desorption/ionization (MALDI) mass spectrometry have been utilized for the characterization of mCL-t. The molecular weights measured by these techniques identified the presence of two closely related protein components separated by approximately 100 Da. Edman sequence analysis demonstrated that the two protein components differ from each other by an amino terminal valine, consistent with the mass spectrometric data. In addition, the molecular weight of mCL-t determined by mass spectrometry did not agree with that calculated from the reported sequence. To identify the origin of this discrepancy, the DNA sequence of the mCL-t clone was examined. Several differences were noted between the DNA sequence of mCL-t and the published collagenase gene sequence. When these differences were taken into account, the measured molecular weights were found to be in good agreement with that calculated for the modified sequence. In separate experiments, both ESI and MALDI mass spectrometry have been used to determine molecular weights of mCL-t samples enriched with stable isotopes 15N and (15N + 13C). The measured molecular weights demonstrated a 97% (15N) and 99% (15N + 13C) incorporation of labeled isotopes in the two samples.

Amino Acid Sequence↗

PubMed1995

[Iodine content in diet and excretion of iodine in urine].

The standard food for our volunteers, prepared in the central kitchen of the University Hospital of Tubingen, consisted of breakfast, warm lunch and cold supper and contained, on average, approximately 230 micrograms of iodine/day. It is generally assumed that an equilibrium is established between iodine intake from food and urinary iodine excretion. Hence, the amount of iodine excreted with the urine within 24 h may reflect the daily ingestion of iodine. The fecal iodine losses are considered negligible. The alimentary iodine supply from food of our clinic would meet the WHO recommendations of > 150 micrograms/day to prevent iodine-deficiency goiters. In 27 healthy volunteers the daily uptake of iodine was determined and the urinary excretion of iodine within 24 h was measured. Unexpectedly, only 16% to 18% of the alimentary iodine were excreted with the urine. Hence, the utilization of iodine from the food appears to be limited and therefore cannot prevent goiters in goiter areas. In addition, it was found that the correlation between urinary excretion of iodine and urinary excretion of creatinine is not a reliable parameter for the real daily excretion of iodine and iodine balance.

Biological Availability↗

PubMed1995

Synthesis and biological evaluation of radioiodinated phospholipid ether analogs.

Previous work has shown that radioiodinated phospholipid ether analogs with the iodine-125 substituted on the meta position of the aromatic ring readily localized in a variety of animal tumors. In an effort to ascertain the importance of such meta substitution, three phospholipid ether analogs with the iodine-125 in the para position were synthesized for evaluation as potential tumor-localizing imaging agents. 12-(p-Iodophenyl)dodecyl phosphocholine, 1-O-[12-(p-iodophenyl)dodecyl]-1,3-propanediol-3-phosphocholine, and 1-O-[12-(p-iodophenyl)dodecyl]-2-O-methyl-3-rac-glycerophosphocholine were synthesized and labeled with iodine-125 via an isotope exchange procedure. Similar to previous results with the meta substituted analogs, tissue distribution studies with the three para analogs demonstrated tumor localization and retention of radioactivity at 24 h after i.v. injection. In all three cases, the para isomers showed greater tumor avidity than the meta isomers and clearance of the radiotracer from the tumor was much slower than the clearance from nontarget tissue. 12-(p-Iodophenyl)dodecyl phosphocholine afforded the greatest tumor-to-nontarget tissue ratio. For example, the tumor-to-blood and tumor-to-liver ratios at 24 h were 10.96 and 1.85, respectively. As a result of such selective tumor retention, it was possible to clearly delineate the tumor using gamma-camera scintigraphy.

Animals↗

PubMed1995

ECDC--a totally integrated and interactively usable genetic map of Escherichia coli K12.

A printed version of the interactively usable genetic map of Escherichia coli K12 is provided together with some statistical information about the actual status of the respective genome sequencing project. A total of 3,179,967 bp corresponding to 68.38% of the genome is available through the ECDC database. Contigs as well as individual DNA sequences for each gene or open reading frame are provided. Access to a number of other databases is possible using World Wide Web or local programs.

Chromosome Mapping↗

PubMed1995

Efficiency of various dissociation methods for the preparation of thyroid single cell suspensions.

For comparison of the physiological potential of single thyroid cells versus cells integrated into follicles it would be ideal to work with suspensions consisting exclusively of single cells instead of a mixture of single cells and follicle fragments. In this study, various techniques for the isolation of single cells have been tested for their effect on cell viability, the ultrastructure of the isolated cells, the percentage of single cells and the ability of these cells to form follicles in culture. In addition, the cells were characterized for the preservation of their morphology and the ability to respond to TSH by comparing their immunocytochemical staining pattern with anti-vimentin and anti-ras p21 antibody to that of the intact thyroid tissue. Dispase treatment of thyroid tissues alone produced suspensions with a relatively small proportion of single cells. These cells stained with anti-vimentin and anti-ras p21 antibody to a similar percentage as thyroid cells in the intact gland. A combination of dispase treatment with either filtration or trypsin treatment severely compromised the viability of the cells. A high proportion of single cells with a good viability could be obtained either by centrifugation of dispase treated tissues or by culturing of dispase treated tissues as monolayers and subsequent detachment from the culture vessels with trypsin. Whereas the immunological staining with anti-vimentin and anti-ras oncogene antibody in the centrifuged cells resembled that of intact tissue, cells cultured as monolayers reacted differently. The differences in the immunological staining were still observed when the cells which had been grown as monolayers were stimulated with TSH. Differential centrifugation appeared to be the ideal method for the isolation of unaltered and viable single cells but is a rather laborious method to obtain larger amounts of single thyroid cells.

Animals↗

PubMed1995

The allergen of Ficus benjamina in house dust.

Ficus benjamina, a member of the Moraceae family, is a tropical, non-flowering green plant which is widely used for ornamental purposes. It is an occupational allergen in plant keepers but sensitization is also increasingly found in non-occupationally exposed atopic and non-atopic patients. The allergen of Ficus benjamina is located in the plant sap, a so-called latex. By radioallergosorbent test-(RAST)-inhibition studies allergen could also be demonstrated in the dust collected from the leaf surface and in dust samples from the floor of rooms where the plant was placed. These findings could result in more extensive preventive measures in patients sensitized to Ficus benjamina. In addition there is some evidence that possibly a crossreactivity between latex of Ficus benjamina and latex from the rubber tree Hevea brasiliensis, a member of the Euphorbiaceae family, may exist.

Adolescent↗

PubMed1995

Inhibitory and disruptive effects of some antirheumatics on antigen-antibody complexes.

Purified antibodies to human serum albumin or to human gamma-globulin were used to study the direct influence of some antirheumatic drugs on the formation and disruption of immunoprecipitates. 125I-labelled human serum albumin and 125I-labelled human IgG served as indicators. The effects of the following drugs were described: diclofenac, monophenylbutazone, diphenylbutazone, ibuprofen, and metamizol. At approximately therapeutic concentrations, the antirheumatics inhibited the formation of complexes of homologous antibodies with human serum albumin and, surprisingly, with human IgG. When the antigens were precipitated with antibodies, subsequent addition of the antirheumatics to the preformed immunoprecipitates caused disruption of [125I]human serum albumin-anti-human serum albumin precipitates but practically no disruption of human [125I]IgG-anti-human IgG precipitates. These new findings may be of relevance for clinical diagnosis and therapy as well as for research in immunochemistry. It is conceivable that, in patients, antirheumatic or other drugs might interfere with immunological determinations of clinico-chemical quantities. Interference of drugs with antigen-antibody reactions might also help to explain some beneficial effects or undesirable side effects of certain drugs.

Analgesics↗

PubMed1995

Basal lamina formation by porcine thyroid cells grown in collagen- and laminin-deficient medium.

Porcine thyroid cells isolated by dispase treatment were cultured in either (a) Matrigel, (b) agarose with the addition of different combinations of basic fibroblast growth factor and laminin, or (c) on agarose-coated dishes. The formation of follicles and the presence of a basal lamina was investigated by routine electron microscopy of Araldite-embedded material and by light and electron microscopical immunocytochemical detection of the basal lamina components, laminin and collagen type IV. After 10 days of culture in Matrigel or agarose, a basal lamina-like structure surrounded most follicles. Follicles of cells growing in agarose and overlaid with a medium containing thyrotropin and overlaid with a medium containing thyrotropin and fibroblast growth factor showed a fluorescent band at the basal side of the follicles after immunocytochemical staining with anti-laminin and anti-collagen antibodies. Routine electron microscopy showed that a basal lamina-like structure lined the outside of the follicle. This structure could be subdivided into a lamina lucida and a lamina densa. Electron microscopical immunogold labelling revealed that immunologically detectable laminin was confined to the lamina densa. These findings suggest that even in the absence of basal lamina components in the culture medium, thyroid cells are able to form follicles with a regular basal lamina when they are cultured in a three-dimensional environment.

Animals↗

PubMed1994

ECD--a totally integrated database of Escherichia coli K12.

We have compiled the DNA sequence data for E. coli available from the GENBANK and EMBL data libraries and independently from the literature. Starting with this update of our Escherichia coli database (ECD release 20) we provide major changes compared to previous issues. This update not only represents another substantial increase in sequence information, it also allows now to find the exact physical location of each individual gene or regulatory region, even regarding discrepancies in nomenclature. In order to save space this printed version does not contain the database itself anymore, but we provide several examples. The complete database is publically available in electronic form together with a self explaining application program or as a flat file. The complete compilation including a full set of genetic map data and the E. coli protein index can be obtained in machine readable form from the EMBL data library as a part of the CD-ROM issue of the EMBL sequence database, released and updated every three months. After deletion of all detected overlaps a total of 2,878,364 individual bp is found to be determined till the end of June 1994. This corresponds to a total of 60.98% of the entire E. coli chromosome consisting of about 4,720 kbp. This number may actually be higher by 9161 bp derived from other strains of E. coli.

Base Sequence↗

PubMed1994

Seasonal occupational asthma in an agricultural products merchant--a case report.

A 52-year-old agricultural products merchant reported mild occupational asthma and rhinitis throughout the year, with severe asthma from February to May. He had been exposed to various substances, particularly grain, insecticides, fungicides, and fertilizers over 35 years. We identified a castor-bean-containing fertilizer as the cause of the disease by skin prick test and bronchial provocation test. Specific IgE against castor bean was detected by enzyme allergosorbent test, and proteins with mol. mass of less than 14.4 kDa and masses of 15.5, 29.5, and 30.5 kDa were identified as allergens by Western blot analysis. The seasonal character of symptoms could be explained by a more frequent use of the fertilizer during spring. Six months after avoidance of the allergen, the patient reported chronic bronchitis without asthma. Occupational allergy to castor bean should be considered in subjects with seasonal asthma and exposure to "natural" fertilizers.

Asthma↗

PubMed1994

Quality control in mammography: an initiative in France.

The ultimate effectiveness of any mass screening campaign is directly related to strict compliance with certain rules and technical protocols designed for radiological installations. Concerning radiological screening, the primary technical objective is to ensure reproducibly high quality images at low radiation dose to the patient. This paper describes the methodology followed for the implementation of a quality control (QC) programme of 48 mammography installations used within the context of the breast cancer screening campaign in the Bas-Rhin region of eastern France. In order to demonstrate the efficacy of such a programme, results of QC tests and procedures relating to each element of the radiological imaging chain are presented and compared for four control visits carried out at 6 month intervals over a period of 2 years. A reduction of 50% (from 16 mGy to 7.5 mGy) of breast entrance doses (normalized to a breast thickness of 4.5 cm) and a significant improvement of detectability of high contrast details are discussed. The importance of encouraging an extension of a similar process to the other screening experiments currently underway in France is emphasized.

Aged↗

PubMed1994

Oxalic acid in saliva, teeth and tooth tartar.

Oxalic acid was determined in human saliva, teeth, tartar, and in animal teeth. Saliva from dentally healthy male subjects contained 0.10 +/- 0.09 mmol/l (n = 41) and those of dentally healthy female subjects 0.18 +/- 0.17 mmol/l (n = 40). Oxalic acid in tartar from 16 patients was 3.3 +/- 1.2 mmol/kg tartar. In human teeth, oxalic acid was 1.0 +/- 0.3 mmol/kg in milk teeth (n = 12) and 0.9 +/- 0.6 mmol/kg in permanent teeth (n = 60). Human teeth were sorted into age groups and into molars, incisors and premolars. In animal teeth, oxalic acid content varied widely. The formed calcium oxalate is proposed to be a 'physiological' protective mechanism for teeth.

Adolescent↗

PubMed1993

Compilation of DNA sequences of Escherichia coli (update 1993).

We have compiled the DNA sequence data for E. coli available from the GENBANK and EMBL data libraries and over a period of several years independently from the literature. This is the fifth listing replacing and increasing the former listings substantially. However, in order to save space this printed version contains DNA sequence information only, if they are publically available in electronic form. The complete compilation including a full set of genetic map data and the E. coli protein index can be obtained in machine readable form from the EMBL data library (ECD release 15) as a part of the CD-ROM issue of the EMBL sequence database, released and updated every three months. After deletion of all detected overlaps a total of 2,353,635 individual bp is found to be determined till the end of April 1993. This corresponds to a total of 49.87% of the entire E. coli chromosome consisting of about 4,720 kbp. This number may actually be higher by 9161 bp derived from other strains of E. coli.

Base Sequence↗

PubMed1993

Monoclonal antibody immunoassay for quantitative analysis of group V allergens in grass pollen extracts.

A two-site monoclonal antibody (MoAb) ELISA has been developed for the quantification of the Phleum pratense major allergen, Phl p V. The assay is based on two MoAbs which recognize different non-overlapping epitopes on the Phl p V molecule; one antibody (1D11) was immobilized on the solid phase and the other (3B2) was biotinylated. An affinity-purified Phl p V preparation (purity of 95%) was used as standard. The assay has a sensitivity of 10 ng/ml of allergen and is suitable for the detection of group V allergen in aqueous grass extracts. The specificity of the assay was investigated with 14 grass pollen and five non-grass pollen extracts. Different levels of group V allergen were detected in extracts of grasses, but not in non-grasses. The assay gives a good correspondence with allergenic activity of extracts as determined by ELISA inhibition using serum pool of allergic patients. The results indicate that the two-site MoAb ELISA could be very useful in the standardization of allergenic extracts from grass pollen.

Allergens↗

PubMed1993

Oxalate in the human thyroid gland.

Ninety-seven fixed surgical thyroid specimens and 63 unfixed and 40 fixed thyroid specimens from autopsies were examined for their oxalate content. Proteases were used to process the tissue, and the oxalate was determined with an enzymatic assay. The fixed samples were grouped into seven diagnostic categories (diffuse colloid goitre; partially diffuse, partially nodular colloid goitre; nodular colloid goitre; goitre with multifocal functional autonomy; non-functioning adenoma; unifocal functional autonomy; Graves' disease). The oxalate concentrations of the samples were mainly dependent on age and gender, which were distributed unequally among the seven diagnostic groups. In thyroid tissue from cases of Graves' disease, however, the concentration of oxalate was remarkably low and statistically different from those of four of the six other groups.

Adenoma↗