Search PubMed⌕ Search

Biomedical subjects

M Bickel

Publications and source records attributed to M Bickel.

102 records · Page 6Linked to original sources
PubMed1978

Studies on the effect of tolbutamide, glibenclamide, HB 699, and glucose on serum insulin and blood glucose in gastro-enterectomized dogs.

The influence of intravenously administered tolbutamide, glibenclamide, HB 699, and glucose on serum insulin and blood glucose kinetics was examined in 36 enterectomized dogs. The substances induced an immediate and long-lasting insulin release even in the absence of all insulinotropic intestinal mediators. Maximum and mean insulin concentrations after treatment, measured for 180 minutes, were markedly higher in resected dogs than in sham operated or non-operated animals. The data suggest that intestinal mediators might be of no importance in vivo for the insulin-releasing activity of the compounds examined, at least in dogs.

Animals↗
PubMed1977

Chemical and biological properties of porcine secretin and secretin analogues modified in positions 3 and 4.

The synthesis of secretin does not offer fundamental difficulties any longer. The problem of the stability of the hormone seems to be solved from a practical point of view. However, the mechanism of the inactivation of secretin in solution is not yet satisfactorily explained, alpha-beta Rearrangement of the Asp-Gly bond may play a role, but some observations indicate that inactivation is not a straight reaction. Like secretion [Ala-4] secretin shows beta-sympathomimetic activity. The availability of a suitable depot preparation permits physiological studies with secretin and its analogues after subcutaneous administration.

Animals↗
PubMedDate not supplied

Analogues and fragments of secretin.

For the purpose of analytical investigation and structure/activity relationships, some secretin analogues and secretin fragments have been synthesized. HPLC comparison of the synthesized products with our synthetic secretin revealed about 2% [D-Ala17]secretin, 1% [D-Leu13]secretin and less than 1% aminoterminal degradation products. The D-Ala17 content can be eliminated if the starting material used for segment coupling (Z-Arg(Z2)-Asp(OBut)-Ser(But)-Ala-OH) has no D-Ala-contamination. In addition, traces of the rearrangement products [3-aspartoyl]-secretin and [beta-Asp3]secretin are suspected. Secretin can be degraded to several compounds by chromatography on a strong basic ion exchanger in 1% acetic acid. These products are more polar than secretin and have no biological activity. The secretin content measured by HPLC correlated well with the biological data, since the degradation products and other byproducts separated by HPLC have only a negligible influence on the pancreatic flow.

Amino Acid Sequence↗
PubMedDate not supplied

Motilin and a synthetic enkephalin induce colonic motor complexes (CMC) in the conscious dog.

In the conscious dog migrating and nonmigrating colonic motor complexes (CMC) were recorded by means of chronically implanted strain gauge force transducers. Intravenous injection of a synthetic enkephalin analogue immediately induced a premature CMC at all three recording sites of the colon. Naloxone inhibited the enkephalin- but not motilin-induced CMC. We therefore exclude that motilin acts by release of endogenous enkephalins. The two peptides stimulate CMC in the canine colon by different pathways. Naloxone alone had no effect on normal colonic motility, suggesting strongly that endogenous enkephalins do not modulate regular CMC in the dog.

Animals↗
PubMedDate not supplied

Results of the international Pu-2000 exercise for plutonium isotopic composition measurements.

An international comparison for plutonium isotopic composition measurement, known as the Pu-2000 exercise, was organized by the ESARDA NDA-WG (European Safeguards Research and Development Association, Working Group on Techniques and Standards for Non-Destructive Assay). The aim of this comparison was to test X- and gamma-ray spectrometry methods over a large range of isotopic ratios. These methods are based on the complex analysis of several X- and gamma-rays in the KX region of the plutonium spectrum and also in the 120-700 keV energy range. The results obtained by the participants with their corresponding uncertainties are presented in this document and compared to the declared values. The main conclusions of the work are also given. No important bias due to an inadequate knowledge of the nuclear data for plutonium isotopes was observed.

International Cooperation↗
PubMedDate not supplied

Characterisation of reference materials for radioactivity with assigned values traceable to the SI units.

The Institute for Reference Materials and Measurements participates in an IAEA co-ordinated project to upgrade Analytical Quality Control Services intercomparison materials to reference materials. The principal objective is to ensure that assigned property values are traceable to the International System of Units. General principles and practical mechanisms for achieving this traceability are described.

Journal Article↗
PubMedDate not supplied

Validation of methods for the determination of radium in waters and soil.

This article describes the advantages and disadvantages of several analytical methods used to prepare the alpha-particle source. As a result of this study, a new method combining commercial extraction and ion chromatography prior to a final co-precipitation step is proposed. This method has been applied and validated on several matrices (soil, waters) in the framework of international intercomparisons. The integration of this method in a global procedure to analyze actinoids and radium from a single solution (or digested soil) is also described.

Alpha Particles↗
PubMedDate not supplied

Aspects of sample preparation for the determination of actinoids in soil.

In the frame of the re-certification measurements of the IAEA-375 soil reference material the activity concentration of four actinoids (U, Th, Pu and Am) was determined. The method is based on microwave digestion or aqua regia leaching, separation by extraction chromatography and alpha-particle counting source preparation by co-precipitation or electro-deposition. This article describes some of the problems encountered during the validation of the sample preparation method and their solutions.

Actinoid Series Elements↗
PubMedDate not supplied

B lymphocyte derived hematopoietic growth factors.

The present study was undertaken to elucidate the effect of bacterial lipopolysaccharides (LPS) on B lymphocyte derived hematopoietic growth factors. Bone marrow-derived (BM) B cells and homogeneous B cell lines (lymphomas and hybridomas) were used to study the production of granulocyte-macrophage colony stimulating factor (GM-CSF). The BM B cells required two signals for GM-CSF production: LPS and a tumor promoting phorbol ester (TPA). In the B cell lines, GM-CSF production was inducible with LPS alone. Molecular analysis of the GM-CSF gene expression revealed that steady state levels (as determined by Northern analysis) of GM-CSF mRNA could be detected only in LPS-induced cells, whereas it was found by nuclear transcription analysis that the GM-CSF gene is transcribed even in uninduced cells. However, biological activity of GM-CSF was detected only in supernatants from LPS-induced cells. These data suggest a post-transcriptional regulation of this gene.

Animals↗