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Biomedical subjects

P Pradelles

Publications and source records attributed to P Pradelles.

At least 109 records · Page 6Linked to original sources
PubMed1979

Enkephalin-like products in embryonic chicken retina.

Using sensitive and highly specific radioimmunoassays, Met-enkephalin (Met-ENK) and Leu-enkephalin (Leu-ENK) have been shown to exist together in the retina of chicken embryo. After high performance liquid chromatography (HPLC), a fraction of the retinal extracts seems to be authentic Met-ENK. Following a G-50 filtration, the Met-ENK immunoreactivity has been found associated to three peaks, the lightest having an apparent molecular weight similar to that of the Met-ENK.

Animals↗
PubMed1978

Analytical methods for thromboxane B2 measurement and validation of radioimmunoassay by gas liquid chromatography-mass spectrometry.

A sensitive and specific radioimmunoassay using a 125I tracer of high specific radioactivity was developed for thromboxane B2 and was applied to the determination of the in vitro biosynthesis of this compound in some systems (i.e. human washed platelets, human platelet rich plasma (PRP) and rat spleen homogenates). The assays were also evaluated by mass spectrometry; levels measured by these two analytical methods were very similar. The results obtained for washed human platelets with a thin layer radiochromatographic method were in good agreement with the two preceeding methods.

Animals↗
PubMed1977

[5-hydroxytryptamine-sensitive adenylate cyclase activity in brain synaptosomal membrane preparations].

A serotonine-sensitive adenylate cyclase system has been observed in horse brain membrane preparations. In crude mitochondrial fraction two types of activation sites were characterized, the Ka being = 2 nM and 1 micrometer. In purified synaptosomal membranes, a single adenylate cyclase activation was observed corresponding to the highest apparent affinity (KD = 2nM). This activation site might be related to the high affinity binding site (KD = 2NM) were previously described in the same membrane preparations.

Adenylyl Cyclases↗
PubMed1977

The use of iodinated tracers for a sensitive radioimmunoassay of 13,14-dihydro-15-ketoprostaglandin Falpha.

Radioimmunoassay of 13,14-dihydro-15-ketoprostaglandin Falpha is reported using various 125I-labelled derivatives. The apparent association constants of the antiserum for iodinated tracers are higher than with the homologous hapten. In spite of this, the high specific activities of iodinated tracers (2000 Ci/mmol) allow a 3-fold increase in the sensitivity of the assay when compared with the tritiated derivative. Human plasma levels of 13,14-dihydro-15-ketoprostaglandin Falpha reported (25+/-6 pg/ml) are lower than those previously found by radioimmunoassay, and no sexual difference was found.

Binding Sites↗
PubMed1976

125I derivatives of prostaglandins. A novel approach in prostaglandin analysis by radioimmunoassay.

We report the production of radioactive iodinated (125 I) derivatives of prostaglandins E1, E2, F2alpha and their use in radioimmunological assays. Histamine or tyramine was coupled to the prostaglandins carboxyl group and the iodination was accomplished using the chloramine T method. The high specific radioactivity of these tracers and the resolution of the purification procedure allowed the detection of 0.5 pg of prostaglandins. A comparison with tritiated prostaglandin was made and showed a 10-fold gain in sensitivity. Furthermore in the case of the prostaglandin E1 system using 125I-labelled histamine or tyramine as tracer the cross reaction curves obtained were different from those obtained with [3H]prostaglandin E1; we suggest that the blocking of the carboxyl group alters the prostaglandin E1 structure, modifying its immunoreactivity.

Amniotic Fluid↗
PubMed1976

Fate of thyrotropin releasing hormone after binding and stimulation of prolactin release by GH3 cells. Evidence for release of unmodified (3H)-TRH.

GH3 cells which had been exposed for 30 min to (3H)-TRH and had performed their maximun biological response, i.e. increase of prolactin (PRL) release, retained intracellular radioactivity which consisted of chemically unmodified TRH (greater than or equal to 93%). Such preloaded GH3 cells were found able to spontaneously release into the culture medium a radioactive material (3H)-RM) which was analyzed. The kinetics of binding of (3H)-RM to intact GH3 cells and competition with unlabeled TRH were indistinguishable from (3H-TRH. (3H)-RM was able to stimulate PRL release from GH3 cells. In addition thin layer electrophoresis (TLE) revelaed that 90% of (3H)-RM migrated like TRH reference. All these features strongly suggest that (3H)-RM is identical to (3H)-TRH.

Cell Line↗