Biomedical subjects

C Grandfils

Publications and source records attributed to C Grandfils.

23 records · Page 2Linked to original sources

PubMed1984

High-yield synthesis of a [3H]ethylenediamine ditetrodotoxin derivative.

[3H]Tetrodotoxin [( 3H]TTX) and a [3H]ethylenediamine derivative of TTX are the most widely used ligands for the study of the Na channel. The former ligand presents a low specific radioactivity (1 Ci/mmol) while the latter is highly labeled (30 Ci/mmol). However, its two-step synthesis, i.e., mild oxidation followed by coupling of [3H]ethylenediamine, has been described with a low overall yield of 1.7%. In this work, more favorable experimental conditions are defined for the limiting reaction, i.e., the oxidation step, using [14C]testosterone as a model molecule. Applied to the oxidation of tetrodotoxin, this procedure produces yield values of 30-50%, as determined by high-performance liquid chromatography. Moreover, two oxidized TTX molecules appear to be covalently linked to [3H]ethylenediamine, yielding a new labeled tetrodotoxin derivative with a specific radioactivity of 45 Ci/mmol and a dissociation constant of 0.6 nM for electroplax membranes.

Animals↗

PubMed1984

Diamine oxidase and disaccharidase activities in small intestinal biopsies of children.

A relationship between disaccharidase and diamine oxidase (DAO) activities was looked for by measuring these enzyme activities in histologically normal small intestinal biopsies of 18 children. The range for disaccharidase activities expressed in U g-1 wet weight was 0.1-5.7, 7.1-36.7, and 2.3-8.5 for lactase, maltase, and sucrase, respectively. The range for DAO activities expressed in nmol h-1 g-1 wet weight was 202-974. Significant correlations were found between disaccharidase and DAO activities (lactase versus DAO: n = 17, r = 0.80, P less than 0.001; maltase versus DAO: n = 18, r = 0.70, P less than 0.001; sucrase versus DAO: n = 18, r = 0.55, P less than 0.05). Our results further support the hypothesis that DAO is a marker of small intestinal functional integrity in children.

Amine Oxidase (Copper-Containing)↗

PubMed1984

Binding of [3H]ethylenediamine di-tetrodotoxin to its solubilized receptor from excitable tissues. Binding measurements by rapid gel-filtration and receptor stabilization by phosphatidylcholine.

The molecular study of bioelectrogenesis requires the purification of the membrane proteins involved in the Na-channel electrical activity. This complex biological structure contains various binding sites for different classes of neurotoxins. Labelled forms of the blocking agent, tetrodotoxin, are used to identified and quantified the solubilized membrane proteins during the purification. Such a specific probe was synthetized in our laboratory and this work reports the experimental set-up of the binding technique. A fast-gel-filtration method has been optimized with respect to column design, centrifugation time and speed and, delay between sample application and column centrifugation.

Animals↗

PubMedDate not supplied

Diamine oxidase in serum and small intestinal biopsy tissue in childhood celiac disease.

Diamine oxidase (DAO) activities were measured in small intestinal biopsies and in serum from control children and children with florid celiac disease. Mucosal DAO activities were found to be significantly higher in control children when compared with children with celiac disease (mean +/- SEM: 486 +/- 39 versus 121 +/- 22.1 nmol h-1 g-1 wet weight, p less than 0.001). Similarly, serum DAO activities were significantly higher in control children when compared with children with celiac disease (mean +/- SEM: 39 +/- 12 versus 13.6 +/- 2 pmol h-1 ml-1 serum, p less than 0.002). The lower serum activities associated with low mucosal values support the hypothesis that serum DAO activity reflects small bowel integrity.

Amine Oxidase (Copper-Containing)↗

PubMedDate not supplied

[The size of nanoparticles after incorporation into gastroresistant spheroids].

Nanoparticles can be used as an attractive carrier for the controlled delivery of drugs by the oral route. This nanoparticular delivery system can protect an active ingredient from enzymatic degradations and enhance its absorption from the intestinal mucosa. We studied the development of a gastroresistant dosage form for the oral administration of nanoparticles. Fast disintegrating pellets were used for the administration of nanoparticles and for their transit to the site of absorption. A gastroresistant film was applied onto the pellets to protect the nanoparticles and/ or the active substance from the acid gastric environment. The integrity of the nanoparticle size was assessed after two critical manufacturing steps: the extrusion/spheronisation process and the coating process. The determination of the nanoparticles size distribution was performed by photon correlation spectroscopy (PCS). The comparison of the PCS results between the original nanoparticles and the nanoparticles incorporated in the pellets shows a very low aggregation. Moreover the coating process was not a critical step since it was not responsible for an additional agglomeration of the nanoparticles. In conclusion, our manufacturing process allows the redispersion of the nanoparticles with a little change of the size distribution. In a next study we well try to quantify the release of the nanoparticles from the pellets.

Microspheres↗