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Biomedical subjects

G Campistron

Publications and source records attributed to G Campistron.

At least 37 records · Page 2Linked to original sources
PubMed1988

Immunocytochemical localisation of GABA in endocrine cells of the rat entero-pancreatic system.

The occurrence of GABA-containing cells in the rat entero-pancreatic system was investigated by using anti-GABA-glutaraldehyde antibodies at the light and electron microscope level. In the pancreas, the B cells showed intense immunoreactivity, contrary to non-B and exocrine cells. Moreover, post-embedding immunogold staining was localised mostly in mitochondria, close to rough endoplasmic reticulum and in the nucleus. The insulin granules appeared nonsignificantly stained, which suggests the lack of cosecretion of GABA together with insulin. In the duodenum, GABA immunoreactivity was detected in certain endocrine cell types, suggesting a possible interaction with this amino acid. The well established GABAergic innervation in the enteric system was also confirmed by immunolabelling.

Animals↗
PubMed1987

Immunocytochemical localization and morphology of GABA-containing neurons in the prefrontal and frontoparietal cortex of the rat.

The distribution and morphology of gamma-aminobutyric acid (GABA)-containing neurons in the rat prefrontal, frontal and parietal cortex were examined using a specific polyclonal antiserum directed against GABA and the immunoperoxidase method. The reaction product was present in the cell bodies, as well as in terminals and some processes without using colchicine. The immunoreactive neurons were observed in all layers but their laminar distribution was different in each cortical area. The immunoreactive cells were more numerous: in layer II and layer V-VI of the frontal cortex, in the deep layers (IV, V, VI) of the parietal cortex and in layer II and layer VI of the prefrontal cortex. The neurons displaying a labelling both in perikarya and processes were classified as multipolar and bipolar neurons. We distinguished various subtypes in each category. Multipolar neurons: cells with a large round soma and thin dendrites radiating in all directions; small neurons with ovoid or angular soma; large neurons with multiangular soma; neurons with a piriform soma. Bipolar neurons: horizontal bipolar cells with ovoid soma and vertical bipolar neurons with fusiform soma.

Animals↗
PubMed1987

Pharmacokinetics of bendazac-lysine and 5-hydroxybendazac in patients with renal insufficiency.

The pharmacokinetics of bendazac and its major metabolite, 5-hydroxybendazac, have been investigated in 15 patients with moderate to severe renal insufficiency and renal failure following a single oral dose of 500 mg bendazac-lysine. The pharmacokinetic parameters were compared to those obtained in 10 healthy adult volunteers. The rate and the extent of absorption of bendazac was not modified in the patients with moderate and severe renal insufficiency, nor was there any change in plasma tmax, Cmax, apparent elimination t1/2 and AUC. There was a significant increase in the unbound fraction of bendazac in renal failure patients undergoing haemodialysis, with a consequent increase in the apparent volume of distribution (V/F) and apparent plasma clearance (CL/F), and a decrease in plasma Cmax and AUC. Simultaneous changes of V/F and CL/F lead to an unchanged plasma t1/2 in these patients. Renal clearance (CLR) was decreased, but CL/F was not affected, since renal excretion is a minor route of elimination of bendazac. Bendazac is mostly eliminated by metabolism to 5-hydroxybendazac, in healthy subjects greater than 60% of a dose being excreted in urine as 5-hydroxybendazac and its glucuronide. In patients with renal insufficiency urinary excretion of 5-hydroxybendazac was decreased and the systemic availability of the metabolite (AUC), was increased about three-fold, irrespective of the degree of renal failure. Plasma 5-hydroxybendazac glucuronide accumulated according to the degree of renal insufficiency. Overall it can be assumed that the pharmacological effect of the drug will not be enhanced in renal failure and that the dosage regimen of bendazac-lysine in such patients need not be modified.

Adult↗
PubMed1987

A double-peak phenomenon in the pharmacokinetics of veralipride after oral administration: a double-site model for drug absorption.

Equal doses of veralipride have been given to 12 healthy volunteers by three different administrations--intravenous infusion, oral solution, and oral capsules--in a randomized cross-over design. After the intake of the solution, but not after infusion or capsules, two maximum plasma concentrations have been observed and interpreted, according to a double-site model for drug absorption.

Administration, Oral↗
PubMed1987

Effect of size and dosage strength on the bioavailability of two diltiazem formulations during repeated administrations in humans.

In angina pectoris, diltiazem is usually prescribed as two 60 mg tablets in the morning and two 60 mg tablets in the evening. In the course of the pharmaceutical development of this drug, it was therefore planned to study an experimental formulation containing 120 mg of diltiazem. On the basis of dissolution tests in vitro, a bioavailability study was initiated to compare the 120 mg experimental formulation to the standard 60 mg tablet. The study was conducted in 12 healthy volunteers who received the 2 treatments (one 120 mg tablet bid for 7 days versus two 60 mg standard tablets bid for 7 days) according to a cross-over design. Blood and urine samples were analysed by HPLC method with a UV spectrophotometric detection (sensitivity: 5 ng/ml). Analysis of variance did not show any significant difference between the two formulations for the following parameters: maximum plasma levels observed at steady-state, area under the curves and unchanged urinary diltiazem. From these results the extent of absorption of the 120 mg experimental formulation can be considered as bioequivalent to the administration of 2 tablets of the 60 mg commercially available diltiazem formulation. The time to peak, however, was delayed in 75% of the subjects with the 120 mg diltiazem tablet, showing that the surface area of the pharmaceutical preparation is of primary importance for drug dissolution and rate of absorption.

Angina Pectoris↗
PubMed1987

An ultrastructural study of GABA-immunoreactive neurons and terminals in the septum of the rat.

The fine structure and types of contact made by GABAergic elements in the septal nuclei were studied at the electronmicroscopic level by means of peroxidase immunocytochemistry, using anti-GABA antibodies. Observations were made on normal and colchicine-injected rats. GABA-immunoreactivity was distributed within somata, dendrites, axonal varicosities and terminals, and myelinated axons. The peroxidase reaction product was diffuse in the cytoplasm; cytoplasmic organelles were generally devoid of immunoreactivity, while showing a strong reaction on the outer surface of their membrane. GABA-immunoreactive (GABA-I) neurons were small (10 microns on average) to medium (20 microns) in size, with round or multipolar cell bodies. Additionally, labeled large (30 microns) cells were observed within the myelinated fibers of the medial septal nucleus after intraseptal administration of colchicine. No difference in the ultrastructural features and distribution of the immunoreactivity of the 2 kinds of cell was noticed, except for a higher number of synaptic contacts on large neurons of the medial septum. GABA-I cells of the medial and lateral nuclei received synapses on their soma and dendrites, made by both immunonegative and GABA-I terminals. Nonimmunoreactive boutons contacting GABA-I cell bodies were of 2 types: those containing small, clear synaptic vesicles and those that additionally contained large dense vesicles. Synaptic vesicles of GABA-I boutons were rarely labeled internally, but showed varying electron densities. Synapses made by GABA-I boutons on GABA-I or unlabeled somata and dendrites were always of symmetrical type. Synapses made by non-GABA-I boutons on GABA-I cells were either symmetrical or asymmetrical.

Animals↗
PubMed1987

Immunocytochemical approach of GABAergic innervation of the mouse spinal cord using antibodies to GABA.

The distribution of gamma-amino-butyric acid containing neurons in the Mouse spinal cord has been studied at both the light and electron microscope levels using antibodies against GABA and revelation by the Fab-peroxidase technique. At the light microscope level immunoreactive profiles of perikarya and neuronal processes were particularly abundant in the superficial laminae (I-IV) of the dorsal horn. Scattered soma profiles were found in the other layers and more particularly in the lamina X where Liquor contacting immuno-reactive neurons could be detected. GABAergic cell bodies were very sparse in the ventral horn. Electron microscopic observations confirmed the light microscope results: terminals constituted synaptic symmetrical contacts that provide a morphological basis for inhibition in the dorsal horn and for post-synaptic inhibition of motoneurons in the ventral horn.

Animals↗
PubMed1986

Glycine neurons in the brain and spinal cord. Antibody production and immunocytochemical localization.

Antibodies were raised against glycine and they were specific for immunocytochemistry. Obtained from rabbits immunized with glycine conjugated to glutaryled protein-carriers, antisera were then purified by adsorption on the various glutaraldehyde-conjugated protein-carriers. Using a modified ELISA method, their specificity was determined in competition experiments between conjugated glycine and either non-conjugated glycine or other conjugated amino acids or derivatives, preincubated with anti-glycine antibodies. Calculated at half-displacement, the resulting cross-reactivity ratios showed conjugated glycine to be the best recognized compound. By revealing the presence of the majority of the glycine-containing cell bodies in the brainstem and spinal cord, immunocytochemical applications of glycine antibodies confirmed their use as specific tools for a better understanding of the role of glycine in the central nervous system.

Animals↗
PubMed1986

Specific antibodies against aspartate and their immunocytochemical application in the rat brain.

An immunological approach to visualize aspartate in the rat brain was attempted by raising antibodies against this acidic amino acid. Using an adapted ELISA method, their specificity was tested by competition experiments between aspartate conjugated via glutaraldehyde to various protein-carriers and either non-conjugated aspartate or conjugated amino acids, preincubated with anti-aspartate antibodies. Their titer and specificity were found high enough to allow their use in immunocytochemistry which demonstrated the presence of a large number of aspartate-containing cell-bodies in many areas of the brain.

Animals↗
PubMed1986

Immunological approach to the detection of taurine and immunocytochemical results.

An immunological approach to the detection of taurine resulted in antibodies specific enough to be used for immunocytochemical studies. The experimental conditions were similar to those previously described for raising antibodies against some small-sized neurotransmitter molecules: antisera were obtained from rabbits immunized with taurine conjugated to carrier proteins via glutaraldehyde and purified by adsorption on the glutaraldehyde-treated protein carriers. Antibody affinity and specificity were determined in competition experiments between conjugated taurine and other conjugated amino acids or derivatives by enzyme-linked immunosorbent assay. The resulting cross-reactivity ratios, calculated at half-displacement, showed conjugated taurine to be the best recognized compound. Given the molecular structure of taurine and the method used to prepare the conjugate, it seemed necessary to perform an oxidation step. However, adsorption of antisera on reoxidized or nonreoxidized taurine conjugates suggested that reoxidation did not make a significant difference. Immunocytochemical application of the sera revealed populations of strongly immunopositive nerve cells in the cerebellum, striatum, and septum. The results confirmed that antitaurine antibodies can be used as specific tools for a better understanding of the role of taurine in the central nervous system.

Animals↗
PubMed1986

Pharmacokinetics and bioavailability of doxycycline in humans.

The bioavailability of a new tablet of 6-deoxy-5-hydroxytetracycline (doxycycline, Doxycline Plantier) was estimated relatively to an oral solution and a commercially available capsule. Each form was administered to 12 healthy volunteers according to a replicated latin square. Statistical analysis of non-compartmental pharmacokinetic parameters - maximum concentrations, corresponding time, area under the plasma concentrations curve and unchanged amounts recovered in the urine - failed to show any difference between the tested pharmaceutical forms, although the new tablet allows to reach higher concentrations.

Adult↗
PubMed1984

Effects of arginine aspartate and its components on growth hormone, insulin and glucagon secretion in the rat.

The effects of orally administered arginine aspartate (250 mg per kg) on the secretion of insulin, glucagon and growth hormone in the rat have been compared with those of equimolar doses of arginine (142 mg per kg) and aspartic acid (108 mg per kg). There were no significant changes in the blood levels of insulin and glucagon. Arginine aspartate increased growth hormone levels whereas its two components failed to induce any significant changes. This stimulatory effect on growth hormone is discussed.

Animals↗
PubMedDate not supplied

Pharmacokinetics of arginine and aspartic acid administered simultaneously in the rat--III: Changes in the levels of amino acids in the plasma, liver and brain after simultaneous administration of arginine and aspartic acid.

Changes in the levels of amino acids in the plasma, liver and brain were studied in rats after simultaneous administration of 0.1 mmol/rat of arginine and aspartic acid. The levels of most of the assayed amino acids underwent various changes some of which only occurred in one of the organs studied, for example, GABA in the brain and proline in the liver. It is difficult to advance any explanation. Meanwhile some of changes can be explained on the grounds of well-known metabolic changes. The large increase of ornithine in the liver may be due to the action of arginase in the first stage in the urea cycle. This amino acid is the precursor of glutamic acid and proline which may explain the high levels of these two amino acids observed especially in the liver. The increase of GABA in the brain may be due to the simultaneous administration of arginine and aspartic acid which could induce the formation of ornithine and alpha-ketoglutaric acid respectively, two metabolites known to increase cerebral GABA. The increases in Ser, Gly, and Ala observed in practically all the tissues studied may be due to the formation of oxaloacetate from aspartic acid.

Administration, Oral↗