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Biomedical subjects

P Delorme

Publications and source records attributed to P Delorme.

At least 37 records · Page 2Linked to original sources
PubMed1989

Bovine brain endothelial cells express tight junctions and monoamine oxidase activity in long-term culture.

The passage of substances across the blood-brain barrier is regulated by cerebral capillaries which possess certain distinctly different morphological and enzymatic properties compared to capillaries of other organs. Investigations of the functional characteristics of brain capillaries have been facilitated by the use of cultured brain endothelial cells, but in most studies a number of characteristics of the in vivo system are lost. To provide an in vitro system for studies of brain capillary functions, we developed a method of isolating and producing a large number of bovine brain capillary endothelial cells. These cells, absolutely free of pericyte contamination, are subcultured, at the split ratio of 1:20 (20-fold increase of the cultured surface), with no apparent changes in cell morphology up to the fiftieth generation (10 passages). Retention of endothelial-specific characteristics (factor VIII-related antigen, angiotensin-converting enzyme, and nonthrombogenic surface) is shown for brain capillary-derived endothelial cells up to passage 10, even after frozen storage at passage 3. Furthermore, we showed that bovine brain capillary endothelial cells retain, up to the fiftieth generation, some of the characteristics of the blood-brain barrier: occurrence of tight junctions, paucity of pinocytotic vesicles, and monoamine oxidase activity.

Animals↗
PubMed1988

Catecholamine and indoleamine levels in chick cultured neurons and embryonic brain.

Catecholamine and indoleamine levels were determined in cultured neurons from chick embryos and in the "homologous" embryonic cerebral hemispheres in order to study their neurotransmission systems. The seeding of a large number of cells resulted in a pure neuronal culture made of clusters interconnected by processes. Norepinephrine, which was absent from the starting material of the culture, appeared on the 2nd day and then decreased. A small amount of epinephrine was present on the 2nd day and decreased thereafter. Dopamine was not detected. In the cerebral hemispheres of chick embryos, dopamine appeared on the 10th day in ovo and increased steadily up to the 18th day. Epinephrine was also present in the cerebral hemispheres. Its level increased up to the 14th day and then decreased. Indoleamines were measured in the same material. The level of serotonin was markedly higher than that of catecholamines and it increased during cultivation. Tryptophan was already present in the starting material and its amount increased during cultivation. The level of 5-hydroxyindoleacetic acid changed like that of serotonin. In the embryonic cerebral hemispheres, the concentration of serotonin was highest on the 12th day after incubation and then decreased. Tryptophan level decreased steadily all during the embryogenesis. These results were discussed on the ground of differences in the synthesized neurotransmitters.

Animals↗
PubMed1986

Glycogen synthesis and immunocytochemical study of fructose-1,6-biphosphatase in methionine sulfoximine epileptogenic rodent brain.

The effects of the convulsant methionine sulfoximine (MSO) on the glucose pathway have been investigated in mouse and rat brain. The key gluconeogenic enzyme fructose-1,6-biphosphatase (FBPase) (EC 3.1.3.11) was immunostained by rat anti-FBPase antibody. The rat cortex slices were very lightly stained, almost unstained in controls. After MSO injection, there was a marked staining only in astrocytes (perikarya, processes, and end feet). The activity of this enzyme also increased. MSO induced an increase of 63% in the stability at heating (47 degrees C) and of 36% in the stability at proteolysis (trypsin, 10 micrograms/ml) of FBPase. The convulsant had no effect on the concentrations of the metabolites related to the FBPase-phosphofructokinase step, i.e., fructose-1,6-biphosphate, glyceraldehyde-3-phosphate, and dihydroxyacetone phosphate, before, during, or after the convulsions. These results show that the cellular site of glucose pathway impairment induced by MSO in rodent brain is presumably the astroglial cells and that one mechanism of glycogenesis could be the reinforcement of the molecules of FBPase, which enhances gluconeogenesis. A hypothetical diagram of glucose metabolism under the effect of MSO has been proposed.

Animals↗
PubMed1983

[Ultrastructural study of acute ischemia at the cerebral level. Effects of 5023 SE].

The effects of ischaemia on nervous tissue and cerebral capillary vessel ultrastructure and their prevention by Duxil were studied in rabbits. Ischaemia induced by bilateral occlusion of the carotid arteries induced minor changes in the endothelium of some capillary vessels: irregularities in the luminal surface with subsequent increase in the number of caveolae, increase in the number and size of membrane microvillosities and bullae, and retraction of the nuclei. Ischaemia acted mainly on astrocyte processes and perikarion which became shollen with altered mitochondria and complete absence of glycogen. The neurons remained normal but seemed to contain slightly more lysosomes. After administration of Duxil 10 min before ischaemia was induced, there were no endothelial changes; the astrocytes were less swollen and above all, their glycogen content was preserved; there seemed to be less lysosomes in the neurons. The effects of Duxil on cell oxygenation and oxidative metabolism may account for its protective action on endothelial, glial and neural cells.

Acute Disease↗
PubMed1983

[Ultrastructural study of acute ischemia at the peripheral level. Effects of 5023 SE].

The effects of ischaemia on the arterial wall were studied in fragments of common carotid artery taken downstream from the occlusion. They consisted of intracytoplasmic or intrajunctional lacunae, vacuoles, craters, detachment or disruption of cell membranes with formation of blebs or bullae, retraction of numerous nuclei, swelling of the ergastoplasm and perhaps increase in pinocytosis. The administration of Duxil, a corrector of metabolism, 10 min prior to inducing ischaemia resulted in considerable reduction of these lesions as compared to untreated animals.

Acute Disease↗
PubMed1979

Ultrastructural and biochemical studies of the swelling of developing chick telencephalic slices.

An ultrastructural and biochemical study of the importance and localization of tissue swelling was performed on telencephalic slices of 1- and 30-day-old chicks incubated in an oxygenated or a non-oxygenated physiological medium. The swelling of slices is greater for 30-day-old chick material than for that from 1-day-old chicks. It also reaches higher values in the non-oxygenated than in the oxygenated medium. When the 30-day-old chick telencephalic slices are incubated in an oxygenated medium, swelling mainly affects astrocytes, and especially the astrocytic endfeet. When they are incubated in a non-oxygenated medium, the astrocytes and astrocytic endfeet are very swollen and in addition the swelling also affects the neurons and their organelles. Extracellular space is increased. When 1-day-old chick telencephalic slices are incubated in a non-oxygenated medium, the tissue structures are well preserved. Swelling predominantly affects astrocytes and astrocytic endfeet. Neurons are not affected and the extracellular space is reduced. However, when they are incubated in an oxygenated medium, tissue structures are greatly affected showing a high degree of disorganization. Extracellular space is greatly increased. This study thus indicates that the best incubation conditions are an oxygenated medium for 30-day-old chick telencephalic slices which are characterized by an aerobic metabolism, and a non-oxygenated medium for 1-day-old chick telencephalic slices which have a predominantly anaerobic metabolism.

Aerobiosis↗
PubMed1978

An autoradiographic study on the biosynthesis of the capillary basal lamina in the chick embryo telencephalon.

The elaboration of the basal lamina of telencephalic capillaries has been studied by autoradiography in chick embryos from day 16 to 19 of incubation. The cerebral vascular basal lamina is actively synthesized during the period of these stages of development. The animals were sacrificed 2, 15, 40 and 180 min after intravenous injection of 3H-proline. The hydroxylation of proline to hydroxyproline in the "secretory" cells permits their identification. Our observations suggest that endothelial cells, pericytes and perhaps glial cells participate in this elaboration. The various stages of the synthesis are performed sequentially in the ergastoplasm and then in the Golgi apparatus before the secretory material is released by exocytosis.

Animals↗
PubMed1978

[Effects of hypertonic solutions on the excitation-contraction coupling of the skeletal muscle fibre of the crab. II. Ultrastructural aspects (author's transl)].

Experiments were performed to investigate the modifications of electrical activity and the loss of contraction by examination of the ultrastructure. These alterations were obtained with a control physiological solution (artificial sea water, ASW) which was made hypertonic by adding sucrose, glycerol, choline chloride or urea. 1. Under these conditions, the ultrastructural results show that: a) all those substances induce a modification of the coupling junction (either diad or triad). This modification can explain the inhibition of the mechanical phenomenon; b) sucrose (Figs. 6C and 6D) and glycerol (Figs. 4A and 4B) induce alterations of the surface membrane and of the tubular system (less important with glycerol). They can explain the decrease of the resting potential and the abolishment or the modification of the action potential; c) in contrast, choline chloride (Figs. 7A to 7E) and urea (Figs. 9A to 9F) only modify the organisation of the coupling junction. The action potential is maintained. 2. A short exposure of the fibre in an isotonic sucrose solution (Figs. 5A to 5D) deeply modifies the tubular system, particularly, in cutting it off from the sarcolemma. 3. Choline chloride and urea produce similar changes in the ultrastructure but as urea is not ionized, it can be added to the ASW to investigate the electrical phenomenon which cannot be modified by contraction.

Animals↗
PubMed1977

Subcellular distribution of cytochrome c oxidase, monoamine oxidase and lactate dehydrogenase in the developing chick telencephalon.

The distribution of cytochrome c oxidase monoamine oxidase and lactate dehydrogenase, together with protein, after isopycnic centrifugation of a crude mitochondrial fraction of chick telencephalon homogenate in a linear sucrose density gradient, was followed during late embryogenesis and postnatal maturation. Two main populations of subcellular organelles differentiate; they were characterized biochemically and analyzed by electron microscopy. One population, with a progressively defined mean buoyant density of 1.170 g/ml, exhibited a high relative activity of monoamine oxidase, with a low and relatively constant cytochrome c oxidase/monoamine oxidase activity ratio. This population was composed of free mitochondria and mitochondria enclosed in nerve endings, and possibly of mitochondria of perikaryal and glial origin. A second population, with a progressively well defined mean buoyant density of 1.182-1.186 g/ml, exhibited a high relative activity of cytochrome c oxidase, with a high and increasing cytochrome c oxidase/monoamine oxidase activity ratio. The biochemical and functional significance of these results were discussed.

Animals↗
PubMed1975

Diffusion of horseradish peroxidase perfused through the lateral ventricle of the chick telencephalon.

Horseradish peroxidase, perfused into the lateral ventricle of chick brain, freely and slowly diffuses through the cerebral extracellular spaces. The layer of astrocytic end-feet surrounding blood capillaries does not consitute a barrier to the tracer which permeates the basal lamina, diffuses between the pericytic cells and finally accumulates in the intercellular space beneath the tight junctions between contiguous endothelial cells. No evidence was found for transport by micropinocytotic vesicles from the cerebral parenchyma to the capillary lumen.

Animals↗