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P Delree

Publications and source records attributed to P Delree.

18 recordsLinked to original sources
PubMed2006

Antigens and granularity of blood monocytes in relation to inflammatory markers and lipids in postmenopausal women.

OBJECTIVES: The menopause is associated with an increase of inflammatory markers (C-reactive protein, fibrinogen), cytokines (INFgamma, TNF, etc.) and blood lipoproteins. In vitro, CRP, LDL and fibrinogen can modulate or potentiate interleukines production by monocytes. The aim of this work was to study, the relationships in vivo between hs-CRP, fibrinogen, lipoproteins and the phenotype of circulating monocytes. METHODS: The monocytes phenotype, in postmenopausal women (n=26) without history of cardiovascular disease, was determined, by flow cytometry, measuring granularity and CD14, HLA-DR and CD62-L antigens expression. Blood monocytes were divided in CD14+dim monocytes (low CD14 expression) and CD14+bright monocytes (high CD14 expression). RESULTS: HLA-DR was negatively correlated with hs-CRP and fibrinogen. The relationships between ApoB, LDL/ApoB ratio and CD14 expression was restricted to the CD14+bright monocytes. Blood lipids, i.e. total cholesterol, LDL-c and ApoB were correlated with the granularity of both subsets. CD14+dim monocytes were characterized by a low granularity and CD62-L expression. CONCLUSIONS: Our data show that fibrinogen and hs-CRP are correlated with a reduced antigen-presenting capacity. Expression of CD14 on CD14+bright monocytes is negatively associated to atherogenic LDL. Blood monocytes granularity was positively correlated with serum lipids indicating that monocytes could uptake modified LDL in circulation and not restricted to subendothelial space.

Aged↗
PubMed2005

[Experimental comparative evaluation of the functional capacities of ectopically grown fetal organs].

The interest for fetal organ, tissue, and cell implantation as therapeutic means in the treatment of some diseases is presently increasing. Hence, the aim of the present investigation was the comparative evaluation of the functional potential of ectopically grown fetal organs of different (ecto-, meso- and endodermic) origins. Unified operative model was the fetal organ fragment implantation into an ear subcutaneous pouch (without restoration of vascular and nervous links of the implant with the recipient organism). The implant isolation in vitro varied from 15 to 50 min. As control, intact animals and animals with streptozotocin diabetes and hepatic lesions due to the main bile duct ligature, were used. The implanted and ectopically grown fetal organs, though of different origins, developed functional activity. The best adult-like function was obtained in intestinal, gastric and cardiac implants, i.e. in organs with a cavity and a well developed self-regulation system. Poorer results were obtained in great digestive glandular implants--pancreas and liver. In the best cases when the implant function was very closed to the adult organ, a difference nevertheless was observed. The model of ectopic implantation of fetal organs may be useful for study of the organ and tissue function ontogenesis (up to the moment of natural ageing involution), for the evaluation of different isolated factor influence on organ and tissue physiology and pathology. Although being optimistic in respect to clinical application of fetal organ and cell implantation, this study does not prevent us from being cautions.

Animals↗
PubMed2004

Oxidation of low density lipoproteins by myeloperoxidase at the surface of endothelial cells: an additional mechanism to subendothelium oxidation.

The present paradigm of atherogenesis proposes that low density lipoproteins (LDL) are trapped in subendothelial space of the vascular wall where they are oxidized. Myeloperoxidase (MPO) plays a key role in oxidative damage. We propose that LDL oxidation by myeloperoxidase (Mox-LDL) could occur at the surface of the endothelial cells and not restricted to the subendothelial space. The triad constituted by endothelial cells, circulating LDL and MPO in close interaction, constitutes a synergic mechanism for the genesis of Mox-LDL.

Cell Membrane↗
PubMed1997

Sciatic nerve regeneration through venous or nervous grafts in the rat.

This study analyses the interest of isologous venous grafts filled with saline or with Schwann cells versus nerve grafts as guides for regeneration of the sciatic nerve in 35 Wistar rats. Electrophysiological parameters (conduction velocities and distal latencies of motor responses) and the functional index of De Medinacelli were measured several times from 1 month to 1 year after surgery. An histological analysis was performed on 2 control rats and on 3 rats killed 6 or 12 months after surgery: the total number of fibers was counted on a montage photoprint of the whole nerve, and the diameters of axons and the thickness of the myelin sheath were measured on digitized images. With a portion of nerve as guide, the regeneration is faster than with a vein. However, regeneration after 6 months is at least as good with a venous graft filled with Schwann cells, as assessed by electrophysiological, functional, and histological analysis. The addition of Schwann cells in grafted veins allows the nerve to regenerate through longer gaps than previously described (25 vs 15 mm). In order to assess the quality of nerve regeneration, functional, electrophysiological, and histological analysis are complementary.

Animals↗
PubMed1995

Preparation of a macroporous biodegradable polylactide implant for neuronal transplantation.

This article reports the production of a surgical implant meeting several specific requirements such as biocompatibility, biodegradability, macroporosity, and flexibility. Porosity was controlled by an original method consisting of the aggregation of calibrated poly-D,L-lactide microparticles. The size of the interstices between the aggregated microspheres was in a direct relationship to the microsphere diameter. A first approach was based on coating the microspheres with poly(vinyl alcohol) followed by chemically crosslinking the coating layers that were in mutual contact. This method was disregarded because of the acute cytotoxicity of glutaraldehyde used as the crosslinking agent, the absence of macroporosity, and the complete lack of flexibility. A physical technique of aggregation was then tested, which relied on the plasticization of poly-D,L-lactide microspheres with triethylcitrate to the point where microspheres strongly adhered to each other when they were in contact. This method has proved to be straightforward and definitely superior to the chemical approach, particularly with respect to cytotoxicity, control of macroporosity, and flexibility. A polymer support was thus successfully which was biodegradable, macroporous( interconnected pores of 10-100 microns in diameter), and flexible. This potential medical device is presently being used for neuronal transplantation in the central nervous system.

Animals↗
PubMed1993

Syngeneic grafting of adult rat DRG-derived Schwann cells to the injured spinal cord.

A subdural inflatable micro-balloon was used to induce closed traumatic contusion to adult rat spinal cord. This spinal cord injury model was associated with reproducible and graded neurological deficits and histopathological alterations. At various delays after injury, transplantations of syngeneic adult cultured dorsal root ganglion-derived Schwann cells were performed into the spinal cord lesion. The transplants were well integrated and reduced the microcystic posttraumatic cavitation as well as the gliosis. Schwann cells transplants were invaded by numerous regenerating neurites most of which, based upon their neurotransmitter contents, seem to originate from the dorsal root ganglion.

Animals↗
PubMed1992

In vitro and in vivo modulation of 5-hydroxytryptamine-, thyrotropin-releasing hormone- and calcitonin-gene related peptide-like immunoreactivities in adult rat sensory neurons.

In a previous work we have shown that culturing adult rat dorsal root ganglia neurons modifies their neurotransmitter phenotype in such a way that cultured neurons synthesize transmitters that are not found in situ, while several other transmitters are expressed in a much higher percentage of neurons in culture than in situ [Schoenen J. et al. (1989) J. Neurosci. Res. 22, 473-487]. The aim of the present study was to investigate the origin and the nature of the relevant environmental signals that allow this plasticity to be expressed, focusing on three neurotransmitters: 5-hydroxytryptamine, thyrotropin-releasing hormone and calcitonin-gene related peptide. The main results can be summarized as follows: (1) culturing cells in fetal calf serum or on feeder layers of astrocytes, Schwann cells or fibroblasts partially inhibits the serotoninergic phenotype of dorsal root ganglia neurons; (2) in vivo disconnection of dorsal root ganglia from their spinal targets but not from their peripheral or supraspinal targets induces a significant increase of the percentage of 5-hydroxytryptamine- and thyrotropin-releasing hormone-positive neurons in disconnected ganglia; (3) growth factors such as ciliary neuronotrophic factor or basic fibroblast growth factor but not nerve growth factor repress 5-hydroxytryptamine and calcitonin gene-related peptide immunoreactivity in cultured sensory neurons. In conclusion, neurotransmitter gene expression of adult dorsal root ganglia neurons is controlled by complex influences. Our data suggest that thyrotropin-releasing hormone and 5-hydroxytryptamine gene expression are tonically repressed in vivo by factors originating from the spinal segmental level and that growth factors such as ciliary neurotrophic factor or basic fibroblast growth factor could be potential vectors of this repressing effect.

Animals↗
PubMed1990

Potassium-induced release of an endogenous toxic activity for outer hair cells and auditory neurons in the cochlea: a new pathophysiological mechanism in Menière's disease?

In Menière's disease, the increase of extracellular potassium concentration in the perilymph is thought to play a key role in determining the progressive loss of cochlear hair cells. In this paper, we describe a serum-free culture preparation of hair cells from 5 day-old rat and report the release by the cochlea, in response to an increase of extracellular potassium concentration, of a cytotoxic activity active on hair cells and auditory neurons. The toxic activity is associated with low molecular weight (less than 10,000 Dalton) molecule(s) as revealed by ultrafiltration. Morphological studies performed on the organ of Corti incubated during 24 h in the presence of the cochlea-derived toxic activity (CTA), show that this factor is toxic for hair cells and not for supporting or surrounding cells. The release of CTA occurs both in the spiral ganglion and in the organ of Corti. We suggest that this cochlea-derived toxic activity may play an important role in the pathophysiology of the hearing loss that occurs during the progression of Menière's disease.

Animals↗
PubMed1990

Neuronotrophic effect of developing otic vesicle on cochleo-vestibular neurons: evidence for nerve growth factor involvement.

In the developing inner ear, the existence of a neuronal death and of a peripheral target-derived trophic effect on cochleovestibular neurons has been documented. Using cultures of rat cochleovestibular neurons, we show that the E12 otic vesicle releases a factor promoting the survival and the neuritogenesis of these neurons, and that this effect is mimicked by NGF. The effect of the optic vesicle conditioned medium (OVCM) on cochleovestibular neurons is suppressed by anti-NGF antibodies. OVCM is neuronotrophic for NGF-sensitive sympathetic neurons, an effect that is also suppressed by anti-NGF antibodies, further demonstrating the presence of biologically active nerve growth factor.

Adrenergic Fibers↗
PubMed1990

Enhanced release of plasminogen activator inhibitor(s) but not of plasminogen activators by cultured rat glial cells treated with interleukin-1.

Astroglial cells are known to proliferate during development of the nervous system, as well as during post-traumatic gliosis. We have previously shown that the proliferation of cultured astrocytes can be stimulated by the urokinase-type (uPA) of plasminogen activator (PA) and that astrocytes are able to release such uPA upon stimulation with basic fibroblast growth factor, which is known to act as a mitogen for these cells. Here we report studies on the effects of human interleukin-1 (IL-1) on the release of PA activity by cultured newborn rat astroglial cells. Whereas there is controversy in the literature as to whether IL-1 stimulates multiplication of astroglial cells, we failed to observe such an effect in our system. We did observe, however, a dose-dependent decrease in PA activity in the supernatant of the IL-1 treated cultures. Further analysis revealed that this apparent decrease in PA release was in fact due to an increased release of plasminogen activator inhibitor (PAI). A similar IL-1 induced increase in PAI release was also found to occur in cultures of transformed astrocytes (human glioma LN18) and in cultured Schwann cells, but not in cultures of neurons or neuronal tumour cells. Since protease inhibitors are known to possess neuritogenic properties, our results suggest that IL-1, by its capacity to induce PAI, may promote neuritogenesis.

Adrenal Gland Neoplasms↗
PubMed1990

Cultured neurons release an inhibitor of astroglia proliferation (astrostatine).

Using in vitro techniques, we looked for a possible downregulation of rat astroglia proliferation by neuronal cells. We demonstrate that medium conditioned by 7-day-old rat cerebellar granule neurons or by 16-day-old rat embryo hippocampal neurons strongly inhibits the proliferation of cultured astroglial cells. Two neuronal cell lines, the PC12 rat pheocromocytoma and the neuro 2A (N2A) murine neuroblastoma also release such an activity. This release in N2A-conditioned medium (CM) occurs when the cells are at high density and show a low proliferation rate. This activity is present in media conditioned by neuronal cells, but not in media conditioned by normal astrocytes, by two glioma cell lines, or by one fibroblastic cell line. This proliferation inhibitor addresses normal astrocytes: the proliferation of two glioma cell lines, of a fibroblastic cell line, and of the two neuronal cell lines (PC12, N2A) is not inhibited by N2A CM. Moreover, this activity is directed against type 1 astrocytes, but not against type 2. Using three different assays, we demonstrate that DNA synthesis by astroglial cells is inhibited. N2A CM has no cytotoxic effect on astrocytes and does not modify their overall protein synthesis. Using affinity and gel filtration chromatography, we show that this activity is associated with a protein whose molecular weight ranges between 15 and 20 kDa. The possible relationship between this N2A cell-derived astroglia proliferation inhibitor and other types of potential glial proliferation inhibitors has been investigated. A brain glycoprotein immunologically related to epidermal growth factor receptor (EGFR) was reported to inhibit astroglial cell proliferation in vitro. Using polyclonal and monoclonal antibodies against EGFR, we were unable to immunoprecipitate the astrocyte proliferation inhibitor in N2A CM or to demonstrate by immunoblotting the presence of an EGFR-like immunoreactivity in the N2A CM or in the active chromatographic fractions of N2A CM. Transforming growth factor beta (TGF beta) is a well-known modulator of the proliferation of various cell types and was shown to be present in N2A CM. Using a polyclonal anti-TGF beta antibody that recognizes TGF beta on Western blots of N2A CM, we were unable to immunoprecipitate the astrocyte proliferation inhibitor of N2A CM. It seems thus far that the neuronal astroglia proliferation inhibitor is a new protein for which we propose the name astrostatine.

Animals↗
PubMed1989

Neurotransmitter phenotype plasticity in cultured dissociated adult rat dorsal root ganglia: an immunocytochemical study.

Culturing sympathetic ganglion neurons in vitro may modify phenotypic expression of some neurotransmitters. For dorsal root ganglia (DRG), contradictory results have been reported; most studies have used immature material. We have therefore performed a detailed immunocytochemical analysis of the transmitter content of cultured adult rat DRG neurons. To demonstrate possible modifications of neurotransmitter phenotypes, we have compared the results obtained with the same techniques on neurons cultured for 3 days and on freshly dissociated DRG cells. Also, the transmitter profile of cultured neurons was compared with that known from in situ studies. Out of 22 antigens studied, 20 were detected in cultured DRG neurons. All of them were expressed in small and/or intermediate-sized cells. Large neurons only contained CGRP, VIP, NPY, beta-END, ENK, and GABA. The percentage of immunostained neurons varied for the various antisera: less than 10% of cultured neurons were positive for ENK, beta-LPH, beta-END, DYN, VASO, and OXY; 10-30% for SOM, CCK, CAT, and SP; and greater than 30% for NPY, CRF, GLU, NT, VIP, GABA, GRP, CGRP, 5-HT, and TRH. In the latter two groups of transmitters (except CGRP), the proportion of immunoreactive neurons was by far larger in cultured than in freshly dissociated DRG. The most pronounced (greater than 25%) increase in the proportion of positively stained neurons after culturing was observed for the GRP, CRF, TRH, and 5-HT antisera. Serotonin was the only transmitter identified in cultured but not in freshly dissociated cells. These data indicate, on one hand, that various antigens, for example, CAT, GABA, NT, TRH, NPY, beta-LPH, and beta-END, which up to now have not been described in DRG in situ, can be detected immunocytochemically a few hours after dissociation of adult rat DRG. On the other hand, several transmitters, for example, VIP, NPY, SP, GABA, GLU, NT, GRP, CRF, TRH, and 5-HT, are expressed in a significantly higher proportion of cells in cultured than in freshly dissociated preparations. This might reflect a change in the phenotypic expression of transmitters due to the new environment generated by the culture conditions, a hypothesis that can be tested by measuring specific mRNA levels. Moreover, considering the plasticity and multipotentiality of their transmitter phenotype, cultured adult DRG neurons might represent an interesting material for autografts into the injured central nervous system.

Animals↗
PubMed1989

Purification and culture of adult rat dorsal root ganglia neurons.

To study the trophic requirements of adult rat dorsal root ganglia neurons (DRG) in vitro, we developed a purification procedure that yields highly enriched neuronal cultures. Forty to fifty ganglia are dissected from the spinal column of an adult rat. After enzymatic and mechanical dissociation of the ganglia, myelin debris are eliminated by centrifugation on a Percoll gradient. The resulting cell suspension is layered onto a nylon mesh with a pore size of 10 microns. Most of the neurons, the diameter of which ranged from 17 microns to greater than 100 microns, are retained on the upper surface of the sieve; most of the non-neuronal cells with a caliber of less than 10 microns after trypsinization go through it. Recovery of neurons is achieved by reversing the mesh onto a Petri dish containing culture medium. Neurons to non-neurons ratio is 1 to 10 in the initial cell suspension and 1 to 1 after separation. When these purified neurons are seeded at a density of 3,000 neurons/cm2 in 6 mm polyornithine-laminin (PORN-LAM) coated wells, neuronal survival (assessed by the ability to extend neurites), measured after 48 hr of culture, is very low (from 0 to 16%). Addition of nerve growth factor (NGF) does not improve neuronal survival. However, when neurons are cultured in the presence of medium conditioned (CM) by astrocytes or Schwann cells, 60-80% of the seeded, dye-excluding neurons survive. So, purified adult DRG neurons require for their short-term survival and regeneration in culture, a trophic support that is present in conditioned medium from PNS or CNS glia.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1989

[Current trends in experimental peripheral nerve regeneration].

Large posttraumatic defects in the peripheral nervous system need to discover methods to solve the demand of nerve grafts. There is no definite answer now. The authors present a model for nervous regeneration studies. Experiments are performed in the Wistar rat. A venous isograft is used to bridge defects of various size in a divided rat sciatic nerve. The venous tube is a guide for axonal regeneration. In one series, the tube is filled with physiological saline and, in a second one, neonatal Schwann cells are injected in the venous isograft. Results recorded are a combination of quantitative methods: neurophysiology and morphometry. The injection of neonatal Schwann cells is able to stimulate nerve regeneration but not completely.

Animals↗
PubMed1989

[Neuronotrophic interactions in the developing inner ear].

In the developing inner ear, the existence of a neuronal death and of a peripheral target-derived trophic effect on the embryonic cochleovestibular neurons is described. We investigate the molecular vector(s) of such neuronotrophic influences on the cochleovestibular neurons, particularly the nerve growth factor (NGF) which is a good candidate since receptors for this trophic factor are described in the embryonic inner ear. In 12 day-old rat embryos, we demonstrate the release of an NGF-like activity by the otic vesicle and the effect of this trophic factor on the survival and the neuritogenesis of the cochleovestibular neurons. We suggest an important role for NGF in the neuronal stabilisation of the cochleovestibular ganglion and the invasion of the otic vesicle by the neurites. The study of the neuronotrophic interactions in the inner ear is then applied on more mature auditory neurons. In the 5 day-old rat cochlea, we also show the release by the central and the peripheral targets of a trophic activity allowing the survival of the afferent auditory neurons. These neuronotrophic factors may play an important role in the secondary degeneration of the auditory neurons following an injury of the Corti's organ or of the central target. The effect of NGF is also investigated on these neurons and we demonstrate that NGF has a neuritogenic but not a survival promoting effect on the 5 day-old rat afferent auditory neurons.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1987

Potassium-induced release of neuronotoxic activity by astrocytes.

Medium conditioned by newborn rat cerebral cortex microexplants contains neuronotoxic activity for cerebellar granule cells and hippocampal neurons. The neuronotoxic activity is associated with low-molecular weight molecule(s) (less than 1000 Da) and resists to heating and to freezing and thawing. Using nearly homogenous cultures of neurons or astrocytes, we show that the neuronotoxic activity is released by the latter cell type. This release is enhanced by increasing extracellular K+-concentration. Astrocytes also secrete neuronotrophic activity whose release is not affected by external K+. Neurons can be desensitized against the neuronotoxic activity.

Animals↗
PubMed1987

Plasminogen activators in developing peripheral nervous system, cellular origin and mitogenic effect.

Newborn rat dorsal root ganglia release two different plasminogen activators (PAs): the urokinase (UK) and the tissue (tPA) type. The former is secreted by neurons while the latter is secreted by Schwann cells. tPA release by Schwann cells is modulated by choleratoxin, a known mitogen for these cells. UK but not tPA stimulates in a dose-dependent fashion the proliferation of Schwann cells. This effect is observed in the absence of plasminogen, suggesting that the substrate for PAs in the developing nervous system is not plasminogen. Since UK is secreted by neurons, our data suggest a new mechanism for neuronal control of Schwann cell proliferation.

Animals↗