Search PubMed⌕ Search

Biomedical subjects

P Legrand

Publications and source records attributed to P Legrand.

95 records · Page 6Linked to original sources
PubMedDate not supplied

Relationship between NO-synthase activity and TNF-alpha secretion in mouse macrophage lines stimulated by a muramyl peptide entrapped in nanocapsules.

The present study evaluates the ability of a new drug carrier: nanocapsules of poly(D,L-lactide) containing muramyldipeptide-L-alanyl-cholesterol (MTP-Chol NC) to induce activation of mouse macrophage cell lines. MTP-Chol NC stimulated nitric oxide (NO) expression and tumor necrosis factor-alpha (TNF-alpha) production, these are two important mediators of macrophage-mediated cytotoxicity. The encapsulated form was more effective than free muramyldipeptide, at low immunomodulator concentrations. The dose-response curves were completely different for NO and TNF-alpha, implying different regulatory mechanisms. In RAW 264.7 cells, the addition of anti-TNF-alpha antibodies during the activation period did not affect the level of nitrite induced by MTP-Chol Nc and lipopolysaccharide. Therefore, autocrine stimulation by TNF-alpha did not contribute to NO production. On the other hand, the presence of an NO synthase inhibitor led to an increase in TNF-alpha secretion. In J774.A1 cells, which were activated by MTP-Chol NC and interferon-gamma, TNF-alpha production seemed to act as a second messenger. Thus, under certain conditions, NO can play a role in modulating the cytotoxic activities of mouse macrophages.

Adjuvants, Immunologic↗
PubMedDate not supplied

A comparative study of the cellular uptake, localization and phototoxicity of meta-tetra(hydroxyphenyl) chlorin encapsulated in surface-modified submicronic oil/water carriers in HT29 tumor cells.

The poor selectivity of photosensitizers for tumor tissue remains a drawback in photodynamic therapy (PDT) and could be improved by adapted formulations. The cellular uptake, localization and phototoxicity of meta-tetra(hydroxyphenyl)chlorin (mTHPC) encapsulated in submicronic colloidal carriers have been studied in macrophage-like J774 cells and HT 29 human adenocarcinoma cells. Nanocapsules with an external layer made of poly(D,L lactic acid) (PLA NCs), PLA grafted with polyethylene glycol (PLA-PEG NCs), PLA coated with poloxamer 188 (polox PLA NCs) and oil/water nanoemulsion (NE) have been examined. The cellular uptake by J774, as determined by microspectroflorimetry, is reduced with mTHPC encapsulated into surface-modified NCs--PLA-PEG and polox PLA--compared with naked PLA, indicating a possible limitation of the clearance of such carriers by the reticuloendothelial system. Encapsulation also modifies the interaction between mTHPC and HT29 cells. Compared with the manufacturer's solution (PEG, ethanol, water), the cellular uptake is strongly reduced. However, the HT29 phototoxicity is much less affected and a protecting effect against plasma proteins is observed. Fluorescence microscopy reveals a specific punctate fluorescence pattern with PLA-PEG and polox PLA NCs in contrast to a more diffuse distribution with NE and solution, indicating that photodamage targeting could be different. These findings suggest that photosensitizers encapsulated into surface-modified nanocapsules could be a promising approach for improving PDT efficacy and this has to be confirmed in vivo.

Animals↗
PubMedDate not supplied

[What can a neurophysiologic examination contribute to phlebologists?].

After a theoretical summary and account of current techniques, the authors describe the 'electric symptomatology' of the lower limbs and suggest the pathologies in which the anomalies are to be located. The analysis of some personal clinical cases enables them, finally, to draw some practical conclusions: an NP check-up can easily be requested, is not traumatic, and should be considered (except in cases where a primary neurological pathology is suspected) when the clinical and paraclinical symptoms on the one hand, and functional disorders on the other, are dissociated. Emphasis should be placed on reduction of speed of conduction, provided that the examination is carried out by a trained specialist, preferably always the same one. Finally we think that metabolic disorders engendered by venous stasis are likely to be accompanied by neuritic-type degenerations which then develop on their own account; this will be the subject of a further study.

Aged↗