Biomedical subjects

F Puisieux

Publications and source records attributed to F Puisieux.

At least 73 records · Page 4Linked to original sources

PubMed1994

Mucoadhesion of latexes. II. Adsorption isotherms and desorption studies.

Adsorption isotherms of poly(styrene) latexes on rat intestinal mucosa were studied under static conditions and analyzed according to different isotherm classifications. Isotherms of latexes with a particle size up to 670 nm had the characteristic shape of a disperse adsorbate on a porous adsorbent. Plateaus were reached at latex concentrations of about 2.5 g/L. The results indicated an increase in adsorption with the size and the hydrophilicity of the latexes. Typically, a surfactant-free carboxylate latex of 230 nm had a plateau of 0.66 g/m2, and a latex of 320 nm with added sodium dodecyl sulfate had a plateau of 0.881 g/m2. Surfactant-free carboxylate latex of 2 microns had a Langmuirian isotherm with a plateau level of 2.616 g/m2, which corresponded to a monolayer of adsorbed particles on the surface of mucosa. Desorption studies showed that the adsorption was irreversible. Adhesion to the mucous gel layer would therefore be limited by the mucus turnover.

Adsorption↗

PubMed1994

Adsorption of oligonucleotides onto polyisohexylcyanoacrylate nanoparticles protects them against nucleases and increases their cellular uptake.

Oligonucleotides can be adsorbed on polyisohexylcyanoacrylate nanoparticles in the presence of hydrophobic quarternary ammonium salts. Oligonucleotides bound to nanoparticles are protected from nuclease attack both in buffer and in cell culture media. Cellular uptake of oligonucleotides is increased when they are adsorbed onto nanoparticles as a result of the capture of nanoparticles by an endocytic phagocytic pathway. Intracellular stability towards nucleolytic degradation is increased in the presence of nanoparticles. These results show that nanoparticles can be considered as convenient carriers for the protection and delivery of oligonucleotides to cells.

Adsorption↗

PubMed1994

Mucoadhesion of latexes. I. Analytical methods and kinetic studies.

A Fourier transform infrared spectroscopy/attenuated total reflection technique for direct quantification of adsorbed poly(styrene) latexes on rat intestinal mucosa was developed for deposited latex amounts up to 1.5 g/m2. The method agreed well with another dosage assay of adsorbed particles by turbidimetry after denaturation of the mucus. Adsorption kinetics were made under static conditions at latex concentrations of 4 g/L in physiological saline. Ninety percent of equilibrium was reached after 10 min for a particle size of 230 nm, 20 min for a size of 320 nm, and 30 min for a size of 670 nm. The plateaus were between 0.6 and 0.9 g/m2 (adsorbed mass per apparent surface of mucosa). The first phase of the kinetics was theoretically approached by a diffusion model in the suspension medium. Mucosa from rat jejunum and ileum could be considered as a homogeneous biological model for latex adsorption.

Adsorption↗

PubMed1994

Intracellular visualization of ampicillin-loaded nanoparticles in peritoneal macrophages infected in vitro with Salmonella typhimurium.

Intracellular targeting of ampicillin by means of polyisohexylcyanoacrylate (PIHCA) nanoparticles was studied in murine peritoneal macrophages infected with Salmonella typhimurium. The intracellular distribution of actively endocytosed nanoparticles was visualized by transmission electron microscopy and confocal microscopy. Nanoparticles were either isolated or closely associated with bacteria within phagosomes or phagolysosomes. Thus the potential of ampicillin-loaded nanoparticles in targeting of intracellular bacteria is demonstrated. Consequently, ampicillin, which usually penetrates into cells at a low level, is directly carried in, when loaded on nanoparticles, and brought into contact with intracellular bacteria.

Ampicillin↗

PubMed1994

Optimization and characterization of freeze-dried multilamellar liposomes incorporating different standardized allergen extracts.

Desensitization therapy for type I allergy is now current practice. Liposomes have been proposed as a support for allergens to improve safety and effectiveness. The aim of this work was to optimize liposomal formulations of three different standardized allergen extracts and to test their allergenicity in vitro and in a preclinical trial. Allergen extracts (Dactylis glomerata, Dermatophagoides pteronyssinus, and cat hair and dander) were associated with multilamellar liposomes of varying compositions at different pH. Liposome-bound allergens were quantified by RAST inhibition after ultracentrifugation, and analyzed qualitatively by SDS-PAGE followed by immunoblotting. Their allergenicity was assessed by basophil degranulation in vitro, as compared with the allergenicity of an aqueous extract, and by skin tests in allergic subjects. The best association, about 50% of the added allergen, was obtained with negatively charged liposomes, when the pH of the allergen solution was adjusted so as to impart a net positive charge to the proteins. One-third of the liposome-associated allergens was located on the surface of the liposomes and was free to interact with antibody, as shown by RAST inhibition assays and the basophil degranulation test; the remaining two-thirds was encapsulated within the liposomes. All the major immunoreactive proteins in the extract were included. These liposomes could be readily freeze-dried and reconstituted without changing their properties. This study reveals the allergenic characteristics of liposomes and suggests their potential use in the treatment of allergic patients.

Allergens↗

PubMed1994

Liposomes, an interesting tool to deliver a bioenergetic substrate (ATP). in vitro and in vivo studies.

Adenosine triphosphate (ATP) was proposed in various medical applications, as a possible bioenergetic substrate. Unfortunately, ATP is very difficult to use at a therapeutic level because of its high sensitivity to enzymatic hydrolysis making this molecule unstable in biological fluids. ATP is also a highly hydrophilic molecule that is unable to cross biological membranes. To try to develop a system able to protect ATP against degradation and to efficiently deliver this bioenergetic substrate, its liposomal encapsulation in multilamellar vesicles was carried out. One of the studies described in this paper deals with the efficiency of liposomal ATP in the treatment of cerebral ischemia. Our results show that encapsulation was able to protect ATP from its degradation by ectonucleotidases and that liposomal ATP was active against experimental brain ischemia. The other study deals with the effect of ATP on the motility and the acrosomal reaction of human spermatozoa. The results show that co-incubating ATP-loaded liposomes with sperm cells was able to induce the process of capacitation in vitro and might therefore be a useful tool in the procedure of in vitro fertilization.

Adenosine Triphosphate↗

PubMed1993

Development of a new drug carrier made from alginate.

A new approach for the preparation of nanoparticles is presented. The method is based on control of the gelification phenomenon of alginate by calcium ions, and it leads to small particles of a wide range of very well-defined sizes (250-850 nm) depending on the alignate concentration. The particles are formed in a sodium alginate solution by addition of calcium chloride and then poly-L-lysine. The concentrations of sodium alginate and of calcium chloride were lower than those required for gel formation and corresponded to the formation of a pregel state. The size of the particles formed is greatly dependent on the order of addition of calcium and poly-L-lysine to the sodium alginate solution. This phenomenon can be attributed to the difference in the nature of the interactions between calcium and alginate and between poly-L-lysine and alginate. Furthermore, the data indicate that the formation of the particles probably occurs during the addition of the first component to the sodium alginate solution. Evaluation of the drug-loading capacity was done with doxorubicin as a drug model. The results indicate that alginate nanoparticles are interesting carriers because the drug-loading capacity could be > 50 mg of doxorubicin per 100 mg of alginate.

Alginates↗

PubMed1993

[Prophylactic antibiotherapy using cefapirin in the surgery of duodenal ulcer: a randomized clinical trial].

A randomized clinical trial of antibiotic prophylaxis in patients undergoing gastroduodenal surgery for stenosing or bleeding duodenal ulcer was carried out from February 1990 to February 1991. Seventy-two patients were randomly assigned to either Group I (n = 33) and given 1 g of cefapirine intravenously every eight hours, four times, starting at induction of anaesthesia; or to Group II (n = 39), and not given any antibiotic. The surgical dressing was changed on the third postoperative day, and thereafter every two days in patients with fever. The efficiency of prophylaxis was assessed on the incidence of superficial or deep primary infection, and the length of hospital stay. Primary wound sepsis occurred in 7 Group II patients, and in none in Group I (n = 0.01). The results for those patients with stenosing ulcer (n = 53) were also significant: there was no primary wound infection in Group I (n = 25), whereas five occurred in Group II (n = 28) (p = 0.03). Hospital stay was shorter in Group I than in Group II (7 vs 9.5 days). Antibiotic prophylaxis also seemed to be efficient in patients with bleeding duodenal ulcers (n = 19), but their group was too small to reach levels of statistical significance. Again hospital stay was shorter in Group I than in Group II (8.5 vs 12.2 days). The efficiency of antibiotic prophylaxis was therefore confirmed for patients undergoing gastroduodenal surgery for stenosing duodenal ulcer.

Adult↗

PubMed1993

Biodegradable nanocapsules containing a lipophilic immunomodulator: drug retention and tolerance towards macrophages in vitro.

Nanocapsules (250 nm diameter) were prepared from poly (D, L-lactide) containing a lipophilic immunomodulator: MDP-L-alanyl cholesterol (MTP-Chol). High encapsulation rates were obtained at 37 degrees C in culture medium or in buffers imitating phagosomes and lysosomes. The tolerance of these particles by rat alveolar macrophages in vitro was tested. A slight toxicity was observed which was the result of two factors: the capacity of the immunomodulator to stimulate the generation of nitrite oxide by the L-arginine-dependent pathway and the polymer itself. The latter toxicity seemed to be mediated by a different mechanism.

Acetylmuramyl-Alanyl-Isoglutamine↗

PubMed1993

Multiple emulsions.

The purpose of this review is to update the information on multiple emulsions known to be promising delivery systems for both pharmaceuticals and cosmetic materials. The possibility of encapsulating active substances within liquid membranes may lead to interesting opportunities in both fields. Thus the formulation, manufacturing, stabilization, analysis and potential application of multiple emulsions seems to be worth surveying, putting a special emphasis on cosmetic applications.

Chemistry, Pharmaceutical↗

PubMed1992

Determination of phospholipids from pulmonary surfactant using an on-line coupled silica/reversed-phase high-performance liquid chromatography system.

A basic normal-phase HPLC separation of phospholipids can be improved by introducing a limited contribution of solvophobic retention. For this purpose, the effect of an additional alkylsilica (C18) column of variable length coupled in series with a silica column was investigated. With increasing percentage of reversed phase in this system, the retention of phosphatidylglycerol increased. Phosphatidylinositol and phosphatidylserine were separated into molecular species. The "selective retention" defined in this study permits an evaluation of the solvophobic retention of phospholipids in the coupled system. An alternative column switching procedure is used for specific applications of the biphasic separation on chosen phospholipids. With this system, determination of phosphatidylglycerol and six other phospholipids from pulmonary surfactant could be performed.

Animals↗

PubMed1992

Polyalkylcyanoacrylate nanoparticles as polymeric carriers for antisense oligonucleotides.

Adsorption of oligothymidylates on polyisobutyl- or polyisohexylcyanoacrylate nanoparticles was achieved in the presence of hydrophobic cations such as tetraphenylphosphonium chloride or quaternary ammonium salts. Results suggested that oligonucleotide adsorption on the nanoparticles was mediated by the formation of ion pairs between the negatively charged phosphate groups of the nucleic acid chain and the hydrophobic cations. The adsorption efficiency of oligonucleotide-cation complexes on nanoparticles was found to be highly dependent upon several parameters: oligonucleotide chain length, nature of the cyanoacrylic monomer, hydrophobicity of cations used as ion-pairing agents, and ionic concentration of the medium. Carrier capacity of polyisohexylcyanoacrylate nanoparticles for oligothymidylates (16 nucleotides) complexed with cetyltrimetylammonium bromide in the presence of 0.15 M NaCl was determined to be 5 mumol/g polymer. The in vitro protection of oligothymidylates adsorbed to nanoparticles against degradation by a 3'-exonuclease (snake venom phosphodiesterase) was also demonstrated. These results showed that nanoparticles can be considered as convenient carriers for the protection and delivery of oligonucleotides to cells in culture and for future applications in vivo.

Cyanoacrylates↗

PubMed1992

[Stabilization and function of liposomes].

Liposomes stability can be improved by covering them with polysaccharide derivatives. The anchoring mechanism of these derivatives into the lipid membrane has been studied and explained. In order to improve liposome specificity, protein transfer from erythrocytes and platelets into liposome membrane has been carried out. The effect of a newly developed phospholipid, DDPC, on the efficiency and the selectivity of protein transfer is reported.

Blood Platelets↗

PubMed1992

Synthesis of the orally macrofilaricidal and stable glycerolipidic prodrug of melphalan, 1,3-dipalmitoyl-2-(4'(bis(2''-chloroethyl)amino)phenylalaninoyl)gl ycerol.

A new strategy is presented to develop macrofilaricidal compounds orally administered and able to concentrate in the lymphatic system. A diglyceride derivative of melphalan, 1,3-dipalmitoyl-2-(4'(bis(2''-chloroethyl)amino)phenylalaninoyl)gl y cerol, was synthesized. The esterification of melphalan by 1,3-dipalmitin allowed chemical stabilization of the alkylating agent in aqueous dispersion. No degradation of this prodrug was observed after a 3-month storage of an aqueous dispersion at 4 degrees C. The filaricidal activity of the prodrug was compared with those of melphalan in vitro against adults, infective larvae and microfilariae of Molinema dessetae, and evaluated in vivo on Molinema dessetae infected Proechimy oris. In vitro, melphalan and the glycerolipidic prodrug were inactive against microfilariae but active at 1 mmol/l against infective larvae and adults. In vivo studies were performed with rodents subcutaneously inoculated with infective larvae from Aedes aegypti. The number of macrofilariae was significantly reduced following treatment with a single oral dose of the alkylating agent prodrug (0.082 mmol/kg).

Aedes↗

PubMed1992

[Determination of an intrinsic value of diffusion coefficient of active principle in polymeric matrix for the formulation of a controlled release system].

The study of diffusion in a polymeric system often poses difficult experimental problems, notably when the rate of release is determined in a liquid receptor phase which can interact with the system. In this publication, we propose two experimental methods to determine the diffusion coefficient by a gel-gel kinetic release study, in which the receptor is a same gel unloaded initially. The first method is based on the use of radioactive tracers and a multi-channel radioactivity counter to obtain, at different times, the concentration profiles in the diffusion medium. The theoretical model is given for a gel donor with the concentration C0 of diffusing molecules is below or above the solubility Cs. The second method is based on the measurement of the displacement of solubility front during the diffusion within the system in the case C0 > Cs. The theoretical model shows that this displacement is a function of square root of t. For illustration, two experimental determinations of testosterone diffusion coefficient on the one hand in a silisic acid gels and on the other hand in an acrylic acid gels are given.

Immunodiffusion↗

PubMed1991

A structural study of interfacial phospholipid and lung surfactant layers by transmission electron microscopy after Blodgett sampling: influence of surface pressure and temperature.

Monolayer studies of the lung surfactant extract (LSE), dipalmitoyl phosphatidilcholine (DPPC) and dioleyl phosphatidilcholine (DOPC) have been performed in the dynamic condition at various temperatures. These compounds were also studied by differential scanning calorimetry, and the Langmuir Blodgett films were examined by electron microscopy. The combination of these techniques allowed us to describe precisely the collapse process, which was found to be different above and below the transition temperature of the lipids. However, whereas a phase separation for DPPC/DOPC mixtures occurred at all temperatures studied, this separation was observed for LSE only at temperatures lower than that characteristic of the "rigid state" to "liquid-like state" transition temperature. The ability of LSE to rapidly respread upon decompression appears to be due to the formation of piled amorphous aggregates formed during compression of its monolayers.

1,2-Dipalmitoylphosphatidylcholine↗

PubMed1991

Anti-metastatic activity in vivo of MDP-L-alanyl-cholesterol (MTP-Chol) entrapped in nanocapsules.

A lipophilic muramylpeptide (MTP-Chol), capable of rendering macrophages cytostatic towards tumour cells, was encapsulated within polyisobutylcyanoacrylate nanocapsules and administered to mice carrying an experimental model of liver metastasis. Treatment by intravenous injections twice a week beginning before the establishment of metastases significantly reduced the number of liver colonies. Treatment started later was less effective. The dose of MTP-Chol in each injection, and the tumour burden in the mice did not change the percentage inhibition of metastases significantly. Anti-metastatic activity was also observed after administering nanocapsules containing MTP-Chol by the oral route.

Acetylmuramyl-Alanyl-Isoglutamine↗

PubMed1991

Efficiency of liposomal ATP in cerebral ischemia: bioavailability features.

This study was performed to elucidate the mechanism by which adenosine triphosphate (ATP) encapsulated into liposomes was able to protect against experimental brain ischemia in the rat. After intracarotidal administration of liposomally entrapped ATP, the ATP blood level increased dramatically whereas no change was observed after administration of free ATP. This suggested that liposomes may protect ATP from its degradation by endothelial ectonucleotidases. On the other hand, it was observed that after administration of liposomally entrapped carboxyfluorescein (CF) to ischemic rats, the distribution of the brain fluorescence under the form of numerous punctiform structures was completely different from the diffuse fluorescence obtained with free CF injections. These data suggest that under certain hypoxic conditions the blood-brain barrier is open allowing the liposomes to reach the cerebral parenchyma. The mechanism of brain uptake is, however, still unclear: endothelial tight junctions opening or endothelial transcytosis.

Adenosine Triphosphate↗