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Biomedical subjects

E Fattal

Publications and source records attributed to E Fattal.

62 records · Page 4Linked to original sources
PubMed1989

Treatment of experimental salmonellosis in mice with ampicillin-bound nanoparticles.

We tested the effectiveness of ampicillin bound to nanoparticles of polyisohexylcyanoacrylate (PIHCA) in treating C57BL/6 mice experimentally infected with Salmonella typhimurium C5. The diameter of the nanoparticles was 187 +/- 13 nm, and the ampicillin/PIHCA ratio was 0.2/1. The proportion of ampicillin bound was 90 +/- 3%. All control mice and all those treated with nonloaded nanoparticles died within 10 days of infection. By contrast, all mice treated with a single injection of 0.8 mg of nanoparticle-bound ampicillin survived. With free ampicillin, a similar curative effect required three doses of 32 mg each. Lower doses delayed but did not reduce mortality. The sharp increase in the therapeutic index of ampicillin after linkage to PIHCA nanoparticles was explained by studies of the distribution of ampicillin, which showed that when bound to nanoparticles, the ampicillin was concentrated mainly in the liver and spleen, the primary foci of infection in the experimental model that we used. These findings warrant further development of intracellular targeting of antibiotics on biodegradable polymeric carriers such as PIHCA.

Ampicillin↗
PubMed1988

Liposomally entrapped adenosine triphosphate. Improved efficiency against experimental brain ischaemia in the rat.

Liposomally entrapped adenosine triphosphate (ATP) was administered intracerebroventricularly and intracarotidally to rats subjected to brain ischaemic episodes by clamping of the carotid arteries and lowering of the systemic blood pressure. It was observed that, when entrapped in liposomes, ATP greatly increased the number of ischaemic episodes before brain electrical silence and death. The results open new perspectives in brain ATP supply, which will potentially be useful in human resuscitation from deep brain hypoergic states.

Adenosine Triphosphate↗
PubMed1988

Intracarotidal administration of liposomally-entrapped ATP: improved efficiency against experimental brain ischemia.

ATP entrapped into liposomes was administered intracarotidally to rats submitted to brain ischemics episodes by clamping of the carotid arteries and lowering of the systemic blood pressure. It was observed that when entrapped into liposomes, ATP greatly increased the number of ischemic episodes tolerated before brain electrical silence and death appeared. These results added to very similar previous data obtained by i.c.v. treatment excluding the prominent role of cardiovascular effects, could open new possibilities in brain antihypoxic protection. Here and now it cannot be stated if ATP provides direct energetic supply.

Adenosine Triphosphate↗
PubMed1988

Effectiveness of nanoparticle-bound ampicillin in the treatment of Listeria monocytogenes infection in athymic nude mice.

The effectiveness of nanoparticle-bound ampicillin was tested in the treatment of experimental Listeria monocytogenes infection in congenitally athymic nude mice. Nanoparticles of polyisohexylcyanoacrylate (PIHCA) 187 +/- 13 nm in diameter were bound to ampicillin at an ampicillin/PIHCA ratio of 0.2:1. The proportion of ampicillin bound was 90% +/- 3%. After adsorption onto nanoparticles, the therapeutic activity of ampicillin increased dramatically over that in the free state. Thus, 2.4 mg of nanoparticle-bound ampicillin (three doses of 0.8 mg each) had a greater therapeutic effect than 48 mg of free ampicillin (three doses of 16 mg each). These results might provide an incentive for further development of intracellular targeting of antibiotics on biodegradable polymeric carriers.

Ampicillin↗
PubMed1987

Liposomally-entrapped ATP: improved efficiency against experimental brain ischemia in the rat.

ATP was entrapped inside negatively charged liposomes composed of sulfatide, in order to improve its penetration into the brain and to reduce its degradation into other tissues. These liposomes were prepared according to an original method allowing a satisfying stability of the formulation. Liposomally entrapped ATP was administered intracerebroventricularly to rats submitted to brain ischemic episodes by both carotid artery clamping and systemic blood pressure lowering (during 3 minutes every 15 minutes). Such treatment importantly increases the number of ischemic episodes before brain silence appeared. So, this paper allows new perspectives in the administration of drugs into the brain.

Adenosine Triphosphate↗
PubMedDate not supplied

Ampicillin-loaded liposomes and nanoparticles: comparison of drug loading, drug release and in vitro antimicrobial activity.

In this paper, we report the physico-chemical properties of negatively charged liposomes and of polyisohexylcyanoacrylate nanoparticles loaded with ampicillin. Although the carriers were of the same size (200 nm), drug-loading capacity was 20 times higher for nanoparticles than for liposomes. After freeze-drying or storage at +4 degrees C, no drug escaped from polymeric nanoparticles. On the other hand, in the same conditions, ampicillin leaked rapidly from liposomes. Drug release in foetal calf serum was gradual (of zero order) with nanoparticles, whereas it was rapid with liposomes. Finally, the antimicrobial activity of ampicillin-entrapped liposomes or nanoparticles was studied in vitro.

Ampicillin↗
PubMedDate not supplied

Changing the pH of the external aqueous phase may modulate protein entrapment and delivery from poly(lactide-co-glycolide) microspheres prepared by a w/o/w solvent evaporation method.

The milk model protein, beta lactoglobulin (BLG), was encapsulated into microspheres prepared by a multiple emulsion/solvent evaporation method. The effect of the pH of the outer aqueous phase on protein encapsulation and release as well as on microsphere morphology has been investigated. At all tested pH values, the encapsulation efficiency was shown to decrease with increasing the initial amount of BLG. This was correlated with the reduced stability of the primary emulsion as the initial BLG increased. In addition, reducing the solubility of BLG in the external aqueous phase by decreasing the pH to the isoelectric point of BLG (pI 5.2) resulted in an improved protein encapsulation. Moreover, it was shown that combining pH modification and optimal stability of the first emulsion yielded microspheres with a high encapsulation efficiency. However, release kinetic studies revealed that a significant burst release was observed with microspheres loaded with large amounts of BLG, especially when prepared in a medium at pH 5.2. This burst effect was attributed to morphology changes in the microsphere surface which was characterized by the presence of pores or channels able to accelerate the release of BLG. These pores were assumed to result from the presence of large amounts of protein molecules on the microsphere surface, that aggregate during microsphere formation at pH 5.2. Indeed, single adsorption experiments have shown that BLG had a higher affinity for the particle surface when the pH was close to the pI. Thus, reducing the solubility of a protein in the external aqueous phase allows the product of microspheres with a better encapsulation efficiency, although this benefit is provided by a strong adsorption of the protein on microsphere surface.

Adsorption↗