[Support care in paediatric oncology]

From the diagnosis of leukaemia and throughout the complex care pathway in paediatric oncology, nurses support the child and the parents, notably as part of the cross-disciplinary support care provided. They play a pivotal role within the multidisciplinary team and favour a personalised treatment helping the child-parent dyad cope better with the disease.

Methicillin-resistant Staphylococcus aureus (MRSA) with reduced susceptibility to glycopeptides (GISA) in 63 French general hospitals

Clinical isolates of methicillin-resistant Staphylococcus aureus (n = 1070) collected from 63 French general hospitals during June 2000 (n = 1070) were screened initially for reduced susceptibility to glycopeptides (GISA) on brain-heart infusion agar containing teicoplanin 6 mg/L. Glycopeptide MICs were determined for the 145 isolates that grew on the screening plates. Of the 1070 isolates, 1.4% were GISA on Mueller-Hinton agar, and 2.9% by Etest with a high inoculum, while 0.7% and 2.9% were GISA by vancomycin and teicoplanin population analysis profiles, respectively. Most isolates were resistant to gentamicin and rifampicin or fosfomycin or fusidic acid, as determined by disk diffusion. Pulsed-field gel electrophoresis of the 31 GISA isolates identified four clones, with dissemination of one predominant clone. In these French hospitals there was a low incidence of GISA and hetero-GISA.

Combined hydroxypropyl-beta-cyclodextrin and poly(alkylcyanoacrylate) nanoparticles intended for oral administration of saquinavir

The aim of this study was to prepare and characterize an hydroxypropyl-beta-cyclodextrin-saquinavir inclusion complex with the purpose of incorporating this complex into poly(alkylcyanoacrylate) nanoparticles in order to increase the drug loading. Hydroxypropyl-beta-cyclodextrin-saquinavir complex was characterized by thermal (differential scanning calorimetry), crystallographic (X-ray diffractography) and spectroscopic methods (circular dichroism, H1-NMR). Nanoparticles were prepared by polymerization of alkylcyanoacrylate monomers (isobutyl- and isohexylcyanoacrylate) in a water solution of the complex and further characterized. The apparent solubility of saquinavir was increased 400-fold at pH 7.0 in presence of hydroxypropyl-beta-cyclodextrin owing to the formation of a drug-cyclodextrin complex as demonstrated mainly by 1H NMR and confirmed by other techniques. Saquinavir-loaded nanoparticles could be easily prepared in the presence of a drug-cyclodextrin complex. It was found that large amounts of cyclodextrins remained associated with the particles, resulting in a 20-fold increase in saquinavir loading compared to nanoparticles prepared in the absence of cyclodextrins. This study has shown that the loading in saquinavir of poly(alkylcyanoacrylate) nanospheres could be dramatically improved by simultaneously increasing the apparent solubility of the drug in the preparation medium and the amount of cyclodextrin associated with the particles, making these nanospheres a promising system for oral application.

N-Methyl-N-D-fructosyl amphotericin B methyl ester (MF-AME), a novel antifungal agent of low toxicity: monomer/micelle control over selective toxicity

Rational chemical modification of amphotericin B (AMB) led to the synthesis of sterically hindered AMB derivatives. The selected optimal compound, N-methyl-N-D-fructosyl amphotericin B methyl ester (MF-AME) retains the broad spectrum of antifungal activity of the parent antibiotic, and exhibits a two orders of magnitude lower toxicity in vivo and in vitro against mammalian cells. Comparative studies of MF-AME and AMB comprising the determination of the spectroscopic properties of monomeric and self-associated forms of the antibiotics, the investigation of the influence of self-association on toxicity to human red blood cells, and of the antibiotic-sterol interaction were performed. On the basis of the results obtained it can be assumed that the improvement of the selective toxicity of MF-AME could in part be a consequence of the diminished concentration of water soluble oligomers in aqueous medium, and the better ability to differentiate between cholesterol and ergosterol.

N-Methyl-N-D-fructosyl amphotericin B methyl ester (MF-AME), a novel antifungal agent of low toxicity: monomer/micelle control over selective toxicity

Rational chemical modification of amphotericin B (AMB) led to the synthesis of sterically hindered AMB derivatives. The selected optimal compound, N-methyl-N-D-fructosyl amphotericin B methyl ester (MF-AME) retains the broad spectrum of antifungal activity of the parent antibiotic, and exhibits a two orders of magnitude lower toxicity in vivo and in vitro against mammalian cells. Comparative studies of MF-AME and AMB comprising the determination of the spectroscopic properties of monomeric and self-associated forms of the antibiotics, the investigation of the influence of self-association on toxicity to human red blood cells, and of the antibiotic-sterol interaction were performed. On the basis of the results obtained it can be assumed that the improvement of the selective toxicity of MF-AME could in part be a consequence of the diminished concentration of water soluble oligomers in aqueous medium, and the better ability to differentiate between cholesterol and ergosterol.

Probable transmission of HIV from an orthopedic surgeon to a patient in France

BACKGROUND

Transmission of HIV from infected health care workers to patients has been documented in only one cluster involving 6 patients of a dentist in Florida. In October 1995, the French Ministry of Health offered HIV testing to patients who had been operated on by an orthopedic surgeon in whom AIDS was recently diagnosed.

OBJECTIVE

To determine whether the surgeon transmitted HIV to patients during operations.

DESIGN

Epidemiologic investigation.

SETTING

The practice of an orthopedic surgeon in a French public hospital.

PARTICIPANTS

1 surgeon and 983 of his former patients.

MEASUREMENTS

3004 patients who had undergone invasive procedures were contacted by mail for counseling and HIV testing. One HIV-positive patient was interviewed, and DNA sequence analysis was performed to compare the genetic relation of the patient's and the surgeon's viruses. Infection-control precautions and the surgeon's practices were assessed.

RESULTS

Of 983 patients in whom serologic status was ascertained, 982 were HIV negative and 1 was HIV positive. The HIV-positive patient, a woman born in 1925, tested negative for HIV before placement of a total hip prosthesis with bone graft (a prolonged operation) performed by the surgeon in 1992. She had no identified risk for HIV exposure. Molecular analysis indicated that the viral sequences obtained from the surgeon and the HIV-infected woman were closely related. Infection-control precautions were in accordance with recommendations, but blood contact between the surgeon and his patients occurred commonly during surgical procedures.

CONCLUSIONS

An HIV-infected surgeon may have transmitted HIV to one of his patients during surgery.

Investigation of hospital-acquired infections due to Alcaligenes denitrificans subsp. xylosoxydans by DNA restriction fragment length polymorphism

We demonstrate that DNA restriction fragment length polymorphism determined by pulsed-field gel electrophoresis is very useful in the investigation of the epidemiology of hospital-acquired infections caused by Alcaligenes denitrificans subsp. xylosoxydans. This approach showed that hospital-acquired infections caused by this opportunistic pathogen over a 6-month period in 10 patients hospitalized in an intensive care unit and a surgical unit were not a true outbreak. In addition, this molecular typing method established that the respiratory therapy equipment was the source of the contamination of two patients.

Effect of surface curvature on the interaction of single lamellar phospholipid vesicles with aromatic and nonaromatic heptaene antibiotics (vacidin A and amphotericin B)

The interactions of unilamellar lipid vesicles with vacidin A, an aromatic heptaene antibiotic, and with amphotericin B, a nonaromatic heptaene antibiotic were compared. Uptake of both antibiotics, monitored by circular dichroism, was found to be faster with small vesicles than with large ones. By combining permeability measurements (Gary-Bobo and Cybulska, J. Antibiotics 35, 1068 (1982)) and circular dichroism spectra, we found that for vacidin A, the same permeability inducing species is formed regardless of vesicles size. However, at a given concentration of antibiotic, less of the permeability inducing species is formed in the presence of small vesicles than in the presence of large vesicles. This may account for the differences between small and large vesicles in antibiotics-induced permeability. For amphotericin B, the permeability inducing species formed in the presence of small vesicles differs from that formed in the presence of large vesicles.

Association of the polyene antibiotic amphotericin B with phospholipid vesicles: perturbation by temperature changes

Conformational changes of amphotericin B in the presence of cholesterol as well as in the presence of bilayer vesicles of phosphatidylcholine with saturated fatty acid chains of various lengths (14 less than n less than 22) have been monitored by circular dichroism (CD). It has been shown that the observed species are not only dependent on such parameters as the cholesterol content of the vesicles, the vesicles' physical state, and the number of amphotericin B molecules per vesicle, but also on the time elapsed after mixing and the thermal treatment of the system, which may create irreversible changes. In particular, heating through the transition temperature (Tc) vesicles containing cholesterol and loaded with amphotericin below Tc leads to the expulsion into the aqueous medium of a cholesterol-amphotericin complex, a phenomenon which affords an explanation for some of the electron paramagnetic resonance and resonance Raman results. It has also been shown by gel filtration, ultracentrifugation, and Tc determination that interaction of amphotericin B with vesicles in the gel state induces fusion or aggregation of the vesicles, which is not the case (or at least weakly) when the vesicles are in the liquid crystalline state. This aggregation is the more rapid the nearer the temperature of the reaction is to Tc. This study confirms the great complexity of events which may occur during interaction of amphotericin B with model membranes and presents some results which complement those of studies performed with other spectroscopic methods.