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Biomedical subjects

F Leroy

Publications and source records attributed to F Leroy.

At least 19 recordsLinked to original sources
PubMed2007

In vitro and in vivo confocal Raman study of human skin hydration: assessment of a new moisturizing agent, pMPC.

The hydration capacities of a biomimetic polymer, 2-methacryloyloxethylphosphorylcholine polymer (pMPC), alone and microencapsulated, in association with another well known hydrating polymer, Hyaluronic acid, were investigated in vitro on skin models and in vivo on volunteers by using confocal Raman microspectroscopy. The hydration impact and the relative water content in the Stratum corneum were calculated from the Raman spectra using the OH (water)/CH3 (protein) ratio. Moreover, the follow-up of the presence of pMPC through the Stratum corneum was possible with confocal Raman microspectroscopy, using a characteristic vibration of pMPC, different from that of the encapsulating material. From our in vitro measurements, the improved hydration of the Stratum corneum was confirmed by the use of the encapsulated form of pMPC, which was higher when combined with Hyaluronic acid. On the basis of these in vitro findings, we validated this trend in in vivo measurements on 26 volunteers, and found a good correlation with the in vitro results. Mechanical and ultrastructural studies have been carried out to demonstrate the positive effects of the pMPC on the Stratum corneum function, namely the interaction with lamellar lipids and the plasticizing effects, which are both supposed to spell out the moisturizing effect. This study demonstrates the efficiency of a original hydrating agent, pMPC, entrapped with Hyaluronic acid in a new type of microcapsules by the use of a novel tool developed for both in vitro and in vivo approaches. This indicates a new step to evaluate and improve new moisturizers in response to the cosmetics or dermatologic demands.

Adult↗
PubMed2006

An in vivo randomized study of human skin moisturization by a new confocal Raman fiber-optic microprobe: assessment of a glycerol-based hydration cream.

BACKGROUND: In a recent study, we demonstrated the ability of the new confocal Raman microprobe to investigate molecular and structural human skin composition under in vivo conditions. Experiments were performed at different anatomical sites, different layers, and with intervolunteer comparison. We also carried out feasibility tests using this probe to determine depth profiles of water content within the skin. OBJECTIVE: In the present investigation we employed this confocal Raman optical microprobe to rigorously objectify the resulting hydration capacities after application of a moisturizing enhancer. METHOD: The in vivo experiments were performed on 26 healthy volunteers and measurements were undertaken on six areas of the volar forearm after a randomized application of hydrating agents. Responses were evaluated by calculating the water/protein band ratio, which determines the water content in the skin. RESULTS: Data collected with the Raman microprobe showed significant changes between baseline values of control and treated skins. Statistical analysis performed on these data revealed an increase in skin moisture after application of a glycerol-based cream, which is the most widely used hydrating agent. CONCLUSION: Our results demonstrate clearly the potentials of this confocal Raman microprobe in the screening of hydrating agents or molecules under in vivo conditions. In the cosmetics field, this promising and suitable technique will undoubtedly offer new opportunities of hydration skin test evaluation.

Administration, Cutaneous↗
PubMed2006

Cytomegalovirus prophylaxis with intravenous polyvalent immunoglobulin in high-risk renal transplant recipients.

Cytomegalovirus (CMV) seronegative renal allograft recipients (R-), particularly those with a graft from a CMV-seropositive donor (D+), are at high risk for primary CMV infection. CMV resistance to antiviral oral therapy is an emerging problem in renal transplantation, prompting development of new prophylactic strategies. We retrospectively studied the 1-year posttransplantation incidence of CMV infection in high-risk renal transplant recipients, in whom polyvalent intravenous immunoglobulins (IVIg) were used as prophylaxis. Forty R- patients received immunoprophylaxis by polyvalent IVIg (0.25 g/kg weekly for 8 weeks, starting on the operative day). CMV serological tests remained negative in eight patients (20%). Eight patients (20%) had asymptomatic CMV infection while 24 (60%) developed CMV syndrome and were treated with gancyclovir (10 mg/kg/day intravenously for 3 weeks). None had CMV disease or opportunistic infection. Six patients (15%) had biopsy-proven acute rejection, which followed CMV syndrome in three cases. One-year renal allograft and patient survivals were 95% and 97.5%, respectively. Mean serum creatinine level was 124 +/- 33 micromol/L at 1 year. Clinical tolerance of IVIg was excellent, without any episode of acute renal failure. Polyvalent IVIg provides effective prophylaxis in renal transplant recipients at high risk for CMV infection and is associated with excellent 1-year allograft survival. Because of their immunomodulatory functions, IVIg may have a beneficial effect on the incidence of acute and chronic rejection and allograft survival. A randomized prospective study is required to evaluate long-term effects of CMV prophylaxis with polyvalent IVIg compared to antiviral agents in renal transplant recipients.

Cytomegalovirus Infections↗
PubMed2005

Self-organized growth of nanoparticles on a surface patterned by a buried dislocation network.

The self-organized growth of Co nanoparticles is achieved at room temperature on an inhomogenously strained Ag(001) surface arising from an underlying square misfit dislocation network of 10 nm periodicity buried at the interface between a 5 nm-thick Ag film and a MgO(001) substrate. This is revealed by in situ grazing-incidence small-angle x-ray scattering. Simulations of the data performed in the distorted wave Born approximation framework demonstrate that the Co clusters grow above the dislocation crossing lines. This is confirmed by molecular dynamic simulations indicating preferential Co adsorption on tensile sites.

Journal Article↗
PubMed2005

Synthesis of 5-aza-7-deazaguanine nucleoside derivatives as potential anti-flavivirus agents.

Coupling suitable sugars (D- or L-ribofuranose, 2' or 3-deoxysugar, branched sugars) with 2-aminoimidazo[1,2-a]-s-triazin-4-one was carried out using the different reaction conditions: 1) condensation in the presence of sodium hydride; or 2) condensation using Vorbrüggen's methods. The 5-aza- 7-deazaguanine nucleoside analogues obtained were evaluated in cell culture experiments for the inhibition of the replication of a number of RNA viruses, including BVDV, YFV, and WNV.

Antiviral Agents↗
PubMed2004

[Ten years follow-up of medically assisted procreation in Belgium].

Since 1989, the data concerning medically assisted procreation (MAP) in Belgium have been registered through the BELRAP association (Belgian Register for Assisted Procreation). In 1999, the national College of Physicians in Reproductive Medicine has been installed and given the mission to carry out the quality controls and the registration of MAP activities in our country. In 2001, a new on line system of registration of all treatment cycles was started, the basic structure of the corresponding data base having undergone a series of changes along the years. Although the number of MAP trials has considerably increased in our country, mainly because of the introduction of new techniques such as intracytoplasmic injection of sperm (ICSI), the success rate per trial has remained almost unchanged, becoming stabilized around 18.8% of ongoing pregnancies per initiated cycle. The main modification that occurred during the analyzed period has been the reduction of the number of embryos transferred at each trial, being first reduced from 3 to 2 to evolve more recently towards the replacement of only one embryo per trial. Multiple pregnancies are indeed the chief complication of MAP and in order to avoid it Belgian centers have been among the first to reduce drastically the number of transferred embryos. In 2003, legal rules were enacted, fixing the number of replacable embryos in accordance to the patient's age and to the rank of trial, while also solving the problem of the long-awaited reimbursement of MAP by our national social security system.

Belgium↗
PubMed2003

Enterococcus faecium RZS C5, an interesting bacteriocin producer to be used as a co-culture in food fermentation.

Enterocins, bacteriocins produced by enterococci, are gaining interest because of their industrial potential. Due to its bacteriocin production, Enterococcus faecium RZS C5, a natural cheese isolate, has a strong activity towards Listeria monocytogenes. For this reason, the strain may be applicable as a bacteriocin-producing co-culture in food fermentation in order to reduce the risk on Listeria outgrowth. The strain displays remarkable bacteriocin production kinetics. Whereas most lactic acid bacteria produce bacteriocin in a growth-associated way until the beginning of the stationary phase, bacteriocin production by E. faecium RZS C5 in MRS broth at controlled pH values below 7.5 is characterised by a boost of bacteriocin activity levels in the very early growth phase. In addition, bacteriocin production kinetics are closely linked to the environmental and cultural conditions. However, no straightforward statement about the effect of environmental stress on bacteriocin production can be made since the effect is dependent on the type of stress applied. Kinetic experiments in milk and on pilot scale, applying Cheddar cheese-making conditions, have indicated that the strain may be effective as a bacteriocin-producing co-culture. Further research is needed to evaluate the use of E. faecium RZS C5 as a co-culture for the production of fermented sausage.

Animals↗
PubMed2003

[Reflux nephropathy and arterial hypertension].

This case-report emphasizes an uncommon cause of hypertension in an adolescent: reflux nephropathy. Reflux nephropathy is a frequent hypertension and renal failure etiology. Medical treatment is unknown from cardiologist.

Adolescent↗
PubMed2003

Current research on ethnic hair.

This study collected qualitative and quantitative data about the morphology, structure, geometry, water swelling, and mechanical properties of hair fibers from subjects of different ethnic origins. X-ray analysis, cross-sectional measurements, tensile testing, and water swelling were performed on samples of hair collected from Caucasian, Asian, and African subjects. No differences in the intimate structures of fibers were observed among these 3 types of hairs, whereas geometry, mechanical properties, and water swelling differed according to ethnic origin. In addition, the behavior of hair fiber under mechanical stress was visualized with environmental scanning electron microscopy.

Ethnicity↗
PubMed2002

Soret coefficient for liquid argon-krypton mixtures via equilibrium and nonequilibrium molecular dynamics: a comparison with experiments.

The Soret and the other transport coefficients, characterizing the heat and mass transport in binary mixtures, have been obtained by equilibrium and nonequilibrium molecular dynamics (EMD and NEMD, respectively). Two state points of the argon-krypton mixture are considered, for which experimental values of the Soret coefficient are available. To attempt a comparison between simulations and experiments the common enthalpy-diffusion-free expression for the heat flux has been chosen. The comparison of the simulations with the experiments shows a remarkable agreement, for all the several utilized EMD and NEMD techniques (dynamical and stationary). The techniques, used over 0.3 micros of total simulation time span, are slow convergent but have comparable performances.

Journal Article↗
PubMed2002

A new deformation model of hard alpha-keratin fibers at the nanometer scale: implications for hard alpha-keratin intermediate filament mechanical properties.

The mechanical behavior of human hair fibers is determined by the interactions between keratin proteins structured into microfibrils (hard alpha-keratin intermediate filaments), a protein sulfur-rich matrix (intermediate filaments associated proteins), and water molecules. The structure of the microfibril-matrix assembly has already been fully characterized using electron microscopy and small-angle x-ray scattering on unstressed fibers. However, these results give only a static image of this assembly. To observe and characterize the deformation of the microfibrils and of the matrix, we have carried out time-resolved small-angle x-ray microdiffraction experiments on human hair fibers stretched at 45% relative humidity and in water. Three structural parameters were monitored and quantified: the 6.7-nm meridian arc, which is related to an axial separation between groups of molecules along the microfibrils, the microfibril's radius, and the packing distance between microfibrils. Using a surface lattice model of the microfibril, we have described its deformation as a combination of a sliding process and a molecular stretching process. The radial contraction of the matrix is also emphasized, reinforcing the hydrophilic gel nature hypothesis.

Hair↗
PubMed2001

Sequential activation brain mapping after subcortical stroke: changes in hemispheric balance and recovery.

We prospectively studied 5 patients while they were recovering from left-sided subcortical stroke affecting the cortico-spinal tract, and examined them twice with H(2)(15)O-PET over several months while performing an identical task with the affected hand. Concomitant motor recovery was assessed by measuring the number of thumb-to-index tappings performed in 15 s at each PET session. Across patients, the hemispheric activation balance tended to shift over time toward the unaffected hemisphere, but the magnitude of this shift was highly variable from patient to patient and significantly correlated with recovery. Thus, in subcortical stroke, a shift of activation balance towards the unaffected hemisphere appears associated with lesser initial recovery and, conversely, the more this physiological balance is maintained over time the better the recovery.

Brain Mapping↗
PubMed2001

Fast generic-gradient reversed-phase high-performance liquid chromatography using short narrow-bore columns packed with small nonporous silica particles for the analysis of combinatorial libraries.

The extremely large number of samples generated for the quality control analysis of combinatorial libraries that are developed in the pharmaceutical research for drug discovery requires fast generic methods such as rapid-gradient reversed-phase high-performance liquid chromatography (HPLC). These methods are necessary as standard procedures to produce up to several hundreds of analytical results per day and should be optimized in order to be applied to library products of widely differing polarities. This work presents an optimized generic method using a narrow-bore column packed with 1.5-microm nonporous particles and a completely automated HPLC workstation configured for the best efficiency, throughput, and robustness with this column. A test mix of 12 compounds with a wide polarity range is separated within 1.5 min with a cycle time of 3.5 min. The throughput is further enhanced using a Gilson 233XL dual-injection sampler to feed two parallel HPLC systems in order to perform 34 analyses per hour.

Chemistry, Pharmaceutical↗