Biomedical subjects

V Barbier

Publications and source records attributed to V Barbier.

5 recordsLinked to original sources

PubMed2006

Producing droplets in parallel microfluidic systems.

We study the dynamics of two microfluidic droplets emitters placed in parallel. We observe complex dynamical behavior, including synchronization, quasiperiodicity, and chaos. This dynamics has a considerable impact on the properties of the resulting emulsions: chaotic and quasi-periodic regimes give rise to polydispersed emulsions with poorly controllable characteristics, whereas synchronized regimes generate well-controlled monodispersed emulsions. We derive a dynamical model that reproduces the trends observed in the experiment.

Journal Article↗

PubMed2006

Arnold tongues in a microfluidic drop emitter.

The Letter reports an experimental study of microfluidic droplets produced in T junctions and subjected to a local periodic forcing. Synchronized and quasiperiodic regimes--organized into Arnold tongues and devil staircases--are reported for the first time for a system dedicated to drop emission. The nature of the dynamical regime controls the droplet characteristics. These phenomena are mostly controlled by the characteristics of the forcing and the flow conditions.

Journal Article↗

PubMed2002

Aspergillus fumigatus causes in vitro electrophysiological and morphological modifications in human nasal epithelial cells.

The role of the airway epithelium in the development of invasive aspergillosis in immunocompromised hosts has rarely been studied although patients at risk for this infection frequently have epithelial damage. We developed an in vitro model of primary culture of human nasal epithelial cells (HNEC) in air-liquid interface, which allows epithelial cell differentiation and mimics in vivo airway epithelium. We subsequently tested 7-day and 24-hour Aspergillus fumigatus filtrates on the apical side of HNEC to know whether A. fumigatus, the main species responsible for invasive aspergillosis, produces specific damage to the epithelial cells. The results were compared with those obtained with non-pathogenic filamentous fungi. Seven-day culture filtrates of A. fumigatus and Penicillium chrysogenum induced electrophysiological modifications whatever the fungus tested. In contrast, only 24-hour A. fumigatus filtrates induced a specific decrease in transepithelial resistance, hyperpolarization of the epithelium, and cytoplasmic vacuolization of HNEC compared with both A. niger and Penicillium chrysogenum. The inhibition of the A. fumigatus effects with amiloride suggests that the 24-hour fungal filtrate acts through sodium channels of HNEC. These early modifications of the epithelial cells could facilitate colonization of the airways by A. fumigatus. To know whether the molecules involved are specific to A. fumigatus or simply produced more rapidly than by other filamentous fungi warrants further investigation. In this perspective, the primary culture of HNEC represents a suitable model to study the interactions between airway epithelial cells and A. fumigatus.

Amiloride↗

PubMed2001

New block-copolymer thermoassociating matrices for DNA sequencing: effect of molecular structure on rheology and resolution.

A new family of matrices for DNA sequencing by capillary electrophoresis is presented. These matrices combine easy injection with high sieving performances, due to thermal switching between a low and a high viscosity state through a modest increase in temperature (approximately 20 degrees C). They are constructed from a hydrophilic polymer backbone with grafted lower critical solution temperature (LCST) side chains. The comb-like LCST copolymers are characterized in terms of size of the polymer backbone, the size of LCST side chains and the grafting densities. The dependance of rheological behavior and electrophoretic performance of these copolymers is correlated with their microstructure. Without complete optimization, a resolution of order 0.5, corresponding to a very reasonable limit for read length with current base calling softwares, could be achieved for segments around 800 bases differing by 1 base in less than one hour in a commercial ABI 310 apparatus.

Acrylic Resins↗

PubMed2001

Neurologic outcomes of 90 neonates and infants with persistent hyperinsulinemic hypoglycemia.

OBJECTIVE: To evaluate the neurologic outcomes of neonates and infants suffering from persistent hyperinsulinemic hypoglycemia of infancy (PHHI). METHODS: The neurologic development of 90 PHHI patients was studied retrospectively. Sixty-three patients were treated surgically and 27 were treated medically. Fifty-four patients were neonates, of whom 8 were treated medically and 46 were operated on (19 for a focal adenomatous hyperplasia and 27 for diffuse hyperinsulinism). Thirty-six patients had infancy-onset hyperinsulinism, of whom 19 were treated medically and 17 underwent pancreatectomy (10 patients for a focal adenomatous hyperplasia and 7 for diffuse hyperinsulinism). RESULTS: Severe psychomotor retardation was found in 7 patients, 6 with neonatal-onset PHHI. Intermediate psychomotor disability existed in 12 patients; epilepsy existed in 16. Neonatal-onset was the main risk factor for severe retardation or epilepsy. Medically treated patients were less severely affected than those treated by surgery, and there was no difference between the diffuse and focal forms of hyperinsulinism. CONCLUSION: Neonatal hyperinsulinemic hypoglycemia is still a severe disease with an important risk to rapidly develop severe mental retardation and epilepsy.

Age of Onset↗