Transport of small anionic and neutral solutes through chitosan membranes: Dependence on cross-linking and chelation of divalent cations

Chitosan membranes were prepared by solvent casting and cross-linked with glutaraldehyde at several ratios under homogeneous conditions. The cross-linking degree, varying from 0 to 20%, is defined as the ratio between the total aldehyde groups and the amine groups of chitosan. Permeability experiments were conducted using a side-by-side diffusion cell to determine the flux of small molecules of similar size but with different chemical moieties, either ionized (benzoic acid, salicylic acid, and phthalic acid) or neutral (2-phenylethanol) at physiological pH. The permeability of the different model molecules revealed to be dependent on the affinity of those structurally similar molecules to chitosan. The permeability of the salicylate anion was significantly enhanced by the presence of metal cations commonly present in biological fluids, such as calcium and magnesium, but remained unchanged for the neutral 2-phenylethanol. This effect could be explained by the chelation of metal cations on the amine groups of chitosan, which increased the partition coefficient. The cross-linking degree was also correlated with the permeability and partition coefficient. The change in the permeation properties of chitosan to anionic solutes in the presence of these metallic cations is an important result and should be taken into consideration when trying to make in vitro predictions of the drug release from chitosan-based controlled release systems

La micropolyangéite: une histoire souvent en deux temps. [Microscopic polyangiitis: an unusual case report]

A 56-year-old woman was referred to our hospital because persistence of fever and inflammatory syndrome after antibiotic treatment for pneumonia. In the past, no special feature. Physical examination revealed only--at first--a pneumonia. Two weeks after, associated with the cough, she developed an acute renal failure. The laboratory revealed an inflammatory syndrome associated with proteinuria, hematuria and anti-neutrophil cytoplasmic antibodies. The CT of thorax shows aspecific infiltrations. The renal biopsy, in the context of the patient, diagnosed an microscopic polyangiitis. All the symptom resolved with the initiation of corticoid and cyclophosphamide treatment

Rabies in a nine-year-old child: The myth of the bite

A nine-year-old boy died from rabies encephalitis caused by a rabies virus variant associated with insectivorous bats. The patient was most likely infected in the Laurentian Mountains of western Quebec, but neither the patient nor his parents remembered any direct contact with an animal. The diagnosis was made seven days after the start of symptoms. After examining the most recent cases of rabies in North America, it is obvious that rabies following bat exposure can occur without history of a documented bite. The present case report emphasizes that the general public and medical care providers need better information about the risks associated with exposure to bats

Real-time detection of formaldehyde by a sensor

International audienceA hand-held formaldehyde (HCHO) gas detector has been developed. This fluorescence-based system uses a standard microscope glass slide both as a transducer and a sensor. The detection of gaseous formaldehyde is performed using the well-known Sawicki reaction with Fluoral-P, a reagent present in the nanoporous thin film which allows a selective reaction with formaldehyde. The nanoporous film of hybrid organic-inorganic polymer, prepared via the sol-gel method, is coated on the microscope slide by spin-coating, enabling reproducible coatings of various shapes and thicknesses. Experiments were carried out in the laboratory to calibrate the instrument, with the objective to perform measurements indoor and outdoor. The real-time monitoring allows to detect formaldehyde pollution peaks