Pathological mucus and impaired mucus clearance in cystic fibrosis patients result from increased concentration, not altered pH

Cystic fibrosis (CF) is a recessive genetic disease that is characterised by airway mucus plugging and reduced mucus clearance. There are currently alternative hypotheses that attempt to describe the abnormally viscous and elastic mucus that is a hallmark of CF airways disease, including: 1) loss of CF transmembrane regulator (CFTR)-dependent airway surface volume (water) secretion, producing mucus hyperconcentration-dependent increased viscosity, and 2) impaired bicarbonate secretion by CFTR, producing acidification of airway surfaces and increased mucus viscosity. A series of experiments was conducted to determine the contributions of mucus concentration versus pH to the rheological properties of airway mucus across length scales from the nanoscopic to macroscopic. For length scales greater than the nanoscopic, i.e. those relevant to mucociliary clearance, the effect of mucus concentration dominated over the effect of airway acidification. Mucus hydration and chemical reduction of disulfide bonds that connect mucin monomers are more promising therapeutic approaches than alkalisation

A WATER-COOLED, COMPENSATED SOLENOID FOR HIGH GRADIENT MAGNETIC FILTRATION TESTS

Un solénoïde compensé refroidi à l'eau a été étudié et construit dans le but de produire un champ magnétique uniforme pour une expérience de filtration magnétique à haut gradient. Le bobinage utilise un conducteur creux en cuivre de section carrée 6,35 x 6,35 mm2. Le solénoïde a un alésage de 113 mm et une longueur de 317 mm. Les composantes axiale et radiale du champ magnétique ont été mesurées à l'aide de sondes de Hall respectivement axiale et transverse. La distribution du champ axial montre une bonne homogénéité, se traduisant par une variation du champ sur l'axe de seulement 1,6 % sur une longueur de 150 mm dans la région centrale. Les champs radiaux sont très faibles dans cette région.A water-cooled, compensated solenoid was designed and constructed to produce a uniform magnetic field for an HGMF investigation. Coils were wound from 6.35 mm square, hollow copper tubes. The solenoid has a 113 mm bore and is 317 mm long. Axial and radial magnetic fields were determined with an axial and a transverse Hall effect field probes respectively. The axial field distribution of the compensated solenoid shows good homogeneity, giving an on-axis field variation of only 1.6% over a 150 mm length of the central region. Radial fields are very weak in this region

From cystic duct to static mixer: A serendipitous journey via flow visualization

The cystic duct is a very complicated conduit that connects the gallbladder to the common bile duct. The geometry of the of the cystic duct and its functions, in particular the valves of Heister, in the flow of bile into and out of the gallbladder have always been a subject of speculation. It has been suggested variously that their function is to: impede the flow of bile into the gallbladder, prevent the outflow of bile from the gallbladder, or prevent the collapse of cystic duct. Presented in this paper is the results of a novel experiment to assess the role of the valves of Heister during both the filling and the emptying phases of the gallbladder. The results suggest that the existence of these valves helps both the filling and the emptying of the gallbladder by providing structural support and preventing the duct from total collapse. A surge of pressure upstream of the cystic duct is observed prior to the opening of the cystic duct which is consistent with previous in-vivo biological observation