PubMed · 14318744
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A DIBENEDETTO. 1965. SUBPHRENIC ABSCESS.. https://pubmed.ncbi.nlm.nih.gov/14318744/
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The quantity and composition of airway surface liquid (ASL) are essential to host defense. To date, attempts to harvest ASL and measure its composition have yielded conflicting results. We investigated the physical principles underlying two techniques that were proposed for harvesting ASL: filter paper pledgets and polyethylene catheters. We compared the force and pressure generation and the kinematics of capillarity-induced fluid uptake with both techniques. Both have significant limitations for harvesting ASL, generating physiologically significant pressures (filter paper, 60.4 Pa; polyethylene, 14.3 Pa) that could potentially compromise epithelial integrity. Furthermore, filter paper generates a force 85-fold higher than the polyethylene catheter, which is associated with a very high rate of uptake of liquid and a large total amount of liquid relative to ASL thickness. While the PE catheter harvests liquid more gently, it is only effective when ASL surface tension is below 31 mN/m. These limitations likely account for some of the variability in reported ASL composition, and highlight the need for improved methods for harvesting ASL.
Paired helical filaments (PHF) is an aberrant structure present in the brain of Alzheimer's disease patients which has been correlated with their degree of dementia. In order to determine the structure of PHF, several studies have been performed using atomic force microscopy (AFM). However, those studies have the limitation that they have not been done in solution and the sample could be far from the real physiological conditions. In this work we present an AFM analysis of PHF in liquid environment and we compare that analysis with that performed in dry conditions. PHF imaging in liquid was only possible by using jumping mode AFM as the imaging technique. Jumping mode AFM images of PHF in solution show first, a notable increase in the absolute values of the height of the filament, and second, a smaller ratio between the height measured at the upper and at the lower part of the PHF. Direct comparison of the experimental data with structural models has been performed. From this we conclude that the PHF structure is compatible with two coupled ribbons with an overall height of 20 nm and a width of 10 nm.
Hydrolysis and polycondensation of triethoxysilane end-capped Poly (tetramethylene oxide) (Si-PTMO), tetraethoxysilane (TEOS), tetraisopropyltitanate (TiPT) and calcium nitrate (Ca(NO(3))(2)) gave transparent monolithics of PTMO-modified CaO-SiO(2)-TiO(2) hybrids. The samples with (TiPT)/(TEOS+TiPT) molar ratios from 0 to 0.20 under constant ratio of (Si-PTMO)/(TEOS+TiPT) of 2/3 in weight were prepared. It was found that the incorporation of TiO(2) component into a PTMO-CaO-SiO(2) hybrid results in an increase in the apatite-forming ability in a simulated body fluid: the hybrids with (TiPT)/(TEOS+TiPT) of 0.10 and 0.20 in mol formed an apatite on their surfaces within only 0.5 day. It seemed that, within the range of compositions studied, the TiO(2) content little affects the overall mechanical properties: Young's modulus were 52-55MPa, tensile strength, 7-9MPa, and strain at failure, about 30%. Thus, the organic-inorganic hybrids exhibiting both fairly high apatite-forming ability and high capability for deformation were obtained. These hybrid materials may be useful as new kind of bioactive bone-repairing materials.