This study was designed to define how hyaluronan (HA) is bound in lung tissue. Aliquots of lyophilized hamster lungs were extracted with 0.5 M NaCl (associative conditions) or 4 M guanidine . HCL (Gu . HCl) (dissociative conditions) or with water. Aliquots were also digested with Pronase in phosphate-buffered saline (PBS) or in dilute Tris buffer. The nanogram amounts of solubilized HA were quantified by an inhibition assay based on the specificity of binding of HA to biotinylated HA-binding protein (B-HABP) rather than radioactive HA-binding protein. Lung HA was readily soluble. More than 80% of it was solubilized by one extraction with either 0.5 M NaCl or 4 M guanidine . HCl. Almost half of it was solubilized by two brief (15-min) water washes. After three extractions under associative conditions only 5% of the total HA remained insoluble and could exist in structural proteoglycan aggregates. However, HA is present in lung in more than one situation, as was discerned in Pronase digestion experiments. Digestion of lung tissue with Pronase solubilized total lung HA. In PBS all the HA was detected, but in dilute Tris buffer 52% of the HA solubilized was not available for combination with the B-HABP and was presumed to be bound to another lung component. Overall, the data suggest that lung HA is free to engage in water transport and to provide a protective coating for elastin and collagen fibers.
The emission and excitation spectra of quinoline and 2,3-dichloroquinoxaline embedded in a calcinated (600 °C) porous Vycor glass and dissolved in fluid solutions were recorded at various temperatures. The spectral characteristics and phosphorescence lifetimes of adsorbates were observed to be identical with those in 0.5 N H2S04 solutions, indicating that H+ is transferred from the surface to the N-heterocyclics. The strong surface-adsorbate interaction is further revealed by the dynamic study of adsorbates at 77 and 4.2 K.
Emission spectra and lifetimes at 77 K are reported for samples prepared by adsorbing benzo[c]cinnoline (9,10-diazaphenanthrene; 9,10-dp) in sintered Vycor glass. For Vycor supports calcinated at 300, 400, 600, and 900 °C, the embedded species are identified as hydrogen-bonded 9,10-dp, protonated 9,10-dp, protonated dihydro-9,10-dp, and protonated carbazole, respectively.The transformations are explained as resulting from an increase in the surface Bronsted acidity of Vycor glass upon sintering and are surface-induced in nature. For sintering temperatures below 400 °C the emission is bright and occurs uniformly from the entire sample. However, the emission intensity decreases rapidly as the sintering temperature is raised from 600 to 900 °C. This is interpreted as due to a shrinkage of the porous glass at higher calcinating temperatures. These observations suggest that the emissive adsorbate is really embedded inside the pores of the Vycor glass.
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