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Query: UMLS:C0851184 (thinning)
 11,252 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Rhelogical measurements on a dilute suspension of red blood cells (RBCs) are interpreted by means of a microheological model that relates the shear evolution of the apparent viscosity to the intrinsic properties of the suspended particles. It is then possible to quantify the average deformability of a RBC population in terms of a mean value of the membrane shear elastic modulus, Es. Dilute suspensions of erthrocytes exhibit shear-thinning behavior with a constant high shear viscosity. This behavior is identical to the one predicted for a suspension of spherical capsules where the same phenomena of deformation and orientation prevail. A comparison between theoretical and experimental curves yields a mean value of Es, assuming all other cell properties--internal viscosity, geometry--to be otherwise equal. In Dextran, the values of Es for normal RBCs are found to be of order 3.10(-6) N/m. For erythrocytes hardened by heat exposure for 15 minutes at 48 degrees C, the increase in Es reaches 45 percent. This procedure of shear elastic modulus determination is easy to perform and seems to give a good discrimination between normal and altered erythrocytes.
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PMID:Determination of the red blood cell apparent membrane elastic modulus from viscometric measurements. 212 May 13

Human cadaver eyes can be dehydrated by prolonged elevation of intraocular pressure (three to five hours) or by hyperosmotic Dextran over a 20- to 30-minute period. We divided four pairs of donor eyes into two groups (A and B) and dehydrated four corneas by each method. After corneal thinning to 500 to 600 microns, central corneal pachymetry was measured every ten minutes during the rehydration period for one hour, with each cornea pair being moistened at a different rate (every 30 seconds, 1 minute, 2.5 minutes or 5 minutes). The resultant increase in central corneal thickness noted by change in pachymetry (delta P) ranged from 12.4% to 14.7% over one hour between the two groups. delta P did not differ significantly between groups A and B, regardless of the varying rate of balanced salt solution irrigation of the corneas. Thus, it appears that either method of corneal dehydration provides comparable stability of corneal thinning for at least one hour to allow consistent corneal dynamics for experimental refractive surgery.
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PMID:Human cadaver corneal thinning for experimental refractive surgery. 248 49