Using a laser diffraction technique, we have studied factors that influence the deformability of erythrocytes. Variations in suspending medium osmolality and applied shear stress were employed to isolate the individual contributions to whole cell deformability of internal viscosity, surface area-to-volume ratio, and viscoelastic properties of the membrane. An experimental system was devised in which normal cells were modified in vitro to induce specific alterations in each factor. Measurements of deformability as a function of medium osmolality showed characteristic behavior of the modified cells. Reduced surface area-to-volume ratio was detected by an exaggeration of the normal decrease in deformability as medium osmolality was decreased. In contrast, increased internal viscosity was detected by an increase in deformability as osmolality was decreased. Finally, decreased membrane flexibility was detected by reduced deformation at low shear stress. These methods of analysis were applied to cells from patients with hereditary spherocytosis, hereditary pyropoikilocytosis, and hemoglobin CC disease to define the basis of reduced deformability. Hereditary spherocytes showed the combined effects of reduced surface area and increased internal viscosity. Hereditary pyropoikilocytes revealed the effects of severely reduced surface area-to-volume ratio. Hemoglobin CC cells showed only the effects of high internal viscosity. An increase in the membrane shear modulus (decreased membrane deformability) was not evident in these disorders.
N Mohandas, M R Clark, M S Jacobs, S B Shohet
Usage data is cumulative from May 2019 through May 2020.
Usage information is collected from two different sources: this site (JCI) and Pubmed Central (PMC). JCI information (compiled daily) shows human readership based on methods we employ to screen out robotic usage. PMC information (aggregated monthly) is also similarly screened of robotic usage.
Various methods are used to distinguish robotic usage. For example, Google automatically scans articles to add to its search index and identifies itself as robotic; other services might not clearly identify themselves as robotic, or they are new or unknown as robotic. Because this activity can be misinterpreted as human readership, data may be re-processed periodically to reflect an improved understanding of robotic activity. Because of these factors, readers should consider usage information illustrative but subject to change.