Single-cell adhesivity distribution of glycocalyx digested cancer cells from high spatial resolution label-free biosensor measurements.

The glycocalyx is a cell surface sugar layer of most cell types that greatly influences the interaction of cells with their environment. Its components are glycolipids, glycoproteins, and oligosaccharides. Interestingly, cancer cells have a thicker glycocalyx layer compared to healthy cells, but to date, there has been no consensus in the literature on the exact role of cell surface polysaccharides and their derivatives in cellular adhesion and signaling. In our previous work we discovered that specific glycocalyx components of cancer cells regulate the kinetics and strength of adhesion on RGD (arginine-glycine-aspartic acid) peptide-coated surfaces [1]. Depending on the employed enzyme concentration digesting specific components both adhesion strengthening and weakening could be observed by monitoring the averaged behavior of thousands of cells. The enzyme chondroitinase ABC (ChrABC) was used to digest the chondroitin-4-sulfate, chondroitin-6-sulfate, and dermatan sulfate components in the glycocalyx of cancer cells. In the present work, a high spatial resolution label-free optical biosensor was employed to monitor the adhesivity of cancer cells both at the single-cell and population level. Population-level distributions of single-cell adhesivity were first recorded and analyzed when ChrABC was added to the adhering cells. At relatively low and high ChrABC concentrations subpopulations with remarkably large and weak adhesivity were identified. The changes in the adhesivity distribution due to the enzyme treatment were analyzed and the subpopulations most affected by the enzyme treatment were highlighted. The presented results open up new directions in glycocalyx related cell adhesion research and in the development of more meaningful targeted cancer treatments affecting adhesion.

Chemical action of influenza virus on the red blood cell membrane. II. Action on membrane lipids and amino acids.

Haemagglutination by influenza virus strains PR8 and Lee as well as treatment of red blood cells by periodate produced numerous and manifold changes in the lipids and the amino acid composition of the erythrocytes. The changes induced by the influenza strains differed from each other and from those induced by periodate. Alterations in the membrane lipids observed after haemagglutination by heat treated strain PR8 and by its native form were identical.

Chemical action of influenza virus on the red blood cell membrane. I. Action on membrane neuraminic acids.

The chemical action of influenza virus strains PR8 and Lee and of periodate on the neuraminic acid containing lipids of human red blood cells has been investigated by thin layer chromatography. The results showed that haemagglutination by the two strains as well as periodate treatment induced manifold and profound chemical alterations in the neuraminic acid-containing lipids. The changes produced by strains PR8 and Lee differed from each other and from those caused by periodate. Alterations in the neuraminic acid-containing lipids induced by heated strain PR8 were identical with those obtained after haemagglutination by the native virus, indicating that virus neuraminidase is not inactivated by heat. Thus, differences in the haemagglutinating ability between native and heated virus are not due to enzyme inactivation.