Selective proteolytic sensitivity of sulfate-collagen and basement membranes

The relevance of the aldehyde bisulfite toluidine blue reaction and its variants in the submicroscopic carbohydrate research

Carbohydrates are chemical compounds that contain only oxygen, hydrogen and carbon. They are classified by their number of sugar units: monosaccharides (such as glucose and fructose), and disaccharides (such as sucrose and lactose) are simple carbohydrates; oligosaccharides and polysaccharides (such as starch, glycogen and cellulose) are complex carbohydrates. Carbohydrates play a crucial role in diverse biological systems [Hricovín M. Structural aspects of carbohydrates and the relation with their biological properties. Curr Med Chem 2004;11:2565-83]. According to Roseman [Sugars of the cell membrane. In: Weissmann G, Clairborn E, editors. Cell membranes. Biochemistry, Cell Biology, Pathology. New York: H. P. Publ. Co; 1975. p. 55-64], two classes of glycoproteins are described. Free glycoproteins are localised in the surface coat of the membranes and form a thick mobile layer, without any association to the membrane itself. Functionally, however, they are located in a close association with the membrane (e.g. in the duodenal mucosa). The other group consists of the membrane glycoproteins, which are integral to the membranes and are located in the outer layer. The oligosaccharide chains are bound to the N-terminal part of proteins, and are situated in the hydrophilic zone. Glycoproteins have diverse functions. They are important in specific receptor functions, in immunological cell destruction and play a significant role in reactions with lectins, antibodies, as well as in cell association and mutual recognition of the cells. This paper focuses on aspects of a summary of polarisation optical investigations and biological functions of the following three groups of carbohydrates: oligosaccharides, glycoproteins and glycosaminoglycans.

George Romhányi (1905-1991): pioneer in amyloid research and polarization microscopy, on the 100th anniversary of his birth

George Romhányi was an outstanding pathologist, university teacher and a renowned scientist of the 20th century. After studying medicine and pathology, his scientific interest focused on haemochromogenic reactions and submicroscopic structure research. He was among the first to describe the fibrillar-micellar structure of amyloid, as well as the helical-fibrillar structure of elastic fibres. Between 1951 and 1976 Romhányi held the chair of pathology at the University of Pécs. During this time he published numerous topo-optical reactions leading to a renaissance of polarization microscopy. Romhányi's topo-optical reactions possess a high molecular specificity and enabled submicroscopic structural analysis. He and his disciples analysed the biomembrane, collagen fibres, the extracellular matrix of connective tissues, cell walls of bacteria and fungi, the ergastoplasmatic membrane, RNA and DNA. Romhányi's investigation of a range of amyloid depositions was a milestone and led to intensive immuno-biologic research in this area. He firmly held the opinion that polarization microscopy is, along with the electron and fluorescent microscopy, indispensable for solving fundamental questions of molecular biology.

Polarization optical analysis of blood cell membranes

The present study deals with investigations of membrane structure using polarization topo-optical reactions. Polarization microscopy is a special field of biological submicroscopic morphology. It represents a powerful tool well able to reveal the features of organization of biological structures, and the regularity of macromolecules building cells and tissues - properties that cannot directly be studied by other approaches to complex biological systems. Only in "pure" systems can X-ray diffraction, or the analysis of circular dichroism and the dispersion of optical rotability provide data equivalent to those obtained by polarization microscopy in complex systems. One of the main drawbacks of molecular biology is that most information is relevant to isolated, purified particles or macromolecules. Thus, no conclusions can be drawn concerning the original arrangement of molecules. The gap between biochemical-biophysical and morphological approaches to molecular arrangement in complex structures is bridged by the polarization optical technique. As was pointed out in the introduction, polarization microscopy became a routine biological research method following the pioneering work of Romhányi. His enlightening topo-optical reactions (Romhányi 1960, 1963, 1966) were based on the oriented dye binding of the original charge carriers of regularly arranged tissue constituents. The second group of Romhányi's topo-optical reactions comprised procedures such as sulfation (Romhányi et al. 1973, 1974), the aldehyde-bisulfite-toluidine blue (ABT) reaction (Romhányi et al. 1974, 1975), the permanganate-bisulfite-toluidine blue (PBT) reaction (Fischer 1979, 1979a), and the sialic acid-specific reaction (Makovitzky 1980) all of which operate with induced dye-binding groups; i.e. dye-binding moieties on biological macromolecules are produced by specific chemical reactions.

Aldehyde bisulfite-toluidine blue (ABT) staining as a topo-optical reaction for demonstration of linear order of vicinal OH groups in biological structures

The aldehyde-bisulfite-toluidine blue reaction followed by poststaining stabilization with potassium ferricyanide (ABT) is described as a topo-optical, oriented staining reaction of the vicinal OH groups of complex carbohydrates in biological structures such as polysaccharides, glycoproteins and glycolipids. The birefringence as induced by the oriented dye binding as a result of ABT is indicative of linear order of the vicinal OH groups and, in turn, provides information on the ultrastructural pattern of carbohydrate moieties in biological substances, which pattern is often not demonstrable by other ultrastructural methods. The possibilities of this new approach to the ultrastructural analysis of complex carbohydrates with ABT in a great number of biological substances is demonstrated and its practical value in histopathology discussed.