[Localization of polysaccharides, proteins and lipids in human and pig blood platelets (author's transl)]

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.

Immunocytochemical localization of fibrinogen, platelet factor 4, and beta thromboglobulin in thin frozen sections of human blood platelets

Affinity-purified monospecific antibodies against human fibrinogen and the platelet-specific proteins platelet factor 4 and beta thromboglobulin were used to localize these antigens in thin and ultra-thin frozen sections of mildly fixed, washed human blood platelets. By immunofluorescent double-labeling experiments the distribution of fibrinogen was compared to that of platelet factor 4 and beta thromboglobulin. All three antigens occurred in virtually all platelets and showed and identical, dotlike distribution. For immunoelectron microscopy we used protein A-colloidal gold on ultra-thin frozen sections to visualize the specific reaction indirectly. The staining for platelet factor 4, beta thromboglobulin, and fibrinogen localized exclusively over alpha-granules of washed platelets. Within the granules, platelet factor 4 was localized preferentially in the electron dense, alpha-granule nucleoid, whereas fibrinogen was more predominant in the electron-lucent granule periphery. Beta thromboglobulin localization did not show a preferential intragranular distribution.

Topo-optical reactions of the human blood platelet membrane

The polarization optical analysis of human blood platelets was carried out by means of topo-optical staining reactions. Similar studies have not been performed so far. With this approach we were able to demonstrate the spatially oriented nature of glycoprotein components in the platelet membrane. Using a sialic acid specific topo-optical reaction the sialic acid component of human platelet membrane was selectively demonstrated and the even distribution of sialic acid residues on the membrane surface was also suggested. Polarization optical analysis has shown a membrane-parallel orientation of oligosaccharide chains carrying sialic acids.

A novel approach for enzyme histochemical and autoradiographic studies on single cells

A simple technique that does not involve the use of heat has been developed to fix cells or cell organelles. The cells or organelles are mixed with a bovine serum albumin solution, gelled by the addition of a suitable fixative, and then either embedded or frozen. The gelled mixture contains well preserved cells or organelles that are evenly dispersed, thus eliminating the problems of pellet packing. The technique was excellent for ultrastructural autoradiography where radioactive materials bound to plasma membranes or cytoplasmic nucleotides were being studied. Histochemical tests could be applied to the fixed embedded material. Light and electron microscopy could be done on the same well-mixed sample. Fixed frozen albumin samples cut with ease on a cryostat but there was ice crystal formation.