Search PubMed⌕ Search

Biomedical subjects

F Gallyas

Publications and source records attributed to F Gallyas.

At least 55 records · Page 3Linked to original sources
PubMed1986

Metal-catalyzed oxidation renders silver intensification selective. Applications for the histochemistry of diaminobenzidine and neurofibrillary changes.

Physical developers can increase the visibility of end products of certain histochemical reactions, such as oxidative polymerization of diaminobenzidine and selective binding of complex silver iodide ions to Alzheimer's neurofibrillary changes. Unfortunately, this intensification by silver coating is generally superimposed on a nonspecific staining originating from the argyrophil III reaction, which also takes place when tissue sections are treated with physical developers. The present study reveals that the argyrophil III reaction can be suppressed when tissue sections are treated with certain metal ions and hydrogen peroxide before they are transferred to the physical developer. The selective intensification of Alzheimer's neurofibrillary changes requires a pre-treatment with lanthanum nitrate (10 mM/liter) and 3% hydrogen peroxide for 1 hr. The diaminobenzidine reaction can be selectively intensified when physical development is preceded by consecutive treatments with copper sulfate (10 mM/liter, pH 5, 10 min) and hydrogen peroxide (3%, pH 7, 10 min). In peroxidase histochemistry, this high-grade intensification may help to increase specificity and reduce the threshold of detectability in tracing neurons with horseradish peroxidase or in immunohistochemistry when the peroxidase-antiperoxidase method is used.

3,3'-Diaminobenzidine↗
PubMed1985

Oxalate pretreatment and use of a physical developer render the Kossa method selective and sensitive for calcium.

Based on experiments on agarose gels and tissue, a procedure has been developed which greatly improves the sensitivity and the specifity of the Kossa method for demonstrating calcium in tissue. Tissue calcium is immobilized by acetonic oxalic acid, which simultaneously removes the other sorts of anions capable of precipitating silver ions (e.g. phosphate, carbonate). The resulting submicroscopic grains of calcium oxalate are converted first into silver oxalate then into metallic silver by a treatment with silver nitrate followed by an ultra-violet irradiation (Kossa reaction). These submicroscopic metallic silver grains are enlarged up to microscopic visibility by means of physical development, which makes the staining highly sensitive. Co-staining of the argyrophil sites in the tissue is totally suppressed by various tricks, which render the silver staining selective for calcium.

Animals↗
PubMed1982

Improvement of the electron microscopic detection of peroxidase activity by means of the silver intensification of the diaminobenzidine reaction in the rat nervous system.

For the detection of the peroxidase activity at the electron microscopic level, a recently developed post-intensification method is applied, which plates metallic gold onto the end-product of the diaminobenzidine (DAB) reaction. Ultrastructural analysis of rat hypoglossal neurons labeled with horseradish peroxidase (HRP) through axonal transport reveals that the method is highly specific and more sensitive than the classical HRP--DAB--OsO4 sequence. Gold grains of 2--15 nm in diameter are present in the HRP-containing organelles of the neuron, whereas other elements of the brain tissue do not contain metallic gold.

3,3'-Diaminobenzidine↗
PubMed1982

Physico-chemical mechanism of the argyrophil I reaction.

Kinetic experiments have shown that the argyrophil I reaction (the formation of metallic from ionic silver by reducing groups of the tissues) is a catalytic process. Topochemical considerations, and several reaction kinetic observations, suggest that the semi-conductor properties and the favourable chemical structure of certain sites (catalytic points) of the tissue structure play a fundamental role in the catalysis. The electrochemical half processes in the argyrophil I reaction (i.e., the transformation of tissue-bound reducing groups into their oxidized form and the reduction of silver ions into silver atoms) take place separately in space, while the electrons released in the former half reaction are transported by the semi-conduction bands of the tissue to the catalytic points where the metallic silver grains are formed.

Catalysis↗
PubMed1982

Physico-chemical mechanism of the argyrophil III reaction.

Because there are several points of physico-chemical similarity between the argyrophil I reaction (formation of metallic silver grains by reducing groups of the tissue) and the argyrophil III reaction (formation of metallic silver grains by reducing groups existing in a dissolved state) a similarity between their mechanisms is also assumed. The electrochemical half processes of the argyrophil III reaction (i.e. the transformation of tissue-adsorbed reducing molecules into their oxidized form, and the reduction of silver ions to silver atoms) take place separately in space, while the electrons released in the former half reaction are transported by the semiconduction bands of the tissue to the catalytic points where the metallic silver grains are forming.

Catalysis↗
PubMed1982

Suppression of the argyrophil III reaction by mercapto compounds (a prerequisite for the intensification of certain histochemical reactions by physical developers).

The tissue structure catalyse the interaction of silver ions with reducing molecules dissolved in physical developers, producing metallic silver grains bound at the sites of their formation (argyrophil III reaction). This reaction can be considerably slowed by a treatment with thioglycolic acid or certain other mercapto compounds before development. This observation offers a means for intensifying the end-products of certain histochemical reactions through the use of physical developers, without the microscopic image being interfered with or masked by the "unspecific" staining originating from the argyrophil III reaction.

Brain↗
PubMed1982

High-grade intensification of the end-product of the diaminobenzidine reaction for peroxidase histochemistry.

A simple and reliable method is described for the intensification of the end-product of the diaminobenzidine reaction demonstrating peroxidase activity. After completing the diaminobenzidine reaction, the preparations to be intensified are immersed first in thioglycolic acid solution, then in distilled water, and finally in a special physical developer containing silver nitrate.

3,3'-Diaminobenzidine↗
PubMed1981

An argyrophil III method for the demonstration of elastic fibres and membranes.

An esterification with isopropyl alcohol containing 0.2% periodic acid and 2% acetone (at 56 degrees C for 16 hours) followed by a treatment in a special physical developer, similarly, an acetylation with a 3:2 mixture of pyridine and acetic anhydride (at room temperature for 16 hours) followed by the same development, render the elastic fibres and membranes visible. Both pretreatments (esterification and acetylation) serve to make the catalytic points more active in the elastic elements than in the other components of tissue.

Acetylation↗
PubMed1981

An argyrophil III method for the demonstration of smooth muscle cells in light and polarization microscopy.

An esterification with n-butyl alcohol containing 0.5% sulphuric acid (at 56 degrees C, for 16 hours) followed by a treatment in a special physical developer renders smooth muscle cells as well as other contractile elements (striated muscle, cilia, flagella, myoepithel cells) visible in light microscope and birefringent in polarization microscope. A few kinds of non-contractile tissue components without oriented fibrillary structure also stain but do not display birefringence.

Animals↗
PubMed1981

Silver staining of protoplasmic astrocytes by physical development.

The protoplasmic astrocytes adsorb complex Ag(SCN)2- ions from a 40% sodium rhodanide solution containing 1% silver nitrate. The complex is decomposed during a subsequent washing with 5% sodium carbonate, by the excess of rhodanide ions being removed from the sections. Thus, colloid AgSCN grains are made to deposit in the protoplasmic astrocytes. These grains will be reduced first to metallic silver, then enlarged to microscopic dimensions by means of a special physical developer, rendering the protoplasmic astrocytes visible. A pretreatment with 0.01% iodine dissolved in 5% potassium iodide is used to suppress the simultaneous staining of some unwanted tissue elements.

Astrocytes↗
PubMed1981

An argyrophil III method for the demonstration of micro- and oligodendroglia.

Micro- and oligodendroglia, plasma and nucleoli of nerve cells, capillary wall and nuclei of astrocytes become visible when sections of formol fixed human brain are immersed, without any previous treatment, into a physical developer of pH 10.5. The staining is inhibited by the catalytic activity of the tissue elements involved. By means of pretreatments with 1% performic acid and 30% sodium rhodanide dissolved in 0.4% sodium hydroxide, the catalytic activity in the unwanted tissue elements is suppressed, and this results in an elective demonstration of micro- and oligodendroglia. Reducing groups of the tissue or any kind of performed nuclei play no role in this silver staining.

Carbonates↗
PubMed1981

An argyrophil III method for the demonstration of fibrous neuroglia.

The catalytic activity of the fibrous astrocytes in the reaction of silver ions with dissolved reducing molecules is considerably increased by ethylation and a subsequent treatment with NaJO3. As a consequence, in a special physical developer they produce metallic silver at a considerably higher rate than do other tissue elements, making possible their selective demonstration. In freshly fixed materials myelin too is silverized. This can be avoided by means of pretreatments with performic acid and iodine.

Alzheimer Disease↗
PubMed1980

Chemical nature of the first products (nuclei) of the argyrophil staining.

In agreement with LIESEGANG (1911) but in disagreement with VOIGT (1957), PARTRIDGE (1957) and WINKELMANN and SCHMIT (1959), the first product in the majority of the traditional argyrophil methods is submicroscopic grains (nuclei) of metallic silver forming in the impregnating bath at the effect of reducing groups of the tissue (argyrophil I reaction). It is the localization pattern of the metallic silver nuclei that determines the distribution of the silver in the final microscopic image, and not the colloid character of the tissue, as stated by VOIGT (1952) and others. In special cases, colloid grains of certain silver compounds (non-metallic silver nuclei) forming with the contribution of the tissue (argyrophil II reaction) in the impregnating bath constitute the basis of the staining. There are argyrophil methods which consist of pretreatments and a physical development but have no impregnation phase. In one part of them, non-metallic silver nuclei forming with the contribution of the tissue (argyrophil II reaction) in the physical developer, in the other part, certain points of the tissue structure with favourable chemical composition, capable of catalyzing the interaction of silver ions and the reducing component of the physical developer (argyrophil III reaction) serve for the initiation of the staining.

Animals↗
PubMed1980

Determination of the development time for the characterization of the nucleus formation in the argyrophil stainings.

Visual end-point "detection" is proposed for the determination of development time. One of adjacent sections is silverized up to an arbitrary intensity and the others treated in various manners for the investigation of certain processes of silver staining are developed until a given area of them equals in intensity, as "detected" by naked eye, with the same area of the control section. Due to the capacity of the human eye "to detect" identity or divergency accurately in light intensity, the error of development time does not exceed the value of 10%. Whereas, alterations of development time caused by the procedure tested mount up even to 300%.

Astrocytes↗
PubMed1980

Role of the structural elements of the arterial wall in the formation and growth of intracranial saccular aneurysms.

Besides apical medial gaps, lateral and circular medial gaps can be found occasionally at the branching sites of human intracranial arteries, supporting Forbus's idea (1930) of their mechanism of formation and contradicting those put forward by later workers. The large medial gaps situated just distal to the branching sites, considered by Stehbens (1963) to be degenerative in origin, may result from enlargement of congenital multiple apical gaps. Degeneration of the internal elastic layer in the area of medial gaps consists in enlargement and partial fusion of its "physiologic" windows. In contrast to the prevailing opinion, human intracranial arteries do have a well-developed external elastic layer whose density gradually decreases with increasing lengths of the medial gaps. The fundus of a mature aneurysm generally contains no continuous elastic membrane or fiber and relatively little granular elastic material. The equilibrium between partial degeneration and steady reformation of adventitial collagen fibers makes possible the growth of an aneurysm. The thickening of the aneurysmal intima appears to be in causal relationship with the stagnation zones existing in larger aneurysms. In special cases small islets of the arterial media can get into the fundus of an aneurysm, whose spindle-like smooth muscle cells, arranged in a parallel manner, may dissociate themselves from each other and be transformed into spider-like cells.

Cerebral Arteries↗