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Biomedical subjects

F Gallyas

Publications and source records attributed to F Gallyas.

At least 73 records · Page 4Linked to original sources
PubMed1980

Experimental studies of mechanisms involved in methods demonstrating axonal and terminal degeneration.

Factors influencing the consistency and specificity of the staining of neuronal degeneration products were studied in brain sections by varying systematically the composition of solutions used in the steps which are common to the degeneration methods. The formation of nuclei of metallic silver was determined either by physical development of 110Ag, after dissolving reducible silver by acetic acid. In degenerating axons metallic silver nucleic are formed by their own reducing groups in the first (acid) and in the second (alkaline) impregnating bath. The first impregnation turned out to be sufficient to produce complete staining of degenerating axons. The reducing capacity of normal axons and myelin can be suppressed by oxidation or by lowering the pH of the impregnating solution. Degenerating axon terminals are not able to reduce silver ions in either of the impregnating baths. Rather, the metallic silver nuclei initiating their staining are formed in the Nauta reducer by interaction of its reducing agent (formol) with silver ions which had been trapped in the tissue during the impregnation. Thus the nuclei are enlarged to microscopic visibility by a nonstandardized physical developer coming about from the Nauta reducer and the silver ions transferred with the sections. In this reaction catalytic sites in degenerating terminals as well as ammonium ions and the alkali reserve of the tissue play an important role. On the basis of the present results it was possible to stabilize the conditions for staining degenerating axons and degenerating axons terminals in two separate staining procedures detailed in following papers.

Animals↗
PubMed1980

A reliable method for demonstrating axonal degeneration shortly after axotomy.

A method has been elaborated by which degenerating axons can be selectively impregnated with silver. Based on reconsideration of the physicochemical mechanisms of the degeneration methods it takes advantage of physical developers over the chemical ones. The staining procedure is applied to frozen sections of brains fixed with formol. It consists of 6 steps: (1) pretreatment with alkaline hydroxylamine, (2) washing in acetic acid, (3) impregnation in silver nitrate in the presence of ferric ions, (4) washing in citric acid, (5) physical development, and (6) washing in acetic acid. By electron microscopy silver precipitates by this method are almost entirely restricted to the cytoplasm of dense, degenerating axons, sparing mitochondria and myelin sheaths. No special expertise is required to achieve reproducible results. Large numbers of sections treated simultaneously, and large sections, can be stained uniformly. Light microscopic criteria are described which help diagnose the source of possible failures. Low background staining allows dark field illumination and television image analysis to be applied. The method works at survival times of only 3 to 5 days after axotomy. Hence, degenerating axons and axon terminals can be stained in alternating sections from the same brain using this method and another being described separately, which, using different conditions, demonstrates degenerating axon terminals.

Animals↗
PubMed1980

A reliable and sensitive method to localize terminal degeneration and lysosomes in the central nervous system.

After reconsidering the physicochemical mechanisms involved in the so-called degeneration methods for the demonstration of axons and nerve terminals, the method of Eager was fundamentally modified in order to stabilize the staining process. This resulted in a simple and reliable method which stains degenerating terminals and lysosomes with a high degree of selectivity and sensitivity. Frozen sections 30 to 50 micrometers thick are prepared from material fixed with formaldehyde by cardiac perfusion. The staining procedure consists of 5 steps: 1) alkaline pretreatment (pH 13), 2) silver impregnation, 3) washing, 4) development at pH 5.0-5.5 monitored by an indicator, and 5) washing in acetic acid. Possible faults can be easily detected by their specific effects on the staining results. Primary submicroscopic silver precipitates are localized selectively in the osmiophilic parts of lysosomes and those degenerating presynaptic elements that are surrounded by glial processes. In degenerating axons, precipitates originating from mitochondria can usually be distinguished from terminal degeneration by their different size, shape, or characteristic arrangement. Nonspecific staining is restricted to glial fibrils, erythrocytes, and single cell nuclei. Dark field illumination can be applied routinely and television image analysis can be used for quantitative evaluation because of low background staining.

Animals↗
PubMed1980

The study of bone tissue with new argyrophilic techniques.

Fractured and necrotic bones were examined by new silver impregnation techniques based on the catalytic activity of the bone. The new methods proved to be useful in differentiating between bone tissues of various ages and maturity and between living and necrotic bones.

Alcohols↗
PubMed1980

[Methods of the selective demonstration of various structural elements of the vascular wall].

Selective topo-optical and impregnation technique for the demonstration of acid mucopolysaccharides, neutral polysaccharides, collagen, elastic fibres and membranes, smooth muscle cell i.e. structural elements of the vessel wall are described. These techniques are simple and reliable and may be used for the every-day pathohistological diagnostics. Their parallel application provides further possibilities for the study of the structure and various pathological alterations of the vessel wall. It should be stressed, that on the basis of the analysis of optical effects--birefringence, dichroism, metachromasia--these techniques provide opportunity to detect early structural lesions, which by the application of conventional techniques can not be detected.

Arteries↗
PubMed1979

Simultaneous determination of the amounts of metallic and "reducible" silver in histologic specimens.

Acids and weak complexing agents (pK less than 8) are not able to remove, without leaving a residue, silver bound to biological tissues by ionic or complex bonds ("reducible" silver), whereas, strong complexing agents (pK greater than 8) can also partially or completely dissolve metallic silver formed under the influence of reducing groups in the tissue. For this reason, the chemical nature of the silver contained in tissue sections, be it metallic or reducible, must not be determined on the basis of solubility tests; moreover, the amount of neither of the two above fractions can be determined by removing the other with any kind of washing. Using radioactive impregnating baths, radioactive silver bound to the tissue as reducible silver can be replaced in a quantitative manner with inactive silver ions by means of a one-hour incubation in 1% inactive silver nitrate dissolved in 10% acetic acid, but the radioactive silver existing in reduced (atomic) state will be left unaffected. Consequently, radioactivity remaining in the tissue after the above treatment represents metallic silver. The amount of reducible silver can be calculated by subtracting that of the metallic silver from the total silver content of the sections.

Histocytochemistry↗
PubMed1979

Kinetics of formation of metallic silver and binding of silver ions by tissue components.

The effect of time on the formation of metallic silver by tissue reducing groups follows a curve which can be divided into three main parts. In the first, which may last for several hours, the reaction is very slow, and only an undetectably small amount of metallic silver is produced. In the second period the speed of the reaction first increases in a progressive manner and then begins to decrease gradually; during the third period the speed approaches zero asymptotically. Binding of the silver ions by the tissue commences initially at its fastest rate; the level then decreases steadily to zero within about a quarter of an hour. There is no direct relationship between the amount of silver ion bound to the tissue and the formation of metallic silver. The latter cannot take place by way of direct (non-catalysed) reaction. The following mechanism is proposed for the process: Transfer of electrons from the reducing molecules to the silver ions is mediated at first by certain tissue sites (catalytic points) and then also by the steadily increasing total surface area of the metallic silver grains (autocatalysis). On the basis of this mechanism, several anomalies of both the argentaffin and argyrophil reactions are explained.

Histocytochemistry↗
PubMed1979

Factors affecting the formation of metallic silver and the binding of silver ions by tissue components.

The rate of formation of metallic silver has a maximum when plotted as a function of pH. The site of this maximum on a pH scale differs noticeably for various tissue elements. By contrast, the amount of silver ions bound to the tissue is a monotonously increasing function of the pH. A temperature rise decreases the length of the induction period and increases the gradient of the ascending section of the kinetic curve representing the formation of metallic silver. It also increases the maximum amount of silver ions bound to the tissue. An increase in the concentration (activity) of the silver ions in the impregnating bath has the same effect. Chemical composition and concentration of the complexing agent, as well as "special" ions in the impregnating bath to which earlier some definitive role has been attributed in the silver staining methods, proved to be ineffective when both pH and activity of silver ions were kept constant. Illumination of the reaction was also ineffective. The kinetic curves obtained in nonaqueous but polar media (e.g., acetone) exhibited the same qualitative characteristics as those obtained in aqueous solutions. No reaction between silver ions and tissue was observed in apolar solvents.

Histocytochemistry↗
PubMed1979

Silver staining of myelin by means of physical development.

For staining myelin with silver a physical development technique has been devised that can render visible the thinnest fibers in various animal species, including fishes and reptiles, even in the early phase of myelination and may be applied to both frozen and embedded materials. Its principle is as follows: Myelin can form and bind colloidal silver particles in a 0.1% ammoniacal silver nitrate solution of pH 7.5. The production of metallic silver by other tissue elements is suppressed by the sections pretreated with a 2:1 mixture of pyridine and acetic anhydride for 30 min. The colloidal silver particles bound in the myelin are enlarged to microscopic dimensions by a special physical developer.

Animals↗
PubMed1979

Light insensitive physical developers.

Within the pH range 2.5-6.5 tungstic acid (an isopolyacid) prevents the reduction of silver ions by ascorbic or hydroquinone more effectively than either gum acacia or other protective colloids. The colloid state of tungstic acid can be stabilized with nonionic detergents, especially with Triton X-100. For buffering the system a mixture of acetic acid and sodium acetate is optimal. Physical developers constituted on the basis of these observations are, in contrast to those commonly used in histology, light insensitive, and remain clear for about 30 min at room temperature, 2-5 times as long as the time required for development.

Buffers↗
PubMed1979

An improved silver stain for developing nervous tissue.

A reduced silver technique using physical development to stain embryonic nervous tissue is described. Brains are fixed in Bodian's fixative. Paraffin sections are pretreated with 1% chromic acid or 5% formol. They are impregnated with 0.01% silver nitrate dissolved in 0.1 M boric acid/sodium tetraborate buffer of pH 8 or with silver proteinate. Finally they are developed in a special physical developer which contains 0.1% silver nitrate, 0.01-0.1% formol as reducing agent, 2.5% sodium carbonate to buffer the solution at pH 10.3, 0.1% ammonium nitrate to prevent precipitation of silver hydroxide, and 5% tungstosilicic acid as a protective colloid. The development takes several minutes in this solution, thus the intensity of staining can be controlled easily. The method yields uniform, complete and reproducible staining of axons at all developmental stages of the nervous tissue and is easy to handle.

Animals↗
PubMed1977

[Selective and high-contrast staining in nervous tissue (author's transl)].

Using silver as an impregnating medium and controlling the staining process by physical development, a specific and reliable staining of high contrast can be achieved. These properties represent important prerequisites for automatic and quantitative television image analysis. Specificity depends on appropriate pretreatment. Television image analysis cannot only be used for object analysis, but also to quantify reliability and dependency of contrast on developmental conditions, as demonstrated for stained myelin.

Animals↗
PubMed1976

Lactate production during fructose infusion with or without amino acids.

Lactate production from the liver during fructose infusion was decreased when an amino acid infusion was given simultaneously. The most pronounced decrease was observed when the amino acid infusion was started before the simultaneous administration of fructose and amino acids. The explanation of the phenomenon is thought to be a stimulation of gluconeogenesis by amino acids.

Amino Acids↗
PubMed1975

Acute renal failure caused by leptospirosis.

Three patients with severe leptospirosis leading to anuria and treated with haemodialysis are reported. One patient died. The pathomechanism and the underlying pathological and histological changes of the renal failure are discussed. It is stressed that the clinical diagnosis of leptospirosis is often difficult, as other infectious diseases,first of all infectious hepatitis, frequently present the same symptoms.

Acute Kidney Injury↗
PubMed1975

Intensification of cobaltous sulphide precipitate in frog nervous tissue.

Dorsal and ventral roots of the frog's spinal cord were filled with cobaltous chloride through axonal transport. Following incubation in different buffers saturated with H2S, the resulting CoS was intensified with two kinds of physical developers, the one containing gum arabic, the other tungsto-silicic acid as protective colloid. Optimum circumstances for CoS formation were found at high pH values in model experiments. NaOH and CuSO4 pretreatments of tissues enhanced the intensification power of the physical developer containing tungsto-silicic acid. The structural integrity of tissues was best preserved when phosphate buffers saturated with H2S were employed to precipitate cobalt in histological specimens. Of the two developers the one containing gum arabic gave a finer staining of neural elements, but its intensification effect was somewhat capricious. Histological results suggested that within the range of cobalt transport (10-20 mm), neural elements filled with cobalt were quantitatively and selectively shown. At the present state of experiments neural elements with a process to the periphery are only accessible to staining with this technique.

Animals↗