Biomedical subjects

G Danscher

Publications and source records attributed to G Danscher.

At least 127 records · Page 7Linked to original sources

PubMed1985

Ultrastructural autometallography: a method for silver amplification of catalytic metals.

The autometallographic technique involves application of a silver bromide-containing emulsion on the surface of ultrathin sections placed on grids that are subsequently exposed to a photographic developer. In tissue sections from animals treated intravitally with gold, silver, or mercury compounds, accumulations of the metals are visualized by autometallography and can be used for quantitative studies. After amplification, sections can be stained with lead citrate and uranyl acetate. Using autometallography, particles of colloidal gold dispersed in a film of gelatin showed a time-dependent growth and were gradually amplified up to 3.5-fold after 15 min of development. Hence the method may prove useful tracing colloidal gold particles in sections with low particle density, and be a powerful tool for revealing metals in biological tissues.

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PubMed1985

Mouse peritoneal cells exposed to sodium aurothiomalate in vivo.

The localization of gold in normal, stimulated and activated mouse peritoneal cells exposed in vivo to sodium aurothiomalate was examined by a new histochemical technique based on physical development. Activated macrophages from mice infected with herpes simplex virus type II showed the greatest amount of gold localized within lysosomes. Mast cells contained gold in their granules. Polymorphonuclear leucocytes and lymphocytes, on the other hand, were devoid of gold. Pinocytosis is discussed as the mechanism by which gold is taken up into the cells.

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PubMed1984

The Timm-stained hippocampus of the European hedgehog: a basal mammalian form.

A quantitative and qualitative description has been made of the components of the Timm-stained hippocampus of the European hedgehog. While the laminar organization and the relative size of the major subdivisions of the hippocampus (i.e., area dentata, Ammon's horn, and subiculum) are similar to those of the albino laboratory rat, the relative proportions and the staining characteristics of some of the components of the subdivisions are different. The differences are particularly evident in Ammon's horn where regions are poorly differentiated along the dentatosubicular axis and the mossy fiber zone is relatively extensive. The description characterizes a hippocampal form that can be used as a basal reference in comparative studies of the mammalian hippocampus.

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PubMed1984

Energy dispersive X-ray analysis of tissue gold after silver amplification by physical development.

Rats were treated intraperitoneally with the gold-containing compounds sodium aurothiomalate (Myocrisin), sodium aurothiosulfate (Sanocrysin), and aurothioglucose. Using stem energy dispersive X-ray analysis, gold and silver were shown to be located at the same point in lysosomes of proximal tubular cells of the kidney, in hepatocytes and in macrophages of lymph glands, spleen and liver. This result indicates that, after exposure to ultraviolet radiation, chemically bound tissue gold is transformed to metallic gold that subsequently can catalyze the reduction of silver ions to silver when subjected to physical development, i.e. exposed to a photographic developer containing silver ions in addition to the reducing molecules.

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PubMed1984

Autometallography. A new technique for light and electron microscopic visualization of metals in biological tissues (gold, silver, metal sulphides and metal selenides).

The autometallographic procedure represents a new technique that can substitute for the normal methods of physical development (PD). The physical developer (a solution of reducing substance, silver salt and protection colloid) is replaced by a photographic emulsion and chemical developer. Accumulations of gold, silver, metal sulphides and metal selenides can be amplified by the present technique. Tissue sections placed on glass slides are covered by a silver bromide containing emulsion, dried and exposed to a chemical developer. After development the emulsion is either removed or cleared and the sections are counterstained and embedded. The autometallographic procedure can also be applied to ultrathin sections.

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PubMed1984

Ultrastructural localization of gold in macrophages and mast cells exposed to aurothioglucose.

The ultrastructural localization of gold in resting, stimulated, and activated mouse peritoneal cells exposed in vivo and in vitro to aurothioglucose was examined by a photochemical technique. Activated macrophages from herpes simplex virus type 2 infected mice showed the heaviest accumulation of gold, located in phagolysosomes. Gold was also visualized in granules of mast cells and in nuclei of disintegrated cells. No gold was found in polymorphonuclear leucocytes and in lymphocytes. The mechanism by which gold is taken up into the cells is discussed.

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PubMed1984

Hypoactivity in silver exposed mice.

The functional implications of the presence of silver in the central nervous system are unknown. Since silver is present in the environment and since systemic silver poisoning leads to intraneuronal accumulations of the metal we have evaluated the possible effects of silver on the open field behaviour of mice. Argyric mice have been compared with controls in three experiments, one including long term administration of 0.015% silver nitrate in the drinking water and two in which the reactions of male and female mice to shock doses of silver lactate have been studied. In all experiments the silver treated mice were hypoactive. We suggest that this hypoactivity is due to an influence of silver upon the functional status of the CNS.

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PubMed1983

Localization of exogenous silver in brain and spinal cord of silver exposed rats.

Exogenous silver in brain and spinal cord sections from rats treated with Protargol, silver lactate or silver nitrate was visualized by physical development. The silver penetrated the blood-brain barrier and accumulated in neurones and glia. The distribution of silver in the CNS was heterogeneous. Even with low doses and short survival periods, silver was found to accumulate in large motoneurones in the brain stem and spinal cord and neurones in the cerebellar nuclei. Silver was only found in di- and telencephalic structures after extensive exposure. Silver distribution following oral silver lactate and silver nitrate treatment differed in that silver nitrate resulted in a relatively high content of silver in glia whereas deposition occurred preferentially in neurones following silver lactate treatment. Electron-microscopical studies showed that silver was located intracellularly in the lysosomes and extracellularly in basement membranes and elastic fibres of the vessels.

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PubMed1983

Neuronal accumulation of silver in brains of progeny from argyric rats.

Using a photochemical method silver was demonstrated in the brains of 1-, 14-, and 45-day-old rats which had been exposed to silver on gestational days 18 and 19. In the brain tissue of new-born rats, silver was found in the lysosomes of neurons and astroglia. Minor changes in the anatomic distribution of silver were observed between days 1 and 45. The pattern seen at day 45 was identical to that observed in silver-exposed adults. At day 1, the choroid plexus and meninges were heavily loaded with silver both intra- and extracellularly. In particular, macrophage-like cells of the meningeal spaces contained large amounts of silver. In these structures, the silver had virtually disappeared by day 45. Silver was always seen in basement membranes of the cerebral vessels.

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PubMed1983

Transplacental transport of gold in rats exposed to sodium aurothiomalate.

The ultrastructural localization of gold in yolk sacs and fetuses from rats exposed to sodium aurothiomalate (Myocrisin, 25 mg/kg intraperitoneally) was examined by a photochemical technique. Gold was found in epithelial cells of the yolk sac and in hepatocytes of the fetuses. Ultrastructurally, gold was located in lysosome-like bodies. Gold was not detected in the kidney or the central nervous system of the fetuses. Maternal liver and kidney were included as controls for efficacy of gold treatment.

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PubMed1983

Light microscopic visualization of colloidal gold on resin-embedded tissue.

RNase labeled with colloidal gold was used as a model for the present technique evolved for the light microscopic localization of gold-labeled substances in semithin resin-embedded sections. Tissue sections placed on glass slides were treated with the gold-enzyme complex and subsequently exposed to a photographic developed containing silver lactate. During the development gold particles are encapsulated in growing shells of metallic silver and gradually made visible in the light microscope. The amplification method can be applied to paraffin-embedded and frozen sections as well. This technique may prove useful as a supplement to studies utilizing colloidal gold or silver as markers normally used at the electron microscopic level.

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PubMed1983

A silver method for counterstaining plastic embedded tissue.

This report presents a method which can be used for counterstaining semithin sections of plastic embedded tissue. The sections are treated with a solution of silver lactate, followed by physical development. During the silver lactate treatment, silver ions are bound by various tissue components as metallic silver or silver sulfide. During physical development catalytic reduction of silver ions to metallic silver takes place where silver has been bound in the tissue, enlarging the silver deposits to microscopically visible dimensions. The amplified silver deposits give high contrast staining in yellow, brown and black suitable for both color and monochrome photography. The localization of the silver deposits is highly specific and may reflect several independent chemical processes. Examples in several tissues are shown.

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PubMed1982

Hippocampal mossy fibers in the regio superior of the European hedgehog.

The hippocampal mossy fiber zone of the European hedgehog has been studied at the light and electron microscopic levels. In contrast to the organization of this zone in other mammals, the mossy fiber zone of the hedgehog is not confined to the region of Ammon's horn that is characterized by large pyramidal cells (i.e. regio inferior) but extends into the region that contains small pyramidal cells (i.e. regio superior). The terminals, throughout the relatively extensive mossy fiber zone of the hedgehog, have the large multivesicular, multicontact morphology that characterizes the mossy fiber terminals observed in other species and can be demonstrated to be the axon terminals of granule cells located in the fascia dentata. In view of the primitive organization of the forebrain of the European hedgehog, which is believed to be representative of that of the first mammals, the boundaries of the mossy fiber zone of these animals suggest that the mossy fibers extended over a larger part of Ammon's horn during the first phases of mammalian evolution and became restricted to the regio inferior during the early stages of mammalian evolution.

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PubMed1982

Exogenous selenium in the brain. A histochemical technique for light and electron microscopical localization of catalytic selenium bonds.

Transcardial perfusion or intraperitoneal injections with sodium selenite result in the creation of selenium bonds that can be visualized by physical development. The present paper describes how these catalytic bonds are made visible in the tissues by surrounding them with shells of metallic silver. Based on experiments with chelating agents, the possibility that selenium-metal bonds are the catalysts is discussed. In the brain, the selenium pattern is delicate and highly laminated, the grains of silver being orderly arranged corresponding with the neuropil morphology. The precipitate is most densely packed in cortical regions. The difference in staining intensity seen in different regions of the CNS reflects the density of selenium reactive terminals. The visualized selenium bonds are predominantly located within boutons, and examination in the electron microscope reveals accumulation in the presynaptic regions. In a few places precipitates can also be found in axons, but have not been observed in perikarya or dendrites. The only non-neuronal locations of selenium were sparsely scattered, astrocyte-like neuroglia, predominantly found in the cerebellum and the hypothalamus; infrequently a few blood vessels were also stained. Sections from kidney and liver are presented as examples of localizations outside the CNS of exogenous selenium.

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PubMed1981

Light and electron microscopic localization of silver in biological tissue.

A method is described that visualizes trace amounts of silver in frozen, paraffin and epon sections from biological tissue. After exposure to light, which ensures reduction of silver ions that are not bound to sulphide, histological sections from animals treated with silver compounds are exposed to a photographic developer containing silver ions. Tissue silver acts as a catalyst for the hydroquinone reduction of silver ions to metallic silver which then accumulates at the site of the trace deposit. Light and electron micrographs showing silver in different organs from albino rats treated with silver lactate are presented. Localization of silver in motor neurons of the spinal gray matter and pons indicates a transport of silver over the blood-brain barrier. Silver precipitates in fetal liver suggest that silver ions can penetrate the placental barrier.

Animals↗

PubMed1981

Histochemical demonstration of heavy metals. A revised version of the sulphide silver method suitable for both light and electronmicroscopy.

The three steps of the sulphide silver method have been examined: 1) Transformation of metals to metal sulphides; 2) Fixation and embedding or freezing of the tissue for sectioning; and 3) Deposition of metallic silver on the metal sulphides in a physical developer. Based on the results, a revised method is described and discussed. It is particularly important 1) To maintain a sufficient but low concentration of sulphide ions during the perfusion; 2) To avoid using oxidating or acid fixatives; 3) To ensure low temperatures while embedding in paraffin or during polymerization of Epon; and 4) to use a slow-acting physical developer. Examples of the metal sulphide pattern from various tissues are presented.

Animals↗

PubMed1981

Localization of gold in biological tissue. A photochemical method for light and electronmicroscopy.

A detailed description is given of a method by which gold can be visualized in frozen, paraffin and Epon sections. Histological sections from animals treated with gold compounds are exposed to UV-light from 30 min to several hours. The reduced, metallic gold is then visualized by means of a photographic developer containing silver lactate. Light- and electronmicroscope photographs showing gold in different organs from rats and mice treated with aurothioglucose, aurothiosulfate and aurothiomalate are presented.

Animals↗

PubMed1980

Electron microscopic demonstration of metals in rat mast cells. A cytochemical study based on an improved sulphide silver method.

This paper describes a modification of a cytochemical method for the demonstration of heavy metals. The well localized precipitate in the mast cell granules, which is also present in granules that have been separated from the cell, suggest that the metals are localized in the granules. It is demonstrated that "mast cell" grown cultures do not contain precipitate. The chelating and histamine inhibiting agent 8-hydroxyquinoline produced no changes in the histochemical pattern of the mast cell granules before nor after treatment with the histamine liberator 48/80 which provokes a release of granules from the cells. These observations suggest either that the metal (zinc) is bound to the granules in such a manner that the chelating agent cannot chemically, or based on the configuration of the metal-containing molecule, reach the metal and thereby prevent its transformation to a metal suphide.

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