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Biomedical subjects

G Danscher

Publications and source records attributed to G Danscher.

At least 109 records · Page 6Linked to original sources
PubMed1987

Effects of selenium on toxicity and ultrastructural localization of silver in cultured macrophages.

The effects of selenium on cellular toxicity and histochemical distribution of silver were examined in a cell culture system of mouse peritoneal macrophages. Selenium caused a significant delay in the appearance of coagulation necrosis induced by high silver concentrations and reduced the cytostatic effect of lower doses of silver when long-term toxicity was examined. Furthermore, selenium increased the amount of silver that could be visualized by autometallography. The additional silver made available for this histochemical demonstration was located in the cytosol as well as in lysosomes, the sole localization of silver when selenium was not administered.

Animals↗
PubMed1987

Autometallography: tissue metals demonstrated by a silver enhancement kit.

In biological tissue, minute accumulations of gold, silver, mercury and zinc can be visualized by a technique whereby metallic silver is precipitated on tiny accumulations of the two noble metals, or on selenites or sulphides of all four metals. In the present study a silver enhancement kit, primarily intended for the amplification of colloidal gold particles, has been used to demonstrate these catalytic tissue metals. Sections from animals exposed intravitally to aurothiomalatate, silver lactate, mercury chloride, sodium selenite or perfused with sodium sulphide were subjected to a commercial silver enhancement kit (IntenSE, Janssen Pharmaceutica). It was found that the kit performs adequately to the silver lactate gum arabic developer and to the photographic emulsion technique. The kit can be used as a silver enhancement medium for the demonstration of zinc by the Neo-Timm and selenium methods and for demonstration of gold, silver, and mercury in tissues from animals intravitally exposed to these metals. It can also be used for counterstaining silver treated osmium fixed tissues embedded in plastic.

Animals↗
PubMed1987

Cytochemical demonstration of mercury deposits in trout liver and kidney following methyl mercury intoxication: differentiation of two mercury pools by selenium.

The amount and the ultrastructural distribution of mercury was studied in seven different organs of rainbow trout (Salmo gairdneri) fingerlings following exposure to methyl mercury (MeHg)-contaminated fodder for periods of 2 and 7 weeks. The amounts of mercury retained by the whole fish and the selected organs were determined by measuring the uptake of 203Hg-labeled MeHg. Spleen, liver, and kidney had the highest concentrations after both experimental periods, while the largest relative increases were found in brain, muscle, and kidney. The subcellular distribution of mercury accumulations was demonstrated cytochemically in liver and kidney using the silver enhancement method by which accumulations of mercury-sulfides and/or mercury-selenides are made visible for light and electron microscopy. When sections prepared from the liver and kidney from fish, injected with selenium 2 hr prior to being killed, were compared with those of fish not treated with selenium, two distinct pools of mercury could be demonstrated, the HgS pool, and the HgSe pool. The HgS pool, supposed to represent inorganic mercury, was found exclusively within lysosomes. The increase of this pool from 2 to 7 weeks was most pronounced in the kidney. The HgSe pool, supposed to represent methyl mercury, was shown by the presence of silver deposits at new locations as well as by an increase in the amount of deposits within lysosomes. The new locations included (1) secretory-like vesicles and the bile canaliculi of the liver, suggesting a biliary excretion of this mercury pool; (2) microvilli and endosomes of kidney tubular cells, suggesting a glomerular filtration and subsequent reabsorption; and (3) mitochondria of proximal tubule cells.

Animals↗
PubMed1987

A quantitative evaluation of the neurotoxic effect of silver on the volumes of the components of the developing rat hippocampus.

The volumes of the components of the hippocampus of rats subjected to subcutaneous injections of silver during the first 4 postnatal weeks were compared to those of littermate controls. Of the 14 components measured, only the pyramidal cell layer was found to be significantly smaller in the treated animals. These findings indicate that the perikaria of the pyramidal cells are either the first elements in the developing hippocampus to show signs of silver toxicity or that they are the selective sites of silver neurotoxicity. The volumetric approach is shown to be a sensitive means by which small localized neurotoxic effects can be detected.

Animals↗
PubMed1987

Zinc-containing 7S-NGF complex. Evidence from zinc histochemistry for localization in salivary secretory granules.

7S-NGF is a pro-protein containing a neurotrophic subunit, beta-NGF, which has been localized by immunocytochemistry to the granules of granular convoluted tubule (GCT) cells in certain murine salivary glands [Watson et al., Anat Rec (1985) 213:365]. The 7S-NGF pro-protein contains zinc and is stabilized by zinc ions [Pattison and Dunn, Biochemistry (1976) 15:3696]. In the present work, dithizone, toluene sulfonamide quinoline (TSQ), and neo-Timm's methods for zinc were used to determine whether zinc histochemistry could be used to visualize the zinc associated with the 7S-NGF complex and, if so, whether zinc histochemistry might corroborate the reported localization of the 7S-NGF complex in GCT secretory granules. The results indicate that intensity of zinc staining varies with the reported variations in NGF levels in different salivary glands, and that the zinc is selectively concentrated in the GCT secretory granules. We suggest that zinc histochemistry may be a useful marker for the presence of the zinc-stabilized 7S-NGF pro-protein.

Animals↗
PubMed1986

Release of zinc sulphide accumulations into synaptic clefts after in vivo injection of sodium sulphide.

The fate of sulphide-bound zinc was studied in synaptic boutons of the telencephalon after intracerebral injection of sodium sulphide. After short survival times (30 min), zinc was found in boutons located in synaptic vesicles, later in vesicles and in the synaptic clefts, and at long survival times (48 h) zinc was located solely in the extracellular space. The present data suggest that: zinc, when bound to sulphide, is released into the synaptic cleft in a time dependent way; and different zinc-containing boutons have different turnover periods, the hippocampal giant mossy fiber boutons being the tardiest to empty their zinc sulphide content.

Animals↗
PubMed1986

Histochemical demonstration of two mercury pools in trout tissues: mercury in kidney and liver after mercuric chloride exposure.

Juvenile rainbow trout (Salmo gairdneri) were exposed to 100 ppb mercury (as HgCl2) in the water for 14 days. Concentrations of mercury in water and fish organs were monitored using radiolabeled mercury. Tissues from kidney and liver were fixed, and sections were developed by autometallography, a method whereby accumulations of mercury sulfides and/or mercury selenides are silver amplified. In the kidney, mercury was found within lysosomes and extracellularly in the basal lamina of proximal tubules. In the liver, mercury was found within lysosomes of the hepatocytes. Additional groups of mercury-exposed trout were subjected to selenium (as Na2SeO3), administered intraperitoneally 2 hr before fixation. Following this treatment, additional mercury could be visualized in the kidney circulatory system, including glomeruli, and in the nucleus and endoplasmic reticulum of liver cells. It is suggested that the mercury visualized prior to selenium treatment represents inorganic mercury, while additional mercury visualized after selenium administration represents an organic form.

Animals↗
PubMed1986

Localization of mercury in CNS of the rat. I. Mercuric chloride (HgCl2) per os.

Adult Wistar rats of both sexes were exposed to mercuric chloride (HgCl2) through drinking water (20 mg HgCl2 liter-1 distilled water) ad libitum during an 8-month period. Animals were subsequently sacrificed by transcardial perfusion with glutaraldehyde. Coronal sections of the brain and cervical spinal cord were examined according to a histochemical technique based on a physical development process which renders mercury deposits visible. Mercury was found unevenly distributed in the brain and spinal cord with the heaviest deposits found within the motor nuclei of the rhombencephalon. In cerebral cortex, the highest concentration of mercury was found in the striate area. Mercury was also localized within the deep nuclei of cerebellum; none was found within Purkinje cells. A proportionately high amount of mercury was additionally found in the anterior horn motoneurons of the spinal cord. In general, mercury was found primarily within neurons, but it was also observed in the cytoplasm of glia and ependymal cells.

Administration, Oral↗
PubMed1985

Entorhinal and prepiriform cortices of the European hedgehog. A histochemical and densitometric study based on a comparison between Timm's sulphide silver method and the selenium method.

The Timm and selenium staining techniques, based on silver amplification of endogenous zinc, produce an electron-dense precipitate in boutons. The staining characteristics of the two methods were compared by examining two allocortical regions, prepiriform cortex and entorhinal cortex, in the brain of the European hedgehog. In the 3 layers of prepiriform cortex and the 6 layers of entorhinal cortex the methods revealed sublayers, which allows a precise delimitation of areas 28M, 28L, a short transition zone, and the prepiriform cortex. The lamination of the entorhinal cortex of the hedgehog is similar to that found in the rat, but appears less distinct. This may point to a lower degree of afferent organization. For light microscopical investigations, the selenium technique appears superior to Timm's method because it produces a more distinct zonation pattern.

Animals↗
PubMed1985

Intravesicular localization of zinc in rat telencephalic boutons. A histochemical study.

A transition metal (presumably zinc) has been localized inside the synaptic vesicles of rat telencephalic boutons which make asymmetric synaptic contacts (Gray type I). A modification of Timm's sulphide-silver method for electron microscopy was applied to different areas of the rat forebrain: olfactory bulb, septum, caudate-putamen, amygdaloid complex, neocortex, entorhinal cortex and different parts of the hippocampal formation, viz. subiculum, stratum radiatum and oriens of both regio superior (CA1) and regio inferior hippocampi (CA3), the mossy fibre zone and the hilus fascia dentata and stratum moleculare in the gyrus dentatus. It was observed that the Timm staining in all these areas was located in synaptic boutons. Labelled boutons displayed a population of round clear vesicles and few dense core vesicles and made asymmetric synaptic contacts on dendritic spines. Silver granules in these boutons were confined to only a minor fraction of the round clear vesicles (approximately 10%). Labelled boutons occasionally showed silver granules in the synaptic clefts. The possible involvement of vesicular zinc in synaptic transmission is discussed.

Animals↗
PubMed1985

Selenium in the anterior pituitary.

Selenium accumulated in the anterior pituitary of the rat after intraperitoneal injection of NA2Se03. Selenium is bound to a cation (most likely Zn++) and is ultrastructurally located in lysosomes and secretory granules.

Animals↗
PubMed1985

Selenium in the Paneth cells.

Two histochemical methods, Timm's sulphide silver method and the selenium method reveal the presence of two pools of metal ions in the Paneth cells. Ultrastructurally one pool is located in the secretion granules, the other in the cytoplasm.

Animals↗
PubMed1985

The dithizone, Timm's sulphide silver and the selenium methods demonstrate a chelatable pool of zinc in CNS. A proton activation (PIXE) analysis of carbon tetrachloride extracts from rat brains and spinal cords intravitally treated with dithizone.

From rats intravitally treated with dithizone (diphenyl-thiocarbazone) brains and spinal cords were removed and freeze-dried. The dithizonates present in the CNS tissue were extracted with carbon tetrachloride and subjected to a multielement analysis (proton activation, PIXE). It was found that the extract contained two metals. Most of the metal was zinc, but small traces of copper were also detected. Because prior treatment with the chelating agent, dithizone, can block both the Timm and the selenium metal staining methods, it is suggested that the three techniques label predominantly zinc in the neuropil (DTS-zinc).

Animals↗
PubMed1985

Intracellular accumulation of mercury in the anterior pituitary of rats exposed to mercuric chloride.

A histochemical technique has been used to reveal mercury deposits by light and electron microscopy in the anterior pituitary of adult rats. After administration of mercuric chloride either in the drinking water or by intraperitoneal injection, deposits were found within lysosomes and secretory granules in somatotrophs, thyrotrophs, follicular cells, and marginal cells. The amount of mercury deposited was proportional to the dose of mercuric chloride given. Significantly more mercury was found in rats given intraperitoneal injections compared to those intoxicated with mercuric chloride in the drinking water. Mercury was retained in the cells for at least 4 months after the last injection although the amount of deposits decreased in this period.

Animals↗
PubMed1985

Gold in the ovary of rats exposed to sodium aurothiomalate.

The ultrastructural localization of gold in the ovary of rats injected intraperitoneally with sodium aurothiomalate has been demonstrated using a histochemical technique that visualizes minute traces of gold. Gold was visualized in the oocyte within the cortical granules and in lysosomes of theca interna cells and interstitial cells.

Animals↗
PubMed1985

Selenium in the anterior pituitary of rats exposed to sodium selenite: light and electron microscopic localization.

Metal selenide accumulations were demonstrated in the anterior pituitary of the rat by a histochemical technique at light and electron microscopic levels. After administration of sodium selenite either by drinking water (2.5 to 15 ppm) or by ip injection (5 to 20 mg/kg body wt), intracellular accumulations were found in secretory granules and lysosomes of the somatotrophs, thyrotrophs, corticotrophs, and the gonadotrophs. The amount of countable deposits increased with increasing doses, whether selenite was given in drinking water or by ip injection. Localization of deposits was independent of route of administration. Following a single ip injection of 5 mg sodium selenite/kg, a steadily increasing amount of visible deposits was seen throughout the first week. After this peak the deposits started to decrease but could still be found after 2 weeks. Selenium may possibly create bonds to endogenous zinc in the anterior pituitary as has been suggested for the brain.

Animals↗
PubMed1985

Silver amplification of mercury sulfide and selenide: a histochemical method for light and electron microscopic localization of mercury in tissue.

A method for light and electron microscopic demonstration of mercury sulfides and mercury selenides in mammalian tissue is presented. Silver ions adhering to the surface of submicroscopic traces of mercury sulfides or selenides in the tissue are reduced to metallic silver by hydroquinone. Physical development thereupon renders deposits of mercury sulfides or mercury selenide visible as spheres of solid silver. Examples of localization of mercury in the central nervous system and various organs from animals exposed to mercury chloride or methyl mercury chloride with or without additional sodium selenide treatment are presented. Selenium treatment results in a considerable increase in the amount of mercury that can be made visible by silver amplification. After mercury chloride treatment, most of the mercury is localized in lysosomes and is only rarely seen in secretory granules. After simultaneous selenium treatment, mercury is also found in nuclei of proximal tubule cells in the kidney and in macrophages. The "sulfide-osmium" method for ultrastructural localization of mercury suggested by Silberberg, Lawrence, and Leider (Arch Environ Health 19:7, 1969) and the light microscopic method using a photographic emulsion suggested by Umeda, Saito, and Saito (Jpn J Exp Med 39:17, 1969) have been experimentally analyzed and commented on.

Animals↗