Biomedical subjects
Publications and source records attributed to G Danscher.
A histochemical method modified for ultrastructural studies of mercury induced changes is described. Rat neurons from areas known to be influenced by mercury are used as examples. The histochemical reaction, suggested to be caused by polymercury sulphide complexes, is localized to "dense bodies" where it is visible 14 days after initiation of peroral mercury treatment (20 mg HgCl2/l drinking water).
A technique for multi-element analysis of brain tissue by proton induced X-ray emission spectroscopy (PIXE) is described and data from analysis of fixed and unfixed samples from rat hippocampus, neocortex, amygdala, and spinal cord is presented and commented on. The atoms present in the tissue are bombarded with protons which causes the ejection of electrons from the inner shells. When the "holes" are refilled with electrons from outer shells, X-ray quanta characteristic for each element are emitted. Using a high resolution energy dispersive detector a complete X-ray spectrum of the specimen can be recorded in a single measurement. Detection limits less than or approximately 5 p.p.m. of dry matter are obtained for most elements with atomic number greater than 14 (silicon). Around 13 elements were found in concentrations above the detection limits. The grand means for non-fixed hippocampi were e.g. for Zn - 120 p.p.m.; Rb - 20 p.p.m.; Fe - 150 p.p.m.; Pb - 3 p.p.m; Ni - 5 p.p.m.
The amounts of zinc, copper, and lead in the rat spinal cord were determined by means of flameless atomic absorption spectrophotometry. Zinc was present in a concentration about 100 p.p.m. (dry weight), copper in a concentration about 5 p.p.m., and lead in slightly more than 1 p.p.m. Analysis of various levels along the cranio-caudal axis of the rat spinal cord revealed differences in the heavy metal content. The Timm sulfide silver staining method has demonstrated that metals in the spinal cord have a distinct regional distribution. To obtain a differentiation between the stainable metals, the effects of six chelating agents (DEDTC, dithizone, oxine, EDTA, dipyridyl, and phenantroline) on the Timm pattern were tested. EDTA left the pattern unchanged, while the other compounds showed individual differences in their influence on the Timm pattern, suggesting that the heavy metal pattern of the spinal cord consists of multiple compartments. The effect of intravital multiple low dose treatment with three of the chelating agents on the histochemical pattern and the metal content of the spinal cord was also investigated. It was found that a decrease in the metal content was not followed by reduction of stainability and vice versa.
The absolute volumes of the hippocampal and subicular cortical layers in the rat were determined. The boundaries of the various layers were defined on series of sections made through the entire hippocampal region of five rats and stained according to the Timm sulfide silver technique. Coordinates representing the boundaries of the layers on selected sections were fed into a mini-computer programmed to calculate the volume of the layers from the areas of the profiles and the distances between the sections. The distribution of the layers indicates that they constitute the same proportion of the volume of the dorsal and ventral divisions of the hippocampal region, with the exception of the structures lying in regio inferior and regio superior. Although the combined regio superior and regio inferior components of the layers of Ammon's horn occupy the same percentage of the volume of the dorsal and ventral hippocampal regions, the regio superior components occupy a larger percentage of Ammon's horn in the dorsal region than they do in the ventral region. The inter-animal variations in the volumes of the various layers indicate that it is possible to describe quantitatively the subdivisions of the hippocampal region with a precision that is compatible with comparative studies.
Modifications of the Timm sulphide silver method for the demonstration of heavy metals are described. To improve the structural preservation of the tissues perfusion with a glutaraldehyde fixature is employed before perfusion with the sodium sulphide solution. For the subsequent staining for light and electron microscopy, procedures for plastic embedding, paraffin embedding and cryostat sectioning are presented. Examples from several tissues are shown, including the pituitary, pancreas, intestine, tongue, kidney, testis and brain. The staining of autolytic, postmortal human brain tissue is demonstrated.
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