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  • 1
    Electronic Resource
    Electronic Resource
    Springer
    Virchows Archiv 380 (1978), S. 335-339 
    ISSN: 1432-2307
    Keywords: Melanin ; Glial Melanin ; Melanosis of the dentate nucleus ; Melanosis cerebelli
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Melanosis of the dentate nucleus is an extremely rare condition in which pigment is formed within the cytoplasm and cytoplasmic processes of astrocytes in the dentate nucleus and the cerebellar granular cell layer. The pigment occurs as irregular polygonal structures of rather homogeneous appearance unlike granular neuromelanin located within neurons of the substantia nigra. The diameter of these pigment masses may reach 30 Μm or more. Their absorption of visible light increases steadily towards the shorter wavelengths, and the material is virtually opaque in the violet and ultraviolet region, resembling melanin in this respect. Since the absorption spectrum described by Rabl exhibited a small peak at 525 nm, he regarded the pigment as the hemoglobin derivative pentdyopent. We were unable, however, to confirm this observation. On X-ray diffraction the pigment produced a sharp reflex at 4.93 å as did synthetic melanin prepared from dopamine (but not melanin prepared from serotonin). These observations supported the assumption made by others based on histochemical evidence, that the pigment in the dentate nucleus may belong to the group of melanins. Presumably the glial melanin somehow arises from the metabolic pathway leading to DOPA. An astrocytic site of melanin formation other than in the cerebellum has not been previously described, and this melanin differs in appearance from the granular neuromelanin found in neurons in the substantia nigra. Thus “cerebellar glial melanin” contrasts with neuromelanin of the substantia nigra both in its site of formation and in its morphology. The underlying cause of the glial melanin formation in the cerebellum is not known. There are six cases in the world literature, 5 females and 1 male, ranging in age from 58 to 103 years. Involutional alterations in metabolism related to endocrine factors may possibly play an important part. To the best of our knowledge cerebellar melanosis is of no clinical relevance.
    Type of Medium: Electronic Resource
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  • 2
    ISSN: 1432-0533
    Keywords: Melanin ; Melanosomes ; Ultrastructure ; Infrared spectrophotometry ; X-ray diffraction
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Melanosomes and isolated melanosomal fragments (melanin particles) originating from gangliocytes (substantia nigra), astroglia (melanosis cerebelli), and melanocytes (melanotic meningeoma; metastases of melanoblastoma; melanosis thalami of the goat) were compared with synthetic melanins prepared from dopamine and serotonin, respectively. Samples were examined by electron microscopy, X-ray diffraction analysis according to Debye-Scherrer and by infrared spectrophotometry, and the results were evaluated with regard to characteristic features as they may relate to specific cell types or chemical structures. On electron microscopy all three types of melanosomes could be differentiated unequivocally as could the two synthetic melanins. Thus, there were similarities between synthetic melanin from dopamine and the gliogenic melanins of the cerebellum; the synthetic melanin from serotonin resembled melanin of melanocytes. X-ray diffraction analysis yielded 2-4 Debye diffraction rings with all human and synthetic samples, suggesting short range orders between 3.8 to 5 Å the sample obtained from a goat with thalamic melanosis showed a specific reflex pattern. While diffraction patterns of some melanins were partially identical, in particular that of melanin from dopamine and melanin of substantia nigra and dentate nucleus, respectively, they were different for the various melanocytic melanins. Further investigations are required to determine whether these differences are due to disparities in basic chemical structures or conformations or else, to particular compositional features of the various types of melanocytes as they arise from benign or malignant tumors or a specific species. Infrared spectrophotometry at higher wave numbers revealed the well known patterns of melanins, which are not, however, very suitable, for their further differentiation. At lower wave numbers (‘fingerprinting’) melanin of substantia nigra and the glial melanin in melanosis cerebelli yielded additional absorption bands of identical configuration. In contrast to melanin from dopamine, melanin from serotonin exhibited a closely similar absorption pattern in this spectral range, suggesting that the neuroectodermal melanins may contain a component possibly arising from serotonin.
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    Springer
    Journal of neurology 206 (1974), S. 117-128 
    ISSN: 1432-1459
    Keywords: Trace elements ; Aging of the brain ; Copper ; Zinc ; Calcium ; Magnesium ; Iron
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Description / Table of Contents: Zusammenfassung In der Frontal- und Occipitalhirnrinde, in Hippocampus, Mandelkern, Striatum, Thalamus, Pallidum, S. nigra, Nucl. ruber, Ncl. dentatus, Oliva inf. und Centrum semiovale wurde die Konzentration von Fe, Zn, Cu, Mg und Ca bestimmt. Bei Fe und Cu konnte ein bestimmtes Verteilungmuster für diese Gebiete ermittelt und statistisch gesicher werden. Für Zn, Ca und Mg waren keine signifikanten regionären Unterschiede nachweisbar. In den untersuchten Altersgruppen ist für diese 5 Elemente eine Altersabhängigkeit nicht erkennbar.
    Notes: Summary The elements iron, copper, zinc, magnesium and calcium were quantitatively determined in several regions of the human brain, including frontal and occipital cortex, hippocampus, n. amygdalae, striatum, thalamus, pallidum, substantia nigra, n. ruber, n. dentatus, oliva inferior and centrum ovale (white matter). Samples were obtained on autopsy from a total of 29 brains at time periods ranging from 12 to 48 hrs after death. Age groups and number of cases (in parentheses) were as follows: 0–2 years (6), 30–40 years (2), 41–50 years (4), 51–60 years (4), 61–70 years (9) and 71–80 years (4). Samples were analysed by means of atomic absorption spectrophotometry following appropriate sample preparation. Results are based on unit dry weight. When the different age groups were compared to each other both the overall means of the five elements studied and the mean concentrations of individual regions remained essentially constant from 31–80 years of age. Values of adult brain were, however, generally higher than those of infant brains (0–2 years of age), changes in levels apparently taking place during infancy and possibly adolescence. Regionally, iron and copper were found to be distributed according to a statistically characteristic pattern; the iron content of the pallidum, putamen, substantia nigra and the caudate nucleus was significantly higher, that of the inferior olive lower when the concentrations of the frontal cortex were arbitrarily used as a reference point. Likewise, copper levels of the substantia nigra were higher, that of the centrum semiovale lower than that of the frontal cortex (P〈0.01). Although no such distinctions could be made regarding the distribution of zinc, magnesium and calcium compared to frontal cortex, the overall regional variation was significant even for these elements when the data were submitted to a one-way analysis of variance (e.g. P〈0.01 for zinc and magnesium). It should be noted that the variance of the means of iron, copper, zinc and calcium was great for some of the anatomical regions, while much less so for others for reasons as yet unknown. The results indicate that in human brain the elements examined undergo little change during adulthood up to the beginning of senescence, and regional differences persist throughout this life span.
    Type of Medium: Electronic Resource
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