Quantitative analysis of total gangliosides and of ganglioside composition by HPTLC has been carried out on the gray matter of frontal cerebral cortex of six brains from Down's syndrome (DS) adults, six age-matched controls, six Alzheimer's disease (AD) adults, and six controls matched for age with the AD brains, as well as on three DS and six control cerebellum specimens. In addition, the analyses were carried out on specimens of corpus callosum of five adult DS and five control brains. No abnormalities were found in the gangliosides of DS corpus callosum. In DS frontal cortex, the concentration of total gangliosides was reduced, and there was a decrease in the fraction of GT1b and GD1b, and an increase in those of GT1a, GD3, GM1 and GM2; the ratio of total b-series to a-series gangliosides was decreased. Very similar abnormalities were found in the gangliosides of DS cerebellum. In AD frontal cortex, by contrast, the total gangliosides and their composition were normal by comparison with age-matched controls, with the minor exception of reductions in the fractions of GQ1b and GT1L. It is concluded that abnormalities in gangliosides exist in the brain in DS that are unrelated to AD-type pathology and may reflect developmental disturbances.
The effects of neonatal thyroid deficiency or hyperthyroidism on the development of neurones containing certain neuropeptides was examined in the brains of rats killed at two weeks of age. Five brain areas were dissected and extracted for radioimmunoassay measurement of vasoactive intestinal polypeptide (VIP), somatostatin, cholecystokinin octapeptide (CCK), substance P and neurotensin, whilst corresponding immunocytochemical data were obtained from a quantitative morphological analysis of cell bodies in the cingulate cortex. The two methods of analysis did not always agree, but in hypothyroidism both the concentration of VIP and the number of cells containing VIP-like immunoreactivity were significantly decreased in the anterior and posterior cingulate cortex. In contrast to these effects on the late maturing VIP neurones, the earlier developing somatostatin system was relatively unaffected, whilst neuropeptides localized in cortical fibres rather than cell bodies (such as substance P and neurotensin) were found by radioimmunoassay to be elevated. Hyperthyroidism had less marked effects than neonatal thyroidectomy, although the concentration of CCK (but not the number of immunostained cells) was significantly increased in the cingulate cortex. Radioimmunoassay results from three subcortical areas showed a decrease in VIP concentration in the hypothyroid hypothalamus, and in hyperthyroidism significant elevations of VIP in the basal ganglia, somatostatin in the hypothalamus and CCK in the hippocampus. It appears that in the brain areas studied thyroid disorders result in dis-synchronous shifts in the developmental patterns of the different neuropeptides, and that the effects of thyroid hormone on peptides as on other transmitters are critically dependent on the developmental profile of the system in question.
Purchased service arrangements, establishing in-house professional pathology services, conducting technical component histology within a dermatology practice, and electronic medical records technology donations are ways that dermatology practices are responding to the current health care delivery and payment changes. This article will provide a general framework for navigating the compliance risks and structure considerations associated with these relationships between dermatologists and pathologists.
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