A glial progenitor cell that develops in vitro into an astrocyte or an oligodendrocyte depending on culture medium. Indications are that calcitonin does not enhance bone formation or alter the number of osteoblasts Rasmussen and Bordier, 1974. Iodine flow and iodine compartment of the colloid. Development of Other Photochemical Activities. This implies a possible involvement of phospholipids in hormone secretion.
The peak period of astrocyte genesis coincides with the rapid growth of blood vessels65-67 and pial surface, the elaboration of dendritic arbors, and the establishment of synapses both from cortical afferents and from intracortical circuits. Elustuse Janoff and Basch 1971 described the presence of elastase in lysates of alveolar macrophages, and Werb and Gordon 1975b studied the secretion of this enzyme by thioglycollate-induced macrophages. The mammalian thyroid gland is also responsible for the elaboration, storage, and secretion of a second type of hormone, calcitonin, which lowers the calcium concentration of blood. The interstitial position of parafollicular cells reported in some light microscope studies Carvalheira and Pearse, 1967a; Gabe and Martoja, 1969; Salzer, 1971 , namely, outside the basement membrane, has not been upheld by electron microscope examination of thyroid glands Lietz, 1971. During climax, most of the values are near 30 impulses per second Fig.
Recent modifications of the method include a fluorescence technique involving the acridine dye coriphosphine 0 Bussolati et al. Can J Physiol Pharmacol 1992; 70:S255-S259. During postclimax the development of these formations is more restricted. In these experiments, the lymphokine preparation did not induce cell mitosis. Clonal analysis of astrocyte diversity in neonatal rat spinal cord cultures. This process, referred to as micropinocytosis, differs from macropinocytosis in that it cannot be inhibited by cytochalasin B Allison et al.
This hypothesis is confirmed by a recent study in which no trace of T, was found in the blood of these animals Taurog et al. The result is a storage of thyroglobulin and iodine, since electrophoresis of the serum does not reveal any trace of T,. Orzi F, Zoli M, Passarelli F et al. Radioautographic investigation of gliogenesis in the corpus callosum of young rats. Namba Y, Tomonaga M, Kawasaki H et al. Mol Brain Res 1994; 25:217-224.
Several histological studies have demonstrated the effect of hypocalcemia on parafollicular cells. Olivereau 1970 , on the basis of histochemical staining, states that degranulation of parafollicular cells occurs during hibernation. The regression of ergastoplasmic formations also suggests a decrease in protein synthesis, especially of thyroglobulin. Though thyroglobulin synthesis is high, iodination is low. In some species, such as the human Pearse, 1966a , cat Kameda, 1971b , and dog Kameda, 1971a; Roediger, 1973b; Teitelbaum et al. All these, like parafollicular cells, are likely to have as at least one of their functions the synthesis and secretion of polypeptides.
Akiyama H, Kawamata T, Yamada T et al. Glutamate metabolism in rat cortical astrocyte cultures. Excitatory amino acid receptors in glial progenitor cells: Molecular and functional properties. Shibuki K, Gomi H, Chen L et al. Transmitter receptor and uptake systems in astrocytes and their relation to behaviour. Astrocytes can change morphology and expression of many molecules, including surface gangliosides, intermediate filaments, enzymes, and stress proteins, in response to pathological conditions see for examples refs.
Fischer J, Holubar J, Malik V. In cultures of cells exposed to 10 pg of endotoxin per milliliter of medium for 72 hours, the levels of lactate dehydrogenase and leucine-2-naphthylamidase increase about twofold over control values. The sonically disintegrated cells yielded an insoluble factor which, when injected subcutaneously in guinea pigs, caused granuloma formation. Please address all inquiries to the Publishers: R. J Physiol Lond 1991; 436:169-193.
The production and release of pyrogen from mononuclear phagocytes and from tissues such as lung, spleen, and lymph nodes is greatly increased by phagocytic stimuli Bodel and Atkins, 1967; Atkins et al. Glutamate neurotoxicity in culture depends on the presence of glutamine: Implications for the role of glial cells in normal and pathological brain development. Collagenase Collagenase plays a major role in both normal tissue turnover and remodeling and in the destruction of collagen, which occurs in most acute and chronic inflammatory reactions. These interactions may well serve to condition and maintain astrocyte shape see below. New York: Raven Press, 1976. Biochem Biophys Res Commun 1992; 182:593-599. He found that parafollicular cells in the dog are distributed mainly in the part of the thyroid supposedly developed from the ultimobranchial body.
Over a period of minutes the time is increased at low temperature or in leaves illuminated after prolonged etiolation, C,,, is replaced by C,,,. Both these results may be due to a stimulation of esterification, detergent micelles having the same effect as that of oil emulsions described previously. It seems unlikely therefore that relationships established in vivo would persist unchanged. Two major chlorophyll-protein complexes are recognized. San Diego: Academic Press, 1993:331-354. Eur J Neurosci 1994; 6:936-942. Mansour H, Asher R, Dahl D et al.