Biomedical subjects
Publications and source records attributed to M Lucas.
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In isolated pancreatic acinar cells from the guinea pig stimulation of enzyme secretion by carbamoylcholine is slightly diminished in the absence of extracellular Ca. LaCl3 in a concentration, which does not influence the secretory response to carbamoylcholine, nearly completely abolishes 45Ca uptake by cells, indicating that Ca uptake is not necessary for secretion. In cells preloaded with 45CaCl2, addition of carbamoylcholine leads to an immediate release of 45Ca, which can be blocked by atropine or 8-(N,N-diethylamino)-octyl 3,4,5-trimethoxybenzoate and is not influences by LaCl3 in concentrations, which do not inhibit secretion. A similar release of 45CaCl2 from preloaded cells is obtained by addition of the mitochondrial inhibitors antimycin A, carbonylcyanide p trifluoromethoxyphenylhydrazone (FCCP), and oligomycin. Possibly due to markedly diminished ATP levels, neither antimycin A nor FCCP act as secretagogues, both compounds being inhibitors of secretion. Oligomycin, which decreases ATP levels only to 20%, stimulates secretion. Mitochondria and microsomes from pancreatic tissue are able to accumulate 45Ca. Mitochondrial 45Ca uptake can be driven by ATP or active respiration and is inhibited by NaN3, oligomycin, antimycin A or FCCP. Microsomal 45Ca uptake is ATP-dependent. NaN3 and mitochondrial inhibitors have no influence on microsomal 45Ca uptake, which is stimulated several-fold by oxalate. The results support the assumption, that in the guinea pig pancreas Ca mobilization from intracellular stores is necessary to initiate secretion. Due to their ability for an active accumulation of45Ca both mitochondria and microsomes could serve as intracellular calcium stores.
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The culture of fetal cells obtained by amniocentesis has become a useful and often reassuring investigation for couples having an increased risk of giving birth to an abnormal child. The present report illustrates the experience at one center where the work has been carried out for a number of years.
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This study deals with the problem of distribution of the 46 centromeres on the human metaphase plate after treatment with colchicine and hypotonic shock. The location of the centromeres was recorded for 400 metaphases in which the chromosomes were identified by bands. A quantitative analysis of chromosome distribution ascertains the absence of proximities between homologous chromosomes. The already known ones between acrocentric chromosomes are found at a very high level. The nature and intensity of these proximities vary from one sample to another as is the case between heterologues. A three-dimensional graphic technique is proposed to summarize all of the interchromosome proximities.
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Scouring and vomiting was induced in piglets by experimental infection with a field strain of rotavirus. Virus or viral antigen was detected in the small intestine by the fluorescent antibody technique and virus could also be demonstrated in infected tissue culture cells by immuno-fluorescence. Progeny particles in the epithelial layer of the small intestine were identified by electron microscopy. Three morphological types could be distinguished, often associated with electron-dense inclusion, and infected cells, though small in number, were present throughout the length of the small intestine.
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A case of adrenal insufficiency occurring after unilateral radical nephrectomy is presented. Recommendations for identification and treatment of this condition are discussed.