Visualization of opiate receptors in the locus coeruleus of rats: high resolution radioautography after administration of a tritiated met-enkephalin analog]

Opiate receptor sites were visualized by high resolution radioautography in the locus coeruleus of the Rat following intraventricular injection of the met-enkephalin analogue FK 33-824 tritiated with a high specific activity (3H-FK). After administration of a tracer dose of 3H-FK, more than 75% of the radioactivity detected in the locus coeruleus is specifically bound to opiate receptor sites. These are distributed both between and inside neuronal perikarya. After administration of 3H-FK at high concentration, electron microscope radioautography shows the presence of specific opiate binding sites at the level of axo-somatic and axo-dendritic synaptic junctions. These synaptic binding sites could correspond to receptor sites for endogenous enkephalins.     

Growth of follicular cells in aphids. A cytophotometric and autoradiographic study

Riassunto I nuclei delle cellule follicolari degli Afidi mostrano nell'ambito di uno stesso tollicolo variazioni pressochè continue nel contenuto di DNA. Dopo brevi intervalli di tempo dall'iniezione di timidina tritiata, una elevata percentuale di questi nuclei risulta marcata. È stata fatta l'ipotesi che ogni ciclo di poliploidizzazione in questi nuclei si componga di un lungo periodo di sintesi di DNA seguito da uno breve di intersintesi. La lunghezza del periodo sintetico è dovuta presumibilmente all'asincronia nella sintesi di DNA che esiste tra i vari elementi cromatici in uno stesso nucleo.     

Ultrastructural autoradiographic study of blast cells in the mouse thymus Interest for radioleukemia research

Summary Ultrastructural autoradiographic studies of mouse thymic blast cells after H3 Tdr injection show that their fine nuclear structure is related to their position in the cell cycle. The variations in the composition of the subcapsular blast cell population during radiation-induced leukemogenesis indicate kinetic changes in thymic lymphopoiesis, which are probably due to the oncogenic process.     

Interaction of epidermal growth factor with human fibroblasts in culture: an autoradiographic study at the ultrastructural level]

The potent mitogen epidermal growth factor (EGF) binds to specific receptors on human fibroblasts. In the present study we have used a quantitative EM autoradiographic approach to visualize the events involved in the binding process. When 125I-EGF is incubated at 4 degrees C for 120 min, labeled EGF primarily localizes to the plasma membrane of the fibroblast but when incubated at 37 degrees C for 120 min., over 2/3 of the labeled material is internalized by the cell. The internalized radioacitivity is primarily localized to lysomes. These studies demonstrate a temperature-dependent internalization of EGF following initial binding to specific plasma membrane receptors.     

Demonstration of cobalt in histological sections using ion microanalysis by high mass resolution : application to the study of experimental chronic epilepsy in the rat]

Cobalt is specifically detected in ion microanalysis by high mass resolution. This method allows detection of the remaining cobalt in histological sections of Rat's cortex, after treatment by topic application of cobalt powder and demonstrates a diffusion of the metal into the epileptic area.     

Autoradiographic study of the penetration of non-histone chromatin proteins into differentiating cells

Summary Attention has previously been drawn to a specific effect of NHCP on embryonicPleurodeles cell differentiation. With a modified NHCP labelling technique, autoradiography has revealed a cytoplasmic concentration of labelled NHCP and has not revealed any difference between homospecific and heterospecific NHCP penetration.This work has been supported financially by research grants from the C.N.R.S. (ERA No. 327 and ATP No. 4310 on the cellular differentiation), and INSERM (No. 711019).The authors wish to extend their thands to Dr.Mazarguil who kindly initiated us in the techniques of enzyme binding. Many thanks are also due to Mr.Hawks for most valuable help in correcting the English.     

Ultrastructural autoradiographic study of blast cells in the mouse thymus. Interest for radioleukemia research.

Ultrastructural autoradiographic studies of mouse thymic blast cells after H3 Tdr injection show that their fine nuclear structure is related to their position in the cell cycle. The variations in the composition of the subcapsular blast cell population during radiation-induced leukemogenesis indicate kinetic changes in thymic lymphopoiesis, which are probably due to the oncogenic process.     

Functional study of the rat olfactory bulb by a 14C-2-deoxyglucose autoradiographic technic]

The autoradiographic method has been used in the Rat to map active regions in the olfactory bulb after a pulse of 14C-2-deoxyglucose with electrical stimulation of the lateral olfactory tract. The highest optical densities were found at the external plexiform, mitral, internal plexiform and granular layers; the lowest was found in the glomerular layer.     

Autoradiographic study of the penetration of non-histone chromatin proteins into differentiating cells.

Attention has previously been drawn to a specific effect of NHCP on embryonic Pleurodeles cell differentiation. With a modified NHCP labelling technique, autoradiography has revealed a cytoplasmic concentration of labelled NHCP and has not revealed any difference between homospecific and heterospecific NHCP penetration.     

Intracellular protein degradation in mammalian cells: recent developments

In higher organisms, dietary proteins are broken down into amino acids within the digestive tract but outside the cells, which incorporate the resulting amino acids into their metabolism. However, under certain conditions, an organism loses more nitrogen than is assimilated in the diet. This additional loss was found in the past century to come from intracellular proteins and started an intensive research that produced an enormous expansion of the field and a dispersed literature. Therefore, our purpose is to provide an updated summary of the current knowledge on the proteolytic machinery involved in intracellular protein degradation and its physiological and pathological relevance, especially addressed to newcomers in the field who may find further details in more specialized reviews. However, even providing a general overview, this is an extremely wide field and, therefore, we mainly focus on mammalian cells, while other cells will be mentioned only for comparison purposes.     

A method for measuring apatite crystals in human dentine by high resolution transmission electron microscopy]

High resolution electron microscopy now makes it possible to use an original method for measuring biological apatite crystals. The crystals of intertubular sound dentine have an average width of 296 A (standard deviation: 37) and an average thickness of 32 A (standard deviation: 5). During the course of so-called arrested caries, crystals get twice as thick compared to those sound dentine, whereas their width remains unchanged.     

A combined histochemical and autoradiographic study of the distribution and maturation of peritoneal mast cells in the rat

Summary The relationship of mitotic activity and degree of cytological differentiation for mast cells of the peritoneal cavity of the rat was studied using combined autoradiographic and histochemical techniques. A mitotic pool of mast cells can be differentiated from a non-mitotic pool, the former containing cells with immature cytoplasmic differentiation and the latter with fully developed cytoplasmic histochemical properties.     

Protein farnesylation in mammalian cells: effects of farnesyltransferase inhibitors on cancer cells

Protein farnesylation, catalyzed by protein farnesyltransferase, plays important roles in the membrane association and protein-protein interaction of a number of eukaryotic proteins. Recent development of farnesyltransferase inhibitors (FTIs) has led to further insight into the biological significance of farnesylation in cancer cells. A number of reports point to the dramatic effects FTIs exert on cancer cells. In addition to inhibiting anchorage-independent growth, FTIs cause changes in the cell cycle either at the G1/S or at the G2/M phase. Furthermore, induction of apoptosis by FTIs has been reported. FTIs also affects the actin cytoskeleton and cell morphology. This review summarizes these reports and discusses implications for farnesylated proteins responsible for these FTI effects. Received 17 April 2001; received after revision 28 May 2001; accepted 28 May 2001     

Functional study of cultured bone cells]

Osseous cells in culture synthesize and excrete glycosaminoglycans, collagen and alkaline phosphatases, revealed by the classical histochemical reactions. Observation of the living cells iwth the polarizing microscope, after a five day-culture, reveals the presence of micro-crystals of mineral salts only at the level of cells and cellular groupings.