Showing papers by "French Institute of Health and Medical Research published in 1974"

Membrane associated particles: distribution in frog urinary bladder epithelium at rest and after oxytocin treatment.

Abstract: The fine structure of the plasmic membrane of the frog urinary bladder epithelium has been studied with a freeze-etching technique. The results reveal that the external face of the cytoplasmic leaflet (A face) of the apical membrane of epithelial cells is characterized by: 1) A markedly reduced number of membrane associated particles compared to the value observed on the A face of the lateral membranes of these cells. 2) The existence after oxytocin treatment of numerous spots of clustered particles.

Interactions of glucagon, gut glucagon, vasoactive intestinal polypeptide and secretin with liver and fat cell plasma membranes: binding to specific sites and stimulation of adenylate cyclase.

Abstract: To investigate the interactions of pancreatic glucagon, gut glucagon, Vasoactive Intestinal Polypeptide (VIP) and secretin with liver and fat, the binding of the peptides to specific sites and the stimulation of adenylate cyclase were studied in the plasma membrane fraction. Binding studies indicated that the receptor sites for pancreatic glucagon are clearly distinct from the sites for VIP and secretin in both tissues: unlabeled VIP and secretin did not affect the 125I-glucagon binding, and unlabeled glucagon was without effect on the 125I-VIP and I25I-secretin binding. In contrast, secretin and VIP appear to share a common binding site in both tissues: unlabeled secretins (natural and synthetic) were capable of displacing the (m)I-VIP and unlabeled VIP inhibited the binding of 125I-secretin. Gut glucagon inhibited the binding of 125I-glucagon as well as that of 125I-VIP and 125I-secretin in both tissues. In the 125I-glucagonbinding systems, the inhibitory effect of gut glucagon, which contrasts sharply ...

Source of the anti-Müllerian hormone synthesized by the fetal testis: Müllerian-inhibiting activity of fetal bovine Sertoli cells in tissue culture.

Abstract: Extract: In order to determine which tubular cells are responsible for the secretion of anti-mullerian hormone (AMH), a method which would yield a pure preparation of fetal Sertoli cells appeared to be desirable. In tissue cultures of postnatal testicular cells, germinal elements remain free-floating in the medium, whereas cells of nongerminal origin attach themselves to the surface of the culture vessel and form a monolayer. If, before cell dissociation, seminiferous tubules are isolated from interstitial tissue, the monolayer formed on the flasks plated with tubular cells is formed only by Sertoli cells. By applying this method to fetal calf testicular tissue, we have obtained separate cultures of fetal Sertoli and interstitial cells and tested mullerian-inhibiting activity. Tubular cells exhibited a pavement-like pattern, tended to form circular structures, and inhibited the rat fetal mullerian duct after transferral to organ culture conditions. Interstitial cells had a fibroblastic appearance in monolayers, and did not display mullerian-inhibiting activity. Speculation: Monolayers arising from the tubular and interstitial compartment of the calf fetal testis, respectively, have been established. As, in the postnatal testis, germ cells do not attach to the walls of culture vessels, it is speculated that the tubular monolayer is formed by Sertoli cells only. Their mullerian-inhibiting activity confirms our previous hypothesis that Sertoli cells are the source of the mullerian-inhibiting hormone.

Binding of interferon to gangliosides.

Abstract: RECENT evidence suggests that the antiviral action of interferon is triggered by interaction with the cellular membrane. Mouse interferon covalently bound to Sepharose beads (IF-Sepharose) retains its antiviral potency and only direct contact with these particles produces the antiviral effect1,2. Preincubation of mouse L cells with Phaseolus vulgaris phytohaemagglutinin (PHA) blocks interferon action3. The inhibitory action of PHA can be almost completely reversed by washing PHA-treated cells with fetuin, a glycoprotein of high affinity for this plant lectin3. These data suggest that membrane sites interacting with interferon are carbohydrate-containing molecules that bind to PHA, although other explanations for the inhibitory action of PHA based on nonspecific steric or charge effects might be possible. To substantiate further that glycoside-containing membrane components bind to interferon, we have investigated the effect of gangliosides on interferon binding and action.

Fiber organization at the posterior spinal cord‐rootlet junction in man

Abstract: The authors have carried out serial section analysis in an attempt to elucidate the fiber organization at the posterior spinal cord-rootlet junction in Man. In the peripheral segment of the rootlet, large and small caliber fibers have no particular organization. On the contrary, at the level of the spinal cord-rootlet junction, small caliber fibers are re-grouped in the ventro-lateral region, whilst the large fibers are central and dorso-medial. After consideration of published experimental data, which show that the small caliber fibers activate the nociceptive system, the authors have carried out in Man selective sections of the small fibers for antalgic reasons. These selective posterior rootlet sections - operation called selective posterior rhizidiotomy - result in an analgesia without suppression of tactile epicritic and conscious proprioceptive sensitivities.

Apparatus for the non-destructive examination of heterogeneous samples

Abstract: The present invention relates to an apparatus for the non-destructive examination of an heterogeneous sample by analysis of the Raman radiations scattered by the sample receiving an incident of monochromatic radiation of known frequency. The apparatus includes a source of monochromatic light, such as a laser beam, a monochromator for selecting and measuring the change in frequency of the Raman scattered or re-emitted radiations with respect to the frequency of the incident radiation, a radiation detector and an amplifier to amplify signals from the detector. The apparatus identifies each such re-emitted radiation by comparison with control samples or reference spectra. The invention enables selective mapping of the distribution of the polyatomic ions, crystals and molecules of the sample. Apparatus embodying the invention permits mapping, by micrographic images, of the components of geological samples, composite materials, plastic materials, biological samples, microscopic preparations and the like, by isolating in the Raman spectrum the radiations characterizing the components.

Interference of oral immunization with the intestinal absorption of heterologous albumin

Abstract: Rats were immunized with human serum albumin (HSA) by a single intragastric administration of 200 mg of HSA. Two weeks later their capacity to absorb a similar intragastric test dose of HSA was found to be greatly impaired, the concentrations of HSA in mesenteric venous serum having been reduced to 33 %, 25 % and 60 % of those in similarly tested but unprimed animals, respectively 1, 2 and 3 hours after the intragastric test dose. Rats given antigen (HSA) together with intestinal secretions from intragastric immunized rats also showed a striking decrease in intestinal absorption of a test dose, compared to controls given the antigen together with nonimmune intestinal secretions. From these data it is concluded that local immunization of the gut impairs its capacity to absorb the corresponding antigen, and that this effect is largely due to the failure to absorb antigen bound to secretory antibodies.

Transformation of Chick Embryo Neuroretinal Cells by Rous Sarcoma Virus in vitro: Induction of Cell Proliferation

Abstract: Neuroretinal cells from 7-day-old chick embryos are transformed and induced to proliferate after infection with Rous sarcoma virus in vitro. Susceptibility of neuroretinal cells to the virus is also dependent on the stage of development since infection of cells from 10-day-old embryos is uneffective.

Prostaglandin receptors in human and ovine adrenal glands: binding and stimulation of adenyl cyclase in subcellular preparations.

Abstract: The binding of3H prostaglandins (PGE1 and PGEM2) and the stimulation of adenyl cyclase through the action of PGE1 and PGE2 in subcellular preparations of human and ovine adrenal gland and on highly purified membranes were studied. Binding of prostaglandins is a specific phenomenon that is inhibited by prostaglandins only. Prostaglandins are bound to subcellular preparations with an affinity of 108M.−1 The stimulation of adenyl cyclase activity is detectable from 10−8M and reaches its maximum value at 3–10−6M. At their level of maximum stimulation the PGE1 and PGE2 prostaglandins have no additive effects, whereas maximum stimulatory concentrations of prostaglandins and ACTH do. These facts show that plasma membrane receptors for prostaglandins exist in the adrenal gland: they are common to prostaglandins PGE1and PGE2 but distinct from those of ACTH. (Endocrinology 95: 352, 1974)

Hormonal control of oestrogen receptor in uterus and receptivity for ovoimplantation in the rat

Abstract: THREE distinct states of the rat uterus with respect to ovoimplantation have been described. The prereceptive stage lasting from day 1 to day 4 is followed by receptivity during day 5; finally, during a postreceptive period from day 6 onwards, transferred mature blastocysts do not implant if implantation on day 5 has been prevented1. Analogous situations can be created in the castrated animal by treatment with a precise sequence of hormones; a minimum of 2 d of progesterone preparation is necessary to obtain, 18 h after the subsequent administration of a small dose of oestrogen the state of receptivity for ovoimplantation which will last for approximately 12 h. Again, a period during which the fertilised egg cannot implant will follow the time of receptivity, as shown by egg transfer experiments1.

Plasma tryptophan and 5-HT metabolism in the CNS of the newborn rat.

Abstract: —The relationships between plasma tryptophan and 5-HT metabolism in the CNS were studied in newborn rats and compared with adults. Both the concentration of free tryptophan in plasma and that of the amino-acid in brain were much higher immediately after birth than later on. Drugs such as salicylate and chlordiazepoxide, which increased brain tryptophan concentrations in adults by displacing the plasma amino acid bound to serum albumin, were ineffective in newborn rats: most of the amino acid being already free in their plasma. The study of 5-HT metabolism in brain stem slices revealed that the affinity of the uptake process for tryptophan was higher in newborn than in adult animals, whereas the reverse situation was observed for the enzyme complex involved in 5-HT synthesis (lower apparent Km in adults). In addition, the catabolism of newly synthesized 5-HT was more rapid in newborn than in adult tissues. Finally, the free state of tryptophan in plasma of newborn animals induced in brain both a high amino acid concentration and, in contrast to the situation observed in adults, a synthesis rate of 5-HT very near its maximal value.

The smooth endoplasmic reticulum and the retrograde and fast orthograde transport of horseradish peroxidase in the nigro-striato-nigral loop

Abstract: The axonal transport of horseradish peroxidase (HRP) has been investigated in the nigro-neostriato-nigral loop. The HRP moves bidirectionally, i.e. from cell bodies in the caudoputamen to their terminal arborization, mainly in pars reticulate, and from axon terminals in the neostriatum to their nigral cell bodies. Eighteen hours after the neostriatal injection of HRP both axon terminals and cell bodies in the substantia nigra are already labeled, indicating that the transport of HRP is associated with the fast phase of the axoplasmic flow.

Synaptic organization of the nucleus gracilis of the cat. Experimental identification of dorsal root fibers and cortical afferents

Abstract: The synaptic organization throughout the nucleus gracilis has been investigated in unoperated cats. Axon terminals of variable size can establish synaptic contacts with neuronal somata, dendritic processes, initial segment of axons or with other axon terminals at “complex synaptic arrangements.” Large boutons with rounded vesicles are regularly associated with smaller boutons containing flattened vesicles; the latter type of bouton forms frequently a double synapse being presynaptic to the large bouton and to the element postsynaptic to this (“complex synaptic arrangements”). Medium-sized to small axon terminals of the “isolated” type contain primarily either rounded or flattened vesicles. These boutons are surrounded by a thin glial process which also wraps the postsynaptic element, mostly represented by a small dendritic profile. The “isolated” type of bouton seems to be more abundant in the rostral than in the caudal part of the nucleus. In all unoperated control animals altered axons and axon terminals are present. They are enlarged and display hyperplasia and dilatation of tubular profiles of smooth endoplasmic reticulum as well as proliferation of microtubules and various aspects of mitochondrial degeneration. In cats sacrificed 48 hours after section of lumbo-sacral dorsal roots a high number of “dark” boutons are observed in various stages of degeneration. These terminals are identifiable with the large boutons containing rounded vesicles and postsynaptic to the smaller boutons with flattened vesicles. The morphology of dorsal root terminals in the nucleus gracilis is discussed in relation to that of primary afferent terminals in other central structures and to the functional aspects of axo-axonic contacts. The sensori-motor cortex was removed in another series of animals which were sacrificed after one to four days. As a consequence of such lesions cortical fiber terminals in the nucleus gracilis may undergo either the “dark” or the “light” type of degeneration. These terminals are of smaller size than those of primary afferents, they usually synapse on dendritic profiles of small diameter, are not involved in axo-axonic contacts and seem to contain rounded vesicles. Therefore they can be identified with at least some of the small and medium-sized boutons of the “isolated” type.

Are non-dividing cells present in ageing cell cultures?

Abstract: THE idea that an increased number of non-dividing cells accumulate during the growth decline of human embryonic fibroblasts (HEF) cultivated in vitro has been put forward1. This concept of a non-dividing fraction of cells seems to be widely accepted2,3, but no compelling evidence exists so far, to show that non-cycling cells exist in old cultures of human fibroblasts. On the contrary, it seems that most, if not all, the cells can divide up to the end of the lifespan of human diploid cell lines. What seems to take place, however, is an increased transit time and heterogeneity of cell cycles4,5.

Receptor-binding assay of chemically modified insulins

Abstract: The binding affinity for the insulin receptor was determined with a variety of insulin derivatives and compared to the biological activity in vitro and in vivo and to the physical properties of the derivatives. The relative binding affinity of each derivative was measured in a specific insulin-receptor binding system using mono 125I-insulin and purified plasma membranes of rat liver. Twenty one chemically modified insulins were investigated, including acetylinsulins, crosslinked insulin dimer and insulin trimer, and insulins with an A1-B1 or A1-B29 intra-molecular crosslink. The relative binding affinity corresponded to the relative biological potency in vitro for all of the derivatives studied. There was a good agreement between the activity in vitro and the physical properties as measured by circular dichroism spectroscopy with the acetylinsulins and with the crosslinked insulin monomer, dimer and trimer. In contrast, with most of the derivatives possessing an intra-molecular crosslink, the very reduced binding affinity (0.2–5.9%) and the comparably reduced biological potency in vitro opposed the moderate changes in physical properties. Biological activity was consistently higher in vivo than in vitro.

An Investigation of Progesterone Receptors in Guinea Pig Vagina, Uterine Cervix, Mammary Glands, Pituitary and Hypothalamus*

Abstract: Specific progesterone binding macromolecules were found in the cytosol of the vagina, the uterine cervix and the mammary glands of castrated, oestradiol primed guinea pigs. The concentration of these receptors was high enough in the vagina and the cervix to allow the study of their characteristics. They were similar to the uterine receptor in their sedimentation coefficient (µ6.5S), their affinity for progesterone (KA µ 5.IO8–1.109M–1), their steroid specificity and their sensitivity to SH-blocking reagents. In not primed with estrogen castrated animals, the vaginal and cervical receptors were present in markedly lower concentrations and their sedimentation coefficient was of about 4.5S. The low concentration of the receptor in the mammary glands in these nonlactating animals did not permit the study of its characteristics. No specific binding was found in the hypothalamus and pituitary cytosol after either in vitro incubation with 3H-progesterone (or 3H-20α-hydroxypregn-4-en-3-one) or in vivo injection o...

[Changes in acetylcholine level and electrophysiological response during continuous stimulation of the electric organ of Torpedo marmorata (author's transl)].

Abstract: Resume —Au cours d'une periode de stimulation, la reponse electrophysiologique de l'organe electrique evolue en trois phases successives: decroissance, palier, decroissance. Le taux d'acetylcholine (ACh) totale baisse durant la premiere decroissance. Il augmente pendant le palier, pouvant atteindre et meme depasser sa valeur initiale. Une nouvelle baisse de ce taux coincide avec la derniere phase decroissante. Ces premieres variations du taux d'ACh ne concernent que le compartiment libre’ ou disponible qui est defini dans le texte. Les correlations decrites entre l'evolution de la decharge et celles de l'ACh ont ete observees constamment dans differentes conditions de stimulation, in vivo et in vitro, aux frequences de 1, 5 et 10/s. Une reduction de la temperature abrege et abaisse le palier de la reponse electrophysiologique, elle diminue la remontee de l'ACh disponible. Les premieres variations de l'ACh disponible evoluent en fonction du temps selon un mode relativement independant de la frequence de stimulation entre 1 et 10/s. Apres une incubation en presence d'acetate 14C-1 qui est incorpore dans la moitie acetyl de l'ACh, le tissu est stimule au contact du precurseur hautement radioactif. Dans ces conditions, les premieres variations d'ACh disponible s'effectuent sans changement de sa radioactivite specifique: le taux du transmetteur et sa radioactiviteevoluent parallelement. L'ACh synthetisee pendant le palier doit par consequent provenir d'un compartiment en equilibre avec l'ACh disponible ou du mediateur recemment libere. Apres la deuxieme decroissance, la radioactivite specifique de l'ACh disponible s'eleve, traduisant l'epuisement du pool precurseur et l'incorporation de l'acetate tres radioactif present dans l'espace extracellulaire. A cette phase d'epuisement succede une utilisation de l'ACh vesiculaire stable, ou liee, qui semble alimenter le compartiment disponible. Le nombre des vesicules synaptiques comptees sur des micrographies electroniques peut alors diminuer. Si la stimulation est poursuivie encore plus longtemps, le nombre des vesicules retrouve ou meme depasse sa valeur initiale mais le taux d'ACh liee reste bas. Nous avons evalue la concentration de l'ACh dans les terminaisons nerveuses et celle de ses produits d'hydrolyse dans la fente synaptique. Cette derniere concentration, tres elevee apres un seul influx, pourrait etre un des elements essentiels du couplage entre la vitesse de synthese de l'ACh disponible et celle de son utilisation. Abstract —During a period of stimulation the electrophysiological response of the electric organ shows three successive phases: decrease, plateau and late decrease. The level of total acetylcholine (ACh) diminishes during the first decrease. It increases during the plateau phase, where it may reach or even exceed the initial value. A new diminution of the ACh level coincides with the last decreasing phase. The first changes in ACh only concern the ‘free’ or available compartment, which is defined in the text. The correlations between the changes of ACh and those of the electrophysiological discharge have been consistently observed under various conditions of stimulation, in vivo and in vitro, at frequencies of 1, 5 and 10/s. When the temperature is reduced, the plateau of the response becomes lower and shorter, and the corresponding increase in ACh is smaller. The time course of the first changes in the available ACh was not modified by the frequency of stimulation between 1 and 10/s. After an incubation with [1-14C]acetate, which is incorporated in the acetyl moiety of ACh, the tissue was stimulated in the presence of the highly radioactive precursor. Under these conditions, the first variations in the available ACh are not accompanied by any change in its specific radioactivity (RA.S), variations of the radioactive and non-radioactive transmitter being parallel. The ACh synthesized during the plateau should therefore originate either from a pool in equilibrium with the available ACh, or from the recently released transmitter. Following the second fall of the available ACh, its specific radioactivity increases indicating a greater incorporation of the highly radioactive acetate of the extracellular space in a diminished precursor pool. After this phase, bound (stable vesicular) ACh is utilized and appears to supply the available compartment. The number of synaptic vesicles counted in electron micrographs may diminish at this stage. If stimulation is still continued, the vesicles recover or even exceed their initial number whereas bound ACh remains at a low level. An estimate has been made of the concentration of ACh in nerve terminals and its hydrolysis products in the synaptic cleft. The latter concentration, very high after only one impulse, may be of importance for the coupling of the speed of synthesis and utilization of available ACh.

Human migrations and linkage disequilibrium ofHL-A system

Abstract: A migration with admixture of genes in two populations inducesHL-A linkage disequilibrium or Δ when gene frequencies in the two populations are dissimilar. Since theHL-A linkage disequilibrium disappears very slowly, this factor could be used to recognize some migrations. In the recent migration of American Negroes, a dilution of Caucasoid disequilibrium is noted. By the presence of Δ values, a study of possible migrations around the world is reported and a brief comparison with other methods of research into population origins is discussed in connection with the European ecosphere: a well-known expansion axis is found from East to West (probably due to the Indo-European migration), which ends with admixture with various local Western European populations. Another expansion of genes is noted from the North of Europe towards the Southwest.

Calcium-Binding Properties and ATPase Activities of Rat Liver Plasma Membranes

Abstract: Plasma membranes from rat liver purified according to the pro- cedure of Neville bind calcium ions by a concentration-dependent, saturable process with at least two classes of binding sites. The higher affinity sites bind 45 nmol calcium/mg membrane protein with a KD of 3 ptM. Adrenalectomy increases the number of the higher affinity sites and the corresponding KD. Plasma membranes exhibit a (Na+-K+)-independent-Mg2+-ATPase activity which is not activated by calcium between 0.1 /&M and 10 mM CaC12. Calcium can, with less efficiency, substitute for magnesium as a cofactor for the (Na+ - K+)-independent ATPase. Both Mg 2 + - and Ca 2 +-ATPase activities are identical with respect to pH dependence, nucleotide specificity and sensitivity to in- hibitors. But when calcium is substituted for magnesium, there is no detectable membrane phosphorylation from (y_3 2 P) ATP as it is found in the presence of magnesium. The existence of high affinity binding sites for calcium in liver plasma membranes is compatible with a regulatory role of this ion in membrane enzymic mechanisms or in hormone actions. Plasma membranes obtained by the procedure of Neville are devoid of any Ca2+-activated-Mg2+-ATPase ac- tivity indicating the absence of the classical energy-dependent calcium ion transport. These results would suggest that the overall calcium-extruding activity of the liver cell is mediated by a mechanism involving no direct ATP hydrolysis at the membrane level.