Publications
| Title | Abstract | Year Filter | PMID(sorted ascending) Filter |
|---|
| isolation and characterization of acylneuraminate cytidylyltransferase from frog liver. | frog liver (rana esculenta) is a rich source of acylneuraminate cytidylyltransferase. the soluble enzyme was purified 250-fold almost to purity with 25% yield and a specific activity of 9 mkat/kg protein (0.54 u/mg protein) using deae sephadex and sepharose 6b chromatography, followed by preparative polyacrylamide gel electrophoresis. the molecular weight of the cytidylyltransferase was determined to be 163 000 with the aid of sepharose 6b chromatography and gel electrophoresis, with or without ... | 1980 | 6253375 |
| ganglionic blocking effect of indomethacin and other prostaglandin synthetase inhibitors. | the effect of various prostaglandin (pg) synthetase inhibitors such as indomethacin, diclofenac, fenoprofen, niflumic acid and sulindac was studied on the isolated sympathetic ganglion of rana esculenta. it was found that all the tested drugs inhibited synaptic transmission, an effect related to the inhibition of pg synthetase. it has been suggested that pgf2a might be involved in the modulation of synaptic function in the frog sympathetic ganglion. | 1980 | 6258388 |
| conductance fluctuations from the inactivation process of sodium channels in myelinated nerve fibres. | 1. na currents and fluctuations of na currents were studied under voltage clamp in the same myelinated nerve fibres of rana esculenta at 13 degrees c. the results were used to test several kinetic models for the gating process of na channels.2. long voltage pulses, depolarizing the membrane by 16-48 mv from a hyperpolarizing holding level of - 28 mv, were applied in 4 sec intervals. the d.c. and a.c. components of the membrane current were recorded during the last 328 msec of the 473 msec pulses ... | 1980 | 6262498 |
| structure of the axolemma of frog myelinated nerve: relaxation experiments with a lipophilic probe ion. | asymmetrical displacement currents are measured in the absence and in the presence of the lipophilic anion dipicrylamine (dpa) in the extracellular solution of nerve fibers of the frog rana esculenta. dpa (30 nm--3 microm) enhances the current by a component that has the properties expected for a translocation current of dpa ion across the lipid membrane. analysis in terms of a single-barrier model yields the translocation rate constant (k), the total surface density of dpa absorbed to the membr ... | 1981 | 6264083 |
| the microscopical structure and quantitative changes of pituitary cell populations in frogs (rana esculenta l.) irradiated by ultraviolet light. | the percentage of cell populations of hypophysis pars distalis, their ultrastructure, degranulation phenomena and volume of cell nuclei easured by karyometry was examined in frogs, rana esculenta l. irradiated by uv light. the observed changes, reflecting alterations of the secretory activity were most prominent in b2 cells producing gonadotropic hormones and in b3 cells probably responsible for the secretion of acth. a concomitant increase of the number of chromophobic cells was observed. the o ... | 1980 | 6269309 |
| effect of theophylline and imidazole on cyclic amp and cyclic gmp levels in active sartorius muscle of rana esculenta. | 1981 | 6270702 | |
| fluctuation analysis of na+ channels modified by batrachotoxin in myelinated nerve. | (1) single myelinated nerve fibers of rana esculenta were treated with the steroidal alkaloid batrachotoxin, and na+ currents and na+-current fluctuations were measured near the resting potential under voltage-clamp conditions. between test pulses the fibres were held at hyperpolarizing membrane potentials. (2) the spectral density of na+-current fluctuations was fitted by the sum of a 1/f component and a lorentzian function. the time constant tau c = 1/(2 pi fc) obtained from the corner frequen ... | 1981 | 6271214 |
| microelectrode studies of the effect of lanthanum on the electrical potential and resistance of outer and inner cell membranes of isolated frog skin. | microelectrodes were used to investigate the effect of 0.5 mm mucosal lanthanum (la3+) on the intracellular potential and the resistance of outer and inner isolated frog skin (rana esculenta) cell membranes. under short-circuit conditions, the transapical membrane potential vsco (mean value = -65.4 +/- 3.2 mv, inside negative) hyperpolarized to -108.7 +/- 2.3 mv in control skins, after addition of the sodium blocker amiloride. current-voltage curves for the outer and inner membranes were constru ... | 1982 | 6281435 |
| the effect of internal barium on the k current of the node of ranvier. | voltage clamp experiments were performed on single myelinated nerve fibres of the frog rana esculenta to study the influence of internally applied ba on the potassium outward current ik. potassium currents of ba-treated fibres decay rapidly during 30 ms depolarizations of more than 60 mv. the time constant tau of decay and the steady state potassium current ikss are strongly voltage dependent. the equilibrium dissociation constant k of the ba-receptor complex decreases e-fold for a 39 mv change ... | 1982 | 6289249 |
| [role of the adenylate cyclase system in utilization of succinate by the frog gastric mucosa]. | interrelationship between the adenylate cyclase system state and utilization of succinate as a substrate of oxidation in mechanisms of hcl secretion by isolated gastric mucosa of frog rana esculenta was studied. the inhibition of the protein synthesis by cycloheximide rendered gastric mucosa insensitive to the activation of hcl secretion by histamine and succinate. a similar effect was exerted by cimetidine, a blocking agent for h2-receptors. the blockade could be prevented with dibutyryl-camp. ... | 1982 | 6293891 |
| [trigger function of cyclic amp in the initiation of hcl secretion by the frog gastric mucosa]. | histamine (0.3 mm) caused a rapid but transient increase in camp level prior to a rise in hcl secretion in the isolated gastric mucosa of frog rana esculenta. h2-receptor blocking agent cimetidine (0.01 mm) suppressed hcl secretion which had been preceded by a decrease in camp level. no statistically significant changes in cgmp content were found. dibutyryl camp imitated the effect of histamine. in frogs captured in spring, with a high level of hcl secretion and high content of camp, histamine e ... | 1982 | 6293892 |
| the effect of camp on the cell membrane potential and intracellular ion activities in proximal tubule of rana esculenta. | experiments were performed in proximal tubule of the isolated perfused frog kidney to evaluate peritubular cell membrane potentials (pdpt), and the intracellular ion activities of sodium (nai+), chloride (cli-) and potassium (ki+) under control conditions and following peritubular application of dibutyryl-cyclic amp (camp, 2 x 10(-4) mol x 1(-1)). conventional and ion-sensitive microelectrodes were applied to record continuously camp-induced changes of these parameters in individual proximal tub ... | 1983 | 6302634 |
| flurazepam: effects on sodium and potassium currents in myelinated nerve fibres. | the effect of flurazepam-hcl on single myelinated nerve fibres of the frog rana esculenta was investigated. flurazepam affected both na and k currents: 0.25 mm of the drug decreased the peak na inward current to about 50%. the initial increase and subsequent decay of the na current was slowed down by a factor of 1.5 independent of membrane potential. the drug induced a slow phase in the recovery from na inactivation and frequency dependence of the na current block. the k current rose at a normal ... | 1983 | 6309535 |
| contractile reaction of isolated frog aorta after x-irradiation. | the action of x-rays (50 kv, filtered by 0.3 mm al) on helical strip of frog aorta (rana esculenta) has been investigated. the isolated preparations have a stable basal tone and are radio-sensitive to x-rays which induce reversible, dose-dependent, contractile responses. after repeated irradiation tachyphylaxis appears. the threshold doses are about 250 rat 3 to 6 kr/min, antiadrenergic (phentolamine, propranolol), anticholinergic (atropin), antihistaminic (neo-bridal) and serotoninergic (deseri ... | 1983 | 6310830 |
| effects of physostigmine on the voltage dependent ionic conductances of skeletal muscle fibres. | the voltage dependent ionic conductances were studied by analysing the phase plane trajectories of action potentials evoked by electrical stimulation of the sartorius muscles of the frog (rana esculenta). the delayed outward potassium current was measured also under voltage clamp conditions on muscle fibres of either the frog (rana esculenta) or xenopus laevis. on analysing the effect of physostigmine decreasing the peak amplitude, the rate of both the rising and falling phases of the action pot ... | 1983 | 6316728 |
| effects of physostigmine on the excitation-contraction coupling of skeletal muscle fibres. | the effects of physostigmine on the electrophysiological properties of the surface membrane and on the different steps of excitation-contraction coupling were studied on the skeletal muscle of the frog (rana esculenta). on analysing the phase plane trajectories of electrically evoked action potentials it was found that, similarly to the previously described ph dependence of the depolarizing effect of the alkaloid [14], the physostigmine-induced inhibition of the voltage-dependent sodium and pota ... | 1983 | 6316729 |
| the sensitivity of apical na+ permeability in frog skin to hypertonic stress. | na+ transport across abdominal skins of the frog species rana esculenta and rana pipiens was analyzed by recording short-circuit current (isc), transepithelial conductance (gt), and the current noise generated by the random blockage of apical na+ channels by the diuretic, amiloride. specific na+ current (ina) and conductance (gna), as reflected by the amiloride-sensitive part of isc and gt, respectively, were markedly depressed after addition of some osmotically active substances, like sugars or ... | 1984 | 6326045 |
| cytotoxic effect of choline, abolished by furosemide, in the diluting segment of frog kidney. | previous observations suggest that luminal application of tetra-n-alkylammonium ions may impair ion transport in the amphibian diluting segment. to investigate this question conventional kcl-filled and cl- sensitive microelectrodes were applied in diluting segments of the isolated perfused kidney of rana esculenta to evaluate transepithelial electrical and chloride electrochemical (pdte, eclte) as well as peritubular cell membrane potential difference (pdpt), measured at static head conditions. ... | 1984 | 6332306 |
| [effect of glycerin removal on the electrical resistance of isolated muscle fiber in the frog]. | fibres isolated from iliofibularis muscles of the frog rana esculenta were studied under current-clamp conditions with a double sucrose-gap technique. an increase of membrane resistance in muscle fibres (rm) was demonstrated during the first 10-15 min of glycerol removal in k2so4 solution. after a 30 min treatment in glycerol-containing k2so4 rm was 1.40 +/- 0.12 k omega x x cm2. the transfer of muscles from the glycerol-k2so4 solution to an isotonic k2so4 solution resulted in a progressive incr ... | 1984 | 6332400 |
| cerebellar afferents in the frogs, rana esculenta and rana temporaria. | afferents to the cerebellum in frogs (rana esculenta, rana temporaria) were studied by use of retrograde transport of horseradish peroxidase. following injections restricted to the molecular layer of the cerebellum cell labelling was found in the contralateral inferior olive and the ventral portion of the caudal medullary raphe. injections involving the granular layer resulted in labelling in the ventral horn of the cervical spinal cord, the caudal spinal trigeminal nucleus, the nucleus caudalis ... | 1984 | 6332678 |
| effect of phlorizin on the action potential and voltage-dependent ionic conductances in frog skeletal muscle. | the effects of phlorizin on the action potential and voltage-dependent ionic conductances were investigated in frog (rana esculenta) sartorius muscles. in order to study the ionic currents, phase plane trajectories of the action potentials were analysed. as a consequence of lowering the overshoot by 19%, the amplitude of the action potential was decreased on the effect of phlorizin applied at a concentration of 2 mmol/l. the maximum rate of rise of the action potential (v +max) was reduced on th ... | 1984 | 6333779 |
| effects of chemical modification of carboxyl groups on the voltage-clamped nerve fiber of the frog. | voltage-clamped single nerve fibers of the frog rana esculenta were treated with the carboxyl group activating reagent n-ethoxy-carbonyl-2-ethoxy-1,2-dihydroquinoline (eedq) in the presence of different primary amines and without added amine. carboxyl groups form stable amide bonds with primary amines in the presence of eedq. eedq treatment reduced the sodium current considerably and irreversibly, regardless of the presence of a primary amine in the ringer's solution. the potassium current was a ... | 1984 | 6334164 |
| effect of various cations and anions on the action of tetrodotoxin and saxitoxin on frog myelinated nerve fibers. | the influence of mg2+, la3+, no-3, and scn- on the equilibrium effect of tetrodotoxin (ttx) and saxitoxin (stx) on single myelinated nerve fibres of the frog rana esculenta was studied under voltage clamp conditions. mg2+ and la3+ reduce the sodium permeability, shift the voltage dependence of the na permeability pna towards more positive potentials and reduce the effectiveness of ttx and stx. no-3 and scn- reduce the sodium permeability too, but shift the voltage dependence of pna towards more ... | 1984 | 6335243 |
| effects of prolactin and experimental handling on liver, fat body and ovary lipid contents and their daily variations in rana esculenta (l.). | three groups of females of r. esculenta were kept under constant temperature and photoperiod conditions (l:d = 12:12). one group consisted of intact frogs, while the remainder were given saline or prolactin (prl) injections 6 hours after light onset. after 5 days of such treatment examination was made every 6 hours over a 24-hour period of lipid content in the liver, fat bodies (fbs) and ovaries and the level and composition of plasma lipids. both the experimental handling and prl treatment caus ... | 2013 | 6335944 |
| premeiotic events and meiotic chromosome pairing. | there is practical difficulty in identifying when meiosis begins. moreover, because of contradictory definitions there is ambiguity and some confusion as to when, in terms of the cell cycle, premeiosis ends and meiosis begins. nevertheless, results for several organisms show clearly that meiotic chromosome behaviour is affected by premeiotic events and especially by events during the final premeiotic mitosis and/or premeiotic interphase. this review considers only premeiotic events which do (or ... | 1984 | 6400221 |
| [effect of ionophore a23187 on the response to adh in the ventral skin of rana esculenta]. | the addition of the ca++ ionophore a23187 (10 microm) to the inside solution of the frog skin induced a transient increase in the active na+ transport in frog skin (rana esculenta) which decayed to the control values 60 minutes after the addition. at the same time the skin resistance failed significantly; antidiuretic hormone addition resulted in no-more increase of the na+ active transport; the skin resistance remained unchanged. to further investigate the role of intracellular calcium on the s ... | 1983 | 6414490 |
| hydrosmotic effect of vasopressin in frog skin of rana esculenta: effect of calcium ionophore a23187. | 1984 | 6432007 | |
| effect of vasopressin on the permeability of nonelectrolytes across the skins of rana esculenta and bufo bufo. | 1984 | 6432008 | |
| seasonal testosterone profile and testicular responsiveness to pituitary factors and gonadotrophin releasing hormone during two different phases of the sexual cycle of the frog (rana esculenta). | plasma and testicular testosterone concentrations in the frog, rana esculenta, were studied by radioimmunoassay and showed similar seasonal fluctuations. the increase in testicular androgen during november preceded that occurring in the plasma by 2 months. pituitary products and gonadotrophin releasing hormone, and the responsiveness of the testis to these substances play an important role in determining the hormone profile. | 1984 | 6434683 |
| the cyclo-oxygenase pathway in the avascular heart of the frog, rana esculenta l. | a modification of vane's cascade is reported, allowing the superfusion bioassay of prostaglandin-like substances (pls) in the outflow of isolated and perfused heart of the frog rana esculenta l. using both this technique and radioimmunoassay determination, the cyclo-oxygenase pathway in perfused frog heart has been investigated. arachidonate (aa) (2-20 micrograms) injected into the perfusing fluid, was transformed by the heart into pls, as shown by the response of the bioassay tissues (rat stoma ... | 1984 | 6436138 |
| stimulatory effect of a gnrh agonist (buserelin) in in vitro and in vivo testosterone production by the frog (rana esculenta) testis. | the summary testicular effects of an agonistic analogue of gonadotropin-releasing hormone (buserelin, gnrha) have been studied in vitro and in vivo in the frog, rana esculenta. during 3 h incubation gnrha (8 x 10(-7) m) potentiated pituitary factors in stimulating testosterone production by minced testes in vitro. after 6 h of incubation 8 x 10(-7) m gnrha stimulated maximal testosterone output. testes of 10-day hypophysectomized animals did not show any gnrha effect in vitro. in vivo, a direct ... | 1984 | 6439581 |
| cellular ph and the adh-induced hydrosmotic response in different adh target epithelia. | the hydrosmotic response elicited by oxytocin in the frog skin epithelium (rana esculenta) was reversibly inhibited by 70% when the medium ph was reduced to 6.2 by co2 bubbling on the serosal side. on the contrary, the response to 8-bromo cyclic amp (8 br-camp) was not affected by medium acidification, even after corion removal. in other experiments intracellular ph was measured, employing the dimetyl-oxazolidine-dione distribution technique, in frog urinary bladder and the isolated frog skin ep ... | 1984 | 6441925 |
| comparison of the sarcoplasmic and myofibrillar proteins of twitch and tonic fibres of frog muscle (rana esculenta). | sarcoplasmic and myofibrillar proteins of a frog mixed muscle (distal cruralis bundle) were investigated and compared to their fast twitch muscle homologues. histochemical reactions revealed two populations of fibres in this muscle, differing from fast twitch fibres by the intensity of their myofibrillar atpase reaction and by their mitochondrial nadh dehydrogenase activity. the distribution of parvalbumins and ldh isoenzymes in the whole muscle showed some features of tonic muscle type. myosin ... | 1980 | 6447068 |
| atpase activity in rapidly activated skinned muscle fibres. | the atpase activity of single mechanically skinned fibres from semitendinosus muscle of rana esculenta was measured. the method was based on the fluorimetrically detected consumption of nadh inside the fibre. nadh breakdown is caused by the reaction of an atp regenerating system coupled to an nadh oxidising system. the time resolution was about 5 s. the initial rise in atpase activity was delayed when a fibre was activated by ca, and atpase activity reached its plateau at the same time as fibre ... | 1980 | 6448985 |
| light- and electron-microscopic demonstration of immunoreactive opsin in the pinealocytes of various vertebrates. | an antibody to opsin isolated from rod outer segments of the frog retina was applied in light- and electron-microscopic immunocytochemical studies to the pineal organ of various vertebrates (cyprinus carpio, carassius auratus, rana esculenta, emys orbicularis, pseudemys scripta elegans, lacerta agilis and viridis. gallus domesticus, columba livia, melopsittacus undulatus, serinus canaria, taeniopyga punctata, didelphis virginiana, erinaceus roumanicus, myotis myotis, rabbit, rat, cat). | 1981 | 6458362 |
| oscillating repolarization in action potentials of frog sensory myelinated nerve fibres. | current and voltage clamp experiments were performed in single myelinated sensory nerve fibres of rana esculenta. the k current was blocked by external tetraethylammonium-chloride and internal cscl. negative prepotentials led to the formation of a plateau in the repolarization phase of the action potential, and further regenerative depolarizations emerged from this plateau. a three-state model for na inactivation based on voltage clamp data was sufficient to simulate these observations. | 1983 | 6602313 |
| neuroanatomical asymmetry in the telencephalic hemispheres of the frog rana esculenta. | the frog's brain postfixed with osmium tetroxide and stained with uranyl acetate was examined for asymmetries. examination with the light microscope of serial semithin sections of the telencephalon revealed a nucleus of dark cells located in the lateral cortex of only the left hemisphere in a region close to the 'porcion arqueada' of pedro ramón y cajal. electron microscopy of ultrathin sections suggests that the cells of this asymmetric nucleus are neurons with a coarse cytoplasmic texture, whe ... | 1983 | 6603598 |
| [effect of n-ethylmaleimide, introduced in to the serous fluid, on the active transport of sodium through the skin of rana esculenta]. | an sh reactive agent, n-ethylmaleimide (nem), if introduced in the serosal bath (10(-4) m), stimulates the short circuit current (scc) across the frog skin. this effect is due to an increase of na active transport, because is inhibited by ouabain (10(-4) m). a stimulatory action on cl- or hco3- secretion can be ruled out because the rise in scc occurs also in the absence of cl- or hco3-. it is known that nem inhibits the adh action by forming covalent bounds with sh groups of adh membrane recept ... | 1983 | 6603855 |
| observations on the blood-testis barrier in a frog and a salamander. | a blood-testis barrier has been demonstrated in a frog, rana esculenta, and in a salamander, salamandra salamandra, using lanthanum as an electron-dense marker during fixation. the tracer penetrates the interstices between somatic follicle or sertoli cells and germ cells in regions of the testis containing spermatogonia and spermatocytes, up to the level of punctate tight junctions. the latter can be localized between the somatic cells that line seminiferous units containing spermatids and matur ... | 1983 | 6603909 |
| photoreceptor layer composition in the retina of the frog (rana esculenta). | retinas of rana esculenta frogs were studied by light and electron microscopy in order to establish the photoreceptor layer composition. we found 56% red rods, 9% green rods, 19% single cones, and 16% double cones. this work provides the morphological basis for electrophysiological investigations concerning the mass receptor potential of isolated rana esculenta retinas. | 1983 | 6603996 |
| calcite in the statoconia of amphibians: a detailed analysis in the frog rana esculenta. | the otoconia of amphibia, especially of the frog rana esculenta, were studied by x-ray diffraction and scanning electron microscopy (sem). the sem studies showed that the membranous labyrinth of amphibia contains two populations of crystals, which can easily be distinguished by their forms. the x-ray diffraction data indicated that these two populations consist of calcite and aragonite; the endolymphatic sac, the saccule and the lagena contain aragonite, whereas calcite is only found in the otol ... | 1983 | 6604580 |
| glucocorticoid receptor of frog (rana esculenta) liver. | the presence of a glucocorticoid soluble receptor is demonstrated in frog liver cytosol. the kinetic characterization of frog liver cytosolic receptor for glucocorticoids is reported and its steroid specificity assessed. results indicate a gross similarity between frog liver and mammalian glucocorticoid receptor, being a major difference the reduced binding capacity. | 1983 | 6604613 |
| [influence of environmental factors on skin concentrations of bradykinin in rana esculenta]. | 1983 | 6604661 | |
| development of na inactivation in motor and sensory myelinated nerve fibres of rana esculenta. | development of na permeability inactivation was investigated in myelinated motor (n = 12) and sensory (n = 12) nerve fibres of rana esculenta at 20 degrees c. the k currents were blocked by 10 mm tetraethylammonium chloride, added to the superfusing solution. additionally, in 4 fibres of each group internal cscl was applied by diffusion from the cut internodes. development of na inactivation was approximated by the sum of two exponentials. the time constants of the fast and slow inactivation pha ... | 1983 | 6604901 |
| experimental analysis of lens-forming competence of cornea, iris and retina of rana esculenta larvae. | 1983 | 6608200 | |
| seasonal plasma sex steroid levels in the female rana esculenta. | seasonal plasma progesterone, androstenedione, estrone, and 17 beta-estradiol concentrations in the female rana esculenta were determined by radioimmunoassay during the 1979 and 1981 seasons. plasma levels of these steroids were highest just before the first ovulatory wave in spring and lowest after the breeding season. in the 1979 season (during the 1981 season hormones were not assayed in january, november, and december) progesterone, androstenedione, and estradiol levels showed another peak i ... | 1984 | 6609099 |
| [annual growth of the ovary in a population of rana esculenta living in localities with different climates]. | 1984 | 6609417 | |
| matrix area activity in the regenerating optic tectum of rana esculenta. | after keeping specimens of rana esculenta at 4 degrees c for 24 hrs., the authors removed a plug of right optic tectum. thirty days later they injected 6-h3 thymidine and on the 200th day after surgery sacrificed the animals. with this technique it is possible to show the high regenerative capacity of the optic tectum; in fact, it is possible to observe reconstruction of the typical cellular and fibre layers of the removed nervous area. the origin of the cellular elements which supported this re ... | 1984 | 6609493 |
| cyclic renewal of whole pineal photoreceptor outer segments. | in the light-sensitive epiphysis cerebri of adult frogs (rana esculenta) adapted in summer to an artificial long day (l:d = 17:7; l = 90 lx at 2,300 degrees k; controlled temperature of 8 degrees c) outer segments of cone-like pineal photoreceptor cells exhibit a cyclic and complete renewal. shortly after 'lights off' inner segments protruding into the pineal lumen bear exclusively bulbous cilia of the sensory type. considering these results, concepts dealing with different types of sensory pine ... | 1984 | 6610149 |
| plasma sex hormones and post-reproductive period in the green frog, rana esculenta complex. | the plasmatic profiles of androgens, estradiol, and progesterone, together with gonads and ssc modifications, have been followed, throughout the post-reproductive period in two rana esculenta populations, inhabiting, respectively, a mountain pond (colfiorito) and a sea level lagoon (lesina). testosterone and progesterone progressively decrease in the blood until july, while estradiol shows, in both sexes, an increase in the same month. testosterone depletion accounts for thumb pad atrophy in the ... | 1984 | 6610601 |
| microperoxisomes and catalase peroxidatic activity in the pancreas of two amphibian species (salamandra salamandra l. and rana esculenta l.). | the fine structure of microperoxisomes (anucleoid peroxisomes) and catalase peroxidatic activity in salamander and frog pancreas have been investigated following glutaraldehyde fixation and incubation in a modified novikoff-goldfischer alkaline dab-medium. reactive microperoxisomes ranging in diameter from 0.16 to 0.76 micrometer were identified in both exocrine (acinar and ductular centro-acinar cells) and insular (b-, a-, d-cells) pancreatic tissue, as well as in the nerve fibers and endings. ... | 1980 | 6776774 |
| vasoactive intestinal polypeptide (vip)-like immunoreactivity in anuran intestine. | immunocytochemical and radioimmunological techniques with region specific antisera have been used to identify a vasoactive intestinal polypeptide-like material in the anuran intestine. seven species of anura were investigated: bombina bombina, alytes obstetricans, rana temporaria, rana esculenta, hyla arborea, hyla crepitans and bufo bufo. in five of the species (a. obstetricans, r. temporaria, h. arborea, h. crepitans and b. bufo) vasoactive intestinal polypeptide-like immunoreactive mucosal en ... | 1981 | 6784927 |
| the process for the activation of frog epidermis pro-tyrosinase. | 1. purified pro-tyrosinase from epidermis of the frog rana esculenta ridibunda can be activated in vitro by several proteinases (trypsin, alpha-chymotrypsin, pronase) and by light. 2. both pro-tyrosinase and tyrosinase are composed of a single type of subunit having pi 7.2 and approximate molecular weights 68000 and 62000 respectively. a peptide of low molecular weight is released as a consequence of the proteolytic activation. pro-tyrosinase and tyrosinase have different quaternary structures, ... | 1982 | 6814426 |
| activation of the efferent system in the isolated frog labyrinth: effects on the afferent epsps and spike discharge recorded from single fibres of the posterior nerve. | intra-axonal recordings were obtained from single afferent fibres of the posterior nerve in the isolated labyrinth of the frog (rana esculenta). epsps and spike discharge were recorded both at rest and during rotatory stimulation of the canal. electrical stimulation of either the distal end of the cut posterior nerve or of the central stumps of the anterior-horizontal nerves elicited a frequency-dependent inhibitory effect on the afferent discharge arising from the posterior canal. denervation e ... | 1980 | 6965463 |
| amino-terminal amino acid sequences and the evolution of frog (rana esculenta) trypsin and chymotrypsin. | 1980 | 6965480 | |
| extrahypothalamic peptidergic neurosecretion. ii. neurosecretion in the subfornical organ of rana esculenta l. | in the subfornical organ of rana esculenta, three basic structural elements can be demonstrated by light microscopic and immunohistological techniques used for the demonstration of products of the neurosecretory system. these elements are: (i) neurones and their processes, which the constituents of the subfornical organ proper, (ii) afferent axons of the preoptic nucleus, and (iii) subependymal cells with coarse processes. the vesicular inclusions of the two former structures correspond to the n ... | 1980 | 6965886 |
| myelinated dendrites in the spinal cord of frogs (rana esculenta). | myelinated dendrites--probably of motoneurons--were found in the spinal cord of the frog. it is assumed that the myelin sheath, by increasing the membrane resistance, improves the function of the dendrite as a cable. | 1980 | 6966143 |
| effect of temperature and light on the production of androgens in the male rana esculenta. | the present data show that experimentally-controlled environmental variables (light and temperature) can alter circulating androgen levels in the male green frog, rana esculenta, treated in different phases of the testicular cycle. | 1980 | 6966229 |
| the eggs of european water frogs (rana esculenta complex) and their hybrids. | 1980 | 6966587 | |
| intracellular potassium activity in epithelial cells of frog fundic gastric mucosa. | microelectrodes were used to measure membrane potential and intracellular potassium activity in surface epithelial cells (sec) of frog (rana esculenta) fundic gastric mucosa in vitro. separate measurements were carried out by applying fine-tipped, single barrelled, kcl filled non-selective electrodes and liquid k+ -selective electrodes. membrane potentials with respect to the mucosal and serosal surfaces, measured with non-selective electrodes, were -54.5 +/- 1.0 s.e mv (n = 59) and -73.0 +/- 1. ... | 1980 | 6966792 |
| androgen receptor in the thumb pad of rana esculenta: dynamic aspects. | the androgen receptor (dissociation constant, 6 x 10(-9) mol/l) present in the 105 000 g cytosol fraction of the thumb pad of rana esculenta is hormone dependent. the number of testosterone binding sites decreased in the absence of the testes and in long-term castrated animals (75 days) became undetectable. administration of testosterone (50 ng) induced the replenishment of the cytophasmic androgen receptor; its concentration also varied during the annual reproductive cycle. | 1980 | 6967507 |
| long-term persistence, after eye-removal, of unmyelinated fibres in the frog visual pathway. | long-term fibre degeneration was studied in the optic nerve, and the optic tectum in rana esculenta using the cobalt filling technique. myelinated retinal fibres disappeared within 26 days. a number of unmyelinated axons, however, persisted during the experimental period (91 days after eye removal). it was concluded that myelinated fibres degenerate considerably faster than unmyelinated ones in the frog visual system. | 1980 | 6967755 |
| large granular vesicles in the frog spinal cord. | two types of large granular vesicles have been demonstrated in the spinal cord of the frog rana esculenta. each type is contained in different fibres located in the neuropil of the ventral horn. the two types of vesicles differ in their diameter and quantity, in the smoothness of their limiting membrane and the electron density of their core. the possibility that they contain peptides is discussed. | 1980 | 6968274 |
| nonelectrolyte fluxes across gastric mucosa in relation to gastric stimulation. is gastric juice secreted by osmosis or exocytosis? | the effects of histamine and thiocyanate, added to the serosal bathing solution, on unidirectional fluxes of some nonelectrolytes (thiourea, methylated thiourea derivates, mannitol), and on h+, pepsinogen and mucous secretion were investigated in frog (rana esculenta) fundic gastric mucosa. histamine (10(-4) m) increases significantly the outfluxes (serosa to mucosa fluxes) of only thiourea and its derivates (but not mannitol) and the stimulation is the greater the more lipidsoluble the nonelect ... | 1980 | 6968890 |
| effects of anesthesia, surgical manipulation and dehydration on the nucleic acid and protein content of the pituitary and hypothalamus of the frog. | various types of stress, chemical or surgical, have a negative influence on the protein and rna content of the hypothalamo-hypophyseal system of rana esculenta. a degree of recovery occurs in these tissues 24 h after ms222 anaesthesia and laparotomy. decapitation is apparently the most suitable method of sacrificing the animals. | 1980 | 6969186 |
| the effect of thyroxine and triiodothyronine on glucose-6-phosphate and 6-phosphogluconate dehydrogenase activity in liver and fat body of the frog rana esculenta. | 1980 | 6969206 | |
| kinetics of ionic transport across frog skin: two concentration-dependent processes. | sodium and chloride influxes across the nonshort-circuited isolated skin of rana esculenta were measured at widely varying external ionic concentrations. the curve describing sodium transport has two michaelis-menten components linked at an inflection point occurring at an external sodium concentration of about 7 meq. chloride transport can also be represented by two saturating components. a possible explanation of these kinetics is discussed. at sodium concentrations lower than 4 meq it is poss ... | 1980 | 6969316 |
| transmitters and/or metal atoms in muscle mechanics. | acetylcholine in concentrations of 10-5, 2 x 10-5, 5 x 10-5 and 10-4 in normal ringer's solution causes contracture of different muscles of rana esculenta. the similar effect brought about by kcl solution does not necessarily mean the same basic process leading to similar changes in muscle mechanics. experiments made on many particular questions of muscle mechanics will possibly clarify the real role of single factors (e.g. transmitters, kations, anions, acids, alkalis. atp, heat etc.) changing ... | 1980 | 6969510 |
| bound potassium in muscle ii. | experiments were performed to decide between the alternatives a) the ionized k+ is in a dissolved state in the muscle water, or b) a part of the muscle potassium is in a "bound' state. sartorius muscles of rana esculenta were put into glicerol for about one hour at 0-2 degrees c. most of muscle water came out, but most of muscle potassium remained in the muscles. in contrast to this: from muscle in heat rigor more potassium was released due to glicerol treating than from the intact ones. 1. supp ... | 1980 | 6969511 |
| k and ca in muscle mechanics, ii. k-contracture. | k-rich solution, the isotony of which corresponds to normal ringer's solution, was used in our experiments: 4.59 g kcl + 40.5 g saccharose, 1000 ml bidistilled water. freshly prepared living muscles of rana esculenta (m. sartorius, m. iliofibularis, m. peroneus, m. tibialis, m. gastrocnemius, m. semimembranosus) got into k-contracture in this solution, but they relaxed within some minutes. in muscles of dead frog (which canno tbe stimulated with 110 v a.c.) the k-rich solution did not elicit con ... | 1980 | 6969512 |
| [evidence of morphological modifications induced by theophylline in the urinary bladder epithelium of rana esculenta]. | this preliminary work concerns the morpho-functional action induced by theophylline on bladder epithelium. the epithelium treated with theophylline shows important structural variations. the whole tissue thickness appears reduced with cell disposed in monostratified layer. they show a light grade of swelling with nucleus and cytoplasm less evident and boundary less marked. it is important to note that the permeability of the epithelium does not appear modified. | 1980 | 6969597 |
| facilitated transport of urea across the baso-lateral membrane of the urinary bladder of rana esculenta. | 1981 | 6970704 | |
| cross bridge slippage in skinned frog muscle fibres. | mechanically skinned single fibres of the semitendinosus muscles of rana esculenta were investigated at ca. 4 degrees c. the fibres were activated by a ca2+ jump technique, which allowed the development of a steady isometric tension within several seconds of entering a calcium rich solution at 4 degrees c. sequences of length changes of different duration and amplitude were applied to the fibre. it could be demonstrated that the fibre behaved as a hookean spring in the case of small amplitude le ... | 1980 | 6971661 |
| preventive effect of some substances on experimental oxalic calculogenesis in the frog. | rana esculenta tadpoles that are fed spinach develop an oxalic calculogenesis. the addition of cholestyramine, orthophosphate, citrate, allopurinol and tungstate to the tank water prevented calculi formation while succinimide, magnesium oxide, hydrochlorothiazide and tetracycline were ineffective. methylene blue proved lethal to tadpoles, and its anti-lithogenic activity could not be assessed. these findings, except for the non-effectiveness of magnesium oxide, are in agreement with both the the ... | 1981 | 6972114 |
| viral particles in the hepatocytes of rana esculenta (l). | the hepatocytes of rana esculenta exhibit hexagonal, probably icosahedral, viral particles disseminated in the cytoplasm among cellular organelles (mitochondria, cisternae of the endoplasmic reticulum, golgi complex). the particles consist of an electron-dense core (nucleoid) and a less electron-dense envelope (capsid). empty capsids (without nucleoid) or semilunar capsid fragments can be sometimes observed. the virus seems to be a cytoplasmic one, as it has not been found in the nucleus of hepa ... | 2013 | 6972664 |
| role of eyes and pineal gland in melanophore response in the green frog. rana esculenta. | the studies suggest that complete inhibition of msh liberation from the pars intermedia is brought about in response to the receipt of photic cues through the eyes and, possibly, by the pineal gland. the punctuate condition of epidermal melanophores is brought about by the inhibition of msh liberation alone, whereas the punctuate condition of dermal melanophores is brought about by the inhibition of msh liberation and the liberation of melanin aggregating substance from the pineal gland in respo ... | 1981 | 6973295 |
| increased charge displacement in the membrane of myelinated nerve at reduced extracellular ph. | asymmetry currents were measured in nodes of myelinated nerve fibers from rana esculenta at extracellular ph values of 5.2, 7.0, and 8.1 by averaging the currents during and after 1-ms depolarizing and hyperpolarizing voltage pulses. the charge displacement in the nodal membrane was obtained by numerical integration of the asymmetry currents. lowering the ph from 7.0 to 5.2 significantly slows down the kinetics of the fast charge displacement during depolarization but hardly affects the kinetics ... | 1980 | 6973369 |
| potassium currents and conductance. comparison between motor and sensory myelinated fibers. | the potassium conductance system of sensory and motor fibers from the frog rana esculenta were studied and compared by means of the voltage clamp. the potassium ion accumulation was first estimated from the currents and reversal potentials within the framework of both a three-compartment model and diffusion-in-an-unstirred-layer model. the potassium conductance parameters were then computed using the measured currents and corrected ionic driving forces. it was found that the potassium accumulati ... | 1980 | 6973371 |
| [cytological study on neuronal lipofuscin in the cns of the rana esculenta]. | neuronal lipofuscin has been found in adult rana e., and in tadpoles at the larval stage with external gills, larvae with internal gills and front legs, and larvae with front and back legs. the lipofuscin granules were positive at many histochemical tests and they had an autofluorescence at 450-470 nm the aa. plan to better define the ultrastructural characteristics and the anatomotopographic localization of the lipofuscin observed in future electron microscope studies. | 1981 | 6973998 |
| a three-state model for inactivation of sodium permeability. | the inactivation of na+ permeability in single myelinated motor nerve fibres of rana esculenta was investigated under voltage and current clamp conditions at 20 degrees c in ringer's solution and under blocked k+ currents. development of inactivation and its recovery was described by two potential-dependent time constants: the smaller time constant followed the usual bell-shaped function of membrane potential, whereas the larger one was monotone-increasing with more negative potentials. several ... | 1981 | 6974005 |
| premeiotic genome exclusion during oogenesis in the common edible frog, rana esculenta. | 1981 | 6974310 | |
| [mechanical parameters and cyclic nucleotides in the anaerobic fatigue of rana esculenta (author's transl)]. | 1981 | 6974390 | |
| the effect of laser irradiation on the frog pineal. | the frog pineal is a functional photoreceptor with probable endocrine capabilities. continuous wave laser radiation at 514.5 nanometers for 300 sec at 200 mw, as focused on the pineal of the intact frog rana esculenta to study the functional role of this structure. the investigation was carried out on 80 male specimens - 40 of which were controls - in light and in dark experimental conditions - during the months of march, july and november. the ratio gonad weight/body weight was used to measure ... | 1981 | 6974440 |
| mapping studies of the tectal representation of the frog binocular visual field. a problem of methodology. | using the classical mapping technique, the spatio-tectal visual organization in frogs (rana esculenta) was investigated taking special interest in the previously described existence of a "systematic disparity" between the two monocular receptive fields of rostral binocular tectal points. the existence of such a disparity was extended to the whole binocular visual field and its sign (crossed or uncrossed disparity) was studied both in paralyzed and anesthetized animals. it was proved however that ... | 1981 | 6974649 |
| chromosome banding in amphibia. vi. brdu-replication patterns in anura and demonstration of xx/xy sex chromosomes in rana esculenta. | a modified brdu-hoechst-giemsa technique permitted the demonstration of easily reproducible replication patterns in the somatic chromosomes of amphibia. these banding patterns allow for the first time a precise identification of all chromosomes and the analysis of the patterns of replication in the various stages of s-phase in amphibia. several possibilities for the use of this technique were demonstrated on three frog species of the family ranidae, all differing greatly in their dna-content. wi ... | 1981 | 6975199 |
| the rnase-rnase inhibitor system in the liver of the frog rana esculenta: subcellular distribution and differential binding of inhibitor with multiple rnases. | the aim of our work was to investigate the biological basis of the existence of multiple alkaline rnases in the rana esculenta liver with respect to formation of a rnase-rnase inhibitor complex (latent rnase). subcellular distribution indicated that most of the alkaline rnase activity appeared in the high-speed supernatant and mainly in a latent form bound to an endogenous inhibitor. this rnase-rnase inhibitor complex was isolated, the bound rnase activity was released and found to correspond to ... | 2006 | 6975551 |
| vascular arrangement in the oral mucosa of rana esculenta. scanning electron microscopy of corrosion casts. | corrosion casts of the blood vessels in the oral mucosa of rana esculenta were examined by the scanning electron microscope. special attention was paid to the palatine capillaries characterized by numerous blind diverticula. microanatomy and topography of these peculiar vessels suggests their involvement in gas exchange. the diverticula of the capillaries visible in the casts in form of nodules of various shape and size were examined in detail. | 1981 | 6975610 |
| [metamorphosis of hyla arborea and of rana esculenta in conditions of environmental pollution: a biostatistical study]. | an extention to the largest possible numbers of animal species is a basic requirement when damages induced by pollutants are studies with a specific purpose of defining the concentrations of pollutants compatible with the conservation of the biochemical system. animals should be bred in standard conditions, and the natural habitat is to be reproduced in the laboratory. the studies should also be planned favoring these statistical elaborations which are suitable of application also in case of int ... | 1981 | 6976178 |
| extrajunctional spread of acetylcholine depolarization on frog skeletal muscle membrane. | 1. the extrajunctional spread of end-plate depolarization induced by acetyl) choline (ach) applied in the bathing solution was studied on frog (rana esculenta-skeletal muscle fibers. 2. the characteristics of this spread were determined on sartorius muscles mounted in a chamber where the end-plate free pelvic part was separated by a rubber membrane from the end-plate containing tibial one. there was no change in membrane potential if ach was applied selectively on the pelvic part, even at a conc ... | 1981 | 6977258 |
| third ventricle suprachoroidal cells. | using transmission electron microscopy two types of cells on the choroid plexus of the third ventricle of the frog rana esculenta have been located. they lie on the microvilli and cilia of the choroid epithelium. their free surface is in contact with the cerebrospinal fluid. one type, kolmer-like, has large, dense bodies in its cytoplasm. the cytoplasm of the other type is completely filled by large, ovoidal structures which have a limiting membrane and a polymorphic filamentous content. their f ... | 1982 | 6977279 |
| effect of acetylcholine on ion transport in the frog skeletal muscle. | 1. the effect of acetylcholine (ach) on the ion transport of frog (rana esculenta) sartorius muscles was studied. ach was applied in bathing solution, na influx and k efflux were measured using 24na and 42k isotopes. 2. na influx of sartorius muscles was increased by 1 mmol/1 ach 2-10 fold depending on the experimental arrangement. the increase was greater if na influx was measured at the beginning of ach depolarization. during ach treatment the na influx took about the same time course as the d ... | 1981 | 6978595 |
| [the nature of urea transport across the skin of of rana esculenta]. | in several epithelial tissues such as toad bladder, gallbladder and human red cells, it has been established that urea movement implies a phloretin sensitive mediated transport. in the skin of the toad bufo viridis also it has been described an active transport of urea. our data, obtained on the frog skin seem to demonstrate the existence of some specific mechanism for urea transport towards the inside solution. in fact, two molecules having the some molecular diameter, such as urea and thiourea ... | 1982 | 6980654 |
| the chemoreceptor surface of the taste organ in the frog rana esculenta. a freeze-fracture analysis. | the epithelial surface of the taste disc on the fungiform papillae of the frog was studied by means of freeze-fracture and conventional electron microscopy. the plasma membrane of the apical process of taste receptor cells was found to exhibit a uniform population of 10-nm intramembrane particles on its fracture face p in a density of 1,000-1,800/micrometers2. in contrast to intramembrane particles in mucous cells or in other regions of the plasma membrane, these particles were observed to protr ... | 1982 | 6980710 |
| uptake of 6-h3 thymidine in the normal and regenerating cns of rana esculenta. | 1982 | 6981263 | |
| studies on light-sensitive units in the deep mesencephalon of blinded frogs. | unit responses susceptible to light stimulation of a small area on the frog's head were recorded in the deep encephalon of blinded specimens of rana esculenta. the responses consisted of a spike discharge upon illumination. using a threshold criterion the dark adaptation curves showed two parts, separated by a kink, the final dark threshold being complete after 20-30 min in darkness. using a threshold criterion the spectral sensitivity curves under dark adapted conditions were broad with a peak ... | 1982 | 6981880 |
| variations in the vitellogenin titre during the reproductive cycle of rana esculenta l. | 1. vitellogenin titre has been measured by rocket immunoelectrophoresis in specimens of rana esculenta l. caught at three different locations in southern italy. 2. variations in the serum level of vitellogenin are temporally related to ovarian growth during the reproductive cycle. 3. with the exception of the fl population, vitellogenin titre is low at spawning time but increases prior to ovarian recovery. 4. it eventually levels off, or undergoes a slight decline during winter, when the ovary i ... | 1982 | 6982149 |
| on 4-hydroxyphenylpyruvate dioxygenase of adult frog liver. | 1. it has been reported that 4-hydroxyphenylpyruvate dioxygenase (ec 1.13.11.27) activity in the liver from rana esculenta is present only after autolysis of trypsin digestion, which releases a heat-and acid-stable inhibitor of low molecular mass. 2. attempts to demonstrate similar effects with the liver enzyme from adult rana pipiens were unsuccessful. trypsin had only an inhibitory effect on the enzyme activity in crude extracts. 3. both untreated and trypsin-treated enzyme had a molecular mas ... | 1982 | 6982150 |
| effects of gonadal hormones on the lipid contents of the frog rana esculenta. | 1982 | 6982176 | |
| morphological and biochemical variations in the skin of rana esculenta during the annual cycle. | 1982 | 6982190 | |
| recurrent depression of postsynaptic responses in the frog motoneurons at low temperature. | recurrent depression of responses evoked in motoneurons by sciatic nerve volleys was studied at 1-3 degrees c body temperature in rana esculenta. gross recordings from the ventral root axons and intracellular recordings from the motoneurons were made. in accord previous data obtained from the same species using the same techniques at room temperature, recurrent volleys depressed the responses of motoneurons to sciatic nerve impulses also at low temperature. the latency and duration of the depres ... | 1981 | 6982594 |