Showing papers by "Radboud University Nijmegen published in 1972"
TL;DR: Plasma membranes have been isolated from calf eye lens fibre cells and the purified fraction is characterized by the occurrence of a large number of junctional complexes.
161 citations
TL;DR: Quasi-intracellular recordings from neurons in the lateral geniculate nucleus of the cat suggest, that the excitatory input of a geniculates neuron is originating from one single optic tract fibre.
Abstract: 1.
Quasi-intracellular recordings from neurons in the lateral geniculate nucleus of the cat have been made. From these recordings the excitatory input of these neurons could be determined.
2.
The experiments suggest, that the excitatory input of a geniculate neuron is originating from one single optic tract fibre.
3.
The experiments were performed on non-anaesthetized paralyzed cats which showed different levels of alertness such as sleep, drowsiness and wakefulness. During these different levels the input of the geniculate neurons remains constant but the output varies considerable. Thetransfer ratio, defined as the ratio between the spike frequency (output) and the EPSP frequency (input) of a neuron is high (0.9–1.0) during wakefulness and low (0.4–0.5) during sleep with intermediate values at intermediate states.
4.
The control of the transfer ratio is caused bychanging the amplitude of the EPSPs. During wakefulness nearly all EPSPs are large enough to reach the threshold; duringsleep the EPSPs are smaller than the threshold potential. A mechanism working like presynaptic inhibition might be responsible for the change of the EPSP amplitude.
5.
The control of the flow of information to the visual cortex according to the level of alertness is probably one of the functions of the lateral geniculate nucleus.
154 citations
TL;DR: A procedure has been developed, making it possible to survey in one figure the neuronal structures and their relationship to the ventricular grooves in the brain stem of the lamprey, Lampetra fluviatilis, and yielded the following results.
Abstract: The investigations of His, Herrick, Johnston and many others have led to the doctrine that the central nervous system fundamentally consists of a number of longitudinally arranged zones or columns, some of which are delimited from each other by distinct ventricular sulci. In order to facilitate the study of this basic morphological pattern in the brain stem, a procedure has been developed, making it possible to survey in one figure the neuronal structures and their relationship to the ventricular grooves in this region. Essentially this procedure involves two steps: first the cell masses and large individual cells are projected upon the ventricular surface, and next the ventricular surface is flattened out, i.e., subjected to a one-to-one continuous topological transformation. Such a topological analysis was carried out on the brain stem of the lamprey, Lampetra fluviatilis, and yielded the following results: The sulcus limitans of His extends throughout the rhombencephalon, but does not enter the midbrain. The rhombencephalic basal plate can be clearly divided into a medial somato-motor, and a lateral viscero-motor zone. The somato-motor zone consists of a rostral extension of the spinal motor column and three reticular nuclei. Rostrally this zone is continuous with the tegmentum mesencephali, which contains another reticular nucleus and the superficial and deep nuclei of III. The reticular nuclei contain groups of large cells. On either side seven of these large cells, three in the midbrain, one in the isthmus and three in the hindbrain, are significantly larger than the others, and are designated as Muller cells. The viscero-motor zone is confined to the hindbrain. It consists of a continuous chain of discrete cell masses: the motor nuclei of V, VII, IX and X. This zone contains in addition the large Mauthner neuron, which is situated between the nuclei of V and VII.
In the rhombencephalic alar plate, separate viscero-sensory and somatosensory zones could not be recognized. The delimitable nuclei in this region all belong to the somato-sensory octavo-lateralis complex. The latter complex extends rostrally into the very small cerebellum which, apart from a zone of periventricular gray and a nucleus cerebelli, harbours the motor nucleus of IV. The sensory centers of the midbrain, i.e., the torus emicircularis and the tectum are caudally continuous with the gray substance of the alar plate of the hindbrain. Large, presumably primary sensory, elements occur in the caudal and ventral part of the rhombencephalic alar plate. Such “dorsal cells” are also present in the spinal cord, but a midbrain equivalent, i.e., nucleus mesencephalicus of V, is entirely lacking.
115 citations
TL;DR: In this paper, an Extended Huckel MO (EHMO) method was used to calculate the adsorption energy of a hydrogen atom over a surface nickel atom, which was shown to be more favorable than adsorbing in some surface holes.
114 citations
TL;DR: It is concluded that binaural additivity of loudness holds for non-zero stimulation of the ears, derived from extensive measurement such as magnitude estimation.
Abstract: A definition of binaural additivity is given in terms of the theory of simultaneous conjoint measurement. Additivity is then tested and verified by a conjoint measurement procedure. Methods for deriving psychophysical scales from such procedures are discussed, and the experimental scales are compared with the usual ratio scales for loudness, derived from extensive measurement such as magnitude estimation. The functions are in good agreement and it is concluded that binaural additivity of loudness holds for non-zero stimulation of the ears.
104 citations
TL;DR: The caldo-active strain YT-P was found to produce a variety of extracellular enzymes, including an amylase and a protease, which were further examined, and it is suggested that they belong to the genus Bacillus.
Abstract: The caldo-active strain YT-P was found to produce a variety of extracellular enzymes, including an amylase and a protease, which were further examined. With azo-casein as a substrate, optimum conditions with respect to enzyme and substrate concentration were determined for the protease. The optimum temperature was found to be 70°C, with a sharp decline to both lower and higher temperatures. The enzyme was found to be extremely heat-stabile, with unaltered activity after 8 hours at 80°C. Optimum conditions for the amylase were also examined. This enzyme was shown to be less heat-stabile, though the temperature optimum was again at 70°C. The activity or stability was not influenced by absence or presence of Ca-ions. The main activity of the amylase was found in the 20–40% ammonium sulfate fraction, which also contained the bulk of the proteolytic enzyme. This strain growth optimally on a variety of carbon sources at 72°C. Typical submicroscopical features are the double-layered cell wall, and a cytoplasmic membrane with a varying number of small dots and dot-free patches. Furthermore the nutritional requirements and submicroscopical features of two other strains, YT-G and YT-F, are described and compared to strain YT-P. Based on the fatty acid composition of the three spore forming caldo-active strains we suggest that they belong to the genus Bacillus, and propose the names B. caldolyticus for strain YT-P, B. caldovelox for strain YT-F, and B. caldotenax for strain YT-G.
102 citations
TL;DR: Substantial, seasonally varying amounts of opsin are present in cattle rhodopsin preparations, which cannot be converted to rhodopin by prior dark adaptation of the excised eyes, and this preparation is of high purity and can be stored for long periods of time.
101 citations
TL;DR: Specific enzyme activity in enzyme preparations obtained from rats with free access to food and stimulated in vivo by secretin and pancreozymin is twice as high as that in enzymes preparations from starved animals.
99 citations
TL;DR: The efferent fiber connections of the cortical areas in the Tegu lizard were studied using the Nauta-Gygax and Fink-Heimer techniques to make observations on terminal degeneration in a middle zone of the molecular layer of the small-celled part of the mediodorsal cortex.
97 citations
TL;DR: In this article, the authors used the molecular beam electric resonance method for the investigation of the hyperfine Λ-doubling transitions ΔJ = 0, ΔF = 0 ± 1 for a number of J values of both the 2II1/2 and 2II3/2 states of the molecules 14n16O and 15N16O.
92 citations
TL;DR: It is shown that 10S and 14S RNA fractions from calf lens direct the synthesis of different polypeptide components of lens crystallin in the ascites cell-free system.
Abstract: SPECIALIZED tissues which synthesize only a small number of different proteins offer obvious advantages as sources of specific and pure messenger RNAs (mRNAs). Presumptive mRNAs have been isolated and partially characterized from reticulocytes1,2, muscle3, myelomas4 and eye lens5. The messenger role of 9S RNA from reticulocytes has been established by its ability to direct the synthesis of haemoglobin in cell-free systems from reticulocytes2 and Krebs 11 ascites tumour cells6 and in Xenopus oocytes7. We show here that 10S and 14S RNA fractions from calf lens direct the synthesis of different polypeptide components of lens crystallin in the ascites cell-free system. These results complement and extend the demonstration, in the accompanying article8, that 14S lens RNA is translated in the reticulocyte lysate.
TL;DR: Results are interpreted as indications for the existence of a regulatory mechanism between mitochondrial respiratory metabolism and the activity of a particular group of genome loci in the polytene chromosomes (puff formation).
Abstract: Inhibition of hydrogen transfer between NADH and Co Q by rotenone or amytal in salivary gland cells of Drosophila hydei maintained in vitro, results in the activation of a particular group of four loci in the polytene chromosomes (puff formation). The response of these loci to the same treatment is enhanced if Na-malonate is present in the incubation medium. — Three of the loci become active if the glands are kept in a medium supplied with antimycin A or 2-heptyl-4-hydroxyquinoline-N-oxide (H QNO), specific inhibitors of the electron transfer between cytochromes b and c. — It was established that a temperature treatment and DNP raise oxygen consumption of the cells to a certain level. Following the same treatments of glands supplied with Na-malate and Na-succinate the raise in oxygen consumption attains a significantly higher level. Under these conditions no response is observed at the genome level. — Whereas DNP, which uncouples oxidative phosphorylation and enhances the respiratory chain reactions, does induce the initiation of puff formation, oligomycin, which inhibits oxidative phosphorylation and suppresses the respiratory chain reactions, is ineffective in initiating puff formation at the specific loci. However, if oligomycin is supplied to the medium in combination with KCN which inhibits the cytochrome oxidase activity, three of the four loci become active. — The presence in the medium of substances which may act as hydrogen acceptors, e.g. menadione or methylene blue, can also result in activation of the chromosome loci. — These results are interpreted as indications for the existence of a regulatory mechanism between mitochondrial respiratory metabolism and the activity of a particular group of genome loci.
TL;DR: Over 85% of the insoluble protein part of cattle rod outer segment membranes appears to consist of rhodopsin protein.
TL;DR: The relationship between β-ecdysone specific changes in genome activity and changes in cell function was investigated and a result was obtained if protein synthesis was inhibited by cycloheximide and if ecdysone is suppled to glands in a medium containing actinomycin D.
TL;DR: Using a trypsin banding technique a D/D and a G/G translocation were identified as D-13/14 and G-21/22.
Abstract: Using a trypsin banding technique a D/D and a G/G translocation were identified as D-13/14 and G-21/22.
TL;DR: The physiological importance of the shorter diffusion distance in the right ventricle of the high altitude adapted rats is discussed and it is suggested that the short diffusion distance may help to keep the tissue O2 partial pressure above the critical value, mainly in extreme situations with high myocardial O2 consumption.
Abstract: In growing rats adapted to a simulated altitude of 3500 m for about 4 weeks and in their controls the evolution of cardiac ventricular weight was followed. The increase of total ventricular weight found in the adapted animals can be attributed exclusively to the increase of right ventricular weight. In other adapted and control animals cardiac capillary densities, muscle fiber diameter and external capillary radius were estimated and fiber—capillary ratio and diffusion distance were calculated. There was an increase of capillary density together with a decrease of muscle fiber density, fiber-capillary ratio and diffusion distance in the right but not in the left ventricle of the adapted rats. The muscle fiber diameters, however, were larger in both heart ventricles of the rats exposed to a simulated high altitude, especially in the right ventricle. This indicates that true hypertrophy of the muscle fibers is mainly responsible for the increase of right ventricular weight. In the left ventricle, however, a hypertrophy of the muscle fibers together with a decrease of stroma components is demonstrated. The physiological importance of the shorter diffusion distance in the right ventricle of the high altitude adapted rats is discussed and it is suggested that the shorter diffusion distance may help to keep the tissue O2 partial pressure above the critical value, mainly also in extreme situations with high myocardial O2 consumption.
TL;DR: MESSENGER RNAs coding for α and β globin chains1, for myosin2 and for the mouse immunoglobin light chains3 have been shown to be translated in a reticulocyte cell-free system.
Abstract: MESSENGER RNAs coding for α and β globin chains1, for myosin2 and for the mouse immunoglobin light chains3 have been shown to be translated in a reticulocyte cell-free system. Messengers are also translated faithfully in the ascites tumour cell-free system4 and in oocytes from Xenopus laevis5.
TL;DR: Gas chromatographic analysis of extracts from Bacillin caldolyticus and Bacillus caldotenax grown at 60, 70, or 80 C showed that both contain branched-chain fatty acids as major constituents at all temperatures tested.
Abstract: Gas chromatographic analysis of extracts from Bacillus caldolyticus and Bacillus caldotenax grown at 60, 70, or 80 C showed that both contain branched-chain fatty acids as major constituents at all temperatures tested. With increasing temperature, a decrease of i-C15 and an increase of i-C17 fatty acids were observed in both strains, as well as a decrease of i-C16 fatty acids corresponding to an increase of n-C16 fatty acids. The most obvious difference was that the shifts observed with B. caldolyticus occurred mainly upon raising the temperature to 10 C above, and in B. caldotenax upon lowering the temperature to 20 C below, the optimal growth temperature.
TL;DR: Liquid cultures of Staphylococcus epidermidis 1580 contained rather small amounts of a bacteriocin, staphylococcin 1580, which was found both in the supernatant fluid and in the cell pellet and could be extracted from the cells with 5% NaCl solution.
Abstract: Liquid cultures of Staphylococcus epidermidis 1580 contained rather small amounts of a bacteriocin, staphylococcin 1580, which was found both in the supernatant fluid and in the cell pellet. It could be extracted from the cells with 5% NaCl solution. The staphylococcin production could not be induced by ultraviolet irradiation or treatment with mitomycin C. Bacteria grown on semisolid medium produced a much larger amount of the compound with a high specific activity. The staphylococcin was purified by ammonium sulfate precipitation, ultracentrifugation, and chromatography on Sephadex columns. The purified material was homogeneous on polyacrylamide gel electrophoresis. The molecular weight was between 150,000 and 400,000. The bacteriocin was composed of protein, carbohydrate, and lipid and consisted of subunits exhibiting a molecular weight of about 20,000. Images
TL;DR: The effect of staphylococcin 1580 appeared to be bactericidal but not bacteriolytic; a large number of gram-positive bacteria were sensitive to Staphylococcus epidermidis 1580 action and was adsorbed to cell walls, cell membranes, and resistant cells.
Abstract: Staphylococcin 1580, produced by Staphylococcus epidermidis 1580, consisted of 41.8% protein, 34% carbohydrate, and 21.9% lipid. In the protein fraction, the acidic amino acids, glutamic and aspartic acid, and the neutral amino acids, glycine and alanine, predominated. Neutral sugars consisted of glucose, galactose, and fucose in a molar ratio of 6:3:1. The purified bacteriocin was not inactivated by heating for 15 min at 120 C in the presence of 0.5% serum albumin and was stable in the pH range from 3.5 to 8.5. The compound was sensitive to the action of the proteolytic enzymes trypsin, Pronase, and chymotrypsin. All gram-negative bacteria tested were resistant; a large number of gram-positive bacteria were sensitive to staphylococcin 1580 action. Growth of stable staphylococcal L-forms was inhibited by the bacteriocin to the same extent as their parent strains. The staphylococcin was adsorbed to cell walls, cell membranes, and resistant cells. The effect of staphylococcin 1580 appeared to be bactericidal but not bacteriolytic.
TL;DR: A review of the literature indicates that 39 cases of coronoid process enlargement have been reported; 13 of these patients had bilateral involvement, and the fact that three patients came from one family proves that there are hereditary aspects to the condition.
TL;DR: The nature and concentrations of the materials employed are believed to make this model of prebiotic nucleotide synthesis the first reported to be consistent with geological constraints.
TL;DR: Glutaminyl-, isoleucyl, leucyl-, lysyl- and methionyl-transfer RNA synthetase can be isolated from a postmicrosomal fraction from rat liver as a complex which resists separation in the following techniques: gel filtration on Sephadex G200, chromatography on DEAE-SephadeX A50, chromochemistry on hydroxyapatite, centrifugation in sucrose gradients and isoelectric
TL;DR: The level of total cholesterol in the testis showed a close correlation with the Sertoli cell lipid cycle, and underwent a rapid increase at the time of postnuptial tubule steatogenesis, suggesting a mobilization of this material during this period.
TL;DR: In the senile sclera perifibrous extracellular lipid deposits are found and the picture of lipid accumulation resembles that in aging cornea and aorta and to a certain extent that in atherosclerosis.
TL;DR: It is possible that this pathological-anatomical substrate is mere a characteristic of dementia, and not of schizophrenia, and further research will be directed to this problem.
Abstract: In this study an analysis is made of the quantitative changes in four areas (10, 4, 24, 17) of the cerebral cortex of patients with schizophrenia, in comparison with the normal cortex. In all areas the relation between neuron number, nuclear volume and depth was measured. Most obvious is the finding of neuronal destruction (57%) which is minimal in the layers II and III (40%) and maximal in the layers IV and V and partially in VI (70%). In combination with this cell-loss, the cortical thickness is diminished over about 20%. This means that also the number of other cortical elements must be reduced. The cell-loss is random, but minimal in area 17. The nuclei are swollen except in area 17. It is possible that this pathological-anatomical substrate is mere a characteristic of dementia, and not of schizophrenia. Further research will be directed to this problem.
TL;DR: In Drosophila hydei, as in other Dipteran species, numerous puffs can be observed along the polytene chromosomes in larval and in some adult cell types, each of these puffs includes a section of the DNA of the genome from which RNA is transcribed.
Abstract: In Drosophila hydei, as in other Dipteran species, numerous puffs can be observed along the polytene chromosomes in larval and in some adult cell types. Each of these puffs includes a section of the DNA of the genome from which RNA is transcribed. Because, in the living cell, transcription of chromosomal DNA may be regarded as an expression of gene activity, the pattern of puffs in any particular type of cell should represent the pattern of active genes. The correctness of this conclusion, however, largely depends upon the criteria by which a puff is defined.
TL;DR: In rats adapted to a simulated altitude of 3500 m cardiac output measured at hypoxia by the direct Fick principle was significantly lower than in the control animals and it is suggested that the decrease of cardiac output might be related to the increase of hematocrit.
Abstract: In rats adapted to a simulated altitude of 3500 m cardiac output measured at hypoxia by the direct Fick principle was significantly lower than in the control animals (mean values 54.3 ml/min and 69.8 ml/min, resp.). The decrease of cardiac output was accompanied by an increase of arterio-venous O2 difference and a decrease of stroke volume in the adapted rats. It is suggested that the decrease of cardiac output might be related to the increase of hematocrit. The adapted rats also showed higher arterial and mixed-venous O2 content (both at hypoxia) and increased O2 capacity. Arterial O2 saturation of the animals previously exposed to simulated high altitude hypoxia was significantly higher (67.3% as against 61.2% in the controls). The standard O2 dissociation curve showed lower oxygen affinity in the blood of the adapted animals but no physiological advantage concerning the transport of O2 to the tissues was found. In another group of animals the Bohr factor was estimated and no difference was found between rat and human blood.
TL;DR: Investigation of the effects of various other factors of possible importance for both systems of Hb and Mb found that there is a decrease of the facilitated oxygen flux with high values of P O 2, particularly in the system Mb + O 2 .