Showing papers by "Radboud University Nijmegen published in 1973"
359 citations
TL;DR: In this article, the authors investigated the effect of a shift of the dissociation curve to the right as reflected in the mixed venous oxygen pressure and the role of this displacement in pulmonary gas exchange with particular reference to the alveolar-arterial oxygen pressure difference and the pulmonary diffusing capacity for oxygen.
Abstract: A shift of the oxygen dissociation curve to the right is often interpreted as an adaptation to hypoxia favorable for tissue oxygen supply. However, animals native to high altitude tend to show a rather high oxygen affinity. In order to elucidate this apparent discrepancy we investigated by numerical computer studies 1. the effect of a shift of the dissociation curve to the right as reflected in the mixed venous oxygen pressure, and 2. the role of this displacement in pulmonary gas exchange with particular reference to the alveolar-arterial oxygen pressure difference and the pulmonary diffusing capacity for oxygen. A right shift had a favorable effect only in the range of moderate hypoxia (and of normoxia) whereas there was a detrimental effect with severe hypoxia. The most important criterion for this distinction was the direction of the change in steepness of the physiological dissociation curve (straight line between arterial and venous points). A favorable effect was associated with a steeper slope after the shift, an unfavorable effect with a less steep slope. There was only a minor influence of a right shift on the oxygen diffusion gradient in the lung. Comparison between man (higher affinity) and rat (lower affinity) suggests that animals of small size with high metabolic rate (high arteriovenous oxygen difference) living in normoxic or possibly exposed to moderately hypoxic condition only are better served by a relatively low oxygen affinity whereas animals native to high altitude are better adapted to severe hypoxia when having a high oxygen affinity.
127 citations
TL;DR: The strong locomotor stimulation following injection of ergometrine into the nucleus accumbens was inhibited by low doses of haloperidol and pimozide given intraperitoneally and Pretreatment with α-methyl-p-tyrosine had no influence on this motor activity.
112 citations
TL;DR: The findings in these cysts strengthen the idea that the oral mucosa plays an important role in the origin of many keratocysts, and advocate excision of the overlying mucosa in the area where the cysts adhere to the mucosa.
101 citations
TL;DR: The thermodynamical activities of FA and OHA are sufficient to account for the dependence on x, and the solubility of the solid solutions in aqueous solutions at certain pH values was calculated.
Abstract: THE free enthalpy of formation of solid solutions of hydroxyapatite (OHA) and fluorapatite (FA) at 25° C has been determined1. I have used these thermodynamical data to calculate (Driessens, unpublished) the solubility of the solid solutions in aqueous solutions at certain pH values. For this purpose, the following relations were derived: where subscript (s) means that the preceding molecular unit is part of the solid solution; subscript (1) means that the preceding ion is dissolved in the aqueous solution; K1OHA and K1FA are the apparent solubility products of the components OHA and FA over the solid solution respectively: they depend on x; KOHA and KFA are the solubility products of pure OHA and pure FA respectively: they are independent of x; aOHA and aFA are the thermodynamical activities of FA and OHA, which are sufficient to account for the dependence on x.
78 citations
TL;DR: Sets of theoretical concentration-effect curves predicted by the new model were compared with experimental results obtained from functional antagonism and functional synergism studies and the agreement between the characters of the sets of theoretical and experimental curves was satisfactory.
77 citations
TL;DR: Only the animals with a low permeability demonstrated a sequence with an increase of the chain length and a decrease of the mean number of double bonds of the hydrocarbon chains of the lipids in combination with a decrease in the glycerol permeability of the red blood cell.
72 citations
TL;DR: Lenses of 3-month-old calves were divided into nine concentric layers and the highest content of γ-crystallin was found in the nucleus and the activity of lens leucine aminopeptidase was found to be highest in the outer cortex fractions, i.e. according to the age of the fibre cells.
70 citations
TL;DR: In this article, a new model of functional interaction introduced in the literature was verified in a number of experimental situations and the theoretical predictions based on the model were shown to correspond with the results obtained with different types of drugs and in different test systems.
70 citations
TL;DR: Dementia seems to be related to a change in the interspatial arrangement of the efferent and afferent elements of the cortex, and the most integrative part of the cerebral cortex shows the most resistance to destruction.
Abstract: An analysis of four areas of the cerebral cortex, from pia to white matter, in presenile dementia, demonstrated a substantial and constant neuron loss of 57% in all areas. In contrast with normal ageing, this cell loss is not continuous over the whole cortex. It is maximal in the lower cortical half. The conclusion was drawn that presenile dementia is not a form of early ageing. Dementia seems to be related to a change in the interspatial arrangement of the efferent and afferent elements of the cortex. The most integrative part of the cerebral cortex (layers II and III) shows the most resistance to destruction.
69 citations
TL;DR: A fast, reliable and sensitive method for the assay of 3,5′-AMP phosphodiesterase (adenosine 3′, 5′-monophosphate phosphohydrolase, EC 3.4.c) is described, which is also applicable to homogenates and crude enzyme preparations containing enzymes catalyzing the breakdown of the reaction product 5,5-AMP.
TL;DR: The treatment of blushing is described: assertive training is useful for patients with symptomatic erythema and erythrophobia, and Hyperhidrosis can be treated byassertive training and systematic desensitization.
Abstract: SUMMARY
Behaviour therapy provides important psychotherapeutic possibilities for the treatment of dermatological disorders. Compulsive scratching and trichotillomania can be treated by aversive conditioning, or by the token economy technique. The treatment of blushing is described: assertive training is useful for patients with symptomatic erythema and erythrophobia. Hyperhidrosis can be treated by assertive training and systematic desensitization.
TL;DR: It is shown that electrical stimulation of the medial part of the caput caudati results in behavioral responses similar to those evoked by dopamine application into the area, and that these responses are inhibited by blockade of the striatal dopamine system on the one hand, and facilitated by activation of the Striatal dopamine System on the other hand.
TL;DR: In this paper, low energy ΛN-and ΣN-scattering has been calculated in a potential model by solving the multichannel Schrodinger equation, where Meson theoretic potentials are used which describe the exchange of nonets of pseudoscalar and vector mesons and uncorrelated two pion exchange.
TL;DR: The findings in a family with the basal-cell nevus syndrome are presented and a new approach to the extirpation of jaw cysts is given special attention based upon the relationship between the nevoid skin lesions and the jaw Cysts.
TL;DR: The data showed that the binding of 2,3-diphosphoglycerate to HbO2 is functionally significant, and it appeared that at pH 6.8 the proton uptake per molecule of DPG bound is larger for HBO2 than for Hb.
TL;DR: In 248 children, varying in age from 6 to 18 years, skin distraction during anteflexion between the zero mark and a mark 15 cm above it, was found to be more than 4.8 cm in all but 2 cases.
Abstract: Skin traction between two fixed points on the midline of the back during anteflexion was tested as a parameter of the anteflexibility of the lumbar spine. The starting mark was placed on the spinou...
TL;DR: It is concluded that illumination of rhodopsin in vivo will not uncover additional SH groups, although the reactivity of one exposed SH group may increase somewhat, and this findings exclude a role of SH groups in the covalent binding of the chromophore.
TL;DR: The development of techniques for the isolation of distinct chromosome parts, and techniques for in situ nucleic acid hybridization have illustrated the manifold opportunities offered for studies on the synthetic activities of the genome by utilization of cytological and biochemical methods.
Abstract: Publisher Summary This chapter describes the synthetic machinery producing the two most important categories of macromolecules in living organisms, DNA and RNA. Polytene chromosomes, especially those of Diptera are excellent and unique tools for studies on genetic problems in conjunction with chromosome cytology in higher organisms. In Diptera, polyteny is widespread among larval tissues (including esophagus; salivary glands; fore-, mid-, and hindgut; gastric ceca, Malpighian tubules; fat body; tracheal wall cells; muscle; and certain types of cell in the nerve ganglia), but it can also be observed in some tissues and special cell types of the pupa (trichogen and thormogen cells present in developing bristle sockets and certain cells in the epidermis of the footpads, or pulvilli of the pretarsus) and in the adult (Malpighian tubules and ovarian nurse cells). The development of techniques for the isolation of distinct chromosome parts, and techniques for in situ nucleic acid hybridization, have illustrated the manifold opportunities offered for studies on the synthetic activities of the genome by utilization of cytological and biochemical methods. Polytene chromosomes promise to play an important role in the clarification of the investigations related to the mechanisms by which genetic information in the eukaryotic cell is handled during growth and development.
TL;DR: The place of folic acid in the biochemistry of epileptogenesis may be very important in the light of its presence in normal metabolism, its strong epileptogenic action after passing the blood-brain barrier, and its decreasing serum levels during anticonvulsant therapy.
TL;DR: Binding of the anticholinergic agent 3 H-dexetimide to subcellular fractions of the caudate nucleus of the male Wistar rat was studied by equilibrium dialysis and appears to involve the muscarinic type of acetylcholine receptor (AchR), correlates well with the physiological response of the AchR as can be concluded from displacement experiments using cholinergic and non-cholinergic ligands.
TL;DR: Although strain and line differences were found for behavior, temperature, and adrenal activity, no specific genetic relationship could be established between the behavioral and the physiological variables.
Abstract: Rearing behavior, locomotor activity, body temperature, and adrenal activity were recorded in male mice from two inbred strains and from two lines selected for rearing frequency. Significant positive correlations between rearing and locomotion indicated that loci responsible for rearing performance may act through a system which regulates the level of arousal. Although strain and line differences were found for behavior, temperature, and adrenal activity, no specific genetic relationship could be established between the behavioral and the physiological variables.
TL;DR: Rate equations have been developed which describe the concentration dependence for ion absorption by a two site-single carrier transport system for those cases in which the ion transport can be considered to be formally equivalent with an enzymic process.
TL;DR: In this paper, α-crystallin was isolated from extracts of the epithelium, from seven successive concentric layers of the cortex and the nucleus of calf lenses, from 6 M urea.
TL;DR: The isolation in S. carlsbergensis of a mutant (C2), constitutive for maltase and for maltose transport is described, and the properties of C2 are discussed and compared with litterature data on positive enzyme regulation.
Abstract: 1.
The isolation in S. carlsbergensis of a mutant (C2), constitutive for maltase and for maltose transport is described. This mutant, in crosses behaving as closely linked or allelic to MAL6, is different from the constitutive MAL4-mutant, described by other authors, in four respects: C2 is recessive to the wild type; the mutant is sensitive to catabolite repression; the level of maltase is not superinducible by maltose; and maltase produced in response to C2 is not different from wild type maltase.
2.
Hybrids made by crossing C2 with a number of mal6-mutants grow on maltose and maltase is induced by maltose as in the wild type MAL6-strain.
3.
The properties of C2 are discussed and compared with litterature data on positive enzyme regulation.
TL;DR: Osmotic flow through gall bladder mucosa is mainly via the cellular membranes, i.e. the extracellular shunt, which is the main route for passive ion permeation, does not contribute significantly to the osmotic water flow in response to a sucrose gradient.
TL;DR: Reynafarje's (1963) spectrophotometric method was modified for the study of myoglobin concentration in rat hearts and a severe cardiomegaly developed which was most pronounced in the right ventricle.
Abstract: Reynafarje's (1963) spectrophotometric method was modified for the study of myoglobin concentration in rat hearts. The influence of age and body weight was evaluated and the age was found to be better correlated with myoglobin concentration than the weight. The influence of simulated altitude of 3500 m was studied in animals exposed to hypoxia at the age of about 34 days and in animals born in the low pressure chamber. In the first group a higher myoglobin concentration was found but only in the right ventricle, together with unilateral hypertrophy, as compared with control animals. In the group of animals born at simulated altitude a severe cardiomegaly developed which was most pronounced in the right ventricle. The myoglobin concentration in the hearts from this group was unchanged in the right ventricle and was lower in the left ventricle and septum.
TL;DR: A specific, 0.1–0.3-µm large ribonucleoprotein complex consisting of a central core with stalklike extensions on top of which 280–320-Å ribon nucleoprotein particles are situated is found in an experimentally activated chromosome region of the polytene chromosomes of Drosophila hydei.
Abstract: A specific, 0.1-0.3-microm large ribonucleoprotein complex consisting of a central core with stalklike extensions on top of which 280-320-A ribonucleoprotein particles are situated is found in an experimentally activated chromosome region, 2-48C, of the polytene chromosomes of Drosophila hydei. Alkaline hydrolysis, RNAse digestion, and uranyl-EDTA-lead staining indicated the ribonucleoprotein character of the 280-320-A particles, whereas the central core seems to be devoid of RNA. The characteristic complexes are present in the nucleoplasm and at the nuclear membrane, but absent from the cytoplasm. It is suggested that the large RNP complexes are the specific products of the puff at 2-48C. Complexes similar to the ones described have not been observed in any other region of the polytene salivary gland chromosomes of this species.
TL;DR: Introduction of the small positively charged acetimidine group has little effect on the structure of rhodopsin, in sharp contrast to the introduction of the large uncharged trinitrophenyl group.
TL;DR: Puff 2–48C produces large quantities of a unique RNP-product; globular 140–220 Å particles which aggregate to stable complexes of 0.2 μ in diameter which have never been observed in any other puff of Drosophila hydei.
Abstract: Vitamin B6 induces in vivo as well as in vitro the appearance of a puff at region 2–48C in Drosophila hydei. At concentrations of 10−2 M or lower, region 2–48C is the only region responding to vitamin B6 provided that oligomycin is present in the incubation medium. Pyridoxal phosphate and pyridoxamine phosphate supplied to medium containing oligomycin induce upon incubation of salivary glands a larger puff at 2–48C. — Puff 2–48C produces large quantities of a unique RNP-product; globular 140–220 A particles which aggregate to stable complexes of 0.1–0.2 μ in diameter. Upon continuous in vitro incubation with vitamin B6, puff 2–48C becomes loaded with these aggregates which have never been observed in any other puff of Drosophila hydei.