Showing papers by "Utrecht University published in 1982"
TL;DR: In this article, a recent proposal to achieve faster-than-light communication by means of an EPR-type experimental set-up is examined, and it is shown that such superluminal communication is not possible.
1,204 citations
TL;DR: Dynorphin and vasopressin, although they occur in the same cells, appear to be under separate genetic control and presumably arise from different precursors.
Abstract: The opioid peptide dynorphin is widely distributed in neuronal tissue of rats. By immunocytochemical methods, it was shown previously that dynorphin-like immunoreactivity is present in the posterior pituitary and the cells of the hypothalamic neurosecretory magnocellular nuclei which also are responsible for the synthesis of oxytocin, vasopressin, and their neurophysins. By using an affinity-purified antiserum to the non-enkephalin part of the dynorphin molecule it has now been demonstrated that dynorphin and vasopressin occur in the same hypothalamic cells of rats, whereas dynorphin and oxytocin occur in separate cells. Homozygous Brattleboro rats (deficient in vasopressin) have magnocellular neurons that contain dynorphin separate from oxytocin. Thus dynorphin and vasopressin, although they occur in the same cells, appear to be under separate genetic control and presumably arise from different precursors.
407 citations
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01 Jan 1982310 citations
TL;DR: In this article, an analysis of the ability of nonlinear complex least squares fitting to yield useful estimates of parameter values occurring in equivalent Voigt circuits is made, and three-dimensional perspective plots are presented which show the full frequency response of either impedance or admittance data.
273 citations
TL;DR: This review may familiarize ‘newcomers’ with the field of glycoconjugate research with special emphasis on glycoprotein glycans and current knowledge on functional roles of glycans is presented.
Abstract: Since the pioneering work on structure and function of heteroglycans compiled in the classical books edited by A. Gottschalk in 19721, there have been several promising developments in glycoconjugate research, as reviewed in this article.
262 citations
TL;DR: In this paper, the changes in fabric skeleton with decreasing metamorphic grade are proposed as mainly consequent to the deactivation of prism 〈c〉 glide systems as temperature decreases.
249 citations
TL;DR: Changes in recruitment threshold of individual motor units of the human biceps (caput longum), a multifunctional muscle, were investigated and support the view that movements are programmed “directionally”.
236 citations
TL;DR: The binding properties of the adrenal steroid receptor system in rat hippocampus were analyzed in vitro in cytosol binding experiments and in vivo with cell nuclear uptake studies to identify populations of binding sites with high affinity and low capacity.
Abstract: The binding properties of the adrenal steroid receptor system in rat hippocampus were analyzed in vitro in cytosol binding experiments and in vivo with cell nuclear uptake studies. All experimental animals were adrenalectomized 3 days previously for removal of endogenous adrenal steroids. Scatchard analysis of [3H]corticosterone and [3H]dexamethasone in vitro binding in cytosol gave linear plots. Binding parameters for [3H]corticosterone-labeled sites were a maximal binding capacity (Bmax) of 424 fmol/mg protein and a Kd of 3.4 nM and for [3H] dexamethasone-labeled sites, a Bmax of 507 fmol/mg protein and a Kd of 5.0 nM. Scatchard analysis of [3H]aldosterone binding showed two populations of binding sites: one with high affinity (Kd= 2.6 nM) and low capacity (Bma = 80 fmol/mg protein) and the other with low affinity (Kd = 29.8 nM) and higher capacity (Bmax = 347 fmol/mg protein). Inclusion in the incubation medium of 0.6-fold excess unlabeled corticosterone or of 100-fold excess of the “pure” glucocortico...
226 citations
TL;DR: The mechanism by which pyrethroids and DDT prolong the sodium current in Xenopus nodal membrane is investigated and results show that these compounds—despite marked differences in chemical structure—modify sodium channel gating in a strikingly similar way and reduce selectively the rate of closing of the activation gate.
Abstract: Synthetic pyrethroids are a new class of highly active insecticides with great potential for practical application1. They are generally recognized as neurotoxicants that act directly on excitable membranes2,3. Previous studies have shown that the effect of the pyrethroid allethrin closely resembles that of the classical insecticide dichlorodiphenyl trichloroethane (DDT) in the peripheral nervous system of Xenopus laevis4,5. Both compounds induce intense repetitive activity in sense organs and in myelinated nerve fibres. In the lateral-line sense organ this repetitive activity increases with cooling, a phenomenon that may be related to the negative temperature coefficient of toxicity of DDT6 and pyrethroids7 in insects. In frog node of Ranvier, DDT slows the closing of sodium channels that open during depolarization8,9 so that a prolonged sodium tail current persists after the membrane has been repolarized. We have recently found that the pyrethroid allethrin10 causes a similar sodium tail current in the nodal membrane of Xenopus. Pyrethroids11,12 and DDT13,14 are also known to cause prolongation of the sodium current together with repetitive activity in nerve fibres of invertebrates. The prolonged sodium current is thought to be directly responsible for this repetitive activity3,15, and it has been suggested that the sodium channel in the nerve membrane is the major target site of pyrethroids and DDT-like compounds10,12. We have now investigated the mechanism by which pyrethroids and DDT prolong the sodium current in Xenopus nodal membrane. Our results show that these compounds—despite marked differences in chemical structure—modify sodium channel gating in a strikingly similar way and reduce selectively the rate of closing of the activation gate.
223 citations
TL;DR: The volumetric polymerization shrinkage of some composite resin restorative materials was measured with a modified dilatometer and the influences of storage, testing conditions, and mixing ratio on the rigid contraction were studied.
Abstract: The volumetric polymerization shrinkage of some composite resin restorative materials was measured with a modified dilatometer. It is emphasized that only the shrinkage from the start of the gelation, the rigid contraction of the material, is of clinical relevance. The amount of gelation was determined with an instrument that indicates the first moment at which the setting material is rigid enough to exert tensile forces. In addition, the influences of storage, testing conditions, and mixing ratio on the rigid contraction were studied for one light-cured as well as some chemically cured composite resins.
217 citations
TL;DR: In this paper, the size distribution of micelles and micro-emulsion droplets is discussed on the basis of the thermodynamics of these systems, and the size and size distribution can be checked by a variety of techniques, such as centrifugation, light scattering, electronmicroscopy.
TL;DR: A clamp designed for holding tendons in force/elongation studies is described and no slippage occurred when tensile forces up to 13,800 N were applied to horses digital flexor tendons fixed in this clamp.
TL;DR: In this paper, the Pontryagin index for SU(N) gauge fields on the HypertorusT4, seen as a four-dimensional euclidean box with twisted boundary conditions, was studied.
Abstract: We show how to prove and to understand the formula for the “Pontryagin” indexP for SU(N) gauge fields on the HypertorusT4, seen as a four-dimensional euclidean box with twisted boundary conditions. These twists are defined as gauge invariant integers moduloN and labelled byNμv (=−Nμv). In terms of these we can write (ν∈#x2124;)
$$P = \frac{1}{{16\pi ^2 }}\int {Tr(G_{\mu v} \tilde G_{\mu v} )d_4 x = v + \left( {\frac{{N - 1}}{N}} \right) \cdot \frac{{n_{\mu v} \tilde n_{\mu v} }}{4}} $$
. Furthermore we settle the last link in the proof of the existence of zero action solutions with all possible twists satisfying\(\frac{{n_{\mu v} \tilde n_{\mu v} }}{4} = \kappa (n) = 0(\bmod N)\) for arbitraryN.
TL;DR: Findings confirm the finding from the Royal College of General Practitioners Oral Contraceptive Study that the incidence rate of rheumatoid arthritis among OC users was halved.
TL;DR: The increase in social interactions is apparently not due to a general increase in locomotor or exploratory behavior, since no differences in ambulation between individually- and group-housed animals were observed when they were tested together in the social interaction test, and locomotor activities hardly differed in an open field test procedure.
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01 Jan 1982TL;DR: In this article, a model study of passive margin evolution was conducted and it was shown that ageing of passive margins alone does not make them more suitable sites for initiation of subduction, but extensive sediment loading on young lithosphere might be an effective mechanism for closure of small ocean basins.
Abstract: Although the initiation of subduction is a key element in plate tectonic schemes for evolution of lithospheric plates, the underlying mechanisms are not well understood. Plate rupture is an important aspect of the process of creating a new subduction zone, as stresses of the order of kilobars are required to fracture oceanic lithosphere1. Therefore initiation of subduction could take place preferentially at pre-existing weakness zones or in regions where the lithosphere is prestressed. As such, transform faults2,3 and passive margins4,5 where the lithosphere is downflexed under the influence of sediment loading have been suggested. From a model study of passive margin evolution we found that ageing of passive margins alone does not make them more suitable sites for initiation of subduction. However, extensive sediment loading on young lithosphere might be an effective mechanism for closure of small ocean basins.
TL;DR: The distribution of vasotocin and isotocin in the brain of the rainbow trout Salmo gairdneri was investigated by the unlabeled antibody enzyme method, by using purified antisera against arginine vasotopressin and oxytocin innervation of the rat brain.
Abstract: The distribution of vasotocin and isotocin in the brain of the rainbow trout Salmo gairdneri was investigated by the unlabeled antibody enzyme method, by using purified antisera against arginine vasotocin and isotocin. In the preoptic nucleus no clear differences were observed in the distribution of vasotocin- and isotocin-containing cells. Vasotocin and isotocin innervation was found in most brain regions, though in general isotocin fibers were much more abundant. The area dorsalis pars medialis of the telencephalon, the saccus dorsalis, and the basal part of the nucleus recessus posterioris were found to be innervated by vasotocin and scarcely by isotocin fibers. In the nucleus habenularis, the nucleus recessus lobus lateralis, the nucleus preglomerulosus pars medialis, and the tectum mesencephali isotocin fibers prevailed. These findings in the trout brain are compared with the vasopressin and oxytocin innervation of the rat brain.
TL;DR: The specificity of the 5-HT response in the hippocampus corresponds to the properties of the glucocorticoid receptor system in rat hippocampal neurons.
TL;DR: The relationship of the high value for B‐50 phosphorylation in the septum to the sensitivity of that brain area to ACTH1–24 is discussed and the data were interpreted as pointing to the localization of B‐ 50 in nervous tissue.
Abstract: The localization of the phosphoprotein B-50 (molecular weight 48,000, isoelectric point 4.5) in the rat has been studied. Inspection of endogenous phosphorylation patterns of the particulate as well as the cytosolic subcellular fractions from a variety of peripheral organs failed to demonstrate phosphorylation of a molecular weight 48,000 protein. Only in the particulate fractions from brain tissue was there endogenous phosphorylation of the B-50 protein. Two-dimensional analysis (isoelectric focusing and sodium dodecyl sulfate polyacrylamide gel electrophoresis) and an immunochemical detection method employing an anti-B-50 antiserum revealed the presence of B-50 in particulate material from brain, but not in that of other tissues. Therefore the data were interpreted as pointing to the localization of B-50 in nervous tissue. In addition, the regional distribution of endogenous B-50 phosphorylation was studied using synaptosomal plasma membranes (SPM) obtained from individual rat brain regions. The highest value was found in SPM of septal origin, the lowest in SPM from the medulla spinalis. The relationship of the high value for B-50 phosphorylation in the septum to the sensitivity of that brain area to ACTH1–24 is discussed.
TL;DR: The structural organization of aqueous dispersions of 1,2-dioleoylphosphatidic acid has been investigated by freeze-fracture electron microscopy in relation to variations in pH, divalent cations and the local anaesthetic chlorpromazine.
TL;DR: The results are consistent with the hypothesis that the pancreatic enzyme binds to defect sites at the phase boundaries in substrate bilayers induced by the products and can be adequately described by a single equilibrium.
TL;DR: The first numerical determination of the thermodynamic isotropic-nematic transition in a simple three-dimensional model fluid, viz., a system of infinitely thin hard platelets, is reported in this article.
Abstract: The first numerical determination of the thermodynamic isotropic-nematic transition in a simple three-dimensional model fluid, viz., a system of infinitely thin hard platelets, is reported. Thermodynamic properties were studied with use of the constant-pressure Monte Carlo method; Widom's particle-insertion method was used to measure the chemical potential. The phase diagram is found to differ considerably from predictions of a second-virial ("Onsager") theory. Virial coefficients up to the fifth were computed; b5 is found to be negative.
TL;DR: The results demonstrate that the accelerated hydrolysis following the latency phase of the reaction progress curve is due to the product-assisted binding of the enzyme to the substrate bilayer by chaning the number of bindings sites and therefore the binding equilibrium.
TL;DR: In this article, the Hartree-Fock approximation of dipole, quadrupole and octopole moments and dipole polarizabilities are reported for H2, CH4, NH3, H2O, HF, HCN, H 2CO, H3CF and HCOOH.
Abstract: Calculated dipole, quadrupole and octopole moments and dipole polarizabilities are reported for H2, CH4, NH3, H2O, HF, HCN, H2CO, H3CF and HCOOH in the Hartree—Fock approximation. Nine different basis sets are employed, ranging from a minimal basis to a large triply polarized basis. It is argued that in order to achieve an accuracy of 0.001 hartree in intermolecular interaction energies, the errors in computed monomer moments should be less than 0.03, 0.15 and 0.75 au for μ, θ and Ω, respectively, while α should be correct to within 2 a03. Measured by these standards, the DZPP and larger sets provide results close to the Hartree—Fock limit, but the commonly used energy-optimized DZP basis proves unsatisfactory. An alternative moment-optimized DZP′ basis is proposed which is shown to be the smallest basis yielding results acceptably close to the Hartree—Fock limit. Vibrational corrections are estimated for the hydrides and turn out to be small. Comparison w ith experiment then shows that correlation corrections are important, especially for μ and α. Details on contraction schemes and standard scale factors for the different basis sets are given in the Appendix.
TL;DR: Results indicate a close antigenic relationship between TGEV, FIPV, and canine coronavirus due to common determinants on the three major virion proteins.
Abstract: Transmissible gastroenteritis virus of swine (TGEV), feline infectious peritonitis virus (FIPV), and canine coronavirus were studied with respect to their serological cross-reactivity in homologous and heterologous virus neutralization, immune precipitation of radiolabeled TGEV, electroblotting, and enzyme-linked immunosorbent assay using individual virion polypeptides prepared by polyacrylamide gel electrophoresis. TGEV was neutralized by feline anti-FIPV serum, and the reaction was potentiated by complement; heterologous neutralization involved antibody reacting with the peplomer protein (P), the envelope protein (E), and cellular (glycolipid) components incorporated into the TGEV membrane. Electrophoretic analysis of immune precipitates containing [35S]methionine-labeled disrupted TGEV and feline anti-FIPV antibody confirmed the reaction with the P and E polypeptides and showed the nucleocapsid protein (N) in addition. Electroblotting, followed by incubation with antibody, 125I-labeled protein A, and fluorography, disclosed cross-reactions between the three viruses at the N and E levels and revealed differences in the apparent molecular weights of the latter. Enzyme immunoassays performed with standard amounts of immobilized P, N, and E polypeptides of the three viruses showed recognition of the antigens by homologous and heterologous antibody to comparable degrees. These results indicate a close antigenic relationship between TGEV, FIPV, and canine coronavirus due to common determinants on the three major virion proteins. The taxonomic implications of these findings are discussed.
TL;DR: Vijverberg H.P.M. & van den Bercken J.
Abstract: Vijverberg H.P.M. & van den Bercken J.1982 Neuropathology and Applied Neurobiology8, 421–440
Annotation. Action of pyrethroid insecticides on the vertebrate nervous system
The neurotoxic action of the synthetic pyrethroid insecticides has received much interest in recent years, as the number of available pyrethroids and their practical applications have greatly increased. Although the majority of pyrethroids have a low oral toxicity to mammals, they may cause severe neurotoxic symptoms whenever they reach the nervous system in sufficient amount.
The principal effect of pyrethroids in the vertebrate nervous system is to induce repetitive activity, particularly in the sensory nervous system. This repetitive activity originates from a prolongation of the transient increase in sodium permeability of the nerve membrane associated with excitation. Available evidence indicates that pyrethroids primarily interfere with the sodium channels in the nerve membrane. All active pyrethroids affect sodium channel gating in a similar manner, but marked differences in neurotoxic activity exist between the various pyrethroids, especially between ot-cyano and non-cyano compounds.
TL;DR: The data suggest that women whose menarche occurs early not only have a longer duration of exposure to estrogens during years which are probably important in the initiation of breast cancer but, in addition, their exposures are at a higher level during those years and probably at later ages also.
Abstract: In 511 nulliparous women aged 15-19 years and 347 aged 30-39, an analysis has been undertaken of the relationship of urine concentrations of the three principal estrogens to age, age at menarche and Quetelet's index of adiposity. The analysis was undertaken by means of multiple regression, controlling for each of the 12 centers from which the data originated, as well as for the other study variables. In the younger women, age was strongly and positively related to concentrations of E1 and E2 and less so to E3. In the age group 30-39, follicular phase specimens showed positive relationships with age for all three fractions but luteal specimens did not. Age at menarche showed inverse relationships to levels of E1 and E2 which were significant in the younger but not in the older age group. The associations of estrogens with Quetelet's index were weak and not statistically significant. The data suggest that women whose menarche occurs early not only have a longer duration of exposure to estrogens during years which are probably important in the initiation of breast cancer but, in addition, their exposures are at a higher level during those years and probably at later ages also. These observations support the hypothesis that the mechanism of the association of early menarche with breast cancer risk is via the association of both with estrogen stimulus.
TL;DR: In this article, the acute median lethal concentrations of equitoxic mixtures of 8 and 24 toxicants with diverse modes of action to guppies were determined, and the results were expressed by means of the Mixture Toxicity Index (MTI).
TL;DR: In this paper, the optical bandgap of glow-discharge and sputter-deposited a-Si was deduced from measurements of the absorption coefficient α using a linear extrapolation of (αhvn)1/3 as a function of the photon energy h v. The exponent 1/3 is used instead of 1/2, resulting in a much better fit to the data.
Abstract: The optical bandgap of glow-discharge and sputter-deposited a-Si has been deduced from measurements of the absorption coefficient α using a linear extrapolation of (αhvn)1/3 as a function of the photon energy h v. The exponent 1/3 is used instead of 1/2, resulting in a much better fit to the data. The influence of the method of extrapolation on the resulting value for the optical bandgap has been assessed.
TL;DR: Patchwork-like structures characterize the membranes of mitochondria, quenched from 37 degrees C, as well as those incubated with Ca2+, Mn2+, Mg2+ and apo- or cytochrome c, as the result of the fracture plane, jumping from the outer to the inner limiting membrane and vice versa at sites of contact.