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Showing papers by "Radboud University Nijmegen published in 1983"


Journal ArticleDOI
TL;DR: The finite element method was introduced to orthopedic biomechanics in 1972 to evaluate stresses in human bones and has been applied with increasing frequency for stress analyses of bone and bone-prosthesis structures, fracture fixation devices and various kinds of tissues other than bone.

534 citations


Journal ArticleDOI
TL;DR: In this paper, a series of experiments is reported in which subjects describe simple visual scenes by means of both sentential and non-sentential responses, and the data support the following statements about the lexicalization (word finding) process.

396 citations


Journal ArticleDOI
TL;DR: The distribution of serotonin-immunoreactive varicosities in the paraventricular (PVH) and supraoptic (SO) nuclei was charted in normal immunohistochemical material and the probable cells of origin of these projections were identified using a combined retrograde transport-IMmunohist biochemical method.

383 citations


Journal ArticleDOI
01 Aug 1983-Nature
TL;DR: The results suggest that the polymorphism in the mitogenic effect of these IgG1 antibodies is caused by polymorphismIn monocyte function, possibly at the level of the Fc receptor that reacts with mouse IgG 1.
Abstract: It has recently been described that monoclonal antibody OKT 3, that reacts with the T3 determinant on all peripheral T lymphocytes in man, is also mitogenic for T cells1,2. We have produced two monoclonal antibodies (WT 31 and WT 32) which apparently react with the T3 antigen3. We have now tested the mitogenic effect of these antibodies and compared it with the mitogenicity of three other anti-T3 monoclonal antibodies, OKT 3, UCHT 1 (ref. 4) and anti-Leu 4 (ref. 5). Two distinct patterns were observed. WT 32 and OKT 3, both of the IgG2a subclass, were mitogenic for human T cells in all cases studied. By contrast, WT 31, UCHT 1 and anti-Leu 4, all of the IgG1 subclass, were devoid of mitogenic effect in 30% of the individuals tested (non-responders). The mitogenicity of all five anti-T3 antibodies was fully dependent on the presence of monocytes. Addition of purified monocytes from a responder to purified lymphocytes from a non-responder induced responsiveness to both IgG1 and IgG2a anti-T3 antibodies. These results suggest that the polymorphism in the mitogenic effect of these IgG1 antibodies is caused by polymorphism in monocyte function, possibly at the level of the Fc receptor that reacts with mouse IgG1.

314 citations


Journal ArticleDOI
TL;DR: An analytical expression is presented for the solid angle subtended by a plane triangle at some arbitrary point in space, and the time required for numerical computation is cut down to one third.
Abstract: An analytical expression is presented for the solid angle subtended by a plane triangle at some arbitrary point in space. Using this expression, the time required for numerical computation is cut down to one third.

308 citations


Journal ArticleDOI
TL;DR: Intermediate-sized filament proteins (IFP) are tissue specific in that antibodies to keratin, vimentin, desmin, glial fibrillary acidic protein (GFAP) and the neurofilament proteins can distinguish between cells of epithelial and mesenchymal origin as well as of myogenic and neural origin respectively.
Abstract: Intermediate-sized filament proteins (IFP) are tissue specific in that antibodies to keratin, vimentin, desmin, glial fibrillary acidic protein (GFAP) and the neurofilament proteins can distinguish between cells of epithelial and mesenchymal origin as well as of myogenic and neural origin respectively. Malignant cells retain their tissue-specific IFP, which makes it possible to use these antibodies in tumour diagnosis. Carcinomas are exclusively detected by antibodies to keratin. Monoclonal antibodies to keratin have allowed the differentiation between subgroups of epithelial tumours until now between adenocarcinomas and squamous cell carcinomas. Lymphomas, melanomas and several soft tissue tumours are distinctly recognized by antibodies to vimentin. On the other hand, rhabdomyosarcomas and leiomyosarcomas are positive for desmin, while astrocytomas give a strong reaction with GFAP antibodies. Thus, antibodies to IFP are useful tools for differential diagnosis in surgical pathology.

300 citations


Journal ArticleDOI
TL;DR: This paper argued that the location of the nucleus of the intonation contour is rule-governed, with the assumption that the main functions of the location are to signal the focus distribution of the sentence and to signal whether the sentence is or is not meant as a counter-assertion.
Abstract: This article argues for the hypothesis that the location of the nucleus of the intonation contour is rule-governed. The term ‘nucleus’ is taken to refer to what has elsewhere been discussed as the ‘nuclear syllable’ (Crystal, 1969), ‘tonic’ (Halliday, 1967a), ‘sentence stress’ (Schmerling, 1976), ‘[I stress]’ (Chomsky & Halle, 1968), and ‘Designated Terminal Element’ (Liberman & Prince, 1977) (ignoring certain differences of analysis, such as that between double-nucleus and single-nucleus interpretation of some contours). Drawing on the facts of English and Dutch, it does so by attempting to identify the linguistic options available to speakers that are relevant to the location of the nucleus. The main argument hinges on the assumption that the chief functions of the location of the nucleus are (1) to signal the focus distribution of the sentence and (2) to signal whether the sentence is or is not meant as a counter-assertion, with the proviso that in many instances the location of the nucleus allows of more than one interpretation of one or both variables. Section 1 devotes some discussion to the problem of predictability, while the concepts of ‘focus’ and ‘normal stress’ are explored in Sections 2 to 4. Section 5 states the sentence accent assignment rule (SAAR), giving illustrations of its application. In Section 6, special attention is devoted to the pragmatic effects of SAAR in subject + predicate sentences. Section 7 attempts to give a fuller definition of the constituents the rule refers to and puts a general condition on its application. Section 8 introduces the variable mode, while Section 9 defines the problem of the location of the nucleus in sentences with minimal focus and introduces another accent assignment rule (PFR). A summary in the form of a set of propositions concludes the article. I should like to point out that most of the examples in this article are attested; it is only the more pedestrian ones that have been made up for the purpose of illustrating certain points.

269 citations


Journal ArticleDOI
TL;DR: Single unit recordings have provided a basis for understanding the auditory system, especially about how it behaves under stimulation with simple sounds such as clicks and tones, and one approach gives a representation of nervous system activity in the form of peri-stimulus-time histograms, period histogram, iso-intensity rate curves and frequency tuning curves.
Abstract: Single unit recordings have provided us with a basis for understanding the auditory system, especially about how it behaves under stimulation with simple sounds such as clicks and tones. The experimental as well as the theoretical approach to single unit studies has been dichotomous. One approach, the more familiar, gives a representation of nervous system activity in the form of peri-stimulus-time (PST) histograms, period histograms, iso-intensity rate curves and frequency tuning curves. This approach observes the neural output of units in the various nuclei in the auditory nervous system, and, faced with the random way in which the neurons respond to sound, proceeds by repeatedly presenting the same stimulus in order to obtain averaged results. These are the various histogram procedures (Gerstein & Kiang, 1960; Kiang et al. 1965).

247 citations


Journal ArticleDOI
TL;DR: A highly sensitive radioimmunoassay for cholecystokinin (CCK) without any cross-reactivity with gastrin is described and when frozen at -20 degrees C plasma CCK was stable for at least 6 months.

237 citations


Journal ArticleDOI
TL;DR: With this assay, Lipidex 1000 appeared to be useful for the delipidation of protein samples at 37 degrees C and for a radiochemical assay of fatty acid-binding by microgram amounts of protein at 0 degree C.

230 citations


Journal ArticleDOI
TL;DR: The authors investigated how far automatic spreading activation (ASA) spreads in semantic memory and found that one-step spread from the prime's representation to those of its direct associates is possible.

Journal ArticleDOI
TL;DR: A specific and sensitive double immunocytochemical staining for the visualization of glutamate decarboxylase (GAD) and serotonin (5-HT) on the same brain section is developed and cell bodies containing both antigens are observed in each raphe nuclei.

Journal ArticleDOI
TL;DR: The growth response by using the four-week ulnar growth rate, a sensitive index of short-term growth that correlates with height velocity, suggests that there is a biphasic dose–response curve for the effect of estrogen on growth.
Abstract: PATIENTS with Turner's syndrome are short and lack a pubertal growth spurt.1 Estrogen has been implicated as one factor that stimulates the normal pubertal growth spurt, yet estrogen in high doses has also been used to inhibit growth.2 3 4 This suggests that there is a biphasic dose–response curve for the effect of estrogen on growth. To evaluate this possibility, we studied the effect of estrogen dose on growth rate in patients with Turner's syndrome. We assessed the growth response by using the four-week ulnar growth rate, a sensitive index of short-term growth that correlates with height velocity.5 We found that administration . . .

Journal ArticleDOI
01 Nov 1983-Cell
TL;DR: Comparison of the amino acid sequence of vimentin with prekeratin sequences shows that there is lesser homology of primary structure, but both the position and size of alpha-helical regions are strongly conserved.

Journal ArticleDOI
TL;DR: It was concluded that the laminar organization of the tectum is primarily relevant for multimodal integration and that the tECTal cell types each receive a characteristic sample out of the multi-modal information available in the different tectal layers.

Journal ArticleDOI
TL;DR: In this article, an algorithme simple for decrire les valeurs dependant du temps d'un systeme de spin sans relaxation durant l'experience d'impulsions multiples is presented.

Journal ArticleDOI
02 Jun 1983-Nature
TL;DR: The results presented here show that Ia antigens in mouse allografts are also present on the vascular endothelium but their expression is variable and dependent on the immunological status of the recipient, suggesting that vascular endothelial cells can act as targets in Ia-incompatible skin allografted rejection.
Abstract: Ia antigens are membrane-bound glycoproteins that play a part in antigen recognition and subsequent cell–cell interactions in the immune response. In the mouse they are coded for by the I region of the major histocompatibility complex H–2 and have been demonstrated on B lymphocytes, monocytes, activated T cells, macrophages and dendritic cells, including Langerhans cells1,2. Ia-like antigens have also been detected on the vascular endothelium in man3–6 and on epidermal keratinocytes in rats7,8 but expression on the latter cells was induced by a graft-versus-host reaction or by contact hypersensitivity9. In the mouse, previous studies have suggested that Ia antigens in skin are restricted to epidermal Langerhans cells and it was thought that these were the targets for Ia-dependent rejection of skin allografts. The results presented here show that Ia antigens in mouse allografts are also present on the vascular endothelium but their expression is variable and dependent on the immunological status of the recipient. These findings suggest that vascular endothelial cells can act as targets in Ia-incompatible skin allograft rejection.

Journal ArticleDOI
TL;DR: The enzyme system involved in the methyltransfer from methanol to 2-mercaptoethanesulfonate (HS-CoM) was resolved into two enzyme fractions and one enzyme appears to be a cobalamin-containing protein, which is oxygen sensitive.
Abstract: 2-(Methylthio)ethanesulfonate (CH3S-CoM) is formed as an intermediate in methanogenesis from methanol by cell-free extracts of Methanosarcina barkeri. The enzyme system involved in the methyltransfer from methanol to 2-mercaptoethanesulfonate (HS-CoM) was resolved into two enzyme fractions. One enzyme (methanol: 5-hydroxybenzimidazolylcobamide methyltransferase) appears to be a cobalamin-containing protein, which is oxygen sensitive. The other enzyme (Co-methyl-5-hydroxybenzimidazolylcobamide: HS-CoM methyltransferase) was purified. It is insensitive to oxygen and it transfers also the methylgroup from Co-methyl-5,6-dimethylbenzimidazolylcobamide to HS-CoM.

Journal ArticleDOI
TL;DR: This study indicates for the first time what vascular endothelial cells, derived from an obligate heterozygote, are (partly) deficient in cysthathionine synthase and are more susceptible to methionine‐ and homocystine‐mediated injury than normal endothelium cells.
Abstract: This report describes the isolation and culture of venous endothelial cells from the umbilical cord of an obligate heterozygote for homocystinuria. The effect of different sulphur-containing amino acids on the viability and function of these cells was studied and compared with cultured normal endothelial cells. When endothelial cells were cultured in the presence of methionine (10 mmol/l) or homocystine (10 mmol/l), differences occurred between the viability and function of the heterozygote and normal cells in terms of 51Cr release and ability to prevent platelet adherence. The Cr release corrected for spontaneous release increases for the heterozygote cells after incubation/for 21 h in the presence of methionine to 81.3% (control cells, range: 0-23.3%, n = 5) and in the presence of homocystine to 141% (control cells, range: 13.5-55.2%, n = 5). The total number of platelets that adhere to confluent monolayers increases for heterozygote cells cultured in the presence of methionine to 0.98 X 10(7) platelets cm-2 (normal cells, range: 0.56-0.72 X 10(7) platelets cm-2) and in the presence of homocystine to 1.41 X 10(7) platelets cm-2 (normal cells, range: 0.94-1.06 X 10(7) platelets cm-2). Both normal and control cells were sensitive to homocysteine. This study/indicates for the first time what vascular endothelial cells, derived from an obligate heterozygote, are (partly) deficient in cysthathionine synthase and are more susceptible to methionine- and homocystine-mediated injury than normal endothelial cells. Consequently, in homocystinuria, due to dysfunction of the endothelial cells, toxic sulphur-containing amino acids may accumulate in these cells, causing injury of these cells.

Journal ArticleDOI
TL;DR: The physiological background of this endosymbiosis and its functioning in degradation processes in the anoxic environment are discussed.
Abstract: Fluorescent bacteria were demonstrated to be abundantly spread as single cells throughout the cytoplasm of the giant amoeba Pelomyxa palustris, the sapropelic ciliate Metopus striatus and six other anaerobic protozoa examined. The endosymbionts of P. palustris and M. striatus were identified as methanogenic bacteria on the basis of the presence of the deazaflavin coenzyme F420 and the pterin compound F342. Moreover individuals of P. palustris produced methane over a long period of incubation. The number of methanogenic bacteria was above 1010 cells/ml protozoal cytoplasm. Two types of methanogenic bacteria together with unidentified thick bacteria were found in P. palustris. The physiological background of this endosymbiosis and its functioning in degradation processes in the anoxic environment are discussed.

Journal ArticleDOI
TL;DR: In this paper, an attempt was made to show that audio-visual feedback is more effective in intonation learning than auditory feedback, while practice time did not seem to be a major factor.
Abstract: A description is given of an experiment in which an attempt was made to show that audio-visual feedback is more effective in intonation learning than auditory feedback. The factors in the experiment were feedback mode and practice time. The results showed a significant effect of audio-visual feedback over auditory feedback, whereas practice time did not seem to be a major factor. Feedback modality was shown to influence learning behavior. -

Journal ArticleDOI
TL;DR: The alpha 2- and beta 2-character of the presynaptic receptors matches that of the corresponding extrajunctional receptors, which indicates that a circulating catecholamine, namely epinephrine, is involved in the regulation of adrenergic transmitter release.

Journal ArticleDOI
TL;DR: The Nijmegen Breakage Syndrome is a new chromosomal instability disorder different from ataxia telangiectasia (AT), which means that NBS and AT, which also have similar chromosomal characteristics, must be closely related.
Abstract: The Nijmegen Breakage Syndrome (NBS) is a new chromosomal instability disorder different from ataxia telangiectasia (AT) and other chromosome-breakage syndromes. Cells from an NBS patient appeared hypersensitive to X-irradiation. X-rays induced significantly more chromosomal damage in NBS lymphocytes and fibroblasts than in normal cells. The difference was most pronounced after irradiation in G2. Further, NBS fibroblats were more readily killed by X-rays than normal fibroblasts. In addition, the DNA synthesis in NBS cells was more resistant to X-rays and bleomycin than that in normal cells. The reaction of NBS cells to X-rays and bleomycin was similar to that of cells from patients with ataxia telangiectasia. Our results indicate that NBS and AT, which also have similar chromosomal characteristics, must be closely related.

Journal ArticleDOI
TL;DR: In this article, a calculation scheme that establishes the transfer function of a thickness-mode piezoelectric transducer is described, and a computer program enables flexible manipulation of the design parameters that can be inserted are the properties of the piezo-material, the quarter-wavelength layer(s), the backing load and the electrical tuning and matching.


Journal ArticleDOI
TL;DR: The hairpin-to-coil equilibrium of the hexadecadeoxynucleotide d(ATCCTATTTTTAGGAT) was extensively studied by means of NMR, T-jump and UV, yielding a consistent picture of the dynamical behavior of this hairpin structure.
Abstract: The hairpin-to-coil equilibrium of the hexadecadeoxynucleotide d(ATCCTATTTTTAGGAT) was extensively studied by means of NMR, T-jump and UV. The thermodynamic and kinetic parameters for this equilibrium were determined, yielding a consistent picture of the dynamical behavior of this hairpin structure, which is shown to be a clear example of a situation in which the linebroadening of the imino proton resonances is not determined by the lifetime of the double helix. A comparative study of the homologous hairpins in which the size of the loop was elongated from 4 to 7 thymidine residues shows a monotonous decrease in Tm for the hairpin-to-coil transitions. This finding is in contrast with the view that the stability of hairpins reaches a maximum with a loop size of 6-7 residues. The NMR results indicate that the accessibility of the thymine bases in the loop towards solvent molecules or complementary nucleotides greatly depends on the size of the loop.

Journal ArticleDOI
TL;DR: A parallel processing model is suggested in which only the first unit is completely preprogrammed before the go signal and in which succeeding elements are programmed during the execution of preceding ones.

Journal ArticleDOI
TL;DR: It is concluded that serotoninergic systems in this region may influence the activity of these associated structures in a diffuse non-synaptic manner.

Journal ArticleDOI
TL;DR: Diffusion of calcium, cadmium and mercury was studied in a solution of mucus from rainbow trout and the significance of the results for uptake of these metals via the gills is discussed.

Journal ArticleDOI
TL;DR: The analysis of movement times for separate letter strokes revealed a process that involves the unpacking of later strokes during the execution of earlier ones, consistent with a three-stage model of complex motor behavior.