Showing papers by "University of Amsterdam published in 1996"
TL;DR: In patients with proximal-vein thrombosis, treatment with low-molecular-weight heparin at home is feasible, effective, and safe.
Abstract: Background An intravenous course of standard (unfractionated) heparin with the dose adjusted to prolong the activated partial-thromboplastin time to a desired length is the standard initial in-hospital treatment for patients with deep-vein thrombosis, but fixed-dose subcutaneous low-molecular-weight heparin appears to be as effective and safe. Because the latter treatment can be given on an outpatient basis, we compared the two treatments in symptomatic outpatients with proximal-vein thrombosis but no signs of pulmonary embolism. Methods We randomly assigned patients to adjusted-dose intravenous standard heparin administered in the hospital (198 patients) or fixed-dose subcutaneous low-molecular-weight heparin administered at home, when feasible (202 patients). We compared the treatments with respect to recurrent venous thromboembolism, major bleeding, quality of life, and costs. Results Seventeen of the 198 patients who received standard heparin (8.6 percent) and 14 of the 202 patients who received low-m...
1,070 citations
TL;DR: In this article, the authors studied extra-receptive field contextual modulation in area V1 of awake, behaving macaque monkeys and found that contextual modulation correlated with perceptual experience of both binocularly rivalrous texture displays and of displays with a simple example of surface occlusion.
Abstract: We studied extra-receptive field contextual modulation in area V1 of awake, behaving macaque monkeys. Contextual modulation was studied using texture displays in which texture covering the receptive field (RF) was the same in all trials, but the perceptual context of this texture could vary depending on the configuration of extra-RF texture elements. We found robust contextual modulation when disparity, color, luminance, and orientation cues variously defined a textured figure centered on the RF of V1 neurons. We found contextual modulation to have a spatial extent of ;8 to 10° diameter parafoveally. Contextual modulation correlated with perceptual experience of both binocularly rivalrous texture displays and of displays with a simple example of surface occlusion. We found contextual modulation in V1 to have a characteristic latency of 80‐100 msec after stimulus onset, potentially allowing feedback from extrastriate areas to underlie to this effect.
857 citations
Book•
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TL;DR: N- systems and H-systems and Gentzen systems, proof theory of arithmetic, second-order logic, and solutions to selected exercises.
Abstract: This introduction to the basic ideas of structural proof theory contains a thorough discussion and comparison of various types of formalization of first-order logic. Examples are given of several areas of application, namely: the metamathematics of pure first-order logic (intuitionistic as well as classical); the theory of logic programming; category theory; modal logic; linear logic; first-order arithmetic and second-order logic. In each case the aim is to illustrate the methods in relatively simple situations and then apply them elsewhere in much more complex settings. There are numerous exercises throughout the text. In general, the only prerequisite is a standard course in first-order logic, making the book ideal for graduate students and beginning researchers in mathematical logic, theoretical computer science and artificial intelligence. For the new edition, many sections have been rewritten to improve clarity, new sections have been added on cut elimination, and solutions to selected exercises have been included.
808 citations
TL;DR: The results suggest that further use of cA2 in MS is not warranted and that studies of other agents that antagonize TNF alpha should be carried out with frequent monitoring of gadolinium-enhanced MRIs.
Abstract: There is evidence that treatment with an antibody to tumor necrosis factor alpha (TNF alpha) improves an animal model of multiple sclerosis (MS) and is beneficial in two systemic inflammatory disease in humans, but there are no reports about anti-TNF treatment of MS. Therefore, we treated two rapidly progressive MS patients with intravenous infusions of a humanized mouse monoclonal anti-TNF antibody (cA2) in an open-label phase I safety trial and monitored their clinical status, gadolinium-enhanced brain magnetic resonance imaging (MRI), and peripheral blood and cerebrospinal fluid (CSF) immunologic status. We did not notice any clinically significant neurologic changes in either patient. The number of gadolinium-enhancing lesions increased transiently after each treatment in both patients. CSF leukocyte counts and IgG index increased after each treatment. The transient increase in the number of gadolinium-enhancing lesions that followed each infusion of cA2 together with the increase in cells and immunoglobulin in the CSF of each patient suggest that the treatment caused immune activation and an increase in disease activity. These results suggest that further use of cA2 in MS is not warranted and that studies of other agents that antagonize TNF alpha should be carried out with frequent monitoring of gadolinium-enhanced MRIs.
714 citations
TL;DR: The results suggest that G4.5 is the genetic locus responsible for the Barth syndrome, and introduces stop codons in the open reading frame interrupting translation of most of the putative proteins.
Abstract: Barth syndrome is a severe inherited disorder, often fatal in childhood, characterized by cardiac and skeletal myopathy, short stature and neutropenia. The disease has been mapped to a very gene-rich region in distal portion of Xq28. We now report the identification of unique mutations in one of the genes in this region, termed G4.5, expressed at high level in cardiac and skeletal muscle. Different mRNAs can be produced by alternative splicing of the primary G4.5 transcript, encoding novel proteins that differ at the N terminus and in the central region. The mutations introduce stop codons in the open reading frame interrupting translation of most of the putative proteins (which we term 'tafazzins'). Our results suggest that G4.5 is the genetic locus responsible for the Barth syndrome.
686 citations
TL;DR: In this paper, the authors present a taxonomy of theories of insight in problem-solving, including the puzzle-problem approach, the creation-based approach, and the great-mind approach.
678 citations
TL;DR: In this paper, personal initiative, a concept akin to entrepreneurship and organizational spontaneity, was compared in East and West Germany and the differences were hypothesized to be the results of occupational socialization, particularly of work control and complexity rather than of a selection effect.
Abstract: Personal initiative, a concept akin to entrepreneurship and organizational spontaneity, was compared in East and West Germany. Differences were hypothesized to be the results of occupational socialization, particularly of work control and complexity, rather than of a selection effect. A representative longitudinal study was conducted in the East and a cross-sectional study in the West. Lower initiative at work was found in the East; control and complexity affected changes in initiative. The results speak for socialization and against selection.
660 citations
TL;DR: A sudden and sharp rise in the C-14 content of the atmosphere, which occurred between ca. 850 and 760 calendar yr BC (ca. 2750-2450 BP on the radiocarbon time-scale), was contemporaneous with an abrupt climate change as discussed by the authors.
Abstract: A sudden and sharp rise in the C-14 content of the atmosphere, which occurred between ca. 850 and 760 calendar yr BC (ca. 2750-2450 BP on the radiocarbon time-scale), was contemporaneous with an abrupt climate change. In northwest Europe (as indicated by palaeoecological and geological evidence) climate changed from relatively warm and continental to oceanic. As a consequence, the ground-water table rose considerably in certain low-lying areas in The Netherlands. Archaeological and palaeoecological evidence for the abandonment of such areas in the northern Netherlands is interpreted as the effect of a rise of the water table and the extension of fens and bogs. Contraction of population and finally migration from these low-lying areas, which had become marginal for occupation, and the earliest colonisation by farming communities of the newly emerged salt marshes in the northern Netherlands around 2550 BP, is interpreted as the consequence of loss of cultivated land. Thermic contraction of ocean water and/or decreased velocity and pressure on the coast by the Gulf Stream may have caused a fall in relative sea-level rise and the emergence of these salt marshes. Evidence for a synchronous climatic change elsewhere in Europe and on other continents around 2650 BP is presented. Temporary aridity in tropical regions and a reduced transport of warmth to the temperate climate regions by atmospheric and/or oceanic circulation systems could explain the observed changes. As yet there is no clear explanation for this climate change and the contemporaneous increase of C-14 in the atmosphere. The strategy of C-14 wiggle-match dating can play an important role in the precise dating of organic deposits, and can be used to establish possible relationships between changing C-14 production in the atmosphere, climate change, and the impact of such changes on hydrology, vegetation, and human communities.
603 citations
TL;DR: In this article, the authors introduce the framework of update semantics and explain what kind of semantic phenomena may successfully be analyzed in it and give a detailed analysis of one such phenomenon: default reasoning.
Abstract: The aim of this paper is twofold: (i) to introduce the framework of update semantics and to explain what kind of semantic phenomena may successfully be analysed in it: (ii) to give a detailed analysis of one such phenomenon: default reasoning.
569 citations
TL;DR: The reliability and validity of the RAND 36-Item Health Survey 1.0 were investigated in a population sample of 1,063 inhabitants of a Dutch township and there is a need for further studies investigating its factor structure and cross-cultural equivalence.
Abstract: The reliability and validity of the RAND 36-Item Health Survey 1.0 were investigated in a population sample of 1,063 inhabitants of a Dutch township, all age 17or older. Confirmatory factor analysisonly partly supported the internal structure of the RAND 36-Item Health Survey 1.0. The internal consistency of the instrument was high. Pointing to high convergent validity, a multitrait-multimelhod matrix revealed that the RAND-36 scales showed higher correlations with corresponding scales from other instruments than with noncorresponding scales. However, indicating low discriminant validity, some of these correlations did not exceed the intercorrelations among the RAND-36 scales. Multivariate analysis of variance (MANOVA) showed significant effects of age for physical functioning, role limitations (physical problem), general health perception and pain, and significant effects of education on physical functioning and general health perception. Significant sex differences were found for mental health only. The results of this study on the psychometric properties of the RAND 36-Item Health Survey 1.0 seem promising. There is a need for further studies investigating its factor structure and cross-cultural equivalence.
496 citations
TL;DR: Bruce A. Averill was born in Ohio but grew up in New England and received a B.S. in chemistry from Michigan State University in 1969, followed by a Ph.D. in inorganic chemistry with Dick Holm at M.I.T., where he was an NSF predoctoral fellow.
Abstract: The inorganic nitrogen cycle (Figure 1) consists of several linked biological processes and one abiological process, the reaction of N2 and O2 in lightning discharges and internal combustion engines to produce NOx and, ultimately, nitrate. All of the processes except nitrogen fixation involve reduction or oxidation of species containing N-O bonds of order greater than 1, such as NO3, NO2, NO, and N2O. Denitrification is the anaerobic use by bacteria of nitrogen oxide species as terminal electron acceptors in place of O2. It is important because it constitutes the only process that returns large amounts of fixed nitrogen to the atmosphere, thereby completing the terrestrial nitrogen cycle (Figure 1). It is also important commercially in that denitrification, by itself or in combination with nitrification, can result in the loss of up to 30% of fixed nitrogen fertilizer.3 Further, denitrification is a “leaky” process under many conditions, resulting in the release of large amounts of N2O, a greenhouse gas that is also implicated in atmospheric ozone depletion,4 into the atmosphere. Denitrifiers are potentially of great importance in bioremediation efforts,5 since dissolved nitrate concentrations are often easier to control than are oxygen concentrations. In addition, denitrifiers have important potential applications in wastewater remediation, as evidenced by the use of immobilized nitrate, nitrite, and nitrous oxide reductase enzymes for electrochemical6 or biochemical7 removal of nitrate from water. Finally, the well-studied enzymes of denitrification provide potential structural and spectroscopic models for mammalian enzymes that produce and utilize NO in a variety of signal transduction pathways.8 Denitrification is a basic physiological process that is crucial for energy generation in the survival of a variety of bacteria.2 Denitrifying bacteria occupy a wide range of natural habitats, including soil, water, foods, and the digestive tract.9-11 Although these organisms prefer oxygen as an electron acceptor, in the absence of oxygen they can obtain energy from electron transport phosphorylation coupled to the reduction of nitrogen oxide species (NO3, NO2, NO, N2O). Before proceeding further, it is important to distinguish denitrification from two other physiological * Phone: 31-20-525-5045. Fax: 31-20-525-5124. E-mail: BAA@ CHEM.UVA.NL. Bruce A. Averill was born in Ohio in 1948 but grew up in New England. He received a B.S. in chemistry from Michigan State University in 1969. This was followed in 1973 by a Ph.D. in inorganic chemistry with Dick Holm at M.I.T., where he was an NSF predoctoral fellow. He subsequently spent 3 years learning biochemistry on NSF and NIH postdoctoral fellowships with Bob Abeles at Brandeis University and Bill Orme-Johnson at the University of Wisconsin, Madison. In 1976, he returned as an assistant professor of chemistry to Michigan State University, where he was named an Alfred P. Sloan Foundation Fellow and promoted to associate professor in 1981. The next year, he moved to the University of Virginia, where he was promoted to professor of chemistry in 1988. During his time at Virginia, the focus of his research shifted more toward studies of metalloenzymes. In 1994, he moved to the E. C. Slater Institute of the University of Amsterdam as a professor of biochemistry, specializing in biocatalysis. His research now focuses on the structure and mechanism of iron-containing phosphatases and the enzymes of denitrification.
TL;DR: Using targeted genedisruption, it is found that Sox-4−/− embryos succumb to circulatory failure at day E14, a result of impaired development of the endocardial ridges into the semilunar valves and the outlet portion of the muscular ventricular septum.
Abstract: A striking example of the relationship between regulation of transcription and phenotype is the central role of the Y-chromosomal gene Sry in mammalian sex determination. Sry is the founding member of a large family of so-called Sox genes. During murine embryogenesis, the transcriptional activator Sox-4 is expressed at several sites, but in adult mice expression is restricted to immature B and T lymphocytes. Using targeted gene distruption, we have found that SOX-4(-/-) embryos succumb to circulatory failure at day E14. This was a result of impaired development of the endocardial ridges (a specific site of Sox-4 expression) into the semilunar valves and the outlet portion of the muscular ventricular septum. The observed range of septation defects is known as 'common arterial trunk' in man. We studied haemopoiesis in lethally irradiated mice reconstituted with SOX-4(-/-) fetal liver cells and found that a specific block occurred in B-cell development at the pro-B cell stage. In line with this, the frequency and proliferative capacity of IL-7-responsive B cell progenitors in fetal liver were severely decreased in vitro.
TL;DR: In this article, a new approach towards resonant interaction between classical light and matter is presented, where the interaction between light and material is considered from three different points of view: the light picture where the material degrees of freedom have been integrated out, and leaving one with scattering theory, the matter picture (where the radiative degree of freedom has been eliminated and providing one essentially with atomic physics).
TL;DR: In this article, regret was used to predict regret-minimizing gambles in both gains and losses and in both relatively high risk and relatively low risk pairs of gambles.
TL;DR: In this article, an experimental analysis of voluntary, binary contributions for step-level public goods is presented, where independent information is obtained on individual value orientation and expectations about the behavior of other subjects using incentive compatible mechanisms.
Abstract: An experimental analysis of voluntary, binary contributions for step-level public goods is presented. Independent information is obtained on individual value orientation and expectations about the behavior of other subjects using incentive compatible mechanisms. The effects of increasing payoffs for the public good and of decreasing groupsize are investigated. Attention is focused on the determination of expectations, the use of expectations when deciding on behavior, and differences in expectations and behavior between individuals with different value orientations.
TL;DR: The isolation of a cDNA representing the FAA gene is reported, following an expression cloning method similar to the one used to clone the FAC gene.
Abstract: Fanconi anaemia (FA) is an autosomal recessive disorder characterized by a diversity of clinical symptoms including skeletal abnormalities, progressive bone marrow failure and a marked predisposition to cancer1–4. FA cells exhibit chromosomal instability and hyper-responsiveness to the clastogenic5 and cytotoxic6 effects of bifunctional alkylating (cross-linking) agents, such as diepoxybutane (DEB) and mitomycin C (MMC). Five complementation groups (A–E) have been distinguished on the basis of somatic cell hybridization experiments7–9, with group FA-A accounting for over 65% of the cases analysed10,11. A cDNA for the group C gene (FAC) was reported12 and localized to chromosome 9q22.3 (ref. 8). Genetic map positions were recently reported for two more FA genes, FAA (16q24.3)13 and FAD (3p22–26)14. Here we report the isolation of a cDNA representing the FAA gene, following an expression cloning method similar to the one used to clone the FAC gene12. The 5.5-kb cDNA has an open reading frame of 4,368 nucleotides. In contrast to the 63-kD cytosolic protein encoded by the FAC gene, the predicted FAA protein (Mr 162,752) contains two overlapping bipartite nuclear localization signals and a partial leucine zipper consensus, which are suggestive of a nuclear localization.
TL;DR: The results confirm the importance of in-group norms and demonstrate differences between experimental and natural groups in the applicability of competing social identity and self-categorization principles.
Abstract: Manipulation of in-group and out-group norms of discrimination and fairness allowed for the operation of competing social identity principles concerning in-group bias, conformity, and group distinctiveness. The combined effects of these principles on in-group bias were first examined in a modified minimal-group setting (Study 1). Results demonstrated that participants' allocation strategies were in accord with the in-group norm. Furthermore, dissimilar norms resulted in greater use of positive differentiation allocation strategies. However, in natural groups (Study 2), more in-group bias was found when both group norms were similar and discriminatory. The results confirm the importance of in-group norms and demonstrate differences between experimental and natural groups in the applicability of competing social identity and self-categorization principles.
TL;DR: The loss of chromosome 1p is a strong prognostic factor in patients with neuroblastoma, independently of age and stage, and reliably identifies patients at high risk in stages I, II, and IVS, which are otherwise clinically favorable.
Abstract: Background Neuroblastoma is a childhood tumor derived from cells of the neural crest, with a widely variable outcome. Differences in the behavior and prognosis of the tumor suggest that neuroblastoma can be divided into several biologic subgroups. We evaluated the most frequent genetic abnormalities in neuroblastoma to determine their prognostic value. Methods We used Southern blot analysis to study the allelic loss of chromosomes 1p, 4p, 11q, and 14q, the duplication of chromosome 17q, and the amplification of the N-myc oncogene in 89 neuroblastomas. We also determined the nuclear DNA content of the tumor cells. Results Allelic loss of chromosome 1p, N-myc amplification, and extra copies of chromosome 17q were significantly associated with unfavorable outcomes. In a multivariate analysis, loss of chromosome 1p was the most powerful prognostic factor. It provided strong prognostic information when it was included in multivariate models containing the prognostic factors of age and stage or serum ferritin l...
TL;DR: If the level of virus replication can be similarly reduced in 3TC‐treated patients that develop drug‐resistant HIV‐1 variants, this may be of considerable clinical benefit.
Abstract: Human immunodeficiency virus type 1 (HIV-1) variants with resistance mutations in the reverse transcriptase (RT) gene appear during drug therapy with the nucleoside analogue 2',3'-dideoxy-3'-thiacytidine (3TC). These resistance mutations alter the methionine (Met) residue of the conserved YMDD motif, which is part of the catalytic core of the RT enzyme. Isoleucine (Ile) variants are initially observed, followed by the appearance and eventual outgrowth of viruses encoding valine (Val). Similar replication kinetics were measured for wild-type and 3TC-resistant HIV-1 viruses in tissue culture infections of a T cell line, but we measured reduced polymerase activity for the two mutant RT enzymes compared with the wild-type enzyme (Ile = 43% and Val = 67%). Gel analysis of the reverse transcription products revealed that both 3TC-resistant RT mutants produce significantly shorter cDNA molecules than the wild-type enzyme [Met (wt)>Val>Ile], indicating that 3TC-resistant RT polymerases are less processive enzymes. Interestingly, these enzyme defects were more pronounced under limiting dNTP concentrations and we therefore assayed virus replication in primary cells that contain relatively low dNTP levels. Under these conditions, we measured significantly reduced replication kinetics for the 3TC-resistant HIV-1 variants [Met (wt)>Val>Ile]. If the level of virus replication can be similarly reduced in 3TC-treated patients that develop drug-resistant HIV-1 variants, this may be of considerable clinical benefit.
TL;DR: In this paper, the authors reviewed current knowledge on the risk of ectopic pregnancy (EP), with the exception of contraceptive methods, and found that previous EP, previous tubal surgery, documented tubal pathology, and in utero diethylstilbestrol (DES) exposure were associated strongly with the occurrence of EP.
Book•
01 Jan 1996TL;DR: In this paper, the authors examine the lives of those who, pushed out of the agrarian labour market, depend on casual work and argue that their identity is shaped by both class and caste relations and nothing of significance has been achieved to improve their quality of life.
Abstract: In a penetrating anthropological study of the working poor in India, Jan Breman examines the lives of those who, pushed out of the agrarian labour market, depend on casual work. Beginning his local-level research in two villages in south Gujarat, the author discusses the mobilisation of casual labour, which is hired and fired according to the need of the moment, and transferred for the duration of the job to destinations far away from the home area. His case-study reveals that the circulation of labour is indicative of an employment pattern which dominates both the rural and urban economy of large parts of South Asia. Elaborating on the social profile of the work migrants, the author argues that their identity is shaped by both class and caste relations and, despite action by state agencies, nothing of significance has been achieved to improve their quality of life.
TL;DR: This book aims to provide a chronology of events leading up to and including the invention of the atomic bomb in Japan in 1945 and its use in the bombings of Hiroshima and Nagasaki in 1945.
Abstract: Ben Distel,* Ralf Erdmann, ¢ Stephen J. Gould, ~ Gtinter Blobel,I Denis I. Crane, I James M. Cregg,** Gabriele Dodt,* Yukio Fujiki, *~ Joel M. Goodman, ~ Wilhelm W. Just, D Jan A.K.W. Kiel, 11 Wolf-Hubert Kunau,* Paul B. Lazarow,*** Guy P. Mannaerts, ~*~ Hugo W. Moser, §~§ Takashi Osumi, Richard A. Rachubinski,11~l Adelbert Roscher,**** Suresh Subramani, **¢* Henk F. Tabak,* Toshiro Tsukamoto,llllll David Valle, ~ § Ida van der Klei, ~11I Paul P. van Veldhoven, ¢** and Marten Veenhuis ~I~I
Book•
01 Jan 1996TL;DR: (Artificial) neural networks are information processing systems, whose structure and operation principles are inspired by the nervous system and the brain of animals and humans.
Abstract: (Artificial) neural networks are information processing systems, whose structure and operation principles are inspired by the nervous system and the brain of animals and humans. They consist of a large number of fairly simple units, the so-called neurons, which are working in parallel. These neurons communicate by sending information in the form of activation signals, along directed connections, to each other.
TL;DR: In this paper, the Amsterdam Preoperative Anxiety and Information Scale (APAIS) was used to assess patients' anxiety level and information requirement in the pre-operative phase, and the results showed that women were more anxious than men; patients with high information requirement also had a high level of anxiety; and patients who had never undergone an operation had a higher information requirement than those who had.
Abstract: The purpose of the present study was to assess patients' anxiety level and information requirement in the preoperative phase. During routine preoperative screening, 320 patients were asked to assess their anxiety and information requirement on a six-item questionnaire, the Amsterdam Preoperative Anxiety and Information Scale (APAIS). Two hundred patients also completed Spielberger's State-Trait Anxiety Inventory (STAI-State). Patients were able to complete the questionnaire in less than 2 min. On factor analysis, two factors emerged clearly: anxiety and the need for information. The anxiety scale correlated highly (0.74) with the STAI-State. It emerged that 32% of the patients could be considered as "anxiety cases" and over 80% of patients have a positive attitude toward receiving information. Moreover, results demonstrated that 1) women were more anxious that men; 2) patients with a high information requirement also had a high level of anxiety; 3) patients who had never undergone an operation had a higher information requirement than those who had. The APAIS can provide anesthesiologists with a valid, reliable, and easily applicable instrument for assessing the level of patients' preoperative anxiety and the need for information.
TL;DR: The highly similar results in the Dutch and Scottish sample suggest that the portrayal of fatigue using the MFI-20 is quite robust, and the psychometric properties of the multidimensional fatigue inventory are established further in cancer patients.
Abstract: In this paper the psychometric properties of the multidimensional fatigue inventory (MFI-20) are established further in cancer patients. The MFI is a 20-item self-report instrument designed to measure fatigue. It covers the following dimensions: general fatigue, physical fatigue, reduced activity, reduced motivation and mental fatigue. The instrument was used in a Dutch and Scottish sample of cancer patients receiving radiotherapy. The dimensional structure was assessed using confirmatory factor analyses (Lisrel's unweighted least-squares method). The hypothesised five-factor model appeared to fit the data in both samples (adjusted goodness of fit; AGFI: 0.97 and 0.98). Internal consistency of the separate scales was good in both the Dutch and Scottish samples with Cronbach's alpha coefficients ranging from 0.79 to 0.93. Construct validity was assessed by correlating the MFI-20 to activities of daily living, anxiety and depression. Significant relations were assumed. Convergent validity was investigated by correlating the MFI scales with a visual analogue scale measuring fatigue and with a fatigue-scale derived from the Rotterdam Symptom Checklist. Results support the validity of the MFI-20. The highly similar results in the Dutch and Scottish sample suggest that the portrayal of fatigue using the MFI-20 is quite robust.
TL;DR: This is the first study to show associations between TNF haplotypes and TNFα and LTα secretion when T‐cell stimulators are used, and will contribute to define disease heterogeneity in IBD and may be of relevance for understanding the pathogenesis of autoimmune diseases.
Abstract: The genes for tumour necrosis factor alpha (TNF alpha) and lymphotoxin alpha (LT alpha; TNF beta) are tandemly arranged in the central region of the MHC. They may, therefore, be of importance for the aetiology of MHC-associated diseases. The authors have prospectively studied the secretion of TNF alpha and LT alpha in relation to polymorphisms at positions -308 and -238 in the TNF alpha gene (TNFA), and two polymorphisms in the first intron of the LT alpha gene (LTA), as well as HLA-DR in 30 patients with chronic inflammatory bowel diseases (IBD) and 12 healthy controls. In the Dutch population, the alleles of these four polymorphisms are present in only five combinations, called TNF-haplotypes: TNF-C, -E, -H, -I, and -P. Significant associations between TNF haplotypes and TNF alpha and LT alpha secretion were found when PBMC were cultured with T-cell activators, irrespective of disease. Mean TNF alpha secretion of individuals carrying the HLA-DR3 associated TNF-E haplotype was significantly higher, as compared to individuals without this haplotype (26 441 pg/ml versus 19 629 pg/ml; P = 0.014). Individuals carrying the TNF-C haplotype produced the lowest amount of TNF alpha (17 408 pg/ml; P=0.022). The TNF-C and TNF-E haplotypes differ only at position -308 in the promoter of TNFA. Individuals carrying the HLA-DR1 associated TNF-I haplotype produced significantly less LT alpha when compared to those who lack this haplotype (1979 pg/ml versus 3462 pg/ml; P = 0.006). As the TNF-I haplotype is also associated with low TNF alpha secretion, this haplotype thus defines a 'low secretor phenotype'. In conclusion, this is the first study to show associations between TNF haplotypes and TNF alpha and LT alpha secretion when T-cell stimulators are used. These findings will contribute to define disease heterogeneity in IBD and may be of relevance for understanding the pathogenesis of autoimmune diseases.
TL;DR: It is suggested that a superimposed high‐frequency train of stimuli is a more sensitive indicator of central activation failure during isometric MVCs compared with either the superimposed single or double stimuli methods.
Abstract: Muscle fatigue or neuromuscular disease may result in central activation failure during maximal voluntary contractions (MVCs). Superimposition of an electrically stimulated contraction during an MVC has been used to detect central activation failure. To determine the most sensitive means of quantitating central activation failure using this technique, we compared the increment in isometric force from single, double, and high-frequency trains (50 Hz, 500 or 1000 ms) of stimuli of the peroneal nerve imposed during three separate MVCs of the dorsiflexor muscles. Completeness of activation was quantitated with the central activation ratio (CAR) = MVC/(MVC + stimulated force). Comparisons were made of the CARs of three groups of subjects during the three stimulation conditions: 7 healthy subjects, 13 patients with amyotrophic lateral sclerosis, and 5 healthy subjects after fatiguing exercise. For all three groups, the CAR was significantly lower during the train of stimuli condition (means = 0.76-0.89) compared with either the single or double stimuli conditions (means = 0.96-1.00). The results suggest that a superimposed high-frequency train of stimuli is a more sensitive indicator of central activation failure during isometric MVCs compared with either the superimposed single or double stimuli methods.
TL;DR: Findings indicate that rest-activity rhythm disturbances may improve by increasing environmental light and daytime activity, an assumption for which empirical evidence has recently been published.
TL;DR: The calculations show the feasibility of optical manipulations of trapped Bose condensates through a light-induced change in the mean field interaction between atoms, which is illustrated for {sup 7}Li.
Abstract: We develop the idea of manipulating optically the scattering length $a$ in low-temperature atomic gases. If the incident light is close to resonance with one of the bound $p$ levels of electronically excited molecules, virtual radiative transitions of a pair of interacting atoms to this level can significantly change the value and even reverse the sign of $a$. The decay of the gas due to photon recoil and due to photoassociation can be minimized by selecting the frequency detuning and the Rabi frequency. Our calculations show the feasibility of optical manipulations of trapped Bose condensates through a light-induced change in the mean field interaction between atoms, which is illustrated for ${}^{7}\mathrm{Li}$.