Showing papers by "University of Birmingham published in 1993"
TL;DR: The best understood form of long-term potentiation is induced by the activation of the N-methyl-d-aspartate receptor complex, which allows electrical events at the postsynaptic membrane to be transduced into chemical signals which, in turn, are thought to activate both pre- and post Synaptic mechanisms to generate a persistent increase in synaptic strength.
Abstract: Long-term potentiation of synaptic transmission in the hippocampus is the primary experimental model for investigating the synaptic basis of learning and memory in vertebrates. The best understood form of long-term potentiation is induced by the activation of the N-methyl-D-aspartate receptor complex. This subtype of glutamate receptor endows long-term potentiation with Hebbian characteristics, and allows electrical events at the postsynaptic membrane to be transduced into chemical signals which, in turn, are thought to activate both pre- and postsynaptic mechanisms to generate a persistent increase in synaptic strength.
11,123 citations
TL;DR: It is now widely accepted that apoptosis is a genedirected process and can be seen, alongside more familiar gene-directed processes like differentiation, as part of the repertoire available to the cell to respond to external and internal stimuli.
940 citations
TL;DR: It is proposed that MIP-1β and other cytokines with glycosaminoglycan-binding sites will bind to and be presented by endothelial proteoglycans to trigger adhesion selectively not only of lymphocyte subsets, but also of other cell types.
Abstract: Lymphocyte migration from blood into tissue depends on integrin-mediated adhesion to endothelium. Adhesion requires not only integrin ligands on the endothelium, but also activation signals because T-cell integrins cannot bind well until they are activated. The physiological 'triggers' for T-cell adhesion are unknown, but cytokines may be good candidates as they are released during inflammation and trigger adhesion in neutrophils and monocytes. We have identified a cytokine, macrophage inflammatory protein-1 beta (MIP-1 beta), that induces both chemotaxis and adhesion of T cells; MIP-1 beta is most effective at augmenting adhesion of CD8+ T cells to the vascular cell adhesion molecule VCAM-1. We reasoned that, as cytokines in vivo will be rapidly washed away, MIP-1 beta might be bound to endothelial surfaces and so induce adhesion in its immobilized form. Here we show that: (1) MIP-1 beta is present on lymph node endothelium; (2) immobilized MIP-1 beta induces binding of T cells to VCAM-1 in vitro. MIP-1 beta was immobilized by binding to proteoglycan: a conjugate of heparin with bovine serum albumin and cellular proteoglycan CD44 were both effective. We propose that MIP-1 beta and other cytokines with glycosaminoglycan-binding sites will bind to and be presented by endothelial proteoglycans to trigger adhesion selectively not only of lymphocyte subsets, but also of other cell types.
888 citations
TL;DR: In this paper, a system for the automatic measurement of electrical resistivity pseudo-sections is described, which comprises a linear array of up to 32 electrodes connected through a multicore cable to a computer controlled switching module and a resistivity meter.
767 citations
TL;DR: (RS)-α-methyl-4-carboxyphenylglycine is a specific mGluR antagonist in the hippocampus and this compound is used to examine the nature of the involvement ofmGluRs in LTP, and it is shown that synaptic activation of mGLURs is necessary for the induction of both NMDA receptor-dependent and NMDA receptors-independent forms of LTP inThe hippocampus.
Abstract: Understanding the mechanisms of long-term potentiation (LTP) should provide insights into the molecular basis of learning and memory in vertebrates. Ionotropic glutamate receptors play a central role in LTP; AMPA (alpha-amino-3-hydroxy-5-methyl-4-isoxazolepropionate) receptors and NMDA (N-methyl-D-aspartate) receptors mediate synaptic responses that are enhanced in LTP and, in addition, NMDA receptors are necessary for the induction of LTP in most pathways. There is also circumstantial evidence that metabotropic glutamate receptors (mGluRs) may be involved in LTP because the specific mGluR agonist aminocyclopentane dicarboxylate can augment tetanus-induced LTP2 and, under certain circumstances, can itself induce a slow-onset potentiation. But the absence of any effective mGluR antagonist has prevented the determination of whether mGluRs are involved in the induction of tetanus-induced LTP. We report here that (RS)-alpha-methyl-4-carboxyphenylglycine is a specific mGluR antagonist in the hippocampus and have used this compound to examine the nature of the involvement of mGluRs in LTP. We show that synaptic activation of mGluRs is necessary for the induction of both NMDA receptor-dependent and NMDA receptor-independent forms of LTP in the hippocampus.
717 citations
TL;DR: In this paper, immunolabeled human and mouse metaphase chromosomes with antibodies specific for the acetylated isoforms of histone H4 were labeled in regions corresponding to conventional R bands (regions enriched in coding DNA), except for a single chromosome in female cells.
711 citations
Book•
01 Jan 1993TL;DR: The overwintering locale - suitability and selection, as well as the stimuli controlling diapause and overwinters, are described.
Abstract: Foreword 1. Introduction 2. The overwintering locale - suitability and selection 3. The stimuli controlling diapause and overwintering 4. Insect cold-hardiness 5. Costs and benefits of overwintering 6. Prediction and control Bibliography Index.
451 citations
TL;DR: Residents of Bromsgrove, which is served by a traditional mental hospital, were slightly more tolerant than those living in Malvern, which has a community-based service, and has seen the closure of two mental hospitals in its vicinity during the last 10 years.
Abstract: A survey of attitudes to mental illness was conducted in a quota sample of about 2000 subjects in Malvern and Bromsgrove. Factor analysis showed three main components - benevolence, authoritarianism, and fear of the mentally ill. Residents of Bromsgrove, which is served by a traditional mental hospital, were slightly more tolerant than those living in Malvern, which has a community-based service, and has seen the closure of two mental hospitals in its vicinity during the last 10 years. The main demographic determinants of tolerance are age, education, occupation, and acquaintance with the mentally ill.
398 citations
TL;DR: A detailed review and chronological survey of the various techniques which have been used for the measurement of river bank erosion and channel change is presented in this article, where the techniques are classified according to the time scales involved (long, intermediate and short).
Abstract: A detailed review and chronological survey is presented of the various techniques which have been used for the measurement of river bank erosion and channel change. The techniques are classified according to the time scales involved (long, intermediate and short) and each is discussed with respect to accuracy and repeatability. The methods covered include sedimentological evidence, botanical evidence, historical sources, planimetric resurvey, repeated cross-profiling, erosion pins and terrestrial photogrammetry. Prospects for future developments are also discussed.
392 citations
TL;DR: Preliminary results on viral gene expression in HRS cells are extended by adopting polymerase chain reaction-based and in situ hybridization assays capable of detecting specific EBV latent transcripts diagnostic of the different possible forms of EBV latency.
Abstract: Epstein-Barr virus (EBV) is associated with a number of different human tumors and appears to play different pathogenetic roles in each case. Thus, immunoblastic B cell lymphomas of the immunosuppressed display the full pattern of EBV latent gene expression (expressing Epstein-Barr nuclear antigen [EBNA]1, 2, 3A, 3B, 3C, and -LP, and latent membrane protein [LMP]1, 2A, and 2B), just as do B lymphoblastoid cell lines transformed by the virus in vitro. In contrast, those EBV-associated tumors with a more complex, multistep pathogenesis show more restricted patterns of viral gene expression, limited in Burkitt's lymphoma to EBNA1 only and in nasopharyngeal carcinoma (NPC) to EBNA1 and LMP1, 2A, and 2B. Recent evidence has implicated EBV in the pathogenesis of another lymphoid tumor, Hodgkin's disease (HD), where the malignant Hodgkin's and Reed-Sternberg (HRS) cells are EBV genome positive in up to 50% of cases. Here we extend preliminary results on viral gene expression in HRS cells by adopting polymerase chain reaction-based and in situ hybridization assays capable of detecting specific EBV latent transcripts diagnostic of the different possible forms of EBV latency. We show that the transcriptional program of the virus in HRS cells is similar to that seen in NPC in several respects: (a) selective expression of EBNA1 mRNA from the BamHI F promoter; (b) downregulation of the BamHI C and W promoters and their associated EBNA mRNAs; (c) expression of LMP1 and, in most cases, LMP2A and 2B transcripts; and (d) expression of the "rightward-running" BamHI A transcripts once thought to be unique to NPC. This form of latency, consistently detected in EBV-positive HD irrespective of histological subtype, implies an active role for the virus in the pathogenesis of HD and also suggests that the tumor may remain sensitive to at least certain facets of the EBV-induced cytotoxic T cell response.
387 citations
TL;DR: In this article, it was shown that sphagnum moss peat, which is essentially oligotrophic, in concentrations ranging from 4 to 40 g/l can be used effectively to remove hexavalent chromium from aqueous solutions.
TL;DR: These findings provide the first direct evidence that mesenchymal as well as epithelial cells are involved in T-cell development, and suggest that their involvement is stage-specific and likely to be dependent on short-range or contact-mediated interactions.
Abstract: T lymphocytes are produced in the thymus from precursors originating in the haemopoietic tissues. On entering the thymus, they undergo a programme of proliferation, T-cell receptor (TCR) gene rearrangement, differentiation and repertoire selection. Although the thymus provides a unique environment for these events, the role of the thymic stroma in regulating specific developmental stages is not well understood. We therefore devised an in vitro system to study the role of individual thymic stromal components in T-cell development. We report here that the development of TCR-CD4-CD8-T-cell precursors into TCR+ cells expressing CD4 and/or CD8 requires the presence of both major histocompatibility complex class II+ epithelial cells and fetal mesenchyme. The requirement for mesenchymal support can be mapped to the initial stages of intrathymic development because the later stages of maturation, from double-positive CD4+CD8+ thymocytes into single-positive CD4+ or CD8+ cells, can be supported by epithelial cells alone. We also show that the requirement for mesenchymal cells can be met by cells of the fibroblast line 3T3 (but not by supernatants from these cells). To our knowledge, these findings provide the first direct evidence that mesenchymal as well as epithelial cells are involved in T-cell development, and suggest that their involvement is stage-specific and likely to be dependent on short-range or contact-mediated interactions.
10 Mar 1993-Nuclear Instruments & Methods in Physics Research Section A-accelerators Spectrometers Detectors and Associated Equipment
TL;DR: In this paper, the Birmingham positron camera was used for tracking positron-emitting particles within engineering structures, using particles typically 4 MBq (100 μCi) 18 F or 22 Na.
Abstract: The use of the Birmingham positron camera for tracking positron-emitting particles within engineering structures has been investigated, using particles containing typically 4 MBq (100 μCi) 18 F or 22 Na. An algorithm for discarding γ-ray trajectories corrupted by scattering, etc., and using the remaining trajectories to compute the particle's location in three dimensions has been developed, and its performance explained. A slowly moving particle can be located to within 1 mm several times per second, while a particle moving at 1 ms −1 can be located to within 5 mm 50 times per second, through a considerable thickness of surrounding material. An example of results obtained from tracking a particle in a rotating drum of powder illustrates the potential value of the technique.
TL;DR: Molecular analysis of the Norrie gene locus in a four generation FEVR family reveals a missense mutation in the highly conserved region of the NDP gene, suggesting that phenotypes of both XLFEVR and Norrie disease can result from mutations in the same gene.
Abstract: Familial exudative vitreoretinopathy (FEVR) is a hereditary disorder characterized by an abnormality of the peripheral retina. Both autosomal dominant (adFEVR) and X–linked (XLFEVR) forms have been described, but the biochemical defect(s) underlying the symptoms are unknown. Molecular analysis of the Norrie gene locus (NDP) in a four generation FEVR family (shown previously to exhibit linkage to the X–chromosome markers DXS228 and MAOA (Xp11.4–p11.3)) reveals a missense mutation in the highly conserved region of the NDP gene, which caused a neutral amino acid substitution (Leu124Phe), was detected in all of the affected males, but not in the unaffected family members, nor in normal controls. The observations suggest that phenotypes of both XLFEVR and Norrie disease can result from mutations in the same gene.
Book•
01 Dec 1993TL;DR: In this paper, the authors take a critical look at the field of strategic human resource management and in particular the debate about the strategic value of the human resource and identify the contribution as well as the problematic nature of the situational-contingency perspective.
Abstract: This paper takes a critical look at the field of strategic human resource management and in particular the debate about the strategic value of the human resource. We identify the contribution as well as the problematic nature of the situational-contingency perspective. Drawing from the strategic management literature and the concept of resource heterogeneity, we then posit a resource-capability view of the firm and argue that the mutually reinforcing interaction between the stock of knowledge, skills and expertise (resources) and the organizational routines and human resource policies and practices (capabilities) generates human resource competencies whose strategic value is realizable to the extent that they are linked with core competencies. We thus offer a reconceptualization of human resource competencies which goes beyond existing trait, behavioural and systems approaches. Finally, we identify the circumstances surrounding the generation and distribution of rents arising from the utilization of human resource competencies by drawing from transaction cost theory and industrial relations.
TL;DR: Data contrasting the processing of facial identity from static photographs, and facial expression from static and moving images, in two patients with face processing impairments are reported, indicating the separate encoding of expression from moving and static images.
TL;DR: The proportion of insects preferring the novel host has increased, in one case clearly because of genetic changes in the insect population, and this process is now starting to generate insects that refuse to accept their ancestral host, foreshadowing a new problem in conservation biology.
Abstract: RAPID evolution of host association is now occurring independently in two populations of the host-specialist butterfly Euphydryas editha, each of which has recently incorporated a novel host species into its diet. The reasons for these episodes of rapid evolution lie in human land use practices: logging in one case and cattle ranching in the other. In contrast to other insects that have used tolerance of human activities to expand their ranges into disturbed habitats1–3, these rare butterflies have remained at their original sites and evolved adaptations to the changes occurring at those sites. At both sites, the proportion of insects preferring the novel host has increased, in one case clearly because of genetic changes in the insect population. This process is now starting to generate insects that refuse to accept their ancestral host, foreshadowing a new problem in conservation biology. By adapting genetically to human-induced changes in their habitat, the insects risk becoming dependent on continuation of the same practices. This is a serious risk, because human cultural evolution can be even faster than the rapid genetic adaptation that the insects can evidently achieve.
TL;DR: The flux line lattice inside a single crystal of Bi2.15Sr1.95CaCu2O8+x has been observed using small-angle neutron diffraction.
Abstract: The flux line lattice inside a single crystal of Bi2.15Sr1.95CaCu2O8+x has been observed using small-angle neutron diffraction. The diffracted intensity goes rapidly to zero at a magnetic-field-dependent flux lattice melting temperature; this melting coincides with the appearance of finite resistance within the superconducting state. The flux lattice signal can also be made to disappear at low temperatures, by applying a sufficiently high field, probably because of the decomposition of flux lines into two-dimensional 'pancake' vortices.
TL;DR: In this paper, a connectionist model is proposed to perform visual search in parallel across a window defining the model′s functional field, where elements in the field are allowed to group, using simple principles of similarity and spatial proximity.
TL;DR: Sialylated carbohydrate on neutrophils appears essential for P-selectin-mediated adhesion, and a proportion of this ligand may be presented by L-selectIn, according to a novel technique that allows visualization of adhesion of flowing neutrophil to immobilized, activated platelets.
TL;DR: In this paper, the pulsed laser-photolysis (PLP), time-resolved laser-induced fluorescence (LIF) technique has been used to study the reactions of the CN radical with CH 4, C 2 H 6, C 2H 4 and C 3 H 6 at low and ultra-low temperatures.
TL;DR: The results suggest that evolution of a widespread and genetically stable virus such as EBV is influenced by pressure from MHC-restricted CTL responses.
Abstract: Cytotoxic T lymphocytes (CTLs) control viral infections by recognizing viral peptides presented by major histocompatibility complex (MHC) class I molecules. Human leukocyte antigen (HLA)-A11-restricted CTLs that recognize peptide residues 416 to 424 of the Epstein-Barr virus (EBV) nuclear antigen-4 frequently dominate EBV-induced responses in A11+ Caucasian donors. This epitope is conserved in type A EBV strains from Caucasians and central African populations, where A11 is relatively infrequent. However, strains from highly A11+ populations in New Guinea carry a lysine-to-threonine mutation at residue 424 that abrogates CTL recognition and binding of the peptide to nascent A11 molecules. The results suggest that evolution of a widespread and genetically stable virus such as EBV is influenced by pressure from MHC-restricted CTL responses.
TL;DR: 1S,3R-ACPD-induced LTP circumvents the need for the activation of NMDA receptors and is likely to involve both the stimulation of protein kinase C (PKC) and the release of Ca2+ from intracellular stores.
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TL;DR: In this article, the authors draw on media and marketing material to argue that by combining the myth of the return to "the golden age of travel" with that of images of a return to nature, the tourist is, willingly, being seduced into believing that they/we are in fact sophisticated, eco-sensitive travellers.
Abstract: The paper draws on media and marketing material to argue that by combining the myth of the return to ‘the golden age of travel’ with that of images of a ‘return to nature’, the ‘thinking’ tourist is, willingly, being seduced into believing that they/we are in fact sophisticated, eco-sensitive travellers. The corollory of this cosy conspiracy is that tourism products deemed acceptable to this market have come to be regarded (wrongly) as being synonymous with sustainability. The process becomes one of smug satisfaction, of self-justifying growth and of expansion and spread of tourism. The paper examines what is actually being achieved in practice and suggests that examples of tourism ‘successes’, currently being lauded as role-models of sustainable tourism are at best simply examples of good tourism practice. Despite the industry's protestations to the contrary, these should not automatically be regarded as suitable practices to adopt. It draws the conclusions that the proposed solutions are just a...
TL;DR: It was found that the Verbal-Imagery cognitive style and presentation condition interacted in their effect on overall learning performance (p < .05), and it was observed that Imagers used more diagrams to illustrate their answers than Verbalisers.
Abstract: The effect of text-plus-text versus text-plus-picture computer presentation conditions, and the students' cognitive styles, on learning performance was investigated. In the text-plus-text condition, the learning material content described the working of car braking systems. The text-plus-picture condition consisted of text with additional pictorial information. Fifty-nine 15-16-year-old students in a secondary school were randomly assigned, within sexes, to one of the conditions. Having worked through the computer presented material, they were given a post-test overall learning performance. Immediately following this, they did the Cognitive Styles Analysis (CSA) (Riding, 1991) which measures an individual's position on two cognitive style dimensions; Verbal-Imagery and Wholist-Analytic. It was found that the Verbal-Imagery cognitive style and presentation condition interacted in their effect on overall learning performance (p < .05). In the text-plus-picture condition Imagers were superior to Verbalisers, while the text-plus-text condition Verbalisers did better than Imagers. It was also observed that Imagers used more diagrams to illustrate their answers than Verbalisers. The results are discussed in terms of their implications for instruction.
TL;DR: Copper exposure resembles low pH exposure in freshwater trout, and copper and H+ appear to be similar in both the primary site of their toxic action (the gills) and the secondary physiological consequences which result from acutely lethal exposures.
Abstract: Acutely lethal (24 h) exposure of adult rainbow trout (Oncorhynchus mykiss) to 4.9 μmol copper·l-1 in fresh water (pH 7.9, [Ca2+]≈0.8 mEq·l-1) caused a rapid decline of plasma Na+ and Cl- and arterial O2 tension, and initially a pronounced tachycardia. The internal hypoxia probably resulted from histopathologies observed in the gills of fish exposed to copper, such as cell swelling, thickening and curling of the lamellae, and haematomas. Copper cannot therefore be considered purely as an ionoregulatory toxicant during acutely lethal conditions. Mortality during exposure to copper could not simply be explained by the plasma ionic dilution, nor by the internal hypoxia, since arterial O2 content remained relatively unchanged. Secondary to the ionoregulatory and respiratory disturbances were a number of deleterious physiological responses which included a massive haemoconcentration (haematocrit values as high as 60%) and a doubling of the mean arterial blood pressure. The time-course of these changes suggest that cardiac failure was the final cause of death. In this respect copper exposure resembles low pH exposure in freshwater trout (Milligan and Wood 1982). Copper and H+ appear to be similar in both the primary site of their toxic action (the gills) and the secondary physiological consequences which result from acutely lethal exposures. Furthermore, the acute toxicity syndrome observed may be common to many metals which cause ionoregulatory and/or respiratory problems in freshwater fish.
TL;DR: In this paper, a patient with a category-specific recognition deficit following herpes simplex encephalitis infection was reported to have greater difficulty identifying animals and foodstuffs than inanimate objects.
Abstract: The paper reports a patient with a category-specific recognition deficit following herpes simplex encephalitis infection. The patient, SB, has greater difficulty identifying animals and foodstuffs than inanimate objects. We show that for the impaired categories, SB has intact structural knowledge when accessed visually. However, she was poor at retrieving this knowledge from other input modalities, and she had impaired verbal-semantic knowledge concerning the affected categories. She also showed item-specific consistency across time and modalities. SB's deficit is attributed to a loss of verbal-semantic knowledge. A contrast is drawn between SB and other patients in the literature, and it is suggested that category-specific problems can be linked to a number of different functional impairments. Problems emerge according to the similarity between items at a particular processing level, and to the use of cross-modality associations in differentiating within object classes.