3,530 research outputs found

    Historic landmarks in clinical transplantation: Conclusions from the consensus conference at the University of California, Los Angeles

    Get PDF
    The transplantation of organs, cells, and tissues has burgeoned during the last quarter century, with the development of multiple new specialty fields. However, the basic principles that made this possible were established over a three-decade period, beginning during World War II and ending in 1974. At the historical consensus conference held at UCLA in March 1999, 11 early workers in the basic science or clinical practice of transplantation (or both) reached agreement on the most significant contribution of this era that ultimately made transplantation the robust clinical discipline it is today. These discoveries and achievements are summarized here is six tables and annotated with references

    Open Science and Open Innovation in Socio-Political Context: Knowledge Production and Societal Impact in an Age of Populism

    Get PDF
    This conceptual paper traces the origins and progress of Open Science and proposes its generative coupling to Open Innovation in the contemporary socio-political context; where universities are re-imaging their civic missions in the face of anti-establishment populist politics. This setting is one of changing knowledge production regimes and institutional pressures that create contradictions identifiable through the prism of the series of scientific norms conceptualised by Robert K. Merton. This paper privileges a sociological perspective to proffer scientific knowledge production as a societally embedded process, which is well illustrated by scholarship in the Science and Technology Studies (STS) and Science in Society fields. In doing so, it identifies the co-evolution, co-existence and co-production of Open Science with Open Innovation; and notes how it shares the attributes of other recent diagnoses of changing knowledge production regimes; in particular Mode 2, post-normal science and the Quadruple Helix. It also argues that Open Science can be coupled with Open Innovation to catalyse positive societal change, but that the rise of a populist post-truth era opposed to objectivity, expertise and technocratic political solutions gives the demand for openness and participation a different complexion. Merton’s norms provide a useful lens to observe recent shifts in the delivery of science, knowledge and innovation in society towards more inclusive, ethical and sustainable outcomes; and expose the limited reflection on how the appropriation and exploitation of open scientific knowledge encounters industrial R&D and Open Innovation

    A pentapeptide as minimal antigenic determinant for MHC class I-restricted T lymphocytes

    Get PDF
    Peptides that are antigenic for T lymphocytes are ligands for two receptors, the class I or II glycoproteins that are encoded by genes in the major histocompatibility complex, and the idiotypic / chain T-cell antigen receptor1–9. That a peptide must bind to an MHC molecule to interact with a T-cell antigen receptor is the molecular basis of the MHC restriction of antigen-recognition by T lymphocytes10,11. In such a trimolecular interaction the amino-acid sequence of the peptide must specify the contact with both receptors: agretope residues bind to the MHC receptor and epitope residues bind to the T-cell antigen receptor12,13. From a compilation of known antigenic peptides, two algorithms have been proposed to predict antigenic sites in proteins. One algorithm uses linear motifs in the sequence14, whereas the other considers peptide conformation and predicts antigenicity for amphipathic -helices15,16. We report here that a systematic delimitation of an antigenic site precisely identifies a predicted pentapeptide motif as the minimal antigenic determinant presented by a class I MHC molecule and recognized by a cytolytic T lymphocyte clone

    MTN-001: Randomized Pharmacokinetic Cross-Over Study Comparing Tenofovir Vaginal Gel and Oral Tablets in Vaginal Tissue and Other Compartments

    Get PDF
    Background: Oral and vaginal preparations of tenofovir as pre-exposure prophylaxis (PrEP) for human immunodeficiency virus (HIV) infection have demonstrated variable efficacy in men and women prompting assessment of variation in drug concentration as an explanation. Knowledge of tenofovir concentration and its active form, tenofovir diphosphate, at the putative vaginal and rectal site of action and its relationship to concentrations at multiple other anatomic locations may provide key information for both interpreting PrEP study outcomes and planning future PrEP drug development. Objective: MTN-001 was designed to directly compare oral to vaginal steady-state tenofovir pharmacokinetics in blood, vaginal tissue, and vaginal and rectal fluid in a paired cross-over design. Methods and Findings: We enrolled 144 HIV-uninfected women at 4 US and 3 African clinical research sites in an open label, 3-period crossover study of three different daily tenofovir regimens, each for 6 weeks (oral 300 mg tenofovir disoproxil fumarate, vaginal 1% tenofovir gel [40 mg], or both). Serum concentrations after vaginal dosing were 56-fold lower than after oral dosing (p<0.001). Vaginal tissue tenofovir diphosphate was quantifiable in ≥90% of women with vaginal dosing and only 19% of women with oral dosing. Vaginal tissue tenofovir diphosphate was ≥130-fold higher with vaginal compared to oral dosing (p<0.001). Rectal fluid tenofovir concentrations in vaginal dosing periods were higher than concentrations measured in the oral only dosing period (p<0.03). Conclusions: Compared to oral dosing, vaginal dosing achieved much lower serum concentrations and much higher vaginal tissue concentrations. Even allowing for 100-fold concentration differences due to poor adherence or less frequent prescribed dosing, vaginal dosing of tenofovir should provide higher active site concentrations and theoretically greater PrEP efficacy than oral dosing; randomized topical dosing PrEP trials to the contrary indicates that factors beyond tenofovir's antiviral effect substantially influence PrEP efficacy. Trial Registration: ClinicalTrials.gov NCT00592124

    Recognizing Speech in a Novel Accent: The Motor Theory of Speech Perception Reframed

    Get PDF
    The motor theory of speech perception holds that we perceive the speech of another in terms of a motor representation of that speech. However, when we have learned to recognize a foreign accent, it seems plausible that recognition of a word rarely involves reconstruction of the speech gestures of the speaker rather than the listener. To better assess the motor theory and this observation, we proceed in three stages. Part 1 places the motor theory of speech perception in a larger framework based on our earlier models of the adaptive formation of mirror neurons for grasping, and for viewing extensions of that mirror system as part of a larger system for neuro-linguistic processing, augmented by the present consideration of recognizing speech in a novel accent. Part 2 then offers a novel computational model of how a listener comes to understand the speech of someone speaking the listener's native language with a foreign accent. The core tenet of the model is that the listener uses hypotheses about the word the speaker is currently uttering to update probabilities linking the sound produced by the speaker to phonemes in the native language repertoire of the listener. This, on average, improves the recognition of later words. This model is neutral regarding the nature of the representations it uses (motor vs. auditory). It serve as a reference point for the discussion in Part 3, which proposes a dual-stream neuro-linguistic architecture to revisits claims for and against the motor theory of speech perception and the relevance of mirror neurons, and extracts some implications for the reframing of the motor theory

    The role of clathrin in post-golgi trafficking in toxoplasma gondii

    Get PDF
    Apicomplexan parasites are single eukaryotic cells with a highly polarised secretory system that contains unique secretory organelles (micronemes and rhoptries) that are required for host cell invasion. In contrast, the role of the endosomal system is poorly understood in these parasites. With many typical endocytic factors missing, we speculated that endocytosis depends exclusively on a clathrin-mediated mechanism. Intriguingly, in Toxoplasma gondii we were only able to observe the endogenous clathrin heavy chain 1 (CHC1) at the Golgi, but not at the parasite surface. For the functional characterisation of Toxoplasma gondii CHC1 we generated parasite mutants conditionally expressing the dominant negative clathrin Hub fragment and demonstrate that CHC1 is essential for vesicle formation at the trans-Golgi network. Consequently, the functional ablation of CHC1 results in Golgi aberrations, a block in the biogenesis of the unique secretory microneme and rhoptry organelles, and of the pellicle. However, we found no morphological evidence for clathrin mediating endocytosis in these parasites and speculate that they remodelled their vesicular trafficking system to adapt to an intracellular lifestyle

    Adiponectin, free fatty acids, and cardiovascular outcomes in patients with type 2 diabetes and acute coronary syndrome

    Get PDF
    OBJECTIVE: In observational cohorts, adiponectin is inversely associated and free fatty acids (FFAs) are directly associated with incident coronary heart disease (CHD). Adiponectin tends to be reduced and FFAs elevated in type 2 diabetes. We investigated relationships of adiponectin and FFA and major adverse cardiovascular events (MACEs) and death in patients with acute coronary syndrome (ACS) and type 2 diabetes using data from the AleCardio trial, which compared the PPAR-α/γ agonist aleglitazar with placebo. RESEARCH DESIGN AND METHODS: Using Cox regression adjusted for demographic, laboratory, and treatment variables, we determined associations of baseline adiponectin and FFAs, or the change in adiponectin and FFAs from baseline, with MACEs (cardiovascular death, myocardial infarction, or stroke) and death. RESULTS: A twofold higher baseline adiponectin (n = 6,998) was directly associated with risk of MACEs (hazard ratio [HR] 1.17 [95% CI 1.08-1.27]) and death (HR 1.53 [95% CI 1.35-1.73]). A doubling of adiponectin from baseline to month 3 (n = 6,325) was also associated with risk of death (HR 1.20 [95% CI 1.03-1.41]). Baseline FFAs (n = 7,038), but not change in FFAs from baseline (n = 6,365), were directly associated with greater risk of MACEs and death. There were no interactions with study treatment. CONCLUSIONS: In contrast to prior observational data for incident CHD, adiponectin is prospectively associated with MACEs and death in patients with type 2 diabetes and ACS, and an increase in adiponectin from baseline is directly related to death. These findings raise the possibility that adiponectin has different effects in patients with type 2 diabetes and ACS than in populations without prevalent cardiovascular disease. Consistent with prior data, FFAs are directly associated with adverse outcomes
    corecore