833 research outputs found

    An in vivo evaluation of an lontophoretic Technique for increasing the surface fluoride content in enamel

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    KIMSurface enamel fluoride concentrations were determined in IS subjects before and after topical fluoride applications. These IS subjects were divided into 2 groups, one of which received the fluoride applications iontophoreti- cally whereas the control group had the identical fluoride applications without the use of the current. The results indicate that the greatest increase in fluoride concentrations resulted after 3 applications done at weekly intervals when the iontoplioretic technique was employed. Two iontophoretic fluoride applications with an interval of a week between them resulted in a less marked increase whereas no increase was observed when fluoride was applied once only. The increase in the fluoride concentration of the surface enamel was not as significant when the fluoride was applied without the use of current

    Long-stay medical-surgical intensive care unit patients in South Africa : quality of life and mortality 1 year after discharge

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    BACKGROUND. Although mortality is the primary measure of critical care outcome, the health-related quality of life (HRQOL) of survivors is often diminished. There is a paucity of South African research on HRQOL in intensive care unit (ICU) survivors. OBJECTIVES. To evaluate the 1-year post-discharge data of long-stay ICU patients, a group known to consume 20 - 40% of ICU resources. METHODS. A 1-year prospective observational study was conducted in a multidisciplinary medical-surgical ICU. Adult patients who were mechanically ventilated beyond 6 days were included. Clinical and mortality data were collected. Pre-admission and 6- and 12-month HRQOL were measured with the Short Form-36 questionnaire. Physical and mental component summary scores (PCS and MCS) were calculated. Associations between 12-month mortality and poor HRQOL scores were determined. RESULTS. Of 119 patients enrolled, 40.3% had sustained trauma, 19.3% were post-surgical and 40.3% had medical conditions; 29.2% were HIV-positive (HIV status was known for 74.8% of the cohort). The hospital and 12-month mortality rates were 42.9% and 57.4% (n=66/115), respectively. Age, longer ICU stay, higher disease severity scores and vasopressor use were associated with 12-month mortality. The survivors’ median PCS and MCS at 6 and 12 months were significantly lower compared with pre-admission scores (both p<0.001). At 12 months, 53.1% of survivors demonstrated a poor PCS and 42.9% a poor MCS. Associations with poor 12-month PCS included longer ICU stay, male gender and trauma, while trauma and sepsis were associated with a poor 12-month MCS. Among the 19 trauma survivors, 78.9% had a poor MCS and/or PCS. Of previously employed patients, 54.8% were unemployed at 12 months. CONCLUSIONS. Patients ventilated beyond 6 days in a multidisciplinary ICU had a high mortality. Poor HRQOL at 12 months post discharge was frequently observed among survivors. Trauma was associated with poor 12-month outcomes. These findings highlight the need to further explore the outcomes of long-stay ICU patients in Africa.South African Critical Care Society research grant.http://www.samj.org.zadm2022Critical Car

    Straight Line Orbits in Hamiltonian Flows

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    We investigate periodic straight-line orbits (SLO) in Hamiltonian force fields using both direct and inverse methods. A general theorem is proven for natural Hamiltonians quadratic in the momenta in arbitrary dimension and specialized to two and three dimension. Next we specialize to homogeneous potentials and their superpositions, including the familiar H\'enon-Heiles problem. It is shown that SLO's can exist for arbitrary finite superpositions of NN-forms. The results are applied to a family of generalized H\'enon-Heiles potentials having discrete rotational symmetry. SLO's are also found for superpositions of these potentials.Comment: laTeX with 6 figure

    Identification strategy for unknown pollutants using high-resolution mass spectrometry: Androgen-disrupting compounds identified through effect-directed analysis

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    Effect-directed analysis has been applied to a river sediment sample of concern to identify the compounds responsible for the observed effects in an in vitro (anti-)androgenicity assay. For identification after non-target analysis performed on a high-resolution LTQ-Orbitrap, we developed a de novo identification strategy including physico-chemical parameters derived from the effect-directed analysis approach. With this identification strategy, we were able to handle the immense amount of data produced by non-target accurate mass analysis. The effect-directed analysis approach, together with the identification strategy, led to the successful identification of eight androgen-disrupting compounds belonging to very diverse compound classes: an oxygenated polyaromatic hydrocarbon, organophosphates, musks, and steroids. This is one of the first studies in the field of environmental analysis dealing with the difficult task of handling the large amount of data produced from non-target analysis. The combination of bioassay activity assessment, accurate mass measurement, and the identification and confirmation strategy is a promising approach for future identification of environmental key toxicants that are not included as priority pollutants in monitoring programs

    Multi-Target Prediction: A Unifying View on Problems and Methods

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    Multi-target prediction (MTP) is concerned with the simultaneous prediction of multiple target variables of diverse type. Due to its enormous application potential, it has developed into an active and rapidly expanding research field that combines several subfields of machine learning, including multivariate regression, multi-label classification, multi-task learning, dyadic prediction, zero-shot learning, network inference, and matrix completion. In this paper, we present a unifying view on MTP problems and methods. First, we formally discuss commonalities and differences between existing MTP problems. To this end, we introduce a general framework that covers the above subfields as special cases. As a second contribution, we provide a structured overview of MTP methods. This is accomplished by identifying a number of key properties, which distinguish such methods and determine their suitability for different types of problems. Finally, we also discuss a few challenges for future research

    ENIGMA and global neuroscience: A decade of large-scale studies of the brain in health and disease across more than 40 countries

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    This review summarizes the last decade of work by the ENIGMA (Enhancing NeuroImaging Genetics through Meta Analysis) Consortium, a global alliance of over 1400 scientists across 43 countries, studying the human brain in health and disease. Building on large-scale genetic studies that discovered the first robustly replicated genetic loci associated with brain metrics, ENIGMA has diversified into over 50 working groups (WGs), pooling worldwide data and expertise to answer fundamental questions in neuroscience, psychiatry, neurology, and genetics. Most ENIGMA WGs focus on specific psychiatric and neurological conditions, other WGs study normal variation due to sex and gender differences, or development and aging; still other WGs develop methodological pipelines and tools to facilitate harmonized analyses of "big data" (i.e., genetic and epigenetic data, multimodal MRI, and electroencephalography data). These international efforts have yielded the largest neuroimaging studies to date in schizophrenia, bipolar disorder, major depressive disorder, post-traumatic stress disorder, substance use disorders, obsessive-compulsive disorder, attention-deficit/hyperactivity disorder, autism spectrum disorders, epilepsy, and 22q11.2 deletion syndrome. More recent ENIGMA WGs have formed to study anxiety disorders, suicidal thoughts and behavior, sleep and insomnia, eating disorders, irritability, brain injury, antisocial personality and conduct disorder, and dissociative identity disorder. Here, we summarize the first decade of ENIGMA's activities and ongoing projects, and describe the successes and challenges encountered along the way. We highlight the advantages of collaborative large-scale coordinated data analyses for testing reproducibility and robustness of findings, offering the opportunity to identify brain systems involved in clinical syndromes across diverse samples and associated genetic, environmental, demographic, cognitive, and psychosocial factors

    Contrasting Nephropathic Responses to Oral Administration of Extract of Cultured Penicillium polonicum in Rat and Primate

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    Liquid- or solid substrate-cultured Penicillium polonicum administered in feed to rats over several days evokes a histopathological response in kidney involving apoptosis and abnormal mitosis in proximal tubules. The amphoteric toxin is yet only partly characterized, but can be isolated from cultured sporulating biomass in a fraction that is soluble in water and ethanol, and exchangeable on either anion- or cation-exchange resins. After several weeks of treatment renal proximal tubule distortion became striking on account of karyocytomegaly, but even treatment for nearly two years remained asymptomatic. Extract from a batch of solid substrate fermentation of P. polonicum on shredded wheat was incorporated into feed for rats during four consecutive days, and also given as an aqueous solution by oral gavage to a vervet monkey daily for 10 days. Treatment was asymptomatic for both types of animal. Rat response was evident as the typical renal apoptosis and karyomegaly. In contrast there was no such response in the primate; and neither creatinine clearance nor any haematological characteristic or serum component concentration deviated from a control or from historical data for this primate. The contrast is discussed concerning other negative findings for P. polonicum in pigs and hamsters. Renal karyomegaly, as a common rat response to persistent exposure to ochratoxin A, is not known in humans suspected as being exposed to more than the usual trace amounts of dietary ochratoxin A. Therefore the present findings question assumptions that human response to ochratoxin A conforms to that in the rat

    Matched sizes of activating and inhibitory receptor/ligand pairs are required for optimal signal integration by human Natural Killer cells

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    It has been suggested that receptor-ligand complexes segregate or co-localise within immune synapses according to their size, and this is important for receptor signaling. Here, we set out to test the importance of receptor-ligand complex dimensions for immune surveillance of target cells by human Natural Killer (NK) cells. NK cell activation is regulated by integrating signals from activating receptors, such as NKG2D, and inhibitory receptors, such as KIR2DL1. Elongating the NKG2D ligand MICA reduced its ability to trigger NK cell activation. Conversely, elongation of KIR2DL1 ligand HLA-C reduced its ability to inhibit NK cells. Whereas normal-sized HLA-C was most effective at inhibiting activation by normal-length MICA, only elongated HLA-C could inhibit activation by elongated MICA. Moreover, HLA-C and MICA that were matched in size co-localised, whereas HLA-C and MICA that were different in size were segregated. These results demonstrate that receptor-ligand dimensions are important in NK cell recognition, and suggest that optimal integration of activating and inhibitory receptor signals requires the receptor-ligand complexes to have similar dimensions

    The lived experience of discrimination by white women in committed interracial relationships with black men

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    Abstract: This study explores the experiences of discrimination by white women in committed interracial relationships with black men within the South African context from a descriptive phenomenological perspective. Three white females in committed interracial relationships with black males were recruited and interviewed. Open-ended interviews were conducted in order to elicit rich and in-depth first-person descriptions of the participants’ lived experiences of discrimination as a result of being in committed interracial relationships. The data analysis entailed a descriptive phenomenological content analysis and description. The results of this study suggest that white women in committed interracial relationships with black men experienced discrimination in various contexts where discrimination manifests as either a negative or a positive encounter; in addition, discrimination evokes various emotional responses and is coped with in either maladaptive or adaptive ways. Finally the experience of discrimination, although personal, necessarily impacts on the interracial relationship. Discrimination experienced by white women in committed interracial relationships with black men is thus multi-layered and both an intra-personal and inter-personal phenomenon
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