1,516 research outputs found

    Demographic change and response: social context and the practice of birth control in six countries

    Get PDF
    This paper expands on Kingsley Davis’s demographic thesis of change and re- sponse. Specifically, we consider the social context that accounts for the primacy of particular birth control methods that bring about fertility change during specific time periods. We examine the relevance of state policy (including national family planning programs), the international population establishment, the medical profession, organized religion, and women’s groups using case studies from Japan, Russia, Puerto Rico, China, India, and Cameroon. Some of these countries are undergoing the second demographic transition, others the first. Despite variations in context, heavy reliance on sterilization and/or abortion as a means of birth control is a major response in most of these countries. The key roles of the medical profession and state policy are discussed, along with the general lack of influence of religion and of women’s groups in these countries

    Novel selenium and/or copper substituted hydroxyapatite-gelatin-chitosan-eggshell membrane nanocomposite scaffolds for bone tissue engineering applications

    Get PDF
    Limitations with the majority of bone therapeutic treatments include low availability, ethical constraints and low biological compatibility. Although a number of choice materials have been exploited successfully, there has always been scope for improvement as well as development of the next-generation of materials. Herein, scaffolds - developed from gelatin, chitosan and eggshell membranes - were crosslinked using tannic acid, and further infused with selenium and/or copper substituted hydroxyapatite nanoparticles to generate a novel nanocomposite substrate. FESEM images of the nanocomposite scaffolds revealed the presence of interconnected pores, mostly spread over the whole surface of the scaffold, alongside XRD and FTIR profiling that detailed the formation of hydroxyapatite as a sole phase. Moreover, physical characterisation of the nanocomposite confirmed that the hydroxyapatite particulates and the eggshell membrane fibres were uniformly distributed and contributed to the surface roughness of the scaffold. Biocompatibility and cytotoxicity of the novel constructs were assessed using the mouse-derived osteoblastic cell line, MC3T3-E1, and standard cell culture assays. Metabolic activity assessment (i.e. MTS assay), LDH-release profiles and Live/Dead staining demonstrated good cell adhesion, viability, and proliferation rates. Accordingly, this work summarises the successful development of a novel construct which may be exploited as a clinical/therapeutic treatment for bone repair as well as a possible translational application as a novel biomaterial for the drug development pipeline

    Sparse Exploratory Factor Analysis

    Get PDF
    Sparse principal component analysis is a very active research area in the last decade. It produces component loadings with many zero entries which facilitates their interpretation and helps avoid redundant variables. The classic factor analysis is another popular dimension reduction technique which shares similar interpretation problems and could greatly benefit from sparse solutions. Unfortunately, there are very few works considering sparse versions of the classic factor analysis. Our goal is to contribute further in this direction. We revisit the most popular procedures for exploratory factor analysis, maximum likelihood and least squares. Sparse factor loadings are obtained for them by, first, adopting a special reparameterization and, second, by introducing additional [Formula: see text]-norm penalties into the standard factor analysis problems. As a result, we propose sparse versions of the major factor analysis procedures. We illustrate the developed algorithms on well-known psychometric problems. Our sparse solutions are critically compared to ones obtained by other existing methods

    An improved non-invasive method for measuring heartbeat of intertidal animals

    Get PDF
    Since its emergence two decades ago, the use of infrared technology for noninvasively measuring the heartbeat rates of invertebrates has provided valuable insight into the physiology and ecology of intertidal organisms. During that time period, the hardware needed for this method has been adapted to currently available electronic components, making the original published description obsolete. This article reviews the history of heartbeat sensing technology, and describes the design and function of a modern and simplified infrared heartbeat rate sensing system compatible with many intertidal and marine invertebrates. This technique overcomes drawbacks and obstacles encountered with previous methods of heartbeat rate measurement, and due to the sensor’s small size, versatility, and noninvasive nature, it creates new possibilities for studies across a wide range of organismal type

    Is spinopelvic sagittal alignment correlated with pain level, functional disability and frontal plane projection angle in women with patellofemoral pain syndrome? A cross-sectional study

    Get PDF
    There is a growing interest concerning the understanding of measurements of spinal and leg alignment in patients with patellofemoral pain syndrome (PFPS). However, evaluating spinopelvic alignment in the sagittal plane with pain level, functional disability and frontal plane projection angle (FPPA) in PFPS has not been adequately addressed. The aim of the study was to identify the correlation of spinopelvic parameters with pain level, functional disability and frontal plane projection angle in women with PFPS. This was a cross–sectional study involving sixty female patients diagnosed with PEPS, with a mean age of 32±6.47. The measurements used in the study included: radiographic parameters (X-Ray), the numeric pain rating scale (NPRS), the Arabic anterior knee pain scale (AAKP/Kujala) and the 2D-FPPA. Spearman correlation analysis was conducted to evaluate the relationship between these parameters. The results of our study demonstrated a strong positive correlation of lumbar lordosis (LL) with pain level and FPPA (r=0.825, r=0.812, p=0.0001). Also, a strong positive correlation of sacral slope (SS) with pain level (r = 0.0.820) and FPPA (r= 0.783). Pelvic tilt (PT) showed a moderate correlation with pain level (r = 0.0.614) and FPPA (r= 0.605), while a weak negative correlation was found between LL, SS and PT and functional disability score (r=-0.397, r=-0.385 and, r=-0.215 p=0.002). It was concluded that LL, SS and PT were significantly related to the pain level, functional disability and frontal plane projection angle in women with PFPS. These spinal alignments should be considered in clinical evaluation of knee-related disorders associated with PFPS

    Is there an association between postural balance and pulmonary function in adults with asthma?

    Get PDF
    OBJECTIVE: Asthma may cause systemic repercussions due to its severity and the effects of treatment. Our objective was to compare posture, balance, functional capacity, and quality of life (QOL) according to the severity of disease, as assessed by pulmonary function levels. METHOD: This cross-sectional study evaluated fifty individuals with asthma. We compared two groups of adult individuals who were divided according to the median of the forced expiratory volume in one second (FEV1) as follows: group A  =  FEV1>;74% predicted; group B  =  FEV

    VCAM-1/α4β1 Integrin Interaction is Crucial for Prompt Recruitment of Immune T Cells into the Brain During the Early Stage of Reactivation of Chronic Infection with \u3cem\u3eToxoplasma gondii\u3c/em\u3e to Prevent Toxoplasmic Encephalitis

    Get PDF
    Reactivation of chronic infection with Toxoplasma gondii can cause life-threatening toxoplasmic encephalitis in immunocompromised individuals. We examined the role of VCAM-1/α4β1 integrin interaction in T cell recruitment to prevent reactivation of the infection in the brain. SCID mice were infected and treated with sulfadiazine to establish a chronic infection. VCAM-1 and ICAM-1 were the endothelial adhesion molecules detected on cerebral vessels of the infected SCID and wild-type animals. Immune T cells from infected wild-type mice were treated with anti-α4 integrin or control antibodies and transferred into infected SCID or nude mice, and the animals received the same antibody every other day. Three days later, sulfadiazine was discontinued to initiate reactivation of infection. Expression of mRNAs for CD3δ, CD4, CD8β, gamma interferon (IFN-γ), and inducible nitric oxide synthase (NOS2) (an effector molecule to inhibit T. gondii growth) and the numbers of CD4+ and CD8+ T cells in the brain were significantly less in mice treated with anti-α4 integrin antibody than in those treated with control antibody at 3 days after sulfadiazine discontinuation. At 6 days after sulfadiazine discontinuation, cerebral tachyzoite-specific SAG1 mRNA levels and numbers of inflammatory foci associated with tachyzoites were markedly greater in anti-α4 integrin antibody-treated than in control antibody-treated animals, even though IFN-γ and NOS2 mRNA levels were higher in the former than in the latter. These results indicate that VCAM-1/α4β1 integrin interaction is crucial for prompt recruitment of immune T cells and induction of IFN-γ-mediated protective immune responses during the early stage of reactivation of chronic T. gondii infection to control tachyzoite growth

    Natalizumab affects T-cell phenotype in multiple sclerosis: implications for JCV reactivation

    Get PDF
    The anti-CD49d monoclonal antibody natalizumab is currently an effective therapy against the relapsing-remitting form of multiple sclerosis (RRMS). Natalizumab therapeutic efficacy is limited by the reactivation of the John Cunningham polyomavirus (JCV) and development of progressive multifocal leukoencephalopathy (PML). To correlate natalizumab-induced phenotypic modifications of peripheral blood T-lymphocytes with JCV reactivation, JCV-specific antibodies (serum), JCV-DNA (blood and urine), CD49d expression and relative abundance of peripheral blood T-lymphocyte subsets were longitudinally assessed in 26 natalizumab-treated RRMS patients. Statistical analyses were performed using GraphPad Prism and R. Natalizumab treatment reduced CD49d expression on memory and effector subsets of peripheral blood T-lymphocytes. Moreover, accumulation of peripheral blood CD8+ memory and effector cells was observed after 12 and 24 months of treatment. CD4+ and CD8+ T-lymphocyte immune-activation was increased after 24 months of treatment. Higher percentages of CD8+ effectors were observed in subjects with detectable JCV-DNA. Natalizumab reduces CD49d expression on CD8+ T-lymphocyte memory and effector subsets, limiting their migration to the central nervous system and determining their accumulation in peripheral blood. Impairment of central nervous system immune surveillance and reactivation of latent JCV, can explain the increased risk of PML development in natalizumab-treated RRMS subjects

    Microglial Sirtuin 2 shapes long-term potentiation in hippocampal slices

    Get PDF
    Copyright © 2020 Sa de Almeida, Vargas, Fonseca-Gomes, Tanqueiro, Belo, Miranda-Lourenço, Sebastião, Diógenes and Pais. This is an open-access article distributed under the terms of the Creative Commons Attribution License (CC BY). The use, distribution or reproduction in other forums is permitted, provided the original author(s) and the copyright owner(s) are credited and that the original publication in this journal is cited, in accordance with accepted academic practice. No use, distribution or reproduction is permitted which does not comply with these terms.Microglial cells have emerged as crucial players in synaptic plasticity during development and adulthood, and also in neurodegenerative and neuroinflammatory conditions. Here we found that decreased levels of Sirtuin 2 (Sirt2) deacetylase in microglia affects hippocampal synaptic plasticity under inflammatory conditions. The results show that long-term potentiation (LTP) magnitude recorded from hippocampal slices of wild type mice does not differ between those exposed to lipopolysaccharide (LPS), a pro-inflammatory stimulus, or BSA. However, LTP recorded from hippocampal slices of microglial-specific Sirt2 deficient (Sirt2-) mice was significantly impaired by LPS. Importantly, LTP values were restored by memantine, an antagonist of N-methyl-D-aspartate (NMDA) receptors. These results indicate that microglial Sirt2 prevents NMDA-mediated excitotoxicity in hippocampal slices in response to an inflammatory signal such as LPS. Overall, our data suggest a key-protective role for microglial Sirt2 in mnesic deficits associated with neuroinflammation.This study was supported by Santa Casa da Misericórdia de Lisboa (MB37-2017), GAPIC Research Program of the University of Lisbon Medical School (n° 2014002 and n° 2015028) and the following doctoral grants: PD/BD/128091/2016, SFRH/BD/118238/2016, PD/BD/114337/2016, and PD/BD/1144- 41/2016.info:eu-repo/semantics/publishedVersio

    Chiral Polymerization in Open Systems From Chiral-Selective Reaction Rates

    Full text link
    We investigate the possibility that prebiotic homochirality can be achieved exclusively through chiral-selective reaction rate parameters without any other explicit mechanism for chiral bias. Specifically, we examine an open network of polymerization reactions, where the reaction rates can have chiral-selective values. The reactions are neither autocatalytic nor do they contain explicit enantiomeric cross-inhibition terms. We are thus investigating how rare a set of chiral-selective reaction rates needs to be in order to generate a reasonable amount of chiral bias. We quantify our results adopting a statistical approach: varying both the mean value and the rms dispersion of the relevant reaction rates, we show that moderate to high levels of chiral excess can be achieved with fairly small chiral bias, below 10%. Considering the various unknowns related to prebiotic chemical networks in early Earth and the dependence of reaction rates to environmental properties such as temperature and pressure variations, we argue that homochirality could have been achieved from moderate amounts of chiral selectivity in the reaction rates.Comment: 15 pages, 6 figures, accepted for publication in Origins of Life and Evolution of Biosphere
    corecore