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Barack Obama's America : how new conceptions of race, family, and religion ended the Reagan era
\"The election of Barack Obama to the presidency marks a conclusive end to the Reagan era, writes John Kenneth White in Barack Obama's America. Reagan symbolized a 1950s and 1960s America, largely white and suburban, with married couples and kids at home, who attended church more often than not. Obama's election marks a new era, the author writes. Whites will be a minority by 2042. Marriage is at an all-time low. Cohabitation has increased from a half-million couples in 1960 to more than 5 million in 2000 to even more this year. Gay marriages and civil unions are redefining what it means to be a family. And organized religions are suffering, even as Americans continue to think of themselves as a religious people. Obama's inauguration was a defining moment in the political destiny of this country, based largely on demographic shifts, as described in Barack Obama's America.\" -- Publisher's description.
Book
Vitamin D, infections and immunity
Vitamin D, best known for its role in skeletal health, has emerged as a key regulator of innate immune responses to microbial threat. In immune cells such as macrophages, expression of CYP27B1, the 25-hydroxyvitamin D 1α-hydroxylase, is induced by immune-specific inputs, leading to local production of hormonal 1,25-dihydroxyvitamin D (1,25D) at sites of infection, which in turn directly induces the expression of genes encoding antimicrobial peptides. Vitamin D signaling is active upstream and downstream of pattern recognition receptors, which promote front-line innate immune responses. Moreover, 1,25D stimulates autophagy, which has emerged as a mechanism critical for control of intracellular pathogens such as M. tuberculosis. Strong laboratory and epidemiological evidence links vitamin D deficiency to increased rates of conditions such as dental caries, as well as inflammatory bowel diseases arising from dysregulation of innate immune handling intestinal flora. 1,25D is also active in signaling cascades that promote antiviral innate immunity; 1,25D-induced expression of the antimicrobial peptide CAMP/LL37, originally characterized for its antibacterial properties, is a key component of antiviral responses. Poor vitamin D status is associated with greater susceptibility to viral infections, including those of the respiratory tract. Although the severity of the COVID-19 pandemic has been alleviated in some areas by the arrival of vaccines, it remains important to identify therapeutic interventions that reduce disease severity and mortality, and accelerate recovery. This review outlines of our current knowledge of the mechanisms of action of vitamin D signaling in the innate immune system. It also provides an assessment of the therapeutic potential of vitamin D supplementation in infectious diseases, including an up-to-date analysis of the putative benefits of vitamin D supplementation in the ongoing COVID-19 crisis.
Journal Article
Emerging Roles of Vitamin D-Induced Antimicrobial Peptides in Antiviral Innate Immunity
Vitamin D deficiency, characterized by low circulating levels of calcifediol (25-hydroxyvitamin D, 25D) has been linked to increased risk of infections of bacterial and viral origin. Innate immune cells produce hormonal calcitriol (1,25-dihydroxyvitamin D, 1,25D) locally from circulating calcifediol in response to pathogen threat and an immune-specific cytokine network. Calcitriol regulates gene expression through its binding to the vitamin D receptor (VDR), a ligand-regulated transcription factor. The hormone-bound VDR induces the transcription of genes integral to innate immunity including pattern recognition receptors, cytokines, and most importantly antimicrobial peptides (AMPs). Transcription of the human AMP genes β-defensin 2/defensin-β4 (HBD2/DEFB4) and cathelicidin antimicrobial peptide (CAMP) is stimulated by the VDR bound to promoter-proximal vitamin D response elements. HDB2/DEFB4 and the active form of CAMP, the peptide LL-37, which form amphipathic secondary structures, were initially characterized for their antibacterial actively. Notably, calcitriol signaling induces secretion of antibacterial activity in vitro and in vivo, and low circulating levels of calcifediol are associated with diverse indications characterized by impaired antibacterial immunity such as dental caries and urinary tract infections. However, recent work has also provided evidence that the same AMPs are components of 1,25D-induced antiviral responses, including those against the etiological agent of the COVID-19 pandemic, the SARS-CoV2 coronavirus. This review surveys the evidence for 1,25D-induced antimicrobial activity in vitro and in vivo in humans and presents our current understanding of the potential mechanisms by which CAMP and HBD2/DEFB4 contribute to antiviral immunity.
Journal Article
Skeletal and Extraskeletal Actions of Vitamin D: Current Evidence and Outstanding Questions
Abstract
The etiology of endemic rickets was discovered a century ago. Vitamin D is the precursor of 25-hydroxyvitamin D and other metabolites, including 1,25(OH)2D, the ligand for the vitamin D receptor (VDR). The effects of the vitamin D endocrine system on bone and its growth plate are primarily indirect and mediated by its effect on intestinal calcium transport and serum calcium and phosphate homeostasis. Rickets and osteomalacia can be prevented by daily supplements of 400 IU of vitamin D. Vitamin D deficiency (serum 25-hydroxyvitamin D <50 nmol/L) accelerates bone turnover, bone loss, and osteoporotic fractures. These risks can be reduced by 800 IU of vitamin D together with an appropriate calcium intake, given to institutionalized or vitamin D–deficient elderly subjects. VDR and vitamin D metabolic enzymes are widely expressed. Numerous genetic, molecular, cellular, and animal studies strongly suggest that vitamin D signaling has many extraskeletal effects. These include regulation of cell proliferation, immune and muscle function, skin differentiation, and reproduction, as well as vascular and metabolic properties. From observational studies in human subjects, poor vitamin D status is associated with nearly all diseases predicted by these extraskeletal actions. Results of randomized controlled trials and Mendelian randomization studies are supportive of vitamin D supplementation in reducing the incidence of some diseases, but, globally, conclusions are mixed. These findings point to a need for continued ongoing and future basic and clinical studies to better define whether vitamin D status can be optimized to improve many aspects of human health. Vitamin D deficiency enhances the risk of osteoporotic fractures and is associated with many diseases. We review what is established and what is plausible regarding the health effects of vitamin D.
Journal Article
Vitamin D and Immunity in Infants and Children
The last couple of decades have seen an explosion in our interest and understanding of the role of vitamin D in the regulation of immunity. At the molecular level, the hormonal form of vitamin D signals through the nuclear vitamin D receptor (VDR), a ligand-regulated transcription factor. The VDR and vitamin D metabolic enzymes are expressed throughout the innate and adaptive arms of the immune system. The advent of genome-wide approaches to gene expression profiling have led to the identification of numerous VDR-regulated genes implicated in the regulation of innate and adaptive immunity. The molecular data infer that vitamin D signaling should boost innate immunity against pathogens of bacterial or viral origin. Vitamin D signaling also suppresses inflammatory immune responses that underlie autoimmunity and regulate allergic responses. These findings have been bolstered by clinical studies linking vitamin D deficiency to increased rates of infections, autoimmunity, and allergies. Our goals here are to provide an overview of the molecular basis for immune system regulation and to survey the clinical data from pediatric populations, using randomized placebo-controlled trials and meta-analyses where possible, linking vitamin D deficiency to increased rates of infections, autoimmune conditions, and allergies, and addressing the impact of supplementation on these conditions.
Journal Article
Illustrated trees of Britain & Europe
Trees are of enduring interest to naturalists and gardeners alike. This book covers all European species, as well as many introduced species from all over the world.
Book
Vitamin D metabolism and signaling in the immune system
Vitamin D has emerged as a pleiotropic regulator of human physiology, and recent work has revealed that it has several roles in control of human immune system function. Vitamin D was originally characterized for its role in calcium homeostasis, and the active form, 1,25-dihydroxyvitamin D (1,25D), can be produced in the kidney by 1α-hydroxylation of circulating 25-hydroxyvitamin D catalyzed by the enzyme CYP27B1. Renal CYP27B1 expression is regulated by calcium regulatory inputs, and 1,25D produced in the kidney was thought to function largely as an endocrine hormone. However, it is now clear that CYP27B1 is expressed in numerous tissues, and that 1,25D acts at several sites in the body in an intracrine or paracrine manner. In particular, both CYP27B1 and the vitamin D receptor (VDR) are expressed in several cell types in the immune system, where CYP27B1 production is controlled by a number of immune-specific inputs. Recent research has opened several windows on the molecular mechanisms by which 1,25D signaling regulates both innate and adaptive immune responses in humans. Moreover, intervention trials are beginning to provide evidence that vitamin D supplementation can bolster clinical responses to infection. This review will discuss recent developments in our understanding of how immune signaling controls local vitamin D metabolism and how, in turn, the 1,25D-bound VDR modulates immune system function. A particular emphasis will be placed on the interplay between vitamin D signaling and signaling through different classes of pattern recognition receptors in the production of antimicrobial peptides during innate immune responses to microbial infection.
Journal Article