1,052 research outputs found

    B Cells Activated in Lymph Nodes in Response to Ultraviolet Irradiation or by Interleukin-10 Inhibit Dendritic Cell Induction of Immunity

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    Ultraviolet (UV) radiation suppresses systemic immunity. We explored these cellular mechanisms by exposing mice to systemically immunosuppressive doses of UV radiation and then analyzing cell phenotype and function in the lymphoid organs. Although UV radiation increased total cell number in the draining lymph nodes (DLN), it did not alter the activation state of dendritic cells (DC). Rather, UV radiation selectively activated lymph node B cells, with these cells being larger and expressing higher levels of both anti-major histocompatibility complex II and B220 but not co-stimulatory molecules. This phenotype resembled that of a B cell geared toward immune tolerance. To test whether UV radiation-activated B cells were responsible for immunosuppression, DC and B cells were conjugated to antigen ex vivo and transferred into naïve hosts. Although DC by themselves activated T cells, when the B cells from UV radiation-irradiated mice were co-injected with DC, they suppressed DC activation of immunity. Interleukin (IL)-10-activated B cells also suppressed DC induction of immunity, suggesting that IL-10 may be involved in this suppressive effect of UV radiation. These results demonstrate a new mechanism of UV radiation immunosuppression whereby UV radiation activates B cells in the skin-DLN that can suppress DC activation of T cell-mediated immunity

    Research to Practice: Trends and Emerging Issues Regarding SSA/VR Reimbursements for SSI/SSDI Recipients

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    This brief discusses the declining amount of reimbursement paid to public VR agencies from federal fiscal year (FFY) 2002 to FFY 2005 by considering the impact that fewer claims submitted and a rising SGA level may have on the amount of reimbursement paid

    United States Immigration: What’s Wrong and How to Fix It

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    The main objective of this thesis is to identify the most beneficial ways to reform the current immigration system of the United States of America. To do so, this paper first identifies and explains how the current immigration system works. The thesis then analyzes how the current system is broken, and how this broken system has lead to the undocumented immigrant population. It explains that how the system is structured, incentivizes immigrants to enter unauthorized. Next it identifies the benefits and costs of the undocumented immigrant population to the United States. This is done to better understand what should be done with this population. Finally it shows the four most beneficial ways to fix the current immigration system

    Diurnal Urinary Excretion of DHP in Steers Fed \u3cem\u3eLeucaena leucocephala\u3c/em\u3e

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    Leucaena (Leucaena leucocephala) contains the toxin mimosine which is quickly degraded by rumen microorganisms to isomers of dihydroxypyridine (DHP). DHP is detrimental to animal production, causing reduced thyroid hormones, reduced weight gain, goiter and severe deficiencies in essential minerals (Tsai and Ling 1971; Hammond 1995). There are several methods of testing for exposure to DHP toxicity but the simplest is the colorimetric urine spot test (Graham et al. 2013). Several researchers have noted high variability in the excretion of DHP among animals on similar leucaena diets (Dalzell et al. 2012; Phaikaew et al. 2012) and even in the same animal over sequential samplings (O\u27Reagain and Shelton 2013). They noted that it was possible to obtain samples with very low DHP in unprotected animals on high leucaena diets, leading to the false conclusion that the animal was successfully degrading DHP in the rumen. This study examined the extent and possible causes of variation of DHP concentration in spot urine samples taken over a 6-week period, including an intensive sampling over a 24 hour period

    The Efficacy of \u3cem\u3ein vitro Synergistes jonesii\u3c/em\u3e Inoculum in Preventing DHP Toxicity in Steers Fed Leucaena-Grass Diets

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    Leucaena leucocephala (leucaena) is a valuable forage tree legume for tropical animal production that contains the toxin mimosine. The breakdown products of mimosine in ruminants (3,4-DHP and 2,3-DHP) can adversely affect their health and limit weight gains (Jones and Hegarty 1984). The rumen bacterium Synergistes jonesii, introduced into Australia in 1983 was shown to completely and rapidly degrade these toxins to safe levels (Jones and Megarrity 1986). Since 1996, an in vitro produced inoculum has been made commercially available to Australian graziers (Klieve et al. 2002). Accordingly, the issue of leucaena toxicity in Australia was thought to be resolved. However, extensive testing in 2004 found that up to 50% of Queensland cattle herds consuming leucaena were excreting high levels of urinary DHP suggesting sub-clinical toxicity remained an issue for graziers (Dalzell et al. 2012). Some of these herds had previously been inoculated with in vitro S. jonesii suggesting the inoculum may not be able to either persist within a herd, or remain effective in degrading DHP. The aim of this study was to assess the capability of the in vitro S. jonesii inoculum to efficiently break down DHP in a controlled feeding trial environment

    Implementing Diagnostic Imaging Services in a Rural Setting of Extreme Poverty: Five Years of X-ray and Ultrasound Service Delivery in Achham, Nepal

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    Introduction: Diagnostic radiology services are severely lacking in many rural settings and the implementation of these services poses complex challenges. The purpose of this paper is to describe the implementation of diagnostic radiology services at a district-level hospital in Achham, a rural district in Nepal. Methods and Materials: We conducted a retrospective review of the implementation of diagnostic radiology services. We compiled a list of implementation challenges and proposed solutions based on an internal review of historical data, hospital records, and the experiences of hospital staff members. We used a seven-domain analytic framework to structure our discussion of these challenges. Results: We documented the first five years of challenges faced and lessons learned by the non-profit organization Possible while implementing and providing diagnostic radiology services for the first time in a remote location. Additionally, we documented the uptake of these services through the first five years of operations. During this time, the number of X-rays performed increased 271%, while ultrasounds increased 258%. The main challenges included educating the community about the appropriate use of these services, recruiting trained providers, and coordinating referral care and consultations for higher-level diagnostics and treatment. Finally, investments in training providers and technicians, as well as investments in infrastructure, primarily the installation of solar panels to maintain a power supply, were critical to sustaining services. Discussion: This experience demonstrates that reliable and sustained services can be deployed even in extremely remote areas and identifies challenges that other implementers may face in similar program implementation

    Pharmacologically antagonizing the CXCR4-CXCL12 chemokine pathway with AMD3100 inhibits sunlight-induced skin cancer

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    One way sunlight causes skin cancer is by suppressing anti-tumor immunity. A major mechanism involves altering mast cell migration via the C-X-C motif chemokine receptor 4–C-X-C motif chemokine ligand 12 (CXCR4-CXCL12) chemokine pathway. We have discovered that pharmacologically blocking this pathway with the CXCR4 antagonist AMD3100 prevents both UV radiation-induced immune suppression and skin cancer. The majority of control mice receiving UV-only developed histopathologically confirmed squamous cell carcinomas. In contrast, skin tumor incidence and burden was significantly lower in AMD3100-treated mice. Perhaps most striking was that AMD3100 completely prevented the outgrowth of latent tumors that occurred once UV irradiation ceased. AMD3100 protection from UV immunosuppression and skin cancer was associated with reduced mast cell infiltration into the skin, draining lymph nodes, and the tumor itself. Thus a major target of CXCR4 antagonism was the mast cell. Our results indicate that interfering with UV-induced CXCL12 by antagonizing CXCR4 significantly inhibits skin tumor development by blocking UV-induced effects on mast cells. Hence, the CXCR4-CXCL12 chemokine pathway is a novel therapeutic target in the prevention of UV-induced skin cancer

    Increased ductility of Ti-6Al-4V by interlayer milling during directed energy deposition

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    Additive manufacturing (AM) often results in high strength but poor ductility in titanium alloys. Hybrid AM is a solution capable of improving both ductility and strength. In this study, hybrid AM of Ti-6Al-4V was achieved by coupling directed energy deposition with interlayer machining. The microstructure, residual stress, and microhardness were examined to explain how interlayer machining caused a 63% improvement in ductility while retaining an equivalent strength to as-printed samples. Interlayer machining introduced recurrent interruptions in printing that allowed for slow cooling-induced coarsening of acicular α laths at the machined interfaces. The coarse α laths on the selectively machined layers increased dislocation motion under tensile loads and improved bulk ductility. The results highlighted in this publication demonstrate the feasibility of hybrid AM to enhance the toughness of titanium alloys
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