66 resultados para GRAFT POLYMERS
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INTRODUCTION: Gastrointestinal graft-versus-host disease (GI-GvHD) is extremely debilitating and is multifactorial in its causative factors, management and treatment. It is an exaggeration of normal physiological mechanisms wherein the donor immune system attempts to rid itself of the host. The inflammatory process that follows has the benefit of providing an anti-tumour effect for many diseases, but unfortunately in patients undergoing human stem-cell transplantation, the nature of the inflammation can result in disability, wasting and death. AIM: The aim of this article is to discuss the pathophysiology of this often misunderstood or misdiagnosed condition, as well as its signs and symptoms, management and considerations for nursing care. Considerations for nursing practice: While the medical management is aimed at minimising GvHD through the reduction of T-cell production and proliferation and gastrointestinal decolonisation, the nursing care is often focused on the signs and symptoms that can have the most prominent impact on patients. CONCLUSION: GI-GvHD has serious life-threatening complications, namely wasting syndrome, diarrhoea and dehydration. The basis of signs and symptomology is easily recognisable owing to the stages of progression through the human stem-cell transplantation process. Oncology nurses are in a prime position to identify these serious risks, initiate treatment immediately and collaborate effectively within the multidisciplinary team to minimise GvHD onset and provide expert support to patients, family and caregivers.
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The synthesis of thiophene-containing second (G2) and third generation (G3) dendronized macromonomers with methacrylate polymerizable units as well as their corresponding dendronized polymers is reported. The dendrons are prepared from branched thiophene oligomers and are decorated with straight alkyl chains for solubility reasons. The polymerization reactions were done with AIBN as initiator and the polymers were characterized by NMR spectroscopy, elemental analysis and GPC. Molar masses are in the range of 2.2-5.4 × 105 g mol-1 (G2) and 1.3-3.0 × 104 g mol-1 (G3) for different runs. These polymers are investigated by cyclic voltammetry and optical spectroscopy.
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New push-pull copolymers based on thiophene (donor) and benzothiadiazole (acceptor) units, poly[4,7-bis(3-dodecylthiophene-2-yl) benzothiadiazole-co- thiophene] (PT3B1) and poly[4,7-bis(3-dodecylthiophene-2-yl) benzothiadiazole-co-benzothiadiazole] (PT2B2), are designed and synthesized via Stille and Suzuki coupling routes respectively. Gel permeation chromatography shows the number average molecular weights are 31100 and 8400 g mol-1 for the two polymers, respectively. Both polymers have shown absorption throughout a wide range of the UV-vis region, from 300 to 650 nm. A significant red shift of the absorption edge is observed in thin films compared to solution of the copolymers; the optical band gap is in the range of 1.7 to 1.8 eV. Cyclic voltammetry indicates reversible oxidation and reduction processes with HOMO energy levels calculated to be in the range of 5.2 to 5.4 eV. Upon testing both materials for organic field-effect transistors (OFETs), PT3B1 showed a hole mobility of 6.1 × 10-4 cm2 V-1 s -1, while PT2B2 did not show any field effect transport. Both copolymers displayed a photovoltaic response when combined with a methanofullerene as an electron acceptor. The best performance was achieved when the copolymer PT3B1 was blended with [70]PCBM in a 1:4 ratio, exhibiting a short-circuit current of 7.27 mA cm-2, an open circuit voltage of 0.85 V, and a fill factor of 41% yielding a power conversion efficiency of 2.54% under simulated air mass (AM) 1.5 global (1.5 G) illumination conditions (100 mW cm-2). Similar devices utilizing PT2B2 in place of PT3B1 demonstrated reduced performance with a short-circuit current of 4.8 mA cm -2, an open circuit voltage of 0.73 V, and a fill factor of 30% resulting in a power conversion efficiency of roughly 1.06%.
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This work was choreographed for Expressions Dance Company as part of their inaugurals season The Dance Makers Season to launch the work of the company’s new artistic director, Natalie Weir. It was also toured throughout North Queensland.
Understanding the mechanisms of graft union formation in solanaceae plants using in vitro techniques
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Conducting polymers have become the focus of research due to their interesting properties, such as a wide range of conductivity, facile production, mechanical stability, light weight and low cost and due to the ease with which conducting polymers can be nanostructured to meet the specific application. They have become valuable materials for many applications, such as energy storage and generation. Recently, conducting polymers have been studied to be used in supercapacitors, battery electrode and fuel cells. This article is to briefly discuss the background & theory behind their conductivity as well as to highlight the recent contributions of conducting polymers to the field of energy and their significance. Furthermore, the methods of production of the conducting polymers in addition to the different ways utilised to nano-engineer special morphologies are discussed.
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Abstract: A strategy that is often used for designing low band gap polymers involves the incorporation of electron-rich (donor) and electron-deficient (acceptor) conjugated segments within the polymer backbone. In this paper we investigate such a series of Diketopyrrolopyrrole (DPP)-based co-polymers. The co-polymers consisted of a DPP unit attached to a phenylene, naphthalene, or anthracene unit. Additionally, polymers utilizing either the thiophene-flanked DPP or the furan-flanked DPP units paired with the naphthalene comonomer were compared. As these polymers have been used as donor materials and subsequent hole transporting materials in organic solar cells, we are specifically interested in characterizing the optical absorption of the hole polaron of these DPP based copolymers. We employ chemical doping, electrochemical doping, and photoinduced absorption (PIA) studies to probe the hole polaron absorption spectra. While some donor-acceptor polymers have shown an appreciable capacity to generate free charge carriers upon photoexcitation, no polaron signal was observed in the PIA spectrum of the polymers in this study. The relations between molecular structure and optical properties are discussed. Keywords: organic solar cell; organic photovoltaic; diketopyrrolopyrrole; chemical doping; spectroelectrochemistry; photoinduced absorption; hole polaron
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Recent research in posttraumatic growth has been applied to people with life-threatening illnesses to optimise recovery. There is a lack of research exploring posttraumatic growth in coronary artery bypass graft patients. This article describes the recovery experience of 14 coronary artery bypass graft patients (13 males and 1 female) at their first outpatient review post-surgery. Grounded theory analysis was used to develop a model of distinct and shared pathways to growth depending on whether patients were symptomatic or asymptomatic pre-coronary artery bypass graft. Outcomes of posttraumatic growth in this sample included action-based healthy lifestyle growth and two forms of cognitive growth: appreciation of life and new possibilities. The model of posttraumatic growth developed in this study may be helpful in guiding future research into promoting posttraumatic growth and behaviour change in coronary artery bypass graft patients.
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Background: Multipotent mesenchymal stromal cells suppress T-cell function in vitro, a property that has underpinned their use in treating clinical steroid-refractory graft-versus-host disease after allogeneic hematopoietic stem cell transplantation. However the potential of mesenchymal stromal cells to resolve graft-versus-host disease is confounded by a paucity of pre-clinical data delineating their immunomodulatory effects in vivo. Design and Methods: We examined the influence of timing and dose of donor-derived mesenchymal stromal cells on the kinetics of graft-versus-host disease in two murine models of graft-versus-host disease (major histocompatibility complex-mismatched: UBI-GFP/BL6 [H-2b]→BALB/c [H-2d] and the sibling transplant mimic, UBI-GFP/BL6 [H-2b]→BALB.B [H-2b]) using clinically relevant conditioning regimens. We also examined the effect of mesenchymal stromal cell infusion on bone marrow and spleen cellular composition and cytokine secretion in transplant recipients. Results: Despite T-cell suppression in vitro, mesenchymal stromal cells delayed but did not prevent graft-versus-host disease in the major histocompatibility complex-mismatched model. In the sibling transplant model, however, 30% of mesenchymal stromal cell-treated mice did not develop graft-versus-host disease. The timing of administration and dose of the mesenchymal stromal cells influenced their effectiveness in attenuating graft-versus-host disease, such that a low dose of mesenchymal stromal cells administered early was more effective than a high dose of mesenchymal stromal cells given late. Compared to control-treated mice, mesenchymal stromal cell-treated mice had significant reductions in serum and splenic interferon-γ, an important mediator of graft-versus-host disease. Conclusions: Mesenchymal stromal cells appear to delay death from graft-versus-host disease by transiently altering the inflammatory milieu and reducing levels of interferon-γ. Our data suggest that both the timing of infusion and the dose of mesenchymal stromal cells likely influence these cells’ effectiveness in attenuating graft-versus-host disease.
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Background Preparative myeloablative conditioning regimens for allogeneic hematopoietic stem-cell transplantation (HSCT) may control malignancy and facilitate engraftment but also contribute to transplant related mortality, cytokine release, and acute graft-versus-host disease (GVHD). Reduced intensity conditioning (RIC) regimens have decreased transplant related mortality but the incidence of acute GVHD, while delayed, remains unchanged. There are currently no in vivo allogeneic models of RIC HSCT, limiting studies into the mechanism behind RIC-associated GVHD. Methods We developed two RIC HSCT models that result in delayed onset GVHD (major histocompatibility complex mismatched (UBI-GFP/BL6 [H-2b]→BALB/c [H-2d]) and major histocompatibility complex matched, minor histocompatibility mismatched (UBI-GFP/BL6 [H-2b]→BALB.B [H-2b])) enabling the effect of RIC on chimerism, dendritic cell (DC) chimerism, and GVHD to be investigated. Results In contrast with myeloablative conditioning, we observed that RIC-associated delayed-onset GVHD is characterized by low production of tumor necrosis factor-α, maintenance of host DC, phenotypic DC activation, increased T-regulatory cell numbers, and a delayed emergence of activated donor DC. Furthermore, changes to the peritransplant milieu in the recipient after RIC lead to the altered activation of DC and the induction of T-regulatory responses. Reduced intensity conditioning recipients suffer less early damage to GVHD target organs. However, as donor cells engraft, activated donor DC and rising levels of tumor necrosis factor-α are associated with a later onset of severe GVHD. Conclusions Delineating the mechanisms underlying delayed onset GVHD in RIC HSCT recipients is vital to improve the prediction of disease onset and allow more targeted interventions for acute GVHD.
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Host and donor dendritic cells (DC) stimulate alloreactive donor T lymphocytes, and initiate GVHD. We have shown that polyclonal antibody to the DC surface activation marker human CD83 (anti hCD83), which depletes activated DC, can prevent human DC and T cell induced lethal xenogeneic GVHD in SCID mice without impairing T cell mediated anti-leukaemic and anti-viral (CMV and influenza) immunity (J Exp Med 2009; 206: 387). Therefore, we made and tested a polyclonal anti mouse CD83 (RAM83) antibody in murine HSCT models and developed a human mAb against hCD83 as a potential new therapeutic immunosuppressive agent.
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The structures of the ammonium salts of phenoxyacetic acid, NH4+ C8H6O3- (I), (4-fluorophenoxy)acetic acid NH4+ C8H5FO3- (II) and the herbicidally active (4-chloro-2-methylphenoxy)acetic acid (MCPA), NH4+ C9H8ClO3-. 0.5(H2O) (III) have been determined. All have two-dimensional layered structures based on inter-species ammonium N-H...O hydrogen-bonding associations which give core substructures consisting primarily of conjoined cyclic motifs. Crystals of (I) and (II) are isomorphous with the core comprising R2/1(5), R2/1(4) and centrosymmetric R2/4(8) ring motifs, giving two-dimensional layers lying parallel to (100). In (III), the water molecule of solvation lies on a crystallographic twofold rotation axis and bridges two carboxyl O-atoms in an R4/4(12) hydrogen-bonded motif, creating two R3/4(10) rings which together with a conjoined centrosymmetric R2/4(8) ring incorporating both ammonium cations, generate two-dimensional layers lying parallel to (100). No pi-pi ring associations are present in any of the structures.
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BACKGROUND After general surgery, the lower limb experiences some of the highest complication rates. However, little is known about contributing factors to surgical site failure in the lower limb dermatological surgery population. OBJECTIVE To determine the incidence of lower limb surgical site failure and to explore the predictors that contribute to surgical site failure. METHODS A prospective observational study design was used to collect data from 73 participants, from July 2010, to March 2012. Incidence was determined as a percentage of surgical site failure from the total population. Predictors were determined by the use of a binary logistic regression model. RESULTS The surgical site failure rate was 53.4%. Split-skin grafting had a higher failure rate than primary closures, 66% versus 26.1%. Predictors of lower limb surgical site failure were identified as increasing age (p = .04) and the presence of postoperative hematoma (p = .01), with all patients who developed surgical site infection experiencing surgical site failure (p = .01). CONCLUSION Findings from this study confirmed that the lower limb is at high risk of surgical site failure. Two predictors of surgical site failure from this cohort were determined. However, to understand this phenomenon and make recommendations to assist and reduce surgical site complications, further research in this field is required.