Systemic administration of the inhibitor of costimulation, CTLA4Ig, has been shown to prolong islet graft survival. The purpose of this study was to compare local and systemic expression of murine ...CTLA4Ig in transplants of rat islets into mice.
Murine CTLA4Ig was made by joining two polymerase chain reaction products, the extracellular portion of CTLA4 and the Fc portion of IgG2a. Recombinant adenovirus expressing CTLA4Ig (AdCTLA4Ig) was generated using the strategy of Cre-lox recombination. Isolated rat islets infected with AdCTLA4Ig at multiplicities of infection (MOIs) ranging from 0.1 to 10 were transplanted into streptozocin diabetic male B6AF1 mice. Control islets were mock infected or infected with AdLacZ or AdsIg, a recombinant adenovirus expressing only the Fc portion of IgG2a. Also, AdCTLA4Ig and control viruses were injected intramuscularly into mouse transplant recipients at the time of islet transplantation to provide CTLA4Ig systemically.
Control islets transplanted into diabetic mice were rejected in 13-17 days. Islets infected with AdCTLA4Ig had dose-dependent prolongation of graft survival. Prolonged survival was even found with very low MOIs of 0.1 and 0.5, with survivals of 24+/-4.2 and 25+/-2.2 days, respectively. Survival with an MOI of 10 was 39+/-8.7 days. With intramuscular injection, no prolongation was found at the lowest relative MOIs of 0.2 and 1, but there was dose-dependent prolongation of graft survival with larger doses. At the highest relative MOI of 400, survival was prolonged to 58+/-10 days.
Rat islets infected with AdCTLA4Ig transplanted into mice had prolonged graft survival. Prolonged survival with MOIs as low as 0.1 and 0.5 indicates that only a minority of islet cells need to express CTLA4Ig to exert an effect. Moreover, the results suggest that the improved islet graft survival is due to a local influence of CTLA4Ig.
The present study investigates the polymer surface changes when the incident ion energy is increased to levels comparable to conventional, low pressure plasma discharges (20 eV). This allows for a ...study of polar groups incorporation, topography, and surface energy analysis over a range of ion energies not easily achieved in plasmas. The use of inert gas environments (Ar) would permit us to compare the influence of ion energy, while the addition of reactive gases (02) adds a chemical component to the studies.
4-Aminophenol (p-aminophenol, PAP) causes selective necrosis to the pars recta of the proximal tubule in Fischer 344 rats. The basis for this selective toxicity is not known, but PAP can undergo ...oxidation in a variety of systems to form the 4-aminophenoxy free radical. Oxidation or disproportionation of this radical will form 1,4-benzoquinoneimine which can covalently bind to tissue macromolecules. Recent studies have shown that certain benzoquinol-glutathione conjugates can cause renal necrosis in rats. We have synthesized a putative glutathione conjugate of PAP. The effect on the kidney of this conjugate and the sulphate and N-acetyl conjugates, known metabolites of PAP, have been examined in Fischer 344 rats. 4-Amino-3-S-glutathionylphenol produced a dose-dependent (92-920 μmol kg-1) necrosis of the proximal tubular epithelium and altered renal excretory function. The lesion at the low dose was restricted to the pars recta of the proximal tubule in the medullary rays, while at the higher doses it affected the pars recta region of all nephrons. In contrast, PAP-o-sulphate and N-acetyl-4-aminophenol (paracetamol) caused no histological or functional alteration to the kidney at 920 μmol kg-1. The renal necrosis produced by 4-amino-3-S-glutathionylphenol was very similar to that produced by PAP (367-920 μmol kg-1), both functionally and histologically, except that smaller doses of the glutathione conjugate were required. These studies indicate that glutathione conjugation of PAP generates a metabolite that is more toxic to the kidney than the parent compound. A possible mechanism of toxicity (analogous to that reported for glutathione conjugates of certain quinones) involving oxidation to form a 1,4-benzoquinoneimine thioether that could redox cycle is discussed.
Background. A major problem facing islet transplantation is immune destruction of grafts by transplant rejection and autoimmunity. Some success in prolonging graft rejection has been obtained by ...transducing islets prior to transplantation with adenoviral (Ad) vectors containing CTLA4-Ig and TGFβ. The purpose of this study was to see if lentiviral (LV) vectors would provide superior results compared with adenoviral vectors.
Methods. Islets were isolated from Sprague–Dawley rats and transduced with Ad or LV vectors containing LacZ, CTLA4-Ig, CTLA4, and TGFβ1 using various MOIs. Islets transduced with LV were healthy as judged by DNA and insulin content, and insulin secretion. Using the kidney capsule transplant site, 500 transduced rat islets were transplanted into streptozotocin diabetic B6AF1 mice.
Results. Maintenance of normoglycemia was prolonged in recipient mice carrying islets transduced with Ad vectors containing CTLA4-Ig, CTLA4, and TGFβ1. Return of hyperglycemia in controls was 17–18 days while loss of function for the experimental groups occurred at 20–27 days. For the lentivirus transduced islets, rejection of controls was 20±1.6 days, for CTLA4-Ig was 42±21 days and for TGFβ was 28±3.2 days.
Conclusions. Although islets transduced with either adenovirus or lentivirus containing CTLA4-Ig, CTLA4, and TGFβ1 could prolong graft survival in a rat to mouse transplantation model, with the conditions of this study lentivirus provided no advantage over adenovirus vectors.
Summary form only given. The NRL electron beam-generated plasma source uses magnetically collimated sheet-like beam of high energy electrons to ionize the gas, providing control over critical plasma ...parameters including plasma density, ionization region, electron temperature, ion and radical fluxes. Perhaps, the most important advantages of the system are its inherently low electron temperature, typically below 1 eV, resulting in very low incident ion kinetic energies at adjacent surfaces, thereby providing unique opportunities in the processing of ion energy-sensitive materials, e.g. polymers and graphene. However, there remain many unresolved questions regarding the mechanisms of surface modifications induced by electron beam-generated plasmas, most notably, the influence of excited species. In this work, we apply optical emission spectroscopy in order to understand the spatial and temporal distribution of excited species in pure argon, nitrogen and their mixtures.
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