J. Anthony Thompson

Oxygen radical inhibition of nitric oxide-dependent vascular function in sickle cell disease

Plasma xanthine oxidase (XO) activity was defined as a source of enhanced vascular superoxide (O\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \setlength{\oddsidemargin}{-69pt} \begin{document} \begin{equation*}{\mathrm{_{2}^{{\cdot}-}}}\end{equation*}\end{document}) and hydrogen peroxide (H2O2) production in both sickle cell disease (SCD) patients and knockout-transgenic SCD mice. There was a significant increase in the plasma XO activity of SCD patients that was similarly reflected in the SCD mouse model. Western blot and enzymatic analysis of liver tissue from SCD mice revealed decreased XO content. Hematoxylin and eosin staining of liver tissue of knockout-transgenic SCD mice indicated extensive hepatocellular injury that was accompanied by increased plasma content of the liver enzyme alanine aminotransferase. Immunocytochemical and enzymatic analysis of XO in thoracic aorta and liver tissue of SCD mice showed increased vessel wall and decreased liver XO, with XO concentrated on and in vascular luminal cells. Steady-state rates of vascular O\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \setlength{\oddsidemargin}{-69pt} \begin{document} \begin{equation*}{\mathrm{_{2}^{{\cdot}-}}}\end{equation*}\end{document} production, as indicated by coelenterazine chemiluminescence, were significantly increased, and nitric oxide (⋅NO)-dependent vasorelaxation of aortic ring segments was severely impaired in SCD mice, implying oxidative inactivation of ⋅NO. Pretreatment of aortic vessels with the superoxide dismutase mimetic manganese 5,10,15,20-tetrakis(N-ethylpyridinium-2-yl)porphyrin markedly decreased O\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \setlength{\oddsidemargin}{-69pt} \begin{document} \begin{equation*}{\mathrm{_{2}^{{\cdot}-}}}\end{equation*}\end{document} levels and significantly restored acetylcholine-dependent relaxation, whereas catalase had no effect. These data reveal that episodes of intrahepatic hypoxia-reoxygenation associated with SCD can induce the release of XO into the circulation from the liver. This circulating XO can then bind avidly to vessel luminal cells and impair vascular function by creating an oxidative milieu and catalytically consuming ⋅NO via O\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \setlength{\oddsidemargin}{-69pt} \begin{document} \begin{equation*}{\mathrm{_{2}^{{\cdot}-}}}\end{equation*}\end{document}-dependent mechanisms.

Estrogen-Induced Vasoprotection Is Estrogen Receptor Dependent Evidence From the Balloon-Injured Rat Carotid Artery Model

BACKGROUND Previous studies have shown that estrogen (E2) is vasoprotective in multiple animal models of vascular injury, including mice with homologous disruptions of either the alpha or beta isoforms of the estrogen receptor (ER) gene, calling into question the ER dependency of the vasoprotective effect. This study used ICI 182,780, a nonselective ER antagonist, to test the hypothesis that the vasoprotective effect of E2 in the rat carotid injury model is ER mediated. METHODS AND RESULTS Intact female Sprague-Dawley rats were divided into 4 groups and treated with the nonselective ER antagonist ICI 182,780 (ICI; 0.5, 1.5, or 5 mg. kg(-1). d(-1), subcutaneously [S.C.]) or vehicle, beginning before balloon injury of the right common carotid artery and continuing for 14 days afterward. Four groups of ovariectomized rats (OVX) were treated with 17beta estradiol (E2) (20 microgram. kg(-1). d(-1), S.C.) alone or combined with ICI 5 mg. kg(-1). d(-1), S.C.; with ICI 5 mg. kg(-1). d(-1) alone; or with vehicle according to a similar protocol. Two weeks after injury, rats were killed, and the carotid arteries were evaluated for neointima formation using morphometric analysis. ICI 182,780 blunted the E2-related protective effect and increased neointima formation in injured carotid arteries of intact female rats in a dose-dependent fashion. ICI had no effect on neointima formation in OVX, but addition of ICI to E2 in OVX blocked the inhibitory effect of exogenous E2 on neointima formation. CONCLUSIONS These results indicate that the vasoprotective effect of E2 in the balloon-injured rat carotid artery model is mediated by ER.

Improved outcomes in cadaveric renal allografts with pulsatile preservation

Background: Early immunologic and non‐immunologic injury of renal allografts adversely affects long‐term graft survival. Some degree of preservation injury is inevitable in cadaveric renal transplantation, and, with the reduction in early acute rejection, this non‐immunologic injury has assumed a greater relative importance. Optimal graft preservation will maximize the chances of early graft function and long‐term graft survival, but the best method of preservation – pulsatile perfusion (PP) versus cold storage (CS) – is debated. 
Methods: Primary cadaveric kidney recipients from January 1990 through December 1995 were evaluated. The effects of implantation warm ischemic time (WIT) (≤20 min, 21–40 min, or >40 min) and total ischemic time (TIT) (< or ≥20 h) on death‐censored graft survival were compared between kidneys preserved by PP versus those preserved by CS. The effect of preservation method on delayed graft function (DGF) was also examined. 
Results: There were 568 PP kidneys and 268 CS kidneys. Overall death‐censored graft survival was not significantly different between groups, despite worse donor and recipient characteristics in the PP group. CS kidneys with an implantation WIT >40 min had worse graft survival than those with <40 min (p=0.0004). Survival of PP kidneys and those transplanted into 2 DR‐matched recipients was not affected by longer implantation WIT. Longer TIT did not impact survival. DGF was more likely after CS preservation (20.2% versus 8.8%, p=0.001). 
Conclusions: Preservation with PP improves early graft function and lessens the adverse effect of increased warm ischemia in cadaveric renal transplantation. This method is likely associated with less preservation injury and/or increases the threshold for injury from other sources and is superior to CS.