Hepatocellular protection by nitric oxide or nitrite in ischemia and reperfusion injury

Ischemia and reperfusion (I/R)-induced liver injury occurs in several pathophysiological disorders including hemorrhagic shock and burn as well as resectional and transplantation surgery. One of the earliest events associated with reperfusion of ischemic liver is endothelial dysfunction characterized by the decreased production of endothelial cell-derived nitric oxide (NO). This rapid post-ischemic decrease in NO bioavailability appears to be due to decreased synthesis of NO, enhanced inactivation of NO by the overproduction of superoxide or both. This review presents the most current evidence supporting the concept that decreased bioavailability of NO concomitant with enhanced production of reactive oxygen species initiates hepatocellular injury and that endogenous NO or exogenous NO produced from nitrite play important roles in limiting post-ischemic tissue injury

Evaluación de variantes genéticas y filogenia de la pera común (Pyrus communis L.) cultivada en la ciudad Duhok empleando AFLP como marcadores moleculares

Introduction: Genotyping and evaluation of genetic variation and polymorphic information content of the locally cultivated pear (Pyrus communis L.) might play an important role in building the genetic bank. These are also immensely important for present and future pear breeding program in the region. Methods: In the current study, AFLP markers have been employed to estimate the level of genetic diversity and to assess the phylogeny among theseven most popular pear cultivars in Duhok city. Results: Eight selective primer combinations generated a total of 653 AFLP fragments from which 445 (68.2%) fragments were polymorphic. The number of visible amplified products per primer combination were varied and ranged from 66 to 96 bands. The highestpercentage of polymorphism (78.4%) was observed by the primer pair P174/M182, while the lowest percentage of polymorphism (58.6%) was observed by the primer pair P174/M100. The highest PIC (0.85) was obtained with the primer combination P174/ M182, while, the lowest PIC (0.49) was obtained by the primer combination P174/M307. The genetic distance was ranged from 0.1348 (between Danimarki and Amreki cultivars) to 0.3131 (between Italy and Zaafaran2 cultivars). Based on the AFLP data, all the seven pear genotypes were successfully clustered into two separate clusters (C1 and C2) with an out-group of Itali cultivar. Conclusions: Overall, it can be concluded that there was high polymorphism among the studied genotypes. Also, it can be stated that the AFLP was a reliable and a powerful technique in genotyping and discriminating of respective pear cultivars

ESTIMATION VARIABILITY AND SOME GENETIC PARAMETERS FOR YIELD AND ITS COMPONENTS IN PEA GENOTYPES UNDER DIFFERENT PHOSPHOROUS LEVELS.

This study aimed to estimate variability and some genetic parameters for yield and yield components in pea (Pisum sativum L.) genotypes under different phosphorous levels. A field experiment was carried out at the field of Horticulture Department, College of Agricultural Engineering Sciences, Duhok University, on the 1st of November 2021. the experiment unites layout according to split-plot arrangement, the main plots include phosphorus levels (0, 18, 36, and 54 kg ha-1 P2O5 and the subplot represented the thirteen genotypes within RCBD. The results exhibited that phosphorus levels were highly significant for all traits except biological yield, also the genotypes show highly significant the with exception of harvest index, while the interaction between phosphorus levels and genotypes was highly significant for all studied traits except harvest index and pod length. The rate of 54 kg ha-1 P2O5 gave the highest value for the number of pods 281.359), length pod 3.94, 500 seed weight 86.54, biological yield 361.55, harvest index 10.82 and yield seed per plant 23.30. The local variety was superior in leaf area 808.08mm, length pod 10 cm, 500 seeds weight 25.369, also the genotype (1) gave the highest yield per plant 44.0367 kg ha-1 P2O5, for the interaction between genotypes and phosphorus levels of genotype (2)

Mouse model of liver ischemia and reperfusion injury: method for studying reactive oxygen and nitrogen metabolites in vivo

The mouse model of liver ischemia and reperfusion injury has proven to be valuable for our understanding of the role that reactive oxygen and nitrogen metabolites play in postischemic tissue injury. This methods paper provides a detailed protocol for inducing partial liver ischemia followed by reperfusion. Liver ischemia is induced in anesthetized mice by cross-clamping the hepatic artery and portal vein for varying lengths of time resulting in deprivation of blood flow to approximately of 70% of the liver. Restoration of blood flow to the ischemic lobes enhances superoxide production concomitant with a rapid and marked decrease in the bioavailability of nitric oxide resulting in alterations in the redox state of the liver in favor of a more oxidative environment. This hepatocellular oxidative stress induces the activation of oxidant-sensitive transcription factors followed by the upregulation of pro-inflammatory cytokines and mediators that ultimately lead to liver injury. This model can be induced in any strain or sex of mouse and requires 1-2 months of practice to become proficient in the surgery and animal manipulation. The role of different reactive metabolites of oxygen and nitrogen may be evaluated using genetically-engineered mice as well as selective molecular, cellular and/or pharmacological agents

Induction of Foxp3-Expressing Regulatory T-Cells by Donor Blood Transfusion Is Required for Tolerance to Rat Liver Allografts

BACKGROUND:Donor-specific blood transfusion (DST) prior to solid organ transplantation has been shown to induce long-term allograft survival in the absence of immunosuppressive therapy. Although the mechanisms underlying DST-induced allograft tolerance are not well defined, there is evidence to suggest DST induces one or more populations of antigen-specific regulatory cells that suppress allograft rejection. However, neither the identity nor the regulatory properties of these tolerogenic lymphocytes have been reported. Therefore, the objective of this study was to define the kinetics, phenotype and suppressive function of the regulatory cells induced by DST alone or in combination with liver allograft transplantation (LTx). METHODOLOGY/PRINCIPAL FINDINGS:Tolerance to Dark Agouti (DA; RT1(a)) rat liver allografts was induced by injection (iv) of 1 ml of heparinized DA blood to naïve Lewis (LEW; RT1(l)) rats once per week for 4 weeks prior to LTx. We found that preoperative DST alone generates CD4(+) T-cells that when transferred into naïve LEW recipients are capable of suppressing DA liver allograft rejection and promoting long-term survival of the graft and recipient. However, these DST-generated T-cells did not express the regulatory T-cell (Treg) transcription factor Foxp3 nor did they suppress alloantigen (DA)-induced activation of LEW T-cells in vitro suggesting that these lymphocytes are not fully functional regulatory Tregs. We did observe that DST+LTx (but not DST alone) induced the time-dependent formation of CD4(+)Foxp3(+) Tregs that potently suppressed alloantigen-induced activation of naïve LEW T-cells in vitro and liver allograft rejection in vivo. Finally, we present data demonstrating that virtually all of the Foxp3-expressing Tregs reside within the CD4(+)CD45RC(-) population whereas in which approximately 50% of these Tregs express CD25. CONCLUSIONS/SIGNIFICANCE:We conclude that preoperative DST, in the absence of liver allograft transplantation, induces the formation of CD4(+) T-cells that are not themselves Tregs but give rise directly or indirectly to fully functional CD4(+)CD45RC(-)Foxp3(+)Tregs when transferred into MHC mismatched recipients prior to LTx. These Tregs possess potent suppressive activity and are capable of suppressing acute liver allograft rejection. Understanding the mechanisms by which preoperative DST induces the generation of tolerogenic Tregs in the presence of alloantigens may lead to the development of novel antigen-specific immunological therapies for the treatment of solid organ rejection

An Early Study on the Mechanisms that Allow Tissue-Engineered Vascular Grafts to Resist Intimal Hyperplasia

Intimal hyperplasia is one of the prominent failure mechanisms for arteriovenous fistulas and arteriovenous access grafts. Human tissue-engineered vascular grafts (TEVGs) were implanted as arteriovenous grafts in a novel baboon model. Ultrasound was used to monitor flow rates and vascular diameters throughout the study. Intimal hyperplasia in the outflow vein of TEVGs was assessed at the anastomosis and at juxta-anastomotic regions via histological analysis, and was compared to intimal hyperplasia with polytetrafluoroethylene (PTFE) grafts in the baboon model and in literature reports from other animal models. Less venous intimal hyperplasia was observed in histological sections with arteriovenous TEVGs than with arteriovenous PTFE grafts. TEVGs were associated with a mild, noninflammatory intimal hyperplasia. The extent of intimal tissue that formed with TEVG placement correlated with the rate of blood flow through tissue engineered vascular grafts at 2 weeks postimplant. Outflow vein dilatation was observed with increased flow rate. Both mid-graft flow rates and outflow vein diameters reached a plateau by week 4, which suggested that venous remodeling and intimal hyperplasia largely occurred within the first 4 weeks of implant in the baboon model. Given their compliant and noninflammatory nature, TEVGs appear resistant to triggers for venous intimal hyperplasia that are common for PTFE arteriovenous grafts, including (1) abundant proinflammatory macrophage populations that are associated with PTFE grafts and (2) compliance mismatch between PTFE grafts and the outflow vein. Our findings suggest that arteriovenous TEVGs develop only a mild form of venous intimal hyperplasia, which results from the typical hemodynamic changes that are associated with arteriovenous settings