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X X Peng

Publications and source records attributed to X X Peng.

26 records · Page 2Linked to original sources

Immunoglobulin and complement complexes in blood following infection with human immunodeficiency virus type 1.

Freely soluble and complexed plasma immunoglobulin A (IgA), IgG, IgM, C1q, C3, and factor B in 36 human immunodeficiency virus type I (HIV-1)-seronegative controls, 69 asymptomatic HIV+ subjects, and 117 individuals with symptomatic HIV-associated disease were characterized. Levels of free and complexed IgG and IgA, and to a lesser extent free C1q and complexed IgM, increased with HIV-1 infection. In stark contrast, both HIV+ groups showed three- to sixfold declines in complexed C3, C1q, and factor B levels. The asymptomatic HIV+ population showed declines in levels of C3-bound IgA, IgG2, and IgG4 complexes. The asymptomatic group showed reductions in C3-complexed IgM, IgA, IgG2, and IgG4 levels. HIV infection is associated with complement-deficient immune complexes.

Antigen-Antibody Complex↗

Protection by pentoxifylline against normothermic liver ischemia/reperfusion in rats.

Previously, pentoxifylline treatment of graft recipients was shown to protect against liver graft failure from storage/reperfusion injury after orthotopic rat liver transplantation. To determine whether pentoxifylline also protects against normothermic ischemia/reperfusion injury to liver, we induced lobar ischemia in rats followed by reflow and partial hepatectomy of the noninvolved liver. In rats receiving pentoxifylline 2 hr before surgery and then twice daily for 5 days, the 1-week survival rate more than doubled from 25% to 67% (P < 0.05). Liver enzymes (alanine transaminase, aspartate transaminase, and lactate dehydrogenase) in the serum and liver necrosis evaluated histologically were also significantly reduced in the pentoxifylline-treated rats (P < 0.01). Hepatic ischemia/reperfusion increased leukocyte infiltration into the lungs, and pentoxifylline tended to reduce this lung injury (P = 0.06). These results show that pentoxifylline treatment reduces hepatic injury and improves survival after normothermic ischemia and reperfusion.

Animals↗

Dual role of Kupffer cell activation and endothelial cell damage in reperfusion injury to livers stored for transplantation surgery.

In rat models of liver preservation, the primary event leading to liver graft failure after cold storage is a reperfusion injury causing damage to sinusoidal endothelial cells and activation of Kupffer cells (KC). After storage for longer than 16 h in University of Wisconsin solution, reperfusion induces rapid endothelial cell killing. Kupffer cell activation also occurs as indicated by cell surface ruffling, degranulation, release of hydrolytic enzymes, generation of oxygen radicals, and increased phagocytosis. Down-regulation of KC activity with nisoldipine or pentoxifylline improves graft survival. Moreover, pretreatment of donors with small amounts of endotoxin to activate KC causes a drastic reduction of graft survival. Together, KC activation and endothelial damage cause marked microcirculatory disturbances after transplantation characterized by reduced and uneven blood flow and increased leucocyte and platelet adhesion. Such events culminate in inflammation, necrosis and fulminant graft failure. Modification of reperfusion conditions can reduce the extent of injury. In particular, flushing livers with Carolina rinse solution (CRS) at the end of storage reduces endothelial cell killing, suppresses KC activation, improves the microcirculation, and increases graft survival. Active ingredients in CRS include antioxidants (allopurinol, desferrioxamine and glutathione), adenosine and slightly acidic pH (6.5). Other potentially important ingredients are nicardipine, a calcium channel blocker, and fructose, glucose and insulin to promote glycolysis. The cytoprotective amino acid, glycine, further improves the performance of Carolina rinse solution. Reperfusion-induced changes to nonparenchymal cells play an essential role in damage to livers preserved for transplantation surgery. Understanding the role of sinusoidal endothelial cells and KC in this injury has led to promising new strategies to prolong organ storage and reduce graft failure.

Animals↗

[The role of pentoxifylline in acute lung injury complicated by pancreatitis].

Caerulein-induced acute pancreatitis in rats commonly complicated ARDS-like acute lung injury. Acute pancreatitis induced by caerulein in the circulating neutrophil-depleted rat by hydroxyrea or with the administration of SOD, CAT or Pentoxifylline, the wet lung weight, lung capillary endothelial permeability decrease significantly compared to the caerulein group (P < 0.05). There are no lung morphologic evidences of neutrophil sequestration, interstial edema, intralveolar hemorrhage that seen in caerulein infusion animals. But it has no effect against the development of acute pancreatitis. It suggested that neutrophil and neutrophil-derived oxygen radical are the important mediators of acute lung injury complicated by pancreatitis.

Animals↗

Expression of the protease gene of equine infectious anemia virus in Escherichia coli: formation of the mature processed enzyme and specific cleavage of the gag precursor.

A 620-bp Bg/II restriction fragment containing the putative protease coding sequence from equine infectious anemia virus (EIAV) proviral DNA was cloned and expressed in E. coli as a Pol precursor protein. In contrast to the 25-kDa fusion protein predicted from the expressed pol sequence, a protein of approximately 10 kDa was generated by apparent autocatalytic processing of the Pol precursor. This mature processed protein was detected in transformed cells using an antisera raised against synthetic peptide from the conserved carboxyl-terminal segment of the predicted EIAV protease coding sequence. Coexpression of this protein with a 35-kDa EIAV Gag-precursor fusion protein resulted in the specific proteolytic processing of the precursor as shown by formation of p26, the major capsid protein of EIAV.

Cloning, Molecular↗

Proteolytic processing of the proteins translated from the bottom component RNA of cowpea mosaic virus. The primary and secondary cleavage reactions.

The products of translation of cowpea mosaic virus B-RNA in rabbit reticulocyte lysates are proteolytically cleaved to form a specific set of proteins. The primary cleavage occurs as nascent peptide chains elongate to a size of about 150 kilodaltons yielding a 32K protein and, upon chain completion, a 170K protein. This cleavage reaction is inhibited by 3 mM iodoacetamide. The 170K protein, in turn, is cleaved to yield either of two pairs of proteins, a 110K and 60K pair or a 87K and 84K pair. The reaction for forming the 110K-60K pair is sensitive to dilution, indicating that a free factor is involved. The reaction for forming the 87K-84K pair, on the other hand, is not affected by diluting the lysate reaction mixture with buffer even to 200-fold, indicating that the reaction is autolytic. Formation of the 110K-60K pair, but not the 87K-84K pair, is inhibited by 2 mM zinc chloride. Translational mapping data indicate that the 87K and 60K proteins are derived from the NH2-terminal side of the 170K protein.

Animals↗