Hypercoagulability progresses to hypocoagulability during evolution of acetaminophen-induced acute liver injury in pigs

Increases in prothrombin time (PT) and international normalised ratio (INR) characterise acute liver injury (ALI) and failure (ALF), yet a wide heterogeneity in clotting abnormalities exists. This study defines evolution of coagulopathy in 10 pigs with acetaminophen (APAP)-induced ALI compared to 3 Controls. APAP administration began at 0 h and continued to ‘ALF’, defined as INR >3. In APAP pigs, INR was 1.05 ± 0.02 at 0 h, 2.15 ± 0.43 at 16 h and > 3 at 18 ± 1 h. At 12 h thromboelastography (TEG) demonstrated increased clot formation rate, associated with portal vein platelet aggregates and reductions in protein C, protein S, antithrombin and A Disintegrin and Metalloprotease with Thrombospondin type 1 repeats–13 (ADAMTS-13) to 60%, 24%, 47% and 32% normal respectively. At 18 ± 1 h, INR > 3 was associated with: hypocoagulable TEG profile with heparin-like effect; falls in thrombin generation, Factor V and Factor VIII to 52%, 19% and 17% normal respectively; further decline in anticoagulants; thrombocytopenia; neutrophilia and endotoxemia. Multivariate analysis, found that ADAMTS-13 was an independent predictor of a hypercoagulable TEG profile and platelet count, endotoxin, Protein C and fibrinogen were independent predictors of a hypocoagulable TEG profile. INR remained normal in Controls. Dynamic changes in coagulation occur with progression of ALI: a pro-thrombotic state progresses to hypocoagulability

Circulating Endothelial Progenitor Cells in Kidney Transplant Patients

Background: Kidney transplantation (RTx) leads to amelioration of endothelial function in patients with advanced renal failure. Endothelial progenitor cells (EPCs) may play a key role in this repair process. The aim of this study was to determine the impact of RTx and immunosuppressive therapy on the number of circulating EPCs. Methods: We analyzed 52 RTx patients (58613 years; 33 males, mean 6 SD) and 16 age- and gender-matched subjects with normal kidney function (57617; 10 males). RTx patients received a calcineurin inhibitor (CNI)-based (65%) or a CNI-free therapy (35%) and steroids. EPC number was determined by double positive staining for CD133/VEGFR2 and CD34/VEGFR2 by flow cytometry. Stromal cell-derived factor 1 alpha (SDF-1) levels were assessed by ELISA. Experimentally, to dissociate the impact of RTx from the impact of immunosuppressants, we used the 5/6 nephrectomy model. The animals were treated with a CNI-based or a CNI-free therapy, and EPCs (Sca+cKit+) and CD26+ cells were determined by flow cytometry. Results: Compared to controls, circulating number of CD34+/VEGFR2+ and CD133+/VEGFR2+ EPCs increased in RTx patients. There were no correlations between EPC levels and statin, erythropoietin or use of renin angiotensin system blockers in our study. Indeed, multivariate analysis showed that SDF-1 – a cytokine responsible for EPC mobilization – is independently associated with the EPC number. 5/6 rats presented decreased EPC counts in comparison to control animals. Immunosuppressive therapy was able to restore normal EPC values in 5/6 rats. These effects on EPC number were associated with reduced number of CD26+ cells, which might be related to consequent accumulation of SDF-1. Conclusions: We conclude that kidney transplantation and its associated use of immunosuppressive drugs increases the number of circulating EPCs via the manipulation of the CD26/SDF-1 axis. Increased EPC count may be associated to endothelial repair and function in these patients.

Performance related factors are the main determinants of the von Willebrand factor response to exhaustive physical exercise

Background: Physical stress triggers the endothelium to release von Willebrand Factor (VWF) from the Weibel Palade bodies. Since VWF is a risk factor for arterial thrombosis, it is of great interest to discover determinants of VWF response to physical stress. We aimed to determine the main mediators of the VWF increase by exhaustive physical exercise. Methods: 105 healthy individuals (18-35 years) were included in this study. Each participant performed an incremental exhaustive exercise test on a cycle ergometer. Respiratory gas exchange measurements were obtained while cardiac function was continuously monitored. Blood was collected at baseline and directly after exhaustion. VWF antigen (VWF:Ag) levels, VWF collagen binding (VWF:CB) levels, ADAMTS13 activity and common variations in Syntaxin Binding Protein-5 (STXBP5, rs1039084 and rs9399599), Syntaxin-2 (STX2, rs7978987) and VWF (promoter, rs7965413) were determined. Results: The median VWF:Ag level at baseline was 0.94 IU/mL [IQR 0.8-1.1] and increased with 47% [IQR 25-73] after exhaustive exercise to a median maximum VWF:Ag of 1.38 IU/mL [IQR 1.1-1.8] (p<0.0001). VWF:CB levels and ADAMTS13 activity both also increased after exhaustive exercise (median increase 43% and 12%, both p<0.0001). The strongest determinants of the VWF:Ag level increase are performance related (p<0.0001). We observed a gender difference in VWF:Ag response to exercise (females 1.2 IU/mL; males 1.7 IU/mL, p = 0.001), which was associated by a difference in performance. Genetic variations in STXBP5, STX2 and the VWF promoter were not associated with VWF:Ag levels at baseline nor with the VWF:Ag increase. Conclusions: VWF:Ag levels strongly increase upon exhaustive exercise and this increase is strongly determined by physical fitness level and the intensity of the exercise, while there is no clear effect of genetic variation in STXBP5, STX2 and the VWF promoter

Cardiomyocyte Specific Ablation of p53 Is Not Sufficient to Block Doxorubicin Induced Cardiac Fibrosis and Associated Cytoskeletal Changes

Doxorubicin (Dox) is an anthracycline used to effectively treat several forms of cancer. Unfortunately, the use of Dox is limited due to its association with cardiovascular complications which are manifested as acute and chronic cardiotoxicity. The pathophysiological mechanism of Dox induced cardiotoxicity appears to involve increased expression of the tumor suppressor protein p53 in cardiomyocytes, followed by cellular apoptosis. It is not known whether downregulation of p53 expression in cardiomyocytes would result in decreased rates of myocardial fibrosis which occurs in response to cardiomyocyte loss. Further, it is not known whether Dox can induce perivascular necrosis and associated fibrosis in the heart. In this study we measured the effects of acute Dox treatment on myocardial and perivascular apoptosis and fibrosis in a conditional knockout (CKO) mouse model system which harbours inactive p53 alleles specifically in cardiomyocytes. CKO mice treated with a single dose of Dox (20 mg/kg), did not display lower levels of myocardial apoptosis or reactive oxygen and nitrogen species (ROS/RNS) compared to control mice with intact p53 alleles. Interestingly, CKO mice also displayed higher levels of interstitial and perivascular fibrosis compared to controls 3 or 7 days after Dox treatment. Additionally, the decrease in levels of the microtubule protein α-tubulin, which occurs in response to Dox treatment, was not prevented in CKO mice. Overall, these results indicate that selective loss of p53 in cardiomyocytes is not sufficient to prevent Dox induced myocardial ROS/RNS generation, apoptosis, interstitial fibrosis and perivascular fibrosis. Further, these results support a role for p53 independent apoptotic pathways leading to Dox induced myocardial damage and highlight the importance of vascular lesions in Dox induced cardiotoxicity

バレイショ近縁種における種の分化 XIII. S.acaule X S.demissumより得た7倍雑種の染色体行動と両親ゲノムの類縁関係

中央アンデス産Acaulia群4倍種S. acaule (acl, 2n=48)とメキシコ産Demissa群6倍種S. demissum (dms, 2n=72)のゲノムの類縁関係を明らかにするために, 前者を母本として得た7倍雑種(2n=84)の還元分裂における染色体行動と稔性を調べた。以下その結果を要約する。両種間の交雑は極めて困難で, aclを母とした時のみ受粉花数当り0.02の低率で雑種が得られたにすぎない。得られた雑種は, 両親との形態的比較から, aclの非還元性卵とdmsの還元性花粉の受精に起因するものと推定された。この雑種の第1中期における染色体対合行動は甚だしく多様であったが, その対合型のモードは(12)_+(20)_+8_I, その平均対合頻度は(0.18)_V+(1.11)_+(11.73)_+(18.11)_+(7.26)_Iで, 著しく高頻度の3価形成を示す点が特徴的であった。このような対合行動はその後の染色体行動にも反映し, 第1後期では観察細胞のすべてに平均4.8の遅滞染色体がみられ, 第2中期では94%の細胞が分散染色体を示し, 数的平衡核板頻度は0.6%にすぎなかった。稔性は極めて低く, 調査花粉粒数の27%が一見正常であったが, 自殖及び戻交配のいずれにおいても全く種子を生じなかった。上記の観察結果, 特に高頻度で出現した3価染色体の成因を考察して次の知見を得た。すでにaclはAAA^aA^a, dmsはA^dA^dC_1C_1C_2C_2のゲノム型をもつことが知られているので, 当雑種のゲノム型はAAA^aA^aA^dC_1C_2となる。A^dゲノムは若干の構造的差異はもつもののAゲノム群に属することも知られている。したがって, 当雑種にみられる3価形成は, 主に, aclからのAAとdmsからのA^dの3ゲノム間の染色体対合に由来すると推論でき, 両種はこれらのゲノムの相同性によって相互に関係づけられているものと考えられる。 / Meiotic behavior and fertility were studied in a heptaploid F_1 hybrid (2n=84) obtained from crossing S. acaule (acl, 2n=48) with S. demissum (dms, 2n=72), with the aim of assessing a genomic relationship between the parent species. Crossability between the two species was very low, the number of hybrid plants per pollination being only 0.02. Morphological evidence indicated that the hybrid arose through the union of an unreduced egg of acl and a reduced pollen grain of dms. The hybrid had the mean pairing frequency of (0.18)_V+(1.11)_+(11.73)_+(18.11)_+(7.26)_I per cell at metaphase I, with (12)_+(20)_+8_I as the modal configuration. Its subsequent behaviors were extremely irregular, showing several laggards in all the cells and chromatid bridges in occasional cells at anaphase I and also scattered chromosomes in 94% of the cells at metaphase II. The hybrid gave only 27% stainable pollen and no seed either on selfing or on backcrossing with both parents. The pattern of chromosome pairing found in the hybrid was interpreted in terms of genomic relationship between both parent species. From this, it was suggested that one (A) of the two genomes (designated AA^a) which acl possess in its gametes seems to be closely similar to, but not identical with, one (A^d) of the three genomes (A^dC_1C_2) which dms possess in its gemetes