Summs~The role of nitric oxide in the immune response to allogeneic tissue was explored in an in vivo cardiac transplant model in the rat. Nitric oxide production during organ rejection was demonstrated by elevations in systemic serum nitrite/nitrate levels and by electron paramagnetic resonance spectroscopy. Messenger RNA for the inducible nitric oxide synthase enzyme was detected in the rejecting aUografted heart, but not in the nonrejecting isografted heart. The enzyme was demonstrated to be biologically active by the in vitro conversion of t-arginine to t-dtrulline and was immunohistochemically localized to the infiltrating inflammatory cells. Treatment with aminoguanidine, a preferential inhibitor of the inducible nitric oxide synthase isoform, prevented the increased nitric oxide production in the transplanted organ and significantly attenuated the pathogenesis of acute rejection. Aminoguanidine treatment prolonged graft survival, improved graft contractile function, and significantly reduced the histologic grade of rejection. These results suggest an important role for nitric oxide in mediating the immune response to allogeneic tissue. Inhibition of inducible nitric oxide synthase may provide a novel therapeutic modality in the management of acute transplant rejection and of other immune-mediated processes. cute rejection is mediated by humoral and cellular immune mechanisms, and is characterized by an intense inflammatory cell infiltrate and progressive destruction of the grafted organ. Despite many recent advances in the understanding of the immune system, the regulatory and effector mechanisms underlying the rejection process remain incompletely understood. Recent reports have demonstrated production of the free radical nitric oxide (NO) 1 during organ transplant rejection (1, 2). NO is synthesized from the amino acid t-arginine by a family of enzymes, the nitric oxide syn-

The present study was designed to further the characterization of age- related changes in the deformability of human erythrocytes. The top (approximately young) and bottom (approximately old) 10% fractions of density-separated red cells from ten normal donors were subjected to graded levels of shear stress in a rheoscope. Measurements were made of steady-state elongation (cells tank treading in a state of dynamic equilibrium) and the time course of shape recovery following abrupt cessation of shear. In parallel with the rheologic experiments, several physical and chemical properties were assayed to determine correlates of mechanical properties. These included mean cell volume, mean corpuscular hemoglobin concentration, type A1 hemoglobin, glucosylation of membrane proteins, and membrane phospholipid and protein concentration. The microrheologic observations revealed that only about 90% of the old cells retained their capacity to tank tread. However, the tank-treading cells elongated less than their younger counterparts at corresponding levels of shear stress, thus demonstrating a reduced level of deformability. Further analysis of the data indicates that increases in membrane viscosity and elastic modulus along with a significant loss in excess surface area contribute to the limitation of the ability of the older cells to change shape.

In discussions of vascular complications of diabetes the fact that capillary basement membranes are, in general, thickened (CBMT) in poorly controlled diabetics is no longer at issue. However, three important questions concerning the pathophysiologic significance of CBMT remain unanswered: (1) How and why do capillary basement membranes thicken in diabetes? (2) What is the functional significance of capillary basement membrane changes in diabetes? (3) What is the nature of the relationship of CBMT to other forms of diabetic vascular disease; in particular, is CBMT observed in tissues amenable to needle biopsy, i.e., skeletal muscle, useful in identifying individuals at high risk for developing clinically significant retinopathy, nephropathy, or atherosclerotic vascular disease? In this survey, we will consider the nature of capillary basement membrane changes in diabetes and subsequently address the above questions.

This study was undertaken to examine the influence of temperature on physical properties of red cell membranes. Red cells adhering to cover slips were subjected to fluid shear stress in a rotating disc apparatus for 1 min or for 10 min at temperatures ranging from 2 degrees to 50 degress C. They were fixed while subject to shear stress by addition of glutaraldehyde and then processed for examination and photography by reflected-light microscopy. Cell dimensions were obtained with a computerized planimeter. At shear stresses under 2 dynes/sq cm, cells changed shape from biconcave discs to tear drops, the dimensions of which were influenced very little by temperature or duration of shear stress. Above 2 dynes/sq cm, filamentous processes or “tethers” developed at attachment points of cells to cover slips. Tether length and the percentage of cells possessing tethers increased markedly with increasing temperature and duration of shear stress. At approximately 48 degrees C, a dramatic change occurred over a narrow temperature range such that cells were markedly elongated and irregularly deformed by a shear stress of 1 dyne/sq cm or less. These observations demonstrate that elongation of human red cells subjected to fluid shear stress in a rotating disc system is markedly influenced by temperature as well as by magnitude and duration of shear stress. They also indicate that significant increases in red cell membrane fluidity occur between 2 degrees and 24 degrees-37 degrees C and again between 48 degrees and 50 degrees C.

Background: microRNAs (miRNA, miR) are thought to interact with multiple mRNAs resulting in either translational repression or degradation which is involved in the EMT process. Since miRNAs distributed with tissue specificity, the role of miRNAs in peritoneal fibrosis remains unknown. Our unpressed data showed that expression of miRNA589 was notably decreased in HPMCs isolated from patients undergoing long-term continuous ambulatory peritoneal dialysis (CAPD).Objective: To determine if miRNA589 regulates the EMT induced by TGFβ1 in human peritoneal mesothelial cell line (HMrSV5 cells).Methods: HMrSV5 cells were divided into three groups: control group (only FBS-free DMEM/F12), TGF-β1 group (treated with TGF-1 5 ng/ml for 24h) and pre-miR-5891 group (pre-treated with pre-miR-589 to up-regulate the level of miR-589, and treated with TGF-1 5 ng/ml for 24h). The level of miRNA589 was determined by realtime PCR. The expressions of ZO-1, vimentin, E-cadherinin HPMCs were determined by immunofluorescence, realtime PCR, and Western blot, respectively.Result: In vitro,TGF1 led to up-regulation of vimentin and downregulation of ZO-1 as well as E-cadherin in HMrSV5 cells, which suggested EMT was induced. The changes were accompanied with notably decreased level of miRNA589 in HMrSV5 cells treated by TGF1. Over-expression of miRNA589 by transfection with pre-miRNA589 partially reversed these EMT changes.Conclusion: miRNA589 mediates TGF1-induced EMT in human peritoneal mesothelial cells. cArdiovAsculAr comPlicAtions Valvular Calcifications and Associated FactorsBackground: The presence of vascular and valvular calcification is considered a risk factor in cardiovascular disease among patients in peritoneal dialysis (PD). Nevertheless, there is not sufficient information available to permit relating valvular calcification (VC) with clinical variables and biochemical markers. Our aim was to know the association of valvular calcification with clinical variables and biochemical markers in patients on PD.Methods and Material: We did a cross-sectional study in 97 PD patients, demographic and clinical data were recorded; echocardiography was performed to detect VC in mitral anular and aortic valves, as well as measuring serum albumin, phosphorus, calcium, cholesterol and hs-CRP, (immunoturbidimetric assay) and fetuin-A (EDI ELISA) The continuous variables are expressed as means ±SD; or median (range), differences among groups were analyzed with Student t and x 2 .Results: The mean age was 48 ±12 years old, time on dialysis was 12±2 months, with diabetic nephropathy as a cause of disease, 54%, male72%, BMI of 25± 4 kg/m 2 ,. 53% had diabetes and 50% smokers. Fetuin levels were 0.33±0.1 g/L, cholesterol 187±45 mg/dL, total calcium 8.9±0.7 mg/dL, phosphorus 5.3±1.7 mg/dL, albumin 3.7±0.4 g/dL. The patients with VC were 42%, of which mitral was 36%, aortic 49%, and both 15%. No significant differences were presented in presence of diabetes, smokers, gender, calcitriol treatment and age regarding calcified patients vs. noncalcified; ho...