Jan H.M. Tordoir

In the present study, we examined the expression of regulators of bone formation and osteoclastogenesis in human atherosclerosis because accumulating evidence suggests that atherosclerotic calcification shares features with bone calcification. The most striking finding of this study was the constitutive immunoreactivity of matrix Gla protein, osteocalcin, and bone sialoprotein in nondiseased aortas and the absence of bone morphogenetic protein (BMP)-2, BMP-4, osteopontin, and osteonectin in nondiseased aortas and early atherosclerotic lesions. When atherosclerotic plaques demonstrated calcification or bone formation, BMP-2, BMP-4, osteopontin, and osteonectin were upregulated. Interestingly, this upregulation was associated with a sustained immunoreactivity of matrix Gla protein, osteocalcin, and bone sialoprotein. The 2 modulators of osteoclastogenesis (osteoprotegerin [OPG] and its ligand, OPGL) were present in the nondiseased vessel wall and in early atherosclerotic lesions. In advanced calcified lesions, OPG was present in bone structures, whereas OPGL was only present in the extracellular matrix surrounding calcium deposits. The observed expression patterns suggest a tight regulation of the expression of bone matrix regulatory proteins during human atherogenesis. The expression pattern of both OPG and OPGL during atherogenesis might suggest a regulatory role of these proteins not only in osteoclastogenesis but also in atherosclerotic calcification.

Accelerated intimal and medial calcification and sclerosis accompany the increased cardiovascular mortality of dialysis patients, but the pathomechanisms initiating microcalcifications of the media are largely unknown. In this study, we systematically investigated the ultrastructural properties of medial calcifications from patients with uremia. We collected iliac artery segments from 30 dialysis patients before kidney transplantation and studied them by radiography, microcomputed tomography, light microscopy, and transmission electron microscopy including electron energy loss spectrometry, energy dispersive spectroscopy, and electron diffraction. In addition, we performed synchrotron x-ray analyses and immunogold labeling to detect inhibitors of calcification. Von Kossa staining revealed calcification of 53% of the arteries. The diameter of these microcalcifications ranged from 20 to 500 nm, with a core-shell structure consisting of up to three layers (subshells). Many of the calcifications consisted of 2- to 10-nm nanocrystals and showed a hydroxyapatite and whitlockite crystalline structure and mineral phase. Immunogold labeling of calcification foci revealed the calcification inhibitors fetuin-A, osteopontin, and matrix gla protein. These observations suggest that uremic microcalcifications originate from nanocrystals, are chemically diverse, and intimately associate with proteinaceous inhibitors of calcification. Furthermore, considering the core-shell structure of the calcifications, apoptotic bodies or matrix vesicles may serve as a calcification nidus.

IntroductionBackground.Left ventricular hypertrophy is common in renal transplant patients.One of the factors that Left ventricular hypertrophy (LVH ) is very common might contribute to this phenomenon is the persisting in patients with end-stage renal failure.This is especipresence of an arteriovenous (AV ) fistula.Several ally important in view of the relationship between reports have described the presence of high-output LVH and mortality in these patients.The cause of cardiac failure, which subsided after closure of the AV LVH in renal patients is multifactorial and includes fistula.However, the long-term effects of elective closfactors such as hypertension, anaemia, the uraemic ure of the AV fistula on left ventricular dimensions state itself, and the presence of an arteriovenous fistula in stable renal transplant patients have never been (AV ) [1].It has been shown that left ventricular prospectively studied.dimensions may improve after renal transplantation, Subjects and methods.Twenty patients (15 male, 5 although complete regression of LVH is usually not female; mean age 5112 years) with a well-functioning obtained [2][3][4].One of the factors that may contribute renal transplant were included.Patients with severe to the persistence of LVH after renal transplantation heart failure (NYHA III or IV ) were excluded.Before is the presence of an AV fistula.The presence of an and 3-4 months after closure of the AV fistula, an AV fistula lowers systemic vascular resistance, resulting echocardiogram was performed.Fistula flow was in an increase in stroke volume and cardiac output in assessed by colour duplex-Doppler sonography.order to maintain blood pressure [5].In the end, this Results.Mean fistula flow was 1790648 ml/min.may lead to left ventricular volume overload and After closure of the fistula, left ventricular end-diastolic eccentric LVH.Various case reports have described diameter (LVEDD) (51.55.8 vs 49.35.4mm, high-output cardiac failure in patients with high-flow P<0.01) and left ventricular mass index (LVMi) fistulae, which subsided after closure of the fistula (135.034.1 vs 119.823.2) decreased.The change in [6,7].However, the cardiac effects of closure of AV LVMi after fistula closing was significantly related to fistulae in patients without clinical heart failure have the LVMi and LVEDD before operation (r=0.74 until now not been studied systematically.In this study and r=0.60,P<0.01), but not to fistula flow.we prospectively assessed the effect of closure of an Interventricular septal and posterior-wall diastolic AV fistula on left ventricular dimensions in stable renal thickness did not change.Heart rate decreased (7210 transplant patients.vs 699, P=0.03) Blood pressure and creatinine clearance did not change. Conclusion.Closure of the arteriovenous fistula in Subjects and methods stable renal transplant patients results in a decrease in LVMi, due to a reduction in LVEDD.The change Patients in LVMi is significantly related to the LVMi and LVEDD before fistula closing.In patients with a well-After giving informed consent, 20 patients with a functioning functioning allograft and persistent LV dilatation, kidney transplant with stable renal function were included.closure of the AV fistula might be considered.Seventeen patients had a Cimino fistula, two patients a brachial fistula, and one patient a PTFE graft.Patient characteristics are summarized in Table 1.Patients with heart failure NYHA III or IV were excluded, because in these patients the progression of the cardiac disease might complicate the interpretation of the effect of fistula closing.

Although rupture of an atherosclerotic plaque is the major cause of acute vascular occlusion, the exact molecular mechanisms underlying this process are still poorly understood. In this study, we used suppression subtractive hybridization to make an inventory of genes that are differentially expressed in whole-mount human stable and ruptured plaques. Two libraries were generated, one containing 3000 clones upregulated and one containing 2000 clones downregulated in ruptured plaques. Macroarray analysis of 500 randomly chosen clones showed differential expression of 45 clones. Among the 25 clones that showed at least a 2-fold difference in expression was the gene of perilipin, upregulated in ruptured plaques, and the genes coding for fibronectin and immunoglobulin lambda chain, which were downregulated in ruptured plaques. Reverse transcriptase-polymerase chain reaction analysis on 10 individual ruptured and 10 individual stable plaques showed a striking consistency of expression for the clones SSH6, present in 8 ruptured and 2 stable plaques, and perilipin, expressed in 8 ruptured plaques and completely absent in stable plaques. Localization studies of both perilipin mRNA and protein revealed expression in cells surrounding the cholesterol clefts and in foam cells of ruptured atherosclerotic plaques. No expression was observed in nondiseased artery, and only a few cells in the shoulder region of stable plaques tested positive for perilipin. In conclusion, this study shows that it is possible to identify genes that are differentially expressed in whole-mount stable or ruptured atherosclerotic plaques. This approach may yield several potential regulators of plaque destabilization.

Increased understanding of the pathophysiology of ischemic acute kidney injury in renal transplantation may lead to novel therapies that improve early graft function. Therefore, we studied the renal microcirculation in ischemically injured kidneys from donors after cardiac death (DCD) and in living donor kidneys with minimal ischemia. During transplant surgery, peritubular capillaries were visualized by sidestream darkfield imaging. Despite a profound reduction in creatinine clearance, total renovascular resistance of DCD kidneys was similar to that of living donor kidneys. In contrast, renal microvascular perfusion in the early reperfusion period was 42% lower in DCD kidneys compared with living donor kidneys, which was accounted for by smaller blood vessel diameters in DCD kidneys. Furthermore, DCD kidneys were characterized by smaller red blood cell exclusion zones in peritubular capillaries and by greater production of syndecan-1 and heparan sulfate (main constituents of the endothelial glycocalyx) compared with living donor kidneys, providing strong evidence for glycocalyx degradation in these kidneys. We conclude that renal ischemia and reperfusion is associated with reduced capillary blood flow and loss of glycocalyx integrity. These findings form the basis for development of novel interventions to prevent ischemic acute kidney injury.