Atherosclerotic renovascular disease: beyond the renal artery stenosis.
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Atherosclerosis↗
Biomedical subjects
Pascal Meier
Publications and source records attributed to Pascal Meier.
Oxidized low-density lipoproteins activate CD4+ T cell apoptosis in patients with end-stage renal disease through Fas engagement.
Oxidized LDL (oxLDL) are cytotoxic to vascular cells, but their possible toxic action on T cells from patients with ESRD has not been evaluated. oxLDL concentrations were measured and compared in patients who were on long-term hemodialysis (HD), in patients who had ESRD and were on continuous ambulatory peritoneal dialysis, in nondialyzed patients with chronic kidney disease, and in age- and gender-matched control subjects. In parallel, the proliferative capacity of CD69+/CD4+ T cells and their rate of apoptosis, IL-2 expression, and intracellular expression of Bcl-2 and Bax were determined in vitro. The oxLDL concentrations were significantly higher in HD patients (all P = 0.001). Upon phytohemagglutinin stimulation, CD69+/CD4+ T cells from HD patients proliferated significantly less than those from the other patients' group (both P < 0.001). oxLDL but not the native LDL were led to CD69+/CD4+ T cells' program cell death in a dosage- and time-dependent manner through Fas pathway (P = 0.001). Cell surface Fas expression was followed by DNA fragmentation when CD69+/CD4+ T cells from HD patients or control subjects were cultured with oxLDL (200 microg/ml; 31 +/- 3 versus 25 +/- 3%; P = 0.001). In the presence of oxLDL, CD69+/CD4+ T cells from HD patients expressed significantly lower IL-2 levels, which strongly correlated with a decrease in the antiapoptotic Bcl-2 and conversely with an increase in the proapoptotic Bax expression. In conclusion, these data suggest that, in HD patients, exposure of activated CD4+ T cells to oxLDL leads to Fas-mediated apoptosis in association with inhibition of IL-2 expression. Subsequently, this may favor activation of mitochondria-dependent apoptotic pathways, leading to activated CD4+ T cell dysfunction.
Antigens, CD↗
Coronary collateral function long after drug-eluting stent implantation.
OBJECTIVES: This study was designed to compare coronary collateral function in patients after bare-metal stent (BMS) or drug-eluting stent (DES) implantation. BACKGROUND: Drug-eluting stents have an inhibitory effect on the production of cytokines, chemotactic proteins, and growth factors, and may therefore negatively affect coronary collateral growth. METHODS: A total of 120 patients with long-term stable coronary artery disease (CAD) after stent implantation were included. Both the BMS group and the DES group comprised 60 patients matched for in-stent stenosis severity of the vessel undergoing collateral flow index (CFI) measurement at follow-up and for the duration of follow-up. The primary end point of the investigation was invasively determined coronary collateral function 6 months after stent implantation. Collateral function was assessed by simultaneous aortic, coronary wedge, and central venous pressure measurements (yielding CFI) and by intracoronary electrocardiogram during balloon occlusion. RESULTS: There were no differences between the groups regarding age, gender, body mass index, frequency of cardiovascular risk factors, use of cardiovascular drugs, severity of CAD, or site of coronary artery stenoses. Despite equal in-stent stenosis severity (46 +/- 34% and 45 +/- 36%) and equal follow-up duration (6.2 +/- 10 months and 6.5 +/- 5.4 months), CFI was diminished in the DES versus BMS group (0.154 +/- 0.097 vs. 0.224 +/- 0.142; p = 0.0049), and the rate of collaterals insufficient to prevent ischemia during occlusion (intracoronary electrocardiographic ST-segment elevation > or =0.1 mV) was higher with 50 of 60 patients in the DES group and 33 of 60 patients in the BMS group (p = 0.001). CONCLUSIONS: Collateral function long after coronary stenting is impaired with DES (sirolimus and paclitaxel) when compared with BMS. Considering the protective nature of collateral vessels, this could lead to more serious cardiac events in the presence of an abrupt coronary occlusion.
Aged↗
Rethinking the triggering inflammatory processes of chronic periaortitis.
Chronic periaortitis (CP) is an uncommon inflammatory disease which primarily involves the infrarenal portion of the abdominal aorta. However, CP should be regarded as a generalized disease with three different pathophysiological entities, namely idiopathic retroperitoneal fibrosis (RPF), inflammatory abdominal aortic aneurysm and perianeurysmal RPF. These entities share similar histopathological characteristics and finally will lead to fibrosis of the retroperitoneal space. Beside fibrosis, an infiltrate with variable chronic inflammatory cell is present. The majority of these cells are lymphocytes and macrophages as well as vascular endothelial cells, most of which are HLA-DR-positive. B and T cells are present with a majority of T cells of the T-helper phenotype. Cytokine gene expression analysis shows the presence of interleukin (IL)-1alpha, IL-2, IL-4, interferon-gamma and IL-2 receptors. Adhesion molecules such as E-selectin, intercellular adhesion molecule-1 and the vascular cell adhesion molecule-1 were also found in aortic tissue, and may play a significant role in CP pathophysiology. Although CP pathogenesis remains unknown, an exaggerated inflammatory response to advanced atherosclerosis (ATS) has been postulated to be the main process. Autoimmunity has also been proposed as a contributing factor based on immunohistochemical studies. The suspected allergen may be a component of ceroid, which is elaborated within the atheroma. We review the pathogenesis and the pathophysiology of CP, and its potential links with ATS. Clinically relevant issues are summarized in each section with regard to the current working hypothesis of this complex inflammatory disease.
Aortic Aneurysm, Abdominal↗
The Drosophila inhibitor of apoptosis protein DIAP2 functions in innate immunity and is essential to resist gram-negative bacterial infection.
The founding member of the inhibitor of apoptosis protein (IAP) family was originally identified as a cell death inhibitor. However, recent evidence suggests that IAPs are multifunctional signaling devices that influence diverse biological processes. To investigate the in vivo function of Drosophila melanogaster IAP2, we have generated diap2 null alleles. diap2 mutant animals develop normally and are fully viable, suggesting that diap2 is dispensable for proper development. However, these animals were acutely sensitive to infection by gram-negative bacteria. In Drosophila, infection by gram-negative bacteria triggers the innate immune response by activating the immune deficiency (imd) signaling cascade, a NF-kappaB-dependent pathway that shares striking similarities with the pathway of mammalian tumor necrosis factor receptor 1 (TNFR1). diap2 mutant flies failed to activate NF-kappaB-mediated expression of antibacterial peptide genes and, consequently, rapidly succumbed to bacterial infection. Our genetic epistasis analysis places diap2 downstream of or in parallel to imd, Dredd, Tak1, and Relish. Therefore, DIAP2 functions in the host immune response to gram-negative bacteria. In contrast, we find that the Drosophila TNFR-associated factor (Traf) family member Traf2 is dispensable in resistance to gram-negative bacterial infection. Taken together, our genetic data identify DIAP2 as an essential component of the Imd signaling cascade, protecting the organism from infiltrating microbes.
Animals↗
The relative myocardial blood volume differentiates between hypertensive heart disease and athlete's heart in humans.
AIMS: The adaptation of the myocardial microcirculation in humans to pathologic and physiologic stress has not been examined in vivo so far. We sought to test whether the relative blood volume (rBV) measured by myocardial contrast echocardiography (MCE) can differentiate between left ventricular (LV) hypertrophy (LVH) in hypertensive heart disease and athlete's heart. METHODS AND RESULTS: Four groups were investigated: hypertensive patients with LVH (n = 15), semi-professional triathletes with LVH (n = 15), professional football players (n = 15), and sedentary control individuals without cardiovascular disease (n = 15). MCE was performed at rest and during adenosine-induced hyperaemia. The rBV (mL mL(-1)), its exchange frequency (beta, min(-1)), and myocardial blood flow (mL min(-1) g(-1)) were derived from steady state and refill sequences of ultrasound contrast agent. Hypertensive patients had lower rBV (0.093 +/- 0.013 mL mL(-1)) than triathletes (0.141 +/- 0.012 mL mL(-1), P < 0.001), football players (0.129 +/- 0.014 mL mL(-1), P < 0.001), and sedentary individuals (0.126 +/- 0.018 mL mL(-1), P < 0.001). Conversely, the exchange frequency (beta) was significantly higher in hypertensive patients (11.3 +/- 3.8 min(-1)) than in triathletes (7.4 +/- 1.8 min(-1)), football players (7.7 +/- 2.3 min(-1)), and sedentary individuals (9.0+/-2.5 min(-1)). An rBV below 0.114 mL mL(-1) distinguished hypertensive patients and triathletes with a sensitivity of 93% and a specificity of 100%. CONCLUSION: Pathologic and physiologic LVH were differentiated non-invasively and accurately by rBV, a measure of vascularisation assessed by MCE.
Adult↗
Variable ECG signs of ischemia during controlled occlusion of the left and right coronary artery in humans.
Infarct size (IS) increases with vascular occlusion time, area at risk for infarction, lack of collateral supply, absence of preconditioning, and myocardial demand for O2 supply. ECG S-T segment elevation is used as a measure of severity of ischemia and a surrogate for IS. This study in 50 patients with coronary artery disease undergoing a first 120-s balloon occlusion of a stenosis sought to determine whether S-T segment elevation, corrected for the above-mentioned variables, in the left coronary artery (LCA group, n = 36) is different from that in the right coronary artery (RCA group, n = 14) territory. After consideration of all known determinants of IS, particularly mass at risk and collateral supply, the LCA territory is more sensitive than the RCA region to a 2-min period of myocardial ischemia.
Coronary Artery Disease↗
Safety and efficacy of subcutaneous-only granulocyte-macrophage colony-stimulating factor for collateral growth promotion in patients with coronary artery disease.
OBJECTIVES: This study was designed to investigate the safety and efficacy of a short-term subcutaneous-only granulocyte-macrophage colony-stimulating factor (GM-CSF) protocol for coronary collateral growth promotion. BACKGROUND: The safety and efficacy of an exclusively systemic application of GM-CSF in patients with coronary artery disease (CAD) and collateral artery promotion has not been studied so far. METHODS: In 14 men (age 61 +/- 11 years) with chronic stable CAD, the effect of GM-CSF (molgramostim) on quantitatively assessed collateral flow was tested in a randomized, double-blind, placebo-controlled fashion. The study protocol consisted of an invasive collateral flow index (CFI) measurement in a stenotic as well as a normal coronary artery before and after a two-week period with subcutaneous GM-CSF (10 microg/kg; n = 7) or placebo (n = 7). Collateral flow index was determined by simultaneous measurement of mean aortic, distal coronary occlusive, and central venous pressure. RESULTS: Collateral flow index in all vessels changed from 0.116 +/- 0.05 to 0.159 +/- 0.07 in the GM-CSF group (p = 0.028) and from 0.166 +/- 0.06 to 0.166 +/- 0.04 in the placebo group (p = NS). The treatment-induced difference in CFI was +0.042 +/- 0.05 in the GM-CSF group and -0.001 +/- 0.04 in the placebo group (p = 0.035). Among 11 determined cytokines, chemokines, and their monocytic receptor concentrations, the treatment-induced change in CFI was predicted by the respective change in tumor necrosis factor-alpha concentration. Two of seven patients in the GM-CSF group and none in the placebo group suffered an acute coronary syndrome during the treatment period. CONCLUSIONS: A subcutaneous-only, short-term protocol of GM-CSF is effective in promoting coronary collateral artery growth among patients with CAD. However, the drug's safety regarding the occurrence of acute coronary syndrome is questionable.
Aged↗
Locally targeted cytoprotection with dextran sulfate attenuates experimental porcine myocardial ischaemia/reperfusion injury.
AIMS: Intravascular inflammatory events during ischaemia/reperfusion injury following coronary angioplasty alter and denudate the endothelium of its natural anticoagulant heparan sulfate proteoglycan (HSPG) layer, contributing to myocardial tissue damage. We propose that locally targeted cytoprotection of ischaemic myocardium with the glycosaminoglycan analogue dextran sulfate (DXS, MW 5000) may protect damaged tissue from reperfusion injury by functional restoration of HSPG. METHODS AND RESULTS: In a closed chest porcine model of acute myocardial ischaemia/reperfusion injury (60 min ischaemia, 120 min reperfusion), DXS was administered intracoronarily into the area at risk 5 min prior to reperfusion. Despite similar areas at risk in both groups (39+/-8% and 42+/-9% of left ventricular mass), DXS significantly decreased myocardial infarct size from 61+/-12% of the area at risk for vehicle controls to 39+/-14%. Cardioprotection correlated with reduced cardiac enzyme release creatine kinase (CK-MB, troponin-I). DXS abrogated myocardial complement deposition and substantially decreased vascular expression of pro-coagulant tissue factor in ischaemic myocardium. DXS binding, detected using fluorescein-labelled agent, localized to ischaemically damaged blood vessels/myocardium and correlated with reduced vascular staining of HSPG. CONCLUSION: The significant cardioprotection obtained through targeted cytoprotection of ischaemic tissue prior to reperfusion in this model of acute myocardial infarction suggests a possible role for the local modulation of vascular inflammation by glycosaminoglycan analogues as a novel therapy to reduce reperfusion injury.
Animals↗
The quantification of absolute myocardial perfusion in humans by contrast echocardiography: algorithm and validation.
OBJECTIVES: We sought to test whether myocardial blood flow (MBF) can be quantified by myocardial contrast echocardiography (MCE) using a volumetric model of ultrasound contrast agent (UCA) kinetics for the description of refill curves after ultrasound-induced microsphere destruction. BACKGROUND: Absolute myocardial perfusion or MBF (ml.min(-1).g(-1)) is the gold standard to assess myocardial blood supply, and so far it could not be obtained by ultrasound. METHODS: The volumetric model yielded MBF = rBV.beta/rho(T), where rho(T) equals tissue density. The relative myocardial blood volume rBV and its exchange frequency beta were derived from UCA refill sequences. Healthy volunteers underwent MCE and positron emission tomography (PET) at rest (group I: n = 15; group II: n = 5) and during adenosine-induced hyperemia (group II). Fifteen patients with coronary artery disease underwent simultaneous MCE and intracoronary Doppler measurements before and during intracoronary adenosine injection. RESULTS: In vitro experiments confirmed the volumetric model and the reliable determination of rBV and beta for physiologic flow velocities. In group I, 187 of 240 segments were analyzable by MCE, and a linear relation was found between MCE and PET perfusion data (y = 0.899x + 0.079; r(2) = 0.88). In group II, resting and hyperemic perfusion data showed good agreement between MCE and PET (y = 1.011x + 0.124; r(2) = 0.92). In patients, coronary stenosis varied between 0% to 89%, and myocardial perfusion reserve was in good agreement with coronary flow velocity reserve (y = 0.92x + 0.14; r(2) = 0.73). CONCLUSIONS: The volumetric model of UCA kinetics allows the quantification of MBF in humans using MCE and provides the basis for the noninvasive and quantitative assessment of coronary artery disease.
Adenosine↗
The future of angiotensin II inhibition in cardiovascular medicine.
Drugs, which interfere with the renin-angiotensin-aldosterone cascade such as angiotensin converting enzyme (ACE) inhibitors, have been available to clinicians for more than 20 years. They are now recognized as a very effective approach to treat patients with hypertension, heart failure, diabetic and non-diabetic chronic renal failure or patients with a high cardiovascular risk. The recent development of angiotensin II (Ang II) receptor antagonist has enabled to improve significantly the tolerability profile of this group of drugs while maintaining a high clinical efficacy. Yet, with the availability of Ang II receptor antagonists, new questions have arisen. Is it still possible to gain in efficacy with newer agents? What is the future of drugs such as neutral endopeptidase (NEP)/ACE inhibitors or renin inhibitors? The first objective of this review is to discuss the clinical implications of several large clinical trials that have been published recently with ACE inhibitors and Ang II receptor antagonists such as ALLHAT, LIFE, OPTIMAAL, Val-Heft, SCOPE, and more recently, CHARM, VALIANT and VALUE. With these trials, we can now define more precisely the role of these blockers of the renin-angiotensin system in the management of patients with cardiovascular complications. The second part of this review is devoted to new drugs interfering with the renin-angiotensin system. We discuss the recent results obtained with NEP/ACE inhibitors also named vasopeptidase inhibitors. Several compounds were or are in development but the experience with omapatrilat has blunted the enthusiasms for these compounds. Yet, vasopeptidase inhibitors remain very effective antihypertensive drugs and there is a great therapeutic potential for these agents provided one can define more accurately the risk/benefit ratio and the clinical indications. Finally, we present the recent data obtained with SPP 100, a new renin inhibitor that is actually under clinical development. SPP 100 has a sufficient bioavailability to induce a sustained blockade of the renin-angiotensin system when given orally to normal subjects. Recent studies have shown that SPP 100 lowers blood pressure in hypertensive patients as effectively as an Ang II receptor antagonist.
Angiotensin II↗
IAPs are functionally non-equivalent and regulate effector caspases through distinct mechanisms.
Some members of the inhibitor of apoptosis (IAP) family suppress apoptosis by neutralizing caspases. The current model suggests that all caspase-regulatory IAPs function as direct enzyme inhibitors, blocking effector caspases by binding to their catalytically active pockets. Here we show that IAPs are functionally non-equivalent and regulate effector caspases through distinct mechanisms. Whereas XIAP binds directly to the active-site pockets of effector caspases, we find that regulation of effector caspases by Drosophila IAP1 (DIAP1) requires an evolutionarily conserved IAP-binding motif (IBM) at the neo-amino terminus of the large caspase subunit. Remarkably, unlike XIAP, DIAP1-sequestered effector caspases remain catalytically active, suggesting that DIAP1 does not function as a bona fide enzyme inhibitor. Moreover, we demonstrate that the mammalian IAP c-IAP1 interacts with caspase-7 in an exclusively IBM-dependent, but active site pocket-independent, manner that is mechanistically similar to DIAP1. The importance of IBM-mediated regulation of effector-caspases in vivo is substantiated by the enhanced apoptotic potency of IBM-mutant versions of drICE, DCP-1 and caspase-7.
Amino Acid Motifs↗
IAP-antagonists exhibit non-redundant modes of action through differential DIAP1 binding.
The Drosophila inhibitor of apoptosis protein DIAP1 ensures cell viability by directly inhibiting caspases. In cells destined to die this IAP-mediated inhibition of caspases is overcome by IAP-antagonists. Genetic evidence indicates that IAP-antagonists are non-equivalent and function synergistically to promote apoptosis. Here we provide biochemical evidence for the non-equivalent mode of action of Reaper, Grim, Hid and Jafrac2. We find that these IAP-antagonists display differential and selective binding to specific DIAP1 BIR domains. Consistently, we show that each DIAP1 BIR region associates with distinct caspases. The differential DIAP1 BIR interaction seen both between initiator and effector caspases and within IAP-antagonist family members suggests that different IAP-antagonists inhibit distinct caspases from interacting with DIAP1. Surprisingly, we also find that the caspase-binding residues of XIAP predicted to be strictly conserved in caspase-binding IAPs, are absent in DIAP1. In contrast to XIAP, residues C-terminal to the DIAP1 BIR1 domain are indispensable for caspase association. Our studies on DIAP1 and caspases expose significant differences between DIAP1 and XIAP suggesting that DIAP1 and XIAP inhibit caspases in different ways.
Animals↗
Imaging medullary cystic kidney disease with magnetic resonance.
Medullary cystic kidney disease is characterized by multiple renal cysts at the corticomedullary boundary area, by autosomal dominant inheritance, and by onset of chronic renal failure in the third decade of life. Its clinical manifestations are often insignificant and nonspecific. Furthermore, its diagnosis may be difficult in sporadic forms where genetic linkage analysis cannot be performed. The authors report the case of a patient presenting with a sporadic form of medullary cystic kidney disease whose diagnosis was confirmed using computerized tomography with 3-dimensional reconstruction at the nephrography-excretion time and magnetic resonance imaging (MRI) with magnetic resonance angiography and urography after the injection of gadolinium, a nonnephrotoxic compound. Both imaging techniques showed normal-sized, normal-shaped kidneys containing multiple cysts from 1 to 30 mm in diameter in the medulla and at the corticomedullary junction. A characteristic medullary nephrogram appeared after injection of iodinated contrast medium or gadolinium corresponding to contrast-filled dilated collecting ducts. This report shows that MRI with gadolinium injection can substitute for computerized tomography in azotemic patients. MRI seems particularly promising for the diagnosis of cystic diseases of the kidney and must also be considered when investigating a patient with chronic renal failure of unknown origin.
Adult↗
Are cyclooxygenase-2-selective inhibitors safe for the kidneys?
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Animals↗
Programmed cell death: Superman meets Dr Death.
This year's Cold Spring Harbor meeting on programmed cell death (September 17-21, 2003), organised by Craig Thompson and Junying Yuan, was proof that the 'golden age' of research in this field is far from over. There was a flurry of fascinating insights into the regulation of diverse apoptotic pathways and unexpected non-apoptotic roles for some of the key apoptotic regulators and effectors. In addition to their role in cell death, components of the apoptotic molecular machinery are now known to also function in a variety of essential cellular processes, such as regulating glucose homeostasis, lipid metabolism, cell proliferation and differentiation.
Animals↗
Degradation of DIAP1 by the N-end rule pathway is essential for regulating apoptosis.
Some members of the inhibitor of apoptosis (IAP) protein family block apoptosis by binding to and neutralizing active caspases. We recently demonstrated that a physical association between IAP and caspases alone is insufficient to regulate caspases in vivo and that an additional level of control is provided by IAP-mediated ubiquitination of both itself and the associated caspases. Here we show that Drosophila IAP 1 (DIAP1) is degraded by the 'N-end rule' pathway and that this process is indispensable for regulating apoptosis. Caspase-mediated cleavage of DIAP1 at position 20 converts the more stable pro-N-degron of DIAP1 into the highly unstable, Asn-bearing, DIAP1 N-degron of the N-end rule degradation pathway. Thus, DIAP1 represents the first known metazoan substrate of the N-end rule pathway that is targeted for degradation through its amino-terminal Asn residue. We demonstrate that the N-end rule pathway is required for regulation of apoptosis induced by Reaper and Hid expression in the Drosophila melanogaster eye. Our data suggest that DIAP1 instability, mediated through caspase activity and subsequent exposure of the N-end rule pathway, is essential for suppression of apoptosis. We suggest that DIAP1 safeguards cell viability through the coordinated mutual destruction of itself and associated active caspases.
Amino Acid Sequence↗
Plasma level of soluble Fas is an independent marker of cardiovascular disease in ESRD patients.
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Biomarkers↗