Amphetamines induce tissue factor and impair tissue factor pathway inhibitor: role of dopamine receptor type 4

Aims Amphetamine intake is associated with acute vascular syndromes. Since these events are caused by arterial thrombosis and this in turn is triggered by tissue factor (TF), this study examines whether amphetamines regulate TF in human endothelial cells. Methods and results Amphetamine (10−7-10−4 mol/L) enhanced thrombin- and tumour necrosis factor (TNF)-α-induced as well as basal TF expression (P = 0.029, 0.0003, and 0.003 at maximal concentration), and TNF-α-induced plasminogen activator inhibitor (PAI)-1 expression (P = 0.003), whereas tissue factor pathway inhibitor expression was impaired (P = 0.008). Similarly, 3,4-methylenedioxymethamphetamine (10−7-10−4 mol/L) enhanced TF expression (P = 0.046). These effects were paralleled by an increased TF activity (P = 0.002); moreover, clotting time of human plasma was accelerated by supernatant from amphetamine-treated cells (P = 0.03). Amphetamine enhanced TF mRNA expression via phosphorylation of the mitogen-activated protein kinases (MAPKs) extracellular signal-regulated kinase (ERK) and p38 (P = 0.03 and 0.033), but not c-Jun NH2-terminal kinase (JNK; P = 0.81). The effect of amphetamine on TF expression was abrogated by the dopamine D4 receptor antagonists L-745,870 and L-750,667, but not D2 or D3 receptor antagonists; furthermore, L-745,870 blunted the amphetamine-induced activation of ERK and p38, but not JNK. Conclusion Amphetamines induce endothelial TF expression via stimulation of dopamine D4 receptor and activation of the MAPKs p38 and ERK. These effects occur at clinically relevant amphetamine concentrations and may account for the increased incidence of acute vascular syndromes after amphetamine consumptio

PDGF-CC induces tissue factor expression: role of PDGF receptor α/β

Tissue factor (TF) is the principal trigger of the coagulation cascade and involved in arterial thrombus formation. Platelet-derived growth factor CC (PDGF-CC) is a recently discovered member of the PDGF family released upon platelet activation. This study assesses the impact of PDGF-CC on TF expression in human cells. PDGF-CC concentration-dependently induced TF expression by 2.5-fold in THP-1 cells, by 2.0-fold in human peripheral blood monocytes, by 1.4-fold in vascular smooth muscle cells, and by 2.6-fold in microvascular endothelial cells, but did not affect TF expression in aortic endothelial cells. A similar pattern was observed with PDGF-BB. In contrast, PDGF-AA did not alter TF expression in THP-1 cells. TF whole cell activity was induced following stimulation with PDGF-BB and PDGF-CC in THP-1 cells. Real-time polymerase chain reaction revealed that PDGF-CC induced TF mRNA. PDGF-CC transiently activated p42/44 MAP kinase [extracellular signal-regulated kinase (ERK)], while phosphorylation of the MAP kinases c-Jun NH2-terminal kinase (JNK) and p38 remained unaffected. PD98059, a specific inhibitor of ERK phosphorylation, but not the p38 inhibitor SB203580 or the JNK inhibitor SP600125 prevented PDGF-CC induced TF expression in a concentration-dependent manner. The effect of PDGF-CC was antagonized by both PDGF receptor α and PDGF receptor β neutralizing antibodies; in contrast, PDGF-BB was only inhibited by PDGF receptor β blocking antibody. PDGF receptor α and PDGF receptor β inhibition prevented PDGF-CC-induced ERK phosphorylation. PDGF-CC induces TF expression via activation of α/β receptor heterodimers and an ERK-dependent signal transduction pathwa

CT coronary angiography: impact of adapted statistical iterative reconstruction (ASIR) on coronary stenosis and plaque composition analysis

To assess the impact of adaptive statistical iterative reconstruction (ASIR) on coronary plaque volume and composition analysis as well as on stenosis quantification in high definition coronary computed tomography angiography (CCTA). We included 50 plaques in 29 consecutive patients who were referred for the assessment of known or suspected coronary artery disease (CAD) with contrast-enhanced CCTA on a 64-slice high definition CT scanner (Discovery HD 750, GE Healthcare). CCTA scans were reconstructed with standard filtered back projection (FBP) with no ASIR (0%) or with increasing contributions of ASIR, i.e. 20, 40, 60, 80 and 100% (no FBP). Plaque analysis (volume, components and stenosis degree) was performed using a previously validated automated software. Mean values for minimal diameter and minimal area as well as degree of stenosis did not change significantly using different ASIR reconstructions. There was virtually no impact of reconstruction algorithms on mean plaque volume or plaque composition (e.g. soft, intermediate and calcified component). However, with increasing ASIR contribution, the percentage of plaque volume component between 401 and 500 HU decreased significantly (p<0.05). Modern image reconstruction algorithms such as ASIR, which has been developed for noise reduction in latest high resolution CCTA scans, can be used reliably without interfering with the plaque analysis and stenosis severity assessmen

Image quality of low-dose CCTA in obese patients: impact of high-definition computed tomography and adaptive statistical iterative reconstruction

The accuracy of coronary computed tomography angiography (CCTA) in obese persons is compromised by increased image noise. We investigated CCTA image quality acquired on a high-definition 64-slice CT scanner using modern adaptive statistical iterative reconstruction (ASIR). Seventy overweight and obese patients (24 males; mean age 57years, mean body mass index 33kg/m2) were studied with clinically-indicated contrast enhanced CCTA. Thirty-five patients underwent a standard definition protocol with filtered backprojection reconstruction (SD-FBP) while 35 patients matched for gender, age, body mass index and coronary artery calcifications underwent a novel high definition protocol with ASIR (HD-ASIR). Segment by segment image quality was assessed using a four-point scale (1=excellent, 2=good, 3=moderate, 4=non-diagnostic) and revealed better scores for HD-ASIR compared to SD-FBP (1.5±0.43 vs. 1.8±0.48; p<0.05). The smallest detectable vessel diameter was also improved, 1.0±0.5mm for HD-ASIR as compared to 1.4±0.4mm for SD-FBP (p<0.001). Average vessel attenuation was higher for HD-ASIR (388.3±109.6 versus 350.6±90.3 Hounsfield Units, HU; p<0.05), while image noise, signal-to-noise ratio and contrast-to noise ratio did not differ significantly between reconstruction protocols (p=NS). The estimated effective radiation doses were similar, 2.3±0.1 and 2.5±0.1mSv (HD-ASIR vs. SD-ASIR respectively). Compared to a standard definition backprojection protocol (SD-FBP), a newer high definition scan protocol in combination with ASIR (HD-ASIR) incrementally improved image quality and visualization of distal coronary artery segments in overweight and obese individuals, without increasing image noise and radiation dos

Downstream resource utilization following hybrid cardiac imaging with an integrated cadmium-zinc-telluride/64-slice CT device

Purpose: Low yield of invasive coronary angiography and unnecessary coronary interventions have been identified as key cost drivers in cardiology for evaluation of coronary artery disease (CAD). This has fuelled the search for noninvasive techniques providing comprehensive functional and anatomical information on coronary lesions. We have evaluated the impact of implementation of a novel hybrid cadmium-zinc-telluride (CZT)/64-slice CT camera into the daily clinical routine on downstream resource utilization. Methods: Sixty-two patients with known or suspected CAD were referred for same-day single-session hybrid evaluation with CZT myocardial perfusion imaging (MPI) and coronary CT angiography (CCTA). Hybrid MPI/CCTA images from the integrated CZT/CT camera served for decision-making towards conservative versus invasive management. Based on the hybrid images patients were classified into those with and those without matched findings. Matched findings were defined as the combination of MPI defect with a stenosis by CCTA in the coronary artery subtending the respective territory. All patients with normal MPI and CCTA as well as those with isolated MPI or CCTA finding or combined but unmatched findings were categorized as "no match”. Results: All 23 patients with a matched finding underwent invasive coronary angiography and 21 (91%) were revascularized. Of the 39 patients with no match, 5 (13%, p < 0.001 vs matched) underwent catheterization and 3 (8%, p < 0.001 vs matched) were revascularized. Conclusion: Cardiac hybrid imaging in CAD evaluation has a profound impact on patient management and may contribute to optimal downstream resource utilizatio

Opportunistic deep learning powered calcium scoring in oncologic patients with very high coronary artery calcium (≥ 1000) undergoing 18F-FDG PET/CT

Our aim was to identify and quantify high coronary artery calcium (CAC) with deep learning (DL)-powered CAC scoring (CACS) in oncological patients with known very high CAC (≥ 1000) undergoing 18F-FDG-PET/CT for re-/staging. 100 patients were enrolled: 50 patients with Agatston scores ≥ 1000 (high CACS group), 50 patients with Agatston scores < 1000 (negative control group). All patients underwent oncological 18F-FDG-PET/CT and cardiac SPECT myocardial perfusion imaging (MPI) by 99mTc-tetrofosmin within 6 months. CACS was manually performed on dedicated non-contrast ECG-gated CT scans obtained from SPECT-MPI (reference standard). Additionally, CACS was performed fully automatically with a user-independent DL-CACS tool on non-contrast, free-breathing, non-gated CT scans from 18F-FDG-PET/CT examinations. Image quality and noise of CT scans was assessed. Agatston scores obtained by manual CACS and DL tool were compared. The high CACS group had Agatston scores of 2200 ± 1620 (reference standard) and 1300 ± 1011 (DL tool, average underestimation of 38.6 ± 26%) with an intraclass correlation of 0.714 (95% CI 0.546, 0.827). Sufficient image quality significantly improved the DL tool's capability of correctly assigning Agatston scores ≥ 1000 (p = 0.01). In the control group, the DL tool correctly assigned Agatston scores < 1000 in all cases. In conclusion, DL-based CACS performed on non-contrast free-breathing, non-gated CT scans from 18F-FDG-PET/CT examinations of patients with known very high (≥ 1000) CAC underestimates CAC load, but correctly assigns an Agatston scores ≥ 1000 in over 70% of cases, provided sufficient CT image quality. Subgroup analyses of the control group showed that the DL tool does not generate false-positives

First in vivo head-to-head comparison of high-definition versus standard-definition stent imaging with 64-slice computed tomography

The aim of this study was to compare image quality characteristics from 64-slice high definition (HDCT) versus 64-slice standard definition CT (SDCT) for coronary stent imaging. In twenty-five stents of 14 patients, undergoing contrast-enhanced CCTA both on 64-slice SDCT (LightSpeedVCT, GE Healthcare) and HDCT (Discovery HD750, GE Healthcare), radiation dose, contrast, noise and stent characteristics were assessed. Two blinded observers graded stent image quality (score 1=no, 2=mild, 3=moderate, and 4=severe artefacts). All scans were reconstructed with increasing contributions of adaptive statistical iterative reconstruction (ASIR) blending (0, 20, 40, 60, 80 and 100%). Image quality was significantly superior in HDCT versus SDCT (score 1.7±0.5 vs. 2.7±0.7; p<0.05). Image noise was significantly higher in HDCT compared to SDCT irrespective of ASIR contributions (p<0.05). Addition of 40% ASIR or more reduced image noise significantly in both HDCT and SDCT. In HDCT in-stent luminal attenuation was significantly lower and mean measured in-stent luminal diameter was significantly larger (1.2±0.4mm vs. 0.8±0.4mm; p<0.05) compared to SDCT. Radiation dose from HDCT was comparable to SDCT (1.8±0.7mSv vs. 1.7±0.7mSv; p=ns). Use of HDCT for coronary stent imaging reduces partial volume artefacts from stents yielding improved image quality versus SDCT at a comparable radiation dos

Imaging of heart disease in women: review and case presentation

Cardiovascular diseases (CVD) remain the leading cause of mortality worldwide. Although major diagnostic and therapeutic advances have significantly improved the prognosis of patients with CVD in the past decades, these advances have less benefited women than age-matched men. Noninvasive cardiac imaging plays a key role in the diagnosis of CVD. Despite shared imaging features and strategies between both sexes, there are critical sex disparities that warrant careful consideration, related to the selection of the most suited imaging techniques, to technical limitations, and to specific diseases that are overrepresented in the female population. Taking these sex disparities into consideration holds promise to improve management and alleviate the burden of CVD in women. In this review, we summarize the specific features of cardiac imaging in four of the most common presentations of CVD in the female population including coronary artery disease, heart failure, pregnancy complications, and heart disease in oncology, thereby highlighting contemporary strengths and limitations. We further propose diagnostic algorithms tailored to women that might help in selecting the most appropriate imaging modality

CT coronary angiography: impact of adapted statistical iterative reconstruction (ASIR) on coronary stenosis and plaque composition analysis

To assess the impact of adaptive statistical iterative reconstruction (ASIR) on coronary plaque volume and composition analysis as well as on stenosis quantification in high definition coronary computed tomography angiography (CCTA). We included 50 plaques in 29 consecutive patients who were referred for the assessment of known or suspected coronary artery disease (CAD) with contrast-enhanced CCTA on a 64-slice high definition CT scanner (Discovery HD 750, GE Healthcare). CCTA scans were reconstructed with standard filtered back projection (FBP) with no ASIR (0 %) or with increasing contributions of ASIR, i.e. 20, 40, 60, 80 and 100 % (no FBP). Plaque analysis (volume, components and stenosis degree) was performed using a previously validated automated software. Mean values for minimal diameter and minimal area as well as degree of stenosis did not change significantly using different ASIR reconstructions. There was virtually no impact of reconstruction algorithms on mean plaque volume or plaque composition (e.g. soft, intermediate and calcified component). However, with increasing ASIR contribution, the percentage of plaque volume component between 401 and 500 HU decreased significantly (p < 0.05). Modern image reconstruction algorithms such as ASIR, which has been developed for noise reduction in latest high resolution CCTA scans, can be used reliably without interfering with the plaque analysis and stenosis severity assessment

Investigation of regulatory mechanisms involved in renal and hepatic erythropoietin secretion

Hintergrund: Die Synthese des Glykoproteins Erythropoetin (EPO) korreliert invers mit dem Sauerstoffangebot des arteriellen Blutes und steigt unter Hypoxie bis zu tausendfach. Es wird in der Literatur kontrovers diskutiert, inwieweit das autonome Nervensystem und seine Transmitter, die renale Gewebemenge oder die Durchblutung von Niere und Leber die EPO-Sekretion regulieren. Zielsetzung: In der vorliegenden Arbeit wurde anhand mikrochirurgischer Techniken sowie durch die Gabe verschiedener Neurotransmitter der Einfluss des autonomen Nervensystems, der renalen Gewebemenge und die Durchblutung von Leber und Niere auf die EPO-Sekretion untersucht. Methoden: Alle Versuche wurden in einem Modell Kohlenmonoxid (CO)-induzierter Hypoxie an nicht narkotisierten männlichen Sprague-Dawley Ratten durchgeführt. Hierzu wurde eine Dosis-Wirkungskurve der EPO-Spiegel im Serum, bezogen auf CO-Konzentrationen zwischen 0 und 1400 ppm CO, erstellt. Im ersten Teil der Arbeit wurden die EPO-Konzentration im Serum und die renale EPO-mRNA nach renaler Denervierung und Gabe von Propranolol (unselektiver beta-Adrenozeptorantagonist), Isoproterenol (unselektiver beta-Adrenozeptoragonist), Neuropeptid Y (NPY) und einem NPY-Antagonisten nach CO-Exposition bestimmt. Im zweiten Teil der Arbeit wurde mittels unilateraler oder subtotaler Nephrektomie der Einfluss der renalen Gewebemenge auf die EPO-Produktion untersucht. Die Durchblutung der Niere wurde vor CO-Exposition durch arterielle Stenosierung oder akute und chronische Ureterligatur im dritten Teil der Arbeit verändert. Im vierten Teil wurde geprüft, ob durch Arterialisierung der Leber über einen porto-renalen Shunt die EPO-mRNA-Expression in der Leber verändert werden kann. Teil fünf befasst sich mit den Auswirkungen von Hypoxie auf das Renin-Angiotensin-Aldosteron-System (RAAS). Ergebnisse: Die renale Denervierung bewirkte eine Linksverschiebung der Dosiswirkungskurve mit signifikant erhöhter EPO-Serumkonzentration bei mittlerer hypoxischer Stimulation (600 ppm CO). NPY konnte die Steigerung der EPO-Sekretion denervierter Tiere signifikant senken. NPY-Antagonisten sowie beta-adrenerge Blockade oder Stimulation veränderten die EPO-Sekretion nicht. Die Reduktion der renalen Gewebemasse durch einseitige/subtotale Nephrektomie senkte die EPO-Serumkonzentration und die renale EPO-mRNA-Expression unter starkem hypoxischen Stimulus, nicht jedoch unter milder Hypoxie. Eine akute Ureterligatur steigerte die EPO-Synthese signifikant. Nach chronischer Ligatur des linken Ureters wurde bei 600 ppm CO eine signifikante Verringerung der EPO-Serumkonzentration und des EPO-mRNA-Gehaltes der linken Niere im Vergleich zu Tieren mit akuter Ligatur des linken Ureters gemessen. Eine 70%ige Stenosierung der linken Nierenarterie veränderte EPO-Serumkonzentration und renalen EPO-mRNA-Gehalt nicht. Die EPO-Synthese in der Leber ließ sich durch starke hypoxische Stimulation bei Kontrolltieren um bis zu 28fach steigern. Die EPO-mRNA in der Leber betrug CO-konzentrationsabhängig zwischen 4% bis 7% des renalen EPO-mRNA-Gehaltes. Eine Oxygenierung des Pfortaderblutes vermochte die hepatische EPO-mRNA-Expression nicht zu verändern. Nur für das Modell der subtotalen Nephrektomie konnte eine signifikante Supprimierung der Plasmareninaktivität (PRA) gezeigt werden. Zwischen den übrigen genannten Gruppen waren keine Unterschiede in der PRA zu beobachten. Schlussfolgerung: Unsere Ergebnisse zeigen, dass das renale Nervensystem eine Rolle bei der Regulation der EPO-Sekretion spielt. NPY übt über die renalen Nerven eine tonische Hemmung auf die EPO-Produktion aus. Nach Entfernung von renaler Gewebemasse kann die Restniere bis zu einer Konzentration von 800 ppm CO den Verlust von Epozyten kompensieren. Bei stärkeren hypoxischen Stimuli sinkt die EPO-Synthese. Die renale Hypoperfusion nach Stenosierung der Nierenarterie scheint kein ausreichender Stimulus für eine Steigerung der EPO-Synthese zu sein. Die erhöhte EPO-Produktion nach akuter Ureterligatur lässt vermuten, dass es hierbei durch den gesteigerten renalen Blutfluss (RBF) und folglich erhöhter tubulärer Reabsorptionsarbeit zu einer verstärkten Hypoxie mit vermehrter Stimulation der EPO-produzierenden Zellen kommt. Dagegen führt eine chronische Ureterligatur zu einer Supprimierung der EPO-Produktion. Es bleibt unklar, ob hierfür der Funktionsverlust der EPO-produzierenden Zellen oder ein verminderter O2-Verbrauch der proximalen Tubuli verantwortlich ist. Die Antwort der Leber auf hypoxischen Stimulus erscheint unabhängig vom Sauerstoffgehalt des Pfortaderblutes. Eine Reaktivierung EPO-produzierender Hepatozyten scheint somit nicht möglich zu sein. Nur für das Modell der subtotalen Nephrektomie konnte eine signifikante Senkung der PRA gezeigt werden. Eine Beteiligung des RAAS an der Regulierung der EPO-Synthese ist unter den beschriebenen Versuchsbedingungen unwahrscheinlich.Background: Erythropoietin (EPO), a glycoprotein hormone, is an essential growth factor which regulates erythropoiesis and is predominantly synthesized in the kidneys. EPO secretion and renal mRNA content are inversely correlated to renal oxygen supply. Previous studies have shown that renal ischemia in isolated perfused kidneys elicited a much weaker EPO secretory response compared to systemic hypoxia in vivo, indicating that additional factors may contribute to the EPO secretory response to hypoxia. Despite the fact that several studies investigated the role of renal sympathetic nerves, renal oxygen supply and consumption or reduced renal mass on the regulation of EPO secretion, contradictory results have been reported. Objective: Thus, we re-examined the role of the renal nervous system and its transmitters in carbon monoxide (CO) induced EPO secretion. We further analysed the role of progressive renal disease in the EPO response following CO exposure by using the remnant kidney model. We also investigated the responsiveness of the EPO gene to diminished oxygen consumption in the hydronephrotic kidney, resulting from ureter ligation. In addition, we examined the effect of changes in oxygen supply to kidney and liver on EPO secretion. To clarify the role of the renin-angiotensin-aldosterone system (RAS) on the EPO response, we measured plasma renin activity (PRA) in all experimental groups. Methods: All experiments were carried out in a model of CO induced hypoxia in male Sprague-Dawley rats by constructing a dose response relationship between the degree of hypoxia and EPO secretion. Following bilateral denervation, rats were exposed to different CO concentrations. To compensate the lack of transmitter release in denervated rats we administered [Leu31, Pro34]-Neuropeptide Y (NPY) or isoproteronol. To block these neurotransmitters in control rats we administered the beta-adrenergic receptor blocker propranolol or a specific NPY receptor blocker. In a second set of experiments we compared renal EPO mRNA and EPO serum levels in rats following five-sixths nephrectomy or uninephrectomy with sham-operated controls under conditions of normoxia and hypoxia. Furthermore, we modified renal oxygen consumption and supply by reducing renal blood flow (RBF) below 70% of normal or by performing acute and chronic unilateral ureteral ligation. Finally, we investigated whether portal vein arterialization was able to increase EPO mRNA expression in the liver. In all experimental groups PRA was measured. Results: Serum EPO levels and in parallel renal EPO mRNA expression were elevated in rats with bilateral renal denervation compared to innervated rats following exposure to 600 ppm CO . This increase of EPO secretion in denervated rats could be blocked by administration of NPY, whereas the NPY receptor antagonist did not affect EPO secretion in control animals. Agonists and antagonists of beta-adrenergic receptors had no effect on EPO secretion. Reduction of the renal mass by unilateral or five-sixths nephrectomy exhibited a significant reduced EPO secretory response following severe hypoxic stimulation. The decrease of renal EPO mRNA content was stronger in five-sixths nephrectomized rats compared to unilateral nephrectomized controls. Following CO exposure, acute unilateral ureteral ligation induced a significant raise in EPO serum level and renal EPO mRNA, whereas twenty-four hours of persisting left ureteral ligation significantly decreased EPO serum levels and renal EPO mRNA. Stenosis of the left renal artery with a renal artery clamp did not affect renal EPO mRNA expression and EPO serum levels. Hepatic EPO mRNA content in control animals exposed to different CO concentrations increased up to 28fold compared to baseline concentration. Portal vein arterialization did not affect hepatic EPO mRNA expression. Five-sixths nephrectomy significantly decreased PRA. Conclusion: Our data suggest that renal nerves contribute to the half-maximal EPO secretory response to CO exposure, possibly via NPY receptors. Our results further indicate that the remnant kidney can partially compensate the loss of renal mass, likely due to a hypertrophy of EPO producing cells. Acute unilateral ureteral ligation increased renal EPO production, signifying that there is a direct relationship between EPO production and tubular oxygen consumption. It appears likely that changes in renal morphology in response to chronic ureteral obstruction reduce EPO synthesis, independent of oxygen delivery. The reduced energy-consuming transport activity of the tubular cells in hydronephrotic kidneys may direct affect the synthesis of the hormone. Hepatic oxygen supply seems not to be a dominant factor in the control of hepatic EPO secretion. Our findings indicate that the RAS is influenced by the degree of renal ablation