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Search Results: 1 - 10 of 32442 matches for " Stathopoulos John "
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Modification of the No-Touch Technique during Renal Artery Stenting
John A. Stathopoulos
Case Reports in Vascular Medicine , 2013, DOI: 10.1155/2013/516267
Abstract: Renal artery stenting has been established as the primary form of renal artery stenosis revascularization procedure. The no-touch technique is proposed in order to avoid renal artery injury and atheroembolism during renal artery stenting. We describe a modification of the no-touch technique by using an over-the-wire (OTW) balloon or a Quickcross catheter with a coronary wire inside, instead of the rigid ?J wire. The reported technique, while it prevents direct contact of the guiding catheter with the aortic wall, at the same time it allows for a closer contact with the renal arterial ostium and a more favorable guiding catheter orientation, compared to what is achieved with the use of the more rigid ?J wire, thus improving visualization, reducing the amount of contrast required, and potentially decreasing complications. 1. Introduction Renal artery stenting has been widely used for the treatment of renal artery stenosis. The technical aspects of stenting have improved over the last years, and procedural safety is recognized as of paramount importance. Two invasive techniques are proposed in order to avoid renal artery injury and atheroembolism during renal artery stenting [1]: the catheter-in-catheter and the so-called no-touch technique. The no-touch technique [2] uses a ?J wire inside the guiding catheter, to lift the tip off the aortic wall. With the wire in place, the guiding catheter is aligned with the renal artery, and a guidewire is used to cross the stenosis. The wire is then removed, and the guiding catheter is advanced over the wire to engage the renal artery. We report a modification of the no-touch technique by using an over-the-wire (OTW) balloon or a Quickcross catheter (Spectranetics) with a coronary wire inside, instead of the rigid ?J wire. 2. Case 1 A 67-year-old lady, with uncontrolled severe hypertension despite therapy, peripheral arterial disease (PAD), and left ventricular hypertrophy was diagnosed with right renal artery stenosis and referred for renal angiography. An abdominal aortogram confirmed the presence of significant right renal artery stenosis. Renal percutaneous transluminal angioplasty (PTA) was then undertaken. The procedural steps were as follows.(1)A 6F internal mammary artery (IMA) guiding catheter (Launcher, Medtronic) was introduced and was placed at the level of the right renal artery but pointed away of the right renal artery ostium, without touching the aortic wall.(2)A Balance (Abbott) coronary wire in a Quickcross catheter (Spectranetics) was introduced in the 6F guiding catheter with the tip of the wire
LIPOSOMAL CISPLATIN IN CANCER PATIENTS WITH RENAL FAILURE
Stathopoulos P. George,Rigatos Sotiris,Stathopoulos John,Batzios Spyros
Journal of Drug Delivery and Therapeutics , 2012,
Abstract: One of the serious adverse reactions with the administration of chemotherapeutical agents is renal failure. In general, when the level of creatinine/glomerular filtration data is high, chemotherapy involving almost all cytotoxic agents is avoided or the dosage is reduced. Liposomal cisplatin (lipoplatin) is a new agent which has been tested in Phase I, II and III trials and norenal toxicity has been reported. In the present trial, this agent was tested as monotherapy and in combination with gemcitabine or paclitaxel or 5-fluorouracil-leucovorin, mainly in lung and bladder cancer patients with renal insufficiency. Forty-two patients, (14 with non-small-cell lung cancer, 2 with squamous cell carcinoma non-small-cell lung cancer, 16 with bladder cancer and 10 gastrointestinal tract cancer), were included. There were 40 men and 2 women, median age 65 y (range 49-84). Lipoplatin and gemcitabine were administered to patients with bladder cancer, the first day, repeated every 2 weeks; paclitaxel, plus lipoplatin as above, were administered to lung cancer patients; patients with gastrointestinal tract cancer received 5-fluorouracil and leucovorin, plus lipoplatin as above. The median number of courses was 6 (range 2-12). Serum creatinine was 1.6 mg/dl to 4.0 mg/dl (median 2.4 mg/dl). No serum creatinine increase was observed in any of the patients. Grade 1-2 myelotoxicity and anemia were observed in 28.57% and 50% of the patients, respectively. Liposomal cisplatin is a new agent, which according to the literature and the present study, is an eligible cytotoxic agent for patients with renal insufficiency.
Conservative treatment of an anterior-lateral ankle dislocation without an associated fracture in a diabetic patient: a case report
Panagiotis K. Karampinas,Ioannis P. Stathopoulos,John Vlamis,Vasilios D. Polyzois
Diabetic Foot & Ankle , 2012, DOI: 10.3402/dfa.v3i0.18411
Abstract: Anterior or anterior-lateral dislocation of the ankle is a rare condition that can be treated conservatively as well as any other similar types of ankle dislocations without associated fractures. We present a case report of an anterior-lateral ankle dislocation with a concomitant avulsion injury of the ankle's anterior capsule in a diabetic patient that was treated conservatively. At the patient's visit 12 months after the initial injury, he was asymptomatic with full range of motion of the ankle joint. To our knowledge, we could not identify this type of an injury in a diabetic patient that was treated successfully with conservative treatment in the existing literature.
Predictive Value of BRCA1, ERCC1, ATP7B, PKM2, TOPOI, TOPΟ-IIA, TOPOIIB and C-MYC Genes in Patients with Small Cell Lung Cancer (SCLC) Who Received First Line Therapy with Cisplatin and Etoposide
Niki Karachaliou, Chara Papadaki, Eleni Lagoudaki, Maria Trypaki, Maria Sfakianaki, Anastasios Koutsopoulos, Dimitris Mavroudis, Efstathios Stathopoulos, Vassilis Georgoulias, John Souglakos
PLOS ONE , 2013, DOI: 10.1371/journal.pone.0074611
Abstract: Background The aim of the study was to evaluate the predictive value of genes involved in the action of cisplatin-etoposide in Small Cell Lung Cancer (SCLC). Methods 184 SCLC patients’ primary tumour samples were analyzed for ERCCI, BRCA1, ATP7B, PKM2 TOPOI, TOPOIIA, TOPOIIB and C-MYC mRNA expression. All patients were treated with cisplatin-etoposide. Results The patients’ median age was 63 years and 120 (65%) had extended stage, 75 (41%) had increased LDH serum levels and 131 (71%) an ECOG performance status was 0-1. Patients with limited stage, whose tumours expressed high ERCC1 (p=0.028), PKM2 (p=0.046), TOPOI (p=0.008), TOPOIIA (p=0.002) and TOPOIIB (p<0.001) mRNA had a shorter Progression Free Survival (PFS). In limited stage patients, high expression of ERCC1 (p=0.014), PKM2 (p=0.026), TOPOIIA (p=0.021) and TOPOIIB (p=0.019) was correlated with decreased median overall survival (mOS) while in patients with extended stage, only high TOPOIIB expression had a negative impact on Os (p=0.035). The favorable expression signature expression signature (low expression of ERCC1, PKM2, TOPOIIA and TOPOIIB) was correlated with significantly better PFS and Os in both LS-SCLC (p<0.001 and p=0.007, respectively) and ES-SCLC (p=0.007 and (p=0.011, respectively) group. The unfavorable expression signature was an independent predictor for poor PFS (HR: 3.18; p=0.002 and HR: 3.14; p=0.021) and Os (HR: 4.35; p=0.001and HR: 3.32; p=0.019) in both limited and extended stage, respectively. Conclusions Single gene’s expression analysis as well as the integrated analysis of ERCC1, PKM2, TOPOIIA and TOPOIIB may predict treatment outcome in patients with SCLC. These findings should be further validated in a prospective study.
Dynamic Interpretation of Hedgehog Signaling in the Drosophila Wing Disc
Marcos Nahmad,Angelike Stathopoulos
PLOS Biology , 2012, DOI: 10.1371/journal.pbio.1000202
Abstract: Morphogens are classically defined as molecules that control patterning by acting at a distance to regulate gene expression in a concentration-dependent manner. In the Drosophila wing imaginal disc, secreted Hedgehog (Hh) forms an extracellular gradient that organizes patterning along the anterior–posterior axis and specifies at least three different domains of gene expression. Although the prevailing view is that Hh functions in the Drosophila wing disc as a classical morphogen, a direct correspondence between the borders of these patterns and Hh concentration thresholds has not been demonstrated. Here, we provide evidence that the interpretation of Hh signaling depends on the history of exposure to Hh and propose that a single concentration threshold is sufficient to support multiple outputs. Using mathematical modeling, we predict that at steady state, only two domains can be defined in response to Hh, suggesting that the boundaries of two or more gene expression patterns cannot be specified by a static Hh gradient. Computer simulations suggest that a spatial “overshoot” of the Hh gradient occurs, i.e., a transient state in which the Hh profile is expanded compared to the Hh steady-state gradient. Through a temporal examination of Hh target gene expression, we observe that the patterns initially expand anteriorly and then refine, providing in vivo evidence for the overshoot. The Hh gene network architecture suggests this overshoot results from the Hh-dependent up-regulation of the receptor, Patched (Ptc). In fact, when the network structure was altered such that the ptc gene is no longer up-regulated in response to Hh-signaling activation, we found that the patterns of gene expression, which have distinct borders in wild-type discs, now overlap. Our results support a model in which Hh gradient dynamics, resulting from Ptc up-regulation, play an instructional role in the establishment of patterns of gene expression.
Lateral Gene Expression in Drosophila Early Embryos Is Supported by Grainyhead-Mediated Activation and Tiers of Dorsally-Localized Repression
Mayra Garcia, Angelike Stathopoulos
PLOS ONE , 2011, DOI: 10.1371/journal.pone.0029172
Abstract: The general consensus in the field is that limiting amounts of the transcription factor Dorsal establish dorsal boundaries of genes expressed along the dorsal-ventral (DV) axis of early Drosophila embryos, while repressors establish ventral boundaries. Yet recent studies have provided evidence that repressors act to specify the dorsal boundary of intermediate neuroblasts defective (ind), a gene expressed in a stripe along the DV axis in lateral regions of the embryo. Here we show that a short 12 base pair sequence (“the A-box”) present twice within the ind CRM is both necessary and sufficient to support transcriptional repression in dorsal regions of embryos. To identify binding factors, we conducted affinity chromatography using the A-box element and found a number of DNA-binding proteins and chromatin-associated factors using mass spectroscopy. Only Grainyhead (Grh), a CP2 transcription factor with a unique DNA-binding domain, was found to bind the A-box sequence. Our results suggest that Grh acts as an activator to support expression of ind, which was surprising as we identified this factor using an element that mediates dorsally-localized repression. Grh and Dorsal both contribute to ind transcriptional activation. However, another recent study found that the repressor Capicua (Cic) also binds to the A-box sequence. While Cic was not identified through our A-box affinity chromatography, utilization of the same site, the A-box, by both factors Grh (activator) and Cic (repressor) may also support a “switch-like” response that helps to sharpen the ind dorsal boundary. Furthermore, our results also demonstrate that TGF-β signaling acts to refine ind CRM expression in an A-box independent manner in dorsal-most regions, suggesting that tiers of repression act in dorsal regions of the embryo.
Analysis of Thisbe and Pyramus functional domains reveals evidence for cleavage of Drosophila FGFs
Sarah Tulin, Angelike Stathopoulos
BMC Developmental Biology , 2010, DOI: 10.1186/1471-213x-10-83
Abstract: In this work, we conducted an analysis of the functional domains of two Drosophila proteins, Thisbe (Ths) and Pyramus (Pyr), which share homology with the FGF8 subfamily of ligands in vertebrates. Ths and Pyr proteins are secreted from Drosophila Schneider cells (S2) as smaller N-terminal fragments presumably as a result of intracellular proteolytic cleavage. Cleaved forms of Ths and Pyr can be detected in embryonic extracts as well. The FGF-domain is contained within the secreted ligand portion, and this domain alone is capable of functioning in the embryo when ectopically expressed. Through targeted ectopic expression experiments in which we assay the ability of full-length, truncated, and chimeric proteins to support cell differentiation, we find evidence that (1) the C-terminal domain of Pyr is retained inside the cell and does not seem to be required for receptor activation and (2) the C-terminal domain of Ths is secreted and, while also not required for receptor activation, this domain does plays a role in limiting the activity of Ths when present.We propose that differential protein processing may account for the previously observed inequalities in signaling capabilities between Ths and Pyr. While the regulatory mechanisms are likely complex, studies such as ours conducted in a tractable model system may be able to provide insights into how ligand processing regulates growth factor activity.Fibroblast Growth Factors (FGFs) comprise a large family of signalling molecules that are key regulators of developmental processes including mesoderm induction, gastrulation, cell migration, midbrain-hindbrain patterning, limb induction and bone formation [1-7]. FGFs continue to function in adult tissue homeostasis and wound healing; when improperly activated they can also contribute to many human diseases and cancer [7-10]. Most of the 24 known FGF ligands in vertebrates are small proteins with a molecular mass of 17-34 kD, whereas the three known Drosophila FGF ligands
Standards for Quantitative Assessment of Lung Structure: The Dawn of Stereopneumology
Georgios T. Stathopoulos
Pneumon , 2010,
Abstract: SUMMARY. The lungs are complex 3D structuresstudied in the clinic and the laboratory using histologic or imaging sections. Although such 2D analyses of lung structure are considered “gold standards”, the information conveyed is often insufficient and does not represent the whole organ. Stereology, the mathematical approach to the analysis of 3D structures via 2D sampling and morphometry, the practical application of stereology, provide solutions to this problem, but had until recently not been systematically adoptedin pneumology. In an effort of minimizing the above-mentioned methodological problems and of standardizing the quantitative assessment of lung structure, the American Thoracic Society and European Respiratory Society formed a task force, which recently published its findings. The task force aimed at comprehensively reviewing current stereologic methods for lung morphometry, formulating practical guidelines for using unbiased methods for basic and translational research of lung structure, and examining the extensions of stereologic methods on non-invasive imaging of lung architecture. In the statement of the task force are included useful directives with important application in the laboratory and the clinic, the most pertinent of which are discussed in the present mini-review. Pneumon 2010, 23(2):141-152.
Dynamic Interpretation of Hedgehog Signaling in the Drosophila Wing Disc
Marcos Nahmad,Angelike Stathopoulos
PLOS Biology , 2009, DOI: 10.1371/journal.pbio.1000202
Abstract: Morphogens are classically defined as molecules that control patterning by acting at a distance to regulate gene expression in a concentration-dependent manner. In the Drosophila wing imaginal disc, secreted Hedgehog (Hh) forms an extracellular gradient that organizes patterning along the anterior–posterior axis and specifies at least three different domains of gene expression. Although the prevailing view is that Hh functions in the Drosophila wing disc as a classical morphogen, a direct correspondence between the borders of these patterns and Hh concentration thresholds has not been demonstrated. Here, we provide evidence that the interpretation of Hh signaling depends on the history of exposure to Hh and propose that a single concentration threshold is sufficient to support multiple outputs. Using mathematical modeling, we predict that at steady state, only two domains can be defined in response to Hh, suggesting that the boundaries of two or more gene expression patterns cannot be specified by a static Hh gradient. Computer simulations suggest that a spatial “overshoot” of the Hh gradient occurs, i.e., a transient state in which the Hh profile is expanded compared to the Hh steady-state gradient. Through a temporal examination of Hh target gene expression, we observe that the patterns initially expand anteriorly and then refine, providing in vivo evidence for the overshoot. The Hh gene network architecture suggests this overshoot results from the Hh-dependent up-regulation of the receptor, Patched (Ptc). In fact, when the network structure was altered such that the ptc gene is no longer up-regulated in response to Hh-signaling activation, we found that the patterns of gene expression, which have distinct borders in wild-type discs, now overlap. Our results support a model in which Hh gradient dynamics, resulting from Ptc up-regulation, play an instructional role in the establishment of patterns of gene expression.
Computing and deflating eigenvalues while solving multiple right hand side linear systems in Quantum Chromodynamics
Andreas Stathopoulos,Kostas Orginos
Physics , 2007, DOI: 10.1137/080725532
Abstract: We present a new algorithm that computes eigenvalues and eigenvectors of a Hermitian positive definite matrix while solving a linear system of equations with Conjugate Gradient (CG). Traditionally, all the CG iteration vectors could be saved and recombined through the eigenvectors of the tridiagonal projection matrix, which is equivalent theoretically to unrestarted Lanczos. Our algorithm capitalizes on the iteration vectors produced by CG to update only a small window of vectors that approximate the eigenvectors. While this window is restarted in a locally optimal way, the CG algorithm for the linear system is unaffected. Yet, in all our experiments, this small window converges to the required eigenvectors at a rate identical to unrestarted Lanczos. After the solution of the linear system, eigenvectors that have not accurately converged can be improved in an incremental fashion by solving additional linear systems. In this case, eigenvectors identified in earlier systems can be used to deflate, and thus accelerate, the convergence of subsequent systems. We have used this algorithm with excellent results in lattice QCD applications, where hundreds of right hand sides may be needed. Specifically, about 70 eigenvectors are obtained to full accuracy after solving 24 right hand sides. Deflating these from the large number of subsequent right hand sides removes the dreaded critical slowdown, where the conditioning of the matrix increases as the quark mass reaches a critical value. Our experiments show almost a constant number of iterations for our method, regardless of quark mass, and speedups of 8 over original CG for light quark masses.
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