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Dive into the research topics where George Polymeneas is active.

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Featured researches published by George Polymeneas.


Molecular Carcinogenesis | 2013

Expression of microRNAs, miR-21, miR-31, miR-122, miR-145, miR-146a, miR-200c, miR-221, miR-222, and miR-223 in patients with hepatocellular carcinoma or intrahepatic cholangiocarcinoma and its prognostic significance.

Andreas Karakatsanis; Ioannis Papaconstantinou; Maria Gazouli; Anna Lyberopoulou; George Polymeneas; Dionysios Voros

MicroRNAs are a class of non‐coding molecules found to regulate a variety of cellular functions in health and disease. Dysregulation of microRNAs is involved in liver disease, especially hepatocarcinogenesis. Since primary hepatic malignancies are typically characterized by late diagnosis, frequent recurrence, and poor response to adjuvant therapy, there is a need for the discovery of novel biomarkers in order to achieve earlier diagnosis, predict tumor aggressiveness and response to adjuvant therapy. The purpose of this study is to evaluate the expression of certain microRNAs (miR‐21, ‐31, ‐122, ‐145, ‐146a, ‐ 200c, ‐221, ‐222 and ‐223) in patients with hepatocellular carcinoma (HCC) and intrahepatic cholangiocarcinoma (ICC), as well as to assess their prognostic significance. Micro‐RNA expression was assessed by reverse transcription and real‐time PCR (RT‐PCR). Clinicopathological data and survival rates were retrieved and analyzed. According to our results, miR‐21, miR‐31, miR‐122, miR‐221, miR‐222 were significantly up‐regulated in HCC tissues, whereas miR‐145, miR‐146a, miR‐200c, and miR‐223 were found to be down‐regulated. Concerning ICC samples, miR‐21, miR‐31, and miR‐223 were found to be over‐expressed, whereas miR‐122, miR‐145, miR‐200c, miR‐221, and miR‐222 were down‐regulated. Additionally, expression of miR‐21, miR‐31, miR‐122, and miR‐221 in HCC correlated with cirrhosis, while miR‐21 and miR‐221 associated with tumor stage and poor prognosis. In ICC tissues, miR‐21, miR‐31, and miR‐223 were found to be over‐expressed, but no correlation with clinicopathological features was found.


European Journal of Gastroenterology & Hepatology | 2012

The role of microRNAs in liver cancer.

Ioannis Papaconstantinou; Andreas Karakatsanis; Maria Gazouli; George Polymeneas; Dionissios Voros

Hepatocellular carcinoma and cholangiocarcinoma constitute the majority of primary malignant tumors located in the liver, with hepatocellular carcinoma accounting for approximately 80% of these tumors and cholangiocarcinoma representing the remaining 20%. Both are aggressive malignancies, heterogeneous in terms of biological activities and clinical behavior, with dismal outcomes and an increasing incidence worldwide. Radical surgical resection remains the gold standard to date, as adjuvant therapeutic modalities have failed to show a consistent and adequate curative response. However, radical surgical resection is not feasible in most of the patients with such tumors, as tumor size or functional status of the parenchyma does not permit extended hepatic resection. In addition, patients who undergo curative resection often have a high rate of relapse. Multimodal therapeutic approaches, such as the combination of invasive methods (surgical resection, radiofrequency ablation, and two-step or three-step procedures with intermittent portal vein embolization) with interferon-&agr;, systemic chemotherapy, or transarterial catheter embolization, may prolong survival in some patients, but have, however, failed to demonstrate satisfactory results. Therefore, an obvious need emerges for the discovery of new biomarkers to understand the events leading to hepatocarcinogenesis, to relate different phenotypes with differences in clinical behavior and prognosis, and, if possible, to predict response rates to adjuvant therapeutic modalities or, furthermore, to establish novel mechanism-based treatments for hepatic tumors.


Korean Journal of Parasitology | 2012

Two Cases of Primary Splenic Hydatid Cyst in Greece

Antonios Vezakis; Dionysios Dellaportas; George Polymeneas; Marios Konstantinos Tasoulis; Constantinos Chondrogiannis; Aikaterini Melemeni; Andreas Polydorou; George Fragulidis

Cystic disease of the spleen is an uncommon entity in general population. Most cases result from parasitic infection by Echinococcus granulosus, a form called splenic hydatid disease (SHD), with a reported frequency of 0.5-6.0% within abdominal hydatidosis. On the contrary, an isolated splenic involvement of hydatid disease is very uncommon even in endemic regions. Two cases of primary SHD managed with open and laparoscopic radical surgery in our department are reported herein. Primary SHD is a rare entity with non-specific symptoms underlying clinical suspicion by the physician for prompt diagnosis. Surgical treatment is the mainstay therapy, while laparoscopic approach when feasible is safe, offering the advantages of laparoscopic surgery.


World Journal of Gastrointestinal Surgery | 2012

Solitary rectal cap polyp: Case report and review of the literature

Ioannis Papaconstantinou; Andreas Karakatsanis; Xanthi Benia; George Polymeneas; Evanthia Kostopoulou

Rectal bleeding combined with the presence of a rectal mass has been traditionally associated with the presence of malignant disease. Cap polyposis is a relatively young and still undefined rare entity which mainly involves the rectosigmoid. It is characterized by the presence of inflammatory polyps. In this case report, we present a patient who was diagnosed with a solitary cap polyp of the rectum during the investigation of a bleeding rectal mass. The patients age and the absence of family history were not in favor of malignancy, despite the strong initial clinical impression. After confirmation of the diagnosis, the patient underwent a snare excision and remains asymptomatic. Cap polyposis, although rare, should be suspected and, when diagnosed, should be treated according to location, number of polyps and severity of symptoms.


Journal of Surgical Research | 2009

Sutureless Pancreatojejunal Anastomosis Using an Absorbable Sealant: Evaluation in a Pig Model

Eriphili Argyra; George Polymeneas; Eleni Karvouni; Nikolaos Kontorravdis; Theodosios Theodosopoulos; Nikolaos Arkadopoulos

BACKGROUND Leakage from pancreatojejunal anastomosis continues to be a major source of morbidity in pancreatic surgery. In the present study, we test the hypothesis that a safe, sutureless pancreatojejunal anastomosis can be constructed using a synthetic surgical sealant. MATERIALS AND METHODS Ten pigs weighing 20 to 25 kg underwent distal pancreatectomy and anastomosis of the pancreatic remnant with a jejunal limb with the use of an absorbable surgical sealant. Integrity of the anastomosis was checked on the 10th postoperative d by means of an autopsy study and histological examination. RESULTS One animal died on the 3rd postoperative d of peritonitis. The remaining 9 animals had an uneventful postoperative course. Gross and microscopic pathological examination revealed intact pancreatojejunal anastomosis in all surviving animals. CONCLUSIONS Following distal pancreatectomy in pigs, pancreatojejunal anastomoses with the use of sealant are technically feasible. During a 10-d observation period, the sealant appeared to prevent anastomotic dehiscence and allow normal anastomotic healing.


International Journal of Surgery Case Reports | 2014

Methods of safe laparoscopic cholecystectomy for left-sided (sinistroposition) gallbladder: A report of two cases and a review of safe techniques

Constantinos Nastos; Antonios Vezakis; Ioannis Papaconstantinou; Theodosios Theodosopoulos; Vassilios Koutoulidis; George Polymeneas

INTRODUCTION Left-sided gallbladder is a rare anatomical variation. Usually it is discovered intra-operatively and is accompanied by anatomic variations that can prove quite challenging during laparoscopy. PRESENTATION OF CASE From a total of almost 3000 laparoscopic cholecystectomies performed in our institution, two cases of left sided gallbladder were unexpectantly identified intraoperatively. There were no indications for the ectopy preoperatively. In both cases modifications of the standard laparoscopic technique were mandatory. They were performed safely with no post-operative complications. Modifications consisted of transposition of the subxiphoid entry port and alteration in the direction of traction of the rest of the graspers. A review of the literature for methods of safe laparoscopic cholecystectomy was conducted. DISCUSSION The surgeon must be aware of the anatomic variances in the rare occasion of a left sided gallbladder, since preoperative diagnosis is very difficult. CONCLUSION Knowledge of potential hazards and modifications of laparoscopic technique is mandatory in order to avoid complications.


International Scholarly Research Notices | 2013

Pancreatic Remnant Occlusion after Whipple's Procedure: An Alternative Oncologically Safe Method.

Theodosios Theodosopoulos; Dionysios Dellaportas; Anneza Yiallourou; George Gkiokas; George Polymeneas; Alexios Fotopoulos

Introduction. To present our experience regarding the use of pancreatic stump occlusion technique as an alternative management of the pancreatic remnant after pancreatoduodenectomy (PD). Methods. Between 2002 and 2009, hospital records of 93 patients who had undergone a Whipples procedure for either pancreatic-periampullary cancer or chronic pancreatitis were retrospectively studied. In 37 patients the pancreatic duct was occluded by stapling and running suture without anastomosis of the pancreatic remnant, whereas in 56 patients a pancreaticojejunostomy was performed. Operative data, postoperative complications, oncological parameters, and survival rates were recorded. Results. 2/37 patients of the occlusion group and 9/56 patients of the anastomosis group were treated for chronic pancreatitis, whereas 35/37 and 47/56 patients for periampullary malignancies. The duration of surgery for the anastomosis group was significantly longer (mean time 220 versus 180 minutes). Mean hospitalization time was 6 days for both groups. The occlusion group had a lower morbidity rate (24% versus 32%). With regard to postoperative complications, a slightly higher incidence of pancreatic fistulas was observed in the anastomosis group. Conclusions. Pancreatic remnant occlusion is a safe, technically feasible, and reducing postoperative complications alternative approach of the pancreatic stump during Whipples procedure.


World Journal of Surgical Oncology | 2011

Concurrent insulinoma and pancreatic adenocarcinoma: report of a rare case and review of the literature

Panagiotis G Athanasopoulos; George Polymeneas; Dionysios Dellaportas; George Mastorakos; Evi Kairi; Dionysios Voros

Pancreatic adenocarcinoma is the 5th leading cause of cancer-related death in Western countries and insulinomas are rare endocrine neoplasms of the pancreas. The concurrent appearance of pancreatic adenocarcinoma and insulinoma is very rare and to the best of our knowledge has never been reported again. Herein, we present such an occurrence in a 74-year-old man. Resection of a mass in the uncinate process of the pancreas revealed pancreatic adenocarcinoma with severe desmoplastic reaction. Two years later, due to symptomatology persistence the patient was re-examined and a new 2cm mass in the uncinate process was found leading to surgery, which demonstrated a 2cm endocrine islet-cell tumor. Establishing a diagnosis in patients with insulinoma is difficult and the imaging studies still have low sensitivity and specificity except for intra-operative ultrasonography, which is the most accurate method detecting 90% of these lesions.


World Journal of Surgical Oncology | 2012

Right Kocher’s incision: a feasible and effective incision for right hemicolectomy: a retrospective study

Theodosios Theodosopoulos; Anneza Yiallourou; Nicolaos Dafnios; George Polymeneas; Ioannis Papaconstantinou; Chrysoula Staikou; Ioannis Vassiliou; Vassilis Smyrniotis; Alexios Fotopoulos

BackgroundThe choice of surgical incision is determined by access to the surgical field, particularly when an oncological resection is required. Special consideration is also given to other factors, such as postoperative pain and its sequelae, fewer complications in the early postoperative period and a lower occurrence of incisional hernias. The purpose of this study is to compare the right Kocher’s and the midline incision, for patients undergoing right hemicolectomy, by focusing on short- and longterm results.MethodsBetween 1995 and 2009, hospital records for 213 patients that had undergone a right hemicolectomy for a right- sided adenocarcinoma were retrospectively studied. 113 patients had been operated via a Kocher’s and 100 via a midline incision. Demographic details, operative data (explorative access to the peritoneal cavity, time of operation), recovery parameters (time with IV analgesic medication, time to first oral fluid intake, time to first solid meal, time to discharge), and oncological parameters (lymph node harvest, TNM stage and resection margins) were analyzed. Postoperative complications were also recorded. The two groups were retrospectively well matched with respect to demographic parameters and oncological status of the tumor.ResultsThe median length of the midline incision was slightly longer (12 vs. 10 cm, p < 0.05). The duration of the surgery for the Kocher’s incision group was significantly shorter (median time 70 vs 85 min, p < 0.001). In three patients we performed wedge resection of liver metastasis and in one patient we performed a typical right hepatectomy that lasted 190 min. No major operative complications were noted. There was no immediate or 30- day postoperative mortality. The Kocher’s incision group had a significantly shorter hospital stay (median time 5 vs 8 days). All patients underwent wide tumor excision and clear resection margins were obtained in all cases. No significant difference was noted regarding analgesia requirements and early postoperative complications. Late postoperative complications included 2 incisional hernias and three patients presented with one episode of obstructive ileus, that resolved conservatively.ConclusionsThe Kocher’s incision approach for right- sided colon cancer is technically feasible, safe and overall very well tolerated. It can achieve the same standards of tumor resection and surgical field accessibility as the midline approach, while reducing postoperative recovery.


Case Reports in Surgery | 2012

Strangulated femoral hernia turned to be peritoneal cyst.

Dionysios Dellaportas; George Polymeneas; Christina Dastamani; Evi Kairi-Vasilatou; Ioannis Papaconstantinou

Introduction. A peritoneal inclusion cyst is a very rare mesenteric cyst of mesothelial origin usually asymptomatic. A rare case of an 82-year-old white Caucasian female with a femoral hernia containing a large peritoneal inclusion cyst, mimicking strangulated hernia, is presented herein. Case Presentation. The patient was admitted to our hospital suffering from a palpable groin mass on the right, which became painful and caused great discomfort for the last hours. Physical examination revealed a tender and tense, irreducible groin mass. An inguinal operative approach was selected and the mass was found protruding through the femoral ring. After careful dissection it turned out to be a large unilocular cyst, containing serous fluid, probably originating from the peritoneum. McVay procedure was used to reapproximate the femoral ring. Histologic examination showed a peritoneal inclusion cyst. Discussion. Peritoneal inclusion cysts are usually asymptomatic but occasionally present with various, nonspecific symptoms according to their size. Our case highlights that high index of clinical suspicion and careful exploration during repair of a hernia is mandatory in order to reach the correct diagnosis about hernias contents.

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Ioannis Papaconstantinou

National and Kapodistrian University of Athens

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Anneza Yiallourou

National and Kapodistrian University of Athens

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Dionysios Voros

National and Kapodistrian University of Athens

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Theodosios Theodosopoulos

National and Kapodistrian University of Athens

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Dionysios Dellaportas

National and Kapodistrian University of Athens

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Alexios Fotopoulos

National and Kapodistrian University of Athens

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Andreas Karakatsanis

National and Kapodistrian University of Athens

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Andreas Polydorou

National and Kapodistrian University of Athens

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Antonios Vezakis

National and Kapodistrian University of Athens

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