I. Celik
University of Marburg
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Featured researches published by I. Celik.
Annals of Surgery | 2005
Detlef K. Bartsch; Volker Fendrich; Peter Langer; I. Celik; Peter Herbert Kann; M. Rothmund
Objective:To evaluate the outcome of an aggressive surgical approach for duodenopancreatic neuroendocrine tumors (PETs) associated with multiple endocrine neoplasia type 1 (MEN1). Summary Background Data:The management of PETs is still controversial in the setting of the autosomal dominant inherited MEN1 syndrome. Methods:MEN1 patients that had either biochemical evidence of functioning PETs or visualized nonfunctioning PETs larger than 1 cm in size on imaging were operated. Since 1997, patients were followed annually by biochemical testing and imaging studies. Results:Twenty-six genetically confirmed MEN1 patients underwent duodenopancreatic resection for functioning (n = 17) or nonfunctioning (n = 9) PETs. Ten (38%) patients had malignant PETs as characterized by the presence of lymph node (10 patients) and/or distant metastases (2 patients). The surgical approach was selected based on the type, location, and size of PETs. Four Zollinger-Ellison syndrome (ZES) patients required pylorus preserving pancreaticoduodenectomy (PPPD) as initial or redo procedure, 20 patients underwent other duodenopancreatic resections, and 2 patients had simple enucleations of PETs. After median 83 months (range, 5–241 months), 24 patients were alive and 2 patients died of an unrelated cause. All patients with insulinoma or vipoma and 7 of 11 patients with ZES were biochemically cured, including the ZES patients who underwent PPPD. However, 19 of 26 (73%) patients developed new small PETs (<1 cm) in the pancreatic remnant, but no patient had yet detectable metastases on imaging. Conclusions:Early and aggressive surgery of PETs in MEN1 patients prevents the development of liver metastases, which are the most life-threatening determinant. PPPD might be the procedure of choice for MEN1–ZES, which has to be proven in large scale studies.
Annals of Surgery | 2006
Volker Fendrich; Peter Langer; I. Celik; Detlef K. Bartsch; A. Zielke; Anette Ramaswamy; M. Rothmund
Objective:To evaluate the outcome of reoperations in patients with duodenopancreatic neuroendocrine tumors (PETs) in a tertiary referral center. Summary Background Data:The management of reoperations in PETs is still controversial. Methods:A total of 125 patients with PETs that underwent surgery between 1987 and 2004 at our institution were retrospectively evaluated. The diagnosis of PETs was based on clinical symptoms, biochemical tests, and histopathology. Patients with at least one reoperation were analyzed regarding clinical characteristics, pathology, operations, and long-term follow-up. Results:A total of 33 patients with a median age of 42 years were identified for this study: 13 patients had gastrinomas, 12 patients had nonfunctional islet cell tumors, 6 patients had insulinomas, and 2 patients had vipomas; 24 patients had sporadic NETs, 9 patients had a MEN-1-syndrome; 27 patients had histologically verified malignant tumors; 33 initial operations and 50 reoperations were performed. The initial procedures comprised 27 resections of the primary tumor and 6 explorative laparotomies; 28 of all reoperations were resections of distant metastases, including 15 liver resections; 19 resections of the pancreas or duodenum were performed during reoperations. The overall morbidity and mortality was 45% and 4.8%, respectively. After a median follow-up of 124 months (range, 16–384 months), 27 of 33 patients are still alive, 12 without evidence of disease. All 6 patients with benign tumors are still alive. The 5-, 10-, and actuarial 25-year survival rate for patients with malignant tumors were 81%, 72%, and 36%, respectively. The survival rate was significantly related to the patients age at time of initial operation and better in patients younger than 50 years compared with patients older than 50 years (P = 0.0007), and the presence or development of metastases (none or lymph node metastases versus distant metastases: P = 0.01). Conclusion:We show that an aggressive surgical approach leads to long-term survival in patients with malignant PETs. Although long-term cure can only be achieved in a proportion of patients with malignant PETs, significant long-term palliation can be achieved.
Cancer Research | 2005
I. Celik; Oguzkan Sürücü; Carsten Dietz; John V. Heymach; Jeremy Force; Iris Höschele; Christian M. Becker; Judah Folkman; Oliver Kisker
We show here that recombinant endostatin protein has a biphasic effect on the inhibition of endothelial cell migration in vitro. In tumor-bearing animals, there is a similar biphasic effect on the inhibition of tumor growth and on circulating endothelial cells after once-daily s.c. injections. This biphasic effect is revealed as a U-shaped curve in which efficacy is optimal between very low and very high doses depending on the tumor type. This result may be applicable to other inhibitors of endothelial growth and to angiogenesis. Furthermore, these results have important implications for clinicians who administer angiogenesis inhibitors for cancer or other angiogenesis-dependent diseases. When these results are taken together with two previous reports of angiogenesis inhibitors with a U-shaped dose-response, they suggest that other regulators of endothelial growth may display a similar pattern.
World Journal of Surgery | 2000
Detlef K. Bartsch; Thomas Schilling; Annette Ramaswamy; Berthold Gerdes; I. Celik; Hans-Joachim Wagner; Babette Simon; M. Rothmund
Tumors arising from the pancreatic islet cells are rare and represent a heterogeneous group of benign or malignant lesions. Most tumors present with well characterized syndromes, whereas others appear to be nonfunctioning. The clinical features of 11 men and 7 women with nonfunctioning islet cell carcinomas operated on between 1983 and 1998 were reviewed. The median patient age was 53.5 years (range 26–74 years). The most frequent presenting symptoms were abdominal pain (13 patients), weight loss (7 patients), and obstructive jaundice (4 patients). Gut hormone profiles were normal in all patients. Abdominal sonography and computed tomography localized the tumor in 17 patients, and correct prediction of an endocrine tumor was achieved in 12 patients. Six of seven patients showed a hypervascular tumor upon angiograpy, and seven of eight patients preoperatively had positive somatostatin receptor scintigraphy. At operation, regional or distant metastases were present in 15 (83%) and 6 (33%) patients, respectively. Eleven patients underwent potentially curative resections, and the remaining seven patients were managed palliatively by resection (four patients) or bypass procedures (three patients). Three patients had up to three more resection for metastases. Eight patients received postoperative octreotide, interferon α therapy, or both. The overall cumulative 5- and 10-year survival rates were 65.4% and 49.1%, respectively. Of the 11 patients who underwent curative resection, 10 were alive after a median follow-up of 63 months (range 7–180 months), but only 5 are free from disease. Although surgical cure is rare in nonfunctioning islet cell carcinomas, significant long-term palliation can be achieved in a large proportion of patients with an aggressive surgical approach and, when indicated, additional medical therapy.
World Journal of Surgery | 2007
Katja Schlosser; Nadine Endres; I. Celik; Volker Fendrich; M. Rothmund; E. Domínguez Fernández
BackgroundParathyroid surgery (PTX) in patients with tertiary hyperparathyroidism (tHPT) may endanger the long-term survival of transplanted renal grafts. The mechanism by which graft function deteriorates is unknown. We reviewed our experience in regard to the operative procedures and postoperative outcome.MethodsSixty-nine patients were operated on for tHPT between 1987 and 2006 at our institution. Serum (s) calcium, s-creatinine, and levels of intact parathyroid hormone (PTH) were measured before and after PTX. The Modification of Diet in Renal Disease (MDRD) equation was used to estimate glomerular filtration rate (GFR).ResultsThe entire patient group developed a deterioration of kidney graft function after PTX. Nineteen of 69 patients developed a decrease in GFR of more than 20% during the hospital stay, persisting for more than one year after PTX. Ten of them had to restart dialysis during the first year after PTX. Mean preoperative s-creatinine was 4.4 ± 0.6 mg/dl in these patients. When divided according to the surgical procedure performed, only the subgroup who underwent total parathyroidectomy showed a significant worsening of graft function when compared to subtotal or reoperative PTX.ConclusionsPTX is an efficient way to treat tHPT but represents a risk for impairing graft function, especially for patients that already demonstrate poor kidney function at the time of surgery. In the aim to prevent transient hypoparathyroidism, which may provoke reduced graft perfusion, as one possible cause of kidney graft deterioration associated with PTX, one should consider subtotal instead of total parathyroidectomy.
Molecular and Cellular Endocrinology | 2007
Sebastian Hoffmann; Andreas Rockenstein; Anette Ramaswamy; I. Celik; Anette Wunderlich; Susanne Lingelbach; Lorenz C. Hofbauer; A. Zielke
The anti-proliferative effect of retinoic acid (RA) has been documented for various tumors. Some 40% of patients with advanced and poorly differentiated thyroid cancer have been shown to respond to RA with increased uptake of radioiodine. It has been suggested that these effects may be caused by redifferentiation. Presently, little is known about the effects of RA on tumor angiogenesis, a prerequisite for growth and metastatic spread. The aim of the current study was to determine, whether tumor-induced angiogenesis of thyroid cancer is affected by RA. In vitro, the effect of 0.1/10 microM 13-cis RA on tumor cell number (MTT assay) and secretion of VEGF (ELISA) was analyzed in three thyroid cancer cell lines (FTC 236, C634 and XTC), as well as in endothelial cells (HUVEC) over several passages. In vivo, tumor growth, VEGF-expression and microvessel density (VSD) of RA treated thyroid cancer cells after xenotransplantation to nude mice was evaluated by morphometric analysis. In vitro, thyroid cancer cell lines responded to RA with reduced proliferation, ranging from 26 to 34% after 2 weeks of treatment and with up to 80% reduced secretion of VEGF. In vivo, tumor volumes of animals receiving RA were reduced by 33% (FTC 236), 27% (C643) and 6% (XTC), respectively. VSD of experimental tumors was diminished in the FTC 236 (25%) and the C643 cell line (15%), and almost unchanged in XTC tumors (7%). In vivo, VEGF-expression and apoptosis were not significantly affected by RA. In vitro, proliferation of HUVEC was inhibited by conditioned medium of C643 cells pretreated with RA (0.1/10 microM), as well as by administration of RA (0.1/10 microM). This study confirms thyroid tumor cell growth to be inhibited by RA. It demonstrates a decrease of in vitro VEGF accumulation and reduction of VSD in experimental undifferentiated thyroid carcinoma, suggesting that reduced angiogenesis may be an important mechanism responsible for the therapeutic effect of RA in thyroid cancer. Moreover, a direct anti-proliferative effect of RA on human endothelial cells is suggested.
World Journal of Surgery | 2003
Daniela Prox; Christian M. Becker; Steven R. Pirie-Shepherd; I. Celik; Judah Folkman; Oliver Kisker
Tumor growth is dependent on the balance of positive and negative regulators of angiogenesis. Antiangiogenic compounds inhibit endothelial cell biology in vitro and angiogenesis in vivo. Therefore antiangiogenic therapy presumes to be an effective treatment for pancreatic cancer. We wanted to determine the effect of antiangiogenic therapy on the growth of human pancreatic cancer in a mouse model. The angiogenesis inhibitors TNP-470 and antiangiogenic antithrombin III (aaATIII) were tested in vitro for their ability to inhibit endothelial cell proliferation. These inhibitors, along with the known antiangiogenic molecule endostatin, were then employed to treat two different primary human pancreatic cancers implanted subcutaneously into the dorsa of immunodeficient (SCID) mice. Treated tumors were examined histologically for microvessel density, apoptosis, and proliferation. All three inhibitors suppressed the growth of pancreatic tumors in vivo. Immunohistochemical analysis revealed increased degrees of apoptosis and reduced microvessel density in treated tumors compared to untreated tumors, although tumor cell proliferation was the same in both groups. None of the inhibitors tested significantly inhibited proliferation of human pancreatic cancer cells, although both TNP-470 and aaATIII were able to inhibit the proliferation of endothelial cells. The observed tumor suppression may be due to increased tumor cell apoptosis as a result of capillary dropout. These studies show that after the angiogenic switch in a human tumor, there is residual production of angiogenesis inhibitors.
British Journal of Surgery | 2003
P. Langer; Anja Wild; A. Hall; I. Celik; M. Rothmund; Detlef K. Bartsch
The appropriate treatment for a sporadic endocrine tumour may be different from those that present as part of the multiple endocrine neoplasia type 1 (MEN1) syndrome. As primary hyperparathyroidism (pHPT) and pancreaticoduodenal endocrine tumours (PETs) are the most common organ manifestations of MEN1, the prevalence of germline mutations in the MEN1 gene was determined in young patients with apparently sporadic pHPT or PETs.
Pancreatology | 2005
Iyad Hassan; I. Celik; C. Nies; A. Zielke; Berthold Gerdes; Roland Moll; Annette Ramaswamy; Hans-Joachim Wagner; Detlef K. Bartsch
The solid-pseudopapillary tumor (SPT) is a very rare pancreatic neoplasm that predominantly affects young females. About 450 cases have been described in the world literature and approximately 20% of the reported patients were children. The occurrence of SPT with distant metastases in children is extremely rare with only two previously reported cases. We now report a 16-year-old Asian girl with a large SPT and synchronous multiple liver metastases who was successfully treated in a 2-step strategy, including initial pylorus-preserving partial duodenopancreatectomy, right hemicolectomy, resection and allografting of the portal vein and secondary resection of 12 liver metastases. The patient is disease free after a follow-up of 18 months after resection of the primary tumor, suggesting that an aggressive surgical treatment might also be justified for metastasized SPT.
Chirurg | 2001
C. Nies; I. Celik; W. Lorenz; M. Koller; U. Plaul; W. Krack; H. Sitter; M. Rothmund
Abstract.Introduction: Mechanistic study endpoints, evaluated exclusively by the physician, are mostly used in clinical studies evaluating new treatment modalities (e.g. laparoscopic cholecystectomy). Those endpoints often lack clinical relevance. The patients opinion concerning the importance of a study endpoint is particularly important in the evaluation of minimally invasive procedures, which place special emphasis on patient comfort. Methods: In a first step it was evaluated by meta-analysis, which clinical endpoints have been used for comparison of laparoscopic and conventional cholecystectomy. Furthermore, using a qualitative analysis it was investigated how important the individual study endpoints are for patients and physicians. Ten patients and five surgeons were questioned in a structured interview. Results: Of all outcome variables used world-wide, approximately one third were hermeneutic study endpoints, depending on the quality of the study, but often the method of evaluation was insufficient. Only three of 215 endpoints ( < 2 %) were quality of life scores, an integrated concept of outcome was missing completely. The qualitative analysis confirms the claimed difference between isolated and integrated evaluation of treatment goals. The importance of postoperative death is underestimated by patients and physicians; postoperative pain is overestimated. Patients ranked the outcome variable “restoration of full physical fitness“ as the most important study endpoint after avoidance of complications and death. It is underestimated in isolated evaluation and has not been used in the world literature at all. Conclusion: The analysis of clinical relevance of study endpoints should be the first and not the last step of studies to evaluate surgical technology. It cannot be based purely on intuition; it must make use of scientifically accepted techniques (e.g. qualitative analysis).Zusammenfassung.Einleitung: In klinischen Studien zur Evaluation neuer Behandlungsverfahren (wie z. B. bei der Einführung der laparoskopischen Cholecystektomie) werden zumeist mechanistische, allein vom Arzt evaluierte Studienendpunkte gewählt. Häufig fehlt solchen Endpunkten die klinische Relevanz. Gerade bei der Beurteilung von minimal-invasiven Behandlungsmethoden, bei denen der Patientenkomfort im Vordergrund steht, ist die Beurteilung eines Studienendpunkts durch Patienten besonders wichtig. Methoden: Es wurde zunächst im Rahmen einer Metaanalyse evaluiert, welche klinischen Studienendpunkte beim Vergleich von laparoskopischer und konventioneller Cholecystektomie bisher verwendet wurden. Anschließend wurde mit einer qualitativen Analyse untersucht, welche Bedeutung den einzelnen Studienendpunkten von Patienten und Ärzten beigemessen wird. Hierzu wurden 10 Patienten und 5 Chirurgen in einem strukturierten Interview befragt. Ergebnisse: In Abhängigkeit von der Studienqualität wurden weltweit zu etwa einem Drittel hermeneutische Gesundheitsziele (Endpunkte) eingesetzt, aber vielfach mit ungenügender Methode. Lebensqualitätsscores wurden als 3 von 215 Endpunkten verwendet ( < 2 %), ein integratives Konzept von Outcome fehlte vollständig. Die qualitative Analyse weist den behaupteten Unterschied zwischen isolierter und integrativer Bewertung von Gesundheitszielen nach. Der postoperative Tod wurde von Patient und Arzt unterschätzt, der postoperative Schmerz überschätzt. Das von Patienten nach Vermeidung von Komplikationen und Tod am höchsten bewertete Gesundheitsziel „Wiederherstellung der vollen physischen Belastbarkeit“ wurde bei isolierter Wertung unterschätzt und tauchte in Studien der Weltliteratur überhaupt nicht auf. Schlussfolgerung: Eine Werteanalyse der klinischen Relevanz von Studienendpunkten muss an den Beginn, nicht ans Ende von Studien zur chirurgischen Technologiebewertung gestellt werden. Diese darf nicht allein aus Intuition kommen, sie muss sich heute wissenschaftlich anerkannter Methoden (z. B. qualitativer Analyse) bedienen.