Wassilios Bentas

Goethe-Universität Frankfurt am Main, Frankfurt, Hesse, Germany

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Publications (26)75.8 Total impact

  • [Show abstract] [Hide abstract]
    ABSTRACT: To evaluate the incidence of voiding dysfunction in older male renal transplant recipients. Data for 103 patients aged 60 years or older (mean age, 65.7 years; group 1) who underwent transplantation at our center between January 1999 and August 2007 were compared with data for a group of 139 younger patients (mean age, 50.1 years; group 2) treated within the same time frame. Postoperatively, 28 group 1 recipients (27%) and 26 group 2 recipients (19%) experienced voiding dysfunction after removal of the transurethral catheter (P = .12). The most common cause was bladder outlet obstruction due to benign prostatic hyperplasia in 26 patients in group 1 (25%) and 17 patients in group 2 (12%) (P = .009). Bladder neck contracture, urethral stricture, and detrusor underactivity were diagnosed in the other patients. Transurethral resection of the prostate gland was performed in 21 group 1 patients (20%) and 14 group 2 patients (10%) (P = .02) at a mean of 31.1 and 29.5 days, respectively (P = .23) after transplantation. Surgical procedures were performed without complication, and symptoms did not recur postoperatively. Our data reveal a high incidence of voiding dysfunction in older male renal transplant recipients. High residual urine and urinary retention after renal transplantation may induce recurrent urinary tract infections, cause relevant complications, and seriously affect graft function. Recognizing the substantial effects of postoperative voiding dysfunction will enable optimum management of older kidney transplant recipients.
    Transplantation Proceedings 07/2009; 41(5):1615-8. · 0.95 Impact Factor
  • Journal of Urology - J UROL. 01/2009; 181(4):743-743.
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    ABSTRACT: Histone deacetylase (HDAC) inhibitors belong to a promising class of antineoplastic agents which affect tumor growth, differentiation and invasion. The effects of the HDAC inhibitor valproic acid (VPA) were tested in vitro on preclinical colon and pancreatic cancer models. Human colon adenocarcinoma HT-29 and pancreatic carcinoma DanG cells were treated with 1 mM VPA for different time periods during cell proliferation MTT assays, and to evaluate the tumor cell adhesion to endothelial cell monolayers. Alterations of beta1 integrin subunits alpha1-6) were analyzed by flow cytometry and RT-PCR. VPA significantly caused growth arrest in tumor cells and prevented tumor cell attachment to the endothelium. HT-29 cell adhesion was blocked to a higher extent than the adhesion of DanG cells. VPA modified membranous integrin beta1 expression, quantity and quality (up- or down-regulation) which depended on the tumor type investigated. Furthermore, VPA diminished integrin coding mRNA in HT-29 but not in DanG cells. We conclude that VPA shifts the integrin beta1 subunit balance from a 'pathological' towards a 'physiological' expression pattern leading to reduced tumor growth and invasion. Further study is required to elucidate the molecular background of the post-transcriptional modifications of VPA in order to exploit the potential of this agent in the treatment of colon and pancreatic cancer.
    International Journal of Molecular Medicine 10/2008; 22(3):293-9. · 1.96 Impact Factor
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    ABSTRACT: The purpose of this retrospective study was to evaluate the results of the Eurotransplant Senior Programme (ESP) within our centre compared to elderly recipients >or=60 years from the regular Eurotransplant Kidney Allocation System (ETKAS), specifically focusing on surgical aspects. Data from 73 ESP patients (average donor/recipient age: 71.1/67.1) were compared with those from 51 patients (49.7/63.6) treated within the framework of the ETKAS program between the years 1999 and 2006. The mean follow-up was 39.5 months. Cold ischaemic time (ESP versus ETKAS: 10.3 versus 15.0 h), duration of renal replacement therapy (42.2 versus 76.8 months), donor glomerular filtration rate (81.7 versus 109.9 ml/min/1.73 m(2)) and HLA mismatches (4.1 versus 2.4) were significantly different between the two groups (all P < 0.001). Primary graft function was seen in 74% ESP versus 69% of ETKAS patients (P > 0.05). The rate of surgical complications in the ESP versus ETKAS group was 47% versus 28% (P = 0.031) and the revision rate, 33% versus 24% (P = 0.259). Three-year patient and censored graft survival was 84% versus 92% and 85% versus 88% in the ESP and ETKAS group, respectively (all P > 0.05). Ninety-five percent of all deceased patients died with a functioning graft. The donor and recipient pool has been markedly expanded through ESP with similar patient and graft survival compared to elderly recipients grafted according to ETKAS criteria. However, patients and their physicians should be aware of the high surgical complication rate in elderly recipients, particularly when receiving elderly donor kidneys. This might seriously influence postoperative patient management but ultimately does not compromise the transplant outcome.
    Nephrology Dialysis Transplantation 07/2008; 23(6):2043-51. · 3.37 Impact Factor
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    ABSTRACT: The purpose of our study was to examine the nature and incidence of renal injuries during organ procurement, to identify risk factors and to analyse the effects of organ lesions on the following transplantation. All cadaveric kidney transplantations performed at our centre from 1996 to 2006 with an organ donated within the Eurotransplant (ET) region were retrospectively analysed. Five hundred and sixty-three renal grafts procured in 62 centres throughout the ET region were transplanted in the analysed period. One hundred and twenty (21.3%) kidneys were inadequately procured with 143 errors in total. The frequency of procurement errors did not differ significantly between kidneys procured by urologists and general surgeons (19.2% vs. 24.6%) nor when kidneys were procured alone or together with pancreas and/or liver (19.3% vs. 22.0%). Inadequate procurement lead to a discard rate of 0.2% and ultimately resulted in a surgical complication rate of 3.4%. Primary graft function (75.8% vs. 78.6%), three-yr graft survival (76.6% vs. 82.4%) and cumulated long-term graft survival were not significantly influenced by procurement errors. Additional measures to improve procurement quality are necessary. Nevertheless, adequate repair of organ lesions is possible and most organs can be successfully transplanted with very good short- and long-term results.
    Clinical Transplantation 03/2008; 22(4):411-7. · 1.63 Impact Factor
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    ABSTRACT: Organ damage during organ procurement is believed to be an increasing problem among transplant centres. However, only very few published data are available. The purpose of our study was to examine the quality of kidney procurement in Germany. We retrospectively analyzed all allograft renal transplants performed at our centre from 1996 to 2005. All kidneys were retrieved in Germany and allocated by Eurotransplant. From a total of 486 cadaveric kidneys, 103 (21.2%) were not correctly retrieved. Nevertheless, none of the organs had to be rejected. In 18 (3.7%), a technically insufficient organ retrieval was associated with a considerable extension of the surgical procedure or complications. Technically insufficient kidney procurement rarely results in clinical consequences. However, surgeons performing organ retrieval should be better trained. Whether adequate technical proficiency is achieved with ten supervised cases, as requested by the German Medical Association, remains to be determined. In our opinion, a further interdisciplinary course that trains surgeons in more refined techniques of organ procurement is desirable.
    Der Urologe 04/2007; 46(3):268-70, 271-3. · 0.46 Impact Factor
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    ABSTRACT: Organverletzungen im Rahmen der Organentnahme werden von vielen Transplantationszentren zunehmend als Problem empfunden, wobei publizierte Daten kaum vorliegen. Ziel der vorliegenden Arbeit war es, die Qualität der Leichennierenentnahme in Deutschland zu untersuchen.Alle an unserer Klinik zwischen 1996 und 2005 durchgeführten allogenen Leichennierentransplantationen mit einem innerhalb Deutschlands entnommenen und von Eurotransplant vermittelten Organ wurden retrospektiv aufgearbeitet.Von insgesamt 486 entnommenen Leichennieren wurden 103 (21,2%) von den Transplanteuren beanstandet. Keines der Organe musste abgelehnt werden. Bei 18 (3,7%) Transplantationen war die mangelhafte Entnahme mit einer erheblichen Ausweitung des Eingriffs bzw. Komplikationen verbunden.Eine mangelhafte Organentnahme geht selten mit klinischen Konsequenzen einher. Trotzdem ist eine intensivere Schulung der entnehmenden Operateure unerlässlich. Ob die von der Bundesärztekammer seit dem 01.01.2006 geforderten 10 Nierenentnahmen unter Anleitung vor selbständiger Entnahme ausreichen, bleibt abzuwarten. Eine zusätzliche klinikübergreifende Fortbildung wäre wünschenswert.
    Der Urologe 01/2007; 46(3). · 0.46 Impact Factor
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    ABSTRACT: Advanced robotic surgery was first introduced into urology in 2000. The first studies showed the feasibility and safety of the daVinci (Intuitive Surgical Inc., Sunnyvale, CA) telemanipulator assistance in radical prostatectomy, pelvi-ureteric junction obstruction, and radical cystectomy and neobladder formation. The miniature endowristed tools offer a potential advantage over standard laparoscopy in the accuracy of preparation and suturing. Other features are a three-dimensional vision system and unimpaired hand-eye coordination. Complex laparoscopic tasks are learned faster by using the robot, which may also explain the shorter training required for radical prostatectomy than for manual laparoscopy. This new and expensive technology has spread rapidly over the last 4 years. By 2004, approximately 10% of radical prostatectomies in the USA will be robot-assisted. Data on the functional and oncological outcomes are accruing but not yet conclusive. There will be a further spread of robotic surgery, routine telesurgery, smaller and more affordable systems, the introduction of virtual reality, all developments which have the potential to urological surgeons to improve.
    BJU International 12/2004; 94(8):1183-7. · 3.05 Impact Factor
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    ABSTRACT: Angiogenesis, the induction of vessel growth is involved in numerous physiological and pathological processes. While the anti-tumor effect of angiogenesis inhibitors has been extensively investigated in malignant tumors, there is very little information on the effect of angiogenesis inhibitors on inflammation induced angiogenesis. In this report, we utilized a murine model of acute chemically induced cystitis to investigate the ability of three different angiogenesis inhibitors, angiostatin, endostatin and TNP-470, to inhibit the angiogenesis stimulated by this injury. We demonstrate herein, that prophylactic application of the angiogenesis inhibitors led to a significant reduction of each of the inflammatory parameters that were measured. We conclude that anti-angiogenic therapy with angiostatin, endostatin and TNP-470 inhibits inflammation associated angiogenesis induced in this model. We also propose that anti-angiogenic agents may serve as a valuable addition to a standard cyclophosphamid chemotherapy regimen to help reduce the chemotherapy-related side effects while potentially adding an anti-tumor effect.
    Angiogenesis 02/2004; 7(1):69-73. · 4.41 Impact Factor
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    ABSTRACT: Evaluation of the diagnostic value of the combined endorectal body-phased array technique regarding the staging of prostate cancers, especially in the differentiation between stages T2 and T3. Forty-two patients with biopsy-proven or clinically suspected prostate cancer were examined on a 1.5 T scanner (Siemens, Symphony) prior to radical prostatectomy. T (2)-weighted TSE (axial, coronal) and T (2)-weighted FSE (axial) sequences were obtained with and without fat suppression. After application of 0.2 mmol/kg body-weight Gd-DTPA, T (1)-weighted GRE sequences were obtained using dynamic MRI. All images were prospectively interpreted by two observers. The MR images were correlated with the histopathological findings of wide-area sections of prostatectomy specimens. For the detection of extracapsular growth and seminal vesicle infiltration (T2 versus T3) the accuracy was between 94 % and 97 % (sensitivity 100 %, specificity between 87 % and 93 %, observer 1 and 2). In two cases with a histologically proven stadium pT2b, observer 1 had diagnosed stadium pT3a. The results of observer 2 were marginally better in only one case, which was histologically proven to be pT2b and overstaged as pT3a. MRI did not lead to under-staging of a single tumor with regard to the differentiation between T2 and T3. Overall, the staging of the tumor stages (T1 - T4) was correct in 25 of 33 cases (75 %). The dynamic MRI showed no improvement regarding sensitivity (100 %) and specificity (62 %) and achieved a staging accuracy of only 75 %. MRI performed with a combination of a pelvic phased-array coil (PPA) and integrated endorectal coil plays a significant role in the preoperative staging of prostate cancer. However, differentiation between capsular infiltration (T2) and penetration (T3) as well as evaluation of the seminal bladder (T3b) seem to be difficult.
    RöFo - Fortschritte auf dem Gebiet der R 01/2004; 175(12):1660-6. · 2.76 Impact Factor
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    ABSTRACT: To describe our technique of robotic-assisted laparoscopic radical cystectomy and intra-abdominal formation of an orthotopic neobladder (Hautmann) for treatment of transitional cell carcinoma of the bladder. We describe our surgical technique in the worldwide first attempt to perform a robotic-assisted laparoscopic radical cystectomy and completely intra-abdominal formation of an orthotopic neobladder. The DaVinci System (Intuitive Surgical, Mountain View, CA, USA) was utilized to perform the procedure. Utilizing the DaVinci System the operation could be performed without any complications. Operating time was 8.5 hours, blood loss was 200 ml. The oncologic as well as the functional result of the reservoir were excellent. We here demonstrated that sophisticated laparoscopic procedures like the intra-abdominal formation of an orthotopic neobladder are accomplishable with robotic assistance.
    European Urology 10/2003; 44(3):337-9. · 10.48 Impact Factor
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    ABSTRACT: Laparoscopic adrenalectomy is considered the standard method for removal of benign adrenal tumors, regardless of hormone activity. Minimally invasive surgery for thymomectomy aims at limited approaches, avoiding complete sternotomy or large thoracotomy. We report on a case in which totally endoscopic thymomectomy and adrenal gland resection were performed sequentially using a computer-enhanced telemanipulation system within 3 weeks. Operating time was 4.5 h for totally endoscopic adrenalectomy and 1.5 h for totally endoscopic thymomectomy. The patient was transferred to the normal ward on the day of operation after either procedure and had an uneventful recovery. Pathology yielded no malignancy in both cases. This report demonstrates the safety and feasibility of various totally endoscopic procedures performed sequentially.
    Surgical Endoscopy 10/2003; 17(9):1496. · 3.43 Impact Factor
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    ABSTRACT: In experienced hands, laparoscopic pyeloplasty is an effective alternative treatment for symptomatic ureteropelvic junction obstruction (UPJO). Although laparoscopic surgery can clearly benefit patients, laparoscopic pyeloplasty using conventional instrumentation is complex. The purpose of this report is to evaluate the feasibility of robot assisted laparoscopic surgery. Eleven pyeloplasties for UPJO were performed via a laparoscopic transperitoneal approach exclusively with the da Vinci Surgical System. The mean procedure time was 197 min (range 110-310 min). All operations were completed laparoscopically with no intraoperative complications and negligible blood loss. All patients recovered rapidly after surgery with excellent functional results at the 1 year follow-up. Our initial experience suggests that robot assisted Anderson-Hynes pyeloplasty is a safe and effective alternative to conventional laparoscopic surgery. In our opinion, robot assisted surgery will allow urologists to perform complex procedures with greater precision, confidence, and better results, as well as enable them to adapt the whole spectrum of laparoscopic procedures to their field.
    World Journal of Urology 09/2003; 21(3):133-8. · 2.89 Impact Factor
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    ABSTRACT: The robotic technique, which was first introduced in laparoscopic heart surgery, has revolutionized laparoscopic surgery over the last 5 years. In May 2000, our department accomplished the first robot assisted laparoscopic radical prostatectomy. Since that time we have performed more than 118 such procedures and several other laparoscopic operations using the robotic technique. We here summarize our experience in robot assisted laparoscopic radical prostatectomy as it has been developed over the past 3 years. Between May 2000 and May 2003, 118 patients with clinically localized prostate cancer were operated using the telerobotic da Vinci Surgical System. Operations were performed with a senior surgeon at the console, assisted by an assistant and a nurse at the operating table. Bilateral pelvic lymph node dissection was undertaken as a first step in all patients. In the initial 60 cases, we investigated different laparoscopic approaches. We used transperitoneal as well as extraperitoneal approaches. For dissection of the prostate we used ascending, descending as well as combined techniques. The combined ascending and descending technique via the transperitoneal route was chosen in 30 patients, and via the extraperitoneal route in seven patients. A modification of the descending Montsouris technique was performed in 81 patients. The robot assisted laparoscopic radical prostatectomy with the da Vinci system has been well standardized. After performing more than 100 radical prostatectomies with this system, we conclude that in our hands the Montsouris technique with only minor adoptions is the most appropriate technique for performing robot assisted radical prostatectomy.
    World Journal of Urology 09/2003; 21(3):128-32. · 2.89 Impact Factor
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    ABSTRACT: Laparoscopic radical prostatectomy is a complex procedure and has been standardized only during the last years. The remote controlled da Vinci Surgical System has opened up a new era in minimally invasive surgery. We here present our initial experience with the translation of open retropubic radical prostatectomy to laparoscopic technique using da Vinci and a one year follow-up. After a period of technical development and training on cadavers, 40 consecutive patients eligible for radical prostatectomy were treated. After port placement, the urologist took control of the 3D 30 degrees laparoscope and the two instrument arms at the da Vinci remote console to perform bilateral pelvic lymph node dissection, radical prostatovesiculectomy and urethrovesical anastomosis. The procedure was completed laparoscopically in all but two patients. Mean procedure time was 8.3 hours and mean intra-operative blood loss 570 ml. Learning curves associated with the use of the da Vinci Surgical System show that there is a 22-minute decrease in time required to perform the radical prostatectomy and lymphadenectomy for each case (p<0.0001). Patients recovered rapidly after surgery with early oncological and functional results that were similar to those obtained with our standard radical prostatectomy technique. Remote controlled robotic surgical systems are useful to translate open retropubic radical prostatectomy to laparoscopy. This new technology has the potential to equip the urologist with the microsurgical precision needed to preserve the delicate structural integrity of the pelvic floor in order to improve functional results without compromising the oncological outcome.
    European Urology 08/2003; 44(2):175-81. · 10.48 Impact Factor
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    ABSTRACT: The potential role of angiogenesis stimulators in the pathogenesis of different tumor entities has been confirmed in several studies. We measured the serum levels of basic fibroblast growth factor (bFGF), vascular endothelial growth factor (VEGF) and platelet derived growth factor (PDGF) in 51 patients with testicular germ cell tumors and in 39 healthy volunteers. Serum concentrations of bFGF, VEGF and PDGF-AB were determined by enzyme-linked immunosorbent assay. The median serum bFGF level for tumor patients was 3.46 pg/ml (range 0-61.6) compared to 0.7 pg/ml (0-11) in the control group (P<0.01). In patients with metastatic disease, the median serum bFGF level was 10.3 pg/ml (0-61.6) in contrast to 2.8 pg/ml (0-50) in patients with localized disease (P<0.01). The median serum VEGF and PDGF levels were 270 pg/ml (0-1,903) and 37,837 pg/ml (9,075-108,800), respectively, for tumor patients and 200 pg/ml (44-585) and 23,000 pg/ml (4,250-70,650) in the control group ( P<0.05). Our data suggest that angiogenesis, as reflected by serum concentrations of bFGF, VEGF and PDGF, plays a functional role in the growth and progression of testicular germ cell tumors.
    Urological Research 03/2003; 30(6):390-3. · 1.59 Impact Factor
  • European Urology Supplements - EUR UROL SUPPL. 01/2003; 2(1):63-63.
  • European Urology Supplements - EUR UROL SUPPL. 01/2003; 2(1):42-42.
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    ABSTRACT: A case of partial priapism is reported diagnosed by contrast-enhanced MR imaging and color-coded duplex sonography. Follow-up examinations after 4 weeks and 3 months were performed. According to the results of color-coded duplex sonography and MRI, a partial priapism with development from the subacute stage to a fibrous residuum after spontaneous lysis was diagnosed. There are only very few cases of partial priapism reported in the literature and this is the first case report that demonstrates diagnosis and follow-up both by color-coded duplex sonography and contrast-enhanced MR imaging.
    European Radiology 11/2002; 12(10):2532-5. · 4.34 Impact Factor
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    ABSTRACT: Prostate cancer has historically been associated with coagulation abnormalities. This study was undertaken to investigate the prevalence of abnormalities of coagulation factors in patients with prostate cancer before and after radical prostatectomy (RP). Because coagulation factors have been shown to be involved in tumor angiogenesis, the vascular density of the prostate tumors was assessed. Plasma of 40 consecutive patients with histologically proven prostate cancer was investigated pre-RP and post-RP. The antigen level for antithrombin, plasminogen activator inhibitor-1, and heparin cofactor-II, and the plasma activity of antithrombin and plasminogen were determined by using immunologic and chromogenic assays. The values of these assays were compared with a group of 28 male, age-matched patients without any evidence of cancer and 18 patients with orthopedic interventions preoperatively and postoperatively. The vascular density of the prostate tumors was assessed by staining paraffin sections with an antibody to CD34. The median plasma antigen levels and/or activities of the investigated factors were below normal in the prostate cancer patients before RP. Furthermore, coagulation factors were significantly lower than in the age-matched control group and patients before and after orthopedic surgery. In prostate cancer patients, the median values of all investigated factors went up to normal levels within 2 weeks after RP, whereas postsurgical levels in orthopedic patients remained stable. No correlations to tumor parameters have been observed. We assume that the reduction of these coagulation factors is a principle concept in prostate cancer that needs further investigation.
    The Prostate 11/2002; 53(2):160-7. · 3.84 Impact Factor

Publication Stats

489 Citations
75.80 Total Impact Points

Institutions

  • 2007–2009
    • Goethe-Universität Frankfurt am Main
      • Klinik für Urologie und Kinderurologie
      Frankfurt, Hesse, Germany
  • 2004
    • Thurgau Hospital AG
      Frauenfeld, Thurgau, Switzerland