Search PubMed⌕ Search

Biomedical subjects

O Seemann

Publications and source records attributed to O Seemann.

34 records · Page 2Linked to original sources
PubMed1998

Organ retrieval systems for endoscopic nephrectomy: a comparative study.

Laparoscopic or retroperitoneoscopic interventions such as nephrectomy or tumor nephrectomy call for the removal of large quantities of tissue, which can no longer be extracted via the relatively confined lumen of a cannula. For this purpose, a variety of organ retrieval systems have been designed and are commercially available with the aim of safe tissue retrieval. This paper summarizes the results of an experimental and clinical comparison of the most important organ entrapment systems suitable for endoscopic nephrectomy. The LapSacs was the first organ bag especially designed for laparoscopic nephrectomy. Despite various new modifications of this entrapment system, it still represents one of the best alternatives and has been used worldwide with success. However, because of its simplicity, it requires a certain laparoscopic expertise and involves a learning curve. Newly developed retrieval systems (i.e., LapBag, Extraction Bag, Endo-Catch) offer some advantages regarding the handling of the bag, which may be particularly useful during retroperitoneoscopic nephrectomy with a restricted working space. Retrieval systems (i.e., Endobag, Endopouch) with low resistance to tearing forces or permeability to tumor cells or bacteria (i.e., Espiner Bag) cannot be recommended for endoscopic nephrectomy.

Animals↗
PubMed1998

Laser endopyelotomy: minimally invasive therapy of ureteropelvic junction stenosis.

Endoscopic pyelotomy is a minimally invasive procedure that is increasingly used for the management of ureteropelvic junction (UPJ) obstruction. We report the results and advantages in the management of UPJ obstruction using a ureteroscopic retrograde laser-assisted approach (laser endopyelotomy; LEP). Thirty-four patients were treated between December 1994 and June 1997 by this new technique. Twenty-seven obstructions were primary. The mean time of follow-up is 18 months. An indwelling ureteral catheter was placed 3 weeks prior to treatment. Intraoperatively, after the removal of the stent, a guidewire was passed across the stenosis, and the ureter was entered with a semirigid ureteroscope. The LEP was then performed under visual control using a contact laser fiber until all obstructive fibers had been cut. Follow-up examinations included sonography, intravenous urography, and, in unclear cases, a radionuclide renal scan with furosemide application after 3 months. The success rate was 85%. The most important factor influencing the outcome was the grade of hydronephrosis. Postoperative side effects have been minimal, and minor complications occurred in only 5 patients (15%). Laser endopyelotomy is a minimally invasive procedure with less morbidity for the treatment of UPJ obstruction. Only patients with a severe extrinsic cause of obstruction should be excluded from this technique. These cases can be approached laparoscopically.

Adolescent↗
PubMed1997

[Techniques for bladder neck suspension with osseous screw fixation].

We investigated the technical feasibility and clinical results of bone fixation techniques in combination with needle suspension for correction of female stress urinary incontinence. In our experience the screw-like bone anchor, which is drilled into the public tubercle, represents a minimally invasive but very stable and reliable technique. However, the needle suspension fixed to the bone anchor turned out to be critical. Even though the suspension was fixed in the paraurethral tissue with a deep Z-stitch between the bladder neck and the midurethra, the 1-year recurrence rate was 76%. Our data showed that the suspension sutures pull through the paraurethral tissue because there is no paravesical scar formation as in open procedures. Modifications of the suspension technique (four-point suspension, simultaneous laparoscopic or digital dissection of the paravesical space, combination with sling procedures) revealed significantly improved short-term results. Therefore we conclude that after improvement of the suspension technique the bone anchor will represent a valid option for minimally invasive fixation of a bladder neck suspension.

Bone Screws↗
PubMed1997

Laparoscopy-assisted penile revascularization: a new method.

Analysis of more than 100 penile revascularizations using the Mannheim modification showed a success rate as high as 82% in properly selected patients. However, the dissection of the epigastric artery requires a relatively large incision, with the risk of postoperative bleeding, pain, and hernia formation. Therefore, we designed a laparoscopic approach for dissection of the epigastric vessels. From January 1995 to October 1996, we performed laparoscopy-assisted penile revascularization in 15 pharmacotesting nonresponders with erectile dysfunction. The first step is dissection of the penile vessels to minimize the occlusion time of the epigastric arteries. Thereafter, the extraperitoneal cavity is exposed using a balloon-trocar system inserted via a 15-mm suprapubic incision. A pneumoextraperitoneum is established, and two further cannulas are inserted (10 mm subumbilical, 5 mm in the lower abdomen contralateral to the desired epigastric artery). The dissection of the epigastric vessels starts caudally at the origin from the external iliac vessels and continues to the periumbilical area. All branches are dissected between clips, keeping the artery and vein together. For extraction of the artery, we insert another 5-mm port through the incision at the penile base. After desufflation of the extraperitoneal space and closure of the trocar wounds, microsurgical penile revascularization is performed using the previously described modification of the Hauri procedure. The mean operating time for laparoscopic dissection of epigastric artery was 120 minutes. No intraoperative complication occurred. One patient suffered from an inguinal hematoma. After a median follow-up of 12 month, 53% of patients showed spontaneous erections, and another 27% achieved a full erection with the aid of additional pharmacotherapy. Laparoscopic dissection of the epigastric arteries proved to be feasible, resulting in a considerable reduction of overall morbidity of penile revascularization without reducing the efficacy of the procedure.

Adult↗
PubMed1996

Immunochemiluminometric assay with two monoclonal antibodies against the N-terminal sequence of human parathyroid hormone.

We have developed an immunochemiluminometric assay (ICMA) with two monoclonal antibodies for the N-terminal sequence of human parathyroid hormone (hPTH). One monoclonal antibody (A1-70) was physically adsorbed onto polystyrene beads, the other (B1-70) was labelled with acridinium ester and synthetic hPTH (1-38) was used as standard. This assay has cross-reactions with synthetic hPTH (1-34) and hPTH (1-84) but no cross-reactions with hPTH (4-16), (28-48), (39-84), (44-68), (53-84) and hPTH-rP (1-86). The assay detection limit is 0.4 pmol/l. The normal range is 1.3-12 pmol/l based on 72 normal volunteers. About 91% of study patients (n = 58) with surgically proven primary hyperparathyroidism (1 degree HPT) had PTH values above normal and one of them showed a low normal intact PTH value but elevated PTH values with use of this assay. After immunoabsorption of plasma samples from patients with secondary hyperparathyroidism (2 degrees HPT) on hemodialysis with polystyrene beads containing antibodies against hPTH (39-84), some patients still showed significant amounts of PTH in this new ICMA but not intact PTH. The data reveal that significant amounts of amino-terminal immunoreactive PTH fragments rarely exist in 1 degree HPT but are present in some patients with 2 degrees HPT. The major advantage of this assay is to measure both amino-terminal PTH fragments and intact PTH with no interference from carboxy-terminal PTH fragments because two anti-N-terminal hormone sequence monoclonal antibodies are used.

Adult↗
PubMed1996

Laparoscopic retroperitoneal lymph node dissection for nonseminomatous germ cell tumors: indications and limitations.

PURPOSE: We describe our experience with laparoscopic retroperitoneal lymph node dissection in 26 patients with nonseminomatous germ cell tumors: 17 had stage I disease with no clinical (computerized tomography, ultrasound or tumor markers) evidence of metastases and 9 (2 with stage IIb and 7 with stage IIc disease) had residual tumor after chemotherapy but with negative tumor markers. Laparoscopic dissection was performed to assess more fully pathological status of the relevant retroperitoneal lymph nodes in both groups. MATERIALS AND METHODS: The patient was positioned and trocars were introduced at sites similar to that used for transperitoneal laparoscopic nephrectomy (flank position with 3, 10 mm. and 2, 5 mm. ports). After the white line of Toldt was incised and the colon was reflected anteromedially, the retroperitoneal space was exposed. The landmarks of lymph node dissection were then isolated, including the ureter, aorta, inferior vena cava and both renal veins. Lymph node dissection was performed identical to that for open surgery, with a modified template including the paracaval, interaortocaval, upper preaortic and right common iliac nodes for right tumors, and para-aortic and upper preaortic nodes for left tumors. Lymph node chains were retrieved with a small organ bag. RESULTS: The procedure was completed successfully in 16 of 17 patients with stage I disease (mean duration 268 minutes for the left and 312 minutes for the right sides). No intraoperative complications were encountered. One patient had delayed ureteral stenosis requiring operative repair, 1 had a pulmonary embolism with an uneventful outcome and 1 who underwent laparoscopic retroperitoneal lymph node dissection on the right side later had retrograde ejaculation. Embryonal carcinoma was found in 1 of the 17 patients. Average postoperative hospital stay was 4.5 days for patients without complications or conversion to an open procedure. After a median followup of 27 months no patient had regional relapse but 2 had pulmonary metastases that were treated successfully with 3 cycles of platinum based chemotherapy. Laparoscopic dissection was significantly more difficult in patients with stage II tumors after chemotherapy. Only in 2 patients with stage IIb disease was laparoscopic lymphadenectomy successful. In 5 of the 7 patients with stage IIc cancer portions of the dissection had to be done after conversion to an open (conventional) operation via a small incision (suprainguinal or pararectal). In 1 patient the laparoscopic approach was completely abandoned and converted to an open operation via a standard midline incision. In all 9 cases histopathological examination revealed complete necrosis. No patient has evidence of disease. CONCLUSIONS: Our preliminary experience suggests that a modified laparoscopic retroperitoneal lymph node dissection is feasible for stage I tumors. However, it cannot be recommended after previous chemotherapy (stages IIb and IIc disease).

Follow-Up Studies↗
PubMed1996

[Retroperitoneoscopy. Technique and experiences with the first 100 patients].

Retroperitoneoscopic procedures were already being performed in the late 1970s. The clinical breakthrough of retroperitoneoscopy, however, was initiated in 1992 by the balloon-dissecting technique of Gaur, together with the experience gained with transperitoneal laparoscopic procedures in the upper retroperitoneum. We have modified the balloon-dissecting technique into a hydraulic video-optically controlled balloon dissection of the retroperitoneal space, and this procedure was recently further simplified. From December 1992 to December 1995 we performed 100 retroperitoneoscopic procedures in 98 patients (aged 4-82 years). Twenty-two patients had undergone previous abdominal surgery, 16 patients had been operated on for kidney and ureter problems. We performed 28 simple procedures (6 renal biopsies, 17 renal cyst resections, 4 ureterocutaneostomies, 1 foreign body retrieval), 65 difficult operations (47 nephrectomies, 5 nephroureterectomies, 5 nephropexies, 4 ureterolithotomies, 2x ureterolysis). There were also 9 complicated cases (5 heminephrectomies, 2 tumor nephrectomies, 2 dismembered pyeloplasties). Operating time, complications and conversion rate to open surgery mainly depended on the difficulty of the procedure and the personal learning curve, resulting in 50-90 min, 0% and 3.8%, respectively, for an easy retroperitoneoscopy, 90-210 min, 12% and 9.2% respectively for a difficult operation, and 180-390 min, 22% and 11%, respectively, for a very difficult procedure. Excluding the 17 patients with complications or conversion (unclear anatomy, extremely difficult dissection), the mean postoperative need for analgesics was 0.7 vials, and the mean hospital stay was 4.7 days. We have now passed most of our learning curve, and retroperitoneoscopy has become a standardized procedure that is a part of the training program for the experienced urologist.

Biopsy↗
PubMed1996

[Transperitoneal and retroperitoneal laparoscopic nephrectomy in comparison with conventional nephrectomy].

We report on our clinical experience with laparoscopic nephrectomy in 35 patients. We have performed a total of 18 transperitoneal laparoscopic nephrectomies (TLN) for benign renal disease. After the introduction of a hydraulic dissecting device, we have since performed 17 retroperitoneal laparoscopic nephrectomies (RLN). These data were compared with those in 19 consecutive open nephrectomies (N). All groups were comparable in terms of indication. The mean operative time for benign disease was 206.5 min for TLN, 211.2 min for RLN and 117 min for N. Analgesic medication requirement per patient was 2 days for TLN, 1 day for RLN and 4 days for N, while the postoperative hospital stay averaged 7 days for TLN, 6 days for RLN and 10 days for N. Our results demonstrate the advantage of a laparoscopic approach over open surgery and also reveal the distinct benefit of a retroperitoneal approach. However, due to the small number of indications this procedure should be restricted to a few urologic centers.

Humans↗
PubMed1996

Retroperitoneal laparoscopic lymph node dissection for staging non-seminomatous germ cell tumors before and after chemotherapy.

We describe our experience with laparoscopic retroperitoneal lymph node dissection in 19 patients with non-seminomatous germ cell tumors. Twelve patients had stage I disease with no clinical evidence (CT-scan, ultrasound, tumor markers) of metastases; 7 patients (stage IIb=2, stage IIc=5) had residual tumor after chemotherapy but with negative tumor markers. A laparoscopic dissection was used to asses more fully the pathologic status of the relevant retroperitoneal lymph nodes of both groups. The patient was positioned and trocars introduced at sites similar to that used for transperitoneal laparoscopic nephrectomy (flank position, five ports - 3 x 10 mm; 2 x 5 mm). After reflecting the colon anteromedially, the landmarks of the lymph node dissection were isolated-namely the ureter, aorta, inferior vena cava, and both renal veins. The lymph node dissection included the paracaval, interaorto-caval, upper preaortic, and right common iliac zonal nodes for right-sided tumors, and paraaortic, upper preaortic zones for left-sided tumors. Retrieval of the lymph nodal chains was accomplished using a small organ bag. The mean duration of the procedure was 298 (range 150-405) minutes. In only one patient was a lymph node positive for tumor (stage I). Otherwise nodes showed extensive necrosis (after chemotherapy). No intraoperative complications were encountered but three patients developed a delayed complication (ureteral stenosis, pulmonary embolism, and retrograde ejaculation, respectively). Whereas we completed the dissection in each patient with stage I tumors, the laparoscopic procedure was more difficult in patients with stage II tumors after chemotherapy. In two patients with stage IIb disease laparoscopic lymphadenectomy was successful. In four other patients parts of the dissection had to be done after conversion to an open (conventional) operation using a small incision (suprainguinal or pararectal); in one patient the laparoscopic approach was abandoned and converted to an open operation. In the post-chemotherapy group the outcome depended primarily on the tumor bulk prior to drug treatment. In two patients in whom all residual necrotic tissue was removed laparoscopically they had "minor" disease (stage IIb); the others had stage IIc tumors. Our preliminary experience suggests that a modified laparoscopic lymph node dissection is feasible for stage I tumors and in selected patients with marker negative residual tumor after chemotherapy (stage IIb).

Feasibility Studies↗
PubMed1995

Establishment and characterization of a multidrug-resistant human bladder carcinoma cell line RT112/D21.

A doxorubicin-resistant human bladder carcinoma cell line RT112/D21 was established by continuous exposure of the parental line RT112 to increasing concentrations of doxorubicin over a period of 9 months. RT112/D21 cells expressed significantly more P-170 glycoprotein than the parental line, and rhodamine 123 efflux, as a functional parameter of P-170 glycoprotein activity, was increased. RT112/D21 cells were 96 times more resistant to doxorubicin than RT112 cells, and cross-resistance to epirubicin and vinblastine was present. Sensitivity to methotrexate and mitomycin C remained unchanged. R-verapamil reversed resistance to doxorubicin, epirubicin and vinblastine in RT112/D21 cells but did not affect sensitivity to methotrexate and mitomycin C. In RT112 cells, R-verapamil had no effect on drug sensitivity. Thus, it may be assumed that primary or induced MDR1 gene-encoded P-170 glycoprotein expression is a relevant mechanism of chemoresistance in transitional cell carcinoma, and that chemotherapeutic strategies in combination with chemosensitizers improve response rates.

ATP Binding Cassette Transporter, Subfamily B, Mem↗
PubMed1994

Hydrodynamic assessment of efferent limb valve mechanisms in continent urinary diversion: comparative study on a cadaveric model.

Various valve mechanisms, customarily employed in continent urinary diversion, were constructed from fresh cadaveric porcine bowel for later urodynamic assessment. A total of six different types of valves were formed from ileum or colon in varying lengths and tested by volume pressure trials. The leak point or maximum pressure were recorded at constant perfusion rates of 30 ml/min of the constructed reservoir. Ileal or colonic nipple valves, as well as the embedded or pulled-through ileum, tapered to 12 F at a length of 3 cm, withstood maximum pressures ranging between 75 and 138 cm H2O before leakage or protrusion of the valve occurred. Plicated or tapered terminal ileum in caecal reservoir revealed water leakage at pressures as low as 25 to 40 cm H2O. A newly-developed valve mechanism consisting of a 12 F, plicated colonic-serosal tunnel with a minimum intra-reservoir length of 5 cm resisted maximum pressures of more than 70 cm H2O. Our cadaveric porcine bowel model proved to be reliable for acute volume/pressure trials and correlated with all clinical urodynamic results and animal trials. It is simple, inexpensive and allows scope for individual ideas before commencing with animal trials.

Anastomosis, Surgical↗
PubMed1993

Correction of distal hypospadias: ventral adaption of the prepuce and meatal advancement.

In distal hypospadias without chordee, surgical correction has a purely cosmetic character. In contrast to standard techniques focusing on meatal position, parents often regard the redundant dorsal prepuce and its missing ventral fusion as the essential constituent of this malformation. The operative technique, presented in detail, emphasizes on foreskin reconstruction. The ventral adaption of the prepuce (VAP procedure) results in a penis with normal appearance. Complications presented reveal the importance of proper patient selection.

Child↗
PubMed1993

Comparison of urodynamic findings and response to oxybutynin in nocturnal enuresis.

Sixty-three children with persistent nocturnal enuresis were urodynamically assessed and subsequently treated with oxybutynin chloride. Urodynamic evaluation, including graduation of detrusor instability and comparison of maximum bladder capacity with the age-predicted norm, confirmed an inadequate storage function in 84% of the children. Treatment benefit totaling 70% was dependent upon urodynamic findings, with best relation to the determined bladder capacity. The value attributed to graduation of uninhibited contractions was prognostic in accordance with further subdivision of the maximum bladder capacity. Treatment benefit was limited in children with normal urodynamic findings.

Adolescent↗
PubMed1993

The effect of single shock waves on the vascular system of artificially perfused rabbit kidneys.

Extracorporeally-perfused rabbit kidneys were exposed to five shock waves at 14 kV on the XL1 Dornier experimental lithotripter (Dornier Medical Systems, Inc., Germering, Germany). While the perfusion flow rate was kept constant, the arterial perfusion pressure was recorded to assess changes in vascular resistance. Immediately after shock wave application, perfusion pressure decreased by 20%-30%, followed by a short, relative pressure rise that did not reach pretreatment values. Fifteen-twenty minutes later, arterial perfusion pressure reattained pretreatment values. Subsequent to treatment, urine flow decreased by greater than 50%. The observed pressure rise was also induced in nontreated kidneys by perfusion with the effluent of treated kidneys indicating that this is based on a humoral mechanism. On the other hand, shock wave application to formalin fixed kidneys only caused a marked decrease in arterial perfusion pressure, suggesting that this effect is due to a pure mechanical interaction of the shock wave also found with denaturated kidneys. The observed decrease of urine flow is probably caused by a decreased filtration rate. Since this was not the case in nontreated kidneys being perfused with the effluent of treated kidneys, the reduction of urine flow after extracorporeal shock wave lithotripsy does not appear to be mediated by a humoral factor, but is more likely a result of the mechanically-induced vasodilation with consecutive decline of the glomerular filtration rate.

Animals↗
PubMed1992

Penile revascularization in nonresponders to intracavernous injections using a modified microsurgical technique.

At certain centers, microsurgical penile revascularization, using different surgical techniques, has gained importance throughout the past years. In general, only patients classified as intracavernous injection nonresponders are subjected to this kind of surgery. Since 1988, revascularization surgery has been performed at our clinic on 19 intracavernous injection nonresponders. The Hauri technique was carried out on the first 6 patients. The last 10 patients underwent modified anastomosis surgery. The inferior epigastric artery and the dorsal penile artery are anastomosed, one behind the other, end-to-side, to the dorsal penile vein. This results in a more simple procedure with assurance of flow. The Virag technique was performed on 3 patients. 18 patients achieved erections with or without the aid of intracavernous injections (at a mean follow-up of 13.4 months). 11 patients were capable of spontaneous erections, whereby it was particularly noted that 8 of the 10 patients undergoing the modified technique achieved spontaneous erections. The results demonstrate that intracavernous injection nonresponders benefit from revascularization surgery.

Alprostadil↗