Biomedical subjects

K U Köhrmann

Publications and source records attributed to K U Köhrmann.

At least 19 recordsLinked to original sources

PubMed2003

[Urologic interventional therapy of kidney calculi (II)--Endoscopic methods: ureterorenoscopy and percutaneous nephrolitholapaxy].

Although ESWL allows for the treatment of most urinary stones, there are remaining situations, in which satisfying results cannot be achieved, e.g. large kidney stones or specific anatomy. In such cases endoscopic procedure like ureterorenoscopy (URS) or percutaneous nephrolithotomy (PCNL), alone or in combination with ESWL, allow minimally-invasive removal of these stones. Primarily, the development of modern intracorporeal lithotripter probes and extraction instruments along with a reduction of instruments' diameter could improve efficacy and reduce mortality. This article will provide an overview of techniques, application and results of endoscopic urinary stone treatment.

Combined Modality Therapy↗

PubMed2003

[Urologic interventional therapy of kidney calculi (I)--extracorporeal shockwave lithotripsy].

With a prevalence of around 5% in western countries, urolithiasis is a frequently occurring disease but with a poorly understood pathogenesis. Effective prevention is not possible for most stone types, in particular for calcium-containing stones, which occur most frequently. Additionally, after occurrence, patient compliance is often inadequate. Interventional therapy becomes necessary after stone manifestation within the urinary tract. Not all stone compositions respond to a drug treatment. Whereas in the seventies, stone treatment meant open surgery newly developed minimally-invasive procedures have displaced this treatment. The clinical introduction of extracorporal shock wave lithotripsy (ESWL) has played a crucial role in this process. Today, more than 80% of all urinary stones can be treated by modern lithotripters. Combination with other minimally-invasive procedures further improve stone free rate. This article provides an overview of technique, application and results of ESWL treatment.

Humans↗

PubMed2003

Rotoresect for bloodless transurethral resection of the prostate: a 4-year follow-up.

OBJECTIVE: To report the results and long-term follow-up of transurethral resection of the prostate (TURP) with a new resection device, the Rotoresect (Karl Storz, Tuttlingen, Germany). PATIENTS AND METHODS: Most endoscopic resection techniques for benign prostatic tissue aim for high ablation rates and minimal bleeding. Available resection electrodes are effective, but cause high blood loss (loop electrode), or less bleeding but poorer ablation rates (electrovaporization). To resolve these conflicts the Rotoresect was developed in 1995; it consists of a specially designed rotating resection electrode, driven by a micromotor, and a high-frequency current to enable simultaneous coagulation, vaporization and mechanical tissue removal during resection. To date, 84 patients with benign prostatic hyperplasia have had their prostate resected with this device (mean prostate size 46.0, sd 18.4 mL) and have been assessed for up to 4 years. RESULTS: During resection there was very little bleeding, with no significant changes in haemoglobin or sodium levels. The mean (sd) duration of catheterization was 1.4 (1.1) days; the urinary peak flow rate was improved from 9.7 (3.2) to 24.2 (8.23) mL/s and the residual urine volume reduced from 187.3 (109.6) to 22.7 (19.5) mL. The International Prostate Symptom Score and quality-of-life index were both improved, from 24.0 (7.5) to 4.1 (2.7), and 4.2 (3.2) to 0.8 (0.9), respectively. Overall the results were stable during the 4 years of follow-up. CONCLUSION: The Rotoresect combines the advantages of standard resection (high ablation rate) by actively rotating the resection electrode, and the haemostatic effect of electrovaporization (minimal blood loss) by simultaneous tissue coagulation and vaporization.

Aged↗

PubMed2002

Influence of the bridging effect by sequential laser application on tissue ablation in an ex vivo model, taking organ perfusion into account.

OBJECTIVE: To improve the efficacy of interstitial laser coagulation of tissue by causing a 'bridging' effect, using a sequential multiple-probe procedure on an ex vivo kidney model, as only a limited area of tissue is destroyed with a single probe and the coagulation takes longer when multiple punctures are used. MATERIALS AND METHODS: A laser beam was generated using a Nd:YAG laser and applied to kidney tissue by a diffuser tip (quartz glass cap 2 x 19 mm). For sequential laser application (SLA), three probes were placed through punctures into kidney tissue, at 5 or 10 mm apart. The laser energy was applied in different time-energy combinations through the three probes. The effect of SLA was compared with that from one probe delivering the optimal PowerMode 180 protocol (Dornier, Germering, Germany), which represents the standard energy protocol for the clinical treatment of parenchymal organs using this laser device. An isolated porcine kidney was chosen for laser coagulation under different conditions of perfusion. The ablative efficacy was defined as the volume of necrosis per minute. RESULTS: Applying various time-energy combinations to isolated unperfused porcine kidney caused extensive tissue ablation (5.6 mL). In trials with saline and blood perfusion for improved cooling, the necrotic volume was 2.5 and 3.9 mL, respectively (with no carbonization, 3.2 mL). Compared with a single-probe procedure, the ablation efficacy was 10 times better with SLA coagulation. This improvement was initiated by the bridging effect: coagulation in neighbouring areas affects perfusion and convection to an extent that induces the formation of bridges of necrosis between the probes. CONCLUSION: Tissue ablation is markedly improved by interstitial laser coagulation using a sequential multiple-probe technique.

Animals↗

PubMed2002

The URO Mentor: development and evaluation of a new computer-based interactive training system for virtual life-like simulation of diagnostic and therapeutic endourological procedures.

OBJECTIVE: To overcome the current disadvantages of traditional training methods for ureterorenoscopy and percutaneous nephrolitholapaxy, using the URO Mentor (Simbionix, Tel Aviv, Israel) computer-assisted simulator. METHODS: The URO Mentor device for training and quality control in ureterorenoscopy was developed using virtual reality, multimedia technology and intelligent tutoring systems. The central software system features a proprietary visualization engine (the SVE) which allows real-time simulation by offering a high-level object-orientated application program interface (written in C++) available for use with either Microsoft, DirectX 7 or OpenGL as platforms. The SVE includes general procedures to allow two- (2D) and three-dimensional (3D) rendering, collision detection, collision correction, 3D morphing, 2D image manipulation, texture mapping, 'bump' mapping, video texture, X-ray rendering, special effects (blood, smoke, stone fragments and more) and reflections. RESULTS: The system allows a complete training session on a wide range of procedures by offering different types of cases and virtual patients, and features a full representation of the endourological procedures under direct vision and by using interactive fluoroscopy with a contrast agent. The supported tools include: baskets, graspers, intracorporal lithotripters, guidewires, catheters, stents, biopsy and dilatation devices. The endourological procedures that can be performed are lithotripsy, tumour resection, treatment of strictures and obstructions, stent placement and biopsies. CONCLUSION: The URO Mentor introduces a new generation of mannequin equipped with a special haptic device, providing trainees with an unparalleled life-like sensation while training for diagnostic and therapeutic endourological procedures. By bringing key advances into urological simulation (e.g. with the real-time X-ray renderer) and by integrating in a single system both high-quality simulation and learning tools, the URO Mentor provides new perspectives for computer-based urological training systems and methods.

Computer Simulation↗

PubMed2002

Technical characterization of an ultrasound source for noninvasive thermoablation by high-intensity focused ultrasound.

OBJECTIVE: To develop a generator for high-intensity focused ultrasound (HIFU, a method of delivering ultrasonic energy with resultant heat and tissue destruction to a tight focus at a selected depth within the body), designed for extracorporeal coupling to allow various parenchymal organs to be treated. MATERIAL AND METHODS: The ultrasound generated by a cylindrical piezo-ceramic element is focused at a depth of 10 cm using a parabolic reflector with a diameter of 10 cm. A diagnostic B-mode ultrasonographic transducer is integrated into the source to allow the focus to be located in the target area. The field distribution of the sound pressure was measured in degassed water using a needle hydrophone. An ultrasound-force balance was used to determine the acoustic power. These measurements allowed the spatially averaged sound intensity to be calculated. The morphology and extent of tissue necrosis induced by HIFU was examined on an ex-vivo kidney model. RESULTS: The two-dimensional field distribution resulted in an approximately ellipsoidal focus of 32 x 4 mm (- 6 dB). The spatially maximum averaged sound intensity was 8591 W/cm2 at an electrical power of 400 W. The lesion caused to the ex-vivo kidney at this maximum generator power with a pulse duration of 2 s was a clearly delineated ellipsoidal coagulation necrosis up to 8.8 x 2.3 mm (length x width) and with central liquefied necrosis of 7.9 x 1.9 mm. CONCLUSION: This newly developed ultrasound generator with a focal length of 10 cm can induce clear necrosis in parenchymal tissue. Because of its specific configuration and the available power range of the ultrasound generator, there is potential for therapeutic noninvasive ablation of tissue deep within a patient's body.

Animals↗

PubMed2001

Organ sparing surgery for malignant germ cell tumor of the testis.

PURPOSE: We evaluate the indication, technique and long-term outcome of organ preserving tumor resection rather than standard orchiectomy in 73 patients with bilateral testicular germ cell tumors or tumors of a solitary testicle. MATERIALS AND METHODS: Tumor resection was performed in 73 patients with 52 and 17 metachronous and synchronous bilateral testicular germ cell tumors, respectively, and 4 testicular germ cell tumors of a solitary testicle. Histology of the enucleated germ cell tumor revealed seminoma in 42 (57.5%) patients, embryonal carcinoma in 14 (19.2%), mature teratoma in 11 (15.1%), and mixed and combined germ cell tumors in 6 (8.2%). Mean tumor diameter was 15 mm. (range 5 to 30). Associated testicular intraepithelial neoplasia was diagnosed in 82% of patients who underwent local radiation with 18 Gy. RESULTS: After a median followup of 91 months (range 3 to 191) 72 (98.6%) patients had no evidence of disease and 1 died of systemic tumor progression. No local relapse occurred in 46 patients with associated testicular intraepithelial neoplasia treated with local radiation. However, local recurrence did develop in 4 patients after 3, 6, 12 and 165 months without radiation but all survived after undergoing inguinal orchiectomy. Testosterone levels were normal in 62 (84.9%) patients, hypogonadism developed in 7 (9.6%) and preoperative levels remained low in 4 (5.5%). Of the 10 patients who postponed local radiation for paternity reasons 5 had successfully fathered a child after organ sparing surgery. CONCLUSIONS: After a long-term followup of greater than 7 years organ sparing surgery represents a viable therapeutic approach to bilateral testicular germ cell tumor with an excellent postoperative outcome. Tumor enucleation might be considered a standard approach if the guidelines are respected, including cold ischemia, organ confined tumor less than 20 mm., multiple biopsies of the tumor bed, adjuvant local irradiation postoperatively to avoid local recurrence, close followup and high compliance.

Adult↗

PubMed2001

Durability of laser probes in interstitial thermotherapy: investigations on an ex vivo model of effect of carbonization.

BACKGROUND AND PURPOSE: Interstitial laser application is successful for clinical tissue ablation in various organs. One great drawback of this method is the high costs caused by the vulnerability of the probes. Our objective was to investigate whether the prevention of carbonization deposits on laser probes averts reduced transmission after the application of high laser energy. MATERIALS AND METHODS: Interstitial laser probes were used to pierce an in vitro kidney model, and 9900 J of energy (Nd:YAG laser) was applied. The transmission of the laser probe was determined and compared with that of a reference probe. RESULTS: The application of laser energy, up to a total of 49,500 J, did not reduce transmission. The deviation of the transmission comparing working probes and the reference probe was between 2% and 7%. The application of high energy (40 W) over a longer period (>20 seconds) led to carbonization and consequent distinct reduction of transmission. CONCLUSIONS: The durability of laser probes can be prolonged by preventing carbonization. The economic effect achieved is the repeated use of the probes at less expense.

Animals↗

PubMed2001

Percutaneous nephrostomy versus ureteral stents for diversion of hydronephrosis caused by stones: a prospective, randomized clinical trial.

PURPOSE: Urinary diversion with percutaneous nephrostomy or ureteral stent is indicated by symptoms, such as persistent colic, high temperature and uremia, of hydronephrosis caused by stones. We evaluate which of these 2 methods is superior concerning the course of procedure, relief of accompanying symptoms and quality of life in regard to patient age and sex. MATERIALS AND METHODS: A total of 40 patients with stone induced hydronephrosis were randomized into either percutaneous nephrostomy or stent insertion groups. These patients were then evaluated by procedure (use of analgesics, x-ray exposure, success of insertion), relief of accompanying symptoms (duration of diversion, intravenous administration of antibiotics for high temperature) and quality of life (questionnaire immediately and 2 to 4 weeks postoperatively). RESULTS: Two comparable groups of patients were formed, with an average age of 55 versus 49 years and a male-to-female ratio of 12:8 versus 9:11 for those who underwent percutaneous nephrostomy versus those who received a stent, respectively. Percutaneous nephrostomy was successfully completed in 100% of patients and stents were successful in 80%, with a 20% conversion to percutaneous nephrostomy. The x-ray exposure was shorter in the percutaneous nephrostomy group (p = 0.052). Administration of analgesics was more frequent in the stent group (p = 0.061). Percutaneous nephrostomy indwelling time was shorter (50% less than 2 weeks) than that of stents (25% less than 2 weeks, p = 0.043). Antibiotics were administered for greater than 5 days in 0% of patients who underwent percutaneous nephrostomy versus 64% in those with stents (p = 0.174). Reduction in quality of life was moderate but more pronounced in patients with stents compared to those who underwent percutaneous nephrostomy, and was more distinct in males and younger patients. The quality of life progressively improved in the course of diversion with percutaneous nephrostomy but deteriorated with stents. CONCLUSIONS: Our results demonstrated that percutaneous nephrostomy is superior to ureteral stents for diversion of hydronephrosis caused by stones, especially in patients with a high temperature, as well as in males and juveniles.

Adult↗

PubMed2000

[Interdisciplinary consensus on diagnosis and therapy of testicular tumors. Results of an update conference based on evidence-based medicine. German Testicular Cancer study Group (GTCSG)].

BACKGROUND: An "Interdisciplinary Consensus Statement on the Diagnosis and Therapy of Testicular Tumors" was prepared in 1996 by the "Interdisciplinary Testicular Tumor Working Group" (IAH) with input from representatives from diagnostic and therapeutic disciplines of various working groups of the German Cancer Society (Strahlenther Onkol 1997;173:397-406). In 1998 the IAH met again together with the "Testicular Tumor Working Party" of the Urooncology Working Group (AUO) and formed the "German Testicular Cancer Study Group" (GTCSG). Defined and accepted interdisciplinary standards from the initial meeting were revised based on current scientific developments and clinical results. This cooperating effort increased the quality of the initial recommendations and helped to put the recommendations for diagnosing and treating testicular tumor on a broader scientific basis. METHODS: According to the principles of "evidence-based medicine" (EBM), the Consensus from 1996 was modified, based on the current level of evidence from the published literature. The methodological process and evaluation criteria used were that of the "Cochrane Collaboration". RESULTS: An "Interdisciplinary Update Consensus Statement" summarizes and defines the diagnostic and therapeutic standards according to the current scientific practices in testicular cancer. For 21 separate areas scientifically based decision criteria are suggested. For treatment areas where more than one option exist without a consensus being reached for a preferred strategy, such as in seminoma in clinical Stage I or in non-seminoma Stages CS I or CS IIA/B, all acceptable alternative strategies with their respective advantages and disadvantages are presented. This "Interdisciplinary Update Consensus" was presented at the 24th National Congress of the German Cancer Society on March 21st and subsequently evaluated and approved by the various German scientific medical societies.

Evidence-Based Medicine↗

PubMed2000

Expression of MAGE antigens and analysis of the inflammatory T-cell infiltrate in human seminoma.

The MAGE gene family encodes antigens that are recognized by cytotoxic T-cells. The expression of MAGE antigens has been linked to tumor stage, and MAGE peptides are under investigation as possible vaccines. Seminomas are tumors that are typically accompanied by a heavy inflammatory infiltrate, but have not been studied with regard to their MAGE antigen expression and its correlation with the inflammatory infiltrate. We investigated, therefore, MAGE protein expression, the amount of cytotoxic T-cells, clonality of the lymphocytic infiltrate, apoptotic activity and occurrence of necrosis. Specimens of 27 patients with classical seminoma were examined by immunohistochemistry for CD4, CD8, CD56, CD45R0, beta2-microglobulin and HLA-DR. MAGE expression was detected with the monoclonal antibody 57B, reactive with MAGE-1, -3, -4, -6 and -12. Clonality of the inflammatory infiltrate was examined by multiplex polymerase chain reaction (PCR) analysis of the T-cell receptor rearrangement. Apoptotic cells were detected by DNA nick-end labeling of fragmented DNA, and the apoptotic index was determined semi-quantitatively. Expression of 57B was found in 19 (70%) of 27 seminomas. In all cases, more than 70% of T-cells expressed CD45R0. In four cases, a predominant infiltration of CD8-positive cytotoxic T-cells (CD4/CD8 ratio < 1) was present. However, 15 seminomas showed a CD4/CD8 ratio > 1. In all cases, infiltration of CD56-positive natural killer cells was only focal. HLA-DR expression was not detectable in tumor tissue; beta2-microglobulin was only focal in three cases. Analysis of the T-cell clonality revealed a polyclonal population. The apoptotic index was not significantly different in 57B-positive seminomas (4.15%) compared with 57B negative seminomas (3.80%). Also, no correlation between the 57B expression and the occurrence of necrosis was found. MAGE antigens are homogeneously expressed in most seminomas, but their presence does not appear to represent a dominant epitope responsible for the lymphocytic infiltrate.

Adult↗

PubMed2000

Update on contact lithotripsy.

Despite the development of extracorporeal shockwave lithotripsy, endoscopic stone removal, with or without intracorporeal lithotripsy, is still an effective minimally invasive alternative for special indications. There is no defined all-purpose lithotripsy procedure for contact lithotripsy. The choice of the lithotripsy procedure for endoscopic stone disintegration depends on a number of different factors, the main one being stone localization. Small calibre, flexible probes (electrohydraulic, pneumatic, laser) are especially appropriate for ureterorenoscopy, but the speed of stone disintegration is a limiting factor. In contrast, large calibre rigid probes (ultrasound) are clearly more effective, but are unsuitable in size for flexible ureterorenoscopy. This indicates that the type and size of the endoscope decisively influences the choice of devices for endoscopic stone disintegration. Additional inhibiting factors are the flexibility or the rigidity of the instrument and the diameter of the working channel. It must be noted that total costs are not only calculated on the purchase of the equipment, but must also cover disposable materials.

Humans↗

PubMed1999

Cisplatin-resistant bladder carcinoma cells: enhanced expression of metallothioneins.

Cisplatin is one of the most potent cytotoxic drugs and in chemotherapy has ameliorated numerous tumors. Nevertheless, resistance to cisplatin is a problem that is encountered in the chemotherapy of urologic tumors, especially transitional cell carcinomas. In order to improve definition of the mechanisms of cisplatin-resistance we established a series of cisplatin-resistant sublines from the cell line RT 112 in increasing concentrations of cisplatin. The most resistant subline CP3 is approximately 10 times more resistant than the parental line and shows a 10-fold cross-resistance against methotrexate, whereas vinblastine and doxorubicin are equally effective in the parental and sublines. Combined treatment of CP3 cells with cisplatin and buthionine sulfoximine (BSO) does not result in enhanced cell kill, thereby ruling out glutathione as a resistance mechanism. However, in comparison with parental cells, CP3 cells are about 1.5 times more resistant against cadmium. On the protein level, the cisplatin-resistant cells reveal an enhanced expression of metallothionein II (MTII), but not MTI, suggesting that the cisplatin resistance we observed in these sublines is at least partly mediated by MTII. These sublines will in the future serve as valuable tools for the analysis of cisplatin resistance, especially in view of metallothionein-mediated resistance mechanisms.

Antineoplastic Agents↗

PubMed1999

Expression of the gene for the multidrug resistance-associated protein in human prostate tissue.

To characterize the clinical relevance of MRP gene in the chemoresistance of prostate carcinomas we determined the multidrug resistance-associated protein (MRP) expression in 30 samples from organ-confined prostate carcinoma, 9 samples from adjacent normal tissue and 4 hormone unresponsive cancers. The measurement of MRP expression was carried out by reverse transcription polymerase chain reaction (RT-PCR) in combination with capillary electrophoresis. Incorporated fluorescence-labeled primers were disclosed by a laser-operated fluorescence detection module. MRP expression was quantified by integration of the peak area and correlated to the ubiquitously expressed beta2 microglobulin. As positive control served the adriamycin-resistant HL60-ADR cell line, which overexpresses MRP. MRP expression was found in all samples. All samples showed a lower MRP/beta2 ratio than HL60-ADR cells. The expression of the MRP gene was 30% higher in organ-confined tumors than in hormone-unresponsive anaplastic tumors. Normal tissue showed the same MRP mRNA level as the adriamycin-sensitive HL60 cells. A higher tumor stage correlated with an increase of MRP expression (> factor 2), whereas G3 tumors displayed a MRP expression 30% lower than in G2 tumors. The small alterations indicate that MRP expression seems not be involved in the chemoresistance of prostate carcinomas.

ATP-Binding Cassette Transporters↗

PubMed1999

Interstitial laser coagulation in benign prostatic hyperplasia: A critical evaluation after 2 years of follow-Up.

Since 1993 we have prospectively followed a cumulative cohort of males with benign prostatic hyperplasia and symptomatic bladder outlet obstruction who underwent interstitial laser coagulation (ILC) of the prostate. We evaluated the safety and efficacy of ILC with respect to relief of symptoms and bladder outlet obstruction. In addition to the critical evaluation of our clinical results, the perineal and transurethral approaches were investigated as they may make a substantial impact on the overall success rate, including prostate size, number of sticks per prostate volume and type of application. A total of 59 patients were treated with the Nd-YAG laser (mediLas fibertom) between April 1993 and December 1996. At the time of reevaluation, 47 patients had completed a follow-up of up to 24 months. A perineal approach was used in 34%, transurethral in 23%, and a combined approach in 43% of the patients, depending on the preoperative volume of the prostate. 75% were high-risk patients in accordance with the ASA score (ASA III). The efficacy of treatment was assessed 6, 12, 24 and 52 weeks postoperatively in accordance with the International Prostate Symptom Score (IPS/quality of life), cystomanometric studies, peak urinary flow rate, residual volume and volume reduction of the prostate. Reduction of prostatic volume and sticks used per prostate volume were correlated to the overall success rate. A significant improvement in all voiding parameters (flow rate, residual volume), including the symptom score, was observed. P(det) decreased from an average of 90 cm H(2)O preoperatively to 42 cm H(2)O postoperatively after 24 weeks and the mean reduction in prostate volume was 14 cm(3). Interestingly, it was noted that the overall success rate was not size-related. A distinct positive correlation was found in the number of sticks performed and the improvement in objective and subjective parameters. In view of the low morbidity outcome, especially in high-risk patients, we proclaim Nd-YAG interstitial laser coagulation of the prostate to be an effective and safe alternative method of treatment for symptomatic benign prostatic hyperplasia.

Aged↗

PubMed1997

Multidrug resistance in androgen-independent growing rat prostate carcinoma cells is mediated by P-glycoprotein.

Prostate carcinomas are in general resistant against virtually all cytotoxic drugs. Up to now it has not been thoroughly evaluated whether specific resistance factors, such as the expression of the MDR1 gene, play a role in this multi-agent resistance and whether there is a link between drug resistance and hormone-independent growth. We investigated the resistance patterns of a hormone-sensitive and four hormone-independent Dunning rat carcinoma sublines against four drugs which are substrates of P-glycoprotein (vinblastine, taxol, doxorubicin, and etoposide) and two agents (methotrexate and cis-platinum) which are not transported by this efflux pump. All hormone-insensitive sublines, AT.1, AT. 3.1., MatLu and Mat LyLu, continuously showed a clearly enhanced resistance (3- to 26-fold) against the P-glycoprotein substrates, compared to the hormone-sensitive subline G. Only two of the androgen-independent sublines displayed enhanced resistance against methotrexate, whereas all of them were more sensitive against cisplatin than the androgen-sensitive G cells. By addition of verapamil the resistance against vinblastine (9- to 10-fold) and taxol (6.7- to 26.7-fold) in the hormone-insensitive cells could be almost totally reversed. Furthermore, the fluorescent P-glycoprotein substrate rhodamine-123 was effectively pumped out of the four tested hormone-independent cell lines, whereas the hormone-sensitive G cells were unable to extrude the dye. By reverse transcriptase polymerase chain reaction (RT-PCR) with primers specific for the rat mdr1b gene, the homologue to the human MDR1 gene, we could easily detect mdr1b expression in the androgen independent cell lines, but not in the G cells. Our results suggest that the product of the rat mdr1b gene is involved in the multidrug resistance of androgen-independent Dunning prostate carcinoma cells.

ATP Binding Cassette Transporter, Subfamily B, Mem↗

PubMed1997

In vitro and in vivo experiences with ureterorenoscope by Gelet.

Using ureterorenoscopes with unidirectional flow, the urologist faces a conflict between a good view on one hand and high pressure in the ureter and the pelvic collecting system of the kidney on the other hand. The ureterorenoscope designed by Gelet, which has continuous (bidirectional) flow and separate irrigation and working channels, was compared with the instrument by Pérez-Castro, which has a common irrigation and working access. The features investigated were optical quality, flow-irrigation characteristics, and handling. The latest generation of ureterorenoscopes provides small total diameters because of minimized working channels and fiberoptic image and light transmission. These semirigid instruments combine the features of flexible endoscopes and traditional ureterorenoscopes. The Gelet instrument offers continuous flow, achieved by separation of the irrigation and working channel, and provides a good view even when working instruments are inserted. The additional outlet channel prevents high pressure in the ureter and renal pelvis and offers another access for instrumentation, if necessary, which means maximum safety for the patient. Because the connection of camera and light source on a flexible system is separated from the instrument, ureterorenoscopy is a more convenient procedure for the urologist.

Fiber Optic Technology↗

PubMed1997

Enhanced in vitro cytotoxicity of idarubicin compared to epirubicin and doxorubicin in rat prostate carcinoma cells.

OBJECTIVE: We evaluated the cytotoxic activity of the three anthracyclines, doxorubicin, epirubicin and idarubicin, in different sublines of the Dunning rat prostate carcinoma as well as in multidrug-resistant KB cells, expressing a high amount of the human multidrug resistance gene product, P glycoprotein. METHODS: The effectiveness of the three anthracyclines was tested in vitro in the Dunning rat prostate carcinoma sublines G, AT.1, AT.3.1, MatLu, and MatLyLu, as well as in multidrug-resistant KB cells, using an MTT assay. RESULTS: All drugs were clearly more effective in the androgen-sensitive Dunning rat prostate carcinoma subline G than in the androgen-independent growing sublines AT.1, AT.3.1, MatLu, and MatLyLu. Idarubicin was much more effective than doxorubicin or epirubicin. To further elucidate the mechanism of action of idarubicin as compared with doxorubicin and epirubicin, we tested the cytotoxicity of these anthracyclines in highly multidrug-resistant KB-V1 cells, which express high amounts of P glycoprotein, as well as in the drug-sensitive parental KB-3-1 cells. KB-V1 cells proved to be highly resistant to doxorubicin and epirubicin with IC50 values of 2,300 and 1,000 ng/ml, respectively. Idarubicin, however, was about 57.5-fold and 25-fold more active, respectively, suggesting, that it is able to overcome P-glycoprotein-mediated multidrug resistance. CONCLUSION: The strong in vitro effectiveness of idarubicin in androgen-insensitive prostate carcinoma cells suggests that this drug might be useful in the treatment of hormone-refractory prostate carcinoma.

ATP Binding Cassette Transporter, Subfamily B, Mem↗