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P Alken

Publications and source records attributed to P Alken.

At least 91 records · Page 5Linked to original sources
PubMed2000

[Volumetry of the urinary bladder with implantable ultrasound sensors].

Experimental studies revealed that the contractile response of the urinary bladder to sacral anterior root stimulation depends on the actual bladder volume. Furthermore, no clinical relevant technique is available for continuous monitoring of the bladder wall distension respectively bladder volume in paraplegic patients. The presented study investigates the reliability of especially developed implantable ultrasound sensors as a sensoric system for continuous monitoring of the bladder volume. In six anaesthesized pigs two ultrasound sensors, one transmitter and one receiver, were implanted on the bladder wall at different locations (latero-lateral, dorsal-ventral, rostral-caudal). After closing the abdominal wall, the bladder was filled in 50 ml steps up to 250 ml. After each filling step the running time of the ultrasound signal was measured. In all experiments reproducible results and a high correlation of the measured running times with bladder volume were observed. The latero-lateral configuration of the sensors seemed to be most confidential. The presented study indicates that bladder volumetry with implantable ultrasound sensors is possible with minimal technical prerequisites. This promising technique for continuous bladder volumetry could play an important role in the development of an intelligent and autoadaptive neurostimulator of the urinary bladder in paraplegic patients.

Animals↗
PubMed2000

Retroperitoneoscopic and laparoscopic suturing: tips and strategies for improving efficiency.

BACKGROUND: The difficulties of minimally invasive reconstructive surgery, laparoscopically or retroperitoneoscopically, are caused by spatial limitation and fixed trocar positions and, therefore, restricted movement and handling of the instruments. In addition to a standardization of the technique, continual training, and improved instrument technologies, optimization of the geometry of reconstructive surgery, such as angles and distances between the working ports or the camera and needle position, are imperative to providing an optimal clinical performance. MATERIALS AND METHODS: After designing a standardized suturing technique and conducting an experimental analysis of the geometric factors important in reconstructive surgery, we transferred these results to our clinical setting. A series of 116 reconstructive laparoscopic and retroperitoneoscopic procedures (nephropexy, pyeloplasty, bladder neck suspension, and radical prostatectomy) were analyzed according to the technical realization and quality of reconstruction. Trocar and table positions were adjusted according to our preliminary results, as were the position of the instruments and camera. RESULTS: The trocar and instrument positions are critical for the clinical outcome of reconstructive surgery. Continual training in a standardized suturing technique, together with the clinical application of the important geometric rules, can reduce surgery time by 50%. The time required for suturing single knots could be decreased even more: as much as 75%, thus ensuring efficient and safe reconstructive surgery. CONCLUSION: Reconstructive procedures such as pyeloplasty or radical prostatectomy can be standardized and performed in an acceptable amount of time with adequate quality when adhering to a standardized technique and the important geometric rules. Improved performance in terms of time and quality will increase the acceptance of these procedures, which can help to solve the problem associated with a low total number of indications for laparoscopy and retroperitoneoscopy.

Equipment Design↗
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↗
PubMed2000

Long-term experience with laparoscopic retroperitoneal lymph node dissection in the management of low-stage testis cancer.

OBJECTIVES: We describe our experience with laparoscopic retroperitoneal lymphadenectomy (LRLA) in 34 patients with low-stage germ cell tumors treated from 1992 to 1998. All patients had clinical stage-I disease with no clinical evidence (CT scan, ultrasound, tumor markers) of metastases. A laparoscopic dissection was used to assess the pathologic status of the relevant retroperitoneal lymph nodes. MATERIAL AND METHODS: 17 patients were treated by a transperitoneal laparoscopic approach, whereas in the last 17 patients retroperitoneoscopic retroperitoneal lymph node dissection was performed. The lymph node dissection was performed identically to open surgery with the modified template according to Weissbach including the paracaval, interaortocaval, upper pre-aortic, and right common iliac zonal nodes for right-sided tumors, and para-aortic, upper pre-aortic zones for left-sided tumors. Retrieval of the lymph node chains was accomplished using a small organ bag. RESULTS: The procedure could be completed successfully in 30 of 34 patients with stage-I disease. In these cases the mean duration of the procedure was 248 min. In 3 patients the lymphadenectomy was abandoned, because frozen section showed metastasis. In 1 case conversion to open surgery was necessary because of bleeding from the aorta. One patient developed a delayed ureteral stenosis which required operative repair. Three patients required temporary insertion of an indwelling ureteral stent, and another patient had a pulmonary embolism with an uneventful outcome. One patient with a LRLA on the right side later developed retrograde ejaculation. In 6 of the 33 patients (18%) embryonal carcinoma or mixed carcinoma was found. The postoperative hospital stay averaged 5.3 (3-9) days for the patients without complications or conversion to open surgery. After a median follow-up of 40 months no regional relapse occurred, but 2 patients developed pulmonary metastases which were treated successfully by three cycles of platinum-based chemotherapy. All patients have no evidence of disease. CONCLUSIONS: Our experience suggests that LRLA is a safe and accurate method for low-stage germ cell tumors with minimal invasiveness, but because of its technical difficulty it should be restricted to experienced centers.

Follow-Up Studies↗
PubMed2000

[Diagnosis and therapeutic options for prolonged erection and priapism: up-date review].

OBJECTIVE: To review the pathophysiology, diagnostic methods and treatments of priapism, with special reference to alternative treatment options. METHODS: The different surgical options are presented and discussed, with special emphasis on the oral drugs and intracavernous therapy for priapism. The advantages and inconveniences of the different agents and surgical techniques are discussed. The publications in MEDLINE 1980-2000, our experience and the results of our studies previously reported in the literature were reviewed. RESULTS/CONCLUSIONS: Complete detumescence and recovery of normal arterial blood flow can be achieved in a majority of the cases by systematic and standardized management. Sedatives, alpha-adrenergic agents or oral ketamine hydrochlorate can be utilized. However, due to the importance of the time factor, intracavernosal therapy should be the priority for persistent erection, using alpha-adrenergic agonists or other alternatives, such as methylene blue, which do not have the well-recognized risks of the conventional agents. The etiology of the priapism should be clearly established by metabolic and hemodynamic studies, since treatment will be based on the underlying disorder. In veno-occlusive low flow priapism, surgical shunting should be performed if aspiration of intracavernosal blood and other treatments are not successful. Arterial embolization and surgical ligation should be performed for high flow persistent priapism.

Humans↗
PubMed1999

Smooth muscle fatigue due to repeated urinary bladder neurostimulation: an in vivo study.

The presented study investigates the influence of different pause lengths between two consecutive stimulations of the S3 roots on intravesical pressure during bladder neurostimulation. In eight male foxhounds (aged 7-18 months), laminectomy and placement of a modified Brindley electrode were performed. In four series with different pause lengths between two consecutive stimulations (1, 3, 5, and 15 min), the maximum intravesical pressure was measured during stimulation. The changes in intravesical pressure were registered in these four series, each series with six stimulations. A 15-min interval elapsed before the commencement of each series. In the series with a pause length of 15 min, the consecutive stimulations did not result in significant changes in maximum intravesical pressure. In the 5-min series, a significant decrease in intravesical pressure was not observed after the third stimulation. In the 3-min series, a significant decrease was seen at almost every stimulation (average decrease of 3.8% per stimulation) and in the 1-min series, a significant decrease was also observed at almost every stimulation (average decrease of 5.9% per stimulation). The results of repeated bladder neurostimulation demonstrate that the maximum intravesical pressure is dependent on the pause length between two consecutive stimulations. The detrusor muscle showed reversible and short-lived signs of fatigue. This implies the importance of a minimum 5-min interval between two subsequent stimulations. A pause length <5 min leads to a falsification of the results and thus to lower validity of the investigation.

Animals↗
PubMed1999

Recording the evoked canine detrusor electromyogram.

With increasing interest in detrusor disorders and possible detrusor myopathies, a method for recording the detrusor electromyogram (detrusor-EMG) would probably greatly assist the diagnosis of various bladder dysfunctions. Therefore, we investigated the electromyographic activity of the detrusor during sacral root stimulation and during spontaneous bladder contractions in six anesthetized dogs. In all experiments, a high correlation of detrusor-EMG recordings with bladder contraction was observed. Analysis in the time domain and power spectrum analysis revealed the most clear correlation of detrusor-EMG with intravesical pressure rise in a frequency band above 3 Hz. The spike duration was 100 to 250 ms with an amplitude of 100 to 500 microV. Low-frequency activity below 1 Hz was mainly presumed to be artifacts due to fluid movement under the electrode. Our trials indicate that smooth muscle EMG recordings from the detrusor smooth musculature are possible. The exact physiological relevance of the signal in the sub-Hertz domain (<1 Hz) is still uncertain. The presented animal model allows the pathophysiologic investigation of various pathologies of bladder dysfunction and detrusor myopathies. Neurourol. Urodynam. 18:687-695, 1999.

Animals↗
PubMed1999

Restoration of bladder function in spastic neuropathic bladder using sacral deafferentation and different techniques of neurostimulation.

PURPOSE: Conventional sacral anterior root stimulation (SARS) results in simultaneous activation of both the detrusor muscle and the external urethral sphincter. We evaluated the possibilities of different neurostimulation techniques to overcome stimulation induced detrusor-sphincter-dyssynergia and to achieve a physiological voiding. MATERIAL AND METHODS: The literature was reviewed on different techniques of sacral anterior root stimulation of the bladder and the significance of posterior rhizotomy in patients with supraconal spinal cord injury suffering from the loss of voluntary bladder control, detrusor hyperreflexia and sphincter spasm. RESULTS: The achievement of selective detrusor activation would improve current sacral neurostimulation of the bladder, including the principle of "poststimulus voiding". This is possible with the application of selective neurostimulation in techniques of anodal block, high frequency block, depolarizing prepulses and cold block. Nowadays, sacral deafferentation is a standard therapy in combination with neurostimulation of the bladder because in conclusion advantages of complete rhizotomy predominate. CONCLUSIONS: The combination of sacral anterior root stimulation and sacral deafferentation is a successful procedure for restoration of bladder function in patients with supraconal spinal cord injury. Anodal block technique and cryotechnique are excellent methods for selective bladder activation to avoid detrusor-sphincter-dyssynergia and thus improve stimulation induced voiding.

Denervation↗
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

Tailored laminectomy: a new technique for neuromodulator implantation.

PURPOSE: Neuromodulation of sacral roots is an alternative mode of therapy for patients with urge incontinence or detrusor hypocontractility. We investigated the effects of sacral (S3) nerve stimulation in patients using a new surgical approach for sacral neuromodulator implantation. Modification of the implantation method with sacral laminectomy and bilateral electrode placement led to distinct improvement of stimulation, positioning and dislocation. We developed tailored laminectomy for bilateral neuromodulator electrode implantation to minimize surgical trauma. MATERIALS AND METHODS: Tailored laminectomy was performed in 6 patients with urge incontinence and 3 with a hypocontractile detrusor. After making a 10 cm. longitudinal skin incision we exposed the spinous processes of S2 and S3. Instead of complete 2-level laminectomy, only 2 oval laminectomy holes were made with a high speed ball drill. An electrode fixation hole was drilled at the edge of the laminectomy window and the wire was fixed with nonabsorbable suture material. RESULTS: In patients with idiopathic urge incontinence (followup 12.5 months, range 7 to 18) the number of leaks decreased from 7.2 to 0 daily and functional bladder capacity increased from 298 to 352 ml. In patients with a hypocontractile detrusor (followup 10.5 months, range 6 to 20) detrusor pressure increased during voiding from 12 to 34 cm. water and post-void residual decreased from 350 to 58 ml. Average surgery time was 2 hours 15 minutes. In 1 case a seroma developed near the impulse generator. CONCLUSIONS: Tailored laminectomy is a fast, minimally invasive and reliable technique for neuromodulator implantation.

Adult↗
PubMed1999

Sacral anterior root stimulation and cryotechnique: A new option for selective urethral sphincter block and reversible deafferentation in the future?

A possible application of cryotechnique might be a selective block of nerve fiber activity during sacral anterior root stimulation to achieve selective block of urethral sphincter and reversible deafferentation. In 13 foxhounds, electrical stimulation of sacral anterior roots S2 was performed while the accompanying spinal nerves were simultaneously cooled down from +25 degrees C in a stepwise fashion until a block of urethral sphincter activity was observed. The effects of cold block on the urethral sphincter and bladder were monitored by urodynamic investigation. In 2 additional dogs sacral posterior roots S2 were cooled down to +3 degrees C while accompanying anterior and posterior roots were stimulated distal to the cryothermode. Compound action potentials (APs) were registered proximal to the cryothermode before, during and after cooling and recovery time of cold blocked nerves was evaluated. Complete cold block of the urethral sphincter during spinal nerve cooling was achieved in all cases. Block temperature averaged +12 degrees C. Detrusor pressure was a mean 5,2 cm water. Recovery time was on average 5 min. The cold block was always reversible. In both dogs of the second series the compound action potentials disappeared nearly completely at +3 degrees C. Three min after the end of the cooling period the appearance of the compound action potentials was back to normal. In this study, cryotechnique proved to be effective for selective and reversible block of nerve fibers during sacral anterior root stimulation. In functional electrical stimulation this technique may lead to an improvement of quality of life in para- or tetraplegic patients resulting in optimization of voiding, standing, walking and grasping and does so without the necessity of surgical dorsal root rhizotomy.

Action Potentials↗
PubMed1999

Effects of acute urinary bladder overdistension on bladder response during sacral neurostimulation.

OBJECTIVE: Urinary retention and micturition disorders after overdistension are clinically well-known complications of subvesical obstruction. We attempted to evaluate whether bladder overdistension influences bladder response and whether overdistension supports detrusor decompensation. METHODS: Following lumbal laminectomy in 9 male foxhounds, the sacral anterior roots S2 and S3 were placed into a modified Brindley electrode for reproducible and controlled detrusor activation. The bladder was filled in stages of 50 ml from 0 to 700 ml, corresponding to an overdistension. At each volume, the bladder response during sacral anterior root stimulation was registered. After overdistension, the bladder was refilled stepwise from 0 to 300 ml and stimulated. RESULTS: In all dogs, the bladder response was influenced by the intravesical volume. The maximum pressure (mean 69.1 cm H(2)O) was observed at mean volume of 100 ml. During overdistension, a significant reduction in bladder response of more than 80% was seen. After overdistension, a significant reduction in intravesical pressure of 19.0% was observed. In 2 cases, reduction in bladder response was more than 50% after a single overdistension. CONCLUSIONS: We conclude that motoric bladder function is influenced during and after overdistension. A single bladder overdistension can support acute and long-lasting detrusor decompensation. In order to protect motoric bladder function, bladder overdistension must be prevented.

Animals↗
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↗
PubMed1999

Extradural cold block for selective neurostimulation of the bladder: development of a new technique.

PURPOSE: Cryotechnique for selective block of the urethral sphincter and simultaneous activation of the bladder was developed to achieve physiological micturition during sacral anterior root stimulation (SARS). MATERIALS AND METHODS: In ten foxhounds SARS of S2 was carried out while extradurally both spinal nerves S2 were cooled down from positive 25C in a stepwise fashion until a sphincter block was observed. Subsequently, SARS of S2 was performed while the pudendal nerves were cooled down from + 15C. The effects of spinal and pudendal nerve cold block on the urethral sphincter and bladder during SARS and the recovery time were monitored by urodynamic investigation. RESULTS: A complete cold block of the urethral sphincter during spinal nerve cooling was achieved in all cases. During pudendal nerve cooling, the sphincter was completely blocked in two, and incompletely blocked in four dogs. Cold block temperature of the spinal nerves averaged +11.7C and of the pudendal nerves +6.2C. During SARS and spinal nerve cooling, an increase in intravesical pressure up to 13 cm. water was recognized, and recovery time was on average 6.6 minutes. Intravesical pressure remained unchanged during pudendal nerve cooling, with recovery time being less than 1 minute. The cold block was always reversible. CONCLUSIONS: Cryotechnique is an excellent method for selective and reversible block of the urethral sphincter during SARS to avoid detrusor-sphincter-dyssynergia. The application of cryotechnique in functional electrical stimulation leads to an improvement of quality of life in para- or tetraplegic patients because of selective nerve stimulation with optimization of micturition, standing, walking and grasping and does so without the necessity of surgical dorsal root rhizotomy.

Animals↗