Peter Alken
University of Mannheim
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Featured researches published by Peter Alken.
BJUI | 2005
Mahmoud Osman; Gunnar Wendt‐Nordahl; Katrin Heger; Maurice Stephan Michel; Peter Alken; Thomas Knoll
To report our experience with over 300 patients treated with percutaneous nephrolithotomy (PNL), for although PNL was established as a treatment in the 1970s, its use diminished with the introduction of extracorporeal shockwave lithotripsy (ESWL); clinical experience with ESWL showed its limitations, and the role of PNL for treating urolithiasis was redefined, which with improvements in instruments and lithotripsy technology has expanded the capability of percutaneous stone disintegration.
BJUI | 2005
Stefan Kamp; Thomas Knoll; Mahmoud Osman; Axel Häcker; Maurice Stephan Michel; Peter Alken
Authors from Germany debate the issue as to whether the donor site for oral mucosa used in urethroplasty should be taken from the inner cheek or the lower lip, using morbidity as a deciding factor. As a result of their study they have changed their technique, now using the inner cheek as the donor site whenever possible.
Urological Research | 2006
P. Honeck; Axel Häcker; Peter Alken; Maurice Stephan Michel; Thomas Knoll
We performed a prospective, non-randomised study to determine the appropriate first-line treatment modality for distal ureteral stones. Between 2003 and 2004, a total of 124 patients with distal ureteral calculi were entered into the study (mean age 48xa0years, 35 women and 99 men). Sixty-two patients were treated with shock wave lithotripsy (SWL) and 62 patients with ureteroscopy (URS). The average stone size was 6.9xa0mm (3–33xa0mm) for SWL and 7.2xa0mm (3–30xa0mm) for URS. The treatment decision depended on the patients’ preference and clinical parameters (i.e. contraindications for anaesthesia). URS was performed under general anaesthesia, using semirigid 8xa0Fr instruments. SWL was performed under analgo-sedation using a Modulith SLX. Of patients treated with SWL, 84% had a treatment success within 7xa0days, 98% after URS. These results show a significant success (P=0.005) in favour of URS. The average in-patient stay after SWL was 3xa0days and for URS 4xa0days (not significant). The results show a high efficacy and a low complication rate for both modalities. The attained stone-free rate shows a significant advantage for primary URS.
BJUI | 2007
Daniel J. Painter; A.G. Timoney; K. Denton; Peter Alken; Francis X. Keeley
Three of the four mini‐reviews this month deal with the topic of upper tract urothelial cancer, intending to cover completely the issues of diagnosis, staging and grading, as well as surgical treatment, both open and laparoscopic. In this way the reader should be able to have at hand most of the relevant important information about the subject, all in one issue.
European Urology | 1998
Alwin Weber; Kai Uwe Koehrmann; Nicole Denig; Maurice Stephan Michel; Peter Alken
Objective: Additional anesthesia is required to minimize the tolerable pain level in efficiently performed extracorporeal shockwave lithotripsy (ESWL) with electrohydraulic and electromagnetic sources. In order to assess optimum anesthesia for each patient undergoing a standardized ESWL protocol, pain measurement and scoring were carried out. We attempted to determine the individual type and amount of analgesia prior to treatment. Methods: Patients (n = 95) with urolithiasis underwent pain measurement and scoring prior to ESWL. ‘Threshold of pain’ (TP) and ‘maximal tolerable pain (MTP) were assessed by inducing ischemia pain with the submaximum effort tourniquet technique. Pain intensity was assessed by a verbal rating scale (VRS). The results of pain measurement and amount of analgosedation were correlated in two phases. Patients were administered an oral premedication of 0.1 mg/kg midazolam. Phase 1: 60 patients were randomized into three groups: (1) piritramide (0.1–0.3 mg/kg) and midazolam (1–3 mg) i.v. (2) Lidocaine/prilocaine cream topically (30 g) to skin and diclofenac supp. 100 mg. (3) No analgesia. Phase 2: Based on the data of phase 1, cut-off points for TP and MTP were set for female and male patients. In accordance with these results, 35 patients comprised group 1 for anesthesia with piritramide/midazolam, group 2 with lidocaine/prilocaine cream and diclofenac supp. and group 3 for no analgesia at all. The electromagnetic shockwave sources Modulith SLX and Lithostar Plus were utilized. Results: Phase 1: All patients randomized for group 1 (intravenous analgosedation) were treated in accordance with the protocol. 65% of group 2 (cream/suppository) tolerated treatment as planned. 35% of patients selected for ESWL without analgesia (group 3) remained within this group. Patients requiring additional analgosedation displayed lower TP and MTP. The cut-off points for females and males were TP ≥25/35 s and MTP ≥45/60 s, respectively. Phase 2: 20/35 patients were preselected for a nonintravenous protocol. Five out of these 20 violated the protocol. The rate of additionally administered analgesia was lower than in phase 1: 35:10% in group 2 (cream/supp.), 65:40% in group 3 (no analgesia). Conclusions: The TP and MTP levels are lower in patients requiring stronger analgesia. The determined parameters are suitable for patient preselection and individual assessment of anesthesia prior to ESWL. It may be assumed that 50% of patients administered intravenous opioids are overtreated. Routine pain measurement for patient depends on the individual pain tolerance level. A third phase of this study recruiting a large number of patients will contribute to the confirmation of these results.
Urological Research | 2006
Yanwei Cao; Sreedhar Sagi; Axel Häcker; Annette Steidler; Peter Alken; Thomas Knoll
Although there is an ongoing controversy about the primary site of calcium oxalate stone (CaOx) formation, there is some evidence for extratubular crystallization. However, the mechanisms leading to such interstitial calcifications are not clear. Anatomical studies have demonstrated a close association between the renal vasculature and renal tubules. It has been hypothesized that disorders of the vasculature may contribute to renal stone formation. The exceptional papillary environment with low oxygen and high carbon dioxide is of interest in this context and its impact on CaOx toxicity to renal cells has to be evaluated. LLC-PK1, Madin-Darby canine kidney (MDCK), human umbilical vein endothelial (HUVEC) and fibroblast cell lines were exposed to hypoxia (3% O2) alone, hypercapnia combined with hypoxia (3% O2, 18% CO2) or standard culture conditions (20% O2) for 72xa0h. Cell survival rates were determined microscopically after 4xa0h of incubation with CaOx at final concentrations of 1, 2 and 4xa0mM. DAPI staining and western blot were used to evaluate the induction of apoptosis. We confirmed that CaOx leads to concentration-dependent effects on the viability of the cell lines. HUVECs were most vulnerable to CaOx among the four cell lines. Incubation under hypoxia alone had no impact on CaOx toxicity to any of the cell lines in terms of survival. However, under combined hypoxic and hypercapnic conditions, all cell lines displayed a significant reduction of cell survival compared to room air incubation. Again, this effect was most pronounced for HUVECs. The induction of apoptosis could not be demonstrated in any experimental setting. Combined hypoxia and hypercapnia clearly aggravate CaOx toxicity to renal cell lines. As we could not demonstrate the induction of apoptosis, this effect may be a result of toxic necrosis. Especially the CaOx effect on interstitial cell lines might be of interest in the chronic ischemic papillary environment. An increased toxicity may lead to recurrent stone formation, and vice versa, diseases of the vasculature, like arteriosclerosis, may further promote stone formation by induction of local ischemia. This issue has to be clarified by further studies.
World Journal of Urology | 2017
Noah Canvasser; Peter Alken; Michael E. Lipkin; Stephen Y. Nakada; Hiren S. Sodha; Abdulkadir Tepeler; Yair Lotan
The rising prevalence of kidney stone disease is associated with significant costs to healthcare systems worldwide. This is in part due to direct procedural and medical management costs, as well as indirect costs to health systems, patients, and families. A number of manuscripts evaulating the economics of stone disease have been published since the 2008s International Consultation on Stone Disease. These highlight costs associated with stone disease, including acute management, surgical management, and medical management. This work hopes to highlight optimization in care by reducing inefficient treatments and maximizing cost-efficient preventative strategies.
BJUI | 2002
Vöhringer P; T. O. Henkel; M.S. Michel; Peter Alken
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.
Urological Research | 2001
Martina Manning; Siegmar Hartmuth; W. Weidner; Peter Alken; Klaus-Peter Jünemann
Abstract From the follow-up of patients undergoing extensive testicular sperm extraction, the question of a consecutive decrease in testosterone levels arose. Further investigation was performed in the normogonad and cryptorchid Sprague-Dawley rat model. From groups A (n=40 normogonad rats) and B (n=40 cryptorchid rats), eight animals were taken and the following surgical interventions were performed: general anaesthesia (A-0, B-0), scrotal exploration (A-1, B-1), one testicular biopsy with a 2-mm tunica incision (A-2, B-2), two biopsies with a 4-mm incision (A-3, B-3), and four biopsies with a 2-mm incision (A-4, B-4). Standardised testosterone control was performed 1u2009day before as well as 1, 7 and 14u2009days after surgery. No specific testosterone reaction was found in A-0, an insignificant decrease in A-1 (3.8u2009nmol/l), a significant decrease in A-2 (6.27u2009nmol/l), in A-3 (12.96u2009nmol/l) and in A-4 (11.88u2009nmol/l). In the B rats, even in B-3 and B-4 no significant decrease was measured. The testosterone reaction correlated to the amount of tissue that was extracted, but not to the number of biopsies. The cryptorchid rats did not react in a more sensitive manner.
European Urology | 1997
M. Siegsmund; Stendler A; Kreukler C; Kai Uwe Köhrmann; Peter Alken
OBJECTIVEnWe 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.nnnMETHODSnThe 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.nnnRESULTSnAll 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.nnnCONCLUSIONnThe 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.