[Coating with plasma-deposited functionalized diamond-like carbon to decrease encrustations on urological implants]. / Plasmadeponierte funktionalisierte Kohlenstoffschichten zur Minderung von Inkrustationen auf urologischen Implantaten.

The double-J stents used today for palliative artificial urinary diversion very often show extreme formation of encrustations, even a short time after implantation. Despite increased scientific material development, the complication rate has not really been strongly influenced. Grant-aided by the German Federal Ministry of Education and Research, we chose a new interdisciplinary and translational approach by coating standard stent materials with plasma-deposited amorphous diamond-like carbon. These stents show clearly reduced rates of encrustation in vitro. Ongoing clinical trials demonstrate a further enhancement of this effect in vivo. The underlying mechanisms are being investigated by extending the established in vitro model, thereby pushing research in this field to a new level.

[Extended metabolic diagnosis of urolithiasis]. / Erweiterte metabolische Diagnostik des Harnsteinleidens.

PURPOSE: In Germany, urolithiasis, with a frequency of 5 % and a continuously increasing incidence, must be considered as a widespread disease. Ever growing socio-economic expenses have become the focus of attention. The present treatment strategies provide only limited support for the practitioner in evaluating the often complex causes of urolithiasis and in assessing the chosen treatment. A successful treatment with minimal effort requires a general improvement of existing options in prophylaxis as well as metaphylaxis of urolithiasis. For this purpose, detailed examination and interpretation of a stone-former's urinary composition are essential. MATERIAL AND METHODS: The following two novel and significant methods with rapid and uncomplicated application procedures are presented: 1) The easy-to-perform and accurate determination of the calcium oxalate crystallisation risk from a urine sample using the BONN risk index (BRI) for the most frequently occurring stone type (75 %). 2) Consideration of the chemical depletion of lithogenic components in a urine sample due to in-vivo growing uroliths. This phenomenon, the so-called depletion effect, can be of considerable clinical relevance due to possible determination of false normal urinary parameters. RESULTS: This review article explains the theoretical background of these methods and the many applications of the novel methods in practice. CONCLUSIONS: New strategies in stone prevention can help to reduce the extent of urolithiasis in a patient. The BRI enables the practitioner to optimise patient treatment without major effort. Consideration of the stone growth-related alteration of composition improves the interpretation of urine analysis.

[Plasma-deposited carbon coating on urological indwelling catheters: Preventing formation of encrustations and consecutive complications]. / Plasmadeponierte Kohlenstoffbeschichtung auf urologischen Verweilkathetern: Vermeidung der Ausbildung von Inkrustationen und konsekutiven Komplikationen.

BACKGROUND: Any material placed in the urinary tract is susceptible to the formation of encrustations of crystalline bacterial biofilms. These biofilms cause severe complications in some cases. The strategies used so far for reduction of these complications by surface modifications of the implant material failed to show the expected results. PATIENTS AND METHODS: In this study, we investigated amorphous carbon coatings (a-C:H) for their ability to effectively reduce or to repress the progressive formation of infection-enhancing crystalline biofilms as new functional surface coatings. In nine patients suffering for several years from stenting, a-C:H-coated ureteral stents were tested in treatment attempts. The current replacement intervals amounted to a mean of 77 days; the principle cause for early replacement was massive stent encrustations associated with symptomatic urinary tract infections. RESULTS: In total, 20 coated ureteral stents were tested spanning indwelling times between 3 and 4 months. No stent-related complications occurred. In all cases extraordinarily facile handling, less pain during replacement, and markedly increased tolerance were observed. Symptomatic urinary tract infections were reduced by more than 50%. The stents remained virtually free of encrustations. CONCLUSION: a-C:H coatings are a novel strategy leading to an enhancement of long-term applicability of ureteral stents and catheters and to improved patient comfort.