[Menthol in the adjuvant treatment of gallbladder stones fragmented by ESWL as an option for reducing doses of urso- and chenodeoxycholic acid]. / Mentholsubstitution als Option zur Dosisreduktion von Urso- und Chenodeoxycholsäure in der adjuvanten Therapie nach ESWL von Gallenblasensteinen.

BACKGROUND: Assessments of the litholytic activity of terpenes in the conservative treatment of gallstone disease vary. Achievement of a stone-free state through dissolution of residual fragments after extracorporeal shock wave lithotripsy (ESWL) is a suitable model for investigating the litholytic activity of menthol. PATIENTS AND METHODS: After ESWL in patients with symptomatic gallbladder stones, the litholytic efficacy of the standard therapy of 125 mg urso-/chenodeoxycholic acid (UDC/CDC) per 25 kg body weight (UDC + CDC) was compared with that of 62.5 mg UDC/CDC plus 125 mg menthol (M) per 25 kg body weight (M + UDC + CDC). 70 patients were treated with M + UDC + CDC (n = 36) or UDC + CDC (n = 34) in a double-blind design. RESULTS: 19 of 34 patients (55.9%) in the UDC + CDC group became stonefree in an average period of 5.9 months, compared with 17 out of 36 patients (47.2%) in the M + UDC + CDC group in 8.8 months. Although the patients on UDC + CDC became stone-free significantly more quickly (p = max [p1,p2] = 0.4717), there was no relevant statistical difference in the total number of stone-free patients between the two treatment groups. After subtraction of the patients who terminated the study prematurely, significantly larger numbers of stone-free patients under the standard therapy were found at 9 and 12 months (16 : 9 and 19 : 12, respectively), while at the other time points no significant difference was found. Before ESWL, seven of 25 patients in the menthol group had two or more stones, while in the group treated with the standard therapy this was only the case in two patients. Five patients had mild calcification on admission to the study, four of whom received M + UDC + CDC. CONCLUSION: Overall, patients become stone-free more quickly on the standard UDC + CDC therapy. However, after subtraction of the patients who discontinued the study prematurely it can be seen that this results from significantly higher numbers of stone-free patients at 9 and 12 months, so that over the entire observation period-and in consideration of the less favorable stone parameters in the menthol group-there is no substantial statistically relevant difference in the efficacy of the two treatments.

Fabrication of gap-optimized CMUT.

A recently introduced set up of capacitive micromachined ultrasonic transducers (cMUT) combines a conductive membrane above a structured sacrificial layer. All previous approaches either require an additional metallic electrode or do not possess a structured sacrificial layer and, consequently, may make exact adjustment of the membrane dimensions difficult. The present set ups are especially suited for the fabrication of cMUT with gap heights ranging between 50 nm and 2 microm between the electrodes. Large gaps are a prerequisite to enabling sufficient deflections of the membrane and, therewith, to generating high pressure gradients. On the other hand, small gap sizes are desirable for detecting weak ultrasonic sources. This paper focuses on the fabrication process of cMUT to realize electrode separation above 500 nm and, in addition, on the manufacturing of cMUT with gaps below 500 nm. The successful realization has been proven by some basic experimental investigations. Finally, the fundamental equations of a frequently chosen simulation model are documented, as a number of ambiguities exist in the common literature.