The Functional Consequences of the CTNS-deletion for the TRPV1-receptor in Cystinosis Patients

"During the study period (Day 1), in each subject 3 equally spaced (minimum distance of 4 cm) 10-mm rubber O-rings (8 mm inner diameter) will be placed on the volar surface of the forearm. The most proximal ring (i.e. at least 15 cm proximal of the wrist crease) is referred to as ring number 1; the most distal ring is referred to as ring number 3; in between is ring number 2.~In ring number 1 and 2, subjects will receive a topical dose of 1000 µg/20 µL capsaicin (single-blind). Change in dermal blood flow induced by capsaicin will be measured with Laser Doppler Imaging."

"During the study period (Day 1), in each subject 3 equally spaced (minimum distance of 4 cm) 10-mm rubber O-rings (8 mm inner diameter) will be placed on the volar surface of the forearm. The most proximal ring (i.e. at least 15 cm proximal of the wrist crease) is referred to as ring number 1; the most distal ring is referred to as ring number 3; in between is ring number 2.~In ring number 3, subjects will receive a topical dose of placebo (single-blind).Change in dermal blood flow induced by placebo will be measured with Laser Doppler Imaging."

Von Frey filaments will be used to measured the mechanical detection and pain threshold of the volunteers. The Von Frey filaments will be applied on the upper capsaicin spot in sequential order. The subject will be asked to indicate when he feels the application of the Von Frey filaments and when it hurts.

Temperature sensitivity (detection and pain threshold) will be determined using Advanced Thermal stimulation. A thermode will be attached to the hand of the volunteer with a baseline temperature of 32°C. The thermode will heat up and cool down with a rate of 1°C/second and the volunteer will be asked to click on a computer mouse when he feels the change in temperature and when it hurts.