Evaluation of the learning curve for Thulium VapoEnucleation of the prostate (ThuVEP) using a mentor-based approach.

INTRODUCTION: To evaluate the learning curve of Thulium:YAG VapoEnucleation of the prostate (ThuVEP) for patients with symptomatic benign prostatic obstruction (BPO) prospectively. METHODS: ThuVEP was performed using the 120 Watt 2 µm continuous wave Thulium:YAG laser. ThuVEP was done by a resident without experience in transurethral prostate surgery (A, n = 32), an experienced endourologist (B, n = 32), and an experienced surgeon in ThuVEP (C, n = 32), who served as the mentor for A/B. Patients were divided into consecutive subgroups of 8 patients to assess the impact of the learning curve on procedure outcome. Patient demographic, perioperative, and 12-month follow-up data were analysed. RESULTS: ThuVEP was successfully completed in all patients. Enucleation efficiency (g/min) differed significantly between surgeon A (0.48 ± 0.3), B (0.7 ± 0.36), and C (1.4 ± 0.67) (p ≤ 0.001). Enucleation efficiency correlated significantly with the weight of resected tissue in surgeon A (r = 0.88), B (r = 0.73), and C (r = 0.79) (p < 0.001). ThuVEP was performed by surgeon A and B with reasonable enucleation, morcellation, and overall operation efficiency after 8-16 procedures. At 12-month follow-up, 68 (71 %) patients were available for review. IPSS, QoL, Qmax, PVR, PSA, and prostate volume improved significantly at follow-up (p ≤ 0.023). Mean PSA/prostate volume reduction was 81.95/74.5, 80.7/79.4, and 87.6/75.9 % in surgeon A, B, and C, respectively. Urethral stricture and bladder neck contracture developed 2 (A = 1, B = 1; 2.1 %) patients and 1 (C, 1 %) patient each, respectively. CONCLUSIONS: ThuVEP can be performed with reasonable efficiency even during the initial learning course of the surgeon when closely mentored. Previous experience in the field of endourology is beneficial.

Pulse amplitude and frequency modulation of parathyroid hormone in early postmenopausal women before and on hormone replacement therapy.

Although the pathophysiology of postmenopausal osteoporosis has been investigated extensively, it is still not established in what respect PTH is related to the events. Recently, consistent data on the pulsatile secretion of PTH in man have been published. In this study intact PTH was measured in six early postmenopausal women before and after 6 months of hormone replacement therapy (HRT; 0.6 mg conjugated estrogens and 5 mg medrogestone). In addition to parameters of calcium metabolism and bone mass and to control HRT, intact PTH was measured in blood drawn over 6 h every 2 min. With HRT there was a 30% reduction in PTH secretion. Both the amount secreted per pulse (baseline, 26.8 +/- 6.9 ng/L; HRT, 21.4 +/- 7.6 ng/L; P < 0.05) as well as the basal secretion (baseline, 232.6 +/- 117.6 ng/L.h; HRT, 145.5 +/- 80.0 ng/L.h; P < 0.01) were reduced, whereas the pulse count per h remained constant (baseline, 5.1 +/- 2.2; HRT, 5.1 +/- 1.3). Power spectrum analysis showed a shift in spectral maxima consistent with these findings. Ionized and total calcium were slightly, but nonsignificantly, reduced with treatment. In summary we conclude that in early postmenopausal women, HRT reduces the secretion of PTH by reducing both the basal secretion and the amount secreted per pulse. It is conceivable that some of the known effects of HRT on bone metabolism might be mediated by the modulation of PTH secretion.

Pulse amplitude and frequency modulation of parathyroid hormone in primary hyperparathyroidism.

Pulsatile secretion of PTH in human subjects has been described recently. However, the pattern of PTH secretion in primary hyperparathyroidism (pHPT) remains to be characterized. In this study intact PTH was measured in 9 female patients with pHPT. As a control group we present data from 10 postmenopausal women. In addition to parameters of calcium metabolism and bone mass, PTH was measured in samples drawn over 4 or 6 h every 2 min by central venous blood sampling. The mean intact PTH concentration was 39.0 +/- 20.3 ng/L in healthy women and 193.2 +/- 127.9 ng/L in female patients with pHPT (P < 0.01). Pulse rhythm analysis showed significant differences between both groups for total PTH secretion per h (patients, 1196.4 +/- 485.3 ng/L; control group, 271.7 +/- 132.2 ng/L), basal PTH secretion per h (patients, 852.4 +/- 459.1 ng/L; control group, 185.6 +/- 126.1 ng/L), and average PTH secretion per pulse (patients, 112.6 +/- 54.8 ng/L; control group, 23.2 +/- 7.1 ng/L). Both patients and control subjects had, on an average, five pulses per h, and the pulsatile secretion accounted for about 50% of the total secretion. Differences in power spectrum analysis were consistent with these findings. The cross-correlation of PTH and calcium indicates an impaired feedback regulation in pHPT. PTH secretion in female patients with pHPT results from both an increased basal secretion and an increased amplitude of PTH pulses. Other features of secretion are the same as those in normal women. Feedback regulation of PTH and calcium is impaired in pHPT.

Status of the diagnostics development for the first operation phase of the stellarator Wendelstein 7-X.

An overview of the diagnostics which are essential for the first operational phase of Wendelstein 7-X and the set of diagnostics expected to be ready for operation at this time are presented. The ongoing investigations of how to cope with high levels of stray Electron Cyclotron Resonance Heating (ECRH) radiation in the ultraviolet (UV)/visible/infrared (IR) optical diagnostics are described.

Toroidal plasma rotation induced by the dynamic ergodic divertor in the TEXTOR tokamak.

The first results of the Dynamic Ergodic Divertor in TEXTOR, when operating in the m/n=3/1 mode configuration, are presented. The deeply penetrating external magnetic field perturbation of this configuration increases the toroidal plasma rotation. Staying below the excitation threshold for the m/n=2/1 tearing mode, this toroidal rotation is always in the direction of the plasma current, even if the toroidal projection of the rotating magnetic field perturbation is in the opposite direction. The observed toroidal rotation direction is consistent with a radial electric field, generated by an enhanced electron transport in the ergodic layers near the resonances of the perturbation. This is an effect different from theoretical predictions, which assume a direct coupling between rotating perturbation and plasma to be the dominant effect of momentum transfer.

Classification of dynamical diseases by new mathematical tools: application of multi-dimensional phase space analyses to the pulsatile secretion of parathyroid hormone.

The biological importance of dynamic hormonal secretion has been demonstrated. There is good evidence from recent studies that parathyroid hormone (PTH) which plays an important role in bone physiology is secreted in a pulsatile manner. In this study we performed a classification of two 'dynamical diseases' namely osteoporosis and hyperparathyroidism by the visualization of dynamic PTH-secretion in multidimensional phase spaces.