[Implementation of a scale on stone baskets]. / Implementierung einer Skala auf Steinfangkörben.

BACKGROUND: Complications after endoscopic retrieval of kidney and ureter stones are obviously related to the size of the stones as well as the experience of the surgeon and other factors. During the procedure it is sometimes difficult for surgeons to estimate stone size and therefore give prognostic advises. The visual perception of the stone size depends on the shape, colour, distance to the renoscope and dilatation of the ureter. This is the so-called binding problem, because shape, color and direction of motion are processed separately by different population of optical neurons. In order to establish a better prognostic ratio, especially for less experienced surgeons we established an intraoperative semi-quantitative measurement of the stone size supported by a stone basket. MATERIALS AND METHODS: We modified the tipped nitinol stone baskets from the company Urotech with diameters of 2.5, 3.0 and 4 Ch. The handle of this basket has a spring mechanism, which automatically closes the basket and provides a predefined fixation force of the stones within the basket. On the handle we established a non-linear scale in mm by grabbing standardized balls or standardized screws. RESULTS: The scales are nonlinear because of the nonlinear relation between the diameter of the stone and the distance of the slider. Also the scales differ in between the basket size, because of the different strain conditions due to the different wire sizes and materials or the spring and basket. CONCLUSIONS: This scale could be an important orientation for a surgeon during endourological procedures to estimate stone sizes. It could be used also for the documentation of the size of fragments after an endourologic lithotripsy and could help in the decision for or against an extraction. Finally it could be very interesting for other disciplines like gastroenterology. The scale should be validated in further clinical trials.

[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.

Monitoring training success using a lactate-speed relationship.

Monitoring training by measuring blood lactate content is a well-known procedure in sports physiology. Because of the difficulties in standardizing a test procedure in field studies, this method is fraught with considerable problems when applying it to race horses. The aim of the present study was to develop a test procedure which is able to give evidence about the training state of different race horses after nonidentical test-loads. Under almost identical environmental conditions, the level of blood lactate was determined in five trotters which were kept in training. Immediately after the single phases of a three-stage test procedure (handicap: 'small', 'medium' and 'high' load for the animals chosen at the discretion of the coach) blood samples were drawn. The lactate value was set in relation to the speed of each animal. A curve of the equation y = y0 + e(k + b*x) was fitted with r2 > 0.93 to these data. With the aid of this equation, the 'comparative speed', V, was calculated; this is the arithmetic mean of the velocities V4, V8 and V20, obtained by inserting the appropriate values for (imaginary) lactic acid concentrations in the formula. With the aid of V it was possible to detect both an increase and a decrease in physical fitness. In this way, animals tested together on one date, as well as the development of one animal tested on several dates, can be scored. Advantages and limitations of the method are discussed in detail.

Selected blood parameters during recovery from strenuous running exertion in trotters.

During training, in 10 trotters, blood samples from the vena jugularis were taken before and after a heat with 80% of maximum capability as well as in the recovery period. Lactic acid concentration and pH-value, haematocrit and haemoglobin content, as well as protein concentration and osmolality were measured. With the exception of protein concentration, the time course of the values during the recovery could be described by simple mathematical models (biexponential or exponential equations). Only in the case of blood lactate concentration, the basal value was not yet achieved 120 min after the end of exercise. In the case of the other examined parameters, the homeostasis was restored earlier. Therefore, it seems to be recommendable when performing tests with preliminary heats and finals on the same day to stick to a break of at least 2 h between two races.