BACKGROUND AND OBJECTIVE:Myasthenia gravis in the majority of patients is a well treatable neurological autoimmune disorder with a prevalence of 60-150 per million. For the treatment of myasthenic crisis in the intensive care unit the use of therapeutic apheresis, e. g. immunoadsorption or plasma exchange, is well established due to its rapid therapeutic effect, whereas the necessity in long term treatment is still questioned. Aim of this retrospective cohort-study was the assessment of patients with refractory myasthenia gravis in Germany treated by regular immunoadsorption, the characterization of previous therapies and the efficacy of long-term treatment.PATIENT AND METHODS:In total 14 patients (9 women, 5 men, mean age: 40.5 years) were identified in Germany using regular therapeutic apheresis. 13 were treated with different modes of immunoadsorption (10 yen l-tryptophan-adsorption, 2 yen epitope-specific adsorption, 1 yen polyclonal sheep antibody on sepharose) and 1 with plasma exchange. Mean duration of standard treatment of myasthenia gravis before initiation of regular apheresis was 7.8 years.RESULTS:Average duration of analyzed apheresis treatment was 6.4 years, with a mean treatment-interval of 1.1 per week. Mean reduction rate of autoantibodies against acetylcholine-receptor-protein was 50-60 % per session. After initiation of immunoadsorption the mean time of hospitalisation decreased significantly by app. 60 %. In particular the number of myasthenic crises could be reduced by 89 % per year. Tolerability of immunoadsorption was very good, no severe adverse events occurred.CONCLUSION:In conclusion, for the treatment of the subgroup of myasthenia gravis patients becoming refractory to standard treatment immunoadsorption should be regarded as integral part of the therapeutic armamentarium to stabilize and optimize the state of neurologic rehabilitation. This evaluation should be also carefully considered by carriers of health care cost as currently best available evidence to decide on appropriate treatment regimens for these rare patients.

MOS capacitors and field effect transistors with arylamino-PPV as an active layer have been prepared and characterized. For this material we developed a doping method to increase the conductivity. The field effect has been demonstrated by the measurement of capacitance voltage (CV)-curves of the MOS capacitor. In accumulation the oxide capacitance is only achieved for low frequencies. At positive gate voltages inversion has not been observed. The p-doping concentrations are in the range of 1016, …, 1018 cm−3. With the realized thin film transistor structure a typical transistor behaviour has been demonstrated. The estimated value for the mobility is in the order of 10−4 cm2/Vs. This low value causes a high relaxation time. The measured characteristics of both devices show a large hysteresis for different sweep directions and a shift of the curves for repeated measurements. Mobile ions, the kinetics of incomplete ionization, chemical reactions of iodine or the polaron–bipolaron conversion might influence this behaviour. Conditions to achieve inversion were determined by two-dimensional (2-D) simulation of both devices. It turns out that, due to the low intrinsic density of organic materials, one cannot demonstrate an inversion layer in an MOS capacitor. But in the transistor structure the minority carriers are injected from source and drain into the channel generating an inversion layer. Further experimental investigations are necessary to prove this prediction and to clarify the hysteresis effect.

AIMS:The classic continuous low dose rate (LDR) brachytherapy was very important in such cases with a higher risk of severe especially late radiation reactions. From clinical experiences and radiobiological considerations it is known, that the therapeutic ratio of LDR is higher than HDR. Another way to combine the therapeutic ratio of LDR and the possibility of optimisation is the use of pulse dose rate (PDR) technique. The PDR-technique is a method, which can be compared with continuous LDR-therapy. PDR should have biological effects equivalent to conventional LDR.MATERIAL AND METHODS:We have tried to compare the classic continuous LDR-technique with 2 PDR-regimes by means of the guinea pig skin model. In this test series we involved 20 female animals with an initial weight of 400 to 500 g. We compared radiation reactions of following regimes: 1. Continuous LDR regimen with a cobalt-60 source with an activity of 5.5 mCi 30 Gy in 60 hours. 2. PDR regimen 0.5 Gy hourly, pulse length minimal 10 minutes, 30 Gy in 60 hours with an Ir-192 source with an activity of nearly 40 mCi. 3. PDR-regimen 0.8 Gy hourly with 9 hours night break (10.00 p. m. to 7.00 a. m.). The radiation reaction was controlled by the help of an evaluation table in which the criteria of radiation reaction were classified according to the degree of seriousness. The observation time is now minimal 14 and maximal 24 months.RESULTS:The findings shows a significant coincidence of early and late radiation reactions of the skin fields irradiated with the continuous LDR-technique and fields irradiated with the PDR-technique. There was not a difference of the radiation reactions between PDR-irradiation with and without night break.CONCLUSIONS:Generally it is possible to compare the radiation reactions of PDR-irradiation and the classic continuous LDR-brachytherapy. It is also possible to use a PDR-regimen with a night break of 9 hours. But results must be calculated for each tissue of interest, in our test consequently for guinea pig skin.

Since the introduction of the high-dose rate afterloading therapy a higher biological effectivity of this method has been well known in comparison with the low-dose contact therapy. This will practically taken into account by reducing the dose and more fractionating of the total dose. With our test we want: firstly to prove the influence of the therapy break on the duration of the radiation reaction. Secondly we want to prove the influence of the dose rate on the efficiency of the radiation reaction. We have tried to answer the question by the animal model guinea pig skin. We examined early reactions as well late reactions.

First results of high-dose-rate afterloading therapy in the head-neck area are encouraging. The procedure is not very invasive and is suitable especially for older patients, not tolerating much, who can be hardly submitted another therapeutic method. The limited spatial dose distribution allows a careful treatment of the surrounding tissue in spite of the application of high single doses, however limits the size of tumors too, that the afterloading therapy is possible in (max. 2 cm). The method represents an alternative of the much more complicated procedure of the low-dose contact therapy, that affects the patients in a stronger way like interstitial therapy and moulage treatment. No tumor recurrences or metastasis were seen in our patients. Influence of alteration in fractionation rhythm and of application of sources with very high dose capacity will be the subject of further studies.

In the paper surface processes are considered, i.e. sets of surfaces distributed at random in the space. For translation invariant surface processes the PALM distribution of the direction of the normal in a typical surface point is defined and related to two roses of intersection. Fibre and point processes are studied which result by intersections with planes and lines respectively. For these processes stereological formulas are proved which connect some quantities with such of the surface process. As a special ease motion invariant, i.e. translation invariant and isotropic, surface processes are treated, Furthermore, weighted surface processes are considered.