Topische Therapieformen bei peripheren neuropathischen Schmerzen

The term “peripheral neuropathic pain syndromes” summarizes several chronic pain syndromes, which can occur focally or generalized in the peripheral nervous system in the course of an impairment of afferent neurons. Controlled clinical trials gave distinct indications for systemic treatments with antidepressants, anticonvulsants and opioid analgesics in several neuropathic pain syndromes. In addition to these systemic therapies, there are also two topical treatment options: topical application of lidocaine and capsaicin. An important cause of sensitization phenomena of afferent nociceptors is the upregulation of sodium channels and thermosensor channels. In the context of a partial nerve lesion that leaves behind partially preserved or regenerated afferent nerve fibres, just these channels could be used as target structures for topical medications. Topically applied drugs are absorbed systemically only in minute quantities, so systemic side effects are negligible. Pharmacological interactions with systematically acting substances are also virtually absent; thus, topically applied substances are especially appropriate for add-on therapy in addition to systemic pain medication.     

Development of a dynamic model for ventral hernia mesh repair

Introduction

The adequate way of mesh fixation in laparoscopic ventral hernia repair is still subject to debate. So far, simulation has only been carried out in a static way, thereby omitting dynamic effects of coughing or vomiting. We developed a dynamic model of the anterior abdominal wall.

Materials and methods

An aluminium cylinder was equipped with a pressure controlled, fluid-filled plastic bag, simulating the abdominal viscera. A computer-controlled system allowed the control of influx and efflux, thus creating pressure peaks of up to 200 mmHg to simulate coughing and 290 mmHg to simulate vomiting. We tested fixation with tacks (Absorbatack, Covidien Deutschland, Neustadt a. D., Germany). The model was controlled for the friction coefficient of the tissue against the mesh and the physiologic elasticity of the abdominal wall surrogate.

Results

The model was able to create pressure peaks equivalent to physiologic coughs or vomiting. Physiologic elasticity was thereby maintained. We could show that the friction coefficient is crucial to achieve a physiologic situation. The meshes showed a tendency to dislocate with an increasing number of coughs (Fig. 4). Nevertheless, when applied in a plain manner, the meshes withstood more cough cycles than when applied with a bulge as in laparoscopic surgery.

Conclusions

The dynamic movement of the abdominal wall, the friction between tissue and mesh and the way of mesh application are crucial factors that have to be controlled for in simulation of ventral abdominal hernia closure. We could demonstrate that patient specific factors such as the frequency of coughing as well as the application technique influence the long term stability of the mesh.     

Selective Surface Modification in Silicon Microfluidic Channels for Micromanipulation of Biological Macromolecules

Interactions between biological macromolecules and micrometer- and sub-micrometer-scale surface structures are directly influenced by the surface wettability, chemical reactivity and surface charge. Understanding these interactions is crucial for developing integrated microsystems for biological and biomedical processing and analysis. We report development of selective surface modification techniques based on microcontact printing and polyelectrolyte adsorption. These techniques were applied to lithographically patterned silicon microfluidic channels and flat silicon substrates to create surface microstructures with contrasting wetting properties and surface charges. These controls enabled us to devise various techniques for controlled loading and processing of biomaterials in the channels. Solutions containing long chain biological macromolecules DNA and microtubules were directly loaded into the microchannels by using a micromanipulator/microinjector system. Structural arrangements of these linear macromolecules, which were probed by using fluorescence and laser scanning confocal microscopy, were found to be quite different from bulk solutions. As expected, the filamentous molecules were observed to align linearly along the channels, with the degree of alignment dependent on channel width as well as the length of the molecule. This molecular alignment, which is induced by both the surface confinement effect and capillary flow during sample loading, may be used to enhance processing of biological materials in silicon biomedical microdevices. It also opens up the possibility of carrying out direct combinatorial structural characterization of proteins in the microchannels utilizing X-ray diffraction, which so far has not been possible.     

Lack of efficacy of high-dose intravenous immunoglobulin in autoimmune haemolytic anaemia: a clue to its mechanism*

5 patients with autoimmune haemolytic anaemia (AIHA) of warm type (4 idiopathic, 1 associated with systemic lupus erythematosus and thrombocytopenia) were treated with high doses of i.v. immunoglobulin (IgG; Sandoglobulin®; 2.0 g/kg body weight). IgG therapy was ineffective in all 5 cases as indicated by a lack of clinical improvement, continuous signs of accelerated red blood cell (RBC) destruction, and an unchanged survival rate of ⁵¹Cr-labelled autologous RBC in 4 patients studied. IgG infused at equivalent doses into 5 healthy volunteers led to an increase of IgG coating of autologous RBC (irrespective of the ABO blood groups) without concomitant changes of haemoglobin, haematocrit or reticulocytes, increase of serum IgM in 3/5, a decrease of serum C4 in 5/5, and a decrease of serum haptoglobin in 2/5 individuals. We conclude that IgG at a dose of 2.0 g/kg body weight is ineffective in AIHA. This may be caused by an increased, though clinically inapparent, interaction of IgG-coated autologous RBC with the mononuclear phagocyte system.     

High-pressure liquid chromatographic assay of folic acid: a collaborative study.

A collaborative study of the USP high-pressure liquid chromatographic assay for folic acid was performed. Two samples were analyzed in duplicate by 14 participating laboratories. Relative standard deviations for a single determination (RSDS) ranged from +/-0.40 to +/-2.39%. Based on an analysis of variance, it was concluded that the method of peak measurement was a major determinant of reproducibility and that graphical measurement was associated with a high standard deviation. Adequate resolution was obtained using a variety of columns and operating conditions. The interlaboratory RSDS was +/-1.8%.     

Studies on the platelet radioactive anti-immunoglobulin test

A platelet radioactive antiimmunoglobulin test (PRAT) has recently been introduced. In the present report, a detailed analysis of the influence of varying test conditions (i.e. effeciency of iodination of anti-IgG, cell number, degree of sensitization of platelets, times and temperatures of incubation, frequency of washings) on the results of this technique is presented. A standard procedure based on these findings is outlined. It is shown that the PRAT is two to four times more sensitive than platelet complement fixation for the detection of HLA antibodies.