Chorologische phänomene in Wasserpflanzengesellschaften Mitteleuropas

On the basis of three selected examples chorological phenomena in waterplant communities of central, east and southern Europe are represented. Species of the Atlantic-oceanic floral element of the order Juncetalia bulbosi, like Pilularia globulifera, Eleocharis multicaulis and Deschampsia setacea are growing in markedly secondary sites near their eastern border, i.e. in the Lusatian district of central Europe, especially in sand, gravel and clay pits as well as in residue lakes of opencast mines. As a result of intensive recent human activities numerous new sites are being established now causing an expansion of their distribution area. With decreasing oceanity from the central part to the eastern border of the area a change in the floristic-sociological structure of the relevant plant communities and in the hydrochemical composition of the respective water bodies takes place. In western Europe the species grow in soft water poor in minerals, in the eastern part (central Europe) in mineral-rich, hard water with calcium and sulphate.At present Ceratophyllum submersum has a high frequency in the northeastern area in Mecklenburg. The sites are morainic lakes (kettle holes) and small waters and ponds near settlements, which are enriched in minerals and nitrales in consequence of the intensive agricultural use of inorganic fertilizers. Moreover the waters are alkaline and rich in minerals, especially bicarbonate and possess a high range of total hardness. The example of eight different sites of Aldrovanda vesiculosa illustrates a striking change of its diagnostic value in its disjunct north-south distribution. In the northern part of central Europe Aldrovanda is found in the communities of the Utricularietea intermedio-minoris, both in waters with a low acidity rich in sulphate and in alkaline waters rich in bicarbonate (Sphagno-Utricularion and Scorpidio-Utricularion respectively). In southern central Europe and in southeastern Europe Aldrovanda occurs in Lemnetea and Potametea communities. In northeastern Poland Aldrovanda is found together with Hydrilla verticillata, Chara mentosa, Myriophyllum verticillatum and Scorpidium scorpioides.

Die Sippennomenklatur richtet sich nach Rothmaler et al. (1970).     

The FDA approved PI3K inhibitor GDC‐0941 enhances in vitro the anti‐neoplastic efficacy of Axitinib against c‐myc‐amplified high‐risk medulloblastoma

Aberrant receptor kinase signalling and tumour neovascularization are hallmarks of medulloblastoma development and are both considered valuable therapeutic targets. In addition to VEGFR1/2, expression of PDGFR α/β in particular has been documented as characteristic of metastatic disease correlating with poor prognosis. Therefore, we have been suggested that the clinically approved multi‐kinase angiogenesis inhibitor Axitinib, which specifically targets these kinases, might constitute a promising option for medulloblastoma treatment. Indeed, our results delineate anti‐neoplastic activity of Axitinib in medulloblastoma cell lines modelling the most aggressive c‐myc‐amplified Non‐WNT/Non‐SHH and SHH‐TP53‐mutated tumours. Exposure of medulloblastoma cell lines to Axitinib results in marked inhibition of proliferation and profound induction of cell death. The differential efficacy of Axitinib is in line with target expression of medulloblastoma cells identifying VEGFR 1/2, PDGFR α/β and c‐kit as potential markers for drug application. The high specificity of Axitinib and the consequential low impact on the haematopoietic and immune system render this drug ideal multi‐modal treatment approaches. In this context, we demonstrate that the clinically available PI3K inhibitor GDC‐0941 enhances the anti‐neoplastic efficacy of Axitinib against c‐myc‐amplified medulloblastoma. Our findings provide a rational to further evaluate Axitinib alone and in combination with other therapeutic agents for the treatment of most aggressive medulloblastoma subtypes.     

The Factor Inhibiting HIF Asparaginyl Hydroxylase Regulates Oxidative Metabolism and Accelerates Metabolic Adaptation to Hypoxia

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Critical evaluation of indications for the holmium:YAG laser and the neodymium:YAG laser in orthopedic surgery based on an in vitro study]

This is an in vitro study of the biophysical effects of holmium:YAG and neodymium-YAG lasers that was prompted by the poor clinical results obtained with lumbar percutaneous laser discus decompression (PLDD). In the absence of adequate cooling, ablation of tissue with the holmium:YAG laser causes thermal damage to the surrounding tissues. Utilizing the immediate colour-independent laser coupling effect, the holmium:YAG laser removes soft and hard tissue immediately. The low tissue penetrating power (max. 0.32 mm), together with the use of irrigation, avoids thermal problems, and this laser type with its high pulse energy and frequency is to be recommended for arthroscopic surgery. In contrast, the effects of the neodymium:YAG laser are highly dependent on tissue colour. Using this laser on light-coloured tissue only diffuse warming but no ablation of soft tissue was often seen. The depth of tissue penetration seen in our study was 0.58 mm, but is greatly dependent on the duration of application, and is much larger with long application times. In conclusion, we believe that the neodymium:YAG laser is more suitable for percutaneous intradiscal procedures than the holmium:YAG laser. For arthroscopic surgery, the holmium:YAG laser will be the better choice. The effect of each type of laser depends not only on its physical properties, but also on tissue properties (light or dark-coloured, thermal conductivity) and duration of application.     

Respiratory phase detection and delay determination for breath-by-breath analysis

The delay between air flow and gas concentration signals is generally assumed to be constant within a breath as well as from breath to breath, but it was not possible to examine the constancy of the delay with the delay determination techniques so far available. Thus we developed new methods for respiratory phase detection and delay determination. The presented algorithm for the detection of the start of inspiration and expiration (phase detection) replaces the generally used valve assembly with two pneumotachographs. Now, the pneumotachograph is used in a bidirectional mode, but with a volume criterion for phase detection replacing the less reliable threshold criterion. To measure the delay between flow and gas concentration signals, a test gas is periodically injected as a marker. This test gas contains less N2 than ambient air. Therefore, the delay is determined as time between the moment of injection and the drop of N2. These two methods rendered it possible to examine delay variations and their consequences. The investigation of various breathing patterns demonstrated that the usually assumed errors caused by delay uncertainty are underestimated. We suggest reliance on a breath-by-breath delay determination to account for delay variations.     

Compatible solutes as protectants for zymogens against proteolysis

Compatible solutes are small organic osmoprotectants that have the capability to stabilize proteins. In coupled assays, the effect of the solutes ectoine, hydroxyectoine and betaine on the activation of the zymogens trypsinogen and chymotrypsinogen, catalyzed by enteropeptidase and trypsin, respectively, was studied. To different extents, all solutes protected the zymogens against activation. Ectoine (800 mM) was the most potent solute in reducing the formation of trypsin to 4% of the control value and of chymotrypsin to 23%. In separate experiments, the ability of the solutes to preserve proteolytic activity during incubation was investigated. After 4 h, trypsin and chymotrypsin completely lost their activity, but in the presence of ectoine, approximately 50% residual activity was maintained. It is proposed that a conformational shift of the protein towards folded, native-like states induced by preferential exclusion of the solute is responsible for the stabilizing and chaperone-like effects.     

Iron chelation in the biological activity of curcumin

Curcumin is among the more successful chemopreventive compounds investigated in recent years, and is currently in human trials to prevent cancer. The mechanism of action of curcumin is complex and likely multifactorial. We have made the unexpected observation that curcumin strikingly modulates proteins of iron metabolism in cells and in tissues, suggesting that curcumin has properties of an iron chelator. Curcumin increased mRNA levels of ferritin and GSTalpha in cultured liver cells. Unexpectedly, however, although levels of GSTalpha protein increased in parallel with mRNA levels in response to curcumin, levels of ferritin protein declined. Since iron chelators repress ferritin translation, we considered that curcumin may act as an iron chelator. To test this hypothesis, we measured the effect of curcumin on transferrin receptor 1, a protein stabilized under conditions of iron limitation, as well as the ability of curcumin to activate iron regulatory proteins (IRPs). Both transferrin receptor 1 and activated IRP, indicators of iron depletion, increased in response to curcumin. Consistent with the hypothesis that curcumin acts as an iron chelator, mice that were fed diets supplemented with curcumin exhibited a decline in levels of ferritin protein in the liver. These results suggest that iron chelation may be an additional mode of action of curcumin.