Density and genetic relatedness increase dispersal distance in a subsocial organism

Although dispersal distance plays a major role in determining whether organisms will reach new habitats, empirical data on the environmental factors that affect dispersal distance are lacking. Population density and kin competition are two factors theorised to increase dispersal distance. Using the two-spotted spider mite as a model species, we altered these two environmental conditions and measured the mean dispersal distance of individuals, as well as other attributes of the dispersal kernel. We find that both density and relatedness in the release patch increase dispersal distance. Relatedness, but not density, changes the shape of the dispersal kernel towards a more skewed and leptokurtic shape including a longer 'fat-tail'. This is the first experimental demonstration that kin competition can shape the whole distribution of dispersal distances in a population, and thus affect the geographical spread of dispersal phenotypes.

[Acquired von Willebrand's disease type 2A following arteriovenous fistula for haemodialysis?]

Acquired von Willebrand's disease (aVWD) is considered to be an underestimated cause of unexplained bleeding. Adsorption of von Willebrand factor (VWF) to tumour cells or hydroxyethyl starch and elimination of VWF by autoantibodies as well as shear stress-induced mechanical alteration of VWF with concomitant cleavage by enzymes may lead to an acquired deficiency of VWF and a bleeding disorder. We report a 39-year-old woman who developed spontaneous bleeding five years after surgical creation of an arteriovenous fistula (AVF) for haemodialysis treatment. AVWD type 2A was diagnosed after successful renal transplantation. One year after surgical closure of the AVF, the aVWD could not be verified again. Thus, the aVWD may have developed because of altered blood flow and shear stress inside the arteriovenous fistula.

Texture classification by statistical learning from morphological image processing: application to metallic surfaces

A classification method based on textural information for metallic surfaces displaying complex random patterns is proposed. Because these kinds of textures show fluctuations at a small scale and some uniformity at a larger scale, a probabilistic approach is followed, considering textural variations as realizations of random functions. Taking into account information of pixel neighbourhoods, the texture for each pixel is described at different scales. By means of statistical learning, the most relevant textural descriptors are selected for each application. The performance of this approach is established on a real data set of steel surfaces.

Klinische Möglichkeiten zur Steuerung der Körpertemperatur

The constancy of body temperature (CBT) is a cornerstone of homeostatic, homothermic organisms and is essential for a regulated course of biochemical and biophysical reactions. Severe deviations from normothermia (36.8+/-0.4 degrees C) are life threatening and even a moderate perioperative reduction of the CBT is coupled with an increased morbidity and mortality especially in high-risk patients. The relevant factors are coagulation disturbances, increased infection rate and increased cardiac risk. Normothermia should be achieved by the consistent use of warmth-conserving measures. On the other hand, a deliberate reduction in temperature or induced hypothermia is a neuroprotective procedure, which offers a therapeutic option to minimize neuronal secondary damage after primary hypoxic-ischemic events as well as extending the neuronal tolerance to ischemia. Management includes the practice of cooling down to a defined temperature, rewarming as well as a differentiated control of various parameters. Furthermore, side-effects which increase in severity with decreasing temperature must be taken into consideration.

Final report of a phase II trial of nimotuzumab in the treatment of refractory and relapsed high-grade gliomas in children and adolescents

2006

Background: Despite multimodal therapy most children with high grade gliomas (HGG), including glioblastoma multiforme (GM), anaplastic astrocytoma (AA) and intrinsic pontine glioma (PG) have an infaust prognosis if they relapse or are refractory to the primary treatment. Recently novel therapeutic approaches are investigated in order to improve the survival of these patients while preserving a good quality of life. This multicentre phase II trial was designed to explore the feasibility and efficacy of the h-R3 monoclonal anti-EGFR antibody (nimotuzumab) in the treatment of these patients. Patients and Methods: Pediatric patients with GM, AA or PG with radiologically proven progressive disease following primary or relapse treatment and a life expectancy of less than 4 weeks were eligible to the study. The treatment consisted of an induction therapy including a weekly short infusion of 150 mg/m2 nimotuzumab for six weeks, and in case of non-PD a consolidation therapy of 4 infusions in a 3 week interval. The response was documented by MRI in week 8 and 21 and only clinically in rapidly progresssive disease. Results: Between June 2004 and April 2006 47 patients aged 4 to 17 years (median 11 years) were enrolled in this study. 46 patients were evaluable for response. According to RECIST 14 out of 46 patients showed objective responses (PR n=4, SD n=10) in the MRI as the best response with a median change in the largest diameter of the index lesion of -11% (-50% to +16%). The PR/SD were seen in 2/13 patients with GM, 2/11 with AA and 10/22 with PG. Thirteen patients continued with the consolidation therapy and showed 4 PR, 3 SD and 6 PD in week 21. The median overall survival was 4.4 months (0.3–25.4 months) and was significantly better for repsonders (median 10 months) than for nonresponders (median 4.0 months). No severe side effects related to the study medication were observed. Conclusions: These data suggest that the repeated application of nimotuzumab is well tolerated and safe. Nimotuzumab has cytotoxic efficacy in heavily pre- treated relapsed HGG. Based on this data a phase III trial with nimotuzumab in newly diagnosed diffuse intrinsic pontine gliomas concomittent with radiotherapy was introduced in first quarter 2006.

No significant financial relationships to disclose.