Response of maize biomass and soil water fluxes on elevated CO2 and drought-From field experiments to process-based simulations.

The rising concentration of atmospheric carbon dioxide (CO2 ) is known to increase the total aboveground biomass of several C3 crops, whereas C4 crops are reported to be hardly affected when water supply is sufficient. However, a free-air carbon enrichment (FACE) experiment in Braunschweig, Germany, in 2007 and 2008 resulted in a 25% increased biomass of the C4 crop maize under restricted water conditions and elevated CO2 (550 ppm). To project future yields of maize under climate change, an accurate representation of the effects of eCO2 and drought on biomass and soil water conditions is essential. Current crop growth models reveal limitations in simulations of maize biomass under eCO2 and limited water supply. We use the coupled process-based hydrological-plant growth model Catchment Modeling Framework-Plant growth Modeling Framework to overcome this limitation. We apply the coupled model to the maize-based FACE experiment in Braunschweig that provides robust data for the investigation of combined CO2 and drought effects. We approve hypothesis I that CO2 enrichment has a small direct-fertilizing effect with regard to the total aboveground biomass of maize and hypothesis II that CO2 enrichment decreases water stress and leads to higher yields of maize under restricted water conditions. Hypothesis III could partly be approved showing that CO2 enrichment decreases the transpiration of maize, but does not raise soil moisture, while increasing evaporation. We emphasize the importance of plant-specific CO2 response factors derived by use of comprehensive FACE data. By now, only one FACE experiment on maize is accomplished applying different water levels. For the rigorous testing of plant growth models and their applicability in climate change studies, we call for datasets that go beyond single criteria (only yield response) and single effects (only elevated CO2 ).

Development and evaluation of a software system for medical students to teach and practice anamnestic interviews with virtual patient avatars.

BACKGROUND AND OBJECTIVES: Taking a medical history is a core competence of the diagnostic process. At the beginning of their study medical students need to learn and practice the necessary techniques, initially focusing on good structuring and completeness. For this purpose, an interactive software system (ViPATalk) was developed in which the student can train to pose questions to virtual patient avatars in free conversation. At the end, the student receives feedback on the completeness of the questioning and an explanation of the essential items. The use of this software was compared to the traditional format of student role play in a randomized trial. METHODS: The central component of ViPATalk is a chatbot based on the AI language AIML, which generates an appropriate answer based on keywords in the student's question. To enable a realistic use, the student can enter the question via microphone (speech-to-text) and the answer generated by the chatbot is presented as a short video sequence, where the avatar is generated from a real image. Here, the transition between the sequences is seamless, resulting in a continuous movement of the avatar during the conversation. RESULTS: The learning success by practicing with ViPATalk was tested in an anamnestic interview with actors as simulated patients. The completeness of the conversation was evaluated with regard to numerous aspects and also certain behaviors during the conversation. These results were compared with those after practicing using peer role play. CONCLUSIONS: It was found that practicing with ViPATalk was mostly equivalent to the students' role play. In the subsequent survey of the students, the wish was expressed that the ViPATalk software should also be used as an online tool for self-study and that there should be more cases for practicing.

Interaction between the keratin cytoskeleton and eEF1Bgamma affects protein synthesis in epithelial cells.

Eukaryotic elongation factor-1 (eEF1) is essential for peptide-chain elongation during translation. We report that its gamma subunit (eEF1Bgamma) specifically binds, and bundles, keratin intermediate filaments. Disrupting this interaction depresses translation by approximately 20% and selectively increases 80S ribosomes in epithelial cells, an outcome recapitulated by RNA interference-mediated silencing of eEF1Bgamma. These findings extend the emerging relationship between keratin proteins and the translational machinery.

Globally consistent influences of seasonal precipitation limit grassland biomass response to elevated CO2.

Rising atmospheric carbon dioxide concentration should stimulate biomass production directly via biochemical stimulation of carbon assimilation, and indirectly via water savings caused by increased plant water-use efficiency. Because of these water savings, the CO2 fertilization effect (CFE) should be stronger at drier sites, yet large differences among experiments in grassland biomass response to elevated CO2 appear to be unrelated to annual precipitation, preventing useful generalizations. Here, we show that, as predicted, the impact of elevated CO2 on biomass production in 19 globally distributed temperate grassland experiments reduces as mean precipitation in seasons other than spring increases, but that it rises unexpectedly as mean spring precipitation increases. Moreover, because sites with high spring precipitation also tend to have high precipitation at other times, these effects of spring and non-spring precipitation on the CO2 response offset each other, constraining the response of ecosystem productivity to rising CO2. This explains why previous analyses were unable to discern a reliable trend between site dryness and the CFE. Thus, the CFE in temperate grasslands worldwide will be constrained by their natural rainfall seasonality such that the stimulation of biomass by rising CO2 could be substantially less than anticipated.

Thymic pathologies in myasthenia gravis: a preoperative assessment of CAT scan and nuclear based imaging.

Precise diagnostic work up of a suspected thymic pathology in patients with myasthenia gravis (MG) is very important for potential surgical implications and further disease course. In this study the diagnostic value of combined preoperative radiological (CAT scan) and nuclear based imaging (octreotide and thallium scintigraphy) in patients with MG was evaluated. Twenty four patients were included. Histopathology revealed thymoma in nine patients, thymic carcinoma (TC) in one patient, lymphofollicular hyperplasia in seven patients, and involuted thymus in another seven patients. Diagnostic sensitivity for detecting thymoma/TC was 80 % in CAT scan as well as in somatostatin scintigraphy; the combination of both procedures reached 90 %. However, the diagnostic specifity to exclude thymoma in CAT scan was 100 % and in octreotide scintigraphy 85.7 %. Semiquantitative octreotide uptake significantly correlated with histological grading of thymoma/TC (r = 0.764) and histological proliferation rate Ki67 (r = 0.894). Thallium scintigraphy was positive only in one out of four thymoma cases. In this study, somatostatin scintigraphy has been shown to be a useful additional diagnostic technique in detecting thymic malignancies in patients with MG. These results might be especially helpful in patients with late onset MG as these patients are in general no candidates for thymectomy.

Actions of two naturally occurring saturated N-acyldopamines on transient receptor potential vanilloid 1 (TRPV1) channels.

Four long-chain, linear fatty acid dopamides (N-acyldopamines) have been identified in nervous bovine and rat tissues. Two unsaturated members of this family of lipids, N-arachidonoyl-dopamine (NADA) and N-oleoyl-dopamine, were shown to potently activate the transient receptor potential channel type V1 (TRPV1), also known as the vanilloid receptor type 1 for capsaicin. However, the other two congeners, N-palmitoyl- and N-stearoyl-dopamine (PALDA and STEARDA), are inactive on TRPV1. We have investigated here the possibility that the two compounds act by enhancing the effect of NADA on TRPV1 ('entourage' effect). When pre-incubated for 5 min with cells, both compounds dose-dependently enhanced NADA's TRPV1-mediated effect on intracellular Ca(2+) in human embryonic kidney cells overexpressing the human TRPV1. In the presence of either PALDA or STEARDA (0.1-10 microm), the EC(50) of NADA was lowered from approximately 90 to approximately 30 nm. The effect on intracellular Ca(2+) by another endovanilloid, N-arachidonoyl-ethanolamine (anandamide, 50 nm), was also enhanced dose-dependently by both PALDA and STEARDA. PALDA and STEARDA also acted in synergy with low pH (6.0-6.7) to enhance intracellular Ca(2+) via TRPV1. When co-injected with NADA (0.5 micrograms) in rat hind paws, STEARDA (5 micrograms) potentiated NADA's TRPV1-mediated nociceptive effect by significantly shortening the withdrawal latencies from a radiant heat source. STEARDA (1 and 10 micrograms) also enhanced the nocifensive behavior induced by carrageenan in a typical test of inflammatory pain. These data indicate that, despite their inactivity per se on TRPV1, PALDA and STEARDA may play a role as 'entourage' compounds on chemicophysical agents that interact with these receptors, with possible implications in inflammatory and neuropathic pain.

Preview. SKPing a hurdle: Sox2 and adult dermal stem cells.

In this issue of Cell Stem Cell, Biernaskie et al. (2009) demonstrate that a specific subpopulation of dermal papilla fibroblasts, marked by Sox2 expression, displays properties of adult stem cells, including serial hair follicle initiation, dermal cell differentiation, and skin-derived precursor production.

Keratins and protein synthesis: the plot thickens.

In addition to protecting epithelial cells from mechanical stress, keratins regulate cytoarchitecture, cell growth, proliferation, apoptosis, and organelle transport. In this issue, Vijayaraj et al. (2009. J. Cell Biol. doi:10.1083/jcb.200906094) expand our understanding of how keratin proteins participate in the regulation of protein synthesis through their analysis of mice lacking the entire type II keratin gene cluster.