Modeling Calcium Concentration and Biochemical Reactions

Almost all regions of the brain receive one or more neuromodulatory inputs, and disrupting these inputs produces deficits in neuronal function. Neuromodulators act through intracellular second messenger pathways to influence the electrical properties of neurons, integration of synaptic inputs, spatio-temporal firing dynamics of neuronal networks, and, ultimately, systems behavior. Second messengers pathways consist of series of bimolecular reactions, enzymatic reactions, and diffusion. Calcium is the second messenger molecule with the most effectors, and thus is highly regulated by buffers, pumps and intracellular stores. Computational modeling provides an innovative, yet practical method to evaluate the spatial extent, time course and interaction among second messenger pathways, and the interaction of second messengers with neuron electrical properties. These processes occur both in compartments where the number of molecules are large enough to describe reactions deterministically (e.g. cell body), and in compartments where the number of molecules is small enough that reactions occur stochastically (e.g. spines). – In this tutorial, I explain how to develop models of second messenger pathways and calcium dynamics. The first part of the tutorial explains the equations used to model bimolecular reactions, enzyme reactions, calcium release channels, calcium pumps and diffusion. The second part explains some of the GENESIS, Kinetikit and Chemesis objects that implement the appropriate equations. In depth explanation of calcium and second messenger models is provided by reviewing code, both in XPP, Chemesis and Kinetikit, that implements simple models of calcium dynamics and second messenger cascades.

Marked Silence, Neo-Feudalistic Reactions and the Stabilized Moral Regime – The Current De- and Reformation of „the Social“

The German chancellor and leader of the German conservative party, Angela Merkel, said in an interview a few weeks ago: “Nobody could have imagined a few months ago to what extent we would be pushed into state intervention programs. Of course, Merkel spoke on, this intervention is not easy for anybody. Therefore, she recommended turning back to the former course as soon as possible” (tagesschau.de, 11. März 2008, zit. nach Bildzeitungsinterview mit Angela Merkel, own translation). The worldwide celebrated new president of the United States, Barack Obama, said in an interview on CBS-News a few weeks before Merkel: “(...) there's no doubt that we have not been able yet to reset the confidence in the financial markets and in the consumer markets and among businesses that allow the economy to move forward in a strong way. And my job as president is gonna be to make sure that we restore that confidence“ (CBS News, 16. November 2008, Obama On Economic Crisis, Transition; http://www.cbsnews.com/stories/2008/11/16/60minutes/main4607893.shtml; Stand: 16. April 2009).

Do victimization experiences accentuate reactions to ostracism? An experiment using cyberball

Based on the notion that the history of victimization has an impact on the sensitivity to current victimization situations this study investigated whether victims of bullying show more pronounced responses to single episodes of social exclusion. We examined whether victimization experiences in school are associated with responses to ostracism in a virtual ball tossing game (Cyberball). We compared two groups of students: 26 victims of bullying and 32 students not involved in bully/victim problems (mean age = 12.12). After playing Cyberball, the victimized students in the ostracism condition scored significantly lower on feelings of meaningful existence compared to the ostracized students not involved in bully/victim problems. These results strongly support the idea that previously victimized students are more affected by experiences of social exclusion than students who are not involved in bully/victim problems.

Agrobacterium ParA/MinD-like VirC1 spatially coordinates early conjugative DNA transfer reactions.

Agrobacterium tumefaciens translocates T-DNA through a polar VirB/D4 type IV secretion (T4S) system. VirC1, a factor required for efficient T-DNA transfer, bears a deviant Walker A and other sequence motifs characteristic of ParA and MinD ATPases. Here, we show that VirC1 promotes conjugative T-DNA transfer by stimulating generation of multiple copies per cell of the T-DNA substrate (T-complex) through pairwise interactions with the processing factors VirD2 relaxase, VirC2, and VirD1. VirC1 also associates with the polar membrane and recruits T-complexes to cell poles, the site of VirB/D4 T4S machine assembly. VirC1 Walker A mutations abrogate T-complex generation and polar recruitment, whereas the native protein recruits T-complexes to cell poles independently of other polar processing factors (VirC2, VirD1) or T4S components (VirD4 substrate receptor, VirB channel subunits). We propose that A. tumefaciens has appropriated a progenitor ParA/MinD-like ATPase to promote conjugative DNA transfer by: (i) nucleating relaxosome assembly at oriT-like T-DNA border sequences and (ii) spatially positioning the transfer intermediate at the cell pole to coordinate substrate-T4S channel docking.

Intensive In-Home Family-Based Services: Reactions from Consumers and Providers

An intensive family preservation program was examined through interviews with 31 families who received the services and four caseworkers who provided the services. The primary finding from interviews with both care givers and caseworkers was that a positive therapeutic relationship between the worker and the client family contributes most to the success of the program. Workers who provided the services stressed the need for making concrete services available as well as clinical intervention and skills training, and they were adamant about screening families for appropriateness before including them in an intensive, inhome program.