Biological scanning electrochemical microscopy and its application to live cell studies

Progress in instrumental design continues to pave the way for high-resolution, real-time electrochemical measurements with living cells.     

Enhancing Cell therapies from the Outside In: Cell Surface Engineering Using Synthetic Nanomaterials

Therapeutic treatments based on the injection of living cells are in clinical use and preclinical development for diseases ranging from cancer to cardiovascular disease to diabetes. To enhance the function of therapeutic cells, a variety of chemical and materials science strategies are being developed that engineer the surface of therapeutic cells with new molecules, artificial receptors, and multifunctional nanomaterials, synthetically endowing donor cells with new properties and functions. These approaches offer a powerful complement to traditional genetic engineering strategies for enhancing the function of living cells.     

On auto- and cross-interdependence in interval field finite element analysis

This paper discusses the concepts of auto- and cross-interdependence in interval field finite element analysis. In classic interval analysis, independent intervals are used to construct hyper-rectangular input spaces that correspond to the bounded uncertainty that is present on some model parameters. This is a direct result from the inability of modeling interdependence. Such assumption of complete independence might prove in some cases to be highly over-conservative. A first example is the modeling of spatial uncertainty, where the interdependence is governed by allowable spatial gradients of field realizations. Secondly, interdependence can also occur in case uncertainty in several structural quantities has the same root cause (eg, the manufacturing process). Recent work by the authors introduced concepts for modeling dependence between intervals in a spatial and multivariate context. However, it is unclear how an analyst has to deal with multiple quantities that have a spatial uncertainty component and are furthermore interdependent. This paper presents an approach to link multiple interval fields using recently introduced convex hull pair constructions and inverse distance weighting interpolation. Two case studies to illustrate the new methodology are included, proving the flexibility of the methodology in the modeling of auto- and cross-interdependence between multiple interval scalars and/or interval fields.     

Tailoring of free standing microchannels structures via microtemplating

The preparation of ceramic microchannel structures from powder based material is a time consuming, expensive or inflexible process. This work demonstrates microtemplating - a new reliable and economical fabrication method for preparing ceramic alumina self-supporting microchannels with diameters from 10 to 1000 μm. The basis for this method is the controlled dip-coating of a sacrificial polymeric fiber template with suspensions containing sinterable particles. Subsequent sintering results in self-supporting ceramic microchannels. Thermal behavior of a microtemplate is critical for achieving self-supporting microchannels. We used polyamide, keratin, para-aramide, polypropylene, and polyimide fibers to set models of microtemplate thermal behavior. We found that the negative influence of thermal expansion and gas production could be eliminated by microtemplates with hollow and porous internal structure. Furthermore we show flexibility of the green stage procedure on an alumina microfluidic loop and a multichannel system with gradient porosity. The microtemplating is demonstrated to be an inexpensive and flexible process.     

Constant-distance mode scanning potentiometry. 1. Visualization of calcium carbonate dissolution in aqueous solution

Constant-distance mode scanning potentiometry was established by integrating potentiometric microsensors as ion-selective scanning probes into a SECM setup that was equipped with a piezoelectric shear force-based tip-to-sample distance control. The combination of specially designed micrometer-sized potentiometric tips with an advanced system for tip positioning allowed simultaneous acquisition of both topographic and potentiometric information at solid/liquid interfaces with high spatial resolution. The performance of the approach was evaluated by applying Ca(2+)-selective constant-distance mode potentiometry to monitor the dissolution of calcium carbonate occurring either at the (104) surface of calcite crystals or in proximity to the more complex surface of cross sections of a calcium carbonate shell of Mya arenaria exposed to slightly acidic aqueous solutions. Micrometer-scale heterogeneities in the apparent calcium activity profiles have successfully been resolved for both samples.     

Coherent lower previsions in systems modelling: products and aggregation rules

We discuss why coherent lower previsions provide a good uncertainty model for solving generic uncertainty problems involving possibly conflicting expert information. We study various ways of combining expert assessments on different domains, such as natural extension, independent natural extension and the type-I product, as well as on common domains, such as conjunction and disjunction. We provide each of these with a clear interpretation, and we study how they are related. Observing that in combining expert assessments no information is available about the order in which they should be combined, we suggest that the final result should be independent of the order of combination. The rules of combination we study here satisfy this requirement.     

Anticipatory stress influences decision making under explicit risk conditions.

Recent research has suggested that stress may affect memory, executive functioning, and decision making on the basis of emotional feedback processing. The current study examined whether anticipatory stress affects decision making measured with the Game of Dice Task (GDT), a decision-making task with explicit and stable rules that taps both executive functioning and feedback learning. The authors induced stress in 20 participants by having them anticipate giving a public speech and also examined 20 comparison subjects. The authors assessed the level of stress with questionnaires and endocrine markers (salivary cortisol and alpha-amylase), both revealing that speech anticipation led to increased stress. Results of the GDT showed that participants under stress scored significantly lower than the comparison group and that GDT performance was negatively correlated with the increase of cortisol. Our results indicate that stress can lead to disadvantageous decision making even when explicit and stable information about outcome contingencies is provided. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Knowing me, knowing you: The accuracy and unique predictive validity of self-ratings and other-ratings of daily behavior.

Many people assume that they know themselves better than anyone else knows them. Recent research on inaccuracies in self-perception, however, suggests that self-knowledge may be more limited than people typically assume. In this article, the authors examine the possibility that people may know a person as well as (or better than) that person knows himself or herself. In Study 1, the authors document the strength of laypeople's beliefs that the self is the best expert. In Study 2, the authors provide a direct test of self- and other-accuracy using an objective and representative behavioral criterion. To do this, the authors compared self- and other-ratings of daily behavior to real-life measures of act frequencies assessed unobtrusively over 4 days. Our results show that close others are as accurate as the self in predicting daily behavior. Furthermore, accuracy varies across behaviors for both the self and for others, and the two perspectives often independently predict behavior. These findings suggest that there is no single perspective from which a person is known best and that both the self and others possess unique insight into how a person typically behaves. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Neurobiological correlates of the antidepressant action of electroconvulsive therapy

The activation of adenosine receptors has recently been demonstrated to stimulate haematopoiesis. In the present study, we investigated the ability of drugs elevating extracellular adenosine to influence curative effects of granulocyte colony-stimulating factor (G-CSF) in mice exposed to a sublethal dose of 4 Gy of 60Co radiation. Elevation of extracellular adenosine in mice was induced by the combined administration of dipyridamole, a drug inhibiting the cellular uptake of adenosine, and adenosine monophosphate (AMP), an adenosine prodrug. The effects of dipyridamole plus AMP, and G-CSF, administered either alone or in combination, were evaluated. The drugs were injected to mice in a 4-d treatment regimen starting on d 3 after irradiation and the haematopoietic response was evaluated on d 7, 10, 14, 18 and 24 after irradiation. While the effects of G-CSF on the late maturation stages of blood cells, appearing shortly after the completion of the treatment, were not influenced by dipyridamole plus AMP, positive effects of the combination therapy occurred in the post-irradiation recovery phase which is dependent on the repopulation of haematopoietic stem cells. This was indicated by the significant elevation of counts of granulocyte-macrophage progenitor cells (GM-CFC) and granulocytic cells in the bone marrow (d 14), of GM-CFC (d 14), granulocytic and erythroid cells (d 14 and 18) in the spleen, and of neutrophils (d 18), monocytes (d 14 and 18) and platelets (d 18) in the peripheral blood. These effects suggest that the repopulation potential of the combination therapy lies in a common multilineage cell population. The results of this study implicate the promising possibility to enhance the curative effects of G-CSF under conditions of myelosuppressive states induced by radiation exposure.     

Prefrontal and cerebellar abnormalities in major depression: evidence from oculomotor studies

BACKGROUND: Neurobehavioral studies have identified multiple cognitive and motor system disturbances in depressed patients. Neuroimaging studies have identified abnormalities in neocortex, striatum, and cerebellar vermis that are probable causes of these impairments. METHODS: To further clarify the origins of motor and cognitive disturbances in major depression, unmedicated depressed inpatients (n = 29) and an age- and gendermatched healthy comparison group (n = 19) were tested with a battery of oculomotor tasks selected to assess the functional integrity of frontostriatal circuitry and the cerebellar vermis. RESULTS: Depressed patients demonstrated increased rates of response suppression errors on an antisaccade task, less accurate memory for spatial location information in a spatial delayed response task, dysmetric visually guided saccades, and increased rates of saccadic intrusions during visual fixation. CONCLUSIONS: These results provide quantitative documentation of significant disturbances in neurophysiological processes subserved by prefrontal cortex and the cerebellar vermis during episodes of major depression.