Milieu-adopted in vitro and in vivo differentiation of mesenchymal tissues derived from different adult human CD34-negative progenitor cell clones

Adult mesenchymal stem cells with multilineage differentiation potentially exist in the bone marrow, but have also been isolated from the peripheral blood. The differentiation of stem cells after leaving their niches depends predominately on the local milieu and its new microenvironment, and is facilitated by soluble factors but also by the close cell-cell interaction in a three-dimensional tissue or organ system. We have isolated CD34-negative, mesenchymal stem cell lines from human bone marrow and peripheral blood and generated monoclonal cell populations after immortalization with the SV40 large T-antigen. The cultivation of those adult stem cell clones in an especially designed in vitro environment, including self-constructed glass capillaries with defined growth conditions, leads to the spontaneous establishment of pleomorphic three-dimensional cell aggregates ( spheroids) from the monoclonal cell population, which consist of cells with an osteoblast phenotype and areas of mineralization along with well-vascularized tissue areas. Modifications of the culture conditions favored areas of bone-like calcifications. After the transplantation of the at least partly mineralized human spheroids into different murine soft tissue sites but also a dorsal skinfold chamber, no further bone formation could be observed, but angiogenesis and neovessel formation prevailed instead, enabling the transplanted cells and cell aggregates to survive. This study provides evidence that even monoclonal adult human CD34-negative stem cells from the bone marrow as well as peripheral blood can potentially differentiate into different mesenchymal tissues depending on the local milieu and responding to the needs within the microenvironment. Copyright (C) 2005 S. Karger AG, Basel

Nucleate pool boiling investigation on a silicon test section with micro-fabricated cavities

The basic mechanisms of nucleate boiling are still not completely understood, in spite of the many numerical and experimental studies dedicated to the topic. The use of a hybrid code allows reasonable computational times for simulations of a solid plate with a large population of artificial micro-cavities with fixed distribution. This paper analyses the guidelines for the design, through numerical simulations, of the location and sizes of micro-fabricated cavities on a new silicon test section immersed in FC-72 at the saturation temperature for different pressures with an imposed heat flux applied at the back of the plate. Particular focus is on variations of wall temperature around nucleation sites

Applying individuation to conflicting social categories

The ability to differentiate individuals from their group memberships (individuation) is useful in forming impressions when social categorization fails to do so. This method is particularly valuable when encountering incongruent social category conjunctions (e.g., female bricklayer). We tested the notion that individuation is initiated when applying cognitively effortful explanatory, emergent attributes to incongruent conjunctions. Incongruent category conjunctions were more likely to be comprised of emergent attributes and individuation moderated the application of these attributes in Experiment 1. In Experiment 2, individuation again moderated emergent attribute application for incongruent conjunctions, but cognitive load attenuated the relationship. Allowing or preventing the generation of attributes did not affect individuation for incongruent conjunctions in Experiment 3. This ruled out the possibility that emergent attributes cause increased individuation, but does not rule out the notion that individuation precedes such explanatory attributes. Together these findings suggest that individuating those whose category memberships clash may be applied in the effortful application of explanatory emergent attributes

Visualization of leukocyte transendothelial and interstitial migration using reflected light oblique transillumination in intravital video microscopy

Dynamic visualization of the intravascular events leading to the extravasation of leukocytes into tissues by intravital microscopy has significantly expanded our understanding of the underlying molecular processes. In contrast, the detailed observation of leukocyte transendothelial and interstitial migration in vivo has been hampered by the poor image contrast of cells within turbid media that is obtainable by conventional brightfield microscopy. Here we present a microscopic method, termed reflected light oblique transillumination microscopy, that makes use of the optical interference phenomena generated by oblique transillumination to visualize subtle gradients of refractive indices within tissues for enhanced image contrast. Using the mouse cremaster muscle, we demonstrate that this technique makes possible the reliable quantification of extravasated leukocytes as well as the characterization of morphological phenomena of leukocyte transendothelial and interstitial migration

Single-qubit lasing and cooling at the Rabi frequency

For a superconducting qubit driven to perform Rabi oscillations and coupled to a slow electromagnetic or nano-mechanical oscillator we describe previously unexplored quantum optics effects. When the Rabi frequency is tuned to resonance with the oscillator the latter can be driven far from equilibrium. Blue detuned driving leads to a population inversion in the qubit and a bi-stability with lasing behavior of the oscillator; for red detuning the qubit cools the oscillator. This behavior persists at the symmetry point where the qubit-oscillator coupling is quadratic and decoherence effects are minimized. There the system realizes a "single-atom-two-photon laser".Comment: Replaced with final published version, fig. 2 compresse

Role of protein kinase C in inhibition of renin release caused by vasoconstrictors

It was the aim of the present study to get insight into some of the intracellular mechanisms by which the vasoconstrictor hormones angiotensin II (ANG II), arginine vasopressin (AVP), and norepinephrine (NE) inhibit renin release from renal juxtaglomerular cells. To this end a primary cell culture from rat renal cortex was established that consisted of 50% juxtaglomerular cells. The cultured juxtaglomerular cells contained prominent renin granules closely resembling those in the intact kidney and responded to a number of stimuli of renin release. By using these cultures, we found that ANG II (10(-7) M), AVP (10(-6) M), and NE (10(-5) M) inhibited renin release and increased the calcium permeability of the plasma membrane of the cultured cells. Both the effects on renin release and on calcium permeability could be diminished or even be abolished by the calcium channel blocker verapamil (Vp) (10(-5) M). ANG II, AVP, and NE led to an increased formation of diacylglycerol (DAG), a well-known stimulator of protein kinase C (PKC). Moreover, a direct stimulation of PKC by 12-O-tetradecanoylphorbol-13-acetate (TPA) (10(-8)-10(-6) M) also inhibited renin release and increased the calcium permeability of the cell membrane. Similar to ANG II, AVP, and NE, the effects of TPA on calcium permeability and renin release could be diminished by Vp. In conclusion, these results point toward a common mechanism by which vasoconstrictors inhibit renin release from renal juxtaglomerular cells: ANG II, AVP, and NE activate a phospholipase C, which generates DAG.(ABSTRACT TRUNCATED AT 250 WORDS

Keep Rollin' - Whole-Body Motion Control and Planning for Wheeled Quadrupedal Robots

We show dynamic locomotion strategies for wheeled quadrupedal robots, which combine the advantages of both walking and driving. The developed optimization framework tightly integrates the additional degrees of freedom introduced by the wheels. Our approach relies on a zero-moment point based motion optimization which continuously updates reference trajectories. The reference motions are tracked by a hierarchical whole-body controller which computes optimal generalized accelerations and contact forces by solving a sequence of prioritized tasks including the nonholonomic rolling constraints. Our approach has been tested on ANYmal, a quadrupedal robot that is fully torque-controlled including the non-steerable wheels attached to its legs. We conducted experiments on flat and inclined terrains as well as over steps, whereby we show that integrating the wheels into the motion control and planning framework results in intuitive motion trajectories, which enable more robust and dynamic locomotion compared to other wheeled-legged robots. Moreover, with a speed of 4 m/s and a reduction of the cost of transport by 83 % we prove the superiority of wheeled-legged robots compared to their legged counterparts.Comment: IEEE Robotics and Automation Letter