A high-throughput microfluidic assay to study neurite response to growth factor gradients

Studying neurite guidance by diffusible or substrate bound gradients is challenging with current techniques. In this study, we present the design, fabrication and utility of a microfluidic device to study neurite guidance under chemogradients. Experimental and computational studies demonstrated the establishment of a steep gradient of guidance cue within 30 min and stable for up to 48 h. The gradient was found to be insensitive to external perturbations such as media change and movement of device. The effects of netrin-1 (0.1-10 μg mL(-1)) and brain pulp (0.1 μL mL(-1)) were evaluated for their chemoattractive potential on neurite turning, while slit-2 (62.5 or 250 ng mL(-1)) was studied for its chemorepellant properties. Hippocampal or dorsal root ganglion (DRG) neurons were seeded into a micro-channel and packed onto the surface of a 3D collagen gel. Neurites grew into the matrix in three dimensions, and a gradient of guidance cue was created orthogonal to the direction of neurite growth to impact guidance. The average turning angle of each neurite was measured and averaged across multiple devices cultured under similar conditions to quantify the effect of guidance cue gradient. Significant positive turning towards gradient was measured in the presence of brain pulp and netrin-1 (1 μg mL(-1)), relative to control cultures which received no external guidance cue (p < 0.001). Netrin-1 released from transfected fibroblasts had the most positive turning effect of all the chemoattractive cues tested (p < 0.001). Slit-2 exhibited strong chemorepellant characteristics on both hippocampal and DRG neurite guidance at 250 ng mL(-1) concentration. Slit-2 also showed similar behavior on DRG neuron invasion into 3D collagen gel (p < 0.01 relative to control cultures). Taken together, the results suggest the utility of this microfluidic device to generate stable chemogradients for studying neurobiology, cell migration and proliferation, matrix remodeling and co-cultures with other cell lines, with potential applications in cancer biology, tissue engineering and regenerative medicine.     

Nachweis der salpetrigen S?ure im Trinkwasser

Ohne Zusammenfassung     

Organische Reagenzien in der qualitativen Analyse anorganischer Stoffe

Ohne Zusammenfassung     

Fixed point theorems in generalized Hilbert spaces

Some fundamental fixed point theorems are proved for locally convex spaces whose generating family of seminorms satisfies the parallelogram law.     

Regular bases in products of power series spaces

We prove that Λ_∞(α) × Λ₁(β) has a regular basis iff Λ_∞(α) ? Λ₁(β) has a regular basis iff Λ_∞(α) ? Λ₁(β) is isomorphic to a Cartesian product of two power series spaces. We give a simple condition on α, β which determines when these equivalent statements hold.     

Ein kolloider Wärmeindikator. II

Zusammenfassung Erh?hung der W?rmeempfindlichkeit der Sulfit-Novokain-L?sungen. PhotographischeWiedergabe der Lloyd-Schichtungen, welche darin auftreten, wenn sie bei Vorhandensein eines Konzentrationsgef?lles erw?rmt werden. Deren Bildung wird eingeleitet durch eine stufenweise Aufw?rtsbewegung von L?sung, die durch die randliche Erw?rmung ein etwas geringeres spezifisches Gewicht erlangt hat. Dafür senkt sich die entsprechende Menge von kühlerer L?sung in der Mitte des Rohrs nach unten und schiebt sich als klare Schicht unter die trübe. Es mu? jedoch zugegeben werden, da? damit der Mechanismus der Schichtenbildung noch nicht in allen Einzelheiten gekl?rt ist. Die notwendige Annahme der Konvektionen beim Zustandekommen der Lloyd-B?nderung schlie?t nicht aus, da? ihre Bedeutung nach der Ausbildung stark zurücktritt. Verfestigung der Flüssigkeit durch Gelbildung kann gewisse Lloyd-B?nderungen dauernd erhalten.     

ASICA Association Internationale pour le Calcul Analogique

Ohne Zusammenfassung

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International Association for Analog Computation

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ASICA Association Internationale pour le Calcul Analogique