An IFN-γ and TNF-α dual release fluorospot assay for diagnosing active tuberculosis.

OBJECTIVES: Currently available interferon (IFN)-γ-release assays (IGRA) cannot discriminate active tuberculosis (TB) from latent TB infection (LTBI), and so have limited clinical utility for diagnosing active TB. Since numbers of tumour necrosis factor (TNF)-α-producing T cells are highly correlated with active TB, we hypothesized that detecting IFN-γ- and/or TNF-α-producing T cells would overcome this limitation of IGRA. This study evaluated the diagnostic performances of the IFN-γ and TNF-α dual release fluorospot assay for active TB. METHODS: Adult patients with suspected TB including recent TB exposers were prospectively enrolled over a 28-month period. In addition to the conventional IGRA test (i.e. QuantiFERON-In-Tube), a fluorospot assay for detecting IFN-γ- and TNF-α-producing T cells was performed. The final diagnoses were classified by clinical category. Patients with confirmed or probable TB were regarded as active TB, and patients with not active TB were further classified as having not active TB with and without LTBI, based on the QuantiFERON-In-Tube results. RESULTS: A total of 153 patients including 45 with active TB and 108 with not active TB (38 LTBI vs. 70 not LTBI) were finally analysed. The sensitivity and specificity of the QuantiFERON-In-Tube assay for active TB were 84% (95% confidence interval (CI), 70-93) and 70% (95% CI 61-79), respectively. The IFN-γ/TNF-α dual release assay by fluorospot had substantially higher diagnostic specificity (94%) for diagnosing active TB than the IFN-γ single release assay (72%, p < 0.001), without compromising sensitivity (84% vs. 89%, p 0.79). CONCLUSIONS: The fluorospot-based IFN-γ/TNF-α dual release assay appears to be a simple and useful test for diagnosing active TB.

Hybrid polymer microfluidic platform to mimic varying vascular compliance and topology.

Several cardiovascular pathologies and aging have been associated with alterations in the mechanical and structural properties of the vascular wall, leading to a reduction in arterial compliance and the development of constriction. In the past, rare efforts have been directed to understand the endothelial cell response to combined mechanical stimuli from fluid flow and substrate rigidity. Recent approaches using microfluidic platforms have limitations in precisely mimicking healthy and diseased vasculature conditions from altered topological and substrate compliance perspectives. To address this, we demonstrated an effective fabrication process to realize a hybrid polymer platform to test these mechanistic features of blood vessels. The salient features of the platform include circular microchannels of varying diameters, variation in substrate rigidity along the channel length, and the coexistence of microchannels with different cross sections on a single platform. The platform demonstrates the combined effects of flow-induced shear forces and substrate rigidity on the endothelial cell layer inside the circular microchannels. The experimental results indicate a pronounced cell response to flow induced shear stress via its interplay with the underlying substrate mechanics.

Demonstration of Confined Electron Gas and Steep-Slope Behavior in Delta-Doped GaAs-AlGaAs Core-Shell Nanowire Transistors.

Strong surface and impurity scattering in III-V semiconductor-based nanowires (NW) degrade the performance of electronic devices, requiring refined concepts for controlling charge carrier conductivity. Here, we demonstrate remote Si delta (δ)-doping of radial GaAs-AlGaAs core-shell NWs that unambiguously exhibit a strongly confined electron gas with enhanced low-temperature field-effect mobilities up to 5 × 10(3) cm(2) V(-1) s(-1). The spatial separation between the high-mobility free electron gas at the NW core-shell interface and the Si dopants in the shell is directly verified by atom probe tomographic (APT) analysis, band-profile calculations, and transport characterization in advanced field-effect transistor (FET) geometries, demonstrating powerful control over the free electron gas density and conductivity. Multigated NW-FETs allow us to spatially resolve channel width- and crystal phase-dependent variations in electron gas density and mobility along single NW-FETs. Notably, dc output and transfer characteristics of these n-type depletion mode NW-FETs reveal excellent drain current saturation and record low subthreshold slopes of 70 mV/dec at on/off ratios >10(4)-10(5) at room temperature.

Reprogramming axonal behavior by axon-specific viral transduction.

The treatment of axonal disorders, such as diseases associated with axonal injury and degeneration, is limited by the inability to directly target therapeutic protein expression to injured axons. Current gene therapy approaches rely on infection and transcription of viral genes in the cell body. Here, we describe an approach to target gene expression selectively to axons. Using a genetically engineered mouse containing epitope-labeled ribosomes, we find that neurons in adult animals contain ribosomes in distal axons. To use axonal ribosomes to alter local protein expression, we utilized a Sindbis virus containing an RNA genome that has been modified so that it can be directly used as a template for translation. Selective application of this virus to axons leads to local translation of heterologous proteins. Furthermore, we demonstrate that selective axonal protein expression can be used to modify axonal signaling in cultured neurons, enabling axons to grow over inhibitory substrates typically encountered following axonal injury. We also show that this viral approach also can be used to achieve heterologous expression in axons of living animals, indicating that this approach can be used to alter the axonal proteome in vivo. Together, these data identify a novel strategy to manipulate protein expression in axons, and provides a novel approach for using gene therapies for disorders of axonal function.

Biochemical, biomolecular and cellular sensing in microfluidics using flow induced admittance spectra.

We present flow induced admittance spectra for electrolytes, cell culture media, different sizes of DNA solutions and neural cells using flow induced admittance spectra in a microfluidics device. The device comprises of a PDMS channel aligned with a pair of channel electrodes fabricated on glass. The peak of the flow induced admittance spectra and frequency at which the peak occurs are the key parameters used for the characterization of sensing. The response of this sensor is a function of the conductivity and dielectrivity of the effective solution. The flow induced admittances of the particles studied are corrected with their media. This sensing will be a primary component of an electrical based cytometer.

Patterned deposition of cells and proteins onto surfaces by using three-dimensional microfluidic systems.

Three-dimensional microfluidic systems were fabricated and used to pattern proteins and mammalian cells on a planar substrate. The three-dimensional topology of the microfluidic network in the stamp makes this technique a versatile one with which to pattern multiple types of proteins and cells in complex, discontinuous structures on a surface. The channel structure, formed by the stamp when it is in contact with the surface of the substrate, limits migration and growth of cells in the channels. With the channel structure in contact with the surface, the cells stop dividing once they form a confluent layer. Removal of the stamp permits the cells to spread and divide.