Differential inhibition of postnatal brain,spinal cord and body growth by a growth hormone antagonist

Background  

Growth hormone (GH) plays an incompletely understood role in the development of the central nervous system (CNS). In this study, we use transgenic mice expressing a growth hormone antagonist (GHA) to explore the role of GH in regulating postnatal brain, spinal cord and body growth into adulthood. The GHA transgene encodes a protein that inhibits the binding of GH to its receptor, specifically antagonizing the trophic effects of endogenous GH.     

Immobilization of functional light antenna structures derived from the filamentous green bacterium Chloroflexus aurantiacus

The integration of highly efficient, natural photosynthetic light antenna structures into engineered systems while their biophotonic capabilities are maintained has been an elusive goal in the design of biohybrid photonic devices. In this study, we report a novel technique to covalently immobilize nanoscaled bacterial light antenna structures known as chlorosomes from Chloroflexus aurantiacus on both conductive and nonconductive glass while their energy transducing functionality was maintained. Chlorosomes without their reaction centers (RCs) were covalently immobilized on 3-aminoproyltriethoxysilane (APTES) treated surfaces using a glutaraldehyde linker. AFM techniques verified that the chlorosomes maintained their native ellipsoidal ultrastructure upon immobilization. Results from absorbance and fluorescence spectral analysis (where the Stokes shift to 808/810 nm was observed upon 470 nm blue light excitation) in conjunction with confocal microscopy confirm that the functional integrity of immobilized chlorosomes was also preserved. In addition, experiments with electrochemical impedance spectroscopy (EIS) suggested that the presence of chlorosomes in the electrical double layer of the electrode enhanced the electron transfer capacity of the electrochemical cell. Further, chronoamperometric studies suggested that the reduced form of the Bchl- c pigments found within the chlorosome modulate the conduction properties of the electrochemical cell, where the oxidized form of Bchl- c pigments impeded any current transduction at a bias of 0.4 V within the electrochemical cell. The results therefore demonstrate that the intact chlorosomes can be successfully immobilized while their biophotonic transduction capabilities are preserved through the immobilization process. These findings indicate that it is feasible to design biophotonic devices incorporating fully functional light antenna structures, which may offer significant performance enhancements to current silicon-based photonic devices for diverse technological applications ranging from CCD devices used in retinal implants to terrestrial and space fuel cell applications.     

Effect of three-body forces on the lattice dynamics of noble metals

A simple method to generate an effective electron-ion interaction pseudopotential from the energy wave number characteristic obtained by first principles calculations has been suggested. This effective potential has been used, in third order perturbation, to study the effect of three-body forces on the lattice dynamics of noble metals. It is found that three-body forces, in these metals, do play an important role. The inclusion of such three-body forces appreciably improves the agreement between the experimental and theoretical phonon dispersion curves.     

Isolation of plasma from whole blood using planar microfilters for lab-on-a-chip applications

Researchers are actively developing devices for the microanalysis of complex fluids, such as blood. These devices have the potential to revolutionize biological analysis in a manner parallel to the computer chip by providing very high throughput screening of complex samples and massively parallel bioanalytical capabilities. A necessary step performed in clinical chemistry is the isolation of plasma from whole blood, and effective sample preparation techniques are needed for the development of miniaturized clinical diagnostic devices. This study demonstrates the use of passive, operating entirely on capillary action, transverse-flow microfilter devices for the microfluidic isolation of plasma from whole blood. Using these planar microfilters, blood can be controllably fractionated with minimal cell lysis. A characterization of the device performance reveals that plasma filter flux is dependent upon the wall shear rate of blood in the filtration channel, and this result is consistent with macroscale blood filtration using microporous membranes. Also, an innovative microfluidic layout is demonstrated that extends device operation time via capillary action from seconds to minutes. Efficiency of these microfilters is approximately three times higher than the separation efficiencies predicted for microporous membranes under similar conditions. As such, the application of the microscale blood filtration designs used in this study may have broad implications in the design of lab-on-a-chip devices, as well as the field of separation science.