Sine-wave current for efficient and safe in vivo gene transfer.

Recently, electro-gene transfer has become a powerful tool to enhance the efficiency of gene expression in different organs and particularly in muscle, which provides efficient secretion of therapeutic proteins into the circulation. However, its toxicity, owing to the high field strengths of conventional direct current (DC) square-waves, should be taken into account and should be minimized if electroporation is to be used routinely for the treatment of human diseases. In this study, we demonstrate that efficient in vivo gene transfer could be safely achieved using pulses of alternating current sine-waves (ACSWs) with a frequency of 60 Hz. Importantly, the field strength was decreased to as low as 20 V/cm and the efficiency of muscle gene transfer increased more than tenfold and showed less toxicity than with conventional DC square-wave pulses. Using ACSW pulses to transfer human clotting factor IX (hFIX) plasmid into muscle, we observed significant phenotypic correction in mice with hemophilia B.

Design and preliminary evaluation of a portable device for the measurement of bioimpedance spectroscopy.

Portable bioimpedance spectroscopy (BIS) devices are of great value for monitoring the pathological status of biological tissues in clinical and home environments. The two traditional techniques for measuring complex bioimpedance, the bridge method and quadrature demodulation method, are either time-consuming or often associated with high cost, high power consumption, and large board space, and therefore are not ideally suitable for designing a portable device for BIS measurement. This paper describes a novel design of a portable BIS device based on the magnitude-ratio and phase-difference detection method and its implementation using the newest generation of analog electronic products which greatly decrease the complexity of both hardware and software. In order to improve the accuracy of the device, a three-reference calibration algorithm was applied. Experimental sweep-frequency measurements on RC circuits were carried out to preliminarily evaluate the performances of the device. The results obtained by the device were found to be in good agreement with the results measured by a commercial impedance analyzer HP4194, with an overall mean error of 0.014% in magnitude and 0.136 degrees in phase over a frequency range of 20 kHz to 1 MHz.