Kinetics of the helix-coil transition

Based on the Zimm-Bragg model we study cooperative helix-coil transition driven by a finite-speed change of temperature. There is an asymmetry between the coil-to-helix and helix-to-coil transition: the latter is displayed already for finite speeds, and takes shorter time than the former. This hysteresis effect has been observed experimentally, and it is explained here via quantifying system's stability in the vicinity of the critical temperature. A finite-speed cooling induces a non-equilibrium helical phase with the correlation length larger than in equilibrium. In this phase the characteristic length of the coiled domain and the non-equilibrium specific heat can display an anomalous response to temperature changes. Several pertinent experimental results on the kinetics helical biopolymers are discussed in detail.Comment: 6 pages, 8 figure

Identification of novel vascular targets in lung cancer

Background: Lung cancer remains the leading cause of cancer-related death, largely owing to the lack of effective treatments. A tumour vascular targeting strategy presents an attractive alternative; however, the molecular signature of the vasculature in lung cancer is poorly explored. This work aimed to identify novel tumour vascular targets in lung cancer. Methods: Enzymatic digestion of fresh tissue followed by endothelial capture with Ulex lectin-coated magnetic beads was used to isolate the endothelium from fresh tumour specimens of lung cancer patients. Endothelial isolates from the healthy and tumour lung tissue were subjected to whole human genome expression profiling using microarray technology. Results: Bioinformatics analysis identified tumour endothelial expression of angiogenic factors, matrix metalloproteases and cellsurface transmembrane proteins. Predicted novel tumour vascular targets were verified by RNA-seq, quantitative real-time PCR analysis and immunohistochemistry. Further detailed expression profiling of STEAP1 on 82 lung cancer patients confirmed STEAP1 as a novel target in the tumour vasculature. Functional analysis of STEAP1 using siRNA silencing implicates a role in endothelial cell migration and tube formation. Conclusions: The identification of cell-surface tumour endothelial markers in lung is of interest in therapeutic antibody and vaccine development

Altered electrophysiologic and pharmacologic response of smooth muscle cells on exposure to electrical fields generated by blood flow.

The flow of the blood past the vascular wall gives rise to an electrical potential. This field is calculated to have a periodic waveform with a transluminal peak-to-peak amplitude of approximately 1.35 V/m-1. Digital imaging fluorescent microscopy was used to measure changes in the membrane potentials of smooth muscle cells by following changes in the fluorescence of the potential sensitive dye, 3,3'-dipropyloxacarbocyanine iodide (di-O-C5[3]). The effect of the low level electrical field on the membrane potentials of cultured smooth muscle vascular cells was shown to cause a steady-state depolarization of approximately 10 mV. The degree of steady-state depolarization was shown to directly vary with the frequency of the applied field and the effect was not dependent on the presence of extracellular Ca+2 or Mg+2. These effects are though to be most consistent with an electroconformational coupling mechanism. The presence of this electrokinetic field was also shown to alter the electrophysiological response of smooth muscle cells treated with 5-hydroxytryptamine. Cells exposed concurrently to both 5-HT and the electrical field showed an increased membrane depolarization thus implying that the electrokinetic field may be important in both normal and pathologic cellular responses

Medical optics and biotechnology; (170.2655) Functional monitoring and imaging; (170.3660) Light propagation in tissues

Abstract: Using non-invasive, near-infrared spectroscopy we have previously reported optical signals measured at or around peripheral nerves in response to their stimulation. Such optical signals featured amplitudes on the order of 0.1% and peaked about 100 ms after peripheral nerve stimulation in human subjects. Here, we report a study of the spatial and spectral dependence of the optical signals induced by stimulation of the human median and sural nerves, and observe that these optical signals are: (1) unlikely due to either dilation or constriction of blood vessels, (2) not associated with capillary bed hemoglobin, (3) likely due to blood vessel(s) displacement, and (4) unlikely due to fiber-skin optical coupling effects. We conclude that the most probable origin of the optical response to peripheral nerve stimulation is from displacement of blood vessels within the optically probed volume, as a result of muscle twitch in adjacent areas