High Cleavage Efficiency of a 2A Peptide Derived from Porcine Teschovirus-1 in Human Cell Lines, Zebrafish and Mice

When expression of more than one gene is required in cells, bicistronic or multicistronic expression vectors have been used. Among various strategies employed to construct bicistronic or multicistronic vectors, an internal ribosomal entry site (IRES) has been widely used. Due to the large size and difference in expression levels between genes before and after IRES, however, a new strategy was required to replace IRES. A self-cleaving 2A peptide could be a good candidate to replace IRES because of its small size and high cleavage efficiency between genes upstream and downstream of the 2A peptide. Despite the advantages of the 2A peptides, its use is not widespread because (i) there are no publicly available cloning vectors harboring a 2A peptide gene and (ii) comprehensive comparison of cleavage efficiency among various 2A peptides reported to date has not been performed in different contexts. Here, we generated four expression plasmids each harboring different 2A peptides derived from the foot-and-mouth disease virus, equine rhinitis A virus, Thosea asigna virus and porcine teschovirus-1, respectively, and evaluated their cleavage efficiency in three commonly used human cell lines, zebrafish embryos and adult mice. Western blotting and confocal microscopic analyses revealed that among the four 2As, the one derived from porcine teschovirus-1 (P2A) has the highest cleavage efficiency in all the contexts examined. We anticipate that the 2A-harboring cloning vectors we generated and the highest efficiency of the P2A peptide we demonstrated would help biomedical researchers easily adopt the 2A technology when bicistronic or multicistronic expression is required

Strong optical modulation of surface plasmon polaritons in metal/semiconductor nanostructures

We demonstrate strong modulation of the transmission around the surface plasmon polariton (SPP) resonance in metal/semiconductor hybrid nanostructures based on Ag film on top of InGaAs. The change in the real and imaginary parts of the refractive index due to photoexcited carriers in InGaAs generates a shift in the SPP resonance and enhanced transmission near the SPP resonance. Temporal evolution of the complex refractive index was traced by comparing the transient transmission with finite-difference time-domain (FDTD) simulations

Highly-Sensitive Plasmonic Nano-Ring Transistor for Monolithic Terahertz Active Antenna

We report a highly-sensitive plasmonic nano-ring transistor for monolithic terahertz (THz) active antenna. By designing an ultimate asymmetric transistor on a metal-gate structure, more enhanced (180 times) channel charge asymmetry has been obtained in comparison with a bar-type asymmetric transistor of our previous work. In addition, by exploiting ring-type transistor itself as a monolithic circular active antenna, which is designed for a 0.12-THz resonance frequency, we experimentally demonstrated the highly-enhanced responsivity (Rv) > 1 kV/W (x 5) and reduced noise-equivalent power (NEP) < 10 pW/Hz0.5 (x 1/10)

Broadband Surface Plasmon Lasing in One-dimensional Metallic Gratings on Semiconductor

We report surface plasmon (SP) lasing in metal/semiconductor nanostructures, where one-dimensional periodic silver slit gratings are placed on top of an InGaAsP layer. The SP nature of the lasing is confirmed from the emission wavelength governed by the grating period, polarization analysis, spatial coherence, and comparison with the linear transmission. The excellent performance of the device as an SP source is demonstrated by its tunable emission in the 400-nm-wide telecom wavelength band at room temperature. We show that the stimulated emission enhanced by the Purcell effect enables successful SP lasing at high energies above the gap energy of the gain. We also discuss the dependence of the lasing efficiency on temperature, grating dimension, and type of metal

The Clinicopathological and Prognostic Significance of the Gross Classification of Hepatocellular Carcinoma

Background We aimed to determine the clinicopathological significance of the gross classification of hepatocellular carcinoma (HCC) according to the Korean Liver Cancer Association (KLCA) guidelines. Methods A retrospective analysis was performed on 242 cases of consecutively resected solitary primary HCC between 2003 and 2012 at Seoul National University Bundang Hospital. The gross classification (vaguely nodular [VN], expanding nodular [EN], multinodular confluent [MC], nodular with perinodular extension [NP], and infiltrative [INF]) was reviewed for all cases, and were correlated with various clinicopathological features and the expression status of “stemness”-related (cytokeratin 19 [CK19], epithelial cell adhesion molecule [EpCAM]), and epithelial-mesenchymal transition (EMT)–related (urokinase plasminogen activator receptor [uPAR] and Ezrin) markers. Results Significant differences were seen in overall survival (p=.015) and disease-free survival (p = .034) according to the gross classification; INF type showed the worst prognosis while VN and EN types were more favorable. When the gross types were simplified into two groups, type 2 HCCs (MC/NP/INF) were more frequently larger and poorly differentiated, and showed more frequent microvascular and portal venous invasion, intratumoral fibrous stroma and higher pT stages compared to type 1 HCCs (EN/VN) (p<.05, all). CK19, EpCAM, uPAR, and ezrin expression was more frequently seen in type 2 HCCs (p<.05, all). Gross classification was an independent predictor of both overall and disease-free survival by multivariate analysis (overall survival: p=.030; hazard ratio, 4.118; 95% confidence interval, 1.142 to 14.844; disease-free survival: p=.016; hazard ratio, 1.617; 95% confidence interval, 1.092 to 2.394). Conclusions The gross classification of HCC had significant prognostic value and type 2 HCCs were associated with clinicopathological features of aggressive behavior, increased expression of “stemness”- and EMT-related markers, and decreased survival