Direct periodic patterning of GaN-based light-emitting diodes by three-beam interference laser ablation

We report on the direct patterning of two-dimensional periodic structures in GaN-based light-emitting diodes (LEDs) through laser interference ablation for the fast and reliable fabrication of periodic micro-and nano-structures aimed at enhancing light output. Holes arranged in a two-dimensional hexagonal lattice array having an opening size of 500 nm, depth of 50 nm, and a periodicity of 1 mu m were directly formed by three-beam laser interference without photolithography or electron-beam lithography processes. The laser-patterned LEDs exhibit an enhancement in light output power of 20% compared to conventional LEDs having a flat top surface without degradation of electrical and optical properties of the top p-GaN layer and the active region, respectively.&nbsp

Erythropoietin promotes hair shaft growth in cultured human hair follicles and modulates hair growth in mice

Background: Recent studies have shown that erythropoietin (EPO)/erythropoietin receptor (EPOR) signaling exist in both human and mouse hair follicles (HFs). Objective: To investigate whether dermal papilla cells (DPCs) express functional EPOR and, if so, to investigate effects of EPO on hair shaft growth in cultured human scalp hair follicles and hair growth in mice. Methods: EPOR expression in DPCs and follicular keratinocytes was examined by RT-PCR and immunoblot. Phosphorylation of EPOR signaling pathway mediators by EPO treatment was examined by immunoblot. MTT assay was employed to check cell viability after EPO treatment. Hair shaft growth was measured in the absence or presence of EPO and matrix keratinocyte proliferation was examined by Ki-67 immunostaining in cultured hair follicles. Agarose beads containing EPO were implanted into dorsal skin of C57BL/6 mice to examine effects of EPO on hair growth in vivo. Results: EPOR mRNA and protein are expressed in cultured human DPCs. EPOR signaling pathway mediators such as EPOR and Akt are phosphorylated by EPO in DPCs. EPO significantly promoted the growth of DPCs and elongated hair shafts with increased proliferation of matrix keratinocytes in cultured human hair follicles. In addition, EPO not only promoted anagen induction from telogen but also prolonged anagen phase. Conclusions: EPO may modulate hair growth by stimulating DPCs that express functional EPOR. © 2010 Japanese Society for Investigative Dermatology.

Molecular epidemiology of extended-spectrum β-lactamase-producing <it>Escherichia coli</it> in the community and hospital in Korea: emergence of ST131 producing CTX-M-15

<p>Abstract</p> <p>Background</p> <p>The prevalence of extended-spectrum β-lactamase (ESBL)-producing <it>Escherichia coli</it> has been increased not only in the hospital but also in the community worldwide. This study was aimed to characterize ESBL- producing <it>E. coli</it> isolates and to investigate the molecular epidemiology of community isolates in comparison with hospital isolates at a single center in Korea.</p> <p>Methods</p> <p>A total of 142 ESBL-producing <it>E. coli</it> isolates were collected at Daejeon St Mary’s Hospital in Korea from January 2008 to September 2009. The ESBLs were characterized by PCR sequencing using specific primers. The genetic relatedness was determined by pulsed field gel electrophoresis (PFGE) and multilocus sequence typing (MLST).</p> <p>Results</p> <p>Of 142 isolates, 139 were positive for CTX-M type ESBLs; CTX-M-14 (n = 69, 49.6 %), CTX-M-15 (n = 53, 38.1 %) and both CTX-M-14 and -15 (n = 17, 12.2 %). CTX-M-14 and CTX-M-15 were detected in both community and hospital isolates whereas isolates producing both CTX-M14 and-15 were mainly identified in the hospital. CTX-M producing <it>E. coli</it> isolates were genetically heterogeneous, revealing 75 distinct PFGE types. By MLST, 21 distinctive STs including 5 major STs (ST131, ST405, ST38, ST10, and ST648) were identified. Major STs were distributed in both community and hospital isolates, and ST131 was the predominant clone regardless of the locations of acquisition. No specific major STs were confined to a single type of ESBLs. However, ST131 clones were significantly associated with CTX-M-15 and the majority of them were multidrug-resistant. Distinctively, we identified a hospital epidemic caused by the dissemination of an epidemic strain, ST131-PFGE type 10, characterized by multidrug resistance and co-producing both CTX-Ms with OXA-1 or TEM-1b.</p> <p>Conclusions</p> <p>The epidemiology of ESBL-producing <it>E. coli</it> is a complex and evolving phenomenon attributed to the horizontal transfer of genetic elements and clonal spread of major clones, predominantly ST131. The multidrug resistant ST131 clone producing CTX-M-15 has emerged as a major clone in both the community and hospital, suggesting the widespread of this epidemic clone in Korea.</p