Uniform Asymptotics of Orthogonal Polynomials Arising from Coherent States

In this paper, we study a family of orthogonal polynomials $\{\phi_n(z)\}$ arising from nonlinear coherent states in quantum optics. Based on the three-term recurrence relation only, we obtain a uniform asymptotic expansion of $\phi_n(z)$ as the polynomial degree $n$ tends to infinity. Our asymptotic results suggest that the weight function associated with the polynomials has an unusual singularity, which has never appeared for orthogonal polynomials in the Askey scheme. Our main technique is the Wang and Wong's difference equation method. In addition, the limiting zero distribution of the polynomials $\phi_n(z)$ is provided

MicroRNA-520b Inhibits Growth of Hepatoma Cells by Targeting MEKK2 and Cyclin D1

Growing evidence indicates that the deregulation of microRNAs (miRNAs) contributes to the tumorigenesis. We previously revealed that microRNA-520b (miR-520b) was involved in the complement attack and migration of breast cancer cells. In this report, we show that miR-520b is an important miRNA in the development of hepatocellular carcinoma (HCC). Our data showed that the expression levels of miR-520b were significantly reduced in clinical HCC tissues and hepatoma cell lines. We observed that the introduction of miR-520b dramatically suppressed the growth of hepatoma cells by colony formation assays, 5-ethynyl-2-deoxyuridine (EdU) incorporation assays and 3-(4,5- dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assays. Moreover, ectopic expression of miR-520b was able to inhibit the growth of hepatoma cells in nude mice. Further studies revealed that the mitogen-activated protein kinase kinase kinase 2 (MEKK2) and cyclin D1 were two of direct target genes of miR-520b. Silencing of MEKK2 or cyclin D1 was able to inhibit the growth of hepatoma cells in vitro and in vivo, which is consistent with the effect of miR-520b overexpression on the growth of hepatoma cells. In addition, miR-520b significantly decreased the phosphorylation levels of c-Jun N-terminal kinase (p-JNK, a downstream effector of MEKK2) or retinoblastoma (p-Rb, a downstream effector of cyclin D1). In conclusion, miR-520b is able to inhibit the growth of hepatoma cells by targeting MEKK2 or cyclin D1 in vitro and in vivo. Our findings provide new insights into the role of miR-520b in the development of HCC, and implicate the potential application of miR-520b in cancer therapy

Breast-cancer-secreted miR-122 reprograms glucose metabolism in premetastatic niche to promote metastasis

Reprogrammed glucose metabolism as a result of increased glycolysis and glucose uptake is a hallmark of cancer. Here we show that cancer cells can suppress glucose uptake by non-tumour cells in the pre-metastatic niche, by secreting vesicles that carry high levels of the miR-122 microRNA. High miR-122 levels in the circulation have been associated with metastasis in breast cancer patients and we show that cancer-cell-secreted miR-122 facilitates metastasis by increasing nutrient availability in the pre-metastatic niche. Mechanistically cancer-cell-derived miR-122 suppresses glucose uptake by niche cells in vitro and in vivo by downregulating the glycolytic enzyme pyruvate kinase (PKM). In vivo inhibition of miR-122 restores glucose uptake in distant organs, including brain and lungs, and decreases the incidence of metastasis. These results demonstrate that by modifying glucose utilization by recipient pre-metastatic niche cells, cancer-derived extracellular miR-122 is able to reprogram systemic energy metabolism to facilitate disease progression

Distinct Aging Effects on Motion Repulsion and Surround Suppression in Humans

Elderly exhibit accumulating deficits in visual motion perception, which is critical for humans to interact with their environment. Previous studies have suggested that aging generally reduces neuronal inhibition in the visual system. Here, we investigated how aging affects the local intra-cortical inhibition using a motion direction discrimination task based on the motion repulsion phenomenon. Motion repulsion refers to the phenomenon by which observers overestimate the perceived angle when two superimposed dot patterns are moving at an acute angle. The misperception has been interpreted as local mutual inhibition between nearby direction-tuned neurons within the same cortical area. We found that elderly exhibited much stronger motion repulsion than young adults. We then compared this effect to how aging affects the global inter-cortical inhibition by adopting the surround suppression paradigm previously used by Betts et al. (2005). We found that elderly showed less change in the discrimination threshold when the size of a high-contrast drifting Gabor was increased, indicating reduced surround suppression compared to young adults. Our results indicate that aging may not always lead to a decrease of neuronal inhibition in the visual system. These distinct effects of aging on inhibitory functions might be one of the reasons that elderly people often exhibit deficits of motion perception in a real-world situation

The heat shock protein 70 gene as a new alternative molecular marker for the taxonomic identification of Streptomyces strains

Abstract With the developments in taxonomy, the classically used highly conserved 16S rRNA molecular marker has shown some disadvantages among closely related species. For further taxonomic studies of the prokaryotes, specific PCR primers were designed from two conserved regions in the amino acid sequences of the 70-kDa heat shock protein sourced from 20 different genera in actinomycetes. These were used for the amplification of the hsp70 genes in 16 Streptomyces strains. Then, we investigated the phylogenetic relationships among these Streptomyces strains and compared the tree topology based on the hsp70 gene with those based on the previously used markers (16S rRNA and gyrB). To our knowledge, this is the first use of the hsp70 gene as a molecular marker for the taxonomic identification of Streptomyces

Distinct Aging Effects on Motion Repulsion and Surround Suppression in Humans

Elderly exhibit accumulating deficits in visual motion perception, which is critical for humans to interact with their environment. Previous studies have suggested that aging generally reduces neuronal inhibition in the visual system. Here, we investigated how aging affects the local intra-cortical inhibition using a motion direction discrimination task based on the motion repulsion phenomenon. Motion repulsion refers to the phenomenon by which observers overestimate the perceived angle when two superimposed dot patterns are moving at an acute angle. The misperception has been interpreted as local mutual inhibition between nearby direction-tuned neurons within the same cortical area. We found that elderly exhibited much stronger motion repulsion than young adults. We then compared this effect to how aging affects the global inter-cortical inhibition by adopting the surround suppression paradigm previously used by Betts et al. (2005). We found that elderly showed less change in the discrimination threshold when the size of a high-contrast drifting Gabor was increased, indicating reduced surround suppression compared to young adults. Our results indicate that aging may not always lead to a decrease of neuronal inhibition in the visual system. These distinct effects of aging on inhibitory functions might be one of the reasons that elderly people often exhibit deficits of motion perception in a real-world situation.</p