Growth mechanisms in molecular beam epitaxy for GaN-(In,Ga)N core-shell nanowires emitting in the green spectral range

Using molecular beam epitaxy, we demonstrate the growth of (In,Ga)N shells emitting in the green spectral range around very thin (35 nm diameter) GaN core nanowires. These GaN nanowires are obtained by self-assembled growth on TiN. We present a qualitative shell growth model accounting for both the three-dimensional nature of the nanostructures as well as the directionality of the atomic fluxes. This model allows us, on the one hand, to optimise the conditions for high and homogeneous In incorporation and, on the other hand, to explain the influence of changes in the growth conditions on the sample morphology and In content. Specifically, the impact of the V/III and In/Ga flux ratios, the rotation speed and the rotation direction are investigated. Notably, with In acting as surfactant, the ternary (In,Ga)N shells are much more homogeneous in thickness along the NW length than their binary GaN counterparts

Chemerin and Cancer

Chemerin is a multifunctional adipokine with established roles in inflammation, adipogenesis and glucose homeostasis. Increasing evidence suggest an important function of chemerin in cancer. Chemerin’s main cellular receptors, chemokine-like receptor 1 (CMKLR1), G-protein coupled receptor 1 (GPR1) and C-C chemokine receptor-like 2 (CCRL2) are expressed in most normal and tumor tissues. Chemerin’s role in cancer is considered controversial, since it is able to exert both anti-tumoral and tumor-promoting effects, which are mediated by different mechanisms like recruiting innate immune defenses or activation of endothelial angiogenesis. For this review article, original research articles on the role of chemerin and its receptors in cancer were considered, which are listed in the PubMed database. Additionally, we included meta-analyses of publicly accessible DNA microarray data to elucidate the association of expression of chemerin and its receptors in tumor tissues with patients’ survival

Sequential directional deposition of one-sided (In,Ga)N shells on GaN nanowires by molecular beam epitaxy

Capitalizing on the directed nature of the atomic fluxes in molecular beam epitaxy, we propose and demonstrate the sequential directional deposition of lateral (In,Ga)N shells on GaN nanowires. In this approach, a sub-monolayer thickness of each constituent atomic species, i.e. Ga, In, and N, is deposited subsequently from the same direction by rotating the sample and operating the shutters accordingly. Using multiple iterations of this process, we achieve the growth of homogeneous shells on a single side facet of the nanowires. For higher In content and thus lattice mismatch, we observe a strain-induced bending of the nanowire heterostructures. The incorporation of In and the resulting emission spectra are systematically investigated as a function of both the growth temperature and the In/Ga flux ratio

The Complex Roles of Adipokines in Polycystic Ovary Syndrome and Endometriosis

Polycystic ovary syndrome (PCOS) and endometriosis are frequent diseases of the female reproductive tract causing high morbidity as they can significantly affect fertility and quality of life. Adipokines are pleiotropic signaling molecules secreted by white or brown adipose tissues with a central role in energy metabolism. More recently, their involvement in PCOS and endometriosis has been demonstrated. In this review article, we provide an update on the role of adipokines in both diseases and summarize previous findings. We also address the results of multi-omics approaches in adipokine research to examine the role of single nucleotide polymorphisms (SNPs) in genes coding for adipokines and their receptors, the secretome of adipocytes and to identify epigenetic alterations of adipokine genes that might be conferred from mother to child. Finally, we address novel data on the role of brown adipose tissue (BAT), which seems to have notable effects on PCOS. For this review, original research articles on adipokine actions in PCOS and endometriosis are considered, which are listed in the PubMed database

Estrogen receptor β is associated with expression of cancer associated genes and survival in ovarian cancer

BackgroundIn ovarian cancer, the role of estrogen receptors (ERs), particularly of ER, being suggested as tumor suppressor in breast and prostate cancer, remains unclear. We examined the expression of nuclear and cytoplasmic ER in ovarian cancer and correlated it with expression of ovarian cancer markers CA125, CEA and CA72-4, steroid hormone receptors ER and PR, cancer-associated genes EGFR, p53, HER2 and proliferation marker Ki-67. Additionally we examined to what extent expression of ER and the other proteins affects survival of ovarian cancer patients.MethodsWe established a tissue microarray from 171 ovarian cancer patients and performed immunohistochemical analyses of the mentioned proteins.ResultsNuclear ER was detected in 47.31% of the ovarian cancer tissues and cytoplasmic expression of this receptor was observed in 23.08%. Nuclear expression of ER was significantly decreased in the G3 subgroup compared to better differentiated cancers (p<0.01) and correlated with ovarian cancer markers CEA (95% CI 0.1598-0.4465; p<0.0001) and CA72-4 (95% CI 0.05953-0.3616; p<0.01). Cytoplasmic ER expression correlated with EGFR levels (95% CI 0.1059-0.4049; p<0.001). ER expression was associated with expression of CA125 and PR. Overall survival of patients with tumors expressing cytoplasmic ER was significant longer compared to those with ER-negative ovarian cancer (chi-square statistic of the log-rank, p<0.05). Progression-free survival was dependent on expression of PR (chi-square statistic of the log-rank, p<0.05) and Ki-67 (p=0.05).ConclusionsOur data suggest an important, but distinct role of nuclear and cytoplasmic ER expression in ovarian cancer and encourage further studies on its role in this cancer entity

Role of Estrogen Receptor β, G-Protein Coupled Estrogen Receptor and Estrogen-Related Receptors in Endometrial and Ovarian Cancer

Ovarian and endometrial cancers are affected by estrogens and their receptors. It has been long known that in different types of cancers, estrogens activate tumor cell proliferation via estrogen receptor α (ERα). In contrast, the role of ERs discovered later, including ERβ and G-protein-coupled ER (GPER1), in cancer is less well understood, but the current state of knowledge indicates them to have a considerable impact on both cancer development and progression. Moreover, estrogen related receptors (ERRs) have been reported to affect pathobiology of many tumor types. This article provides a summary and update of the current findings on the role of ERβ, GPER1, and ERRs in ovarian and endometrial cancer. For this purpose, original research articles on the role of ERβ, GPER1, and ERRs in ovarian and endometrial cancers listed in the PubMed database have been reviewed

GPER-1 acts as a tumor suppressor in ovarian cancer

Background: It is known that the new membrane-bound estrogen receptor GPER-1 acts suppressive in breast cancer cells and its expression decreases during disease progression. This study was conducted to evaluate the GPER-1 expression in ovarian cancer and its correlation with progression. Its function was tested in vitro in ovarian cancer cells. PATIENTS AND METHODS: GPER-1 expression was analyzed by immunohistochemistry in 35 benign ovarian tumors, 35 tumors of low-malignant potential and in 124 ovarian cancers. GPER-1 expression was correlated to the prospectively evaluated disease-free survival of ovarian cancer patients. We also tested GPER-1 expression in ovarian cancer cells and the effect of GPER-1 stimulation on cell growth. RESULTS: GPER-1 expression was significantly lower in ovarian cancer tissue than in benign and low-malignant ovarian tumors. GPER-1 expression was observed in 83.1% of malignant tumors and was higher in early stage cancers and tumors with high histological differentiation. GPER-1 expression was associated with favourable clinical outcome. The difference in 2-year disease-free survival by GPER-1 expression was significant, 28.6% for GPER-1 negative and 59.2% for GPER-1 positive cases (p = 0.002). GPER-1 expression was observed in SKOV-3 and OVCAR-3 ovarian cancer cell lines. G-1, a selective GPER-1 agonist, suppressed proliferation of the two cell types via inhibition of cell cycle progression in G2/M phase and stimulation of caspase-dependent apoptosis. The blockade in G2/M phase was associated with increased expression of cyclin B1 and Cdc2 and phosphorylation of histone 3. CONCLUSION: GPER-1 emerges as a new tumor suppressor with unsuspected therapeutic potential for ovarian cancer

Chemerin and Chemokine-like Receptor 1 Expression in Ovarian Cancer Associates with Proteins Involved in Estrogen Signaling

Chemerin, a pleiotropic adipokine coded by the RARRES2 gene, has been reported to affect the pathophysiology of various cancer entities. To further approach the role of this adipokine in ovarian cancer (OC), intratumoral protein levels of chemerin and its receptor chemokine-like receptor 1 (CMKLR1) were examined by immunohistochemistry analyzing tissue microarrays with tumor samples from 208 OC patients. Since chemerin has been reported to affect the female reproductive system, associations with proteins involved in steroid hormone signaling were analyzed. Additionally, correlations with ovarian cancer markers, cancer-related proteins, and survival of OC patients were examined. A positive correlation of chemerin and CMKLR1 protein levels in OC (Spearman’s rho = 0.6, p < 0.0001) was observed. Chemerin staining intensity was strongly associated with the expression of progesterone receptor (PR) (Spearman´s rho = 0.79, p < 0.0001). Both chemerin and CMKLR1 proteins positively correlated with estrogen receptor β (ERβ) and estrogen-related receptors. Neither chemerin nor the CMKLR1 protein level was associated with the survival of OC patients. At the mRNA level, in silico analysis revealed low RARRES2 and high CMKLR1 expression associated with longer overall survival. The results of our correlation analyses suggested the previously reported interaction of chemerin and estrogen signaling to be present in OC tissue. Further studies are needed to elucidate to which extent this interaction might affect OC development and progression

X-ray scattering study of GaN nanowires grown on Ti/Al2_{2}O3_{3} by molecular beam epitaxy

GaN nanowires (NWs) grown by molecular beam epitaxy on Ti films sputtered on Al$_{2}$O$_{3}$ are studied by X-ray diffraction (XRD) and grazing incidence small-angle X-ray scattering (GISAXS). XRD, performed both in symmetric Bragg reflection and at grazing incidence, reveals Ti, Ti$_{3}$O, Ti$_{3}$Al, and TiO$_x$N$_y$ crystallites with in-plane and out-of-plane lattice parameters intermediate between those of Al$_{2}$O$_{3}$ and GaN. These topotaxial crystallites in Ti film, formed due to interfacial reactions and N exposure, possess fairly little misorientation with respect to Al$_{2}$O$_{3}$. As a result, GaN NWs grow on the top TiN layer possessing a high degree of epitaxial orientation with respect to the substrate. The measured GISAXS intensity distributions are modeled by the Monte Carlo method taking into account the orientational distributions of NWs, a variety of their cross-sectional shapes and sizes, and roughness of their side facets. The cross-sectional size distributions of the NWs and the relative fractions of $(1\bar{1}00)$ and $(11\bar{2}0)$ side facets are determined