Rapid 3D roll-up of gas-phase planar gold clusters and affinity and alienation for Mg and Ge: A theoretical study of MgGeAun (n=1-12) clusters.

A cluster is a special matter level above a single atom and between macroscopic and microscopic matter, and it is an important bridge to understanding the relationship between the structure and function of matter. Here, we perform a comprehensive theoretical study of 2D planar Aun (n = 1-12) clusters doped with both magnesium and germanium. Two interesting results are found, namely the rapid 3D "roll-up" structural growth of the GeMgAun (n = 1-12) cluster ground state isomers, and the relative "alienation" of the different sizes of the Aun (n = 1-12) cluster framework towards the Ge atom, and the relative "affinity" towards the Mg atom. This study will not only enrich the data on gold-based clusters but will also provide a simple and clear theoretical guide for the 3D structuring of planar clusters, i.e. the doping of different classes of "affinition" and "alienatation" atoms.

Systematic research on gallium atom-doped neutral small- and medium-sized gas-phase magnesium clusters: A DFT study of GaMgn (n=2-12) clusters.

Structure, stability, charge transfer, chemical bonding, and spectroscopic properties of Ga atom-doped neutral Mgn (n = 2-12) clusters have been systematically investigated by CALYPSO and density functional theory. All cluster structures are based on "tetrahedral" and "yurt-like" growth except for GaMg2. The ground state isomer of GaMg8 with high symmetry structure is predicted to be the best-fit candidate for the "magic" cluster because of its excellent stability. Natural bond orbital calculations reveal that Ga and Mg atoms play the role of electron acceptor and donor in all ground state isomers, while the orbitals in both Ga and Mg are sp-hybridized. Most importantly, chemical bonding studies based on atom-in-molecular theory have shown that the lowest-energy state of GaMg4 is so special, in that it has not only the critical size for the appearance of Mg-Mg covalent bonds, but also the only cluster that has both Ga-Mg covalent and non-covalent bonds. Finally, theoretical calculations of IR and Raman spectra of all ground state isomers indicate that the spectra of these clusters are observable in the low-frequency band, and thus they can be identified by spectroscopic experiments. Furthermore, the bond heterogeneity of the Ga-Mg in the GaMg4 ground state isomer has also been specifically investigated, including the fixed GaMg4 structure with Mg atoms added in different directions, as well as ab initio molecular dynamics sampling at different temperatures.

Searching new structures of beryllium-doped in small-sized magnesium clusters: Be2 Mgn Q (Q = 0, -1; n = 1-11) clusters DFT study.

Using CALYPSO method to search new structures of neutral and anionic beryllium-doped magnesium clusters followed by density functional theory (DFT) calculations, an extensive study of the structures, electronic and spectral properties of Be2 Mgn Q (Q = 0, -1; n = 2-11) clusters is performed. Based on the structural optimization, it is found that the Be2 Mgn Q (Q = 0, -1) clusters are shown by tetrahedral-based geometries at n = 2-6 and tower-like-based geometries at n = 7-11. The calculations of stability indicate that Be2 Mg5 Q=0 , Be2 Mg5 Q=-1 , and Be2 Mg8 Q=-1 clusters are "magic" clusters with high stability. The NCP shows that the charges are transferred from Mg atoms to Be atoms. The s- and p-orbitals interactions of Mg and Be atoms are main responsible for their NEC. In particular, chemical bond analysis including molecular orbitals (MOs) and chemical bonding composition for magic clusters to further study their stability. The results confirmed that the high stability of these clusters is due to the interactions between the Be atom and the Mg5 or Mg8 host. Finally, theoretical calculations of infrared and Raman spectra of the ground state of Be2 Mgn Q (Q = 0, -1; n = 1-11) clusters were performed, which will be absolutely useful for future experiments to identify these clusters.

Bone resorption deficiency affects tooth root development in RANKL mutant mice due to attenuated IGF-1 signaling in radicular odontoblasts.

The tooth root is essential for normal tooth physiological function. Studies on mice with mutations or targeted gene deletions revealed that osteoclasts (OCs) play an important role in tooth root development. However, knowledge on the cellular and molecular mechanism underlying how OCs mediate root formation is limited. During bone formation, growth factors (e.g. Insulin-like growth factor-1, IGF-1) liberated from bone matrix by osteoclastic bone resorption stimulate osteoblast differentiation. Thus, we hypothesize that OC-osteoblast coupling may also apply to OC-odontoblast coupling; therefore OCs may have a direct impact on odontoblast differentiation through the release of growth factor(s) from bone matrix, and consequently regulate tooth root formation. To test this hypothesis, we used a receptor activator of NF-κB ligand (RANKL) knockout mouse model in which OC differentiation and function was entirely blocked. We found that molar root formation and tooth eruption were defective in RANKL-/- mice. Disrupted elongation and disorganization of Hertwig's epithelial root sheath (HERS) was observed in RANKL-/- mice. Reduced expression of nuclear factor I C (NFIC), osterix, and dentin sialoprotein, markers essential for radicular (root) odontogenic cell differentiation indicated that odontoblast differentiation was disrupted in RANKL deficient mice likely contributing to the defect in root formation. Moreover, down-regulation of IGF/AKT/mTOR activity in odontoblast indicated that IGF signaling transduction in odontoblasts of the mutant mice was impaired. Treating odontoblast cells in vitro with conditioned medium from RANKL-/- OCs cultured on bone slices resulted in inhibition of odontoblast differentiation. Moreover, depletion of IGF-1 in bone resorption-conditioned medium (BRCM) from wild-type (WT) OC significantly compromised the ability of WT osteoclastic BRCM to induce odontoblast differentiation while addition of IGF-1 into RANKL-/- osteoclastic BRCM rescued impaired odontoblast differentiation, confirming that root and eruption defect in RANKL deficiency mice may result from failure of releasing of IGF-1 from bone matrix through OC bone resorption. These results suggest that OCs are important for odontoblast differentiation and tooth root formation, possibly through IGF/AKT/mTOR signaling mediated by cell-bone matrix interaction. These findings provide significant insights into regulatory mechanism of tooth root development, and also lay the foundation for root regeneration studies.

The expression of Cullin1 is increased in renal cell carcinoma and promotes cancer cell proliferation, migration, and invasion.

Cullin1 (Cul1) is a scaffold protein of the ubiquitin E3 ligase Skp1/Cullin1/Rbx1/F-box protein complex, which ubiquitinates a broad range of proteins involved in cell-cycle progression, signal transduction, and transcription. To investigate the role of Cul1 in the development of renal cell carcinoma (RCC), we evaluated the Cul1 expression by immunohistochemistry using a tissue microarray (TMA) containing 307 cases of RCC tissues and 34 normal renal tissues. The Cul1 expression was increased significantly in RCC and was correlated with renal carcinoma histology grade (P = 0.007), tumor size (P = 0.013), and pT status (P = 0.023). Also, we found that silencing of Cul1 leads to increased expression of p21 and p27 that could inhibit the cyclin D1 and cyclin E2 expressions and arrest cell cycle at the G1 phase. Furthermore, knockdown of Cul1 inhibits RCC cell migration and invasion abilities by up-regulating the expression of TIMP-1 which could inhibit the expression of MMP-9. Finally, using bioluminescence imaging, we found that Cul1 knockdown significantly reduced the tumor growth in vivo. Cul1 may constitute a potential therapeutic target in RCC.

Randomized prospective trial of tubeless versus conventional minimally invasive percutaneous nephrolithotomy.

PURPOSE: To evaluate the effectiveness and safety of minimally invasive percutaneous nephrolithotomy (mPCNL) without nephrostomy drainage tubes. METHODS: We prospectively enrolled 32 eligible patients with kidney stones at our hospital. Patients were randomly assigned to a conventional mPCNL group (ureteric Double-J stents and nephrostomy drainage tubes) or a tubeless mPCNL group (ureteric catheter but no drainage tubes). A single experienced surgeon performed all operations. RESULTS: At baseline, the two groups had similar age, maximum stone diameter, and gender distribution. There were no significant differences in operation time, presence of postoperative fever, stone clearance, and level of postoperative serum hemoglobin. However, the tubeless mPCNL group had significantly shorter hospital stays (3 vs. 4 days, p = 0.032) and significantly less back pain (5 patients vs. 14 patients, p = 0.003) than the conventional mPCNL group. CONCLUSIONS: No significant differences were found between conventional and tubeless mPCNL in safety issues and stone clearance rate. However, patients treated with tubeless mPCNL had shorter hospitalization stays and were less likely to experience back pain.