A newly-developed metal artifact reduction algorithm improves the visibility of oral cavity lesions on 320-MDCT volume scans

PurposeTo investigate whether a newly-developed single-energy metal artifact reduction (SEMAR) algorithm applied to images acquired on a 320-MDCT volume scanner reduces image artifacts from dental metal.MethodsWe inserted the lower right teeth covered with a dental metal alloy and crown in a skull phantom and performed single-volume scanning on a second-generation 320-MDCT scanner. A 12-mm diameter spherical lesion was placed either close to or far from the dental metal. The tube voltage and current were 120 kVp and 80 or 155 mA, respectively. Images were reconstructed with filtered back projection (FBP) or iterative reconstruction (IR), with or without SEMAR. We calculated the signal-to-artifact ratios (SAR) to quantify the visibility of the lesion. Two radiologists inspected 96 images (48 with lesion and 48 without) for the presence or absence of the lesion using a 5-point ordinal scale (1 = definitely absent to 5 = definitely present).ResultsOn images reconstructed with FPB and IR with SEMAR, streak artifacts from the dental metal were reduced substantially compared to images without SEMAR. At 155 mA with the lesion near the dental metal, the SARs were better on FBP and IR images (FBP: 1.7 and 0.5 with and without SEMAR, respectively; IR: 1.6 and 0.9 with and without SEMAR, respectively). The observer visual scores improved with SEMAR (FBP: 4.2 and 3.2 with and without SEMAR, respectively; IR: 4.2 and 3.0).ConclusionThe SEMAR algorithm reduces dental metal artifacts and improves lesion detectability and image quality in patients with oral cavity lesions.     

Discovery of human autophagy initiation kinase ULK1 inhibitors by multi-directional in silico screening strategies

Autophagy is a self-catabolic mechanism employed by cancer cells to acquire nutrients and energy in times of stress conditions, thereby leading to its progression and survival. Thus, autophagy inhibition has emerged as a new paradigm in the area of cancer treatment. Here, we leverage multi-dimensional screening campaigns aim to identify potent inhibitors against an early and an essential autophagic kinase, ULK1 from DrugBank database. In particular, receptor-based hypothesis, pharmacophore hypothesis, e-pharmacophore hypothesis and shape similarity-based screening algorithm were employed. Of note, the results of the different algorithm were then integrated to eliminate the false positive prediction. Moreover, the inhibitory activities and PK/PD parameters of the leads were tested by Glide and Qikprop algorithm. This resulted in a set of four hits namely; DB12686, DB08341, DB07936, and DB07163. Finally, molecular dynamics simulation was performed using the GROMACS package, to validate the binding kinetics of the hit compound. The compound activity in vitro was assessed by PASS algorithm, highlights the anti-cancer activities of the hits. The structural insights reveal existence of functional moieties such as piperidine carboxamide, benzenesulfonamide, benzamide, and isoindolone in the resultant hits which plays a major role in the anti-cancer activity. Overall, we strongly believe that these ULK1 antagonists could be novel and potent drug candidates for future cancer therapeutics.     

Leuprolide acetate can reversibly prevent egg laying in cockatiels (Nymphicus hollandicus)

Leuprolide acetate acts as a superactive gonadotropin-releasing hormone (GnRH) agonist in mammals. Its administration to humans in a depot formulation (Lupron Depot 3.75 mg; TAP Pharmaceuticals, Deerfield, IL) consisting of microspheres suspended in a diluent of carboxymethylcellulose and other elements leads to an initial increase in serum gonadotropin levels followed by a prolonged suppression of ～ 1 month's duration. To test whether it might act in cockatiels to prevent egg laying, we administered Lupron Depot to groups of pairs (at least 6 pairs/group) stimulated to reproduce by provision of nest boxes and exposure to sexually stimulatory daylengths (15:9 L:D). A single intramuscular injection of Lupron Depot, calculated to achieve a daily release rate of 0 (control; diluent only), 17, 52, or 156 μg/kg/day of leuprolide acetate, was administered on day 0, when birds received nest boxes and after daylength had been stepwise increased. Egg production began on day 12 in the 0 and 17 μg dose groups, and on day 31 in the groups receiving the higher doses. Number of eggs per clutch, candled fertility, and percent hatchability were not significantly different among the groups. In a separate experiment in which leuprolide was administered prior to photostimulation and nest box presentation, nest-inspection behavior was not prevented. We conclude that a single injection of Lupron Depot is effective in reversibly preventing egg laying in cockatiels. © 1994 Wiley-Liss, Inc.     

太白山锐齿栎树干基部两种蚂蚁的筑巢生态学及其蚁巢、体表真菌组成研究

本文研究了太白山锐齿栎景观林带树干基部筑巢的两种蚂蚁的筑巢生态学及其巢内真菌的组成.研究结果表明:亮腹黑褐蚁Formica gagatoides Ruzsky是锐齿栎林中的优势蚁种,可在地表及树干上活动,主要取食栎树枝条上蚜虫所分泌的蜜露及其他昆虫和植物材料;盘腹蚁Aphaenogaster sp.仅在蚁巢周围活动,捕...     

基于多尺度协同的长沙市生态网络构建与层级优化

城市化背景下人类与自然环境的矛盾呈现出多尺度、层级化特征,而传统生态网络的构建方式较少考虑不同尺度下生态要素的关系,无法从区域落实到中心城区,难以形成系统性的解决方案。研究在综合梳理各尺度生态网络构建方法的基础上,以长沙市为例,基于形态学空间格局分析（Morphological Spatial Pattern Analysis,MSPA）、景观连通性原理和生态斑块重要性评价识别生态源地,并通过多层级生态阻力面的确定,综合运用最小费用路径（Least-cost path method,LCP）、电路理论、层级传导理论、尺度嵌套等方法对市域、都市区、中心城区的生态网络进行了协同构建和层级优化,最后基于不同尺度生态网络的特点应用并落实到多层级的国土空间规划体系中。研究结果表明：（1）长沙市域生态网络和都市区生态网络具有较好的层级嵌套特征;共识别两尺度生态叠合源地14个、生态叠合廊道15条,主要通过中心城区内的湘江、浏阳河和捞刀河部分河段与外围生态绿圈相衔接,形成"外环内楔"的空间格局。（2）确定市域重要廊道、市域潜在廊道、生态叠合廊道、都市区重要廊道、都市区潜在廊道的核心保护面积共501.14 km²,并提取位于生态廊道核心保护区范围内的生态夹点和生态障碍点,以进一步落实生态保护修复策略。（3）得到具有重要生态连通功能的中心城区生态绿道长度441.2 km,生态修复单元56个,并结合生态阻力值划分为5级进行针对性修复。（4）基于不同尺度生态网络的衔接、嵌套,最终构建"市域总体生态安全格局-都市区城市生态空间发展格局-以城市绿道为基础的中心城区生态修复单元",并与不同层级的国土空间规划体系相对应。研究结果将为以大城市为中心的跨尺度生态系统修复和生态安全格局构建提供科学参考。     

The Salton Sea as critical habitat to migratory and resident waterbirds

Concern about the Salton Sea ecosystem, based on potential impacts of increasing salinity, contaminants, disease outbreaks, and large die-offs of birds, is heightened because of tremendous prior loss and degradation of wetland habitat in western North America. In 1999, we used a variety of survey methods to describe patterns of abundance of birds at the Salton Sea and in adjacent habitats. Our results further documented the great importance of the Salton Sea within the Pacific Flyway to wintering, migratory, and breeding waterbirds. Exclusive of Eared Grebes, we estimated about 187000 individual waterbirds at the Salton Sea in January, 88000 in April, 170000 in August, and 261000 in November. Additional surveys of Eared Grebes in November and December suggested the total population of all waterbirds was about 434000 to 583000 in those months, respectively. We also documented breeding by about 14000 pairs of colonial waterbirds. Waterbirds were particularly concentrated along the northern, southwestern, southern, and southeastern shorelines and river deltas. By contrast, some species of wading birds (Cattle Egret, White-faced Ibis, Sandhill Crane) and shorebirds (Mountain Plover, Whimbrel, Long-billed Curlew) were much more numerous in agricultural fields of the Imperial Valley than in wetland habitats at the Sea. Various studies indicate the Salton Sea is of regional or national importance to pelicans and cormorants, wading birds, waterfowl, shorebirds, and gulls and terns. Important taxa are the Eared Grebe, American White Pelican, Double-crested Cormorant, Cattle Egret, White-faced Ibis, Ruddy Duck, Yuma Clapper Rail, Snowy Plover, Mountain Plover, Gull-billed, Caspian, and Black terns, and Black Skimmer. Proposed restoration projects should be carefully assessed to ensure they do not have unintended impacts and are not placed where large numbers of breeding, roosting, or foraging birds concentrate. Similarly, plans to enhance opportunities for recreation or commerce at the Sea should aim to avoid or minimize disturbance to birds. Future research should focus on filling gaps in knowledge needed to effectively conserve birds at the Salton Sea.     

Structure of the cytochrome <Emphasis Type="Italic">b</Emphasis><Subscript>6</Subscript><Emphasis Type="Italic">f</Emphasis> complex: new prosthetic groups,Q-space,and the ‘hors d’oeuvres hypothesis’ for assembly of the complex

3-Å crystal structures of the cytochrome b₆f complex have provided a structural framework for the photosynthetic electron transport chain. The structures of the 220,000 molecular weight dimeric cytochrome b₆f complex from the thermophilic cyanobacterium, Mastigocladis laminosus (Kurisu et al. 2003, Science 302: 1009–1014), and the green alga, Chlamydomonas reinhardtii (Stroebel et al. 2003, Nature 426: 413–418), are very similar. The latter is the first structure of a integral membrane photosynthetic electron transport complex from a eukaryotic source. The M. laminosus and C. reinhardtii structures have provided structural information and experimental insights to the properties and functions of three native and novel prosthetic groups, a chlorophyll a, a -carotene, and a unique heme x, one copy of which is found in each monomer of the cytochrome b₆f complex, but not the cytochrome bc₁ complex from the mitochondrial respiratory chain of animals and yeast. Several functional insights have emerged from the structures including the function of the dimer; the properties of heme x; the function of the inter-monomer quinone-exchange cavity; a quinone diffusion pathway through relatively narrow crevices or portals; a modified reaction scheme for n-side quinone redox reactions; a necessarily novel mechanism for quenching of the bound chlorophyll triplet state; a possible role for the bound chlorophyll a in activation of the LHC kinase; and a structural and assembly role for the four small PetG, L, M, and N subunits. An hors doeuvres hypothesis for assembly of the complex is proposed for the small hydrophobic stick or picket fence polypeptides at the periphery of the complex, based on the cis-positive orientation of the small hydrophobic subunits and the toothpick binding mode of the -carotene.     

Inverse Optical Cavity Design for Ultrabroadband Light Absorption Beyond the Conventional Limit in Low‐Bandgap Nonfullerene Acceptor–Based Solar Cells

In the subwavelength regime, several nanophotonic configurations have been proposed to overcome the conventional light trapping or light absorption enhancement limit in solar cells also known as the Yablonovitch limit. It has been recently suggested that establishing such limit should rely on computational inverse electromagnetic design instead of the traditional approach combining intuition and a priori known physical effect. In the present work, by applying an inverse full wave vector electromagnetic computational approach, a 1D nanostructured optical cavity with a new resonance configuration is designed that provides an ultrabroadband (≈450 nm) light absorption enhancement when applied to a 107 nm thick active layer organic solar cell based on a low‐bandgap (1.32 eV) nonfullerene acceptor. It is demonstrated computationally and experimentally that the absorption enhancement provided by such a cavity surpasses the conventional limit resulting from an ergodic optical geometry by a 7% average over a 450 nm band and by more than 20% in the NIR. In such a cavity configuration the solar cells exhibit a maximum power conversion efficiency above 14%, corresponding to the highest ever measured for devices based on the specific nonfullerene acceptor used.     

Halogenated Benzenes Bound within a Non-polar Cavity in T4 Lysozyme Provide Examples of I?S and I?Se Halogen-bonding

We showed earlier that the mutation of Leu99 to alanine in bacteriophage T4 lysozyme creates an internal cavity of volume ∼ 150 Å³ that binds benzene and a variety of other ligands. As such, this cavity provides an excellent target to study protein-ligand interaction. Here, we use low-temperature crystallography and related techniques to analyze the binding of halogen-incorporated benzenes typified by C₆F₅X, where X = H, F, Cl, Br or I, and C₆H₅X, where X = H or I was also studied. Because of the increased electron density of fluorine relative to hydrogen, the geometry of binding of the fluoro compounds can often be determined more precisely than their hydrogen-containing analogs. All of the ligands bind in essentially the same plane but the center of the phenyl ring can translate by up to 1.2 Å. In no case does the ligand rotate freely within the cavity. The walls of the cavity consist predominantly of hydrocarbon atoms, and in several cases it appears that van der Waals interactions define the geometry of binding. In comparing the smallest with the largest ligand, the cavity volume increases from 181 Å³ to 245 Å³. This shows that the protein is flexible and adapts to the size and shape of the ligand. There is a remarkably close contact of 3.0 Å between the iodine atom on C₆F₅I and the sulfur or selenium atom of Met or SeMet102. This interaction is 1.0 Å less than the sum of the van der Waals radii and is a clear example of a so-called halogen bond. Notwithstanding this close approach, the increase in binding energy for the halogen bond relative to a van der Waals contact is estimated to be only about 0.5-0.7 kcal/mol.     

The relationship between introduced European Starlings and the reproductive activities of Mountain Bluebirds and Tree Swallows in British Columbia,Canada

The European Starling Sturnus vulgaris is an introduced species in North America and is an aggressive competitor for tree cavity nest‐sites. Starlings are commonly considered to influence nest‐site selection and reproductive success of native cavity‐nesting species negatively. We examined the relationship between Starling nest density and the fecundity of two native secondary cavity‐using passerines, Mountain Bluebird Sialia currucoides and Tree Swallow Tachycineta bicolor. We monitored a total of 622 nests (approximately equal numbers for each of the three species) in woodpecker‐excavated and naturally occurring cavities in 29 small forest groves in central British Columbia, Canada, between 2000 and 2009. The dimensions of cavities used and the timing of nest initiation overlapped for all species, although Starlings initiated clutches earliest. Mixed‐effects models were used to assess whether nest abundance, clutch size or nest success were affected directly by Starling nest abundance, or indirectly via a shift in cavity selection or timing of breeding. Starlings and Mountain Bluebirds showed inverse trends in nest abundance. Mountain Bluebird clutch sizes were smaller if they were initiated later in the breeding season. There was weak evidence that Tree Swallow clutch size decreased with cavity depth when Starling nests were abundant, and increased with cavity depth where there were few Starling nests. We conclude that despite the aggressive nature of this exotic cavity‐nester, the influence of Starlings on native secondary cavity‐nesting passerines is modest where cavities are abundant.