bluuebunny/crossref_metadata_2025_split huggingface dataset:
Studies on Interaction between Gatifloxacin and Bovine Serum Albumin by Spectroscopy
Authors: Liu Xiao‐Hui , Ye Yan , Zeng Zheng‐Zhi 
Published: February 2007

AbstractThe interaction of gatifloxacin (HGA) with bovine serum albumin (BSA) at 15 and 37 °C has been investigated by fluorescence quenching spectroscopy in aqueous solution. The bimolecular quenching rate constant was determined by Stern‐Volmer curves and the values were Kq=9.28×1012 L·mol−1·s−1 (15 °C) and Kq=8.51×1012 L·mol−1·s−1 (37 °C). The results showed that the fluorescence quenching mechanism of BSA by HGA was a static quenching procedure. The thermodynamic parameters indicated that electrostatic forces played major role in the interaction of BSA with HGA. Studies on the relationship between the concentration of HGA and the fluorescence intensity of BSA >showed that BSA and HGA bound at the molar ratio 1:1 and the equilibrium constant K0 was 6.80×104 L·mol−1. The binding distances between BSA and HGA and the energy transfer efficiency were obtained based on the FÖrster's theory.
Study of the Electroless Silver Seed Formation on Silicon Surface
Authors: Tong Hao , Wang Chun‐Ming , Ye Wei‐Chun , Chang Yan‐Long , Li Hu‐Lin 
Published: February 2007

AbstractThe silver seed on silicon was prepared through aqueous HF and AgNO3 solution at room temperature. In order to explore the formation process of silver seed on silicon, the methods of open circuit potential with time (OCP‐t), anodic stripping sweep voltammetry (ASV) and scanning tunneling microscope (STM) were used in this work. The procedure of silver nucleus growing into large particles was explained by electro‐negativity. The growth mechanism of silver seed on silicon has been presented: at first, the silver monolayer and multilayer firstly grows onto silicon without fully covering the surface at the expense of silicon etching due to the silver seed attracting the electron from silicon, after that, the monolayer coalesces together, forming continuous grain film with some silver atoms diffusing into the silicon and the multilayer still grows thick simultaneously.
Synthesis and Evaluation of PDE5 Inhibitory Activity of Novel Pyrido[2′,1′:5,1]pyrazolo[4,3‐d]pyrimidin‐4‐one Derivatives
Authors: Tian Guang‐Hui , Xia Guang‐Xin , Jin Wei‐Xi , Chen Xin‐Jian , Lai Shun‐An , Wei Ya‐Bing , Ji Ru‐Yun , Shen Jing‐Shan 
Published: February 2007

AbstractNovel pyridopyrazolopyrimidinone derivatives were designed and synthesized as potential PDE5 inhibitors. The target compounds demonstrated significant inhibitory activity against human platelet PDE5, but less potent than sildenafil.
Structure–Activity Study on the Spatial Arrangement of the Third Aromatic Ring of Endomorphins 1 and 2 Using an Atypical Constrained C Terminus
Authors: Yu Ye , Shao Xuan , Cui Yun , Liu Hong‐mei , Wang Chang‐ling , Fan Ying‐zhe , Liu Jing , Dong Shou‐liang , Cui Yu‐xing , Wang Rui 
Published: February 2007

AbstractThe discovery of endomorphins (EMs) has opened the possibility of searching for new analgesics. However, the design of peptide analgesics has proven to be very difficult as a result of their conformational flexibility and a lack of clarity in structure–activity relationships (SAR). In EMs, the amino acid side chains exhibit considerable conformational flexibility, especially in the third aromatic ring, which is free to adopt a bioactive conformation. To resolve these problems, a series of C terminus EM analogues, [Xaa4‐R]EMs, modified through the substitution of Phe4with nonaromatic residues and termination with benzyl groups, were designed to generate conformational constrains of the third aromatic ring by amide bond and torsion angles (ϕ4andψ4) of Xaa4. Introduction of (S)‐α‐methyl or (S)/(R)‐α‐carboxamide on the methylene unit of the benzyl group was designed to produce an atypical topographical constraint (ϕ5) of the third aromatic ring rotation. Interestingly, some EM derivatives, with elimination of the C‐terminal carboxamide group and significant changes in the address sequence (Phe4‐NH2), still exhibited higher μ‐opioid receptor (MOR) affinity than unmodified EMs. In contrast, some analogues with incorrectly constrained C termini displayed very low affinity and pharmacological activities. Thus, our results indicate that these EM analogues, with atypical constrained C termini, provide model compounds with potent MOR agonism. They also give evidence that the proper spatial orientation and conformational restriction of the third aromatic ring are crucial for the interaction of EMs with MOR.
Toward designing asymmetric head gradient coils for high‐resolution imaging
Authors: Vegh Viktor , Sanchez Hector , Brereton Ian M. , Crozier Stuart 
Published: February 2007

AbstractThe aim of the research described here is to design head gradient coils using approaches previously developed by the authors. The wave equation method for designing gradient coils is used to design a transverse gradient coil winding on a cylindrical/spherical former. The results are compared with asymmetric cylindrical designs and other well‐known head gradient coil designs to establish the quality of the gradient coil winding. Comparisons of field, inductance, torque, and other quality factors are made before conclusions are drawn about the adequacy of such a winding pattern to perform high‐resolution imaging of the head. We show that it is possible to generate a robust winding pattern that has good efficiency and produces a sufficiently large imaging volume. © 2007 Wiley Periodicals, Inc. Concepts Magn Reson Part B (Magn Reson Engineering) 31B: 1–11, 2007
Assessing the impact of pollution on the Japaratuba river in Brazil using the Drosophila wing spot test
Authors: Moraes Pantaleão Silmara de , Alcântara Ayda Vera , Hora Alves José do Patrocínio , Pavanin Luiz Alfredo , Graf Ulrich , de Rezende Alexandre Azenha Alves , Bueno Valadares Bruno Lassmar , José Fragiorge Edson , de Souza Neila Coelho , Rosa Guterres Zaira da , Spanó Mário Antoônio 
Published: February 2007

AbstractThe Drosophila melanogaster somatic mutation and recombination test (SMART) was used to assess the genotoxicity of surface (S) and bottom (B) water and sediment samples collected from Sites 1 and 2 on the Japaratuba River (Sergipe, Brazil), an area impacted by a petrochemical industrial complex that indirectly discharges treated effluent (produced water) into the river. The genotoxicity tests were performed in standard (ST) cross and high bioactivation (HB) cross flies and were conducted on samples taken in March (dry season) and in July (rainy season) of 2003. Mutant spot frequencies found in treatments with unprocessed water and sediment samples from the test sites were compared with the frequencies observed for similar samples taken from a clean reference site (the Jacarecica River in Sergipe, Brazil) and those of negative (ultrapure water) controls. While samples from the Japaratuba River generally produced greater responses than those from the Jacarecica River, positive responses were detected for both the test and reference site samples. All the water samples collected in March 2003 were genotoxic. In July 2003, the positive responses were restricted to water samples collected from Sites 1 B and 2 S in the ST cross. The genotoxicity of the water samples was due to mitotic recombination, and the samples produced similar genotoxic responses in ST and HB flies. The spot frequencies found in the July water samples were considerably lower than those for the March water samples, suggesting a seasonal effect. The only sediment samples that were genotoxic were from Site 1 (March and July) and from the Jacarecica River (March). The genotoxins in these samples produced both somatic mutation (limited to the Site 1 sample in HB flies) and recombination. The results of this study indicate that samples from both the Japaratuba and Jacarecica Rivers were genotoxic, with the most consistently positive responses detected with Site 1 samples, the site closest to the putative pollution source. Environ. Mol. Mutagen. 48:, 2007. © 2007 Wiley‐Liss, Inc.
Cytotoxicity and genotoxicity of ultrafine crystalline SiO2 particulate in cultured human lymphoblastoid cells
Authors: Wang Jing J. , Sanderson Barbara J.S. , Wang He 
Published: February 2007

AbstractRespirable crystalline silica has been classified as a human lung carcinogen. Ultrafine (diameter < 100 nm) silica particles may be important in carcinogenesis, although the mechanisms remain unclear. In the present study, WIL2‐NS cells were incubated for 6, 24, and 48 hr with 0, 30, 60, and 120 μg/ml ultrafine crystalline SiO2 (UF‐SiO2). The cytotoxic and genotoxic effects caused by UF‐SiO2 in cultured human cells were investigated via a set of bioassays. Significant dose‐ dependent decreases in percent cell viability were seen with increasing dose of UF‐SiO2 in the methyl tetrazolium assay. Significant decreases were seen at 120 μg/ml (58, 38, and 57% for 6, 24, and 48‐hr exposure, respectively). During 4 days growth in the flasks, there was a slight recovery observed after washing off UF‐SiO2 as measured by the population growth assay. Significant dose‐dependent reduction in the cytokinesis block proliferation index was observed by the cytokinesis block micronucleus assay. Treatment with 120 μg/ml UF‐SiO2 for 24 hr produced a fourfold increase in the frequency of micronucleated binucleated cells (MNBNC). The increase in MNBNC was dose‐dependent. The lowest dose that gave a statistically significant increase in MNBNC was 30 μg/ml (24‐hr treatment), which had cytotoxicity of less than 10%. There was no significant difference in DNA strand breakage as measured by the Comet assay. A significant increase in induced mutant frequency was found at 120 μg/ml as detected by the hypoxanthine guanine phosphoribosyltransferase mutation assay. The results indicate that UF‐SiO2 is cytotoxic and genotoxic in cultured human cells. Environ. Mol. Mutagen., 2007. © 2007 Wiley‐Liss, Inc.
Respiratory Levels and Adaptations in Four Freshwater Species of Gammarus (Crustacea: Amphipoda)
Authors: Toman Mihael J. , Dall Peter C. 
Published: February 2007

AbstractRespiration of four freshwater species of the amphipod crustacean Gammarus: G. fossarum, G. lacustris (river and lake), G. pulex and G. roeseli were measured in a closed, stirred respirometric chamber with a micro‐electrode. Oxygen consumption, expressed as weight‐specific oxygen uptake (Rs) in relation to decreasing oxygen concentration, varied at air saturation from 0.86 (G. lacustris, lake) to 2.06 μl O2 mg−1 AFDW h−1 (G. pulex). Rs also differed intra‐specifically among the two populations of G. lacustris.G. lacustris (river), G. pulex and G. roeseli expressed moderate ability to regulate their oxygen consumption at decreasing oxygen concentrations, whereas the regulation ability was higher in G. lacustris (lake) and in G. fossarum, which maintain high oxygen uptake at oxygen levels >2 mg O2 l−1.All four Gammarus species are partial regulators in response to variations in oxygen concentration. The differences between species are considered too small to account for their natural distributions. It appears that the tolerances of Gammarus species to organic pollution depend only in part on oxygen conditions.
Hydrodynamic Characteristics of Daphnia middendorffiana
Authors: Vega Marina Patricia , Clausse Alejandro 
Published: February 2007

AbstractSinking terminal velocities of D. middendorffiana (with and without tail spine) were measured and correlated with morphological parameters and water temperature. The main dimensions of the body showed positive growths rate correlations with the body weight. In turn, negative allometric variation was observed in the tail‐spine length. The density of D. middendorffiana was age specific, and decreased as the individual grew. No differences in the sinking terminal velocities and trajectories between individuals with and without tail spine were observed. The observed hydrodynamic characteristics of D. middendorffiana were simulated by means of a model based on equivalent ellipsoids and spheres. The analysis showed that the effects of shape and the body projections are negligible on the sinking rates of D. middendorffiana.
Plankton Seasonal Dynamics and Its Controlling Factors in Shallow Polymictic Eutrophic Lake Võrtsjärv, Estonia
Authors: Nõges Tiina , Kisand Veljo , Nõges Peeter , Põllumäe Arno , Tuvikene Lea , Zingel Priit 
Published: February 2007

AbstractAn analysis of plankton seasonal succession in large shallow eutrophic lake Võrtsjärv (270 km2, mean depth 2.8 m, max. depth 6 m) is presented. Weekly samples for 1995 have been analysed using the PEG model approach. In winter, light was the main factor controlling phytoplankton growth. In early spring phytoplankton was mainly resource‐controlled, competition for phosphorus being the main driving force. Ciliates (Paradileptus sp., Strobilidium sp. and Vorticella sp.) were the first herbivores which started to increase in April causing a twofold decline of phytoplankton biomass. The annual maximum of primary production (PP) in early May was probably caused by soluble reactive phosphorus (SRP), regenerated by herbivores, and stirred up from bottom sediments as a result of strong wind stress. This primary production peak provided substrate for further increase of bacterial biomass. The more abundant food supply supported the development of the second spring peak of herbivores (ciliates, rotifers, juvenile copepods) which was followed by the second modest “clear water phase” in late May. Silicon was depleted by the end of May causing a strong decrease in primary production of the diatom‐dominated community, whereas the biomass of the cyanophytes increased under the improved nutrient conditions. Some weeks later, inorganic N was depleted and the period of N limitation with the appearance of N‐fixing cyanophytes began. The ciliate collapse at the beginning of June coincided with the start of the cladoceran development and with the increase of other metazooplankton groups. This explains the further decrease of the biomass of phytoplankton and bacteria in spite of their high production. Beginning from late June, silicon appeared again and SRP started to occur periodically, while inorganic N remained close to zero until November. During this period, phytoplankton development relied to a great extent on the N‐fixation and N‐regeneration potential. The collapse of the ciliate community in September removed the top‐down control from bacteria and their biomass increased, while the development of cladocerans still suppressed phytoplankton biomass in spite of a quite high PP. In October phytoplankton biomass and chlorophyll a (Chla) increased, SRP was completely depleted by the middle of October reflecting a slow regeneration due to the declined activity of zooplankton in cold water. In November nitrates appeared again, and silicon reached the same level as in spring. The biomass of N‐fixing Aphanizomenon skujae decreased while Limnothrix redekei and L. planctonica were quite abundant together with diatoms.
Distribution of Brachionidae (Rotifera, Monogononta) in Inner Mongolian Waters
Authors: Rong Su , Segers H. , Dumont H. J. 
Published: February 2007

AbstractTwo‐hundred and fourty‐six freshwater and saline‐alkaline waters in Inner Mongolia, P.R. China were surveyed for Brachionidae. Twenty‐nine brachionid morphospecies (33 taxa) are recorded, four are new to China. Some data on their distribution, and comments on selected taxa are provided.Brachionus asplanchnoides(stat.nov.) is reinstated at the morphospecies level. We suggest that this taxon may be used in aquaculture, considering that, by its large size, it extends the size range of brackish‐water Rotifera potentially available as food for fish larvae.
The Influence of Hydraulic Stress on Microdistribution Patterns of Zoobenthos in a Sandstone Brook (Weidlingbach, Lower Austria)
Authors: Möbes‐Hansen B. , Waringer J. A. 
Published: February 2007

AbstractIn the Weidlingbach, a low‐order forest stream in the Wienerwald area near Vienna (Austria), hydraulic stress was measured at 112 locations from which benthic fauna (=33318 specimens of macro‐invertebrates) was collected between March and September 1995. For measuring hydraulic stress a set of FST hemispheres was used. The most abundant taxa studied (= 90.7% of the total) were Gammarus fossarum Koch (Amphipoda), Leuctra spp. (Plecoptera), the ephemeropterans Baetis rhodani (Pictet), B. vernus (Curtis), Habroleptoides confusa Sartori and Jacob, Ecdyonurus starmachi Sowa and the caddisfly Hydropsyche instabilis (Curtis).Five mayfly, four stonefly and six caddisfly taxa significantly (p < 0.05) preferred the lotic subsection of the research area, whereas Ephemera danica Müller significantly (p < 0.001) preferred the lentic subsection.In the species studied in detail, medians of their FST hemisphere ranges varied from 8 (e.g. Brachyptera risi (Morton)) to 2 (e.g. Paraleptophlebia submarginata (Stephens)).A comparison of microdistribution patterns at low and high discharge revealed no significant shift in FST hemisphere numbers and, hence, in exposure to hydraulic stress in Hydropsyche instabilis and Rhyacophila fasciata Hagen; both species were most abundant in high stress areas, independent of discharge. On the other hand, most other species studied in detail exhibited a shift to lower hydraulic stress at high discharge, whereas Electrogena ujhelyii (Sowa) was evenly distributed (p > 0.05) over the whole range of hydraulic stress, independent of discharge.
Succession of Physical and Chemical Conditions and of Crustacean Communities in Some Small, Man Made Water Bodies
Authors: Maier Gerhard , Hössler Jürgen , Tessenow Uwe 
Published: February 2007

AbstractWe studied physical and chemical conditions and the crustacean communities in temporary ponds in a military area in South Germany. All ponds were formed by driving of tanks. They were turbid, without higher aquatic plants but contained a unique crustacean community with endangered species such as the anostracan Branchipus schaefferi, the copepods Cyclops furcifer and Metacyclops minutus and the cladocerans Daphnia obtusa, Moina brachiata and Macrothrix hirsuticornis. Branchipus was only present in ponds which dried out and where driving occurred. Ponds which did not dry out and where driving events were rare or did not take place were devoid of Branchipus. Physical and chemical conditions were similar in ponds with and without Branchipus. Day‐night fluctuations of temperature were up to 15 °C in summer. Conductivity was 200–300 μS cm−1, hardness ranged between 2 and 3.5 meq 1−1, alcalinity between 1 and 3 meq 1−1, pH between 7.5 and 9, dissolved phosphorus was <20 μg 1−1, concentration of nitrogen was <0.1 mg 1−1 and oxygen saturation was >60% in the ponds except one pond where concentrations of nutrients and conductivity were somewhat higher. When driving of tanks had been stopped the number and size of the ponds decreased and their character changed. Branchipus schaefferi and other endangered species disappeared and more but common, benthic species such as the cladoceran Chydorus sphaericus and the copepods Megacyclops viridis and Eucyclops serrulatus gained importance. Branchipus schaefferi is now close to extinction. Conductivity, hardness, alcalinity increased while pH decreased probably because algae were replaced by marsh plants. We conclude that driving of tanks raised clay particles, prevented the growth of higher aquatic vegetation and condensed the bottom sediments. All this was necessary to keep the ponds in an early stage of succession thus providing conditions necessary to maintain Branchipus.
A co‐clustering model involving α5β1 integrin for the biological effects of GPI‐anchored human carcinoembryonic antigen (CEA)
Authors: Camacho‐Leal Pilar , Zhai Alexander B. , Stanners Clifford P. 
Published: February 2007

AbstractCEA functions as an intercellular adhesion molecule and is up‐regulated in a wide variety of human cancers, including colon, breast and lung. Its over‐expression inhibits cellular differentiation, blocks cell polarization, distorts tissue architecture, and inhibits anoikis of many different cell types. Here we report results concerning the molecular mechanism involved in these biological effects, where relatively rapid molecular changes not requiring alterations in gene expression were emphasized. Confocal microscopy experiments showed that antibody‐mediated clustering of a deletion mutant of CEA (ΔNCEA), normally incapable of self binding and clustering, led to the co‐localization of integrin α5β1 with patches of ΔNCEA on the cell surface. Activation of α5, as defined by an anti‐α5 mAb‐sensitive increase in cell adhesion to immobilized fibronectin, and an increased binding of soluble fibronectin to cells, was also observed. This was accompanied by the recruitment of integrin‐linked kinase (ILK), protein kinase B (PKB/Akt), and the mitogen‐activated protein kinase (MAPK) to membrane microdomains and the phosphorylation of Akt and MAPK. Inhibition of PI3‐K and ILK, but not MAPK, prevented the α5β1 integrin activation. Conversely, anti‐α5 antibody inhibited the PI3‐K‐mediated activation of Akt, implying the involvement of outside‐in and inside‐out signaling in integrin activation. Therefore we propose that CEA‐mediated signaling involves clustering of CEA and co‐clustering and activation of the α5β1 and associated specific signaling elements on the internal surfaces of membrane microdomains. These changes may represent a molecular mechanism for the biological effects of CEA. J. Cell. Physiol. 211: 791–802, 2007. © 2007 Wiley‐Liss, Inc.
Growth plate formation and development in alligator and mouse metapodials: evolutionary and functional implications
Authors: Reno Philip L. , Horton Walter E. , Elsey Ruth M. , Lovejoy C. Owen 
Published: February 2007

AbstractMammalian metapodials (metacarpals and metatarsals), unlike most long bones, form a single growth plate, and undergo longitudinal growth at only one end. The growth dynamics of non‐mammalian tetrapod metapodials have not been systematically examined in order to determine if unidirectional growth is unique to mammals. Here we compare murine metapodial ossification in growth stages that parallel those of embryonic, juvenile and subadult American alligators (Alligator mississippiensis). Safranin O staining was used for qualitative histology, and chondrocyte differentiation and proliferation were assessed via immunohistochemistry for type X collagen and proliferative cell nuclear antigen (PCNA). We establish that growth plates form at both ends of alligator metapodials and are maintained in the subadult. PCNA results show that alligators and mice share common patterns of chondrocyte proliferation during growth plate formation. In addition, while alligators and mice differ initially in the degree of organization and pace of chondrocyte differentiation, these parameters are largely similar in established growth plates. However, the replacement of cartilage by bone is highly irregular throughout growth in the alligator, in contrast to the more uniform process in the mouse. These results indicate that while alligators and mammals share common mechanisms of chondrocyte regulation, they differ substantially in their processes of ossification. Phylogenetic analysis indicates that the direct ossification of one epiphysis and reliance on a single growth plate is a derived character (synapomorphy) in therian mammals and likely indicates an adaptation for erect quadrupedal gait. J. Exp. Zool. (Mol. Dev. Evol.) 308B:283–296, 2007. © 2007 Wiley‐Liss, Inc.