bluuebunny/crossref_metadata_2025_split huggingface dataset:
Facilitation of tree saplings by nurse plants: Microhabitat amelioration or protection against herbivores?
Authors: Gómez‐Aparicio Lorena , Zamora Regino , Castro Jorge , Hódar Jose A. 
Published: January 2008

AbstractQuestion:Positive interactions are predicted to be common in communities developing under high physical stress or high herbivory pressure due to neighbour amelioration of limiting physical and consumer stresses, respectively. However, when both stress sources meet in the same community, the relative importance of the two facilitation mechanisms is poorly understood. We ask: What is the relative importance of abiotic vs. biotic mechanisms of facilitation of tree saplings by shrubs in Mediterranean mountain forests?Location:Sierra Nevada, SE Spain (1800–1850 m a.s.l.)Methods:Saplings of four tree taxa (Acer opalusssp.grana‐tense, Quercus ilex, Pinus nigra ssp. salzmaniiandP. sylvestrisvar.nevadensis) were planted following a 2 × 2 factorial design: two levels of herbivory (control and ungulate exclusion) and two microhabitats (under shrubs and in open areas). Sapling survival and growth were monitored for five years.Results:Shrubs had positive effects on sapling survival both in control and ungulate excluded plots. This effect was species‐specific, with shrubs increasing the survival ofAcer opalusandQuercus ilexthree and twofold, respectively, but having a minor effect on thePinusspecies. Herbivory damage was also species‐specific, being much higher forAcer opalusthan for any other species. Shrubs did not protect saplings of any species against ungulates. Thus, allAcersaplings (the most damaged species) suffered herbivory outside the exclosures, which largely reduced sapling height.Conclusions:Protection from abiotic stress (summer drought and winter frost) was much more relevant than protection from biotic stress (herbivory). However, we propose that the final balance between the two mechanisms can be expected to vary strongly between sites, depending on the relative magnitude of the different sources of stress and the intrinsic traits (e.g. palatability) of the species interacting.
Should genetic testing for BRCA1/2 be permitted for minors? Opinions of BRCA mutation carriers and their adult offspring
Authors: Bradbury Angela R. , Patrick‐Miller Linda , Pawlowski Kimberly , Ibe Comfort N. , Cummings Shelly A. , Olopade Olufunmilayo I. , Daugherty Christopher K. 
Published: January 2008

AbstractAlthough professional guidelines recommend against testing minors for adult‐onset genetic conditions, the genetic testing of minors for BRCA1/2 alterations has been debated in the literature. To better understand the opinions of BRCA mutation carriers regarding the genetic testing of minors and the cognitive and affective processes underlying these opinions, we interviewed BRCA mutation carriers and their adult offspring who had learned of their parent's BRCA mutation. Semi‐structured interviews were conducted with 53 parents and 22 offspring. In response to a closed‐ended question, 52% (n = 39) of participants were opposed to the testing of minors. Responses to an open‐ended question indicate that many participants (24%, n = 18) feel that testing could be permitted for some minor offspring. Psychological risks and the insufficient maturity of minors were frequent concerns of participants opposed to testing minors. The potential to impact health behaviors was frequently cited as a reason to support the genetic testing of minors. These preliminary results suggest that many BRCA mutation carriers and their adult offspring have concerns about, or are opposed to the genetic testing of minors. However, a significant minority in our study would support testing minors. Greater support for testing among offspring could indicate increasing requests for early genetic diagnosis. Further research is necessary to explore the risks and benefits of providing genetic testing to minors for adult‐onset hereditary cancer syndromes in order to inform clinical practice and public policy and to ensure optimal psychosocial and medical outcomes for all members in families at risk for genetically determined disease. © 2008 Wiley‐Liss, Inc.
Polymeric cinchona alkaloids for the catalytic asymmetric dihydroxylation of olefins
Authors: Cha Rui‐tao , Wang Shao‐yu , Cheng Shao‐ling 
Published: January 2008

AbstractThree cinchona alkaloid copolymers (PMMA‐BQTP, PMA‐BQTP, PAN‐BQTP) have been synthesized by copolymerization. Their structure was characterized by FTIR, GPC, and element analysis. The catalytic activity of these copolymers in asymmetric dihydroxylation (AD) of olefins by OsO4 was studied. The products enantiomeric excesses (ee) and the conversion of the substrate in the dihydroxylation reactions were determined using HPLC. The effect of time, temperature, and recycle times on the reaction was also discussed. The results showed that the copolymers catalyzed the dihydroxylation of the olefins to get diols in high optical yield. However, their catalytic efficiency was largely depended on the nature of olefins. The polymeric cinchona alkaloid can be simply recovered at the end of the reaction by centrifugation and then reused without radical change of activity or enantioselectivity. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008
Microcalorimetric Study on Effect of Chromium(III) and Chromium(VI) Species on the Growth ofEscherichia coli
Authors: YAO Jun , TIAN Lin , WANG Fei , CHEN Hui‐Lun , XU Chao‐Qian , SU Chun‐Li , CAI Ming‐Fa , MASKOW Thomas , ZARAY Gyulad , WANG Yan‐Xin 
Published: January 2008

AbstractThe effects of Cr(III) and Cr(VI) species (Cr2O72−, CrO42−and Cr3+) on the growth ofEscherichia coli(E. coli) have been investigated in detail by microcalorimetry at 37 °C. Parameters including the growth rate constant (k), inhibitory ratio (I), half‐inhibitory concentration (IC50), total heat output (Qtotal), time of the maximum heat production (tlog) in the log phase have been obtained. The results showed that Cr(VI) and Cr(III) had the inhibition effect on the growth ofE. coliin aquatic environment; however, the inhibitory ratio of Cr(III) toE. coliwas smaller than that of Cr(VI). Thekvalues ofE. coliin the presence of Cr(VI) and at high concentrations of Cr(III) were decreased with increasing the concentrations of these chromium species. Among the three chromium species investigated, Cr2O72−was found to be the most poisonous species againstE. coliwith an IC50value of 35.52 µg·mL−1. CrO42−exhibited moderate toxicity onE. coliwith an IC50of 50.24 µg·mL−1, and Cr3+had the lowest toxicity with an IC50of 84.30 µg·mL−1. Microcalorimetry can provide a convenient, sensitive and reliable method to study the effect of various metal species on the growth of bacteria or other microorganisms.
Study on the Retention Behavior of Aromatic Carboxylic and Sulfonic acid on a New Anion Exchange Column
Authors: SHI Ya‐Li , CAI Ya‐Qi , MOU Shi‐Fen 
Published: January 2008

AbstractIon chromatography (IC) has gradually developed into a preferred method for the determination of inorganic anions. And in recent years some low molecular aliphatic acid can be also separated in the ion exchange column with the development of stationary phase. But for the determination of aromatic ionic compounds there are some problems. The aromatic anions show enhanced retention due to interaction with the π electrons of the aromatic backbone. Although the addition of an organic modifier can alleviate the difficulty, it is not the ultimate solution. IonPac AS20 column was developed using a unique polymer bonding technology and its substrate coating is aliphatic backbone. The polymer is completely free of any π electron‐containing substituents in the AS20 column. In this paper, the retention behavior of aromatic carboxylic and sulfonic acid on two hydroxide‐selective columns, IonPac AS11‐HC, AS16, and the new column AS20 was also studied. The result showed that the retentions of ten compounds on three columns were different with each other because of their different column characteristics. Among them 4‐chlorobenzene sulfonic acid, 3,5‐dihydric benzoic acid and salicylic acid obviously exhibited the weakest retention on the IonPac AS20. It was showed that π‐π bond function between anion and stationary phases was weakened in AS20 column because its polymer was completely free of any π electron‐containing substituents. So in this paper the AS20 was selected as an analytical column to separate ten aromatic ionic compounds, fumaric acid with conjugate bond included. The retention behavior, separation of the ten compounds and effect of temperature on their retention in the anion‐exchange column AS20 (2 mm) were studied. The result showed that those compounds could be separated with each other when running in gradient program and the organic modifier was unnecessary during the separation. So it is showed that AS20 column can be used as a separating column because its polymer is completely free of any π electron‐containing substituents. Finally, the effect of temperature on the retention behavior in AS20 column was studied and it was showed that the retention of nine compounds exhibited endothermic behavior.
Synthesis of Lactosylated Piperazinyl Porphyrins and Their Biological Activity
Authors: LI He‐Ping , CAO Zhong , XIAO Hua‐Wu 
Published: January 2008

AbstractThe aim of this work is to synthesize of a new family of lactosylated piperazinly porphyrins, in which the galactoside piperazine moieties are linked to the tetra‐ and mono‐phenyl rings of tetraphenylporphyrin (TPP). 5,10,15,20‐Tetrakis[4‐(4‐lactobionylpiperazin‐1‐yl)phenyl]porphyrin (TLPP) and 5‐mono[4‐(4‐lactobionylpiperazin‐1‐yl)phenyl]‐10,15,20‐triphenylporphyrin (MLPP) have been synthesized. A detailed 1H NMR study gave their complete structural elucidation. The UV‐Visible, mass spectra and elemental analysis are also presented. The biological activity on cancer cells and the pharmacokinetics have also been evaluated, showing a better biological activity, a very high liver to skin ratio and short retention time in tissues. It was suggested that such novel lactosylated piperazinly porphyrins, as potential hepatocyte‐selective targeting drugs, exhibit a promising activity in photodynamic therapy (PDT).
Studies on the Photodynamic Mechanism of Tetrapyrrole Compounds by Laser Flash Photolysis
Authors: DENG Kui , CHEN Zhi‐Long , ZHOU Xing‐Ping , WANG Wen‐Feng , YANG Xiao‐Xia , TIAN Juan 
Published: January 2008

AbstractPhotodynamic therapy (PDT) is a promising new treatment technique which can potentially destroy unwanted and malignant tissues, such as those of cancer. The photodynamic mechanisms of three tetrapyrrole compounds: Mg‐purpurin‐18, tetra(meso‐chlorophenyl)porphyrin (m‐TCPP) and 2,7,12,18‐tetramethyl‐3,8‐di[(1‐isobutoxyl)‐ ethyl]‐13,17‐bis[3‐di(2‐chloroethyl)aminopropyl]porphyrin (TDBP) in acetonitrile were investigated by 355 nm laser flash photolysis. It was found that after laser flash photolysis (LFP), the excited states of TDBP and Mg‐purpurin‐18 could react with O2and1O2was produced, which proved that TDBP and Mg‐purpurin‐18 took effects through type II mechanism in PDT. This suggested that TDBP and Mg‐purpurin‐18 should be suitable for target tissues containing enough O2. Mg‐purpurin‐18 has two extra absorptions at 550 and 700 nm, which means it has broad choices of laser wavelength in PDT. It was also found thatm‐TCPP could be photoionized when excited with 355 nm laser under N2‐saturated condition. It could also react with O2to produce reactive oxygen species such as superoxide and the peroxide anions, but not1O2. These were known as the Type I mechanism. Som‐TCPP could be used even at low oxygen concentration or more polar environments with good behavior in PDT. From the above studies on the three different tetrapyrrole compounds it could be concluded that the structure of porphin ring takes a main role in PDT. And there was important impact on the photodynamic mechanism for the functional group directly connecting with porphin ring, while little influence for the functional group indirectly connecting with porphin ring. These will be of great value in the discovery of new PDT drugs.
Medication overuse headache: clinical features, pathogenesis and management
Authors: Couch James R. , Lenaerts Marc E. 
Published: January 2008

AbstractMedication overuse headache (MOH) is a problem that is estimated to occur in up to 1% of the population. It is a common feature underlying chronic headache, especially chronic migraine. MOH represents a major diagnostic and therapeutic challenge. Many patients are referred to headache specialty clinics, where they can represent the majority of patients. The syndrome remains underdiagnosed and the role of symptomatic medication overuse in producing MOH is often underestimated. With proper education of medical providers, prevention of this too often intractable syndrome could be improved. The basis of therapy is discontinuance of the abused medication. Additional treatment relies on a multifaceted approach that embraces proper use of symptomatic pain medications and management of psychiatric comorbidities and also emphasizes patient education. Various pharmacological regimens, both abortive and prophylactic, are available. Further scientific study is warranted to elucidate the ultimate mechanisms of this syndrome and define more effective treatments. This article gives detailed clinical description, tentative pathophysiological explanation, and therapeutic suggestions. Drug Dev Res 68:449–460, 2007. © 2008 Wiley‐Liss, Inc.
Syk kinase is required for collaborative cytokine production induced through Dectin‐1 and Toll‐like receptors
Authors: Dennehy Kevin M. , Ferwerda Gerben , Faro‐Trindade Inês , Pyż Elwira , Willment Janet A. , Taylor Philip R. , Kerrigan Ann , Tsoni S. Vicky , Gordon Siamon , Meyer‐Wentrup Friederike , Adema Gosse J. , Kullberg Bart‐Jan , Schweighoffer Edina , Tybulewicz Victor , Mora‐Montes Hector M. , Gow Neil A. R. , Williams David L. , Netea Mihai G. , Brown Gordon D. 
Published: January 2008

AbstractRecognition of microbial components by germ‐line encoded pattern recognition receptors (PRR) initiates immune responses to infectious agents. We and others have proposed that pairs or sets of PRR mediate host immunity. One such pair comprises the fungal β‐glucan receptor, Dectin‐1, which collaborates through an undefined mechanism with Toll‐like receptor 2 (TLR2) to induce optimal cytokine responses in macrophages. We show here that Dectin‐1 signaling through the spleen tyrosine kinase (Syk) pathway is required for this collaboration, which can also occur with TLR4, 5, 7 and 9. Deficiency of either Syk or the TLR adaptor MyD88 abolished collaborative responses, which include TNF, MIP‐1α and MIP‐2 production, and which are comparable to the previously described synergy between TLR2 and TLR4. Collaboration of the Syk and TLR/MyD88 pathways results in sustained degradation of the inhibitor of kB (IkB), enhancing NFkB nuclear translocation. These findings establish the first example of Syk‐ and MyD88‐coupled PRR collaboration, further supporting the concept that paired receptors collaborate to control infectious agents.
A novel nano‐micro structured octacalcium phosphate/protein composite coating on titanium by using an electrochemically induced deposition
Authors: Wang Hui , Lin Chang‐Jian , Hu Ren , Zhang Fan , Lin Li‐Wen 
Published: January 2008

AbstractIn this study, a novel nano‐micro structured octacalcium phosphate/protein (OCP/protein) composite coating has been successfully constructed on titanium substrate by using an electrochemically induced deposition technique. The structure and composition of the composite coating were investigated by XRD, XPS, SEM and FTIR. It is shown that the composite coating consists of OCP and protein with a highly ordered and hierarchically porous structure in nano‐micro scale, similar to the naturalbone structure. The nanoindentation experiment proves a good mechanical property for the OCP/protein composite coating on titanium substrate. In the osteoblast cell culture in vitro, the cell adhesion for the OCP/protein composite coating is observed to be greatly improved. © 2008 Wiley Periodicals, Inc. J Biomed Mater Res, 2008
Sealing ability of a novel endodontic cement as a root‐end filling material
Authors: Asgary Saeed , Eghbal Mohammad Jafar , Parirokh Masoud 
Published: January 2008

AbstractThis study investigated the potential usage of novel endodontic cement (NEC) as a root‐end filling material by comparing its sealing ability with that of mineral trioxide aggregate (MTA) and intermediate restorative material (IRM). Sixty‐six single rooted extracted human teeth were cleaned, shaped, and obturated in a similar method. After root‐end resection, 3‐mm deep root‐end cavities were ultrasonically prepared. The samples were divided randomly into 3 test groups, having 20 roots each. Six roots were used as positive and negative controls. Samples were filled with test materials and after one day were immersed in methylene blue dye for 24 h. Roots were sectioned longitudinally and examined under stereomicroscope. Positive and negative controls responded as expected. The increasing order of mean dye microleakage values was NEC < MTA < IRM. ANOVA test showed statistically significant differences among experimental groups (p < 0.001). Tukey's test revealed no significant difference between NEC and MTA. It was concluded that the sealing ability of NEC and MTA is the same and superior to IRM. © 2008 Wiley Periodicals, Inc. J Biomed Mater Res, 2008
Effect of pore size and interpore distance on endothelial cell growth on polymers
Authors: Narayan D. , Venkatraman S. S. 
Published: January 2008

AbstractThe endothelization of polymers using surface modification has received great attention. In particular, creation of physical surface features such as craters or pores has been an active area of research. However, there have been no reported studies of the effects of pore sizes (wide range) and interpore distance on endothelial cell growth. This report details the study done on endothelial cell attachment on the surfaces of polymers modified by porogen leaching. The polymeric system studied includes PLLA and PLGA (80/20). Factors such as porogen type, pore size, and interpore distance were varied, and the surface was evaluated for its influence on endothelial cell growth. Three groups of pore sizes were evaluated: small (5–20 μm), medium (20–45 μm), and large pores (45–90 μm). Two porogens were evaluated: sugar and gelatin. In addition to counting the attached endothelial cells, their proliferation was also quantified. Pore size and interpore distances were evaluated using scanning electron microscopy (SEM), and cell morphology was studied by staining with crystal violet. Analysis of variance demonstrated that the main parameters, pore size and interpore distance were significant in endothelial cell growth. In PLGA (80/20), it was found that endothelial cell growth was enhanced by smaller pore size and lower interpore distance, whereas the growth was poor on PLLA regardless of pore features. © 2008 Wiley Periodicals, Inc. J Biomed Mater Res, 2008
Electromagnetic enhancement of a culture of human SAOS‐2 osteoblasts seeded onto titanium fiber‐mesh scaffolds
Authors: Fassina Lorenzo , Saino Enrica , Visai Livia , Silvani Giulia , Cusella De Angelis Maria Gabriella , Mazzini Giuliano , Benazzo Francesco , Magenes Giovanni 
Published: January 2008

AbstractThe surface properties of a biomaterial are fundamental to determine the response of the host tissue. In the present study, we have followed a particular biomimetic strategy where electromagnetically stimulated SAOS‐2 human osteoblasts proliferated and built a calcified extracellular matrix on a titanium fiber‐mesh surface. In comparison with control conditions, the electromagnetic stimulation (magnetic field intensity, 2 mT; frequency, 75 Hz) caused higher cell proliferation and increased surface coating with type‐I collagen, decorin, and osteopontin (9.8‐fold, 11.3‐fold, and 9.5‐fold, respectively). Reverse transcriptase‐polymerase analysis revealed the electromagnetically upregulated transcription specific for the foregoing matrix proteins and for the growth factor TGF‐β1. The immunofluorescence of type‐I collagen, decorin, and osteopontin showed their colocalization in the cell‐rich areas. The use of an electromagnetic bioreactor aimed at obtaining the surface modification of the biocompatible metallic scaffold in terms of cell colonization and coating with calcified extracellular matrix. The superficially modified biomaterial could be used, in clinical applications, as an implant for bone repair. © 2008 Wiley Periodicals, Inc. J Biomed Mater Res, 2008
Laterally coupled and field‐induced quantum Hall systems
Authors: Habl M. , Wegscheider W. 
Published: January 2008

AbstractA quantum Hall system which is divided into two laterally coupled subsystems by means of a tunneling barrier exhibits a complex Landau level dispersion. Magnetotunneling spectroscopy is employed to investigate the small energy gaps which separate subsequent Landau bands. The control on the Fermi level permits to trace the anticrossings for varying magnetic fields. The band structure calculation predicts a magnetic shift of the band gaps on the scale of the cyclotron energy. This effect is confirmed experimentally by a displacement of the conductance peaks on the axis of the filling factor. Tunneling centers within the barrier are responsible for quantum interferences between opposite edge channels. Due to the disorder potential, the corresponding Aharonov–Bohm interferometers generate additional long‐period and irregular conductance features. In the regime of strong localization, conductance fluctuations occur at small magnetic fields before the onset of the regular Landau oscillations. The Landau dispersion is obtained by a dedicated algorithm which solves the Schrödinger equation exactly for a single electron residing in a quantum Hall system with an arbitrary unidirectional, threefold staircase potential. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Review of (Quantitative) Structure–Activity Relationships for Acute Aquatic Toxicity
Authors: Netzeva Tatiana I. , Pavan Manuela , Worth Andrew P. 
Published: January 2008

AbstractThis paper reviews different approaches described in the literature for estimating the aquatic toxicity of chemical substances. It is based on an extended review performed by the European Chemicals Bureau of the European Commission's Joint Research Centre in support of the development of technical guidance for the implementation of the REACH legislation, and is one of a series of minireviews in this journal. The paper is organised by approach for (Q)SAR development and includes a review of: (i) (Q)SARs for acute aquatic toxicity by chemical class, (ii) (Q)SARs for acute aquatic toxicity by mode of action, (iii) review of statistically derived (Q)SARs, (iv) structural alerts for excess aquatic toxicity and (v) expert systems that combine structural rules and multiple (Q)SAR models to predict aquatic toxicological endpoints. Directions and recommendations for further research are also provided.