bluuebunny/crossref_metadata_2025_split huggingface dataset:
Sesquiterpenoids and Phenylpropane Derivatives from Sonchus uliginosus
Authors: Zhang Zhan‐Xin , Xie Wei‐Dong , Li Ping‐Lin , Shi Yan‐Ping , Jia Zhong‐Jian 
Published: December 2006

AbstractSix new compounds were isolated from the whole plant of Sonchus uliginosus, including three eudesmane‐type sesquiterpenoids (1β,6α)‐1,6,14‐trihydroxyeudesm‐3‐en‐12‐oic acid γ‐lactone (1), (1β,6α)‐1,6,14‐trihydroxyeudesma‐3,11(13)‐dien‐12‐oic acid γ‐lactone (2), and (1β,6α)‐1,6‐dihydroxy‐14‐O‐[(4‐hydroxyphenyl)acetyl]eudesma‐3,11(13)‐dien‐12‐oic acid γ‐lactone (3), and three phenylpropane derivatives, 4‐hydroxy‐γ,3,5‐trimethoxybenzenepropanol (6), γ,3,4,5‐tetramethoxybenzenepropanol (7), and γ,3,4,5‐tetramethoxybenzenepropanol acetate (8), together with the two known compounds 4 and 5. The new structures were elucidated by means of spectroscopic methods, such as IR, EI‐MS, HR‐ESI‐MS, 1D‐ and 2D‐NMR, and by comparison of the spectroscopic data with those reported for structurally related compounds.
Synthesis and Photophysical Properties of a Deazaflavin‐Bridged Porphyrinatoiron(III) That Mimics the Interaction of a Deazaflavin Inhibitor with the Heme‐Thiolate Cofactor of Cytochrome P450 3A4
Authors: Müller Michael A. , Gaplovsky Martin , Wirz Jakob , Woggon Wolf‐D. 
Published: December 2006

AbstractCytochrome P450 3A4 metabolizes a majority of administered therapeutic agents in the human liver. We recently reported the synthesis of a new inhibitor,1, whose binding to and displacement from the active site of CYP 3A4 can be conveniently followed by the associated changes in fluorescence intensity. Here we report the synthesis of a bichromophoric compound,6, in which deazaflavin was strapped over the distal side of a porphyrinatoiron(III) complex to mimic the envisaged enzyme–inhibitor interaction within the active site. Femtosecond pump–probe and fluorescence spectroscopies were used to study the photophysical processes of6. Rapid intramolecular energy transfer and enhanced intersystem‐crossing processes induced by the high‐spin FeIIIcentral ion are responsible for the complete suppression of deazaflavin fluorescence in6. Fluorescence quenching is less efficient in the iron‐free analogue of6,i.e., in21.
Internal Nucleophilic Termination in Acid‐Mediated Polyene Cyclizations. Part 5
Authors: Snowden Roger L. , Linder Simon 
Published: December 2006

AbstractTreatment of the acyclic tetraenols (E)‐ and (Z)‐2 with an excess of ClSO3H in 2‐nitropropane at − 80° stereoselectively afforded in 30 and 43% yield, respectively, diastereoisomer mixtures of the racemic, tricyclic ethers 1c,d and 1a,b, together with 20 (Table). Under identical conditions, but with the acyclic pentaenol 10 (1 : 1 diastereoisomer mixture) as substrate, the tricyclic ethers 22a/22b (10 : 1) were isolated in 27% yield. These kinetically controlled stereospecific transformations are thought to proceed via non‐concerted pathways (see Schemes 5 and 7), fully consistent with our earlier work. In contrast, another set of reaction conditions (CF3CO2H, CH2Cl2, − 15° to − 10°) was used for the cyclization of the monocyclic dienols (E)‐3 and (Z)‐3, which resulted in the non‐stereoselective formation of the major products 1c,d and 1a,b, respectively, in 35–37% yield. Representing novel didehydro analogues of the known ambergris odorant (±)‐Ambrox® and its diastereoisomers, the qualitative organoleptic properties of 1a–d and of the 10 : 1 diastereoisomer mixture of the novel tetradehydro analogues 22a/22b are briefly described.
Investigation of the Interactions of β‐Peptides with DNA Duplexes by Circular Dichroism Spectroscopy
Authors: Namoto Kenji , Gardiner James , Kimmerlin Thierry , Seebach Dieter 
Published: December 2006

AbstractThe interaction of β‐peptides with the DNA duplexes of dA20dT20 and a GCN4‐binding CRE sequence was examined. To gauge the factors that govern these interactions, two β‐pentadecapeptides, 1 and 2, a β‐dodecapeptide, 3, three β‐decapeptides, 4–6, three β‐heptapeptides, 7–9, and β‐octaarginine 10 were designed and synthesized. The β‐peptides were conceived to adopt a β‐peptide 314 helix, in which the side chains at position i and i + 3 are aligned vertically along one side of the helix. The side chains of Lys, Asn, and Arg were positioned such that potential H‐bonding sites were created for a helical conformation to interact with the base pairs of DNA. CD Analysis showed that β‐peptides 1, 2, and 10 interacted with dA20dT20. In addition, β‐peptides 1 and 2 showed significant interaction with a DNA‐duplex 20mer containing the ATF/CREB recognition sequence for the regulatory protein GCN4. It is impossible, at this stage of the investigation, to make a safe proposal about the actual nature of the interaction of the structures(s) of the complexes, the formation of which is suggested by the CD spectra reported herein.
Inhibin may be involved in negative feedback in the prairie dog (Cynomys ludovicianus)
Authors: Foreman Darhl 
Published: December 2006

AbstractThe changes in inhibin immunostaining in the gonads during the annual reproductive cycle of both sexes of the prairie dog are described. No inhibin immunostaining was found in primary or secondary follicles of the ovary. Theca and granulosa cells of preovulatory Graafian follicles found in January and February stained for inhibin. Corpora lutea of both pregnant and non‐pregnant females stain more densely for inhibin than follicles. Inhibin staining is present in luteal cells for at least 4 months during regression, longer than detectable progesterone is secreted.Sertoli cells in the testes do not have inhibin immunostaining during recrudescence. These cells show light immunostain for inhibin during peak spermatogenic activity in January and February but stain more deeply during early regression of the testis. Stain is gradually lost in the next 4–5 months as the tubules close. Leydig cells and germ cells do not stain for inhibin at any stage of the annual cycle but interstitial cells and tunic cells stain during the breeding phase.The presence of immunochemical staining for inhibin in prairie dog gonads during regression suggests that inhibin is part of a negative feedback complex that includes progesterone in the female and testosterone or another androgen in the male. Negative feedback during regression may also cause gonadal inactivity. J. Exp. Zool. 307A:67–74, 2007. © 2006 Wiley‐Liss, Inc.
Bleomycin‐induced DNA damage and repair in Xenopus laevis and Xenopus tropicalis
Authors: Banner Sarah H. , Ruben Laurens N. , Johnson Rachel O. 
Published: December 2006

AbstractMicrogel cell electrophoresis has been used with various species to measure breakage of DNA and DNA repair following exposure to the radiomimetic antibiotic, bleomycin. With humans, a high degree of DNA damage is considered to be predictive of cancer susceptibility. Non‐isogeneic Xenopus laevis, the South African clawed toad, rarely develop spontaneous or induced cancers. Here, we investigate bleomycin‐induced DNA damage and repair in splenic lymphocytes of this species to test consistency with cancer predictability. As X. laevis is pseudotetraploid in nature, while Xenopus tropicalis is diploid, we additionally explore the effect of polyploidy on DNA damage and repair in these vertebrates.The results show that higher doses of bleomycin are required to induce comparable levels of DNA damage in both Xenopus species, than in humans. X. tropicalis, the diploid, is more bleomycin‐sensitive than is X. laevis. Additionally, repair rates of damaged DNA of X. laevis lymphocytes are more rapid than those of X. tropicalis, although both are hours slower than human leukocytes. While no data exist on cancer susceptibility in X. tropicalis, the results suggest greater susceptibility to cancer than X. laevis, but less than in humans. Thus, polyploidy serves as a protection against DNA damage and allows more rapid repair. J. Exp. Zool. 307A:84–90, 2007. © 2006 Wiley‐Liss, Inc.
Development management as reflective practice
Authors: Abbott Dina , Brown Suzanne , Wilson Gordon 
Published: December 2006

AbstractThis paper examines development management through the reflections of development managers themselves. They are seen to grapple with the global and local contexts that frame their actions; with operationalising their individual values and ethics about development; and with issues concerning inter‐personal and inter‐organisational relationships. The paper argues that such reflections potentially form the basis of transformations in learning and development practice. However, for this to happen development managers have to embed their reflections within their work, and conceptualise their relations with other stakeholders beyond operational management challenges towards joint learning opportunities. Copyright © 2006 John Wiley & Sons, Ltd.
Kronig–Penney model simulation with equivalent circuit method
Authors: Li Szu‐Ju , Ho Chi‐Hon , Tsai Yao‐Tsung 
Published: December 2006

AbstractThe Kronig–Penney model is quite useful for illustrating many important features of the quantum behaviour of electrons in periodic lattice. Although the Kronig–Penney model is well‐known and has been discussed in solid state textbooks, we try to use a simple and accessible way without the extremely laborious and tedious algebra evaluation to solve Kronig–Penney model. This paper presents a simple method without solving the difficult eigen‐problem to solve the Kronig–Penney model, and the important energy band characteristics can be easily obtained with circuit concepts. The simulation results are presented to demonstrate the accuracy and superiority of the model. Copyright © 2006 John Wiley & Sons, Ltd.
Chronic rotenone treatment induces behavioral effects but no pathological signs of parkinsonism in mice
Authors: Richter Franziska , Hamann Melanie , Richter Angelika 
Published: December 2006

AbstractIt has been hypothesized that exposures to neurotoxic pesticides together with aging and genetic factors increase the risk for developing Parkinson's disease (PD) which is characterized by a progressive degeneration of the nigrostriatal dopaminergic pathway. Chronic treatment with the pesticide rotenone has been reported to induce parkinsonism in rats. Although transgenic mice (but not transgenic rats) are available to investigate the importance of environmental factors in genetically predisposed animals, the effects of chronic rotenone exposure have so far not been examined in intact mice. Therefore, we investigated the effects of chronic exposure to rotenone (2.5 or 4.0–5.0 mg/kg s.c. for 30–45 days) in mice aged 2.5, 5, or 12 months. During the treatment period, the effects on vitality and motor behavior were investigated. Furthermore, the toxicity of rotenone on dopaminergic nigrostriatal neurons and peripheral tissues was examined. In comparison with control mice, rotenone‐treated mice had a decreased spontaneous motor activity, but the density of nigral dopaminergic neurons failed to show any significant changes, except for a tendency to decrease in old mice treated with 4 mg/kg. At the tested doses, rotenone caused a moderate hepatic fatty degeneration. The data indicate that rotenone is not able to cause the neuropathological characteristics of PD in mice under these testing paradigms, which were similar to those of the rotenone rat model. Further studies will have to clarify whether genetic mouse models of PD might be more sensitive to the neurotoxic effects of rotenone. © 2006 Wiley‐Liss, Inc.
Intra‐urban differences in canopy layer air temperature at a mid‐latitude city
Authors: Erell E. , Williamson T. 
Published: December 2006

AbstractDetailed meteorological measurements were carried out in two urban street canyons in central Adelaide and at two reference sites in a suburban location and at an exposed site near the middle of the city for an extended period of nearly a year. The meteorological records revealed substantial differences between air temperature in the urban street canyons and both reference sites. The nocturnal urban heat island observed in most cities was noted in Adelaide street canyons, too. However, the frequent occurrence of a daytime cool island during summer, albeit much weaker than the night‐time phenomenon, is less expected. Both phenomena are attributed at least in part to the increase in surface area participating in energy exchanges with the atmosphere in an urban street canyon compared to a typical rural site, and hence in an increase in the effective thermal mass. The presence of additional thermal mass is manifested not only in the dampening of the diurnal temperature range in the city, but also in a noticeable time lag in the maximum intensity of the daytime cool island. The measurements also demonstrate an observable difference in the daily progression of air temperature between a north–south street canyon and an adjacent east–west oriented street. Copyright © 2006 Royal Meteorological Society
Simultaneous determination of seven phthalates and four parabens in cosmetic products using HPLC‐DAD and GC‐MS methods
Authors: Shen Hao‐Yu , Jiang Hai‐Liang , Mao Hong‐Lei , Pan Gang , Zhou Lu , Cao Yun‐Feng 
Published: December 2006

AbstractStudies on the determination of seven kinds of phthalates, i. e. diethyl phthalate, dipropyl phthalate, dibutyl phthalate, benzyl butyl phthalate, dicyclohexyl phthalate, di‐(2‐ethylhexyl) phthalate, and dioctyl phthalate, and four parabens, i. e. methylparaben, ethylparaben, propylparaben, and butylparaben, in 15 kinds of cosmetic products, including hair sprays, perfumes, deodorants, cream, lotion, etc., by HPLC with diode array detection and GC‐MS in electron impact ionization mode with selected‐ion monitoring have been carried out. Methods have been developed for both qualitative and quantitative detection of phthalates and parabens. Extraction, clean‐up, and analysis procedures have been optimized. HPLC and GC‐MS determinations were performed after sonication‐assisted extraction with methanol and clean‐up with C18 SPE. These techniques permit detection of phthalates at a level of 10.0–100.0 μg/kg and of parabens at a level of 20.0–200.0 μg/kg. Overall recoveries were 85–108% with RSD values of 4.2–8.8%. Only one of the 15 examined samples was free from phthalates and parabens. The remaining 14 samples were found to contain at least three or more of these phthalates and/or parabens. The predominant phthalates and parabens detected in the studied samples were methylparaben, propylparaben, diethyl phthalate, dibutyl phthalate, dicyclohexyl phthalate, and di‐(2‐ethylhexyl) phthalate. The residue level is at 1.22–5289 mg/kg.
Computational proteomics of biomolecular interactions in the sequence and structure space of the tyrosine kinome: Deciphering the molecular basis of the kinase inhibitors selectivity
Authors: Verkhivker Gennady M. 
Published: December 2006

AbstractUnderstanding and predicting the molecular basis of protein kinases specificity against existing therapeutic agents remains highly challenging and deciphering this complexity presents an important problem in discovery and development of effective cancer drugs. We explore a recently introduced computational approach for in silico profiling of the tyrosine kinases binding specificity with a class of the pyrido‐[2,3‐d]pyrimidine kinase inhibitors. Computational proteomics analysis of the ligand–protein interactions using parallel simulated tempering with an ensemble of the tyrosine kinases crystal structures reveals an important molecular determinant of the kinase specificity. The pyrido‐[2,3‐d]pyrimidine inhibitors are capable of dynamically interacting with both active and inactive forms of the tyrosine kinases, accommodating structurally different kinase conformations with a similar binding affinity. Conformational tolerance of the protein tyrosine kinases binding with the pyrido[2,3‐d]pyrimidine inhibitors provides the molecular basis for the broad spectrum of potent activities and agrees with the experimental inhibition profiles. The analysis of the pyrido[2,3‐d]pyrimidine sensitivities against a number of clinically relevant ABL kinase mutants suggests an important role of conformational adaptability of multitargeted kinase inhibitors in developing drug resistance mechanisms. The presented computational approach may be useful in complementing proteomics technologies to characterize activity signatures of small molecules against a large number of potential kinase targets. Proteins 2007. © 2006 Wiley‐Liss, Inc.
Validation and application of a screening method for β2‐agonists, anti‐estrogenic substances and mesocarb in human urine using liquid chromatography/tandem mass spectrometry
Authors: Kang Min‐Jung , Hwang Yong Hee , Lee Won , Kim Dong‐Hyun 
Published: December 2006

AbstractElectrospray ionization (ESI) mass spectra of 15 anti‐estrogenic substances, β2‐agonists and mesocarb were investigated in terms of fragmentation patterns. On the basis of this product ion information, a simultaneous screening method for anti‐estrogenic substances, β2‐agonists and mesocarb was developed for doping control purposes. After hydrolysis, liquid‐liquid extraction was adopted for the sample preparation. The recoveries for all compounds were 30 and 96%. A single liquid chromatography/tandem mass spectrometry (LC/MS/MS) analysis could be performed in 13 min for the analysis of 15 anti‐estrogenic substances, β2‐agonists and mesocarb. A quantitative analysis was also validated. Inaccuracies were below ±12% and precisions varied from 0 to 15.8%. The limit of detection was below 10 ng/mL except formestane (300 ng/mL) and aminoglutethimide (100 ng/mL). The validated method was applied for the analysis of excretion samples. Copyright © 2006 John Wiley & Sons, Ltd.
A cutting process for random mappings
Authors: Hansen Jennie C. , Jaworski Jerzy 
Published: December 2006

AbstractIn this paper we consider a cutting process for random mappings. Specifically, for 0 <m<n, we consider the initial (uniform) random mapping digraphGnonnlabeled vertices, and we delete (if possible), uniformly and at random,mnoncyclic directed edges fromGn. The maximal random digraph consisting of the unicyclic components obtained after cutting themedges is called the trimmed random mapping and is denoted byG. If the number of noncyclic directed edges is less thanm, thenGconsists of the cycles, including loops, of the initial mappingGn. We consider the component structure of the trimmed mappingG. In particular, using the exact distribution we determine the asymptotic distribution of the size of a typical random connected component ofGasn,m→∞. This asymptotic distribution depends on the relationship betweennandmand we show that there are three distinct cases: (i)$m=o(\sqrt{n})$, (ii)$m=\beta\sqrt{n}$, whereβ> 0 is a fixed parameter, and (iii)$\sqrt{n}=o(m)$. This allows us to study the joint distribution of the order statistics of the normalized component sizes ofG. When$m=o(\sqrt{n})$, we obtain thePoisson–Dirichlet(1/2) distribution in the limit, whereas when$\sqrt{n}=o(m)$the limiting distribution is Poisson–Dirichlet(1). Convergence to the Poisson–Dirichlet(θ) distribution breaks down when$m=O(\sqrt{n})$, and in particular, there is no smooth transition from the${\cal P}$D(1/2) distribution to the${\cal P}$D(1) via the Poisson–Dirichlet distribution as the number of edges cut increases relative ton, the number of vertices inGn. © 2006 Wiley Periodicals, Inc. Random Struct. Alg., 30, 287–306, 2007
New integral representations of the polylogarithm function
Authors: Cvijović Djurdje 
Published: December 2006

Maximon has recently given an excellent summary of the properties of the Euler dilogarithm function and the frequently used generalizations of the dilogarithm, the most important among them being the polylogarithm function Li

s

(
z
). The polylogarithm function appears in several fields of mathematics and in many physical problems. We, by making use of elementary arguments, deduce several new integral representations of the polylogarithm Li

s

(
z
) for any complex
z
for which |
z
|<1. Two are valid for all complex
s
, whenever Re
s
>1. The other two involve the Bernoulli polynomials and are valid in the important special case where the parameter
s
is a positive integer. Our earlier established results on the integral representations for the Riemann zeta function
ζ
(2
n
+1),
n
∈
N
, follow directly as corollaries of these representations.
Thermostatic tissue platform for intravital microscopy: ‘the hanging drop’ model
Authors: PAVLOVIC DRAGAN , FRIELING HELGE , LAUER KAI‐STEPHAN , BAC VO HOAI , RICHTER JOERN , WENDT MICHAEL , LEHMANN CHRISTIAN , USICHENKO TARAS , MEISSNER KONRAD , GRUENDLING MATTHIAS 
Published: December 2006

SummaryIntravital microscopy imposes the particular problem of the combined control of the body temperature of the animal and the local temperature of the observed organ or tissues. We constructed and tested, in the rat ileum microcirculation preparation, a new organ‐support platform. The platform consisted of an organ bath filled with physiological solution, and contained a suction tube, a superfusion tube, an intestine‐support hand that was attached to a micromanipulator and a thermometer probe. To cover the intestine we used a cover glass plate with a plastic ring glued on its upper surface. After a routine procedure (anaesthesia, monitoring and surgery), the intestine segment (2–3 cm long) was gently exteriorized and placed on the ‘hand’ of the organ support. A small part of the intestine formed a small ‘island’ in the bath that was filled with physiological salt solution. The cover glass was secured in place. The physiological salt solution from the superfusion tube, which was pointed to the lower surface of the cover glass, formed a ‘hanging drop’. The objective of the microscope was then immersed into distilled water that was formed by the cover glass plastic ring. The ‘hanging drop’ technique prevented any tissue quenching, ensured undisturbed microcirculation, provided for stable temperature and humidity, and permitted a clear visual field.
Nanostructural analysis of starch components by atomic force microscopy
Authors: DANG J. M. C. , BRAET F. , COPELAND L. 
Published: December 2006

SummaryMorphological and structural features of starch from potato (Solanum tuberosa) and rice (Oryza sativa) have been examined using atomic force microscopy. Amylose from potato and rice was observed in aggregated structures, which are suggested to be a result of retrogradation during sample preparation. The degrees of polymerization of amylose from potato and rice starches were calculated from the mean contour lengths of the observed structures to be approximately 1440 and 1860, respectively. Potato amylopectin appeared as a highly branched and extended molecule. Our results show that atomic force microscopy provides a useful method for examining the fine structural features and estimating the dimensions of starch molecules.
Investigation of dyed human hair fibres using apertureless near‐field scanning optical microscopy
Authors: FORMANEK F. , DE WILDE Y. , LUENGO G. S. , QUERLEUX B. 
Published: December 2006

SummaryWe present the first studies of dyed human hair fibres performed with an apertureless scanning near‐field optical microscope. Samples consisted of 5‐µm‐thick cross‐sections, the hair fibres being bleached and then dyed before being cut. Hair dyed with two molecular probes diffusing deep inside the fibre or mainly spreading at its periphery were investigated at a wavelength of 655 nm. An optical resolution of about 50 nm was achieved, well below the diffraction limit; the images exhibited different optical contrasts in the cuticle region, depending on the nature of the dye. Our results suggest that the dye that remains confined at the hair periphery is mainly located at its surface and in the endocuticle.