bluuebunny/crossref_metadata_2025_split huggingface dataset:
Straightforward Synthesis of Fluorinated Amphiphilic Thiols
Authors: Gentilini Cristina , Boccalon Mariangela , Pasquato Lucia 
Published: May 2008

AbstractC8‐perfluoroalkyl thiols bearing a polyoxyethylene chain of variable length were prepared in good yields following a straightforward synthetic strategy. These thiols are soluble in organic solvents of different polarities from chloroform to methanol. The thiol with a PEG550 chain shows very good solubility in water. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2008)
Synthesis of 1‐Silabicyclo[4.4.0]dec‐5‐en‐4‐ones: A Model of the A and B Rings of 10‐Silatestosterone
Authors: Díez‐González Silvia , Paugam Renée , Blanco Luis 
Published: May 2008

Abstract1‐Silabicyclo[4.4.0]dec‐5‐en‐4‐ones, a novel type of organosilicon compound, have been prepared from 2‐methylidene‐1‐(3‐oxopropyl)‐1‐silacyclohexanes by an ene reaction as the key transformation. Various routes to the starting aldehydes from 3‐halopropyl, allyl, or 3‐(4‐methoxybenzyloxy)propylsilanes have been investigated. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2008)
Intermolecular Hydrogen‐Bonding Pattern of a Glycosyl Donor: The Key to Understanding the Outcome of Sialylation
Authors: Kononov Leonid O. , Malysheva Nelly N. , Kononova Elena G. , Orlova Anna V. 
Published: May 2008

AbstractChanges in the hydrogen‐bonding pattern in solutions of glycosyl donor induced by the addition of external amides/imides or by concentration changes influence the yield and stereoselectivity of sialylation. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2008)
Predicting mating flights through meteorological cues using multi‐scale logistic regression
Authors: Kim MyungSuk , Lim Johan , Wang Suojin 
Published: May 2008

AbstractThe red imported fire ant is one of the most destructive animals in the US. Its prolific ability through mating flights has aggravated the situation. Understanding the environmental cues triggering mating flights would be important for a comprehensive control solution. Fire ant colony activities related to mating flights were daily monitored from April 2001 to March 2002, and the associated weather data were documented. The method of logistic regression is used to identify environmental factors associated with mating flight where multi‐scale decomposition of the meteorological variables is considered to identify the within and the between cues for mating flights. Our empirical results indicate that ambient temperature, relative humidity, wind speed, barometric pressure, and recent rain are significant factors that trigger or influence fire ant mating flights. Among those factors, the ambient temperature, the change in barometric pressure, relative humidity, wind speed, and recent rain are found to be the macro‐scale cues, whereas the ambient temperature is also found to be the micro‐scale cues. Copyright © 2008 John Wiley & Sons, Ltd.
Running increases neurogenesis without retinoic acid receptor activation in the adult mouse dentate gyrus
Authors: Åberg Elin , Perlmann Thomas , Olson Lars , Brené Stefan 
Published: May 2008

AbstractBoth vitamin A deficiency and high doses of retinoids can result in learning and memory impairments, depression as well as decreases in cell proliferation, neurogenesis and cell survival. Physical activity enhances hippocampal neurogenesis and can also exert an antidepressant effect. Here we elucidate a putative link between running, retinoid signaling, and neurogenesis in hippocampus. Adult transgenic reporter mice designed to detect ligand‐activated retinoic acid receptors (RAR) or retinoid X receptors (RXR) were used to localize the distribution of activated RAR or RXR at the single‐cell level in the brain. Two months of voluntary wheel‐running induced an increase in hippocampal neurogenesis as indicated by an almost two‐fold increase in doublecortin‐immunoreactive cells. Running activity was correlated with neurogenesis. Under basal conditions a distinct pattern of RAR‐activated cells was detected in the granule cell layer of the dentate gyrus (DG), thalamus, and cerebral cortex layers 3–4 and to a lesser extent in hippocampal pyramidal cell layers CA1–CA3. Running did not change the number of RAR‐activated cells in the DG. There was no correlation between running and RAR activation or between RAR activation and neurogenesis in the DG of hippocampus. Only a few scattered activated retinoid X receptors were found in the DG under basal conditions and after wheel‐running, but RXR was detected in other areas such as in the hilus region of hippocampus and in layer VI of cortex cerebri. RAR agonists affect mood in humans and reduce neurogenesis, learning and memory in animal models. In our study, long‐term running increased neurogenesis but did not alter RAR ligand activation in the DG in individually housed mice. Thus, our data suggest that the effects of exercise on neurogenesis and other plasticity changes in the hippocampal formation are mediated by mechanisms that do not involve retinoid receptor activation. © 2008 Wiley‐Liss, Inc.
PLC‐β1 knockout mice as a model of disrupted cortical development and plasticity: Behavioral endophenotypes and dysregulation of RGS4 gene expression
Authors: McOmish Caitlin E. , Burrows Emma L. , Howard Monique , Hannan Anthony J. 
Published: May 2008

AbstractThe complexity of the genetics underlying schizophrenia is highlighted by the multitude of molecular pathways that have been reported to be disrupted in the disorder including muscarinic, serotonergic, and glutamatergic signaling systems. It is of interest, therefore, that phospholipase C‐β1 (PLC‐β1) acts as a point of convergence for these pathways during cortical development and plasticity. These signaling pathways, furthermore, are susceptible to modulation by RGS4, one of the more promising candidate genes for schizophrenia. PLC‐β1 knockout mice were behaviorally assessed on tests including fear conditioning, elevated plus maze, and the Y maze. In situ hybridization was used to assess RGS4 expression. We found that PLC‐β1 knockout mice display abnormal anxiety profiles on some, but not all measures assessed, including decreased anxiety on the elevated plus maze. We also show memory impairment and a complete absence of acquisition of hippocampal‐dependent fear conditioning. Furthermore, at a molecular level, we demonstrate dramatic changes in expression of RGS4 mRNA in selective regions of the PLC‐β1 knockout mouse brain, particularly the CA1 region of the hippocampus. These results validate the utility of the PLC‐β1 knockout mouse as a model of schizophrenia, including molecular and cellular evidence for disrupted cortical maturation and associated behavioral endophenotypes. © 2008 Wiley‐Liss, Inc.
Propagation of specific network patterns through the mouse hippocampus
Authors: Both Martin , Bähner Florian , von Bohlen und Halbach Oliver , Draguhn Andreas 
Published: May 2008

AbstractNetwork oscillations bind neurons into transient assemblies with coherent activity, enabling temporal coding. In the mammalian hippocampus, spatial relationships are represented by sequences of action potentials of place cells. Such patterns are established during memory acquisition and are re‐played during sharp wave‐ripple complexes in CA1 in subsequent sleep episodes. These events originate in CA3 and travel towards CA1 and downstream cortical areas. It is unclear, however, whether specific sequences of ripple‐associated firing are solely defined within the CA1 network or whether these patterns are directly entrained by preceding activities of neurons within CA3. Using a model of sharp wave‐ripple oscillations (SPW‐R) in mouse hippocampal slices we analyzed the propagation of these signals between CA3 and CA1. We found tight coupling between high‐frequency network activity in CA3 and CA1. Propagation of ripples through the hippocampal loop maintained precise temporal relationships at the network and cellular level, as indicated by coupling of field potentials, multiunit and single cell activity between major portions of CA3 and CA1. Moreover, SPW‐R‐like activity in CA1 could be elicited by electrical stimulation within area CA3 while antidromic activation of CA1 failed to induce organized high‐frequency oscillations. Our data show that the specificity of neuronal assemblies is maintained with cell‐to‐cell precision while SPW‐R propagate along the hippocampal loop. © 2008 Wiley‐Liss, Inc.
Status epilepticus during old age is not associated with enhanced hippocampal neurogenesis
Authors: Rao Muddanna S. , Hattiangady Bharathi , Shetty Ashok K. 
Published: May 2008

AbstractIncreased production of new neurons in the adult dentate gyrus (DG) by neural stem/progenitor cells (NSCs) following acute seizures or status epilepticus (SE) is a well known phenomenon. However, it is unknown whether NSCs in the aged DG have similar ability to upregulate neurogenesis in response to SE. We examined DG neurogenesis after the induction of continuous stages III‐V seizures (SE) for over 4 h in both young adult (5‐months old) and aged (24‐months old) F344 rats. The seizures were induced through 2–4 graded intraperitoneal injections of the excitotoxin kainic acid (KA). Newly born cells in the DG were labeled via daily intraperitoneal injections of the 5′‐bromodeoxyuridine (BrdU) for 12 days, which commenced shortly after the induction of SE in KA‐treated rats. New cells and neurons in the subgranular zone (SGZ) and the granule cell layer (GCL) were analyzed at 24 h after the last BrdU injection using BrdU and doublecortin (DCX) immunostaining, BrdU‐DCX and BrdU‐NeuN dual immunofluorescence and confocal microscopy, and stereological cell counting. Status epilepticus enhanced the numbers of newly born cells (BrdU+ cells) and neurons (DCX+ neurons) in young adult rats. In contrast, similar seizures in aged rats, though greatly increased the number of newly born cells in the SGZ/GCL, failed to increase neurogenesis due to a greatly declined neuronal fate‐choice decision of newly born cells. Only 9% of newly born cells in the SGZ/GCL differentiated into neurons in aged rats that underwent SE, in comparison to the 76% neuronal differentiation observed in age‐matched control rats. Moreover, the number of newly born cells that migrate abnormally into the dentate hilus (i.e., ectopic granule cells) after SE in the aged hippocampus is 92% less than that observed in the young adult hippocampus after similar SE. Thus, SE fails to increase the addition of new granule cells to the GCL in the aged DG, despite a considerable upregulation in the production of new cells, and SE during old age leads to much fewer ectopic granule cells. These results have clinical relevance because earlier studies have implied that both increased and abnormal neurogenesis occurring after SE in young animals contributes to chronic epilepsy development. © 2008 Wiley‐Liss, Inc.
Multiple signals of recognition memory in the medial temporal lobe
Authors: Yassa Michael A. , Stark Craig E.L. 
Published: May 2008

AbstractThe medial temporal lobe (MTL) is known to play an essential role in recognition memory (the ability to judge the prior occurrence of a stimulus). Electrophysiological studies in nonhuman primates have suggested the presence of more than one type of recognition signal in the medial temporal lobe (e.g., novelty, familiarity, and recency). It has also been suggested that the perirhinal cortex plays an essential role in visual recognition memory. Here, we present fMRI results from 16 college‐aged participants who underwent a continuous yes/no recognition task of novel and familiar pictures with multiple stimulus presentations. Our goal was to understand the dynamics of recognition in the MTL over multiple trials. We hypothesized that we could see changes in signal with repeated exposure that carry information related to novelty, familiarity, and recency. Whole brain activation maps demonstrated a strong novelty effect, marked by activity in several frontal and occipital regions that decreases with increasing number of presentations. The opposite pattern was observed in several other regions that include the supramarginal gyrus and inferior parietal lobule. In the MTL region, we observed monotonic decreases in activity across trials in the parahippocampal cortex as well as the anterior perirhinal cortex. We also observed monotonic increases in activity in the posterior perirhinal cortex with increasing memory strength. In addition, we observed clear effects of pre‐experimental familiarity with the stimulus in several regions. Consistent with previously reported electrophysiological data, we found evidence for several medial temporal lobe signals carrying recency, familiarity, and novelty information. © 2008 Wiley‐Liss, Inc.
Evaluating the differential roles of the dorsal dentate gyrus, dorsal CA3, and dorsal CA1 during a temporal ordering for spatial locations task
Authors: Hunsaker Michael R. , Kesner Raymond P. 
Published: May 2008

AbstractIt has been demonstrated that the dorsal CA1 subregion of the hippocampus mediates temporal processing of information, that dorsal CA3 participates in the spatiotemporal processing of memory, and the dorsal dentate gyrus (DG) mediates spatial pattern separation. A temporal ordering of spatial locations task was developed to test the role of the dorsal DG, CA3, and CA1 for the temporal processing of spatial information with either high or low levels of spatial interference. The results indicate that animals with DG lesions showed difficulty performing the task at high levels of spatial interference, but were able to perform the task well when there was low spatial interference. Animals with lesions to CA3 did not show a preference for either spatial location presented during the study phase during the preference test, suggesting impaired spatiotemporal processing. Animals with lesions to CA1 showed a preference for a later presented spatial location over the earlier, the opposite preference to that shown by control animals. © 2008 Wiley‐Liss, Inc.
Diazodiphenylmethane and Monosubstituted Butadienes: Kinetics and a New Chapter of Vinylcyclopropane Chemistry
Authors: Ohta Akihiro , Dahl Klaus , Raab Rainer , Geittner Jochen , Huisgen Rolf 
Published: May 2008

AbstractDiazodiphenylmethane (DDM) undergoes cycloadditions to 1‐substituted buta‐1,3‐dienes exclusively at the C(3)C(4) bond. At room temperature, the N2 loss from the initially formed 4,5‐dihydro‐3H‐pyrazoles 2 is faster than the cycloaddition and furnishes the vinylcyclopropane derivatives 7 and 9 with structural retention at the C(1)C(2) bond. 2‐Substituted butadienes react with DDM at the C(3)C(4) bond to give 12; isoprene, however, affords 3,4/1,2 products in the ratio of 86 : 14. DDM is a nucleophilic 1,3‐dipole: 1‐Cyanobutadiene reacts 400 times faster than 1‐methoxybuta‐1,3‐diene (DMF, 40°). The log k2 for the additions to six 1‐substituted butadienes show a linear correlation with σp (Hammett) and ϱ=+2.9; the log k2 of five 2‐substituted butadienes are linearly related to Taft's σI (ϱ=+1.7). The structures of the vinylcyclopropanes 7, 9, and 12 are established by NMR spectra and oxidation. A cyclopropyl carbinyl cation is made responsible for the isomerization of 12, R=Ph, Me, by acetic acid to 4‐substituted 1,1‐diphenylpenta‐1,3‐dienes 25 and 29; TsOH at 200° converts 25 further to 9,10‐dihydro‐9‐methyl‐10‐phenyl‐9,10‐ethanoanthracene (27). Thermal rearrangement of 7, 9, and 12 at 200–300° produces the 3‐ or 1‐substituted 4,4‐diphenylcyclopentenes 30 and 31. These give the same mass spectra as the vinylcyclopropanes, and an open‐chain distonic radical cation is suggested as common intermediate. Besides spectroscopic evidence for the cyclopentene structures, hydrogenation and epoxidation are described; NMR data support the trans‐attack by perbenzoic acid.
Stability of Hoogsteen‐Type Triplexes – Electrostatic Attraction between Duplex Backbone and Triplex‐Forming Oligonucleotide (TFO) Using an Intercalating Conjugate
Authors: Globisch Daniel , Bomholt Niels , Filichev Vyacheslav V. , Pedersen Erik B. 
Published: May 2008

AbstractSyntheses are described for two novel twisted intercalating nucleic acid (TINA) monomers where the intercalator comprises a benzene ring linked to a naphthalimide moiety via an ethynediyl bridge. The intercalators Y and Z have a 2‐(dimethylamino)ethyl and a methyl residue on the naphthalimide moiety, respectively. When used as triplex‐forming oligonucleotides (TFOs), the novel naphthalimide TINAs show extraordinary high thermal stability in Hoogsteen‐type triplexes and duplexes with high discrimination of mismatch strands. DNA Strands containing the intercalator Y show higher thermal triplex stability than DNA strands containing the intercalator Z. This observation can be explained by the ionic interaction of the protonated dimethylamino group under physiological conditions, targeting the negatively charged phosphate backbone of the duplex. This interaction leads to an extra binding mode between the TFO and the duplex, in agreement with molecular‐modeling studies. We believe that this is the first example of an intercalator linking the TFO to the phosphate backbone of the duplex by an ionic interaction, which is a promising tool to achieve a higher triplex stability.
Constituents from Leaves of Scolopia chinensis
Authors: Lu Ya‐Nan , Xie Guang‐Bo , Bi Dan , Shi Hai‐Ming , Tu Peng‐Fei 
Published: May 2008

AbstractTwo new phenolic glycosides, scolochinenosides A and B (1 and 2), and a new flavonoid glycoside, scoloside A (3), were isolated from the leaves of Scolopia chinensis (Lour.) Clos, together with eight known compounds. The structures of the new compounds were established on the basis of chemical and spectroscopic evidences.
Crystal Structure of Akuammigine Picrate Hydrate
Authors: Laus Gerhard , Wurst Klaus 
Published: May 2008

AbstractThe single‐crystal X‐ray data of akuammigine picrate hydrate (1⋅Picr⋅H2O) confirm the relative configuration of the indole alkaloid akuammigine (1) as epiallo (Fig. 1). With reference to the known (15S)‐configuration due to biosynthesis, the absolute configuration of the other stereogenic centers is thus given by (3R,19S,20S). Four crystallographically independent molecules are observed in the asymmetric unit (Fig. 2). Each of the alkaloid cations forms H‐bonds to a H2O and a picrate anion (Fig. 3). The H2O molecules are further associated by a H‐bond as indicated by the short O⋅⋅⋅O distance (Table 2). The conformation in the solid state of the picrate hydrate is now firmly established, and a cute H‐bonding motif is observed.
Yunnandaphninines F and G, New C30 Alkaloids from Daphniphyllum yunnanense
Authors: Di Ying‐Tong , Liu Ling‐Li , Li Chun‐Shun , Zhang Yu , Zhang Qiang , Mu Shu‐Zhen , Sun Qian‐Yun , Yang Fu‐Mei , Liu Hai‐Yang , Hao Xiao‐Jiang 
Published: May 2008

AbstractEight C30 Daphniphyllum alkaloids, including two new ones, yunnandaphninines F and G (1 and 2, resp.), were isolated from the leaves and stems of Daphniphyllum yunnanense. Their structures were elucidated on the basis of the spectroscopic data.
Triterpenoids from the Mangrove Plant Hibiscus tiliaceus
Authors: Feng Chao , Li Xiao‐Ming , Ji Nai‐Yun , Wang Bin‐Gui 
Published: May 2008

AbstractThree new triterpenoids with the rarely occurring nigrum skeleton, namely (20E)‐22‐hydroxynigrum‐20‐en‐3‐one (1), 21β‐hydroxynigrum‐22(29)‐en‐3‐one (2), and 21α‐hydroxynigrum‐22(29)‐en‐3‐one (3), were isolated from the mangrove plant Hibiscus tiliaceus. Additionally, five known triterpenoids including friedelin (4), 12‐oleanen‐3β‐ol (5), 3β‐hydroxy‐12‐oleanen‐28‐oic acid (6), 20(29)‐lupen‐3β,28‐diol (7), and cucurbita‐5,23‐dien‐3β,25‐diol (8) were also isolated and identified. The latter structures were elucidated by a detailed NMR and MS analyses, as well as by comparison with reported literature data.
Six New Cembranolides from the Hainan Soft Coral Lobophytum sp.
Authors: Chen Si‐Han , Guo Yue‐Wei , Huang Hui , Cimino Guido 
Published: May 2008

AbstractSix new cembrane diterpenes, lobophytolides A–F (1–6, resp.), along with six known related cembranoids, 7–12, were isolated from the Hainan soft coral Lobophytum sp. Their structures, including their relative configuration, were elucidated by extensive analyses of the spectroscopic data and by comparison with related known compounds.
Correlation of Hydrolysis and Desilylation of 2‐[(Trimethylsilyl)methyl]acrylate Derivatives in Aqueous Alkali Solutions
Authors: Kuroda Chiaki , Sunakawa Takeshi , Muguruma Yuichi 
Published: May 2008

AbstractHydrolysis and desilylation reaction of 2‐[(trimethylsilyl)methyl]acrylate (=2‐[(trimethylsilyl)methyl]prop‐2‐enoate) derivatives were studied to evaluate the effect of the presence/absence of a further conjugating substituent (Schemes 3 and 4 and Tables 1 and 2). The substrates having a nonconjugating substituent at the acrylate moiety were stable to dilute alkali conditions, and afforded simple hydrolysis products under concentrated alkali conditions. In contrast, both hydrolysis and desilylation occurred from the substrates bearing conjugated substituents at the acrylate skeleton. The difference in reactivity can be explained in terms of the stabilization of the intermediate anion.
Five New Xanthenone O‐Glycosides from the Roots of Polygala sibirica L.
Authors: Zhou Yu‐Hong , Jiang Yong , Shi Hai‐Ming , Chen Yu‐Ping , Tu Peng‐Fei 
Published: May 2008

AbstractFive new xanthenone O‐glycosides, sibiricaxanthone C (1), sibiricaxanthone D (2), sibiricaxanthone E (3), sibiricaxanthone F (4), and sibiricaxanthone G (5) were isolated from the roots of Polygala sibirica L., together with the six known xanthenone glycosides 6–11. The structures of new compounds were elucidated on the basis of spectral data and acid hydrolysis.
Daphnoldines A and B, Two New Yuzurine Alkaloids with a Four‐Ring System, from the Fruits of Daphniphyllum oldhami
Authors: Zhang Qiang , Di Ying‐Tong , Liu Hai‐Yang , Kong Ning‐Chuan , Gao Suo , Li Chun‐Shun , Zhang Yu , Li Shun‐Lin , Hao Xiao‐Jiang 
Published: May 2008

AbstractTwo new yuzurine alkaloids, daphnoldines A (1) and B (2), possessing a rare four‐ring system, were isolated from the fruits of Daphniphyllum oldhami. Their structures were established on the basis of extensive spectroscopic analyses. Daphnoldine A (1) is the first example of Daphniphyllum alkaloids bearing a hydroxymethyl group at C(14).
Five New Eremophilane Sesquiterpenes from Ligularia przewalskii
Authors: Xu Ji‐Qing , Hu Li‐Hong 
Published: May 2008

AbstractFive new eremophilane‐type sesquiterpenes, 3β‐(acetyloxy)‐7‐hydroxynoreremophila‐6,9‐dien‐8‐one (1), 8β‐hydroxy‐2‐dehydroxyliguhodgsonal (2), 3β‐(acetyloxy)‐11‐methoxy‐8‐oxoeremophila‐6,9‐dien‐12‐oic acid (3), 3β‐(acetyloxy)‐11‐(2′‐methylbutanoyloxy)‐8‐oxoeremophila‐6,9‐dien‐12‐oic acid (4), and 3β‐(acetyloxy)‐6α‐hydroxyligularenolide (5), along with the three known compounds 6–8, were isolated from the roots of Ligularia przewalskii. The structures of the new compounds were elucidated through spectral studies including HR‐EI‐MS, IR, and NMR data.
Cassane‐Type Diterpenoids from the Seeds of Caesalpinia magnifoliolata
Authors: Yin Yinhua , Ma Lei , Hu Li‐Hong 
Published: May 2008

AbstractTwo novel cassane‐type diterpenes, named magnicaesalpin (1) and neocaesalpin O (2), together with three known compounds, caesalmin D (3), caesalmin E (4), and neocaesalpin L (5), were isolated from the MeOH extract of seeds of Caesalpinia magnifoliolata Metc. Their structures were determined by spectroscopic methods, (1D‐ and 2D‐NMR, HR‐EI‐MS) and X‐ray analysis, as well as by comparison of their spectral data with those of related compounds.
Two New Furanoid Diterpenoids from Tinospora sagittata
Authors: Shi Lin‐Mei , Li Rong‐Qun , Liu Wen‐Hong 
Published: May 2008

AbstractTwo new clerodane‐based furanoid diterpenoids, tinosagittones A and B (1 and 2, resp.), were isolated from the roots of Tinospora sagittata, together with five known diterpenoids, i.e., columbin (3), its glucoside palmatoside C (4), isocolumbin (5), 6‐hydroxycolumbin (6), and tinophylloloside (7). Their structures were established by mass spectrometry and spectroscopic methods, especially 2D‐NMR techniques.