bluuebunny/crossref_metadata_2025_split huggingface dataset:
Complex contaminant exposure in cetaceans: A comparative E-Screen analysis of bottlenose dolphin blubber and mixtures of four persistent organic pollutants
Authors: Yordy Jennifer E. , Mollenhauer Meagan A.M. , Wilson Rachel M. , Wells Randall S. , Hohn Aleta , Sweeney Jay , Schwacke Lori H. , Rowles Teri K. , Kucklick John R. , Peden-Adams Margie M. 
Published: June 2010

Abstract
Cetaceans are federally protected species that are prone to accumulate complex mixtures of persistent organic pollutants (POPs), which individually may exert estrogenic or antiestrogenic effects. In the present study it was assessed whether contaminant mixtures harbored by cetaceans are estrogenic or antiestrogenic using a comparative approach. Interactions of antiestrogenic and estrogenic compounds were first investigated with the E-Screen assay using a mixture of four POPs (dichlorodiphenyldichloroethylene [4,4′-DDE], trans-nonachlor, and polychlorinated biphenyls [PCBs] 138 180) prevalent in cetacean blubber. Estrogenic/antiestrogenic activity was determined for the individual compounds and their binary, tertiary, and quaternary combinations. Significantly different responses were observed for the various POP mixtures, including enhanced estrogenic and antiestrogenic effects and antagonistic interactions. These results were then compared to the concentrations and estrogenic/antiestrogenic activity of contaminant mixtures isolated directly from the blubber of 15 bottlenose dolphins (Tursiops truncatus) collected from five U.S. Atlantic and Gulf of Mexico locations. The lowest observed effect concentrations (LOECs) determined for 4,4′-DDE (20 µmol/L), PCB 138 (20 µmol/L), PCB 180 (21 µmol/L), and trans-nonachlor (3 µmol/L) in the E-Screen were greater than estimated dolphin blood concentrations. Although estimated blood concentrations were below the LOECs, significant estrogenic activity was detected in diluted dolphin blubber from Cape May, NJ and Bermuda. Positive correlations between blubber estrogenicity and select POP concentrations (ΣDDTs, ΣPBDEs, ΣHCB, Σestrogenic PCBs, Σestrogenic POPs) were also observed. Collectively, these results suggest that select bottlenose dolphin populations may be exposed to contaminants that act in concert to exert estrogenic effects at biologically relevant concentrations. These observations do not necessarily provide direct evidence of endocrine disruption; however, they may indicate an environmental source of xenoestrogenic exposure warranting future research. Environ. Toxicol. Chem. 2010;29:2143–2153. © 2010 SETAC
Expression of p53, MDM2, p21, heat shock protein 70, and HPV 16/18 E6 proteins in oral verrucous carcinoma and oral verrucous hyperplasia
Authors: Lin Hung‐Pin , Wang Yi‐Ping , Chiang Chun‐Pin 
Published: June 2010

AbstractBackgroundOral verrucous hyperplasia is a precancerous lesion of oral verrucous carcinoma.MethodsThis study used immunohistochemistry to examine the expression of p53, murine double minute 2 (MDM2), p21, heat shock protein 70 (HSP 70), and human papillomavirus (HPV) 16/18 E6 proteins in 48 oral verrucous carcinoma and 30 oral verrucous hyperplasia samples.ResultsThe mean labeling indices of p53, MDM2, p21, HSP 70, and HPV 16/18 E6 proteins in oral verrucous carcinoma samples were 21%, 31%, 7%, 17%, and 0.5%, respectively, and those in oral verrucous hyperplasia samples were 19%, 35%, 11%, 14%, and 0.3%, respectively.ConclusionsImmunohistochemistry with the above‐cited 5 biomarkers could not help differentiate oral verrucous hyperplasia from oral verrucous carcinoma. The low expression of p21 may partially explain abnormal epithelial overgrowth in both verrucous lesions. The pathogenesis of both verrucous lesions may be at least partially attributed to the overexpression of MDM2 protein and moderate expression of HSP 70 protein in both lesions. © 2010 Wiley Periodicals, Inc. © 2010 Wiley Periodicals, Inc. Head Neck, 2010
Multi‐photon resonance enhancement of third harmonic generation in human oxyhemoglobin and deoxyhemoglobin
Authors: Chang Chieh‐Feng , Yu Che‐Hang , Sun Chi‐Kuang 
Published: June 2010

AbstractCancer cells require excessive oxygen and nutrition to support their rapid growth, so angiogenesis and decrease of blood oxygen are often associated with areas of cancer development. Current technologies for blood oxygen measurement, however, do not possess high spatial resolution and therefore cannot be used to detect small tumors in their early stage. In this paper, we studied the third harmonic generation (THG) spectra of oxy‐ and deoxyhemoglobin in the 1170–1365 nm region, which is strongly influenced by the multi‐photon resonance effect, especially around the Soret transition band. Our spectroscopic results thus indicate the high potential of THG spectroscopic microscopy for oxygen depletion level measurement of a single red blood cell in vivo. (© 2010 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Rubber‐toughening of dimethacrylate dental composite resin
Authors: Lee Valerie A. , Cardenas H. Lee , Rawls H. Ralph 
Published: June 2010

AbstractDimethacrylate dental composite resins exhibit inherently low toughness. Toughening of these materials may reduce the incidence of marginal and bulk fracture of composite restorations.Objective: To determine if dimethacrylate dental restorative materials can be rubber‐toughened, and if so, to identify a possible mechanism.Methods: A filler composed of aggregates of polybutadiene/silica as well as irregularly‐shaped silica slabs was produced by mixing silica with polybutadiene in dichloromethane. The dried filler was subsequently ground and sieved to <25 μm. Polybutadiene/silica ratios were varied from 0:1 (control) to 0.5:1. EDAX analysis verified the composition of the complex filler. Filler was added to a bis‐GMA/bis‐EMA/TEGDMA resin system and fractured in three‐point bend test mode at a crosshead speed of 1 mm/min. In addition, 1 bar was fractured at a crosshead speed of 0.001 mm/min to identify a possible mechanism for toughening.Results: In specimens fractured at 1 mm/min, flexural modulus is increased or maintained and flexural strength and energy to break increase as the amount of polybutadiene in the aggregates increases. Cavitation of high‐rubber‐containing aggregates is demonstrated. In the one specimen fractured at 0.001 mm/min, a marked increase in size of high‐rubber‐containing aggregates along with severe shear damage in the surrounding matrix is shown, suggesting that cavitation with subsequent absorption of energy during shear yielding is the likely mechanism behind the increase in energy to break in bars fractured at 1 mm/min.Significance: These results indicate that dimethacrylate dental composite materials can be rubber toughened, which may potentially reduce marginal and bulk fractures of composite restorations, and consequently extend their service lifetime. © 2010 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 2010.
Reduction of hexavalent chromium by Bacillus sp. isolated from chromite mine soils and characterization of reduced product
Authors: Dhal Biswaranjan , Thatoi Hrudayanath , Das Nigamananda , Pandey Bansi Dhar 
Published: June 2010

AbstractBACKGROUND: The reduction of highly mobile and toxic hexavalent chromium by bacterial strains is considered to be a viable alternative to reduce Cr(VI) contamination, in soils and water bodies, emanating from the overburden dumps of chromite ores and mine drainage. The present study reports the isolation of Cr(VI) resistant bacterial strains from an Indian chromite mine soil and their potential use in reduction of hexavalent chromium.RESULTS: Among the isolates, a bacterial strain (CSB‐4) was identified as Bacillus sp. based on standard biochemical tests and partial 16SrRNA gene sequencing, which was tolerant to as high as 2000 mg L−1 Cr(VI) concentration. The strain was capable of reducing Cr(VI) to Cr(III) in different growth media. Under the optimized conditions pH ∼7.0, 100 mg L−1 Cr(VI), 35 °C temperature and stirring speed 100 rpm, CSB‐4 reduced more than 90% of Cr(VI) in 144 h. The time course reduction data fitted well an exponential rate equation yielding rate constants in the range 3.22 × 10−2 to 6.5 × 10−3 h−1 for Cr(VI) concentration of 10–500 mg L−1. The activation energy derived from temperature dependence rate constants between 25 and 35 °C was found to be 99 kJ mol−1. The characterization of reduced product associated with bacterial cells by SEM‐EDS, FT‐IR and XRD was also reported.CONCLUSION: Reasonably high tolerance and reduction ability of indigenous Bacillus sp. (CSB‐4) for Cr(VI) under a wide range of experimental conditions show promise for its possible use in reclamation of chromite ore mine areas including soils and water bodies. Copyright © 2010 Society of Chemical Industry
Development of an efficient electroflocculation technology integrated with dispersed‐air flotation for harvesting microalgae
Authors: Xu Ling , Wang Feng , Li Hua‐Zhong , Hu Zan‐Min , Guo Chen , Liu Chun‐Zhao 
Published: June 2010

AbstractBACKGROUND: Various methods, including centrifugation, filtration, electroflocculation, flocculation and flotation, have been developed for harvesting microalgae. However, some economic or technical problems still remain with current methods for algal recovery, such as high capital, energy and running costs, flocculant toxicity or low separation efficiency. Therefore, there is great interest in developing new efficient approaches for harvesting microalgae.RESULT: An efficient electroflocculation method integrated with dispersed‐air flotation has been developed for harvesting Botryococcus braunii. The recovery efficiency of B. braunii reached 93.6% after 30 min using an electroflocculation process. Microalgae recovery was improved significantly when the electroflocculation process was integrated with dispersed‐air flotation; the recovery efficiency of B. braunii reached 98.9% after 14 min.CONCLUSION: The present work demonstrated that electroflocculation integrated with dispersed‐air flotation is a promising method suitable for microalgae harvesting. The strategic air supply obviously shortened the algal recovery time in the process of electroflocculation due to facilitating algal aggregation and flotation to the solution surface. Copyright © 2010 Society of Chemical Industry
Synthesis of Sphingosine Relatives, XVII! Synthesis of (2S,2' R,3R,3' E,4E,8E)‐1‐O‐(β‐D‐Glucopyranosyl)‐N‐(2'‐hydroxy‐3'‐octadecenoyl)‐9‐methyl‐4,8‐sphingadienine (Pen II), the Major Cerebroside Isolated from Penicillium funiculosum as the Fruiting‐Inducer Against Schizophyllum commune
Authors: Mori Kenji , Uenishi Keiji 
Published: June 2010

AbstractPen II [(2S,2' R,3R,3' E,4E,8E)‐1‐O‐(β‐D‐glucopyranosyl)‐N‐(2'‐hydroxy‐3'‐octadecenoyl)‐9‐methyl‐4,8‐sphingadienine], the major component of the cerebrosides isolated from Penicillium funiculosum A‐1 as the fruiting inducer against Schizophyllum commune, was synthesized by starting from D‐glucose, L‐serine, (2R,3E)‐2‐(tert‐butyldiphenylsilyloxy)‐3‐octadecenoic acid, and (E)‐6‐methyl‐5‐pentadecen‐1‐yne.
Diastereo‐ and Enantioselective Synthesis of 1,2‐Amino Alcohols and Protected α‐Hydroxy Aldehydes from Glycol Aldehyde Hydrazones
Authors: Enders Dieter , Reinhold Ulrich 
Published: June 2010

AbstractStarting from chiral glycol aldehyde hydrazones (S)‐2, we prepared differently protected α‐hydroxy aldehydes (R)‐ or (S)‐4 as well as N‐acetyl‐protected 1,2‐amino alcohols (R)‐11 in high enantiomeric excesses via azaenolate α‐alkylation or nucleophilic 1,2‐addition to the CN double bond. The successive introduction of two vicinal stereogenic centres opens a new, flexible syn‐diastereo‐ and enantioselective route to functionalised, N‐acetyl‐protected, vicinal amino alcohols (R,R)‐13, which was demonstrated in the case of the γ‐amino‐β‐hydroxycarboxylic acid statin (R,R)‐15 and its analogues B.
Antibiotics from Gliding Bacteria, LXXIII Indole and Quinoline Derivatives as Metabolites of Tryptophan in Myxobacteria
Authors: Böhlendorf Bettina , Bedorf Norbert , Jansen Rolf , Trowitzsch‐Kienast Wolfram , Höfle Gerhard , Forche Edgar , Gerth Klaus , Irschik Herbert , Kunze Brigitte , Reichenbach Hans 
Published: June 2010

AbstractTwo groups of 3‐substituted indole 1, 6–9 as well as 4‐substituted quinoline derivatives 2–5 and harman (10) were isolated from various species and genera of myxobacteria. They were identified by their spectroscopic data. Some of the metabolites show moderate antifungal activity. Their biosynthetic origin in myxobacteria was demonstrated for 1, 2, and 3 by incorporation of L‐[1'‐14C]tryptophan.
Electroorganic Synthesis, 62!! Anodic Heterocoupling (Mixed Kolbe Electrolysis) of Carbohydrate Carboxylic Acids with Alkanoic Acids to C‐Glycosides
Authors: Harenbrock Michael , Matzeit Agnes , Schäfer Hans J. 
Published: June 2010

Abstract2‐Deoxy carbohydrate carboxylic acids 1–3 were prepared from glucal 4, acetobromoglucose 5, and D‐galactose (7), respectively. The acids 1–3 were electrolyzed with different coacids at controlled current in methanol at platinum electrodes in an undivided cell to afford C‐glycosides as heterocoupling products in 46–70% yield. Compound 28, obtained by deacylation of 17, has a critical micelle concentration (cmc) of 2.4 mM, which is about 2.5 times lower than that of the corresponding O‐glycoside 29. Compound 28 forms liquid crystals with a smectic A phase in the range between 96 and 190°C, which is twice as large as that of 29. Compounds 31 and 32, obtained by deprotection of 23 and 24, respectively, also exhibit liquid crystalline behavior.
Enantioselective Diels‐Alder Reactions: NMR Spectroscopy of a Chiral Titanium Lewis Acid under High Pressure
Authors: Tietze Lutz F. , Ott Christian , Frey Urban 
Published: June 2010

Abstract1H‐NMR investigations of the temperature and pressure dependence of the equilibrium of the reaction of the tartaric acid derivative 7 with titanium dichloride diisopropoxide (8) to give the chiral Lewis acid 9 show that increasing pressure and temperature shift the equilibrium to the achiral Lewis acid 8. The observed decrease in enantioselectivity of the cycloaddition reaction of isoprene (3) with 3‐crotonyl‐1,3‐oxazolidin‐2‐one (4) in the presence of 7 and 8 under high pressure may therefore be attributed at least in part to the unfavorable influence of pressure on the formation of 9.
Synthesis of (1S,5S)‐4,5‐Dihydro‐1,5‐epoxy‐1H‐2‐benzoxocin‐6(3H)‐one from (S)‐Malic Acid Derivatives
Authors: Wünsch Bernhard , Diekmann Heike 
Published: June 2010

AbstractThe homochiral 1,3‐dioxanes 8a–e with a 2‐bromophenyl substituent in position 2 and an electrophilic group in position 4 were stereo‐ and regioselectively prepared from the (S)‐malic acid derivatives 6a, 6b, 11, and 14. Attempts to prepare the tricycles 5a–c by connecting the 2‐phenyl substituent with the electrophilic groups in position 4 of 8a–e in a Parham cyclization across the 1,3‐dioxane ring failed. The synthesis of the tricyclic title ketone 5a succeeded, however, by addition of the lithiated benzaldehyde acetal 7c to the protected α‐hydroxylactone 10b and subsequent treatment of the intermediate ketone 23 with acid. The acid hydrolysis of the alcohol 26, which was obtained by addition of 7c to the protected dihydroxy aldehyde 25b, followed by oxidation of the resulting alcohols 27a and b represent a second possibility for the preparation of the tricyclic ketone 5a.
Lintenolides C–E: Unusual Antifeedant Sesterterpenes Isolated from the Marine Sponge Cacospongia cf. linteiformis
Authors: Carotenuto Alfonso , Fattorusso Ernesto , Magno Silvana , Mayol Luciano , Lanzotti Virginia 
Published: June 2010

AbstractIn addition to the previously described lintenolides A and B (3a, b and 4a, b), the marine sponge Cacospongia cf. linteiformis was also found to produce the three new lintenolides C (7a, b), D (8a, b) and E (9a, b), all possessing the same highly antifeedant activity previously found in lintenolides A and B. The stereostructures of the metabolites were mainly elucidated by extensive NMR studies.
Ring Opening Reactions of Iminoaziridines and Aminoazirinium Ions. Is Electrocyclic Ring Opening of 2H‐Azirinium Ions a Myth?
Authors: Quast Helmut , Aldenkortt Sven , Freudenreich Bernd , Schäfer Peter , Peters Eva‐Maria , Peters Karl , von Schnering Hans Georg , Würthwein Ernst‐Ulrich 
Published: June 2010

AbstractTreatment of the 3,3‐dimethyl‐2‐iminoaziridine 7 with hydrogen bromide yields similar amounts of the α‐bromo amidine 10a · HBr and the α,β‐unsaturated amidinium bromide 11. Ring opening reactions of the 3‐tert‐butyl‐2‐iminoaziridines 8 by nucleophiles (potassium methoxide, Pirkle's alcohol 13, and 4‐nitrophenol) are sluggish affording the α‐amino imidates 12, 14, and 15, respectively. Compound 15a isomerises via the Meisenheimer‐type intermediate 16 to furnish the α‐amino amide 17. Methyl triflate converts (R)‐8 into the 2‐tert‐butyl‐3‐amino‐2H‐azirinium triflates (R)‐18 which do not undergo racemisation as shown after hydrolysis to yield the α‐amino amides (R)‐20. In a similar sequence, (R)‐8a and b are converted into the α‐amino amides (R)‐26 by the action of hydrogen halides or 4‐toluenesulfonic acid hydrate followed by hydrolysis of the intermediate imidoyl derivatives (R)‐24. Retention of configuration is observed after treatment of (R)‐8a with hydrogen chloride and of (R)‐8b with hydrogen bromide. Some racemisation found in the other cases is supposed to involve (R)‐24 but not the aminoazirinium ions (R)‐8 · HX. In a side reaction, 8a and b decompose into methyl isocyanide (22) and the imines 23 at low temperatures, probably under general acid catalysis. The results are not consistent with the hypothesis of an electrocyclic ring opening of 3‐amino‐2H‐azirinium ions to afford 2‐amino‐1‐azaallyl cations (= α‐imino carbocations). – The heat of protonation of the parent compounds (E)‐27, (Z)‐27, 30 and the structures and energies of the resulting cations (E)‐28, (Z)‐28, 29, and 31 were calculated by ab initio methods. Complete geometry optimisations were performed with the RHF/6‐31 + G** basis set. Energies were calculated on the RHF, MP2, MP4SDTQ, and CCSD(T) levels. According to the geometric parameters, the amidine delocalisation of the free bases is abondened in the cations (E)‐28, (Z)‐28, and 31 while it is considerably strengthened in 29. In accord with these geometric changes, 29 is by far the most stable protonated species followed by (E)‐ and (Z)‐28. Azirine 31 is much higher in energy. The calculated difference in (gas phase) basicity between the two nitrogen atoms of iminoaziridines appears to exclude the ring‐protonated cations as intermediates also for reactions in solution.
Two New Guaiadiene Derivatives Isolated from Thuja occidentalis L. Wood Oil
Authors: Weyerstahl Peter , Marschall Helga , Collin Guy 
Published: June 2010

AbstractTwo new guaiadiene derivatives, the ether 9α, 11‐epoxy‐1βH,5αH,7βH‐guaia‐3,10(14)‐diene (4) and the corresponding alcohol 1βH,5αH,7βH‐guaia‐3,10(14)‐dien‐11‐ol (8) were isolated from the essential oil from the heartwood of Thuja occidentalis L. Their structures were elucidated by 1H‐ and 13C‐NMR spectroscopy (COSY, NOED).
Synthesis of (±)‐Azaascorbic Acid
Authors: Stachel Hans‐Dietrich , Zeitler Klaus , Dick Stefan 
Published: June 2010

AbstractThe synthesis of the hitherto unknown aza analog of ascorbic acid (±)‐10a is described. Aldol type reaction of the tetramic acid derivative 4 with tert‐butyldimethylsilyloxy acetaldehyde furnished a mixture of the aldol (±)‐5b and the diastereomeric O‐Boc protected aldols (±)‐6a and (±)‐6b. By X‐ray structural analysis the major reaction product was shown to be the threo isomer 6a. Desilylation of 6a led to the alcohol 7. Removal of the remaining protective groups yielded racemic azaascorbic acid 10a. Similar deprotection of the aldol 5b led only to impure azaisoascorbic acid (±)‐10b which was characterized as the dimethyl ether 12b.
Intramolecular [2 + 2] Photocycloaddition of 2‐Allylindane‐1‐thiones
Authors: Nishio Takehiko , Okuda Norikazu , Kashima Choji 
Published: June 2010

AbstractThe photochemical reactions of indane‐1‐thiones 4 were examined. Irradiation of indane‐1‐thiones 4c–d bearing δ‐hydrogen atoms in the side chain gave cyclic thiol derivatives 5c–d via δ‐hydrogen atom abstraction by the excited thiocarbonyl sulfur. Irradiation of 2‐allylindane‐1‐thiones 4e–h afforded the multifused thietanes 7e–h by intramolecular [2 + 2] cycloaddition between CS and CC bonds.
Synthesis of Thione Analogues of Monobactams
Authors: Nieschalk Jens , Schaumann Ernst 
Published: June 2010

AbstractOptically active β‐lactams 4 were treated with Lawesson's reagent (2) or Davy's reagent (3) to give the β‐thiolactams 5. Demethylation of 5 by reduction with dissolved metal gave the 1‐unsubstituted 2‐azetidinethiones 6 which were sulfonated and Boc‐deprotected to provide (3S)‐amino‐2‐thiomonobactamic acids 8. The side chain on nitrogen was introduced by using 1‐hydroxybenzotriazole‐activated acids 9. Deprotection of functional groups in the side chain yielded the β‐thiolactam analogues 11a, 11b of SQ 81,377 and aztreonam (1). These compounds were found to be weakly active against a range of Gram‐negative bacteria.
Synthesis of (—)‐Malyngolide
Authors: Flörke Holger , Schaumann Ernst 
Published: June 2010

Abstractδ‐Lactone (–)‐malyngolide (1) was synthesized by starting from the optically active epoxide 5. Coupling of derivative 3 with propargyl anion 11 and subsequent metal‐catalyzed methylation of the triple bond provided 14 incorporating all the carbon atoms of 1. Cyclization to the acetal 16 was achieved via the epoxidation product 15. Adjustment of the oxidation state and removal of protective groups complete the synthesis of 1.
Pseudosugars, 36. Synthesis of Methyl 5a′‐Carbamaltoses Linked by Imino, Ether and Sulfide Bridges and Unsaturated Derivatives Thereof
Authors: Tsunoda Hidetoshi , Sasaki Shin‐Ichi , Furuya Takashi , Ogawa Seiichiro 
Published: June 2010

AbstractMethyl 5a′‐carbamaltoses linked by imino, ether, and sulfide bridges were synthesized by coupling of an amino carbasugar with a sugar epoxide and of the carbasugar epoxide with the oxide anion or thioacetate derived from sugar derivatives. Their unsaturated derivatives related to a potent α‐glucosidase inhibitor, methyl acarviosin, were also synthesized. Moderate inhibitory activity against baker's yeast α‐glucosidase was observed only for the imino‐linked compounds 2 and 5.