bluuebunny/crossref_metadata_2025 huggingface dataset:
ChemInform Abstract: The Synthesis of Ketomethylene Pseudopeptide Analogues of Dipeptide Aldehyde Inhibitors of Calpain.
Authors: Angelastro Michael R. , Marquart Angela L. , Mehdi Shujaath , Koehl Jack R. , Vaz Roy J. , Bey Philippe , Peet Norton P.
Published: June 2010

ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.
ChemInform Abstract: An Efficient Stereoselective Synthesis of Enantiomerically Pure Aziridine Derivatives of Allyl β‐D‐Glucopyranosides Asymmetrically Induced by a Glucide Moiety.
Authors: Chiappe Cinzia , Crotti Paolo , Menichetti Elena , Pineschi Mauro
Published: June 2010

ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.
ChemInform Abstract: Sigmatropic Rearrangement of Uronic Acid Derived Saccharide Allyl Ketene Acetals. A Study of Stereochemistry and Structural Limitations.
Authors: Werschkun Barbara , Thiem Joachim
Published: June 2010

ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.
ChemInform Abstract: Synthesis of Unusual Bridged Steroid Alkaloids by an Iminium Ion Induced 1,5‐Shift of a Benzylic Hydride.
Authors: Woelfling Janos , Frank Eva , Schneider Gyula , Tietze Lutz F.
Published: June 2010

ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.
ChemInform Abstract: Combining Four Different Model Nucleobases (Uracil, Adenine, Guanine, Cytosine) via Metal Binding and H Bond Formation in a Single Compound.
Authors: Sigel Roland K. O. , Thompson Susan M. , Freisinger Eva , Lippert Bernhard
Published: June 2010

ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.
ChemInform Abstract: (R)‐(‐)‐ and (S)‐(+)‐Synadenol: Synthesis, Absolute Configuration, and Enantioselectivity of Antiviral Effect.
Authors: Zemlicka Jiri , ET AL. ET AL.
Published: June 2010

ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.
ChemInform Abstract: Study on Fungitoxic 3‐Amino‐2‐piperidinone‐containing Lipids: Revised Structure of Cepaciamide A and Structural Determination of Its Closely Related Lipid, Cepaciamide B.
Authors: Toshima Hiroaki , Maru Kazuko , Jiao Ying , Yoshihara Teruhiko , Ichihara Akitami
Published: June 2010

ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.
ChemInform Abstract: Study on Fungitoxic 3‐Amino‐2‐piperidinone‐containing Lipids: Total Syntheses of Cepaciamides A and B.
Authors: Toshima Hiroaki , Maru Kazuko , Saito Masatoshi , Ichihara Akitami
Published: June 2010

ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.
ChemInform Abstract: New Minimal Substrate Structural Requirements in the Enzymatic Peroxidation of Alkenes with Soybean Lipoxygenase.
Authors: Novak Mark J.
Published: June 2010

ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.
ChemInform Abstract: Stereoselective Synthesis of the Antifungal Antibiotic (+)‐Preussin.
Authors: Veeresa G. , Datta Apurba
Published: June 2010

ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.
ChemInform Abstract: Simultaneous Oxide and Metal Removal from Silicon Surfaces.
Authors: Robertson III E. A. , Beck S. E. , George M. A. , Bohling D. A. , Waskiewicz J. L.
Published: June 2010

ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.
ChemInform Abstract: Sol—Gel Preparation of Pb(Zr0.50Ti0.50)O3 Ferroelectric Thin Films Using Zirconium Oxynitrate as the Zirconium Source.
Authors: Zeng Jianming , Song Shigeng , Wang Lianwei , Zhang Miao , Zheng Lirong , Lin Chenglu
Published: June 2010

ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.
ChemInform Abstract: Synthesizing Nanocrystalline Pb(Zn1/3Nb2/3)O3 Powders from Mixed Oxides.
Authors: Wang John , Dongmei Wan , Junmin Xue , Beng Ng Wei
Published: June 2010

ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.
ChemInform Abstract: Transition Metal Ions in Microporous Crystalline Aluminophosphates: Isomorphous Substitution
Authors: Weckhuysen Bert M. , Rao R. Ramachandra , Martens Johan A. , Schoonheydt Robert A.
Published: June 2010

ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.
ChemInform Abstract: Pictet—Spengler Reactions of Nb‐Hydroxytryptamines and Their Application to the Synthesis of Eudistomins
Authors: Hino Tohru , Nakagawa Masako
Published: June 2010

ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.
ChemInform Abstract: Survey of Oxygenated 2,11‐Cyclized Cembranoids of Marine Origin
Authors: Bernardelli Patrick , Paquette Leo A.
Published: June 2010

ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.
ChemInform Abstract: The Syntheses and Properties of 1,2‐Epoxyalkylphosphonates
Authors: Iorga Bogdan , Eymery Frederic , Savignac Philippe
Published: June 2010

ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.
ChemInform Abstract: A Catalytic System for Reductive Transformations via One‐Electron Transfer
Authors: Hirao Toshikazu
Published: June 2010

ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.
ChemInform Abstract: Rhodiola rosea L.: Traditional and Biotechnological Aspects of the Isolation of Medicinal Drugs
Authors: Bykov V. A. , Zapesochnaya G. G. , Kurkin V. A.
Published: June 2010

ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.
ChemInform Abstract: Lanthanoid Triflates as Unique Lewis Acids
Authors: Xie Wenhua , Jin Yafei , Wang Peng George
Published: June 2010

ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.
ChemInform Abstract: Organic Chemical Reactions in Supercritical Water
Authors: Savage Phillip E.
Published: June 2010

ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.
ChemInform Abstract: Thio‐ and Selenosugars
Authors: Anon. Anon.
Published: June 2010

ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.
ChemInform Abstract: Architectonic Neoglycoconjugates: Effects of Shapes and Valences in Multiple Carbohydrate—Protein Interactions
Authors: Zanini D. , Roy R.
Published: June 2010

ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.
ChemInform Abstract: Synthetic Studies on Glycosidase Inhibitors Composed of 5a‐Carba‐sugars
Authors: Ogawa S.
Published: June 2010

ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.
ChemInform Abstract: Issues Pertinent to the in vivo in situ Spin Trapping of Free Radicals
Authors: Pou Sovitj , Halpern Howard J. , Tsai Pei , Rosen Gerald M.
Published: June 2010

ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.
ChemInform Abstract: Site‐Selective Fluorescence Spectroscopy of Conjugated Polymers and Oligomers
Authors: Baessler Heinz , Schweitzer Bernd
Published: June 2010

ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.
ChemInform Abstract: Establishment of Microanalysis of Prostaglandin Metabolites by GC/MS and Its Clinical Application
Authors: Mizugaki Michinao
Published: June 2010

ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.
Brighter, more colorful colors and darker, deeper colors based on a theme of brilliance
Authors: Heckaman Rodney L. , Fairchild Mark D.
Published: June 2010

A methodology for achieving brighter, more colorful colors and deeper, darker colors based on Evans' zero gray (G0) [described in The Perception of Color] and his concept of brilliance as a percept in color vision was demonstrated and tested psychometrically in media produced under current digital video and digital cinema standards—basically the sRGB set of primaries. Objects or surfaces in a scene represented in sRGB as having gray content in the Evans sense are rendered as original. Flesh tones are preserved. Those features not having gray content—a highly colorful arrangement of flowers, a clear blue sky, and the glossy red lipstick of a beautiful lady—are made brighter, more colorful and deeper, darker when rendered in a set of primaries that emulate, for example, the xvYCC‐encoded standard and whose colors extend beyond those of sRGB—an expanded gamut, if you will. In all but the most‐aggressive application, versions of scenes where this methodology was applied were consistently preferred over the sRGB version across 10 representative scenes and 17 observers. © 2010 Wiley Periodicals, Inc. Col Res Appl, 2010
Improved active‐diode circuit used in voltage doubler
Authors: Jia Jingbin , Leung Ka Nang
Published: June 2010

An improved active‐diode circuit, which makes use of positive feedback to achieve fast on/off transition, is presented in this paper. The proposed active‐diode circuit can be embedded into a voltage doubler to replace the commonly used dead‐time circuit and to eliminate reverse current. In addition, the relationship between oscillation frequency, boosting and output capacitances, load‐ and on‐resistances of the power switch and the output voltage is analysed, to investigate a methodology to retain high voltage gain of a voltage doubler. The proposed active‐diode circuit is applied to a voltage doubler implemented in a commercial 0.35‐µm process with threshold voltage of about 0.68 V. The input voltage, maximum output current and oscillation frequency of the voltage doubler are 1 V, 1 mA and 0.4 MHz, respectively. Moreover, the used boosting and output capacitances are 22 nF. The highest power efficiency achieved is 83% at a load current of 0.47 mA. Copyright © 2010 John Wiley & Sons, Ltd.
Luminescence of the solid complexes of acridine orange with RNA
Authors: Kapuscinski Jan , Darzynkiewicz Zbigniew , Melamed Myron R.
Published: June 2010

The products of interaction between acridine orange (AO) and natural RNA, or the synthetic RNA homopolymers are precipitates insoluble over a wide range of ionic strength. These complexes have a composition of 1 AO molecule per 1 phosphatate. The reaction is highly cooperative and the complex exhibits metachromatic luminescence. Significant differences in the luminescence spectra, related to base composition of RNA, characterize the insoluble complexes. This observation suggests that dye‐base interactions take place in the AO‐RNA complexes.

During titration of poly(rA) with AO and simultaneous measurement of the luminescence and light scatter a two‐step formation of the particles could be detected. The cooperative binding of the ligand at D/P < 0.6 coincides with formation of small particles (molecular aggregates or micelles) and is followed at D/P > 0.6 by a cooperative agglomeration; the product of this agglomeration is particles of the size 0.35 μm and larger.

Evidence is presented that suggests that the long wavelength luminescence (∼ 650 nm) is a consequence of the solute‐solid state transition of the AO‐RNA interaction product rather than the classic dye‐dye interactions previously visualized in the stacking model. Since these novel observations cannot be fully explained by the previously postulated molecular mechanisms of AO binding, an alternative model is advanced. Its implications in quantitative cytochemistry of nucleic acid as applied to flow cytometry are discussed.
Flexible sorting decision and droplet charging control electronic circuitry for flow cytometer‐cell sorters
Authors: McCutcheon Mark J. , Miller Richard G.
Published: June 2010

We describe sorting decision and droplet charging control electronic circuitry for a flow cytometer–cell sorter. The circuitry can handle up to five independent input signals and can sort in up to four directions. A sixth input channel is used to determine the presence or absence of an event requiring analysis. Sorting decisions are stored in a read‐only memory semiconductor device. All the input signals for a given event are reexpressed as either 0 or 1 and are used to define an address in this memory which contains the desired sorting outcome for the event. A set of switches enables one to choose between many different procedures for relating input cell pulses to sorting outcomes by switching to different blocks of the memory. The circuitry has been found capable of purity of cell separation to the level permitted by “deadtime” in the preceding analog stages. It is in regular use with the Ontario Cancer Institute flow cytometer–cell sorter.
Three‐color fluorescence measurements on single cells excited at three laser wavelengths
Authors: Steinkamp John A. , Stewart Carleton C. , Crissman Harry A.
Published: June 2010

A three‐laser flow cytometer for quantitative analysis and sorting of cells and microscopic particles has been developed and evaluated using argon‐ and krypton‐ion lasers as excitation sources. Cells stained with three fluorescent dyes having different excitation spectra enter a flow chamber where they first pass through an electronic volume sensor and then intersect three spatially separated laser beams for fluorescence excitation of bound dyes and light scatter measurements. Separate pairs of beam‐shaping optics independently position and focus each beam onto the cell stream thus permitting cells to be sequentially illuminated. Fluorescence is measured by a detector that employs a single collecting lens for single or multilaser excitation experiments. Fluorescence signals are processed and displayed as frequency distribution histograms using an LSI‐11 computer. This instrument is described in detail with illustrative examples using cells stained for DNA content, protein, and cell surface antigens and cells that have phagocytized fluorescent microspheres.
Induction of chromosome damage by ultraviolet light and caffeine: Correlation of cytogenetic evaluation and flow karyotype
Authors: Cremer C. , Cremer T. , Gray J. W.
Published: June 2010

Asynchrononously growing cells of a M3‐1 Chinese hamster line were ultraviolet (UV) irradiated (λ = 254 nm) with UV fluences up to 7.5 J/m2. After irradiation, cells were incubated with or without 2 mM caffeine for 20 hr, then mitotic cells were selected by mechanical shaking. Their chromosomes were isolated, stained with Hoechst 33258 and chromomycin A3, and measured flow cytometrically. While the fluorescence distributions of chromosomes (flow karyotypes) from cells treated with UV alone or with caffeine alone were very similar to those of untreated controls, the flow karyo‐types of UV + caffeine‐treated cells showed a debris continuum that increased with increasing UV fluence suggesting an increased number of chromosome fragments. Visual evaluation of metaphase plates revealed that the percentage of cells with chromosome damage also increased steadily with increasing UV fluence. A high degree of correlation was observed between the relative magnitude of the debris level from flow karyotypes and the percentage of cells with chromosome damage and with generalized chromosome shattering, respectively, as determined from metaphase spreads.
Quantification of mammalian sperm morphology by slit‐scan flow cytometry
Authors: Benaron David A. , Gray Joe W. , Gledhill Barton L. , Lake Suzanne , Wyrobek Andrew J. , Young Ian T.
Published: June 2010

The head shapes of mammalian sperm have been measured by slit‐scan flow cytometry (SSFCM). In this approach, the distribution of fluorescence along acriflavine stained mammalian sperm is recorded and used as a measure of head shape. Fluorescence profiles were measured for sperm from mice, rabbits, hamsters, and bulls, and for sperm from mice exposed to testicular x‐irradiation from 0 to 900 rads. The profiles for sperm from nonirradiated animals were characteristic of each species and were reproducible from sperm to sperm. Some of the fluorescence profiles for sperm from the irradiated mice differed significantly from the profiles usually measured for sperm from unexposed mice. An algorithm was developed to determine the frequency of these sperm. The estimated frequencies of atypical profiles correlated well (r = 0.99) with the frequencies of abnormally shaped sperm determined by microscopic scoring. The maximum SSFCM sensitivity (minimum detectable dose = 199 rad) was not as high as that for the visual assay (minimum detectable dose = 116 rad). However, only 100 profiles were measured by SSFCM at each dose while at least 500 sperm were scored visually at each dose. The sensitivity of the SSFCM assay should be increased substantially by measuring more profiles. The objective nature of SSFCM coupled with the high correlation with results from the visually based assay of morphology suggests the use of SSFCM to measure frequencies of misshapen sperm when testing for mutagens or monitoring for effects of environmental contaminants.
A parameter for the distribution of fluorophores in cells derived from measurements of inner filter effect and reabsorption phenomenon
Authors: Tanke H. J. , van Oostveldt P. , van Duijn P.
Published: June 2010

The linear relationship between the emitted fluorescence and the amount of fluorophore at relatively high local absorbance values is significantly disturbed by two major phenomena, inner filter effect and reabsorption of fluorescence emission light. For a theoretical model in which excitation and emission rays were considered parallel and the fluorophore distribution was assumed to be homogeneous, Rigler (Acta Physiol Scand (Suppl.) 267:1, 1966) showed that these errors become significant at local absorbance >0.1 and may become more important for heterogeneously stained cells measured with conical illumination.

In this study we demonstrate theoretically and experimentally that the inner filter effect and reabsorption phenomenon depend not only on the average local absorption but also on the distribution of the fluorophore in the measuring field. The ratio of the fluorescence intensities in the longer and the shorter emission wavelength range is introduced as a new parameter called the “heterogeneity index.” This index is not affected by the total amount of fluorophore, but depends on the fluorophore distribution within the measuring field.

The theory has been tested on Sephadex beads and glycoprotein films stained with periodic acid acriflavine‐SO2 or acrolein acriflavine‐SO2. The results of the measurements on the model systems were found to be qualitatively in agreement with the theoretical predictions.

Heterogeneity index measurements on Feulgen acriflavine‐SO2 stained cells using both microscope fluorometry and flow cytometry showed significant differences for cell nuclei with the same total amount of fluorophore but with different fluorophore distributions. The avoidance of inner filter effect and reabsorption phenomenon or their use to study changes in DNA compactness such as occur during cell differentiation and degeneration are discussed.
Biophysical identification and sorting of high metastatic variants from B16 melanoma tumor
Authors: Lessin Stuart R. , Abraham Samuel R. , Nicolini Claudio
Published: June 2010

Chromatin structure, in terms of higher order nuclear‐DNA condensation (scanning cytometry) and in terms of acridine orange primary binding sites (flow cytometry), is analyzed and shown to be significantly different between high (B16‐F10) and low (B16‐F1) metastatic variants of B16 melanoma. Furthermore, double staining of B16‐F10 and B16‐F1 with ethidium bromide (chromatin) and fluorescamine (membranes) provides the identification of a homogeneous subpopulation of cells with enhanced metastatic potential based on differential fluorescamine uptake. Fluorescamine uptake and poststaining viability is shown to be dependent upon the dye/cell ratio at which staining occurs. Utilizing a sterile cell sorting technique, a subpopulation of B16‐F10 with increased fluorescamine uptake representing 30% of the total “intact cell” population was isolated by means of a fluorescence activated cell sorter and replated in vitro. This subpopulation when assayed in vivo produced significantly more pulmonary metastases than its parent cell line. Scanning cytometry of the Feulgen stained sorted subpopulation reveals that the cells possess a unique nuclear morphometry characterized by a 2C‐3C DNA content and a large nuclear area (disperse chromatin). Finally, when we assay simultaneously for nuclear‐DNA organization and cell membrane organization a progressive uncoupling between nuclear and cell morphometry is apparent in B16‐F10 (versus B16‐F1).
Stage‐related variations in DNA fluorescence distribution during rat spermatogenic cycle measured by flow cytometry
Authors: Clausen O. P. F. , Parvinen M. , Kirkhus Bente
Published: June 2010

Living segments of rat seminferous tubules representing the fourteen stages of the spermatogenic cycle have been isolated for DNA flow cytometry using the transillumination‐assisted microdissection procedure. The resulting DNA profiles showed stage‐related variations in the proportions of cells within the haploid (1C), diploid (2C) and tetraploid (4C) classes. Three distinct populations of haploid cells could be distinguished according to differences in fluorescence intensity of their nuclear DNA. The major haploid peak (1C) was found to reflect the steps 1–11 spermatids, the first hypofluorescent peak (fluorescence intensity from 0.45–0.75C) the steps 12–15 spermatids and the second hypofluorescent peak (fluorescence intensity of ca. 0.25C) the maturing steps 16–19 spermatids. The changes in fluorescence intensity could thus be correlated with nuclear protein transitions that are known to occur during spermiogenesis in rats. The results indicate that the processes responsible for the changes in nuclear fluorescence intensities are rapidly occurring, although not synchronously in all spermatids at the same developmental stages.
Reactions of 1,2,4‐Trithiolane and Its 4‐S‐Oxide with Diphosphane Pt0 Complexes
Authors: Petzold Holm , Weisheit Thomas , Bräutigam Silvio , Görls Helmar , Mloston Grzegorz , Weigand Wolfgang
Published: June 2010

Reactions of 1,2,4‐trithiolanes with Pt0 complexes often proceed via an oxidative addition of the Pt0 complex fragment into the S–S bond and subsequent extrusion of a thioketone molecule by ring contraction. The six‐membered intermediate 5a, formed in the course of the reaction of the parent 1,2,4‐trithiolane (1a) and Pt0 complex 4, was detected bymeans of low‐temperature NMR spectroscopy. Stable derivatives of this type (compounds 9, 11 and 12) were isolated either by using (dppe)Pt0 complex 8 or 1,2,4‐trithiolane 4‐S‐oxide (10). The molecular structures of platinum complexes 9, 11 and 12, as well as their unexpected stability, are discussed.
Structure and Dynamics of Lanthanide(III) Complexes with an N‐Alkylated do3a Ligand (H3do3a = 1,4,7,10‐Tetraazacyclododecane‐1,4,7‐triacetic Acid): A Combined Experimental and DFT Study
Authors: Regueiro‐Figueroa Martín , Esteban‐Gómez David , de Blas Andrés , Rodríguez‐Blas Teresa , Platas‐Iglesias Carlos
Published: June 2010

Lanthanide(III) complexes with 10‐benzyl‐1,4,7‐tris(carboxymethyl)‐1,4,7,10‐tetraazacyclododecane (H3L) have been investigated as model compounds of N‐alkylated LnIII–do3a complexes (H3do3a = 1,4,7,10‐tetraazacyclododecane‐1,4,7‐triacetic acid) with potential application in molecular imaging. The X‐ray structures of the [{Ln(L)(H2O)}4]·18H2O complexes (Ln = Eu or Tb) show that the metal ion is directly bound to the seven donor atoms of the ligand, with the nine‐coordination sphere completed by an oxygen atom of an inner‐sphere water molecule and an oxygen atom of a carboxylate group from a neighboring [Ln(L)] unit. This results in the formation of tetrameric units through the sharing of carboxylic groups between adjacent [Ln(L)(H2O)] complexes. Luminescence lifetime measurements recorded in H2O and D2O provide a number of coordinated water molecules (q) of 1.2, which indicates that the major species that exists in solution contains one inner‐sphere water molecule. The conformational properties of the [Ln(L)(H2O)] complexes (Ln = Gd or Lu) have been investigated by using density functional theory (DFT) calculations (B3LYP model). Our results indicate that the Δ(λλλλ) conformation is more stable than the Δ(δδδδ) one for both complexes. The interconversion between these two isomers may proceed either through the inversion of the five‐membered rings formed upon coordination of the 1,4,7,10‐tetraazacyclododecane (cyclen) unit, or through the stepwise rotation of the three acetate pendant arms. According to our calculations, the activation free energy for the arm‐rotation process (5.6 kcal mol–1) is much lower than that of the ring‐inversion path (14.6 kcal mol–1), which in turn is very similar to those determined experimentally for LnIII(dota) complexes. Thus, a low energy barrier for the arm‐rotation process appears to be responsible for the relatively fast isomer interconversion observed for LnIII(N‐alkylated do3a) complexes.
Facile Synthesis of Trisubstituted Allenynes by Phosphane‐Mediated Deoxygenation of 2,4‐Pentadiyn‐1‐ol
Authors: Jiang Huanfeng , Wang Wei , Yin Biaolin , Liu Weibing
Published: June 2010

A facile method for the synthesis of trisubstituted allenynes has been developed. The process involves phosphane‐mediated deoxygenation of 2,4‐pentadiyn‐1‐ol derivatives. A variety of propargyl alcohols can be transformed into allenynes in moderate to good yields under mild reaction conditions.
(9H‐Fluoren‐9‐yl)methanesulfonyl (Fms): An Amino Protecting Group Complementary to Fmoc
Authors: Ishibashi Yoshitaka , Miyata Kengo , Kitamura Masato
Published: June 2010

A sulfonamide‐based protecting group (PG), (9H‐fluoren‐9‐yl)methanesulfonyl (Fms), which can be used in a similar way to the well‐established Fmoc PG, was developed. The advantages of this new PG were demonstrated in the successful formation of a phosphonamide between an N‐Fms‐protected α‐phosphonoalanine monoester and secondary alkylamines, including (R)‐2‐phenylethylamine, (S)‐phenylalanine tert‐butyl ester (H‐Phe‐OtBu), H‐Pro‐Gly‐OtBu, and H‐Phe‐Phe‐OtBu, without formation of oxazaphospholine, which is a serious problem associated with the Fmoc PG. The success should pave the way to the solid‐phase synthesis of unnatural peptides substituted with α‐amino phosphonic acid (AP) at essentially any arbitrary position without significant modification of the Fmoc‐based chemistry that has been accumulated since Carpino's report in 1970. The N‐Fms‐AP monomer would attract much attention in the field of peptide mimetics.
Interstrand crosslink inducing agents in pretransplant conditioning therapy for hematologic malignancies
Authors: Valdez Benigno C. , Andersson Borje S.
Published: June 2010

Despite successful molecularly targeted, highly specific, therapies for hematologic malignancies, the DNA interstrand crosslinking agents, which are among the oldest and least specific cytotoxic drugs, still have an important role. This is particularly true in stem cell transplantation, where virtually every patient receives conditioning therapy with a DNA‐alkylating agent‐based program. However, due to concern about serious additive toxicities with combinations of different alkylating drugs, the last several years have seen nucleoside analogs, whose cytotoxic action follows vastly different molecular pathways, introduced in combination with alkylating agents. The mechanistic differences paired with different metabolic pathways for the respective drugs have clinically translated into increased safety without appreciable loss of antileukemic activity. In this report, we review pre‐clinical evidence for synergistic antileukemic activity when nucleoside analog(s) and DNA‐alkylating agent(s) are combined in the most appropriate manner(s), without a measurable decrease in clinical efficacy compared with the more established alkylating agent combinations. Data from our own laboratory using combinations of fludarabine, clofarabine, and busulfan as prototype representatives for these respective classes of cytotoxic agents are combined with information from other investigators to explain how the observed molecular events will result in greatly enhanced synergistic cytotoxicity. We further present possible mechanistic pathways for such desirable cytotoxic synergism. Finally, we propose how this information‐backed hypothesis can be incorporated in the design of the next generation conditioning therapy programs in stem cell transplantation to optimize antileukemic efficacy while still safeguarding patient safety. Environ. Mol. Mutagen., 2010. © 2010 Wiley‐Liss, Inc.
Soil‐erosion models: where do we really stand?
Authors: Smith Roger E. , Quinton John , Goodrich David C , Nearing Mark
Published: June 2010

Wainwright et al. (2008a, b, c) propose a new model for simulating catchment‐scale erosion resulting from rainfall‐runoff events. In justification for such a new model, several existing process‐based models are criticized with regard to their theoretical underpinnings and presumptions. Since the authors do not correctly characterize the models mentioned, it is felt useful to correct the record in that regard, and to put the proposed model of Wainwright et al. in better perspective. The current models named in the criticism by Wainwright et al. include KINEROS (Woolhiser et al., 1990), KINEROS2 (Smith et al., 1995), EUROSEM (Morgan et al., 1998; Smith et al., 1995), and WEPP (Ascough et al., 1997). We refer to these below as the ‘critiqued models.’ The writers' familiarity with those models and their assumptions provide justification for the clarifications presented below. We note here that some of the models critiqued have had developments added, and published, since their initial release.

Wainwright et al.'s complaints and misunderstandings regarding existing models appear in our reading to be summarised by the following statements:

Existing models assume all sediment travels in suspension, whereas it likely does not.

The description of sediment movement relies on an assumption based on steady‐state flow.

The models assume that sediment velocity is the same as water velocity.

The Yalin (1972) transport equation is criticized as inapplicable or misapplied [with the clear implication that existing models rely on it].

The models should not use settling velocity or are using it incorrectly (p. 817).

Below we address each of these points in detail. In each case the criticisms are ill‐founded or result from a misunderstanding of the conceptual robustness of current catchment erosion dynamic models. Being familiar with the ‘critiqued’ models, we point out what we feel to be the true weaknesses of erosion models, for which the MAHLERAN model, developed by Wainwright et al., offers no cure. Their model suffers from many of the same weaknesses as those critiqued, plus some unique ones of its own. Copyright © 2010 John Wiley & Sons, Ltd.
Surface and sub‐surface Schmidt hammer rebound value variation for a granite outcrop
Authors: Černá Barbora , Engel Zbyněk
Published: June 2010

This study presents rock strength variations at granite outcrops and in subsurface vertical profiles in the Jizerské hory Mountains, Czech Republic. Schmidt hammer rebound values in subsurface profiles change gradually from the bedrock surface downward. An exponential relation has been observed between the R‐values and depth in rock outcrops to a depth of around 4·5 m. The exponential nature of the curve indicates that rock hardness increases more rapidly with depth in the uppermost 1?m section of the rock profile. A detailed study of rebound values obtained from both intact and polished rock exposures reveal effects of surface grinding on results of the Schmidt hammer method. The range of data collected increases after grinding, allowing more precise discrimination of rock surfaces in respect of age and weathering. The Schmidt hammer method may be used effectively as a relative‐age dating tool for rock surfaces that originated during the Late Pleistocene. It is concluded that this time limitation can be significantly mitigated by surface grinding before measurement. Copyright © 2010 John Wiley & Sons, Ltd.
Focal cerebral ischemia induces a multilineage cytogenic response from adult subventricular zone that is predominantly gliogenic
Authors: Li Lu , Harms Kate M. , Ventura P. Britten , Lagace Diane C. , Eisch Amelia J. , Cunningham Lee Anna
Published: June 2010

The purpose of this study was to ascertain the relative contribution of neural stem/progenitor cells (NSPCs) of the subventricular zone (SVZ) to lineages that repopulate the injured striatum following focal ischemia. We utilized a tamoxifen‐inducible Cre/loxP system under control of the nestin promoter, which provides permanent YFP labeling of multipotent nestin+ SVZ‐NSPCs prior to ischemic injury and continued YFP expression in all subsequent progeny following stroke. YFP reporter expression was induced in adult male nestin‐CreERT2:R26R‐YFP mice by tamoxifen administration (180 mg kg−1, daily for 5 days). Fourteen days later, mice were subjected to 60‐min transient middle cerebral artery occlusion (MCAO) and sacrificed at 2 days, 2 weeks, or 6 weeks post‐MCAO for phenotypic fate mapping of YFP+ cells using lineage‐specific markers. Migration of YFP+ cells from SVZ into the injured striatal parenchyma was apparent at 2 and 6 weeks, but not 2 days, post‐MCAO. At 2 weeks post‐MCAO, the average percent distribution of YFP+ cells within the injured striatal parenchyma was as follows: 10% Dcx+ neuroblasts, 15–20% oligodendrocyte progenitors, 59% GFAP+ astrocytes, and only rare NeuN+ postmitotic neurons. A similar phenotypic distribution was observed at 6 weeks, except for an increased average percentage of YFP+ cells that expressed Dcx+ (20%) or NeuN (5%). YFP+ cells did not express endothelial markers, but displayed unique anatomical relationships with striatal vasculature. These results indicate that nestin+ NSPCs within the SVZ mount a multilineage response to stroke that includes a gliogenic component more predominant than previously appreciated. © 2010 Wiley‐Liss, Inc.
RIG‐I mediates nonsegmented negative‐sense RNA virus‐induced inflammatory immune responses of primary human astrocytes
Authors: Furr Samantha R. , Moerdyk‐Schauwecker Megan , Grdzelishvili Valery Z. , Marriott Ian
Published: June 2010

While astrocytes produce key inflammatory mediators following exposure to neurotropic nonsegmented negative‐sense RNA viruses such as rabies virus and measles virus, the mechanisms by which resident central nervous system (CNS) cells perceive such viral challenges have not been defined. Recently, several cytosolic DExD/H box RNA helicases including retinoic acid‐inducible gene I (RIG‐I) have been described that function as intracellular sensors of replicative RNA viruses. Here, we demonstrate that primary human astrocytes constitutively express RIG‐I and show that such expression is elevated following exposure to a model neurotropic RNA virus, vesicular stomatitis virus (VSV). Evidence for the functional nature of RIG‐I expression in these cells comes from the observation that this molecule associates with its downstream effector molecule, interferon promoter stimulator‐1, following VSV infection and from the finding that a specific ligand for RIG‐I elicits astrocyte immune responses. Importantly, RIG‐I knockdown significantly reduces inflammatory cytokine production by VSV‐infected astrocytes and inhibits the production of soluble neurotoxic mediators by these cells. These findings directly implicate RIG‐I in the initiation of inflammatory immune responses by human glial cells and provide a potential mechanism underlying the neuronal cell death associated with acute viral CNS infections. © 2010 Wiley‐Liss, Inc.
Morphine induces the release of CCL5 from astrocytes: Potential neuroprotective mechanism against the HIV protein gp120
Authors: Avdoshina Valeriya , Biggio Francesca , Palchik Guillermo , Campbell Lee A. , Mocchetti Italo
Published: June 2010

A number of human immunodeficiency virus type‐1 (HIV) positive subjects are also opiate abusers. These individuals are at high risk to develop neurological complications. However, little is still known about the molecular mechanism(s) linking opiates and HIV neurotoxicity. To learn more, we exposed rat neuronal/glial cultures prepared from different brain areas to opiate agonists and HIV envelope glycoproteins gp120IIIB or BaL. These strains bind to CXCR4 and CCR5 chemokine receptors, respectively, and promote neuronal death. Morphine did not synergize the toxic effect of gp120IIIB but inhibited the cytotoxic property of gp120BaL. This effect was blocked by naloxone and reproduced by the μ opioid receptor agonist DAMGO. To examine the potential mechanism(s) of neuroprotection, we determined the effect of morphine on the release of chemokines CCL5 and CXCL12 in neurons, astrocytes, and microglia cultures. CCL5 has been shown to prevent gp120BaL neurotoxicity while CXCL12 decreases neuronal survival. Morphine elicited a time‐dependent release of CCL5 but failed to affect the release of CXCL12. This effect was observed only in primary cultures of astrocytes. To examine the role of endogenous CCL5 in the neuroprotective activity of morphine, mixed cerebellar neurons/glial cells were immunoneutralized against CCL5 prior to morphine and gp120 treatment. In these cells the neuroprotective effect of opiate agonists was blocked. Our data suggest that morphine may exhibit a neuroprotective activity against M‐tropic gp120 through the release of CCL5 from astrocytes. © 2010 Wiley‐Liss, Inc.
In vivo observation of the locomotion of microglial cells in the retina
Authors: Paques Michel , Simonutti Manuel , Augustin Sébastien , Goupille Olivier , El Mathari Brahim , Sahel José‐Alain
Published: June 2010

Microglial cells (MCs) are active sensors and reactive phagocytes of neural tissues. They are known to migrate and accumulate in areas of neuronal damage. Thus, microglial locomotion is an essential feature of the inflammatory reaction in neural tissue. Yet, to our knowledge there has been no report of direct in vivo observation of the migration of MCs. Here, we show that intravitreally injected cyanine dyes (DiO, DiI, and indocyanine green) are sequestrated in MCs during several months, and subsequently in vivo images of these fluorescent MCs can be obtained by confocal scanning laser ophthalmoscopy. This enabled noninvasive, time‐lapse observation of the migrating behavior of MCs, both in the basal state and following laser damage. In the basal state, a slow, intermittent, random‐like locomotion was observed. Following focal laser damage, MCs promptly (i.e., within 1 h) initiated centripetal, convergent migration. MCs up to 400 μm away migrated into the scar at velocities up to 7 μm/min. This early phase of centripetal migration was followed by a more prolonged phase of nontargeted locomotion around and within injured sites during at least 24 h. Cyanine‐positive cells persisted within the scar during several weeks. To our knowledge, this is the first in vivo observation of the locomotion of individual MCs. Our results show that the locomotion of MCs is not limited to translocation to acutely damaged area, but may also be observed in the basal state and after completion of the recruitment of MCs into scars. © 2010 Wiley‐Liss, Inc.
Involvement of p300 in constitutive and HIV‐1 Tat‐activated expression of glial fibrillary acidic protein in astrocytes
Authors: Zou Wei , Wang Zhenyuan , Liu Ying , Fan Yan , Zhou Betty Y. , Yang X. Frank , He Johnny J.
Published: June 2010

HIV‐1 Tat protein is an important pathogenic factor in HIV‐1‐associated neurological diseases. One hallmark of HIV‐1 infection of the central nervous system (CNS) is astrocytosis, which is characterized by elevated glial fibrillary acidic protein (GFAP) expression in astrocytes. We have shown that Tat activates GFAP expression in astrocytes [Zhou et al., (2004) Mol Cell Neurosci 27:296–305] and that GFAP is an important regulator of Tat neurotoxicity [Zou et al., (2007) Am J Pathol 171:1293–1935]. However, the underlying mechanisms for Tat‐mediated GFAP up‐regulation are not understood. In this study, we reported concurrent up‐regulation of adenovirus E1a‐associated 300 kDa protein p300 and GFAP in Tat‐expressing human astroytoma cells and primary astrocytes. We showed that p300 was indeed induced by Tat expression and HIV‐1 infection and that the induction occurred at the transcriptional level through the cis‐acting elements of early growth response 1 (egr‐1) within its promoter. Using siRNA, we further showed that p300 regulated both constitutive and Tat‐mediated GFAP expression. Moreover, we showed that ectopic expression of p300 potentiated Tat transactivation activity and increased proliferation of HIV‐1‐infected astrocytes, but had little effect on HIV‐1 replication in these cells. Taken together, these results demonstrate for the first time that Tat is a positive regulator of p300 expression, which in turn regulates GFAP expression, and suggest that the Tat‐Egr‐1‐p300‐GFAP axis likely contributes to Tat neurotoxicity and predisposes astrocytes to be an HIV‐1 sanctuary in the CNS. © 2010 Wiley‐Liss, Inc.