bluuebunny/crossref_metadata_2025_split huggingface dataset:
Speculations on the pathogenesis of CHARGE syndrome
Authors: Williams Marc S. 
Published: January 2005

AbstractTo be seriously considered, a theory about the pathogenesis of a multiple congenital anomaly syndrome should meet three criteria: (1) it should explain all of the anomalies associated with the syndrome; (2) it should explain why certain anomalies are not associated with the syndrome; and (3) it should predict anomalies that could be associated with the syndrome, but have not yet been described. The theory must eventually pass the ultimate test, that is, molecular confirmation of the proposed mechanism. Several theories about the pathogenesis of CHARGE syndrome have been proposed, but none of these meet the three criteria stated above. In this study, the author proposes that CHARGE syndrome is due to a disruption of mesenchymal–epithelial interaction (epithelial includes ectoderm and endoderm). The theory is tested against the major, minor, and occasional anomalies that are used to make the clinical diagnosis of CHARGE syndrome. Review of the known embryology of the organs and tissues involved in CHARGE syndrome confirms that mesenchymal–epithelial interactions are necessary for proper formation of these organs and tissues. The presence of limb anomalies in approximately one‐third of CHARGE syndrome patients fulfills criteria #3 above, in that limb anomalies were not felt to be a part of CHARGE syndrome until relatively recently. It is known that some patients with chromosomal abnormalities have a phenotype that overlaps with CHARGE syndrome. Given that critical developmental pathways must be robust and redundant in order to minimize errors, it may be that disruption of more than one gene is necessary to generate the CHARGE phenotype, as has been proposed for the holoprosencephaly sequence. Mutations and deletions of CHD7 have recently been identified as causing CHARGE syndrome in more than 50% of tested patients. Given this gene classes' putative role as a general controller of developmental gene expression as well as mesodermal patterning, it would fit the hypothesized mechanisms discussed in the study. © 2005 Wiley‐Liss, Inc.
Methylation: Its role in the environmental mobility of heavy elements
Authors: Thayer John S 
Published: January 2005

AbstractFormation of bonds between methyl groups and heavy elements (metals or metalloids) alters various physical properties such as solubility or volatility. This alteration enhances the mobility of the heavy metal and can play a major role in the environmental cycles for these elements. Environmental methylation has been established as a major factor in the environmental movement of mercury and arsenic, and very probably affects other elements similarly. Two methylating agents (methylcobalamin and methyl iodide) have been found to mobilize metals out of water‐insoluble compounds and/or anoxic sediments. These two compounds react with quite different substrates, but the kinetics of the resulting dissolutions follow virtually identical patterns. These reactions proceed through formation of a methylated intermediate on the substrate surface, followed by movement of the heavy element out of the solid lattice into the surrounding solution.
Model studies of trialkyltin–protein interactions: 13C NMR analysis of solution equilibria of the complex between trimethyltin and methyl N‐benzoyl‐l‐leucyl‐l‐histidinate
Authors: Harrison Philip G , Sharpe Nelson W 
Published: January 2005

Abstract13C NMR spectra for the 1:1 complex between methyl N‐benzoyl‐l‐leucyl‐l‐histidinate and the trimethyltin moiety in d‐chloroform (CDC13), d4‐methanol (CD3OD) dimethyl sulphoxide (DMSO) and d6‐DMSO/H2O solvents are reported, and contrasted with those for the free ligand. The spectra are interpreted in terms of a variety of solution equilibria illustrating the nature of the interaction between the trimethyltin species and primarily the imidazole ring of the histidine residue. Evidence for the preferential stability of pentacoordinate solution structures about tin is presented.
An international intercalibration for methylmercury in biological tissue
Authors: Thibaud Y. , Cossa D. 
Published: January 2005

AbstractAn intercalibration exercise between 13 laboratories from seven countries was conducted for comparing the methylmercury measurement techniques for marine biological tissues. Analyses have been conducted on two sets of samples: a fish muscle and a mussel soft tissue. Most of the participating laboratories performed six replicate analyses, allowing statistical comparisons. Various analytical techniques have been used, including cold vapour atomic absorption spectrophotometry (CVAA), electron capture gas liquid chromatography (GCEC), neutron activation (NAA), and inductively coupled plasma–isotopic dilution mass spectrometry (ICPIDMS). All of these methods offer similar results. They allow us to define consensus values which seem good estimates of the real concentrations. In addition the results show, for most of the participating laboratories, good accuracy and precision in the determination.
A comparative study on acute toxicity of methylarsonic acid, dimethylarsinic acid and trimethylarsine oxide in mice
Authors: Kaise Toshikazu , Yamauchi Hiroshi , Horiguchi Yoshiya , Tani Takayuki , Watanabe Shigenobu , Hirayama Teruhisa , Fukui Shozo 
Published: January 2005

AbstractThe acute toxicity of methylarsonic acid, CH3AsO(OH)2 (MAA), dimethylarsininc acid, (CH3)2AsO(OH) (DMAA), and trimethylarsine oxide, (CH3)3AsO (TMAO), were examined in mice with oral administration.The LD50 values of MAA, DMAA and TMAO were 1.8, 1.2 and 10.6 g kg−1 respectively. The toxicity of MAA and DMAA was very much lower than that for inorganic arsenic compounds. It was shown that TMAO has a similar acute toxicity to arsenobetaine. On the other hand, when the mice were administered 14.4 g kg−1 of TMAO once only orally, a garlic‐like odor (trimethylarsine, (CH3)3As) was definitely detectable in the exhalation of the animals by the human olfactory sense within about a few minutes.
Changes in fungal and bacterial populations in soil treated with two triorganotin(IV) compounds
Authors: Kuthubutheen A J , Wickneswari R , Kumar Das V G 
Published: January 2005

AbstractThe effects of two triorganotin(IV) compounds, diphenylbutyltin bromide (Ph2BuSnBr) and triphenyltin chloride·triphenylphosphine oxide (Ph3SnCl·Ph3PO), on soil bacterial and fungal populations were compared with that of Thiram and the commercial triorganotin fungicide ‘Brestan’ (triphenyltin acetate, Ph3SnOAc). Soil fungal populations were reduced most by Thiram, then by Ph3SnCl·Ph3PO, Ph2BuSnBr and Ph3SnOAc, in that order. Following the application of the compounds, there was a marked increase in the bacterial population in soil, the increase being greatest with Thiram and least with Ph3SnCl·Ph3PO. The triorganotin(IV) compounds were less harmful to soil fungi than Thiram. In Thiram‐treated soil, recolonization was slower than in soil treated with the triorganotin(IV) compounds. More species of fungi were tolerant to and persisted after application of the triorganotin(IV) compounds compared with Thiram. Among the fungi that were tolerant to the triorganotin(IV) compounds were cellulolytic species such as Trichoderma.
The degradation of triphenyltin biocides in neoprene‐based elastomeric marine antifouling coatings: 119mSn Mössbauer and chemical speciation studies
Authors: Allen David W , Brooks John S , Bailey Stephen 
Published: January 2005

AbstractThe fate of a series of triphenyltin biocides on incorporation into neoprene elastomers has been studied by 119mSn Mössbauer spectroscopy, together with supporting chemical derivatization techniques. It is shown that triphenyltin compounds undergo drastic degradation on incorporation into neoprene, suffering cleavage of phenyl–tin bonds to give a mixture of products in which all stages of dephenylation are present, including stannic chloride. This degradation occurs not only in elastomers cured at 150°C, but also in room temperature solvent‐cast samples.
Organotin concentrations in the Rivers Bure and Yare, Norfolk Broads, England
Authors: Waite M E , Evans K E , Thain J E , Waldock M J 
Published: January 2005

AbstractButyltin concentrations have been measured at eight freshwater sites (rivers and lakes) in the Norfolk Broads, UK, during 1986 and 1987. Tributyltin (TBT) was found in water samples from seven of the sites. Wherever TBT was present, dibutyltin and (usually) monobutyltin occurred. Levels of TBT exceeded 100 ng dm−3 in open stretches of both the Rivers Bure and Yare in 1986 and 1987. The highest concentration of TBT recorded for Wroxham Broad (a shallow lake) was 898 ng dm−3. Values of up to 3.26 μg dm−3 were measured in water samples taken from a marina. A depth profile for Wroxham Broad showed TBT to be uniformly distributed throughout the shallow water column. The results are discussed in relation to toxicity of TBT to freshwater organisms. Laboratory measurements of the degradation of TBT in freshwater from a marina gave a half‐life of six days at 20°C in the light.
Determination of arsenic compounds by high‐pressure liquid chromatography–graphite furnace atomic absorption spectrometry and thermospray mass spectrometry
Authors: Cullen William R , Dodd Matthew 
Published: January 2005

AbstractBiologically important arsenic species such as arsenobetaine, arsenocholine iodide, tetramethylarsonium iodide, methylarsonic acid, and dimethylarsinic acid can be separated and quantitated by HPLC. The pH‐sensitive separations on a weak anion‐exchange column are described, as well as separations on a reverse‐phase column with the aid of tetrabutylammonium nitrate or heptanesulfonic acid as ion‐pairing agents. The thermospray mass spectra of these arsenicals in addition to those of sodium arsenate and an arsenosugar derivative are described. This technique is suitable for HPLC MS studies.
Complexes in polymers III: Addition reactions of trans‐Ir(PPh3)2(CO)Cl embedded in polystyrene with hydrogen, oxygen, sulfur dioxide, carbon monoxide and gaseous iodine and of (η‐C5H5)Ru(η4‐1,5‐cyclooctadiene)Cl in polystyrene with carbon monoxide
Authors: Shaver Alan , Gao Jian Ping , Butler Ian S 
Published: January 2005

AbstractThe addition rections of trans‐Ir(PPh3)2(CO)Cl embedded in films of polystyrene (PS) with hydrogen, oxygen, sulfur dioxide, carbon monoxide and gaseous iodine were monitored by infrared spectroscopy and found to be similar to those occurring in toluene. While the reaction with iodine was rapid at the surface of the film as determined by attenuated‐total‐reflectance infrared spectroscopy, the reaction was much slower in the body of the film, as shown by transmission infrared spectroscopy. No such difference was observed for oxygen. The complex CpRu(COD)Cl (Cp = η‐C5H5, COD = 1,5‐cyclooctadiene) in PS readily undergoes ligand substitution by carbon monoxide (CO and 13CO) to give CpRu(CO)2Cl and CpRu(13CO)2Cl embedded in PS, respectively.
Organotin biocides XV: Modelling the interactions of triorganotins with cell membranes
Authors: Heywood B R , Molloy K C , Waterfield P C 
Published: January 2005

AbstractThe interaction of triorganotins with cell membranes has been examined using synthetic phospholipid membranes (vesicles). Electron microscopy and NMR methods indicate that the organotin is in a five‐coordinate environment at the membrane surface, and is associated weakly with the phosphate headgroups of the vesicle components. Both trimethyl‐ and tributyl‐tin cause extensive modifications to the vesicles including fusion, aggregation, blebbing and total rupture, these effects being initiated at concentrations as low as 25 μmol dm−3.
Carbon–oxygen bond cleavage in allylic esters promoted by low‐valent transition‐metal hydride complexes
Authors: Srivastava R S 
Published: January 2005

AbstractCoH(N2)(PPh3)3 promotes carbon–oxygen (CO) bond cleavage in allylic carboxylates to give the corresponding olefins at room temperature. On the other hand, RuH2(PPh3)4 and RhH(PPh3)4 are mainly active for CO bond cleavage at elevated temperature. Reaction proceeds through a mechanism involving predissociation of one of the tertiary phosphines from the RuH2(PPh3)4 and RhH(PPh3)4 and competitive coordination of allylic carboxylates and PPh3 to the vacant site on ruthenium and rhodium. A new six‐membered metallocyclic complex, Co(OCOCH2COCH3)(PPh3)2, has been isolated.
Synthesis and spectroscopic studies on organotin(IV) complexes of some pyrazoles and pyrazol‐5‐ones and their antibacterial activity
Authors: Al‐Allaf Talal A K , Al‐Bayati Redha H , Khalaf Subhi H 
Published: January 2005

AbstractA series of organotin(IV) complexes of the general formula RxSnCl4−x.L (where R=Me, n−Bu, Ph; x = 2 or 3; L = pyrazole or pyrazol‐5‐one) have been prepared and characterized by elemental analyses, IR and NMR spectroscopy. The ligands used were found to coordinate with R3SnCl species as monodentate ligands via the more reactive nitrogen atom, to give pentacoordinate tin complexes, whilst they may coordinate with R2SnCl2 species as bidentate ligands through the N–N linkage to give hexacoordinate tin complexes. These were demonstrated mainly by spectroscopic data. The tautomeric behaviour of organotin complexes of pyrazol‐5‐one ligands in inert (CDCl3) and donor (DMSO‐d6) solvents were also studied. The complexes were screened against six species of bacteria.
Reduction of clay surface‐sorbed organometallics during measurement of X‐ray photoelectron spectra (XPS)
Authors: Claire Ashcroft R. , Abid Khalid Y. , McWhinnie William R. , Saied Sayah O. 
Published: January 2005

AbstractSome organometallic compounds, e.g. Ph3SnCl, react on the surface of the smectite clay, laponite. Other compounds, e.g. Br3TeC6H4CH=NCH2CH2N=CHC6H4TeBr3, are sorbed onto the organophilic surface of cetylpyridinium‐ion‐exchanged Wyoming bentonite. X‐ray photoelectron spectroscopy (XPS) is an appropriate technique with which to examine the nature of the surface‐sorbed species; however, it is demonstrated that decomposition of the organometallic can occur when the clay surface is exposed over a period of time to energetic X‐rays. Thus, care must be taken with the interpretation of data of which some features may be the result of the XPS experiment.
Structure–Activity relationships of effect of aryltin compounds onCeratocystis ulmi
Authors: Eng George , Zhang Ying Zhi , Whalen Deborah , Ramsammy Roger , Khoo Lian Ee , Derosa Michael 
Published: January 2005

AbstractThe effect of aryltin compounds (Ar4Sn and Ar3SnCl) on the growth ofCeratocystis ulmi, the causative agent of Dutch elm disease, was studied in shake culture. In all cases, the triaryltins were more effective than the tetra‐aryltins as inhibitors ofC. ulmi in vitro.Furthermore, substitution on the phenyl ring at themeta‐ andpara‐ positions in the triaryltins did not have a major effect on the biocidal activity for the substituted triaryltins. Quantitative structure–activity relationships (QSARs) gave support to the idea that the species responsible for the inhibition of the fungus is the triaryltin cation. The QSARs further suggest that the interaction of the triaryltin cation with the fungal cell wall ofC. ulmiis by a non‐specific mechanism.
Application of whole cell NMR techniques to study the interaction of arsenic compounds with catharanthus roseus cell suspension cultures
Authors: Cullen William R. , Hettipathirana Deepthi I. 
Published: January 2005

Abstract1H spin–echo NMR spectroscopy of intact cells of C. roseus facilitates monitoring changes inside the cells on treatment with arsenicals. This in situ detection method is non‐invasive and non‐destructive in comparison to other available biochemical methods. Short term uptake of the arsinicals, methylarsinate MMA and dimethylarsenate DMA, by C. roseus cells that have reached stationary phase in 1‐B5 medium, is followed by using NMR spectroscopy, and in particular, the Carr–Purcell–Meiboom–Gill pulse sequence. An increase in the peak height of the methylarsenic resonance over a period of 11 h is indicative of uptake of each arsenical. However, there is no evidence of any biotransformation products in the 1H NMR spectra. The accumulation site of DMA is probably the vacuole as is seen from the change in the chemical shift of DMA as it moves into a compartment of lower pH. Biochemical changes associated with the presence of arsenicals are evident in the 1H NMR spectra of C. roseus cells isolated at different stages in the growth cycle. Although uptake has been demonstrated by other analytical techniques, the resonances corresponding to both MMA and DMA are not observed in the 1H NMR spectra of cells growing in media containing each arsenical. The association of these arsenicals with large biomolecules in the cell may account for these absences. In this event, the spins–spin relaxation time of the arsenic species would shorten and the signals would not be seen in the spin–echo NMR spectrum. In cells growing in the presence of MMA, a new resonance is observed at a chemical shift position 2.2 ppm after 15 days of growth. The shift in position of the resonance, from 1.75 ppm expected at physiological pH, may indicate an altered environment around the arsenic species such as high intracellular acidity.
The anti‐inflammatory activity of metal complexes and salts of amine carboxyboranes
Authors: Hall Iris H. , Rajendran K. G. , Chen S. Y. , Norwood V. N. , Morse K. W. , Sood A. , Spielvogel B. F. 
Published: January 2005

AbstractThe metal complexes and salts of amine carboxyboranes were shown to be potent anti‐inflammatory agents in rodents at 8 mg kg−1. They were effective in blocking induced edema, pleurisy and endotoxic shock while blocking both local and central pain processes. The ability of the agents to function as anti‐inflammatory agents is multi‐fold. First, lysosomal enzymes of specific cells, e.g. macrophages, were inhibited with IC50 values in the range of 10−6 M. Collagenase I and II activities were inhibited with IC50 values approximately equal to 10−4 M. The anti‐inflammatory activity of these agents at the molecular levels appears to be due to inhibition of the release of TNFα and Il‐1 from macrophages which indirectly control chemotaxic migration of white blood cells as indicated by the suppression of PMN and macrophage invasion into sponges implanted subcutaneously (SC) in mice. Furthermore, in these invading cells, the agents' blockage of TNFα and Il‐1 or Il‐2 release down‐regulates prostaglandin and leukotriene enzymatic synthetic rates and, consequently, their release, resulting in a reduction of the inflammation process.
From crystalline boryl‐substituted and boryl‐coupled 2,2,4,4,6,6‐hexamethyl‐cyclotrisilazanes to β‐SiC and BN
Authors: Schaible Sabine , Riedel Ralf , Boese R. , Werner E. , Klingebiel Uwe , Nieger Martin 
Published: January 2005

Abstract[Me2SiNBFN(SiMe3)2]3 (1) is synthesized in the reaction of trilithiated hexamethylcyclotrisilazane with F2BN(SiMe3)2. The mono‐ and dilithium derivatives of the six‐membered ring (Me2SiNH)2 Me2SiNSiFMe2 react with the F2B‐substituted cyclotrisilazane F2B(NSiMe2)3(SiFMe2)2 in the molar ratio 1:1 or 1:2 to give the BF‐coupled rings 2 and 3. The crystal structure analysis of 1 and 3 and pyrolysis of 1 and 3 with formation of silicon boron carbonitride and its crystallisation to composite powders at very high temperatures are reported.
In‐vitro prenatal toxicity of trimethylarsine, trimethylarsine oxide and trimethylarsine sulfide
Authors: Rick Irvin T. , Irgolic Kurt J. 
Published: January 2005

AbstractThe embryolethality and the embryotoxicity of trimethylarsine, trimethylarsine oxide and trimethylarsine sulfide were investigated employing Sprague–Dawley rat embryos with intact yolk sacs. The embryos were removed on day 11 of gestation and grown in a culture medium (Way‐mouth's 725/1) spiked with the arsenic compounds to concentrations in the range 4–100 mM in the presence or absence of rat liver (S‐9) homogenate. After 24 h the yolk‐sac circulation and heart beat were monitored (indicator of embryolethality), the crown‐to‐rump lengths were measured, the neural structures (somites) counted, and the development of the limb buds evaluated (indicators of embryotoxicity). At a trimethylarsine concentration of 18.7 mM 78% of the embryos were dead when no S‐9 was present. In the presence of S‐9 all embryos survived but were necrotic and malformed. Signs of embryotoxicity were observed at concentrations of 18.7 and 9.3 mM. At the 4.7 mM concentration the embryos grew as well as the control embryos. Trimethylarsine oxide v as lethal at 100 mM and severely embryotoxic at 50 and 25 mM. At all but the lowest concentration (4.5 mM) the embryos looked sick, and were frequently necrotic, deformed and underdeveloped. Trimethylarsine sulfide exhibited severe embryotoxicity at 50 mM concentration in the absence and in the presence of S‐9. Signs of acute toxicity were observable at 9 mM concentrations of trimethylarsine and trimethylarsine oxide. Compared with other environmental toxicants that show effects at concentrations orders of magnitude smaller, these arsenic compounds cannot be classified as very toxic.
A palladium(O)–samarium(II) system for the preparation of allenes from propargylic acetates: Application to the synthesis of 2,3‐naphthoquinodimethanes
Authors: Sugimoto Yuichi , Hanamoto Takeshi , Inanaga Junji 
Published: January 2005

AbstractThe selective conversion of 1,2‐bis(1′‐acetoxy‐2′‐ propynyl)benzene derivatives to the corresponding 1,2‐diallenylbenzenes with the aid of a palladium(O)–samarium(II) reduction system leads to a new route to fairly reactive o‐naphthoquinodimethane derivatives under mild conditions. The reactions of these naphthoquinodimethanes were found to follow different paths depending on the nature of the substituents on the terminal acetylenic carbon atoms. They undergo intermolecular Diels–Alder reactions with various dienophiles, intramolecular [2+2] cycloadditions, or intramolecular [1,5]‐sigmatropic hydrogen shifts.
Lanthanoid‐Metal‐Mediated organic reactions of acyltrialkylsilanes
Authors: Taniguchi Yuki , Fujii Nobuto , Takaki Ken , Fujiwara Yuzo 
Published: January 2005

AbstractAromatic acylsilanes such as benzoyltrimethylsilane react with ytterbium (Yb) metal to give the corresponding Yb‐oxametallacycle of the aromatic acylsilane. The Yb‐oxametallacycle thereby formed reacts with another aroylsilane to afford the symmetrical 1,2‐diarylacetylene in good yield. These nucleophilic Yb‐oxametallacycles have been found to react with a variety of electrophiles affording α‐silyl alcohol derivatives. In contrast, aliphatic acylsilanes are reduced with lanthanoid reagents such as Yb metal and samarium(II) iodide (SmI2) to give α‐silyl alcohols, and the corresponding aliphatic acetylene was not obtained.
Cerium in organic reactions: Construction of 2‐isoxazoline ring mediated by ammonium cerium nitrate
Authors: Sugiyama Takashi 
Published: January 2005

AbstractDirect construction of the 2‐isoxazoline ring directly from an alkene, or from an alkene and primary nitroalkane, was achieved in the presence of ammonium cerium nitrates. It has been found that (1) a carboxylic acid such as formic acid is required to promote the reaction, (2) an appropriate additive is required, when ammonium cerium(IV) nitrate is employed, but the additive is not necessary when ammonium cerium(III) nitrate is employed, (3) both ammonium cerium nitrates are converted into cerium(III) formate before the reaction takes place, and, (4) the cerium ion acts as a carrier of NOx as well as the activator of the nitro compound, and nitrate anion is the source of the NOx as well as the promoter of the reaction. A plausible reaction scheme has been proposed.