bluuebunny/crossref_metadata_2025 huggingface dataset:
Morphogenesis duringXenopusgastrulation requires Wee1-mediated inhibition of cell proliferation
Authors: Murakami Monica S. , Moody Sally A. , Daar Ira O. , Morrison Deborah K.
Published: January 2004

Major developmental events in early Xenopus embryogenesis coincide with changes in the length and composition of the cell cycle. These changes are mediated in part through the regulation of CyclinB/Cdc2 and they occur at the first mitotic cell cycle, the mid-blastula transition (MBT) and at gastrulation. In this report, we investigate the contribution of maternal Wee1, a kinase inhibitor of CyclinB/Cdc2, to these crucial developmental transitions. By depleting Wee1 protein levels using antisense morpholino oligonucleotides, we show that Wee1 regulates M-phase entry and Cdc2 tyrosine phosphorylation in early gastrula embryos. Moreover, we find that Wee1 is required for key morphogenetic movements involved in gastrulation, but is not needed for the induction of zygotic transcription. In addition, Wee1 is positively regulated by tyrosine autophosphorylation in early gastrula embryos and this upregulation of Wee1 activity is required for normal gastrulation. We also show that overexpression of Cdc25C, a phosphatase that activates the CyclinB/Cdc2 complex, induces gastrulation defects that can be rescued by Wee1, providing additional evidence that cell cycle inhibition is crucial for the gastrulation process. Together, these findings further elucidate the developmental function of Wee1 and demonstrate the importance of cell cycle regulation in vertebrate morphogenesis.
Murine tenascin-W: a novel mammalian tenascin expressed in kidney and at sites of bone and smooth muscle development
Authors: Scherberich A. , Tucker R. P. , Samandari E. , Brown-Luedi M. , Martin D. , Chiquet-Ehrismann R.
Published: January 2004

We cloned and characterized a novel member of the tenascin family of extracellular matrix proteins - the murine orthologue of zebrafish tenascin-W. Full-length recombinant tenascin-W was expressed and purified from mammalian cell cultures. Rotary shadowing followed by electron microscopy showed that tenascin-W forms hexabrachions. We studied its expression during development and in the adult by immunohistochemistry, in situ hybridization and immunoblotting. Tenascin-W is expressed during palate formation, osteogenesis and smooth muscle development. In the adult, tenascin-W is found in the kidney, cardiac semilunar valves, corneal limbus and periosteum. Tenascin-W and tenascin-C expression overlap in many of these areas. Bone-morphogenic-protein-2 treated C2C12 cells secrete tenascin-W and are able to adhere to and to extend actin-rich processes on a tenascin-W substratum. In vitro, cells bind to tenascin-W in an RGD-dependent manner. This adhesion is increased by transfection of α8 integrin, which localizes with tenascin-W in the periosteum and kidney.
The tyrosine phosphatase DEP-1 induces cytoskeletal rearrangements, aberrant cell-substratum interactions and a reduction in cell proliferation
Authors: Kellie Stuart , Craggs Graham , Bird Ian N. , Jones Gareth E.
Published: January 2004

The receptor protein tyrosine phosphatase density-enhanced phosphatase-1 (DEP-1) has been implicated in aberrant cancer cell growth and immune cell function, however, its function within cells has yet to be properly elucidated. To investigate the cellular function of DEP-1, stable cell lines inducibly expressing DEP-1 were generated. Induction of DEP-1 expression was found to decrease PDGF-stimulated tyrosine phosphorylation of a number of cellular proteins including the PDGF receptor, and to inhibit growth factor-stimulated phosphorylation of components of the MAPK pathway, indicating that DEP-1 antagonised PDGF receptor signalling. This was supported by data showing that DEP-1 expression resulted in a reduction in cell proliferation. DEP-1-expressing cells had fewer actin-containing microfilament bundles, reduced vinculin and paxillin-containing adhesion plaques, and were defective in interactions with fibronectin. Defective cell-substratum adhesion correlated with lack of activation of FAK in DEP-1-expressing cells. Time-lapse interference reflection microscopy of live cells revealed that although small focal contacts at the leading edge were generated in DEP-1-expressing cells, they failed to mature into stable focal adhesions, as found in control cells. Further motility analysis revealed that DEP-1-expressing cells retained limited random motility, but showed no chemotaxis towards a gradient of PDGF. In addition, cell-cell contacts were disrupted, with a change in the localisation of cadherin from discrete areas of cell-cell contact to large areas of membrane interaction, and there was a parallel redistribution of β-catenin. These results demonstrate that DEP-1 is a negative regulator of cell proliferation, cell-substratum contacts, motility and chemotaxis in fibroblasts.
Swm1p subunit of the APC/cyclosome is required for activation of the daughter-specific gene expression program mediated by Ace2p during growth at high temperature inSaccharomyces cerevisiae
Authors: Ufano Sandra , Pablo M. Evangelina , Calzada Arturo , del Rey Francisco , Vázquez de Aldana Carlos R.
Published: January 2004

SWM1 was originally identified for its role in the late steps of the sporulation process, being required for spore wall assembly. This protein, recently identified as one of the core subunits of the anaphase-promoting complex (APC) is also required to complete cell separation in vegetative cells during growth at high temperature. Mutants lacking SWM1 show a thermosensitive growth defect that is suppressed by osmotic support in the culture medium. At the restrictive temperature, swm1 mutants are unable to complete separation, forming chains of cells that remain associated and, with prolonged incubation times, the stability of the cell wall is compromised, resulting in cell lysis. This separation defect is due to a reduction in expression of CTS1 (the gene encoding chitinase) and a group of genes involved in cell separation (such as ENG1,SCW11, DSE1 and DSE2). Interestingly, these genes are specifically regulated by the transcription factor Ace2p, suggesting that Swm1p is required for normal expression of Ace2p-dependent genes during growth at high temperatures. Although no defect in Ace2p localization can be observed at 28°C, this transcription factor is unable to enter the nucleus of the daughter cell during growth at 38°C. Under these growth conditions, swm1 cells undergo a delay in exit from mitosis, as determined by analysis of Clb2p degradation and Cdc28p-Clb2p kinase assays, and this could be the reason for the cytoplasmic localization of Ace2p.
Trafficking of β2-adrenergic receptors: insulin and β-agonists regulate internalization by distinct cytoskeletal pathways
Authors: Shumay Elena , Gavi Shai , Wang Hsien-yu , Malbon Craig C.
Published: January 2004

Insulin and β-adrenergic agonists stimulate a rapid phosphorylation and sequestration of the β2-adrenergic receptors (β2ARs). Although the expectation was that a common pathway would be involved in the trafficking of the β2AR in response to either hormone, studies reported herein show the existence of unique cytoskeletal requirements for internalization/recycling of G-protein-coupled receptors, such as the β2AR. Treatment of human epidermoid carcinoma A431 cells with nocodazole, which binds tubulin monomer in vivo and catalyzes the depolymerization of microtubules, effectively blocks β-adrenergic agonist-induced, but not insulin-induced, sequestration of β2ARs. Treatment with latrunculin-A, an agent that sequesters actin monomer and leads to loss of actin filaments, had no effect on the ability of β-adrenergic agonists to stimulate internalization of β2ARs, but blocked the ability of insulin to stimulate counterregulation of β2ARs via internalization. Although nocodazole had no effect on insulin-stimulated sequestration of β2ARs, the recycling of the internalized receptors to the cell membrane was sensitive to depolymerization of microtubules by this agent. Latrunculin-A, by contrast, blocks the recycling of β2ARs internalized in response to β-agonist, while attenuating recycling of receptors internalized in response to insulin stimulation. These data show the existence of unique cytoskeletal requirements for G-protein-coupled-receptor trafficking in response to agonist compared with a counterregulatory hormone, and for sequestration versus recycling of the receptors to the cell membrane.
A role for the spectrin superfamily member Syne-1 and kinesin II in cytokinesis
Authors: Fan Jun , Beck Kenneth A.
Published: January 2004

Expression of a dominant negative fragment of the spectrin family member Syne-1 causes an accumulation of binucleate cells, suggesting a role for this protein in cytokinesis. An association of this fragment with the C-terminal tail domain of the kinesin II subunit KIF3B was identified by yeast two-hybrid and co-precipitation assays, suggesting that the role of Syne-1 in cytokinesis involves an interaction with kinesin II. In support of this we found that (1) expression of KIF3B tail domain also gives rise to multinucleate cells, (2) both Syne-1 and KIF3B localize to the central spindle and midbody during cytokinesis in a detergent resistant and ATP sensitive manner and (3) Syne-1 localization is blocked by expression of KIF3B tail. Also, membrane vesicles containing syntaxin associate with the spindle midbody with identical properties. We conclude that Syne-1 and KIF3B function together in cytokinesis by facilitating the accumulation of membrane vesicles at the spindle midbody.
Mechanism of recruiting Sec6/8 (exocyst) complex to the apical junctional complex during polarization of epithelial cells
Authors: Yeaman Charles , Grindstaff Kent K. , Nelson W. James
Published: January 2004

Sec6/8 (exocyst) complex regulates vesicle delivery and polarized membrane growth in a variety of cells, but mechanisms regulating Sec6/8 localization are unknown. In epithelial cells, Sec6/8 complex is recruited to cell-cell contacts with a mixture of junctional proteins, but then sorts out to the apex of the lateral membrane with components of tight junction and nectin complexes. Sec6/8 complex fractionates in a high molecular mass complex with tight junction proteins and a portion of E-cadherin, and co-immunoprecipitates with cell surface-labeled E-cadherin and nectin-2α. Recruitment of Sec6/8 complex to cell-cell contacts can be achieved in fibroblasts when E-cadherin and nectin-2α are co-expressed. These results support a model in which localized recruitment of Sec6/8 complex to the plasma membrane by specific cell-cell adhesion complexes defines a site for vesicle delivery and polarized membrane growth during development of epithelial cell polarity.
Gene switching inAmoeba proteuscaused by endosymbiotic bacteria
Authors: Jeon Taeck J. , Jeon Kwang W.
Published: January 2004

The expression of genes for S-adenosylmethionine synthetase (SAMS), which catalyzes the synthesis of S-adenosylmethionine (AdoMet), a major methyl donor in cells, was studied in symbiont-free (D) and symbiont-bearing (xD) amoeba strains to determine the effect of bacterial endosymbionts. The symbionts suppressed the expression of the gene in host xD amoebae, but amoebae still exhibited about half the enzyme activity found in symbiont-free D amoebae. The study was aimed at elucidating mechanisms of the suppression of the amoeba's gene and determining the alternative source for the gene product. Unexpectedly, we found a second sams (sams2) gene in amoebae, which encoded 390 amino acids. Results of experiments measuring SAMS activities and amounts of AdoMet in D and xD amoebae showed that the half SAMS activity found in xD amoebae came from the amoeba's SAMS2 and not from their endosymbionts. The expression of amoeba sams genes was switched from sams1 to sams2 as a result of infection with X-bacteria, raising the possibility that the switch in the expression of sams genes by bacteria plays a role in the development of symbiosis and the host-pathogen interactions. This is the first report showing such a switch in the expression of host sams genes by infecting bacteria.
On the Reaction Mechanism of “Higher-Order Cuprate”, Alias “Lipshutz Cuprate”
Authors: Nakamura Eiichi , Yoshikai Naohiko
Published: January 2004

An organocuprate reagent of the R2Cu(CN)Li composition introduced by Lipshutz has been frequently used in organic synthesis because its reactivity in some reactions is higher than that of the standard Gilman reagent R2CuLi. The higher reactivity of the Lipshutz cuprate was once ascribed to a dianionic tri-coordinated copper(I) (“higher-order”) structure, but numerous structural studies over the last ten years have shown that the Lipshutz cuprate exists as a “cyano-Gilman” (R2CuLi·LiCN) cuprate. This conclusion notwithstanding, our recent theoretical study indicated that a minor and undetectable species such as R(CN)CuLi·LiR may play some roles in the substitution and the addition reactions of the Lipshutz cuprate. The high reactivity of the minor species originates from the anisotropic and multi-coordination capability of the cyanide ligand to metals. Our result accounts for the higher or anomalous reactivity of the Lipsthuz cuprate in some reactions, and further demonstrates the importance of computational study on poly-metallic reaction pathways, where experimental mechanistic information may be difficult to obtain.
Surface Tension of Barium Chlorapatite Crystals Grown from Flux
Authors: Suzuki Takaomi , Nakayama Kazuhito , Oishi Shuji
Published: January 2004

Large, well-formed crystals of barium chlorapatite [Ba5Cl(PO4)3] were grown from a sodium chloride flux. The prismatic crystals of Ba5Cl(PO4)3 were bordered by {(101-0)} and {(101-1)} faces. The crystals have a tendency to elongate in the <0001> directions. Contact angles of water, formamid, ethylene glycol, and diethylene glycol droplets on the Ba5Cl(PO4)3 crystals were observed. The surface tension, that is, the surface free energy of the grown crystals, was calculated in order to study the relationship between the morphology and the surface tension of the crystal. The contact angles of water, formamid, ethylene glycol, and diethylene glycol droplets on the ((101-0) ) face of a Ba5Cl(PO4)3 crystal were 40°, 37°, 30°, and 26°, respectively, and the contact angles of those liquids on the ((101-1) ) face were 20°, 18°, 16°, and 14°, respectively. The surface tension of the crystal faces were calculated from the observed contact angles using harmonic mean and geometric mean equations. The calculated surface tensions of the crystal faces were 58 ± 1 and 69 ± 1 mN/m for the ((101-0) ) and ((101-1) ) faces of a Ba5Cl(PO4)3 crystal, respectively. The fact that the surface tension of the ((101-0) ) face is smaller than that of the ((101-1) ) face indicates that the ((101-0) ) face is more stable than the ((101-1) ) face. The energetic stability of the ((101-0) ) face corresponds to the morphology of the Ba5Cl(PO4)3 crystal, which elongates in the <0001> directions.
Density Functional Studies of [{Mo(η5-Cp)(CO)2}2(μ-H)(μ-PMe2)], [{Mo(η5-Cp)(CO)2}2(μ-PMe2)]− and [{Mo(η5-Cp)(CO)3}2]: Do the Metal–Metal Bonds Exist?
Authors: Hong Fung-E , Chang Yu-Chang
Published: January 2004

Computational methods employing the Kohn–Sham description of density functional theory with the hybrid B3LYP-DFT means were used to investigate the nature of the metal–metal interactions of [{Mo(η5-Cp)(CO)2}2(μ-H)(μ-PMe2)] 1 and its deprotonated form, [{Mo(η5-Cp)(CO)2}2(μ-PMe2)]−4 as well as a dimeric compound, [{Mo(η5-Cp)(CO)3}2] 3. Both the Boys localization procedures as well as NBO analysis were performed to probe the character of the localized orbitals for all the three compounds. Consequently, a direct molybdenum–molybdenum bond was found in compound 3 and 4. However, there is neither a direct metal–metal bond found in 1 at its singlet ground state nor any unpaired electron around each metal center.
Ammonia Absorption on Alkaline Earth Halides as Ammonia Separation and Storage Procedure
Authors: Liu Chun Yi , Aika Ken-ichi
Published: January 2004

For the low pressure ammonia synthesis (∼1 MPa, 573–623 K), 40–80 kPa of ammonia produced must be separated. For this purpose, the absorption behavior of five kinds of alkaline earth metal halides (MgCl2, CaCl2, CaBr2, SrCl2, and SrBr2) and their hydrated forms were studied under 0 to 80 kPa of ammonia at 298 to 473 K. Although the equilibrium data of the ammine complex formation of these materials are known, the absorption started at higher pressure than the equilibrium data, due to the presence of enough chemical potential Δμ for ammonia absorption. Initial absorption (to low numbers of coordinated ammonia) was slow and depended on the sample specific surface area. The successive absorption (beyond 1 or 2 of ammonia coordination) occurs easily and reversibly. The “quasi” absorption and desorption isotherms studied here were useful for the design of ammonia separation materials. MgCl(OH), CaCl2, and CaBr2 were found to be practical for TSA (Temperature Swing Absorption) material working between 298 and 473 K at 40 kPa. Especially, the ammonia separation capacity of MgCl(OH) (26.1 mmol g−1) was 5.5 times as high as that of Na exchanged Y-zeolite.
Rhodium-Catalyzed Asymmetric Addition of Organo-Boron and -Titanium Reagents to Electron-Deficient Olefins
Authors: Hayashi Tamio
Published: January 2004

Asymmetric 1,4-arylation and -alkenylation was achieved by use of organoboronic acids or their derivatives in the presence of a rhodium catalyst coordinated with binap or its related ligands. The scope of this asymmetric addition is very broad, α,β-unsaturated ketones, esters, amides, 1-alkenylphosphonates, and 1-nitroalkenes being efficiently converted into the corresponding 1,4-addition products with over 95% enantioselectivity. The catalytic cycle of the reaction in water is proposed to involve three intermediates (aryl- or alkenyl-rhodium, (oxa-π-allyl)rhodium, and hydroxo-rhodium), as suggested by NMR studies on the rhodium intermediates. The asymmetric addition of B-aryl-9BBN and ArTi(OPr-i)3 in aprotic solvents proceeded with high enantioselectivity under mild conditions to give the corresponding metal enolates as the 1,4-addition products.
Separation of Dissolved Aluminum in Neutral/Slightly Basic River Water by Cation-Exchange Chromatography with Fluorometric Detection of the Lumogallion–Aluminum Complex
Authors: Hara Hirokazu , Fujiwara Miyuki , Kamiyama Hiroko
Published: January 2004

The separation of dissolved aluminum in neutral/slightly basic river (Seta River) water was carried out using high-performance cation-exchange chromatography with a gradient elution of calcium ion in a dilute nitric acid solution (pH 4) and fluorometric detection of the lumogallion–aluminum complex. Although three peaks may appear, which correspond to species having a charge of less than +1, +2 and +3, only one major peak at the “3+” position appeared. From the sample pH and this result of separation, the main species of dissolved aluminum was concluded to be Al(OH)4−. In order to evaluate whether the elution was complete or not, the peak areas obtained with and without the cation-exchange column were compared. For an accurate evaluation of the elution peak, the residual solution of the solvent extraction with the 8-quinolinol/chloroform system was used. The elution of dissolved aluminum from the cation-exchange column was found to be incomplete (or not quantitative); i.e., the percentage of eluted aluminum was 79 and 70% for two Seta River water samples in October and January, respectively. The chemical form of the aluminum species which was adsorbed in the cation-exchange column is discussed.
Intermolecular Phenyl Ligand Transfer of Pt(II) and Pd(II) Complexes with Bidentate Ligand
Authors: Suzaki Yuji , Osakada Kohtaro
Published: January 2004

[PtPh2(dppe)] (dppe = 1,2-bis(diphenylphosphino)ethane) reacts with equimolar [PtCl2(cod)] (cod = 1,5-cyclooctadiene) to give a mixture of [PtPh2(cod)] (38%), [PtCl(Ph)(cod)] (53%) and [PtCl2(dppe)] (72%) via exchange of the phenyl and chloro ligands among the Pt complexes. The reaction is strongly inhibited by addition of Cl−. The intermolecular phenyl ligand transfer from Pd to Pt is observed in the reaction of [PdCl(Ph)(bpy)] (bpy = 2,2′-bipyridine) with [PtX2(cod)] (X = Cl, I), which produces [PtX(Ph)(cod)]. The reaction of [PdCl(Ph)(bpy)] with [PdCl2(cod)], giving [Pd2(μ-Cl)2{(4,5-η-κC1)-(C8H12Ph)}2], occurs much faster than a similar reaction of [PdCl(Ph)(bpy)] with [PtCl2(cod)]. [PtPh2(L2)] (L2 = cod, dppe) reacts with [PdCl2(cod)] in CH2Cl2 at room temperature to afford [Pd2(μ-Cl)2{(4,5-η-κC1)-(C8H12Ph)}2] via intermolecular phenyl ligand transfer from Pt to Pd and subsequent insertion of a C=C bond of cod into the Pd–Ph bond. Cationic Pd complexes [Pd(acetone)2(cod)]2+(BF4−)2 and [Pd(η3-C3H5)(acetone)2]+(BF4−) react with [PtPh2(cod)] to form biphenyl. All these results indicate that chloro complexes of Pd and Pt with cod ligand undergo the ligand exchange with the phenyl complexes of these metals.
Autocatalytic Nitration of Pyrene by Aerated Nitrogen Dioxide in Solution and Comparison with the Nitration on Silica Particles
Authors: Hasegawa Kiyoshi , Kaneko Hiroshi , Ogawa Tatsuya
Published: January 2004

The nitration mechanism of pyrene (PYH) by aerating NO2 in solution was studied by varying the factors (concentration of NO2, addition of HNO3 gas and H2O, 1-substituent on PYH, and solvent) affecting the nitration. Only 1-nitropyrene was formed. In acetonitrile, both the decrease in PYH and the increase in 1-nitropyrene depicted sigmoid curves, that is, their changes proceeded abruptly after an induction period, and finally approached to zero. The characteristic feature was reasonably explained by the facts that H+ dissociated from HNO3, accumulated by aerating NO2 into trace water-containing acetonitrile and released by the nitration, acted as an autocatalyst. The nitration proceeded electrophilically based on the 1-substituent effect of PYH, and accelerated with increasing polarity of the solvents. The nitration was studied kinetically and an ionic mechanism involving NO2+ as an electrophile was proposed. The nitration mechanism of PYH in acetonitrile was different from that in the adsorbed water on silica gel.
Synthesis of Allyl Acetals and Their Catalytic Claisen–Cope Rearrangement
Authors: Nakabayashi Kazuhiro , Ooho Masato , Niino Teppei , Kitamura Tsugio , Yamaji Teizo
Published: January 2004

We have synthesized various types of acetals using 3-methyl-3-butenal and 2-alkenyl, furfuryl, benzyl, p-substituted benzyl, and 2-pentynyl alcohols. These acetals have given corresponding aldehydes after an acid catalytic reaction. Trifluoroacetic acid (CF3COOH) was the best catalyst. The best yield attained was 79% when 3-methyl-3-butenal di(trans-2-pentenyl) acetal was used as a substrate. We also demonstrated that this reaction proceeded via a Claisen–Cope rearrangement.
A New Family of 2(3H)-Thiazolone Azines as Precursors to Air-Stable Radical Cations
Authors: Hammami Amer , Cavalié-Kosheiry Hicham , Armand Michel
Published: January 2004

A Novel 2(3H)-thiazolone azines family having RF substituents on the 4,4′-positions were efficiently prepared in good yield. The two-step synthesis involves the preparation of N,N′-dialkyl-1,2-hydrazinedicarbothioamides and their reaction with bromomethyl perflooroalkyl ketone, resulting in double ring closure. All the members prepared in this new family of compounds form stable radical cations, which enables them to be considered as ideal candidates for electrochemical tuning of light absorption as in electrochromic windows or displays and as redox indicators or mediators.
6-Nitro-2-benzothiazolyl α-Glucoside and α-Mannoside in β-Selective Glycosylations
Authors: Hashihayata Takashi , Mandai Hiroki , Mukaiyama Teruaki
Published: January 2004

Highly β-selective glucosylations of glycosyl acceptors having a primary hydroxy group with a 6-nitro-2-benzothiazolyl α-glucoside donor 3α proceeded smoothly in the presence of a catalytic amount of trifluoromethanesulfonic acid (TfOH) in CH2Cl2 at −78 °C to afford the corresponding glycosides in high yields. With the use of 3α, β-saccharides could be obtained more dominantly than other α-glucosyl donors such as thioform- and trichloroacet-imidates or fluoride in the glucosylation under the same conditions. Similarly, highly β-selective mannosylations of glycosyl acceptors with a 6-nitro-2-benzothiazolyl α-mannoside donor 18α were carried out smoothly in the presence of a catalytic amount of tetrakis(pentafluorophenyl)boric acid H[B(C6F5)4] to afford the corresponding disaccharides in good to high yields; 18α apparently behaved as a potent donor here for the construction of β-mannoside linkage. Interestingly, in situ anomerization from 18β to 18α was observed when β-mannosyl donor 18β was treated with a catalytic amount of H[B(C6F5)4] in CH2Cl2.
Synthesis of [2]- and [3]Rotaxanes by an End-Capping Approach Utilizing Urethane Formation
Authors: Furusho Yoshio , Sasabe Hisahiro , Natsui Daisuke , Murakawa Ken-ichi , Takata Toshikazu , Harada Toshiro
Published: January 2004

Several axle-shaped sec-ammonium salts having hydroxy groups at the terminal ends were allowed to react with 3,5-dimethylphenyl isocyanate in the presence of dibenzo-24-crown-8 ether (DB24C8) in CHCl3 by the catalysis of dibutyltin dilaurate to afford the corresponding [2]rotaxanes in good yields. Several Lewis acids other than dibutyltin dilaurate were effective for the end-capping. Although N,N-dimethylacetamide was not a suitable solvent, the use of chlorobenzene and nitromethane as solvents gave the [2]rotaxane in high yields. When a C2-chiral 26-membered crown ether, prepared from biphenyl-2,2′,6,6′-tetrol and l-tartaric acid, was employed instead of DB24C8, the corresponding optically active [2]rotaxane was isolated in 47% yield. The present method was successfully applied to the synthesis of [3]rotaxane by employing hexamethylene diisocyanate. Thus, end-capping by acid-catalyzed urethane formation from alcohol and isocyanate was demonstrated to be an effective protocol for the synthesis a variety of rotaxanes, based on the sec-ammonium salt/crown ether recognition motif.
Synthesis of 1,2,4-Trithiolanes from Thione S-Oxides and Lawesson Reagent at Room Temperature
Authors: Okuma Kentaro , Shigetomi Toshiyuki , Shibata Shinji , Shioji Kosei
Published: January 2004

The reaction of 2,2,4,4-tetramethyl-3-thioxocyclobutanone S-oxide with Lawesson reagent (L. R.) afforded the corresponding 1,2,4-trithiolane. Thiopivalophenone and thiopivalophenone S-oxides reacted with L. R. at rt to give the corresponding S-sulfide, which further reacted with thiones to afford the corresponding cis-1,2,4-trithiolanes.
pH Dependence of Interparticle Coupling for Gold Nanoparticle Assemblies Formation: Electrostatic Attraction and Hydrogen Bonding
Authors: Su Chia-Hao , Wu Pei-Lin , Yeh Chen-Sheng
Published: January 2004

With the addition of ω-sulfanylalkanoic or ω-alkyldisulfanylalkanoic acids to sodium-contained aqueous Au colloidal solutions, close-packed self-assembly occurred UV–vis, TEM, solid-state 13C NMR, and FT-IR spectra were employed to study the resulting aggregation arrays. The resulting two-dimensional Au assemblies exhibited interparticle coupling via both hydrogen bonding and electrostatic interactions at pH 6. Either acidic (pH 3) or base (pH 11) generated significant three-dimensional close-packed aggregates. It is suggested that electrostatic interactions might lead to the aggregates during the dry-up process in the preparation of TEM samples of the Au nanoparticles capped with COO− terminals at pH 11. For the acidic solutions (pH 3), coagulation was governed by hydrogen-bonding forces.
Time-Resolved Thermodynamic Properties of Intermediate Species during Photochemical Reactions
Authors: Terazima Masahide
Published: January 2004

Thermodynamics and kinetics are very large and important fields in science. However, experimental efforts to link these two fields have been very limited so far. For instance, although the themodynamical properties of transient species are essential for the knowledge of the nature and energetics of the reaction, such data have been very scarce. Kinetic study of a reaction from a view point of thermodynamic properties in the time domain should be very useful to detect a spectrally silent kinetic property. We have developed experimental methods to measure the time development of the thermodynamical properties of transient species without any assumption and without any temperature or pressure variations. Some of the results, in particular applications to reactions of biological proteins (photodissociation of the ligand of carboxymyoglobin, photo-reaction of Photoactive Yellow Protein (PYP) and octopus rhodopsin), are reviewed.
Recent Synthetic Advances of Tetrathiafulvalene-Based Organic Conductors
Authors: Otsubo Tetsuo , Takimiya Kazuo
Published: January 2004

The synthetic chemistry of tetrathiafulvalene (TTF)-type electron donors has been markedly promoted by introducing two key reactions, the one-pot preparation of 1,3-dichalcogenole-2-chalcogenones from terminal alkynes and the formation of heterocyclic rings via transalkylation on a chalcogen atom. In combination with a conventional trialkyl phosphite-promoted coupling reaction of 1,3-dichalcogenole-2-chalcogenones, the first reaction constitutes a ready access to the tetrachalcogenafulvalene skeleton. As a result, a number of previously inaccessible TTF-type electron donors were readily obtained. These included tetraselenafulvalene (TSF) derivatives, the selenium/sulfur or selenium/tellurium hybrid systems, dimeric TSFs linked with a single spacer group, and sophisticated stacked TSF phanes. The second reaction is very useful in constructing additional heterocyclic ring(s) on the tetrachalcogenafulvalene skeleton. A wide variety of five-, six-, and seven-membered heterocycle-fused TTF-type compounds were thus synthesized. These were systematically examined for superior electron donors of conductive molecular complexes. This study resulted in the discovery of two novel electron donors, methylenedithio-tetraselenafulvalene and methylenedithio-diselenadithiafulvalene, that form unique superconductors with exceptionally high conductivities at room temperature. The scopes and limitations of these synthetic reactions are described in connection with the recent research trends of TTF-based organic (super)conductors.
Dioxygen Reactivity of Copper(I) Complexes with Tetradentate Tripodal Ligands Having Aliphatic Nitrogen Donors: Synthesis, Structures, and Properties of Peroxo and Superoxo Complexes
Authors: Komiyama Kazuya , Furutachi Hideki , Nagatomo Shigenori , Hashimoto Akifumi , Hayashi Hideki , Fujinami Shuhei , Suzuki Masatatsu , Kitagawa Teizo
Published: January 2004

Oxygenation of copper(I) with tetradentate tripodal ligands (L) comprised of a tris(aminoethyl)amine (tren) skeleton having sterically bulky substituent(s) on the terminal nitrogens has been investigated, where L = tris(N-benzylaminoethyl)amine (LH,Bn), tris(N-benzyl-N-methylaminoethyl)amine (LMe,Bn), or tris(N,N-dimethylaminoethyl)amine (LMe,Me). All the copper(I) complexes reacted with dioxygen at low temperatures to produce superoxocopper(II) and/or trans-(μ-1,2-peroxo)-dicopper(II) complexes depending on the steric bulkiness of the terminal nitrogens and the reaction conditions. The reaction of a copper(I) complex [Cu(LH,Bn)]+ at −90 °C in acetone resulted in the formation of a superoxo complex [Cu(LH,Bn)(O2)]+ as a less stable species and a peroxo complex [{Cu(LH,Bn)}2(O2)]2+ as a stable species. The structures of [Cu(LH,Bn)]ClO4 and [{Cu(LH,Bn)}2(O2)](BPh4)2·8(CH3)2CO were determined by X-ray crystallography. [{Cu(LH,Bn)}2(O2)]2+ has a trans-(μ-1,2-peroxo)-dicopper(II) core with a trigonal bipyramidal structure. The O–O bond distance is 1.450(5) Å with an intermetallic Cu···Cu separation of 4.476(2) Å. The resonance Raman spectrum of [{Cu(LH,Bn)}2(O2)]2+ measured at −90 °C in acetone-d6 showed a broad ν(O–O) band at 837–834 cm−1 (788 cm−1 for an 18O labeled sample) and two ν(Cu–O) bands at 556 and 539 cm−1, suggesting the presence of two peroxo species in solution. [Cu(LMe,Bn)]+ also produced both superoxo and trans-μ-1,2-peroxo species, [Cu(LMe,Bn)(O2)]+ and [{Cu(LMe,Bn)}2(O2)]2+. At a lower concentration of [Cu(LMe,Bn)]+ (∼0.24 mM) and higher dioxygen concentration (P(O2) = ∼1 atm), the superoxo species is predominantly formed, whereas at a higher concentration of [Cu(LMe,Bn)]+ (∼1 mM) and lower dioxygen concentration (P(O2) = ∼0.02 atm) the formation of the peroxo species is observed. The resonance Raman spectrum of [Cu(LMe,Bn)(O2)]+ (∼1 mM) in acetone-d6 at ∼−95 °C exhibited a ν(O–O) band at 1120 cm−1 (1059 cm−1 for an 18O labeled sample) and that of [{Cu(LMe,Bn)}2(O2)]2+ (∼3 mM) in acetone-d6 at ∼−90 °C showed two ν(O–O) bands at 812 and 797 cm−1 (767 and 753 cm−1 for an 18O labeled sample), respectively. A similar observation was also made for [{Cu(LMe,Me)}2(O2)]2+. Relationships between the energies of the LMCT and d–d transitions and those of the ν(O–O) and ν(Cu–O) stretching vibrations and the steric constraints in the Cu(II)–(O22−)–Cu(II) core are discussed.
The Effect of NaClO4 Concentration on the Two-Step Electroreduction of Zn2+ Ions in the Presence of Tetramethylthiourea
Authors: Nieszporek Jolanta , Gugala Dorota , Sienko Dorota , Fekner Zygmunt , Saba Jadwiga
Published: January 2004

The dependence of the two-step reduction of Zn2+ ions on NaClO4 and TMTU concentration at the dropping mercury electrode was examined. The catalytic activity of TMTU is related to both electron transfer steps and decreases in the order: 1 M NaClO4 > 0.5 M NaClO4 > 0.1 M NaClO4. In each of the studied systems there was observed a much larger increase in the (kts2) values compared to the (kts1) values when the concentration of TMTU was increased. A linear relationship between the rate constant of the electroreduction of Zn2+ and the relative surface excess of TMTU indicates the formation of a bridge between Zn2+ and TMTU which facilitates the transfer of electrons across the inner layer.
Allergen immunotherapy in ENT: historical perspective
Authors: Kim D. S. , Drake-Lee A. B.
Published: January 2004

The origins of immunology and allergy are founded upon the early 19th century microbiological studies of Jenner and Pasteur. It was discovered that the immune system could cause harm. The subspecialty of allergy began with the coining of the term by Von Pirquet in 1906 to describe disorders resulting from hyper-reaction to normally innocuous environmental agents.

Understanding the scientific basis of the immune system and allergy allowed Noon and Freeman, and later Cooke, to develop allergen immunotherapy. Initially the technique was crude, but with the subsequent key discovery of IgE, more accurate methods of diagnosis (such as the radioallergosorbent test (RAST)) and treatment ensued. The efficacy of specific immunotherapy has been demonstrated by many double-blind trials culminating in the WHO position paper.

DNA recombinant technology has provided detailed molecular understanding of allergic disorders, which has resulted in several novel methods of immunotherapy that are potentially safer and more effective. Use of recombinant allergens, T-cell peptides, DNA vaccination with CpG motifs or plasmid vectors and anti-IgE strategies with monoclonal antibodies are showing promise.
Infection, allergy and the hygiene hypothesis: historical perspective
Authors: Kim D. S. , Drake-Lee A. B.
Published: January 2004

The ’hygiene hypothesis’ was popularized in the late 1980s to explain the high prevalence of atopic disordersin the developed countries. It links atopic disorders and the lack of early life infections. An association between the two is not novel and dates back to the beginnings of allergy, immunology and microbiology. Allergy and infection have always been closely related and the study ofone has often provided new insights into the pathobiology of the other. Early research into bacterial infections led to the discovery of the human immune system and the concept of allergy. An important relationship exists between parasite infections and the development of atopic disorders.

This review traces the long and intimate historical relationship between infection and allergy.
Mode of parotid involvement in external auditory canal carcinoma
Authors: Choi Jae Young , Choi Eun-Chang , Lee Ho-Ki , Yoo Jong-Bum , Kim Sun Goo , Lee Won-Sang
Published: January 2004

Until now, little was known about the mode of parotid involvement in external auditory canal (EAC) carcinoma. The incidence of parotid node metastasis and direct parotid invasion was examined in patients with EAC carcinoma. The study comprised 11 patients with squamous cell carcinomas (SCC) and 10 patients with adenoid cystic carcinomas (ACC). A retrospective review of the surgical specimens was undertaken with specific reference to parotid node metastasis and parotid invasion. Parotid node metastasis was noted only in two cases of advanced staged SCC, whereas none of the ACC patients showed parotid node metastasis. Direct parotid invasion occurred only in advanced staged SCC,however, it did occur in early stage ACC. Our data indicated that elective parotidectomy for control of occult parotid node metastasis is necessary only in advanced SCC carcinoma, whereas parotid management to secure adequate safety margins is mandatory for advanced SCC and all cases of ACC.
Incidental magnetic resonance image sinus abnormalities in asymptomatic Australian children
Authors: Lim Wye-Keat , Ram Bhaskar , Fasulakis Stephen , Kane Kevin J.
Published: January 2004

Plain X-rays, computed tomography (CT) and magnetic resonance imaging (MRI) scans performed for non-ENT reasons often reveal incidental sinus mucosal changes. These changes need to be correlated clinically before diagnosing rhinosinusitis. This study examined the prevalence of such changes in MRI scans in children up to age 16. Scans were scored using an adapted Lund-Mackay classification and were positive when one or more sinuses showed abnormalities. Randomly selected scans in the retrospective arm revealed a prevalence of 20 of 62 (32 3 per cent). In the prospective arm 45 of 60 children were defined as truly asymptomatic, of which 14 scans (31 per cent) were positive. Other studies in adults and children using CT and MRI report a prevalence range of roughly 30 to 45 per cent. This variability may be attributed to differences of study design, definitions of population age, definitions of asymptomatic and definition of abnormal sinus. Other plausible factors to explain regional differences are climate and frequency of upper respiratory tract infections.
Fine needle aspiration in chronic tonsillitis: reliable and valid diagnostic test
Authors: Kurien Mary , Sheelan Suchitra , Jeyaseelan L. , Bramhadathan  , Thomas Kurien
Published: January 2004

Fine needle aspiration (FNA) of the tonsil as a diagnostic tool in evaluating the microflora in chronic tonsillitis has not been popularized. A prospective study of 30 patients with chronic tonsillitis undergoing tonsillectomy was undertaken. FNA of the tonsil core was done under local/general anaesthesia. The reliability of the culture by FNA of the tonsil core was then validated with the reference (gold) standard which is the dissected tonsil core. The sensitivity of FNA culture as compared to core culture was 100 per cent and 93 per cent under general and local anaesthesia respectively. The positive predictive value of FNA culture as compared to core culture was 92 per centand 82 per cent for general and local anaesthesia respectively. These factors indicate that FNA of the tonsil core is reliable and valid. It can safely be performed as an out-patient procedure under local anaesthesia. This is reported for the first time. Identifying the bacterial organism within the infected tonsil for appropriate antibiotic therapy could revolutionize the management of chronic tonsillitis.
Pre- and intra-operative staging of the neck in a developing world practice
Authors: de Waal Patrick J. , Fagan Johannes J. , Isaacs Sedick
Published: January 2004

Most patients with squamous cancer of the head and neck treated at Groote Schuur Hospital are from a poor socio-economic background with a high prevalence of tuberculosis (TB), human immunodeficiency virus (HIV) and other infections that may cause cervical lymphadenopathy resulting in overstaging of the neck.

A retrospective review of 186 patients requiring therapeutic and elective neck dissection was undertaken and the sensitivity and specificity of clinical and intra-operative staging of the neck determined.

Results showed overall sensitivity of staging at 80.1 per cent. Specificity was 52.2 per cent. Staging of the N1, N2b and N2c necks had positive predictive values of 53.2, 65.8 and 68.2 per cent respectively. Occult nodal metastases were present in 32 per cent elective neck dissections (END)s. Specificity of intra-operative staging of the N0 neck was 33.3 per cent and sensitivity was 72.4 per cent.

Conclusions were that our indications for elective neck dissection are appropriate. The high false positive rates for staging of the N1, N2b and N2c necks, necessitate a change in management strategy.
Prevalence of back and neck pain amongst ENT consultants: national survey
Authors: Babar-Craig H. , Banfield G. , Knight J.
Published: January 2004

Back and neck pain is an established occupational disease for many professions. No previous studies have shown the association of back and neck pain with ENT surgery. Our objective was to determine the prevalence of neck and back pain in ENT consultants in the United Kingdom and which sub-specialities were most at risk. A national survey from 325 ENT consultants in the UK revealed that 72 per cent had either back pain or neck pain or even both. Of those with pain 53 per cent attributed their symptoms directly to ENT surgery. Highest figures were received from otologists, related to microscope work and prolonged sitting. The importance of these findings has demonstrated the lack of awareness and adequate training to prevent long-term disability in ENT surgeons.
Management of an infected preauricular sinus, using a lacrimal probe
Authors: Coatesworth A. P. , Patmore H. , Jose J.
Published: January 2004

This paper describes a technique for managing a preauricular abscess that allows drainage of the pus, with little or no disturbance to the underlying sinus, making any subsequent surgery more straight forward.
Emergency management of tracheo-brachiocephalic artery fistula
Authors: Anthony R. , Newbegin C. J. R.
Published: January 2004

The authors present a technique for emergency management of a tracheo-brachiocephalic artery fistula.
Chorda tympani neuroma masquerading as cholesteatoma
Authors: Hopkins C. , Chau H. , McGilligan J. A.
Published: January 2004

Facial nerve neuromas occur throughout the course of the facial nerve and its branches, however lesions occurring on the chorda tympani branch are exceptionally rare.

We present a case where the diagnosis was made intra-operatively; the patient was pre-operatively thought to have had a cholesteatoma.

Total resection is the treatment of choice for these cases. Early diagnosis, aided by high resolution computed tomography (CT) scanning, will facilitate complete excision without damage to the facial nerve itself or the ossicular chain. The slow growing nature of the neuroma is likely to allow compensatory mechanisms to occur without the patient experiencing dysgeusia. As with any rarity the diagnosis can only be made with a high index of suspicion.
Septal perforation secondary to Mycobacterium kansasii infection
Authors: Bennett A. M. D. , Patel N. , Kotecha B. , Al-Okati A.
Published: January 2004

We report the first recorded case of a septal perforation caused by Mycobacterium kansasii. This atypical mycobacterium is finding increasing prevalence with the increasing incidence and longevity of human immunodeficiency (HIV) infections. Cases of chest infection, sinusitis, septic arthritis, osteomyelitis, pericarditis, brain abscess, cutaneous and oral lesions have all now been reported.This discovery represents a rare but important differential in the aetiology of septal perforation.
Mucoepidermoid carcinoma of the larynx: report of three cases
Authors: Prgomet Drago , Bilić Mario , Bumber Željko , Manojlović Spomenka , Katić Vlado
Published: January 2004

Mucoepidermoid carcinoma of the larynx is very rare, with only a few individual cases or studies in small patient groups reported in the literature. Treatment modalities for this type of carcinoma are not uniform; in addition, errors in the recognition and pathologic diagnosis are not uncommon. During the period 1991–2000, 771 cases of malignant laryngeal tumours were recorded and histologically verified at the University Department of Otorhinolaryngology and Cervicofacial Surgery, Zagreb University Hospital Centre, three of them were mucoepidermoid supraglottic carcinomas. The experience acquired in the treatment of these tumours is presented along with a review of the literature.
Angiomyoma in the submandibular gland: a rare location for a ubiquitous tumour
Authors: Ide Fumio , Mishima Kenji , Saito Ichiro
Published: January 2004

Angiomyoma is a common soft tissue tumour of the head and neck that sometimes presents to the otolaryngologist; however, it seldom occurs in the major salivary glands. We present a case of angiomyoma arising in the submandibular gland, a tumour not described previously in the English literature.
Osteoradionecrosis of the hyoid presenting as a cause of intractable neck pain following radiotherapy and the role of magnetic resonance image scanning to aid diagnosis
Authors: Smith W. K. , Pfleiderer A. G. , Millet B.
Published: January 2004

Osteoradionecrosis of the hyoid has been reported rarely in the worldwide literature. We present the case of a 56-year-old gentleman who presented with intractable neck pain, following surgery and radiotherapy for a T2N2cM0 tongue base carcinoma, to highlight the need to consider osteoradionecrosis of the hyoid rather than recurrence of the carcinoma as the cause of such symptoms. The previously unreported appearance of osteoradionecrosis of the hyoid on a magnetic resonance image (MRI) scan and the use ofthis investigation to aid diagnosis is discussed.
Heparin-Induced Hyponatremia
Authors: Norman N Elizabeth , Sneed Angela M , Brown Christine , Ellis Cecilia A , Minard Gayle , Brown Rex O
Published: January 2004

OBJECTIVE

To report a case of hyponatremia in a patient receiving systemic unfractionated heparin (UFH) therapy and parenteral nutrition.

CASE SUMMARY

A 70-year-old African American woman was started on parenteral nutrition for postoperative ileus following an elective surgical procedure. Three days later, she was diagnosed with a pulmonary embolism and intravenous UFH therapy was initiated. During the 7-day course of UFH therapy, the patient's serum sodium concentration steadily declined and urine sodium concentration progressively increased. Physical examination revealed no signs or symptoms of hypo- or hypervolemia. The patient's serum potassium concentration increased modestly, although significant hyperkalemia was not observed. After discontinuation of UFH, serum concentrations of both sodium and potassium returned to baseline levels.

DISCUSSION

Although heparin-induced hyperkalemia is well documented, cases associated with substantial hyponatremia have been reported less frequently. An objective causality assessment revealed that the adverse drug reaction was probable in this case. Hyponatremia and hyperkalemia result from the antagonism of aldosterone by UFH within the zona glomerulosa of the adrenal glands.

CONCLUSION

The use of UFH may result in significant hyponatremia as well as hyperkalemia. Reversal of these electrolyte disturbances occurs after discontinuation of heparin.