bluuebunny/crossref_metadata_2025 huggingface dataset:
Computer‐aided detection of breast masses on full field digital mammograms
Authors: Wei Jun , Sahiner Berkman , Hadjiiski Lubomir M. , Chan Heang‐Ping , Petrick Nicholas , Helvie Mark A. , Roubidoux Marilyn A. , Ge Jun , Zhou Chuan
Published: September 2005

We are developing a computer‐aided detection (CAD) system for breast masses on full field digital mammographic (FFDM) images. To develop a CAD system that is independent of the FFDM manufacturer's proprietary preprocessing methods, we used the raw FFDM image as input and developed a multiresolution preprocessing scheme for image enhancement. A two‐stage prescreening method that combines gradient field analysis with gray level information was developed to identify mass candidates on the processed images. The suspicious structure in each identified region was extracted by clustering‐based region growing. Morphological and spatial gray‐level dependence texture features were extracted for each suspicious object. Stepwise linear discriminant analysis (LDA) with simplex optimization was used to select the most useful features. Finally, rule‐based and LDA classifiers were designed to differentiate masses from normal tissues. Two data sets were collected: a mass data set containing 110 cases of two‐view mammograms with a total of 220 images, and a no‐mass data set containing 90 cases of two‐view mammograms with a total of 180 images. All cases were acquired with a GE Senographe 2000D FFDM system. The true locations of the masses were identified by an experienced radiologist. Free‐response receiver operating characteristic analysis was used to evaluate the performance of the CAD system. It was found that our CAD system achieved a case‐based sensitivity of 70%, 80%, and 90% at 0.72, 1.08, and 1.82 false positive (FP) marks/image on the mass data set. The FP rates on the no‐mass data set were 0.85, 1.31, and 2.14 FP marks/image, respectively, at the corresponding sensitivities. This study demonstrated the usefulness of our CAD techniques for automated detection of masses on FFDM images.
Investigations in x‐ray computed tomography polyacrylamide gel dosimetry
Authors: Hilts Michelle
Published: September 2005

Polyacrylamide gels (PAGs) are radiosensitive materials currently under development for use as three‐dimensional (3D) dosimeters in radiation therapy. Dose information is recorded in the gels and extracted through imaging. X‐ray computed tomography (CT) has emerged as a promising gel imaging method due to a change in gel density that occurs upon irradiation. The accessibility of CT technology to cancer hospitals makes CT read out clinically attractive; however, the technique remains of limited clinical use due in part to poor dose resolution. This thesis investigates the use of CT for extracting dose information from PAGs with an overall goal of improving achievable dose resolution. Thesis results are divided into three studies: a gel‐compositional study, a study of noise and dose resolution, and a digital filtering study. The first study investigates the effects of gel composition on PAG CT dose response and the underlying density change. Results indicate dramatic variation in CT dose response sensitivity and range with gel composition. A model is developed to describe gel density change with dose, revealing two fundamental properties of the density to dose response: the density change per unit polymer yield is highest for gels with low and high concentrations of crosslinking molecules, and dose response sensitivity is linearly dependent on the total concentration of monomers in the gel. The second study investigates strategies for minimizing noise in CT polymer gel dosimetry and assesses system performance. Specifically, the effects of phantom design, scanning technique, and voxel size on image noise are investigated and the effect of scanning protocol on imaging time is established. The dose resolution achievable with an optimized system is then calculated, given voxel size and imaging time constraints, and compared with published values for magnetic resonance imaging (MRI) and optical CT gel dosimetry. The third study investigates the potential of image filtering for improved dose resolution in CT gel dosimetry. CT image noise is characterized and appropriate filters are tested on a CT image of a PAG irradiated with a clinically relevant dose distribution. Filter performance is found to vary dramatically, with the best filters more than halving the dose resolution without significantly distorting the spatial distribution of dose. In summary, this thesis provides insight into the fundamental nature of PAG density to dose response, develops strategies for minimizing image noise, quantifies system performance, and demonstrates that digital image filtering is an effective tool to provide additional improvements to dose resolution.
Statistical process control for radiotherapy quality assurance
Authors: Pawlicki Todd , Whitaker Matthew , Boyer Arthur L.
Published: September 2005

Every quality assurance process uncovers random and systematic errors. These errors typically consist of many small random errors and a very few number of large errors that dominate the result. Quality assurance practices in radiotherapy do not adequately differentiate between these two sources of error. The ability to separate these types of errors would allow the dominant source(s) of error to be efficiently detected and addressed. In this work, statistical process control is applied to quality assurance in radiotherapy for the purpose of setting action thresholds that differentiate between random and systematic errors. The theoretical development and implementation of process behavior charts are described. We report on a pilot project is which these techniques are applied to daily output and flatness/symmetry quality assurance for a photon beam in our department. This clinical case was followed over . As part of our investigation, we found that action thresholds set using process behavior charts were able to identify systematic changes in our daily quality assurance process. This is in contrast to action thresholds set using the standard deviation, which did not identify the same systematic changes in the process. The process behavior thresholds calculated from a subset of the data detected a 2% change in the process whereas with a standard deviation calculation, no change was detected. Medical physicists must make decisions on quality assurance data as it is acquired. Process behavior charts help decide when to take action and when to acquire more data before making a change in the process.
Refraction‐enhanced tomography of mouse and rabbit lungs
Authors: Sera T. , Uesugi K. , Yagi N.
Published: September 2005

In order to evaluate the effectiveness of edge enhancement by refraction in computed tomography, images of a cross section of a euthanized mouse thorax were recorded at low (20 keV) and high (72 keV) x‐ray energies at a spatial resolution of about . Compared with the images obtained with the detector at 30 cm from an object, when the object was located at 113 cm from the detector, the contrast between tissues and air was improved at both energies. The improvement was more pronounced at 72 keV where the absorption contrast was weaker. This effect was due to refraction at the surfaces of alveolar membranes and small airways which creates areas with apparently high and low linear attenuation coefficients within tissues. The edge enhancement by refraction was also effective in images of a euthanized rabbit thorax at x‐ray energies of 40 and 70 keV at a spatial resolution of about 0.15 mm. These results raise the possibility that the refraction contrast may be utilized to obtain a high‐resolution tomographic image of human lung and bone with low dose.
Spectral discrimination of Čerenkov radiation in scintillating dosimeters
Authors: Frelin A‐M. , Fontbonne J‐M. , Ban G. , Colin J. , Labalme M. , Batalla A. , Isambert A. , Vela A. , Leroux T.
Published: September 2005

Radiation therapy accelerators require highly accurate dose deposition and the output must be monitored frequently and regularly. Ionization chambers are the primary tool for this control, but their size, their high voltage needed, and the correction needed for electrons make them unsuitable for use during patient treatment. We have developed a small (1‐mm‐diam and 1‐mm‐long active part), flexible, and water‐equivalent dosimeter. It is suitable for photon and electron beams without corrections, and performs on line dose measurements. This detector is based on only one scintillating fiber and a CCD camera. A new signal processing is used to remove the effect of Čerenkov radiation background, which only requires a preliminary calibration. Central‐axis depth‐dose distribution comparisons have been achieved with standard ionization chambers, over a range from 8 to 25 MV photons and from 6 to 21 MeV electrons in order to validate this calibration. Results show a very good agreement, with less than 1% difference between the two detectors.
Feasibility of a fast inverse dose optimization algorithm for IMRT via matrix inversion without negative beamlet intensities
Authors: Goldman S. P. , Chen J. Z. , Battista J. J.
Published: September 2005

A fast optimization algorithm is very important for inverse planning of intensity modulated radiation therapy (IMRT), and for adaptive radiotherapy of the future. Conventional numerical search algorithms such as the conjugate gradient search, with positive beam weight constraints, generally require numerous iterations and may produce suboptimal dose results due to trapping in local minima. A direct solution of the inverse problem using conventional quadratic objective functions without positive beam constraints is more efficient but will result in unrealistic negative beam weights. We present here a direct solution of the inverse problem that does not yield unphysical negative beam weights. The objective function for the optimization of a large number of beamlets is reformulated such that the optimization problem is reduced to a linear set of equations. The optimal set of intensities is found through a matrix inversion, and negative beamlet intensities are avoided without the need for externally imposed ad‐hoc constraints. The method has been demonstrated with a test phantom and a few clinical radiotherapy cases, using primary dose calculations. We achieve highly conformal primary dose distributions with very rapid optimization times. Typical optimization times for a single anatomical slice (two dimensional) (head and neck) using a LAPACK matrix inversion routine in a single processor desktop computer, are: for 500 beamlets; for 1000 beamlets; for 2000 beamlets; and for 3000 beamlets. Clinical implementation will require the additional time of a one‐time precomputation of scattered radiation for all beamlets, but will not impact the optimization speed. In conclusion, the new method provides a fast and robust technique to find a global minimum that yields excellent results for the inverse planning of IMRT.
Major Histocompatibility Complex Class II (HLA-DRB and -DQB) Allele Frequencies in Botswana: Association with Human Immunodeficiency Virus Type 1 Infection
Authors: Ndung'u Thumbi , Gaseitsiwe Simani , Sepako Enoch , Doualla-Bell Florence , Peter Trevor , Kim Soyeon , Thior Ibou , Novitsky Vladimir A. , Essex Max
Published: September 2005

Southern Africa is facing an unprecedented public health crisis due to the high prevalence of human immunodeficiency virus type 1 (HIV-1). Vaccine development and testing efforts, mainly based on elicitation of HIV-specific T cells, are under way. To understand the role of human leukocyte antigen (HLA) class II alleles in HIV pathogenesis and to facilitate HLA-based HIV-1 vaccine design, we analyzed the frequencies of HLA class II alleles within the southern African country of Botswana. Common HLA class II alleles were identified within the Batswana population through the molecular genotyping of DRB and DQB1 loci. The DRB1 allele groups DRB1*01, DRB1*02/15, DRB1*03, DRB1*11, and DRB1*13 were encountered at frequencies above 20%. Within the DQB1 locus, DQB1*06 (47.7%) was the most common allele group, followed by DQB1*03 (39.2%) and DQB1*04 (25.8%). We found that DRB1*01 was more common in HIV-negative than in HIV-positive individuals and that those who expressed DRB1*08 had lower median viral loads. We demonstrate that the frequencies of certain HLA class II alleles in this Batswana population differ substantially from those in North American populations, including African-Americans. Common allele groups within Botswana cover large percentages of other African populations and could be targeted in regional vaccine designs.
Avidity Determinations for
Haemophilus influenzae
Type b Anti-Polyribosylribitol Phosphate Antibodies
Authors: Romero-Steiner Sandra , Holder Patricia F. , Gomez de Leon Patricia , Spear Willie , Hennessy Thomas W. , Carlone George M.
Published: September 2005

Determination of antibody avidity measurements can be difficult in human serum depending on the population evaluated. We evaluated three approaches for the determination of antibody avidity for immunoglobulin G (IgG). These approaches were (i) elution of bound antibody with increasing concentrations of a chaotropic agent using a single serum dilution, (ii) binding interference of multiple serum dilutions by a single concentration of a chaotrope, and (iii) elution of multiple serum dilutions by a single concentration of a chaotrope. Parameters that affect the determination of avidity measurements and their limitations were evaluated with pre- and post-
Haemophilus influenzae
type b conjugate vaccination sera (
n
= 89). We determined that elution of low-avidity antibodies present in multiple dilutions of the serum sample by a single concentration of a chaotrope (0.15 M sodium thiocyanate [NaSCN]) was optimal for the determination of avidity measurements throughout a wide range of IgG concentrations (0.94 to 304.6 μg/ml). The percent reduction in concentration as determined by the elution assay with 0.15 M NaSCN correlated highly (
r
= 0.84) with weighted averages obtained by an elution assay with multiple solutions of NaSCN. The correlation (
r
= 0.57) between elution and binding interference, when a single concentration of a chaotrope was used, was lower than the correlation between the two elution methods (
r
= 0.84). We found that the serum dilution, the heterogeneity of the antibody population, and the concentration of the chaotrope were the primary variables affecting avidity determinations. In this study, we present multiple analysis methods depending on the methodology used. We also present the factors that affect the analysis of avidity determinations given the polyclonal nature of human sera. This experimental approach should benefit the evaluation of similar antibodies induced by other bacterial polysaccharide vaccines.
Enzyme-Linked Immunosorbent Assays for Detection of Equine Antibodies Specific toSarcocystis neuronaSurface Antigens
Authors: Hoane Jessica S. , Morrow Jennifer K. , Saville William J. , Dubey J. P. , Granstrom David E. , Howe Daniel K.
Published: September 2005

Sarcocystis neuronais the primary causative agent of equine protozoal myeloencephalitis (EPM), a common neurologic disease of horses in the Americas. We have developed a set of enzyme-linked immunosorbent assays (ELISAs) based on the four major surface antigens ofS. neurona(SnSAGs) to analyze the equine antibody response toS. neurona. The SnSAG ELISAs were optimized and standardized with a sample set of 36 equine sera that had been characterized by Western blotting against totalS. neuronaparasite antigen, the current gold standard forS. neuronaserology. The recombinant SnSAG2 (rSnSAG2) ELISA showed the highest sensitivity and specificity at 95.5% and 92.9%, respectively. In contrast, only 68.2% sensitivity and 71.4% specificity were achieved with the rSnSAG1 ELISA, indicating that this antigen may not be a reliable serological marker for analyzing antibodies againstS. neuronain horses. Importantly, the ELISA antigens did not show cross-reactivity with antisera toSarcocystis fayeriorNeospora hughesi, two other equine parasites. The accuracy and reliability exhibited by the SnSAG ELISAs suggest that these assays will be valuable tools for examining the equine immune response againstS. neuronainfection, which may help in understanding the pathobiology of this accidental parasite-host interaction. Moreover, with modification and further investigation, the SnSAG ELISAs have potential for use as immunodiagnostic tests to aid in the identification of horses affected by EPM.
Assessment of Interleukin-12, Gamma Interferon, and Tumor Necrosis Factor Alpha Secretion in Sera from Mice Fed with Dietary Lipids during Different Stages ofListeria monocytogenesInfection
Authors: Puertollano María A. , Cruz-Chamorro Lidia , Puertollano Elena , Pérez-Toscano María T. , Álvarez de Cienfuegos Gerardo , de Pablo Manuel A.
Published: September 2005

Recent experimental observations have determined that long-chainn-3 polyunsaturated fatty acids suppress immune functions and are involved in the reduction of infectious disease resistance. BALB/c mice were fed for 4 weeks with one of four diets containing either olive oil (OO), fish oil (FO), hydrogenated coconut oil, or a low fat level. Interleukin-12p70 (IL-12p70), gamma interferon (IFN-γ), and tumor necrosis factor alpha (TNF-α) production in the sera of mice fed these diets and challenged withListeria monocytogeneswere determined by enzyme-linked immunosorbent assay. In addition, bacterial counts from spleens of mice were carried out at 24, 72, or 96 h of infection. Here, we quantified an initial diminution of production of both IL-12p70 and IFN-γ, which appear to play an important role in the reduction of host resistance toL. monocytogenesinfection. In addition, an efficient elimination ofL. monocytogeneswas observed in spleens of mice fed a diet containing OO at 96 h of infection, despite reductions in IL-12p70 and TNF-α production, suggesting an improvement of immune resistance. Overall, our results indicate that the initial reduction of both IL-12 and IFN-γ production beforeL. monocytogenesinfection represents the most relevant event that corroborates the impairment of immune resistance byn-3 polyunsaturated fatty acids during the different stages of infection. However, we speculate that the modulation of other cytokines must be also involved in this response, because the alteration of cytokine production in mice fed an FO diet in a late phase ofL. monocytogenesinfection was similar to that in mice fed OO, whereas the ability to eliminate this bacterium from the spleen was improved in the latter group.
Evaluation of Three Immunoassays Used for Detection of Anti-Rubella Virus Immunoglobulin M Antibodies
Authors: Dimech Wayne , Panagiotopoulos Lena , Marler Joan , Laven Nicolas , Leeson Susan , Dax Elizabeth M.
Published: September 2005

Three automated assays (Abbott AxSYM, Bayer ADVIA Centaur, and bioMerieux VIDAS) used for the detection of rubella virus-specific immunoglobulin M were evaluated. A total of 57 samples from individuals with evidence of infection with rubella virus were used to estimate sensitivity, and 220 samples from blood donors and individuals attending an antenatal clinic who had no evidence of recent infection were used to estimate specificity. Seroconversion panels comprising an additional 31 samples from four individuals were used to determine clinical sensitivity. Samples containing potentially cross-reacting substances were also tested. The sensitivities of the three assays ranged from 84.2 to 96.5%, and the specificities ranged from 96.8 to 99.9%. The Abbott AxSYM assay detected more reactive samples than the other two assays when a panel of 57 positive samples was tested. Bayer ADVIA Centaur detected more reactive samples in the seroconversion panels than the other two assays. All three assays evaluated reported a reactive result in 1 or more of the 48 samples containing potentially cross-reacting analytes. The assays demonstrated comparable performance in testing of a well-characterized panel of samples.
Monoclonal Antibodies against
Enterocytozoon bieneusi
of Human Origin
Authors: Sheoran Abhineet S. , Feng Xiaochuan , Singh Inderpal , Chapman-Bonofiglio Susan , Kitaka Sabrina , Hanawalt Joel , Nunnari John , Mansfield Keith , Tumwine James K. , Tzipori Saul
Published: September 2005

Enterocytozoon bieneusi
is clinically the most significant among the microsporidia infecting humans, causing chronic diarrhea, wasting, and cholangitis in individuals with human immunodeficiency virus/AIDS. The lack of immune reagents is largely due to the absence of methods for laboratory propagation of
E. bieneusi
. We recently described a procedure for the concentration and purification of spores from diarrheic stool of infected humans. Purified spores were used to immunize mice for production and screening of monoclonal antibodies (MAbs) against
E. bieneusi
. The eight immunoglobulin M MAbs generated and fully characterized did not cross-react with other human microsporidia or with other microorganisms normally present in stool. One of the MAbs, 2G4, reacted with
E. bieneusi
spores in stools from monkeys and humans, without background fluorescence, which makes it an ideal diagnostic reagent. It also recognizes intracellular stages of the parasite and will be suitable for determining tissue distribution of
E. bieneusi
in infected hosts. At least two immunodominant antigens of
E. bieneusi
of 33,000 and 35,000 Da exist, which were recognized by rabbit and mouse antisera. The availability of MAbs against
E. bieneusi
will simplify considerably the diagnosis of this infection in humans and will provide tools for epidemiologic investigations regarding the true prevalence of the infection in various human and mammalian populations and the environmental sources of infection.
Human Immunodeficiency Virus Infection and Levels of Dehydroepiandrosterone Sulfate in Plasma among Indians
Authors: Kandathil A. J. , Kannangai R. , David S. , Selvakumar R. , Job V. , Abraham O. C. , Sridharan G.
Published: September 2005

The shift in cytokine profile during human immunodeficiency virus (HIV) disease progression is influenced by dehydroepiandrosterone sulfate (DHEAS) level. Radioimmunoassay was used to measure plasma DHEAS for 30 treatment-naïve HIV-infected and 30 uninfected individuals. There was a significant negative correlation of viral load with DHEAS level (P< 0.05). Further studies of the use of DHEAS levels for monitoring HIV patients economically are warranted.
Utilization of Follow-Up Specimens from Viremic Blood Donors To Assess the Value of West Nile Virus Immunoglobulin G Avidity as an Indicator of Recent Infection
Authors: Prince Harry E. , Lapé-Nixon Mary , Busch Michael P. , Tobler Leslie H. , Foster Gregory A. , Stramer Susan L.
Published: September 2005

The value of West Nile virus immunoglobulin G avidity for distinguishing recent from past infection was investigated using 348 follow-up specimens from 170 viremic blood donors. Low avidity accurately indicated infection within the previous 4 months. However, due to rapid avidity maturation in some individuals, high avidity did not accurately indicate past infection.
Comparison of the Antibodies in Lymphocyte Supernatant and Antibody-Secreting Cell Assays for Measuring Intestinal Mucosal Immune Response to a Novel Oral Typhoid Vaccine (M01ZH09)
Authors: Kirkpatrick B. D. , Bentley Matthew D. , Thern Anette M. , Larsson Catherine J. , Ventrone Cassandra , Sreenivasan Meera V. , Bourgeois Lou
Published: September 2005

Antibody-secreting cell (ASC) and antibodies in lymphocyte supernatant (ALS) assays are used to assess intestinal mucosal responses to enteric infections and vaccines. The ALS assay, performed on cell supernatants, may represent a convenient alternative to the more established ASC assay. The two methods, measuring immunoglobulin A toSalmonella entericaserovar Typhi lipopolysaccharide, were compared in volunteers vaccinated with a live-attenuated typhoid vaccine M01ZH09. The specificity of the ALS assay compared to the ASC assay was excellent (100%), as was sensitivity (82%). The ALS assay was less sensitive than the ASC assay at ≤42 spots/106peripheral blood lymphocytes.
Molecular Biology of Pseudorabies Virus: Impact on Neurovirology and Veterinary Medicine
Authors: Pomeranz Lisa E. , Reynolds Ashley E. , Hengartner Christoph J.
Published: September 2005

Pseudorabies virus (PRV) is a herpesvirus of swine, a member of theAlphaherpesvirinaesubfamily, and the etiological agent of Aujeszky's disease. This review describes the contributions of PRV research to herpesvirus biology, neurobiology, and viral pathogenesis by focusing on (i) the molecular biology of PRV, (ii) model systems to study PRV pathogenesis and neurovirulence, (iii) PRV transsynaptic tracing of neuronal circuits, and (iv) veterinary aspects of pseudorabies disease. The structure of the enveloped infectious particle, the content of the viral DNA genome, and a step-by-step overview of the viral replication cycle are presented. PRV infection is initiated by binding to cellular receptors to allow penetration into the cell. After reaching the nucleus, the viral genome directs a regulated gene expression cascade that culminates with viral DNA replication and production of new virion constituents. Finally, progeny virions self-assemble and exit the host cells. Animal models and neuronal culture systems developed for the study of PRV pathogenesis and neurovirulence are discussed. PRV serves as a self-perpetuating transsynaptic tracer of neuronal circuitry, and we detail the original studies of PRV circuitry mapping, the biology underlying this application, and the development of the next generation of tracer viruses. The basic veterinary aspects of pseudorabies management and disease in swine are discussed. PRV infection progresses from acute infection of the respiratory epithelium to latent infection in the peripheral nervous system. Sporadic reactivation from latency can transmit PRV to new hosts. The successful management of PRV disease has relied on vaccination, prevention, and testing.
Hydration of the carbonyl group  Acetic acid catalysis in the co-operative mechanism
Authors: Hsieh Yih-Huang , Weinberg Noham , Yang Kiyull , Kim Chan-Kyung , Shi Zheng , Wolfe Saul
Published: September 2005

In a co-operative reaction, solvent molecules, specifically water molecules, participate actively in the mechanism to circumvent the formation of charged intermediates. This paper extends our earlier theoretical treatment of the neutral co-operative hydration of acetone to include general acid catalysis by acetic acid. As before, the predominant neutral channel employs three catalytic water molecules. The principal acetic acid catalyzed channels employ one catalytic water molecule and, in approximately equal proportions, one or both oxygens of the carboxyl group. The theoretical rate constant for general acid catalysis is calculated to be 0.49 M1s1at 298 K. This compares to an estimated experimental value of 0.30 M1s1for acetic acid catalyzed hydration of acetone at 298 K in water solvent, determined by using the18O-isotope shift in the13C NMR spectrum of 2-13C-labelled acetone as a kinetic probe. It is concluded that the notion of co-operativity can be extended to include general acid catalysis of the hydration of a carbonyl group in water solvent. This creates an obvious problem for the generally accepted view that multistep ionic mechanisms are operative in the low dielectric media that exist at the active sites of hydrolytic enzymes. The relevance of this finding to the mechanisms of action of β-lactam antibiotics has been noted.Key words: hydration, reaction mechanism, co-operativity, general acid catalysis, ab initio, SCRF,18O-isotope shift.
Recent advances in cyclohydrocarbonylation reactions
Authors: Chiou Wen-Hua , Lee Seung-Yub , Ojima Iwao
Published: September 2005

This article describes recent advances in the cyclohydrocarbonylation reactions catalyzed by transition-metal complexes and their applications in organic synthesis as a review covering the relevant literature up to the middle of 2004. The reactions are categorized into four types, i.e., intramolecular amidocarbonylation reactions, intramolecular aminocarbonylation reactions, cyclohydrocarbonylation reactions involving carbonnucleophiles, and other cyclohydrocarbonylation reactions. Cyclohydrocarbonylation reactions provide efficient routes to various monocyclic, bicyclic, and polycyclic compounds as a one-step cascade process or a one-pot process. Reaction mechanisms for these cascade processes are discussed as needed for clarification. The heterocyclic and carbocyclic compounds, thus obtained, can be further transformed to specific targets. Examples of such applications are also discussed.Key words: catalysis, cyclohydrocarbonylation, hydroformylation, amidocarbonylation, cyclization, regioselectivity, aldehydes, regioselective, cascade, heterocycles, rhodium.
Synthesis of a novel photocatalyst, ZnBiVO4, for the photodecomposition of H2S
Authors: Kale B B , Baeg Jin-Ook , Yoo Jin S , Lee Sang Mi , Lee Chul Wee , Moon Sang-Jin , Chang Hyunju
Published: September 2005

A novel metal-oxide photocatalyst, ZnBiVO4, was investigated for the photodecomposition of hydrogen sulfide. ZnBiVO4 was prepared using the solid-state method, as well as a solution route for the first time. Oxides of zinc, bismuth, and vanadium were used for the solid-state method, whereas the respective metal salts were used as precursors for the solution route synthesis. The microstructure of the newly prepared ZnBiVO4 was examined using XRD and FESEM. Tetragonal and monoclinic crystallite systems were observed in this ternary oxide system. Nanocrystalline ZnBiVO4 was obtained through the solution route. The catalyst was also characterized using UVvisible diffuse reflectance spectroscopy to evaluate its band gap. Photodecomposition of H2S using this catalyst was observed for the first time. The influence of preparation methods on the photocatalytic activity of ZnBiVO4 was examined and it was observed that the ZnBiVO4 prepared by the solution route led to a higher photocatalytic activity during H2S decomposition. It is noteworthy that the hydrogen evolution was enhanced by 100% using ZnBiVO4 prepared by the solution route as compared with the ZnBiVO4 prepared by the solid-state method.Key words: photocatalyst, ZnBiVO4, hydrogen sulfide, metal oxide, photodecomposition.
Double elimination protocol for the synthesis of arylene ethynylenes containing heteroaromatic rings
Authors: Orita Akihiro , Ye Fangguo , Babu Govindarajulu , Ikemoto Tomohiro , Otera Junzo
Published: September 2005

The double elimination reaction of β-substituted sulfones offers a versatile strategy for synthesis of arylene ethynylene kits containing heteroaromatic rings. A sequence of aldol reaction between α-sulfonyl carbanion and aldehyde, trapping the resulting aldolate to give β-substituted sulfone, and double elimination of this intermediate can be integrated in one pot. This protocol allows thiophene, pyridine, and ferrocene units to be accommodated in phenylene ethynylene arrays.Key words: aryleneethynylenes, heteroaromatic rings, ferrocene, double elimination, sulfones.
Efficient synthesis of the nonamannoside residue of high mannose glycoproteins
Authors: Jiang Lu , Chan Tak Hang
Published: September 2005

An efficient synthesis of the nonamannoside residue 1 of high mannose glycoproteins was achieved using an oligomer-supported solution synthesis with low-molecular-weight polyethylene glycol as the anchor. The synthesis required only five coupling steps from only two monosaccharide building blocks with an overall yield of 12%.Key words: nonamannoside, oligosaccharide synthesis, soluble polymer support synthesis, glycoproteins.
Rhodium-catalyzed C-HCOolefin coupling reactions  A chelation-assisted direct carbonylation at the ortho CH bond in the benzene ring of 2-arylpyridines
Authors: Chatani Naoto , Uemura Takeshi , Asaumi Taku , Ie Yutaka , Kakiuchi Fumitoshi , Murai Shinji
Published: September 2005

The reaction of 2-arylpyridines with ethylene and carbon monoxide in the presence of a catalytic amount of Rh4(CO)12results in selective carbonylation at the ortho CH bond. The reaction is heavily dependent on the solvents used, with DMA (N,N-dimethylacetamide) being the solvent of choice. Steric factors are also important determinants of the efficiency of the reaction.Key words: CH bond activation, carbonylation, chelation, rhodium, carbon monoxide.
Synthesis and catalysed hydroboration of styryl sulfonamides
Authors: Wynberg Natalie A , Leger Lisa J , Conrad Maren L , Vogels Christopher M , Decken Andreas , Duffy Stephen J , Westcott Stephen A
Published: September 2005

We have prepared the aryl sulfonamides 4,4′-R-C6H4SO2NHC6H4CH=CH2 (R = CH3, 1a; NO2, 1b) by addition of 2 equiv. of 4-vinylaniline to the corresponding sulfonyl chlorides. The disulfonamides 4,4,4′-(R-C6H4SO2)2NC6H4CH=CH2 (R = CH3, 2a; NO2, 2b) were also prepared using 4-vinylaniline and 2 equiv. of the sulfonyl chlorides in the presence of DMAP. Although hydroborations of sulfanilamide derivatives 1 suffered from competing hydrogenation reactions, judicious choice of the transition metal catalyst gave selective formation of either the primary or secondary boronate esters in hydroborations of 2a.Key words: boronate esters, catalysed hydroborations, sulfanilamides, vinylaniline.
Phosphino-indenyl complexes of nickel(II)
Authors: Groux Laurent F , Bélanger-Gariépy Francine , Zargarian Davit
Published: September 2005

The BH3-protected phosphinoindenyl ligand indenyl(CH2)2PPh2·BH3 was used in the preparation of (η5/3:η0-indenyl(CH2)2PPh2·BH3)Ni(PPh3)Cl, which has been characterized by NMR spectroscopy and X-ray diffraction studies. On the other hand, all attempts at preparing the closely related complex (η5/3:η1-indenyl(CH2)2PPh2)NiCl, in which the tethered phosphine moiety is coordinated to the Ni centre, were unsuccessful. One of these unsuccessful attempts yielded instead the novel indenyl-PCP pincer complex {κP,κC,κP-1,3-(CH2CH2PPh2)2-2-indenyl}NiCl, which has been characterized by X-ray diffraction studies.Key words: indenyl complexes, tethered phosphines, PCP pincer complexes.
Oxidative carbonylation of aniline with new cobalt catalytic systems
Authors: Orejón Aránzazu , Castellanos Aída , Salagre Pilar , Castillón Sergio , Claver Carmen
Published: September 2005

New neutral cobalt(II) complexes containing 2,9-bis(2-hydroxyphenyl)-1,10-phenanthroline and 2,9-bis(2-hydroxyphenyl)-2,2′-bipyridine ligands have been synthesized. These complexes are active catalysts in the oxidative carbonylation of aniline in 1-butanol and NaI as a promoter. The principal products obtained are N,N′-diphenylurea and 1-butyl-N-phenylcarbamate.Key words: cobalt, oxidative carbonylation, aniline, N,N′-diphenylurea, 1-butyl-N-phenylcarbamate.
Anion effects in the formation of the active catalyst in the Ruhrchemie  Rhône-Poulenc aqueous biphasic hydroformylation process. Are there any?
Authors: Kovács József , Joó Ferenc , Frohning Carl D
Published: September 2005

The water soluble [Rh(OAc)(CO)(mtppms)2] containing monosulfonated triphenylphosphine ligands was prepared for the first time and its hydrogenation was studied in aqueous solutions. In the presence of additional mtppms, the reaction yielded [RhH(CO)(mtppms)3], a close analogue of [RhH(CO)(mtppts)3], the immediate catalyst precursor in the Ruhrchemie  Rhône-Poulenc aqueous biphasic hydroformylation process. The extent of the [Rh(OAc)(CO)(mtppms)2] → [RhH(CO)(mtppms)3] transformation strongly depended on the solution pH, similar to the case of the hydrogenation of [RhCl(CO)(mtppms)2] studied earlier. In this respect, RhCl3·aq and Rh(OAc)3·aq can be used equally well for the in situ preformation of [RhH(CO)(mtppts)3], although the latter is the preferred choice in the industrial process.Key words: rhodium, water-soluble, hydrides, sulfonated phosphines, biphasic.
Synthesis and reactivity of the macrobicyclic complexes (1,5,8,12-tetraaza-17-oxabicyclo[10.5.2]nonadecane)cobalt(III) perchlorate ([Co(L1)(ClO4)](ClO4)2), [(chloro(1,4,8,11-tetraaza-17-oxabicyclo[9.5.3]nonadecane)cobalt(III) perchlorate ([Co(L2)(Cl)](ClO4)2), (4,8-dimethyl-1,4,8,11-tetraaza-17-oxabicyclo[9.5.3]nonadecane)cobalt(III) perchlorate ([Co(L3)(ClO4)](ClO4)2), and (5,8-dimethyl-1,5,8,12-tetraaza-17-oxabicyclo[10.5.2]nonadecane)cobalt(III) perchlorate ([Co(L4)(ClO4)](ClO4)2)  Crystal structure of the L2 complex
Authors: Rodopoulos Theo , Ishihara Koji , Rodopoulos Mary , Zaworotko M J , Maeder M , McAuley A
Published: September 2005

The potentially penta-coordinating ligands L2 and L3 have been synthesized by reaction of the 10-membered macrocycle 1,5-diaza-8-oxacyclodecane with either 1,9-dichloro-3,7-diazanonane-2,8-dione, and subsequent reduction of the diamide (3), or with 1,9-dichloro-3,7-(dimethyl)diazanonane-2,8-dione and reduction (L3). A similar procedure is outlined for the dimethylated macrobicycle (L4), based on the corresponding nine-membered 1,4-diaza-7-oxacyclononane. The Co(III) complexes of these ligands and of 1,5,8,12-tetraaza-17-oxabicyclo[10.5.2]nonadecane (L1) have been prepared. Spectrophotometric determinations on the L1 complex ion confirm the presence of two hydrogen ion related equilibria, one of which (pK = 2.2 ± 0.2) is associated with the proposed replacement of the apical ether oxygen by a water molecule that is bound to the metal centre and hydrogen bonded to the ether. The species derived from L1 and L2 exhibit remarkable kinetic stability. Studies on the anation of the [Co(L1)(H2O)](ClO4)3 with chloride ions in acidic media are consistent with the reaction of both the proton-related complex and the [Co(L1)(H2O)]3+ ion. Whilst complex ions containing two secondary NH groups maintain the metalion coordination in strongly acidic media, corresponding species with ligands containing all four tertiary amine sites are subject to attack by protons leading to a relatively facile demetallation of the complexes. The latter finding is supported by kinetic studies and mass spectrometric fragmentation patterns of the ions. Key words: cobalt(III), macrobicycle, hydrolysis, anation, spectroscopic analysis.
Microwave-accelerated, palladium-catalyzed carbonylative cyclization reactions of 2-iodophenol with alkynes  Rapid and efficient synthesis of chromen-2-one derivatives
Authors: Cao Hong , Xiao Wen-Jing
Published: September 2005

Rapid palladium-catalyzed carbonylative cyclization reactions of 2-iodophenol with various alkynes have been carried out by the use of commercially available molybdenum hexacarbonyl as a convenient and solid carbon monoxide source. The reactions were conducted at 160 °C for 30 min with microwave heating in the presence of DIEA and DMAP in 1,4-dioxane, and afford the corresponding chromen-2-one derivatives in good yields.Key words: microwave, palladium, carbonylation, 2-iodophenol, chromen-2-one.
Aluminium triflate as catalyst for epoxide ring-opening and esterification reactions  Mechanistic aspects
Authors: Terblans Yvette M , Huyser Johannes J , Huyser Michelle , Green Michael J , Young Desmond A , Sibiya Mike S
Published: September 2005

Al(CF3SO3)3 is a highly effective catalyst for the ring opening of epoxides with methanol, as well as for the esterification of carboxylic acids with alcohols. Factors that influence the rate of the ring opening of butene oxide with methanol and the esterification of acetic acid with n-propanol and ethanol were investigated. It was found that low concentrations (e.g., ~5 ppm) of Al(CF3SO3)3 catalyze the ring-opening reactions, whereas considerably higher concentrations are required for esterification reactions. Molecular modeling studies suggest that these differences can be rationalized in terms of the formation energies of the active intermediates of these reactions.Key words: epoxide, ring opening, esterification, aluminium triflate.
β Elimination of a phosphonate group from an alkoxyl radical — Intramolecular acylation using acylphosphonate derivatives as carbonyl group acceptors
Authors: Cho Chang Ho , Kim Sunggak
Published: September 2005

The possibility of β elimination of a phosphonate group in radical reactions was studied. The facile β elimination of the phosphonate group from an alkoxyl radical was observed for the first time, whereas the β elimination of the phosphonate group from an aminyl and an alkyl radical did not occur. On the basis of our findings, the use of an acylphosphonate as a carbonyl group radical acceptor was investigated. Radical cyclization of the acylphosphonate in the presence of hexamethylditin in benzene at 300 nm for 2 h gave a cyclopentanone or a cyclohexanone derivative in good yield without the formation of a direct reduction product. The reaction can be carried out in the presence of a catalytic amount of hexamethylditin (0.2 equiv.) under similar conditions. In addition, an alkyl phosphonothiolformate group can act as an alkylthiocarbonyl group equivalent radical acceptor, providing ready access to a thiolactone synthesis.Key words: radical, β elimination, acylation, cyclization, acylphosphonate.
Metal-catalysed tandem metathesis-hydrogenation reactions for the synthesis of carba analogues of cyclic peptides
Authors: Whelan Amanda N , Elaridi Jomana , Mulder Roger J , Robinson Andrea J , Jackson W Roy
Published: September 2005

Dicarba cyclic peptide analogues of the cystine-containing octapeptides octreotide, lanreotide, and vapreotide, all known somatostatin analogues, have been synthesized via an on-resin homogeneous metal-catalysed sequence involving ruthenium-catalysed ring-closing metathesis followed by rhodium-catalysed hydrogenation.Key words: dicarba-analogues of cystine-containing peptides, octreotide, vapreotide, and lanreotide; tandem ring-closing metathesis and hydrogenation.
Synthesis, thermal, electrochemical, and photophysical characterization of 1,5-bis(diarylamino)naphthalene derivatives as potential hole transport OLED materials
Authors: Shan Jingning , Yap Glenn PA , Richeson Darrin S
Published: September 2005

Novel 1,5-bis(diarylamino)naphthalene derivatives (19), which have potential as hole-transporting materials for electroluminescent devices, were obtained through palladium-catalyzed coupling of diarylamines and 1,5-dibromonaphthalene. The thermal, electrochemical, and photophysical properties of these compounds were examined and the effects of the N-aryl substituents on these properties were investigated. These materials possess glass transition temperatures (Tg) that range from 70131 °C and these values are related to the identity of the aryl substituents. Cyclic voltammetric measurements demonstrated that these compounds possess two reversible oxidation processes and were further used to estimate the HOMO energy levels of these materials by comparison with the ferrocene/ferrocenium couple. The intramolecular charge mobility, as gauged by the difference between the two oxidation potentials, indicates that compounds 18 have a similar degree of delocalization as meta-diaminobenzene derivatives while that of 9 is similar to TPD. Compounds 19 emit in the blue-green region and optical absorption and emission data for these materials can be rationalized in terms of the electronic donating properties of the aryl substituents. This data when combined with the electrochemically determined HOMO energies allowed estimation of the LUMO energy levels.Key words: hole transport materials, diaminonaphthalene, thermal analysis, palladium-catalyzed arylation.
Synthesis, structure determination, and hydroformylation activity ofN-heterocyclic carbene complexes of rhodium
Authors: Chen Austin C , Allen Daryl P , Crudden Cathleen M , Wang Ruiyao , Decken Andreas
Published: September 2005

The effect of ancillary phosphine ligands on the structure and hydroformylation activity of Rh-N-heterocyclic carbene complexes of type [Rh(IMes)(PR3)(CO)Cl] and [Rh(SIMes)(PR3)(CO)Cl] is described. Very high selectivities for the branched isomer (>95:5) were obtained in the hydroformylation of vinylarenes in all cases except for R = OPh. The new complexes were characterized spectroscopically and by X-ray crystallography.Key words: hydroformylation, rhodium, N-heterocyclic carbene, IMes.
Coordination chemistry of the tetrakis(2-hydroxyphenyl)ethene support mimic — Polymetallic magnesium, aluminum, and titanium derivatives
Authors: Verkerk Udo H , McDonald Robert , Stryker Jeffrey M
Published: September 2005

The crystal structures of magnesium, aluminum, and titanium coordination complexes of the structurally preorganized tetrakis(2-hydroxyphenyl)ethene are reported. As a result of the absence of steric shielding and the conformational flexibility of the ligand, pseudo-dimeric complexes are formed instead of crown- or raft-like compounds. The unsubstituted tetrakis(2-hydroxyphenyl)ethene ligand thus emulates the complexation characteristics of the sterically open calix[4]arene system.Key words: coordination chemistry, polymetallic, titanium complexes, magnesium complexes, aluminum complexes, tetrakis(2-hydroxyphenyl)ethene ligands, crystal structures.
In vitro and in vivo studies of neutral cyclometallated complexes against murine leukæmias
Authors: Edwards Gavin L , Black David St.C , Deacon Glen B , Wakelin Laurence PG
Published: September 2005

Cyclometallated µ-halogeno dimers derived from nitrogen donor ligands (1-phenylpyrazoles, 2-phenylpyridine, and 1-(2′-pyridyl)indole) were treated with unidentate nitrogen and phosphorus donor ligands to give a series of neutral monomeric palladium(II) and platinum(II) complexes. An initial prescreen of the complexes against the mouse lymphoid leukæmia cell line L1210 indicated that the complexes exhibited growth inhibitory activity over a relatively wide concentration range. Two factors that gave rise to increased activity were steric hindrance about the metal centre resulting from hindered ligands such as 2,6-dimethylpyridine, or the presence of a phosphorus donor ligand. Little correlation between palladium and platinum complexes was noted. Four complexes were selected for further in vivo study and, while none of the palladium complexes showed more than marginal activity against P388 leukæmia at doses below toxic levels, one platinum complex with a hindered metal centre did display significant antitumour activity against this model.Key words: cyclometallation, palladium, platinum, cytotoxicity, anticancer.
Dynamic Change of Energy Metabolism by Electroacupuncture Stimulation in Rats
Authors: Tseng Chia-Shun , Shen Wu-Chung , Cheng Fu-Chou , Chen Guan-Wei , Li Tsai-Chung , Hsieh Ching-Liang
Published: September 2005

The electrical stimulation of meridian points in rats inhibits the withdrawal reflex of the nociceptive tail. Its pain mechanisms are well-documented. Moreover, electroacupuncture (EA) at special abdominal acupoints has been shown to induce a short-term hypoglycemia effect in streptozotocin diabetic rats. The Zusanli and Zhongwan acupoints have been widely used in traditional Chinese medicine to relieve symptoms of diabetes mellitus. It is still unclear whether they can affect extracellular glucose and lactate metabolites at the cellular level. The aim of this study is to evaluate these effects using a rat model for the analysis of extracellular neurochemicals. First, electrical stimulus of 2 ms 2 Hz square pulses (30 minutes) was applied to anesthetized intact rats ( n = 7) at the Zusanli points. One and a half hours later, a second electrical stimulus (2 Hz pulses, 30 minutes) was delivered to two of the rats at the same spot. Another two rats received a different stimulation (100 Hz pulses, 30 minutes) at the same location. In the final three rats, a second electrical stimulus of 2 Hz pulses was delivered to non-acupoints. An automated micro-blood sample collector was used to examine the glucose, pyruvate and lactate concentrations. The EA signal has an influence on the biologic process of energy metabolism by mediating dynamic extracellular neurochemical changes. The EA at limb acupoints of the lower limbs induces a decrease in glucose, an increase in lactate metabolites and a decrease in the lactate/glucose ratio. Moreover, the increased lactate/glucose ratio suggests that the cell has an increased anaerobic glucose metabolism.