bluuebunny/crossref_metadata_2025 huggingface dataset:
Optimization of a blood pool contrast agent injection protocol for MR angiography
Authors: Robert Philippe , Violas Xavier , Santus Robin , Le Bihan Denis , Corot Claire
Published: April 2005

Purpose

To design an ideal first‐pass profile for MR angiography (MRA) by optimizing a multiphasic injection protocol based on two experimental animal models.

Materials and Methods

An equivalent contrast‐enhanced (CE) MRA injection protocol was developed with controlled injection modalities (injection rate, volume, and dose) in rabbits and pigs. P792, a blood pool contrast agent, was injected in 17 male New Zealand rabbits and five farm pigs with variable injection schemes (mono‐ and multiphasic). From the gadolinium (Gd) blood concentration data, a simulation of an MR acquisition was performed to evaluate the impact of such an injection protocol on MR arterial signal and to select the best injection protocol.

Results

An empirical relationship between the arterial peak concentration and the injection parameters was found in the rabbits and pigs, allowing precise prediction of the first‐pass profile. Of the four injection scheme strategies tested (standard bolus and bi‐, tri‐, and multiphasic injection protocols), the multiphasic “ramp” injection protocol provided the most optimal contrast agent pharmacokinetics with a durable plateau of concentration.

Conclusion

Ramp injection protocol provides an optimized first‐pass profile for CE‐MRA. J. Magn. Reson. Imaging 2005;21:611–619. © 2005 Wiley‐Liss, Inc.
Human T‐cell lymphotropic virus antibody prevalence in HIV‐1‐infected individuals attending a sexual health clinic in South‐East London
Authors: Cooke Fiona J. , Geretti Anna Maria , Zuckerman Mark
Published: April 2005

Human immunodeficiency virus (HIV) and human T‐cell lymphotropic virus (HTLV) are both retroviruses with similar routes of transmission. A number of reports suggest variable clinical outcomes in HIV and HTLV co‐infected individuals. There is no published information regarding the prevalence of HIV and HTLV co‐infection in the UK. We therefore carried out an unlinked anonymised retrospective study to investigate the prevalence of HTLV co‐infection in HIV infected patients attending a sexual health clinic in South‐East London. We identified sera from 777 HIV‐1 positive adults (504 male, 273 female) who had attended our sexual health clinic between January 2000 and March 2001. Serum samples stored at −20°C were initially tested by HTLV‐1 and HTLV‐2 antibody enzyme‐linked immunoassay (EIA). An immunoblot assay was carried out on reactive samples to discriminate between viral subtypes. Samples with indeterminate results were also analyzed by Western blot. The prevalence of HTLV antibody was 0.8% (five patients with HTLV‐1 and one with HTLV‐2). Four of the HTLV‐1 co‐infected patients were females born abroad, of Black African or Caribbean origin. The other HTLV‐1‐infected patient was a male in the Black Other ethnic group born in the UK, demonstrating that transmission may occur outside recognized areas of high endemicity. The HTLV‐2 co‐infected individual was a White male born in Italy, and was likely to have been infected through intravenous drug use. The results suggest HTLV antibody screening should be considered in the local HIV infected population of south London. J. Med. Virol. 76:143–145, 2005. © 2005 Wiley‐Liss, Inc.
Distribution of genotype/subtype and mutational spectra of the surface gene of hepatitis B virus circulating in Hanoi, Vietnam
Authors: Thanh Thuy Le Thi , Ryo Haruko , Van Phung Le , Furitsu Katsumi , Nomura Taisei
Published: April 2005

In order to ascertain the molecular epidemiological features and mutational spectra of hepatitis B virus (HBV) in Hanoi, Vietnam, direct sequencing of the 219‐nucleotide fragment of the surface (S) gene of HBV from the sera of 40 patients mostly with chronic hepatitis were carried out. The samples were classified into genotypes by phylogenetic and genotype‐specific analysis, and subtypes by the deduced amino acid sequences. The results showed that genotype B with ayw1 was predominant genotype/subtype (63%), followed by genotype C with adr (18%). The quasi‐species nature of the HBV in the sera was observed in 24 of 40 samples examined. One sample (HN109) showed mixture of genotypes B and C. Among 26 amino acid substitutions, 16 were the variants and the remainders were mutations. In the “a” determinant region, three mutations with methionine to leucine (L) changes at the 133 amino acid residue were in the first loop and no mutations were in the second loop. A new mutation, threonine to methionine at 126 amino acid residue, was observed in one sample. In conclusion, the analysis of the S gene region of HBV showed that in Hanoi, genotype B with ayw1 was prevalent and the quasi‐species nature of HBV was also common. J. Med. Virol. 76:161–169, 2005. © 2005 Wiley‐Liss, Inc.
Molecular epidemiology of hepatitis B virus in Spain: Identification of viral genotypes and prediction of antigenic subtypes by limited sequencing
Authors: Echevarría José M. , Avellón Ana , Magnius Lars O.
Published: April 2005

The hepatitis B virus (HBV) genotypes were studied by a line probe assay (LiPA) and by direct sequencing of a 339 nucleotide fragment from the S region of the viral genome in samples from 269 carriers living in Spain, either native to Spain (231) or immigrants from Africa, Asia, and Eastern Europe (38). The sequences were also used to predict the HBV surface antigen (HBsAg) subtype on the basis of the amino acids specified at selected positions of the HBsAg molecule. Agreement between the two genotyping methods was found in most cases (98.1%) and a HBV genotype could be assigned to all samples. The viral groups D/ayw2 (30.1%), D/ayw3 (28.6%), and A/adw2 (21.2%) were prevalent, with an additional participation of the groups D/ayw4 (4.8%), F/adw4q− (1.9%), A/ayw1 (1.9%), and D/adw3 (0.7%), all of them present among the autochthonous carriers. Strains from genotypes B and C were found exclusively among Chinese immigrants. Genotype E strains were found in immigrants from Central Africa and in one patient native of Spain. Point mutations leading to amino acid changes of residues involved in the expression of the HBsAg subtype determinants were found in 12 samples (4.5%). Some mutations would predict the putative novel genotype‐subtype associations A/adw4q+, A/ayr, D/ayr, and E/ayw1, while others would suggest the loss of subtype‐specific determinants. The finding of HBV strains characteristic for Africa among the autochthonous carriers confirms the emergence of African HBV strains in Spain. J. Med. Virol. 76:176–184, 2005. © 2005 Wiley‐Liss, Inc.
Hepatitis C virus infection in cameroon: A cohort‐effect
Authors: Nerrienet Eric , Pouillot Régis , Lachenal Guillaume , Njouom Richard , Mfoupouendoun Jermie , Bilong Catherine , Mauclere Philippe , Pasquier Christophe , Ayouba Ahidjo
Published: April 2005

A hepatitis C virus (HCV) serological study conducted in 2003 on 1,434 individuals in Yaounde and other HCV seroepidemiological studies on 2,066 sera sampled between 1993 and 1997 in four geographically distinct rural areas (Ntem, Mekas, Yokadouma, and Nditam) in Cameroon, are described. Two patterns of HCV seroprevalence were observed. The first pattern, represented by Nditam and Yokadouma populations, showed low HCV seroprevalence rates (2.9% and 3.3%, respectively) increasing moderately with age (9.0% and 16.7% after age 50). The second pattern showed high seroprevalence rates (6.9% for Yaounde, 14.4% and 16.7% for Ntem and Mekas, respectively). These rates increased dramatically with age (32.8%–49.5% after age 50). The age‐specific anti‐HCV prevalence curve of the 1993 Mekas survey paralleled those of the 1997 Ntem and 2003 Yaounde surveys. Using the year of birth as the x‐axis, the three curves closely matched each other. This clearly indicates a cohort effect for which the seroprevalence trends are clearly related with the year of birth, rather than the age. The highest prevalence was observed among people born around 1940. J. Med. Virol. 76:208–214, 2005. © 2005 Wiley‐Liss, Inc.
Detection of human herpesvirus 7 DNA in peripheral blood reflects mainly CD4+ cell count in patients infected with HIV
Authors: Boutolleau David , Bonduelle Olivia , Sabard Amélie , Devers Laure , Agut Henri , Gautheret‐Dejean Agnès
Published: April 2005

The opportunistic behavior and the potential interactions of human herpesvirus 7 (HHV‐7) with human immunodeficiency virus (HIV)‐1 in HIV‐1‐infected patients were investigated in comparison with HHV‐6, another human roseolovirus. Roseolovirus DNAs were detected and quantified in peripheral blood mononuclear cells (PBMCs) from 198 HIV‐seronegative healthy blood donors, 38 HIV‐1‐infected patients classified as long‐term non‐progressors, and 99 HIV‐1‐infected patients classified as progressors. The rate of HHV‐7 DNA detection was higher in healthy donors (78%) than in long‐term non‐progressors (47%; P = 0.0003) or in progressors (52%; P < 0.0001). HHV‐7 cell load was higher in healthy donors (median: 212 EqCop/106 PBMCs) and in long‐term non‐progressors (median: 105 EqCop/106 PBMCs) than in progressors (median: 48 EqCop/106 PBMCs; P < 0.0001 and P = 0.015, respectively). Among progressors, HHV‐7 detection was correlated positively with the CD4+ T‐lymphocyte count (P = 0.028). Neither HHV‐7 detection rate nor cell load was correlated with the HIV‐1 plasma load. As a whole, HHV‐6 detection rate and cell load were lower than the HHV‐7 counterparts, albeit exhibiting similar differences between healthy donors, long‐term non‐progressors, and progressors. In conclusion, HHV‐7 infection does not appear to be stimulated by HIV‐1 infection, nor interact with it. Rather, HHV‐7 detection rate and cell load reflect CD4+ T‐lymphocyte count, with higher values in healthy donors and long‐term non‐progressors than in progressors. J. Med. Virol. 76:223–228, 2005. © 2005 Wiley‐Liss, Inc.
HFRS causing hantaviruses do not induce apoptosis in confluent Vero E6 and A‐549 cells
Authors: Hardestam Jonas , Klingström Jonas , Mattsson Karin , Lundkvist Åke
Published: April 2005

Hantaviruses are known to cause little or no cytopathic effect in vitro, but have been suggested to cause apoptosis. To determine whether different hantaviruses would induce apoptosis to varying degrees, confluent Vero E6 cells were infected with the hemorrhagic fever with renal syndrome (HFRS) causing viruses Hantaan, Dobrava, Saaremaa, and Puumala. However, no difference was found in the percentage of adherent cells, or of cells with condensed nuclei, between non‐infected and virus‐infected cells at 3, 6, 9, or 12 days after infection. Furthermore, no differences in the percentage of cells with inter‐nucleosomal cleavage of DNA between uninfected and Hantaan infected cells could be detected using the TUNEL assay. Possibly, slightly more apoptotic cells, but never more than 5%, were detected after Hantaan infection of non‐confluent cells as compared to the negative control. Earlier reported results that Tula hantavirus induces significant apoptosis on Vero E6 cells were also verified, suggesting that non‐pathogenic hantaviruses might differ from HFRS‐causing strains regarding induction of apoptosis. In conclusion, the results indicated that the HFRS‐causing hantaviruses might induce a very low level of apoptosis in dividing cells, but not at all in confluent cells. J. Med. Virol. 76:234–240, 2005. © 2005 Wiley‐Liss, Inc.
Comparison of affinity chromatography and adsorption to vaccinia virus recombinant infected cells for depletion of antibodies directed against respiratory syncytial virus glycoproteins present in a human immunoglobulin preparation
Authors: Sastre Patricia , Melero José A. , García‐Barreno Blanca , Palomo Concepción
Published: April 2005

Antibodies directed against human respiratory syncytial virus (HRSV) glycoproteins were depleted from a commercial immunoglobulin preparation (RespiGam) by two different methods. The first method consisted of repeated adsorption of RespiGam to Sepharose beads with covalently bound soluble forms of the two major viral glycoproteins (F or G). The second method consisted of adsorption of immunoglobulins to live cells expressing F or G glycoproteins on their surfaces after infection with vaccinia virus recombinants. While the first method removed efficiently antibodies that reacted with F and/or G glycoproteins by ELISA, it was inefficient in the elimination of anti‐HRSV neutralizing antibodies. In contrast, the second method removed efficiently anti‐HRSV antibodies that both reacted by ELISA and neutralized virus infectivity. These results confirm that human neutralizing antibodies are directed exclusively against HRSV F and G glycoproteins, and, they raise the possibility that F and G glycoproteins inserted into cell membranes differ antigenically from their soluble forms linked covalently to Sepharose beads. J. Med. Virol. 76:248–255, 2005. © 2005 Wiley‐Liss, Inc.
Preliminary study on the efficacy and safety of lamivudine and interferon α therapy in decreasing serum HBV DNA level in HBV positive transgenic mice during pregnancy
Authors: Li Duan , Xu De‐Zhong , Choi Bernard C.K. , Men Ke , Zhang Jing‐Xia , Lei Xiao‐Ying , Yan Yong‐Ping
Published: April 2005

Previous studies reported that the HBV DNA level in maternal serum is an important risk factor for intrauterine infection. Two antiviral drugs, lamivudine (3TC) and interferon α (IFNα), are used extensively clinically to reduce maternal HBV DNA level, However, because of a lack of evidence on the efficacy and safety of these drugs during pregnancy, they are categorized as grade C which prevents their use during pregnancy. This study provides new data on the efficacy and safety of lamivudine and IFNα in HBV positive transgenic pregnant mice. In this study, transgenic mice with high titers of hepatitis B virus (HBV) were employed to study the antiviral effects of 3TC and IFNα during different gestation periods. The study also examined changes in several serological HBV markers, the effects of perinatal exposure to antiviral drugs on the mother and offspring, drug efficacy in reducing the level of HBV DNA in maternal blood, and the safety to both the mother and offspring. The main conclusion of the study is that a significant decrease in HBV DNA level can be obtained after treatment with lamivudine but not with IFNα. No adverse effects were observed in the maternal mice and the offsprings. This finding may provide a rationale for the potential use of lamivudine for the treatment of pregnant women as a safe and effective measure to reduce the level of maternal viremia. J. Med. Virol. 76:203–207, 2005. © 2005 Wiley‐Liss, Inc.
Isotope‐edited UV Raman spectroscopy of protein–DNA interactions: binding modes of cyclic AMP receptor protein to a natural DNA recognition site
Authors: Toyama Akira , Matsubuchi Akiko , Fujimoto Naoko , Takeuchi Hideo
Published: April 2005

Isotope‐edited UV Raman spectroscopy was applied to the study of the binding mode of cyclic AMP (cAMP) receptor protein (CRP) to a 22‐mer oligonucleotide (LacDNA) representing the primary CRP binding site of the E. coli lac promoter. LacDNA contains four guanine residues in the consensus pentamer regions (G5 and G7 on the sense strand and G5′ and G7′ on the anti‐sense strand) and they were individually labeled with deuterium at C(8) on the guanine ring. In the UV (251 nm) Raman difference spectrum between unlabeled and C(8)‐D‐labeled LacDNA, a sharp positive/negative peak pair appeared at ∼1490/1465 cm−1, which was assigned to a guanine ring vibration (ν6/ν6′) sensitive to the hydrogen bonding state at C(6)O. CRP is a dimeric protein and forms two complexes with the cofactor cAMP, i.e. half‐filled CRP–(cAMP)1 and fully liganded CRP–(cAMP)2. The ν6/ν6′ wavenumbers measured in the presence of CRP showed that CRP–(cAMP)1 binds to G5 and G5′ in a symmetric manner, whereas CRP–(cAMP)2 exhibits an additional binding to G7. Since the base sequence of LacDNA and the structure of CRP–(cAMP)1 are both asymmetric, the symmetric LacDNA–CRP–(cAMP)1 interaction suggests that CRP–(cAMP)1, which is considered to be dominant under physiological conditions, has a conformational flexibility to conform to structural asymmetry of natural DNA sequences. In contrast, the symmetric complex CRP–(cAMP)2 binds to LacDNA asymmetrically, suggesting a decreased flexibility of CRP in the fully liganded form. Isotope‐edited UV Raman spectroscopy provides unique information on the DNA recognition by CRP. Copyright © 2005 John Wiley & Sons, Ltd.
Hydrogen bonding dynamics and two‐dimensional vibrational spectroscopy: N‐methylacetamide in liquid methanol
Authors: Kwac Kijeong , Cho Minhaeng
Published: April 2005

The distribution of the fluctuating amide I mode frequency of N‐methylacetamide (NMA)–methanol solution at room temperature was recently found to be non‐Gaussian and can be decomposed into two Gaussians that are associated with two different solvation structures. In the present paper we discuss the temperature dependences of hydrogen bonding dynamics and their influences on one‐ and two‐dimensional vibrational spectra by carrying out molecular dynamics simulations of the same solution at five temperatures from 230 to 310 K. The radial distributions reveal the detailed solvent configuration around the NMA. The two‐species model where conformational transitions between the two distinct solvation structures are treated as a reversible reaction and the Onsager regression hypothesis was used to estimate the hydrogen bond association and dissociation rates and to study thermodynamic properties. By using the time evolution of the amide I mode frequency fluctuation, both IR absorption and two‐dimensional IR photon echo spectra were numerically simulated and compared with approximate two‐species model results. An approximation method that can be used to extract kinetic information of the hydrogen bonding dynamics from the spectra is briefly discussed. Copyright © 2005 John Wiley & Sons, Ltd.
Resonance Raman characterization of a high‐spin six‐coordinate iron(III) intermediate in metmyoglobin–azido complex formation trapped by microsecond freeze‐hyperquenching (MHQ)
Authors: Lu Shen , Wiertz Frank G. M. , de Vries Simon , Moënne‐Loccoz Pierre
Published: April 2005

The reaction of metmyoglobin with azide was used to characterize a novel freeze‐quench instrument with a mixing and freezing time resolution in the microsecond time range. Samples quenched within 95 and 245 µs after mixing of metmyoglobin with 1 M azide were characterized by low‐temperature UV–visible and resonance Raman spectroscopy with excitation into the Soret band. Comparison of these data with control samples where azide is absent or metmyoglobin is preincubated with azide demonstrates the formation of an intermediate complex in the first 95 µs after mixing that has fully decayed after 245 µs. Porphyrin skeletal modes displayed by this transient species identify it as a six‐coordinate high‐spin species. Minor low‐spin components are also observed and suggest that the hexacoordinated intermediate exists as a spin equilibrium. This preliminary study demonstrates the feasibility of this approach to detect new intermediates and to characterize early reaction intermediates in other metalloproteins. Copyright © 2005 John Wiley & Sons, Ltd.
Structure and dynamics of biomolecules probed by Raman spectroscopy
Authors: Schweitzer‐Stenner Reinhard
Published: April 2005

Raman spectroscopy is still a suitable and prominent method for probing the relationship between structure, dynamics and function of biomolecules. In this context, resonance Raman spectroscopy is of particular relevance since it allows the site‐specific investigation of chromophores (aromatic amino acid residues, nucleotides, heme groups) which are directly involved in mechanisms pivotal for the function of the respective molecules. Time‐resolved spectroscopy (Raman and IR) is utilized to explore, e.g., structural changes in heme proteins upon ligand photolysis. Conventional visible Raman is still a useful tool to explore peptides and proteins and to determine the orientation of oriented nucleic acid fibres. Copyright © 2005 John Wiley & Sons, Ltd.
Raman evidence for product binding to the enzyme W137F 4‐chlorobenzoyl‐CoA dehalogenase in two conformational states
Authors: Dong Jian , Luo Lusong , Dunaway‐Mariano Debra , Carey Paul R.
Published: April 2005

The enzyme 4‐chlorobenzoyl‐CoA dehalogenase catalyzes the hydrolytic dehalogenation of 4‐chlorobenzoyl‐CoA (4‐CBA‐CoA) to yield 4‐hydroxybenzoyl‐CoA (4‐HBA‐CoA). Part of the catalytic mechanism involves interaction between an active site side‐chain, from Asp145, with the 4‐position of the benzoyl moiety. For the complex consisting of product 4‐HBA‐CoA in the active site the interaction between Asp145 and the 4‐OH group helps produce a major rearrangement in the benzoyl's π‐electron system with the system becoming highly polarized. This leads to a large red shift in the benzoyl λmax, from 260 to 370 nm, and radical changes in the Raman spectrum. In addition to the Asp145‐4‐OH interaction, the aspartate side‐chain is held in place by a hydrogen bond to the indole side‐chain of Trp137. We explored the consequences of removing this hydrogen bonding interaction by using protein engineering techniques to replace Trp137 by Phe, Ala or His. For 4‐HBA‐CoA binding to Trp137Phe dehalogenase there is spectroscopic evidence for two conformational populations for bound product. One species (highly polarized) has a λmax near 375 nm and intense Raman bands at 1550, 1520 and 658 cm−1, whereas the second species (moderately polarized) has a λmax near 330 nm and an intense Raman mode at 1575 cm−1. Raman data collected between 6 and 34 °C demonstrate population changes with the highly polarized species having the highest thermodynamic stability. Copyright © 2005 John Wiley & Sons, Ltd.
The effect of land management on carbon and nitrogen status in plants and soils of alpine meadows on the Tibetan plateau
Authors: Wang W. Y. , Wang Q. J. , Wang Ch. Y. , Shi H. L. , Li Y. , Wang G.
Published: April 2005

Large‐scale grassland rehabilitation has been carried out on the severely degraded lands of the Tibetan plateau. The grasslands created provide a useful model for evaluating the recovery of ecosystem properties. The purposes of this research were: (1) to examine the relative influence of various rehabilitation practices on carbon and nitrogen in plants and soils in early secondary succession; and (2) to evaluate the degree to which severely degraded grassland altered plant and soil properties relative to the non‐disturbed native community. The results showed: (1) The aboveground tissue C and N content in the control were 105·97 g m−2 and 3·356 g m−2, respectively. The aboveground tissue C content in the mixed seed treatment, the single seed treatment, the natural recovery treatment and the severely degraded treatment was 137 per cent, 98 per cent, 49 per cent and 38 per cent, respectively, of that in the control. The corresponding aboveground tissue N content was 109 per cent, 84 per cent, 60 per cent and 47 per cent, respectively, of that in the control. (2) Root C and N content in 0–20 cm depths of the control had an average 1606 g m−2 and 30·36 g m−2, respectively. Root C and N content in the rehabilitation treatments were in the range of 26–36 per cent and 35–53 per cent, while those in the severely degraded treatment were only 17 per cent and 26 per cent of that in the control. (3) In the control the average soil C and N content at 0–20 cm was 11 307 g m−2 and 846 g m−2, respectively. Soil C content in the uppermost 20 cm in the seeded treatments, the natural recovery treatment and the severely degraded treatment was 67 per cent, 73 per cent and 57 per cent, respectively, while soil N content in the uppermost 20 cm was 72 per cent, 82 per cent and 79 per cent, respectively, of that in the control.

The severely degraded land was a major C source. Restoring the severely degraded lands to perennial vegetation was an alternative approach to sequestering C in former degraded systems. N was a limiting factor in seeding grassland. It is necessary for sustainable utilization of seeding grassland to supply extra N fertilizer to the soil or to add legume species into the seed mix. Copyright © 2005 John Wiley & Sons, Ltd.
Influence of land management on soil nutrients and microbial biomass in the central loess plateau, northwest China
Authors: Jia G.‐M. , Cao J. , Wang G.
Published: April 2005

Loss of soil organic matter under cropping systems is often considered one of the most serious forms of agriculturally induced soil degradation. Therefore, understanding how to improve or maintain soil fertility is of importance for sustainable systems of agriculture. This study deals with the effects of succession fallow and fertilization combined with crop rotation on the chemical properties and microbial biomass of soil in the central Loess Plateau, China. In order to create a more uniform experimental environment and avoid the influence of different crop residues, wheat/potato (W/P) rotation was selected as a fertilization treatment. The results showed that with increasing fallow time organic carbon (Corg) and total nitrogen (TN) slightly increased, microbial biomass carbon (MBC) and MBC/Corg gradually decreased, and microbial biomass nitrogen (MBN) remained unchanged. However, only MBC/Corg among all the microbial parameters measured showed significant differences at various stages of fallow. Although there was a decrease in organic carbon and total nitrogen in the fertilized plots, MBC was not significantly different in the various fallow and fertilized plots except for one‐year‐old fallows, which had the highest MBC. MBN, MBC/Corg and MBN/TN in fertilized plots were higher than for plots at different stages of fallow. Fertilization can increase organic carbon, total nitrogen, MBC and MBN content (compared to the control). It was concluded that appropriate land management, such as fertilization combined with crop rotation and reducing one‐year‐old fallow, would be useful ways to improve or maintain soil fertility. Copyright © 2005 John Wiley & Sons, Ltd.
Knowing and doing: How to put learning where the work is
Authors: Bordonaro Frank P.
Published: April 2005

The idea that knowing and doing should be tightly linked may seem like a management no‐brainer. But progress in putting learning more directly on the path of work has been slowed by conventional thinking. How can leaders move learning to the places and people where it can most powerfully further the strategy of the company? First, they must put aside old habits and form a new perspective about where the most important learning takes place.
Modeling of Ethylene‐Norbornene Copolymer Microstructure in Solution Polymerization with Homogeneous Metallocene Catalysts
Authors: Park Seung Young , Choi Kyu Yong
Published: April 2005

Summary: The microstructure of ethylene‐norbornene copolymer produced in solution polymerization is analyzed through kinetic modeling and experiments using homogeneous rac‐Et(1‐indenyl)2ZrCl2/methylaluminoxane catalyst in toluene at 70 °C. The sequence distribution function and average chain length equations are derived for terminal model and penultimate model. The model simulations show that both models provide similar predictions of average copolymer composition, especially at low norbornene concentration in the copolymer. However, at higher norbornene concentrations the penultimate model yields much better predictions of norbornene sequence length distribution than the terminal model. The terminal model has been inadequate in describing the copolymerization rate, whereas the penultimate model yields excellent predictions of rate behavior. The model calculations also indicate that at norbornene concentration in the copolymer larger than about 10 mol‐%, the maximum ethylene block length is smaller than 70, prohibiting the formation of crystalline copolymer.

Ethylene sequence distribution curves at different mol‐% of norbornene in copolymer.

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Ethylene sequence distribution curves at different mol‐% of norbornene in copolymer.
Comparison of Gas and Liquid Propylene Polymerization Technique – Hydrogen Effect on Thermal, Rheological, and Morphological Properties of PP
Authors: Stern Claudia , Frick Achim Robert , Pater Joachim Theodorus Maria , Weickert Günter
Published: April 2005

Summary: A comparison of PP qualities, which are produced with two different polymerization techniques–gas phase(GP) and liquid pool (LP)–under precise control of the polymerization temperature (70 °C) and pressure (GP = 25 bar, LP < 60 bar) using identical Ziegler‐Natta catalyst (TiCl4/phthalate/MgCl2 + TEA/silane), is presented. A series of homopolymer PP in a wide MW range from 100 000 to 1 600 000 g · mol−1 was polymerized. During polymerization all samples were characterized exactly by their Rp‐profil. The effect of hydrogen on the initial reaction rate and on MW and MWD was analyzed on the basis of this so‐called kinetic fingerprint. The results showed that the polymerization rate reached a maximum for LP, of about 150 kg · gcat−1 · h−1, in contrast to GP with a maximum of Rp,0 = 45 kg · gcat−1 · h−1. Analysis was carried out by means of GPC, SEM, DSC, platte‐platte rheometer, and WAXS. The results first showed that the MWD of LP PP is narrower (PD ∼ 6.8) than for the GP PP (PD ∼ 8), polymerized in two steps. An SEM study of the powder particle shows the typical dent surface morphology of polymers using Ziegler‐Natta catalysts for polymerization. WAXS and DSC analysis demonstrated that almost only the α‐modification of crystalline structure exists and that the crystallinity becomes considerably higher after solidification from melt. Furthermore, it was found that the crystallite size distribution depends on the polymerization technique. Rheological studies indicate that GP PP behaves more elastically. To summarize, it is shown that PP produced with the LP polymerization technique is more homogenous and of high quality.

Particle geometry of gas phase and liquid pool polymerized PP powder observed by SEM (PP‐L0).

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Particle geometry of gas phase and liquid pool polymerized PP powder observed by SEM (PP‐L0).
A Unified Model for the Mixing of Non‐Newtonian Fluids in the Laminar, Transition, and Turbulent Region
Authors: Wassmer Karl‐Heinz , Hungenberg Klaus‐Dieter
Published: April 2005

Summary: Non‐Newtonian fluid behavior has significant influence on quantities in chemical engineering like power input, mixing time, heat transfer etc. In the laminar flow region, the concept of effective viscosity by Metzner and Otto is well established. In the transition region between laminar and turbulent flow, the existing concepts use three and even more empirical parameters to determine the specific power input. Here, a unified and general but simple approach is introduced to calculate the power input for shear thinning fluids over the whole flow region using just one empirical parameter. The Metzner‐Otto relation is obtained as a limiting case for the laminar region. The empirical parameter of the new approach is related to the Metzner‐Otto constant. The concept is validated for eight different stirrer systems. Mixing time and maximum shear rate and heat transfer can also be calculated using this approach. The new concept presented should also be applicable for other apparatuses, e.g., static mixers.

Comparison of experimental data and a curve calculated according to the new method (solid line).

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Comparison of experimental data and a curve calculated according to the new method (solid line).
Identifying and distinguishing cases of parkinsonism and Parkinson's disease using ICD‐9 CM codes and pharmacy data
Authors: Swarztrauber Kari , Anau Jane , Peters Dawn
Published: April 2005

Administrative databases have the potential to assess quality and cost of care for parkinsonism and Parkinson's disease. However, the validity of findings is limited by our understanding of how cases are identified. Patient records listing International Classification of Diseases, Version 9, Clinical Modification (ICD‐9 CM) codes for parkinsonism (n = 2,076) and dopaminergic medications (n = 2,798) were pulled from fiscal years 1999 to 2001 for patients in the Pacific Northwest Veterans Administration. Samples of these records (n = 397) and records without these ICD‐9 CM codes (n = 500) were reviewed, and clinical data were extracted. The accuracy of administrative data to identify and distinguish between Parkinson's disease and parkinsonism was calculated. A total of 37.9% of parkinsonism cases were detected using pharmacy data and ICD‐9 CM codes compared to 18.7% by using ICD‐9 CM codes alone. The ICD‐9 CM code for paralysis agitans (332.0) did not distinguish between probable Parkinson's disease and other causes of parkinsonism, whereas the ICD‐9 CM code for degenerative basal ganglia disorder (333.0) predicted having secondary parkinsonism (odds ratio [OR] = 5.0) as well as dopa‐responsiveness in patients without secondary parkinsonism (OR = 4.5). Administrative data are limited in the ability to identify parkinsonism. The ICD‐9 CM code, 332.0, which is generally considered the code to identify Parkinson's disease, did not distinguish between parkinsonism and Parkinson's disease. © 2005 Movement Disorder Society
Association between male gender and pediatric essential tremor
Authors: Louis Elan D. , Fernandez‐Alvarez Emilio , Dure Leon S. , Frucht Steven , Ford Blair
Published: April 2005

Approximately 5% of new essential tremor (ET) cases arise during childhood. The goal of the current report was to examine the possible association between male gender and pediatric ET, using data from 95 pediatric ET cases seen at three medical centers (two in the United States and one in Spain). The odds of ET in our sample of cases were threefold higher in boys compared to girls. Whether this association between male gender and pediatric ET represents a selection bias or a true gender‐mediated biological difference in disease expression is not known, although some data support the latter possibility. © 2005 Movement Disorder Society
Anticancer multidrug resistance mediated by MRP1: Recent advances in the discovery of reversal agents
Authors: Boumendjel Ahcène , Baubichon‐Cortay Hélène , Trompier Doriane , Perrotton Thomas , Di Pietro Attilio
Published: April 2005

Multidrug resistance protein 1 (MRP1) belongs to the ATP‐binding cassette (ABC) transporter family. It is able to transport a broad range of anticancer drugs through cellular membranes, thus limiting their antiproliferative action. Since its discovery in 1992, MRP1 has been the most studied among MRP proteins, which now count nine members. Besides the biological work, which targets structure elucidation, binding sites location, and mode of action, most efforts have been focused on finding molecules which act as MRP1 inhibitors. In this review, we attempt to summarize and highlight studies dealing with modulators of MRP1‐mediated multidrug resistance (MDR), which have been accomplished in the last 5 years. The reported MRP1 inhibitors are discussed according to their chemical class. Finally, we try to bring information on structure–activity relationship (SAR) aspects and how modulators might interact with MRP1. This study may facilitate the rational design of future modulators of MDR. © 2005 Wiley Periodicals, Inc.
Kinetic study of the effect of poly(phenyl sulfone) on the curing of an epoxy/amine resin by conventional and by temperature‐modulated differential scanning calorimetry
Authors: Cedeño Asdrúbal J , Vázquez‐Torres Humberto
Published: April 2005

Kinetic studies of the curing reaction of semi‐interpenetrating polymer networks (semi‐IPNs) based on diglycidyl ether of bisphenol‐A (DGEBA) and 4,4′‐diaminodiphenylmethane (DDM), containing poly(phenyl sulfone) (PPSU), were carried out using differential scanning calorimetry (DSC) and temperature‐modulated DSC (TMDSC), under both isothermal and dynamic conditions. The curing kinetics is discussed in the framework of three kinetic models: the Kissinger and the Flynn–Wall–Ozawa models, and the autocatalytic model developed by Kamal. To describe the cured reaction in its latter stage, we used the semi‐empirical relationship proposed by Chern and Poehlein to consider the influence of diffusion on reaction rate. The cure mechanism for the system studied remained broadly autocatalytic regardless of PPSU content, and it became far more diffusion controlled at higher PPSU content and lower cure temperatures. The vitrification time of the resins was obtained with TMDSC by following the changes on the complex modulus of heat capacity, $|C_{\rm {P}}^{*}|$, and exhibited a strong dependence on the PPSU content in the semi‐IPN systems. Copyright © 2005 Society of Chemical Industry
Synthesis and characterization of stable blue light‐emitting poly(spirobifluorene) derivatives containing alkoxy group
Authors: Lee Ki‐Suk , Kim Yun‐Hi , Lee Yongkyun , Jang Jin , Kwon Soon‐Ki
Published: April 2005

Polymers containing alkoxy‐substituted spirobifluorene have been prepared from nickel(0)‐mediated coupling or palladium‐catalyzed Suzuki coupling. The polymers were characterized using various spectroscopies, such as 1H‐NMR, FT‐IR, and elemental analysis. The high glass transition temperature and high decomposition temperature suggested that the resulting polymers possessed a high thermal stability. The obtained polymers possessed weight average molecular weight of 4500–33,000 with polydispersity index of 1.1–1.9 and good solubility. The low onsets of the oxidation potential suggested that the polymers containing alkoxy substituted spirobifluorene possessed a good hole injection property. The photoluminescence and electroluminescence of the polymers containing alkoxy substituted spirobifluorene showed stable blue color by suppressing the excimer formation due to intermolecular interaction. © 2005 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 43: 2316–2324, 2005
Density functional theory simulations of two‐dimensional infrared spectra for hydrogen‐bonded acetic acid dimers
Authors: Dreyer Jens
Published: April 2005

Two‐dimensional coherent infrared spectra are simulated based on density functional theory calculations to analyze vibrational couplings in hydrogen‐bonded acetic acid dimers. Anharmonic sixth‐order force fields covering up to three‐body interactions are calculated for up to 11 normal modes. Three mechanisms for vibrational coupling within the two intermolecular hydrogen bonds are considered: anharmonic coupling of the high‐frequency OH stretching mode to low‐frequency modes, Fermi resonance coupling the of OH stretching mode to fingerprint mode combination tones, and a combination of both. Predicted coherent two‐dimensional infrared spectra show distinct signatures for the different coupling mechanisms. © 2005 Wiley Periodicals, Inc. Int J Quantum Chem, 2005
A generalized stock control formulation for stock management problems involving composite delays and secondary stocks
Authors: Yasarcan Hakan , Barlas Yaman
Published: April 2005

It is well established in the system dynamics literature that if the stock management formulation ignores the supply line delay, the behavior of a system can be highly oscillatory. But there are no general decision rules to handle other types of delays in stock management systems, such as information delays in decision processing and delays implicit in controlling a primary stock indirectly via a secondary stock. In this research, it is first shown that the consequence of ignoring information delays or ignoring the delays implicit in secondary stock control is equivalent to ignoring the supply line delay in the standard case: large oscillations. Next, the notion of “virtual supply line” is introduced and a generalized stock control heuristic that does take into account these indirect or composite delays is derived; it is shown that the result is a stabilized dynamic behavior. Finally, the decision heuristic is implemented on an example involving all three types of delays, demonstrating the “generic” nature of the proposed formulation structure. The combined result is a significant improvement in the stability of the system, when compared with the standard formulation that considers the supply line delays only. It is also shown that the stability of the results is quite insensitive to even large errors in parameter estimates. The proposed policy is compared with some other standard stabilizing policies used in system dynamics and it is shown that the proposed policy can be conveniently combined with such policies to yield superb stability results. Finally some implementation issues and potential solutions are discussed. Copyright © 2005 John Wiley & Sons, Ltd.
Synthesis, Crystal Structure, and Vibrational Spectra of Ca4P6O19 (Trömelite) ‐ a catena‐Hexaphosphate
Authors: Höppe Henning A.
Published: April 2005

The catena–hexaphosphate Ca4P6O19 (Trömelite) was obtained by the reaction of calcium oxide with H3PO3 in a tube furnace at a temperature of 900 °C and crystallizes triclinic (space group $P{\bar 1}$, Z = 2, a = 685.70(9) pm, b = 915.47(12) pm, c = 1282.25(17) pm, α = 109.602(10)°, β = 99.778(10)°, γ = 91.917(10)°, V = 743.70(17)·106 pm3). According to the powder diffraction data of Ca4P6O19 a Rietveld refinement of the lattice constants was performed; this confirmed the single–crystal data. Trömelite contains chains of six condensed corner‐sharing PO4 tetrahedra with the Ca atoms in the voids of the resulting structure. IR and Raman data of Trömelite are also presented.
Synthesis and Crystal Structure of Ammine Copper(I) Cyanamide, Cu4(NCN)2NH3
Authors: Liu Xiaohui , Müller Paul , Dronskowski Richard
Published: April 2005

Ammine copper(I) cyanamide, Cu4(NCN)2NH3, was obtained as a white powder from the reaction between CuCl and H2NCN in concentrated ammonia solution. X‐ray and neutron diffraction experiments yield the hexagonal system with space group P63mc (no. 186) and a = 5.7661(1) Å, c = 10.7817(3) Å, and Z = 2. The structure is characterized by layers of monovalent copper ions with an average Cu–Cu distance of 2.89Å, and the layers are connected through two crystallographically independent NCN2− units. While one CuI is linearly bonded to an NCN2− unit and an additional NH3 molecule, the other CuI is also linearly coordinated but by two NCN2− groups; the Cu–N bonds lie between 1.86–1.98Å. The C–N bond lengths and angles evidence both NCN2− groups as essentially linear cyanamides.
Hydroaluminierungsreaktionen mit dem sperrigen Dialkylaluminiumhydrid [(Me3Si)2HC]2Al‐H ‐ Unterdrückung von Folgereaktionen
Authors: Uhl Werner , Matar Madhat
Published: April 2005

Hydroalumination Reactions Employing the Bulky Dialkylaluminum Hydride [(Me3Si)2HC]2Al‐H ‐ Prevention of Secondary Reactions

Usually, the hydroalumination of alkynes results in secondary reactions under release of the corresponding trialkylaluminum compounds. In contrast, the monoaddition products of R2Al‐H to C≡C triple bonds [R2Al‐(R′)C=C(R″)‐H] could be isolated in high yields now by employing the bulky dialkylaluminum hydride [(Me3Si)2HC]2Al‐H (1). This is shown here by two reactions starting with a monoalkyne (Me3C‐C≡C‐C6H5) and a dialkyne (Me3C‐C≡C‐C6H4‐C≡C‐CMe3). Both products have the aluminium atoms attached to those carbon atoms of the C=C double bonds which are in the α‐position with respect to the phenyl groups. The configuration of the alkenyl groups verifies the cis‐addition of the Al‐H bonds in all cases.
Strukturchemie, thermoanalytische und schwingungsspektroskopische Untersuchungen von PbBr2 · 2 C2D6O2 und Löslichkeitsuntersuchungen von Bleibromid in kurzkettigen Polyethylenglykolen
Authors: Oldag Thorsten , Kockelmann Winfried , Keller Hans‐Lothar
Published: April 2005

Structural Chemistry, Thermo Analysis, Vibration Spectrum of PbBr2 · 2 C2D6O2 and Solubility of PbBr2 in short Chain Polyethylene Glycoles

Temperature dependent solubility data of PbBr2 in short chain polyethylene glycoles completed with X‐ray diffraction data of the deposit are discussed. Crystals of PbBr2 · 2 C2D6O2 (1,2‐Ethandiole, furthermore called ethylene glycole) have been synthesized and structurally characterized by single crystal X‐ray investigations and powder‐neutron diffraction. PbBr2 · 2 C2D6O2 crystallizes in the monoclinic space group C2/c (No. 15) with a = 10.0887(2) Å, b = 10.8580(2) Å, c = 9.0997(1) Å, β = 92.382(2)° and Z = 4 (powder‐neutron diffraction data, 193 K). The compound can be described as a rod packing. The rods are built of nearly planar [PbBr4/2] units, surrounded by one ethylene glycol perpendicular to each side of the planar units. The linkage of these rods is realized by hydrogen bonds. A detailed description of hydrogen bonding in this compound is given.
Li2TeS3 and Li2TeSe3: Preparation, Crystal Structure and Impedance Spectroscopic Characterization
Authors: Preitschaft Christian , Zabel Manfred , Pfitzner Arno
Published: April 2005

Li2TeS3 and Li2TeSe3 were synthesized by the reaction of stoichiometric amounts of Li, Te and Q (Q = S, Se) in the ratio 2 : 1 : 3. Both products are extremely air and moisture sensitive. The crystal structures were determined by single crystal X‐ray diffraction at room temperature. Red Li2TeS3 and metallic black Li2TeSe3 crystallize isotypically in the monoclinic space group P21/c (no. 14) with four formula units per unit cell and the lattice parameters: Li2TeS3: a = 5.437(1) Å, b = 11.564(1) Å, c = 7.907(1) Å, β = 91.57(1)°, V = 496.96(1) Å3; Li2TeSe3: a = 5.658(1) Å, b = 12.032(1) Å, c = 8.278(1) Å, β = 92.690(1)°, V = 562.93(1) Å3 (data at 20 °C). The atomic arrangements persist of isolated trigonal pyramidal [TeQ3]2− anions which are arranged in layers. Li is coordinated by six Q atoms from four (Li1) or five (Li2) different thiotellurate or selenidotellurate units, respectively. Impedance spectroscopic measurements in the temperature range 90 – 200 °C show that Li2TeS3 is a semiconductor with an activation energy of 0.71 eV. Li2TeSe3 is a mixed conductor with an activation energy of 0.68 eV.
A migration analysis of the rice planthopper Nilaparvata lugens from the Philippines to East Asia with three‐dimensional computer simulations
Authors: Otuka Akira , Watanabe Tomonari , Suzuki Yoshito , Matsumura Masaya , Furuno Akiko , Chino Masamichi
Published: April 2005

Migrations of the rice planthopper Nilaparvata lugens (Stål) (Delphacidae) from the Philippines to Taiwan, southern China, and southern Japan were analyzed using three‐dimensional migration simulations. The results strongly suggested that the Southeast Asian population of N. lugens mixes with the East Asian population. This highlighted the possibility that planthoppers from the Southeast Asian population, which have properties different from those in the East Asian population such as feeding of resistant rice varieties and wing polymorphism, could migrate to Japan via southern China and Taiwan. This study, therefore, emphasizes the special care that should be taken to monitor the properties of immigrants to Japan.