bluuebunny/crossref_metadata_2025 huggingface dataset:
A detailed mutagenesis study of flavivirus cross-reactive epitopes using West Nile virus-like particles
Authors: Crill Wayne D. , Trainor Nicole B. , Chang Gwong-Jen J.
Published: March 2007

Human flavivirus infections elicit virus species-specific and cross-reactive immune responses. The flavivirus envelope (E) glycoprotein is the primary antigen inducing protective immunity; however, the presence of cross-reactive antibodies in human sera creates problems for serodiagnosis. Using a West Nile virus-like particle system, we performed mutagenesis across all three E protein functional domains to identify epitope determinants for a panel of monoclonal antibodies (mAbs) raised against different flaviviruses and exhibiting diverse patterns of cross-reactivity. Residues within the highly conserved fusion peptide were the only epitope determinants identified and were important not only for broadly cross-reactive mAbs recognizing all of the medically important flavivirus serocomplexes, but also for less-broad, complex-reactive mAbs. Moreover, different substitutions at specific fusion peptide residues produced highly variable effects on antibody reactivity and virus-like particle secretion. These results support and extend the conclusion that the fusion peptide region constitutes an immunodominant epitope stimulating antibodies with diverse patterns of cross-reactivity.
Progression of prion infectivity in asymptomatic cattle after oral bovine spongiform encephalopathy challenge
Authors: Espinosa Juan Carlos , Morales Mónica , Castilla Joaquín , Rogers Mark , Torres Juan María
Published: March 2007

The presence of BSE prion infectivity in asymptomatic cattle and its tissue distribution are important concerns for both human and veterinary health and food safety. In this work, a collection of tissues from asymptomatic cattle challenged orally with BSE and culled at 20, 24, 27, 30 and 33 months have been used to inoculate intracerebrally BoPrP-Tg110 mice expressing bovine PrP to assess their infectivity. Results demonstrate that BSE infectivity in asymptomatic cattle is essentially restricted to the nervous system, Peyer's patches and tonsils, as reported previously for terminally BSE-diseased cattle. BSE infectivity was detectable in Peyer's patches and tonsils at all time points analysed, but infectivity in nervous tissues (brainstem and sciatic nerve) was only detectable after 27 months from inoculation. Infectivity in brainstem increased markedly at 33 months after inoculation. All other investigated tissues or fluids (spleen, skeletal muscle, blood and urine) revealed no detectable infectivity throughout the time course studied.
Experimental infection of macaques with human metapneumovirus induces transient protective immunity
Authors: van den Hoogen Bernadette G. , Herfst Sander , de Graaf Miranda , Sprong Leo , van Lavieren Rob , van Amerongen Geert , Yüksel Selma , Fouchier Ron A. M. , Osterhaus Albert D. M. E. , de Swart Rik L.
Published: March 2007

Human metapneumovirus (hMPV), a member of the family Paramyxoviridae, is a causative agent of acute respiratory-tract illness. Two main hMPV lineages circulate worldwide and reinfections occur frequently. It is unclear what level of protection is induced by natural hMPV infection, what the durability of this protection is and whether it differs for reinfection with homologous or heterologous viruses. Here, protective immunity in cynomolgus macaques at different time points after inoculation with molecularly cloned prototype viruses of the two main lineages of hMPV has been addressed. Animals received a homologous challenge at 4, 6 or 12 weeks after the primary infection. In addition, animals that had been inoculated three times within 10 weeks were challenged with homologous or heterologous virus 8 months later. Primary infection with 107 TCID50 resulted in virus shedding and induction of virus-neutralizing antibody responses, with higher titres against the homologous than the heterologous virus. Infections associated with virus shedding and seroconversion protected completely from homologous reinfection within 6 weeks, and partly at 12 weeks, after primary infection. Eight months later, protection had waned to virtually undetectable levels. This study demonstrates that experimental hMPV infection induces transient protective immunity.
‘2A-like’ and ‘shifty heptamer’ motifs in penaeid shrimp infectious myonecrosis virus, a monosegmented double-stranded RNA virus
Authors: Nibert Max L.
Published: March 2007

Penaeid shrimp infectious myonecrosis virus (IMNV) is a monosegmented double-stranded RNA virus that forms icosahedral virions and is tentatively assigned to the family Totiviridae. New examinations of the IMNV genome sequence revealed features not noted in the original report. These features include (i) two encoded ‘2A-like’ motifs, which are likely involved in open reading frame (ORF) 1 polyprotein ‘cleavage’; (ii) a 199 nt overlap between the end of ORF1 in frame 1 and the start of ORF2 in frame 3; and (iii) a ‘shifty heptamer’ motif and predicted RNA pseudoknot in the region of ORF1–ORF2 overlap, which probably allow ORF2 to be translated as a fusion with ORF1 by −1 ribosomal frameshifting. Features (ii) and (iii) bring the predicted ORF2 coding strategy of IMNV more in line with that of its closest phylogenetic relative, Giardia lamblia virus, as well as with that of several other members of the family Totiviridae including Saccharomyces cerevisiae virus L-A.
Adenovirus vector delivery stimulates natural killer cell recognition
Authors: Tomasec Peter , Wang Eddie C. Y. , Groh Veronika , Spies Thomas , McSharry Brian P. , Aicheler Rebecca J. , Stanton Richard J. , Wilkinson Gavin W. G.
Published: March 2007

We report that delivery of first-generation replication-deficient adenovirus (RDAd) vectors into primary human fibroblasts is associated with the induction of natural killer (NK) cell-mediated cytolysis in vitro. RDAd vector delivery induced cytolysis by a range of NK cell populations including the NK cell clone NKL, primary polyclonal NK lines and a proportion of NK clones (36 %) in autologous HLA-matched assays. Adenovirus-induced cytolysis was inhibited by antibody blocking of the NK-activating receptor NKG2D, implicating this receptor in this function. NKG2D is ubiquitously expressed on NK cells and CD8+ T cells. Significantly, γ-irradiation of the vector eliminated the effect, suggesting that breakthrough expression from the vector induces at least some of the pro-inflammatory responses of unknown aetiology following the application of RDAd vectors during in vivo gene delivery.
Comparative analysis of the full genome sequence of European bat lyssavirus type 1 and type 2 with other lyssaviruses and evidence for a conserved transcription termination and polyadenylation motif in the G–L 3′ non-translated region
Authors: Marston D. A. , McElhinney L. M. , Johnson N. , Müller T. , Conzelmann K. K. , Tordo N. , Fooks A. R.
Published: March 2007

We report the first full-length genomic sequences for European bat lyssavirus type-1 (EBLV-1) and type-2 (EBLV-2). The EBLV-1 genomic sequence was derived from a virus isolated from a serotine bat in Hamburg, Germany, in 1968 and the EBLV-2 sequence was derived from a virus isolate from a human case of rabies that occurred in Scotland in 2002. A long-distance PCR strategy was used to amplify the open reading frames (ORFs), followed by standard and modified RACE (rapid amplification of cDNA ends) techniques to amplify the 3′ and 5′ ends. The lengths of each complete viral genome for EBLV-1 and EBLV-2 were 11 966 and 11 930 base pairs, respectively, and follow the standard rhabdovirus genome organization of five viral proteins. Comparison with other lyssavirus sequences demonstrates variation in degrees of homology, with the genomic termini showing a high degree of complementarity. The nucleoprotein was the most conserved, both intra- and intergenotypically, followed by the polymerase (L), matrix and glyco- proteins, with the phosphoprotein being the most variable. In addition, we have shown that the two EBLVs utilize a conserved transcription termination and polyadenylation (TTP) motif, approximately 50 nt upstream of the L gene start codon. All available lyssavirus sequences to date, with the exception of Pasteur virus (PV) and PV-derived isolates, use the second TTP site. This observation may explain differences in pathogenicity between lyssavirus strains, dependent on the length of the untranslated region, which might affect transcriptional activity and RNA stability.
Arabidopsis Nucleolin Affects Plant Development and Patterning
Authors: Petricka Jalean Joyanne , Nelson Timothy Mark
Published: March 2007

Nucleolin is a major nucleolar protein implicated in many aspects of ribosomal biogenesis, including early events such as processing of the large 35S preribosomal RNA. We found that the Arabidopsis (Arabidopsis thaliana) parallel1 (parl1) mutant, originally identified by its aberrant leaf venation, corresponds to the Arabidopsis nucleolin gene. parl1 mutants display parallel leaf venation, aberrant localization of the provascular marker Athb8:β-glucuronidase, the auxin-sensitive reporter DR5:β-glucuronidase, and auxin-dependent growth defects. PARL1 is highly similar to the yeast (Saccharomyces cerevisiae) nucleolin NUCLEAR SIGNAL RECOGNITION 1 (NSR1) multifunctional protein; the Arabidopsis PARL1 gene can rescue growth defects of yeast nsr1 null mutants. This suggests that PARL1 protein may have roles similar to those of the yeast nucleolin in nuclear signal recognition, ribosomal processing, and ribosomal subunit accumulation. Based on the range of auxin-related defects in parl1 mutants, we propose that auxin-dependent organ growth and patterning is highly sensitive to the efficiency of nucleolin-dependent ribosomal processing.
Comparative Genetic Mapping inBoechera stricta, a Close Relative of Arabidopsis
Authors: Schranz M. Eric , Windsor Aaron J. , Song Bao-hua , Lawton-Rauh Amy , Mitchell-Olds Thomas
Published: March 2007

The angiosperm family Brassicaceae contains both the research model Arabidopsis (Arabidopsis thaliana) and the agricultural genus Brassica. Comparative genomics in the Brassicaceae has largely focused on direct comparisons between Arabidopsis and the species of interest. However, the reduced genome size and chromosome number (n = 5) of Arabidopsis complicates comparisons. Arabidopsis shows extensive genome and chromosome reshuffling compared to its close relatives Arabidopsis lyrata and Capsella rubella, both with n = 8. To facilitate comparative genomics across the Brassicaceae we recently outlined a system of 24 conserved chromosomal blocks based on their positions in an ancestral karyotype of n = 8, rather than by their position in Arabidopsis. In this report we use this system as a tool to understand genome structure and evolution in Boechera stricta (n = 7). B. stricta is a diploid, sexual, and highly self-fertilizing species occurring in mostly montane regions of western North America. We have created an F2 genetic map of B. stricta based on 192 individuals scored at 196 microsatellite and candidate gene loci. Single-nucleotide polymorphism genotyping of 94 of the loci was done simultaneously using an Illumina bead array. The total map length is 725.8 cM, with an average marker spacing of 3.9 cM. There are no gaps greater than 19.3 cM. The chromosomal reduction from n = 8 to n = 7 and other genomic changes in B. stricta likely involved a pericentric inversion, a chromosomal fusion, and two reciprocal translocations that are easily visualized using the genomic blocks. Our genetic map will facilitate the analysis of ecologically relevant quantitative variation in Boechera.
The Mitogen-Activated Protein Kinase Cascade MKK3–MPK6 Is an Important Part of the Jasmonate Signal Transduction Pathway in Arabidopsis
Authors: Takahashi Fuminori , Yoshida Riichiro , Ichimura Kazuya , Mizoguchi Tsuyoshi , Seo Shigemi , Yonezawa Masahiro , Maruyama Kyonoshin , Yamaguchi-Shinozaki Kazuko , Shinozaki Kazuo
Published: March 2007

The plant hormone jasmonic acid (JA) plays a key role in the environmental stress responses and developmental processes of plants. Although ATMYC2/JASMONATE-INSENSITIVE1 (JIN1) is a major positive regulator of JA-inducible gene expression and essential for JA-dependent developmental processes in Arabidopsis thaliana, molecular mechanisms underlying the control of ATMYC2/JIN1 expression remain largely unknown. Here, we identify a mitogen-activated protein kinase (MAPK) cascade, MAPK KINASE 3 (MKK3)–MAPK 6 (MPK6), which is activated by JA in Arabidopsis. We also show that JA negatively controls ATMYC2/JIN1 expression, based on quantitative RT-PCR and genetic analyses using gain-of-function and loss-of-function mutants of the MKK3–MPK6 cascade. These results indicate that this kinase unit plays a key role in JA-dependent negative regulation of ATMYC2/JIN1 expression. Both positive and negative regulation by JA may be used to fine-tune ATMYC2/JIN1 expression to control JA signaling. Moreover, JA-regulated root growth inhibition is affected by mutations in the MKK3–MPK6 cascade, which indicates important roles in JA signaling. We provide a model explaining how MPK6 can convert three distinct signals—JA, pathogen, and cold/salt stress—into three different sets of responses in Arabidopsis.
TERMINAL FLOWER1 Is a Mobile Signal ControllingArabidopsisArchitecture
Authors: Conti Lucio , Bradley Desmond
Published: March 2007

Shoot meristems harbor stem cells that provide key growing points in plants, maintaining themselves and generating all above-ground tissues. Cell-to-cell signaling networks maintain this population, but how are meristem and organ identities controlled? TERMINAL FLOWER1 (TFL1) controls shoot meristem identity throughout the plant life cycle, affecting the number and identity of all above-ground organs generated; tfl1 mutant shoot meristems make fewer leaves, shoots, and flowers and change identity to flowers. We find that TFL1 mRNA is broadly distributed in young axillary shoot meristems but later becomes limited to central regions, yet affects cell fates at a distance. How is this achieved? We reveal that the TFL1 protein is a mobile signal that becomes evenly distributed across the meristem. TFL1 does not enter cells arising from the flanks of the meristem, thus allowing primordia to establish their identity. Surprisingly, TFL1 movement does not appear to occur in mature shoots of leafy (lfy) mutants, which eventually stop proliferating and convert to carpel/floral-like structures. We propose that signals from LFY in floral meristems may feed back to promote TFL1 protein movement in the shoot meristem. This novel feedback signaling mechanism would ensure that shoot meristem identity is maintained and the appropriate inflorescence architecture develops.
Accurate charge density of trialanine: a comparison of the multipole formalism and the maximum entropy method (MEM)
Authors: Hofmann Andreas , Netzel Jeanette , van Smaalen Sander
Published: March 2007

An accurate charge density study of trialanine is presented with the maximum entropy method (MEM), on the basis of the same reflection data as was used for a multipole refinement [Rödel et al. (2006). Org. Biomol. Chem.
4, 475–481]. With the MEM, the optimum fit to the data is found to correspond to a final value of χ2 which is less than its statistical expectation value N
Ref, where N
Ref is the number of reflections. A refinement strategy is presented that determines the optimal goal for χ2. It is shown that the MEM and the multipole method are on a par with regard to the reproduction of atomic charges and volumes, general topological features and trends in the charge density in the bond critical points (BCPs). Regarding the values of the charge densities in the BCPs, agreement between quantum chemical calculations, the multipole method and MEM is good, but not perfect. In the case of the Laplacians, the coincidence is not as good and especially the Laplacians of the C—O bonds differ strongly. One of the reasons for the observed differences in the topological parameters in the BCPs is the fact that MEM densities still include the effects of thermal motion, whereas multipole densities are free from the effects of thermal motion. Hydrogen bonds are more convincingly reproduced by the MEM than by multipole models.
Quantitative description of the tilt of distorted octahedra in ABX
3 structures
Authors: Tamazyan Rafael , van Smaalen Sander
Published: March 2007

A description of the tilt of octahedra in ABX
3 perovskite-related structures is proposed that can be used to extract the unique values for the tilt parameters φ, θ and δ of ABX
3 structures with regular and distorted octahedra up to the point symmetry \bar 1, from atomic coordinates and lattice parameters. The geometry of the BX
6 octahedron is described by three B—X bond lengths (r
1, r
2, r
3) and three X—B—X bond angles (ψ12, ψ13 and ψ23) or alternatively by a local strain tensor together with an average B—X bond length. Connections between the proposed method and Glazer's tilt system are discussed. The method is used to analyze structural transformations of I2/c, Pbnm and Immm structures. The proposed description allows the analysis of group–subgroup relations for the ABX
3 structures with distorted octahedra, in terms of octahedral deformations and tilting. The method might also be of interest in the study of the phase transitions in the family of ABX
3 structures.
Optimal partitioning of molecular properties into additive contributions: the case of crystal volumes
Authors: Beaucamp Sylvain , Mathieu Didier , Agafonov Viatcheslav
Published: March 2007

A systematic scheme to split the volume of molecular crystals into additive increments is discussed. In contrast to earlier procedures, it relies on the definition of atom types on the basis of their geometrical rather than chemical environment. In addition, the role of the relevant structural features of the compounds is explicitly taken into account. This approach provides insight into the relative influence of chemical bonds, hydrogen bonds and rings on the volume of organic crystals. Compared with group-contribution techniques, it yields very similar results with many fewer empirical parameters. Applied to estimate the densities of 42 880 crystals containing elements up to chlorine and measured at different temperatures, an average absolute deviation from experiment close to 2% is obtained.
Triclinic apatites
Authors: Baikie Tom , Mercier Patrick H. J. , Elcombe Margaret M. , Kim Jean Y. , Le Page Yvon , Mitchell Lyndon D. , White T. J. , Whitfield Pamela S.
Published: March 2007

Apatites commonly adopt P63/m hexagonal symmetry. More rarely, monoclinic chemical analogues have been recognized, including the biologically significant hydroxyapatite, Ca10(PO4)6(OH)2, but the driving force towards lower symmetry has not been systematically examined. A combination of diffraction observations and ab initio calculations for Ca10(AsO4)6F2 and Ca10(VO4)6F2 show these materials are triclinic P\bar 1 apatites in which the AsO4 and VO4 tetrahedra tilt to relieve stress at the metal and metalloid sites to yield reasonable bond-valence sums. An analysis of the triclinic non-stoichiometric apatites La10 − x
(GeO4)6O3 − 1.5x
and Ca10(PO4)6(OH)2 − x
O
x/2 confirms this scheme of tetrahedral rotations, while Cd10(PO4)6F2 and Ca10(CrO4)6F2 are predicted to be isostructural. These distortions are in contrast to the better known P1121/b monoclinic dimorphs of chloroapatite and hydroxyapatite, where the impetus for symmetry reduction is ordered anion (OH− and Cl−) displacements which are necessary to obtain acceptable bond lengths. These results are important for designing apatites with specific structural and crystal-chemical characteristics.
Influence of fluoro-substitution on the planarity of 4-chlorobiphenyl (PCB 3)
Authors: Luthe G. , Swenson D. C. , Robertson L. W.
Published: March 2007

Accurate structure determinations by X-ray crystal analysis and computation using semi-empirical self-consistent field molecular orbital calculations are described and compared for five monofluorinated analogues of 4-chlorobiphenyl, i.e. 2-fluoro-4-chlorobiphenyl, 2′-fluoro-4-chlorobiphenyl, 3-fluoro-4-chlorobiphenyl, 3′-fluoro-4-chlorobiphenyl and 4′-fluoro-4-chlorobiphenyl. Intermolecular interactions for all monofluorinated isomers are dominated by phenyl–phenyl stacking and C—H–phenyl interactions. C—F bond lengths varied between 1.341 and 1.374 Å, C—Cl between 1.733 and 1.765 Å, and both correlate with electron-density differences as determined by 13C NMR shifts. The interior ring angles at ipso-fluoro substitution increase up to 122.2–124.2° due to hyperconjugation by 2p-π-orbital overlapping, a phenomenon that was also reflected in the computer calculation. The angles of C—F and C—Cl relative to the aromatic ring for vicinal fluoro- and chloro substituents show an attraction, not a repulsion, between the adjacent F and Cl substituents. This finding is explained on the basis of electron donor and acceptor properties. The dihedral angles of ortho-substituted biphenyls show that monofluoro substitution results in slightly smaller increases compared with chlorine, while additional ortho-fluorination results in little further change in the dihedral angle. In contrast, ortho-chlorination strongly decreases the co-planarity. This is likely to be due to interior ring-angle distortion and the size of the halogen substituent. Fluoro substitution does indeed affect the planarity of the PCB3 analogues, but these effects are minor compared with chloro substitution. Fluorine tagging offers promise for use in in vitro and in vivo studies. Differences in computational versus measured data emphasize the need to use a variety of methods to ascertain the true nature of the physical properties of a compound.
Polymorphism of 4-bromobenzophenone
Authors: Strzhemechny Mikhail A. , Baumer Vyacheslav N. , Avdeenko Anatoli A. , Pyshkin Oleg S. , Romashkin Roman V. , Buravtseva Lyubov M.
Published: March 2007

A combination of single-crystal and powder X-ray diffractometry was used to study the structure of two polymorphs of 4-bromobenzophenone over the temperature range from 100 to 300 K. One of the polymorphs of the title compound was known previously and its structure has been determined at room temperature [Ebbinghaus et al. (1997). Z. Kristallogr.
212, 339–340]. Two crystal growth methods were employed, one of which (a modification of the Bridgman–Stockbarger technique) resulted in single crystals of a previously unknown structure. The basic physical properties of the stable polymorph are: growth method, from 2-propanol solutions or gradient sublimation; space group, monoclinic P21/c; melting point, T
m = 355.2 K; X-ray density (at 100 K), Dx
= 1.646 g cm−3. The same properties of the metastable polymorph (triclinic P\overline 1 ) are: growth method, modified Bridgman–Stockbarger method; X-ray density (at 100 K), Dx
= 1.645 g cm−3; T
m = 354 K. Thermograms suggest that the melting of the metastable form is accompanied by at least a partial crystallization presumably into the monoclinic form; the transformation is therefore monotropic. Analysis of short distances in both polymorphs shows that numerous weak hydrogen bonds of the C—H...π type ensure additional stabilization within the respective planes normal to the longest dimension of the molecules. The strong temperature dependence of the lattice constants and of the weak bond distances in the monoclinic form suggest that the weak bond interactions might be responsible for both the large thermal expansion within plane bc and the considerable thermal expansion anisotropy.
LTN-type zeolite framework as an interpenetrating net of KFI- and SOD-type parts homeomorphic to cuprite, Cu2O
Authors: Baur Werner H. , Fischer Reinhard X.
Published: March 2007

The complex LTN-type zeolite framework is described as consisting of two interpenetrating parts in order to understand the connectivities of their underlying nets. Both parts are homeomorphic to diamond-type tetrahedral frameworks, arranged in principle in the same manner as the two interpenetrating frameworks in cuprite, Cu2O. However, in cuprite the two frameworks are identical, while in the LTN-type framework one is made up of two kinds of truncated octahedra (toc units) and can be described as one half of the sodalite-type framework (SOD). The other consists of large cages, so-called truncated cubo-octahedra (grc units) connected by hexagonal prisms (double six-rings) and corresponds to one half of the KFI-type framework. Neither of the sub-frameworks has so far been observed in any other zeolite topology. The two sub-frameworks of SOD and KFI types in the interpenetrating LTN-type framework are models for very open interrupted frameworks, which possibly could be synthesized separately in a pure form. Their framework density would be 7.6 T atoms per 1000 Å3 if they could be prepared as aluminosilicates.
Influence of polyhedron distortions on calculated bond-valence sums for cations with one lone electron pair
Authors: Wang X. , Liebau F.
Published: March 2007

In the present bond-valence model (BVM), the bond-valence parameters r
0 and b are, in general, supposed to be constant for each A–X pair and equal to 0.37 Å for all A–X pairs, respectively. For [A

i
(X

j
)
n
] coordination polyhedra that do not deviate strongly from regularity, these suppositions are well fulfilled and calculated values for the bond-valence sums (BVS)
i
are nearly equal to the whole-number values of the stoichiometric valence. However, application of the BVM to 2591 [L

i
(X

j
)
n
] polyhedra, where L are p-block cations, i.e. cations of the 13th to 17th group of the periodic system of elements, with one lone electron pair and X = O−II, S−II and Se−II, shows that r
0i
values of individual [LX

n
] polyhedra are correlated with the absolute value |Φ

i
| of an eccentricity parameter, Φ

i
, which is higher for more distorted [LX

n
] polyhedra. As a consequence, calculated (BVS)
i
values for these polyhedra are also correlated with |Φ

i
|, rather than being numerically equal to the stoichiometric valence of L. This is interpreted as the stereochemical influence of the lone electron pair of L. It is shown that the values of the correlation parameters and the R
2 values of the correlation equations depend on the position of the L cation in the periodic system of elements, if the correlations are assumed to be linear. This observation suggests that (BVS)
L
describes a chemical quantity that is different from the stoichiometric valence of L.
Superspace description of the crystal structures of Ca
n
(Nb,Ti)
n
O3n + 2 (n = 5 and 6)
Authors: Guevarra Jonathan , Schönleber Andreas , van Smaalen Sander , Lichtenberg Frank
Published: March 2007

The crystal structures of two members of the homologous series Ca
n
(Nb,Ti)
n
O3n + 2, with n = 5 and 6, are presented within the superspace formalism. A common (3 + 1)-dimensional superspace model is used to describe the crystal structures of both compositions within a particular homologous series, where the primary modulation wavevector and the width of the atomic domains vary systematically with composition. The two crystal structures are characterized as commensurately modulated structures consisting of discontinuous atomic domains described by occupational crenel functions. The displacive modulation functions for the two compounds exhibit similarities, but they also show that the idea of a unified superspace model does not extend toward the precise atomic positions. For n = 6, the centrosymmetric (3 + 1)-dimensional superspace symmetry provides a natural explanation for the pseudo-symmetries that are present in the non-centrosymmetric (three-dimensional) superstructure of this compound. The efficiency of the superspace approach is demonstrated by structure refinements in (3 + 1)-dimensional superspace and by comparing these results with the refinements in their three-dimensional superstructures.
Chemical bonding and intermolecular interactions in energetic materials: 1,3,4-trinitro-7,8-diazapentalene
Authors: Chen Yu-Sheng , Stash Adam I. , Pinkerton A. Alan
Published: March 2007

The electron density and related properties of the red-colored energetic material 1,3,4-trinitro-7,8-diazapentalene (space group Pca21) have been determined from a low-temperature [90.0 (1) K] X-ray diffraction experiment. Intensity data were measured with a 2 K CCD Bruker diffractometer using Ag Kα radiation. One detector setting, several φ settings, 0.15° ω scans and 96 s exposure time per frame gave R
int = 0.0188 for 31 952 (10 283 unique) reflections and (sin θ/λ)max = 1.15 Å−1. The electron density was modeled using the Hansen–Coppens [(1978), Acta Cryst. A34, 909–921] multipole model and refined to R = 0.026 for 9455 unique observed reflections. The electron density, Laplacian and electrostatic potential distributions are reported and discussed. The properties of the bond (3,−1) critical points are analyzed. All results are indicative of multiple bonds in the five-membered rings. In addition, a significant number of weak intermolecular interactions (O...H, O...O, O...N, O...C) have also been characterized by the properties of their critical points. A comparison of experimental results with those obtained from theoretical calculations (periodic, CRYSTAL98; single molecule, GAUSSIAN98) is also reported.
Structures of three dehydration products of bischofite from in situ synchrotron powder diffraction data (MgCl2·nH2O; n = 1, 2, 4)
Authors: Sugimoto Kunihisa , Dinnebier Robert E. , Hanson Jonathan C.
Published: March 2007

High-quality in situ synchrotron powder diffraction data have been used to investigate the decomposition products of bischofite in the temperature range 298 ≤ T ≤ 873 K. At least eight phases could be identified: MgCl2·nH2O (n = 1, 2, 4 and 6), MgOHCl·nH2O (0 ≤ n ≤ 1.0), MgCl2 and MgO. The crystal structures of three magnesium chloride hydrates MgCl2·nH2O (n = 1, 2, 4) were determined ab initio, replacing published Rietveld refinements from low-quality powder diffraction data based on similarity criteria. MgCl2·4H2O was found to be disordered and has been correctly determined for the first time. The crystal structures of bischofite and MgCl2·4H2O consist of discrete Mg(H2O)6 and MgCl2(H2O)4 octahedra, respectively. The crystal structure of MgCl2·2H2O is formed by single chains of edge-sharing MgCl2(H2O)4 octahedra, while in the case of MgCl2·H2O double chains of edge-sharing MgCl(H2O)5 octahedra are found. The phases in the system MgCl2–H2O are intermediates in the technologically important process of MgO and subsequently Mg production. The same phases were recently found to be of key importance in the understanding of cracks in certain magnesia concrete floors.
Systematic prediction of new ferroelectrics in space group R3. II
Authors: Abrahams S. C.
Published: March 2007

Release 2006/1 of the Inorganic Crystal Structure Database contains 155 entries under space group R3. Atomic coordinate analysis of the first 81 structures, with 52 different structure types, in Part I [Abrahams (2006). Acta Cryst. B62, 26–41] identified a total of 18 new types that satisfy the structural criteria for ferroelectricity, five that are more likely to have or undergo a transition to 3m symmetry, 19 more likely to be or undergo a transition to nonpolar symmetry and ten with a lower property predictability. Coordinate analysis of the remaining 71 entries with 54 different structure types in Part II leads to 11 materials including Al4B6O15, PbTa3(PO4)(P2O7)3.5, the KCd4Ga5S12 family, the LiZnPO4 family, Ca3Nb1.95O8V0.05 and Mn4Ta2O9 as new candidates which satisfy the structural criteria, together with the three known ferroelectrics Na3MoO3F3, Pb2ScTaO6, and RbTi2(PO4)3 at 6.2 GPa. Two additional ferroelectric predictions are at a lower level of confidence. The analysis also reveals nine materials, two of which are isostructural, that more likely belong or are capable of undergoing a transition to crystal class 3m. There are 14 additional structure types which are more likely to be nonpolar or undergo a transition to nonpolarity, ten have reduced predictive properties, with a further nine for which the space group is expected to remain R3 over the full thermal stability range. The increasing use of methods for identifying overlooked inversion centers in structural determinations may be extended by using coordinate analysis for detecting additional commonly overlooked symmetry elements.
Frequency and Predictors of Return to Incentive Spirometry Volume Baseline After Cardiac Surgery
Authors: Harton Suzanne C. , Grap Mary Jo , Savage Laura , Elswick R.K.
Published: March 2007

Incentive spirometry (IS) is routinely used in most clinical settings, but evaluation of patient efficacy of IS is not standardized. The purpose of this study was to describe the degree and predictors of return to preoperative IS volume after cardiac surgery. IS volumes were documented in 69 subjects (71% men; mean age, 59 years) undergoing cardiac surgery during the preoperative evaluation and twice daily postoperatively. Nineteen percent of subjects achieved their IS preoperative volume by hospital discharge. Based on highest volume achieved, subjects achieved an average of 75% of their preoperative volume by discharge, and only age and number of bypass grafts predicted return to preoperative IS volume. These data may assist nurses and patients to set realistic goals for postoperative IS volume achievement.
Current Endovascular Treatment of Peripheral Arterial Disease
Authors: Mardikar H.M. , Mukherjee Debabrata
Published: March 2007

Atherosclerotic peripheral arterial disease is a common medical problem worldwide and portends a poor prognosis because of increased cardiovascular morbidity and mortality. Regular exercise, weight loss, and aggressive risk factor modification, including treatment of dyslipidemia and complete cessation of smoking, is extremely important in this high‐risk cohort. Vascular surgery in these patients, who often have concomitant coronary or cerebrovascular atherosclerosis, is associated with significant risk. Steady improvements in endovascular revascularization techniques have made this a safe and effective alternate revascularization modality. Percutaneous peripheral vascular interventions have increased dramatically in recent years, from 90,000 in 1994 to more than 200,000 in 1997, and endovascular techniques may soon replace up to 50% of traditional vascular operations. In this article, the authors review the current state of interventional treatment for peripheral arterial disease.
Black, Hispanic, and White Women's Perception of Heart Disease
Authors: Arslanian‐Engoren Cynthia
Published: March 2007

Understanding why women delay seeking treatment for symptoms suggestive of an acute myocardial infarction remains elusive. Thirty individual semistructured interviews were conducted to determine black (n=10), Hispanic (n=10), and white (n=10) women's perception of heart disease risk and whether differences existed based on participant's race or ethnicity. Narrative descriptions analyzed using the Morse and Field method revealed that women, regardless of race or ethnicity, associated heart disease and heart attacks with men who were obese, stressed, and smokers. Perceptions of heart disease risk were similar between groups, with women generally believing they were at risk for heart disease because of family history, diet, and obesity. Racial and ethnic differences were noted, however, in risk reduction and anticipated treatment‐seeking behaviors. Continued efforts are needed to raise women's perception of their cardiac risks and the need for the engagement in health‐promoting behaviors.
Evaluation of a Web‐Based Education and Counseling Pilot Program for Older Heart Failure Patients
Authors: Westlake Cheryl , Evangelista Lorraine S. , Strömberg Anna , Ter‐Galstanyan Alvina , Vazirani Sondra , Dracup Kathleen
Published: March 2007

Web‐based communication has been reported as a feasible management tool for heart failure (HF) patients and has also been documented to positively impact quality of life (QOL). The feasibility and effectiveness of a Web‐based educational and HF management program among older HF patients (60 years and older), however, have not been previously explored. Therefore, a prospective study was conducted. QOL (physical and mental health) and perceived control (PC) scores of 40 participants were measured (baseline and 3 months) and retrospectively compared with an age‐ and sex‐matched control group of 40 patients receiving HF care as usual. Between‐group differences over time were statistically significant in the QOL mental health component and PC scores. The authors' findings demonstrate the beneficial effects of a Web‐based program on QOL and PC in older patients with HF. This approach may be potentially beneficial in delivering educational and behavioral support to this high‐risk group in ways that are affordable and accessible.
Sleep Disturbances in Caregivers of Patients With End‐Stage Congestive Heart Failure: Part I—The Problem
Authors: Rausch Sarah M , Baker Kathy , Boonmee Junyanee
Published: March 2007

Up to 90% of caregivers report sleep disturbances, particularly congestive heart failure (CHF) caregivers. Sleep disturbances have numerous consequences that can negatively impact a wide domain of outcomes in both the caregiver and the patient for whom they care. Ultimately, these disturbances can lead to caregiver morbidity and CHF patient morbidity, readmission, and mortality. Nurses play a central role in patient education, especially with caregivers. Therefore, nurses can help to educate caregivers on the consequences of stress‐related sleep disturbances, which are very prevalent in CHF caregivers.
The Dangers of Cardiac Myxomas
Authors: Roschkov Sylvia , Rebeyka Darlene , Mah Jean , Urquhart Gayle
Published: March 2007

A variety of cardiac tumors have been acknowledged in the literature since the 16th century as rare forms of cardiac disease. Of the primary tumors, myxomas account for at least 30% to 50% of benign tumors. Despite significant advances in cardiac diagnostics leading to early recognition of myxomas, the potential for deleterious effects secondary to embolic complications remains high. The purpose of this paper is to provide nurses with an understanding of the epidemiology, pathology, clinical presentation, and assessment of individuals with cardiac myxomas. A case presentation is used to illustrate how the misdiagnosis of cardiac myxoma led to a delay in patient treatment. Prompt recognition, diagnosis, and treatment are important in improving patient outcomes and quality of life. Due to the infrequency of cardiac myxomas, ensuring appropriate preoperative and postoperative nursing care to the patient with a cardiac myxoma is essential.
Outcomes Following Surgical Ventricular Restoration in Elderly Patients With Congestive Heart Failure
Authors: Williams Jason A. , Patel Nishant D. , Nwakanma Lois U. , Conte John V.
Published: March 2007

Despite the well described benefits of surgical ventricular restoration (SVR) for patients with ischemic cardiomyopathy, the effects of advanced age on outcomes following this procedure have not been well documented. The authors compared outcomes in 69 consecutive patients 65 years and older (n=27) and younger than 65 years (n=42) to determine the utility of SVR in an elderly population with end‐stage heart failure. Patients 65 years and older demonstrated significant improvements in ejection fraction (P=.01) and left ventricular end‐systolic volume index (P=.07) following SVR, which were similar to the improvements seen in patients younger than 65 years. Sixty percent (15 of 25) of patients 65 years and older in preoperative New York Heart Association class III/IV improved to class I/II at follow‐up (P<.0001). Actuarial survival was 68.8% at 2.5 years. Like their younger counterparts, elderly patients demonstrate significant improvements in ventricular function and NYHA class with acceptable survival following SVR.
Anemia Does Not Predict Mortality in Elderly Patients With Heart Failure
Authors: Kerzner Roger , Gage Brian F. , Rich Michael W.
Published: March 2007

Recent studies suggest that anemia is an independent predictor of adverse outcomes in patients with heart failure (HF), but the importance of anemia in elderly HF patients is unclear. To investigate this relationship, the authors quantified the prognostic importance of anemia in elderly vs younger patients with HF was performed. A chart review of 359 patients hospitalized in 1999 with HF was performed. Patients were categorized based on their hemoglobin (Hgb) level (<11.5, 11.5–13.4, >13.4 g/dL), and the authors used time‐to‐event analyses to test the hypothesis that Hgb predicted mortality over a mean follow‐up of 25 months. Lower Hgb predicted worse survival in patients younger than 75 years (n=204; P=.03), but there was no correlation between Hgb level and mortality in patients 75 or older (n=155; Pnot significant). The authors conclude that anemia is not an important predictor of long‐term survival in very elderly patients hospitalized with HF.
Depression and Nursing Home Admission Among Hospitalized Older Adults With Coronary Artery Disease: A Propensity Score Analysis
Authors: Ahmed Ali , Lefante Christina M. , Alam Nazmul
Published: March 2007

Admission to a nursing home is considered a poor outcome for community‐dwelling older adults. The objective of this study was to determine whether depression increased the risk of nursing home admission. Using the National Hospital Discharge Survey 2001–2003 datasets, the authors identified 28,172 community‐dwelling older adults, 65 years and older, discharged alive with a primary discharge diagnosis of coronary artery disease. The objective of this study was to determine the association between depression and subsequent nursing home admissions in these patients. Propensity scores for depression, calculated for each patient using a multivariable logistic regression model, were used to match 686 depressed patients with 2058 nondepressed patients who had similar propensity scores. Logistic regression analyses were used to determine the association between depression and nursing home admission. Patients had a mean age ± SD of 77±8 years, and 61% were women. Compared with 9% of nondepressed patients, 13% of depressed patients were admitted to nursing homes (relative risk, 1.42; 95% confidence interval, 1.12–1.78). When adjusted for various demographic, clinical, and care‐related covariates, the association became somewhat stronger (adjusted relative risk, 1.55; 95% confidence interval, 1.21–1.99). In ambulatory older adults hospitalized with coronary artery disease, a secondary diagnosis of depression was associated with a significantly increased risk of nursing home admission.
Sex and Racial Differences in Outcomes and Guideline‐Based Management of Troponin‐Only‐Positive Acute Myocardial Infarction in Older Persons
Authors: Shah Rahman , Wang Yun , Masoudi Frederick A. , Foody JoAnne M.
Published: March 2007

Multiple studies have shown sex and racial differences in the management and outcomes of ischemic heart disease, but whether these sex and racial disparities persist in patients with troponin‐only‐positive acute myocardial infarction (AMI) is unknown. The authors evaluated a nationwide sample of eligible Medicare beneficiaries, 65 years or older, who were hospitalized (N=71,120) with a primary discharge diagnosis of AMI. Analysis was restricted to patients with troponin‐only‐positive AMI (n=5897) and was substratified into 4 groups: white men, white women, nonwhite men, and nonwhite women. The authors found that the traditional sex and racial disparities in the evidence‐based medication prescriptions for ischemic heart diseases resolved in this cohort of older patients. Similarly, in settings of equal care, sex and race seem to have no impact on the outcomes for older patients with troponin‐only‐positive AMI.
An Invasive Strategy Is Associated With Decreased Mortality in Patients 80 Years and Older With Acute Myocardial Infarction
Authors: Schloss Timothy W. , Gage Brian F. , Rich Michael W.
Published: March 2007

The value of invasive therapy in elderly patients with acute myocardial infarction is controversial. The authors performed a retrospective chart review of 140 consecutive patients 80 years and older who were hospitalized with acute myocardial infarction. Hospital outcomes and long‐term survival were compared in 79 patients referred for cardiac catheterization during hospitalization with outcomes in 61 patients managed conservatively. Vital status as of December 2003 was determined from the Social Security Death Index. Propensity analysis was used to limit confounding from 13 variables. After a mean follow‐up of 333 days, unadjusted mortality was lower in the invasive group (16.5% vs 50.8%;P<.001). The multivariable propensity‐adjusted hazard ratio for death was 0.30 (95% confidence interval, 0.11–0.76;P=.01), favoring the invasive group. These data suggest that in patients 80 years and older who are hospitalized with acute myocardial infarction, an invasive strategy confers a significant survival advantage during the first year after hospital discharge.
Micromorphology of soils derived from volcanic ash in Europe: a review and synthesis
Authors: Stoops G.
Published: March 2007

An analysis of the available literature on European volcanic ash soils has been made. Most has been published in Congress proceedings and Journals of national societies, less than half in English. More than half of the papers deal with soils on the Canary Islands. Many papers focus only on one aspect, and complete descriptions are found only in recent publications. Often the use of vague micromorphological terminology and the absence of analytical data make interpretation and comparisons difficult or impossible. Nonetheless, some general features do emerge. In the least‐weathered soils, the micromass forms first coatings around the coarse constituents, later granules, finally giving rise to a loose granular microstructure in the topsoil, and a compacted granular one in the Bw horizons of typic andic materials. The b‐fabric of the micromass is undifferentiated. With increasing weathering, clay coatings appear, the microstructure becomes more blocky and the b‐fabric becomes speckled or even striated. In Vertisols and Aridisols, micromorphological characteristics are not much different from those in the comparable non‐volcanic soils, except generally for the tendency to granular (intrapedal) microstructures. In Icelandic soils, microstratification, lenticular microstructure and preservation of plant residues as a result of cryic conditions and permanent volcanic and aeolian activity are observed. Weathering of volcanic glass in well‐drained conditions yields allophane alteromorphs similar to palagonite, which are easily subject to fragmentation by pedoturbation. The possible influence of surface transport and burial on the formation of Bw‐horizons in andic materials is discussed.