Related Articles

Corrigenda for five articles.

The affiliation of one of the authors and a source of funding are both added in the following papers: Chiririwa & Meijboom [Acta Cryst. (2011a), E67, m1496; Acta Cryst. (2011b), E67, m1497; Acta Cryst. (2011c), E67, m1498] and Chiririwa & Muller [Acta Cryst. (2012a), E68, m49; Acta Cryst. (2012b), E68, m116–m117].

The article by Natarajan & Mathews [(2012) (2012) Acta Cryst. F68, 207–210] is retracted.

The article by Natarajan & Mathews [(2012) Acta Cryst. F68, 207–210] is retracted.

A corrigendum to the article by Dutta et al. [(2012) Acta Cryst. F68, 786–789].

In the article by Dutta et al. [(2012) Acta Cryst. F68, 786–789] two citations were given erroneously. These are now corrected.

An addendum to the article by Do et al. [(2012) Acta Cryst. F68, 806–809].

An additional acknowledgement is published for the article by Do et al. [(2012) Acta Cryst. F68, 806–809].

Objective

To determine the effect of an endothelin type A receptor antagonist (ETA) on uterine artery resistive index (UARI) and mean arterial pressure (MAP) in a placental ischemia rat model of pre-eclampsia produced by Reductions in Uterine Perfusion Pressure (RUPP).

Study Design

UARI was assessed by Doppler velocimetry in the RUPP and normal pregnant controls (NP) on gestation days (GD) 12, 15 and 18. UARI was also determined on GD 18 in NP and RUPP pregnant dams after pretreatment with ETA. MAP was recorded on GD 19.

Results

The RUPP group had a higher MAP and UARI on GD 15 and 18 than the NP group. Pretreatment with ETA attenuated both the MAP and GD 18 UARI in the RUPP group without affecting these parameters in the NP group.

Conclusion

The improvement in UARI could be one potential mechanism for the reduction in MAP in response to ETA in pregnant dams with ischemic placentas.

The accuracy of a dispersion-corrected density functional theory method is validated against 241 experimental organic crystal structures from Acta Cryst. Section E.

This paper describes the validation of a dispersion-corrected density functional theory (d-DFT) method for the purpose of assessing the correctness of experimental organic crystal structures and enhancing the information content of purely experimental data. 241 experimental organic crystal structures from the August 2008 issue of Acta Cryst. Section E were energy-minimized in full, including unit-cell parameters. The differences between the experimental and the minimized crystal structures were subjected to statistical analysis. The r.m.s. Cartesian displacement excluding H atoms upon energy minimization with flexible unit-cell parameters is selected as a pertinent indicator of the correctness of a crystal structure. All 241 experimental crystal structures are reproduced very well: the average r.m.s. Cartesian displacement for the 241 crystal structures, including 16 disordered structures, is only 0.095 Å (0.084 Å for the 225 ordered structures). R.m.s. Cartesian displacements above 0.25 Å either indicate incorrect experimental crystal structures or reveal interesting structural features such as exceptionally large temperature effects, incorrectly modelled disorder or symmetry breaking H atoms. After validation, the method is applied to nine examples that are known to be ambiguous or subtly incorrect.

In the crystal structure of the title compound, C16H14F3N3OS·C3H8O, the mol­ecules are linked into chains along [010] via N—H⋯O and O—H⋯N hydrogen bonds. The triclinic form was reported by Ren et al. [(2011). Acta Cryst. E67, o270] and the first monoclinic form by Chen et al. [(2012). Acta Cryst. E68, o2015–o2016]. The fused five-and six-membered rings make a dihedral angle of 1.22 (2)°, while the benzene and pyridine rings make a dihedral angle of 10.15 (2)°.

Birch pollen is one of the main causes of allergy during spring and early summer in northern and central Europe. The aim of this study was to create a forecast model that can accurately predict daily average concentrations of Betula sp. pollen grains in the atmosphere of Szczecin, Poland. In order to achieve this, a novel data analysis technique—artificial neural networks (ANN)—was used. Sampling was carried out using a volumetric spore trap of the Hirst design in Szczecin during 2003–2009. Spearman’s rank correlation analysis revealed that humidity had a strong negative correlation with Betula pollen concentrations. Significant positive correlations were observed for maximum temperature, average temperature, minimum temperature and precipitation. The ANN resulted in multilayer perceptrons 366 8: 2928-7-1:1, time series prediction was of quite high accuracy (SD Ratio between 0.3 and 0.5, R > 0.85). Direct comparison of the observed and calculated values confirmed good performance of the model and its ability to recreate most of the variation.

A corrigendum to the article by Najmudin et al. [Acta Cryst. (2009). F65, 730–732].

A correction is made to the name of one of the authors in the article by Najmudin et al. [Acta Cryst. (2009). F65, 730–732].

Preeclampsia is associated with innate inflammatory response resulting in elevated TNF alpha, agonistic autoantibodies to the angiotensin II type I receptor (AT1-AA) and activation of endothelin-1 (ET-1). This study was designed to determine the role of B cell depletion, resulting AT1-AA suppression to mediate hypertension via activation of ET-1 in placental ischemic RUPP rat model of preeclampsia. To achieve this goal we examined the effect of RUPP on MAP and ET-1 in the presence and absence of chronically infused Rutiximab (R) (250mg/kg), a B lymphocyte suppressive agent used clinically to treat autoimmune diseases. Blood pressure (MAP) was 103 +/− 1 mmHg in NP;103 +/− 3 mmHg in NP+R vs 133 +/−2 mmHg in RUPP rats and 118 +/−2 mmHg in RUPP+R (p<0.001vs RUPP controls). B lymphocytes decreased from 6.0 +/−0.5% in RUPP to 3.7 +/−0.8 % gated cells in RUPP+R. Importantly, AT1-AA decreased from 18+/−1 in RUPP to 10+/−1bpm in RUPP+R. ET-1 decreased 1.5 fold in kidneys and 4 fold in placenta (P<0.01) of RUPP+R vs RUPP. Media ET-1 excretion from endothelial cells exposed to serum from NP, RUPP, NP+R or RUPP+R rats was determined. ET-1 from endothelial cells treated with NP serum was 53+13pg/mg and increased to 75+10pg/mg with RUPP serum. In contrast ET-1 secretion decreased in response to B cell depleted RUPP serum to 50+/−8pg/mg, and was unchanged in response to NP+R sera (46+/−12 pg/mg). These data demonstrate the important role that B lymphocyte activation and AT1-AAs play in the pathophysiology of hypertension in response to placental ischemia.

A corrigendum to the article by Ito et al. [Acta Cryst. (2008). F64, 531–532].

A correction is made to the list of authors for Ito et al. [Acta Cryst. (2008). F64, 531–532].

An addition to the paper by Cheng et al. [(2010), Acta Cryst. F66, 546–548].

An author is added to the article by Cheng et al. [(2010), Acta Cryst. F66, 546–548].

A correction to the paper by Asojo et al. [(2005), Acta Cryst. F61, 391–394].

Data collection and instrument information reported in the article by Asojo et al. [(2005), Acta Cryst. F61, 391–394] are corrected.

The crystal structure of dizinc trimolybdenum(IV) octa­oxide, Zn2Mo3O8, has been redetermined from single-crystal X-ray data. The structure has been reported previously based on neutron powder diffraction data [Hibble et al. (1999 ▶). Acta Cryst. B55, 683-697] and single-crystal data [McCarroll et al. (1957 ▶). J. Am. Chem. Soc. 79, 5410–5414; Ansell & Katz (1966 ▶) Acta Cryst. 21, 482–485]. The results of the current redetermination show an improvement in the precision of the structural and geometric parameters with all atoms refined with anisotropic displacement parameters. The crystal structure consists of distorted hexa­gonal-close-packed oxygen layers with stacking sequence abac along [001] and is held together by alternating zinc and molybdenum layers. The Zn atoms occupy both tetra­hedral and octa­hedral inter­stices with a ratio of 1:1. The Mo atoms occupy octa­hedral sites and form strongly bonded triangular clusters involving three MoO6 octa­hedra that are each shared along two edges, forming a Mo3O13 unit. All atoms lie on special positions. The Zn atoms are in 2b Wyckoff positions with 3m. site symmetry, the Mo atoms are in 6c Wyckoff positions with . m. site symmetry and the O atoms are in 2a, 2b and 6c Wyckoff positions with 3m. and . m. site symmetries, respectively.

In the six-membered ring of the low-temperature crystal structure of benzofurazan 1-oxide, C6H4N2O2, the two C atoms adjacent to the N atoms are linked by a delocalized aromatic bond [1.402 (2) Å]; each is connected to its neighbour by a longer, more localized, bond [1.420 (2), 1.430 (2) Å]. However, the next two bonds in the ring approximate double bonds [1.357 (2), 1.366 (2) Å]. As such, the six-membered ring is better described as a cyclo­hexa­diene system, in contrast to the description in the room-temperature structure reported by Britton & Olson (1979 ▶) [Acta Cryst. B35, 3076–3078].

The title salt, C12H24N+·NCS−, represents a monoclinic polymorph of the previously reported ortho­rhom­bic form [Khawar Rauf et al. (2008 ▶). Acta Cryst. E64, o366]. Two independent formula units comprise the asymmetric unit with the major difference in their mol­ecular structures relating to the relative dispositions of the cyclo­hexyl rings [dihedral angles = 79.88 (6) and 67.72 (5)°]. Further, the independent anions form distinctive patterns of hydrogen-bonding inter­actions, i.e. 2 × N—H⋯N versus N—H⋯N and N—H⋯S. The resulting supra­molecular architecture is a supra­molecular chain along the c axis based on a square-wave topology.

Corrigendum to Acta Cryst. (2009), E65, o301.

Consideration of a previous unrecognized twinning of the original investigated crystal of the title compound [Kia et al. (2009 ▶). Acta Cryst. E65, o301] led to improved reliability factors and to a slightly higher precision for all geometric parameters. The crystal under investigation was twinned by pseudo-merohedry with [100, 00, 00] as the twin matrix and a refined twin domain fraction of 0.9610 (5):0.0390 (5). The results of the new crystal structure refinement are given here.

The title ferrocene derivative, [Fe(C5H5)(C14H13FNO)], crystallizes in the same space group with similar unit-cell parameters as the derivatives 3-anilino-1-ferrocenylpropan-1-one [Leka et al. (2012 ▶). Acta Cryst. E68, m229] and 1-ferrocenyl-3-(4-methyl­anilino)propan-1-one [Leka et al. (2012 ▶). Acta Cryst. E68, m230]. The dihedral angle between the best planes of the benzene ring and the substituted cyclo­penta­dienyl ring is 83.4 (1)°. The presence of the electronegative fluoro substituent in the meta position of the aniline group does not alter the crystal packing compared to the other two derivatives. The molecules are connected into centrosymmetric dimers via N—H⋯O hydrogen bonds. In addition, C—H⋯O and C—H⋯N contacts stabilize the crystal packing.

Corrigendum to Acta Cryst. (2012), E68, o1366.

The title and Scheme in the paper by Wang et al. [Acta Cryst. (2012), E68, o1366] are corrected.

The angle τ (backbone N—Cα—C) is the most contested Engh and Huber refinement target parameter. It is shown that this parameter is ‘correct’ as a PDB-wide average, but can be improved by taking into account residue types, secondary structures and many other aspects of our knowledge of the biophysical relations between residue type and protein structure.

The Engh and Huber parameters for bond lengths and bond angles have been used uncontested in macromolecular structure refinement from 1991 until very recently, despite critical discussion of their ubiquitous validity by many authors. An extensive analysis of the backbone angle τ (N—Cα—C) illustrates that the Engh and Huber parameters can indeed be improved and a recent study [Tronrud et al. (2010 ▶), Acta Cryst. D66, 834–842] confirms these ideas. However, the present study of τ shows that improving the Engh and Huber parameters will be considerably more complex than simply making the parameters a function of the backbone ϕ, ψ angles. Many other aspects, such as the cooperativity of hydrogen bonds, the bending of secondary-structure elements and a series of biophysical aspects of the 20 amino-acid types, will also need to be taken into account. Different sets of Engh and Huber parameters will be needed for conceptually different refinement programs.

The title compound, [PdCl2(C21H33P)2], forms a monomeric complex with a trans-square-planar coordination geometry about the PdII atom which lies on an inversion centre. The Pd—P bond lengths are 2.3760 (13) Å, while the Pd—Cl bond lengths are 2.3172 (14) Å. The observed structure was found to be closely related to that of trans-dichloridobis[dicyclo­hex­yl(phen­yl)phosphane-κP]palladium(II), [PdCl2{P(C6H11)2(C6H5)}2] [Burgoyne et al. (2012 ▶). Acta Cryst. E68, m404].

The title compound, [Tb(NO3)3(C12H16N3O2)2], was prepared from the nitroxide radical ligand 4,4,5,5-tetra­methyl­-2-(pyridin-2-yl)-imidazoline-1-oxyl-3-oxide and TbIII nitrate. The TbIII ion adopts a doubly-capped square-anti­prismatic coord­ination environment defined by three chelating nitrate anions and two N,O-bidentate nitronyl nitroxide radical ligands. Weak C—H⋯O hydrogen bonds connect the molecules into a three-dimensional framework. The title structure is isotypic with the Ho analogue [Li (2012 ▶). Acta Cryst. E68, 550].

The crystallization and preliminary neutron crystallographic analysis of selectively CH3-protonated deuterated rubredoxin from P. furiosus is presented. This work represents the first reported use of selectively labeled material for phasing applications using neutron protein crystallography.

Neutron crystallography is used to locate H atoms in biological materials and can distinguish between negatively scattering hydrogen-substituted and positively scattering deuterium-substituted positions in isomorphous neutron structures. Recently, Hauptman & Langs (2003 ▶; Acta Cryst. A59, 250–254) have shown that neutron diffraction data can be used to solve macromolecular structures by direct methods and that solution is aided by the presence of negatively scattering H atoms in the structure. Selective-labeling protocols allow the design and production of H/D-labeled macromolecular structures in which the ratio of H to D atoms can be precisely controlled. Methyl selective-labeling protocols were applied to introduce (1H-δ methyl)-leucine and (1H-γ methyl)-valine into deuterated rubredoxin from Pyrococcus furiosus (PfRd). Here, the production, crystallization and preliminary neutron analysis of a selectively CH3-protonated deuterated PfRd sample, which provided a high-quality neutron data set that extended to 1.75 Å resolution using the new LADI-III instrument at the Institut Laue-Langevin, are reported. Preliminary analysis of neutron density maps allows unambiguous assignment of the positions of H atoms at the methyl groups of the valine and leucine residues in the otherwise deuterated rubredoxin structure.

The crystal structure of bis­(2-formyl­phenolato-κ2 O,O′)nickel(II), [Ni(C7H5O2)2], a square-planar centrosymmetric complex, has been reported previously [Li & Chen (2006). Acta Cryst. E62, m1038–m1039]. However, a number of warning signs allows the assumption that the carbonyl group in the salicylaldehydate ligand of the claimed complex is incorrect. The crystal structure was therefore redetermined on basis of the originally deposited structure factors. After substituting the carbonyl O atom by an N atom, the model can be completed with an imine H atom, which was clearly discernible in a difference map. The resulting model, corresponding to bis­[2-(imino­meth­yl)phenolato-κ2 N,O′]nickel(II), [Ni(C7H6NO)2], converges well and none of the previous structural alerts remains. This reinter­pretation is also consistent with the published synthesis, which was carried out using salicylaldehyde in the presence of aqueous NH3. The reinter­preted structure is virtually identical to earlier reports dealing with this bis-iminato NiII complex.

An evaluation of performance of the System for Integrated modeLling of Atmospheric coMposition (SILAM) in application to birch pollen dispersion is presented. The system is described in a companion paper whereas the current study evaluates the model sensitivity to details of the pollen emission module parameterisation and to the meteorological input data. The most important parameters are highlighted. The reference year considered for the analysis is 2006. It is shown that the model is capable of predicting about two-thirds of allergenic alerts, with the odds ratio exceeding 12 for the best setup. Several other statistics corroborate with these estimations. Low-pollen concentration days are also predicted correctly in more than two-thirds of cases. The model experiences certain difficulties only with intermediate pollen concentrations. It is demonstrated that the most important input parameter is the near-surface temperature, the bias of which can easily jeopardise the results. The model sensitivity to random fluctuations of temperature is much lower. Other parameters important at various stages of pollen development, release, and dispersion are precipitation and ambient humidity, as well as wind direction.