Isolation and culture of spinal cord motor neurons

Isolated spinal motoneurons are a powerful tool for studying basic mechanisms of neurite growth and survival. Since motoneurons are a minor population of developing spinal cord cells, they need to be purified and enriched to separate them from non-neuronal cells. Therefore, the particular feature of embryonic motoneurons to express the low affinity neurotrophin receptor p75(NTR) is used to separate the motoneurons from other contaminating cells. Two ways are described to isolate embryonic motoneurons: the basic protocol taking advantage of the ability of p75(NTR) to bind lectin, and an alternative method using an antibody against p75(NTR) for a panning procedure. These protocols comprise suggestions for the cultivation of the isolated motoneurons for experiments regarding neural outgrowth and survival as well as instruction for the preparation of proteins of the cells.

Galaxy evolution. Black hole feedback in the luminous quasar PDS 456

The evolution of galaxies is connected to the growth of supermassive black holes in their centers. During the quasar phase, a huge luminosity is released as matter falls onto the black hole, and radiation-driven winds can transfer most of this energy back to the host galaxy. Over five different epochs, we detected the signatures of a nearly spherical stream of highly ionized gas in the broadband x-ray spectra of the luminous quasar PDS 456. This persistent wind is expelled at relativistic speeds from the inner accretion disk, and its wide aperture suggests an effective coupling with the ambient gas. The outflow's kinetic power larger than 10(46) ergs per second is enough to provide the feedback required by models of black hole and host galaxy coevolution.

A possible close supermassive black-hole binary in a quasar with optical periodicity

Quasars have long been known to be variable sources at all wavelengths. Their optical variability is stochastic and can be due to a variety of physical mechanisms; it is also well-described statistically in terms of a damped random walk model. The recent availability of large collections of astronomical time series of flux measurements (light curves) offers new data sets for a systematic exploration of quasar variability. Here we report the detection of a strong, smooth periodic signal in the optical variability of the quasar PG 1302-102 with a mean observed period of 1,884 ± 88 days. It was identified in a search for periodic variability in a data set of light curves for 247,000 known, spectroscopically confirmed quasars with a temporal baseline of about 9 years. Although the interpretation of this phenomenon is still uncertain, the most plausible mechanisms involve a binary system of two supermassive black holes with a subparsec separation. Such systems are an expected consequence of galaxy mergers and can provide important constraints on models of galaxy formation and evolution.

Syntheses and Structures of 9-Bromo-10-diphenylphosphanylanthracene and its Oxidation Products

Treatment of 9,10-dibromoanthracene with one mole equivalent of n-butyllithium and chlorodiphenylphosphane yields 9-bromo-10-diphenylphosphanylanthracene (1). Oxidation of 1 with chalcogens leads to {Br(C14H8)(Ph2P=E)} with E = O (2), S (3) and Se (4). The syntheses and structure determinations of the parent compound 1 and the oxidized species 2 - 4 are reported.

Polymorphism of Dibromo-tetrakis(tetrahydrofuran-κO)magnesium(II)

The title compound, [MgBr2(C4H8O)4] (1a), forms twinned four-component monoclinic crystals as a new polymorph, space group P21/n with Z´ = 2, in addition to the already known tetragonal polymorph (1b). Although the molecular parameters in the two polymorphs match very well, the packing patterns are significantly different. Furthermore, the correct constitution of the mixed halide bromo-chloro-tetrakis(tetrahydrofuran-κO)magnesium(II) (2) could be determined.

Asymmetries in core-collapse supernovae from maps of radioactive 44Ti in Cassiopeia A

Asymmetry is required by most numerical simulations of stellar core-collapse explosions, but the form it takes differs significantly among models. The spatial distribution of radioactive (44)Ti, synthesized in an exploding star near the boundary between material falling back onto the collapsing core and that ejected into the surrounding medium, directly probes the explosion asymmetries. Cassiopeia A is a young, nearby, core-collapse remnant from which (44)Ti emission has previously been detected but not imaged. Asymmetries in the explosion have been indirectly inferred from a high ratio of observed (44)Ti emission to estimated (56)Ni emission, from optical light echoes, and from jet-like features seen in the X-ray and optical ejecta. Here we report spatial maps and spectral properties of the (44)Ti in Cassiopeia A. This may explain the unexpected lack of correlation between the (44)Ti and iron X-ray emission, the latter being visible only in shock-heated material. The observed spatial distribution rules out symmetric explosions even with a high level of convective mixing, as well as highly asymmetric bipolar explosions resulting from a fast-rotating progenitor. Instead, these observations provide strong evidence for the development of low-mode convective instabilities in core-collapse supernovae.

Quantitative vertebral morphometry based on parametric modeling of vertebral bodies in 3D

Quantitative vertebral morphometry (QVM) was performed by parametric modeling of vertebral bodies in three dimensions (3D).

INTRODUCTION

Identification of vertebral fractures in two dimensions is a challenging task due to the projective nature of radiographic images and variability in the vertebral shape. By generating detailed 3D anatomical images, computed tomography (CT) enables accurate measurement of vertebral deformations and fractures.

METHODS

A detailed 3D representation of the vertebral body shape is obtained by automatically aligning a parametric 3D model to vertebral bodies in CT images. The parameters of the 3D model describe clinically meaningful morphometric vertebral body features, and QVM in 3D is performed by comparing the parameters to their statistical values. Thresholds and parameters that best discriminate between normal and fractured vertebral bodies are determined by applying statistical classification analysis.

RESULTS

The proposed QVM in 3D was applied to 454 normal and 228 fractured vertebral bodies, yielding classification sensitivity of 92.5% at 7.5% specificity, with corresponding accuracy of 92.5% and precision of 86.1%. The 3D shape parameters that provided the best separation between normal and fractured vertebral bodies were the vertebral body height and the inclination and concavity of both vertebral endplates.

CONCLUSION

The described QVM in 3D is able to efficiently and objectively discriminate between normal and fractured vertebral bodies and identify morphological cases (wedge, (bi)concavity, or crush) and grades (1, 2, or 3) of vertebral body fractures. It may be therefore valuable for diagnosing and predicting vertebral fractures in patients who are at risk of osteoporosis.

A rapidly spinning supermassive black hole at the centre of NGC 1365

Broad X-ray emission lines from neutral and partially ionized iron observed in active galaxies have been interpreted as fluorescence produced by the reflection of hard X-rays off the inner edge of an accretion disk. In this model, line broadening and distortion result from rapid rotation and relativistic effects near the black hole, the line shape being sensitive to its spin. Alternative models in which the distortions result from absorption by intervening structures provide an equally good description of the data, and there has been no general agreement on which is correct. Recent claims that the black hole (2 × 10(6) solar masses) at the centre of the galaxy NGC 1365 is rotating at close to its maximum possible speed rest on the assumption of relativistic reflection. Here we report X-ray observations of NGC 1365 that reveal the relativistic disk features through broadened Fe-line emission and an associated Compton scattering excess of 10-30 kiloelectronvolts. Using temporal and spectral analyses, we disentangle continuum changes due to time-variable absorption from reflection, which we find arises from a region within 2.5 gravitational radii of the rapidly spinning black hole. Absorption-dominated models that do not include relativistic disk reflection can be ruled out both statistically and on physical grounds.

Anharmonic motion in experimental charge density investigations

In the charge density study of 9-diphenylthiophosphinoylanthracene the thermal motion of several atoms needed an anharmonic description via Gram-Charlier coefficients even for data collected at 15 K. As several data sets at different temperatures were measured, this anharmonic model could be proved to be superior to a disorder model. Refinements against theoretical data showed the resemblance of an anharmonic model and a disorder model with two positions very close to each other (~0.2 Å), whereas these two models could be clearly distinguished if the second position is 0.5 Å apart. The refined multipole parameters were distorted when the anharmonic motion was not properly refined. Therefore, this study reveals the importance of detecting and properly handling anharmonic motion. Unrefined anharmonic motion leads to typical shashlik-like residual density patterns. Therefore, careful analysis of the residual density and the derived probability density function after the refinement of the Gram-Charlier coefficients proved to be the most useful tools to indicate the presence of anharmonic motion.

The intense starburst HDF 850.1 in a galaxy overdensity at z ≈ 5.2 in the Hubble Deep Field

The Hubble Deep Field provides one of the deepest multiwavelength views of the distant Universe and has led to the detection of thousands of galaxies seen throughout cosmic time. An early map of the Hubble Deep Field at a wavelength of 850 micrometres, which is sensitive to dust emission powered by star formation, revealed the brightest source in the field, dubbed HDF 850.1 (ref. 2). For more than a decade, and despite significant efforts, no counterpart was found at shorter wavelengths, and it was not possible to determine its redshift, size or mass. Here we report a redshift of z = 5.183 for HDF 850.1, from a millimetre-wave molecular line scan. This places HDF 850.1 in a galaxy overdensity at z ≈ 5.2, corresponding to a cosmic age of only 1.1 billion years after the Big Bang. This redshift is significantly higher than earlier estimates and higher than those of most of the hundreds of submillimetre-bright galaxies identified so far. The source has a star-formation rate of 850 solar masses per year and is spatially resolved on scales of 5 kiloparsecs, with an implied dynamical mass of about 1.3 × 10(11) solar masses, a significant fraction of which is present in the form of molecular gas. Despite our accurate determination of redshift and position, a counterpart emitting starlight remains elusive.

Genomic expression libraries for the identification of cross-reactive orthopoxvirus antigens

Increasing numbers of human cowpox virus infections that are being observed and that particularly affect young non-vaccinated persons have renewed interest in this zoonotic disease. Usually causing a self-limiting local infection, human cowpox can in fact be fatal for immunocompromised individuals. Conventional smallpox vaccination presumably protects an individual from infections with other Orthopoxviruses, including cowpox virus. However, available live vaccines are causing severe adverse reactions especially in individuals with impaired immunity. Because of a decrease in protective immunity against Orthopoxviruses and a coincident increase in the proportion of immunodeficient individuals in today's population, safer vaccines need to be developed. Recombinant subunit vaccines containing cross-reactive antigens are promising candidates, which avoid the application of infectious virus. However, subunit vaccines should contain carefully selected antigens to confer a solid cross-protection against different Orthopoxvirus species. Little is known about the cross-reactivity of antibodies elicited to cowpox virus proteins. Here, we first identified 21 immunogenic proteins of cowpox and vaccinia virus by serological screenings of genomic Orthopoxvirus expression libraries. Screenings were performed using sera from vaccinated humans and animals as well as clinical sera from patients and animals with a naturally acquired cowpox virus infection. We further analyzed the cross-reactivity of the identified immunogenic proteins. Out of 21 identified proteins 16 were found to be cross-reactive between cowpox and vaccinia virus. The presented findings provide important indications for the design of new-generation recombinant subunit vaccines.

Reactivity studies of a Ge(I)-Ge(I) compound with and without cleavage of the Ge-Ge bond

This Communication describes two strikingly different reactivities of a digermylene [{PhC(NtBu)(2)}(2)Ge(2)] (1) featuring a Ge(I)-Ge(I) single bond. In the reaction with azobenzene, 1 affords the oxidative addition product LGeN(Ph)N(Ph)GeL [2; L = PhC(NtBu)(2)], with simultaneous cleavage of the Ge-Ge bond, whereas treatment of 1 with Fe(2)(CO)(9) yields the Lewis acid-base adduct LGe[Fe(CO)(4)]Ge[(Fe(CO)(4)]L (3). Both compounds were characterized by single-crystal X-ray diffraction, NMR spectroscopy, electrospray ionization mass spectrometry, and elemental analysis.

Molecular Classification of Normal and Cancer Mammospheres

Introduction: For decades, scientists have attempted to develop models for growing and studying primary tumors outside of the human body. These techniques have ranged from growth assays in immuno-compromised mice to simple monolayer cultures. Unfortunately, these techniques are either too complex and expensive (animal models), or too simple (monolayer cultures) to effectively recapitulate the growth characteristics of human tumors. The recent discovery of cancer stem cells (CSCs) has provided new insight into the reasons that ex-vivo cultures have been unable to provide an accurate model for in-vivo tumors.Hypothesis: Our hypothesis is that three-dimensional mammosphere culture represents a practical means of enriching cancer stem cells and assessing, ex-vivo, the growth characteristics of human breast cancer. We believe this technique will provide a more accurate model system for testing novel drug targets specific for cancer stem cells and tailor specific therapies for patients.Method: By combining ideas from a number of previously described methods, we have recently developed a protocol to grow and maintain breast cancer specimens in a simple three-dimensional culture system using serum-free media, MEGM supplemented with BT-20, insulin, EGF and bFGF. We have successfully cultured both normal and tumor cells from clinical samples as small as a fine needle aspiration. In each case, small subset of epithelial cells from each sample grow into mammospheres.Results: Our preliminary data in characterization of the mammospheres shows that different morphologies and histotypes can be achieved in culture. We are currently using protein expression and transcriptional profiling methods to characterize the cell types within mammospheres and the histotypes of cancer that can generate mammospheres. Using immunofluorescence of a few key protein markers we have found that mammospheres, derived both from normal breast tissue and from tumor tissue samples, express putative stem cells markers as determined by expression of CD44 in the absence of CD24. Only a subset (30-50%) of CD44 positive cells in mammospheres are also positive for ALDH1 in both normal and cancer derived cultures suggesting an undifferentiating population of cells, potentially indicative of the presence of stem cells. Cells in the mammospheres are also positive for both epithelial and myoepithelial markers (e.g. broad-range cytokeratin, CK8, CK5, CK17, vimentin, P63) suggesting variable differentiation potential of progenitor cells. Preliminary transcriptional profiling data suggests that gene sets useful in molecular subtyping of primary tumors may also be informative in mammospheres, and that segregation of profiles of stromal and tumor cells can be elucidated through studies of mammospheres vs. core biopsies.Conclusion: This model system has the potential to be an inexpensive, accurate and robust model for breast cancer. It could help in the understanding of mechanisms of drug resistance, recurrence and metastasis, as well as in predicting treatment success or failure as we move towards personalized medicine.

Citation Information: Cancer Res 2009;69(24 Suppl):Abstract nr 501.

Synthesis and structural characterization of aluminum iminophosphonamide complexes

Monoanionic iminophosphonamide ligands have a N-P-N linkage and undergo four-membered ring N,N-ligand formation when treated with aluminum compounds. The reaction of LLi (L = [Ph(2)P(NSiMe(3))(2)]) with equivalent amounts of AlCl(3) and AlMeCl(2) in toluene afforded LAlCl(2) (3) and LAlClMe (4), respectively. L(2)AlH (5), LAlEt(2) (6), and LAl(NMe(2))(2) (7) respectively were prepared by the reaction of LH with AlH(3) x NMe(3), AlEt(3), and Al(NMe(2))(3) in n-hexane. Subsequently compounds 3-7 were characterized by elemental analysis, (1)H, (13)C, and (31)P NMR spectroscopy and X-ray crystallographic studies (for 3, 4, 5, and 7).

6-Benzyl-3,4-dimeth-oxy-10-methyl-pyrido[2',1':2,3]imidazo[4,5-c]isoquinolin-5(6H)-one

Pyrido[2′,1′:2,3]imidazo[4,5-c]isoquinolin-5(6H)-ones such as the title compound, C₂₄H₂₁N₃O₃, can be obtained in a few minutes in a microwave-assisted three-component reaction from 2-amino­pyridines, isocyanides and 2-carboxy­benz­aldehydes. In the title compound, the pyrido[2′,1′:2,3]imidazo[4,5-c]isoquinolin-5(6H)-one ring system is almost planar (mean deviation 0.068 Å). The dihedral angle between the benzyl ring and the pyrido[2′,1′:2,3]imidazo[4,5-c]isoquinolin-5(6H)-one ring system is 78.2°. The crystal structure is stabilized by inter­molecular C—H⋯O and C—H⋯N hydrogen bonds.

A comparison of a microfocus X-ray source and a conventional sealed tube for crystal structure determination

Experiments are described in which a direct comparison was made between a conventional 2 kW water-cooled sealed-tube X-ray source and a 30 W air-cooled microfocus source with focusing multilayer optics, using the same goniometer, detector, radiation (Mo Kα), crystals and software. The beam characteristics of the two sources were analyzed and the quality of the resulting data sets compared. The Incoatec Microfocus Source (IµS) gave a narrow approximately Gaussian-shaped primary beam profile, whereas the Bruker AXS sealed-tube source, equipped with a graphite monochromator and a monocapillary collimator, had a broader beam with an approximate intensity plateau. Both sources were mounted on the same Bruker D8 goniometer with a SMART APEX II CCD detector and Bruker Kryoflex low-temperature device. Switching between sources simply required changing the software zero setting of the 2θ circle and could be performed in a few minutes, so it was possible to use the same crystal for both sources without changing its temperature or orientation. A representative cross section of compounds (organic, organometallic and salt) with and without heavy atoms was investigated. For each compound, two data sets, one from a small and one from a large crystal, were collected using each source. In another experiment, the data quality was compared for crystals of the same compound that had been chosen so that they had dimensions similar to the width of the beam. The data were processed and the structures refined using standard Bruker andSHELXsoftware. The experiments show that the IµS gives superior data for small crystals whereas the diffracted intensities were comparable for the large crystals. Appropriate scaling is particularly important for the IµS data.