Revealing Three-Dimensional Structure of an Individual Colloidal Crystal Grain by Coherent X-Ray Diffractive Imaging.

We present results of a coherent x-ray diffractive imaging experiment performed on a single colloidal crystal grain. The full three-dimensional (3D) reciprocal space map measured by an azimuthal rotational scan contained several orders of Bragg reflections together with the coherent interference signal between them. Applying the iterative phase retrieval approach, the 3D structure of the crystal grain was reconstructed and positions of individual colloidal particles were resolved. As a result, an exact stacking sequence of hexagonal close-packed layers including planar and linear defects were identified.

[New Approach to the Mitotype Classification in Black Honeybee Apis mellifera mellifera and Iberian Honeybee Apis mellifera iberiensis].

The black honeybee Apis mellifera mellifera L. is today the only subspecies of honeybee which is suitable for commercial breeding in the climatic conditions of Northern Europe with long cold winters. The main problem of the black honeybee in Russia and European countries is the preservation of the indigenous gene pool purity, which is lost as a result of hybridization with subspecies, A. m. caucasica, A. m. carnica, A. m. carpatica, and A. m. armeniaca, introduced from southern regions. Genetic identification of the subspecies will reduce the extent of hybridization and provide the gene pool conservation of the black honeybee. Modern classification of the honeybee mitotypes is mainly based on the combined use ofthe DraI restriction endonuclease recognition site polymorphism and sequence polymorphism of the mtDNA COI-COII region. We performed a comparative analysis of the mtDNA COI-COII region sequence polymorphism in the honeybees ofthe evolutionary lineage M from Ural and West European populations of black honeybee A. m. mellifera and Spanish bee A. m. iberiensis. A new approach to the classification of the honeybee M mitotypes was suggested. Using this approach and on the basis of the seven most informative SNPs of the mtDNA COI-COII region, eight honeybee mitotype groups were identified. In addition, it is suggested that this approach will simplify the previously proposed complicated mitotype classification and will make it possible to assess the level of the mitotype diversity and to identify the mitotypes that are the most valuable for the honeybee breeding and rearing.

[Molecular genetic analysis of five extant reserves of black honeybee Apis melifera melifera in the Urals and the Volga region].

Local populations of the black honeybee Apis mellifera mellifera from the Urals and the Volga region were examined in comparison with local populations of southern honeybee subspecies A. m. caucasica and A. m. carpatica from the Caucasus and the Carpathians. Genetic analysis was performed on the basis of the polymorphism of nine microsatellite loci of nuclear DNA and the mtDNA COI­COII locus. On the territory of the Urals and the Volga region, five extant populations (reserves) of the black honeybee A. m. mellifera were identified, including the Burzyanskaya, Tatyshlinskaya, Yuzhno-Prikamskaya, Visherskaya, and Kambarskaya populations. These five populations are the basis of the modern gene pool of the black honeybee A. m. mellifera from the Urals and the Volga region. The greatest proportion of the remaining indigenous gene pool of A. m. mellifera (the core of the gene pool of the population of A. m. mellifera) is distributed over the entire territory of Perm krai and the north of the Republic of Bashkortostan. For the population of A. m. mellifera from the Urals and the Volga region, the genetic standards were calculated, which will be useful for future population studies of honeybees.

[Genetic Differentiation of Local Populations of the Dark European Bee Apis mellifera mellifera L. in the Urals].

For the last two centuries, beekeepers in Russia and Europe have been introducing bees from the southern regions to the northern ones, subjecting the genetic pool of the dark European bee Apis mellifera mellifera L. subspecies to extensive hybridization. In order to reconfirm on the genetic level the previously published morphological data on the native bee population in the Urals, the Bashkortostan Republic, and the Perm Krai, we analyzed the polymorphism of the mitochondrial (mtDNA COI-COII intergenic locus) and nuclear (two microsatellite loci, ap243 and 4a110) DNA markers. Four local populations of the dark European bee A. m. mellifera surviving in the Urals have been identified, and their principal genetic characteristics have been determined. Data on the genetic structure and geographical localization of the areals of the dark European bee local populations in the Urals may be of use in restoring the damaged genetic pool of A. m. mellifera in Russia and other northern countries.

[NEGATIVE REGULATORS OF TUMOR SUPPRESSOR P53 IN THE CONTEXT OF ANTICANCER THERAPY].

P53 protein is considered to be the major tumor suppressor in human cells. Cancer cells do not survive if the p53-mediated signaling pathways function properly. However, about half of all malignancies still express wild type p53. One of the explanations to this is that p53 is suppressed by overexpression of p53-specific E3-ubiquitin ligases: Mdm2, MdmX, Pirh2 and Cop1. Pharmacological inhibition of protein-protein interactions between p53 and these negative regulators is a promising therapeutic approach to treat cancers retaining wild type p53. To date, a series of chemical inhibitors of p53 interactions with Mdm2 and MdmX E3-ubiquitin ligases have been discovered and characterized. Several of them are in the early stages of clinical trials. Despite this fact, their clinical efficacy may be hampered by a number of reasons, including tumor-specific expression of multiple isoforms of the target E3-ligases, which become inert to treatment with small molecules. This and other biochemical mechanisms of possible resistance of tumor cells with wild type p53 to small molecules against its negative regulators will be discussed in this review.

[TUMOR SUPPRESSOR p63 REGULATES EXPRESSION OF UBIQUITIN LIGASE Pirh2].

Transcription factor p63 is a member of the p53 protein family. Due to the high degree of structural similarity p53, p63, and p73 are known to have overlapping functions relating to cell cycle regulation, apoptosis and tumor transformation. Furthermore, p63 plays crucial role in epidermal tissue development and differentiation. Pirh2 (product of RCHY1 gene) is an E3 ubiquitin ligase modifying all three members of the p53 family resulting in their subsequent proteasomal degradation. Our results demonstrate that p63, similar to p53, is able to regulate expression levels of Pirh2. Importantly, Pirh2 expression is activated only by transcriptionally active isoform of p63--TAp63, but not the N-terminally truncated ΔNp63.

[Radiofrequency obliteration of veins in surgical treatment of varicose disease].

OBJECTIVES: 1) To show the role and place of endovenous radiofrequency obliteration (RFO) in removing the vertical reflux in the varicose major superficial large-diameter veins. 2) To assess the outcomes of treatment of patients with varicose disease and to determine their correlation with the scales VCSS, VSDS and CEAP. MATERIAL AND METHODS: Endovascular methods, the technique of endovascular radiofrequency (RFO) ClosureFAST belongs to, are intended to within the shortest terms remove reflux without disturbing the patient's habitual way of life and along with it to improve the main aspects of quality of life.From 2009 to 2011, we operated on 110 patients (a total of 135 extremities). The mean age amounted to 41 years. Patients with an ostium-adjacent venous diameter of less than 1.3 cm were excluded from the sample, 37% of patients had various trophic impairments, 41% of patients had various concomitant somatic pathology, and 17% of patients had the body weight index (BWI) exceeding 30. Diagnosis and severity of the disease were formed with due regard for the scales of disease severity VCSS, VSDS and CEAP, as well as the worked out diagnostic algorithm. The venous status was evaluated by the findings of the objective examination and triplex angioscanning. The groups of patients with reflux along the altered venous segments were distributed as follows: 32.6% of patients - the superior vena cava with the classical course, 8% - the inferior vena cava, 7% - vein of Giacomini, 16% - the anterior accessory vein, 8% - the anterior lateral inflow, 28.4% - the extrafascial course of the vessel. The pain factor according to the analogue scale amounted to 0.8. In the postoperative period, the patients were followed up and examined on day 3, day 10 and then after 1, 3, 6, 12 months and more. RESULTS: RFO was successfully used in patients in all venous basins irrespective of the diameter and anatomical course of the venous structures. In 98% of cases we managed to achieve occlusion with the removal of the reflux within the terms of up to one year. Regress of clinical symptoms and improvement of quality of life were reflected in the VCSS. 100% of patients returned to the habitual activity on the day of operation. CONCLUSION: RFO with obvious efficacy may be used in various topographical areas of lower limbs regardless of the veins' diameter and their anatomical course. RFO is a method of choice in patients with high BMI and accompanying somatic pathology. Ambulatory follow up of patients with severe somatic pathology is possible, independently of decompensation of venous pathology. Clinical scales of the disease severity VCSS and VSDS are convenient in use, clearly reflecting the dynamics of the disease in the pre- and postoperative periods, which makes it possible to recommend them for wide application along with other scales on studying quality of life.

[Endovasal obliteration of the main subcutaneous veins - a mechanism of action].

Active dissemination implementation of endovascular methods has during the past decade been a progressive tendency of the development of surgical treatment management of varicose disease.Amongst these methods, endovasal laser obliteration in Russia occupies the leading place. Despite widespread implementation of this method into clinical practice still there are neither common concepts on the mechanisms of action of laser energy, inducing lesions of the venous wall followed by obliteration, nor, consequently,criteria for administration thereof The search for an optimal method and mode of intravascular intervention is based on study-ing the mechanisms of the damaging action of laser energy on the venous wall. The article contains a literature review of the studies dedicated to investigating the mechanisms of action of endovasal methods of treatment for varicose disease.

Variable dislocation widths in colloidal crystals of soft thermosensitive spheres.

We report on detailed measurements of the core structure of Shockley partial dislocations in colloidal crystals. In crystalline arrays of micrometer sized thermosensitive particles, the interactions between the colloidal building blocks were tuned by changing the temperature. Individual dislocation cores were observed in a confocal microscope and their behavior as a function of temperature was studied. The obtained results qualitatively agree with the Peierls theory and are promising for further studies in which both Peierls stress and dislocation core width are measured simultaneously.

Experimental observation of fractionated crystallization in polydisperse platelike colloids.

We have discovered that the long-term aging of the hexagonal columnar liquid-crystal phase of polydisperse gibbsite platelets leads to fractionated crystallization, that is, to the formation of coexisting columnar crystals with different periods. This process was revealed by microradian X-ray diffraction demonstrating the splitting of the Bragg intercolumnar reflections into sequences of sharper reflections. The fractionated crystallization was observed in a number of samples of sterically stabilized as well as charge-stabilized polydisperse gibbsite platelets.

Scattering from colloidal cubic silica shells: Part I, particle form factors and optical contrast variation.

HYPOTHESIS: Colloidal cubic silica shells, prepared from cuprous oxide cubes, with a typical size of 100 nm are promising model particles for scattering studies on dilute, as well as concentrated fluids, of non-spherical colloids. EXPERIMENTS: Small angle X-ray scattering, and static light scattering are employed to determine form factors of cubic silica shells and silica covered cuprous oxide cubes. Contrast variation experiments are performed to assess the refractive index and optical homogeneity of the cubic silica shells, which is important for the extension of the scattering study to concentrated dispersions of cubic shells in Part II (Dekker, submitted for publication). RESULTS: The experimental form factors, which compare well to theoretical form factors, manifest cubic silica shells that are dispersed as single stable colloids with a shape intermediate between a sphere and a perfect cube. Contrast variation demonstrates that the silica shells are optically homogeneous, with a refractive index that is independent of the shell thickness. The results presented here open up the possibility to extract structure factors from light scattering measurements on concentrated cube dispersions in Part II.

Experimental realization of biaxial liquid crystal phases in colloidal dispersions of boardlike particles.

Biaxial nematic and biaxial smectic phases were found in a colloidal model system of goethite (alpha-FeOOH) particles with a simple boardlike shape and short-range repulsive interaction. The macroscopic domains were oriented by a magnetic field and their structure was revealed by small angle x-ray scattering. In accordance with theoretical predictions, biaxiality appears in a system with particles that have a shape almost exactly in between rodlike and platelike. Our results suggest that biaxial phases can be readily obtained by a proper choice of the particle shape.

Influence of polydispersity on the phase behavior of colloidal goethite.

The effect of fractionation on the phase behavior of colloidal goethite dispersions with different polydispersities (17%, 35%, and 55% in length) has been studied by small angle x-ray scattering and transmission electron microscopy. All systems show at least nematic and smectic phases. The occurrence of the latter phase at such a high polydispersity is remarkable. It is shown that in the highly polydisperse systems strong fractionation occurs, which is able to reduce the local length polydispersity up to a factor of 2. A columnar phase was only found in the 35% and 55% polydisperse systems. It seems that the columnar phase accommodates the particles that do not fit into the smectic layers and, thus, reduces the length polydispersity within the smectic phase even further. The fact that a columnar phase was not found in the system of lowest polydispersity indicates that the smectic phase is the most stable phase at higher concentrations.

Monte Carlo simulations of in-plane stacking disorder in hard-sphere crystals.

On-lattice Monte Carlo simulations of colloidal random-stacking hard-sphere colloidal crystals are presented. The model yields close-packed crystals with random-stacking hexagonal structure. We find a significant amount of in-plane stacking disorder, which slowly anneals in the course of the simulation. The in-plane stacking disorder leads to lateral broadening of the stacking-disorder-induced Bragg rods. It is found that not only the scattering intensity, but also the width is modulated along the Bragg rods.

Study of petrolatum structure: Explaining its variable rheological behavior.

The rheological properties of petrolatum are dependent on both temperature and thermal history. How this thermal dependency can be explained is unclear. In the past it has been suggested that the structure of petrolatum consists of a three-dimensional crystalline network. This has been established using old microscopic techniques only. Therefore a study on the microstructure of petrolatum was conducted using rheometry, DSC, pulsed NMR, polarized light microscopy and synchrotron X-ray. The combination of these techniques show that petrolatum is composed of 21% solid material at room temperature. This consists of partly crystalline lamellar sheets which are packed in stacks. The occurrence of these lamellar sheets is temperature dependent and the number of lamellar stacks is dependent on thermal history. It was shown that rheological differences in petrolatum can be explained by the number of lamellar stacks present, where more lamellar stacks result in more rigid petrolatum.

Molecular Approaches to Safe and Controlled Engineered T-cell Therapy.

Chimeric antigen receptor-modified T-cell therapy (CAR-T therapy) is one of the fastest developing areas of immuno-oncology. Over the past decade, it has revolutionized the cell therapy modality and expedited its pace of development, from optimization of the structure of chimeric antigen receptors and animal model experiments to successful clinical application. The initial designs of the CAR configuration focused on increasing T-cell activation, cytotoxicity, and persistence. However, the first attempts to treat patients with CAR T cells have demonstrated the need for increased safety and controlled activation of genetically modified T cells. Herein, we summarize the different molecular approaches to engineering chimeric antigen receptors for reducing the potential clinical risks of T-cell therapy.

Diffraction based Hanbury Brown and Twiss interferometry at a hard x-ray free-electron laser.

X-ray free-electron lasers (XFELs) provide extremely bright and highly spatially coherent x-ray radiation with femtosecond pulse duration. Currently, they are widely used in biology and material science. Knowledge of the XFEL statistical properties during an experiment may be vitally important for the accurate interpretation of the results. Here, for the first time, we demonstrate Hanbury Brown and Twiss (HBT) interferometry performed in diffraction mode at an XFEL source. It allowed us to determine the XFEL statistical properties directly from the Bragg peaks originating from colloidal crystals. This approach is different from the traditional one when HBT interferometry is performed in the direct beam without a sample. Our analysis has demonstrated nearly full (80%) global spatial coherence of the XFEL pulses and an average pulse duration on the order of ten femtoseconds for the monochromatized beam, which is significantly shorter than expected from the electron bunch measurements.

Dipolar structures in magnetite ferrofluids studied with small-angle neutron scattering with and without applied magnetic field.

Field-induced structure formation in a ferrofluid with well-defined magnetite nanoparticles with a permanent magnetic dipole moment was studied with small-angle neutron scattering (SANS) as a function of the magnetic interactions. The interactions were tuned by adjusting the size of the well-defined, single-magnetic-domain magnetite (Fe3O4) particles and by applying an external magnetic field. For decreasing particle dipole moments, the data show a progressive distortion of the hexagonal symmetry, resulting from the formation of magnetic sheets. The SANS data show qualitative agreement with recent cryogenic transmission electron microscopy results obtained in 2D [Klokkenburg, Phys. Rev. Lett. 97, 185702 (2006)] on the same ferrofluids.

[Local honeybee (Apis mellifera mellifera L.) populations in the Urals].

The COI-COII intergenic region of mitochondrial DNA (mtDNA) was studied in local honeybee (Apis mellifera mellifera) L. populations from the Middle and Southern Urals. Analysis of bee colonies in these regions revealed apiaries enriched in families descending from A. m. mellifera in the maternal lineage. These results confirm the suggestion of preservation of A. m. mellifera refuges in the Urals and provide grounds for work on the preservation of the gene pool of this bee variety, valuable for all Russia.

Magnetic-field-induced orientational order in the isotropic phase of hard colloidal platelets.

The magnetic-field-induced orientational order in the isotropic phase of colloidal gibbsite [Al(OH)3] platelets is studied by means of optical birefringence and small-angle x-ray scattering (SAXS) techniques. The suspensions display field-induced ordering at moderate field strengths (a few Tesla), which increases with increasing particle concentration. The gibbsite particles align their normals perpendicular to the magnetic field and hence possess a negative anisotropy of their diamagnetic susceptibility Delta(chi). The results can be described following a simple, Onsager-like approach. A simplified model is derived that allows one to obtain the orientational distribution function directly from the scattering data. However, it leads to an underestimate of the diamagnetic susceptibility anisotropy Delta(chi). This accounts for the difference between the Delta(chi) values provided by the two experimental techniques (SAXS and magneto-optics). The order of magnitude Delta(chi) approximately 10(-22) J/T(2) lies in between that of goethite suspensions and that of suspensions of organic particles.