Exact propagators for SUSY partners

Pairs of SUSY partner Hamiltonians are studied which are interrelated by usual (linear) or polynomial supersymmetry. Assuming the model of one of the Hamiltonians as exactly solvable with known propagator, expressions for propagators of partner models are derived. The corresponding general results are applied to "a particle in a box", the Harmonic oscillator and a free particle (i.e. to transparent potentials).Comment: 31 page

Functional properties of the Su(Hw) complex are determined by its regulatory environment and multiple interactions on the Su(Hw) protein platform

The Su(Hw) protein was first identified as a DNA-binding component of an insulator complex in Drosophila. Insulators are regulatory elements that can block the enhancer-promoter communication and exhibit boundary activity. Some insulator complexes contribute to the higher-order organization of chromatin in topologically associated domains that are fundamental elements of the eukaryotic genomic structure. The Su(Hw)-dependent protein complex is a unique model for studying the insulator, since its basic structural components affecting its activity are already known. However, the mechanisms involving this complex in various regulatory processes and the precise interaction between the components of the Su(Hw) insulators remain poorly understood. Our recent studies reveal the fine mechanism of formation and function of the Su(Hw) insulator. Our results provide, for the first time, an example of a high complexity of interactions between the insulator proteins that are required to form the (Su(Hw)/Mod(mdg4)-67.2/CP190) complex. All interactions between the proteins are to a greater or lesser extent redundant, which increases the reliability of the complex formation. We conclude that both association with CP190 and Mod(mdg4)-67.2 partners and the proper organization of the DNA binding site are essential for the efficient recruitment of the Su(Hw) complex to chromatin insulators. In this review, we demonstrate the role of multiple interactions between the major components of the Su(Hw) insulator complex (Su(Hw)/Mod(mdg4)-67.2/CP190) in its activity. It was shown that Su(Hw) may regulate the enhancer–promoter communication via the newly described insulator neutralization mechanism. Moreover, Su(Hw) participates in direct regulation of activity of vicinity promoters. Finally, we demonstrate the mechanism of organization of “insulator bodies” and suggest a model describing their role in proper binding of the Su(Hw) complex to chromatin

CARDIOVASCULAR RISK FACTORS IN PATIENTS WITH OBSTRUCTIVE SLEEP APNEA SYNDROME

The paper analyzes the cause-and-effect relations of obstructive sleep apnea syndrome (OSAS) and cardiovascular diseases (CVD). In OSAS,there is activation of the sympathetic nervous system and proinflammatory and procoagulant systems, endothelial dysfunction, and accelerated atherosclerosis in response to intermittent hypoxia and sleep fragmentation, which leads to increased risk for CVD. Continuous positive airway pressure therapy reduces the risk of death in patients with OSAS</p

Neutralization mechanism of a highly potent antibody against Zika virus

The rapid spread of Zika virus (ZIKV), which causes microcephaly and Guillain-Barré syndrome, signals an urgency to identify therapeutics. Recent efforts to rescreen dengue virus human antibodies for ZIKV cross-neutralization activity showed antibody C10 as one of the most potent. To investigate the ability of the antibody to block fusion, we determined the cryoEM structures of the C10-ZIKV complex at pH levels mimicking the extracellular (pH8.0), early (pH6.5) and late endosomal (pH5.0) environments. The 4.0 Å resolution pH8.0 complex structure shows that the antibody binds to E proteins residues at the intra-dimer interface, and the virus quaternary structure-dependent inter-dimer and inter-raft interfaces. At pH6.5, antibody C10 locks all virus surface E proteins, and at pH5.0, it locks the E protein raft structure, suggesting that it prevents the structural rearrangement of the E proteins during the fusion event—a vital step for infection. This suggests antibody C10 could be a good therapeutic candidate

Gamma Knife stereotactic radiosurgery for intraocular retinoblastoma: a 5-year experience

External beam radiotherapy (EBR) remained for a long time the only method of treatment in children with recurrent and resistant retinoblastoma (RB). This method often leads to serious complications, including the occurrence of secondary malignant tumors. Currently, EBR is used as second-line (salvage) therapy. There is no data in the literature of using Gamma Knife stereotactic radiosurgery (GKRS) in RB treatment.Purpose. To present 5-year experience of using GKRS in patients with RB.Material and methods. 16 children (17 eyes) were treated using GKRS in the period from 2015 to 2019. Mean patient age was 34.7 months (range, 12–114 months). The eyes were classified as group B (n=4), C (n=1), D (n=12). 3 children had the last eye. All patients received systemic and local chemotherapy, all types of local treatment modalities before using GKRS. Recurrent and resistant RB was the indication for GKRS. Marginal 50% mean dose was 22 Gу (range, 20–24 Gу), depending on tumour type and location. Radiation doses were evaluated accounting critical eye structures and the orbit bones.Results. Complete regression was achieved in 11 patients, partial in 2. Four patients underwent enucleation after GKRS. Indications for enucleation were retinoblastoma recurrence (n=2) and vitreous hemorrhage with total retinal detachment (n=2). 13 eyes were salvaged with no signs of keratopathy, uveitis or damage of orbital and surrounding tissues during mean follow-up 30.6 months (range, 7–60 months). Сomplications of different severity occurred in 13 patients, including vitreous hemorrhage in 6 patients, which was successfully treated both conservative (n=3) and using pars plana vitrectomy with simultaneous melphalan irrigation (n=3).Conclusion. The first experience of GKRS as an alternative to enucleation in patients with RB was proved to be reasonable and successful

Using CAST-test to investigate human specific hypersensitivity to the anthrax pathogen

We present the results of applying functional cytometric test of antigen-stimulated activation basophils to assess specific immunological reactivity in the people with anthrax, and immunized with anthrax vaccine. As a criterion for antigen-specific basophil activation, we measured expression of the CD63 membrane receptor, which reflects the process of anaphylactic basophil degranulation. To determine spontaneous and antigen-induced activation of basophils (CCR3+CD63+), a FlowCAST reagent kit (Buhlmann laboratories AG, Switzerland) was used. Anthraxin, an experimental anthrax allergen (a hydrolysate the Bacillus anthracis STI-1 strain), manufactured by the Stavropol Anti-Plague Institute, was used as a specific antigen. As based on clinical and experimental data, a threshold value of &gt; 10% of anthraxin-activated (CCR3+CD63+) basophils was accepted for the in vitro immunodiagnostic CAST test, as a laboratory criterion for the subjects exhibiting specific immune response, i.e., IgE-mediated sensitization. It was shown that, in anthrax patients within one week after onset of the disease (3-7 days), a positive CAST result was obtained in 92.3% cases; the levels of specific basophil activation with anthraxin averaged 37.9% (12.01 ÷ 78.9%). Immunological examination of individuals three weeks (21 days) after vaccination against anthrax revealed CAST-positivity in all the vaccinated persons. Intensity of anthraxin-induced basophil activation the vaccinated subjects was ranged from 10.87 to 30.03%, averaging 17.86%. The overall values of spontaneous and specific activation ranged within 12.39 ÷ 41.46%. The study opens prospectives for implementation of basophil antigenic activation test in the Flow CAST format in diagnostics of anthrax and to identify specific immune rearrangements after vaccination in humans, as an index of actual vaccination rates. Usage of CAST test with anthraxin makes it possible to identify anthrax patients at the early stages (2-4 days after onset of the disease) including, among patients with an increased CCR3+CD63+ background values, evaluation of immunological efficiency in the cohorts at risk for vaccination. At the same time, it was found that a significant decrease in diagnostic sensitivity of CAST test could be observed in the patients immune to anthrax pathogen who received intensive antibacterial and pathogenetic therapy at the early stages of infection, including glucocorticosteroids (anti-inflammatory drugs) and desensitizing agents that inhibit the degree of hypersensitivity development and its expression

STUDYING DEVELOPMENT OF POST-VACCINAL CELLULAR IMMUNITY AGAINST BRUCELLOSIS BY MEANS OF LYMPHOCYTE <i>IN VITRO</i> TESTS USING AN EXPERIMENTAL ANTIGENIC COMPLEX

Regulatory framework and methodological approaches to evaluation of immunological effects of vaccination against brucellosis are not established, and the degree of immunological post-vaccinal rearrangement is not yet developed. Due to leading role of cellular immunity in formation of immune protection against brucellosis, evaluation the cellular response in response to antigenic stimulation may be considered the most informative and objective approach to analysis of immune changes in the body during vaccination. In order to develop the most diagnostically informative methods for design of antigen-stimulation cell tests in vitro, a careful selection of a stimulating agent (antigen) is required, which should have a sufficient activating potential, thus providing specificity of reaction under in vitro conditions. The aim of the present study is to study the in vitro specific activity of a protein-polysaccharide antigenic complex from the Brucella abortus 19 BA strain (BrAg), and an opportunity of its application in order to assess the formation of post-vaccinal cellular immunity against brucellosis.The study was performed with white laboratory mice (n = 50) immunized with the Brucella abortus 19 BA strain. The control group (n = 50) consisted of laboratory mice that received a sterile saline solution in a volume of 0.5 ml. Blood samples were taken from immunized and control animals before vaccination, and 7, 14, 21, and 30 days after immunization. By means of flow cytometry, the activation molecules CD25, CD69, MHC II and CD95, expressed on T lymphocytes (CD3+CD69+, CD3+CD25+, CD3+CD95+, CD3+MHC+) were determined. To observe the development of immunity, the intensity of expression of T lymphocyte activation markers was calculated using the stimulation quotient. BrAg was used for specific in vitro stimulation of T lymphocytes. The liquid brucellosis allergen (brucellin) was used as an antigen for comparison, when studying opportunity of BrAg usage for assessing the postvaccinal immunity development.The following results were obtained: BrAg has pronounced specific activity, it did not cause non-specific in vitro reactions (activation) of T lymphocytes, thus enabling its application as a test antigen when evaluating development of adaptive vaccine immunity against brucella.Experimental testing of brucellosis antigen for carrying out the in vitro antigen-stimulated cellular reactions, aiming for evaluation of post-vaccinal immunity development against brucellosis, showed that the usage of BrAg promotes increase in diagnostic sensitivity of cellular reactions under in vitro experimental conditions. The applied experimental antigen is a quite promising tool for development of laboratory algorithms for brucellosis diagnostics, and assessment of actual vaccination efficiency in cohorts previously vaccinated against brucellosis

Morphogenesis of the T4 tail and tail fibers

Remarkable progress has been made during the past ten years in elucidating the structure of the bacteriophage T4 tail by a combination of three-dimensional image reconstruction from electron micrographs and X-ray crystallography of the components. Partial and complete structures of nine out of twenty tail structural proteins have been determined by X-ray crystallography and have been fitted into the 3D-reconstituted structure of the "extended" tail. The 3D structure of the "contracted" tail was also determined and interpreted in terms of component proteins. Given the pseudo-atomic tail structures both before and after contraction, it is now possible to understand the gross conformational change of the baseplate in terms of the change in the relative positions of the subunit proteins. These studies have explained how the conformational change of the baseplate and contraction of the tail are related to the tail's host cell recognition and membrane penetration function. On the other hand, the baseplate assembly process has been recently reexamined in detail in a precise system involving recombinant proteins (unlike the earlier studies with phage mutants). These experiments showed that the sequential association of the subunits of the baseplate wedge is based on the induced-fit upon association of each subunit. It was also found that, upon association of gp53 (gene product 53), the penultimate subunit of the wedge, six of the wedge intermediates spontaneously associate to form a baseplate-like structure in the absence of the central hub. Structure determination of the rest of the subunits and intermediate complexes and the assembly of the hub still require further study

Cryo-EM structure of an antibody that neutralizes dengue virus type 2 by locking E protein dimers

There are four closely-related dengue virus (DENV) serotypes. Infection with one serotype generates antibodies that may cross-react and enhance infection with other serotypes in a secondary infection. We demonstrated that DENV serotype 2 (DENV2)–specific human monoclonal antibody (HMAb) 2D22 is therapeutic in a mouse model of antibody-enhanced severe dengue disease. We determined the cryo–electron microscopy (cryo-EM) structures of HMAb 2D22 complexed with two different DENV2 strains. HMAb 2D22 binds across viral envelope (E) proteins in the dimeric structure, which probably blocks the E protein reorganization required for virus fusion. HMAb 2D22 “locks” two-thirds of or all dimers on the virus surface, depending on the strain, but neutralizes these DENV2 strains with equal potency. The epitope defined by HMAb 2D22 is a potential target for vaccines and therapeutics