Luminescent coordination polymers based on Ca²⁺ and octahedral cluster anions [{M₆Clⁱ₈}Clᵃ₆}²⁻ (M = Mo, W) : synthesis and thermal stability studies

Luminescent coordination polymers (CPs) based of inexpensive stable precursors are attractive materials for applications. Here we report the synthesis and evaluation of the stability and photophysical characteristics of the first examples of phosphorescent CPs based on octahedral molybdenum and tungsten cluster anions. Specifically 1D CP trans-[{Ca(OPPh₃)₄}{{M₆Clⁱ₈}Clᵃ₆}]∞ (M = Mo, W) can be obtained either directly at increased temperature or via intermediate phases [cis-Ca(OPPh₃)₄(H₂O)₂][{M₆Clⁱ₈}Clᵃ₆]∙2CH₃CN that are stable at room-temperature, but convert to the titled CP at temperatures above 100 °C

Cellular internalisation, bioimaging and dark and photodynamic cytotoxicity of silica nanoparticles doped by {Mo₆I₈}⁴⁺ metal clusters

Silica nanoparticles (SNPs) doped by hexanuclear molybdenum cluster complexes [{Mo₆X₈}L₆]n (X = Cl, Br, or I; L = various inorganic or organic ligands) have been recently suggested as materials with a high potential for biomedical applications due to both the outstanding photoluminescent properties and the ability to efficiently generate singlet oxygen upon photoirradiation. However, no studies were undertaken so far to prove this concept. Therefore, here we examined the potential of photoluminescent SNPs doped by {Mo₆I₈}⁴⁺ for such applications as bioimaging and photodynamic therapy using human epidermoid larynx carcinoma (Hep-2) cell line as a model. Our results demonstrated both: (i) significant luminescence from cells with internalised molybdenum cluster doped SNPs combined with the low cytotoxicity of particles in the darkness and (ii) significant cytotoxicity of the particles upon photoirradiation. Thus, this research provides strong experimental evidence for high potential of molybdenum cluster doped materials in such biomedical applications as optical bioimaging, biolabeling and photodynamic therapy

Lens connexins α3Cx46 and α8Cx50 interact with zonula occludens protein-1 (ZO-1)

Connexin α1Cx43 has previously been shown to bind to the PDZ domain–containing protein ZO-1. The similarity of the carboxyl termini of this connexin and the lens fiber connexins α3Cx46 and α8Cx50 suggested that these connexins may also interact with ZO-1. ZO-1 was shown to be highly expressed in mouse lenses. Colocalization of ZO-1 with α3Cx46 and α8Cx50 connexins in fiber cells was demonstrated by immunofluorescence and by fracture-labeling electron microscopy but showed regional variations throughout the lens. ZO-1 was found to coimmunoprecipitate with α3Cx46 and α8Cx50, and pull-down experiments showed that the second PDZ domain of ZO-1 was involved in this interaction. Transiently expressed α3Cx46 and α8Cx50 connexins lacking the COOH-terminal residues did not bind to the second PDZ domain but still formed structures resembling gap junctions by immunofluorescence. These results indicate that ZO-1 interacts with lens fiber connexins α3Cx46 and α8Cx50 in a manner similar to that previously described for α1Cx43. The spatial variation in the interaction of ZO-1 with lens gap junctions is intriguing and is suggestive of multiple dynamic roles for this association

Lassa virus: characterization of infectious agent, biological models for pathogenesis studies and variants of vaccine

Lassa virus (LASV) is classified into genus Mammarenavirus of Arenaviridae family. This virus is etiological agent of Lassa fever (LF) which is widespread in Africa. On average, in four out of five infected people, LF occurs without symptoms. The annual incidence ranges from 100,000 to 500,000 registered clinical cases, at a mortality rate of 1-2%. Among hospitalized patients with severe symptoms of hemorrhagic fever, this figure may be from 14 to 89.5%. Signs of an adverse outcome in LF are open bleeding and disorders of CNS (convulsions, tremor, disorientation and coma). Death occurs from multiple organ failure. Severely ill people recover slowly and may have relapses and complications such as pneumonia, myocarditis, psychosis, and hearing loss.Transmission of the virus in endemic territories occurs by alimentary way, air-dust and airborne droplets from a zoonotic source – rodents of the species African multimammate rat (Mastomys natalensis), by accidental contacts of people with their secretions (urine, feces, saliva) as well as when butchering carcasses and eating rodents. These animals are characterized by asymptomatic carrier and life-long persistence of the virus. Cases of transmission of the virus from person to person through the blood or other body fluids of patients are described. A sick person is contagious for two months, because the virus circulates in the blood despite high levels of antibodies. Infection of medical staff occurs during emergency surgical operations, or when the rules of contact precautions are not observed. Currently, with the ongoing LF outbreak in Nigeria, since 2016, hospitals have registered mortality rates of 22 and 8% for patients and health workers, respectively. During 1969-2016, 33 imported cases of this disease were described from West Africa to non-endemic territories (in the USA, Canada, Great Britain, the Netherlands, Germany, Israel and Japan). The mortality rate among these patients was 39%.The lack of prophylactic vaccines and specific therapeutic drugs is the major challenge for the prevention of LF. Thus, this review considers biological models (cell cultures and animals) that are suitable for studying the pathogenesis of this disease, preclinical studies of the specific activity and harmlessness of candidate vaccines, as well as options for these developments based on the platforms such as inactivated LASV and its DNA, the reassortant of Mopeia arenavirus, and measles virus attenuated strains, recombinant and replication-defective viruses (smallpox vaccine, Venezuelan equine encephalitis, bovine vesicular stomatitis, adenovirus of chimpanzee) and virus-like particles

Optical properties of photonic crystal slabs with asymmetrical unit cell

Using the unitarity and reciprocity properties of the scattering matrix, we analyse the symmetry and resonant optical properties of the photonic crystal slabs (PCS) with complicated unit cell. We show that the reflectivity is not changed upon the 180deg-rotation of the sample around the normal axis, even in PCS with asymmetrical unit cell. Whereas the transmissivity becomes asymmetrical if the diffraction or absorption are present. The PCS reflectivity peaks to unity near the quasiguided mode resonance for normal light incidence in the absence of diffraction, depolarisation, and absorptive losses. For the oblique incidence the full reflectivity is reached only in symmetrical PCS.Comment: 5 pages, 2 Postscript figure

STUDY OF PATHOGENETIC FEATURES INFECTIOUS CAUSED BY HIGHLY PATHOGENIC INFLUENZA VIRUS A/H5N1 IN WILD DUCKS AND DOMESTIC CHICKEN

Changes in lung, liver and brain were investigated, in wild, ducks and. domestic chicken under experimental infection caused by highly pathogenic avian Influenza virus A/H5N1. Isolation of virus was demonstrated, in swabs from the throat and. cloaca, virus titers were presented, in patterns of organs. Changes in organs of wild, ducks have dystrophic characteristics, but in domestic chickens are of the dystrophic and necrotic nature

Problematic questions in the development of specific prevention of dengue fever

Dengue fever known from literary sources since the Qin dynasty (265-420) is caused in humans when bitten by Aedes mosquitoes infected with the dengue virus (DENV) and manifests as a flu-like disease. A feverish state can be accompanied by dyspeptic disorders (nausea, vomiting, diarrhea) and a rash. Approximately 1-2% of infections are clinically presented as the most severe form – it is dengue hemorrhagic fever/dengue shock syndrome (DHF/DSS) leading to 500 thousand annual hospitalizations with a mortality rate of about 5% in endemic areas.Four genetically removed DENV serotypes (1, 2, 3, and 4) are classified as different types of viruses within the same antigen complex and have almost identical epidemiological features. In 2013 a new serotype DENV-5 was isolated.Until the 1980s in most geographical regions of the world where dengue fever was registered only one or two viral serotypes were detected as an etiological agent of the disease. Over time there is an increase in the cocirculation of four types of viruses which can serve as a key indicator of their global spread. As the “traces” of the four DENV species overlap more and more the threat of severe disease increases due to the phenomenon of antibody-dependent of infection when re-infected with a heterologous viral serotype.Development of specific dengue fever prevention has been underway since 1944 (since the discovery of viral agents of this disease) but the first and so far only licensed in 2015 tetravalent vaccine-Dengvaxia developed by the French pharmaceutical company Sanofi Pasteur has been effective in varying degrees of protection against infection with each of the viral serotypes and in addition dangerous for previously seronegative people. Research aimed at obtaining a safe and effective vaccine is continuing. Neutralizing monoclonal antibodies are a necessary tool for studying the antigenic structure of viral immunogens as base of prevention preparates against dengue fever

L-Glutamine peptides as a means of accelerated rehydration under intense physical activity in athletes

This review is devoted to the theory and practice of the use of glutamine dipeptides in sports. The pathway of L-Glutamine dipeptides is described from the moment of oral intake and entering the intestine to inclusion in intracellular metabolic processes of organs and tissues. The physico-chemical properties of L-Glutamine dipeptides are considered. Urgent effects of L-Glutamine dipeptides under conditions of physical stress and hydration stress, influence on motor and cognitive functions of athletes, positive influence on physical readiness of athletes for prolonged debilitating exercises, reduction of weight loss (rehydration) are described. Positive results of the study of the effect of oral administration of AH and electrolytes on the concentration of plasma electrolytes, physiological indices and neuromuscular fatigue in the process of endurance training, as well as neuroprotective and analgesic properties of L-Glutamine dipeptides are presented

GUT MICROBIOTA AND HYGIENE THEORY OF ATOPY

The indigenous gut microbiota plays a key role in maintaining homeostasis in gastrointestinal tract. The review is devoted to factors influencing gut microbiota composition, involvement of microbiota in formation of systemic and mucosal immunity, the role of disturbances of microbial community in development of allergic disease