Peculiarities of night EEG-monitoring of sleep in children with type 1 diabetes mellitus depending on the glycemia level

BACKGROUND: The patterns of bioelectric activity of the brain in patients with type 1 diabetes mellitus are being actively studied. A recent study of changes in brain bioelectric activity during sleep in children with diabetes mellitus was done without monitoring changes in the level of glycaemia in real time. The current study was conducted with concurrent monitoring of EEG in sleep and glycaemia. AIM: To study the results of night time EEG monitoring of sleep in children with type 1 diabetes mellitus depending on the level of glycaemia. METHODS: This study included 20 children (1017 years of age) with type 1 diabetes. All patients received continuous monitoring of glycaemia and night time EEG of sleep for 9 h. RESULTS: Absence of pathological changes was more often observed in patients with optimal glycaemic indices (n = 9) compared with patients with hypoglycaemic periods (n = 0) (P = 0.011, Fisher exact test) and hyperglycaemia (n = 3) (P = 0.0011, Fisher exact test). Light paroxysmal disturbances (high-amplitude bilateral flares during theta waves in stages 12 of sleep) were more often recorded in patients during periods of hypoglycaemia (n = 3) compared with periods of optimal glycaemia (n = 1) (P = 0.032, Fisher exact test). The hypersynchronous rhythm was also more often detected in patients during periods of hypoglycaemia (n = 3) compared with optimal glycaemia (n = 1) (P = 0.032, Fisher exact test). ECG potentials were more often recorded in hypoglycaemia (n = 4) compared with optimal glycaemia (n = 2) (P = 0.011, Fisher exact test) and hyperglycaemia (n = 3) (P = 0.005, Fisher exact test). The interrelation of brain bioelectric activity and glycaemic indices was seen in patients with hypoglycaemia (positive correlation) and at optimal glycaemia (negative correlation). The highest correlation was seen between ECG potentials (r = +0.61, P 0.05), hypersynchronous rhythm (r = +0.40; P 0.05) and hypoglycaemia. Significant differences between the groups were obtained in the beta range (increase in amplitude and beta-rhythm index) by the spectral analysis. CONCLUSIONS: Disturbance of the bioelectric activity of the brain is seen mainly in the hypoglycaemic state in patients with type 1 diabetes mellitus. This indicates the dysfunction of vegetative regulatory adaptation mechanisms, which can significantly increase the risk of severe hypoglycaemia

Component tree analysis of cystovirus φ6 nucleocapsid Cryo-EM single particle reconstructions

The 3-dimensional structure of the nucleocapsid (NC) of bacteriophage φ6 is described utilizing component tree analysis, a topological and geometric image descriptor. The component trees are derived from density maps of cryo-electron microscopy single particle reconstructions. Analysis determines position and occupancy of structure elements responsible for RNA packaging and transcription. Occupancy of the hexameric nucleotide triphosphorylase (P4) and RNA polymerase (P2) are found to be essentially complete in the NC. The P8 protein lattice likely fixes P4 and P2 in place during maturation. We propose that the viral procapsid (PC) is a dynamic structural intermediate where the P4 and P2 can attach and detach until held in place in mature NCs. During packaging, the PC expands to accommodate the RNA, and P2 translates from its original site near the inner 3-fold axis (20 sites) to the inner 5-fold axis (12 sites) with excess P2 positioned inside the central region of the NC

Protein P7 of the Cystovirus φ6 Is Located at the Three-Fold Axis of the Unexpanded Procapsid

The objective of this study was to determine the location of protein P7, the RNA packaging factor, in the procapsid of the φ6 cystovirus. A comparison of cryo-electron microscopy high-resolution single particle reconstructions of the φ6 complete unexpanded procapsid, the protein P2-minus procapsid (P2 is the RNA directed RNA-polymerase), and the P7-minus procapsid, show that prior to RNA packaging the P7 protein is located near the three-fold axis of symmetry. Difference maps highlight the precise position of P7 and demonstrate that in P7-minus particles the P2 proteins are less localized with reduced densities at the three-fold axes. We propose that P7 performs the mechanical function of stabilizing P2 on the inner protein P1 shell which ensures that entering viral single-stranded RNA is replicated

Morphology of Influenza B/Lee/40 Determined by Cryo-Electron Microscopy

Cryo-electron microscopy projection image analysis and tomography is used to describe the overall architecture of influenza B/Lee/40. Algebraic reconstruction techniques with utilization of volume elements (blobs) are employed to reconstruct tomograms of this pleomorphic virus and distinguish viral surface spikes. The purpose of this research is to examine the architecture of influenza type B virions by cryo-electron tomography and projection image analysis. The aims are to explore the degree of ribonucleoprotein disorder in irregular shaped virions; and to quantify the number and distribution of glycoprotein surface spikes (hemagglutinin and neuraminidase) on influenza B. Projection image analysis of virion morphology shows that the majority (∼83%) of virions are spherical with an average diameter of 134±19 nm. The aspherical virions are larger (average diameter = 155±47 nm), exhibit disruption of the ribonucleoproteins, and show a partial loss of surface protein spikes. A count of glycoprotein spikes indicates that a typical 130 nm diameter type B virion contains ∼460 surface spikes. Configuration of the ribonucleoproteins and surface glycoprotein spikes are visualized in tomogram reconstructions and EM densities visualize extensions of the spikes into the matrix. The importance of the viral matrix in organization of virus structure through interaction with the ribonucleoproteins and the anchoring of the glycoprotein spikes to the matrix is demonstrated

Zika virus-like particle (VLP) based vaccine

The newly emerged mosquito-borne Zika virus poses a major public challenge due to its ability to cause significant birth defects and neurological disorders. The impact of sexual transmission is unclear but raises further concerns about virus dissemination. No specific treatment or vaccine is currently available, thus the development of a safe and effective vaccine is paramount. Here we describe a novel strategy to assemble Zika virus-like particles (VLPs) by co-expressing the structural (CprME) and non-structural (NS2B/NS3) proteins, and demonstrate their effectiveness as vaccines. VLPs are produced in a suspension culture of mammalian cells and self-assembled into particles closely resembling Zika viruses as shown by electron microscopy studies. We tested various VLP vaccines and compared them to analogous compositions of an inactivated Zika virus (In-ZIKV) used as a reference. VLP immunizations elicited high titers of antibodies, as did the In-ZIKV controls. However, in mice the VLP vaccine stimulated significantly higher virus neutralizing antibody titers than comparable formulations of the In-ZIKV vaccine. The serum neutralizing activity elicited by the VLP vaccine was enhanced using a higher VLP dose and with the addition of an adjuvant, reaching neutralizing titers greater than those detected in the serum of a patient who recovered from a Zika infection in Brazil in 2015. Discrepancies in neutralization levels between the VLP vaccine and the In-ZIKV suggest that chemical inactivation has deleterious effects on neutralizing epitopes within the E protein. This along with the inability of a VLP vaccine to cause infection makes it a preferable candidate for vaccine development

Disassembly of the cystovirus ϕ6 envelope by montmorillonite clay

Prior studies of clay–virus interactions have focused on the stability and infectivity of nonenveloped viruses, yielding contradictory results. We hypothesize that the surface charge distribution of the clay and virus envelope dictates how the components react and affect aggregation, viral stability, and infectivity. The bacteriophage Cystoviridae species φ6 used in this study is a good model for enveloped pathogens. The interaction between φ6 and montmorillonite (MMT) clay (the primary component of bentonite) is explored by transmission electron microscopy. The analyses show that MMT–φ6 mixtures undergo heteroaggregation, forming structures in which virtually all the virions are either sequestered between MMT platelet layers or attached to platelet edges. The virions swell and undergo disassembly resulting in partial or total envelope loss. Edge-attached viral envelopes distort to increase contact area with the positively charged platelet edges indicating that the virion surface is negatively charged. The nucleocapsid (NCs) remaining after envelope removal also exhibit distortion, in contrast to detergent-produced NCs which exhibit no distortion. This visually discernible disassembly is a mechanism for loss of infectivity previously unreported by studies of nonenveloped viruses. The MMT-mediated sequestration and disassembly result in reduced infectivity, suggesting that clays may reduce infectivity of enveloped pathogenic viruses in soils and sediments

The ϕ6 Cystovirus Protein P7 Becomes Accessible to Antibodies in the Transcribing Nucleocapsid: A Probe for Viral Structural Elements

Protein P7 is a component of the cystovirus viral polymerase complex. In the unpackaged procapsid, the protein is situated in close proximity to the viral directed RNA polymerase, P2. Cryo-electron microscopy difference maps from the species ϕ6 procapsid have demonstrated that P7 and P2 likely interact prior to viral RNA packaging. The location of P7 in the post-packaged nucleocapsid (NC) remains unknown. P7 may translocate closer to the five-fold axis of a filled procapsid but this has not been directly visualized. We propose that monoclonal antibodies (Mabs) can be selected that serve as probe- reagents for viral assembly and structure. A set of Mabs have been isolated that recognize and bind to the ϕ6 P7. The antibody set contains five unique Mabs, four of which recognize a linear epitope and one which recognizes a conformational epitope. The four unique Mabs that recognize a linear epitope display restricted utilization of Vκ and VH genes. The restricted genetic range among 4 of the 5 antibodies implies that the antibody repertoire is limited. The limitation could be the consequence of a paucity of exposed antigenic sites on the ϕ6 P7 surface. It is further demonstrated that within ϕ6 nucleocapsids that are primed for early-phase transcription, P7 is partially accessible to the Mabs, indicating that the nucleocapsid shell (protein P8) has undergone partial disassembly exposing the protein’s antigenic sites

Cardiac Autonomic Neuropathy and Hypoglycemia as Independent Predictors of QTc Elongation at Night in Adolescents With Type 1 Diabetes: Cohort Study

Background. QTc elongation is the risk factor of sudden cardiac death. Patients with type 1 diabetes (T1D) can have QTc elongation due to hypoglycemia and cardiac autonomic neuropathy (CAN). The separate role of this two factors in QTc elongation development in T1D patients is still unknown.Objective. The aim was to study the role of cardiac autonomic neuropathy and hypoglycemia as independent risk factors of QTc elongation at night in adolescents with T1D.Methods. Patients at the age of 10-17 years old with T1D were enrolled in the cohort study. All patients have undergone simultaneous 24-hour monitoring of electrocardiogram and glycemia. Results of nocturnal monitoring (23:00-07:00) were estimated. QTc elongation > 450 ms was regarded pathological. CAN was diagnosed at decrease of ≥ 2 time domain parameters (SDNN < 101 ms, SDNNi < 48 ms, SDANN < 85 ms, rMSSD < 25 ms). Hypoglycemia was classified as 1st (≥ 3.0 and ≤ 3.9 mmol/L), 2nd (≥ 2.2 and < 3.0 mmol/L) or 3rd (≤ 3.9 mmol/L along with cognitive defects and the need of acute hypoglycemia treatment) level. We also have distinguished prolonged (< 3.0 mmol/L and ≥ 120 min) and asymptomatic (≤3.9 mmol/L and no adrenergic symptoms) nocturnal hypoglycemia. We didn’t analyse hypoglycemia periods with > 9.0 mmol/L.Results. QTc elongation > 450 ms was revealed in 28 out of 100 patients. All patients with QTc > 450 ms were similar on gender, age, HbA1C level with patients without any QTc elongation but they have longer history of T1D and higher frequency of 2nd level hypoglycemia and asymptomatic nocturnal hypoglycemia. According to the data from multivariate regression analysis independent predictors of QTc elongation were the following: CAN — odds ratio (OR) 9.0 (95% confidential interval [CI] 3.3-24.2), 2nd level hypoglycemia — OR 4.4 (95% CI 1.4-14.2), asymptomatic nocturnal hypoglycemia — OR 2.9 (95% CI 1.1-7.7) and T1D duration — OR 1.3 (95% CI 1.0-1.5).Conclusion. CAN and hypoglycemia (both clinically significant and asymptomatic nocturnal) are independent predictors of QTc elongation in adolescents with T1D

Bacteria-clay interaction : Structural changes in smectite induced during biofilm formation

Bacteria play an important role in determining the properties and behavior of clay minerals in natural environments and such interactions have great potential for creating stable biofilms and carbon storage sites in soils, but our knowledge of these interactions are far from complete. The purpose of this study was to understand better the effects of bacteria-generated biofilms on clay interlayer expansion. Mixtures of a colloidal, 2-water hectorite clay and Pseudomonas syringae in a minimal media suspension evolve into a polysaccharide-rich biofilm aggregate in time-series experiments lasting up to 1 week. X-ray diffraction analysis reveals that upon aggregation, the clay undergoes an initial interlayer contraction. Short-duration experiments, up to 72 h, result in a decrease in the d value from 1.50 to 1.26 nm. The initial interlayer contraction is followed in long-duration (up to 1 week) experiments by an expansion of the d value of 1.84 nm. The expansion is probably a result of large, biofilm-produced, polymeric molecules being emplaced in the interlayer site. The resultant organo-clay could provide a possible storage medium for carbon in a microbial colony setting