Optical aspect of deformation analysis in the bone-denture complex

The aim of this study was to register and measure any deformation of mandible models under load. The method for full field measurement of strain is done by using the ARAMIS three-dimensional image correlation system. The system uses two digital cameras that provide a synchronized stereo view of the specimen and the results show the complete strain field during the tests. The biggest deformation values were just under the working force of the biggest intensity 500 N, and for the region of the lower second premolar the deformation is 625 microm. The following study is presented that highlight the use of stereometric measuring system for modern research. It is shown that this measuring methodology can capture the trends of the experiments.     

Uptake and incorporation of sialic acid by the tick Ixodes ricinus

We describe the detection of sialylated N-linked glycans in partially fed Ixodes ricinus tick females using matrix-assisted laser desorption/ionization time-of-flight/time-of-flight mass spectrometry. Sialylated glycans were detected in salivary glands as well as in tick guts and we propose the host origin of these structures. In addition, we mapped the transport of sialylated structures from the blood meal through the gut to the salivary glands using electron microscopy. Specific localization of sialylated glycans to basement membranes of salivary glands was observed. Finally, the influence of the sample preparation methods for electron microscopy on ultrastructure and immunogold labeling was evaluated.     

Homeostatic synaptic scaling is regulated by protein SUMOylation

Homeostatic scaling allows neurons to alter synaptic transmission to compensate for changes in network activity. Here, we show that suppression of network activity with tetrodotoxin, which increases surface expression of AMPA receptors (AMPARs), dramatically reduces levels of the deSUMOylating (where SUMO is small ubiquitin-like modifier) enzyme SENP1, leading to a consequent increase in protein SUMOylation. Overexpression of the catalytic domain of SENP1 prevents this scaling effect, and we identify Arc as a SUMO substrate involved in the tetrodotoxin-induced increase in AMPAR surface expression. Thus, protein SUMOylation plays an important and previously unsuspected role in synaptic trafficking of AMPARs that underlies homeostatic scaling.     

Biochemical insight into physiological effects of H₂S: reaction with peroxynitrite and formation of a new nitric oxide donor, sulfinyl nitrite

The reaction of hydrogen sulfide (H2S) with peroxynitrite (a key mediator in numerous pathological states) was studied in vitro and in different cellular models. The results show that H2S can scavenge peroxynitrite with a corresponding second order rate constant of 3.3 ± 0.4 × 103 M?1·s?1 at 23°C (8 ± 2 × 103 M?1·s?1 at 37°C). Activation parameters for the reaction (ΔH?, ΔS? and ΔV?) revealed that the mechanism is rather associative than multi-step free-radical as expected for other thiols. This is in agreement with a primary formation of a new reaction product characterized by spectral and computational studies as HSNO? (thionitrate), predominantly present as sulfinyl nitrite, HS(O)NO. This is the first time a thionitrate has been shown to be generated under biologically relevant conditions. The potential of HS(O)NO to serve as a NO donor in a pH-dependent manner and its ability to release NO inside the cells has been demonstrated. Thus sulfide modulates the chemistry and biological effects of peroxynitrite by its scavenging and formation of a new chemical entity (HSNO?) with the potential to release NO, suppressing the pro-apoptotic, oxidative and nitrative properties of peroxynitrite. Physiological concentrations of H?S abrogated peroxynitrite-induced cell damage as demonstrated by the: (i) inhibition of apoptosis and necrosis caused by peroxynitrite; (ii) prevention of protein nitration; and (iii) inhibition of PARP-1 [poly(ADP-ribose) polymerase 1] activation in cellular models, implying that a major part of the cytoprotective effects of hydrogen sulfide may be mediated by modulation of peroxynitrite chemistry, in particular under inflammatory conditions.     

Preparation of diamino pseudodisaccharide derivatives from 1,6-anhydro-beta-D-hexopyranoses via aziridine-ring cleavage

Twelve positional isomers of diamino pseudodisaccharide derivatives with gluco-gluco configuration have been prepared using aziridine-ring cleavage of epimino derivatives of 1,6-anhydro-beta-D-hexopyranoses of the D-allo, D-manno, and D-galacto configuration by 2-, 3-, and 4-amino derivatives of 1,6-anhydro-beta-D-glucopyranose. The N-substitution of the aziridine ring by a 2-nitrobenzenesulfonyl group and ionic-liquid solvent (N-methylpyridinium tosylate) was used to obtain cleavage products in high yield (64-93%). The cleavage reactions proceeded according to the Fürst-Plattner rule and only trans-diaxial stereoisomers were formed.     

Dynamics of mutated GFAP aggregates revealed by real-time imaging of an astrocyte model of Alexander disease

Alexander disease (AxD) is a rare neurodegenerative disorder characterized by large cytoplasmic aggregates in astrocytes and myelin abnormalities and caused by dominant mutations in the gene encoding glial fibrillary acidic protein (GFAP), the main intermediate filament protein in astrocytes. We tested the effects of three mutations (R236H, R76H and L232P) associated with AxD in cells transiently expressing mutated GFAP fused to green fluorescent protein (GFP). Mutated GFAP-GFP expressed in astrocytes formed networks or aggregates similar to those found in the brains of patients with the disease. Time-lapse recordings of living astrocytes showed that aggregates of mutated GFAP-GFP may either disappear, associated with cell survival, or coalesce in a huge juxtanuclear structure associated with cell death. Immunolabeling of fixed cells suggested that this gathering of aggregates forms an aggresome-like structure. Proteasome inhibition and immunoprecipitation assays revealed mutated GFAP-GFP ubiquitination, suggesting a role of the ubiquitin-proteasome system in the disaggregation process. In astrocytes from wild-type-, GFAP-, and vimentin-deficient mice, mutated GFAP-GFP aggregated or formed a network, depending on qualitative and quantitative interactions with normal intermediate filament partners. Particularly, vimentin displayed an anti-aggregation effect on mutated GFAP. Our data indicate a dynamic and reversible aggregation of mutated GFAP, suggesting that therapeutic approaches may be possible.     

The influence of deep hypothermia on inflammatory status,tissue hypoxia and endocrine function of adipose tissue during cardiac surgery

Changes in endocrine function of adipose tissue during surgery, such as excessive production of proinflammatory cytokines, can significantly alter metabolic response to surgery and worsen its outcomes and prognosis of patients. Therapeutic hypothermia has been used to prevent damage connected with perioperative ischemia and hypoperfusion. The aim of our study was to explore the influence of deep hypothermia on systemic and local inflammation, adipose tissue hypoxia and adipocytokine production. We compared serum concentrations of proinflammatory markers (CRP, IL-6, IL-8, sIL-2R, sTNFRI, PCT) and mRNA expression of selected genes involved in inflammatory reactions (IL-6, TNF-α, MCP-1, MIF) and adaptation to hypoxia and oxidative stress (HIF1-α, MT3, GLUT1, IRS1, GPX1, BCL-2) in subcutaneous and visceral adipose tissue and in isolated adipocytes of patients undergoing cardiosurgical operation with hypothermic period. Deep hypothermia significantly delayed the onset of surgery-related systemic inflammatory response. The relative gene expression of the studied genes was not altered during the hypothermic period, but was significantly changed in six out of ten studied genes (IL-6, MCP-1, TNF-α, HIF1-α, GLUT1, GPX1) at the end of surgery. Our results show that deep hypothermia suppresses the development of systemic inflammatory response, delays the onset of local adipose tissue inflammation and thus may protect against excessive expression of proinflammatory and hypoxia-related factors in patients undergoing elective cardiac surgery procedure.