People with persistent postural-perceptual dizziness demonstrate altered postural strategies in complex visual and cognitive environments

BACKGROUND: People with PPPD report imbalance, increase in symptoms and impaired function within complex visual environments, but understanding of the mechanism for these behaviors is still lacking. OBJECTIVE: To investigate postural control in PPPD we compared changes in center of pressure (COP) and head kinematics of people with PPPD (N = 22) and healthy controls (N = 20) in response to different combinations of visual and cognitive perturbations during a challenging balance task. METHODS: Participants stood in a tandem position. Static or moving stars (0.2 Hz, 5 mm or 32 mm amplitude, anterior-posterior direction) were displayed through a head-mounted display (HTC Vive). On half the trials, participants performed a serial-3 subtraction task. We measured medio-lateral and anterior-posterior path and acceleration of COP and head. RESULTS: Controls significantly increased all COP and head parameters with the cognitive task whereas PPPD increased only COP ML path and acceleration. Only controls significantly increased head anterior-posterior & medio-lateral acceleration with moving visual load. Cognitive task performance was similar between groups. CONCLUSIONS: We observed altered postural strategies in people with PPPD, in the form of reduced movement with challenge, particularly around the head segment. The potential of this simple and portable head-mounted display setup for differential diagnosis of vestibular disorders should be further explored.

Forecasting Approach for Water Pollution Based on Markov Forecast Model

The time scale-arrangement gauging of water contamination is significant and troublesome issue of water contamination organize framework. The time-arrangement information of water contamination is tremendous, high-dimension and non-linear, data removal of it is troublesome. To understand the information digging and gauging for arrangement information of water contamination effectively, an enhanced expectation replica dependent on the smallest amount squares bolster vector engine is introduced in this magazine. To lessen the element of tests, the bit head segment investigation technique is utilized to remove the element data, which contains the vital parts of tests. At that point applying the unascertained thorough assessment technique and Markov estimate to the water value assessment, it defeats not just the vulnerability and arbitrariness in the water quality framework, yet in addition the irregularity of weight assurance, since it utilizes the credit progressive strategy to decide weight of each contamination factor impartially. At that point, through the checking information computation shows the gauge model is exact, yet in addition the outcome is logical and sensible, in view of the use of un-ascertained science strategy. The request model shows that this representation acquires acceptable outcomes, and gives a method of water superiorityestimate. At last, the proposed expectation model is applied in water contamination time-arrangement information determining tests. The exploratory outcomes show that the proposed approach has some preferred exhibitions over the overall techniques, for example, the great prescient precision and solidness in the time-arrangement estimating of water contamination.

The Role of the Technological Residual Stress in Spiral Bevel Gears’ Degradation

The subjects of the examination were automotive components, spiral bevel gears, built up by two main parts, the axle, where the component is prone to fracture, and the head segment, where the working surface can be found. The occasional fracture occurs during the straightening process after the hardening heat treatment. Our aims were to monitor the evolution of the residual stress during the manufacturing processes and to reveal the role of the residual stress in the component’s fracture. The residual stress measurements were carried out via non-destructive X-ray diffraction. To reveal the component’s fracture hardness tests and microstructure measurements were also performed. Based on the results, the fracture of the components were connected to the stress asymmetry which was derived from the microstructure of the early stages of manufacturing.

Pannexin channels increase propidium iodide permeability in frozen–thawed dog spermatozoa

Pannexins (Panx) are proteins that form functional single membrane channels, but they have not yet been described in dogs. The aim of the present study was to detect Panx1, Panx2 and Panx3 in frozen–thawed dog spermatozoa using flow cytometry and immunofluorescence analyses, evaluating the relationship of these proteins with propidium iodide (PI) in frozen–thawed spermatozoa. Fresh and frozen–thawed dog spermatozoa from eight dogs were preincubated with 3 μM PI with or without 15 μM carbenoxolone (CBX) or 1 mM probenecid (PBD), two Panx channel inhibitors, and then incubated with rabbit anti-Panx1, anti-Panx2 and anti-Panx3 antibodies (1 : 200). Panx immunolocalisation was assessed by fluorescence microscopy. Flow cytometry data were evaluated by analysis of variance. All three Panx proteins were found in dog spermatozoa: Panx1 was mostly localised to the acrosomal and equatorial segment, Panx2 was found in the posterior region of the head and tail and Panx3 was localised to the equatorial and posterior head segment. The percentage of PI-positive cells determined by flow cytometry was reduced (P < 0.05) in the presence of Panx inhibitors. These results show that Panx proteins are present in dog spermatozoa and increase PI permeability in frozen–thawed dog sperm, suggesting that the percentage of PI-positive spermatozoa used as an indicator of non-viable cells may lead to overestimation of non-viable cells.

A Structurally Unresolved Head Segment of Defined Length Favors Proper Measles Virus Hemagglutinin Tetramerization and Efficient Membrane Fusion Triggering

ABSTRACTParamyxoviruses include several insidious and ubiquitous pathogens of humans and animals, with measles virus (MeV) being a prominent one. The MeV membrane fusion apparatus consists of a receptor binding protein (hemagglutinin [H]) tetramer and a fusion (F) protein trimer. Four globular MeV H heads are connected to a tetrameric stalk through flexible linkers. We sought here to characterize the function of a 17-residue H-head segment proximal to the stalk that was unresolved in all five MeV H-head crystal or cocrystal structures. In particular, we assessed whether its primary sequence and length are critical for proper protein oligomerization and intracellular transport or for membrane fusion triggering. Extensive alanine substitutions had no effect on fusion triggering, suggesting that sequence identity is not critical for this function. Excessive shortening of this segment reduced or completely abrogated fusion trigger function, while length compensation restored it. We then characterized the mechanism of function loss. Mutated H proteins were efficiently transported to the cell surface, but certain alterations enhancing linker flexibility resulted in accumulation of high-molecular-weight H oligomers. Some oligomers had reduced fusion trigger capacity, while others retained this function. Thus, length and rigidity of the unresolved head segment favor proper H tetramerization and counteract interactions between subunits from different tetramers. The structurally unresolved H-head segment, together with the top of the stalk, may act as a leash to provide the right degree of freedom for the heads of individual tetramers to adopt a triggering-permissive conformation while avoiding improper contacts with heads of neighboring tetramers.IMPORTANCEUnderstanding the molecular mechanism of membrane fusion triggering may allow development of new antiviral strategies. The fusion apparatus of paramyxoviruses consists of a receptor binding tetramer and a fusion protein trimer. Structural analyses of the receptor binding hemagglutinin-neuraminidases of certain paramyxoviruses suggest that fusion triggering is preceded by relocation of its head domains, facilitated by flexible linkers. Having noted a structurally unresolved 17-residue segment linking the globular heads to the tetrameric stalk of the measles virus hemagglutinin (H), we asked whether and how it may facilitate membrane fusion triggering. We conclude that, together with the top of the stalk, the flexible linker keeps H heads on a leash long enough to adopt a triggering-permissive conformation but short enough to limit roaming and improper contacts with heads of neighboring tetramers. All morbillivirus H-protein heads appear to be connected to their stalks through a “leash,” suggesting a conserved triggering mechanism.

Activity of selected hydrolytic enzymes from leeches (Clitellata: Hirudinida) with different feeding strategies

Hydrolase activities of extracts from different parts of the bodies of parasitic (Theromyzon tessulatum, Piscicola geometra) and predatory (Erpobdella octoculata, Glossiphonia complanata) leeches were examined. The highest activity was detected in the extracts from sections containing the intestine. Hydrolase activities in the crop and intestine of parasitic leeches were higher than in predatory leeches. The high activity of most of hydrolases in those segments may indicate the intensity of digestion and absorption processes in leeches. A lack of trypsin activity and low chymotrypsin activity are likely to result from the presence of inhibitors of these enzymes. The high activity of the majority of the analyzed hydrolases in extracts derived from the head segment of predatory leeches enables, through digestion of tissues, their easy access to physiological fluids of a host. In turn, in extracts from the head segment of predatory leeches, only four hydrolases were shown to be active. Lipase activity was not found in any of the samples, while α-galactosidase activity was found only in extracts from the head segment of T. tessulatum and P. geometra. Trypsin activity was detected in the extract from the intestine contents of H. sanguisuga and in the extract from the head segment of P. geometra. The results demonstrate the presence of majority of hydrolases occurring in other animals in the alimentary tract of leeches. The study also shows that the crop of leeches is not only a food reservoir, but also the site where digestion and absorption processes take place.

Musculoskeletal patterning in the pharyngeal segments of the zebrafish embryo

The head skeleton and muscles of the zebrafish develop in a stereotyped pattern in the embryo, including seven pharyngeal arches and a basicranium underlying the brain and sense organs. To investigate how individual cartilages and muscles are specified and organized within each head segment, we have examined their early differentiation using Alcian labeling of cartilage and expression of several molecular markers of muscle cells. Zebrafish larvae begin feeding by four days after fertilization, but cartilage and muscle precursors develop in the pharyngeal arches up to 2 days earlier. These chondroblasts and myoblasts lie close together within each segment and differentiate in synchrony, perhaps reflecting the interdependent nature of their patterning. Initially, cells within a segment condense and gradually become subdivided into individual dorsal and ventral structures of the differentiated arch. Cartilages or muscles in one segment show similar patterns of condensation and differentiation as their homologues in another, but vary in size and shape in the most anterior (mandibular and hyoid) and posterior (tooth-bearing) arches, possibly as a consequence of changes in the timing of their development. Our results reveal a segmental scaffold of early cartilage and muscle precursors and suggest that interactions between them coordinate their patterning in the embryo. These data provide a descriptive basis for genetic analyses of craniofacial patterning.

Homeotic complex and teashirt genes co-operate to establish trunk segmental identities in Drosophila

Homeotic genes determine the identities of metameres in Drosophila. We have examined functional aspects of the homeotic gene teashirt by ectopically expressing its product under the control of a heat-shock promoter during embryogenesis. Our results confirm that the gene is critical for segmental identity of the larva. Under mild heat-shock conditions, the Teashirt protein induces an almost complete transformation of the labial to prothoracic segmental identity, when expressed before 8 hours of development. Positive autoregulation of the endogenous teashirt gene and the presence of Sex combs reduced protein in the labium explain this homeosis. Patterns in the maxillary and a more anterior head segment are partly replaced with trunk ones. Additional Teashirt protein has no effect on the identity of the trunk segments where the gene is normally expressed; teashirt function is overridden by some homeotic complex acting in the posterior trunk. Strong heat-shock regimes provoke novel defects: ectopic sense organs differentiate in posterior abdominal segments and trunk pattern elements differentiate in the ninth abdominal segment. Teashirt acts in a partially redundant way with certain homeotic complex proteins but co-operates with them for the establishment of specific segment types. We suggest that Teashirt and HOM-C proteins regulate common sets of downstream target genes.