161 research outputs found
Microgravitational effects on the neurovestibular system and countermeasures to facilitate safe and effective adaptation to changes in gravity during future Mars explorations
1.1 Introduction
With the Artemis program National Aeronautics and Space Administration (NASA) plans to land humans on the moon to prepare for the next giant leap, Mars. In order to achieve this ambitious goal, lots of medical and physiological obstacles have to be overcome to ensure a safe voyage. A common but manageable issue with space travel has been neurovestibular dysfunction and altered sensorimotor functions, resulting in symptoms of space motion sickness (SMS) and spatial disorientation. With increasing spaceflight duration and adaptation to various gravities, this hurdle becomes more prominent and will require effective countermeasures.
1.2 Purpose of the study
The purpose of this study is to get a closer look at how microgravity affects the neurovestibular system, and to consider which countermeasures that can assist in a safe and effective adaptations to gravitational changes.
1.3 Material and method
By executing a systematical literature search through the databases PubMed and MEDLINE, articles were found and included in the thesis based on carefully selected criteria. The main search in PubMed resulted in 1780 articles, which first went through a filtration to exclude articles in other languages than English, published before 2011 and with no available abstract or full text. 132 articles’ title and abstract were then reviewed for relevance based on the selection criteria. 94 articles were excluded, and the remaining 36 articles were read in full text. Of these, 19 articles were relevant and contributed to the purpose of the study, and therefore included in the thesis. To cover articles not found in PubMed, another search was carried out in MEDLINE, providing an additional 4 articles.
1.4 Results
Studies has shown that space motion sickness and spatial disorientation mainly affect astronauts during and right after gravitational transitioning. When being exposed to microgravity for longer durations, adaptation mechanisms are activated and leads to utricular deconditioning with synaptic plasticity and decreased ocular counter-roll reflex.
Susceptibility to space motion sickness seems to be higher in females, astronauts with a visual-depended orientation preference and increased otolith mass asymmetry.
Pharmaceuticals, especially scopolamine and promethazine, are widely used to prevent or to ease symptoms of SMS. The effect of these drugs is highly variating. Scopalamine has been found to be quite efficient in lower the symptoms, but has shown side effects of drowsiness, which could be counteracted by combining scopolamine with dextroamphetamine (ScopeDex).
Artificial gravity (AG) is suggested as a possible and effective countermeasure against vestibular deconditioning and intermittent exposures has been proven to be more tolerable. Virtual reality has been tested and showed promising results in modifying orientation preference to be less depended on visual cues. Galvanic vestibular stimulation is an analog creating similar altered vestibular inputs as microgravity and can be used in preflight adaptation training.
1.5 Conclusion
Microgravity can induce space motion sickness and spatial disorientation in astronauts, especially during gravitational transitioning. Long-duration exposure also leads to utricular deconditioning with synaptic plasticity and decreased ocular counter-roll reflex, which contributes to reentry symptoms.
Susceptibility to SMS variates and can be mapped with Motion Sickness Susceptibility Questionnaire, as well as vestibular and visual tests. Females seems to be more susceptible, due to their orientation preference being more visual-dependent. The sensory conflict, which leads to SMS, has been shown to increase in astronauts with marked otolith mass asymmetry.
Countermeasures include the use of pharmaceuticals, with individual and limited effect, and preflight training to aid adaptation through galvanic vestibular stimulations, virtual reality and artificial gravity.
There is a call for future research to develop countermeasures that are both effective and affordable
A Novel Betaproteobacterial Agent of Gill Epitheliocystis in Seawater Farmed Atlantic Salmon (Salmo salar)
Epitheliocystis, a disease characterised by cytoplasmic bacterial inclusions (cysts) in the gill and less commonly skin epithelial cells, has been reported in many marine and freshwater fish species and may be associated with mortality. Previously, molecular and ultrastructural analyses have exclusively associated members of the Chlamydiae with such inclusions. Here we investigated a population of farmed Atlantic salmon from the west coast of Norway displaying gill epitheliocystis. Although ‘Candidatus Piscichlamydia salmonis’, previously reported to be present in such cysts, was detected by PCR in most of the gill samples analysed, this bacterium was found to be a rare member of the gill microbiota, and not associated with the observed cysts as demonstrated by fluorescence in situ hybridization assays. The application of a broad range 16 S rRNA targeted PCR assay instead identified a novel betaproteobacterium as an abundant member of the gill microbiota. Fluorescence in situ hybridization demonstrated that this bacterium, tentatively classified as ‘Candidatus Branchiomonas cysticola’, was the cyst-forming agent in these samples. While histology and ultrastructure of ‘Ca. B. cysticola’ cysts revealed forms similar to the reticulate and intermediate bodies described in earlier reports from salmon in seawater, no elementary bodies typical of the chlamydial developmental cycle were observed. In conclusion, this study identified a novel agent of epitheliocystis in sea-farmed Atlantic salmon and demonstrated that these cysts can be caused by bacteria phylogenetically distinct from the Chlamydiae
International variation in the definition of ‘main condition' in ICD-coded health data
Hospital-based medical records are abstracted to create International Classification of Disease (ICD) coded discharge health data in many countries. The ‘main condition' is not defined in a consistent manner internationally. Some countries employ a ‘reason for admission' rule as the basis for the main condition, while other countries employ a ‘resource use' rule. A few countries have recently transitioned from one of these approaches to the other. The definition of ‘main condition' in such ICD data matters when it is used to define a disease cohort to assign diagnosis-related groups and to perform risk adjustment. We propose a method of harmonizing the international definition to enable researchers and international organizations using ICD-coded health data to aggregate or compare hospital care and outcomes across countries in a consistent manner. Inter-observer reliability of alternative harmonization approaches should be evaluated before finalizing the definition and adopting it worldwid
International variation in the definition of 'main condition' in ICD-coded health data
Hospital-based medical records are abstracted to create International Classification of Disease (ICD) coded discharge health data in many countries. The 'main condition' is not defined in a consistent manner internationally. Some countries employ a 'reason for admission' rule as the basis for the main condition, while other countries employ a 'resource use' rule. A few countries have recently transitioned from one of these approaches to the other. The definition of 'main condition' in such ICD data matters when it is used to define a disease cohort to assign diagnosis-related groups and to perform risk adjustment. We propose a method of harmonizing the international definition to enable researchers and international organizations using ICD-coded health data to aggregate or compare hospital care and outcomes across countries in a consistent manner. Inter-observer reliability of alternative harmonization approaches should be evaluated before finalizing the definition and adopting it worldwide
Dietary b-glucan (MacroGard®) enhances survival of first feeding turbot (Scophthalmus maximus) larvae by altering immunity, metabolism and microbiota
Reflecting the natural biology of mass spawning fish aquaculture production of fish larvae is often hampered by high and unpredictable mortality rates. The present study aimed to enhance larval performance and immunity via the oral administration of an immunomodulator, β-glucan (MacroGard®) in turbot (Scophthalmus maximus). Rotifers (Brachionus plicatilis) were incubated with or without yeast β-1,3/1,6-glucan in form of MacroGard® at a concentration of 0.5 g/L. Rotifers were fed to first feeding turbot larvae once a day. From day 13 dph onwards all tanks were additionally fed untreated Artemia sp. nauplii (1 nauplius ml/L). Daily mortality was monitored and larvae were sampled at 11 and 24 dph for expression of 30 genes, microbiota analysis, trypsin activity and size measurements. Along with the feeding of β-glucan daily mortality was significantly reduced by ca. 15% and an alteration of the larval microbiota was observed. At 11 dph gene expression of trypsin and chymotrypsin was elevated in the MacroGard® fed fish, which resulted in heightened tryptic enzyme activity. No effect on genes encoding antioxidative proteins was observed, whilst the immune response was clearly modulated by β-glucan. At 11 dph complement component c3 was elevated whilst cytokines, antimicrobial peptides, toll like receptor 3 and heat shock protein 70 were not affected. At the later time point (24 dph) an anti-inflammatory effect in form of a down-regulation of hsp 70, tnf-α and il-1β was observed. We conclude that the administration of MacroGard® induced an immunomodulatory response and could be used as an effective measure to increase survival in rearing of turbot
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Masteroppgave i billedkunst - Kunsthøgskolen i Oslo, Avdeling Kunstakademiet, 2012Skriftlig obligatorisk arbeid levert som del av MA avslutningsarbeid ved Kunstakademie
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