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Abstract: Dissolved oxygen has known paramagnetic effects in magnetic resonance imaging (MRI). The aim ofthis study was to compare the effects of normobaric oxygenation (NBO) and hyperbaric oxygenation (HBO) on hu-man brain MRI signal intensities.Patients and methods. Baseline brain MRI was performed in 17 healthy subjects (mean age 27.8 ± 3.2). MRI wasrepeated after exposure to the NBO and HBO at different time points (0 min, 25 min, 50 min). Signal intensities in T1-weighted, T2-weighted images and fluid attenuated inversion recovery (FLAIR) signal intensities of several intracranialstructures were compared between NBO and HBO.Results. Increased T1-weighted signal intensities were observed in white and deep grey brain matter, cerebrospinalfluid (CSF), venous blood and vitreous body after exposure to NBO as well as to HBO compared to baseline (Dunnett’stest, p < 0.05) without significant differences between both protocols. There was also no significant difference in T2-weighted signal intensities between NBO and HBO. FLAIR signal intensities were increased only in the vitreous bodyafter NBO and HBO and FLAIR signal of caudate nucleus was decreased after NBO (Dunnett’s test, p < 0.05). Thestatistically significant differences in FLAIR signal intensities were found between NBO and HBO (paired t-test, p < 0.05)in most observed brain structures (paired t-test, p < 0.05).Conclusions. Our results show that NBO and HBO alters signal intensities T1-weighted and FLAIR images of humanbrain. The differences between NBO and HBO are most pronounced in FLAIR imaging.
Keywords: hyperbaric oxygen, normobaric oxygen, magnetic resonance, human brain
Published in DiRROS: 25.07.2024; Views: 105; Downloads: 59
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Keywords: prostate translocation, prostate distortion, gland deformation, bladder volume, magnetic resonance imaging, radiation therapy planning
Published in DiRROS: 12.07.2024; Views: 103; Downloads: 55
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Abstract: Understanding the neural underpinning of human gait and balance is one of the most pertinent challenges for 21st-century translational neuroscience due to the profound impact that falls and mobility disturbances have on our aging population. Posture and gait control does not happen automatically, as previously believed, but rather requires continuous involvement of central nervous mechanisms. To effectively exert control over the body, the brain must integrate multiple streams of sensory information, including visual, vestibular, and somatosensory signals. The mechanisms which underpin the integration of these multisensory signals are the principal topic of the present work. Existing multisensory integration theories focus on how failure of cognitive processes thought to be involved in multisensory integration leads to falls in older adults. Insufficient emphasis, however, has been placed on specific contributions of individual sensory modalities to multisensory integration processes and cross-modal interactions that occur between the sensory modalities in relation to gait and balance. In the present work, we review the contributions of somatosensory, visual, and vestibular modalities, along with their multisensory intersections to gait and balance in older adults and patients with Parkinson's disease. We also review evidence of vestibular contributions to multisensory temporal binding windows, previously shown to be highly pertinent to fall risk in older adults. Lastly, we relate multisensory vestibular mechanisms to potential neural substrates, both at the level of neurobiology (concerning positron emission tomography imaging) and at the level of electrophysiology (concerning electroencephalography). We hope that this integrative review, drawing influence across multiple subdisciplines of neuroscience, paves the way for novel research directions and therapeutic neuromodulatory approaches, to improve the lives of older adults and patients with neurodegenerative diseases.
Keywords: aging, gait, balance, encephalography, functional magnetic resonance imaging, multisensory integration
Published in DiRROS: 17.06.2024; Views: 177; Downloads: 205
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Abstract: The aim of this paper is to study some variations of the Zhang-Zhang polynomial for phenylenes, which can be obtained as special cases of the multivariable Zhang-Zhang polynomial. Firstly, we prove the equality between the first Zhang-Zhang polynomial of a phenylene and the generalized Zhang-Zhang polynomial of some benzenoid graph, which enables us to prove also the equality between the first Zhang-Zhang polynomial and the generalized cube polynomial of the resonance graph. Next, some results on the roots of the second Zhang-Zhang polynomial of phenylenes are provided and another expression for this polynomial is established. Finally, we give structural interpretation for (partial) derivatives of different Zhang-Zhang polynomials.
Keywords: graph theory, resonance graphs, polynomials
Published in DiRROS: 18.03.2024; Views: 265; Downloads: 97
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Abstract: Plasmonic Au (1 wt%) catalysts deposited on hydrothermally synthesized TiO2 nanorods (TNR) were investigated in this study. Based on the duration of mixing of the Au precursor/TNR suspension during the wet impregnation synthesis and parameters of the end calcination, Au/TiO2 catalysts with different sizes of Au nanoparticles (Au NPs) were obtained. The prepared solids were thoroughly characterized by several instrumental techniques to investigate property-activity relationships. Regardless of the size of Au particles on the catalyst surface, an absorption peak at 550 nm occurred in all UV-Vis diffuse reflectance spectra of the investigated Au/TiO2 catalysts, which is characteristic of the localized surface plasmon resonance effect exerted by metallic Au NPs. By measuring the formation of reactive oxygen species under visible-light illumination using various scavengers, the production of superoxide anion radicals (O2•single bond) and hydroxyl radicals were identified, however, the former were found to represent the main reactive oxygen species that govern the oxidation of aqueous bisphenol A (BPA) employed as a model organic pollutant. The activity of Au/TiO2 catalysts for the generation of O2•single bond radicals (and BPA oxidation) increases by increasing the Schottky barrier height, which is due to the slow reduction of water-dissolved O2 on the catalyst surface.
Keywords: heterogeneous photocatalysis, titanate nanorods, gold nanoparticles, wet impregnation, localized surface plasmon resonance effect
Published in DiRROS: 26.04.2023; Views: 774; Downloads: 340
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