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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
71

Development of Ethologically-Based Inhibitory Avoidance Models of Fear Memory

Dalrymple, Savannah 20 June 2017 (has links)
Translational research provides a unique opportunity to investigate innate and conditioned fear to develop an integrated understanding of anxiety disorders, ultimately improving treatment for those afflicted. Many fear conditioning paradigms use physically aversive stimuli to induce fear but ethological stimuli may better represent psychological disorders from a translational standpoint. Natural predators and immobilization have been successful in inducing both innate and contextually conditioned fear in rodents but an inhibitory avoidance paradigm that uses ethologically relevant stimuli has yet to be developed. To expand the use of these stimuli into inhibitory avoidance conditioning, an inhibitory avoidance paradigm was developed to include a range of ethologically relevant psychologically (predator exposure, physical restraint) and physically aversive stimuli (electric shock). Adult male Sprague-Dawley rats were conditioned using a step-through inhibitory avoidance model to associate crossing between two compartments with the presentation of an aversive stimulus. Subjects were assessed for conditioned fear measured by crossing latency, freezing behavior and defecation during conditioning and a contextual memory test. Freezing behavior within the conditioning chamber remained constant throughout conditioning regardless of stimulus but all groups conditioned with an aversive stimulus showed significant increases in crossing latency both overtime and during the retention test compared to subjects that received no aversive stimulus after crossing, indicating that inhibitory avoidance conditioning was achieved. Significant increases in defecation were also observed for footshock and predator exposed animals and this effect was intensified by predator exposure, but only after repeated exposures. With this, both predator based and restraint-based variations of the inhibitory avoidance model (PBIA and RBIA, respectively) have been successfully established and have been shown to induce evidence of emotionality similar to those seen in traditional shock-based inhibitory avoidance (SBIA) models. Successful development of PBIA and RBIA expands the range of stimuli that can be used with conventional inhibitory avoidance models, allowing for investigation into topics that have yet to be addressed in inhibitory avoidance conditioning.
72

Vyhodnocení aktivity potenciálně antifungálních látek pomocí mikrodiluční bujónové metody / Evaluation of activity of potentional antifungal substances through the use of microdilution broth method

Ťapuchová, Ivana January 2017 (has links)
Department of Biological and Medical Sciences Faculty of Pharmacy in Hradec Králové Charles University in Prague Author: Ivana Ťapuchová Title of diploma thesis: Evaluation of activity of potentional antifungal substances through the use of microdilution broth method Supervisor: Mgr. Marcela Vejsová, Ph.D. Background: The aim of this diploma thesis was to evaluate potential antifungal activity of 52 test substances which were develope at the Department of anorganic and organic chemistry Faculty of Pharmacy in Hradec Králové Charles University in Prague. Methods: For testing we used microdilution broth method on eight strains of yeasts and filamentous fungi in the laboratory of Department of Biological and Medical Sciences. Results: Overall 26 test substances with various substituents had antifungal activity. These substances was derivates of 4-aminobenzoic acid, 4-aminosalicylic acid, 5-aminosalicylic acid and large group derivates of sulfonamids. The most sensitive strain was dermatophyt Trichophyton mentagrophytes, the least sensitive strain was filamentous fungi Absidia corymbifera. Conclusions: Despite there was observed antifungal activity in low concentrations of derivates, it is necessary to perform next tests and clinical studies to prove efficiency and safety for use. Key words: yeasts,...
73

Investigation of Inhibitory Influences in Neuronal Monolayer Networks Cultured from Mouse Spinal Cord

Jordan, Russell S. (Russell Stall) 08 1900 (has links)
The effects of the inhibitory neurotransmitters gammaamino butyric acid (GABA) and glycine were characterized on spontaneous activity recorded from mouse spinal cord cultures. The GABA concentration which completely inhibited burst activity was chosen as a quantifiable measure of culture drug response and was used to 1) assess interculture and intraculture variability, 2) determine the influence of culture age and initial activity on GABA responses, and 3) compare the GABA responses between networks obtained from whole spinal cord and ventral half spinal cord. Results showed that 1) no significant variability existed either within or among cultures, 2) the initial culture activity directly affected GABA responses, 3) the culture age had no effect on GABA responses, and 4) there was no significant difference in GABA responses between the two spinal cord tissues.
74

In vivo hodnocení účinnosti nového reaktivátoru vůči tabunu / In vivo evaluation of the efficacy of the novel reactivator against tabun

Kuzmiaková, Natália January 2020 (has links)
Charles University in Prague Faculty of Pharmacy in Hradec Králové Department of Pharmacology and Toxicology Candidate: Natália Kuzmiaková Supervisor: PharmDr. Marie Vopršalová, CSc . Consultant: mjr. PharmDr. Vendula Hepnarová, Ph.D. Title of diploma thesis: In vivo evaluation of the efficacy of the novel reactivator against tabun. This study tackles the problem of irreversible inhibition of acetylcholinesterase (AChE). This enzyme degrades neurotransmitter acetylcholine (ACh), wich ensures transmisson of nerve impulses in central nervous system and in periphery. Organophospates (OP) are substances that cause irreversible blocade of AChE and that susubsequently leads to accumulation of AChE in synapses and inducing of muscarinic and nicotinic effects for life threatening condition. Oximic nature reactivators shown to this day the gratest potencial in inhibiting OP bond with AChE. Because reactivation abilities of to date synthesided oxime are not sufficient, new reactivators are being researched. The doal of my work was to test the potencial to reactivate AChe one of them (precisely oxime K 870). The method i used was colorimetric Ellman method modified by Bajgar, where the activity of AChE after reactivation was measured by absorbance in brain, diaphragm and blood of modeled orgamisms. The...
75

Identifying neurobiological predictors of substance use onset during adolescence

Oot, Emily 29 May 2020 (has links)
BACKGROUND: Early initiation of alcohol and other substance use is considered one of the most important risk factors for the later development of an alcohol use disorder. However, it is not yet well understood to what extent this increased risk reflects neurobiological changes driven by the use itself, and to what extent it reflects pre-existing traits and patterns. This dissertation therefore aims to identify neurobiological and neuropsychological markers that exist prior to the initiation of substance use and may confer risk for earlier use onset. Specifically, the research places a focus on the domains of inhibitory control and learning and memory. METHODS: Adolescents (n=81) were enrolled into the study prior to the initiation of alcohol or other drug use at 13-14 years old to complete baseline brain imaging. Neuroimaging included acquisition of structural magnetic resonance imaging (MRI) and task functional magnetic resonance imaging (fMRI) during response inhibition (emotional Go-NoGo) and spatial memory (virtual Morris Water Task) tasks. Participants also completed a neuropsychological battery that included the California Verbal Learning Test Children’s Version (CVLT-C). Subjects were then followed for up to three years via quarterly online surveys in order to assess initiation of alcohol and substance use. Those who went on to endorse initiating substance use prior to reaching 16 years of age were included in an initiating group (IG, n=21) and those who turned 16 having continuously denied substance use were included in a non-initiating comparison group (CG, n=24). RESULTS: Performance measures on the emotional Go-NoGo (NoGo trial accuracy, Go trial accuracy, Go trial reaction time) showed no significant group differences between IG and CG. Functional brain activation differences, however, were observed in bilateral inferior frontal gyrus (IFG), with CG showing greater activation relative to IG on inhibitory (NoGo) trials with negative versus neutral emotional background images (Negative NoGo>Neutral NoGo). Performance on learning trials for the virtual Morris Water Task, completed offline prior to scanning, showed a subtle learning difference between groups, but no performance or functional brain activation differences were observed on Retrieval or Motor control trials completed during scanning. Performance on the neuropsychological test of verbal learning and memory (CVLT-C) indicated worse learning and memory in IG relative to CG (fewer correct responses on both the Long-Delay Free-Recall and the Recognition trials). CONCLUSIONS: These findings help characterize neurobiological and neuropsychological patterns that exist prior to exposure to substances, and thus may help differentiate adolescents who go on to initiate substance use earlier in adolescence from those who do not. Results suggest brain activation differences in frontal regions may predate use, while activation differences in hippocampal memory systems (observed in some cross-sectional studies of alcohol use) may not. These data help clarify questions of causality and provide a foundation for informing strategies for prevention and intervention efforts in maladaptive alcohol and substance use.
76

Vliv inhibitorů BSO, Lycorine a AIP na biosyntézu sekundárních metabolitů jednobuněčné řasy Scenedesmus quadricauda

Rankić, Ivan January 2018 (has links)
The theoretical overview summarize the characteristics of algae and their primary and secondary metabolism. It also deals with inhibitors of ascorbic acid, glutathione and polyphenolic compounds synthesis. The practical part studies the influence of selected inhibitors (BSO, Lyc, AIP) and CdCl2 on the secondary metabolites production and biomass growth in freshwater microalgae Scenedesmus quadricauda. The content of secondary metabolites (eg. caffeic acid, chlorogenic acid, salicylic acid, cinnamic acid, p-coumaric acid) was detected by HPLC-MS. Furthermore, the total antioxidant capacity, the total polyphenol content and the total flavonoid content was determined spectrophotometrically. All the inhibitors used, reduced S. quadricauda growth in comparison with control samples. The most pronounced inhibitory effect was observed in the samples treated with Lyc + Cd after 7 days of experiment. All the treated samples responded to the stress factors by altering metabolic pathways and inhibiting growth. As a result, there were changes in the composition and the amount of selected secondary metabolites versus the control samples. At the same time, in most cases, the biosynthesis of polyphenolic and flavonoid substances has been stimulated. The oxidative reduction equilibrium and the induction of oxidative stress were probably impaired.
77

Vliv dusíkato-sirného hnojiva s inhibitorem nitrifikace na výnos a kvalitu zrna pšenice ozimé

Vícha, Lukáš January 2019 (has links)
This diploma thesis examines an impact of a nitrogen-sulphur fertilizer with and without a nitrification inhibitor on a yield and quality of a winter wheat grain. From a qualitative feature there has been observed an impact of fertilizers on a volume weight, nitrogen substances, gluten and sedimentation value. The research was conducted in a form of small fields experiment in a business year 2015/2016, 2016/2017 and 2017/2018 in a different localities. The first locality can be found on a South Moravia region specifically at experimental fields of School agricultural enterprise in Žabčice and the second is at Research fodder plants station in Vatín in Vysočina. There has been included five different variants in a research. 1. Unfertilized, 2. CAN + CAN, 3. ANAS + CAN (ammonium nitrate + ammonium sulfate), 4. CAN + ANAS, 5. CAN + ENSIN (ammonium nitrate + ammonium sulfate + inhibitor of nitrification). The results show, that an influence of fertilizer was influenced by a weather conditions in a particular year, when was yield increased in a 2016/2017 by 30 % against a previous year. The yield was also influenced by localities in which has been held. The difference was also between individual variants of fertiliszrs where the variant LAD + ENSIN performed the best with an average yield of 8,18 t/ha. Regarding the qualitative parameters of grain there has been also differences between individual years, localities and also fertiliser variants, however some of the values did not fulfilled norms for a food wheat, so the wheat is in general evaluated as a fodder wheat because the values for the volume weight of winter wheat grain were not met. The economic profit of the research was the best in variant LAD + ENSIN, where were finally displayed transportation savings and amount of applied fertilisers.
78

Stanovení orgánové toxicity BRAF inhibitorů in vitro. / Determination of organ toxicity of BRAF inhibitors in vitro.

Miškovčíková, Zuzana January 2020 (has links)
Charles University Faculty of Pharmacy in Hradec Králové Department of Pharmacology & Toxicology Student: Zuzana Miškovčíková Supervisor: RNDr. Jana Maixnerová, PhD. Title of diploma thesis: Determination of organ toxicity of BRAF inhibitors in vitro. Malignant melanoma is one of the most serious skin diseases today. Therapy of advanced melanoma is difficult and often ineffective. BRAF inhibitors (dabrafenib and vemurafenib) have dramatically changed the results of melanoma treatment in the last few years. BRAF inhibitors are one of the most effective drugs against melanoma, but their clinical application is largely limited by drug resistance. Available clinical studies have shown an adverse nephrotoxic effect of BRAF inhibitors, but information on its mechanism is limited. Published studies further suggest that the toxic effect of BRAF inhibitors is primarily directed to podocytes located in the glomerular membrane. Thus, the aim of our study was to assess the cytotoxic effect of BRAF inhibitors on selected model renal cells in vitro in order to confirm the renal target toxicity. The main objective of the study was to analyse whether the nephrotoxic effect of BRAF inhibitors is specifically limited to podocytes or whether it can damage other renal cells. The experiments were performed on human cell lines...
79

Effects of Whole Body Vibration on Inhibitory Control Processes

Mortensen, Bennett Alan 03 June 2021 (has links)
Vibrations are often experienced in the workplace and may influence performance and executive function. Research has shown that vibrations may have an affect effect on drowsiness and tests related to inhibitory control. Previous work investigating whole body vibrations (WBV) and their effect was evaluated to inform the decisions for this study. WBV effects on cognitive abilities were examined and the different tests used in these studies were identified and compared. Electroencephalogram (EEG) and event related potentials (ERP) were selected to be used to measure inhibitory and cognitive processes. The N2 ERP, which reflects inhibitory control processes, was examined as well as the dominant frequency of the Fourier fast transform (FFT). A total of 94 participants between the ages of 18-55 (Mage = 20.49 SDage = 1.68) completed this study (51 female, 38 male and 5 with no gender listed). A go/no-go task was used to elicit the N2 ERP after WBV and a simultaneous EEG recording while the participants experienced WBV was used to gather the needed data. Stimulus frequencies used for the N2 ERP included 15 Hz, 20 Hz, and 40 Hz. During the simultaneous recording stimulus frequency varied every 30 seconds by 10 Hz from 20 Hz to 110 Hz. Data were analyzed using both a linear mixed effects model for normally distributed data and a generalized linear mixed effects model for data taken as percentages. It was hypothesized that there would be an effect on performance as measured in the raw go/no-go results, that this change in performance showing improved accuracy would be linked to inhibitory control, and be seen as a decrease in the magnitude of the N2 ERP. It was also hypothesized that the exploratory FFT portion of the study would produce a shift from a higher to a lower frequency in the dominant waveform . The results show that there were no main effects in either the behavioral performance or in the N2 ERP of the participants but that there was a significant interaction at 40 Hz with improved simple go trial activity and decreased no-go inhibition. The results also show that there was a statistically significant shift in neural oscillation activity but that this shift was not real-world relevant within the context of this study.
80

Serotonin Modulates Synaptic Transmission in Immature Rat Ventrolateral Medulla Neurons in Vitro

Hwang, L. L., Dun, N. J. 01 July 1999 (has links)
Patch-clamp recordings in whole-cell configuration were made from ventrolateral medulla neurons of brainstem slices from 8-12-day-old rats. 5- Hydroxytryptamine (3-30 μM) concentration-dependently suppressed excitatory and inhibitory postsynaptic currents evoked by focal stimulation. An augmentation of inhibitory synaptic currents by 5-hydroxytryptamine was noted in a small number of neurons. 5-Hydroxytryptamine depressed synaptic currents with or without causing a significant change in holding currents and membrane conductances; the inward or outward currents induced by exogenously applied glutamate or GABA/glycine were also not significantly changed by 5- hydroxytryptamine. In paired-pulse paradigms designed to evaluate a presynaptic site of action, 5-hydroxytryptamine suppressed synaptic currents but enhanced the paired-pulse facilitation. 5-Hydroxytryptamine reduced the frequency of miniature excitatory postsynaptic currents without significantly affecting the amplitude. 5-Carboxamidotryptamine, 8-hydroxy-2(di-n- propylamino)tetralin, sumatriptan and N-(3-trifluoromethylphenyl)piperazine which exhibit 5-hydroxytryptamine1 receptor agonist activity, depressed synaptic currents with different potencies, with 5-carboxamidotryptamine being the most potent. The non-selective 5-hydroxytryptamine1 receptor antagonist pindolol attenuated the presynaptic effect of 5-hydroxytryptamine, whereas the 5-hydroxytryptamine(1A) antagonist pindobind-5- hydroxytryptamine(1A) and 5-hydroxytryptamine2 receptor antagonist ketanserin were ineffective. Our results indicate that 5-hydroxytryptamine suppressed synaptic transmission in ventrolateral medulla neurons by activating presynaptic 5-hydroxytryptamine1 receptors, probably the 5- hydroxytryptamine(1B)/5-hydroxytryptamine(1D) subtype. In addition, 5- hydroxytryptamine augmented inhibitory synaptic currents in a small number of neurons the site and mechanism of this potentiating action are not known.

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