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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.
161

Produção estratégica de insumos nucleares para a saúde no Brasil: o caso do FDG-18 F / Health nuclear strategic production in Brazil: FDG-18F case

Élide Mendes Guimarães 03 September 2010 (has links)
No Brasil, a difusão de conceitos da física nuclear na área médica ganhou destaque ao longo da última década com o uso do FDG-18F, substância análoga à glicose marcada radioativamente para atuar em procedimentos de diagnóstico e tratamento em oncologia, neurologia e cardiologia. Das três especialidades é no uso oncológico que estão suas aplicações de maior relevância como a detecção precoce de metástase e outras formas de monitoramento tumoral que resultam em maiores chances de sobrevida ao paciente. Estas possibilidades passaram a fazer parte da realidade nacional com a incorporação da tecnologia híbrida de PET-CT, equipamento gerador de imagens anatômicas e metabólicas para mapeamento preciso de lesões por meio da concentração de FDG-18F. O uso médico deste composto ganhou tamanha repercussão que a necessidade de expandir a oferta de FDG-18F para além dos bolsões geográficos contemplados pela produção pública culminou na aprovação de emenda constitucional que abriu o mercado de radiofármacos no país. O presente estudo aborda a formação da cadeia produtiva de radiofármacos irradiados em cíclotron a partir da quebra do monopólio de produção e comercialização de radioisótopos de meia-vida curta, em 2006, para demonstrar que, ao consolidar a cadeia produtiva de FDG-18F, instituições e atores sociais nela envolvidos constituíram um subsistema nacional de inovação em saúde / In Brazil, nuclear physics concepts become prominent in healthcare throughout the last decade with FDG-18F use, a glucose similar substance radioactively marked to be used in diagnosis and treatment procedures in oncology, neurology and cardiology, but it´s in oncology treatments that we can find the biggest relevance application with the early cancer metastasis detection and many other cancerous tumor monitoring forms that may be revert in patient life time gain. PET-CT hybrid technology incorporation made these possibilities become part of national reality. The equipment is able to produce integrated anatomical and metabolic images that shows tiny tissue damages tracking FDG-18F concentration. This medical composition become renowned enough to claim loud for geographic offer expansion until it raised a new law allowing private initiative taking part in radiopharmaceuticals production market. This research intent to describe the cyclotron radiopharmaceuticals irradiated supply chain building up process since productive and commercial public monopoly broke up in 2006, so then it will be able to prove that a new innovative healthcare subsystem has resulted by the social actors and institutions efforts to establish FDG-18F supply chain
162

Estudos de aterosclerose experimental utilizando tomografia por emissão de pósitrons (PET-Scan) / Studies of experimental atherosclerosis using pósitron emission tomography (PET-Scan).

Kazuma, Soraya Megumi 24 May 2017 (has links)
A aterosclerose é caracterizada como uma doença imune-inflamatória crônica das artérias devido ao grande acúmulo de lipídios na íntima. Um dos fatores envolvidos na progressão da aterosclerose é a presença de uma subfração de partículas de lipoproteína de baixa densidade (LDL) com um grau mínimo de modificação, denominada LDL eletronegativa [LDL(-)], que possui propriedades pró-inflamatórias, apresenta maior retenção na íntima das artérias e maior tempo de permanência na circulação sanguínea, gerando respostas imuno-inflamatórias. Epítopos de anticorpos monoclonais importantes no reconhecimento das partículas de LDL(-) foram mapeados por phage display, gerando peptídeos mimotopos (P1A3 e P2C7) com potencial para acompanhamento da progressão da aterosclerose, sendo excelentes candidatos como radiotraçadores marcados com emissores de pósitrons para obtenção de imagens moleculares por tomografia por emissão de pósitrons (PET) associada à tomografia computadorizada (PET/CT). O peptídeo P1A3 foi radiomarcado com 64Cu através da complexação com o quelante DOTA, obtendo-se imagens por PET/CT da captação do peptídeo na região do arco aórtico de camundongos knockout para a apolipoproteína E (Apoe-/-) comparados com animais controle sem lesões ateroscleróticas. Antes da obtenção das imagens PET/CT, os peptídeos radiomarcados foram validados através de estudos de estabilidade e biodistribuição, acumulando-se rapidamente nos rins. Também foi sintetizado um nanocluster de ouro, marcado com 64Cu e funcionalizado com P1A3 em sua superfície, observando-se o maior direcionamento dos nanoclusters de ouro ligados ao P1A3 para a região das lesões ateroscleróticas do arco aórtico de camundongos Apoe-/-, comparado ao nanocluster controle. Os peptídeos P1A3 e P2C7 radiomarcados com 68Ga, foram também avaliados por imagens PET/CT em camundongos knockout para o gene do receptor da LDL (LDLr-/-) tratados ou não com dieta hipercolesterolêmica. As imagens PET/CT mostraram que os peptídeos marcados com 68Ga tiveram um aumento de captação na região do arco aórtico de camundongos LDLr-/- hipercolesterolêmicos em relação ao controle. Além disso, P2C7 foi radiomarcado com 99mTc e sua biodistribuição demonstrou uma relação maior de % atividade injetada (AI)/órgão da aorta/coração nos camundongos hipercolesterolêmicos, em concordância com a imagem obtida por SPECT (tomografia computadorizada por emissão de fóton único) que revelou maior captação no arco aórtico. / Atherosclerosis is characterized as a chronic immune-inflammatory disease of the large arteries due to the accumulation of lipids in the intima. One of the factors involved in the progression of atherosclerosis is the presence of a subfraction of low-density lipoprotein (LDL) particles with a minimum degree of modification, called electronegative LDL [LDL (-)], which has proinflammatory properties, retention in the intima of the arteries and longer residence time in the blood circulation, generating immune-inflammatory responses. Epitopes of monoclonal antibodies important for the recognition of LDL(-) particles were mapped by phage display, generating mimotope peptides (P1A3 and P2C7) with potential to monitor the progression of atherosclerosis. These peptides are excellent candidates as radiotracers labeled with positron emitters to obtain molecular images by positron emission tomography (PET) associated with computed tomography (PET/CT). The P1A3 peptide was radiolabeled with 64Cu by complexation with the DOTA chelator to obtain PET/CT images of the peptide uptake in the aortic arch of apoliprotein E knockout mice (Apoe-/-) compared to control animals without atherosclerotic lesions. Prior to PET/CT imaging, radiolabeled peptides were validated by stability and biodistribution studies that indicated rapid accumulation in the kidneys. It was also synthesized a gold nanocluster, labeled with 64Cu and functionalized with P1A3 on its surface, observing the greater targeting of gold nanoclusters bound to P1A3 in the region of the atherosclerotic lesions of the aortic arch of Apoe-/- mice, compared to control nanocluster. The P1A3 and P2C7 peptides radiolabeled with 68Ga were also evaluated by PET imaging in LDL receptor gene knockout mice (LDLr-/-) treated or not with a hypercholesterolemic diet. PET/CT images showed that the 68Ga-labeled peptides had increased uptake in aortic arch of LDLr-/- hypercholesterolemic mice in relation to the control. Furthermore, the biodistribution of 99mTc-radiolabeled P2C7 showed a higher %ID (injected dose)/organ ratio of aorta/heart in hypercholesterolemic mice that was in accordance to SPECT (single photon emission computed tomography) imaging showing its higher uptake in the aortic arch.
163

Social Phobia. From Epidemiology to Brain Function

Furmark, Tomas January 2000 (has links)
<p>Social phobia is a disabling anxiety disorder characterized by an excessive fear of negative evaluation in social situations. The present thesis explored the epidemiology and neurobiology of the disorder. By means of a mailed questionnaire, the point prevalence of social phobia in the Swedish general population was estimated at 15.6%. However, prevalence rates varied between 1.9 and 20.4% across the different levels of distress and impairment used to define cases. Thus, although social anxiety is widespread within the community, the precise diagnostic boundaries for social phobia are difficult to determine. Social phobia was associated with female gender, low educational attainment, psychoactive medication use, and lack of social support. A cluster analysis revealed that subtypes of social phobia mainly differed dimensionally on a mild-moderate-severe continuum, with number of cases declining with increasing severity. Public speaking was the most common social fear in all groups of social phobics and in the population at large.</p><p>In the neurobiological studies, positron emission tomography was used to examine brain serotonin metabolism and changes in the regional cerebral blood flow (rCBF) response to public speaking stress following treatment with a selective serotonin reuptake inhibitor (SSRI) or cognitive-behavioral group therapy. Social phobics exhibited lowered serotonin turnover, relative to non-phobics, mainly in the medial temporal cortex including the bilateral rhinal and periamygdaloid regions. Symptom improvement with cognitive-behavioral- as well as SSRI-treatment was accompanied by a reduced rCBF-response to public speaking in the amygdala, hippocampus and adjacent temporal cortex, i.e. regions that serve important functions in anxiety. Thorough suppression of rCBF in limbic brain regions was associated with favorable long-term treatment outcome. These results provide neuroimaging evidence for a presynaptic serotonergic dysfunction in social phobia and for a common neural mechanism whereby psychological and pharmacological anti-anxiety treatments act.</p>
164

Imaging and Quantification of Brain Serotonergic Activity using PET

Lundquist, Pinelopi January 2006 (has links)
<p>This thesis investigates the potential of using positron emission tomography (PET) to study the biosynthesis and release of serotonin (5HT) at the brain serotonergic neuron. As PET requires probe compounds with specific attributes to enable imaging and quantification of biological processes, emphasis was placed on the evaluation of these attributes. </p><p>The experiments established that the 5HT transporter radioligand [<sup>11</sup>C]-3-amino-4-(2-dimethylaminomethyl-phenylsulfanyl)-benzonitrile, [<sup>11</sup>C]DASB, is suitable for imaging and quantification of transporters in rats and rhesus monkeys. In addition, the binding of [<sup>11</sup>C]DASB in brain tissue is decreased when 5HT concentrations are increased by tranylcypromine administration. The sensitivity of [<sup>11</sup>C]DASB binding, under these experimental conditions, to increased endogenous 5HT concentrations demonstrates the potential of in vivo monitoring of 5HT release in rat and monkey models.</p><p>The irreversible binding of 5-hydroxy-L-[β-<sup>11</sup>C]tryptophan, [<sup>11</sup>C]HTP, in the monkey brain was lower in the presence of NSD1015, which was used to inhibit the decarboxylase step in 5HT synthesis. [<sup>11</sup>C]HTP seems thus to have potential for tracking changes in the activity of this biosynthesis enzyme. In contrast, the accumulation of [<sup>11</sup>C]HTP was unaffected by clorgyline, which was used to inhibit metabolism of the probe in the brain. This appears to indicate that elimination of the main metabolite from the brain could be negligible and thus will not alter [<sup>11</sup>C]HTP quantification. The extent and distribution of the irreversible binding of a substrate for the first enzyme in 5HT formation, α-[<sup>11</sup>C]methyl-L-tryptophan, [<sup>11</sup>C]AMT, was different from those for [<sup>11</sup>C]HTP. This suggests that the two studied probe compounds provide estimates related to the enzyme activity of different steps in the 5HT biosynthesis pathway. </p><p>A reference tissue version of the Patlak method for the analysis of data obtained by PET was also developed. This approach takes into account irreversible binding in the reference region and appears, therefore, to yield more reliable parameter estimates than the conventional reference Patlak analysis. The method is recommended for parameter estimation of [<sup>11</sup>C]HTP data when no metabolite-corrected plasma curve is available. </p><p>Knowledge of altered 5HT synthesis and release in disease states and the consequences for effective pharmacotherapy can improve our knowledge of the aetiology of certain psychiatric and neurological diseases and enhance our ability to design more effective drugs.</p>
165

Genetical and Clinical Studies in Wilson's Disease

Waldenström, Erik January 2007 (has links)
<p>Wilson’s disease is a rare inborn error of metabolism caused by a defect in ATP7B, a protein necessary for proper copper excretion into bile. It is characterised by copper accumulation with hepatic and central nervous system dysfunction.</p><p>We investigated 24 Swedish families with Wilson’s disease by sequencing the entire coding sequence using a new technique called manifold sequencing. Disease causing mutations were found in 44 out of 48 alleles.</p><p>From data obtained in the first study, the two most common mutations (C3207A and C2930T) were sought in 2640 anonymous DNA samples from a Swedish population, using a pooling strategy and solid-phase minisequencing. Four C3207A and one C2930T were found. From the number of C3207A, a prevalence of Wilson’s disease in Sweden of about 1 in 110,000 could be estimated.</p><p>Four groups with three patients each had four different genotypes concerning mutations in ATP7B. The patients’ psychopathological symptoms were investigated, using the Karolinska Scales of Personality rating (KSP) and Comprehensive Psychopathological Rating Scale (CPRS). A trend towards lower CPRS scores was seen in the groups with mutations known to render ATP7B completely without activity.</p><p>Using <sup>61</sup>Cu liver PET in patients homozygous for mutations in ATP7B, heterozygotes, normal individuals and two patients with alcoholic liver cirrhosis, significantly slower uptake was seen in the homozygotes as compared to the heterozygotes and normal individuals. The patients with cirrhosis had values in between. This implies that <sup>61</sup>Cu liver PET might be used as an additional rapid and little invasive diagnostic tool in Wilson’s disease.</p><p>In a retrospectively studied cohort consisting of 363 patients followed in Sweden and the UK, nine cases of aggressive intra-abdominal malignancies were seen, which is more than expected. Caution should be taken in the follow-up of Wilson’s disease patients.</p>
166

Radiolabelled Oligonucleotides for Evaluation of in vivo Hybridisation Utilising PET Methodology

Lendvai, Gábor January 2007 (has links)
<p>Antisense oligonucleotides (ODN) may interfere in gene expression on the basis of hybridising to its complementary messenger RNA (mRNA) sequence in the cell thereby preventing the synthesis of the peptide. Therefore, these ODNs may be potential drugs to treat human diseases by “knocking down” the expression of responsible genes or correcting the maturation process of mRNA in the field called antisense therapy. Moreover, antisense ODNs upon labelling are also potential imaging agents to monitor gene expression <i>in vivo</i>, i.e. to accomplish <i>in vivo</i> hybridisation. This would provide a non-invasive tool compared to present methods, which require tissue samples. </p><p>This goal may be reached using positron emission tomography (PET) methodology. PET is a most advanced <i>in vivo</i> imaging technology, which would allow exploring the fate of radionuclide-labelled antisense ODNs in the body; thereby providing information about biodistribution and quantitative accumulation in tissues to assess pharmacokinetic properties of ODNs. This kind of evaluation is important as part of the characterisation of antisense therapeutics but also as part of the development of antisense imaging agents.</p><p>The present study aimed to investigate <sup>76</sup>Br- and <sup>68</sup>Ga-labelled ODNs of five different modifications: phosphodiester, phosphorothioate, 2'-<i>O</i>-methyl phosphodiester, locked nucleic acid (LNA), and peptide nucleic acid. The study included exploration of the hybridisation abilities of these ODNs after labelling; furthermore, the biodistribution, metabolite analysis and uptake of the ODNs in rats regarding non-hybridisation and hybridisation specific uptake was conducted. Among the ODNs studied, LNA-DNA mixmer (LNA and DNA nucleotides in alternation along the sequence) displayed the most promising characteristics considering a higher retention in tissues, stability and longer plasma residence. However, biodistribution data demonstrated a non-hybridisation specific distribution in rat tissues with kidney, liver, spleen and bone marrow being the organs of high uptake. Scavenger receptors or other saturable processes unrelated to hybridisation may play a role in tissue uptake and in clearance of antisense ODNs through these organs. These processes may be sequence dependent suggesting that proof of <i>in vivo</i> hybridisation through imaging needs much more elaborate evaluations than just comparison of sense and antisense sequences and proving dose-dependency.</p>
167

Social Phobia. From Epidemiology to Brain Function

Furmark, Tomas January 2000 (has links)
Social phobia is a disabling anxiety disorder characterized by an excessive fear of negative evaluation in social situations. The present thesis explored the epidemiology and neurobiology of the disorder. By means of a mailed questionnaire, the point prevalence of social phobia in the Swedish general population was estimated at 15.6%. However, prevalence rates varied between 1.9 and 20.4% across the different levels of distress and impairment used to define cases. Thus, although social anxiety is widespread within the community, the precise diagnostic boundaries for social phobia are difficult to determine. Social phobia was associated with female gender, low educational attainment, psychoactive medication use, and lack of social support. A cluster analysis revealed that subtypes of social phobia mainly differed dimensionally on a mild-moderate-severe continuum, with number of cases declining with increasing severity. Public speaking was the most common social fear in all groups of social phobics and in the population at large. In the neurobiological studies, positron emission tomography was used to examine brain serotonin metabolism and changes in the regional cerebral blood flow (rCBF) response to public speaking stress following treatment with a selective serotonin reuptake inhibitor (SSRI) or cognitive-behavioral group therapy. Social phobics exhibited lowered serotonin turnover, relative to non-phobics, mainly in the medial temporal cortex including the bilateral rhinal and periamygdaloid regions. Symptom improvement with cognitive-behavioral- as well as SSRI-treatment was accompanied by a reduced rCBF-response to public speaking in the amygdala, hippocampus and adjacent temporal cortex, i.e. regions that serve important functions in anxiety. Thorough suppression of rCBF in limbic brain regions was associated with favorable long-term treatment outcome. These results provide neuroimaging evidence for a presynaptic serotonergic dysfunction in social phobia and for a common neural mechanism whereby psychological and pharmacological anti-anxiety treatments act.
168

Genetical and Clinical Studies in Wilson's Disease

Waldenström, Erik January 2007 (has links)
Wilson’s disease is a rare inborn error of metabolism caused by a defect in ATP7B, a protein necessary for proper copper excretion into bile. It is characterised by copper accumulation with hepatic and central nervous system dysfunction. We investigated 24 Swedish families with Wilson’s disease by sequencing the entire coding sequence using a new technique called manifold sequencing. Disease causing mutations were found in 44 out of 48 alleles. From data obtained in the first study, the two most common mutations (C3207A and C2930T) were sought in 2640 anonymous DNA samples from a Swedish population, using a pooling strategy and solid-phase minisequencing. Four C3207A and one C2930T were found. From the number of C3207A, a prevalence of Wilson’s disease in Sweden of about 1 in 110,000 could be estimated. Four groups with three patients each had four different genotypes concerning mutations in ATP7B. The patients’ psychopathological symptoms were investigated, using the Karolinska Scales of Personality rating (KSP) and Comprehensive Psychopathological Rating Scale (CPRS). A trend towards lower CPRS scores was seen in the groups with mutations known to render ATP7B completely without activity. Using 61Cu liver PET in patients homozygous for mutations in ATP7B, heterozygotes, normal individuals and two patients with alcoholic liver cirrhosis, significantly slower uptake was seen in the homozygotes as compared to the heterozygotes and normal individuals. The patients with cirrhosis had values in between. This implies that 61Cu liver PET might be used as an additional rapid and little invasive diagnostic tool in Wilson’s disease. In a retrospectively studied cohort consisting of 363 patients followed in Sweden and the UK, nine cases of aggressive intra-abdominal malignancies were seen, which is more than expected. Caution should be taken in the follow-up of Wilson’s disease patients.
169

Radiolabelled Oligonucleotides for Evaluation of in vivo Hybridisation Utilising PET Methodology

Lendvai, Gábor January 2007 (has links)
Antisense oligonucleotides (ODN) may interfere in gene expression on the basis of hybridising to its complementary messenger RNA (mRNA) sequence in the cell thereby preventing the synthesis of the peptide. Therefore, these ODNs may be potential drugs to treat human diseases by “knocking down” the expression of responsible genes or correcting the maturation process of mRNA in the field called antisense therapy. Moreover, antisense ODNs upon labelling are also potential imaging agents to monitor gene expression in vivo, i.e. to accomplish in vivo hybridisation. This would provide a non-invasive tool compared to present methods, which require tissue samples. This goal may be reached using positron emission tomography (PET) methodology. PET is a most advanced in vivo imaging technology, which would allow exploring the fate of radionuclide-labelled antisense ODNs in the body; thereby providing information about biodistribution and quantitative accumulation in tissues to assess pharmacokinetic properties of ODNs. This kind of evaluation is important as part of the characterisation of antisense therapeutics but also as part of the development of antisense imaging agents. The present study aimed to investigate 76Br- and 68Ga-labelled ODNs of five different modifications: phosphodiester, phosphorothioate, 2'-O-methyl phosphodiester, locked nucleic acid (LNA), and peptide nucleic acid. The study included exploration of the hybridisation abilities of these ODNs after labelling; furthermore, the biodistribution, metabolite analysis and uptake of the ODNs in rats regarding non-hybridisation and hybridisation specific uptake was conducted. Among the ODNs studied, LNA-DNA mixmer (LNA and DNA nucleotides in alternation along the sequence) displayed the most promising characteristics considering a higher retention in tissues, stability and longer plasma residence. However, biodistribution data demonstrated a non-hybridisation specific distribution in rat tissues with kidney, liver, spleen and bone marrow being the organs of high uptake. Scavenger receptors or other saturable processes unrelated to hybridisation may play a role in tissue uptake and in clearance of antisense ODNs through these organs. These processes may be sequence dependent suggesting that proof of in vivo hybridisation through imaging needs much more elaborate evaluations than just comparison of sense and antisense sequences and proving dose-dependency.
170

Brain processing of experimental muscle pain and its interrelation with proprioception and muscle fatigue : positron emission tomography study

Korotkov, Alexander January 2005 (has links)
Chronic muscle pain is a significant medical and social problem and better understanding of the pathophysiological mechanisms involved is an important requirement for further development of diagnostics, treatment and rehabilitation methods. Experimental imaging studies have investigated functional neuroanatomy of different pain components. However, several aspects of brain mechanisms underlying brain processing of muscle pain remain unclear. The general goal of the present thesis was to study functional brain anatomy of systems underlying perception of muscle pain, processing of proprioceptive information and maintenance of fatiguing muscle contractions with an emphasize on their possible interrelations. Four series of experiment were carried out. Using an injection of hypertonic saline (HS) into the m. triceps to induce pain comparable with clinical muscle pain a significant activation of insula and putamen as well as decrease of activity in the temporal and occipital cortex in comparison with control stimulation were revealed. An advanced model of prolonged muscle pain were provided by the infusion of the HS during 20 minutes into m. erector spinae A complex dynamics of brain activity during the habituation to nociceptive stimulation was shown: initial activation of insula changed to decrease of activity in this and several other cortical areas. A conjunction analysis identified activations jointly significant in both experiments (despite localization of HS nociceptive stimulation) in the right insula, occipital and left parietal cortical areas. The study of brain activity in response to different modalities of prorioceptive inputs – passive movements, kinesthetic illusions and muscle vibration showed corresponding different patterns of activation in motor and somatosenory areas and temporal areas. Finally, the study of sustained isometric muscle contractions of various force levels and durations revealed that muscle fatigue is associated with contralateral activation of the motor and somatosensory areas and temporal areas and bilateral activation in the supplementary motor areas and cingular cortex, indicating that increased efforts needed to maintain required force and its eventual breakdown with fatigue might induce activation of additional cortical areas. Analysis of data obtained in all experimental series revealed that insula, secondary somatosensory and auditory areas are activated during both perception of muscle pain and processing of somatosensory afferentation. In conclusion, this thesis has elucidated brain processing of muscle pain showing distributed, bilateral patterns comprised of activated structures predominantly attributed to the medial pain system and deactivated structures. Furthermore, initial and late phases of tonic muscle pain are associated with different brain reactions, namely initial activation of the insula followed by a significant bilateral decrease of activity at the late stage. Area of brain cortex located near lateral sulcus and comprised of secondary somatosensory cortex, posterior part of the insula and adjacent auditory cortex is engaged in the perception of muscle pain and processing of somatosensory afferentation as well as maintenance of fatiguing muscle contractions.

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