Diss. (sammanfattning) Stockholm : Karol. inst. / Härtill 5 uppsatser.

Investigation into the molecular basis of diabetes-induced erectile dysfunction was carried out on corpus cavernosum tissue from control and streptozotocin (STZ)-induced diabetic rats. Increased expression of endothelial nitric oxide synthase (eNOS) and increased nitrosative stress was found in the diabetic penile tissue. Diabetic neuropathy is associated with a failure in axonal regeneration. <i>In vitro</i> axon growth, guidance and regeneration model systems were used to study both the intrinsic nature of diabetic DRG neurones to grow and respond to guidance cues, but also to study the supportive properties of the diabetic nerve environment for axon regeneration. Cyclic Adenosine-3’5-Monophosphate (cAMP) signalling is compromised in diabetic DRG neurones. Increasing cAMP in diabetic neurones reduced the deficit in neurite growth and reversed the aberrant response of diabetic neuronal growth cones to the cAMP-dependent trophic factor, nerve growth factor (NGF). Diabetic neurones display reduced expression of Exchange protein activated by cAMP (Epac), a downstream effector of cAMP. Specifically activating Epac also rescued the abnormal turning responses of diabetic DRG neurones. Impaired axonal regeneration in diabetes has been, in part, attributed to delayed Wallerian degeneration. Using the cryoculture bioassay, it was shown that during regeneration the peripheral nerve environment, of both control and diabetic rats are equally supportive for axon growth. In summary, this is the first study to imply that specific signalling mechanisms, involving the cAMP-Epac pathway, may be compromised in neurones from diabetic rats, which contribute towards reduced neurite growth and abnormal responses to axon guidance cues.

Neuropathy is a major complication that affects nearly half of all patients with diabetes, greatly decreasing their quality of life. Patients experience a wide range of symptoms including pain, numbness, weakness and other morbidities. While its pathogenesis has been the focus of extensive research, there are still few effective treatment options available for this disease. The discovery of novel molecular targets underlying this diabetic neuropathy may lead to the development of new, more effective therapeutics. DLC2, a Rho GTPase-activating protein with specific activity for RhoA, was shown to be involved in pain signaling. Mice deficient for this protein (DLC2-/-) have increased RhoA activity in their peripheral nerves, and have heightened pain responses compared to wild type (DLC2+/+) in acute pain tests, displaying increased sensitivity to noxious thermal and inflammatory stimuli. DLC2-/- mice also show elevated blood glucose levels, lower body weight and increased sensitivity to blood glucose compared to wild type. Because of the hyperalgesia to acute pain displayed by DLC2-/- mice compared to wild type, and since the RhoA pathway is known to be involved in the pathogeneses and maintenance of diabetes and its complications, these mice were used to investigate more clinically relevant, chronic pain in a model of diabetic neuropathy. Streptozotocin (STZ), given in multiple low doses over five days (MLDS treatment), was used to induce diabetes in DLC2+/+ and DLC2-/- mice, and their pain responses were tested 8 weeks later. Diabetic DLC2-/- mice (DLC2-/--STZ) were hyperalgesic to thermal stimuli from the hot plate test compared to diabetic DLC2 wild type mice (DLC2+/+-STZ) and vehicle-treated controls of both genotypes (DLC2-/--Veh and DLC2+/+-Veh. Similar responses were seen from the von Frey filament test, where the DLC2-/--STZ group exhibited mechanical allodynia compared to the DLC2+/+-STZ group and both control groups. Dorsal root ganglia (DRG) were dissected from these four groups of mice for qPCR screening and protein analysis. DLC2-/--STZ mice showed significantly higher gene expression of the voltage-gated sodium channel Nav 1.9 compared to DLC2+/+-STZ mice, while there was a strong trend of increased levels in the DLC2-/--STZ group compared to both non-diabetic groups. Western blot analysis of the DRG from these mice shows increased levels of COX-2 expression of DLC2-/--STZ mice compared to DLC2+/+-Veh, and elevated levels of phosphorylated ERK (pERK) in DLC2-/--Veh and both diabetic groups compared to DLC2+/+-Veh. Overall, diabetic DLC2-/- mice have more severe painful diabetic neuropathy, with thermal hyperalgesia and mechanical allodynia. Increased RhoA activity and pERK, which are known to be involved in regulation, transcription and trafficking of sodium channels, may lead to increased Nav1.9 mRNA levels and activation. Localized mainly to nociceptors of the DRG, Nav1.9 is known to play a role in sensitizing neurons through lowering the threshold for action potentials, possibly leading to the observed heightened pain response. Additionally, elevated COX-2 levels in DLC2-/--STZ mice may lead to further deficits through activation of inflammatory responses. Future studies will further investigate how these mechanisms are involved in the altered pain response from diabetes. / published_or_final_version / Anatomy / Master / Master of Philosophy

Thesis (Ph. D.)--University of Hawaii at Manoa, 2005. / Includes bibliographical references (leaves 116-154).

Thesis (M.Sc.)--York University, 2005. Graduate Programme in Kinesiology and Health Science. / Typescript. Includes bibliographical references. Also available on the Internet. MODE OF ACCESS via web browser by entering the following URL: http://gateway.proquest.com/openurl?url%5Fver=Z39.88-2004&res%5Fdat=xri:pqdiss &rft_val_fmt=info:ofi/fmt:kev:mtx:dissertation&rft_dat=xri:pqdiss:MR11734

published_or_final_version / Molecular Biology / Master / Master of Philosophy

Thesis (M. Phil.)--University of Hong Kong, 1998. / Includes bibliographical references (leaves 124-144).

Made available in DSpace on 2014-06-11T19:22:49Z (GMT). No. of bitstreams: 0 Previous issue date: 2011-12-16Bitstream added on 2014-06-13T20:49:20Z : No. of bitstreams: 1 fortaleza_acs_me_prud.pdf: 477345 bytes, checksum: f49debf4b9a2f0a76c98e9512ad369eb (MD5) / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) / O objetivo do estudo foi verificar a estabilidade do ato de locomoção em diabéticos com neuropatia periférica, em três situações: marcha habitual com os olhos abertos; marcha com os olhos fechados e marcha com olhos abertos e diminuição da base de sustentação. Participaram do estudo 41 indivíduos, sendo 18 do grupo neuropata e 23 do grupo controle (GC). A avaliação da estabilidade foi realizada por meio de um baropodômetro associado ao software Footwalk Pro. Os dados obtidos foram: velocidade da marcha e porcentagens de tempo de duplo apoio e de apoio simples. Foram encontradas diferenças significantes nas três situações entre os grupos para a velocidade e tempo de apoio simples, com diminuição para o grupo neuropata (p<0,05), e tempo de duplo apoio, com aumento para esse grupo (p<0,05) em todas as condições. Para os dados de velocidade, tempo de duplo apoio e tempo de apoio simples, a condição de olho aberto foi diferente da condição de olho fechado (p=0,001) e da condição com diminuição da base de sustentação (p=0,001). Foi possível observar que nas três situações avaliadas, o grupo neuropata apresentou déficit na estabilidade do ato de locomoção e tal desempenho foi ainda mais comprometido nas duas situações que exigiam mais do controle postural. Tais modificações da marcha, decorrentes da complexidade imposta pelas diferentes condições, sugerem a inserção destas na avaliação e no tratamento dessa população / The aim of this study was to verify the stability of the act of locomotion in diabetics with peripheral neuropathy in three situations: habitual gait with eyes opened, gait with eyes closed, and gait with eyes opened and reduced base of support. The study included 41 subjects: 18 of the neuropathic group and 23 in the control group. The stability was evaluated by baropodometry platform associated with the software Footwalk Pro. Data were obtained: gait speed and percentual of double stance time and single stance time. Significant differences were found in the three cases between the groups in the data of gait speed and single stance time, with a larger reduction for neuropathic group (p<0,05) and increased in double stance time in the neuropathic group (p<0,05) in all conditions. For data of gait speed measure, double stance time and single stance time, the condition eyes opened was different from eyes closed (p=0,001) and from the condition with reduced base of support (p=0,001). It was observed that in the three situations evaluated, the neuropathic group showed stability locomotion deficit and the performance was more injured in both situations that required more postural control. Such gait modifications, due to the complexity imposed by different conditions, suggest the inclusion of these in the evaluation and treatment of this population

published_or_final_version / Molecular Biology / Doctoral / Doctor of Philosophy

Includes bibliographical references and index.