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Thesis (M.D.)--University of Hong Kong, 1990.

Thesis (M.D.)--University of Hong Kong, 1990. / Also available in print.

It was the purpose of this thesis to establish the functional level of the thyroid gland in patients with chronic ulcerative colitis.

Les petites protéines G de la famille Rho sont des régulateurs importants de la fonction cellulaire. Elles lient les signaux extracellulaires à l'activation de diverses voies de signalisation telles que celles menant à la phagocytose, la mitogénèse, l'adhésion cellulaire, l'expression génique, Toutefois leur fonction principale est l'assemblage et l'organisation du cytosquelette d'actine. Ces GTPases fonctionnent comme des interrupteurs moléculaires, actifs lorsque liés au GTP et inactifs sous la forme liée au GDP. <p><p>Le but de notre thèse est d'investiguer, dans les cellules thyroïdiennes de chien en culture primaire, l'implication des protéines de la famille Rho et de l'organisation du cytosquelette d'actine dans les actions diverses que la TSH exerce, via l'AMPc, sur la morphologie, la prolifération, la différenciation et la fonction des thyrocytes de chien en culture primaire.<p><p>Trois cascades conduisant à la mitogénèse coexistent dans la cellule thyroïdienne de chien: la voie de l'AMPc stimulée par la TSH ou la forskoline (activateur direct de l'adénylate cyclase), la voie des facteurs de croissance (tels que l'EGF, l'HGF) activant leur récepteur à activité tyrosine kinase et la cascade dépendante de la protéine kinase C activée par les esters de phorbol (TPA). Contrairement aux voies indépendantes de l'AMPc qui répriment l'expression des caractéristiques de différenciation, la cascade de l'AMPc stimule à la fois la prolifération, l'expression des gènes de l'état différencié et la fonction (iodation, formation d'H2O2, sécrétion hormonale).<p><p>Dans la cellule thyroïdienne de chien, les agents activant les cascades dépendantes et indépendantes de l'AMPc ont des effets différents sur l'organisation du cytosquelette d'actine. La TSH/AMPc et le TPA induisent une destruction des microfilaments d'actine et un "ruffling" membranaire, tandis que les autres agents (insuline, EGF, HGF, sérum) ne modifient pas le réseau de fibres d'actine (fibres de stress) présent dans les cellules quiescentes.<p><p>Parmi les protéines de la famille Rho, RhoA, Rac1 et Cdc42 sont les premières à avoir été identifiées et sont actuellement les mieux caractérisées. Nous montrons que la TSH, via l'AMPc, induit une diminution de la concentration de la forme active des protéines Rac1, Cdc42 et RhoA. En revanche, les autres agents mitogènes, tels que l'EGF et le TPA, qui activent des voies indépendantes de l'AMPc, n'affectent pas les taux de Rac1 et Cdc42 activés, mais augmentent le taux de RhoA-GTP. L'activation ou l'inactivation des protéines RhoA, Rac1 et Cdc42 est donc un nouvel élément distinguant les voies dépendantes et indépendantes de l'AMPc.<p><p>Grâce à deux toxines bactériennes, la toxine B qui inactive les protéines Rho et la toxine CNF1 qui au contraire les active, nous montrons que, dans les thyrocytes, celles-ci jouent un rôle critique dans l'organisation du cytosquelette, dans la transition G1-S, dans l'expression des gènes de différenciation Tg, ThOXs, NIS et TPO, mais pas dans la génération d'H2O2. <p><p>En effet, l'activité d'un ou plusieurs membres de cette famille est nécessaire à l'entrée des thyrocytes en phase S et à la phosphorylation de la protéine pRb, étape pré-requise à la transition G1-S. L'activation de ces protéines n'induit cependant pas, à elle seule, la prolifération. Nous mettons également en évidence l'existence d'un nouveau mécanisme par lequel ces protéines contrôleraient l'activité des complexes cycline D3-CDK4 indépendamment de leur assemblage. Par l'utilisation de la dihydrocytochalasine B, qui comme la toxine B via l'inactivation des Rhos, désorganise le cytosquelette, nous démontrons que l'intégrité de celui-ci n'est pas requise pour la progression des thyrocytes en phases G1 et S. L'inactivation des protéines Rho est par contre nécessaire à l'induction, par l'AMPc, de l'expression des gènes de différenciation incluant Tg, ThOXs, NIS et TPO, puisque ce processus est inhibé par la toxine CNF1. De plus, l'inactivation des Rhos par la toxine B, ainsi que le désassemblage des fibres de stress et du cytosquelette induit par la dihydrocytochalasine B, suffisent à imiter l'induction dépendante de l'AMPc de Tg et ThOXs, mais pas de NIS et TPO. La toxine B et la dihydrocytochalasine B imitent aussi l’effet de la voie TSH/AMPc sur l’accumulation de p27kip1. Enfin, nous montrons que l'augmentation de la production d'H2O2, nécessaire à la synthèse des hormones thyroïdiennes, ne requiert pas l'activité de la protéine Rac (ni des autres protéines de la famille Rho) alors que celle-ci joue un rôle déterminant dans la génération d'H2O2 dans le leucocyte. <p> / Doctorat en sciences, Spécialisation biologie moléculaire / info:eu-repo/semantics/nonPublished

Thesis (M.Med. (Radiation Oncology)) -- University of Limpopo, 2022 / Background Hypothyroidism in head and neck cancer patients after radiotherapy is known to occur, yet thyroid function tests are not routinely monitored in all patients post radiation therapy. Routine post radiation therapy thyroid function testing is currently not part of the follow-up protocol in these patients at Pietersburg Hospital. The aim of this study is to evaluate post radiation therapy hypothyroidism among head and neck cancer patients treated with radiotherapy at Pietersburg Hospital Methods A prospective (cohort) observational study was carried out among head and neck cancer patients receiving radiotherapy at the radiation oncology department in Pietersburg Hospital. Sample size of n=37 was calculated using Statistica V13.0. Thyroid function tests were performed at the start of radiation therapy and repeated on the first day of follow up, 6 weeks after completing radiation therapy. During follow up, participants were also interviewed for the presence of symptoms of hypothyroidism such as dry skin, dry hair, fatigue, cold intolerance, or weight gain. Data analysis was done with STATA version 16. Descriptive statistics were used to characterise variables, and summarised in tables, graphs and charts. Changes in thyroid function tests and other variables were analysed. A p-value of 0.05 was deemed statistically significant. Results Thirty-seven patients were enrolled in the study, 26 males and 11 females. The mean age of the patients was 53.1 ±12.3 standard deviation [SD]) with a range of 40.8 to 65.4 years. The most common diagnoses were cancer of the larynx and hypopharynx, forming 29.7% and oral cavity cancer, 29.7%. Only three patients (8%) had an early stage cancer (Stages 1 and 2), 11 patients (29.7%) moderately advanced cancer (Stage 3) while the majority (62%; n =23) had locally advanced cancer (Stage 4). Majority of the patients received 70Gy in 35 daily fractions, five fractions per week via 3-D conformal radiotherapy. Only 29 patients who had complete pre- and post radiotherapy thyroid function tests were included in the final analysis. Of these, none had clinical hypothyroidism at 3 months. Two patients (6.8%) had sub-clinical hypothyroidism, with post radiation therapy TSH values greater than 3.5mIU/ml. The mean post radiation therapy TSH values increased by 8.3% and the mean fT4 values decreased by 2.05% compared to the pre-radiation therapy values. Both changes were not statistically significant (p=0.99 and p=0.82 respectively). There was no statistically significant correlation between changes in TSH and fT4 versus age (p=0.88 and p=0.92 respectively), sex (p=0.55 and p=0.15 respectively), cancer stage (p=0.21 and p=0.78 respectively), and cancer site (p=0.17 and p=0.74 respectively). The most common post radiotherapy symptom was fatigue (62%) followed by cold intolerance (54%), weight gain (43%) and dry skin or dry hair (43% each). Conclusion The results of the study suggest that sub-clinical hypothyroidism is detectable early post radiation therapy presenting as clinical symptoms.

Introdução: Doenças tireoidianas subclínicas incluem hipotireoidismo e hipertireoidismo subclínicos. A associação entre doença tireoidiana subclínica e morbimortalidade cardiovascular é controversa e os dados sobre a relação entre essas condições clínicas e aterosclerose subclínica são escassos. Objetivos: Este estudo objetiva avaliar a associação entre doença tireoidiana subclínica, calcificação arterial coronariana (CAC), doença arterial coronariana (DAC), índice de espessura de médio-íntima carotídea média (IMT) e velocidade de onda de pulso carotídeo-femoral (cf-VOP) no Estudo Longitudinal de Saúde do Adulto (ELSA-Brasil). Métodos: Incluímos sujeitos eutireóideos, definidos como tendo TSH entre 0,4 e 4,0 mUI/L e T4L entre 0,8 e 1,9ng/dL, indivíduos com hipotireoidismo subclínico, definido como TSH > 4,0 mUI/L e T4L normal, e hipertireoidismo subclínico, definido como TSH < 0,4 mUI/L e T4L normal. Excluímos os indivíduos com as demais disfunções tireoidianas, em uso de medicação que altera a função tireoidiana, e com doença cardiovascular prévia. Na análise de angiotomografia, excluímos também os sujeitos com hipertireoidismo subclínico pelo pequeno número que impedia a análise e, na análise de cf-VOP, doença renal crônica, indivíduos em uso de diuréticos e de anti-hipertensivos. As associações entre quintis de TSH, CAC > 100 e DAC foram avaliadas por regressão logística e as associações entre IMT, VOP (como variáveis contínuas ou categorizadas com ponto de corte no percentil 75 amostral) e níveis de TSH ou doenças tireoidianas subclínicas foram avaliadas por regressões logísticas e lineares multivariadas. Todos os modelos foram ajustados por variáveis demográficas e fatores de risco cardiovasculares. Resultados: A análise de CAC incluiu 3.836 sujeitos, mediana de idade de 49 anos (IQR=44-56), 1.999 (52,1%) mulheres. CAC > 100 associou-se independentemente com o primeiro quintil (OR ajustado=1,57, IC 95%=1,05-2,35, P=0,027), usando o terceiro como referência. Na análise de angiotomografia, foram incluídos 796 sujeitos, mediana de idade de 55 anos (IQR=48-60 anos), 406 (51%) mulheres. O primeiro quintil associou-se independentemente com CAC (OR ajustado=1,76, IC 95%=1,09-2,82, P= 0,02), DAC (OR ajustado=1,73, IC 95%=1,08-2,79, P=0,023), mas não com extensão de doença. Na análise de IMT, foram incluídos 8.623 sujeitos, mediana de idade de 50 anos (IQR=45-57 anos), 4.624 (53,6%) mulheres, na subanálise de hipotireoidismo subclínico, e 8.193, com mediana de idade de 50 anos (IQR=44-57 anos), 4.382 (53,5%) mulheres, na subanálise de hipertireoidismo subclínico. Hipotireoidismo subclínico, mas não hipertireoidismo subclínico, associou-se ao IMT como variável contínua (beta=0,010, IC 95%=0,0004-0,019, P=0,041) e categorizado no percentil 75 ajustado para sexo, idade e raça (OR ajustado=1,30, IC95%=1,07-1,61, P=0,010). Na análise de cf-VOP, foram incluídos 8.341 sujeitos, mediana de idade de 50 anos (IQR=44-56 anos), 4.383 (52,5%) mulheres, na subanálise de hipotireoidismo subclínico, e 7.790, mediana de idade de 50 anos (IQR=44-57 anos), 4.191 (53,8%) mulheres, na subanálise de hipertireoidismo subclínico. Cf-VOP não se associou com doença tireoidiana subclínica. Conclusões: Em análises diferentes, CAC e DAC associaram-se com primeiro quintil de TSH usando-se o terceiro como referência. O IMT associou-se com hipotireoidismo subclínico e a cf-VOP não se associou com disfunção tireoidiana subclínica / Introduction: Subclinical thyroid disease includes subclinical hypothyroidism and subclinical hyperthyroidism. Association between subclinical thyroid disease and cardiovascular morbidity and mortality is controversial and data about the relationship between those clinical conditions and subclinical atherosclerosis is scarce. Objectives: This study aims to evaluate the association between subclinical thyroid disease, coronary artery calcification (CAC), coronary artery disease (CAD), mean common carotid intima-media thickness (IMT) and carotid-femoral pulse wave velocity (cf-PWV) in the Brazilian Longitudinal Study of Adult Health (ELSA-Brasil). Methods: We included euthyroid subjects, defined as TSH between 0.4 and 4.0 mIU/l and FT4 between 0.8 and 1.9 ng/dL, and individuals with subclinical hypothyroidism, defined as TSH > 4.0 mIU/l and normal FT4, and subclinical hyperthyroidism, defined as TSH < 0.4 mIU/L and normal FT4. We excluded individuals with other thyroid disorders, subjects who used medication that altered thyroid function, subjects with past of cardiovascular disease. In computed angiotomography analysis, we have excluded subjects with subclinical hyperthyroidism because of the small sample, and in cf-PWV analysis, we have excluded individuals with chronic kidney disease, use of anti-hypertensive and diuretics. The association between TSH quintiles was evaluated in logistic regression models for CAC and CAD, and the association between IMT, cf-PWV (as continuous variables or as factor, categorized at 75th sample\'s percentile) and TSH levels or subclinical thyroid diseases was evaluated by multivariate logistic and linear regression models. All models were adjusted for demographic variables and cardiovascular risk factors. Results: CAC analysis included 3,836 subjects, median of age 49 years (IQR=44-56), 1,999 (52.1%) women. CAC > 100 was independently associated with first quintile of TSH, using the third quintile as the reference (adjusted OR=1.57, 95% CI=1.05-2.35, P=0.027). Computed angiotomography analysis included 796 subjects, median of age 55 years (IQR=48-60), 406 (51%) women. CAD and CAC > 0 was independently associated with first quintile in comparison with third quintile (adjusted OR=1.73, 95% CI=1.08-2.79, P=0.023 and adjusted OR=1.76, 95% CI=1.09-2.82, P= 0.02, respectively), but not with burden of disease. In IMT analysis, 8,623 subjects were included, median of age 50 years (IQR=45-57 years), 4,624 (53.6%) women in the subclinical hypothyroidism subanalysis, and 8,193, median age 50 years (IQR = 44-57 years), 4,382 (53.5%) women, in the subclinical hyperthyroidism subanalysis. Subclinical hypothyroidism, but not subclinical hyperthyroidism, was independently associated with IMT as continuous variable (beta=0.010, IC 95%=0.0004-0.019, P=0.041) or as factor categorized at 75th percentile adjusted for age, sex and race (adjusted OR=1.30, 95% CI=1.07-1.61, P=0.010). In cf-PWV analysis, 8,341 subjects were included, median of age 50 years (IQR=44-56 years), 4,383 (52.5%) women in the subclinical hypothyroidism subanalysis, and 7,790, median age 50 years (IQR = 44-57 years), 4,191 (53.8%) women in subclinical hyperthyroidism subanalysis. Cf- PWV was not associated with subclinical thyroid disease. Conclusion: In separated analysis, CAC and CAD was independently associated with first quintile of TSH using the third as the reference; IMT was independently associated with subclinical hypothyroidism, and cf-PWV was not associated with subclinical thyroid diseases

Introdução: Doenças tireoidianas subclínicas incluem hipotireoidismo e hipertireoidismo subclínicos. A associação entre doença tireoidiana subclínica e morbimortalidade cardiovascular é controversa e os dados sobre a relação entre essas condições clínicas e aterosclerose subclínica são escassos. Objetivos: Este estudo objetiva avaliar a associação entre doença tireoidiana subclínica, calcificação arterial coronariana (CAC), doença arterial coronariana (DAC), índice de espessura de médio-íntima carotídea média (IMT) e velocidade de onda de pulso carotídeo-femoral (cf-VOP) no Estudo Longitudinal de Saúde do Adulto (ELSA-Brasil). Métodos: Incluímos sujeitos eutireóideos, definidos como tendo TSH entre 0,4 e 4,0 mUI/L e T4L entre 0,8 e 1,9ng/dL, indivíduos com hipotireoidismo subclínico, definido como TSH > 4,0 mUI/L e T4L normal, e hipertireoidismo subclínico, definido como TSH < 0,4 mUI/L e T4L normal. Excluímos os indivíduos com as demais disfunções tireoidianas, em uso de medicação que altera a função tireoidiana, e com doença cardiovascular prévia. Na análise de angiotomografia, excluímos também os sujeitos com hipertireoidismo subclínico pelo pequeno número que impedia a análise e, na análise de cf-VOP, doença renal crônica, indivíduos em uso de diuréticos e de anti-hipertensivos. As associações entre quintis de TSH, CAC > 100 e DAC foram avaliadas por regressão logística e as associações entre IMT, VOP (como variáveis contínuas ou categorizadas com ponto de corte no percentil 75 amostral) e níveis de TSH ou doenças tireoidianas subclínicas foram avaliadas por regressões logísticas e lineares multivariadas. Todos os modelos foram ajustados por variáveis demográficas e fatores de risco cardiovasculares. Resultados: A análise de CAC incluiu 3.836 sujeitos, mediana de idade de 49 anos (IQR=44-56), 1.999 (52,1%) mulheres. CAC > 100 associou-se independentemente com o primeiro quintil (OR ajustado=1,57, IC 95%=1,05-2,35, P=0,027), usando o terceiro como referência. Na análise de angiotomografia, foram incluídos 796 sujeitos, mediana de idade de 55 anos (IQR=48-60 anos), 406 (51%) mulheres. O primeiro quintil associou-se independentemente com CAC (OR ajustado=1,76, IC 95%=1,09-2,82, P= 0,02), DAC (OR ajustado=1,73, IC 95%=1,08-2,79, P=0,023), mas não com extensão de doença. Na análise de IMT, foram incluídos 8.623 sujeitos, mediana de idade de 50 anos (IQR=45-57 anos), 4.624 (53,6%) mulheres, na subanálise de hipotireoidismo subclínico, e 8.193, com mediana de idade de 50 anos (IQR=44-57 anos), 4.382 (53,5%) mulheres, na subanálise de hipertireoidismo subclínico. Hipotireoidismo subclínico, mas não hipertireoidismo subclínico, associou-se ao IMT como variável contínua (beta=0,010, IC 95%=0,0004-0,019, P=0,041) e categorizado no percentil 75 ajustado para sexo, idade e raça (OR ajustado=1,30, IC95%=1,07-1,61, P=0,010). Na análise de cf-VOP, foram incluídos 8.341 sujeitos, mediana de idade de 50 anos (IQR=44-56 anos), 4.383 (52,5%) mulheres, na subanálise de hipotireoidismo subclínico, e 7.790, mediana de idade de 50 anos (IQR=44-57 anos), 4.191 (53,8%) mulheres, na subanálise de hipertireoidismo subclínico. Cf-VOP não se associou com doença tireoidiana subclínica. Conclusões: Em análises diferentes, CAC e DAC associaram-se com primeiro quintil de TSH usando-se o terceiro como referência. O IMT associou-se com hipotireoidismo subclínico e a cf-VOP não se associou com disfunção tireoidiana subclínica / Introduction: Subclinical thyroid disease includes subclinical hypothyroidism and subclinical hyperthyroidism. Association between subclinical thyroid disease and cardiovascular morbidity and mortality is controversial and data about the relationship between those clinical conditions and subclinical atherosclerosis is scarce. Objectives: This study aims to evaluate the association between subclinical thyroid disease, coronary artery calcification (CAC), coronary artery disease (CAD), mean common carotid intima-media thickness (IMT) and carotid-femoral pulse wave velocity (cf-PWV) in the Brazilian Longitudinal Study of Adult Health (ELSA-Brasil). Methods: We included euthyroid subjects, defined as TSH between 0.4 and 4.0 mIU/l and FT4 between 0.8 and 1.9 ng/dL, and individuals with subclinical hypothyroidism, defined as TSH > 4.0 mIU/l and normal FT4, and subclinical hyperthyroidism, defined as TSH < 0.4 mIU/L and normal FT4. We excluded individuals with other thyroid disorders, subjects who used medication that altered thyroid function, subjects with past of cardiovascular disease. In computed angiotomography analysis, we have excluded subjects with subclinical hyperthyroidism because of the small sample, and in cf-PWV analysis, we have excluded individuals with chronic kidney disease, use of anti-hypertensive and diuretics. The association between TSH quintiles was evaluated in logistic regression models for CAC and CAD, and the association between IMT, cf-PWV (as continuous variables or as factor, categorized at 75th sample\'s percentile) and TSH levels or subclinical thyroid diseases was evaluated by multivariate logistic and linear regression models. All models were adjusted for demographic variables and cardiovascular risk factors. Results: CAC analysis included 3,836 subjects, median of age 49 years (IQR=44-56), 1,999 (52.1%) women. CAC > 100 was independently associated with first quintile of TSH, using the third quintile as the reference (adjusted OR=1.57, 95% CI=1.05-2.35, P=0.027). Computed angiotomography analysis included 796 subjects, median of age 55 years (IQR=48-60), 406 (51%) women. CAD and CAC > 0 was independently associated with first quintile in comparison with third quintile (adjusted OR=1.73, 95% CI=1.08-2.79, P=0.023 and adjusted OR=1.76, 95% CI=1.09-2.82, P= 0.02, respectively), but not with burden of disease. In IMT analysis, 8,623 subjects were included, median of age 50 years (IQR=45-57 years), 4,624 (53.6%) women in the subclinical hypothyroidism subanalysis, and 8,193, median age 50 years (IQR = 44-57 years), 4,382 (53.5%) women, in the subclinical hyperthyroidism subanalysis. Subclinical hypothyroidism, but not subclinical hyperthyroidism, was independently associated with IMT as continuous variable (beta=0.010, IC 95%=0.0004-0.019, P=0.041) or as factor categorized at 75th percentile adjusted for age, sex and race (adjusted OR=1.30, 95% CI=1.07-1.61, P=0.010). In cf-PWV analysis, 8,341 subjects were included, median of age 50 years (IQR=44-56 years), 4,383 (52.5%) women in the subclinical hypothyroidism subanalysis, and 7,790, median age 50 years (IQR = 44-57 years), 4,191 (53.8%) women in subclinical hyperthyroidism subanalysis. Cf- PWV was not associated with subclinical thyroid disease. Conclusion: In separated analysis, CAC and CAD was independently associated with first quintile of TSH using the third as the reference; IMT was independently associated with subclinical hypothyroidism, and cf-PWV was not associated with subclinical thyroid diseases