This thesis was based on a collection of my published works. Chapter 1 introduced the idea that infections, both acute and chronic, were risk factors for stroke. Various infections and micro-organisms associated with stroke were discussed. Specifically, the relationship between micro-organisms such as Cytomegalovirus, Helicobacter pylori, dental pathogens, and stroke were discussed. The theories of the pathogenesis of atherosclerosis were presented. Chapter 1 also reviewed the association between Chlamydia pneumoniae, an atypical respiratory pathogen, and atherosclerosis in detail. Chapter 2 introduced the ‘Chlamydia pneumoniae in elderly patients with stroke’ or ‘C-PEPS’ study from which published works in subsequent chapters of this thesis were based. The C-PEPS was a case-control study that investigated the seroprevalence of C pneumoniae in 100 elderly acute stroke and transient ischaemic attack (TIA) patients versus 87 control medical patients. The C-PEPS study showed a high seroprevalence (immunoglobulin IgG) of C pneumoniae infection in both cases and controls. There was no significant association between C pneumoniae seropositivity and stroke / TIA. Chapter 3 presented a study that investigated the reproducibility of a commercial enzyme linked immunosorbent assay (ELISA) kit (SeroCP, Savyon) used in the CPEPS study. The study concluded that SeroCP ELISA had a good reproducibility for the detection of C pneumoniae IgA and moderately good reproducibility for C pneumoniae IgG and IgM. In chapter 4, the ‘Mycoplasma pneumoniae in elderly patients with stroke’ or ‘MPEPS’ case-control study was based on the same cohort of patients as in the C-PEPS study. The M-PEPS study showed a high seroprevalence of M pneumoniae, another atypical respiratory pathogen, in the cohort. However, the study had ruled out M pneumoniae as a major risk factor for stroke / TIA. In chapter 5, the ‘Legionella pneumophila in elderly patients with stroke’ or ‘L-PEPS’ was another case-control study based on the same cohort of patients as in the C-PEPS 3 study. The L-PEPS study established that there was no statistical difference between the seroprevalence of L pneumophila, another atypical respiratory pathogen, in both the stroke / TIA patients and control medical patients. However, when the results of C-PEPS, M-PEPS and L-PEPS studies were analysed together, it appeared that the aggregate number or infectious burden of chronic atypical respiratory infections was associated with the risk of stroke / TIA. Chapter 6 presented a pilot study that investigated the seroprevalence of Coxiella burnetii, another atypical respiratory pathogen, in the same cohort of patients as in the C-PEPS study. Due to very low seropositivity and zero counts, a conclusion could not be made on any association between C burnetii seropositivity and stroke / TIA. Chapter 7 presented the electrocardiographic findings such as rhythms and ischaemic changes of the same cohort of patients as in the C-PEPS study. Atrial fibrillation was the commonest rhythm abnormality in both elderly stroke / TIA cases and medical controls. After adjusment for background history of ischaemic heart disease, there was a statistical trend to suggest an association between ischaemic elctrocardiographic changes and stroke / TIA. Chapter 8 presented a case-control study that investigated the relationsips between socioeconomic deprivation (SED) status, atypical respiratory infections and survival outcome in the same cohort of patients as in the C-PEPS study. The SED status of stroke / TIA cases and controls were similar. Although an association between acute atypical respiratory infection and SED was only found in the control medical patients, acute atypical respiratory infectious burden was found to associate with income deprivation in the whole cohort of elderly stroke / TIA and medical patients. SED on its own had only a modest effect on the association between chronic atypical respiratory infectious burden and stroke / TIA. Elderly patients’ duration of survival after an acute stroke / TIA appeared not to be affected by their background SED status. Chapter 9 was the concluding chapter. The main findings of the published works submitted for the thesis were summarised and discussed. Some directions for future research were also discussed.

Thesis. 1978. Ph.D.--Massachusetts Institute of Technology. Dept. of Electrical Engineering and Computer Science. / MICROFICHE COPY AVAILABLE IN ARCHIVES AND ENGINEERING. / Vita. / Bibliography: leaves 266-276. / Ph.D.

Thesis (B.S.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 1979. / MICROFICHE COPY AVAILABLE IN ARCHIVES AND ENGINEERING. / Includes bibliographical references. / by David Howard Turkel. / B.S.

Uma função autonômica adequada é essencial para a manutenção da estabilidade hemodinâmica durante a hemorragia. Diversos estudos tem demonstrado que a análise da variabilidade da frequência cardíaca (VFC) é uma técnica não-invasiva promissora para avaliação da modulação autonômica no trauma, mostrando haver uma associação entre a VFC e desfecho clínico. O objetivo deste estudo foi avaliar a VFC durante o choque hemorrágico e reposição volêmica, comparando a variáveis hemodinâmicas e metabólicas tradicionais. Vinte porcos anestesiados e ventilados mecanicamente foram submetidos ao choque hemorrágico (60% da volemia estimada) e avaliados durante 60 minutos sem reposição volêmica. Os animais sobreviventes foram tratados com solução de Ringer lactato e avaliados por mais 180 minutos. Medidas de VFC (no domínio do tempo e da frequência) e variáveis hemodinâmicas e metabólicas foram comparados entre animais sobreviventes e não sobreviventes. Sete dos 20 animais morreram durante o choque hemorrágico e reposição volêmica inicial. Todos os animais apresentaram diminuição do intervalo RR e aumento das medidas de VFC no domínio do tempo durante a hemorragia, sendo restaurados os valores basais após reposição volêmica. Embora não significante estatisticamente, foram observados diminuição de LF e LF/HF durante os estágios iniciais de sangramento, recuperação dos valores basais durante a manutenção do choque hemorrágico e aumento após reposição volêmica. Os animais não sobreviventes apresentaram valores significativamente menores de pressão arterial média (43 ± 7 vs 57 ± 9) e índice cardíaco (1,7 ± 0,2 vs 2,6 ± 0,5) e valores maiores de lactato (7,2 ± 2,4 vs 3,7 ± 1,4), excesso de base (-6,8 ± 3,3 vs -2,3 ± 2,8) e potássio sérico (5,3 ± 0,6 vs 4,2 ± 0,3), trinta minutos após indução do choque hemorrágico. Concluímos que as medidas de VFC não foram capazes de discriminar sobreviventes e não-sobreviventes durante choque hemorrágico. As variáveis metabólicas e hemodinâmicas foram melhores em refletir a gravidade do choque hemorrágico do que as medidas de VFC / An adequate autonomic function is essential for maintaining the hemodynamic stability during hemorrhage. The analysis of heart rate variability (HRV) has been shown as a promising non-invasive technique for assessing the cardiac autonomic modulation in trauma, and several studies have demonstrated the association between HRV and clinical outcome. The aim of this study was to evaluate HRV during hemorrhagic shock and fluid resuscitation, comparing to traditional hemodynamic and metabolic parameters. Twenty anesthetized and mechanically ventilated pigs were submitted to hemorrhagic shock (60% of estimated blood volume) and evaluated for 60 minutes without fluid replacement. Surviving animals were treated with Ringer solution and evaluated for an additional period of 180 minutes. HRV metrics (time domain and frequency domain) as well as hemodynamic and metabolic parameters were evaluated in survivors and non-survivors animals. Seven of the 20 animals died during hemorrhage and initial fluid resuscitation. All animals presented an increase in time-domain HRV measures during haemorrhage and fluid resuscitation restored baseline values. Although not significantly, normalized low-frequency and LF/HF ratio decreased during early stages of haemorrhage, recovering baseline values later during hemorrhagic shock and increased after fluid resuscitation. Non-surviving animals presented significantly lower mean arterial pressure (43 ± 7 vs 57 ± 9) and cardiac index (1.7 ± 0.2 vs 2.6 ± 0.5) and higher levels of plasma lactate (7.2 ± 2.4 vs 3.7 ± 1.4), base excess (-6.8 ± 3.3 vs -2.3±2.8) and potassium (5.3 ± 0.6 vs 4.2 ± 0.3), 30 minutes after hemorrhagic shock compared to surviving animals. Conclusions: The HRV metrics were not able to discriminate survivors from non-survivors during hemorrhagic shock. Moreover, metabolic and hemodynamic variables were more reliable to reflect hemorrhagic shock severity than HRV metrics

Thesis. 1976. M.S.--Massachusetts Institute of Technology. Dept. of Electrical Engineering and Computer Science. / Microfiche copy available in Archives and Engineering. / Includes bibliographical references. / M.S.

La electrocardiografía es una herramienta básica diagnóstica en la medicina veterinaria de animales de compañía, siendo la mejor alternativa para evaluar la actividad eléctrica del corazón en forma no invasiva. Sin embargo, cambios en el posicionamiento del paciente pueden ocasionar cambios en las medidas del complejo PQRST y desencadenar diagnósticos errados. El propósito de este estudio fue detectar posibles variaciones de la dirección del eje eléctrico medio cuando el registro se hace en posición decúbito lateral izquierdo en lugar de la posición estándar en decúbito lateral derecho, para analizar la variación en los resultados de acuerdo al posicionamiento del paciente. El estudio se realizó en 100 canes aparentemente sanos de ambos sexos, mayores a 1 año de edad y de cualquier peso. Se registraron dos electrocardiogramas por cada paciente: decúbito lateral derecho e izquierdo, que luego fueron analizados uno por uno; los resultados del cálculo del eje eléctrico medio fueron comparados, llegando a la conclusión que no son similares y que la posición decúbito lateral derecho es irreemplazable para el cálculo del eje eléctrico medio cardiaco en caninos.Electrocardiography is a basic diagnostic tool in veterinary medicine pet, being the best non-invasively alternative to assess the electrical activity of the heart. However, changes in patient positioning may cause changes in measures of PQRST complex and trigger misdiagnoses. The purpose of this study was to detect possible changes in the direction of the mean electrical axis when the register is in left lateral position (LL) instead of the standard right lateral position (RL), to analyze the variation in results according to patient positioning. The study was conducted in 100 apparently healthy male and female dogs, older than 1 year of age and of any weight. Two electrocardiograms were registered for each patient: right and left lateral decubitus, which were then analyzed one by one; two electrocardiograms were performed for each patient the results of the calculation of the average electrical axis were compared, concluding that they are not similar and that the right lateral decubitus position is irreplaceable for calculating mean electrical axis of the heart in dogs.

A doença renal policística autossômica dominante (DRPAD) felina é caracterizada pela presença de múltiplos cistos localizados em parênquima renal e, ocasionalmente, hepáticoe pancreático, sendo uma importante causa de doença renal crônica terminal. Ela é considerada a enfermidade congênita hereditária mais prevalente dos gatos domésticos, porém, os dados epidemiológicos eclínicos existentes no Brasil são escassos, o que torna o seu controle mais difícil no país. Da mesma forma, a DRPAD em humanos constitui-se na doença renal monogênica mais comum, acometendo 1 em cada 400 a 1.000 indivíduos, com curso clínico muito semelhante a doença em gatos.No presente estudo, 252 felinos da raça Persa e mestiços de Persa do Estado de São Paulo foram avaliados através de teste genético para DRPAD. Os resultados indicaram uma prevalência de apenas 6,35% de gatos portadores da mutação para DRPAD em heterozigose, valor abaixo dos índices registrados em outros países. Do total de animais, uma coorte de 82 felinos da região metropolitana de São Paulo foi selecionada para realização de exames físico, laboratoriais, imagenológicos e genéticos. Estes animais foram separados em dois grupos de acordo com a presença (n=12) ou ausência (n=70) de alterações ultrassonográficas sugestivas de doença renal policística.A sensibilidade e a especificidade entre o teste molecular e o exame ultrassonográfico para DRPAD nos animais estudados foram ambas de 100%. Os animais com alterações genéticas e ultrassonográficas indicativas de doença renal policística autossômica dominante apresentaram aumento significativo no valor de cálcio total sérico, fração de excreção urinária de cálcio e de sódio(p=0,0219; p=0,0275; p=0,0032, respectivamente). Os demais parâmetros clínicos e laboratoriais não diferiram entre os dois grupos de animais. O exame ecocardiográfico revelou que casos de hipertrofia miocárdica foram mais frequente entre os animais positivos para DRPAD (p=0,0001). Dessa forma, é possível concluir que exames de triagem ultrassonográfica e/ou molecular devem ser utilizados para o diagnóstico de animais com DRPAD, visto que, alterações clínicas e laboratoriais sã o tardias. Exames eletro e ecocardiográficos devem ser rotineiramente realizados nos felinos císticos. Ainda, a caracterização clínica da DRPAD em gatos ressalta não apenas sua grande importância para medicina felina, mas também para a comunidade médica devido à correlação com a doença humana, representando um modelo ortólogo espontâneo, em animal de porte médio, para o estudo dessa enfermidade e validação de novos procedimentos terapêuticos. / Autosomal dominant polycystic kidney disease (ADPKD) in feline is characterized by the presence of multiple cists located in the renal parenchyma and occasionally, in liver and pancreas, and is an important cause of terminal chronic renal disease. It is considered worldwide as the most prevalent congenital illness in domestic cats. However, in Brazil the epidemiological and clinical data are barely existent, which difficultythe control of the disease. In the same way, the human ADPKD is the most common monogenic kidney disease. It affects 1 in every 400 to 1000 individuals, with a clinical course very similar to the disease in feline. In this research, 252 Persians and crossbreed cats from São Paulo state were assessed through the genetic test for ADPKD. The results indicated a prevalence of only 6.35% of cats carring the mutation for ADPKD in heterozygosis. This value is below the indexes reported in other countries. A cohort of 82 cats was selected in the metropolitan region of São Paulo to perform physical, laboratory, imaging and genetic tests. These animals were divided into two groups according to the presence (n = 12) or absence (n = 70) of ultrasound changes suggestive of polycystic kidney disease. The sensitivity and specificity between molecular tests and ultrasonography exam for ADPKD in the sample were both 100%. The animals with ultrasonography and genetic modifications, indicatives of ADPKD, presented a significant increase in the amount of total serum calcium, urinary fractional excretion of calcium and sodium(p=0,0219; p=0,0275; p=0,0032, respectively). Other clinical and laboratory parameters did not differ between the two groups of animals with and without the disease. Echocardiographic examination revealed that cases of myocardial hypertrophy were more frequent among animals positive for ADPKD (p = 0.0001). In conclusion, ultrasound exams and/ or molecular screening should be used to diagnostic animals with ADPKD, since the clinical and laboratory abnormalities are late. Electrocardiography and echocardiography examinations should be routinely performed in cystic cats. Still, the clinical characterization of ADPKD in cats not only highlights its importance to feline medicine, but also for the medical community due to the correlation with human disease, as an ortholog spontaneous model for the study of this disease.

A doença renal policística autossômica dominante (DRPAD) felina é caracterizada pela presença de múltiplos cistos localizados em parênquima renal e, ocasionalmente, hepáticoe pancreático, sendo uma importante causa de doença renal crônica terminal. Ela é considerada a enfermidade congênita hereditária mais prevalente dos gatos domésticos, porém, os dados epidemiológicos eclínicos existentes no Brasil são escassos, o que torna o seu controle mais difícil no país. Da mesma forma, a DRPAD em humanos constitui-se na doença renal monogênica mais comum, acometendo 1 em cada 400 a 1.000 indivíduos, com curso clínico muito semelhante a doença em gatos.No presente estudo, 252 felinos da raça Persa e mestiços de Persa do Estado de São Paulo foram avaliados através de teste genético para DRPAD. Os resultados indicaram uma prevalência de apenas 6,35% de gatos portadores da mutação para DRPAD em heterozigose, valor abaixo dos índices registrados em outros países. Do total de animais, uma coorte de 82 felinos da região metropolitana de São Paulo foi selecionada para realização de exames físico, laboratoriais, imagenológicos e genéticos. Estes animais foram separados em dois grupos de acordo com a presença (n=12) ou ausência (n=70) de alterações ultrassonográficas sugestivas de doença renal policística.A sensibilidade e a especificidade entre o teste molecular e o exame ultrassonográfico para DRPAD nos animais estudados foram ambas de 100%. Os animais com alterações genéticas e ultrassonográficas indicativas de doença renal policística autossômica dominante apresentaram aumento significativo no valor de cálcio total sérico, fração de excreção urinária de cálcio e de sódio(p=0,0219; p=0,0275; p=0,0032, respectivamente). Os demais parâmetros clínicos e laboratoriais não diferiram entre os dois grupos de animais. O exame ecocardiográfico revelou que casos de hipertrofia miocárdica foram mais frequente entre os animais positivos para DRPAD (p=0,0001). Dessa forma, é possível concluir que exames de triagem ultrassonográfica e/ou molecular devem ser utilizados para o diagnóstico de animais com DRPAD, visto que, alterações clínicas e laboratoriais sã o tardias. Exames eletro e ecocardiográficos devem ser rotineiramente realizados nos felinos císticos. Ainda, a caracterização clínica da DRPAD em gatos ressalta não apenas sua grande importância para medicina felina, mas também para a comunidade médica devido à correlação com a doença humana, representando um modelo ortólogo espontâneo, em animal de porte médio, para o estudo dessa enfermidade e validação de novos procedimentos terapêuticos. / Autosomal dominant polycystic kidney disease (ADPKD) in feline is characterized by the presence of multiple cists located in the renal parenchyma and occasionally, in liver and pancreas, and is an important cause of terminal chronic renal disease. It is considered worldwide as the most prevalent congenital illness in domestic cats. However, in Brazil the epidemiological and clinical data are barely existent, which difficultythe control of the disease. In the same way, the human ADPKD is the most common monogenic kidney disease. It affects 1 in every 400 to 1000 individuals, with a clinical course very similar to the disease in feline. In this research, 252 Persians and crossbreed cats from São Paulo state were assessed through the genetic test for ADPKD. The results indicated a prevalence of only 6.35% of cats carring the mutation for ADPKD in heterozygosis. This value is below the indexes reported in other countries. A cohort of 82 cats was selected in the metropolitan region of São Paulo to perform physical, laboratory, imaging and genetic tests. These animals were divided into two groups according to the presence (n = 12) or absence (n = 70) of ultrasound changes suggestive of polycystic kidney disease. The sensitivity and specificity between molecular tests and ultrasonography exam for ADPKD in the sample were both 100%. The animals with ultrasonography and genetic modifications, indicatives of ADPKD, presented a significant increase in the amount of total serum calcium, urinary fractional excretion of calcium and sodium(p=0,0219; p=0,0275; p=0,0032, respectively). Other clinical and laboratory parameters did not differ between the two groups of animals with and without the disease. Echocardiographic examination revealed that cases of myocardial hypertrophy were more frequent among animals positive for ADPKD (p = 0.0001). In conclusion, ultrasound exams and/ or molecular screening should be used to diagnostic animals with ADPKD, since the clinical and laboratory abnormalities are late. Electrocardiography and echocardiography examinations should be routinely performed in cystic cats. Still, the clinical characterization of ADPKD in cats not only highlights its importance to feline medicine, but also for the medical community due to the correlation with human disease, as an ortholog spontaneous model for the study of this disease.

Sudden Cardiac Death (SCD) is the largest cause of natural deaths in the USA, accounting for over 300,000 deaths annually. The major reason for SCD is Ventricular Arrhythmia (VA). Therefore, there is need for exploration of approaches to predict increased risk for VA. Alternans of the T wave in the ECG (TWA) is widely investigated as a potential predictor of VA, however, clinical trials show that TWA has high negative predictive value but poor positive predictive value. A possible reason that TWA has a large number of false positives is that a pattern of alternans known as concordant alternans, may not be as arrhythmogenic as another pattern which is discordant alternans. Currently, it is not possible to discern the pattern of alternans using clinical ECGs. Prior studies from our group have showed that alternans of the maximum rate of depolarization of an action potential also can occur when Action Potential Duration (APD) alternans occurs and the relationship between these two has the potential to create spatial discord. These results suggest that exploration of the co-occurrence of depolarization and repolarization alternans has the potential to stratify the outcome of TWA tests. In order to investigate the link between depolarization alternans and changes in ECGs, we used a mathematical model created previously in our research group which simulated ECGs from the cellular level changes observed in our experimental studies. These results suggest that the changes in ECGs should appear as alternating pattern of the amplitude of the R wave. Because there are a variety of factors which may also cause the R wave amplitude to change, we used signal analysis and statistical modeling to determine the link between the observed changes in R wave amplitude and depolarization alternans. Results from ECGs recorded from patients show that amplitude of the R wave can change as predicted by our experimental results and mathematical model. Using TWA as the marker of repolarization alternans and R Wave Amplitude Alternans (RWAA) as the marker of depolarization alternans, we investigated the phase relation between depolarization and repolarization alternans in clinical grade ECG and observed that this relationship does change spontaneously, consistent with our prior results from animal studies. Results of the present study support further investigation of the use of RWAA as a complementary method to TWA to improve its positive predictive value.

Bibliography: leaves 284-298 / 4 microfiches (339 fr.) : / Title page, contents and abstract only. The complete thesis in print form is available from the University Library. / Summary: Shows that foetal acidosis is related to prolongation of the QT interval, a change which cannot be accounted for in foetal heart rate. Describes the configuration and time constants of the foetal electrocardiogram both during labour and at the time of delivery in normal and acidotic subjects. Confirms that foetal acidosis during labour is associated with acidosis at the time of delivery and with clinical depression of the newborn infant / Thesis (M.D.)--Dept. of Obstetrics and Gynaecology, University of Adelaide, 1970