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An in vitro arterial flow bioreactor system for the generation of physiological flows in a biological environment was designed, constructed, and characterized. The design was based on models previously used to investigate the response of endothelial cells to shear. The model interfaces a bioreactor with flow elements to compose a flow loop that reproduces arterial flow conditions within the bioreactor. High-resolution (8.6 microns) time-resolved (4 ms) velocity field measurements within the bioreactor were obtained using Particle Image Velocimetry (PIV). Two physiological flows were considered, corresponding to medium human arteries at rest and exercise conditions: first, with an average Reynolds number of 150 and a Womersley parameter of 6.4, and second, with an average Reynolds number of 300 and a Womersley parameter of 9.0. Two cases were considered: first, using a smooth artery section, and second, with a confluent layer of human microvascular endothelial cells grown on the inner surface of the artery section. The instantaneous wall shear stress, time-averaged wall shear stress, and oscillatory shear index were computed from the velocity field measurements and compared for the cases with and without cells. These measurements were used to assess the value of the system for measurement of correlations between fluid dynamics and the response of biological tissue. It was determined that the flow present in such a system is not an accurate reproduction of physiological flow, and that direct measurement of the flow is necessary for accurate quantification of cellular response to fluid parameters. / Master of Science

PURPOSE: This study comparted arterial occlusion pressure (AOP) of the superficial femoral artery (SFA) between the dominant and nondominant legs and the relationship between blood flow and occlusion pressure at rest and during muscle contractions in males and females. METHODS: The AOP of the SFA was measured using Doppler ultrasound in the dominant and nondominant legs of 35 (16 males, 19 females) apparently healthy, normotensive young adults. Blood flow in the SFA was measured in the resting state (REST) and during plantar flexion exercise (EXC) at occlusion pressures ranging from 0% to 100% of AOP. ANOVA was used to compare AOP between the dominant and nondominant legs and between males and females. Regression analysis was used to evaluate the influence of relevant variables on AOP. A mixed model was used to evaluate the relationship between blood flow and occlusion pressure at REST and during EXC. RESULTS: There was a significant difference in the AOP between the dominant and nondominant legs in males (230 ± 41 vs 209 ± 37 mmHg) and females (191 ± 27 vs 178 ± 21 mmHg), respectively. There was also a significant sex difference in the AOP in the dominant (230 ± 41 vs 191 ± 27 mmHg; p = 0.002) and nondominant (209 ± 37 vs 178 ± 21 mmHg; p = 0.004) legs, respectively. Regression analysis revealed that after accounting for leg circumference, age, sex, blood pressure, and skinfold thickness were not independent predictors of AOP. At REST and during EXC, there was a linear relationship between relative blood flow and occlusion pressure. CONCLUSIONS: Differences in leg circumference contribute to a portion of the differences in AOP between the dominant and nondominant legs and between sexes. The linear relationship between relative blood flow and occlusion pressure suggests that occlusion pressures during blood flow restriction exercise should be chosen carefully. A large variance in blood flow measurements at different occlusion pressures suggests the need for evaluating the reliability of blood flow measurements and standardization of methods.

Veterinary medicine is benefitted by technological advances in diagnostic area by the spreading of scientific knowlagement. In order that new technologies may be used, information about normal standards for each type of examination is necessary, so that they may be used routinely and adequately prescribed for each patient. The Doppler ultrasound is beginning to be used in veterinary medicine for diverse purposes. The objectives of this study were to verify the Doppler ultrasound flow of the external ophthalmic artery in mixed breed cats anesthetized with tiletamine and zolazepam, and to correlate the average mean arterial pressure (MAP) surveyed by direct method in the same animals. There were used 20 mixed breed cats, both male and female, with body mass between 2 and 4 kilograms, proceeding from the Sociedade de Auxílio aos Animais de Umuarama - PR (SAAU). The animals received intra-muscular anesthesia with tiletamine and zolazepam (6,0 mg/kg). The femoral artery was assepticale cannulated and a manometer connected to an air column was connected to the catheter. The MAP was surveyed before and every 15 minutes until the end of the ultrasound examination. The flow of the external ophthalmic artery was measured through the ultrasond equipment Toshiba Powervision ATLHDI 3500, with an echo-doppler and a sectorial transducer of 6.0 MHz, directly applied to the cornea. Each eye had the artery flow surveyed by the equipment s own device, 3 samples being taken. The vascular resistance index was calculated based on the mean values of systolic and diastolic flow of each vasses. The values were tabulated and Student t test was applied to verify differences between the averages. Test of logistic regression was applied to the values of the MAP and the means of the artery flow to verify the correlation between the surveyed values. An average value for the MAP of 144.9 ± 26.68 mmHg and a flow of 14.28 ± 41.3 cm/sec for the external ophthalmic artery in the right eye in systole, 23.95 ± 11.46 cm/sec in diastole and 42.75 ± 12.64 cm/sec in the left eye in systole, 25.45 ± 9.61 cm/sec in diastole, were verified, there being no significant difference between the eyes. Correlation was not evidenced between the values of the MAP and the blood flow in the ophthalmic artery in both the eyes. The calculated index of vascular resistance was of 0.4175 ± 0.0774 for the external ophthalmic artery in the right eye and 0,4015 ± 0.0719 for the left eye, without any significant difference between the eyes. The results point to an intrinsic mechanism of flow control, controlled by local factors in the external ophthalmic artery. The values of the resistance index denote a low flow artery. Concluding, this study revealed the reference values, above cited, for the MAP and the blood flow in the external ophthalmic artery in mixed breed cats, anesthetized with tiletamine and zolazepam, and the information that there is no correlation between these values. / A medicina veterinária vem se beneficiando dos avanços tecnológicos dos meios diagnósticos em medicina, e da facilitação da divulgação da ciência. Para que novas tecnologias sejam utilizadas são necessárias informações acerca dos padrões normais para cada tipo de exame, para que se possa utilizá-lo na rotina e destiná-lo adequadamente para cada paciente. A fluxometria ultra-sonográfica está começando a ser utilizada em medicina veterinária com propósitos e fins diversos. Para destiná-la a um fim específico, o presente trabalho teve por objetivos verificar a fluxometria ultra-sonográfica da artéria oftálmica externa em gatos sem raça definida e anestesiados com tiletamina e zolazepam, e correlacioná-la à pressão arterial média aferida por método direto. Para tanto foram utilizados 20 gatos sem raça definida, entre machos e fêmeas, com massa corpórea entre 2 e 4 quilogramas, hígidos, provenientes da Sociedade de Amparo aos Animais de Umuarama - PR (SAAU). Os animais receberam anestesia intramuscular com tiletamina e zolazepam na dose de 6,0 mg/kg. A artéria femoral foi canulada de forma asséptica e um manômetro acoplado a uma coluna de ar foi conectada ao cateter, a PAM foi aferida antes e a cada 15 minutos até o término do exame ultra-sonográfico. A fluxometria da artéria oftálmica externa foi obtida através do equipamento de ultra-sonografia Toshiba Powervision ATL-HDI 3500, dotado de eco-doppler, com transdutor setorial de 6,0 MHz, aplicado diretamente sobre a córnea. Cada olho teve o fluxo de sua artéria aferido pelo programa do próprio aparelho, sendo tomadas 3 amostras. O índice de resistência vascular foi calculado com base nos valores do fluxo sistólico e diastólico médio de cada vaso. Os valores foram tabulados e teste t de Student foi aplicado para verificação de diferenças entre as médias. Teste de regressão logística foi aplicado aos valores da PAM e aos do fluxo em cada artéria, para verificar a existência de correlação entre os valores aferidos. Obteve-se um valor médio para a PAM de 144,9 ± 26,68 mmHg e uma velocidade de fluxo de 41,3 ± 14,28 cm/seg para a artéria oftálmica externa no olho direito em sístole, 23,95 ± 11,46 cm/seg em diástole e 42,75 ± 12,64 cm/seg no olho esquerdo em sístole, 25,45 ± 9,61 cm/seg em diástole, não existindo diferença significativa entre os olhos. Não foi constatada correlação entre os valores da PAM e o fluxo sangüíneo na artéria oftálmica em nenhum dos olhos. O índice de resistência vascular calculado foi de 0,4175 para a artéria oftálmica externa no olho direito e 0,4015 para a do olho esquerdo, sem diferença significativa entre os olhos. Os resultados apontam para um mecanismo intrínseco de controle do fluxo, controlado por fatores locais na artéria oftálmica externa. Os valores do índice de resistência denotam uma artéria de baixo fluxo. Como conclusão têm-se os valores de referência acima citados para a PAM e para o fluxo sangüíneo na artéria oftálmica externa em gatos sem raça definida anestesiados com tiletamina e zolazepam, e a informação de que não existe correlação entre esses valores.

yes / Purpose To characterize the intracranial volumetric changes that influence the cerebrospinal fluid (CSF) pulse in the Aqueduct of Sylvius (AoS). Materials and methods Neck MRI data were acquired from 12 healthy adults (8 female and 4 males; mean age = 30.9 years), using a 1.5 T scanner. The intracranial arterial, venous and CSF volumes changes, together with the aqueductal CSF (aCSF) volume, were estimated from flow rate data acquired at C2/C3 level and in the AoS. The correlations and temporal relationships among these volumes were computed. Results The aCSF volumetric changes were strongly correlated (r = 0.967, p < 0.001) with the changes in intracranial venous volume, whose peak occurred 7.0% of cardiac cycle (p = 0.023) before peak aCSF volume, but less correlated with the intracranial arterial and CSF volume changes (r = −0.664 and 0.676 respectively, p < 0.001). The intracranial CSF volume change was correlated with the intracranial venous volume change (r = 0.820, p < 0.001), whose peak occurred slightly before (4.2% of CC, p = 0.059). Conclusion The aCSF pulse is strongly correlated with intracranial venous volume, with expansion of the cortical veins occurring prior to aCSF flow towards the third ventricle. Both caudal-cranial aCSF flow and venous blood retention occur when arterial blood volume is at a minimum.