Several research studies indicate the increasing problem obesity has become over the past few decades (Andersen 1999:41; Fox, 1999:56-60; Kuczmarshi et al., 1994:205-212). Obesity, after cigarette smoke, is the leading cause of death in the USA and a combination of diet factors and physical inactivity (two primary contributors of obesity) leads to an average of 300,000 deaths per year (McGinnis & Foege, 1993:2207-2212). Previously little information was available on the effect of obesity on the peripheral vascularization, and even less about the effect of obesity on arterial compliance (Raison et al., 1998:299-303). Research indicated a decrease in arterial compliance with an increase in body weight (Kumaran et al., 2002:7; Sutton-Tyrrell et al., 2001:431; Tounian et al., 2001:1400-1404; Stepniakowski & Egan, 1995:R567) however, contradictory research where no association between obesity and arterial compliance was indicated, has also been found (Singhal et al., 2002:1920; Mangoni et al., 1995:986). Mackey et al. (2002:16) also found that an increased aortic stiffness is positively associated with lowered physical activity levels. A lifestyle consisting of moderate physical activity, has a positive effect on the health, lowering of chronic illness risks, the prevention of cardiovascular diseases and the improvement of quality of lie in overweight and obese patients (Adams et al., 2003542; Ferreira et al., 2003:1670-1678; Macera, 2003:123; Mclnnis, 200396; Kolden et al., 2002:447). Moderate aerobic exercise is also seen as a potential non-pharmaceutical therapeutic method to increase age associated decrease in arterial compliance in young, middle aged and older adults (Gates et al., 2003:2213; Havlik et al., 2003:156; Seals, 2003:68; Moreau et al., 2003:865; Joyner, 2000:1214; Cameron et al., 1999:653). The objective of this study was firstly to determine the correlation between obesity and vascular function in Caucasian women between the ages 19 and 56 and to determine which marker of obesity is the best predictor of a weakened vascular function (see article one). The second objective was to determine the correlation between physical activity, obesity and arterial compliance in Caucasian women between the ages 19 and 56 years (see article 2). A total of 115 Caucasian women were recruited to participate in this study. Anthropometric measurements and a comprehensive body composition profile was taken using the BOD POD. The Finometer apparatus was used to measure the arterial compliance and the sphygmomanometer to measure the subjects blood pressure. The subjects completed the Yale Physical Activity Survey questionnaire to determine their physical activity index. This study seems to indicate a positive relationship between arterial compliance and obesity which could be explained by the influence blood volume had in determining arterial compliance. A negative correlation was found between obesity and blood pressure where an increase in obesity caused an increase in both systolic and diastolic blood pressure. A positive correlation was found between physical activity and obesity. The higher the activity levels were in this study, the less obese the subjects tended to be. No correlation was found between physical activity and arterial compliance. A clear trend, even though no statistically significant differences, was found between physical activity and blood pressure. The more active the subjects were, the lower their blood pressure tended to be. / Thesis (M.Sc. (Human Movement Science))--North-West University, Potchefstroom Campus, 2005

A heuristic approach to the application of bandwidth-oriented signal coordination is proposed based on a system partition technique. The proposed approach divides a large signalized arterial into subsystems based on clustering results considering factors such as block distance and turning movements. Each subsystem is optimized to achieve the maximum bandwidth efficiency. Evaluation of the system includes two parts, THOS (through opportunity) comparison and simulation evaluation. Two case studies are presented to illustrate how the proposed approach can be applied, and the influence of clustering method on signal coordination is presented with comparison of three scenarios, no partition, 2 clusters and 3 clusters. Evaluation of the case study shows that clustering method is beneficial in improving progression bandwidth, bandwidth efficiency, bandwidth attainability and THOS. Clustering is good for signal coordination in that either 2 clusters or 3 clusters will result in better performance measures that no partition. However, clustering is not always good for signal coordination in certain conditions. Though bandwidth and bandwidth efficiency of each sub-system can be improved after partition, control delay or number of stops for the corridor might be increased instead for certain conditions of the entire corridor. Whether or not clustering method can be used to partition a signalized system for the purpose of better signal coordination depends on specific traffic and geometric conditions of the corridor. When bandwidth capacity is exceeded by demand, bandwidth optimization should better give way to delay-based optimization strategies.

Objective: The validity of the Walking Impairment Questionnaire (WIQ) as a clinical tool for use by clinicians in the conservative management of patients with peripheral arterial disease (PAD) has not been well established. The objective of this study was to determine the validity of the WIQ as a tool to identify high and low walking ability (performance) in patients with PAD. Methods: We conducted a cross-sectional study and enrolled 132 new and existing PAD patients who consecutively attended the vascular clinic at Kingston General Hospital between May 2010 and May 2011. Patients with an Ankle Brachial Index ≤0.9 were approached for study inclusion. Participants were excluded if they had (a) severe ischemia requiring intervention; (b) comorbid conditions that limited walking (angina, congestive heart failure, chronic obstructive pulmonary disease or severe arthritis); (c) wheel chair, cane or walker requirement; (d) non-compressible arteries; and/or (e) severe cognitive impairment. Walking performance was assessed with the Walking Impairment Questionnaire (surrogate measure) and a standardized graded treadmill test (gold standard measure). Other study variables were obtained via questionnaire (age, sex, comorbid conditions and smoking status) or direct measurement (weight, height, waist circumference). Results: 123 patients completed the treadmill test (70.7% males, mean age of 66.5 and mean ABI of 0.6 with range 0-0.9). The scores on the WIQ ranged from 0 to 100 and absolute claudication distance (ACD) ranged from 0.03 to 0.98 miles. All WIQ subscale and overall scores were positively and moderately associated with the ACD (r values 0.63 to 0.68, p<0.05). Based on the area under the curve of the receiver operating characteristics curve analysis, an overall WIQ score of 42.5 or less identified low performers (sensitivity 0.9, specificity 0.7, area under the curve 0.89) while a combined distance and stair score of 75.5 or more identified high performers (sensitivity 0.4, specificity 0.9, area under the curve 0.81). Conclusions: Based on these findings, the WIQ, an easily administered self-report questionnaire, and the cutoffs identified could be used to quantify and classify walking ability in PAD patients, making this a potentially useful tool for clinicians to manage PAD patients. / Thesis (Master, Community Health & Epidemiology) -- Queen's University, 2011-08-25 13:03:34.694

No description available.

The role of the cardiovascular system is is to deliver oxygen and nutrients via arteries to the tissues of the body and to remove their waste products through the venous system. Due to certain pathological processes, arteries can be damaged resulting in a reduction of well oxygenated nutrient rich blood delivered to the tissues. Chronic hypoperfusion to the brain has been related to Alzeimer„s disease (AD). AD primarily affects people over 55 years of age, with an average duration of 7-10 years, resulting in death. Currently there are 600 million people in the world aged 60 years and over. This figure is expected to double by 2025 and to reach 2 billions by 2050. Finding a cure for a neurodegenerative disease such as AD would herald a major breakthrough in medical care. Currently AD is being widely investigated, but in order to find a cure, the complete pathophysiology of AD needs to be understood. Physilogical modelling could play a significant role to further develop that understanding. The underlying cause for AD is debated although several genetic loci have been identified for AD. Scientists have also demonstrated a strong connection with cerebral hypoperfusion. This results in tissue oxygen and nutrition deprivation which is a possible causative factor in the development of AD. In this thesis a Simulation model (SM) has been built to produce an arterial tree which resembles a natureal arterial tree. The SM model is based on Schreiner et al´s Constrained Constructive Optimization (CCO) method. The SM model produces a binary tree by choosing a random point in a defined area, and connects it to an exising tree structure, each time forming a new bifurcation. This bifurcation is optimized using the target function total minimum volume of the tree. The main difference between the CCO and SM method is the handling of the constrained areas in which the binary trees are grown within. The CCO method inceases the constrained area each time a segment is added to the tree structure, resulting in rescaling of the total tree each time. The SM tree utilizes a unit circle for the tree to grow in and uses a scaling factor to retrieve the real values of the tree segments as needed. Two trees were produced using the SM method, containing 250 (T250) and 2000 (T2000) terminals respectively. The segment Radii and length of the T2000 terminal tree was extracted and reorganized to fit the data structure of a zero-dimensional model developed by Alzaidi. This model was used to produce pressure and flow rate results for the T2000 tree. The relative perfusion of the infiltrated area in the T2000 tree was also calculated. This thesis shows a close resemblance between the SM tree and a true arterial tree, both visually and geometrically. The morphometric distribution of radii and length showed a good correlation between the SM tree and previous experimental research. The real values of radii and length found in the T2000 SM tree were found to be of larger radii and shorter length compared to previously reported values in the literature. However the results from the T250 SM tree showed excellent correlation with previous experimental results. The physiological parameters of pressure changes in the SM T2000 tree strongly mimic known in vivo physiological parameters from the human circulation. The flow rate in the tree was larger than expected, but can easily be rectified by changing the initial parameters of the SM program. The perfusion distribution diagram demonstrates a well known in vivo occurrence known as watershed zones which has recently been shown to be strongly associated with pathophysiological changes found on autopsies of brains from Alzheimer‟s patients.

Several research studies indicate the increasing problem obesity has become over the past few decades (Andersen 1999:41; Fox, 1999:56-60; Kuczmarshi et al., 1994:205-212). Obesity, after cigarette smoke, is the leading cause of death in the USA and a combination of diet factors and physical inactivity (two primary contributors of obesity) leads to an average of 300,000 deaths per year (McGinnis & Foege, 1993:2207-2212). Previously little information was available on the effect of obesity on the peripheral vascularization, and even less about the effect of obesity on arterial compliance (Raison et al., 1998:299-303). Research indicated a decrease in arterial compliance with an increase in body weight (Kumaran et al., 2002:7; Sutton-Tyrrell et al., 2001:431; Tounian et al., 2001:1400-1404; Stepniakowski & Egan, 1995:R567) however, contradictory research where no association between obesity and arterial compliance was indicated, has also been found (Singhal et al., 2002:1920; Mangoni et al., 1995:986). Mackey et al. (2002:16) also found that an increased aortic stiffness is positively associated with lowered physical activity levels. A lifestyle consisting of moderate physical activity, has a positive effect on the health, lowering of chronic illness risks, the prevention of cardiovascular diseases and the improvement of quality of lie in overweight and obese patients (Adams et al., 2003542; Ferreira et al., 2003:1670-1678; Macera, 2003:123; Mclnnis, 200396; Kolden et al., 2002:447). Moderate aerobic exercise is also seen as a potential non-pharmaceutical therapeutic method to increase age associated decrease in arterial compliance in young, middle aged and older adults (Gates et al., 2003:2213; Havlik et al., 2003:156; Seals, 2003:68; Moreau et al., 2003:865; Joyner, 2000:1214; Cameron et al., 1999:653). The objective of this study was firstly to determine the correlation between obesity and vascular function in Caucasian women between the ages 19 and 56 and to determine which marker of obesity is the best predictor of a weakened vascular function (see article one). The second objective was to determine the correlation between physical activity, obesity and arterial compliance in Caucasian women between the ages 19 and 56 years (see article 2). A total of 115 Caucasian women were recruited to participate in this study. Anthropometric measurements and a comprehensive body composition profile was taken using the BOD POD. The Finometer apparatus was used to measure the arterial compliance and the sphygmomanometer to measure the subjects blood pressure. The subjects completed the Yale Physical Activity Survey questionnaire to determine their physical activity index. This study seems to indicate a positive relationship between arterial compliance and obesity which could be explained by the influence blood volume had in determining arterial compliance. A negative correlation was found between obesity and blood pressure where an increase in obesity caused an increase in both systolic and diastolic blood pressure. A positive correlation was found between physical activity and obesity. The higher the activity levels were in this study, the less obese the subjects tended to be. No correlation was found between physical activity and arterial compliance. A clear trend, even though no statistically significant differences, was found between physical activity and blood pressure. The more active the subjects were, the lower their blood pressure tended to be. / Thesis (M.Sc. (Human Movement Science))--North-West University, Potchefstroom Campus, 2005

Pulmonary arterial hypertension (PAH) is a lethal disease characterized by excessive proliferation of pulmonary vascular cells, such as endothelial cells (ECs). Hereditary (H) PAH is mainly caused by ―loss-of-function‖ mutations in the gene coding for the bone morphogenetic protein type II receptor (BMPR2). However, the mechanisms by which these mutations cause PAH remain unclear. The hypothesis of this thesis was that BMPR2 mutations produce an imbalance in EC protein expression and/or activity that is integrally related to the development of abnormalities in lung vascular function and structure in HPAH. Patient-specific blood-outgrowth endothelial cells (BOECs) expanded ex vivo from peripheral blood mononuclear cells from patients with HPAH and healthy subjects were used to examine the consequences of BMPR2 mutations on the BOEC protein expression profile as well as on their functionality. Functional analyses of the BOECs revealed that HPAH-derived BOECs are more susceptible to apoptosis and more proliferative compared with healthy controls. Protein isolates of BOECs from patients with HPAH and from healthy subjects were subjected to 2-D gel electrophoresis and stained for total proteins and phosphoproteins, and to a quantitative computerassisted analysis. Differentially regulated proteins were identified by mass spectrometry (LC-MS/MS). Of the 416 total proteins detected under basal conditions, 11 were significantly downregulated in HPAH-derived BOECs and 11, including the translationally controlled tumor protein (TCTP), were upregulated. TCTP has previously been shown to be involved in systemic arteriolar remodeling, inflammation and growth. Therefore, the potential role of TCTP in PAH was studied in vivo in the SU5416 rat model of severe angioproliferative PAH. Immunofluorescence staining revealed high expression of TCTP in arteriolar ECs of PAH lungs tightly localized to proliferating cells within occlusive intimal lesions; whereas, only minimal TCTP expression was seen in vascular ECs of normal lungs. Similarly, abundant TCTP immunostaining was also seen in human PAH lung sections, again associated with complex vascular lesions. In BOECs, TCTP was found to participate in cell growth and survival. These data suggest that TCTP could play an important role in PAH by mediating pro-survival and growth signaling in vascular cells, contributing to occlusive pulmonary vascular remodeling triggered by EC apoptosis.

No description available.

Delayed control of haemorrhage or blood loss has been recognised as a major contributor to preventable trauma deaths, but early detection of internal bleeding is difficult due to unreliability of heart rate (HR) and blood pressure (BP) as markers of volume status. This thesis explores a novel method of early blood loss detection using a noninvasive finger photoplethysmographic (PPG) pulse oximetry waveform that is normally utilised in pulse oximeters for estimating arterial oxygen saturation. Graded head-up tilt (n = 13) and blood donation (n = 43) in human volunteers were selected as experimental models of mild to moderate blood loss. From the tilt study, a novel method for automatically detecting left ventricular ejection time (LVET) from the finger PPG waveform has been developed and verified by comparison with the LVET measured from aortic flow velocity. PPG waveform derived LVET (LVETp) and pulse transit time (PTT) were strongly correlated with aortic LVET and pre-ejection period respectively (median r = 0.954 and 0.964) and with the decrease in central blood volume indicated by the sine of the tilt angle (median r = -0.985 and 0.938), outperforming R-R interval (RRI) and BP in detecting mild central hypovolaemia. In the blood donation study, progressive blood loss was characterised by falling LVETp and rising PTT (p < 0.01). A new way of identifying haemorrhagic phases by monitoring changes and trends in LVETp, PTT and RRI has been proposed based on the results from the two studies. The utility of frequency spectrum analysis of PPG waveform variability (PPGV) in characterising blood loss has also been examined. A new technique of PPGV analysis by computing the coherence-weighted cross-spectrum has been proposed. It has been shown that the spectral measures of finger PPGV exhibited significant changes (p < 0.01) with blood donation and were mildly correlated with systemic vascular resistance in intensive care unit patients (r from 0.53 to 0.59, p < 0.0001), therefore may be useful for identification of different haemorrhagic phases. In conclusion, this thesis has established finger PPG waveform as a potentially useful noninvasive tool for early detection of blood loss.

Made available in DSpace on 2013-08-07T19:04:52Z (GMT). No. of bitstreams: 1 000391276-Texto+Completo-0.pdf: 700554 bytes, checksum: 80e872f040f001d97404a660a8e322b8 (MD5) Previous issue date: 2007 / L-arginine is the precursor of nitric oxide - a potent endogenous vasodilator. This amino acid is transported via two membrane transport systems: y+ and y+L. Total L-arginine erythrocyte maximal capacity is increased in preeclampsia syndrome, especially in hypertensive patients with superimposed preeclampsia. The hypothesis of the present study is that erythrocyte L-arginine transport is associated with hypertension. The aim was to evaluate the activity of y+ and y+L erythrocyte membrane transport systems of L-arginine, in normotensive and hypertensive women, and women with and without the hypertensive disorders of pregnancy. Sample was composed by 137 women divided into followed groups: 39 with preeclampsia (PE), 8 with superimposed preeclampsia (SPE), 14 with gestational hypertension (GH), 10 with chronic hypertension (CH), 28 pregnant controls (CP), 20 non-pregnant hypertensive (HAS) and 18 non-pregnant normotensive women (N). L-arginine erythrocyte uptake was measured using 14C as a marker, and N-ethylmaleimide as y+ transport system inhibitor to obtain the function of two transport systems separately. The results were submitted to Michaelis-Menten equation to determine the maximal capacity of transport (Vmax) and half saturation constant (km). Results showed no alteration in total and y+L Vmax. The maximal capacity of transport via y+ system was lower in PE, GH and CP in comparision with normotensive non-pregnant. Half saturation constant (km) had no difference between groups. / A L-arginina é o aminoácido precursor da síntese de óxido nítrico - um potente vasodilatador endógeno. Este aminoácido é transportado através da membrana celular por dois sistemas de transporte: y+ e y+L. A capacidade máxima de transporte eritrocitário total da L-arginina está aumentada na síndrome de préeclâmpsia (SPE), especialmente em pacientes previamente hipertensas com PE. A hipótese do presente estudo é que o aumento do transporte de L-arginina possa estar associado à hipertensão. O objetivo foi avaliar a atividade dos transportadores da L-arginina – sistemas y+ e y+L - em eritrócitos de mulheres normotensas e hipertensas, gestantes controle e portadoras de distúrbios hipertensivos da gestação.A amostra foi composta por 137 mulheres divididas nos seguintes grupos: 39 com pré-eclâmpsia (PE), 8 com pré-eclâmpsia sobreposta à hipertensão crônica (PES), 14 com hipertensão gestacional (HG), 10 gestantes com hipertensão crônica (HC), 28 gestantes controle (GN), 20 mulheres não-gestantes hipertensas (NG/HAS) e 18 normotensas (NG/N). O influxo eritrocitário de L-arginina foi mensurado usando 14C como marcador e N-etilmaleimida como inibidor do sistema de transporte y+ para obter a função dos dois sistemas em separado. Os resultados foram submetidos à equação cinética de Michaelis-Menten para determinar a capacidade máxima de transporte (Vmax) e a constante de meiasaturação (km). Os resultados mostraram que não houve alteração no Vmax - do influxo total e do sistema y+L. Os grupos PE, HG e GN apresentam a capacidade máxima de transporte pelo sistema y+ menor que NG/N. A constante de meia saturação (km) não foi diferente entre os grupos.