No description available.

The genes coding for apolipoproteins B and A-I (apoB and apoA-I) are potential candidate loci for studying heritable determinants of lipid levels, a primary risk factor for development of atherosclerotic vascular disease. A preliminary step in genetic epidemiological analysis is the detection of common genetic variants of a candidate gene for use in subsequent population association studies. This study set out to develop techniques to identify common genetic variants at both the apoB and apoA-I loci. The apoB gene was investigated at the protein level by high resolution electrophoretic techniques, in particular isoelectric focusing (IEF). Although an apparently successful technique was developed producing highly resolved bands, evidence is presented demonstrating that the banding pattern possibly represents artefact resulting from an interaction of apoB with components of the IEF system. Despite exhaustive investigation into possible means of overcoming this problem, including cleavage of apoB by thrombin into smaller fragments, it was concluded that the application of IEF to apoB is not practicable as a means of detecting genetically derived variants suitable for subsequent association studies. The apoA-I gene was investigated at the DNA level by the Polymerase Chain Reaction (PCR) followed by direct sequencing. This technique has yielded three variants in the 5' end of the gene; i) A G to A transition at -75 (GA-75AI) from the initiation of transcription, ii) a C to T transition at &'43 83 (CT&'43 83AI) and iii) a second G to A at &'43 84 (GA&'43 84AI). The frequency of each of these polymorphisms was determined in five populations. Firstly, the 'Glasgow' population, comprising 89 males and 98 females for which a previously compiled data base of lipoprotein and life-style variables was available. This population was used to determine the effects of genotype on lipoprotein parameters separately for males and females. The four other populations comprised a case/control study whereby the frequency of each polymorphism was compared between a healthy control population from Aberdeen and three diseased populations, a) Aberdeen female myocardial infarction survivors (AMI) consisting of 69 individuals, b) Aberdeen dyslipidaemic Hypertensives (ADH) consisting of 25 males and 17 females c) Aberdeen hyperlipidaemia(AH) consisting of 29 males and 29 females.

No description available.

Increased platelet activation and inflammation play a key role in atherothrombosis. Patients with peripheral arterial disease are at increased risk of adverse cardiovascular events, particularly at the time of surgery. We postulated that the increase in peri-operative cardiovascular events is mediated by increased platelet activation and inflammation. We hypothesized that peri-operative dual anti-platelet therapy would improve biomarkers of atherothrombosis without causing unacceptable bleeding in patients undergoing surgery for critical limb ischaemia (CLI). Prior to interventional study, I validated a sensitive flow cytometric technique for the reproducible assessment of in vivo platelet activation in patients with peripheral arterial disease. Thirty patients with stable claudication, attended on two occasions to permit within-day and between-day comparisons. A variety of platelet activation markers were compared to the gold standard of platelet–monocyte aggregation. Platelet-monocyte aggregation demonstrated comparable within-day (mean difference ± co-efficient of reproducibility; 0.9±15.4%) and between-day reproducibility (2.0±12.4%). Plateletmonocyte aggregates correlated well with other platelet activation markers (P selectin r=0.30; Platelet CD40L r=0.41; Platelet microparticles r=0.27; P≤0.026) and monocyte activation markers (monocyte CD40 r=0.27;monocyte CD11b r=0.47; P≤0.026). In a cross sectional study, I demonstrated that resting in vivo platelet activation and inflammation was increased in patients with CLI in comparison to healthy controls, patients with stable claudication and those undergoing treatment for acute coronary syndromes. In addition, platelet activation and inflammation throughout the peri-operative period was markedly increased in CLI patients compared with non-vascular patients undergoing arthroplasty, and exceeded the rise attributable to the stress of surgery itself. In a prospective double-blind randomised controlled trial, 108 patients undergoing infra-inguinal revascularisation or amputation for CLI were maintained on aspirin (75 mg daily) and randomised to clopidogrel (600 mg prior to surgery, and 75 mg daily for 3 days; n=50) or matched placebo (n=58). Peri-operative in vivo platelet activation and inflammation, cardiac-Troponin I (c-TnI) release and bleeding outcomes were recorded. Clopidogrel reduced markers of platelet activation and inflammation before surgery and throughout the post-operative period. Overall, there were 18 troponin-positive events (16.7%), with half of the troponin rises (9) occurring prior to surgery. Patients with postoperative elevations in c-Tn I had significantly greater levels of pre-operative platelet-monocyte aggregation, monocyte CD40, IL-6 and hsCRP. However, despite reducing platelet and inflammatory markers, clopidogrel did not have a direct effect on peri-operative c-Tn I. There was no increase in major life-threatening or minor bleeding, although blood transfusions and wound haematomas were significantly increased. Using sensitive and validated methodologies, I have provided a detailed examination of in vivo platelet activation and inflammation in high-risk vascular surgical patients. This approach has provided the first objective assessment of the risks and benefits of intensive peri-operative anti-platelet therapy in this patient group. Dual anti-platelet therapy reduced biomarkers of atherothrombosis without causing unacceptable bleeding. However, large-scale clinical trials would be required to confirm whether these reductions translate into improvements in clinical outcome.

Peripheral arterial disease (PAD) defines atherosclerotic disease of the arteries to the legs. PAD begins early in life and remains asymptomatic over long periods. The ankle brachial index (ABI) is an important diagnostic test which can identify asymptomatic individuals and serve as a good marker of the underlying peripheral and systemic atherosclerosis. Recent advances in vascular biology proposed a role of inflammatory and haemostatic mechanisms in atherosclerotic disease. Although inflammatory and haemostatic markers have been associated with coronary atherosclerosis in large scale epidemiological studies their role in PAD development is not well established and for many markers unknown. Also, their relationship with the progression of early asymptomatic disease has not been studied before. The aim of this thesis was to examine 12 markers of inflammation and haemostasis in relation to peripheral atherosclerotic progression and incident PAD. The Edinburgh Artery Study was used for this analysis. This is a population based cohort study of 1,592 men and women recruited in 1987. ABI was measured at baseline and at two follow up examinations which were conducted after 5 and after 12 years. Also, subjects were followed up for cardiovascular events for 17 years. Conventional cardiovascular risk factors, C-reactive protein (CRP), interleukin-6 (IL-6), intercellular adhesion molecule 1 (ICAM-1), vascular adhesion molecule-1 (VCAM-1), E-selectin, fibrinogen, D-dimer, tissue plasminogen activator (t-PA), vonWillebrand factor (vWF), factor VII, fibrinopeptide A (FpA) and prothrombin fragments 1+2 (F1+2) were measured at baseline. Valid ABI measurements were available for 1,582 subjects at baseline, for 1,081 subjects at the 5 year follow up and for 816 subjects at the 12 year follow up. The population showed a progression in atherosclerotic disease assessed by the mean ABI decline over time. The mean change in ABI was -0.04 (0.18) after 5 years and -0.06 (0.19) after 12 years. From inflammatory markers, CRP (p <0.01), IL-6 (p <0.001) and ICAM-1 (p <0.01) were associated with atherosclerotic progression after 12 years, independently of baseline ABI and of conventional cardiovascular risk factors. Also, from haemostatic markers, fibrinogen (p =0.05) and D-dimer (p ≤ 0.05) were significantly associated with atherosclerotic progression independently of baseline ABI and cardiovascular risk factors. Moreover, subjects with higher levels of both D-dimer and IL-6 at baseline had the greatest ABI decline. Also, IL-6 showed the stronger independent effect on atherosclerotic progression and retained statistical significance after adjustments for all inflammatory markers and for fibrinogen and D-dimer. Approximately 26% of the baseline population developed at least one event of major CVD and 14% of the baseline population developed symptomatic PAD after 17 years of follow up. Inflammatory markers, CRP and IL-6 showed modest associations with PAD which lost statistical significance in the multivariable model. On the other hand, these markers were associated with incident major CVD with hazard ratios (95% CI) 1.6 (1.2, 2.3) and 1.8 (1.3, 2.6) respectively (top vs. bottom tertile) in the multivariable model. ICAM-1 showed weak associations with incident CVD, however, was significantly associated with PAD with hazard ratio (95% CI) 1.8 (1.2, 2.7) (top vs. bottom tertile) after adjustments for cardiovascular risk factors and CVD at baseline. Haemostatic markers, fibrinogen and D-dimer were associated with 2.2 (95% CI: 1.5, 3.2) and 1.7 (1.2, 2.6) increase in the risk of PAD development and 1.8 (1.3, 2.3) and 1.6 (1.2, 2.1) increase in the risk of CVD independently of cardiovascular risk factors and history of CVD at baseline, respectively. This analysis showed a major role of inflammatory markers, CRP, IL-6 and ICAM-1 in atherosclerotic development and progression. In addition, fibrinogen and D-dimer, but not other haemostatic factors, were associated with progressive and incident peripheral atherosclerosis. Since D-dimer and fibrinogen are acute phase reactants, these data support the hypothesis that inflammation is more related to atherosclerosis than is hypercoagulation. Most importantly, the majority of the reported associations were not explained by increased levels of cardiovascular risk factors or pre-existing clinical or subclinical arterial disease. Thus these markers are more likely to have a causal than a consequential role in atherosclerotic disease.

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

Indiana University-Purdue University Indianapolis (IUPUI) / Objective: Gold standard therapy for chronic limb threatening ischemia (CLTI) is revascularization but in patients in whom below-the-knee bypass is indicated autologous vein conduit may not be available. Contemporary outcomes of distal bypass with suboptimal conduits have not been well described and recent advances in non-surgical therapies raise the question of whether in some cases there is evidence that these should be considered. Methods: Data was obtained from the Vascular Quality Initiative (VQI) registry as well as from a multi-center, randomized clinical trial of cell therapy. Incidence of major amputation after distal bypass was estimated for the VQI cohort by conduit type using non-parametric survival analysis with death as a competing risk. A cox proportional hazards model was then fit to the pooled data in a stepwise fashion with death as a competing risk, including evaluations for appropriate transformation, time dependency and interactions for each included covariate, and hazard ratios were estimated for the risk of major amputation by treatment. Results: At 365 days, the estimated cumulative incidence of major amputation with death as a competing risk is 25% after distal bypass with non-autologous biologic conduit (0.2499, 95% CI 0.2242 - 0.2785), 13% for prosthetic (0.1276, 95% CI 0.1172 - 0.1389) and 9% for GSV (0.0900, 95% CI 0.0848 - 0.0956). The cox proportional hazards model found a significant interaction between age and treatment. Compared to bypass with non-autogenous biologic, the hazard ratios for bypass with GSV were 0.41 (p<0.0001), 0.41 (p<0.0001), 0.42 (p<0.0001) and 0.42 (p<0.0001) respectively at ages 55, 60, 65 and 70 and for bypass with prosthetic were 0.68 (p=0.0043), 0.67 (p=0.0004), 0.65 (p<0.0001) and 0.64 (p<0.0001) respectively and for autologous cell therapy 0.22 (p=0.0005), 0.34 (p=0.0011), 0.52 (p=0.0196) and 0.76 (p=0.3677) respectively. No significant differences were found between best medical management and distal bypass with non-autologous biologic. Conclusion: The risk of major amputation after distal bypass is lowest in patients with GSV conduit and highest following bypass with non-autologous biologic. Using a semi-parametric model, cell therapy was estimated to significantly decrease the risk of amputation compared to distal bypass with non-autologous biologic conduit in younger patients.

Patients with peripheral arterial disease (PAD) can only walk so far before they get leg pain (intermittent claudication) and have to stop. They are also at risk in the future of needing amputation of one of their limbs. Allopurinol is a new possible treatment for this condition as it has been shown in coronary arterial disease to prolong exercise before angina pain occurs. This is thought to be because allopurinol can both prevent oxygen wastage in tissues and prevent the formation of harmful oxidative stress. We hypothesised that allopurinol could prolong the time to leg pain in participants with PAD. In a double-blind, randomised controlled clinical trial 50 participants with PAD were randomised to receive either allopurinol 300mg twice daily or placebo for six months. The primary outcome was change in exercise capacity on treadmill testing at six months. Secondary outcomes were six-minute walking distance, Walking Impairment Questionnaire, SF-36 QoL questionnaire, flow-mediated dilatation and oxidised LDL. Outcome measures were repeated mid-study and at end of study. The mean age of participants was 68.4 years (SD 1.2) with 39/50 (78%) male. Only five participants withdrew in the course of the study, two in the active group and three in the placebo group. There was a significant reduction in uric acid levels in those on active treatment of 52.1% (p<0.001), but no significant change in either the pain-free or the maximum distance they were able to walk. Other measures of exercise capacity, blood vessel function and the participants’ own assessment of their health and walking ability also did not change during the course of the study. In summary, although allopurinol has been shown to be of benefit in a number of other diseases, in this study there was no evidence of any improvement following treatment in patients with peripheral arterial disease.

Photoplethysmography (PPG) has become widely accepted as a valuable clinical tool for performing non-invasive biomedical monitoring. The dominant clinical application of PPG has been pulse oximetry, which uses spectral analysis of the peripheral blood supply to establish haemoglobin saturation. PPG has also found success in screening for venous dysfunction, though to a limited degree. Arterial Disease (AD) is a condition where blood flow in the arteries of the body is reduced,a condition known as ischaernia. Ischaernia can result in pain in the affected areas, such as chest pain for an ischearnic heart, but does not always produce symptoms. The most common form of AD is arteriosclerosis, which affects around 5% of the population over 50 years old. Arteriosclerosis, more commonly known as 'hardening of the arteries' is a condition that results in a gradual thickening, hardening and loss of elasticity in the walls of the arteries, reducing overall blood flow. This thesis investigates the possibility of employing PPG to perform vascular assessment, specifically arterial assessment, in two ways. PPG based perfusion monitoring may allow identification of ischaernia in the periphery. To further investigate this premise, prospective experimental trials are performed, firstly to assess the viability of PPG based perfusion monitoring and culminating in the development of a more objective method for determining ABPI using PPG based vascular assessment. A complex interaction between the heart and the connective vasculature, detected at the measuring site, generates the PPG signal. The haemodynamic properties of the vasculature will affect the shape of the PPG waveform, characterising the PPG signal with the properties of the intermediary vasculature. This thesis investigates the feasibility of deriving quantitative vascular parameters from the PPG signal. A quantitative approach allows direct identification of pathology, simplifying vascular assessment. Both forward and inverse models are developed in order to investigate this topic. Application of the models in prospective experimental trials with both normal subjects and subjects suffering PVD have shown encouraging results. It is concluded that the PPG signal contains information on the connective vasculature of the subject. PPG may be used to perform vascular assessment using either perfusion based techniques, where the magnitude of the PPG signal is of interest, or by directly assessing the connective vasculature using PPG, where the shape of the PPG signal is of interest. it is argued that PPG perfusion based techniques for performing the ABPI diagnosis protocol can offer greater sensitivity to the onset of PAD, compared to more conventional methods. It is speculated that the PPG based ABPI diagnosis protocol could provide enhanced PAD diagnosis, detecting the onset of the disease and allowing a treatmenpt lan to be formed soonert han was possible previously. The determination of quantitative vascular parameters using PPG shape could allow direct vascular diagnosis, reducing subjectivity due to interpretation. The prospective trials investigating PPG shape analysis concentrated on PVD diagnosis, but it is speculated that quantitative PPG shaped based vascular assessment could be a powerful tool in the diagnosis of many vascular based pathological conditions.

Made available in DSpace on 2014-06-11T19:23:06Z (GMT). No. of bitstreams: 0 Previous issue date: 2011-10-04Bitstream added on 2014-06-13T18:50:20Z : No. of bitstreams: 1 bertanha_m_me_botfm.pdf: 4042528 bytes, checksum: cdc59622a6658e29d1187a28f3ccdba1 (MD5) / Ministério da Saúde / O cultivo de células tronco (CT) e a descoberta de técnicas que promovem a diferenciação tecidual apontam para novos domínios da medicina: a terapia celular e a engenharia de tecidos (ET). As limitações da medicina atual encontram na ET uma nova possibilidade terapêutica, com tratamentos regenerativos ou substitutivos para os tecidos danificados. Dentre as limitações médicas encontram-se as doenças arteriais obstrutivas periféricas (DAOP). A DAOP está presente em 5% da população e cerca de 20 a 30% dos casos podem evoluir para amputação do membro inferior acometido, mesmo com os tratamentos hoje existentes. A ET apresenta-se como uma ferramenta promissora para a resolução dos problemas cardiovasculares, particularmente para os que afetam as artérias de pequeno diâmetro (<5 mm), sendo factível a produção de enxertos vasculares autólogos, sob a ótica da medicina personalizada. O objetivo deste trabalho foi construir de um modelo experimental de vaso sanguíneo para enxerto, utilizando técnicas de ET para a diferenciação de células tronco mesenquimais de tecido adiposo (CTMta) em células endoteliais. Inúmeras etapas metodológicas foram necessárias: identificação da melhor forma de descelularizar as veias de animais doadores para confecção do arcabouço (scaffold), onde foram comparados 3 diferentes protocolos utilizando os detergentes Triton X-100, deoxicolato de sódio (DS) e dodecil sulfato de sódio (SDS); obtenção, expansão e caracterização por citometria de fluxo com anti-CD90 de CTMta; comprovação da adesão das CTMta sobre o scaffold utilizando imunofluorescência e o kit Qtracker; estabelecimento do índice de apoptose das CTMta sobre o scaffold descelularizado por eventual resíduo químico; análise histológica por HE e realização de imunohistoquímica com... / Stem cells (SC) cultivation and the development of new techniques to promote tissue differentiation evolved to new medicine fields of research: cell therapy and tissue engineering (TE). The current limitations in medicine rely on TE for new therapies as they provide regeneration and substitution of the damaged tissue. Within therapeutic limitations are the peripheral arterial obstruction diseases (PAD). PAD affects 5% of population and about 20-30% of cases may progress to amputation of the limb, even if the treatments that exist today. TE is a promising tool for cardiovascular diseases, especially those where the vessel is a small caliber artery (<5 mm), as it is possible to recreate the structure of the vessel with autologous vascular grafts from the perspective of personalized medicine. This research aimed to propose the creation of an experimental blood vessel using TE techniques and adipose-derived stem cell differentiation into endothelium. Several techniques were required: to gather enough veins and remove its cells, using three different protocols with Triton X 100, sodium deoxycholate (SD) and sodium dodecil sulfate (SDS); to obtain, cultivate and characterize adipose-derived stem cells with the CD90 marker and flow citometry; to prove the cells could adhere to the scaffold using immunofluorescence and Qtracker kit; to establish the cell apoptosis on the scaffold for possible chemical residue; histology and immunohistochemistry on the cell seeded scaffold using the fascin marker. Were obtained 90 jugular and cava vein segments and were decellularized, withing 11 different protocols. The best protocols were 2h of 1% SD, 1h of 2% SDS and 2h of 1% SDS. The protocols where triton were used gave no good results. There was no relevant difference between the apoptosis on the best... (Complete abstract click electronic access below)