The mechanical properties of biomedical materials were determined and discussed in this study. The extension and tensile tests for aorta and coronary artery were carried out using tensile testing machine. Based on incompressibility of biological soft tissue, the stress-stretch curves of arteries were obtained. This study proposed a nonlinear Ogden material model for the numerical simulation of coronary artery extension during stent implantation. The corresponding Ogden model parameters were derived by the obtained stress-stretch curves from tensile tests. For validation, the proposed nonlinear Ogden material model for coronary artery was applied to a Palmaz type stent implantation process. The simulated stent deformation was found to be reasonable. It had a good correlation with the measured results. The microindentation experiments were used to measure the mechanical properties of enamel and dentine of human teeth in this study. To reveal the relation between the experimental parameters and measured mechanical properties, Young¡¦s moduli were investigated by varying experimental parameters. The parameter of maximum indentation load significantly influences measured values. Young¡¦s modulus varies very slightly when 10 to 100 mN of maximum indentation load applied. Young¡¦s modulus is not sensitive to the parameters of portion of unloading data and teeth age. The combination of finite element analysis and curve-fitting method is proposed to determine the mechanical properties of thin film deposited on substrate. The mechanical properties of thin film, i.e. Young¡¦s modulus, yield strength and strain-hardening exponent, were extracted by applying an iterative curve-fitting scheme to the experimental and simulated force-indentation depth curves during the microindentation loading and unloading processes. The variation of mechanical properties of TiN thin films with thicknesses ranging from 0.2 to 1.4 £gm was extracted. The results presented the film thickness effect makes the Young¡¦s modulus of TiN thin films reduces with reducing film thickness, particularly at thicknesses less than 0.8 £gm. Therefore, it can be inferred that a film thickness of 0.8 £gm possibly represents the upper bound when employing macroscopic mechanics with bulk material properties.

Background: Kawasaki disease (KD) affects mainly children younger than five years of age, leading to coronary artery lesions, and even to life-threatening myocardial infarctions. Since 1976, Kawasaki disease has occurred among thousands of children in Taiwan. Evidence suggests that inflammation plays a key role in the pathogenesis of atherosclerosis. Significant determinants of high sensitivity C-reactive protein (hs-CRP), which is a sensitive indicator of inflammation, as well as white blood cell (WBC) count, and high-density lipoprotein cholesterol (HDLc) and coronary artery lesion were identified. The relationships between these factors¡¦ concentration and arterial lesion were likewise investigated and had reported. The aim of this study was to determine the serum levels of the hs-CRP, WBC count, and plasma HDLc levels in patients with later phase of KD. Methods and Materials: From July 2005 to June 2006, 97 children with Kawasaki disease at least 1 year after diagnosis were recruited in this study. These participated children had been diagnosed as KD and collected at the interval of 2001 to 2004. Diagnosis was based on the 1984 revised by the KD Research Committee in Japan. The participants were grouped into 45 patients with KD and coronary aneurysms (Group I), 52 patients with KD and normal coronary arteries (Group II), and 50 healthy age-matched children (Control Group III). Their WBC count, systemic and diastolic blood pressures, body mass index, age, sex, fasting total cholesterol concentrations, triglyceride, high-density lipoprotein cholesterol (HDLc), low-density lipoprotein cholesterol, serum hs-CRP levels, and coronary artery lesion by cardioechography were recorded and compared. The analytical differences between hs-CRP, WBC count, and plasma HDLc levels and the coronary artery events in KD were examined. Results: Serum hs-CRP levels of Group I patients (mean 0.264 mg/dl) was significantly greater than that of Group II (mean 0.155 mg/dl, p=0.006) and Group III patients (mean 0.116 mg/dl, p =0.017). Similarly, the WBC count of Group I patients (mean 6,543.11/mm3) was significantly greater than that of Group II (mean 5,720.19/mm3, p=0.029), and Group III patients (mean 5,611.27/mm3, p =0.012). However, plasma HDLc levels of Group I patients (mean 41.42 mg/dl) was significantly lesser than that of Group II (mean 44.79 mg/dl, p=0.035), and Control Group III patients (mean 46.58 mg/dl, p=0.027). There was a positive association between hs-CRP and WBC count levels (r = 0.641, p < 0.05), but none between hs-CRP and plasma HDLc levels. Conclusions: There is the possibility of ongoing low-grade inflammation late after the convalescent phase of Kawasaki disease in children with coronary aneurysms, which may have a role in increasing coronary artery dysfunction. These results also suggest that hs-CRP, WBC count, and plasma HDLc levels are useful parameters for predicting formation of coronary artery lesion even in children after onset of KD.

In finite elasticity, while developing representation for stress, it is customary to require the reference configuration to be stress free. This study relaxes this requirement and develops representations for stress from a stressed reference configuration. Using the fact that the value of Cauchy stress in the current configuration is independent of the choice of the reference configuration, even though the formula used to compute it depends on the choice of the reference configuration, the sought representation is obtained. It is then assumed that there exists a piecewise smooth mapping between a configuration with prestresses and a configuration that is stress free, and the representation obtained above is used to study the mechanical response of prestressed bodies. The prestress fields are obtained by directly integrating the balance of linear momentum along with the traction free boundary condition. Then, different classes of boundary value problems for the type of inhomogeneous and prestressed bodies of interest are formulated and studied. For the cases studied, it is found that even the global measures like axial-load required to engender a given stretch ratio for a prestressed body vary from the homogeneous stress free bodies, though not significantly. The local measures - stress and deformation - in a prestressed body differ considerably from their homogeneous stress free counterparts. The above gained knowledge is applied to understand the mechanics of circumflex arteries obtained from normotensive and hypertensive micro-mini pigs. It is found that the deformation of these arteries when subjected to inflation and axial extension is not of the form r = r(R), µ = £, z = Z. Comparison is also made between the response of an artery at various levels of smooth muscle activation and stretch ratio as well as normotensive and hypertensive specimens, using statistical methods.

Hypertension is a risk factor for many cardiovascular and cerebrovascular diseases such as atherosclerosis and stroke. It is therefore important to understand the effect of hypertension on temporal growth and remodeling of arteries. In this study, experimental hypertension was induced in the mini-pig by aortic coarctation. Basilar arteries and aortas were collected for analysis over an eight week period of hypertension with specimens from normotensive animals serving as controls. Changes in mechanical properties of the basilar artery were evaluated by in vitro pressure-diameter tests on intact cylindrical segments at their in situ length. The basilar arteries from hypertensive animals became less distensible, reflecting increases in both structural and material stiffness, compared to their normotensive counterparts. The circumferential stress rapidly returned toward its homeostatic value by increasing the wall thickness within two weeks. Immunohistochemistry, which is capable of illustrating the localization and distribution of protein expression, was performed to examine changes in wall constituents in the aorta. The increased medial thickness observed in hypertensive pigs compared to normotensive pigs was due to hyperplasia of smooth muscle cells (SMCs) and accumulation of extracellular matrix proteins, which were accompanied by the phenotypic modulation of SMCs. The increased interlamellar thickness, collagen fibers, and the thickness of elastic lamina found in the inner media of hypertensive animal may be associated with the gradient of stress decreasing into the outer media. SMC proliferation, if any, was found evenly distributed across the media, however. In cases showing increased proliferation and matrix protein synthesis, the SMC contractile markers were down-regulated whereas the SMC synthetic markers were up-regulated. While the aortic intima appeared normal in the normotensive animals, neointima formation, which may predispose the vessel to atheroma formation, was found in the hypertensive animals. Immunohistochemistry of Hsp47 and procollagen revealed that the endothelial cells (ECs) may produce collagen, specifically type I collagen in response to hypertension and contribute to the thickened intima. In addition, lectin staining for ECs markers and immunostaining for eNOS suggested that endothelial cells may transdifferentiate into intimal SMCs. These findings suggested an alternative role that ECs may play in hypertension-induced atherogenesis.

Research Objective Patients with chronic kidney disease (CKD) are at increased risk for atherosclerosis and peripheral artery disease (PAD). PAD has received far less attention than coronary artery disease (CAD) in CKD patients. Few studies have examined risk factors for PAD in CKD. We studied the possible related risk factors and benefit of hypertension treatment in CKD patients with PAD. Data Sources We included 129 patients of both sexes with stages 3 to 5 of CKD, as described by the Kidney Outcome Quality Initiatives (K/DOQI ) classification, without receiving dialysis therapy, not previously diagnosed with PAD. Study Design The following information were collected within six month period, including demographic characteristics, history of hypertension, anti-hypertension drug, diabetes, smoking, and pre-existing cardiovascular disease, body mass index (BMI), fasting blood glucose, HbA1c, total cholesterol, triglyceride(TG), high density lipoprotein cholesterol (HDL), low density lipoprotein cholesterol(LDL), calcium (Ca), phosphate(P), Albumin, uric acid, urine protein. Ankle-brachial index (ABI) is a noninvasive diagnostic test that is efficient in detecting asymptomatic PAD with ABI <0.9. Findings There were 22 (17.7 %) participants with PAD. Higher systolic blood pressure (SBP), higher diastolic blood pressure (DBP), higher pulse pressure showed strong association with PAD in CKD patients. On further analysis, significant fewer patients treated with calcium channel blocker (CCB) in hypertensive CKD patients with PAD (£q2 =7.055, p =0.008). The multivariate logistic regression analysis in hypertensive patients demonstrated the risk factors for PAD was pulse pressure, and Calcium channel blocker treatment may correlate with decreasing PAD formation (odds ratio= 0.232, 95% CI=0.07-0.73, p =0.013) in CKD patients. Conclusion There is a high prevalence rate of PAD in population of CKD, especially those with hypertension. ABI should be routinely examined in these patients who can benefit earlier from therapeutic measures.

Detection of coronary calcification from computed tomography scans is a noninvasive examination and has great potential for heart disease diagnosis. This study proposes new features to characterize calcium lesions. Different from the traditional calcium score features, these features are generated from the texture, shape, and gray level statistics of the calcium lesions. We study the correlation between these features and acute myocardial infarction and then compare the results with traditional calcium score features. According to the location of the lesions, patients are first divided into two groups. In one group, the myocardial infarction is located in segment of culprit lesion. For the second group, myocardial infarction is located in segment of non-culprit lesion. In comparing their means, the corresponding p-value of gray level statistics feature ¡§histogram relative smoothness¡¨ could reach 4.47E-07, which has fairly high significance. Furthermore, in studying the differences among patients, experiment on Hypercholesterolemia provide a good result. By comparing the means of patients which are classified into Hypercholesterolemia and non-Hypercholesterolemia groups, the corresponding p-value of texture feature ¡§inverse difference moment¡¨ could reach 3.74E-04. Initially, acute myocardial infarction do not have statistically significant result However, after adding the location weighting factor for the lesions, the corresponding p-value of texture feature ¡§average of information measures of correlation¡¨ could be reduced to 8.8921E-03, and p-value of gray level statistics feature ¡§Histogram relative Smoothness¡¨ could be improved to 2.4019E-02.

Numerous studies in North America, Europe and Australia have linked depression to increased risk of morbidity and mortality in coronary artery disease (CAD). Although the co-morbidity of depression and CAD is well documented in the western world, little work on the subject has been carried out in Asia. Differing depression presentations in Asia necessitate the use of culture-specific depression rating scales. This study sought to determine whether the correlation between CAD and depression documented in western countries also exists in an Asian nation: Thailand. It was hypothesized that rates of depressive symptoms were higher in Thai inpatients with either unstable angina or recent myocardial infarction than in Thai inpatients with non-cardiac (orthopedic) complications. A 15-question culturally-appropriate self-rating depression inventory was administered to 56 Thai inpatients33 cardiac and 23 orthopedicat two public and one private hospital in Bangkok. Subjects were asked to rate each of the fifteen items on a scale from 0-3 based on how they felt during the past week. Higher scores correlated with greater depressive symptoms. Five cardiac and two orthopedic patients were excluded from the final analysis because of past medical history of major depressive disorder. Of the remaining 49 patients, questionnaire scores ranged from 1 to 23, with a mean depression score of 9.00 (S.E.M.=.84). Cardiac patients showed significantly greater depressive symptoms than their orthopedic counterparts at one public and one private hospital: Ramathibodi Hospital (P=.01) and Bangkok General Hospital (P=.005), respectively. For cardiology patients, the three highest scoring items were early insomnia (Mean = 1.39), late insomnia (Mean = 1.25) and loss of appetite (Mean = 1.04). For orthopedic patients, the three highest scoring items were work inhibition (Mean = 1.05), anxiety (Mean = .86), and early insomnia (Mean = .86). On post-hoc analysis, it was shown that patients in hospital units with air-conditioning showed significantly fewer depressive symptoms than patients without air-conditioning (P=.003), where the daily temperature often reached 115[degrees]F. Rates of depressive symptoms did not differ in accordance with education level (P=.15), gender (P=.49) or age (P=.29). In conclusion, this study provides some evidence that Thai inpatients hospitalized for severe CAD have greater depressive experience than their orthopedic counterparts. This finding supports our hypothesis that depression and CAD are linked in Thailand as they are in western countries.

Thesis (Ph. D.)--West Virginia University, 2009. / Title from document title page. Document formatted into pages; contains x, 121 p. : ill. (some col.). Vita. Includes abstract. Includes bibliographical references (p. 84-118).

Σκοπός της πρόδρομης αυτής τυχαιοποιημένης μελέτης ήταν να εκτιμήσουμε την αποτελεσματικότητα της εξωτερικής ακτινοβόλησης και την προφυλακτική της δράση στην μείωση της επαναστένωσης του αυλού της επιπολής μηριαίας αρτηρίας μετά από αγγειοπλαστική και τοποθέτηση μεταλλικής ενδοπρόθεσης (stent). Στην μελέτη συμπεριελήφθησαν ασθενείς με σοβαρού βαθμού στένωση ή απόφραξη της επιπολής μηριαίας αρτηρίας, οι οποίοι υποβλήθηκαν σε διαδερμική αγγειοπλαστική με μπαλόνι και τοποθέτηση stent για την αποκατάσταση του προβλήματός τους, και τυχαιοποιήθηκαν σε δυο ομάδες. Οι ασθενείς της πρώτης ομάδας υποβλήθηκαν σε αγγειοπλαστική με μπαλόνι και τοποθέτηση stent στην περιοχή της στένωσης ή της απόφραξης χωρίς να υποβληθούν σε εξωτερική ακτινοβόληση της περιοχής. Οι ασθενείς της δεύτερης ομάδας, 24 ώρες μετά την αγγειοπλαστική με μπαλόνι και τοποθέτηση stent στην περιοχή της στένωσης ή της απόφραξης, υποβλήθηκαν σε εξωτερική ακτινοβόληση στην περιοχή, με συνολικά χορηγούμενη δόση 24Gy που δόθηκαν σε 6 συνεδρίες ανά 48 ώρες. Μετά το τέλος της ακτινοβόλησης οι ασθενείς παρακολουθούνταν ανά τακτά χρονικά διαστήματα. Η συνολική διάρκεια παρακολούθησης ήταν 1 έτος, με τελικό σημείο αξιολόγησης το 1 έτος. / Purpose: To evaluate the long-term results of external beam irradiation (EBI), for the prevention of neointimal hyperplasia, after percutaneous transluminal angioplasty (PTA) and stenting of the superficial femoral artery. Materials and methods: A prospective randomised study was conducted from November 2000 to February 2002. A total of 60 patients who suffered from superficial femoral artery stenoses or short occlusions included in this study. Following successful post-angioplasty stenting, patients were randomly assigned in two groups and thirty of them received external beam irradiation (6 MV photons, total dose of 24 Gy in 6 fractions,during a 2 week period) at the stented area (EBI group) while the rest thirty received no radiation therapy (Control group).All patients were advised to receive anti-platelet therapy. Results and conclusions: Radiation therapy was technically feasible in all patients, without radiation related side effects. Statistically significant differences (p<0,05) observed at the 1- year follow-up concerning the primary patency (66% for the irradiated patients vs 33% for the control patients) and re-intervention rates (40% for the irradiated patients vs 70% for the control patients) between the two groups. Irradiated patients revealed re-stenotic lesions mainly at the stent ends, while control group patients suffered extensive re-stenotic lesions within the stent lumen and the stent ends.Our study suggests that EBI is feasible, safe and effective method for the prevention of neointimal hyperplasia at the superficial femoral artery. Further studies are deemed necessary to optimize the radiation dose and the number of fractions.

The purpose of this study was to investigate the presence of arterial insufficiency in patients undergoing CABG surgery and whether arterial insufficiency is a risk factor for postoperative wound infections in the harvesting leg. Patients who had CABG surgery were enrolled consecutively. A total of 144 patients participated in the study. During their hospital stay demographic data was recorded, as well as pre-, intra-, and postoperative tests and risk factors. The patients answered a questionnaire regarding postoperative wound infections 30 days after surgery patients answered a questionnaire regarding infections. The known and potential risk factors that were recorded were BMI, HB, tobacco usage, diagnosed diabetes, hyperglycemia, duration of surgery, the lowest temperature during surgery and clinical or subclinical arterial insufficiency. The result showed that 34% had postoperative wound infections in the harvesting leg and 26 patients had an ABI (Ankel Brachial Index) indicating arterial insufficiency. There was no significant relationship between ABI and postoperative wound infections in the lower extremity in the total study group (p = 0.36) nor among men (p = 0.92). There was a significant correlation between ABI and postoperative wound infections in the lower extremity (p = 0.02) among women. The conclusion is that arterial insufficiency is more prevalent in women. The relationship between postoperative infections of the lower limbs and arterial insufficiency was significant for the participating women, but not in the total group nor among the men.