Atherosclerotic carotid plaque assessment with multidetector computed tomography angiography

This thesis evaluates the role of MDCT angiography in 1) the depiction of atherosclerotic disease and subsequent luminal stenosis in the arteries that supplies the brain with blood, and 2) the assessment of atherosclerotic plaque features that have been related to plaque vulnerability. The studies can be subdivided in three main categories: 1) optimization of data acquisition protocol, 2) validation studies, including assessment of the accuracy of MDCTA in comparison to histology and interobserver studies, and 3) clinical cross-sectional studies. From the first part of this thesis we can conclude that an optimal protocol for MDCT angiography of the supra-aortic arteries incorporates the use of 80 ml contrast material and a 40 ml saline bolus chaser, a craniocaudal scan direction, and in respect to atherosclerotic carotid plaque imaging a tube current of 120 kVp and an intermediate reconstruction algorithm. The second part of this thesis allows to conclude that MDCTA is capable of characterizing and quantifying plaque and plaque component areas in good correlation with histology. However, lipid core can only be adequately quantified in mildly calcified plaques, and in vivo assessment of atherosclerotic plaque and plaque component volumes is feasible with a moderate reproducibility. In addition we can conclude that, with MDCT angiography, intracranial carotid artery calcifications can reproducibly be quantified and that carotid plaque surface morphology can be assessed with a high reproducibility. In the third part of this thesis we evaluated the characteristics of possible MDCTA-assessed plaque parameters (the volume of intracranial calcifications, carotid plaque morphology, and carotid plaque volume and plaque component volumes). Associations were found with several cardiovascular risk factors. Some plaque parameters were related to the presence and type of cerebrovascular symptomatology. We conclude that atherosclerotic plaque parameters can be imaged adequately with MDCTA. These parameters seem to have a possible additional value, besides the degree of stenosis, as a marker of atherosclerotic disease and as predictor of (recurrent) ischemic cerebrovascular events

Assessment of atherosclerotic carotid plaque volume with multidetector computed tomography angiography

Purpose The amount of atherosclerotic plaque and its components (calcifications, fibrous tissue, and lipid core) could be better predictors of acute events than the now currently used degree of stenosis. Therefore, we evaluated a dedicated software tool for volume measurements of atherosclerotic carotid plaque and its components in multidetector computed tomography angiography (MDCTA) images. Materials and Methods Data acquisition was approved by the Institutional Review Board and all patients gave written informed consent. MDCTA images of 56 carotid arteries were analyzed by three observers. Plaque volumes were assessed by manual drawing of the outer vessel contour. The luminal boundary was determined based on a Hounsfield-Unit (HU) threshold. The contribution of different components was measured by the number of voxels within defined ranges of HU-values (calcification >130 HU, fibrous tissue 60–130 HU, lipid core <60 HU). Interobserver variability (IOV) was assessed. Results Plaque volume was 1,259 ± 621 mm3. The calcified, fibrous and lipid volumes were 238 ± 252 mm3, 647 ± 277 mm3 and 376 ± 283 mm3, respectively. IOV was moderate with interclass correlation coefficients (ICC) ranging from 0.76 to 0.99 and coefficients of variation (COV) ranging from 3% to 47%. Conclusion Atherosclerotic carotid plaque volume and plaque component volumes can be assessed with MDCTA with a reasonable observer variability

Pseudomonas aeruginosa amidase: Aggregation in recombinant Escherichia coli

The effect of cultivation parameters such as temperature incubation, IPTG induction and ethanol shock on the production of Pseudomonasaeruginosa amidase (E.C.3.5.1.4) in a recombinant Escherichia coli strain in LB ampicillin culture medium was investigated. The highest yield of solubleamidase, relatively to other proteins, was obtained in the condition at 37 degrees C using 0.40 mM IPTG to induce growth, with ethanol. Our results demonstrate the formation of insoluble aggregates containing amidase, which was biologically active, in all tested growth conditions. Addition of ethanol at 25 degrees C in the culture medium improved amidase yield, which quantitatively aggregated in a biologically active form and exhibited in all conditions an increased specific activity relatively to the soluble form of the enzyme. Non-denaturing solubilization of the aggregated amidase was successfully achieved using L-arginine. The aggregates obtained from conditions at 37 degrees C by Furier transform infrared spectroscopy (FTIR) analysis demonstrated a lower content of intermolecular interactions, which facilitated the solubilization step applying non-denaturing conditions. The higher interactions exhibited in aggregates obtained at suboptimal conditions compromised the solubilization yield. This work provides an approach for the characterization and solubilization of novel reported biologically active aggregates of this amidase

Determinants of outcome in operatively and non-operatively treated Weber-B ankle fractures

Introduction: Treatment of ankle fractures is often based on fracture type and surgeon's individual judgment. Literature concerning the treatment options and outcome are dated and frequently contradicting. The aim of this study was to determine the clinical and functional outcome after AO-Weber B-type ankle fractures in operatively and conservatively treated patients and to determine which factors influenced outcome. Patients and methods: A retrospective cohort study in patients with a AO-Weber B-type ankle fracture. Patient, fracture and treatment characteristics were recorded. Clinical and functional outcome was measured using the Olerud-Molander Ankle Score (OMAS), the American Orthopaedic Foot and Ankle Society ankle-hindfoot score (AOFAS) and a Visual Analog Score (VAS) for overall satisfaction (range 0-10). Results: Eighty-two patients were treated conservatively and 103 underwent operative treatment. The majority was female. Most conservatively treated fractures were AO-Weber B1.1 type fractures. Fractures with fibular displacement (mainly AO type B1.2 and Lauge-Hansen type SER-4) were predominantly treated operatively. The outcome scores in the non-operative group were OMAS 93, AOFAS 98, and VAS 8. Outcome in this group was independently negatively affected by age, affected side, BMI, fibular displacement, and duration of plaster immobilization. In the surgically treated group, the OMAS, AOFAS, and VAS scores were 90, 97, and 8, respectively, with outcome negatively influenced by duration of plaster immobilization. Conclusion: Treatment selection based upon stability and surgeon's judgment led to overall good clinical outcome in both treatment groups. Reducing the cast immobilization period may further improve outcome

Ranking of Fuzzy Similar Faces Using Relevance Matrix and Aggregation Operators

AbstractIn perception based imaging, Sketching With Words (SWW) is a well-established methodology in which the objects of computation are fuzzy geometric objects (f-objects).The problem of facial imaging of criminal on the basis of onlooker statement is not lack of method and measures but the modeling of onlooker(s) mind set. Because the onlooker has to give statements about different human face parts like forehead, eyes, nose, and chin etc.The concept of fuzzy similarity (f-similarity) and proper aggregation of components of face may provide more flexibility to onlooker(s). In proposed work onlooker(s) statement is recorded. Thereafter it is compared with existing statements. The f-similarity with different faces in database is estimated by using ‘as many as possible’ linguistic quantifier. Three types of constraints over size of parts of face ‘small’, ‘medium’, and ‘large’ are considered. Possibilistic constraints with linguistic hedges and negation operator like ‘very long’, ‘not long’, ‘not very long’ etc. are used. Moreover we have generated ranking of alike faces in decreasing order by using the concepts of f-similarity and relevance matrix

How do COPD patients respond to exacerbations?

<p>Abstract</p> <p>Background</p> <p>Although timely treatment of COPD exacerbations seems clinically important, nearly half of these exacerbations remain unreported and subsequently untreated. Recent studies have investigated incidence and impact of failure to seek medical treatment during exacerbations. Yet, little is known about type and timing of other self-management actions in periods of symptom deterioration. The current prospective study aims at determining the relative incidence, timing and determinants of three types of patient responses.</p> <p>Methods</p> <p>In a multicentre observational study, 121 patients (age 67 ± 11 years, FEV₁pred. 48 ± 19) were followed for 6 weeks by daily diary symptom recording. Three types of action were assessed daily: planning periods of rest, breathing techniques and/or sputum clearing (type-A), increased bronchodilator use (type-B) and contacting a healthcare provider (type-C).</p> <p>Results</p> <p>Type-A action was taken in 70.7%, type-B in 62.7% and type C in 17.3% of exacerbations (n = 75). Smokers were less likely to take type-A and B actions. Type-C actions were associated with more severe airflow limitation and increased number of hospital admissions in the last year.</p> <p>Conclusions</p> <p>Our study shows that most patients are willing to take timely self-management actions during exacerbations. Future research is needed to determine whether the low incidence of contacting a healthcare provider is due to a lack of self-management or healthcare accessibility.</p