https://hdl.handle.net/123456789/52 Thu, 14 May 2026 10:57:59 GMT 2026-05-14T10:57:59Z https://hdl.handle.net/20.500.14279/36223 Title: Development and Assessment of Collagen-Based Biomaterials for Wound Healing Applications Authors: Bileri, Maria Ioanna Abstract: There is an increasing need for new and effective therapies that can support skin regeneration and improve wound healing. Regenerative medicine is increasingly focusing on the development of bioengineered materials that interact dynamically with the wound microenvironment to enhance the healing process. Among these emerging technologies, collagen-based biomaterials have gained widespread attention due to their inherent biocompatibility, biodegradability, and structural similarity to the extracellular matrix. This study, carried out in collaboration with local biotech SMEs (Promed Bioscience Ltd, Theramir Ltd and RSL Revolutionary Labs), aims to evaluate how formulation, composition, and structural complexity affect the physicochemical and microstructural properties of atelocollagen materials and hydrogels, to identify the best candidates for biomedical use for wound healing. Atelocollagen formulations with different compositions and concentrations (A, D, X3, Combo) were assessed through methods such as measurements of viscosity, osmolality, swelling, dissolution, contact angle, and Scanning Electron Microscopy (SEM) to analyze fibrillar morphology. Hydrogel formulations (T40, T41, T43) based on Combo atelocollagen were tested too. A preliminary in vivo study using the hydrogel was also performed, helping to establish the protocol for future large-scale animal studies. Among the atelocollagen samples, the Combo (a blend of D and X3 atelocollagens) showed the most balanced properties, offering good hydration control and mechanical stability, whereas the A formulation exhibited weak consistency and high dissolvability. Hydrogel T41 exhibits better behavior in terms of swelling stability, suggesting superior moisture retention and compatibility with physiological conditions. The results suggest that changes in the composition of atelocollagen can make a big difference in how it holds moisture, how strong it is, and how well it interacts with biological fluids. These features are essential for supporting wound healing. Combo collagen and T41 hydrogel were identified as the most promising formulations for further development. Preliminary in vivo studies in animal models showed faster and more visible wound healing compared to untreated cases, confirming their potential for skin regeneration applications. Mon, 01 Dec 2025 00:00:00 GMT https://hdl.handle.net/20.500.14279/36223 2025-12-01T00:00:00Z https://hdl.handle.net/20.500.14279/36222 Title: Dynamic 4D-CT Angiography post-EVAR for Early Detection, Classification, and Management of Endoleaks Authors: Panayiotou, Natalie Abstract: Abdominal aortic aneurysms are defined as an abnormal, irreversible dilatation of the abdominal aorta typically exceeding 3 cm in the greatest diameter or more than 50% of its normal anteroposterior diameter. The primary minimal intervention treatment of abdominal aortic aneurysms are endovascular aneurysm repairs. Endoleak is considered the most commonly occurring complication after EVAR, thus demanding frequent post operative follow-ups.Endoleaks represent persistent perfusion into the residual aneurysm sac, that may lead in sac expansion. Therefore, accurate diagnosis of endoleak type using adequate imaging surveillance or re-intervention is crucial for better long-term survival rates. The main aim of this study is to evaluate an innovative customized dynamic CTA imaging protocol for the early detection, classification, and management of endoleaks following endovascular aneurysm repair of abdominal aortic aneurysms. The establishment of this protocol improves the accuracy and confidence in detecting or excluding the presence of endoleaks. Triphasic conventional computed tomography angiography protocol, routinely performed for endovascular aneurysm repair surveillance involves three static images of unenhanced, arterial and delayed venous phase. However, the variability in contrast arrival and washout time and the complexity of the stent graft for each patient in CT imaging precludes accurate characterization of endoleak type and identifying target vessels for the treatment of safe and targeted re-intervention. In recent years, advanced dual-source dual-energy CT systems with alternating table positions allow for dynamic acquisitions of the endograft's hemodynamics, the aneurysm sac, and all the aortic branches with a continuous visualization of the contrast media flow, thus detecting with accuracy the type of endoleak. Ten patients scheduled for their routine CTA examination of the abdominal aorta post EVAR at German Oncology Center, were prospectively studied. Two patients were excluded from the study because of the absence of endoleaks. This retrospective study was approved by the local Bioethics committee (2023.01.166) and all participants provided written informed consent before the examination. vii The patients were examined with a time-resolved CT angiographic protocol consisting of 12 low-dose phases with 60-80 mL of iodine contrast media. A dual energy acquisition was obtained as a delayed scan having the valuable benefits of the two x-ray photon energy spectra. Even when the venous phase was acquired too late or too early and contrast washed out, the application of virtual monoenergetic images and iodine maps increased the visualization of contrast enhancement. The dynamic series were assessed with the use of syngo. CT Dynamic Angio and syngo. CT Body Perfusion application in order to analyze them quantitatively and qualitatively and provide quantitative parameters to maximize the accuracy of the endoleak source. The venous dual energy series were assessed with the use of syngo. CT Dual Energy application to identify any minimal, low flow endoleaks. The dCTA revealed eight type II endoleaks and one type I endoleak. The analysis, conducted using dynamic CT angiography, revealed a significant difference in the mean enhancement between the aorta and endoleak. Certain endoleaks have a slow flow, appearing between 40 to 44 seconds after contrast injection, while others manifest as early leaks, detected between 24 to 37 seconds. The phase with the best contrast enhancement among the 12 phases of our time-resolved CTA protocol showed a mean attenuation value in the aortic lumen for all the patients 737.8 HU. The mean attenuation value of the aneurysm sac (noise) was 47 HU. Mean attenuation value of the endoleak was 555 HU. The average contrast-to-noise ratio of the aortic lumen for all the dynamic CTA phases was 16 and the average CNR of the endoleak was 11.8. All patients did not have a significant change in their aneurysm sac diameter except patients 6 and 10 who had a 19.6% increment of the aneurysm diameter and 12.9% respectively. Also, the same patients had a significant SVG with both the manual volumetric measurement method of the aneurysm sac and the ellipsoid method. The mean protocol radiation dose was 1134 mGy cm and the mean effective dose was 17.0 mSv. The overall average score of the quality assessment, encompassing evaluations from all the radiologists, was reported as 4 categorizing the protocol as ‘good’. The systematic review of the published studies designates that, the DLP of the dynamic CTA protocol, which includes a noncontrast phase, a dynamic phase with 12 series, and a dual-energy venous phase, is in most cases significantly lower than the conventional CTA protocol. Additionally, the contrast media volume being given to the patients with dynamic CTA protocols was significantly lower than the contrast media volume of the viii cCTA protocol due to the lowest tube kV used in the dynamic CTA protocol. This ustocustomized dynamic CT protocol had a lower contrast dose compared to other publications and a lower/comparable radiation dose. The thesis concludes that 4D CTΑ with the use of quantitative analysis regarding perfusion maps showed excellent diagnostic accuracy and demonstrated feasibility in objective endoleak analysis and can aid the differential diagnosis of endoleak types. This study introduces a novelty protocol that combines dynamic CTA and dual energy for evaluating the presence of endoleaks. Furthermore, no other study or publication has employed both the ellipsoid and volumetric methods to measure sac volume growth and subsequently compared these values. Additionally, no other assessment of endoleak revealed endoleak iodine concentration values extracted from the dual energy iodine maps. Some future perspectives for this thesis involve expanding the patient sample size to enable a more comprehensive evaluation of the protocol across a larger population and explore additional perfusion parameters to ascertain whether the endoleak represents a high or low-risk leakage based on these perfusion values. Also, iodine concentrations can provide a potential biomarker for diagnosis of a sac enlargement or a high/low flow endoleaks. Mon, 01 Jan 2024 00:00:00 GMT https://hdl.handle.net/20.500.14279/36222 2024-01-01T00:00:00Z https://hdl.handle.net/20.500.14279/35466 Title: Mathematical and Computational Modeling of Metal Ion Release from Cardiovascular Implants Authors: Vrakas, Dimitris Abstract: In biomedical engineering, ensuring the safety and efficacy of implants through rigorous testing procedures is paramount. The majority of metal alloys used for cardiovascular implants contain high levels of nickel, which, if released in sufficient quantities, can lead to several adverse local as well as systemic effects. To assess general corrosion susceptibility and metal ion release, the US Food and Drug Administration (FDA) recommendations include testing per the American Standard of Testing and Materials (ASTM) F2129-08, F3306-19, and G31-72(2004). Modeling and simulation tools represent a promising approach to improve the nonclinical testing methods employed in the Toxicological Risk Assessment (TRA) of medical devices. This thesis utilizes physics-based equations, stochastic modeling, and computation simulations to complement and supplement the use of in vitro experiments. Physics-based equations will be used as prediction tools on current reported data, which include varying post-processing techniques, varying chemical conditions, application of mechanical stress, and different fabrication methods. Stochastic modeling (Monte-Carlo probabilistic simulations) will address how data are reported in these protocols and their possible use in predictive models. Lastly, computational simulations will be developed to obtain diffusion coefficients and concentration of nickel as these are difficult to measure experimentally. Applying the above shows that post-processing techniques and external factors, such as stress and chemical conditions of immersion, influence nickel ion release. This is evident by the parameters and data fitting predictions obtained by the tested physics-based equations. Parameters are then incorporated into the Monte Carlo simulations to be used as inputs that consist of a range of values, with the ultimate goal of assisting in better nickel release predictions when combined with larger and more complex predictive models. Lastly, computational simulations have proven useful in providing approximate values of diffusion coefficients of nickel in the surrounding medium and surface Ni concentration, both of which are critical to nickel ion release. Wed, 01 May 2024 00:00:00 GMT https://hdl.handle.net/20.500.14279/35466 2024-05-01T00:00:00Z https://hdl.handle.net/20.500.14279/34946 Title: Διερεύνηση χρήσης και ανάγκης χρήσης μορφών Επαυξητικής και Εναλλακτικής Εναλλακτικής Επικοινωνίας σε παιδιά με εγκεφαλική παράλυση στην Κύπρο Authors: Λεωνίδου, Νάταλη Abstract: Εισαγωγή: Περίπου 50% των παιδιών με εγκεφαλική παράλυση παρουσιάζουν δυσκολίες στην ομιλία και τον λόγο, οι οποίες επηρεάζουν την καταληπτότητα της ομιλίας τους. Αυτό καθιστά συχνά αναγκαία τη χρήση μορφών Επαυξητικής και Εναλλακτικής Επικοινωνίας (ΕΕΕ). Η παρούσα μελέτη είναι η πρώτη που συλλέγει δεδομένα στην Κύπρο σχετικά με το αναπτυξιακό προφίλ αυτών των παιδιών και τις μορφές επικοινωνίας που ήδη χρησιμοποιούν ή χρειάζονται. Σκοπός: Η έρευνα στόχευσε στη διερεύνηση της χρήσης και ανάγκης χρήσης μορφών ΕΕΕ σε παιδιά με εγκεφαλική παράλυση, ηλικίας 4-12 ετών, που παρακολουθούνται από λογοθεραπευτές στον δημόσιο ή ιδιωτικό τομέα στην Κύπρο. Μεθοδολογία: Συμμετείχαν 14 λογοθεραπευτές που υποστήριζαν 20 παιδιά με εγκεφαλική παράλυση. Η μελέτη ακολούθησε μικτή μεθοδολογία με συλλογή ποιοτικών και ποσοτικών δεδομένων, μέσω τριών ερωτηματολογίων (Αναπτυξιακό προφίλ, Κλίμακα Ταξινόμησης Ομιλίας Viking, ερωτηματολόγιο ΕΕΕ) και ημι-δομημένης συνέντευξης. Οι συναντήσεις πραγματοποιήθηκαν δια ζώσης ή διαδικτυακά, με διάρκεια περίπου 30 λεπτών. Η ανάλυση των δεδομένων έγινε με τη χρήση του Excel. Αποτελέσματα: Τα παιδιά που δε χρησιμοποιούν αλλά διαφάνηκε πως χρειάζονται μορφές ΕΕΕ, παρουσίασαν ηπιότερες δυσκολίες στο αναπτυξιακό τους προφίλ και ταξινομήθηκαν στα Επίπεδα Ι και ΙΙ της Κλίμακας Ταξινόμησης Ομιλίας Viking. Αντίθετα, όσα παιδιά χρησιμοποιούν ήδη αυτές τις μορφές επικοινωνίας αντιμετωπίζουν σοβαρότερες δυσκολίες σε όλους τους τομείς, εκτός από την ακοή και κατατάχθηκαν στα Επίπεδα ΙΙΙ και ΙV. Οι συνηθέστερες μορφές επικοινωνίας που χρησιμοποιούν είναι οι εκφράσεις του προσώπου. Μεταξύ των υποβοηθούμενων μορφών, κυριαρχούν οι ταμπλέτες ή υπολογιστές με λογισμικό ΕΕΕ, αν και η χρήση τους είναι λιγότερο συχνή σε σχέση με τις μη υποβοηθούμενες μορφές επικοινωνίας. Η επιλογή των κατάλληλων μορφών επικοινωνίας δεν βασίζεται αποκλειστικά στις ατομικές δυσκολίες του παιδιού, αλλά επηρεάζεται επίσης από προσωπικούς, περιβαλλοντικούς, κοινωνικοοικονομικούς και πρακτικούς παράγοντες. Συμπεράσματα: Τα ευρήματα επιβεβαιώνουν την ετερογένεια στο αναπτυξιακό προφίλ των παιδιών με εγκεφαλική παράλυση και υπογραμμίζουν την ανάγκη για περαιτέρω έρευνα με μεγαλύτερο δείγμα. Description: Introduction: Approximately 50% of children with cerebral palsy experience speech and language difficulties, which affect their speech intelligibility. This frequently necessitates the use of Augmentative and Alternative Communication (AAC) forms. This study is the first to collect data in Cyprus regarding the developmental profile of these children and the forms of communication they currently use or need. Aim: The aim was to investigate the use and need for AAC forms in children with cerebral palsy, aged 4-12 years, who are supported by speech and language therapists in the public or private sector in Cyprus. Methodology: Fourteen speech and language therapists who supported twenty children with cerebral palsy participated in the study. A mixed-methods approach was employed, collecting both qualitative and quantitative data through three questionnaires (Developmental Profile, Viking Speech Scale, AAC questionnaire) and semi-structured interviews. The meetings were conducted either in person or online, lasting approximately 30 minutes. Data analysis was carried out using Excel. Results: Children who are not currently using but appear to need AAC forms, exhibited milder difficulties in their developmental profiles and were classified at Levels I and II of the Viking Speech Scale. In contrast, children who already use AAC forms face more severe difficulties across all domains, except hearing, and were classified at Levels III and IV. The most common unaided forms of communication are facial expressions. Among the aided forms, tablets or computers with AAC software predominate, although their use is less frequent compared to unaided forms. The selection of appropriate communication forms is not solely based on the child’s individual difficulties, but is also influenced by personal, environmental, socio-economic and practical factors. Conclusions: The findings confirm the heterogeneity in the developmental profiles of children with cerebral palsy and highlight the need for further research with a larger sample. Thu, 01 May 2025 00:00:00 GMT https://hdl.handle.net/20.500.14279/34946 2025-05-01T00:00:00Z