Pregnancy in dialysis patients: a case series

Fertility is markedly reduced in patients with chronic renal failure. For women with pre-existing renal disease, pregnancy is associated with an increased rate of fetal complications and a considerable risk of renal disease progression. Due to substantial improvements in antenatal and neonatal care, fetal outcome has improved considerably in the last two decade

Methods on LDL particle isolation, characterization, and component fractionation for the development of novel specific oxidized LDL status markers for atherosclerotic disease risk assessment

The present study uses simple, innovative methods to isolate, characterize and fractionate LDL in its main components for the study of specific oxidations on them that characterize oxidized low-density lipoprotein (oxLDL) status, as it causatively relates to atherosclerosis-associated cardiovascular disease (CVD) risk assessment. These methods are: (a) A simple, relatively time-short, low cost protocol for LDL isolation, to avoid shortcomings of the currently employed ultracentrifugation and affinity chromatography methodologies. (b) LDL purity verification by apoB100 SDS-PAGE analysis and by LDL particle size determination; the latter and its serum concentration are determined in the present study by a simple method more clinically feasible as marker of CVD risk assessment than nuclear magnetic resonance. (c) A protocol for LDL fractionation, for the first time, into its main protein/lipid components (apoB100, phospholipids, triglycerides, free cholesterol, and cholesteryl esters), as well as into LDL carotenoid/tocopherol content. (d) Protocols for the measurement, for the first time, of indicative specific LDL component oxidative modifications (cholesteryl ester-OOH, triglyceride-OOH, free cholesterol-OOH, phospholipid-OOH, apoB100-MDA, and apoB100-DiTyr) out of the many (known/unknown/under development) that collectively define oxLDL status, which contrasts with the current non-specific oxLDL status evaluation methods. The indicative oxLDL status markers, selected in the present study on the basis of expressing early oxidative stress-induced oxidative effects on LDL, are studied for the first time on patients with end stage kidney disease on maintenance hemodialysis, selected as an indicative model for atherosclerosis associated diseases. Isolating LDL and fractionating its protein and main lipid components, as well as its antioxidant arsenal comprised of carotenoids and tocopherols, paves the way for future studies to investigate all possible oxidative modifications responsible for turning LDL to oxLDL in association to their possible escaping from LDL’s internal antioxidant defense. This can lead to studies to identify those oxidative modifications of oxLDL (after their artificial generation on LDL), which are recognized by macrophages and convert them to foam cells, known to be responsible for the formation of atherosclerotic plaques that lead to the various CVDs

The Image of Small Island Santorini as a 'Tourism Destination' as Percieved by International Tourists.

The study was conducted with the purpose of exploring the image of Santorini, a small Greek island, held by international travellers before and after visit experiences. This research identifies an extensive theoretical framework around the concepts of Tourism, and more specifically, Island Destinations; Destination Image and; Travel Consumer Behaviour. These will serve as the foundation on which the current investigation can be built and the hypotheses developed. A sample of 106, international (non-Greek) tourists aged 18 and over, who had been on the island for at least two days at the time of the research, was investigated by a questionnaire survey. The statistical analysis of the responses generated by the questionnaires was done with the employment of SPSS software program and the use of several techniques, such as Frequencies, Cross-tabulations, Independent Samples t-tests and Paired Samples t-tests. The analysis provided data about the respondent’s demographics and psychographics, the factors influencing their destination choice, and finally the pre and after visit images the respondents held of Santorini. Overall, there was a higher response rate by female visitors; the majority of respondents fell under the two age groups of 25-44 and 45-64, were Americans and medium income earners, had received high levels of education, hold high working positions and traveled independently. Furthermore, the analysis identified that the respondents considered the several destination attributes given (local culture, cost of life and travel, e.t.c.) as fairly important to their finally destination choice. The perception of these factors was found to be affected mostly by respondents’ income, but also age and gender. Furthermore, the most popular sources of information as used by the entire group of respondents were found to be their friendly environment, travel guides and the Internet; however, age was found to influence the sources used. On the whole, the most popular activities, as answered, came out to be the island’s beaches, archaeological/historic sites and the visit to the volcano. Finally, the 5 Hypotheses that were tested for the purpose of this research indicated that the image held by tourists for the island before their visit was averagely positive, and became even more positive after their visit; and that the overall attitudes towards the island constituted of their expectations being met and satisfied. The respondents’ age and gender were not found to influence the perceptions and views created

Development of novel clinical markers for the assessment of atherosclerotic diseases development in humans

The present doctorate thesis has led to the development of simple and innovative methodologies for the isolation, characterization and fractionation of low density lipoproteins (LDLs) into their main molecular components. The ultimate aim of this thesis is to study/measure the specific oxidative modifications present on LDL components, that characterize the oxidized LDL (oxLDL) particles, which in turn are causally related to the development of atheromatous plaques and therefore to the risk of subsequent cardiovascular diseases (CVDs). The methods developed in the present thesis include: (a) A simple, relatively fast and low-cost method for the isolation of LDL particles (LDLP)from human blood serum, in order to avoid the disadvantages of the currently used ultracentrifugation and affinity chromatography methods. (b) Confirmation of the purity of the, isolated with the proposed methodology, LDL-P through SDS-PAGE electrophoresis of their protein component (apolipoprotein B100, apoB100), and determination of the size of LDL-P. The latter as well as the concentration of LDL-P in serum are estimated by means of a developed simple, clinically applicable - in comparison with existing nuclear magnetic resonance (NMR)methodologies - method while their value as risk indicators for the development of CVDs is also evaluated. (c) A method for the fractionation of LDL, for the first time, into its individual protein/lipid (apoB100, cholesterol esters, triglycerides, free cholesterol, phospholipids) and antioxidant (carotenoids, tocopherols) components. (d) Methods for the quantification, for the first time, of certain specific - representative of the initial effects of oxidative stress - oxidative modifications/markers in the molecular components of LDL (cholesteryl ester-OOH, triglyceride-OOH, free cholesterol-OOH, phospholipid-OOH, apoB100- MDA, apoB100-DiTyr), out of the many (known/unknown/under development) oxidative modifications that collectively characterize the oxidative state of oxLDL. These methods for oxLDL state evaluation differ significantly when compared to the existing non-specific and unreliable methods for assessing the oxidative status ofoxLDL. The aforementioned oxLDL markers are being studied for the first time in patients prone to atherosclerosis development as well as in patients with established atherosclerotic lesions and CVDs. Specifically, the selected patient groups include: patients with chronic kidney disease(CKD) on hemodialysis, patients with CKD on peritoneal dialysis, patients with abdominal aortic aneurysm patients and patients with carotid artery disease. Additionally, within the framework of the present thesis, a structural study of the apoB100 protein of LDL particles was carried out, as this remains a poorly studied protein with an unknown structure. Initially, a biophysical characterization of the solubilized apoB100 was performed by studying its secondary structure (by circular dichroism analysis, CD analysis), its thermal stability (by differential scanning fluorescence, nanoDSF) and the existence of aggregates in its solution (by dynamic scattering light, DLS). The biophysical characterization of apoB100 was followed by LCP (Liquid Cubic Phase) crystallization screens of the protein and measurement of the resulting crystals by X-ray diffraction. In summary, the isolation of LDL particles and their fractionation into their individual protein, lipid and antioxidant components paves the way for future studies regarding the investigation and quantification of all possible LDL oxidative modifications and thus paves the way for the full characterization of the so far unknown oxidative status of oxLDL particles. This may also lead to further studies for the identification of the oxLDL modifications that are responsible for their recognition by the macrophages and the impending transformation of the latter into foam cells, which are responsible for the formation of atherosclerotic lesions that in turn lead to the development of CVDs. Lastly, the biophysical characterization experiments and the LCP crystallization screens of apoB100, performed for the first time in the framework of this thesis, are the trigger for further apoB100 crystallization studies that will lead to the solving the so far unknown structure of apoB100 and to the elucidation its function and role in the development of atherosclerotic lesions.Η παρούσα διδακτορική διατριβή οδήγησε στην ανάπτυξη απλών και καινοτόμων μεθοδολογιών για την απομόνωση, το χαρακτηρισμό και την κλασμάτωση των λιποπρωτεϊνών χαμηλής πυκνότητας (LDL) στα κύρια μοριακά τους συστατικά. Απώτερος σκοπός της παρούσας διατριβής είναι η μελέτη σε αυτά συγκεκριμένων οξειδωτικών τροποποιήσεων οι οποίες χαρακτηρίζουν τα αιτιακώς σχετιζόμενα με την ανάπτυξη αθηρωματικών πλακών και άρα και με τον κίνδυνο εμφάνισης των επακόλουθων καρδιαγγειακών παθήσεων, οξειδωμένα LDL (oxLDL) σωματίδια. Οι αναπτυχθείσες στην παρούσα διατριβή μέθοδοι περιλαμβάνουν: (α) Μία απλή, σχετικά γρήγορη και χαμηλού κόστους μέθοδο για την απομόνωση των LDL σωματιδίων (LDL-P) από τον ορό του αίματος, προς αποφυγή των μειονεκτημάτων των έως τώρα εφαρμοζόμενων υπερφυγοκεντρικών μεθόδων και μεθόδων χρωματογραφίας συγγένειας. (β) Επιβεβαίωση της καθαρότητας των απομονωμένων με την προτεινόμενη μεθοδολογία LDL, μέσω SDS-PAGE ηλεκτροφόρησης της πρωτεΐνης αυτών (απολιποπρωτεΐνη Β100, apoB100), και προσδιορισμός του μεγέθους των LDL-P. Το τελευταίο καθώς και η συγκέντρωση των LDL-P στον ορό υπολογίζονται στην παρούσα διατριβή μέσω μίας αναπτυχθείσας απλής, κλινικά εφαρμόσιμης μεθόδου - σε σύγκριση με τις υπάρχουσες μεθοδολογίες μαγνητικού πυρηνικού συντονισμού (NMR) – ενώ αξιολογείται και η αξία τους ως δείκτες εκτίμησης του κινδύνου εμφάνισης καρδιαγγειακών παθήσεων. (γ) Μία μέθοδος για την κλασμάτωση των LDL, για πρώτη φορά, στα επιμέρους πρωτεϊνικά/λιπιδικά (apoB100, εστέρες χοληστερίνης, τριγλυκερίδια, ελεύθερη χοληστερίνη, φωσφολιπίδια) και αντιοξειδωτικά (καροτενοειδή, τοκοφερόλες) συστατικά τους. (δ) Μέθοδοι για την ποσοτικοποίηση, για πρώτη φορά, ορισμένων συγκεκριμένων - αντιπροσωπευτικών των αρχικών επιδράσεων του οξειδωτικούς στρες - οξειδωτικών τροποποιήσεων/δεικτών στα μοριακά συστατικάτων LDL (cholesteryl ester-OOH, triglyceride-OOH, free cholesterol-OOH, phospholipid-OOH,apoB100-MDA, apoB100-DiTyr) εκ των πολλών (γνωστών/άγνωστων/υπό ανάπτυξη) οξειδωτικών τροποποιήσεων που συλλογικά χαρακτηρίζουν την οξειδωτική κατάσταση των oxLDL. Οι μέθοδοι αυτοί έρχονται σε αντίθεση με τις υπάρχουσες μη-εξειδικευμένες και αναξιόπιστες μεθόδους γιατην αξιολόγηση της οξειδωτικής κατάστασης των oxLDL. Οι προαναφερθέντες oxLDL δείκτες μελετώνται για πρώτη φορά σε ασθενείς επιρρεπείς στην εμφάνιση και σε ασθενείς με εγκατεστημένες αθηρωματικές πλάκες και καρδιαγγειακές νόσους. Συγκεκριμένα, οι ομάδες ασθενών που επιλέχθηκαν είναι: ασθενείς με χρόνια νεφρική νόσο υπό αιμοκάθαρση, ασθενείς με χρόνια νεφρική νόσο υπό περιτοναϊκή κάθαρση, ασθενείς με ανεύρυσμα κοιλιακής αορτής και ασθενείς με στένωση καρωτίδων. Επιπροσθέτως, στα πλαίσια της παρούσας διατριβής πραγματοποιήθηκε δομική μελέτη της apoB100 των LDL σωματιδίων, καθώς αυτή αποτελεί μέχρι και σήμερα μία πρωτεΐνη ελάχιστα μελετημένη και με άγνωστη δομή. Αρχικά, πραγματοποιήθηκε χαρακτηρισμός των βιοφυσικών ιδιοτήτων του διαλύματος της apoB100 μέσω μελέτης της δευτεροταγούς της δομής (με ανάλυση κυκλικού διχρωισμού, CD analysis), της θερμικής της σταθερότητας (με διαφορική φθορισμομετρία σάρωσης, nanoDSF) και της ύπαρξης συσσωματωμάτων στο διάλυμα αυτής (μέσω δυναμικής σκέδασης φωτός, DLS). Έπειτα, ακολούθησαν δοκιμές LCP (Liquid Cubic Phase) κρυστάλλωσης της πρωτεΐνης και μέτρηση των προκύψαντων κρυστάλλων με περίθλαση ακτίνων Χ. Συνοψίζοντας, η απομόνωση των LDL σωματιδίων και η κλασμάτωσή τους στα επιμέρους πρωτεϊνικά, λιπιδικά και αντιοξειδωτικά συστατικά τους ανοίγει το δρόμο για μελλοντικές μελέτες διερεύνησης και ποσοτικοποίησης όλων των πιθανών οξειδωτικών τροποποιήσεων των LDL και συνεπώς του πλήρους χαρακτηρισμού της, άγνωστης μέχρι σήμερα, οξειδωτικής κατάστασης των oxLDL σωματιδίων. Το γεγονός αυτό μπορεί να οδηγήσει σε περαιτέρω μελέτες ταυτοποίησης των οξειδωτικών τροποποιήσεων των oxLDL οιοποίες αναγνωρίζονται από τα μακροφάγα και είναι υπεύθυνες για τη μετατροπή των τελευταίωνσε αφρώδη κύτταρα, τα οποία ευθύνονται για το σχηματισμό των αθηρωματικών πλακών που με τη σειρά τους οδηγούν στην εμφάνιση των καρδιαγγειακών παθήσεων. Τέλος, ο βιοφυσικός χαρακτηρισμός και οι δοκιμές LCP κρυστάλλωσης της apoB100, που πραγματοποιήθηκαν για πρώτη φορά στην υπάρχουσα βιβλιογραφία στην παρούσα διατριβή, αποτελούν το έναυσμα για την πραγματοποίηση περαιτέρω μελετών κρυστάλλωσης της apoB100 με στόχο την επίλυση της, άγνωστης μέχρι σήμερα, δομής αυτής και της διαλεύκανσης της λειτουργίας και του ρόλου της στην ανάπτυξη αθηρωματικών πλακών

Does a 24-hour ultra-swim lead to dehydration?

We investigated the change in body composition and hydration status in one male ultra-endurance swimmer during a 24-hour swim. Body mass, percent body fat and skeletal muscle mass using the anthropometric method as well as total body water using bioelectrical impedance analysis were determined pre race, every 6 hours and after the race. Parameters of hydration status (urinary specific gravity, haematocrit, plasma sodium) and skeletal muscle damage (plasma urea) were measured at the same time. The swimmer achieved a total distance of 41.1 km. Body mass decreased by 1.6 kg, skeletal muscle mass by 1.5 kg, body fat by 2.4 kg and total body water by 3.9 l. Urinary specific gravity remained unchanged at 1.015 g/ml. Haematocrit increased from 46 to 47, plasma volume decreased by 4 % and plasma sodium by 4.0 mmol/l. We found in this ultra-swimmer a decrease in body mass of 1.7 % and a consistent urinary specific gravity of 1.015 g/ml. According to the general concept of dehydration, this corresponds to minimal dehydration