published_or_final_version / Biochemistry / Master / Master of Philosophy

published_or_final_version / Orthopaedic Surgery / Master / Master of Philosophy

Η συγκεκριμένη εργασία επικεντρώνεται στην εκτίμηση της καταλληλότητας κάποιων μαγματικών πετρωμάτων ως αδρανή υλικά για συγκεκριμένες χρήσεις και κυρίως για την κατασκευή βάσεων – υποβάσεων σε έργα οδοποιίας. Η έρευνα αφορούσε διαβασικά και δακιτικά πετρώματα από γεωϋλικά της περιοχής Μεθάνων καθώς και από την περιοχή Αγίων Θεοδώρων. Στα δείγματα αυτά αξιολογήθηκε η καταλληλότητά τους με βάση τα αποτελέσματα ποιοτικού ελέγχου που περιλάμβανε όλες τις σχετικές εργαστηριακές δοκιμές και απαιτήσεις που ορίζονται στα αντίστοιχα Ευρωπαϊκά Πρότυπα (ΕΝ), συγκεκριμένα:  Γεωμετρικές ιδιότητες (κοκκομετρική ανάλυση, δείκτης πλακοειδούς και ισοδύναμο άμμου)  Φυσικές ιδιότητες (φαινόμενη πυκνότητα και υγρασία απορρόφησης)  Μηχανικές ιδιότητες (δείκτης Micro-Deval, δείκτης LAΑV, δείκτης AIV)  Παράμετροι αντοχής βραχώδους υλικού Από τα αποτελέσματα της εργαστηριακής έρευνας διαπιστώνεται ότι τα συγκεκριμένα μαγματικά πετρώματα κρίνονται γενικά σαν «ακατάλληλα» για την κατασκευή βάσεων αλλά και υποβάσεων για οδοποιία, σύμφωνα με τις Ελληνικές και διεθνείς απαιτήσεις ποιότητας. Αυτό οφείλεται κυρίως στις αυξημένες τιμές του δείκτη LAAV που εκφράζει την αντοχή του γεωϋλικού σε μηχανική φθορά και κρούση. Εξαίρεση αποτελεί δείγμα από συγκεκριμένη θέση που χαρακτηρίζεται σαν «υψηλής ποιότητας». Επιπρόσθετα, από τις συσχετίσεις που δοκιμάστηκαν μεταξύ των επιμέρους ιδιοτήτων των γεωϋλικών διατυπώνονται εμπειρικές σχέσεις τόσο μεταξύ των μηχανικών όσο και των γεωμετρικών ιδιοτήτων. / This thesis focuses on the evaluation of the suitability of specific igneous rocks used as aggregates for uses as bases and subbases in road construction. Our research was carried out on diabasic and dacitic rocks obtained from the areas of Methana and Saint Theodore. The quality control of the tested samples were conducted under the specific guidelines of EN <European Standards>, while the procedure was refered to estimation of the following parameters:  Geometrical properties (grain size analysis, flakiness index and sand equivalent)  Physical properties (apparent density and water absorption)  Mechanical properties (Micro - Deval index, LAAV index, AIV index)  Rock material strength parameters. The laboratory testing results led to the conclusion that the samples of the geomaterial examined can be classified as "not suitable" as bases and subbases in road construction according to Greek and international specifications. The high values of the LAAV index which represent the strength of geomaterials in mechanical corrosion and crush mainly contribute to the low quality of the geomaterials. The only exception was a sample from a specific area that characterized as "high quality". Furthermore, correlations between the properties of the geomaterials were evaluated and empirical equations regarding the mechanical as well as the geometrical properties of the geomaterials were established.

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The development of a new class of antihistamines, the H2-receptor antagonists, introduced a new era in the treatment of peptic ulcer diseases. Cimetidine, the first clinically effective H2-blocker, was introduced in 1976. Recently ranitidine, a second member approved for clinical use, has been found to be as effective as cimetidine in the management of peptic ulcer diseases. Soon after the introduction of cimetidine several reports of loss of libido, impotence and gynaecomastia were described in male patients who were on normal or high therapeutic doses of cimetidine. A few unsubstantiated reports of loss of libido and gynaecomastia attributed to ranitidine therapy have also appeared in literature. This study was undertaken to examine in detail the effects of acute and subchronic treatment with cimetidine and ranitidine on mating behaviour in sexually active male rats. Motor activity counts were recorded immediately before sexual behaviour observations. The animals were tested on every third day and observations were terminated after the first intromission of the next series of copulations. In the single dose study, mating behaviour tests were commenced 2 hours after treatment; mating tests during the subchronic dose studies were done 4 to 7 hours after the 6hOO dose. The following measures were used in the analysis of data: mount latency, intromission latency, mount frequency, intromission frequency, ejaculation latency, and the postejaculatory intromission latency. At the termination of the subchronic dose studies blood samples were collected by cardiac puncture and the animals were subsequently autopsied. Cauda epididymal sperm counts and motility were determined, testes and accessory sex organs were weighed, and one testis was processed for histological examination. Cimetidine in the low dose, 128.6 mg/kg, significantly shortened the ejaculatory latency and to a lesser extent the postejaculatory intromission latency. At the higher dose, 257.1 mg/kg, cimetidine markedly prolonged the postejaculatory intromission latency and to a lesser extent increased the ejaculation latency. The inhibitory effect of cimetidine on copulatory behaviour at the higher dose level was accompanied by significant depression in motor activity. At the conclusion of the subchronic dose studies marked reductions in serum testosterone levels and decreased testes and accessory organ weights were observed in the cimetidine group. No significant changes in sperm counts were observed, although the sperm counts in the cimetidine group were lower than the control values. Histological examination of testes showed apparently normal spermatogenesis in all three treatment groups. However, in spite of the reduced testosterone levels and decreased testes and accessory sex organ weights in the cimetidine group, no impairment in mating behaviour was observed. In both the acute and the subchronic dose studies, similar to placebo, treatment with ranitidine showed no effect on mating behaviour. On final analysis of the results it is concluded that cimetidine, and not ranitidine, disrupts sexual behaviour in male rats. Furthermore, it is concluded that the effect of cimetidine on sexual behaviour is not related to H2-receptor blockade as equipotent doses of ranitidine did not produce similar effects. The mechanism of cimetidine-induced impairment of sexual performance in the male rat may possibly be attributed to some non-specific, direct or indirect action of cimetidine on some neurotransmitter system responsible for the control of sexual behaviour. It is further suggested that the effect may possibly be mediated by a blockade of central dopamine receptors. However, it must be stressed that further experimentation is necessary to elucidate the mechanism of action of cimetidine on sexual behaviour. / Thesis (M.Sc.)-University of Durban-Westville, 1985.

Atherosclerosis is a complex disease which develops silently over decades and can lead to acute myocardial infarction or stroke, the main cause of death worldwide. Apoliporotein E (apo E) is a glycoprotein known for its major role in lipid metabolism and its pro-atherogenic effects. Swine make a unique and viable research model as it shares most of the anatomic and physiologic characteristics with humans, notably for the the cardiovascular system. In addition, it is the only animal species, other than nonhuman primates, that develops atherosclerosis spontaneously. In this study we examined the feasibility for creating an apo E-deficient pig model of atherosclerosis using RNA interference (RNAi) and somatic cell nuclear transfer (SCNT). The knockdown efficiency was tested in porcine granulosa cells. It varied from 45% to 82% compared to control cells, as revealed by real-time PCR analysis. Accordingly, short hairpin RNA-expressing vectors were constructed and used to transfect porcine fetal fibroblast cells. Cell lines with stable chromosomal integration were established and used to produce embryos by SCNT. Development of SCNT embryos to the blastocyst stage (33%) was comparable to non-transgenic embryos. The integration of the shRNA into the genome of GFP-expressing embryos was revealed by PCR and gel electrophoresis. These findings indicate that porcine embryos harboring shRNA-specific to apo E created by SCNT may lead to the production of apo E-deficient pigs. These pigs would be a promising new animal model for advancing atherosclerosis research.