Emodin (1,3,8-trihydroxy-6-methylanthraquinone) is a phytoestrogenic component of Rheum plant extracts which has been used for medical treatment since ancient times. It has been shown to have anti-inflammatory and anti-cancer effects. In our research, we aimed to study the biological effects of emodin on MCF-7 and MDA-231 cell lines. Cytotoxicity assays showed that emodin treatment for 48hours caused a concentration dependent decrease in viable cell numbers of both cell lines. As determined by cell counting with tryphan blue, IC50 values were 8.40 and 12.17 &micro / g/ml for MCF-7 and MDA-231 cells, respectively. Apoptotic effects of emodin was investigated by measuring the changes in apoptotic and antiapoptotic gene expressions by qRT-PCR. In MCF-7 cells, Bax expression increased with increasing emodin concentrations, while Bcl-2 expression was downregulated. Bax/Bcl-2 ratio was calculated as 9.2 fold at 10&micro / g emodin/ml treatment for 48 hours, indicating stimulation of apoptosis. However, Bax/Bcl-2 ratio was found 1.6 fold for MDA-231 cells. These results were in accordance with the results obtained from microarray analysis of related gene expressions. MCF-7 cells were more apoptotic in comparison to MDA-231 cells. DNA fragmentation was observed in MCF-7 cells by TUNEL method. GST enzyme activity that was measured using CDNB as substrate, was increased 100% with respect to control up to 5&micro / g emodin/ml treatment of MCF-7 cells for 48 hours. However, effect of emodin on GST activity in MDA-231 cells was found insignificant. According to microarray analysis results, emodin affected the gene expressions of GST isozymes in MCF-7 cells much more than in MDA-231 cells.

Rheum species are medicinally important plants due to the presence of anthracene derivatives and in this study antioxidative, cytotoxic, apoptotic and chemopreventive characteristics of R. ribes extracts were evaluated. R. ribes shoot and root dry powder samples were prepared and extracted with ethyl acetate, ethanol and water. The extracts were revealed to be a potential scavenger of DPPH radicals and the chemical composition of the extracts was quantified by colorimetric determination of total phenol (GAE) and flavonoid (CAE) contents. HL&ndash / 60 cells were cultured in the presence of various concentrations of extracts up to 72 hr. R. ribes inhibited the surviv al of HL-60 cells in a concentration- and time-dependent manner, shown by trypan blue and XTT. R. ribes caused HL-60 cells apoptosis via formation of phosphatidylserine externalization, as evidenced by flow cytometry. Exposure of HL-60 cells to higher concentrations of extracts for 72 h resulted in a shift of 87% of the cell population from normal to the early/late apoptotic stage. The R. ribes induced apoptosis may be partially attributed to the activation of caspase-3 and up-regulation of caspase-3 expression was detected in western blot. The significant release of cytochrome c from the mitochondria into the cytosol was observed. The mRNA expression ratio of Bax/Bcl-2 was increased. The apoptosis was also demonstrated by DNA ladder and TUNEL. Chemopreventive effects of R.ribes were investigated at the gene level of CYP1B1 and CYP1A1, and GST enzyme activity against cDNB and concluded that R.ribes modulated activities of these enzymes generally at a time dependent level. T h ese findings suggest that Rheum ribes exhibits potential antioxidant and anticancer properties by inducing caspase-dependent cell death in HL-60 cells.

Meniscus is a wedge shaped structure, with a convex base attached to a flat tibial surface, and with a concave femoral surface, on which femur and tibia articulate. It has several functions including joint lubrication, shock absorption, load transmission and joint stability. Various methods were tried to treat meniscal tears but each has its own drawbacks. Tissue engineering seems to be a promising solution that avoids all the problems associated with the other approaches. In this study, a three dimensional (3D) collagen-based structure was prepared by tissue engineering to mimic the natural human meniscus. Three different foams prepared under different conditions were combined and nano/microfibrous layers were placed in between them. To mimic the properties of the natural tissue, the top layer was composed of collagen-chondroitin sulfate-hyaluronic acid (Coll-CS-HA) prepared by freezing at -20&ordm / C followed by lyophilization. The middle and bottom layers were made with just collagen after freezing at -20&ordm / C and -80&ordm / C, respectively and lyophilization. Aligned nano/microfibers were prepared using collagen-poly(L-lactic-co-glycolic acid (Coll-PLGA). Various crosslinking procedures such as 1-ethyl-3-(3-dimethylaminopropyl) carbodiimide/N-hydroxysuccinimide (EDC/NHS), genipin (GP), glutaraldehyde (GLU) either alone or in combination with dehydrothermal treatment (DHT) were used and based on both compressive and tensile properties, the best crosslinker was chosen to be DHT+EDC/NHS. Mechanical properties (compressive, tensile and shear) of the dry foams and the final 3D construct were evaluated. The highest mechanical properties were obtained with the 3D construct. Then all these foams and the 3D construct were seeded with human fibrochondrocytes to study the cell behavior such as attachment, proliferation, and extracellular matrix (ECM) and glucosaminoglycan (GAG) production. Furthermore, the influence of cell seeding on the compressive properties of wet individual foams and the 3D construct was observed. As expected, the highest cell proliferation and compressive properties were obtained with the 3D construct. Finally, the 3D constructs, seeded with fibrochondrocytes, were implanted in New Zealand rabbits after meniscectomy. The initial microscopical examination show that the 3D construct has a significant potential as a meniscus substitute.

Quantum dots (QDs) are increasingly attracting attention in recent years due to their potential in biological imaging and drug delivery applications. Despite their significant advantages over organic dyes and fluorescent proteins, cytotoxicity is still a major problem in live-cell QD labeling. In this work, in-vitro characterization of a novel CdTe/2MPA quantum dot capped with CdS-DMSA was conducted on human cervical cancer (HeLa) and mouse fibroblast (NIH/3T3) cell lines. Biocompatibility of this novel particle was evaluated in comparison to a commercial quantum dot (Qdot 565) and various QDs with CdTe core. Cytotoxicity of quantum dots was investigated using XTT and proliferation assays. Cellular internalization and localization of particles were studied using confocal laser scanning microscopy. For quantitative determination of internalization and intracellular QD stability, we also performed uptake and cadmium release assays. Optimal cell imaging concentration with CdTe-CdS/2MPA-DMSA was determined as 10-50 ug/mL in HeLa cells. Localization of the internalized QD particles was observed in the perinuclear region of the cells. XTT and proliferation assays provided identical viability results for the tested QDs. CdS-DMSA capping increased cytocompatibility of CdTe/2MPA by 15% in NIH/3T3 cells. Biocompatibility of this capped particle was further increased by 3-folds with pegylation. For pegylated CdTe-CdS/2MPA-DMSA and commercial Qdot 565, we have not observed QD-related cytotoxicity on NIH/3T3 cells following 24-hr QD exposure at 50 ug/mL. Our in-vitro characterization studies indicate that CdTe-CdS/2MPA-DMSA is a promising live-cell imaging probe which can be effectively excited in the visible range of the electromagnetic spectrum.

ABSTRACT INVESTIGATON OF CHEMOPREVENTIVE PROPERTIES OF URTICA DIOICA L., IN MCF-7 AND MDA231 BREAST CANCER CELL LINES. G&uuml / ler, Elif Ph.D., Biological Sciences Department Supervisor : Prof. Dr. Mesude

Drug delivery systems are designed to achieve low, local doses at the target site. Delivery systems can provide the drug in a continuous manner or in response to environmental stimuli such as temperature, pH or UV. This study aimed to develop photosensitive liposomes that achieve UV-responsive release of their content. The main mechanism was to incorporate a light sensitive molecule into the liposomal bilayer then achieve destabilization of the membrane by exposure to UV. This would result in an on demand release of the bioactive content. Suprofen, a nonstereoidal anti-inflammatory drug, also a light sensitive molecule, was selected to achieve the destabilization in this study. Lipid vesicles were prepared with different ratios of phosphatidyl choline, cholesterol and Suprofen (PC:CHOL:SPF) and characterized in terms of encapsulation efficiency, release rate and responsiveness to UV. Preliminary studies were carried out with calcein (CAL), a fluorescent dye, due to the ease of detection and the in vitro studies were carried out with the cancer drug Cisplatin.

Colorectal carcinoma (CRC) is one of the most common cancers and is the leading cause of cancer deaths in much of the developed world. Owing to the high incidence of drug resistance and potential toxic effects of chemotherapy drugs, much research is currently underway to design better strategies for smart drug delivery systems. Cyclooxygenase-2 (COX-2) pathway is associated with poor prognosis in colon carcinomas. The selective COX-2 inhibitor drug Celecoxib (CLX) has been shown to posses COX-2 independent anti-carcinogenic effects in addition to inhibition of prostaglandins synthesis. The aim of the presented thesis was to develop a liposomal delivery system for CLX and to evaluate functional effects in CRC cell lines. Starting with multilamellar vesicles capable of CLX encapsulation and retention, nano sized liposomes were prepared and characterized in vitro. The optimum composition was determined as 10:1 DSPC: Cholesterol molar ratio and Polyethylene glycol (PEG) grafting at 2% of phospholipids. The extent of cellular association of PEGylated liposome formulation was analyzed quantitatively and cellular localization was analyzed qualitatively. We detected that CLX loaded PEGylated liposomes inhibited proliferation and cellular motility of cancer cells in a 2D model system. Our results showed that, Epidermal Growth Factor Receptor (EGFR) targeted CLX loaded immunoliposomes were extremely cytotoxic in cancer cells with high EGFR expression but not in cells devoid of EGFR expression. This delivery system may pioneer studies that may potentially circumvent the harmful systemic side effects of cancer preventive and chemotherapy drugs as well as allow the use of targeted combinatorial therapies.

Turkey is on the main migratory route for many bird species although especially passerine migration is little known. The objective of this study is to document and analyze the diversity, abundances, daily and seasonal phenologies of migrating passerines at METU as well as compare seasonal phenologies with those obtained at Manyas KuScenneti(Balikesir) and Cernek(Samsun) stations. The study covers autumn 2001, spring and autumn 2002 migration seasons. Methodology is based on the capture and ringing of passerines. In the first two seasons, intermittent sampling was the rule, but in autumn 2002 the study was continuous throughout the day and the season. Totally 1,832 individuals of 60 passerine species were ringed. Blackcap (Sylvia atricapilla) and Willow Warbler (Phylloscopus trochilus) were the two most common species. Blackcap dominates species composition in autumn seasons with a very high percentage (%33). Daily captures peaked in the early morning and with a smaller peak one hour before the sunset. Several waves of migrants were detected in autumn 2002, with most peaks in close correlation with those recorded at Cernek station, indicating some connection between migrant populations using both sites for stopover. Fat depositon rates showed at least Yalincak is a high quality stopover site for most migrant species since many species gained weight up to around 50% within a period of 10 days. This is the first study documenting passerine migration in Turkey, and it revealed that small wooded landscapes within less hospitable habitats provide crucial stopover habitat for many migrant passerines.

SCREENING FOR ANTIOXIDANT ACTIVITIES OF SEVERAL MEDICINAL PLANT EXTRACTS AND THEIR EFFECTS ON GLUTATHIONE-S-TRANSFERASE ACTIVITY ABSTRACT Sagdi&ccedil / oglu Celep, A. G&uuml / l&ccedil / in Ph.D., Department of Biochemistry Supervisor: Assoc. Prof. Nursen &Ccedil / oruh May 2005, 154 pages The consumption of fresh fruits, vegetables, and medicinal plants are known to be associated with a long life span and low incidence of oxidative stress related diseases such as Alzheimer&amp / #8217 / s, Parkinson&amp / #8217 / s, cancer, aging and cardiovascular diseases. Fitotherapeutic effects of medicinal plants is virtually attributable to their phenolic compounds with low cytotoxicity. In this study, plants used in Anatolian folk medicine for their effects such as antiinflammatory, antiulcer, antipyretic, fertility, analgesic and aphrodisiac, namely Aesculus hippocastanum L., Papaver bracteatum L., Urtica urens L., Gundelia tournefortii L., Prangos ferulacea L., Chaerophyllum macropodum Boiss., Heracleum persicum Desf., Allium vineale L., Aconitum cochleare Woroschin, Rheum ribes L., Ferula rigidula DC., Rosa heckeliana Tratt, were screened for their antioxidative effects. Antioxidant characteristics of the specified plants were studied using lipid peroxidation inhibiton and DPPH radical scavenging methods. Total phenolics content and their effects on glutathione-S-transferase activity of the plants were further investigated. Rheum ribes L, Ferula rigidula DC, Rosa heckeliana Tratt., Prangos ferulacea L. were found to be very effective antioxidants and also effective inhibitors for glutathione-S-transferase activities among the plants. Rosa heckeliana Tratt. root extracts exhibited very high total phenolics content (0.7 mg/mg of extract) and antioxidant activity with IC50 values of 11.2 &micro / g/mL and 5.1 &micro / g/mL for DPPH scavenging and lipid peroxidation inhibition, respectively. Ferula rigidula DC was identified as the most potent inhibitor for glutathione-S-transferase activity, with IC50 values of 49 &micro / g/mL.

This study investigated the 9th grade students&#039 / achievement regarding diffusion and osmosis in relation to reasoning ability, prior knowledge and gender. A total of 397 ninth grade students participated in the study. The Test of logical thinking (TOLT) and the Diffusion and Osmosis Diagnostic Test (DODT) were administered to determine students&#039 / reasoning ability and achievement in diffusion and osmosis, respectively. DODT results showed that the range of correct answers for the first tier was 41 % to 91%. When both tiers were combined, the correct responses were reduced to a range of 21% to 61%. This result reveals that students have enough content knowledge but they don&rsquo / t know the underlying reason of their choice in diffusion and osmosis concepts. Pearson Product Moment correlations showed a statistically significant positive correlation between achievement and students&#039 / prior knowledge &amp / reasoning ability. MRC Analysis was conducted to determine the contribution of prior knowledge, reasoning ability and gender to the achievement. Prior knowledge and reasoning ability, but not gender, made a statistically significant contribution to the variation on achievement. Prior knowledge and reasoning ability together predicted 37 % of the variation on achievement. Stepwise multiple regression analysis was computed to determine the variables were best predicting students&rsquo / achievement. While prior knowledge explains 33 % of the variation in achievement, reasoning ability explains only 4 % of the variation in achievement. Results indicate that prior knowledge is a better predictor than reasoning ability in students&rsquo / achievement.