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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
111

In Vitro Induction Of Growth And Development Of Common Juniper (juniperus Communis L.) From Shoot And Bud Explants

Kocer, Zeynep Ahsen 01 January 2005 (has links) (PDF)
The objective of the study was to investigate the optimum conditions for in vitro regeneration of common juniper (Juniperus communis L.) by using indirect organogenesis approach. Throughout the study / callus induction, organogenesis, improved organogenesis and root induction experiments were performed sequentially. It was found that explant position, genotype, gender, treatments and sampling time had significant effects on callus induction rate in common juniper. The results of treatments indicated that IBA (indole-3-butyric acid) at concentration range 0.5-4.0 mg/l combined with MS medium supplemented with 0.1 mg/l BAP (benzylaminopurine), 3 % sucrose and 0.7% agar was the best one among the treatments to induce callus formation from common juniper explants collected as Spring buds. Also, a two-month culture was adequate period for the callus induction of common juniper regardless of position, before transferring the explants into organogenesis media. After a two-month culture in callus induction media, explants were transferred to organogenesis treatments in order to investigate adventitious bud development from callus tissues. There were significant differences among genotypes, treatments and explant-sampling times in initiation of organ development in common juniper. Additionally, it was found that excluding the auxin components while maintaining 1.0-2.0 mg/l BAP concentration in culture media, as refreshing after a month, stimulated the formation and development of adventitious buds and shoots. Among the treatments tested, it was found that 1.0 mg/l BAP plus 0.5 mg/l 2,4-D was the optimum culture media with adventitious bud formation capacity of 37.5% was though ageing of callus significantly affected the frequency of adventitious bud formation. Finally, rooting experiments were performed to investigate rooting efficiency of adventitious shoots. In the adventitious rooting experiments, no rooting was observed in any of the treatments used with common juniper explants. Although whole plantlet development from callus tissues could not be achieved as indirect organogenesis, the results of the study could aid to future studies dealing in vitro regeneration and production of secondary chemicals from common juniper.
112

Preparation And Characterization Of Poly(d,l-lactide-co-glycolide) Microspheres For Controlled Release Of Anticancer Drugs

Eyovge, Gokcen 01 August 2005 (has links) (PDF)
Breast cancer is the most frequent type of cancer seen in woman. Chemotherapy is one of the most important treatments for breast cancer. However, systemic toxicity, drug resistance and unstable kinetics of the drug in the blood are serious problems of chemotherapy. The use of biodegradable polymers for controlled release of anticancer drugs has gained popularity in recent years. Controlled release of anticancer drugs from polymeric carriers has some advantages such as improvement in the efficiency of treatment, reduction in systemic toxicity and prevention of the drug resistance that is developed by the cancer cells. In this study, it was aimed to prepare such a controlled release system for anticancer drugs which are used in breast cancer treatment by using biodegradable copolymer poly(D,L-lactide-co-glycolide) and to characterize in terms of morphology, size, drug content and drug release rate. In the first part of this study / empty and drug loaded poly (D,L-lactide-co-glycolide) microspheres were prepared. Two sets of empty poly(D,L-lactide-co-glycolide) microspheres were prepared by solvent evaporation technique with single emulsion (oil/water) to determine the effect of stirring rate on size of microspheres. Increase in stirring rate caused decrease in size of microspheres. Drug loaded poly(D,L-lactide-co-glycolide) microspheres were prepared for controlled release of anticancer drugs which are used in breast cancer treatment namely / 5-fluorouracil, methotrexate and tamoxifen by using solvent evaporation technique either with double emulsion (water/oil/water) or single emulsion (oil/water). In the second part of this study / empty and drug loaded microspheres were characterized. Inverted light microscopy and scanning electron microscopy were used to examine morphology and size of microspheres. Drug content of microspheres and amount of released drug were determined and drug release profile was obtained for each anticancer drug separetely.
113

Dublin Medieval Dendrochronology

Baillie, Michael G. L. January 1977 (has links)
Large scale urban excavations since 1969 have yielded timber structures, within archaeological contexts of the 10th to 14th centuries, in the City of Dublin. Two oak chronologies have resulted from dendrochronological work in the area spanning A.D. 885 to 1306 and A.D. 1357 to 1556. These chronologies should allow the precise dating of oak timbers from subsequent excavations in the area and will form the basis of an eventual continuous Dublin chronology.
114

An Oak Chronology for South Central Scotland

Baillie, Michael G. L. January 1977 (has links)
The chronology presented was constructed in the hope of answering two specific questions. It was intended to assess the potential of dendrochronology in an area where no previous investigations had taken place. In addition it was necessary as a step towards assessing the cross agreements between different areas within the British Isles. The resulting 1030 year chronology has shown the potential usefulness of the method in Scotland and allowed the suggestion of larger tree -ring areas within the British Isles than have previously been supposed.
115

The Belfast Oak Chronology

Baillie, Michael G. L. January 1977 (has links)
The initial tree-ring chronology for the north of Ireland extended to A.D. 1380. Considerable difficulty was experienced in consolidating an extension back across the 14th century. This difficulty, partially founded on historical factors, has now been resolved and suitable timbers have been obtained to allow the presentation of the Belfast chronology to A.D. 1001.
116

Studies On The Mechanism Of Resistance Against Pyrethroids In Helicoverpa Armigera: Molecular And Proteomic Approach

Konus, Metin 01 September 2012 (has links) (PDF)
Helicoverpa armigera is an insect, causes important economical losses in crops. To reduce this loss, chemical insecticides such as pyrethroids have been commonly used against H. armigera in farming areas all over the world. However, excess and continuous usages of them cause resistance development in H. armigera. Insects develop resistance against applied insecticides by following three main mechanisms / by reducing the amount of insecticide entering into the insect body, developing insensitivity of the insecticide effective site and increasing detoxification metabolism of insecticides such as increased metabolism of them in midgut tissue of H. armigera. Therefore, changes in differentially expressed midgut proteins were analysed at protein level with two-dimensional gel electrophoresis (2D-PAGE) and matrix-assisted laser desorption/ionization-time-of-flight-mass spectrometry (MALDI-TOF-MS) together with examine biochemical activity changes of certain detoxification enzymes such as esterases (EST) and glutathione S-transferases (GST). Moreover, transcriptional level analysis of certain genes from EST and GST systems together with cytochrome P450 monooxygenases (CYP450) system were done with quantitative real-time PCR method, too. According to the comparative proteome analysis, it was found that H. armigera field samples overcome pyrethroid stress mainly by increasing energy metabolism related proteins expressions such as ATP synthase, Vacuolar ATPase A and B and arginine kinase proteins. Furthermore, certain detoxification enzymes such as thioredoxin peroxidase and NADPH cytochrome P450 reductase were up-regulated in Mardin population, suggesting that they were actively participating in response to pyrethroid stress. NADPH cytochrome P450 reductase could play a role in detoxification of toxic pyrethroid metabolites such as 3-phenoxybenzaldehyde. However, while glutathione S-transferases (GSTs) were not found up-regulated in the comparative proteome analysis, biochemical assays (GST-CDNB, GST-DCNB and GST-PNBC) showed significant increases in enzyme activities in the Adana and in the Mardin field population, as compared to the susceptible strain. Furthermore, GST-DCNB and GST-PNBC activities showed significant increase in &Ccedil / anakkale population. As overcoming energy crisis may lead to an increase in oxidative stress, detoxification enzymes (GSTs and thioredoxin peroxidase) might be involved in pathways for eliminating toxic reactive oxygen species such as H2O2. Similarly, although esterases (EST) were not found as differentially expressed, biochemical assays for ESTs showed significant increases in enzymatic activities in the Adana and the Mardin field populations. Thus, ESTs are also proposed to be involved in developing resistance as an initiator of pyrethroid metabolism in H. armigera from Turkey. Quantitative real-time PCR results showed that while CYP9A14 gene expression was up-regulated in all analyzed field populations, CYP9A12 gene expression was up-regulated in both &Ccedil / anakkale and Mardin populations. CYP4S1 gene expression was also up-regulated only in Mardin field population. However, while CYP6B7 gene expression together with CYP9A12 and CYP4S1 genes expressions were down-regulated in Adana population, CYP6B7 gene expression was not significantly changed in both &Ccedil / anakkale and Mardin populations. In addition, GST, GSTX01 and ESTX018 gene expressions were not significantly changed in all field populations in comparison to susceptible population. Therefore, CYP9A14, CYP9A12 and CYP4S1 genes proposed to be involved in detoxification of toxic pyrethroid metabolites possibly through regulation of NADPH cytochrome P450 reductase. In conclusion, it is suggested that one of the main mechanisms of resistance development is increased energy metabolism in the midgut tissue of H. armigera which may be a general prerequisite for compensating the costs of energy-consuming detoxification processes.
117

Molecular Investigation Of Ptz-induced Epileptic Activities In Rat Brain Cell Membranes And The Effects Of Vigabatrin

Turker Gorgulu, Sevgi 01 August 2009 (has links) (PDF)
The epilepsies are a heterogenous group of symptom complexes, whose common features is the recurrence of seizures. There is no certain therapy for epilepsy. In order to promote new advances for the prevention of epilepsy the molecular mechanism of epileptic activities should be clarified. In the present study the goal is to obtain information for molecular mechanism of epilepsy. To achieve this, molecular alterations from pentylenetetrazol (PTZ)-induced epileptic activities on rat brain tissue and cell membranes were investigated by Fourier Transform Infrared (FTIR) spectroscopy, Fourier Transform Infrared Microscopy and Atomic Force Microscopy (AFM). Moreover, the therapeutic role of an antiepileptic agent vigabatrin (VGB) on epileptic rat brain membranes were examined at molecular level. For better understanding of the action mechanism of PTZ and an antiepileptic drug VGB in cell membranes we firstly studied at model level using multilamellar liposomes (MLVs). We investigated PTZ-DPPC MLVs interactions in terms of lipid phase behavior, order and dynamics and nature of hydrogen bonding around its polar part, using Fourier Transform Infrared (FTIR) spectroscopy, Differential Scanning Calorimetry (DSC), Electronspin Resonans Spectroscopy (ESR) and Steady State Fluorescence Spectroscopy. According to our data, PTZ has no ability to interact with membrane lipids. On the other hand, the results of VGB-DPPC interactions showed that VGB strongly interact with the head group and/or the region near the head of membrane phospholipids. The molecular investigation of PTZ-induced epileptic activities revealed that PTZ-induced seizures cause a decrease in the lipid and protein content, membrane fluidity and glycogen level. They stimulate alterations in membrane packing and the secondary structure of proteins as well as lipid peroxidation. In addition, our results show the transcription of early genes following high dose PTZ administration. All these molecular alterations variatins are only resulted from the consequences of epileptic activities not from convulsant agent PTZ itself. The important finding is that, VGB restored some of the alterations by PTZ-induced epileptic activities on brain cell membrane. For instance, it restored membrane fluidity, lipid peroxidation, phospholipid degradation and changes in membrane organization. However, it was found that VGB has no significant effects on the changes in protein secondary structure.
118

Studies On Novel Immunogenic Proteins Of Clostridium Chauvoei

Coral, Didem 01 December 2009 (has links) (PDF)
Clostridium chauvoei is a gram-positive, spore-forming anaerobic bacterium. It is the pathogenic agent of blackleg, a disease causing serious toxemia and high mortality in cattle, sheep and many other domestic and wild animals. It is considered the most important Clostridium producing economic losses in livestock. Typically, animals infected with blackleg die rapidly without any signs of illness. Animals quickly die within 12 to 48 hours after contracting the disease. Therefore, the control of this disease is done by commercial vaccines consisting of whole formolized cultures. Immunity against C. chauvoei is associated with whole cell, including its somatic and flagellar antigens while in other clostridial diseases, protective immunity is obtained by the use of vaccines containing toxoids. Moreover, it is essential to obtain new information about the somatic antigens of C. chauvoei. Proteomics is the study of the proteome, the protein complement of the genome. The proteome has been defined as the entire complement of proteins expressed by a cell, organism, or tissue type, and accordingly, proteomics is the study of this complement expressed at a given time or under certain environmental conditions. 2-DE with Immobilized pH Gradients (IPGs) combined with protein identification by Mass Spectrometry (MS) is currently the workhorse for proteomics. Much of information about immunogenic component can be derived from proteomics coupled to Western blotting, namely immunoproteomics. Our study constitutes the first immunoproteomic analysis of C. chauvoei to identify candidate immunogenic antigens for development of new vaccines. Analyses were performed by Western blot and dot blot techniques against the whole cell extract proteins of C. chauvoei separated by 2-DE. Firstly, the growth conditions of two different strains, C. chauvoei ATCC 11957 and C. chauvoei 20 were optimized. After mice immunization studies with experimental vaccines prepared, sera were obtained for evaluation of the immunoglobulin G antibody level by ELISA. After high level of antibody response determination, 1-DE, 2-DE and immunoblot studies were performed for the characterization of immunogenic proteins. In the study, a total of 460 protein spots could be detected on the 2-DE gels by the help of Delta2D image analysis software and 30 of them were reacted with polyclonal antibodies against inactivated whole cells of C. chauvoei. Among these 30 spots, and 8 of them could be characterized by MALDI-TOF MS analyses. Of these 8 spots revealed four different gene products (distinct ORFs). Ornithine decarboxylase, methionine adenosyltransferase, glucose-6-phosphate isomerase, and flagellin protein FliB (C) are the characterized proteins. Glucose-6-phosphate isomerase has been identified as an immunogenic protein for a pathogenic microbe and in C. chauvoei for the first time. Methionine adenosyltransferase and ornithine decarboxylation were identified as immunogenic for C. chauvoei for the first time. The last defined protein is the flagellin protein FliB(C) which is known to be major immunogenic protein of C. chauvoei.
119

Study Of Bone Characteristics And Muscle Quality In Metabolic Disorders

Bozkurt, Ozlem 01 July 2012 (has links) (PDF)
Although the effects of diabetes on bone mineral content has been studied, little is known about the structural alterations in collagen, maturation of apatite crystals and carbonate content in diabetic bone. The first part of this study aimed to investigate the mineral and organic properties of cortical, trabecular and growth plate regions of rat femur tissues in type I diabetes using FTIR microspectroscopy and Vickers microhardness test. A decrease in mineral content (degree of mineralization), decrease in microhardness, increase in carbonate content, increase in size and maturation of hydroxyapetite crystals, which are the implications of increased osteoporosis, were observed in diabetic bone. In addition, a decreased carbonate substitution into bone apatite and an increase in labile type carbonate was observed in diabetic bone. There was a decrease in the level of crosslinking of collagen in cortical and trabecular regions of diabetic femurs, implying a decrease in bone collagen quality that may contribute to bone fragility. Recent evidence implies that intramyocellular lipid accumulation is directly correlated with insulin resistance, a key parameter in the generation of obesity. The second part of this study is mainly focused on the determination of the structural and compositional characterization of macromolecules of longissimus dorsi and quadriceps muscles of Berlin fat mouse inbred (BFMI) lines using ATR-FTIR spectroscopy and FTIR microspectroscopic imaging, together with the quantification of fiber specific distribution of lipids in these muscles by the use of confocal microscopy. The study groups included 10 weeks old standard breeding diet fed (juvenile) and 20 weeks old high fat diet fed control and BFMI lines. The results revealed the loss of unsaturation in lipids, increased triglyceride content, increased amount of lipids having shorter chain length, increased lipid peroxidation and fiber specific accumulation of lipids in type IIa and intermediate fibers in skeletal muscles of both 10 weeks old and 20 weeks old BFMI lines, emphasizing their obese phenotype. However, the alterations were more prominent in skeletal muscles of 20 weeks old high fat diet fed BFMI lines, displaying a more severe obesity phenotype. The results of the characterization revealed that BFMI860 and BFMI861 lines are convenient models for the study of spontaneous obesity and studies to enlighten the genetic basis of obesity.
120

Biochemical, Cytotoxic And Genotoxic Effects Of Aescin On Human Lymphocytes And Hl-60 Promyeloid Leukemia Cell Line

Topsoy Kolukisa, Serap 01 July 2005 (has links) (PDF)
Aescin is a mixture of several acidic triterpenoid saponin glycosides found in the extracts of the horse chestnut tree. Horse chestnut, Aesculus Hipoocastanum, is one of the 25 domestic species of Aesculus that are mostly large, ornamental shade trees. Although known to be poisonous, the nuts of the horse chestnut are used by Amerindians, after detoxification. Horse chestnuts are said to have several traditional medicinal usages including even cancer. In this study the biochemical, genotoxic, and cytotoxic effects of aescin was studied using isolated lymphocytes, whole blood lymphocytes and HL-60 promyeloid leukemia cell lines. Cytotoxicity of aescin was examined by trypan blue viability staining of the cells in culture treated with varying aescin concentrations. It was observed that aescin was cytotoxic at all concentrations, for all cell types studied, except whole blood lymphocytes, where it was not cytotoxic at 10-9 and 10-10 M concentrations. Genotoxicity of aescin was examined by sister chromatid exchange and micronucleus. The genotoxic effect of Aescin was observed to be more significant over isolated lymphocytes compared to other cell lines. On the otherhand, aescin at 10-8 M and lower concentrations were observed to be non-genotoxic over whole blood lymphocytes whereas this concentration was considerably toxic for isolated lymphocytes and for HL-60 cell lines. Apoptotic properties of aescin were determined by DNA fragmentation, cytochrome c release and negative NAPO staining. All the Aescin concentrations tested resulted in apoptosis over HL-60 cell lines, whereas necrosis was not observed. However, isolated lymphocytes showed both apoptosis and necrosis upon treatment with 10-6 M to 10-8 M aescin, exhibiting apoptosis only at 10-9 M and 10-10 M. Biochemical effects of aescin were investigated by following GST and NAT enzyme activities. An increase in GST enzyme activity was observed over all cell lines treated with increasing aescin concentrations for 72 hours. Whereas NAT activity was decreased upon treatment with aescin in similar manner.

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