The mechanism of regulation of the Ca²⁺ pump ATPase of the human erythrocyte membrane by calmodulin, cyclic AMP and the anion channel was studied using membrane fragments, resealed "ghosts", inside-out vesicles and a Triton X-100 solubilized enzyme preparation. The (Ca²⁺ + Mg²⁺ )-ATPase activity in erythrocyte membranes or a Triton X-100 solubilized enzyme preparation showed biphasic (high and low affinity) Ca²⁺ activation kinetics. The anionic calcium binding protein, calmodulin, increased both the calcium sensitivity (Kca²⁺) and the maximum velocity (Vmax ) of the enzyme. Certain polyanionic agents (poly-L-aspartic acid, poly-L-glutamic acid), alicyclic sulfonic acids (HEPES,N-2-hydroxyethylpiperazine-N¹-2-ethanesulfonic acid, MES,2-N- (morpholinoethanesulfonic acid)), and aromatic carboxylic acids (benzoic and salicylic acids) increased the Kca²⁺ but not the Vmax of (Ca²⁺ + Mg²⁺ )-ATPase in erythrocyte membranes and Triton X-100 solubilized enzyme preparations. Trifluoperazine (30 μM) antagonized activation of the enzyme by calmodulin and poly-L-aspartic acid, but not by sodium-HEPES or sodium-MES. Limited trypsin proteolysis of (Ca²⁺ + Mg²⁺ )-ATPase in the erythrocyte membrane abolished activation by calmodulin, poly-L-aspartic acid and sodium-HEPES. These results suggest that the modulation of the Ca²⁺ sensitivity of (Ca²⁺ + Mg²⁺ )-ATPase by calmodulin may be associated with the anionic properties of this protein, and that this property can be mimicked by some other anions, probably by interacting at an anion-regulatory site on the enzyme. Cyclic AMP (5 μM) was found to inhibit the (Ca²⁺ + Mg²⁺)-ATPase activity (approx. 20%) in erythrocyte membranes, probably via endogenous cyclic AMP protein kinase, since this effect could be blocked by cyclic AMP protein kinase inhibitor (PKI) from the rabbit skeletal muscle, By contrast, bovine heart PKI stimulated (Ca²⁺ + Mg²⁺ )-ATPase activity (approx. 100%) by increasing the Kca²⁺ but not the Vmax of the enzyme in membrane or Triton X-100 solubilized preparations. At a low calcium concentration the stimulation by bovine heart PKI and saturating levels of calmodulin was additive, suggesting that the two effectors acted by distinct mechanisms. The stimulation of (Ca²⁺ + Mg²⁺ )-ATPase activity by bovine heart PKI was not solely due to its antagonism of the protein kinase because a) modification of arginine residues of bovine heart PKI abolished its inhibition of cyclic AMP protein kinase, but had no effect on the stimulation of (Ca²⁺ + Mg²⁺ )-ATPase; b) trifluoperazine (20 μM) antagonized the stimulation of (Ca²⁺ + Mg²⁺ )-ATPase by PKI, similarly to its antagonism of calmodulin stimulation, but it did not affect the inhibition of protein kinase by PKI. It is suggested that different mechanisms are involved in the inhibition of cyclic AMP protein kinase and the stimulation of (Ca²⁺ + Mg²⁺ )-ATPase by bovine heart cyclic AMP PKI. Next, the role of anion channel blockers on the (Ca²⁺ + Mg²⁺ )- ATPase was studied. The photolabeling reagent N-(4-azido-2-nitrophenyl)- 2 aminoethylsulfonate (NAP-taurine) was found to inhibit the (Ca²⁺+ Mg²⁺ )-ATPase of fragmented red cell membranes. Half maximal inhibition occurred between 25 μM and 50 μM. At these concentrations Mg²⁺ -ATPase and (Na⁺ + K⁺)-ATPase activities in the membranes were not affected. The reversible inhibition of (Ca²⁺ + Mg²⁺ )-ATPase produced by NAP-taurine in the dark became irreversible after photolysis in the presence of this reagent. Incubation of the membranes with Ca²⁺ , Mg²⁺ , ATP or calmodulin, prior to photolysis in the presence of NAP-taurine, did not protect the enzyme from Inhibition. Limited trypsin proteolysis of (Ca²⁺ + Mg²⁺ )-ATPase in fragmented membranes, which abolished activation by calmodulin, did not affect the inhibition by NAP-taurine. NAP-taurine was found to Inhibit the (Ca²⁺ + Mg²⁺ )-ATPase activity from the cytoplasmic side of the membrane, as determined from the following experiments. Addition of NAP-taurine (50 μM) to resealed erythrocyte ghosts inhibited less than 5% of the (Ca²⁺ + Mg²⁺ )-ATPase activity, compared to 50-60% Inhibition in ghosts resealed in the presence of 50 μM NAP-taurine. Furthermore, NAP-taurine inhibited ATP-dependent Ca²⁺ - transport into inside-out vesicles at a similar concentration (50 μM). The inhibition of the (Ca²⁺ + Mg²⁺ )-ATPase activity of membranes by NAP-taurine appeared to be a direct action on the enzyme, rather than through inhibition of the anion channel, as (Ca²⁺ + Mg²⁺ )-ATPase activity was not inhibited in membranes made from red blood cells reacted irreversibly with 50 μM NAP-taurine or the anion channel blocker 4,4'-diisothiocyano- 2,2' stilbene disulfonate (DIDS) (5 μM) or in membranes assayed in the presence of another anion channel blocker, probenecid (125 μM). This is the first reported selective antagonist of the Ca²⁺ pump, and it is suggested that NAP-taurine could be a useful tool for studying the Ca²⁺- transport ATPase in a variety of cells. / Pharmaceutical Sciences, Faculty of / Graduate

Properties of the regulatory nucleotide binding site of the Ca²⁺-ATPase of skeletal muscle sarcoplasmic reticulum have been investigated. Previously, several lines of evidence have indicated the existence of both catalytic and regulatory nucleotide binding sites on the same polypeptide species. The present study concentrates on the interaction of the ATP analogue, 2'-3'-0-(2,4,6-trinitrocyclohexadienylidine) adenosine 5'-triphosphate, (TNP-ATP), with sites on the non-phosphorylated and phosphorylated enzyme. In particular those conformational transitions linking TNP-ATP fluorescence to the phosphoenzyme subspecies have been sought. Previous studies have demonstrated a close relationship between TNP-ATP fluorescence and phosphoenzyme formed from ATP plus Ca²⁺, or from inorganic phosphate (Pi) in the absence of Ca²⁺, in the reverse direction of the cycle. However, the precise relationship of TNP-ATP fluorescence to the energy transducing conformations of the ATPase is controversial. TNP-ATP binding was investigated by spectrophotometric methods and by the synthesis of [ ¹⁴C] TNP-ATP. [ ¹⁴C] TNP-ATP bound to the ATPase site with high affinity ([TNP-ATP] 0. 5 = 0.12 uM), and · a stoichiometry of 5.4 nmol/mg. [ ¹⁴C] ATP binding stoichiometry was 6.1 nmol/mg, demonstrating that TNP-ATP binds to a single family of sites. The nature of the phosphoenzyme intermediate species that results in enhanced TNP-ATP fluorescence was investigated. NEM derivitization, Sr²⁺-transport and Ca²⁺-oxalate uptake have previously been found to alter the distribution or relative levels of phosphoenzyme intermediates. Modification of thiol groups responsible for phosphoenzyme decomposition (SHd), using N-ethylmaleimide (NEM) (0.4 mM) with 50 uM Ca²⁺, 1 mM AMP-PNP at pH 7.0, resulted in a 50% decrease in Ca²⁺-uptake, Ca²⁺-ATPase activity and ADP-insensitive E-P (E₂-P), while total EP (E₁-P + E₂-P = 3.2 nmol/mg), remained unaltered. ATP-dependent TNP-ATP enhanced fluorescence decreased by 50% under these conditions. Ca²⁺-oxalate induced turnover has previously been shown to decrease steady-state E₂-P levels by prevention of Ca²⁺ gradient formation. Oxalate (5 mM) caused a 40% decrease in ATP-induced TNP-ATP fluorescence levels while total EP levels remained relatively unaltered. Previous studies have shown that Sr²⁺-induced turnover favours higher levels of E₂-P by inhibiting the reverse reaction from E₂-P to E₁-P. Strontium-induced turnover increased TNP-ATP fluorescence by 10% as compared to that of Ca²⁺, without affecting steady-state E-P levels, consistent with an E₂-P conformation relationship to enhanced TNP-ATP fluorescence. The binding site for TNP-ATP on the enzyme was investigated by chase studies using millimolar concentrations of nucleotides. ATP and ADP diminished TNP-ATP fluorescence competitively, with apparent Km values of 1.25 and 0.54 mM respectively, consistent with their affinities of binding to the regulatory site. The rates of decrease of fluorescence (25 and 34 sec⁻¹ at 5 ᵒC, respectively), were of the same order of magnitude as the derived "off" rate of TNP-ATP from the site of enhanced fluorescence (33 sec⁻¹), consistent with TNP-ATP being bound to the regulatory site of the enzyme. Enhanced TNP-ATP fluorescence has previously been related to decreased water activity of the probe site. Alteration of water activity by structure- forming (Deuterium oxide) and structure-breaking solutes (KSCN) in relation to fluorescence were explored. Replacement of H₂O by D₂O altered the fluorescence of unbound TNP-ATP. The apparent for TNP-ATP binding to the E₂-P conformation of the regulatory site. The regulatory site appears to be a modified form of the phosphorylated catalytic site. It is proposed that TNP-ATP fluorescence monitors an enzyme conformation related to Ca²⁺ binding to an inward oriented site of low affinity. The mechanism of K⁺ fluorescence quenching appears to be via an acceleration of dephosphorylation, as opposed to a change in affinity of the enzyme for TNP-ATP, as previously suggested. The K⁺ sensitivity of TNP-ATP fluorescence has proved useful in demonstrating a direct interaction of valinomycin with the enzyme through the monovalent cation binding site. Valinomycin appears to bind directly to the enzyme and to selectively accelerate the "off" rate of K⁺ from this site.

In the first part of this study, the kinetics of decay of TNP-nucleotide superfluorescence was investigated with a view to understanding the role of nucleotides and Lys492 in later steps in the catalytic cycle of the skeletal muscle Ca²⁺ATPase. It has been found previously, and verified here, that tethering TNP-8N₃-AMP to the Ca²⁺ATPase via Lys492 retarded the Ca²⁺ initiated decay of Pᵢ-induced superfluorescence 10-fold compared with untethered nucleotide. The rapidity of the decay upon addition of EDTA suggested that the E₂ ↔ E₁ → E₁Ca₂ steps were being monitored rather than dephosphorylation per se. Tethered diand triphospho species did not accelerate the decay. While monophasic kinetics was observed with untethered TNP-AMP and TNP-8N₃-AMP, complex kinetics were observed with the di- and triphospho TNP-nucleotides. This was shown to be due to the utilization of TNP-ADP and -ATP, and the azido derivatives, as coupled substrates of the Ca²⁺ATPase in the forward direction of catalysis in the presence of Ca²⁺. The hydrolysis rates of TNP-ADP, TNP-ATP, TNP-8N₃ -ADP, and TNP-8N₃ -ATP were 10, 5, 15 and 10 nomoles/min/mg of protein, respectively, at room temperature and pH 5.5. Ca²⁺ transport was supported by all four nucleotides. This is the first time that a diphosphonucleotide has been shown to support Ca²⁺ transport. A new nonhydrolysable triphospho TNPnucleotide, TNP-AMP-PCP was synthesized and shown to interact with the Ca²⁺ATPase in a similar way, in terms of superfluorescence, as the other TNP-nucleotides. It did not show the complex kinetics on inhibition of the Pcinduced superfluorescence by Ca²⁺, but neither did it accelerate the kinetics. It was concluded that TNP-nucleotides do not accelerate the E₂ ↔ E₁ transition under these conditions, possibly because of the presence of glycerol in the medium. In the second part of the study, it was shown that addition of small amounts of chelators EGTA, EDTA, BAPTA, DTPA, HEDTA and NTA to a Ca²⁺ transport assay in which the free Ca²⁺ concentration is monitored by Fluo-3 causes the Ca²⁺ATPase to pump to apparently lower levels as seen in the [Ca²⁺] lim fluorescence. Addition of chelator retards pump function in the sense that it takes longer for 50 nmols Ca²⁺ to be accumulated. Increased thermodynamic efficiency of the pump and contaminating heavy metal ions were considered as possible mechanisms. To some extend Zn²⁺ and Cd²⁺, but not Fe²⁺ and Cu²⁺, appeared to reverse the partial inhibition. While interpretation of the results is difficult, it is suggested that heavy metal ions interact with luminal loops of the Ca²⁺ATPase and enhance Ca²⁺ release under conditions of high luminal Ca²⁺ concentrations.

Para avaliação do potencial anestésico do óleo de cravo na mitigação dos efeitos fisiológicos do estresse de exposição aérea e de transporte do lambari, A. altiparanae, foram realizados dois experimentos. No primeiro, fêmeas adultas (n = 80) foram submetidas a quatro tratamentos: controle, anestesia (óleo de cravo 50 mg.L-1), estresse (exposição aérea durante 5 minutos) e anestesia prévia ao estresse. Registraram-se os níveis plasmáticos de cortisol, glicose e lactato, o hematócrito, índice hepatossomático (IHS), as concentrações de glicogênio hepático e muscular branco, a peroxidação lipídica e a atividade das enzimas lactato desidrogenase (LDH), catalase (CAT) e glutationa redutase (GR). Os dados foram submetidos à ANOVA, comparando-se as médias pelo Teste de Tukey (p<0,05). No segundo experimento, avaliaram-se a concentração adequada e os efeitos do anestésico, combinado ou não ao NaCl (sal), sobre as respostas ao estresse de transporte simulado em juvenis (n = 1.269). Foi estabelecido um delineamento inteiramente casualizado, em arranjo fatorial 3x3 (0, 3 e 6 g.L-1 de NaCl; 0, 5 e 7,5 mg.L-1 do anestésico). Os dados foram submetidos à ANOVA com estudo de regressão (p<0,05). No primeiro experimento, observou-se elevação da glicose (53,9%) após a anestesia e/ou o estresse. O estresse elevou os níveis de cortisol (146,6%), de lactato (294,6%) e a peroxidação lipídica no músculo branco (45%) e reduziu o glicogênio muscular (40,1%). O hematócrito aumentou 7,9% após o estresse ou a anestesia. O glicogênio hepático e o IHS não diferiram entre os tratamentos. A anestesia ou o estresse não alteraram a atividade da LDH, mas reduziram a atividade da CAT (46,1%) e da GR (30,3%). No segundo experimento observou-se redução linear da glicose em função das diferentes concentrações de anestésico, na presença de sal (3 g.L-1), e redução quadrática desta variável em função das concentrações crescentes de sal, na presença de anestésico (7,5 mg.L-1). O sal ou anestésico reduziram linearmente o cortisol, entretanto, não houve alteração do hematócrito e do IHS. A adição crescente de sal aumentou linearmente o glicogênio hepático, elevou de forma quadrática o glicogênio muscular e reduziu linearmente o lactato. A anestesia provocou aumento linear do glicogênio muscular e não alterou a peroxidação lipídica, variável que aumentou de forma quadrática em função do acréscimo de sal. A LDH reduziu linearmente, em função das concentrações crescentes de sal, e houve efeito quadrático da interação sal e anestésico nesta resposta. A adição do anestésico provocou redução linear na atividade da CAT e a atividade da GR foi elevada pela interação entre sal e anestésico. Conclui-se que a exposição aérea e o transporte caracterizam-se como agentes estressores em lambaris, reduzindo o bem-estar e a qualidade do pescado. O óleo de cravo na concentração 50 mg.L-1 mitiga as respostas fisiológicas ao estresse e não provoca a peroxidação lipídica, porém não evita esta resposta causada pela exposição aérea. O óleo de cravo e o sal nas concentrações 5 e 7,5 mg.L-1 e 3 a 6 g.L-1, respectivamente, isolados ou associados, são seguros e eficazes para mitigar os efeitos do estresse de transporte no lambari. / The effects of clove oil anesthetic on mitigating the physiological stress responses to air exposure and simulated transporting were evaluated in lambari (A. altiparanae). In the first experiment, adult females (n = 80) were subjected to four treatments: control, anesthesia (clove oil 50 mg L-1), stress (5 min air exposure) and pre-anesthesia associated to stress. Cortisol, glucose and lactate levels, hematocrit, hepatosomatic index (HSI), liver and muscle glycogen content, lipid peroxidation level and the enzymatic activity of lactate dehydrogenase (LDH), catalase (CAT) and glutathione reductase (GR), were recorded. Data were analyzed by ANOVA, comparing the means by Tukey´s test (P<0.05). In the second experiment the potential of clove oil and sodium chloride (salt) added to water in mitigating the stress responses to simulated transporting was evaluated in 1.269 female juveniles. The experiment was conducted in a factorial design 3x3 (0, 3, 6 g.L-1 salt; 0, 5, 7.5 mg.L-1 clove oil) and data were submitted to ANOVA (p<0.05). In the first experiment, we observed glucose increase (53.9%) after anesthesia and/or stress. The stress increased cortisol levels (146.6%), lactate (294.6%) and lipid peroxidation in white muscle (45%) and decreased glycogen (40.1%). The hematocrit increased 7.9% after stress or anesthesia and the liver glycogen and HSI did not changed between treatments. Anesthesia or stress did not affect the LDH activity, but reduced the activity of CAT (46.1%) and GR (30.3%). In the second experiment a reduction of blood glucose was observed when the anesthetic was associated to salt (linear) or salt was associated to anesthetic (quadratic). The salt or anesthetic decreased the cortisol (linear) but did not affected hematocrit or hepatosomatic index. The salt increased glycogen in liver (linear) and white muscle (quadratic), but reduced the lactate (linear). Anesthesia increased the muscle glycogen (linear) and did not affect the lipid peroxidation that was increased (quadratic) by salt. The LDH activity was reduced (linear) by increasing concentrations of salt or its association with the anesthetic (quadratic). Clove oil decreased CAT activity (linear) and when associated to salt increased the GR activity. We concluded that air exposure and transporting are stressful situations that reduces welfare and meat quality and that clove oil (50 mg.L-1) mitigates the physiological responses to stress and does not cause lipid peroxidation but does not prevent this response resulting from air exposure. The clove oil and the salt (5 and 7.5 mg.L-1 and 3 to 6 gL-1, respectively), either in its isolated or combined form, are safe and effective in mitigating the stress effects of transporting in lambari.

La thèse a pour but d’élaborer et d’étudier les potentialités des semi-conducteurs organiques, transporteurs de trous (HTMs) pour l’application photovoltaïque à l’aide de cellules solaires à base de pérovskite (PSCs). Plusieurs familles de molécules HTM ont été préparées et déposées en solution pour l’élaboration des cellules solaires. L'objectif principal étant d'étudier et d’apporter des informations sur la relation entre la structure moléculaire des nouveaux matériaux de transport de trous et les performances photovoltaïques obtenues, cette étude contribue à une meilleure compréhension fondamentale des propriétés requises des matériaux de transport de trous pour de meilleures performances photovoltaïques.La première étude concerne l’élaboration d’une molécule de type p à base de thieno [3,2-b] thiophène comme élément central avec des dérivés de dimethoxytriphenylamine comme donneurs d’électrons aux extrémités. Différentes conformations sont proposées et révèlent des performances photovoltaïques significativement différentes dans les dispositifs PSC. Notons par exemple, qu’une conformation de structure planaire favorisent la conjugaison avec des valeurs élevées de mobilités et conductivités obtenues.Dans la seconde étude, des molécules donneur-accepteurs à base de dérivés d’acridone 9 (10H) comme accepteur ont été élaborés. En y associant différents fragments donneurs d'électrons, on obtient des structures présentant des caractéristiques favorables à la fois pour de bons transferts de charge intramoléculaire (ICT) et des niveaux d’énergie HOMO-LUMO adaptés et favorisant l’injection des trous de la pérovskite vers l’électrode métallique via le HTM. Des études similaires ont été effectuées avec la thioxanthone.A partir d’un précurseur bon marché et d’une préparation aisée, la troisième étude a permis de synthétiser un dérivé de 9,9’-biacridone, molécule push-pull de type p révélant une structure tridimensionnelle, similaire à celle du Spiro-OMeTAD, molécule référence pour les PSCs.Enfin, la dernière étude concerne l’élaboration de molécules donneur-accepteur à base de thiéno [3,4-c] pyrrole-4,6-dione (TPD). La motivation de cette partie est le développement de la molécule à structure planaire améliorant l’empilement π-π dans la fabrication de dispositifs sans joints de grains. Ces molécules possèdent également un fort caractère ICT, une conjugaison π étendue sur toute la structure et une bonne solubilité ce qui en fait un candidat HTM idéal pour la réalisation d’un dispositif PSCs sans dopant. / The aim of the thesis is to develop and study the potential of organic hole transporting materials (HTMs) for photovoltaic applications using perovskite-based solar cells (PSCs). Several families of HTM molecules have been prepared and deposited in solution for the fabrication of solar cells. Since the main objective is to study and provide information on the relationship between the molecular structure of new hole transport materials and the photovoltaic performances obtained, this study contributes to a better fundamental understanding of the required properties of hole transport materials for better photovoltaic performance.The first study concerns the development of p-type molecules based on Thieno [3,2-b] thiophene as a central unit and π-linker with dimethoxytriphenylamine as end-capping electron donors. Different configurations are designed and revealed significantly different photovoltaic performances in the PSC devices. Remarkable, a planar structure with linear conjugation shows higher values of mobility and conductivity than others, thus it improved device performances.In the second study, donor-acceptor molecules based on 9(10H)Acridone derivatives as an acceptor were developed. By incorporating different electron-donating fragments, we obtain structures with favorable characteristics for both good intramolecular charge transfer (ICT) character and adequate HOMO-LUMO energy levels. Their energy levels are suitable for collecting and injecting the holes from perovskite to the metal electrode through the HTM. Similar studies have been done with Thioxanthone.Using a cheap precursor and facile preparation, the third study synthesized a 9.9'-biacridone derivative. These p-type molecules possess a three-dimensional structure which is similar to that of Spiro-OMeTAD, state-of-the-art molecule for PSCs.Finally, the last study focus on the development of donor-acceptor molecules based on thieno [3,4-c] pyrrole-4,6-dione (TPD). The objective is elaboration of the planar structure molecule which could be improved the π-π stacking effect in the device fabrication without grain boundaries. These molecules also own a strong ICT character, an extended π-conjugation on the whole structure and a good solubility which makes it an ideal candidate for the dopant-free HTM in PSCs.

Solar energy is the foremost power source of our planet. Driving photosynthesis on our planet for 3 billion years the energy stored in the form of fossil fuels also originates from the sun. Consumption of fossil fuels to generate energy is accompanied with CO2 emission which affects the earth's climate in a serious manner. Therefore, alternative ways of converting energy have to be found. Solar cells convert sunlight directly into electricity and are therefore an important technology for future electricity generation. In this work solar cells based on the inorganic semiconductor titanium dioxide and hole-transporting dyes are investigated. These type of solar cells are categorized as hybrid solar cells and are conceptually related to both dye-sensitized solar cells and organic solar cells. Light absorption in the bulk of the hole-transporting dye layer leads to the formation of excitons that can be harvested at the organic/inorganic interface. Two design approaches were investigated: 1) utilizing a multilayer of a hole-transporting dye and 2) utilizing a hole-transporting dye as light harvesting antenna to another dye which is bound to the titanium dioxide surface.  Using a multiple dye layer in titanium dioxide/hole transporting dye devices, leads to an improved device performance as light harvested in the consecutive dye layers can contribute to the photocurrent. In devices using both an inteface-bound dye and a hole-transporting dye, excitation energy can be transferred from the hole-transporting dye to the interface dye.

Thesis (Ph. D.)--West Virginia University, 2002. / Title from document title page. Document formatted into pages; contains xiii, 134 p. : ill. (some col.). Vita. Includes abstract. Includes bibliographical references (p. 119-128).

Cerebral ischemia occurs when blood flow to the brain is insufficient to meet metabolic demand. This can result from cerebral artery occlusion that interrupts blood flow, limits CNS supply of oxygen and glucose, and causes an infarction/ischemic stroke. Ischemia initiates a cascade of molecular events in neurons and cerebrovascular endothelial cells including energy depletion, dissipation of ion gradients, calcium overload, excitotoxicity, oxidative stress, and accumulation of ions and fluid. Blood-brain barrier (BBB) disruption is associated with cerebral ischemia and leads to vasogenic edema, a primary cause of stroke-associated mortality. To date, only a single drug has received US Food and Drug Administration (FDA) approval for treatment of acute ischemia/reperfusion injury, recombinant tissue plasminogen activator (rt-PA). While rt-PA therapy restores perfusion to ischemic brain, considerable tissue damage occurs when cerebral blood flow is re-established. Therefore, there is a critical need for novel therapeutic approaches that can "rescue" salvageable brain tissue and/or protect BBB integrity during cerebral hypoxia and subsequent reoxygenation stress (H/R). One approach that may enable neural tissue rescue following H/R is CNS delivery of drugs with brain protective effects such as HMG-CoA reductase inhibitors (i.e., statins). Our present in vivo data demonstrates that atorvastatin, a commonly prescribed statin, attenuates poly (ADP-ribose) polymerase (PARP) cleavage in the brain following H/R, suggesting neuroprotective efficacy. However, atorvastatin use as a CNS therapeutic is limited by poor blood-brain barrier (BBB) penetration. Therefore, we examined regulation and functional expression of the known statin transporter Oatp1a4 at the BBB under H/R conditions. In rat brain microvessels H/R (6% O₂, 60 min followed by 21% O₂, 10 min) increased Oatp1a4 expression. Brain uptake of taurocholate (i.e., Oap1a4 probe substrate) and atorvastatin were reduced by Oatp inhibitors (i.e., estrone-3-sulfate, fexofenadine), suggesting involvement of Oatp1a4 in brain drug delivery. Pharmacological inhibition of TGF-β/ALK5 signaling with the selective inhibitor SB431542 increased Oatp1a4 functional expression, suggesting a role for TGF-β/ALK5 signaling in Oatp1a4 regulation. Taken together, our novel data show that targeting an endogenous BBB drug uptake transporter (i.e., Oatp1a4) may be a viable approach for optimizing CNS drug delivery for treatment of diseases with an H/R component.

The aims of the thesis were synthesis and studies of the properties of new solution processable electron-transporting and ambipolar donor-acceptor hybrids as well as the synthesis and investigation of the properties of dendritic charge-transporting materials possessing luminescence and redox characteristics. It is found that the newly synthesized solution processable bay carbazol-2-yl or -3-yl substituted perylene bisimides are applicable as ambipolar organic semiconductors with complementary charge-transporting properties. Bay triphenylamino substituted perylene bisimide is found to relevant for the fabrication of solution processable ambipolar organic field-effect transistor. Furthermore, electron-donor functionalized pyrene, triazine and triphenylamine core-centred organic materials exhibiting good luminescence, charge-transport and redox characteristics are appropriate for application in optoelectronic devices. / Disertacijos tikslas - naujų elektronus pernešančių ir bipolinių junginių skirtų organiniams lauko tranzistoriams sintezė ir savybių tyrimas. Taip pat dendritinių liuminescuojančių junginių, skirtų organiniams šviesos diodams, sintezė ir savybių tyrimas. Nustatyta, kad susintetinti nauji perilenbisimido dariniai su karbazol-2-il- ir karbazol-3-il pakaitais pasižymi ir teigiamų ir neigiamų krūvininkų pernašos savybėmis; pernašos efektyvumas priklauso nuo chromoforų sujungimo topologijos. Perilenbisimido darinys su trifenilamino pakaitais yra tinkamas naudoti bipoliniuse organiniuose lauko tranzistoriuose, kurių sluoksniai gaunami, liejant tirpalus. Taip pat elektronų donorinėmis grupėmis funkcionalizuoti, pireno, triazino ir trifenilamino šerdis turintys junginiai, pasižymintys liuminescensija, krūvininkų pernaša ir gali būti panaudoti organiniuose šviesos dioduose.

Thesis (Ph. D.)--University of Texas Southwestern Medical Center at Dallas, 2008. / Vita. Includes bibliographical references (p. 95-106).