In the future, the 25 as internal loop region of Pro-RIP can be modified for the optimized recognition of proteases of other HIV strains. This approach opens a new opportunity for the anti-HIV application of maize RIP and other related type III RIPs. A modified maize RIP may also be applied to target other viruses and pathogens, for examples, hepatitis C and malaria, which are dependent on pathogen-encoded proteases for replication. / In this study, we provide an account on the generation of HIV-1 protease-sensitive maize RIP variants by first incorporating the HIV-1 protease recognition sequences to the internal inactivation region of the Pro-RIP. Among the five variants, three variants were cleaved and activated by HIV-1 protease in vitro and in vivo, resulting in an active two-chain form with N-glycosidase activity comparable to the fully active maize RIP. In addition, the variants inhibited viral replication in human T lymphocytes (C8166) infected by two T-tropic HIV-1 strains, HIV-1IIIB and HIV-1 RF/V82F/I84V, and their cytotoxicity towards uninfected cells was similar to the non-activated precursor (TAT-Pro). In comparison to TAT-Pro, variants TAT-Pro-HIV-MA/CA and Pro-TAT-Pro-HIV-p2/NC had 2- to 70-fold increase in the inhibition of p24 antigen production in the HIV-infected cells with low cytotoxicity towards uninfected C8166 cells. / Maize RIP is classified as a type III RIP. It is synthesized in the endosperm of maize as an inactive precursor (Pro-RIP), which contains a 25-amino acid internal inactivation region. During germination, a two-chain activated form (MOD) is generated by endogenous proteolysis of the internal inactivation region, whereas the two chains (16.5 and 8.5 kDa) are tightly associated without disulfide linkage. Our group has solved the crystal structures of both the Pro-RIP and MOD and found that this internal inactivation region is on the surface of the N-terminal domain in Pro-RIP . The removal of this internal inactivation region increases the inhibition of protein synthesis of rabbit reticulocyte lysate by over 600 folds. The presence of the internal inactivation region has led us to derive a novel strategy to enhance the specificity of maize RIP towards HIV-infected cells while minimizing its cytotoxic effect on normal cells. / Ribosome-inactivating proteins (RIPs) are RNA N-glycosidases which cleave the N-glycosidic bond of adenine-4324 at the alpha-sarcin/ricin (SR) loop of 28S rRNA. The depurination of the SR loop results in the inhibition of protein synthesis by impairing the binding of EF-1 or EF-2 to ribosomes. RIPs are therefore highly cytotoxic and have been used as abortificiant, anti-cancer and anti-HIV agents, either alone or as a component of immunotoxins. Many type I and II RIPs, such as MAP30, GAP30, DAP30, pokeweed antiviral protein (PAP) and ricin, have been reported to possess anti-HIV activity by inhibiting viral replication in vitro and in vivo though the anti-HIV mechanism is still unclear. / Law, Ka Yee. / Adviser: Pang-Chui Shaw. / Source: Dissertation Abstracts International, Volume: 72-04, Section: B, page: . / Thesis (Ph.D.)--Chinese University of Hong Kong, 2010. / Includes bibliographical references (leaves 124-144). / Electronic reproduction. Hong Kong : Chinese University of Hong Kong, [2012] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Electronic reproduction. Ann Arbor, MI : ProQuest Information and Learning Company, [200-] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Abstract also in Chinese.

Diss. (sammanfattning) Stockholm : Karolinska institutet, 2006. / Härtill 4 uppsatser.

Diss. (sammanfattning) Stockholm : Karol. inst., 2003. / Härtill 5 uppsatser.

Diss. (sammanfattning) Stockholm : Karol. inst., 2003. / Härtill 5 uppsatser.

Thesis (D.P.H.)--University of Alabama at Birmingham, 2008. / Title from first page of PDF file (viewed on June 25, 2009). Includes bibliographical references.

Dissertation (Ph.D.) -- University of Texas Southwestern Medical Center at Dallas, 2008. / Vita. Bibliography: p.99-110

Submitted by Fabio Sobreira Campos da Costa (fabio.sobreira@ufpe.br) on 2017-03-07T12:59:54Z No. of bitstreams: 2 license_rdf: 1232 bytes, checksum: 66e71c371cc565284e70f40736c94386 (MD5) DISSERTAÇÃO- CINDY SIQUEIRA BRITTO AGUILERA.pdf: 2705379 bytes, checksum: 97ce59193eca13b16910a462fb383f9b (MD5) / Made available in DSpace on 2017-03-07T12:59:54Z (GMT). No. of bitstreams: 2 license_rdf: 1232 bytes, checksum: 66e71c371cc565284e70f40736c94386 (MD5) DISSERTAÇÃO- CINDY SIQUEIRA BRITTO AGUILERA.pdf: 2705379 bytes, checksum: 97ce59193eca13b16910a462fb383f9b (MD5) Previous issue date: 2016-07-29 / CAPES / Os hidróxidos duplos lamelares (HDL) vêm recebendo grande atenção no desenvolvimento de sistemas de liberação de fármacos, devido à capacidade que esses sólidos inorgânicos apresentam, de intercalar na sua região interlamelar, ou adsorver em sua vasta área superficial, substâncias biologicamente ativas. Os HDL podem ser sintetizados em laboratório por rotas simples e de baixo custo, que permitem o isolamento de sólidos de alta pureza. O antirretroviral zidovudina (AZT) apresenta, como principal limitação, o baixo tempo de meia vida plasmática, sendo necessária a administração de várias doses diárias, e assim favorecendo o surgimento de reações adversas. Nesse contexto, o presente trabalho teve como objetivo o desenvolvimento de sistema de liberação prolongada para o fármaco AZT, utilizando o HDL como carreador. Para isso, foi realizado, a síntese e caracterização de MgAlCl-HDL, e obtenção de sistemas HDL:AZT, através da síntese direta por copreciptação, realizando variações na concentração de AZT no meio reacional e no tempo de agitação durante a síntese. Os materiais obtidos foram caracterizados pelas técnicas de difração de raios-X (DRX), termogravimetria (TG), análise térmica diferencial (DTA), espectroscopia no infravermelho (IV), microscopia eletrônica de varredura (MEV), análises de tamanho de partícula, porosidade e área superficial, além da análise elementar de metais e de carbono, hidrogênio e nitrogênio (CHN). Entre os sistemas HDL:AZT, o obtido com proporção molar 1:1 (Al+3/AZT) no meio reacional e 1 hora de agitação, apresentou o melhor perfil de liberação prolongada do fármaco, alcançando 90% de liberação do AZT em 24 horas de estudo. O MgAl-ClHDL demonstrou ser um carreador biocompatível, além de proporcionar uma diminuição na citotoxicidade do AZT frente a linhagem de macrófagos humanos. Desta forma, o sistema de liberação prolongada obtido, para o fármaco AZT, poderá ser utilizado em formulações farmacêuticas, no intuito de otimizar a terapia antirretroviral atual. / Layered double hydroxides (LDH) have received great attention in the development of drug delivery systems because of the ability these inorganic solids present to intercalate in its interlayer region, or adsorb on its vast surface area, biologically active substances. The LDH can be synthesized in the laboratory by simple and low-cost routes that generate high-purity solids. The antiretroviral zidovudine (AZT) has as its main limitation, low plasma half-life, requiring the administration of multiple daily doses, and thus favoring the appearance of side effects. In this context, the present study aimed to develop sustained release systems for the AZT using LDH as a drug carrier. In order to accomplish this goal, it was carried out the synthesis and characterization of the MgAl-Cl-LDH and obtained the systems LDH:AZT by coprecipitation, with variations of AZT concentration in the reactional medium and stirring time during synthesis. The materials were characterized by the following techniques: X-ray diffraction (XRD), Thermogravimetry (TG), Differential Thermal Analysis (DTA), Infrared Spectroscopy (IR), Scanning Electron Microscopy (SEM), Particle Size Analysis, Porosity and Surface Area, and Elemental Analysis of Metals and Carbon, Hydrogen and Nitrogen (CHN). Among the LDH:AZT systems, the one with molar ratio 1:1 (Al+3/AZT) in the reaction medium and one hour of stirring presented the best sustained drug release profile, reaching the amount of 90% of AZT released within 24 hours of study. The MgAl-Cl-LDH showed to be a biocompatible drug carrier, in addition to providing a decrease in cytotoxicity of AZT against human macrophage lineage cells. Therefore, the sustained release system obtained to AZT may be used in pharmaceutical formulations in order to optimize the current antiretroviral therapy.

As the first structural example of this class of proteins, crystals of Pro-RIP and MOD were grown and diffracted to 2.4 and 2.5 A respectively. The structures of the two proteins are solved and found to be highly similar, with main chain RMSD of 0.519. Each protein has two domains. The N-terminal domain consists of five alpha-helices and five-stranded mixed beta-sheet. The conserved active site residues Y94, Y130, E207, R210 and W241, similar to those of other RIPs, are located at the cleft between the N-terminal and C-terminal domains. In Pro-RIP, the 25-amino acid internal inactivation region is found on the surface of the N-terminal domain and consists of a flexible loop followed by a long alpha-helix. Like bacterial ribosome-inactivating proteins, maize ribosome-inactivating protein does not have a back-up glutamate in the active site, which helps the protein to retain some activity if the catalytic glutamate is mutated. The structure of maize RIP reveals that the active site is too small to accommodate two glutamate residues and suggests that maize ribosome-inactivating protein may represent an intermediate product in the evolution of ribosome-inactivating proteins. / Pull-down assay indicated that the internal inactivation region diminished the interaction of Pro-RIP with purified ribosomes and ribosomal proteins P0, P1 and P2. Surface plasmon resonance assays showed that Pro-RIP has a slower association rate and faster dissociation rate on intact ribosomes when compared to MOD, resulting 80-fold decrease in binding affinity. These evidences strongly suggested that the reduced ribosome-inactivating activity and cytotoxicity of Pro-RIP is the result of its diminished interaction with the ribosomes. The ribosome binding site of MOD is found to be different from TCS and saporin, which are located between the anti-parallel beta-sheet in the C-terminal domain. In MOD, the positive-charged residues K158, K159, K160 and K161 that were found to be important for ribosome binding are located in the N-terminal domain, underneath the internal inactivation region. / Ribosome-inactivating proteins (RIPs) are rRNA N-glycosidases, which hydrolyze the N-glycosidic bond of A-4324 in 28S rRNA of eukaryotic ribosomes. Based on the number of subunits, RIPs are grouped into three classes. Type I RIPs (e.g. trichosanthin and saporin) are monomeric polypeptide with molecular weights of 25-32 kDa. Type II RIPs (e.g. ricin and cinnamomin) are heterodimeric proteins whose subunits are linked by a disulphide bridge, with molecular weights of 60-65 kDa. Chain A of type II RIPs is the catalytic subunit, while chain B is the lectin subunit, which facilitates the cellular entry of the protein by interacting with carbohydrates on the cell surface. Maize ribosome-inactivating protein is classified as a type III RIP, or an atypical RNA N-glycosidase. It is synthesized and stored in the kernel as a 34 kDa inactive precursor (Pro-RIP). During germination, the precursor undergoes proteolysis to generate a two-chain active RIP (MOD). Previous study has found that the 25-amino acid residues at the acidic internal inactivation region, which are removed during activation of Pro-RIP, is the major control element to suppress its in vitro protein synthesis inhibition activity. / Since the internal inactivation region of Pro-RIP controls the ribosome-inactivating activity and cytotoxicity, it provides an opportunity to engineer an on/off switch forits activity by HIV-1 protease through engineering HIV-1 protease recognition sites into the internal inactivation region of Pro-RIP. A variant that contains two HIV-1 protease recognition sites incorporated to the 25-amino acid internal inactivation region was found to be activated by HIV-1 protease in vitro. This variant entered cells more efficiently than Pro-RIP and was as cytotoxic as MOD. This switch may be applied to other RIPs such as ricin A chain and other protease recognition sequences may be used for increasing the specificity of an RIP toward viral infected cells. / The internal inactivation region of Pro-RIP greatly decreases its cytotoxicity, but not cellular uptake through alpha-2 macroglobulin receptor. On the contrary, the acidic residues within the region hinder fluid-phase endocytosis. Moreover, it is found that the internal inactivation region does not affect sub-cellular localization of the protein - MOD and Pro-RIP locate in the same cellular compartment (nucleus in JAR or cytoplasm in J774A.1 and C8166). / Mak, Nga Sze Amanda. / "July 2007." / Adviser: Shaw Pang Chui. / Source: Dissertation Abstracts International, Volume: 73-03, Section: B, page: . / Thesis (Ph.D.)--Chinese University of Hong Kong, 2009. / Includes bibliographical references (leaves 216-236). / Electronic reproduction. Hong Kong : Chinese University of Hong Kong, [2012] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Electronic reproduction. [Ann Arbor, MI] : ProQuest Information and Learning, [201-] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Abstract also in Chinese.

Ribosome-inactivating proteins (RIPs) are cytotoxins that remove a specific adenine from the sarcin-ricin loop (SRL) of large ribosomal RNA and in turn inhibit protein synthesis. Apart from N-glycosidase activity, some RIPs are found to possess antiviral activity and the suppression on human immunodeficiency virus (HIV) has been extensively studied. / Maize RIP stands out from other members for having an internal inactivation region and requires proteolytic removal to regain full activity. We have exploited the innate regulatory mechanism of maize RIP and increased its specificity towards HIV by adding the HIV protease recognition site to the inhibitory segment. Our results demonstrated the wild-type maize RIP is inhibitory on simian immunodeficiency virus (SIV) replication in rhesus macaque and showed the HIV sensitive variant undergoes specific proteolytic activation upon viral infection and exerts enhanced in vitro antiviral effects. Therapeutic applications of RIPs are often restricted by short in vivo half-life and strong allergic responses and we attempted to improve the therapeutic potential of maize RIP by coupling with polyethylene glycol (PEG). Two mutants were generated for PEGylation and the resultant MOD-PEG₂₀ₖ variant was shown to be less sensitive to antibody recognition and has a prolonged plasma half-life, suggesting it may have enhanced therapeutic values. Besides, the applicability of protease-activation system in RIPs without inactivation loop was tested using ricin A chain (RTA) as the test case and HIV recognition sites were introduced either within or at C-terminus of the protein. The C-terminal RTA variants were specifically processed and had the anti-HIV activity increased in HIV-infected cells. / The present work illustrates the potential development of maize RIP as an anti-HIV agent and shows PEGylation can serve to enhance the protein for in vivo applications. Besides, the engineering of RTA with HIV recognition site suggests the potential of the protease-activation strategy to other RIPs for activity control. / 核糖體失活蛋白（RIPs）是一種細胞毒素蛋白，能特異地水解核糖體sarcin-ricin環（SRL），通過脫嘌呤抑制核糖體的蛋白合成功能。除此功能以外，很多RIP還具有抗病毒的活性，如抗人免疫缺陷病毒（HIV）的活性。 / 玉米RIP與其他的RIP不同，它含有一段內部失活結構域，需通過蛋白水解作用移除該結構域才能成為活性體。我們利用玉米RIP的這一特性，通過對內部結構域的改造，獲得了兩個可被HIV蛋白酶特異識別的突變體。體外實驗証明HIV可以特異地識別突變體上的蛋白酶切割位點，從而將其啟動產生抗病毒活性。另外，我們以蓖麻毒素A鏈（RTA）為例，分別於蛋白質的內部和碳端插入HIV識別序列，驗證了蛋白酶啟動系統在沒有內部失活結構域的RIP中，也能通過HIV蛋白酶的切割而活化並取得抗病毒活性。我們還揭示玉米RIP活性體可以有效抑制猿免疫缺陷病毒（SIV）在感染恒河猴體內的複制。此外，我們嘗試通過與聚乙二醇（PEG）融合來優化玉米RIP的免疫原性和半衰期，成功製備了兩種融合突變體，MOD-PEG₂₀ₖ顯示較不容易被抗體識別且延長了血液半衰期。 / 綜上所述，我們的研究表明玉米RIP作為抗HIV抑制劑具有良好的研發前景，而RTA的改造展示蛋白酶啟動系統可應用於其他RIP，同時我們還證明了PEG修飾可以很好的應用於蛋白類藥物的研發。 / Au, Ka Yee. / Thesis M.Phil. Chinese University of Hong Kong 2014. / Includes bibliographical references (leaves 84-95). / Abstracts also in Chinese. / Title from PDF title page (viewed on 17, October, 2016). / Detailed summary in vernacular field only. / Detailed summary in vernacular field only. / Detailed summary in vernacular field only.

CoordenaÃÃo de AperfeiÃoamento de Pessoal de NÃvel Superior / A Aids à um grave problema de saÃde pÃblica, associado os altos Ãndices de mortalidade em muitas regiÃes do Mundo. A epidemia tem sido e continuarà a ser um dos principais desafios para a saÃde pÃblica mundial nas prÃximas dÃcadas. O acesso das pessoas vivendo com HIV/Aids a uma assistÃncia farmacÃutica de qualidade representa um dos maiores desafios para os sistemas de saÃde, principalmente nos paÃses subdesenvolvidos. Um dos desafios para saÃde pÃblica no Brasil, alÃm da prevenÃÃo, à garantir a qualidade no atendimento e tratamento das pessoas que vivem com HIV/Aids. A nÃo-adesÃo aos novos medicamentos para Aids à considerada como um dos mais ameaÃadores perigos para a efetividade do tratamento, no plano individual, e para a disseminaÃÃo de vÃrus-resistÃncia, no plano coletivo. Os novos regimes terapÃuticos parecem exigir do indivÃduo que adere ao tratamento integraÃÃo complexa entre conhecimentos, habilidades e aceitaÃÃo, alÃm de outros importantes fatores ligados ao ambiente e ao cuidado à saÃde. Apresentamos neste trabalho um estudo estatÃstico sobre a adesÃo dos pacientes ao tratamento anti-HIV com entrevistas realizadas com 206 pacientes no Centro de Especialidades MÃdicas de Aracaju, na cidade de Aracaju, Sergipe. CaracterÃsticas sÃcio-demogrÃficas foram coletadas, bem como variÃveis que caracterizam a nÃo-adesÃo ao tratamento. A medida de adesÃo foi auto-relato (formulÃrio de entrevista), podendo ser definida a partir do critÃrio de trÃs autores: Jordan (2000), Morinsky-Green (1986) e Haynes-Sackett (1981). As variÃveis de nÃo-adesÃo foram correlacionadas entre si e com outras variÃveis a partir do cÃlculo de probabilidades e do Coeficiente de Yule. Os sujeitos do estudo mostraram caracterÃsticas sÃcio-demogrÃficas (baixa renda e gÃnero) semelhantes a atual tendÃncia da epidemia de Aids no Brasil. As variÃveis associadas com maior risco para a nÃo-adesÃo foram: GÃnero, RaÃa, Uso de Drogas ilÃcitas e o tempo de tratamento. EstratÃgias de intervenÃÃo devem ser desenvolvidas antes mesmo do inÃcio da terapia antiretroviral. Devem tambÃm ser adotados indicadores para o acompanhamento da adesÃo pela equipe de saÃde. Isto poderà ajudar a prevenir ou minimizar a ocorrÃncia futura de resistÃncia de medicamentos ao HIV, ter melhores resultados ao tratamento, bem como a reduÃÃo de gastos governamentais. A adoÃÃo desses indicadores deve ser um dos principais objetos de programas com distribuiÃÃo universal de ARV como à o caso do Brasil. / AIDS is a serious public health problem, associated with high mortality rates in many regions of the world. The epidemic has been and remains a major challenge to global public health in the coming decades. The access of people living with HIV / AIDS to pharmaceutical care quality is one of the greatest challenges to health systems, especially in underdeveloped countries. One of the challenges for public health in Brazil, in addition to prevention, is to ensure quality care and treatment of people living with HIV / AIDS Non-adherence to new medicines for AIDS is regarded as one of the most threatening dangers to the effectiveness of treatment for the individual, and the spread of virus-resistance, as a team. The new regimens seem to require the individual to comply with treatment complex integration of knowledge, skills, and acceptance, and other important factors related to environment and health care. Here we present a statistical study of patient adherence to HIV treatment based on interviews with 206 patients at the Center for Medical Specialties in Aracaju, in the city of Aracaju, Sergipe. Socio-demographic data were collected, as well as variables that characterize the non-compliance. The measure of adherence was self-report (interview form) and can be defined from the criterion of three authors: Jordan (2000), Morinsky-Green (1986) and Haynes-Sackett (1981). The variables of noncompliance were correlated with each other and with other variables from the probability calculation and the coefficient of Yule. The study subjects showed socio-demographic (low income and gender) like the current trend of AIDS epidemic in Brazil. Variables associated with increased risk for non-compliance were: Gender, Race, Illicit Drug Use and treatment time. Intervention strategies must be developed before the start of antiretroviral therapy. Should also be adopted indicators for monitoring the adherence by the health service. This may help prevent or minimize future occurrence of drug resistance to HIV have better treatment outcomes and reducing government spending. The adoption of these indicators should be one of the main objects of programs with universal distribution of antiretroviral as is the case of Brazil.