Cystic echinococcosis in southern Brazil

Cystic echinococcosis (CE) is very common in the southern part of Rio Grande do Sul State where sheep and cattle raising is the most important economical activity. Prevalence in intermediate hosts is well known due to reports in slaughterhouses while human reports are of discussed value. This is due to underreporting of cases and few epidemiological studies make it difficult to assess the situation of echinococcosis in the population. Whereas cattle infection rate is more or less stable around 12% of the slaughter animals, in sheep there has been an increasing number in the last five years. Some efforts have been done to control the zoonosis but no effective results were obtained so far. Probably educational efforts to change human practices (feeding dogs with raw viscera), periodic treatment of dogs with praziquantel and joined actions with slaughterhouses could bring more attention to improve some control measures.

Diversidade genética e resistência natural ao Maraviroc em estirpes do vírus da imunodeficiência humana Tipo 1 (HIV-1) em circulação em utilizadores de drogas por via endovenosa na Grande Lisboa

RESUMO: O maraviroc (MVC) é o único anti-retroviral antagonista do co-receptor CCR5 licenciado e interage com as ansas transmembranares de CCR5, induzindo uma alteração da sua conformação e impedindo a interacção com gp120. O MVC é activo apenas contra estirpes R5 de HIV-1, sendo utilizado em terapia de recurso. Neste trabalho, foi estudada a diversidade genética da região C2V3C3 do gene env de estirpes de HIV-1 de oxicodependentes por via endovenosa da Grande Lisboa, pesquisando-se também a presença de polimorfismos genéticos naturais. Foram utilizadas 52 amostras de plasma e para 35 destas foi amplificado por RT-nested PCR um produto de 565 pb. A análise filogenética revelou a seguinte distribuição de genótipos: 23 B (incluindo, provavelmente, 2 CRF14_BG), 8 A, 3 G e 1 F1. Após tradução, e por comparação com a sequência consenso B, verificou-se uma elevada frequência de polimorfismos genéticos, sendo encontradas algumas “assinaturas de aminoácidos” relativas aos subtipos não-B. Realizou-se ainda uma pesquisa de locais de N-glicosilação e a previsão da utilização de co-receptores (abordagem genotípica), com recurso às regras 11/25 e da carga líquida da ansa V3 e aos programas PSSM e geno2pheno[coreceptor]. Observou-se uma conservação genérica do número de locais de N-glicosilação e foram identificadas 5 sequências com tropismo X4 ou duplo. Por fim, com base na literatura, realizou-se uma pesquisa de polimorfismos genéticos associados a resistência ao MVC presentes na ansa V3. Foi observado um número elevado destas mutações. A presença dos padrões 11S+26V e 20F+25D+26V, num total de 3 sequências, é relevante, visto estes estarem inequivocamente associados à resistência in vivo ao MVC. Apesar de não estar ainda definido um perfil de resistência para o MVC, a presença das mutações encontradas, em indivíduos sem contacto prévio com o fármaco, trará implicações relevantes na sua gestão clínica, considerando a introdução do MVC na terapia de recurso.---------- ABSTRACT: Maraviroc (MVC) is the only CCR5 inhibitor licensed today. This drug interacts with the transmembrane helices of CCR5 co-receptor, inducing a conformation change of its extracellular loops and preventing the interaction with gp120. MVC is only active against R5 strains of HIV-1 and is currently used in salvage therapy. The genetic diversity of the env C2V3C3 region of HIV-1 strains from injecting drug users in the Greater Lisbon was studied, along with the presence of natural genetic polymorphisms. 52 plasma samples were used and the amplification by RT-nested PCR of a 565 bp-product was possible in 35 of them. The phylogenetic analysis revealed 23 sequences classified as subtype B (probably including 2 CRF14_BG), 8 A, 3 G and 1 F1. After translation, the presence of natural genetic polymorphisms was studied by comparison to a subtype B consensus. A high frequency of genetic polymorphisms was observed and significant “amino acid signatures” were found in association with non-B subtypes. A full characterization of the N-glycosylation sites was also performed and a coreceptor prediction (genotypic approach) was accomplished using the 11/25 and the V3 net charge rules and the programs PSSM and geno2pheno[coreceptor]. The number of N-glycosylation sites was generically preserved. Five sequences were defined as X4 or dual-tropic. Based on published data, a search for genetic polymorphisms, present in V3loop, associated to MVC resistance was finally undertaken. Several of such mutations were observed, being particularly interesting the presence of the patterns 11S+26V and 20F+25D+26V, in a total of 3 sequences, since these patterns have unequivocally been associated with MVC resistance in vivo. Although a resistance profile for MVC is not yet defined, the presence of these mutations in MVC-naïve populations may have significant impact in their clinical management in the future, especially considering the introduction of this drug in salvage therapy.

Divertículos da uretra feminina: uma revisão contemporânea

Introduc¸ão: Os divertículos uretrais femininos (DUF) afetam de 0,6 a 4,7% das mulheres, causam frequentemente sintomas urinários persistentes e podem associar-se a complicac¸ões como litíase e transformac¸ão maligna. Existe ainda elevado subdiagnóstico de DUF, bem como atraso diagnóstico e terapêutico. O objetivo deste trabalho é analisar o estado de arte em relac¸ão à etiologia, diagnóstico e terapêutica desta patologia. Materiais e métodos: Revisão bibliográfica de artigos obtidos até janeiro/2014 na base de dados Medline utilizando as palavras-chave: «female urethral diverticula», «female urethral diverticulum», «urethral diverticula», «urethral diverticulum» e «female urethra»; e após pesquisa de referências bibliográficas relevantes nos artigos obtidos. Resultados: A maioria dos DUF parecem surgir secundariamente à infec¸ão das glândulas periuretrais e uretrais. Apesar da associac¸ão clássica à tríade de disúria, dispareunia e gotejo pós-miccional, as manifestac¸ões clínicas são diversas e inespecíficas. Mais de um terc¸o são palpáveis ao exame ginecológico. Os métodos imagiológicos disponíveis, nomeadamente a ressonância magnética e a ecografia, apresentam elevada capacidade diagnóstica e contribuem para o planeamento cirúrgico. Dependendo da localizac¸ão, conformac¸ão e sintomatologia associada, a terapêutica dos DUF poderá ser conservadora ou, na maioria dos casos, cirúrgica. Discussão: A avaliac¸ão clínica permanece essencial para o diagnóstico de DUF. A ressonância magnética é a modalidade com maior taxa de diagnóstico e de exclusão de complicac¸ões pré ou pós-operatórias. Foram descritas técnicas menos invasivas, porém a diverticulectomia uretral transvaginal permanece a terapêutica com maior cura sintomática. Conclusão: A sensibilizac¸ão da comunidade médica é a melhor arma no combate ao subdiagnóstico e atraso diagnóstico dos DUF.

Artefacts induced on c-type haem proteins by electrode surfaces

J Biol Inorg Chem (2011) 16:209–215 DOI 10.1007/s00775-010-0717-z

Molecular determinants of ligand specificity in carbohydrate-binding modules: an NMR and X-ray crystallography integrated study

Dissertação para obtenção do Grau de Doutor em Bioquímica – Ramo Bioquímica Estrutural

Helminthiases in Montes Claros. Preliminary survey

A preliminary survey was conducted for the presence of helminths in the city of Montes Claros, M. G., Brazil. Three groups of persons were examined by the direct smear, Kato thick film and MIFC techniques; one group by direct smear and Kato only. General findings were: a high prevalence of hookworm, followed by ascariasis, S. mansoni, S. stercoralis and very light infections with T. trichiurá. E. vermicularis and H. nana were ranking parasites at an orphanage, with some hookworm and S. mansoni infections as well. At a pig slaughter house, the dominant parasites were hookworm and S. mansoni. Pig cysticercosis was an incidental finding worth mentioning for the health hazard it represents for humans as well as an economic loss. From the comparative results between the Kato and the MIF the former proved itself again as a more sensitive and reliable concentration method for helminth eggs, of low cost and easy performance.

Novel FGFR1 Mutations in Kallmann Syndrome and Normosmic Idiopathic Hypogonadotropic Hypogonadism: Evidence for the Involvement of an Alternatively Spliced Isoform

OBJECTIVE: To determine the prevalence of fibroblast growth factor receptor 1 (FGFR1) mutations and their predicted functional consequences in patients with idiopathic hypogonadotropic hypogonadism (IHH). DESIGN: Cross-sectional study. SETTING: Multicentric. PATIENT(S): Fifty unrelated patients with IHH (21 with Kallmann syndrome and 29 with normosmic IHH). INTERVENTION(S): None. MAIN OUTCOME MEASURE(S): Patients were screened for mutations in FGFR1. The functional consequences of mutations were predicted by in silico structural and conservation analysis. RESULT(S): Heterozygous FGFR1 mutations were identified in six (12%) kindreds. These consisted of frameshift mutations (p.Pro33-Alafs*17 and p.Tyr654*) and missense mutations in the signal peptide (p.Trp4Cys), in the D1 extracellular domain (p.Ser96Cys) and in the cytoplasmic tyrosine kinase domain (p.Met719Val). A missense mutation was identified in the alternatively spliced exon 8A (p.Ala353Thr) that exclusively affects the D3 extracellular domain of FGFR1 isoform IIIb. Structure-based and sequence-based prediction methods and the absence of these variants in 200 normal controls were all consistent with a critical role for the mutations in the activity of the receptor. Oligogenic inheritance (FGFR1/CHD7/PROKR2) was found in one patient. CONCLUSION(S): Two FGFR1 isoforms, IIIb and IIIc, result from alternative splicing of exons 8A and 8B, respectively. Loss-of-function of isoform IIIc is a cause of IHH, whereas isoform IIIb is thought to be redundant. Ours is the first report of normosmic IHH associated with a mutation in the alternatively spliced exon 8A and suggests that this disorder can be caused by defects in either of the two alternatively spliced FGFR1 isoforms.

Pig bite in Brazil: a case series from a teaching hospital

A retrospective survey done from 1987 till 1990 revealed that 23 patients bitten by pigs sought medical help at a teaching hospital in Uberlândia, in southeastern Brazil. Most cases (21) were from Uberlândia. The cases were evenly distributed by month and by year; most of them (14/16; 87.5%) occurred between 7. OOa.m. and 7.00 p. m. The male to female ratio was 6.7:1. Age ranged from 6 to 73 (mean 38.95 ± SD 22.06, median 36). The bites were more common on the upper limbs, particularly on the forearms. In 11(47.8%) cases the injury was described as deep. In most cases where information was available the injury was related to capture, transport or immobilisation ofthe pigfor slaughter. The following medical procedures were performed: local cleansing in 19(82.6%) cases, rabies vaccine (12; 52.2%), antirabies serum (2; 8.7%), suturing (6; 26.1%) and tetanus vaccine (12; 52.2%). There was no case of infection at the bite site, neither of rabies or tetanus. By our data, the annual incidence of pig bite in Uberlândia can be estimated to be about 1.5/100.000.

Functional and structural studies of two enzymes: membrane bound kinase and Z-DNA/Z-RNA-binding protein

Dissertação para obtenção do Grau de Doutor em Sistemas de Bioengenharia

Efeito da idade ao abate e uso de suplementação sobre a relação de ácidos graxos da carne de cordeiros da raça Morada Nova.

Resumo: Objetivou-se avaliar o efeito da idade ao abate e do uso ou não de suplementação na fase de cria sobre as relações de ácidos graxos da carne de ovinos. Foram utilizados 32 cordeiros Morada Nova, machos, não castrados, abatidos aos 60, 78, 106 e 134 dias, em grupos de 8 cordeiros por abate. Na carne avaliada foram identificados sete ácidos graxos saturados, cinco ácidos graxos monoinsaturados e cinco ácidos graxos poli-insaturados. O uso da suplementação na fase de cria (com Creep feeding) não alterou as relações entre ácidos graxos saturados e insaturados, bem como o percentual de ácidos graxos desejáveis (P>0,05) presentes na carne de cordeiros. A idade ao abate interferiu positiva e linearmente na relação entre ácidos graxos monoinsaturados e insaturados, o que permite abater os cordeiros com até 134 dias sem prejuízo para as relações entre os ácidos graxos [Effect of age at slaughter and use of supplementation on the ratio of fatty acids of meat from lambs of Morada Nova race]. Abstract: This study aimed to evaluate the effect of age at slaughter and the use or not supplementation in creating phase on the relationship of fatty acids of sheep meat. 32 Morada Nova lambs were used, male, not castrated, slaughtered at 60, 78, 106 and 134 days, 8 lambs for slaughter groups. In evaluated meat were identified seven saturated fatty acids, monounsaturated fatty acids and five polyunsaturated fatty acids. The use of supplementation in the creation phase (with Creep feeding) did not alter the relationship between saturated and unsaturated fatty acids, as well as the percentage of desirable fatty acids (P>0,05) in the lamb meat. The age at slaughter interfered positively and linearly in the relationship between monounsaturated and unsaturated fatty acids, which allows slaughter lambs up to 134 days without prejudice to the relationship between fatty acids

Application of NMR RDC’s, relaxation and self-diffusion for the study of dynamic processes of small molecules in solution

Spin-lattice Relaxation, self-Diffusion coefficients and Residual Dipolar Couplings (RDC’s) are the basis of well established Nuclear Magnetic Resonance techniques for the physicochemical study of small molecules (typically organic compounds and natural products with MW < 1000 Da), as they proved to be a powerful and complementary source of information about structural dynamic processes in solution. The work developed in this thesis consists in the application of the earlier-mentioned NMR techniques to explore, analyze and systematize patterns of the molecular dynamic behavior of selected small molecules in particular experimental conditions. Two systems were chosen to investigate molecular dynamic behavior by these techniques: the dynamics of ion-pair formation and ion interaction in ionic liquids (IL) and the dynamics of molecular reorientation when molecules are placed in oriented phases (alignment media). The application of NMR spin-lattice relaxation and self-diffusion measurements was applied to study the rotational and translational molecular dynamics of the IL: 1-butyl-3-methylimidazolium tetrafluoroborate [BMIM][BF4]. The study of the cation-anion dynamics in neat and IL-water mixtures was systematically investigated by a combination of multinuclear NMR relaxation techniques with diffusion data (using by H1, C13 and F19 NMR spectroscopy). Spin-lattice relaxation time (T1), self-diffusion coefficients and nuclear Overhauser effect experiments were combined to determine the conditions that favor the formation of long lived [BMIM][BF4] ion-pairs in water. For this purpose and using the self-diffusion coefficients of cation and anion as a probe, different IL-water compositions were screened (from neat IL to infinite dilution) to find the conditions where both cation and anion present equal diffusion coefficients (8% water fraction at 25 ºC). This condition as well as the neat IL and the infinite dilution were then further studied by 13C NMR relaxation in order to determine correlation times (c) for the molecular reorientational motion using a mathematical iterative procedure and experimental data obtained in a temperature range between 273 and 353 K. The behavior of self-diffusion and relaxation data obtained in our experiments point at the combining parameters of molar fraction 8 % and temperature 298 K as the most favorable condition for the formation of long lived ion-pairs. When molecules are subjected to soft anisotropic motion by being placed in some special media, Residual Dipolar Couplings (RDCs), can be measured, because of the partial alignment induced by this media. RDCs are emerging as a powerful routine tool employed in conformational analysis, as it complements and even outperforms the approaches based on the classical NMR NOE or J3 couplings. In this work, three different alignment media have been characterized and evaluated in terms of integrity using 2H and 1H 1D-NMR spectroscopy, namely the stretched and compressed gel PMMA, and the lyotropic liquid crystals CpCl/n-hexanol/brine and cromolyn/water. The influence that different media and degrees of alignment have on the dynamic properties of several molecules was explored. Different sized sugars were used and their self-diffusion was determined as well as conformation features using RDCs. The results obtained indicate that no influence is felt by the small molecules diffusion and conformational features studied within the alignment degree range studied, which was the 3, 5 and 6 % CpCl/n-hexanol/brine for diffusion, and 5 and 7.5 % CpCl/n-hexanol/brine for conformation. It was also possible to determine that the small molecules diffusion verified in the alignment media presented close values to the ones observed in water, reinforcing the idea of no conditioning of molecular properties in such media.

Cellulose micro/nano fibers conformational effects probed by nematic liquid crystal droplets

Probing micro-/nano-sized surface conformations, which are ubiquitous in biological systems, by using liquid crystal droplets, which change their ordering and optical appearance in response to the presence of more than ten times smaller cellulose based micro/nano fibers, might find new uses in a range of biological environments and sensors. Previous studies indicate that electrospun micro/nano cellulosic fibers produced from liquid crystalline solutions could present a twisted form [1]. In this work, we study the structures of nematic liquid crystal droplets threaded by cellulose fibers prepared from liquid crystalline and isotropic solutions as well as droplets pierced by spider-made fibers [2]. Planar anchoring at the fibers and planar and homeotropic at the drop surfaces allowed probing cellulose fibers different helical structures as well as aligned filaments.

Impact of using different radiation therapy techniques in breat cancer: contralateral breast dose

RESUMO: O cancro de mama e o mais frequente diagnoticado a indiv duos do sexo feminino. O conhecimento cientifico e a tecnologia tem permitido a cria ção de muitas e diferentes estrat egias para tratar esta patologia. A Radioterapia (RT) est a entre as diretrizes atuais para a maioria dos tratamentos de cancro de mama. No entanto, a radia ção e como uma arma de dois canos: apesar de tratar, pode ser indutora de neoplasias secund arias. A mama contralateral (CLB) e um orgão susceptivel de absorver doses com o tratamento da outra mama, potenciando o risco de desenvolver um tumor secund ario. Nos departamentos de radioterapia tem sido implementadas novas tecnicas relacionadas com a radia ção, com complexas estrat egias de administra ção da dose e resultados promissores. No entanto, algumas questões precisam de ser devidamente colocadas, tais como: E seguro avançar para tecnicas complexas para obter melhores indices de conformidade nos volumes alvo, em radioterapia de mama? O que acontece aos volumes alvo e aos tecidos saudaveis adjacentes? Quão exata e a administração de dose? Quais são as limitações e vantagens das técnicas e algoritmos atualmente usados? A resposta a estas questões e conseguida recorrendo a m etodos de Monte Carlo para modelar com precisão os diferentes componentes do equipamento produtor de radia ção(alvos, ltros, colimadores, etc), a m de obter uma descri cão apropriada dos campos de radia cão usados, bem como uma representa ção geometrica detalhada e a composição dos materiais que constituem os orgãos e os tecidos envolvidos. Este trabalho visa investigar o impacto de tratar cancro de mama esquerda usando diferentes tecnicas de radioterapia f-IMRT (intensidade modulada por planeamento direto), IMRT por planeamento inverso (IMRT2, usando 2 feixes; IMRT5, com 5 feixes) e DCART (arco conformacional dinamico) e os seus impactos em irradia ção da mama e na irradia ção indesejada dos tecidos saud aveis adjacentes. Dois algoritmos do sistema de planeamento iPlan da BrainLAB foram usados: Pencil Beam Convolution (PBC) e Monte Carlo comercial iMC. Foi ainda usado um modelo de Monte Carlo criado para o acelerador usado (Trilogy da VARIAN Medical Systems), no c odigo EGSnrc MC, para determinar as doses depositadas na mama contralateral. Para atingir este objetivo foi necess ario modelar o novo colimador multi-laminas High- De nition que nunca antes havia sido simulado. O modelo desenvolvido est a agora disponí vel no pacote do c odigo EGSnrc MC do National Research Council Canada (NRC). O acelerador simulado foi validado com medidas realizadas em agua e posteriormente com c alculos realizados no sistema de planeamento (TPS).As distribui ções de dose no volume alvo (PTV) e a dose nos orgãos de risco (OAR) foram comparadas atrav es da an alise de histogramas de dose-volume; an alise estati stica complementar foi realizadas usando o software IBM SPSS v20. Para o algoritmo PBC, todas as tecnicas proporcionaram uma cobertura adequada do PTV. No entanto, foram encontradas diferen cas estatisticamente significativas entre as t ecnicas, no PTV, nos OAR e ainda no padrão da distribui ção de dose pelos tecidos sãos. IMRT5 e DCART contribuem para maior dispersão de doses baixas pelos tecidos normais, mama direita, pulmão direito, cora cão e at e pelo pulmão esquerdo, quando comparados com as tecnicas tangenciais (f-IMRT e IMRT2). No entanto, os planos de IMRT5 melhoram a distribuição de dose no PTV apresentando melhor conformidade e homogeneidade no volume alvo e percentagens de dose mais baixas nos orgãos do mesmo lado. A t ecnica de DCART não apresenta vantagens comparativamente com as restantes t ecnicas investigadas. Foram tamb em identi cadas diferen cas entre os algoritmos de c alculos: em geral, o PBC estimou doses mais elevadas para o PTV, pulmão esquerdo e cora ção, do que os algoritmos de MC. Os algoritmos de MC, entre si, apresentaram resultados semelhantes (com dferen cas at e 2%). Considera-se que o PBC não e preciso na determina ção de dose em meios homog eneos e na região de build-up. Nesse sentido, atualmente na cl nica, a equipa da F sica realiza medi ções para adquirir dados para outro algoritmo de c alculo. Apesar de melhor homogeneidade e conformidade no PTV considera-se que h a um aumento de risco de cancro na mama contralateral quando se utilizam t ecnicas não-tangenciais. Os resultados globais dos estudos apresentados confirmam o excelente poder de previsão com precisão na determinação e c alculo das distribui ções de dose nos orgãos e tecidos das tecnicas de simulação de Monte Carlo usados.---------ABSTRACT:Breast cancer is the most frequent in women. Scienti c knowledge and technology have created many and di erent strategies to treat this pathology. Radiotherapy (RT) is in the actual standard guidelines for most of breast cancer treatments. However, radiation is a two-sword weapon: although it may heal cancer, it may also induce secondary cancer. The contralateral breast (CLB) is a susceptible organ to absorb doses with the treatment of the other breast, being at signi cant risk to develop a secondary tumor. New radiation related techniques, with more complex delivery strategies and promising results are being implemented and used in radiotherapy departments. However some questions have to be properly addressed, such as: Is it safe to move to complex techniques to achieve better conformation in the target volumes, in breast radiotherapy? What happens to the target volumes and surrounding healthy tissues? How accurate is dose delivery? What are the shortcomings and limitations of currently used treatment planning systems (TPS)? The answers to these questions largely rely in the use of Monte Carlo (MC) simulations using state-of-the-art computer programs to accurately model the di erent components of the equipment (target, lters, collimators, etc.) and obtain an adequate description of the radiation elds used, as well as the detailed geometric representation and material composition of organs and tissues. This work aims at investigating the impact of treating left breast cancer using di erent radiation therapy (RT) techniques f-IMRT (forwardly-planned intensity-modulated), inversely-planned IMRT (IMRT2, using 2 beams; IMRT5, using 5 beams) and dynamic conformal arc (DCART) RT and their e ects on the whole-breast irradiation and in the undesirable irradiation of the surrounding healthy tissues. Two algorithms of iPlan BrainLAB TPS were used: Pencil Beam Convolution (PBC)and commercial Monte Carlo (iMC). Furthermore, an accurate Monte Carlo (MC) model of the linear accelerator used (a Trilogy R VARIANR) was done with the EGSnrc MC code, to accurately determine the doses that reach the CLB. For this purpose it was necessary to model the new High De nition multileaf collimator that had never before been simulated. The model developed was then included on the EGSnrc MC package of National Research Council Canada (NRC). The linac was benchmarked with water measurements and later on validated against the TPS calculations. The dose distributions in the planning target volume (PTV) and the dose to the organs at risk (OAR) were compared analyzing dose-volume histograms; further statistical analysis was performed using IBM SPSS v20 software. For PBC, all the techniques provided adequate coverage of the PTV. However, statistically significant dose di erences were observed between the techniques, in the PTV, OAR and also in the pattern of dose distribution spreading into normal tissues. IMRT5 and DCART spread low doses into greater volumes of normal tissue, right breast, right lung, heart and even the left lung than tangential techniques (f-IMRT and IMRT2). However,IMRT5 plans improved distributions for the PTV, exhibiting better conformity and homogeneity in target and reduced high dose percentages in ipsilateral OAR. DCART did not present advantages over any of the techniques investigated. Di erences were also found comparing the calculation algorithms: PBC estimated higher doses for the PTV, ipsilateral lung and heart than the MC algorithms predicted. The MC algorithms presented similar results (within 2% di erences). The PBC algorithm was considered not accurate in determining the dose in heterogeneous media and in build-up regions. Therefore, a major e ort is being done at the clinic to acquire data to move from PBC to another calculation algorithm. Despite better PTV homogeneity and conformity there is an increased risk of CLB cancer development, when using non-tangential techniques. The overall results of the studies performed con rm the outstanding predictive power and accuracy in the assessment and calculation of dose distributions in organs and tissues rendered possible by the utilization and implementation of MC simulation techniques in RT TPS.

Towards modification of Medicago truncatula epigenome: genome editing with engineered nucleases

Periodic drought is the primary limitation of plant growth and crop yield. The rise of water demand caused by the increase in world population and climate change, leads to one of the biggest challenges of modern agriculture: to increase food and feed production. De novo DNA methylation is a process regulated by small interfering RNA (siRNAs), which play a role in plant response and adaptation to abiotic stress. In the particular case of water deficit, growing evidences suggest a link between the siRNA pathways and drought response in the model legume Medicago truncatula. As a first step to understand the role of DNA methylation under water stress, we have set up several bioinformatics and molecular methodologies allowing the design of Clustered regularly interspaced short palindromic repeats (CRISPR)/Cas9 systems and the assembly of TALENs (transcription activator-like effector nucleases), to target both dicer-like 3 (MtDCL3) and RNA-Dependent RNA polymerase (MtRDR2), enzymes of the RNA-directed DNA methylation pathway. TALENs efficiency was evaluated prior to plant transformation by a yeast-based assay using two different strategies to test TALENs activity: Polyacrylamide gel electrophoresis (PAGE) and Single strand conformation polymorphisms (SSCP). In this assay, yeast cells triple transformation emerged as good and rapid alternative to laborious yeast mating strategies. PAGE analysis might be a valuable tool to test TALENs efficacy in vivo if we could increase TALENs activity. SSCP-based approach proved to be ineffective due to the generation of several false positives. TALENs and CRISPR/Cas9 system constructed and designed in this work will in the future certainly enable the successful disruption of DCL3 and RDR2 genes and shed the light on the relationship between plant stress resistance and epigenetic regulation mediated by siRNAs in M.truncatula.

P53 and Rb tumor suppressor gene alterations in gastric cancer

Inactivation of tumor suppressor genes has been frequently observed in gastric carcinogenesis. Our purpose was to study the involvement of p53, APC, DCC, and Rb genes in gastric carcinoma. METHOD: Loss of heterozygosity of the p53, APC, DCC and Rb genes was studied in 22 gastric cancer tissues using polymerase chain reaction; single-strand conformation polymorphism of the p53 gene exons 5-6 and exons 7-8 was studied using 35S-dATP, and p53 expression was detected using a histological immunoperoxidase method with an anti-p53 clone. RESULTS AND DISCUSSION: No loss of heterozygosity was observed in any of these tumor suppressor genes; homozygous deletion was detected in the Rb gene in 23% (3/13) of the cases of intestinal-type gastric carcinoma. Eighteen (81.8%) cases showed band mobility shifts in exons 5-6 and/or 7-8 of the p53 gene. The presence of the p53 protein was positive in gastric cancer cells in 14 cases (63.6%). Normal gastric mucosa showed negative staining for p53; thus, the immunoreactivity was likely to represent mutant forms. The correlation of band mobility shift and the immunoreactivity to anti-p53 was not significant (P = .90). There was no correlation of gene alterations with the disease severity. CONCLUSIONS: The inactivation of Rb and p53 genes is involved in gastric carcinogenesis in our environment. Loss of the Rb gene observed only in the intestinal-type gastric cancer should be further evaluated in association with Helicobacter pylori infection. The p53 gene was affected in both intestinal and diffuse histological types of gastric cancer.