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Search Results: 1 - 10 of 376907 matches for " Julián Pérez-Flores "
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Alkaloids, Limonoids and Phenols from Meliaceae Species Decrease Survival and Performance of Hypsipyla Grandella Larvae  [PDF]
Julián Pérez-Flores, Sanford D. Eigenbrode, Luko Hilje-Quiroz
American Journal of Plant Sciences (AJPS) , 2012, DOI: 10.4236/ajps.2012.37117
Abstract: Meliaceae plants are distinguished by the attack of the shootborer Hypsipyla grandella and also for the occurrence of limonoids, alkaloids and phenolic compounds. Such compounds extracted from leaves of Meliaceae species Cedrela odorata L., Swietenia macrophylla King, Khaya senegalensis, Toona ciliata, and C. odorata grafted onto T. ciliata plants, were tested on C. odorata leaf disks to determine their effects on survival and performance of H. grandella larvae. Larval survival was assessed 2, 10 and 25 days after starting the bioassays. Leaf consumption and weight gain per larva, days to pupa and to adult stages, pupal weight and length, and moth wing appearance were assessed for larval performance. The three compunds from the four Meliaceae species and the grafted combination affected (P ≤ 0.02) larval leaf consumption, weight gain, time to pupa and to adult stages, wing development and larval survival of H. grandella. Pupa weight (P = 0.78, F = 0.72, d.f. = 18, 160) and length (P = 0.48, F = 0.98, d.f. = 18, 160) were similar regardless of the coumpound used. Limonoid reduced larval survival on the three dates of evaluation. Alkaloids decreased leaf consumption, weight gain of larvae and time needed to reach pupa and adult stages. Alkaloids from T. ciliata and phenols from C. odorata were the best coumpounds to reduce leaf consumption and weight gain. Alkaloids from the grafted plants caused 20% of H. grandella adults to form abnormal wings.
Human CD3γ, but not CD3δ, haploinsufficiency differentially impairs γδ versus αβ surface TCR expression
Mu?oz-Ruiz Miguel,Pérez-Flores Verónica,Garcillán Beatriz,Guardo Alberto C
BMC Immunology , 2013, DOI: 10.1186/1471-2172-14-3
Abstract: Background The T cell antigen receptors (TCR) of αβ and γδ T lymphocytes are believed to assemble in a similar fashion in humans. Firstly, αβ or γδ TCR chains incorporate a CD3δε dimer, then a CD3γε dimer and finally a ζζ homodimer, resulting in TCR complexes with the same CD3 dimer stoichiometry. Partial reduction in the expression of the highly homologous CD3γ and CD3δ proteins would thus be expected to have a similar impact in the assembly and surface expression of both TCR isotypes. To test this hypothesis, we compared the surface TCR expression of primary αβ and γδ T cells from healthy donors carrying a single null or leaky mutation in CD3G (γ+/ ) or CD3D (δ+/ , δ+/leaky) with that of normal controls. Results Although the partial reduction in the intracellular availability of CD3γ or CD3δ proteins was comparable as a consequence of the mutations, surface TCR expression measured with anti-CD3ε antibodies was significantly more decreased in γδ than in αβ T lymphocytes in CD3γ+/ individuals, whereas CD3δ+/ and CD3δ+/leaky donors showed a similar decrease of surface TCR in both T cell lineages. Therefore, surface γδ TCR expression was more dependent on available CD3γ than surface αβ TCR expression. Conclusions The results support the existence of differential structural constraints in the two human TCR isotypes regarding the incorporation of CD3γε and CD3δε dimers, as revealed by their discordant surface expression behaviour when confronted with reduced amounts of CD3γ, but not of the homologous CD3δ chain. A modified version of the prevailing TCR assembly model is proposed to accommodate these new data.
Lo público, lo privado y el espacio universitario: Reflexión bioética Behaviors in public, private and university environments
Manuel Pérez-Flores
Revista médica de Chile , 2012,
Abstract: Background: In contemporary democracies, rules of conduct, in public places, are established by law and in private places, by morality. Between both, there is a middle area or interface given by community consensus. In the Community area, rules are consensual among its members. Institutions are an example of such situation. The University, as an institution, without contradicting the law, regulates and requires a behavior that is consistent with its purpose, beyond the private sphere, especially in the Schools of Medicine. We analyze what happens and the underlying purposes that represent the concept of University and Medicine. Special importance is given to ethical, social and cultural analyses.
Quiste conjuntival de inclusión tras cirugía de estrabismo según técnica de retroinserción en asa
Pérez-Flores,M.I.; Ortiz-Rey,J.A.; Antón-Badiola,I.; Lorenzo-Carrero,J.;
Archivos de la Sociedad Espa?ola de Oftalmología , 2006, DOI: 10.4321/S0365-66912006001100007
Abstract: case report: a 24-year-old woman, with a history of infantile esotropia and dvd operated on in infancy, had strabismus surgery performed by us. four months later she presented with a cystic lesion that recurred after drainage and medical treatment. complete excision of the cystic lesion was therefore performed. discussion: the epithelial cells implanted on the sclera at the time of the most recent surgery may have been the origin of inclusion cyst which developed after the strabismus surgery. this suggests a possible relationship with the scleral suture as the mechanism of cyst formation, independent of the muscle position. complete excision is the recommended treatment for large cysts.
Book Review of "Coastal Chalk Cliff Instability"?
R. G. Antonio-Carpio, M. A. Pérez-Flores, D. Camargo-Guzmán,A. Alanís-Alcantar
Natural Hazards and Earth System Sciences (NHESS) & Discussions (NHESSD) , 2004,
Abstract: In the XIX century when Mexico City was much smaller than at present, there was non-regulated mining of building materials in a region of tuffs northwest of the city in an inhabited countryside. With the growth of the city during the XX century, this region was increasingly populated and in the 1970's many two-level bricks houses were built, without regard for underground caves created by the earlier extractions. Some ground sinkings in adjacent areas alarmed the residents who now are worried about this permanent hazard. An association of residents contracted a private company for a geophysical study in order to know the distribution of the caves. Resistivity measurements were taken in the area to detect the caves in order to alert city authorities. Resistivity data along most of the streets were collected with the array pole-dipole that consisted of three grounded electrodes. We performed 2-D dimensional inversions to the data in order to get a 2-D resistivity image of every street. This is similar to a resistivity cross-section of the ground but obtained from the inversion of pole-dipole and Schlumberger resistivity data simultaneously. Using the information of previous drills we modified our programming code in order to perform constrained inversion and to get more accurate resistivity models in agreement with the drills. From the resistivity models obtained for every street it was possible to produce a map which shows the horizontal distribution of the resistive bodies at a depth of 12m. These resistive bodies show coherent alignments that seem to correspond with a distributions of interconnected caves or tunnels used for extracting the sandy-tuffs. From these kind of interpretation method it was intended to get a more accurate horizontal distribution of the excavated areas in order to better know the urbanized area affected and lead the authorities to remedy the area with refill material. Full Article (PDF, 637 KB) Citation: Antonio-Carpio, R. G., Pérez-Flores, M. A., Camargo-Guzmán, D., and Alanís-Alcantar, A.: Use of resistivity measurements to detect urban caves in Mexico City and to assess the related hazard, Nat. Hazards Earth Syst. Sci., 4, 541-547, doi:10.5194/nhess-4-541-2004, 2004. Bibtex EndNote Reference Manager XML
Quiste conjuntival de inclusión tras cirugía de estrabismo según técnica de retroinserción en asa Conjunctival inclusion cyst after strabismus surgery by hang-back recession
M.I. Pérez-Flores,J.A. Ortiz-Rey,I. Antón-Badiola,J. Lorenzo-Carrero
Archivos de la Sociedad Espa?ola de Oftalmología , 2006,
Abstract: Caso clínico: Mujer de 24 a os con antecedentes de endotropía congénita más DVD operada en la infancia. Se realiza intervención quirúrgica y cuatro meses tras la cirugía presenta una lesión quística que recidiva tras drenaje y tratamiento médico. Se realiza exéresis completa de la lesión. Discusión: El origen de los quistes de inclusión conjuntivales tras cirugía de estrabismo sería la implantación escleral de células epiteliales. Sugerimos la relación con la sutura escleral como mecanismo de formación, independientemente de la posición del músculo. El tratamiento de elección en los quistes de gran tama o es la resección completa. Case report: A 24-year-old woman, with a history of infantile esotropia and DVD operated on in infancy, had strabismus surgery performed by us. Four months later she presented with a cystic lesion that recurred after drainage and medical treatment. Complete excision of the cystic lesion was therefore performed. Discussion: The epithelial cells implanted on the sclera at the time of the most recent surgery may have been the origin of inclusion cyst which developed after the strabismus surgery. This suggests a possible relationship with the scleral suture as the mechanism of cyst formation, independent of the muscle position. Complete excision is the recommended treatment for large cysts.
De Novo Polymerase Activity and Oligomerization of Hepatitis C Virus RNA-Dependent RNA-Polymerases from Genotypes 1 to 5
Pilar Clemente-Casares,Alberto J. López-Jiménez,Itxaso Bellón-Echeverría,José Antonio Encinar,Elisa Martínez-Alfaro,Ricardo Pérez-Flores,Antonio Mas
PLOS ONE , 2012, DOI: 10.1371/journal.pone.0018515
Abstract: Hepatitis C virus (HCV) shows a great geographical diversity reflected in the high number of circulating genotypes and subtypes. The response to HCV treatment is genotype specific, with the predominant genotype 1 showing the lowest rate of sustained virological response. Virally encoded enzymes are candidate targets for intervention. In particular, promising antiviral molecules are being developed to target the viral NS3/4A protease and NS5B polymerase. Most of the studies with the NS5B polymerase have been done with genotypes 1b and 2a, whilst information about other genotypes is scarce. Here, we have characterized the de novo activity of NS5B from genotypes 1 to 5, with emphasis on conditions for optimum activity and kinetic constants. Polymerase cooperativity was determined by calculating the Hill coefficient and oligomerization through a new FRET-based method. The Vmax/Km ratios were statistically different between genotype 1 and the other genotypes (p<0.001), mainly due to differences in Vmax values, but differences in the Hill coefficient and NS5B oligomerization were noted. Analysis of sequence changes among the studied polymerases and crystal structures show the αF helix as a structural component probably involved in NS5B-NS5B interactions. The viability of the interaction of αF and αT helixes was confirmed by docking studies and calculation of electrostatic surface potentials for genotype 1 and point mutants corresponding to mutations from different genotypes. Results presented in this study reveal the existence of genotypic differences in NS5B de novo activity and oligomerization. Furthermore, these results allow us to define two regions, one consisting of residues Glu128, Asp129, and Glu248, and the other consisting of residues of αT helix possibly involved in NS5B-NS5B interactions.
Apparent cross-talk of two signaling pathways that regulate Zea mays coleoptile growth
Buentello Volante,B; Díaz de León-Sánchez,F; Rivera-Cabrera,F; Aguilar Caballero,R; Ponce-Valadez,M; Sánchez de Jiménez,E; Pérez-Flores,LJ;
Phyton (Buenos Aires) , 2010,
Abstract: auxin and insulin promote zea mays embryo growth, induce s6 ribosomal protein (s6rp) phosphorylation, and promote specific protein synthesis. the objective of this research was to test a possible cross-talk between insulin and auxin transduction pathways in z. mays coleoptiles, typical auxin target tissues. auxin and insulin produced differential quantitative and qualitative stimulation of cytoplasmic and ribosomal protein phosphorylation, and specific patterns of de novo synthesized cytoplasmic proteins. in addition, insulin induced s6rp phosphorylation was strongly inhibited by rapamycin, indicating target of rapamycin (tor) kinase participation; auxin-induced s6rp phosphorylation was insensitive to this inhibitor. phosphatidic acid (pa), a second messenger of tor in metazoan, was also tested. it produced similar results to insulin and rapamycin sensitiveness, supporting the existence of tor pathway in plants and the participation of pa as an intermediate of insulin action. these results seem to imply that auxin and insulin induce z. mays coleoptile growth through two independent signal transduction pathways.
Carnitine Palmitoyltransferase 1B 531K Allele Carriers Sustain a Higher Respiratory Quotient after Aerobic Exercise, but β3-Adrenoceptor 64R Allele Does Not Affect Lipolysis: A Human Model
Eduardo Gómez-Gómez, Martín Efrén Ríos-Martínez, Elena Margarita Castro-Rodríguez, Mario Del-Toro-Equíhua, Mario Ramírez-Flores, Ivan Delgado-Enciso, Ana Lilia Pérez-Huitimea, Luz Margarita Baltazar-Rodríguez, Gilberto Velasco-Pineda, Jesús Mu?iz-Murguía
PLOS ONE , 2014, DOI: 10.1371/journal.pone.0096791
Abstract: Carnitine palmitoyltransferase IB (CPT1B) and adrenoceptor beta-3 (ADRB3) are critical regulators of fat metabolism. CPT1B transports free acyl groups into mitochondria for oxidation, and ADRB3 triggers lipolysis in adipocytes, and their respective polymorphisms E531K and W64R have been identified as indicators of obesity in population studies. It is therefore important to understand the effects of these mutations on ADRB3 and CPT1B function in adipose and skeletal muscle tissue, respectively. This study aimed to analyze the rate of lipolysis of plasma indicators (glycerol, free fatty acids, and beta hydroxybutyrate) and fat oxidation (through the non-protein respiratory quotient). These parameters were measured in 37 participants during 30 min of aerobic exercise at approximately 62% of maximal oxygen uptake, followed by 30 min of recovery. During recovery, mean respiratory quotient values were higher in K allele carriers than in non-carriers, indicating low post-exercise fatty acid oxidation rates. No significant differences in lipolysis or lipid oxidation were observed between R and W allele carriers of ADRB3 at any time during the aerobic load. The substitution of glutamic acid at position 531 by lysine in the CPT1B protein decreases the mitochondrial beta-oxidation pathway, which increases the non-protein respiratory quotient value during recovery from exercise. This may contribute to weight gain or reduced weight-loss following exercise.
Geological interpretation of Eastern Cuba Laterites from an airborne magnetic and radioactive isotope survey
Batista, J. A.;Blanco, J.;Pérez-Flores, M. A.;
Geofísica internacional , 2008,
Abstract: in eastern cuba area several geophysical techniques have been applied to distinguish the main geological characteristics of the laterites which are of economical importance for the extraction of iron, nickel and chrome. the geophysical measurements include an aeromagnetic survey and thorium (eth), potassium (k) and uranium (eu) isotope measurements. the results of gamma spectrometer measurements make a distinction between laterite reservoirs. the application of the magnetic and isotope methods allowed the determination of the distribution and development of the laterite crust, as well as the determination of hydrothermal alterations affecting the laterites, which is very useful for mining exploration and exploitation. such alterations indicate the presence of silicates, which have negative effects on the metallurgic process. it is known that laterite crust has a high content of eu and eth. from the content of the isotope abundance (eu and eth) it was possible to infer that moa laterites were formed before the mayari region. from the measurements it was also possible to infer the origin, thickness and age of the lateritic crust.
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