26 results on '"Carlos A. Amezcua"'
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2. AUTOLOGOUS TRANSFUSION IN LARGE VOLUME LIPOSUCTION. COHORT FOLLOW-UP
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Juan Daniel Naranjo-Hernández, Carlos Iván Amezcua-Equihua, Luis Antonio Vazquez-Robles, Raúl Esaú Flores- Barragán, Alexis Román- Matus, and Quitzia L Torres- Salazar
- Abstract
INTRODUCTION: With the increased knowledge about the physiology of liposuction, procedures that involve larger body surface area are now being performed, which means an increased risk of hemorrhage and the need for transfusion. Homologous blood transfusion poses well-known risks, prompting the use of alternative and safer techniques such as autologous donation. To demonstrate the utility of autologousOBJECTIVE: transfusion in a cohort of patients undergoing large volume liposuction. Observational, retrospective andMETHODS: longitudinal cohort study in patients undergoing liposuction, in the period 2017-2021. Autologous donation was performed one month and two weeks prior to surgery, ensuring that all patients were prescribed medication and prophylactic dietary measures to avoid hemoglobin depletion. 40 les of women between 26 and 46 years of age, with a bodyRESULTS AND CONCLUSIONS: mass index between 24 and 30 m/kg2 and a median aspirated volume of 6.3 Lt were analyzed. Quantied bleeding averaged 675 cc. Both initial hemoglobin and hematocrit had statistically signicant differences with values in the postoperative period (pn all. However, vital signs remained stable and no transfusion-associated adverse events occurred. Autologous transfusion is an excellent strategy for the management of bleeding in large volume liposuction.
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- 2022
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3. Removal of modeling substance in left buttock of a patient with ASIA syndrome
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Luis Antonio Vazquez Robles, M.D., Carlos Ivan Amezcua Equihua, M.D., Juan Daniel Naranjo Hernandez, M.D., Omar Alexander Hernandez Hernandez, M.D., Javier Noel Chavarria Duarte, M.D., Jose Jesus Fabian Mendez, M.D., Mabel Preciosa San Juan Medrano, M.D., and Alfredo Vega Angulo, M.D.
- Abstract
Objective: To describe the case of a patient with modeling disease and overview the literature. Case description: 62-year-old female patient with a history of injection with modeling substances 20 years ago presenting late onset reaction to these and ASIA syndrome, managed with surgical debridement, negative pressure system and skin graft placement. Conclusion: Complications due to the use of biopolymers can be severe and their management must be multidisciplinary. Keywords: modeling disease, biopolymers, skin grafting.
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- 2022
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4. Biodisponibilidad de lisina en dos pastas de soya con diferente nivel de actividad ureásica en pollos de engorda
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Arturo Cortes Cuevas, Carlos Martínez Amezcua, Gabriela Gómez Verduzco, Carlos López Coello, and Ernesto Avila González
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Animal culture ,SF1-1100 ,Veterinary medicine ,SF600-1100 - Abstract
Para conocer la biodisponi bilidad de lisina para pollos de dos pastas de soya (PSA y PSB), con diferente actividad ureásica (AU 0.11 y 0.17 unidades de incremento de pH), se realizó el presente experimento. Se utili zaron 210 pollitos Ross de 1 a 21 días de edad, los cuales se distribuyeron al azar en 7 tratamientos con tres repetici ones. Los tratamientos fueron: 1) dieta basal sorgo-soya-ajonjolí (deficiente en lisina), 2) dieta basal + 0.0 5% de L-lisina, 3) dieta basal+0.10% de L-lisina, 4) dieta basal+0.05% de lisina a partir de PSA, 5) dieta basal+0.10% de lisina a partir de PSA, 6) dieta basal+0.05% de lisina a partir de PSB y 7) dieta basal+0.10% de lisina a partir de PSB. Los resultados de crecimiento, se explicaron mediante la ecuación de regresión lineal múltiple, con los datos de ganancia de peso, consumos de lisina sintética o consumos de lisina a partir de las pastas de soya fue Y= 375 .419 + 0.0378 X1 + 0.0366 X2 + 0.0376 X3; en donde X1 correspondió a la complementación con L-lisina, X2 con la PS A (con adición de cascarilla cruda) y X3 con la PSB (con adición de cascarilla cocida). Al comparar la pendiente de la pasta de soya A o B, con la obtenida con L-lisina (100%), se tuvieron biodisponibilidades de lisina de 97 y 99 % p ara las pastas de soya A y B respectivamente. Estos resultados indican que la AU de la pasta de soya afecta la biod isponibilidad de lis ina; a mayor actividad ureásica, menor es la disponibilidad.
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- 2014
5. Collaborative Study to Validate Purity Determination by 1H Quantitative NMR Spectroscopy by Using Internal Calibration Methodology
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Sitaram Bhavaraju, Yang Liu, Taro Higano, Kana Yamamoto, Yuzo Nishizaki, Stefano Todisco, Ryuichi Sawa, Vito Gallo, Thomas Hausler, Neeraj Singh, Yukihiro Goda, Tsuyoshi Kato, Yoshiaki Iwamoto, Ryuichi Watanabe, Naoki Sugimoto, Joseph Ray, Toru Miura, Anton Bzhelyansky, Christian Geletneky, Bernd Diehl, Katsuya Ofuji, Carlos A. Amezcua, Taichi Yamazaki, Elina Zailer, and Kazuhiro Fujita
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Chromatography ,Quantitative nmr ,010405 organic chemistry ,Chemistry ,Metrological traceability ,General Chemistry ,General Medicine ,010402 general chemistry ,01 natural sciences ,0104 chemical sciences ,Organic molecules ,Certified reference materials ,Drug Discovery ,Calibration ,Measurement uncertainty ,Spectroscopy ,Reference standards - Abstract
NMR spectroscopy has recently been utilized to determine the absolute amounts of organic molecules with metrological traceability since signal intensity is directly proportional to the number of each nucleus in a molecule. The NMR methodology that uses hydrogen nucleus (1H) to quantify chemicals is called quantitative 1H-NMR (1H qNMR). The quantitative method using 1H qNMR for determining the purity or content of chemicals has been adopted into some compendial guidelines and official standards. However, there are still few reports in the literature regarding validation of 1H qNMR methodology. Here, we coordinated an international collaborative study to validate a 1H qNMR based on the use of an internal calibration methodology. Thirteen laboratories participated in this study, and the purities of three samples were individually measured using 1H qNMR method. The three samples were all certified via conventional primary methods of measurement, such as butyl p-hydroxybenzoate Japanese Pharmacopeia (JP) reference standard certified by mass balance; benzoic acid certified reference material (CRM) certified by coulometric titration; fludioxonil CRM certified by a combination of freezing point depression method and 1H qNMR. For each sample, 1H qNMR experiments were optimized before quantitative analysis. The results showed that the measured values of each sample were equivalent to the corresponding reference labeled value. Furthermore, assessment of these 1H qNMR data using the normalized error, En-value, concluded that statistically 1H qNMR has the competence to obtain the same quantification performance and accuracy as the conventional primary methods of measurement.
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- 2020
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6. Biodisponibilidad de lisina para el pollo en crecimiento de cuatro harinas de subproductos avícolas
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Arturo Cortes Cuevas, Carlos Martínez Amezcua, and Ernesto Avila González
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Animal culture ,SF1-1100 ,Veterinary medicine ,SF600-1100 - Abstract
Para conocer la biodisponibilidad de lisina para el pollo de cuatro lotes de harinas de subproductos avícolas (HSA) mexicanas, se realizaron dos experimentos. En el Exp 1, se emplearon 168 pollitos de 1 a 21 días de edad y en el Exp 2, 210 pollitos de 7 a 21 días, en ambos experimentos las aves se distribuyeron completamente al azar en siete tratamientos con tres repeticiones cada uno. Los tratamientos fueron, 1) dieta basal sorgo-soya-ajonjolí (deficiente en lisina), 2) dieta basal + 0.05% de L-lisina, 3) dieta basal+0.10% de L-lisina, 4) dieta basal+0.05% de lisina a partir de HSA A o B, 5) dieta basal+0.10% de lisina a partir de HSA A o B, 6) dieta basal+0.05% de lisina a partir de HSA C o D y 7) dieta basal+0.10% de lisina a partir de HSA C o D. Los resultados del crecimiento se explicaron por la ecuación de regresión lineal múltiple de, Y=265.074+0.04288X1+0.0417X2+0.04085X3 , en donde X1 fue L-lisina, X2 la HSA A y X3 la HSA C (Exp 1) y del Exp 2 por Y=129.131+ 0.06764X1+0.06437X2+0.06614X3, en donde X1 fue L-lisina, X2 la HSA B y X3 la HSA D. Al comparar las pendientes de las HSA, con la de L-lisina considerada como 100 %, se obtuvieron biodisponibilidades de la HSA A de 97.2 %, C de 95.2 %, B de 95.2 % y D de 97.8 %. En base a los resultados obtenidos, se puede concluir que la calidad proteica de los cuatro lotes de harinas evaluadas, resultaron similares y de buena calidad.
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- 2011
7. Response of Zea mays var. Jala to Burkholderia sp. and Klebsiella oxytogena under reduced urea dose
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Juan Luis Ignacio-De la Cruz, Juan Carlos Carrillos-Amezcua, Juan Manuel Sánchez-Yáñez, and Dieter Plata-Guzmán
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chemistry.chemical_compound ,Klebsiella ,chemistry ,General Engineering ,Urea ,General Earth and Planetary Sciences ,Biology ,biology.organism_classification ,Zea mays ,General Environmental Science ,Burkholderia sp ,Microbiology - Abstract
Introduction: The growing of maize (zea mays L.) in Latin America is carried out under the intensive production system, which causes loss of soil fertility due to excessive nitrogen fertilizer. Objective: Analyzing the response of maize var. Jala to genera of plant growth promoting bacteria (PGPB) endophytes of maize var. Mexicana (teocintle) when using nitrogen fertilizer such as urea at 50 % under greenhouse and soil conditions. Methodology: A randomized block design was established with five treatments, three controls and twenty repetitions. The treatments with inoculated maize seeds and 50 % urea were: Burkholderia (KO) and Burkholderia sp. 14 (B14); the controls were: non-inoculated maize with 50 % urea (RC1), non-inoculated maize irrigated with water (FC) and non-inoculated maize with 100 % urea (RC2). The experiments were established under greenhouse and soil conditions. The response variables were radical dry weight (RDW) and fresh weight of grain (FWG). ANOVA and Tukey’s mean comparison (P ≤ 0.01) were carried out. Results: In both environments, treatment B14 showed statistically higher values than those obtained with FC (full control), but statistically equal to RC2 (relative control). Study limitations: Maize varieties have specific and beneficial endophytic PGPB genera, which are not necessarily for regional varieties. Originality: PGPB endophytes from teocintle (ancestor of maize) were used because of their close genetic relationship with the maize var. Jala. Conclusion: PGPB endophytes from teocintle are a viable option for sustainable maize production.
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- 2020
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8. Complex abnormality combinations between the scleritome and the sclerites of Chiton articulatus (Mollusca: Polyplacophora): New findings for the teratological classification
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Jorge Saúl Ramírez-Pérez, Bibiana Vargas-Trejo, Carlos Alberto Amezcua-Gomez, Nancy C. Saavedra-Sotelo, Brenda Paola Ramirez-Santana, Omar Hernando Avila-Poveda, Carlos Melendez-Galicia, and Pedro Martinez-Diaz
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0106 biological sciences ,Coalescence (physics) ,Sclerite ,010607 zoology ,Anatomy ,Biology ,biology.organism_classification ,010603 evolutionary biology ,01 natural sciences ,Polyplacophora ,Homogeneous ,Animal Science and Zoology ,Chiton ,Abnormality ,Mollusca - Abstract
Teratological diagnosis in polyplacophorans has mostly been based on primary structure (Chiton scleritome) with four types (hypermerism, hypomerism, coalescence and splitting), including some deformities in plates; however, diagnoses are hardly detailed for each sclerite. As part of a monthly research campaign conducted by a year investigating Chiton articulatus, we found several cases with a complex combination of abnormalities (chiton scleritome + sclerites) that complement the previous classification. Identification and diagnosis of abnormalities were assigned in terms of sclerite number, number of slits per side in the insertion area of intermediate sclerites and the merging grade between sclerites. Slit and slit-ray numbers were baseline to identify combination of abnormalities; the slit formula of Chiton articulatus is 13–18[I]/1[II-VII]/16–22[VIII]. We found four abnormality cases with combinations among them: a) perfect hypomerism, b) heterogeneous coalescence, c) homogeneous coalescence, d) imperfect hypermerism. Heterogeneous coalescence was most common abnormality, with a different merging degree between sclerites and with specimens showing combinations of abnormal states such as: normality/coalescence, coalescence/hypomerism, coalescence/hypermerism and normality/hypermerism; so these complex abnormalities can generates asymmetry between the right and left side of a chiton. We postulate that coalescence is an intermediate step toward perfect hypomerism or perfect hypermerism. The width/length ratio suggests that an abnormal chiton increases its width to compensate and retain a normal body appearance despite different degrees of abnormal development.
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- 2019
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9. Biodisponibilidad de lisina para el pollo en crecimiento de cuatro harinas de subproductos avícolas
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Arturo Cortés Cuevas, Carlos Martínez Amezcua, and Ernesto Avila González
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Harinas ,Subproductos avícolas ,Pollo ,Biodisponbilidad lisina ,Parámetros productivos ,Animal culture ,SF1-1100 ,Veterinary medicine ,SF600-1100 - Abstract
Para conocer la biodisponibilidad de lisina para el pollo de cuatro lotes de harinas de subproductos avícolas (HSA) mexicanas, se realizaron dos experimentos. En el Exp 1, se emplearon 168 pollitos de 1 a 21 días de edad y en el Exp 2, 210 pollitos de 7 a 21 días, en ambos experimentos las aves se distribuyeron completamente al azar en siete tratamientos con tres repeticiones cada uno.
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- 2012
10. Prevalence of neurological manifestations in COVID-19 and their association with mortality
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Carlos, C.R., primary, Gerardo, M.M., additional, Jaime, O.G., additional, Isauro, G.H.L., additional, Dios, A.P.J., additional, Wilmar, Cortez Saldias, additional, Jesús, Garza Montalvo Luis, additional, Thania, Deoca Mora, additional, Victor, Marín González, additional, Manuel, Morales Sánchez Juan, additional, Elizabeth, Riley Moguel Ámbar, additional, Alberto, Urcid Garcia Luis, additional, Arturo, Rojo Noriega Fernando, additional, Samuel, Zúñiga Córdova Jonathan, additional, Roy, Ferrufino Mejia Bill, additional, Alan, Juárez Jiménez Gustavo, additional, Antonio, Mejía Frías Alberto, additional, Guillermo, Luna Álvarez, additional, and Carlos, Landeta Amezcua, additional
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- 2021
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11. First records of Argonauta spp. collected in the wild and as prey of larger pelagic in the Mexican Central Pacific
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Carlos A Amezcua Gómez, Bernabé Aguilar Palomino, Mirella Saucedo Lozano, Jesús Emilio Michel Morfín, and Víctor Landa Jaime
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Fishery ,Geography ,biology ,Argonauta cornuta ,Biogeography ,Fishing ,Pelagic zone ,Environmental pollution ,Argonauta nouryi ,General Medicine ,biology.organism_classification ,Predation ,Cephalopod - Abstract
The first records of the pelagic cephalopod Argonauta nouryi nbsp Lorois captured alive in shallow waters of the Central Mexican Pacific are presented complementing such information with a brief analysis of specimens of Argonauta cornuta nbsp Linnaeus from stomach contents of commercial fish caught in the sport fishing of said region
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- 2018
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12. Flexible shift scheduling for a call centre using column generation
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Emilio Zamudio Gutierrez, Omar Rojas, Elias Olivares-Benitez, and Carlos Campos Amezcua
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Flexibility (engineering) ,Schedule ,Mathematical optimization ,Job shop scheduling ,Computer science ,Programming paradigm ,Scheduling (production processes) ,Column generation ,Time horizon ,Management Science and Operations Research ,Call centre - Abstract
A shift scheduling problem for a call centre is solved by applying a column generation method. The objective is to find an employee schedule within the planning horizon that meets staffing requirements provided by the customer and that minimises the costs of excess-staffing and under-staffing. To solve the problem, two iterative models were used: the first being a mixed integer-linear programming model, the master problem, and the second being a column generation model. In a first approach, the master problem was solved considering a fixed number of shift patterns. The second approach was to use both models iteratively to generate shift patterns to be used in the master problem. Both approaches met all constraints relatively fast, but the column generation model decreased the cost considerably when cheaper shift patterns were generated. The models contribute to the current literature by providing flexibility to consider under-coverage and over-coverage at two levels.
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- 2021
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13. Enabling adoption of 2D-NMR for the higher order structure assessment of monoclonal antibody therapeutics
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Peter Schmieder, Ryan M. Evans, Robert G. Brinson, Chad W. Lawrence, Kristian Schweimer, Yves Aubin, Ping Xu, Göran Widmalm, Andreas Blomgren, Hamish G. Grant, Anthony J. Kearsley, John P. Marino, Janez Plavec, John B. Jordan, Geneviève Gingras, Scott A. Bradley, Koichi Kato, Stuart Parnham, Patrick N. Reardon, John R. Cort, David W. Keizer, Edward R. Zartler, Feng Ni, Frank Delaglio, Gregor Ilc, Saeko Yanaka, David A. Keire, Jonas Ståhle, Mats Wikström, Luke W. Arbogast, Alfred Ross, Thea Suter-Stahel, Darón I. Freedberg, Ana Carolina de Mattos Zeri, Maurício L. Sforça, Nils Trieloff, Desiree Tsao, Torgny Rundlöf, Xinying Jia, Kang Chen, Ken Skidmore, Gregory K. Pierens, Houman Ghasriani, Donna M. Baldisseri, Carlos A. Amezcua, Mehdi Mobli, Julie Yu Wei, Christina M. Szabo, and Gerhard Wider
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Magnetic Resonance Spectroscopy ,Computer science ,Immunology ,Biopharmaceutics ,Chemometrics ,03 medical and health sciences ,0302 clinical medicine ,Report ,Immunology and Allergy ,Humans ,comparability ,nuclear magnetic resonance spectroscopy (NMR) ,030304 developmental biology ,0303 health sciences ,higher order structure ,business.industry ,Antibodies, Monoclonal ,Reproducibility of Results ,Measurement reliability ,NISTmAb ,chemometrics ,Biopharmaceutical manufacturing ,Biopharmaceutical ,030220 oncology & carcinogenesis ,New product development ,NIST ,Biochemical engineering ,monoclonal antibody (mAb) therapeutics ,business ,Laboratories ,Higher Order Structure ,Two-dimensional nuclear magnetic resonance spectroscopy - Abstract
The increased interest in using monoclonal antibodies (mAbs) as a platform for biopharmaceuticals has led to the need for new analytical techniques that can precisely assess physicochemical properties of these large and very complex drugs for the purpose of correctly identifying quality attributes (QA). One QA, higher order structure (HOS), is unique to biopharmaceuticals and essential for establishing consistency in biopharmaceutical manufacturing, detecting process-related variations from manufacturing changes and establishing comparability between biologic products. To address this measurement challenge, two-dimensional nuclear magnetic resonance spectroscopy (2D-NMR) methods were introduced that allow for the precise atomic-level comparison of the HOS between two proteins, including mAbs. Here, an inter-laboratory comparison involving 26 industrial, government and academic laboratories worldwide was performed as a benchmark using the NISTmAb, from the National Institute of Standards and Technology (NIST), to facilitate the translation of the 2D-NMR method into routine use for biopharmaceutical product development. Two-dimensional 1H,15N and 1H,13C NMR spectra were acquired with harmonized experimental protocols on the unlabeled Fab domain and a uniformly enriched-15N, 20%-13C-enriched system suitability sample derived from the NISTmAb. Chemometric analyses from over 400 spectral maps acquired on 39 different NMR spectrometers ranging from 500 MHz to 900 MHz demonstrate spectral fingerprints that are fit-for-purpose for the assessment of HOS. The 2D-NMR method is shown to provide the measurement reliability needed to move the technique from an emerging technology to a harmonized, routine measurement that can be generally applied with great confidence to high precision assessments of the HOS of mAb-based biotherapeutics.
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- 2019
14. Improvement of resolution for brain coupled metabolites by optimized 1H MRS at 7 T
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Elizabeth A. Maher, Aditya Patel, Lana G. Kaiser, Ivan E. Dimitrov, Carlos A. Amezcua, Deborah Douglas, and Changho Choi
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Adult ,Male ,Magnetic Resonance Spectroscopy ,Resolution (mass spectrometry) ,Phantoms, Imaging ,Chemistry ,Glutamine ,Brain ,Glutamic Acid ,Glutathione ,In vivo tests ,Young Adult ,chemistry.chemical_compound ,Nuclear magnetic resonance ,Yield (chemistry) ,Healthy volunteers ,Humans ,Molecular Medicine ,Female ,Radiology, Nuclear Medicine and imaging ,Spectral fitting ,Spectroscopy - Abstract
Resolution enhancement for glutamate (Glu), glutamine (Gln) and glutathione (GSH) in the human brain by TE-optimized point-resolved spectroscopy (PRESS) at 7 T is reported. Sub-TE dependences of the multiplets of Glu, Gln, GSH, γ-aminobutyric acid (GABA) and N-acetylaspartate (NAA) at 2.2–2.6 ppm were investigated with density matrix simulations, incorporating three-dimensional volume localization. The numerical simulations indicated that the C4-proton multiplets can be completely separated with (TE1, TE2) = (37, 63) ms, as a result of a narrowing of the multiplets and suppression of the NAA 2.5 ppm signal. Phantom experiments reproduced the signal yield and lineshape from simulations within experimental errors. In vivo tests of optimized PRESS were conducted on the prefrontal cortex of six healthy volunteers. In spectral fitting by LCModel, Cramer–Rao lower bounds (CRLBs) of Glu, Gln and GSH were 2 ± 1, 5 ± 1 and 6 ± 2 (mean ± SD), respectively. To evaluate the performance of the optimized PRESS method under identical experimental conditions, stimulated-echo spectra were acquired with (TE, TM) = (14, 37) and (74, 68) ms. The CRLB of Glu was similar between PRESS and short-TE stimulated-echo acquisition mode (STEAM), but the CRLBs of Gln and GSH were lower in PRESS than in both STEAM acquisitions. Copyright © 2010 John Wiley & Sons, Ltd.
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- 2010
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15. Signal transduction pathway of TonB-dependent transporters
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Andrew D. Ferguson, Rama Ranganathan, Yogarany Chelliah, Michael K. Rosen, Carlos A. Amezcua, Najeeb Halabi, and Johann Deisenhofer
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Models, Molecular ,Protein Conformation ,Allosteric regulation ,Biophysics ,Biological Transport, Active ,Receptors, Cell Surface ,Biology ,Biophysical Phenomena ,Protein structure ,Bacterial Proteins ,Escherichia coli ,Nuclear Magnetic Resonance, Biomolecular ,Multidisciplinary ,Pseudomonas putida ,Escherichia coli Proteins ,Membrane Proteins ,Transporter ,Biological Sciences ,Recombinant Proteins ,Protein Structure, Tertiary ,Cell biology ,Membrane protein ,Cytoplasm ,Mutagenesis, Site-Directed ,Statistical coupling analysis ,Signal transduction ,Bacterial outer membrane ,Signal Transduction - Abstract
Transcription of the ferric citrate import system is regulated by ferric citrate binding to the outer membrane transporter FecA. A signal indicating transporter occupancy is relayed across the outer membrane to energy-transducing and regulatory proteins embedded in the cytoplasmic membrane. Because transcriptional activation is not coupled to ferric citrate import, an allosteric mechanism underlies this complex signaling mechanism. Using evolution-based statistical analysis we have identified a sparse but structurally connected network of residues that links distant functional sites in FecA. Functional analyses of these positions confirm their involvement in the mechanism that regulates transcriptional activation in response to ferric citrate binding at the cell surface. This mechanism appears to be conserved and provides the structural basis for the allosteric signaling of TonB-dependent transporters.
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- 2007
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16. Total Synthesis of Nominal Diazonamides-Part 2: On the True Structure and Origin of Natural Isolates
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Anthony W. G. Burgett, Patrick G. Harran, Jing Li, Carlos A. Amezcua, and Lothar Esser
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chemistry.chemical_compound ,Natural product ,Chemistry ,Stereochemistry ,Structure (category theory) ,Total synthesis ,General Chemistry ,Crystal structure ,Diazonamide B ,Catalysis ,Derivative (chemistry) - Abstract
In the preceding communication we described a fully synthetic pathway to the structure proposed for ( )-diazonamide A (1, Scheme 1).[1] This material is not identical to the natural product, which raises the obvious question: What is the true structure of diazonamide A? Herein we provide an answer. In addition, we report that defined synthetic entity 8 induces, with equal potency, a toxic phenotype in cell culture indistinguishable from that produced by natural ( )-diazonamide A. Spectroscopic data for the heterocyclic cores of diazonamides A and B are nearly identical.[2] So when the crystal structure of a p-bromobenzamide derivative of diazonamide B was reported as 3,[2a] the diazonamide A assignment Scheme 1. Initial diazonamide structure assignments.
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- 2001
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17. Synthesis and comparative reactivity of thiomorpholine–borane: aqueous hydrolysis and oxidation by hypochlorite
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Carlos A. Amezcua, Henry C. Kelly, and Kevin E. Bell
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Aqueous solution ,Inorganic chemistry ,Hypochlorite ,chemistry.chemical_element ,Sulfoxide ,Borane ,Medicinal chemistry ,Sulfur ,Inorganic Chemistry ,chemistry.chemical_compound ,Hydrolysis ,Thiomorpholine ,chemistry ,Materials Chemistry ,Reactivity (chemistry) ,Physical and Theoretical Chemistry - Abstract
Thiomorpholine-N-borane was synthesized via amine displacement of BH3 from tetrahydrofuran–borane which had been prepared from NaBH4 and BF3·Et2O in tetrahydrofuran. Acid-catalyzed hydrolysis occurs only slightly faster than for morpholine–borane, the difference being attributed to a small difference in the electronic inductive effects of sulfur and oxygen in the 4-position of the respective adducts. Reaction with NaOCl exhibits a stoichiometric [OCl−]:[S(CH2)4NHBH3] ratio of 5:1. This is attributed to consumption of 3 mol of hypochlorite for the oxidation of hydridic hydrogen in BH3, one for the chlorination of nitrogen and another in attack at sulfur presumably resulting in sulfoxide formation. At pH 9.1–10.4, the initial reaction of hypochlorite with thiomorpholine–borane is several times faster than with morpholine–borane and, unlike the reaction with morpholine–borane, relatively insensitive to pH. Whereas hypochlorite oxidation of morpholine–borane has been proposed to occur primarily through reaction with HOCl, it is speculated that thiomorpholine–borane is also susceptible to attack by hypochlorite ion.
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- 1999
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18. NMR vs. molecular modeling. Part IV—conformational analysis of menthone and isomenthone imines
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Carlos A. Amezcua and William B. Smith
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chemistry.chemical_classification ,Allylic strain ,Molecular model ,Chemistry ,Stereochemistry ,General Chemistry ,Carbon-13 NMR ,Menthone ,chemistry.chemical_compound ,Proton NMR ,General Materials Science ,Conformational isomerism ,Isopropyl ,Alkyl - Abstract
The conformational analysis of a series of menthone and isomenthone imines was accomplished by 1HNMR spectroscopy and was compared with molecular modeling computations. The (E) menthone derivatives contain about 20% of a 2,5-diaxial chair conformer at room temperature (22–23°C), whereas in the (E)- and (Z)-isomenthone counterparts the major conformer has axial isopropyl and equatorial methyl groups. These peculiar conformations are a consequence of pseudo-allylic A(1,3) interactions between the isopropyl group and the non-bonded pair of electrons of the nitrogen, which dominate the axial–axial interactions between the alkyl chains and the protons of the ring in the isomenthone imines and are of considerable importance in the menthone derivatives. Copyright © 1999 John Wiley & Sons, Ltd.
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- 1999
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19. NMR versus molecular modelling: menthone and isomenthone
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Carlos A. Amezcua and William B. Smith
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Electronegativity ,chemistry.chemical_compound ,chemistry ,Computational chemistry ,Hydrogen bond ,Ab initio quantum chemistry methods ,Substituent ,Proton NMR ,General Materials Science ,General Chemistry ,Conformational isomerism ,Isopropyl ,Cis–trans isomerism - Abstract
trans-2-Isopropyl-5-methylcyclohexanone (menthone) may be considered as locked in the diequatorial conformer. However, the cis isomer (isomenthone) may exist in two major conformations with the isopropyl group either equatorial or axial. No measure of the equilibrium mix has been determined previously. Proton NMR allows such a determination at room temperature via the vicinal couplings between protons on carbons 5 and 6. Combined with modelling results, the calculated value with the isopropyl axial was 79%, of the total in good agreement with an earlier prediction. Two different conformer searching programs were employed to determine the various conformer populations. It was found that molecular mechanics estimates of the Boltzmann distributions varied considerably from the experimental results. These differences were not due to substituent electronegativity effects or to hydrogen bonding with the deuterochloroform solvent. Semiempirical PM3 and low-level ab initio calculations of the conformer energies also failed to account adequately for the conformer populations. DFT calculations (Becke3LYP/6–31G*) with zero-point energy corrections gave results most consistent with the experimentally determined values (67.5% axial isopropyl conformer). © 1988 John Wiley & Sons, Ltd.
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- 1998
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20. Assessment of higher order structure comparability in therapeutic proteins using nuclear magnetic resonance spectroscopy
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Carlos A. Amezcua and Christina M. Szabo
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Correlation coefficient ,Chemistry ,Protein Conformation ,Comparability ,Analytical chemistry ,Pharmaceutical Science ,Proteins ,Nuclear magnetic resonance spectroscopy ,Weight range ,NMR spectra database ,Aprotinin ,Pharmaceutical Preparations ,Albumins ,Linear regression ,Linear Models ,Animals ,Cattle ,Spectroscopy ,Higher Order Structure ,Nuclear Magnetic Resonance, Biomolecular - Abstract
In this work, we applied nuclear magnetic resonance (NMR) spectroscopy to rapidly assess higher order structure (HOS) comparability in protein samples. Using a variation of the NMR fingerprinting approach described by Panjwani et al. [2010. J Pharm Sci 99(8):3334–3342], three nonglycosylated proteins spanning a molecular weight range of 6.5–67 kDa were analyzed. A simple statistical method termed easy comparability of HOS by NMR (ECHOS-NMR) was developed. In this method, HOS similarity between two samples is measured via the correlation coefficient derived from linear regression analysis of binned NMR spectra. Applications of this method include HOS comparability assessment during new product development, manufacturing process changes, supplier changes, next-generation products, and the development of biosimilars to name just a few. We foresee ECHOS-NMR becoming a routine technique applied to comparability exercises used to complement data from other analytical techniques.
- Published
- 2012
21. ChemInform Abstract: Total Synthesis of Nominal Diazonamides. Part 2. On the True Structure and Origin of Natural Isolates
- Author
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Patrick G. Harran, Anthony W. G. Burgett, Lothar Esser, Carlos A. Amezcua, and Jing Li
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chemistry.chemical_compound ,Natural product ,chemistry ,Stereochemistry ,Structure (category theory) ,Total synthesis ,General Medicine ,Crystal structure ,Diazonamide B ,Derivative (chemistry) - Abstract
In the preceding communication we described a fully synthetic pathway to the structure proposed for ( )-diazonamide A (1, Scheme 1).[1] This material is not identical to the natural product, which raises the obvious question: What is the true structure of diazonamide A? Herein we provide an answer. In addition, we report that defined synthetic entity 8 induces, with equal potency, a toxic phenotype in cell culture indistinguishable from that produced by natural ( )-diazonamide A. Spectroscopic data for the heterocyclic cores of diazonamides A and B are nearly identical.[2] So when the crystal structure of a p-bromobenzamide derivative of diazonamide B was reported as 3,[2a] the diazonamide A assignment Scheme 1. Initial diazonamide structure assignments.
- Published
- 2010
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22. Molecular basis of coiled coil coactivator recruitment by the aryl hydrocarbon receptor nuclear translocator (ARNT)
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Paul B. Card, Carlos A. Amezcua, Kevin H. Gardner, and Carrie L. Partch
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Aryl hydrocarbon receptor nuclear translocator ,Magnetic Resonance Spectroscopy ,Amino Acid Motifs ,Molecular Sequence Data ,Biology ,Biochemistry ,Protein Structure, Secondary ,Transactivation ,Protein structure ,PAS domain ,Coactivator ,Protein Interaction Mapping ,Basic Helix-Loop-Helix Transcription Factors ,Animals ,Humans ,Amino Acid Sequence ,Nuclear protein ,Molecular Biology ,Conserved Sequence ,Coiled coil ,Binding Sites ,Aryl Hydrocarbon Receptor Nuclear Translocator ,Mechanisms of Signal Transduction ,Nuclear Proteins ,Cell Biology ,Cell biology ,Protein Structure, Tertiary ,Nuclear receptor ,Mutation ,Trans-Activators ,Peptides ,Protein Binding - Abstract
The aryl hydrocarbon receptor nuclear translocator (ARNT) serves as the obligate heterodimeric partner for bHLH-PAS proteins involved in sensing and coordinating transcriptional responses to xenobiotics, hypoxia, and developmental pathways. Although its C-terminal transactivation domain is dispensable for transcriptional activation in vivo, ARNT has recently been shown to use its N-terminal bHLH and/or PAS domains to interact with several transcriptional coactivators that are required for transcriptional initiation after xenobiotic or hypoxic cues. Here we show that ARNT uses a single PAS domain to interact with two coiled coil coactivators, TRIP230 and CoCoA. Both coactivators interact with the same interface on the ARNT PAS-B domain, located on the opposite side of the domain used to associate with the analogous PAS domain on its heterodimeric bHLH-PAS partner HIF-2α. Using NMR and biochemical studies, we identified the ARNT-interacting motif of one coactivator, TRIP230 as an LXXLL-like nuclear receptor box. Mutation of this motif and proximal sequences disrupts the interaction with ARNT PAS-B. Identification of this ARNT-coactivator interface illustrates how ARNT PAS-B is used to form critical interactions with both bHLH-PAS partners and coactivators that are required for transcriptional responses.
- Published
- 2009
23. NMR structures of the selenoproteins Sep15 and SelM reveal redox activity of a new thioredoxin-like family
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Vadim N. Gladyshev, Dmitri E. Fomenko, Vyacheslav M. Labunskyy, Demet Araç, Josep Rizo, Carlos A. Amezcua, Andrew D. Ferguson, Yogarany Chelliah, and Johann Deisenhofer
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Male ,Models, Molecular ,Magnetic Resonance Spectroscopy ,Protein family ,Cell Survival ,Protein Conformation ,SEP15 ,Amino Acid Motifs ,Molecular Sequence Data ,chemistry.chemical_element ,Biochemistry ,chemistry.chemical_compound ,Mice ,Selenium ,Protein structure ,Thioredoxins ,Oxidoreductase ,Escherichia coli ,Animals ,Drosophila Proteins ,Amino Acid Sequence ,Sulfhydryl Compounds ,Selenoproteins ,Molecular Biology ,chemistry.chemical_classification ,Mice, Inbred BALB C ,Binding Sites ,Selenocysteine ,Endoplasmic reticulum ,Cell Biology ,Recombinant Proteins ,Oxidative Stress ,Drosophila melanogaster ,chemistry ,NIH 3T3 Cells ,Insect Proteins ,RNA Interference ,Selenoprotein ,Oxidation-Reduction - Abstract
Selenium has significant health benefits, including potent cancer prevention activity and roles in immune function and the male reproductive system. Selenium-containing proteins, which incorporate this essential micronutrient as selenocysteine, are proposed to mediate the positive effects of dietary selenium. Presented here are the solution NMR structures of the selenoprotein SelM and an ortholog of the selenoprotein Sep15. These data reveal that Sep15 and SelM are structural homologs that establish a new thioredoxin-like protein family. The location of the active-site redox motifs within the fold together with the observed localized conformational changes after thiol-disulfide exchange and measured redox potential indicate that they have redox activity. In mammals, Sep15 expression is regulated by dietary selenium, and either decreased or increased expression of this selenoprotein alters redox homeostasis. A physiological role for Sep15 and SelM as thiol-disulfide oxidoreductases and their contribution to the quality control pathways of the endoplasmic reticulum are discussed.
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- 2005
24. NMR Characterization of an Oligonucleotide Model of the MiR-21 Pre-Element
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Qiong Wu, Carlos A. Amezcua, Sara Chirayil, and Kevin J. Luebke
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Models, Molecular ,Base pair ,Stereochemistry ,Molecular Sequence Data ,Oligonucleotides ,lcsh:Medicine ,Guanosine ,Biochemistry ,chemistry.chemical_compound ,Nucleic Acids ,RNA stem-loop structure ,RNA folding ,Nucleic acid structure ,lcsh:Science ,RNA structure ,Nuclear Magnetic Resonance, Biomolecular ,Protein secondary structure ,Multidisciplinary ,Base Sequence ,Biology and life sciences ,Oligonucleotide ,lcsh:R ,Nuclear magnetic resonance spectroscopy ,Stem-loop ,Uridine ,RNA structure determination ,MicroRNAs ,RNA processing ,chemistry ,Nucleic Acid Conformation ,RNA ,lcsh:Q ,Research Article - Abstract
We have used NMR spectroscopy to characterize an oligonucleotide stem loop structure based on the pre-element of an oncogenic microRNA, miR-21. This predicted stem-loop structure is cleaved from the precursor of miR-21 (pre-miR-21) by the nuclease Dicer. It is also a critical feature recognized by the protein complex that converts the primary transcript (pri-miR-21) into the pre-miRNA. The secondary structure of the native sequence is poorly defined by NMR due to rapid exchange of imino protons with solvent; however, replacement of two adjacent putative G•U base pairs with G•C base pairs retains the conformation of the hairpin observed by chemical probing and stabilizes it sufficiently to observe most of the imino proton resonances of the molecule. The observed resonances are consistent with the predicted secondary structure. In addition, a peak due to a loop uridine suggests an interaction between it and a bulged uridine in the stem. Assignment of non-exchangeable proton resonances and characterization of NOEs and coupling constants allows inference of the following features of the structure: extrahelicity of a bulged adenosine, deviation from A-form geometry in a base-paired stem, and consecutive stacking of the adenosines in the 5' side of the loop, the guanosine of the closing base pair, and a cross-strand adenosine. Modeling of the structure by restrained molecular dynamics suggests a basis for the interaction between the loop uridine, the bulged uridine in the stem, and an A•U base pair in the stem.
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- 2014
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25. Biodisponibilidad de lisina en dos pastas de soya con diferente nivel de actividad ureásica en pollos de engorda
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Gabriela Gómez Verduzco, Carlos Martínez Amezcua, Carlos López Coello, Ernesto Ávila González, and Arturo Cortés Cuevas
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Multiple regression equation ,lcsh:Veterinary medicine ,General Veterinary ,Par ámetros productivos ,Actividad ureásica ,complex mixtures ,Pasta de soya ,Animal science ,Biochemistry ,Biodisponbilidad de lisina ,lcsh:SF600-1100 ,bacteria ,Animal Science and Zoology ,lcsh:Animal culture ,Veterinaria ,Pollo de engorda ,lcsh:SF1-1100 ,Mathematics - Abstract
In order to study bioavailability of lysine of two soybeans meals (PSA and PSB) for broilers with different ureaseactivity (UA of 0.11 and 0.17 units of pH change), an experiment was performed. Two hundred and ten (210) chicksRoss were used from 1 to 21 d of age, in a completely randomized design with 7 treatments with three replicateseach one. Treatments were: 1) Basal diet sorghum-soybean meal (deficient in lysine), 2) Basal diet+0.05% L-lysine,3) Basal diet+0.10% L-lysine, 4) Basal diet+0.05% lysine from PSA, 5) Basal diet+0.10% lysine from PSA, 6) Basaldiet+0.05% lysine from PSB and 7) Basal diet+0.10% lysine from PSB. The growth results obtained were explainedby multiple linear regression equation, based on the data of weight gain, consumption of synthetic lysine and intakesof lysine from soybean meals: Y=X1+ Y= 375.419 + 0.0378 X1 + 0.0366 X2 + 0.0376 X3; where X1 accountedsupplementation with L-lysine, X2 with PSA (with addition of raw hull) and X3 with PSB (with addition of cockedhull). Comparison of the PSA or PSB slopes with the L-lysine slope (i.e. 100 % bioavailability) showed them all tohave >95 % lysine availability: PS A= 97 %, PSB= 99 %. These results indicate that UA of soybean meal affectedthe bioavailability of lysine; therefore more than 0.12 urcase activity units of pH change, lower is the availability.
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- 2014
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26. Necesidades de treonina en pollos sometidos a dos calendarios de vacunación
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René Morales López, Tomás Jínez Méndez, Ernesto Ávila González, and Carlos Martínez Amezcua
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TREONINA ,ESTRÉS ,NECESIDADES ,POLLOS DE ENGORDA ,Veterinaria ,INMUNIDAD - Abstract
El presente estudio tuvo como propósito investigar si la necesidad de treonina en la dieta no se incrementa al someter a pollos de engorda a un calendario cerrado de vacunación, manejo que representa mayor estrés. Se realizó un experimento con 990 pollos de engorda Arbor Acres, mixtos, de 1 a 42 días de edad, utilizando seis tratamientos con cinco repeticiones de 33 pollos cada uno. Se utilizó un diseño completamente al azar con un arreglo factorial 3 × 2; tres niveles de treonina en función del requerimiento informado por el NRC 1994 (95%, 100% y 105%) y dos programas de vacunación [abierto: Dos vacunas de Newcastle y cerrado; dos vacunas de Newcastle, una de infección de la Bolsa de Fabricio (IBF) y una bacterina de E. coli]. Se emplearon dietas en base a sorgo más pasta de soya para iniciación y finalización, con L-treonina para lograr los niveles requeridos. Los resultados en 42 días para ganancia de peso, consumo de alimento, conversión alimentaria, mortalidad general y resultados séricos de los títulos de anticuerpos por la prueba de inhibición de la hemoaglutinación para la enfermedad de Newcastle, no indicaron diferencias estadísticas (P 0.05) entre tratamientos. Los resultados de este estudio sugieren que las necesidades de treonina al 95% de lo que señala el NRC en 1994, son adecuadas para óptimo comportamiento productivo e inmunidad de pollos de engorda.
- Published
- 2001
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