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Parage B, Miqueu C, Pérez-Rodríguez M, Méndez-Morales T, Piñeiro MM. Upper storage-capacity limit and multiple occupancy phenomena in H 2-hydroquinone clathrates using Monte Carlo and DFT simulations. Phys Chem Chem Phys 2024; 26:6939-6948. [PMID: 38334443 DOI: 10.1039/d3cp05331h] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/10/2024]
Abstract
The upper hydrogen-storage capacity limit of the β-hydroquinone clathrate has been investigated using hybrid Grand-Canonical Monte Carlo/Molecular Dynamics simulations, for temperatures ranging from 77 K to 300 K. The evolution with pressure of the cage occupancies has been monitored in detail, describing the progressive nature of the uptake process. It is found that the storage capacity of the pure β-HQ + H2 clathrate could reach 0.6 wt% (weight percentage) only for pressures above 1400 bar, at ambient temperature. The enhancement of the storage capacities by the multiple occupancy phenomenom was accordingly shown to be very limited by the need for extreme conditions. Following this observation, an unmodified version of the van der Waals & Platteeuw theory was applied allowing for the prediction of experimentally accessible formation pressures. Density functional theory calculations were addittionnaly performed to comprehensively characterize the hydrogen diffusion process within the clathrate crystalline structure, considering different occupancy scenarios.
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Affiliation(s)
- B Parage
- Universidade de Vigo, Departamento de Física Aplicada, E-36310, Vigo, Spain.
- Laboratoire des Fluides Complexes et leurs Réservoirs, UMR 5150, Université de Pau et des Pays de l'Adour, 64600, Anglet, France
| | - C Miqueu
- Laboratoire des Fluides Complexes et leurs Réservoirs, UMR 5150, Université de Pau et des Pays de l'Adour, 64600, Anglet, France
| | - M Pérez-Rodríguez
- Universidade de Vigo, Departamento de Física Aplicada, E-36310, Vigo, Spain.
| | - T Méndez-Morales
- Grupo de Nanomateriais, Fotónica e Materia Branda, Departamento de Física de Partículas, Universidade de Santiago de Compostela, Campus Vida s/n E-15782, Spain
| | - M M Piñeiro
- Universidade de Vigo, Departamento de Física Aplicada, E-36310, Vigo, Spain.
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Osvaldo Talavera J, Roy-García I, Díaz-Torres ST, Palacios-Cruz L, Noguez-Ramos A, Pérez-Rodríguez M, Martínez MÁ, Silva-Guzmán JE, Rivas-Ruiz R. [Numerical expression of the clinical course of the disease. Data management]. Rev Med Inst Mex Seguro Soc 2023; 61:S503-S509. [PMID: 37935026 PMCID: PMC10756149 DOI: 10.5281/zenodo.8319834] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Subscribe] [Scholar Register] [Received: 01/13/2023] [Accepted: 02/15/2023] [Indexed: 11/09/2023]
Abstract
Data management "behind the scenes" refers to collection, cleaning, imputation, and demarcation; and despite of being indispensable processes, they are usually neglected and thus, generate erroneous information. During the collection are errors: omission of covariates, deviation from the objective, and insufficient quality. The omission of covariates distorts the result attributed to the main manoeuvre. Deviation from the primary objective commonly occurs when the outcome is rare, delayed, or subjective and promotes substitution by non-equivalent surrogate variables. Moreover, insufficient quality occurs due to inadequate instruments, omission of the measurement procedure, or measurements out of context, such as attribution at the wrong time or equivalent. Furthermore, cleaning implies identifying erroneous, extreme, and missing values, which may or may not be imputed, depending on the percentage. The values of the manoeuvre or the outcome are never imputed, nor are patients eliminated due to a lack of values. Finally, the demarcation of each variable seeks to give it a clinical meaning about the outcome, for which a hierarchical sequence of criteria is followed: 1) previous clinical study, 2) expert agreement, 3) clinical judgment of the investigator/investigators, and 4) statistics. Acting without quality controls in data management frequently causes involuntary lies and confuses instead of clarifying.
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Affiliation(s)
- Juan Osvaldo Talavera
- Centro Médico ABC, Subdirección de Enseñanza e Investigación. Ciudad de México, MéxicoCentro Médico ABCMéxico
| | - Ivonne Roy-García
- Instituto Mexicano del Seguro Social, Coordinación de Investigación en Salud, Centro de Adiestramiento en Investigación Clínica. Ciudad de México, MéxicoInstituto Mexicano del Seguro SocialMéxico
| | - Sofía Teresa Díaz-Torres
- Centro Médico ABC, Subdirección de Enseñanza e Investigación. Ciudad de México, MéxicoCentro Médico ABCMéxico
| | - Lino Palacios-Cruz
- Instituto Nacional de Psiquiatría Dr. Ramón de la Fuente. Subdirección de Investigaciones Clínicas, Departamento de Epidemiología Clínica. Ciudad de México, MéxicoInstituto Mexicano del Seguro SocialMéxico
| | - Alejandro Noguez-Ramos
- Centro Médico ABC, Subdirección de Enseñanza e Investigación. Ciudad de México, MéxicoCentro Médico ABCMéxico
| | - Marcela Pérez-Rodríguez
- Instituto Mexicano del Seguro Social, Coordinación de Investigación en Salud, Centro de Adiestramiento en Investigación Clínica. Ciudad de México, MéxicoInstituto Mexicano del Seguro SocialMéxico
| | - Miguel Ángel Martínez
- Centro Médico ABC, Subdirección de Enseñanza e Investigación. Ciudad de México, MéxicoCentro Médico ABCMéxico
| | - Jessica E. Silva-Guzmán
- Centro Médico ABC, Subdirección de Enseñanza e Investigación. Ciudad de México, MéxicoCentro Médico ABCMéxico
| | - Rodolfo Rivas-Ruiz
- Instituto Mexicano del Seguro Social, Coordinación de Investigación en Salud, Centro de Adiestramiento en Investigación Clínica. Ciudad de México, MéxicoInstituto Mexicano del Seguro SocialMéxico
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Varela-Vega Y, Roy-García IA, Pérez-Rodríguez M, Velázquez-López L. [Diagnostic performance of the FINDRISC questionnaire to identify insulin resistance in adults]. Rev Med Inst Mex Seguro Soc 2023; 61:33-41. [PMID: 36542467 PMCID: PMC10395935] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Subscribe] [Scholar Register] [Received: 03/10/2022] [Accepted: 08/01/2022] [Indexed: 12/24/2022]
Abstract
Background Insulin resistance (IR) is a state prior to the development of type 2 diabetes (T2D) and it is reversible with lifestyle modification. However, it is underdiagnosed due to the difficulty in its measurement. Objective To evaluate the diagnostic performance of the FINDRISC questionnaire to identify IR. Material and methods An analytical cross-sectional study was performed in adults aged 20 to 60 years without previous diagnosis of T2D. Those using steroids and pregnant women were excluded. IR was diagnosed through the Triglycerides/glucose index. A ROC curve was used to establish the cut-off point for the diagnosis of IR. Sensitivity, specificity, predictive values and likelihood ratios were calculated. Risk measurement for IR was performed with the FINDRISC instrument. Results A total of 253 participants were included, with a prevalence of IR of 60.8%. The area under the curve of the FINDRISC instrument was 0.813 (95% confidence interval [95% CI] 0.759-0.865), with a cut-off point of 8. Sensitivity was 94.8% and specificity was 48.5%, positive predictive value was 74% and negative 86%, with a positive likelihood ratio of 1.84 and a negative of 0.11. Conclusions The FINDRISC instrument is a useful screening tool to identify subjects with IR at the first level of care. A score ≥ 8 identifies subjects with IR.
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Affiliation(s)
- Yuline Varela-Vega
- Instituto Mexicano del Seguro Social, Unidad de Medicina Familiar No. 28, Servicio de Consulta Externa. Ciudad de México, México
| | - Ivonne Analí Roy-García
- Instituto Mexicano del Seguro Social, Centro Médico Nacional Siglo XXI, Coordinación de Investigación en Salud, División de Investigación Clínica. Ciudad de México, México
| | - Marcela Pérez-Rodríguez
- Instituto Mexicano del Seguro Social, Centro Médico Nacional Siglo XXI, Coordinación de Investigación en Salud, División de Investigación Clínica. Ciudad de México, México
| | - Lubia Velázquez-López
- Instituto Mexicano del Seguro Social, Hospital General Regional No. 1 "Dr. Carlos Mac Gregor Sánchez Navarro", Unidad de Investigación. Ciudad de México, México
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Blachman-Braun R, Talavera JO, Pérez-Rodríguez M, Roy-García I, Rivas-Ruiz R, Huitrón-Bravo G, Salmerón J. Risk Assessment of Dyslipidemias, Hyperglycemia, Hyperuricemia, and Hypertension Utilizing Self-Reported Body Silhouettes. J Obes 2023; 2023:4991684. [PMID: 37025979 PMCID: PMC10072955 DOI: 10.1155/2023/4991684] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/22/2022] [Revised: 03/02/2023] [Accepted: 03/14/2023] [Indexed: 03/30/2023] Open
Abstract
OBJECTIVE Self-reported body silhouette is an anthropometric instrument that has been utilized as a screening tool for underweight, overweight, obesity, and other abnormal anthropometric variables. Herein, we analyzed the risk associated with the self-reported body silhouette in the scope of dyslipidemias, hyperglycemia, hyperuricemia, and hypertension. METHODS Adult participants of the Health Workers Cohort Study enrolled between March 2004 and April 2006 were included. Then, risk analysis was performed considering dyslipidemias as serum triglycerides, high total cholesterol, high LDL-C, low HDL-C, hyperglycemia, hyperuricemia, and hypertension. RESULTS A total of 2,297 males and 5,003 females were analyzed. The median ages of the studied population was 39 (30-49) and 41 (31-50) years for males and females, respectively. Overall, there is a stepwise increase in the risk of presenting dyslipidemias, hyperglycemia, hyperuricemia, and hypertension as the self-reported body silhouette number increases, this tendency was observed in both males and females. CONCLUSION Self-reported body silhouette is a useful risk assessment tool for dyslipidemias, hyperglycemia, hyperuricemia, and hypertension in Mexican adults. Applications of questioners containing this silhouette might be considered a valuable public health instrument due to their low cost, relative simplicity, and absence of specialized equipment, training, or respondent knowledge.
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Affiliation(s)
- Ruben Blachman-Braun
- Department of Urology, University of Miami Miller School of Medicine, Miami, FL, USA
- Training and Clinical Research Center, Specialty Hospital, Mexican Social Security Institute, National Medical Center XXI, Mexico City, Mexico
| | | | - Marcela Pérez-Rodríguez
- Training and Clinical Research Center, Specialty Hospital, Mexican Social Security Institute, National Medical Center XXI, Mexico City, Mexico
| | - Ivonne Roy-García
- Training and Clinical Research Center, Specialty Hospital, Mexican Social Security Institute, National Medical Center XXI, Mexico City, Mexico
| | - Rodolfo Rivas-Ruiz
- Training and Clinical Research Center, Specialty Hospital, Mexican Social Security Institute, National Medical Center XXI, Mexico City, Mexico
| | - Gerardo Huitrón-Bravo
- Faculty of Medicine, Autonomous University of the State of Mexico, Toluca, State of Mexico, Mexico
| | - Jorge Salmerón
- Center for Research in Policies, Population and Health, National Autonomous University of Mexico, Mexico City, Mexico
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Blachman-Braun R, Talavera JO, Pérez-Rodríguez M, Roy-García I, Rivas-Ruiz R, Huitrón-Bravo G, Salmerón-Castro J. Self-reported body silhouettes: a diagnostic instrument for anthropometric parameters. Public Health 2021; 200:39-46. [PMID: 34662752 DOI: 10.1016/j.puhe.2021.09.001] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2021] [Revised: 08/15/2021] [Accepted: 09/03/2021] [Indexed: 11/30/2022]
Abstract
OBJECTIVE Routine body size measurement of anthropometric values requires professionals, standardized techniques, and calibrated tools. Therefore, there is a need for easier screening tools such as the self-reported body silhouette (Self-bosi). The aim of this study was to analyze the performance of Self-bosi as a proxy of anthropometric values. STUDY DESIGN Prospective analytic study of the Health Workers Cohort Study. METHODS Adult participants of the Health Workers Cohort Study were included. Then, through the calculation sensitivity and specificity of Self-bosi to detect abnormal waist circumference (WC) (≥90 cm for male and ≥80 cm for female participants), elevated body fat percentage (BF%) (≥25% for male and ≥35% for female participants), as well as overweight and obesity (≥25 kg/m2) and obesity (≥30 kg/m2). RESULTS A total of 2471 male and 5940 female participants were analyzed. Overall, Self-bosi discriminate high WC values (area under the curve [AUC]; male participants: 0.80, female participants: 0.82); increased BF% (AUC: male participants: 0.78, female participants: 0.83); overweight and obesity (AUC: male participants: 0.81, female participants: 0.86); and obesity (AUC: male participants: 0.83, female participants: 0.89). CONCLUSION Self-bosi is an accurate method to assess increased WC, BF%, obesity, and overweight-obesity in Mexican adults. Given its simplicity and low-cost of the self-reported body silhouette, it might be considered a useful anthropometric screening instrument in large scale epidemiological research.
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Affiliation(s)
- R Blachman-Braun
- Centro de Adiestramiento e Investigación Clínica, Hospital de Especialidades CMN SXXI, Instituto Mexicano del Seguro Social, Ciudad de México, México; Department of Urology, University of Miami, Miller School of Medicine, Miami, FL, USA
| | - J O Talavera
- Jefatura de Enseñanza, Centro Médico ABC, Ciudad de México, México.
| | - M Pérez-Rodríguez
- Centro de Adiestramiento e Investigación Clínica, Hospital de Especialidades CMN SXXI, Instituto Mexicano del Seguro Social, Ciudad de México, México
| | - I Roy-García
- Centro de Adiestramiento e Investigación Clínica, Hospital de Especialidades CMN SXXI, Instituto Mexicano del Seguro Social, Ciudad de México, México
| | - R Rivas-Ruiz
- Centro de Adiestramiento e Investigación Clínica, Hospital de Especialidades CMN SXXI, Instituto Mexicano del Seguro Social, Ciudad de México, México
| | - G Huitrón-Bravo
- Facultad de Medicina, Universidad Autónoma del Estado de México, Toluca, Estado de México, México
| | - J Salmerón-Castro
- Centro de Investigación en Políticas, Población y Salud, Universidad Nacional Autónoma de México, Ciudad de México, México
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Rivas-Ruiz R, Roy-García I, Pérez-Rodríguez M, Berea R, Moreno-Palacios J, Moreno-Noguez M, Palacios-Cruz L, Ureña-Wong KR. [The relevance and irrelevance of charts in clinical research]. ACTA ACUST UNITED AC 2021; 67:381-396. [PMID: 33631905 DOI: 10.29262/ram.v67i4.854] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
Abstract
Charts are a visual aid that is used in articles in order to highlight the results of an investigation. They allow illustrating the results with the purpose of making them clearer. Charts, just like statistical tests, are selected based on the objective of the study, the types of variable, and the statistical analyzes to be illustrated. Some of the most commonly used charts in clinical practice are frequency histograms, which illustrate qualitative variables or frequencies; also error charts, that are used for normally distributed quantitative variables; box plots or violin plots are used for distribution-free quantitative variables, and survival curves are for variables that include the person-time variable. The aforementioned charts can be used to illustrate the comparisons between maneuvers and outcome depending on the type of variable that is being analyzed. When two groups are compared and the dependent variable is dichotomous, forest plots are used; for multivariate models, the chart depends on the type of analysis. As for logistic regression and linear regression, tree diagrams are used; and scatter plots are used for linear regression. Survival plots are used for Cox proportional hazards. Although charts can be very useful, if they are misused, they can show differences where there are none, which leads to a misinterpretation of the studies. In this article, we will use examples to complement the topics that were previously addressed in the articles of this series.
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Affiliation(s)
- Rodolfo Rivas-Ruiz
- Instituto Mexicano del Seguro Social, Coordinación de Investigación en Salud, División de Desarrollo de la Investigación, Ciudad de México, México.
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Talavera JO, Roy-García IA, Pérez-Rodríguez M, Palacios-Cruz L, Rivas-Ruíz R. Back to the clinic. Methods II. The Architecture of Clinical Research. Subject interaction, maneuvers and disease throughout time. GAC MED MEX 2020; 156:430-438. [PMID: 33372925 DOI: 10.24875/gmm.m20000433] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022] Open
Abstract
Medicine is characterized by the application of the scientific method through clinical judgment, by correct interpretation and use of the clinical course and/or natural history of the disease; its best description is observed in the architecture of clinical research. Through a temporal sequence, this model explains the phenomenon of causality with three sections: baseline status, maneuver, and outcome. The baseline status assesses who the patient is, where does he come from, his general conditions, the diagnosis, stage and aggressiveness of the pathology, complications, previous therapies, socioeconomic-cultural level, habits, therapeutic indications or contraindications, and the expected evolution is anticipated. In the maneuver, risk or prognostic factors, specific or symptomatic treatment, and general measures can be evaluated. In the outcome, early and late evolution are monitored. The model also allows the causes of follow-up loss to be determined. Anticipating patient evolution by recognizing his condition, disease, and expected effect of medical decisions allows acting in advance, since waiting for the manifestations of the evolutionary process of disease results in detriment to the patient.
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Affiliation(s)
- Juan O Talavera
- Directorate of Teaching and Research, Centro Médico ABC. Mexico City, Mexico
| | - Ivonne A Roy-García
- Clinical Research Training Center, Centro Médico Nacional Siglo XXI, Instituto Mexicano del Seguro Social. Mexico City, Mexico
| | - Marcela Pérez-Rodríguez
- Clinical Research Training Center, Centro Médico Nacional Siglo XXI, Instituto Mexicano del Seguro Social. Mexico City, Mexico
| | - Lino Palacios-Cruz
- Department of Clinical Epidemiology, Sub-directorate of Clinical Research, Instituto Nacional de Psiquiatría "Dr. Ramón de la Fuente", Secretaría de Salud. Mexico City, Mexico
| | - Rodolfo Rivas-Ruíz
- Clinical Research Training Center, Centro Médico Nacional Siglo XXI, Instituto Mexicano del Seguro Social. Mexico City, Mexico
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Talavera JO, Roy-García I, Pérez-Rodríguez M, Palacios-Cruz L, Rivas-Ruiz R. De vuelta a la clínica. Métodos II. Arquitectura de la investigación clínica. Interacción sujeto, maniobras y enfermedad a través del tiempo. GAC MED MEX 2020. [DOI: 10.24875/gmm.20000159] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022] Open
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Talavera JO, Roy-García I, Palacios-Cruz L, Rivas-Ruiz R, Hoyo I, Pérez-Rodríguez M. Back to the clinic. Methods I. Research designs. Higher quality of information, more certainty to the answer. GAC MED MEX 2020. [DOI: 10.24875/gmm.m19000304] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022] Open
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Abstract
The concept of correlation entails having a couple of observations (X and Y), that is to say, the value that Y acquires for a determined value of X; the correlation makes it possible to examine the trend of two variables to be grouped together. We know that, with increasing age, blood pressure figures also increase, therefore, if we want to answer a research question like "what is the connection between age and blood pressure?" the relevant statistical test is a correlation test. This test makes it possible to quantify the magnitude of the correlation between two variables, but it is also helpful for predicting values. If these variables had a perfect correlation, the value of the variable Y could be deduced by knowing the value of X. Because of these advantages, the correlation is one of the most frequently used tests in the clinical setting since, in addition to measuring the direction and magnitude of the association of two variables, it is one of the foundations for prediction models, such as linear regression model, logistic regression model and Cox proportional hazards model.
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Affiliation(s)
- Ivonne Roy-García
- Instituto Mexicano del Seguro Social, Centro Médico Nacional Siglo XXI, Centro de Adiestramiento en Investigación Clínica, Ciudad de México, México.
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Talavera JO, Rivas-Ruiz R, Pérez-Rodríguez M, Roy-Garcia IA, Palacios-Cruz L. Back to the clinic: without a rationale there is no worthy research question. GAC MED MEX 2019. [DOI: 10.24875/gmm.m19000250] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022] Open
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Pérez-Rodríguez M, Cano A, Durán U, Barrios JA. Solubilization of organic matter by electrochemical treatment of sludge: Influence of operating conditions. J Environ Manage 2019; 236:317-322. [PMID: 30738302 DOI: 10.1016/j.jenvman.2019.01.105] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/07/2018] [Revised: 01/09/2019] [Accepted: 01/27/2019] [Indexed: 06/09/2023]
Abstract
Sludge generated after wastewater treatment represents an important challenge due to the large amounts produced and the need to adequately treat it. Anaerobic digestion is the preferred treatment process to obtain renewable energy as well as a biosolid with the potential to be reused in land application. This process generates biogas (methane and carbon dioxide) that may be used for energy co-generation. However, anaerobic digestion is limited by the hydrolysis step since bacteria need to break down organic matter and large molecules to allow conversion into biogas. In this study, electrochemical treatment of sludge is proposed to solubilize organic matter. Boron-doped diamond electrodes were used to treat waste activated sludge under different experimental conditions (current density, flow rate, time) to evaluate their influence on the solubilization of organic matter (in terms of chemical oxygen demand). The degree of solubilization ranged between 0.31 and 1.78%. Based on the results, optimal operating conditions were current density of 19.3 mA cm-2, flow rate of 4 L min-1, and treatment time of 30 min. Furthermore, treatment flow rate was found to play a key role in solubilization, as the process is controlled by mass transfer.
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Affiliation(s)
- M Pérez-Rodríguez
- Instituto de Ingeniería UNAM, Circuito Escolar, Ciudad Universitaria, 04510 México, D.F., Mexico
| | - A Cano
- Tecnológico de Monterrey, Escuela de Ingeniería y Ciencias, Ave. Eugenio Garza Sada 2501, 64849 Monterrey, N.L., Mexico
| | - U Durán
- Instituto de Ingeniería UNAM, Circuito Escolar, Ciudad Universitaria, 04510 México, D.F., Mexico
| | - J A Barrios
- Instituto de Ingeniería UNAM, Circuito Escolar, Ciudad Universitaria, 04510 México, D.F., Mexico.
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Talavera JO, Roy-García I, Palacios-Cruz L, Rivas-Ruiz R, Hoyo I, Pérez-Rodríguez M. De vuelta a la clínica. Métodos I. Diseños de investigación. Mayor calidad de información, mayor certeza a la respuesta. GAC MED MEX 2019; 155:399-405. [PMID: 31486784 PMCID: PMC7446753 DOI: 10.24875/gmm.19005226] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/15/2019] [Accepted: 05/17/2019] [Indexed: 11/17/2022] Open
Abstract
Research designs refer to the way information is obtained and are limited by ethical, economic and temporal viability. Research designs are standardized strategies to reduce biases, which in the architectural model of research are identified in the baseline state, the maneuver and the outcome; hence, there are no specific designs for each question. The design with the lowest probability of bias is the clinical trial, followed by cohort and case-control studies and, finally, by cross-sectional surveys. Among the main characteristics that give merit to research designs are the following: population inquiry, which refers to the situation of the population in relation to the clinical course/natural history of the disease; the maneuver, or action that is expected to modify the baseline state, which can be observational or experimental; follow-up, or documented monitoring that is given to each subject, which can be longitudinal or cross-sectional; and directionality, which can prolective or retrolective and refers to the timing of data collection for research purposes. It will always be better having a valuable question, even when answered with a design with higher risk of bias, than a question that is irrelevant or has no applicability.
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Affiliation(s)
| | - Ivonne Roy-García
- Instituto Mexicano del Seguro Social, Coordinación de Investigación en Salud, Centro Médico Nacional Siglo XXI, Centro de Adiestramiento en Investigación Clínica
| | - Lino Palacios-Cruz
- Instituto Nacional de Psiquiatría “Dr. Ramón de la Fuente”, Subdirección de Investigaciones Clínicas, Departamento Epidemiología Clínica
| | - Rodolfo Rivas-Ruiz
- Instituto Mexicano del Seguro Social, Coordinación de Investigación en Salud, Centro Médico Nacional Siglo XXI, Centro de Adiestramiento en Investigación Clínica
| | - Irma Hoyo
- Servicio de Medicina Interna, Centro Médico ABC. Ciudad de México
| | - Marcela Pérez-Rodríguez
- Instituto Mexicano del Seguro Social, Coordinación de Investigación en Salud, Centro Médico Nacional Siglo XXI, Centro de Adiestramiento en Investigación Clínica
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Talavera JO, Rivas-Ruiz R, Pérez-Rodríguez M, Roy-Garcia IA, Palacios-Cruz L. De vuelta a la clínica: sin justificación no existe pregunta de investigación que valga. GAC MED MEX 2019; 155:168-175. [PMID: 31056591 PMCID: PMC7446752 DOI: 10.24875/gmm.19004942] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2018] [Accepted: 01/16/2019] [Indexed: 12/12/2022] Open
Abstract
A clinical research question requires the concurrence of clinical experience and knowledge on methodology and statistics in that who formulates it. Initially, a research question should have a structure that clearly establishes what is that which is being sought (consequence or outcome), in whom (baseline status), and by action of what (maneuver). Subsequently, its reasoning must explore four aspects: feasibility and reasonableness of the questioning, lack of a prior answer, relevance of the answer to be obtained, and applicability. Once these aspects are satisfactorily covered, the question can be regarded as being "clinically relevant", which is different from being statistically significant, which refers to the probability of the result being driven by chance, which does not reflect the relevance of the question or the outcome. One should never forget that every maneuver entails adverse events that, when serious, discredit good results. It is imperative to have the possible answer estimated from within the structure of the question. The function of clinical research is to corroborate or reject a hypothesis, rather than to empirically test to find out what the outcome is.
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Affiliation(s)
- Juan O Talavera
- Dirección de Enseñanza e Investigación, Centro Médico ABC. Ciudad de México, México
| | - Rodolfo Rivas-Ruiz
- Instituto Mexicano del Seguro Social, Coordinación de Investigación en Salud, Centro Médico Nacional Siglo XXI, Centro de Adiestramiento en Investigación Clínica. Ciudad de México, México
| | - Marcela Pérez-Rodríguez
- Instituto Mexicano del Seguro Social, Coordinación de Investigación en Salud, Centro Médico Nacional Siglo XXI, Centro de Adiestramiento en Investigación Clínica. Ciudad de México, México
| | - Ivonne Analí Roy-Garcia
- Instituto Mexicano del Seguro Social, Coordinación de Investigación en Salud, Centro Médico Nacional Siglo XXI, Centro de Adiestramiento en Investigación Clínica. Ciudad de México, México
| | - Lino Palacios-Cruz
- Secretaría de Salud, Instituto Nacional de Psiquiatría "Dr. Ramón de la Fuente", Subdirección de Investigaciones Clínicas, Departamento Epidemiología Clínica. Ciudad de México, México
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Fernández-Fernández A, Pérez-Rodríguez M, Comesaña A, Piñeiro M. Three-phase equilibrium curve shift for methane hydrate in oceanic conditions calculated from Molecular Dynamics simulations. J Mol Liq 2019. [DOI: 10.1016/j.molliq.2018.10.146] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
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Comesaña A, Pérez-Rodríguez M, Fernández-Fernández AM, Piñeiro MM. A description of hydroquinone clathrates using molecular dynamics: Molecular model and crystalline structures for CH4and CO2guests. J Chem Phys 2018; 148:244502. [PMID: 29960310 DOI: 10.1063/1.5027807] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023] Open
Affiliation(s)
- A. Comesaña
- Universidade de Vigo, Departamento de Física Aplicada, Campus Lagoas-Marcosende, E36310 Vigo, Spain
| | - M. Pérez-Rodríguez
- Universidade de Vigo, Departamento de Física Aplicada, Campus Lagoas-Marcosende, E36310 Vigo, Spain
| | | | - M. M. Piñeiro
- Universidade de Vigo, Departamento de Física Aplicada, Campus Lagoas-Marcosende, E36310 Vigo, Spain
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Hermida-Merino C, Pérez-Rodríguez M, Piñeiro MM, Pastoriza-Gallego MJ. Tuning the electrical conductivity of exfoliated graphite nanosheets nanofluids by surface functionalization. Soft Matter 2017; 13:3395-3403. [PMID: 28429007 DOI: 10.1039/c7sm00218a] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/04/2023]
Abstract
The electrical conductivity of exfoliated graphite in water nanofluids has been experimentally determined, and compared with the same property when the dispersed nanosheets have been oxidized. The effect of oxidation on this property is different if compared with the case of sintered dry nanosheets. In any case, for the sintered raw material the conduction behaves as expected in a metal, while for the nanofluid it shows values and trends typical of a weak electrolyte solution. The effect of oxidation on the electrical conductivity of exfoliated graphite can be explained as being caused by the dissociation in the fluid phase of the moieties resulting from the chemical functionalization process. This opens the possibility of designing a functionalization process to tune the nanofluid electrical conductivity.
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Affiliation(s)
- C Hermida-Merino
- Departamento de Física Aplicada, Universidade de Vigo, E36310, Spain.
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Pérez-Rodríguez M, Vidal-Vidal A, Míguez JM, Blas FJ, Torré JP, Piñeiro MM. Computational study of the interplay between intermolecular interactions and CO 2 orientations in type I hydrates. Phys Chem Chem Phys 2017; 19:3384-3393. [PMID: 28092383 DOI: 10.1039/c6cp07097c] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
Carbon dioxide (CO2) molecules show a rich orientation landscape when they are enclathrated in type I hydrates. Previous studies have described experimentally their preferential orientations, and some theoretical works have explained, but only partially, these experimental results. In the present paper, we use classical molecular dynamics and electronic density functional theory to advance in the theoretical description of CO2 orientations within type I hydrates. Our results are fully compatible with those previously reported, both theoretical and experimental, the geometric shape of the cavities in hydrate being, and therefore, the steric constraints, responsible for some (but not all) preferential angles. In addition, our calculations also show that guest-guest interactions in neighbouring cages are a key factor to explain the remaining experimental angles. Besides the implication concerning equation of state hydrate modeling approximations, the conclusion is that these guest-guest interactions should not be neglected, contrary to the usual practice.
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Affiliation(s)
- M Pérez-Rodríguez
- Dpto. de Física Aplicada, Fac. de Ciencias, Univ. de Vigo, E36310, Spain.
| | - A Vidal-Vidal
- Dpto. de Física Aplicada, Fac. de Ciencias, Univ. de Vigo, E36310, Spain.
| | - J M Míguez
- Laboratorio de Simulación Molecular y Química Computacional, CIQSO-Centro de Investigación en Química Sostenible and Departamento de Física Aplicada, Facultad de Ciencias Experimentales, Universidad de Huelva, E21071 Huelva, Spain
| | - F J Blas
- Laboratorio de Simulación Molecular y Química Computacional, CIQSO-Centro de Investigación en Química Sostenible and Departamento de Física Aplicada, Facultad de Ciencias Experimentales, Universidad de Huelva, E21071 Huelva, Spain
| | - J-P Torré
- UMR 5150 - Laboratoire des Fluides Complexes et leurs Réservoirs, Université de Pau et des Pays de l'Adour, B. P. 1155, Pau, Cedex 64013, France
| | - M M Piñeiro
- Dpto. de Física Aplicada, Fac. de Ciencias, Univ. de Vigo, E36310, Spain.
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Farfán-García ED, Pérez-Rodríguez M, Espinosa-García C, Castillo-Mendieta NT, Maldonado-Castro M, Querejeta E, Trujillo-Ferrara JG, Soriano-Ursúa MA. Disruption of motor behavior and injury to the CNS induced by 3-thienylboronic acid in mice. Toxicol Appl Pharmacol 2016; 307:130-137. [PMID: 27495897 DOI: 10.1016/j.taap.2016.08.002] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/27/2016] [Revised: 07/30/2016] [Accepted: 08/01/2016] [Indexed: 02/07/2023]
Abstract
The scarcity of studies on boron containing compounds (BCC) in the medicinal field is gradually being remedied. Efforts have been made to explore the effects of BCCs due to the properties that boron confers to molecules. Research has shown that the safety of some BCCs is similar to that found for boron-free compounds (judging from the acute toxicological evaluation). However, it has been observed that the administration of 3-thienylboronic acid (3TB) induced motor disruption in CD1 mice. In the current contribution we studied in deeper form the disruption of motor performance produced by the intraperitoneal administration of 3TB in mice from two strains (CD1 and C57BL6). Disruption of motor activity was dependent not only on the dose of 3TB administered, but also on the DMSO concentration in the vehicle. The ability of 3TB to enter the Central Nervous System (CNS) was evidenced by Raman spectroscopy as well as morphological effects on the CNS, such as loss of neurons yielding biased injury to the substantia nigra and striatum at doses ≥200mg/kg, and involving granular cell damage at doses of 400mg/kg but less injury in the motor cortex. Our work acquaints about the use of this compound in drug design, but the interesting profile as neurotoxic agent invite us to study it regarding the damage on the motor system.
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Affiliation(s)
- E D Farfán-García
- Academias de Fisiología Humana, Bioquímica y Sección de Estudios de Posgrado e Investigación, Escuela Superior de Medicina del Instituto Politécnico Nacional, Plan de San Luis y Díaz Mirón s/n, 11340 Ciudad de México, Mexico
| | - M Pérez-Rodríguez
- Academias de Fisiología Humana, Bioquímica y Sección de Estudios de Posgrado e Investigación, Escuela Superior de Medicina del Instituto Politécnico Nacional, Plan de San Luis y Díaz Mirón s/n, 11340 Ciudad de México, Mexico
| | - C Espinosa-García
- Departamento de Biología de la Reproducción, Universidad Autónoma Metropolitana (UAM), 09310 Ciudad de México, Mexico
| | - N T Castillo-Mendieta
- Academias de Fisiología Humana, Bioquímica y Sección de Estudios de Posgrado e Investigación, Escuela Superior de Medicina del Instituto Politécnico Nacional, Plan de San Luis y Díaz Mirón s/n, 11340 Ciudad de México, Mexico
| | - M Maldonado-Castro
- Academias de Fisiología Humana, Bioquímica y Sección de Estudios de Posgrado e Investigación, Escuela Superior de Medicina del Instituto Politécnico Nacional, Plan de San Luis y Díaz Mirón s/n, 11340 Ciudad de México, Mexico
| | - E Querejeta
- Academias de Fisiología Humana, Bioquímica y Sección de Estudios de Posgrado e Investigación, Escuela Superior de Medicina del Instituto Politécnico Nacional, Plan de San Luis y Díaz Mirón s/n, 11340 Ciudad de México, Mexico
| | - J G Trujillo-Ferrara
- Academias de Fisiología Humana, Bioquímica y Sección de Estudios de Posgrado e Investigación, Escuela Superior de Medicina del Instituto Politécnico Nacional, Plan de San Luis y Díaz Mirón s/n, 11340 Ciudad de México, Mexico
| | - M A Soriano-Ursúa
- Academias de Fisiología Humana, Bioquímica y Sección de Estudios de Posgrado e Investigación, Escuela Superior de Medicina del Instituto Politécnico Nacional, Plan de San Luis y Díaz Mirón s/n, 11340 Ciudad de México, Mexico.
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20
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Pérez-Rodríguez M, Serrano N, Arquero O, Orgaz F, Moral J, López-Escudero FJ. The Effect of Short Irrigation Frequencies on the Development of Verticillium Wilt in the Susceptible Olive Cultivar 'Picual' under Field Conditions. Plant Dis 2016; 100:1880-1888. [PMID: 30682984 DOI: 10.1094/pdis-09-15-1018-re] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/09/2023]
Abstract
The effect of irrigation frequency (daily [T1], biweekly [T2], and dryland [T3]) on Verticillium wilt of olive was studied in two fields that were naturally infested with Verticillium dahliae in southern Spain and planted to 'Picual' olive. Disease onset (average 61 weeks after planting) and disease incidence (average 75.6%) did not differ among irrigation treatments in both fields. Irrigation consistently increased disease development regarding dryland treatment, but this effect varied over time. In experiment I, T1, the relative area under the disease progress curve was greater on all recording dates (ranging from 15.8 to 33.7) in comparison with T3 (average 6.6). Data for experiment II were similar to this on the most favorable dates for disease (March to April). The T2 treatment value varied over time depending on the season and experimental field, being difficult to differentiate from the values of T1 and T3. Significant correlation between disease incidence and severity increments during spring and fall with the soil water content of the same or previous favorable seasons was observed. Through these correlations, we detected soil water contents of 24.3% (experiment I) and 23.6% (experiment II), where the increments of disease parameters remained at zero. Therefore, scheduling irrigation treatments based on rainfall may be a feasible method for maintaining the soil moisture below levels that favor for disease development.
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Affiliation(s)
- M Pérez-Rodríguez
- Departamento de Agronomía, Universidad de Córdoba, Campus Universitario de Rabanales, Edificio Celestino Mutis (C4), 14071, Córdoba, Spain
| | - N Serrano
- IFAPA, Centro 'Alameda del Obispo', 14080 Córdoba, Spain
| | - O Arquero
- IFAPA, Centro 'Alameda del Obispo', 14080 Córdoba, Spain
| | - F Orgaz
- Instituto de Agricultura Sostenible, Consejo Superior de Investigaciones Científicas (CSIC), Apartado 4084, 14080, Córdoba, Spain
| | - J Moral
- Departamento de Agronomía, Universidad de Córdoba, Campus Universitario de Rabanales
| | - F J López-Escudero
- Departamento de Agronomía, Universidad de Córdoba, Campus Universitario de Rabanales
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Abstract
In this work, we use dual cage explicit atomic systems to demonstrate theoretically that direct transitions are feasible through hexagonal and pentagonal faces in type I hydrate without compromising the overall structure integrity.
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Affiliation(s)
- Á. Vidal-Vidal
- Departamento de Física Aplicada
- Universidade de Vigo
- Spain
| | | | - M. M. Piñeiro
- Departamento de Física Aplicada
- Universidade de Vigo
- Spain
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Rodríguez-Carmona Y, Pérez-Rodríguez M, Gámez-Valdez E, López-Alavez FJ, Hernández-Armenta CI, Vega-Monter N, Leyva-García G, Monge-Cázares T, Barrera Valencia D, Balderas Monroy M, Pfeffer F, Meléndez G, Pérez Lizaur AB, Pardío J, Tejero ME. Association between Apolipoprotein E Variants and Obesity-Related Traits in Mexican School Children. J Nutrigenet Nutrigenomics 2015; 7:243-51. [PMID: 25968937 DOI: 10.1159/000381345] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/28/2014] [Accepted: 03/03/2015] [Indexed: 11/19/2022]
Abstract
BACKGROUND/AIM Genetic variation in apolipoprotein E (ApoE) has a key role in lipid metabolism. However, its contribution to the amount and distribution of body fat is under investigation. The aim of this study was to analyze the association between genetic variation in ApoE and obesity-related traits in Mexican school children. MATERIAL AND METHODS Anthropometric, body composition and physical activity measures were conducted using standard methods in 300 children (177 girls/123 boys) who fulfilled the inclusion criteria. DNA was isolated from saliva. ApoE genotypes were analyzed by allelic discrimination. The association between variation in ApoE and anthropometric and body composition measures was investigated using the General Linear Model. RESULTS The mean±SD values for age, body mass index (BMI) and waist circumference (WC) were 9.05±0.80 years, 19.01±3.83 and 67.98±10.97 cm, respectively. Approximately 46% of the participants were overweight or obese. A significant association between ApoE isoforms and WC was found after controlling for age, sex and the percentage of physical activity (p=0.025). Significant main effects were found for vigorous physical activity and light physical activity influencing the adiposity-related BMI (p<0.001) and WC (p=0.044), respectively. CONCLUSIONS Variation in ApoE and physical activity intensity were associated with adiposity-related phenotypes in Mexican school children.
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Pérez-Rodríguez M, Alcántara E, Amaro M, Serrano N, Lorite IJ, Arquero O, Orgaz F, López-Escudero FJ. The Influence of Irrigation Frequency on the Onset and Development of Verticillium Wilt of Olive. Plant Dis 2015; 99:488-495. [PMID: 30699544 DOI: 10.1094/pdis-06-14-0599-re] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/11/2023]
Abstract
The influence of irrigation frequency on the onset and development of Verticillium wilt of olive (VWO) was studied. A split-plot design in microplots with naturally infested soil was established for studying four irrigation frequencies for three olive cultivars with differing levels of disease resistance. Final disease incidence (DI) and mortality in 'Picual' plants subjected to daily irrigation treatment (T1) reached values of 100 and 63%, respectively. For Picual-T1 samples, the area under the disease progress curve values were significantly different between 15 December 2012 and 15 July 2013 (14.8 to 42.8%) compared with the average results of the other treatments, which were weekly (T2), biweekly (T3), and deficit (T4) (0.4 to 11.5%). No significant differences between the irrigation treatments were observed in 'Arbequina', although the DI progressed consistently (60% in all treatments). In 'Frantoio', little disease developed. We conclude that a daily irrigation treatment encourages VWO development in susceptible Picual. Therefore, in susceptible cultivars growing in infested soils under daily irrigation regimes, the extension of irrigation frequency may reduce disease incidence. In the context of an integrated control, the use of resistant cultivars seems to be more relevant than the detrimental effects observed in frequent irrigation schedules.
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Affiliation(s)
- M Pérez-Rodríguez
- Departamento de Agronomía, Universidad de Córdoba, Campus Universitario de Rabanales, Edificio Celestino Mutis (C4), 14071, Córdoba, Spain
| | - E Alcántara
- Departamento de Agronomía, Universidad de Córdoba, Campus Universitario de Rabanales, Edificio Celestino Mutis (C4), 14071, Córdoba, Spain
| | - M Amaro
- Departamento de Agronomía, Universidad de Córdoba, Campus Universitario de Rabanales, Edificio Celestino Mutis (C4), 14071, Córdoba, Spain
| | - N Serrano
- IFAPA, Centro 'Alameda del Obispo', 14080 Córdoba, Spain
| | - I J Lorite
- IFAPA, Centro 'Alameda del Obispo', 14080 Córdoba, Spain
| | - O Arquero
- IFAPA, Centro 'Alameda del Obispo', 14080 Córdoba, Spain
| | - F Orgaz
- Instituto de Agricultura Sostenible, Consejo Superior de Investigaciones Científicas (CSIC), Apartado 4084, 14080, Córdoba, Spain
| | - F J López-Escudero
- Departamento de Agronomía, Universidad de Córdoba, Campus Universitario de Rabanales
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Pérez-Rodríguez M, Palacios-Cruz L, Rivas-Ruiz R, Talavera JO. [Clinical research XXIV. From clinical judgment to ethics in research on humans]. Rev Med Inst Mex Seguro Soc 2014; 52:666-672. [PMID: 25354061 PMCID: PMC7380687] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
Bioethics in research is an essential part of the structured review process of an article and it is based on three fundamental principles: respect for persons, beneficence and justice. In addition to not providing valid knowledge, a research with inadequate design, execution and statistical analysis is not ethical either, since these methodological deficiencies will produce information that will not be useful and, therefore, the risks that the participants were exposed to will have been in vain. Beyond scientific validity, there are other aspects that outline if an investigation is ethical, such as the clinical and social value of a study, a fair selection of participants, favorable risk-benefit balance, an independent review, the informed consent and respect for participants and potential participants. Throughout the article here presented, the documents that profile the behavior of investigators to protect the participants, such as the Declaration of Helsinki, the national regulations that rule us and the differences between research without risk, with minimal risk and with greater than minimal risk are discussed. That like in daily life, behavior in research involving human participants must be self-regulated, ie, people with knowledge of the existence of the law discover that the man is outside the realm of nature where work is done under the necessity of natural causality, and falls within the scope of the will; only if the man is free to decide their actions may be a law regulating their action.
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Affiliation(s)
- Marcela Pérez-Rodríguez
- Centro de Adiestramiento en Investigación Clínica, Coordinación de Investigación en Salud, Centro Médico Nacional Siglo XXI, Instituto Mexicano del Seguro Social, Distrito Federal, México.
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Rivas-Ruiz R, Castelán-Martínez OD, Pérez-Rodríguez M, Palacios-Cruz L, Noyola-Castillo ME, Talavera JO. [Clinical research XXIII. From clinical judgment to meta-analyses]. Rev Med Inst Mex Seguro Soc 2014; 52:558-565. [PMID: 25301131 PMCID: PMC7274139] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
Systematic reviews (SR) are studies made in order to ask clinical questions based on original articles. Meta-analysis (MTA) is the mathematical analysis of SR. These analyses are divided in two groups, those which evaluate the measured results of quantitative variables (for example, the body mass index -BMI-) and those which evaluate qualitative variables (for example, if a patient is alive or dead, or if he is healing or not). Quantitative variables generally use the mean difference analysis and qualitative variables can be performed using several calculations: odds ratio (OR), relative risk (RR), absolute risk reduction (ARR) and hazard ratio (HR). These analyses are represented through forest plots which allow the evaluation of each individual study, as well as the heterogeneity between studies and the overall effect of the intervention. These analyses are mainly based on Student's t test and chi-squared. To take appropriate decisions based on the MTA, it is important to understand the characteristics of statistical methods in order to avoid misinterpretations.
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Affiliation(s)
- Rodolfo Rivas-Ruiz
- Centro de Adiestramiento en Investigación Clínica (CAIC), Coordinación de Investigación en Salud, Centro Médico Nacional Siglo XXI, Instituto Mexicano del Seguro Social, Distrito Federal, México.
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Pérez-Rodríguez M, Rivas-Ruiz R, Palacios-Cruz L, Talavera JO. [Clinical research XXII. From clinical judgment to Cox proportional hazards model]. Rev Med Inst Mex Seguro Soc 2014; 52:430-435. [PMID: 25078746] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
Abstract
Survival analyses are commonly used to determine the time of an event (for example, death). However, they can be used also for other clinical outcomes on the condition that these are dichotomous, for example healing time. These analyses only consider the relationship of one variable. However, Cox proportional hazards model is a multivariate analysis of the survival analysis, in which other potentially confounding covariates of the effect of the main maneuver studied, such as age, gender or disease stage, are taken into account. This analysis can include both quantitative and qualitative variables in the model. The measure of association used is called hazard ratio (HR) or relative risk ratio, which is not the same as the relative risk or odds ratio (OR). The difference is that the HR refers to the possibility that one of the groups develops the event before it is compared with the other group. The proportional hazards multivariate model of Cox is the most widely used in medicine when the phenomenon is studied in two dimensions: time and event.
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Affiliation(s)
- Marcela Pérez-Rodríguez
- Centro de Adiestramiento en Investigación Clínica (CAIC), Coordinación de Investigación en Salud, Centro Médico Nacional Siglo XXI, Instituto Mexicano del Seguro Social, Distrito Federal, México.
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Vázquez-Triñanes C, Rivera A, Freire M, Alonso M, Villaverde I, Pérez-Rodríguez M, del Pozo M, Sopeña B. THU0068 Clinical Risk Factors Associated with the Development of Systemic Disease in Patients with Isolated HLA-B27 Uveitis. Ann Rheum Dis 2014. [DOI: 10.1136/annrheumdis-2014-eular.5872] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
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Rivas-Ruiz R, Pérez-Rodríguez M, Palacios L, Talavera JO. [Clinical research XXI. From the clinical judgment to survival analysis]. Rev Med Inst Mex Seguro Soc 2014; 52:308-315. [PMID: 24878091] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
Abstract
Decision making in health care implies knowledge of the clinical course of the disease. Knowing the course allows us to estimate the likelihood of occurrence of a phenomenon at a given time or its duration. Within the statistical models that allow us to have a summary measure to estimate the time of occurrence of a phenomenon in a given population are the linear regression (the outcome variable is continuous and normally distributed -time to the occurrence of the event-), logistic regression (outcome variable is dichotomous, and it is evaluated at one single interval), and survival curves (outcome event is dichotomous, and it can be evaluated at multiple intervals). The first reference we have of this type of analysis is the work of the astronomer Edmond Halley, an English physicist and mathematician, famous for the calculation of the appearance of the comet orbit, recognized as the first periodic comet (1P/Halley's Comet). Halley also contributed in the area of health to estimate the mortality rate for a Polish population. The survival curve allows us to estimate the probability of an event occurring at different intervals. Also, it leds us to estimate the median survival time of any phenomenon of interest (although the used term is survival, the outcome does not need to be death, it may be the occurrence of any other event).
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Affiliation(s)
- Rodolfo Rivas-Ruiz
- Centro de Adiestramiento en Investigación Clínica (CAIC), Coordinación de Investigación en Salud, Instituto Mexicano del Seguro Social, Distrito Federal, México.
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Berea-Baltierra R, Rivas-Ruiz R, Pérez-Rodríguez M, Palacios-Cruz L, Moreno J, Talavera JO. [Clinical research XX. From clinical judgment to multiple logistic regression model]. Rev Med Inst Mex Seguro Soc 2014; 52:192-197. [PMID: 24758859] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
Abstract
The complexity of the causality phenomenon in clinical practice implies that the result of a maneuver is not solely caused by the maneuver, but by the interaction among the maneuver and other baseline factors or variables occurring during the maneuver. This requires methodological designs that allow the evaluation of these variables. When the outcome is a binary variable, we use the multiple logistic regression model (MLRM). This multivariate model is useful when we want to predict or explain, adjusting due to the effect of several risk factors, the effect of a maneuver or exposition over the outcome. In order to perform an MLRM, the outcome or dependent variable must be a binary variable and both categories must mutually exclude each other (i.e. live/death, healthy/ill); on the other hand, independent variables or risk factors may be either qualitative or quantitative. The effect measure obtained from this model is the odds ratio (OR) with 95 % confidence intervals (CI), from which we can estimate the proportion of the outcome's variability explained through the risk factors. For these reasons, the MLRM is used in clinical research, since one of the main objectives in clinical practice comprises the ability to predict or explain an event where different risk or prognostic factors are taken into account.
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Affiliation(s)
- Ricardo Berea-Baltierra
- Departamento de Medicina Interna, Hospital de Oncología, Centro Médico Nacional Siglo XXI, Instituto Mexicano del Seguro Social, Distrito Federal, México.
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Pérez-Rodríguez M, Palacios-Cruz L, Moreno J, Rivas-Ruiz R, Talavera JO. [Clinical research XIX. From clinical judgment to analysis of covariance]. Rev Med Inst Mex Seguro Soc 2014; 52:70-75. [PMID: 24625487] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
Abstract
The analysis of covariance (ANCOVA) is based on the general linear models. This technique involves a regression model, often multiple, in which the outcome is presented as a continuous variable, the independent variables are qualitative or are introduced into the model as dummy or dichotomous variables, and factors for which adjustment is required (covariates) can be in any measurement level (i.e. nominal, ordinal or continuous). The maneuvers can be entered into the model as 1) fixed effects, or 2) random effects. The difference between fixed effects and random effects depends on the type of information we want from the analysis of the effects. ANCOVA effect separates the independent variables from the effect of co-variables, i.e., corrects the dependent variable eliminating the influence of covariates, given that these variables change in conjunction with maneuvers or treatments, affecting the outcome variable. ANCOVA should be done only if it meets three assumptions: 1) the relationship between the covariate and the outcome is linear, 2) there is homogeneity of slopes, and 3) the covariate and the independent variable are independent from each other.
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Affiliation(s)
- Marcela Pérez-Rodríguez
- Centro de Adiestramiento en Investigación Clínica (CAIC), Coordinación de Investigación en Salud, Centro Médico Nacional Siglo XXI, Instituto Mexicano del Seguro Social. Distrito Federal, México.
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Rivas-Ruiz R, Pérez-Rodríguez M, Talavera JO. [Clinical research XV. From the clinical judgment to the statistical model. Difference between means. Student's t test]. Rev Med Inst Mex Seguro Soc 2013; 51:300-303. [PMID: 23883459] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 06/02/2023]
Abstract
Among the test to show differences between means, the Student t test is the most characteristic. Its basic algebraic structure shows the difference between two means weighted by their dispersion. In this way, you can estimate the p value and the 95 % confidence interval of the mean difference. An essential feature is that the variable from which the mean is going to be calculated must have a normal distribution. The Student t test is used to compare two unrelated means (compared between two maneuvers), this is known as t test for independent samples. It is also used to compare two related means (a comparison before and after a maneuver in just one group), what is called paired t test. When the comparison is between more than two means (three or more dependent means, or three or more independent means) an ANOVA test (or an analysis of variance) it is used to perform the analysis.
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Affiliation(s)
- Rodolfo Rivas-Ruiz
- Centro de Adiestramiento en Investigación Clínica, Coordinación de Investigación en Salud, Centro Médico Nacional Siglo XXI, Instituto Mexicano del Seguro Social, Distrito Federal, México, Mexico.
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Abstract
We have identified a novel HLA-DQA1 allele in the homozygous cell line KGV (I HW9309) derived from a Caucasoid individual from the Indian subcontinent. This novel allele, DQA1*01042, differs from the DQA1*01041 allele by a single synonymous substituition within exon 3, position 438A-->C.1
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Affiliation(s)
- M Pérez-Rodríguez
- Anthony Nolan Research Institute, The Royal Free Hospital, London, UK
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Abstract
The MHC Class I related (MIC) gene family has been shown to be very polymorphic with 46 different MICA alleles being officially named by the WHO Nomenclature Committee for factors of the HLA system to date. We have identified a novel MICA allele, MICA*047, in a Coya American Indian individual from the Jujuy province of north-western Argentina. The novel MICA*047 allele differs from the MICA*030 allele by a single non-synonymous substitution in exon 2, condon 26 GTA-->GGA, Valine to Glycine1.
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Affiliation(s)
- M Pérez-Rodríguez
- Anthony Nolan Research Institute, The Royal Free Hospital, London, UK
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Pérez-Rodríguez M, Argüello JR, Fischer G, Corell A, Cox ST, Robinson J, Hossain E, McWhinnie A, Travers PJ, Marsh SGE, Madrigal JA. Further polymorphism of the MICA gene. Eur J Immunogenet 2002; 29:35-46. [PMID: 11841487 DOI: 10.1046/j.0960-7420.2001.00275.x] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/12/2023]
Abstract
The MHC class I chain-related (MIC) gene family constitutes an interesting genetic group that is related to major histocompatibility complex (MHC) class I genes and is located within the MHC. The MIC gene products, MICA and MICB, have similar structures to HLA class I molecules. So far over 50 MICA alleles have been reported, which suggests that this genetic system is highly polymorphic. In order to investigate further the extent of MICA polymorphism we have studied exons 2-5 of the MICA gene in over 200 homozygous and heterozygous cell lines. Altogether we have identified 11 new MICA alleles and report 13 new nucleotide variations, one in exon 2, four in exon 3, four in exon 4, two in intron 1, one in intron 4 and one (a deletion) in exon 4. Eight of the 10 exonic variations are non-synonymous. The deletion in exon 4 leads to a frame-shift mutation and the introduction of a repeat of 12 leucine residues encoded by the microsatellite in exon 5. This study provides further evidence that the MICA gene is highly polymorphic. In contrast to MHC class I molecules, the polymorphic sites in MICA are predominantly within the alpha2 and alpha3 domains. The distribution of synonymous and non-synonymous substitutions suggests that there is selection for the polymorphic positions, which therefore define potential functional sites in the protein. We were also able to determine the association between MICA and HLA-B alleles in a number of homozygous cell lines bearing extended haplotypes.
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Affiliation(s)
- M Pérez-Rodríguez
- Anthony Nolan Research Institute, The Royal Free Hospital, Pond Street, Hampstead, London NW3 2QG, UK
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Affiliation(s)
- J Robinson
- Anthony Nolan Research Institute, Royal Free Hospital, Pond Street, London NW3 2QG, UK
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Pérez-Rodríguez M, Varela LM, Taboada P, Attwood D, Mosquera V. The temperature dependence of the micellisation of chlorpromazine hydrochloride in aqueous solution. Colloid Polym Sci 2000. [DOI: 10.1007/s003960000331] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
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Fischer G, Argüello JR, Pérez-Rodríguez M, McWhinnie A, Marsh SG, Travers PJ, Madrigal JA. Sequence-specific oligonucleotide probing for MICB alleles reveals associations with MICA and HLA-B. Immunogenetics 2000; 51:591-9. [PMID: 10912510 DOI: 10.1007/s002510000179] [Citation(s) in RCA: 20] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Affiliation(s)
- G Fischer
- The Anthony Nolan Research Institute, The Royal Free Hospital, London, UK
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Pérez-Rodríguez M, Corell A, Argüello JR, Cox ST, McWhinnie A, Marsh SG, Madrigal JA. A new MICA allele with ten alanine residues in the exon 5 microsatellite. Tissue Antigens 2000; 55:162-5. [PMID: 10746789 DOI: 10.1034/j.1399-0039.2000.550209.x] [Citation(s) in RCA: 42] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
The MICA and MICB genes code for protein products that have structural similarities to major histocompatibility complex (MHC) class I genes. These genes are upregulated by heat stress. They have been shown to interact with a common receptor (NKG2D/DAP10) on gammadelta T cells, CD8+ T cells and natural killer (NK) cells. The MICA gene has an expressed microsatellite, GCT, within the exon 5 which encodes for alanine. So far, four different repetitions of this short tandem have been reported. Also one non-synonymous, one synonymous substitution and a 1-bp insertion within this region have also been described. An association of Behcet's disease with the microsatellite A9 has been reported. Here we report a novel allele with 10 GCT repetitions (A10) which was detected by reference strand mediated conformation analysis and confirmed by DNA sequencing.
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Affiliation(s)
- M Pérez-Rodríguez
- Anthony Nolan Research Institute, The Royal Free Hospital, London, United Kingdom
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Abstract
The two members of the MHC class I chain-related (MIC) gene family, MICA and MICB, have been shown by several investigators to be polymorphic. Most of the research effort so far has focussed on MICA, so less is known about the extent of polymorphism in the MICB gene. Here we report three novel MICB alleles, which had been detected in the course of an SSOP typing study on a large cohort of cell lines. Two of these alleles are formed by a non-synonymous nucleotide variation. Our results confirm previous findings that most of the polymorphisms in the MICB gene, as in MICA, are coding and suggest that the extent of polymorphism in the two genes might be comparable.
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Affiliation(s)
- G Fischer
- The Anthony Nolan Research Institute, The Royal Free Hospital, London, United Kingdom
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Fischer G, Argüello JR, Pérez-Rodríguez M, Cox ST, McWhinnie A, Marsh SG, Madrigal JA. Novel intronic variants of MICB (MHC class I chain-related gene B). Eur J Immunogenet 1999; 26:399-404. [PMID: 10583461 DOI: 10.1046/j.1365-2370.1999.00182.x] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
We report an eight-nucleotide duplication in intron 4 of the MICB allele 01021, which was found in samples from different ethnic backgrounds and in association with several HLA-B alleles. We suggest that this new MICB allele is evolutionarily older than HLA-B alleles.
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Affiliation(s)
- G Fischer
- Anthony Nolan Research Institute, The Royal Free Hospital, Pond Street, Hampstead, London NW3 2QG, UK
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Mendoza-Rincon J, Argüello JR, Pérez-Rodríguez M, McWhinnie A, Marsh SG, Fischer G, Madrigal JA. Characterization of the MICA polymorphism by sequence-specific oligonucleotide probing. Immunogenetics 1999; 49:471-8. [PMID: 10380690 DOI: 10.1007/s002510050523] [Citation(s) in RCA: 22] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/28/2022]
Abstract
A large number of diseases occur in association with specific HLA-B or -C alleles. Recently a new gene, termed major histocompatibility complex class I chain-related gene A (MICA), has been identified in close proximity to HLA-B. The function of this gene is still unknown, but, it is structurally related to HLA class I genes, is polymorphic, and is potentially associated with several diseases. Some DNA-based techniques have previously been described to type for MICA including sequencing and single-strand conformational polymorphism. In this paper we describe the application of sequence-specific oligonucleotide probe based typing for the analysis of the MICA gene. We used a set of 30 oligonucleotide probes to screen for the polymorphisms in exons 2, 3, and 4, which account for the 16 known alleles. We report here the typing results of MICA for 103 B-cell lines that have been well characterized for HLA and describe the linkage disequilibrium between MICA and HLA-B. Unequivocal MICA typing was achieved for 85 of the 103 cells tested, 6 cells gave ambiguous MICA types, and a further 12 cells showed patterns consistent with them expressing at least one new MICA allele.
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Affiliation(s)
- J Mendoza-Rincon
- Anthony Nolan Research Institute, Royal Free Hospital, London, UK
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Pérez-Rodríguez M, Arellano J, López-Osuna M, Velázquez JR, Granados J, Justiniani N, Santos JI, Madrazo A, Muñoz L, Kretschmer R. Increased frequency of HLA-DR3 and complotype SC01 in Mexican Mestizo children with amebic abscess of the liver and summary of our overall HLA-SC01 experience in invasive amebiasis. Arch Med Res 1997; 28 Spec No:245-7. [PMID: 9033088] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Affiliation(s)
- M Pérez-Rodríguez
- División de Inmunologia, Coordinación de Investigación Médica, Centro Médico Nacional Siglo XXI, Instituto Mexicano del Seguro Social, México, D.F., Mexico
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