Standardization of a Cytometric Bead Assay Based on Egg-Yolk Antibodies.

Immunoassays are important tests for the detection of numerous molecular targets. Among the methods currently available, the cytometric bead assay has gained prominence in recent decades. Each microsphere that is read by the equipment represents an analysis event of the interaction capacity between the molecules under test. Thousands of these events are read in a single assay, thus ensuring high assay accuracy and reproducibility. This methodology can also be used in the validation of new inputs, such as IgY antibodies, for the diagnosis of diseases. These antibodies are obtained through immunizing chickens with the antigen of interest and then extracting the immunoglobulin from the yolk of the animals' eggs; therefore, this is a painless and highly productive method for obtaining the antibodies. In addition to a methodology for the high-precision validation of the antibody recognition capacity of this assay, this paper also presents a method for extracting these antibodies, determining the best coupling conditions for the antibodies and latex beads, and determining the sensitivity of the test.

Application of egg yolk IgY on carboxylated polypyrrole films for impedimetric detection of PfHRP2 antigen.

This paper described an impedimetric immunosensor for detecting Plasmodium falciparum histidine-rich protein 2 (PfHRP2). Antibodies from egg yolk (Ab-PfHRP2, IgY type) were linked covalently to the screen-printed gold electrodes (SPGE) surface modified with a thin film of Poly-pyrrole-pyrrole 3 carboxylic acid (P(Py-Py3COOH) to develop the sensing platform. The fabrication steps were followed by microscopic (scanning electron microscopy), spectroscopic (RAMAN spectroscopy and Energy-dispersive X-ray spectroscopy), and electrochemical (electrochemical impedance spectroscopy (EIS) and cyclic voltammetry) techniques. The determination of Ag-PfHRP2 was performed by EIS, and the BSA(bovine serum albumin)/Ab-PfHRP2(IgY)/P(Py-Py3COOH)/SPGE immunosensor recorded a linear response at 100-1000 ng mL-1 concentration range, with a limit of detection (LOD) of 27.47 ng mL-1. Its performance was confirmed by Enzyme-Linked Immuno-Sorbent Assay. The fabricated device uses a simple strategy of IgY immobilization, showing high sensitivity and good selectivity, and can be considered an alternative for carrying out malaria tests.

One-step enzyme-free dual electrochemical immunosensor for histidine-rich protein 2 determination.

In the present work, we describe a novel one-step enzyme-free dual electrochemical immunosensor for the determination of histidine-rich protein 2 (Ag-PfHRP2), a specific malaria biomarker. A gold electrode (GE) was functionalized with the PfHRP2 antibody (Ab-PfHRP2) using dihexadecyl phosphate (DHP) polymer as an immobilization platform. The Ab-PfHRP2/DHP/GE sensor was characterized by cyclic voltammetry, electrochemical impedance spectroscopy, Fourier-transform infrared spectroscopy, scanning electron microscopy, and atomic force microscopy. The developed immunosensor was employed for indirect Ag-PfHRP2 determination by differential pulse voltammetry (DPV) and electrochemical impedance spectroscopy (EIS). The linear range was 10-400 ng mL-1 and 10-500 ng mL-1 for EIS and DPV, while the limit of detection was 3.3 ng mL-1 and 2.8 ng mL-1, respectively. The electrochemical immunosensor was successfully applied for Ag-PfHRP2 determination in human serum samples. Its performance was compared with an ELISA test, and good correspondence was achieved. The coefficients of intra- and inter-assay variations were less than 5%. The electrochemical immunosensor is a useful and straightforward tool for in situ malaria biomarker determination.

[Association between diabetes mellitus and cognitive decline in older adults. A population based study]. / Asociación de diabetes mellitus con deterioro cognitivo en adultos mayores. Estudio basado en población.

BACKGROUND: The association between diabetes and cognitive decline is already known; however, there is not much literature that document if this association is different according to gender. The aim of this study was to determine this relationship and to establish if there is a difference according to gender in older adults of Mérida, Yucatán, México. METHODS: 1293 older than sixty years old individuals without severe depression, history of psychiatric disease or stroke were included in the study. A structured survey was applied to them, including mini-mental state examination, anthropometry, capillary glucose and lipid measurements. These parameters were compared between diabetic and non-diabetic patients. The association between diabetes and cognitive decline was determined first to general population and then in each sex with logistic regression. RESULTS: Prevalence of diabetes was 27.38 %. Diabetic patients were younger (p = 0.049), with less years of formal education (p = 0.014) and with a larger waist circumference (p = 0.004) than non-diabetics. Diabetes was associated to a greater frequency of cognitive decline only in women (ß = 2.897, IC 95 % 1.428-5.877, p = 0.003). CONCLUSIONS: There is an association between diabetes and cognitive decline in women older than 60 years of age. However, there is a need of longitudinal studies that confirm these findings.

Introducción: la asociación entre diabetes y deterioro cognitivo es conocida; sin embargo, existen pocos datos respecto a si esta asociación es diferente a partir del sexo. Este estudio pretende determinar esta asociación y establecer si existe diferencia de acuerdo al sexo, en adultos mayores de Mérida, Yucatán, México. Métodos: participaron 1293 personas mayores de 60 años sin depresión grave, historia de enfermedad psiquiátrica, o evento vascular cerebral, a quienes se les aplicó una encuesta estructurada que incluyó el mini examen del estado mental, antropometría y medición capilar de glucosa y lípidos. Se compararon estos parámetros entre pacientes diabéticos y no diabéticos. Se determinó la asociación de diabetes con deterioro cognitivo mediante regresión logística para la población en general y para cada uno de los sexos. Resultados: la prevalencia de diabetes fue del 27.38 %. Los pacientes diabéticos fueron más jóvenes (p = 0.049), con menor escolaridad (p = 0.014) y con mayor circunferencia abdominal (p = 0.004) que los no diabéticos. La diabetes estuvo asociada a una mayor frecuencia de deterioro cognitivo únicamente en las mujeres (ß = 2.897, IC 95 % 1.428-5.877, p = 0.003). Conclusión: existe asociación entre diabetes y deterioro cognitivo en mujeres mayores de 60 años. Hacen falta estudios longitudinales que confirmen estos hallazgos.

Factores asociados a la consulta odontológica en niños/as y jóvenes de Talca (Chile) e inmigrantes chilenos de Montreal (Canadá) / Factors associated with dental consultation in children in Talca (Chile) and in Chilean immigrants in Montreal (Canada)

Objetivo: Determinar los factores que influyen en la consulta al odontólogo de los/las niños/as de 4 a 7 años y los/las jóvenes de 10-13 años de edad residentes de la ciudad de Talca (Chile) y los/las niños/as y los/las jóvenes inmigrantes chilenos residentes en la ciudad de Montreal (Canadá). Métodos: Estudio transversal no probabilístico, con 147 niños/as en Talca y 94 en Montreal. Entre 2009 y 2011 se midieron variables sociodemográficas, nivel de estudios, percepción de la salud de los/las hijos/as, sexo y edad de los/las niños/as, composición familiar y cercanía al centro de salud. Se hizo análisis exploratorio bivariado con test exacto de Fisher. Para buscar las variables asociadas a la consulta odontológica se utilizó la regresión de Cox robusta con tiempo constante con nivel de significación de 0,05. Resultados: En Talca las variables asociadas a la consulta odontológica de dos o más veces al año fueron el nivel de estudios del/de la tutor/a y su percepción sobre la salud del/de la hijo/a, teniendo los/las niños/as con tutores/as con estudios universitarios 2,20 (intervalo de confianza del 95% [IC95%]: 1,30-3,73) veces más posibilidades de consultar al dentista y los/las tutores/as con percepción positiva consultan 53% menos al dentista (odds ratio: 0,47; IC95%: 0,28-0,77). En Montreal, los/las niños/as con tutores/as con estudios universitarios tenían 2,10 veces más posibilidades (IC95%: 1,17-3,76) de consultar al dentista y 2,11 veces más posibilidades de consultar si tenían entre 10 y 13 años de edad (IC95%: 1,15-3,88). Conclusiones: El nivel de estudios del/de la tutor/a se asoció con las visitas al dentista en ambas muestras, siendo los/las niños/as con tutores/as de mayor nivel de estudios quienes más consultan (AU)

Objective: To identify the factors that influence the use of dental services in 4-7-year-olds and in 10-13-year-olds resident in the cities of Talca (Chile) and Montreal (Canada). Methods: A nonprobabilistic cross-sectional study was carried out in 147 boys and girls in Talca and in 94 boys and girls in Montreal between 2009 and 2011. Sociodemographic variables were recorded in parents and children, including age and sex. Data were also gathered on parental education, family composition, and proximity to health centers within neighborhoods. The data were analyzed with Fisher's exact test and the robust Cox regression model (with constant time) with a significance level of 0,05. Results: In Talca, parental education was significantly associated with dental care visits at least twice a year. The children of parents with university education were 2.20 times more likely to consult a dentist (95% CI: 1.30-3.73). Children whose parents perceived their children's health positively were 53% (OR = 0,47; 95% CI: 0,28-0,77) less likely to consult a dentist. In Montreal, the children of parents with university education were 2.10 times more likely to consult a dentist (95%CI: 1.17-3.76), while older children (10-13 years) were 2.11 (95% CI: 1.15-3.88) times more likely to consult a dentist. Conclusions: In both cities, parental education level was associated with the use of dental services (AU)

[Factors associated with dental consultation in children in Talca (Chile) and in Chilean immigrants in Montreal (Canada)]. / Factores asociados a la consulta odontológica en niños/as y jóvenes de Talca (Chile) e inmigrantes chilenos de Montreal, (Canadá).

OBJECTIVE: To identify the factors that influence the use of dental services in 4-7-year-olds and in 10-13-year-olds resident in the cities of Talca (Chile) and Montreal (Canada). METHODS: A nonprobabilistic cross-sectional study was carried out in 147 boys and girls in Talca and in 94 boys and girls in Montreal between 2009 and 2011. Sociodemographic variables were recorded in parents and children, including age and sex. Data were also gathered on parental education, family composition, and proximity to health centers within neighborhoods. The data were analyzed with Fisher's exact test and the robust Cox regression model (with constant time) with a significance level of 0,05. RESULTS: In Talca, parental education was significantly associated with dental care visits at least twice a year. The children of parents with university education were 2.20 times more likely to consult a dentist (95% CI: 1.30-3.73). Children whose parents perceived their children's health positively were 53% (OR = 0,47; 95% CI: 0,28-0,77) less likely to consult a dentist. In Montreal, the children of parents with university education were 2.10 times more likely to consult a dentist (95%CI: 1.17-3.76), while older children (10-13 years) were 2.11 (95% CI: 1.15-3.88) times more likely to consult a dentist. CONCLUSIONS: In both cities, parental education level was associated with the use of dental services.

Estudio comparativo, cruzado, al azar, para la determinación de la bioequivalencia entre dos formulaciones de oxcarbazepina en tabletas / Bioequivalence comparison of two formulations of oxcarbazepine tablets: a two period, single dose, randomized, cross-over study

Dos formulaciones de oxcarbazepina (Trileptal®, Novartis, y Oxcarbazepina®, Tecnoquímicas S. A.), previamente demostradas como equivalentes farmacéuticos, fueron evaluadas en cuanto a bioequivalencia por medio de un estudio aleatorizado, cruzado, en dos períodos, con dosis oral única de 1.200 mg, en 24 hombres adultos voluntarios sanos entre 18-35 años. Se evaluaron los siguientes parámetros farmacocinéticos: Área bajo la curva (AUC), Concentración máxima (Cmáx) y Tiempo para alcanzar la concentración máxima (Tmáx). Hubo un intervalo de lavado de siete días entre los dos períodos. Las concentraciones plasmáticas se evaluaron por HPLC/UV con el método de la adición estándar. No se encontraron diferencias significativas entre las dos preparaciones. Se concluyó que las dos preparaciones son equivalentes farmacéuticos y bioequivalentes y que, en consecuencia, son intercambiables para propósitos terapéuticos.

Two formulations of oxcarbazepine (Trileptal®, Novartis, y Oxcarbazepina®, Tecnoquímicas S. A.), previously shown to be pharmaceutical equivalents, were evaluated concerning their bioequivalence by means of a randomized, crossover, single oral dose (1.200 mg), two-period study in 24 healthy adult males. The following pharmacokinetic parameters were determined: Area under the curve (AUC), Maximal concentration (Cmax), and Time to reach maximal concentration (Tmax). There was a wash-out interval of seven days between the two periods. Plasmatic concentrations of the drug were measured with HPLC/UV with standard addition. No significant differences were found between the two preparations. It was concluded that they are pharmaceutical equivalents as well as bioequivalent. Consequently, they are interchangeable for therapeutic purposes.

Direct medical costs for partial refractory epilepsy in Mexico.

BACKGROUND: The aim was to determine the direct medical costs in patients with partial refractory epilepsy at the Mexican Institute of Social Security (IMSS) in Mexico. METHODS: We carried out a multicenter, retrospective-cohort partial-economic evaluation study of partial refractory epilepsy (PRE) diagnosed patients and analyzed patient files from four secondary- and tertiary-level hospitals. PRE patients >12 years of age with two or more antiepileptic drugs and follow-up for at least 1 year were included. The perspective was institutional (IMSS). Only direct healthcare costs were considered, and the timeline was 1 year. Cost techniques were microcosting, average per-service cost, and per-day cost, all costs expressed in U.S. dollars (USD, 2004). RESULTS: We reviewed 813 files of PRE patients: 133 had a correct diagnosis, and only 72 met study inclusion criteria. Fifty eight percent were females, 64% were <35 years of age, 47% were students, in 73% maximum academic level achieved was high school, and 53% were single. Fifty one percent of cases experienced simple partial seizures and 94% had more than one monthly seizure. Annual healthcare cost of the 72 patients was 190,486 USD, ambulatory healthcare contributing 76% and hospital healthcare with 24%. CONCLUSIONS: Annual mean healthcare cost per PRE patient was 2,646 USD; time of disease evolution and severity of the patient's illness did not affect costs significantly.

[Prevalence and functional impact of arthropathies in elderly adults]. / Prevalencia e impacto funcional de las artropatías en adultos mayores.

INTRODUCTION: Musculoskeletal disorders are public health issues in the entire world; their impact seems to be higher on elderly people. OBJECTIVE: To establish the prevalence and the functional impact of arthropathies on the elderly people from Mérida, Yucatán, México. MATERIAL AND METHODS: The SABE-PAHO survey was administered to a random sample of people older than 60 Mérida, Yucatán, México. Arthropathy was evaluated by self report; on the other hand, physical function was evaluated using the modified Katz's scale (basic activities of daily living, BADL) and the Lawton's scale (instrumental activities of daily living, IADL). RESULTS: 1747 patients (68.6% females, 31.4% males), aged 71.5 +/- 8.5 years old, were studied; 498 (28.5%; 95% CI = 26.4 to 30.6) had arthropathy. After logistic regression and adjustment for chronic obstructive lung disease, ischemic cardiopathy, and stroke presence or to be older than 80 were performed, arthropathy was found associated to BADL (p=0.03) as well to IADL (p=0.04) impairment. CONCLUSIONS: The prevalence of arthropathy in elderly people from Mérida, México, was 28.5%, it was found to be independently associated to impairment for BADL and IADL.

[Neurosarcoidosis. Report of one case in Mexico]. / Neurosarcoidosis. Informe de un caso un México.

INTRODUCTION: The sarcoidosis is a granulomatous, multisystemic disease, of unknown etiology that mainly affects the lungs, skin and lymphatic ganglia. The definitive diagnosis is made by the presence of granulomas non-caseous in diverse organs. Sarcoidosis is rare in Mexico and reports of its incidence do not exist. In Spain the incidence is low (1.2 to 1.5 cases by 100,000 inhabitants). In the United States incidence is 5.9 to 6.3 cases by 100,000 inhabitants (males and females respectively). Neurosarcoidosis is present in 5 to 26% of all the patients with sarcoidosis. The neurological manifestations are diverse, depending on the location site. CLINICAL CASE: We present the case of a male 33 years old, with recurrent facial paralysis, optic neuritis and affection of the third cranial nerve; the tomography of skull reveled an grow of left cavernous sinus and reinforcing bilateral temporal giral, and the nuclear magnetic resonance showed leptomeningeal reinforcing in the temporal lobe. CONCLUSION: Although the neurosarcoidosis is rare in Mexico, it should be considered in patients with suggestive clinical manifestations and compatible imaging findings. It should be done an intense search of systemic affection with biopsy and verification of non-caseous granulomas.

Aspectos prácticos sobre el tamaño de la muestra en la investigación clínica / Practical aspects about the size of the sample in clinical research

Antecedentes: El conocimiento el tamaño apropiado de una muestra nos permite estar seguros de si los resultados publicados en diversos informes de la literatura médica tuvieron como base, además de un diseño cuidadoso, una conclusión apropiada, en función de la significancia de la diferencia observada. Para caulcular el tamaño de la muestra debemos tener en cuenta los errores tipo I y II, la varianza, la magnitud del efecto, el nivel de significancia y el poder de la prueba. Para decidir qué tipo de fórmula matemática se utlizará, lo primero que debemos observar es si nuestro estudio es de prevalencia de valores promedio o comparativo. En este artículo se explican algunos conceptos básicos de estadística y se dan cuatro ejemplos sencillos de cálculo de tamaño de muestra.

Participación de la familia en el desarrollo de la comprensión de lectura. Estrategias metodológicas / Family participation in reading comprehension development. Methodological strategies

La propuesta metodológica planteada en este artículo está sustentada desde una perspectiva psicolinguística, en la que se acepta que el lector cumple un papel muy activo: recrea sentidos, moviliza sentimientos, forma imágenes mentales y aprende; en fin, trasciende los pensamientos, ideas y sentimientos expresados por el autor a través del texto escrito. Numerosas investigaciones han demostrado que los niños no llegan al sistema escolar en completo desconocimiento del lenguaje escrito; y si son estimulados desde el hogar presenciando y participando en actos de lectura y escritura, desarrollan esquemas cognitivos y lingûísticos que les permiten aprender con facilidad y provecho. Aunque muchos padres de familia están interesados en colaborar desde sus hogares en la formación de lectores y escritores, por lo general, no saben cómo orientar sus buenos deseos. Así que, pensando en ellos, a continuación se expone, de forma abreviada, información teórica sobre el proceso lector y sugerencias sobre actividades para acompañar la lectura de los cuentos y de otros tipos de materiales de lectura, de modo que puedan ejercer acciones pedagógicas que armonicen con los intereses de los niños y les posibilite, además, momentos placenteros. En la última parte, se ofrecen algunas sugerencias para los niños que ya saben leer y escribir.

El estudio de la función renal a traves de la depuración de la creatina / Correlation between renal function and creatine plasma concentration

En este trabajo se correlaciona el nivel plasmático de la creatinina con su depuración. De la curva obtenida se estudian tres segmentos: 1) Cuando la filtración es mayor de 60 ml/min, el nivel plasmático fluctúa entre 0.44 y 1.59 mg/dl. 2)Cuando la filtración fluctúa entre 30 y 60 ml/min, el nivel plasmático llega hasta 2.4 mg/dl y 3) Cuando la filtración es menor de 30 ml/min, los niveles plasmáticos aumentan hasta valores de 28 mg/ml. La concentración urinaria de creatinina puede dividirse en dos grandes grupos dependiendo de la filtración glomerular. La frontera de esta división está dada alrededor de 60 ml/min. Esto sugiere que cuando la filtración glomerular está deprimida existiría una limitación de la secreción tubular de la creatinina o problemas de dilución urinaria. Se demuestra que existe una pobre correlación entre la depuración de la creatinina y su nivel plasmático, lo que hace imperativo el estudio reiterado de la depuración de la creatinina en el control de los pacientes.