Search

El sargazo (Sargassum spp.) es una macroalga parda que durante la última década ha presentado arribos anómalos en playas caribeñas, generando una problemática al turismo local por el aspecto y olor que adquiere cundo se descompone sobre el litoral. Para dar alternativas de manejo algunas investigaciones han propuesto incorporarlo a diferentes procesos industriales que van desde la cosmética, la construcción y la producción de alimentos. Dentro este último, se han reportado tratamientos para su acondicionamiento físico-químico y posterior uso como sustrato agrícola, sin embargo, las investigaciones de su desempeño son escasas. Por ello en el presente trabajo se determinaron las características físicas y químicas de una muestra del alga colectada en Puerto Progreso, Yucatán, México, así como las implicaciones de estas sobre la germinación de dos especies hortícolas. Las determinaciones fueron comparadas con las características y desempeño de turba (Sphagnum spp. Comercialmente llamado Peat moss®). Los resultados mostraron propiedades físicas desfavorables cuando se usa como componente único, así como una alta concentración de plomo (Pb), ion sodio y calcio que limitan su uso en la industria alimenticia, además de que interfieren negativamente con las etapas de germinación. Debido a esto, se recomienda probar mezclas de sargazo con otros materiales que permitan mejorar sus características físicas, así como amortiguar las concentraciones de metales, además de idear mecanismos para reducir su concentración o eliminarlos completamente del sustrato.

Desde el año 2003 en algunos viveros forestales del país se utilizan sustratos con aserrín fresco de pino y oyamel. Debido a la disponibilidad de aserrín de una variedad mayor de especies, este estudio planteó la hipótesis de que los sustratos con aserrín fresco de latifoliadas son aptos para producir planta de Pinus patula con calidad similar a la que se produce en sustratos con aserrín de especies de pino u oyamel. Para probarla, el objetivo fue evaluar el crecimiento de plantas de P. patula en charolas de poliestireno llenas con sustratos con 60% de aserrín fresco de las 11 principales especies forestales maderables (coníferas y latifoliadas) que se aprovechan en las regiones centro y sureste de México. El aserrín utilizado fue de las especies: Abies religiosa, Hevea brasiliensis, Gmelina arborea, Mangifera indica, Pinus ayacahuite, Pinus montezumae, Pinus patula, Pinus teocote, Quercus laurina, Quercus rugosa y Tectona grandis. Las charolas (77 cavidades de 170 cm3) se llenaron con mezcla de sustrato con aserrín (60%), corteza de pino compostada, perlita y vermiculita (20, 10 y 10%). A cada mezcla para rellenar charolas se adicionó fertilizante: Multicote® 18-6-12 y 12-24-12 (N-P2O5-K2O) de 8 meses de liberación (4 g L-1 de cada uno) y Micromax® (1 g L-1). El diseño experimental fue completamente al azar e incluyó 11 tratamientos y cuatro repeticiones. A los siete meses se presentaron diferencias (p≤0.05) por tratamiento en diámetro, altura, pesos secos, índices de robustez y de calidad de Dickson, y en la concentración foliar de N, K, Mg, Fe, Mn, Zn, Cu y B. Con todos los sustratos se obtuvieron índices de calidad de Dickson ≥0.47; diámetros ≥4 mm y alturas de 20 a 30 cm, excepto el de M. indica. Las concentraciones de N y P fueron ≥1.3 y 0.20%, excepto en las plantas de los sustratos H. brasiliensis y M. indica. Las concentraciones de K, Mg, Ca, Zn y B fueron inferiores a los valores recomendados en todos los tratamientos. La planta producida en el sustrato con aserrín de P. ayacahuite desarrolló las mejores variables morfológicas y de concentración de nutrientes; mientras que los valores más bajos se observaron en la planta con sustrato de M. indica. Lo cual se atribuye respectivamente, al menor y al mayor contenido de sales y fenoles en el aserrín de esas dos especies.

To evaluate individual and combined effect of captopril and telmisartan on systemic inflammation markers of hemodialysis (HD) patients. Randomized, double-blinded, controlled clinical trial. Patients on HD at least 2 months, with arteriovenous fistula, were randomly allocated to groups: (1) captopril/placebo (N 13); (2) telmisartan/placebo (N 13); (3) captopril + telmisartan (N 12); or (4) placebo/placebo (N 12). During 3 months, patients received oral drugs as follows: captopril 50 mg/day, telmisartan 80 mg/day or placebo. Patients excluded if they had conditions or were on drugs potentially influencing on inflammation. Clinical and biochemical evaluations were performed monthly. Serum tumor necrosis factor alpha (TNFα), interleukin 6 (IL-6), and C-reactive protein (CRP) were measured at 0, 1 and 3 months. Baseline, demographic, clinical and biochemical variables were comparable between groups. Baseline versus final inflammatory markers were: captopril/placebo TNFα, 2.47 (0.1–4.5) versus 1.73 (0.3–3.8) pg/ml; IL-6, 17.03 (7.2–23) versus 7.90 (0.7–19) pg/ml; CRP, 4.21 (1.6–18) versus 5.9 (3.0–28) mg/l; telmisartan/placebo TNFα, 3.03 (2.3–4.6) versus 1.70 (1.2–2.0) pg/ml; IL-6, 14.10 (5.5–23) versus 9.85 (6.2–13) pg/ml; CRP, 5.74 (2.1–13) versus 10.60 (1.5–27) mg/l; captopril + telmisartan TNFα, 1.43 (0.7–5.4) versus 0.40 (0.1–2.1) pg/ml; IL-6, 10.05 (4.9–23) versus 4.00 (0.7–7.7) pg/ml (p placebo/placebo TNFα, 3.13 (1.6–5.6) versus 1.64 (1.6–2.3) pg/ml; IL-6, 8.12 (5.4–16) versus 7.60 (2.4–15) pg/ml; CRP, 5.23 (1.9–16) versus 3.13 (1.5–18) mg/l. Monotherapy with captopril or telmisartan display a trend, but their combined treatment significantly decreased serum levels of IL-6. No remarkable changes on TNFα and CRP were observed.

Introduction: The production of seedlings in containers implies the risk of deforming the root. This damage persists and increases after outplanting causing negative effects on the plants. Objective: To evaluate outplanting performance of Pinus patula Schltdl. & Cham. as an effect of root pruning and containers used in the nursery. Materials and methods: Nine-month-old seedlings were grown in three 170 cc containers: plastic tray, polystyrene tray and grid with containers with 54, 77 and 42 cavities, respectively. The cavities were impregnated with copper hydroxide to encourage chemical root pruning; additionally, an aerial root pruning treatment was included (containers with lateral openings). Survival and growth of P. patula were evaluated under field conditions during two years in 72 plants per treatment, randomly distributed in six blocks or replications. Results and discussion: Pruned and unpruned plants showed significant differences (P ≤ 0.05) in survival (89 vs. 79 %), height (154.0 vs. 147.1 cm) and relative annual growth rates of diameter (0.97 vs. 0.93 cm·cm-1·year-1) and height (0.97 vs. 0.92 cm·cm-1·year-1). Plants in plastic containers and polystyrene trays had the best growth and survival rates. The interaction container*pruning was not significant. In spite of starting with the lowest sizes, the plants in containers designed for aerial root pruning had similar characteristics to those grown in the same containers with and without chemical root pruning. Conclusion: Root pruning favored survival and growth of P. patula after outplanting and had a greater effect than the type of container used.

Triggering receptor expressed on myeloid cells (TREM)-1 is a potent and early amplifier of the inflammatory response expressed on neutrophils and monocytes/macrophages. TREM-1, and its soluble form (sTREM-1), are increased in sepsis and other noninfectious inflammatory conditions. However, virtually no data are available in kidney disease. To determine serum sTREM-1 and its associated variables in patients on hemodialysis (HD), cross-sectional study including 264 HD patients and 148 controls. sTREM-1 was measured by quantitative sandwich enzyme immunoassay; soluble tumor necrosis factor receptor-1 (sTNF-R1), interleukin-6 (IL-6), and C-reactive protein (CRP) were also measured. All inflammation markers were significantly higher in HD patients than controls. Median (IQR) sTREM-1 was 1,006 (613-1,650) pg/mL but undetectable in controls. Considering only HD patients, sTREM-1 was positively correlated with IL-6 (r = 0.19, p = 0.008), and its levels were significantly higher in patients with arteriovenous fistula than in those with temporary catheter (1,226 vs. 743 pg/mL), in patients with 3 HD sessions/week than in those with 2 sessions/week (1,150 vs. 646 pg/mL), and in patients with >1 year on HD than in those with ≤1 year (1,100 vs. 948 pg/mL), whereas they were not different regarding age or presence of infection. Serum sTREM-1, sTNF-R1, IL-6, and CRP were higher in HD patients compared to controls. In HD patients, sTREM-1 displayed higher levels in individuals with arteriovenous fistula, 3 sessions/week and longer vintage, but not in those with infection or older age; in multivariate analysis, only the first two variables significantly predicted higher sTREM-1 levels.

Obesity is clearly associated to kidney disease in adult population; however, there is scarce evidence in children and adolescents. The aim was to compare frequency of renal damage according to the presence of overweight-obesity in children and adolescents, as well as to compare nutritional and biochemical risk factors, according to the presence of kidney alterations.Cross-sectional study; 172 children and adolescents, 6-16 years old, without malnutrition, diabetes mellitus, hypertension and independent comorbid conditions associated to obesity or kidney disease, as well as transitory causes of microalbuminuria (MA) from a Primary Health-Care Unit were included. Clinical, biochemical, anthropometric and dietetic evaluations were measured in all subjects; subsequently they were classified as normal weight, overweight and obesity groups according to sex- and age-adjusted body mass index (BMI). Glomerular filtration rate (GFR, estimated by Schwartz equation) and albuminuria (albumin/creatinine ratio) were determined. Presence of kidney alterations was measured as decreased GFR (90 mL/min/1.73mCompared with controls, subjects with overweight-obesity had significantly (P.05) abdominal obesity (0 vs 69%), hypertension (19 vs 26%), hypertriglyceridemia (11 vs 47%), high low-density lipoprotein cholesterol (2 vs 8%) and low high-density lipoprotein cholesterol (HDL-cholesterol; 2 vs 28%), hyperuricemia (11 vs 28%) and hyperinsulinemia (8 vs 70%). Hyperfiltration and MA were present in 5 and 4 subjects with overweight/obesity, respectively, whereas decreased GFR was present in only 1 subject with obesity. Normal weight subjects had no kidney alterations. In multivariate analysis, kidney alterations were significantly predicted by higher BMI and lower HDL-cholesterol.Kidney alterations were observed only in subjects with overweight (3.6%) and obesity (9.9%), who additionally, displayed cardiometabolic and kidney disease risk factors more frequently than normal weight subjects.

The economy of a country is exposed to disruptions caused by natural and man-made disasters. Here we present a set of probabilistic risk indicators, the Average Annual Loss (AAL) and the Loss Exceedance Curve (LEC), regarding to production, employment, Gross Domestic Product (GDP), Gross Regional Product (GRP), export volume, inflation, tariff revenue, among others, due to earthquakes. All indicators are computed using a systematic probabilistic approach, which integrates the seismic risk assessment with spatial computable general equilibrium models, both robust and well-known frameworks used worldwide in their respective fields. Our approach considers the induced damage and frequency of occurrence of a vast collection of events that collectively describe the entire seismic hazard of a country, giving us a better and more complete understanding of the full consequence of earthquakes. We illustrate this approach with an example developed for Chile.

The tropical climate present in the Yucatan Peninsula is one of the most aggressive environments found in Mexico, which results in many concrete structures being affected by corrosion. Several types of primers, which are locally available, are used as prevention and/or repair methods for reinforcement steel found in concrete structures. Nonetheless, such primers are not designed to be used under alkaline environmental conditions. The objective of this investigation was to evaluate the efficiency of these primers used to repair concrete columns of buildings exposed to a coastal marine environment in southeast Mexico. The repair method used involved the following steps: removal of the old concrete, cleaning the rebar with a brush, applying primer to the reinforcement steel, and finally applying bonding agent and new concrete cover. The electrochemical behavior of repaired and adjacent (non-repaired) zones was monitored based on electrochemical techniques with the use of a commercially confined-curr...

A new sample treatment is proposed based on a partial wet digestion in closed reactors assisted by microwaves for wear metal determinations by flame atomic absorption spectrometry (FAAS). It is rapid, precise and sensitive and allows the use of inorganic standards. Problems concerning solubility have been overcome with mixed solvents. The repeatability, stability, calibration curve and limit of detection were established. Six samples, with different degree of wear were analyzed for Fe, Cu, Pb and Cr by FAAS using the procedure proposed and other sample treatment procedures from the literature. Pb and Cr were not found in all samples. The one-way analysis of variance for Fe applied to each sample confirms the need of an acid attack and the importance of HCl for the digestion. The results obtained for Cu led us to use a two-way analysis of variance for all the samples considering the preparation procedures and the samples as variation sources. It showed no significant differences for the preparation procedures used. Therefore, treatments implying the use of acids are recommended when several wear metals are analyzed. On the other hand, the differences between the simple dilution and the procedures, implying the dissolution of metallic particles is an index to predict an imminent engine failure.

Several studies have shown the importance of organic material in the formation and stability of soil aggregates. The organic matter of soil (SOM) is affected among other factors by the application of farmyard waste and compost, as well as tillage and crop rotation. This paper examines the aggregation and stability of a sandy soil (Haplic Fluvisol) in the valley of Mexico when treated with either 40 Mg ha−1 of compost or urea (80 kg ha−1 of N) and sown to amaranth (Amaranthus hypochondriacus L.) under dryland conditions. The application of compost resulted in a significantly larger proportion of aggregates in the fractions >1 mm (1.0–2.0, 2.0–2.3, 2.3–4.7 mm) than in the smaller fraction ( 1 mm in the compost treatment was not higher than in contrasting treatments which did not include organic matter. Compost, which was applied under drought conditions, did not increase the aggregate stability of the soil probably because of the restricted transformation of the compost and microorganism activity.

La investigación sobre la magnitud y forma en que la cobertura vegetal controla la tasa de erosión del suelo en sistemas agroforestales es escasa. El objetivo de esta investigación fue analizar la relación entre la cobertura vegetal y la pérdida de suelo por erosión hídrica para proponer valores del factor cobertura y manejo (Factor C) de la Ecuación Universal de Pérdida de Suelo (EUPS) en diferentes sistemas agroforestales de café bajo sombra. Mediante análisis de regresión, fueron analizados datos provenientes de cinco microcuencas ubicadas en una región tropical de Veracruz, México. Las coberturas arbustiva y por mantillo ajustada por su espesor, mostraron mejores relaciones exponenciales congruentes con la tasa de pérdida de suelo (R2 = 0.70 y R2 = 0.87). El factor cobertura arbustiva y por mantillo en sistemas agroforestales de café bajo sombra (Cam) propuesto como factor sustituto del Factor C en la EUPS, explicó 68% de la variación de la pérdida de suelo. El intervalo de valores del Factor Cam varió entre 0.02 y 0.003 para sistemas agroforestales de café bajo sombra, valores mayores al valor más pequeño correspondiente a tierras forestales no disturbadas y menores al valor más grande correspondiente a potreros, praderas permanentes y tierras ociosas cubiertas por vegetación.

La calidad del fruto de tomate (Solanum lycopersicum L.) es afectada por variaciones genotípicas, condiciones climáticas, y el sistema de producción empleado. El objetivo de este estudio fue evaluar la calidad física y química del fruto de tomate producido en hidroponía y tezontle como sustrato en cuatro tamaños de partícula: 3-5, 5-10, 10-20 y 20-30 mm de diámetro (tratamientos T1, T2, T3 y T4); mezclado con polvo y fibra de coco (PFC) en proporción 3:1. Se usaron contenedores de plástico con 24 L de sustrato en los cuales se trasplantaron tres plántulas de tomate. Durante el ciclo de cultivo de octubre de 2009 a abril de 2010, las plantas se regaron diariamente por goteo. La conductividad eléctrica (CE) y pH de la solución nutritiva en contacto con la raíz se monitoreó mensualmente. El diseño experimental fue completamente al azar, con tres contenedores por unidad experimental y cinco repeticiones por tratamiento. Se usaron frutos maduros en los análisis de: sólidos solubles totales (SST), acidez titulable (AT), relación SST/AT, CE, pH, porcentaje de jugo, firmeza y color (luminosidad, hue y croma). Se realizó un análisis de varianza y se usó la prueba de Tukey DHS (p0.05) para comparar las medias de los tratamientos. Los resultados mostraron que el tamaño de partícula de tezontle mezclado con PFC (3:1) no afectó (p0.05) los SST, AT, relación SST/AT, CE, y croma del fruto, pero sí hubo diferencias (p0.05) en el pH y porcentaje de jugo, la luminosidad, hue y la firmeza del fruto. Por el suministro de agua, fácilmente disponible, se generó salinidad y alcalinidad en el sustrato, los cuales además de la temperatura, influyeron en los atributos de calidad fisicoquímica del fruto de tomate.

This study compared the effect of enalapril versus placebo on serum tumor necrosis factor (TNF)-alpha, interleukin (IL)-6, and C-reactive protein (CRP) in hemodialysis in a randomized, double- blinded, controlled clinical trial. Patients without infection or antiinflammatory drugs were randomly allocated to a study (n = 13, enalapril, 20 mg/day) or control (n = 12, placebo) group; all had arteriovenous fistula. Serum TNF-alpha, IL-6, and CRP were measured at 0, 1, and 3 months. Systolic blood pressure (baseline vs. final) was 151 +/- 25 vs. 135 +/- 19 mm Hg (p < 0.05) in the study group and 154 +/- 21 vs. 144 +/- 27 mm Hg in control group; diastolic blood pressure was 86 +/- 9 vs. 76 +/- 13 and 91 +/- 16 vs. 81 +/- 18 mm Hg, respectively; median (percentiles 25%-75%) IL-6 (baseline vs. final) was 4.2 (3-8) vs. 4.1 (2-9) pg/mL and 6.3 (3-9) vs. 6.7 (3-8) pg/mL; and CRP was 1.9 (1-7) vs. 3.0 (1-12) mg/L and 4.7 (1-16) vs. 3.9 (2-16) mg/L, respectively. TNF-alpha was detected in only two patients. Enalapril significantly reduced blood pressure in hemodialysis patients, but it did not decrease IL-6 and CRP compared with placebo.

"Se describe un método para resolver un problema de interpolación espacial. Los datos son funciones de transferencia que describen las amplificaciones relativas del movimiento en la superficie del terreno del valle de México. Estas funciones se han obtenido a partir de los espectros de Fourier de acelerogramas producidos por varios temblores y registrados en decenas de sitios en las zonas de terreno firme, transición y lago. Se plantea un esquema estadístico para restringir la interpolación espacial de las funciones de transferencia mediante el uso de las técnicas de regresión bayesiana. Ello permite hacer una incorporación formal de la información que se tiene acerca de los efectos de sitio en la respuesta dinámica del terreno. Esta formulación suministra soluciones más estables y racionales que las que se obtendrían al seguir esquemas de regresión convencionales para la interpolación espacial de datos geofísicos. La utilidad práctica del enfoque propuesto es que permite cuantificar las amplificaciones dinámicas en sitios donde no hay instrumentos."