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Presentar resultados preliminares del tratamiento con radioterapia estereotáctica extracraneal en metástasis hepáticas, tumores pulmonares y otras lesiones metastásicas. Se describe método terapéutico y se presenta un análisis prospectivo de 25 pacientes tratados en el servicio de radioterapia la Trinidad con esta modalidad de radioterapia de alta precisión, desde marzo de 2009. Se utilizó un acelerador lineal Varian® IX versión Trilogy con equipo de imágenes incorporado. Las dosis de radioterapia oscilaron entre 60 Gy en 3 fracciones a 44,5 Gy en 10 fracciones. El tiempo de seguimiento osciló de <1 mes a 16 meses. Se incluyeron un total de 25 individuos (44 lesiones); 14 pacientes con metástasis hepáticas, 5 con metástasis pulmonares (3 de ellos también recibieron tratamiento por metástasis hepáticas), 4 con tumores primarios de pulmón, 2 con metástasis vertebrales y 3 con otras lesiones secundarias. La tolerancia al tratamiento fue en general satisfactoria, sin complicaciones severas. Se observó estabilización o regresión parcial de las lesiones en 17 pacientes, persistencia o progresión local en 3 pacientes. En 13 individuos la enfermedad a distancia permaneció estable y en 10 ocurrió progresión de la misma, durante este tiempo limitado de seguimiento. Cuatro pacientes han fallecido con enfermedad. La radioterapia extracraneal estereotáctica es una modalidad terapéutica novedosa, con gran potencial en el manejo multidisciplinario de las enfermedades neoplásicas. Los resultados preliminares de este trabajo, demuestran su efectividad, seguridad y la factibilidad de su aplicación en nuestro país

Present the preliminary results obtained with stereotactic body radiation therapy in liver metastases, pulmonary tumors and other metastatic lesions. Treatment is described, presenting a prospective analysis of 25 patients treated in La Trinidad Radiation Therapy Service since March 2009. Patients were treated using a dual energy IX Varian® linear accelerator Trilogy version, with on board imaging. Doses of radiation varied from 60 Gy in 3 fractions to 44.5 Gy in 10 fractions. Follow up time varied from < 1 month to 16 months. Total of 25 patients were included in the study (44 lesions); 14 patients with liver metastases, 5 with lung metastases (3 of them also received treatment for liver metastases), 4 primary lung tumors, 2 vertebral metastases, and 3 with other metastatic lesions. Treatment was in general well tolerated with no serious complications. Partial regression or stabilization of the treated lesions occurred in 17 patients, persistence or local progression was seen in 3 patients. In 13 individuals there was no appearance of new metastatic disease and 10 showed progression of distant disease, during this limited follow up time. Four patients have died with disease. Stereotactic body radiation is a novel high precision radiation therapy technique with a great potential in the multidisciplinary management of patients with neoplastic disease. The preliminary results of this study and the review of the literature support the safety, and effectiveness of this treatment modality and the feasibility of employing in Venezuela

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The ion exchange equilibrium of Pb(II) on clinoptilolite modified with NH(4)Cl and NaCl can be represented by two types of isotherms. The first one is the ion exchange isotherm based upon the constant of thermodynamic equilibrium for the ion exchange reaction; however, the fitting procedure for this isotherm can be very tedious due to all the calculations involved and additional thermodynamic data. The second one is the Langmuir isotherm. The use of the Langmuir isotherm to represent ion exchange equilibrium has increased in recent last years since it adequately fits the equilibrium data and, furthermore, its calculation is much simpler. A comparison between the two isotherms showed that they fitted the experimental data reasonably well, but the Langmuir isotherm is much simpler and easier to use.

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OBJECTIVES: Provision of calcium-fortified foods may represent an important component of improving the calcium intake of children. We sought to determine whether the addition of calcium to cereal would have a net positive effect on calcium absorption without decreasing iron absorption. METHODS: Twenty-seven children, 6 to 9 years of age, were provided two servings per day (30 g of cereal per serving) of either a low (39 mg/serving) or fortified (156 mg/serving) calcium-containing cereal product for 14 days. Calcium absorption was measured by using stable isotopes added to milk (extrinsically labeled) and to the calcium-fortified cereal (intrinsically labeled). RESULTS: Fractional calcium absorption from the fortified cereal was virtually identical to that from milk. Fractional absorption of calcium from milk did not differ significantly when given with enriched or low-calcium-containing cereal. Total calcium absorption increased from 215 +/- 45 mg/d to 269 +/- 45 mg/d with the addition of the calcium-fortified cereal (P <.001). Iron absorption was similar when children received the calcium-fortified cereal or unfortified cereal. CONCLUSIONS: The addition of a moderate amount of calcium to a cereal product was beneficial to calcium absorption and did not interfere with iron absorption. Use of calcium-fortified food products may be considered a practical approach to increasing the calcium intake of children.

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Morphological variation was analyzed in wild, managed in situ, and cultivated populations of the columnar cactus Stenocereus stellatus in central Mexico. The purpose was to evaluate whether morphological divergence between manipulated and wild populations has resulted from domestication processes. Variation of 23 morphological characters was analyzed among 324 individuals from 19 populations of the Tehuacán Valley and La Mixteca Baja. Multivariate statistical analyses were used to group individuals and populations according to their morphological similarity. Individuals grouped according to the way of management and fruit characteristics were the most relevant for grouping. Within each region, sweet fruits with pulp colors other than red were more frequent in cultivated populations, where fruits were also larger, contained more and bigger seeds, and had thinner peel and fewer spines than fruits from wild individuals. Phenotypes common in managed in situ and cultivated populations generally occur in the wild but in lower frequencies. Artificial selection has thus operated by enhancing and maintaining desirable rare phenotypes in managed in situ and cultivated populations, causing divergent patterns of morphological variation from wild populations. Cultivation has caused the strongest level of divergence, but divergence has also been significant with management of wild populations in situ.

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Pollination biology, breeding system, and floral phenology of the columnar cactus Stenocereus stellatus were studied in wild, wild managed in situ and cultivated populations of central Mexico, in order to examine whether these aspects have been modified under domestication and whether they determine reproductive barriers between wild and manipulated individuals. Individuals of both wild and manipulated populations are self-incompatible, indicating that artificial selection has not modified the breeding system. Their pollination biology is also similar. Anthesis is mainly nocturnal, with a peak of nectar production between 0200 and 0400 when the stigma presents maximum turgidity. Nocturnal visitors are the effective pollinators. Nearly 75% of flowers exposed for nocturnal pollination set fruit, while none of the flowers exposed for diurnal pollination produced fruits. The bats Leptonycteris curasoae, L. nivalis, and Choeronycteris mexicana (Glossophaginae) are the most likely pollinators, and their time of foraging is synchronized with the time of nectar production and stigma receptivity in S. stellatus. Bats potentially move pollen over a considerable distance, so there is apparently no spatial isolation to prevent pollen exchange between wild and cultivated populations. Phenological studies showed that there are also no apparent temporal barriers. However, manual cross pollination failed between some domesticated and wild phenotypes, suggesting that gene flow between wild and cultivated populations might be limited by pollen incompatibility.

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A comparative study between an unburned evergreen sclerophyllousvegetation located in south-central Mexico under a wet-summer climate,with mediterranean regions was conducted in order to re-analyzevegetation and plant characters claimed to converge under mediterraneanclimates. The comparison considered floristic composition,plant-community structure, and plant characters as adaptations tomediterranean climates and analyzed them by means of a correspondenceanalysis, considering a tropical spiny shrubland as the external group.We made a species register of the number of species that resproutedafter a fire occurred in 1995 and a distribution map of the evergreensclerophyllous vegetation in Mexico (mexical) under nonmediterraneanclimates.The Tehuacán mexical does not differ from the evergreensclerophyllous areas of Chile, California, Australia, and theMediterranean Basin, according to a correspondence analysis, whichordinated the Tehuacán mexical closer to the mediterranean areasthan to the external group.All the vegetation and floristic characteristics of the mexical, aswell as its distribution along the rain-shadowed mountain parts ofMexico, support its origin in the Madrean-Tethyan hypothesis of Axelrod.Therefore, these results allow to expand the convergence paradigm of thechaparral under an integrative view, in which a general trend to ariditymight explain floristic and adaptive patterns detected in theseenvironments.

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A study of 94 slugs, collected from urban and rural areas in and around Léon, Nicaragua, was carried out in order to confirm the role of Vaginulus plebeius as an intermediate host of Angiostronglylus costaricensis. Third-stage larvae of A. costaricensis were obtained from these molluscs. Some of these larvae were then orally inoculated into two laboratory-bred rats Sigmodon hispidus and adult worms of A. costaricensis were recovered two months later. The infection rate of these slugs ranged from 4% in urban areas to 85% in rural areas. These data suggest that contamination to man is a major risk especially in rural areas and that abdominal angiostrongyliasis could be a health problem in Nicaragua.

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El benfluorex, un hipolipemiante ampliamente conocido, ha demostrado, mediante un estudio abierto en una muestra ecuatoriana, sus propiedades al hacer descender los niveles de colesterol total, triglicéridos y LDL-C en forma significativa e incrementar los niveles del HDL-C también significativamente. Todo esto redunda en la disminución del riesgo aterosclerótico

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