Facultad de Medicina

Since 1982, Ehrlichia platys infection has been diagnosed in canines from Venezuela by the use of buffy coat smears. In 1992, ehrlichia-like bodies were observed in platelets from a severely ill girl by light microscopy. The patient was seropositive to E. chaffeensis by the indirect fluorescent antibody test (IFAT). Tetracycline was administered and the patient recovered. More than 400 cases with such intra-platelet organisms have been studied at this laboratory over the past 6 years, and all the patients had a good response to the treatment. To determine whether the organisms in human blood platelets were truly platelet ehrlichiae, IFAT and transmission electron microscopy (TEM) studies were undertaken in four patients. Light microscopic examination of blood samples revealed the dense organism inside platelets, and a great reactivity of the blood cells. Sera from the four patients were seronegative against E. chaffeensis and E. platys antigens. Three of four samples contained the intra-platelet organisms when examined by TEM. Electron microscopy showed platelets with vacuoles containing pleomorphic organisms. These organisms had a thickened membrane, an electron-translucent inner area and an electron-dense granular component in the periphery. An abundant electron-dense material was observed surrounding them. The ultrastructure of such micro-organisms has not been reported previously. Based on the similarity of many of their characteristics with rickettsiae, we suggest that the microorganisms found in the present study might belong to the family Rickettsiaceae.

La experimentacion biogenetica ha transformado la manera de ver la vida desde el develamiento del genoma humano. Ello le ha dado a la bioetica herramientas para la reflexion sobre la justificacion de los llamados Derechos Humanos de Cuarta Generacion. A partir de la doctrina de los dos niveles de Diego Gracia (1996), se adelanta parte del estudio de la Declaracion Universal sobre Bioetica y Derechos Humanos de UNESCO 2005, realizandose un intento de clasificacion de los principios en ella contenidos para la preservacion de la vida y de la dignidad del ser humano. Se argumenta que los dilemas que vienen acompanando la experimentacion biogenetica, permiten pensar en una doctrina juridica que intente proteger la dignidad del ser humano proveniente de la vulnerabilidad a la que se ve expuesta por motivos del descubrimiento del codigo genetico. A partir de una disquisicion sobre las llamadas generaciones de los derechos humanos, se reconstruyen los basamentos bioeticos de la cuarta gener...

To determine whether treatment with melatonin (MLT) improves the efficiency of immunization against Venezuelan equine encephalomyelitis (VEE) virus, mice were vaccinated with TC-83 VEE virus and treated daily with MLT (1 or 5 mg/kg) starting 3 days before immunization, until 10 days after. IgM antibody titers were determined at days 7, 14, and 21 post-immunization. IL-10 levels were assayed at day 14 postvaccination. Treatment with MLT increased antibody titers 14 days after the immunization. IL-10 levels also increased with MLT treatment (1 and 5 mg/kg). Mice were challenged with live VEE virus at day 21 postimmunization, and viral titers were plaque assayed in chicken embryo fibroblasts 4 days after the infection. Following this challenge brain virus levels were significantly reduced. The results suggest that MLT treatment enhances the efficiency of mice immunization against VEE virus.

Few investigations have been conducted on risk factors for Cryptosporidium infection in communities from developing countries. A study was conducted to determine the prevalence and risk factors for cryptosporidiosis in San Carlos island, Venezuela. A sample of 515 subjects (mean age ± SD: 21.4 ± 17.8 years) was surveyed. Single fecal specimens were collected and modified Ziehl-Neelsen carbolfuchsin staining of formalin-ether concentrate stools were examined for identification of the parasite. Infections with Cryptosporidium (67 of 515, 13%) were common. Prevalence of the parasite varied among sectors of the community; 34 of 67(50.7%) cases of cryptosporidiosis clustered in two sectors with extreme poverty. Variables strongly associated with a higher risk for the infection (p < 0.01) were residing in these sectors versus the remainder, living in a hut or small residence versus a brick or larger house, using an area of backyard rather than a toilet or latrine for defecation, and having contact with soil contaminated with human feces. Crowding was also a risk (p < 0.05). Contact with human feces contaminated-soil may be an important mode of transmission and poverty a predisposing factor for the infection.

When mice infected with the Venezuelan equine encephalomyelitis (VEE) virus were exposed to 2500 lux with a 12 h light: 12 h dark photoperiod, the serum levels of melatonin (MLT) remained constantly elevated. In mice exposed to 400 lux low levels of serum MLT were detected during the day and high levels during the night. An increase in the survival rate of the infected mice from 6 to 13 days after virus inoculation was also observed. The significant increment in the concentration of serum MLT produced by the high intensity light could be responsible for the longer survival rate of mice infected with the VEE virus.

l objetivo del estudio fue evaluar las características clínicas y metabólicas de riesgo para enfermedad cardiovascular (ECV) en fumadores activos jóvenes, por medio de una investigación prospectiva, interviniendo fumadores (grupo de estudio) y no fumadores (grupo control) de ambos sexos, con edad entre 18 a 28 años. Se registró historia de tabaquismo, presión arterial sistólica (PAS) y diastólica (PAD), frecuencia cardiaca, índice de masa corporal (IMC). Se midieron niveles plasmáticos de proteína C reactiva ultrasensible (PCRus), fibrinógeno, ácido úrico (AU) glicemia y perfil lipídico. La edad promedio fue de 20.88 ± 0.25 años, 61 (50.8%) eran fumadores y 59 (49.2%) no fumadores Los fumadores presentaron niveles más altos de IMC, PAS y PAD (p < 0.05) respecto a los no fumadores. La PCRus, AU, triglicéridos y VLDL también resultaron más elevados en los fumadores (p< 0.05). Es necesaria la intervención médica temprana en fumadores jóvenes aparentemente sanos.

l objetivo del estudio fue evaluar las características clínicas y metabólicas de riesgo para enfermedad cardiovascular (ECV) en fumadores activos jóvenes, por medio de una investigación prospectiva, interviniendo fumadores (grupo de estudio) y no fumadores (grupo control) de ambos sexos, con edad entre 18 a 28 años. Se registró historia de tabaquismo, presión arterial sistólica (PAS) y diastólica (PAD), frecuencia cardiaca, índice de masa corporal (IMC). Se midieron niveles plasmáticos de proteína C reactiva ultrasensible (PCRus), fibrinógeno, ácido úrico (AU) glicemia y perfil lipídico. La edad promedio fue de 20.88 ± 0.25 años, 61 (50.8%) eran fumadores y 59 (49.2%) no fumadores Los fumadores presentaron niveles más altos de IMC, PAS y PAD (p < 0.05) respecto a los no fumadores. La PCRus, AU, triglicéridos y VLDL también resultaron más elevados en los fumadores (p< 0.05). Es necesaria la intervención médica temprana en fumadores jóvenes aparentemente sanos.

Since 1978, polyculture experiments of pompano (Trachinotus carolinus) and shrimp have been conducted in the Centro de Investigaciones Científicas, Universidad de Oriente, Venezuela. Experiments are carried out in circular concrete ponds (28 m2) with running seawater (salinity 37–39 ppt and temperature 26.4–30.9°C) and constant aeration. In the first experiment (September-December 1978) pompano and shrimp were stocked at a density of 10/m2 and were fed with Tivela mactroides (Mollusca, Pelecipoda) “guacuco” pellet of 60% crude protein. Pompano 0.22±0.1 g reached after 75 days 40.6±25.6 g with food conversion of 6.59 and 17.14% survival; shrimp 1.3±0.4 g reached a weight of 5.7±0.9 g and 2.68% survival during 75 days. The common food conversion was 7.57.The second experiment (June-August 1981) was carried out in tanks with a false bottom. Pompano and shrimp were stocked at densities of 5 and 10/m2 respectively, and were fed with a pellet named GSCA (42.8% crude protein). Pompano 4.0±1.1 g reached 62.1±10.3 g after 75 days of culture, the food conversion and survival being 3.1 and 64.29%, respectively. Shrimp stocked at 3.6±0.6 g reached 8.9±1.8 g after 75 days, and feed conversion was 10.7 with 54% survival. The common feed conversion for pompano and shrimp was 6.6. After 75 days of culture the high mortality of pompano was due to the infection of branchial parasites, the protozoa Amyloodinium ocellatum and the trematode Bicotylophora trachinoti.

Un circuito RLC es un circuito eléctrico que consiste en un resistor, un inductor y de un condensador, conectada en serie o en paralelo. La parte RLC del nombre se debe a que esas cartas son los símbolos eléctricos habituales de resistencia, inductancia y capacitancia respectivamente. El circuito forma un oscilador armónico para la corriente y resonará de una manera similar como un circuito LC.