La centralización del capital: proceso determinante en la transnacionalización del capitalismo contemporáneo

Mientras diversas corrientes del pensamiento económico ven todavía a la libre competencia como el cimiento del capitalismo actual y a los monopolios u oligopolios como fallas de mercado, en este artículo se sostiene la hipótesis de que la competencia promueve los procesos de concentración de la producción y centralización del capital que dan origen a una fase monopolista del capitalismo en la que surgen grandes empresas, en forma de grupos financieros o conglomerados empresariales, que trascienden las fronteras nacionales y tienen capacidad para incidir en las condiciones que determinan el encuentro entre oferentes y demandantes. Este fenómeno no es exclusivo de los países ricos sino que también se presenta en países pobres caracterizados por un «capitalismo dependiente y tardío», sin libre competencia pero con una fuerte presencia de oligarquía financiera. La transnacionalización de empresas colombianas permite exponer un ejemplo práctico de lo anterior

Hepatitis A, B y D en Chocó

A study to compile and analyse the existing epidemiological information concerning hepatitis A, B and D in the Chocó department of Colombia was carried out from 1976-1993. One study reported a hepatitis A virus antibody prevalence of 85.7 per thousand, in a representative population sample. There was evidence of transmission amongst al1 age groups. In the same sample a hepatitis B surface antigen prevalence of 4.2 per thousand was found. Acute fulminant hepatitis foci for hepatitis D have been detected in the town of Riosucio in the Truandó-Salaquí region, where hepatitis B infection prevalence of 915 per thousand and 200 per thousand hepatitis B surface antigen prevalence was found. The main transmission axis is vertical-horizontal. The principal important transmission riskfactors in this area are: overcrowding, promiscuity, the 15-24 female age group and the evidence of transmission in any family member. Two foci of acute fulminant hepatitis have been identified in Bebaramá and Guarandó in the rural zone of Quibdó, hepatitis B infection prevalencies of 74% and 85% having been found. A study carried out with health personnel, whose objective was to identify groups most at risk, found infection prevalencies between 27% and 33%. Furthermore, hepatitis B sutface antigen prevalence was 13.3% and 13.6%, principally in nursing and laboratory personnel. Finally, integral solution alternatives were planned for hepatitis A and B based on health promotion activities, preventative measures (such as hepatitis B vaccination), vigilante and control.Se realiza una recopilación y análisis de la información epidemiológica existente sobre hepatitis A, B y delta en el departamento de Chocó en el período 1976-1993. En un estudio anterior, se informó una prevalencia de anticuerpos contra el virus de la hepatitis A de 85,7 por mil, en una muestra representativa de la población, con evidencia de transmisión en todos los grupos de edad; en la misma muestra, se encontró una prevalencia de antigeno de superficie de hepatitis B de 4,2/1.000. Se han detectado focos de hepatitisfulminante aguda por hepatitis delta en la región de Truandó-Salaquí, en el municipio de Riosucio, donde se encontró una prevalencia de infección por hepatitis B de 915/1.000 y una prevalencia de antígeno de superficie de hepatitis B de 200/1.000, El principal patrón de transmisión es vertical-horizontal. Los principales factores de riesgo de importancia en la transmisión en esa área son el hacinamiento, la promiscuidad, los grupos femeninos de 15 a 24 años y la evidencia de transmisión en algún miembro de la familia. En la zona rural de Quibdó, se han identificado dos focos de hepatitis fulminante aguda en las localidades de Bebaramá y Guarandó, encontrándose prevalencias de infección por hepatitis B de 74 y 85%. En un estudio realizado en personal de salud cuyo objetivo era identificar los grupos con mayor riesgo, se encontraron prevalencias de infección entre 27 y 33%; además, la prevalencia de antígeno de superficie de hepatitis B fue 13,3 a 13,6 %, principalmente en personal de enfermería y laboratorio. Finalmente, se plantean alternativas integrales de solución para hepatitis A y B basadas en actividades de promoción de la salud, medidas de prevención como la vacunación contra hepatitis B, la vigilancia y el control

Diagnóstico de malaria por el método de la PCR anidada

In 1998, 256.697 malaria cases were confirmed in Colombia, 132,712 of which were caused by Plasmodium falciparum, 121. 161 by, and 2,824 mixed infections. Consequently, the Malaria Program of the National Reference Laboratory initiated an evaluation of the nested polymerase chain reaction (PCR) technique for malaria diagnosis. This technique amplifies variable sequences present in the 18s small subunit ribosomal RNA (ssrRNA) genes of P falciparum and P vivax. The infected blood samples were collected in Quibdó (Chocó) from 102 febrile patients who requested malaria diagnosis; the presence of parasites was established by both PCR and microscopical examination of thick blood smears. In order to evaluate the nested PCR, the following criteria were adopted: precision, accuracy, detection treshhold, sensitivity, specificity, positive and negative predictive values and Kappa index. General sensitivity was 100%, with a sensitivity for P vivax of 96.7% and for P falciparum of 100%. General specificity and specificity for both species wore 100%. The general positive predictive value was 90.0%, for P vivax 77.0% and for P falciparum 66.1%. The general negative predictive value was 90.3%. 90.6% for P vivax and 94.3% for P falciparum. The general concordance (or Kappa index) was 1 and the species concordance was 0.96. The detection treshhold of parasite DNA was 10 fg/ul. One sample diagnosed as P. vivax by microscopy was determined as a mixed infection of P falciparum and P vivax by nested PCR. Nested PCR can be employed as a diagnostic tool in the following roles: (1) a screening method for large scale epidemiological trials, (2) in evaluations of the malaria control program in Colombia, (3) in detection of early or low levels of persistent parasiternia, possibly indicative of drug-resistant malaria, and (4) as a reference test for planned diagnostic trials.En 1998, se presentaron en Colombia 256.697 casos de malaria: 132.712 por Plasmodium falciparum, 121.161 por Plasmodium vivax y 2.824 infecciones mixtas. Dada esta situación, el Programa de Malaria del Laboratorio Nacional de Referencia se propuso evaluar la PCR anidada frente a la gota gruesa, como método alternativo para el diagnóstico de malaria. Se utilizó la reacción en cadena de la polimerasa (PCR) anidada para amplificar secuencias variables de genes de la subunidad ribosomal pequeña 18s (ssrARN) de P falciparum y P vivax. Para evaluar la PCR, se recolectaron 102 muestras de pacientes febriles en Quibdó (Chocó) y se determinó la presencia de parásitos tanto por PCR como por observación microscópica (gota gruesa). Los resultados de las dos pruebas se compararon entre sí. Los criterios de evaluación fueron: precisión, exactitud, limite de detección, sensibilidad, especificidad, valores predictivos positivo (VPP) y negativo (VPN) e índice kappa. La PCR anidada presentó una sensibilidad general del 100%: 96,7% para Pvivax y 100% para P falciparum. La especificidad general para P vivax y para P falciparum fue del 100%. El VPP general de la prueba fue del 90% y el VPN fue de 90.3%; para P vivax, el VPP fue de 77,0% y el VPN de 90.6%: para P falciparum, el VPP fue de 66,1% y el VPN de 94,3%. El índice kappa generaI fue de 1 y el de especie fue de 0,96. El límite de detección del ADN parasitario fue de 10 fg/ml. La PCR anidada detectó una muestra con infección mixta de P. vivax y P. falciparun que, por gota gruesa, dio resultado positivo para P. vivax. Se recomienda el uso de la PCR anidada como método de tamizaje en estudios epidemiológicos para la evaluación del Programa de Control Nacional de Malaria, en estudios orientados a detectar de manera temprana parasitemias en pacientes tratados cuya posible causa pueda ser la resistencia a los antimaláricos y como prueba de referencia para evaluar nuevos métodos diagnósticos

Encuesta seroepidemiológica de pian en la Costa Pacífica colombiana

Yaws has been endemic in the Pacific Coast of Colombia, but the actual prevalence is not known. For this reason we carried out a survey in the communities of this part of the countty where cases had been observed. The active search for cases was based on clinical observations of patients with dermatological disorders, to whom VDRL and FA-ABS tests were administered. The epidemiological survey included 4 intradomiciliary cases for each of the clinical patients detected and also 42 extradomiciliary cases. From a total of 1,830 persons examined, only 6 presented positive results for the VDRL and FTA-ABS tests, which represents a treponema infection prevalence of 0.3%. None of the clinically suspected yaw cases reacted positively to the mentioned tests. These findings permit us to conclude that yaws is not a public health problem in the Pacific Coast of Colombia, and that the sole use of clinical parameters induces to mistaken diagnosis.El pian ha sido endémico en la Costa Pacífica colombiana, pero actualmente su frecuencia real es desconocida, razón por la cual se realizó un estudio en las comunidades de esta zona del país donde se habían conocido casos de pian. Se hizo búsqueda activa de casos clínicos sospechosos a través de examen físico de personas con problemas dermatológicos; a todos ellos se les practicaron exámenes serológicos de VDRL y FTA-ABS. Por cada caso clínico sospechoso de pian, se estudiaron - por clínica y serologia - 4 contactos intradomiciliarios y 42 contactos extradomiciliarios. De las 1.830 personas examinadas, sólo 6 fueron reactivas a las pruebas de VDRL y FTA-ABS, lo cual representa una prevalencia de treponematosis de 0,3%. Ninguna de las pruebas serológicas fue reactiva en los casos clínicos sospechosos de pian. Esto nos lleva a concluir que, en la Costa Pacífica colombiana, el pian no es un problema de salud pública y que se registran como pian otras enfermedades cuando el diagnóstico tiene sólo bases clínicas

Evaluación de campo de una prueba rápida para el diagnóstico de malaria

Between November 1999 and April 2000, a malariaoutbreak occurred in the state of La Guajira, Colombia; 5.687 cases were diagnosed -3,401 as P falciparum, 2,256 as P vivax and 30 as mixed infections. The conditions of location and case number were considered favorable for the application and evaluation of a rapid diagnostic field test. Malaria diagnosis obtained by the rapid immunocromatographic test (OptiMAL) and thick blood smear were compared in the municipalities of Dibulla, Manaure and Riohacha. The treatment of each patient was based on the rapid test result, but whenever the two methods disagreed, the thick bood smear results were given priority in decisions to modify the initial treatment. Two hundred thitiy-one finger-prick blood samples were processed. The general sensitivity and specificity of OptiMAL were 98.7% and 99.3%, respectively. The sensitivity and specificity for P falciparum were 98.1% and 76.9%. The sensitivity and specificity for F1 vivax were 90.9% and 100%. The concordance index was 0.98, the positive predictive value, 98.7% and the negative predictive value, 99.3%. These results suggest that the rapid immunocromatographic test (OptiMAL) is a reliable alternative for malaria diagnosis under circumstances where rnicroscopical diagnosis is not possible.Entre noviembre de 1999 y abril de 2000 se presentó una epidemia de malaria en el departamento de La Guajira que alcanzó 5.687 casos, 3.401 causados por Plasmodium faiciparum, 2.256 por Plasmodium vivax y 30 casos diagnosticados como infección mixta. Dadas las caracteristicas propias del departamento de La Guajira y de la transmisión de malaria allí, se consideró que existían las condiciones favorables para usar una prueba rapida de diagnostico de campo. En este estudio se evaluó y comparó el diagnóstico por inmunocromatografía rápida con la gota gruesa como estándar de oro en los municipios de Dibulla, Manaure y Riohacha. La conducta con el paciente se basó en el resultado de la prueba rápida. Sin embargo, los resultados obtenidos en la gota gruesa se tuvieron en cuenta para modificar la conducta inicial con el paciente, en caso de que los resultados de las pruebas fueran discordantes. Se procesaron 231 muestras sanguíneas obtenidas por punción capilar. La sensibilidad y la especificidad generales del método inmunocromatográfico fueron de 98.7% y 99.3%. respectivamente, en tanto que para P falciparum fueron de 98.1% y 76,9%, y para P vivax de 90,9% y 100%. El índice de concordancia fue 0.98; el valor predictivo positivo, 98,7%, y el valor predictivo negativo, 99,3%. Los resultados obtenidos sugieren que la prueba inmunocromatográfica (OptiMal) es una alternativa adecuada para realizar el diagnóstico de malaria en lugares donde no se realiza el diagnóstico microscópico

Kerr-Schild ansatz in Einstein-Gauss-Bonnet gravity: An exact vacuum solution in five dimensions

As is well-known, Kerr-Schild metrics linearize the Einstein tensor. We shall see here that they also simplify the Gauss-Bonnet tensor, which turns out to be only quadratic in the arbitrary Kerr-Schild function f when the seed metric is maximally symmetric. This property allows us to give a simple analytical expression for its trace, when the seed metric is a five dimensional maximally symmetric spacetime in spheroidal coordinates with arbitrary parameters a and b. We also write in a (fairly) simple form the full Einstein-Gauss-Bonnet tensor (with a cosmological term) when the seed metric is flat and the oblateness parameters are equal, a=b. Armed with these results we give in a compact form the solution of the trace of the Einstein-Gauss-Bonnet field equations with a cosmological term and a different than b. We then examine whether this solution for the trace does solve the remaining field equations. We find that it does not in general, unless the Gauss-Bonnet coupling is such that the field equations have a unique maximally symmetric solution.Comment: 10 pages, no figures, references added. Last version for CQ

Prevalence of smoking and incidence of initiation in the Latin American adult population: the PLATINO study

Background: the PLATINO project was launched in 2002 in order to study the prevalence of chronic obstructive pulmonary disease (COPD) in Latin America. Because smoking is the main risk factor for COPD, detailed data on it were obtained. the aim of this paper was to evaluate the prevalence of smoking and incidence of initiation among middle-aged and older adults (40 years or older). Special emphasis was given to the association between smoking and schooling.Methods: PLATINO is a multicenter study comprising five cross-sectional population-based surveys of approximately 1,000 individuals per site in São Paulo (Brazil), Santiago (Chile), Mexico City (Mexico), Montevideo (Uruguay) and Caracas (Venezuela). the outcome variable was smoking status (never, former or current). Current smokers were those who reported to smoke within the previous 30 days. Former smokers were those who reported to quit smoking more than 30 days before the survey. Using information on year of birth and age of smoking onset and quitting, a retrospective cohort analysis was carried out. Smoking prevalence at each period was defined as the number of subjects who started to smoke during the period plus those who were already smokers at the beginning of the period, divided by the total number of subjects. Incidence of smoking initiation was calculated as the number of subjects who started to smoke during the period divided by the number of non-smokers at its beginning. the independent variables included were sex, age and schooling.Results: Non-response rates ranged from 11.1% to 26.8%. the prevalence of smoking ranged from 23.9% (95% CI 21.3; 26.6) in São Paulo to 38.5% (95% CI 35.7; 41.2) in Santiago. Males and middle-aged adults were more likely to smoke in all sites. After adjustment for age, schooling was not associated with smoking. Using retrospective cohort analysis, it was possible to detect that the highest prevalence of smoking is found between 20-29 years, while the highest incidence is found between 10-19 years. Age of smoking onset tended to decline over time among females.Conclusion: the prevalence of smoking varied considerably across sites, but was lower among countries with national anti-smoking campaigns.Univ Fed Pelotas, Pelotas, BrazilUniv Republica, Montevideo, UruguayInst Nacl Enfermedades Resp, Mexico City, DF, MexicoUniversidade Federal de São Paulo, São Paulo, BrazilPontificia Univ Catolica Chile, Santiago, ChileCent Univ Venezuela, Caracas, VenezuelaUniversidade Federal de São Paulo, São Paulo, BrazilWeb of Scienc

Target product profile for a test for the early assessment of treatment efficacy in Chagas disease patients: An expert consensus.

Six to 7 million people are estimated to be infected by Trypanosoma cruzi, the parasite causing Chagas disease. Thirty to 40% of them, i.e., 1.8 to 2.4 million people, will suffer cardiac disorders and/or digestive clinical manifestations if they are not treated early during the course of the infection [1, 2]. However, only a small fraction of patients are properly diagnosed and treated [3]. Current clinical guidelines recommend treating T. cruzi–infected people if they are asymptomatic or present early symptoms of the disease (Table 1) [4, 5]. Benznidazole (BNZ) and nifurtimox (NFX) are the first-line antiparasitic treatments currently available, both with long administration regimens (60 days) that can produce adverse side effects [6–8]. Despite the fact they are not 100% effective in patients with chronic disease [9–12], they are the only drugs currently registered, and the benefits of their administration have been confirmed in several clinical studies. Currently, clinical trials with new compounds, using alternative regimens that aim to maintain efficacy whilst reducing toxicity, are ongoing and could lead to new therapeutic opportunities and/or policy change

Controlo químico de infestantes

Uma planta é considerada infestante quando nasce espontaneamente num local e momento indesejados, podendo interferir negativamente com a cultura instalada. As infestantes competem com as culturas para o espaço, a luz, água e nutrientes, podendo atrasar e prejudicar as operações de colheita, depreciar o produto final e assegurarem a reinfestação nas culturas seguintes. Dado o modo de propagação diferenciado das diversas espécies de infestantes, com as anuais a propagarem-se por semente e as perenes ou vivazes a assegurarem a sua propagação através de órgãos vegetativos (rizomas, bolbos, tubérculos, etc.), assim, também o seu controlo quer químico, quer mecânico terá que ser diferenciado, ou seja, para controlar infestantes anuais será suficiente destruir a sua parte aérea, enquanto para controlar infestantes perenes teremos que destruir os seus órgãos reprodutivos. O controlo de infestantes poderá ser químico, através da utilização de herbicidas, ou mecânico pela utilização de alfaias agrícolas, tais como a charrua de aivecas, a charrua de discos, a grade de discos, o escarificador e a fresa. Quando a técnica utilizada na instalação das culturas é a sementeira directa, o controlo das infestantes terá que ser obrigatoriamente químico, enquanto se o recurso à mobilização do solo for a técnica mais utilizada (sistema de mobilização tradicional ou sistema de mobilização reduzida), o controlo das infestantes tanto poderá ser químico como mecânico. Neste trabalho iremos abordar apenas, o controlo químico de infestantes