Is premating isolation in Drosophila overestimated due to uncontrolled factors?

Sexual isolation in Drosophila is typically measured by multiple-choice mating tests. While many environmental variables during such tests are controlled by the researcher, there are some factors that are usually uncontrolled. We demonstrate, using Drosophila melanogaster and D. pseudoobscura flies, that the temperature of rearing, pre-adult density, and level of consanguinity, can all produce differences in mating propensity between genetically equivalent flies. These differences in mating propensity, in turn, can give rise to statistically significant results in multiple-choice mating tests, leading to positive isolation values and the artifactual inference of sexual isolation between populations. This fact agrees with a nonrandom excess of significant positive tests found in a review of the literature of Drosophila intraspecific mating choice. An overestimate of true cases of sexual isolation in Drosophila in the literature can, therefore, not be ruled out.

La ética de la investigación en seres humanos en debate / The ongoing debate on research involving human beings

La investigación en seres humanos permite mejorar el diagnóstico y el tratamiento de las enfermedades. Sin perjuicio de los beneficios indudables para la humanidad, se debe tener presente que la historia de este tipo de investigación muestra que cada vez que su práctica se separó de la reflexión moral y del control social, se produjeron hechos aberrantes y diversos atropellos a los derechos humanos (antes, durante y después de la Segunda Guerra Mundial). Actualmente se asiste a un vivo debate entre las tendencias favorables a una flexibilización ética, que permita abatir los tiempos y los costos de la experimentación, y las contrarias, que sostienen que es inaceptable permitir un doble estándar ético que convertiría a personas y poblaciones vulnerables en meros medios para el logro de un beneficio para la humanidad o la ciencia. El debate se centra en abrir la puerta o no al uso de placebo en ensayos clínicos controlados cuando existe un tratamiento conocido y en asegurarle o no a los participantes los beneficios de tratamientos sin costo. Hasta el momento, la legislación nacional en la materia (decreto 379/008) ha resistido la tendencia a la flexibilización. Pero el país no escapa al debate global en la materia. La revisión de las normativas éticas es un proceso necesario, producto de la reflexión ética permanente. Sin embargo, esta actualización no debe retroceder en los estándares éticos consensuados, priorizando la protección de los participantes de la investigación sobre cualquier otro interés. (AU)

Research involving human beings enables improvement of diagnosis and treatment of diseases. Without prejudice of its doubtless benefits for humanity, we need to bear in mind that historically, this kind of research proved that every time it moved away from moral reflection and social control, aberrant facts took place and several human rights were ran over (before, during and after World War II). Today, we witness the ongoing debate between trends that favor an increased ethical flexibility that allows better times and costs of research, and the opposite trends that believe a double ethical standard resulting in vulnerable people and populations being mere means for the accomplishment of benefits for humanity or science is unacceptable. The debate focuses on whether or not to open the door to the use of placebo in controlled clinical trials when there is a well known treatment, and whether or not to ensure participants are guaranteed the benefits of treatment for free. Until now, the relevant legal provisions in force (Decree 379/008) have endured the trend to increase flexibility.However, our country cannot ignore the global debate on this issue.Ethical regulations need to be revised through an ongoing ethical reflection. Notwithstanding this process, this update must not give up agreed ethical standards that prioritize the protection of participants in research over any other interest.

A pesquisa em seres humanos permite melhorar o diagnóstico e o tratamento das doenças. Sem perder de vista os óbvios benefícios para a humanidade, é importante lembrar que cada vez que sua realizaçäo se afastou da reflexäo moral e do controle social foram observadas praticas aberrantes e os direitos humanos näo foram respeitados (antes, durante e depois da Segunda Guerra Mundial). Atualmente se observa o debate entre os grupos favoráveis a flexibilizaçäo da ética, que permitiria reduzir os tempos e os custos das experiências y os grupos contrários que afirmam que é inaceitável permitir um padräo ético duplo que faria que as pessoas e populações vulneráveis se transformassem em um meio para alcançar benefícios para a humanidade e a ciência. O ponto central do debate é autorizar ou näo o uso de placebo em estudos clínicos controlados quando existe tratamento conhecido e garantir ou näo, aos participantes, os benefícios de tratamentos sem custo. Até agora a legislaçäo nacional (decreto 379/008) vem resistindo à tendência a flexibilizaçäo. Mas o país näo escapa do debate global sobre o tema. A revisäo das normas éticas é um processo necessário, resultado da reflexäo ética permanente.No entanto, esta atualizaçäo näo deve voltar atrás nos padrões éticos aprovados por consenso, dando prioridade aos participantes das pesquisas sobre qualquer outro interesse.

Resultados del tratamiento de la leucemia aguda mieloblástica del niño con trasplante de progenitores hematopoyéticos en primera remisión / Results of treatment of acute myeloid leukemia of children with bone marrow transplantation in first remission

Introducción: el pronóstico de la leucemia agudamieloblástica (LAM) en el niño ha mejorado en lasúltimas décadas. Estos avances son el resultado de laintensificación de los tratamientos de inducción y postremisión. Muchos grupos han investigado la utilidaddel trasplante de progenitores hematopoyéticos (TPH)en la LAM en primera remisión. El objetivo de esteestudio fue evaluar los resultados obtenidos con TPHalogénico y autólogo luego de dos tratamientos deconsolidación intensivos.Material y métodos: en el periodo entre enero de1997 y diciembre de 2006, 31 pacientes menores de15 años con LAM de novo fueron incluidos en elprotocolo LAM-CHPR. Después de uno o dostratamientos de inducción todos los pacientes enremisión completa (RC) recibieron dos tratamientos deconsolidación. Luego los pacientes con hermano HLAidéntico fueron planificados para ser sometidos a TPHalogénico, mientras aquellos sin donante, recibieronTPH autólogo.Resultados: veintinueve pacientes (93,6%) alcanzaronla RC tras uno (n=26) o dos (n=3) tratamientos deinducción. Dos pacientes tuvieron una muertetemprana. Otros cuatro pacientes tuvieron una muerterelacionada al tratamiento (MRT) debido acomplicaciones infecciosas durante la fase dequimioterapia. De los 25 pacientes que entraron en la fasede trasplante 24 recibieron TPH, cuatro alogénicos y 20autólogos. No hubo muertes relacionadas con el trasplante.Seis pacientes recayeron, todos pertenecientes al grupo delos TPH autólogos. Cuatro fallecieron por progresión de laenfermedad y dos fueron rescatados con un segundotrasplante de donante haploidéntico. La probabilidad desobrevida global (SG) y sobrevida libre de eventos (SLE)estimada a los 10 años postrasplante fue de 73,5%±9,4 y64,5%±10,2% respectivamente. En relación a todos lospacientes con intención de tratar incluidos en el protocolo,la probabilidad de SG y SLE estimada a los 10 años fue de56,6%±9,2 y 50%±9,0 respectivamente.Conclusiones (cont) (AU)

DISENTANGLING THE EFFECTS OF MATING PROPENSITY AND MATING CHOICE IN DROSOPHILA.

Incipient sexual isolation between genotypes, lines, or populations of the same species is commonly measured in Drosophila by choice tests. Results of these tests are known to be influenced, in an undetermined manner, by the mating propensity of competitors and by discriminatory factors during courtship. We have approached the problem by measuring male and female propensities in separate, independent tests, and by examining whether these estimates could explain the results of the choice tests. First, male and female choice tests were used to measure sexual isolation between populations of Drosophila melanogaster and between populations of D. simulans. Significant deviations from random mating occurred in 31 out of 48 tests, in agreement with the propensity values of the tested genotypes. We conclude that mating propensity instead of discrimination is directly involved in the estimation of sexual isolation in our populations, and advise against the application of male and female choice tests to assess intraspecific isolation without a proper knowledge of the mating propensities of competing individuals. Second, multiple choice tests were used to assess isolation between D. melanogaster populations. In examining the dynamics of matings throughout the test, we show that if competing individuals differ in mating propensities and tests are long enough to allow most matings to happen, a spurious sexual isolation can appear. We recommend that multiple choice tests be terminated once 50 percent of matings had been observed.

Occupation and smoking as risk factors for lung cancer: a population-based case-control study.

BACKGROUND: Lung cancer is associated with occupation, but not much is known about the influence exerted on risk by length of exposure and the joint effect of occupational exposure and tobacco on risk of lung cancer. METHODS: Through a population-based case-control study, we defined risk professions as those that have been associated previously with higher risk of lung cancer. RESULTS: The relative risk seems to increase linearly and significantly with the number of years spent in risk occupations, rising significantly by 28% for every 10 years in a risk profession. Should such occupations be combined with exposure to a smoking habit, then in the case of heavy smokers, a working career spanning 20 years or more in risk occupations would mean tripling the possibility of developing lung cancer from occupation. CONCLUSIONS: The high risks observed indicate a public health problem and indicate that joint exposure to risk professions and tobacco ought to be avoided. We must stress from these results the need for effective education for all workers.

Is premating isolation in Drosophila overestimated due to uncontrolled factors?

Sexual isolation in Drosophila is typically measured by multiple-choice mating tests. While many environmental variables during such tests are controlled by the researcher, there are some factors that are usually uncontrolled. We demonstrate, using Drosophila melanogaster and D. pseudoobscura flies, that the temperature of rearing, pre-adult density, and level of consanguinity, can all produce differences in mating propensity between genetically equivalent flies. These differences in mating propensity, in turn, can give rise to statistically significant results in multiple-choice mating tests, leading to positive isolation values and the artifactual inference of sexual isolation between populations. This fact agrees with a nonrandom excess of significant positive tests found in a review of the literature of Drosophila intraspecific mating choice. An overestimate of true cases of sexual isolation in Drosophila in the literature can, therefore, not be ruled out.