Toxic Hazards Research Unit

The activities of the Toxic Hazards Research Unit (THRU) for the period of June 1970 through May 1971 reviewed. Modification of the animal exposure facilities primarily for improved human safety but also for experimental integrity and continuity are discussed. Acute toxicity experiments were conducted on hydrogen fluoride (HF), hydrogen chloride (HCl), nitrogen dioxide (NO2), and hydrogen cyanide (HCN) both singly and in combination with carbon dioxide (CO). Additional acute toxicity experiments were conducted on oxygen difluoride (OF2) and chlorine pentafluoride (ClF5). Subacute toxicity studies were conducted on methylisobutylketone and dichloromethane (methylene dichloride). The interim results of further chronic toxicity experiments on monomethylhydrazine (MMH) are also described

Toxic Hazards Research Unit annual technical report, 1969 Final report, Jun. 1968 - May 1969

Apollo materials toxicity screening tests and effects of ethylene glycol, monomethylhydrazine, NF3, OF2, and ClF

Continuous animal exposure to dichloromethane

Continuous exposures of dogs, monkeys, rats and mice to 5000 ppm and 1000 ppm of dichloromethane vapor (CH2Cl2) produced severe toxic effects on dogs, rats and mice. Dogs died after 3 weeks exposure to 1000 ppm and after 6 weeks exposure to 5000 ppm. Thirty percent of the mice also succumbed during four weeks exposure to 5000 ppm CH2Cl2. Although rats survived 14 weeks exposure to 5000 ppm, they experienced subnormal weight gains. Significant gross and histopathological hepatic lesions were noted in all 3 species at death or experimental termination in 14 weeks. In addition, rats showed abnormal kidney histopathology. Fat stains disclosed mild fatty increase in monkey livers after 14 weeks exposure to 1000 ppm CH2Cl2

Migration costs and observational returns to migration in the developing world

Recent studies find that observational returns to rural-urban migration are near zero in three developing countries. We revisit this result using panel tracking surveys from six countries, finding higher returns on average. We then interpret these returns in a multi-region Roy model with heterogeneity in migration costs. In the model, the observational return to migration confounds the urban premium and the individual benefits of migrants, and is not directly informative about the welfare gain from lowering migration costs. Patterns of regional heterogeneity in returns, and a comparison of experimental to observational returns, are consistent with the model’s predictions

Effect of 90-day continuous exposure to methylisobutylketone on dogs, monkeys and rats

Continuous exposure of rats, dogs and monkeys to 410 mg/cu M methylisobutylketone vapor (MIBK) was conducted to evaluate the provisional spacecraft exposure limit of 20 ppm established by the Space Science Board in 1968. The exposure, conducted in a simulated space cabin environment, did not produce any measurable changes in dogs or monkeys. Rats developed hyaline droplet nephrosis within 2 weeks of exposure which was reversible upon removal from the MIBK even after 90 days. The data obtained indicated that the 60-minute emergency exposure limit of 100 ppm and the 90- and 1000-day provisional limits as established by the Space Science Board contain a wide margin of safety

Human Evolution: Genomic Gifts from Archaic Hominins

SummaryThe dispersal of humans throughout the world was accompanied by adaptations to local environments. New research shows that a previously identified haplotype of the EPAS1 gene, which allows Tibetans to live at high altitude, was inherited from archaic hominin ancestors

De la comida y de la guerra

Libro reseñado: Sancocho de mico. Relatos alimentarios de exsecuestrados políticos de las Fuerzas Armadas Revolucionarias de Colombia (farc-ep). Felipe Castilla Corzo. Universidad de La Sabana, Chía, 2018, 73 pp

De la comida y de la guerra

Libro reseñado: Sancocho de mico. Relatos alimentarios de exsecuestrados políticos de las Fuerzas Armadas Revolucionarias de Colombia (farc-ep). Felipe Castilla Corzo. Universidad de La Sabana, Chía, 2018, 73 pp

Mecanismos de procesamiento y presentación de antígeno en el sistema inmune

El sistema inmune muestra una gran versatilidad para reconocer y responder a una gran cantidad de macromoléculas extrañas o antígenos (Ag), eliminándolos y evitando a la vez reaccionar con constituyentes propios (1). Esto se realiza por la colaboración de linfocitos B (LB) y de linfocitos T (LT) que expresan un conjunto diferente de receptores. Aunque el receptor del LB (Inmunoglobulina) y el del LT (TCR) son similares en algunos aspectos y son codificados por secuencias de la misma familia de genes (2), difieren en la manera como reconocen el Ag. Mientras los LB reaccionan con el Ag en forma nativa, los LT son incapaces de discriminar entre la forma nativa y la denaturada (3)