Genotoxicity of neutrons in Drosophila melanogaster. Somatic mutation and recombination induced by reactor neutrons.

This paper describes the observation of a direct relationship between the absorbed doses of neutrons and the frequencies of somatic mutation and recombination using the wing somatic mutation and recombination test (SMART) of Drosophila melanogaster. This test was used for evaluating the biological effects induced by neutrons from the Triga Mark III reactor of Mexico. Two different reactor power levels were used, 300 and 1000 kW, and two absorbed doses were tested for each power level: 1.6 and 3.2 Gy for 300 kW and 0.84 and 1.7 Gy for 1000 kW. A linear relationship was observed between the absorbed dose and the somatic mutation and recombination frequencies. Furthermore, these frequencies were dependent on larval age: In 96-h-old larvae, the frequencies were increased considerably but the sizes of the spots were smaller than in 72-h-old larvae. The analysis of the balancer-heterozygous progeny showed a linear absorbed dose- response relationship, although the responses were clearly lower than found in the marker-trans-heterozygous flies. Approximately 65% of the genotoxicity observed is due to recombinational events. The results of the study indicate that thermal and fast neutrons are both mutagenic and recombinagenic in the D. melanogaster wing SMART, and that the frequencies are dependent on neutron dose, reactor power, and the age of the treated larvae.

Genetic effects induced by neutrons in Drosophila melanogaster I. Determination of absorbed dose.

A method to obtain the absorbed dose in Drosophila melanogaster irradiated in the thermal column facility of the Triga Mark III Reactor has been developed. The method is based on the measurements of neutron activation of gold foils produced by neutron capture to obtain the neutron fluxes. These fluxes, combined with the calculations of kinetic energy released per unit mass, enables one to obtain the absorbed doses in Drosophila melanogaster.

Treatment of Bolivian hemorrhagic fever with intravenous ribavirin.

Bolivian hemorrhagic fever (BHF) is a potentially severe febrile illness caused by Machupo virus (family Arenaviridae). Initial symptoms include headache, fever, arthralgia, and myalgia. In the later stages of this illness, patients may develop hemorrhagic manifestations including subconjunctival hemorrhage, epistaxis, hematemesis, melena, and hematuria, as well as neurological signs including tremor, seizures, and coma. During the BHF epidemics of the 1960s, convalescent-phase immune plasma from survivors of BHF was administered to selected patients infected with Machupo virus. However, there is currently a paucity of survivors of BHF who can donate immune plasma, and there is no active program for collection and storage of BHF immune plasma; therefore, we had the opportunity to offer intravenous ribavirin to two of three patients with this potentially life-threatening infection. One patient with laboratory-confirmed Machupo virus infection who received ribavirin recovered without sequelae, as did a second patient with suspected BHF whose epidemiological and clinical features were similar to those of the first patient. This report describes the first use of intravenous ribavirin therapy for BHF in humans, and the results suggest the need for more extensive clinical studies to assess the usefulness of ribavirin for treating BHF.