Heterotopic pregnancy: report of four cases.

Four patients with heterotopic (combined) pregnancies were treated at one institution during the period of a year. The use of fertility agents, infertility surgery, and pelvic inflammatory disease may be risk factors predisposing to an increasing incidence of such pregnancies. Combined pregnancy may reasonably belong in the differential diagnosis in certain clinical settings.

Degradation of poliovirus by adsorption on inorganic surfaces.

Alteration of the specific infectivity of 3H-labeled ribonucleic acid and 14C-protein labeled poliovirus type 1 by adsorption on inorganic surfaces is investigated by application of kinetic theory to data obtained from sequential extractions of adsorbed virus. Some surfaces, e.g.