Role of immune interferon in the monocytic differentiation of human promyelocytic cell lines induced by leukocyte conditioned medium

Conditioned medium (CM) from lectin-stimulated human leukocytes contains factors that induce human promyelocytic cell lines to differentiate along the monocytic pathway. In this report, we show that human promyelocytic cell lines are also induced to differentiate along this pathway by immune interferon (IFN gamma). Various preparations of IFN alpha tested did not induce this differentiation. In cultures containing IFN gamma, the cells are induced to coordinately express monocyte markers and functions such as monocyte-specific surface antigens, HLA-DR antigens, nonspecific esterase, receptors for the Fc fragment of IgG, and the ability to mediate antibody-dependent cell- mediated cytotoxicity. Our data indicate that differentiation induced by IFN gamma is not secondary to an arrest of growth of promyelocytic cell lines, but rather that a proportion of cells is induced along a programmed pathway of terminal differentiation similar to that of normal monocytes. CM contains IFN gamma, but its ability to induce differentiation is greater than expected on the basis of its content of IFN gamma. Treatments at 56 degrees C or at pH 2.0, which abolish IFN gamma activity, abrogate the differentiation ability of CM. The antiviral activity and the differentiation activity contained in the CM are coeluted from gel filtration and reverse-phase columns. Monoclonal antibodies anti-IFN gamma, which completely abrogate the differentiation ability of IFN gamma and the antiviral activity in the CM, completely suppress the induction of some monocyte markers by CM, but only reduce the expression of others. When IFN gamma is added to CM, promyelocytic cell lines are induced to differentiate to a much greater extent than that induced by either IFN gamma or IFN gamma- depleted CM alone. These results show that the differentiation activity of leukocyte CM is due to the synergistic effect of IFN gamma and other factors not yet identified.     

Predictors of the use of dental services by older veterans

By the year 2000, it is likely that more than 66% of all US males will be veterans as a result of the large World War II cohort. This growing population of older veterans will have a major influence on the use of dental services at Veterans Administration facilities. The objectives of the project reported here were to identify and examine factors that explain use of dental services by noninstitutionalized veterans older than 55 years; this was a secondary analysis of a VA commissioned survey of 3,013 community-based veterans older than 55 years.
A behavioral model developed by Anderson and Aday that identified predisposing, enabling, and need factors that determined use of health care services was adopted to analyze the data. A linear regression analysis showed that need factors accounted for the greatest degree of explained variance in use of dental services (R²= .15), whereas enabling factors accounted for the least degree of variance (R²= .02). Perception of dental problems, positive perception of physical health, perception of ability to meet expenses, and levels of education and income were significant predictors of use of dental services.
The findings of this study show the use of dental services by noninstitutionalized veterans and other noninstitutionalized older populations is influenced by similar factors. The findings can be useful in discussing and formulating dental health care policy for older veterans.     

The hemostatic defect of uremia. I. Clinical investigation of three patients with acute post-traumatic renal insufficiency

The abnormalities of the hemostatic mechanism in three consecutive patientswith acute renal insufficiency have been studied. In every case a prolongedclotting time in silicone and a prolonged bleeding time were found. In twocases defective prothrombin consumption was also present. Coagulation studiesrevealed no significant deficiency of plasma factors, no serious deficiency ofplatelet numbers or function and no well-defined anticoagulant effect to explain the changes. All three cases developed significant clinical bleeding at sometime during the course of the renal insufficiency.

Submitted on April 3, 1956 Accepted on June 2, 1956