Re-entrant excitation initiated in models of inhomogeneous atrial tissue.

We demonstrate that a shift of the vulnerable window caused by tissue inhomogeneity can play a role in the generation of re-entrant excitation. The Earm-Hilgemann-Noble equations were incorporated into one- and two-dimensional inhomogeneous partial differential equation models of atrial tissue. Inhomogeneity was produced by a reduction of gNa over part of the medium and the vulnerable window for initiating re-entrant activity in homogeneous models determined from numerical integrations. Forty percent reduction of gNa produced little effect on the width of the vulnerable window, but the onset of the vulnerable window was delayed. The delay of the vulnerable window facilitates the initiation of re-entry at junctions between tissue with normal and reduced excitability, even though there is hardly any change in action potential duration.

AIDS-phobia and political reaction in California: student versus public responses to reactive political initiatives.

A "social reactivist" study was conducted of the responses of 563 students enrolled in a Southern California university compared with those of a random sample of 1002 Californians telephone-polled by the California Poll. The study focused on AIDS-phobia, the fear of getting AIDS or the AIDS virus, HIV, from casual contact. In both samples, AIDS-phobia correlated well with reactive political sentiment. Students who were AIDS-phobic were expected to vote in favor of proquarantine initiatives (Proposition 64 in 1986 and Proposition 69 in June 1988). California Poll respondents who were AIDS-phobic, likewise, were expected to vote in favor of Proposition 102 (November 1988) which required reporting HIV-positive patients to local health officers. In the student samples, however, AIDS-phobia was found by factor analysis to have two subsets: AIDS-phobia-Wet and AIDS-phobia-Dry. These did not appear in the California Poll results. In the 1988 student sample, AIDS-phobia-Wet was significant in explaining proquarantine sentiment, while AIDS-phobia-Dry proved significant in explaining sexual activity. The converse was not true. AIDS-phobia is a major characteristic of the social audience to AIDS as a disease and may prove decisive in the evolution of the disease. Support for the victim (or lack of it) may influence the course of the disease and even public funding to fight the disease. AIDS-phobia may also blind heterosexuals to their own vulnerability, thus making them vulnerable to the disease.

Preparation of human hemoglobin Ao for possible use as a blood substitute.

A procedure is presented for the preparation of a purified fraction of adult human hemoglobin (HbAo) from one unit of outdated blood. The entire process requires less than 16 h and gives a sterile, endotoxin-free solution of HbAo (approximately 30 g) in a yield of 50%. The solutions are isoionic with a conductivity of less than 15 mu mhos and less than 2 mmol total phosphorus per mol heme. The methemoglobin content is less than 1% and on storage at 4 degrees C rises less than 1% per month.