Fluorescent quantitation of epinephrine and norepinephrine in plasma of patients suspected of having pheochromocytomas is of considerable diagnostic value. The concentrations of these pressor amines in normal subjects, patients with various diseases with and without hypertension, and 13 patients with pheochromocytomas are reported. In all patients with pheochromocytomas and sustained hypertension the concentrations of pressor amines were significantly elevated. However, in patients with paroxysmal hypertension secondary to pheochromocytomas the pressor amine concentrations may be unelevated when the blood pressures are normal. In this latter group provocative tests with intravenous histamine are indicated to induce hypertension prior to quantitating pressor amines.
Application of High Speed Flash Tube to Photographing the Fundus of the Eye in Color
A high speed flash tube is adapted to the Nordensen retinal camera, so that the fundus of the human eye can be photographed in color. The high speed flash eliminates the usually deleterious effect of blinking and eye movements. Special electronic circuits are needed to provide a flickering light from the same flash tube to enable the operator to adjust and focus the camera. Ektachrome film is used and this is over-developed to gain equivalent exposure. For the fundus photographs this apparently results in no loss of color relationships.