ALTERATION OF BLOOD DURING ACUTE HYPOTENSION: EFFECT OF CONTINUOUS GLASS WOOL FILTRATION

Acute hypotension was produced in heparinized and nonheparinized dogs by hemorrhage and by injections of histamine, and adhesiveness and aggregation of blood elements determined periodically by the screen filtration pressure method. This method measures the pressure required to force blood at a constant rate through a standardized screen with multiple square holes each 20 x 20 micra. In some cases the arterial blood was perfused through a glass wool filter in an extracorporeal system both before and during periods of hypotension. The results of these studies justify the following conclusions:

1. Increased adhesiveness and aggregation of platelets and other blood elements which occur during hypotension produced by hemorrhage or intravenous injections of histamine were indicated by an increase in the screen filtration pressure of blood. These changes were not prevented from developing, or significantly altered by heparinization of the animal.

2. The amount of blood which could be obtained during arterial hemorrhage was significantly increased by heparinization of the animal.

3. The adhesive and aggregated platelets and leucocytes, which formed during hypotension, were removed from the blood when it was perfused through a column of glass wool. This treatment was attended by a decrease in the screen filtration pressure of the blood to or below normal.

4. The increase in screen filtration pressure which occurred during hypotension was much less marked if the animals' blood had first been circulated through pyrex glass wool.

5. Filtration of blood through pyrex glass wool was also attended by a progressive decrease in the mean arterial blood pressure of the animal.

FACTORS IN THE MEMBRANE FILTRATION OF ENTEROVIRUSES

The filtration of two species of enteroviruses through membranes of porosity ranging from 50 to 220 mmu was studied. It was shown that extensive or total losses of virus may attend filtration at these porosities, apparently owing to adsorption of the virus to the membrane matrix. This could be minimized by the incorporation of serum into the virus suspension at the time of filtration, or by pretreating the membrane with serum or with a gelatin solution. It was also found that the first few drops of filtrate, even under optimal conditions, were likely to be virus-free, so that the filtration of too small a volume of virus suspension would result in a relatively great loss of titer. The degree to which these factors were critical was found to decrease with increasing pore diameter.

STUDIES ON THE BIOLOGICAL STABILIZATION OF THIN STILLAGE. I. AEROBIC FERMENTATION

Thin stillage was subjected to aerobic fermentation in both batch and semi-continuous studies, involving forced aeration, sedimentation, and recirculation through a modified trickling filter. The authors have demonstrated that the total solids content and chemical oxygen demand of thin stillage can be reduced considerably by the use of these combined techniques.

OXYGEN-HEMOGLOBIN SYSTEM: A MODEL FOR FACILITATED MEMBRANOUS TRANSPORT

Enhanced transport of oxygen in a Millipore filter containing a solution of hemoglobin can be accounted for by the diffusion of free oxygen as well as of hemoglobin-bound oxygen. A model shows that, at oxygen tensions at which the hemoglobin is fully saturated in a portion of the membrane, the enhanced transport is due to a steeper gradient for free oxygen, whereas in the rest of the membrane an "(oxy)hemoglobin shuttle" operates. A similar model may be useful for explaining facilitated diffusion in other systems.