Autogenous veins are the ideal substitute for bridging venous defects. Experimentally, fresh homografts have patency rates comparable to autografts. However, a method of preservation must be employed if homografts become practical for clinical use. In this study, homografts were frozen, irradiated, and stored for a total of 6 weeks. Following femoral venous reconstruction, patency rates between frozen, irradiated homografts and fresh autografts were compared and found to be similar over a 6 month period. Recanalization of the frozen, irradiated homografts occurred at the same rate as did that of the autografts. This study concludes that cryopreservation and irradiation are suitable methods of preservation that do not adversely affect patency. In addition irradiation will sterilize tissue and may decrease the potential of the graft to stimulate the recipient's immunologic system.

Indium-111 chloride was administered intravenously for the scintigraphic demonstration of experimental abdominal wall abscesses in rabbits. Scintiscans performed 24 hr after injection of the isotope demonstrated reproducible localization of the abscesses. The abscess wall and kidneys contained maximal levels of the isotope with lesser amounts in the spleen, liver, lung, and colon. Indium-111 chloride may have clinical application for the scintigraphic identification of inflammatory masses.

Microaggregates of platelets have been found in stored blood and in extracorporeal circulation systems and the potential microembolism of these particles intensely studied. Four currently available filters were studied for their filtration effectiveness of induced platelet microaggregates and for the removal of normal platelets from blood collected in acid citrate dextrose or heparin. Dacron wool filtration significantly (P less than 0.001) reduced aggregates in 13 to 80 mu sizes to a level similar to that in normal blood. In general, as filtration effectiveness increased so did the elimination of normal platelets.

Effects of circulating adrenergic amines on the cerebral circulation remain contraversial. Common carotid (CCF) and internal carotid (ICF) arterial flows were determined electromagnetically in eight lightly anesthetized baboons to evaluate alterations in the cephalic and cerebral vascular beds, respectively. Epinephrine (E), norepinephrine (NE), phenylephrine (PE), and isoproterenol (I) were injected randomly in doses of 10-3, 10-2, 10-1, and 1 mug (base) per kilogram into each carotid artery. Measurements were repeated in four animals after alpha-adrenergic blockade with phenoxybenzamine and in another four animals after beta-adrenergic blockade with propranolol. Baseline CCF was 75 plus or minus 10 (S.E.M.) ml. per minute and ICF was 58 plus or minus 8 ml. per minute. Significant (p smaller than 0.05) CCF changes without arterial pressure alterations occurred with 10-1 mug per kilogram doses. Alpha blockade significantly (p smaller than 0.05) attenuated the effects of E, NE, and PE on CCF while beta blockade significantly (p smaller than 0.05) attenuated the effect of I on CCF. ICF did not change significantly (p greater than 0.05) after injection of any of the vasoactive amines, unless associated with pressure changes at the highest dose. Our data suggest the presence of alpha- and beta-adrenergic receptor sites within the cephalic circulation resulting in significant flow responses to intra-arterial adrenergic amines. The absence of responses in the cerebral circulation suggests that circulating catecholamines do not significantly influence or regulate the cerebral vasculature. In addition the data suggest that use of adrenergic agonists to alter the hemodynamics of the cerebral circulation is limited.