Vascular reaction following intramedullary nailing of the tibia in dogs

We have reinvestigated radioiodinated plasminogen as an agent for localizing preformed thrombi. Canine plasminogen was isolated from fresh plasma by the affinity chromatography technique on a lysine-sepharose 4B column and tagged with I-123 or I-131, at less than one iodine atom per molecule of enzyme, by the conventional ICI method. When injected into dogs more than 2 days after thrombus induction, radioiodinated plasminogen produced thrombus-to-blood activity ratios of 7.8 +/- 2.4. Thrombi as old as 6 days can be visualized in 80% of the cases. Both the weight of the thrombus and the thrombus-to-blood ratio are more variable for 1-day-old thrombi; this may be associated with plasminogen release accompanying thrombus retraction. The results suggest that radioiodinated plasminogen has potential as an imaging agent for pre-existing thrombi.     

Effect of a high-beef diet on the fecal bacterial flora of humans

Ten human volunteers completed a 4-month diet series consisting of 1 month each of a control diet, a meatless diet, a high-beef diet, and the same control diet. Fat and fiber contents were essentially the same in all four diets, but protein content was doubled during the high-beef diet. During the 4th week on each diet, three stool specimens collected from each volunteer were analyzed for chemical composition and content of facultative, aerobic, and anaerobic bacteria. The bacteriological data are presented in this paper. High beef protein consumption had little effect on the composition of the intestinal flora. There were no significant differences in total counts of facultative and aerobic or anaerobic organisms in the feces when volunteers were on meatless or high-beef diets. At the species level, when counts during the two control diets were comparable, in only three instances did the change from the meatless to a high-beef diet significantly influence the bacterial numbers. The ratio of mean counts of anaerobic to facultative and aerobic organisms was approximately 15:1 during the meatless diet and 34:1 during the high-meat diet. The data indicate that animal protein consumption has little effect on the fecal bacterial profile in humans.     

A cannabinoid with cardiovascular activity but no overt behavioral effects

Abnormal-delta8-tetrahydrocannabinol (ABN-delta8-THC) failed to elicit central nervous system and cardiovascular effects in laboratory animals. Abnormal-cannabidiol (ABN-CBD) was also devoid of overt behavioral effects but produced marked hypotension with only slight bradycardia in anesthesized dogs.     

Standardization of the chromium-51 release, cell-mediated cytotoxicity assay: cryopreservation of mouse effector and target cells

Utilizing controlled cryopreservation techniques, we were able to standardize the 51Cr release cytotoxicity assay and thereby ensured reliable comparisons between results obtained on different days. Optimal conditions for freezing of both effector and target cells were quite similar. Dimethyl sulfoxide (DMSO) at a concentration of 7.5-10.0% was employed as the cryoprotective agent and cells were frozen at the rate of -1 degrees C/minute. The handling procedures for the cells before and after freezing were important. Factors affecting recovery of functional reactivity were related to toxicity of DMSO for the cells, the osmotic stress placed upon the cells as the DMSO was being removed after thawing, the handling temperature of the freshly thawed cells, and the susceptibility of cells to mechanical damage immediately after thawing. The recovery of lymphocytes after freezing was about 70%; the recovery of cytotoxicity was around 85%. Syngeneic cytotoxic reactivity induced by inoculation with the Moloney strain of murine sarcoma virus was cryopreserved, as were allogeneic cytotoxicity and natural cytotoxic reactivity. Multiple tests employing effector cells from the same frozen pool gave reproducible results; the standard error of the mean percent cytotoxicity was less than 1.5%. Cryopreserved target cells gave decreased day-to-day variability in susceptibility to lysis, since the same population of cells could be employed in each assay. These results demonstrated conclusively that we can now have a constant source of effector cells and target cells, which can be used from assay to assay as an internal standard.