T. Lloyd Fletcher

Stability of Pepsin During Storage in Canine Gastric Secretions and in Aqueous Solutions

SummaryWe have determined the pepsin activity of canine gastric secretions (CGS) and of commercial crystalline porcine pepsin (CCPP) solutions at pH 1.8 (5 and 10 μg/ml) for various periods of time, at room temperature (23-28°), at refrigerator temperature (4°), in the freezing compartment of a refrigerator (—4°) and at —20°. Lowered activity was found under most of these conditions. The lower the temperature and the longer the time the greater is the loss. The CGS samples deviated somewhat from this general trend by showing some increases as well as decreases in activity at all temperatures except at 0°. We, therefore, recommend holding such samples in an ice bath at 0° for not longer than 3 hr, or addition of acidified glycerol for storage up to 1 day at —20°. Fresh preparations of CCPP solutions retained activity in an ice bath for up to 5 hr. If it is necessary to store CCPP solutions for a longer period of time—up to 6 days—addition of albumin or a combination of albumin and acidified glycerol is ess...Summary We have determined the pepsin activity of canine gastric secretions (CGS) and of commercial crystalline porcine pepsin (CCPP) solutions at pH 1.8 (5 and 10 μg/ml) for various periods of time, at room temperature (23-28°), at refrigerator temperature (4°), in the freezing compartment of a refrigerator (—4°) and at —20°. Lowered activity was found under most of these conditions. The lower the temperature and the longer the time the greater is the loss. The CGS samples deviated somewhat from this general trend by showing some increases as well as decreases in activity at all temperatures except at 0°. We, therefore, recommend holding such samples in an ice bath at 0° for not longer than 3 hr, or addition of acidified glycerol for storage up to 1 day at —20°. Fresh preparations of CCPP solutions retained activity in an ice bath for up to 5 hr. If it is necessary to store CCPP solutions for a longer period of time—up to 6 days—addition of albumin or a combination of albumin and acidified glycerol is essential.

Experimental Vascular Grafts

1 National Heart Institute Trainee. 2 Postdoctorate Research Fellow, U. S. Public Health Service. 3 Instructor, Department of Surgery, and Fellow, American Cancer Society. 4 Instructor in Surgery. 5 Damon Runyon Cancer Fellow, Department of Surgery, University of Washington School of Medicine, 1950-1952; at present, Captain, M.C., U. S. Army Medical School, Washington, D. C. 6 Formerly Instructor in Surgery; at present in private practice, Wilmington, N. C. 7 Research Chemist and Head of the Surgical Chemistry Laboratory. 8 Associate Professor of Surgery, University of Washington School of Medicine. 9 Professor of Surgery and Executive Officer of Department of Surgery, University of Washington School of Medicine. From the Department of Surgery, University of Washington School of Medicine, Seattle, Washington. This was aided in part by a grant from the Division of Research Grants and Fellowships, National Heart Institute, Bethesda, Maryland, (H-1136), by a Grant from Initiative 171 funds of the State of Washington, and the Vadheim Surgical Research Fund of the Department of Surgery. This report represents a further study of the problems proposed in a previous communication, by Kanar et al. (1), who compared five fresh autogenous vein grafts implanted into the thoracic aortas of growing pigs with five similar grafts surrounded by crystalline dicetyl phosphate. Their conclusions were that: 1. Ve-

Fibrosing properties, in the rat, of compounds related to dicetyl (di-n-hexadecyl) phosphate —I

Abstract In this preliminary survey, twenty-six compounds, related in one way or another to dicetyl(di- n -hexadecyl)phosphate, were compared with this substance as to tissue fibrosing activity by subcutaneous injections in the rat. Only dialkylphosphates (and the single alkylborate used) with a chain length of sixteen or eighteen carbon atoms were active. The only substance with unsaturated alkyl chains, dioleyl(C 18 )phosphate, was inactive. Dicholesteryl-phosphate and phosphite were not active. None of the phosphites (di- or tri-) was active. Dicetylborate produced less flbrosis than the phosphate and this was accompanied by marked eosinophilia and subsequent encapsulated necrosis. Dioctadecyl phosphate was indistinguishable in these experiments from dicetyl phosphate.

Decreased gastric secretory activity following injection of lignin sulfonates.

Summary Solutions of calcium lignin sulfonates injected immediately after ligation in the Shay rat (20 mg/100 g rat weight) afforded pronounced protection against ulceration as compared with controls. The same material given per osalso protected Shay rats against ulceration, probably by a different mechanism.

Effect of 4-bromo-3-hydroxybenzyloxyamine (Brocresine) on gastric secretion in pouch dogs.

Summary We studied the effect of Brocresine on the gastric secretory response of denervated and innervated pouch dogs. Brocresine is a potent inhibitor of histidine decarboxylase. It has been shown that in the rat (2, 3) and perhaps in the human (4), this drug inhibits gastric secretory response to administration of exogenous gastrin, but not of exogenous histamine. In the present work we found that responses to exogenous gastrin, or gastrin-like synthetic pentapep-tide, or histamine, are not significantly altered by administration of Brocresine in either acute experiments, or over a period of several months of chronic dosage. The responses to feeding in a group of Brocresine-treated innervated pouch dogs were also not significantly altered over a period of several weeks. The results suggest that in the dog histamine may not be the final mediator of all gastric stimulation. This hypothesis is also supported by the fact shown (but not newly-discovered here) that the ratio of maximal response with gastrin to maximal response to histamine varies widely from 1 pouch dog to another. Response of the pouch to gastrin stimulation appears to be much more subject to differences (perhaps subtle) in surgical technique than response to histamine stimulation.

Synthesis and reactions of 2,2′-hydrazofluorene and related compounds

Methods are described for synthesis of the hitherto unknown 2,2′-hydrazofluorene, and 2,2′-azofluorene, compounds of possible importance in elucidation of carcinogenic mechanisms.

The primate as an experimental animal suitable for measuring gastrin-stimulated gastric acid secretion

SummaryA study of the alteration of secretory patterns through the use of Heidenhain pouches in twoMacaca nemestrina, following subcutaneous injection of a gastrin preparation, revealed that the response was more reliable when the dorsal trunk, rather than the anterior thigh, was utilized as the site of injection. A plateau of maximal secretory response was obtained when 18–25 mg. of the extract per kilogram of body weight was injected.Although the observations were not conclusive, they suggested that pepsin is liberated by a “washing-out” process but is also continuously secreted in response to continued stimulation with gastrin extract.Evaluation of the monkeys response to stimulation by gastrin extracts established that theMacaca nemestrina is a different type of experimental animal when compared to the dog. The dog shows a response of gastric secretion to much smaller amounts of the gastrin extract and is less sensitive to other stimuli of an external nature.