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PubMed1956

Reversible collapse of rabbit ears after intravenous papain, and prevention of recovery by cortisone.

A substance has been demonstrated in solutions of crude papain, which, when injected intravenously into 1 kilo rabbits, in amounts less than 5 mg., results in complete collapse of both ears. The phenomenon becomes visible 4 hours after injection, and is complete within 24 hours. 3 or 4 days after papain, the ears gradually reassume their normal form. Ear collapse is associated with depletion of the ear cartilage matrix, and the disappearance of basophilia from the matrix. Similar changes occur in all other cartilage tissues, including bones, joints, larynx, trachea, and bronchi. At the time when the ears are restored to normal shape, the basophilic matrix reappears in cartilage. Repeated injections of papain, over a period of 2 or 3 weeks, bring about immunity to the phenomenon of ear collapse. When the arterial circulation to one ear is occluded for 15 minutes at the time of injection of papain, this ear is protected against collapse. The effect of crude papain could not be reproduced by crystalline papain protease or crystalline papain lysozyme, which together comprise a considerable portion of the dry weight of papain. The nature of the responsible factor has not been determined, and the possibility that chymopapain may be implicated is currently under study. Cortisone prevents the return of papain-collapsed ears to their normal shape and rigidity. Possibly this reflects a capacity of cortisone to impede the synthesis or deposition of sulfated mucopolysaccharides in tissues.

Animals↗

PubMed1958

The removal of cartilage matrix, in vivo, by papain; identification of crystalline papain protease as the cause of the phenomenon.

The intravenous injection of crystalline papain into young rabbits results in depletion of cartilage matrix throughout the body, with loss of rigidity and collapse of the ears, provided the enzyme is inactivated by oxidation or sulfhydryl blocking agents prior to administration. Cysteine-activated crystalline papain, when injected intravenously, produces little or no change in cartilage. The changes which occur in cartilage following an injection of inactivated crystalline papain are indistinguishable from those produced by crude papain. Activation of crude papain by cysteine prior to injection results in loss of its capacity to produce in vivo changes in cartilage. The progressive changes which take place in cartilage in vivo also occur in vitro in isolated rabbit ears removed shortly after an injection of crude papain or inactivated crystalline papain. In vitro ear collapse occurs rapidly at 37 degrees C. and does not occur at 4 degrees C. Collapse is enhanced by exposing the cartilage to cysteine and prevented by exposure to iodoacetamide or p-chloromercuribenzoate. The direct action of crystalline papain on plates of normal cartilage, in vitro, results in the same gross and histological changes which were observed in vivo. The direct action is accelerated by cysteine and inhibited by iodoacetamide or p-chloromercuribenzoate. The intravenous injection of iodoacetamide-treated bromelin produces the same in vivo changes in cartilage as papain. Untreated bromelin has no demonstrable effect on cartilage. It is suggested that the reason for the failure of activated papain to enter cartilage, after being injected intravenously, is that it probably reacts with a substrate or substrates in the blood. Oxidized or otherwise inactivated papain, in contrast, is readily taken up by cartilage and there converted to its active form.

Animals↗

PubMed1958

Papain-induced changes in rabbit cartilage; alterations in the chemical structure of the cartilage matrix.

Some biochemical aspects of the collapse of the rabbit ears produced by the intravenous injection of papain have been studied. A marked depletion of chondromucoprotein (M.C.S.) and a reduction of the S(35) content of cartilage matrix were found to coincide with the gross and histologic changes in the cartilage. At the same time there was a marked increase in the amount of S(35) in the serum and an increase of S(35) and glucuronic acid excreted in the urine. Alteration in the composition of the M.C.S. remaining in the cartilage of the papain-injected animals was detected. The findings indicate that the collapse of the rabbit ears is due to loss of chondromucoprotein from cartilage and reduction of chondroitin sulfate in the chondromucoprotein that remains. All these changes were reversed in recovery.

Animals↗

PubMed1954

Selective necrosis of cardiac and skeletal muscle induced experimentally by means of proteolytic enzyme solutions given intravenously.

Focal necrosis of cardiac and skeletal muscle was produced regularly in rabbits by means of a single intravenous or intra-arterial injection of a solution of crude papain. Similar lesions were produced in rats and mice injected with this material. The intravenous injection of solutions of ficin, trypsin, and streptokinase also resulted in comparable lesions of cardiac and skeletal muscle in rabbits. The lesions in the myocardium became apparent within 6 hours after injection of the enzyme; they consisted essentially of focal degeneration and necrosis of the sarcoplasm and myofibrils within a segment of muscle fiber. An inflammatory reaction consisting of a small number of polymorphonuclear leukocytes and considerable numbers of mononuclear cells, and often multi-nucleated giant cells, was present within the lesions. In some instances severely damaged fibers were replaced by fibrous tissue and in others proliferation of muscle cell nuclei and restitution of the fiber appeared to take place. Similar changes of a lesser degree were also observed in skeletal muscle. The findings are discussed in connection with the pathogenesis of the anatomical lesions of rheumatic fever, periarteritis nodosa, and other hypersensitivity states.

Animals↗

PubMed1955

The interactions of the non-specific inhibitor of hyaluronidase with hyaluronidase and proteolytic enzymes in vivo.

1. Following intravenous administration of testes hyaluronidase in rabbits and dogs, there is a decrease in the level of the non-specific inhibitor of hyaluronidase in serum. 2. If a large amount of hyaluronidase is injected, the inhibitor level is reduced to zero and hyaluronidase may be present in serum for some time after the injection. The hyaluronidase activity of such samples of serum increases when the serum is incubated with papain. 3. Hyaluronidase activity is found in the livers of the injected animals in large amounts and this activity is increased considerably when the homogenate of this tissue is incubated with papain. 4. Intravenous administration of several proteases or venom produces a decrease in the serum inhibitor level. Intravenous administration of streptokinase produces such a decrease in rabbits but not in dogs. 5. There is a correlation between the depletion of the inhibitor from the serum and the occurrence of a slow, persistent depression of blood pressure upon administration of proteolytic enzymes.

Animals↗

PubMed1958

The action of enzymes on rhodopsin.

The effects have been examined of chymotrypsin, pepsin, trypsin, and pancreatic lipase on cattle rhodopsin in digitonin solution. The digestion of rhodopsin by chymotrypsin was measured by the hydrolysis of peptide bonds (formol titration), changes in pH, and bleaching. The digestion proceeds in two stages: an initial rapid hydrolysis which exposes about 30 amino groups per molecule, without bleaching; superimposed on a slower hydrolysis which exposes about 50 additional amino groups, with proportionate bleaching. The chymotryptic action begins at pH about 6.0 and increases logarithmically in rate to pH 9.2. Trypsin and pepsin also bleach rhodopsin in solution. A preparation of pancreatic lipase bleached it slightly, but no more than could be explained by contamination with proteases. In digitonin solution each rhodopsin molecule is associated in a micelle with about 200 molecules of digitonin; yet the latter do not appear to hinder enzyme action. It is suggested that the digitonin sheath is sufficiently fluid to be penetrated on collision with an enzyme molecule; and that once together the enzyme and substrate are held together by intermolecular attractive forces, and by the "cage effect" of bombardment by surrounding solvent molecules. The two stages of chymotryptic digestion of rhodopsin may correspond to an initial rapid fragmentation, such as has been observed with many proteinases and substrates; superimposed upon a slower digestion of the fragments. Since the first phase involves no bleaching, this may mean that rhodopsin can be broken into considerably smaller fragments without loss of optical properties.

Animals↗

PubMed1954