Papain induced changes in cartilage.

I n tr o d u c tio n T E cfi'ccls o f the systemic adminis­ tration o f crude papain to young rabbits were first described by Thomas (1956), who noted that the most obvious change was a bilateral collapse o f the ears. This effect was lost within a few days. Subsequently llu lth and Westerborn (1959) and Merkow and Lalieh (1961), who iLsecl crude papain in single and repeated (loses, and in different species o f animals, not only confirmed but also elaborated on the effects o f its administration. After finding that crystalline papain failed to produce collapse o f rabbit ears, even when injected in large amounts, McClusky and Thomas (1955!) observed that i f this enzyme preparation was in­ activated before administration by the addition o f a thiol-combining agent such as iodo-acctamide, the typical collaji.se did occur. Th e inactivated enzyme, how­ ever, did not produce this effect in vitro. This study was undertaken to deter­ mine the effects o f local and systemic in­ jections o f inactivated crystalline papain in rabbits and rats, with a view to its possible clinical application in the early treatment o f bilateral cleft palates.