Never heard of Caprotti before (August 2012), but his name was mentioned by my Italian Agent Andrea Ridolfi when I informed him about the Dabeg 221 TQ locomotive Steam Engine.
When searching his patents (31 hits) I found two Russian publications.
Added May 2013 on Espacenet: http://nl.espacenet.com:
SU11205 (A1) published 1929-09-30 and
SU35701 (A1) published 1934-03-31
Both patented Caprotti Systems with the IPC desmocode: F01L1/30.
There are various video’s on Youtube from (a model of) the Caprotti system.
There is a working model as an artefact in the collection of the museum Fermodellistico G. Capelletti in citta di Castello Italy.
But the Caprotti system does not look desmodromic to me. The cams operate rockers without a fixed rocker – valve attachment.
The closing “rocker” is some kind of blade spring. Although it has received the IPC-desmocode, it does not seem to be a desmo!