With Lew Ayres stigmatized by his conscietious objector status during WW II and unable to continue as Dr. Kildare in the still-popular series, MGM bosses let Lionel Barrymore continue as the wizened Dr. Gillespie and here gave him a trio of new assistants. His new aides were Johnson from Kansas, Luke, an Asian-American from Brooklyn, and Quine from Australia. The path of the series turns to lighter comedy with this varied bunch as they concentrate on amnesia victim Peters. (http://movies.tvguide.com/dr-gillespies-new-assistant/113123)

"The Story of Dr. Kildare Radio Program
Paramount Pictures first brought Max Brand's character, Dr. James 'Jimmy' Kildare to the big screen with their 1937 crime feature, Internes Can't Take Money starring Barbara Stanwyck and featuring Joel McCrea as young intern, Jimmy Kildare. Notably absent in the Paramount feature is the character, Dr. Leonard Gillespie. Metro-Goldwyn-Mayer coaxed author Max Brand and his characters into its stable in 1938, launching a highly popular series of fifteen films featuring either/both young Dr. Kildare or Dr. Leonard Gillespie:

1938 Young Dr. Kildare
1939 Calling Dr. Kildare
1939 The Secret of Dr. Kildare
1940 Dr. Kildare's Strange Case
1940 Dr. Kildare Goes Home
1940 Dr. Kildare's Crisis
1941 The People vs. Dr. Kildare
1941 Dr. Kildare's Wedding Day
1942 Dr. Kildare's Victory
1942 Calling Dr. Gillespie
1942 Dr. Gillespie's New Assistant
1943 Dr. Gillespie's Criminal Case
1944 3 Men in White
1945 Between Two Women
1947 Dark Delusion

The first nine of the M-G-M features starred Lew Ayres as Dr. James Kildare and Lionel Barrymore as Dr. Leonard Gillespie. 1942's Calling Dr. Gillespie was the first of the M-G-M features of the series to un-tether Dr. Gillespie from young Dr. Kildare. Following Dr. Gillespie's solo outing, M-G-M tethered Dr. Gillespie to Van Johnson as Dr. Randall 'Red' Adams, in Dr. Gillespie's New Assistant (1942). The Lionel Barrymore - Van Johnson duo continued for three more features: Dr. Gillespie's Criminal Case, 3 Men In White, and Between Two Women. The series concluded with 1947's solo outing of Dr. Gillespie in Dark Delusion, the only one of the fifteen Dr. Gillespie-related features not to carry Max Brand as credited with the characters and story.

Far and away the most popular combination of the Max Brand characters were Dr. Gillespie and his young protege, Dr. James Kildare. The Lionel Barrymore and Lew Ayres combination--and chemistry--served as the basis for all of the Dr. Kildare feature films, Radio productions and Television productions that followed between 1938 and 1973.
M-G-M Takes Young Dr. Kildare to the Air."

mehr: http://www.digitaldeliftp.com/DigitalDeliToo/dd2jb-Dr-Kildare.html