THE JOHNS HOPKINS UNIVERSITY 
SCHOOL. OF MEDICINE 
72S NORTH WOLFE STREET 
BALTIMORE . MARYLAND 21205 
DEPARTMENT OF BIOPHYSICS 
December 13, 1979 
Dr. Donald Fredrickson 
Director, National Institutes 
of Health 
Bethesda, Maryland 20205 
Dear Dr. Fredrickson: 
We would like to express our agreement with the proposed 
revised guidelines for containment requirements in DNA 
recombinant experiments involving col i host-vector systems, 
as outlined in section 1 1 1 -0 , page 69218, Federal Register, 
Vol . 44, No. 232, November 30, 1979. Based on our experience 
with microorganisms such as E. coli , Salmonella thyphimurium 
and others, we consider the containment requirements very 
adequate to minimize or eliminate possible risks arising 
from recombinant DNA molecules. 
Yours respectfully. 
Viviana Amzel , Ph.D 
[ 471 ] 
