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In an attempt to determine the metabolic defect causing severe combined immunodeficiency (SCID) in horses in which altered purine metabolism has been observed, various parameters of purine and pyrimidine metabolism were evaluated. The activities of nine purine enzymes (adenosine kinase, purine nucleoside phosphorylase, deoxyadenosine kinase, deoxycytidine kinase, 5'-nucleotidase, AMP deaminase, hypoxanthine-guanine phosphoribosyl transferase, and adenine phosphoribosyl transferase were measured in fibroblasts. All activities determined for SCID horses were normal. Uptake of 10 microM adenosine or 2'-deoxyadenosine (a growth inhibitory concentration for SCID fibroblasts) by SCID fibroblasts was identical to that found for normal fibroblasts in the presence of both 1 and 50 microM phosphate. The Km determined for the transport of both adenosine and 2'-deoxyadenosine was 35 microM. In the presence of p-nitrobenzylthioguanosine (a nucleoside transport inhibitor), 2'-deoxyadenosine uptake was inhibited to the same extent in all fibroblast lines tested. To determine if the last step in pyrimidine biosynthesis might be altered in SCID fibroblasts, UMP synthase activities were evaluated but found to be normal (0.5 nmol UMP formed/min/mg protein).
N S Magnuson, and
L E Perryman, and
D P Suttle, and
J L Robinson, and
P H Mason, and
K M Marta
July 2014,
Animal cognition,
N S Magnuson, and
L E Perryman, and
D P Suttle, and
J L Robinson, and
P H Mason, and
K M Marta
July 2008,
Behavioural processes,
N S Magnuson, and
L E Perryman, and
D P Suttle, and
J L Robinson, and
P H Mason, and
K M Marta
May 2013,
Animal cognition,
N S Magnuson, and
L E Perryman, and
D P Suttle, and
J L Robinson, and
P H Mason, and
K M Marta
May 2008,
Behavioural processes,
N S Magnuson, and
L E Perryman, and
D P Suttle, and
J L Robinson, and
P H Mason, and
K M Marta
January 2020,
Animal cognition,
N S Magnuson, and
L E Perryman, and
D P Suttle, and
J L Robinson, and
P H Mason, and
K M Marta
January 2019,
Animal cognition,
N S Magnuson, and
L E Perryman, and
D P Suttle, and
J L Robinson, and
P H Mason, and
K M Marta
July 2008,
Animal cognition,
N S Magnuson, and
L E Perryman, and
D P Suttle, and
J L Robinson, and
P H Mason, and
K M Marta
September 2016,
Animal cognition,
N S Magnuson, and
L E Perryman, and
D P Suttle, and
J L Robinson, and
P H Mason, and
K M Marta
August 2008,
Behavioural brain research,
N S Magnuson, and
L E Perryman, and
D P Suttle, and
J L Robinson, and
P H Mason, and
K M Marta
January 2009,
Proceedings of the National Academy of Sciences of the United States of America,
