Definition is a rhetorical mode that can be used in something smaller or shorter than a full paper. You can use extended definition for several paragraphs only in a paper of much greater length. You also can add to a paper a one-paragraph definition--like a brief encyclopedia definition.
Immunodeficiency: Therapies include thymus transplantation and adoptive transfer of mature T cells (ATMTC) for individuals with complete DiGeorge syndrome and appropriate prophylaxis measures and monitoring autoimmune complications for incomplete or partial DiGeorge syndrome.
However, the relationship between digoxin toxicity and the serum digoxin level is complex. Clinical toxicity results from the interactions between digitalis, various electrolyte abnormalities, and their combined effect on the sodium-potassium adenosine triphosphatase (Na+/K+ ATP ase) pump. Infants and children taking digoxin tolerate higher doses and plasma levels.