Tissue NAGLU enzyme activity in treated and untreated mice. (a) Brain, (b) liver, (c) spleen, and (d) heart from 4 to 6 animals in each group were homogenized and N-acetyl-glucosaminidase activity was determined. Activity values ± SEM for each MPS IIIB group are graphed relative to the mean of the normal untreated group. Significant differences of treated from untreated MPS IIIB groups are indicated with *P < 0.05 and **P < 0.01. AAV, adeno-associated virus; BMT, bone marrow transplant; NAGLU, N-acetyl-glucosaminidase.