Action versus animal naming fluency in subcortical dementia, frontal dementias, and Alzheimer's disease.

Accumulating evidence indicates action naming may rely more on frontal-subcortical circuits, and noun naming may rely more on temporal cortex. Therefore, noun versus action fluency might distinguish frontal and subcortical dementias from cortical dementias primarily affecting temporal and/or parietal cortex such as Alzheimer's disease (AD). We hypothesized patients with subcortical dementia, e.g., normal pressure hydrocephalus (NPH) and patients with dementias predominantly affecting frontal cortex, e.g., behavioral variant frontotemporal dementia (bv-FTD) and progressive nonfluent aphasia (PNFA) have more difficulty on action fluency versus noun fluency (e.g., animal naming). Patients with AD, who have temporo parietal cortical dysfunction, should have more difficulty on noun versus verb fluency. A total of 234 participants, including healthy controls (n = 20) and patients diagnosed with NPH (n =144), AD (n = 33), bv-FTD (n = 22) or PNFA (n =15) were administered animal fluency, action fluency, and letter fluency tasks, and the Mini-Mental State Examination (MMSE, to control for dementia severity). NPH and bv-FTD/PNFA patients had significantly higher MMSE scores and animal fluency than AD patients (after adjusting for age), but their action fluency tended to be lower than in AD. Only NPH and bvFTD/PNFA patients showed significantly lower action verb than animal fluency. Results provide novel evidence that action naming relies more on frontal-subcortical circuits while noun naming relies more on temporoparietal cortex, indicating action verb fluency may be more sensitive than noun fluency, particularly for detecting frontal-subcortical dysfunction.

Thyroxine inner ring monodeiodinating activity in fetal tissues of the rat.

We studied thyroxine (T4) inner ring monodeiodinating activity (5-MA) in various tissues of fetal, maternal, and adult male rats. Tissue homogenates were incubated with 0.26 microM T4 in 0.1 M phosphate buffer (pH 7.4) containing 10 mM EDTA and 400 mM dithiothreitol (final volume 0.7 ml) for 10 min at 37 degrees C; the 3,3',5'-triiodothyronine (rT3) generated was measured by radioimmunoassay of ethanol extracts of incubation mixture and the result was corrected for rT3 degradation during incubation. Compared to maternal tissues, T4 to rT3 5-MA in the 14-day-old fetus was increased about 70 times in skeletal muscle (mean +/- SEM, velocity, 5.4 +/- 0.9 versus 0.08 +/- 0.01, pmol rT3/h/mg protein); approximately 8 times in intestine (0.72 +/- 0.17 versus 0.09 +/- 0.03);and approximately 4 times in cerebral cortex (19 +/- 0.5 versus 4.5 +/- 0.9), while it was similar in skin (3.2 +/- 0.48 versus 2.6 +/- 0.52). Hepatic T4 5-MA approximated 1.1 +/- 0.63 in the 14-day-old fetus; it could not be measured reliably in maternal or 19-day fetal tissue because of extensive (greater than 90%) degradation of rT3 during incubation. Relative to mother, T4 5-MA in 19-day fetal tissues was increased approximately 30-fold intestine, approximately 20-fold in skeletal muscle, and approximately 6-fold in cerebral cortex while it was similar in skin. The T4 5-MA in maternal rat tissues did not differ significantly from corresponding values in adult male rat, except skin, where it was lower in the mother rat (2.6 +/- 0.52 versus 4.6 +/- 0.61, p less than 0.05). In summary, relative to adult tissues T4 5-MA is exceedingly active in several fetal tissues, most notably in skeletal muscle followed by intestine and cerebral cortex.