Hindlimb hypokinesia was induced in rats by the Morey method to characterize the response of the soleus muscle. Rats suspended for 1-4 wk exhibited continuous and significant declines in soleus mass, function, and contractile duration. Soleus speeding was in part explained by an alteration in fiber type. The normal incidence of 70-90% type I fibers in the soleus muscle was reduced after 4 wk of suspension to 50% or less in 9 of 11 rats. A significant decline in type I myosin isozyme content occurred without a change in that of type II. Other observed histochemical changes were characteristic of denervation. Consistent with soleus atrophy, there was a significant increase in lysosomal (acid) protease activity. One week of recovery after a 2-wk suspension was characterized by a return to values not significantly different from control for muscle wet weights, peak contraction force, one-half relaxation time, and type I myosin. Persistent differences from control were observed in maximal rate of tension development, contraction time, and denervation-like changes.

Alzheimer's disease (AD) is known to be associated with loss of cholinergic neurons in the nucleus basalis of Meynert, located in the posterior basal forebrain. Structural changes of septal nuclei, located in the anterior basal forebrain, have not been well studied in AD. Using a validated algorithm, we manually traced septal nuclei on high-resolution coronal magnetic resonance imaging (MRI) in 40 subjects with mild cognitive impairment (MCI) or AD, 89 healthy controls, and 18 subjects who were cognitively normal at the time of MRI but went on to develop AD an average of 2.8 years later. We found that cognitively normal subjects destined to develop AD in the future had enlarged septal nuclei as compared to both healthy controls and patients with current MCI or AD. To our knowledge, this is the first time a brain structure has been found to be enlarged in association with risk of AD. Further research is needed to determine if septal enlargement reflects neuroplastic compensation, amyloid deposition, inflammation, or another process and to determine whether it can serve as an early MRI biomarker of AD.

Cranial solitary plasmacytomas are uncommon lesions, and localization to the skull base is rare. Here we present a case in a 36-year-old woman who complained of dizziness and mild headaches. Radiographic imaging indicated the presence of a solitary skull base lesion in the posterior cranial fossa. Laboratory tests and imaging excluded systemic disease. A biopsy of the lesion confirmed the diagnosis of plasmacytoma. The patient was treated with proton-beam radiation and had a complete clinical and radiographic resolution, demonstrating the previously unreported utility of monotherapy with proton-beam radiation in such cases.