Objective: To determine the utility of detecting a-synuclein (aSyn) in colonic mucosal biopsy tissue as a potential diagnostic biomarker for Parkinson disease (PD). Methods:We used the paraffin-embedded tissue (PET) blot, which degrades physiologic nonaggregated aSyn using proteinase K and enhances antigen retrieval allowing sensitive and selective detection of remaining protein aggregates, to detect aSyn in colonic mucosal biopsies from 15 patients with early PD (,3 years), 7 patients with later PD (.5 years), and 11 individuals without PD. aSyn and serine 129-phosphorylated aSyn (Ser129p-aSyn) were assessed by PET blot and conventional immunohistochemistry.Results: PET blot-resistant aggregated aSyn and Ser129p-aSyn was present in 12 of 15 individuals with early PD, 7 of 7 individuals with later PD, and 11 of 11 control subjects. The number of biopsies positive by PET blot relative to conventional immunohistochemistry was significantly lower in both PD groups compared with the control group for both aSyn and Ser129p-aSyn, whereas routine immunohistochemistry was positive more often in PD, but was positive in as many as 9 of 11 control individuals.Conclusion: Strong evidence of the presence of aggregated hyperphosphorylated aSyn in individuals with and without PD, using such a sensitive and specific method as the PET blot, suggests that colonic deposition of aSyn is not a useful diagnostic test for PD. The utility of detecting aSyn in the colon as a biomarker in combination with other assessments remains to be determined. An accurate diagnostic test for early or prodromal Parkinson disease (PD) is a significant unmet need. Studies suggesting that abnormal deposition of a-synuclein (aSyn) may originate in the peripheral autonomic nervous system, 1,2 coupled with evidence of a prion-like spread of synucleinopathy, 3 have generated much interest in evaluating enteric nervous system (ENS) aSyn to assess early PD neuropathology before disease spread and long before markers reliant on advanced disease are affected. 4 Several recent studies of aSyn staining in colonic tissue from living patients with PD report sensitivities ranging from 72% to a remarkable 100%. [5][6][7] However, the description of some degree of aSyn labeling in controls in these studies and reports of aSyn in colonic tissue from individuals without PD have raised concerns regarding specificity. 8,9 The aim of the present study was to optimize the immunohistochemical detection of aSyn in colonic biopsies by adapting the paraffin-embedded tissue (PET) blot, a method developed to increase sensitivity and specificity of detecting aggregated proteins in a related proteinopathy, Creutzfeldt-Jakob disease. The PET blot degrades nonaggregated proteins allowing the selective detection of remaining, presumably pathologic, protein aggregates.

Despite limited data on humans, previous studies suggest that there is an association between the duration of daily muscle activity and the proportion of type I muscle fibers. We quantified the activity of limb muscles in healthy men and women during normal use and compared these measurements with published reports on fiber-type proportions. Seven men (age range = 21-28 yr) and seven women (age range = 18-26 yr) participated in two 10-h recording sessions. Electromyogram (EMG) activity of four muscles in nondominant upper (first dorsal interosseus and biceps brachii) and lower limbs (vastus medialis and vastus lateralis) was recorded with surface electrodes. Hand and arm muscles were active for 18% of the recording time, whereas leg muscles were active for only 10% of the recording time. On average, upper-limb muscles were activated 67% more often than lower-limb muscles. When lower-limb muscles were activated, however, the mean amplitude of each burst was greater in leg muscles [18 and 17% maximum voluntary contraction (MVC)] compared with hand (8% MVC) and arm (6% MVC) muscles. Temporal association in activity between pairs of muscles was high for the two lower-limb muscles (r2 = 0.7) and relatively weak for the two upper-limb muscles (r2 = 0.09). Long-term muscle activity was only different between men and women for the biceps brachii muscle. We found no relation between duration of muscle activity in 10-h recordings and the reported values of type I fibers in men and women.

Poly(ethylene glycol) or PEG-based hydrogels provide a useful methodology for tissue engineering and the controlled-release of drugs within the central nervous system (CNS). To be successful, the local neuroinflammatory response to an implant must be well understood. Toward this end, the focus was to examine the localized recruitment and activation of microglia and astrocytes following implantation of PEG-based hydrogels in the brain. Because they are of clinical relevance and may impact brain tissue differently, hydrogels with different mass loss profiles were examined. At all time points, a needle penetration in sham animals evoked a greater astrocytic response than hydrogel conditions. The astrocyte response that ensued varied with degradation rate. An attenuated response was present in more slowly degrading and nondegrading conditions. Relative to sham, hydrogel conditions attenuated the acute microglial response during the week after implant. By 56 days, microglial levels in shams decreased below the observed response in slowly degrading and nondegradable gels, which remained constant overtime. Although the inflammatory response to PEG-based hydrogels was complex depending on degradation rates, the magnitude of the acute microglia response and the long-term astrocyte response were attenuated suggesting the use of these materials for drug and cell delivery to the CNS.

Degradable polymers have been used successfully in a wide variety of peripheral applications from tissue regeneration to drug delivery. These polymers induce little inflammatory response and appear to be well accepted by the host environment. Their use in the brain, for neural tissue reconstruction or drug delivery, also could be advantageous in treating neurodegenerative disorders. Because the brain has a unique immune response, a polymer that is compatible in the body may not be so in the brain. In the present study, polyethylene glycol (PEG)-based hydrogels were implanted into the striatum and cerebral cortex of nonhuman primates. Four months after implantation, brains were processed to evaluate the extent of astrogliosis and scaring, the presence of microglia/macrophages, and the extent of T-cell infiltration. Hydrogels with 20% w/v PEG implanted into the brain stimulated a slight increase in astrocytic and microglial/macrophage presence, as indicated by a small increase in glial fibrillary acidic protein (GFAP) and CD68 staining intensity. This increase was not substantially different from that found in the sham-implanted hemispheres of the brain. Staining for CD3+ T cells indicated no presence of peripheral T-cell infiltration. No gliotic scarring was seen in any implanted hemisphere. The combination of low density of GFAP-positive cells and CD68positive cells, the absence of T cells, and the lack of gliotic scarring suggest that this level of immune response is not indicative of immunorejection and that the PEG-based hydrogel has potential to be used in the primate brain for local drug delivery or neural tissue regeneration.