Rapamycin drives selection against a pathogenic heteroplasmic mitochondrial DNA mutation.

Mitochondrial DNA (mtDNA) mutations cause a variety of mitochondrial disorders for which effective treatments are lacking. Emerging data indicate that selective mitochondrial degradation through autophagy (mitophagy) plays a critical role in mitochondrial quality control. Inhibition of mammalian target of rapamycin (mTOR) kinase activity can activate mitophagy. To test the hypothesis that enhancing mitophagy would drive selection against dysfunctional mitochondria harboring higher levels of mutations, thereby decreasing mutation levels over time, we examined the impact of rapamycin on mutation levels in a human cytoplasmic hybrid (cybrid) cell line expressing a heteroplasmic mtDNA G11778A mutation, the most common cause of Leber's hereditary optic neuropathy. Inhibition of mTORC1/S6 kinase signaling by rapamycin induced colocalization of mitochondria with autophagosomes, and resulted in a striking progressive decrease in levels of the G11778A mutation and partial restoration of ATP levels. Rapamycin-induced upregulation of mitophagy was confirmed by electron microscopic evidence of increased autophagic vacuoles containing mitochondria-like organelles. The decreased mutational burden was not due to rapamycin-induced cell death or mtDNA depletion, as there was no significant difference in cytotoxicity/apoptosis or mtDNA copy number between rapamycin and vehicle-treated cells. These data demonstrate the potential for pharmacological inhibition of mTOR kinase activity to activate mitophagy as a strategy to drive selection against a heteroplasmic mtDNA G11778A mutation and raise the exciting possibility that rapamycin may have therapeutic potential for the treatment of mitochondrial disorders associated with heteroplasmic mtDNA mutations, although further studies are needed to determine if a similar strategy will be effective for other mutations and other cell types.

Properties of triple shape memory composites prepared via polymerization-induced phase separation.

Research in the field of shape memory polymers has recently witnessed the introduction of increasing complexity of material response, including such phenomena as triple/multishape behavior, temperature memory, and reversible actuation. Ordinarily, such complexity in physical behaviour is achieved through comparable complexity in material composition and synthesis. Seeking to achieve a triple shape behaviour with a simple route to materials synthesis, we introduce here a method that utilizes polymerization induced phase separation (PIPS) to yield the requisite combination of microstructure and composition. Thus, two blends incorporating epoxy and poly(ε-caprolactone) were developed using commercially available reactants, one featuring a semicrystalline epoxy and the other featuring an amorphous epoxy. We show that both blends exhibited distinct transition temperatures and three modulus-temperature plateaus needed for triple shape behaviour. Despite these similarities, their physical character at room temperature is vastly different: the semicrystalline epoxy material is elastomeric and the amorphous epoxy material is highly stiff. Characterization of the triple shape behaviour revealed an ability of both systems to fix two separate deformations independently, one by PCL crystallization and a second one by epoxy crystallization or vitrification, and recover both programmed shapes separately upon heating. Given the simplicity of fabrication, we envision application as multi-shape coatings, adhesives, and films.

Dysphagia in Parkinson's disease is responsive to levodopa.

The role of levodopa in the treatment of dysphagia in Parkinson's disease (PD) has recently been questioned. There are good reasons, however, to "question the question." In this essay, evidence from published literature and clinical experience is presented, as well as a critical review of the first meta-analysis to explore this issue. The evidence presented supports the traditional view that PD dysphagia is responsive to levodopa.

Increased melanoma risk in Parkinson disease: a prospective clinicopathological study.

OBJECTIVE: To evaluate the possible association of Parkinson disease (PD) and melanoma in North America. DESIGN, SETTING, AND PATIENTS: Thirty-one centers enrolled patients with idiopathic PD. At visit 1, a neurologist obtained a medical history. At visit 2, a dermatologist recorded melanoma risk factors, performed a whole-body examination, and performed a biopsy of lesions suggestive of melanoma for evaluation by a central dermatopathology laboratory. We compared overall prevalence of melanoma with prevalence calculated from the US Surveillance Epidemiology and End Results (SEER) cancer database and the American Academy of Dermatology skin cancer screening programs. RESULTS: A total of 2106 patients (mean [SD] age, 68.6 [10.6] years; duration of PD, 7.1 [5.7] years) completed the study. Most (84.8%) had received levodopa. Dermatology examinations revealed 346 pigmented lesions; dermatopathological findings confirmed 20 in situ melanomas (0.9%) and 4 invasive melanomas (0.2%). In addition, histories revealed 68 prior melanomas (3.2%). Prevalence (5-year limited duration) of invasive malignant melanoma in the US cohort of patients with PD (n = 1692) was 2.24-fold higher (95% confidence interval, 1.21-4.17) than expected in age- and sex-matched populations in the US SEER database. Age- or sex-adjusted relative risk of any melanoma for US patients was more than 7 times that expected from confirmed cases in American Academy of Dermatology skin cancer screening programs. CONCLUSIONS: Melanoma prevalence appears to be higher in patients with PD than in the general population. Despite difficulties in comparing other databases with this study population, the study supports increased melanoma screening in patients with PD.

Efficacy and safety of botulinum type A toxin (Dysport) in cervical dystonia: results of the first US randomized, double-blind, placebo-controlled study.

Botulinum toxin type A (Dysport) has been shown in European studies to be a safe and effective treatment for cervical dystonia. This multicenter, double-blind, randomized, controlled trial assessed the safety and efficacy of Dysport in cervical dystonia patients in the United States. Eighty patients were randomly assigned to receive one treatment with Dysport (500 units) or placebo. Participants were followed up for 4 to 20 weeks, until they needed further treatment. They were assessed at baseline and weeks 2, 4, 8, 12, 16, and 20 after treatment. Dysport was significantly more efficacious than placebo at weeks 4, 8, and 12 as assessed by the Toronto Western Spasmodic Torticollis Rating Scale (10-point vs. 3.8-point reduction in total score, respectively, at week 4; P < or = 0.013). Of participants in the Dysport group, 38% showed positive treatment response, compared to 16% in the placebo group (95% confidence interval, 0.02-0.41). The median duration of response to Dysport was 18.5 weeks. Side effects were generally similar in the two treatment groups; only blurred vision and weakness occurred significantly more often with Dysport. No participants in the Dysport group converted from negative to positive antibodies after treatment. These results confirm previous reports that Dysport (500 units) is safe, effective, and well-tolerated in patients with cervical dystonia.