Drug delivery to the brain is highly restricted, since compounds must cross a series of structural and metabolic barriers to reach their final destination, often a cellular compartment such as ...neurons, microglia, or astrocytes. The primary barriers to the central nervous system are the blood-brain and blood-cerebrospinal fluid barriers. Through structural modifications, including the presence of tight junctions that greatly limit paracellular transport, the cells that make up these barriers restrict diffusion of many pharmaceutically active compounds. In addition, the cells that comprise the blood-brain and blood-cerebrospinal fluid barriers express multiple ATP-dependent, membrane-bound, efflux transporters, such as members of the multidrug resistance-associated protein (MRP) family, which contribute to lowered drug accumulation. A relatively new concept in brain drug distribution just beginning to be explored is the possibility that cellular components of the brain parenchyma could act as a "second" barrier to brain permeation of pharmacological agents via expression of many of the same transporters. Indeed, efflux transporters expressed in brain parenchyma may facilitate the overall export of xenobiotics from the central nervous system, essentially handing them off to the barrier tissues. We propose that these primary and secondary barriers work in tandem to limit overall accumulation and distribution of xenobiotics in the central nervous system. The present review summarizes recent knowledge in this area and emphasizes the clinical significance of MRP transporter expression in a variety of neurological disorders.
Pharmacotherapy of central nervous system (CNS) disorders (e.g., neurodegenerative diseases, epilepsy, brain cancer, and neuro-AIDS) is limited by the blood-brain barrier. P-glycoprotein, an ...ATP-driven, drug efflux transporter, is a critical element of that barrier. High level of expression, luminal membrane location, multispecificity, and high transport potency make P-glycoprotein a selective gatekeeper of the blood-brain barrier and thus a primary obstacle to drug delivery into the brain. As such, P-glycoprotein limits entry into the CNS for a large number of prescribed drugs, contributes to the poor success rate of CNS drug candidates, and probably contributes to patient-to-patient variability in response to CNS pharmacotherapy. Modulating P-glycoprotein could therefore improve drug delivery into the brain. Here we review the current understanding of signaling mechanisms responsible for the modulation of P-glycoprotein activity/expression at the blood-brain barrier with an emphasis on recent studies from our laboratories. Using intact brain capillaries from rats and mice, we have identified multiple extracellular and intracellular signals that regulate this transporter; several signaling pathways have been mapped. Three pathways are triggered by elements of the brain's innate immune response, one by glutamate, one by xenobiotic-nuclear receptor (pregnane X receptor) interactions, and one by elevated beta-amyloid levels. Signaling is complex, with several pathways sharing common signaling elements tumor necrosis factor (TNF) receptor 1, endothelin (ET) B receptor, protein kinase C, and nitric-oxide synthase), suggesting a regulatory network. Several pathways include autocrine/paracrine elements, involving release of the proinflammatory cytokine, TNF-alpha, and the polypeptide hormone, ET-1. Finally, several steps in signaling are potential therapeutic targets that could be used to modulate P-glycoprotein activity in the clinic.
Genetic amplification, mutation, and translocation are known to play a causal role in the upregulation of an oncogene in cancer cells. Here, we report an emerging role of microRNA, the epigenetic ...deregulation of which may also lead to this oncogenic activation. SOX4, an oncogene belonging to the SRY-related high mobility group box family, was found to be overexpressed (P < 0.005) in endometrial tumors (n = 74) compared with uninvolved controls (n = 20). This gene is computationally predicted to be the target of a microRNA, miR-129-2. When compared with the matched endometria, the expression of miR-129-2 was lost in 27 of 31 primary endometrial tumors that also showed a concomitant gain of SOX4 expression (P < 0.001). This inverse relationship is associated with hypermethylation of the miR-129-2 CpG island, which was observed in endometrial cancer cell lines (n = 6) and 68% of 117 endometrioid endometrial tumors analyzed. Reactivation of miR-129-2 in cancer cells by pharmacologic induction of histone acetylation and DNA demethylation resulted in decreased SOX4 expression. In addition, restoration of miR-129-2 by cell transfection led to decreased SOX4 expression and reduced proliferation of cancer cells. Further analysis found a significant correlation of hypermethylated miR-129-2 with microsatellite instability and MLH1 methylation status (P < 0.001) and poor overall survival (P < 0.039) in patients. Therefore, these results imply that the aberrant expression of SOX4 is, in part, caused by epigenetic repression of miR-129-2 in endometrial cancer. Unlike the notion that promoter hypomethylation may upregulate an oncogene, we present a new paradigm in which hypermethylation-mediated silencing of a microRNA derepresses its oncogenic target in cancer cells.
Since amphibian declines were first proposed as a global phenomenon over a quarter century ago, the conservation community has made little progress in halting or reversing these trends. The early ...search for a "smoking gun" was replaced with the expectation that declines are caused by multiple drivers. While field observations and experiments have identified factors leading to increased local extinction risk, evidence for effects of these drivers is lacking at large spatial scales. Here, we use observations of 389 time-series of 83 species and complexes from 61 study areas across North America to test the effects of 4 of the major hypothesized drivers of declines. While we find that local amphibian populations are being lost from metapopulations at an average rate of 3.79% per year, these declines are not related to any particular threat at the continental scale; likewise the effect of each stressor is variable at regional scales. This result - that exposure to threats varies spatially, and populations vary in their response - provides little generality in the development of conservation strategies. Greater emphasis on local solutions to this globally shared phenomenon is needed.
Tau: From research to clinical development Holtzman, David M; Carrillo, Maria C; Hendrix, James A ...
Alzheimer's & dementia,
October 2016, Letnik:
12, Številka:
10
Journal Article
Recenzirano
Abstract Alzheimer's Association Research Roundtable Fall 2015—Tau: From research to clinical development. Tau pathology is recognized as the key driver of disease progression in Alzheimer's and ...other neurodegenerative diseases. Although this makes tau an attractive target for the development of novel diagnostic and therapeutic strategies, the mechanisms underlying the onset and progression of tau-related neurotoxicity remain elusive. Recent strides in the development of sophisticated preclinical models and the emergence of tau PET imaging and fluid biomarkers provide new opportunities to increase our understanding of tau biology, overcome translational challenges, and accelerate the advancement of tau therapeutics from bench to bedside. With this in mind, the Alzheimer's Association convened a Research Roundtable in October 2015, bringing together experts from academia, industry, and regulatory agencies to discuss the latest understanding of tau pathogenic pathways and review the evolution of tau therapeutics and biomarkers currently in development. The meeting provided a forum to share experience and expertise with the common goal of advancing the discovery and development of new treatment strategies and expediting the design and implementation of efficient clinical trials.
Why are monetary authorities not elected like fiscal authorities are? Advanced economies pair an elected fiscal authority with an independent monetary authority. Replicating the advanced economies' ...structure with authorities microfounded by a political economy model shows that this structure is the solution to a constrained mechanism design problem that overcomes time inconsistency and results in the highest possible welfare. Goal and instrument independence, singly and in combination, are insufficient to minimize time inconsistency, though their combination is necessary.
Summary Background In preclinical studies, davunetide promoted microtubule stability and reduced tau phosphorylation. Because progressive supranuclear palsy (PSP) is linked to tau pathology, ...davunetide could be a treatment for PSP. We assessed the safety and efficacy of davunetide in patients with PSP. Methods In a double-blind, parallel group, phase 2/3 trial, participants were randomly assigned with permuted blocks in a 1:1 ratio to davunetide (30 mg twice daily, intranasally) or placebo for 52 weeks at 48 centres in Australia, Canada, France, Germany, the UK, and the USA. Participants met the modified Neuroprotection and Natural History in Parkinson Plus Syndrome study criteria for PSP. Primary endpoints were the change from baseline in PSP Rating Scale (PSPRS) and Schwab and England Activities of Daily Living (SEADL) scale at up to 52 weeks. All participants and study personnel were masked to treatment assignment. Analysis was by intention to treat. The trial is registered with Clinicaltrials.gov , number NCT01110720. Findings 313 participants were randomly assigned to davunetide (n=157) or to placebo (n=156), and 241 (77%) completed the study (118 and 156 in the davunetide and placebo groups, respectively). There were no differences in the davunetide and placebo groups in the baseline PSPRS and SEADL. The davunetide and placebo groups did not differ in the change from baseline in PSPRS (median 11·8 95% CI 10·5 to 13·0 vs 11·8 10·5 to 13·0, respectively, p=0·41) or SEADL (−0·20 −0·20 to −0·17 vs −0·20 −0·22 to −0·17, respectively, p=0·92). 54 serious adverse events were reported in each of the treatment groups, including 11 deaths in the davunetide group and ten in the placebo group. The frequency of nasal adverse events was greater in the davunetide group than in the placebo group (epistaxis 18 12% of 156 vs 13 8% of 156, rhinorrhoea 15 10% vs eight 5%, and nasal discomfort 15 10% vs one <1%). Interpretation Davunetide is not an effective treatment for PSP. Clinical trials of disease-modifying treatment are feasible in patients with PSP and should be pursued with other promising tau-directed treatments. Funding Allon Therapeutics.
Most autistic adults struggle with mental health problems, and traditional mental
health services generally do not meet their needs. This study used qualitative
methods to identify ways to improve ...community mental health services for
autistic adults for treatment of their co-occurring psychiatric conditions. We
conducted semistructured, open-ended interviews with 22 autistic adults with
mental healthcare experience, 44 community mental health clinicians, and 11
community mental health agency leaders in the United States. The participants
identified clinician-, client-, and systems-level barriers and facilitators to
providing quality mental healthcare to autistic adults. Across all three
stakeholder groups, most of the reported barriers involved clinicians’ limited
knowledge, lack of experience, poor competence, and low confidence working with
autistic adults. All three groups also discussed the disconnect between the
community mental health and developmental disabilities systems, which can result
in autistic adults being turned away from services when they contact the mental
health division and disclose their autism diagnosis during the intake process.
Further efforts are needed to train clinicians to work more effectively with
autistic adults and to increase coordination between the mental health and
developmental disabilities systems.
Lay Abstract
Most autistic adults struggle with mental health problems, such as anxiety
and depression. However, they often have trouble finding effective mental
health treatment in their community. The goal of this study was to identify
ways to improve community mental health services for autistic adults. We
interviewed 22 autistic adults with mental healthcare experience, 44
community mental health clinicians (outpatient therapists, case managers,
and intake coordinators), and 11 community mental health agency leaders in
the United States. Our participants identified a variety of barriers to
providing quality mental healthcare to autistic adults. Across all three
groups, most of the reported barriers involved clinicians’ limited
knowledge, lack of experience, poor competence, and low confidence working
with autistic adults. All three groups also discussed the disconnect between
the community mental health and developmental disabilities systems and the
need to improve communication between these two systems. Further efforts are
needed to train clinicians and provide follow-up consultation to work more
effectively with autistic adults. A common suggestion from all three groups
was to include autistic adults in creating and delivering the clinician
training. The autistic participants provided concrete recommendations for
clinicians, such as consider sensory issues, slow the pace, incorporate
special interests, use direct language, and set clear expectations. Our
findings also highlight a need for community education about co-occurring
psychiatric conditions with autism and available treatments, in order to
increase awareness about treatment options.
Neuropsychiatric symptoms (NPSs) are hallmarks of Alzheimer's disease (AD), causing substantial distress for both people with dementia and their caregivers, and contributing to early ...institutionalization. They are among the earliest signs and symptoms of neurocognitive disorders and incipient cognitive decline, yet are under-recognized and often challenging to treat. With this in mind, the Alzheimer's Association convened a Research Roundtable in May 2016, bringing together experts from academia, industry, and regulatory agencies to discuss the latest understanding of NPSs and review the development of therapeutics and biomarkers of NPSs in AD. This review will explore the neurobiology of NPSs in AD and specific symptoms common in AD such as psychosis, agitation, apathy, depression, and sleep disturbances. In addition, clinical trial designs for NPSs in AD and regulatory considerations will be discussed.
PDF
