Faculty Bibliography

Purpose/UNASSIGNED:We examined structural and functional changes in the outer retina of a mouse model of glaucoma. We examined whether these changes are a secondary consequence of damage in the inner retina and whether neuroprotection of the inner retina also prevents outer retinal changes. Methods/UNASSIGNED:We used an established microbead occlusion model of glaucoma whereby intraocular pressure (IOP) was elevated. Specific antibodies were used to label rod and cone bipolar cells (BCs), horizontal cells (HCs), and retinal ganglion cells (RGCs), as well as synaptic components in control and glaucomatous eyes, to assess structural damage and cell loss. ERG recordings were made to assess outer retina function. Results/UNASSIGNED:We found structural and functional damage of BCs, including significant cell loss and dendritic/axonal remodeling of HCs, following IOP elevation. The first significant loss of both BCs occurred at 4 to 5 weeks after microbead injection. However, early changes in the dendritic structure of RGCs were observed at 3 weeks, but significant changes in the rod BC axon terminal structure were not seen until 4 weeks. We found that protection of inner retinal neurons in glaucomatous eyes by pharmacological blockade of gap junctions or genetic ablation of connexin 36 largely prevented outer retinal damage. Conclusions/UNASSIGNED:Together, our results indicate that outer retinal impairments in glaucoma are a secondary sequalae of primary damage in the inner retina. The finding that neuroprotection of the inner retina can also prevent outer retinal damage has important implications with regard to the targets for effective neuroprotective therapy.

Recent experiments in the developing mammalian visual cortex have revealed that gap junctions couple excitatory cells and potentially influence the formation of chemical synapses. In particular, cells that were coupled by a gap junction during development tend to share an orientation preference and are preferentially coupled by a chemical synapse in the adult cortex, a property that is diminished when gap junctions are blocked. In this work, we construct a simplified model of the developing mouse visual cortex including spike-timing-dependent plasticity of both the feedforward synaptic inputs and recurrent cortical synapses. We use this model to show that synchrony among gap-junction-coupled cells underlies their preference to form strong recurrent synapses and develop similar orientation preference; this effect decreases with an increase in coupling density. Additionally, we demonstrate that gap-junction coupling works, together with the relative timing of synaptic development of the feedforward and recurrent synapses, to determine the resulting cortical map of orientation preference.

OBJECTIVE:Fibroblast growth factor homologous factors (FHFs) are brain and cardiac sodium channel-binding proteins that modulate channel density and inactivation gating. A recurrent de novo gain-of-function missense mutation in the FHF1(FGF12) gene (p.Arg52His) is associated with early infantile epileptic encephalopathy 47 (EIEE47; Online Mendelian Inheritance in Man database 617166). To determine whether the FHF1 missense mutation is sufficient to cause EIEE and to establish an animal model for EIEE47, we sought to engineer this mutation into mice. METHODS:protein. RESULTS:mice prior to seizure. SIGNIFICANCE/CONCLUSIONS:1.6 functional axis underlying altered brain sodium channel gating in epileptic encephalopathy.

OBJECTIVE:The objective of the study was to evaluate the feasibility and acceptability of mobile health (mHealth) phosphorus management programs in hemodialysis (HD) patients. METHODS:Patients receiving thrice-weekly HD who had 3-month average serum phosphorus of >5.5 mg/dL were randomized to one of the three self-directed phosphorus management programs delivered using tablet PCs: (1) educational videos and handouts (Education), (2) education intervention plus mobile self-monitoring with email feedback (Monitoring), or (3) education and monitoring interventions plus social cognitive theory-based behavioral videos (Combined). Feasibility and acceptability were assessed based on enrollment and retention and training needs (feasibility) and adherence to self-monitoring and reported satisfaction (acceptability). RESULTS:Of 312 patients, 56 expressed interest, and 40 were enrolled. The majority of participants (80%) completed the 6-month study; none withdrew for intervention-related reasons. The Monitoring and Combined groups received 44 ± 15 minutes of technology training, which was considered adequate by most (75%). Self-monitoring rates were initially high, with 78% and 71% of the participants recording at least one meal and phosphate binder in week 1, respectively, but decreased over time to 15% and 9% in the final week. Most participants reported that self-monitoring helped them stay motivated (64%), track nutrients (80%), and understand how to change diet (76%), and nearly two-thirds of participants (64%) stated that they would like to continue using the tablet PC to manage their health. However, few participants (16%) indicated that self-monitoring was worth the effort. The Monitoring and Combined groups did not differ from the Education group in study outcomes. CONCLUSION/CONCLUSIONS:Although the mHealth programs were generally well received, self-monitoring rates decreased substantially over time and were unaffected by social cognitive theory-based videos. Self-directed mHealth programs may be a useful adjunct to standard care but should be compared to more resource intensive programs (e.g., involving more "live" contact with a dietitian) to determine overall cost-effectiveness and role in HD care.

Tau immunotherapies have advanced from proof-of-concept studies to over a dozen clinical trials for Alzheimer's disease (AD) and other tauopathies. Mechanistic studies in animal and culture models have provided valuable insight into how these therapies may work but multiple pathways are likely involved. Different groups have emphasized the importance of intracellular vs extracellular antibody-mediated clearance of the tau protein and there is no consensus on which pool of tau should ideally be targeted. Likewise, various normal and disease-selective epitopes are being targeted, and the antibody isotypes either favor phagocytosis of the tau-antibody complex or are neutral in that aspect. Most of the clinical trials are in early stages, thus their efficacy is not yet known, but all have been without any major adverse effects and some have reported target engagement. A few have been discontinued. One in phase I, presumably because of a poor pharmacokinetic profile, and three in phase II for a lack of efficacy although this trial stage is not well powered for efficacy measures. In these phase II studies, trials with two antibodies in patients with progressive supranuclear palsy or other primary tauopathies were halted but are continuing in patients with AD, and one antibody trial was stopped in early-stage AD but is continuing in moderate AD. These three antibodies have been reported to only work extracellularly and tau is not increased in the cerebrospinal fluid of primary tauopathies, which may explain the failures of two of them. In the discontinued AD trial, there are some concerns about how much of extracellular tau contains the N-terminal epitope that is being targeted. In addition, extracellular tau is only a small part of total tau, compared to intracellular tau. Targeting only the former may not be sufficient for functional benefits. Given these outcomes, decision makers within the pharmaceutical companies who green light these trials should attempt to target tau not only extracellularly but also intracellularly to increase their chances of success. Hopefully, some of the ongoing trials will provide some functional benefits to the large number of patients with tauopathies.

Rhythms of the brain are generated by neural oscillations across multiple frequencies. These oscillations can be decomposed into distinct frequency intervals associated with specific physiological processes. In practice, the number and ranges of decodable frequency intervals are determined by sampling parameters, often ignored by researchers. To improve the situation, we report on an open toolbox with a graphical user interface for decoding rhythms of the brain system (DREAM). We provide worked examples of DREAM to investigate frequency-specific performance of both neural (spontaneous brain activity) and neurobehavioral (in-scanner head motion) oscillations. DREAM decoded the head motion oscillations and uncovered that younger children moved their heads more than older children across all five frequency intervals whereas boys moved more than girls in the age of 7 to 9 years. It is interesting that the higher frequency bands contain more head movements, and showed stronger age-motion associations but weaker sex-motion interactions. Using data from the Human Connectome Project, DREAM mapped the amplitude of these neural oscillations into multiple frequency bands and evaluated their test-retest reliability. The resting-state brain ranks its spontaneous oscillation's amplitudes spatially from high in ventral-temporal areas to low in ventral-occipital areas when the frequency band increased from low to high, while those in part of parietal and ventral frontal regions are reversed. The higher frequency bands exhibited more reliable amplitude measurements, implying more inter-individual variability of the amplitudes for the higher frequency bands. In summary, DREAM adds a reliable and valid tool to mapping human brain function from a multiple-frequency window into brain waves.

Congenital myasthenia (CM) is a devastating neuromuscular disease, and mutations in DOK7, an adaptor protein that is crucial for forming and maintaining neuromuscular synapses, are a major cause of CM^1,2. The most common disease-causing mutation (DOK7^{1124_1127 dup}) truncates DOK7 and leads to the loss of two tyrosine residues that are phosphorylated and recruit CRK proteins, which are important for anchoring acetylcholine receptors at synapses. Here we describe a mouse model of this common form of CM (Dok7^CM mice) and a mouse with point mutations in the two tyrosine residues (Dok7^2YF). We show that Dok7^CM mice had severe deficits in neuromuscular synapse formation that caused neonatal lethality. Unexpectedly, these deficits were due to a severe deficiency in phosphorylation and activation of muscle-specific kinase (MUSK) rather than a deficiency in DOK7 tyrosine phosphorylation. We developed agonist antibodies against MUSK and show that these antibodies restored neuromuscular synapse formation and prevented neonatal lethality and late-onset disease in Dok7^CM mice. These findings identify an unexpected cause for disease and a potential therapy for both DOK7 CM and other forms of CM caused by mutations in AGRIN, LRP4 or MUSK, and illustrate the potential of targeted therapy to rescue congenital lethality.

The molecular structure of nanothreads produced by the slow compression of¹³C4-furan was studied by advanced solid-state NMR. Spectral editing showed that >95% of carbon atoms were bonded to one hydrogen (C-H) and that there were 2-4% CH2, 0.6% CO, and <0.3% CH3groups. Alkenes accounted for 18% of the CH moieties, while trapped, unreacted furan made up 7%. Two-dimensional (2D)¹³C-¹³C and¹H-¹³C NMR identified 12% of all carbon in asymmetric O-CHCH-CH-CH- and 24% in symmetric O-CH-CHCH-CH- rings. While the former represented defects or chain ends, some of the latter appeared to form repeating thread segments. Around 10% of carbon atoms were found in highly ordered, fully saturated nanothread segments. Unusually slow¹³C spin-exchange with sites outside the perfect thread segments documented a length of at least 14 bonds; the small width of the perfect-thread signals also implied a fairly long, regular structure. Carbons in the perfect threads underwent relatively slow spin-lattice relaxation, indicating slow spin exchange with other threads and smaller amplitude motions. Through partial inversion recovery, the signals of the perfect threads were observed and analyzed selectively. Previously consideredsyn-threads with four different C-H bond orientations were ruled out by centerband-only detection of exchange NMR, which was, on the contrary, consistent withanti-threads. The observed¹³C chemical shifts were matched well by quantum-chemical calculations foranti-threads but not for more complex structures likesyn/anti-threads. These observations represent the first direct determination of the atomic-level structure of fully saturated nanothreads.
Copyright

Point-of-care (POC) testing for Toxoplasma infection has the potential to revolutionize diagnosis and management of toxoplasmosis, especially in high-risk populations in areas with significant environmental contamination and poor health infrastructure precluding appropriate follow-up and preventing access to medical care. Toxoplasmosis is a significant public health challenge in Morocco, with a relatively heavy burden of infection and, to this point, minimal investment nationally to address this infection. Herein, we analyze the performance of a novel, low-cost rapid test using fingerstick-derived whole blood from 632 women (82 of whom were pregnant) from slums, educational centers, and from nomad groups across different geographical regions (i.e. oceanic, mountainous) of Morocco. The POC test was highly sensitive and specific from all settings. In the first group of 283 women, sera were tested by Platelia ELISA IgG and IgM along with fingerstick whole blood test. Then a matrix study with 349 women was performed in which fingerstick- POC test results and serum obtained by venipuncture contemporaneously were compared. These results show high POC test performance (Sensitivity: 96.4% [IC95 90.6-98.9%]; Specificity: 99.6% [IC95 97.3-99.9%]), and high prevalence of Toxoplasma infection among women living in rural and mountainous areas, and in urban areas with lower educational levels. The high performance of POC test confirms that it can reduce the need for venipuncture and clinical infrastructure in a low resource setting. It can be used to efficiently perform seroprevalence determinations in large group settings across a range of demographics, and potentially expands healthcare access, thereby preventing human suffering.

G protein-coupled receptors (GPCRs) are the most common targets of drug discovery. However, the similarity between related GPCRs combined with the complex spatiotemporal dynamics of receptor activation in vivo has hindered drug development. Photopharmacology offers the possibility of using light to control the location and timing of drug action by incorporating a photoisomerizable azobenzene into a GPCR ligand, enabling rapid and reversible switching between an inactive and active configuration. Recent advances in this area include (i) photoagonists and photoantagonists that directly control receptor activity but are nonselective because they bind conserved sites, and (ii) photoallosteric modulators that bind selectively to nonconserved sites but indirectly control receptor activity by modulating the response to endogenous ligand. In this study, we designed a photoswitchable allosteric agonist that targets a nonconserved allosteric site for selectivity and activates the receptor on its own to provide direct control. This work culminated in the development of aBINA, a photoswitchable allosteric agonist that selectively activates the G_i/o-coupled metabotropic glutamate receptor 2 (mGluR2). aBINA is the first example of a new class of precision drugs for GPCRs and other clinically important signaling proteins.