Potent PDZ-Domain PICK1 Inhibitors that Modulate Amyloid Beta-Mediated Synaptic Dysfunction.

Protein interacting with C kinase (PICK1) is a scaffolding protein that is present in dendritic spines and interacts with a wide array of proteins through its PDZ domain. The best understood function of PICK1 is regulation of trafficking of AMPA receptors at neuronal synapses via its specific interaction with the AMPA GluA2 subunit. Disrupting the PICK1-GluA2 interaction has been shown to alter synaptic plasticity, a molecular mechanism of learning and memory. Lack of potent, selective inhibitors of the PICK1 PDZ domain has hindered efforts at exploring the PICK1-GluA2 interaction as a therapeutic target for neurological diseases. Here, we report the discovery of PICK1 small molecule inhibitors using a structure-based drug design strategy. The inhibitors stabilized surface GluA2, reduced Aß-induced rise in intracellular calcium concentrations in cultured neurons, and blocked long term depression in brain slices. These findings demonstrate that it is possible to identify potent, selective PICK1-GluA2 inhibitors which may prove useful for treatment of neurodegenerative disorders.

Lock and chop: A novel method for the generation of a PICK1 PDZ domain and piperidine-based inhibitor co-crystal structure.

The membrane protein interacting with kinase C1 (PICK1) plays a trafficking role in the internalization of neuron receptors such as the amino-3-hydroxyl-5-methyl-4-isoxazole-propionate (AMPA) receptor. Reduction of surface AMPA type receptors on neurons reduces synaptic communication leading to cognitive impairment in progressive neurodegenerative diseases such as Alzheimer disease. The internalization of AMPA receptors is mediated by the PDZ domain of PICK1 which binds to the GluA2 subunit of AMPA receptors and targets the receptor for internalization through endocytosis, reducing synaptic communication. We planned to block the PICK1-GluA2 protein-protein interaction with a small molecule inhibitor to stabilize surface AMPA receptors as a therapeutic possibility for neurodegenerative diseases. Using a fluorescence polarization assay, we identified compound BIO124 as a modest inhibitor of the PICK1-GluA2 interaction. We further tried to improve the binding affinity of BIO124 using structure-aided drug design but were unsuccessful in producing a co-crystal structure using previously reported crystallography methods for PICK1. Here, we present a novel method through which we generated a co-crystal structure of the PDZ domain of PICK1 bound to BIO124.

Small molecules inhibit the interaction of Nrf2 and the Keap1 Kelch domain through a non-covalent mechanism.

Keap1 binds to the Nrf2 transcription factor to promote its degradation, resulting in the loss of gene products that protect against oxidative stress. While cell-active small molecules have been identified that modify cysteines in Keap1 and effect the Nrf2 dependent pathway, few act through a non-covalent mechanism. We have identified and characterized several small molecule compounds that specifically bind to the Keap1 Kelch-DC domain as measured by NMR, native mass spectrometry and X-ray crystallography. One compound upregulates Nrf2 response genes measured by a luciferase cell reporter assay. The non-covalent inhibition strategy presents a reasonable course of action to avoid toxic side-effects due to non-specific cysteine modification.

Transorbital endoscopic repair of cerebrospinal fluid leaks.

OBJECTIVES: To describe an anatomic and clinical outcome study of transorbital neuroendoscopic surgical (TONES) for the repair of complex anterior cranial fossa (ACF) cerebrospinal fluid (CSF) leaks. DESIGN: Anatomic cadaver investigation and clinical outcomes evaluation. METHODS: An anatomic cadaver study was undertaken to determine the anatomic feasibility of the TONES approaches for repair of CSF leaks, and determine the optimal approaches for these repairs. A targeted outcome analysis was performed on 10 consecutive patients who underwent 12 ACF CSF leak repairs by TONES. RESULTS: The cadaver study demonstrated that the entire ACF can be accessed by TONES. Due to the rise and angulation of the orbital roof above the interorbital ACF, the precaruncular (PC) approach optimal for a coplanar target approach in the interorbital ACF, and the superior lid crease (SLC) trajectory is preferable for procedures involving the supraorbital ACF. There were no complications in the 12 clinical procedures. Fifty percent of the cases were revisions, referred after up to five previous craniotomies and endoscopic procedures; all TONES repairs were successful with a single operation. CONCLUSIONS: The use of TONES to repair ACF CSF leaks was demonstrated to be technically feasible in cadaver and clinical studies. The SLC approach was optimal for supraorbital ACF leaks; the PC approach was preferable for interorbital ACF pathology. TONES was shown to be highly effective for treating complex pathology that was refractory to correction through frontal craniotomy and /or transnasal endoscopy, providing safe, minimally disruptive direct coplanar routes for target approach and manipulation.

Transorbital neuroendoscopic surgery.

BACKGROUND: Transorbital neuroendoscopic surgery (TONES) pathways attempt to address some of the technical challenges of accessing laterally placed anterior skull base lesions or paramedian lesions that cross neurovascular structures. TONES approaches allow simultaneous coplanar visualization and working space above and below the skull base. OBJECTIVE: To present an anatomic study, a description of the surgical techniques, and an analysis of the safety and efficacy of 20 consecutive procedures using TONES for a variety of pathological conditions. METHODS: Sixteen patients underwent 20 TONES procedures for anterior skull base pathology, including repair of cerebrospinal leak, optic nerve decompression, repair of cranial base fractures, and removal of 3 skull base tumors. Ten patients were male, and 6 were female. The mean age at presentation was 44 years. Follow-up was 6 to 18 months with a mean of 9 months. RESULTS: There were no significant complications or treatment failures in any of the 20 procedures. A variety of pathological conditions were treated, including cerebrospinal fluid leaks, fractures, mass lesions, and tumors. The TONES approach provided up to 4 separate access ports with ample exposure for manipulation and correction of the pathology. CONCLUSION: This anatomic and prospective outcome study demonstrates that TONES provides safe and effective coplanar endoscopic access to the anterior and middle cranial base. These novel TONES approaches may be added to the wide range of published minimally invasive armamentarium when approaching challenging skull base pathology.

Bivalve cartilage inlay myringoplasty: an office-based procedure for closing small to medium-sized tympanic membrane perforations.

OBJECTIVE: To determine whether bivalve inlay cartilage-perichondrium myringoplasty (BCM) is successful in closing tympanic membrane perforations in an office setting. STUDY DESIGN: Retrospective case review. SUBJECTS AND METHODS: Adult patients with chronic perforations underwent BCM under local and topical anesthesia. Success was defined as complete closure of perforation at follow-up of at least 1 month. Predictors of success were identified by comparing the success and failure groups on pre- and postoperative pure tone average (PTA), patient demographics (age, gender), and characteristics of the perforations (size, location, duration, etiology). RESULTS: A total of 145 procedures were performed and the patients were followed for 1 to 78 months. The success rate for perforations smaller than 4 mm was 75 percent. Size of the perforation, and pre- and postoperative PTAs were significantly different between the two groups. The only significant predictors of success were preoperative PTA and size of perforation. CONCLUSIONS: BCM is a viable option for closure of small and medium-sized perforations in an office setting.

The evaluation and treatment of upper eyelid paralysis.

Patients with upper lid paralysis suffer from a loss of the blink reflex/response in the affected eye, leaving the eye vulnerable to a host of predatory insults. Partial or total impairment of the orbicularis oculi muscle, lagophthalmos, disruption of the lacrimal apparatus, upper lid retraction, and the unopposed pull of gravity on the surrounding paralyzed tissues all contribute to increased corneal exposure and an increased risk of exposure keratitis. Management of the upper lid in these patients must therefore focus on restoration of the effects of the blink reflex/response and prevention of corneal exposure. Relevant anatomy and pathophysiology are discussed. The initial treatment is supportive, with surgery reserved for those patients that fall into two categories: those who have failed nonsurgical treatment to protect the cornea and those who have been treated effectively with conservative measures but are faced with the prospect of long-term or permanent paralysis. A variety of surgical procedures that may be classified as either static or dynamic are discussed. Standard static procedures include lid loading and tarsorrhaphy, whereas the palpebral spring implant and the temporalis muscle transfer are classified as dynamic. The goal of the corrective procedures is to allow complete eye closure, thereby providing corneal protection, with minimal (1 mm or less) ptosis in the open position.

The evaluation and treatment of lower eyelid paralysis.

The lower eyelid conforms precisely across its length to the complex topography of the cornea, conjunctiva, and globe. Along with the upper eyelid, it protects the eye from foreign bodies, prevents desiccation, and helps circulate the tear film from its origin in the lacrimal gland to its drainage at the lacrimal puncta. Paralysis of the lower eyelid may result in ectropion, lid laxity, epiphora, and lagophthalmos. This article presents a structural approach to the evaluation and treatment of lower eyelid paralysis and describes the surgical procedures designed to correct the three-dimensional anatomic abnormalities underlying this disorder. These procedures are frequently performed in conjunction with upper lid procedures that are described in a previous article by Bergeron and Moe in this issue of the journal.