Interaction of micropatterned topographical and biochemical cues to direct neurite growth from spiral ganglion neurons.

Functional outcomes with neural prosthetic devices, such as cochlear implants, are limited in part due to physical separation between the stimulating elements and the neurons they stimulate. One strategy to close this gap aims to precisely guide neurite regeneration to position the neurites in closer proximity to electrode arrays. Here, we explore the ability of micropatterned biochemical and topographic guidance cues, singly and in combination, to direct the growth of spiral ganglion neuron (SGN) neurites, the neurons targeted by cochlear implants. Photopolymerization of methacrylate monomers was used to form unidirectional topographical features of ridges and grooves in addition to multidirectional patterns with 90o angle turns. Microcontact printing was also used to create similar uni- and multi-directional patterns of peptides on polymer surfaces. Biochemical cues included peptides that facilitate (laminin, LN) or repel (EphA4-Fc) neurite growth. On flat surfaces, SGN neurites preferentially grew on LN-coated stripes and avoided EphA4-Fc-coated stripes. LN or EphA4-Fc was selectively adsorbed onto the ridges or grooves to test the neurite response to a combination of topographical and biochemical cues. Coating the ridges with EphA4-Fc and grooves with LN lead to enhanced SGN alignment to topographical patterns. Conversely, EphA4-Fc coating on the grooves or LN coating on the ridges tended to disrupt alignment to topographical patterns. SGN neurites respond to combinations of topographical and biochemical cues and surface patterning that leverages both cues enhance guided neurite growth.

Short or Minimum Incision Deep Plane/Extended Deep Plane Facelift/Rhytidectomy.

The mini facelift, often referred to as short scar or minimum incision facelift or rhytidectomy, is a facial rejuvenation procedure with limited incisions. It aims to lift and tighten the superficial musculo-aponeurotic system to restore the lower midface and the mandibular contour, thus eliminating undesirable jowls. By performing the deep plane or extended deep plane facelift with short incisions, the midface and upper neck can also be improved without the full face and neck incisions as in the typical rhytidectomy. With its decreased operative time and expense, rapid recovery, less complications, as well as more limited incisions with resultant less evidence of scars, mini facelift techniques have boomed over a decade for younger patients who seek facial rejuvenation. We describe our concept of the short or minimum incision deep plane/extended deep plane facelift or rhytidectomy and address what results can be expected.

Melanoma Characteristics in Patients with a History of UV Tanning Bed Usage.

OBJECTIVE: The purpose of this study was to evaluate the effect of tanning bed use on the behavior of subsequent melanomas. METHODS: Cases of invasive cutaneous melanoma who completed a baseline questionnaire within 1 year of biopsy were ascertained using an institutional registry. Patients were categorized into one of two groups: (1) no history of UV tanning bed usage or (2) any history of tanning bed usage. Data analysis looked for group differences on the following variables: TNM staging, mitotic rate, family history of melanoma, and basic demographic variables. RESULTS: Among 141 cases, a higher percentage of women (48.28%) reported tanning bed usage compared to men (26.51%, P < .01). Additionally, the average age at biopsy for people who reported tanning bed usage was significantly lower compared to those who had not reported using a tanning bed. There was no significant difference in stage at presentation (P = .56). Those with tanning bed usage presented significantly less often with melanoma of unknown primary (MUP). After controlling for the effects of gender and nodal status, tanning bed usage was not a significant independent predictor of 5 year overall survival. CONCLUSIONS: If we remove the subject with MUP on the basis that more of these are mucosal in origin, lower TNM stage at presentation are found in patients with no tanning bed melanoma compared to those with history of tanning bed usage. In addition, tanning bed patients are younger and more likely female but with an equivalent mortality rate. LEVEL OF EVIDENCE: Case Series.

Nf2 Mutation in Schwann Cells Delays Functional Neural Recovery Following Injury.

Merlin is the protein product of the NF2 tumor suppressor gene. Germline NF2 mutation leads to neurofibromatosis type 2 (NF2), characterized by multiple intracranial and spinal schwannomas. Patients with NF2 also frequently develop peripheral neuropathies. While the role of merlin in SC neoplasia is well established, its role in SC homeostasis is less defined. Here we explore the role of merlin in SC responses to nerve injury and their ability to support axon regeneration. We performed sciatic nerve crush in wild-type (WT) and in P0SchΔ39-121 transgenic mice that express a dominant negative Nf2 isoform in SCs. Recovery of nerve function was assessed by measuring mean contact paw area on a pressure pad 7, 21, 60, and 90 days following nerve injury and by nerve conduction assays at 90 days following injury. After 90 days, the nerves were harvested and axon regeneration was quantified stereologically. Myelin ultrastructure was analyzed by electron microscopy. Functional studies showed delayed nerve regeneration in Nf2 mutant mice compared to the WT mice. Delayed neural recovery correlated with a reduced density of regenerated axons and increased endoneurial space in mutants compared to WT mice. Nevertheless, functional and nerve conduction measures ultimately recovered to similar levels in WT and Nf2 mutant mice, while there was a small (∼17%) reduction in the percent of regenerated axons in the Nf2 mutant mice. The data suggest that merlin function in SCs regulates neural ultrastructure and facilitates neural regeneration, in addition to its role in SC neoplasia.

Radiocontrast Dye Extravasation During Sialography.

OBJECTIVE: Evaluate the pathophysiology of contrast extravasation. METHODS: Two hundred fifty-five sialograms at the University of Iowa from 2008 to 2016 were reviewed. RESULTS: Twelve sialograms (4.7% of total) were identified with main ductal extravasation. In each case, ductal stenosis as a diagnosis was supported by clinical history and the finding of difficulty in advancing the cannula into the duct during sialography. In all but 1 case, extravasation occurred at the distal duct with no further imaging of the ductal system. Each of the 5 cases treated with sialendoscopy with or without gland resection confirmed stenosis. Ultrasound evaluation of 5 of the cases detected ductal dilation in 4 (80%). Six of 11 computed tomography scans done before the sialogram were interpreted as normal with indirect evidence for ductal stenosis (duct dilation) reported in only 1. All extravasations were associated with either stricture alone or stricture with stone (1 case). CONCLUSION: Radiocontrast extravasation from the main duct during sialography is highly associated with the presence of ductal stricture. In our experience, the inability to fill the ductal system with radiocontrast is a useful sialographic finding that correlated closely with anatomic abnormality rather than technical error. The frequent finding of extravasation of radiocontrast supports the use of water soluble contrast.

Tuning Surface and Topographical Features to Investigate Competitive Guidance of Spiral Ganglion Neurons.

Cochlear Implants (CIs) suffer from limited tonal resolution due, in large part, to spatial separation between stimulating electrode arrays and primary neural receptors. In this work, a combination of physical and chemical micropatterns, formed on acrylate polymers, are used to direct the growth of primary spiral ganglion neurons (SGNs), the inner ear neurons. Utilizing the inherent temporal and spatial control of photopolymerization, physical microgrooves are fabricated using a photomask in a single step process. Biochemical patterns are generated by adsorbing laminin, a cell adhesion protein, to acrylate polymer surfaces followed by irradiation through a photomask with UV light to deactivate protein in exposed areas and generate parallel biochemical patterns. Laminin deactivation was shown increase as a function of UV light exposure while remaining adsorbed to the polymer surface. SGN neurites show alignment to both biochemical and physical patterns when evaluated individually. Competing biochemical and physical patterns were also examined. The relative guiding strength of physical cues was varied by independently changing both the amplitude and the band spacing of the microgrooves, with higher amplitudes and shorter band spacing providing cues that more effective guide neurite growth. SGN neurites aligned to laminin patterns with lower physical pattern amplitude and thus weaker physical cues. Alignment of SGNs shifted toward the physical pattern with higher amplitude and lower periodicity patterns which represent stronger cues. These results demonstrate the ability of photopolymerized microfeatures to modulate alignment of inner ear neurites even in the presence of conflicting physical and biochemical cues laying the groundwork for next generation cochlear implants and neural prosthetic devices.

Inner ear supporting cells protect hair cells by secreting HSP70.

Mechanosensory hair cells are the receptor cells of hearing and balance. Hair cells are sensitive to death from exposure to therapeutic drugs with ototoxic side effects, including aminoglycoside antibiotics and cisplatin. We recently showed that the induction of heat shock protein 70 (HSP70) inhibits ototoxic drug-induced hair cell death. Here, we examined the mechanisms underlying the protective effect of HSP70. In response to heat shock, HSP70 was induced in glia-like supporting cells but not in hair cells. Adenovirus-mediated infection of supporting cells with Hsp70 inhibited hair cell death. Coculture with heat-shocked utricles protected nonheat-shocked utricles against hair cell death. When heat-shocked utricles from Hsp70-/- mice were used in cocultures, protection was abolished in both the heat-shocked utricles and the nonheat-shocked utricles. HSP70 was detected by ELISA in the media surrounding heat-shocked utricles, and depletion of HSP70 from the media abolished the protective effect of heat shock, suggesting that HSP70 is secreted by supporting cells. Together our data indicate that supporting cells mediate the protective effect of HSP70 against hair cell death, and they suggest a major role for supporting cells in determining the fate of hair cells exposed to stress.

Wild-type EGFR is stabilized by direct interaction with HSP90 in cancer cells and tumors.

The epidermal growth factor receptor (EGFR) has been targeted for inhibition using tyrosine kinase inhibitors and monoclonal antibodies, with improvement in outcome in subsets of patients with head and neck, lung, and colorectal carcinomas. We have previously found that EGFR stability plays a key role in cell survival after chemotherapy and radiotherapy. Heat shock protein 90 (HSP90) is known to stabilize mutant EGFR and ErbB2, but its role in cancers with wild-type (WT) WT-EGFR is unclear. In this report, we demonstrate that fully mature, membrane-bound WT-EGFR interacts with HSP90 independent of ErbB2. Further, the HSP90 inhibitors geldanamycin (GA) and AT13387 cause a decrease in WT-EGFR in cultured head and neck cancer cells. This decrease results from a significantly reduced half-life of WT-EGFR. WT-EGFR was also lost in head and neck xenograft specimens after treatment with AT13387 under conditions that inhibited tumor growth and prolonged survival of the mice. Our findings demonstrate that WT-EGFR is a client protein of HSP90 and that their interaction is critical for maintaining both the stability of the receptor as well as the growth of EGFR-dependent cancers. Furthermore, these findings support the search for specific agents that disrupt HSP90's ability to act as an EGFR chaperone.