Cochlear implant material effects on inflammatory cell function and foreign body response.

OBJECTIVES: The objectives of this study were to assess the effects of cochlear implant (CI) biomaterials on the function of macrophages and fibroblasts, two key mediators of the foreign body response (FBR) and to determine how these materials influence fibrous tissue growth and new bone formation within the cochlea. METHODS: Macrophages and fibroblasts were cultured on polydimethylsiloxane (PDMS) and platinum substrates and human CI electrodes in vitro. Cell count, cell proliferation, cytokine production, and cell adhesion were measured. CI electrodes were implanted into murine cochleae for three weeks without electrical stimulation. Implanted cochleae were harvested for 3D X-ray microscopy with the CI left in-situ. The location of new bone growth within the scala tympani (ST) with reference to different portions of the implant (PDMS vs platinum) was quantified. RESULTS: Cell counts of macrophages and fibroblasts were significantly higher on platinum substrates and platinum contacts of CI electrodes. Fibroblast proliferation was greater on platinum relative to PDMS, and cells grown on platinum formed more/larger focal adhesions. 3D X-ray microscopy showed neo-ossification in the peri­implant areas of the ST. Volumetric quantification of neo-ossification showed a trend toward greater bone formation adjacent to the platinum electrodes compared to areas opposite or away from the platinum electrode bearing surfaces. CONCLUSIONS: Fibrotic reactions are biomaterial specific, as demonstrated by the differences in cell adhesion, proliferation, and fibrosis on platinum and PDMS. The inflammatory reaction to platinum contacts on CI electrodes likely contributes to fibrosis to a greater degree than PDMS, and platinum contacts may influence the deposition of new bone, as demonstrated in the in vivo data. This information can potentially be used to influence the design of future generations of neural prostheses.

Nutritional Concerns among Female International Volunteers Based on the Income and Development Status of Their Country of Service.

This study aimed to determine the prevalence of female athlete triad risk factors among female international volunteers based on the development and income status of their country of service. A total of 2164 past volunteers completed a retrospective survey. Countries' income and development statuses were coded using the respective annual United Nations World Economic Situations and Prospects reports. Independent t-tests, ANOVAs, and Pearson's Chi-Squared tests were used to assess group differences; corresponding odds ratios were calculated. Volunteers in nondeveloped (OR = 2.25, CI = 1.85-2.75) and non-high-income (OR = 2.17, CI = 1.75-2.70) countries had over twice the odds of experiencing secondary amenorrhea. More volunteers who served in nondeveloped countries reported an increase in exercise while serving (p = 0.005). Those who served in a nondeveloped (OR = 1.52, CI = 1.16-1.98) or non-high-income (OR = 1.45, CI = 1.08-1.94) country had higher odds of weight loss. However, volunteers serving in nondeveloped (OR = 0.52, CI = 0.44-0.63) and non-high-income (OR = 0.50, CI = 0.4-0.61) countries were less likely to report food insecurity compared to those in developed and high-income countries. Bone mineral density was within the expected range regardless of income and development status. Female volunteers who served in nondeveloped and non-high-income countries experienced higher odds of secondary amenorrhea, which was likely influenced by an increase in exercise and higher odds of weight loss.

Endocrine surgeons have high rates of work-related musculoskeletal (MSK) injury and symptoms.

BACKGROUND: Work-related injury and musculoskeletal (MSK) symptoms are common among surgeons, however data for endocrine surgeons (ES) are lacking. METHODS: A survey was distributed to American Association of Endocrine Surgeons (AAES) and Endocrine section of American Head and Neck Society (AHNS) members. RESULTS: MSK symptoms were present in 199 (90%) of 220 respondents, most notably pain (91%) and stiffness (81%). The most common locations were neck (87%) and shoulders (55%). Women were more likely to be symptomatic (98.6% versus 86.4%, p = 0.004). Although 67% of respondents reported awareness of ergonomic principles, only 19% had learned about them during training. The most common ergonomic adjustments were stretching, use of microbreaks and headlight/loupe adjustments. CONCLUSION: The vast majority of ES surgeons suffer MSK symptoms that could potentially impact their quality of life and career length. Effective strategies are needed to protect this highly trained workforce.

Timing of Acoustic Hearing Changes After Cochlear Implantation.

OBJECTIVES/HYPOTHESIS: To determine the timing of acoustic hearing changes among hearing preservation Cochlear implant (CI) recipients. To determine differences in hearing outcomes based on device type and demographic factors. To determine if there is a relationship between the extent of early hearing loss after CI and the subsequent rate of continued hearing loss. STUDY DESIGN: Prospective, single subject study. METHODS: Two hundred and eleven subjects who received a hearing preservation CI were included in the study-80 Nucleus Hybrid L24 (Cochlear), 47 422/522 (Cochlear), 24 S8 (Cochlear), 14 S12 (Cochlear), 6 SRW (Cochlear), 21 SLIM J (Advanced Bionics), and 19 Flex (Med-EL). Of these, 127 were included in the subsequent analyses. Audiometric thresholds (low frequency pure-tone-averages) were collected and compared pre and postoperatively. RESULTS: Long-term hearing preservation rates were 65% (52/80) for L24, 83% (20/24) for S8, 79% (11/14) for S12, 83% (5/6) for SRW, 54% (25/47) for 422/522, 91% (21/23) for SLIM J, and 84% (16/19) for Flex. Hearing loss was not related to device type (P = .9105) or gender (P = .2169). Older subjects (age ≥65) had worse hearing outcomes than younger subjects after initial device activation (age <65, P = .0262). There was no significant difference in rate of hearing loss over time between older and younger patients (P = .0938). Initial postoperative hearing loss was not associated with the rate of long-term hearing loss. CONCLUSIONS: Long-term low frequency hearing preservation is possible for CI recipients and is not associated with gender or device type. Rate of hearing loss over time is not dependent on patient age. Early hearing loss after CI does not predict the rate of long-term hearing loss. LEVEL OF EVIDENCE: 3 Laryngoscope, 132:2036-2043, 2022.

Antifouling and Mechanical Properties of Photografted Zwitterionic Hydrogel Thin-Film Coatings Depend on the Cross-Link Density.

Zwitterionic polymer networks have shown promise in reducing the short- and long-term inflammatory foreign body response to implanted biomaterials by combining the antifouling properties of zwitterionic polymers with the mechanical stability provided by cross-linking. Cross-link density directly modulates mechanical properties (i.e., swelling behavior, resistance to stress and strain, and lubricity) but theoretically could reduce desirable biological properties (i.e., antifouling) of zwitterionic materials. This work examined the effect of varying poly(ethylene glycol) dimethacrylate cross-linker concentration on protein adsorption, cell adhesion, equilibrium swelling, compressive modulus, and lubricity of zwitterionic thin films. Furthermore, this work aimed to determine the appropriate balance among each of these mechanical and biologic properties to produce thin films that are strong, durable, and lubricious, yet also able to resist biofouling. The results demonstrated nearly a 20-fold reduction in fibrinogen adsorption on zwitterionic thin films photografted on polydimethylsiloxane (PDMS) across a wide range of cross-link densities. Interestingly, either at high or low cross-link densities, increased levels of protein adsorption were observed. In addition to fibrinogen, macrophage and fibroblast cell adhesion was reduced significantly on zwitterionic thin films, with a large range of cross-link densities, resulting in low cell counts. The macrophage count was reduced by 30-fold, while the fibroblast count was reduced nearly 10-fold on grafted zwitterionic films relative to uncoated films. Increasing degrees of cell adhesion were noted as the cross-linker concentration exceeded 50%. As expected, increased cross-link density resulted in a reduced swelling but greater compressive modulus. Notably, the coefficient of friction was dramatically reduced for zwitterionic thin films compared to uncoated PDMS across a broad range of cross-link densities, an attractive property for insertional implants. This work identified a broad range of cross-link densities that provide desirable antifouling effects while also maintaining the mechanical functionality of the thin films.

Incorporating Surgical Ergonomics Education into Surgical Residency Curriculum.

BACKGROUND: Education on surgical ergonomics during residency training is lacking. This study aimed to determine the feasibility and impact of incorporating surgical ergonomics lectures into residency curriculum. METHODS: A survey was distributed to 42 residents with questions regarding demographics, surgical factors, prevalence of musculoskeletal (MSK) symptoms, and awareness of ergonomic recommendations. The residents then received 2 lectures on ergonomics in surgery. A follow up survey was distributed to evaluate the impact of the lectures. RESULTS: Twenty-two residents completed the presession survey. Ninety-one percent reported MSK symptoms attributed to their training. Seventeen residents completed the follow up survey. All reported increased awareness of their own habits while operating and improved understanding of methods to prevent and/or treat work-related injuries. All residents recommended incorporating the lectures as an adjunct to their regular curriculum. CONCLUSIONS: The rates of MSK symptoms and/or injury are high among surgeon trainees. Residency is an opportune time to educate on principles of ergonomics and may prevent future injuries.