Presbycusis and Hearing Preservation in Observed Vestibular Schwannomas

OBJECTIVE

We reviewed a cohort of patients with untreated sporadic vestibular schwannoma (VS) and examined the relationship between high-frequency hearing loss (HFHL) in the non-VS ear and long-term hearing outcomes in the VS-affected ear. We hypothesized that the progression of HFHL is associated with accelerated hearing decline in sporadic VS.

STUDY DESIGN

Retrospective cohort study.

SETTING

Tertiary center.

PATIENTS

We studied 102 patients with sporadic VS diagnosed from 1999 to 2015 with ≥5 years of observation (median, 6.92; interquartile range, 5.85-9.29). Sixty-six patients had AAO-HNS class A/B hearing at presentation and were included in analysis.

INTERVENTIONS

Audiometry, serial magnetic resonance imaging for observation of VS.

MAIN OUTCOME MEASURES

Four-frequency pure tone average (PTA) and word recognition scores (WRS) in the VS-affected ear. Decline in high-frequency PTA (average of thresholds at 4000, 6000, and 8,000 Hz) was defined as ≥10 dB during the study period. Decline in WRS was defined as ≥10%.

RESULTS

Compared with those without, patients with progressive HFHL in the non-VS ear were more likely to experience a decline in WRS in the VS ear (80% vs. 54%, p = 0.031). However, the same group showed no difference (52% vs. 41%, p = 0.40) in decline in PTA of the VS ear.

CONCLUSIONS

Patients with observed VS who experience progressive HFHL in the non-VS ear are more likely to experience significant declines in speech understanding in the VS-affected ear over time. Patients with a history of presbycusis may have an increased risk of losing serviceable hearing because of sporadic VS.

ASAS-NANP SYMPOSIUM: MATHEMATICAL MODELING IN ANIMAL NUTRITION: Opportunities and Challenges of Confined and Extensive Precision Livestock Production

Modern animal scientists, industry, and managers have never faced a more complex world. Precision livestock technologies have altered management in confined operations to meet production, environmental, and consumer goals. Applications of precision technologies have been limited in extensive systems such as rangelands due to lack of infrastructure, electrical power, communication, and durability. However, advancements in technology have helped to overcome many of these challenges. Investment in precision technologies is growing within the livestock sector, requiring the need to assess opportunities and challenges associated with implementation to enhance livestock production systems. In this review, precision livestock farming and digital livestock farming are explained in the context of a logical and iterative five-step process to successfully integrate precision livestock measurement and management tools, emphasizing the need for precision system models (PSMs). This five-step process acts as a guide to realize anticipated benefits from precision technologies and avoid unintended consequences. Consequently, the synthesis of precision livestock and modeling examples and key case studies help highlight past challenges and current opportunities within confined and extensive systems. Successfully developing PSM requires appropriate model(s) selection that aligns with desired management goals and precision technology capabilities. Therefore, it is imperative to consider the entire system to ensure that precision technology integration achieves desired goals while remaining economically and managerially sustainable. Achieving long-term success using precision technology requires the next generation of animal scientists to obtain additional skills to keep up with the rapid pace of technology innovation. Building workforce capacity and synergistic relationships between research, industry, and managers will be critical. As the process of precision technology adoption continues in more challenging and harsh, extensive systems, it is likely that confined operations will benefit from required advances in precision technology and PSMs, ultimately strengthening the benefits from precision technology to achieve short- and long-term goals.

First Report of the Bat Tick Carios kelleyi (Acari: Ixodida: Argasidae) From Vermont, United States

The soft tick Carios kelleyi (Cooley and Kohls, 1941) is an ectoparasite of bats that can harbor bacteria known to cause disease in humans, such as Rickettsia spp., Bartonella spp., and relapsing fever Borrelia spp. Human-tick encounters may occur when bats occupy attics or similar dwellings with access points to human-inhabited areas. During May 2021, a partially engorged adult female C. kelleyi was collected from a Vermont home with an attic that was being used as a roost by big brown bats, Eptesicus fuscus (Chiroptera: Vespertilionidae). The source of the blood in the tick was the domestic dog, Canis lupus familiaris. Subsequently, eight C. kelleyi larvae were collected from a rescued E. fuscus adult. This is the first report of a soft tick species from Vermont and it is unknown how long C. kelleyi has been present in this state. Reports of C. kelleyi are on the rise across the northeastern United States but the implications for the health of humans, domestic animals, and bats in northern New England remain unclear. Bat management plans should consider the importance of bat exclusion in preventing tick encounters with members of the household and should include a tick monitoring component if bats are evicted.

Comparative hologenomics of two Ixodes scapularis tick populations in New Jersey

Tick-borne diseases, such as those transmitted by the blacklegged tick Ixodes scapularis, are a significant and growing public health problem in the US. There is mounting evidence that co-occurring non-pathogenic microbes can also impact tick-borne disease transmission. Shotgun metagenome sequencing enables sampling of the complete tick hologenome—the collective genomes of the tick and all of the microbial species contained therein, whether pathogenic, commensal or symbiotic. This approach simultaneously uncovers taxonomic composition and allows the detection of intraspecific genetic variation, making it a useful tool to compare spatial differences across tick populations. We evaluated this approach by comparing hologenome data from two tick samples (N = 6 ticks per location) collected at a relatively fine spatial scale, approximately 23 km apart, within a single US county. Several intriguing variants in the data between the two sites were detected, including polymorphisms in both in the tick’s own mitochondrial DNA and that of a rickettsial endosymbiont. The two samples were broadly similar in terms of the microbial species present, including multiple known tick-borne pathogens (Borrelia burgdorferi, Babesia microti, and Anaplasma phagocytophilum), filarial nematodes, and Wolbachia and Babesia species. We assembled the complete genome of the rickettsial endosymbiont (most likely Rickettsia buchneri) from both populations. Our results provide further evidence for the use of shotgun metagenome sequencing as a tool to compare tick hologenomes and differentiate tick populations across localized spatial scales.

Preclinical assessment of clinically streamlined, 3D-printed, biocompatible single- and two-stage tissue scaffolds for ear reconstruction

Auricular reconstruction is a technically demanding procedure requiring significant surgical expertise, as the current gold standard involves hand carving of the costal cartilage into an auricular framework and re-implantation of the tissue. 3D-printing presents a powerful tool that can reduce technical demands associated with the procedure. Our group compared clinical, radiological, histological, and biomechanical outcomes in single- and two-stage 3D-printed auricular tissue scaffolds in an athymic rodent model. Briefly, an external anatomic envelope of a human auricle was created using DICOM computed tomography (CT) images and modified in design to create a two-stage, lock-in-key base and elevating platform. Single- and two-stage scaffolds were 3D-printed by laser sintering poly-L-caprolactone (PCL) then implanted subcutaneously in five athymic rats each. Rats were monitored for ulcer formation, site infection, and scaffold distortion weekly, and scaffolds were explanted at 8 weeks with analysis using microCT and histologic staining. Nonlinear finite element analysis was performed to determine areas of high strain in relation to ulcer formation. Scaffolds demonstrated precise anatomic appearance and maintenance of integrity of both anterior and posterior auricular surfaces and scaffold projection, with no statistically significant differences in complications noted between the single- and two-staged implantation. While minor superficial ulcers occurred most commonly at the lateral and superior helix coincident with finite element predictions of high skin strains, evidence of robust tissue ingrowth and angiogenesis was visible grossly and histologically. This promising preclinical small animal model supports future initiatives for making clinically viable options for an ear tissue scaffold.

Functional outcomes and tracheostomy dependence following salvage oropharyngeal surgery

Purpose:

Salvage surgical treatment of oropharyngeal cancer is associated with significant morbidity. We aim to identify predictive factors of functional outcomes to improve patient selection and counseling when contemplating salvage oropharyngectomy.

Methods:

Patients with a history of radiation requiring salvage oropharyngeal surgery were identified. Primary outcomes were determined at one year post-salvage surgery and included Gastric tube (G-tube) dependence, dietary restrictions, tracheostomy dependence, and speech intelligibility. Multivariate analyses were performed to identify predictors of the primary outcomes.

Results:

At one year, 45% (22/49) of patients had a G-tube, 68% (33/48) had dietary restrictions, 10% (5/49) remained tracheostomy dependent, and 15% (4/26) had difficulty with speech intelligibility. On univariate analysis, pre-operative G-tube (83% vs. 40%, p=0.04), reconstruction with a free flap (54% vs. 0%, p=0.005), and bony resection (69% vs. 36%, p=0.04) were significantly associated with G-tube dependence at one year. On multivariate analysis, concurrent bony resection remained a significant predictor of G-tube dependence (HR 5.4, 95% CI 1.2–24, p=0.03). Predictors of dietary restriction included free-flap reconstruction (78% vs. 25%, HR 0.13, 95% CI 0.02–0.87, p=0.04) and recurrence after two years (85% vs. 48%, HR 4.9, 95% CI 1.2–21, p=0.03). Supraglottic laryngectomy was significantly associated with tracheostomy dependence on univariate (67% vs. 7%, p=0.001) and multivariate analysis (HR 44.4, 95% CI 2.0–986, p=0.02).

Conclusion and Relevance:

Functional outcomes are suboptimal after salvage oropharyngectomy. Specific patient and disease factors are independently associated with worse speech and swallowing outcomes and may aid in pre-operative patient selection, risk stratification, and shared decision-making.

Intraoperative Fluorescent Angiography Predicts Pharyngocutaneous Fistula After Salvage Laryngectomy

BACKGROUND

Technology to assess tissue perfusion is exciting with translational potential, although data supporting its clinical applications have been lagging. Patients who have undergone radiation are at particular risk of poor tissue perfusion and would benefit from this expanding technology. We designed a prospective clinical trial using intraoperative indocyanine green angiography to evaluate for wound-healing complications in patients undergoing salvage laryngectomy after radiation failure.

PATIENTS AND METHODS

This prospective trial included patients undergoing salvage laryngectomy at a National Cancer Institute-designated tertiary cancer center between 2016 and 2018. After tumor extirpation and prior to reconstruction, 10 mg indocyanine green dye was infused and the fluorescence (F_HYPO) and ingress rate of the pharyngeal mucosa recorded. The primary outcome measure was formation of a pharyngocutaneous fistula (PCF).

RESULTS

Patients who developed a PCF had significantly lower F_HYPO (87 vs 172, p < 0.001) and ingress rates (6.7 vs 15.8, p = 0.043) compared with those who did not develop a fistula. There were no fistulas in patients with F_HYPO > 150 (n = 21) or ingress > 15 (n = 15). There was a 50% fistula rate in patients with F_HYPO ≤ 103 (n = 10) and ingress rate ≤ 6 (n = 6).

CONCLUSIONS

Intraoperative indocyanine green angiography can assess hypoperfusion in patients and predict risk of PCFs after salvage laryngectomy, and can thus intraoperatively risk-stratify patients for postoperative wound-healing complications.

Head and Neck Squamous Cell Carcinoma Detection and Surveillance: Advances of Liquid Biomarkers

Head and neck squamous cell carcinomas are aggressive tumors that often present at advanced stage in difficult-to-biopsy regions of the head and neck. With the rapid move to analyze circulating tumor DNA (ctDNA) to either detect cancer or monitor disease progression and response to therapy, we have designed this article as a primer to understand the recent studies that support a transition to use these circulating biomarkers as a part of routine clinical care. Whereas some technical challenges still need to be overcome, the utility of ctDNA in cancer care is already evident from these early studies. Therefore, it is critical to understand recent advances in this area as well as emerging questions that need to be addressed as these biomarkers move closer to enhancing routine clinical care paradigms. Laryngoscope, 129:1836-1843, 2019.

Pore architecture effects on chondrogenic potential of patient-specific 3-dimensionally printed porous tissue bioscaffolds for auricular tissue engineering

OBJECTIVE

This study aims to determine the effect of auricular scaffold microarchitecture on chondrogenic potential in an in vivo animal model.

METHODS

DICOM computed tomography (CT) images of a human auricle were segmented to create an external anatomic envelope. Image-based design was used to generate 1) orthogonally interconnected spherical pores and 2) randomly interspersed pores, and each were repeated in three dimensions to fill the external auricular envelope. These auricular scaffolds were then 3D printed by laser sintering poly-l-caprolactone, seeded with primary porcine auricular chondrocytes in a hyaluronic acid/collagen hydrogel and cultured in a pro-chondrogenic medium. The auricular scaffolds were then implanted subcutaneously in rats and explanted after 4 weeks for analysis with Safranin O and Hematoxylin and Eosin staining.

RESULTS

Auricular constructs with two micropore architectures were rapidly manufactured with high fidelity anatomic appearance. Subcutaneous implantation of the scaffolds resulted in excellent external appearance of both anterior and posterior auricular surfaces. Analysis on explantation showed that the defined, spherical micropore architecture yielded histologic evidence of more robust chondrogenic tissue formation as demonstrated by Safranin O and Hematoxylin and Eosin staining.

CONCLUSIONS

Image-based computer-aided design and 3D printing offers an exciting new avenue for the tissue-engineered auricle. In early pilot work, creation of spherical micropores within the scaffold architecture appears to impart greater chondrogenicity of the bioscaffold. This advantage could be related to differences in permeability allowing greater cell migration and nutrient flow, differences in surface area allowing different cell aggregation, or a combination of both factors. The ability to design an anatomically correct scaffold that maintains its structural integrity while also promoting auricular cartilage growth represents an important step towards clinical applicability of this new technology.

REV1 and polymerase ζ facilitate homologous recombination repair

REV1 and DNA Polymerase ζ (REV3 and REV7) play important roles in translesion DNA synthesis (TLS) in which DNA replication bypasses blocking lesions. REV1 and Polζ have also been implicated in promoting repair of DNA double-stranded breaks (DSBs). However, the mechanism by which these two TLS polymerases increase tolerance to DSBs is poorly understood. Here we demonstrate that full-length human REV1, REV3 and REV7 interact in vivo (as determined by co-immunoprecipitation studies) and together, promote homologous recombination repair. Cells lacking REV3 were hypersensitive to agents that cause DSBs including the PARP inhibitor, olaparib. REV1, REV3 or REV7-depleted cells displayed increased chromosomal aberrations, residual DSBs and sites of HR repair following exposure to ionizing radiation. Notably, cells depleted of DNA polymerase η (Polη) or the E3 ubiquitin ligase RAD18 were proficient in DSB repair following exposure to IR indicating that Polη-dependent lesion bypass or RAD18-dependent monoubiquitination of PCNA are not necessary to promote REV1 and Polζ-dependent DNA repair. Thus, the REV1/Polζ complex maintains genomic stability by directly participating in DSB repair in addition to the canonical TLS pathway.

Prolonged insulin resistance following insulin-induced hypoglycaemia

Nineteen normal male volunteers underwent a 10-h glucose clamp study to examine the duration and mechanism of insulin resistance after hypoglycaemia. Dextrose delivery by the Biostator to maintain the target blood glucose level fell below baseline 2 h after induction of hypoglycaemia and remained suppressed for at least 7 h after insulin hypoglycaemia. Insulin secretion as manifested by C-peptide levels remained suppressed for 3-4 h after insulin hypoglycaemia despite return of blood glucose to baseline by 90 min. Glucose kinetic data (3-3H-glucose) performed in six of the subjects indicated that the prolonged insulin resistance was due to significantly increased hepatic glucose production and to suppressed glucose utilisation, persisting for at least 4 h after counterregulatory hormone levels had returned to normal. Post-hypoglycaemic insulin resistance as determined by dextrose delivery was markedly attenuated and the rise in hepatic glucose output totally eliminated in five hypopituitary subjects without growth hormone or cortisol responses to hypoglycaemia. We conclude that post-hypoglycaemic insulin resistance occurs in non-diabetic subjects and persists for at least 7 h following hypoglycaemia. This prolonged insulin resistance is largely related to release of growth hormone and cortisol.

Pump-induced insulin aggregation. A problem with the Biostator

A fall in plasma IRI despite constant C-peptide levels during prolonged insulin euglycemic clamp studies using the Biostator (Ames Division, Miles Laboratories, Elkhart, Indiana) prompted a meticulous evaluation of the Biostator's insulin delivery system. At slow infusion rates, a striking loss of immunoreactive and biologically active insulin was observed after 6 h of the Biostator run. Studies with labeled insulin indicated that the loss of insulin was not due to adsorption of insulin to the tubing since recovery of labeled insulin was close to 100%. A variety of techniques (gel filtration, polyacrylamide gel electrophoresis, centrifugation, and Coomassie Brilliant Blue protein assay) indicated that the loss of insulin activity was due to insulin coming out of solution. The insoluble nature of the immunologically and biologically inactive insulin was confirmed by centrifugation, i.e., 88% 125I-insulin precipitated into the pellet. The dependency of this loss of insulin activity on flow rate was clearly demonstrable with activity (IRI) less than 20% of expected at flow rates of 2.1 ml/h, and 30% at 4.2 ml/h. Full recovery was observed only with flow rates of 16.8 ml/h or greater. At each flow rate, IRI rose only after delivery of the effluent between the pump and exit port, demonstrating that insulin alteration occurs within the pump assembly presumably from heat-induced aggregation. Investigators employing the Biostator should carefully examine their systems for this time- and flow rate-dependent alteration of insulin. The loss of IRI at low flow rates (low-dose insulin clamp or insulin delivery during basal periods) will profoundly influence data generated from the Biostator.