Team Consistency in Reducing Operative Time in Head and Neck Surgery with Microvascular Free Flap Reconstruction.

OBJECTIVE(S): To evaluate the impact of consistent surgical teams on procedure duration in head and neck free tissue transfer, and to evaluate the length of stay and readmission rates with consistent teams. METHODS: A retrospective chart review of head and neck microvascular reconstruction by a single surgeon between August 2017 and November 2021 was performed. Procedure duration, wound complications, length of stay, and 30-day readmissions were analyzed. One circulating nurse (CN) and surgical technologist (ST) were considered "consistent" due to their prior work with the primary surgeon. All others were considered "ad hoc." Teams were "Consistent CN + ST," "Consistent ST," "Consistent CN," or "Ad hoc." Procedure duration between groups was compared via analysis of variance. Multivariate linear regression was performed to predict procedure duration. RESULTS: A total of 135 patients were included. Age, sex, and American Society of Anesthesiologists status did not significantly differ across groups (p = 0.963; p = 0.467; p = 0.908, respectively). The mean procedure duration was 339.3 min and differed significantly across all groups (p = 0.006, Cohen d = 0.32). Compared to the Ad hoc group, consistent teams demonstrated significant reductions in mean procedure duration (Consistent CN + ST: 58.4 min, p = 0.001, Cohen d = 0.67; Consistent ST: 51.6 min, p = 0.013, Cohen d = 0.61; Consistent CN: 44.5 min, p = 0.031, Cohen d = 0.52). Controlling for other factors, the ad hoc team predicted increased procedure duration on multivariate analysis ( ß 57.38, 19.92-94.85, p < 0.003). Wound complications, length of stay, and readmission rates did not differ significantly across groups (p = 0.940; p = 0.174; p = 0.935, respectively). CONCLUSION: Consistent CN and ST improve operative efficiency in head and neck-free tissue transfer. Future studies may evaluate the impact of team consistency on complications, physician burnout, and health systems costs. LEVEL OF EVIDENCE: 3 Laryngoscope, 133:2154-2159, 2023.

Insights into Multilevel Resistive Switching in Monolayer MoS2.

The advent of two-dimensional materials has opened a plethora of opportunities in accessing ultrascaled device dimensions for future logic and memory applications. In this work, we demonstrate that a single layer of large-area chemical vapor deposition-grown molybdenum disulfide (MoS2) sandwiched between two metal electrodes can be tuned to show multilevel nonvolatile resistive memory states with resistance values separated by 5 orders of magnitude. The switching process is unipolar and thermochemically driven requiring significant Joule heating in the reset process. Temperature-dependent electrical measurements coupled with semiclassical charge transport models suggest that the transport in these devices varies significantly in the initial (pristine) state, high resistance state, and low resistance state. In the initial state, the transport is a one-step direct tunneling (at low voltage biases) and Fowler Nordeim tunneling (at higher bias) with an effective barrier height of 0.33 eV, which closely matches the Schottky barrier at the MoS2/Au interface. In the high resistive state, trap-assisted tunneling provides a reasonable fit to experimental data for a trap height of 0.82 eV. Density functional theory calculations suggest the possibility of single- and double-sulfur vacancies as the microscopic origins of these trap sites. The temperature-dependent behavior of the set and reset process are explained by invoking the probability of defect (sulfur vacancy) creation and mobility of sulfur ions. Finally, conductive atomic force microscopy measurements confirm that the multifilamentary resistive memory effects are inherent to a single-crystalline MoS2 triangle and not necessarily dependent on grain boundaries. The insights suggested in this work are envisioned to open up possibilities for ultrascaled, multistate, resistive memories for next-generation digital memory and neuromorphic applications.

Extended Low-Dose Exposure to Saxitoxin Inhibits Neurite Outgrowth in Model Neuronal Cells.

The potent neurotoxin saxitoxin (STX) belongs to a group of structurally related analogues produced by both marine and freshwater phytoplankton. The toxins act by blocking voltage-gated sodium channels stopping the inflow of sodium ions and the generation of action potentials. Exposure from marine sources occurs as a result of consuming shellfish which have concentrated the toxins, and freshwater exposure can occur from drinking water although there have been no acute poisonings from the latter source to date. Previously, the majority of research into this group of toxins, collectively known as the paralytic shellfish toxins, has focused on acute exposure resulting in paralytic shellfish poisoning. While acute exposure guidelines exist for both sources, there are no chronic exposure guidelines and there has been minimal research into this pattern of exposure despite the known role of electrical activity in neurogenesis. We aimed to investigate this pattern of exposure and its potential effects on neurodevelopment using model neuronal cells. PC12 and SH-SY5Y cells were exposed to STX (0.25-3 µg/l) for 7 days, after which time they were stained with TRITC-Phalloidin, to observe adverse morphological effects. Cells exposed to STX had a significant decrease (18-85%) in long axonlike projections, instead exhibiting a significant increase in shorter projections classified as filopodia (p < 0.05). The results suggest that extended low-dose exposure to STX can inhibit proper neurite outgrowth at concentrations well below guideline levels for both sources of exposure making it a potential public health concern.

Low dose extended exposure to saxitoxin and its potential neurodevelopmental effects: A review.

Saxitoxin (STX) and its analogs, the paralytic shellfish toxins (PSTs), are a group of potent neurotoxins well known for their role in acute paralytic poisoning by preventing the generation of action potentials in neuronal cells. They are found in both marine and freshwater environments globally and although acute exposure from the former has previously received more attention, low dose extended exposure from both sources is possible and to date has not been investigated. Given the known role of cellular electrical activity in neurodevelopment this pattern of exposure may be a significant public health concern. Additionally, the presence of PSTs is likely to be an ongoing and possibly increasing problem in the future. This review examines the neurodevelopmental toxicity of STX, the risk of extended or repeated exposure to doses with neurodevelopmental effects, the potential implications of this exposure and briefly, the steps taken and difficulties faced in preventing exposure.

An optimized method for obtaining adult rat spinal cord motor neurons to be used for tissue culture.

BACKGROUND: There is a paucity of detailed methods describing how to harvest and process motor neurons obtained from the adult rat spinal cord. NEW METHOD: Removal of intra-cardiac perfusion step. The spinal cord is extruded intact from the rat in under 60s post-decapitation then processed without differentiation of ventral and dorsal regions. The temperature during processing was maintained at room temperature (22°C) except during the Papain processing step where the temperature was increased to 30°C. RESULTS: Cell debris interfered with the counting of cells at the time of plating. Also, cell types could not be identified since they appear rounded structures with no projections. Cell viability counts reduced to 91% and 63% from day 7 to day 14 and days 7-28 respectively. Red blood cell counts in stepped density gradient layers 2 and 3 were low. COMPARISON WITH EXISTING METHOD(S): No requirement for intra-cardiac perfusion. No requirement to cool to 4°C post harvesting, No requirement for specialized substrates. Reduces processing time by at least 2h and reduces the potential for processing errors through a reduction in complexity. Procedures are also explained suitable for those new to the culture of primary adult motor neurons. CONCLUSIONS: Cell viability counts indicate that removal of the perfusion step has a minimal effect on the viability of the cultured nerve cells, which may be due to the reduction in the spinal cord harvesting time and the inclusion of Hibernate based media during extrusion and processing.

Standardising reporting of cervical lymphadenopathy in paediatric neck ultrasound: a pilot study using an evidence-based reporting protocol.

OBJECTIVES: Cervical lymphadenopathy is common in children and can arise from a wide range of aetiologies. Ultrasound can be a useful imaging tool for initial investigation but is known to be operator dependent. We aimed to compare the content of ultrasound reporting in this clinical scenario before and after the introduction of an evidence-based reporting protocol. METHODS: We performed a prospective 8-month pilot study assessing the content of ultrasound reports generated from scans to investigate suspected cervical lymphadenopathy in children referred to our tertiary referral otolaryngology service. We found wide variation in report content and inconsistent reporting of certain radiological features. In response to this we performed a literature search to identify key, clinically relevant ultrasonographic features for cervical lymphadenopathy and then in consultation with our radiology colleagues, devised a protocol to facilitate the reporting of these key features. Content of reports was then prospectively re-audited over a further 8-month period. RESULTS: 23 reports were assessed before and 26 after introduction of the reporting protocol. Fisher's exact test was used to analyse the data. We found a statistically significant (p < 0.05) improvement in the frequency of reporting of various key features such as nodal distribution, shape, echogenicity, calcification, necrosis and vascular pattern. CONCLUSIONS: The introduction of a standardised protocol has helped to streamline the reporting of ultrasounds to investigate cervical lymphadenopathy within our department. In the absence of any national guidelines on the reporting of paediatric neck ultrasound in this scenario, we propose that our protocol could be used by other departments to improve standardisation and as a teaching aid.

Coexpression of IL-5 and eotaxin-2 in mice creates an eosinophil-dependent model of respiratory inflammation with characteristics of severe asthma.

Mouse models of allergen provocation and/or transgenic gene expression have provided significant insights regarding the cellular, molecular, and immune responses linked to the pathologies occurring as a result of allergic respiratory inflammation. Nonetheless, the inability to replicate the eosinophil activities occurring in patients with asthma has limited their usefulness to understand the larger role(s) of eosinophils in disease pathologies. These limitations have led us to develop an allergen-naive double transgenic mouse model that expresses IL-5 systemically from mature T cells and eotaxin-2 locally from lung epithelial cells. We show that these mice develop several pulmonary pathologies representative of severe asthma, including structural remodeling events such as epithelial desquamation and mucus hypersecretion leading to airway obstruction, subepithelial fibrosis, airway smooth muscle hyperplasia, and pathophysiological changes exemplified by exacerbated methacholine-induced airway hyperresponsiveness. More importantly, and similar to human patients, the pulmonary pathologies observed are accompanied by extensive eosinophil degranulation. Genetic ablation of all eosinophils from this double transgenic model abolished the induced pulmonary pathologies, demonstrating that these pathologies are a consequence of one or more eosinophil effector functions.

Galphai2-mediated signaling events in the endothelium are involved in controlling leukocyte extravasation.

The trafficking of leukocytes from the blood to sites of inflammation is the cumulative result of receptor-ligand-mediated signaling events associated with the leukocytes themselves as well as with the underlying vascular endothelium. Our data show that Galpha(i) signaling pathways in the vascular endothelium regulate a critical step required for leukocyte diapedesis. In vivo studies using knockout mice demonstrated that a signaling event in a non-lymphohematopoietic compartment of the lung prevented the recruitment of proinflammatory leukocytes. Intravital microscopy showed that blockade was at the capillary endothelial surface and ex vivo studies of leukocyte trafficking demonstrated that a Galpha(i)-signaling event in endothelial cells was required for transmigration. Collectively, these data suggest that specific Galpha(i2)-mediated signaling between endothelial cells and leukocytes is required for the extravasation of leukocytes and for tissue-specific accumulation.

Pivotal Advance: eosinophil infiltration of solid tumors is an early and persistent inflammatory host response.

Tumor-associated eosinophilia has been observed in numerous human cancers and several tumor models in animals; however, the details surrounding this eosinophilia remain largely undefined and anecdotal. We used a B16-F10 melanoma cell injection model to demonstrate that eosinophil infiltration of tumors occurred from the earliest palpable stages with significant accumulations only in the necrotic and capsule regions. Furthermore, the presence of diffuse extracellular matrix staining for eosinophil major basic protein was restricted to the necrotic areas of tumors, indicating that eosinophil degranulation was limited to this region. Antibody-mediated depletion of CD4+ T cells and adoptive transfer of eosinophils suggested, respectively, that the accumulation of eosinophils is not associated with T helper cell type 2-dependent immune responses and that recruitment is a dynamic, ongoing process, occurring throughout tumor growth. Ex vivo migration studies have identified what appears to be a novel chemotactic factor(s) released by stressed/dying melanoma cells, suggesting that the accumulation of eosinophils in tumors occurs, in part, through a unique mechanism dependent on a signal(s) released from areas of necrosis. Collectively, these studies demonstrate that the infiltration of tumors by eosinophils is an early and persistent response that is spatial-restricted. It is more important that these data also show that the mechanism(s) that elicit this host response occur, independent of immune surveillance, suggesting that eosinophils are part of an early inflammatory reaction at the site of tumorigenesis.

Decreased size and survival of weanling mice in litters of IL-5-/ -mice are a consequence of the IL-5 deficiency in nursing dams.

We have observed decreased size and increased mortality rates in interleukin 5 (IL-5)-deficient mice versus IL-5-heterozygous and wild-type mice and have sought to define these differences. IL-5-deficient mice nursed by IL-5 deficient mothers were notably underweight, with a high percentage of preweaning mortality. In contrast, IL-5-deficient mice nursed by IL-5-sufficient foster mothers from birth were well-developed and robust at weaning, with a relatively low percentage of preweaning mortality. Mammary tissues from IL-5-deficient females at various landmark stages throughout life were prepared for microscopic assessment. When compared with mammary tissue from normal mice, that from IL-5-deficient dams appeared to have fewer terminal end buds, less well-developed branching of the mammary ducts, and lower overall density of mammary gland structures. The molecular and cellular bases for the differences in mammary gland development in IL-5-deficient mice relative to wild-type animals remains unknown. Under consideration are the roles that IL-5 and eosinophil granulocytes (the primary cell responsive to IL-5) may have in mammary gland development.

Defining a link with asthma in mice congenitally deficient in eosinophils.

Eosinophils are often dominant inflammatory cells present in the lungs of asthma patients. Nonetheless, the role of these leukocytes remains poorly understood. We have created a transgenic line of mice (PHIL) that are specifically devoid of eosinophils, but otherwise have a full complement of hematopoietically derived cells. Allergen challenge of PHIL mice demonstrated that eosinophils were required for pulmonary mucus accumulation and the airway hyperresponsiveness associated with asthma. The development of an eosinophil-less mouse now permits an unambiguous assessment of a number of human diseases that have been linked to this granulocyte, including allergic diseases, parasite infections, and tumorigenesis.

A causative relationship exists between eosinophils and the development of allergic pulmonary pathologies in the mouse.

Asthma and mouse models of allergic respiratory inflammation are invariably associated with a pulmonary eosinophilia; however, this association has remained correlative. In this report, a causative relationship between eosinophils and allergen-provoked pathologies was established using eosinophil adoptive transfer. Eosinophils were transferred directly into the lungs of either naive or OVA-treated IL-5(-/-) mice. This strategy resulted in a pulmonary eosinophilia equivalent to that observed in OVA-treated wild-type animals. A concomitant consequence of this eosinophil transfer was an increase in Th2 bronchoalveolar lavage cytokine levels and the restoration of intracellular epithelial mucus in OVA-treated IL-5(-/-) mice equivalent to OVA-treated wild-type levels. Moreover, the transfer also resulted in the development of airway hyperresponsiveness. These pulmonary changes did not occur when eosinophils were transferred into naive IL-5(-/-) mice, eliminating nonspecific consequences of the eosinophil transfer as a possible explanation. Significantly, administration of OVA-treated IL-5(-/-) mice with GK1.5 (anti-CD4) Abs abolished the increases in mucus accumulation and airway hyperresponsiveness following adoptive transfer of eosinophils. Thus, CD4(+) T cell-mediated inflammatory signals as well as signals derived from eosinophils are each necessary, yet alone insufficient, for the development of allergic pulmonary pathology. These data support an expanded view of T cell and eosinophil activities and suggest that eosinophil effector functions impinge directly on lung function.