Anatomical and functional organization of cardiac fibers in the porcine cervical vagus nerve allows spatially selective efferent neuromodulation.

Cardiac disease progression reflects the dynamic interaction between adversely remodeled neurohumoral control systems and an abnormal cardiac substrate. Vagal nerve stimulation (VNS) is an attractive neuromodulatory option to dampen this dynamic interaction; however, it is limited by off-target effects. Spatially-selective VNS (sVNS) offers a promising solution to induce cardioprotection while mitigating off-target effects by specifically targeting pre-ganglionic parasympathetic efferent cardiac fibers. This approach also has the potential to enhance therapeutic outcomes by eliminating time-consuming titration required for optimal VNS. Recent studies have demonstrated the independent modulation of breathing rate, heart rate, and laryngeal contraction through sVNS. However, the spatial organization of afferent and efferent cardiac-related fibers within the vagus nerve remains unexplored. By using trial-and-error sVNS in vivo in combination with ex vivo micro-computed tomography fascicle tracing, we show the significant spatial separation of cardiac afferent and efferent fibers (179±55° SD microCT, p<0.05 and 200±137° SD, p<0.05 sVNS - degrees of separation across a cross-section of nerve) at the mid-cervical level. We also show that cardiac afferent fibers are located in proximity to pulmonary fibers consistent with recent findings of cardiopulmonary convergent neurons and circuits. We demonstrate the ability of sVNS to selectively elicit desired scalable heart rate decrease without stimulating afferent-related reflexes. By elucidating the spatial organization of cardiac-related fibers within the vagus nerve, our findings pave the way for more targeted neuromodulation, thereby reducing off-target effects and eliminating the need for titration. This, in turn, will enhance the precision and efficacy of VNS therapy in treating cardiac pathology, allowing for improved therapeutic efficacy.

Organotopic organization of the porcine mid-cervical vagus nerve.

Introduction: Despite detailed characterization of fascicular organization of somatic nerves, the functional anatomy of fascicles evident in human and large mammal cervical vagus nerve is unknown. The vagus nerve is a prime target for intervention in the field of electroceuticals due to its extensive distribution to the heart, larynx, lungs, and abdominal viscera. However, current practice of the approved vagus nerve stimulation (VNS) technique is to stimulate the entire nerve. This produces indiscriminate stimulation of non-targeted effectors and undesired side effects. Selective neuromodulation is now a possibility with a spatially-selective vagal nerve cuff. However, this requires the knowledge of the fascicular organization at the level of cuff placement to inform selectivity of only the desired target organ or function. Methods and results: We imaged function over milliseconds with fast neural electrical impedance tomography and selective stimulation, and found consistent spatially separated regions within the nerve correlating with the three fascicular groups of interest, suggesting organotopy. This was independently verified with structural imaging by tracing anatomical connections from the end organ with microCT and the development of an anatomical map of the vagus nerve. This confirmed organotopic organization. Discussion: Here we show, for the first time, localized fascicles in the porcine cervical vagus nerve which map to cardiac, pulmonary and recurrent laryngeal function (N = 4). These findings pave the way for improved outcomes in VNS as unwanted side effects could be reduced by targeted selective stimulation of identified organ-specific fiber-containing fascicles and the extension of this technique clinically beyond the currently approved disorders to treat heart failure, chronic inflammatory disorders, and more.

Attenuation of Polysialic Acid Biosynthesis in Cells by the Small Molecule Inhibitor 8-Keto-sialic acid.

Sialic acids are key mediators of cell function, particularly with regard to cellular interactions with the surrounding environment. Reagents that modulate the display of specific sialyl glycoforms at the cell surface would be useful biochemical tools and potentially allow for therapeutic intervention in numerous challenging chronic diseases. While multiple strategies are being explored for the control of cell surface sialosides, none that shows high selectivity between sialyltransferases or that targets a specific sialyl glycoform has yet to emerge. Here, we describe a strategy to block the formation of α2,8-linked sialic acid chains (oligo- and polysialic acid) through the use of 8-keto-sialic acid as a chain-terminating metabolic inhibitor that, if incorporated, cannot be elongated. 8-Keto-sialic acid is nontoxic at effective concentrations and serves to block polysialic acid synthesis in cancer cell lines and primary immune cells, with minimal effects on other sialyl glycoforms.

O-glycosylation and its role in therapeutic proteins.

Protein glycosylation is ubiquitous throughout biology. From bacteria to humans, this post translational modification with sophisticated carbohydrate structures plays a profound role in the interaction of proteins with cells and changes the physiochemical properties of the proteins that carry them. When the glycans are linked to Ser or Thr residues, they are known as O-linked glycans, as the glycosidic linkage is through oxygen. O-glycans are perhaps best known as part of the mucin proteins, however many soluble proteins carry these types of glycans, and that their roles in biology are still being discovered. Many of the soluble proteins that carry O-glycans have a role as therapeutic proteins, and in the 21st century, the application of synthetic biology is starting to be applied to improving these proteins through manipulation of the glycans. This review will explore the role of these O-linked glycans in proteins with pharmaceutical significance, as well as recent advancements in recombinant glycoprotein therapeutics.

A previously uncharacterized O-glycopeptidase from Akkermansia muciniphila requires the Tn-antigen for cleavage of the peptide bond.

Akkermansia muciniphila is key member of the human gut microbiota that impacts many features of host health. A major characteristic of this bacterium is its interaction with host mucin, which is abundant in the gut environment, and its ability to metabolize mucin as a nutrient source. The machinery deployed by A. muciniphila to enable this interaction appears to be extensive and sophisticated, yet it is incompletely defined. The uncharacterized protein AMUC_1438 is encoded by a gene that was previously shown to be upregulated when the bacterium is grown on mucin. This uncharacterized protein has features suggestive of carbohydrate-recognition and peptidase activity, which led us to hypothesize that it has a role in mucin depolymerization. Here, we provide structural and functional support for the assignment of AMUC_1438 as a unique O-glycopeptidase with mucin-degrading capacity. O-glycopeptidase enzymes recognize glycans but hydrolyze the peptide backbone and are common in host-adapted microbes that colonize or invade mucus layers. Structural, kinetic, and mutagenic analyses point to a metzincin metalloprotease catalytic motif but with an active site that specifically recognizes a GalNAc residue α-linked to serine or threonine (i.e., the Tn-antigen). The enzyme catalyzes hydrolysis of the bond immediately N-terminal to the glycosylated residue. Additional modeling analyses suggest the presence of a carbohydrate-binding module that may assist in substrate recognition. We anticipate that these results will be fundamental to a wider understanding of the O-glycopeptidase class of enzymes and how they may contribute to host adaptation.

Front-Line Hospice Staff Perceptions of Barriers and Opportunities to Discussing Advance Care Planning With Hospice Patients and Their Families.

OBJECTIVES: To understand the facilitators and barriers to hospice staff engagement of patients and surrogates in advance care planning (ACP) conversations. DESIGN: Qualitative study conducted with purposive sampling and semistructured interviews using ATLAS.ti software to assist with template analysis. SETTINGS AND PARTICIPANTS: Participants included 51 hospice professionals (31 clinicians, 13 leaders, and 7 quality improvement administrators) from 4 geographically distinct nonprofit US hospices serving more than 2700 people. MEASURES: Interview domains were derived from the implementation science framework of Capability, Opportunity, Motivation, and Behavior (COM-B), with additional questions soliciting recommendations for behavior change. Differences in themes were reconciled by consensus. The facilitator, barrier, and recommendation themes were organized within the COM-B framework. RESULTS: Capability was facilitated by interdisciplinary teamwork and specified clinical staff roles and inhibited by lack of self-perceived skill in engaging in ACP conversations. Opportunities for ACP occurred during admission to hospice, acute changes, or deterioration in patient condition. Opportunity-related environmental barriers included time constraints such as short patient stay in hospice and workload expectations that prevented clinicians from spending more time with patients and families. Motivation to discuss ACP was facilitated by the employee's goal of providing personalized, patient-centered care. Implicit assumptions about patients' and families' preferences reduced staff's motivation to engage in ACP. Hospice staff made recommendations to improve ACP discussions, including training and modeling practice sessions, earlier introduction of ACP concepts by clinicians in prehospice settings, and increasing workforce diversity to reflect the patient populations the organizations want to reach and cultural competency. CONCLUSIONS AND IMPLICATIONS: Even hospice staff can be uncomfortable discussing death and dying. Yet staff were able to identify what worked well. Solutions to increase behavior of ACP engagement included staff training and modeling practice sessions, introducing ACP prior to hospice, and increasing workforce diversity to improve cultural competency.

An undergraduate medical curriculum framework for providing care to transgender and gender diverse patients: A modified Delphi study.

INTRODUCTION: The lack of attention to transgender and gender diverse (TGD) people in undergraduate medical education (UME) is a point of concern, particularly among medical students. A project was undertaken to develop a UME curriculum framework for teaching the healthcare needs of TGD people. METHODS: Using a modified Delphi methodology, four rounds of surveys were presented to an expert stakeholder group that included content experts, generalist physicians, UME teaching faculty, and medical students. Questions covered what content should be taught, who should teach the content, and how much time should be dedicated for this teaching. Once the Delphi process was complete, feedback on the provisional framework was sought from members of the TGD community to ensure it represented their needs and perspectives. RESULTS: 71 panel members and 56 community members participated in the study. Core values included the scope of the framework, and topics such as inclusivity, and safety in practice and in teaching. The framework included terminology, epidemiology, medical and surgical treatment, mental health, sexual and reproductive health, and routine primary care. There was also guidance on who should teach, time to be allocated, and the learning environment. DISCUSSION: There is a clear need to train tomorrow's doctors to provide competent and respectful healthcare services to and for TGD patients. Although local factors will likely shape the way in which this framework will be implemented in different contexts, this paper outlines a core UME-level curriculum framework for Canada and, potentially, for use in other parts of the world.

Mammalian sialyltransferases allow efficient Escherichia coli-based production of mucin-type O-glycoproteins but can also transfer Kdo.

The prospect of producing human-like glycoproteins in bacteria is becoming attractive as an alternative to already-established but costly mammalian cell expression systems. We previously described an Escherichia coli expression platform that uses a dual-plasmid approach to produce simple mucin type O-glycoproteins: one plasmid encoding the target protein and another O-glycosylation machinery. Here, we expand the capabilities of our platform to carry out sialylation and demonstrate the high-yielding production of human interferon α2b and human growth hormone bearing mono- and disialylated T-antigen glycans. This is achieved through engineering an E. coli strain to produce CMP-Neu5Ac and introducing various α-2,3- and α-2,6 mammalian or bacterial sialyltransferases into our O-glycosylation operons. We further demonstrate that mammalian sialyltransferases, including porcine ST3Gal1, human ST6GalNAc2 and human ST6GalNAc4, are very effective in vivo and outperform some of the bacterial sialyltransferases tested, including Campylobacter jejuni Cst-I and Cst-II. In the process, we came upon a way of modifying T-Antigen with Kdo, using a previously uncharacterised Kdo-transferase activity of porcine ST3Gal1. Ultimately, the heterologous expression of mammalian sialyltransferases in E. coli shows promise for the further development of bacterial systems in therapeutic glycoprotein production.

A Communication Perspective on What Patient Advisory Boards Do: Action-Implicative Discourse Analysis and Negotiating Advice.

Stakeholder advisory boards are recognized as an essential and useful part of patient-centered research. However, such engagement can involve exchanges of diverse individual experiences, multiple opinions, and strong feelings in the face of researchers' limitations, deadlines, and agendas. Yet, little work examines how these potential tensions occur and are resolved in actual advisory board meetings. This perspective article describes and employs a communication framework for analyzing a patient advisory council (PAC) for a comparative effectiveness study on acupuncture and pain counseling for inpatients with cancer. The framework, Action-Implicative Discourse Analysis (AIDA), is an observational method that examines challenges through recorded and transcribed, naturally occurring interaction. Our analysis focused on two short excerpts from the first PAC meeting to demonstrate members' navigation of advice-giving and advice-receiving-one in which advice was ultimately implemented by the study team and another in which it was deemed unfeasible. Although advice is inherent to the work of all PACs, it often emerges unannounced as negotiated moments, made up of seemingly minor conversation moves. As a recurring event, advice can and should be analyzed and discussed within PACs to improve communication and team dynamics.

Investigation of sequon engineering for improved O-glycosylation by the human polypeptide N-acetylgalactosaminyl transferase T2 isozyme and two orthologues.

We have been developing bacterial expression systems for human mucin-type O-glycosylation on therapeutic proteins, which is initiated by the addition of α-linked GalNAc to serine or threonine residues by enzymes in the GT-27 family of glycosyltransferases. Substrate preference across different isoforms of this enzyme is influenced by isoform-specific amino acid sequences at the site of glycosylation, which we have exploited to engineer production of Core 1 glycan structures in bacteria on human therapeutic proteins. Using RP-HPLC with a novel phenyl bonded phase to resolve intact protein glycoforms, the effect of sequon mutation on O-glycosylation initiation was examined through in vitro modification of the naturally O-glycosylated human interferon α-2b, and a sequon engineered human growth hormone. As part of the development of our glycan engineering in the bacterial expression system we are surveying various orthologues of critical enzymes to ensure complete glycosylation. Here we present an in vitro enzyme kinetic profile of three related GT-27 orthologues on natural and engineered sequons in recombinant human interferon α2b and human growth hormone where we show a significant change in kinetic properties with the amino acid changes. It was found that optimizing the protein substrate amino acid sequence using Isoform Specific O-Glycosylation Prediction (ISOGlyP, http://isoglyp.utep.edu/index.php) resulted in a measurable increase in kcat/KM, thus improving glycosylation efficiency. We showed that the Drosophila orthologue showed superior activity with our human growth hormone designed sequons compared with the human enzyme.

Selective Vagus Nerve Stimulation as a Therapeutic Approach for the Treatment of ARDS: A Rationale for Neuro-Immunomodulation in COVID-19 Disease.

Acute respiratory distress syndrome (ARDS) is the most severe form of acute lung injury. It is induced by sepsis, aspiration, and pneumonia, including that caused by SARS coronavirus and human influenza viruses. The main pathophysiological mechanism of ARDS is a systemic inflammatory response. Vagus nerve stimulation (VNS) can limit cytokine production in the spleen and thereby dampen any systemic inflammation and inflammation-induced tissue damage in the lungs and other organs. However, the effects of increased parasympathetic outflow to the lungs when non-selective VNS is applied may result in bronchoconstriction, increased mucus secretion and enhance local pulmonary inflammatory activity; this may outweigh the beneficial systemic anti-inflammatory action of VNS. Organ/function-specific therapy can be achieved by imaging of localized fascicle activity within the vagus nerve and selective stimulation of identified organ-specific fascicles. This may be able to provide selective neuromodulation of different pathways within the vagus nerve and offer a novel means to improve outcome in ARDS. This has motivated this review in which we discuss the mechanisms of anti-inflammatory effects of VNS, progress in selective VNS techniques, and a possible application for ARDS.

Barriers and facilitators to older adults' use of nonpharmacologic approaches for chronic pain: a person-focused model.

ABSTRACT: In the context of the opioid epidemic and the growing population of older adults living with chronic pain, clinicians are increasingly recommending nonpharmacologic approaches to patients as complements to or substitutes for pharmacologic treatments for pain. Currently, little is known about the factors that influence older adults' use of these approaches. We aimed to characterize the factors that hinder or support the use of nonpharmacologic approaches for pain management among older adults with multiple morbidities. We collected semistructured qualitative interview data from 25 older adults with multiple morbidities living with chronic pain for 6 months or more. Transcripts were coded to identify factors that hindered or supported participants' use of various nonpharmacologic approaches. We used the constant comparative method to develop a person-focused model of barriers and facilitators to participants' use of these approaches for chronic pain management. Participants described a wide range of factors that influenced their use of nonpharmacologic approaches. We grouped these factors into 3 person-focused domains: awareness of the nonpharmacologic approach as relevant to their chronic pain, appeal of the approach, and access to the approach. We propose and illustrate a conceptual model of barriers and facilitators to guide research and clinical care. This study identifies numerous factors that influence patients' use of nonpharmacologic approaches, some of which are not captured in existing research or routinely addressed in clinical practice. The person-centered model proposed may help to structure and support patient-clinician communication about nonpharmacologic approaches to chronic pain management.

Adaptations to Acupuncture and Pain Counseling Implementation in a Multisite Pragmatic Randomized Clinical Trial.

Objectives: As part of a pragmatic effectiveness trial of integrative pain management among inpatients with cancer, the authors sought to understand the clinical context and adaptations to implementation of two study interventions, acupuncture and pain counseling (i.e., pain education and coping skills). Design: The larger study uses a 2 × 2 factorial design with inpatients randomized to: (1) usual care (UC), (2) UC with acupuncture, (3) UC with pain counseling, and (4) UC with acupuncture and pain counseling. The study is being conducted in two hospitals (one academic and one public) and three languages (Cantonese, English, and Spanish). The authors conducted a process evaluation by interviewing study interventionists. Analysis included deductive coding to describe context, intervention, implementation, and inductive thematic coding related to intervention delivery. Results: Interviewees included seven acupuncturists and four pain counselors. Qualitative themes covered adaptations and recognizing site-specific differences that affected implementation. Interventionists adhered closely to protocols and made patient-centered adaptations that were then standardized in broader implementation (e.g., including caregivers in pain counseling sessions; working in culturally nuanced ways with non-English-speaking patients). The public hospital included more patients with recent diagnoses and advanced disease, more ethnically and linguistically diverse patients, less continuity of staffing, and shared patient rooms. At the academic medical center, more patients were familiar with integrative therapies and all were located in single rooms. Providing acupuncture to hospital staff was a key strategy to establish trust, experientially explain the intervention, and create camaraderie and staff buy-in. Conclusions: Providing nonpharmacologic interventions for a pragmatic trial requires adapting to a range of clinical factors. Site-specific factors included greater coordination and resources needed for successful implementation in the public hospital. The authors conclude that adaptation to context and individual patient needs can be done without compromising intervention fidelity and that intervention design should apply principles such as centering at the margins to reduce participation barriers for diverse patient populations.

Architecturally complex O-glycopeptidases are customized for mucin recognition and hydrolysis.

A challenge faced by peptidases is the recognition of highly diverse substrates. A feature of some peptidase families is the capacity to specifically use post-translationally added glycans present on their protein substrates as a recognition determinant. This is ultimately critical to enabling peptide bond hydrolysis. This class of enzyme is also frequently large and architecturally sophisticated. However, the molecular details underpinning glycan recognition by these O-glycopeptidases, the importance of these interactions, and the functional roles of their ancillary domains remain unclear. Here, using the Clostridium perfringens ZmpA, ZmpB, and ZmpC M60 peptidases as model proteins, we provide structural and functional insight into how these intricate proteins recognize glycans as part of catalytic and noncatalytic substrate recognition. Structural, kinetic, and mutagenic analyses support the key role of glycan recognition within the M60 domain catalytic site, though they point to ZmpA as an apparently inactive enzyme. Wider examination of the Zmp domain content reveals noncatalytic carbohydrate binding as a feature of these proteins. The complete three-dimensional structure of ZmpB provides rare insight into the overall molecular organization of a highly multimodular enzyme and reveals how the interplay of individual domain function may influence biological activity. O-glycopeptidases frequently occur in host-adapted microbes that inhabit or attack mucus layers. Therefore, we anticipate that these results will be fundamental to informing more detailed models of how the glycoproteins that are abundant in mucus are destroyed as part of pathogenic processes or liberated as energy sources during normal commensal lifestyles.

Fascicle localisation within peripheral nerves through evoked activity recordings: A comparison between electrical impedance tomography and multi-electrode arrays.

BACKGROUND: The lack of understanding of fascicular organisation in peripheral nerves limits the potential of vagus nerve stimulation therapy. Two promising methods may be employed to identify the functional anatomy of fascicles within the nerve: fast neural electrical impedance tomography (EIT), and penetrating multi-electrode arrays (MEA). These could provide a means to image the compound action potential within fascicles in the nerve. NEW METHOD: We compared the ability to localise fascicle activity between silicon shanks (SS) and carbon fibre (CF) multi-electrode arrays and fast neural EIT, with micro-computed tomography (MicroCT) as an independent reference. Fast neural EIT in peripheral nerves was only recently developed and MEA technology has been used only sparingly in nerves and not for source localisation. Assessment was performed in rat sciatic nerves while evoking neural activity in the tibial and peroneal fascicles. RESULTS: Recorded compound action potentials were larger with CF compared to SS (∼700 µV vs ∼300 µV); however, background noise was greater (6.3 µV vs 1.7 µV) leading to lower SNR. Maximum spatial discrimination between Centres-of-Mass of fascicular activity was achieved by fast neural EIT (402 ±â€¯30 µm) and CF MEA (414 ±â€¯123 µm), with no statistical difference between MicroCT (625 ±â€¯17 µm) and CF (p > 0.05) and between CF and EIT (p > 0.05). Compared to CF MEAs, SS MEAs had a lower discrimination power (103 ±â€¯51 µm, p < 0.05). COMPARISON WITH EXISTING METHODS: EIT and CF MEAs showed localisation power closest to MicroCT. Silicon MEAs adopted in this study failed to discriminate fascicle location. Re-design of probe geometry may improve results. CONCLUSIONS: Nerve EIT is an accurate tool for assessment of fascicular position within nerves. Accuracy of EIT and CF MEA is similar to the reference method. We give technical recommendations for performing multi-electrode recordings in nerves.

Development of BODIPY labelled sialic acids as sialyltransferase substrates for direct detection of terminal galactose on N- and O-linked glycans.

Glycans on proteins and cell surfaces are useful biomarkers for determining functional interactions with glycan binding proteins, potential disease states, or indeed level of differentiation. The ability to rapidly and sensitively detect or tag specific glycans on proteins provides a diagnostic tool with wide application in chemical glycobiology. The monosaccharide N-acetylneuraminic acid (sialic acid) is a key player in these interactions and the manipulation and control of sialylation levels has been an important research focus, particularly in the development of therapeutic proteins. Using sialyltransferases to tag specific glycans provides a rapid means of determining what types of glycans are present. We have synthesized two variants of sialic acid carrying the fluorophore BODIPY (4,4 -Difluoro-4-boro-3a,4a-diaza-s-indacene) and examined its use with several different sialyltransferases on a variety of protein substrates and cell surface glycans. Our data show that there are significant differences between various enzymes ability to transfer the labelled sialic acids, and that the type of N-glycan and target protein strongly influences this activity.

Ethical dilemmas in anesthesia mission trips.

PURPOSE OF REVIEW: Health inequities continue to exist globally especially when it comes to surgical and anesthesia services. Due to the lack of physician anesthesiologists in low- and middle-income countries, there has been an increase in the number of medical mission trips. Although these volunteers are attempting to fulfill a need they must be mindful and remember to adhere to ethical principles as they work collaboratively with host institutions. We will review the ethical dilemmas inherent in anesthesia mission trips. RECENT FINDINGS: Physician volunteers for medical missions may cause significant harm to patients and host communities if they do not work in tandem with host institutions. SUMMARY: Medical missions fulfill acute medical needs and have the opportunity to make a positive contribution to host communities by fulfilling local needs and supporting educational efforts for local providers.

Concurrent Use of Videolaryngoscope and Fiberoptic Bronchoscope in a Child with Neurofibromatosis to Facilitate Endotracheal Intubation.

INTRODUCTION: In children who have craniofacial asymmetry secondary to neurofibromatosis type 1, the securing of the airway can be challenging. These patients have varying degrees of head and neck tumors that complicate endotracheal intubation. Anesthesiologists have many techniques and devices that assist us in securing adult airways and these devices are available in pediatric sizes which can also be used to safely secure the smaller airways. CASE: This 13-year-old male patient with Neurofibromatosis presented with a 2 cm mouth opening, Mallampati IV assessment, and thyromental distance of 2 cm for surgery. During the previous management of this child's airway it was found to be difficult using the fiberoptic bronchoscope or the Glidescope alone. DISCUSSION: This is a case report of improvement of intubating conditions using both devices concurrently.