Clonal Deletion Prunes but Does Not Eliminate Self-Specific αß CD8(+) T Lymphocytes.

It has long been thought that clonal deletion efficiently removes almost all self-specific T cells from the peripheral repertoire. We found that self-peptide MHC-specific CD8(+) T cells in the blood of healthy humans were present in frequencies similar to those specific for non-self antigens. For the Y chromosome-encoded SMCY antigen, self-specific T cells exhibited only a 3-fold lower average frequency in males versus females and were anergic with respect to peptide activation, although this inhibition could be overcome by a stronger stimulus. We conclude that clonal deletion prunes but does not eliminate self-specific T cells and suggest that to do so would create holes in the repertoire that pathogens could readily exploit. In support of this hypothesis, we detected T cells specific for all 20 amino acid variants at the p5 position of a hepatitis C virus epitope in a random group of blood donors.

Incidence of airway complications associated with deep extubation in adults.

BACKGROUND: Endotracheal extubation is the most crucial step during emergence from general anesthesia and is usually carried out when patients are awake with return of airway reflexes. Alternatively, extubations can also be accomplished while patients are deeply anesthetized, a technique known as "deep extubation", in order to provide a "smooth" emergence from anesthesia. Deep extubation is seldomly performed in adults, even in appropriate circumstances, likely due to concerns for potential respiratory complications and limited research supporting its safety. It is in this context that we designed our prospective study to understand the factors that contribute to the success or failure of deep extubation in adults. METHODS: In this prospective observational study, 300 patients, age ≥ 18, American Society of Anesthesiologists Physical Status (ASA PS) Classification I - III, who underwent head-and-neck and ocular surgeries. Patients' demographic, comorbidity, airway assessment, O2 saturation, end tidal CO2 levels, time to exit OR, time to eye opening, and respiratory complications after deep extubation in the OR were analyzed. RESULTS: Forty (13%) out of 300 patients had at least one complication in the OR, as defined by persistent coughing, desaturation SpO2 < 90% for longer than 10s, laryngospasm, stridor, bronchospasm and reintubation. When comparing the complication group to the no complication group, the patients in the complication group had significantly higher BMI (30 vs 26), lower O2 saturation pre and post extubation, and longer time from end of surgery to out of OR (p < 0.05). CONCLUSIONS: The complication rate during deep extubation in adults was relatively low compared to published reports in the literature and all easily reversible. BMI is possibly an important determinant in the success of deep extubation.

Choice of Anesthesia for Cesarean Delivery: An Analysis of the National Anesthesia Clinical Outcomes Registry.

Neuraxial anesthesia use in cesarean deliveries (CDs) has been rising since the 1980s, whereas general anesthesia (GA) use has been declining. In this brief report we analyzed recent obstetric anesthesia practice patterns using National Anesthesiology Clinical Outcomes Registry data. Approximately 218,285 CD cases were identified between 2010 and 2015. GA was used in 5.8% of all CDs and 14.6% of emergent CDs. Higher rates of GA use were observed in CDs performed in university hospitals, after hours and on weekends, and on patients who were American Society of Anesthesiologists class III or higher and 18 years of age or younger.

Retrospective Analysis of Perioperative Dexmedetomidine Use in Retina Surgeries: Impact on Postanesthesia Care.

BACKGROUND AND OBJECTIVE: Dexmedetomidine (Precedex®) has been linked to depressive hemodynamic effects and increased length of stay in the post-anesthesia care unit (PACU) when used in ambulatory phacoemulsification procedures. We aimed to determine the prevalence and impact of dexmedetomidine use during ambulatory vitreoretinal procedures. PATIENTS AND METHODS: This retrospective cohort study involved 9,666 adult vitrectomies. Cases were divided into groups by anesthesia type: general anesthesia (GA) and monitored anesthesia care (MAC). For each group, various factors were compared between those who did and did not receive dexmedetomidine. Chi-squared and t tests were used for comparisons. RESULTS: Changes in mean arterial pressure in the MAC group were -1.69 ± 0.23 mmHg for no dexmedetomidine patients and -6.31 ± 0.39 mmHg for dexmedetomidine patients (P < 0.01). In the GA group, mean arterial pressure was -6.1 ± 0.35 mmHg for no dexmedetomidine patients and -11.18 ± 0.88 mmHg for dexmedetomidine patients (P < 0.01). PACU Phase II time in the MAC group was 36.93 ± 0.37 minutes and 40.67 ± 0.86 minutes for no dexmedetomidine and dexmedetomidine patients, respectively (P < 0.01). In the GA group, PACU Phase II time was 58.63 ± 0.95 minutes and 65.19 ± 2.38 minutes for no dexmedetomidine and dexmedetomidine patients, respectively (P < 0.01). CONCLUSIONS: Dexmedetomidine use in vitrectomies was associated with significant PACU delays. These delays may stem from adverse hemodynamic effects. [Ophthalmic Surg Lasers Imaging Retina 2024;55:86-91.].

Postoperative and postdischarge nausea and vomiting following ambulatory eye, head, and neck surgeries: a retrospective cohort study comparing incidence and associated factors.

BACKGROUND: Ambulatory surgery is often followed by the development of nausea and/or vomiting (N/V). Although risk factors for postoperative nausea and vomiting (PONV) are frequently discussed, the distinction between PONV and postdischarge nausea and vomiting (PDNV) is unclear. This is especially troublesome given the potential consequences of postdischarge nausea and vomiting (PDNV), which include major discomfort and hospital readmission. METHODS: In this retrospective cohort study, data from 10,231 adult patients undergoing ambulatory ophthalmology or otolaryngology procedures with general anesthesia were collected and analyzed. Binary and multinomial logistic regression was used to assess the association between patient and anesthetic characteristics (including age, body mass index (BMI), American Society of Anesthesiologists Physical Status (ASA P/S) classification, current smoker status, and intra- and postoperative opioid usage) and the odds ratios of experiencing only PDNV, only PONV, or both PONV and PDNV, as compared to not experiencing N/V at all. RESULTS: We found that 17.8% of all patients developed N/V (PONV and/or PDNV). Patients who experienced PONV had a 2.79 (95% confidence interval 2.24-3.46) times greater risk of reporting PDNV. Binary logistic regression found that younger age, opioid use, and female sex were associated with an increased likelihood of experiencing any N/V. Increased use of nitrous oxide and a higher ASA P/S class was associated with elevated likelihood of PONV, but not PDNV or PONV plus PDNV. CONCLUSIONS: Patients experiencing N/V in the PACU are observed to develop PDNV disproportionately by a factor of 2.79. The patients have distinct predictors, indicating important opportunities for care improvements beyond current guidelines.

Design, development, and face validation of an intubation simulation device using real-time force data feedback.

Objectives: To develop a novel laryngoscope device capable of dynamically measuring force and torque measurements in real-time during intubation and to explore the efficacy of such a device through a face validation simulation. Methods: The torque sensor laryngoscope is designed for use during intubation and is modeled after a standard, single-use plastic laryngoscope. After device calibration, a face validation study was performed with intubation experts in the field. Quantitative data (intubation force metrics) and qualitative data (expert feedback on the device) were collected from three intubations using a Mac blade and three intubations with the Miller blade. Results: Three experts (two anesthesiologists and one otolaryngologist) participated in the study. The mean maximum force exerted with the Mac blade was 24.5 N (95% confidence interval [CI], 22.3-26.8). The average force exerted was 13.6 N (95% CI, 11.7-15.5). The average total suspension time was 13.1 s (95% CI, 10.4-15.8). The average total impulse was 164.6 N·s (95% CI, 147.9-181.4). The mean maximum force exerted with the Miller blade was 31.6 N (95% CI, 26.4-36.8). The average force exerted was 15.8 N (95% CI, 13.8-17.9). The average total suspension time was 11.3 s (95% CI, 9.9-12.6). The average total impulse was 216.2 N·s (95% CI, 186.5-245.9). The mean maximum force (p = .0265) and total impulse (p = .009) were significantly higher in the Miller blade trials than in the Mac blade trials. Survey results found that this device, while bulky, intubated similarly to standard-use models and has potential as an intubation teaching tool. Conclusion: The torque sensor laryngoscope can measure and display real-time intubation force metrics for multiple laryngoscope blades. Initial validation studies showed a significantly lower maximum force and total impulse when intubating with the Mac blade than with the Miller blade. Face validation survey results were positive and suggested the potential for this device as a teaching tool. Level of Evidence: Level 5.

Post-anesthesia care unit desaturation in adult deep extubation patients.

OBJECTIVE: Deep extubation refers to endotracheal extubation performed while a patient is deeply anesthetized and without airway reflexes. After deep extubation, patients are sent to the post-anesthesia care unit (PACU) to recover, an area with notably different management and staffing than the operating room (OR). One of the most frequent and concerning complications to occur in the PACU is hypoxemia. As such, this study seeks to evaluate the incidence of desaturation, defined by SpO2 < 90% for longer than 10 s, in the PACU following deep extubation. Additionally, we hope to assess the consequence of desaturation on perioperative workflow by comparing PACU recovery times. RESULTS: Following deep extubation, 4.3% of patients (13/300) experienced desaturation in the PACU. Every episode was notably minor, with patients reverting to normal saturation levels within a minute. Of the 26 case factors assessed, 24 had no significant association desaturation in the PACU, including the amount of time spent in the PACU. History of asthma was the only statistically significant factor found to be positively associated with desaturation. We find that PACU desaturation episodes following deep extubation are rare. Our findings suggest that deep extubation is a viable and safe option for patients without significant respiratory tract pathology.

Aerosolization During Common Ventilation Scenarios.

Otolaryngologists are at increased risk for exposure to suspected aerosol-generating procedures during the ongoing coronavirus disease 2019 (COVID-19) pandemic. In the present study, we sought to quantify differences in aerosol generation during common ventilation scenarios. We performed a series of 30-second ventilation experiments on porcine larynx-trachea-lung specimens. We used an optical particle sizer to quantify the number of 1- to 10-µm particles observed per 30-second period (PP30). No significant aerosols were observed with ventilation of intubated specimens (10.8 ± 2.4 PP30 vs background 9.5 ± 2.1, P = 1.0000). Simulated coughing through a tracheostomy produced 53.5 ± 25.2 PP30, significantly more than background (P = .0121) and ventilation of an intubated specimen (P = .0401). These data suggest that undisturbed ventilation and thus intubation without stimulation or coughing may be safer than believed. Coughing increases aerosol production, particularly via tracheostomy. Otolaryngologists who frequently manage patient airways and perform tracheostomy are at increased risk for aerosol exposure and require appropriate personal protective equipment, especially during the ongoing COVID-19 pandemic.

Successful Use of High-Flow Nasal Cannula for Concurrent Vocal Cord Electromyography and Tubeless Microlaryngeal Surgery in a Spontaneously Breathing Adult Patient: A Case Report.

Ventilation during microlaryngoscopy previously included jet ventilation, microlaryngeal endotracheal tubes, and extended apnea. Historically, apneic oxygenation provided a tubeless field but limited operative time. Increased utilization of high-flow nasal cannula in intensive care units and operating rooms has created new opportunities to expand tubeless microlaryngoscopy. Although few studies have described high-flow nasal cannula for microlaryngoscopy, there remains much to be explored. In this case report, we describe the unique setting of utilizing high-flow nasal cannula in a spontaneously breathing patient to create an optimal tubeless surgical field for both microlaryngoscopy and vocal cord electromyography.

Oxytocin and Oxytocinase in the Obese and Nonobese Parturients during Induction and Augmentation of Labor.

Objective To investigate differences in oxytocin (OXT) biodistribution between nonobese and obese parturients during labor. Study Design Patients with body mass index (BMI) of either ≥ 18 ≤ 24.9 kg/m 2 ("nonobese") or ≥ 30 kg/m 2 ("obese") undergoing elective induction of labor were included ( N = 25 each). Blood samples were collected at baseline (T 0 ), and 20 minutes after maximal OXT augmentation or adequate uterine contractions (T 1 ) for OXT and oxytocinase assays. A mixed-model repeated-measures analysis of variance was used to test for group versus time interaction and analysis of covariance to detect a difference in OXT level at T 1 . Data presented as mean ± standard deviation or median (interquartile range), with p < 0.05 considered significant. Results The mean BMIs (kg/m 2 ) were 22.1 ± 1.6 and 35.9 ± 5.1 in the nonobese and obese groups, respectively. No differences were observed in either the duration of OXT infusion, total dose of OXT, or plasma OXT (pg/mL) either at T 0 or T 1 . However, plasma oxytocinase (ng/mL) was significantly lower at T 0 (1.41 [0.67, 3.51] vs. 0.40 [0.29, 1.12]; p = 0.03) in the obese group. Conclusion We provide preliminary evidence that the disposition of OXT may not be different between obese and nonobese women during labor.

Enhancing DNA vaccine potency by coadministration of DNA encoding antiapoptotic proteins.

Intradermal vaccination by gene gun efficiently delivers DNA vaccines into DCs of the skin, resulting in the activation and priming of antigen-specific T cells in vivo. DCs, however, have a limited life span, hindering their long-term ability to prime antigen-specific T cells. We reason that a strategy that prolongs the survival of DNA-transduced DCs will enhance priming of antigen-specific T cells and DNA vaccine potency. Here we show that codelivery of DNA encoding inhibitors of apoptosis (BCL-xL, BCL-2, XIAP, dominant negative caspase-9, or dominant negative caspase-8) with DNA encoding model antigens prolongs the survival of transduced DCs. More importantly, vaccinated mice exhibited significant enhancement in antigen-specific CD8+ T cell immune responses, resulting in a potent antitumor effect against antigen-expressing tumors. Among these antiapoptotic factors, BCL-xL demonstrated the greatest enhancement in antigen-specific immune responses and antitumor effects. Thus, coadministration of DNA vaccines with DNA encoding antiapoptotic proteins represents an innovative approach to enhance DNA vaccine potency.

Enhancing major histocompatibility complex class I antigen presentation by targeting antigen to centrosomes.

Several strategies that increase proteasomal degradation of antigen have been shown to improve MHC class I presentation of antigen. Because recent studies have demonstrated that the centrosome is a subcellular compartment rich in proteasomes, we hypothesized that targeting a tumor antigen to centrosomal compartments would enhance both the MHC class I presentation of antigen and the vaccine potency. We, therefore, created a chimera of gamma-tubulin, an established centrosomal marker, with a model tumor antigen, human papillomavirus type 16 (HPV-16) E7, in a DNA vaccine. The linkage of gamma-tubulin to E7-targeted antigen to centrosomal compartments, resulted in enhanced MHC class I presentation of E7, and led to a marked increase in the number of E7-specific CD8(+) T-cell precursors as well as a potent CD4-independent antitumor effect against an E7-expressing tumor cell line, TC-1. In addition, vaccination with gamma-tubulin/E7 DNA in transporter associated with antigen presentation (TAP)-1-knockout mice revealed that the enhancement of E7-specific CD8(+) T-cell immune responses is TAP-1-dependent. Our data suggest that the centrosome may be an important locus for MHC class I antigen processing and that targeting antigen to the centrosome can improve DNA vaccine potency.

Vaccination with a DNA vaccine encoding herpes simplex virus type 1 VP22 linked to antigen generates long-term antigen-specific CD8-positive memory T cells and protective immunity.

Intradermal vaccination with DNA encoding herpes simplex virus type 1 (HSV-1) VP22 linked to antigen leads to spread of antigen within the epithelium and results in enhanced antigen-specific CD8+ T cell immune responses in vaccinated mice. In this study, we characterized the number of antigen-expressing dendritic cells (DCs) in the draining lymph nodes of vaccinated mice and determined whether the linkage of VP22 to antigen would influence the ability of antigen-expressing DCs to activate antigen-specific CD8+ T cells in vivo. Vaccination with DNA encoding HSV-1 VP22 linked to human papillomavirus type 16 E7 antigen generated more antigen-expressing DCs in the draining lymph nodes of vaccinated mice than E7 alone. In addition, the linkage of VP22 to E7 improved the MHC class I presentation of E7 in transfected DCs and led to enhanced activation of E7-specific CD8+ T cells. We also observed that vaccination with DNA encoding VP22 linked to E7 generated more E7-specific CD8+ memory T cells, and enhanced long-term protective antitumor immunity against an E7-expressing tumor in vaccinated mice compared with vaccination with DNA encoding E7 alone. Thus, administration of DNA encoding VP22 linked to antigen represents a plausible approach for the development of protective DNA vaccines.

Peptide-MHC heterodimers show that thymic positive selection requires a more restricted set of self-peptides than negative selection.

T cell selection and maturation in the thymus depends on the interactions between T cell receptors (TCRs) and different self-peptide-major histocompatibility complex (pMHC) molecules. We show that the affinity of the OT-I TCR for its endogenous positively selecting ligands, Catnb-H-2Kb and Cappa1-H-2Kb, is significantly lower than for previously reported positively selecting altered peptide ligands. To understand how these extremely weak endogenous ligands produce signals in maturing thymocytes, we generated soluble monomeric and dimeric peptide-H-2Kb ligands. Soluble monomeric ovalbumin (OVA)-Kb molecules elicited no detectable signaling in OT-I thymocytes, whereas heterodimers of OVA-Kb paired with positively selecting or nonselecting endogenous peptides, but not an engineered null peptide, induced deletion. In contrast, dimer-induced positive selection was much more sensitive to the identity of the partner peptide. Catnb-Kb-Catnb-Kb homodimers, but not heterodimers of Catnb-Kb paired with a nonselecting peptide-Kb, induced positive selection, even though both ligands bind the OT-I TCR with detectable affinity. Thus, both positive and negative selection can be driven by dimeric but not monomeric ligands. In addition, positive selection has much more stringent requirements for the partner self-pMHC.

A role for "self" in T-cell activation.

The mechanisms by which alphabeta T-cells are selected in the thymus and then recognize peptide MHC (pMHC) complexes in the periphery remain an enigma. Recent work particularly with respect to quantification of T-cell sensitivity and the role of self-ligands in T-cell activation has provided some important clues to the details of how TCR signaling might be initiated. Here, we highlight recent experimental data that provides insights into the initiation of T-cell activation and also discuss the main controversies and uncertainties in this area.

Improving DNA vaccine potency by linking Marek's disease virus type 1 VP22 to an antigen.

We have previously employed an intercellular spreading strategy using herpes simplex virus type 1 (HSV-1) VP22 protein to enhance DNA vaccine potency because DNA vaccines lack the intrinsic ability to amplify in cells. Recently, studies have demonstrated that the protein encoded by UL49 of Marek's disease virus type 1 (MDV-1) exhibits some degree of homology to the HSV-1 VP22 protein and features the property of intercellular transport. We therefore generated a DNA vaccine encoding MDV-1 VP22 linked to a model antigen, human papillomavirus type 16 E7. We demonstrated that compared with mice vaccinated with DNA encoding wild-type E7, mice vaccinated with MDV-1 VP22/E7 DNA exhibited a significant increase in number of gamma-interferon-secreting, E7-specific CD8(+)-T-cell precursors as well as stronger tumor prevention and treatment effects. Furthermore, our data indicated that the antitumor effect was CD8 dependent. These results suggested that the development of vaccines encoding VP22 fused to a target antigen might be a promising strategy for improving DNA vaccine potency.

Comparison of the CD8+ T cell responses and antitumor effects generated by DNA vaccine administered through gene gun, biojector, and syringe.

DNA vaccines have emerged as an attractive approach for antigen-specific cancer immunotherapy. We have previously linked Mycobacterium tuberculosis heat shock protein 70 (HSP70) to human papillomavirus type 16 (HPV-16) E7 in the context of a DNA vaccine. Vaccination with DNA encoding E7/HSP70 has generated a dramatic increase of E7-specific CD8+ T cell precursors and a strong antitumor effect against E7-expressing tumor (TC-1) in vaccinated mice. The success of our strategy has led to two phases I/II clinical trial proposals in patients with HPV-16 associated high-grade squamous intraepithelial lesion (HSIL) of the cervix and in patients with advanced HPV-associated head and neck squamous cell carcinoma (HNSCC). To translate our HPV DNA vaccines into the clinical domain, the efficacy of pNGVL4a-Sig/E7(detox)/HSP70 DNA vaccine and of various routes of administrations were assessed in mice. Our results indicated that pNGVL4a-Sig/E7(detox)/HSP70 DNA vaccine administered via gene gun generated the highest number of E7-specific CD8+ T cells. In addition, DNA vaccination via gene gun required the least dose to generate similar or slightly better antitumor effects compared to needle intramuscular (i.m.) and biojector administrations. Thus, our data suggest that DNA vaccination via gene gun represents the most potent regimen for DNA administration.