Scaling up Functional Analyses of the G Protein-Coupled Receptor Rhodopsin.

Eukaryotic cells use G protein-coupled receptors (GPCRs) to convert external stimuli into internal signals to elicit cellular responses. However, how mutations in GPCR-coding genes affect GPCR activation and downstream signaling pathways remain poorly understood. Approaches such as deep mutational scanning show promise in investigations of GPCRs, but a high-throughput method to measure rhodopsin activation has yet to be achieved. Here, we scale up a fluorescent reporter assay in budding yeast that we engineered to study rhodopsin's light-activated signal transduction. Using this approach, we measured the mutational effects of over 1200 individual human rhodopsin mutants, generated by low-frequency random mutagenesis of the GPCR rhodopsin (RHO) gene. Analysis of the data in the context of rhodopsin's three-dimensional structure reveals that transmembrane helices are generally less tolerant to mutations compared to flanking helices that face the lipid bilayer, which suggest that mutational tolerance is contingent on both the local environment surrounding specific residues and the specific position of these residues in the protein structure. Comparison of functional scores from our screen to clinically identified rhodopsin disease variants found many pathogenic mutants to be loss of function. Lastly, functional scores from our assay were consistent with a complex counterion mechanism involved in ligand-binding and rhodopsin activation. Our results demonstrate that deep mutational scanning is possible for rhodopsin activation and can be an effective method for revealing properties of mutational tolerance that may be generalizable to other transmembrane proteins.

Phylogenomic analyses re-examine the evolution of reinforcement and hypothesized hybrid speciation in Phlox wildflowers.

The tree of life is riddled with reticulate evolutionary histories, and some clades, such as the eastern standing Phlox, appear to be hotspots of hybridization. In this group, there are two cases of reinforcement and nine hypothesized hybrid species. Given their historical importance in our understanding of plant speciation, the relationships between these taxa and the role of hybridization in their diversification require genomic validation. Using phylogenomic analyses, we resolve the evolutionary relationships of the eastern standing Phlox and evaluate hypotheses about whether and how hybridization and gene flow played a role in their diversification. Our results provide novel resolution of the phylogenetic relationships in this group, including paraphyly across some taxa. We identify gene flow during one case of reinforcement and find genomic support for a hybrid lineage underlying one of the five hypothesized homoploid hybrid speciation events. Additionally, we estimate the ancestries of four allotetraploid hybrid species. Our results are consistent with hybridization contributing to diverse evolutionary outcomes within this group; although, not as extensively as previously hypothesized. This study demonstrates the importance of phylogenomics in evaluating hypothesized evolutionary histories of non-model systems and adds to the growing support of interspecific genetic exchange in the generation of biodiversity.

Performance of the minimalistic hybrid approach algorithm versus other conventional algorithms in the percutaneous treatment of chronic total occlusions.

BACKGROUND: The "Minimalistic Hybrid Approach" (MHA) has been proposed to reduce the invasiveness of chronic total occlusion (CTO) percutaneous coronary intervention (PCI). AIMS: This study aims to assess whether MHA may also reduce the utilization of PCI resources (devices, radiations, and contrast) by comparing it with other conventional algorithms. METHODS: We aimed to assess the impact of MHA on device, radiation, and contrast usage during CTO-PCI analyzing data from the Belgian Working Group on CTO (BWG-CTO) registry. Patients were divided, depending on the algorithm used, into two groups: Conventional versus Minimalistic. Primary objectives were procedure performance measures such as device usage (microcatheters and guidewires), radiological parameters, and contrast use. At 1-year follow-up, patients were evaluated for target vessel failure (TVF), defined as a composite of cardiac death, new myocardial infarction, and target vessel revascularization. RESULTS: Overall, we analyzed 821 CTO-PCIs (Conventional n = 650, Minimalistic n = 171). The Minimalistic group demonstrated higher complexity of CTO lesions. After adjusting for propensity score, the Minimalistic group had a significantly lower number of microcatheters used (1.49 ± 0.85 vs. 1.24 ± 0.64, p = 0.026), while the number of guidewires was comparable (4.80 ± 3.29 vs. 4.35 ± 2.94, p = 0.30). Both groups had similar rates of success and procedural complications, as well as comparable procedural and fluoroscopic times and contrast volume used. At the 1-year follow-up, both groups showed comparable rates of TVF (hazard ratio: 0.57; 95% confidence interval: 0.24-1.34, p = 0.195). CONCLUSION: The MHA may slightly reduce the number of dedicated devices used during CTO-PCI, without adversely affecting the procedural success or long-term outcome.

Photosealed Neurorrhaphy Using Autologous Tissue.

Photochemical sealing of a nerve wrap over the repair site isolates and optimizes the regenerating nerve microenvironment. To facilitate clinical adoption of the technology, we investigated photosealed autologous tissue in a rodent sciatic nerve transection and repair model. Rats underwent transection of the sciatic nerve with repair performed in three groups: standard microsurgical neurorrhaphy (SN) and photochemical sealing with a crosslinked human amnion (xHAM) or autologous vein. Functional recovery was assessed at four-week intervals using footprint analysis. Gastrocnemius muscle mass preservation, histology, and nerve histomorphometry were evaluated at 120 days. Nerves treated with a PTB-sealed autologous vein improved functional recovery at 120 days although the comparison between groups was not significantly different (SN: -58.4 +/- 10.9; XHAM: -57.9 +/- 8.7; Vein: -52.4 +/- 17.1). Good muscle mass preservation was observed in all groups, with no statistical differences between groups (SN: 69 +/- 7%; XHAM: 70 +/- 7%; Vein: 70 +/- 7%). Histomorphometry showed good axonal regeneration in all repair techniques. These results demonstrate that peripheral nerve repair using photosealed autologous veins produced regeneration at least equivalent to current gold-standard microsurgery. The use of autologous veins removes costs and foreign body concerns and would be readily available during surgery. This study illustrates a new repair method that could restore normal endoneurial homeostasis with minimal trauma following severe nerve injury.

Assessing evidence accumulation and rule learning in humans with an online game.

Evidence accumulation, an essential component of perception and decision making, is frequently studied with psychophysical tasks involving noisy or ambiguous stimuli. In these tasks, participants typically receive verbal or written instructions that describe the strategy that should be used to guide decisions. Although convenient and effective, explicit instructions can influence learning and decision making strategies and can limit comparisons with animal models, in which behaviors are reinforced through feedback. Here, we developed an online video game and nonverbal training pipeline, inspired by pulse-based tasks for rodents, as an alternative to traditional psychophysical tasks used to study evidence accumulation. Using this game, we collected behavioral data from hundreds of participants trained with an explicit description of the decision rule or with experiential feedback. Participants trained with feedback alone learned the game rules rapidly and used strategies and displayed biases similar to those who received explicit instructions. Finally, by leveraging data across hundreds of participants, we show that perceptual judgments were well described by an accumulation process in which noise scaled nonlinearly with evidence, consistent with previous animal studies but inconsistent with diffusion models widely used to describe perceptual decisions in humans. These results challenge the conventional description of the accumulation process and suggest that online games provide a valuable platform to examine perceptual decision making and learning in humans. In addition, the feedback-based training pipeline developed for this game may be useful for evaluating perceptual decision making in human populations with difficulty following verbal instructions.NEW & NOTEWORTHY Perceptual uncertainty sets critical constraints on our ability to accumulate evidence and make decisions; however, its sources remain unclear. We developed a video game, and feedback-based training pipeline, to study uncertainty during decision making. Leveraging choices from hundreds of subjects, we demonstrate that human choices are inconsistent with popular diffusion models of human decision making and instead are best fit by models in which perceptual uncertainty scales nonlinearly with the strength of sensory evidence.

Percutaneous treatment of left circumflex coronary artery injury related to mitral valve surgery: Case series and systematic review of the literature.

Left circumflex coronary artery (LCx) injury related to mitral valve surgery is a rare complication. The best treatment option is not defined, and percutaneous coronary intervention (PCI) may represent an effective treatment to avoid prolonged myocardial ischemia. To evaluate feasibility and efficacy of PCI treatment, all records of LCx injury related to mitral valve surgery and treated with PCI were included after a systematic PubMed searching. Moreover, we retrospectively analyzed our single-center PCI database and patients fulfilling the inclusion criteria were included. Patients undergoing transcatheter mitral valve intervention, non-mitral valve surgery, conservatively or surgically treated after LCx injury were excluded. Data about patient characteristics, procedural details, PCI success, and in-hospital mortality were collected. Fifty-six patients were included, 58.9% were male (n = 33) and the median age was 60.5 years (IQR = 21.75). The majority had left dominant or codominant coronary system (62.2%, n = 28 and 15.6%, n = 7, respectively). Clinical manifestations ranged from hemodynamic stability (21.1%, n = 8) to hemodynamic instability (42.1%, n = 16) and cardiac arrest (18.4%, n = 7). On ECG, 23.5% of patients (n = 12) presented ST-segment depression, 58.8% (n = 30) ST-segment elevation, 7.8% (n = 4) atrioventricular block, and 29.4% (n = 15) ventricular arrhythmias. Left ventricle dysfunction was present in 52.3% (n = 22) of patients and wall motion abnormalities in 71.4% (n = 30). PCI success rate was 82.1% (n = 46) and in-hospital mortality 4.5% (n = 2). LCx injury related to mitral surgery is a rare complication characterized by an increased risk of mortality. PCI seems a feasible treatment option, still burdened by suboptimal results, probably related to the technical challenges posed by the surgical failure.

The First Statewide Implementation of a Regional Disaster Teleconsultation System to Expand Critical Care Surge Capacity: A Case Study in Vermont.

Background: In December 2021, the Region 1 Disaster Health Response System, the state of Vermont, and the National Emergency Tele-Critical Care Network partnered to provide statewide access to disaster teleconsultations during COVID-19 surge conditions. In this case report, we describe how a disaster teleconsultation system was implemented in Vermont to provide access to temporary tele-critical care consultations during the Omicron COVID-19 surge. Methods: We measured the time from request of service to implementation and calculated descriptive statistics. Results: Seven of Vermont's 14 hospitals requested the service. Despite a technology solution capable of providing services within hours, mean time to service implementation was 27 days (interquartile range 20-41 days). Conclusions: Integration of disaster teleconsultation systems into state and local emergency management plans are needed to bring administrative start-up times in line with technical readiness.

Light-Activated Vascular Anastomosis.

Background. There have been few advances in technique since vascular anastomosis was performed with silk suture on a curved needle in 1902. This technique results in disruption of the endothelium with exposed intraluminal suture, both of which may lead to thrombocyte aggregation, intimal hyperplasia, and vascular stenosis. A variety of alternative techniques have been explored, with limited success. Photochemical tissue bonding (PTB) is a light-activated methodology of rapidly cross-linking tissue interfaces at the molecular level. Herein, we describe a new technique for anastomosis of venous interposition graft in an ovine model of femoral artery bypass utilizing PTB. Methods. Polypay specific pathogen free sheep (n = 5; 40-45 kg) underwent femoral artery bypass utilizing saphenous vein. The femoral artery was transected and reversed saphenous vein was implanted as an interposition graft. The proximal anastomosis was created as a vein-over-artery cuff utilizing PTB, and the distal anastomosis was created with standard interrupted 8-0 polypropylene suture. Four weeks post-index operation, femoral angiogram was performed to evaluate patency, tortuosity, and luminal diameter. All bypass grafts were harvested and longitudinal and transverse histological sections from the proximal anastomosis were analyzed. Results. The PTB anastomoses (n = 5) were immediately watertight and patent. All animals survived the 28-day study duration. Angiography revealed patent grafts with no aneurysm or stenosis (n = 5). Histologic examination revealed integration of the venous endothelium with the arterial adventitia. Conclusion. Photochemical tissue bonding creates an immediate strong, watertight vascular anastomosis that can withstand physiologic arterial pressure and remains patent at 28 days without the need for intraluminal suture.

Minimalistic hybrid approach for the percutaneous treatment of chronic coronary total occlusions: An in-depth analysis of the whole algorithm.

INTRODUCTION: The minimalistic hybrid approach (MHA) is an algorithm to perform chronic total occlusion (CTO) percutaneous coronary intervention (PCI). The current study aims to evaluate the distribution of patients among the five different treatment strategies, the different techniques used in each strategy, the overall procedural success, and the safety of the MHA algorithm. METHODS: Data from a consecutive series of patients with a CTO who underwent elective PCI between February 2019 and July 2021 were prospectively collected and retrospectively analyzed. RESULTS: One hundred and forty-three CTOPCI in 135 patients were approached according to the MHA algorithm: 134 CTO (93.7%) were successfully recanalized and 9 procedures failed. About half of the procedures (48.3%) were approached using strategy A: antegrade "blind wiring" with contralateral retrograde options, making this the most popular strategy. A total of 89 procedures (62.2%) were completed with a single guiding catheter; in 86 (96.6%) a forearm approach was used. The remaining 54 cases were performed with dual access; in the majority of these patients (90.7%), a bilateral forearm approach was used. The only reason to use the femoral access was inadequate forearm access. One hundred and fifty-four out of 197 (78.2%) access sites were 6 French sheaths. CONCLUSION: MHA is a stepwise approach focused on the forearm approach to reduce the number of access sites and catheter size used in CTOPCI while maintaining proficiency and safety. Operators should be warned that this approach should be adopted only by experienced CTO operators who master all the strategies of the classic hybrid algorithm and the forearm approach.

Light-activated photosealing with human amniotic membrane strengthens bowel anastomosis in a hypotensive, trauma-relevant swine model.

BACKGROUND: Gastrointestinal anastomotic leakage is a dreaded complication despite advancements in surgical technique. Photochemical tissue bonding (PTB) is a method of sealing tissue surfaces utilizing photoactive dye. We evaluated if crosslinked human amniotic membrane (xHAM) photosealed over the enteroenterostomy would augment anastomotic strength in a trauma-relevant swine hemorrhagic shock model. METHODS: Yorkshire swine (40-45 kg, n = 14) underwent midline laparotomy and sharp transection of the small intestine 120 cm proximal to the ileocecal fold. Immediately following intestinal transection, a controlled arterial bleed was performed to reach hemorrhagic shock. Intestinal repair was performed after 60 minutes and autotransfusion of the withdrawn blood was performed for resuscitation. Animals were randomized to small intestinal anastomosis by one of the following methods (seven per group): suture repair (SR), or SR with PTB augmentation. Animals were euthanized at postoperative Day 28 and burst pressure (BP) strength testing was performed on all excised specimens. RESULTS: Mean BP for SR, PTB, and native tissue groups were 229 ± 40, 282 ± 21, and 282 ± 47 mmHg, respectively, with the SR group statistically significantly different on analysis of variance (p = 0.02). Post-hoc Tukey all-pairs comparison demonstrated a statistically significant difference in burst pressure strength between the SR only and the PTB group (p = 0.04). All specimens in SR group ruptured at the anastomosis upon burst pressure testing, while all specimens in the PTB group ruptured at least 2.5 cm from the anastomosis. CONCLUSION: Photosealing with xHAM significantly augments the strength of small intestinal anastomosis performed in a trauma porcine model.

A prospective evaluation of a redefined version of the "minimalistic hybrid approach" algorithm for percutaneous coronary chronic total occlusion revascularization.

OBJECTIVES: Aim of this study is to prospectively assess the feasibility of the "Minimalistic Hybrid Approach" (MHA) algorithm for chronic total occlusion (CTO) percutaneous coronary intervention (PCI). BACKGROUND: We recently described the MHA, with focus on the classic hybrid strategies (antegrade wire escalation [AWE] or retrograde wire escalation [RWE], antegrade dissection-re-entry [ADR] or retrograde dissection-re-entry [RDR]), and also on access site (favoring "wrist" approach: radial, ulnar, and distal radial), introducer French size (favoring 6 French catheters) and nonroutine initial use of dual injection. METHODS: The MHA was prospectively attempted in 56 consecutive CTO PCI in 54 patients. Technical success was defined as the achievement of TIMI 3 antegrade flow with residual stenosis <30%, procedural success was defined as technical success without in-hospital major adverse cardiovascular events. RESULTS: Mean Japanese-CTO (J-CTO) score was 2.04 ± 0.95(J-CTO score ≥ 3 in 30.4%). The lesion-based technical and procedural success were 94.6%(53/56:three failures, two in the same patient) and 91.1%(51/56:three failures, one tamponade requiring pericardiocentesis and one periprocedural infarction), the patient-based successes were: technical 98.1%(53/54) and procedural 94.4%(51/54). In 34 procedures (60.7%), the approach was single catheter (always trans-wrist besides one femoral). Out of the 22(39.3%) lesions approached with dual catheters, one was bi-femoral, the rest was bi-wrist. In 29 cases (51.8%) AWE represented the successful technique, ADR in 5(8.9%) and retrograde in 19(33.9%); 3(5.4%) were failures. CONCLUSIONS: The current study shows that the MHA algorithm is feasible in almost every CTO lesion and it can lead to extremely successful results once applied by operators well acquainted with the wrist approach and with established experience using the full spectrum of the hybrid algorithm techniques.

Coronary sinus anatomical features: Description and procedural implications during coronary sinus Reducer implantation.

OBJECTIVES: We hypothesized that some coronary sinus (CS) anatomies allow a more straightforward CS Reducer (CSR) implantation. BACKGROUND: Recent decades have seen a rise in patients with chronic angina. When complete revascularization and maximal medical therapy fail to reduce symptoms, CSR has become a new therapeutic option. METHODS: We identified a classical C-shape-a near horizontal course of the proximal portion of a circular CS-in a retrospective analysis of 47 CSR implantations and compared the procedural time, fluoroscopic time, contrast use, presence of valves or bifurcations and procedural complications with the non-C-shape CS anatomy. RESULTS: We found a significant difference in procedural (20.0 [19.0-24.7] min vs. 24.5 [20.7-51.0] min; p = .028 and fluoroscopic time (9.5 [7.5-14.5] min vs. 11.0 [7.9-30.0] min; p = .016). There was no significant difference in contrast use. The presence of bifurcations or valves along the CS course did not influence the procedural timings. CONCLUSION: This study is the first systematic evaluation of CS anatomy and its procedural implications. We identified a favorable C-shape anatomy which allows for a more straightforward implantation. Operators should be aware of the different implications of CS anatomy, their influence on guiding catheter stability and overall procedure complexity.

Toxicology Screening Testing in Patients Undergoing Spine Surgery: A Prospective Observational Pilot Study.

BACKGROUND: Chronic opioid use and polypharmacy are commonly seen in chronic pain patients presenting for spine procedures. Substance abuse and misuse have also been reported in this patient population. Negative perioperative effects have been found in patients exposed to chronic opioid, alcohol, and recreational substances. Toxicology screening testing (TST) in the perioperative period provides useful information for adequate preoperative optimization and perioperative planning. METHODS: We designed a pilot study to understand this population's preoperative habits including accuracy of self-report and TST-detected prescribed and unprescribed medications and recreational substances. We compared the results of the TST to the self-reported medications using Spearman correlations. RESULTS: Inconsistencies between TST and self-report were found in 88% of patients. Spearman correlation was 0.509 between polypharmacy and intraoperative propofol use, suggesting that propofol requirement increased as the number of substances used increased. CONCLUSIONS: TST in patients presenting for spine surgery is a useful tool to detect substances taken by patients because self-report is often inaccurate. Discrepancies decrease the opportunity for preoperative optimization and adequate perioperative preparation.

Primary Indicators to Systematically Monitor COVID-19 Mitigation and Response - Kentucky, May 19-July 15, 2020.

State and local health departments in the United States are using various indicators to identify differences in rates of reported coronavirus disease 2019 (COVID-19) and severe COVID-19 outcomes, including hospitalizations and deaths. To inform mitigation efforts, on May 19, 2020, the Kentucky Department for Public Health (KDPH) implemented a reporting system to monitor five indicators of state-level COVID-19 status to assess the ability to safely reopen: 1) composite syndromic surveillance data, 2) the number of new COVID-19 cases,* 3) the number of COVID-19-associated deaths,† 4) health care capacity data, and 5) public health capacity for contact tracing (contact tracing capacity). Using standardized methods, KDPH compiles an indicator monitoring report (IMR) to provide daily analysis of these five indicators, which are combined with publicly available data into a user-friendly composite status that KDPH and local policy makers use to assess state-level COVID-19 hazard status. During May 19-July 15, 2020, Kentucky reported 12,742 COVID-19 cases, and 299 COVID-19-related deaths (1). The mean composite state-level hazard status during May 19-July 15 was 2.5 (fair to moderate). IMR review led to county-level hotspot identification (identification of counties meeting criteria for temporal increases in number of cases and incidence) and facilitated collaboration among KDPH and local authorities on decisions regarding mitigation efforts. Kentucky's IMR might easily be adopted by state and local health departments in other jurisdictions to guide decision-making for COVID-19 mitigation, response, and reopening.

Advanced Digital Health Technologies for COVID-19 and Future Emergencies.

Background: Coronavirus disease 2019 (COVID-19) has led to a national health care emergency in the United States and exposed resource shortages, particularly of health care providers trained to provide critical or intensive care. This article describes how digital health technologies are being or could be used for COVID-19 mitigation. It then proposes the National Emergency Tele-Critical Care Network (NETCCN), which would combine digital health technologies to address this and future crises. Methods: Subject matter experts from the Society of Critical Care Medicine and the Telemedicine and Advanced Technology Research Center examined the peer-reviewed literature and science/technology news to see what digital health technologies have already been or could be implemented to (1) support patients while limiting COVID-19 transmission, (2) increase health care providers' capability and capacity, and (3) predict/prevent future outbreaks. Results: Major technologies identified included telemedicine and mobile care (for COVID-19 as well as routine care), tiered telementoring, telecritical care, robotics, and artificial intelligence for monitoring. Several of these could be assimilated to form an interoperable scalable NETCCN. NETCCN would assist health care providers, wherever they are located, by obtaining real-time patient and supplies data and disseminating critical care expertise. NETCCN capabilities should be maintained between disasters and regularly tested to ensure continual readiness. Conclusions: COVID-19 has demonstrated the impact of a large-scale health emergency on the existing infrastructures. Short term, an approach to meeting this challenge is to adopt existing digital health technologies. Long term, developing a NETCCN may ensure that the necessary ecosystem is available to respond to future emergencies.

Is a covered stent justifiable in the treatment of coronary artery perforation? An observational analysis of long-term results of two different covered stent types.

OBJECTIVES: In this retrospective observational study, we investigate outcome of patients treated with or without covered stent (CS) implantation in the management of coronary artery perforation (CAP) during coronary intervention. BACKGROUND: CSs have shown to be effective devices to achieve acute hemostasis in large CAP. However, doubts have been raised regarding their long-term outcome. METHODS: Data of 19 061 PCI procedures during a 10-year period were reviewed. Fifty-five cases of large CAP were withheld (Ellis type 2, 3 or cavity spilling). All medical and procedural records of these cases were retrospectively reviewed. RESULTS: Twenty-four (43.6%) patients were treated with CS implantation (15 polytetrafluoroethylene and 9 pericardium CSs). Twenty-six (47.3%) patients were managed without CS implantation, of whom five had unsuccessful delivery of a CS (stent delivery failure 17.2%). Although significantly more Ellis type-3 perforations were present in the CS group compared to the Non-CS group (75.0% vs 45.2%; P = 0.03), in-hospital mortality was not significantly different (8.3% vs 6.4%; [P = 0.79]). We observed a high rate of CS restenosis (29.2%) but a lower rate of CS thrombosis (4.2%). Despite these observations, 5-year MACE and all-cause mortality were not significantly different between CS and Non-CS group (respectively, 58.8% vs 50.0% (P = 0.26) and 26.7% vs 13.3% (P = 0.36)). CONCLUSION: Although deliverability of CSs was not flawless and a high rate of CS restenosis appeared, short- and long-term outcome were comparable between patients treated with or without CS. Therefore, CSs are justifiable in the treatment of CAP.

Government Legislation in Response to the Opioid Epidemic.

PURPOSE OF REVIEW: Opioid misuse and abuse in the USA has evolved into an epidemic of tragic pain and suffering, resulting in the estimated death of over 64,000 people in 2016. Governmental regulation has escalated alongside growing awareness of the epidemic's severity, both on the state and federal levels. RECENT FINDINGS: This article reviews the timeline of government interventions from the late 1990s to today, including the declaration of the opioid crisis as a national public health emergency and the resultant changes in funding and policy across myriad agencies. Aspects of the cultural climate that fuel the epidemic, and foundational change that may promote sustained success against it, are detailed within as well. As a consequence of misuse and abuse of opioids, governmental regulation has attempted to safeguard society, and clinicians should appreciate changes and expectations of prescribers.

The Period 2 Enhancer Nobiletin as Novel Therapy in Murine Models of Circadian Disruption Resembling Delirium.

OBJECTIVES: Delirium occurs in approximately 30% of critically ill patients, and the risk of dying during admission doubles in those patients. Molecular mechanisms causing delirium are largely unknown. However, critical illness and the ICU environment consistently disrupt circadian rhythms, and circadian disruptions are strongly associated with delirium. Exposure to benzodiazepines and constant light are suspected risk factors for the development of delirium. Thus, we tested the functional role of the circadian rhythm protein Period 2 (PER2) in different mouse models resembling delirium. DESIGN: Animal study. SETTING: University experimental laboratory. SUBJECTS: Wildtype, Per2 mice. INTERVENTIONS: Midazolam, lipopolysaccharide (lipopolysaccharide), constant light, nobiletin, or sham-treated animals. MEASUREMENTS AND MAIN RESULTS: Midazolam significantly reduced the expression of PER2 in the suprachiasmatic nucleus and the hippocampus of wild-type mice. Behavioral tests following midazolam exposure revealed a robust phenotype including executive dysfunction and memory impairment suggestive of delirium. These findings indicated a critical role of hippocampal expressed PER2. Similar results were obtained in mice exposed to lipopolysaccharide or constant light. Subsequent studies in Per2 mice confirmed a functional role of PER2 in a midazolam-induced delirium-like phenotype. Using the small molecule nobiletin to enhance PER2 function, the cognitive deficits induced by midazolam or constant light were attenuated in wild-type mice. CONCLUSIONS: These experiments identify a novel role for PER2 during a midazolam- or constant light-induced delirium-like state, highlight the importance of hippocampal PER2 expression for cognitive function, and suggest the PER2 enhancer nobiletin as potential therapy in delirium-like conditions associated with circadian disruption.

Regulatory IgDhi B Cells Suppress T Cell Function via IL-10 and PD-L1 during Progressive Visceral Leishmaniasis.

During visceral leishmaniasis (VL), Th1-based inflammation is induced to control intracellular parasites. Inflammation-based pathology was shown to be dampened by IL-10 and eventual programmed death 1-mediated T cell exhaustion. Cell type(s) responsible for the initiation of T cell-produced IL-10 during VL are unknown. CD19(+), CD5(-), CD1d(-), IgD(hi) regulatory B cells from healthy controls produced IL-10 in the absence of infection or stimulation, in contrast to IgD(lo/neg) B cells. IgD(hi) B cells may have a de novo versus induced regulatory program. The population of IgD(hi) B cells increased 3-fold as VL progressed. B cells from VL dogs were necessary and sufficient to suppress Th1 cell effector function. IgD(hi) B cells induced IL-10 production by T cells and IgD(lo) B cells. Blockage of B cell-specific PD-L1 restored Th1 responses. IgD(hi) regulatory B cells represent a novel regulatory B cell that may precipitate T cell exhaustion during VL.