Human Performance of Novice Schedulers for Complex Spaceflight Operations Timelines.

OBJECTIVE: Investigate the effects of scheduling task complexity on human performance for novice schedulers creating spaceflight timelines. BACKGROUND: Future astronauts will be expected to self-schedule, yet will not be experts in creating timelines that meet the complex constraints inherent to spaceflight operations. METHOD: Conducted a within-subjects experiment to evaluate scheduling task performance in terms of scheduling efficiency, effectiveness, workload, and situation awareness while manipulating scheduling task complexity according to the number of constraints and type of constraints. RESULTS: Each participant (n = 15) completed a set of scheduling problems. Results showed main effects of the number of constraints and type of constraint on efficiency, effectiveness, and workload. Significant interactions were observed in situation awareness and workload for certain types of constraints. Results also suggest that a lower number of constraints may be manageable by novice schedulers when compared to scheduling activities without constraints. CONCLUSION: Results suggest that novice schedulers' performance decreases with a high number of constraints, and future scheduling aids may need to target a specific type of constraint. APPLICATION: Knowledge on the effect of scheduling task complexity will help design scheduling systems that will enable self-scheduling for future astronauts. It will also inform other domains that conduct complex scheduling, such as nursing and manufacturing.

Prolactin and prolactin receptor expression in the HPG axis and crop during parental care in both sexes of a biparental bird (Columba livia).

During breeding, multiple circulating hormones, including prolactin, facilitate reproductive transitions in species that exhibit parental care. Prolactin underlies parental behaviors and related physiological changes across many vertebrates, including birds and mammals. While circulating prolactin levels often fluctuate across breeding, less is known about how relevant target tissues vary in their prolactin responsiveness via prolactin receptor (PRLR) expression. Recent studies have also investigated prolactin (PRL) gene expression outside of the pituitary (i.e., extra-pituitary PRL), but how PRL gene expression varies during parental care in non-pituitary tissue (e.g., hypothalamus, gonads) remains largely unknown. Further, it is unclear if and how tissue-specific PRL and PRLR vary between the sexes during biparental care. To address this, we measured PRL and PRLR gene expression in tissues relevant to parental care, the endocrine reproductive hypothalamic-pituitary- gonadal (HPG) axis and the crop (a tissue with a similar function as the mammalian mammary gland), across various reproductive stages in both sexes of a biparental bird, the rock dove (Columba livia). We also assessed how these genes responded to changes in offspring presence by adding chicks mid-incubation, simulating an early hatch when prolactin levels were still moderately low. We found that pituitary PRL expression showed similar increases as plasma prolactin levels, and detected extra-pituitary PRL in the hypothalamus, gonads and crop. Hypothalamic and gonadal PRLR expression also changed as birds began incubation. Crop PRLR expression correlated with plasma prolactin, peaking when chicks hatched. In response to replacing eggs with a novel chick mid-incubation, hypothalamic and gonadal PRL and PRLR gene expression differed significantly compared to mid-incubation controls, even when plasma prolactin levels did not differ. We also found sex differences in PRL and PRLR that suggest gene expression may allow males to compensate for lower levels in prolactin by upregulating PRLR in all tissues. Overall, this study advances our understanding of how tissue-specific changes in responsiveness to parental hormones may differ across key reproductive transitions, in response to offspring cues, and between the sexes.

Cannulation-Related Complications on Veno-Arterial Extracorporeal Membrane Oxygenation: Prevalence and Effect on Mortality.

Cannulation-related complications are a known source of morbidity in patients supported on veno-arterial extracorporeal membrane oxygenation (VA-ECMO). Despite its prevalence, little is known regarding the outcomes of patients who suffer such complications. This is a single institution review of cannulation-related complications and its effect on mortality in patients supported on VA-ECMO from January 2010-2015 using three cannulation strategies: axillary, femoral, and central. Complications were defined as advanced if they required major interventions (fasciotomy, amputation, site conversion). Patients were divided into two groups (complication present vs. not present) and Kaplan-Meier analysis was performed to determine any differences in their survival distributions. There were 103 patients supported on VA-ECMO: 41 (40%), 36 (35%), and 26 (25%) were cannulated via axillary, femoral, and central access, respectively. Cannulation-related complications occurred in 33 (32%) patients and this did not differ significantly between either axillary (34%), femoral (36%), or central (23%) strategies (P = 0.52). The most common complications encountered were hemorrhage and limb ischemia in 19 (18%) and 11 (11%) patients. Hemorrhagic complications did not differ between groups (P = 0.37), while limb ischemia and hyperperfusion were significantly associated with femoral and axillary cannulation, at a rate of 25% (P < 0.01) and 15% (P = 0.01), respectively. There was no difference in the incidence of advanced complications between cannulation groups: axillary (12%) vs. femoral (14%) vs. central (8%; P = 0.75). In addition, no increase in mortality was noted in patients who developed a cannulation-related complication by Kaplan-Meier estimates (P = 0.37). Cannulation-related complications affect a significant proportion of patients supported on VA-ECMO but do not differ in incidence between different cannulation strategies and do not affect patient mortality. Improved efforts at preventing these complications need to be developed to avoid the additional morbidity in an already critical patient population.

Coil embolization of a symptomatic left internal mammary arteriovenous fistula.

Internal mammary artery (IMA) arteriovenous fistulae (AVF) are exceedingly rare. There have been a few case reports documenting incidences of IMA AVFs arising from traumatic, iatrogenic, and congenital causes. Recommendations for management of IMA AVFs vary from open surgical ligation-excision to transcatheter embolization to observation. We present an unusual case of a patient who presented with ventricular arrhythmias and heart failure symptoms due to a left IMA AVF that formed after open heart surgery. The patient ultimately underwent percutaneous embolization of the fistulous connection.

Endocarditis of Amplatzer occluder devices after percutaneous closure of a mitral paravalvular leak.

Symptomatic paravalvular leaks (PVL) are a relatively uncommon, but potentially significant postoperative complication of valve replacement surgery. Percutaneous repair of PVLs has become an increasingly utilized approach in patients whose comorbidities obviate surgical repair. We present an interesting case of a gentleman who underwent successful repair of a mitral PVL with Amplatzer devices following initial aortic and mitral valve replacements for bacterial endocarditis. He later developed fungal endocarditis that ultimately required re-operation to remove the devices and replace his mitral and aortic valves. This complication of closure devices, although reportedly rare, should be considered when contemplating a percutaneous approach. © 2012 Wiley Periodicals, Inc.

Surgical and Device Interventions in the Treatment of Chronic Thromboembolic Disease.

Chronic thromboembolic pulmonary disease (CTEPD) is characterized by unresolved clot burden in large pulmonary arteries, obstructive disease in smaller arteries, and increased downstream clot burden. This occurs in the setting of abnormal fibrinolysis or hematological disorders. Up to 50% of patients in some studies are unaware of a self-history of a deep venous thrombosis or pulmonary embolism. Ultimately, they present with symptoms of pulmonary hypertension (PH), which can result in right heart failure (RHF). Pulmonary endarterectomy (PEA) is curative, though many patients have prohibitive surgical risk or surgically inaccessible disease, warranting other interventions such as balloon pulmonary angioplasty (BPA) and medical therapy. Rarely, other treatment options may be implemented. We focus this review on PEA and BPA, with an overview of the history of CTEPD and the evolution of these procedures. We will briefly discuss other treatment modalities.

VA-ECMO-Facilitated Clot Debulking and PFO Closure in a Patient With Recurrent Pulmonary Thromboses.

A 27-year-old female with stage IIIc cervical cancer presented with dyspnea and stroke symptoms. Work-up revealed bilateral pulmonary embolisms, acute/subacute strokes, and a patent foramen ovale. After multidisciplinary team discussion, the patient underwent patent foramen ovale closure, complicated by cardiogenic shock requiring venoarterial extracorporeal membrane oxygenation. She successfully underwent pulmonary thromboendarterectomy, extracorporeal membrane oxygenation decannulation, and hospital discharge.

Whole-brain mapping of long-range inputs to the VIP-expressing inhibitory neurons in the primary motor cortex.

The primary motor cortex (MOp) is an important site for motor skill learning. Interestingly, neurons in MOp possess reward-related activity, presumably to facilitate reward-based motor learning. While pyramidal neurons (PNs) and different subtypes of GABAergic inhibitory interneurons (INs) in MOp all undergo cell-type specific plastic changes during motor learning, the vasoactive intestinal peptide-expressing inhibitory interneurons (VIP-INs) in MOp have been shown to preferentially respond to reward and play a critical role in the early phases of motor learning by triggering local circuit plasticity. To understand how VIP-INs might integrate various streams of information, such as sensory, pre-motor, and reward-related inputs, to regulate local plasticity in MOp, we performed monosynaptic rabies tracing experiments and employed an automated cell counting pipeline to generate a comprehensive map of brain-wide inputs to VIP-INs in MOp. We then compared this input profile to the brain-wide inputs to somatostatin-expressing inhibitory interneurons (SST-INs) and parvalbumin-expressing inhibitory interneurons (PV-INs) in MOp. We found that while all cell types received major inputs from sensory, motor, and prefrontal cortical regions, as well as from various thalamic nuclei, VIP-INs received more inputs from the orbital frontal cortex (ORB) - a region associated with reinforcement learning and value predictions. Our findings provide insight on how the brain leverages microcircuit motifs by both integrating and partitioning different streams of long-range input to modulate local circuit activity and plasticity.

Human Timeless and Tipin stabilize replication forks and facilitate sister-chromatid cohesion.

The Timeless-Tipin protein complex has been reported to be important for replication checkpoint and normal DNA replication processes. However, the precise mechanisms by which Timeless-Tipin preserves genomic integrity are largely unclear. Here, we describe the roles of Timeless-Tipin in replication fork stabilization and sister chromatid cohesion. We show in human cells that Timeless is recruited to replication origin regions and dissociate from them as replication proceeds. Cdc45, which is known to be required for replication fork progression, shows similar patterns of origin association to those of Timeless. Depletion of Timeless-Tipin causes chromosome fragmentation and defects in damage repair in response to fork collapse, suggesting that it is required for replication fork maintenance under stress. We also demonstrate that depletion of Timeless-Tipin impairs sister chromatid cohesion and causes a defect in mitotic progression. Consistently, Timeless-Tipin co-purifies with cohesin subunits and is required for their stable association with chromatin during S phase. Timeless associates with the cohesion-promoting DNA helicase ChlR1, which, when overexpressed, partially alleviates the cohesion defect of cells depleted of Timeless-Tipin. These results suggest that Timeless-Tipin functions as a replication fork stabilizer that couples DNA replication with sister chromatid cohesion established at replication forks.

Cell-type-specific responses to associative learning in the primary motor cortex.

The primary motor cortex (M1) is known to be a critical site for movement initiation and motor learning. Surprisingly, it has also been shown to possess reward-related activity, presumably to facilitate reward-based learning of new movements. However, whether reward-related signals are represented among different cell types in M1, and whether their response properties change after cue-reward conditioning remains unclear. Here, we performed longitudinal in vivo two-photon Ca2+ imaging to monitor the activity of different neuronal cell types in M1 while mice engaged in a classical conditioning task. Our results demonstrate that most of the major neuronal cell types in M1 showed robust but differential responses to both the conditioned cue stimulus (CS) and reward, and their response properties undergo cell-type-specific modifications after associative learning. PV-INs' responses became more reliable to the CS, while VIP-INs' responses became more reliable to reward. Pyramidal neurons only showed robust responses to novel reward, and they habituated to it after associative learning. Lastly, SOM-INs' responses emerged and became more reliable to both the CS and reward after conditioning. These observations suggest that cue- and reward-related signals are preferentially represented among different neuronal cell types in M1, and the distinct modifications they undergo during associative learning could be essential in triggering different aspects of local circuit reorganization in M1 during reward-based motor skill learning.

Successful Concomitant Pulmonary Thromboendarterectomy and Heart Transplant.

Heart transplantation remains the gold standard of therapy for patients with end-stage heart failure. Submassive pulmonary embolism in a patient with heart failure is generally considered a contraindication to immediate heart transplantation, given the risk of right heart failure posttransplant. Generally patients must wait for extended periods of time to recover from pulmonary embolism therapies before being listed for transplant. We report a case of successful concomitant pulmonary thromboendarterectomy and heart transplantation.

Uncovering the Sex-Specific Endocrine Responses to Reproduction and Parental Care.

Hormones mediate physiological and behavioral changes in adults as they transition into reproduction. In this study, we characterize the circulating levels of five key hormones involved in reproduction in rock doves (Columba livia): corticosterone, progesterone, estradiol, testosterone, and prolactin using univariate and multivariate approaches. We show similar patterns as previous studies in the overall patterns in circulating levels of these hormones, i.e., testosterone (males) and estradiol (females) high during nest-building or egg-laying, prolactin increasing at mid-incubation and peaking at hatching (both sexes), and elevated corticosterone levels in later incubation and early nestling development. In our investigation of hormone co-variation, we find a strong correlation between prolactin and corticosterone across sampling stages and similarities in earlier (early to mid-incubation) compared to later (late incubation to nestling d9) sampling stages in males and females. Finally, we utilized experimental manipulations to simulate nest loss or altered caregiving lengths to test whether external cues, internal timing, or a combination of these factors contributed most to hormone variation. Following nest loss, we found that both males and females responded to the external cue. Males generally responded quickly following nest loss by increasing circulating testosterone, but this response was muted when nest loss occurred early in reproduction. Similar treatment type, e.g., removal of eggs, clustered similarly in hormone space. These results suggest internal drivers limited male response early in reproduction to nest loss. In contrast, circulating levels of these hormones in females either did not change or decreased following nest manipulation suggesting responsiveness to external drivers, but unlike males, this result suggests that reproductive processes were decreasing.

Light Up the Brain: The Application of Optogenetics in Cell-Type Specific Dissection of Mouse Brain Circuits.

The exquisite intricacies of neural circuits are fundamental to an animal's diverse and complex repertoire of sensory and motor functions. The ability to precisely map neural circuits and to selectively manipulate neural activity is critical to understanding brain function and has, therefore been a long-standing goal for neuroscientists. The recent development of optogenetic tools, combined with transgenic mouse lines, has endowed us with unprecedented spatiotemporal precision in circuit analysis. These advances greatly expand the scope of tractable experimental investigations. Here, in the first half of the review, we will present applications of optogenetics in identifying connectivity between different local neuronal cell types and of long-range projections with both in vitro and in vivo methods. We will then discuss how these tools can be used to reveal the functional roles of these cell-type specific connections in governing sensory information processing, and learning and memory in the visual cortex, somatosensory cortex, and motor cortex. Finally, we will discuss the prospect of new optogenetic tools and how their application can further advance modern neuroscience. In summary, this review serves as a primer to exemplify how optogenetics can be used in sophisticated modern circuit analyses at the levels of synapses, cells, network connectivity and behaviors.

Neural activity in a hippocampus-like region of the teleost pallium is associated with active sensing and navigation.

Most vertebrates use active sensing strategies for perception, cognition and control of motor activity. These strategies include directed body/sensor movements or increases in discrete sensory sampling events. The weakly electric fish, Gymnotus sp., uses its active electric sense during navigation in the dark. Electric organ discharge rate undergoes transient increases during navigation to increase electrosensory sampling. Gymnotus also use stereotyped backward swimming as an important form of active sensing that brings objects toward the electroreceptor dense fovea-like head region. We wirelessly recorded neural activity from the pallium of freely swimming Gymnotus. Spiking activity was sparse and occurred only during swimming. Notably, most units tended to fire during backward swims and their activity was on average coupled to increases in sensory sampling. Our results provide the first characterization of neural activity in a hippocampal (CA3)-like region of a teleost fish brain and connects it to active sensing of spatial environmental features.

A Randomized Controlled Trial of Liposomal Bupivacaine Parasternal Intercostal Block for Sternotomy.

BACKGROUND: Optimal pain control continues to be a concern in cardiac surgery. Current strategies for postoperative pain management often yield suboptimal results. The superiority of Exparel (Pacira Pharmaceuticals, Inc, Parsippany, NJ) in providing postoperative pain control and opioid sparing is equivocal. This prospective, randomized, double-blind study examines the efficacy of Exparel as a novel single-dose application parasternal nerve block in postoperative pain control and opioid sparing. METHODS: This single-surgeon study included 79 patients undergoing median sternotomy for coronary revascularization. Study participants were randomized to either the drug or a control arm. Each participant received Exparel or normal saline placebo administered as a parasternal nerve block. Postoperative pain was rated according to the nonverbal pain scale or numeric rating scale. Total amount of narcotic pain medication used and patients' pain scores within the first 72 hours postoperatively were compared. Secondary outcomes compared the intensive care unit length of stay, hospital length of stay, time to extubation, time to return of bowel function, and time to return to work or daily activities. RESULTS: The primary endpoint of pain levels between the two groups demonstrated no significant difference when analyzing the individual time points postoperatively. However, overall pain levels were significantly lower in the study drug group (p = 0.04). There was no significant difference in the amount of analgesics required postoperatively or in secondary endpoints between the groups. CONCLUSIONS: Exparel does not provide an opioid-sparing benefit or any secondary outcome benefit compared with placebo. Exparel may be associated with a marginal decrease in postoperative pain levels. (Parasternal Nerve Bock in Cardiac Patients; NCT01826851.).

Comparison of Automated Titanium Fasteners to Hand-Tied Knots in Open Aortic Valve Replacement.

OBJECTIVE: Aortic cross-clamp and cardiopulmonary bypass times are independent predictors of postoperative morbidity and mortality. Reducing ischemic times with automated titanium fasteners may improve surgical outcomes. This study compared operative times and costs of titanium fasteners versus hand-tied knots for prosthesis securement in open aortic valve replacement. METHODS: A randomized control trial was conducted during a 16-month period at a single university medical center. Patients undergoing elective aortic valve replacement were randomized to the titanium fastener (n = 37) or hand-tied groups (n = 36). Knotting, aortic cross-clamp, cardiopulmonary bypass, and total operating room times were recorded. Hospital charges were also calculated for these procedures. RESULTS: Baseline characteristics, concomitant procedures, prosthetic valve size, and sutures were similar between groups. The titanium fastener group had significantly reduced knotting (7.4 vs. 13.0 minutes, P < 0.001), aortic cross-clamp (69 vs. 90 minutes, P < 0.05), cardiopulmonary bypass (86 vs. 114 minutes, P < 0.05), and total operating room times (234 vs. 266 minutes, P < 0.05). Intraoperative complications occurred more frequently in the hand-tied group compared with the titanium fastener group. Postoperative complications were similar between groups. Operating room costs were significantly higher in the titanium fastener group (US $10,428 vs. US $9671, P = 0.01). Hospitalization costs did not differ significantly between the titanium fastener and hand-tied group (US $23,987 vs. US $21,068, P = 0.12). CONCLUSIONS: Titanium fastener use was associated with shorter knotting, aortic cross-clamp, cardiopulmonary bypass, and operating room times and fewer intraoperative complications in open aortic valve replacement, without significantly increasing hospitalization cost.

An Automated Expanded Polytetrafluoroethylene Suturing and Coaxial Fastener System for Mitral Chordae Replacement: Strength, Feasibility, and Healing.

OBJECTIVE: Mitral valve (MV) chordae replacements can be technically challenging. Technology that remotely delivers and accurately secures artificial chordae may reduce the learning curve and improve the reliability of MV repairs. METHODS: The technology involved two devices: a remote suturing device for delivery of expanded polytetrafluoroethylene (ePTFE) suture to the papillary muscle and a Coaxial titanium suture fastener (TF) device with integrated saline infusion for real-time determination of chordae length during fixation. A mechanical model simulating MV chordae tension in a beating heart quantified the durability of 120 coaxially fastened ePTFE sutures using TF over time. Investigation of the technology was performed in ex vivo porcine, ovine, and in situ cadaver hearts, whereas live-tissue testing was conducted in a survivor ovine model. Mitral valve repair procedures involved the iatrogenic induction of mitral regurgitation by the resection of one to two native MV chordae, followed by implantation of ePTFE suture using the technology. Epicardial echocardiography, saline infusion testing, and histologic analysis evaluated MV competence, repair integrity, and long-term healing. RESULTS: Durability testing of ePTFE suture secured with TF demonstrated no degradation of TF pull-apart forces of for 440 million cycles. Mitral valve repairs using the technology were performed in eight sheep; four demonstrating proof of concept and four survived for an average of 6.5 months after completion of the procedure. At reoperation, echocardiography demonstrated trace to no mitral regurgitation with near complete endothelialization of the TF and artificial chordae. CONCLUSIONS: This technology successfully enabled the implantation of artificial chordae while providing real-time adjustment of chordae length during MV repair. These results encourage further investigation of its use clinically.