Sleep need-dependent changes in functional connectivity facilitate transmission of homeostatic sleep drive.

How the homeostatic drive for sleep accumulates over time and is released remains poorly understood. In Drosophila, we previously identified the R5 ellipsoid body (EB) neurons as putative sleep drive neurons1 and recently described a mechanism by which astrocytes signal to these cells to convey sleep need.2 Here, we examine the mechanisms acting downstream of the R5 neurons to promote sleep. EM connectome data demonstrate that R5 neurons project to EPG neurons.3 Broad thermogenetic activation of EPG neurons promotes sleep, whereas inhibiting these cells reduces homeostatic sleep rebound. Perforated patch-clamp recordings reveal that EPG neurons exhibit elevated spontaneous firing following sleep deprivation, which likely depends on an increase in extrinsic excitatory inputs. Our data suggest that cholinergic R5 neurons participate in the homeostatic regulation of sleep, and epistasis experiments indicate that the R5 neurons act upstream of EPG neurons to promote sleep. Finally, we show that the physical and functional connectivity between the R5 and EPG neurons increases with greater sleep need. Importantly, dual patch-clamp recordings demonstrate that activating R5 neurons induces cholinergic-dependent excitatory postsynaptic responses in EPG neurons. Moreover, sleep loss triggers an increase in the amplitude of these responses, as well as in the proportion of EPG neurons that respond. Together, our data support a model whereby sleep drive strengthens the functional connectivity between R5 and EPG neurons, triggering sleep when a sufficient number of EPG neurons are activated. This process could enable the proper timing of the accumulation and release of sleep drive.

Procedural, Short-Term, and Intermediate-Term Outcomes in Propensity-Matched Patients With Severe Mitral Valve Regurgitation Undergoing Urgent Versus Elective MitraClip Percutaneous Mitral Valve Repair.

OBJECTIVE: The study authors sought to compare outcomes in patients with severe mitral valve regurgitation (MR) undergoing urgent, as compared to elective, mitral valve repair employing MitraClip. They hypothesized that, compared to elective cases, MitraClip procedures performed for urgent indications would be associated with increased intraoperative and postoperative complications but have similar long-term outcomes. DESIGN: A retrospective chart review with 3:1 propensity score matching of elective-to-urgent cases. SETTING: A single, large-volume tertiary care academic medical center. PARTICIPANTS: All consecutive patients with severe MR who underwent elective or urgent MitraClip procedures between December 15, 2015, and October 26, 2020. INTERVENTIONS: MR repair with MitraClip. MEASUREMENTS AND MAIN RESULTS: As expected, patients in the urgent MitraClip group required a higher level of preprocedural care, and there were significant differences in baseline demographic and clinical variables as compared to the elective group. To reduce baseline characteristics heterogeneity, propensity matching was performed for age, left ventricular systolic dysfunction, congestive heart failure, chronic obstructive pulmonary disease, and smoking histories, using the nearest-neighbor matching with a caliper of 0.2 and with replacement. The final study cohort included 89 urgent and 252 matched elective cases, with a suitable alignment between the treatment groups. Propensity-matched urgent MitraClip patients experienced a longer hospital length of stay (p < 0.001), increased intensive care unit admissions (19% v 4%, p < 0.001) and mechanical ventilation (6.7% v 1.6%, p = 0.023), postprocedural atrial fibrillation (11% v 4.4%, p = 0.036), pericardial effusion (10% v 2.4%, p = 0.005), and acute kidney injury (7.9% v 2%, p = 0.016). Furthermore, patients in the urgent cohort incurred significantly higher 30-day cardiovascular mortality (6.7% v 2%, p = 0.039), increased 30-day (16% v 5.6%, p = 0.006), and 1-year (33% v 20%, p = 0.021) readmission rates. However, there were no statistically significant differences in 30-day and 1-year overall and 1-year cardiovascular mortality. CONCLUSIONS: Urgent MitraClip repairs can be performed successfully, when needed, in critically ill patients with severe MR. Despite the procedural success, patients undergoing urgent MitraClip repair remain at high risk for adverse outcomes in the short- and intermediate-term and incur increased cardiovascular mortality and morbidity. Further efforts are required to develop strategies to optimize short and intermediate outcomes in this vulnerable group of patients.

Astroglial Calcium Signaling Encodes Sleep Need in Drosophila.

Sleep is under homeostatic control, whereby increasing wakefulness generates sleep need and triggers sleep drive. However, the molecular and cellular pathways by which sleep need is encoded are poorly understood. In addition, the mechanisms underlying both how and when sleep need is transformed to sleep drive are unknown. Here, using ex vivo and in vivo imaging, we show in Drosophila that astroglial Ca2+ signaling increases with sleep need. We demonstrate that this signaling is dependent on a specific L-type Ca2+ channel and is necessary for homeostatic sleep rebound. Thermogenetically increasing Ca2+ in astrocytes induces persistent sleep behavior, and we exploit this phenotype to conduct a genetic screen for genes required for the homeostatic regulation of sleep. From this large-scale screen, we identify TyrRII, a monoaminergic receptor required in astrocytes for sleep homeostasis. TyrRII levels rise following sleep deprivation in a Ca2+-dependent manner, promoting further increases in astrocytic Ca2+ and resulting in a positive-feedback loop. Moreover, our findings suggest that astrocytes then transmit this sleep need to a sleep drive circuit by upregulating and releasing the interleukin-1 analog Spätzle, which then acts on Toll receptors on R5 neurons. These findings define astroglial Ca2+ signaling mechanisms encoding sleep need and reveal dynamic properties of the sleep homeostatic control system.

Response to Placebo in Fragile X Syndrome Clinical Trials: An Initial Analysis.

Fragile X syndrome (FXS) is the leading cause of inherited intellectual disability and autism spectrum disorder. Individuals with FXS often present with a wide range of cognitive deficits and problem behaviors. Educational, behavioral and pharmacological interventions are used to manage these and other complex issues affecting individuals with FXS. Despite the success of preclinical models and early-phase drug clinical studies in FXS, large-scale randomized-controlled trials have failed to meet primary endpoints. Currently, no targeted or disease-modifying treatments for FXS have received regulatory approval. Here, we examined the placebo response in FXS clinical trials conducted between 2006 and 2018. Specifically, we performed a meta-analysis of placebo-treated groups in eight double-blind, randomized controlled trials. Placebo groups demonstrated significant improvements on caregiver-rated efficacy endpoints, which were greater in adolescents and adults than in children. Among the latter measures, the Visual Analog Scale scores displayed the greatest improvements, whereas the positive effects on the Vineland-II Adaptive Behavior Composite and the Aberrant Behavior Checklist-Community/fragile X version were statistically significant in both children and adolescents/adults. Although the Clinical Global Impression scale Improvement appears to have exhibited a substantial placebo effect in multiple clinical trials in FXS, limited data availability for meta-analysis, prevented us from drawing conclusions. No placebo-related improvements were observed in performance-rated measures. These findings raise substantial concerns about placebo effects in outcome measures commonly used in the randomized-controlled trials in FXS and suggest several potential improvements in the study design and implementation of such trials. Considering the small number of trials available for this study, larger and more detailed follow up meta-analyses are needed. Meanwhile, efforts to improve the measurement properties of endpoints and rater training in drug trials in FXS should be prioritized.