A Regulatory Circuit Controlling the Dynamics of NFκB cRel Transitions B Cells from Proliferation to Plasma Cell Differentiation.

Humoral immunity depends on efficient activation of B cells and their subsequent differentiation into antibody-secreting cells (ASCs). The transcription factor NFκB cRel is critical for B cell proliferation, but incorporating its known regulatory interactions into a mathematical model of the ASC differentiation circuit prevented ASC generation in simulations. Indeed, experimental ectopic cRel expression blocked ASC differentiation by inhibiting the transcription factor Blimp1, and in wild-type (WT) cells cRel was dynamically repressed during ASC differentiation by Blimp1 binding the Rel locus. Including this bi-stable circuit of mutual cRel-Blimp1 antagonism into a multi-scale model revealed that dynamic repression of cRel controls the switch from B cell proliferation to ASC generation phases and hence the respective cell population dynamics. Our studies provide a mechanistic explanation of how dysregulation of this bi-stable circuit might result in pathologic B cell population phenotypes and thus offer new avenues for diagnostic stratification and treatment.

Logged tropical forests have amplified and diverse ecosystem energetics.

Old-growth tropical forests are widely recognized as being immensely important for their biodiversity and high biomass1. Conversely, logged tropical forests are usually characterized as degraded ecosystems2. However, whether logging results in a degradation in ecosystem functions is less clear: shifts in the strength and resilience of key ecosystem processes in large suites of species have rarely been assessed in an ecologically integrated and quantitative framework. Here we adopt an ecosystem energetics lens to gain new insight into the impacts of tropical forest disturbance on a key integrative aspect of ecological function: food pathways and community structure of birds and mammals. We focus on a gradient spanning old-growth and logged forests and oil palm plantations in Borneo. In logged forest there is a 2.5-fold increase in total resource consumption by both birds and mammals compared to that in old-growth forests, probably driven by greater resource accessibility and vegetation palatability. Most principal energetic pathways maintain high species diversity and redundancy, implying maintained resilience. Conversion of logged forest into oil palm plantation results in the collapse of most energetic pathways. Far from being degraded ecosystems, even heavily logged forests can be vibrant and diverse ecosystems with enhanced levels of ecological function.

Support-vector classification of low-dose nitrous oxide administration with multi-channel EEG power spectra.

Support-vector machines (SVMs) can potentially improve patient monitoring during nitrous oxide anaesthesia. By elucidating the effects of low-dose nitrous oxide on the power spectra of multi-channel EEG recordings, we quantified the degree to which these effects generalise across participants. In this single-blind, cross-over study, 32-channel EEG was recorded from 12 healthy participants exposed to 0, 20, 30 and 40% end-tidal nitrous oxide. Features of the delta-, theta-, alpha- and beta-band power were used within a 12-fold, participant-wise cross-validation framework to train and test two SVMs: (1) binary SVM classifying EEG during 0 or 40% exposure (chance = 50%); (2) multi-class SVM classifying EEG during 0, 20, 30 or 40% exposure (chance = 25%). Both the binary (accuracy 92%) and the multi-class (accuracy 52%) SVMs classified EEG recordings at rates significantly better than chance (p < 0.001 and p = 0.01, respectively). To determine the relative importance of frequency band features for classification accuracy, we systematically removed features before re-training and re-testing the SVMs. This showed the relative importance of decreased delta power and the frontal region. SVM classification identified that the most important effects of nitrous oxide were found in the delta band in the frontal electrodes that was consistent between participants. Furthermore, support-vector classification of nitrous oxide dosage is a promising method that might be used to improve patient monitoring during nitrous oxide anaesthesia.

TLR9 expression in chronic lymphocytic leukemia identifies a promigratory subpopulation and novel therapeutic target.

Chronic lymphocytic leukemia (CLL) remains incurable despite B-cell receptor-targeted inhibitors revolutionizing treatment. This suggests that other signaling molecules are involved in disease escape mechanisms and resistance. Toll-like receptor 9 (TLR9) is a promising candidate that is activated by unmethylated cytosine guanine dinucleotide-DNA. Here, we show that plasma from patients with CLL contains significantly more unmethylated DNA than plasma from healthy control subjects (P < .0001) and that cell-free DNA levels correlate with the prognostic markers CD38, ß2-microglobulin, and lymphocyte doubling time. Furthermore, elevated cell-free DNA was associated with shorter time to first treatment (hazard ratio, 4.0; P = .003). We also show that TLR9 expression was associated with in vitro CLL cell migration (P < .001), and intracellular endosomal TLR9 strongly correlated with aberrant surface expression (sTLR9; r = 0.9). In addition, lymph node-derived CLL cells exhibited increased sTLR9 (P = .016), and RNA-sequencing of paired sTLR9hi and sTLR9lo CLL cells revealed differential transcription of genes involved in TLR signaling, adhesion, motility, and inflammation in sTLR9hi cells. Mechanistically, a TLR9 agonist, ODN2006, promoted CLL cell migration (P < .001) that was mediated by p65 NF-κB and STAT3 transcription factor activation. Importantly, autologous plasma induced the same effects, which were reversed by a TLR9 antagonist. Furthermore, high TLR9 expression promoted engraftment and rapid disease progression in a NOD/Shi-scid/IL-2Rγnull mouse xenograft model. Finally, we showed that dual targeting of TLR9 and Bruton's tyrosine kinase (BTK) was strongly synergistic (median combination index, 0.2 at half maximal effective dose), which highlights the distinct role for TLR9 signaling in CLL and the potential for combined targeting of TLR9 and BTK as a more effective treatment strategy in this incurable disease.

A prospective observational study on the effect of emboli exposure on cerebral autoregulation in cardiac surgery requiring cardiopulmonary bypass.

OBJECTIVE: Cerebrovascular autoregulation impairment has been associated with stroke risk in cardiac surgery. We hypothesized that greater arterial emboli exposure in open-chamber surgery might promote dysautoreguation. METHODS: Forty patients underwent closed or open-chamber surgery. Transcranial Doppler detected emboli and measured bilateral middle cerebral artery flow velocities. Cerebral autoregulation was assessed by averaging the mean velocity index ("Mx," a continuous moving correlation between cerebral blood flow velocity and mean arterial pressure) over 30 min before and after aortic cross-clamp removal. RESULTS: Median (interquartile range) emboli counts were 775 (415, 1211) and 2664 (793, 3734) in the closed-chamber and open-chamber groups. Most appeared after the removal of the aortic cross-clamp (open-chamber 1631 (606, 2296)), (closed-chamber 229 (142, 384)), with emphasis on the right hemisphere (open-chamber: 826 (371, 1622)), (closed-chamber 181 (66, 276)). Linear mixed model analyses of mean velocity index change showed no significant overall effect of group (0.08, 95% CI: -0.04, 0.21; p = 0.19) or side (0.01, 95% CI: -0.03, 0.05; p = 0.74). There was an interaction between group and side (p = 0.001), manifesting as a greater increase in mean velocity index in the right hemisphere in the open than the closed group (mean difference: 0.15, 95% CI: 0.02, 0.27; p = 0.03). CONCLUSIONS: Overall, change in mean velocity index before and after cross-clamp removal did not differ between groups. However, most emboli entered the right cerebral hemisphere where this change was significantly greater in the open-chamber group, suggesting a possible association between embolic exposure and dysautoregulation.

Safeguarding Imperiled Biodiversity and Evolutionary Processes in the Wallacea Center of Endemism.

Wallacea-the meeting point between the Asian and Australian fauna-is one of the world's largest centers of endemism. Twenty-three million years of complex geological history have given rise to a living laboratory for the study of evolution and biodiversity, highly vulnerable to anthropogenic pressures. In the present article, we review the historic and contemporary processes shaping Wallacea's biodiversity and explore ways to conserve its unique ecosystems. Although remoteness has spared many Wallacean islands from the severe overexploitation that characterizes many tropical regions, industrial-scale expansion of agriculture, mining, aquaculture and fisheries is damaging terrestrial and aquatic ecosystems, denuding endemics from communities, and threatening a long-term legacy of impoverished human populations. An impending biodiversity catastrophe demands collaborative actions to improve community-based management, minimize environmental impacts, monitor threatened species, and reduce wildlife trade. Securing a positive future for Wallacea's imperiled ecosystems requires a fundamental shift away from managing marine and terrestrial realms independently.

Dissecting the impact of bromodomain inhibitors on the Interferon Regulatory Factor 4-MYC oncogenic axis in multiple myeloma.

B-cell progenitor fate determinant interferon regulatory factor 4 (IRF4) exerts key roles in the pathogenesis and progression of multiple myeloma (MM), a currently incurable plasma cell malignancy. Aberrant expression of IRF4 and the establishment of a positive auto-regulatory loop with oncogene MYC, drives a MM specific gene-expression program leading to the abnormal expansion of malignant immature plasma cells. Targeting the IRF4-MYC oncogenic loop has the potential to provide a selective and effective therapy for MM. Here we evaluate the use of bromodomain inhibitors to target the IRF4-MYC axis through combined inhibition of their known epigenetic regulators, BRD4 and CBP/EP300. Although all inhibitors induced cell death, we found no synergistic effect of targeting both of these regulators on the viability of MM cell-lines. Importantly, for all inhibitors over a time period up to 72 h, we detected reduced IRF4 mRNA, but a limited decrease in IRF4 protein expression or mRNA levels of downstream target genes. This indicates that inhibitor-induced loss of cell viability is not mediated through reduced IRF4 protein expression, as previously proposed. Further analysis revealed a long half-life of IRF4 protein in MM cells. In support of our experimental observations, gene network modeling of MM suggests that bromodomain inhibition is exerted primarily through MYC and not IRF4. These findings suggest that despite the autofeedback positive regulatory loop between IRF4 and MYC, bromodomain inhibitors are not effective at targeting IRF4 in MM and that novel therapeutic strategies should focus on the direct inhibition or degradation of IRF4.

Substrate complex competition is a regulatory motif that allows NFκB RelA to license but not amplify NFκB RelB.

Signaling pathways often share molecular components, tying the activity of one pathway to the functioning of another. In the NFκB signaling system, distinct kinases mediate inflammatory and developmental signaling via RelA and RelB, respectively. Although the substrates of the developmental, so-called noncanonical, pathway are induced by inflammatory/canonical signaling, crosstalk is limited. Through dynamical systems modeling, we identified the underlying regulatory mechanism. We found that as the substrate of the noncanonical kinase NIK, the nfkb2 gene product p100, transitions from a monomer to a multimeric complex, it may compete with and inhibit p100 processing to the active p52. Although multimeric complexes of p100 (IκBδ) are known to inhibit preexisting RelA:p50 through sequestration, here we report that p100 complexes can inhibit the enzymatic formation of RelB:p52. We show that the dose-response systems properties of this complex substrate competition motif are poorly accounted for by standard Michaelis-Menten kinetics, but require more detailed mass action formulations. In sum, although tonic inflammatory signaling is required for adequate expression of the noncanonical pathway precursors, the substrate complex competition motif identified here can prevent amplification of the active RelB:p52 dimer in elevated inflammatory conditions to ensure reliable RelB-dependent developmental signaling independent of inflammatory context.

A prospective observational study of emboli exposure in open versus closed chamber cardiac surgery.

OBJECTIVE: Exposure to cerebral emboli is ubiquitous and may be harmful in cardiac surgery utilizing cardiopulmonary bypass. This was a prospective observational study aiming to compare emboli exposure in closed-chamber with open-chamber cardiac surgery, distinguish particulate from gaseous emboli and examine cerebral laterality in distribution. METHODS: Forty patients underwent either closed-chamber procedures (n = 20) or open-chamber procedures (n = 20). Emboli (gaseous and solid) were detected using transcranial Doppler in both middle cerebral arteries in two monitoring phases: 1, initiation of bypass to the removal of the aortic cross-clamp; and 2, removal of aortic cross-clamp to 20 minutes after venous decannulation. RESULTS: Total (median (interquartile range)) emboli counts (both phases) were 898 (499-1366) and 2617 (1007-5847) in closed-chamber and open-chamber surgeries, respectively. The vast majority were gaseous; median 794 (closed-chamber surgery) and 2240 (open-chamber surgery). When normalized for duration, there was no difference between emboli exposures in closed-chamber and open-chamber surgery in phase 1: 6.8 (3.6-15.2) versus 6.4 (2.0-18.1) emboli per minute, respectively. In phase 2, closed-chamber surgery cases were exposed to markedly fewer emboli than open-chamber surgery cases: 9.6 (5.1-14.9) versus 43.3 (19.7-60.3) emboli per minute, respectively. More emboli (total) passed into the right cerebral circulation: 985 (397-2422) right versus 376 (198-769) left. CONCLUSIONS: Patients undergoing open-chamber surgery are exposed to considerably higher numbers of cerebral arterial emboli after removal of the aortic cross-clamp than those undergoing closed-chamber surgery, and more emboli enter the right middle cerebral artery than the left. These results may help inform the evaluation of the pathophysiological impact of emboli exposure.

Comment on Mankowska et al. Critical Flicker Fusion Frequency: A Narrative Review. Medicina 2021, 57, 1096.

We have read with great interest the review by Mankowska et al. [...].

An incoherent feedforward loop interprets NFκB/RelA dynamics to determine TNF-induced necroptosis decisions.

Balancing cell death is essential to maintain healthy tissue homeostasis and prevent disease. Tumor necrosis factor (TNF) not only activates nuclear factor κB (NFκB), which coordinates the cellular response to inflammation, but may also trigger necroptosis, a pro-inflammatory form of cell death. Whether TNF-induced NFκB affects the fate decision to undergo TNF-induced necroptosis is unclear. Live-cell microscopy and model-aided analysis of death kinetics identified a molecular circuit that interprets TNF-induced NFκB/RelA dynamics to control necroptosis decisions. Inducible expression of TNFAIP3/A20 forms an incoherent feedforward loop to interfere with the RIPK3-containing necrosome complex and protect a fraction of cells from transient, but not long-term TNF exposure. Furthermore, dysregulated NFκB dynamics often associated with disease diminish TNF-induced necroptosis. Our results suggest that TNF's dual roles in either coordinating cellular responses to inflammation, or further amplifying inflammation are determined by a dynamic NFκB-A20-RIPK3 circuit, that could be targeted to treat inflammation and cancer.

The Effect of Clozapine on Self-reported Duration of Sleep and Its Interaction With 23 Other Medications: A 5-Year Naturalistic Study.

BACKGROUND: Sedation is a common and incapacitating clozapine adverse effect, but the factors associated with sedation and its pharmacological management remain poorly studied. METHODS: We conducted a retrospective cohort study based on deidentified electronic clinical records of clozapine-treated patients from the secondary mental health care provider for Cambridgeshire and Peterborough, United Kingdom. We first evaluated cross-sectionally the influence of clozapine dose, clozapine, and norclozapine plasma levels on self-reported hours slept, as a proxy for sedation, using bivariate correlation and then the longitudinal effect of changes in clozapine dose and other 23 medications using linear mixed effect models. We followed 241 clozapine-treated patients for 56 months on average, with 2237 face-to-face assessments in total. RESULTS: Patients slept for a mean of 9.35 h/d, with 46% reporting 10 h/d or more. Cross-sectionally, sleep duration did not correlate with clozapine dose (r = 0.14, P = 0.106), but with clozapine plasma levels (r = 0.38, P < 0.0001) and norclozapine plasma levels (r = 0.25, P = 0.005). Longitudinally, the final mixed-effects model revealed 4 pharmacological variables that had a significant impact on hours slept: clozapine, risperidone augmentation, and atenolol were associated with increased sleep, whereas aripiprazole augmentation was associated with decreased sleep. We found that 20 other psychotropic medications measured were not associated with changes in sleep when added to clozapine. Excess sleep is a clozapine level-dependent adverse effect. CONCLUSIONS: The impact of different augmentation strategies might help clinicians decide on the most adequate strategy, albeit further studies should confirm our results.

An Electroencephalogram Metric of Temporal Complexity Tracks Psychometric Impairment Caused by Low-dose Nitrous Oxide.

BACKGROUND: Nitrous oxide produces non-γ-aminobutyric acid sedation and psychometric impairment and can be used as scientific model for understanding mechanisms of progressive cognitive disturbances. Temporal complexity of the electroencephalogram may be a sensitive indicator of these effects. This study measured psychometric performance and the temporal complexity of the electroencephalogram in participants breathing low-dose nitrous oxide. METHODS: In random order, 20, 30, and 40% end-tidal nitrous oxide was administered to 12 participants while recording 32-channel electroencephalogram and psychometric function. A novel metric quantifying the spatial distribution of temporal electroencephalogram complexity, comprised of (1) absolute cross-correlation calculated between consecutive 0.25-s time samples; 2) binarizing these cross-correlation matrices using the median of all channels as threshold; (3) using quantitative recurrence analysis, the complexity in temporal changes calculated by the Shannon entropy of the probability distribution of the diagonal line lengths; and (4) overall spatial extent and intensity of brain complexity, was quantified by calculating median temporal complexity of channels whose complexities were above 1 at baseline. This region approximately overlay the brain's default mode network, so this summary statistic was termed "default-mode-network complexity." RESULTS: Nitrous oxide concentration correlated with psychometric impairment (r = 0.50, P < 0.001). Baseline regional electroencephalogram complexity at midline was greater than in lateral temporal channels (1.33 ± 0.14 bits vs. 0.81 ± 0.12 bits, P < 0.001). A dose of 40% N2O decreased midline (mean difference [95% CI], 0.20 bits [0.09 to 0.31], P = 0.002) and prefrontal electroencephalogram complexity (mean difference [95% CI], 0.17 bits [0.08 to 0.27], P = 0.002). The lateral temporal region did not change significantly (mean difference [95% CI], 0.14 bits [-0.03 to 0.30], P = 0.100). Default-mode-network complexity correlated with N2O concentration (r = -0.55, P < 0.001). A default-mode-network complexity mixed-effects model correlated with psychometric impairment (r2 = 0.67; receiver operating characteristic area [95% CI], 0.72 [0.59 to 0.85], P < 0.001). CONCLUSIONS: Temporal complexity decreased most markedly in medial cortical regions during low-dose nitrous oxide exposures, and this change tracked psychometric impairment.

Neuronal Network Topology Indicates Distinct Recovery Processes after Stroke.

Despite substantial recent progress in network neuroscience, the impact of stroke on the distinct features of reorganizing neuronal networks during recovery has not been defined. Using a functional connections-based approach through 2-photon in vivo calcium imaging at the level of single neurons, we demonstrate for the first time the functional connectivity maps during motion and nonmotion states, connection length distribution in functional connectome maps and a pattern of high clustering in motor and premotor cortical networks that is disturbed in stroke and reconstitutes partially in recovery. Stroke disrupts the network topology of connected inhibitory and excitatory neurons with distinct patterns in these 2 cell types and in different cortical areas. These data indicate that premotor cortex displays a distinguished neuron-specific recovery profile after stroke.

Nongenetic origins of cell-to-cell variability in B lymphocyte proliferation.

Rapid antibody production in response to invading pathogens requires the dramatic expansion of pathogen-derived antigen-specific B lymphocyte populations. Whether B cell population dynamics are based on stochastic competition between competing cell fates, as in the development of competence by the bacterium Bacillus subtilis, or on deterministic cell fate decisions that execute a predictable program, as during the development of the worm Caenorhabditis elegans, remains unclear. Here, we developed long-term live-cell microscopy of B cell population expansion and multiscale mechanistic computational modeling to characterize the role of molecular noise in determining phenotype heterogeneity. We show that the cell lineage trees underlying B cell population dynamics are mediated by a largely predictable decision-making process where the heterogeneity of cell proliferation and death decisions at any given timepoint largely derives from nongenetic heterogeneity in the founder cells. This means that contrary to previous models, only a minority of genetically identical founder cells contribute the majority to the population response. We computationally predict and experimentally confirm nongenetic molecular determinants that are predictive of founder cells' proliferative capacity. While founder cell heterogeneity may arise from different exposure histories, we show that it may also be due to the gradual accumulation of small amounts of intrinsic noise during the lineage differentiation process of hematopoietic stem cells to mature B cells. Our finding of the largely deterministic nature of B lymphocyte responses may provide opportunities for diagnostic and therapeutic development.

Visualization of Intracranial Pressure Insults After Severe Traumatic Brain Injury: Influence of Individualized Limits of Reactivity.

Cerebral perfusion pressure (CPP) lower limits of reactivity can be determined almost continuously after severe traumatic brain injury (TBI), and deviation below the lower limit carries important prognostic information. In this study, we used a recently derived coloured contour method for visualizing intracranial pressure (ICP) insults to describe the influence of having a CPP above the CPP lower limits of reactivity after severe TBI. In a cohort of 729 patients, we examined the relationship between ICP insults and the 6-month Glasgow Outcome Scale score, using colour-coded plots, as described previously. We then assessed this relationship when ICP insults were above or below the CPP lower limit of reactivity. We found a curvilinear relationship whereby even prolonged durations of low-intensity ICP insults were not associated with poor outcomes but short durations of high-intensity insults were. When only ICP insults with a CPP below the CPP lower limit of reactivity were considered, a much lower intensity of ICP insults could be tolerated. A CPP above the lower limits of reactivity exerts a protective effect, whereas a CPP below the lower reactivity limits renders the patient vulnerable to increased morbidity from intracranial hypertension.

Polypyrimidine tract-binding protein blocks miRNA-124 biogenesis to enforce its neuronal-specific expression in the mouse.

MicroRNA (miRNA)-124 is expressed in neurons, where it represses genes inhibitory for neuronal differentiation, including the RNA binding protein PTBP1. PTBP1 maintains nonneuronal splicing patterns of mRNAs that switch to neuronal isoforms upon neuronal differentiation. We find that primary (pri)-miR-124-1 is expressed in mouse embryonic stem cells where mature miR-124 is absent. PTBP1 binds to this precursor RNA upstream of the miRNA stem-loop to inhibit mature miR-124 expression in vivo and DROSHA cleavage of pri-miR-124-1 in vitro. This function for PTBP1 in repressing miR-124 biogenesis defines an additional regulatory loop in the already intricate interplay between these two molecules. Applying mathematical modeling to examine the dynamics of this regulation, we find that the pool of pri-miR-124 whose maturation is blocked by PTBP1 creates a robust and self-reinforcing transition in gene expression as PTBP1 is depleted during early neuronal differentiation. While interlocking regulatory loops are often found between miRNAs and transcriptional regulators, our results indicate that miRNA targeting of posttranscriptional regulators also reinforces developmental decisions. Notably, induction of neuronal differentiation observed upon PTBP1 knockdown likely results from direct derepression of miR-124, in addition to indirect effects previously described.

Hyperbaric oxygen for decompression sickness.

Decompression sickness (DCS, "bends") is caused by formation of bubbles in tissues and/or blood when the sum of dissolved gas pressures exceeds ambient pressure (supersaturation). This may occur when ambient pressure is reduced during any of the following: ascent from a dive; depressurization of a hyperbaric chamber; rapid ascent to altitude in an unpressurized aircraft or hypobaric chamber; loss of cabin pressure in an aircraft; and during space walks.

Examining Collaborative Processes for Climate Change Adaptation in New Brunswick, Canada.

Collaboration is a proposed strategy to address super wicked environmental problems, such as climate change. Yet, understanding how it works for climate change adaptation is nascent. This research aims to advance the understanding of this by a cross-case analysis of three cases in New Brunswick, Canada. We sought to illuminate the inner workings of multiparty collaboration in the context of community climate change adaptation; identify important qualities of the process and outcomes from it, and probe their relationships; and, explore how they come about in practice. A questionnaire was sent to individuals involved in cases and key informant interviews were conducted. Results reveal case-specific variations, but more importantly, common qualities and outcomes across the cases. They offer key insight into elements which may be important in collaborative settings. These are informative for influencing the uptake of collaborative strategies in climate change adaptation and offer the opportunity to better understand their functional effectiveness.