Transient Reactivity Research Articles

5-Aza-2'-Deoxycytidine and Valproic Acid in Combination with CHIR99021 and A83-01 Induce Pluripotency Genes Expression in Human Adult Somatic Cells.

A generation of induced pluripotent stem cells (iPSC) by ectopic expression of OCT4, SOX2, KLF4, and c-MYC has established promising opportunities for stem cell research, drug discovery, and disease modeling. While this forced genetic expression represents an advantage, there will always be an issue with genomic instability and transient pluripotency genes reactivation that might preclude their clinical application. During the reprogramming process, a somatic cell must undergo several epigenetic modifications to induce groups of genes capable of reactivating the endogenous pluripotency core. Here, looking to increase the reprograming efficiency in somatic cells, we evaluated the effect of epigenetic molecules 5-aza-2′-deoxycytidine (5AZ) and valproic acid (VPA) and two small molecules reported as reprogramming enhancers, CHIR99021 and A83-01, on the expression of pluripotency genes and the methylation profile of the OCT4 promoter in a human dermal fibroblasts cell strain. The addition of this cocktail to culture medium increased the expression of OCT4, SOX2, and KLF4 expression by 2.1-fold, 8.5-fold, and 2-fold, respectively, with respect to controls; concomitantly, a reduction in methylated CpG sites in OCT4 promoter region was observed. The epigenetic cocktail also induced the expression of the metastasis-associated gene S100A4. However, the epigenetic cocktail did not induce the morphological changes characteristic of the reprogramming process. In summary, 5AZ, VPA, CHIR99021, and A83-01 induced the expression of OCT4 and SOX2, two critical genes for iPSC. Future studies will allow us to precise the mechanisms by which these compounds exert their reprogramming effects.

Nucleoside derivatives of 5-methylcytosine suppress 5-azacytidine-induced reactivation of a silent transgene in suspension-cultured tobacco cells.

Epigenetic modifications, including DNA methylation, are involved in the regulatory mechanisms of gene expression in animals and plants. In this study, we investigated whether the action of 5-azacytidine (5-aza-Cd), which is a well-known DNA methylation inhibitor, in suspension-cultured tobacco cells is affected by treatment with nucleoside derivatives of 5-methylcytosine (5-mCs), namely 5-methylcytidine (5-mCd) and 5-methyl-2'-deoxycytidine (5-mdCd). In a tobacco cell line, 5-aza-Cd treatment reactivated an epigenetically silenced transgene containing the cauliflower mosaic virus 35S promoter fused to the β-glucuronidase coding region and the nopaline synthase polyadenylation signal. The reactivation was evident on the fifth day of treatment and was augmented during culture with application of 5-aza-Cd at every subcultivation. This treatment, provided only once in the initial culture, resulted in transient transgene reactivation, followed by attenuation of its activity. The reactivation induced by 5-aza-Cd was suppressed by concomitant treatment with either 5-mCd or 5-mdCd. These results suggest that the 5-mCs derivatives inhibit and/or reverse 5-aza-Cd-induced reactivation of a silent transgene in tobacco cells.

Efficacy and Safety of Baricitinib in Refractory Chronic Graft-Versus-Host Disease (cGVHD): Preliminary Analysis Results of a Phase 1/2 Study

Background : Chronic Graft-versus-Host Disease (cGVHD) is a multi-organ disorder characterized by immune dysregulation, impaired organ function, and decreased survival. Refractory cGVHD remains an unmet need with limited effective treatment options. Janus kinase (JAK) inhibition targeting JAK-STAT is promising in cGVHD due to this multifaceted pathway's key role in immune cell development, function, and inflammation. Baricitinib is a JAK1/2 inhibitor FDA-approved at 2 mg daily for treatment of rheumatoid arthritis, and which has shown therapeutic promise in preclinical models of GVHD. Herein, we report the preliminary analysis results of a phase 1/2 study exploring the efficacy and safety of the JAK 1/2 inhibitor baricitinib in therapy-refractory cGVHD. Methods : Patients (pts) with therapy-refractory moderate-severe cGVHD per NIH criteria were enrolled on an NCI sponsored treatment protocol (NCT02759731). This is a phase 1/2 single center, single arm study of baricitinib starting at an oral dose of 2 mg daily, given for 28-day cycles, with intra-patient dose escalation to 4 mg daily after 3 months (mos) for a total of 12 cycles. Adverse events (AEs) were monitored and graded per CTCAEv4.3. Clinical responses were measured every 3 mos per the 2014 NIH cGVHD Response Criteria. The primary efficacy endpoint was ORR (CR+PR) at 6 mos; if PR or SD, pts were treated for up to 12 mos and monitored for 12 mos post-completion. Subjects self-report questionnaires included the Lee symptom bother scale (LSS). Peripheral blood samples were collected for pharmacokinetic and correlative studies at several time points throughout study. Results: Twenty pts with refractory cGVHD were enrolled. Median patient age was 54 years (24-68), 55% female, 90% Caucasian. Median time from cGVHD diagnosis to study enrollment was 36.8 mos, with median baseline KPS of 80%. cGVHD NIH global score was severe in all pts (due to sclerotic skin in all except one oral), involving a median of 4 (2-6) organs, and treated with a median of 4 (2-7) lines of prior systemic therapy including ibrutinib in 3. At study enrollment, all but 3 (85%) were on concurrent systemic immunosuppression, including steroids for 12 (60%) at a median dose of 10 mg (2.5-30) prednisone daily. ORR at 6-months was 63% (95% CI 47-87%), with durable responses seen in 7 of 8 evaluable pts at 12-mos. ORR at any time was 90% (85-100%), with median time to ORR of 1.4 mos (1.4-6.3). Organ-specific responses were seen in all involved organs except for lungs (11 organ-specific CRs at 6-mos). Clinically significant improvements in LSS (≥ 6-point reduction) were seen in 7 of 14 (50%) evaluable pts at 6-mos. Median steroid dose-reduction of 4 mg prednisone daily was achieved in 6 (50%) of those on steroids at enrollment. With a median follow up of 24.2 mos, median failure-free survival (FFS) was 20.6 mos (19-NR). 1- and 2-year FFS was 74% (57-97%) and 37% (18-78%), respectively. Of the 8 evaluable pts who completed study, 3 progressed at a median of 7.3 mos (6.9-11.9) after drug discontinuation. No DLT was observed with the 2 mg dose of baricitinib; 16/20 (80%) pts reached dose-escalation to 4 mg at 3 mos. Three pts required dose-reductions: two due to neutropenia, and one due to refractory myalgias. Common AEs, possibly treatment-related, included upper respiratory infection (URI) (13), neutropenia (6), hypophosphatemia (12), and hypertriglyceridemia (5). Asymptomatic, transient reactivation of CMV occurred in 6, EBV in 7, BK viruria in 5 - none of which required treatment. HPV-related eyelid papilloma developed in 2, with no visual changes. One patient with EBV viremia/lymphadenopathy at enrollment was diagnosed with biopsy-proven EBV-PTLD <1 cycle into study. 11 SAEs were reported, of which 5 were possibly drug-related, including hospitalizations for joint infection (n=1), cellulitis (n=2), and URI (n=2). Eleven pts (55%) required dose-interruptions due to AEs, and 9 pts (45%) discontinued treatment at a median 5.6 mos (0.8-10.7) post-initiation due to PD (n=3), EBV-PTLD (n=1), decreased DLCO (n=1), viral URI (n=1), pneumonia (n=1), and other (n=2). There were no deaths on study. Conclusion: The JAK 1/2 inhibitor baricitinib appears well-tolerated and effective for pts with severe cGVHD who progressed through multiple lines of prior therapy. Responses were achieved rapidly and seen across all involved organs, except lungs. Full study results for a total of 31 pts are expected in early 2022. Disclosures No relevant conflicts of interest to declare. OffLabel Disclosure: Baricitinib is currently FDA-approved in the U.S. for treatment of rheumatoid arthritis at a dose of 2 mg by mouth once daily.

Prediction of survival according to kinetic changes of cytokines and hepatitis status following radioembolization with yttrium-90 microspheres

Yttrium-90 radioembolization (Y90-RE) may exert an immunomodulatory effect on the tumor microenvironment of hepatocellular carcinoma (HCC). Whether the host immune alterations after Y90-RE correlated with outcomes and whether Y90-RE affects viral hepatitis reactivation remains unclear. Between July 2014 and July 2015, 18 patients undergoing Y90-RE for HCC were prospectively enrolled. Serum levels of virological markers, cytokines and chemokines were measured at baseline, 2, 4, and 12 weeks after Y90-RE. Factors associated with the clinical outcomes were evaluated. The disease control rate of Y90-RE was 44.4% (8 of 18) at 12 weeks, including 1 case with complete response, 4 cases with partial response, and 3 cases with stable disease. Significant elevation from baseline to week 2 and week 4 were noted in IL-10 level (8.4±33.8, 15.7±31.6, and 16.0±41.7pg/mL, P=0.041 and 0.013, respectively) and IP-10 level (113.5±97.8, 189.1±164.4, and 168.6±150.5pg/mL, P=0.027 and 0.026, respectively). After Y90-RE, transient HBV reactivation occurred in 2 patients, and 1 out of 3 HCV-infected patients exhibited HCV reactivation. Univariate analysis revealed that lower baseline IP-10 (≤200pg/mL) and alanine aminotransferase (ALT) (≤50 U/L) levels were associated with better overall survival. Multivariate analysis identified an IP-10 level of 200pg/mL (HR=4.374, P=0.045) as a predictor of overall survival. Baseline serum IP-10 level is a predictor of survival for HCC patients undergoing Y90-RE. HBV and HCV reactivation may develop after Y90-RE treatment.

Adaptable haemodynamic endothelial cells for organogenesis and tumorigenesis

Endothelial cells adopt tissue-specific characteristics to instruct organ development and regeneration1,2. This adaptability is lost in cultured adult endothelial cells, which do not vascularize tissues in an organotypic manner. Here, we show that transient reactivation of the embryonic-restricted ETS variant transcription factor 2 (ETV2)3 in mature human endothelial cells cultured in a serum-free three-dimensional matrix composed of a mixture of laminin, entactin and type-IV collagen (LEC matrix) ‘resets’ these endothelial cells to adaptable, vasculogenic cells, which form perfusable and plastic vascular plexi. Through chromatin remodelling, ETV2 induces tubulogenic pathways, including the activation of RAP1, which promotes the formation of durable lumens4,5. In three-dimensional matrices—which do not have the constraints of bioprinted scaffolds—the ‘reset’ vascular endothelial cells (R-VECs) self-assemble into stable, multilayered and branching vascular networks within scalable microfluidic chambers, which are capable of transporting human blood. In vivo, R-VECs implanted subcutaneously in mice self-organize into durable pericyte-coated vessels that functionally anastomose to the host circulation and exhibit long-lasting patterning, with no evidence of malformations or angiomas. R-VECs directly interact with cells within three-dimensional co-cultured organoids, removing the need for the restrictive synthetic semipermeable membranes that are required for organ-on-chip systems, therefore providing a physiological platform for vascularization, which we call ‘Organ-On-VascularNet’. R-VECs enable perfusion of glucose-responsive insulin-secreting human pancreatic islets, vascularize decellularized rat intestines and arborize healthy or cancerous human colon organoids. Using single-cell RNA sequencing and epigenetic profiling, we demonstrate that R-VECs establish an adaptive vascular niche that differentially adjusts and conforms to organoids and tumoroids in a tissue-specific manner. Our Organ-On-VascularNet model will permit metabolic, immunological and physiochemical studies and screens to decipher the crosstalk between organotypic endothelial cells and parenchymal cells for identification of determinants of endothelial cell heterogeneity, and could lead to advances in therapeutic organ repair and tumour targeting.

Composite Cu-SSZ-13 and CeO2-SnO2 for enhanced NH3-SCR resistance towards hydrocarbon deactivation

The state-of-the-art Cu-SSZ-13 was mixed with CeO2-SnO2 to form a Composite catalyst which was resistant towards hydrocarbon poisoning of the NH3-mediated NOx-SCR reaction. The Composite was prepared via a solid-state synthesis through ball milling, which did not influence the final morphology. The resistance towards propylene poisoning was remarkably enhanced as the NOx conversion over the Composite catalyst decreased only 9% compared to 40 % over the unmodified Cu-SSZ-13. Transient and dynamic reactivity studies showed that the coke formed during the C3H6 protolytic polymerization was dispersed inside the zeolite pores and the addition of CeO2-SnO2 did not prevent its formation nor enhance its oxidation with O2. The ion-exchanged Cu was the principal active component for the coke and hydrocarbon oxidation and the hydrocarbon poisoning prevention was attributed to the complex interaction between the three primary active sites (Cu – CeO2-SnO2 – protonic sites). Propylene oxidation over Cu-SSZ-13 was inhibited when NO was included in the reaction stream, while over the H-Composite (mixture of H-SSZ-13 and CeO2-SnO2) it had the reverse effect, since C3H6 and NOx oxidation did not compete for the same active sites on CeO2-SnO2. Basing on reactivity studies coupled with IR analysis, a deactivation and poisoning prevention mechanism was proposed, whereby the HONO/nitrate intermediates formed over the CeO2-SnO2 catalyst re-activated the zeolitic copper for the SCR reaction.

Cytomegalovirus infection in AIDS patients. An illustrative case series.

Cytomegalovirus (CMV) is an opportunistic infection (OI) in immunosuppressed patients. However, there are no clear cut-off values available for quantitative plasmatic CMV measures (viral load [VL]) to discriminate those with CMV illness from those infected suffering a transient viral reactivation. To estimate a CMV VL cut-off point that discriminates infected patients and those with CMV related diseases, and to clinically characterize AIDS patients with this OI. Retrospective analysis of AIDS patients admitted by any reason between years 2017 and 2019 and who had a positive plasma CMV VL at any titer. Cases were categorized with illness or infected using accepted criteria and the cut-off value was obtained by receiver operating characteristic curve (ROC) analysis. Twelve patients were identified as having a CMV-associated illness and seven with CMV infection. A CMV VL of 3,800 copies/mL had a sensitivity of 91.6% and 100% specificity to discriminate both states. Of the 12 patients with CMV illness, all were in AIDS stage and only five were receiving HIV therapy. Predominant clinical presentations were gastrointestinal (50%), followed by liver involvement (25%) and CMV disease (25%). All patients were treated with ganciclovir or valganciclovir. Ten patients had a favorable response (83.3%), one patient only had a laboratory improvement (8.3%) and one died during treatment (8.3%). Drug toxicity was recorded in nine patients but in only three cases, a dose adjustment was necessary. The predominant clinical manifestation in our series was gastrointestinal. A CMV VL cutoff level of CMV VL of 3,800 copies / mL is useful to discriminate infected patients from those with CMV related disease.

ATF4-Mediated Upregulation of REDD1 and Sestrin2 Suppresses mTORC1 Activity during Prolonged Leucine Deprivation

Background:The protein kinase target of rapamycin (mTOR) in complex 1 (mTORC1) is activated by amino acids and in turn upregulates anabolic processes. Under nutrient-deficient conditions, e.g., amino acid insufficiency, mTORC1 activity is suppressed and autophagy is activated. Intralysosomal amino acids generated by autophagy reactivate mTORC1. However, sustained mTORC1 activation during periods of nutrient insufficiency would likely be detrimental to cellular homeostasis. Thus, mechanisms must exist to prevent amino acids released by autophagy from reactivating the kinase. Objective:The objective of the present study was to test whether mTORC1 activity is inhibited during prolonged leucine deprivation through ATF4-dependent upregulation of the mTORC1 suppressors regulated in development and DNA damage response 1 (REDD1) and Sestrin2. Methods:Mice (8 wk old; C57Bl/6 × 129SvEV) were food deprived (FD) overnight and one-half were refed the next morning. Mouse embryo fibroblasts (MEFs) deficient in ATF4, REDD1, and/or Sestrin2 were deprived of leucine for 0–16 h. mTORC1 activity and ATF4, REDD1, and Sestrin2 expression were assessed in liver and cell lysates. Results:Refeeding FD mice resulted in activation of mTORC1 in association with suppressed expression of both REDD1 and Sestrin2 in the liver. In cells in culture, mTORC1 exhibited a triphasic response to leucine deprivation, with an initial suppression followed by a transient reactivation from 2 to 4 h and a subsequent resuppression after 8 h. Resuppression occurred concomitantly with upregulated expression of ATF4, REDD1, and Sestrin2. However, in cells lacking ATF4, neither REDD1 nor Sestrin2 expression was upregulated by leucine deprivation, and resuppression of mTORC1 was absent. Moreover, in cells lacking either REDD1 or Sestrin2, mTORC1 resuppression was attenuated, and in cells lacking both proteins resuppression was further blunted. Conclusions:The results suggest that leucine deprivation upregulates expression of both REDD1 and Sestrin2 in an ATF4-dependent manner, and that upregulated expression of both proteins is involved in resuppression of mTORC1 during prolonged leucine deprivation.

The reactivity and initial carbonization of an Unsupported Nickel catalyst in dry reforming of methane

High speed product gas analysis during the dry reforming of CH4 allows the observation of transient elevated H2 and CO production rates, combined with high initial conversions of CH4 and CO2. The transients are observed in the first 120 s of the reaction, followed by a lower steady-state production rate after 3–5 min. The catalytic reactivity in the initial 120 s is important in understanding the catalyst performance and determining the reactions responsible for carbon deposition. Monitoring the changes in the H2 and CH4 partial pressures from the start, through the transient production regime, and on through the steady-state regime, shows that the transient reactivity is directly related to the decomposition of CH4. This finding is further supported by the linear trend found between the H2/CO ratio and the carbon deposition in the peak region of the product gas profile. Although significant amounts of carbon are deposited on the Ni surface, it is not completely deactivated at any of the reaction temperatures in the 500–800 °C range explored herein. Characterizing the initial reactivity in terms of carbon deposition and catalyst performance in dry reforming of CH4 may lead to changes in the sampling technique for researchers working with reforming reactions, and optimized catalysts that exhibit reduced initial carbon deposition.

Prevention of Orbitopathy by Oral or Intravenous Steroid Prophylaxis in Short Duration Graves' Disease Patients Undergoing Radioiodine Ablation: A Prospective Randomized Control Trial Study.

Background: Radioiodine (RAI) is a known risk factor for activation or de novo occurrence of Graves' orbitopathy (GO). Several studies demonstrated that GO can be prevented by glucocorticoids (GCs) in patients with pre-existing GO. We have previously shown that Graves' disease duration (GDd) <5 years is a risk factor for RAI-induced GO. We studied the effect of prophylaxis with either oral GCs (OGCs) or intravenous GCs (IVGCs) on GO activation in patients with GDd. Methods: In total, 99 hyperthyroid patients without GO or with pre-existing inactive GO with GDd <5 years were randomized to receive IVGCs (N = 49) or OGCs (N = 50) before RAI; 22 patients with GDd >5 did not receive steroids and were studied as controls. All patients underwent ophthalmological assessment before and 45, 90, 180 days and for a 5-year follow-up after RAI. Serum thyrotropin (TSH) receptor antibodies (TRAbs), thyroid hormones, and thyroid volume (TV) were also measured in response to RAI therapy and steroid prophylaxis. Results: No patient on prophylaxis developed GO after RAI. One woman of the control group, without steroid prophylaxis, and who had a marked elevation of her TSH, showed transient reactivation of GO, which spontaneously improved after restoring euthyroidism. On follow-up at 12 and 20 months after RAI, two patients developed overt optic neuropathy. A smaller TV was associated with a higher prevalence of RAI-induced hypothyroidism. Serum TRAbs increased significantly after RAI (p < 0.0001) but less in patients receiving steroids than in those without prophylaxis at 45 days (p < 0.01). Conclusions: The risk of RAI-induced GO can be prevented in all patients with GDd <5 years by steroids. Such treatment may not be necessary in patients with GDd >5 years. The blunting of TRAb elevation after RAI may be related to the prophylactic effect of steroids.

Isolated cortical computations during delta waves support memory consolidation.

Delta waves have been described as periods of generalized silence across the cortex, and their alternation with periods of endogenous activity results in the slow oscillation of slow-wave sleep. Despite evidence that delta waves are instrumental for memory consolidation, their specific role in reshaping cortical functional circuits remains puzzling. In a rat model, we found that delta waves are not periods of complete silence and that the residual activity is not mere neuronal noise. Instead, cortical cells involved in learning a spatial memory task subsequently formed cell assemblies during delta waves in response to transient reactivation of hippocampal ensembles during ripples. This process occurred selectively during endogenous or induced memory consolidation. Thus, delta waves represent isolated cortical computations tightly related to ongoing information processing underlying memory consolidation.

CD34+ Selected Hematopoietic Transplant, an Option When Compliance Is a Concern in Pediatric Patients

Background The incidence of non-compliance is as high as 60% in pediatrics, making it a serious concern after hematopoietic stem cell transplant (HSCT), increasing treatment related mortality (TRM), graft versus host disease (GVHD) and decreases overall survival (OS). Risk of GVHD is 30-60%, therefore mitigating this risk when compliance is a concern is crucial. CD34+ selected grafts, have a very low incidence GVHD and can abolish the need for post HSCT immune suppression. Historically T-depleted grafts have been used to reduce incidence of GVHD for patients at risk (e.g. mismatched donor and fanconi anemia (FA) however it has not been studied in the context of compliance. Objectives Assess our institutional experience with pediatric T-depleted HSCT in the setting of risk of non-compliance. We hypothesized that T-depleted grafts result in adequate engraftment without increasing incidence of infections, graft failure and eliminate the risk for GVHD. Methods Retrospective chart review. Patients with FA or a highly mismatched donor were excluded. Results Five pediatric patients' underwent a CD34+ selected HSCT at our institution between 2016 and 2018, using reduced intensity conditioning (alemuzumab, fludarabine, melphalan). Stem cells were collected using the Miltenyi Biotec CliniMACS system. The median age and cell dose at HSCT were 3.4 years and 21.5 × 106 TNC/kg respectively. Demographics are summarized in table 1. All 5 patients had aplastic anemia and severe bone marrow failure. Median day of neutrophil and platelet recovery was day +11 and +12 respectively. No post HSCT calcineurin inhibitors were used and there was no GVHD. Morbidity post HSCT was most commonly transient viral reactivation and stool infections. The OS was 100% with sustained engraftment above 95% in 4, and the median follow up of 747 days. One patient had primary graft failure after 3 stem cell infusions and auto recovered at day +46 after last stem cell infusion and demonstrated adequate immune reconstitution after conditioning and HSCT. Conclusion These data support our hypothesis that T-depleted grafts can be an option for patients' with marrow failure syndromes and who are at risk for non-compliance with acceptable morbidity.

Transient Reactivation of a Deep‐Seated Landslide by Undrained Loading Captured With Repeat Airborne and Terrestrial Lidar

AbstractLandslides reactivate due to external environmental forcing or internal mass redistribution, but the process is rarely documented quantitatively. We capture the three‐dimensional, 1‐m resolution surface deformation field of a transiently reactivated landslide with image correlation of repeat airborne lidar. Undrained loading by two debris flows in the landslide's head, rather than external forcing, triggered reactivation. After that loading, the lower 2 km of the landslide advanced by up to 14 m in 2 years before completely stopping. The displacement field over those 2 years implies that the slip surface gained 1 kPa of shear strength, which was likely accomplished by a negative dilatancy‐pore pressure feedback as material deformed around basal roughness elements. Thus, landslide motion can be decoupled from external environmental forcing in cases, motivating the need to better understand internal perturbations to the stress field to predict hazards and sediment fluxes as landscapes evolve.

Validation of PSI best estimate plus uncertainty methodology against SPERT-III reactivity initiated accident experiments

This research aims at validating the SIMULATE-3K code and complementing the results with the quantification of nuclear data uncertainties against the Special Power Excursion Reactor Test III (SPERT-III) experiments. To that aim, the SHARK-X methodology, under development at PSI, for the propagation of nuclear data uncertainties in CASMO5 2-D lattice calculations to 3-D core transient simulations is applied for the analysis of a SPERT-III super-prompt critical test conducted at cold startup conditions. Concerning transient results, both total power and reactivity show a good agreement with the measurements at the initial phase of power excursion, while a slight discrepancy is obtained at the final phase of the transient. The estimated uncertainties regarding both steady-state parameters such as k-eff and static reactivity worth, as well as dynamical quantities such as power pulse width and enthalpies are presented. Results show non-negligible sensitivity upon the employed nuclear data library. The uncertainty quantification results show relatively small biases for k-eff and reactivity. The uncertainty in peak power is around 3%, while it is negligible for the time to peak power and the pulse width. The time evolution of the standard deviation and skewness of the total power showed special shapes with relatively high maximum values. In addition, the uncertainty due to nuclear data in the two important safety parameters, i.e. maximum nodal fuel temperature and enthalpy reaches maximum value around 2% and 10%, respectively.

Beyond Flatland: Exploring 3D Cu Catalysts for CO2 Reduction

The electrochemical CO2 reduction reaction (CO2RR) has become a promising path forward to a carbon neutral energy cycle by combining carbon capture with hydrocarbon production, especially if excess power from regenerative resources such as wind and solar is available and used. The key obstacle for deployment of the one-step electrochemical CO2RR technology is the development of low-cost electrocatalysts that facilitate energy-efficient production of hydrocarbons from CO2 with high selectivity and long-term stability. Here, copper has emerged as the most promising catalyst for the formation of hydrocarbons at ambient pressures and temperatures. We have developed a unique expertise in the synthesis of nanoporous metal catalysts including nanoporous Cu (npCu) made from CuMn and CuZn alloys, Cu nanocube surface functionalizations and Cu-oxide/Cu nanowire forests (Fig. 1). Preliminary CO2RR tests of these materials have confirmed that oxidized npCu electrodes have a significantly increased transient reactivity towards the electrochemical reduction of CO2. We will discuss results using a novel electrochemical cell geometry that is designed to take full advantage of the high surface area of the catalyst. Fig. 1: (a) NpCu prepared by dealloying CuZn alloys; (b) Cu nanocube surface functionalization of npCu; (c) Cu-oxide nanowires grown on Cu foam formed by annealing in air (1h @ 500C). This work was performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under Contract DE-AC52-07NA27344 Figure 1

Unique molecular events during reprogramming of human somatic cells to induced pluripotent stem cells (iPSCs) at naïve state.

Derivation of human naïve cells in the ground state of pluripotency provides promising avenues for developmental biology studies and therapeutic manipulations. However, the molecular mechanisms involved in the establishment and maintenance of human naïve pluripotency remain poorly understood. Using the human inducible reprogramming system together with the 5iLAF naïve induction strategy, integrative analysis of transcriptional and epigenetic dynamics across the transition from human fibroblasts to naïve iPSCs revealed ordered waves of gene network activation sharing signatures with those found during embryonic development from late embryogenesis to pre-implantation stages. More importantly, Transcriptional analysis showed a significant transient reactivation of transcripts with 8-cell-stage-like characteristics in the late stage of reprogramming, suggesting transient activation of gene network with human zygotic genome activation (ZGA)-like signatures during the establishment of naïve pluripotency. Together, Dissecting the naïve reprogramming dynamics by integrative analysis improves the understanding of the molecular features involved in the generation of naïve pluripotency directly from somatic cells.

Neuronal baseline shifts underlying boundary setting during free recall

Asked to freely recall items from a predefined set (e.g., animals), we rarely recall a wrong exemplar (e.g., a vegetable). This capability is so powerful and effortless that it is essentially taken for granted, yet, surprisingly, the underlying neuronal mechanisms are unknown. Here we investigate this boundary setting mechanism using intracranial recordings (ECoG), in 12 patients undergoing epilepsy monitoring engaged in episodic free recall. After viewing vivid photographs from two categories (famous faces and places), patients were asked to freely recall these items, targeting each category in separate blocks. Our results reveal a rapid and sustained rise in neuronal activity (“baseline shift”) in high-order visual areas that persists throughout the free recall period and reflects the targeted category. We further show a more transient reactivation linked to individual recall events. The results point to baseline shift as a flexible top−down mechanism that biases spontaneous recall to remain within the required categorical boundaries.

Dynamics of B Cell Recovery In Kidney/Bone Marrow Transplant Recipients

Previous studies identified B cell gene signatures and predominance of specific B cell subsets as a marker of operational tolerance after kidney transplantation. These findings suggested a role for B cells in the establishment or maintenance of tolerance. Here we analyzed B cell recovery in 4 subjects, 3 of whom achieved tolerance after combined kidney/bone marrow transplantation. Peripheral B cell subsets were examined longitudinally by flow cytometry. Immunoglobulin heavy chain repertoire analysis was performed using next-generation sequencing. Lastly, the patients' serum reactivity to HLA was assessed by Luminex. B cell counts recovered approximately 1 year posttransplant except for 1 subject who experienced delayed reconstitution. This subject resumed immunosuppression for acute rejection at 10 months posttransplant and underwent preemptive retransplantation at 3 years for chronic rejection. B cell recovery was accompanied by a high frequency of CD20 + CD24CD38 transitional B cells and a diversified clonal repertoire. However, all 4 subjects showed prevalence of CD20 + CD27+ memory B cells around 6 months posttransplant when B cell counts were still low and the clonal B cell repertoire very limited. The predominance of memory B cells was also associated with high levels of somatically mutated immunoglobulin heavy chain variable sequences and transient serum reactivity to HLA. Our observations reveal the presence of memory B cells early posttransplant that likely escaped the preparative regimen at a time consistent with the establishment of tolerance. Further studies are warranted to characterize the functional properties of these persisting memory cells and evaluate their potential contribution to tolerance induction.

Network-wide reorganization of procedural memory during NREM sleep revealed by fMRI.

Sleep is necessary for the optimal consolidation of newly acquired procedural memories. However, the mechanisms by which motor memory traces develop during sleep remain controversial in humans, as this process has been mainly investigated indirectly by comparing pre- and post-sleep conditions. Here, we used functional magnetic resonance imaging and electroencephalography during sleep following motor sequence learning to investigate how newly-formed memory traces evolve dynamically over time. We provide direct evidence for transient reactivation followed by downscaling of functional connectivity in a cortically-dominant pattern formed during learning, as well as gradual reorganization of this representation toward a subcortically-dominant consolidated trace during non-rapid eye movement (NREM) sleep. Importantly, the putamen functional connectivity within the consolidated network during NREM sleep was related to overnight behavioral gains. Our results demonstrate that NREM sleep is necessary for two complementary processes: the restoration and reorganization of newly-learned information during sleep, which underlie human motor memory consolidation.

In This Issue

HomeCirculation ResearchVol. 121, No. 5In This Issue Free AccessIn BriefPDF/EPUBAboutView PDFView EPUBSections ToolsAdd to favoritesDownload citationsTrack citationsPermissions ShareShare onFacebookTwitterLinked InMendeleyReddit Jump toFree AccessIn BriefPDF/EPUBIn This Issue Ruth Williams Ruth WilliamsRuth Williams Search for more papers by this author Originally published18 Aug 2017https://doi.org/10.1161/RES.0000000000000173Circulation Research. 2017;121:469Role of Hey2 in Transmural Electrical Patterning (p 537)Download figureDownload PowerPointVeerman et al determine the likely effect of a Brugada syndrome risk allele.Brugada syndrome is characterized by abnormal electrical signals in the heart and a heightened risk of sudden death. A genome-wide association study (GWAS) has identified a Brugada-linked single nucleotide polymorphism (SNP) at the genetic locus 6q22.31. This SNP lies close to the gene for transcription factor HEY2; however, whether HEY2 contributes to Brugada syndrome is unclear. Veerman and colleagues examined gene expression data from 190 human left ventricle samples and found that, of 8 genes in the 6q22.31 region, only HEY2 showed significant association—increased expression—with the Brugada risk allele. Further, genome-wide coexpression analyses showed that, of 15 617 genes examined, the expression of KCNIP2, which encodes an ion channel subunit, was most tightly correlated with the expression of HEY2. The team went on to show that myocardial expression of KCNIP2 was lower in HEY2-deficient mice than in wild-type animals, suggesting that HEY2 regulates KCNIP2. Indeed, these HEY2-deficient animals exhibited abnormal electrical patterning in the ventricle wall consistent with altered ion channel function. The results indicate that high HEY2 expression increases the risk of Brugada syndrome and highlight the utility of expression analyses for uncovering potential functions of GWAS identified loci.Notch and Sick Sinus Syndrome (p 549)Download figureDownload PowerPointTransient Notch activation causes long-term electrophysiological problems in the heart, say Qiao et al.Cell–cell signaling via transmembranous Notch proteins is essential for a variety of developmental processes, including the formation and function of several cardiovascular structures and systems. In adult mouse heart cells, Notch signaling is generally quiescent, but after an injury—such as a myocardial infarction—Notch is transiently reactivated, which in turn leads to altered ion channel expression and aberrant electrical properties. Qiao and colleagues have now examined the effects of such transient Notch reactivation in more detail. They found that in mice subjected to transient atrial Notch activation, there was significant heart rate slowing, sinus pausing, and dysregulation of sinus node and atrial conduction factors. Furthermore, these transcriptional and electrophysiological changes were sustained long after Notch signaling had returned to normal. Heart rate, for example, remained low for a year. Because cardiac injuries can predispose patients to atrial arrhythmias, the researchers suggest that a thorough understanding of the long-term cardiac effects of transient, injury-induced Notch activation may reveal pathways and factors that could be targeted for antiarrhythmic interventions.Inhibition of Meg3 Prevents Cardiac Remodeling (p 575)Download figureDownload PowerPointPiccoli and colleagues target a noncoding RNA to prevent cardiac remodeling.Fibroblasts contribute to myocardial remodeling during pressure overload-induced cardiac hypertrophy. These cells secrete factors that reorganize the extracellular matrix (ECM), creating fibrosis and heart dysfunction. To learn more about the remodeling actions of cardiac fibroblasts, Piccoli and colleagues investigated the array of long noncoding RNAs (lncRNAs) produced by these cells. LncRNAs regulate a variety of cellular processes and certain lncRNAs have been implicated in cardiovascular disease. However, the roles of cardiac fibroblast lncRNAs have not been thoroughly studied. In mice with pressure-induced hypertrophy, the team identified 3 lncRNAs that were specifically dysregulated in cardiac fibroblasts. Of these, one called Meg3 was the most abundant and has previously been implicated in fibrosis. Functional studies of Meg3 revealed that the RNA, by binding and activating transcription factor p53, promotes the expression of an ECM enzyme called MMP-2. The team also showed that antisense inhibition of Meg3 could prevent the pressure-induced increase in MMP-2 as well as the associated fibrosis and hypertrophy in mice. Inhibition of Meg3 may, therefore, be an effective way to prevent cardiac fibrosis and dysfunction during heart disease, say the authors. Previous Back to top Next FiguresReferencesRelatedDetails August 18, 2017Vol 121, Issue 5 Advertisement Article InformationMetrics © 2017 American Heart Association, Inc.https://doi.org/10.1161/RES.0000000000000173 Originally publishedAugust 18, 2017 PDF download Advertisement