The process of carbon capture and sequestration has been proposed as a method of mitigating the build-up of greenhouse gases in the atmosphere. If implemented, the cost of electricity generated by a ...fossil fuel-burning power plant would rise substantially, owing to the expense of removing CO2 from the effluent stream. There is therefore an urgent need for more efficient gas separation technologies, such as those potentially offered by advanced solid adsorbents. Here we show that diamine-appended metal-organic frameworks can behave as 'phase-change' adsorbents, with unusual step-shaped CO2 adsorption isotherms that shift markedly with temperature. Results from spectroscopic, diffraction and computational studies show that the origin of the sharp adsorption step is an unprecedented cooperative process in which, above a metal-dependent threshold pressure, CO2 molecules insert into metal-amine bonds, inducing a reorganization of the amines into well-ordered chains of ammonium carbamate. As a consequence, large CO2 separation capacities can be achieved with small temperature swings, and regeneration energies appreciably lower than achievable with state-of-the-art aqueous amine solutions become feasible. The results provide a mechanistic framework for designing highly efficient adsorbents for removing CO2 from various gas mixtures, and yield insights into the conservation of Mg(2+) within the ribulose-1,5-bisphosphate carboxylase/oxygenase family of enzymes.
Celotno besedilo
Dostopno za:
DOBA, IJS, IZUM, KILJ, KISLJ, NUK, PILJ, PNG, SAZU, SBMB, SIK, UILJ, UKNU, UL, UM, UPUK
Commensal gut microflora and dietary fiber protect against colonic inflammation and colon cancer through unknown targets. Butyrate, a bacterial product from fermentation of dietary fiber in the ...colon, has been implicated in this process. GPR109A (encoded by Niacr1) is a receptor for butyrate in the colon. GPR109A is also a receptor for niacin, which is also produced by gut microbiota and suppresses intestinal inflammation. Here we showed that Gpr109a signaling promoted anti-inflammatory properties in colonic macrophages and dendritic cells and enabled them to induce differentiation of Treg cells and IL-10-producing T cells. Moreover, Gpr109a was essential for butyrate-mediated induction of IL-18 in colonic epithelium. Consequently, Niacr1−/− mice were susceptible to development of colonic inflammation and colon cancer. Niacin, a pharmacological Gpr109a agonist, suppressed colitis and colon cancer in a Gpr109a-dependent manner. Thus, Gpr10a has an essential role in mediating the beneficial effects of gut microbiota and dietary fiber in colon.
Display omitted
•Commensal metabolite butyrate and niacin induce IL-18 in colon via Gpr109a•Butyrate and niacin induce IL-10 and Aldh1a in APCs in a Gpr109a-dependent manner•Niacr1−/− mice exhibit increased risk for colitis and colon cancer•Gpr109a signaling protects colon health during deficiency of gut bacteria and dietary fiber
The widespread deployment of carbon capture and sequestration as a climate change mitigation strategy could be facilitated by the development of more energy-efficient adsorbents. Diamine-appended ...metal–organic frameworks of the type diamine–M2(dobpdc) (M = Mg, Mn, Fe, Co, Ni, Zn; dobpdc4– = 4,4′-dioxidobiphenyl-3,3′-dicarboxylate) have shown promise for carbon-capture applications, although questions remain regarding the molecular mechanisms of CO2 uptake in these materials. Here we leverage the crystallinity and tunability of this class of frameworks to perform a comprehensive study of CO2 chemisorption. Using multinuclear nuclear magnetic resonance (NMR) spectroscopy experiments and van-der-Waals-corrected density functional theory (DFT) calculations for 13 diamine–M2(dobpdc) variants, we demonstrate that the canonical CO2 chemisorption products, ammonium carbamate chains and carbamic acid pairs, can be readily distinguished and that ammonium carbamate chain formation dominates for diamine–Mg2(dobpdc) materials. In addition, we elucidate a new chemisorption mechanism in the material dmpn–Mg2(dobpdc) (dmpn = 2,2-dimethyl-1,3-diaminopropane), which involves the formation of a 1:1 mixture of ammonium carbamate and carbamic acid and accounts for the unusual adsorption properties of this material. Finally, we show that the presence of water plays an important role in directing the mechanisms for CO2 uptake in diamine–M2(dobpdc) materials. Overall, our combined NMR and DFT approach enables a thorough depiction and understanding of CO2 adsorption within diamine–M2(dobpdc) compounds, which may aid similar studies in other amine-functionalized adsorbents in the future.
Steaming out captured CO
2
Although natural gas is less carbon dioxide (CO
2
)–intensive than coal, capturing its emitted CO
2
can be more challenging because combined-cycle natural gas combustion ...has a CO
2
concentration that is only one-third of that of coal combustion and contains high concentrations of oxygen and water. Kim
et al.
report on a tetraamine-functionalized magnesium metal–organic framework that displays two-step cooperative CO
2
adsorption that leads to a high CO
2
capacity and adsorption enthalpy (see the Perspective by Peh and Zhao). This material could capture CO
2
from humid air and could be regenerated with steam, a method that is more economical than temperature or pressure swing methods.
Science
, this issue p.
392
; see also p.
372
Tetraamine-functionalized metal–organic frameworks enable CO
2
capture from humid streams, as well as steam regeneration.
Natural gas has become the dominant source of electricity in the United States, and technologies capable of efficiently removing carbon dioxide (CO
2
) from the flue emissions of natural gas–fired power plants could reduce their carbon intensity. However, given the low partial pressure of CO
2
in the flue stream, separation of CO
2
is particularly challenging. Taking inspiration from the crystal structures of diamine-appended metal–organic frameworks exhibiting two-step cooperative CO
2
adsorption, we report a family of robust tetraamine-functionalized frameworks that retain cooperativity, leading to the potential for exceptional efficiency in capturing CO
2
under the extreme conditions relevant to natural gas flue emissions. The ordered, multimetal coordination of the tetraamines imparts the materials with extraordinary stability to adsorption-desorption cycling with simulated humid flue gas and enables regeneration using low-temperature steam in lieu of costly pressure or temperature swings.
Supported by increasingly available reserves, natural gas is achieving greater adoption as a cleaner-burning alternative to coal in the power sector. As a result, carbon capture and sequestration ...from natural gas-fired power plants is an attractive strategy to mitigate global anthropogenic CO2 emissions. However, the separation of CO2 from other components in the flue streams of gas-fired power plants is particularly challenging due to the low CO2 partial pressure (∼40 mbar), which necessitates that candidate separation materials bind CO2 strongly at low partial pressures (≤4 mbar) to capture ≥90% of the emitted CO2. High partial pressures of O2 (120 mbar) and water (80 mbar) in these flue streams have also presented significant barriers to the deployment of new technologies for CO2 capture from gas-fired power plants. Here, we demonstrate that functionalization of the metal–organic framework Mg2(dobpdc) (dobpdc4– = 4,4′-dioxidobiphenyl-3,3′-dicarboxylate) with the cyclic diamine 2-(aminomethyl)piperidine (2-ampd) produces an adsorbent that is capable of ≥90% CO2 capture from a humid natural gas flue emission stream, as confirmed by breakthrough measurements. This material captures CO2 by a cooperative mechanism that enables access to a large CO2 cycling capacity with a small temperature swing (2.4 mmol CO2/g with ΔT = 100 °C). Significantly, multicomponent adsorption experiments, infrared spectroscopy, magic angle spinning solid-state NMR spectroscopy, and van der Waals-corrected density functional theory studies suggest that water enhances CO2 capture in 2-ampd–Mg2(dobpdc) through hydrogen-bonding interactions with the carbamate groups of the ammonium carbamate chains formed upon CO2 adsorption, thereby increasing the thermodynamic driving force for CO2 binding. In light of the exceptional thermal and oxidative stability of 2-ampd–Mg2(dobpdc), its high CO2 adsorption capacity, and its high CO2 capture rate from a simulated natural gas flue emission stream, this material is one of the most promising adsorbents to date for this important separation.
The approval of anti-programmed death ligand 1 (PD-L1) and anti-programmed death 1 agents has expanded treatment options for patients with locally advanced or metastatic urothelial carcinoma. ...Avelumab, a human monoclonal anti-PD-L1 antibody, has shown promising antitumour activity and safety in this disease. We aimed to assess the safety profile in patients (both post-platinum therapy and cisplatin-naive) treated with avelumab and to assess antitumour activity of this drug in post-platinum patients.
In this pooled analysis of two cohorts from the phase 1 dose-expansion JAVELIN Solid Tumor study, patients aged 18 years and older with histologically or cytologically confirmed locally advanced or metastatic urothelial carcinoma that had progressed after at least one previous platinum-based chemotherapy were enrolled from 80 cancer treatment centres or hospitals in the USA, Europe, and Asia. Eligible patients had adequate end-organ function, an Eastern Cooperative Oncology Group performance status of 0 or 1, life expectancy of at least 3 months, and at least one measurable lesion. Cisplatin-ineligible patients who might have been previously treated in the perioperative setting, including platinum-naive patients, were also eligible. Patients unselected for PD-L1 expression received avelumab (10 mg/kg, 1 h intravenous infusion) every 2 weeks until confirmed disease progression, unacceptable toxicity, or other criterion for withdrawal. The primary endpoint for this efficacy expansion cohort was confirmed best overall response (according to RECIST version 1.1), adjudicated by independent review. Safety analysis was done in all patients who received at least one dose of avelumab. Antitumour activity was assessed in post-platinum patients who received at least one dose of avelumab. This trial is registered with ClinicalTrials.gov, number NCT01772004; enrolment in this cohort of patients with metastatic urothelial carcinoma is closed and the trial is ongoing.
Between Sept 3, 2014, and March 15, 2016, 329 patients with advanced metastatic urothelial carcinoma were screened for enrolment into this study; 249 patients were eligible and received treatment with avelumab for a median of 12 weeks (IQR 6·0–19·7) and followed up for a median of 9·9 months (4·3–12·1). Safety and antitumour activity were evaluated at data cutoff on June 9, 2016. In 161 post-platinum patients with at least 6 months of follow-up, a best overall response of complete or partial response was recorded in 27 patients (17%; 95% CI 11–24), including nine (6%) complete responses and 18 (11%) partial responses. The most frequent treatment-related adverse events (any grade in ≥10% patients) were infusion-related reaction (73 29%; all grade 1–2) and fatigue (40 16%). Grade 3 or worse treatment-related adverse events occurred in 21 (8%) of 249 patients, the most common of which were fatigue (four 2%), and asthenia, elevated lipase, hypophosphataemia, and pneumonitis in two (1%) patients each. 19 (8%) of 249 patients had a serious adverse event related to treatment with avelumab, and one treatment-related death occurred (pneumonitis).
Avelumab showed antitumour activity in the treatment of patients with platinum-refractory metastatic urothelial carcinoma; a manageable safety profile was reported in all avelumab-treated patients. These data provide the rationale for therapeutic use of avelumab in metastatic urothelial carcinoma and it has received accelerated US FDA approval in this setting on this basis.
Merck KGaA, and Pfizer Inc.
Final data are presented for the ORAL Sequel long-term extension (LTE) study evaluating the safety and efficacy of tofacitinib 5 mg and 10 mg twice daily (BID) for up to 9.5 years in patients with ...rheumatoid arthritis (RA).
Eligible patients had previously completed a phase 1, 2, or 3 qualifying index study of tofacitinib and received open-label tofacitinib 5 mg or 10 mg BID. Stable background therapy, including csDMARDs, was continued; adjustments to tofacitinib or background therapy were permitted at investigators' discretion. Assignment to dose groups (5 mg or 10 mg BID) was based on patients' average total daily dose. The primary objective was to determine the long-term safety and tolerability of tofacitinib 5 mg and 10 mg BID; the key secondary objective was to evaluate the long-term persistence of efficacy.
Between February 5, 2007, and November 30, 2016, 4481 patients were enrolled. Total tofacitinib exposure was 16,291 patient-years. Safety data are reported up to month 114 for all tofacitinib; efficacy data are reported up to month 96 for tofacitinib 5 mg BID and month 72 for 10 mg BID (with low patient numbers limiting interpretation beyond these time points). Overall, 52% of patients discontinued (24% due to adverse events AEs and 4% due to insufficient clinical response); the safety profile remained consistent with that observed in prior phase 1, 2, 3, or LTE studies. The incidence rate (IR; number of patients with events per 100 patient-years) for AEs leading to discontinuation was 6.8. For all-cause AEs of special interest, IRs were 3.4 for herpes zoster, 2.4 for serious infections, 0.8 for malignancies excluding non-melanoma skin cancer, 0.4 for major adverse cardiovascular events, and 0.3 for all-cause mortality. Clinically meaningful improvements in the signs and symptoms of RA and physical functioning, which were observed in the index studies, were maintained.
Tofacitinib 5 mg and 10 mg BID demonstrated a consistent safety profile (as monotherapy or combination therapy) and sustained efficacy in this open-label LTE study of patients with RA. Safety data are reported up to 9.5 years, and efficacy data up to 8 years, based on adequate patient numbers to support conclusions.
NCT00413699 , funded by Pfizer Inc (date of trial registration: December 20, 2006).
Display omitted
► Amyloid-beta (1–40) is partially folded at 15°C, pH 7.3 in 50mM NaCl. ► Amyloid-beta (1–40) forms a 310 helix from H13 to D23. ► N- and C-termini are unstructured but collapse ...against the helix. ► Low temperature and moderate salt conformations may favor helical conformations of amyloid-beta (1–40).
Aggregation of the Aβ1–40 peptide is linked to the development of extracellular plaques characteristic of Alzheimer’s disease. While previous studies commonly show the Aβ1–40 is largely unstructured in solution, we show that Aβ1–40 can adopt a compact, partially folded structure. In this structure (PDB ID: 2LFM), the central hydrophobic region of the peptide forms a 310 helix from H13 to D23 and the N- and C-termini collapse against the helix due to the clustering of hydrophobic residues. Helical intermediates have been predicted to be crucial on-pathway intermediates in amyloid fibrillogenesis, and the structure presented here presents a new target for investigation of early events in Aβ1–40 fibrillogenesis.
Allosteric drug development holds promise for delivering medicines that are more selective and less toxic than those that target orthosteric sites. To date, the discovery of allosteric binding sites ...and lead compounds has been mostly serendipitous, achieved through high-throughput screening. Over the past decade, structural data has become more readily available for larger protein systems and more membrane protein classes (e.g., GPCRs and ion channels), which are common allosteric drug targets. In parallel, improved simulation methods now provide better atomistic understanding of the protein dynamics and cooperative motions that are critical to allosteric mechanisms. As a result of these advances, the field of predictive allosteric drug development is now on the cusp of a new era of rational structure-based computational methods. Here, we review algorithms that predict allosteric sites based on sequence data and molecular dynamics simulations, describe tools that assess the druggability of these pockets, and discuss how Markov state models and topology analyses provide insight into the relationship between protein dynamics and allosteric drug binding. In each section, we first provide an overview of the various method classes before describing relevant algorithms and software packages.
SMARCB1 (also known as SNF5, INI1, and BAF47), a core subunit of the SWI/SNF (BAF) chromatin-remodeling complex, is inactivated in nearly all pediatric rhabdoid tumors. These aggressive cancers are ...among the most genomically stable, suggesting an epigenetic mechanism by which SMARCB1 loss drives transformation. Here we show that, despite having indistinguishable mutational landscapes, human rhabdoid tumors exhibit distinct enhancer H3K27ac signatures, which identify remnants of differentiation programs. We show that SMARCB1 is required for the integrity of SWI/SNF complexes and that its loss alters enhancer targeting-markedly impairing SWI/SNF binding to typical enhancers, particularly those required for differentiation, while maintaining SWI/SNF binding at super-enhancers. We show that these retained super-enhancers are essential for rhabdoid tumor survival, including some that are shared by all subtypes, such as SPRY1, and other lineage-specific super-enhancers, such as SOX2 in brain-derived rhabdoid tumors. Taken together, our findings identify a new chromatin-based epigenetic mechanism underlying the tumor-suppressive activity of SMARCB1.
PDF
