Abstract Background The oral vasopressin-2 receptor antagonist tolvaptan causes aquaresis in patients with volume overload, potentially facilitating decongestion and improving the clinical course of ...patients with acute heart failure (AHF). Objectives To address the acute use of tolvaptan to improve congestion in AHF, we conducted the Targeting Acute Congestion with Tolvaptan in Congestive Heart Failure (TACTICS-HF, NCT01644331) study. Methods TACTICS-HF randomized patients within 24 hours of AHF presentation in a prospective, double blind, placebo-controlled trial. Patients were eligible regardless of ejection fraction, and were randomized to either 30 mg of tolvaptan or placebo given at 0, 24, and 48 hours, with a fixed-dose furosemide regimen as background therapy. The primary endpoint was the proportion of patients considered responders at 24 hours. Secondary endpoints included symptom improvement, changes in renal function, and clinical events. Results A total of 257 patients were randomized. Dyspnea relief by Likert scale was similar between tolvaptan and placebo at 8 hours (25% moderately or markedly improved for tolvaptan vs. 28% placebo, p=0.59) and at 24 hours (50% tolvaptan vs. 47% placebo, p=0.80). Need for rescue therapy was also similar at 24 hours (21% tolvaptan, 18% placebo, p=0.57). The proportion defined as responders at 24 hours (primary study endpoint) was 16% for tolvaptan and 20% for placebo (p=0.32). Tolvaptan resulted in greater weight loss and net fluid loss compared to placebo, but tolvaptan-treated patients were more likely to experience worsening renal function during treatment. There were no differences in in-hospital or post-discharge clinical outcomes. Conclusions In patients hospitalized with AHF, dyspnea, and congestion, the addition of tolvaptan to a standardized furosemide regimen did not improve the number of responders at 24 hours despite greater weight loss and fluid loss.
Skeletal muscle Akt activity stimulates muscle growth and imparts resistance to obesity, glucose intolerance and fatty liver disease. We recently found that ursolic acid increases skeletal muscle Akt ...activity and stimulates muscle growth in non-obese mice. Here, we tested the hypothesis that ursolic acid might increase skeletal muscle Akt activity in a mouse model of diet-induced obesity. We studied mice that consumed a high fat diet lacking or containing ursolic acid. In skeletal muscle, ursolic acid increased Akt activity, as well as downstream mRNAs that promote glucose utilization (hexokinase-II), blood vessel recruitment (Vegfa) and autocrine/paracrine IGF-I signaling (Igf1). As a result, ursolic acid increased skeletal muscle mass, fast and slow muscle fiber size, grip strength and exercise capacity. Interestingly, ursolic acid also increased brown fat, a tissue that shares developmental origins with skeletal muscle. Consistent with increased skeletal muscle and brown fat, ursolic acid increased energy expenditure, leading to reduced obesity, improved glucose tolerance and decreased hepatic steatosis. These data support a model in which ursolic acid reduces obesity, glucose intolerance and fatty liver disease by increasing skeletal muscle and brown fat, and suggest ursolic acid as a potential therapeutic approach for obesity and obesity-related illness.
While cilia are recognized as important signaling organelles, the extent of ciliary functions remains unknown because of difficulties in cataloguing proteins from mammalian primary cilia. We present ...a method that readily captures rapid snapshots of the ciliary proteome by selectively biotinylating ciliary proteins using a cilia-targeted proximity labeling enzyme (cilia-APEX). Besides identifying known ciliary proteins, cilia-APEX uncovered several ciliary signaling molecules. The kinases PKA, AMPK, and LKB1 were validated as bona fide ciliary proteins and PKA was found to regulate Hedgehog signaling in primary cilia. Furthermore, proteomics profiling of Ift27/Bbs19 mutant cilia correctly detected BBSome accumulation inside Ift27−/− cilia and revealed that β-arrestin 2 and the viral receptor CAR are candidate cargoes of the BBSome. This work demonstrates that proximity labeling can be applied to proteomics of non-membrane-enclosed organelles and suggests that proteomics profiling of cilia will enable a rapid and powerful characterization of ciliopathies.
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•APEX labeling enables proteomic analyses of a non-membrane-enclosed compartment•Cilia-APEX identifies the kinases PKA, AMPK, and LKB1 in primary cilia•PKA functions inside cilia to phosphorylate GLI3 and regulate Hedgehog signaling•Proteomic profiling of Ift27/Bbs19 cilia detects ciliary accumulation of BBSome
Primary cilia organize cellular signaling events in a specialized microenvironment. Mick et al. apply proximity labeling using cilia-APEX to study the ciliary proteome. They uncover unexpected signaling molecules, including kinases PKA and AMPK, inside cilia and further use a proteomic profiling approach to unravel molecular defects of Ift27/Bbs19 mutant cilia.
Modulation of the efficiency with which leaves convert absorbed light to photochemical energy intrinsic efficiency of open photosystem II (PSII) centers, as the ratio of variable to maximal ...chlorophyll fluorescence as well as leaf xanthophyll composition (interconversions of the xanthophyll cycle pigments violaxanthin and zeaxanthin) were characterized throughout single days and nights to entire seasons in plants growing naturally in contrasting light and temperature environments. All pronounced decreases of intrinsic PSII efficiency took place in the presence of zeaxanthin. The reversibility of these PSII efficiency changes varied widely, ranging from reversible-within-seconds (in a vine experiencing multiple sunflecks under a eucalypt canopy) to apparently permanently locked-in for entire seasons (throughout the whole winter in a subalpine conifer forest at 3,000 m). While close association between low intrinsic PSII efficiency and zeaxanthin accumulation was ubiquitous, accompanying features (such as trans-thylakoid pH gradient, thylakoid protein composition, and phosphorylation) differed among contrasting conditions. The strongest and longest-lasting depressions in intrinsic PSII efficiency were seen in the most stress-tolerant species. Evergreens, in particular, showed the most pronounced modulation of PSII efficiency and thermal dissipation, and are therefore suggested as model species for the study of photoprotection. Implications of the responses of field-grown plants in nature for mechanistic models are discussed.
The natriuretic peptides are biochemical markers of heart failure (HF) severity and predictors of adverse outcomes. Smaller studies have evaluated adjusting HF therapy based on natriuretic peptide ...levels ("guided therapy") with inconsistent results.
To determine whether an amino-terminal pro-B-type natriuretic peptide (NT-proBNP)-guided treatment strategy improves clinical outcomes vs usual care in high-risk patients with HF and reduced ejection fraction (HFrEF).
The Guiding Evidence Based Therapy Using Biomarker Intensified Treatment in Heart Failure (GUIDE-IT) study was a randomized multicenter clinical trial conducted between January 16, 2013, and September 20, 2016, at 45 clinical sites in the United States and Canada. This study planned to randomize 1100 patients with HFrEF (ejection fraction ≤40%), elevated natriuretic peptide levels within the prior 30 days, and a history of a prior HF event (HF hospitalization or equivalent) to either an NT-proBNP-guided strategy or usual care.
Patients were randomized to either an NT-proBNP-guided strategy or usual care. Patients randomized to the guided strategy (n = 446) had HF therapy titrated with the goal of achieving a target NT-proBNP of less than 1000 pg/mL. Patients randomized to usual care (n = 448) had HF care in accordance with published guidelines, with emphasis on titration of proven neurohormonal therapies for HF. Serial measurement of NT-proBNP testing was discouraged in the usual care group.
The primary end point was the composite of time-to-first HF hospitalization or cardiovascular mortality. Prespecified secondary end points included all-cause mortality, total hospitalizations for HF, days alive and not hospitalized for cardiovascular reasons, the individual components on the primary end point, and adverse events.
The data and safety monitoring board recommended stopping the study for futility when 894 (median age, 63 years; 286 32% women) of the planned 1100 patients had been enrolled with follow-up for a median of 15 months. The primary end point occurred in 164 patients (37%) in the biomarker-guided group and 164 patients (37%) in the usual care group (adjusted hazard ratio HR, 0.98; 95% CI, 0.79-1.22; P = .88). Cardiovascular mortality was 12% (n = 53) in the biomarker-guided group and 13% (n = 57) in the usual care group (HR, 0.94; 95% CI; 0.65-1.37; P = .75). None of the secondary end points nor the decreases in the NT-proBNP levels achieved differed significantly between groups.
In high-risk patients with HFrEF, a strategy of NT-proBNP-guided therapy was not more effective than a usual care strategy in improving outcomes.
clinicaltrials.gov Identifier: NCT01685840.
Approximately one-third of global CO2 fixation is performed by eukaryotic algae. Nearly all algae enhance their carbon assimilation by operating a CO2-concentrating mechanism (CCM) built around an ...organelle called the pyrenoid, whose protein composition is largely unknown. Here, we developed tools in the model alga Chlamydomonas reinhardtii to determine the localizations of 135 candidate CCM proteins and physical interactors of 38 of these proteins. Our data reveal the identity of 89 pyrenoid proteins, including Rubisco-interacting proteins, photosystem I assembly factor candidates, and inorganic carbon flux components. We identify three previously undescribed protein layers of the pyrenoid: a plate-like layer, a mesh layer, and a punctate layer. We find that the carbonic anhydrase CAH6 is in the flagella, not in the stroma that surrounds the pyrenoid as in current models. These results provide an overview of proteins operating in the eukaryotic algal CCM, a key process that drives global carbon fixation.
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•Localizations and physical interactions of candidate CO2-concentrating mechanism (CCM) proteins were determined•The data reveal three previously undescribed pyrenoid layers and 89 pyrenoid proteins•Plasma membrane inorganic carbon transporters LCI1 and HLA3 form a complex•Carbonic anhydrase 6 localizes to the flagella, changing the model of the CCM
Microscopy and proteomic analyses reveal three previously unknown layers of the pyrenoid, the cellular organelle in algae responsible for one-third of global CO2 fixation
The TRiC/CCT chaperonin is a 1-MDa hetero-oligomer of 16 subunits that assists the folding of proteins in eukaryotes. Low-resolution structural studies confirmed the TRiC particle to be composed of ...two stacked octameric rings enclosing a folding cavity. The exact arrangement of the different proteins in the rings underlies the functionality of TRiC and is likely to be conserved across all eukaryotes. Yet despite its importance it has not been determined conclusively, mainly because the different subunits appear nearly identical under low resolution. This work successfully addresses the arrangement problem by the emerging technique of cross-linking, mass spectrometry, and modeling. We cross-linked TRiC under native conditions with a cross-linker that is primarily reactive toward exposed lysine side chains that are spatially close in the context of the particle. Following digestion and mass spectrometry we were able to identify over 60 lysine pairs that underwent cross-linking, thus providing distance restraints between specific residues in the complex. Independently of the cross-link set, we constructed 40,320 (= 8 factorial) computational models of the TRiC particle, which exhaustively enumerate all the possible arrangements of the different subunits. When we assessed the compatibility of each model with the cross-link set, we discovered that one specific model is significantly more compatible than any other model. Furthermore, bootstrapping analysis confirmed that this model is 10 times more likely to result from this cross-link set than the next best-fitting model. Our subunit arrangement is very different than any of the previously reported models and changes the context of existing and future findings on TRiC.
In most mammalian cells, insulin and glucocorticoids promote anabolism and catabolism, respectively. Whereas the opposing effects of insulin and glucocorticoids on catabolic gene expression have been ...explained at the molecular level, comparatively little is known about how these hormones alter anabolic gene expression. These studies identify ATF4 as an anabolic transcription factor that is repressed by glucocorticoids and induced by insulin. Insulin-mediated induction of ATF4 required the mammalian target of rapamycin complex 1, was required for the activation of a genetic program for the cellular uptake of essential amino acids and the synthesis of nonessential amino acids and aminoacyl-tRNAs, and was coupled to the repression of Foxo-dependent genes needed for protein and lipid catabolism. These results suggest that ATF4 plays a central role in hormonal regulation of amino acid and protein anabolism by coupling amino acid uptake and synthesis, as well as the generation of charged tRNAs, to mammalian target of rapamycin complex 1-mediated mRNA translation.
Advanced heart failure (HF) is characterized by high morbidity and mortality. Conventional therapy may not sufficiently reduce patient suffering and maximize quality of life.
The authors investigated ...whether an interdisciplinary palliative care intervention in addition to evidence-based HF care improves certain outcomes.
The authors randomized 150 patients with advanced HF between August 15, 2012, and June 25, 2015, to usual care (UC) (n = 75) or UC plus a palliative care intervention (UC + PAL) (n = 75) at a single center. Primary endpoints were 2 quality-of-life measurements, the Kansas City Cardiomyopathy Questionnaire (KCCQ) overall summary and the Functional Assessment of Chronic Illness Therapy-Palliative Care scale (FACIT-Pal), assessed at 6 months. Secondary endpoints included assessments of depression and anxiety (measured via the Hospital Anxiety and Depression Scale HADS), spiritual well-being (measured via the FACIT-Spiritual Well-Being scale FACIT-Sp), hospitalizations, and mortality.
Patients randomized to UC + PAL versus UC alone had clinically significant incremental improvement in KCCQ and FACIT-Pal scores from randomization to 6 months (KCCQ difference = 9.49 points, 95% confidence interval CI: 0.94 to 18.05, p = 0.030; FACIT-Pal difference = 11.77 points, 95% CI: 0.84 to 22.71, p = 0.035). Depression improved in UC + PAL patients (HADS-depression difference = -1.94 points; p = 0.020) versus UC-alone patients, with similar findings for anxiety (HADS-anxiety difference = -1.83 points; p = 0.048). Spiritual well-being was improved in UC + PAL versus UC-alone patients (FACIT-Sp difference = 3.98 points; p = 0.027). Randomization to UC + PAL did not affect rehospitalization or mortality.
An interdisciplinary palliative care intervention in advanced HF patients showed consistently greater benefits in quality of life, anxiety, depression, and spiritual well-being compared with UC alone. (Palliative Care in Heart Failure PAL-HF; NCT01589601).
Muscle wasting resulting wholly or in part from disuse represents a serious medical complication that, when prolonged, can increase morbidity and mortality. Although much knowledge has been gained ...over the past half century, the underlying etiology by which disuse alters muscle proteostasis remains enigmatic. Multidisciplinary and novel methodologies are needed to fill gaps and overcome barriers to improved patient care. The present review highlights seminal concepts from a symposium at Experimental Biology 2016. These proceedings focus on 1) the role of insulin resistance in mediating disuse-induced changes in muscle protein synthesis (MPS) and breakdown (MPB), as well as cross-talk between carbohydrate and protein metabolism; 2) the relative importance of MPS/MPB in mediating involuntary muscle loss in humans and animals; 3) interpretative limitations associated with MPS/MPB "markers," e.g., MuRF1/MAFbx mRNA; and finally, 4) how OMIC technologies can be leveraged to identify molecular pathways (e.g., ATF4, p53, p21) mediating disuse atrophy. This perspective deals primarily with "simple atrophy" due to unloading. Nonetheless, it is likely that disuse is a pervasive contributor to muscle wasting associated with catabolic disease-related atrophy (i.e., due to associated sedentary behaviour of disease burden). Key knowledge gaps and challenges are identified to stimulate discussion and identify opportunities for translational research. Data from animal and human studies highlight both similarities and differences. Integrated preclinical and clinical research is encouraged to better understand the metabolic and molecular underpinnings and translational relevance,for disuse atrophy. These approaches are crucial to clinically prevent or reverse muscle atrophy, thereby reestablishing homeostasis and recovery.
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