Vigorous Exercise in Patients with Hypertrophic Cardiomyopathy.

ABSTRACT: Hypertrophic cardiomyopathy is a genetic heart condition occurring in up to 1 in 200 patients in the United States, many of whom are young and otherwise healthy. This condition puts those affected at increased risk for adverse cardiac outcomes, including sudden cardiac arrest and death, with particular concern for this to occur during exercise and other forms of exertion. Recent studies aimed at evaluating the risk of exercise in hypertrophic cardiomyopathy patients have suggested that moderate and even vigorous exercise may be safe for certain patients. Clinical guidelines are changing to reflect this recent information and to encourage a shared decision-making approach, which can allow more hypertrophic cardiomyopathy patients to participate in health-promoting exercise activities.

Attack behaviour in naive gyrfalcons is modelled by the same guidance law as in peregrine falcons, but at a lower guidance gain.

The aerial hunting behaviours of birds are strongly influenced by flight morphology and ecology, but little is known of how this relates to the behavioural algorithms guiding flight. Here, we used GPS loggers to record the attack trajectories of captive-bred gyrfalcons (Falco rusticolus) during their maiden flights against robotic aerial targets, which we compared with existing flight data from peregrine falcons (Falco peregrinus). The attack trajectories of both species were well modelled by a proportional navigation (PN) guidance law, which commands turning in proportion to the angular rate of the line-of-sight to target, at a guidance gain N However, naive gyrfalcons operate at significantly lower values of N than peregrine falcons, producing slower turning and a longer path to intercept. Gyrfalcons are less manoeuvrable than peregrine falcons, but physical constraint is insufficient to explain the lower values of N we found, which may reflect either the inexperience of the individual birds or ecological adaptation at the species level. For example, low values of N promote the tail-chasing behaviour that is typical of wild gyrfalcons and which apparently serves to tire their prey in a prolonged high-speed pursuit. Likewise, during close pursuit of typical fast evasive prey, PN will be less prone to being thrown off by erratic target manoeuvres at low guidance gain. The fact that low-gain PN successfully models the maiden attack flights of gyrfalcons suggests that this behavioural algorithm is embedded in a guidance pathway ancestral to the clade containing gyrfalcons and peregrine falcons, though perhaps with much deeper evolutionary origins.

Maternal immune activation with staphylococcal enterotoxin A produces unique behavioral changes in C57BL/6 mouse offspring.

Stimulation of the immune system during pregnancy, known as maternal immune activation (MIA), can cause long-lasting neurobiological and behavioral changes in the offspring. This phenomenon has been implicated in the etiology of developmental psychiatric disorders, such as autism and schizophrenia. Much of this evidence is predicated on animal models using bacterial agents such as LPS and/or viral mimics such as Poly I:C, both of which act through toll-like receptors. However, fewer studies have examined the role of direct activation of maternal T-cells during pregnancy using microbial agents. Bacterial superantigens, such as Staphylococcal Enterotoxin A and B (SEA; SEB), are microbial proteins that activate CD4+ T-cells and cause prominent T-cell proliferation and cytokine production. We injected pregnant and non-pregnant adult female C57BL/6 mice with 200 µg/Kg of SEA, SEB, or 0.9% saline, and measured splenic T-cell-derived cytokine concentrations (viz., IL-2, IFN-γ, IL-6, and IL-4) 2 h later; animals injected with SEA were also measured for splenic concentrations of TNF-α and IL-17A. Half of the injected pregnant animals were brought to term, and their offspring were tested on a series of behavioral tasks starting at six weeks of age (postnatal day 42 [P42]). These tasks included social interaction, the elevated plus maze (EPM), an open field and object recognition (OR) task, prepulse inhibition (PPI) of sensorimotor gating, and the Morris water maze (MWM). Results showed that SEA and SEB induced significant concentrations of all measured cytokines, and in particular IFN-γ, although cytokine responses were greater following SEA exposure. In addition, pregnancy induced an inhibitory effect on cytokine production. Behavioral results showed distinct phenotypes among offspring from SEA- or SEB-injected mothers, very likely due to differences in the magnitude of cytokines generated in response to each toxin. Offspring from SEA-injected mothers displayed modest decreases in social behavior, but increased anxiety, locomotion, interest in a novel object, and short-term spatial memory, while offspring of SEB-injected mothers only exhibited increased anxiety and locomotion. There were no deficits in PPI, which was actually pronounced in SEA and SEB offspring. Overall, the novel use of SEA and SEB as prenatal immune challenges elicited distinct behavioral profiles in the offspring that both mirrors and diverges from previous models of maternal immune activation in important ways. We conclude that superantigen-induced T-cell-mediated maternal immune activation is a valid and valuable model for studying and expanding our understanding of the effects of prenatal immune challenge on neurodevelopmental and behavioral alterations in offspring.

Generation of HER2-specific antibody immunity during trastuzumab adjuvant therapy associates with reduced relapse in resected HER2 breast cancer.

BACKGROUND: Resected HER2 breast cancer patients treated with adjuvant trastuzumab and chemotherapy have superior survival compared to patients treated with chemotherapy alone. We previously showed that trastuzumab and chemotherapy induce HER2-specific antibodies which correlate with improved survival in HER2 metastatic breast cancer patients. It remains unclear whether the generation of immunity required trastuzumab and whether endogenous antibody immunity is associated with improved disease-free survival in the adjuvant setting. In this study, we addressed this question by analyzing serum anti-HER2 antibodies from a subset of patients enrolled in the NCCTG trial N9831, which includes an arm (Arm A) in which trastuzumab was not used. Arms B and C received trastuzumab sequentially or concurrently to chemotherapy, respectively. METHODS: Pre-and post-treatment initiation sera were obtained from 50 women enrolled in N9831. Lambda IgG antibodies (to avoid detection of trastuzumab) to HER2 were measured and compared between arms and with disease-free survival. RESULTS: Prior to therapy, across all three arms, N9831 patients had similar mean anti-HER2 IgG levels. Following treatment, the mean levels of antibodies increased in the trastuzumab arms but not the chemotherapy-only arm. The proportion of patients who demonstrated antibodies increased by 4% in Arm A and by 43% in the Arms B and C combined (p = 0.003). Cox modeling demonstrated that larger increases in antibodies were associated with improved disease-free survival in all patients (HR = 0.23; p = 0.04). CONCLUSIONS: These results show that the increased endogenous antibody immunity observed in adjuvant patients treated with combination trastuzumab and chemotherapy is clinically significant, in view of its correlation with improved disease-free survival. The findings may have important implications for predicting treatment outcomes in patients treated with trastuzumab in the adjuvant setting. TRIAL REGISTRATION: ClinicalTrials.gov, NCT00005970 . Registered on July 5, 2000.

Frataxin Accelerates [2Fe-2S] Cluster Formation on the Human Fe-S Assembly Complex.

Iron-sulfur (Fe-S) clusters function as protein cofactors for a wide variety of critical cellular reactions. In human mitochondria, a core Fe-S assembly complex [called SDUF and composed of NFS1, ISD11, ISCU2, and frataxin (FXN) proteins] synthesizes Fe-S clusters from iron, cysteine sulfur, and reducing equivalents and then transfers these intact clusters to target proteins. In vitro assays have relied on reducing the complexity of this complicated Fe-S assembly process by using surrogate electron donor molecules and monitoring simplified reactions. Recent studies have concluded that FXN promotes the synthesis of [4Fe-4S] clusters on the mammalian Fe-S assembly complex. Here the kinetics of Fe-S synthesis reactions were determined using different electron donation systems and by monitoring the products with circular dichroism and absorbance spectroscopies. We discovered that common surrogate electron donor molecules intercepted Fe-S cluster intermediates and formed high-molecular weight species (HMWS). The HMWS are associated with iron, sulfide, and thiol-containing proteins and have properties of a heterogeneous solubilized mineral with spectroscopic properties remarkably reminiscent of those of [4Fe-4S] clusters. In contrast, reactions using physiological reagents revealed that FXN accelerates the formation of [2Fe-2S] clusters rather than [4Fe-4S] clusters as previously reported. In the preceding paper [Fox, N. G., et al. (2015) Biochemistry 54, DOI: 10.1021/bi5014485], [2Fe-2S] intermediates on the SDUF complex were shown to readily transfer to uncomplexed ISCU2 or apo acceptor proteins, depending on the reaction conditions. Our results indicate that FXN accelerates a rate-limiting sulfur transfer step in the synthesis of [2Fe-2S] clusters on the human Fe-S assembly complex.

The Human Iron-Sulfur Assembly Complex Catalyzes the Synthesis of [2Fe-2S] Clusters on ISCU2 That Can Be Transferred to Acceptor Molecules.

Iron-sulfur (Fe-S) clusters are essential protein cofactors for most life forms. In human mitochondria, the core Fe-S biosynthetic enzymatic complex (called SDUF) consists of NFS1, ISD11, ISCU2, and frataxin (FXN) protein components. Few mechanistic details about how this complex synthesizes Fe-S clusters and how these clusters are delivered to targets are known. Here circular dichroism and Mössbauer spectroscopies were used to reveal details of the Fe-S cluster assembly reaction on the SDUF complex. SDUF reactions generated [2Fe-2S] cluster intermediates that readily converted to stable [2Fe-2S] clusters bound to uncomplexed ISCU2. Similar reactions that included the apo Fe-S acceptor protein human ferredoxin (FDX1) resulted in formation of [2Fe-2S]-ISCU2 rather than [2Fe-2S]-FDX1. Subsequent addition of dithiothreitol (DTT) induced transfer of the cluster from ISCU2 to FDX1, suggesting that [2Fe-2S]-ISCU2 is an intermediate. Reactions that initially included DTT rapidly generated [2Fe-2S]-FDX1 and bypassed formation of [2Fe-2S]-ISCU2. In the absence of apo-FDX1, incubation of [2Fe-2S]-ISCU2 with DTT generated [4Fe-4S]-ISCU2 species. Together, these results conflict with a recent report of stable [4Fe-4S] cluster formation on the SDUF complex. Rather, they support a model in which SDUF builds transient [2Fe-2S] cluster intermediates that generate clusters on sulfur-containing molecules, including uncomplexed ISCU2. Additional small molecule or protein factors are required for the transfer of these clusters to Fe-S acceptor proteins or the synthesis of [4Fe-4S] clusters.

Human frataxin activates Fe-S cluster biosynthesis by facilitating sulfur transfer chemistry.

Iron-sulfur clusters are ubiquitous protein cofactors with critical cellular functions. The mitochondrial Fe-S assembly complex, which consists of the cysteine desulfurase NFS1 and its accessory protein (ISD11), the Fe-S assembly protein (ISCU2), and frataxin (FXN), converts substrates l-cysteine, ferrous iron, and electrons into Fe-S clusters. The physiological function of FXN has received a tremendous amount of attention since the discovery that its loss is directly linked to the neurodegenerative disease Friedreich's ataxia. Previous in vitro results revealed a role for human FXN in activating the cysteine desulfurase and Fe-S cluster biosynthesis activities of the Fe-S assembly complex. Here we present radiolabeling experiments that indicate FXN accelerates the accumulation of sulfur on ISCU2 and that the resulting persulfide species is viable in the subsequent synthesis of Fe-S clusters. Additional mutagenesis, enzyme kinetic, UV-visible, and circular dichroism spectroscopic studies suggest conserved ISCU2 residue C104 is critical for FXN activation, whereas C35, C61, and C104 are all essential for Fe-S cluster formation on the assembly complex. These results cannot be fully explained by the hypothesis that FXN functions as an iron donor for Fe-S cluster biosynthesis, and further support an allosteric regulator role for FXN. Together, these results lead to an activation model in which FXN accelerates persulfide formation on NFS1 and favors a helix-to-coil interconversion on ISCU2 that facilitates the transfer of sulfur from NFS1 to ISCU2 as an initial step in Fe-S cluster biosynthesis.

Probing the early development of visual working memory capacity with functional near-infrared spectroscopy.

Visual working memory (VWM) is a core cognitive system with a highly limited capacity. The present study is the first to examine VWM capacity limits in early development using functional neuroimaging. We recorded optical neuroimaging data while 3- and 4-year-olds completed a change detection task where they detected changes in the shapes of objects after a brief delay. Near-infrared sources and detectors were placed over the following 10-20 positions: F3 and F5 in left frontal cortex, F4 and F6 in right frontal cortex, P3 and P5 in left parietal cortex, and P4 and P6 in right parietal cortex. The first question was whether we would see robust task-specific activation of the frontal-parietal network identified in the adult fMRI literature. This was indeed the case: three left frontal channels and 11 of 12 parietal channels showed a statistically robust difference between the concentration of oxygenated and deoxygenated hemoglobin following the presentation of the sample array. Moreover, four channels in the left hemisphere near P3, P5, and F5 showed a robust increase as the working memory load increased from 1 to 3 items. Notably, the hemodynamic response did not asymptote at 1-2 items as expected from previous fMRI studies with adults. Finally, 4-year-olds showed a more robust parietal response relative to 3-year-olds, and an increasing sensitivity to the memory load manipulation. These results demonstrate that fNIRS is an effective tool to study the neural processes that underlie the early development of VWM capacity.

Invention of MK-7845, a SARS-CoV-2 3CL Protease Inhibitor Employing a Novel Difluorinated Glutamine Mimic.

As SARS-CoV-2 continues to circulate, antiviral treatments are needed to complement vaccines. The virus's main protease, 3CLPro, is an attractive drug target in part because it recognizes a unique cleavage site, which features a glutamine residue at the P1 position and is not utilized by human proteases. Herein, we report the invention of MK-7845, a novel reversible covalent 3CLPro inhibitor. While most covalent inhibitors of SARS-CoV-2 3CLPro reported to date contain an amide as a Gln mimic at P1, MK-7845 bears a difluorobutyl substituent at this position. SAR analysis and X-ray crystallographic studies indicate that this group interacts with His163, the same residue that forms a hydrogen bond with the amide substituents typically found at P1. In addition to promising in vivo efficacy and an acceptable projected human dose with unboosted pharmacokinetics, MK-7845 exhibits favorable properties for both solubility and absorption that may be attributable to the unusual difluorobutyl substituent.

Molecular engineering of organophosphate hydrolysis activity from a weak promiscuous lactonase template.

Rapid evolution of enzymes provides unique molecular insights into the remarkable adaptability of proteins and helps to elucidate the relationship between amino acid sequence, structure, and function. We interrogated the evolution of the phosphotriesterase from Pseudomonas diminuta (PdPTE), which hydrolyzes synthetic organophosphates with remarkable catalytic efficiency. PTE is thought to be an evolutionarily "young" enzyme, and it has been postulated that it has evolved from members of the phosphotriesterase-like lactonase (PLL) family that show promiscuous organophosphate-degrading activity. Starting from a weakly promiscuous PLL scaffold (Dr0930 from Deinococcus radiodurans ), we designed an extremely efficient organophosphate hydrolase (OPH) with broad substrate specificity using rational and random mutagenesis in combination with in vitro activity screening. The OPH activity for seven organophosphate substrates was simultaneously enhanced by up to 5 orders of magnitude, achieving absolute values of catalytic efficiencies up to 10(6) M(-1) s(-1). Structural and computational analyses identified the molecular basis for the enhanced OPH activity of the engineered PLL variants and demonstrated that OPH catalysis in PdPTE and the engineered PLL differ significantly in the mode of substrate binding.

Outcomes of Intravenous Push versus Intermittent Infusion Administration of Cefepime in Critically Ill Patients.

The equivalence of intravenous push (IVP) and piggyback (IVPB) administration has not been evaluated in the critically ill population for most medications, but it is especially relevant for antibiotics, such as cefepime, that exhibit time-dependent bactericidal activity. A single center, retrospective, observational pre/post-protocol change study included critically ill adults who received cefepime as empiric therapy between August 2015 and 2021. The primary outcome was treatment failure, which was defined as a composite of escalation of antibiotic regimen or all-cause mortality. Secondary outcomes included adverse drug events, days of cefepime therapy, total days of antibiotic therapy, and ICU and hospital length of stay. Outcomes were compared using Chi-squared, Mann Whitney U, and binary logistic regression as appropriate. A total of 285 patients were included: 87 IVPB and 198 IVP. Treatment failure occurred in 18% (n = 16) of the IVPB group and 27% (n = 54) of the IVP group (p = 0.109). There were no significant differences in secondary outcomes. Longer duration of antibiotics (odds ratio [OR] 1.057, 95% confidence interval [CI] 1.013-1.103), SOFA score (OR 1.269, 95% CI 1.154-1.397) and IVP administration of cefepime (OR 2.370, 95% CI 1.143-4.914) were independently associated with treatment failure. Critically ill patients who received IVP cefepime were more likely to experience treatment failure in an adjusted analysis. The current practice of IVP cefepime should be reevaluated, as it may not provide similar clinical outcomes in the critically ill population.

Enzymes for the homeland defense: optimizing phosphotriesterase for the hydrolysis of organophosphate nerve agents.

Phosphotriesterase (PTE) from soil bacteria is known for its ability to catalyze the detoxification of organophosphate pesticides and chemical warfare agents. Most of the organophosphate chemical warfare agents are a mixture of two stereoisomers at the phosphorus center, and the S(P)-enantiomers are significantly more toxic than the R(P)-enantiomers. In previous investigations, PTE variants were created through the manipulation of the substrate binding pockets and these mutants were shown to have greater catalytic activities for the detoxification of the more toxic S(P)-enantiomers of nerve agent analogues for GB, GD, GF, VX, and VR than the less toxic R(P)-enantiomers. In this investigation, alternate strategies were employed to discover additional PTE variants with significant improvements in catalytic activities relative to that of the wild-type enzyme. Screening and selection techniques were utilized to isolate PTE variants from randomized libraries and site specific modifications. The catalytic activities of these newly identified PTE variants toward the S(P)-enantiomers of chromophoric analogues of GB, GD, GF, VX, and VR have been improved up to 15000-fold relative to that of the wild-type enzyme. The X-ray crystal structures of the best PTE variants were determined. Characterization of these mutants with the authentic G-type nerve agents has confirmed the expected improvements in catalytic activity against the most toxic enantiomers of GB, GD, and GF. The values of k(cat)/K(m) for the H257Y/L303T (YT) mutant for the hydrolysis of GB, GD, and GF were determined to be 2 × 10(6), 5 × 10(5), and 8 × 10(5) M(-1) s(-1), respectively. The YT mutant is the most proficient enzyme reported thus far for the detoxification of G-type nerve agents. These results support a combinatorial strategy of rational design and directed evolution as a powerful tool for the discovery of more efficient enzymes for the detoxification of organophosphate nerve agents.

Coincidence Analysis: A Novel Approach to Modeling Nurses' Workplace Experience.

OBJECTIVES: The purpose of this study is to identify combinations of workplace conditions that uniquely differentiate high, medium, and low registered nurse (RN) ratings of appropriateness of patient assignment during daytime intensive care unit (ICU) work shifts. METHODS: A collective case study design and coincidence analysis were employed to identify combinations of workplace conditions that link directly to high, medium, and low RN perception of appropriateness of patient assignment at a mid-shift time point. RN members of the study team hypothesized a set of 55 workplace conditions as potential difference makers through the application of theoretical and empirical knowledge. Conditions were derived from data exported from electronic systems commonly used in nursing care. RESULTS: Analysis of 64 cases (25 high, 24 medium, and 15 low) produced three models, one for each level of the outcome. Each model contained multiple pathways to the same outcome. The model for "high" appropriateness was the simplest model with two paths to the outcome and a shared condition across pathways. The first path comprised of the absence of overtime and a before-noon patient discharge or transfer, and the second path comprised of the absence of overtime and RN assignment to a single ICU patient. CONCLUSION: Specific combinations of workplace conditions uniquely distinguish RN perception of appropriateness of patient assignment at a mid-shift time point, and these difference-making conditions provide a foundation for enhanced observability of nurses' work experience during hospital work shifts. This study illuminates the complexity of assessing nursing work system status by revealing that multiple paths, comprised of multiple conditions, can lead to the same outcome. Operational decision support tools may best reflect the complex adaptive nature of the work systems they intend to support by utilizing methods that accommodate both causal complexity and equifinality.

Real-world use of inhaled nitric oxide therapy in patients with COVID-19 and mild-to-moderate acute respiratory distress syndrome.

Background: Inhaled nitric oxide (iNO) has been studied in patients with severe acute respiratory distress syndrome (ARDS) due to COVID-19 when it may be too late to impact disease course. This article aims to describe real-world iNO use and outcomes in patients with COVID-19 with mild-to-moderate ARDS in the United States. Methods: This was a retrospective medical chart review study that included patients who were ≥18 years old, hospitalized for COVID-19, met the Berlin ARDS definition, received iNO for ≥24 hours continuously during hospitalization, and had a partial pressure of oxygen (PaO2)/fraction of inspired oxygen (FiO2) ratio (P/F ratio) of >100 to ≤300 mmHg at iNO initiation. Outcomes included oxygenation parameters, physician-rated Clinical Global Impression-Improvement (CGI-I) scale scores, and adverse events. Response to iNO was defined as >20% improvement in P/F ratio. Results: Thirty-seven patients at six sites were included. A P/F ratio of ≤100 was the most common reason for exclusion (n=146; 83% of excluded patients). The mean P/F ratio (SD) increased from 136.7 (34.4) at baseline to 140.3 (53.2) at 48 hours and 151.8 (50.0) at 72 hours after iNO initiation. The response rate was 62% (n=23). During hospitalization, no patient experienced adverse events, including methemoglobinaemia, airway injury, or worsening pulmonary oedema associated with iNO. At discharge, 54.0% (n=20) of patients improved or remained stable according to the CGI-I. Conclusion: In patients hospitalized with COVID-19 and mild-to-moderate ARDS, iNO was associated with improvement in the P/F ratio with no reported toxicity. This study provides additional evidence supporting a favourable benefit-risk profile for iNO in the treatment of mild-to-moderate ARDS in patients with COVID-19 infection.

Straight and Divergent Pathways to Cognitive State: Seven Decades of Follow-Up in the British 1946 Birth Cohort.

BACKGROUND: Using the British 1946 birth cohort we previously estimated life course paths to the Addenbrooke's Cognitive Examination (ACE-III). OBJECTIVE: We now compared those whose ACE-III scores were expected, worse and better than predicted from the path model on a range of independent variables including clinical ratings of cognitive impairment and neuroimaging measures. METHODS: Predicted ACE-III scores were categorized into three groups: those with Expected (between -1.5 and 1.5 standard deviation; SD); Worse (< -1.5 SD); and Better (>1.5 SD) scores. Differences in the independent variables were then tested between these three groups. RESULTS: Compared with the Expected group, those in the Worse group showed independent evidence of progressive cognitive impairment: faster memory decline, more self-reported memory difficulties, more functional difficulties, greater likelihood of being independently rated by experienced specialist clinicians as having a progressive cognitive impairment, and a cortical thinning pattern suggestive of preclinical Alzheimer's disease. Those in the Better group showed slower verbal memory decline and absence of independently rated progressive cognitive impairment compared to the Expected group, but no differences in any of the other independent variables including the neuroimaging variables. CONCLUSION: The residual approach shows that life course features can map directly to clinical diagnoses. One future challenge is to translate this into a readily usable algorithm to identify high-risk individuals in preclinical state, when preventive strategies and therapeutic interventions may be most effective.

Structure of the human frataxin-bound iron-sulfur cluster assembly complex provides insight into its activation mechanism.

The core machinery for de novo biosynthesis of iron-sulfur clusters (ISC), located in the mitochondria matrix, is a five-protein complex containing the cysteine desulfurase NFS1 that is activated by frataxin (FXN), scaffold protein ISCU, accessory protein ISD11, and acyl-carrier protein ACP. Deficiency in FXN leads to the loss-of-function neurodegenerative disorder Friedreich's ataxia (FRDA). Here the 3.2 Å resolution cryo-electron microscopy structure of the FXN-bound active human complex, containing two copies of the NFS1-ISD11-ACP-ISCU-FXN hetero-pentamer, delineates the interactions of FXN with other component proteins of the complex. FXN binds at the interface of two NFS1 and one ISCU subunits, modifying the local environment of a bound zinc ion that would otherwise inhibit NFS1 activity in complexes without FXN. Our structure reveals how FXN facilitates ISC production through stabilizing key loop conformations of NFS1 and ISCU at the protein-protein interfaces, and suggests how FRDA clinical mutations affect complex formation and FXN activation.

4'-Phosphopantetheine and long acyl chain-dependent interactions are integral to human mitochondrial acyl carrier protein function.

The mitochondrial acyl carrier protein (human ACPM, yeast Acp1) is an essential mitochondrial protein. Through binding of nascent acyl chains on the serine (S112)-bound 4'-phosphopantetheine (4'-PP) cofactor, ACPM is involved in mitochondrial fatty acid synthesis and lipoic acid biogenesis. Recently, yeast Acp1 was found to interact with several mitochondrial complexes, including the iron-sulfur (Fe-S) cluster biosynthesis and respiratory complexes, via the binding to LYRM proteins, a family of proteins involved in assembly/stability of complexes. Importantly, the interaction of LYRM proteins with Acp1 was shown to be essential in maintaining integrity of mitochondrial complexes. In human, recent structures show that ACPM binding to LYRM proteins involves acyl chains attached to the 4'-PP cofactor. Here, we performed an detailed characterization of the mitochondrial interactome of human ACPM by mass spectrometry (MS) and demonstrate the crucial role of the 4'-PP cofactor in most of ACPM interactions. Specifically, we show that ACPM interacts with endogenous Fe-S cluster complex components through binding of the LYRM protein ISD11/LYRM4. Using knockdown experiments, we further determine that ACPM is essential for the stability of mitochondrial respiratory complexes I, II and III, as well as the Fe-S cluster biosynthesis complex. Finally, using native MS and a top-down MS approach, we show that C14, C16 and C18 3-keto-acyl chains on ACPM are implicated in binding to ISD11 through analysis of the recombinant ACPM-ISD11 complex. Taken together, our data provide novel understanding of the role of 4'-PP- and long acyl chains-dependent interactions in human ACPM function.

Zinc(II) binding on human wild-type ISCU and Met140 variants modulates NFS1 desulfurase activity.

Human de novo iron-sulfur (Fe-S) assembly complex consists of cysteine desulfurase NFS1, accessory protein ISD11, acyl carrier protein ACP, scaffold protein ISCU, and allosteric activator frataxin (FXN). FXN binds the NFS1-ISD11-ACP-ISCU complex (SDAU), to activate the desulfurase activity and Fe-S cluster biosynthesis. In the absence of FXN, the NFS1-ISD11-ACP (SDA) complex was reportedly inhibited by binding of recombinant ISCU. Recent studies also reported a substitution at position Met141 on the yeast ISCU orthologue Isu, to Ile, Leu, Val, or Cys, could bypass the requirement of FXN for Fe-S cluster biosynthesis and cell viability. Here, we show that recombinant human ISCU binds zinc(II) ion, as previously demonstrated with the E. coli orthologue IscU. Surprisingly, the relative proportion between zinc-bound and zinc-depleted forms varies among purification batches. Importantly the presence of zinc in ISCU impacts SDAU desulfurase activity. Indeed, removal of zinc(II) ion from ISCU causes a moderate but significant increase in activity compared to SDA alone, and FXN can activate both zinc-depleted and zinc-bound forms of ISCU complexed to SDA. Taking into consideration the inhibition of desulfurase activity by zinc-bound ISCU, we characterized wild type ISCU and the M140I, M140L, and M140V variants under both zinc-bound and zinc-depleted conditions, and did not observe significant differences in the biochemical and biophysical properties between wild-type and variants. Importantly, in the absence of FXN, ISCU variants behaved like wild-type and did not stimulate the desulfurase activity of the SDA complex. This study therefore identifies an important regulatory role for zinc-bound ISCU in modulation of the human Fe-S assembly system in vitro and reports no 'FXN bypass' effect on mutations at position Met140 in human ISCU. Furthermore, this study also calls for caution in interpreting studies involving recombinant ISCU by taking into consideration the influence of the bound zinc(II) ion on SDAU complex activity.

The Psychological Science Accelerator: Advancing Psychology through a Distributed Collaborative Network.

Concerns have been growing about the veracity of psychological research. Many findings in psychological science are based on studies with insufficient statistical power and nonrepresentative samples, or may otherwise be limited to specific, ungeneralizable settings or populations. Crowdsourced research, a type of large-scale collaboration in which one or more research projects are conducted across multiple lab sites, offers a pragmatic solution to these and other current methodological challenges. The Psychological Science Accelerator (PSA) is a distributed network of laboratories designed to enable and support crowdsourced research projects. These projects can focus on novel research questions, or attempt to replicate prior research, in large, diverse samples. The PSA's mission is to accelerate the accumulation of reliable and generalizable evidence in psychological science. Here, we describe the background, structure, principles, procedures, benefits, and challenges of the PSA. In contrast to other crowdsourced research networks, the PSA is ongoing (as opposed to time-limited), efficient (in terms of re-using structures and principles for different projects), decentralized, diverse (in terms of participants and researchers), and inclusive (of proposals, contributions, and other relevant input from anyone inside or outside of the network). The PSA and other approaches to crowdsourced psychological science will advance our understanding of mental processes and behaviors by enabling rigorous research and systematically examining its generalizability.

Quantifying research output on poverty and non-communicable disease behavioural risk factors in low-income and lower middle-income countries: a bibliometric analysis.

OBJECTIVES: Low-income and lower middle-income countries (LLMICs) bear a disproportionate burden of non-communicable diseases (NCDs). WHO has repeatedly called for more research on poverty and NCDs in these settings, but the current situation remains unquantified. We aimed to assess research output on poverty and NCD risk factors from these countries in relation to upper middle-income and high-income countries. DESIGN: Bibliometric analysis of primary research published between 1 January 1990 and 4 May 2017. We searched 13 databases, combining terms for poverty and NCD behavioural risk factors (tobacco, alcohol, diet and physical activity). Independent dual review was used to screen titles, abstracts and full papers. Two-tailed t-testing and multiple linear regression analyses were used to compare differences in means. OUTCOMES: (1) Proportion of lead authors affiliated with institutions based in high and upper middle-income countries vs LLMICs. (2) Mean number of citations for publications from each region. (3) Mean journal impact factor for studies from each region. RESULTS: Ninety-one (67%) of the 136 included studies were led by scientists affiliated with LLMIC-based institutions. These authors represented 17/83 LLMICs (20%), and their studies garnered 4.8 fewer citations per paper than studies led by high-income and upper middle-income-affiliated authors; however, this finding was non-significant (P=0.67). Papers led by authors based in high-income and upper middle-income countries were published in journals with a mean impact factor 3.1 points higher than those from LLMICs (4.9 vs 1.7) adjusting for year of publication and number of citations (P<0.001). CONCLUSIONS: Most poverty and NCD risk factor research is led by authors from a small number of LLMICs. These studies are being published in relatively low-impact journals, and the vast majority of LLMICs are not producing any research in this area that is vital to their social and economic development. The paucity of domestic evidence must be addressed to inform global policy.