The SARS-CoV-2 spike (S) protein variant D614G supplanted the ancestral virus worldwide, reaching near fixation in a matter of months. Here we show that D614G was more infectious than the ancestral ...form on human lung cells, colon cells, and on cells rendered permissive by ectopic expression of human ACE2 or of ACE2 orthologs from various mammals, including Chinese rufous horseshoe bat and Malayan pangolin. D614G did not alter S protein synthesis, processing, or incorporation into SARS-CoV-2 particles, but D614G affinity for ACE2 was reduced due to a faster dissociation rate. Assessment of the S protein trimer by cryo-electron microscopy showed that D614G disrupts an interprotomer contact and that the conformation is shifted toward an ACE2 binding-competent state, which is modeled to be on pathway for virion membrane fusion with target cells. Consistent with this more open conformation, neutralization potency of antibodies targeting the S protein receptor-binding domain was not attenuated.
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•The SARS-CoV-2 D614G S protein variant supplanted the ancestral virus in people•D614G increases infectivity on human lung cells or cells with bat or pangolin ACE2•D614G is potently neutralized by antibodies targeting the receptor-binding domain•D614G shifts S protein conformation toward an ACE2-binding fusion-competent state
Structural and molecular insights into the SARS-CoV-2 spike protein variant D614G reveal the basis of its increased infectivity
Succinate functions both as a classical TCA cycle metabolite and an extracellular metabolic stress signal sensed by the mainly Gi-coupled succinate receptor SUCNR1. In the present study, we ...characterize and compare effects and signaling pathways activated by succinate and both classes of non-metabolite SUCNR1 agonists. By use of specific receptor and pathway inhibitors, rescue in G-protein-depleted cells and monitoring of receptor G protein activation by BRET, we identify Gq rather than Gi signaling to be responsible for SUCNR1-mediated effects on basic transcriptional regulation. Importantly, in primary human M2 macrophages, in which SUCNR1 is highly expressed, we demonstrate that physiological concentrations of extracellular succinate act through SUCNR1-activated Gq signaling to efficiently regulate transcription of immune function genes in a manner that hyperpolarizes their M2 versus M1 phenotype. Thus, sensing of stress-induced extracellular succinate by SUCNR1 is an important transcriptional regulator in human M2 macrophages through Gq signaling.
Key points
The purpose of this study was to determine the role of group III/IV muscle afferents in limiting the endurance exercise‐induced metabolic perturbation assayed in muscle biopsy samples ...taken from locomotor muscle.
Lumbar intrathecal fentanyl was used to attenuate the central projection of μ‐opioid receptor‐sensitive locomotor muscle afferents during a 5 km cycling time trial.
The findings suggest that the central projection of group III/IV muscle afferent feedback constrains voluntary neural ‘drive’ to working locomotor muscle and limits the exercise‐induced intramuscular metabolic perturbation.
Therefore, the CNS might regulate the degree of metabolic perturbation within locomotor muscle and thereby limit peripheral fatigue. It appears that the group III/IV muscle afferents are an important neural link in this regulatory mechanism, which probably serves to protect locomotor muscle from the potentially severe functional impairment as a consequence of severe intramuscular metabolic disturbance.
To investigate the role of metabo‐ and mechanosensitive group III/IV muscle afferents in limiting the intramuscular metabolic perturbation during whole body endurance exercise, eight subjects performed 5 km cycling time trials under control conditions (CTRL) and with lumbar intrathecal fentanyl impairing lower limb muscle afferent feedback (FENT). Vastus lateralis muscle biopsies were obtained before and immediately after exercise. Motoneuronal output was estimated through vastus lateralis surface electromyography (EMG). Exercise‐induced changes in intramuscular metabolites were determined using liquid and gas chromatography‐mass spectrometry. Quadriceps fatigue was quantified by pre‐ to post‐exercise changes in potentiated quadriceps twitch torque (ΔQTsingle) evoked by electrical femoral nerve stimulation. Although motoneuronal output was 21 ± 12% higher during FENT compared to CTRL (P < 0.05), time to complete the time trial was similar (∼8.8 min). Compared to CTRL, power output during FENT was 10 ± 4% higher in the first half of the time trial, but 11 ± 5% lower in the second half (both P < 0.01). The exercise‐induced increase in intramuscular inorganic phosphate, H+, adenosine diphosphate, lactate and phosphocreatine depletion was 55 ± 30, 62 ± 18, 129 ± 63, 47 ± 14 (P < 0.001) and 27 ± 14% (P < 0.01) greater in FENT than CTRL. ΔQTsingle was greater following FENT than CTRL (−52 ± 2 vs −31 ± 1%, P < 0.001) and this difference was positively correlated with the difference in inorganic phosphate (r2 = 0.79; P < 0.01) and H+ (r2 = 0.92; P < 0.01). In conclusion, during whole body exercise, group III/IV muscle afferents provide feedback to the CNS which, in turn, constrains motoneuronal output to the active skeletal muscle. This regulatory mechanism limits the exercise‐induced intramuscular metabolic perturbation, preventing an abnormal homeostatic challenge and excessive peripheral fatigue.
Key points
The purpose of this study was to determine the role of group III/IV muscle afferents in limiting the endurance exercise‐induced metabolic perturbation assayed in muscle biopsy samples taken from locomotor muscle.
Lumbar intrathecal fentanyl was used to attenuate the central projection of μ‐opioid receptor‐sensitive locomotor muscle afferents during a 5 km cycling time trial.
The findings suggest that the central projection of group III/IV muscle afferent feedback constrains voluntary neural ‘drive’ to working locomotor muscle and limits the exercise‐induced intramuscular metabolic perturbation.
Therefore, the CNS might regulate the degree of metabolic perturbation within locomotor muscle and thereby limit peripheral fatigue. It appears that the group III/IV muscle afferents are an important neural link in this regulatory mechanism, which probably serves to protect locomotor muscle from the potentially severe functional impairment as a consequence of severe intramuscular metabolic disturbance.
Detachment from the workforce following open heart valve surgery is a burden for the patient and society. The objectives were to examine patterns of employment status at different time points and to ...investigate factors associated with a lower likelihood of returning to the workforce within six months.
A cohort study of patients aged 18-63 undergoing valvular surgery at a Danish tertiary centre from 2013-2017. Return to the workforce was defined as being employed, unemployed (still capable of working) or receiving paid leave of absence. The association between demographic-, clinical characteristics (including a surgical risk evaluation, EuroScore), and return to the workforce were investigated with a multivariable logistic regression model.
In total, 1,395 consecutive patients underwent surgery, 347 were between 18 and 63 years and eligible for inclusion. Of those, 282 were attached to the workforce before surgery and included in the study. At the time of surgery, 79% were on paid sick leave. After six months, 21% of the patients (being part of the workforce before surgery), were still on sick leave. In the regression model, prolonged sick leave prior to surgery (OR 0.43, 95% CI 0.23-0.79) and EuroScore ≥ 2.3 (OR 0.39, 95% CI 0.21-0.74) significantly reduced the likelihood of returning to the workforce.
One-fifth of patients in the working-age were on sick leave six months after surgery. Prolonged sick leave prior to surgery and a EuroScore ≥2.3 were associated with a lower likelihood of returning to the workforce.
Sugar-sweetened beverage and caffeinated beverage consumption are associated with a variety of health issues among youth. Food and beverage marketing has been shown to affect youth's preferences, ...purchases, and consumption of marketed products. Previous research suggests that outdoor food and beverage marketing differs by community demographics, with more advertisements in lower-income communities and near schools. The purpose of this study is to examine the density of sugar-sweetened and caffeinated beverage advertisements near schools by school type (middle vs. high school) and by school-level SES.
Data are from the Outdoor Measuring and Evaluating the Determinants and Influence of Advertising (MEDIA)study, which documented and described all outdoor food and beverage advertisements near 47 middle and high schools in 2012. Beverage advertisements were categorized as: sugar-sweetened/caffeinated, sugar-sweetened/non-caffeinated, non-sugar-sweetened/caffeinated, or non-sugar-sweetened/non-caffeinated. Schools were categorized by type (middle vs high) and by SES as determined by the percentage of students qualifying for free or reduced-price lunch. Bootstrapped non-parametric Mann-Whitney U tests compared the number of advertisements in each category by school type and school-level SES (higher vs lower).
Compared to schools with higher SES, schools with lower SES had significantly more advertisements for sugar-sweetened/non-caffeinated beverages (Medianlow = 28.5 (IQR 17-69), vs Medianhigh = 10.5 (IQR 4-17) (p = 0.002)., sugar-sweetened non-caffeinated (Medianlow = 46 (IQR 16-99) vs Medianhigh = 13.5 (IQR 6-25), p = 0.002), -sugar-sweetened caffeinated (Medianlow = 12 (IQR 8-19) vs Medianhigh = 6 (IQR 2-8), p = 0.000), and non-sugar-sweetened non-caffeinated (Medianlow = 30 (IQR 13-65) vs Medianhigh = 14 (IQR 4-29), p = 0.045).There were no significant differences by school type.
This study adds to the literature demonstrating pervasive marketing of unhealthy products in lower-income communities. Disproportionate exposure to sugar-sweetened and caffeinated beverage advertisements in lower-income communities may contribute to the disparities in associated health outcomes by economic status.
Precision medicine, taking account of human individuality in genes, environment, and lifestyle for early disease diagnosis and individualized therapy, has shown great promise to transform medical ...care. Nontargeted metabolomics, with the ability to detect broad classes of biochemicals, can provide a comprehensive functional phenotype integrating clinical phenotypes with genetic and nongenetic factors. To test the application of metabolomics in individual diagnosis, we conducted a metabolomics analysis on plasma samples collected from 80 volunteers of normal health with complete medical records and three-generation pedigrees. Using a broad-spectrum metabolomics platform consisting of liquid chromatography and GC coupled with MS, we profiled nearly 600 metabolites covering 72 biochemical pathways in all major branches of biosynthesis, catabolism, gut microbiome activities, and xenobiotics. Statistical analysis revealed a considerable range of variation and potential metabolic abnormalities across the individuals in this cohort. Examination of the convergence of metabolomics profiles with whole-exon sequences (WESs) provided an effective approach to assess and interpret clinical significance of genetic mutations, as shown in a number of cases, including fructose intolerance, xanthinuria, and carnitine deficiency. Metabolic abnormalities consistent with early indications of diabetes, liver dysfunction, and disruption of gut microbiome homeostasis were identified in several volunteers. Additionally, diverse metabolic responses to medications among the volunteers may assist to identify therapeutic effects and sensitivity to toxicity. The results of this study demonstrate that metabolomics could be an effective approach to complement next generation sequencing (NGS) for disease risk analysis, disease monitoring, and drug management in our goal toward precision care.
Bacterial invasion of synovial joints, as in infectious or septic arthritis, can be difficult to treat in both veterinary and human clinical practice. Biofilms, in the form of free-floating clumps or ...aggregates, are involved with the pathogenesis of infectious arthritis and periprosthetic joint infection (PJI). Infection of a joint containing an orthopedic implant can additionally complicate these infections due to the presence of adherent biofilms. Because of these biofilm phenotypes, bacteria within these infected joints show increased antimicrobial tolerance even at high antibiotic concentrations. To date, animal models of PJI or infectious arthritis have been limited to small animals such as rodents or rabbits. Small animal models, however, yield limited quantities of synovial fluid making them impractical for in vitro research. Herein, we describe the use of ex vivo equine and porcine models for the study of synovial fluid induced biofilm aggregate formation and antimicrobial tolerance. We observed Staphylococcus aureus and other bacterial pathogens adapt the same biofilm aggregate phenotype with significant antimicrobial tolerance in both equine and porcine synovial fluid, analogous to human synovial fluid. We also demonstrate that enzymatic dispersal of synovial fluid aggregates restores the activity of antimicrobials. Future studies investigating the interaction of bacterial cell surface proteins with host synovial fluid proteins can be readily carried out in equine or porcine ex vivo models to identify novel drug targets for treatment of prevention of these difficult to treat infectious diseases.
Using the Zwicky Transient Facility alert stream, we are conducting a large spectroscopic campaign to construct a complete, volume-limited sample of transients brighter than 20 mag, and coincident ...within 100″ of galaxies in the Census of the Local Universe catalog. We describe the experiment design and spectroscopic completeness from the first 16 months of operations, which have classified 754 supernovae. We present results from a systematic search for calcium-rich gap transients in the sample of 22 low-luminosity (peak absolute magnitude M > −17), hydrogen-poor events found in the experiment. We report the detection of eight new events, and constrain their volumetric rate to 15% 5% of the SN Ia rate. Combining this sample with 10 previously known events, we find a likely continuum of spectroscopic properties ranging from events with SN Ia-like features (Ca-Ia objects) to those with SN Ib/c-like features (Ca-Ib/c objects) at peak light. Within the Ca-Ib/c events, we find two populations distinguished by their red (g − r 1.5 mag) or green ( mag) colors at the r-band peak, wherein redder events show strong line blanketing features and slower light curves (similar to Ca-Ia objects), weaker He lines, and lower Ca ii/O i in the nebular phase. We find that all together the spectroscopic continuum, volumetric rates, and striking old environments are consistent with the explosive burning of He shells on low-mass white dwarfs. We suggest that Ca-Ia and red Ca-Ib/c objects arise from the double detonation of He shells, while green Ca-Ib/c objects are consistent with low-efficiency burning scenarios like detonations in low-density shells or deflagrations.
Out-of-hospital cardiac arrest is a leading cause of death worldwide. Rapid diagnosis and initiation of cardiopulmonary resuscitation (CPR) is the cornerstone of therapy for victims of cardiac ...arrest. Yet a significant fraction of cardiac arrest victims have no chance of survival because they experience an unwitnessed event, often in the privacy of their own homes. An under-appreciated diagnostic element of cardiac arrest is the presence of agonal breathing, an audible biomarker and brainstem reflex that arises in the setting of severe hypoxia. Here, we demonstrate that a support vector machine (SVM) can classify agonal breathing instances in real-time within a bedroom environment. Using real-world labeled 9-1-1 audio of cardiac arrests, we train the SVM to accurately classify agonal breathing instances. We obtain an area under the curve (AUC) of 0.9993 ± 0.0003 and an operating point with an overall sensitivity and specificity of 97.24% (95% CI: 96.86-97.61%) and 99.51% (95% CI: 99.35-99.67%). We achieve a false positive rate between 0 and 0.14% over 82 h (117,985 audio segments) of polysomnographic sleep lab data that includes snoring, hypopnea, central, and obstructive sleep apnea events. We also evaluate our classifier in home sleep environments: the false positive rate was 0-0.22% over 164 h (236,666 audio segments) of sleep data collected across 35 different bedroom environments. We prototype our proof-of-concept contactless system using commodity smart devices (Amazon Echo and Apple iPhone) and demonstrate its effectiveness in identifying cardiac arrest-associated agonal breathing instances played over the air.
The effects of temporary mechanical circulatory support with a microaxial flow pump on mortality among patients with ST-segment elevation myocardial infarction (STEMI) complicated by cardiogenic ...shock remains unclear.
In an international, multicenter, randomized trial, we assigned patients with STEMI and cardiogenic shock to receive a microaxial flow pump (Impella CP) plus standard care or standard care alone. The primary end point was death from any cause at 180 days. A composite safety end point was severe bleeding, limb ischemia, hemolysis, device failure, or worsening aortic regurgitation.
A total of 360 patients underwent randomization, of whom 355 were included in the final analysis (179 in the microaxial-flow-pump group and 176 in the standard-care group). The median age of the patients was 67 years, and 79.2% were men. Death from any cause occurred in 82 of 179 patients (45.8%) in the microaxial-flow-pump group and in 103 of 176 patients (58.5%) in the standard-care group (hazard ratio, 0.74; 95% confidence interval CI, 0.55 to 0.99; P = 0.04). A composite safety end-point event occurred in 43 patients (24.0%) in the microaxial-flow-pump group and in 11 (6.2%) in the standard-care group (relative risk, 4.74; 95% CI, 2.36 to 9.55). Renal-replacement therapy was administered to 75 patients (41.9%) in the microaxial-flow-pump group and to 47 patients (26.7%) in the standard-care group (relative risk, 1.98; 95% CI, 1.27 to 3.09).
The routine use of a microaxial flow pump with standard care in the treatment of patients with STEMI-related cardiogenic shock led to a lower risk of death from any cause at 180 days than standard care alone. The incidence of a composite of adverse events was higher with the use of the microaxial flow pump. (Funded by the Danish Heart Foundation and Abiomed; DanGer Shock ClinicalTrials.gov number, NCT01633502.).
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