Bacterial cell size is a multifactorial trait that is influenced by variables including nutritional availability and the timing of cell division. Prior work revealed a negative correlation between ...concentration of the alarmone (p)ppGpp (ppGpp) and cell length in
, suggesting that ppGpp may promote assembly of the division machinery (divisome) and cytokinesis in this organism. To clarify this counterintuitive connection between a starvation-induced stress response effector and cell proliferation, we undertook a systematic analysis of growth and division in
cells defective in ppGpp synthesis and/or engineered to overproduce the alarmone. Our data indicate that ppGpp acts indirectly on divisome assembly through its role as a global mediator of transcription. Loss of either ppGpp (ppGpp
) or the ppGpp-associated transcription factor DksA led to increased average length, with ppGpp
mutants also exhibiting a high frequency of extremely long filamentous cells. Using heat-sensitive division mutants and fluorescently labeled division proteins, we confirmed that ppGpp and DksA are cell division activators. We found that ppGpp and DksA regulate division through their effects on transcription, although the lack of known division genes or regulators in available transcriptomics data strongly suggests that this regulation is indirect. We also found that DksA inhibits division in ppGpp
cells, contrary to its role in a wild-type background. We propose that the ability of ppGpp to switch DksA from a division inhibitor to a division activator helps tune cell length across different concentrations of ppGpp. IMPORTANCE Cell division is a key step in the bacterial lifecycle that must be appropriately regulated to ensure survival. This work identifies the alarmone (p)ppGpp (ppGpp) as a general regulator of cell division, extending our understanding of the role of ppGpp beyond a signal for starvation and other stress. Even in nutrient-replete conditions, basal levels of ppGpp are essential for division to occur appropriately and for cell size to be maintained. This study establishes ppGpp as a "switch" that controls whether the transcription factor DksA behaves as a division activator or inhibitor. This unexpected finding enhances our understanding of the complex regulatory mechanisms employed by bacteria to coordinate division with diverse aspects of cell growth and stress response. Because division is an essential process, a better understanding of the mechanisms governing the assembly and activation of the division machinery could contribute to the development of novel therapeutics to treat bacterial infections.
Nature employs a limited number of genetically encoded axial ligands to control diverse heme enzyme activities. Deciphering the functional significance of these ligands requires a quantitative ...understanding of how their electron-donating capabilities modulate the structures and reactivities of the iconic ferryl intermediates compounds I and II. However, probing these relationships experimentally has proven to be challenging as ligand substitutions accessible via conventional mutagenesis do not allow fine tuning of electron donation and typically abolish catalytic function. Here, we exploit engineered translation components to replace the histidine ligand of cytochrome c peroxidase (CcP) by a less electron-donating N δ-methyl histidine (Me-His) with little effect on the enzyme structure. The rate of formation (k 1) and the reactivity (k 2) of compound I are unaffected by ligand substitution. In contrast, proton-coupled electron transfer to compound II (k 3) is 10-fold slower in CcP Me-His, providing a direct link between electron donation and compound II reactivity, which can be explained by weaker electron donation from the Me-His ligand (“the push”) affording an electron-deficient ferryl oxygen with reduced proton affinity (“the pull”). The deleterious effects of the Me-His ligand can be fully compensated by introducing a W51F mutation designed to increase “the pull” by removing a hydrogen bond to the ferryl oxygen. Analogous substitutions in ascorbate peroxidase lead to similar activity trends to those observed in CcP, suggesting that a common mechanistic strategy is employed by enzymes using distinct electron transfer pathways. Our study highlights how noncanonical active site substitutions can be used to directly probe and deconstruct highly evolved bioinorganic mechanisms.
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In 2016, a total of 18 human infections with influenza A(H3N2) virus occurred after exposure to influenza-infected swine at 7 agricultural fairs. Sixteen of these cases were the result of infection ...by a reassorted virus with increasing prevalence among US swine containing a hemagglutinin gene from 2010-11 human seasonal H3N2 strains.
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DOBA, IZUM, KILJ, NUK, ODKLJ, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
RATIONALE:Potential benefits of mesenchymal stem cell (MSC) therapy in heart failure may be related to paracrine properties and systemic effects, including anti-inflammatory activities. If this ...hypothesis is valid, intravenous administration of MSCs should improve outcomes in heart failure, an entity in which excessive chronic inflammation may play a pivotal role.
OBJECTIVE:To assess the safety and preliminary efficacy of intravenously administered ischemia-tolerant MSCs (itMSCs) in patients with nonischemic cardiomyopathy.
METHODS AND RESULTS:This was a single-blind, placebo-controlled, crossover, randomized phase II-a trial of nonischemic cardiomyopathy patients with left ventricular ejection fraction ≤40% and absent hyperenhancement on cardiac magnetic resonance imaging. Patients were randomized to intravenously administered itMSCs (1.5×10 cells/kg) or placebo; at 90 days, each group received the alternative treatment. Overall, 22 patients were randomized to itMSC (n=10) and placebo (n=12) at baseline. After crossover, data were available for 22 itMSC patients. No major differences in death, hospitalization, or serious adverse events were noted between the 2 treatments. Change from baseline in left ventricular ejection fraction and ventricular volumes was not significantly different between therapies. Compared with placebo, itMSC therapy increased 6-minute walk distance (+36.47 m, 95% confidence interval 5.98–66.97; P=0.02) and improved Kansas City Cardiomyopathy clinical summary (+5.22, 95% confidence interval 0.70–9.74; P=0.02) and functional status scores (+5.65, 95% confidence interval −0.11 to 11.41; P=0.06). The data demonstrated MSC-induced immunomodulatory effects, the magnitude of which correlated with improvement in left ventricular ejection fraction.
CONCLUSIONS:In this pilot study of patients with nonischemic cardiomyopathy, itMSC therapy was safe, caused immunomodulatory effects, and was associated with improvements in health status and functional capacity.
CLINICAL TRIAL REGISTRATION:URLhttp://www.clinicaltrials.gov. Unique identifierNCT02467387.
We quantify the contributions of different convection states to the magnetic flux throughput of the magnetosphere during 2010. To do this we provide a continuous classification of convection state ...for the duration of 2010 based upon observations of the solar wind and interplanetary magnetic field, geomagnetic indices, and field‐aligned currents measured by the Active Magnetosphere and Planetary Electrodynamics Response Experiment. Convection states are defined as (1) quiet, (2) weak activity, substorm (3) growth, (4) expansion and (5) recovery phases, (6) substorm driven phase (when relatively steady magnetospheric convection occurs), (7) recovery bays (when recovery phase is accompanied by a negative excursion of the AL electrojet index), and (8) periods of multiple intensifications (storm‐time periods when continuous short‐period AL activity occur). The magnetosphere is quiet for 46% of the time, when very little convection takes place. The majority of convection occurs during growth and driven phases (21% and 38%, respectively, of open magnetic flux accumulation by dayside reconnection). We discuss these results in the context of the expanding/contracting polar cap model of convection, and describe a framework within which isolated substorms and disturbances during periods of more continuous solar wind‐magnetosphere driving can be understood.
Plain Language Summary
Space weather within the Earth's geospace environment, including vivid auroral displays and geomagnetic activity that is damaging for satellites, telecommunications, global positioning systems, power distribution and pipelines, is caused by the interaction between the solar wind and the terrestrial magnetic field. We use observations of the solar wind, electric currents in the magnetosphere, and magnetic perturbations on the ground to analyze geomagnetic activity continuously for the whole of 2010. This allows us to determine that a range of responses are excited in the magnetosphere by different solar wind conditions, and to quantify the solar wind conditions that lead to most activity. These responses include substorms, geomagnetic storms, and periods of steady magnetospheric convection.
Key Points
We determine convection state and magnetic flux transport continuously for the duration of 2010
Our longitudinal study indicates that periods of balanced dayside/nightside reconnection play a major role in magnetic flux transport
Isolated substorms and those occurring during on‐going convection can be understood within the expanding‐contracting polar cap model
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BFBNIB, FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SAZU, SBCE, SBMB, UL, UM, UPUK
We present a cross-sectional study of ethical decision-making correlated with spirituality and utilizing moral intensity as a moderator for workers in the Southeastern United States (
N
= 117). This ...study presents spirituality as an individual variable and moral intensity as a situational variable along with ethical decision-making to examine the interaction of these factors in moral dilemmas. Utilizing previously validated instruments for ethical decision-making and individual spirituality, we find that workers with relatively high measured spirituality made less ethical decisions compared to workers with relatively lower measures of spirituality. Further, we find that the introduction of high moral intensity as a situational variable does not moderate the observed correlation between spirituality and ethical decision-making. This research supports the conceptual nature of the Interactionist Theory by presenting in a single study both individual and situational variables in ethical decision-making.
Gene panels for hereditary breast and ovarian cancer risk assessment are gaining acceptance, even though the clinical utility of these panels is not yet fully defined. Technical questions remain, ...however, about the performance and clinical interpretation of gene panels in comparison with traditional tests. We tested 1105 individuals using a 29-gene next-generation sequencing panel and observed 100% analytical concordance with traditional and reference data on >750 comparable variants. These 750 variants included technically challenging classes of sequence and copy number variation that together represent a significant fraction (13.4%) of the pathogenic variants observed. For BRCA1 and BRCA2 , we also compared variant interpretations in traditional reports to those produced using only non-proprietary resources and following criteria based on recent (2015) guidelines. We observed 99.8% net report concordance, albeit with a slightly higher variant of uncertain significance rate. In 4.5% of BRCA-negative cases, we uncovered pathogenic variants in other genes, which appear clinically relevant. Previously unseen variants requiring interpretation accumulated rapidly, even after 1000 individuals had been tested. We conclude that next-generation sequencing panel testing can provide results highly comparable to traditional testing and can uncover potentially actionable findings that may be otherwise missed. Challenges remain for the broad adoption of panel tests, some of which will be addressed by the accumulation of large public databases of annotated clinical variants.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
Optical tracking of collisions between insulating microbeads and an ultramicroelectrode surface are correlated to electrochemical measurements and 3D simulations. The experiments are based on partial ...blocking of the electrode surface by the beads. Results obtained using these three methods provide details regarding the radial distribution of landing locations, the extent of current blockage, collision frequency, motion of beads on the electrode surface following collisions, and aggregation behavior both prior to collisions and afterward on the electrode surface.
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9.
Cerebral protection strategies in aortic arch surgery: A network meta-analysis Hameed, Irbaz; Rahouma, Mohamed; Khan, Faiza M. ...
Journal of thoracic and cardiovascular surgery/The Journal of thoracic and cardiovascular surgery/The journal of thoracic and cardiovascular surgery,
January 2020, 2020-Jan, 2020-01-00, 20200101, Volume:
159, Issue:
1
Journal Article
Peer reviewed
Open access
Cerebral protection for aortic arch surgery has been widely studied, but comparisons of all the available strategies have rarely been performed. We performed direct and indirect comparisons of ...antegrade cerebral perfusion, retrograde cerebral perfusion, and deep hypothermic circulatory arrest in a network meta-analysis.
After a systematic literature search, studies comparing any combination of antegrade cerebral perfusion, retrograde cerebral perfusion, and deep hypothermic circulatory arrest were included, and a frequentist network meta-analysis was performed using the generic inverse variance method. The primary outcomes were postoperative stroke and operative mortality. Secondary outcomes were postoperative transient neurologic deficits, myocardial infarction, respiratory complications, and renal failure.
A total of 68 studies were included with a total of 26,968 patients. Compared with deep hypothermic circulatory arrest, both antegrade cerebral perfusion and retrograde cerebral perfusion were associated with significantly lower postoperative stroke and operative mortality rates: antegrade cerebral perfusion (odds ratio OR, 0.62; 95% confidence interval CI, 0.51-0.75; and OR, 0.63, 95% CI, 0.51-0.76, respectively) and retrograde cerebral perfusion (OR, 0.66; 95% CI, 0.54-0.82; and OR, 0.57; 95% CI, 0.45-0.71, respectively). Antegrade cerebral perfusion and retrograde cerebral perfusion were associated with similar incidence of primary outcomes. No difference among the 3 techniques was found in secondary outcomes. At meta-regression, circulatory arrest duration correlated with the neuroprotective effect of antegrade cerebral perfusion and retrograde cerebral perfusion compared with deep hypothermic circulatory arrest. Unilateral or bilateral antegrade cerebral perfusion and arrest temperature did not influence the results.
Antegrade cerebral perfusion and retrograde cerebral perfusion are associated with better postoperative outcomes compared with deep hypothermic circulatory arrest, and the relative benefit increases with the duration of the circulatory arrest. No differences between antegrade cerebral perfusion and retrograde cerebral perfusion were found for all the explored outcomes.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
The clinical diagnosis of new-onset type 1 diabetes has, for many years, been considered relatively straightforward. Recently, however, there is increasing awareness that within this single clinical ...phenotype exists considerable heterogeneity: disease onset spans the complete age range; genetic susceptibility is complex; rates of progression differ markedly, as does insulin secretory capacity; and complication rates, glycemic control, and therapeutic intervention efficacy vary widely. Mechanistic and immunopathological studies typically show considerable patchiness across subjects, undermining conclusions regarding disease pathways. Without better understanding, type 1 diabetes heterogeneity represents a major barrier both to deciphering pathogenesis and to the translational effort of designing, conducting, and interpreting clinical trials of disease-modifying agents. This realization comes during a period of unprecedented change in clinical medicine, with increasing emphasis on greater individualization and precision. For complex disorders such as type 1 diabetes, the option of maintaining the "single disease" approach appears untenable, as does the notion of individualizing each single patient's care, obliging us to conceptualize type 1 diabetes less in terms of phenotypes (observable characteristics) and more in terms of disease endotypes (underlying biological mechanisms). Here, we provide our view on an approach to dissect heterogeneity in type 1 diabetes. Using lessons from other diseases and the data gathered to date, we aim to delineate a roadmap through which the field can incorporate the endotype concept into laboratory and clinical practice. We predict that such an effort will accelerate the implementation of precision medicine and has the potential for impact on our approach to translational research, trial design, and clinical management.
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