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1.
Nature ; 623(7989): 932-937, 2023 Nov.
Artículo en Inglés | MEDLINE | ID: mdl-38030780

RESUMEN

Planets with radii between that of the Earth and Neptune (hereafter referred to as 'sub-Neptunes') are found in close-in orbits around more than half of all Sun-like stars1,2. However, their composition, formation and evolution remain poorly understood3. The study of multiplanetary systems offers an opportunity to investigate the outcomes of planet formation and evolution while controlling for initial conditions and environment. Those in resonance (with their orbital periods related by a ratio of small integers) are particularly valuable because they imply a system architecture practically unchanged since its birth. Here we present the observations of six transiting planets around the bright nearby star HD 110067. We find that the planets follow a chain of resonant orbits. A dynamical study of the innermost planet triplet allowed the prediction and later confirmation of the orbits of the rest of the planets in the system. The six planets are found to be sub-Neptunes with radii ranging from 1.94R⊕ to 2.85R⊕. Three of the planets have measured masses, yielding low bulk densities that suggest the presence of large hydrogen-dominated atmospheres.

2.
Proc Natl Acad Sci U S A ; 120(49): e2306390120, 2023 Dec 05.
Artículo en Inglés | MEDLINE | ID: mdl-38015841

RESUMEN

Hepatitis B virus (HBV) remains a major public health threat with nearly 300 million people chronically infected worldwide who are at a high risk of developing hepatocellular carcinoma. Current therapies are effective in suppressing HBV replication but rarely lead to cure. Current therapies do not affect the HBV covalently closed circular DNA (cccDNA), which serves as the template for viral transcription and replication and is highly stable in infected cells to ensure viral persistence. In this study, we aim to identify and elucidate the functional role of cccDNA-associated host factors using affinity purification and protein mass spectrometry in HBV-infected cells. Nucleolin was identified as a key cccDNA-binding protein and shown to play an important role in HBV cccDNA transcription, likely via epigenetic regulation. Targeting nucleolin to silence cccDNA transcription in infected hepatocytes may be a promising therapeutic strategy for a functional cure of HBV.


Asunto(s)
Hepatitis B , Neoplasias Hepáticas , Humanos , Virus de la Hepatitis B/fisiología , Epigénesis Genética , Replicación Viral/genética , ADN Viral/metabolismo , ADN Circular/genética , ADN Circular/metabolismo , Neoplasias Hepáticas/genética , Hepatitis B/genética , Hepatitis B/metabolismo , Nucleolina
3.
Proc Natl Acad Sci U S A ; 119(48): e2209149119, 2022 11 29.
Artículo en Inglés | MEDLINE | ID: mdl-36413498

RESUMEN

Intravacuolar pathogens need to gradually expand their surrounding vacuole to accommodate the growing number of bacterial offspring during intracellular replication. Here we found that Legionella pneumophila controls vacuole expansion by fine-tuning the generation of lysophospholipids within the vacuolar membrane. Upon allosteric activation by binding to host ubiquitin, the type IVB (Dot/Icm) effector VpdC converts phospholipids into lysophospholipids which, at moderate concentrations, are known to promote membrane fusion but block it at elevated levels by generating excessive positive membrane curvature. Consequently, L. pneumophila overproducing VpdC were prevented from adequately expanding their surrounding membrane, trapping the replicating bacteria within spatially confined vacuoles and reducing their capability to proliferate intracellularly. Quantitative lipidomics confirmed a VpdC-dependent increase in several types of lysophospholipids during infection, and VpdC production in transiently transfected cells caused tubulation of organelle membranes as well as mitochondria fragmentation, processes that can be phenocopied by supplying cells with exogenous lysophospholipids. Together, these results demonstrate an important role for bacterial phospholipases in vacuolar expansion.


Asunto(s)
Legionella , Enfermedad de los Legionarios , Humanos , Legionella/metabolismo , Vacuolas/metabolismo , Enfermedad de los Legionarios/microbiología , Fosfolipasas/metabolismo , Ubiquitina/metabolismo , Proteínas Bacterianas/metabolismo , Lisofosfolípidos/metabolismo
4.
Glob Chang Biol ; 30(1): e16991, 2024 Jan.
Artículo en Inglés | MEDLINE | ID: mdl-37905464

RESUMEN

Sea turtles are vulnerable to climate change since their reproductive output is influenced by incubating temperatures, with warmer temperatures causing lower hatching success and increased feminization of embryos. Their ability to cope with projected increases in ambient temperatures will depend on their capacity to adapt to shifts in climatic regimes. Here, we assessed the extent to which phenological shifts could mitigate impacts from increases in ambient temperatures (from 1.5 to 3°C in air temperatures and from 1.4 to 2.3°C in sea surface temperatures by 2100 at our sites) on four species of sea turtles, under a "middle of the road" scenario (SSP2-4.5). Sand temperatures at sea turtle nesting sites are projected to increase from 0.58 to 4.17°C by 2100 and expected shifts in nesting of 26-43 days earlier will not be sufficient to maintain current incubation temperatures at 7 (29%) of our sites, hatching success rates at 10 (42%) of our sites, with current trends in hatchling sex ratio being able to be maintained at half of the sites. We also calculated the phenological shifts that would be required (both backward for an earlier shift in nesting and forward for a later shift) to keep up with present-day incubation temperatures, hatching success rates, and sex ratios. The required shifts backward in nesting for incubation temperatures ranged from -20 to -191 days, whereas the required shifts forward ranged from +54 to +180 days. However, for half of the sites, no matter the shift the median incubation temperature will always be warmer than the 75th percentile of current ranges. Given that phenological shifts will not be able to ameliorate predicted changes in temperature, hatching success and sex ratio at most sites, turtles may need to use other adaptive responses and/or there is the need to enhance sea turtle resilience to climate warming.


Asunto(s)
Tortugas , Animales , Tortugas/fisiología , Temperatura , Cambio Climático , Reproducción , Razón de Masculinidad
5.
Nature ; 557(7703): 68-70, 2018 05.
Artículo en Inglés | MEDLINE | ID: mdl-29720632

RESUMEN

Helium is the second-most abundant element in the Universe after hydrogen and is one of the main constituents of gas-giant planets in our Solar System. Early theoretical models predicted helium to be among the most readily detectable species in the atmospheres of exoplanets, especially in extended and escaping atmospheres 1 . Searches for helium, however, have hitherto been unsuccessful 2 . Here we report observations of helium on an exoplanet, at a confidence level of 4.5 standard deviations. We measured the near-infrared transmission spectrum of the warm gas giant 3 WASP-107b and identified the narrow absorption feature of excited metastable helium at 10,833 angstroms. The amplitude of the feature, in transit depth, is 0.049 ± 0.011 per cent in a bandpass of 98 angstroms, which is more than five times greater than what could be caused by nominal stellar chromospheric activity. This large absorption signal suggests that WASP-107b has an extended atmosphere that is eroding at a total rate of 1010 to 3 × 1011 grams per second (0.1-4 per cent of its total mass per billion years), and may have a comet-like tail of gas shaped by radiation pressure.

6.
Br J Sports Med ; 58(11): 598-605, 2024 May 28.
Artículo en Inglés | MEDLINE | ID: mdl-38621858

RESUMEN

OBJECTIVES: To evaluate the prevalence of abnormal ECG findings and their association with imaging results in male Brazilian football players. METHODS: The 'B-Pro Foot ECG' is a multicentre observational study conducted in 82 Brazilian professional clubs. It analysed 6125 players aged 15-35 years (2496 white, 2004 mixed-race and 1625 black individuals) who underwent cardiovascular screening from 2002 to 2023. All ECGs were reviewed by two experienced cardiologists in the athlete's care. Those with abnormal findings underwent further investigations, including a transthoracic echocardiogram (TTE). Cardiac magnetic resonance (CMR) was subsequently performed based on TTE findings or clinical suspicion. RESULTS: In total, 180 (3%) players had abnormal ECGs and 176 (98%) showed normal TTE results. Athletes aged 26-35 years had a higher prevalence of abnormal ECGs than younger athletes (15-25 years). Black players had a higher prevalence of T-wave inversion (TWI) in the inferior leads than white players (2.6% vs 1.4%; p=0.005), as well as in V5 (2.9%) and V6 (2.1%) compared with white (1.2% and 1.0%; p<0.001) and mixed-race (1.5% and 1.2%; p<0.05) players, respectively. TTE parameters were similar across ethnicities. However, four out of 75 players with inferolateral TWI showed abnormal TTEs and CMR findings consistent with cardiomyopathies. CMR also showed cardiomyopathies or myocarditis in four players with inferolateral TWI and normal TTEs. In total, nine (0.1%) athletes were diagnosed with cardiac diseases and were followed for 40±30 months, with no cardiac events documented. CONCLUSION: This study found a 3% prevalence of abnormal ECGs in male Brazilian football players. Inferolateral TWI was associated with cardiac pathologies confirmed by CMR, even in athletes with a normal TTE.


Asunto(s)
Ecocardiografía , Electrocardiografía , Fútbol , Humanos , Masculino , Brasil/epidemiología , Adolescente , Adulto Joven , Adulto , Prevalencia , Imagen por Resonancia Magnética
7.
Osteoarthritis Cartilage ; 31(3): 406-413, 2023 03.
Artículo en Inglés | MEDLINE | ID: mdl-36526151

RESUMEN

OBJECTIVE: Radiographic joint space width (JSW) has been a standard for measuring knee osteoarthritis (OA) structural change. Limitations in the responsiveness of this approach might be overcome by instead measuring 3D JSW on weight-bearing CT (WBCT). This study compared the responsiveness of 3D JSW measurements using WBCT with the responsiveness of radiographic 2D JSW. DESIGN: Standing, fixed-flexion knee radiographs (XR) and WBCT were acquired ancillary to the 144- and 168-month Multicenter Osteoarthritis Study visits. Tibiofemoral JSW was measured on both XR and WBCT. Responsiveness to change was defined by the standardized response mean (SRM) for change in JSW (1) at predetermined mediolateral locations (JSWx) on both modalities and (2) in the following subregions measured on WBCT images: central medial and lateral femur (CMF/CLF) and tibia (CMT/CLT), and anterior and posterior tibia (AMT/ALT, PMT/MLT). RESULTS: Baseline and 24-month follow-up JSWx measurements were completed for 265 participants (58.1% women). Responsiveness of 3D JSWx for medial tibiofemoral compartment on coronal WBCT (SRM range: -0.18, -0.24) exceeded that for 2D JSWx (-0.10, -0.16). Responsiveness of 3D JSW subregional mean (-0.06, -0.36) and maximal (-1.14, -1.75) CMF and CMT and maximal CLF/CLT 3D JSW changes were statistically significantly greater in comparison with respective medial and lateral 2D JSWx (P ≤ 0.002). CONCLUSIONS: Subregional 3D JSW on WBCT is substantially more responsive to 24-month changes in tibiofemoral joint structure compared to radiographic measurements. Use of subregional 3D JSW on WBCT could enable improved detection of OA structural progression over a 24-month duration in comparison with measurements made on XR.


Asunto(s)
Articulación de la Rodilla , Osteoartritis de la Rodilla , Humanos , Femenino , Masculino , Radiografía , Osteoartritis de la Rodilla/diagnóstico por imagen , Tibia , Tomografía Computarizada por Rayos X
8.
Phys Rev Lett ; 130(24): 242301, 2023 Jun 16.
Artículo en Inglés | MEDLINE | ID: mdl-37390421

RESUMEN

The elliptic (v_{2}) and triangular (v_{3}) azimuthal anisotropy coefficients in central ^{3}He+Au, d+Au, and p+Au collisions at sqrt[s_{NN}]=200 GeV are measured as a function of transverse momentum (p_{T}) at midrapidity (|η|<0.9), via the azimuthal angular correlation between two particles both at |η|<0.9. While the v_{2}(p_{T}) values depend on the colliding systems, the v_{3}(p_{T}) values are system independent within the uncertainties, suggesting an influence on eccentricity from subnucleonic fluctuations in these small-sized systems. These results also provide stringent constraints for the hydrodynamic modeling of these systems.


Asunto(s)
Hidrodinámica , Masculino , Humanos , Anisotropía , Movimiento (Física)
10.
Phys Rev Lett ; 130(21): 212301, 2023 May 26.
Artículo en Inglés | MEDLINE | ID: mdl-37295104

RESUMEN

We report here the first observation of directed flow (v_{1}) of the hypernuclei _{Λ}^{3}H and _{Λ}^{4}H in mid-central Au+Au collisions at sqrt[s_{NN}]=3 GeV at RHIC. These data are taken as part of the beam energy scan program carried out by the STAR experiment. From 165×10^{6} events in 5%-40% centrality, about 8400 _{Λ}^{3}H and 5200 _{Λ}^{4}H candidates are reconstructed through two- and three-body decay channels. We observe that these hypernuclei exhibit significant directed flow. Comparing to that of light nuclei, it is found that the midrapidity v_{1} slopes of _{Λ}^{3}H and _{Λ}^{4}H follow baryon number scaling, implying that the coalescence is the dominant mechanism for these hypernuclei production in the 3 GeV Au+Au collisions.

11.
Phys Rev Lett ; 130(11): 112301, 2023 Mar 17.
Artículo en Inglés | MEDLINE | ID: mdl-37001106

RESUMEN

We report on measurements of sequential ϒ suppression in Au+Au collisions at sqrt[s_{NN}]=200 GeV with the STAR detector at the Relativistic Heavy Ion Collider (RHIC) through both the dielectron and dimuon decay channels. In the 0%-60% centrality class, the nuclear modification factors (R_{AA}), which quantify the level of yield suppression in heavy-ion collisions compared to p+p collisions, for ϒ(1S) and ϒ(2S) are 0.40±0.03(stat)±0.03(sys)±0.09(norm) and 0.26±0.08(stat)±0.02(sys)±0.06(norm), respectively, while the upper limit of the ϒ(3S) R_{AA} is 0.17 at a 95% confidence level. This provides experimental evidence that the ϒ(3S) is significantly more suppressed than the ϒ(1S) at RHIC. The level of suppression for ϒ(1S) is comparable to that observed at the much higher collision energy at the Large Hadron Collider. These results point to the creation of a medium at RHIC whose temperature is sufficiently high to strongly suppress excited ϒ states.

12.
Phys Rev Lett ; 130(8): 082301, 2023 Feb 24.
Artículo en Inglés | MEDLINE | ID: mdl-36898098

RESUMEN

We report the beam energy and collision centrality dependence of fifth and sixth order cumulants (C_{5}, C_{6}) and factorial cumulants (κ_{5}, κ_{6}) of net-proton and proton number distributions, from center-of-mass energy (sqrt[s_{NN}]) 3 GeV to 200 GeV Au+Au collisions at RHIC. Cumulant ratios of net-proton (taken as proxy for net-baryon) distributions generally follow the hierarchy expected from QCD thermodynamics, except for the case of collisions at 3 GeV. The measured values of C_{6}/C_{2} for 0%-40% centrality collisions show progressively negative trend with decreasing energy, while it is positive for the lowest energy studied. These observed negative signs are consistent with QCD calculations (for baryon chemical potential, µ_{B}≤110 MeV) which contains the crossover transition range. In addition, for energies above 7.7 GeV, the measured proton κ_{n}, within uncertainties, does not support the two-component (Poisson+binomial) shape of proton number distributions that would be expected from a first-order phase transition. Taken in combination, the hyperorder proton number fluctuations suggest that the structure of QCD matter at high baryon density, µ_{B}∼750 MeV at sqrt[s_{NN}]=3 GeV is starkly different from those at vanishing µ_{B}∼24 MeV at sqrt[s_{NN}]=200 GeV and higher collision energies.

13.
Phys Rev Lett ; 131(20): 202301, 2023 Nov 17.
Artículo en Inglés | MEDLINE | ID: mdl-38039468

RESUMEN

The polarization of Λ and Λ[over ¯] hyperons along the beam direction has been measured relative to the second and third harmonic event planes in isobar Ru+Ru and Zr+Zr collisions at sqrt[s_{NN}]=200 GeV. This is the first experimental evidence of the hyperon polarization by the triangular flow originating from the initial density fluctuations. The amplitudes of the sine modulation for the second and third harmonic results are comparable in magnitude, increase from central to peripheral collisions, and show a mild p_{T} dependence. The azimuthal angle dependence of the polarization follows the vorticity pattern expected due to elliptic and triangular anisotropic flow, and qualitatively disagrees with most hydrodynamic model calculations based on thermal vorticity and shear induced contributions. The model results based on one of existing implementations of the shear contribution lead to a correct azimuthal angle dependence, but predict centrality and p_{T} dependence that still disagree with experimental measurements. Thus, our results provide stringent constraints on the thermal vorticity and shear-induced contributions to hyperon polarization. Comparison to previous measurements at RHIC and the LHC for the second-order harmonic results shows little dependence on the collision system size and collision energy.

14.
Phys Rev Lett ; 130(20): 202301, 2023 May 19.
Artículo en Inglés | MEDLINE | ID: mdl-37267557

RESUMEN

We report the triton (t) production in midrapidity (|y|<0.5) Au+Au collisions at sqrt[s_{NN}]=7.7-200 GeV measured by the STAR experiment from the first phase of the beam energy scan at the Relativistic Heavy Ion Collider. The nuclear compound yield ratio (N_{t}×N_{p}/N_{d}^{2}), which is predicted to be sensitive to the fluctuation of local neutron density, is observed to decrease monotonically with increasing charged-particle multiplicity (dN_{ch}/dη) and follows a scaling behavior. The dN_{ch}/dη dependence of the yield ratio is compared to calculations from coalescence and thermal models. Enhancements in the yield ratios relative to the coalescence baseline are observed in the 0%-10% most central collisions at 19.6 and 27 GeV, with a significance of 2.3σ and 3.4σ, respectively, giving a combined significance of 4.1σ. The enhancements are not observed in peripheral collisions or model calculations without critical fluctuation, and decreases with a smaller p_{T} acceptance. The physics implications of these results on the QCD phase structure and the production mechanism of light nuclei in heavy-ion collisions are discussed.

15.
J Endovasc Ther ; : 15266028231157639, 2023 Mar 10.
Artículo en Inglés | MEDLINE | ID: mdl-36896884

RESUMEN

PURPOSE: To gain insight into safety and efficacy of in situ and ex-situ fenestration techniques for total endovascular arch repair. The term ex-situ fenestration is referring to physician-modified stent-graft technique where fenestration is performed on a back table. METHODS: Electronic search was conducted according to PRISMA (Preferred Reporting Items for Systematic review and Meta-analyses) guidelines from 2000 to 2020. The main outcomes measured were 30-day mortality, stroke, aortic-related mortality, and reintervention rates. RESULTS: Fifteen studies were eligible: 7 ex-situ fenestration (189 patients) and 8 in-situ fenestration (149 patients). In ex-situ group, dissection was the main pathology treated and proximal sealing zones were Z0 or 1 in 53.5% of patients. In in-situ group, dissection and aneurysm were equally represented in around 40% of cases and proximal sealing zones were Z0 or 1 in 46.5% of patients. Cumulative 30-day all-cause mortality was similar in both groups: 3.8% (95% confidence interval [CI]: 1.7%-8.2%) and 3.8% (95% CI: 1.6%-8.9%), respectively, in ex-situ and in-situ groups and stroke rate of 2.8% (95% CI: 1.1%-7%) and 5.3% (95% CI: 2.6%-10.5%). After a 11.1 ± 2.6 months mean follow-up for ex-situ and 16.7 ± 2.3 months for in-situ group, there were 5.2 and 1.4 reinterventions per 100 patients-years, respectively, for ex-situ and in situ groups. Aortic-related mortality rates of, respectively, 3.2% (95% CI: 1.3%-7.4%) and 2.6% (95% CI: 0.9%-7.3%) were noted in ex-situ and in situ groups. CONCLUSION: The reported data show favorable short-term results of both ex-situ and in-situ fenestration techniques with low mortality and strokes rates. However, durability is still questionable given the lack of long-term data. Both options may have their place in arch repair beyond the spectrum of emergent and urgent cases, on condition that results stand the test of time. CLINICAL IMPACT: In situ and ex-situ fenestration techniques have been initially developed to overcome emergency or as a bail out techniques however giving the promessing favorable short term results indications of these techniques may be extended to elective patients ineligible to customized stent-grafts and possibly in the futur to more elective cases as an option for total endovascular arch repair.

16.
J Chem Phys ; 159(13)2023 Oct 07.
Artículo en Inglés | MEDLINE | ID: mdl-37787128

RESUMEN

We present a theory for pitch, a matrix property that is linked to the coupling of rotational and translational motion of rigid bodies at low Reynolds numbers. The pitch matrix is a geometric property of objects in contact with a surrounding fluid, and it can be decomposed into three principal axes of pitch and their associated moments of pitch. The moments of pitch predict the translational motion in a direction parallel to each pitch axis when the object is rotated around that axis and can be used to explain translational drift, particularly for rotating helices. We also provide a symmetrized boundary element model for blocks of the resistance tensor, allowing calculation of the pitch matrix for arbitrary rigid bodies. We analyze a range of chiral objects, including chiral molecules and helices. Chiral objects with a Cn symmetry axis with n > 2 show additional symmetries in their pitch matrices. We also show that some achiral objects have non-vanishing pitch matrices, and we use this result to explain recent observations of achiral microswimmers. We also discuss the small but non-zero pitch of Lord Kelvin's isotropic helicoid.

17.
Inj Prev ; 29(4): 320-326, 2023 08.
Artículo en Inglés | MEDLINE | ID: mdl-36918272

RESUMEN

INTRODUCTION: In 2018, the American Academy of Pediatrics updated their car safety seat (CSS) guidelines to recommend that children ride rear-facing as long as possible, yet evidence from observational studies on rear-facing CSS effectiveness is limited. This study estimated the association between rear-facing CSS use and injuries among children aged 0-4 years who were involved in motor vehicle crashes (MVCs). METHODS: This study analysed data on all MVCs involving children aged 0-4 years reported to the Kansas Department of Transportation from 2011 to 2020. Children who were in a rear-facing CSS were compared with children who rode in a forward-facing device. Logistic regression was used to adjust for potential confounders. RESULTS: In unadjusted models, rear-facing CSS use was associated with a 14% reduction in the odds of suffering any injury versus riding in a forward-facing CSS (OR 0.860, 95% CI 0.805 to 0.919). In models adjusted for potential confounders, rear-facing CSS use was associated with a 9% reduction in the odds of any injury relative to riding forward-facing (OR 0.909, 95% CI 0.840 to 0.983). These estimates were driven by children seated in the back outboard positions. Rear-facing CSS use was also negatively associated with incapacitating/fatal injuries, but these estimates were imprecise. CONCLUSIONS: Children aged 0-4 years are less likely to be injured in an MVC if they are restrained in a rear-as opposed to forward-facing CSS. These results are particularly relevant because a number of state CSS laws do not require children of any age to ride rear-facing.


Asunto(s)
Sistemas de Retención Infantil , Equipo Infantil , Heridas y Lesiones , Niño , Humanos , Estados Unidos , Accidentes de Tránsito/prevención & control , Modelos Logísticos , Vehículos a Motor , Heridas y Lesiones/epidemiología , Heridas y Lesiones/prevención & control
18.
An Acad Bras Cienc ; 95(1): e20220205, 2023.
Artículo en Inglés | MEDLINE | ID: mdl-36946810

RESUMEN

Haemulidae represents one of the most diverse, widespread and conspicuous families of Perciformes, in which most species are marine, some brackish and rarely from freshwater. From April 2009 to July 2012, 120 specimens of Conodon nobilis, 60 Orthopristis rubra and 50 Anisotremus virginicus were collected off the State of Rio de Janeiro, Brazil, and analyzed for metazoan parasites. A total of 16 parasite taxa were found on/in A. virginicus, 19 on/in Co. nobilis and 21 on/in O. rubra, in which ectoparasites were most common on A. virginicus and Co. nobilis and endoparasites in O. rubra. All parasites showed aggregate pattern of distribution (discrepancy index values higher than 0.70). Mean abundance, species richness and Brillouin index (diversity) differed among the host species, i.e., O. rubra showed the highest values, followed by A. virginicus and Co. nobilis with intermediate and lowest values, respectively. At infracommunity level was possible to observe high similarity of parasite composition among the three host species. The digeneans Leurodera decora and Monorchis latus, and the acanthocephalan Koronacantha sp. represent new locality records off Brazil. Moreover, five, four and two taxa are reported, for the first time, parasitizing Co. nobilis, A. virginicus and O. rubra, respectively.


Asunto(s)
Enfermedades de los Peces , Parásitos , Perciformes , Animales , Brasil , Peces/parasitología , Perciformes/parasitología , Océano Atlántico
19.
Mol Microbiol ; 115(2): 290-304, 2021 02.
Artículo en Inglés | MEDLINE | ID: mdl-32996200

RESUMEN

Bacteroides fragilis toxin (BFT) is a protein secreted by enterotoxigenic (ETBF) strains of B. fragilis. BFT is synthesized as a proprotein (proBFT) that is predicted to be a lipoprotein and that is cleaved into two discrete fragments by a clostripain-like protease called fragipain (Fpn). In this study, we obtained evidence that Fpn cleaves proBFT following its transport across the outer membrane. Remarkably, we also found that the disruption of the fpn gene led to a strong reduction in the level of >100 other proteins, many of which are predicted to be lipoproteins, in the culture medium of an ETBF strain. Experiments performed with purified Fpn provided direct evidence that the protease releases at least some of these proteins from the cell surface. The observation that wild-type cells outcompeted an fpn- strain in co-cultivation assays also supported the notion that Fpn plays an important role in cell physiology and is not simply dedicated to toxin biogenesis. Finally, we found that purified Fpn altered the adhesive properties of HT29 intestinal epithelial cells. Our results suggest that Fpn is a broad-spectrum protease that not only catalyzes the protein secretion on a wide scale but that also potentially cleaves host cell proteins during colonization.


Asunto(s)
Toxinas Bacterianas/metabolismo , Bacteroides fragilis/metabolismo , Metaloendopeptidasas/metabolismo , Péptido Hidrolasas/metabolismo , Bacteroides fragilis/genética , Cisteína Endopeptidasas/metabolismo , Lipoproteínas/metabolismo , Péptido Hidrolasas/fisiología
20.
Small ; 18(28): e2201816, 2022 07.
Artículo en Inglés | MEDLINE | ID: mdl-35638191

RESUMEN

Measuring vibrations is essential to ensuring building structural safety and machine stability. Predictive maintenance is a central internet of things (IoT) application within the new industrial revolution, where sustainability and performance increase over time are going to be paramount. To reduce the footprint and cost of vibration sensors while improving their performance, new sensor concepts are needed. Here, double-layer graphene membranes are utilized with a suspended silicon proof demonstrating their operation as resonant vibration sensors that show outstanding performance for a given footprint and proof mass. The unveiled sensing effect is based on resonant transduction and has important implications for experimental studies involving thin nano and micro mechanical resonators that are excited by an external shaker.


Asunto(s)
Grafito , Sistemas Microelectromecánicos , Diseño de Equipo , Grafito/química , Silicio , Vibración
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