241 research outputs found
Effects of Black Pepper (Piper nigrum L.)
The chemical composition and antimicrobial mechanism of action of black pepper chloroform extract (BPCE) were investigated, as well as the potential antibacterial activities of BPCE against Escherichia coli and Staphylococcus aureus. The results showed that 1H-Cycloprop[e]azulen-7-ol, decahydro-1,1,7-trimethyl-4-methylene-, [1ar-(1aα,4aα,7β,7a,β,7bα.)]- (8.39%) and 2-methylene-4,8,8-trimethyl-4-vinyl-bicyclo[5.2.0]nonane (6.92%) were identified as the two primary components of BPCE. The release of intracellular transaminases from bacteria after being incubated with BPCE revealed that the bacterial cell walls and membranes were degraded and that protein synthesis was inhibited to some extent. The inhibition of bacterial Na+/K+-ATPase activity upon the addition of BPCE also indicated an enhanced permeability of bacterial cell membranes. Moreover, an analysis of hexokinase and pyruvate kinase activities showed that BPCE affected the metabolic rate of glycolysis and disrupted the normal metabolism of bacteria. This phenomenon was supported by an observed accumulation of lactic acid (LA) in the treated bacterial cells. Overall, our results indicated that BPCE damaged bacterial cell walls and membranes, which was followed by a disruption of bacterial cell respiration
Reprogramming of blood cells into induced pluripotent stem cells as a new cell source for cartilage repair
Characterization of hMSCs and hMSC-chondrogenic pellets. (a) Flow cytometric analysis of the hematopoietic markers (CD34, CD45) and MSC markers (CD73, CD105) in hMSCs. The proportion of CD73-expressing cells was 99.7 ± 0.63 %; The proportion of CD105-expressing cells was 98.7 ± 1.21 %. Values represent means ± SEM; n = 3. (b) Three-dimensional pellet culture of the hMSC-chondrogenic pellet. (c) Alcian blue staining and (d) toluidine blue staining of glycosaminoglycans and proteoglycans revealed the chondrocyte-type appearance in the hMSC-chondrogenic pellets. Scale bar = 100 μm. (e,f) Immunohistochemistry for type II and type X collagen. Scale bar = 100 μm. (TIF 8130 kb
Fly-by galaxy encounters with multiple black holes produce star-forming linear wakes
We look for simulated star-forming linear wakes such as the one recently
discovered by van Dokkum et al. (2023) in the cosmological hydrodynamical
simulation ASTRID. Amongst the runaway black holes in ASTRID, none are able to
produce clear star-forming wakes. Meanwhile, fly-by encounters, typically
involving a compact galaxy (with a central black hole) and a star-forming
galaxy (with a duo of black holes) reproduce remarkably well many of the key
properties (its length and linearity; recent star formation, etc.) of the
observed star-forming linear feature. We predict the feature to persist for
approximately 100 Myr in such a system and hence constitute a rare event. The
feature contains a partly stripped galaxy (with ) and a dual BH system () in
its brightest knot. X-ray emission from AGN in the knot should be detectable in
such systems. After from the first fly-by, the
galaxies merge leaving behind a triple black hole system in a (still) actively
star-forming early-type remnant of mass .
Follow-up JWST observations may be key for revealing the nature of these linear
features by potentially detecting the older stellar populations constituting
the bright knot. Confirmation of such detections may therefore help
discriminate a fly-by encounter from a massive BH wake to reveal the origin of
such features.Comment: 8 pages, 5 figures, comments welcom
Triple and Quadruple Black Holes in the ASTRID Simulation at
We use the ASTRID cosmological hydrodynamic simulation to investigate the
properties and evolution of triple and quadruple Massive Black Hole (MBH)
systems at . Only a handful of MBH tuple systems have been detected to
date. In ASTRID, we find of the are in tuples
with . The tuple systems span a range of
separations with the majority of the observable AGN systems at kpc. They include some of the most massive BHs (up to ) but with at least one of the components of . Tuples' host galaxies are typically massive with . We find that massive halos with host MBH tuples. Following the subsequent interactions between
MBHs in tuples, we found that in of the triplets all three MBHs
merge within a Gyr, and go through one merger. As a by-product of the
complex multi-galaxy interaction of these systems, we also find that up to
of tuples lead to runaway MBHs. In ASTRID, virtually all of the
ultramassive black holes () have undergone a triple quasar
phase while for BHs with this fraction drops
to .Comment: 10 pages, 9 figures; comments welcom
Orbital and Radiative Properties of Wandering Intermediate-Mass Black Holes in the ASTRID Simulation
Intermediate-Mass Black Holes (IMBHs) of are commonly
found at the center of dwarf galaxies. Simulations and observations
convincingly show that a sizable population of IMBHs could wander off-center in
galaxies. We use the cosmological simulation ASTRID to study the orbital and
radiative properties of wandering IMBHs in massive galaxies at . We
find that this population of black holes has large orbital inclinations
() with respect to the principal plane of the host. The
eccentricity of their orbits is also significant () and decreases
with time. Wandering IMBHs undergo spikes of accretion activity around the
pericenter of their orbits, with rates times the Eddington
rate and a median accretion duty cycle of . Their typical spectral
energy distribution peaks in the infrared at rest-frame.
Assuming a standard value of for the matter-to-energy radiative
efficiency, IMBHs reach keV X-ray luminosities for of the time. This luminosity corresponds
to fluxes within Mpc.
They could be challenging to detect because of competing emissions from X-ray
binaries and the interstellar medium. X-ray luminosities , in the hyper-luminous X-ray sources (HLXs) regime, are
reached by of the IMBHs. These findings suggest that HLXs are a
small subset of the wandering IMBH population, which is characterized by
luminosities times fainter. Dedicated surveys are needed to assess
the demographics of this missing population of black holes.Comment: Accepted for publication in MNRAS. This is the final version of the
manuscript. 9 pages, 7 figure
Bacterium-Enabled Transient Gene Activation by Artificial Transcription Factor for Resolving Gene Regulation in Maize
Cellular functions are diversified through intricate transcription regulations, and an understanding gene regulation networks is essential to elucidating many developmental processes and environmental responses. Here, we employed the Transcriptional-Activator Like effectors (TALes), which represent a family of transcription factors that are synthesized by members of the γ-proteobacterium genus Xanthomonas and secreted to host cells for activation of targeted host genes. Through delivery by the maize pathogen, Xanthomonas vasicola pv. vasculorum, designer TALes (dTALes), which are synthetic TALes, were used to induce the expression of the maize gene glossy3 (gl3), a MYB transcription factor gene involved in the cuticular wax biosynthesis. RNA-Seq analysis of leaf samples identified 146 gl3 downstream genes. Eight of the nine known genes known to be involved in the cuticular wax biosynthesis were up-regulated by at least one dTALe. A top-down Gaussian graphical model predicted that 68 gl3 downstream genes were directly regulated by GL3. A chemically induced mutant of the gene Zm00001d017418 from the gl3 downstream gene, encoding aldehyde dehydrogenase, exhibited a typical glossy leaf phenotype and reduced epicuticular waxes. The bacterial protein delivery of artificial transcription factors, dTALes, proved to be a straightforward and powerful approach for the revelation of gene regulation in plants
A vast population of wandering and merging IMBHs at cosmic noon
Massive black holes in the centers of galaxies today must have grown by
several orders of magnitude from seed black holes formed at early times.
Detecting a population of intermediate mass black holes (IMBHs) can provide
constraints on these elusive BH seeds. Here we use the large volume,
cosmological hydrodynamical simulation Astrid, which includes IMBH seeds and
dynamical friction to investigate the population of IMBH seeds. Dynamical
friction is largely inefficient at sinking and merging seed IMBHs at high-z.
This leads to an extensive population (several hundred per galaxy) of wandering
IMBHs in large halos at z~2. A small fraction of these IMBHs are detectable as
HLXs, Hyper Luminous X-ray sources. Importantly, at z ~ 2, IMBHs mergers
produce the peak of GW events. We find close to a million GW events in Astrid
between z=2-3 involving seed IMBH mergers. These GW events (almost all
detectable by LISA) at cosmic noon should provide strong constraints on IMBH
seed models and their formation mechanisms. At the center of massive galaxies,
where the number of IMBHs can be as high as 10-100, SMBH-IMBH pairs can form.
These Intermediate mass ratio inspirals (IMRIs) and extreme mass ratio
inspirals (EMRIs), will require the next generation of milli-muHz space-based
GW interferometers to be detected. Large populations of IMBHs around massive
black holes will probe their environments and MBH causal structure
Molecular imaging research in atherosclerosis: A 23-year scientometric and visual analysis
Background: Cardiovascular and cerebrovascular diseases are major global health problems, and the main cause is atherosclerosis. Recently, molecular imaging has been widely employed in the diagnosis and therapeutic applications of a variety of diseases, including atherosclerosis. Substantive facts have announced that molecular imaging has broad prospects in the early diagnosis and targeted treatment of atherosclerosis.Objective: We conducted a scientometric analysis of the scientific publications over the past 23 years on molecular imaging research in atherosclerosis, so as to identify the key progress, hotspots, and emerging trends.Methods: Original research and reviews regarding molecular imaging in atherosclerosis were retrieved from the Web of Science Core Collection database. Microsoft Excel 2021 was used to analyze the main findings. CiteSpace, VOSviewer, and a scientometric online platform were used to perform visualization analysis of the co-citation of journals and references, co-occurrence of keywords, and collaboration between countries/regions, institutions, and authors.Results: A total of 1755 publications were finally included, which were published by 795 authors in 443 institutions from 59 countries/regions. The United States was the top country in terms of the number and centrality of publications in this domain, with 810 papers and a centrality of 0.38, and Harvard University published the largest number of articles (182). Fayad, ZA was the most productive author, with 73 papers, while LIBBY P had the most co-citations (493). CIRCULATION was the top co-cited journal with a frequency of 1,411, followed by ARTERIOSCL THROM VAS (1,128). The co-citation references analysis identified eight clusters with a well-structured network (Q = 0.6439) and highly convincing clustering (S = 0.8865). All the studies calculated by keyword co-occurrence were divided into five clusters: “nanoparticle,” “magnetic resonance imaging,” “inflammation,” “positron emission tomography,” and “ultrasonography”. Hot topics mainly focused on cardiovascular disease, contrast media, macrophage, vulnerable plaque, and microbubbles. Sodium fluoride ⁃PET, targeted drug delivery, OCT, photoacoustic imaging, ROS, and oxidative stress were identified as the potential trends.Conclusion: Molecular imaging research in atherosclerosis has attracted extensive attention in academia, while the challenges of clinical transformation faced in this field have been described in this review. The findings of the present research can inform funding agencies and researchers toward future directions
COVID-19 vaccine-related misinformation identification among Chinese residents during a regional outbreak
ObjectivesMisinformation about the COVID vaccines poses a significant challenge to vaccination efforts in many countries. This study examined Chinese citizens’ ability to correctly identify COVID-19 vaccine misinformation in geographic areas with and without a regional outbreak. We also investigated the associations between misinformation identification and information source usage, source trust, perceived information quality, and demographic characteristics.SettingThe online survey was conducted in four cities from June 8th to 15th, 2021 in Guangdong Province, two of which were experiencing a regional surge of COVID-19 delta variant infections, and four cities in Hunan Province, a neighboring province largely unaffected.ParticipantsA total of 4,479 individuals aged 18 and above completed the online questionnaire. Given survey length, those who finished the study under 5 min were excluded, resulting in a final sample of 3,800.Outcome measurementsMisinformation identification, source exposure, source trust, and perceived information quality.ResultsResults showed slightly higher levels of correct misinformation identification in surge vs. non-surge areas. Trust in official information sources was positively associated with correct misinformation identification in full sample analysis, while trust in informal sources was negatively associated with the same outcome. Perceived information quality was positively associated with correct misinformation identification in the full sample.ConclusionInformation providers in China should enhance the quality of the vaccine information they provide, and the Chinese public should balance their usage of different sources of information to acquire vaccine knowledge
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