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1.
Nature ; 603(7900): 284-289, 2022 03.
Artigo em Inglês | MEDLINE | ID: mdl-35236981

RESUMO

Homo sapiens was present in northern Asia by around 40,000 years ago, having replaced archaic populations across Eurasia after episodes of earlier population expansions and interbreeding1-4. Cultural adaptations of the last Neanderthals, the Denisovans and the incoming populations of H. sapiens into Asia remain unknown1,5-7. Here we describe Xiamabei, a well-preserved, approximately 40,000-year-old archaeological site in northern China, which includes the earliest known ochre-processing feature in east Asia, a distinctive miniaturized lithic assemblage with bladelet-like tools bearing traces of hafting, and a bone tool. The cultural assembly of traits at Xiamabei is unique for Eastern Asia and does not correspond with those found at other archaeological site assemblages inhabited by archaic populations or those generally associated with the expansion of H. sapiens, such as the Initial Upper Palaeolithic8-10. The record of northern Asia supports a process of technological innovations and cultural diversification emerging in a period of hominin hybridization and admixture2,3,6,11.


Assuntos
Arqueologia , Hominidae , Comportamento de Utilização de Ferramentas , Animais , Osso e Ossos , China , História Antiga , Humanos , Homem de Neandertal
2.
Proc Natl Acad Sci U S A ; 118(34)2021 08 24.
Artigo em Inglês | MEDLINE | ID: mdl-34400505

RESUMO

The Early Cretaceous Jehol Biota is a terrestrial lagerstätte that contains exceptionally well-preserved fossils indicating the origin and early evolution of Mesozoic life, such as birds, dinosaurs, pterosaurs, mammals, insects, and flowering plants. New geochronologic studies have further constrained the ages of the fossil-bearing beds, and recent investigations on Early Cretaceous tectonic settings have provided much new information for understanding the spatiotemporal distribution of the biota and dispersal pattern of its members. Notably, the occurrence of the Jehol Biota coincides with the initial and peak stages of the North China craton destruction in the Early Cretaceous, and thus the biotic evolution is related to the North China craton destruction. However, it remains largely unknown how the tectonic activities impacted the development of the Jehol Biota in northeast China and other contemporaneous biotas in neighboring areas in East and Central Asia. It is proposed that the Early Cretaceous rift basins migrated eastward in the northern margin of the North China craton and the Great Xing'an Range, and the migration is regarded to have resulted from eastward retreat of the subducting paleo-Pacific plate. The diachronous development of the rift basins led to the lateral variations of stratigraphic sequences and depositional environments, which in turn influenced the spatiotemporal evolution of the Jehol Biota. This study represents an effort to explore the linkage between terrestrial biota evolution and regional tectonics and how plate tectonics constrained the evolution of a terrestrial biota through various surface geological processes.


Assuntos
Evolução Biológica , Biota , Dinossauros/fisiologia , Fósseis , Mamíferos/fisiologia , Análise Espaço-Temporal , Animais , Filogenia
3.
Proc Natl Acad Sci U S A ; 118(20)2021 05 18.
Artigo em Inglês | MEDLINE | ID: mdl-33972442

RESUMO

Localized regions of low geomagnetic intensity such as the South Atlantic Anomaly allow energetic particles from the Van Allen radiation belt to precipitate into the atmosphere and have been linked to a signature in the form of red aurora-like airglow visible to the naked eye. Smoothed global geomagnetic models predict a low-intensity West Pacific Anomaly (WPA) during the sixteenth to nineteenth centuries characterized by a simple time dependence. Here, we link the WPA to an independent database of equatorial aurorae recorded in Seoul, South Korea. These records show a complex fluctuating behavior in auroral frequency, whose overall trend from 1500 to 1800 AD is consistent with the locally weak geomagnetic field of the WPA, with a minimum at 1650 AD. We propose that the fluctuations in auroral frequency are caused by corresponding and hitherto unknown fluctuations in the regional magnetic intensity with peaks at 1590 and 1720 AD, a time dependence that has been masked by the smoothing inherent in regularized global geomagnetic models. A physical core flow model demonstrates that such behavior requires localized time-dependent upwelling flows in the Earth's core, possibly driven by regional lower-mantle anomalies.

4.
Proc Natl Acad Sci U S A ; 117(25): 14299-14305, 2020 06 23.
Artigo em Inglês | MEDLINE | ID: mdl-32513701

RESUMO

The Lower Cretaceous Huajiying Formation of the Sichakou Basin in northern Hebei Province, northern China contains key vertebrate taxa of the early Jehol Biota, e.g., Protopteryx fengningensis, Archaeornithura meemannae, Peipiaosteus fengningensis, and Eoconfuciusornis zhengi This formation arguably documents the second-oldest bird-bearing horizon, producing the oldest fossil records of the two major Mesozoic avian groups Enantiornithes and Ornithuromorpha. Hence, precisely determining the depositional ages of the Huajiying Formation would advance our understanding of the evolutionary history of the Jehol Biota. Here we present secondary ion mass spectrometry (SIMS) U-Pb zircon analysis results of eight interbedded tuff/tuffaceous sandstone samples from the Huajiying Formation. Our findings, combined with previous radiometric dates, suggest that the oldest enantiornithine and ornithuromorph birds in the Jehol Biota are ∼129-131 Ma, and that the Jehol Biota most likely first appeared at ∼135 Ma. This expands the biota's temporal distribution from late Valanginian to middle Aptian with a time span of about 15 My.


Assuntos
Biota , Aves/classificação , Chumbo/química , Silicatos/química , Zircônio/química , Animais , Evolução Biológica , China , Fósseis , Geologia , Filogenia , Espectrometria de Massa de Íon Secundário
5.
Proc Natl Acad Sci U S A ; 115(36): 8913-8918, 2018 09 04.
Artigo em Inglês | MEDLINE | ID: mdl-30126998

RESUMO

Polarity reversals of the geomagnetic field have occurred through billions of years of Earth history and were first revealed in the early 20th century. Almost a century later, details of transitional field behavior during geomagnetic reversals and excursions remain poorly known. Here, we present a multidecadally resolved geomagnetic excursion record from a radioisotopically dated Chinese stalagmite at 107-91 thousand years before present with age precision of several decades. The duration of geomagnetic directional oscillations ranged from several centuries at 106-103 thousand years before present to millennia at 98-92 thousand years before present, with one abrupt reversal transition occurring in one to two centuries when the field was weakest. These features indicate prolonged geodynamo instability. Repeated asymmetrical interhemispheric polarity drifts associated with weak dipole fields likely originated in Earth's deep interior. If such rapid polarity changes occurred in future, they could severely affect satellites and human society.

6.
Evol Anthropol ; 29(3): 125-142, 2020 May.
Artigo em Inglês | MEDLINE | ID: mdl-31859441

RESUMO

The Nihewan Basin of China preserves one of the most important successions of Paleolithic archeological sites in Eurasia. Stratified archeological sites and mammalian fossils, first reported in the 1920s, continue to be recovered in large-scale excavation projects. Here, we review key findings from archeological excavations in the Nihewan Basin ranging from ~1.66 Ma to 11.7 ka. We place particular emphasis on changes in stone tool technology over the long term. Though Pleistocene lithic industries from East Asia are often described as simple in character, re-evaluation of the stone tool evidence from the Nihewan Basin demonstrates significant, though periodic, innovations and variability in manufacturing techniques through time, indicating adaptive and technological flexibility on the part of hominins. Synthesis of paleoenvironmental and archeological data indicate changes in hominin occupation frequency in the Nihewan Basin, with chronological gaps suggesting that continuous presence in high, seasonal latitudes was not possible prior to the Late Pleistocene.


Assuntos
Arqueologia , Evolução Cultural , Hominidae/psicologia , Tecnologia , Animais , China , Humanos
7.
Proc Natl Acad Sci U S A ; 114(1): 39-44, 2017 01 03.
Artigo em Inglês | MEDLINE | ID: mdl-27980031

RESUMO

Variations of the Earth's geomagnetic field during the Holocene are important for understanding centennial to millennial-scale processes of the Earth's deep interior and have enormous potential implications for chronological correlations (e.g., comparisons between different sedimentary recording sequences, archaeomagnetic dating). Here, we present 21 robust archaeointensity data points from eastern China spanning the past ∼6 kyr. These results add significantly to the published data both regionally and globally. Taking together, we establish an archaeointensity reference curve for Eastern Asia, which can be used for archaeomagnetic dating in this region. Virtual axial dipole moments (VADMs) of the data range from a Holocene-wide low of ∼27 to "spike" values of ∼166 ZAm2 (Z: 1021). The results, in conjunction with our recently published data, confirm the existence of a decrease in paleointensity (DIP) in China around ∼2200 BCE. These low intensities are the lowest ever found for the Holocene and have not been reported outside of China. We also report a spike intensity of 165.8 ± 6.0 ZAm2 at ∼1300 BCE (±300 y), which is either a prelude to or the same event (within age uncertainties) as spikes first reported in the Levant.

8.
Proc Natl Acad Sci U S A ; 114(9): 2171-2176, 2017 02 28.
Artigo em Inglês | MEDLINE | ID: mdl-28193877

RESUMO

Microbes that synthesize minerals, a process known as microbial biomineralization, contributed substantially to the evolution of current planetary environments through numerous important geochemical processes. Despite its geological significance, the origin and evolution of microbial biomineralization remain poorly understood. Through combined metagenomic and phylogenetic analyses of deep-branching magnetotactic bacteria from the Nitrospirae phylum, and using a Bayesian molecular clock-dating method, we show here that the gene cluster responsible for biomineralization of magnetosomes, and the arrangement of magnetosome chain(s) within cells, both originated before or near the Archean divergence between the Nitrospirae and Proteobacteria This phylogenetic divergence occurred well before the Great Oxygenation Event. Magnetotaxis likely evolved due to environmental pressures conferring an evolutionary advantage to navigation via the geomagnetic field. Earth's dynamo must therefore have been sufficiently strong to sustain microbial magnetotaxis in the Archean, suggesting that magnetotaxis coevolved with the geodynamo over geological time.


Assuntos
Proteínas de Bactérias/genética , Evolução Biológica , Genoma Bacteriano , Magnetossomos/genética , Filogenia , Proteobactérias/genética , Teorema de Bayes , Expressão Gênica , Campos Magnéticos , Magnetossomos/química , Proteobactérias/classificação , Proteobactérias/metabolismo , Resposta Táctica
9.
Rapid Commun Mass Spectrom ; 33(6): 587-599, 2019 Mar 30.
Artigo em Inglês | MEDLINE | ID: mdl-30632217

RESUMO

RATIONALE: Issues induced by neutron irradiation makes 40 Ar/39 Ar dating inapplicable in some cases. The first issue is 37 Ar and 39 Ar recoil effects during irradiation that affect fine-grained minerals (<50 µm), such as lunar rocks, glassy groundmass, supergene minerals (e.g., illite, glauconite, Mg-oxide, etc.). The second issue from neutron irradiation is the high radioactivity gain of iron-rich samples such as pyrite, and the third is the production of interference nuclides during irradiation. The inherent drawbacks of conventional K-Ar and current unspiked K-Ar dating make it difficult to assess the reliability of age results. METHODS: A new approach is proposed using well-calibrated 40 Ar/39 Ar standard minerals to directly quantify 40 Ar, 38 Ar and 36 Ar. Fish Canyon sanidine (FCs), B4M muscovite and MMhb-1 hornblende, the widely used international standard minerals, were analyzed as unknowns to test the approach. Argon isotope analyses were carried out on a noble-gas mass spectrometer using laser fusion on microsamples (n × 0.01 to n × 0.2 mg). A new isochron - an "inverse isochron" for K-Ar dating - was designed. RESULTS: FCs and B4M yielded apparent and inverse isochron ages of 28.1 ± 0.1 and 28.0 ± 0.3 Ma, 18.2 ± 0.1 and 18.2 ± 0.5 Ma, which are consistent with the recommended ages, while the MMhb-1 presented lower apparent and inverse isochron ages (510.8 ± 4.8 and 512.3 ± 17.0 Ma) than the recommended ones. The initial argon compositions for the three standard minerals are 299.2 ± 205.3 (FCs), 294.0 ± 16.4 (B4M) and 290.9 ± 203.1 (MMhb-1), agreeing with that of air. CONCLUSIONS: The proposed approach potentially overcomes the issues of 40 Ar/39 Ar rising from irradiation and the drawbacks of K-Ar. By using laser fusion on multiple microaliquots from a same sample, this approach can produce accurate and precise K-Ar ages and give an inverse isochron. This new approach may provide an alternate dating method of geochronology based on argon isotopes.

11.
SLAS Technol ; : 100150, 2024 May 23.
Artigo em Inglês | MEDLINE | ID: mdl-38796033

RESUMO

This study aims to evaluate the changes in helper T lymphocyte (Th)1/Th2 factor levels in peripheral blood of patients with severe multiple injuries and their prognostic value for nosocomial infection using bioinformatic analysis. The experimental group consisted of 180 patients with numerous injuries admitted to our hospital between January 2021 and June 2023, with 80 healthy volunteers serving as controls. Th1 cytokines (interleukin-2 and interferon-γ) and Th2 cytokines (IL-4 and IL-10) were evaluated 48 hours after admission using enzyme-linked immunosorbent assays. The experimental group was separated into two groups: those with systemic inflammatory response syndrome (SIRS) and those without SIRS, for cytokine analysis and SIRS incidence. Furthermore, the study examined Th1 and Th2 cytokine levels in trauma patients in various body locations within the experimental group. A receiver operating characteristic (ROC) curve analysis was performed to determine the predictive value of Th1/Th2 cytokines for SIRS incidence. The experimental group had lower IL-2 and IFN-γ levels compared to the control group, but greater levels of IL-4 and IL-10. There were no significant variations in Th1 and Th2 cytokine levels across the experimental groups. Patients with SIRS had lower levels of IL-2 and IFN-γ but greater levels of IL-4 and IL-10 compared to those without SIRS. Combined cytokine levels have a better predictive value for SIRS than individual cytokines alone. In conclusion, individuals with severe multiple injuries had a change from Th1 to Th2 cytokine profiles, which was most evident in those with SIRS. The combined cytokine levels had a substantial predictive value for SIRS incidence in this patient cohort.

12.
Nat Commun ; 15(1): 2183, 2024 Mar 12.
Artigo em Inglês | MEDLINE | ID: mdl-38472217

RESUMO

The reorientation of Earth through rotation of its solid shell relative to its spin axis is known as True polar wander (TPW). It is well-documented at present, but the occurrence of TPW in the geologic past remains controversial. This is especially so for Late Jurassic TPW, where the veracity and dynamics of a particularly large shift remain debated. Here, we report three palaeomagnetic poles at 153, 147, and 141 million years (Myr) ago from the North China craton that document an ~ 12° southward shift in palaeolatitude from 155-147 Myr ago (~1.5° Myr-1), immediately followed by an ~ 10° northward displacement between 147-141 Myr ago (~1.6° Myr-1). Our data support a large round-trip TPW oscillation in the past 200 Myr and we suggest that the shifting back-and-forth of the continents may contribute to the biota evolution in East Asia and the global Jurassic-Cretaceous extinction and endemism.

13.
Natl Sci Rev ; 10(11): nwad251, 2023 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-37900194

RESUMO

Water input budget of global oceanic lithosphere at different tectonic settings are quantitatively estimated. The results indicate that the hydration at subduction zone is fundamentally essential to plate dynamics and water cycle of the Earth.

14.
Sci Bull (Beijing) ; 68(12): 1317-1326, 2023 06 30.
Artigo em Inglês | MEDLINE | ID: mdl-37268441

RESUMO

The Mesozoic terrestrial Jehol Biota of northern China exceeds the biomass and biodiversity of contemporaneous Lagerstätten. From 135 to 120 Ma, biotic radiation may have responded to the peak destruction of the North China Craton. However, the direct mechanistic link between geological and biological evolution is unclear. Phosphorus (P), a bio-essential nutrient, can be supplied by weathering of volcanics in terrestrial ecosystems. The middle-late Mesozoic volcanic-sedimentary sequences of northern China are amazingly rich in terrestrial organisms. Here we demonstrate episodic increases in P delivery, biological productivity, and species abundance in these strata to reveal the coevolution of volcanism and terrestrial biotas. A massive P supply from the weathering of voluminous volcanic products of craton destruction thus supported a terrestrial environment conducive to the high prosperity of the Jehol Biota. During the nascent stage of craton destruction, such volcanic-biotic coupling can also account for the preceding Yanliao Biota with relatively fewer fossils.


Assuntos
Ecossistema , Fósforo , Biota , Evolução Biológica , China
15.
World J Surg ; 36(10): 2428-35, 2012 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-22714574

RESUMO

OBJECTIVE: This study was designed to analyze the feasibility of classification for hepatic veins preoperatively and to evaluate the safety and therapeutic efficacy of precise hemihepatectomy guided by middle hepatic vein. METHODS: Thirty patients who underwent precise hemihepatectomy (PH group) were subjected to multi-slice helical CT hepatic venography preoperatively to achieve Nakamura's and Kawasaki's classification of hepatic veins. The hemihepatectomy was performed precisely by the guidance of middle hepatic vein, which was revealed by the hepatic venography and confirmed with intraoperative ultrasound. The clinical data of these patients were compared with other 38 traditional hemihepatectomy patients (control group). The amount of intraoperative bleeding and blood transfusion, liver function recovery, postoperative complications, and 1-year follow-up data were compared between two groups. RESULTS: The ratios of Nakamura's classification type I, II, and III of hepatic veins were 56.7 % (17/30), 26.7 % (8/30), and 16.7 % (5/30), respectively; The percentages of Kawasaki's classification type I and II of hepatic veins were 36.7 % (11/30) and 63.3 % (19/30), respectively. The total 30 cases of precise hemihepatectomies were performed successfully, including 13 cases of right hemihepatectomy without MHV, 15 cases of left hemihepatectomy without MHV, 1 case of right hemihepatectomy with MHV, and 1 case of left hemihepatectomy with MHV. There was no significant difference in operation-related mortality, the amount of intraoperative bleeding and blood transfusion, as well as serum alanine aminotransferase, total bilirubin, and cholinesterase of the third postoperative day between the two groups. However, negative resection margin and albumin level were more favorable in precise hemihepatectomy group than control group. In addition, the incidence of postoperative pleural effusion and seroperitoneum was decreased significantly in precise hemihepatectomy group. The 1-year, tumor-free survival rate was 79 % (15/19) In PH group, which is 48 % in control group. CONCLUSIONS: Preoperative evaluation of hepatic veins is of great value for individual operative program via determination of anatomical type of hepatic veins. Precise hemihepatectomy could preserve functional liver tissue with complete venous return to a great extent, resulting in fewer incidences of postoperative pleural effusion and seroperitoneum. Precise hemihepatectomy also has the potential to achieve more adequate tumor-free resection margin, which may result in higher tumor-free survival rate.


Assuntos
Hepatectomia/métodos , Veias Hepáticas/anatomia & histologia , Veias Hepáticas/diagnóstico por imagem , Tomografia Computadorizada Espiral , Adulto , Idoso , Estudos de Viabilidade , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Cuidados Pré-Operatórios
16.
Natl Sci Rev ; 9(1): nwab088, 2022 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-35070326

RESUMO

Cretaceous rift basin evolution was an important part of the tectonic history of northeast Asia in the late Mesozoic. Three types of rift basins are identified-active, passive and wide rift basins-and they developed in different regions. Passive rift basins in the eastern North China craton are thought to be the consequence of crustal stretching and passive asthenospheric upwelling. Wide rift basins in the eastern Central Asian orogen are assumed to originate from gravitational collapse of the thickened and heated orogenic crust. Active rift basins in the northern North China craton are attributed to uprising of asthenospheric materials along a lithospheric-scale tear fault. Slab tearing of the subducting paleo-Pacific plate is postulated and well explains the spatial distribution of different types of rift basins and the eastward shifting of magmatism in the northern North China craton. The Late Cretaceous witnessed a period of mild deformation and weak magmatism, which was possibly due to kinematic variation of the paleo-Pacific plate.

17.
Natl Sci Rev ; 8(1): nwaa053, 2021 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-34691547

RESUMO

The interplay between Pleistocene climatic variability and hominin adaptations to diverse terrestrial ecosystems is a key topic in human evolutionary studies. Early and Middle Pleistocene environmental change and its relation to hominin behavioural responses has been a subject of great interest in Africa and Europe, though little information is available for other key regions of the Old World, particularly from Eastern Asia. Here we examine key Early Pleistocene sites of the Nihewan Basin, in high-latitude northern China, dating between ∼1.4 and 1.0 million years ago (Ma). We compare stone-tool assemblages from three Early Pleistocene sites in the Nihewan Basin, including detailed assessment of stone-tool refitting sequences at the ∼1.1-Ma-old site of Cenjiawan. Increased toolmaking skills and technological innovations are evident in the Nihewan Basin at the onset of the Mid-Pleistocene Climate Transition (MPT). Examination of the lithic technology of the Nihewan sites, together with an assessment of other key Palaeolithic sites of China, indicates that toolkits show increasing diversity at the outset of the MPT and in its aftermath. The overall evidence indicates the adaptive flexibility of early hominins to ecosystem changes since the MPT, though regional abandonments are also apparent in high latitudes, likely owing to cold and oscillating environmental conditions. The view presented here sharply contrasts with traditional arguments that stone-tool technologies of China are homogeneous and continuous over the course of the Early Pleistocene.

18.
Natl Sci Rev ; 8(7): nwaa173, 2021 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-34691680

RESUMO

The India-Asia collision is an outstanding smoking gun in the study of continental collision dynamics. How and when the continental collision occurred remains a long-standing controversy. Here we present two new paleomagnetic data sets from rocks deposited on the distal part of the Indian passive margin, which indicate that the Tethyan Himalaya terrane was situated at a paleolatitude of ∼19.4°S at ∼75 Ma and moved rapidly northward to reach a paleolatitude of ∼13.7°N at ∼61 Ma. This implies that the Tethyan Himalaya terrane rifted from India after ∼75 Ma, generating the North India Sea. We document a new two-stage continental collision, first at ∼61 Ma between the Lhasa and Tethyan Himalaya terranes, and subsequently at ∼53-48 Ma between the Tethyan Himalaya terrane and India, diachronously closing the North India Sea from west to east. Our scenario matches the history of India-Asia convergence rates and reconciles multiple lines of geologic evidence for the collision.

19.
Biophys J ; 97(4): 986-91, 2009 Aug 19.
Artigo em Inglês | MEDLINE | ID: mdl-19686645

RESUMO

Magnetotactic bacteria are microorganisms that orient and migrate along magnetic field lines. The classical model of polar magnetotaxis predicts that the field-parallel migration velocity of magnetotactic bacteria increases monotonically with the strength of an applied magnetic field. We here test this model experimentally on magnetotactic coccoid bacteria that swim along helical trajectories. It turns out that the contribution of the field-parallel migration velocity decreases with increasing field strength from 0.1 to 1.5 mT. This unexpected observation can be explained and reproduced in a mathematical model under the assumption that the magnetosome chain is inclined with respect to the flagellar propulsion axis. The magnetic disadvantage, however, becomes apparent only in stronger than geomagnetic fields, which suggests that magnetotaxis is optimized under geomagnetic field conditions. It is therefore not beneficial for these bacteria to increase their intracellular magnetic dipole moment beyond the value needed to overcome Brownian motion in geomagnetic field conditions.


Assuntos
Fenômenos Fisiológicos Bacterianos/efeitos da radiação , Movimento Celular/fisiologia , Movimento Celular/efeitos da radiação , Modelos Biológicos , Simulação por Computador , Relação Dose-Resposta à Radiação , Campos Eletromagnéticos , Doses de Radiação
20.
Nanoscale ; 11(6): 2644-2654, 2019 Feb 07.
Artigo em Inglês | MEDLINE | ID: mdl-30575840

RESUMO

Iron oxide nanoparticles with good biocompatibility can serve as safe magnetic resonance imaging contrast agents. Herein, we report that ultrafine ferritin-based iron oxide (hematite/maghemite) nanoparticles synthesized by controlled biomimetic mineralization using genetically recombinant human H chain ferritin can be used as a positive contrast agent in magnetic resonance angiography. The synthesized magnetoferritin with an averaged core size of 2.2 ± 0.7 nm (hereafter named M-HFn-2.2) shows a r1 value of 0.86 mM-1 s-1 and a r2/r1 ratio of 25.1 at a 7 T magnetic field. Blood pool imaging on mice using the M-HFn-2.2 nanoparticles that were injected through a tail vein by single injection at a dose of 0.54 mM Fe per kg mouse body weight enabled detecting detailed vascular nets at 3 minutes post-injection; the MR signal intensity continuously enhanced up to 2 hours post-injection, which is much longer than that of the commercial magnevist (Gd-DTPA) contrast. Moreover, biodistribution examination indicates that organs such as liver, spleen and kidney safely cleared the injected nanoparticles within one day after the injection, demonstrating no risk of iron overload in test mice. Therefore, this study sheds light on developing high-performance gadolinium free positive magnetic resonance contrast agents for biomedical applications.


Assuntos
Meios de Contraste , Ferritinas , Angiografia por Ressonância Magnética/métodos , Nanopartículas de Magnetita/química , Animais , Encéfalo/irrigação sanguínea , Encéfalo/diagnóstico por imagem , Encéfalo/metabolismo , Meios de Contraste/química , Meios de Contraste/farmacocinética , Ferritinas/química , Ferritinas/farmacocinética , Humanos , Camundongos , Tamanho da Partícula , Distribuição Tecidual
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