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1.
J Med Virol ; 2020 Mar 12.
Artigo em Inglês | MEDLINE | ID: mdl-32162699

RESUMO

Coronavirus disease 2019 (COVID-19) caused by the severe acute respiratory syndrome coronavirus 2 has become an important public health issue in the world. More than 118 000 cases were confirmed around the world. The main clinical manifestations were respiratory symptoms and occasional gastrointestinal symptoms. However, there is no unified standard for the diagnosis and treatment of COVID-19. In the retrospective analysis, we report nine cases of COVID-19, describe the history of contact, clinical manifestations, the course of diagnosis and clinical treatment before, during and after treatment.

2.
Opt Express ; 27(23): 33027-33039, 2019 Nov 11.
Artigo em Inglês | MEDLINE | ID: mdl-31878377

RESUMO

An atomic magnetometer operated with elliptically polarized light is investigated theoretically and experimentally. To explore the potential of this magnetometric configuration, the analytical form of the outgoing signal is derived. Parameters that significantly influence the performance are optimized, which lead to a sensitivity of 300 fT/Hz at 45 ∘C with a 2×2×2 cm uncoated Rb vapor cell. It is remarkable that a sensitivity of 690 fT/Hz is achieved at room temperature of 24 ∘C, which is improved by an order of magnitude compared with the conventional Mx magnetometer under its own optimized condition. The elliptically polarized approach offers attractive features for developing compact, low-power magnetometers, which are available without heating the uncoated vapor cell.

3.
Opt Express ; 27(21): 29534-29546, 2019 Oct 14.
Artigo em Inglês | MEDLINE | ID: mdl-31684213

RESUMO

In a pulse pump Rb atomic magnetometer, the magnetic field is associated with the Larmor frequency of the free induction decay (FID) signal. The reconstruction of the magnetic field from the collected signal, thereby, is crucial for magnetocardiography. In this study, we propose a backward singular value decomposition (BSVD) method for fast reconstruction of a magnetocardiographic signal. Experiments on the simulated and real data were performed to estimate its potential advantages over previous approaches, such as the fast Fourier transform (FFT) method, the zero-crossing means (ZM) method, etc. The results show the high accuracy of the BSVD method compared with other methods. More importantly, the BSVD method requires less sampled data than other methods while ensuring the accuracy. With the help of it, the recording time can be greatly reduced from the initial 3.6m s to the present 0.6m s. Thus, the time resolution of the magnetocardiograph could reach 2m s which is equivalent to that of conventional electrocardiogragh. This will bring the atomic magnetocardiography more practicable in clinic application.

4.
Oncol Lett ; 17(5): 4237-4244, 2019 May.
Artigo em Inglês | MEDLINE | ID: mdl-30944618

RESUMO

The value of pharmacokinetic parameters derived from dynamic contrast-enhanced magnetic resonance imaging (DCE-MRI) in distinguishing pituitary microadenoma subtypes was investigated in the present study. Pathology and follow-up outcomes were applied as the gold standard for differentiating between 76 patients with pituitary microadenomas (38 prolactin-producing tumors, 17 adrenocorticotropic hormone adenomas and 21 growth hormone-producing tumors) and 20 patients with normal pituitary glands. DCE-MRI was conducted to obtain the following quantitative permeability parameters: Volume transfer constant (Ktrans), rate constant (Kep) and extracellular extravascular volume fraction (Ve). Among the 76 cases included, 61 were visually diagnosed using conventional MRI. The Ktrans, Kep and Ve of the microadenoma cases were 0.472±0.292/min, 0.765±0.359/min and 0.792±0.345, respectively. The Ktrans, Kep and Ve of the normal control group were 0.902±0.238/min, 1.208±0.599/min and 0.928±0.378, respectively. The Ktrans and Kep of patients with microadenomas were significantly lower compared with those of the normal controls (P<0.05). However, the Ve of the two groups did not significantly differ. Subtype differentiation analysis revealed that patients with growth hormone-producing tumors exhibited the highest Ktrans value (P<0.05). Kep significantly differed between growth hormone-producing tumors and the other two subtypes (P<0.05), but did not significantly differ among three subtypes. Receiver-operator characteristic analysis indicated that the area under the curve values of Ktrans and Kep were 0.884 and 0.728, respectively. Sensitivity and specificity were 95.0 and 82.6%, respectively, when Ktrans was set to 0.614/min as the cut-off value, and when the Kep cut-off value was set to 0.985/min, sensitivity and specificity were 60.0 and 81.3%, respectively. In conclusion, Ktrans and Kep derived from DCE-MRI could be applied to detect and identify microadenoma subtypes. Ktrans better reflects the blood perfusion alterations exhibited by patients with different microadenoma subtypes.

5.
Nucleic Acids Res ; 47(6): 3072-3085, 2019 04 08.
Artigo em Inglês | MEDLINE | ID: mdl-30952159

RESUMO

Alanyl-tRNA synthetases (AlaRSs) from three domains of life predominantly rely on a single wobble base pair, G3-U70, of tRNAAla as a major determinant. However, this base pair is divergent in human mitochondrial tRNAAla, but instead with a translocated G5-U68. How human mitochondrial AlaRS (hmtAlaRS) recognizes tRNAAla, in particular, in the acceptor stem region, remains unknown. In the present study, we found that hmtAlaRS is a monomer and recognizes mitochondrial tRNAAla in a G3-U70-independent manner, requiring several elements in the acceptor stem. In addition, we found that hmtAlaRS misactivates noncognate Gly and catalyzes strong transfer RNA (tRNA)-independent pre-transfer editing for Gly. A completely conserved residue outside of the editing active site, Arg663, likely functions as a tRNA translocation determinant to facilitate tRNA entry into the editing domain during editing. Finally, we investigated the effects of the severe infantile-onset cardiomyopathy-associated R592W mutation of hmtAlaRS on the canonical enzymatic activities of hmtAlaRS. Overall, our results provide fundamental information about tRNA recognition and deepen our understanding of translational quality control mechanisms by hmtAlaRS.


Assuntos
Conformação de Ácido Nucleico , RNA Mitocondrial/genética , RNA de Transferência de Alanina/genética , RNA de Transferência/genética , Alanina-tRNA Ligase/genética , Pareamento de Bases/genética , Domínio Catalítico , Escherichia coli/genética , Humanos , Cinética , Modelos Moleculares , Especificidade por Substrato
6.
Phys Rev Lett ; 120(23): 230504, 2018 Jun 08.
Artigo em Inglês | MEDLINE | ID: mdl-29932730

RESUMO

Quantum coherence is an invaluable physical resource for various quantum technologies. As a bona fide measure in quantifying coherence, the robustness of coherence (ROC) is not only mathematically rigorous, but also physically meaningful. We experimentally demonstrate the witness-observable and operational feature of the ROC in a multiqubit nuclear magnetic resonance system. We realize witness measurements by detecting the populations of quantum systems in one trial. The approach may also apply to physical systems compatible with ensemble or nondemolition measurements. Moreover, we experimentally show that the ROC quantifies the advantage enabled by a quantum state in a phase discrimination task.

7.
Nucleic Acids Res ; 46(9): 4662-4676, 2018 05 18.
Artigo em Inglês | MEDLINE | ID: mdl-29648639

RESUMO

Six pathogenic mutations have been reported in human mitochondrial tRNAThr (hmtRNAThr); however, the pathogenic molecular mechanism remains unclear. Previously, we established an activity assay system for human mitochondrial threonyl-tRNA synthetase (hmThrRS). In the present study, we surveyed the structural and enzymatic effects of pathogenic mutations in hmtRNAThr and then focused on m.15915 G > A (G30A) and m.15923A > G (A38G). The harmful evolutionary gain of non-Watson-Crick base pair A29/C41 caused hmtRNAThr to be highly susceptible to mutations disrupting the G30-C40 base pair in various ways; for example, structural integrity maintenance, modification and aminoacylation of tRNAThr, and editing mischarged tRNAThr. A similar phenomenon was observed for hmtRNATrp with an A29/C41 non-Watson-Crick base pair, but not in bovine mtRNAThr with a natural G29-C41 base pair. The A38G mutation caused a severe reduction in Thr-acceptance and editing of hmThrRS. Importantly, A38 is a nucleotide determinant for the t6A modification at A37, which is essential for the coding properties of hmtRNAThr. In summary, our results revealed the crucial role of the G30-C40 base pair in maintaining the proper structure and function of hmtRNAThr because of A29/C41 non-Watson-Crick base pair and explained the molecular outcome of pathogenic G30A and A38G mutations.


Assuntos
Mutação , RNA Mitocondrial/química , RNA de Transferência de Treonina/química , Anticódon , Pareamento de Bases , Humanos , Mitocôndrias/enzimologia , Edição de RNA , RNA Mitocondrial/genética , RNA Mitocondrial/metabolismo , RNA de Transferência de Treonina/genética , RNA de Transferência de Treonina/metabolismo , Treonina-tRNA Ligase/metabolismo , Aminoacilação de RNA de Transferência
8.
Zhonghua Yi Xue Za Zhi ; 95(23): 1837-41, 2015 Jun 16.
Artigo em Chinês | MEDLINE | ID: mdl-26712402

RESUMO

OBJECTIVE: To evaluate the diagnostic value of quantitative Dynamic Contrast Enhanced MRI analysis on pituitary adenoma. METHODS: With the standard of pathology and follow-up results, 67 cases of microadenoma, 20 cases of macroadenoma and 15 cases of normal pituitary were selected and taken routine scanning, meanwhile the dynamic contrast-enhanced scanning was performed, then the characteristics of lesions on conventional images were analyzed, and the mean permeability parameters were measured, including transfer rate (K(trans)), back flux rate (Kep), fractional EES volume (Ve) using Tofts model, which were compared with each other among those three groups and between prolactinoma and somatotroph adenoma; finally, the areas under the ROC curve of permeability parameters were compared. RESULTS: 61 cases of 67 cases of pituitary adenoma could be diagnosed by conventional methods, therefore the diagnostic accuracy was 91.1%. The K(trans), Kep and Ve values were(0.90 ± 0.23)/min, (1.14 ± 0.58)/min, 1.02 ± 0.51 respectively in normal pituitary, and (0.46 ± 0.23)/min, (0.80 ± 0.27)/min, 0.73 ± 0.32 in microadenoma and (0.41 ± 0.25)/min, (0.71 ± 0.48)/min, 0.66 ± 0.40 in macroadenoma. The K(trans) and Kep in normal adenoma were respectively higher than in microadenoma and macroadenoma, and the difference had statistical significance (P < 0.05), while the Ve value among these three groups had no statistical significance; the K(trans) in prolactinoma was higher than in somatotroph adenoma, and the difference had statistical significance(P < 0.05), while the difference of Kep and Ve between prolactinoma and somatotroph adenoma had no statistical significance. The area under the ROC curve in finding the microadenoma, K(trans), Kep were 0.915 and 0.738, and the sensitivity of K(trans) and Kep were 92.3% and 53.8%, and the specificity of K(trans) and Kep were 85% and 100%. CONCLUSION: Dynamic contrast-enhanced quantitative parameters, K(trans) and Kep are help to the diagnosis of pituitary adenoma, and K(trans) exhibits a relatively high diagnostic efficacy, and the value of diagnosis in K(trans) is higher than which in MRI conventional method; while K(trans) can differentiate certain secreting type of pituitary microadenoma.


Assuntos
Adenoma , Neoplasias Hipofisárias , Meios de Contraste , Humanos , Imagem por Ressonância Magnética , Prolactinoma , Curva ROC
9.
Phys Rev Lett ; 113(8): 080404, 2014 Aug 22.
Artigo em Inglês | MEDLINE | ID: mdl-25192080

RESUMO

Topological orders are exotic phases of matter existing in strongly correlated quantum systems, which are beyond the usual symmetry description and cannot be distinguished by local order parameters. Here we report an experimental quantum simulation of the Wen-plaquette spin model with different topological orders in a nuclear magnetic resonance system, and observe the adiabatic transition between two Z(2) topological orders through a spin-polarized phase by measuring the nonlocal closed-string (Wilson loop) operator. Moreover, we also measure the entanglement properties of the topological orders. This work confirms the adiabatic method for preparing topologically ordered states and provides an experimental tool for further studies of complex quantum systems.

10.
Phys Rev Lett ; 112(22): 220501, 2014 Jun 06.
Artigo em Inglês | MEDLINE | ID: mdl-24949746

RESUMO

Certain n-qubit quantum systems can be faithfully simulated by quantum circuits with only O(log(n)) qubits [B. Kraus, Phys. Rev. Lett. 107, 250503 (2011)]. Here we report an experimental realization of this compressed quantum simulation on a one-dimensional Ising chain. By utilizing an nuclear magnetic resonance quantum simulator with only five qubits, the property of ground-state magnetization of an open-boundary 32-spin Ising model is experimentally simulated, prefacing the expected quantum phase transition in the thermodynamic limit. This experimental protocol can be straightforwardly extended to systems with hundreds of spins by compressing them into up to merely 10-qubit systems. Our experiment paves the way for exploring physical phenomena in large-scale quantum systems with quantum simulators under current technology.

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