Your browser doesn't support javascript.
loading
Mostrar: 20 | 50 | 100
Resultados 1 - 20 de 63
Filtrar
1.
Zhongguo Zhong Yao Za Zhi ; 48(21): 5681-5689, 2023 Nov.
Artigo em Chinês | MEDLINE | ID: mdl-38114164

RESUMO

Circadian rhythm refers to the daily rhythmic variations in an organism. The irregular lifestyles of modern humans have led to a high incidence of chronic diseases, highlighting an inseparable relationship between disrupted circadian rhythm and disease development. TCM has long discussed rhythmic variations, with records dating back to the Yellow Emperor's Inner Canon(Huang Di Nei Jing), which laid a rich theoretical foundation for the research on circadian rhythm. Modern medical research has provided a more comprehensive explanation of its molecular mechanisms. This article integrated the current understanding of circadian rhythm in both Chinese and western medicine, emphasizing the crucial relationship between rhythm regulation and disease treatment. By highlighting the interdisciplinary nature of the two fields, it offers new directions for exploring the field of chronomedicine.


Assuntos
Terapia por Acupuntura , Pesquisa Biomédica , Polygonatum , Humanos , Medicina Tradicional Chinesa , Ritmo Circadiano
2.
Nature ; 503(7477): 535-8, 2013 Nov 28.
Artigo em Inglês | MEDLINE | ID: mdl-24172901

RESUMO

The 2002-3 pandemic caused by severe acute respiratory syndrome coronavirus (SARS-CoV) was one of the most significant public health events in recent history. An ongoing outbreak of Middle East respiratory syndrome coronavirus suggests that this group of viruses remains a key threat and that their distribution is wider than previously recognized. Although bats have been suggested to be the natural reservoirs of both viruses, attempts to isolate the progenitor virus of SARS-CoV from bats have been unsuccessful. Diverse SARS-like coronaviruses (SL-CoVs) have now been reported from bats in China, Europe and Africa, but none is considered a direct progenitor of SARS-CoV because of their phylogenetic disparity from this virus and the inability of their spike proteins to use the SARS-CoV cellular receptor molecule, the human angiotensin converting enzyme II (ACE2). Here we report whole-genome sequences of two novel bat coronaviruses from Chinese horseshoe bats (family: Rhinolophidae) in Yunnan, China: RsSHC014 and Rs3367. These viruses are far more closely related to SARS-CoV than any previously identified bat coronaviruses, particularly in the receptor binding domain of the spike protein. Most importantly, we report the first recorded isolation of a live SL-CoV (bat SL-CoV-WIV1) from bat faecal samples in Vero E6 cells, which has typical coronavirus morphology, 99.9% sequence identity to Rs3367 and uses ACE2 from humans, civets and Chinese horseshoe bats for cell entry. Preliminary in vitro testing indicates that WIV1 also has a broad species tropism. Our results provide the strongest evidence to date that Chinese horseshoe bats are natural reservoirs of SARS-CoV, and that intermediate hosts may not be necessary for direct human infection by some bat SL-CoVs. They also highlight the importance of pathogen-discovery programs targeting high-risk wildlife groups in emerging disease hotspots as a strategy for pandemic preparedness.


Assuntos
Quirópteros/virologia , Peptidil Dipeptidase A/metabolismo , Coronavírus Relacionado à Síndrome Respiratória Aguda Grave/isolamento & purificação , Coronavírus Relacionado à Síndrome Respiratória Aguda Grave/metabolismo , Enzima de Conversão de Angiotensina 2 , Animais , China , Chlorocebus aethiops , Reservatórios de Doenças/virologia , Fezes/virologia , Imunofluorescência , Genoma Viral/genética , Especificidade de Hospedeiro , Humanos , Dados de Sequência Molecular , Pandemias/prevenção & controle , Pandemias/veterinária , Peptidil Dipeptidase A/genética , Reação em Cadeia da Polimerase em Tempo Real , Receptores Virais/genética , Receptores Virais/metabolismo , Coronavírus Relacionado à Síndrome Respiratória Aguda Grave/genética , Coronavírus Relacionado à Síndrome Respiratória Aguda Grave/ultraestrutura , Síndrome Respiratória Aguda Grave/prevenção & controle , Síndrome Respiratória Aguda Grave/transmissão , Síndrome Respiratória Aguda Grave/veterinária , Síndrome Respiratória Aguda Grave/virologia , Especificidade da Espécie , Glicoproteína da Espícula de Coronavírus/química , Glicoproteína da Espícula de Coronavírus/metabolismo , Células Vero , Vírion/isolamento & purificação , Vírion/ultraestrutura , Internalização do Vírus , Viverridae/metabolismo
3.
Aging Ment Health ; 22(9): 1232-1238, 2018 09.
Artigo em Inglês | MEDLINE | ID: mdl-28636413

RESUMO

OBJECTIVE: To explore the association between tea consumption and cognitive impairment (CoI). METHODS: 4579 adults (≥60 years) from the Weitang Geratric Diseases Study were assessed for characteristics of tea consumption and cognitive function by administering questionnaires and the Abbreviated Mental Test (AMT), respectively. We divided the subjects into normal cognitive function group (AMT score ≥8) and CoI group (AMT score ≤7).   The association between tea consumption and risk of CoI was determined by logistic regression models. RESULTS: The least-squared means of the AMT scores for the subjects who seldom consumed tea were less favorable than those who habitually consumed tea. An inverse association was found between tea consumption (of any type) and prevalence of CoI (odds ratio = 0.74, 95% confidence interval = 0.57-0.98, P = 0.032). Interestingly, the protective correlation of tea was more obvious in never smokers (odds ratio = 0.63), but vanished in current/former smokers (odds ratio = 1.10). In never smokers, frequency of tea consumption was significantly associated with CoI (P for trend = 0.010). CONCLUSION: Habitual tea consumption is suggested to be associated with a decreased risk of CoI among elders in Suzhou, and a higher frequency of tea consumption was associated with a lower prevalence of CoI among never smokers.


Assuntos
Disfunção Cognitiva/epidemiologia , Comportamento de Ingestão de Líquido , Fumar/epidemiologia , Chá , Idoso , Idoso de 80 Anos ou mais , China/epidemiologia , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Prevalência , Fatores de Proteção , Risco
4.
Sensors (Basel) ; 16(11)2016 Nov 02.
Artigo em Inglês | MEDLINE | ID: mdl-27827856

RESUMO

The characteristics of two types of surface acoustic waves SAWs (Rayleigh waves and Love waves) propagating in bilayered structures of ( 11 2 ¯ 0 ) ZnO/R-sapphire are simulated by a finite element method (FEM) model, in which both SAWs have crossed propagation directions. Furthermore, based on the bilayered structures, the frequency responses of Rayleigh wave and Love wave humidity sensors are also simulated. Meanwhile, the frequency shifts, insertion loss changes and then the sensitivities of both humidity sensors induced by the adsorbed water layer perturbations, including the mechanical and electrical factors, are calculated numerically. Generally, the characteristics and performances of both sensors are strongly dependent on the thickness of the ZnO films. By appropriate selecting the ratio of the film thickness to SAW wavelength for each kind of the sensors, the performances of both sensors can be optimized.

5.
J Acoust Soc Am ; 138(4): EL435-40, 2015 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-26520357

RESUMO

A model of thermoacoustic refrigerator on the basis of an acoustic metamaterial is presented, in which an array of side pipes is adopted to suppress harmonic waves in the thermoacoustic resonator. The array of side pipes traps the acoustic waves with Fabry-Perot resonant frequencies and induces narrow forbidden bands of transmission. When the resonant frequency of the thermoacoustic refrigerator is chosen as the operating frequency, the harmonic wave can be exactly located in the forbidden band by properly adapting the structural parameters of the system. Therefore, the component of the harmonic wave in the thermoacoustic resonator can be efficiently suppressed.

6.
Heliyon ; 10(2): e24357, 2024 Jan 30.
Artigo em Inglês | MEDLINE | ID: mdl-38293443

RESUMO

Background: Fibrosis is a heavy burden on the global healthcare system. Recently, an increasing number of studies have demonstrated that Extracellular vesicles play an important role in intercellular communication under both physiological and pathological conditions. This study aimed to explore the role of extracellular vesicles' in fibrosis using bibliometric methods. Methods: Original articles and reviews related to extracellular vesicles and fibrosis were obtained from the Web of Science Core Collection database on November 9, 2022. VOSviewer was used to obtain general information, including co-institution, co-authorship, and co-occurrence visualization maps. The CiteSpace software was used to analyze citation bursts of keywords and references, a timeline view of the top clusters of keywords and cited articles, and the dual map. R package "bibliometrix" was used to analyze annual production, citation per year, collaboration network between countries/regions, thematic evolution map, and historiography network. Results: In total, 3376 articles related to extracellular vesicles and fibrosis published from 2013 to 2022 were included in this study, with China and the United States being the top contributors. Shanghai Jiao Tong University has the highest number of publications. The main collaborators were Giovanni Camussi, Stefania Bruno, Marta Tepparo, and Cristina Grange. Journals related to molecular, biology, genetics, health, immunology, and medicine tended to publish literature on extracellular vesicles and fibrosis. "Recovery," "heterogeneity," "degradation," "inflammation," and "mesenchymal stem cells" are the keywords in this research field. Literature on extracellular vesicles and fibrosis associated with several diseases, including "kidney disease," "rheumatoid arthritis," and "skin regeneration" may be the latest hot research field. Conclusions: This study provides a comprehensive perspective on extracellular vesicles and fibrosis through a bibliometric analysis of articles published between 2013 and 2022. We identified the most influential countries, institutions, authors, and journals. We provide information on recent research frontiers and trends for scholars interested in the field of extracellular vesicles and fibrosis. Their role in biological processes has great potential to initiate a new upsurge in future research.

7.
Biosci Biotechnol Biochem ; 77(6): 1251-7, 2013.
Artigo em Inglês | MEDLINE | ID: mdl-23748768

RESUMO

The bar-headed goose, a specialized high-altitude species, has a capacity for high oxygen uptake from a hypoxic environment. It thus has a higher oxygen affinity than other bird species of lower-altitude environments. Oxygen affinity is determined by molecular structures and genetic mutations of hemoglobin (Hb), which can also influence the coordinating structures and dynamics of oxygen-Hb. To explore the structural differences in Hbs as between high and low altitude species, photolysis dynamic parameters, including quantum yield, enthalpy, and conformational volume changes in carboxy-Hbs (HbCO) for the bar-headed goose and low altitude counterparts (the Chinese goose and chicken) were investigated by the laser pumping-probing technique and photoacoustic calorimetry. Comparing the photolysis results for HbCO of the three species, the enthalpy and conformational volume changes of the bar-headed goose were much smaller than those of the others, although the quantum yields of all three species are similar. To explain the possible mechanisms of these differences, modifications of salt bridges and key residue mutations at the α ß subunit interfaces of the proteins are described and discussed briefly.


Assuntos
Altitude , Gansos/fisiologia , Hemoglobinas/metabolismo , Consumo de Oxigênio , Animais , Gansos/genética , Hemoglobinas/química , Lasers , Fotólise , Especificidade da Espécie , Termodinâmica , Ultrassom/métodos
8.
J Acoust Soc Am ; 133(6): 3846-52, 2013 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-23742339

RESUMO

Nonlinear acoustic fields in transmission-line acoustic metamaterials based on a cylindrical pipe with periodically arranged side holes are studied, in which the dispersions and characteristic parameters of the nonlinear acoustic waves are obtained with the Bloch theory, and meanwhile the distributions of the fundamental wave (FW) and second harmonic wave (SHW) in the metamaterial are simulated. Three characteristic frequency bands are defined according to the relations between the frequencies of the FW, SHW, and the low-frequency forbidden band (LFB) in the metamaterial. Especially, when the FW is in the LFB while the SHW is outside the LFB, the SHW can transmit through the metamaterial although the FW is blocked, which exhibits the possibility to extract the information from the SHW instead of the FW. In addition, experiments are carried out to measure the distributions of the acoustic pressures for the FW and SHW along the metamaterial and the experimental results are in agreement with the theory.

9.
Histol Histopathol ; 38(1): 9-28, 2023 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-35880756

RESUMO

There are two kinds of toxins in sea anemones: neurotoxins and pore forming toxins. As a representative of the sodium channel toxin, the neurotoxin ATX II in neurotoxin mainly affects the process of action potential and the release of transmitter to affect the inactivation of the sodium channel. As the representatives of potassium channel toxins, BgK and ShK mainly affect the potassium channel current. EqTx and Sticholysins are representative of pore forming toxins, which can form specific ion channels in cell membranes and change the concentration of internal and external ions, eventually causing hemolytic effects. Based on the above mechanism, toxins such as ATX II can also cause toxic effects in tissues and organs such as heart, lung and muscle. As an applied aspect it was shown that sea anemone toxins often have strong toxic effects on tumor cells, induce cancer cells to enter the pathway of apoptosis, and can also bind to monoclonal antibodies or directly inhibit relevant channels for the treatment of autoimmune diseases.


Assuntos
Neurotoxinas , Anêmonas-do-Mar , Animais , Neurotoxinas/toxicidade , Neurotoxinas/metabolismo , Anêmonas-do-Mar/metabolismo , Canais de Sódio/metabolismo , Canais de Sódio/farmacologia , Canais de Potássio/metabolismo , Canais de Potássio/farmacologia , Membrana Celular/metabolismo
10.
Ying Yong Sheng Tai Xue Bao ; 34(7): 1923-1931, 2023 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-37694476

RESUMO

The rapid and extensive urbanization has profound impacts on urban thermal environment. It is of great significance to comprehensively understand how urbanization affects the evolution of urban thermal environment for urban ecological safety, environmental quality, and residents' health. Based on daily land surface temperature (LST) products of MODIS Aqua satellite in the summer of 2002-2020, we investigated the evolution of urban-rural differences in surface summer thermal environment in Shanghai during 2002-2020 and its response to urban spatial renewal. We used normalized land surface temperature (NLST) and urban heat island ratio index (URI) as the surface thermal environment measurement indicators, by combining vegetation index and impervious surface cove-rage, and used M-K trend analysis and interpretation analysis. The results showed that the linear growth rate of LST in Shanghai was 0.09 ℃·a-1 (2002-2020), and that URI showed a trend of first increasing (2002-2010) and then decreasing (2010-2020). The mean summer LST was generally in the order of urban core>suburban>rural. 1.6% of the areas showed a significant cooling trend, of which 54.0% were distributed in the urban core. 39.5% of the regions showed a significant warming trend, of which 77.6% were distributed in the suburban. In general, there were concentrated significant cooling areas in the highly urbanized urban areas, while there was a significant warming trend in the suburban. The transformation from urban expansion to urban renewal was the main reason for the emergence of concentrated and significant cooling areas in the urban. Nearly 20% of the urban area showed a signi-ficant increase of vegetation coverage. Urban renewal projects such as gathering vegetation or dispersing impervious surfaces in highly urbanized areas are important ways to effectively improve the urban residential thermal environment.


Assuntos
Temperatura Alta , Reforma Urbana , Cidades , China , Temperatura Baixa
11.
J Acoust Soc Am ; 132(5): EL358-63, 2012 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-23145695

RESUMO

The potential operating conditions of acoustic dual-negative refraction (ADNR) are investigated by band structure theory for scatterers with different shapes and symmetries. Specifically, two types of lattices (triangular and honeycomb) and four different shapes of scatterers (circle, hexagon, square and triangle) are considered. Based on the generation mechanism of the ADNR effect, which is dependent on the frequency of the incident wave at the overlapping second and third Bloch bands, the optimum operating frequencies of ADNR with different crystal structures are given. The calculations demonstrate that the ADNR effect can be generated at the normalized frequency from 0.8 to 1.05.


Assuntos
Acústica , Modelos Teóricos , Som , Acústica/instrumentação , Desenho de Equipamento , Estrutura Molecular , Movimento (Física) , Pressão , Espalhamento de Radiação , Aço Inoxidável , Fatores de Tempo , Água
12.
J Acoust Soc Am ; 131(2): EL150-5, 2012 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-22352615

RESUMO

A two-dimensional cylindrical acoustic concentrator is designed with multilayered alternative homogeneous materials, which can focus acoustic field and enhance acoustic energy in a given area. The frequency response analysis of the acoustic concentrator demonstrates that the acoustic energy can be concentrated within the device over a wide frequency band. Meanwhile, there are contradictory relations between the acoustic concentrating performances in the inner region and the scattering properties in the outer region of these concentrators. When the contradictory relations satisfy compromise balance, the concentration ratio can reach at least 70%.

13.
Chem Commun (Camb) ; 58(32): 4954-4957, 2022 Apr 19.
Artigo em Inglês | MEDLINE | ID: mdl-35299235

RESUMO

Herein, we propose the required general pore features for one-step C2H4 production from a C2 hydrocarbon mixture, such as: (i) a non-metallic binding site; (ii) polar pore surface; and (iii) narrow pocket. Four representative MOFs (Ni-BDC-INA, CPM-173, UiO-66, and DMOF-1) and two counterexamples (MOF-74-Co and IISERP-MOF2) were selected to verify this concept, by conducting single-component gas adsorption measurements, multiple-component breakthrough experiments, and molecular simulations. The established pore features are a stepping-stone for the design and synthesis of new MOFs with improved performance for C2H4 separation.

14.
J Inflamm Res ; 15: 2229-2241, 2022.
Artigo em Inglês | MEDLINE | ID: mdl-35411168

RESUMO

Background: Various preoperative inflammatory indicators have been identified as potential predictors of poor prognosis in patients with hepatocellular carcinoma (HCC), but the role of postoperative inflammatory indicators remains unclear. This study aimed to explore the prognostic value of the postoperative lymphocyte-C-reactive protein ratio (PostLCR) on its own and combined with preoperative LCR (PreLCR). Methods: A total of 290 patients with primary HCC were retrospectively enrolled in the study. Univariate analysis was used to identify factors significantly associated with poor disease-free survival (DFS) and overall survival (OS), then multivariate analysis was performed to identify independent prognostic indicators of poor survival. Prognostic models based on preoperative, postoperative, and both types of indicators were then constructed, and their predictive performance were evaluated using time-dependent receiver operating characteristic curves and the concordance index (C-index). Results: PreLCR and PostLCR levels correlated with DFS and OS more strongly than other pre- and postoperative inflammatory indicators, respectively. Decreased PreLCR and PostLCR were independent prognostic factors for both DFS and OS, while HCC patients with decreased PreLCR and PostLCR had worse prognosis than patients with increased PreLCR and PostLCR. Patients into three groups based on their cut-off values of PreLCR and PostLCR, Kaplan-Meier survival analysis indicated that HCC patients with low PreLCR and PostLCR had the worst DFS and OS. The combined model showed better predictive performance at 1 and 3 years post-surgery than individual pre- and postoperative models, the American Joint Committee on Cancer/Tumor-Node-Metastasis (8th edition) staging system and the Barcelona Clinic Liver Cancer system. The combine model demonstrated a markedly superior C-index compared with the other models in DFS and OS. Conclusion: Our study showed PreLCR and PostLCR are independent predictors of DFS and OS in HCC patients after partial hepatectomy. Models that include both PreLCR and PostLCR can predict prognosis better than well-established clinical staging systems.

15.
Sci Rep ; 12(1): 19034, 2022 Nov 08.
Artigo em Inglês | MEDLINE | ID: mdl-36347855

RESUMO

It is challenging to insulate sound transmission in low frequency-bands without blocking the air flow in a pipe. In this work, a small and light membrane-based cubic sound insulator is created to block acoustic waves in multiple low frequency-bands from 200 to 800 Hz in pipes. Due to distinct vibration modes of the membrane-type faces of the insulator and co-action of acoustic waves transmitting along different paths, large sound attenuation is achieved in multiple frequency-bands, and the maximum transmission loss reaches 25 dB. Furthermore, because the sound insulator with a deep subwavelength size is smaller than the cross-sectional area of the pipe, it does not block ventilation along the pipe.

16.
Int J Ophthalmol ; 15(3): 426-431, 2022.
Artigo em Inglês | MEDLINE | ID: mdl-35310059

RESUMO

AIM: To investigate the ocular development of patients who had unilateral congenital cataract (CC) combined with persistent fetal vasculature (PFV). METHODS: This cross-sectional, observational study included patients who had unilateral CC and PFV and those with isolated unilateral CC. Axial length (AL), keratometry, anterior chamber depth (ACD), lens thickness, and vitreous length were obtained. The ocular biometric parameters of the affected eyes of patients with CC and PFV were compared with the fellow eyes and with the affected eyes of patients with isolated CC. RESULTS: A total of 110 patients were included and divided into 4 groups: group 1 (18 patients with CC and PFV, <24mo), group 2 (22 patients with CC and PFV, ≥24mo), group 3 (35 patients with CC, <24mo), and group 4 (35 patients with CC, ≥24mo). The ALs of the affected eyes were shorter than those of the fellow eyes in group 1 (20.02±1.06 vs 20.66±0.63 mm, P=0.025). While the ALs of the affected eyes were longer than those of the fellow eyes in group 2 (23.18±2.00 vs 22.31±1.06 mm, P=0.044) and group 4 (22.64±1.80 vs 22.02±1.01 mm, P=0.033). The keratometries of the affected eyes were steeper than those of the fellow eyes in group 2 (44.78±1.66 vs 43.83±1.38 D, P=0.041) and group 4 (43.76±1.91 vs 43.34±1.46 D, P=0.043). No difference of ACDs between two eyes was found in all groups (all P>0.05). CONCLUSION: Compared with the fellow eyes, the ALs of the eyes with unilateral CC and PFV are shorter in patients younger than 24mo and longer in those older than 24mo; the keratometries of the eyes with unilateral CC and PFV are steeper in patients older than 24mo and similar with those younger than 24mo. These findings provide further understanding of ocular development in patients with both CC and PFV.

17.
Oncol Rep ; 46(4)2021 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-34368874

RESUMO

Long noncoding RNA (lncRNA) CDKN2B­antisense RNA 1 (AS1) functions as a tumor oncogene in numerous cancers. However, the roles and mechanism of CDKN2B­AS1 in colorectal cancer (CRC) have not been explored. The present study aimed to investigate whether and how CDKN2B­AS1 contributes to CRC progression. The data revealed that CDKN2B­AS1 expression was upregulated in CRC tissues. Loss­of­function assays demonstrated that CDKN2B­AS1 in CRC modulated cell proliferation and apoptosis, which was mediated by cyclin D1, cyclin­dependent kinase (CDK) 4, p­Rb, caspase­9 and caspase­3. Bioinformatics analysis and luciferase reporter assays indicated direct binding of microRNA (miR)­28­5p to CDKN2B­AS1. Moreover, the results herein revealed that the expression of miR­28­5p was negatively correlated with that of CDKN2B­AS1 in CRC tissue. Moreover, CDKN2B­AS1 acted as a miR­28­5p competing endogenous RNA (ceRNA) to target and regulate the expression of URGCP. These findings indicated that CDKN2B­AS1 plays roles in CRC progression, providing a potential therapeutic target or novel diagnostic biomarker for CRC.


Assuntos
Apoptose/genética , Proliferação de Células/genética , Neoplasias Colorretais/genética , MicroRNAs/metabolismo , RNA Longo não Codificante/metabolismo , Adulto , Idoso , Caspases/metabolismo , Linhagem Celular Tumoral , Ciclina D1/metabolismo , Progressão da Doença , Feminino , Regulação Neoplásica da Expressão Gênica , Humanos , Mutação com Perda de Função , Masculino , Pessoa de Meia-Idade , Regulação para Cima
18.
Sci Rep ; 11(1): 2404, 2021 Jan 28.
Artigo em Inglês | MEDLINE | ID: mdl-33510213

RESUMO

It is challenging to increase the sensitivity of a hydrogen sensor operating at room temperature due to weak sorption and tiny mass of hydrogen. In this work, an ultrasonic sensor is presented for detecting hydrogen, which is composed of a 128° YX-LiNbO3 substrate and a reduced graphene oxide (RGO) sensitive layer with a platinum catalyzer. By optimizing the depositing parameters of RGO and platinum, a considerably high sensitivity is achieved at room temperature. A frequency shift of 308.9 kHz is obtained in 100 ppm hydrogen mixed with argon, and a frequency shift of 24.4 kHz is obtained in 1000 ppm hydrogen mixed in synthetic air. It is demonstrated that in addition to strong sorption of the sensitive layer, the coaction of mass load and conductivity variation is key to high sensitivity of the sensor. By establishing the original conductivity of the sensitive layer within the "conductivity window" for enhancing electrical response, we improve the sensitivity of the ultrasonic sensor, which is available for detecting hydrogen with an extremely low concentration of 5 ppm.

19.
J Virol ; 82(4): 1899-907, 2008 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-18077725

RESUMO

Severe acute respiratory syndrome (SARS) is caused by the SARS-associated coronavirus (SARS-CoV), which uses angiotensin-converting enzyme 2 (ACE2) as its receptor for cell entry. A group of SARS-like CoVs (SL-CoVs) has been identified in horseshoe bats. SL-CoVs and SARS-CoVs share identical genome organizations and high sequence identities, with the main exception of the N terminus of the spike protein (S), known to be responsible for receptor binding in CoVs. In this study, we investigated the receptor usage of the SL-CoV S by combining a human immunodeficiency virus-based pseudovirus system with cell lines expressing the ACE2 molecules of human, civet, or horseshoe bat. In addition to full-length S of SL-CoV and SARS-CoV, a series of S chimeras was constructed by inserting different sequences of the SARS-CoV S into the SL-CoV S backbone. Several important observations were made from this study. First, the SL-CoV S was unable to use any of the three ACE2 molecules as its receptor. Second, the SARS-CoV S failed to enter cells expressing the bat ACE2. Third, the chimeric S covering the previously defined receptor-binding domain gained its ability to enter cells via human ACE2, albeit with different efficiencies for different constructs. Fourth, a minimal insert region (amino acids 310 to 518) was found to be sufficient to convert the SL-CoV S from non-ACE2 binding to human ACE2 binding, indicating that the SL-CoV S is largely compatible with SARS-CoV S protein both in structure and in function. The significance of these findings in relation to virus origin, virus recombination, and host switching is discussed.


Assuntos
Quirópteros/virologia , Peptidil Dipeptidase A/metabolismo , Receptores Virais/metabolismo , Coronavírus Relacionado à Síndrome Respiratória Aguda Grave/fisiologia , Proteínas Virais/metabolismo , Internalização do Vírus , Sequência de Aminoácidos , Enzima de Conversão de Angiotensina 2 , Animais , Linhagem Celular , Quimera/genética , Quimera/fisiologia , Clonagem Molecular , HIV/genética , Células HeLa , Humanos , Camundongos , Dados de Sequência Molecular , Peptidil Dipeptidase A/análise , Peptidil Dipeptidase A/genética , Mapeamento de Interação de Proteínas , Ratos , Receptores Virais/análise , Receptores Virais/genética , Coronavírus Relacionado à Síndrome Respiratória Aguda Grave/genética , Montagem de Vírus , Viverridae/virologia
20.
Biochem Genet ; 47(3-4): 257-65, 2009 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-19184672

RESUMO

Bats are the only mammals with the capacity for powered flight. When flying, they need abundant energy and oxygen. According to previous works, the hemoglobin (Hb) oxygen loading function of bats is insensitive to variations in body temperature, although different bat species have different heat sensitivity. We cloned Hb alpha-chain sequences from eight bat species to investigate whether they have different characteristics. We found that Hb in the bat lineages is under purifying selection, which accords with the importance of its function in bats. Three turn regions in bat Hb, however, have distinct evolutionary rates compared with those of other mammals, and the codons in these regions have an accelerated rate of evolution. These codons are under divergent selection in bats. These changes in Hb may have occurred in response to the physiological requirements of the species concerned, as adaptations to different lifestyles.


Assuntos
Quirópteros/genética , alfa-Globinas/genética , Animais , Sequência de Bases , Clonagem Molecular , Evolução Molecular , Humanos , Modelos Moleculares , Dados de Sequência Molecular , Alinhamento de Sequência
SELEÇÃO DE REFERÊNCIAS
Detalhe da pesquisa