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2.
Phys Rev Lett ; 126(25): 257002, 2021 Jun 25.
Artigo em Inglês | MEDLINE | ID: mdl-34241500

RESUMO

We report the observation of discrete bound states with the energy levels deviating from the widely believed ratio of 1∶3∶5 in the vortices of an iron-based superconductor KCa_{2}Fe_{4}As_{4}F_{2} through scanning tunneling microscopy (STM). Meanwhile Friedel oscillations of vortex bound states are also observed for the first time in related vortices. By doing self-consistent calculations of Bogoliubov-de Gennes equations, we find that at extreme quantum limit, the superconducting order parameter exhibits a Friedel-like oscillation, which modifies the energy levels of the vortex bound states and explains why it deviates from the ratio of 1∶3∶5. The observed Friedel oscillations of the bound states can also be roughly interpreted by the theoretical calculations, however some features at high energies could not be explained. We attribute this discrepancy to the high energy bound states with the influence of nearby impurities. Our combined STM measurement and the self-consistent calculations illustrate a generalized feature of vortex bound states in type-II superconductors.

3.
Phys Rev Lett ; 126(3): 037201, 2021 Jan 22.
Artigo em Inglês | MEDLINE | ID: mdl-33543946

RESUMO

Sr_{2}CuTeO_{6} is a square-lattice Néel antiferromagnet with superexchange between first-neighbor S=1/2 Cu spins mediated by plaquette centered Te ions. Substituting Te by W, the affected impurity plaquettes have predominantly second-neighbor interactions, thus causing local magnetic frustration. Here we report a study of Sr_{2}CuTe_{1-x}W_{x}O_{6} using neutron diffraction and µSR techniques, showing that the Néel order vanishes already at x=0.025±0.005. We explain this extreme order suppression using a two-dimensional Heisenberg spin model, demonstrating that a W-type impurity induces a deformation of the order parameter that decays with distance as 1/r^{2} at temperature T=0. The associated logarithmic singularity leads to loss of order for any x>0. Order for small x>0 and T>0 is induced by weak interplane couplings. In the nonmagnetic phase of Sr_{2}CuTe_{1-x}W_{x}O_{6}, the µSR relaxation rate exhibits quantum critical scaling with a large dynamic exponent, z≈3, consistent with a random-singlet state.

4.
Rev Sci Instrum ; 91(12): 123901, 2020 Dec 01.
Artigo em Inglês | MEDLINE | ID: mdl-33379959

RESUMO

We report a new design of a temperature-modulated dilatometer, which obtains the linear thermal expansion coefficient by measuring the oscillating changes of the sample's length and temperature by using a piezobender and a thermocouple, respectively. Using an iron-based superconductor KFe2As2 as an example, we show that this device is able to measure thin samples with high resolutions at low temperatures and high magnetic fields. Despite its incapability of giving absolute values, the new dilatometer provides a high-resolution method to study many important physical properties in condensed matter physics, such as thermal and quantum phase transitions and vortex dynamics in the superconducting state. The prototype design of this device can be further improved in many aspects to meet particular requirements.

5.
Phys Rev Lett ; 125(11): 117002, 2020 Sep 11.
Artigo em Inglês | MEDLINE | ID: mdl-32975969

RESUMO

The neutron spin resonance is generally regarded as a key to understanding the magnetically mediated Cooper pairing in unconventional superconductors. Here, we report an inelastic neutron scattering study on the low-energy spin excitations in a quasi-two-dimensional iron-based superconductor KCa_{2}Fe_{4}As_{4}F_{2}. We have discovered a two-dimensional spin resonant mode with downward dispersions, a behavior closely resembling the low branch of the hourglass-type spin resonance in cuprates. While the resonant intensity is predominant by two broad incommensurate peaks near Q=(0.5,0.5) with a sharp energy peak at E_{R}=16 meV, the overall energy dispersion of the mode exceeds the measured maximum total gap Δ_{tot}=|Δ_{k}|+|Δ_{k+Q}|. These results deeply challenge the conventional understanding of the resonance modes as magnetic excitons regardless of underlining pairing symmetry schemes, and it also points out that when the iron-based superconductivity becomes very quasi-two-dimensional, the electronic behaviors are similar to those in cuprates.

6.
Phys Rev Lett ; 124(20): 206602, 2020 May 22.
Artigo em Inglês | MEDLINE | ID: mdl-32501105

RESUMO

We report heat capacity measurements of SrCu_{2}(BO_{3})_{2} under high pressure along with simulations of relevant quantum spin models and map out the (P,T) phase diagram of the material. We find a first-order quantum phase transition between the low-pressure quantum dimer paramagnet and a phase with signatures of a plaquette-singlet state below T=2 K. At higher pressures, we observe a transition into a previously unknown antiferromagnetic state below 4 K. Our findings can be explained within the two-dimensional Shastry-Sutherland quantum spin model supplemented by weak interlayer couplings. The possibility to tune SrCu_{2}(BO_{3})_{2} between the plaquette-singlet and antiferromagnetic states opens opportunities for experimental tests of quantum field theories and lattice models involving fractionalized excitations, emergent symmetries, and gauge fluctuations.

7.
Vaccine ; 37(19): 2561-2568, 2019 05 01.
Artigo em Inglês | MEDLINE | ID: mdl-30955980

RESUMO

BACKGROUND: Influenza A/H7N9 viruses are undergoing antigenic drift since their emergence in 2013, and vaccination strategies are needed for pandemic preparedness. Two doses of adjuvanted monovalent inactivated influenza A/H7N9 vaccine (IIV1 A/H7N9) are needed for optimal serological responses. However, administering 2 doses in a pandemic setting might be challenging. We evaluated the immunogenicity of "boosting" with IIV1 A/H7N9 in subjects "primed" 8 years previously with IIV1 A/H7N7. METHODS: We administered 1 booster dose containing 45 mcg of IIV1 A/H7N9 hemagglutinin to 17 recipients of 2 prior doses of IIV1 A/H7N7, and to 10 influenza A/H7-naïve subjects. We tested their post-boosting sera for antibodies (Ab) against homologous influenza A/H7N9 using a hemagglutination inhibition assay; and compared their Ab titers to those in stored sera from recipients of AS03-adjuvanted IIV1 A/H7N9 against 9 strains of influenza A/H7N9 viruses. RESULTS: The percentage of subjects with Ab titers ≥40 on Days 9 and 29 post boosting, respectively, was 65% and 41% in primed subjects and 10% and 0% in unprimed subjects. The Ab titers in recipients of AS03-adjuvanted IIV1 A/H7N9 were higher than those in the prime-boost group against a panel of influenza A/H7N9 viruses, except for 2 highly pathogenic strains. CONCLUSIONS: Priming with IIV1 A/H7 results in serological responses following a delayed boost with 1 dose of unadjuvanted IIV1 A/H7N9, despite lack of antibody response after the prime. Optimizing prime-boost approaches would benefit pandemic preparedness. ClinicalTrials.gov identifier: NCT02586792.


Assuntos
Imunização Secundária , Imunogenicidade da Vacina , Vírus da Influenza A Subtipo H7N7/imunologia , Subtipo H7N9 do Vírus da Influenza A/imunologia , Vacinas contra Influenza/imunologia , Influenza Humana/prevenção & controle , Adulto , Anticorpos Neutralizantes , Anticorpos Antivirais , Feminino , Testes de Inibição da Hemaglutinação , Humanos , Vacinas contra Influenza/administração & dosagem , Vacinas contra Influenza/efeitos adversos , Masculino , Pessoa de Meia-Idade , Avaliação de Resultados da Assistência ao Paciente , Vacinação , Fluxo de Trabalho
9.
J Virol ; 90(7): 3506-14, 2016 Jan 13.
Artigo em Inglês | MEDLINE | ID: mdl-26764002

RESUMO

UNLABELLED: The H9N2 influenza viruses that are enzootic in terrestrial poultry in China pose a persistent pandemic threat to humans. To investigate whether the continuous circulation and adaptation of these viruses in terrestrial poultry increased their infectivity to pigs, we conducted a serological survey in pig herds with H9N2 viruses selected from the aquatic avian gene pool (Y439 lineage) and the enzootic terrestrial poultry viruses (G1 and Y280 lineages). We also compared the infectivity and transmissibility of these viruses in pigs. It was found that more than 15% of the pigs sampled from 2010 to 2012 in southern China were seropositive to either G1 or Y280 lineage viruses, but none of the sera were positive to the H9 viruses from the Y439 lineage. Viruses of the G1 and Y280 lineages were able to infect experimental pigs, with detectable nasal shedding of the viruses and seroconversion, whereas viruses of the Y439 lineage did not cause a productive infection in pigs. Thus, adaptation and prevalence in terrestrial poultry could lead to interspecies transmission of H9N2 viruses from birds to pigs. Although H9N2 viruses do not appear to be continuously transmissible among pigs, repeated introductions of H9 viruses to pigs naturally increase the risk of generating mammalian-adapted or reassorted variants that are potentially infectious to humans. This study highlights the importance of monitoring the activity of H9N2 viruses in terrestrial poultry and pigs. IMPORTANCE: H9N2 subtype of influenza viruses has repeatedly been introduced into mammalian hosts, including humans and pigs, so awareness of their activity and evolution is important for influenza pandemic preparedness. However, since H9N2 viruses usually cause mild or even asymptomatic infections in mammalian hosts, they may be overlooked in influenza surveillance. Here, we found that the H9N2 viruses established in terrestrial poultry had higher infectivity in pigs than those from aquatic birds, which suggests that adaptation of the H9N2 viruses in terrestrial poultry might have increased the infectivity of the virus to mammals. Therefore, monitoring the prevalence and evolution of H9 viruses prevalent in terrestrial birds and conducting risk assessment of their threat to mammals are critical for evaluating the pandemic potential of this virus.


Assuntos
Vírus da Influenza A Subtipo H9N2/patogenicidade , Influenza Aviária/transmissão , Infecções por Orthomyxoviridae/transmissão , Infecções por Orthomyxoviridae/veterinária , Doenças das Aves Domésticas/transmissão , Doenças dos Suínos/virologia , Animais , Embrião de Galinha , China , Humanos , Influenza Aviária/virologia , Influenza Humana/virologia , Infecções por Orthomyxoviridae/virologia , Aves Domésticas/virologia , Doenças das Aves Domésticas/virologia , Suínos
10.
Bing Du Xue Bao ; 31(4): 357-62, 2015 Jul.
Artigo em Chinês | MEDLINE | ID: mdl-26524907

RESUMO

To explore the impact of the history of infection by the influenza A virus subtype H1N1 on secondary infection by the influenza A virus subtype H9N2, pigs non-infected and pre-infected with H1N1 were inoculated with H9N2 in parallel to compare nasal shedding and seroconversion patterns. Unlike pigs without a background of H1N1 infection, nasal shedding was not detected in pigs pre-infected with H1N1. Both groups generated antibodies against H9N2. However, levels of H1N1 antibodies in pigs pre-infected with H1N1 increased quickly and dramatically after challenge with H9N2. Cross-reaction was not observed between H1N1 antibodies and H9N2 viruses. These findings suggest that circulation of the H1N1 virus might be a barrier to the introduction and transmission of the avian H9N2 virus, thereby delaying its adaptation in pigs.


Assuntos
Vírus da Influenza A Subtipo H1N1/imunologia , Vírus da Influenza A Subtipo H1N1/fisiologia , Vírus da Influenza A Subtipo H9N2/imunologia , Infecções por Orthomyxoviridae/imunologia , Suínos/imunologia , Suínos/virologia , Animais , Anticorpos Antivirais/imunologia , Reações Cruzadas , Soros Imunes/imunologia , Infecções por Orthomyxoviridae/sangue , Especificidade da Espécie
11.
Sci Rep ; 5: 14170, 2015 Sep 22.
Artigo em Inglês | MEDLINE | ID: mdl-26391278

RESUMO

The ongoing avian H7N9 influenza outbreaks in China have caused significant human fatal cases and the virus is becoming established in poultry. Mutations with potential to increase mammalian adaptation have occurred in the polymerase basic protein 2 (PB2) and other viral genes. Here we found that dual 627K and 701N mutations could readily occur during transmission of the virus among ferrets via direct physical contact, and these mutations conferred higher polymerase activity and improved viral replication in mammalian cells, and enhanced virulence in mice. Special attention needs to be paid to patients with such mutations, as these may serve as an indicator of higher virus replication and increased pathogenicity.


Assuntos
Códon , Subtipo H7N9 do Vírus da Influenza A/fisiologia , Subtipo H7N9 do Vírus da Influenza A/patogenicidade , Mutação , Infecções por Orthomyxoviridae/virologia , RNA Polimerase Dependente de RNA/genética , Proteínas Virais/genética , Animais , Modelos Animais de Doenças , Ativação Enzimática , Furões , Humanos , Camundongos , Infecções por Orthomyxoviridae/mortalidade , Infecções por Orthomyxoviridae/transmissão , RNA Polimerase Dependente de RNA/metabolismo , Recombinação Genética , Temperatura , Tropismo Viral , Virulência/genética , Replicação Viral , Eliminação de Partículas Virais
12.
Nature ; 522(7554): 102-5, 2015 Jun 04.
Artigo em Inglês | MEDLINE | ID: mdl-25762140

RESUMO

Since 2013 the occurrence of human infections by a novel avian H7N9 influenza virus in China has demonstrated the continuing threat posed by zoonotic pathogens. Although the first outbreak wave that was centred on eastern China was seemingly averted, human infections recurred in October 2013 (refs 3-7). It is unclear how the H7N9 virus re-emerged and how it will develop further; potentially it may become a long-term threat to public health. Here we show that H7N9 viruses have spread from eastern to southern China and become persistent in chickens, which has led to the establishment of multiple regionally distinct lineages with different reassortant genotypes. Repeated introductions of viruses from Zhejiang to other provinces and the presence of H7N9 viruses at live poultry markets have fuelled the recurrence of human infections. This rapid expansion of the geographical distribution and genetic diversity of the H7N9 viruses poses a direct challenge to current disease control systems. Our results also suggest that H7N9 viruses have become enzootic in China and may spread beyond the region, following the pattern previously observed with H5N1 and H9N2 influenza viruses.


Assuntos
Galinhas/virologia , Evolução Molecular , Subtipo H7N9 do Vírus da Influenza A/genética , Subtipo H7N9 do Vírus da Influenza A/isolamento & purificação , Influenza Aviária/epidemiologia , Influenza Aviária/virologia , Animais , China/epidemiologia , Ecossistema , Genótipo , Humanos , Subtipo H7N9 do Vírus da Influenza A/classificação , Influenza Aviária/transmissão , Influenza Humana/epidemiologia , Influenza Humana/transmissão , Influenza Humana/virologia , Dados de Sequência Molecular , Vírus Reordenados/genética , Vírus Reordenados/isolamento & purificação , Zoonoses/transmissão , Zoonoses/virologia
13.
J Virol ; 89(7): 3534-41, 2015 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-25589662

RESUMO

UNLABELLED: The cases of human infections with H10N8 viruses identified in late 2013 and early 2014 in Jiangxi, China, have raised concerns over the origin, prevalence, and development of these viruses in this region. Our long-term influenza surveillance of poultry and migratory birds in southern China in the past 12 years showed that H10 influenza viruses have been introduced from migratory to domestic ducks over several winter seasons at sentinel duck farms at Poyang Lake, where domestic ducks share their water body with overwintering migratory birds. H10 viruses were never detected in terrestrial poultry in our survey areas until August 2013, when they were identified at live-poultry markets in Jiangxi. Since then, we have isolated 124 H10N8 or H10N6 viruses from chickens at local markets, revealing an ongoing outbreak. Phylogenetic analysis of H10 and related viruses showed that the chicken H10N8 viruses were generated through multiple reassortments between H10 and N8 viruses from domestic ducks and the enzootic chicken H9N2 viruses. These chicken reassortant viruses were highly similar to the human isolate, indicating that market chickens were the source of human infection. Recently, the H10 viruses further reassorted, apparently with H5N6 viruses, and generated an H10N6 variant. The emergence and prevalence of H10 viruses in chickens and the occurrence of human infections provide direct evidence of the threat from the current influenza ecosystem in China. IMPORTANCE: After the outbreak of avian-origin H7N9 influenza viruses in China, fatal human infections with a novel H10N8 virus were reported. Utilizing data from 12 years of influenza surveillance in southern China, we showed that H10 viruses were regularly introduced by migratory ducks to domestic ducks on Poyang Lake, a major aggregative site of migratory birds in Asia. The H10 viruses were maintained and amplified in domestic ducks and then transmitted to chickens and reassorted with enzootic H9N2 viruses, leading to an outbreak and human infections at live-poultry markets. The emergence of the H10N8 virus, following a pathway similar to that of the recent H7N9 virus, highlights the role of domestic ducks and the current influenza ecosystem in China that facilitates influenza viruses moving from their reservoir hosts through the live-poultry system to cause severe consequences for public health.


Assuntos
Glicoproteínas de Hemaglutininação de Vírus da Influenza/análise , Glicoproteínas de Hemaglutininação de Vírus da Influenza/genética , Vírus da Influenza A/classificação , Influenza Aviária/virologia , Influenza Humana/virologia , Animais , Galinhas , China/epidemiologia , Patos , Monitoramento Epidemiológico , Humanos , Vírus da Influenza A/isolamento & purificação , Influenza Aviária/epidemiologia , Influenza Humana/epidemiologia , Vírus Reordenados/classificação , Vírus Reordenados/isolamento & purificação
14.
Nature ; 502(7470): 241-4, 2013 Oct 10.
Artigo em Inglês | MEDLINE | ID: mdl-23965623

RESUMO

A novel H7N9 influenza A virus first detected in March 2013 has since caused more than 130 human infections in China, resulting in 40 deaths. Preliminary analyses suggest that the virus is a reassortant of H7, N9 and H9N2 avian influenza viruses, and carries some amino acids associated with mammalian receptor binding, raising concerns of a new pandemic. However, neither the source populations of the H7N9 outbreak lineage nor the conditions for its genesis are fully known. Using a combination of active surveillance, screening of virus archives, and evolutionary analyses, here we show that H7 viruses probably transferred from domestic duck to chicken populations in China on at least two independent occasions. We show that the H7 viruses subsequently reassorted with enzootic H9N2 viruses to generate the H7N9 outbreak lineage, and a related previously unrecognized H7N7 lineage. The H7N9 outbreak lineage has spread over a large geographic region and is prevalent in chickens at live poultry markets, which are thought to be the immediate source of human infections. Whether the H7N9 outbreak lineage has, or will, become enzootic in China and neighbouring regions requires further investigation. The discovery here of a related H7N7 influenza virus in chickens that has the ability to infect mammals experimentally, suggests that H7 viruses may pose threats beyond the current outbreak. The continuing prevalence of H7 viruses in poultry could lead to the generation of highly pathogenic variants and further sporadic human infections, with a continued risk of the virus acquiring human-to-human transmissibility.


Assuntos
Vírus da Influenza A/classificação , Vírus da Influenza A/genética , Influenza Humana/virologia , Filogenia , Animais , Galinhas , China , Patos , Genes Virais/genética , Humanos , Vírus da Influenza A Subtipo H7N7/classificação , Vírus da Influenza A Subtipo H7N7/genética , Vírus da Influenza A Subtipo H9N2/classificação , Vírus da Influenza A Subtipo H9N2/genética , Influenza Aviária/transmissão , Influenza Aviária/virologia , Influenza Humana/transmissão , Dados de Sequência Molecular , Vírus Reordenados/classificação , Vírus Reordenados/genética
15.
Guang Pu Xue Yu Guang Pu Fen Xi ; 33(3): 628-31, 2013 Mar.
Artigo em Chinês | MEDLINE | ID: mdl-23705421

RESUMO

Nano-rutile TiO2 photocatalysts with bigger specific surface area were prepared by a hydrolysis method at 323 K, and characterized by X-ray diffraction (XRD), Brunauer-Emmett-Teller (BET), ultraviolet-visible diffuse reflection spectroscopy (UV-Vis DRS), infrared spectroscopy (IR) and photoelectrochemical (PEC). The ultraviolet (UV) and visible light photocatalytic activities of as-prepared rutile and anatase TiO2 nano-photocatalysts with almost same specific surface areas were evaluated by methyl orange (MO) as mode compound to photocatalytic reaction. The results of the photocatalytic experiment shows that when rutile and anatase have the similar specific surface area of approximately 95 m2.g-1, the UV light photocatalytic activity of rutile is comparable to that of anatase, while rutile shows significantly higher visible light photocatalytic activities than anatase. The photoelectrochemical experiment shows that the order of photocurrent densities of the catalysts from weak to strong is in accordance with the order of UV light photocatalytic activities of the catalysts from low to high under UV light irradiation.

16.
PLoS One ; 8(2): e56157, 2013.
Artigo em Inglês | MEDLINE | ID: mdl-23409145

RESUMO

An ability to forecast the prevalence of specific subtypes of avian influenza viruses (AIV) in live-bird markets would facilitate greatly the implementation of preventative measures designed to minimize poultry losses and human exposure. The minimum requirement for developing predictive quantitative tools is surveillance data of AIV prevalence sampled frequently over several years. Recently, a 4-year time series of monthly sampling of hemagglutinin subtypes 1-13 in ducks, chickens and quail in live-bird markets in southern China has become available. We used these data to investigate whether a simple statistical model, based solely on historical data (variables such as the number of positive samples in host X of subtype Y time t months ago), could accurately predict prevalence of H5 and H9 subtypes in chickens. We also examined the role of ducks and quail in predicting prevalence in chickens within the market setting because between-species transmission is thought to occur within markets but has not been measured. Our best statistical models performed remarkably well at predicting future prevalence (pseudo-R(2) = 0.57 for H9 and 0.49 for H5), especially considering the multi-host, multi-subtype nature of AIVs. We did not find prevalence of H5/H9 in ducks or quail to be predictors of prevalence in chickens within the Chinese markets. Our results suggest surveillance protocols that could enable more accurate and timely predictive statistical models. We also discuss which data should be collected to allow the development of mechanistic models.


Assuntos
Aves/virologia , Vírus da Influenza A/fisiologia , Influenza Aviária/epidemiologia , Modelos Estatísticos , Animais , Monitoramento Epidemiológico/veterinária , Influenza Aviária/virologia , Prevalência , Análise de Regressão
17.
Influenza Other Respir Viruses ; 7(1): 97-107, 2013 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-22458429

RESUMO

BACKGROUND: Avian influenza viruses (AIV) cause huge economic losses in poultry industries and pose a substantial threat to human health. However, predicting AIV epizootics and emergence in humans is confounded by insufficient empirical data on the ecology and dynamics of AIV in poultry systems. To address this gap, we quantified incidence patterns for 13 hemagglutinin subtypes of AIV using 6 years of surveillance data that were collected from ten different species of poultry and three different types of poultry holdings (contexts) - retail, wholesale, or farms. METHODS: We collected 42 646 samples in Shantou, China between 2000 and 2006. We screened samples for hemagglutinin subtypes 1-13 of AIV and Avian Paramyxovirus-type-1 (APMV-1) using monospecific antisera in hemagglutination inhibition tests. We analyzed the data to determine seasonality patterns, subtype-host, and subtype-subtype interactions as well as subtype bias in incidence in different contexts. RESULTS: H3, H6, H9, and APMV-1 were the most prevalent. No significant seasonality was found when all subtypes were considered together. For most AIV subtypes and APMV-1, there was subtype specificity for host, context, and coinfection partner. H5 showed the most generalized host usage pattern, followed by H9 and H6. CONCLUSION: Subtype-specific patterns because of host, context, and other subtypes suggest that risk assessments that exclude these details are likely inaccurate. Surveillance should include longitudinal sampling of multiple host species in multiple contexts. Quantitative models of control strategies must consider multiple subtypes, hosts, and source contexts to assess the effectiveness of interventions.


Assuntos
Glicoproteínas de Hemaglutininação de Vírus da Influenza/genética , Vírus da Influenza A/genética , Influenza Aviária/transmissão , Doenças das Aves Domésticas/transmissão , Aves Domésticas/virologia , Animais , Galinhas/virologia , China/epidemiologia , Surtos de Doenças , Patos/virologia , Testes de Inibição da Hemaglutinação , Glicoproteínas de Hemaglutininação de Vírus da Influenza/classificação , Especificidade de Hospedeiro , Humanos , Incidência , Vírus da Influenza A/classificação , Vírus da Influenza A/isolamento & purificação , Influenza Aviária/epidemiologia , Influenza Aviária/virologia , Doenças das Aves Domésticas/epidemiologia , Doenças das Aves Domésticas/virologia , Prevalência , Especificidade da Espécie
18.
J Virol ; 86(11): 6075-83, 2012 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-22438558

RESUMO

Domestic ducks in southern China act as an important reservoir for influenza viruses and have also facilitated the establishment of multiple H6 influenza virus lineages. To understand the continuing evolution of these established lineages, 297 H6 viruses isolated from domestic ducks during 2006 and 2007 were genetically and antigenically analyzed. Phylogenetic analyses showed that group II duck H6 viruses had replaced the previously predominant group I lineage and extended their geographic distribution from coastal to inland regions. Group II H6 virus showed that the genesis and development of multiple types of deletions in the neuraminidase (NA) stalk region could occur in the influenza viruses from domestic ducks. A gradual replacement of the N2 NA subtype with N6 was observed. Significant antigenic changes occurred within group II H6 viruses so that they became antigenically distinguishable from group I and gene pool viruses. Gene exchange between group II H6 viruses and the established H5N1, H9N2, or H6N1 virus lineages in poultry in the region was very limited. These findings suggest that domestic ducks can facilitate significant genetic and antigenic changes in viruses established in this host and highlight gaps in our knowledge of influenza virus ecology and even the evolutionary behavior of this virus family in its aquatic avian reservoirs.


Assuntos
Vírus da Influenza A/classificação , Vírus da Influenza A/isolamento & purificação , Influenza Aviária/epidemiologia , Influenza Aviária/virologia , Animais , Antígenos Virais/análise , China/epidemiologia , Patos , Vírus da Influenza A/genética , Vírus da Influenza A/imunologia , Epidemiologia Molecular , Dados de Sequência Molecular , Neuraminidase/genética , Neuraminidase/imunologia , Filogenia , RNA Viral/genética , Recombinação Genética , Análise de Sequência de DNA , Deleção de Sequência , Proteínas Virais/genética , Proteínas Virais/imunologia
19.
Ai Zheng ; 24(6): 735-9, 2005 Jun.
Artigo em Chinês | MEDLINE | ID: mdl-15946491

RESUMO

BACKGROUND & OBJECTIVE: Breast cancer may undergo metastasis in early phase. Distant metastasis, especially bone metastasis, may influence prognosis of breast cancer patients. Bone marrow micrometastasis (BMM) is difficult to detect with routine methods. This study was designed to evaluate expression and clinical significance of cytokeratin 19 (CK19) in bone marrow of patients with breast cancer. METHODS: Expression of CK19 mRNA in bone marrows of 65 breast cancer patients, 15 benign breast disease patients, and 8 healthy volunteers was detected by reverse transcription-polymerase chain reaction (RT-PCR). Correlation of CK19 mRNA expression to clinicopathologic features of the 65 breast cancer patients was analyzed. RESULTS: Positive rate of CK19 mRNA was 33.8% in the 65 breast cancer patients, and 0 in both benign breast disease patients and healthy volunteers. Expression of CK19 mRNA was positively correlated with tumor size and clinical stage (P < 0.05), but was not related to age and lymph node status (P > 0.05). In addition, positive rate of CK19 mRNA was positively correlated with carcinoembryonic antigen (CEA) in peripheral blood (r=0.372, P=0.002). CONCLUSIONS: CK19 mRNA may be used as a molecular marker to detect bone marrow micrometastasis in patients with breast cancer. The detection may help to select proper therapy and predict prognosis of breast cancer patients.


Assuntos
Medula Óssea/metabolismo , Neoplasias da Mama/metabolismo , Carcinoma Ductal de Mama/metabolismo , Queratina-19/biossíntese , Adulto , Idoso , Neoplasias da Mama/patologia , Neoplasias da Mama Masculina/metabolismo , Neoplasias da Mama Masculina/patologia , Antígeno Carcinoembrionário/sangue , Carcinoma Ductal de Mama/patologia , Feminino , Fibroadenoma/sangue , Fibroadenoma/metabolismo , Fibroadenoma/patologia , Humanos , Queratina-19/genética , Metástase Linfática , Masculino , Pessoa de Meia-Idade , Estadiamento de Neoplasias , RNA Mensageiro/biossíntese , RNA Mensageiro/genética
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