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1.
Nature ; 633(8030): 537-541, 2024 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-39294348

RESUMO

When sustained for megayears (refs. 1,2), high-power jets from supermassive black holes (SMBHs) become the largest galaxy-made structures in the Universe3. By pumping electrons, atomic nuclei and magnetic fields into the intergalactic medium (IGM), these energetic flows affect the distribution of matter and magnetism in the cosmic web4-6 and could have a sweeping cosmological influence if they reached far at early epochs. For the past 50 years, the known size range of black hole jet pairs ended at 4.6-5.0 Mpc (refs. 7-9), or 20-30% of a cosmic void radius in the Local Universe10. An observational lack of longer jets, as well as theoretical results11, thus suggested a growth limit at about 5 Mpc (ref. 12). Here we report observations of a radio structure spanning about 7 Mpc, or roughly 66% of a coeval cosmic void radius, apparently generated by a black hole between 4.4 - 0.7 + 0.2 and 6.3 Gyr after the Big Bang. The structure consists of a northern lobe, a northern jet, a core, a southern jet with an inner hotspot and a southern outer hotspot with a backflow. This system demonstrates that jets can avoid destruction by magnetohydrodynamical instabilities over cosmological distances, even at epochs when the Universe was 7 to 1 5 - 2 + 6 times denser than it is today. How jets can retain such long-lived coherence is unknown at present.

2.
Nature ; 617(7961): 477-482, 2023 05.
Artigo em Inglês | MEDLINE | ID: mdl-37198310

RESUMO

Type Ia supernovae (SNe Ia) are thermonuclear explosions of degenerate white dwarf stars destabilized by mass accretion from a companion star1, but the nature of their progenitors remains poorly understood. A way to discriminate between progenitor systems is through radio observations; a non-degenerate companion star is expected to lose material through winds2 or binary interaction3 before explosion, and the supernova ejecta crashing into this nearby circumstellar material should result in radio synchrotron emission. However, despite extensive efforts, no type Ia supernova (SN Ia) has ever been detected at radio wavelengths, which suggests a clean environment and a companion star that is itself a degenerate white dwarf star4,5. Here we report on the study of SN 2020eyj, a SN Ia showing helium-rich circumstellar material, as demonstrated by its spectral features, infrared emission and, for the first time in a SN Ia to our knowledge, a radio counterpart. On the basis of our modelling, we conclude that the circumstellar material probably originates from a single-degenerate binary system in which a white dwarf accretes material from a helium donor star, an often proposed formation channel for SNe Ia (refs. 6,7). We describe how comprehensive radio follow-up of SN 2020eyj-like SNe Ia can improve the constraints on their progenitor systems.

3.
J Infect Dis ; 2024 Mar 13.
Artigo em Inglês | MEDLINE | ID: mdl-38478746

RESUMO

In the recent mpox outbreak, people living with HIV (PLWH) were at high risk both for contracting infection and for suffering a more severe disease course. We studied cellular and humoral immune responses elicited by mpox infection (n = 5; n = 3 PLWH) or smallpox vaccination (n = 17; all PLWH) in a cohort of men who have sex with men. All PLWH were successfully treated, with stable CD4 counts and undetectable HIV viral loads. 11/17 vaccinated individuals had received childhood smallpox vaccination. In this group of individuals, both two-dose MVA-vaccination and natural infection evoked mpox-specific immune responses mediated by B cells as well as CD4 and CD8 T cells. This study improves our understanding of smallpox vaccination mediated cross-reactivity to other orthopox viruses, and the long-lasting durability of childhood smallpox vaccination mediated immune responses including in PLWH.

4.
PLoS Pathog ; 18(3): e1010406, 2022 03.
Artigo em Inglês | MEDLINE | ID: mdl-35294506

RESUMO

Gram-positive bacteria are protected by a thick mesh of peptidoglycan (PG) completely engulfing their cells. This PG network is the main component of the bacterial cell wall, it provides rigidity and acts as foundation for the attachment of other surface molecules. Biosynthesis of PG consumes a high amount of cellular resources and therefore requires careful adjustments to environmental conditions. An important switch in the control of PG biosynthesis of Listeria monocytogenes, a Gram-positive pathogen with a high infection fatality rate, is the serine/threonine protein kinase PrkA. A key substrate of this kinase is the small cytosolic protein ReoM. We have shown previously that ReoM phosphorylation regulates PG formation through control of MurA stability. MurA catalyzes the first step in PG biosynthesis and the current model suggests that phosphorylated ReoM prevents MurA degradation by the ClpCP protease. In contrast, conditions leading to ReoM dephosphorylation stimulate MurA degradation. How ReoM controls degradation of MurA and potential other substrates is not understood. Also, the individual contribution of the ~20 other known PrkA targets to PG biosynthesis regulation is unknown. We here present murA mutants which escape proteolytic degradation. The release of MurA from ClpCP-dependent proteolysis was able to activate PG biosynthesis and further enhanced the intrinsic cephalosporin resistance of L. monocytogenes. This latter effect required the RodA3/PBP B3 transglycosylase/transpeptidase pair. One murA escape mutation not only fully rescued an otherwise non-viable prkA mutant during growth in batch culture and inside macrophages but also overcompensated cephalosporin hypersensitivity. Our data collectively indicate that the main purpose of PrkA-mediated signaling in L. monocytogenes is control of MurA stability during standard laboratory growth conditions and intracellular growth in macrophages. These findings have important implications for the understanding of PG biosynthesis regulation and ß-lactam resistance of L. monocytogenes and related Gram-positive bacteria.


Assuntos
Listeria monocytogenes , Peptidoglicano , Parede Celular/metabolismo , Listeria monocytogenes/genética , Listeria monocytogenes/metabolismo , Mutação , Peptidoglicano/metabolismo , Proteínas Serina-Treonina Quinases/genética
5.
Int J Med Microbiol ; 314: 151607, 2024 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-38367508

RESUMO

Measles is a highly contagious airborne viral disease. It can lead to serious complications and death and is preventable by vaccination. The live-attenuated measles vaccine (LAMV) derived from a measles virus (MV) isolated in 1954 has been in use globally for six decades and protects effectively by providing a durable humoral and cell-mediated immunity. Our study addresses the temporal stability of epitopes on the viral surface glycoprotein hemagglutinin (H) which is the major target of MV-neutralizing antibodies. We investigated the binding of seven vaccine-induced MV-H-specific monoclonal antibodies (mAbs) to cell-free synthesized MV-H proteins derived from the H gene sequences obtained from a lung specimen of a fatal case of measles pneumonia in 1912 and an isolate from a current case. The binding of four out of seven mAbs to the H protein of both MV strains provides evidence of epitopes that are stable for more than 100 years. The binding of the universally neutralizing mAbs RKI-MV-12b and RKI-MV-34c to the H protein of the 1912 MV suggests the long-term stability of highly conserved epitopes on the MV surface.


Assuntos
Vírus do Sarampo , Sarampo , Humanos , Vírus do Sarampo/genética , Anticorpos Neutralizantes , Testes de Neutralização , Vacina contra Sarampo/genética , Sarampo/prevenção & controle , Anticorpos Antivirais , Epitopos/genética , Hemaglutininas Virais/genética , Anticorpos Monoclonais
6.
BMC Infect Dis ; 24(1): 1153, 2024 Oct 14.
Artigo em Inglês | MEDLINE | ID: mdl-39396951

RESUMO

INTRODUCTION: During the mpox outbreak in 2022, the highest number of cases in Germany were registered in Berlin, almost all of them in men who have sex with men (MSM). However, the frequency of clinically undiagnosed infections is unknown. METHODS: A cross-sectional study was conducted among MSM in Berlin, Germany. Participants were recruited from private practices and community-based checkpoints specialised in HIV and STI care for MSM. They were asked to complete an online questionnaire on socio-demographic data, mpox diagnosis, vaccination history and sexual behaviour, and to provide a blood sample for serological analysis. The samples were tested for antibodies against a range of antigens to distinguish between antibodies induced by mpox infection and MVA vaccination, with pre-immune sera from childhood smallpox vaccination as a confounding factor. Associations of behavioural variables with reported and suspected mpox diagnosis as the outcome were tested using univariable and multivariable logistic regression models. RESULTS: Between the 11th April and 1st July 2023, 1,119 participants were recruited in eight private practices and two community-based checkpoints in Berlin. All participants provided a blood sample for serological testing. Information for the online questionnaire was provided by 728 participants; core data on age and mpox history for participants who did not provide questionnaire data were provided by the practices for an additional 218 participants. A previous diagnosis of mpox was reported for/by 70 participants (7.4%). Using a conservative and strict case definition, we serologically identified an additional 91 individuals with suspected undiagnosed mpox infection. Individuals with reported or suspected mpox infections reported more condomless anal sex partners in the past 3 months (OR = 5.93; 95% CI 2.10-18.35 for 5-10 partners; OR = 9.53; 95% CI 2.72-37.54 for > 10 partners) and were more likely to report sexual contact with partners diagnosed with mpox (OR = 2.87; 95% CI 1.39-5.84). CONCLUSION: A substantial proportion of mpox infections were clinically undiagnosed. The number of condomless anal sex partners was strongly associated with both confirmed and suspected undiagnosed mpox infection. Therefore, mpox control measures based on clinical diagnosis of mpox are likely to have limited effectiveness in preventing mpox transmission in outbreak situations because many infections remain unrecognised and undiagnosed.


Assuntos
Homossexualidade Masculina , Humanos , Masculino , Adulto , Homossexualidade Masculina/estatística & dados numéricos , Estudos Transversais , Estudos Soroepidemiológicos , Berlim/epidemiologia , Adulto Jovem , Pessoa de Meia-Idade , Comportamento Sexual/estatística & dados numéricos , Inquéritos e Questionários , Alemanha/epidemiologia , Adolescente , Doenças não Diagnosticadas/epidemiologia , Anticorpos Antivirais/sangue
7.
Nature ; 553(7689): 473-476, 2018 01 25.
Artigo em Inglês | MEDLINE | ID: mdl-29211709

RESUMO

Quasars are the most luminous non-transient objects known and as a result they enable studies of the Universe at the earliest cosmic epochs. Despite extensive efforts, however, the quasar ULAS J1120 + 0641 at redshift z = 7.09 has remained the only one known at z > 7 for more than half a decade. Here we report observations of the quasar ULAS J134208.10 + 092838.61 (hereafter J1342 + 0928) at redshift z = 7.54. This quasar has a bolometric luminosity of 4 × 1013 times the luminosity of the Sun and a black-hole mass of 8 × 108 solar masses. The existence of this supermassive black hole when the Universe was only 690 million years old-just five per cent of its current age-reinforces models of early black-hole growth that allow black holes with initial masses of more than about 104 solar masses or episodic hyper-Eddington accretion. We see strong evidence of absorption of the spectrum of the quasar redwards of the Lyman α emission line (the Gunn-Peterson damping wing), as would be expected if a significant amount (more than 10 per cent) of the hydrogen in the intergalactic medium surrounding J1342 + 0928 is neutral. We derive such a significant fraction of neutral hydrogen, although the exact fraction depends on the modelling. However, even in our most conservative analysis we find a fraction of more than 0.33 (0.11) at 68 per cent (95 per cent) probability, indicating that we are probing well within the reionization epoch of the Universe.

8.
J Med Virol ; 95(12): e29261, 2023 12.
Artigo em Inglês | MEDLINE | ID: mdl-38054557

RESUMO

The monkeypox virus (MPXV) outbreak in 2022 has renewed interest in the detection of antibodies against orthopox viruses (OPXV) and MPXV, as serological methods can aid diagnostics and are key to epidemiological studies. Here three complementary serological methods are described with different strengths to aid the development and evaluation of in-house assays: An immunofluorescence assay (IFA) for specific detection of IgG and IgM, an enzyme-linked immunosorbent assay for higher sample throughput to aid epidemiological studies and a neutralization test to detect virus neutralizing antibodies. As implementation of MPXV-specific diagnostics is often hampered by the requirement for a dedicated biosafety level 3 laboratory (BSL-3), the focus of this study is on biosafety aspects to facilitate safe testing also under BSL-2 conditions. To this aim, it was analyzed whether OPXV, which can be handled under BSL-2 conditions, could be used as less virulent alternatives to MPXV. Furthermore, an inactivation method was established to remove up to five log-steps of infectious virus particles from viraemic sera without compromising antibody detection. The results show that immunological cross-reactivity between OPXV provides an opportunity for the interchangeable usage of different OPXV species in serological assays, enabling MPXV serology outside of BSL-3 facilities.


Assuntos
Contenção de Riscos Biológicos , Monkeypox virus , Humanos , Laboratórios , Anticorpos Antivirais , Testes de Neutralização
9.
Infection ; 51(4): 1093-1102, 2023 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-36913112

RESUMO

PURPOSE: COViK, a prospective hospital-based multicenter case-control study in Germany, aims to assess the effectiveness of COVID-19 vaccines against severe disease. Here, we report vaccine effectiveness (VE) against COVID-19-caused hospitalization and intensive care treatment during the Omicron wave. METHODS: We analyzed data from 276 cases with COVID-19 and 494 control patients recruited in 13 hospitals from 1 December 2021 to 5 September 2022. We calculated crude and confounder-adjusted VE estimates. RESULTS: 21% of cases (57/276) were not vaccinated, compared to 5% of controls (26/494; p < 0.001). Confounder-adjusted VE against COVID-19-caused hospitalization was 55.4% (95% CI: 12-78%), 81.5% (95% CI: 68-90%) and 95.6% (95%CI: 88-99%) after two, three and four vaccine doses, respectively. VE against hospitalization due to COVID-19 remained stable up to one year after three vaccine doses. CONCLUSION: Three vaccine doses remained highly effective in preventing severe disease and this protection was sustained; a fourth dose further increased protection.


Assuntos
COVID-19 , Humanos , COVID-19/epidemiologia , COVID-19/prevenção & controle , Vacinas contra COVID-19 , Estudos de Casos e Controles , Estudos Prospectivos , Eficácia de Vacinas , Alemanha/epidemiologia
10.
Nature ; 518(7537): 74-6, 2015 Feb 05.
Artigo em Inglês | MEDLINE | ID: mdl-25561176

RESUMO

Quasars have long been known to be variable sources at all wavelengths. Their optical variability is stochastic and can be due to a variety of physical mechanisms; it is also well-described statistically in terms of a damped random walk model. The recent availability of large collections of astronomical time series of flux measurements (light curves) offers new data sets for a systematic exploration of quasar variability. Here we report the detection of a strong, smooth periodic signal in the optical variability of the quasar PG 1302-102 with a mean observed period of 1,884 ± 88 days. It was identified in a search for periodic variability in a data set of light curves for 247,000 known, spectroscopically confirmed quasars with a temporal baseline of about 9 years. Although the interpretation of this phenomenon is still uncertain, the most plausible mechanisms involve a binary system of two supermassive black holes with a subparsec separation. Such systems are an expected consequence of galaxy mergers and can provide important constraints on models of galaxy formation and evolution.

11.
Nature ; 520(7549): 646-9, 2015 Apr 30.
Artigo em Inglês | MEDLINE | ID: mdl-25925477

RESUMO

The Galactic Centre hosts a puzzling stellar population in its inner few parsecs, with a high abundance of surprisingly young, relatively massive stars bound within the deep potential well of the central supermassive black hole, Sagittarius A* (ref. 1). Previous studies suggest that the population of objects emitting soft X-rays (less than 10 kiloelectronvolts) within the surrounding hundreds of parsecs, as well as the population responsible for unresolved X-ray emission extending along the Galactic plane, is dominated by accreting white dwarf systems. Observations of diffuse hard-X-ray (more than 10 kiloelectronvolts) emission in the inner 10 parsecs, however, have been hampered by the limited spatial resolution of previous instruments. Here we report the presence of a distinct hard-X-ray component within the central 4 × 8 parsecs, as revealed by subarcminute-resolution images in the 20-40 kiloelectronvolt range. This emission is more sharply peaked towards the Galactic Centre than is the surface brightness of the soft-X-ray population. This could indicate a significantly more massive population of accreting white dwarfs, large populations of low-mass X-ray binaries or millisecond pulsars, or particle outflows interacting with the surrounding radiation field, dense molecular material or magnetic fields. However, all these interpretations pose significant challenges to our understanding of stellar evolution, binary formation, and cosmic-ray production in the Galactic Centre.

12.
Artigo em Alemão | MEDLINE | ID: mdl-33856510

RESUMO

The collection of data on SARS-CoV­2 tests is central to the assessment of the infection rate in the context of the COVID-19 pandemic. At the Robert Koch Institute (RKI), data collected from various laboratory data recording systems are consolidated. First, this article aims to exemplify significant aspects regarding test procedures. Subsequently the different systems for recording laboratory tests are described and test numbers from the RKI test laboratory query and the laboratory-based SARS-CoV­2 surveillance as well as accounting data from the Association of Statutory Health Insurance Physicians for SARS-CoV­2 laboratory tests are shown.Early in the pandemic, the RKI test laboratory query and the laboratory-based SARS-CoV­2 surveillance became available and able to evaluate data on performed tests and test capacities. By recording the positive and negative test results, statements about the total number of tests and the proportion of positive test rates can be made. While the aggregate test numbers are largely representative nationwide, they are not always representative at the state and district level. The billing data of the Association of Statutory Health Insurance Physicians can complement the laboratory data afterwards. In addition, it can provide a retrospective assessment of the total number of SARS-CoV­2 numbers in Germany, because the services provided by statutory health insurers (around 85% of the population in Germany) are included. The various laboratory data recording systems complement one another and the evaluations flow into the recommended measures for the pandemic response.


Assuntos
COVID-19 , Pandemias , Teste para COVID-19 , Alemanha/epidemiologia , Humanos , Estudos Retrospectivos , SARS-CoV-2
13.
BMC Biotechnol ; 20(1): 53, 2020 10 06.
Artigo em Inglês | MEDLINE | ID: mdl-33023547

RESUMO

BACKGROUND: Few bead-based multiplex assays have been described that detect antibodies against the protozoan parasite Toxoplasma gondii in large-scale seroepidemiological surveys. Moreover, each multiplex assay has specific variations or limitations, such as the use of truncated or fusion proteins as antigens, potentially masking important epitopes. Consequently, such an assay must be developed by interested groups as none is commercially available. RESULTS: We report the bacterial expression and use of N-terminal fusion-free, soluble, in vivo biotinylated recombinant surface antigens SAG1 and SAG2A for the detection of anti-T. gondii IgG antibodies. The expression system relies on three compatible plasmids. An expression construct produces a fusion of maltose-binding protein with SAG1 (or SAG2A), separated by a TEV protease cleavage site, followed by a peptide sequence recognized by E. coli biotin ligase BirA (AviTag), and a terminal six histidine tag for affinity purification. TEV protease and BirA are encoded on a second plasmid, and their expression leads to proteolytic cleavage of the fusion protein and a single biotinylated lysine within the AviTag by BirA. Correct folding of the parasite proteins is dependent on proper disulfide bonding, which is facilitated by a sulfhydryl oxidase and a protein disulfide isomerase, encoded on the third plasmid. The C-terminal biotinylation allowed the oriented, reproducible coupling of the purified surface antigens to magnetic Luminex beads, requiring only minute amounts of protein per determination. We showed that an N-terminal fusion partner such as maltose-binding protein negatively influenced antibody binding, confirming that access to SAG1's N-terminal epitopes is important for antibody recognition. We validated our bead-based multiplex assay with human sera previously tested with commercial diagnostic assays and found concordance of 98-100% regarding both, sensitivity and specificity, even when only biotinylated SAG1 was used as antigen. CONCLUSIONS: Our recombinant in vivo-biotinylated T. gondii antigens offer distinct advantages compared to previously described proteins used in multiplex serological assays for T. gondii. They offer a cheap, specific and sensitive alternative to either parasite lysates or eukaryotic-cell expressed SAG1/SAG2A for BBMA and other formats. The described general expression strategy can also be used for other antigens where oriented immobilization is key for sensitive recognition by antibodies and ligands.


Assuntos
Antígenos de Protozoários/genética , Glicoproteínas de Membrana/genética , Proteínas de Protozoários/genética , Toxoplasma/genética , Toxoplasma/imunologia , Animais , Anticorpos Antiprotozoários/sangue , Anticorpos Antiprotozoários/imunologia , Antígenos de Protozoários/química , Antígenos de Protozoários/imunologia , Biotinilação , Carbono-Nitrogênio Ligases , Ensaio de Imunoadsorção Enzimática , Escherichia coli/genética , Proteínas de Escherichia coli , Regulação Bacteriana da Expressão Gênica , Humanos , Imunoglobulina G , Glicoproteínas de Membrana/química , Proteínas de Protozoários/química , Proteínas de Protozoários/imunologia , Proteínas Recombinantes/genética , Proteínas Recombinantes/imunologia , Proteínas Repressoras , Análise de Sequência , Estudos Soroepidemiológicos , Toxoplasmose/diagnóstico
14.
PLoS Pathog ; 14(5): e1007048, 2018 05.
Artigo em Inglês | MEDLINE | ID: mdl-29718991

RESUMO

The exceptional toxicity of botulinum neurotoxins (BoNTs) is mediated by high avidity binding to complex polysialogangliosides and intraluminal segments of synaptic vesicle proteins embedded in the presynaptic membrane. One peculiarity is an exposed hydrophobic loop in the toxin's cell binding domain HC, which is located between the ganglioside- and protein receptor-binding sites, and that is particularly pronounced in the serotypes BoNT/B, DC, and G sharing synaptotagmin as protein receptor. Here, we provide evidence that this HC loop is a critical component of their tripartite receptor recognition complex. Binding to nanodisc-embedded receptors and toxicity were virtually abolished in BoNT mutants lacking residues at the tip of the HC loop. Surface plasmon resonance experiments revealed that only insertion of the HC loop into the lipid-bilayer compensates for the entropic penalty inflicted by the dual-receptor binding. Our results represent a new paradigm of how BoNT/B, DC, and G employ ternary interactions with a protein, ganglioside, and lipids to mediate their extraordinary neurotoxicity.


Assuntos
Toxinas Botulínicas/genética , Toxinas Botulínicas/metabolismo , Animais , Sítios de Ligação , Toxinas Botulínicas Tipo A/metabolismo , Proteínas de Transporte/metabolismo , Membrana Celular/metabolismo , Cristalografia por Raios X , Gangliosídeos , Interações Hidrofóbicas e Hidrofílicas , Lipídeos , Glicoproteínas de Membrana/metabolismo , Camundongos , Ligação Proteica , Conformação Proteica , Receptores de Neurotransmissores/metabolismo , Sorogrupo , Vesículas Sinápticas
15.
Eur Arch Otorhinolaryngol ; 277(11): 3051-3057, 2020 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-32623506

RESUMO

PURPOSE: The purpose of this study was to describe the microbiology of recurrent acute exacerbations of chronic rhinosinusitis over time. METHODS: Retrospective review of patients with recurrent acute exacerbations of chronic rhinosinusitis who underwent endoscopic-guided cultures during acute exacerbations of chronic rhinosinusitis. RESULTS: 386 cultures were obtained from 112 patients during recurrent acute exacerbations of CRS. A change of bacterial isolates during the course of recurrent exacerbations was observed in 68% (76/112) of patients, necessitating a change of treatment in 40% (45/112). The main risk factor for the subsequent change in cultures was polymicrobial growth. Sinus surgery was not associated with subsequent change in cultured isolates. Resistant strains developed in 11.6% (13/112) of patients, of whom those with abnormal mucociliary clearance being at the highest risk. CONCLUSION: Repeated middle meatal cultures should be considered in patients with recurrent exacerbations of CRS, particularly in cases not responding to standard therapy.


Assuntos
Bacteriologia , Rinite , Sinusite , Doença Crônica , Endoscopia , Humanos , Estudos Retrospectivos
16.
Anal Chem ; 91(17): 11215-11222, 2019 09 03.
Artigo em Inglês | MEDLINE | ID: mdl-31401830

RESUMO

Toxoplasmosis, while often an asymptomatic parasitic disease in healthy individuals, can cause severe complications in immunocompromised persons and during pregnancy. The most common method to diagnose Toxoplasma gondii infections is the serological determination of antibodies directed against parasite protein antigens. Here we report the use of a bead-based multiplex assay containing a synthetic phosphoglycan portion of the Toxoplasma gondii glycosylphosphatidylinositol (GPI1) for the detection of GPI1-specific antibodies in human sera. The glycan was conjugated to beads at the lipid site to retain its natural orientation and its immunogenic groups. We compared the response against GPI1 with that against the protein antigen SAG1, a common component of commercial serological assays, via the detection of parasite-specific human IgG and IgM antibodies, respectively. The GPI1-based test is in excellent agreement with the results for the commercial ELISA, as the ROC analysis of the GPI1 test shows 97% specificity and 98% sensitivity for the assay. GPI1 was a more reliable predictor for a parasite-specific IgM response compared to SAG1, indicating that a bead-based multiplex assay using GPI1 in combination with SAG1 may strengthen Toxoplasma gondii serology, in particular in seroepidemiological studies.


Assuntos
Anticorpos Antiprotozoários/sangue , Glicosilfosfatidilinositóis/química , Polissacarídeos/química , Toxoplasma/química , Anticorpos Antiprotozoários/imunologia , Especificidade de Anticorpos , Antígenos de Protozoários/sangue , Antígenos de Protozoários/imunologia , Ensaio de Imunoadsorção Enzimática , Glicosilfosfatidilinositóis/imunologia , Humanos , Polissacarídeos/imunologia , Curva ROC , Toxoplasma/imunologia , Toxoplasmose/sangue , Toxoplasmose/imunologia
18.
Nature ; 494(7438): 449-51, 2013 Feb 28.
Artigo em Inglês | MEDLINE | ID: mdl-23446416

RESUMO

Broad X-ray emission lines from neutral and partially ionized iron observed in active galaxies have been interpreted as fluorescence produced by the reflection of hard X-rays off the inner edge of an accretion disk. In this model, line broadening and distortion result from rapid rotation and relativistic effects near the black hole, the line shape being sensitive to its spin. Alternative models in which the distortions result from absorption by intervening structures provide an equally good description of the data, and there has been no general agreement on which is correct. Recent claims that the black hole (2 × 10(6) solar masses) at the centre of the galaxy NGC 1365 is rotating at close to its maximum possible speed rest on the assumption of relativistic reflection. Here we report X-ray observations of NGC 1365 that reveal the relativistic disk features through broadened Fe-line emission and an associated Compton scattering excess of 10-30 kiloelectronvolts. Using temporal and spectral analyses, we disentangle continuum changes due to time-variable absorption from reflection, which we find arises from a region within 2.5 gravitational radii of the rapidly spinning black hole. Absorption-dominated models that do not include relativistic disk reflection can be ruled out both statistically and on physical grounds.

19.
Nature ; 490(7421): 514-6, 2012 Oct 25.
Artigo em Inglês | MEDLINE | ID: mdl-23099405

RESUMO

Unresolved anisotropies of the cosmic near-infrared background radiation are expected to have contributions from the earliest galaxies during the epoch of reionization and from faint, dwarf galaxies at intermediate redshifts. Previous measurements were unable to pinpoint conclusively the dominant origin because they did not sample spatial scales that were sufficiently large to distinguish between these two possibilities. Here we report a measurement of the anisotropy power spectrum from subarcminute to one-degree angular scales, and find the clustering amplitude to be larger than predicted by the models based on the two existing explanations. As the shot-noise level of the power spectrum is consistent with that expected from faint galaxies, a new source population on the sky is not necessary to explain the observations. However, a physical mechanism that increases the clustering amplitude is needed. Motivated by recent results related to the extended stellar light profile in dark-matter haloes, we consider the possibility that the fluctuations originate from intrahalo stars of all galaxies. We find that the measured power spectrum can be explained by an intrahalo light fraction of 0.07 to 0.2 per cent relative to the total luminosity in dark-matter haloes of 10(9) to 10(12) solar masses at redshifts of about 1 to 4.

20.
Nature ; 486(7402): 233-6, 2012 Jun 13.
Artigo em Inglês | MEDLINE | ID: mdl-22699613

RESUMO

The Hubble Deep Field provides one of the deepest multiwavelength views of the distant Universe and has led to the detection of thousands of galaxies seen throughout cosmic time. An early map of the Hubble Deep Field at a wavelength of 850 micrometres, which is sensitive to dust emission powered by star formation, revealed the brightest source in the field, dubbed HDF 850.1 (ref. 2). For more than a decade, and despite significant efforts, no counterpart was found at shorter wavelengths, and it was not possible to determine its redshift, size or mass. Here we report a redshift of z = 5.183 for HDF 850.1, from a millimetre-wave molecular line scan. This places HDF 850.1 in a galaxy overdensity at z ≈ 5.2, corresponding to a cosmic age of only 1.1 billion years after the Big Bang. This redshift is significantly higher than earlier estimates and higher than those of most of the hundreds of submillimetre-bright galaxies identified so far. The source has a star-formation rate of 850 solar masses per year and is spatially resolved on scales of 5 kiloparsecs, with an implied dynamical mass of about 1.3 × 10(11) solar masses, a significant fraction of which is present in the form of molecular gas. Despite our accurate determination of redshift and position, a counterpart emitting starlight remains elusive.

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