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1.
Nature ; 555(7696): 342-345, 2018 03 15.
Artigo em Inglês | MEDLINE | ID: mdl-29334685

RESUMO

The modern theory of charge polarization in solids is based on a generalization of Berry's phase. The possibility of the quantization of this phase arising from parallel transport in momentum space is essential to our understanding of systems with topological band structures. Although based on the concept of charge polarization, this same theory can also be used to characterize the Bloch bands of neutral bosonic systems such as photonic or phononic crystals. The theory of this quantized polarization has recently been extended from the dipole moment to higher multipole moments. In particular, a two-dimensional quantized quadrupole insulator is predicted to have gapped yet topological one-dimensional edge modes, which stabilize zero-dimensional in-gap corner states. However, such a state of matter has not previously been observed experimentally. Here we report measurements of a phononic quadrupole topological insulator. We experimentally characterize the bulk, edge and corner physics of a mechanical metamaterial (a material with tailored mechanical properties) and find the predicted gapped edge and in-gap corner states. We corroborate our findings by comparing the mechanical properties of a topologically non-trivial system to samples in other phases that are predicted by the quadrupole theory. These topological corner states are an important stepping stone to the experimental realization of topologically protected wave guides in higher dimensions, and thereby open up a new path for the design of metamaterials.

2.
Anaesthesia ; 2024 Apr 12.
Artigo em Inglês | MEDLINE | ID: mdl-38607309

RESUMO

BACKGROUND: Anaemia following major surgery may be associated with unplanned readmission to hospital. However, the severity-response relationship between the degree of anaemia at discharge and the risk of unplanned readmission is poorly defined. We aimed to describe the severity-response relationship between haemoglobin concentration at the time of discharge and the risk of unplanned readmission in a cohort of patients undergoing different types of major surgery. METHODS: We performed a retrospective cohort study in a single tertiary health service, including all patients who underwent major surgery (orthopaedic, abdominal, cardiac or thoracic) between 1 May 2011 and 1 February 2022. The primary outcome was unplanned readmission to hospital in the 90 days following discharge after the index surgical procedure. These complex, non-linear relationships were modelled with restricted cubic splines. RESULTS: We identified 22,134 patients and included 14,635 in the primary analysis, of whom 1804 (12%) experienced at least one unplanned readmission. The odds of unplanned readmission rose when the discharge haemoglobin concentration was < 100 g.l-1 (p < 0.001). On subgroup analysis, the haemoglobin threshold below which odds of readmission began to increase appeared to be higher in patients undergoing emergency surgery (110 g.l-1; p < 0.001) compared with elective surgery. Declining discharge haemoglobin concentration was associated with increased odds ratios (95%CI) of unplanned readmission in patients undergoing orthopaedic (1.08 (1.01-1.15), p = 0.03), abdominal (1.13 (1.07-1.19), p < 0.001) and thoracic (1.12 (1.01-1.24), p = 0.03) procedures, but not cardiac surgery (1.09 (0.99-1.19), p = 0.07). CONCLUSIONS: Our findings suggest that a haemoglobin concentration < 100 g.l-1 following elective procedures and < 110 g.l-1 following emergency procedures, at the time of hospital discharge after major surgery, was associated with unplanned readmission. Future interventional trials that aim to treat postoperative anaemia and reduce unplanned readmission should include patients with discharge haemoglobin below these thresholds.

3.
Anal Bioanal Chem ; 407(15): 4351-62, 2015 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-25407427

RESUMO

Corticosterone (CORT) is the dominant plasma glucocorticoid in birds. There has been increasing interest in the function of CORT in avian egg yolk and in the potential to use CORT concentrations in eggs to quantify stress and to assess the effect of maternal stress on offspring. The concentration of CORT in egg yolk is most frequently assessed using enzyme or radioimmunoassays, alone or in combination with high-performance liquid chromatography. However, the quantification of CORT is frequently hampered by the presence of high concentrations of other steroid hormones which cross-react with the CORT antibody. As an alternative, we developed a sensitive and specific LC-MS-MS method. The sample-preparation procedure consisted of a protein-lipid precipitation step, followed by defatting and clean-up using a C18 SPE column. Chromatography was performed on an Acquity C18 BEH column (50 mm × 2.1 mm i.d., dp: 1.7 µm, run-time: 6 min), using 0.1% formic acid in both water (A) and acetonitrile (B) as mobile phases. The MS-MS instrument was operated in the positive-electrospray-ionization mode. The method was validated in-house according to European Guidelines (linearity, accuracy and precision, limits of quantification and detection, specificity, stability) and the results fell within the accepted ranges. The method was successfully used for the analysis of CORT in yolk and albumen of eggs collected from eight breeding lesser black-backed gulls at a Flemish coastal colony. CORT concentrations were in the range 42.4-166.3 pg g(-1) in albumen and < LOQ (75 pg g(-1))-762.5 pg g(-1) in yolk.


Assuntos
Corticosterona/análise , Clara de Ovo/química , Gema de Ovo/química , Espectrometria de Massas em Tandem/métodos , Animais , Charadriiformes , Precipitação Química , Galinhas , Cromatografia Líquida de Alta Pressão/métodos , Imunoensaio , Limite de Detecção , Extração em Fase Sólida/métodos
4.
Anal Chem ; 85(21): 10531-5, 2013 Nov 05.
Artigo em Inglês | MEDLINE | ID: mdl-24083320

RESUMO

Micromechanical photothermal infrared spectroscopy is a promising technique, where absorption-related heating is detected by frequency detuning of microstring resonators. We present photothermal infrared spectroscopy with mechanical string resonators providing rapid identification of femtogram-scale airborne samples. Airborne sample material is directly collected on the microstring with an efficient nondiffusion limited sampling method based on inertial impaction. Resonance frequency shifts, proportional to the absorbed heat in the microstring, are recorded as monochromatic IR light is scanned over the mid-infrared range. As a proof-of-concept, we sample and analyze polyvinylpyrrolidone (PVP) and the IR spectrum measured by photothermal spectroscopy matches the reference IR spectrum measured by an FTIR spectrometer. We further identify the organic surface coating of airborne TiO2 nanoparticles with a total mass of 4 pg. With an estimated detection limit of 44 fg, the presented sensor demonstrates a new paradigm in ultrasensitive vibrational spectroscopy for identification of airborne species.

5.
ERJ Open Res ; 9(2)2023 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-37020835

RESUMO

Background: Real-life evidence on prevalence and management of severe asthma is limited. Nationwide population registries across the Nordic countries provide unique opportunities to describe prevalence and management patterns of severe asthma at population level. In nationwide register data from Sweden, Norway and Finland, we examined the prevalence of severe asthma and the proportion of severe asthma patients being managed in specialist care. Methods: This is a cross-sectional study based on the Nordic Dataset for Asthma Research (NORDSTAR) research collaboration platform. We identified patients with severe asthma in adults (aged ≥18 years) and in children (aged 6-17 years) in 2018 according to the European Respiratory Society/American Thoracic Society definition. Patients managed in specialist care were those with an asthma-related specialist outpatient contact (only available in Sweden and Finland). Results: Overall, we identified 598 242 patients with current asthma in Sweden, Norway and Finland in 2018. Among those, the prevalence of severe asthma was 3.5%, 5.4% and 5.2% in adults and 0.4%, 1.0%, and 0.3% in children in Sweden, Norway and Finland, respectively. In Sweden and Finland, 37% and 40% of adult patients with severe asthma and two or more exacerbations, respectively, were managed in specialist care; in children the numbers were 56% and 41%, respectively. Conclusion: In three Nordic countries, population-based nationwide data demonstrated similar prevalence of severe asthma. In children, severe asthma was a rare condition. Notably, a large proportion of patients with severe asthma were not managed by a respiratory specialist, suggesting the need for increased recognition of severe asthma in primary care.

6.
J Infect Dis ; 204 Suppl 3: S1021-31, 2011 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-21987738

RESUMO

BACKGROUND: Marburg virus (MARV) infection causes a severe and often fatal hemorrhagic disease in primates; however, little is known about the development of MARV hemorrhagic fever. In this study we evaluated the progression of MARV infection in nonhuman primates. METHODS: Eighteen cynomolgus monkeys were infected with MARV; blood and tissues were examined sequentially over an 8-day period to investigate disease pathogenesis. RESULTS: Disease caused by MARV in cynomolgus macaques was very similar to disease previously described for Ebola virus-infected macaques. Monocytes, macrophages, Kupffer cells, and dendritic cells (DCs) were identified as the initial targets of MARV infection. Bystander lymphocyte apoptosis occurred at early stages in the disease course in intravascular and extravascular locations. The loss of splenic and lymph node DCs or downregulation of dendritic cell-specific intercellular adhesion molecule-3-grabbing non-integrin (DC-SIGN) on DCs as early as day 2 and continuing through day 8 after MARV infection was a prominent finding. Evidence of disseminated intravascular coagulation was noted; however, the degree of fibrin deposition in tissues was less prominent than was reported in Ebola-infected macaques. CONCLUSIONS: The sequence of pathogenic events identified in this study provides an understanding of the development of disease processes and also may provide new targets for rational prophylactic and chemotherapeutic interventions.


Assuntos
Doença do Vírus de Marburg/etiologia , Animais , Células Dendríticas/virologia , Imuno-Histoquímica , Fígado/patologia , Tecido Linfoide/citologia , Tecido Linfoide/patologia , Macaca fascicularis , Macrófagos/virologia , Doença do Vírus de Marburg/patologia , Doença do Vírus de Marburg/fisiopatologia , Monócitos/virologia
7.
Virol J ; 8: 205, 2011 May 06.
Artigo em Inglês | MEDLINE | ID: mdl-21548931

RESUMO

BACKGROUND: Lassa virus (LASV) infection causes an acute and sometimes fatal hemorrhagic disease in humans and nonhuman primates; however, little is known about the development of Lassa fever. Here, we performed a pilot study to begin to understand the progression of LASV infection in nonhuman primates. METHODS: Six cynomolgus monkeys were experimentally infected with LASV. Tissues from three animals were examined at an early- to mid-stage of disease and compared with tissues from three animals collected at terminal stages of disease. RESULTS: Dendritic cells were identified as a prominent target of LASV infection in a variety of tissues in all animals at day 7 while Kupffer cells, hepatocytes, adrenal cortical cells, and endothelial cells were more frequently infected with LASV in tissues of terminal animals (days 13.5-17). Meningoencephalitis and neuronal necrosis were noteworthy findings in terminal animals. Evidence of coagulopathy was noted; however, the degree of fibrin deposition in tissues was less prominent than has been reported in other viral hemorrhagic fevers. CONCLUSION: The sequence of pathogenic events identified in this study begins to shed light on the development of disease processes during Lassa fever and also may provide new targets for rational prophylactic and chemotherapeutic interventions.


Assuntos
Febre Lassa/veterinária , Vírus Lassa/patogenicidade , Doenças dos Primatas/patologia , Doenças dos Primatas/virologia , Experimentação Animal , Estruturas Animais/patologia , Estruturas Animais/virologia , Animais , Imuno-Histoquímica , Febre Lassa/patologia , Febre Lassa/virologia , Macaca fascicularis , Microscopia
8.
Sci Rep ; 10(1): 6426, 2020 Apr 14.
Artigo em Inglês | MEDLINE | ID: mdl-32286478

RESUMO

In this paper ultra clean monolayer and bilayer Chemical Vapor Deposited (CVD) graphene membranes with diameters up to 500 µm and 750 µm, respectively have been fabricated using Inverted Floating Method (IFM) followed by thermal annealing in vacuum. The yield decreases with size but we show the importance of choosing a good graphene raw material. Dynamic mechanical properties of the membranes at room temperature in different diameters are measured before and after annealing. The quality factor ranges from 200 to 2000 and shows no clear dependence on the size. The resonance frequency is inversely proportional to the diameter of the membranes. We observe a reduction of the effective intrinsic stress in the graphene, as well as of the relative error in the determination of said stress after thermal annealing. These measurements show that it is possible to produce graphene membranes with reproducible and excellent mechanical properties.

9.
Antimicrob Agents Chemother ; 53(6): 2620-5, 2009 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-19349521

RESUMO

ST-246, a potent orthopoxvirus egress inhibitor, is safe and effective at preventing disease and death in studies of small-animal models involving challenge by several different pathogenic poxviruses. In this report, the antiviral efficacy of ST-246 in treatment of nonhuman primates infected with variola virus or monkeypox virus was assessed. The data indicate that oral dosing once per day with ST-246 protects animals from poxvirus disease, as measured by reductions in viral load and numbers of lesions and enhancement of survival.


Assuntos
Antivirais/uso terapêutico , Benzamidas/uso terapêutico , Isoindóis/uso terapêutico , Mpox/prevenção & controle , Varíola/prevenção & controle , Animais , Feminino , Humanos , Macaca fascicularis , Masculino
10.
Rev Sci Instrum ; 90(4): 045006, 2019 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-31043020

RESUMO

We report on the design and operation of a world-to-chip microfluidic interface and experimental setup for fluidic micro- and nano-electromechanical systems. The central component of the interface is an engineered polyether ether ketone connector that brings fluid samples from a commercial syringe pump to the chip with the help of o-rings. In addition to that, the connector serves as an on-chip vacuum chamber. To confirm the adequate operation of our interface, we use complex microfluidic devices that were previously fabricated, suspended microchannel resonators, and demonstrate a fast exchange between fluids (on the scale of 130 s from isopropyl alcohol to water), in-vacuum operation of the devices (intrinsic damping regime), and accurate temperature control of the chip at different set points.

11.
Nat Commun ; 10(1): 4518, 2019 10 04.
Artigo em Inglês | MEDLINE | ID: mdl-31586068

RESUMO

Uncooled infrared detectors have enabled the rapid growth of thermal imaging applications. These detectors are predominantly bolometers, reading out a pixel's temperature change due to infrared radiation as a resistance change. Another uncooled sensing method is to transduce the infrared radiation into the frequency shift of a mechanical resonator. We present here highly sensitive resonant infrared sensors, based on thermo-responsive shape memory polymers. By exploiting the phase-change polymer as transduction mechanism, our approach provides 2 orders of magnitude improvement of the temperature coefficient of frequency. Noise equivalent temperature difference of 22 mK in vacuum and 112 mK in air are obtained using f/2 optics. The noise equivalent temperature difference is further improved to 6 mK in vacuum by using high-Q silicon nitride membranes as substrates for the shape memory polymers. This high performance in air eliminates the need for vacuum packaging, paving a path towards flexible non-hermetically sealed infrared sensors.

12.
Microsyst Nanoeng ; 5: 58, 2019.
Artigo em Inglês | MEDLINE | ID: mdl-31646000

RESUMO

Thermal analysis is essential for the characterization of polymers and drugs. However, the currently established methods require a large amount of sample. Here, we present pyrolytic carbon resonators as promising tools for micromechanical thermal analysis (MTA) of nanograms of polymers. Doubly clamped pre-stressed beams with a resonance frequency of 233 ± 4 kHz and a quality factor (Q factor) of 800 ± 200 were fabricated. Optimization of the electrical conductivity of the pyrolytic carbon allowed us to explore resistive heating for integrated temperature control. MTA was achieved by monitoring the resonance frequency and quality factor of the carbon resonators with and without a deposited sample as a function of temperature. To prove the potential of pyrolytic carbon resonators as thermal analysis tools, the glass transition temperature (T g) of semicrystalline poly(L-lactic acid) (PLLA) and the melting temperature (T m) of poly(caprolactone) (PCL) were determined. The results show that the T g of PLLA and T m of PCL are 61.0 ± 0.8 °C and 60.0 ± 1.0 °C, respectively, which are in excellent agreement with the values measured by differential scanning calorimetry (DSC).

13.
PLoS Med ; 2(6): e183, 2005 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-15971954

RESUMO

BACKGROUND: Recent importation of Lassa fever into Germany, the Netherlands, the United Kingdom, and the United States by travelers on commercial airlines from Africa underscores the public health challenge of emerging viruses. Currently, there are no licensed vaccines for Lassa fever, and no experimental vaccine has completely protected nonhuman primates against a lethal challenge. METHODS AND FINDINGS: We developed a replication-competent vaccine against Lassa virus based on attenuated recombinant vesicular stomatitis virus vectors expressing the Lassa viral glycoprotein. A single intramuscular vaccination of the Lassa vaccine elicited a protective immune response in nonhuman primates against a lethal Lassa virus challenge. Vaccine shedding was not detected in the monkeys, and none of the animals developed fever or other symptoms of illness associated with vaccination. The Lassa vaccine induced strong humoral and cellular immune responses in the four vaccinated and challenged monkeys. Despite a transient Lassa viremia in vaccinated animals 7 d after challenge, the vaccinated animals showed no evidence of clinical disease. In contrast, the two control animals developed severe symptoms including rashes, facial edema, and elevated liver enzymes, and ultimately succumbed to the Lassa infection. CONCLUSION: Our data suggest that the Lassa vaccine candidate based on recombinant vesicular stomatitis virus is safe and highly efficacious in a relevant animal model that faithfully reproduces human disease.


Assuntos
Febre Lassa/prevenção & controle , Vírus Lassa/imunologia , Vacinas Virais , Animais , Modelos Animais de Doenças , Avaliação Pré-Clínica de Medicamentos , Febre Lassa/imunologia , Macaca fascicularis , Vacinação , Vacinas Sintéticas , Vacinas Virais/imunologia , Viremia/prevenção & controle
14.
Lancet ; 362(9400): 1953-8, 2003 Dec 13.
Artigo em Inglês | MEDLINE | ID: mdl-14683653

RESUMO

BACKGROUND: Infection with the Ebola virus induces overexpression of the procoagulant tissue factor in primate monocytes and macrophages, suggesting that inhibition of the tissue-factor pathway could ameliorate the effects of Ebola haemorrhagic fever. Here, we tested the notion that blockade of fVIIa/tissue factor is beneficial after infection with Ebola virus. METHODS: We used a rhesus macaque model of Ebola haemorrhagic fever, which produces near 100% mortality. We administered recombinant nematode anticoagulant protein c2 (rNAPc2), a potent inhibitor of tissue factor-initiated blood coagulation, to the macaques either 10 min (n=6) or 24 h (n=3) after a high-dose lethal injection of Ebola virus. Three animals served as untreated Ebola virus-positive controls. Historical controls were also used in some analyses. FINDINGS: Both treatment regimens prolonged survival time, with a 33% survival rate in each treatment group. Survivors are still alive and healthy after 9 months. All but one of the 17 controls died. The mean survival for the six rNAPc2-treated macaques that died was 11.7 days compared with 8.3 days for untreated controls (p=0.0184). rNAPc2 attenuated the coagulation response as evidenced by modulation of various important coagulation factors, including plasma D dimers, which were reduced in nearly all treated animals; less prominent fibrin deposits and intravascular thromboemboli were observed in tissues of some animals that succumbed to Ebola virus. Furthermore, rNAPc2 attenuated the proinflammatory response with lower plasma concentrations of interleukin 6 and monocyte chemoattractant protein-1 (MCP-1) noted in the treated than in the untreated macaques. INTERPRETATION: Post-exposure protection with rNAPc2 against Ebola virus in primates provides a new foundation for therapeutic regimens that target the disease process rather than viral replication.


Assuntos
Fator VIIa/antagonistas & inibidores , Proteínas de Helminto/farmacologia , Doença pelo Vírus Ebola/tratamento farmacológico , Proteínas Recombinantes/farmacologia , Tromboplastina/antagonistas & inibidores , Animais , Coagulação Sanguínea/efeitos dos fármacos , Coagulação Sanguínea/imunologia , Modelos Animais de Doenças , Ebolavirus/efeitos dos fármacos , Ebolavirus/imunologia , Proteínas de Helminto/imunologia , Proteínas de Helminto/uso terapêutico , Doença pelo Vírus Ebola/imunologia , Doença pelo Vírus Ebola/mortalidade , Macaca mulatta , Proteínas Recombinantes/uso terapêutico , Taxa de Sobrevida , Replicação Viral/efeitos dos fármacos , Replicação Viral/imunologia
15.
ACS Macro Lett ; 3(1): 55-58, 2014 Jan 21.
Artigo em Inglês | MEDLINE | ID: mdl-35651109

RESUMO

Resonant microstrings show promise as a new analytical tool for thermal characterization of polymers with only few nanograms of sample. The detection of the glass transition temperature (Tg) of an amorphous poly(d,l-lactide) (PDLLA) and a semicrystalline poly(l-lactide) (PLLA) is investigated. The polymers are spray coated on one side of the resonating microstrings. The resonance frequency and quality factor (Q) are measured simultaneously as a function of temperature. Change in the resonance frequency reflects a change in static tensile stress, which yields information about the Young's modulus of the polymer, and a change in Q reflects the change in damping of the polymer-coated string. The frequency response of the microstring is validated with an analytical model. From the frequency independent tensile stress change, static Tg values of 40.6 and 57.6 °C were measured for PDLLA and PLLA, respectively. The frequency-dependent damping from Q indicates higher Tg values of 62.6 and 88.8 °C for PDLLA and PLLA, respectively, at ∼105 Hz. Resonant microstrings facilitate thermal analysis of nanogram polymer samples measuring the static and a dynamic glass transition temperature simultaneously.

16.
ACS Nano ; 7(7): 6188-93, 2013 Jul 23.
Artigo em Inglês | MEDLINE | ID: mdl-23799869

RESUMO

The ability to detect and analyze single sample entities such as single nanoparticles, viruses, spores, or molecules is of fundamental interest. This can provide insight into the individual specific properties which may differ from the statistical sample average. Here we introduce resonant photothermal spectroscopy, a novel method that enables the analysis of individual nanoparticulate samples. Absorption of light by an individual sample placed on a microstring resonator results in local heating of the string, which is reflected in its resonance frequency. The working principle of the spectrometer is demonstrated by analyzing the optical absorption of different micro- and nanoparticles on a microstring. We present the measurement of a simple absorption spectrum of multiple polystyrene microparticles illuminated with an unfocused LED light source. Using a diode laser, single 170 nm polystyrene nanoparticles are detected. With the current setup, nanoparticulate samples with a mass of ~40 ag are detectable. By using nanostrings, visible and infrared photothermal spectroscopy in the subattogram mass regime is possible and single molecule detection is within reach.


Assuntos
Espectroscopia Dielétrica/instrumentação , Teste de Materiais/instrumentação , Sistemas Microeletromecânicos/instrumentação , Nanoestruturas/química , Nanoestruturas/ultraestrutura , Nanotecnologia/instrumentação , Desenho de Equipamento , Análise de Falha de Equipamento , Temperatura Alta , Luz , Miniaturização , Tamanho da Partícula
17.
Expert Rev Vaccines ; 7(4): 417-29, 2008 May.
Artigo em Inglês | MEDLINE | ID: mdl-18444889

RESUMO

BACKGROUND: Virus-like particle (VLP)-based vaccines have the advantage of being morphologically and antigenically similar to the live virus from which they are derived. Expression of the glycoprotein and VP40 matrix protein from Lake Victoria marburgvirus (MARV) results in spontaneous production of VLPs in mammalian cells. Guinea pigs vaccinated with Marburg virus VLPs (mVLPs) or inactivated MARV (iMARV) develop homologous humoral and T-cell responses and are completely protected from a lethal homologous MARV challenge. AIMS & METHODS: To determine whether mVLPs based on the Musoke (aka Lake Victoria) isolate of MARV could broadly protect against diverse isolates of MARV, guinea pigs were vaccinated with mVLPs or iMARV-Musoke and challenged with MARV-Musoke, -Ravn or -Ci67. RESULTS: Prior to challenge, the mVLP- and iMARV-vaccinated guinea pigs had high levels of homologous MARV-Musoke and heterologous MARV-Ravn and -Ci67 antibodies. The Musoke-based mVLPs and iMARV vaccines provided complete protection in guinea pigs against viremia, viral replication and pathological changes in tissues, and lethal disease following challenge with MARV-Musoke, -Ravn or -Ci67. Guinea pigs vaccinated with RIBI adjuvant alone and infected with guinea pig-adapted MARV-Musoke, -Ravn or -Ci67 had histopathologic findings similar to those seen in the nonhuman primate model for MARV infection. Based on the strong protection observed in guinea pigs, we next vaccinated cynomolgus macaques with Musoke-based mVLPs and showed the VLP-vaccinated monkeys were broadly protected against three isolates of MARV (Musoke, Ravn and Ci67). CONCLUSION: Musoke mVLPs are effective at inducing broad heterologous immunity and protection against multiple MARV isolates.


Assuntos
Antígenos Virais/imunologia , Doença do Vírus de Marburg/prevenção & controle , Marburgvirus/genética , Virossomos/imunologia , Sequência de Aminoácidos , Estruturas Animais/patologia , Estruturas Animais/virologia , Animais , Anticorpos Antivirais/sangue , Antígenos Virais/genética , Cobaias , Macaca fascicularis , Marburgvirus/imunologia , Dados de Sequência Molecular , Alinhamento de Sequência , Análise de Sobrevida , Vacinas de Produtos Inativados/imunologia , Ensaio de Placa Viral , Vacinas Virais/imunologia , Viremia/prevenção & controle
18.
J Virol ; 81(14): 7449-62, 2007 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-17475651

RESUMO

Andes virus (ANDV) and Sin Nombre virus (SNV) are rodent-borne hantaviruses that cause a highly lethal hemorrhagic fever in humans known as hantavirus pulmonary syndrome (HPS). There are no vaccines or specific drugs to prevent or treat HPS, and the pathogenesis is not understood. Syrian hamsters infected with ANDV, but not SNV, develop a highly lethal disease that closely resembles HPS in humans. Here, we performed a temporal pathogenesis study comparing ANDV and SNV infections in hamsters. SNV was nonpathogenic and viremia was not detected despite the fact that all animals were infected. ANDV was uniformly lethal with a mean time to death of 11 days. The first pathology detected was lymphocyte apoptosis starting on day 4. Animals were viremic and viral antigen was first observed in multiple organs by days 6 and 8, respectively. Levels of infectious virus in the blood increased 4 to 5 logs between days 6 and 8. Pulmonary edema was first detected ultrastructurally on day 6. Ultrastructural analysis of lung tissues revealed the presence of large inclusion bodies and substantial numbers of vacuoles within infected endothelial cells. Paraendothelial gaps were not observed, suggesting that fluid leakage was transcellular and directly attributable to infecting virus. Taken together, these data imply that HPS treatment strategies aimed at preventing virus replication and dissemination will have the greatest probability of success if administered before the viremic phase; however, because vascular leakage is associated with infected endothelial cells, a therapeutic strategy targeting viral replication might be effective even at later times (e.g., after disease onset).


Assuntos
Infecções por Hantavirus/fisiopatologia , Orthohantavírus/patogenicidade , Vírus Sin Nombre/patogenicidade , Animais , Sequência de Bases , Chlorocebus aethiops , Cricetinae , Primers do DNA , Ensaio de Imunoadsorção Enzimática , Infecções por Hantavirus/sangue , Infecções por Hantavirus/patologia , Imuno-Histoquímica , Mesocricetus , Microscopia Eletrônica de Transmissão , Células Vero , Carga Viral , Ensaio de Placa Viral
19.
J Infect Dis ; 196 Suppl 2: S372-81, 2007 Nov 15.
Artigo em Inglês | MEDLINE | ID: mdl-17940973

RESUMO

BACKGROUND: The procoagulant tissue factor (TF) is thought to play a role in the coagulation disorders that characterize filoviral infections. In this study, we evaluated the pathogenesis of lethal infection with the Angola strain of Marburg virus (MARV-Ang) in rhesus macaques and tested the efficacy of recombinant nematode anticoagulant protein c2 (rNAPc2), an inhibitor of TF/factor VIIa, as a potential treatment. METHODS: Twelve rhesus macaques were challenged with a high dose (1000 pfu) of MARV-Ang. Six macaques were treated with rNAPc2, and 6 macaques served as control animals. RESULTS: All 6 control animals succumbed to MARV-Ang challenge by day 8 (mean, 7.3 days), whereas 5 of 6 rNAPc2-treated animals died on day 9 and 1 rNAPc2-treated animal survived. The disease course for MARV-Ang infection appeared to progress more rapidly in rhesus macaques than has been previously reported for other strains of MARV. In contrast to Ebola virus (EBOV) infection in macaques, up-regulation of TF was not as striking, and deposition of fibrin was a less prominent pathologic feature of disease in these animals. CONCLUSIONS: These data show that the pathogenicity of MARV-Ang infection appears to be consistent with the apparent increased human virulence attributed to this strain. The apparent reduced efficacy of rNAPc2 against MARV-Ang infection, compared with its efficacy against EBOV infection, appears to be associated with differences in TF induction and fibrin deposition.


Assuntos
Proteínas de Helminto/uso terapêutico , Doença do Vírus de Marburg/tratamento farmacológico , Doença do Vírus de Marburg/epidemiologia , Marburgvirus/patogenicidade , Angola/epidemiologia , Animais , Macaca mulatta , Doenças dos Primatas/tratamento farmacológico , Doenças dos Primatas/epidemiologia , Proteínas Recombinantes/uso terapêutico
20.
J Infect Dis ; 196 Suppl 2: S390-9, 2007 Nov 15.
Artigo em Inglês | MEDLINE | ID: mdl-17940975

RESUMO

BACKGROUND: Infection of primates with Zaire ebolavirus (ZEBOV) leads to hypotension, coagulation disorders, and an impaired immune response and, in many ways, resembles severe sepsis. Rapid decreases in plasma levels of protein C are a prominent feature of severe sepsis and ZEBOV hemorrhagic fever (ZHF). Currently, recombinant human activated protein C (rhAPC [Xigris; Eli Lilly]) is licensed for treating human patients with severe sepsis who are at high risk of death. The aim of this study was to test the efficacy of rhAPC as a potential treatment for ZHF. METHODS: Fourteen rhesus macaques were challenged with a uniformly lethal dose of ZEBOV; 11 of these monkeys were treated by intravenous infusion with rhAPC beginning 30-60 min after challenge and continuing for 7 days. Three control monkeys received sterile saline in parallel. RESULTS: All 3 control monkeys died on day 8, whereas 2 of the 11 rhAPC-treated monkeys survived. The mean time to death for the rhAPC-treated monkeys that did not survive ZEBOV challenge was 12.6 days. The difference in survival was significant when the rhAPC-treated monkeys were compared with historical controls. CONCLUSIONS: The experimental findings provide evidence that ZHF and severe sepsis share underlying mechanisms and may respond to the same therapies.


Assuntos
Ebolavirus/isolamento & purificação , Doença pelo Vírus Ebola/tratamento farmacológico , Proteína C/uso terapêutico , Animais , Cateterismo Venoso Central , Modelos Animais de Doenças , Macaca mulatta , Oligopeptídeos/uso terapêutico , Primatas , Proteína C/administração & dosagem , Proteína C/genética , Proteínas Recombinantes/administração & dosagem , Proteínas Recombinantes/uso terapêutico
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