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The Ma_MISS miniaturized spectrometer is integrated within the Drilling System of the ExoMars Rosalind Franklin Rover for Mars exploration. Here we focus on the on ground calibration campaign to obtain radiometric and linearity calibrations of the Ma_MISS instrument, while the first paper dealt with the spectral calibration [De Angelis et al., Rev. Sci. Instrum. 93, 123704 (2022)]. The experimental setup used to carry out radiometric calibration is described, as are the methods used for data processing and key parameter retrieval. In particular, the Spectrometer Transfer Function (Responsivity), Signal-to-Noise Ratio, and detector linearity are determined. In a third paper [De Sanctis et al., Planet. Sci. J. 3, 142 (2022)], validation of the Ma_MISS calibration results through spectral measurements performed on rock and synthetic targets during the radiometric calibration campaign is described.
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The Mars Multispectral Imager for Subsurface Studies (Ma_MISS) instrument is a miniaturized visible and near-infrared spectrometer that is integrated into the drilling system of the ESA Rosalind Franklin rover, which is devoted to subsurface exploration on Mars. Ma_MISS will acquire spectral data on the Martian subsurface from excavated borehole walls. The spectral data collected by Ma_MISS on unexposed rocks will be crucial for determination of the composition of subsurface rocks and optical and physical properties of materials (i.e., grain size). Ma_MISS will further contribute to a reconstruction of the stratigraphic column and acquire data on subsurface geological processes. Ma_MISS data may also inform with regard to the presence of potential biomarkers in the subsurface, given the presence of organic matter that may affect some spectral parameters. In this framework, we performed a wide range of measurements using the laboratory model of the Ma_MISS to investigate mineral/organic mixtures in different proportions. We prepared mixtures by combining kaolinite and nontronite with glycine, asphaltite, polyoxymethylene, and benzoic acid. These organic compounds show different spectral characteristics in the visible and near-infrared; therefore their presence can be detected by the Ma_MISS instrument. Our results indicate that the Ma_MISS instrument can detect organic material down to abundances of around 1 wt %. In particular, the data collected on low-concentration mixtures show that, by analyzing sediments with a grain size smaller than the Ma_MISS spatial resolution, the instrument can still discern those points where organic matter is present from points with exclusive mineral composition. The results also show that a collection of multiple contiguous measurements on a hypothetical borehole wall could help indicate the presence of organic matter in clay-rich soils if present.
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Meio Ambiente Extraterreno , Marte , Exobiologia/métodos , Minerais , Fenômenos GeológicosRESUMO
The Ma_MISS spectrometer is integrated within the drilling system of the Rosalind Franklin ExoMars rover. This paper reports the on-ground calibration campaign performed on the spectrometer. Here, we focus on the spectral calibration of the instrument. The experimental setup used to carry out calibration is described, and the methods used for data processing and key parameters retrieval are explained. In particular, the spectral parameters such as (i) pixel central wavelengths, (ii) spectral response function, (iii) spectral resolution, (iv) sampling, and (v) range are determined. In a follow-up paper, the linearity and radiometric calibrations are described, while in De Sanctis et al. [Planet. Sci. J. 3, 142 (2022)], the validation of spectral measurements performed on synthetic and natural rock targets is presented.
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The Nadir and Occultation for MArs Discovery (NOMAD) instrument suite aboard ExoMars/Trace Gas Orbiter spacecraft is mainly conceived for the study of minor atmospheric species, but it also offers the opportunity to investigate surface composition and aerosols properties. We investigate the information content of the Limb, Nadir, and Occultation (LNO) infrared channel of NOMAD and demonstrate how spectral orders 169, 189, and 190 can be exploited to detect surface CO2 ice. We study the strong CO2 ice absorption band at 2.7 µm and the shallower band at 2.35 µm taking advantage of observations across Martian Years 34 and 35 (March 2018 to February 2020), straddling a global dust storm. We obtain latitudinal-seasonal maps for CO2 ice in both polar regions, in overall agreement with predictions by a general climate model and with the Mars Express/OMEGA spectrometer Martian Years 27 and 28 observations. We find that the narrow 2.35 µm absorption band, spectrally well covered by LNO order 189, offers the most promising potential for the retrieval of CO2 ice microphysical properties. Occurrences of CO2 ice spectra are also detected at low latitudes and we discuss about their interpretation as daytime high altitude CO2 ice clouds as opposed to surface frost. We find that the clouds hypothesis is preferable on the basis of surface temperature, local time and grain size considerations, resulting in the first detection of CO2 ice clouds through the study of this spectral range. Through radiative transfer considerations on these detections we find that the 2.35 µm absorption feature of CO2 ice clouds is possibly sensitive to nm-sized ice grains.
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Static computer-assisted surgery (s-CAS) has been introduced to improve the results of implantology. A prospective cohort study was conducted following the STROBE guidelines to determine the presence of a learning curve in s-CAS. Six partially and six totally edentulous patients were treated by two surgeons experienced in implantology but completely inexperienced in s-CAS. Preoperative and postoperative computed tomography scans were matched to assess coronal, apical, and angular deviation and the positioning error. The accuracy data were used to evaluate the learning curve. Fifty-six implants were inserted. In partially and totally edentulous patients, the mean (range; standard deviation) coronal deviation was 0.87 (0.34-1.27; 0.35) and 1.24 (0.72-2.67; 0.79); the mean apical deviation was 1.13 (0.48-1.63; 0.39) and 1.52 (0.88-3.84; 1.15); the mean angular deviation was 2.63 (1.89-4.50; 0.98) and 3.59 (1.69-6.30; 1.65); and the mean positioning error was 0.80 (0.32-1.25; 0.35) and 1.14 (0.35-2.56; 0.77), respectively. A typical 'learning curve' effect was not identified for s-CAS.
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Implantes Dentários , Cirurgia Assistida por Computador , Desenho Assistido por Computador , Implantação Dentária Endóssea , Humanos , Curva de Aprendizado , Planejamento de Assistência ao Paciente , Estudos ProspectivosRESUMO
The aim of this study was to evaluate the effectiveness of loading at 2 months after the surgical placement of implants. A tapered implant was used. Implant stability was determined using resonance frequency analysis at implant insertion (T0; primary stability), after 2 months (T1), and at the 6-month follow-up (T2). Descriptive statistics and the t-test were used. Significance was at P ≤ 0.05. A total of 268 implants were inserted in 142 patients. No patient dropped out and no implant had failed at the 6-month follow-up. The mean implant stability quotient value (ISQ) increased over time, with a statistically non-significant difference for T0 vs. T1 (P = 0.08) and a statistically significant difference for T1 vs. T2 (P = 0.0018) and T0 vs. T2 (P = 0.000). Only 99 implants, characterized by an extremely high mean primary stability value (80.34), did not have a recorded increase in ISQ at T1. A 2-month healing period allowed the implant to achieve secondary stability, confirming the effectiveness of the loading protocol at 2 months.
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Implantes Dentários , Osseointegração , Estudos de Coortes , Implantação Dentária Endóssea , Planejamento de Prótese Dentária , Humanos , Estudos ProspectivosRESUMO
The instrument JIRAM (Jovian Infrared Auroral Mapper), on board the NASA spacecraft Juno, is both an imager and a spectrometer. Two distinct detectors are used for imaging and spectroscopy. The imager acquires Jupiter images in two bands, one of which (L band, 3.3-3.6 µm) is devoted to monitor the H3+ emission. The spectrometer covers the spectral region from 2 to 5 µm (average spectral resolution 9 nm) with a 256 pixels slit that can observe the same scene of the L band imager with some delay. JIRAM scientific goals are the exploration of the Jovian aurorae and the planet's atmospheric structure, dynamics and composition. Starting early July 2016 Juno is orbiting around Jupiter. Since then, JIRAM has provided an unprecedented amount of measurements, monitoring both Jupiter's atmosphere and aurorae. In particular, the camera has monitored Jupiter's poles with very high spatial resolution, providing new insights in both its aurorae and the polar dynamic. The main findings obtained by the L imager are detailed pictures of Jupiter's aurorae showing an extremely complex morphology of the H3+ distribution in the main oval and in the moon's footprints. The spectrometer has enabled the measure the distribution of both H3+ concentration and temperature. The analysis of the north auroral region limb observations shows that the peak density of H3+ is above 750 km and that often it is anticorrelated to the temperature, confirming the infrared cooling effect of H3+. This article is part of a discussion meeting issue 'Advances in hydrogen molecular ions: H3+, H5+ and beyond'.
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We characterize the origin and evolution of a mesoscale wave pattern in Jupiter's North Equatorial Belt (NEB), detected for the first time at 5 µm using a 2016-17 campaign of "lucky imaging" from the VISIR instrument on the Very Large Telescope and the NIRI instrument on the Gemini observatory, coupled with M-band imaging from Juno's JIRAM instrument during the first seven Juno orbits. The wave is compact, with a 1°.1-1°.4 longitude wavelength (wavelength 1300-1600 km, wavenumber 260-330) that is stable over time, with wave crests aligned largely north-south between 14°N and 17°N (planetographic). The waves were initially identified in small (10° longitude) packets immediately west of cyclones in the NEB at 16°N but extended to span wider longitude ranges over time. The waves exhibit a 7-10 K brightness temperature amplitude on top of an â¼210 K background at 5 µm. The thermal structure of the NEB allows for both inertio-gravity waves and gravity waves. Despite detection at 5 µm, this does not necessarily imply a deep location for the waves, and an upper tropospheric aerosol layer near 400-800 mbar could feature a gravity wave pattern modulating the visible-light reflectivity and attenuating the 5-µm radiance originating from deeper levels. Strong rifting activity appears to obliterate the pattern, which can change on timescales of weeks. The NEB underwent a new expansion and contraction episode in 2016-17 with associated cyclone-anticyclone formation, which could explain why the mesoscale wave pattern was more vivid in 2017 than ever before.
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Jupiter's aurorae are produced in its upper atmosphere when incoming high-energy electrons precipitate along the planet's magnetic field lines. A northern and a southern main auroral oval are visible, surrounded by small emission features associated with the Galilean moons. We present infrared observations, obtained with the Juno spacecraft, showing that in the case of Io, this emission exhibits a swirling pattern that is similar in appearance to a von Kármán vortex street. Well downstream of the main auroral spots, the extended tail is split in two. Both of Ganymede's footprints also appear as a pair of emission features, which may provide a remote measure of Ganymede's magnetosphere. These features suggest that the magnetohydrodynamic interaction between Jupiter and its moon is more complex than previously anticipated.
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The aim of this report was to describe a new computer-guided technique for a controlled site preparation and palatal orthodontic miniscrew insertion using a dedicated software. A surgical guide was designed after planning the appropriate insertion sites on three-dimensional images created by the fusion of cone-beam computed tomography (CBCT) and digital dental model images. Pre- and postoperative CBCT images were compared and the angular, coronal, and apical deviations between the planned and the placed miniscrews were calculated. The mean coronal and apical deviations were 1.38mm (range: 3.48-0.15mm; standard deviation (SD): 0.65) and 1.73mm (range: 5.41-0.10mm; SD: 1.03), respectively, while the mean angular deviation was 4.60° (range: 15.23-0.54°; SD: 2.54). The present surgical guide allows a controlled and accurate palatal miniscrew placement in three dimensions.
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Parafusos Ósseos , Desenho Assistido por Computador , Procedimentos de Ancoragem Ortodôntica/métodos , Palato Duro/diagnóstico por imagem , Palato Duro/cirurgia , Cirurgia Assistida por Computador/métodos , Tomografia Computadorizada de Feixe Cônico , Humanos , Imageamento Tridimensional , Itália , Procedimentos Cirúrgicos Minimamente Invasivos , Modelos Dentários , Radiografia Dentária Digital , SoftwareRESUMO
The familiar axisymmetric zones and belts that characterize Jupiter's weather system at lower latitudes give way to pervasive cyclonic activity at higher latitudes. Two-dimensional turbulence in combination with the Coriolis ß-effect (that is, the large meridionally varying Coriolis force on the giant planets of the Solar System) produces alternating zonal flows. The zonal flows weaken with rising latitude so that a transition between equatorial jets and polar turbulence on Jupiter can occur. Simulations with shallow-water models of giant planets support this transition by producing both alternating flows near the equator and circumpolar cyclones near the poles. Jovian polar regions are not visible from Earth owing to Jupiter's low axial tilt, and were poorly characterized by previous missions because the trajectories of these missions did not venture far from Jupiter's equatorial plane. Here we report that visible and infrared images obtained from above each pole by the Juno spacecraft during its first five orbits reveal persistent polygonal patterns of large cyclones. In the north, eight circumpolar cyclones are observed about a single polar cyclone; in the south, one polar cyclone is encircled by five circumpolar cyclones. Cyclonic circulation is established via time-lapse imagery obtained over intervals ranging from 20 minutes to 4 hours. Although migration of cyclones towards the pole might be expected as a consequence of the Coriolis ß-effect, by which cyclonic vortices naturally drift towards the rotational pole, the configuration of the cyclones is without precedent on other planets (including Saturn's polar hexagonal features). The manner in which the cyclones persist without merging and the process by which they evolve to their current configuration are unknown.
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The Visible and near Infrared Hyperspectral Imager (VIHI) is the VIS-IR spectrometer with imaging capabilities aboard the ESA BepiColombo mission to Mercury. In this second paper, we report the instrument spectral characterization derived by the calibration campaign carried out before spacecraft integration. Complementary measurements concerning radiometric and linearity responses, as well as geometric performances, are described in Paper I [G. Filacchione et al., Rev. Sci. Instrum. 88, 094502 (2017)]. We have verified the VIHI spectral range, spectral dispersion, spectral response function, and spectral uniformity along the whole slit. Instrumental defects and optical aberrations due to smiling and keystone effects have been evaluated, and they are lower than the design requirement (<1/3 pixel). The instrumental response is uniform along the whole slit, while spectral dispersion is well represented by a second order curve, rather than to be constant along the spectral dimension.
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The brass wire ligature is an efficient method to correct a moderately mesially impacted mandibular second molar (MM2). The aim of this prospective clinical pilot study was to evaluate the influence of mandibular third molar (MM3) germectomy on the treatment time for this procedure and to determine its impact on oral health-related quality of life (OHRQoL) using the short-form Oral Health Impact Profile (OHIP-14). The STROBE guidelines were followed. Impacted MM2 were assigned randomly to receive brass wire ligature treatment either with germectomy (group A) or without germectomy (group B). Descriptive statistics and the Student t-test were used in the statistical analysis; significance was set at P≤0.05. One thousand and thirty patients were assessed. Fourteen subjects with 20 mesially angulated (range 25-40°) impacted MM2 were identified. Paired comparisons of groups A and B showed no statistically significant difference in treatment time (171days for group A and 174days for group B; P=0.440), but a statistically significant difference in OHIP-14 values at the 3- (P=0.017) and 7-day (P=0.002) follow-up. The brass wire technique can be used effectively in moderately impacted MM2, but the combined use of MM3 germectomy does not influence the treatment time and shows a negative impact on OHRQoL.
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Ligadura/instrumentação , Mandíbula/cirurgia , Dente Molar/cirurgia , Qualidade de Vida , Extração Dentária/métodos , Dente Impactado/cirurgia , Adolescente , Cobre , Feminino , Humanos , Masculino , Dente Molar/diagnóstico por imagem , Dente Serotino/diagnóstico por imagem , Dente Serotino/cirurgia , Projetos Piloto , Estudos Prospectivos , Radiografia Panorâmica , Retalhos Cirúrgicos , Dente Impactado/diagnóstico por imagem , Resultado do Tratamento , ZincoRESUMO
The peroxisome proliferator-activated receptors (PPARs) belong to the nuclear receptor superfamily. In the last years novel PPARs ligands have been identified and these include PPARα/γ dual agonists. To rapidly identify novel PPARs dual ligands, a robust binding assay amenable to high-throughput screening toward PPAR isoforms would be desirable. In this work we describe a parallel assay based on the principles of frontal affinity chromatography coupled to mass spectrometry (FAC-MS) that can be used to characterize dual agonists. For this purpose the ligand binding domain of PPARα receptor was immobilized onto the surface of open tubular capillaries to create new PPAR-alpha-OT columns to be used in parallel with PPAR-gamma-OT columns. The two biochromatographic systems were used in both ranking and Kd experiments toward new ureidofibrate-like dual agonists for subtype selectivity ratio determination. In order to validate the system, the Kd values determined by frontal analysis chromatography were compared to the affinity constants obtained by ITC experiments. The results of this study strongly demonstrate the specific nature of the interaction of the ligands with the two immobilized receptor subtypes.
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Cromatografia de Afinidade/instrumentação , Cromatografia de Afinidade/métodos , Espectrometria de Massas/métodos , PPAR alfa/química , PPAR gama/química , Calorimetria , Descoberta de Drogas/métodos , Proteínas Imobilizadas/agonistas , Proteínas Imobilizadas/química , Proteínas Imobilizadas/metabolismo , Ligantes , PPAR alfa/agonistas , PPAR alfa/metabolismo , PPAR gama/agonistas , PPAR gama/metabolismo , Ligação Proteica , Reprodutibilidade dos TestesRESUMO
A series of ureidofibrate-like derivatives was prepared and assayed for their PPAR functional activity. A calorimetric approach was used to characterize PPARγ-ligand interactions, and docking experiments and X-ray studies were performed to explain the observed potency and efficacy. R-1 and S-1 were selected to evaluate several aspects of their biological activity. In an adipogenic assay, both enantiomers increased the expression of PPARγ target genes and promoted the differentiation of 3T3-L1 fibroblasts to adipocytes. In vivo administration of these compounds to insulin resistant C57Bl/6J mice fed a high fat diet reduced visceral fat content and body weight. Examination of different metabolic parameters showed that R-1 and S-1 are insulin sensitizers. Notably, they also enhanced the expression of hepatic PPARα target genes indicating that their in vivo effects stemmed from an activation of both PPARα and γ. Finally, the capability of R-1 and S-1 to inhibit cellular proliferation in colon cancer cell lines was also evaluated.
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Benzoxazóis/química , Ácidos Fíbricos/química , PPAR alfa/metabolismo , PPAR gama/metabolismo , Propionatos/química , Ureia/química , Adipócitos/citologia , Adipócitos/efeitos dos fármacos , Adipócitos/metabolismo , Animais , Antineoplásicos/síntese química , Antineoplásicos/química , Antineoplásicos/farmacologia , Benzoxazóis/síntese química , Benzoxazóis/farmacologia , Peso Corporal/efeitos dos fármacos , Calorimetria , Diferenciação Celular/efeitos dos fármacos , Linhagem Celular , Linhagem Celular Tumoral , Proliferação de Células/efeitos dos fármacos , Cristalografia por Raios X , Agonismo Parcial de Drogas , Ensaios de Seleção de Medicamentos Antitumorais , Fibroblastos/citologia , Fibroblastos/efeitos dos fármacos , Fibroblastos/metabolismo , Perfilação da Expressão Gênica , Humanos , Resistência à Insulina , Gordura Intra-Abdominal/efeitos dos fármacos , Fígado/efeitos dos fármacos , Fígado/metabolismo , Camundongos , Camundongos Endogâmicos C57BL , Modelos Moleculares , PPAR alfa/agonistas , PPAR alfa/genética , PPAR gama/agonistas , PPAR gama/genética , Propionatos/síntese química , Propionatos/farmacologia , Estereoisomerismo , Relação Estrutura-AtividadeRESUMO
In patients with rheumatoid arthritis (RA) a decrease in the terminal galactose content of N-linked glycans of the Fc region of agalactosyl immunoglobulin G (IgG) (G0) occurs. The aim of this study was to evaluate, for the first time, the effect of infliximab, a new monoclonal antibody for the treatment of RA, on this phenomenon. A total of 19 patients with active RA were treated with intravenous infliximab (3 mg/kg) in combination with methotrexate (MTX) (10-20 mg). IgG was purified from their serum by caprylic acid. Analysis of IgG glycosylation was performed by lectin blotting/immunoblotting and enzyme linked lectin assay (ELLA)/enzyme linked immunosorbent assay (ELISA) using the Griffonia (bandeiraea) simplicifolia lectin II and protein-A/alkaline phosphatase. The purity of IgG samples obtained was higher than 90%. The sensitivity of the lectin/immunoblotting method was of about 0.25 microg of IgG. The inter- and intraassay coefficients of variation (CV) were 1.3% and 9.0% for lectin blotting, and 4.6% and 8.3% for immunoblotting, respectively. The sensitivity of the ELLA/ELISA approach was 0.025 microg/microL and the inter- and intraassay CV were 6.2% and 7.7% for ELLA, and 5.1% and 14.1% for ELISA, respectively. A good linear correlation (r2=0.18, P<0.05) was obtained between the two different experimental approaches. A decrease of G0 was observed in patients who clinically improved (according to the American College of Rheumatology criteria) following the pharmacological treatment. Our data indicate that infliximab can reduce the concentration of G0 in patients with active RA.
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Anticorpos Monoclonais/farmacologia , Antirreumáticos/farmacologia , Artrite Reumatoide/tratamento farmacológico , Imunoglobulina G/efeitos dos fármacos , Anticorpos Monoclonais/uso terapêutico , Antirreumáticos/uso terapêutico , Caprilatos/química , Ensaio de Imunoadsorção Enzimática , Feminino , Glicosilação/efeitos dos fármacos , Humanos , Immunoblotting , Imunoglobulina G/sangue , Imunoglobulina G/metabolismo , Infliximab , Masculino , Pessoa de Meia-IdadeRESUMO
The possible enzymatic activities of neuro- and cytoglobin as well as their potential function as substrates in enzymatic reactions were studied. Neuro- and cytoglobin are found to show no appreciable superoxide dismutase, catalase, and peroxidase activities. However, the internal disulfide bond (CD7-D5) of human neuroglobin can be reduced by thioredoxin reductase. Furthermore, our in vivo and in vitro studies show that Escherichia coli cells contain an enzymatic reducing system that keeps the heme iron atom of neuroglobin in the Fe(2+) form in the presence of dioxygen despite the high autoxidation rate of the molecule. This reducing system needs a low-molecular-weight compound as co-factor. In vitro tests show that both NADH and NADPH can play this role. Furthermore, the reducing system is not specific for neuroglobin but allows the reduction of the ferric forms of other globins such as cytoglobin and myoglobin. A similar reducing system is present in eukaryotic tissue protein extracts.
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Enzimas/metabolismo , Globinas/metabolismo , Proteínas do Tecido Nervoso/metabolismo , Animais , Catalase/metabolismo , Dissulfetos/química , Dissulfetos/metabolismo , Globinas/química , Globinas/genética , Heme/química , Heme/metabolismo , Humanos , Ferro/química , Ferro/metabolismo , NAD/metabolismo , NADP/metabolismo , Proteínas do Tecido Nervoso/química , Proteínas do Tecido Nervoso/genética , Neuroglobina , Oxirredução , Peroxidase/metabolismo , Espectrofotometria , Análise Espectral Raman , Especificidade por Substrato , Superóxido Dismutase/metabolismo , Tiorredoxina Dissulfeto Redutase/metabolismoRESUMO
The recent identification of large deposits of sulphates by remote sensing and in situ observations has been considered evidence of the past presence of liquid water on Mars. Here we report the unambiguous detection of diverse phyllosilicates, a family of aqueous alteration products, on the basis of observations by the OMEGA imaging spectrometer on board the Mars Express spacecraft. These minerals are mainly associated with Noachian outcrops, which is consistent with an early active hydrological system, sustaining the long-term contact of igneous minerals with liquid water. We infer that the two main families of hydrated alteration products detected-phyllosilicates and sulphates--result from different formation processes. These occurred during two distinct climatic episodes: an early Noachian Mars, resulting in the formation of hydrated silicates, followed by a more acidic environment, in which sulphates formed.
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Silicatos de Alumínio/análise , Silicatos de Alumínio/química , Clima , Meio Ambiente Extraterreno/química , Marte , Argila , Concentração de Íons de Hidrogênio , Ferro/análise , Magnésio/análise , Voo Espacial , Astronave , Sulfatos/análise , Sulfatos/química , Água/análise , Água/químicaRESUMO
Data from the Observatoire pour la Minéralogie, l'Eau, les Glaces, et l'Activité (OMEGA) on the Mars Express spacecraft identify the distinct mafic, rock-forming minerals olivine, low-calcium pyroxene (LCP), and high-calcium pyroxene (HCP) on the surface of Mars. Olivine- and HCP-rich regions are found in deposits that span the age range of geologic units. However, LCP-rich regions are found only in the ancient Noachian-aged units, which suggests that melts for these deposits were derived from a mantle depleted in aluminum and calcium. Extended dark regions in the northern plains exhibit no evidence of strong mafic absorptions or absorptions due to hydrated materials.
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Compostos de Ferro , Compostos de Magnésio , Marte , Minerais , Silicatos , Absorção , Atmosfera , Cálcio , Meio Ambiente Extraterreno , Sedimentos Geológicos , Astronave , Espectroscopia de Luz Próxima ao Infravermelho , Análise Espectral , Tempo , ÁguaRESUMO
A microassay was developed to detect human herpesvirus 6 (HHV-6) binding to its cellular receptor using flow cytometry. Comparable results were obtained either by using HHV-6 preparations conjugated with fluorescein isothiocyanate or by indirect immunofluorescent labeling of membrane-bound virus using as primary antibody a monoclonal antibody specific for the HHV-6 gp60/110 envelope glycoprotein. Virus attachment to the plasma membrane was specific and saturable. As expected, among cell lines of various origin, maximum binding was detected on human T-lymphoid cells (HSB-2). Papain digestion of HSB-2 cells prevented HHV-6 attachment and reduced significantly virus infection, indicating the involvement of a protein-based receptor in the attachment step. After removal of the protease, virus receptors were resynthesized and their regeneration was prevented partially by cycloheximide, an inhibitor of protein synthesis. Unexpectedly, only high concentrations (mg/ml) of soluble heparan sulfate and heparin inhibited HHV-6 binding and infection. Under the same conditions, few micrograms (per ml) of heparin suppressed completely herpes simplex type 1 (HSV-1) attachment to the same cell line. Treatment of HSB-2 cells with heparitinase and heparinase, at doses that reduced significantly HSV-1 attachment, had little effect on HHV-6 binding to the cell membrane, indicating a different requirement of heparan sulfate-containing glycosaminoglycans for the two herpesviruses. These data suggest that protein components of the cellular membrane play an essential role in HHV-6 binding and infection while heparan sulfate-glycos-aminoglycans appear to be involved only partially in virus-receptor interaction.