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1.
Space Weather ; 15(2): 325-342, 2017 Feb.
Artículo en Inglés | MEDLINE | ID: mdl-28824340

RESUMEN

We present a multi-year superposed epoch study of the Sounding of the Atmosphere using Broadband Emission Radiometry nitric oxide (NO) emission data. NO is a trace constituent in the thermosphere that acts as cooling agent via infrared (IR) emissions. The NO cooling competes with storm time thermospheric heating resulting in a thermostat effect. Our study of nearly 200 events reveals that shock-led interplanetary coronal mass ejections (ICMEs) are prone to early and excessive thermospheric NO production and IR emissions. Excess NO emissions can arrest thermospheric expansion by cooling the thermosphere during intense storms. The strongest events curtail the interval of neutral density increase and produce a phenomenon known as thermospheric 'overcooling'. We use Defense Meteorological Satellite Program particle precipitation data to show that interplanetary shocks and their ICME drivers can more than double the fluxes of precipitating particles that are known to trigger the production of thermospheric NO. Coincident increases in Joule heating likely amplify the effect. In turn, NO emissions more than double. We discuss the roles and features of shock/sheath structures that allow the thermosphere to temper the effects of extreme storm time energy input and explore the implication these structures may have on mesospheric NO. Shock-driven thermospheric NO IR cooling likely plays an important role in satellite drag forecasting challenges during extreme events.

2.
Ann ICRP ; 49(1_suppl): 154-157, 2020 Dec.
Artículo en Inglés | MEDLINE | ID: mdl-32734767

RESUMEN

As radiation therapy is needed by approximately 50% of patients with cancer there needs to be ongoing research to ensure that radiation therapy targets the tumour effectively and minimises potential side effects. Major advances in radiation therapy, due to improvements in engineering and computing, have made it more precise, reducing side effects and improving cancer control. Patients need to be informed of its risks, both short and long term, to enable them to be active participants in their cancer treatment path.


Asunto(s)
Atención a la Salud/estadística & datos numéricos , Neoplasias/radioterapia , Medicina Nuclear/estadística & datos numéricos , Pacientes/psicología , Radioterapia/psicología , Humanos
3.
Nurse Educ Pract ; 45: 102795, 2020 May.
Artículo en Inglés | MEDLINE | ID: mdl-32442930

RESUMEN

Prisoners' access to healthcare should mirror that of the general public, but is adversely affected by challenges in recruiting nurses to work in custodial settings, potentially impacting on prisoner well-being. To address this issue prison-based insight-days have been developed jointly by one university and prison to positively influence students' views of undertaking placements in custodial settings because nurses are known to subsequently seek employment in areas where they have had positive student placements. A phenomenological investigation explored student nurses' lived experiences of prison-based insight-days. Questionnaires and interviews were used to gather qualitative data about students' feelings both prior to and following the insight-day (n = 17). All data was thematically analysed resulting in four themes: pre-placement curiosity, escalating admission anxiety, calming down inside and post-placement decision making. The empirical findings showed that first-hand exposure to prisoners, and to the realities of a working prison, were crucial factors in dispelling stereotypes and addressing negative preconceptions of prison healthcare environments, as students could find prison placements unexpectedly appealing. Drawing on the findings, this paper recommends that facilitating prison insight-days within custodial settings may be one way to encourage students to undertake prison placements.


Asunto(s)
Actitud del Personal de Salud , Percepción , Prisiones , Estudiantes de Enfermería/psicología , Bachillerato en Enfermería , Femenino , Humanos , Investigación Cualitativa , Encuestas y Cuestionarios
4.
Ann Bot ; 102(4): 561-9, 2008 Oct.
Artículo en Inglés | MEDLINE | ID: mdl-18628262

RESUMEN

BACKGROUND AND AIMS: Accurately representing development is essential for applying crop simulations to investigate the effects of climate, genotypes or crop management. Development in wheat (Triticum aestivum, T. durum) is primarily driven by temperature, but affected by vernalization and photoperiod, and is often simulated by reducing thermal-time accumulation using vernalization or photoperiod factors or limiting accumulation when a lower optimum temperature (T(optl)) is exceeded. In this study T(optl) and methods for representing effects of vernalization and photoperiod on anthesis were examined using a range of planting dates and genotypes. METHODS: An examination was made of T(optl) values of 15, 20, 25 and 50 degrees C, and either the most limiting or the multiplicative value of the vernalization and photoperiod development rate factors for simulating anthesis. Field data were from replicated trials at Ludhiana, Punjab, India with July through to December planting dates and seven cultivars varying in vernalization response. KEY RESULTS: Simulations of anthesis were similar for T(optl) values of 20, 25 and 50 degrees C, but a T(optl) of 15 degrees C resulted in a consistent bias towards predicting anthesis late for early planting dates. Results for T(optl) above 15 degrees C may have occurred because mean temperatures rarely exceeded 20 degrees C before anthesis for many planting dates. For cultivars having a strong vernalization response, anthesis was more accurately simulated when vernalization and photoperiod factors were multiplied rather than using the most limiting of the two factors. CONCLUSIONS: Setting T(optl) to a high value (30 degrees C) and multiplying the vernalization and photoperiod factors resulted in accurately simulating anthesis for a wide range of planting dates and genotypes. However, for environments where average temperatures exceed 20 degrees C for much of the pre-anthesis period, a lower T(optl) (23 degrees C) might be appropriate. These results highlight the value of testing a model over a wide range of environments.


Asunto(s)
Modelos Biológicos , Fotoperiodo , Temperatura , Triticum/crecimiento & desarrollo , Productos Agrícolas/crecimiento & desarrollo , Genotipo , India , Estaciones del Año , Factores de Tiempo
5.
J Geophys Res Space Phys ; 123(10): 8850-8864, 2018 Oct.
Artículo en Inglés | MEDLINE | ID: mdl-31008002

RESUMEN

This paper presents measurements of the amplitudes and timings of the combined, annual, and semiannual variations of thermospheric neutral density, and a comparison of these density variations with measurements of the infrared emissions from carbon dioxide and nitric oxide in the thermosphere. The density values were obtained from measurements of the atmospheric drag experienced by the Challenging Minisatellite Payload, Gravity Recovery and Climate Experiment A, Gravity field and Ocean Circulation Explorer, and three Swarm satellites, while the optical emissions were measured with the Sounding of the Atmosphere using Broadband Emission Radiometry (SABER) instrument on the Thermosphere Ionosphere Mesosphere Energetics and Dynamics satellite. These data span a time period of 16 years. A database containing global average densities that were derived from the orbits of about 5,000 objects (Emmert, 2009, https://doi.org/10.1029/2009JA014102, 2015b, https://doi.org/10.1002/2015JA021047) was employed for calibrating these density data. A comparison with the NRLMSISE-00 model was used to derive measurements of how much the density changes over time due to these seasonal variations. It is found that the seasonal density oscillations have significant variations in amplitude and timing. In order to test the practicality of using optical emissions as a monitoring tool, the SABER data were fit to the measured variations. Even the most simple fit that used only filtered carbon dioxide emissions had good correlations with the measured oscillations. However, the density oscillations were also well predicted by a simple Fourier series, contrary to original expectations. Nevertheless, measurements of the optical emissions from the thermosphere are expected to have a role in future understanding and prediction of the semiannual variations.

6.
Biochim Biophys Acta ; 924(1): 175-84, 1987 Apr 16.
Artículo en Inglés | MEDLINE | ID: mdl-3030442

RESUMEN

Because of the extensive oligosaccharide heterogeneity of the membrane glycoprotein (G) from the Hazelhurst strain of vesicular stomatitis virus, this virus has been used as a specific intracellular probe of altered protein glycosylation in Rous sarcoma virus-transformed versus normal baby hamster kidney cells. Over 70% of G protein from virus released from the transformed cells had acidic-type oligosaccharides at both glycosylation sites, compared to less than 50% from the corresponding normal host cells. The remaining G protein contained an acidic-type oligosaccharide at one site and an endo-beta-N-acetylglucosaminidase H-sensitive oligosaccharide at the other. The major endoglycosidase-sensitive species were sialylated hybrid-type (NeuNAc-Gal-GlcNAc-Man5GlcNAc2-Asn) from the transformed and neutral-type (Man5-6GlcNAc2-Asn) from the normal host cells. The degree of branching of the acidic-type oligosaccharides was not increased in the transformed cells (approx. 80% biantennary for viral G protein from both cell types). At a reduced growth temperature (24 versus 37 degrees C), the G protein oligosaccharides were more extensively processed in both cell types (approximately 85-95% of G protein contained acidic-type structures at both sites), even though the level of viral protein synthesis and virus release was decreased. Essentially all of the minor, endoglycosidase-sensitive oligosaccharides on mature viral G protein were sialic acid-containing hybrid-type structures. At 24 degrees C the branching of the acidic-type oligosaccharides was increased in the virus released from the transformed cells versus normal cells.


Asunto(s)
Virus del Sarcoma Aviar/genética , Transformación Celular Neoplásica , Glicoproteínas de Membrana , Oligosacáridos/genética , Virus de la Estomatitis Vesicular Indiana/genética , Proteínas del Envoltorio Viral , Proteínas Virales/genética , Animales , Conformación de Carbohidratos , Secuencia de Carbohidratos , Línea Celular , Cricetinae , Procesamiento Proteico-Postraduccional , Virus de la Estomatitis Vesicular Indiana/metabolismo , Replicación Viral
7.
J Geophys Res Space Phys ; 120(7): 5998-6009, 2015 07.
Artículo en Inglés | MEDLINE | ID: mdl-27668141

RESUMEN

Obtaining accurate predictions of the neutral density in the thermosphere has been a long-standing problem. During geomagnetic storms the auroral heating in the polar ionospheres quickly raises the temperature of the thermosphere, resulting in higher neutral densities that exert a greater drag force on objects in low Earth orbit. Rapid increases and decreases in the temperature and density may occur within a couple days. A key parameter in the thermosphere is the total amount of nitric oxide (NO). The production of NO is accelerated by the auroral heating, and since NO is an efficient radiator of thermal energy, higher concentrations of this molecule accelerate the rate at which the thermosphere cools. This paper describes an improved technique that calculates changes in the global temperature of the thermosphere. Starting from an empirical model of the Poynting flux into the ionosphere, a set of differential equations derives the minimum, global value of the exospheric temperature, which can be used in a neutral density model to calculate the global values. The relative variations in NO content are used to obtain more accurate cooling rates. Comparisons with the global rate of NO emissions that are measured with the Sounding of the Atmosphere using Broadband Emission Radiometry instrument show that there is very good agreement with the predicted values. The NO emissions correlate highly with the total auroral heating that has been integrated over time. We also show that the NO emissions are highly correlated with thermospheric temperature, as well as indices of solar extreme ultraviolet radiation.

8.
FEBS Lett ; 331(1-2): 159-61, 1993 Sep 27.
Artículo en Inglés | MEDLINE | ID: mdl-8405397

RESUMEN

Class III membrane proteins lack cleavable signal peptides but adopt an N-out, C-in topology with respect to their native membranes. We have analysed the fate of two eukaryotic class III plasma membrane proteins, human erythrocyte glycophorin C and influenza A virus M2 protein, in Escherichia coli. The N-terminal domains of both proteins were efficiently localised to the extracytoplasmic side of the bacterial cytoplasmic membrane. When beta-lactamase was fused to the C-terminus of glycophorin C it was localised to the cytoplasm, and protease treatment of spheroplasts caused a reduction in size of the fusion protein consistent with glycophorin C adopting its native topology in E. coli.


Asunto(s)
Escherichia coli/genética , Glicoforinas/metabolismo , Virus de la Influenza A/genética , Proteínas de la Membrana/metabolismo , Proteínas de la Matriz Viral/metabolismo , Secuencia de Bases , Membrana Celular/metabolismo , Clonación Molecular , ADN Complementario , Escherichia coli/metabolismo , Glicoforinas/química , Glicoforinas/genética , Proteínas de la Membrana/química , Proteínas de la Membrana/genética , Datos de Secuencia Molecular , Conformación Proteica , Proteínas de la Matriz Viral/química , Proteínas de la Matriz Viral/genética
9.
Arch Neurol ; 54(6): 707-12, 1997 Jun.
Artículo en Inglés | MEDLINE | ID: mdl-9193205

RESUMEN

OBJECTIVE: To assess the reliability and stability of a standardized road test for healthy aging people and those with dementia of the Alzheimer type (DAT). DESIGN: A prospective study involving patients with DAT and age-matched healthy controls in which subjects' driving performance was evaluated by several raters in an initial and a follow-up road test. SETTING: Urban medical school and urban highways and streets. SUBJECTS: A convenience sample of 58 controls, 36 subjects with very mild DAT, and 29 subjects with mild DAT. RESULTS: Analysis of road test ability of controls (2 subjects [3%] failed the test), very mild DAT subjects (7 subjects [19%] failed), and mild DAT subjects (12 subjects [41%] failed) disclosed a significant association between driving performance and dementia status (chi 2[4] = 20.65 [N = 123]; P < .001; Kendall tau-b = 0.306). Interrater reliability for assessment of driving performance ranged from kappa = 0.85 to 0.96. One-month test-retest stability on the road test was 0.76 (quantitative scoring) and 0.53 (clinical judgment). CONCLUSIONS: Dementia adversely affects driving performance even in its mild stages, although some persons with DAT seem to drive safely for some time after disease onset. A traffic-interactive, performance-based road test that examines cognitive behaviors provides an accurate and reliable functional assessment of driving ability.


Asunto(s)
Enfermedad de Alzheimer/fisiopatología , Enfermedad de Alzheimer/psicología , Conducción de Automóvil , Desempeño Psicomotor , Anciano , Estudios de Casos y Controles , Femenino , Humanos , Masculino , Persona de Mediana Edad , Missouri , Pruebas Neuropsicológicas , Estudios Prospectivos , Valores de Referencia , Reproducibilidad de los Resultados , Índice de Severidad de la Enfermedad
10.
Am J Med ; 66(4): 573-9, 1979 Apr.
Artículo en Inglés | MEDLINE | ID: mdl-433964

RESUMEN

Seven patients with chronic obstructive lung disease (COLD) were monitored during their overnight sleep to determine the occurrence of disordered breathing and oxygen desaturation. Nasal and oral airflows were sensed by thermistor probes, chest wall movement by impedance pneumography and arterial oxygen saturation by ear oximetry. These variables were correlated with electroencephalographic and electrooculographic tracings. The subjects had a mean base line oxygen saturation of 89.2 per cent and slept an average of 218 minutes. Six of these seven subjects had one to 30 episodes of oxygen desaturation (decrease more than 4 per cent), 4 seconds to 30 minutes in duration, with declines in saturation as great as 36 per cent. In two subjects, saturation dropped to less than 50 per cent. Breathing was disordered in five of the seven subjects and included apnea and hypopnea. Subjects experienced from nine to 37 episodes of disordered breathing. Disordered breathing caused 42 per cent of the episodes of desaturation, all of which were less than 1 minute in duration. The mean maximum decline in saturation was 7.6 per cent. All episodes of desaturation lasting longer than 5 minutes occurred in rapid eye movement (REM) sleep and were not caused by disordered breathing. The mean maximal decrease in saturation was 22 per cent. This study reveals that disordered breathing is common in subjects with COLD and often causes desaturation but that it cannot explain all episodes of sleep desaturation.


Asunto(s)
Enfermedades Pulmonares Obstructivas/fisiopatología , Oxígeno/sangre , Respiración , Sueño/fisiología , Adulto , Anciano , Humanos , Enfermedades Pulmonares Obstructivas/complicaciones , Masculino , Persona de Mediana Edad , Trastornos Respiratorios/complicaciones
11.
Viral Immunol ; 13(3): 329-41, 2000.
Artículo en Inglés | MEDLINE | ID: mdl-11016597

RESUMEN

The gB protein (gpUL55) of human cytomegalovirus (CMV) contains C-terminal (AD-1) and N-terminal (AD-2) linear immunodominant neutralizing domains. To measure antibodies to these epitopes, a modified protein (delta-gB) lacking heavily glycosylated intervening regions, the transmembrane domain, and the cytoplasmic domain, was expressed in recombinant baculovirus-infected cells. Eighty-six percent of 600 naturally CMV-seropositive individuals and 93% of 121 gB vaccine recipients had antibodies to delta-gB as detected by enzyme-linked immunosorbent assay (ELISA). The antibody level in vaccinees (median optical density [OD] = 1.73) exceeded that in natural seropositives (median OD = 0.94; p < .0001). Eleven percent of 95 natural seropositives and 7% of 120 gB vaccinees lacked A-gB antibodies but had neutralizing activity. Among subjects with delta-gB antibody, there were weak correlations between antibody level and neutralizing titer. These data suggest that antibodies to linear neutralizing gB domains are highly prevalent in naturally-infected individuals and regularly develop in gB vaccinees. However, for some individuals, discontinuous and/or linear epitopes not represented on delta-gB may be more important in the generation of neutralizing responses.


Asunto(s)
Anticuerpos Antivirales/sangre , Infecciones por Citomegalovirus/inmunología , Vacunas contra Citomegalovirus/inmunología , Citomegalovirus/inmunología , Proteínas del Envoltorio Viral/química , Proteínas del Envoltorio Viral/inmunología , Adulto , Anticuerpos Antivirales/inmunología , Baculoviridae/genética , Infecciones por Citomegalovirus/virología , Ensayo de Inmunoadsorción Enzimática , Humanos , Pruebas de Neutralización , Proteínas Recombinantes/genética , Proteínas Recombinantes/inmunología , Proteínas Recombinantes/metabolismo , Vacunas de Subunidad/inmunología , Proteínas del Envoltorio Viral/genética
12.
Chest ; 76(5): 536-42, 1979 Nov.
Artículo en Inglés | MEDLINE | ID: mdl-498826

RESUMEN

Oxygen desaturation occurs during sleep in some patients with COPD. To investigate the effects of these hypoxemic episodes on the pulmonary vasculature, we studied four patients with our routine polysomnographic techniques and simultaneously recorded pulmonary artery pressure. In all four subjects, nocturnal episodes of desaturation were accompanied by elevations in the pulmonary artery pressure. Low flow oxygen abolished the drops in arterial oxygen saturation (but not the breathing abnormalities) and no elevations in the PA pressure were observed. We postulate that in some COPD patients these initially transient events may lead to sustained pulmonary hypertension and cor pulmonale. Nocturnal oxygen therapy may be indicated in more patients than previously suspected and may prevent the development of cor pulmonale.


Asunto(s)
Hipertensión Pulmonar/etiología , Enfermedades Pulmonares Obstructivas/complicaciones , Sueño , Adulto , Anciano , Presión Sanguínea , Humanos , Hipoxia/etiología , Enfermedades Pulmonares Obstructivas/fisiopatología , Masculino , Persona de Mediana Edad , Oxígeno/fisiología
13.
J Virol Methods ; 4(4-5): 283-95, 1982 May.
Artículo en Inglés | MEDLINE | ID: mdl-6286708

RESUMEN

Glycopeptides and endogly cosidase-digested oligosaccharides from [3H]mannose-labeled Rous sarcoma virus and Sinbis virus have been fractionated by lentil lectin-Sepharose and concanavalin A-agarose affinity chromatography and subsequently analyzed by BioGel P-4 gel filtration. Only a specific subset of the Con A-bound asparaginly-oligosaccharides from he two viruses was also bound to lentil lectin, and this freaction apparently represented fucose-containing, diantennary acidic-type structures ((NeuNAc +/- Gal-GlcNAc)2 Man3 -GlcNAc2 (fucose)-ASN). The largest glycopeptides from Rous sarcoma virus were unbound to either Con A or lentil lectin and presumably contained tri- and/or tetra-antennary acidic-type structures ((NeuNAc +/- Gal-GlcNAc)3--4 -Man 3GlcNAc2 (+/- fucose)-ASN). In contrast, the majority of 'hybrid'-type oligosaccharides and essentially all of the neutral oligomannosyl core structures (Man5--9 GlcNAc1 and Man3 GlcNAc1) from the endoglycosidase-digested glycopeptides of both viruses were specifically bound to Con A-agarose, with the largest neutral oligosaccharides (Man7--9GlcNAc1) bound more tightly and less efficiently eluted by alpha-methyl mannoside.


Asunto(s)
Virus del Sarcoma Aviar/análisis , Glicopéptidos/aislamiento & purificación , Oligosacáridos/aislamiento & purificación , Virus Sindbis/análisis , Proteínas Virales/aislamiento & purificación , Fenómenos Químicos , Química , Cromatografía de Afinidad , Cromatografía en Gel , Lectinas , Sefarosa/análogos & derivados
14.
Toxicology ; 39(3): 259-73, 1986 Jun.
Artículo en Inglés | MEDLINE | ID: mdl-3705088

RESUMEN

Specific alterations in cellular protein synthesis have been identified in mouse L929 and B16 cells exposed to "passive" (sidestream) smoke freshly generated from unfiltered cigarettes. A decrease in both cell viability and protein synthesis was observed in monolayer cell cultures following exposure to increasing numbers (0-12) of puffs of sidestream smoke. With exposures that resulted in approximately 30% or higher loss in cell viability, there was an apparent induction of cell stress/heat shock-like polypeptides with approximate molecular weights of 88,000, 66,000 and 23,000. After exposure to higher numbers of puffs that led to a loss of cell viability of 80% or greater, a different set of polypeptides was synthesized, including a major new protein of 38,000 mol. wt and 2 other predominant proteins of 45,000 and 30,000 mol. wt. The same specific effects on cellular protein synthesis were also observed after exposure to a similar number of puffs of the gas phase of sidestream cigarette smoke (minus the particulate phase components).


Asunto(s)
Proteínas de Choque Térmico/biosíntesis , Contaminación por Humo de Tabaco/efectos adversos , Animales , Línea Celular , Supervivencia Celular/efectos de los fármacos , Electroforesis en Gel de Poliacrilamida , Gases , Células L , Leucina/metabolismo , Melanoma , Ratones , Peso Molecular , Péptidos/análisis
15.
Clin Geriatr Med ; 9(2): 439-48, 1993 May.
Artículo en Inglés | MEDLINE | ID: mdl-8504390

RESUMEN

Although many individuals who have had strokes or other physical problems assume that they can no longer drive, they are often unaware of retraining programs. In addition to formal courses supported by sponsoring agencies, such as the AAA, there are also programs run by occupational therapists. This article addresses issues relevant to the role of occupational therapists in evaluation and retraining of older drivers and describes several cases as examples. To better inform the public about driver retraining programs for the elderly and the disabled population, the American Occupational Therapy Association has published a pamphlet entitled Able Driving Is Safe Driving that provides information on how driving skills may be affected by age or illness. This publication also will provide examples of adaptive driving equipment usage and driver training. AOTA hopes this pamphlet will inform older adults of their options in maintaining independent community mobility. Research is needed to find out if older adults have relinquished driving because of a physical disability that may have been treatable with rehabilitation. Also, there needs to be a comparison study of classroom driving instruction to actual skill performance so that older adults and insurance companies are investing in programs that will demonstrate the outcome of improved driving performance.


Asunto(s)
Anciano , Conducción de Automóvil , Conducción de Automóvil/educación , Automóviles , Personas con Discapacidad , Femenino , Humanos , Masculino , Persona de Mediana Edad , Terapia Ocupacional , Aptitud Física
16.
Phys Med Biol ; 58(11): 3599-613, 2013 Jun 07.
Artículo en Inglés | MEDLINE | ID: mdl-23640172

RESUMEN

The electrical conductivity of small samples of mouse cortex (in vitro) has been measured at 10 kHz through the four-electrode method of van der Pauw. Brain slices from three mice were prepared under seizing and non-seizing conditions by changing the concentration of magnesium in the artificial cerebrospinal fluid used to maintain the tissue. These slices provided 121 square samples of cortical tissue; the conductivity of these samples was measured with an Agilent E4980A four-point impedance monitor. Of these, 73 samples were considered acceptable on the grounds of having good electrical contact between electrodes and tissue excluding outlier measurements. Results show that there is a significant difference (p = 0.03) in the conductivities of the samples under the two conditions. The seizing and non-seizing samples have mean conductivities of 0.33 and 0.36 S m(-1), respectively; however, these quantitative values should be used with caution as they are both subject to similar systematic uncertainties due to non-ideal temperature conditions and non-ideal placement of electrodes. We hypothesize that the difference between them, which is more robust to uncertainty, is due to the changing gap junction connectivity during seizures.


Asunto(s)
Encéfalo/patología , Conductividad Eléctrica , Convulsiones/patología , Animales , Femenino , Uniones Comunicantes/metabolismo , Ratones , Ratones Endogámicos C57BL
19.
J Virol ; 35(2): 362-70, 1980 Aug.
Artículo en Inglés | MEDLINE | ID: mdl-6255177

RESUMEN

To determine the particular intracellular steps in the glycosylation of the vesicular stomatitis virus (VSV) glycoprotein that were altered in several lectin-resistant CHO cell lines, VSV-infected parental and mutant cells were pulse-labeled for 30 and 120 min with [3H]mannose and [3H]glucosamine. Cell-associated viral glycopeptides were analyzed by gel filtration combined with specific glycosidase digestions and compared with the corresponding mature virion oligosaccharides. The intracellular glycosylation of the VSV glycoprotein in a mutant cell line resistant to phytohemagglutinin was identical to that in the normal cells except for a complete block in processing at a specific step in the final trimming of the oligomannosyl core from five to three mannoses. The results demonstrated that a double-mutant cell line selected from the phytohemagglutinin-resistant cells for resistance to concanavalin A had an additional defect in one of the earliest stages of glycosylation, resulting in smaller precursor oligosaccharides linked to protein.


Asunto(s)
Glicoproteínas/biosíntesis , Oligosacáridos/biosíntesis , Virus de la Estomatitis Vesicular Indiana/metabolismo , Proteínas Virales/biosíntesis , Animales , Línea Celular , Cromatografía en Gel , Concanavalina A/farmacología , Cricetinae , Resistencia a Medicamentos , Femenino , Mutación , Ovario , Fitohemaglutininas/farmacología
20.
Cell ; 21(2): 407-15, 1980 Sep.
Artículo en Inglés | MEDLINE | ID: mdl-7407919

RESUMEN

The lipid-linked and asparagine-linked oligosaccharides of two lectin-resistant and one parental Chinese hamster ovary (CHO) cell line have been compared by glycosidase digestion and gel filtration analysis of radiolabeled glycopeptides and oligosaccharides. The additional glycosylation defect in a double mutant cell line (CHO-PhaRConAR) selected from a phytohemagglutinin-resistant single mutant cell line (CHO-PhaR) for resistance to concanavalin A has been identified as a block in the synthesis of the lipid-linked oligosaccharide precursor, resulting in a structure with seven instead of the normal nine mannose units. Both the CHO-PhaRConR and CHO-PhaR cells were completely blocked in the synthesis of complex, acidic type oligosaccharides because of a previously demonstrated deficiency in a particular N--acetylglucosamine transferase activity. In addition, an altered collection of neutral type oligosaccharides (Man4-7GlcNAc2) accumulated in the glycoproteins of the double mutant.


Asunto(s)
Concanavalina A/farmacología , Lectinas/farmacología , Oligosacáridos/metabolismo , Proteínas/metabolismo , Animales , Asparagina , Conformación de Carbohidratos , Línea Celular , Cricetinae , Resistencia a Medicamentos , Femenino , Mutación , Oligosacáridos/análisis , Ovario
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