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1.
Sci Eng Ethics ; 26(3): 1477-1498, 2020 06.
Artículo en Inglés | MEDLINE | ID: mdl-31970596

RESUMEN

Bainbridge's well known "Ironies of Automation" (in: Johannsen, Rijnsdorp (eds) Analysis, design and evaluation of man-machine systems. Elsevier, Amsterdam, pp 129-135, 1983. https://doi.org/10.1016/B978-0-08-029348-6.50026-9) laid out a set of fundamental criticisms surrounding the promises of automation that, even 30 years later, remain both relevant and, in many cases, intractable. Similarly, a set of ironies in technologies for sensor driven self-quantification (often referred to broadly as wearables) is laid out here, spanning from instrumental problems in human factors design (such as disagreement over physiological norms) to much broader social problems (such as loss of freedom). As with automation, these ironies stand in the way of many of the promised benefits of these wearable technologies. It is argued here that without addressing these ironies now, the promises of wearables may not come to fruition, and instead users may experience outcomes that are opposite to those which the designers seek to afford, or, at the very least, those which consumers believe they are being offered. This paper describes four key ironies of sensor driven self-quantification: (1) know more, know better versus no more, no better; (2) greater self-control versus greater social control; (3) well-being versus never being well enough; (4) more choice versus erosion of choice.


Asunto(s)
Dispositivos Electrónicos Vestibles , Humanos
2.
Metabolomics ; 14(8): 105, 2018 08 03.
Artículo en Inglés | MEDLINE | ID: mdl-30830422

RESUMEN

INTRODUCTION: Melanoma is a highly aggressive malignancy and is currently one of the fastest growing cancers worldwide. While early stage (I and II) disease is highly curable with excellent prognosis, mortality rates rise dramatically after distant spread. We sought to identify differences in the metabolome of melanoma patients to further elucidate the pathophysiology of melanoma and identify potential biomarkers to aid in earlier detection of recurrence. METHODS: Using 1H NMR and DI-LC-MS/MS, we profiled serum samples from 26 patients with stage III (nodal metastasis) or stage IV (distant metastasis) melanoma and compared their biochemical profiles with 46 age- and gender-matched controls. RESULTS: We accurately quantified 181 metabolites in serum using a combination of 1H NMR and DI-LC-MS/MS. We observed significant separation between cases and controls in the PLS-DA scores plot (permutation test p-value = 0.002). Using the concentrations of PC-aa-C40:3, DL-carnitine, octanoyl-L-carnitine, ethanol, and methylmalonyl-L-carnitine we developed a diagnostic algorithm with an AUC (95% CI) = 0.822 (0.665-0.979) with sensitivity and specificity of 100 and 56%, respectively. Furthermore, we identified arginine, proline, tryptophan, glutamine, glutamate, glutathione and ornithine metabolism to be significantly perturbed due to disease (p < 0.05). CONCLUSION: Targeted metabolomic analysis demonstrated significant differences in metabolic profiles of advanced stage (III and IV) melanoma patients as compared to controls. These differences may represent a potential avenue for the development of multi-marker serum-based assays for earlier detection of recurrences, allow for newer, more effective targeted therapy when tumor burden is less, and further elucidate the pathophysiologic changes that occur in melanoma.


Asunto(s)
Biomarcadores de Tumor/sangre , Melanoma/diagnóstico , Metaboloma , Suero/metabolismo , Anciano , Estudios de Casos y Controles , Cromatografía Liquida/métodos , Estudios de Cohortes , Femenino , Humanos , Metástasis Linfática , Masculino , Melanoma/metabolismo , Persona de Mediana Edad , Pronóstico , Curva ROC , Espectrometría de Masas en Tándem/métodos
3.
Int J Obes (Lond) ; 40(7): 1183-6, 2016 07.
Artículo en Inglés | MEDLINE | ID: mdl-26975440

RESUMEN

Binge-eating behavior involves rapid consumption of highly palatable foods leading to increased weight gain. Feeding in binge disorders resembles other compulsive behaviors, many of which are responsive to N-acetylcysteine (NAC), which is a cysteine prodrug often used to promote non-vesicular glutamate release by a cystine-glutamate antiporter. To examine the potential for NAC to alter a form of compulsive eating, we examined the impact of NAC on binge eating in a rodent model. Specifically, we monitored consumption of standard chow and a high-fat, high carbohydrate western diet (WD) in a rodent limited-access binge paradigm. Before each session, rats received either a systemic or intraventricular injection of NAC. Both systemic and central administration of NAC resulted in significant reductions of binge eating the WD without decreasing standard chow consumption. The reduction in WD was not attributable to general malaise as NAC did not produce condition taste aversion. These results are consistent with the clinical evidence of NAC to reduce or reverse compulsive behaviors, such as, drug addiction, skin picking and hair pulling.


Asunto(s)
Acetilcisteína/farmacología , Trastorno por Atracón/tratamiento farmacológico , Modelos Animales de Enfermedad , Conducta Alimentaria/efectos de los fármacos , Conducta Alimentaria/psicología , Animales , Condicionamiento Operante/efectos de los fármacos , Dieta Alta en Grasa , Inyecciones Intraventriculares , Masculino , Ratas , Ratas Sprague-Dawley
4.
Sci Eng Ethics ; 22(1): 93-110, 2016 Feb.
Artículo en Inglés | MEDLINE | ID: mdl-25649071

RESUMEN

Objections to the use of assistive technologies (such as prostheses) in elite sports are generally raised when the technology in question is perceived to afford the user a potentially "unfair advantage," when it is perceived as a threat to the purity of the sport, and/or when it is perceived as a precursor to a slippery slope toward undesirable changes in the sport. These objections rely on being able to quantify standards of "normal" within a sport so that changes attributed to the use of assistive technology can be judged as causing a significant deviation from some baseline standard. This holds athletes using assistive technologies accountable to standards that restrict their opportunities to achieve greatness, while athletes who do not use assistive technologies are able to push beyond the boundaries of these standards without moral scrutiny. This paper explores how constructions of fairness and "normality" impact athletes who use assistive technology to compete in a sporting venue traditionally populated with "able-bodied" competitors. It argues that the dynamic and obfuscated construction of "normal" standards in elite sports should move away from using body performance as the measuring stick of "normal," toward alternate forms of constructing norms such as defining, quantifying, and regulating the mechanical actions that constitute the critical components of a sport. Though framed within the context of elite sports, this paper can be interpreted more broadly to consider problems with defining "normal" bodies in a society in which technologies are constantly changing our abilities and expectations of what normal means.


Asunto(s)
Personas con Discapacidad , Dispositivos de Autoayuda/ética , Justicia Social , Normas Sociales , Deportes/ética , Atletas , Humanos , Principios Morales
5.
PLoS One ; 18(7): e0289017, 2023.
Artículo en Inglés | MEDLINE | ID: mdl-37486889

RESUMEN

Automation inherently removes a certain amount of user control. If perceived as a loss of freedom, users may experience psychological reactance, which is a motivational state that can lead a person to engage in behaviors to reassert their freedom. In an online experiment, participants set up and communicated with a hypothetical smart thermostat. Participants read notifications about a change in the thermostat's setting. Phrasing of notifications was altered across three dimensions: strength of authoritative language, deviation of temperature change from preferences, and whether or not the reason for the change was transparent. Authoritative language, temperatures outside the user's preferences, and lack of transparency induced significantly higher levels of reactance. However, when the system presented a temperature change outside of the user's preferences, reactance was mitigated and user acceptance was higher if the thermostat's operations were transparent. Providing justification may be less likely to induce psychological reactance and increase user acceptance. This supports efforts to use behavioral approaches, such as demand response, to increase sustainability and limit the impacts of climate change.


Asunto(s)
Automatización , Temperatura , Humanos , Cambio Climático , Lenguaje , Motivación
6.
J Nanosci Nanotechnol ; 9(5): 2917-22, 2009 May.
Artículo en Inglés | MEDLINE | ID: mdl-19452949

RESUMEN

Electrically conductive nanocomposites from cellulose nanofibrils (CNF) were successfully produced by in situ polymerization of aniline onto CNF, and studied by open circuit potential (Voc), four probe direct current (dc) electrical conductivity, ultraviolet-visible (UV-Vis) spectroscopy and scanning electron microscopy (SEM). The oxidative polymerization of aniline using ammonium peroxydisulfate in hydrochloric acid aqueous solutions was realized by the addition of nanofibrils leading to an aqueous suspension of CNF coated with polyaniline (PANI). This procedure lead to stable, green suspensions of CNF coated with PANI in the emeraldine oxidation state as demonstrated by Voc and UV-Vis analyses. Electrically conductive films of this cellulose nanocomposite could be cast from aqueous solutions with conductivity close to the conducting polymer, yet with the potential for more useful flexible films.


Asunto(s)
Compuestos de Anilina/química , Celulosa/química , Conductividad Eléctrica , Nanocompuestos/química , Compuestos de Anilina/síntesis química , Celulosa/síntesis química , Microscopía Electrónica de Rastreo , Nanocompuestos/ultraestructura , Nanoestructuras/química , Nanoestructuras/ultraestructura , Espectrofotometría Ultravioleta
7.
Neuroscience ; 155(2): 530-7, 2008 Aug 13.
Artículo en Inglés | MEDLINE | ID: mdl-18601982

RESUMEN

Repeated cocaine alters glutamate neurotransmission, in part, by reducing cystine-glutamate exchange via system xc-, which maintains glutamate levels and receptor stimulation in the extrasynaptic compartment. In the present study, we undertook two approaches to determine the significance of plasticity involving system xc-. First, we examined whether the cysteine prodrug N-acetylcysteine attenuates cocaine-primed reinstatement by targeting system xc-. Rats were trained to self-administer cocaine (1 mg/kg/200 microl, i.v.) under extended access conditions (6 h/day). After extinction training, cocaine (10 mg/kg, i.p.) primed reinstatement was assessed in rats pretreated with N-acetylcysteine (0-60 mg/kg, i.p.) in the presence or absence of the system xc- inhibitor (S)-4-carboxyphenylglycine (CPG; 0.5 microM; infused into the nucleus accumbens). N-acetylcysteine attenuated cocaine-primed reinstatement, and this effect was reversed by co-administration of CPG. Secondly, we examined whether reduced system xc- activity is necessary for cocaine-primed reinstatement. To do this, we administered N-acetylcysteine (0 or 90 mg/kg, i.p.) prior to 12 daily self-administration sessions (1 mg/kg/200 microl, i.v.; 6 h/day) since this procedure has previously been shown to prevent reduced activity of system xc-. On the reinstatement test day, we then acutely impaired system xc- in some of the rats by infusing CPG (0.5 microM) into the nucleus accumbens. Rats that had received N-acetylcysteine prior to daily self-administration sessions exhibited diminished cocaine-primed reinstatement; this effect was reversed by infusing the cystine-glutamate exchange inhibitor CPG into the nucleus accumbens. Collectively these data establish system xc- in the nucleus accumbens as a key mechanism contributing to cocaine-primed reinstatement.


Asunto(s)
Antiportadores/metabolismo , Trastornos Relacionados con Cocaína/metabolismo , Cistina/metabolismo , Ácido Glutámico/metabolismo , Núcleo Accumbens/metabolismo , Animales , Conducta Animal/efectos de los fármacos , Cocaína/farmacología , Trastornos Relacionados con Cocaína/fisiopatología , Cistina/análogos & derivados , Cistina/farmacología , Inhibidores de Captación de Dopamina/farmacología , Extinción Psicológica/efectos de los fármacos , Masculino , Microdiálisis , Núcleo Accumbens/efectos de los fármacos , Ratas , Ratas Sprague-Dawley , Autoadministración , Sinapsis/metabolismo
8.
Public Underst Sci ; 26(2): 251-258, 2017 02.
Artículo en Inglés | MEDLINE | ID: mdl-26386020

RESUMEN

Both academic and legal communities have cautioned that laypersons may be unduly persuaded by images of the brain and may fail to interpret them appropriately. While early studies confirmed this concern, a second wave of research was repeatedly unable to find evidence of such a bias. The newest wave of studies paints a more nuanced picture in which, under certain circumstances, a neuroimage bias reemerges. To help make sense of this discordant body of research, we highlight the contextual significance of understanding how laypersons' decision making is or is not impacted by neuroimages, provide an overview of findings from all sides of the neuroimage bias question, and discuss what these findings mean to public use and understanding of neuroimages.


Asunto(s)
Comprensión , Toma de Decisiones , Neuroimagen , Encéfalo/diagnóstico por imagen , Humanos , Jurisprudencia , Variaciones Dependientes del Observador
9.
Genes Brain Behav ; 5(3): 222-39, 2006 Apr.
Artículo en Inglés | MEDLINE | ID: mdl-16594976

RESUMEN

Perception of the earth's gravitational force is essential for most forms of animal life. However, little is known of the molecular mechanisms and neuronal circuitry underlying gravitational responses. A forward genetic screen using Drosophila melanogaster that provides insight into these characteristics is described here. Vertical choice mazes combined with additional behavioral assays were used to identify mutants specifically affected in gravitaxic responses. Twenty-three mutants were selected for molecular analysis. As a result, 18 candidate genes are now implicated in the gravitaxic behavior of flies. Many of these genes have orthologs across the animal kingdom, while some are more specific to Drosophila and invertebrates. One gene (yuri) located close to a known locus for gravitaxis has been the subject of more extensive analysis including confirmation by transgenic rescue.


Asunto(s)
Proteínas de Drosophila/genética , Drosophila melanogaster/genética , Sensación de Gravedad/fisiología , Aprendizaje por Laberinto/fisiología , Mutación/genética , Análisis de Varianza , Animales , Animales Modificados Genéticamente , Secuencia de Bases , Drosophila melanogaster/fisiología , Pruebas Genéticas , Humanos , Masculino , Datos de Secuencia Molecular , Polimorfismo Genético/genética , Órganos de los Sentidos/fisiología , Factores de Transcripción/genética
10.
Oncogene ; 11(7): 1347-56, 1995 Oct 05.
Artículo en Inglés | MEDLINE | ID: mdl-7478556

RESUMEN

FDC-P1 haemopoietic cells were used to select mutations of c-fms that constitutively activate the receptor for macrophage-colony stimulating factor (M-CSF or CSF-1). One mutation changed Ser 929 to Gly within a Ser/Gly rich region of the C-terminal tail and a second changed a nearby, highly conserved Leu 926 for Pro. A third mutation (D802V) changed Asp 802 to Val within the alpha L12/beta 9 region of the tyrosine kinase domain, so supporting the crystallographic evidence that this region triggers kinase activation. A c-kit mutation exactly equivalent to D802V was previously identified in a leukamic cell line and was demonstrated here to be transforming. Surprisingly, although D802V potently transformed FDC-P1 cells, it could not induce Rat-2 fibroblast foci, even in the presence of M-CSF. It is suggested that the accelerated receptor degradation induced by D802V may account for its cell specific effect.


Asunto(s)
Mutación , Receptor de Factor Estimulante de Colonias de Macrófagos/genética , Secuencia de Aminoácidos , Animales , Secuencia de Bases , División Celular/genética , Transformación Celular Neoplásica , ADN Complementario , Células Madre Hematopoyéticas/citología , Humanos , Factor Estimulante de Colonias de Macrófagos/farmacología , Ratones , Datos de Secuencia Molecular , Oligodesoxirribonucleótidos , Fosforilación , Proteínas Tirosina Quinasas/metabolismo , Proteínas Proto-Oncogénicas c-kit/metabolismo , Receptor de Factor Estimulante de Colonias de Macrófagos/metabolismo , Receptores de Superficie Celular/efectos de los fármacos , Receptores de Superficie Celular/metabolismo , Alineación de Secuencia , Factor de Células Madre/genética
11.
Oncogene ; 11(8): 1639-47, 1995 Oct 19.
Artículo en Inglés | MEDLINE | ID: mdl-7478589

RESUMEN

Although Ras plays a fundamental role in cellular proliferation, differentiation and transformation, clear functional differences between the three major Ras proteins (N-, H- and K-Ras) have not as yet been demonstrated. In this study, chimeric constructs were used to compare directly transformation by N-, H- and K-ras oncogenes. In Rat-2 and NIH3T3 fibroblasts, transformation assays (anchorage independence, focus-formation and growth in 1% FCS) showed that H12-Ras was more transforming than N12-Ras or K12-Ras. By contrast, in the human multipotent haemopoietic cell line, TF-1, N12-Ras exhibited greater biological activity. Northern blotting and protein analyses indicated that these findings were not the result of differences in expression or stability of p21Ras. Using further H-ras/N-ras chimeric constructs, we found that the greater transforming activity of H12-Ras in fibroblasts was not due to the hypervariable-CAAX region, but rather to unique sequences between amino acids 84 and 143. These data demonstrate cell specific differences in the intrinsic transforming potential of N-ras, H-ras and K-ras oncogenes.


Asunto(s)
Transformación Celular Neoplásica/genética , Animales , Secuencia de Bases , Adhesión Celular , División Celular , Células Cultivadas , Cartilla de ADN/química , Fibroblastos/citología , Expresión Génica , Genes ras , Células Madre Hematopoyéticas/citología , Humanos , Datos de Secuencia Molecular , Oncogenes , Mutación Puntual , ARN Mensajero/genética , Ratas
12.
J Neurosci ; 21(22): 9043-52, 2001 Nov 15.
Artículo en Inglés | MEDLINE | ID: mdl-11698615

RESUMEN

The present study aimed to characterize a functional role for group I metabotropic glutamate receptors (mGluRs) in the nucleus accumbens and the capacity of repeated cocaine to elicit long-term changes in group I mGluR function. Reverse dialysis of the group I agonist (RS)-3,5-dihydroxyphenylglycine (DHPG) into the nucleus accumbens resulted in an increase in extracellular glutamate levels that was mediated by the mGluR1 subtype and depended on voltage-dependent Na(+) and Ca(2+) conductance. At 3 weeks after discontinuing 1 week of daily cocaine injections, the capacity of DHPG to induce glutamate release was markedly reduced. Similarly, DHPG induced an mGluR1-dependent increase in locomotor activity after microinjection into the nucleus accumbens that was significantly blunted 3 weeks after repeated cocaine administration. Signaling through group I mGluRs is regulated, in part, by Homer proteins, and it was found that the blunting of group I mGluR-induced glutamate release and motor activity after repeated cocaine was associated with a reduction in Homer1b/c protein that was selective for the medial nucleus accumbens. These data show that repeated cocaine produces an enduring inhibition of the neurochemical and behavioral consequences of stimulating mGluR1 that is accompanied by changes in the mGluR scaffolding apparatus.


Asunto(s)
Proteínas Portadoras/metabolismo , Cocaína/administración & dosificación , Ácido Glutámico/metabolismo , Neuropéptidos/metabolismo , Núcleo Accumbens/efectos de los fármacos , Núcleo Accumbens/metabolismo , Receptores de Glutamato Metabotrópico/metabolismo , Animales , Química Encefálica/efectos de los fármacos , Bloqueadores de los Canales de Calcio/farmacología , Esquema de Medicación , Tolerancia a Medicamentos , Agonistas de Aminoácidos Excitadores/farmacología , Antagonistas de Aminoácidos Excitadores/farmacología , Espacio Extracelular/química , Espacio Extracelular/metabolismo , Glicina/análogos & derivados , Glicina/farmacología , Proteínas de Andamiaje Homer , Masculino , Microdiálisis , Actividad Motora/efectos de los fármacos , Ratas , Ratas Endogámicas , Ratas Sprague-Dawley , Receptor del Glutamato Metabotropico 5 , Receptores AMPA/metabolismo , Receptores de Glutamato Metabotrópico/agonistas , Receptores de Glutamato Metabotrópico/antagonistas & inhibidores , Resorcinoles/farmacología , Tetrodotoxina/administración & dosificación
13.
J Neurosci ; 20(2): 798-805, 2000 Jan 15.
Artículo en Inglés | MEDLINE | ID: mdl-10632609

RESUMEN

To examine neuronal activation associated with incentive motivation for cocaine, cocaine-seeking behavior (operant responding without cocaine reinforcement) and Fos expression were examined in rats exposed to saline and cocaine priming injections and/or a self-administration environment. Rats were first trained to self-administer cocaine or received yoked saline administration ("control"). They then received 21 daily exposures to either the self-administration environment ("extinction") or a different environment ("no extinction") without cocaine available. Extinction training, used to decrease incentive motivation for cocaine elicited by the self-administration environment, decreased cocaine-seeking behavior elicited by both the environment and the cocaine priming injection. Exposure to the self-administration environment enhanced Fos expression in the no extinction group relative to control and extinction groups in the anterior cingulate, basolateral amygdala, hippocampal CA1 region, dentate gyrus, nucleus accumbens shell and core, and central gray area, regardless of whether or not priming injections were given. The priming injections enhanced Fos expression in the ventral tegmental area, caudate putamen, substantia nigra pars reticulata, entorhinal cortex, central amygdala, lateral amygdala, arcuate nucleus, and central gray area, regardless of group. Thus, these changes likely reflect an unconditioned effect from either cocaine or injection stress. The priming injections also enhanced Fos expression in the anterior cingulate, but only in cocaine-experienced groups, suggesting that this enhancement reflects an experience-dependent motivational effect of the priming injections. The results suggest that different neural circuits may be involved in the incentive motivational effects of cocaine-paired environmental stimuli versus priming injections and that the anterior cingulate may be part of a common pathway for both.


Asunto(s)
Encéfalo/metabolismo , Trastornos Relacionados con Cocaína/metabolismo , Trastornos Relacionados con Cocaína/psicología , Cocaína/administración & dosificación , Neuronas/metabolismo , Proteínas Proto-Oncogénicas c-fos/genética , Animales , Condicionamiento Operante , Extinción Psicológica , Regulación de la Expresión Génica , Masculino , Especificidad de Órganos , Células Piramidales/metabolismo , Ratas , Ratas Sprague-Dawley , Refuerzo en Psicología , Autoadministración , Factores de Tiempo
14.
Biochim Biophys Acta ; 1491(1-3): 341-9, 2000 Apr 25.
Artículo en Inglés | MEDLINE | ID: mdl-10760601

RESUMEN

A third calcium-dependent protein kinase (CDPK) gene has been isolated from the human malaria parasite Plasmodium falciparum by vectorette technology. The gene consists of five exons and four introns. The open reading frame resulting from removal of the four introns encodes a protein of 562 amino acid residues with a predicted molecular mass of 65.3 kDa. The encoded protein, termed PfCDPK3, consists of four distinct domains characteristic of a member of the CDPK family and displays the highest homology (46% identity and 69% similarity) to PfCDPK2, the second CDPK of P. falciparum. The N-terminal variable domain is rich in serine/threonine and lysine and contains multiple consensus phosphorylation sites for a range of protein kinases. The catalytic domain possesses all conserved motifs of the protein kinase family except for the highly conserved glutamic acid residue in subdomain VIII, which is replaced by a glutamine residue. The sequence of the junction domain comprising 31 amino acid residues is less conserved. The calmodulin-like regulatory domain contains four EF-hand calcium-binding motifs, each consisting of a loop of 12 amino acid residues which is flanked by two alpha-helices. Southern blotting of genomic DNA digests showed that the Pfcdpk3 gene is present as a single copy per haploid genome. A 2900 nucleotide transcript of this gene is expressed specifically in the sexual erythrocytic stage, indicating that PfCDPK3 is involved in sexual stage-specific events. It is proposed that PfCDPK3 may serve as a link between calcium and gametogenesis of P. falciparum.


Asunto(s)
Proteínas de Unión al Calcio/genética , Genes Protozoarios , Plasmodium falciparum/enzimología , Proteínas Quinasas/genética , Proteínas Protozoarias , Secuencia de Aminoácidos , Animales , Secuencia de Bases , Proteínas de Unión al Calcio/química , Clonación Molecular , Gametogénesis , Isoenzimas/genética , Datos de Secuencia Molecular , Plasmodium falciparum/genética , Proteínas Quinasas/química , Proteínas Quinasas/metabolismo , ARN/análisis , Mapeo Restrictivo , Alineación de Secuencia
15.
J Mol Biol ; 204(3): 789-95, 1988 Dec 05.
Artículo en Inglés | MEDLINE | ID: mdl-3225852

RESUMEN

The parasitic flagellate Giardia is the source of a filamentous protein, giardin, which binds to microtubules. The primary sequence of one giardin chain has been decoded from the base sequences of cDNAs isolated by antibody screens of a library constructed in the expression vector lambda gt11. The amino acid sequence favours a continuous alpha-helical fold for the protein without any inserts of a non-helical character. Analysis of apolar residue positions revealed 35 repeating heptads consistent with coiled-coil structure. This conformation relates giardin to the alpha-type fibrous proteins (k-m-e-f class) like tropomyosin and myosin (also found in Giardia). The giardin sequence has a regular series of skip residues like those at certain positions in the rod section of nematode myosin where the internal apolar seam of the coiled coil is shifted on the helix surface. The skips divide the giardin coil into quasi-equivalent structural segments about 4 nm in length, which might be domains for combining with tubulin subunits in the microtubule surface lattice.


Asunto(s)
Proteínas del Citoesqueleto , Giardia/metabolismo , Proteínas Protozoarias , Secuencia de Aminoácidos , Animales , Microtúbulos/metabolismo , Datos de Secuencia Molecular , Conformación Proteica
16.
Leukemia ; 8(11): 1970-81, 1994 Nov.
Artículo en Inglés | MEDLINE | ID: mdl-7526094

RESUMEN

We previously reported that M-CSF could mimic the synergistic effect of SCF upon myeloid FDC-P1 cells that were first infected with a c-fms retrovirus, which encodes the human M-CSFr. We now report that an M-CSFr with a mutation of its autophosphorylation site at position 809 was, in response to M-CSF, unable both to synergize with IL-3 or GM-CSF and to induce c-myc; whereas a mutant receptor with a deletion of its kinase insert was unaffected for these processes. The expression of an exogenous c-myc proto-oncogene or a 12H-ras oncogene lowered the requirement of FDC-P1 cells for IL-3 or GM-CSF, in a similar manner to M-CSF or SCF addition. Furthermore, the expression of either of these genes complemented the defective M-CSFr F809. These results strongly support a role for ras and myc in the synergistic action of M-CSF and, by implication, of SCF, which implies that these signalling intermediates are rate-limiting for the action of IL-3 and GM-CSF and possibly other haemopoietic growth factors.


Asunto(s)
Genes myc , Genes ras , Sustancias de Crecimiento/farmacología , Factores de Crecimiento de Célula Hematopoyética/administración & dosificación , Factor Estimulante de Colonias de Macrófagos/administración & dosificación , Animales , Secuencia de Bases , División Celular/efectos de los fármacos , Línea Celular , Expresión Génica , Datos de Secuencia Molecular , Oligodesoxirribonucleótidos/química , Fosfotirosina , Proto-Oncogenes Mas , ARN Mensajero/genética , Ratas , Proteínas Tirosina Quinasas Receptoras/metabolismo , Transducción de Señal , Factor de Células Madre , Relación Estructura-Actividad , Tirosina/análogos & derivados , Tirosina/metabolismo
17.
Leukemia ; 8(1): 141-50, 1994 Jan.
Artículo en Inglés | MEDLINE | ID: mdl-7507191

RESUMEN

Stem cell factor (SCF) was found to stimulate the growth of the haemopoietic cell line FDC-P1 in synergy with either interleukin 3 (IL-3) or granulocyte-macrophage-colony stimulating factor (GM-CSF). Similarly, macrophage colony-stimulating factor (M-CSF) was shown to synergize with IL-3 or GM-CSF, following the infection of FDC-P1 cells with a recombinant retrovirus which encoded the receptor for M-CSF (M-CSFr). These results raise the possibility that signal transduction pathways which are controlled by SCF in FDC-P1 cells, can be activated by M-CSF if its receptor is illicitly expressed. FDC-P1 cells that expressed the M-CSFr were responsive to as little as 100 U/ml of M-CSF when added in combination with IL-3 or GM-CSF. This sensitive assay was used to demonstrate that transforming deletions of the C-terminal tail of the M-CSFr and two-point mutations within the same region that converted tyrosine 969 to either phenylalanine or to cysteine, allowed the mutant M-CSF receptors to synergize with IL-3 or GM-CSF in the absence of M-CSF. These mutations were found to be more evidently transforming in FDC-P1 cells than in Rat-2 fibroblasts. The possible relevance of these results to leukaemia and to gynaecological malignancies is discussed.


Asunto(s)
Transformación Celular Neoplásica/genética , Genes fms/genética , Factor Estimulante de Colonias de Granulocitos y Macrófagos/farmacología , Factores de Crecimiento de Célula Hematopoyética/farmacología , Células Madre Hematopoyéticas/efectos de los fármacos , Interleucina-3/farmacología , Factor Estimulante de Colonias de Macrófagos/farmacología , Mutación/genética , Secuencia de Aminoácidos , Animales , Southern Blotting , División Celular/efectos de los fármacos , Línea Celular , Transformación Celular Neoplásica/efectos de los fármacos , Sinergismo Farmacológico , Fibroblastos/citología , Fibroblastos/efectos de los fármacos , Expresión Génica/genética , Células Madre Hematopoyéticas/citología , Células Madre Hematopoyéticas/metabolismo , Humanos , Ratones , Datos de Secuencia Molecular , Ratas , Retroviridae/genética , Infecciones por Retroviridae/genética , Sensibilidad y Especificidad , Factor de Células Madre , Estimulación Química
18.
Neuropsychopharmacology ; 19(1): 48-59, 1998 Jul.
Artículo en Inglés | MEDLINE | ID: mdl-9608576

RESUMEN

Cocaine and cocaine-associated cues elicit craving in addicts and reinstate cocaine-seeking behavior in rats. Craving and cocaine-seeking behavior may be mediated by withdrawal-induced changes in dopamine (DA) neurotransmission in the amygdala. To examine whether there are concomittant changes in cocaine-seeking behavior and extracellular DA levels during withdrawal, experimental rats were trained to self-administer cocaine (0.75 mg/kg i.v.). After 14 daily 3-hour training sessions, animals underwent either a 1-day, 1-week, or 1-month withdrawal period. Extracellular DA levels were assessed during baseline, extinction, cue reinstatement, and cocaine (15 mg/kg i.p.) reinstatement of cocaine-seeking behavior (i.e., defined as the difference in nonreinforced lever presses on an active minus inactive lever). Cocaine-seeking behavior became more intense during the course of cocaine withdrawal. Additionally, basal and cocaine-induced extracellular DA levels were enhanced after the 1-month withdrawal period. We suggest that the former may reflect a persistent elevation in tonic extracellular DA levels in the amygdala, whereas the latter may reflect a persistent elevation in phasic extracellular DA levels.


Asunto(s)
Amígdala del Cerebelo/efectos de los fármacos , Trastornos Relacionados con Cocaína/fisiopatología , Cocaína/toxicidad , Dopamina/metabolismo , Síndrome de Abstinencia a Sustancias/metabolismo , Síndrome de Abstinencia a Sustancias/fisiopatología , Amígdala del Cerebelo/metabolismo , Amígdala del Cerebelo/ultraestructura , Animales , Cocaína/administración & dosificación , Señales (Psicología) , Espacio Extracelular/metabolismo , Masculino , Microdiálisis , Ratas , Ratas Sprague-Dawley , Autoadministración
19.
Mol Biochem Parasitol ; 72(1-2): 193-201, 1995 Jun.
Artículo en Inglés | MEDLINE | ID: mdl-8538689

RESUMEN

A gene, Pf77, transcribed in the sexual stages of Plasmodium falciparum was isolated from a genomic expression library with a polyclonal antibody raised to gametocyte proteins. The entire coding region was obtained from a series of overlapping genomic and cDNA clones (from gametocyte RNA). A single open reading frame is present with no introns and no tandem repeat sequences. A Pf77 probe hybridised to a single transcript present in RNA prepared from purified gametocytes and could not be detected in RNA prepared from asexual blood stages. In situ hybridisation studies confirmed that the expression of Pf77 mRNA is sexual-stage-specific and in addition, showed that Pf77 mRNA is present only in female gametocytes during the vertebrate stages of the parasite's development.


Asunto(s)
Regulación del Desarrollo de la Expresión Génica , Genes Protozoarios , Plasmodium falciparum/genética , Proteínas Protozoarias/biosíntesis , ARN Protozoario/biosíntesis , Secuencia de Aminoácidos , Animales , Anopheles/parasitología , Antígenos de Protozoos/biosíntesis , Antígenos de Protozoos/genética , Antígenos de Protozoos/inmunología , Secuencia de Bases , ADN Protozoario/genética , Femenino , Biblioteca de Genes , Hibridación in Situ , Insectos Vectores/parasitología , Ratones , Datos de Secuencia Molecular , Plasmodium falciparum/crecimiento & desarrollo , Plasmodium falciparum/inmunología , Proteínas Protozoarias/genética , Proteínas Protozoarias/inmunología , ARN Protozoario/genética
20.
Mol Biochem Parasitol ; 104(2): 205-17, 1999 Nov 30.
Artículo en Inglés | MEDLINE | ID: mdl-10593176

RESUMEN

The parasitic protozoan Trypanosoma cruzi undergoes several differentiation events during its life cycle. Some of these transitions are thought to involve activation of adenylyl cyclase via the binding of peptide ligands to the cell surface. Here we describe the characterisation of the adenylyl cyclase gene family of T. cruzi. Two complete genes and one pseudogene have been sequenced. The protein products appear to have a large extracellular domain, a single transmembrane helix and a cytosolic catalytic domain. The adenylyl cyclase genes are present on at least six chromosomes and are scattered rather than clustered. They form a large polymorphic family in which the extracellular domain is particularly variable. An Escherichia coli adenylyl cyclase mutant could be complemented by expression of the catalytic domain of the T. cruzi enzyme. The recombinant protein had adenylyl cyclase activity in vitro, which was enhanced by increasing concentrations of divalent cations (Mn2+ > Mg2+). This constitutively active recombinant protein will be a useful tool for dissecting the catalytic mechanism of adenylyl cyclase.


Asunto(s)
Adenilil Ciclasas/genética , Adenilil Ciclasas/metabolismo , Familia de Multigenes , Trypanosoma cruzi/genética , Adenilil Ciclasas/química , Secuencia de Aminoácidos , Animales , Southern Blotting , Dominio Catalítico , Mapeo Cromosómico , ADN Complementario , Genes Protozoarios , Prueba de Complementación Genética , Datos de Secuencia Molecular , Proteínas Recombinantes/química , Proteínas Recombinantes/metabolismo , Alineación de Secuencia , Análisis de Secuencia de ADN , Trypanosoma cruzi/enzimología , Trypanosoma cruzi/crecimiento & desarrollo
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