RESUMEN
There is increasing evidence for the health benefits of dietary nitrates including lowering blood pressure and enhancing cardiovascular health. Although commensal oral bacteria play an important role in converting dietary nitrate to nitrite, very little is known about the potential role of these bacteria in blood pressure regulation and maintenance of vascular tone. The main purpose of this review is to present the current evidence on the involvement of the oral microbiome in mediating the beneficial effects of dietary nitrate on vascular function and to identify sources of inter-individual differences in bacterial composition. A systematic approach was used to identify the relevant articles published on PubMed and Web of Science in English from January 1950 until September 2019 examining the effects of dietary nitrate on oral microbiome composition and association with blood pressure and vascular tone. To date, only a limited number of studies have been conducted, with nine in human subjects and three in animals focusing mainly on blood pressure. In general, elimination of oral bacteria with use of a chlorhexidine-based antiseptic mouthwash reduced the conversion of nitrate to nitrite and was accompanied in some studies by an increase in blood pressure in normotensive subjects. In conclusion, our findings suggest that oral bacteria may play an important role in mediating the beneficial effects of nitrate-rich foods on blood pressure. Further human intervention studies assessing the potential effects of dietary nitrate on oral bacteria composition and relationship to real-time measures of vascular function are needed, particularly in individuals with hypertension and those at risk of developing CVD.
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Microbiota , Nitratos , Animales , Presión Sanguínea , Humanos , Antisépticos Bucales , Óxido Nítrico , NitritosRESUMEN
PURPOSE: Previously, the nutritional contribution, environmental and financial costs of dairy products have been examined independently. Our aim was to determine the nutritional adequacy, financial cost and environmental impact of UK diets according to dairy content. METHODS: In this cross-sectional study of adults (19-64 years) from the UK National Diet and Nutrition Survey years 1-4 (n = 1655), dietary intakes assessed from 4-day estimated food diaries were organized into quartiles (Q) total grams of dairy (milk, cheese, yogurt, dairy desserts) and analyzed using ANCOVA controlling for age, sex and energy intake with Bonferroni post hoc test for nutritional adequacy, Alternative Healthy Eating Index (AHEI-2010), environmental impact [greenhouse gas emissions (GHGE), eutrophication and acidification potentials], financial cost, markers of health and cardio-metabolic diseases. RESULTS: Nutritional adequacy, particularly for protein, calcium and iodine (+ 18 g, + 533 mg, + 95 g, respectively, all P < 0.0001) and AHEI-2010 (P < 0.0001) were significantly higher and systolic BP (- 2 mmHg, P = 0.019) was significantly lower for the higher-dairy diets (Q4, 274-1429 g/day dairy), compared with diets containing lower dairy (Q1, 0-96 g/day dairy). Diets in Q4 had lower financial cost (- 19%, P < 0.0001) and the greatest eutrophication potential, compared with Q1 (+ 29%, P < 0.0001). Yet the environmental (GHGE) and financial costs per unit nutrient (riboflavin, zinc, iodine, magnesium, calcium, potassium) were lower in Q4 than Q1 (all P < 0.0001). CONCLUSION: Diets with the highest dairy content had higher nutrient composition, better diet quality, were associated with lower BP and financial cost, but with higher eutrophication potential. Robust environmental data for many of food groups are limited and this needs an urgent addressing. TRIAL REGISTRATION: This trial was registered on clinicaltrials.gov as NCT03407248.
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Productos Lácteos/economía , Productos Lácteos/estadística & datos numéricos , Dieta/economía , Dieta/métodos , Ingestión de Energía , Eutrofización , Adulto , Estudios Transversales , Registros de Dieta , Femenino , Humanos , Masculino , Persona de Mediana Edad , Encuestas Nutricionales/métodos , Encuestas Nutricionales/estadística & datos numéricos , Reino Unido , Adulto JovenRESUMEN
PURPOSE: Yogurt consumption has been associated with higher nutrient intakes, better diet quality and improved metabolic profiles in adults. Few studies have investigated these associations in children. This study investigated the association of yogurt consumption with nutrient intakes, diet quality and metabolic profile in British children. METHODS: Data from 1687 children aged 4-10 and 11-18 years of the National Diet and Nutrition Survey (NDNS) years 1-4 were analysed. Yogurt consumption was determined using a 4-day diet diary. Diet quality was assessed by the Healthy Eating Index 2010 (HEI-2010). Anthropometric measures, blood pressure, pulse pressure, plasma glucose, HbA1c, C-reactive protein, triacylglycerol, total cholesterol, high-and low-density cholesterol from NDNS were used. RESULTS: The highest tertile of yogurt consumption (T3) was associated with higher nutrient intakes, particularly for calcium (children 4-10 years: P < 0.0001; children 11-18 years P = 0.001), iodine (both age groups P < 0.0001) and riboflavin (both age groups P < 0.0001), and HEI-2010 score (both age groups P < 0.0001) in children aged 4-10 years (mean ± SD: 98.4 ± 35.7 g yogurt/day) and 11-18 years (mean ± SD: 105.4 ± 37.5 g yogurt/day) compared with non-consumers (0 g yogurt/d). Yogurt consumption was associated with significantly lower pulse pressure in children aged 4-10 years and lower HbA1c concentration, being shorter and having a larger hip circumference in children aged 11-18 years, compared with non-yogurt consumers. CONCLUSION: This study suggests that British children who are yogurt consumers (> 60 g/day) have higher overall diet quality, nutrient intakes and adequacy, lower pulse pressure (children aged 4-10 years) and HbA1c concentrations (children aged 11-18 years), were shorter and had a smaller hip circumference (children aged 11-18 years).
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Dieta/métodos , Ingestión de Energía , Metaboloma , Encuestas Nutricionales/estadística & datos numéricos , Yogur , Adolescente , Glucemia/metabolismo , Proteína C-Reactiva/metabolismo , Niño , Preescolar , Estudios Transversales , Dieta/normas , Registros de Dieta , Femenino , Hemoglobina Glucada/metabolismo , Humanos , Lípidos/sangre , Masculino , Encuestas Nutricionales/métodos , Reino UnidoRESUMEN
Our objective was to investigate whether the presence of Glu298Asp polymorphism in the endothelial NO synthase (eNOS) gene differentially affects the postprandial blood pressure response to dietary nitrate-rich beetroot bread. A randomised, single-blind, controlled, crossover acute pilot study was performed in 14 healthy men (mean age: 34±9 years) who were retrospectively genotyped for Glu298Asp polymorphism (7GG; T carriers 7). Volunteers were randomised to receive 200 g beetroot-enriched bread (1.1 mmol nitrate) or control bread (no beetroot; 0.01 mmol nitrate) on two separate occasions 10 days apart. Baseline and incremental area under the curve of blood pressure and NOx (nitrate/nitrite) were measured for a 6-h postprandial period. A treatment × genotype interaction was observed for diastolic blood pressure (P<0.02), which was significantly lower in T carriers (P<0.01) after consumption of beetroot bread compared with control bread. No significant differences were observed in the GG group. The beneficial diastolic blood pressure reduction was observed only in the T carriers of the Glu298Asp polymorphism in the eNOS gene after consumption of nitrate-rich beetroot bread. These data require confirmation in a larger population group.
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Presión Sanguínea , Óxido Nítrico Sintasa de Tipo III/genética , Polimorfismo de Nucleótido Simple , Verduras/química , Adolescente , Adulto , Pan , Humanos , Masculino , Persona de Mediana Edad , Nitratos/análisis , Proyectos PilotoRESUMEN
Sarcoidosis is a multisystem disease of unknown etiology primarily affecting the lungs, skin, and lymph nodes. The disease usually manifests in young adults and is uncommon in childhood. Renal involvement, including granulomatous interstitial nephritis (GIN), is rare, and few cases of isolated sarcoid GIN have been reported in pediatrics. We report a case and review the literature.
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Granuloma/diagnóstico , Nefritis Intersticial/diagnóstico , Sarcoidosis/diagnóstico , Adolescente , Humanos , Hipertensión Renal/etiología , Masculino , Nefritis Intersticial/complicaciones , Sarcoidosis/complicacionesRESUMEN
Excavations at Liang Bua, Flores, Indonesia, have yielded evidence for an endemic human species, Homo floresiensis, a population that occupied the cave between approximately 95-17ka. This discovery has major implications for early hominin evolution and dispersal in Africa and Asia, attracting worldwide interest. This preface describes the rationale for the excavations in historical, geographical, and wider research contexts, as well as the methods used. It also introduces the other papers on aspects of Liang Bua research that feature in this edition of the Journal of Human Evolution.
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Evolución Biológica , Fósiles , Fenómenos Geológicos , Animales , Arqueología , Historia Antigua , Hominidae/anatomía & histología , Hominidae/clasificación , Hominidae/genética , Humanos , Indonesia , InvestigaciónRESUMEN
Liang Bua, in Flores, Indonesia, was formed as a subterranean chamber over 600ka. From this time to the present, a series of geomorphic events influenced the structure of the cave and cave deposits, creating a complex stratigraphy. Within these deposits, nine main sedimentary units have been identified. The stratigraphic relationships between these units provide the evidence needed to reconstruct the geomorphic history of the cave. This history was dominated by water action, including slope wash processes, channel formation, pooling of water, and flowstone precipitation, which created waterfalls, cut-and-fill stratigraphy, large pools of water, and extensive flowstone cappings. The reconstructed sequence of events over the last 190k.yr. has been summarized by a series of time slices that demonstrate the nature of the occupational environment in Liang Bua. The earliest artifacts at the site, dated to approximately 190ka, testify to hominin presence in the area, but the reconstructions suggest that occupation of the cave itself may not have been possible until after approximately 100ka. At approximately 95ka, channel erosion of a basal unit, which displays evidence of deposition in a pond environment, created a greater relief on the cave floor, and formed remanent areas of higher ground that later became a focus for hominin occupation from 74-61ka by the west wall and in the center of the cave, and from approximately 18-17ka by the east wall. These zones have been identified according to the sloping nature of the stratigraphy and the distribution of artifacts, and their locations have implications for the archaeological interpretation of the site.
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Fenómenos Geológicos , Animales , Arqueología , Evolución Biológica , Geografía , Hominidae/clasificación , Hominidae/genética , Humanos , IndonesiaRESUMEN
Guided by structure-based design, we synthesized two novel series of potent inhibitors of BACE1 and generated extensive SAR around both the prime and non-prime side binding pockets. The key feature of both series is a cyclic amine motif specifically crafted to achieve interactions with both the flap and with the S2' pocket.
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Secretasas de la Proteína Precursora del Amiloide/antagonistas & inhibidores , Ácido Aspártico Endopeptidasas/antagonistas & inhibidores , Diseño de Fármacos , Imidazolidinas/síntesis química , Imidazolidinas/farmacología , Piperazinas/síntesis química , Piperazinas/farmacología , Animales , Cristalografía por Rayos X , Modelos Animales de Enfermedad , Humanos , Imidazolidinas/química , Ratones , Ratones Transgénicos , Modelos Moleculares , Conformación Molecular , Estructura Molecular , Piperazinas/química , Relación Estructura-ActividadRESUMEN
UNLABELLED: Monosodium titanate (MST) particles effectively bind specific metals and are therefore promising compounds for delivery or sequestration of metals in biological contexts. Yet, the biological properties of MST are largely unexplored. Our previous study showed that the cytotoxicity of these compounds was mild, but the nature of the dose response curves suggested that residual titanates in culture may have interfered with the assay. In the current study, we assessed the importance of these artifacts, and extended our previous results using fibroblasts for biological evaluation. We also assessed the biological response to a new type of titanate (referred to as amorphous peroxo-titanate or APT) that shows more promising metal binding properties than MST. METHODS: The degree of titanate-induced interference in the MTT (mitochondrial activity assay) was estimated by means of cell-free assays with and without a final centrifugation step to remove residual titanate particulate. Cytotoxic responses to titanates were assessed by measuring succinate dehydrogenase activity (by MTT) in THP1 monocytes or L929 fibroblasts after 24-72 h exposures. Monocytic activation by APT was assessed by TNFalpha secretion (ELISA) from monocytes with or without lipopolysaccharide (LPS) activation. RESULTS: We confirmed that residual titanate particulates may alter the SDH activity assay, but that this effect is eliminated by adding a final centrifugation step to the standard MTT procedure. Addition of MST or APT at concentrations up to 100 mg/L altered succinate dehydrogenase activity by < 25% in both monocytes and fibroblasts. Fibroblasts displayed time-dependent adaptation to the MST. APT did not trigger TNFalpha secretion or modulate LPS-induced TNFalpha secretion from monocytes. CONCLUSIONS: Although further in vitro and in vivo assessment is needed, MST and APT exhibit biological properties that are promising for their use as agents to sequester or deliver metals in biological systems.
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Materiales Biocompatibles/toxicidad , Fibroblastos/efectos de los fármacos , Monocitos/efectos de los fármacos , Óxidos/toxicidad , Titanio/toxicidad , Animales , Materiales Biocompatibles/química , Línea Celular , Fibroblastos/enzimología , Humanos , Ensayo de Materiales , Ratones , Mitocondrias/efectos de los fármacos , Monocitos/inmunología , Óxidos/química , Succinato Deshidrogenasa/análisis , Titanio/química , Factor de Necrosis Tumoral alfa/análisisRESUMEN
Monosodium titanate (MST) is an inorganic sorbent/ion exchanger developed for the removal of radionuclides from nuclear wastes. We investigated the ability of MST to bind Cd(II), Hg(II), Au(III), or the Au-organic compound auranofin to establish the utility of MST for applications in environmental decontamination or medical therapy (drug delivery). Adsorption isotherms for MST were determined at pH 7-7.5 in water or phosphate-buffered saline. The extent of metal binding was determined spectroscopically by measuring the concentrations of the metals in solution before and after contact with the MST. Cytotoxic responses to MST were assessed using THP1 monocytes and succinate dehydrogenase activity. Monocytic activation by MST was assessed by TNFalpha secretion (ELISA) with or without lipopolysaccharide (LPS) activation. MST adsorbed Cd(II), Hg(II), and Au(III) under conditions similar to those in physiological systems. MST exhibited the highest affinity for Cd(II) followed by Hg(II) and Au (III). MST (up to 100 mg/L) exhibited only minor (<25% suppression of succinate dehydrogenase) cytotoxicity and did not trigger TNFalpha secretion nor modulate LPS-induced TNFalpha secretion from monocytes. MST exhibits high affinity for biometals with no significant biological liabilities in these introductory studies. MST deserves further scrutiny as a substance with the capacity to decontaminate biological environments or deliver metals or metal compounds for therapeutic applications.
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Auranofina/química , Sistemas de Liberación de Medicamentos , Metales Pesados/química , Monocitos , Adsorción , Auranofina/uso terapéutico , Materiales Biocompatibles , Línea Celular , Descontaminación , Humanos , Intercambio Iónico , Lipopolisacáridos/farmacología , Lipopolisacáridos/toxicidad , Ensayo de Materiales , Metales Pesados/uso terapéutico , Monocitos/metabolismo , Monocitos/ultraestructura , Residuos Radiactivos , Succinato Deshidrogenasa/metabolismo , Factor de Necrosis Tumoral alfa/metabolismoRESUMEN
Excavations at Liang Bua, a large limestone cave on the island of Flores in eastern Indonesia, have yielded evidence for a population of tiny hominins, sufficiently distinct anatomically to be assigned to a new species, Homo floresiensis. The finds comprise the cranial and some post-cranial remains of one individual, as well as a premolar from another individual in older deposits. Here we describe their context, implications and the remaining archaeological uncertainties. Dating by radiocarbon (14C), luminescence, uranium-series and electron spin resonance (ESR) methods indicates that H. floresiensis existed from before 38,000 years ago (kyr) until at least 18 kyr. Associated deposits contain stone artefacts and animal remains, including Komodo dragon and an endemic, dwarfed species of Stegodon. H. floresiensis originated from an early dispersal of Homo erectus (including specimens referred to as Homo ergaster and Homo georgicus) that reached Flores, and then survived on this island refuge until relatively recently. It overlapped significantly in time with Homo sapiens in the region, but we do not know if or how the two species interacted.
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Arqueología , Biodiversidad , Hominidae , Animales , Evolución Biológica , Constitución Corporal , Radioisótopos de Carbono , Femenino , Geografía , Historia Antigua , Hominidae/clasificación , Actividades Humanas/historia , Humanos , Indonesia , Conducta Predatoria , Reproducibilidad de los Resultados , Esqueleto , Cráneo , Factores de Tiempo , DienteRESUMEN
High-level waste (HLW) is a waste associated with the dissolution of spent nuclear fuel for the recovery of weapons-grade material. It is the priority problem for the U.S. Department of Energy's Environmental Management Program. Current HLW treatment processes at the Savannah River Site (Aiken, SC) include the use of monosodium titanate (MST, with a similar stoichiometry to NaTi2O5 x xH2O) to concentrate strontium (Sr) and actinides. The high affinity of MST for Sr and actinides in HLW solutions rich in Na+ is poorly understood. Mechanistic information about the nature of radionuclide uptake will provide insight about MST treatment reliability. Our study characterized the morphology of MST and the chemistry of sorbed Sr2+ and uranium [U(VI)] as uranyl ion, UO2(2+), on MST, which were added (individually) from stock solutions of Sr and 238U(VI) with spectroscopic and transmission electron microscopic techniques. The local structure of sorbed U varied with loading, but the local structure of Sr did not vary with loading. Sorbed Sr exhibited specific adsorption as partially hydrated species whereas sorbed U exhibited specific adsorption as monomeric and dimeric U(VI)-carbonate complexes. Sorption proved site specific. These differences in site specificity and sorption mechanism may account forthe difficulties associated with predicting Sr and U loading and removal kinetics using MST.
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Residuos Radiactivos , Estroncio/aislamiento & purificación , Titanio/química , Uranio/aislamiento & purificación , Adsorción , Microscopía Electrónica de Transmisión , Análisis EspectralRESUMEN
In recent years the trend in combinatorial library design has shifted to include target class focusing along with diversity and drug-likeness criteria. In this manuscript we review the computational tools available for target class library design and highlight the areas where they have proven useful in our work. The protein kinase family is used to illustrated structure-based target class focused library design, and the G-protein coupled receptor (GPCR) family is used to illustrate ligand-based target class focused library design. Most of the tools discussed are those designed for libraries targeted to a single protein and are simply applied "brute-force" to a large number of targets within the family. The tools that have proven to be the most useful in our work are those that can extract trends from the computational data such as docking and clustering or data mining large amounts of structure activity or high throughput screening data. Finally, areas where improvements are needed in the computational tools available for target class focusing are highlighted. These areas include tools to extract the relevant patterns from all available information for a family of targets, tools to efficiently apply models for all targets in the family rather than just a small subset, mining tools to extract the relevant information from the computational absorption, distribution, metabolism, excretion and toxicity (ADMET) and targeting data, and tools to allow interactive exploration of the virtual space around a library to facilitate the selection of the library that best suits the needs of the design team.
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Diseño de Fármacos , Fosfotransferasas/antagonistas & inhibidores , Receptores Acoplados a Proteínas G/antagonistas & inhibidores , Animales , Biblioteca Genómica , Humanos , Ligandos , Modelos Moleculares , Conformación Molecular , Fosfotransferasas/química , Fosfotransferasas/genética , Inhibidores de Proteínas Quinasas , Proteínas Quinasas/química , Receptores Acoplados a Proteínas G/química , Receptores Acoplados a Proteínas G/genética , Relación Estructura-ActividadAsunto(s)
Técnicas Químicas Combinatorias , Diseño de Fármacos , Evaluación Preclínica de Medicamentos , Estructura Molecular , Compuestos Orgánicos/síntesis química , Compuestos Orgánicos/química , Receptores de Superficie Celular/efectos de los fármacos , Receptores de Droga/efectos de los fármacosRESUMEN
We developed a statistical model that would identify and quantify the relative contributions of different factors hypothesized to impact the frequency of emergency center (EC) patients who leave without being seen (LWBS). We performed an analysis of the daily counts of patients that registered in our EC during a 21-month period who then LWBS. Candidate predictor variables included the number of patients seen, and the number admitted to the hospital, for each area of our EC, as well as the hours of faculty double coverage, and the day of the week. Univariate analyses were performed using standard methods. Multivariate analysis was performed using the general linear model. A backward selection procedure was used to eliminate statistically insignificant variables until all remaining independent variables had P-values < or = .05. External validation and analysis of the stability of the estimated regression coefficients of the model were evaluated using bootstrap methods. Two-tailed tests and a type I error of 0.05 were used. During the period studied, 133,666 patients were registered in the EC and 9,894 (7.4%) left. Multivariate analysis identified six variables that were significantly associated with LWBS. The fitted model containing all six variables explained 52.8% of the variability observed in LWBS frequency. The most powerful predictor of LWBS was total number of patients cared for in the main ED. This accounted for 46.4% of the observed variation in LWBS. The total number of trauma and resuscitation patients, and the total number of observation unit admissions to the hospital were also associated with increased LWBS. More pediatric cases seen in the main ED, weekends, and additional faculty coverage were associated with fewer patients leaving. Efforts to decrease the LWBS rate will be most successful if they address the issue of main ED volume.
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Servicio de Urgencia en Hospital , Admisión del Paciente , Listas de Espera , Adolescente , Adulto , Niño , Femenino , Accesibilidad a los Servicios de Salud , Humanos , Masculino , Estudios Retrospectivos , Factores de TiempoRESUMEN
Earlier studies have demonstrated evidence for increased reactive oxygen species, enhanced NO synthase (NOS) expression, and elevated NO production in spontaneously hypertensive rats (SHR). Given the negative-feedback regulation of NOS by NO, we hypothesized that enhanced NO inactivation by ROS may contribute to compensatory upregulation of NOS in SHR. The present study was designed to test this hypothesis. Eight-week-old male SHR and Wistar-Kyoto rats were treated for 3 weeks with either a placebo or the potent antioxidant, lazaroid (desmethyltirilazad, 10 mg. kg(-1). d(-1), by gastric gavage). Tail arterial blood pressure, urinary excretion of NO metabolites (ie, nitrate and nitrite), and immunodetectable NOS isotype proteins in the vascular, renal, cardiac, and cerebral tissues were measured. The placebo-treated SHR group showed a marked elevation of blood pressure and a significant upregulation of aorta, kidney, and cardiac tissue endothelial and inducible NOS (eNOS and iNOS, respectively) proteins and of brain and renal tissue neuronal NOS. Lazaroid therapy ameliorated hypertension and mitigated the upregulation of eNOS and iNOS in vascular, renal, and cardiac tissues but had limited effect on the expression of renal and brain neuronal NOS. In contrast, lazaroid therapy had no effect on blood pressure, urinary nitrate and nitrite excretion, or tissue NOS isotype expressions in the Wistar-Kyoto group. These findings support the role of oxidative stress in the genesis and/or maintenance of hypertension and compensatory upregulation of the expression of eNOS and iNOS in SHR.
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Antioxidantes/uso terapéutico , Hipertensión/tratamiento farmacológico , Óxido Nítrico Sintasa/biosíntesis , Animales , Aorta/efectos de los fármacos , Aorta/enzimología , Presión Sanguínea/efectos de los fármacos , Encéfalo/efectos de los fármacos , Encéfalo/enzimología , Modelos Animales de Enfermedad , Radicales Libres/metabolismo , Corazón/efectos de los fármacos , Hipertensión/enzimología , Hipertensión/fisiopatología , Isoenzimas/biosíntesis , Riñón/efectos de los fármacos , Riñón/enzimología , Masculino , Óxido Nítrico/metabolismo , Ratas , Ratas Endogámicas SHR , Ratas Endogámicas WKYRESUMEN
This paper focuses upon the emergence of the night-time economy both materially and culturally as a powerful manifestation of post-industrial society. This emergence features two key processes: firstly a shift in economic development from the industrial to the post-industrial; secondly a significant orientation of urban governance involving a move away from the traditional managerial functions of local service provision, towards an entrepreneurial stance primarily focused on the facilitation of economic growth. Central to this new economic era is the identification and promotion of liminality. The State's apparent inability to control these new leisure zones constitutes the creation of an urban frontier that is governed by commercial imperatives.
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Comercio/organización & administración , Toma de Decisiones en la Organización , Economía/tendencias , Empleo/organización & administración , Gobierno Local , Admisión y Programación de Personal/organización & administración , Política , Sector Privado/organización & administración , Población Urbana , Emprendimiento , Humanos , Relaciones Interinstitucionales , Innovación Organizacional , Medidas de Seguridad/organización & administración , Cambio Social , Sociología , Factores de TiempoRESUMEN
Diacylglycerol acyltransferase (DGAT) catalyses the acylation of the sn-3 hydroxy group of sn-1,2-diacylglycerol using acyl-CoA. The gene encoding DGAT from Arabidopsis thaliana has been cloned and the function of the enzyme proved by expression of the coding sequence using a bacculovirus expression system in insect cell cultures. The expressed protein catalysed the synthesis of [(14)C]triacylglycerol from [(14)C]diacylglycerol and oleoyl-CoA. The heterologously expressed DGAT activity was found mostly associated with the 100000 g pellet. The optimum activity was achieved at a neutral pH, in the presence of Mg2+, and at an optimum oleoyl-CoA concentration of 20 microM. The DGAT used the substrates palmitoyl-CoA and oleoyl-CoA equally effectively. In these experiments, the inclusion of recombinant acyl-CoA binding protein had a relatively small effect upon DGAT activity.
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Aciltransferasas/metabolismo , Arabidopsis/enzimología , Microsomas/enzimología , Acilcoenzima A/metabolismo , Aciltransferasas/genética , Animales , Arabidopsis/genética , Baculoviridae , Línea Celular , Diacilglicerol O-Acetiltransferasa , Diglicéridos/metabolismo , Insectos , Cinética , Proteínas Recombinantes/metabolismo , TransfecciónRESUMEN
Triacylglycerols are the most important storage lipids in most plants and animals. Acyl-CoA:diacylglycerol acyltransferase (EC 2.3.1.20) catalyzes the final step of the pathway of triacylglycerol synthesis and is the only step which is unique to this process. Diacylglycerol acyltransferase is required for the synthesis of storage oil in a wide range of oil-bearing seeds and fruits and in floral structures such as petals, anthers and pollen. We describe the first cloning and functional expression of a cDNA encoding diacylglycerol acyltransferase from a plant. The cDNA, cloned from Arabidopsis thaliana, encodes a 520 amino acid protein with a predicted molecular mass of 59.0 kDa which shares 38% amino acid sequence identity with diacylglycerol acyltransferase from mouse. When expressed in insect cell cultures, the protein catalyzes the synthesis of [14C]triacylglycerol from [14C]diacylglycerol and acyl-CoA. Primer extension analysis revealed that the transcription begins 225 bases before the translation start site, yielding an unusually long 5' untranslated region. The gene is expressed in a wide range of tissues but most strongly in developing embryos and petals of flowers.
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Aciltransferasas/genética , Aciltransferasas/metabolismo , Arabidopsis/enzimología , Aciltransferasas/química , Secuencia de Aminoácidos , Animales , Arabidopsis/genética , Secuencia de Bases , Clonación Molecular , ADN Complementario , Bases de Datos como Asunto , Diacilglicerol O-Acetiltransferasa , Ratones , Datos de Secuencia Molecular , Peso Molecular , Proteínas Recombinantes/biosíntesis , Proteínas Recombinantes/química , Proteínas Recombinantes/metabolismo , Alineación de Secuencia , Homología de Secuencia de Aminoácido , Transcripción GenéticaRESUMEN
The design of integrating cavity absorption meters of general geometry is analyzed for cases in which the incident illumination of the cavity is spatially uniform and isotropic, such as the meter of Fry et al. [Appl. Opt. 31, 2055 (1992)]. The analysis by Kirk [Appl. Opt. 34, 4397 (1995)] for the probability of photon survival in a spherical meter is extended to general geometries. An estimate of the effect of the shape of the cavity on the estimated absorption coefficient is given.