Your browser doesn't support javascript.
Mostrar: 20 | 50 | 100
Resultados 1 - 13 de 13
Filtrar
Más filtros










Base de datos
Intervalo de año de publicación
1.
J Nurs Educ ; 58(2): 110-113, 2019 Feb 01.
Artículo en Inglés | MEDLINE | ID: mdl-30721312

RESUMEN

BACKGROUND: Contemporary teaching and learning pedagogy commands interprofessional collaboration among allied professions such as nursing and social work, two professions that have a natural inclination to partner in the workforce. METHOD: Nursing and social work students participated in a structured simulated learning experience where they demonstrated their respective professional practice skills in a supported learning environment while working collaboratively to assess one of two patient types: high-fidelity or simulated. RESULTS: Both groups expressed initial worry during prebriefing but articulated their appreciation for and usefulness of working with the other profession. Future collaboration includes learning about respective professional roles, more direction regarding the professional handoff, and prior exposure to the appearance and functionality of high-fidelity patient types in an effort to establish best strategies for partnership. CONCLUSION: Interprofessional collaboration diverges from the silo effect, leading to collegiality among affiliated professionals, as well as increased patient safety and improved patient outcomes. [J Nurs Educ. 2019;58(2):110-113.].


Asunto(s)
Prácticas Interdisciplinarias/métodos , Relaciones Interprofesionales , Enfermeras Practicantes/educación , Aprendizaje Basado en Problemas/métodos , Entrenamiento Simulado/organización & administración , Conducta Cooperativa , Humanos , Investigación en Educación de Enfermería , Estudiantes de Enfermería
2.
Psychooncology ; 26(2): 182-190, 2017 02.
Artículo en Inglés | MEDLINE | ID: mdl-26494568

RESUMEN

OBJECTIVE: This research examines the relative importance that cancer-related and non-cancer illness factors play in generating general health worries and/or cancer-related worries. The analysis also examines how these in turn impact anxiety and depression among older adult, long-term cancer survivors. METHODS: Data from a longitudinal study of 245 older-adult (age 60+ years), long-term survivors (5 or more years after diagnosis) of breast, prostate, and colorectal cancer are examined to identify the measurement properties and structure of general health and cancer-related health worries. Based on that measurement analysis, structural equation models (SEM) are used to estimate the relative importance of cancer-related and other illness predictors on cancer-related worry and general health worry and how these two forms of worry affect both anxiety (POMS) and depression (CES-D). RESULTS: The results from the exploratory and confirmatory factor analysis of health worries identify two relatively independent measures of health worry, one of general health worry and a second of cancer-related worries that includes fears of recurrence, new cancers, and follow-up testing. SEM analyses identified the importance of current cancer-related symptoms and comorbidities on cancer-related worry. It also documents the primacy of non-cancer symptoms and general health worry as predictors of anxiety and depression among older survivors. CONCLUSIONS: The fact that cancer-related symptoms continue to be associated with cancer-related worries years after diagnosis speaks to the significance of these continuing sequelae. While the findings suggest the relative independence of cancer-related worries and general health worries, both are correlated with anxiety and depression. This may be particularly problematic as survivors age and symptoms related to new health problems increase, while cancer-related symptoms persist. Copyright © 2015 John Wiley & Sons, Ltd.


Asunto(s)
Neoplasias de la Mama/psicología , Supervivientes de Cáncer/psicología , Depresión/psicología , Conductas Relacionadas con la Salud , Neoplasias de la Próstata/psicología , Anciano , Ansiedad/diagnóstico , Neoplasias Colorrectales/psicología , Análisis Factorial , Miedo , Femenino , Humanos , Estudios Longitudinales , Masculino , Recurrencia Local de Neoplasia/psicología
3.
Int J Environ Res Public Health ; 12(4): 3439-52, 2015 Mar 24.
Artículo en Inglés | MEDLINE | ID: mdl-25811768

RESUMEN

BACKGROUND: Some electronic cigarette (EC) liquids of tobacco flavour contain extracts of cured tobacco leaves produced by a process of solvent extraction and steeping. These are commonly called Natural Extract of Tobacco (NET) liquids. The purpose of the study was to evaluate nicotine levels and the presence of tobacco-derived toxins in tobacco-flavoured conventional and NET liquids. METHODS: Twenty-one samples (10 conventional and 11 NET liquids) were obtained from the US and Greek market. Nicotine levels were measured and compared with labelled values. The levels of tobacco-derived chemicals were compared with literature data on tobacco products. RESULTS: Twelve samples had nicotine levels within 10% of the labelled value. Inconsistency ranged from -21% to 22.1%, with no difference observed between conventional and NET liquids. Tobacco-specific nitrosamines (TSNAs) were present in all samples at ng/mL levels. Nitrates were present almost exclusively in NET liquids. Acetaldehyde was present predominantly in conventional liquids while formaldehyde was detected in almost all EC liquids at trace levels. Phenols were present in trace amounts, mostly in NET liquids. Total TSNAs and nitrate, which are derived from the tobacco plant, were present at levels 200-300 times lower in 1 mL of NET liquids compared to 1 gram of tobacco products. CONCLUSIONS: NET liquids contained higher levels of phenols and nitrates, but lower levels of acetaldehyde compared to conventional EC liquids. The lower levels of tobacco-derived toxins found in NET liquids compared to tobacco products indicate that the extraction process used to make these products did not transfer a significant amount of toxins to the NET. Overall, all EC liquids contained far lower (by 2-3 orders of magnitude) levels of the tobacco-derived toxins compared to tobacco products.


Asunto(s)
Sistemas Electrónicos de Liberación de Nicotina , Nicotina/análisis , Extractos Vegetales/análisis , Tabaco/química , Acetaldehído/análisis , Formaldehído/análisis , Nitratos/análisis , Nitrosaminas/análisis , Fenoles/análisis , Tabaco/toxicidad
4.
PLoS Pathog ; 9(11): e1003786, 2013.
Artículo en Inglés | MEDLINE | ID: mdl-24278024

RESUMEN

Little is known about how the mode of respiratory virus transmission determines the dynamics of primary infection and protection from reinfection. Using non-invasive imaging of murine parainfluenza virus 1 (Sendai virus) in living mice, we determined the frequency, timing, dynamics, and virulence of primary infection after contact and airborne transmission, as well as the tropism and magnitude of reinfection after subsequent challenge. Contact transmission of Sendai virus was 100% efficient, phenotypically uniform, initiated and grew to robust levels in the upper respiratory tract (URT), later spread to the lungs, grew to a lower level in the lungs than the URT, and protected from reinfection completely in the URT yet only partially in the lungs. Airborne transmission through 7.6-cm and 15.2-cm separations between donor and recipient mice was 86%-100% efficient. The dynamics of primary infection after airborne transmission varied between individual mice and included the following categories: (a) non-productive transmission, (b) tracheal dominant, (c) tracheal initiated yet respiratory disseminated, and (d) nasopharyngeal initiated yet respiratory disseminated. Any previous exposure to Sendai virus infection protected from mortality and severe morbidity after lethal challenge. Furthermore, a higher level of primary infection in a given respiratory tissue (nasopharynx, trachea, or lungs) was inversely correlated with the level of reinfection in that same tissue. Overall, the mode of transmission determined the dynamics and tropism of primary infection, which in turn governed the level of seroconversion and protection from reinfection. These data are the first description of the dynamics of respiratory virus infection and protection from reinfection throughout the respiratory tracts of living animals after airborne transmission. This work provides a basis for understanding parainfluenza virus transmission and protective immunity and for developing novel vaccines and non-pharmaceutical interventions.


Asunto(s)
Sistema Respiratorio , Infecciones por Respirovirus , Virus Sendai , Tropismo Viral/inmunología , Animales , Masculino , Ratones , Sistema Respiratorio/inmunología , Sistema Respiratorio/patología , Sistema Respiratorio/virología , Infecciones por Respirovirus/inmunología , Infecciones por Respirovirus/patología , Infecciones por Respirovirus/prevención & control , Infecciones por Respirovirus/transmisión , Virus Sendai/inmunología , Virus Sendai/metabolismo , Virus Sendai/patogenicidad
5.
Xenobiotica ; 43(2): 169-81, 2013 Feb.
Artículo en Inglés | MEDLINE | ID: mdl-22830980

RESUMEN

n-Butyl-p-hydroxybenzoate (n-butylparaben, BPB) is an antioxidant used in foods, pharmaceuticals and cosmetics. This study investigated the disposition of ring-labelled [(14)C]BPB in Harlan Sprague Dawley rats, and in rat and human hepatocytes. BPB was rapidly cleared in hepatocytes from rat (t(1/2) = 3-4 min) and human (t(1/2) = 20-30 min). The major metabolites detected in rat hepatocytes were hydroxybenzoic acid and in human hepatocytes were hydroxybenzoic acid and hydroxyhippuric acid. [(14)C]BPB was administered to male rats orally at 10, 100 or 1000 mg/kg, intravenously at 10 mg/kg and dermally at 10 and 100 mg/kg; female rats were administered oral doses at 10 mg/kg. Oral doses of BPB were well-absorbed (>83%) and eliminated chiefly in urine (83-84%); ≤ 1% of the radioactivity remained in tissues at 24 h or 72 h after dosing. About 4% and 8%, respectively, of 100 mg/kg dermal doses were absorbed in 24 h and 72 h, and about 50% of a 10 mg/kg dose was absorbed in 72 h. Metabolites detected in urine included those previously reported, BPB-glucuronide, BPB-sulfate, hydroxybenzoic acid and hydroxyhippuric acid, but also novel metabolites arising from ring hydroxylation followed by glucuronidation and sulfation.


Asunto(s)
Hepatocitos/metabolismo , Parabenos/metabolismo , Xenobióticos/metabolismo , Administración Cutánea , Administración Oral , Animales , Radioisótopos de Carbono/orina , Femenino , Humanos , Inyecciones Intravenosas , Masculino , Parabenos/administración & dosificación , Ratas , Ratas Sprague-Dawley , Xenobióticos/administración & dosificación
6.
J Anal Toxicol ; 35(6): 341-8, 2011 Jul.
Artículo en Inglés | MEDLINE | ID: mdl-21740690

RESUMEN

A rapid and simple liquid chromatography tandem mass spectrometry method was developed and validated for the simultaneous determination of L-ephedrine, pseudoephedrine, and caffeine in male Fisher-344 rat plasma at nanogram-per-milliliter concentrations for use in support of toxicology studies. Only 25 µL of plasma is required, and extraction is performed using a simple, single-step protein precipitation. The method was validated over a range of 2.09 to 5460 ng/mL for L-ephedrine, 2.09 to 5050 ng/mL for pseudoephedrine and 2.03 to 5340 ng/mL for caffeine. A binary gradient elution at 0.3 mL/min was used with a Waters XBridge Phenyl (2.1 × 150 mm, 3.5 µm) column and a Waters XBridge Phenyl 2.1- × 10-mm guard column at ambient temperature. The mobile phase consisted of 10 mM ammonium acetate in water (pH 5.0) and methanol. Caffeine trimethyl-(13)C(3) was used as the internal standard. The method was evaluated for linearity, recovery, precision, accuracy, and stability, and it was successfully applied in toxicokinetic studies of ephedrine, administered alone, in combination with caffeine, and in the herbal source Ma Huang.


Asunto(s)
Cafeína/sangre , Efedrina/sangre , Seudoefedrina/sangre , Detección de Abuso de Sustancias/métodos , Animales , Cromatografía Liquida , Masculino , Ratas , Espectrometría de Masas en Tándem
7.
J Appl Toxicol ; 30(7): 694-8, 2010 Oct.
Artículo en Inglés | MEDLINE | ID: mdl-20981862

RESUMEN

The intact female weanling version in the Organization for Economic Cooperation and Development (OECD) uterotrophic assay Test Guideline (TG) 440 is proposed as an alternative to the adult ovariectomized female version, because it does not involve surgical intervention (vs the ovariectomized version) and detects direct/indirect-acting estrogenic/anti-estrogenic substances (vs the ovariectomized version which detects only direct-acting estrogenic/anti-estrogenic substances binding to the estrogen receptor). This validation study followed OECD TG 440, with six female weanling rats (postnatal day 21) per dose group and six treatment groups. Females were weighed and dosed once daily by oral gavage for three consecutive days, with one of six doses of 17α-ethinyl estradiol in corn oil at 5 ml kg⁻¹ at 0 and 0.1-10 µg kg⁻¹ per day. On postnatal day 24, the juvenile females were euthanized by CO2 asphyxiation, weighed, livers weighed and uteri weighed wet and blotted. The presence or absence of vaginal patency was recorded. Absolute and relative (to terminal body weight) uterine wet and blotted weights and uterine luminal fluid weights were significantly increased at 3.0 and 10.0 (both P < 0.01) µg kg⁻¹ per day, and increased to ~140% of control values at 1.0 µg kg⁻¹ per day (not statistically significantly). In vivo body weights, weight changes, feed consumption, liver weights and terminal body weights were unaffected. Vaginal patency was not acquired in any female at any dose, although vaginal puckering was observed in one female at 10.0 µg kg⁻¹ per day. Therefore, this intact weanling uterotrophic assay is validated in our laboratory for use under US and European endocrine toxicity testing programs/legislation.


Asunto(s)
Aceite de Maíz/normas , Estrógenos/farmacología , Etinilestradiol/farmacología , Útero/efectos de los fármacos , Animales , Bioensayo , Relación Dosis-Respuesta a Droga , Esquema de Medicación , Sistema Endocrino/efectos de los fármacos , Estrógenos/administración & dosificación , Etinilestradiol/administración & dosificación , Femenino , Intubación Gastrointestinal , Hígado/metabolismo , Tamaño de los Órganos/efectos de los fármacos , Ratas , Ratas Sprague-Dawley , Receptores Estrogénicos/metabolismo , Pruebas de Toxicidad/métodos , Vagina/crecimiento & desarrollo
8.
J Anal Toxicol ; 32(3): 248-52, 2008 Apr.
Artículo en Inglés | MEDLINE | ID: mdl-18397577

RESUMEN

A liquid chromatographic-mass spectrometricmethod for the determination of lovastatin hydroxy acid in female B6C3F(1) mouse serum was developed for use in supporting toxicokinetic studies of animals dosed with the cholesterol lowering agent lovastatin. The method does not require an extensive sample cleanup and shows good correlation between serum matrix standards and solvent standards. The method was validated and used to analyze serum samples from a preliminary dose level range-finding study. The method was validated for a concentration range of approximatel 1.0 to 100 ng/mL in serum, and linearity was verified to ~2000 ng/mL. The stability of sample extracts was determined under various storage conditions and the stability of serum samples stored frozen was determined over a period of seven weeks. During the course of analyzing the animal samples, the serum was monitored for the presence of lovastatin not hydrolyzed to the hydroxy acid, but no attempt was made to quantify lovastatin. No unhydrolyzed lovastatin was noted in any of the serum samples from animals dosed with lovastatin.


Asunto(s)
Anticolesterolemiantes/farmacocinética , Hidroxiácidos/sangre , Lovastatina/farmacocinética , Espectrometría de Masas en Tándem/métodos , Animales , Cromatografía Liquida , Femenino , Ratones , Ratones Endogámicos
9.
Am J Clin Nutr ; 83(5): 1097-105, 2006 May.
Artículo en Inglés | MEDLINE | ID: mdl-16685052

RESUMEN

BACKGROUND: Grapefruit juice (GFJ) enhances the systemic exposure of numerous CYP3A4 drug substrates, including felodipine, by inhibiting intestinal (but not hepatic) first-pass metabolism. Furanocoumarins have been identified as major CYP3A4 inhibitors contained in the juice, but their contribution to the GFJ effect in vivo remains unclear. OBJECTIVE: To ascertain whether furanocoumarins mediate the GFJ-felodipine interaction, a furanocoumarin-free GFJ was created and tested against orange juice and the original GFJ with respect to the oral pharmacokinetics of felodipine. DESIGN: With the use of food-grade solvents and absorption resins, furanocoumarins were removed (approximately 99%) from whole GFJ, whereas other major ingredients (flavonoids) were retained. In an open, 3-way, randomized crossover design, 18 healthy volunteers ingested felodipine (10 mg) with 1 of the 3 juices (240 mL). Blood was collected over 24 h. At least 1 wk elapsed between juice treatments. RESULTS: The median and range of the area under the curve and the maximum concentration of felodipine were significantly (P < 0.001) greater with consumption of GFJ [110 (range: 58-270) nmol . h/L and 21 (7.6-50) nmol/L, respectively] than with that of orange juice [54 (29-150) nmol . h/L and 7.6 (3.4-13.9) nmol/L, respectively] or furanocoumarin-free GFJ [48 (23-120) nmol . h/L and 8.3 (3.0-16.6) nmol/L, respectively]. GFJ, orange juice, and furanocoumarin-free GFJ did not differ significantly (P > 0.09) in median time to reach maximum plasma concentration [2.5 (1.5-6), 2.8 (1.5-4), and 2.5 (2-6) h, respectively] or terminal half-life [6.6 (4.2-13.6), 7.8 (4.4-13.2), and 6.8 (2.6-14.4) h, respectively]. CONCLUSION: Furanocoumarins are the active ingredients in GFJ responsible for enhancing the systemic exposure of felodipine and probably other CYP3A4 substrates that undergo extensive intestinal first-pass metabolism.


Asunto(s)
Bebidas/análisis , Citrus paradisi/química , Felodipino/farmacocinética , Frutas/química , Furocumarinas/análisis , Furocumarinas/farmacología , Adulto , Células CACO-2 , Citocromo P-450 CYP3A , Inhibidores Enzimáticos del Citocromo P-450 , Interacciones de Drogas , Inhibidores Enzimáticos , Felodipino/sangre , Femenino , Furocumarinas/química , Humanos , Intestinos/ultraestructura , Masculino , Microsomas/enzimología
10.
Toxicology ; 207(1): 149-63, 2005 Feb 01.
Artículo en Inglés | MEDLINE | ID: mdl-15590130

RESUMEN

Phthalate esters belong to a large class of compounds known as peroxisome proliferators (PP). PP include chemicals that activate different subtypes of the peroxisome proliferator-activated receptor (PPAR) family. The ability of phthalate esters and their metabolites to activate responses through different PPAR subtypes is not fully characterized. We investigated the ability of two phthalate esters di-(2-ethylhexyl) phthalate (DEHP) and di-n-butyl phthalate (DBP) and selected metabolites to activate PPAR (alpha, beta/delta, gamma) using a transient transfection assay. The monoester of DEHP, mono-(2-ethylhexyl) phthalate (MEHP) activated all three subtypes of PPAR, but preferentially activated PPARalpha. A second metabolite of DEHP, 2-ethylhexanoic acid (2-EHXA) was a weaker activator of all three subtypes. DBP, but not the primary metabolite mono-n-butyl phthalate weakly activated all three PPAR subtypes. MEHP and DBP but not DEHP and MBP interacted directly with human PPARalpha and PPARgamma as determined by scintillation proximity assays. Both DEHP and DBP activated expression of PP-inducible gene products in wild-type but not PPARalpha-null mice suggesting that both of these phthalates exert their effects by activation of PPARalpha in vivo. The preferential activation of PPARalpha by phthalate ester metabolites suggests that these phthalates mediate their toxic effects in rodent liver in a manner indistinguishable from other PP.


Asunto(s)
Contaminantes Ambientales/metabolismo , Contaminantes Ambientales/toxicidad , Hígado/efectos de los fármacos , PPAR alfa/metabolismo , Ácidos Ftálicos/metabolismo , Ácidos Ftálicos/toxicidad , Acil-CoA Oxidasa/biosíntesis , Animales , Western Blotting , Línea Celular Tumoral , Relación Dosis-Respuesta a Droga , Inducción Enzimática/efectos de los fármacos , Humanos , Metabolismo de los Lípidos , Hígado/enzimología , Hígado/metabolismo , Ratones , Ratones Noqueados , Estructura Molecular , PPAR alfa/genética , PPAR delta/genética , PPAR delta/metabolismo , PPAR gamma/genética , PPAR gamma/metabolismo , PPAR-beta/genética , PPAR-beta/metabolismo , Unión Proteica , Ratas , Activación Transcripcional/efectos de los fármacos
11.
Toxicology ; 204(2-3): 109-21, 2004 Nov 15.
Artículo en Inglés | MEDLINE | ID: mdl-15388238

RESUMEN

Peroxisome proliferators (PP) are a large class of structurally diverse chemicals that mediate their effects in the liver mainly through the peroxisome proliferator-activated receptor alpha (PPARalpha). Exposure to some PP results in alterations of steroid levels that may be mechanistically linked to adverse effects in reproductive organs. We hypothesized that changes in steroid levels after PP exposure are due to alterations in the levels of P450 enzymes that hydroxylate testosterone and estrogen. In testosterone hydroxylase assays, exposure to the PP, WY-14,643 (WY), gemfibrozil or di-n-butyl phthalate (DBP) led to compound-specific increases in 6beta and 16beta-testosterone and androstenedione hydroxylase activities and decreases in 16alpha, 2alpha-hydroxylase activities by all three PP. The decreases in 16alpha and 2alpha-testosterone hydroxylase activity can be attributed to a 2alpha and 16alpha- testosterone hydroxylase, CYP2C11, which we previously showed was dramatically down-regulated in these same tissues (Corton et al., 1998; Mol. Pharmacol. 54, 463-473). To explain the increases in 6beta- and 16beta-testosterone hydroxylase activities, we examined the expression of P450 family members known to carry out these functions. Alterations in the 6beta-testosterone hydroxylases CYP3A1, CYP3A2 and the 16beta-testosterone hydroxylase, CYP2B1 were observed after exposure to some PP. The male-specific estrogen sulfotransferase was down-regulated in rat liver after exposure to all PP. The mouse 6beta-testosterone hydroxylase, Cyp3a11 was down-regulated by WY in wild-type but not PPARalpha-null mice. In contrast, DEHP increased Cyp3a11 in both wild-type and PPARalpha-null mice. These studies demonstrate that PP alter the expression and activity of a number of enzymes which regulate levels of sex steroids. The changes in these enzymes may help explain why exposure to some PP leads to adverse effects in endocrine tissues that produce or are the targets of sex hormones.


Asunto(s)
Hormonas Esteroides Gonadales/metabolismo , Microsomas Hepáticos/enzimología , Proliferadores de Peroxisomas/farmacología , Receptores Citoplasmáticos y Nucleares/metabolismo , Factores de Transcripción/metabolismo , Animales , Femenino , Masculino , Ratones , Ratones Noqueados , Microsomas Hepáticos/efectos de los fármacos , Ratas , Ratas Endogámicas F344 , Ratas Sprague-Dawley , Receptores Citoplasmáticos y Nucleares/deficiencia , Esteroide 16-alfa-Hidroxilasa/metabolismo , Sulfotransferasas/metabolismo , Factores de Transcripción/deficiencia
12.
Toxicology ; 203(1-3): 41-8, 2004 Oct 15.
Artículo en Inglés | MEDLINE | ID: mdl-15363580

RESUMEN

Peroxisome proliferators (PP) are a large class of structurally diverse chemicals that mediate their effects in the liver mainly through the peroxisome proliferator-activated receptor alpha (PPARalpha). Exposure to PP results in down-regulation of CYP2C family members under control of growth hormone and sex steroids including CYP2C11 and CYP2C12. We hypothesized that PP exposure would also lead to similar changes in CYP2C7, a retinoic acid and testosterone hydroxylase. CYP2C7 gene expression was dramatically down-regulated in the livers of rats treated for 13 weeks by WY-14,643 (WY; 500 ppm) or gemfibrozil (GEM; 8000 ppm). In the same tissues, exposure to WY and GEM and to a lesser extent di-n-butyl phthalate (20,000 ppm) led to decreases in CYP2C7 protein levels in both male and female rats. An examination of the time and dose dependence of CYP2C7 protein changes after PP exposure revealed that CYP2C7 was more sensitive to compound exposure compared to other CYP2C family members. Protein expression was decreased after 1, 5 and 13 weeks of PP treatment. CYP2C7 protein expression was completely abolished at 5 ppm WY, the lowest dose tested. GEM and DBP exhibited dose-dependent decreases in CYP2C7 protein expression, becoming significant at 1000 ppm or 5000 ppm and above, respectively. These results show that PP exposure leads to changes in CYP2C7 mRNA and protein levels. Thus, in addition to known effects on steroid metabolism, exposure to PP may alter retinoic acid metabolism.


Asunto(s)
Sistema Enzimático del Citocromo P-450/metabolismo , Receptores Activados del Proliferador del Peroxisoma/fisiología , Animales , Anticuerpos Bloqueadores/química , Biotransformación/fisiología , Northern Blotting , Western Blotting , Familia 2 del Citocromo P450 , Dibutil Ftalato/farmacología , Regulación hacia Abajo/efectos de los fármacos , Femenino , Gemfibrozilo/farmacología , Hígado/efectos de los fármacos , Hígado/enzimología , Masculino , Pirimidinas/farmacología , Ratas , Ratas Endogámicas F344 , Ratas Sprague-Dawley , Caracteres Sexuales
13.
Biochemistry ; 42(22): 6696-708, 2003 Jun 10.
Artículo en Inglés | MEDLINE | ID: mdl-12779324

RESUMEN

Patatin is a nonspecific lipid acyl hydrolase that accounts for approximately 40% of the total soluble protein in mature potato tubers, and it has potent insecticidal activity against the corn rootworm. We determined the X-ray crystal structure of a His-tagged variant of an isozyme of patatin, Pat17, to 2.2 A resolution, employing SeMet multiwavelength anomalous dispersion (MAD) phasing methods. The patatin crystal structure has three molecules in the asymmetric unit, an R-factor of 22.0%, and an R(free) of 27.2% (for 10% of the data not included in the refinement) and includes 498 water molecules. The structure notably revealed that patatin has a Ser-Asp catalytic dyad and an active site like that of human cytosolic phospholipase A(2) (cPLA(2)) [Dessen, A., et al. (1999) Cell 97, 349-360]. In addition, patatin has a folding topology related to that of the catalytic domain of cPLA(2) and unlike the canonical alpha/beta-hydrolase fold. The structure confirms our site-directed mutagenesis and bioactivity data that initially suggested patatin possessed a Ser-Asp catalytic dyad. Alanine-scanning mutagenesis revealed that Ser77 and Asp215 were critical for both esterase and bioactivity, consistent with prior work implicating a Ser residue [Strickland, J. H., et al. (1995) Plant Physiol. 109, 667-674] and a Ser-Asp dyad [Hirschberg, H. J. H. B., et al. (2001) Eur. J. Biochem. 268, 5037-5044] in patatin's catalytic activity. The crystal structure aids the understanding of other structure-function relationships in patatin. Patatin does not display interfacial activation, a hallmark feature of lipases, and this is likely due to the fact that it lacks a flexible lid that can shield the active site.


Asunto(s)
Ácido Aspártico/metabolismo , Hidrolasas de Éster Carboxílico/química , Hidrolasas de Éster Carboxílico/metabolismo , Proteínas de Plantas/química , Proteínas de Plantas/metabolismo , Serina/metabolismo , Alanina/genética , Sustitución de Aminoácidos/genética , Animales , Ácido Aspártico/genética , Hidrolasas de Éster Carboxílico/genética , Hidrolasas de Éster Carboxílico/farmacología , Dominio Catalítico/genética , Clonación Molecular , Escarabajos/efectos de los fármacos , Cristalografía por Rayos X , Humanos , Isoenzimas/química , Isoenzimas/genética , Isoenzimas/metabolismo , Isoenzimas/farmacología , Larva , Modelos Moleculares , Mutagénesis Sitio-Dirigida , Fosfolipasas A/genética , Pichia/metabolismo , Proteínas de Plantas/genética , Proteínas de Plantas/farmacología , Estructura Secundaria de Proteína , Serina/genética
SELECCIÓN DE REFERENCIAS
DETALLE DE LA BÚSQUEDA