RESUMEN
Cognitively demanding experiences, including complex skill acquisition and processing, have been shown to induce brain adaptations, at least at the macroscopic level, e.g. on brain volume and/or functional connectivity. However, the neurobiological bases of these adaptations, including at the cellular level, are unclear and understudied. Here we use bilingualism as a case study to investigate the metabolic correlates of experience-based brain adaptations. We employ Magnetic Resonance Spectroscopy to measure metabolite concentrations in the basal ganglia, a region critical to language control which is reshaped by bilingualism. Our results show increased myo-Inositol and decreased N-acetyl aspartate concentrations in bilinguals compared to monolinguals. Both metabolites are linked to synaptic pruning, a process underlying experience-based brain restructuring. Interestingly, both concentrations correlate with relative amount of bilingual engagement. This suggests that degree of long-term cognitive experiences matters at the level of metabolic concentrations, which might accompany, if not drive, macroscopic brain adaptations.
Asunto(s)
Encéfalo/fisiología , Cognición , Multilingüismo , Encéfalo/metabolismo , Humanos , Procesamiento de Imagen Asistido por Computador , Imagen por Resonancia MagnéticaRESUMEN
BACKGROUND AND PURPOSE: Parkinson's disease (PD) is usually diagnosed clinically from classical motor symptoms, while definitive diagnosis is made postmortem, based on the presence of Lewy bodies and nigral neuron cell loss. α-Synuclein (ASYN), the main protein component of Lewy bodies, clearly plays a role in the neurodegeneration that characterizes PD. Additionally, mutation in the SNCA gene or copy number variations are associated with some forms of familial PD. Here, the objective of the study was to evaluate whether olesoxime, a promising neuroprotective drug can prevent ASYN-mediated neurotoxicity. EXPERIMENTAL APPROACH: We used here a novel, mechanistically approachable and attractive cellular model based on the inducible overexpression of human wild-type ASYN in neuronally differentiated human neuroblastoma (SHSY-5Y) cells. This model demonstrates gradual cellular degeneration, coinciding temporally with the appearance of soluble and membrane-bound ASYN oligomers and cell death combining both apoptotic and non-apoptotic pathways. KEY RESULTS: Olesoxime fully protected differentiated SHSY-5Y cells from cell death, neurite retraction and cytoplasmic shrinkage induced by moderate ASYN overexpression. This protection was associated with a reduction in cytochrome c release from mitochondria and caspase-9 activation suggesting that olesoxime prevented ASYN toxicity by preserving mitochondrial integrity and function. In addition, olesoxime displayed neurotrophic effects on neuronally differentiated SHSY-5Y cells, independent of ASYN expression, by promoting their differentiation. CONCLUSIONS AND IMPLICATIONS: Because ASYN is a common underlying factor in many cases of PD, olesoxime could be a promising therapy to slow neurodegeneration in PD.
Asunto(s)
Colestenonas/farmacología , Neuronas/efectos de los fármacos , Fármacos Neuroprotectores/farmacología , alfa-Sinucleína/metabolismo , Caspasas/metabolismo , Línea Celular Tumoral , Supervivencia Celular/efectos de los fármacos , Citocromos c/metabolismo , Humanos , Neuronas/citología , Neuronas/metabolismoRESUMEN
The importance of preventive and population-based principles in clinical practice is widely acknowledged. The challenge of imparting these principles in either undergraduate or postgraduate medical education has, however, not been fully met. The necessary skills are provided comprehensively by preventive medicine residency programs, but at the expense of clinical training. Sequential residencies in primary care and preventive medicine, the currently available means of obtaining thorough preparation in both clinical and population-based principles, represent an inefficient, generally unappealing, and non-integrated approach. In response to these concerns, and in an effort to make preventive medicine training appeal to a wider audience, the authors developed and implemented a residency program fully integrating internal and preventive medicine. The program meets, and generally exceeds, the requirements of both specialty boards over a four-year period. The program provides extensive training in clinical, preventive, and public health skills, along with case management and cost-effective care, conferring the MPH degree and leading to dual board eligibility. The model is ideally wed to the demands of the modern health care environment in the United States, is extremely attractive to applicants, and may warrant replication both to train academic and administrative leaders and to raise the standards of preventive and public health practice in primary care.
Asunto(s)
Medicina Interna/educación , Internado y Residencia , Medicina Preventiva/educación , Acreditación , Personal Administrativo , Manejo de Caso , Competencia Clínica , Análisis Costo-Beneficio , Docentes Médicos , Humanos , Internado y Residencia/clasificación , Internado y Residencia/organización & administración , Modelos Educacionales , Desarrollo de Programa , Salud Pública/educación , Salud Pública/normas , Criterios de Admisión Escolar , Consejos de Especialidades , Apoyo a la Formación Profesional , Estados UnidosRESUMEN
Currently there is controversial evidence that suggests that the accepted incidence of atrophic gastritis of 1.2 to 3.3% in patients with Helicobacter pylori gastritis may be increased by the long-term suppression of acid by a proton pump inhibitor (omeprazole). The purpose of this study is to show whether lesser forms of acid suppression by antacids or H2 receptor antagonists may have an influence on the development of atrophic gastritis. The authors recently reported a study in which a cohort of 36 patients with symptoms of dyspepsia were followed clinically for a period of 7 to 19 years. In that report all subjects underwent upper endoscopy with two biopsy specimens each from the antrum and fundus, on at least two occasions, 7 to 19 years apart. A diagnosis of atrophic gastritis was based on the interpretation of these biopsies by two gastrointestinal pathologists. The presence of H. pylori colonization was determined by tissue sampling and by a campylobacter-like organisms test of the antrum. Of the 36 patients in the authors' previous report, 33 had adequate baseline and follow-up data on medications consumed throughout the period of the study. In their current report they now present the findings of a retrospective review in which they correlate the presence of atrophic gastritis with the sole use of antacids and H2 receptor antagonists throughout the period of the study. In the cohort of 33 patients evaluated from the previous report, the authors found that atrophic gastritis had developed in all 28 patients positive for H. pylori, and in none of the 5 patients negative for H. pylori (p < 0.0001). A retrospective analysis of this previously studied cohort of 33 patients revealed that the use of antacids and H2 receptor antagonists did not predict the development of atrophic gastritis in either H. pylori-negative or -positive subjects. In a retrospective analysis of a cohort of 33 patients followed for an average of 11.7 years, atrophic gastritis developed in H. pylori-positive but not in H. pylori-negative subjects, irrespective of the use and duration of antacids or H2 receptor antagonists.
Asunto(s)
Antiácidos/efectos adversos , Gastritis Atrófica/inducido químicamente , Gastritis/tratamiento farmacológico , Infecciones por Helicobacter/tratamiento farmacológico , Helicobacter pylori , Antagonistas de los Receptores H2 de la Histamina/efectos adversos , Anciano , Antiácidos/uso terapéutico , Estudios de Cohortes , Femenino , Estudios de Seguimiento , Gastritis/microbiología , Gastritis Atrófica/epidemiología , Antagonistas de los Receptores H2 de la Histamina/uso terapéutico , Humanos , Incidencia , Masculino , Persona de Mediana Edad , Estudios Retrospectivos , Factores de TiempoAsunto(s)
Mortalidad del Niño , Demografía , Mortalidad Infantil , Asistencia Pública , Práctica de Salud Pública , Salud Pública , Condiciones Sociales , Niño , Mortalidad del Niño/etnología , Mortalidad del Niño/historia , Preescolar , Francia/etnología , Historia del Siglo XIX , Historia del Siglo XX , Humanos , Lactante , Mortalidad Infantil/etnología , Mortalidad Infantil/historia , Recién Nacido , Rol Profesional/historia , Rol Profesional/psicología , Asistencia Pública/economía , Asistencia Pública/historia , Asistencia Pública/legislación & jurisprudencia , Salud Pública/economía , Salud Pública/educación , Salud Pública/historia , Salud Pública/legislación & jurisprudencia , Práctica de Salud Pública/economía , Práctica de Salud Pública/historia , Práctica de Salud Pública/legislación & jurisprudencia , Opinión Pública , Condiciones Sociales/economía , Condiciones Sociales/historia , Condiciones Sociales/legislación & jurisprudencia , Problemas Sociales/economía , Problemas Sociales/etnología , Problemas Sociales/historia , Problemas Sociales/legislación & jurisprudencia , Problemas Sociales/psicología , Apoyo Social , Estadística como Asunto/economía , Estadística como Asunto/educación , Estadística como Asunto/historia , Estadística como Asunto/legislación & jurisprudenciaRESUMEN
The role of the excretion of dietary cholesterol in the hypocholesterolaemic effect of chronic fish oil feeding in rats was investigated. The hepatic uptake and processing of [3H]cholesterol carried in chylomicrons derived from fish oil was studied in vivo in rats fed a low fat diet or a diet supplemented with fish oil for 21 days. In addition, the effects of the fish oil diet on cholesterol esterification, cholesteryl ester hydrolysis, bile acid synthesis and biliary lipid secretion were determined. In rats fed the fish oil as compared to the low fat diet, the uptake of [3H]cholesterol from the blood and its secretion into bile as bile acids was significantly slower, and this was entirely due to a decrease in the bile acid fraction. Biliary bile acid mass secretion was unchanged by fish oil feeding, while biliary cholesterol and phospholipid secretion was increased. No significant differences were observed either in the expression of mRNA for cholesterol 7alpha hydroxylase or the secretion of bile acids into bile after 20 h biliary drainage between the fish oil and low fat diet groups, suggesting that bile acid synthesis is not affected. These results indicate that the access of chylomicron cholesterol to the hepatic substrate pool for bile acid formation is decreased in the fish oil fed rats, and this, together with its slower uptake from the blood, accounts for the retardation of its excretion via the bile. Thus, the hypocholesterolemic effect of dietary fish oil in rats is not due to more rapid metabolism of cholesterol originating from the diet.
Asunto(s)
Colesterol en la Dieta/orina , Colesterol/sangre , Grasas Insaturadas en la Dieta/farmacología , Aceites de Pescado/farmacología , Animales , Bilis/metabolismo , Bilis/fisiología , Quilomicrones/farmacología , Dieta con Restricción de Grasas , Inyecciones Intravenosas , Metabolismo de los Lípidos , Hígado/enzimología , Hígado/metabolismo , Masculino , ARN Mensajero/metabolismo , Ratas , Ratas Wistar , Triglicéridos/sangreRESUMEN
There is a paucity of data on the long-term behavior of dyspepsia, endoscopic findings, and gastroduodenal histology in patients with or without Helicobacter pylori colonization. We evaluated these parameters during a period of 7 to 19 years (average, 12.3 years) by baseline and follow-up studies. In 36 patients studied, the pattern of gastroduodenal dyspepsia and esophagogastroduodenoscopy findings remained essentially unchanged in 67% and 56% respectively. Dyspepsia patterns did not correlate significantly with either endoscopic or histologic findings, including the severity or location of gastritis in the fundus or antrum, or the presence or absence of H. pylori gastritis. Of 36 patients with adequate biopsies of the fundus and antrum, H. pylori colonization with gastritis was present in 73% but not in 27%. Progression to various degrees of atrophic gastritis was noted in 100% with, and in none without, H. pylori gastritis. In the fundus, atrophy progressed from 14% to 56%, but intestinal metaplasia did not change. In the antrum, atrophy increased from 22% to 64% and intestinal metaplasia increased from 17% to 36%. No patient demonstrated dysplasia, but severe atrophy was seen in the fundus (6%) and antrum (11%). Only two patients (5%) had severe loss of glandular elements and very low pepsinogen I, and thus can be considered to have developed advanced gastric atrophy.
Asunto(s)
Endoscopía del Sistema Digestivo , Mucosa Gástrica/patología , Infecciones por Helicobacter/diagnóstico , Gastropatías/diagnóstico , Adulto , Anciano , Anciano de 80 o más Años , Anticuerpos Antibacterianos/análisis , Estudios de Cohortes , Recuento de Colonia Microbiana , Femenino , Gastrectomía , Mucosa Gástrica/microbiología , Gastritis Atrófica/sangre , Gastritis Atrófica/diagnóstico , Gastritis Atrófica/microbiología , Infecciones por Helicobacter/etiología , Infecciones por Helicobacter/cirugía , Helicobacter pylori/crecimiento & desarrollo , Helicobacter pylori/inmunología , Helicobacter pylori/aislamiento & purificación , Humanos , Masculino , Persona de Mediana Edad , Pepsinógenos/sangre , Gastropatías/sangre , Gastropatías/microbiología , Úlcera Gástrica/diagnóstico , Úlcera Gástrica/microbiología , Úlcera Gástrica/cirugíaRESUMEN
The aim of this study was to determine whether the higher vertebral bone mass in women receiving hormone replacement therapy (HRT) is confined to the trabecular rich vertebral body rather than the predominantly cortical posterior processes, and to determine whether the protective effect of HRT at the proximal femur, a predominantly cortical site, is less than at the spine. Bone mass (g) of the third lumbar vertebra (total, vertebral body and posterior processes, measured by lateral scanning), and bone mineral density (g/cm2) of the femoral neck, Ward's triangle, and trochanter were measured using dual X-ray absorptiometry in a cross-sectional study of 71 women receiving HRT for 5.7 +/- 0.4 years (mean +/- SEM), ranging from 1 to 21 years, 69 age-matched controls, and 42 premenopausal controls aged 20 to 40 years. Relative to untreated postmenopausal controls, total bone mass of the third lumbar vertebra (body plus posterior processes) by postero-anterior (PA) scanning was 0.4 +/- 0.1 SD or 9.6 +/- 3.0% higher in HRT treated women (p < 0.01). By lateral scanning, total bone mass was higher than age-matched controls (z score 0.4 +/- 0.1 SD or 11.2 +/- 3.4%, p < 0.01). This difference was confined to the vertebral body (z score 0.6 +/- 0.1 SD, p < 0.001), which was 17.1 +/- 3.3% higher than in age-matched controls (p < 0.001). Bone mass of the posterior processes was no higher [z score 0.1 +/- 0.1, not significant (NS)]. The deficit at the vertebral body in HRT-treated women, relative to premenopausal controls, was half the deficit at the vertebral body in untreated postmenopausal women (t score -0.7 +/- 0.1 vs. -1.4 +/- 0.1 SD, respectively; p < 0.001) but no less at the posterior processes (t score -1.6 +/- 0.2 vs. -1.9 +/- 0.2 SD, respectively; NS). Similarly, the deficit in the vertebral body in the HRT treated group was half the deficit at their posterior processes (t score -0.7 +/- 0.1 SD vs. -1.6 +/- 0.2, respectively; p < 0.001). In HRT-treated women, bone mass diminished significantly with age at the posterior processes (r = -0.31, p < 0.01), but not at the vertebral body (r = -0.21, p = 0.07). Bone mass diminished significantly with age at the vertebral body and posterior processes in untreated women (r = -0.55, p < 0.001; r = -0.45, p < 0.001, respectively). Bone density (g/cm2) diminished at all femoral sites with advancing age in HRT-treated women. A protective effect was seen at the femoral neck and Ward's triangle, but not trochanter (z score 0.2 +/- 0.1, p = 0.06; 0.3 +/- 0.1, p < 0.05; 0.0 +/- 0.1, NS, respectively). In conclusion, the protective effect of HRT against bone loss at the vertebral body, the site of fracture in osteoporosis, may be underestimated by PA scanning. The greater benefit at the vertebral body, and more modest effect at the proximal femur, suggests that HRT may be a more effective means of reducing the risk of spine than hip fractures.
Asunto(s)
Densidad Ósea/efectos de los fármacos , Terapia de Reemplazo de Estrógeno , Fémur/efectos de los fármacos , Vértebras Lumbares/efectos de los fármacos , Osteoporosis Posmenopáusica/prevención & control , Absorciometría de Fotón , Administración Cutánea , Adulto , Anciano , Densidad Ósea/fisiología , Estudios Transversales , Preparaciones de Acción Retardada , Estradiol/análogos & derivados , Estradiol/uso terapéutico , Estrógenos Conjugados (USP)/uso terapéutico , Femenino , Fémur/diagnóstico por imagen , Humanos , Vértebras Lumbares/diagnóstico por imagen , Persona de Mediana EdadRESUMEN
The validity of the bone mineral density (BMD) measurement depends on its accuracy as a predictor of the breaking strength of bone. As the breaking strength is proportional to the square of the apparent density, a small error in the calculation of BMD may result in a larger error in the predicted bone strength. The aims of this study were (i) to determine whether inaccuracies in the measurement of the dimensions, projected area, and volume of the vertebral body (used to derive the areal and volumetric BMD) result in errors in the predicted breaking strength and (ii) to compare the accuracy, sensitivity, and specificity of bone mineral content (BMC), areal BMD, volumetric BMD, and volumetric bone mineral apparent density (BMAD) as surrogates of bone strength. We measured the BMC (by densitometry), dimensions and volume (using calipers, densitometry, the Carter et al. and Peel and Eastell methods), and breaking strength (using the Instron 1114 apparatus, Newtons, N) of 22 vertebral body specimens. All methods resulted in errors in height, width, and depth between -11.3 +/- 1.0 and 30.4 +/- 1.8% relative to the "gold" standard caliper method. The vertebral body volume (of 38.0 +/- 1.2 cm3) measured by submersion was used as the gold standard to derive the volumetric BMD gold standard (of 0.162 +/- 0.01 g/cm3). All methods, except the Peel and Eastell method, resulted in errors ranging between -10.7 +/- 1.5 and 56.9 +/- 3.4% in vertebral body volume and -35.6 +/- 1.5 to 12.6 +/- 1.8% in volumetric BMD (all p < 0.0005). The same absolute value for volumetric BMD predicted a breaking strength that differed according to the method used to derive BMD. For example, a volumetric BMD of 0.162 g/cm3 predicted a breaking strength of 6208 N (submersion method), 5473 N (caliper method), 6095 N (Peel and Eastell method), 7697 N (DXA method), and 9470 N (Carter et al. method). The mean volumetric BMD derived by each method differed (0.181, 0.165, 0.133, and 0.104 g/cm3, respectively). However, all were accurate; each predicted a similar breaking strength (6177, 6217, 6209, and 6221 N respectively). Likewise, breaking strengths predicted by the mean BMC, areal BMD by calipers, and areal BMD by dual-energy X-ray absorptiometry (DXA) were 6267, 6214, and 6244 N, respectively. The methods were equally sensitive; a 1 standard deviation (SD) decrease in volumetric BMD resulted in a similar decrease in the breaking strength of 1818 (caliper), 2080 (Peel and Eastell), 2001 (DXA), and 1625 N (BMAD by Carter et al). A 1 SD decrease in BMC, areal BMD (using calipers) and areal BMD (using DXA) predicted a decrease in the breaking strength of 2019, 1738, and 1825 N, respectively. All methods were equally specific; the variance in bone strength explained by bone mass did not differ for volumetric BMD (38-61% depending on the method), BMC (58%), or areal BMD (48%). In conclusion, despite errors in the measurement of the dimensions of the vertebral body, bone mass, areal, and volumetric bone density are equally accurate, sensitive, and specific surrogates of the breaking strength of bone in vitro.
Asunto(s)
Densidad Ósea/fisiología , Vértebras Lumbares/fisiología , Fracturas de la Columna Vertebral/fisiopatología , Absorciometría de Fotón , Adulto , Anciano , Anciano de 80 o más Años , Análisis de Varianza , Fuerza Compresiva/fisiología , Femenino , Humanos , Persona de Mediana Edad , Valor Predictivo de las Pruebas , Reproducibilidad de los Resultados , Sensibilidad y EspecificidadRESUMEN
I am presenting my view on how to approach the difficult subject of dyspepsia, based on my personal experience and the writings and teachings of Howard M. Spiro. Symptoms arising from the esophagus, and called esophageal dyspepsia, are separated from symptoms arising from the stomach, designated as gastroduodenal dyspepsia. The holistic approach to patients with dyspepsia, and designated Spiro syndrome, is the main purpose of this report. I am introducing a newly defined classification, and criteria, using an interchangeable, standardized nomenclature, to be used by the clinician, endoscopist, and pathologist for diagnosing and managing the causes of gastroduodenal dyspepsia. There are five clinical/endoscopic/histological categories to be considered as possible causes of gastroduodenal dyspepsia. Often these entities are found to be asymptomatic, or a combination may cause symptoms: (1) idiopathic dyspepsia--normal endoscopy and histology; (2) congestive gastropathy/duodenopathy; (3) gastritis/duodenitis; (4) peptic ulcer crater, and (5) gastric cancer. I believe this holistic, unifying approach to diagnosis and management of dyspepsia will enhance the communication between physicians and help standardize the terminology for clinical investigation.
Asunto(s)
Enfermedades Duodenales/complicaciones , Dispepsia/diagnóstico , Dispepsia/terapia , Gastropatías/complicaciones , Enfermedades Duodenales/diagnóstico , Enfermedades Duodenales/terapia , Dispepsia/etiología , Endoscopía del Sistema Digestivo , Humanos , Gastropatías/diagnóstico , Gastropatías/terapia , Resultado del TratamientoRESUMEN
The Yale-Affiliated Gastroenterology Program (YAGP) originated in 1965 from the informal arrangements of two gastroenterologists, one university based and the other in a community hospital. Conceived at a time when there was little central authority, either on a national or on a hospital/medical school level, its links were forged by the personal relationships of its directors. The process of growth remained informal and flexible enough for the directors to meet the special requirements of their own community and hospital. YAGP provided an important model for improving medical care and education in community hospitals since it addressed personnel needs, contributed to the education of physicians, and fostered clinical research in digestive diseases. YAGP evolved its own standards and its own accreditation mechanism, but faltered when the Accreditation Committee on Graduate Medical Education provided national rather than local criteria. Increased controls by hospitals and medical schools led to more formal ties and programs, and YAGP ceased to matter. Still, there may be lessons from what was in its time an innovation, on a local and state level rather than on a national level.
Asunto(s)
Redes Comunitarias/organización & administración , Educación Médica , Gastroenterología/educación , Hospitales Comunitarios , Facultades de Medicina , Acreditación , ConnecticutRESUMEN
Ruta graveolens utilizes anthranilate synthase (AS) for the synthesis both of tryptophan in primary metabolism and acridone alkaloids in secondary metabolism. AS has been purified from plants and cell cultures of R. graveolens 670- and 1700-fold, respectively. Glutamine- and ammonia-dependent AS activities were strictly co-purified in all steps. Through cDNA cloning and complementation of Escherichia coli deletion mutants defective for AS, it is shown that young Ruta plants express two genes for functional AS alpha subunits, AS alpha 1 and AS alpha 2. The data indicate that AS alpha from Ruta requires an AS beta subunit with a native molecular weight of 60-65 kDa for the glutamine-dependent reaction. Protein synthesized in vitro from cloned cDNA is processed upon import into isolated chloroplasts, indicating that mature AS alpha subunits are active in plastids in vivo. AS alpha 1 and AS alpha 2 are constitutively expressed in Ruta cell cultures, but AS alpha 1 steady-state mRNA levels are increased 100-fold 6 h subsequent to elicitation whereas AS alpha 2 expression remains constitutive. Increased AS alpha 1 transcription corresponds to elicitor-induced alkaloid accumulation. The data indicate that Ruta regulates anthranilate flux into primary and secondary metabolism through differential regulation of AS genes specific to these pathways.
Asunto(s)
Antranilato Sintasa/genética , Plantas/enzimología , Plantas/genética , Secuencia de Aminoácidos , Antranilato Sintasa/química , Antranilato Sintasa/aislamiento & purificación , Arabidopsis/genética , Clonación Molecular , ADN Complementario/genética , ADN de Plantas/genética , Precursores Enzimáticos/metabolismo , Escherichia coli/genética , Regulación Enzimológica de la Expresión Génica , Regulación de la Expresión Génica de las Plantas , Datos de Secuencia Molecular , Peso Molecular , Plastidios/enzimología , Conformación Proteica , ARN Mensajero/genética , ARN Mensajero/metabolismo , ARN de Planta/genética , ARN de Planta/metabolismo , Proteínas Recombinantes/genética , Proteínas Recombinantes/aislamiento & purificación , Proteínas Recombinantes/metabolismo , Homología de Secuencia de AminoácidoRESUMEN
Speculation continues that ulcerative colitis is an autoimmune disorder that is frequently associated with other diseases with a similar underlying pathogenic mechanism. In 1965 we reported a patient with ulcerative colitis and scleroderma in support of this hypothesis. Now we supply a follow-up of over 30 years to describe how each disease acted independently, evidence, we believe, that the association was primarily fortuitous.
Asunto(s)
Colitis Ulcerosa/complicaciones , Esclerodermia Sistémica/complicaciones , Adulto , Colitis Ulcerosa/diagnóstico por imagen , Humanos , Masculino , Persona de Mediana Edad , RadiografíaRESUMEN
A uridinediphosphateglucose:thiohydroximate glucosyltransferase (EC 2.4.1.-) has been purified 3700-fold from Brassica napus L. seedlings. The enzyme catalyzes the formation of desulfoglucosinolates by transfer of glucose from UDP-glucose to thiohydroximates and is believed to be the second to last step involved in glucosinolate biosynthesis. The enzyme was purified to near homogeneity, exhibiting a single band by non-denaturing polyacrylamide gel electrophoresis (PAGE) and on sodium dodecyl sulfate-PAGE (M(r) 46,000) but showed multiple isoforms between pH 4.6 and 4.3 when resolved by IEF. The enzyme is stable at temperatures up to 30 degrees C for at least 1 h and shows maximum activity rates at pH 6.0 and has no absolute requirements for cations. The Km values for UDP-glucose and phenylacetothiohydroximate were calculated to be 0.46 and 0.05 mM, respectively. This enzyme possesses a high degree of specificity for the thiohydroximic functional group but little specificity for the associated side-chain groups. Similar enzyme activity has been detected in all other members of the Brassicaceae family tested and is believed to be a common thiohydroximate glucosylating enzyme present in these and other glucosinolate producing plants.
Asunto(s)
Brassica/enzimología , Glucosiltransferasas/aislamiento & purificación , Glucosinolatos/metabolismo , Glucosiltransferasas/metabolismo , Concentración de Iones de Hidrógeno , Punto Isoeléctrico , Metales , Peso Molecular , Proteínas de Plantas/aislamiento & purificación , Especificidad por SustratoRESUMEN
cDNA clones coding for flavonol 3- and 4'-sulfotransferases (STs) were isolated by antibody screening of a cDNA expression library produced from poly(A)+ RNA extracted from terminal buds of Flaveria chloraefolia. Sequence analysis revealed full-length cDNA clones with open reading frames of 933 and 960 base pairs, which encode polypeptides containing 311 and 320 amino acids, respectively. This corresponds to a molecular mass of 36,442 Da for the 3-ST and 37,212 Da for the 4'-ST. Expression of these clones in Escherichia coli led to the synthesis of beta-galactosidase-ST fusion proteins having the same substrate and position specificities as those for the 3- and 4'-flavonol ST enzymes isolated from the plant. Comparison of the deduced amino acid sequence of the two clones revealed an overall identity of 69% in 311 amino acid residues. The two flavonol STs of F. chloraefolia also shared significant sequence similarities with steroid and aryl STs found in animal tissues and with the senescence marker protein 2 isolated from rat liver, suggesting an evolutionary link between plant and animal STs.
Asunto(s)
Proteínas de Plantas/genética , Sulfotransferasas/genética , Secuencia de Aminoácidos , Animales , Secuencia de Bases , Bovinos , Clonación Molecular , ADN/genética , Escherichia coli/enzimología , Flavonoides , Flavonoles , Expresión Génica , Datos de Secuencia Molecular , Plantas/enzimología , Ratas , Alineación de Secuencia , Especificidad por Sustrato , Sulfotransferasas/metabolismoRESUMEN
This paper contains a description of the results of a two-year study of task-achievement, obsessive-compulsive, Type A traits, and job satisfaction within randomly selected groups of 499 public practice accountants in Ontario, Canada. The results supported the notion that this profession attracts and conditions personalities with task-oriented, order-driven, Type A characteristics. With the exception of those who were advanced partners, the majority of public practice accountants were only moderately job-satisfied and were reportedly not committed to staying in their present jobs until retirement.
Asunto(s)
Contabilidad , Trastorno de Personalidad Compulsiva/psicología , Empleo/psicología , Satisfacción en el Trabajo , Personalidad Tipo A , Adulto , Factores de Edad , Anciano , Interpretación Estadística de Datos , Femenino , Humanos , Masculino , Persona de Mediana Edad , Estrés PsicológicoRESUMEN
Dieulafoy's lesion is an often unrecognized cause of catastrophic upper gastrointestinal hemorrhage, typically seen in otherwise asymptomatic patients. Although the lesion is most often found in the stomach, it has rarely been reported to occur in the jejunum and duodenum. Endoscopic treatment has recently been attempted to arrest the bleeding from these lesions, when found in the stomach, with satisfactory results. We report a patient with a bleeding duodenal Dieulafoy lesion who was successfully treated with endoscopic injection of epinephrine (1:10,000) and electrocoagulation. Endoscopic treatment of Dieulafoy's lesion should be attempted before surgery and, as in other causes of acute nonvariceal hemorrhage, be considered the treatment of choice.