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INTRODUCTION: Today, primary care professionals' (PCPs) perspectives on hospital quality are unknown when evaluating hospital quality priorities. The aims of the present study were to identify key healthcare quality attributes from PCPs' perspective, to validate an instrument that measures PCPs' experiences of healthcare quality multidimensionally and to define hospital quality priorities based on PCPs' experiences. MATERIAL AND METHODS: Focus groups with PCPs were conducted to identify quality attributes through a qualitative in-depth analysis. A multicentre study of 18 hospitals was used to quantitatively assess construct, discriminant and criterion validity of the FlaQuM-Quickscan, an instrument that measures 'Healthcare quality for patients and kin' (part 1) and 'Healthcare quality for professionals' (part 2). To set quality priorities, scores on quality domains were analyzed descriptively and between-hospital variation was examined by evaluating differences in hospitals' mean scores on the quality domains using one-way Analysis of Variance (ANOVA). RESULTS: Identified key attributes largely corresponded with Lachman's multidimensional quality model. Including 'Communication' as a new quality domain was recommended. The FlaQuM-Quickscan was completed by 550 PCPs. Confirmatory factor analyses showed reasonable to good fit, except for the Root Mean Square Error of Approximation (RMSEA) in part 2. The 'Equity' domain scored the highest in parts 1 and 2. Domains 'Kin-centred care' and 'Accessibility and timeliness' scored the lowest in part 1 and 'Resilience' and 'Partnership and co-production' in part 2. Significant variation in hospitals' mean scores was observed for eleven domains in part 1 and sixteen domains in part 2. CONCLUSIONS: The results gained a better understanding of PCPs' perspective on quality. The FlaQuM-Quickscan is a valid instrument to measure PCPs' experiences of hospital quality. Identified priorities indicate that hospital management should focus on multifaceted quality strategies, including technical domains, person-and kin-centredness, core values and catalysts.
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Hospitales , Calidad de la Atención de Salud , Humanos , Análisis de Varianza , Grupos Focales , Atención Primaria de SaludRESUMEN
RESUMEN Objetivo: El objetivo fue definir los contenidos mínimos y sus indicadores de aplicación clínica en el currículo de cariología para las escuelas de odontología chilenas. Metodología: Basados en los 5 dominios curriculares internacionales, se elaboró un documento que define los contenidos e indicadores de aplicación clínica para la enseñanza de cariología en Chile. Posteriormente, profesores de cariología de 20 de 21 escuelas de odontología chilenas (95%), sesionaron para revisar, retroalimentar y elaborar el documento final, denominado "Listado de contenidos mínimos e indicadores de aplicación clínica" en cariología para estudiantes de pregrado de odontología en Chile. Resultados: Se definieron 23 contenidos y 31 indicadores de aplicación clínica para la enseñanza de la cariología. La cantidad de contenidos e indicadores separados por dominio fueron respectivamente: conocimiento de base: 5 y 7; riesgo/detección y diagnóstico: 6 y 6; toma de decisiones/manejo preventivo no operatorio: 5 y 5; decisión de tratamiento operatorio: 4 y 9 y cariología basada en la evidencia: 3 y 4. Conclusiones: Se definieron los contenidos mínimos que tributan a cada dominio y sus indicadores de aplicación clínica para la enseñanza de la cariología en Chile.
ABSTRACT: The objective: was to define the minimum contents and their indicators of clinical application in the cariology curriculum for the Chilean Dental Schools. Methodology: Based on the 5 international curricular domains, a document defining the contents and indicators of clinical application for the teaching of cariology in Chile was elaborated. Later, cariology professors from 20 out of the 21 Chilean Dentistry Schools (95%) met to review, feedback and elaborate the final document, called "List of minimum contents and indicators of clinical application" in cariology for undergraduate dentistry students in Chile. Results: Twenty-three contents and 31 indicators of clinical application for the teaching of cariology were agreed upon. The amount of contents and indicators separated by domain respectively were: basic knowledge: 5 and 7; risk/detection and diagnosis: 6 and 6; decision making/non-operative preventive management: 5 and 5; decision of operative treatment: 4 and 9 and evidence-based cariology: 3 and 4. Conclusions: The minimum contents for each domain and its clinical application indicators for the teaching of cariology in Chile were defined.
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Humanos , Facultades de Odontología , Caries Dental , Educación en Odontología , Competencia Profesional , ChileRESUMEN
The perilipin proteins enclose intracellular lipid droplets. We describe the mRNA expression of the five perilipins in human skeletal muscle in relation to fatty acid supply, exercise and energy balance. We observed that all perilipins were expressed in skeletal muscle biopsies with the highest mRNA levels of perilipin 2, 4 and 5. Cultured myotubes predominantly expressed perilipin 2 and 3. In vitro, incubation of myotubes with fatty acids enhanced mRNA expression of perilipin 1, 2 and 4. In vivo, low fat diet increased mRNA levels of perilipin 3 and 4. Endurance training, but not strength training, enhanced the expression of perilipin 2 and 3. Perilipin 1 mRNA correlated positively with body fat mass, whereas none of the perilipins were associated with insulin sensitivity. In conclusion, all perilipins mRNAs were expressed in human skeletal muscle. Diet as well as endurance exercise modulated the expression of perilipins.
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Proteínas Portadoras/metabolismo , Ácidos Grasos/farmacología , Expresión Génica/efectos de los fármacos , Fibras Musculares Esqueléticas/metabolismo , Fosfoproteínas/metabolismo , ARN Mensajero/biosíntesis , Tejido Adiposo , Anciano , Proteínas Portadoras/genética , Técnicas de Cultivo de Célula , Dieta , Grasas de la Dieta/metabolismo , Metabolismo Energético/fisiología , Ejercicio Físico/fisiología , Femenino , Humanos , Resistencia a la Insulina , Masculino , Persona de Mediana Edad , Fibras Musculares Esqueléticas/citología , Fibras Musculares Esqueléticas/efectos de los fármacos , Especificidad de Órganos , Perilipina-1 , Fosfoproteínas/genética , Resistencia Física/fisiología , Isoformas de Proteínas/genética , Isoformas de Proteínas/metabolismo , Reacción en Cadena en Tiempo Real de la PolimerasaAsunto(s)
Farmacorresistencia Bacteriana , Pseudomonas aeruginosa/química , Pseudomonas aeruginosa/efectos de los fármacos , Antibacterianos/farmacología , Proteínas Bacterianas/genética , Proteínas Bacterianas/metabolismo , Biopelículas , Regulación Bacteriana de la Expresión Génica , Infecciones por Pseudomonas , Pseudomonas aeruginosa/genética , Pseudomonas aeruginosa/fisiología , Propiedades de SuperficieAsunto(s)
Anestésicos Locales/administración & dosificación , Terapia por Estimulación Eléctrica/veterinaria , Enfermedades del Sistema Nervioso/veterinaria , Procaína/administración & dosificación , Anestésicos Locales/uso terapéutico , Animales , Enfermedades del Sistema Nervioso/terapia , Procaína/uso terapéuticoRESUMEN
In humans, low peak bone mass is a significant risk factor for osteoporosis. We report that LRP5, encoding the low-density lipoprotein receptor-related protein 5, affects bone mass accrual during growth. Mutations in LRP5 cause the autosomal recessive disorder osteoporosis-pseudoglioma syndrome (OPPG). We find that OPPG carriers have reduced bone mass when compared to age- and gender-matched controls. We demonstrate LRP5 expression by osteoblasts in situ and show that LRP5 can transduce Wnt signaling in vitro via the canonical pathway. We further show that a mutant-secreted form of LRP5 can reduce bone thickness in mouse calvarial explant cultures. These data indicate that Wnt-mediated signaling via LRP5 affects bone accrual during growth and is important for the establishment of peak bone mass.
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Densidad Ósea/genética , Anomalías del Ojo/genética , Ojo/embriología , Osteoblastos/metabolismo , Osteoporosis/genética , Receptores de LDL/fisiología , Factor de Crecimiento Transformador beta , Proteínas de Pez Cebra , Proteínas Adaptadoras Transductoras de Señales , Adulto , Animales , Animales no Consanguíneos , Proteína Morfogenética Ósea 2 , Proteínas Morfogenéticas Óseas/farmacología , Células COS , Niño , Preescolar , Chlorocebus aethiops , Cromosomas Humanos Par 11/genética , Medios de Cultivo Condicionados/farmacología , ADN Complementario/genética , Proteínas Dishevelled , Femenino , Genes Recesivos , Heterocigoto , Humanos , Proteínas Relacionadas con Receptor de LDL , Proteína-5 Relacionada con Receptor de Lipoproteína de Baja Densidad , Masculino , Mesodermo/citología , Ratones , Ratones Endogámicos C57BL , Técnicas de Cultivo de Órganos , Fosfoproteínas/genética , Fosfoproteínas/fisiología , Proteínas/genética , Proteínas/fisiología , Proteínas Proto-Oncogénicas/genética , Proteínas Proto-Oncogénicas/fisiología , Receptores de LDL/deficiencia , Receptores de LDL/genética , Proteínas Recombinantes de Fusión/fisiología , Proteínas Recombinantes , Transducción de Señal , Cráneo/citología , Especificidad de la Especie , Células del Estroma/citología , Células del Estroma/efectos de los fármacos , Síndrome , Transfección , Proteínas Wnt , Proteína Wnt-5a , Proteína wnt2 , Proteína Wnt3 , Proteína Wnt4RESUMEN
Osteoporosis-pseudoglioma syndrome (OPS) is an autosomal recessive disorder characterized by severe juvenile-onset osteoporosis and congenital or juvenile-onset blindness. The pathogenic mechanism is not known. Clinical, biochemical, and microscopic analyses suggest that OPS may be a disorder of matrix homeostasis rather than a disorder of matrix structure. Consequently, identification of the OPS gene and its protein product could provide insights regarding common osteoporotic conditions, such as postmenopausal and senile osteoporosis. As a first step toward determining the cause of OPS, we utilized a combination of traditional linkage analysis and homozygosity mapping to assign the OPS locus to chromosome region 11q12-13. Mapping was accomplished by analyzing 16 DNA samples (seven affected individuals) from three different consanguineous kindreds. Studies in 10 additional families narrowed the candidate region, supported locus homogeneity, and did not detect founder effects. The OPS locus maps to a 13-cM interval between D11S1298 and D11S971 and most likely lies in a 3-cM region between GSTP1 and D11S1296. At present, no strong candidate genes colocalize with OPS.
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Cromosomas Humanos Par 11/genética , Neoplasias del Ojo/genética , Glioma/genética , Osteoporosis/genética , Alelos , Ceguera/complicaciones , Ceguera/congénito , Ceguera/genética , Niño , Mapeo Cromosómico , Consanguinidad , ADN/genética , Neoplasias del Ojo/complicaciones , Femenino , Genes Recesivos , Ligamiento Genético , Marcadores Genéticos , Glioma/complicaciones , Humanos , Recién Nacido , Masculino , Osteoporosis/complicaciones , Linaje , SíndromeRESUMEN
Nuclear magnetic resonance (NMR) and magnetic resonance imaging (MRI) have been applied to visualize physiological phenomena in plants and agricultural crops. Imaging sequences that result in contrast of a combination of parameters (e.g., proton density, T1, T2, T2*) cannot be used for a correct and unique interpretation of the results. In this study multiecho imaging together with monoexponential T2 decay fitting was applied to determine reliable proton density and T2 distributions over a mushroom. This was done at three magnetic field strengths (9.4, 4.7, and 0.47 T) because susceptibility inhomogeneities were suspected to influence the T2 relaxation times negatively, and because the influences of susceptibility inhomogeneities increase with a rise in magnetic field strength. Electron microscopy was used to understand the different T2's for the various tissue types in mushrooms. Large influences of the tissue ultrastructure on the observed T2 relaxation times were found and explained. Based on the results, it is concluded that imaging mushrooms at low fields (around or below 0.47 T) and short echo times has strong advantages over its high-field counterpart, especially with respect to quantitative imaging of the water balance of mushrooms. These conclusions indicate general validity whenever NMR imaging contrast is influenced by susceptibility inhomogeneities.
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Agaricus , Espectroscopía de Resonancia Magnética/métodos , Agaricus/ultraestructura , Medios de Contraste , Gadolinio , Gadolinio DTPA , Compuestos Organometálicos , Ácido Pentético/análogos & derivadosRESUMEN
The effects of NH4+ on the intracellular pH (pHi) and on the ATP content in isolated perfused rat liver were studied by 31P n.m.r. spectroscopy. In the initial phase of perfusion an average pHi of 7.29 +/- 0.04 was estimated. The presence of low (0.5 mmol/l) and high (10 mmol/l) doses of NH4Cl induced significant intracellular acidification by -0.06 +/- 0.03 and -0.11 +/- 0.03 pH unit respectively. This effect was in contrast with the transient intracellular alkalinization observed in preliminary studies on isolated hepatocytes, which was caused by a passive entry of NH3 by non-ionic diffusion and subsequent conversion into NH4+. During application of 0.5 mmol/l NH4Cl the liver released 0.54 +/- 0.06 mumol of urea/min per g into the perfusate. When the intracellular availability of HCO3- was decreased by acetazolamide (0.5 mmol/l) or by removal of HCO3- from the perfusion medium, the decrease in pHi by NH4Cl application was significantly lower than under control conditions. Furthermore, synthesis of urea was significantly inhibited by the decrease in intracellular HCO3-. Under these conditions, 10 mmol/l NH4Cl caused the transient alkalinization that was expected because of the passive uptake of uncharged NH3. Therefore, it is concluded that the intracellular acidification induced by NH4Cl is caused by the continuous utilization of intracellular HCO3- via the synthesis of urea. This metabolic effect on pHi dominates the effects of passive NH3 entry. The rate of urea formation depends on continuous efflux of H+, which is strictly limiting the degree of intracellular acidification within a small range. If the extrusion of H+ by the Na+/H+ exchanger was inhibited by amiloride (0.5 mmol/l) during the NH4Cl application, the decrease in pHi was amplified and the formation of urea was significantly inhibited. The application of NH4Cl at 0.5 or 10 mmol/l decreased the ATP content by 11% or 22% respectively.
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Cloruro de Amonio/metabolismo , Hígado/metabolismo , Ácido 4,4'-Diisotiocianostilbeno-2,2'-Disulfónico , Ácido 4-Acetamido-4'-isotiocianatostilbeno-2,2'-disulfónico/análogos & derivados , Ácido 4-Acetamido-4'-isotiocianatostilbeno-2,2'-disulfónico/farmacología , Acetazolamida/farmacología , Adenosina Trifosfato/biosíntesis , Amilorida/farmacología , Animales , Ácido Carbónico/metabolismo , Proteínas Portadoras/efectos de los fármacos , Proteínas Portadoras/metabolismo , Concentración de Iones de Hidrógeno , Técnicas In Vitro , Hígado/efectos de los fármacos , Espectroscopía de Resonancia Magnética , Masculino , Perfusión , Ratas , Ratas Wistar , Intercambiadores de Sodio-Hidrógeno , Urea/metabolismoRESUMEN
The aim of this study was to investigate the effect of NH4+ on the intracellular pH in TALH SVE.1 cells derived from the medullary thick ascending limb of Henle's loop (TALH) of rabbit kidney. These cells are specialized to perform NH4+ transport in vivo. Intracellular pH was monitored by 31P-NMR. The steady state intracellular pH (pHi) under standard conditions was 7.24 +/- 0.04 (n = 46). Exposure to NH4Cl resulted in an initial intracellular acidification of the TALH SVE.1 cells, followed by a recovery to the initial steady-state pHi value. The NH4(+)-induced acidification followed saturation kinetics up to 20 mM NH4Cl (delta pHmax = 0.2 pHunits). Half-maximal acidification was observed at 0.6 mmol/l. The intracellular acidification due to NH4Cl exposure was completely inhibited by 0.1 mM of the diuretic bumetanide, an inhibitor of the Na+/K+/2Cl- cotransporter. The effect of bumetanide was dose-dependent and a Ki value of 8.10(-7) M was calculated. NH4+ influx via K+ channels or the (Na+ + K+)ATPase could not be detected. pHi recovery to the initial value was caused mainly by amiloride-sensitive Na+/H+ exchange and to a lesser extent by an amiloride-insensitive system, which was not studied in detail. In the presence of bumetanide, pulses of high concentrations of NH4Cl induced small intracellular alkalinizations. From these experiments, an intrinsic buffer capacity (beta i) in TALH SVE.1 cells of 26 +/- 3 mM x pH-1 (pHi = 7.65) was determined. It could also be shown that the TALH SVE.1 cells exhibit maximal 'functional buffer capability' between pHout 6.9 and 7.3. Within these limits the cells can maintain their intracellular pH at a constant level, even though the extracellular pH changes. These data strongly suggest that the Na+/K+/2Cl- cotransporter is the main site of NH4+ entry into rabbit thick ascending limb cells in culture. A high intracellular buffer capacity and potent acid extrusion mechanism cooperate in counteracting the intracellular acidification caused by NH4+ influx into the cell.
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Cloruro de Amonio/farmacología , Riñón/metabolismo , Amilorida/farmacología , Amoníaco/metabolismo , Animales , Transporte Biológico , Tampones (Química) , Línea Celular , Permeabilidad de la Membrana Celular , Cloruros/metabolismo , Concentración de Iones de Hidrógeno , Riñón/citología , Riñón/efectos de los fármacos , Cinética , Espectroscopía de Resonancia Magnética , Potasio/metabolismo , Conejos , Sodio/metabolismoRESUMEN
We report two sisters with mental retardation, coarse facial features, telecanthus, flat malar region, prominent lower lip, kyphoscoliosis, and tapering fingers. Although these patients' phenotypes showed considerable overlap with the Coffin-Lowry and the Atkin-Flaitz syndromes, their overall picture makes these diagnoses controversial.
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Anomalías Múltiples/genética , Huesos Faciales/anomalías , Dedos/anomalías , Discapacidad Intelectual/genética , Fenotipo , Aberraciones Cromosómicas Sexuales/genética , Cromosoma X , Anomalías Múltiples/diagnóstico , Adolescente , Diagnóstico Diferencial , Femenino , Genes Dominantes/genética , Humanos , Discapacidad Intelectual/diagnóstico , SíndromeRESUMEN
Recently a new family of membrane proteins comprising the bovine lens fibre major intrinsic protein, soybean nodulin-26 protein and the Escherichia coli glycerol facilitator has been described [M.E. Baker and M.H. Saier, Jr (1990) Cell, 60, 185-186]. These proteins have six putative membrane spanning domains and one (probably intracellular) intermembrane fragment is particularly well conserved. We have identified a new member of this family in the yeast Saccharomyces cerevisiae. It also possesses the six transmembrane domains and the highly conserved intermembrane sequence. In contrast to the other three proteins which are all approximately 280 amino acids long, the yeast protein has an N-terminal extension of approximately 250 amino acids, which contains a string of 17 asparagine residues and a C-terminal extension of approximately 150 amino acids. The gene, which we called FPS1 (for fdp1 suppressor), suppresses in single copy the growth defect on fermentable sugars of the yeast fdp1 mutant but it is not allelic to FDP1. The deficiency of the fdp1 mutant in glucose-induced RAS-mediated cAMP signalling and in rapid glucose-induced changes in the activity of certain enzymes was not restored. Deletion of FPS1 does not cause any of the phenotypic deficiencies of the fdp1 mutant.
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AMP Cíclico/metabolismo , Proteínas del Ojo/genética , Genes Fúngicos , Glicoproteínas de Membrana/genética , Familia de Multigenes , Saccharomyces cerevisiae/genética , Secuencia de Aminoácidos , Animales , Acuaporinas , Secuencia de Bases , Metabolismo de los Hidratos de Carbono , Bovinos , ADN de Hongos/genética , Escherichia coli/metabolismo , Fermentación , Genes Supresores , Genes ras , Espectroscopía de Resonancia Magnética , Datos de Secuencia Molecular , Mutación , Mapeo Nucleótido , Mapeo Restrictivo , Transducción de SeñalRESUMEN
Addition of glucose or related fermentable sugars to derepressed cells of the yeast Saccharomyces cerevisiae triggers a RAS-protein-mediated cAMP signal, which induces a protein phosphorylation cascade. Yeast strains without a functional CDC25 gene were deficient in basal cAMP synthesis and in the glucose-induced cAMP signal. Addition of dinitrophenol, which in wild-type strains strongly stimulates in vivo cAMP synthesis by lowering intracellular pH, did not enhance the cAMP level. cdc25 disruption mutants, in which the basal cAMP level was restored by the RAS2val19 oncogene or by disruption of the gene (PDE2) coding for the high-affinity phosphodiesterase, were still deficient in the glucose- and acidification-induced cAMP responses. These results indicate that the CDC25 gene product is required not only for basal cAMP synthesis in yeast but also for specific activation of cAMP synthesis by the signal transmission pathway leading from glucose to adenyl cyclase. They also show that intracellular acidification stimulates the pathway at or upstream of the CDC25 protein. When shifted to the restrictive temperature, cells with the temperature sensitive cdc25-5 mutation lost their cAMP content within a few minutes. After prolonged incubation at the restrictive temperature, cells with this mutation, and also those with the temperature sensitive cdc25-1 mutation, arrested at the 'start' point (in G1) of the cell cycle, and subsequently accumulated in the resting state G0. In contrast with cdc25-5 cells, however, the cAMP level did not decrease and normal glucose- and acidification-induced cAMP responses were observed when cdc25-1 cells were shifted to the restrictive temperature.(ABSTRACT TRUNCATED AT 250 WORDS)
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Proteínas de Ciclo Celular , AMP Cíclico/metabolismo , Proteínas Fúngicas/metabolismo , Glucosa/metabolismo , Saccharomyces cerevisiae/metabolismo , Transducción de Señal , Proteínas ras , ras-GRF1 , Adenosina Trifosfato , Adenilil Ciclasas/metabolismo , AMP Cíclico/biosíntesis , Concentración de Iones de Hidrógeno , Mutación , Saccharomyces cerevisiae/genética , Saccharomyces cerevisiae/crecimiento & desarrollo , Proteínas de Saccharomyces cerevisiae , TemperaturaRESUMEN
NMR spectroscopy has been used to characterize a new renal cell line, TALH-SVE.1, which is derived from the medullary thick ascending limb of Henle's loop. From the 31P-NMR spectrum of a suspension of TALH-SVE cells using the chemical shift of the intracellular inorganic phosphate a value of 7.24 +/- 0.04 for the steady-state intracellular pH (pHi) was determined at pHo = 7.40. In addition, the 31P-NMR spectrum indicated rather high levels of UDPG, a finding confirmed by 1H-NMR spectra of perchloric acid extracts. The 1H-NMR data also demonstrate the presence of 'organic osmolytes' such as inositol, sorbitol, choline and glycerophosphoryl choline (GPC). 13C-NMR spectra of perchloric acid extracts of TALH-SVE cells incubated with [2-13C]- and [3-13 C]alanine were used to determine the relative influx in the Krebs cycle via pyruvate carboxylase (PCB) versus the influx via pyruvate dehydrogenase (PDH). The ratio was 0.41, while about 52% of all acetyl-CoA entering the Krebs cycle was unlabeled. 13C-NMR experiments also indicated that TALH-SVE cells lack gluconeogenic activity. The NMR study presented indicates that TALH-SVE cells possess metabolic pathways similar to those of the parental cells.
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Ciclo del Ácido Cítrico , Médula Renal/química , Asa de la Nefrona/química , Alanina/farmacología , Animales , Línea Celular/química , Epitelio/química , Concentración de Iones de Hidrógeno , Asa de la Nefrona/enzimología , Asa de la Nefrona/metabolismo , Espectroscopía de Resonancia Magnética , Modelos Biológicos , Percloratos , Fosfatos , Piruvato Carboxilasa/metabolismo , Complejo Piruvato Deshidrogenasa/metabolismo , Conejos , Uridina Difosfato Glucosa/metabolismoRESUMEN
[2-13C]Succinate has been used to examine the metabolic carbon flux from the Krebs cycle in rat renal proximal convoluted tubular (PCT) cells under physiological and pathophysiological conditions. Therefore, we developed a mathematical model that enabled us to determine the metabolic fluxes of the Krebs cycle. A mathematical model for the calculation of flux from [2-13C]succinate was used to determine fluxes in rat PCT cells during chronic acidosis in the presence and absence of 0.1 mM angiotensin II. The relative carbon efflux via glutamate dehydrogenase in rat renal PCT cells increases during chronic acidosis from 0.27 to 0.39, whereas this carbon flux is not affected by the presence of peptide hormone angiotensin II in the incubation medium. The fraction of intermediate 13C-labelled oxaloacetate transformed into the phosphoenolpyruvate and aspartate pools increases significantly from 0.41 to 0.57 in the case of chronic acidosis. The carbon efflux is not affected by angiotensin II. The 13C-NMR data also show that the carbon efflux through phosphoenolpyruvate carboxykinase increases from 0.35 to 0.56 in rat renal PCT cells derived from chronic acidotic animals, as well as in the presence of angiotensin II. The present results indicate that angiotensin II affects only the flux through phosphoenolcarboxykinase, whereas chronic acidosis increases the flux through phosphoenolpyruvate carboxykinase as well as the gluconeogenic flux.
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Ciclo del Ácido Cítrico , Túbulos Renales Proximales/metabolismo , Succinatos/metabolismo , Animales , Isótopos de Carbono , Cinética , Espectroscopía de Resonancia Magnética/métodos , Modelos Teóricos , RatasRESUMEN
Addition of glucose or related fermentable sugars to derepressed cells of the yeast Saccharomyces cerevisiae triggers a RAS-mediated cyclic AMP (cAMP) signal that induces a protein phosphorylation cascade. In yeast mutants (tpk1w1, tpk2w1, and tpk3w1) containing reduced activity of cAMP-dependent protein kinase, fermentable sugars, as opposed to nonfermentable carbon sources, induced a permanent hyperaccumulation of cAMP. This finding confirms previous conclusions that fermentable sugars are specific stimulators of cAMP synthesis in yeast cells. Despite the huge cAMP levels present in these mutants, deletion of the gene (BCY1) coding for the regulatory subunit of cAMP-dependent protein kinase severely reduced hyperaccumulation of cAMP. Glucose-induced hyperaccumulation of cAMP was also observed in exponential-phase glucose-grown cells of the tpklw1 and tpk2w1 strains but not the tpk3w1 strain even though addition of glucose to glucose-repressed wild-type cells did not induce a cAMP signal. Investigation of mitochondrial respiration by in vivo 31P nuclear magnetic resonance spectroscopy showed the tpk1w1 and tpk2w1 strains, to be defective in glucose repression. These results are consistent with the idea that the signal transmission pathway from glucose to adenyl cyclase contains a glucose-repressible protein. They also show that a certain level of cAMP-dependent protein phosphorylation is required for glucose repression. Investigation of the glucose-induced cAMP signal and glucose-induced activation of trehalase in derepressed cells of strains containing only one of the wild-type TPK genes indicates that the transient nature of the cAMP signal is due to feedback inhibition by cAMP-dependent protein kinase.