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2.
Phys Rev Lett ; 103(4): 045001, 2009 Jul 24.
Artículo en Inglés | MEDLINE | ID: mdl-19659361

RESUMEN

We have observed a bursting mode in the high-beta plasmas above the ideal beta limit without a conducting wall. The mode frequency is chirping down as the mode amplitude increases, and its initial value is close to the precession frequency of the trapped energetic particle from the perpendicular neutral beams. The mode structure is radially extended with a peak around the q = 2 surface. This mode can finally trigger the resistive wall mode (RWM) despite enough plasma rotation for RWM stabilization. It is concluded that the mode is driven by trapped energetic particles. The mode is attributed to the interaction between the trapped energetic particles and a marginally stable mode in the wall-stabilized high-beta_{N} region.

3.
Phys Rev Lett ; 98(5): 055002, 2007 Feb 02.
Artículo en Inglés | MEDLINE | ID: mdl-17358869

RESUMEN

The plasma rotation necessary for stabilization of resistive-wall modes (RWMs) is investigated by controlling the toroidal plasma rotation with external momentum input by injection of tangential neutral beams. The observed threshold is 0.3% of the Alfvén velocity and much smaller than the previous experimental results obtained with magnetic braking. This low critical rotation has a very weak beta dependence as the ideal wall limit is approached. These results indicate that for large plasmas such as in future fusion reactors with low rotation, the requirement of the additional feedback control system for stabilizing RWM is much reduced.

4.
Phys Rev Lett ; 92(3): 035001, 2004 Jan 23.
Artículo en Inglés | MEDLINE | ID: mdl-14753880

RESUMEN

A new operational scenario of advanced tokamak formation was demonstrated in the JT-60U tokamak. This was accomplished by electron cyclotron and lower hybrid waves, neutral beam injection, and the loop voltage supplied by the vertical field and shaping coils. The Ohmic heating (OH) solenoid was not used but a small inboard coil (part of the shaping coil), providing less than 20% of total poloidal flux, was used. The plasma thus obtained had both internal and edge transport barriers, with an energy confinement time of 1.6 times H-mode scaling, a poloidal beta of 3.6, and a normalized beta of 1.6, and a large bootstrap current fraction (>90%). This result opens up a possibility to reduce, and eventually eliminate, the OH solenoid from a tokamak reactor, which will greatly improve its economic competitiveness.

5.
Opt Lett ; 28(15): 1293-5, 2003 Aug 01.
Artículo en Inglés | MEDLINE | ID: mdl-12906067

RESUMEN

In previous work on polarization-mode dispersion (PMD) measurement with an optical time-domain reflectometer with polarimetry (p-OTDR), scatterers were assumed to be a cloud of small spherical particles in a fiber. We have found that the p-OTDR waveforms were fitted well by modified Mueller matrices, assuming scattering by a cloud of nonspherical particles. We realized a PMD measurement based on the p-OTDR Jones matrix eigenanalysis (JME) method. The measured PMD was consistent with that of JME standard measurement with transmission-type polarimetry.

6.
Inorg Chem ; 40(8): 1816-9, 2001 Apr 09.
Artículo en Inglés | MEDLINE | ID: mdl-11312736

RESUMEN

Two new vanadoselenites, [SeV(3)O(11)](3)(-) and [Se(2)V(2)O(10)](2)(-), were synthesized by reacting SeO(2) with VO(3)(-). Single-crystal X-ray structural analyses of [(n-C(4)H(9))(4)N](3)[SeV(3)O(11)].0.5H(2)O [orthorhombic, space group P2(1)2(1)2, a = 22.328(5) A, b = 44.099(9) A, c = 12.287(3) A, Z = 8] and [[(C(6)H(5))(3)P](2)N](2)[Se(2)V(2)O(10)] [monoclinic, space group P2(1)/n, a = 12.2931(3) A, b = 13.5101(3) A, c = 20.9793(5) A, beta = 106.307(1) degrees, Z = 2] revealed that both anions are composed of Se(x)()V(4)(-)(x)()O(4) rings. The (51)V, (77)Se, and (17)O NMR spectra established that both [SeV(3)O(11)](3)(-) and [Se(2)V(2)O(10)](2)(-) anions maintain this ring structure in solution.

7.
Biochem J ; 355(Pt 2): 537-44, 2001 Apr 15.
Artículo en Inglés | MEDLINE | ID: mdl-11284743

RESUMEN

Human dihydrodiol dehydrogenase (DD) 4/aldo-keto reductase (AKR) 1C4 is a major isoform of hepatic DD that oxidizes trans-dihydrodiols of polycyclic aromatic hydrocarbons to reactive and redox-active o-quinones and that reduces several ketone-containing drugs. To investigate the mechanism of transcriptional regulation of the human DD4 gene, the 5'-flanking region of the gene was fused to the luciferase gene. The results of luciferase assays using HepG2 cells and of 1,10-phenanthroline-copper footprinting indicated that two positive regulatory regions were located in regions from -701 to -684 and from -682 to -666. The former region contained a putative hepatocyte nuclear factor (HNF)-4 binding motif, and the latter region contained an HNF-1 consensus binding sequence. DNA fragments of the HNF-4 or HNF-1 motif gave a shifted band in a gel-shift assay with nuclear extracts from HepG2 cells. The formation of the DNA-protein complex was inhibited by the HNF-4 or HNF-1 motif of the alpha(1)-antitrypsin gene. A supershift assay using antibodies to human HNF-4alpha, HNF-4gamma and HNF-1alpha showed that HNF-4alpha and HNF-4gamma bound to the HNF-4 motif, and that HNF-1alpha interacted with the HNF-1 motif. Introduction of mutations into the HNF-4 or HNF-1 motif lowered the luciferase activity to 10 or 8% respectively of that seen with the intact human DD4 gene. These results indicate that HNF-4alpha, HNF-4gamma and HNF-1alpha regulate co-operatively the transcription of the human DD4 gene in HepG2 cells.


Asunto(s)
Oxidorreductasas de Alcohol/genética , Proteínas de Unión al ADN , Regulación Enzimológica de la Expresión Génica/fisiología , Proteínas Nucleares , Oxidorreductasas/genética , Fosfoproteínas/fisiología , Factores de Transcripción/fisiología , Transcripción Genética/fisiología , Aldehído Reductasa , Aldo-Ceto Reductasas , Secuencia de Bases , Factores de Transcripción Básicos con Cremalleras de Leucinas y Motivos Hélice-Asa-Hélice , Línea Celular , ADN , Huella de ADN , Factor Nuclear 1 del Hepatocito , Factor Nuclear 1-alfa del Hepatocito , Factor Nuclear 1-beta del Hepatocito , Factor Nuclear 4 del Hepatocito , Humanos , Datos de Secuencia Molecular , Mutación , Fenantrolinas/química , Fosfoproteínas/metabolismo , Regiones Promotoras Genéticas , Unión Proteica , Eliminación de Secuencia , Factores de Transcripción/metabolismo
8.
Arch Orthop Trauma Surg ; 121(3): 127-30, 2001.
Artículo en Inglés | MEDLINE | ID: mdl-11262775

RESUMEN

We studied the effects on the axial bone mass of total joint arthroplasty (TJA) for lower extremities in 48 female rheumatoid arthritis (RA) patients by using dual-energy X-ray absorptiometry (DXA). Twenty-nine postmenopausal RA patients treated only with nonsteroidal anti-inflammatory drugs (NSAIDs) served as controls. They were studied for an average duration of 63 months. The reduction in the bone mineral density (BMD) of the lumbar spine (L2-4) was significant in both groups (p < 0.01-0.05), but it was not statistically different between the two groups. The BMD of the femoral neck decreased significantly in both groups (p < 0.01-0.05) after 2 years, but it was not statistically different between the two groups. Our data suggest that TJA slowed the rapid axial bone loss usually associated with advanced RA.


Asunto(s)
Absorciometría de Fotón/métodos , Artritis Reumatoide/cirugía , Artroplastia de Reemplazo/métodos , Densidad Ósea/fisiología , Corticoesteroides/uso terapéutico , Anciano , Artritis Reumatoide/diagnóstico , Artritis Reumatoide/tratamiento farmacológico , Femenino , Estudios de Seguimiento , Humanos , Pierna , Persona de Mediana Edad , Periodo Posoperatorio , Probabilidad , Valores de Referencia , Índice de Severidad de la Enfermedad , Estadísticas no Paramétricas
9.
Opt Lett ; 26(17): 1314-6, 2001 Sep 01.
Artículo en Inglés | MEDLINE | ID: mdl-18049593

RESUMEN

We propose a novel technique for wideband tunable wavelength conversion of return-to-zero signals by optical time gating of a supercontinuum (SC) light source. A SC pulse generated by nonlinear propagation in a normal-dispersion fiber has a rectangular shape with highly linear upchirping. By control of the optical time-gating position, the center wavelength of time-gated SC pulse can be precisely tuned. Error-free 10-Gbit/s wavelength conversion with a tuning range of 27.1 nm is experimentally demonstrated.

10.
Anal Sci ; 17(1): 71-6, 2001 Jan.
Artículo en Inglés | MEDLINE | ID: mdl-11993680

RESUMEN

Fog and rain water samples were collected at the same time in the Akita Hachimantai mountain range in northern Japan from June to September in 1998 and 1999. The various ion concentrations in these samples were analyzed, and the fog droplet sizes were measured for each fog event. As the fog droplet size increased, the ion concentration decreased. The slope of log-log plots of the concentration versus the droplet size differed with the kind of ion. In order to characterize the air pollutant, moreover, these data were quantitatively analyzed by an oblique rotational factor analysis. We found that three factors were extracted as the air pollutant source: (NH4)2SO4, acids (HNO3 + H2SO4) and sea-salt. Combining the factor analysis with the 72 h back-trajectory at 850 hPa level, we found that the contribution of each factor varied with the transport pattern of air masses.


Asunto(s)
Lluvia Ácida/análisis , Contaminantes Atmosféricos/análisis , Análisis Factorial , Concentración de Iones de Hidrógeno , Lluvia , Tiempo (Meteorología)
11.
Int J Pharm ; 209(1-2): 69-77, 2000 Nov 19.
Artículo en Inglés | MEDLINE | ID: mdl-11084247

RESUMEN

Acid-treated yeast cell wall (AYC) was newly prepared by acidifying brewers' yeast cell wall. Core tablets containing 3% of acetaminophen (AAP) were coated with the AYC aqueous dispersion containing 5% (w/v) of AYC and 0.35% (w/v) of glycerol. The curing of AYC-coated tablets was performed at various curing periods of time and temperatures. The effects of curing on AAP release from AYC-coated tablets, the weight and thickness of the coated layer of AYC and the water sorption into the AYC-coated tablets were studied. The tensile strength and pore size distribution of the AYC cast film were measured. In the case of 60, 80, or 100 degrees C curing, AAP release from AYC-coated tablets showed a sigmoidal release profile with an initial lag time. The duration of the lag time increased with the increasing curing time and temperature, though the release rate after the lag time hardly changed. At 120 degrees C curing, the release rate after the lag time decreased with the increasing curing time and a sustained release was observed. The weight and thickness of the AYC-coated layer and the water sorption rate into AYC-coated tablets decreased with the increasing curing time and temperature. The tensile strength of the AYC cast film increased with increasing the curing temperature, particularly at 120 degrees C curing. It is considered that the water was evaporated from the AYC-coated layer and the adhesion force between AYC particles increased during curing, making the structure of the AYC-coated layer densely firm. The changes in the duration of lag time and the release rate may be due to changes in the structure of the AYC-coated layer caused by curing. These results show that it is feasible to control the lag time and the release rate of AAP from AYC-coated tablets by varying the curing time and temperature.


Asunto(s)
Pared Celular/química , Saccharomyces cerevisiae/química , Comprimidos Recubiertos/química , Acetaminofén/administración & dosificación , Acetaminofén/química , Ácidos , Analgésicos no Narcóticos/administración & dosificación , Analgésicos no Narcóticos/química , Composición de Medicamentos , Porosidad , Solubilidad , Temperatura , Resistencia a la Tracción , Factores de Tiempo , Agua/química
12.
Int J Pharm ; 204(1-2): 53-9, 2000 Aug 25.
Artículo en Inglés | MEDLINE | ID: mdl-11011986

RESUMEN

Acid-treated yeast cell wall (AYC) was newly prepared by acidifying the cell wall of brewer's yeast and the potential to use AYC as a novel coating material was studied. AYC had an oval shape with the diameter of several microm. The rheogram of AYC aqueous dispersion showed the plastic fluid property that is generally observed in the suspension. Core tablets containing 3% of acetaminophen (AAP) were coated with the AYC aqueous dispersion containing 5% (w/v) of AYC and 0.35% (w/v) of glycerol at various coating percents. The AAP release profile from the AYC-coated tablets was studied by the JP13 paddle method using solutions at various pH. Tensile strength and permeability of oxygen and water vapor of AYC cast film were measured. The AAP release from the AYC-coated tablets showed sigmoidal release profile with an initial lag time and the duration of the lag time depended on the coating percent of AYC. The pH of the dissolution fluid or the storage at room temperature for 120 days had little affect on AAP release from the AYC-coated tablets. These results suggest that it is possible to control the start time of medicine release independent of the pH by coating of AYC, that is the time-controlled release. The AYC cast film showed a large tensile strength and an extremely small oxygen permeability coefficient and a sufficient level of water permeability coefficient in order to protect from moisture. These results present that AYC has the high utility as a novel aqueous coating material for DDS preparations.


Asunto(s)
Acetaminofén/química , Analgésicos no Narcóticos/química , Glicerol/química , Saccharomyces cerevisiae/química , Pared Celular/química , Concentración de Iones de Hidrógeno , Excipientes Farmacéuticos , Comprimidos Recubiertos
13.
Joint Bone Spine ; 67(3): 188-93, 2000.
Artículo en Inglés | MEDLINE | ID: mdl-10875316

RESUMEN

OBJECTIVES: To examine the characteristic relationship between interleukin-16 (IL-16) and clinical data in various types of arthritis. METHODS: We measured IL-16 levels of the synovial fluids (SF) of patients with various types of arthritis, which included rheumatoid arthritis, traumatic arthritis, pseudogouty arthritis, gouty arthritis, and osteoarthritis, by an enzyme immunosorbent assay, and examined their correlations with clinical parameters. RESULTS AND CONCLUSIONS: Higher levels of IL-16 in synovial fluid from patients with rheumatoid arthritis, traumatic arthritis, and pseudogouty arthritis, compared to those with osteoarthritis, and gouty arthritis were indicated. Also, synovial IL-16 levels in patients with rheumatoid arthritis correlated significantly, especially with synovial matrix metalloproteinase-3 levels. But the IL-16 levels of both synovial fluid and peripheral blood did not correlate with conventional inflammatory parameters such as C-reactive protein, erythrocyte sedimentation rate, or rheumatoid factor. Although the function of IL-16 in inflammatory arthritis has not yet been defined, these data indicated some essential features of IL-16.


Asunto(s)
Artritis/inmunología , Artritis/metabolismo , Interleucina-16/metabolismo , Líquido Sinovial/inmunología , Líquido Sinovial/metabolismo , Adulto , Anciano , Anciano de 80 o más Años , Artritis/clasificación , Ensayo de Inmunoadsorción Enzimática , Femenino , Humanos , Masculino , Persona de Mediana Edad
14.
Int J Pharm ; 199(1): 77-83, 2000 Apr 10.
Artículo en Inglés | MEDLINE | ID: mdl-10794929

RESUMEN

We investigated the application of Carbopol(R) (CP) as a novel coating material prepared with various grades of CP having different degrees of cross-linking and molecular weights. Viscosity and spray mist size of CP aqueous solutions at various concentrations of CP were measured. Core tablets containing theophylline (TP), as a model drug, were coated with CP at various coating ratios. The TP release profile from the CP-coated tablets was studied by the JP13 paddle method. CP tablets were prepared by compressing CP powder, and the swelling behavior of the CP tablets in JP 1st fluid, purified water, and JP 2nd fluid was observed. The spray mist size of all CP aqueous solutions was small at a concentration of 1% and below, and drastically increased over a concentration of 1%. This result suggests that the appropriate concentration of the CP solution for coating is 1% or below. Sustained release of TP from the CP-coated tablets at a coating ratio of only 3% was observed in the JP 1st fluid and purified water, although fast release was observed in the JP 2nd fluid. The fast release in the latter fluid may be due to the fact that CP is an acid material. These results suggest that it is feasible to control the drug release by use of an extremely small amount of CP coating and that CP is useful as a novel coating material.


Asunto(s)
Polivinilos/química , Resinas Acrílicas , Broncodilatadores/química , Reactivos de Enlaces Cruzados , Portadores de Fármacos , Tamaño de la Partícula , Solubilidad , Comprimidos Recubiertos , Teofilina/química , Viscosidad
15.
Clin Rheumatol ; 19(1): 14-20, 2000.
Artículo en Inglés | MEDLINE | ID: mdl-10752493

RESUMEN

When synovial effusion is the only symptom, it is often difficult to make an exact diagnosis of the arthritic disease. To distinguish various types of arthritis with synovial effusion, we measured the levels of matrix metalloproteinase-3 (MMP-3, Stromelysin), tissue inhibitor of metalloproteinase-1 (TIMP-1) and rheumatoid factor (RF) isotypes in synovial fluid (SF) from patients with rheumatoid arthritis (RA), osteoarthritis (OA), pyogenic arthritis (PA), pseudogouty arthritis (PG), gouty arthritis (GA) and traumatic arthritis (TA). SF was aspirated from the knee joint or the ankle joint. Levels of IgG-, IgM- and IgA-RF isotypes were measured by ELISA. Levels of MMP-3 and TIMP-1 in SF were simultaneously determined by a one-step EIA system. Levels of IgG-RF, IgM-RF and MMP-3 in SF from RA patients were significantly higher than those in OA, PA, PG, GA and TA. However, IgA-RF in SF from RA patients, when compared with PA and GA, did not show a significantly increased level. In addition, TIMP-1 in SF from RA, when compared with PA and TA, also has not shown a significantly increased level. Therefore, in addition to analysing clinical data, measurements of IgG-RF, IgM-RF and MMP-3 in SF may contribute in distinguishing RA from other arthritic diseases.


Asunto(s)
Artritis/metabolismo , Isotipos de Inmunoglobulinas/metabolismo , Metaloproteinasa 3 de la Matriz/metabolismo , Factor Reumatoide/inmunología , Líquido Sinovial/metabolismo , Inhibidores Tisulares de Metaloproteinasas/metabolismo , Adolescente , Adulto , Anciano , Anciano de 80 o más Años , Artritis/diagnóstico , Biomarcadores , Niño , Preescolar , Diagnóstico Diferencial , Ensayo de Inmunoadsorción Enzimática , Femenino , Humanos , Masculino , Persona de Mediana Edad , Índice de Severidad de la Enfermedad
16.
Mech Ageing Dev ; 113(1): 23-35, 2000 Jan 24.
Artículo en Inglés | MEDLINE | ID: mdl-10708247

RESUMEN

The effects of long-term, light exercise under restricted feeding on age-related changes in physiological and metabolic functions were examined in male Wistar rats. Adult (100 days old) rats were divided into sedentary (R10S) and exercise (R11E) groups, and given 10 and 11 g/day, respectively, of a 20% casein diet until they reached 900 days of age. Group R11E simultaneously underwent 3000 m/day of running exercise throughout the test period. As compared with the sedentary group, long-term, light exercise significantly increased body nitrogen retention and serum protein levels, decreased body fat and plasma insulin levels, prevented age-related decline in the basal metabolic rate, and reduced age-associated histopathological changes in the kidney and liver. Long-term, light exercise further enhanced the benefits of restricted feeding on age-related deterioration in physiological and metabolic variables and improved body composition, but did not prolong survival at 900 days of age.


Asunto(s)
Envejecimiento/fisiología , Privación de Alimentos/fisiología , Esfuerzo Físico/fisiología , Envejecimiento/metabolismo , Envejecimiento/patología , Animales , Metabolismo Basal , Proteínas Sanguíneas/metabolismo , Composición Corporal , Riñón/patología , Hígado/patología , Longevidad/fisiología , Masculino , Nitrógeno/metabolismo , Tamaño de los Órganos , Ratas , Ratas Wistar , Carrera/fisiología
17.
J Control Release ; 63(3): 287-95, 2000 Feb 03.
Artículo en Inglés | MEDLINE | ID: mdl-10601724

RESUMEN

Solid dispersion composed of the poly(ethylene oxide) (PEO)-Carbopol((R)) (CP) interpolymer complex containing phenacetin (PHE) was prepared by using six grades of CP having various cross-linking degrees. We attempted to control the medicine release from the PEO-CP solid dispersion by varying the CP grade. The powder X-ray diffraction pattern and differential scanning calorimetry curves suggested that PHE existed in the amorphous state, and PEO in the crystalline state disappeared in the solid dispersions. The release profile of PHE varied depending on the CP grade. A small release rate was observed at CP910 and CP971P that are cross-linked at low and middle degrees, respectively. The Fourier transform-infrared (FT-IR) spectra showed that the amount of the PEO-CP complex formed by hydrogen bonding changed depending on the CP grade. With the cross-linked CP, a good correlation was observed between the hydrogen bonding percent and the percent released of the PHE after 60 min (D(60 min)), indicating that PHE release was controlled by the amount of PEO-CP complex formation in the solid dispersion. These results show that it is feasible to control the medicine release from PEO-CP solid dispersion by varying the CP grade.


Asunto(s)
Polietilenglicoles/administración & dosificación , Polivinilos/administración & dosificación , Resinas Acrílicas , Portadores de Fármacos , Fenacetina/administración & dosificación , Fenacetina/química , Polietilenglicoles/química , Polivinilos/química , Solubilidad
18.
Arch Orthop Trauma Surg ; 119(1-2): 18-21, 1999.
Artículo en Inglés | MEDLINE | ID: mdl-10076939

RESUMEN

We carried out a comparative study in 78 post-menopausal women with rheumatoid arthritis (RA). Forty-four women with a mean disease duration of 17.5 years had been treated with low-dose glucocorticoid (prednisone at < 5 mg/day) for at least 12 months. They were studied for an average period of 3 years and 8 months. The remaining 34 women had been treated only with nonsteroidal anti-rheumatic drugs (NSAIDs) and served as the control group. Bone mineral density (BMD) in the lumbar spine (L2-4) and femoral neck was measured by dual-energy X-ray absorptiometry (DXA). Reduction of BMD in the lumbar spine was significant in both groups (P < 0.05 to approximately 0.01), but there was no statistically significant difference between the two groups. BMD of the femoral neck decreased significantly (P < 0.05) in the prednisone group, but again the difference was not significant between the two groups. Our data suggest that low-dose prednisone administration probably does not induce significant axial bone loss in female RA patients.


Asunto(s)
Artritis Reumatoide/tratamiento farmacológico , Densidad Ósea/efectos de los fármacos , Glucocorticoides/uso terapéutico , Prednisona/uso terapéutico , Absorciometría de Fotón , Anciano , Análisis de Varianza , Antiinflamatorios no Esteroideos/uso terapéutico , Artritis Reumatoide/diagnóstico , Artritis Reumatoide/fisiopatología , Femenino , Estudios de Seguimiento , Humanos , Estudios Longitudinales , Persona de Mediana Edad , Posmenopausia , Valores de Referencia , Resultado del Tratamiento
19.
J Control Release ; 58(1): 87-95, 1999 Mar 08.
Artículo en Inglés | MEDLINE | ID: mdl-10021492

RESUMEN

Solid dispersion composed of the poly(ethylene oxide) (PEO)-carboxyvinylpolymer (CP) interpolymer complex containing phenacetin (PHE) was prepared by using nine grades of PEO having different molecular weights from 2000 to 4500000. We attempted to control the medicine release from the PEO-CP solid dispersion by varying the molecular weight of PEO. The physicochemical properties of the solid dispersion were analyzed by powder X-ray diffractometry and thermal analysis. The interaction between PEO and CP was analyzed by IR spectroscopy. Transmittance of the polymer solution was measured to study the complexation between PEO and CP. The release profile of PHE varied depending on the molecular weight of PEO. The minimum release rate was observed at the PEO molecular weight of 35000. It was found that the amount of the PEO-CP complex formation by hydrogen bonding changed depending on the molecular weight of PEO. These results indicate that it is feasible to control the medicine release from the PEO-CP solid dispersion by varying the molecular weight of PEO.


Asunto(s)
Polietilenglicoles/química , Analgésicos no Narcóticos/química , Rastreo Diferencial de Calorimetría , Portadores de Fármacos , Peso Molecular , Espectrofotometría Infrarroja , Difracción de Rayos X
20.
Comp Biochem Physiol B Biochem Mol Biol ; 124(3): 327-32, 1999 Nov.
Artículo en Inglés | MEDLINE | ID: mdl-10631808

RESUMEN

Phosphofructokinase (EC 2.7.1.11) is a major enzyme of the glycolytic pathway, catalyzing the conversion of fructose 6-phosphate to fructose 1,6-bisphosphate. In this study, we demonstrated the effect of ribose 1,5-bisphosphate on phosphofructokinase purified from rat kidney cortex. Ribose 1,5-bisphosphate relieved the phosphofructokinase from ATP inhibition and increased the affinity for fructose 6-phosphate at nanomolar concentrations. These activating effects of ribose 1,5-bisphosphate were enhanced in the presence of AMP. Ribose 1,5-bisphosphate reduced the inhibition of the phosphofructokinase induced by citrate. These results suggest that ribose 1,5-bisphosphate is an activator of rat kidney cortex phosphofructokinase and synergistically regulates the enzyme activity with AMP.


Asunto(s)
Corteza Renal/enzimología , Pentosafosfatos/metabolismo , Fosfofructoquinasa-1/metabolismo , Adenosina Monofosfato/metabolismo , Adenosina Monofosfato/farmacología , Adenosina Trifosfato/metabolismo , Animales , Ácido Cítrico/farmacología , Relación Dosis-Respuesta a Droga , Fructosadifosfatos/metabolismo , Fructosadifosfatos/farmacología , Fructosafosfatos/metabolismo , Pentosafosfatos/farmacología , Fosfofructoquinasa-1/efectos de los fármacos , Fosfofructoquinasa-1/aislamiento & purificación , Ratas
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