ABSTRACT
We present here a quantitative analysis of the ground state and magnetic properties of Ce3Pt23Si11, based on a crystalline electric field description within the mean-field approximation. In this face-centered cubic compound, the point group symmetry at the Ce site is orthorhombic. One main difficulty in this low symmetry case is that the CEF potential for Ce3+ ions is determined by five independent parameters, while only two magnetic excitations are observed by inelastic neutron scattering. Moreover the anisotropy of the magnetic susceptibility of the Ce ion, that permits an independent determination of the second-order CEF parameters is hidden by the cubic symmetry of the compound. A specific procedure is developed for this purpose that combines genetic algorithms and more conventional optimization methods. A set of CEF parameters is found that best reproduces the different experimental observations in both the paramagnetic and ferromagnetic phases of Ce3Pt23Si11. The analysis accounts for two seemingly contradictory properties: a strong local anisotropy that aligns the moment along a fourfold axis and a rather weak anisotropy of the bulk magnetization with an easy threefold magnetization axis. Ce3Pt23Si11 is shown to be a model system where single site anisotropies compete within a crystal structure of overall high symmetry.
Subject(s)
Asthma/diagnosis , Bronchial Provocation Tests/economics , Bronchoconstrictor Agents/pharmacology , Cost-Benefit Analysis , Methacholine Chloride/pharmacology , Adolescent , Adult , Asthma/economics , Asthma/immunology , Bronchial Provocation Tests/instrumentation , Bronchial Provocation Tests/methods , Bronchoconstrictor Agents/immunology , Female , Humans , Male , Methacholine Chloride/immunology , Middle AgedABSTRACT
No disponible
Subject(s)
Humans , Male , Female , Methacholine Chloride/adverse effects , Methacholine Chloride/analysis , Methacholine Chloride/economics , Asthma/drug therapy , Asthma/economics , Cost-Benefit Analysis/standards , Cost-Benefit Analysis , 50303 , Body Mass IndexABSTRACT
The current guidelines recommend an approach to asthma management based on asthma control, rather than asthma severity. Although several specific questionnaires have been developed and control criteria have been established based on clinical guidelines, the evaluation of asthma control is still not optimal. In general, these indicators provide adequate assessment of current control, but they are more limited when estimating future risk. There is much evidence demonstrating the persistence of airway inflammation and airway hyperresponsiveness (AHR) in patients with total control. Therefore, the objective of this review was to analyse the possible role of AHR monitoring as an instrument for assessing asthma control. We will evaluate its capacity as an indicator for future risk, both for estimating the possibility of clinical deterioration and loss of lung function or exacerbations. Furthermore, its relationship with inhaled corticosteroid treatment will be analysed, while emphasizing its capacity for predicting response and adjusting dosage, as well as information about the capability of AHR for monitoring treatment. Last of all, we will discuss the main limitations and emerging opportunities of AHR as an assessment instrument for asthma control.
Subject(s)
Asthma/physiopathology , Asthma/therapy , Monitoring, Physiologic/methods , Humans , Practice Guidelines as TopicABSTRACT
We explore the magnetic anisotropy of GaMnAs ferromagnetic semiconductor by Planar Hall Effect (PHE) measurements. Using low magnitude of applied magnetic field (i.e., when the magnitude H is smaller than both cubic Hc and uniaxial Hu anisotropy field), we have observed various shapes of applied magnetic field direction dependence of Planar Hall Resistance (PHR). In particular, in two regions of temperature. At T < Tc/2, the "square-shape" signal and at T > Tc/2 the "zigzag-shape" signal of PHR. They reflect different magnetic anisotropy and provide information about magnetization reversal process in GaMnAs ferromagnetic semiconductor. The theoretical model calculation of PHR based on the free energy density reproduces well the experimental data. We report also the temperature dependence of anisotropy constants and magnetization orientations. The transition of easy axis from biaxial to uniaxiale axes has been observed and confirmed by SQUID measurements.
Subject(s)
Metal Nanoparticles/chemistry , Models, Chemical , Semiconductors , Anisotropy , Computer Simulation , Magnetics , Materials Testing , TemperatureABSTRACT
Magnetic susceptibility anisotropy and high sensitivity magnetostriction measurements are used to investigate the symmetry of CeB(6) ordered states. The antiferromagnetic state is confirmed as tetragonal, but no deviation from the cubic symmetry is observed in the so-called antiferroquadrupolar phase, where only volume effects are detected. In this phase, the temperature dependence of the strain field susceptibilities is typical of nonordered quadrupoles. Moreover, while an antiferroquadrupolar order should be cubic, this symmetry is incompatible with the (½½½) ordering wave vector. The antiferroquadrupolar description of CeB(6) phase II is clearly inconsistent, and an alternative model, based on a unidimensional representation of the cube, has to be sought.
ABSTRACT
OBJECTIVE: To compare transfusion requirements and erythropoietic response in preterms between schedules of rEPO administration once or three times per week, using the same weekly dose. STUDY DESIGN: Prospective, randomized trial including infants weighing <1500 g at birth and/or were îº32 weeks' gestation: Group 1 (60 infants) received subcutaneous rEPO at 250 units kg(-1) per dose, three times weekly for 6 weeks; Group 2 (59 infants), at 750 units kg(-1) per dose, once weekly for 6 weeks. Efficacy was evaluated based on the transfusion requirement, hemoglobin changes, reticulocyte counts, serum transferrin receptor (sTfR) and serum ferritin. The frequency of adverse effects was registered in both groups. RESULT: A total of 13 infants were transfused in each group (relative risk: 0.98; 95% confidence interval: 0.4 to 2.3). Phlebotomy loss and red blood cell transfusion volumes received were similar in both groups. Hemoglobin levels were lower at end of study in Group 2 (10.6±1.5 g dl(-1) versus 11.5±1.4 g dl(-1); P<0.003). At end of study, reticulocyte counts and sTfR values increased and serum ferritin values decreased, without significant differences between the two groups. Incidence of complications was similar in both groups. CONCLUSION: The once-weekly rEPO schedule for very low birth weight infants proved as effective as the three-times-weekly schedule, in relation to erythropoietic stimulus and transfusion requirement.
Subject(s)
Anemia, Neonatal , Blood Transfusion/statistics & numerical data , Erythropoiesis/drug effects , Erythropoietin , Infant, Premature, Diseases , Anemia, Neonatal/metabolism , Anemia, Neonatal/physiopathology , Anemia, Neonatal/therapy , Drug Administration Schedule , Drug Monitoring , Erythropoietin/administration & dosage , Erythropoietin/adverse effects , Ferritins/blood , Hemoglobins/analysis , Humans , Infant, Newborn , Infant, Premature , Infant, Premature, Diseases/metabolism , Infant, Premature, Diseases/physiopathology , Infant, Premature, Diseases/therapy , Infant, Very Low Birth Weight , Injections, Subcutaneous , Receptors, Transferrin/blood , Recombinant Proteins , Reticulocyte Count , Thrombocytosis/etiology , Transfusion Reaction , Treatment OutcomeSubject(s)
Cat's Claw , HIV Protease Inhibitors , Herb-Drug Interactions , Plant Preparations , Atazanavir Sulfate , Cat's Claw/adverse effects , Female , HIV Protease Inhibitors/administration & dosage , HIV Protease Inhibitors/blood , HIV Protease Inhibitors/pharmacokinetics , HIV Protease Inhibitors/therapeutic use , Humans , Metabolic Clearance Rate , Middle Aged , Oligopeptides/administration & dosage , Oligopeptides/blood , Oligopeptides/pharmacokinetics , Oligopeptides/therapeutic use , Plant Preparations/administration & dosage , Plant Preparations/adverse effects , Pyridines/administration & dosage , Pyridines/blood , Pyridines/pharmacokinetics , Pyridines/therapeutic use , Ritonavir/administration & dosage , Ritonavir/blood , Ritonavir/pharmacokinetics , Ritonavir/therapeutic use , Saquinavir/administration & dosage , Saquinavir/blood , Saquinavir/pharmacokinetics , Saquinavir/therapeutic useABSTRACT
BACKGROUND: This study aimed to prove that the urinary trypsinogen-2 dip stick test can be used for early diagnosis of pancreatitis after endoscopic retrograde cholangiopancreatography (ERCP). METHODS: For this prospective, blinded, pilot study, urine samples were collected before ERCP, 1 h after ERCP, and 4 h after ERCP. The urine dipstick test was used to detect trypsinogen-2 on the basis of immunochromatography. The dipstick results were compared with those of current methods used to diagnose post-ERCP pancreatitis. Once the patient disposition was finalized, pancreatic enzymes, clinical findings, and final diagnosis were obtained from the chart and compared with the urine trypsinogen-2 test findings. The sensitivity, specificity, and positive and negative predictive values were calculated. RESULTS: The urine trypsinogen dip stick test was performed for 30 patients (15 men and 15 women). Post-ERCP pancreatitis was diagnosed in 5 of 29 patients by clinician assessment, serum pancreatic enzyme levels, or both. The amylase and lipase levels for post-ERCP patients with and without pancreatitis were 650 +/- 145 vs 134 +/- 26 (p = 0.023) and 1,658 +/- 594 vs 84 +/- 17 (p = 0.057), respectively. This statement proves that patients who developed post ERCP pancreatitis had significant elevation of amylase and lipase compared to patients who did not have pancreatitis. For the dip stick test, 6 of 28 patients had positive results in 1 h and 6 of 29 patients had positive results in 4 h. The sensitivity of the 1-h test was 1.0, and the specificity was 0.91. The positive predictive value (PPV) was 0.66, and the negative predictive value (NPV) was 1.0. The sensitivity of the 4-h test was 1.0, and the specificity was 0.96. The PPV was 0.8, and NPV value was 1.0. CONCLUSION: The urinary trypsinogen-2 dip stick test is useful for early diagnosis of post-ERCP pancreatitis and allows the testing physicians to begin management early in its course.
Subject(s)
Cholangiopancreatography, Endoscopic Retrograde/adverse effects , Pancreatitis/diagnosis , Trypsin/urine , Trypsinogen/urine , Acute Disease , Adolescent , Adult , Aged , Aged, 80 and over , Amylases/blood , Biomarkers/urine , Early Diagnosis , Female , Humans , Male , Middle Aged , Pancreatitis/etiology , Predictive Value of Tests , Reagent Strips , Sensitivity and SpecificityABSTRACT
La braquiterapia o radioterapia intersticial cerebral inicia con Leksell en 1951. Ha evolucionado con los aportes de Backlund y su amplio estudio del efecto del p32 en craneofaringiomas quísticos, complementándose esta modalidad terapéutica con radio-gamma-cirugía cuando el componente sólido de la lesión así lo ameritaba. La experiencia es transmitida a través de algunos de los autores (JFDC y RG) a Venezuela donde se continuó y donde se siguen aportando modificaciones, con la utilización de otro radioisótopo, el I131 y ampliando su aplicación a otros tipos de tumores quísticos como los de la región pineal
Subject(s)
Brachytherapy , Cerebrum , Phosphorus Radioisotopes , Radiosurgery , Radiotherapy , Medicine , VenezuelaABSTRACT
A simple and sensitive capillary electrophoresis method using UV detection has been developed for the direct determination of ranitidine (RANT) and famotidine (FAMT) in serum, urine and pharmaceutical formulations. A buffer consisting of 60 mM phosphate buffer adjusted to pH 6.5 was found to provide a very efficient and stable electrophoretic system for the analysis of both drugs. The detection limits obtained were 0.088 microgram ml(-1) for RANT and 0.16 microgram ml(-1) for FAMT.
Subject(s)
Famotidine/blood , Famotidine/urine , Ranitidine/blood , Ranitidine/urine , Chemistry, Pharmaceutical , Electrophoresis, Capillary/methods , Famotidine/chemistry , Ranitidine/chemistryABSTRACT
La incorporación de los inhibidores de la proteasa (saquinavir, ritonavir, indinavir, nelfinavir) en la terapia antirretroviral ha supuesto un importante descenso en la morbilidad y mortalidad provocada por el SIDA. Son compuestos no peptídicos que inhiben de forma potente y selectiva la proteasa del VIH-1. Se caracterizan por tener en común un metabolismo de eliminación hepático y una semivida de eliminación corta, con diferencias en el ámbito de absorción y distribución. Excepto el indinavir, deben administrarse con comidas. Poseen distintos perfiles de toxicidad, siendo el ritonavir el que presenta una mayor incidencia de reacciones adversas. La extensa metabolización por la isoenzima CYP3A4 del citocromo P450 puede originar interacciones de interés clínico. Actualmente, la carga viral y linfocitos T CD4 son los marcadores de evolución clínica de la enfermedad. Recientes estudios sugieren que la monitorización de las concentraciones plasmáticas pueden ser de utilidad en casos de no-adherencia, interacciones farmacocinéticas y fracaso virológico (AU)
Subject(s)
Humans , Antiviral Agents/therapeutic use , Antiviral Agents/pharmacokinetics , HIV Infections/drug therapy , HIV Infections/blood , Protease Inhibitors/therapeutic use , Protease Inhibitors/pharmacokinetics , Protease Inhibitors/adverse effectsABSTRACT
BACKGROUND: This procedure was done in order to evaluate the efficacy and safety of ethylcyanoacrylate as an adhesive for fixation of the bone flap. METHODS: One hundred consecutive craniotomies in patients older than 16 years in which the bone flap was fixed with ethyl-2-cyanoacrylate were studied. The osteosynthesis and any complications in all cases were followed clinically and radiologically for 3 months. RESULTS: Clinical and radiographic observation demonstrated that osteosynthesis was produced in 100% of the cases with no complications related to this procedure. CONCLUSION: This technique proved to be safe, fast, and easy to accomplish, with immediate stability of the bone flap and excellent cosmetic results.
Subject(s)
Adhesives , Bone Transplantation , Craniotomy , Cyanoacrylates , Adolescent , Adult , Aged , Child , Female , Follow-Up Studies , Humans , Male , Middle AgedABSTRACT
A cross-sectional study was designed to determine whether plasma concentrations of glutathione and cysteine in HIV-infected hemophiliacs vary according to the progression of the disease and to compare them with those obtained in HIV negative hemophiliacs. Cysteine, total glutathione and glutathione disulphide were measured in plasma of HIV-infected hemophiliacs at different stages of HIV infection and in plasma of HIV-negative hemophiliacs. CD4 and CD8 T-cell counts, leukocyte and lymphocyte counts, beta 2-microglobulin and p24 antigen values were recorded for HIV positive hemophiliacs at the time of the study. The hemophiliac HIV-positive group showed a decrease in total glutathione levels (-18%) and an increase of glutathione disulphide (8.18 vs. 14.90%) compared to the HIV-negative group. The cysteine levels found in HIV-positive hemophiliacs were not different from those found in the HIV-negative group. There were no differences with statistical significance in total glutathione, glutathione disulphide and cysteine among HIV-infected hemophiliacs according to the different clinical stage of the disease (AIDS vs. non-AIDS). The interest of evaluating plasma concentrations of glutathione and cysteine in HIV-infected patients is limited from the point of view of considering them as markers of progression of the disease. Interest in a therapeutic strategy designed to replenish or normalize glutathione plasma levels is also limited.
Subject(s)
Cysteine/blood , Glutathione/blood , HIV Seropositivity/blood , Hemophilia A/blood , Acquired Immunodeficiency Syndrome/blood , Adolescent , Adult , Disease Progression , Female , Glutathione/analogs & derivatives , Glutathione Disulfide , HIV Seropositivity/complications , Hemophilia A/complications , Humans , Male , Middle AgedABSTRACT
An isocratic reversed-phase high-performance liquid chromatographic method was developed to determine free didanosine concentrations in human serum. An ultrafiltration technique was used to recover didanosine from the samples. didanosine was analyzed using a 150 mm x 3.9 mm I.D. Nova-Pak phenyl column and a mobile phase of 0.02 M sodium citrate (pH 5)-isopropanol (97.5:2.5, v/v) with detection set at 250 nm. Linearity was verified from 25 to 3000 ng/ml. The limit of detection at a signal-to-noise ratio of 3 was 25 ng/ml. The mean recovery of didanosine added to serum at 50, 100, 250 and 750 ng/ml was 97.4%, 97.3%, 92.9% and 95.4%, respectively. A within-day variation of 3.6% at 50 ng/ml and 1.7% at 250 ng/ml, and a day-to-day variation of 9.3% at 50 ng/ml and 3.6% at 230 ng/ml were found. Stability studies indicated that didanosine is stable in serum for at least 8.5 months at 20 degrees C, 4 degrees C and -20 degrees C.
Subject(s)
Chromatography, High Pressure Liquid/methods , Didanosine/blood , Reverse Transcriptase Inhibitors/blood , Ultrafiltration/methods , Humans , Spectrophotometry, UltravioletABSTRACT
A rapid reversed-phase high-performance liquid chromatographic method with a 30-mm long column is described for assaying amphotericin B in serum. After deproteinization of serum samples with methanol, the supernatant was injected onto a reversed-phase C18 column, using 2.5 mM Na2EDTA-acetonitrile (70:30, v/v) as the mobile phase. Amphotericin B was eluted at 1.5 min. Calibration plot of the peak area against concentration was linear from 0.05 to 25 micrograms/ml (C.V. of 3%). Within-day and day-to-day imprecision (C.V.) ranged between 1.33% and 3.61%. The application was evaluated in 55 serum samples from patients treated with amphotericin B.