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991.
An alternative method of determining the integrated input function, necessary in the quantitative [18F]fluorodeoxyglucose (FDG) autoradiographic model, has been developed. Using erythrocytes as reference tissue, researchers require only one blood sample after injection of FDG to obtain the integrated input function. METHODS: The amount of FDG-6-PO4 in the erythrocytes is proportional to their exposure to FDG, that is, the integrated input function. Free FDG is removed by washing the erythrocytes twice. Inter- and intraindividual differences of the metabolic rate of erythrocytes are corrected for by an in vitro incubation with a known amount of FDG. RESULTS: Validation of the proposed method was done by correlating the integrated input function, based on the glucose metabolism of the erythrocytes, to the integrated input function obtained by multiple venous blood samples. The new method provides the integrated input function with an accuracy better than +/-8%. CONCLUSION: By using erythrocytes as a reference tissue, researchers can determine the integrated input function in the quantitative FDG autoradiographic model with an accuracy sufficient for clinical PET studies. The simplicity of the method also makes it suitable for FDG studies on small children. With two samples, the method can also be used for a simplified graphical Patlak analysis. 相似文献
992.
993.
The catalytic portion of the chloroplast ATP synthase (CF1) is structurally asymmetric. Asymmetry of the otherwise symmetrical alpha3beta3 heterohexamer is induced by the presence of tightly bound nucleotides and interactions with the single-copy, smaller subunits. Lucifer Yellow vinyl sulfone (4-amino-N-[3-(vinylsulfonyl)phenyl]naphthalimide-3,6-disulfonic acid) rapidly and covalently binds to lysine 378 on one alpha subunit [Nalin, C. M., Snyder, B., and McCarty, R. E., (1985) Biochemistry 24, 2318-2324] [Shapiro, A. B. (1991) Ph.D. Thesis, Cornell University, Ithaca, NY). The asymmetrical binding of Lucifer Yellow to CF1 provides a method to investigate the cause of asymmetry in the alpha subunits. The reaction of CF1 with Lucifer Yellow was monitored by total fluorescence of bound Lucifer Yellow as well as by quantitative determination of Lucifer Yellow bound to the tryptic peptide that contains lysine 378 of the alpha subunit. The total binding of Lucifer Yellow to CF1 was not affected by the presence of tightly bound nucleotides or nucleotide in the medium. Neither the total binding of Lucifer Yellow to CF1 nor the reaction of alpha-lysine 378 with Lucifer Yellow was changed by the removal of the epsilon subunit, the delta subunit, or both subunits. The extent of incorporation of Lucifer Yellow into lysine 378 of the alpha subunit in (alphabeta)n was about three times that of Lucifer Yellow incorporation into CF1. Reconstitution of (alphabeta)n with gamma restored the binding of one Lucifer Yellow per alpha3beta3gamma. Therefore, the interactions between gamma and the alphabeta heterohexamer are important in conferring asymmetry to the alpha subunits of CF1. 相似文献
994.
We report the efficacy of oral clarithromycin and inhaled beclomethasone against severe bronchorrhea in a patient with alveolar cell carcinoma. A 54-year-old man produced about 500 to 900 ml of clear and egg-white-like sputum each day. Anti-cancer chemotherapy and erythromycin therapy did not reduce the volume of sputum. After administration of clarithromycin and inhaled beclomethasone, sputum volume decreased to about 300 nl each day and the patient's ability to perform daily activities improved. Two months later, clarithromycin was stopped and the patient was treated with inhaled beclomethasone alone. Sputum volume did not increase for 6 months, although the chestroentgenographic findings gradually worsened. Then the sputum volume gradually increased. Five months after the sputum volume began to increase, he was producing about 2 liters of sputum each day and died of respiratory failure. Although the levels of CA 19-9, SLX, and CEA in serum were all within the normal range, the sputum contained high levels of CA 19-9 (1,133,620 U/ml), SLX (3,000 U/ml), and CEA (283 ng/ml). In patients with bronchorrhea, measurement of tumor markers in sputum may be useful for the diagnosis of alveolar cell carcinoma. 相似文献
995.
We present a helical unwinding assay for reversibly binding DNA ligands that uses closed circular DNA, topoisomerase I (Topo I), and two-dimensional agarose gel electrophoresis. Serially diluted Topo I relaxation reactions at constant DNA/ligand ratio are performed, and the resulting apparent unwinding of the closed circular DNA is used to calculate both ligand unwinding angle (phi) and intrinsic association constant (Ka). Mathematical treatment of apparent unwinding is formally analogous to that of apparent extinction coefficient data for optical binding titrations. Extrapolation to infinite DNA concentration yields the true unwinding angle of a given ligand and its association constant under Topo I relaxation conditions. Thus this assay delivers simultaneous structural and thermodynamic information describing the ligand-DNA complex. The utility of this assay has been demonstrated by using calichearubicin B (CRB), a synthetic hybrid molecule containing the anthraquinone chromophore of (DA) and the carbohydrate domain of calicheamicin gamma1I. The unwinding angle for CRB calculated by this method is -5. 3 +/- 0.5 degrees. Its Ka value is 0.20 x 10(6) M-1. For comparison, the unwinding angles of ethidium bromide and DA have been independently calculated, and the results are in agreement with canonical values for these compounds. Although a stronger binder to selected sites, CRB is a less potent unwinder than its parent compound DA. The assay requires only small amounts of ligand and offers an attractive option for analysis of DNA binding by synthetic and natural compounds. 相似文献
996.
KM Schulte S Staudt D Niederacher M Finken-Eigen K K?hrer PE Goretzki HD R?her 《Canadian Metallurgical Quarterly》1998,30(9):549-554
Loss of heterozygosity (LOH) of the MTS1 (p16) tumor suppressor gene has been reported to occur frequently in thyroid cancer cell lines. In order to determine the frequency of LOH for these multiple tumor suppressor genes, we used microsatellite markers IFNA and D9S171 to perform differential quantitative polymerase chain reaction. Tumor DNA was isolated from native sections of tumor tissue. Control DNA was isolated from blood. PCR products were separated on 6% polyacrylamide sequencing gels and quantified according to peak height and area. Analysis was informative in 70% of cases for both markers, and in 88% for at least one out of both. LOH was found in 3 out of 35 informative patients (8.6%) with papillary thyroid cancer, in 1 out of 7 patients with follicular thyroid cancer (14.2%), and in 0 out of 18 medullary cancers (0%). No LOH was found in 11 informative patients with multinodular goitre, 7 with follicular adenoma, 4 with Graves' disease, and 6 with other thyroid disease. 75% of LOH was found in T1 and T2 stages, it was not more frequent in patients with lymphonodular metastasis. The low frequency of LOH in these types of thyroid cancer argues against a role of loss of heterozygosity at the MTS 1 and 2 gene locus in the development of differentiated thyroid neoplasia. 相似文献
997.
自从1998年引进Powerformer以来,ABB公司的研发工程师已经考虑制造基于相同基本原理的电动机。这种想法现在已变为现实,取各Mortorformer。这种新型电动机与Powerformer结合起来,使电力系统更简单,效率更高,成本更低,对环境的影响更小。 相似文献
998.
BACKGROUND AND METHOD: In a retrospective study 2,351 records from patients who underwent surgery for acute appendicitis during 1986-1993 were analysed. During this period, there were 362 patients with perforated appendicitis. The aim of this study was to analyse the complication rate, the period of antibiotic treatment and whether the complication rate decreased when intravenous treatment was followed by oral antibiotic treatment. RESULTS: The complication frequency was 18% which was significantly higher than that for non-perforated appendicitis of 10%. The complication rate was 15% in the group receiving additional oral antibiotics compared to 19% in the group receiving only intravenous antibiotics. This difference is not significant. CONCLUSION: Perforated appendicitis is however still associated with increased mortality and morbidity. 相似文献
999.
Karl R. Eriksson Brian W. Brooks John Glover 《Journal of chemical technology and biotechnology (Oxford, Oxfordshire : 1986)》1991,50(4):483-491
Gaseous mixtures of oxygen and toluene have been passed through a 50 Hz electrical discharge reactor at low pressure. Oxidation reactions produced benzaldehyde, benzene, benzyl alcohol and cresols. Reaction rates varied with partial pressure of reactants, electrical field strength and temperature, although, in the absence of an electrical discharge the thermal reaction was negligible. A fit to experimental data was obtained with an equation which included reactant concentrations, temperature and applied voltage. 相似文献
1000.