Single-day combined evaluation of regional myocardial perfusion and function at rest and peak exercise with 99mTc-MIBI in patients with coronary artery disease.

99mTc-labeled methoxy-isobutyl-isonitrile (MIBI) allows a simultaneous radionuclide assessment of regional heart function and perfusion. In this study the effectiveness of functional and perfusional images obtained with 99mTc-MIBI in the detection of coronary stenoses was compared with that of their combination. We studied 197 patients who underwent coronary angiography and a single-day radionuclide protocol including first pass angiography (multicrystal gamma camera) and single photon emission computed tomography, by means of 2 injections of 99mTc-MIBI at rest and at peak exercise. Fifteen patients had < 50% stenoses, 50 had 1-vessel, 69 2-vessel and 63 3-vessel disease, for a total of 377 pathological major coronary vessels; 129 patients had previous myocardial infarction. Functional images, perfusional tomograms and their combination showed the same sensitivity (98%) and specificity (80%) in detecting coronary patients. Regional sensitivity and specificity of the combined analysis achieved 87% and 82%, respectively, vs. 94% (p < 0.005) and 60% (p < 0.001) of functional images, and 88% (p = N.S.) and 74% (p < 0.05) of perfusional tomograms. Thus, the combined analysis of regional functional and perfusional abnormalities increased significantly the specificity in the detection of coronary stenoses, in comparison with the separate evaluation of function and perfusion, achieving also a slightly higher diagnostic accuracy (85%, vs. 81% and 83%, respectively). The results confirm that a single-day protocol simultaneously assessing regional myocardial function and perfusion with 99mTc-MIBI represents a rapid and effective diagnostic method, that allows the physician to assess the presence and functional importance of coronary stenoses in less than 4 hours.

Quantification and kinetics of 25-hydroxyvitamin D3 by isotope dilution liquid chromatography/thermospray mass spectrometry.

A liquid chromatography/thermospray mass spectrometry method has been developed and used to measure the plasma levels and half-life of 25-hydroxyvitamin D3 in adults. The mean plasma levels of 25-hydroxyvitamin D3 averaged 40 ng ml-1 (n = 4) in summer and 30 ng ml-1 (n = 6) in winter. The method was also used to determine the half-life of serum 25-hydroxyvitamin D3 in subjects maintained on either high or low-fiber diets who had been given an intravenous infusion of (6,19,19-2H3)25-hydroxyvitamin D3 sufficient to label 5% of their estimated body pools. The half-life was determined to be 10.4 days (n = 4), which is approximately 50% of the currently accepted value of 19 days, determined using radiolabeled methods. This difference may be due to kinetic isotope effects arising as a result of the tritiated compounds being labeled at sites that undergo Cyt-P450-catalyzed oxidations.

Synthesis of 25-hydroxy-[6,19,19'-2H3]vitamin D3 and 1 alpha,25-dihydroxy-[6,19,19'-2H3]vitamin D3.

Synthesis of polydeuterated analogs of 25-hydroxyvitamin D3 and 1 alpha,25-dihydroxy vitamin D3 are described. These analogs, containing stable isotope atoms at metabolically stable positions, are potentially useful in studies involving catabolism of hydroxylated metabolites of vitamin D3.

Free mobility determination by electrophoresis in polyacrylamide containing agarose at a nonrestrictive concentration.

In the determination of the free mobility, related to the surface net charge, by quantitative gel electrophoresis, the previous arbitrary extrapolation of Ferguson plots from the lowest gel concentrations that give a mechanically stable gel to 0% T has recently been replaced by measurement of mobilities across that concentration range, using the addition of 0.5% agarose to polyacrylamide at the various low concentrations in application to a DNA fragment 155 bp in size (Orbán, L. et al., in preparation). The present study applies that approach to several proteins and DNA fragments smaller than 1300 bp, using 0.4% agarose in polyacrylamide gels of varying concentration. The intercepts of the plots with the mobility axis provide experimental data by which the free mobility in polyacrylamide gel electrophoresis can be estimated for molecules not significantly retarded in their migration at the agarose concentration admixed to polyacrylamide. Across the gel concentration range below 3% T, in the presence of agarose, the Ferguson plots of proteins and DNA fragments are convex. It was shown by mass spectrometry that this convex curvature of the plots in the mixed polymer is not significantly due to low polymerization efficiency in the concentration range of liquid polyacrylamide (below 3%T).

[Improvement in the accuracy of diagnosis of ischemic heart disease with simultaneous radioisotope evaluation of regional myocardial function perfusion and an exercise test]. / Incremento di accuratezza nella diagnosi di cardiopatia ischemica mediante valutazione radioisotopica simultanea della funzione e della perfusione miocardica regionali ed unico test ergometrico.

The recently developed myocardial agent methoxy-isobutyl-isonitrile (MIBI), labelled to 99mTc, allows one to evaluate global and regional ventricular function as well as myocardial perfusion by means of a single exercise stress test, significantly increasing diagnostic accuracy for coronary artery disease. Between September 1988 and March 1989, 407 patients with either suspected or already ascertained coronary artery disease underwent simultaneous assessment of regional ventricular function with first pass radionuclide angiography, and of myocardial perfusion with single photon emission computerized tomography, by means of 2 injections of 99mTc-MIBI at rest and at peak of the same exercise test. Out of these patients, 56 (52 men and 4 women, whose mean age was 57 +/- 7 years) underwent coronary angiography within 6 months of radionuclide examination and were included in the study. There were 13 1-vessel, 26 2-vessel and 17 3-vessel disease patients. Thirty-six of them had had a previous (greater than 6 months old) myocardial infarction, on the anterior wall in 16 patients, on the inferior wall in 20. In all patients a computerized bicycle stress test was performed; interruption criteria were ST segment depression greater than or equal to 1 mm in 27 patients (48%), the achievement of a heart rate greater than 85% of maximal age-predicted heart rate in 12 patients (22%) and fatigue in 17 patients (30%). Scintigraphic results were compared to angiographic findings: global sensitivity and specificity of the simultaneous evaluation were 82% and 81%, respectively, vs 95% and 56% of functional results and 85% and 71% of perfusion results, respectively. Regional analysis was also performed, by dividing scintigraphic images into the territories supplied by the 3 main coronary vessels, i.e., left anterior descending artery (LAD), left circumflex artery (LCx) and posterior descending artery (PD). On LAD territory the simultaneous evaluation achieved a sensitivity of 88% and a specificity of 63%, vs 98% and 38% of functional analysis and 88% and 50% of perfusional analysis, respectively. On LCx territory sensitivity and specificity were respectively 71% and 96%, vs 91% and 64% of function, and 77% and 96% of perfusion alone. On PD territory sensitivity was 85%, vs 94% and 91%, respectively; specificity was 73%, vs 55% and 55%, respectively. Combined functional and perfusional analysis achieved a 68% sensitivity in identifying less than or equal to 75% coronary narrowings, and a 90% sensitivity for greater than 90% narrowings.(ABSTRACT TRUNCATED AT 400 WORDS)

Metabolic conversion of 2-propylpentanal acetals to valproic acid in vitro. Model prodrugs of carboxylic acid agents.

As part of an investigation to test the feasibility of using acetals as precursors of acidic drugs, the dimethyl, diethyl, [2H10]diethyl, and diisopropyl acetals of 2-propylpentanal were synthesized and their metabolic conversion to the anticonvulsant, valproic acid (2-propylpentanoic acid), was investigated. The acetals were incubated with either 10,000g supernatant or microsomes isolated from rat liver. Data from the measurement of the metabolite, valproic acid, with selected ion monitoring gas chromatography/mass spectrometry indicated that the dimethyl, diethyl, [2H10]diethyl, and diisopropyl acetals were substrates. The amount of valproic acid produced from the incubation of 2-propylpentanal diethyl acetal with 10,000g supernatant was reduced by the cytochrome P-450 inhibitor, SKF-525A. The production of acid was also decreased by lack of NADPH or oxygen. These data are consistent with a cytochrome P-450 mediated reaction. 2-Propyl-1-pentanol was the major metabolite identified from microsomal preparations free of soluble fraction enzymes. A deuterium isotope effect calculated as the ratio of the amount of valproic acid produced from unlabeled and [2H5]ethyl-labeled substrate was 1.2. Failure to detect an ester as a metabolite of 3-phenylpropanal diethyl acetal along with the results of the isotope effect studies suggest that the mechanistic pathway of acyclic acetal metabolism involves oxidation of an ether methylene and not oxidation at the acetal carbon.

[Effects of slow-release isosorbide-5-mononitrate on ergometric parameters and cardiac output in stable effort angina pectoris: a double-blind randomized placebo study]. / Effetti dell'isosorbide-5-mononitrato in formulazione retard sui parametri ergometrici e sulla portata cardiaca nell'angina da sforzo stabile: studio in doppio cieco, randomizzato con placebo.

The effects of a single oral dose of 60 mg of sustained release (R) isosorbide-5-mononitrate (ISM) administered in 9 male patients (mean age: 53 +/- 7 years) with stable exercise-induced angina pectoris were studied in a randomized, double blind, cross-over study. The effectiveness of the drug was evaluated by concomitant ergometer exercise stress test and cardiac output determination (bioimpedance method, Bomed Med-Ltd) performed 1 hour before and 1, 4, 10 and 24 hours after acute administration of placebo (P) and ISM-R. After P, all patients showed a positive exercise test, whereas 3 patients during ISM-R treatment had a negative exercise stress test 1 and 4 hours after ISM-R administration. Compared with P, ISM-R produced a statistically significant improvement of exercise stress test parameters at peak exercise (maximum work load, heart rate, systolic and diastolic blood pressures and double product) up to 10 hours after drug administration. On the other hand, cardiac output did not significantly differ at any time after ISM-R compared with both control conditions and P treatment. Moreover, no side effect was detected in any patient during the study. In conclusion, a single oral dose of 60 mg of sustained-release ISM-R seems to be an effective drug in the treatment of effort angina, its effectiveness lasting more than 10 hours without side effects.

The adsorption of large proteins in electrofocusing on immobilized pH gradients: II. Dependence on the oligomeric state of Immobiline.

Five proteins with molecular mass in excess of 200 kDa were found to adsorb onto gels during isoelectric focusing on immobilized pH gradients (IPGEF). To probe for the mechanism of that adsorption, the homogeneity of the six Immobiline preparations used to make IPGEF gels was tested. Five of these Immobiline preparations appear homogeneous in gel filtration of Sephadex G-10. The sixth Immobiline (pK 9.3) exhibits a minor component eluting ahead of the major peak and comprising less than 4% of the total Immobiline absorbing at 226 nm. The proportion of the minor component increases with column load. Major and minor components when isolated appear to equilibrate with one another. Judging by the results of mass spectrometry, all 6 preparations are free of small aggregates of less than 500-600 Da molecular mass. Ultrafiltration of the Immobiline preparations through a membrane with 500 Da nominal cutoff leads to partial desorption of only 3 of the 5 adsorbed proteins. CHAPS is ineffectual in desorbing the 5 proteins from the IPG gel made with ultrafiltered Immobilines. None of the 6 Immobiline preparations used precipitates ferritin. All large proteins that adsorb onto IPGEF gels in the pH range 4-9.5 also adsorb onto commercial IPGEF gels in the pH range 4-7.