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Biomedical subjects

A Rabol

Publications and source records attributed to A Rabol.

9 recordsLinked to original sources
PubMed1997

Myocardial sestamibi single-photon emission tomography: variations in reference values with gender, age and rest versus stress?

Reference data files support the evaluation of myocardial perfusion single-photon emission tomography (SPET). The aim of this study was to create a large reference data base for technetium-99m sestamibi SPET, age and gender matched to the general patient population. One hundred and twenty-eight healthy volunteers (76 males and 52 females) with a likelihood of coronary artery disease of less than 5% underwent rest and maximal exercise 99mTc-sestamibi SPET with a 2-day protocol and 180 degrees elliptical rotation. The normalized activity values of 99mTc-sestamibi in the inferior wall differed significantly between men and women. Age variations were found for men in the anterior wall. Normalized activity values in all four walls were strikingly similar during rest and stress. Our results suggest that the use of reference files in 99mTc-sestamibi SPET requires a gender- and, for males, possibly an age-matched reference population. Different reference files at rest and during stress might not be necessary.

Adult↗
PubMed1997

The occurrence of false-positive technetium-99m sestamibi bull's eye defects in different reference databases. A study of an age- and gender-stratified healthy population.

Myocardial perfusion single-photon emission tomographic (SPET) imaging has been shown to be sensitive in the detection of coronary artery disease (CAD), whereas its specificity has been suboptimal. The aim of the present study was to study the frequency of abnormal bull's eye perfusion defects in a large age-stratified group of healthy subjects undergoing myocardial SPET assessed by comparison with two existing commercially available reference databases. One hundred and twenty-eight healthy volunteers (76 males and 52 females) with a less than 5% likelihood of CAD underwent rest and exercise technetium-99m sestamibi SPET. The false-positive response rate, defined as a significant reversible defect, was 12% when compared to the CEqual database and 29% when compared to the Cedars-Sinai database. With the CEqual program, rest defects occurred in 12% of the subjects. Defects occurred more often in women than in men, but the difference did not attain statistical significance. Significant defects were most frequent in the inferior wall and in women in the anterior wall as well. The distribution of defects was independent of age. Our results suggest that the specificity of 99mTc-sestamibi myocardial SPET using commercially available reference files is suboptimal. The risk of obtaining a false-positive test result in subjects undergoing 99mTc-sestamibi myocardial SPET with a very low likelihood of CAD was higher than anticipated. With both reference files false-positive test results were most frequently observed in the inferior wall. Our data suggest that commercial reference files for myocardial SPET need to be optimised, and should be used with caution. The use of attenuation correction may prove to be a major step forward.

Adult↗
PubMed1997

Restricted postexercise pulmonary diffusion capacity and central blood volume depletion.

Pulmonary diffusion capacity for carbon monoxide (DLCO), regional electrical impedance (Z0), and the distribution of technetium-99m-labeled erythrocytes together with concentration of plasma atrial natriuretic peptide (ANP) were determined before and after a 6-min "all-out" row in nine oarsmen and in six control subjects. Two and one-half hours after exercise in the upright seated position, DLCO was reduced by 6 (-2 to 21; median and range) %, the thoracic-to-thigh electrical impedance ratio (Z0 thorax/Z0 thigh) rose by 14 (-1 to 29) %, paralleled by a 7 (-3 to 11) % decrease and a 3 (-5 to 12) % increase in the thoracic and thigh blood volume, respectively. These responses were associated with a decrease in the plasma ANP concentration from 15 (13-31) to 12 (9-27) pmol/l (P < 0.05). Similarly, in the supine position, Z0 thorax/Z0 thigh increased by 10 (-5 to 28) % when DLCO was reduced 12 (6-26) % (P < 0.05), whereas DLCO remained stable in the control group. The increase in Z0 thorax/Z0 thigh and the corresponding redistribution of the blood volume in both body positions show that approximately one-half of the postexercise reduction of DLCO is explained by a decrease in the pulmonary blood volume. The role of a reduced postexercise central blood volume is underscored by the lower plasma ANP, which aids in upregulating the blood volume after exercise in athletes.

Adult↗
PubMed1996

Relationship between small-intestinal transit rate and intestinal absorption of (14)C-labelled mannitol and (51)Cr-labelled ethylenediaminetetraacetic acid in healthy subjects.

BACKGROUND: Although the small-intestinal transit rate is generally considered to influence the urinary excretion of markers of intestinal permeability, no study has until now formally addressed the importance of this influence in humans. METHODS: Ten healthy subjects ingested a test solution containing (99m)Tc-labelled diethylenetriaminepentaacetic acid ((99)mTc-DTPA), (14)C-labelled mannitol ((14)C-mannitol), and (51)Cr-labelled ethylenediaminetetraacetic acid ((51)Cr-EDTA). After ingestion, the small-intestinal transit rate of (99)mTc-DTPA was measured with the gamma camera technique. Urine was collected for time periods of 0-2 h, 2-4 h, and 4-6 h to measure the excretion of absorbed (14)C-mannitol and (51)Cr-EDTA. Moreover, the distribution volume and plasma clearance of (14)C-mannitol and (51)Cr-EDTA were determined in each subject. RESULTS: A positive correlation was found between mean small-intestinal transit time and 0- to 6-h urinary excretion of (14)C-mannitol. The study did not show any correlation between small-intestinal transit rate and 0- to 6-h urinary excretion of (51)Cr-EDTA. Urinary excretion of neither (14)C-mannitol nor (51)Cr-EDTA was affected by distribution volume or urine volume. A positive correlation was observed between plasma clearance and 0- to 6-h urinary excretion of (14)C-mannitol, whereas plasma clearance did not influence the urinary excretion of (51)Cr-EDTA. CONCLUSIONS: Small-intestinal transit rate seems to have a significant effect on 0- to 6-h urinary excretion of (14)C-mannitol, whereas small intestinal transit rate does not influence the timed urinary excretion of (51)Cr-EDTA.

Adult↗
PubMed1977

Michaëlis--Menten kinetics of phenazone elimination in the perfused pig liver.

The purpose of the present study was to define the elimination kinetics of phenazone (NFN) in the isolated perfused pig liver. In five experiments phenazone was administered as constant infusion to obtain steady-state periods over a wide range of concentrations. The elimination of phenazone followed saturation kinetics (concentrations 0.1-12 mmol x 1(-1) and the maximal elimination rate (Vmax) was on average 102 mumol x min-1 x kg-1 liver and the Michaëlis-constant (Km) of 2.6 mmol x 1(-1). Estimates of Vmax and Km for the microsomal phenazone hydroxylase activity measured in liver biopsies found to be considerably lower than in the perfused liver. The hepatic elimination of phenazone during perfusion of pig liver at phenazone concentrations corresponding to human therapeutic doses follows first-order kinetics.

Animals↗
PubMed1976

The effect of vasopressin and triglycyl lysine vasopressin (glypressin) on the splanchnic circulation in cirrhotic patients with portal hypertension.

In four cirrhotic patients with portal hypertension we have measured some hemodynamic parameters over 60-120 min; portal venous pressure, hepatic venous pressure, mean arterial blood pressure, hepatic blood flow, transsinusoidal vascular resistance and splanchnic oxygen uptake under treatment with Vasopressin (1 IU/min for 10 min) and glypressin (50 mug/kg body weight). The effect on the parameters was less pronounced with glypressin but of longer duration.

Abdomen↗