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Biomedical subjects

T Sandor

Publications and source records attributed to T Sandor.

At least 55 records · Page 3Linked to original sources
PubMed1985

Intravenous digital subtraction angiography in diagnosis of vascular graft occlusion.

Differentiation is often difficult between vascular graft occlusion and progression of underlying disease in patients after vascular surgery. We have studied 57 patients after surgery for traumatic and atherosclerotic arterial occlusion and other vascular anomalies using a commercial digital subtraction angiography (DSA) unit; no complications occurred. Indications for examination included pain, diminished pulse, and failure of catheter angiography. Graft patency was established if proximal and distal anastomoses were visualized; occlusion was diagnosed if no graft was imaged or vascular stump found--noted in 31 grafts. Our diagnosis was proved surgically in 24 patients (two refused operation); three others were confirmed angiographically and one by Doppler ultrasonic examination. In our experience DSA is a safe, specific means of following postoperative grafts and diagnosing their occlusion.

Angiography↗
PubMed1985

Statistical considerations on the precision of assessing blood vessel diameter in cine coronary angiography.

Problems related to the precision of computerized measurement and analysis of blood vessel diameter from digitized cineangiographic vessel images are described, and shortcomings of the conventional definition of percent stenosis are discussed. Formulae for the precision of percent stenosis, for the minimum significant measurable changes in blood vessel diameter, for the necessary scanning resolution, and for absolute vessel diameter measurement are provided. A Monte Carlo procedure-based technique for assessing the effect of radiographic noise on the location of vessel boundaries within the transverse densitometric image profile is presented and applied to contrast-filled cylindrical phantoms. The results demonstrate the feasibility for achieving subpixel resolution in computerized detection of vessel edges and diameter measurement.

Cineangiography↗
PubMed1985

A profile of the intestinal mucosal corticosteroid receptors in the domestic duck.

The corticosteroid receptor profile of the intestinal tract of the domestic duck (maintained on either a low-sodium (LS) or a high-sodium (HS) diet) was investigated. Using tritiated triamcinolone acetonide (TA), corticosterone, or aldosterone as ligands, cytoplasmic mineralocorticoid receptors (MR, type I) and glucocorticoid receptors (GR, type II) were found in the mucosal cytosol of the jejunum and colon with the following binding parameters: LS jejunum GR-Kd, 3.4 nM; Nmax, 245 fmol/mg protein; MR-Kd, 0.54 nM; Nmax, 35 fmol/ mg protein; colon GR-3.2 nM; Nmax, 531 fmol/mg protein; MR-Kd, 0.55 nM; Nmax, 113 fmol/mg protein; HS jejunum GR--Kd, 3.2 nM; Nmax, 531 fmol/mg protein; MR--Kd, 0.30 nM; Nmax, 50 fmol/mg protein; colon GR--Kd, 1.1 nM; Nmax, 572 fmol/mg protein; MR--Kd, 0.68 nM; Nmax, 221 fmol/mg protein. The diet little influenced the GR binding parameters, while the MR (aldosterone) binding parameters showed a down-regulation following LS (high circulating aldosterone) diets. The competition hierarchy of radioinert steroids on the formation of the [3H]corticosterone-receptor complex was corticosterone = cortisol = 11-deoxycorticosterone greater than aldosterone = TA = dexamethasone much greater than 11-deoxycortisol; with [3H]aldosterone, the competition was corticosterone = progesterone = 11-deoxycorticosterone greater than aldosterone = cortisol = TA = dexamethasone greater than 11-deoxycortisol greater than 11-dehydrocorticosterone. The intestinal mucosal receptor was deactivated following treatment with trypsin. On linear sucrose gradients, receptor-ligand complexes sedimented with a single peak at 8.5 S (hypotonic gradient) and 4.0-4.5 S (hypertonic gradient), respectively. Heat-activated [3H]TA- and [3H]aldosterone-receptor complexes bound avidly to DNA-cellulose and, upon ion-exchange chromatography on DEAE-Sephacel, the presence of the negatively charged unactivated and the more positively charged activated complexes could be shown. The hydrodynamic parameters, determined by gel-filtration chromatography, gave for all three ligand-receptor complexes molecular weight values from 334,000 to 351,000 and Stokes radii from 76.8 to 80.0 A. From these studies it was concluded that the duck intestinal tract possesses vertebrate-type GR and MR, though these receptors were much less specific than their mammalian counterparts. The duck intestinal corticosteroid receptor was found to be different from those of the teleost fish and anuran amphibian, establishing the possibility of a biochemical evolution in nonmammalian intestinal corticosteroid receptor conformation.

Aldosterone↗
PubMed1985

Zonal parametric imaging: concept and application to renal angiography.

A new method is described that modifies the original concept of parametric or functional imaging. While the conventional parametric image replaces a temporal sequence of images with a single static image based upon a selected parameter, in the new approach fixed zonal areas and bands are established within the imaged organ, and the mean value for each zone is computed. It is shown that parametric images can be quantified and objectively compared in this way. The algorithm has been implemented to analyze renal studies.

Angiography↗
PubMed1985

Inotropic stimulation of reperfused myocardium with dopamine: effects on infarct size and myocardial function.

Prolonged postischemic ventricular dysfunction ("stunned myocardium") may be responsible for heart failure after myocardial reperfusion. Although inotropic stimulation can enhance the contractility of stunned myocardium, it could potentially increase infarct size and thereby impair ultimate recovery of myocardial function. In 16 anesthetized dogs, the left anterior descending coronary artery was occluded for 2 hours, and then reperfused. At 45 minutes of reperfusion, the dogs were randomized to receive a 3 hour intravenous infusion of either saline solution or dopamine (10 micrograms/kg per min), and 1 hour after the infusion was discontinued the area of necrosis and an in vivo area at risk of necrosis were determined. All dogs had serial two-dimensional echocardiograms with computer-assisted analysis and in vivo biopsies for determination of adenosine triphosphate and creatine phosphate levels. Dopamine caused an increase in the contractility of the reperfused myocardium, with systolic wall thickening increasing from -4.1 +/- 2.6 (mean +/- SEM) to +24.0 +/- 3.7% (p less than 0.002) and short-axis cross-sectional ejection fraction increasing from 27.1 +/- 4.7 to 71.6 +/- 4.4% (p less than 0.002) after 15 minutes of infusion. Regional myocardial blood flow in the previously ischemic epicardium was increased from 1.18 +/- 0.11 ml/min per g with saline to 2.95 +/- 0.36 ml/min per g with dopamine (p less than 0.03).(ABSTRACT TRUNCATED AT 250 WORDS)

Adenosine Triphosphate↗
PubMed1984

Response of reperfusion-salvaged, stunned myocardium to inotropic stimulation.

The purpose of this study was to determine whether myocardium salvaged by reperfusion following coronary occlusion could respond to inotropic stimulation by dopamine. Mongrel dogs underwent a 2-hour occlusion of the proximal left anterior descending coronary artery, followed by reperfusion for 5 or 28 hours. Dopamine (5 to 10 micrograms/kg/min) or dextrose was administered 1 hour or 24 hours after the onset of reperfusion. Serial, computer-assisted, two-dimensional echocardiographic determination of percentage of systolic wall thickening (%SWT) and cross-sectional ejection fraction (% delta area) were used to evaluate the response to treatment. Myocardium in the region of central ischemia contracted poorly after 1 hour of reperfusion (mean %SWT = 1.3 +/- 13.3% [mean +/- SD] compared to preocclusion value of 43.6 +/- 18.5%, p less than 0.001) and tended to thin at 24 hours of reperfusion (mean %SWT = -6.0 +/- 12.3%, p less than 0.001). After 1 hour of reperfusion, dopamine produced a greater than fourfold improvement in %SWT within the reperfused zone (to 15.3 +/- 7.3%, p less than 0.05). After 24 hours of reperfusion, dopamine again produced an improvement in %SWT (to 5.8 +/- 12.5%, p less than 0.05). There were no significant changes in %SWT with dextrose infusion. Thus, dopamine stimulates the reperfusion-salvaged but noncontracting (stunned) myocardium to contract as early as 1 hour after reperfusion.

Animals↗
PubMed1984

Left ventricular wall motion analysis using operator-independent contour positioning.

A method has been developed for the analysis of left ventricular wall motion which obviates the operator's involvement in the relative positioning of the systolic and diastolic contours. This was achieved by maximizing the cross-correlation function for the two silhouettes . The technique was compared with a standard method requiring the operator's definition of a long axis for the left ventricle. The results for 21 normal angiograms showed that with the cross-correlation technique the confidence region of the wall motion curves was markedly narrower and the symmetry in the contractile pattern between the anterior and posterior wall segments was better than with the standard technique. Statistical concepts for narrowing the normal group and the sources of errors in the analysis are discussed.

Adult↗
PubMed1984

Glucocorticoid receptors in the gill tissue of fish.

The presence of glucocorticoid-binding macromolecular receptors was demonstrated in the Na2MO4 (10 mM)-stabilized gill cytosol of the American eel, Anguilla rostrata and in that of the trout, Salmo gairdneri. In all experiments, tritiated triamcinolone acetonide [( 3H]TA) was used as ligand. In the eel, the steroid was bound with a KD of 2.84 +/- 0.4 nM and an Nmax of 188 +/- 34 fmol/mg protein. The binding parameters for the trout cytosol were KD = 1.43 +/- 0.13 nM; Nmax = 271 +/- 113 fmol/mg protein. Competition studies with [3H]TA-labeled eel gill cytosol and radioinert steroids gave the following binding hierarchy: TA greater than dexamethasone greater than cortisol greater than 11-deoxycortisol greater than 21-deoxycortisol. Aldosterone, estrogens, or androgens did not complete. The eel gill receptor was deactivated by prior treatment with trypsin or mersalyl. RNase was without effect, but DNase degraded the receptor except when used in the presence of trypsin inhibitor. The eel gill TA-receptor complex sedimented on a linear (10-30%) sucrose gradient with a single peak at 7.0 S or 3.5 S, in hypotonic or hypertonic (0.4 M KCl) gradients, respectively. The eel ligand-receptor complex did not bind, following heat activation, to DNA-cellulose or phospho-cellulose, though it bound to DEAE-cellulose. In this respect, it behaved similarly to the eel intestinal mucosal TA-receptor complex, described previously. The initiation of dissociation of the eel receptor-[3H]TA complex with excess TA yielded pseudo-first-order dissociation kinetics (k-1 at 0 degree C: 2.39 X 10(-5) S-1), while the association kinetics of the receptor with the ligand was of second order (k + 1: 2.51 X 10(4) M-1 S-1). Sepharose column chromatography indicated a molecular weight of 334,690 Da. Calculation of the Stokes radius gave a value of 84.5 A and the frictional ratio, calculated from the molecular weight, was 1.84. From these data it was concluded that the gills of these two euryhaline teleosts contain tetrapod-type glucocorticoid receptors. These studies are the first to demonstrate these steroid recognition molecules in fish gill. The presence of receptors in the fish gill tissue are in agreement with the physiological action of corticosteroids in allowing adaptation of the animals to habitats of different salinity.

Anguilla↗
PubMed1984

Quantitative analysis of left ventricular function: pre- and postischemic two-dimensional echocardiography in dogs.

A quantitative technique that aligns the diastolic and systolic silhouettes was used to assess left ventricular function (wall thickening and endocardial wall motion) from two-dimensional echocardiographic studies for every 2 degrees of arc of the left ventricular circumference in canines. Thirty-two dogs were studied before and at specific intervals up to 14 days after either temporary or permanent occlusion of the left anterior descending coronary artery. Decreased systolic wall thickening and frank systolic thinning were observed in the ischemic/infarcted region 90 min and 6 hr after occlusion; endocardial motion showed the abnormally contracting segment less clearly. Partial recovery was seen in both groups of animals but to a greater degree in those with temporary occlusion. The technique was useful for assessing sequential changes in wall motion.

Animals↗
PubMed1983

Quantitative computer-assisted analysis of left ventricular wall thickening and motion by 2-dimensional echocardiography in acute myocardial infarction.

Quantitative regional wall motion analyses of 2-dimensional echocardiograms (2-D echo) have usually focused on large arcs (greater than 45 degrees) of the left ventricular (LV) perimeter rather than on small LV zones. Few studies have assessed changes in wall thickness. To determine normal ranges of regional LV function, the endocardial and epicardial contours of short-axis 2-D echoes obtained at the papillary muscle level of 10 normal subjects were manually traced. Then, 15 patients with acute myocardial infarction (MI) were studied, comparing their contours at admission with ranges determined from the normal subjects. In all patients with MI, 2-D echoes located abnormal wall motion involving at least the region identified as abnormal by the electrocardiogram and often extending into adjacent regions. All 9 patients with transmural MI had either decreased wall thickening or abnormal endocardial wall motion; all except 1 had focal thinning in the region of the MI. Of the 6 patients with nontransmural MI, 2 had abnormal endocardial wall motion, and all had decreased wall thickening. Evaluating regional wall motion at multiple points around the LV circumference should permit more precise delineation of LV function in health and disease than has been heretofore possible.

Adult↗
PubMed1983

The minimum error in estimating coronary luminal cross-sectional area from cineangiographic diameter measurements.

A formal analysis of the error associated with the use of radiographic diameter measurements in estimating the luminal area of an elliptically-shaped coronary cross-section was performed. When two views are available, the maximum potential error was found to decrease rapidly as the angle between the views increased to 90 degrees, but this error was small (less than 25%) for orthogonal views only for mild degrees of ellipticity (major/minor axis ratio less than 2). Since, for each successive doubling of the number of radiographic views, a stepwise reduction in the potential error by an approximate factor of only one-half was found, a large number of views is required to eliminate the potential error associated with diameter assessment of highly elliptical lumena.

Cineangiography↗
PubMed1983

Intestinal triamcinolone acetonide receptors of the eel (Anguilla rostrata).

The binding of [6,7-3H]triamcinolone acetonide (TA) to intestinal mucosa of freshwater-adapted silver eels was studied. The cytoplasmic preparations bound the ligand with an equilibrium dissociation constant (KD) of 2.28 +/- 0.37 nM and the maximal number of binding sites (Nmax) was 960 +/- 55 fmol/mg of protein (+/- SE, n = 13). Scatchard analysis indicated the presence of a single species of binding sites. Binding was abolished following treatment of the cytosol with trypsin, N-ethylmaleimide, or Mersalyl, but DNase or RNase treatment had little effect. The competition hierarchy of radioinert steroids on the formation of the [3H]TA-receptor complex was TA greater than dexamethasone greater than cortisol greater than 11-deoxycortisol. Aldosterone, DOC, corticosterone, 11-dehydrocorticosterone, progesterone, testosterone, or estradiol-17 beta did not compete. Sedimentation of the [3H]TA-receptor complex on a linear sucrose gradient (10-30% + 10% v/v glycerol) yielded single peaks in the absence or presence of 0.4 M KCl in the gradient (6 S or 3.5 S respectively). Following heat activation the receptor-ligand complex was freely translocated to homologous nuclei in vitro, though the activated complex did not bind to DNA-cellulose. It was concluded that the eel intestinal mucosal cytosol contains a high-affinity-low capacity steroid receptor system. This is the first instance that such a system was demonstrated in fish tissue.

Animals↗
PubMed1983

Quantitative analysis of left ventricular wall motion and thickness using two-dimensional echocardiography.

The real time two-dimensional ultrasonic imaging of the left ventricle made possible segmental echocardiographic measurements of wall motion and thickening and thinning. The underlying hypothesis is that measurements of regional wall motion could quantify the extent of myocardial ischemia and infarction; the method could be used as a truly non-invasive tool to assess the severity of damage from infarction and the effects of interventions designed to limit infarcts. The method is operator interactive. Each patient's data could be compared with data for a normal group. The selection criteria for the normal patients have been described. The confidence region of the normal group and the effect of averaging over three tracings for three heartbeats have been computed. Technical difficulties inherent in the method and possible improvements are discussed.

Computers↗
PubMed1983

Further studies on the corticosteroid-receptor system of the nasal gland of the domestic duck (Anas platyrhynchos).

The interaction of tritiated corticosterone with the nasal gland corticosterone receptor was investigated. Kinetic studies have shown that the association of [3H]corticosterone-receptor followed second-order reaction kinetics and the dissociation of the ligand from the receptor became "pseudo" first order in the presence of large excess of radioinert steroids at 0, 15, 25, and 35 degrees C. Similar data were obtained with an ammonium sulfate precipitate of the cytosol. Dissociation rate constants varied from 10(-5) to 10(-3) s-1 and the association rate constants varied from 0.5 X 10(4) to 3.8 X 10(5) M-1 X s-1, depending on the reaction temperature and the cytoplasmic receptor preparation. Equilibrium dissociation constants were in 10(-8)-10(-9) M range. Equilibrium dissociation constants, calculated from kinetic data (kd/ka), showed a marked temperature dependence, while those obtained by saturation analysis varied much less with the reaction temperature. Data obtained in these experiments were used to calculate some thermodynamic parameters of the binding of corticosterone to the cytoplasmic receptor. The enthalpy of dissociation was 101.5 and 79.4 kJ X mol-1 and the entropy of dissociation was 200 and 280 J X mol-1 X degree-1 for the crude cytoplasmic receptor and the ammonium sulfate precipitate, respectively. From the equilibrium dissociation constants, the enthalpy and entropy of the equilibrium binding was calculated. Polynomial fitting of Ka values versus 1/T yielded enthalpy (delta H) values from -0.9 to -88.8 kJ X mol-1, depending on the nature of the receptor preparation. Entropy values were negative for kinetically derived equilibrium association constants from the crude cytosol at all temperatures and for 0 and 15 degrees C for the precipitate. Entropy values were positive for Ka values obtained from kinetic rates at 25 and 35 degrees C and for Ka's calculated from saturation analysis. Further experiments with the precipitate confirmed our previous contention that the nasal gland cytoplasmic corticosterone receptor metabolized the bound ligand to 11-dehydrocorticosterone, though the receptor preparation was corticosterone specific. The following hydrodynamic parameters were obtained on the binding macromolecule: molecular weight, 316 000; S20W, 8.0; Stokes radius (rs), 77.3 A (1 A equal to 0.1 nm); total frictional ratio (f/f0), 1.71. The labeled receptor preparation translocated to homologous nuclear binding sites following heat activation and, at the nuclear binding sites, the ligand was almost exclusively in its oxidized form.(ABSTRACT TRUNCATED AT 400 WORDS)

Animals↗
PubMed1983

Computerized image analysis for quantitative measurement of vessel diameter from cineangiograms.

Subjective estimates of the angiographic severity of coronary artery stenoses show variability and inaccuracy. We therefore tested the accuracy of a newly developed computerized image analysis system for quantitating vessel diameter from cineangiograms. Fourteen cylindrical phantoms of known diameter were filled with contrast medium and filmed over a wide range of clinically relevant radiographic conditions in order to develop regression equations that related computer-derived to anatomic diameters. Computer measurements of vessel diameter were unaffected by vessel size, magnification, focal spot size, thickness of scattering medium, kilovolt peak, or location within the radiographic field, but a correction factor was necessary for a small but significant (p less than .01) linear dependence on contrast medium concentration. The accuracy of computerized vessel diameter measurements ranged between +/- 59 and +/- 137 mu for all conditions except for rapid vessel motion and contrast medium concentrations of 50% or less meglumine diatrizoate (Renografin 76), both of which resulted in reduced accuracy as well as in the inability to locate lumen edges of vessels less than 1 mm in diameter.

Cineangiography↗
PubMed1982

Retinal vascular reactivity to norepinephrine and angiotensin II in normals and diabetics.

Retinal arterial vasoconstriction induced by an infusion of angiotensin II or norepinephrine was investigated in eight normal controls (N), nine diabetics without retinopathy (DNR), and 10 diabetics with retinopathy (DR) by color fundus photographs taken before and after the infusions. Image analysis was done by a semiautomated computerized microdensitometer using a videoscanner. Normal controls and diabetics without retinopathy had a significant reduction in diameter compared with diabetics with retinopathy, who failed to constrict arterioles in response to either vasopressor. The mechanism of this phenomenon is unclear. Semiautomated computerized microdensitometry is reproducible and appears to be a sensitive technique to evaluate the vascular reactivity of the retinal vasculature.

Adult↗