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J E Saffitz

Publications and source records attributed to J E Saffitz.

At least 127 records · Page 7Linked to original sources
PubMed1988

Delineation of the distribution of beta-adrenergic receptor subtypes in canine myocardium.

beta 2-Receptors constitute only 10-30% of the total beta-adrenergic receptors in mammalian ventricular myocardium, but their precise tissue location cannot be determined easily by measuring physiological variables. To delineate the distribution of beta-receptor subtypes in myocytic and vascular components of the heart, we incubated transmural sections of canine left ventricle with [125Iodo]cyanopindolol and selected concentrations of the beta 1-selective antagonist betaxolol or the beta 2-selective antagonist ICI 118,551. Detailed competition binding data were best accounted for by a two-site model in which approximately 75% of total sites were beta 1- and 25% were beta 2-receptors. The relative proportions of beta-receptor subtypes in myocytic and vascular components were assessed autoradiographically by analyzing the density of binding sites in transmural sections incubated with radioligand and subtype-selective displacers. Betaxolol (10(-7) M) reduced the density of radioligand binding sites by 44% in regions composed primarily of ventricular myocytes but by less than 5% in small coronary arterioles. ICI 118,551 (10(-7) M) reduced radioligand binding-site density by 18% in myocytic regions and by 55% in small arterioles. In myocytic regions, these data indicated a subtype composition of approximately 85% beta 1- and 15% beta 2-sites. In contrast, arterioles contained almost exclusively the beta 2-subtype. The diameters of coronary vessels in which beta 2-receptors were found to be selectively increased fell within a narrow range (mean +/- SD, 35 +/- 11 microns; range, 16-55 microns). Small mural arteries and venules did not contain a significantly higher proportion of beta 2-receptors than adjacent myocytic regions.

Animals↗
PubMed1988

Detection of rejection of canine orthotopic cardiac allografts with indium-111 lymphocytes and gamma scintigraphy.

Previous studies have demonstrated the feasibility of detecting canine heterotopic cardiac allograft rejection scintigraphically after administration of 111In lymphocytes. To determine whether the approach is capable of detecting rejection in orthotopic cardiac transplants in which labeled lymphocytes circulating in the blood pool may reduce sensitivity, the present study was performed in which canine orthotopic cardiac transplants were evaluated in vivo. Immunosuppression was maintained with cyclosporine A (10-20 mg/kg/day) and prednisone (1 mg/kg/day) for 2 wk after transplantation. Subsequently, therapy was tapered. Five successful allografts were evaluated scintigraphically every 3 days after administration of 100-350 microCi 111In autologous lymphocytes. Correction for labeled lymphocytes circulating in the blood pool, but not actively sequestered in the allografts was accomplished by administering 3-6 mCi 99mTc autologous erythrocytes and employing a previously validated blood-pool activity correction technique. Cardiac infiltration of labeled lymphocytes was quantified as percent indium excess (%IE), scintigraphically detectable 111In in the transplant compared with that in blood, and results were compared with those of concomitantly performed endomyocardial biopsy. Scintigraphic %IE for hearts not undergoing rejection manifest histologically was 0.7 +/- 0.4. Percent IE for rejecting hearts was 6.8 +/- 4.0 (p less than 0.05). Scintigraphy detected each episode of rejection detected by biopsy. Scintigraphic criteria for rejection (%IE greater than 2 s.d. above normal) were not manifest in any study in which biopsies did not show rejection. Since scintigraphic results with 111In-labeled lymphocytes were concordant with biopsy results in orthotopic cardiac transplants, noninvasive detection of graft rejection in patients should be attainable with the approach developed.

Animals↗
PubMed1987

Data acquisition system for maximum-likelihood analysis of electron microscopic autoradiographs.

EMAMAP is a program for the data acquisition phase of maximum-likelihood analysis of electron microscope autoradiographs. This program is written in C and has been implemented on a Masscomp MC-500 which supports a graphics processor and a digitizing tablet. The image analysis is automated at a low level: the program operator outlines the edges of the structures of interest using the digitizing tablet, while contiguous regions formed by closed contours are automatically filled by the software. The resulting image is compressed for efficient storage by a quadtree encoding technique for which data compression ratios of greater than 25:1 have been achieved. In practical terms, this implies that the data from a typical experiment of 50 autoradiographs could be stored on a single floppy disk. The system is currently in use for acquiring actual biological experimental data.

Autoradiography↗
PubMed1987

Lysophospholipids, long chain acylcarnitines and membrane dysfunction in the ischaemic heart.

Several findings suggest that the accumulation of ions and metabolites contribute to the electrophysiological alterations and associated malignant arrhythmias in the ischaemic heart. Our studies have focused on two amphipathic metabolites, lysophosphoglycerides (LPGs) and long-chain acylcarnitines (LCA). In an attempt to implicate any metabolite as contributing to the early electrophysiological alterations or subsequent development of irreversible cell injury in the ischaemic heart, several methodological and interpretative issues must be addressed, including the time course of accumulation and subcellular distribution. Current findings include: (1) both LPGs and LCA increase in ischaemic myocardium within 3 min, although the precise subcellular distributions have yet to be clarified, (2) electrophysiological alterations, analogous to those seen during ischaemia, are induced in vitro by both LPGs and LCA when as little as 1 mol% is incorporated into the sarcolemma (SL) based on EM autoradiography, (3) electrophysiological effects of LPGs are dependent on extracellular delivery, based on studies using intracellular pressure microinjection, (4) LPGs increase in both cardiac lymph and venular effluents in vivo within minutes to concentrations sufficient to induce electrophysiological alterations, (5) LCA increases in rat myocytes in vitro during hypoxia with a 5-fold increase in the SL determined by quantitative EM autoradiography. Inhibition of carnitine acyltransferase I (CAT-I) during hypoxia prevents not only the SL accumulation of LCA but also the associated electrophysiological alterations. Since the two major catabolic enzymes for LPGs are inhibited by LCA, studies are currently underway to assess the effects of inhibition of CAT-I during ischaemia in vivo, on both LCA and LPG accumulation and the influence on regional electrophysiological alterations and arrhythmogenesis.

Animals↗
PubMed1987

Biochemical and subcellular distribution of arachidonic acid in rat myocardium.

Selective release of arachidonic acid from prelabeled phospholipid pools has been observed following exposure of neonatal rat cardiac myocytes to metabolic inhibitors in vitro and has been correlated temporally with the development of irreversible sarcolemmal damage. Hydrolysis of phospholipids with release of arachidonic acid may be an important mechanism in the pathogenesis of sarcolemmal damage induced by ischemia. To elucidate potential subcellular loci of arachidonic acid release in ischemic myocardium, we characterized the phospholipid composition of adult rat myocardial sarcolemma and delineated the biochemical and subcellular distribution of radiolabeled arachidonic acid in neonatal rat myocytes incubated with [3H]-arachidonic acid for selected intervals. Although arachidonic acid comprised 13 +/- 3% of total aliphatic moieties in combined choline and ethanolamine glycerophospholipids isolated from purified adult rat myocardial sarcolemma, radiolabeled arachidonic acid could not be detected in sarcolemma of cultured neonatal rat myocytes incubated with 5 nM [3H]arachidonic acid for 24 h. Radioactivity was located almost exclusively in mitochondria and internal cytoplasmic membranes (primarily sarcoplasmic reticulum), which collectively contained 90% of myocyte radioactivity. These results indicate that radiolabeled arachidonic acid released from prelabeled phospholipid pools on exposure of neonatal rat myocytes to oxidative inhibitors is derived from mitochondria and internal cell membranes. The diminutive labeling of the sarcolemma suggests that turnover of arachidonoyl phospholipids is slower in the sarcolemma than in other membranous organelles.

Animals↗
PubMed1987

Interobserver variability in the pathologic interpretation of endomyocardial biopsy results.

Controversy exists over the role of endomyocardial biopsy in evaluating patients with dilated cardiomyopathy, particularly in detecting myocarditis and in assessing prognosis. Interobserver variability, if high, could explain conflicting reports. To assess this possibility, we submitted biopsy specimens from 16 patients with dilated cardiomyopathy to seven cardiac pathologists. The same slides were independently reviewed by each and assessed for fibrosis, hypertrophy, nuclear changes on a 0 to 3+ scale, mean lymphocyte count per high-power field, and myocarditis. The prevalance of significant fibrosis ranged from 25% to 69%, hypertrophy from 19% to 88%, nuclear changes from 31% to 94%, and abnormal lymphocyte count from 0 to 38%. One or more pathologists diagnosed definite or possible myocarditis in 11 of the 16 patients. Of these 11 patients, three pathologists agreed about three and two pathologists agreed about five. Myocarditis was diagnosed by a single pathologist in three cases. We conclude that interobserver variability is high in interpreting biopsy specimens from patients with dilated cardiomyopathy and that quantitative and standardized methods are needed to increase diagnostic consistency.

Adult↗
PubMed1987

Noninvasive detection of rejection of transplanted hearts with indium-111-labeled lymphocytes.

To determine whether cardiac transplant rejection can be detected noninvasively with indium-111 (111In)-labeled lymphocytes, we studied 11 dogs with thoracic heterotopic cardiac transplants without immunosuppression and five dogs with transplants treated with cyclosporine (10 mg/kg/day) and prednisone (1 mg/kg/day). All were evaluated sequentially with gamma scintigraphy after administration of 150 to 350 muCi of autologous 111In-lymphocytes. Technetium-99m-labeled red blood cells (1 to 3 mCi) were used for correction of radioactivity in the blood pool attributable to circulating labeled lymphocytes. Lymphocyte infiltration was quantified as the ratio of indium in the myocardium of the transplant or native heart compared with that in blood (indium excess, IE). Results were correlated with mechanical and electrical activity of allografts and with histologic findings in sequential biopsy specimens. In untreated dogs (n = 11), IE was 15.5 +/- 7.0 (SD) in transplanted hearts undergoing rejection and 0.4 +/- 1.1 in native hearts on the day before animals were killed (p less than .01). In dogs treated with cyclosporine and prednisone (n = 5), IE was minimal in allografts during the course of immunosuppression (0.8 +/- 0.4) and increased to 22.9 +/- 11.1 after immunosuppression was stopped. Scintigraphic criteria of rejection (IE greater than 2 SD above that in native hearts) correlated with results of biopsies indicative of rejection and appeared before electrophysiologic or mechanical manifestations of dysfunction. Thus infiltration of labeled lymphocytes in allografts, indicative of rejection, is detectable noninvasively by gamma scintigraphy and provides a sensitive approach potentially applicable to clinical monitoring for early detection of rejection and guidance for titration of immunosuppressive measures.

Animals↗
PubMed1987

Intramuscular administration of human tissue-type plasminogen activator in rabbits and dogs and its implications for coronary thrombolysis.

To determine whether sustained plasma concentration of human tissue-type plasminogen activator (t-PA) can be induced promptly after intramuscular injection with enhancers of absorption devoid of deleterious local and systemic effects, we studied 250 rabbits and 13 dogs. In rabbits with t-PA injected directly into exposed muscle followed by local electrical stimulation at the site, early absorption was increased markedly by addition of 0.63M methylamine plus 0.079M hydroxylamine to the excipient. Elevations peaked within 5 min and increased with dose of t-PA, concentration of methylamine, and volume of injection medium. The enhancers were effective with percutaneous injections in the absence of local electrical stimulation as well. They did not elicit any obviously deleterious local or systemic effects. In separate experiments in rats, intramuscular injections of 0.63M methylamine plus 0.079M hydroxylamine induced local egress of intravascular radiolabeled albumin within the injection site and endothelial gaps in venules detected with colloidal carbon--changes consistent with direct effects on vascular permeability. In dogs, percutaneous intramuscular injection of t-PA in excipient without enhancers did not lead to early elevations of human t-PA in plasma, although late elevations were seen. When the enhancers were used, early elevations occurred as well, with functional activity documented by fibrin plate assays of serially obtained plasma samples and by sequential coronary angiography delineating thrombolysis after experimentally induced coronary thrombosis. The results indicate that intramuscular administration of t-PA with selected enhancers of absorption is a feasible approach for rapid induction of fibrinolysis.

Absorption↗
PubMed1987

Quantitative ultrasonic characterization of the nature of atherosclerotic plaques in human aorta.

To determine the feasibility of quantitative ultrasonic techniques to define the composition of atherosclerotic plaques, samples of freshly excised human aortas were sewn to a sample holder and immersed in a saline bath for ultrasonic interrogation. Integrated backscatter of a 2-microsecond portion of the backscattered radiofrequency signal was measured with a 10 MHz focused transducer. Integrated backscatter was calculated by normalizing the root-mean-square voltage of the gated signal to the root-mean-square voltage obtained by replacing the tissue sample with a nearly perfect reflector. Microscopic examination of the 124 interrogated sites allowed differentiation of normal, fibrous, fibrofatty, and calcified regions. A site was considered calcified if it contained any histochemically detectable calcium. Values of integrated backscatter were markedly elevated from calcified regions (-30.0 +/- 6.4 dB, n = 25; mean +/- SD; p less than 0.001) compared to normal (-43.2 +/- 2.4 dB, n = 20) and fibrofatty (-43.9 +/- 3.4 dB, n = 43) sites. Values from fibrous regions (-40.7 +/- 3.8 dB, n = 36) were also significantly different compared with the calcified and fibrofatty regions (p less than 0.001). Thus, we have demonstrated that quantitative ultrasonic backscatter identifies and differentiates calcification and fibrosis in atherosclerotic sites offering promise for the noninvasive assessment of the pathologic status of the arterial wall.

Aorta↗
PubMed1987

Quantitative autoradiographic delineation of the distribution of beta-adrenergic receptors in canine and feline left ventricular myocardium.

The distribution of adrenergic receptors in specific components of the heart such as vessels and myocytes cannot be determined easily with assays of membranes prepared from homogenates of whole tissue. Accordingly, we characterized the binding of the potent nonsubtype selective antagonist [125iodo]cyanopindolol to beta-receptors in unfixed transmural slices of feline and canine left ventricle. Specific binding ratios greater than 90% were achieved at radioligand concentrations near Kd and greater than 80% at saturating ligand concentrations. Binding of radioligand to receptors in transmural slices was rapid, saturable, stereoselective, and displaceable by antagonists and agonists with the rank order of potency expected of beta-adrenergic receptors. Analysis of binding isotherms indicated maximum binding capacities of 27.8 +/- 6.6 and 40.6 +/- 5.1 fmol/mg tissue protein and dissociation constants of 10.1 +/- 1.8 and 21.3 +/- 1.6 pM in feline and canine ventricular slices, respectively. The distribution of beta-receptors in myocytes and selected vascular components of the heart was determined with quantitative film autoradiography and high resolution computer-based analysis and display of the density of binding sites, maximum binding capacity, and binding affinity measurements. The results of autoradiographic analysis revealed a uniform transmural distribution of receptors in regions composed primarily of ventricular myocytes but an inverse relation between the density of beta-receptors and the diameter of coronary vessels. Large epicardial conductance arteries had half the receptor density of subjacent myocytes; small mural arteries had approximately 60% of the beta-receptor density of nearby myocytes, and the coronary resistance arterioles had the highest receptor density of any vascular compartment, which was equivalent to that of myocytes. The methods developed should be of particular value in characterizing the distribution and function of receptor subtypes and mechanisms of regulation of adrenergic responsiveness in intact myocardium.

Animals↗
PubMed1987

Exaggerated atrial arachidonate metabolism in rabbit left ventricular myocardial infarction.

Isolated perfused rabbit hearts that have previously been subjected to in vivo left ventricular myocardial infarction respond to N-formylmethionyl-leucyl-phenylalanine (fMLP) or bradykinin (BK) administration with the synthesis of large quantities of eicosanoids. To anatomically localize these synthetic responses we studied the effects of fMLP and BK on eicosanoid synthesis in isolated atria and isolated perfused ventricles from normal and infarcted (4 d in vivo) rabbit hearts. These studies revealed that enhanced agonist-stimulated eicosanoid synthesis occurs largely in the right atria of infarcted hearts, a site distant from the zone of injury. Studies of exogenous arachidonate metabolism in microsomes prepared from various regions of the heart showed that while prostaglandin synthetic capacity is preferentially localized to the right atrium, right atria from normal and infarcted hearts have similar thromboxane and PGE2 synthetic capacity. These results demonstrate that enhanced agonist-stimulated eicosanoid synthesis following rabbit left ventricular myocardial infarction occurs largely in the right atrium, and that this effect is independent of the activity of prostaglandin synthetic enzymes.

4,5-Dihydro-1-(3-(trifluoromethyl)phenyl)-1H-pyraz↗
PubMed1987

Selective uptake of [3H]arachidonic acid into the dense tubular system of human platelets.

We have used quantitative electron microscopic autoradiography to characterize the subcellular distribution of arachidonoyl phospholipids following brief (5 minutes) exposure of unstimulated human platelets to [3H]arachidonic acid. Labeled arachidonate was taken up rapidly and incorporated into phospholipids. Phospholipid radioactivity was preserved and spatially fixed during tissue processing for electron microscopy. Analysis of autoradiographs showed that following a brief exposure to 750 nmol/L [3H]arachidonate, there is selective labeling of an internal membrane compartment composed of the dense tubular system and the open canalicular system. The plasma membrane, platelet granules, and nonmembranous cytoplasm were not labeled. Since the open canalicular system is continuous with the plasma membrane and since phospholipids in continuous membranes are freely diffusible, our observations indicate that [3H]arachidonate was incorporated into phospholipids within the dense tubular system and not the open canalicular system. Thus, the dense tubular system, known to contain cyclooxygenase activity, incorporates arachidonate selectively following brief exposure to this fatty acid, presumably to concentrate it in proximity to enzymes for icosanoid synthesis.

Arachidonic Acid↗
PubMed1987

Anti-B-mediated rejection of an ABO-incompatible cardiac allograft despite aggressive plasma exchange transfusion.

A group A recipient received a group B cardiac allograft. Aggressive plasma exchange with replacement by group AB FFP initially reduced the recipient's anti-B titer to a low level. Once a secondary anti-B response was mounted, plasma exchange was ineffective and IgM and IgG anti-B titers rose to high levels. Associated with the increased anti-B titers, cardiac function deteriorated and on day 13 the group B heart was replaced by a group A allograft. The compatible allograft functioned well initially but was eventually rejected, and the patient died 51 days after the initial transplantation. Histologic examination of the first allograft revealed a delayed form of typical antibody-mediated rejection with destruction of the microvasculature associated with antibody deposition and acute inflammation. By contrast, the histopathology of the second compatible allograft was typical of cell-mediated allograft rejection. Extracts of myocardium from the incompatible heart contained IgM and IgG anti-B, while no anti-B alloantibody was demonstrable in the extracts of the ABO-compatible allograft and a control heart. The utility of plasma exchange with group AB FFP replacement in such a circumstance requires further study.

ABO Blood-Group System↗
PubMed1987

Coronary atherosclerosis and thrombosis underlying acute myocardial infarction.

Autopsy and clinical studies indicate that coronary thrombosis plays a key role in the development of acute transmural myocardial infarction and possibly in unstable angina and sudden cardiac death. The pathogenesis of coronary thrombosis is complex. It involves the dynamic interplay among the atherosclerotic arterial wall, vasomotor influences, cellular and humoral mediators, and the blood coagulation pathways.

Angina, Unstable↗
PubMed1987

Pathophysiology of myocardial reperfusion.

The feasibility of myocardial reperfusion is established. However, restoring patency to epicardial coronary arteries does not necessarily signify restoration of tissue perfusion or restoration of biochemical or mechanical function to the heart muscle previously supplied by the occluded vessel. This review examines the biochemical, functional, and histopathologic changes associated with myocardial reperfusion in an attempt to define the constraints within which reperfusion may lead to optimal recovery of myocardium, and to explore future possibilities for maximizing benefits of reperfusion while minimizing potential reperfusion injury.

Animals↗
PubMed1986

Relation of size of transmural acute myocardial infarct to mode of death, interval between infarction and death and frequency of coronary arterial thrombus.

Seventy-eight necropsy patients with transmural acute myocardial infarction (AMI) were studied to correlate the mode of death, the interval between onset of AMI and death and the presence or absence of coronary thrombus with the extent of the infarct. Infarct size was assessed quantitatively as a percentage of total left ventricular (LV) mass. Death was caused by cardiogenic shock in 16 patients (21%), arrhythmia in 31 patients (40%) and cardiac rupture in 24 patients (31%). The mean interval between the onset of AMI and death was 12 +/- 13 days. Infarct size averaged 23 +/- 14% of LV mass. Patients who died in cardiogenic shock had the largest infarcts (37 +/- 11%) and those who died of cardiac rupture had the smallest infarcts (15 +/- 9%) and the shortest interval between onset of AMI and death (7 +/- 8 days). Coronary thrombi were present in 58 patients (74%). When present, thrombus was observed in the coronary artery that had supplied the infarct area and was superimposed on advanced atherosclerotic plaque, but no relation was found between extent of luminal obstruction by thrombus and AMI size. The absence of coronary thrombus at necropsy was associated with either small infarcts or prolonged survival after AMI.

Aged↗
PubMed1986

The dependence of electrophysiological derangements on accumulation of endogenous long-chain acyl carnitine in hypoxic neonatal rat myocytes.

To determine whether accumulation of long-chain acyl carnitine contributes to electrophysiological abnormalities induced by hypoxia, we characterized effects of normoxic and hypoxic perfusion on the subcellular distribution of endogenous long-chain acyl carnitine and transmembrane potentials of cultured rat neonatal myocytes. Hypoxia increased long-chain acyl carnitine more than 5-fold. Sodium 2-[5-(4-chlorophenyl)-pentyl]-oxirane-2-carboxylate (10 microM), a carnitine acyltransferase inhibitor, precluded accumulation of long-chain acyl carnitine induced by hypoxia. Tissue was processed for electron microscopy by a procedure specifically developed for selective extraction of endogenous short-chain and free carnitine but retention of endogenous long-chain acyl carnitine. In normoxic-perfused cells, long-chain acyl carnitine was concentrated in mitochondria and cytoplasmic membranous components. Only small amounts were present in sarcolemma. Hypoxia increased mitochondrial long-chain acyl carnitine by 10-fold and sarcolemmal long-chain acyl carnitine by 70-fold. After 60 minutes of hypoxia, sarcolemma contained 1.4 X 10(7) long-chain acyl carnitine molecules/micron 3 of membrane volume, a value corresponding to approximately 3.5% of total sarcolemmal phospholipid. Hypoxia also significantly decreased maximum diastolic potential, action potential amplitude and maximum upstroke velocity of phase 0. Sodium 2-[5-(4-chlorophenyl)-pentyl]-oxirane-2-carboxylate inhibited accumulation of long-chain acyl carnitine in each subcellular compartment and prevented the depression of electrophysiological function induced by hypoxia. These results strongly implicate endogenous long-chain acyl carnitine as a mediator of electrophysiological alterations induced by hypoxia.

Animals↗