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E T Fossel

Publications and source records attributed to E T Fossel.

16 recordsLinked to original sources
PubMed1992

Effects of tumor necrosis factor-alpha on peroxidation of plasma lipoprotein lipids in experimental animals and patients.

Changes in the plasma lipid composition are observed in patients and animals with malignancy and certain other diseases that are consistent with peroxidation of plasma lipoprotein lipids. These changes can be observed with water-suppressed proton (H-1) and carbon-13 (C-13) nuclear magnetic resonance spectroscopy (NMR) and gas chromatography. Gas chromatography provides evidence of a decrease in polyunsaturated fatty acids relative to monounsaturated fatty acids. This evidence is consistent with that observed by C-13 NMR spectroscopy. Mediators for these effects were sought. Cytokines, known to be released in response to malignant tumor cells and to affect lipid metabolism, were injected into normal mice and their effects on the H-1 and C-13 NMR spectra of plasma lipids were observed. Mouse recombinant tumor necrosis factor-alpha (mr-TNF-alpha) significantly decreased the H-1 methyl and methylene lipid linewidths, and the C-13 spectra indicated a decrease in the relative concentration of polyunsaturated fatty acids. The same changes were directly confirmed by gas chromatographic analysis, showing decreases in the amount of linoleic and arachidonic acids and other polyunsaturated fatty acids relative to monounsaturated fatty acids and in the ratio of polyunsaturated to monounsaturated fatty acids. Serial plasma samples from volunteers receiving an infusion of endotoxin showed similar changes in their C-13 NMR spectroscopy at times when peak TNF-alpha values were measured. In addition, in these samples the C-13 NMR spectra showed direct evidence of lipid peroxidation products. These changes were similar to those observed commonly in the plasma of cancer patients. Other cytokines (human recombinant interleukin-1 alpha [hr-IL-1 alpha], hr-IL-2, mouse recombinant interferon-gamma) did not produce these effects. We conclude that TNF-alpha is a mediator (but not necessarily the only one) of changes in plasma lipoprotein lipid composition due to peroxidation and that this is a mechanism for the changes observed in the NMR spectra of plasma from cancer patients and from normal animals injected with TNF-alpha.

Animals↗
PubMed1991

Selective cytotoxicity of low-density lipoprotein to helper T cells of cutaneous T-cell lymphoma after photoperoxidation with 8-methoxypsoralen.

Lymphocyte-containing plasma subjected to photolysis in the presence of 8-methoxypsoralen (methoxsalen, 8-MOP) has previously been shown to be effective against cutaneous T-cell lymphoma and the AIDS-related complex. The mechanism of this effect was thought to involve photoreaction of 8-MOP with DNA, based on certain in vitro experiments. The results of this study suggest a different mechanism. Low-density lipoprotein (LDL) from fresh human plasma was photosensitized by addition of 8-MOP and exposure to UV light (mp-LDL), and the reactions of the LDL lipids and the chemical actions induced by these reactions were monitored. In a separate procedure, LDL was peroxidized with hydrogen peroxide and peroxidase (p-LDL). mp-LDL and p-LDL were then tested in cytotoxicity assays on HuT-78 helper T cells of cutaneous T-cell lymphoma. These results indicate that (a) LDL in plasma in the presence of very low concentrations of 8-MOP (200 ng/mL) can be peroxidized by UV light; (b) this photoperoxidized LDL is cytotoxic to helper T cells of cutaneous T-cell lymphoma in a dose-dependent manner; but (c) it does not kill normal lymphocytes under similar conditions. The findings also suggest alternative therapeutic strategies for treatment of cutaneous T-cell lymphoma, such as direct utilization of peroxidized LDL.

Cell Survival↗
PubMed1991

Cooperativity in the calcium ion-induced quenching of the intrinsic fluorescence of a series of normal and GLA-deficient bovine prothrombin fragment 1 molecules.

Ca2+ titrations of the intrinsic fluorescence of a series of gamma-carboxyglutamic acid (GLA)-deficient bovine prothrombin fragments 1 yield response Hill plot parameters useful for characterization of the metal ion-binding process. 11-, 10-, and 9-GLA fragments 1 exhibit Tm (the (Ca2+)total concentration at which ln (B/F) = 0 in the response Hill plot) values between 0.2 and 0.3 mM. A 22-fold increase in Tm to 5.4 mM is observed for 8-GLA fragment 1. Tm decreases to 3.8 mM for the 7- and 6-GLA proteins. The value of h, about 2.8 +/- 0.2 for 11-, 10-, and 9-GLA fragments 1, abruptly decreases to 1.2-1.3 for 8-, 7-, and 6-GLA fragments 1. The observed degree of quenching induced by saturating levels of calcium ions is affected by both changes in the intrinsic fluorescence of the metal ion-free proteins and in the maximum possible degree of quenching in the presence of calcium. The kinetic characteristics of the calcium ion-induced quenching of the intrinsic fluorescence of 6-GLA fragment 1 are identical to those observed in 10-GLA fragment 1, suggesting that the fluorescence quenching observed in the 6- and 10-GLA fragments 1, while different in magnitude, involves similar processes. Observation of an abrupt change in the relative electrophoretic mobilities of 11- to 9-GLA fragments 1 compared to 8- to 6-GLA fragments 1, in the absence or presence of Ca2+, suggests the existence of a major protein conformation change which occurs concomitantly with the noted changes in Tm and h response Hill plot parameters. Molecular mechanics calculations suggest a structural hypothesis unifying these observations. Central to this model is the presumption of the existence of hydrogen bond-mediated interactions between metal ion-binding sites.

1-Carboxyglutamic Acid↗
PubMed1991

C-13 NMR spectroscopy of plasma reduces interference of hypertriglyceridemia in the H-1 NMR detection of malignancy. Application in patients with breast lesions.

We have previously described the application of water-suppressed proton nuclear magnetic resonance (H-1 NMR) spectroscopy of plasma for detection of malignancy. Subsequently, hypertriglyceridemia has been identified as a source of false positive results. We now describe a confirmatory, adjunctive technique--analysis of the carbon-13 (C-13) NMR spectrum of plasma--which also identifies the presence of malignancy but is not sensitive to the plasma triglyceride level. Blinded plasma samples from 480 normal donors and 208 patients scheduled for breast biopsy were analyzed by water-suppressed H-1 and C-13 NMR spectroscopy. Triglyceride levels were also measured. Among the normal donors, there were 38 individuals with hypertriglyceridemia of whom 18 had results consistent with malignancy by H-1 NMR spectroscopy. However, the C-13 technique reduced the apparent H-1 false positive rate from 7.0% to 0.6%. Similarly, in the breast biopsy cohort, C-13 reduced the false positive rate from 2.8% to 0.9%. Furthermore, the accuracy of the combined H-1/C-13 test in this blinded study was greater than 96% in 208 patients studied.

Adult↗
PubMed1991

The NMR blood test for cancer: current status.

Our laboratory has developed nuclear magnetic resonance (NMR) techniques for detecting cancer. Using water-suppressed proton (H-1) NMR spectroscopy, we observed that the linewidths of the resonances of methyl and methylene moieties in lipoprotein lipids were consistently narrower in plasma samples from cancer patients than in those from controls. These findings have been corroborated by a number of independent laboratories, but other investigators have been unable to reproduce our results. One reason for the variability of results obtained with H-1 NMR may be that hypertriglyceridemia also induces linewidth narrowing of lipoprotein lipid methyl and methylene resonances, and can cause false positive results. We show that this ambiguity can be circumvented by using a second test based on the carbon-13 (C-13) NMR spectrum of plasma. Here we postulate that the cancer-associated changes seen in H-1 and C-13 NMR spectra are caused by peroxidation of lipoprotein lipids, an effect that may be induced by tumor necrosis factor-alpha released during malignancy.

Biomarkers, Tumor↗
PubMed1990

Nuclear magnetic resonance studies of sodium/calcium exchange in frog perfused, beating hearts.

This study explores the effect of extracellular Ca2+ concentration ([Ca2+]o), on the intracellular Na+ concentration ([Na+]i), in frog intact hearts using nuclear magnetic resonance spectroscopy, which allows for the measurement of [Na+]i in perfused, beating hearts. Decreases in [Ca2+]o yielded marked increases in [Na+]i. A similar effect was seen during inhibition of the Na+/K+ pump and was fully reversible. This sensitivity of [Na+]i to [Ca2+]o, previously observed using microelectrodes, supports a crucial physiological role for Na+/Ca2+ exchange in frog intact, beating hearts.

Animals↗
PubMed1990

Alteration of aliphatic lipid proton NMR linewidths by malignant tumors in guinea pigs.

Water-suppressed proton nuclear magnetic resonance spectroscopy was used to observe plasma lipoprotein lipid methyl and methylene resonances from guinea pigs which had been injected with viable or heat-killed line 1 or line 10 tumor cells or sterile oil. It was shown that the widths of these resonances became significantly sharper as the number of tumor cells grew. Plasma from tumor-free control animals showed no change in the NMR linewidths. It is concluded that the changes observed reflect a specific host response to viable tumor cells, and in these models there is a reciprocal relationship between the number of viable tumor cells and the linewidths of plasma lipoprotein methyl and methylene resonances.

Animals↗
PubMed1990

Measurement of left ventricular mass in rats using electrocardiogram-gated magnetic resonance imaging.

To evaluate the ability of electrocardiogram (ECG)-gated magnetic resonance (MR) imaging to assess in vivo left ventricular (LV) mass in the rat, we studied 20 healthy adult Sprague-Dawley and Fischer 344 rats and 8 additional rats that underwent scanning after induction of volume overload by aortic leaflet disruption. ECG-gated spin-echo pulse sequences were used to acquire a series of 1-mm thick modified short-axis images of the left ventricle. The area enclosed by the endocardial and epicardial borders of the left ventricle was multiplied by the interslice distance and specific gravity of myocardium to obtain calculated slice mass. Total LV mass was obtained by summing the individual slices. The calculated value for LV mass was then compared with the LV mass as determined at postmortem examination. Linear regression analysis showed an excellent correlation of MR-estimated mass (x) with autopsy-measured LV mass (y) (y = 0.90x + 65, r = 0.98). For this method intraobserved and interobserver slice correlations were 0.97 and 0.96, respectively. There was no significant difference in LV mass as determined from a series of diastolic vs. systolic images in a subset of six animals. Over a mean of 6.5 wk of observation, LV mass increased by 40% in the animals subjected to aortic leaflet disruption. These results demonstrate that MR imaging is highly accurate for the non-invasive in vivo assessment of LV mass in the adult rat.

Animals↗
PubMed1979

Effect of the sodium/potassium ratio on glyceraldehyde 3-phosphate dehydrogenase interaction with red cell vesicles.

Binding of glyceraldehyde 3-phosphate to glyceraldehyde-3-phosphate dehydrogenase, the membrane protein known as Band 6, causes shifts in the 31P nuclear magnetic resonance spectrum of the substrate (Fossel, E.T. and Solomon, A.K (1977) Biochim. Biophys. Acta 464, 82--92). We have studied the resonance shifts produced by varying the sodium/potassium ratio, at constant ionic strength, in order to examine the relationship between the cation transport system and glyceraldehyde-3-phosphate dehydrogenase. Alteration of the potassium concentration at the extracellular face of the vesicle affects the conformation of glyceraldehyde-3-phosphate dehydrogenase at the cytoplasmic face, thus showing that a conformation changed induced by a change in extracellular potassium can be transmitted across the membrane. Alterations of the sodium concentration at the cytoplasmic face also affect the enzyme conformation, whereas sodium changes at the extracellular face are without effect. In contrast, there is no sidedness difference in the effect of potassium concentrations. The half-values for these effects are like those for activation of the red cell (Na4 + K+)-ATPase. We have also produced ionic concentration gradients across the vesicle similar to those Glynn and Lew (1970) J. Physiol. London 207, 393--402) found to be effective in running the cation pump backwards to produce adenosine triphosphate in the human red cell. The sodium/potassium concentration dependence of this process in red cells is mimicked by 31P resonance shifts in the (glyceraldehyde 3-phosphate/glyceraldehyde-3-phosphate dehydrogenase/inside out vesicle) system. These experiments provide strong support for the existence of a functional linkage between the membrane (Na+ + K+)-ATPase and the glyceraldehyde-3-phosphate dehydrogenase at the cytoplasmic face.

Adenosine Triphosphate↗
PubMed1978

Ouabain-sensitive interaction between human red cell membrane and glycolytic enzyme complex in cytosol.

Binding of 2,3-diphosphoglycerate to monophosphoglycerate mutase, of which it is an obligatory cofactor, causes changes in the resonance positions of the 31P nuclear magnetic resonance spectra of both phosphate groups. It has previously been shown that these resonances shift when other glycolytic enzymes, such as phosphoglycerate kinase, are added to form the 2,3-diphosphoglycerate . monophosphoglycerate mutase . phosphoglycerate kinase complex. In view of this association, we have examined the set of glycolytic enzymes from aldolase to pyruvate kinase and found evidence of direct communication between all of these enzymes. A multi-enzyme complex of 1--2 . 10(6) daltons has been separated from broken cell ghosts by Biogel column filtration and evidence has been presented to show that this complex exhibits aldolase, glyceraldehyde 3-phosphate dehydrogenase and phosphoglycerate kinase activity. The glycolytic multi-enzyme complex interacts with the outer face of inside-out vesicles prepared from human red cells and the interaction is suppressed by application of 10(-6) M ouabain to the inner face of these vesicles. These studies show that the conformation of the enzymes comprising the megadalton complex are responsive to the application of ouabain to the outer red cell membrane surface.

Cytosol↗
PubMed1978

Interaction of fluorinated ether anesthetics with artificial membranes.

Fluorine-19 nuclear magnetic resonance spectroscopy is applied to the study of the environment of dipalmitoyl phosphatidylcholine-bound fluorinated ether anesthetics (enflurane, fluoroxene and methoxyflurane) both below and above the lipid gel to liquid crystal phase transition temperature. Line widths and spin-lattice relaxation time (T1) measurements are consistent with substantial immobilization of the lipid-bound anesethetic molecules. Heating anesthetic/lipid mixtures above the lipid transition temperature leads to narrowing of the lipid-bound anesthetic fluorine resonances accompanied by little or no change in anesthetic fluorine-19 chemical shifts, suggesting that although the mobility of the bound anesthetic increases at the higher temperature, the nature of the anesthetic-lipid interaction changes little as a result of this phase change. Differential scanning calorimetric studies of the effects of these anesthetics on the phase transition behavior of the phospholipid indicate that the regions of the bilayer in which volatile anesthetics partition at lower concentrations are different from the regions in which they partition at higher concentrations.

Anesthetics↗
PubMed1977

Membrane mediated link between ion transport and metabolism in human red cells.

When 10(-6) M oubain is added to human red cell that have been incubated without glucose for two hours, there is a significant shift in the 31P nuclear magnetic resonances of both phosphate groups of cellular 2,3-diphosphoglycerate, which is not found in control cells incubated with glucose. This means that an effect induced by ouabain on the outside of the red cell membrane is transmitted through the membrane to alter the environment of an intracellular metabolite. Experiments with glycolytic cycle inhibitors have indicated that the intracellular ligand responsible for the resonance shifts is monophosphoglycerate mutase which requires 2,3-diphosphoglycerate as a cofactor for the reaction it catalyzes. To account for this finding a hypothesis is presented that the (Na+ + K+)-ATPase in human red cells is linked to monophosphoglycerate mutase through the agency of phosphoglycerate kinase. Evidence is presented for the existence of phosphoglycerate kinase/monophosphoglycerate mutase in solution. It is shown that this complex can interact with the cytoplasmic face of (Na+ + K+)-ATPase at the outside surface of inside out red cell vesicles, and that this interaction is inhibited when 10(-6) M ouabain is contained within the vesicle. Neither monophosphoglycerate mutase nor phosphoglycerate kinase is significantly bound to the inside surface of the intact human red cell, but glyceraldehyde 3-phosphate dehydrogenase is; it is shown that this enzyme also interacts with the cytoplasmic face of the (Na+ + K+)-ATPase and that the interaction is inhibited by 10(-6) M ouabain.

Biological Transport, Active↗
PubMed1976

Modulation of 2,3-diphosphoglycerate 31P-NMR resonance positions by red cell membrane shape.

Na+ transport in the red cells of the dog is dependent on cell volume, a 20% change in cell volume leading to a 25-fold increase in apparent Na+ flux; the effect is dependent upon metabolic energy. We have found that swelling and shrinking dog red cells causes a shift in the 31P-NMR peak of 2,3-diphosphoglycerate, which is present in dog red cells at 5.5 mM. Control experiments indicate that the 2,3-diphosphoglycerate resonance peak shifts may not be attributed to: interaction with hemoglobin, changes in cell pH, ionic strength, diamagnetic susceptibility or small changes in the Mg2+/2,3-diphosphoglycerate ratio. Experiments with chlorpromazine and pentanol which alter red cell membrane area by a mechanism different from osmotic swelling suggest that 2,3-diphosphoglycerate interacts with a binding site in the cell that is dependent upon the physical condition of the dog red cell membrane.

Animals↗