Cardiac transplants in Virginia: progress report.
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Forecasting↗
Biomedical subjects
J A Thompson
Publications and source records attributed to J A Thompson.
Role of 5-HT2 receptor inhibition in pulmonary embolization.
We examined the role of serotonin at the 5-HT2 receptor site after pulmonary embolization for changes in hemodynamics, gas exchange, and lung water. Pulmonary embolization was induced using 0.75 gm/kg autologous clot in anesthetized artificially ventilated dogs. Pulmonary vascular resistance rose by 5 min from 3.4 +/- 1.5 to 14.2 +/- 2.1 mm Hg/liter/min (p less than 0.001), arterial oxygenation decreased from 91 +/- 5 to 68 +/- 5 mm Hg (p less than 0.01), platelet count decreased from 201 +/- 64 to 141 +/- 32 ml X 10(3), and the wet to dry weight lung ratio increased from 2.59 +/- 0.34 to 4.21 +/- 0.21 (p less than 0.001). Inhibition by ketanserin, a selective serotonergic inhibitor at the 5-HT2 receptor site substantially attenuated the increase in pulmonary vascular resistance from 3.6 +/- 1.4 to 8.0 +/- 2.5 mm Hg/liter/min, ablated the hypoxemia and platelet reduction and inhibited the formation of pulmonary edema. Infusion of serotonin simulated only some of the above changes as the pulmonary vascular resistance increased from 3.16 +/- 1.6 to 13.5 +/- 4.1 mm Hg/liter/min (P less than 0.01) and the oxygenation decreased from 96 +/- 5 to 57 +/- 4 mm Hg (P less than 0.01). Serotonin infusion, however, did not cause pulmonary edema. The administration of ketanserin ablated the increase in pulmonary vascular resistance and the hypoxemia following serotonin infusion. We conclude that following pulmonary embolization, serotonin at the 5-HT2 receptor is responsible for the fall in PaO2 and partially responsible for the increased pulmonary vascular resistance. Although ketanserin inhibits the formation of pulmonary edema following pulmonary embolization, serotonin does not seem to be directly responsible.
Animals↗
Interaction of cytochrome P-450 with a hydroperoxide derived from butylated hydroxytoluene. Mechanism of isomerization.
Attack of O2 on the phenoxy radical derived from butylated hydroxytoluene resulted in the formation of 2,6-di-t-butyl-4-hydroperoxy-4-methyl-2,5-cyclohexadienone (BOOH). This hydroperoxide was rapidly consumed when incubated with rat liver microsomes in the absence of NADPH. The destruction of BOOH was accompanied by formation of the corresponding alcohol (BOH) and a derivative of the alcohol (B(OH)2) in which a t-butyl methyl group was hydroxylated. This diol was produced also when BOH was incubated with microsomes and NADPH, but at a slower rate. Mass spectral analyses of B(OH)2 formed from substrates labeled with either 2H or 18O, showed that oxygen was transferred from the peroxy group to a t-butyl group (via the heme iron of P-450) without migration of the intermediate alcohol from the enzyme active site. The results support a mechanism involving heterolytic O-O bond cleavage during isomerization of the hydroperoxide to B(OH)2. The chiral diol was produced from BOOH nonstereoselectively, but the NADPH/O2-supported hydroxylation of BOH resulted in the formation of a 20% excess of one enantiomer of B(OH)2. Analyses of products formed from the interaction of cumene hydroperoxide with cytochrome P-450 showed that this substrate undergoes rearrangement also; 2-phenyl-1,2-propanediol was produced, together with cumyl alcohol and acetophenone. These results indicate that isomerization competes with other pathways of hydroperoxide destruction by cytochrome P-450.
Animals↗
Isolation and analysis of N-oxide metabolites of tertiary amines: quantitation of nicotine-1'-N-oxide formation in mice.
To investigate the formation and elimination of nicotine-1'-N-oxide (NNO) in mice treated with a single injection of nicotine, sensitive and selective methods were developed to quantitate this polar and heat-labile metabolite. The compound was isolated from tissue homogenates as a dodecyl sulfate ion pair with C18 extraction cartridges and analyzed on an amino bonded-phase high-performance liquid chromatographic column with a mobile phase consisting of isopropanol-water. Overall recoveries of NNO were 64-76% from biological media. Several methods of detection were evaluated; radiolabeling was necessary to achieve the sensitivity required for pharmacokinetic studies in mice. The cis and trans isomers of NNO were separated on a Partisil PAC column and enzymatic selectivity was evaluated for the formation of these isomers in mice.
Animals↗
Polymorphic ventricular tachycardia and ventricular fibrillation due to N-acetyl procainamide.
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Acecainide↗
Dynamic headspace analysis of volatile metabolites from the reductive dehalogenation of trichloro- and tetrachloroethanes by hepatic microsomes.
A dynamic headspace technique was developed to facilitate the identification and quantitation of low levels of volatile metabolites produced in vitro by subcellular preparations. The method is complementary to commonly used static headspace and solvent-extraction techniques, and involves purging the compounds from microsomal suspensions with an inert gas, trapping them on a short column of adsorbant resin, and transferring the metabolites to a gas chromatograph. An apparatus was designed to facilitate the incubations and isolations of volatile compounds. Recoveries of several chlorinated hydrocarbons with boiling points in the range 12 to 186 degrees C were 85% or higher, and the recovery of vinyl chloride (boiling point -13 degrees C) was 25%. The quantitative precision of the method was determined and calibration curves were established for each metabolite, demonstrating that no discrimination occurred over a wide range of concentrations. This technique was employed to investigate the reductive metabolism of 1,1,1-trichloroethane, 1,1,2-trichloroethane, and 1,1,2,2-tetrachloroethane by rat liver microsomes. The metabolites from these substrates were 1,1-dichloroethane, vinyl chloride, and 1,2-dichloroethylene, respectively. These conversions were NADPH-dependent, occurred only under anaerobic conditions, and indicate that chloroethanes with relatively low electron affinities can be reduced slowly by microsomal cytochrome P-450. The rates of formation of vinyl chloride, 1,1-dichloroethane, and 1,2-dichloroethylene with 1.0 mM substrate were 12.5 +/- 2.0, 122 +/- 14, and 147 +/- 12 pmol/min/mg of protein, respectively. The results show that there are distinct advantages of the purge/trap method over the static headspace method for studying volatile metabolites when high sensitivity is required.
Animals↗
Therapy for painful cutaneous leiomyomas.
Cutaneous leiomyomas, if multiple and painful, can pose a treatment dilemma. The types of cutaneous leiomyomas and the anatomy and physiology of smooth muscle are reviewed as an introduction to the therapy of painful leiomyomas by a calcium-channel blocker.
Adult↗
Interleukin 2 (IL 2) administered in vivo: influence of IL 2 route and timing on T cell growth.
The influence of the route and the frequency of IL 2 administration on the ability of IL 2 to induce the growth of activated T cells in vivo was evaluated. Initial pharmacokinetic studies confirmed that i.v. injection of IL 2 results in a relatively high peak serum concentration, but a short serum half-life. By contrast, i.p. or subcutaneous (s.c.) injection of IL 2 results in a lower peak concentration but a prolonged serum half-life. The bioavailability of IL 2 administered by these routes was assessed by measuring the in vivo growth of adoptively transferred T cells that had been previously cultured long-term with IL 2, because the growth of such cells in vivo has been shown to be proportional to the dose of IL 2 administered. The results demonstrated that i.p., s.c., or i.v. administration of IL 2 each resulted in marked donor T cell growth in vivo. Thus, IL 2 can function in vivo at sites distant to the sites of injection. In addition, the magnitude of T cell growth in vivo varied dependent on the route of IL 2 administration and correlated with the length of time IL 2 was detectable in serum, rather than the peak level achieved (i.e., IL 2 inoculated i.v. had the highest peak concentration but was least effective). As suggested by these findings, dividing the total dose of IL 2 into frequent low-dose injections was more effective in inducing T cell growth in vivo than was dividing the total dose of IL 2 into less frequent higher-dose injections. These studies confirm the great potential for IL 2 to induce the growth of activated of T cells in vivo and demonstrate that the rate of T cell growth reflects not only the dose but also the route and timing of IL 2 administration.
Animals↗
Effect of prazosin on the efflux of 3H-norepinephrine and metabolites from the intima and adventitia of the rabbit ear artery.
The spontaneous and stimulation-induced (SI) effluxes of 3H-norepinephrine (3H-NE) and its metabolites from the intimal and adventitial surfaces of perfused segments of rabbit ear arteries were determined; vessels were previously incubated with 3H-NE (0.6 microM). The total SI adventitial efflux of 3H was approximately 10-fold greater than the intimal efflux, contained a higher percentage of unchanged 3H-NE (48 vs. 12%) and a lower percentage of O-methylated metabolites (17 vs. 55%); there was little difference between the percentages of deaminated catechols (35 vs. 31%). Prazosin, at a concentration (0.24 microM) which prevented the arteries constricting during stimulation, had little effect on the composition of the SI effluxes; however, it caused 2- to 3-fold increases in the effluxes of 3H-NE and its metabolites into the lumen during the period of stimulation. This effect is attributed to the failure of the vessel wall to thicken during stimulation, thus facilitating diffusion of 3H-NE and its intraneuronally formed metabolites across the media. Prazosin decreased the percentage of unchanged 3H-NE and increased that of the deaminated catechols in the spontaneous efflux; these effects are attributed to a direct effect of prazosin on the intra-neuronal metabolism of 3H-NE.
Animals↗
Intravenous calcium treatment of refractory hypotension in Reye's syndrome.
Hypotension refractory to volume infusion and sympathomimetic drugs developed in a child with Reye's syndrome who had received prochlorperazine prior to admission. Calcium chloride given intravenously restored autonomic tone, resulting in restoration of a normal BP and cerebral perfusion pressure. Calcium may reverse the hypotensive effects of prochlorperazine maleate and may help reverse hypotension in patients with Reye's syndrome who have been pretreated with phenothiazine antiemetics.
Calcium Chloride↗
Reductive metabolism of 1,1,1,2-tetrachloroethane and related chloroethanes by rat liver microsomes.
The susceptibility of polychlorinated ethanes to reductive metabolism was evaluated by measuring the amount of each compound consumed during anaerobic incubations with rat live microsomes; 1,1,1,2-tetrachloroethane, pentachloroethane and hexachloroethane were metabolized extensively, 1,1,1,2-tetrachloroethane and the trichloroethanes were metabolized very slowly and the dichloroethanes were not metabolized at a detectable rate. The electron affinity of the chloroethanes was determined by measuring electrochemical half-wave reduction potentials. Chloroethanes with an E1/2 of - 1.35 V or less negative were reduced readily in microsomes while those with an E1/2 equal to or more negative than -1.90 V were not good substrates for enzymatic reduction. Metabolites produced from 1,1,1,2-tetrachloroethane in vitro were 1,1-dichloroethylene (DCE) and 1,1,2-trichloroethane (TCEA) and the ratio DCE/TCEA was about 25:1. These conversions were NADPH-dependent and were inhibited by air, CO and metyrapone. In the presence of SKF 525-A, DCE formation was inhibited by 47%. Microsomes from untreated or beta-naphthoflavone-treated rats were 70-90% less active than microsomes from phenobarbital-treated rats. The Km was 0.50 mM and the Vmax was 66 nmol min-1 mg-1 protein for DCE formation. The results are consistent with the proposal that 1,1,1,2-tetrachloroethane is reduced by hepatic cytochrome(s) P-450 to a free radical intermediate which, for the most part, remains closely associated with the enzyme, is reduced further and undergoes beta-elimination of a chloride ion to form DCE. The occurrence of this reductive pathway in vivo was demonstrated by the quantitation of DCE and TCEA in blood from rats treated with 1,1,1,2-tetrachloroethane.
Anaerobiosis↗
Interleukin-2 administered in vivo induces the growth and augments the function of cultured T cells in vivo.
The purpose of the studies being described was to determine if interleukin-2 (IL-2) administered in vivo can induce the growth and increase the number of antigen-activated T cells, and thereby augment specific T cell function in vivo. Initial experiments examined the in vivo growth of adoptively transferred T cells previously cultured long term with IL-2, since in vitro such long-term cultured T cells are exquisitely dependent on exogenous IL-2 for proliferation and survival. To identify and quantify donor T cells in vivo, experiments were performed with donor and host mice congenic for the T cell marker Thy 1. Host mice receiving congenic long-term cultured immune T cells were inoculated daily with purified IL-2 beginning on the day of cell transfer, and donor T cells within host ascites, spleen, and lymph nodes were enumerated at selected points in time. The experiments demonstrated that exogenous IL-2 induced in vivo growth of long-term cultured T cells proportional to the dose of IL-2 administered. Similar IL-2 regimens induced the in vivo growth and augmented the function of donor T cells that had been activated to express IL-2 receptors in vitro by 5-day culture with antigen but had not been cultured with exogenous IL-2. Thus, prior adaptation to growth with exogenous IL-2 in vitro is not necessary to render T cells responsive to IL-2 in vivo. In contrast to long-term cultured T cells in vivo (which died rapidly in vivo without exogenous IL-2), noncultured donor T cells proliferated in vivo in response to antigen.(ABSTRACT TRUNCATED AT 250 WORDS)
Animals↗
Differences in the ultrastructural localization of carcinoembryonic antigen in human breast and in colon tumour cells.
The ultrastructural localization of carcinoembryonic antigen (CEA) has been compared in human breast and in human colon tumour cells, utilising immunohistological methods at the electron microscope level. Colon tumours (cell line LS 174 T, and xenografted human colon tumours in nude mice) are characterized by a strong CEA-positivity attached to the outer cell membrane. In contrast, mammary carcinomas (bioptically prepared solid tumours) showed to extracellular membrane - bound labelling. In these tumours, extracellular CEA-localization was mainly found on electron dense bodies.
Animals↗
Interleukin 2 administered in vivo induces the growth of cultured T cells in vivo.
The capacity of exogenous IL 2 to induce the growth of antigen-activated T lymphocytes in vivo was evaluated. The in vivo growth of adoptively transferred T lymphocytes that had been previously cultured long-term with IL 2 was initially examined, because in vitro such T cells are exquisitely dependent upon exogenous IL 2 for proliferation and survival. Daily administration of IL 2 in vivo, beginning on the day of cell transfer, induced these IL 2-dependent long-term cultured T lymphocytes to proliferate in vivo, and the magnitude of in vivo growth was proportional to the dose of IL 2 administered. The capacity of IL 2 to induce the in vivo growth of antigen-activated T cells not previously exposed in vitro to exogenous IL 2 was similarly studied. T lymphocytes from the spleens of immune mice, activated by 5-day culture with tumor antigen before transfer, survived poorly in vivo when injected with antigen alone, but demonstrated marked proliferation in vivo in response to antigen and exogenous IL 2. By contrast, immune spleen cells transferred with antigen, but without prior culture, proliferated without supplementary exogenous IL 2. Moreover, the growth of noncultured donor T cells was not augmented by the administration of exogenous IL 2, implying that noncultured spleen cells immune to tumor antigens can produce sufficient amounts of endogenous IL 2 in vivo to sustain maximal T cell growth over the time period examined. Importantly, the ability of exogenous IL 2 to induce donor T cell growth in vivo correlated with its ability to function in vivo to augment the anti-tumor efficacy of specifically immune donor T cells in models for the adoptive therapy of disseminated antigenic murine leukemia. Thus, the current studies highlight the potential of exogenous IL 2 to induce T cell growth in vivo and suggest that the administration of IL 2 in vivo may be useful for augmenting T cell responses that are relatively deficient in the production of endogenous IL 2.
Animals↗
Protease nexins: cell-secreted proteins that mediate the binding, internalization, and degradation of regulatory serine proteases.
The protease nexins (PN-I, Mr approximately 38,000; PN-II, Mr approximately 95,000; and PN-III, Mr approximately 31,000) are recently described cell-secreted proteins that selectively link to regulatory serine proteases in the extracellular environment and mediate their cellular binding, internalization, and degradation. In the present studies we compared the protease nexins with respect to protease specificity, heparin sensitivity, and general mode of action. By competitive binding assays using [125I]-thrombin, [125I]-nerve growth factor-gamma (125I-NGF-gamma), and [125I]-epidermal growth factor binding protein (125I-EGF-binding protein), we characterized the nexins in terms of protease specificity and determined that PN-I links to and mediates the cellular binding of thrombin or urokinase, whereas PN-II and PN-III preferentially link to and mediate the cellular binding of the EGF binding protein and NGF-gamma, respectively. In addition, whereas the ability of PN-I to link to thrombin is strongly modulated by heparin, PN-II and PN-III are essentially unaffected by heparin. The linkage of each of the nexins to their respective proteases requires the catalytic site serine of the protease, judged by the inability of diisopropylphospho (DIP) derivatives of the proteases tested to link to their respective nexins. Subsequent to linkage, the nexin:protease complexes are bound to cells, rapidly internalized, and ultimately degraded via a monensin-sensitive apparently lysosomal pathway, although each nexin:protease complex is degraded at its own characteristic rate. Importantly, the protease nexins provide the major pathway through which human fibroblasts interact with each of the serine proteases studied. Taken together, these data suggest that the nexins are a unique class of cell-secreted proteins that enable cells to monitor and selectively regulate specific serine proteases in their environment.
Amyloid beta-Protein Precursor↗
Purification of nucleic acids by RPC-5 ANALOG chromatography: peristaltic and gravity-flow applications.
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Animals↗
The time-course development of the effects of ethanol ingestion on choline oxidase.
Male rats were fed a low-fat diet containing 36% of calories as ethanol, and the time-course development of the effects of ethanol on liver mitochondrial oxidation of choline was determined. Ethanol induced an increase in choline oxidase at days 2, 5 and 7 after being introduced into the diet. Due to an observed 32% increase in total fatty acids in the whole liver, defatted bovine serum albumin was added to the buffer used to homogenize the liver. The presence of bovine serum albumin resulted in a significant decrease in choline oxidase activity at days 2 and 5; however, ethanol still induced an increase in choline oxidase activity in these mitochondria. The total fatty acid concentration of mitochondria prepared in the absence of bovine serum albumin increased steadily until day 5; however, by day 7 the fatty acid concentration had returned to control levels. The addition of bovine serum albumin to the homogenization medium prevented the increase in the total amount of fatty acids. The fatty acid composition of the bovine serum albumin-treated mitochondria, however, was not different from the mitochondria isolated in the absence of bovine serum albumin. Further, the addition of a free fatty acid to isolated mitochondrial preparations caused about a 100% increase in choline oxidase. These data are consistent with the idea that choline oxidase may be regulated to some extent by an influx or an increase in free fatty acids in the liver as a result of ethanol ingestion. Thus, a second mechanism has been described which contributes to the increase in choline oxidase after ethanol ingestion.
Alcohol Oxidoreductases↗
Analyses of nicotine and cotinine in tissues by capillary gas chromatography and gas chromatography-mass spectrometry.
Selective extraction and chromatographic techniques have been developed to measure low nanogram quantities of nicotine and cotinine in tissues. Analyses were performed by capillary column gas chromatography with a specific nitrogen-phosphorus detector and by gas chromatography-mass spectrometry. With close structural analogues for internal standards, high quantitative accuracy and precision were demonstrated for the range 5-1000 ng per g of tissue. The sensitivity limit was 2-3 ng/g for both compounds. The advantage of these techniques compared to previously published methods is increased selectivity; the other methods were developed for analysis of biological fluids and are not readily adaptable to more complex biological matrices such as tissue homogenates. With the newly developed techniques, we were able to perform a pharmacokinetic study of nicotine and cotinine in mouse liver following a single intraperitoneal injection of nicotine.
Animals↗