Search PubMed⌕ Search

Biomedical subjects

L Levine

Publications and source records attributed to L Levine.

At least 217 records · Page 12Linked to original sources
PubMed1979

Immunoassay of indomethacin: the use of [125I] protein A to detect specific serologic binding.

The sera of rabbits that were injected with indomethacin covalently linked to human albumin bound increasing amounts of [14C] indomethacin during the course of immunization. The serum-binding components chromatographed with the gamma-globulin fraction and were precipitated with goat-anti-rabbit-gamma-globulin. When measured by radioimmunoassay with [14C] indomethacin under optimal conditions, 34 ng (95 pmoles) of unlabeled indomethacin inhibited [14C] indomethacin binding 50%. The antibodies reacted most effectively with indomethacin and the desmethylated analogue, 1-(p-chlorobenzoyl)-2-methyl-5-hydroxyindole-3-acetic acid, but not 2-methyl-5-methoxy-indole-3-acetic acid. An immunoassay based on the use of [125I] Protein A as tracer for IgG antibody was developed for quantitative determination of indomethacin at the picogram level. Indomethacin, immobilized by covalent linkaae to a solid support, bound the rabbit anti-indomethacin. Protein A, labeled with [125I], measured the levels of the bound IgG antibody. Fluid phase indomethacin competed with solid-phase indomethacin for the anti-indomethacin, which resulted in decreased anti-indomethacin and consequently decreased [125I] Protein A on the immobilized indomethacin-anti-indomethacin complex. The serologic specificity with the immobilized ligand immunoassay was the same as that found with the [14C] indomethacin radioimmunoassay, but the sensitivity for detection of indomethacin was increased over 300-fold.

Animals↗
PubMed1979

The use of immobilized ligands and [125I]protein a for immunoassays of thromboxane B2, prostaglandin D2, 13,14-dihydro-prostaglandin E2, 5,6-dihydro-prostaglandin I2, 6-keto-prostaglandin F1 alpha, 15-hydroxy-9 alpha, 11 alpha(epoxymethano)prosta-5,13-dienoic acid and 15-hydroxy-11 alpha,9 alpha(epoxymethano)prosta-5,13-dienoic acid.

Immunoassays were developed for quantitative determination of thromboxane B2, prostaglandin D2, 13,14-dihydro-prostaglandin E2, 5,6-dihydro-prostaglandin I2, 6-keto-prostaglandin F1 alpha, 15-hydroxy-9 alpha, 11 alpha (epoxymethano) prosta-5, 13-dienoic acid and 15-hydroxy-11 alpha, 9 alpha (epoxymethano) prosta-5,13-dienoic acid. Ligands immobilized by covalent linkage to a solid support, bound homologous rabbit antibodies. [125I] Protein A was used to measure the bound IgG antibody. Increments of homologous and heterologous fluid-phase ligand completed with solid-phase ligand for antibody and resulted in decreasing amounts of bound [125I]-Protein A. The serologic specificity for each immune system was determined. Immunoassays for thromboxane B2, 6-keto-prostaglandin F1 alpha, and 5,6-dihydro-prostaglandin I2 were used to identify their respective homologous ligands that were separated by normal phase and reversed phase high pressure liquid chromatography.

15-Hydroxy-11 alpha,9 alpha-(epoxymethano)prosta-5↗
PubMed1979

Prostaglandins E2, F2 alpha, 6-keto-F1 alpha and thromboxane B2 levels in carrageenin-induced inflammatory exudates in the rat air-pouch granuloma.

Levels of PGE2, PGF2 alpha, PGI2 (measured as 6-keto-PGF1 alpha), and thromboxane B2 were determined in rat inflammatory excuates induced 1, 3, and 7 days after carrageenin injection into air-pouch granuloma. The PGE2 and 6-keto-PGF1 alpha levels found in the exudate could not account for the differences in PGE2-like activity as measured by biologic and serologic methods.

6-Ketoprostaglandin F1 alpha↗
PubMed1979

Arachidonic acid metabolism by cells in culture: analyses of culture fluids for cyclooxygenase products by radioimmunoassay before and after separation by high pressure liquid chromatography.

Biosynthesis of PGI2, measured as 6-keto-PGF1 alpha, thromboxane A2, measured as thromboxine B2, and prostaglandins E2, F2 alpha and D2 by lymphocytes (WEHI-5), endothelial cells, normal human lung cells (WI-38), normal human fibroblasts (D-550), rat adult Type II alveolar cells (L-2) and canine kidney cells (MDCK) was measured by radioimmunoassay of culture fluids before and after their separation by high pressure liquid chromatography. The metabolic profiles and the levels of each metabolite obtained by both procedures were comparable. The profile of arachidonic biosynthesis was unique to each cell. Endothelial cells synthesized primarily prostacyclin; the lymphocytes synthesized principally thromboxane. The dog kidney cells synthesized relatively large amounts of prostaglandin F2 alpha, I2 and E2, while the normal human lung cells produced predominantly prostaglandins E2, F2 alpha, and thromboxane. The rat adult alveolar cell (L-2) and the normal human fibroblasts (D-550) biosynthesized primarily prostaglandins E2 and F2 alpha.

Animals↗
PubMed1979

Alpha- and beta-adrenergic stimulation of arachidonic acid metabolism in cells in culture.

Madin-Darby canine kidney cells (MDCK) synthesize prostaglandin (PG) F(2alpha), PGI(2) (measured as 6-keto-PGE(1alpha)), PGE(2), PGD(2), and thromboxane A(2) (measured as thromboxane B(2)). When incubated in the presence of norepinephrine (6 muM), the syntheses of these arachidonic acid metabolites are stimulated 3-fold. Norepinephrine's effect can be antagonized by the addition of alpha-adrenergic receptor blocking agents (phenoxybenzamine>phentolamine>yohimbine>dibenamine>tolazoline) but not by the beta-adrenergic blocking drug propranolol. Norepinephrine's stimulation is also inhibited by low concentrations of dihydroergotamine, bromocryptine, ergocryptine, and ergotamine. The stimulation of PG synthesis by norepinephrine is reversible, continues during the 24 hr of incubation, and requires the presence of norepinephrine at the receptor site but it is not blocked by the addition of colchicine, cytochalasin B, or cycloheximide. Neither phenoxybenzamine nor ergotamine at concentrations that block norepinephrine's stimulation of PG biosynthesis suppresses the increase in PG synthesis induced by exogenous arachidonic acid, suggesting that the alpha-adrenergic regulation is not occurring primarily at the cyclooxygenase step in the metabolism of arachidonic acid. In mouse lymphoma cells (WEHI-5), low concentrations of isoproterenol or norepinephrine stimulate the synthesis of thromboxane, an effect that can be blocked by the addition of propranolol but not by relatively high concentrations of phenoxybenzamine or ergotamine. Taken together, these results suggest that alpha-adrenergic receptor stimulation promotes the deacylation of phospholipids by MDCK cells whereas beta-adrenergic mechanisms lead to activation of similar pathways in WEHI-5 cells.

Adrenergic alpha-Antagonists↗
PubMed1979

Evidence for selection by male mating success in natural populations of Drosophila pseudoobscura.

Gene arrangement frequencies were determined at two stages in the life history of Drosophila pseudoobscura taken from nature. Three populations in the central highlands of Mexico were each sampled twice during 1976. Gene arrangement frequencies were measured in adult males and in larvae that were the offspring of females collected at the same time. The adult males were in all likelihood a representative sample of those who fathered the larvae produced by the wild females. Differences in gene arrangement frequency between these two life stages should indicate the operation of natural selection. One-third of our comparisons of common gene arrangement frequencies in males and in larvae from the next generation were statistically significant, as were one-third of our comparisons of total frequency arrays in the two life stages. We consider the components of selection that could produce such frequency changes and reason that male mating success must be the major one. Gene arrangement frequencies in the Mexican populations fluctuate within wide bounds. Selection must act to retain the polymorphism in the face of this flux in gene arrangement frequencies, and we suggest that male mating success plays an important role.

Animals↗
PubMed1978

Stimulation of prostaglandin synthesis by tumor-promoting phorbol-12, 13-diesters in canine kidney (MDCK) cells. Cycloheximide inhibits the stimulated prostaglandin synthesis, deacylation of lipids, and morphological changes.

Tumor-promoting 12-O-tetradecanoyl-phorbol-13-acetate and phorbol-12, 13-di-decanoate, but not the non-tumor-promoting 4alpha-phorbol-12, 13-di-decanoate, stimulated deacylation of cellular lipids, prostaglandin biosynthesis, and morphological changes in cultured MDCK cells. The increased prostaglandin biosynthesis and morphological changes required at least 24 h for expression. Cycloheximide inhibited the stimulated prostaglandin biosynthesis, the changes in morphology, and the increased lipid deacylation, but hydrocortisone (1.0 microgram/ml) did not. Indomethacin (0.5 microgram/ml) completely inhibited the stimulated prostaglandin biosynthesis and also inhibited some deacylation of cellular lipids. Indomethacin, however, did not effect the 12-O-tetradecanoyl-phorbol-13-acetate-stimulated changes in morphology.

Cell Line↗
PubMed1978

Plasma prostaglandin metabolites in human labor.

To elucidate the role of prostaglandins in initiating uterine contractions we studied the concentrations of 13,14-dihydro-15-keto-PGE2 (PGE2-M) and 13,14-dihydro-15-keto-PGF2alpha (PGF2alpha-M) in peripheral plasma of pregnant patients. The concentrations of PGE2-M and PGF2alpha-M in pregnant patients at term not in labor were not significantly different from those at midpregnancy. Induction of labor at term pregnancy caused a significant rise of both PGE2-M and PGF2alpha-M. During spontaneous labor there were no significant minute-to-minute fluctuations of plasma PGE2-M and PGF2alpha-M and their concentrations were not different from those at oxytocin-induced labor. Initiation of uterine contractions and abortion at midpregnancy by the intra-amniotic infusion of hypertonic saline was not associated with any change in PGE2-M concentration and a rise in PGF2alpha-M was noted in only one of five patients. The vaginal administration of PGE2 and the intra-amniotic infusion of PGF2alpha were associated in each case with a significant rise of both prostaglandin metabolites. It is concluded that the rise of prostaglandin metabolites in peripheral plasma is secondary to the initiation of uterine contractions at term pregnancy. Such a rise is not usually observed after the initiation of uterine contractions by hypertonic saline at midpregnancy.

Abortion, Induced↗
PubMed1978

Acute phase reactants ceruloplasmin and haptoglobin and their relationship to plasma prostaglandins in rabbits bearing the VS2 carcinoma.

Results of previous studies have shown that the VX2 carcinoma in rabbits synthesizes large amounts of prostaglandin E2 (PGE2). PGE2 secreted by the tumor is rapidly metabolized and can be measured in plasma as the metabolite 13,14-dihydro-15-keto-PGE2 (PGE2-M). We have previously proposed that the hypercalcemia that occurs in rabbits bearing the VX2 carcinoma is due to excessive secretion of PGE2 by the tumor and its subsequent action on the skeleton as a bone resorption-stimulating factor. In the course of these studies, we noted that the plasma of rabbits bearing the VS2 carcinoma became blue about 1 wk after tumor implantation. The intensity of the color increased markedly thereafter. We therefore measured ceruloplasmin in plasma by both chemical and immunological assay methods. Plasma ceruloplasmin and PGE2-M rose in parallel (within 7-10 days) and preceded by 7-10 days the development of hypercalcemia. 2 wk after tumor implantation, plasma PGE2-M and ceruloplasmin had risen about 20- and 6-fold, respectively, while the rise in plasma calcium was just beginning. Indomethacin, an inhibitor of prostaglandin synthesis, given from the time of tumor implantation prevented completely the hypercalcemia and largely inhibited the rise in ceruloplasmin. When given after hyperprostaglandinemia had developed, indomethacin produced a fall in both PGE2-M and ceruloplasmin. A rise in plasma haptoglobin concentrations similar to that seen for ceruloplasmin was also observed. No changes in plasma albumin concentrations occurred. We conclude that the acute phase reactants ceruloplasmin and haptoglobin rise rapidly in the plasma of rabbits bearing the VX2 carcinoma, and that this increase is related to arachidonic acid metabolism in these animals. It is possible that arachidonic acid metabolites also play a role in the elevations of these two plasma proteins observed in certain patients with malignant tumors.

Animals↗
PubMed1978

Stimulation of prostaglandin production in bone by phorbol diesters and melittin.

The production of prostaglandin E2 (PGE2) and bone resorption were studied in neonatal mouse calvaria in organ culture. Two tumor promoters 12-O-tetradecanoyl-phorbol-13-acetate (TPA) and phorbol-12, 13-di-decanoate, but not the non-tumor promoters 4alpha-phorbol-12,13-didecanoate and phorbol, stimulated both PGE2 synthesis in bone and bone resorption. The effect of TPA was maximum at about 25 ng/ml, and half-maximum stimulation occurred at about 8 ng/ml TPA. The effects of TPA on the production of PGE2 and bone resorption were inhibited completely by indomethacin (5.6 X 10(-8) to 5.6 X 10(-7) M). The been venom toxin, melittin, was also a potent stimulator of prostaglandin synthesis in bone and bone resorption. The effect of melittin was maximum at about 25 ng/ml, and the dose-response curve was biphasic. The effects of melittin on the production of PGE2 and bone resorption were also inhbited by indomethacin. Indomethacin did not inhibit the bone resorption-stimulating activity of exogenously added PGE2. We conclude that phorbol diesters, which have irritant and tumor-promoting activity in mouse skin, and the polypeptide melittin can act directly on bone to stimulate resorption by a mechanism involving the local production of PGE2 or possible other indomethacin-inhibited metabolites odonic acid.

Animals↗
PubMed1978

Tumor promoting phorbol diesters stimulate release of radioactivity from [3H]-arachidonic acid labeled- but not [14C]linoleic acid labeled-cells. Indomethacin inhibits the stimulated release from [3H] arachidonate labeled cells.

The tumor promoting phorbol diester, 12-O-tetradecanoyl-phorbol-13-acetate, stimulates MDCK cells to deacylate cellular phospholipids and to produce prostaglandins when measured as the release of arachidonic acid and its metabolites into the culture fluid. Indomethacin, at levels of 2.8 x 10(-8) to 2.8 x 10(-6) M, inhibits the release of radioactivity from [3H]arachidonate labeled cells stimulated by 12-O-tetradecanoyl-phorbol-13-acetate treatment in a concentration dependent manner. At these concentrations, the conversion of released [3H]arachidonic acid into prostaglandins E2 and F2alpha and the production of PGE2 measured serologically also is suppressed in a concentration dependent manner. Indomethacin, at these levels, has no effect on the acylation of [3H]arachidonic acid into cellular lipids. The tumor promoting phorbol diester does not stimulate the release of radioactive materials from MDCK cells labeled with [14C]linoleic acid, although prostaglandin production by these cells is stimulated.

Animals↗
PubMed1978

Adriamycin stimulates canine kidney (MDCK) cells to deacylate cellular lipids and to produce prostaglandins.

Dog kidney (MDCK) cells treated with adriamycin (0.5 micrograms/ml) for 1 hr, produced from 2 to 7 times more prostaglandins E2 and F2alpha when measured in culture media 24, 48 and 72 hrs after the treatment. Indomethacin (ID50 less than 2 x 10(-8) M) and cycloheximide (0.5 micrograms/ml) inhibited this adriamycin-stimulated prostaglandin production. The aglycone of adriamycin (0.5 to 5.0 micrograms/ml) had little stimulating effect. Treatment of [3H]arachidonic acid-labeled MDCK cells with adriamycin (0.5 micrograms/ml) for 1 hr also stimulated deacylation of cellular lipids during subsequent incubation. Altered morphology of MDCK cells resulted from such treatment with adriamycin; indomethacin did not inhibit this change, but cycloheximide did.

Animals↗