Showing papers by "Research Triangle Park published in 1979"

Validation and characterization of the L5178Y/TK+/- mouse lymphoma mutagen assay system.

Abstract: The current status of the L5178Y/TK+/- leads to TK-/- mouse-lymphoma mutagenicity assay is described. Dose-survival-mutagenic response data are shown for 43 chemicals. Mutagenicity and cytotoxicity in the presence or absence of non-induced and/or Aroclor-induced rat-liver S-9 are compared for most of these chemicals, 25 of these for which usuable carcinogenicity data exist have been used to construct an approximately linear relationship between oncogenic potency in vivo and mutagenic potency in this system in vitro; linearity between these two endpoints extends over a greater than 100,000-fold range in potencies. Several carcinogens which are negative or difficult to detect in the standard Ames assay are mutagenic in this mammalian cell system. These include natulan, sodium saccharin (lot S-1022), p,p'-DDE (metabolite of DDT), dimethylnitrosamine, diethylnitrosamine and diethylstilbestrol. Characterization of the TK-/- mutants suggests that two mutagenic mechanisms contribute to their final yield. Large-colony TK-/- mutants probably represent point or gene mutations affecting the TK locus. In addition, a class of small-colony TK(/- mutants are described and characterized as being heritably growth-deficient; this and other properties suggest that these small-colony TK-/- mutants originate by a heritable and viable chromosomal aberration. Most carcinogens and mutagens tested produce both classes of TK-/- mutants in this system; the relative proportions of small- and large-colony mutants are both mutagen- and dose-dependent. Comparative studies have been done at the rapidly-expressing TK locus and the slowly-expressing HGPRT locus in these cells. Several carcinogens detected at the TK locus are non- or very weakly mutagenic at the HGPRT locus. This findings is consistent with the induction of slow-growing specific locus mutants by a chromosomal mechanism and their subsequent dilution during this long expression time.

Opiate-Like Materials in the Adrenal Medulla: Evidence for Storage and Secretion with Catecholamines

Abstract: Opiate-like materials, as measured by the radioreceptor assay, were found in the adrenal gland of 7 mammalian species including man. The opiate-like materials are confined to the adrenal medulla, and followed a pattern identical to catecholamines on differential and isopycnic centrifugation. In the isolated perfused dog adrenal gland, acetylcholine stimulates a Ca2+-dependent secretion of opiate-like materials and catecholamines in the same molar ratio as they are stored within the chromaffin cell. Ba2+ also stimulates the secretion of both products from the adrenal gland. Separation of the opiate-like materials by Sephadex G-50 and reverse phase high pressure liquid chromatography indicates the presence of four peaks of opiate-like materials of molecular weights below 2,000. Two of these peaks comigrate in these systems with authentic met- and leu-enkephalins and react with the corresponding antibodies. These results indicate that enkephalins and other low molecular weight opiate-like materials are stored in and secreted from the chromaffin vesicles with catecholamines in the adrenal glands. These findings support a role for enkephalins as neurotransmitters and/or neurohormones. Also, they suggest that enkephalins and other opiate-like materials may exert important neuroendocrine functions outside the central nervous system.

Multiple Opiate Receptors: Different Regional Distribution in the Brain and Differential Binding of Opiates and Opioid Peptides

Abstract: In rat brain membrane preparations, the parenterally and orally active peptide, [D-Ala2, MePhe4, Met(O)5-ol]-enkephalin, binds to morphine receptor sites ([3H]naloxone or [3H]dihydromorphine binding sites) with an affinity higher than that for enkephalin receptor sites ([125I] [D-Ala2, D-Leu5]-enkephalin binding sites). [125I] [D-Ala2, MePhe4, Met(O)5-ol]-enkephalin binds to morphine receptor sites stereospecifically, in a saturable manner and with characteristics similar to that of [3H]dihydromorphine; this ligand can be used as an 125I-labeled probe to measure specific binding to morphine receptor sites. Na+ decreases and Mn2+ increases the binding capacity with a concomitant reduction of affinity for [125I] [D-Ala2, MePhe4, Met(O)5-ol]-enkephalin. This peptide does not bind to neuroblastoma cells with high affinity. The brain regional distribution of binding of [125I] [D-Ala2, MePhe4, Met(O)5-ol]-enkephalin or [3H]naloxone and [125I] [D-Ala2, D-Leu5]-enkephalin are different. The differential potency of binding of opiate agonists, antagonists, mixed agonist-antagonists, enkephalins and enkephalin analogues is studied by competition of binding of [3H]naloxone or [125I] [D-Ala2, MePhe4, Met(O)5-ol]-enkephalin (morphine receptor) and of [125I] [D-Ala2, D-Leu5]-enkephalin sites (enkephalin receptor). All of these results support the contention that there are multiple opiate receptors with differing characteristics.

The membrane attachment protein for spectrin is associated with band 3 in human erythrocyte membranes.

Abstract: Ankyrin, the membrane attachment protein for human erythrocyte spectrin, is tightly linked in a 1:1 molar ratio with band 3 in detergent extracts of spectrin-depleted membranes. Ankyrin-linked band 3, which represents 10--15% of the total band 3, spans the membrane, and is nearly identical to the major band 3 by peptide analysis. Spectrin binds to solubilised ankyrin-linked band 3, but not to free band 3. A portion of band 3 remains firmly associated with detergent-extracted cytoskeletal proteins. It is concluded that a fraction of band 3 is attached to the erythrocyte cytoskeleton through association with ankyrin, which in turn is bound to spectrin.

Specific nonopiate receptors for beta-endorphin

Abstract: Iodinated beta H-[2-D-alanine]endorphin exhibits specific binding to cultured human lymphocytes The binding is inhibited by low concentrations of beta-endorphin and its D-alanine derivative, but is not affected by opiate agonists and antagonists, or by enkephalin analogs, beta-lipotropin, adrenocorticotrophic hormone, or alpha-melanocyte-stimulating hormone; this suggests the existence of a specific, non-opiate binding site (receptor) for beta-endorphin The carboxy-terminal region of beta-endorphin is essential for this binding activity, since alpha-endorphin is not active beta-Endorphin may be a circulating hormone with peripheral physiological effects that are not primarily mediated through interactions with opiate or enkephalin receptors

Sustained Drug Delivery Systems I. The Permeability of Poly(e-Caprolactone), Poly(DL- Lactic Acid), and Their Copolymers

Abstract: The maximum steady state flux, diffusion coefficients, and solubilities of five contraceptive steroids in homopolymers and copolymers of epsilon-caprolactone and DL-lactic acid were determined. The permeabilities of polymers of epsilon-caprolactone were comparable to silicone rubber and, by inference, are suitable for the construction of drug delivery devices. Poly(DL-lactic acid) was 10(4) times less permeable, although its permeability was significantly enhanced by additives.

Local aggregation of hormone-receptor complexes is required for activation by epidermal growth factor.

Abstract: An analogue of epidermal growth factor (EGF) which is virtually devoid of biological activity retains receptor binding activity but cannot form cell surface clusters or patches. Bivalent anti-EGF antibodies restore both bioactivity and patch formation. The sensitivity of fibroblasts to native EGF can also be enhanced greatly by these antibodies, especially in hormone-resistant cell lines.

Polylactide. II. Viscosity–molecular weight relationships and unperturbed chain dimensions

Abstract: Mark–Houwink equations for benzene and chloroform solutions of S-polylactide and racemic polylactide were established by end-group analysis of partly hydrolyzed polymers. Unperturbed chain dimensions calculated for both polymers reveal a considerable difference and suggest a helical conformation for S-polylactide in solution. This finding supports 1H-NMR observations that reveal chemical shift differences that appear when the same configurational sequence is present in two stable conformational states.

Receptor-mediated internalization of fluorescent chemotactic peptide by human neutrophils.

Abstract: Tetramethylrhodamine labeled N-formyl-Nle-Leu-Phe-Nle-Tyr-Lys is a potent chemoattractant for human neutrophils. Binding of this peptide to living neutrophils was observed by means of video intensification microscopy. At 37 degrees C, diffuse membrane fluorescence was seen initially, followed by rapid aggregation and internalization of the fluorescent peptide. These processes are dependent on specific binding to the formal peptide chemotactic receptor.

Effect of Acycloguanosine Treatment on Acute and Latent Herpes Simplex Infections in Mice

Abstract: Systemic treatment of mice with the nucleoside analog 9-(2-hydroxyethoxymethyl)guanine (acycloguanosine [aciclovir]) was found to be highly effective against acute type 1 herpes simplex virus infection of the pinna. The drug ablated clinical signs and reduced virus replication both in tissue local to the inoculation site and within the nervous system. Provided that moderate-sized virus inocula were used, acycloguanosine treatment reduced or prevented the establishment of a latent infection in the dorsal root ganglia relating to the sensory nerve supply of the ear. However, although it aborted artificially produced infections in dorsal root ganglia, acycloguanosine was found not to be effective against the latent infection once established. This finding strongly indicated that latent herpes simplex virus in mice can exist in a nonreplicating form.

Immunoreactive forms of human erythrocyte ankyrin are present in diverse cells and tissues

Abstract: Ankyrin is a polypeptide of molecular weight (MW) 200,000 which is tightly bound to the cytoplasmic surface of the human erythrocyte membrane and has been identified as the high-affinity membrane attachment protein for spectrin1–3. This protein has also been shown to be associated with band 3 (ref. 4), the major transmembrane protein in erythrocytes. Ankyrin is thus an example of a polypeptide which links a cytoplasmic structural protein to an integral membrane protein. A water-soluble, 72,000-MW, proteolytic fragment of ankyrin has been purified which retains the ability to bind to spectrin, and competitively inhibits reassociation of spectrin with membranes5. Monospecific antibodies directed against this fragment have been prepared1 and demonstrated to cross-react only with ankyrin among the erythrocyte membrane proteins1,4. The present study reports the use of these antibodies to develop a radioimmunoassay capable of detecting femtomolar quantities of ankyrin, and demonstrates the presence of small but significant amounts of immunoreactivity in a variety of types of cells and tissues.

Highway Modeling. Part I: Prediction of Velocity and Turbulence Fields in the Wake of Vehicles

Abstract: A theory for the velocity deficit in the wake of a moving vehicle in still air is derived from a perturbation analysis of the equations of motion. By suitable assumptions, expressions are found for the turbulent energy fluctuations in the wake. This theory is then applied to predict the velocity deficit and turbulent energy fluctuations on a difference net in the x-z plane across the roadway for the case of the wind speed being much less than the vehicle speed (i.e., the GM experiment). The predictions are then compared to data from the General Motors Sulfate Dispersion Experiment. Comparison of observations to predictions show that the theory predicts the velocity deficit and turbulent fluctuations accurately.

Late Quaternary extent of the West Antarctic ice sheet: New evidence from Ross Sea cores

Abstract: Ross Sea cores contain diatom floras and have sediment characteristics which suggest that grounded ice filled the Ross Sea embayment to the continental shelf margin during the last, and previous, glacial advances. Each successive advance reworked sediments from the previous interglacial period with older material and compressed them into a firm deposit with reworked (mixed and fractured) microfossils. As the grounding line retreated past each core location, subglacial meltwater, tidal pumping, and marine bottom-water flow winnowed light, less heavily silicified diatoms, leaving a lag of Eucampia balaustium in well-sorted, sandy sediment. Warm-water, open-marine conditions initially prevailed after deglaciation on the northern part of the continental shelf during summers. Open-marine conditions were gradually replaced by the pack-ice cover that today characterizes the Ross Sea continental shelf region.

Opiate (Enkephalin) receptors of neuroblastoma cells: occurrence in clusters on the cell surface

Abstract: A bioactive, fluorescent derivative of enkephalin, Tyr-D-Ala-Gly-Phe-Leu-Lys-rhodamine, was used to determine the distribution of opiate receptors in living neuroblastoma cells. The receptors appeared in clusters on the cell surface, and no internalization was detected. No specific fluorescence or clusters were observed in the presence of [D-Ala2, Leu5]enkephalin or at 4 degrees C, and the clusters were much reduced under ionic conditions (that is, with 100 millimolars sodium) that specifically decrease the binding of opiate agonists.

Direct measurements of emission rates of some atmospheric biogenic sulfur compounds

Abstract: Direct measurements of H 2 S + COS and (CH 3 ) 2 S emission rates were made in two salt marshes on the coast of North Carolina during the summer of 1977. An emission flux reactor (chamber) technique was used to determine the emission rates of sulfur compounds into the atmosphere. The sulfur gases were identified and their concentrations in the flux reactor measured with a gas chromatograph equipped with a flame photometric detector specific for S. Flux measurements were made over salt marsh grass ( Spartina alterniflora ) and mud flats. The predominant gaseous sulfur species being emitted over the Spartina zone is (CH 3 ) 2 S (average flux is ?0.66 g S/m 2 /yr), and the predominant species over the mud flat zone is H 2 S + COS (average flux is ?0.2 g S/m 2 /yr). In general, the emission rates of (CH 3 ) 2 S and H 2 S + COS increase with increasing ambient temperature (in accordance with previously reported work over mud flats). Similar experiments were also performed in which the chamber was operated under deaerated (N 2 ) conditions. For deaerated conditions, the emission rates of both H 2 S + COS and (CH 3 ) 2 S were increased. DOI: 10.1111/j.2153-3490.1979.tb00895.x

4-aminobutyrate:2-oxoglutarate aminotransferase in blood platelets

Abstract: Platelet lysates obtained from blood of humans, dogs, and rats catalyzed the transamination of 4-aminobutyrate with 2-oxoglutarate as cosubstrate. Human platelet 4-aminobutyrate:2-oxoglutarate aminotransferase (36.5 +/- 3.2 picomoles per minute per milligram of platelet protein) resembled the brain enzyme in kinetic properties and in response to cofactors and inhibitors.

The effect of 2,4‐diaminotoluene and isomers of dinitrotoluene on unscheduled dna synthesis in primary rat hepatocytes

Abstract: The important industrial chemicals 2,4-dinitrotoluene (DNT) and 2,4-diaminotoluene (DAT) are hepatocarcinogens in rats. Technical grade DNT contains approximately 76% 2,4-DNT, 19% 2,6-DNT, and lesser amounts of the other isomers. The ability of 2,4-DAT, technical grade 2,4-DNT, and the purified isomers 2,3-DNT, 2,4-DNT, 2,5-DNT, 2,6-DNT, 3,4-DNT and 3,5-DNT to damage the DNA of primary rat hepatocytes was examined. Male Fischer-344 rats were perfused in situ, single cell suspensions were obtained after liver dissociation, and cultures of these cells were treated in the presence of 3H-thymidine. Autoradiography was employed to visualize label incorporation following repair of DNA. At the nontoxic (as judged by cell morphology) doses of 1 x 10(-4) M and below, only 2,4-DAT induced a significant response (ie an average greater than 5 grains net/nucleus). The activity seen with 2,4-DAT suggests that damage to the DNA of the hepatocytes may play a role in its carcinogenic activity and is consistent with the proposal that the induction of DNA repair in primary hepatocytes is of value in predicting the activity of aromatic amino compounds. However, the carcinogenic activity of the dinitrotoluenes was not reflected as DNA repair in the isolated hepatocyte, indicating that additional factors involving the whole animal also play a role in the mechanism of action of DNT.

Role of disulphide and sulphydryl groups in clustering of enkephalin receptors in neuroblastoma cells.

Abstract: Image intensified fluorescence microscopy has been very useful in visualising the patterns and mobility of receptors for epidermal growth factor (EGF), insulin and α2-macroglobulin in intact cells1,2. Recently, we have synthesised a bioactive derivative of enkephalin3, Tyr-D-Ala-Gly-Phe-Leu-Lys-rhodamine, and used it for the microscopic visualisation and localisation of opiate (enkephalin) receptors in neuroblastoma cells4. In contrast to the case of polypeptide hormones1,2, where fluorescently labelled receptors are initially distributed uniformly and quickly form patches which are subsequently internalised1,2, the enkephalin-labelled receptor patches in neuroblastoma cells appear only slowly and are not internalised4. Sulphydryl groups are involved in the binding of opiates to brain membranes and may affect differentially the binding of agonists and antagonists5,6. Also, sulphydryl and disulphide groups are involved in the binding sites of adrenergic, cholinergic and muscarinic receptors7–11. These observations prompted us to examine the effects of disulphide and sulphydryl reagents on the clustering of opiate (enkephalin) receptors in N4TG1 neuroblastoma cells. We report here that in these cells there are reactive sulphydryl and disulphide groups which are essential for cluster formation (but not binding), and that a sulphydryl–disulphide exchange reaction may be involved in this process. In addition, the sulphydryl reagents seem to dissociate the two steps of binding and cluster formation, and thus provide a tool for studying the pharmacological importance of receptor clustering.

Remote measurement of gaseous pollutant concentrations using a mobile Fourier transform interferometer system.

Abstract: A commercial Fourier transform interferometer system with telescopic optics has been installed in a van and used to make long-path absorption and single-ended emission measurements of gaseous pollutant concentrations at a number of geographical locations. The system covers the IR spectra region from 650 cm−1 to 6000 cm−1 at a maximum resolution of 0.06 cm−1. For many pollutants, concentrations in the 1–10-ppb range can be detected over a 1-km path length. To date, measurements have been made in the absorption mode across fertilizer plant gypsum ponds, an oil refinery, and jet engine plumes; industrial stacks, waste gas flares, and jet engine plumes have been studied in the emission mode.

Carbon disulphide and carbonyl sulphide from biogenic sources and their contributions to the global sulphur cycle

Abstract: Estimates of the magnitude of biogenic sulphur emissions range from ∼70% of the total atmospheric sulphur burden1–7, and the chemical nature of the emissions has not been clearly established. Conway1 speculated that the principal volatile biogenic component of the sulphur cycle was hydrogen sulphide (H2S) whereas Lovelock et al.8 and Rasmussen9 have suggested that dimethyl sulphide (DMS) contributes to the apparent source deficits. Aneja et al.10 have shown that both H2S and DMS are emitted from saltmarshes. Other volatile sulphur compounds which may contribute to the sulphur burden of the atmosphere include methyl mercaptan (CH3SH)11,12, dimethyl disulphide ((CH3)2S2)11,12, carbonyl sulphide (COS)13 and carbon disulphide (CS2)14,15. We report here the discovery of CS2 and COS emanating from a saltmarsh and estimate their emission rates using emission flux reactor and bag chamber techniques. The species CS2 and COS are relatively inert in the troposphere, so may be assumed to penetrate to the stratosphere, where they may be photolysed to form the sulphur dioxide (SO2) and sulphates (SO42−) known to be present in the stratosphere. Based on the measured fluxes, we show that the emissions from marshes are important to the sulphate aerosol burden (≲19%) of the stratosphere, but not important for the tropospheric sulphur burden (≲0.2%).