Showing papers by "Research Triangle Park published in 1986"

Insulin-stimulated hydrolysis of a novel glycolipid generates modulators of cAMP phosphodiesterase.

Abstract: Insulin action may involve the intracellular generation of low molecular weight substances that modulate certain key enzymes The production of two substances that regulate the activity of adenosine 3',5'-monophosphate phosphodiesterase was evaluated in cultured myocytes by incorporation of radiolabeled precursors Insulin caused the rapid hydrolysis of a chemically undefined membrane glycolipid, resulting in the production of two related complex carbohydrates as well as diacylglycerol Both the glycolipid precursor and the aqueous products were monitored by labeling with radioactive inositol and glucosamine Depletion of the labeled precursor and the appearance of labeled water-soluble products and diacylglycerol occurred within 30 seconds after hormone treatment and was followed by rapid resynthesis of the precursor The aqueous products that were radioactively labeled appeared chromatographically and electrophoretically identical to phosphodiesterase modulating activities produced by insulin from the same cells The purified radiolabeled and bioactive substances had similar chemical properties Hydrolysis of the glycolipid precursor and subsequent generation of products could be reproduced by incubation of extracted lipids with a phosphatidylinositol-specific phospholipase C These studies suggest that insulin stimulates an endogenous, selective phospholipase C activity that hydrolyzes a novel glycolipid, resulting in the generation of a complex carbohydrate-phosphate substance containing inositol and glucosamine that may mediate some of the actions of the hormone

The Salmonella typhimurium/mammalian microsomal assay. A report of the U.S. Environmental Protection Agency Gene-Tox Program.

Abstract: The Salmonella assay has been in use for almost 15 years and can be defined as a routine test for mutagenicity and for predicting potential carcinogenicity It detects the majority of animal carcinogens and consequently plays an important role in safety assessment The test is also routinely used as the frontline screen for environmental samples (complex mixtures) isolated from air, water and food This role will continue to remain an area of growth as or because sample volumes associated with these testing areas are generally very limited and more extensive testing is generally impossible While this test, like all others, has some limitations, it is recommended that it be regularly included in all genetic testing batteries

Suppression of mouse viraemia and retroviral disease by 3'-azido-3'-deoxythymidine.

Abstract: The retroviruses human T-cell lymphotrophic virus-I (HTLV-I)1,2 and HTLV-III/LAV (lymphadenopathy-associated virus)3,4 are clearly linked to human diseases. Patients with HTLV-I-positive neoplasms may respond transiently to traditional chemotherapy, but are not cured5. For patients with acquired immune deficiency syndrome (AIDS) there is no curative therapy6. In retroviruses of different species, viral propagation crucially depends on reverse transcriptase, an enzyme not present in normal mammalian cells and different from mammalian DNA polymerases, making it a target for specific inhibition. Reverse transcriptase has been well conserved through evolution: an LAV isolate contained a 250-amino-acid-long domain, presumably the reverse transcriptase core sequence, which has 21% homology to Moloney murine leukaemia virus (MoMLV)7. Because HTLV-IH infects only humans and chimpanzees8, we substituted murine retroviruses for in vivo evaluation of candidate anti-AIDS drugs after ascertaining similar inhibition in vitro of HTLV-III and MLVs, which were chosen for their short incubation time. The triphosphate of 3'-azido-3'-deoxythymidine (AZT)9–11 is incorporated into complementary DNA by retroviral reverse transcriptase, causing premature chain termination. Here we show that chronic AZT treatment of mice infected with Rauscher murine leukaemia virus complex (RLV) prevents infection of splenocytes and development of splenomegaly, and suppresses viraemia if started soon after inoculation. Starting AZT late in the course of disease still leads to significant prolongation of life; anaemia, however is a significant side-effect. By analogy, AZT may have a role in preventing retroviral disease in humans if started early after infection, and it may lead to significant survival gains even if started later in the course of disease.

Effect of specific surface area on the reactivity of CaO with SO2

Abstract: The paper discusses results of measuring the rate of reaction of calcined limestone (CaCO/sub 3/) with sulfur dioxide (SO/sub 2/) and oxygen (O/sub 2/) at conditions that eliminate all resistances not associated with the lime (CaO) grain surface. Reactivity increased with the square of the Brunauer, Emmett, and Teller (B.E.T.) surface area when grain size was varied as an experimental parameter. The observed effects of surface area and temperature account for the SO/sub 2/ capture reported for boiler tests of the limestone-injection process.

Statistical analyses for in vitro cytogenetic assays using Chinese hamster ovary cells

Abstract: It is a widely held view that objective statistical criteria are needed for the evaluation of genetic toxicity assays. This paper presents statistical methods for the analysis of data from in vitro sister chromatid exchange (SCE) and chromosome aberration tests that use Chinese hamster ovary cells. For SCEs, an extensive study of solvent control results demonstrated that there is a substantial interday component of variability in the data, and that a Poisson sampling model is applicable to data generated via the protocol of Galloway et al [1985]. Consequently, a trend test for evidence of a dose response is proposed for such SCE data. As an illustration of this statistical method, analysis of data previously considered to be negative [Gulati et al, 1985] indicates that di(2-ethyl-hexyl) phthalate induces a weak, but reproducible, SCE dose response in CHO cells. Monte Carlo methods are used to show that the trend test is more sensitive than four other statistical procedures considered for the analysis of Poisson-distributed SCEs. A similar trend test for dose response in proportions is proposed for chromosome aberration data, where the percent of cells with chromosome aberrations is the response of interest. Sensitivity (or power) studies indicate that three doses and a control with 50 cells/dose point is a reasonable design for an in vitro SCE study that uses the Galloway et al protocol. For in vitro chromosome aberrations, however, three doses and a control with 100 cells/dose point appears to produce too insensitive an assay; an increase to 200 cells/dose point in the Galloway et al protocol seems worthy of serious consideration.

Evaluation of the genetic activity profiles of 65 pesticides

Abstract: We have previously reported the qualitative results of a major study on 65 pesticides (Waters et al., 1982). Dose information from this investigation (either lowest effective or highest ineffective dose tested) has now been incorporated into a computerized data management system. This report focuses on the qualitative profiles of genetic activity produced by these pesticides and our efforts to classify them according to their genotoxic effects and chemical structures. Three main categories may be distinguished based on the qualitative results: Category 1 pesticides were active in most of the in vitro and in vivo assays employed. These 9 compounds include the structurally similar organophosphate insecticides, acephate, demeton, monocrotophos and trichlorfon; the phthalimide fungicide analogues, captan and folpet; and the thiocarbamate herbicide analogues, diallate, sulfallate and triallate. The 26 Category 2 compounds demonstrated fewer positive results and may be subdivided into two parts, one of which contains 12 halogenated aromatic or heterocyclic ring compounds, including the phenoxy herbicides, 2,4-D, 2,4-DB and 2,4,5-T. The remaining part of Category 2 (14 compounds) consists of structurally similar organophosphate insecticides, azinphos-methyl, crotoxyphos, disulfoton, methyl parathion; three similar ethylenebisdithiocarbamate fungicides, maneb, mancozeb, and zineb; three similar pyrethroid insecticides, allethrin, chrysanthemic acid, and ethyl chrysanthemate; and four structurally diverse compounds, cacodylic acid, dinoseb, sec. -butylamine and benomyl. The third category of 30 pesticides gave negative results in all tests and represents structurally diverse compounds. Using the computerized profile matching methodology, from 2080 possible pairwise chemical combinations of the 65 pesticides, 20 statistically significant pairs were selected. 6 groups of pesticides were identified which were substantially similar to groups of pesticides we had formed previously (Waters et al., 1982) based on genetic activity and chemical structure. The matches showed excellent qualitative and, in most cases, excellent quantitative agreement. Hence it appears that specific patterns of test results present in the genetic activity profiles are related directly to chemical structure. Conversely, the data suggests that certain groups of compounds may be recognized by a well defined series of concordant tests results. As additional data is added, comparison of test results for new chemicals with existing data for known genotoxicants should aid in the evaluation of potential genetic health hazards.

Models of hepatocarcinogenesis in the rat--contrasts and comparisons.

Abstract: (1986). Models of Hepatocarcinogenesis in the Rat—Contrasts and Comparisons. CRC Critical Reviews in Toxicology: Vol. 17, No. 1, pp. 61-89.

Econometric analysis of the factors influencing forest acreage trends in the southeast.

Abstract: Econometric models of changes in land use acreages in the Southeast by physiographic region have been developed by pooling cross-section and time series data. Separate acreage equations have been estimated for the three major private forestland owner classes and the three major classes of nonforest land use. Observations were drawn at three or four different points in time for the 21 Forest Survey Units in the Southeast. Of the variables examined, population and personal income measures were the major significant explanatory variables in the land use equations.

SOCRATES: A System for Automatically Synthesizing and Optimizing Combinational Logic

Abstract: This paper presents SOCRATES, a system of programs which synthesize and optimize combinational logic circuits from boolean equations. SOCRATES optimizes logic using boolean and algebraic minimization techniques, and it optimizes circuits derived from this logic in a user defined technology with a rule based expert system. This paper discusses the goals of logic synthesis and the capabilities needed in a tool to meet these goals. SOCRATES's capabilities are then presented and demonstrated with experiments run on circuits from the 1986 Design Automation Conference synthesis benchmark set.

Co–Transformation of Unlinked Foreign Genes into Plants by Direct Gene Transfer

Abstract: Direct gene transfer experiments were carried out to find the rate of co–transformation of non–selectable and selectable (kanamycin resistance) genes offered to tobacco protoplasts as naked DNA on separate plasmids. After co–transformation, we could detect the presence of sequences from a zein genomic clone in up to 88% of kanamycin resistant (pABDI containing) cell clones, and a fragment containing the full zein genomic clone was found in up to 33% of the latter cases. In co–transformations with a nopaline synthase gene, up to 47% of the kanamycin resistant clones obtained in one treatment contained the non–selected gene, and the gene was complete and active in all of these latter cases. The high efficiency of co–transformation shows that direct gene transfer provides a rapid and easy method of introduction of non–selectable genes into plant genomes.

Adenosine inhibits epileptiform activity arising in hippocampal area CA3.

Abstract: The ability of adenosine and structurally-related compounds to inhibit epileptiform activity induced by bicuculline in the CA3 region of the hippocampal slice of the rat was examined. Bath application of all purinoceptor agonists tested reduced the frequency of generation of burst potentials. Analysis of dose-response curves yielded the following IC50 values: adenosine, 1.5 microM; 2-chloroadenosine, 0.144 microM; 5'-(N-ethyl)carboxamidoadenosine, 30.2 nM; L-phenylisopropyladenosine, 12.1 nM; cyclohexyladenosine, 7.9 nM. Theophylline (30 microM) increased the rate of bursting and antagonized the effect of exogenous adenosine. Dipyridamole (0.03-1 microM) reduced the occurrence of burst firing. In slices untreated with bicuculline, theophylline (30 microM) and adenosine deaminase (10 micrograms ml-1) induced bursting activity. These results demonstrate that purinoceptor agonists can suppress epileptiform activity in the hippocampus and suggest that adenosine may act as an endogenous anticonvulsant.

Historic emissions of sulfur and nitrogen oxides in the United States from 1900 to 1980

Abstract: Historic emissions of sulfur oxides and nitrogen oxides were estimated for each state of the coterminous United States. The emissions were estimated by individual source category on the state level from 1900 to 1980 for every fifth year and for 1978. The source categories included power plants, industrial boilers, industrial processes, commercial and residential heaters, natural gas pipelines, highway vehicles, off-highway diesel engines, and all other anthropogenic sources. These emissions were calculated from salient statistics indicative of fuel consumption or industrial output, estimations of average statewide fuel properties, and estimations of emission factors specific to each source category over time. The emission estimates were then aggregated to show the emission trends by state, region, and all states combined. This paper summarizes the historic emission trends on a state, regional, and national scale. The trends are presented by source category and by major fuel type. The emission estimates al...

Temperature dependence of chromatic dispersion in single mode fibers

Abstract: This paper describes the temperature dependence of chromatic dispersion in single-mode fibers for a temperature range of -60°- 250°C. Highly accurate dispersion measurements demonstrated a linear relationship (0.025 nm/°C) between the zero dispersion wavelength and temperature for tests conducted below 150°C. Further tests in the high-temperature range showed an increase in this dependence. For both temperature ranges, the results were independent of fiber coating and structure.

Open systems interconnection

Abstract: The subject of Open Systems Interconnection (OSI) standardization is becoming increasingly important to the telecommunications and information processing communities. A number of OSI standards have been completed, others are near completion, and initial product offerings by vendors have begun. This paper briefly defines what OSI is, the interrelationships of the various standards bodies, and the goals and benefits to users, vendors, country post telephone and telegraph bodies, common carriers, and governments. The IBM view of OSI and how it relates to Systems Network Architecture is also discussed.

Angiotensin ii-like immunoreactivity in human ovarian follicular fluid

Abstract: Human ovarian follicular fluid (hFF) has angiogenic activity, although the causative factors are unknown. We recently found that hFF contains renin activity which converts renin substrate to angiotensin I (AI). Since the enzymatic cleavage product of AI, angiotensin II (All), is a potent stimulator of new vessel formation, we have examined Sephadex G-25 column fractions of hFF and extracted hFF and plasma from individual patients forAll-like immunoreactivity (AII-IR). Eluent fractions from Sephadex G-25column chromatography of hFF had significant AII-IR which eluted in the same fractions as synthetic All. Individual, extracted FF samples contained approximately 10 times higher levels of AII-IR than extracts of plasma from the same patients. Serial dilutions of the Sephadex column fractions and extracted FF and plasma inhibited binding of (125)I-AII to rabbit anti-All serum in a manner parallel to the inhibition caused by synthetic All, indicating that the detected immunoreactivity was not dueto non-specif...

Two unlinked T-DNAs can transform the same tobacco plant cell and segregate in the F1 generation

Abstract: The 200 kb Agrobacterium Ti-plasmid pTiT37 carries a 25 kb segment of T-DNA which it transfers to plant cells during crown-gall tumorigenesis. We have previously engineered into this T-DNA a pBR322-derived cloning vector which enabled us to rescue-clone full length T-DNA from the Ti-plasmid into a 36 kb MINI-Ti plasmid. We report here the deletion of oncogenes from MINI-Ti to produce Micro-Ti containing the nopaline synthase gene and the ampicillin resistance gene and origin of replication of pBR322, flanked by left and right T-DNA borders. Micro-Ti was recloned into the wide host range plasmid pRK290 and transformed into an A. tumefaciens strain carrying a helper plasmid that could supply Virulence (VIR) genes in trans. Using the octopine Ti-plasmid pTiB6-806 as a helper, transformed tobacco cells were obtained which produced both nopaline and octopine. Two cloned cell lines producing both opines were found to be hormone dependent and to produce fertile tobacco plants. We selfed one of these plants and found that the two opine markers segregated in the F1 progeny in a Mendelian fashion. This showed that the T-DNAs were not linked in the transformed plant genome. Southern blot analysis of the genomic DNA from the regenerated plant showed that only part of the (oncogenic) octopine T-DNA was present indicating that it had suffered a deletion in the auxin producing locus (tms region). Presence of the cytokinin autonomy locus presumably accounts for the abnormal rooting behavior of the F1 progeny seedlings containing this T-DNA.

Species comparison of acute inhalation toxicity of ozone and phosgene

Abstract: A comparison of the concentration-response effects of inhaled ozone (O3) and phosgene (COCl2) in different species of laboratory animals was made in order to better understand the influence of the choice of species in inhalation toxicity studies. The effect of 4-h exposures to ozone at concentrations of 0.2, 0.5, 1.0, and 2.0 ppm, and to COCl2 and 0.1, 0.2, 0.5, and 1.0 ppm was determined in rabbits, guinea pigs, rats, hamsters, and mice. Lavage fluid protein (LFP) accumulation 18-20 h after exposure was used as the indicator of O3- and COCl2-induced pulmonary edema. All species had similar basal levels of LFP (250-350 mg/ml) when a volume of saline that approximated the total lung capacity was used to lavage the collapsed lungs. Ozone effects were most marked in guinea pigs, which showed significant effects at 0.2 ppm and above. Mice, hamsters, and rats showed effects at 1.0 ppm O3 and above, while rabbits responded only at 2.0 ppm O3. Phosgene similarly affected mice, hamsters, and rats at 0.2 ppm and above, while guinea pigs and rabbits were affected at 0.5 ppm and above. Percent recovery of lavage fluid varied significantly between species, guinea pigs having lower recovery than other species with both gases. Lavage fluid recovery was lower following exposure to higher levels of O3 but not COCl2. Results of this study indicate that significant species differences are seen in the response to low levels of O3 and COCl2. These differences do not appear to be related in a simple manner to body weight.

Quantitative autoradiographic analysis of Mu and delta opioid binding sites in the rat hippocampal formation

Abstract: The distributions of mu and delta opioid binding sites were studied in rat hippocampal formation by using quantitative in vitro autoradiography. Mu binding sites, labeled with 125I-FK-33824, showed a highly organized laminar distribution. Binding was greatest at the foot of the obliterated hippocampal fissure in stratum lacunosum-moleculare of CA3. Stratum pyramidale and stratum lacunosum-moleculare of CA2 and stratum pyramidale of CA3 were next highest in mu binding, followed by stratum oriens and stratum radiatum of CA2, stratum oriens of CA3, and stratum pyramidale of CA1. The distribution of delta binding sites, labeled with 125.I-D-ala2 -Dleu5-enkephalin in the presence of the unlabeled mu receptor ligand PL-032, was similar to the distribution of mu binding in that binding within each region was greatest in a band centered over stratum pyramidale and in stratum lacunosum-moleculare. Over all, delta binding was greatest in CA2 followed by CA3 and then CA1. Compared to mu binding, delta binding was relatively enriched in stratum moleculare of the dentate gyrus. These laminar distributions correlate reasonably well with the distribution of enkephalin immuno-reactivity in hippocampal formation, although binding was surprisingly low in stratum lucidum, an area rich in dynorphin and enkephalin immunoreactivity.