Protection against acute paraquat toxicity by ambroxol

An expression vector for G-CSF, pASLB3-3, was constructed and introduced into Namalwa KJM-1 cells (Hosoi et al., 1988), and cells resistant to 100 nM of methotrexate (MTX) were obtained. Among them, the highest producer, clone SC57, was selected and the productivity of this clone was further characterized. The maximal production of G-CSF was at the most 1.8 g/ml/day using a 25 cm² tissue culture flask, even though the cell number was above 7×10⁵ cells/ml. The limiting factors at high density were analyzed as the deficiency of nutrients, such as glucose, cysteine and serine, and pH control. The depression of specific G-CSF productivity per cell under the batch culture conditions was overcome by using a perfusion culture system, Biofermenter^TM (Sato, 1983) with modifications of nutrients supplementation by a dialysis membrane and/or dissolved oxygen (DO) supplementation by microsilicone fibers. ITPSGF medium was modified to elevate concentrations of amino acids and glucose by 2.0- and 2.5-times, respectively. Under the control of pH at 7.4 and DO at 3 ppm, the specific G-CSF productivity was not depressed even at high cell density (above 1×10⁷ cells/ml), and the amount of G-CSF reached 41 g/ml. These results indicated the possibility of finding the optimum culture conditions for the production of recombinant proteins by Namalwa KJM-1 cells.Abbreviations ABTS 2,2-Azino-di-(3-ethylbenzothiazoline)-6-sulfonic acid - BSA Bovine Serum Albumin - BSA-PBS Phosphate-buffered Saline without Ca²⁺ and Mg²⁺ containing Bovine Serum Albumin - dhfr Dihydrofolate Reductase - DO Dissolved Oxygen - G-CSF Granulocyte Colony-stimulating Factor - HEPES 4-(2-Hydroxyethyl)-1-piperazineethansulfonic Acid - IFN Interferon - MTX Methotrexate - PBS(-) Phosphate-buffered saline without Ca²⁺ and Mg²⁺ - Tween-PBS Phosphate-buffered saline without Ca²⁺ and Mg²⁺ containing 0.05% of Tween 20     

Cloning of the ColE3-CA38 colicin and immunity genes and identification of a plasmid region which enhances colicin production

The colicin and immunity genes of plasmid ColE3-CA38 have been localized by characterization of bacteria carrying its cloned restriction fragments. They are within a 3.14-kb EcoRI segment, such that the immunity gene contains the KpnI site, and the colicin gene is adjacent to it within a 2.1-kb KpnI-HincII segment. The immunity gene and one end of the colicin gene are in the region of ColE3-CA38 which is not homologous to the closely related plasmid ColE2-P9. A 0.64-kb PvuI-EcoRI segment of the plasmid adjacent to that containing the colicin and immunity genes was found to augment colicin production on solid media, and also affected the morphology of clearing zones produced by the cells when used as indicators in overlays of stabs of colicin E2 or E7 producers. The 0.64-kb segment was required in its native orientation relative to the 3.14-kb EcoRI segment to cause its effects.     

Investigations on radiosensitive and radioresistant populations of Drosophila melanogaster: X. The resistance factor rar 3: genetics

In earlier work, immature oocytes of the irradiated population RÖI₄ of Drosophila melanpgaster were found to be radioresistant relative to those of the basic population RÖI and to those of the control population Berlin wild (+K). The resistance of RÖI₄ relative to RÖI was previously attributed to a hypothetical “factor” rar-3. In the present paper, evidence is presented to show that rar-3 is a single, recessive genetic factor, located on chromosome 3 at a map position of about 49.8. The action of rar-3 is apparently independent of that of rar-1 and rar-2, the factors already present in RÖI.     

Heterocyclic polycyclic aromatic hydrocarbon carcinogenesis: 7H-dibenzo[c,g]carbazole metabolism by microsomal enzymes from mouse and rat liver

The metabolism of dibenzo[c,g]carbazole (DBC), was studied in vitro using microsomal fractions of mouse and rat liver from animals, which were treated with 3-methylcholanthrene (MC). The separation of extractable metabolites by high pressure liquid chromatography (HPLC) and thinlayer chromatography (TLC) as well as identification of most of them by nuclear magnetic resonance, mass spectrometry and comparison with synthetically obtained products are described. The microsomes of both species produced the same twelve compounds of which the following have been identified: five monohydroxylated derivatives (phenols), the product of further oxidation of one of them, and a dihydrodiol. The 5-OH-DBC (60% including its spontaneously-formed dimer) and the 3-OH-DBC (14%) are the main metabolites. Three minor metabolites cochromatographed with synthetically prepared 2-OH-DBC, 4-OH-DBC and 6-OH-DBC. The dihydrodiol detectable in small quantity (4–6%) was tentatively identified as 3,4-dihydroxy-3,4-dihydro-DBC by the sensitivity of its formation to very low concentrations of the inhibitor of microsomal epoxide hydrolase, 1,1,1-trichloropropene oxide, by its molecular ion and major fragment in mass spectrometry and by its dehydration product 3-OH-DBC. No other dihydrodiols were detected. The qualitative and quantitative effects of various modulators of metabolism (enzyme inhibitors, apparently homogeneous epoxide hydrolase, glutathione, supernatant fraction) were investigated. The results are discussed with respect to possible ultimate carcinogens.     

Ellipticines and human liver microsomes: Spectral interaction with cytochrome P-450 and hydroxylation. Inhibition of aryl hydrocarbon metabolism and mutagenicity

Some pharmacological properties of ellipticine (E) and its derivatives linked to their interaction with cytochrome P-450 have been investigated with human liver microsomes. 9-Hydroxyellipticine (9-OHE) interacts with human liver cytochrome P-450 exhibiting a type II spectrum (λ_max: 428 nm, K_s = 1.1 μM). After incubation with human liver microsomes the E was converted to 9-OHE; 7-hydroxyellipticine was not produced. The cytotoxic effect of this biotransformation has been evaluated on leukemic L1210 cells, in vitro, and found to be equal to those elicited by liver microsomes of control or phenobarbital (PB) pretreated rats. Moreover, 9-OHE and 9-fluoroellipticine (9-FE) strongly inhibit the benzo[a]pyrene hydroxylase (AHH) activity of human liver microsomes (I₅₀ = 2.6 μM and 1.6 μM, respectively) as well as the mutagenesis induced by the polycyclic aromatic hydrocarbon 2-acetylaminofluorene (AAF); 1 μg/plate of each of these compounds is able to inhibit by more than 50% the mutagenicity of 5 μg/plate AAF.     

Synthesis and relative stereochemistry of the four mercapturic acids derived from styrene oxide and N-acetylcysteine

The chemical reaction between (±)-styrene oxide and N-acetylcysteine produces both positional isomers ($\text{1}$ and $\text{2}$) as a mixture of diastereoisomers with a preference for the benzylic thioether isomer $\text{1}$ (2 : 1). Synthesis of the mercapturic acid conjugates from either (+)- or (?)-styrene oxide produces only two of the four possible stereoisomers. The single diastereoisomers of $\text{1}$ and $\text{2}$ were separated by high pressure liquid chromatography (HPLC) and identified by ¹H- and ¹³C-nuclear magnetic resonance (NMR). The relative stereochemistry at the benzylic carbon center of the mercapturic acid conjugates was assigned on the basis of the established chemical correlation between optically pure styrene oxide and its precursor mandelic acid, and considerations on the mechanism of ring opening of epoxides by sulfur nucleophiles. The stereochemical definition of the isomers $\text{3}$–$\text{6}$ should prove useful in investigations of the biotransformation of the glutathione (GSH) conjugates of styrene oxide.     

Phytoplankton ecology of the Lake of Menteith,Scotland

The results discussed in this paper represent the first seasonal ecological study carried out on the phytoplankton of the Lake of Menteith. All measured nutrients reached maximum levels during the winter, with silicate showing particularly high concentrations (up to 85 µg at Si l^–1). During the summer period phosphate, nitrate and silicate showed almost complete exhaustion in surface waters. The lake water was consistently alkaline, never falling below pH 7, while the alkalinity ranged from 20 to 24 mg CaCO₃ l^–1. Generally, the nutrient status of the main inflow had a rapid effect on the water quality of the lake.The region of the lake under investigation showed no thermal stratification at any period of the year, although continuous thermal gradients were recorded in the winter. The continual circulation of the water mass probably prevented oxygen saturation from falling below 77% even following a large phytoplankton bloom and subsequent decomposition.From an examination of net phytoplankton samples the Lake of Menteith could be described as blue-green or blue-green/diatom in nature. From the quantitative study, large pulses of Melosira, Asterionella and Fragilaria were recorded in the spring. The disappearance of the species appears to be related to silicate limitation. The summer growth of Asterionella may have been promoted by a nitrogen source other than nitrate and nitrite, both of which were reduced to critical levels. This alternative source of combined nitrogen may have been contributed by nitrogen-fixing algae in the lake. Three species of Anabaena were recorded, all of which produced large populations during the year.Department of Botany, The University of GlasgowPresent Address: Department of Biology, College of Science, University of Sulaimaniyah, Sulaimaniyah, Iraq     

Distribution of chylomicron degradation products in the isolated,perfused rat heart

Chylomicron degradation by hearts from fed and fasted rats was studied using a perfusion technique, which allows the separate collection of coronary (Q_rv) and interstitial effluent (Q_i). Upon perfusion with [³H]-cholesterol-containing chylomicrons the tissue recovery of label was highest in the fasted state, while label recovered in Q_i was highest in the fed state. Density gradient centrifugation of Q_i indicated that the label was recovered in lipoproteins with higher densities: low density lipoproteins (1.019<d<1.050), high density lipoproteins (1.050<d<1.21) and a fraction of d>1.21. These particles probably represent chylomicron degradation products (remnants and “surface fragments”). Our results indicate that tissue cholesterol uptake during chylomicron degradation may be inhibited in the fed state. Furthermore, the role of the myocyte (or interstitial) lipoprotein lipase in chylomicron degradation is discussed.     

Photooxidation products of 7,12-dimethylbenz[a]anthracene.

The principal products of the photooxidation of 7,12-dimethylbenz[a]-anthracene (DMBA) in aqueous solutions by photooxidation induced by laboratory lighting have been characterized by high performance liquid chromatograms (HPLC), ultraviolet and mass spectrograms and by comparisons with authentic samples. The products identified were the 7,12-epidioxy-7,12-dihydro-7-12-dimethyl-, 7,12-dione, 7-hydroxymethyl-12-methyl-, 12-hydroxymethyl-7-methyl-, 7-formyl-12-methyl-, 12-formyl-7-methyl-, and 12-hydroxy-12-methyl-7-one derivatives of benz[a]-anthracene. The HPLC profile of products is similar to that obtained from oxidation of DMBA by 'one-electron' reagents, singlet oxygen, or liver microsomal metabolism. The first points of attack are the 7- and 12- positions. The mechanism of photooxidation appears to be generation of singlet oxygen by photodynamic effect of DMBA. None of the products is photosensitizing, however.