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At least 937 records · Page 52Linked to original sources
PubMed2000

Elevated airway GSH resynthesis confers protection to Clara cells from naphthalene injury in mice made tolerant by repeated exposures.

Repeated exposures to Clara cell cytotoxicants, such as naphthalene (NA), render target cell populations resistant to further acute injury. Previous studies suggest that alterations in bioactivation enzymes in target sites (bronchioles) of tolerant mice are insufficient to account for the marked reduction in susceptibility. Mice were made tolerant by seven daily injections of NA. GSH in the terminal airways was 2.7-fold greater in tolerant mice than in vehicle controls and a NA (300 mg/kg) challenge dose did not produce injury. Tolerant mice, allowed to recuperate for 96 h after the seventh NA injection, were again susceptible to NA injury, and terminal airway GSH levels had declined to control levels. To determine whether alterations in GSH resynthesis account for tolerance, the activity of gamma-glutamylcysteine synthetase (gamma-GCS) was measured or mice were treated with a combination of buthionine sulfoximine (BSO), a gamma-GCS inhibitor, and NA. gamma-GCS activity was elevated in resistant airways of tolerant mice. Tolerant mice treated with both BSO and NA appeared as susceptible to injury as NA-challenged controls. We conclude that GSH is critical for Clara cell resistance to NA injury in tolerant mice because: 1) GSH levels in target airways from NA-tolerant animals are elevated; 2) after a 96-h recuperation period, tolerant mice had lower GSH levels and are again susceptible to NA injury; 3) alterations in the activity of gamma-GCS correspond with changes in susceptibility to NA injury; and 4) inhibition of gamma-GCS with BSO increases susceptibility to NA injury in tolerant mice.

Animals↗
PubMed2000

Polychlorinated naphthalenes in soil, sediment, and biota collected near a former chloralkali plant in coastal Georgia, USA.

Concentrations of total polychlorinated naphthalenes (PCNs) as high as 23 micrograms/g, dry wt, were found in sediments contaminated by the disposal of wastes from chlor-alkali processes. Concentrations of total PCNs in blue crab, fish and birds were 3- to 5-orders of magnitude less than that in sediments. The profile of PCN congeners in biota was predominated by tetra- or penta-chloronaphthalenes, while hepta- and octa-chloronaphthalenes were dominant in sediments. The 2,3,7,8-tetrachlorodibenzo-p-dioxin equivalents (TEQs) estimated for PCNs in sediments and biota were greater than those reported for PCBs, PCDDs or PCDFs. These results suggest that chlor-alkali process is a source of PCNs found in the environment.

Animals↗
PubMedDate not supplied

Determination of the fungicide ferbam in wheat grains after adsorption onto microcrystalline naphthalene.

A procedure was developed for the determination of iron(III) dimethyldithiocarbamate by converting it into iron(II)-bathophenanthroline-tetraphenylborate complex, which was then adsorbed onto microcrystalline naphthalene. The absorbance was measured at 534 nm against a reagent blank. Beer's Law was obeyed over the concentration range of 0.4-20 microg mL in final solution. Ten replicate determinations on 70 microg ferbam solutions gave a mean absorbance of 0.36, with a relative standard deviation of 0.91%. The method is sensitive and highly selective. It was applied for the determination of ferbam in a commercial sample and in mixtures with various dithiocarbamates (ziram, zineb, maneb) and wheat grains.

Adsorption↗
PubMed2001

Polychlorinated naphthalenes, biphenyls, dibenzo-p-dioxins, and dibenzofurans as well as polycyclic aromatic hydrocarbons and alkylphenols in sediment from the Detroit and Rouge Rivers, Michigan, USA.

Sediment from the upper Detroit and lower Rouge Rivers in southeastern Michigan, USA, were analyzed to examine the distribution of polychlorinated naphthalenes (PCNs), biphenyls (PCBs), dibenzo-p-dioxins (PCDDs), and dibenzofurans (PCDFs) as well as polycyclic aromatic hydrocarbons (PAHs) and alkylphenolic compounds such as butylphenol, octylphenol, and nonylphenol (NP). Sediments from a non-point source location in Lake Michigan were also analyzed for target compounds. Concentrations of target compounds in the upper Detroit and lower Rouge Rivers varied considerably among locations, and notable spatial variation existed. Concentrations of PCNs and PCDDs/PCDFs in sediments from the upper Detroit and lower Rouge Rivers ranged from 0.08 to 187 ng/g and 69 to 1420 pg/g dry weight, respectively. Total PCBs, PAHs, and NP concentrations ranged from 8 to 25,000, 17 to 44,000, and < 10 to 60,000 ng/g dry weight, respectively. Concentrations of all target compounds except PCNs were significantly correlated with total organic carbon content of sediments. Similarly, concentrations of PCBs, PCDDs, and PCDFs were significantly correlated with each other. The distribution of organic contaminants in the upper reaches of the Detroit River and lower Rouge River suggested the presence of localized, but multiple, sources of contamination for each compound class. Conners Creek combined sewer overflow has been identified as one of the potential sources for the upper Detroit River, where the highest concentrations PCBs and PCDDs/PCDFs were found. Polycyclic aromatic hydrocarbon and NP concentrations were consistently high in sediment from the lower Rouge River. Analysis of data from selected locations suggested that PCNs contributed a greater proportion of the dioxin-like activity than PCBs and PCDDs/PCDFs contributed.

Benzofurans↗
PubMedDate not supplied

Spectrophotometric determination of ziram in a commercial sample and wheat by extraction of its copper dimethyldithiocarbamate complex into molten naphthalene.

A method was developed for the determination of zinc(II) dimethyldithiocarbamate by converting it into the copper(II) dithiocarbamate complex, which is then extracted into molten naphthalene. The absorbance is measured at 430 nm versus a reagent blank. Beer's law is obeyed for concentrations of 0.63 x 10(-3) to 17.2 x 10(-3) g/L in the final solution. The method is sensitive and was applied to the determination of ziram in a commercial sample and in wheat grain.

Calibration↗
PubMed2002

Two new naphthalene and anthraquinone derivatives from Asphodelus tenuifolius.

Chromatographic separation of an ethanolic extract of rhizomes of Asphodelus tenuifolius Cav. (Asphodelaceae) yielded in addition to beta-sitosterol, stigmasterol and two anthraquinone derivatives, 1,8-dimethoxynaphthalene as well as two new naphthalene derivatives. The new compounds were identified as 2-acetyl-8-methoxy-3-methyl-1-naphthol and 2-acetyl-1,8-dimethoxy-3-methylnaphthalene. The separated compounds were identified on the basis of IR, MS, 1H and 13C NMR data.

Anthraquinones↗
PubMed2002

Polychlorinated-naphthalenes, -biphenyls, -dibenzo-p-dioxins, -dibenzofurans and p,p'-DDE in bluefin tuna, swordfish, cormorants and barn swallows from Italy.

Concentrations of p,p'-DDE, polychlorinated biphenyl congeners (PCBs), polychlorinated-dibenzo-p-dioxins (PCDDs), -dibenzofurans (PCDFs) and -naphthalenes (PCNs) were measured in bluefin tuna, swordfish, common cormorants, and barn swallows collected from Italy. Average concentrations of PCBs in livers of tuna, swordfish, cormorant, and swallows were 930, 745, 1420 and 1230 ng PCBs g-1, w.w. respectively. p,p'-DDE was found in tuna, swordfish, cormorant, and swallow livers at mean concentrations of 82, 135, 166 and 95 ng DDE g-1, w.w. respectively. PCNs were found in all the samples analyzed, although at concentrations less than those reported for biota from the Baltic Sea. PCBs, particularly, non-ortho coplanar PCBs accounted for 80-90% of the total TEQs in tuna and swordfish. Relative contribution of PCDDs/DFs to TEQs was greater in cormorants and swallows compared to that in fishes. PCDD/DF congeners accounted for up to 80 and 45% of the total TEQs in cormorants and swallows, respectively.

Animals↗
PubMed2002

Effect of pH on cadmium toxicity, speciation, and accumulation during naphthalene biodegradation.

Lowering pH of a microbiological medium from 7 to 4 decreased cadmium toxicity during naphthalene biodegradation by a Burkholderia sp. Cadmium speciation and cadmium accumulation in the system were studied to explain this effect. Cadmium speciation was determined by direct measurement and by geochemical modeling. Previous studies have implicated the monovalent hydroxylated cadmium (CdOH+) species in the effect of pH on cadmium toxicity. Modeling analysis predicted CdOH+ formation only at very low concentrations (< or = 0.0128 microM), while the measured concentration of divalent ionic cadmium (Cd2+) was at least three orders of magnitude greater, suggesting that Cd2+ is the more significant metal form. With respect to cadmium accumulation, cells contained in media adjusted to pH 4 accumulated only 2.76 +/- 0.76 mg Cd/g cells, whereas cells in media adjusted to pH 7 accumulated 8.52 +/- 0.71 mg Cd/g cells. These data suggest that cadmium toxicity is correlated with increased cadmium accumulation rather than the formation of CdOH as pH is increased. At low pH, the decrease in cadmium accumulation may be caused by increased competition between hydrogen and cadmium ions for binding sites on the cell surface or by an increase in metal efflux pump activity due to an increase in the proton gradient that drives the efflux pump.

Biodegradation, Environmental↗
PubMed2003

Spatial distribution of polychlorinated naphthalenes in air over the Great Lakes and air-water gas exchange in Lake Ontario.

High-volume air samples were collected during research cruises of Lake Superior in August 1996 and May 1997 and of Lake Ontario (North America) in July and September 1998 and June 2000 and analyzed for polychlorinated naphthalenes (PCNs). Levels of tetra- to octachloronaphthalene (sigmaPCN) varied spatially, with mean values (+/-SD) of 1.78 +/- 0.74 and 1.46 +/- 1.07 pg m(-3) for Lake Superior in 1996 and 1997, respectively, and of 5.53 +/- 2.19 and 5.60 +/- 2.24 pg m(-3) for Lake Ontario in 1998 and 2000, respectively. Evaporative sources were predominant, although combustion marker congeners such as tetrachloronaphthalenes 44 and 29 and pentachloronaphthalene 54 were present in most samples and were enhanced relative to technical PCN mixtures. The sigmaPCN concentrations were higher in Lake Ontario samples collected in the western half of the lake and when winds were from the west. Greater proportions of the population and industrial areas are located around the western part of Lake Ontario. Water-air fugacity ratios, calculated from air and water samples collected in June 2000, indicate that the trichloronaphthalenes are volatilizing from Lake Ontario, whereas the tetrachloronaphthalenes are close to equilibrium and the net deposition of tetrachloronaphthalenes can occur when the urban air plume influences levels over the lake.

Chlorine Compounds↗
PubMedDate not supplied

[Effect of naphthalene biodegradation plasmids on physiological characteristics of rhizospheric bacteria of the genus Pseudomonas].

Specific growth rate, duration of the lag phase, stability of plasmids, and activities of the key enzymes involved in naphthalene biodegradation were studied in rhizospheric pseudomonades carrying structurally similar plasmids pOV17 and pBS216. It was demonstrated that these plasmids determined various levels of catechol 2,3-dioxygenase activities. The structural rearrangements in the plasmid pBS216 could "switch off" the genes of catechol oxidation meta-pathway. It was shown that certain combinations of biodegradation plasmids and bacterial hosts, such as Pseudomonas chlororaphis PCL1391(pBS216), P. chlororaphis PCL1391(pOV17), and P. putida 53a(pOV17), were considerably more efficient than natural variants in their growth characteristics and stability of the biodegradation activity, having a potential for bioremediation of soils polluted with polycyclic aromatic hydrocarbons (PAHs).

Biodegradation, Environmental↗
PubMed2005

[Quantitative relationship between gas chromatographic retention indices and structural parameters of polychlorinated naphthalenes].

The structural and thermodynamic properties of 76 polychlorinated naphthalenes (PCNs) were fully computed at B3LYP/6-31G* level. Both structural and thermodynamic parameters of PCNs obtained were consequently taken as theoretical descriptors and correlated with their gas chromatographic retention indices (RI), so as to develop the relevant quantitative structure-retention relationship (QSRR) regression model (model I) with r2 of 0.9957, which possesses high correlation, high predictive power and clear physical interpretations. Secondly, another linear QSRR model (model II) was achieved by employing the number and position of chlorine substitution as descriptors, of which r2 was 0.9967, and also the main factors affecting the retention time of PCNs were investigated.

Chromatography, Gas↗
PubMedDate not supplied

[Oxidation of dibenzofuran by Pseudomonas strains harboring plasmids of naphthalene degradation].

Pseudomonas strains harboring plasmids pBS3, pBS4, NAH7 were shown to carry out initial transformation of dibenzofurane to 4-[2'-(3'-hydroxy)-benzofuranyl]-2-keto-3-butenic acid due to broad substrate specificity of the enzymes of naphthalene catabolism nahA, nahB, nahC and nahD. These strains did not grow on dibenzofurane because of the inability of the enzyme nahE to split pyruvate of 4-[2'-(3' hydroxy)-benzofuranyl]-2-keto-3-butenic acid, which leads to accumulation of the latter. The strains harboring plasmids pBS2 and NPL-1 are not capable of any transformation of dibenzofurane.

Benzofurans↗
PubMed1988

[Mutations of plasmid pBS286 blocking the initial stages of naphthalene oxidation induced by Tn5].

A collection of Tn5 transposon Nah- mutants of the plasmid pBS286 was obtained. The insertion sites were localized and orientation of Tn5 determined. The mutants obtained were biochemically analyzed, the nah-region map of the plasmid being elaborated. Structural genes of the nah operon were shown to be organized similarly to those of the nah1 operon of the NAH7 plasmid discussed in the literature. The data obtained are in favour of the previously published information on the presence of elements operating the pBS286 plasmid. The results are given indicating a possibility of regulating the expression of catechol splitting meta-pathway genes with participation of products on early stages of naphthalene oxidation.

Biodegradation, Environmental↗
PubMed1986

[Comparative analysis of the organization of the NPL-1 plasmid controlling naphthalene oxidation in Pseudomonas putida and its derivatives].

The paper contains the data on the structure of NPL-1 plasmid controlling naphthalene biodegradation. The plasmid which pertains to the P-9 incompatibility group is transferrable conjugatively and is maintained stably within a wide range of gram-negative bacteria. The analysis of mutants and transposon derivatives of the plasmid made it possible to localize nah-genes in a DNA fragment, 23 kb in size. An inverted DNA segment of 4.2 kb was discovered which may participate in the regulation of nah-genes expression. The other peculiar features of NPL-1 were found distinguishing it from NAH and NAH7 plasmids described in literature.

Biodegradation, Environmental↗
PubMed1979

[Ultra-violet spectrophotometry in drug control. Part 23: Conclusions from the spectrophotometric behaviour of drugs with pyridine, naphthalene, quinoline and isoquinoline chromophores (author's transl)].

The results from a systematic study of drugs with pyridine, naphthalene, quinoline and isoquinoline chromophores are evaluated and condensed into conclusions. In addition to previously reported findings, the ultra-violet and visible spectra of a further nine drugs containing the mentioned chromophores are presented.

Isoquinolines↗
PubMed1980

Inhibition of microsomal metabolism and chemical oncogenesis in culture by naphthalene quinones.

A series of naphthalene diols, quinones, and related compounds were examined for their ability to inhibit mixed-function oxidase in liver microsomes obtained from rats which had been pretreated with 3-methylcholanthrene (3-Mc) or phenobarbital (PB). Using benzo(a)pyrene monooxygenase as a measure of mixed-function oxidase activity, it was found that phenanthrene-9, 10-quinone was the most active compound tested with a K1 = 0.79 microM. Phenanthrene-9, 10-quinone did not affect cytochrome c reductase but did inhibit aminopyrine N-demethylase and p-nitroanisole-O-demethylase in both 3-MC and PB-induced microsome with almost identical inhibition constants. 1,2-Naphthoquinone exerted similar effects as phenanthrene-9,10-quinone on cytochrome c reductase, aminopyrine N-demethylase and p-nitroanisole-O-demethylase. Both quinones stimulated NADPH oxidase activity but the extent of this stimulation did not explain their inhibition of microsomal oxidation. Kinetic studies using benzo(a)-pyrene monooxygenase with phenanthrene-9, 10-quinone and 1,2-naphthoquinone indicated that they were noncompetitive with benzo(a)pyrene and mixed noncompetitive with NADPH. Both of these quinones inhibited benzo(a)pyrene induced oncogenic transformation in C3H10T1/2CL8 cells in culture in a dose response manner, presumably by inhibition of the cellular microsomal enzyme which activate benzo(a)pyrene. Phenanthrene-9, 10-quinone and 1,2-naphthoquinone seem to inhibit microsomal oxidative processes by interaction at the level of cytochrome P-450 possibly with a cytochrome P-450-substrate-oxygen complex.

Aminopyrine N-Demethylase↗
PubMed1981

Novel antimicrobial compounds among naphthalene and methylenedioxyphenyl derivatives.

2-Benzoyl-2-phenyl-4,5,6,7-tetrachlorobenzo-1,3-dioxole (1) undergoes Stobbe condensation readily with dimethylsuccinate in the presence of potassium tert-butoxide to give the acid ester (2a), which is converted into benzocyclopentadienone and naphthalene derivatives via two different routes. The in vitro antimicrobial spectra of these compounds were evaluated. Anhydride (3), phenolic acid (5b), carbamate (5c) and hydrazide (5e) are shown to possess high activity against all tested pathogenic gram-negative organisms in addition to Staphylococcus aureus and the tested yeast species.

Anti-Infective Agents↗