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PubMed2003

Cell-transforming activity of fourteen chemical agents used in dental practice in Syrian hamster embryo cells.

Fourteen chemical agents used in dental practice were assessed for their cell-transforming activity using the Syrian hamster embryo (SHE) cell transformation assay system. The cell-transforming activity was quantitatively assessed by the frequency of morphological transformation (MT) in SHE cells induced by these agents. MT was induced by m-cresol, guaiacol, formaldehyde, sodium hypochlorite, hydrogen peroxide, sodium arsenite, acid fuchsin, and basic fuchsin, but not by p-chlorophenol, p-phenolsulfonic acid, glutaraldehyde, and erythrosine B. Iodine and chlorhexidine exhibited positive and pseudopositive responses, respectively. The chemical agents exhibiting a negative or pseudopositive response neither induced nor enhanced MT even in the presence of exogenous metabolic activation.

Animals↗
PubMed2005

Biodegradation of phenolic environmental pollutants by a surfactant-laccase complex in organic media.

Oxidative degradation of phenolic environmental pollutants in organic media was investigated using a laccase complexed with surfactants. The catalytic activity of the surfactant-laccase complex in isooctane was markedly enhanced by appropriately adjusting the water content of the reaction medium using reverse micelles. The surfactant-laccase complex showed little activity towards the oxidative reaction of bisphenol A in water-saturated isooctane (i.e., 0.0055% [v/v] water) while effectively catalyzed the same reaction in isooctane containing 4% (v/v) water, which is over the maximum water solubility. The latter system was homogeneous and was only achieved by the aid of reverse micelles. With respect to the oxidation of bisphenol A, two products, 4-isopropylphenol and 4-isopropenylphenol, were identified by gas chromatography-mass spectrometry (GC-MS) analyses, indicating the oxidative degradation of the bis-phenolic structure of bisphenol A. We also found that the surfactant-laccase complex turned out to handle other environmental pollutants, chlorophenols, by the simultaneous addition of water and a redox mediator into the reaction medium using reverse micelles.

Basidiomycota↗
PubMed2003

Is the decline of the increasing incidence of non-Hodgkin lymphoma in Sweden and other countries a result of cancer preventive measures?

Is the decline of the increasing incidence of non-Hodgkin lymphoma (NHL) in Sweden and other countries a result of cancer preventive measures? The yearly age-standardized incidence of NHL increased significantly in Sweden during 1971-1990, for men an average of 3.2% and for women 3.1%. The corresponding figures for 1991-2000 were -0.8% and -0.2%, respectively. A decline of the increasing incidence has also been seen in other countries, such as the United States, Finland, and Denmark. Immunosuppression is one established risk factor for NHL, possibly with interaction with Epstein-Barr virus. Phenoxyacetic acids and chlorophenols, both pesticides, have been associated with NHL. Use of these chemicals was banned in Sweden in 1977 and 1978, respectively. Also, persistent organic pollutants such as polychlorinated biphenyls, hexachlorobenzene, chlordanes, and dioxins have been shown to increase the risk. Exposure of the whole population occurs predominantly through the food chain. Exposure to such chemicals was highest in the 1960s and 1970s. Because of regulation in the 1970s, exposure has declined substantially in the population. The change in incidence of NHL in Sweden and other countries may serve as a good example of how prohibition and limitation of exposure may be reflected in cancer statistics some decades later.

Adolescent↗
PubMed1985

Analysis of polychlorinated dibenzofurans, dioxins and related compounds in environmental samples.

The analysis of polychlorinated dibenzofurans (PCDFs), dibenzo-p-dioxins (PCDDs) and to some extent biphenylenes (PCBPs) by high-resolution gas chromatography (HRGC) and mass spectrometry is described. Electron-impact (EI) and negative chemical ionization (NCI) mass spectrometry were used, and their application in environmental analyses documented. NCI shows increased sensitivity to all PCDFs and PCDDs except for 2,3,7,8- and other tetra-CDD isomers. The identification of the various PCDFs and PCDDs, specifically the identification of the toxic and hazardous 2,3,7,8-substituted isomers is emphasized; the unambiguous identification of all 2,3,7,8,-substituted PCDDs is documented. The application of HRGC and mass spectrometry to isomer-specific analyses of samples of aquatic species from the Baltic and the Great Lakes is shown. Results from this and previous studies indicate PCDF and PCDD residues in these organisms including significant levels of 2,3,7,8-substituted isomers. These aquatic species apparently show preferential retention or reduced metabolization rates for these toxic isomers. The results of samples from the Baltic indicate a contamination primarily due to PCDFs. The origin of this contamination seems complex and related to PCBs as well as chlorophenols. PCDF and PCDD isomer distribution patterns from analyses using HRGC and mass spectrometry aid in the identification of origin, sources and elucidation of routes of formation of these compounds. These methods are indispensable in taking measures to reduce future contaminations and to protect our environment.

Benzofurans↗
PubMed1985

Formation of polychlorinated dibenzofurans and dioxins during combustion, electrical equipment fires and PCB incineration.

Polychlorinated dibenzo-p-dioxins (PCDDs) and polychlorinated dibenzofurans (PCDFs) are likely formed by thermal synthesis of a variety of primary precursors. Highest levels of these compounds are expected, however, when the starting material requires only one or two reaction steps for their formation, as is the case with chlorophenols, chlorobenzenes and polychlorinated biphenyls (PCBs). Laboratory pyrolyses have indeed shown that PCBs give significant yields of PCDFs, and chlorobenzenes give both PCDFs and PCDDs. In addition, a variety of other chloroaromatic compounds are formed. From these experiments and from accidents involving PCB fires, it is known that PCDFs are the most important toxic compounds associated with PCBs. Most commercial PCBs contain PCDFs in the low ppm range. PCDF concentration does not increase during normal operation in electrical equipment. Accidents (fires and explosions) involving PCBs can give PCDF levels in soot of up to 1000 ppm and higher. Effective thermal destruction of PCB is possible in modern incineration units, provided high temperatures, excess air and sufficient residence times are used. Exact figures for minimum temperature and residence time cannot be given, since feedstock and incinerator construction greatly influence destruction efficiency. Effluents from EPA-licensed incinerators used for PCB destruction contain only very low levels of PCDDs and PCDFs.

Benzofurans↗
PubMed1986

Reproductive toxicology of disinfection by-products.

The chronic exposure of large segments of the population to disinfected drinking water has necessitated an evaluation of the health effects of the by-products of the chlorination process. This paper reviews the available information concerning the reproductive consequences associated with exposure to disinfection by-products. Four groups of compounds are discussed: the trihalomethanes, in particular chloroform; the chlorinated phenols; chlorinated humic substances; and the haloacetonitriles. In the pregnant female, chloroform and the 2- and 2,4-chlorophenols produced low levels of embryo- and fetotoxicity. Chloroform induced terata when administered by inhalation. The chlorinated humic substances and 2,4,6-trichlorophenol were without significant reproductive effects. The haloacetonitriles showed in utero toxicity, becoming more severe with increasing halogen substitution.

Acetonitriles↗
PubMed1998

Some aspects of the etiology of non-Hodgkin's lymphoma.

In epidemiologic studies, non-Hodgkin's lymphoma (NHL) has been associated with exposure to chemicals such as phenoxyacetic acids; chlorophenols; dioxins; organic solvents including benzene, polychlorinated biphenyls, chlordanes; and immunosuppressive drugs. Experimental evidence and clinical observations indicate that these chemicals may impair the immune system. The risk is increased for NHL in persons with acquired and congenital immune deficiency as well as autoimmune disorders. Also, certain viruses have been suggested to be of etiologic significance for NHL. In some cases of NHL the common mechanism for all these agents and conditions may be immunosuppression, possibly in combination with viruses.

Dioxins↗
PubMed2003

Measurement of beta-galactosidase tissue levels in a tumor cell xenograft model.

The nude mouse xenograft model is commonly used to examine the growth and development of human cancer cells in vivo. Tumor cells transfected with the Lac-Z reporter gene for beta-galactosidase (beta-gal) enzyme activity can be used to quantify tumor and metastatic development in this model. The present study was designed to develop methodology to accurately measure beta-gal in tumor and tissue samples from a nude mouse model. In this study, we developed tissue extraction procedures and compared the sensitivity and accuracy of o-nitrophenyl-beta-D-galactopyranoside (ONPG) and chlorophenol red beta-D-galactopyranoside (CPRG); two beta-gal substrates. Our results demonstrated that the CPRG substrate is more sensitive and accurate in the measurement of beta-gal activity than the ONPG substrate. In addition, matrices and blood in tissue samples are less likely to interfere with the CPRG assay. We concluded that the CPRG substrate-based assay represents a reliable technique for the determination of beta-gal activity in transfected cancer cells present in tumor and tissue specimens from the nude mouse xenograft model.

Animals↗
PubMed2006

Hemp (Cannabis sativa L.).

Hemp (Cannabis sativa L.) suspension culture cells were transformed with Agrobacterium tumefaciens strain EHA101 carrying the binary plasmid pNOV3635. The plasmid contains a phosphomannose isomerase (PMI) selectable marker gene. Cells transformed with PMI are capable of metabolizing the selective agent, mannose, whereas cells not expressing the gene are incapable of using the carbon source and will stop growing. Callus masses proliferating on selection were screened for PMI expression using a chlorophenol red assay. Genomic DNA was extracted from putatively transformed callus lines and the presence of the PMI gene was confirmed using polymerase chain reaction and Southern hybridization. Using this method, an average transformation frequency of 31.23% +/- 0.14 was obtained for all transformation experiments, with a range of 15.1 to 55.3%.

Agrobacterium tumefaciens↗
PubMed1984

Reagent for the enzymatic determination of serum total triglycerides with improved lipolytic efficiency.

A fully enzymatic assay is described for the determination of triglycerides. The coupled activities of triacylglycerol acylhydrolase and glycerol kinase result in the formation of glycerol-3-phosphate. The system also contains L-alpha-glycerol-phosphate oxidase, which produces hydrogen peroxide from glycerol-3-phosphate, and a sensitive chromogenic indicator system, consisting of peroxidase, 4-chlorophenol and 4-aminophenazone. We evaluated this method with respect to kinetics, linearity, blank rates, precision, accuracy, reagent stability and interfering substances. The accuracy of the triglyceride assay demands that each enzymatic reaction step be complete and homogeneous. We therefore developed HPTLC-1) and HPLC-2) methods to monitor the course and completeness of each step.

Chromatography, Liquid↗
PubMed1999

An ELISA for the H-subunit of human ferritin which employs a combination of rabbit poly- and mice monoclonal antibodies and an enzyme labeled anti-mouse-IgG.

We describe a sensitive ELISA for measuring the H-type subunit of human ferritin. A high detection sensitivity was attained by the use of antibodies from different species and an enzyme-conjugated secondary antibody. It consisted of a sandwich assay using a solid phase coated with a rabbit polyclonal antibody for human ferritin from term placenta and a soluble monoclonal antibody for human H-ferritin, followed by a secondary anti-mouse immunoglobulin (Ig)G conjugated to beta-galactosidase. The assay was calibrated with purified recombinant human H-ferritin from E. coli. The colorigenic chlorophenol red beta-D-galactopyranoside and the fluorogenic 4-methyl-umbelliferyl-beta-D-galactopyranoside substrates were used with similar outcome. The described method permits the measurement of human H-ferritin at a concentration ranging from 0.1 to 100 micrograms/l (or 20-20,000 pg per 200 microliters sample) and is accurate at a concentration as low as 0.3 microgram/l. The coefficient of variation of the assay was 6.05-10.3% and the recovery of H-ferritin added to cell lysates was 105.8 +/- 7.52%. Depending on the H-ferritin content of the cell line tested, only 600 to 60,000 cells of different human cell lines were needed to measure their H-ferritin content.

Animals↗
PubMed2003

Applications of recombinant Leishmania amazonensis expressing egfp or the beta-galactosidase gene for drug screening and histopathological analysis.

Leishmania amazonensis recombinants expressing the enhanced green fluorescent protein (egfp) gene or beta-galactosidase gene (lacZ) were constructed for drug screening and histopathological analysis. The egfp or lacZ in a leishmanial transfection vector, p6.5, was introduced into L. amazonensis promastigotes, and egfp or lacZ-carrying recombinant L. amazonensis, La/egfp and La/lacZ, respectively, were obtained. Expression of egfp or lacZ in both promastigotes and amastigotes could be clearly visualized by fluorescence microscopy or by light microscopy with 5-bromo-4-chloro-3-indolyl-beta-D-galactopyranoside (X-Gal), respectively. Fluorescence signal and beta-galactosidase activity measured by a colorimetric reaction with chlorophenol red beta-D-galactopyranoside (CPRG) were well correlated to the numbers of these parasites. The inhibitory concentration (IC50) of a leishmanicidal drug, amphotericin B, in L. amazonensis promastigotes measured using La/egfp and La/lacZ was similar to that measured by conventional methods such as cell counting, thymidine incorporation and colorimetric assay. Furthermore, the fluorescence signal and absorbance of CPRG correlated well with the numbers of La/egfp and La/lacZ amastigotes in macrophages, respectively, suggesting La/egfp and La/lacZ can be a convenient and useful tool for drug screening not only in promastigotes, but also in amastigotes of L. amazonensis. La/lacZ collected from mouse tissues four weeks after the parasite infection were stained well with X-Gal. La/lacZ allowed parasite detection at high sensitivity in the tissues of infected mice and will be useful for following infections in macrophages in vivo. Thus, the marker-transfected Leishmania parasites constructed in this study will be useful for analyses of Leishmania parasites, especially at the intracellular stage.

Animals↗
PubMed1991

[Identification of urinary metabolites in a patient of acute poisoning by p-chloroaniline].

In order to clarify urinary metabolites of p-chloroaniline (p-CA), urine samples of a patient acutely poisoned with p-CA were analyzed by gas chromatography/mass spectrometry. Urinary metabolites were extracted with diethylether at pH 1.0 and pH 10 from urine samples hydrolyzed with acid and base and from intact urine samples. Aliquots of the ethereal extracts were injected into the gas chromatography, and p-CA and its metabolites were identified by comparing their mass spectra and retention times to those of standards. Six substances identified were as follows: p-CA, 2-amino-5-chlorophenol, 2,4-dichloroaniline, p-chloroformanilide and traces of p-chloroacetanilide and 4-chloro-2-hydroxyacetanilide. Since p-CA was mainly detected in the hydrolyzed urine samples, p-CA was considered to form conjugates in the urine. N-Acetylation reactions of p-CA were suggested to be weak in human, because extremely minute amounts of p-chloroacetanilide and 4-chloro-2-hydroxyacetanilide were detected in the urine.

Adult↗
PubMed1994

[Structure-activity relationships of organic solvents and related chemicals].

The number of chemicals used in industry is increasing, and as a consequence workers in chemical industries are thought to have many opportunities for being exposed to chemicals. For organic solvents, although a number of studies have shown the toxicity of individual chemicals, there are a relatively small number of studies that have described their toxicity in terms of a quantitative structure-activity relationship (QSAR). In the present article I first introduced an outline of the method of QSAR (Hansch's method), and then reviewed the literature on QSAR of industrial chemicals, principally organic solvents and related chemicals as follows: 1) A review was made of the studies of general toxicity of chlorophenols, alcohols, amines, anilines, phenols, ethers, alkanes, ketones, acrylates, methacrylates and nitriles. In almost all cases, the general toxicity is related to log P, in which P is n-octanol/water partition coefficient, indicating the importance of the hydrophobicity of chemicals for their toxicities. 2) The QSARs of anesthetic organic solvents were reviewed. The chemicals analysed were ethers, alkanes, ketones, miscellaneous chemicals and anesthetic gases. It is shown that the relative anesthetic potency of anesthetic gases depends not only on the hydrophobicity expressed by log P but on a polar factor, while the potency of other chemicals depends largely on log P. 3) The relationship of the structure of organic solvents to skin penetration or absorption was reviewed. QSARs reveal that the potency of skin penetration or absorption of solvents is a function of water solubility, log P or hydrogen bond number, each relating to hydrophobicity. 4) Some organic solvents have an effect on the upper respiratory tract. The established QSAR models considerably resemble corresponding equations for gas/liquid partition coefficients into organic bases such as tricresylphosphate. 5) The ecotoxicity of chemicals including solvents was reviewed. Overall, the relative toxic potency of chemicals is related linearly to log P, indicating the importance of hydrophobicity in determining the toxicity of chemicals. 6) Although no QSAR has modeled the mutagenic activity of organic solvents, a few studies show the relationship between the structure and mutagenicity of haloalkenes. Finally, if QSAR could model the toxicity of a series of chemicals, it would serve our purpose of understanding the mechanism of toxicity and of predicting the toxic potency of chemicals in the same series tested.

Solvents↗
PubMed2002

Effects of high temperature and disinfectants on the viability of Sarcocystis neurona sporocysts.

The effect of moist heat and several disinfectants on Sarcocystis neurona sporocysts was investigated. Sporocysts (4 million) were suspended in water and heated to 50, 55, 60, 65, and 70 C for various times and were then bioassayed in interferon gamma gene knockout (KO) mice. Sporocysts heated to 50 C for 60 min and 55 C for 5 min were infective to KO mice, whereas sporocysts heated to 55 C for 15 min and 60 C or more for 1 min were rendered noninfective to mice. Treatment with bleach (10, 20, and 100%), 2% chlorhexidine, 1% betadine, 5% o-benzyl-p-chlorophenol, 12.56% phenol, 6% benzyl ammonium chloride, and 10% formalin was not effective in killing sporocysts. Treatment with undiluted ammonium hydroxide (29.5% ammonia) for 1 hr killed sporocysts, but treatment with a 10-fold dilution (2.95% ammonia) for 6 hr did not kill sporocysts. These data indicate that heat treatment is the most effective means of killing S. neurona sporocysts in the horse feed or in the environment.

Animal Feed↗
PubMed1988

Effect of phenol and halogenated phenols on energy transfer reactions of rat liver mitochondria.

The in vitro effects of phenol and p-halogenated phenols on mitochondrial energy transfer reactions were examined using isolated rat liver mitochondria. The relationship between physiochemical properties of phenolic compounds and their effects on mitochondria were studied. Phenol and p-halogenated phenols induced the release of K+ ions from mitochondria, suggesting a change in permeability to K+ ions. A decrease in the respiratory control index, an increase in K+ release and stimulation of latent ATPase activity were observed with these compounds in the descending order of p-iodophenol, p-bromophenol, p-chlorophenol, p-fluorophenol and phenol. The concentrations of the phenolic compounds resulting in fifty percent inhibition of the respiratory control index and those resulting in fifty percent release of K+ ions significantly correlated with Hammett's substituent constant (sigma) and the hydrophobic binding constant (pi) of the compounds.

Adenosine Triphosphatases↗
PubMed2003

Similarities in bioaccumulation patterns of polychlorinated dibenzo-p-dioxins and furans and polychlorinated diphenyl ethers in laboratory-exposed oligochaetes and semipermeable membrane devices and in field-collected chironomids.

Sediment and chironomid samples were collected from a river in the vicinity of and downstream from a closed chlorophenol production plant, and they were analyzed for polychlorinated dibenzo-p-dioxins and furans (PCDD/F) and polychlorinated diphenyl ethers (PCDE). Bioaccumulation of these compounds from the sediments by the oligochaeta, Lumbriculus variegatus, and semipermeable membrane devices (SPMDs) was studied in a 28-d bioaccumulation test. The sum concentrations of PCDD/Fs and PCDEs in sediments varied spatially, peaking at the site below the production plant, but the congener composition remained fairly constant throughout the river. The sum concentrations of chironomids, oligochaetes, and SPMDs all varied independently of sediment concentrations. Both invertebrates accumulated more PCDEs, whereas PCDD/Fs dominated in sediments and SPMDs. Despite the variable sum concentrations, similarities were observed in concentrations and compositions of individual congeners. A significant correlation was found between sediments and oligochaetes, and between oligochaetes and chironomids, for both PCDD/Fs and PCDEs. These results suggest that bioaccumulation of PCDD/Fs and PCDEs in invertebrates is nonselective. Furthermore, the laboratory bioaccumulation tests seem to yield relevant results. The SPMDs were found to give good predictions of the PCDD/F concentrations of sediments and oligochaetes. For PCDEs, the estimates were slightly poorer, but still useful for preliminary concentration assessments.

Animals↗
PubMed2005

Contaminant accumulation and biomarker responses in caged fish exposed to effluents from anthropogenic sources in the Karnaphuly River, Bangladesh.

The possible ecotoxicological effects of a paper and pulp mill effluent were investigated by measuring selected contaminants and biomarkers in caged Nile tilapia (Oreochromis niloticus) and sharptooth catfish (Clarias gariepinus) from the Karnaphuly River, Bangladesh. Fish were caged for 28 d at two upstream reference sites (2 and 4 km) and four downstream sites (3, 5, 8, and 12 km) from the effluent outlets. Organochlorine contaminants and bile biomarkers were bioaccumulated to higher levels at downstream polluted sites than at the reference sites, including hexachlorobenzene (HCB), hexachlorocyclohexane (HCH), polychlorinated biphenyls (PCBs) in liver, and chlorophenolic compounds like 2,4-dichlorophenol and 2,4,6-trichlorophenol in bile. Levels of glucose, protein, and aspartate aminotransferase were analyzed in plasma, whereas cytochrome P4501A (CYP1A) levels were determined in S-12 supernatants of liver. The results, including CYP1A induction and bile biomarkers, clearly indicated that, in addition to the paper and pulp mill effluents, the downstream sites appear to receive other inputs of contaminants. This field assessment in a Bangladeshi river demonstrates biomarker measurements in caged fish as a promising approach for evaluating accumulation and effects of industrial effluents in fish of developing countries.

Animals↗