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PubMed2006

Ecotoxicological evaluation of sodium fluoroacetate on aquatic organisms and investigation of the effects on two fish cell lines.

Sodium monofluoroacetate (compound 1080) is one of the most potent pesticides. It is also a metabolite of many other fluorinated compounds, including anticancer agents, narcotic analgesics, pesticides or industrial chemicals. Other sources of water contamination are the atmospheric degradation of hydrofluorocarbons and hydrochlorofluorocarbons. However, there is little information available about the adverse effects of sodium fluoroacetate in aquatic organisms. Firstly, the bacterium Vibrio fischeri (decomposer), the alga Chlorella vulgaris (1st producer) and the cladoceran Daphnia magna (1st consumer) were used for the ecotoxicological evaluation of SMFA. The most sensitive models were C. vulgaris and D. magna, with a NOAEL of 0.1 and an EC50 of 0.5 mM at 72 h, respectively. According to the results after the acute exposure and due to its high biodegradation rate and low bioaccumulation potential, sodium fluoroacetate is most unlikely to produce deleterious effects to aquatic organisms. Secondly, two fish cell lines were employed to investigate the effects and mechanisms of toxicity in tissues from 2nd consumers. The hepatoma fish cell line PLHC-1 was more sensitive to SMFA than the fibroblast-like fish cell line RTG-2, being the uptake of neutral red the most sensitive bioindicator. Lysosomal function, succinate dehydrogenase and acetylcholinesterase activities were inhibited, glucose-6-phosphate dehydrogenase activity was particularly stimulated, and metallothionein and ethoxyresorufin-O-deethylase levels were not modified. Intense hydropic degeneration, macrovesicular steatosis and death mainly by necrosis but also by apoptosis were observed. Moreover, sulphydryl groups and oxidative stress could be involved in PLHC-1 cell death induced by SMFA more than changes in calcium homeostasis.

Acetylcholinesterase↗
PubMed1991

The phenomenon of separate intra- and extracellular resonances of difluorophosphate in 31P and 19F NMR spectra of erythrocytes.

Trifluoroacetate and trifluoroacetamide, when added to a suspension of human red blood cells, give rise to separate 19F NMR signals from the intra- and extracellular species. This phenomenon has recently been exploited for measuring the membrane potential of erythrocytes. However, the separation of the peaks was incorrectly ascribed to a difference in magnetic susceptibility between the intra- and extracellular environments. Previously, we have reported well-resolved resonances in 31P NMR spectra for the intra- and extracellular populations of some phosphoryl compounds; in these cases, however, the intracellular peak is shifted to low frequency which is the opposite to the situation with the fluorinated compounds. By using difluorophosphate, which rapidly equilibrates across the membrane of human erythrocytes and which has both the phosphoryl and fluorine functional groups, we observed the separate intra- and extracellular resonances. But, the intracellular resonance was shifted to high frequency of the extracellular resonance in the 19F spectra and to low frequency in the 31P spectra. The basis for the phenomenon in both cases is thought to be the reduced hydrogen bonding inside the cells between the solvent water and the phosphoryl oxygen or fluorine atoms.

Erythrocytes↗
PubMedDate not supplied

Perfluorocarbon temperature measurements using 19F NMR.

Measuring the T1 of the fluorine resonances of perfluorocarbons (PFC) is a unique method for monitoring oxygen tension in vivo. However, because T1 is also temperature sensitive, error in the pO2 determination due to animal-to-animal temperature variation may arise. Pathophysiologic conditions, such as ischemia, where temperature is not known a priori may also introduce error. Thus, measuring the PFC temperature is clearly desirable in order to correct for tissue temperature variations during the pO2 determination. Because the fluorine chemical shift of various fluorinated compounds has a significant temperature dependence, we evaluated the effect of temperature on the chemical shift of the fluorine resonances of perfluorotributylamine (FTBA). A linear relationship was found between chemical shift and temperature in vitro. In addition, the relative FTBA chemical shifts were essentially independent of pO2. Chemical shift temperature measurements in vivo, obtained from a 10 microL FTBA bubble in the preretinal vitreous space of the rabbit eye, were in good agreement (+/- 0.5 degrees C) with thermocouple measurements from the same location. Good agreement between the NMR determined temperature and core body temperature was also found. The implication of such temperature measurements for the ultimate accuracy of the pO2 determination based on PFC T1 measurements is discussed. To the best of our knowledge, this report describes the first absolute temperature measurement in vivo by NMR.

Animals↗
PubMedDate not supplied

Induction of apoptosis by sodium fluorosilicate treatment in human osteogenic sarcoma (HOS) cells.

Fluorine compounds are widely used for the prevention of caries, and recently sodium fluorosilicate has been used in water fluorination. The cytotoxic effects of sodium fluorosilicate in several osteosarcoma and oral cancer cells were evaluated in this study by measurement of inhibition of cell proliferation. Human osteogenic sarcoma (HOS) cells were the most sensitive to sodium fluorosilicate treatment. Induction of apoptosis, such as nucleosomal DNA fragmentation and the appearance of apoptotic bodies, were observed in HOS cells by agarose gel electrophoresis and by flow cytometric analysis, respectively. The molecular mechanism of apoptosis induction in HOS was investigated by Western blot analysis. The level of Bcl-2 was decreased and consequent release of cytochrome c was increased. Caspase-3 was activated and the cleavage of poly (ADP-ribosyl) polymerase was increased. In conclusion, sodium fluorosilicate induces apoptosis in HOS cells through decrease in Bcl-2, the release of cytochrome c to the cytosol and activation of caspase-3.

Apoptosis↗
PubMed2005

Syntheses, biological evaluation, and molecular modeling of 18F-labeled 4-anilidopiperidines as mu-opioid receptor imaging agents.

The synthesis, evaluation, and molecular modeling of a series of 18F-labeled 4-anilidopiperidines with high affinities for the mu-opioid receptor (mu-OR) are reported. On the basis of the high brain uptake and selective retention in brain regions that contain a high concentration of the mu-OR, combined with a good metabolic stability, [18F]fluoro-pentyl carfentanil ([18F]4) and 2-(+/-)[18F]fluoropropyl-sufentanil ([18F]6) were selected as the lead compounds for further evaluation. The binding affinity to the human mu-OR was 0.74 and 0.13 nM for [18F]4 and [18F]6, respectively. In vitro autoradiography of [18F]4 and [18F]6 on rat brain sections produced patterns in accordance with the known distribution of mu-OR expression. Structure-activity relationships of the fluorinated compounds are discussed with respect to the interaction with an activated-state model of the mu-OR. Taken together, the in vivo and in vitro data indicate that [18F]4 and [18F]6 hold promise for studying the mu-opioid receptor in humans by means of positron emission tomography.

Aniline Compounds↗
PubMed2006

Enantioselective synthesis of an all-syn four vicinal fluorine motif.

Alkanes bearing multiple vicinal fluorine atoms at adjacent stereocenters may be considered intermediate between alkanes and perfluoroalkanes, and as a class, their chemistry and behavior remain to be explored. We report here a stereoselective synthesis of an all-syn four vicinal fluorine motif as a single enantiomer. The four vicinal fluorine compound was amenable to single-crystal X-ray analysis, and the resulting structure displays gauche relationships between all four fluorines, consistent with the fluorine gauche effect, and CF...HC hydrogen bonding between adjacent fluoroalkyl chains.

Crystallography, X-Ray↗
PubMed1993

Fluorinated probes to measure carboxylesterase activities using 19F NMR spectroscopy: application to erythrocytes and Helicobacter pylori.

Eight fluorinated compounds were tested as putative probes to measure carboxylesterase activity employing 19F nuclear magnetic resonance spectroscopy. The method takes advantage of the sensitivity of fluorine resonances to the changes in the chemical bonding in the covalent structures where they are located. Determination of the kinetic parameters of ethyl fluoroacetate and diethyl fluoromalonate in hemolysates showed that these probes were well suited to study carboxylesterase activities in complex systems the potential of these probes for noninvasive applications was demonstrated in measurements of carboxylesterase kinetic parameters in intact erythrocytes. The presence of carboxylesterases was established in several strains of the bacterium Helicobacter pylori employing 19F nuclear magnetic resonance spectroscopy, and the kinetic parameters of these enzymes for ethyl fluoroacetate and diethyl fluoromalonate were measured.

Animals↗
PubMed1987

Proton decoupled fluorine nuclear magnetic resonance spectroscopy in situ.

The efficacy of proton decoupling for enhancing the 19F nuclear magnetic resonance (NMR) signal-to-noise ratio and spectral resolution in the intact subject is demonstrated. A geometrically orthogonal cross-coil antenna configuration (Helmholtz pair, surface coil) is employed to provide 40 dB of isolation between the 19F observe and 1H decouple frequencies of 188 and 200 MHz, respectively. Further isolation is achieved through the use of high-quality notch filters on both observation and decoupling channels. Application of 19F-(1H) NMR spectroscopy to the study of 2-fluoro-2-deoxy-D-glucose metabolism in cerebral tissue in situ is presented. Significant improvements in sensitivity and resolution are obtained and result from both a collapse of the JFH multiple structure and a substantial positive nuclear Overhauser effect (NOE). To our knowledge, this is the first such demonstration of 1H decoupling in conjunction with 19F observation for study of the metabolism of a fluorinated compound in the living subject.

Animals↗
PubMed2005

Total toxicity equivalents emissions of SF6, CHF3, and CCl2F2 decomposed in a RF plasma environment.

Sulfur hexafluorine compound (SF6), trifluoromethane (CHF3) and diclorodifluoromethane (CCl2F2) are extensively used in the semiconductor industry. They are global warming gases. Most studies have addressed the effective decomposition of fluorine compounds, rather than the toxicity of decomposed by-products. Hence, the concepts of toxicity equivalents (TEQs) were applied in this work. The results indicated that HF and SiF4 were the two greatest contributors of TEQ to the SF6/H2/Ar plasma system, while F2 and SiF4 were the two greatest contributors to the SF6/O2/Ar system. Additionally, SiF4 and HF were the two greatest contributors of TEQ to both the CHF3/H2/Ar and CHF3/O2/Ar plasma systems. HF and HCl were the two greatest contributors of TEQ to the CCl2F2/H2/Ar plasma system, and Cl2 and COCl2 were the two greatest contributors to the CCl2F2/O2/Ar system. HCl and HF can be recovered using wet scrubbing, which reduces the toxicity of these emission gases. Consequently, the hydrogen-based plasma system was a better alternative for treating gases that contained SF6, CHF3 and CCl2F2 from the TEQs point of view.

Air Pollutants↗
PubMed1981

Organic compounds near dumpsites in Niagara Falls, New York.

Water and sediment samples were taken from sites adjacent to hazardous waste disposal areas in Niagara Falls, New York. The samples were analyzed by gas chromatographic mass spectrometry. The following compounds were identified: chlorobenzenes, chlorotoluenes, polycyclic aromatic hydrocarbon derivatives, cyclohexane derivatives, polychlorinated biphenyls, trichlorophenol and other phenols, benzotrifluorides, mirex and phenothiazine. A large number of benzyl derivatives and unusual fluorinated compounds were also found; they were probably waste by-products of industrial chemical production. The hazardous waste disposal sites were probably the major sources for most of the compounds.

Gas Chromatography-Mass Spectrometry↗
PubMed2004

PET imaging of amyloid in Alzheimer's disease.

Alzheimer's disease (AD) is the most common form of dementia and is characterised by progressive impairment in cognitive function and behaviour. The pathological features of AD include neuritic plaques composed of amyloid-beta peptide (Abeta) fibrils, neurofibrillary tangles of hyperphosphorylated tau, and neurotransmitter deficits. Increases in the concentration of Abeta in the course of the disease with subtle effects on synaptic efficacy will lead to gradual increase in the load of amyloid plaques and progression in cognitive impairment. Direct imaging of amyloid load in patients with AD in vivo would be very useful for the early diagnosis of AD and the development and assessment of new treatment strategies. Three different strategies are being used to develop compounds suitable for in vivo imaging of amyloid deposits in human brains. Monoclonal antibodies against Abeta and peptide fragments have had limited uptake by the brain when tested in patients with AD. When putrescine-gadolinium-Abeta has been injected into transgenic mice overexpressing amyloid, labelling has been observed with MRI. The small molecular approach for amyloid imaging has so far been most successful. The binding of different derivatives of Congo red and thioflavin has been studied in human autopsy brain tissue and in transgenic mice. Two compounds, fluorine-18-labelled-FDDNP and carbon-11-labelled-PIB, both show more binding in the brains of patients with AD than in those of healthy people. Additional compounds will probably be developed that are suitable not only for PET but also for single photon emission CT (SPECT).

Alzheimer Disease↗
PubMed1984

[Kinetics of fluorine elimination in exposed workers].

The fourteen-day kinetics of fluorine (F) elimination in urine was followed up in 24 operators from three main workshops of the plant for phosphorous fertilizers. The concentration of F in urine was determined at the beginning, by 6th h and during the last two hours of a working shift in four successive days and at the beginning of the following production cycle after the discontinuation of the exposure. In parallel, the gas-like fluorine compounds in the air of working environment was also determined. Analogous investigations were performed with a control group--30 non-exposed workers. A potentio-metric method with fluorine-selective electrode was used for the determination of F content in urine and the concentration of the gas-like fluorides in the air. A well manifested tendency to increased excretion was established by the end of the working shift and in the course of the working cycle. The data on the rate of fluorine elimination show that it is the highest during the last two exposure hours, most manifested in the workers from the workshop TSP, less-in the workshop PhA and least--in the workshop NTPP. The concentration of fluorine ions in urine for the three groups of workers investigated, was increased as compared with control values, both by 6th h and during the last two hours.

Bulgaria↗
PubMed2007

Bond orders and atomic properties of the highly deformed halogenated fullerenes C60F18 and C60Cl30 derived from their charge densities.

The experimental charge densities of the halogenated C(60) fullerenes C(60)F(18) and C(60)Cl(30) were determined from high-resolution X-ray data sets measured with conventional Mo(Kalpha) radiation at 20 K for C(60)Cl(30) and with synchrotron radiation at 92 K for the fluorine compound. Bond topological and atomic properties were analyzed by using Bader's AIM theory. For the different C--C bonds, which vary in lengths between 1.35 and 1.70 A bond orders n between n=2 and significantly below n=1 were calculated from the bond topological properties at the bond critical points (BCP's). The low bond orders are seen for 5/6 bonds with each contributing carbon carrying a halogen atom. By integration over Bader's zero flux basins in the electron density gradient vector field atomic properties were also obtained. In contrast to free C(60), in which all carbon atoms have a uniform volume of 11 A(3) and zero charge, atomic volumes vary roughly between 5 and 10 A(3) in the halogenated compounds. Almost zero atomic charges are also found in the Cl derivative but a charge separation up to +/-0.8 e exists between C and F in C(60)F(18) due to the higher fluorine electronegativity, which is also seen in the electrostatic potential for which the electronegativity difference between carbon and fluorine, and the addition to one hemisphere of the fullerene cage leads to a strong potential gradient along the C(60)F(18) molecule. From the summation over all atomic volumes it follows that the halogen addition does not only lead to a dramatic distortion of the C(60) cage but also to a significant shrinkage of its volume.

Journal Article↗
PubMed2000

Development of an 19F NMR method for the analysis of fluorinated acids in environmental water samples.

This investigation was carried out to evaluate 19F NMR as an analytical tool for the measurement of trifluoroacetic acid (TFA) and other fluorinated acids in the aquatic environment. A method based upon strong anionic exchange (SAX) chromatography was also optimized for the concentration of the fluoro acids prior to NMR analysis. Extraction of the analyte from the SAX column was carried out directly in the NMR solvent in the presence of the strong organic base, DBU. The method allowed the analysis of the acid without any prior cleanup steps being involved. Optimal NMR sensitivity based upon T1 relaxation times was investigated for seven fluorinated compounds in four different NMR solvents. The use of the relaxation agent chromium acetylacetonate, Cr(acac)3, within these solvent systems was also evaluated. Results show that the optimal NMR solvent differs for each fluorinated analyte. Cr(acac)3 was shown to have pronounced effects on the limits of detection of the analyte. Generally, the optimal sensitivity condition appears to be methanol-d4/2M DBU in the presence of 4 mg/mL of Cr-(acac)3. The method was validated through spike and recovery for five fluoro acids from environmentally relevant waters. Results are presented for the analysis of TFA in Toronto rainwater, which ranged from < 16 to 850 ng/L. The NMR results were confirmed by GC-MS selected-ion monitoring of the fluoroanalide derivative.

Air Pollutants↗
PubMed1978

A sensitive analytical method for pyrrolizidine alkaloids. The mass spectra of retronecine derivatives.

The pyrrolizidine alkaloids in Senecio jacobaea can be hydrolyzed to the common base, retronecine, and derivatized to form the bistrifluoroacetate, bisheptafluorobutyrate, diacetate and bistrimethylsilyl ether. The analysis of the fluorinated compounds by electron capture provides sensitivity for detection of these alkaloids. The bond weakening effect in the ion formed on electron impact, between the allylic carbon and alkyl ester oxygen due to the electron withdrawing fluorinated groups of the ester, changes the driving force for fragmentation from the nitrogen alpha-cleavage reaction to a charge site migration. This yields alkyl-oxygen bond cleavage and formation of a stabilized allylic cation which is the base peak.

Chromatography, Gas↗
PubMed2003

Differential substituent effects of beta-halogens in water-soluble porphyrins.

The first water-soluble beta-octafluorinated porphyrins, 5,10,15,20-tetrakis(4-sulfonatophenyl)-2,3,7,8,12,13,17,18- octafluoroporphyrin, 1, and 5,10,15,20-tetrakis(2,6-difluoro-3-sulfonatophenyl)-2,3,7,8,12,13,17,18- octafluoroporphyrin, 2, have been prepared and their aqueous aggregation, acid-base, and optical properties have been characterized. The porphyrins are tetraanionic at neutral pH (at pH = 3-11 for 1 and pH = 0-9 for 2). Semiempirical (AM1) calculations provide evidence that somewhat unusual acidity characteristics of the fluorinated compounds (with respect to similar brominated porphyrins) can be rationalized solely on the basis of chemical hardness and electronegativity arguments. These results indicate that the large conformational differences seen in the structures of brominated and fluorinated water-soluble porphyrins have little impact upon N-H acidity. Metalation of 1 and 2 with ZnCl2 yielded the zinc complexes, which were characterized by optical spectroscopy and electrochemistry.

Journal Article↗
PubMed2004

[Living conditions of deer in the provinces of Western Pomerania and Lubuskie as revealed by mandibular content of fluoride, calcium and magnesium. II. Detailed statistical analysis with the statistica neural networks software].

Animals from areas contaminated by industrial emissions containing fluoride may accumulate it predominantly in hard tissues. The stable composition of the mandible makes it suitable for the study of accumulation of fluorides and other elements (Mg, Ca). It is also possible to determine the extent of pollution with fluorine compounds around industrial plants and to reveal some of the features of the natural habitat of wild animals. We applied the advanced technique of neural networks to investigate the simultaneous influence of multiple parameters on the accumulation of fluorine, magnesium, and calcium in the mandible of deer and possible interactions between these elements. The first step involved the generation of a neural network. In the present work, networks were created with the Intelligent Problem Solver (IPS). Input data were divided into three sets. One was used for training (Tr) of the network, another for validation (Ve) and control over the training process and the last one for testing (Te). Network quality was checked with the following parameters: Data Mean--average value of variable; Data SD--standard deviation of variable; Error Mean--average value of error; Abs. Mean--average error modulus; Error SD--standard deviation of error; SD Ratio--ratio of standard deviation of error to standard deviation of variable (Error SD/Data SD); Correlation--Pearson's correlation coefficient. For the model to be satisfactory, Pearson's correlation coefficient should be close to 1. In the case of complex problems with an unclear influence of parameters on the process, an analysis of parametric sensitivity must be performed. This task was accomplished automatically with the computer program. It was found that the effect of the same parameters on the accumulation of fluorine, magnesium and calcium varied. The results suggest interactions between the examined elements.

Animals↗
PubMed1980

Mutagenicity of 2- and 3-carbon halogenated compounds in the Salmonella/mammalian-microsome test.

Short-chain, 2- and 3- carbon halogenated hydrocarbons were tested for mutagenicity for Salmonella typhimurium strain TA 100 both with and without the presence of S-9. Without exception, all brominated derivatives were more mutagenic than the chlorinated derivatives, usually by a substantial order of magnitude. 2-Fluoroethanol, the only fluorinated compound tested, showed little or no mutagenic activity up to 100 micromole per plate concentration. Two highly purified propane derivatives containing a halogen atom on each of the three carbons showed little or no direct mutagenic activity. A third trihalogenated compound with a halogen atom on each carbon atom showed some direct mutagenic activity, probably due to impurities. However, all three trihalogenated compounds were highly active mutagens following S-9 activation. The presence of a double bond in the case of 1, 2, 3-trichloropropene resulted in a higher level of direct mutagenic activity than 1, 2, 3-trichloropropane, but activation with S-9 resulted in a further increase in mutagenic activity with the former compound. On the other hand, S-9 caused a substantial decrease in mutagenic activity of most compounds containing a double bond. With the presence of an alcoholic group in a compound, the addition of S-9 caused variable responses, increasing the number of his+ revertant colonies due to 2, 3-dibromopropanol but had little or no effect with five other compounds containing an alcoholic group. Evidence is also presented that the position of a double bond in relation to the halogen atoms may influence mutagenic activity.

Biotransformation↗