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At least 721 records · Page 40Linked to original sources
PubMed1992

Subretinal perfluorocarbon liquids. An experimental study.

Perfluorocarbon liquids (PFCL) are fully fluorinated, synthetic, transparent compounds with a high specific gravity. These compounds are being increasingly used as an intraoperative tool for repair of complicated retinal detachments. A known complication of their use, however, is liquid entering the subretinal space via a retinal break. The purpose of this study was to evaluate the effects of two of these liquids when placed subretinally in the rabbit eye. Vitrectomy, retinotomy, and subretinal injection of 0.03 cc of either perfluoroctane, perfluorotributylamine, or balanced salt solution (control eyes) were performed on 36 rabbit eyes. Animals were monitored clinically by indirect ophthalmoscopy and fundus photography for up to 21 days. After the 21-day observation period, electroretinograms (ERG) were taken before the rabbits were killed. Histopathologic studies were done at 3 hours, 24 hours, 3 days, 7 days, 14 days, and 21 days after injection. Three eyes demonstrated tearing of the retinotomy site due to downward migration of the PFCL droplet. Results of the ERGs were normal in all animals tested. Phagocytosis of PFCL droplets by the retinal pigment epithelium (RPE) was observed in 1 eye 3 hours after injection. Three of the eyes that received PFCL injections and all of the control eyes demonstrated moderate intracellular edema of both inner and outer nuclear layers as early as 24 hours after injection. In one eye injected with PFCL, these changes progressed to swelling and cystic formation of the inner nuclear layer and mild degeneration of the outer photoreceptor segments 3 days after injection. It was assumed that these effects occurred on a mechanical basis and were not related to PFCL toxicity.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1988

Effect of recent antibacterial agents against bacteria causing diarrhoea.

The susceptibility of 424 bacterial isolates causing diarrhoea were tested by agar dilution technique on Mueller-Hinton Agar against amoxicillin, ampicillin, ceftriaxone, chloramphenicol, co-trimoxazole, ciprofloxacin, doxycycline, norfloxacin and ofloxacin. The bacterial species included were Aeromonas hydrophila, Edwardsiella tarda, Pleisomonas shigelloides, Salmonella spp., Shigella spp., Vibrio cholerae and Vibrio parahaemolyticus. The most active compounds were the fluorinated 4-quinolones studied, that is, ciprofloxacin, norfloxacin and ofloxacin, and ceftriaxone. The other antibacterial agents were considerably less active; a substantial portion of tested isolates were resistant to them.

4-Quinolones↗
PubMed1985

[Duration and course of pregnancy in women living in the region of the Police Chemical Plant (clinical data)].

In view of expected detrimental effects of fluorine and its compounds on pregnant women's organism, the duration and course of pregnancies have been compared in the "Police" Chemical Plant and control group. Immature deliveries and necrosed pregnancies in the "Police" Chemical Plant women were observed, though with no statistical characterisation. Perhaps the analysis of more ample material would indicate characteristic differences.

Abortion, Spontaneous↗
PubMed2003

Crystallization and X-ray diffraction of 5'-fluoro-5'-deoxyadenosine synthase, a fluorination enzyme from Streptomyces cattleya.

Organofluorine compounds are widely prepared throughout the chemicals industry, but their prepararion generally requires harsh fluorinating reagents and non-aqueous solvents. On the other hand, biology has hardly exploited organofluorine compounds. A very few organisms synthesize organofluorine metabolites, suggesting they have evolved a mechanism to overcome the kinetic desolvation barrier to utilizing F(-)(aq). Here, the purification and crystallization of an enzyme from Streptomyces cattleya which is responsible for the synthesis of the C-F bond during fluoroacetate and 4-fluorothreonine biosynthesis is reported. The protein crystallizes in space group C222(1), with unit-cell parameters a = 75.9, b = 130.3, c = 183.4 A, alpha = beta = gamma = 90 degrees. Data were recorded to 1.9 A at the ESRF. The structure of the protein should provide important insights into the biochemical process of C-F bond formation.

Bacterial Proteins↗
PubMed1999

Playing the Keyboard of Fluorine Chemistry(,).

Organometallic fluorides of main group and transition elements are described starting with monocyclopentadienyl derivatives of the group 4 metals and their adducts with AlMe(3). Host-guest type compounds such as [(eta(5)-C(5)Me(4)Et)TiF(3)](4)CaF(2) and supramolecular assemblies such as Ag(S(4)(CN)(2))(2)AsF(6) are also observed. Finally some aluminum-fluorine compounds including derivatives of aluminum(I) are described.

Journal Article↗
PubMed2002

New method of fluorination using potassium fluoride in ionic liquid: significantly enhanced reactivity of fluoride and improved selectivity.

We have found the new nucleophilic fluorination reaction of some halo- and mesylalkanes to the corresponding fluoroalkanes with KF in the presence of [bmim][BF4] under various reaction conditions. 2-(3-Methanesulfonyloxypropoxy)naphthalene (1) was used as a model compound to optimize this fluorination reaction. Whereas the fluorination of the mesylate 1 with KF in an organic solvent such as CH3CN at 100 degrees C occurred hardly even after 24 h, the same reaction in ionic liquids, [bmim][BF4], as a reaction solvent was completed within 1.5 h, affording the wanted product 2-(3-fluoropropoxy)naphthalene 2a (85%) together with the alkene byproduct 2c (10%). Very interestingly, however, the addition of water (5 equiv) completely eliminated the formation of the undesired alkene 2c and thus gave higher yield of 2a (92%, entry 2). The use of acetonitrile as a cosolvent did not affect the reactivity of the fluorination. The presence of a proper amount of cosolvent was rather desirable (94% yield of 2a). We performed fluorination reactions with other ionic liquids ([bmim][PF6], [bmim][SbF6], [bmim][OTf], and [bmim][N(Tf)2], and two other cosolvents, to find the optimal ionic liquid and cosolvent. Nine different compounds were examined, including the 10 g-synthesis of 2-(fluoromethyl)naphthalene in 93% of isolated yield.

Chemistry, Organic↗
PubMed1994

Synthesis of the fluorine-18 labeled inhalation anesthetics.

Fourteen compounds (fluoroalkanes and fluoroethers), including the two most utilized inhalation anesthetics Isoflurane (CF3CHClOCF2H) and Halothane (CF3CHBrCl), have been labeled with fluorine-18 via a facile 18F-for-19F exchange reaction. The compounds include ten inhalation anesthetics which span a ten-fold range in potency and four structurally related non-anesthetics. All the compounds possess a trifluoromethyl group (CF3) adjoining a carbon atom with an acidic alpha-hydrogen and at least one halogen or a strong electron withdrawing group (X), [CF3CHXR]. We postulate the isotopic fluoride exchange reaction proceeds through a carbanion transition state resulting from alpha-proton transfer to base. The carbanion stability is attributed to the inductive effect of the CF3 group and the electron withdrawing capability of X. Compounds labeled in dimethyl sulfoxide (DMSO) at 125 degrees C in 15 min include Isoflurane-CF3CHClOCF2H (1) (97% [18F]fluorine incorporation, 99% radiochemical purity, respectively), Sevoflurane-CF3CHCF3OCFH2 (2) [98%, 99%], CF3CHBrOCF2H (3) [85%, 80%], Desflurane-CF3CHFOCF2H (4) [50%, 99%], Fluroxene-CF3CH2OCH = CH2 (5) [25%, 99%], Fluothyl-CF3CH2OCH2CF3 (6) [60%, 10% at a temperature of 175 degrees C], Halothane-CF3CHBrCl (7) [98%, 95%], CF3CH2I (8) [99%, 98%], CF3CH2Br (9) [18%, 98%], CF3CHCl2 (10) [95%, 98%], CF3CH2Cl (11) [90%, 20%], CF3CHClCF3 (12) [95%, 99%], (CF3)3CH (13) [99%, 99%] and HF-134a-CF3CFH2 (14) (15%, 93% at a temperature of 175 degrees C).

Anesthetics, Inhalation↗
PubMed2004

Development of fluorinated low temperature glassy carbon films for solid-phase microextraction.

Solid-phase microextraction (SPME) fibers with supported fluorinated glassy carbon are demonstrated for the first time. Oligo[1,3-dibutadiynylene-1,3-(tetrafluoro)phenylene] was synthesized and heated to temperatures that varied from 200 to 1000 degrees C to produce the fluorinated glassy carbon. The extent of graphitization of the glassy carbon increased as the processing temperature increased. The fluorinated glassy carbon selectively extracted monohalogenated benzenes from an aqueous solution when compared to the extraction of toluene. The selectivity increased in the order of phi-F < phi-Cl < phi-Br < phi-I. The selectivity for the halogenated compounds was greatest for the fluorinated glassy carbon phase processed at temperature below approximately 400 degrees C. Preliminary studies on the retention mechanism of the LTGC phase show that dispersive interactions are very important to the retention of halocarbons on the fluorinated LTGC. Finally, the selectivity of the fluorinated LTGC for halogenated compounds was compared to that of commercially available SPME fibers, such as poly(dimethylsiloxane), poly(dimethylsiloxane)/divinylbenzene (PDMS/DVB), and poly(dimethylsiloxane)/Carboxen (PDMS/Carboxen) fibers. As expected the fluorinated LTGC was more selectivity for the halogenated compounds. Interestingly the order of the increase in selectivity is opposite when comparing the fluorinated-LTGC and the three commercial fibers. A decrease in selectivity was observed going from fluorobenzene to iodobenzene using PDMS/DVB and PDMS/Carboxen fibers. While for the pure PDMS phase, there is a slight increase in selectivity from fluorobenzene to chlorobenzene but the remaining trend shows little change for bromobenzene and iodobenzene.

Carbon↗
PubMed2004

Synthesis, antimicrobial activity and molecular modeling studies of halogenated 4-[1H-imidazol-1-yl(phenyl)methyl]-1,5-diphenyl-1H-pyrazoles.

During the course of our studies in the azole antifungals area, we synthesized a number of 1,5-disubstituted 4-[1H-imidazol-1-yl(phenyl)methyl]-1H-pyrazoles, analogues of bifonazole. 1,5-Diphenyl-1H-pyrazole 3 showed weak antimycotic and antibacterial activities in vitro against Candida albicans, Cryptococcus neoformans and Staphylococcus aureus. In order to increase these properties, given that the halo substitution was found to be capable of enhancing antifungal effects, we prepared a series of fluoro and chloro derivatives of 3. The microbiological evaluation carried out on newly synthesized compounds included in vitro assays for antifungal, antibacterial and antimycobacterial activities. Among the tested compounds, some dichloro and trichloro-derivatives showed interesting antimicrobial properties. In particular, compounds 10j,k,l produced inhibitory effects against pathogen representatives of yeast (C. albicans, C. neoformans) and Gram positive bacteria (S. aureus) similar or superior to those of bifonazole. In addition, their activity against Mycobacterium tuberculosis was superior to that of clotrimazole and econazole, which were used as reference drugs. The replacement, in these compounds, of chlorine with fluorine atoms led to inactive derivatives. Docking studies were carried out on the most active compounds, in order to rationalize the pharmacological results.

Anti-Bacterial Agents↗
PubMed2001

Quantitative determination of vapor-phase compound A in sevoflurane anesthesia using gas chromatography-mass spectrometry.

BACKGROUND: During low-flow or closed-circuit anesthesia with the fluorinated inhalation anesthetic sevoflurane, compound A, an olefinic degradation product with known nephrotoxicity in rats, is generated on contact with alkaline CO(2) adsorbents. To evaluate compound A formation and thus potential sevoflurane toxicity, a reliable and reproducible assay for quantitative vapor-phase compound A determination was developed. METHODS: Compound A concentrations were measured by fully automated capillary gas chromatography-mass spectrometry with cryofocusing. Calibrators of compound A in the vapor phase were prepared from liquid volumetric dilutions of stock solutions of compound A and sevoflurane in ethyl acetate. 1,1,1-Trifluoro-2-iodoethane was chosen as an internal standard. The resulting quantitative method was fully validated. RESULTS: A linear response over a clinically useful concentration interval (0.3-75 microL/L) was obtained. Specificity, sensitivity, and accuracy conformed with current analytical requirements. The CVs were 4.1-10%, the limit of detection was 0.1 microL/L, and the limit of quantification was 0.3 microL/L. Analytical recoveries were 100.6% +/- 10.1%, 102.5% +/- 7.3%, and 99.0% +/- 4.1% at 0.5, 10, and 75 microL/L, respectively. The method described was used to determine compound A concentrations during simulated closed-circuit conditions. Some of the resulting data are included, illustrating the practical applicability of the proposed analytical approach. CONCLUSIONS: A simple, fully automated, and reliable quantitative analytical method for determination of compound A in air was developed. A solution was established for sampling, calibration, and chromatographic separation of volatiles in an area complicated by limited availability of sample volume and low concentrations of the analyte.

Air↗
PubMed2000

The first alpha-fluoroallenylphosphonate, the synthesis of conjugated fluoroenynes, and the stereoselective synthesis of vinylfluorophosphonates using a new multifunctional fluorine-containing building block

Limitations on current methodologies for the introduction of CF(2) and CFH in complex alpha-fluorophosphonates led to the synthesis of a fluorine-containing building block TIPS-C&tbd1;CCFXP(O)(OEt)(2), where X = H or F. This multifunctional fluorine synthon reacts with carbonyl compounds under WHE conditions to give high yields of fluorinated conjugated enynes and enediyne. When X = F, trapping of the desilylated anion with an electrophile after TIPS removal provided exclusive access to gamma-substituted derivatives of alpha-fluorophosphonates. When X = H, TBAF deprotection of the silyl group yields H(2)C=C=CFP(O)(OEt)(2) through an allenyl-propargyl resonance stabilized anion. The allene moiety has been used as template in the stereoselective synthesis of alpha-fluoro-beta, gamma-diiodopropenyl phosphonate, via electrophilic iodination, and alpha-fluoro-gamma-amino-alpha,beta-unsaturated phosphonates, including unsaturated phosphononucleosides, by nucleophilic displacement of an allylic iodide. Hydroamination of H(2)C=C=CFP(O)(OEt)(2) using secondary amines produced (Z)-alpha-fluoroenaminophosphonates, whereas Diels-Alder cycloaddition with cyclopentadiene provides the corresponding exocyclic vinylfluorophosphonate.

Journal Article↗
PubMed1994

Differential effect of medium potent nonhalogenated double-ester-type and conventional glucocorticoids on proliferation and chemotaxis of fibroblasts in vitro.

Recently several attempts have been made to develop glucocorticoids which show less pronounced side effects. We intended, therefore, to use experimental systems to examine the influence of newly developed nonhalogenated glucocorticoids and conventional fluorinated congeners, demonstrating similar anti-inflammatory activity in vivo, on biosynthetic capacities of human fibroblasts. Fibroblasts were kept in monolayer cultures and exposed to different concentrations of the active compounds for 6 days to analyze the influence on proliferation. Chemotaxis of fibroblasts was studied in blind well Boyden chambers. Fibroblast-conditioned medium was used as chemoattractant. All glucocorticoids tested influenced fibroblast proliferation at high (10(-5) M) and low (10(-9) M) concentration. Yet the effect was clearly more marked with fluorinated compounds. Basically, the same applied for chemotaxis. At the low concentration, however, nonfluorinated glucocorticoids exerted almost no influence. These results suggest that modifications of steroidal structure can specifically influence their effects on biosynthetic capacities of fibroblasts.

Adult↗
PubMed2003

Improved synthesis of pure [18F]fluoro-compounds for PET studies from bromo-compounds.

For preparing [18F]labeled compounds free from bromo-compounds for PET (positron emission tomography) studies, we propose the following two processes in which no separation is needed between the fluoro-compound and bromo-compound : (1). the bromo-compound is first converted into O-tosylate, which is then [18F]fluorinated; and (2). after [18F]fluorination of the bromo-compound, its excess is converted into an easily separable compound, e.g., phthalimide-compound. Direct tosylation with silver tosylate was effected in 65-85% yield for most commercial bromo-compounds, and with potassium phthalimide, the bromo-compounds in cold run were converted easily into phthalimide-compounds in 84-90% yield.

Chemistry, Organic↗
PubMed1989

New class of 19F pH indicators: fluoroanilines.

The pH dependence of the 19F chemical shift has been characterized for a number of fluorine-substituted aniline derivatives. These compounds constitute a new class of 19F nuclear magnetic resonance (NMR) pH indicators, characterized by single 19F resonance lines with sensitivities ranging from 2 to 7 ppm/pH unit near the aniline pKa; total shifts between conjugate acid and base of 5-15 ppm; and pKas ranging from 1 to 7. One compound, N,N-(methyl-2-carboxyisopropyl)-4-fluoroaniline, has a pKa of 6.8 and a sensitivity of 5 ppm/pH unit. This compound displays significant broadening of its 19F resonance near the aniline pKa (6.8), due to a decreased rate of exchange between conjugate acid and base species. Our results are consistent with slow dissociation of an intramolecular hydrogen bond in the zwitterionic species that limits the exchange rate between protonated and unprotonated forms for N,N-(methyl-2-carboxyisopropyl)-4-fluoroaniline.

Aniline Compounds↗
PubMed1997

Time course of alpha-fluorinated valproic acid in mouse brain and serum and its effect on synaptosomal gamma-aminobutyric acid levels in comparison to valproic acid.

To prevent the hepatotoxicity of valproic acid (VPA), a fluorine substituent was introduced at the alpha-position to eliminate the formation of putative toxic metabolites through mitochondrial beta-oxidation. Although the alpha-fluorinated VPA analogue (alpha-fluoro VPA) is more acidic (pK(a) = 3.55) than VPA (pK(a) = 4.80), the lipophilicity of these two compounds, as determined by their log P values, were similar when compared at pH 2.5. Brain, serum and urine samples were prepared from mature male CD-1 mice treated with either alpha-fluoro VPA or VPA for quantitation of drug concentrations. Brain synaptosomes were isolated to determine gamma-aminobutyric acid levels. After equivalent doses of 0.83 mmol/kg, alpha-fluoro VPA was characterized by its slower access into mouse brain, compared to VPA. The peak concentration of alpha-fluoro VPA in mouse brain was achieved 45 min later than in the serum, whereas the peak brain level of VPA coincided with the peak serum level occurring within 15 min. Simultaneous curve fitting of both brain and serum drug concentrations using a two-compartment model indicated that alpha-fluoro VPA, like VPA, may be asymmetrically transported across the blood-brain-barrier. This property of alpha-fluoro VPA was also reflected in its low brain-to-serum concentration ratio of 0.09 at the peak brain drug concentration (0.16 for VPA). The primary beta-oxidation metabolite of VPA was not found in the serum and urine of mice treated with alpha-fluoro VPA. Although the glucuronide was a major metabolite of VPA (28.5% of the dose), alpha-fluoro VPA was observed to conjugate extensively with L-glutamine (33.3% of the dose). Alpha-fluoro VPA appeared to persist in the general circulation, which, in turn, may contribute to the apparent slow elimination of the drug from the brain. The fluorinated compound was demonstrated to have anticonvulsant activity in the 1,5-pentamethylenetetrazole seizure test and to be capable of increasing brain synaptic gamma-aminobutyric acid, the ED50 being 1.70 mmol/kg. These results suggest that alpha-fluoro VPA has potential as a new anticonvulsant drug.

Animals↗
PubMed2006

Significant residual fluorinated alcohols present in various fluorinated materials.

Polyfluorinated telomer alcohols and sulfonamides are classes of compounds recently identified as precursor molecules to the perfluorinated acids detected in the environment. Despite the detection and quantification of these volatile compounds in the atmosphere, their sources remain unknown. Both classes of compounds are used in the synthesis of various fluorosurfactants and incorporated in polymeric materials used extensively in the carpet, textile, and paper industries. This study has identified the presence of residual unbound fluoro telomer alcohols (FTOHs) in varying chain lengths (C6-C14) in several commercially available and industrially applied polymeric and surfactant materials. NMeFOSE, a perfluoroalkyl sulfonamido alcohol, was also detected in a commercially available carpet protector product. A method was developed to remove these residual compounds from polymeric and surfactant materials by dispersion in water and stripping of the volatiles using a constant flow of air and trapping on XAD resin. Using gas chromatography mass spectrometry analysis, it was determined that the fluorinated materials examined consist of 0.04-3.8% residual alcohols on a fluoro alcohol to dry mass basis. These values indicate that residual alcohols, left unreacted and unbound from the manufacturing process of fluorinated polymers and surfactants, could be a significant source of the polyfluorinated telomer alcohols and sulfonamides released into the environment. This study suggests that elimination or reduction of these residual alcohols from all marketed fluorinated polymers and fluorosurfactants is key in reducing the prevalence of perfluorinated acids formed in the environment.

Fluorine Compounds↗