Letter: Fluorocarbons and the ozone shield.
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Atmosphere↗
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A second generation of artificial cornea (Biokpro II).
The properties of a new second-generation colonizable artificial cornea were evaluated in humans. The prosthesis consisted of a peripheral rim of a translucent microporous fluorocarbon polymer (expanded polytetrafluoroethylene) fused with the polymer of the central optic. The optic was made of medical-grade polydimethylsiloxane coated with polyvinylpyrrolidone. Its refractive power was 42.2 diopters and it measured 7.0 mm in diameter and 0.55 mm in thickness. The geometry of the optic was tested by high-frequency ultrasound and intraocular pressure and distensibility were measured in an artificial chamber. Prostheses were implanted in one eye of 13 humans. The average follow-up was 6 months (range 3-9 months). Most of the eyes (11/13) were clinically stable after a 7 months follow up. Seven patients had visual acuity improvements. Mean corrected final visual acuity was 20/200 (range, 20/30 to light perception). Five anatomical failures occured (two extrusions, two retroprosthetic membranes, one endophthalmitis). The new optical core, junction, and surface properties of the polymers offer many advantages, quicker colonization of the supporting skirt, and an optical core with a geometry similar to that of a normal human cornea. Epithelial cells did not migrate over the interface and optical core. It seems that formation of an epithelium over the artificial device is essential for the long-term stability of the implant.
Adult↗
Endothelial damage caused by uncoated and fluorocarbon-coated poly(methyl methacrylate) intraocular lenses.
PURPOSE: To assess endothelial damage induced by poly(methyl methacrylate) (PMMA) intraocular lenses (IOLs) coated with a fluorocarbon polymer, Teflon AF, to make them highly hydrophobic. SETTING: Department of Ophthalmology. Hôtel-Dieu Hospital, Paris, France. METHODS: Ten Teflon-coated and 10 uncoated PMMA IOLs were used in an in vitro static touch model. The corneal endothelium was placed in direct contact with the IOL for 15 seconds and then stained with trypan blue and alizarin red. The endothelial damage produced by each IOL in the area of contact was assessed semiquantitatively and quantitatively. RESULTS: Teflon-coated IOLs produced significantly less endothelial damage than uncoated PMMA IOLs (P < .0001). Endothelial cells in contact with Teflon-coated IOLs did not usually adhere to the IOL surface. In contrast, the uncoated IOLs produced large areas of endothelial cell loss. CONCLUSION: Teflon-coated PMMA IOLs have an antiadhesive effect that reduced endothelial damage after IOL insertion in an in vitro model.
Animals↗
Cardias arrhythmias in hypoxic rabbits during aerosol propellant inhalation.
Rabbits were exposed for four minutes to combinations of oxygen (21%, 11%, or 7%) and fluorocarbon-11 (0%, 5%, or 15%). Exposure to 7% oxygen-15% fluorocarbon-11 caused cardiac arrhythmias in all rabbits exposed. These bradyarrhythmias developed at levels of arterial hypoxemia that did not cause arrhythmias in rabbits exposed to 7% oxygen alone. In contrast with recent reports, hypoxia and this aerosol propellant do appear to have an interactive effect on cardiac rhythm.
Aerosol Propellants↗
Perfluorochemicals: potential sources of and migration from food packaging.
Perfluorochemicals are widely used in the manufacturing and processing of a vast array of consumer goods, including electrical wiring, clothing, household and automotive products. Furthermore, relatively small quantities of perfluorochemicals are also used in the manufacturing of food-contact substances that represent potential sources of oral exposure to these chemicals. The most recognizable products to consumers are the uses of perfluorochemicals in non-stick coatings (polytetrafluoroethylene (PTFE)) for cookware and also their use in paper coatings for oil and moisture resistance. Recent epidemiology studies have demonstrated the presence of two particular perfluorochemicals, perfluorooctane sulfonate (PFOS) and perfluorooctanoic acid (PFOA) in human serum at very low part per billion levels. These perfluorochemicals are biopersistent and are the subject of numerous studies investigating the many possible sources of human exposure. Among the various uses of these two chemicals, PFOS is a residual impurity in some paper coatings used for food contact and PFOA is a processing aid in the manufacture of PTFE used for many purposes including non-stick cookware. Little information is available on the types of perfluorochemicals that have the potential to migrate from perfluoro coatings into food. One obstacle to studying migration is the difficulty in measuring perfluorochemicals by routine conventional analytical techniques such as GC/MS or LC-UV. Many perfluorochemicals used in food-contact substances are not detectable by these conventional methods. As liquid chromatography-mass spectrometry (LC/MS) develops into a routine analytical technique, potential migrants from perfluoro coatings can be more easily characterized. In this paper, data will be presented on the types of perfluoro chemicals that are used in food packaging and cookware. Additionally, research will be presented on the migration or potential for migration of these chemicals into foods or food simulating liquids. Results from migration tests show mg kg(-1) amounts of perfluoro paper additives/coatings transfer to food oil. Analysis of PTFE cookware shows residual amounts of PFOA in the low microg kg(-1) range. PFOA is present in microwave popcorn bag paper at amounts as high as 300 microg kg(-1).
Caprylates↗
Penetration of soil dust through woven and nonwoven fabrics.
Several types of fabrics were laboratory-tested for their effectiveness in workers protection to pesticide-laden dust encountered in the agricultural environment. Of the applied less than 100 mesh dust, penetrations through knitted jersey and woven fabrics were greater than 87% and less than 5.8%, respectively. Treatment of woven fabrics with fluorocarbon polymers curtailed penetration by greater than 60%. Nonwoven fabrics allowed less than 0.5% dust penetration. Parathion mixed with 100-mesh sieved dust resulted in increasing "ppm" levels with decreasing particle size; extent of parathion conversion to paraoxon was independent of particle size for the sandy loam dust used.
Agricultural Workers' Diseases↗
Evaluation of a thin-film peripheral nerve cuff electrode.
This is a study of the reaction of large nerves to implantation using a flexible, thin-film cuff electrode. Cuff electrodes were implanted on the sciatic nerve of three cats. An implantation period of six weeks allowed sufficient time for any injury responses in the nerve and connective tissue sheath around the cuff to develop. The electrode came off the nerve in one of the cats. In the remaining two cats, gross observation following explantation of the electrodes revealed encapsulation of the cuffs without swelling of nerve tissue. Histological evaluation did not demonstrate nerve injury. The nerve cuff electrodes, which are comprised of titanium and iridium coatings on a fluorocarbon polymer substrate, appeared unaffected by the implantation, and connective tissue encapsulation did not adhere to either the polymer substrate or metallization. Evaluation of the electrodes using activated iridium oxide charge injection sites in more extended studies is now being undertaken.
Animals↗
Effects of varying aeration treatment on fertilizing capacity of semen diluted with perfluorochemical emulsion and stored for twenty-four hours.
The effects of perfluorochemical (PFC) oxygen carriers in turkey semen diluents on fertility and hatchability was measured for a 10-wk period. Semen was diluted (1:1) with Beltsville Poultry Semen Extender (BPSE) or BPSE:FC-75, an emulsified mixture of BPSE and perfluorobutyltetrahydrofuran (technical grade) (FC-75) and stored for 24 h at 5 C with agitation (150 rpm) and aeration with either air, nitrogen (100%), or oxygen (100%). Sperm concentration and percentage of dead sperm were determined prior to and after storage. Sperm concentration (8.35 to 9.21 x 10(9) per milliliter) was not significantly affected by the type of diluent or aeration gas, and only stored semen diluted with BPSE: FC-75 and aerated with nitrogen had increased percentage of dead sperm. Diluent type did not affect the percentage of fertilized eggs; however, fertility and hatchability for both diluent treatments with nitrogen aeration was significantly lower (P < or = 0.05) than for the semen treatments with air or oxygen aeration. Hatchability for semen diluted with BPSE:FC-75 and aerated with oxygen (63.7%) was significantly higher (P < or = 0.05) than that for BPSE-diluted semen aerated with oxygen (43.2%). Although use of oxygen carrying fluorocarbon emulsified with BPSE did not further improve fertility when the semen was stored for 24 h while oxygenated and mechanically agitated, a beneficial effect was noted for hatchability. The fact that nitrogen severely depressed fertility confirms that the beneficial effects of agitation are due to oxygenation of the spermatozoa. Therefore, further studies of oxygen carriers in semen are warranted.
Air↗
Death due to fluorocarbon inhalation.
The abuse of inhalation of aerosol preparations containing fluorocarbons as the propellant is a potentially lethal act. I report a death believed due to inhalation of an aerosol propellant.
Adolescent↗
Short term performance evaluation of a perfluorocopolymer coated gas exchanger for arteriovenous CO2 removal.
A new perfluorocopolymer coating for micropore hollow fiber gas exchangers was developed to improve gas exchange, reduce plasma leakage, and reduce blood-surface interactions. The present authors evaluated gas exchanger performance using this new coating in a prospective, randomized, controlled, unblinded, large animal model of CO2 retention. Adult sheep (30-40 kg), under general anesthesia, underwent cannulation of the carotid artery (12 F) and jugular vein (14 F). The perfluorocopolymer coated (n = 5) and uncoated (n = 5) gas exchangers were attached to an arteriovenous CO2 removal (AVCO2R) circuit. Blood gases, CO2 removal, and hemodynamics were monitored throughout the 6 hour study. Average CO2 removal was 107.6 +/- 15.6 ml/min (coated) vs. 93.0 +/- 13.9 ml/min (uncoated; p < 0.01). PaCO2 and CO2 removal for both coated and uncoated did not deteriorate significantly over the study. Average AVCO2R blood flow was 1,130 +/- 25 ml/min (coated) versus 1,101 +/- 79 ml/min (uncoated; p = not significant). Likewise, cardiac output and AVCO2R blood flow did not change over the duration of the study. No significant differences in the pressure gradient or resistance between devices (coated, 6.89 +/- 1.14 mm Hg/L/min; uncoated, 6.42 +/- 0.23 mm Hg/L/min) was noted. The authors concluded that the new perfluorocopolymer coated gas exchanger improved CO2 removal without compromising hemodynamics in an acute performance evaluation.
Animals↗
Improvements in the technique of vascular perfusion-fixation employing a fluorocarbon-containing perfusate and a peristaltic pump controlled by pressure feedback.
A new improved technique for whole-body perfusion-fixation of rats and other small animals is described. The driving force is a peristaltic pump which is feedback regulated by a pressure transducer that monitors the blood-perfusion pressure in the left ventricle of the heart. The primary perfusate-fixative is composed of a blood substitute--13.3% oxygenated fluorocarbon FC-75--in 0.05 M cacodylate buffer (pH 7.4) with a 2% glutaraldehyde. The secondary perfusate-fixative is composed of 2% glutaraldehyde in 0.05 M cacodylate buffer (pH 7.4) with 20 mM CaCl2. A double-barrelled, self-holding cannula is used to cannulate the heart; the outer and inner barrels of the cannula are connected to the peristaltic pump and to the pressure transducer, respectively. The tissue oxygen tension in the rat is monitored by a subcutaneous oxygen electrode. Measurements showed that tissue hypoxia/anoxia did not develop before or during the perfusion-fixation. Thus, the technique permits study of specimens which do not exhibit fixation gradients and do not contain cells fixed in a state of asphyxia. This is substantiated by electron micrographs of cells from different organs, revealing new fine structural elements. By adding oxygenated fluorocarbon to glutaraldehyde perfusate-fixatives, enough oxygen is made accessible for cellular respiration as well as for the oxygen-consuming chemical reactions of glutaraldehyde with the tissue. Data on anaesthesia, operative manoeuvres, mechanical components of the system, preparation of fixatives and flow of the perfusate-fixatives are furnished and discussed.
Animals↗
Chlorofluorocarbon sources of environmental contamination.
The quantities of chlorofluorocarbons (FCC's) used commercially in the United States and globally are reviewed, and estimates of environmental release from the applications are made. The results indicate that sizable quantities of the FCC's that have been produced have not yet reached the environment and that regulation of U.S. applications would partly reduce, but not end, the possible destruction of stratospheric ozone.
Environmental Pollution↗
Purification of influenza virus with Arcton 113.
Arcton 113 has proved effective in the removal of host membrane fragments which cosediment with influenza virus during differential centrifugation. The virus appeared morphologically undamaged by the procedure and retained its infectivity, neuraminidase, and hemagglutinating activity. Pyrogenicity, however, was considerably reduced.
Fluorocarbon Polymers↗
Oxygen transport of colloidal fluorocarbon suspensions in asanguineous rabbits.
In anesthetized, oxygen-breathing rabbits, the entire blood volume was exchanged with a 20% colloidal fluorocarbon fluid suspension of high gas solubility. In contrast to the control animals with acute isovolemic and hypervolemic hemodilution, the fluorocarbon suspension prevented the decrease in arterial oxygen content below a hematocrit of 13%. However, the more pronounced effect of the fluorocarbon suspension on oxygen delivery occurred at higher hematocrits and was due to its efficiency as a plasma expander, since it increased the cardiac output even above the level of the hypervolemic hemodilution group. The fluorocarbon suspension also raised arterial blood pressure and total peripheral resistance due to its increased viscosity. Thus, in mild hemodilution, the fluorocarbon suspension kept oxygen utilization in the normal range by increasing cardiac output, and in extreme hemodilution it improved oxygen utilization by also raising the arterial oxygen content and arterial blood pressure. The survival time of the isovolemic control animals was 31.6 min, it was extended to 57.8 min in the hypervolemic control animals, and the rabbits with the fluorocarbon suspension lived for 124.8 min.
Animals↗
Residual levels and biochemical changes after ventilation with perfluorinated liquid.
Twenty-three beagle dogs were ventilated with perfluorinated liquid, perfluoro-1-isopropoxy-hexane (Caroxin-F) for 1 h and were reconverted to gaseous breathing. Hematologic and biochemical changes were studied in five dogs for 1 yr and the remaining animals were followed for evidence of retained Caroxin-F for up to 3 yr. We found that the dogs could be ventilated with liquid Caroxin-F and returned to spontaneous breathing of gaseous oxygen with normal blood gas exchange within 24-72 h. Serum alkaline phosphatase, serum cholesterol, and white blood cell count increased with liquid ventilation but returned to normal in less than 1 wk. Trace amounts of Caroxin-F were detected by chromatography in all tissues studied for the entire 3-yr period. The highest levels of Caroxin-F were found in the lungs and associated lymph nodes. No histologic evidence of the presence of Caroxin-F was seen except for local accumulations of vacuolated macrophages in the lungs and associated lymph nodes. We conclude that Caroxin-F can be breathed without residual deleterious effects, even though trace amounts remained for at least 3 yr.
Alkaline Phosphatase↗
Gas embolism due to intravenous FC 80 liquid fluorocarbon.
Lethal gas embolism always occurs after FC 80 liquid fluorocarbon is injected intravenously (0.1 ml/kg body mass) in dogs breathing room air but not in dogs breathing oxygenated FC 80 liquid fluorocarbon. Gas embolism is not prevented in dogs that have been injected intravenously with FC 80 when they are exposed to 2 ATA (atmospheres absolute) 20% 02-80% N2, 9 ATA 5% O2-95% He, or 1 ATA 100%, O2. In dogs that die of FC 80-induced gas embolism, free gas in the right atrium contains approximately 0.5 g FC 80/liter, and Po2 and Pco2 in the gas are in equilibrium with their corresponding tensions in right atrial blood. These observations are consistent with the hypothesis that PFC 80 in alveolar gas does not equilibrate with PFC 80 (55 mmHg) in blood. The total gas tension in pulmonary capillary blood containing FC 80 and its vapor thus exceeds the total tension of alveolar gases (atmospheric pressure). Bubbles of O2, CO2, N2, FC 80, and water vapor form in the regions of the pulmonary capillary bed where the total tension of gases dissolved in blood exceeds the absolute blood pressure.
Animals↗
A new type of fluorocarbon liquid oxygenator.
A new oxygenator based on gas transfer across liquid-liquid interfaces (liquid oxygenator) is introduced. Perfluorinated chemicals are used as gas carriers. This liquid oxygenator differs from others in its concept basing on the dispersion of the blood droplets in an inert liquid by means of shear forces. This method allows high efficiency both with respect to saturation and to required blood flow. The results of gas transfer experiments in vitro and in vivo are satisfactory.
Animals↗
Study on the binding of trichloromonofluoromethane by bovine serum albumin using a fluorescent probe technique.
Protein binding of the aerosol propellant, trichloromonofluoromethane, was studied in bovine serum albumin (BSA) solutions using the fluorescent probe technique. The propellant displaced the probe, 8-anilino-1-naphthalenesulfonate, from its binding sites and reduced the fluorescence intensity. The binding association constants, the number of binding sites, and the competitive nature of the binding interaction were investigated. The hydrophobic nature of the binding and the implication of binding displacement interactions between the fluorocarbon and plasma-protein-bound drugs were also discussed. The fatty acid impurities present in the commercial BSA were found to have no effect on the protein binding of the propellant.
Aerosol Propellants↗