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Semipermeable hydrogels formed with a biocompatible alginate solution and Ba(2+) ions protect encapsulated cells and tissues from a foreign immune system. For the viability and metabolic activity of the encapsulated materials, a sufficient oxygen supply inside the capsules is necessary. Quantitative (19)F-MRI was performed on perfluorocarbon-loaded alginate capsules implanted into the peritoneal cavity, the musculus quadriceps femoris, and beneath the kidney capsule of rats, in order to determine in vivo the partial oxygen pressure (pO(2)) inside the capsules at these implantation sites. The temporal behavior of the pO(2) values was observed for at least 3 months. The most stable values over time were observed in the kidney, where inter-rat pO(2) differences were considerable. In the muscle, the values were very high directly after implantation and decreased to nearly zero after 2 weeks. In the peritoneal cavity, values changed randomly over a wide range between different rats and over time. Magn Reson Med 42:1039-1047, 1999., (Copyright 1999 Wiley-Liss, Inc.)

Background: Investigation of the effects of different perfluorochemicals (PFC) on cultured dorsal root ganglion (DRG) cells., Method: DRG cell cultures from 9- to 11-day-old chicken embryos were exposed to emulsified perfluorodecalin (PFD; C10F18; 0.5%, 1% and 10%) or perfluorooctylbromide (PFO; C8F17Br; 0.5%, 1% and 10%). The cells were evaluated under phase-contrast optics after 30 h and 120 h for 0.5 and 1% and after 5 h for 10%. To study the integrity of neuronal cells, immunohistochemical labelling for neurofilaments (NF) and tubulin (TUB) was performed., Results: Concentrations of 0.5% and 1% of PFD or PFO did not change immunohistochemical labelling of DRG cells. Co-cultured macrophages showed a foam cell response, presumably representing ingested PFC. At both concentrations PFD induced a weaker foam cell response than PFO. A concentration of 10% led to the death of DRG cells and macrophages within 5 h., Conclusion: PFC caused a dose-dependent damage of neuronal cells. Co-cultured macrophages developed a foam cell response similar to that observed in vivo after prolonged presence of PFC in the vitreous body. These observations indicate that PFD and PFO may not be suitable for long-term vitreous replacement in vitreoretinal surgery. However, the model is limited by several factors: (1) there are physiological differences between DRG cells and retinal ganglion cells; (2) in vivo retinal ganglion cells are protected by the overlying tissues; (3) the PFC used in tissue culture must be emulsified.

The aim of this study was to investigate the extent to which ischemia and reperfusion lead to oxidative damage of the retinal tissue and investigate how ischemic and reperfused retinal tissues react to the application of perfluorooctylbromide (PFOB) and, if this reaction can be influenced by protective drugs such as vitamin E (Vit.E). The experiments were performed with 60 male Wistar rats, divided into 12 groups using an established model of reversible ischemia and reperfusion of the globe. Grouping of animals was carried out according to different ischemia and reperfusion periods and different therapeutic regimens (PFOB, Vit.E). Treatment with PFOB and/or Vit.E was performed after 60 min of ischemia with 60 min of reperfusion. At the end of the experiments thiobarbituric acid reactive substances (TBARS) were determined in the retinal tissues and served as parameters of oxidative tissue damage. Ischemia of up to 60 min led to a significant increase in TBARS values. Ninety and 120 min of ischemia led to no further significant elevation compared to the 60 min or 90 min group. Following 60 min of ischemia, a reperfusion period of 15 min led to an increase in TBARS values that was significant (P<0.05) after 30 and 60 min. Addition of PFOB resulted in a further significant (P<0.05) increase in TBARS values as compared to the respective group without treatment. Vit. E alone did not change the values significantly compared to the respective group without treatment. However, the application of Vit.E in addition to PFOB led to a significant reduction in TBARS values. Ischemia resulted in severe oxidative retinal tissue damage, which increased during reperfusion. The reperfusion damage might be due to the known depletion of protecting substances such as vitamin E. Enhancement of oxygen supply by PFOB during reperfusion without any tissue protection leads to more severe damage. Thus, additional protection of the tissue by powerful antioxidants is necessary when providing oxygen for better tissue recovery., (Copyright 1998 Academic Press Limited.)

Four perfluorochemicals, Bis-[F-butyl]ethene, perfluorocyclohexylmorpholine, perfluorodecalin and perfluorooctylbromide were compared by their influence on the liver cytochrome P-450 system, measuring the pentobarbital sleeping time as defined by the time of loss of the righting reflex in rats. In all experiments first a prolongation of barbital detoxification was observed, which lasted at least 2-4 days. Thereafter a very long extended period of abbreviated sleeping time followed which was only missed after perfluoroctylbromide. Thus substrate competition, uncoupling of monooxygenation and enzyme induction determine the detoxifying processes in the liver that follow the administration of perfluorochemicals.

Purpose: An intravitreal injection of Fluosol-DA leads to a higher alteration of the macrophage system of the retina than perfluorooctane and perfluorodecalin administered by the same route. The difference may be due to different kinds of oxidative damage caused by the three chemicals. To test the validity of this assumption, the degree of cell alteration, expressed as reduction of cytoplasmic motility, caused by these three perfluorochemicals was examined., Methods: Using the hepatic macrophage system of the rat, cell alteration was examined by magnetometry after intravenous application of various perfluorochemicals [emulsified perfluorodecalin (C10F18), perfluorooctane (C8F17Br) and Fluosol-DA (corresponding to a 20% emulsion of 70% perfluorodecalin and 30% perfluorotripropylamine, C9F21N)]., Results: After administration of high doses, all perfluorochemicals led to cytoskeleton alteration. This alteration, expressed as retardation of the relaxation period of ferromagnetic iron oxide particles, was most pronounced after administration of Fluosol-DA., Conclusion: The compromising effect of perfluorochemicals is dose dependent and differs among the three compounds tested, with Fluosol-DA showing the greatest decrease in cytoplasmic motility.

Purpose: To clarify whether the prolonged presence of perfluorochemicals (PFC) in the vitreous cavity causes oxidative tissue damage and inflammatory response of the retina and, if so, what the process is., Methods: After three different perfluorochemicals [perfluorodecalin (C10F18), perfluorooctane (C8F18) and Fluosol-DA (corresponding to a 20% emulsion of 70% PFD and 30% perfluorotripropylamine, C9F21N)] had been in the vitreous cavity of rabbits for 2 weeks, lipid peroxide concentration and myeloperoxidase activity in the retina were determined., Results: Whereas only Fluosol-DA showed significant oxidative damage, the inflammatory activity was significantly increased in all groups., Conclusion: The increased myeloperoxidase activity and the observed oxidative damage of the retina seem to be the effect of both perfluorochemical-loaded macrophages and inflammatory-induced lipid peroxidation.

An overview is presented on methods used to judge the effect of different perfluorochemicals (PFCs) on functional organ changes. By some of these methods the function of the reticuloendothelial system (RES) after a load with PFC was tested, either globally in form of the clearance of colloidal carbon particles or by a magnetometric method to test the phagocytosing function of macrophages within the liver of rats. An endotoxin test on survival of mice after the combined treatment with lipopolysaccharides of E. coli and PFCs showed the importance of a cumulative effect of multiple factors influencing phagocytosis. Other methods examined the influence of PFCs on lipid peroxidation during reperfusion of the ischemic intestine or on the effects of hyperbaric oxygen on the lung. The half-life (mean dwell time) of PFCs within organs with a high storage rate could optimally be determined by means of 19F magnetic resonance imaging in longitudinal studies within the same animal. An influence of PFCs on hepatocytes was tested by determining the time required for detoxifying pentobarbital as measured by the sleeping time (until reappearance of the righting reflex). By all these tests a strong dose-dependence was found, so that effects observed with a high load may become negligible with smaller dosages.

The activity of liver macrophages was evaluated using a magnetometric method after administration of different perfluorochemicals. Following treatment with perfluoroctylbromide a significant shorter time period of diminished macrophage activity was found compared with a mixture of perfluorodecalin and perfluorotripropylamine. Results obtained with the magnetometric method on liver macrophages were more sensitive compared with those of colloidal carbon clearance of total body RES.

By means of colloidal carbon clearance loading of cells of the reticulo-endothelial system (RES) in rats was estimated after administration of perfluorochemicals. Perfluorocylbromid revealed a significant lower depression of RES function than an equally dosed (g/kg b.wt.) mixture of perfluorodecalin and perfluorotripropylamine. Compared with a magnetometrical measurement of liver macrophage activity, shorter periods of cell loading was determined.

The influence of a temporary occlusion of the superior mesentery artery on the generation of oxygen free radical products was tested in controls and after administration of perflubron. The occlusion time lasted for 90 min and a reperfusion time of 150 min was chosen until examination of tissue samples took place. The content of thiobarbituric acid reactive substances (TBARS), glutathione (GSH) and myeloperoxidase (MPO) was determined in homogenized tissue samples. A protective effect of antioxidants or radical scavengers was tested in form of alpha-tocopherol and allopurinol. A highly significant increase of TBARS was found in the operated control group, still higher under perflubron (perfluoroocytylbromide, PFOB). However, under alpha-tocopherol as well as under allopurinol the effect of radical products could be diminished below the values of controls. GSH and MPO were not significantly changed under PFOB as compared to the operated control group.

The effect of a stable perfluorodecalin (FDC) emulsion, based on addition of 0.2-0.5% (W/V) of perfluoroperhydrophenanthrene and 4% egg yolk lecithin was tested for its influence on Kupffer cells in vivo by means of a magnetometric procedure in rats. It was also compared with the effect of a perfluoro-chemical emulsion (PFC) of the first generation (FluosolR-DA, FDA). While doses of 0.1 g/kg body weight of both PFCs caused a small increase of activity in these cells (as measured by an increase in a ratio factor r after magnetization), doses of 1 g/kg b.wt. led to a significant retardation of intracellular movements after FDC and FDA for two and four days, respectively. A dose of 3 g/kg b.wt. of FDC effected a significant depression for 8 days, whereas after the same dose of Fluosol-DA the intracellular motility remained depressed for as long as 32 days.

Exposure to hyperoxia, especially under hyperbaric conditions, causes an enhanced oxidative stress particularly in lung tissue. To test the potential hazardous effect of either a single or repeated hyperbaric oxygen treatment (HBO) on the cellular defence system the glutathione status of lung tissue from rats exposed to HBO was investigated. When daily exposed to 2.5 ATA of > 95% O2 for 90 min over 8 or 14 days the content of reduced glutathione in lung tissue (GSH) increased by 16-19%. Oxidized glutathione (GSSG) tended to increase after 8 days and was 56% higher after 14 days. While the GSSG/GSH ratio was unchanged after 8 days, it increased by 39% after 14 days. Thus, the GSH increase after 8 days can be understood as a adaptive process to protect the lung from oxidative stress. The distinct increment of the cellular GSSG that lead to an increase of the GSSG/GSH ratio after 14 days reflects a situation, in which the cellular defence system is overwhelmed by oxidative stress. The additional pretreatment with perfluorochemicals in a dose of 2g/kg every second day aggravated the observed changes (GSH +39-19%, GSSG +118%). In a second experiment rats were exposed to a single session with 7 ATA of O2 for 60 min. GSH in the lungs increased for 40%, it was not elevated by PFC. However, GSSG increased to a much higher degree in untreated as well as in PFC-treated animals (+240%, +163%), elevating the ratio GSSG/GSH markedly (+145%, +176%). Allopurinol given as radical scavenger in a dose of 50 mg/kg was able to suppress the increased oxidative stress widely. Thus adaptive and overloading processes are involved under the treatment with increased oxygen pressures. As the administration of PFC aggravates the observed changes, a still increased blood oxygen offer must be considered as the causative agent. A radical scavenger is capable to suppress the increased oxidative stress widely.

P-cyclohexylmorpholine, given as oxygen carrier of second generation, was tested in two experimental models: the ischemic intestine and the lung under hyperbaric oxygen condition. In both instances in separated groups either alpha-tocopherol or allopurinol was additionally given as oxygen free radical scavenger. The thiobarbituric acid reaction (TBAR) was used as screening test for the occurrence of lipid peroxidation in organ probes; further the content of glutathione in reduced (GSH) and oxidized form (GSSG) was determined. Whereas only slight increases of TBAR substances and GSSG could be found compared to controls, the effect of the administrated scavenging drugs was very impressive: they could suppress nearly totally the effect of an enhanced oxidative stress.

The sleeping time after administration of pentobarbital at 30 mg/kg body weight (BW) was used in rats as a simple, noninvasive screening test of liver function. In controls, repeated tests showed no shortening of the time and thus no signs of enzyme induction. After the injection of perfluorochemicals in the form of Fluosol-DA at doses of 4.4 and 10 g/kg BW, significant prolongations occurred that, in case of the higher dose, lasted only until the fourth day. The formerly observed liver cell proliferation thus seems to have a compensating effect, since the detoxifying function was restored when the maximum of increased liver mass was reached.

The decline of the concentration of perfluorochemicals (PFC) after a single injection of three different doses was studied in the circulation of rats. The doses used amounted to 4.4, 10 and 14 g/kg body weight of Fluosol-DA, an emulsion of 7 parts of perfluorodecalin (FDC) and 3 parts of perfluorotripropylamine (FTPA). This also allowed testing of the composition of the emulsion remaining in the circulation and of that found in the liver. After two days a decrease of the half life from 34.0 +/- 0.7 to 17.1 +/- 4.3 h was found within the circulation at the highest dose. At the same time a change in the composition of the emulsion in the blood stream occurred, favouring the fraction of FTPA. FTPA increased from 28.3 +/- 1.4 to 54.4 +/- 8.1% on the fourth day. Whereas in the cells of the liver PFC droplets may be broken up, freed from their surfactant layer and handled according to their individual components, for PFC in the blood stream an unchanged composition should be assumed. Both results, the decreasing half life and the change in composition of the circulating emulsion may best be explained by a shrinking and instability of the emulgator film, showing the necessity for development of a superior surfactant.

Perfluorodecalin and perfluorotripropylamine which have N2 solubility coefficients of 28.4 and 35.7 ml/dl, respectively, were used for treatment of decompression sickness in this study. Rats with chronically implanted venous catheters were held for 30 min at 800 kPa (7 bar, 8 ATA) by introducing compressed air into a chamber in which they were kept; a relatively short period of decompression followed (200 kPa/min). Immediately thereafter injections of the perfluorochemicals (PFCs) in a dose of 10 g/kg were given, controls received saline in the same volume or remained without treatment. An observation period of 2 h followed; after this time the incidence of death amongst the experimental animals (as compared with controls tested by the chi 2-test) showed that PFC treatment increased the likelihood of survival. Probit-log time relationship for the incidence of death also revealed a significant decrease in lethality in treated rats 30 min after the end of decompression. The mean lethal times Lt50 differed significantly, too. A still greater effect might be expected if the PFC emulsion were deprived of its normal nitrogen content by oxygenation before administration. Under the conditions of the present experiments PFCs produced an improvement in N2 exhalation at least in terms of the survival rate after compression followed by a very short decompression time.

The effect of an emulsion of perfluorochemicals (PFC) (7 parts perfluorodecalin and 3 parts perfluorotripropylamine, 4.4 g PFC/kg body weight) on organ function was determined. Whereas maximal storage of PFC was reached in the spleen as early as 12 h after PFC administration, the liver attained a maximal PFC content only after 2 days. The increase in weight also differed: a maximum occurred in the spleen on the 4th day, in the liver on the 8th day. Indocyanine green (ICG) clearance showed a small decrease, statistically significant after 12 and 24 h. Colloidal carbon clearance, used as a measure of the function of the reticuloendothelial system (RES) decreased instantly after PFC to less than half the control value; after full recovery a second decrease was seen which lasted till the 4th day after PFC. Pretreatment with C 48/80 or with increasing doses of E. coli endotoxin could largely obviate the depressive effect of PFC-loading on carbon clearance. Serum transaminases increased to about twice the control levels but were normal by the 2nd day, and thereafter. Alkaline phosphatase showed a 2.5 fold increase but returned to control level after the 2nd day. It is concluded that while a severe disturbance of liver function did not occur, the reduction in the capacity of the RES can become a serious factor in the defence against a simultaneously appearing infection if not compensated by activating the RES.

Treatment with perfluorochemicals (PFCs) shows a temporary decrease in phagocytic activity as measured by carbon clearance. The importance of this effect was checked by investigating the lethality after administrations of PFCs and Escherichia coli endotoxin in mice (NMRI strain). When endotoxin was applied simultaneously with PFC (4.4 g/kg body weight, a dose which could compensate a loss of a third of blood volume) the lethality rose 7.8-fold. If the challenge with endotoxin occurred later than 12 h after PFC injection, the increase of lethality was of a distinctly smaller degree. By means of pretreatment with various substances the increased lethality of endotoxin could be shifted in the direction of the control. C 48/80, aristolochic acid, and hydrocortisone were effective in this respect; zymosan remained ineffective. The results show a weakened resistance towards toxins from the intestinal tract under PFC administration; precaution in this regard should be taken during therapy with PFC.

Changes in the activity of the RES were examined by: 1. the clearance of colloidal carbon in rats (expressed by the elimination constant K); 2. determination of the tolerance of endotoxin in mice and that of gram negative enterobacteria in rats (expressed in both methods by the lethality); 3. evaluation of the temporal course of weight and the amount of PFCs taken up by two chief organs of the RES--liver and spleen. The results revealed a distinct temporal action of PFCs on the function of the RES which was terminated before cellular responses ended.

After the infusion of perfluorochemicals (PFC) given as artificial blood gas carriers a temporary storage of the inert substances in tissues of the organism occurs. The time course of this effect was investigated in longitudinal studies in the rat and compared with changes of different organ functions, expressed as changes in the levels of serum enzymes, in the elimination of indocyanine green and in the duration of pentobarbital sleeping time which are dependent on the excretory and detoxifying functions of the liver. The intensity of the elimination of colloidal carbon was used as a measure of the activity of the reticulo endothelial system. Observation of the time course of these functional tests in comparison with the storage of PFC and changes in organ weight of liver and spleen showed that diminutions in function had a distinctly shorter duration than PFC storage, whereas the longest lasting effects were seen in organ weight increase is regarded as a compensatory effect that is associated without functional loss at the maximum of its appearance.

Different O values of the perfused rat liver and the metabolic turnover of urea and glucose, with and without substrate loads, were measured in a hemodiluted control group and in a group perfused with the perfluoro compound emulsion (PFC) Fluosol-DA. The following results were obtained. The basal O consumption with PFC was 6.42 and 6.51 ml O/(min·100 g liver), respectively, both being higher than in the control group, despite the fact that the latter revealed values of a good oxidative metabolism compatible with that found for larger species in situ. With substrate loads the values increased to a mean of 8.62 ml O/(min·100 g) for periods of 20 min and more. Also O extractions of 95% could be found like otherwise mostly in cases with severely reduced O supply and under diminished O consumption. This seems to be due to the increased surface area of the O transporting particles with a mean diameter of 0.1 μm. Furthermore, the linear O delivery of physically dissolved oxygen from PFC enables a higher O pressure to remain in the outflowing perfusate after the same amount of oxygen is consumed, provided sufficiently high arterial O pressures are used. Finally, an increase of intracellular O concentration rather than O tension by incorporated PFC particles might play a role.-The substrate turnover values were compared with those in the literature; they are within the normal range. [ABSTRACT FROM AUTHOR]