Perfluorochemical Emulsion Research Articles

人工血液(PFC乳剤)の投与による微小循環血行動態の変化

人工血液(PFC乳剤)の投与による微小循環血行動態の変化

血中Perfluorochemicals Emulsion (PFC-E)除去方法の検討

血中Perfluorochemicals Emulsion (PFC-E)除去方法の検討

Human Albumin Binding of Tamoxifen in the Presence of a Perfluorochemical Erythrocyte Substitute

The binding of tamoxifen (an HSA site IV ligand) to human serum albumin (HSA) in the presence of a perfluorochemical (PFC) erythrocyte substitute has been examined. Standard centrifugation followed by supernatant ultrafiltration was used to study the binding of 0.1 and 0.5 microgram mL-1 tamoxifen at ambient conditions. Tamoxifen was extensively bound (greater than 99%) to the PFC emulsion through an association with the emulsifiers of the droplets. Tamoxifen was also extensively bound (greater than 99%) to HSA. The percent free tamoxifen increased upon HSA dilution. Tamoxifen was extensively bound by various mixtures of HSA and the PFC emulsion and the percent free drug was similar to those obtained with HSA alone. However, the position of drug binding (PFC emulsion vs HSA) varied significantly with changes in the ratio of PFC emulsion to HSA. This could be important in terms of the different distribution of HSA and PFC emulsion in the body. Studies with PFC emulsion components indicated that any displacement of HSA-bound tamoxifen by the PFC emulsion was due to the oleic acid and, to a much smaller degree, Pluronic F-68 components. Other HSA site IV ligands are expected to be similarly displaced.

Effects of a perfluorochemical blood substitute on diazepam binding by human albumin.

The binding of 0.4 microgram mL-1 diazepam and 0.75 mol diazepam mol-1 of albumin by a perfluorochemical (PFC) emulsion, Fluosol-DA, 20%, by human serum albumin (HSA), and by their mixtures, has been examined at ambient temperature. The concentration of free diazepam was determined by standard centrifugation followed by supernatant ultrafiltration. Non-specific loss of diazepam occurred to the ultrafiltration device. This loss was independent of drug concentration and a correction factor was employed to calculate the true free diazepam concentration. Diazepam was extensively bound by the PFC emulsion. The percent free diazepam increased as the emulsion concentration decreased, while the binding of diazepam appeared to be independent of drug concentration. Diazepam did not partition into the pure PFC liquids, indicating that emulsion-bound diazepam is only associated with the emulsifiers of the droplets. Diazepam was extensively bound by HSA and the percent free diazepam increased as drug concentration increased or as HSA concentration decreased. The PFC emulsion significantly displaced HSA bound diazepam in all mixtures examined. Studies with the individual and combined components of the emulsion indicated that this displacement is largely attributed to the oleic acid component and, to a much smaller degree, the Pluronic F-68 component of the emulsion.

Lymphoid tissue responses to a novel perfluorochemical emulsion in rats

The effects of a novel perfluorochemical emulsion on rat lymphoid tissues and antibody production against sheep red blood cells (SRBC) have been studied. The responses were compared with those following injection of identical doses of the proprietary emulsion, Fluosol-DA 20% (F-DA). Liver weight was increased up to 15% at 8 days following intravenous (i.v.) or intraperitoneal (i.p.) injection of the novel emulsion but was unaffected by F-DA injection. Spleen weight also increased by a maximum of 20% in response to i.p. injection of the novel emulsion but this was less than increases of up to 44% which occurred in F-DA-injected rats. Thymus weight decreased (P less than 0.05) following i.p. injection of the novel emulsion whereas mesenteric lymph node (MLN) weight remained unchanged. However, MLN weight was increased in response to i.v. injected F-DA, while thymus weight showed a small increase following i.p. F-DA injection. Mean plasma antibody titres to SRBC were significantly (P less than 0.01) increased at 7 days after immunization in rats pretreated with i.p. injections of either the novel emulsion or F-DA; titres in animals pretreated with i.v. injections of either emulsion were similar to control.

Effect of a perfluorochemical emulsion on the rat hepatic mixed function oxidase system.

The perfluorochemical components of synthetic oxygen transporting emulsions may persist in hepatic tissue. After a single 30% blood exchange with the perfluorochemical emulsion, Fluosol-DA 20%, the effects on the microsomal metabolism of 7-methoxycoumarin and 7-ethoxycoumarin were studied over a 9-week period. Fluosol-DA treated animals were compared with controls (sham) and hetastarch-treated controls. Changes in dealkylase activities were compared with induction by phenobarbitone and 3-methylcholanthrene. The liver to body weight ratio increased by 49% in Fluosol-DA-treated rats over the controls at 1 week and the microsomal protein was increased in the Fluosol-DA-treated rats after 4 and 9 weeks. Fluosol-DA treatment induced 7-methoxycoumarin demethylase with peak differences occurring at 1 week and a Vmax 75% greater than controls. Fluosol-DA was a more potent inducer of demethylase than phenobarbitone. In addition, 7-ethoxycoumarin de-ethylase was induced by Fluosol-DA with a peak induction at 4 weeks. The Vmax at 4 weeks in Fluosol-DA-treated rats was 122% greater than control. In this case, Fluosol-DA produced less induction in de-ethylase than 3-methylcholanthrene. These studies show that Fluosol-DA induces more than one form of cytochrome P450 and the effects resemble those of phenobarbitone more than those of 3-methylcholanthrene. Hetastarch, a plasma expander, did not affect liver weights, microsomal protein content, or the cytochrome P450 system.

Assessment of A Novel Perfluorochemical Emulsion in Skin Protection Against Photodynamic Therapy in Mice

Assessment of A Novel Perfluorochemical Emulsion in Skin Protection Against Photodynamic Therapy in Mice

The use of a perfluorochemical emulsion as a vascular perfusate in drug absorption.

In-vitro simultaneous luminal and vascular perfusion using the perfluorochemical emulsion, FC-43 emulsion, as a vascular perfusate, was examined for drug absorption in rat jejunum. The intestinal membrane in this system was found to retain its normal barrier functions for drug transport, as evident from the following: (i) stable absorption clearance of tritiated water and salicylic acid at steady-state, (ii) agreement of this clearance with that by in-situ single-pass luminal perfusion, (iii) active transport of D-glucose and its inhibition by phloridzin and (iv) normal glutamate pyruvate transaminase activity in the intestinal mucosa. FC-43 emulsion gave a more normal absorption site blood flow than the usual vascular perfusate containing erythrocytes and albumin in Krebs-Henseleit bicarbonate buffer solution. Consequently, this emulsion was useful for examining the contribution of blood flow resistance toward drug absorption. The rate-limiting steps of absorption of tritiated water, antipyrine and salicylic acid were examined by perfusion using FC-43 emulsion. The absorption of tritiated water was almost completely blood flow-limited and its absorption clearance may possibly be an approximated absorption site blood flow. The contribution of blood flow resistance to total resistance for antipyrine absorption exceeded that for salicylic acid absorption.

Emulsified perfluorochemicals as respiratory gas carriers: recovery of perfluorodecalin emulsion droplets from rat tissues.

To further understand the in-vivo biokinetic behaviour of perfluorochemical (PFC) emulsions, male rats were injected (10 mL kg-1) with 30% (w/v) emulsified perfluorodecalin (FDC) and uptake into tissues assessed. At 72 h after injection, the mean (+/- s.e.m.) diameters of FDC droplets recovered from liver and spleen were 2.24 +/- 0.04 and 2.78 +/- 0.10 microns, respectively; droplets recovered from lung after 72 h (mean: 1.73 +/- 0.13 micron) were significantly smaller (P < 0.01). After 7 days, FDC droplet diameters in liver had increased to 3.31 +/- 0.13 microns (P < 0.01) and those in lung to 2.71 +/- 0.14 microns (P < 0.01); droplets in spleen after 7 days (2.22 +/- 0.09 microns) were similar to those at 72 h. These data support the hypothesis that significant initial coalescence of FDC droplets occurs in the rat liver and spleen, with further coalescence in the liver up to 7 days. The mean percentage of the injected FDC dose recovered from the liver after 72 h was 2.2 +/- 0.4%, and after 7 days was 0.07 +/- 0.05% (P < 0.01). A smaller decrease in the percent injected FDC in spleen also occurred over the same period (72 h: 1.9 +/- 0.3%; 7 days: 0.8 +/- 0.5%; P < 0.01). The percent injected FDC in lung was similar at 72 h (0.007 +/- 0.004%) and 7 days (0.005 +/- 0.001%). FDC was undetectable (< 0.001%) in all blood samples. The greater rate of FDC elimination from the liver than from the spleen may be related to differences in the rates of reticuloendothelial system processing between these organs.

Effects of perfluorochemicals for intrapulmonary vancomycin administration and partial liquid ventilation in an animal model of meconium-injured lungs.

Acute lung injury, such as meconium aspiration syndrome in neonates, may present with exacerbated ventilation and perfusion abnormalities. This can impair the efficacy of intravenous antibiotic therapy in treating pulmonary infection. Intrapulmonary administration via perfluorochemical as a vehicle may adequately deliver drugs, such as the poorly pulmonary-penetrative antibiotic vancomycin, to affect lung regions while maintaining gas exchange and non-toxic serum level. Twelve newborn piglets were injured with intra-tracheally installed human meconium, and randomly grouped into intravenous group (intravenous injection with vancomycin 15 mg/kg, followed by conventional gas ventilation) or intrapulmonary group (intrapulmonary instilled with vancomycin 15 mg/kg and perfluorochemical emulsion, followed by partial liquid ventilation). Blood samples were obtained to check vancomycin serum concentrations (0-240 mins). Lung tissues were tested for vancomycin contents. Intrapulmonary group animals had significantly lower vancomycin serum levels than the intravenous group, but vancomycin contents (198.9 +/- 72.5 microg/g dry tissue) in lung tissues was significantly higher than in the intravenous group (134.9 +/- 39.1 microg/g dry tissue) (p < 0.05). Gas exchange and lung compliance in the intrapulmonary group were also significantly better than in the intravenous group. Perfluorochemical is a good vehicle to deliver vancomycin and maintains gas exchange in severe meconium-injured lungs.

Quantifying the role of oxygen pressure in tissue function

it has been suggested that oxygen had reached significant levels in the earth's oceans as early as 2.5 billion years ago and has rapidly increased to near current levels about 50 million years later ([6][1]). The appearance of oxygen dramatically changed the chemical composition of the oceans and

Cardioprotective Effect of Perfluorochemical Emulsion for Cardiac Preservation after Six-Hour Cold Storage

Perfluoro-octyl bromide (PFOB) emulsion is capable of transferring oxygen to tissues even at 4 degrees C, suggesting an application in myocardial preservation. We evaluated the cardioprotective effect of PFOB emulsion added to the storage solution. Guinea pig hearts were isolated (n = 24) and perfused with Krebs-Henseleit solution (KHS) and then cooled and perfused with St. Thomas Hospital II solution (STS). The hearts were stored in three different solutions: STS (STS group), oxygenated (O2) STS (O2 STS group), and O2 STS with PFOB emulsion (30%) (O2 STS + PFOB group) for 6 hours at 4 degrees C. After storage, rewarming was performed, followed by reperfusion with KHS. Left ventricular developed pressure of O2 STS + PFOB group was significantly higher than that of the other groups during reperfusion (p < 0.01). There was no difference among the three groups in O2 extraction and cardiac efficiency; however, cardiac oxygen consumption in the O2 STS + PFOB group significantly improved during reperfusion. In the O2 STS + PFOB group, creatinine kinase, lactate dehydrogenase, and myocardial water content were significantly decreased (p < 0.01). This study suggests that PFOB emulsion is beneficial for the cardioprotection of donor hearts, allowing a prolonged cardiac storage time.

Reperfusion injury after critical intestinal ischemia and its correction with perfluorochemical emulsion "perftoran"

To investigate the anti-ischemic properties of perfluorochemical emulsion "perftoran" in mesenteric region. Experiments were conducted on 146 nonlinear white male rats weighing 200-350 g. Partial critical intestinal ischemia was induced by thorough atraumatic strangulation of 5-6 cm jejunal loop with its mesentery for 90 min. Global critical intestinal ischemia was made by atraumatic occlusion of the cranial mesenteric artery (CMA) for 90 min also. Perftoran (PF, 0.8-1.0 mL per 100 g) in experimental groups or 0.9% sodium chloride in control groups was injected at 75 min of ischemic period. Mean systemic arterial blood pressure (BP(M)) registration, intravital microscopy and morphological examination of ischemic intestine and its mesentery were performed in both groups. During 90 min of reperfusion, BP(M) progressively decreased to 27.3+/-7.4% after PF administration vs 38.6+/-8.0% in the control group of rats with partial intestinal ischemia (NS) and to 50.3+/-6.9% vs 53.1+/-5.8% in rats after global ischemia (NS). During the reperfusion period, full restoration of microcirculation was never registered; parts with restored blood flow had leukocyte and erythrocyte stasis and intra-vascular clotting, a typical "non-reflow" phenomenon. The reduction of mesenteric 50-400 mum feeding artery diameter was significantly less in the PF group than in the control group (24+/-5.5% vs 45.2+/-3.6%, P<0.05) 5 min after partial intestinal ischemia. This decrease progressed but differences between groups minimized at the 90(th) min of reperfusion (41.5+/-4.2% and 50.3+/-2.8%, respectively). In reperfusion of rat's intestine, a significant mucosal alteration was registered. Villous height decreased 2.5-3 times and the quantity of crypts decreased more than twice. In the group of rats administered PF, intestinal mucosal layer was protected from irreversible post-ischemic derangement during reperfusion. Saved cryptal epithelial cells were the source of regeneration of the epithelium, which began to cover renewing intestinal villi after 24 h of blood flow restoration. View of morphological alterations was more heterogeneous in CMA groups. Systemic administration of perftoran promotes earlier and more complete structural regeneration during reperfusion in rats after partial and global critical intestinal ischemia.

Liquid ventilation: an adjunct for respiratory management

Although significant advances in respiratory care have reduced mortality of patients with respiratory failure, morbidity persists, often resulting from iatrogenic mechanisms. Mechanical ventilation with gas has been shown to initiate as well as exacerbate underlying lung injury, resulting in progressive structural damage and release of inflammatory mediators within the lung. Alternative means to support pulmonary gas exchange while preserving lung structure and function are therefore required. Perfluorochemical (PFC) liquids are currently used clinically in a number of ways, such as intravascular PFC emulsions for volume expansion/oxygen carrying/angiography and intracavitary neat PFC liquid for image contrast enhancement or vitreous fluid replacement. As a novel approach to replace gas as the respiratory medium, liquid assisted ventilation (LAV) with PFC liquids has been investigated as an alternative respiratory modality for over 30 years. Currently, there are several theoretical and practical applications of LAV in the immature or mature lung at risk for acute respiratory distress and injury associated with mechanical ventilation.

Engineering blood: synthetic substitutes from fluorinated compounds.

Concerns about blood safety and the logistical problems associated with conventional transfusion have fuelled the search for effective alternatives (so-called blood substitutes). Such materials include hemoglobin derivatives and those based on synthetic, highly fluorinated, inert organic compounds called perfluorochemicals (PFCs). PFCs dissolve large volumes of oxygen and other gases, are unreactive in the body, and are excreted primarily as a vapor by exhalation. Liquid PFCs are immiscible with blood and other body fluids, but can be injected safely into the bloodstream as submicron emulsions. Emulsified PFCs have been evaluated in clinical trials as temporary, intravascular tissue-oxygenating fluids. One such emulsion, a commercial perflubron-based, phospholipid-stabilized formulation, is in advanced clinical trials as an alternative to transfusing donated (allogeneic) blood during surgery. Basic and clinical studies have shown that this emulsion can adequately maintain tissue oxygenation during acute blood loss with no abnormal hemodynamic changes. The use of PFC emulsions as an efficacious, short-term transfusion alternative underpins the longer term objective of producing a totally synthetic, bioengineered blood substitute.

The concept of hemoglobin equivalency of perfluorochemical emulsions.

Perfluorochemical (PFC) emulsions have been in development as intravenous oxygen carriers for a number of years and many publications have dealt with their oxygen transport characteristics in both experimental models and in clinical trials. Though it has been stressed on numerous occasions that PFCs deliver oxygen to the tissues in very different ways to those by which Hemoglobin (Hb) releases oxygen (O2), no serious attempts have been made to correlate the oxygen delivery capacity of PFCs to those of Hb. This paper presents theoretical ways in which this can be done and demonstrates that a 2.7 g/kg dose of PFC is approximately equivalent to 4 g/dL [Hb]. Clinical trial planning is discussed.

Evidence for stretch-induced resistance increase of proximal coronary microcirculation

We investigated the influence of stretch on regional hemodynamic parameters of the septal circulation. We used a similar experimental setup and mathematical model, as described previously (14). Five ventricular septa were isolated from anesthetized dogs, sutured to a biaxial stretching apparatus, and perfused with an oxygenated perfluorochemical emulsion at maximal vasodilation. Under unloaded and biaxially stretched conditions, flow and septal thickness (to index vascular volume) were measured continuously. Pressure was varied sinusoidally at 30, 50, and 70 mmHg with amplitude of 7.5 mmHg over frequencies ranging between 0.015 and 7 Hz. Admittance (flow/pressure) and capacitance (thickness/pressure) transfer functions were calculated and interpreted in terms of a two-compartmental model with volume-dependent resistances. Parameter estimation showed that the proximal resistance and compliance were unaffected, whereas the resistance of the proximal part of the microcirculation, including the small arterioles, increased with stretch. The effect of stretch on the distal resistance and capacitance, however, could not be determined unequivocally.

Dynamics of flow, resistance, and intramural vascular volume in canine coronary circulation.

Varying coronary volume will vary vascular resistance and thereby have an effect on coronary hemodynamics. Six ventricular septa were isolated from anesthetized dogs, dispersed in a biaxial stretch apparatus at diastolic stress, and perfused artificially with an oxygenated perfluorochemical emulsion at maximal vasodilation. Flow and thickness were measured continuously by an electromagnetic flow probe and sonomicrometer. Pressure was varied sinusoidally around 30, 50, and 70 mmHg with an amplitude of 7.5 mmHg; frequencies ranged between 0.015 and 7 Hz. Bode plots of admittance (flow/pressure) and capacitance (scaled thickness/pressure) were constructed. A two-compartment model was used in which the resistances vary with volume. Realistic values of microvascular compliance ( approximately 0.3 ml x mmHg(-1) x 100 g(-1)) were found. Values 10 times higher were then found when resistances were forced to be constant. We concluded that volume dependence of resistances have to be taken into account when dynamic or static pressure-flow relations are studied and conceal the effect of a large intramyocardial compliance on arterial hemodynamics.

The effect of a perfluorochemical emulsion on enzyme reaction stability

AbstractA reaction system consisting of (oxygen‐consuming) tyrosinase immersed within a perfluorochemical emulsion was investigated by comparing the activity and stability of the enzyme within the emulsion to that within pure buffer. The perfluorochemical emulsion contained 30 v/v% perfluorooctane, 70 v/v% aqueous buffer and pluronic‐F68 as a surfactant. The catecholase activity of soluble mushroom tyrosinase was chosen for study and catechol was used as a substrate. A turnover parameter of 0.50 absorbance units and an inactivation rate constant of 0.012 s−1 were found in the presence of a perfluorochemical emulsion and a turnover parameter of 0.53 absorbance units and an inactivation rate constant of 0.012 s−1 were found in the absence of perfluorochemicals (pure buffer). The enzyme demonstrated no appreciable loss in performance within the perfluorochemical emulsion relative to its behaviour within aqueous buffer. This implies that the local concentrations of oxygen are the same under both systems and that under conditions when oxygen is limited in an aqueous system, tyrosinase performance would be improved within the perfluorochemical medium.

Effects of a perfluorochemical emulsion on the fate of circulating Pseudomonas aeruginosa.

Because mononuclear phagocytes take up perfluorochemical emulsions (PFCE), we examined how prior treatment with PFCE affects the fate of circulating bacteria. Rats were preinjected with three daily intravenous injections of PFCE (2.0 ml/100 g) containing 12.5% (vol/vol) of a 4:1 mixture of F-dimethyl adamantane and F-trimethylbicyclo-nonane, 2.5% (wt/vol) Pluronic F-68 as the emulsifying agent, and 3% (wt/vol) hydroxyethyl starch as the oncotic agent. Pseudomonas aeruginosa or Staphylococcus aureus were injected 4 h after the third PFCE injection. PFCE pretreatment decreased the rate and extent of vascular clearance of P. aeruginosa, with decreased uptake by the liver. Importantly, there were significant decreases in killing of P. aeruginosa in the liver, lungs, spleen, and kidneys of PFCE animals. PFCE did not alter the clearance of S. aureus from the circulation. However, hepatic uptake was reduced, with concomitant increases in lung and kidney uptake. Ultrastructure of Kupffer cells revealed PFCE inclusions and extensive vacuolization. These experiments demonstrate that the clearance kinetics and organ distribution of circulating P. aeruginosa and their subsequent killing are altered by PFCE. Diminished hepatic phagocyte function leads to a decrease in vascular clearance of circulating bacteria, increased uptake in other reticuloendothelial organs, and decreased bactericidal activity versus P. aeruginosa.