Search PubMed⌕ Search

SEARCH · Search PubMed

Results for “EMULSIONS”

Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 199 records · Page 11Linked to original sources
PubMedDate not supplied

Blood clearance and tissue uptake of intravenous lipid emulsions containing long-chain and medium-chain triglycerides and fish oil in a mouse model.

BACKGROUND: Increasing interest in using different triglycerides (TGs) for specific clinical applications raised the question as to how the emulsion TG composition would affect blood clearance and emulsion delivery to hepatic and extrahepatic tissues. METHODS: Emulsions used were long-chain soy oil TG (long-chain triglyceride [LCT]), LCT/ medium-chain triglyceride (MCT; 1:1, wt/wt), LCT/MCT/C/omega-3 (5:4:1, wt/wt) and pure fish oil (omega-3 TG) labeled with non-degradable 3H-cholesteryl oleoyl ether (3H-CE) as a particle marker. Mice (C57BL/6J) were injected with four different commercial emulsions at a nonsaturating dose of 0.4 mg TG/20 to 25 g per mouse to obtain 1st order kinetics. Blood was sampled at 0.5, 2, 5, 10, 15, and 25 minutes, and the fractional catabolic rate was determined by fitting a straight line to the logarithm of the blood 3H-CE radioactivity. Retention of 3H-CE for each tissue at 25 minutes reflected organ uptake of the emulsion. RESULTS: Blood clearance of pure omega-3 TG (10.40% +/- 0.54% pools/h; mean +/- SE) was significantly slower than that of LCT, LCT/MCT, and LCT/MCT/omega-3 emulsion (18.9 +/- 0.6 pools/h, 17.0 +/- 0.96 pools/h, 16.5 +/- 1.08 pools/h, respectively) (p < .01). Based on 3H-CE uptake, LCT, LCT/MCT, and omega-3 TG emulsions showed similar delivery to liver (39% +/- 3.9%, 46% +/- 3.6%, 34% +/- 3.2%). Liver uptake of LCT/MCT/omega-3, (23% +/- 2.2%) was less than LCT/MCT (46% +/-3.6%, p < .0001) and LCT (39% +/- 3.9%, p = .002). CONCLUSIONS: Results indicate slow blood clearance of pure omega-3 TG emulsion from the blood compared with emulsion in which omega-3 TG was mixed with LCT and MCT. Earlier data showed that omega-3 TG are poorly hydrolyzed in extracellular media and therefore are delivered to tissues as part of the core of emulsion remnants. Thus, our data suggest that the incorporation of omega-3 TG with LCT/MCT will result in greater delivery of omega-3 fatty acids to extrahepatic tissue, which could be important in modulating immune and other responses.

Animals↗
PubMed2000

Prevention of murine influenza A virus pneumonitis by surfactant nano-emulsions.

Non-ionic surfactant nano-emulsions have extensive anti-microbial activity and are biocompatible with skin and mucous membranes at effective concentrations. Two nano-emulsion formulations (8N8 and 20N10) made from soybean oil, tributyl phosphate and Triton X-100, were tested for their ability to prevent murine influenza virus pneumonia in vivo. In the initial study, CD-1 mice were administered various dilutions of the nano-emulsions intranasally, and safe dosages and concentrations were determined. Non-toxic concentrations of the nano-emulsions were then mixed with influenza virus and applied to the nares of mice. Animals receiving mixtures of two different emulsions (8N8 or 20N10) and a LD50 of virus survived the challenge without evidence of viral infection. To determine if the nano-emulsions could prevent influenza virus infection in vivo when used as a prophylactic treatment, the nano-emulsions (8N8 at 1.0% and 20N10 at 1.0% or 0.2%) were applied to mouse nares 90 min before exposure to 5x10(5) p.f.u./ml virus by nebulized aerosol. Animals pretreated with the nano-emulsions had significantly decreased clinical signs of infection. Only 26.0% (8N8 at 1.0%), 31.25% (20N10 at 1.0%) and 37.0% (20N10 at 0.2%) of animals pretreated with nano-emulsion died from pneumonitis, whereas >80.0% of mock pretreated animals succumbed to infection (P<0.005). These findings suggest that non-ionic surfactant nano-emulsions have therapeutic potential for the prevention of influenza virus infection in vivo.

Animals↗
PubMed1998

Prolonged release of tegafur from S/O/W multiple emulsion.

To develop a prolonged and sustained release preparation, we prepared an albumin microsphere-in-oil-in-water emulsion (S/O/W) and examined sustained release from it in comparison with other control preparations such as water-in-oil (W/O) emulsions and microspheres in vitro and in vivo, respectively. Tegafur was used as a model drug. A microsphere-in-oil emulsion was prepared by adding albumin microspheres to soybean oil containing 20% Span 80. To prepare an S/O/W emulsion, the microsphere-in-oil emulsion was added into an aqueous solution of hydroxypropyl methylcellulose containing Pluronic F68. The mean particle size of the albumin microspheres was 3 microns, and the ratio of entrapment of tegafur into albumin microspheres was about 25%. In an in vitro release test, the t75 of the S/O/W emulsion was fourfold greater and in an in vivo release test the mean residence time of tegafur from the S/O/W emulsion was more than twofold that from a W/O emulsion or microsphere system. The mean residence time of 5-fluorouracil (5-FU) from an S/O/W emulsion was also greater than with other dosage forms. These results suggest the possible usefulness of an S/O/W emulsion for the sustained and prolonged release of tegafur.

Animals↗
PubMed1994

Effects of buffer pH and phosphate concentration on the droplet size and EYP hydrolysis of perflubron/EYP emulsions.

Oil-in-water emulsions containing perflubron (perfluorooctyl bromide; PFOB) and stabilized with egg yolk phospholipid (EYP) have potential applications as contrast agents and oxygen carriers. In this study, the effects of buffer pH and total phosphate concentration on the emulsion droplet size and EYP hydrolysis were evaluated. 90% w/v perflubron emulsions with NaH2PO4-Na2HPO4 buffers of different pH (4.7-8.7) and phosphate concentrations (30 and 60 mM) were prepared with a high-pressure homogenizer. Emulsions were stored at 40 degrees C and tested at 0, 1, 2 and 3 months. The pH dropped quickly in emulsions with pH 8.7 buffer whereas acidic and neutral buffered emulsions exhibited minor pH drops. The concentration of free fatty acids (FFA) vs emulsion pH can be fitted to a parabolic curve with a minimum at about pH 6.0. The droplet growth rates in emulsions with the pH 4.7 buffer were about 2.5 times of those in emulsions with the pH 8.7 buffer. Total phosphate concentration had only a minor effect. This study emphasizes the importance of the careful selection of buffer pH and capacity to control EYP hydrolysis and possibly emulsion droplet size.

Buffers↗
PubMed1975

Effect of fluorocarbon emulsions on the mechanical fragility of normal and sickle cells: in vitro studies.

Mechanical fragility measurements have been made in vitro on fluorocarbon emulsions mixed with normal and sickle cells in plasma to determine the effect of fluorocarbon. Emulsions of FC-80 with Pluronic F-68 were added to give final solutions of 0, 1, 5, 10, and 20% fluorocarbon emulsion. The effect of the fluorocarbon emulsion was observed in the presence and absence of oxygen. In the presence of oxygen, there was no effect of the fluorocarbon emulsion on the mechanical fragility of normal or sickle cells. In deoxygenated systems, however, there was significantly less hemoglobin in the plasma during the mechanical fragility test with fluorocarbon emulsion added to sickle cell blood. The normal blood was not affected by the fluorocarbon emulsion in the deoxygenated system. Five percent of fluorocarbon emulsion was required for a significant effect on the deoxygenated sickle cells. Since the effect of the fluorocarbon emulsion was in a deoxygenated condition, the effect is due to the presence of the fluorocarbon emulsion and not its oxygen carrying capability.

Anemia, Sickle Cell↗
PubMed1991

Monensin in lipid emulsion for the potentiation of ricin A chain immunotoxins.

The utilization of carboxylic ionophores such as monensin for immunotoxin potentiation may be hampered by the poor solubility and short in vivo half-life of these highly lipophilic compounds. Therefore, the use of monensin formulated in a lipid/water emulsion was investigated for the in vitro and in vivo potentiation of immunotoxins. Monensin in emulsion or in buffer was equally effective for the in vitro potentiation of the cytotoxicity of both anti-human transferrin receptor and anti-carcinoembryonic antigen immunotoxins against target cells. In mice, buffer and lipid emulsion were compared as vehicles for the i.p. administration of monensin. The half-life of monensin in the peritoneal cavity of BALB/c x DBA/2 F1 (CD2F1) mice was increased 20-fold by inclusion in lipid emulsion (13 min versus 0.75 min). Treatment i.p. with anti-human transferrin receptor immunotoxin or anti-carcinoembryonic antigen immunotoxin and monensin emulsion prolonged the survival of mice with macroscopic i.p. tumor xenografts of H-Meso-1 mesothelioma and LS174T colorectal carcinoma (200-250% increased length of median survival). The in vivo antitumor effect of the cell-specific immunotoxin plus monensin emulsion was superior to immunotoxin alone or to immunotoxin plus monensin in buffer (P less than 0.03; Mann-Whitney U test). This indicates that delivery of monensin in preformed lipid emulsion may produce a reservoir effect of the ionophore in the peritoneal cavity of tumor-bearing mice. Nonspecific control immunotoxin plus monensin emulsion produced no increase in survival. Long-term tumor-free survival (greater than 150 days versus a median survival of 25 days for controls) of mice bearing microscopic LS174T xenografts was obtained by treatment with anti-human transferrin receptor immunotoxin plus monensin emulsion. Administration of either monensin in buffer or monensin in emulsion without immunotoxin had no significant effect on survival. Monensin in this pharmacologically available form significantly improved the in vivo efficacy of both anti-human transferrin receptor immunotoxin and anti-carcinoembryonic antigen immunotoxin when used as regional therapy.

Animals↗
PubMed1988

Effect of different molecular species of phosphatidylcholine on the clearance of emulsion particle lipids.

Studies were performed to assess the effect of changes in the molecular species composition of phosphatidylcholine (PC) on the clearance of emulsion particles that were made to approximate chylomicrons in size and lipid composition. Emulsions were prepared with free [14C]cholesterol, [3H]cholesteryl oleate, triolein, and one of four single PCs that differed in hydrophilic strength (as assessed by the relative rate of elution of these PCs from a reverse phase column). Emulsions were injected as an intravenous bolus into unanesthetized rats and the clearance of lipids was determined at 2-min intervals for 10 min. All emulsion lipids were cleared from the serum in parallel and in an order that closely corresponded to the relative hydrophilic strength of the particular PC that was administered. Fractional rates of clearance, calculated from log-linear plots, were 2- to 10-fold greater for all lipids for the emulsion that was made with the most hydrophilic PC compared to the least hydrophilic PC. Although hepatectomy, performed in acutely anesthetized animals, generally slowed the clearance of lipids, hepatectomy did not abolish differences in the clearance of triolein or specific PCs from emulsions prepared with the most and least hydrophilic PCs. These results indicate that a change in the composition of emulsion particle PCs, independent of any other change in the lipid composition of these particles, can significantly change the metabolism of the whole emulsion particle in the live animal. More specifically, these studies show that the rate of clearance of all emulsion lipids closely corresponds to the hydrophilic strength of the PCs that occupy the emulsion particle surface.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1986

Effects of exogenous fat emulsion (Intralipid) on chemotactic function of monocytes and polymorphonuclear cells in sepsis.

Effects of exogenous fat emulsion (Intralipid) on the chemotactic function of monocytes and polymorphonuclear (PMN) cells were studied in vivo with rats. Abdominal sepsis was induced in Sprague Dawley rats by cecal ligation and puncture. Following a bolus infusion of the fat emulsion or saline, chemotactic function of monocytes and PMN cells was evaluated in animals divided into the following four groups: Group I, non-septic rats receiving saline infusion (NS-S); Group II, non-septic rats receiving the fat emulsion (NS-F); Group III, septic rats receiving saline (S-S); Group IV, septic rats receiving the fat emulsion (S-F). Results of the study revealed that monocyte function was suppressed by the sepsis, whether saline or the fat emulsion was infused, and administration of the fat emulsion resulted in suppression of monocyte chemotaxis both in the non-septic and the septic rats. Although in this study chemotactic function of PMN cells was not significantly suppressed by the sepsis, administration of the fat emulsion again led to a suppression of PMN cell function, in both the non-septic and the septic rats. Results of the study confirmed that administration of an exogenous fat emulsion may suppress the chemotactic function of the monocytes and PMN cells and, in the presence of severe sepsis, infusion of the fat emulsion may lead to a further deterioration of immunologic function of the host. Special care, therefore, should be taken against the use of exogenous fat emulsion in septic individuals or in those at risk of infection.

Animals↗
PubMedDate not supplied

Particle size reduction of emulsions by formulation design-II: effect of oil and surfactant concentration.

The objective of this study was to investigate the effect of the concentration of surfactant and oil on particle size reduction and stability of oil-in-water emulsion formulations containing polyhydroxy alcohols. Emulsions were prepared using an emulsifier system consisting of Tween 80 and Span 80 with 5%, 10%, 15% and 20% soybean oil and containing 50% w/w of either propylene glycol (PG) or glycerol (GLY) in the external phase. At each oil concentration, four emulsions were formulated with increasing surfactant concentration to provide emulsions with surfactant to oil (S/O) ratios of 0.1, 0.2, 0.3 and 0.4. Three parameters were evaluated, particle size reduction, particle size stability upon dilution, and viscosity. It was found that increase in S/O ratio resulted in substantial decrease in particle size in all cases. But there was a difference in the particle size reduction pattern between PG and GLY. Increase in oil concentration at the same S/O ratio caused particle size reduction for emulsions with PG but not for emulsions with GLY. The reduction in particle size was also greater for emulsions containing PG. Further, particle size of emulsions containing PG was found to be stable over 24 hours after dilution. However, a slight increase in particle size was observed in emulsions containing GLY. It was also found that the viscosity of emulsions increased with an increase S/O ratio as well as the concentration of the oil.

Drug Compounding↗
PubMed1995

Intravenous lipid emulsions: removal mechanisms as compared to chylomicrons.

We have compared the metabolism of chylomicrons and a labeled emulsion, similar to those used for parenteral nutrition. Both were labeled in their triglyceride moieties and by a core label. It is known that chylomicron triglycerides are cleared by two processes: removal of triglycerides from the particles through lipolysis and removal of whole or partly lipolyzed particles. It has been proposed that emulsion droplets are cleared by the same pathways. After intravenous injection to postprandial rats, triglycerides were cleared less rapidly from the emulsion than from the chylomicrons (half-lives of 6.4 and 4.0 min), whereas the core labels were cleared at the same rate (half-lives around 7.5 min). This suggests that there was less lipolysis of the emulsion droplets which was further supported by the finding that less label appeared in the plasma free fatty acids (FFA). In adipose tissue of fed rats given chylomicrons, the ratio between fatty acid and core label was above 6, showing that fatty acids had been taken up after lipoprotein lipase-mediated hydrolysis. In contrast, for rats given emulsion, that ratio was only 1.2 showing that nearly as much emulsion droplets as emulsion-derived fatty acids were present in the tissue. In the liver the ratio was 0.55 after chylomicrons but 0.93 after emulsion. In further support of more lipolysis, fatty acids were oxidized more rapidly from chylomicrons than from emulsion. These data suggest that a large fraction of the emulsion droplets was removed from plasma with little or no preceding lipolysis. A substantial proportion, more than 50%, of this uptake occurred in extrahepatic tissues.

Animals↗
PubMed1997

Particle size determines the specificity of apolipoprotein E-containing triglyceride-rich emulsions for the LDL receptor versus hepatic remnant receptor in vivo.

Apolipoprotein E (apoE) is an important determinant for the uptake of triglyceride-rich emulsions and lipoproteins by the liver, and exerts affinity for both the LDL receptor (LDLr) and a distinct liver-specific recognition site. Our current aim was to assess the mechanism underlying the receptor-specificity of apoE-carrying lipoproteins. Triglyceride-rich emulsions were synthesized, with mean sizes of 50, 80, and 150 nm. These fractions efficiently acquired apoE from rat serum, and were processed by LPL in vivo with a similar efficiency. Upon injection of the [5H]cholesteryl oleate-labeled emulsions into rats, the liver association rate was positively correlated with particle size (24 +/- 2%, 54 +/- 1%, and 64 +/- 3% of the injected dose at 20 min after injection, respectively) and the liver uptake was predominantly exerted by parenchymal cells. The role of the LDLr in emulsion clearance was established in wild-type versus LDLr knockout mice. In the absence of the LDLr, an 8-fold increased serum half-life was observed for the small emulsion, concomitant with a 6- and 15-fold decreased uptake by the liver and adrenals at 60 min after injection, respectively. In contrast, the in vivo behavior of the large emulsion was independent of the LDLr. Both the ratio of apoE:C on the emulsions upon serum incubation and the alpha-helical content of apoE were inversely correlated with particle size, indicating that these factors may be involved in the emulsion size-dependent receptor specificity in vivo. It is concluded that the contribution of the LDLr to the apoE-mediated clearance of emulsions by the liver and adrenals strongly increases with decreasing particle size, while large particles initially associate with a distinct liver-specific recognition site. As these emulsions mimic chylomicrons, we anticipate that the apoE-dependent metabolic behavior of chylomicrons (remnants) is largely dependent on their size.

Animals↗
PubMedDate not supplied

Effect of infusing fat emulsion into extracorporeal membrane oxygenation circuits.

Our objectives were to identify problems associated with the administration of fat emulsion by extracorporeal membrane oxygenation (ECMO) circuits, and gather information from other institutions on standards of practice and the complications associated with infusion of fat emulsion by ECMO to infants and children. In vitro analysis was performed using six circuits. Fat emulsion was infused into a prereservoir port at 3 ml/hour. Circuits and blood samples collected distal to the oxygenator were inspected visually for layering (separation of fat emulsion from blood), agglutination, and phase separation (formation of an oil layer) at 0.5, 1, 2, 4, 6, 12, and 24 hours. At 24 hours, samples were reevaluated and circuits dissected. All circuits showed layering and agglutination. Blood clots were present in five circuits during the simulation. There was no evidence of phase separation in the samples. Adhesion of emulsion to the equipment was present in all circuits. Five of the membrane oxygenators contained clots. One contained long strands of fat; separation of its mesh revealed an oily residue indicating disruption of the stability of the emulsion. Survey responses from 54 centers found that 78% used fat emulsion routinely in neonatal or pediatric patients receiving ECMO. Most used both ECMO and separate venous access for the infusion, depending on availability. Twenty-two (52%) of the 42 centers using fat emulsion had a policy in place regarding site selection. Of those, 73% preferred central venous access, another 18% used a prereservoir port of the ECMO circuit. The most frequently reported problems with administration through the circuit were cracking of stopcocks, clogging and malfunction of the membrane oxygenator, agglutination of the emulsion, and increase in blood clot formation. Our results suggest that fat emulsion should be infused through a separate intravenous site whenever possible. Based on these results and current practices of most ECMO centers, a clinical trial is currently being conducted to provide additional information.

Blood Coagulation↗
PubMed1997

The myoneural effects of propofol emulsion (Diprivan) on the nerve-muscle preparations of rats.

The potential effects of propofol emulsion (Diprivan) on the neuromuscular transmission and muscular contraction were studied using in vitro and in vivo nerve-muscle preparations of rats. The contractions of the isolated rat diaphragm elicited by either indirect or direct electrical stimulation were inhibited by propofol emulsion at threshold concentrations of 42 and 112 mumol l-1, respectively. Similarly, the gastrocnemius muscle contractions induced by either indirect or direct electrical stimulation in vivo were inhibited by propofol emulsion administration as a bolus injection of 2.5 mg kg-1 intravenously, followed by intravenous infusion of 150 micrograms kg-1 min-1 for 1 h into rats. The inhibitory effects of propofol in both preparations were greater with indirect rather than direct stimulation. Propofol emulsion was found to be capable of enhancing the paralysis of the indirectly stimulated rat diaphragm in vitro and gastrocnemius muscle in vivo induced by either pipecuronium or succinylcholine. The combination of propofol and pipecuronium led to a synergistic inhibition of the neuromuscular transmission, while the combination of propofol and succinylcholine led to additive inhibition. Pretreatment with propofol emulsion at these threshold concentrations markedly inhibited the stimulant effects of aminophylline and digoxin on the indirectly and directly induced diaphragmatic contractions. Also, the enhancement effects of aminophylline on the indirectly and directly and of digoxin on indirectly induced rat gastrocnemius muscle contractions were markedly inhibited by propofol emulsion administration to rats. Pretreatment with propofol emulsion at the threshold concentrations enhanced the inhibitory effects of verapamil on diaphragmatic contractions elicited either indirectly or directly and enhanced the inhibitory effect of adenosine on the contractions elicited indirectly. Similarly, the inhibitory effects of verapamil on the indirectly and directly and of adenosine on indirectly induced rat gastrocnemius muscle contractions were markedly potentiated by propofol emulsion administration to rats. In addition, doubling the concentration of calcium in the bathing fluid produced no change in the inhibitory effects of propofol emulsion on either indirectly or directly elicited diaphragmatic contractions, while doubling the concentration of external magnesium potentiated the propofol effects. Pretreatment with 4-aminopyridine suppressed the inhibitory effects of propofol emulsion on diaphragmatic contractions elicited either indirectly or directly. These results suggest that propofol acts presynaptically to inhibit the neuromuscular transmission and acts at the muscle membrane to inhibit the muscular contraction.

Anesthetics, Intravenous↗
PubMed1997

Lipoprotein metabolism during and after a 6-h infusion ofMCT/LCT vs LCT emulsion in man.

We studied, in man, the intravascular metabolism of two lipid emulsions differing in their triglyceride (TG) fatty acid pattern. One emulsion was composed exclusively of soy bean long-chain triglycerides (LCT), the other of a mixture containing a (1:1, wt:wt) ratio of medium-chain triglycerides (MCT) and LCT (MCT/LCT). Both emulsions contained 10% TG and 1.2% of the same egg yolk phospholipid emulsifier. Six healthy volunteers received both emulsions, in random order, at a rate of 0.2 g TG/kg.h for 6 h. An interval of 2 weeks separated the tests. Although the MCT/LCT emulsion provided 39% more TG molecules than the pure LCT emulsion, plasma TG increased to similar levels, indicating a faster elimination of MCT/LCT. The rise of plasma non esterified fatty acids was greater with MCT/LCT (P < 0.001). LDL-TG enrichment was higher with MCT/LCT (P < 0.025) while net transfer of TG to HDL was similar with both emulsions. Cholesteryl ester (CE) enrichment in the 'VLDL' fraction (largely composed of emulsion particles) was markedly less during MCT/LCT than LCT infusions (P < 0.01). CE enrichment of the 'VLDL' fraction persisted up to 6 h after cessation of both lipid infusions. In conclusion, TG from MCT/LCT emulsion appear to be eliminated faster than LCT during an in vivo infusion in man. In accordance with our previous in vitro data, MCT/LCT infusion was associated with a higher transfer of TG to LDL and in a reverse manner, with a lesser acquisition of CE by emulsion particles as compared to LCT infusion.

Journal Article↗
PubMed2001

Filler effects of oil droplets on the rheology of heat-set emulsion gels prepared with egg yolk and egg yolk fractions.

Hen egg yolk is a traditional ingredient used in a wide variety of food emulsions, especially fluid sauces. Industrial processing of these sauces generally involves heat treatments in order to pasteurise or sterilise them. These heat treatments may cause undesired gelation of the emulsion, because egg yolk proteins are particularly thermosensitive. Heat gelation of oil-in-water emulsions prepared with egg yolk may differ from that of egg yolk solutions, because of the influence of oil droplets on network formation. In this study, we investigated the influence of oil droplets on the gelation of oil-in-water emulsions made with yolk. We studied three pH values: 3.0, 5.0 and 7.0 with a constant NaCl concentration: 0.55 M. Oil droplet size was controlled after emulsification, gelation of solutions and emulsions was monitored in situ by coupling heating with recording viscoelastic properties, and transmission electron microscopy was conducted in heat-set emulsion gels. In an attempt to target the proteins that impose the kinetic of gelation of egg yolk, we repeated the experiment with plasma and granules, the main fractions of yolk. In situ rheology showed that, in our experimental conditions [especially oil volume fraction (0.3) and oil droplet size (d3.2=1 &mgr;m)], emulsions made with yolk and plasma have a similar gelation process with oil droplets acting as inactive fillers. Furthermore, transmission electron microscopy showed similar network characteristics between heated emulsions made with yolk and plasma. Moreover, we demonstrated that acidic conditions provided the fastest gelation of yolk solutions and emulsions. On the other hand, in emulsions prepared with granules, oil droplets behaved as active filler particles and reinforced the gel strength.

Journal Article↗
PubMed2000

Influence of calcium, magnesium, or potassium ions on the formation and stability of emulsions prepared using highly hydrolyzed whey proteins.

Oil-in-water emulsions (4 wt % soy oil) containing 4 wt % whey protein hydrolysate (WPH) (27% degree of hydrolysis) and different levels of calcium, magnesium, or potassium chloride were prepared in a two-stage homogenizer. Other emulsions containing 4 wt % WPH but including 0.35 wt % hydroxylated lecithin and different levels of the above minerals were similarly prepared. The formation and stability of these emulsions were determined by measuring oil droplet size distributions using laser light scattering and by confocal scanning laser microscopy and a gravity creaming test. Both lecithin-free and lecithin-containing emulsions showed no change in droplet size distributions with increasing concentration of potassium in the range 0-37.5 mM. In contrast, the diameter of emulsion droplets increased with increasing calcium or magnesium concentration >12.5 mM. Emulsions containing hydroxylated lecithin were more sensitive to the addition of calcium or magnesium than the lecithin-free emulsions. Storage of emulsions at 20 degrees C for 24 h further increased the diameter of droplets and resulted in extensive creaming in emulsions containing >25 mM calcium or magnesium. It appears that both flocculation and coalescence processes were involved in the destabilization of emulsions induced by the addition of divalent cations.

Calcium↗
PubMed1991

Influence of the 100% w/v perfluorooctyl bromide (PFOB) emulsion dose on tumour radiosensitivity.

The radiosensitizing effect of a 100% w/v emulsion of a fluorocarbon, PFOB, which carries 4 times more oxygen than does Fluosol-DA 20% emulsion, was studied on two human tumour xenografts (HRT18 and HT29) and the murine tumour EMT6. This effect was compared with that obtained with carbogen alone. The fluorocrit (amount of fluorocarbon in the blood) and haematocrit remained unchanged from 7 to 65 min post-injection of the emulsion (8 ml/kg). Tumour-bearing mice were pretreated with 100% w/v PFOB emulsion doses ranging from 2 to 15 ml/kg in the presence of carbogen for 30 min prior to and during irradiation. The fluorocrit increased from 1.5% to 9.5% as the dose of 100% w/v PFOB emulsion increased from 2 to 15 ml/kg. The haematocrit remained the same for all the fluorocarbon emulsion doses used. Tumour radiosensitization varied with the fluorocarbon emulsion dose. Clinically relevant doses (2-4 ml/kg) of the 100% w/v PFOB emulsion plus carbogen produced significantly more radiosensitization than carbogen alone, with sensitizing enhancement ratios of 1.4 for EMT6 and 1.7 for HRT18. The radiosensitivity of HRT18 cells was thus very close to that obtained with normally oxygenated cells. For higher doses (8-15 ml/kg) the radiosensitizing effect of 100% w/v PFOB emulsion plus carbogen becomes comparable to that of carbogen alone. These experiments show that clinically useful doses of 100% w/v PFOB plus carbogen produced tumour radiosensitization only at relatively low fluorocrits. Thus the fluorocrit, and hence the fluorocarbon's oxygen-carrying capacity, is not the only factor involved in radiosensitizing tumour cells by oxygen-carrying fluorocarbon emulsions.

Adenocarcinoma↗
PubMed1992

Effect of a high concentration perfluorocarbon emulsion on platelet function.

Perfluorocarbon (PFC) and lipid emulsions (eg. Fluosol, Intralipid,) containing phospholipid have been reported to modify platelet function after intravenous infusion. Platelet activation might be responsible for the generation of mediators responsible for PFC-induced side effects. In view of this, we investigated the effect of a highly concentrated perfluorocarbon emulsion containing 90% (w/v) perfluorooctylbromide (perflubron; PFOB), on porcine and human platelet activation and function. We measured both: a) stimulated ex-vivo porcine platelet aggregation pre and post infusion of either perflubron or control (vehicle only) emulsions, and b) stimulated in vitro human platelet calcium flux in the presence of perflubron emulsion or control emulsions. Platelet aggregation stimulated by collagen, ADP or arachidonic acid (AA) was inhibited in ex-vivo porcine platelets following infusion of perflubron emulsion at a dose of 3 ml/kg (0.2 ml/kg/min). Inhibition was dose dependent and was decreased when the dose of perflubron emulsion was reduced to 1.0 or 0.3 ml/kg. Infusion of saline or "vehicle" emulsions had little or no effect on stimulated ex-vivo pig platelet aggregation. Fluosol, infusion was associated with inconsistent inhibition of platelet aggregation. A23187- or AA-stimulated calcium flux of human platelets in vitro was inhibited in the presence of 1% (v/v) perflubron emulsion. Similar effects were seen with Fluosol, or Intralipid. This inhibition was agonist dose-dependent.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗