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At least 253 records · Page 14Linked to original sources
PubMed1997

Emulsion formulation reduces propofol's dose requirements and enhances safety.

BACKGROUND: Propofol, a highly lipophilic anesthetic, is formulated in a lipid emulsion for intravenous use. Propofol has brisk onset and offset of effect after rapid administration and retains rapid offset characteristics after long-term administration. The authors tried to determine whether the emulsion vehicle is requisite for propofol's evanescent effect-time profile. METHODS: The time course of sedation and electroencephalographic (EEG) effect after propofol administration was measured in three studies in rats instrumented. In study 1, propofol was infused in either emulsion or lipid-free vehicle (n = 12), in a repeated measures cross-over design. In study 2, propofol in lipid-free vehicle was infused with or without simultaneous infusion of drug-free lipid emulsion (n = 6) in a repeated measures cross-over design. In study 3, propofol was infused in either emulsion (n = 5) or lipid-free vehicle (n = 5) to EEG burst suppression. RESULTS: In study 1, relative to the emulsion formulation, propofol administered at equivalent doses in lipid-free vehicle resulted in a longer time to effect onset (1.4 +/- 0.2 vs. 0.5 +/- 0.1 min, EEG) and a trend for delayed anesthetic recovery (26.8 +/- 9.4 vs. 17 +/- 3.5 min, EEG; 26.1 +/- 8.8 vs. 16.8 +/- 3.3 min, sleep). In study 2, coadministration of drug-free emulsion with propofol did not alter the time course of effect. In study 3, more than twice the dose of propofol was required to achieve EEG burst suppression with the lipid-free formulation. Two animals died after administration of propofol to EEG burst suppression with the lipid-free formulation; no deaths occurred in the emulsion group. CONCLUSION: The incorporation of propofol in emulsion reduces dose requirements and produces rapid onset and recovery of anesthetic effect.

Anesthetics, Intravenous↗
PubMed2005

Evaluation of tributyrin lipid emulsion with affinity to low-density lipoprotein: pharmacokinetics in adult male Wistar rats and cellular activity on Caco-2 and HepG2 cell lines.

The tributyrin lipid emulsion was proved to be able to bind to low-density lipoprotein (LDL) in vitro. The aim of this study was to investigate the pharmacokinetics of the emulsion in vivo and the cellular activity in vitro. The pharmacokinetics of tributyrin and its metabolite, butyrate, was evaluated in male Wistar rats after administration with pure tributyrin or tributyrin emulsion. After oral administration, maximal plasma concentration (C(max)), time to reach maximal plasma concentration (T(max)), and elimination half-life (T(1/2)) of butyrate were 87.6 muM and 25.3 and 63.0 min, respectively, for the pure tributyrin compared with 1344.5 microM and 8.5 and 19.8 min for the 10% (v/v) tributyrin emulsion. C(max) and mean residence time of tributyrin were 2.74 microM and 87.9 min and 4.2 microM and 132.0 min for pure tributyrin and 10% emulsion, respectively. The bioavailabilities of the pure tributyrin versus tributyrin emulsion were 15.3 versus 65.7% and 34.9 versus 64.5% calculated from butyrate and tributyrin, respectively. After the rats were treated with 17alpha-ethynylestradiol (an LDL receptor up-regulator), the distribution volumes calculated from both butyrate and tributyrin were significantly increased after oral administration or infusion of the 10% tributyrin emulsion. The increased distribution volume after coadministration with a LDL receptor up-regulator suggested the increased uptake of tributyrin/butyrate by tissues with increased expression of LDL receptors. The selective uptake of the emulsion by the cellular LDL receptors was further confirmed by testing the cellular viability in the presence of competing LDL. The viable cells can reach 92% of control at IC(50) in Caco-2 and 77% in HepG2 incubated with emulsion in the presence of LDL.

Algorithms↗
PubMed2005

Evaluation of the antioxidant capacity and preventive effects of a topical emulsion and its vehicle control on the skin response to UV exposure.

Supplying topical exogenous antioxidants to the skin may prevent or minimize free radical-induced damaging. This study determines antioxidative capacity of a topical skin care emulsion (an oil-in-water vitamin E-containing formulation) versus its vehicle on human skin that was exposed to ultraviolet radiation (UVR) by utilizing a photochemiluminescence device and biophysical methods. Ten healthy Caucasians (3 male and 7 female; mean age 47 +/- 10 years) were enrolled. In a randomized and double-blind manner, a pH-balanced vitamin E emulsion or its vehicle control was applied onto predesignated forearm prior to UVR exposure. Thirty minutes after application, these test sites were exposed to a UV light to induce the minimal erythema dose. One untreated site served as a blank control. Visual scoring and instrumental measurements were recorded at baseline and at 24 h and 48 h thereafter. At day 3, after completing instrumental measurements, each test site was stripped three times in a consecutive manner with a proprietary adhesive tape disc. These tapes were quantified for antioxidant capacity using a photochemiluminescence device. Vitamin E emulsion and vehicle control significantly (p < 0.05) suppressed visual scores when compared with blank control at day 2 and day 3 after UV exposure. However, vitamin E emulsion showed significantly (p < 0.05) lower visual scores when compared with vehicle control at day 2 and day 3 after UV exposure.Also,vitamin E emulsion and its vehicle control significantly (p < 0.05) diminished skin color measurement (a*) values when compared with blank control at day 2 and day 3 after UV exposure. At day 2 after UV exposure, only vitamin E emulsion significantly (p < 0.05) reduced skin blood flow volume when compared with blank control. Vitamin E emulsion and its vehicle control showed significant (p < 0.05) reduction of blood flow volume when compared with blank control at day 3 after UV exposure. Vitamin E emulsion and its vehicle control proved effective in preventing induction of erythema and reducing inflammatory damage caused by UV exposure. The effect of vitamin E emulsion exceeded that of an 'active control'.

Adult↗
PubMedDate not supplied

Effects of administration of different intravenous lipid emulsions on plasma LP-X concentrations in the rat.

BACKGROUND: Prolonged parenteral nutrition with lipid emulsions is essential to provide sufficient energy supply and to avoid essential fatty acid deficiency in preterm infants. However, chronic administration of lipid emulsions may lead to the development of pathological plasma lipid and LP-X concentrations. The aim of this study was to evaluate the relative importance of the phospholipid-triglyceride (PL-TG) ratio and the source of phospholipid in lipid emulsions, with respect to plasma lipid and LP-X levels. METHODS: Rats were infused for 9 days with IV lipid emulsion containing 10% (IL-10) or 20% (IL-20) egg lecithin or Lipofundin containing 20% soya lecithin (LF), with PL-TG ratios of .12, .06, and 0.75, respectively. RESULTS: LF significantly increased plasma triglyceride concentration (p < .01), whereas the rise in cholesterol levels observed with all emulsions was primarily caused by the increase in low-density lipoprotein cholesterol concentrations. The plasma phospholipid concentration was increased most by IL-10 (p < .005). There was a strong correlation between the PL-TG ratio of emulsions and the developing plasma phospholipid and LP-X concentrations (r2 = .91 and .96, respectively), despite the different origin of phospholipids in the emulsions, suggesting that it is the PL-TG ratio, rather than the source of phospholipids in lipid emulsions that primarily influences developing plasma lipid and LP-X concentrations. CONCLUSION: These results indicate that the administration of lipid emulsions with lower PL-TG ratios should be considered, to avoid the development of pathological plasma lipoprotein concentrations.

Analysis of Variance↗
PubMed1995

Absorption of insulin using water-in-oil-in-water emulsion from an enteral loop in rats.

The present work was undertaken to prepare water-in-oil-in-water (W/O/W) emulsions as a carrier for insulin via the enteral route. The emulsions were prepared by a two-step procedure using a homogenizer. To avoid insulin escape from the inner aqueous phase, 3, 5, or 10% gelatin was added in the inner phase. The oily phase was composed of 5% lecithin, 20% Span 80 and 75% soybean oil. The purified water containing 3% Tween 80 was used for the outer aqueous phase. In addition, these emulsions were filtered with a membrane filter (0.45 micron) to obtain smaller emulsion particles. The stability of the emulsions was evaluated by a turbidity measurement method and photomicrographic observation. By the addition of gelatin to the inner aqueous phase and storage at 4 degrees C, the stability of the emulsions could be improved. The hypoglycemic effects of insulin after administration of emulsion to the stomach, the duodenum, the jejunum, the ileum and the colon were examined using an in situ loop method in rats. A significant hypoglycemic effect was observed at the ileum and colon loops after administration of the filtered emulsions containing 5% gelatin in the inner phase. These findings suggest that the W/O/W multiple emulsions stabilized by gelatin can improve ileal and colonic absorption of insulin.

Animals↗
PubMed1999

Biodistribution of gadolinium incorporated in lipid emulsions intraperitoneally administered for neutron-capture therapy with tumor-bearing hamsters.

Emulsions containing a distearylamide (Gd-DTPA-SA) or a distearylester (Gd-DTPA-SE) of Gd (gadolinium)-diethylenetriaminepentaacetic acid (Gd-DTPA) were intraperitoneally injected in Greene's melanoma-bearing hamsters at a dose of 2.0 ml (3.0 or 6.0 mg Gd) per hamster. In the standard-Gd and high-Gd formulations used, the weight ratios of soybean oil, water, Gd-DTPA derivative (Gd-DTPA-SA or Gd-DTPA-SE), hydrogenated L-alpha-phosphatidylcholine from egg yolk (HEPC) and co-surfactant (HCO-60, Myrj 53, Myrj 59 or Brij 700) were 7.36:92:1:2:3 and 7.36:92:2:1:3, respectively. When the effects of the co-surfactants on the biodistribution of Gd from Gd-DTPA-SA-containing emulsions in the standard-Gd formulation were compared, the HCO-60 emulsion exhibited the highest Gd accumulation in tumors, possibly resulting from its fast and complete absorption, its small particle size (78 nm) and the stable coat on the particle surfaces with polyoxyethylene. Brij 700 emulsion kept the highest blood Gd concentration for a prolonged period, possibly due to particle properties similar to those of HCO-60. However, it exhibited a slower Gd accumulation in tumors, only reaching an identical level, in comparison with the HCO-60 emulsion. This suggested the tumor to be saturated with lipid particles. When Gd-DTPA-SE was used instead of Gd-DTPA-SA, its HCO-60 emulsion exhibited only very poor Gd-accumulation due to its easy degradation. The HCO-60 emulsion particles containing Gd-DTPA-SA in the high-Gd formulation (6.0 mg Gd in 2 ml) exhibited in vivo behavior identical to those in the standard-Gd formulation; then the Gd level in tumors reached 107 micrograms Gd/g tumor (wet), and the tumor:blood (T/B) and tumor:skin (T/Sk) Gd concentration ratios were 13.2 and 5.6, respectively, at 48 h after intraperitoneal administration. These results suggest that when intraperitoneally administered, this HCO-60 emulsion, and possibly also the corresponding Brij 700 emulsion, may be an excellent delivery system for accumulating Gd in tumors in neutron-capture therapy (NCT).

Animals↗
PubMed1991

Hepatic uptake of lipid-soluble drugs from fat emulsion.

Oil violet in a fat emulsion was taken up into the parenchymal cells of rat liver in vitro. The uptake was greater at 37 degrees C than 25 degrees C or 4 degrees C, and it was increased by addition of postheparin plasma including lipoprotein lipase activity into the reaction medium. The uptake from the emulsion with smaller particles was greater than that from the emulsion with larger particles. The hepatic uptake of 14C-cholesteryl oleate in the emulsion by recirculating perfusion of the liver in situ was also increased by postheparin plasma in the perfusion medium. Its enhancing effect was found for distribution in the parenchymal cells but not in the Kupffer cells. The previous perfusion of Intralipos of the commercial fat emulsion reduced the hepatic uptake of 14C-cholesteryl oleate in the emulsion. The emulsion particle sizes were reduced by postheparin plasma both in vitro and in situ. Consequently, it was suggested that a lipid-soluble compound entrapped in the fat emulsion is taken up into the parenchymal cells by receptor-mediated process via the reduced particle sizes emulsion (remnant), which is a mechanism similar to the dietary fat metabolism.

Animals↗
PubMed1993

Effect of high concentration perflubron 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 (1) stimulated ex-vivo porcine platelet aggregation pre and post infusion of either perflubron or control (vehicle only) emulsions and (2) stimulated in vitro human platelet calcium flux in the presence of perflubron emulsion or control emulsions. Platelet aggregation stimulated by collagen, ADP or arachadonic 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 inconsistant 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)

Adenosine Diphosphate↗
PubMed1994

The elimination peculiarities of perfluorocarbon emulsions stabilized with egg yolk phospholipid.

In order to examine the elimination rate of Perfluorodecalin (FDC) emulsions stabilized with different emulsifiers--yolk phospholipid (EYP) and procsanol P-268 (analog of Pluronic F-68)--we performed controlled trials on excretion of FDC in exhaled air, elimination from blood and accumulation in the liver. Adult Wistar rats were injected intravenously with FDC emulsions stabilized with different emulsifiers at a dose of 11.5 g FDC per kg body weight. The concentration of FDC in blood, exhaled air and liver tissue was examined by means of the gas chromatography method. The circulation time in blood for the emulsion stabilized with EYP was much longer comparatively to the emulsion containing the synthetic emulsifier procsanol P-268. The injection of EYP dispersions prolonged the circulation time of lipid-stabilised FDC emulsions. The rate of PFC elimination in exhaled air from such an emulsion and the rate of its accumulation in liver during the initial period after injection are reduced compared to the procsanol-stabilized emulsion. These data are interpreted as the result of a reduction of phagocytic activity of blood monocytes toward the lipid-coated particles of the emulsion. The circulation time of PFC emulsion can be prolonged by using lipid emulsifier and additional injections of EYP dispersion.

Animals↗
PubMed1996

Interfacial properties as stability predictors of lecithin-stabilized perfluorocarbon emulsions.

The purpose of this study was to determine whether the addition of small quantities of minor lecithin components (phosphatidylinositol, phosphatidic acid, lysophosphatidylethanolamine, and cholesterol) and Pluronic F68 to lecithin could improve the stability of lecithin-stabilized perfluorocarbon emulsions. Attempts were made to correlate emulsion stability with interfacial properties (tension and charge). Dynamic interfacial tension was determined using a Teflon Wilhelmy plate method [reported previously (1)]. Emulsions were prepared by microfluidization. Microelectrophoresis was used to measure emulsion droplet charge, and photon correlation spectroscopy and Coulter analysis were used to determine emulsion stability as a function of droplet size. Thermal kinetic accelerated stability testing was conducted. Various droplet size parameters were used to compare emulsion stabilities, and an overall stability ranking, based on these parameters, was obtained for each emulsion. Small quantities of additives altered emulsion stability and these data were correlated with interfacial properties and initial droplet diameters. The addition of cholesterol to lecithin resulted in the most stable perfluorocarbon emulsion.

Chemical Phenomena↗
PubMedDate not supplied

A folate receptor-targeted emulsion formulation for paclitaxel.

PURPOSE: This study was aimed at the formulation and an in vitro evaluation of folate receptor (FR)-targeted emulsions as carriers for the lipophilic drug paclitaxel, in FR-overexpressing tumor cells. MATERIALS AND METHODS: FR-targeted paclitaxel emulsions (< 100 nm) composed of Tween-80:triolein:cholesterol:oleic acid:egg-phosphatidylcholine (EPC) (10:30:19.5:30:10), with 0.5 mole % of folate-polyethyleneglycol-cholesterol or polyethyleneglycol-distearoylphosphatidylethanolamine (PEG-DSPE), were prepared by ethanol injection method. Stability of the emulsions was monitored by changes in particle size while at 4 degrees C and 25 degrees C, and drug retention at various time-points. IC50 of the FR-targeted formulations was determined in vitro in the FR+ KB cells. RESULTS: Stable targeted emulsions were prepared by ethanol injection encapsulating greater than 70 percent of paclitaxel, having a mean diameter < 100 nm. In vitro cytotoxicity assay on the FR-targeted emulsions gave IC50 of 0.13 microM in KB cells. There was a significant difference in the IC50 values between the targeted emulsions and those that were non-targeted. CONCLUSION: FR-targeted emulsions incorporating the lipophilic drug paclitaxel were capable of specific receptor binding in cultured KB cells and warrant further investigation in vivo. This article is the first report on an FR-targeted emulsion-type drug carrier. Furthermore, a novel mechanism for in vivo antitumor activity of nanoparticular formulations, such as these emulsions, that is based on their antiangiogenic effect is proposed.

Antineoplastic Agents, Phytogenic↗
PubMedDate not supplied

[Comparative study of two lipid emulsions in patients receiving total parenteral nutrition].

INTRODUCTION: the use of lipid emulsions together with glucose as a calorie source in parenteral nutrition has undisputed advantages. Their isotony and high calorie content mean they are essential for peripheric parenteral nutrition and in parenteral nutrition of long duration they are important in providing essential fatty acids. OBJECTIVE: to determine the constant of elimination of two commercial lipid emulsions with similar compositions, and evaluate whether significant differences exist between them. MATERIAL, METHODS AND PATIENTS: 20 candidates for total parenteral nutrition were studied over a period of at least ten days. These patients showed no severe stress, sepsis or IRA. The patients received total parenteral nutrition for at least 3 days prior to commencing the study; 12 hours after initiation, total parenteral nutrition was administered, without lipids. Afterwards, one of the emulsions studied was infused centrally (in Y with the parenteral nutrition) at a rate of 0.15 g/kg/hour for 3 hours, 24 hours later, the other emulsion was infused under the same conditions. Commencing with one or the other was done at random, and both at 10%. Blood samples were taken at the following times:--10.0 (end of the infusion of the emulsion), 10, 30, 60 and 90 minutes, and the following parameters studied: total cholesterol (col), triglycerides (tg) and phospholipids (pl); tg, col ad pl of the VLDL, HDL and LDL, free fatty acids and lipoprotein lipase. The analytical methods employed were: ultracentrifugation with compressed air and precipitation with PEG-6000. RESULTS: significant differences were observed in the constant of elimination of total tg (2.54 +/- 0.73 in emulsion A compared to 2.8 +/- 0.66 in B), in the Kd of the VLDL tg (1.65 +/- 0.86 in A compared to 1.99 +/- 0.77 in B) and in the Kd of the VLDL P1 (0.98 +/- 0.53 in the case of A compared to 1.1 +/- 0.43 in emulsion B), no significant differences were found in the other parameters studied. The Student T was applied, and no lipase lipoprotein activity was observed. DISCUSSION: the differences found may perhaps be explained by the action of the emulgent on the intravascular metabolism of the fats. Although in both cases this is egg lecithin, the composition of this has not been studied in depth. Emulsion A = Intralipid (n. reg). Emulsion B = Tutolipid (n. reg.).

Analysis of Variance↗
PubMed1981

Studies with a safflower oil emulsion in total parenteral nutrition.

The prevention of essential fatty acid deficiency and the provision of adequate amounts of energy are two major concerns in total parenteral nutrition. Since earlier preparations of fat emulsion used to supplement the usual regimen of hypertonic glucose and amino acids have widely varying clinical acceptability, a new product, a safflower oil emulsion available in two concentrations (Liposyn), was evaluated. In four clinical trials the emulsion was used as a supplement to total parenteral nutrition. In five surgical patients 500 ml of the 10% emulsion infused every third day prevented or corrected essential fatty acid deficiency; however, in some cases in infusion every other day may be necessary. In 40 patients in severe catabolic states the emulsion provided 30% to 50% of the energy required daily: 10 patients received the 10% emulsion for 14 to 42 days, 9 patients received each emulsion in turn for 7 days, and 21 patient received the 20% emulsion for 14 to 28 days. All the patients survived and tolerated the lipid well; no adverse clinical effects were attributable to the lipid infusions. Transient mild, apparently clinically insignificant abnormalities in the results of one or more liver function tests and eosinophilia were observed in some patients. Thus, the safflower oil emulsion, at both concentrations, was safe and effective as a source of 30% to 50% of the energy required daily by seriously ill patients.

Adolescent↗
PubMedDate not supplied

Antibody mediated lung targeting of long-circulating emulsions.

Monoclonal antibody 34A, which specifically binds to a surface glycoprotein (thrombomodulin) of the pulmonary endothelial cell surface in mice, has been conjugated to the surface of long-circulating emulsions composed of Castor oil, phosphatidylcholine and polyethylene glycol coupled to distearoylphosphatidyl-ethanolamine. These antibody-containing emulsions were found capable of binding to the lung when injected into mice through the tail vein. The level of lung accumulation of these emulsions depends on the amount of antibodies conjugated to the surface of the emulsions. With an input antibody to lipid ratio of 2:1 (w/w), 30% injected emulsions were found in the lung 30 minutes after administration. Such high level accumulation can be blocked by co-administration of free 34A antibody, indicating that the binding is specific and 34A antibody mediated. Kinetic studies showed that emulsion targeting to the lung was very rapid. Five minutes after tail vein injection, the total amount of emulsion found in the lung was the highest among the time points examined, indicating the completion of lung binding. However, about 50% of the initially bound emulsions remained bound for more than 4 hours. These results indicate that the targeted drug delivery using oil-in-water emulsions could be very useful to enhance the therapeutic efficacy of lipophilic drugs.

Animals↗
PubMed1997

Effects of Asphaltene Aggregation in Model Heptane-Toluene Mixtures on Stability of Water-in-Oil Emulsions

As part of an ongoing investigation into the stability of water-in-crude oil emulsions, model oils have been utilized to further probe the effects of crude solvency as well as specific resin-asphaltene interactions on emulsion stability. These model oils were constructed by dissolving varying amounts of resins and/or asphaltenes in a mixture of heptane and toluene. The resins and asphaltenes used in this study were isolated from four different crude types-Arab Berri (AB), Arab Heavy (AH), Alaska North Slope (ANS), and San Joaquin Valley (SJV)-and characterized in a previous study using heptane precipitation of the asphaltenes followed by an extrographic separation of the resins from silica gel. Asphaltenes dissolved in heptol at concentrations of just 0.5% were shown to generate emulsions which were even more stable than those generated from their respective whole crude oils. Some types of resins (e.g., from AH and SJV) also demonstrated an ability to stabilize emulsions although these resin-stabilized emulsions were considerably less stable than those prepared with asphaltenes. The primary factors governing the stability of these model emulsions were the aromaticity of the crude medium (as controlled by the heptane:toluene ratio), the concentration of asphaltenes, and the availability of solvating resins in the oil (i.e., the resin/asphaltene or R/A ratio). The model emulsions were the most stable when the crude medium was 30-40% toluene and in many cases at small R/A ratios (i.e., R/A </=1). This strongly supports the theory that asphaltenes are the most effective in stabilizing emulsions when they are near the point of incipient precipitation. The types of resins and asphaltenes used to construct these model oils also played a role in determining the resultant emulsion stability which indicates the importance of specific resin-asphaltene interactions. The interfacially active components that stabilized these model systems were the most polar and/or condensed portions of the resin and asphaltene fractions as determined by elemental and neutron activation analyses. All of these results point to the significance of the solubility state of the asphaltenes in determining the emulsifying potential of these crude oils. Copyright 1997 Academic Press. Copyright 1997Academic Press

Journal Article↗
PubMed1999

Roles of Various Bitumen Components in the Stability of Water-in-Diluted-Bitumen Emulsions.

An experimental study was conducted to evaluate the effectiveness of the various components of Athabasca bitumen in stabilizing water-in-diluted-bitumen emulsions. The solvent used to dilute the very viscous bitumen was a mixture of 50:50 by volume of hexane and toluene. The various bitumen components studied were asphaltenes, deasphalted bitumen, and fine solids. It was found that asphaltenes and fine solids were the main stabilizers of the water-in-diluted-bitumen emulsions. Individually, the two components can stabilize water-in-diluted-bitumen emulsions. However, when both are present the capacity of the diluted bitumen to stabilize water emulsions is greatest. Emulsion stabilization tests indicated that whole bitumen had less capacity to stabilize water emulsions than asphaltenes and solids. This would indicate that the presence of the small molecules within the whole bitumen tends to lower the emulsion stability. Deasphalted bitumen acts as a poor emulsion stabilizer. Although deasphalted bitumen led to the least emulsion stabilization capacity, interfacial tension measurements showed that diluted deasphalted bitumen gave a greater decrease in the interfacial tension of water with diluent. Copyright 1999 Academic Press.

Journal Article↗
PubMed2000

Shear Viscosity Behavior of Emulsions of Two Immiscible Liquids.

The viscous behavior of oil-in-water (O/W) emulsions is studied over a broad range of dispersed-phase concentrations (&phi;) using a controlled-stress rheometer. At low-to-moderate values of &phi; (&phi;<0.60), emulsions exhibit Newtonian behavior. The droplet size does not exert any influence on the viscosity of Newtonian emulsions. However, at higher values of &phi;, emulsions exhibit shear-thinning behavior. The viscosity of shear-thinning emulsions is strongly influenced by the droplet size; a significant increase in the viscosity occurs when the droplet size is reduced. With the decrease in droplet size, the degree of shear thinning in concentrated emulsions is also enhanced. The viscosity data of Newtonian emulsions are described reasonably well by the cell model of Yaron and Gal-Or (Rheol. Acta 11, 241 (1972)), which takes into account the effects of the dispersed-phase concentration as well as the viscosity ratio of the dispersed phase to continuous phase. The relative viscosities of non-Newtonian emulsions having different droplet sizes but the same dispersed-phase concentration are scaled with the particle Reynolds number. The high shear viscosities of non-Newtonian emulsions can be predicted fairly well by the cell model of Yaron and Gal-Or (Rheol. Acta 11, 241 (1972)). Copyright 2000 Academic Press.

Journal Article↗
PubMed1996

Fat emulsions based on structured lipids (1,3-specific triglycerides): an investigation of the in vitro interaction with plasma proteins.

Structured lipids (1,3-specific triglycerides) are new chemical entities made by enzymatic transesterification of the fatty acids in the 1,3-positions of the triglyceride. The purpose of this study was to investigate the in vitro interaction of fat emulsions based on either structured lipids or vegetable oils with human plasma proteins employing two-dimensional polyacrylamide gel electrophoresis (2-D PAGE). The structured lipids are triglycerides of the SLS and MLM types, where S is short-chain fatty acids (C4), M is medium-chain fatty acids (C8-10) and L is long-chain fatty acids (C16-18). The vegetable oil-based fat emulsions were the commercially available product, Intralipid, and a soybean oil (LLL) emulsion made de novo identically as the emulsions containing structured lipids. The SLS emulsion was found to adsorb a different protein pattern than the MLM and LLL emulsions. The protein pattern of the SLS emulsion was similar to the protein pattern of Intralipid. These findings might explain the in vivo difference in elimination found in another study, where the emulsion based on structured lipids with short-chain fatty acids in the 1,3-positions was removed more slowly from the general blood circulation compared to emulsions based on lipids with long-chain fatty acids in the 1,3-positions (LLL).

Journal Article↗