Blood clearance kinetics and organ delivery of medium-chain triglyceride and fish oil-containing lipid emulsions: Comparing different animal species.

BACKGROUND & AIMS: Medium-chain triglycerides (TG) (MCT) and fish oil (FO) TG are incorporated as the core TG component into intravenous (IV) lipid emulsions for infusion in parenteral nutrition. Bolus injections of IV emulsions, on the other hand, have emerged as a novel therapeutic approach to treat various acute disorders. However, intravascular metabolism and organ delivery of acute IV injection of emulsions containing both MCT and FO are not fully defined, nor have they been characterized across common experimental animal models. We characterized and compared blood clearance kinetics and organ distribution of bolus injections of MCT/FO emulsions among different animal species. We also examined whether sex differences or feeding status can affect catabolic properties of MCT/FO lipid emulsions. DESIGN: Blood clearance rates of lipid emulsions with specific TG composition were compared in rats IV injected with [3H]cholesteryl hexadecyl ether labeled pure n-6 long-chain (LCT) and n-3 FO TG lipid emulsions, or emulsions containing MCT and FO at different ratios (wt/wt), which include 8:2 (80% MCT: 20% FO), 5:4:1 (50% MCT: 40% LCT: 10% FO) and SMOF (30% LCT: 30% MCT: 25% olive oil: 10% FO). Dose-response effects (0.016 mg-1.6 mg TG/g body weight) of the MCT/FO 8:2 emulsions on blood clearance properties and organ delivery were determined in both mice and rats. Blood clearance kinetics and organ uptake of MCT/FO 8:2 emulsions were compared between male and female rats and between fed and fasted rats. Changes in plasma lipid profiles after acute injections of MCT/FO 8:2 lipid emulsion at different doses (0.043, 0.133, and 0.4 mg TG/g body weight) were characterized in non-human primates (Cynomolgus monkeys). RESULTS: MCT/FO 8:2 emulsion was cleared faster in rats when compared with other emulsions with different TG contents. Mice had faster blood clearance and higher fractional catabolic rates (FCR) when compared with the rats injected with MCT/FO 8:2 emulsions regardless of the injected doses. Mice and rats had similar plasma TG and free fatty acid (FFA) levels after low- or high-dose injections of the MCT/FO emulsion. Tissue distribution of the MCT/FO 8:2 lipid emulsion are comparable between mice and rats, where liver had the highest uptake per recovered dose among all organs (>60%). Feeding status and sex differences did not alter the blood clearance rate of the MCT/FO 8:2 emulsion in rats. In a nonhuman primate model, dose-response increases in plasma TG and FFA were observed after IV injection of MCT/FO 8:2 emulsions within the 1st 10 min. CONCLUSION: A lipid emulsion containing both MCT and FO TG is cleared rapidly in blood and readily available for organ uptake in rodent and primate animal models. Characterization of the blood clearance properties of the MCT/FO 8:2 emulsion administered in various animal models may provide further insight into the safety and efficacy profiles for future therapeutic use of bolus injections of MCT/FO emulsions in humans.

Half-life of plasma phytosterols in very low birth weight preterm infants on routine parenteral nutrition with vegetable oil-based lipid emulsions.

BACKGROUND: Phytosterols in vegetable oil (VO)-based lipid emulsions (LE) likely contribute to parenteral nutrition-associated cholestasis (PNAC) in preterm infants. No characterization of plasma phytosterol half-lives has been done in very low birth weight (VLBW) preterm infants receiving parenteral nutrition (PN) with LE. METHODS: In a prospective cohort study, 45 VLBW preterm infants who received PN underwent serial blood sample measurements of sitosterol (SITO), campesterol (CAMP), and stigmasterol (STIGM). Plasma phytosterol half-lives were calculated from the phytosterol concentrations-decay curves by using a single-compartment model. RESULTS: After the stop of the intravenous LE, study infants had significantly lower plasma total CAMP, STIGM and SITO concentrations. The decay of plasma phytosterol concentrations was monoexponential. Half-life of plasma total CAMP, STIGM and SITO was 13.5 ± 6.9, 10.3 ± 4.5 and 10.3 ± 4.0 days, respectively. Plasma phytosterol half-lives did not correlate with gestational age, birth weight, cumulative phytosterol intakes and plasma conjugated bilirubin. CONCLUSION: VLBW preterm infants on PN with LE had rather long plasma phytosterol half-lives similar to hypercholesterolemic adults and phytosterolemic homozygotes patients. We speculate that the accumulation of phytosterols could contribute to their vulnerability to PNAC. CLINICAL TRIAL REGISTRY: The Ethics Committee of Marche-Italy (DG/469); www.clinicaltrials.gov (identification number NCT02758834).

Formulation, Optimization, Characterization, and Pharmacokinetics of Progesterone Intravenous Lipid Emulsion for Traumatic Brain Injury Therapy.

Traumatic brain injury (TBI) is a major cause of mortality and disability throughout the world. Progesterone (PROG) plays an important role in neurologic treatment. The aim of this study was to develop a progesterone formulation with good physical and chemical stability. Progesterone intravenous lipid emulsion (PILE) was prepared based on one-factor-at-a-time experiments and orthogonal design. The optimal PILE was evaluated for mean particle size, particle size distribution, zeta potential, morphology, pH, osmolarity, entrapment efficiency, storage stability, and pharmacokinetics in ICR mice compared with the commercial progesterone products. The droplets of PILE had the smallest possible diameters of 218.0 ± 1.8 nm and adequate zeta potential of -41.1 ± 0.9 mV. The volume percentage of droplets exceeding 5 µm (PFAT5) of PILE was 0.003 ± 0.0015% and much less than the specified standard. The TEM imaging proved that emulsion droplets had a smooth spherical appearance. Chemically and physically stable PILE was obtained with excellent entrapment efficiency that was up to 95.23%, with suitable pH at 7.15 ± 0.01 and osmolarity at 301.3 ± 1.2 mOsmol/l. Storage stability tests indicated that the emulsion was stable long term under ambient temperature conditions. Animal studies demonstrated that the emulsion was more effective with the higher progesterone concentration in the brain compared with commercial products. Therefore, the optimized PILE would offer great promise as a means of progesterone delivery for TBI therapy.

Experimental assessment of temperature influence on miriplatin and cisplatin iodized-oil suspension viscosity.

PURPOSE: To evaluate differences in the viscosity of a platinum iodized-oil suspension on the kind of platinum agent and temperature. MATERIALS AND METHODS: Viscosities of a 70 mg miriplatin and 3.5 ml iodized-oil suspension (MO suspension) and that of 100 mg cisplatin and 10 ml iodized-oil suspension (CO suspension) were evaluated at three temperatures: 25, 37, and 50 °C. Iodized-oil was used as the control. Each liquid was injected into a capillary tube and allowed to drip separately. The liquid transit time was measured, and the viscosity of each liquid was calculated at each temperature. RESULTS: The viscosity of each liquid decreased as the temperature increased: 43.3 ± 0.5, 39.2 ± 0.7, and 34.7 ± 0.6 mPa s for MO suspension, 41.3 ± 0.2, 36.9 ± 0.3, and 32.7 ± 0.9 mPa s for CO suspension, and 40.5 ± 0.2, 36.8 ± 0.2, and 33.8 ± 0.7 mPa s for iodized-oil at 25, 37, and 50 °C, respectively. The MO suspension group viscosity was significantly higher than that of the CO suspension group (p < 0.05) and the control (p < 0.05). Significant differences were found in viscosities among groups divided by temperature (25 °C-group vs. 37 °C-group, p < 0.05; 37 °C-group vs. 50 °C-group, p < 0.05). CONCLUSION: The viscosity of the platinum iodized-oil suspension can be adjusted by changing temperature.

Decreased reticuloendothelial system clearance and increased blood half-life and immune cell labeling for nano- and micron-sized superparamagnetic iron-oxide particles upon pre-treatment with Intralipid.

BACKGROUND: Superparamagnetic iron-oxide nanoparticles are useful as contrast agents for anatomical, functional and cellular MRI, drug delivery agents, and diagnostic biosensors. Nanoparticles are generally cleared by the reticuloendothelial system (RES), in particular taken up by Kupffer cells in the liver, limiting particle bioavailability and in-vivo applications. Strategies that decrease the RES clearance and prolong the circulation residence time of particles can improve the in-vivo targeting efficiency. METHODS: Intralipid 20.0%, an FDA approved nutritional supplement, was intravenously administered in rats at the clinical dose (2g/kg) 1h before intravenous injection of ultra-small superparamagnetic iron-oxide (USPIO) or micron-sized paramagnetic iron-oxide (MPIO) particles. Blood half-life, monocyte labeling efficiency, and particle biodistribution were assessed by magnetic resonance relaxometry, flow cytometry, inductively-coupled plasma MS, and histology. RESULTS: Pre-treatment with Intralipid resulted in a 3.1-fold increase in USPIO blood half-life and a 2-fold increase in USPIO-labeled monocytes. A 2.5-fold increase in MPIO blood half-life and a 5-fold increase in MPIO-labeled monocytes were observed following Intralipid pre-treatment, with a 3.2-fold increase in mean iron content up to 2.60pg Fe/monocyte. With Intralipid, there was a 49.2% and 45.1% reduction in liver uptake vs. untreated controls at 48h for USPIO and MPIO, respectively. CONCLUSIONS: Intralipid pre-treatment significantly decreases initial RES uptake and increases in-vivo circulation and blood monocyte labeling efficiency for nano- and micron-sized superparamagnetic iron-oxide particles. GENERAL SIGNIFICANCE: Our findings can have broad applications for imaging and drug delivery applications, increasing the bioavailability of nano- and micron-sized particles for target sites other than the liver.

Soybean oil: a potentially new intravascular perfusate.

BACKGROUND: Given that micelles of lipids are colloids, the hypothesis was generated that the rapid administration of large volumes of soybean oil micelles would be an effective perfusion fluid. We also hypothesized that oxygen loading would be enhanced due to the greater solubility of oxygen in lipids compared to water. METHODS: A 100% lethal mouse model of blood loss was used to compare the ability of soybean oil micelles to that of Ringer's lactate, blood and other fluids, with respect to raising and maintaining the blood pressure for one hour. Oxygen on- and off-loading of various concentrations of soybean oil micelles was determined using mass spectroscopy. Nitric oxide uptake by micelles was also determined in a similar fashion. RESULTS: A 20% soybean oil emulsion was superior to Ringer's lactate in raising and maintaining blood pressure. A 20% soybean oil emulsion with 5% albumin added was superior to shed blood as well as solutions comprised of 5% albumin added to either normal saline or Ringer's lactate. There was a linear relationship between oxygen content and micelle concentration between 10% and 30%. Off-loading of oxygen from the micelles was nearly as fast as off-loading from water. Nitric oxide also loaded preferentially onto soybean oil micelles. CONCLUSIONS: (1) Soybean oil emulsions were superior to other fluids in restoring and maintaining the blood pressure; (2) oxygen-carrying ability of soybean oil micelles exceeds that of water and follows Henry's law between 10% and 30% w/v oil content; (3) nitric oxide was carried by the micelles; (4) animals receiving soybean oil micelles did not exhibit fat embolization; (5) colloids comprised of soybean oil-containing micelles may be used to replace blood loss and may be used to deliver oxygen and other potentially therapeutic gases such as nitric oxide to tissues.

Pharmacokinetic evaluation of pancreatic arterial infusion chemotherapy with lipid emulsion as a drug carrier in an animal model.

The purpose of this study was to investigate the potential pharmacokinetic advantage of pancreatic arterial infusion chemotherapy with lipid emulsion as a drug carrier for pancreatic cancer in a dog model. The 20% Intralipid, as a solvent, was used in the experimental animals with 2 ml/kg (group A) and 1 ml/kg (group B). Normal sodium as a solvent was used as a control with 2 ml/kg (group C) and 1 ml/kg (group D), respectively. Cisplatin (4 mg/kg) was infused into the proximal segment of the splenic artery. The concentrations of cisplatin were measured in plasma of the portal vein and in the liver and pancreas of groups A and C. The area under the concentration-time curve (AUC), the maximum plasma concentration (C(max)), and the elimination half-life (t(1/2)) in plasma were calculated and compared statistically. Compared with group C, the AUC and C(max) of group A were significantly lower (P<0.01 and P<0.01, respectively), the t 1/2 was longer (P<0.05), and the tissue cisplatin concentration of the pancreas was higher (P<0.05). Compared with group D, the AUC and C(max) of group B were significantly lower (P<0.01 and P<0.01, respectively) and the t(1/2) was longer (P<0.01). Pancreatic arterial infusion chemotherapy with lipid emulsion as a drug carrier can increase the local concentration and prolong the retention time of a drug.

Metabolism of a lipid nanoemulsion resembling low-density lipoprotein in patients with grade III obesity

Introduction: Obesity increases triglyceride levels and decreases high-density lipoprotein concentrations in plasma. Artificial emulsions resembling lipidic plasma lipoprotein structures have been used to evaluate low-density lipoprotein metabolism. In grade III obesity, low density lipoprotein metabolism is poorly understood. Objective: To evaluate the kinetics with which a cholesterol-rich emulsion (called a low-density emulsion) binds to low-density lipoprotein receptors in a group of patients with grade III obesity by the fractional clearance rate. Methods: A low-density emulsion was labeled with [14C]-cholesterol ester and [³H]-triglycerides and injected intravenously into ten normolipidemic non-diabetic patients with grade III obesity [body mass index higher than 40 kg/m²] and into ten non-obese healthy controls. Blood samples were collected over 24 hours to determine the plasma decay curve and to calculate the fractional clearance rate. Results: There was no difference regarding plasma levels of total cholesterol or low-density lipoprotein cholesterol between the two groups. The fractional clearance rate of triglycerides was 0.086 ± 0.044 in the obese group and 0.122 ± 0.026 in the controls (p = 0.040), and the fractional clearance rate of cholesterol ester (h-1) was 0.052 ± 0.021 in the obese subjects and 0.058 ± 0.015 (p = 0.971) in the controls. Conclusion: Grade III obese subjects exhibited normal low-density lipoprotein removal from plasma as tested by the nanoemulsion method, but triglyceride removal was slower.

Effect of a cholesterol-rich diet on the metabolism of the free and esterified cholesterol components of a nanoemulsion that resembles LDL in rabbits

We have shown that the free cholesterol (FC) and the cholesteryl ester (CE) moieties of a nanoemulsion with lipidic structure resembling low-density lipoproteins show distinct metabolic fate in subjects and that this may be related to the presence of dyslipidemia and atherosclerosis. The question was raised whether induction of hyperlipidemia and atherosclerosis in rabbits would affect the metabolic behavior of the two cholesterol forms. Male New Zealand rabbits aged 4-5 months were allocated to a control group (N = 17) fed regular chow and to a 1 percent cholesterol-fed group (N = 13) during a 2-month period. Subsequently, the nanoemulsion labeled with ³H-FC and 14C-CE was injected intravenously for the determination of plasma kinetics and tissue uptake of the radioactive labels. In controls, FC and CE had similar plasma kinetics (fractional clearance rate, FCR = 0.234 ± 0.056 and 0.170 ± 0.038 h-1, respectively; P = 0.065). In cholesterol-fed rabbits, the clearance of both labels was delayed and, as a remarkable feature, FC-FCR (0.089 ± 0.033 h-1) was considerably greater than CE-FCR (0.046 ± 0.010 h-1; P = 0.026). In the liver, the major nanoemulsion uptake site, uptake of the labels was similar in control animals (FC = 0.2256 ± 0.1475 and CE = 0.2135 ± 0.1580 percent/g) but in cholesterol-fed animals FC uptake (0.0890 ± 0.0319 percent/g) was greater than CE uptake (0.0595 ± 0.0207 percent/g; P < 0.05). Therefore, whereas in controls, FC and CE have similar metabolism, the induction of dyslipidemia and atherosclerosis resulted in dissociation of the two forms of cholesterol.

Triglycerides in fish oil affect the blood clearance of lipid emulsions containing long- and medium-chain triglycerides in mice.

Lipid emulsions containing long-chain triglycerides (LCT) and medium chain triglycerides (MCT) are widely used in parenteral nutrition. Recently, fish oil (FO) triglyceride (TG)-derived emulsions are considered therapeutic because of their many beneficial biological modulatory actions. We investigated in mice whether adding 10% FO to an intravenous lipid emulsion with MCT and LCT (MCT:LCT:FO -50:40:10% by wt) would affect particle blood clearance and tissue targeting in comparison to LCT (100% by wt) and MCT:LCT (50:50% by wt) emulsions. The 3 emulsions were labeled with [3H] cholesteryl oleoyl ether and administered by bolus injection (400 microg TG/mouse) to C57BL/6J mice. Contributions of LDL receptor (LDL-R) and LDL-R-related protein to emulsion catabolism were assessed using LDL-R-deficient mice and preinjection of lactoferrin, and the effects of lipoprotein lipase (LPL) were determined by preinjection of heparin and Triton WR 1339. Although fractional catabolic rates did not differ among the 3 emulsions, blood removal at each time point after injection was greater for MCT:LCT:FO particles due to their higher initial margination volume. Compared with MCT:LCT and LCT emulsions, patterns of tissue uptake of the MCT:LCT:FO emulsions were different, e.g. MCT:LCT:FO emulsion particle uptake was lower in heart, adipose tissue, and muscle, and higher in lung, and the removal of MCT:LCT:FO emulsion particles was less dependent on LPL, LDL-R, and lactoferrin-sensitive pathways. These data suggest that the addition of a low percentage of FO to MCT:LCT emulsions substantially changes their particle clearance and tissue uptake mechanisms.

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.

In vivo and in vitro properties of an intravenous lipid emulsion containing only medium chain and fish oil triglycerides.

BACKGROUND & AIMS: The triglyceride (TG) fatty acyl composition in lipid emulsions influences their metabolism. Little is known about the effects of long chain omega-3 polyunsaturated fatty acids (PUFA) on lipid emulsion metabolism. We investigated possible differences between omega-3 containing emulsions in their metabolism and tissue-targeting in vivo in a mouse model, and in vitro using lipolysis and cell culture experiments. METHODS: Soy oil (LCT), MCT/LCT/omega-3 (5:4:1, wt/wt/wt), and MCT/omega-3 (8:2, wt/wt) emulsions were radiolabeled with nondegradable 1alpha,2alpha (n)-[3H] cholesteryl oleoyl ether to trace core particle metabolism in C57BL/6J mice following a bolus injection. Blood samples obtained over 25 min and extracted organs were used to measure the tissue distribution of lipid emulsion particles. Lipoprotein lipase (LpL)-mediated hydrolysis experiments and cell uptake studies in cultured J774 murine macrophages were also performed. RESULTS: Blood clearance of 8:2 was 13.4% and 29.8% faster compared to 5:4:1 and LCT, respectively. LCT had greatest liver uptake. LpL-mediated hydrolysis was greatest in 8:2 and lowest in LCT. Overall, cell TG accumulation in the presence of apolipoprotein E was least with 8:2. CONCLUSIONS: Our data shows that 8:2 had the most efficient blood clearance but less hepatic uptake in vivo. In vitro, 8:2 had both highest hydrolysis by LpL and intracellular TG utilization in the presence of apoE. Thus, an 8:2 lipid emulsion undergoes efficient blood clearance and may direct omega-3 PUFA more towards extrahepatic tissues.

Isoflurano em emulsão lipídica por via venosa promove estabilidade cardiovascular respiratória em modelo experimental / Intravenous isoflurane in lipid emulsion promotes cardiovascular and respiratory stability. Experimental model

JUSTIFICATIVA E OBJETIVOS: A administração venosa de anestésico inalatório pode causar lesão pulmonar. Halotano em solução lipídica por via venosa promove anestesia com estabilidade hemodinâmica e respiratória. Esta pesquisa procurou estabelecer a dose de indução para emulsão lipídica de isoflurano a 10 por cento e observar as condições cardiovasculares e respiratórias, em anestesia experimental. MÉTODO: Sete porcos machos foram selecionados. Os animais receberam infusão de propofol para as preparações cirúrgicas invasivas: dissecção de artéria femoral e veia jugular, sensor de ecodopplercardiografia no esôfago. Foram registrados freqüência cardíaca (FC), eletrocardiograma (ECG), pressão arterial sistólica (PAS), diastólica (PAD), média (PAM), venosa central (PVC), índice cardíaco (IC), débito cardíaco (DC) e índice bispectral (BIS). As frações inspirada e expirada dos gases respiratórios foram analisadas continuamente. Iniciada infusão da emulsão lipídica de isoflurano até o índice bispectral atingir valor de 40 ± 5 (BIS40). Os animais foram mantidos anestesiados e submetidos a laparotomia exploradora para sutura gástrica. RESULTADOS: O volume total infundido para atingir BIS40 foi 25,6 ± 11,2 ml (2,56 ml de isoflurano). O tempo médio para atingir BIS40 foi 15,6 ± 6,9 minutos. Maior velocidade de infusão reduziu o tempo para os animais atingirem BIS40. Condições cardiovasculares e respiratórias mostraram-se estáveis durante a experimentação. A freqüência cardíaca aumentou com a elevação da fração expirada do isoflurano. CONCLUSÕES: A infusão venosa do isoflurano em solução emulsificada promoveu diminuição do índice bispectral, estabilidades hemodinâmica e respiratória e correlação direta com sua fração expirada. O uso do isoflurano em emulsão lipídica pode se constituir em modalidade segura de aplicação deste anestésico.

Cationic lipid emulsions containing heavy oils for the transfection of adherent cells.

A new cationic emulsion system with high density was prepared increasing in vitro transfection efficiencies of adherent cells. Lipiodol with a density of 1.3 (g/ml) was selected to increase the density of the DNA/emulsion complex. Cationic lipid emulsions were formulated with mixtures of lipiodol and squalene as the oil phase and 1,2-dioleoyl-sn-glycero-3-trimethylammonium-propane (DOTAP) as a cationic lipid. These emulsions were used to find the correlation between the density and the in vitro transfection efficiency. The physical characteristics of the new emulsion formulations were also determined. Heavier DNA/cationic lipid emulsion complex showed higher in vitro transfection efficiency on adherent cell lines in the presence of 10% serum compared to lighter ones. The cationic lipid emulsion formulated with lipiodol and DOTAP was more stable and showed better in vitro transfection efficiency than other carriers without lipiodol. Due to the high density of the carrier, the DNA/carrier complex sank to the bottom of the wells, thereby increasing the contact between the complex and adherent cells. The new lipiodol emulsion with high density showed superior transfection activities on adherent cells in the presence of serum.

Removal of intravenous Intralipid in patients with familial hypercholesterolemia during inhibition of cholesterol absorption and synthesis.

BACKGROUND: While plant stanols are known to upregulate low density lipoprotein (LDL) receptors, we studied the effects of plant stanol (STA) and sterol (STE) ester spreads on triglyceride-rich lipoprotein (TRL) removal in statin-treated patients with familial hypercholesterolemia (FH) using intravenous Intralipid-squalene fat tolerance test. METHODS: Five patients consumed STA and STE in a randomized, crossover study for 4 weeks. TRL removal was studied at baseline and at the end of both periods. Serum, chylomicron (CM), and very low density lipoprotein lipids, squalene, and plant sterols were measured. RESULTS: LDL cholesterol was decreased by both spreads (15-16%, p<0.05). Plant sterol concentrations were doubled in serum and CM by STE vs. STA. After the injection of Intralipid, CM squalene and sitosterol, but not triglycerides (TG), reached higher peak levels (and area under the incremental curve (AUIC) of squalene) by both spreads than at baseline. Despite different plant sterol concentrations by STE vs. STA, the incremental curves for plant sterols were similar by the spreads. CONCLUSIONS: Despite the retarded removal of TRL lipids by STA and STE in the statin-treated subjects with FH, improvement of the fasting lipid profile was suggested important in consideration of combination of cholesterol absorption inhibitor with statins even in FH.

Abnormal regulation of serum lipid fatty acid profiles in short gut rats fed parenteral nutrition with lipid.

Despite absence of essential fatty acid deficiency (EFAD), increases in arachidonic acid to linoleic acid ratios occur in serum phospholipid of patients treated with chronic total parenteral nutrition (TPN). The parenteral lipid component of TPN contains abundant linoleate; thus low phospholipid linoleate may reflect increased conversion to arachidonate. Arachidonic acid excess has been associated with a proinflammatory milieu through increased eicosanoid production and might contribute to the increases in inflammatory markers seen in home TPN patients. We investigated fatty acid metabolism in a rodent model of malabsorption. We hypothesized that short gut rats would metabolize parenteral lipid differently from intact rats. We performed laparotomy and 80% small bowel resection (or sham surgery) in rats. Sixteen sham and 16 short gut rats were randomly assigned to TPN with lipid or fat-free TPN. After 5 days, weight loss was similar in all groups. Analysis of serum phospholipids demonstrated that 20:3omega9 (eicosatrienoic acid) was relatively increased in fat-free TPN groups, irrespective of surgery type, as were distal very long chain omega3 class fatty acids, as anticipated. Uniquely, both nutrition (TPN/lipid v fat-free TPN) and surgery type (sham v short gut) were significant in determining arachidonic acid levels. Relatively elevated arachidonate occurred in both groups of fat-free rats, suggesting increased Delta6 and/or Delta5 desaturase activity, as expected. In contrast, giving TPN/lipid lowered arachidonate (suggesting appropriately downregulated desaturases) in sham animals, but not in short gut animals. Ratios of arachidonic and di-homo-gamma-linolenic to linoleic acids further suggested increased turnover of precursor omega6 to arachidonic acid in short gut rats given lipid compared with the other groups. These preliminary data show that intravenous (IV) lipid gave rise to serum lipid fatty acid profiles that differed in short gut and sham rats. The short gut rat may have a heightened hepatic desaturase activity, inappropriate for the quantity of linoleic acid provided parenterally. Therefore, the short gut rat is an appropriate model to study further arachidonic acid excess in home TPN patients.

Dissociation between fat-induced in vivo insulin resistance and proximal insulin signaling in skeletal muscle in men at risk for type 2 diabetes.

The effect of short- (2 h) and long-term (24 h) low-grade Intralipid infusion on whole-body insulin action, cellular glucose metabolism, and proximal components of the insulin signal transduction cascade was studied in seven obese male glucose intolerant first degree relatives of type 2 diabetic patients [impaired glucose tolerance (IGT) relatives] and eight matched control subjects. Indirect calorimetry and excision of vastus lateralis skeletal muscle biopsies were performed before and during hyperinsulinemic euglycemic clamps combined with 3[(3)H]glucose. Clamps were performed after 0, 2, or 24 h Intralipid infusion (0.4 ml.kg(-1).min(-1)). Insulin-stimulated glucose disposal decreased approximately 25% after short- and long-term fat infusion in both IGT relatives and controls. Glucose oxidation decreased and lipid oxidation increased after both short- and long-term fat infusion in both groups. Insulin-stimulated glucose oxidation was higher after long-term as compared with short-term fat infusion in control subjects. Short- or long-term infusion did not affect the absolute values of basal or insulin-stimulated insulin receptor substrate-1 tyrosine phosphorylation, tyrosine-associated phosphoinositide 3-kinase (PI 3-kinase) activity, insulin receptor substrate-1-associated PI 3-kinase activity, or Akt serine phosphorylation in IGT relatives or matched controls. In fact, a paradoxical increase in both basal and insulin-stimulated PI 3-kinase activity was noted in the total study population after both short- and long-term fat infusion. Short- and long-term low-grade Intralipid infusion-induced (or enhanced) whole-body insulin resistance and impaired glucose metabolism in IGT relatives and matched control subjects. The fat-induced metabolic changes were not explained by impairment of the proximal insulin signaling transduction in skeletal muscle.

Effect of particle size on the pharmacokinetics of menatetrenone incorporated in O/W lipid emulsions prepared with hydrogenated castor oils and soybean oil in rats.

Previously, we prepared lipid emulsions with soybean oil (SO; 20%) as oil phase and hydrogenated castor oils (HCOs; 2.4%) as emulsifiers (SO(20)/HCOs(2.4)), and found that the lipid emulsions prepared with HCO of 10 oxyethylene units (SO(20)/HCO10(2.4)) were quickly cleared from the plasma, while those prepared with HCO of 20 oxyethylene units (SO(20)/HCO20(2.4)) showed prolonged plasma circulation of the incorporated drug (Ueda et al., 2003). In the present study, the pharmacokinetics of menatetrenone incorporated into SO/HCO10s and SO/HCO20s of different particle sizes (100-280 nm), obtained by altering the SO contents, were examined in rats. The plasma half-lives of menatetrenone as SO/HCO10s were similar to each other, irrespective of particle size, even though the liver uptake of menatetrenone as SO(2.5)/HCO10(2.4) was larger than that as SO(20)/HCO10(2.4). The menatetrenone half-lives were also similar to each other for SO/HCO20s. The pretreatment with dextran sulfate 500,000 (DS500), a suppressor of the reticuloendothelial system (RES), increased the plasma concentration and inhibited the liver uptake of menatetrenone as SO/HCO10s, but not for those as SO/HCO20s. These findings indicated that the particle sizes did not affect the minimum oxyethylene units within HCOs for the prolonged plasma circulation of menatetrenone as SO/HCOs, which was 20.

A lipophilic paclitaxel derivative incorporated in a lipid emulsion for parenteral administration.

Paclitaxel is one of the most effective and most widely-used anti-cancer agents. However, paclitaxel is difficult to formulate for parenteral administration because of its low aqueous solubility and Cremophor EL, the excipient used for its formulation, has been shown to cause serious side effects. This study reports an alternative administration vehicle involving a lipophilic paclitaxel derivative, paclitaxel oleate, incorporated in the core of a nano-size sterically stabilized oil-in-water (o/w) lipid emulsion. This lipid emulsion, with a particle size of 50 nm, has many favourable properties such as drug-carrier like biocompatibility, physical stability and ease of preparation. When paclitaxel in Cremophor EL/ethanol and paclitaxel oleate in emulsion were incubated with plasma a greater proportion of paclitaxel was found in the lipoprotein pool when formulated as paclitaxel oleate in a lipid emulsion compared to unesterified paclitaxel. The paclitaxel prodrug, paclitaxel oleate, demonstrated cytotoxic activity against cultured HeLa cells and with a marked increase in activity with incubation time. The 50% inhibition (IC(50)) was calculated to be 5500, 500, 150, and 100 nM for 24, 48, 72, and 96 h, respectively. Pharmacokinetic data, obtained with rabbits, showed significantly greater AUC, higher C(max), lower systemic clearance and lower V(ss) when paclitaxel was formulated as an oleate prodrug in a lipid emulsion than when formulated in Cremophor EL/ethanol. The formulated emulsion may be clinically useful not only for eliminating toxic effects of Cremophor EL but also for improvement of the pharmacokinetic parameters of paclitaxel.

Effects of oolong tea on metabolism of plasma fat in mice under restraint stress.

We investigated the effects of oolong tea on the basic metabolism of plasma lipids in mice under restraint stress. When a lipid emulsion (Intralipid 20%; a lipid emulsion containing 20% soybean oil) was injected intravenously into mice, the restraint stress prolonged the half-life (T 1/2) of elimination for plasma triglyceride (TG) from 28.7 to 55.5 min. The elimination rate per minute was 48.2% in stressed mice with the rate in starved control mice as 100%. Therefore, TG metabolism was disrupted by the stress, and the use of TG as an energy source decreased. We found that the metabolism of lipids significantly response to the restrained stress in the present study. Plasma TG was 515.9 +/- 29.9mg/dl 35min after Intralipid administration in control stressed mice, 478.7 +/- 26.7 mg/dl in the stressed group given caffeine 100 mg/kg of body weight, and 418.3 +/- 18.4 mg/dl in the stressed group given 1,000 mg/kg oolong tea, an improvement by 7.2% and 18.9%, respectively, with the value for the untreated control group. The intake of oolong tea alleviated the stress-induced decrease in the rate of blood lipid metabolism; this effect may have arisen from some non-specific stress-relieving property of the tea or from acceleration of lipid metabolism by properties of polyphenols, etc. in tea. Oolong tea had anti-stress effects on plasma TG metabolism, and the effects did not depend on caffeine.