Pancreatic lipase/colipase-mediated triacylglycerol hydrolysis is required for cholesterol transport from lipid emulsions to intestinal cells.
(9/1196)
This study tested the hypothesis that dietary cholesterol uptake by intestinal cells is dependent on the structure and composition of the lipid carriers in the extracellular milieu. In in vivo experiments with female C57BL/6 mice, cholesterol absorption from phospholipid/triacylglycerol emulsions was significantly reduced by administration of tetrahydrolipstatin, an inhibitor of pancreatic lipase. This inhibitor had no effect on the absorption of cholesterol from phospholipid vesicles. The importance of pancreatic-lipase-mediated triacylglycerol hydrolysis for cholesterol transport from emulsions to intestinal cells was confirmed by in vitro experiments with rat IEC-6 intestinal cells. Cellular uptake of cholesterol from emulsions with a phospholipid/triacylglycerol molar ratio of <0.3 could be stimulated by pancreatic lipase/colipase hydrolysis of the core neutral lipids. However, pancreatic lipase/colipase was ineffective in hydrolysing triacylglycerols in emulsions with a phospholipid/triacylglycerol molar ratio of >0.3. Phospholipase A2-mediated hydrolysis of the surface phospholipids was necessary prior to triacylglycerol hydrolysis in these phospholipid-rich emulsions and to the stimulation of cholesterol transport from these particles to IEC-6 cells. The data also revealed that minimal triacylglycerol hydrolysis was sufficient to significantly increase cholesterol transport from lipid emulsions to the intestinal cells. Thus the products of triacylglycerol hydrolysis, namely monoacylglycerol and non-esterified fatty acids, are key determinants in mediating cholesterol transport from lipid emulsions to intestinal cells. Taken together, these results support the hypothesis that remodelling of the surface and core components of lipid carriers is necessary prior to absorption of dietary cholesterol from the gastrointestinal tract. (+info)
Size of lipid microdroplets effects results of hepatic arterial chemotherapy with an anticancer agent in water-in-oil-in-water emulsion to hepatocellular carcinoma.
(10/1196)
We have initially prepared a new drug delivery system for hepatocellular carcinoma (HCC). Using sonication and a detergent, iodinated poppy seed oil (IPSO) can be mixed with an aqueous solution of epirubicin to make a water-in-oil emulsion. The water-in-oil emulsion is further passed through a microporous glass membrane and split into saline to make a long-term inseparable water-in-oil-in-water emulsion (W/O/W) that consists of IPSO microdroplets. To investigate the effect of the size of IPSO microdroplets on the efficacy of injection chemotherapy with W/O/W in patients with HCC, 32 HCC patients were randomly assigned and treated with W/O/W of small IPSO microdroplets (30 micrometers in diameter) containing 60 mg of epirubicin (n = 16, group A) or W/O/W of large IPSO microdroplets (70 micrometers) containing the same amounts of epirubicin (n = 16, group B). Effects were assessed by measuring the percentage of decline of the alpha-fetoprotein (AFP) level in a week from the AFP level immediately before the treatment. The decline was significantly larger in group B (50.5 +/- 19.8, mean +/- S.D.) compared with group A (18.9 +/- 33.1; p <.005). The size of IPSO microdroplets injected into the hepatic artery determines the decrease of serum AFP levels of the patients with HCC. (+info)
Perfluorocarbon emulsion improves oxygenation of the cat primary visual cortex.
(11/1196)
Tissue PO2 was measured in the primary visual cortex of anesthetized, artificially ventilated, normovolemic cats to evaluate the effect of small doses [1 g perfluorocarbon (PFC)/kg] of a PFC emulsion (1 g PFC/1.1 ml emulsion; Alliance Pharmaceutical, San Diego, CA) on brain oxygenation. The change in tissue PO2 (DeltaPO2), resulting from briefly changing the respiratory gas from room air to 100% oxygen, was measured before and after intravenous infusion of the emulsion. Before emulsion, DeltaPO2 was 51.1 +/- 45.6 Torr (n = 8 cats). Increases in DeltaPO2 of 34.0 +/- 26.1 (SD) % (n = 8) and 16. 3 +/- 8.4% (n = 6) were observed after the first and second emulsion infusions, respectively. The further increase in DeltaPO2 after the third dose (7.9 +/- 10.5%; n = 7) was not statistically significant. The observed increases in tissue oxygenation as a result of the PFC infusions appear to be the result of enhanced oxygen transport to the tissue. (+info)
Very low-density lipoprotein activates nuclear factor-kappaB in endothelial cells.
(12/1196)
High plasma levels of VLDL are associated with increased risk for atherosclerosis. Here we show that VLDL (75 to 150 microg/mL) activates nuclear factor-kappaB (NF-kappaB), a transcription factor known to play a key role in regulation of inflammation. Oxidation of VLDL reduced its capacity to activate NF-kappaB in vitro, whereas free fatty acids such as linoleic and oleic acid activated NF-kappaB to the same extent as did VLDL. Intravenous injection of human VLDL (6 mg protein per kg) into rats resulted in arterial activation of NF-kappaB as assessed by electrophoretic mobility shift assay. Aortic endothelial cells showed positive nuclear staining for the activated RelA (p65) subunit of NF-kappaB at 6 to 24 hours after injection. There was also a parallel expression of the adhesion molecules intercellular adhesion molecule-1 and vascular cell adhesion molecule-1, as well as the cytokine tumor necrosis factor-alpha. Pretreatment of the rats with diet containing 1% of the antioxidant probucol for 8 weeks did not inhibit arterial activation of NF-kappaB in response to injection of VLDL. Moreover, injection of triglycerides (10% Intralipid, 5 mL/kg) activated arterial expression of NF-kappaB to the same extent as VLDL. Our results suggest that VLDL may promote the development of atherosclerotic lesions by activation of the proinflammatory transcription factor NF-kappaB. The effect appears to be mediated by a release of VLDL fatty acids but not to involve VLDL oxidation. (+info)
13C nuclear magnetic resonance study of glycogen resynthesis in muscle after glycogen-depleting exercise in healthy men receiving an infusion of lipid emulsion.
(13/1196)
In healthy individuals, glycogen recovery after a strong depletion is known to be rapid and insulin independent during the initial phase, and subsequently, slow and insulin dependent. Free fatty acids (FFAs) as a putative source of insulin resistance (IR) could thus impair glycogen recovery during the second period. Using in vivo 13C nuclear magnetic resonance (NMR), we studied the effect of long-chain triglyceride emulsion on gastrocnemius glycogen resynthesis during a 3-h recovery period after 90 min of moderate exercise consisting of plantar flexion on overnight-fasted healthy men (n = 8). In separate experiments, each subject was infused with 10% Ivelip (0.015 ml x kg(-1) x min(-1)) or 10% glycerol (0.13 mg x kg(-1) x min(-1)). NMR spectra were acquired before and at the end of the exercise and during the recovery period. Whole-body glucose and lipid oxidation rates (indirect calorimetry), plasma insulin, C-peptide, glucose, lactate, beta-hydroxybutyrate, triglycerides, and FFAs were determined. Glycogen consumption was 47.6 +/- 4.5% (glycerol) and 49.7 +/- 4.8% (Ivelip) of the initial glycogen. An acquired IR in the Ivelip group was significant at the onset of the recovery period by homeostasis model assessment (P = 0.002). Glycogen resynthesis in the glycerol group appeared faster during the 1st h than during the subsequent 2nd h of the postexercise period. The glycogen resynthesis level was significantly lower in the Ivelip group than in the glycerol group during the recovery period (P = 0.04 during the 1st h and P = 0.001 during the next 2 h). During the recovery, plasma lactate and whole-body oxidation rates were similar in the two groups, whereas glycemia was significantly higher in the Ivelip group. A decreased cellular uptake of glucose as a substrate for glycogenosynthesis, rather than a competition between oxidation of carbohydrate and FFA, is discussed. (+info)
Synthesis, characterization and preclinical formulation of a dual-action phenyl phosphate derivative of bromo-methoxy zidovudine (compound WHI-07) with potent anti-HIV and spermicidal activities.
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In a systematic effort to develop a microbicide contraceptive capable of preventing transmission of human immunodeficiency virus (HIV), as well as providing fertility control, we have previously identified novel phenyl phosphate derivatives of zidovudine (ZDV) with 5-halo 6-alkoxy substitutions in the thymine ring and halo substitution in the phenyl moiety respectively. Here, we describe the synthesis, characterization, and successful preclinical formulation of our lead compound, 5-bromo-6-methoxy-3'-azidothymidine-5'-(p-bromophenyl) methoxyalaninyl phosphate (WHI-07), which exhibits potent anti-HIV and sperm immobilizing activities. The anti-HIV activity of WHI-07 was tested by measuring viral p24 antigen production and reverse transcriptase activity as markers of viral replication in HIV-1 infected human peripheral blood mononuclear cells (PBMC). WHI-07 inhibited replication of HIV in a concentration-dependent fashion with nanomolar IC50 values. The effects of WHI-07 on human sperm motion kinematics were analysed by computer-assisted sperm analysis (CASA), and its effects on sperm membrane integrity were examined by confocal laser scanning microscopy (CLSM), and high-resolution low-voltage scanning electron microscopy (HR-LVSEM). WHI-07 caused cessation of sperm motility in a concentration- and time-dependent fashion. The in-vitro cytotoxicities of WHI-07 and nonoxynol-9 (N-9) were compared using normal human ectocervical and endocervical epithelial cells by the MTT cell viability assay. Unlike N-9, WHI-07 had no effect upon sperm plasma and acrosomal membrane integrity. N-9 was cytotoxic to normal human ectocervical and endocervical cells at spermicidal doses, whereas WHI-07 was selectively spermicidal. The in-vivo vaginal absorption and vaginal toxicity of 2% gel-microemulsion of WHI-07 was studied in the rabbit model. The sperm immobilizing activity of WHI-07 was 18-fold more potent than that of N-9. Over a 10 day period, there was no irritation or local toxicity to the vaginal epithelia or systemic absorption of WHI-07. Therefore, as a potent anti-HIV agent with spermicidal activity, and lack of mucosal toxicity, WHI-07 may have the clinical potential to become the active ingredient of a vaginal contraceptive for women who are at high risk for acquiring HIV by heterosexual vaginal transmission. (+info)
Receptors for oxidized low-density lipoprotein on elicited mouse peritoneal macrophages can recognize both the modified lipid moieties and the modified protein moieties: implications with respect to macrophage recognition of apoptotic cells.
(15/1196)
It has been shown previously that the binding of oxidized low-density lipoprotein (OxLDL) to resident mouse peritoneal macrophages can be inhibited (up to 70%) by the apoprotein B (apoB) isolated from OxLDL, suggesting that macrophage recognition of OxLDL is primarily dependent on its modified protein moiety. However, recent experiments have demonstrated that the lipids isolated from OxLDL and reconstituted into a microemulsion can also strongly inhibit uptake of OxLDL (up to 80%). The present studies show that lipid microemulsions prepared from OxLDL bind to thioglycollate-elicited macrophages at 4 degrees C in a saturable fashion and inhibit the binding of intact OxLDL and also of the apoB from OxLDL. Reciprocally, the binding of the OxLDL-lipid microemulsions was strongly inhibited by intact OxLDL. A conjugate of synthetic 1-palmitoyl 2(5-oxovaleroyl) phosphatidylcholine (an oxidation product of 1-palmitoyl 2-arachidonoyl phosphatidylcholine) with serum albumin, shown previously to inhibit macrophage binding of intact OxLDL, also inhibited the binding of both the apoprotein and the lipid microemulsions prepared from OxLDL. Finally, a monoclonal antibody against oxidized phospholipids, one that inhibits binding of intact OxLDL to macrophages, also inhibited the binding of both the resolubilized apoB and the lipid microemulsions prepared from OxLDL. These studies support the conclusions that: (i) at least some of the macrophage receptors for oxidized LDL can recognize both the lipid and the protein moieties; and (ii) oxidized phospholipids, in the lipid phase of the lipoprotein and/or covalently linked to the apoB of OxLDL, likely play a role in that recognition. (+info)
A model for evaluation of the peroral insulin therapy: short-term treatment of alloxan diabetic rats with oral water-in-oil-in-water insulin emulsions.
(16/1196)
Alloxan diabetic rats with fasting blood glucose levels above 300 mg/100 ml were treated with oral administration of water-in-oil-in-water (W/O/W) insulin emulsions at a dose of 50 U/100 g body weight, three times daily for 10 to 14 days. The course of diabetes was followed by determinations of glucose levels in blood and urine. During treatment with oral W/O/W insulin emulsions, daily excretion of urinary glucose decreased by about 30 to 40% (2 to 3 g/day) in all of the five rats studied, and returned to the pre-treatment levels after the treatment being discontinued. During treatment, a significant reduction in fasting blood glucose levels was observed in 4 out of 5 rats, giving the decrease by 18 to 44%. Quantitative estimates suggested that the effectiveness of 50 U/100 g of oral W/O/W insulin emulsions was comparable to that after intramuscular regular insulin at a dose of 0.5 U/100 g. Although oral W/O/W insulin emulsions are still of low efficiency, these results would indicate that diabetes can be controlled by effective oral insulin preparations. (+info)