Peter J. Gillies

Cross-sectional Study of Lipids and Liver Enzymes Related to a Serum Biomarker of Exposure (ammonium perfluorooctanoate or Apfo) as Part of a General Health Survey in a Cohort of Occupationally Exposed Workers

Objective: To examine the relationship between serum perfluorooctanoate (PFOA), a biomarker of ammonium perfluorooctanoate (APFO) exposure, and lipids and liver enzymes in a cross-sectional study among workers with potential occupational exposure to APFO. Methods: We conducted a cross-sectional study of 1025 active workers with potential exposure to APFO using linear regression to examine the relationship between PFOA and selected outcomes from a standard metabolic health screening survey, emphasizing lipids and liver enzymes. Results: Most outcome parameters were within normal limits. After adjusting for potential confounders, we observed a modest but statistically significant, positive relationship between serum PFOA and total cholesterol, low-density lipoprotein (LDL), very low-density lipoprotein (VLDL), and gamma glutamyl aminotransferase (GGT). No associations were seen for high-density lipoprotein (HDL) or bilirubin; associations with AST (aspartate aminotransferase) and ALT (alanine transpeptidase) did not reach statistical significance. Conclusions: Our findings indicate a modest positive association of PFOA on some lipid parameters and a need for follow-up studies.

Gene expression of acyl-coenzyme-A:cholesterol-acyltransferase is upregulated in human monocytes during differentiation and foam cell formation.

The gene expression and enzyme kinetics of acyl coenzyme A:cholesterol acyltransferase (ACAT) were investigated in human monocytes, macrophages, and foam cells. Northern blot analysis using a 1.65-kb coding region of human ACAT cDNA as the probe showed that each of the cell types exhibited four mRNA transcripts. The levels of the 4.2- and 3.7-kb ACAT transcripts were three- and sixfold higher, respectively, in macrophages than monocytes. These transcripts were expressed at the same high levels after conversion of macrophages to foam cells. In contrast, the 6.3- and 4.4-kb transcripts for ACAT were expressed at a relatively constant level in all three cell types. The expression of mRNA for glyceraldehyde phosphate dehydrogenase, the control gene in this study, was also expressed at a constant level in each of the cell types. The increase in ACAT mRNA was accompanied by changes in the kinetic properties of the enzyme. Specifically, there was a 14-fold increase in Vmax and a 71% decrease in Km with respect to oleoyl coenzyme A. Although not definitive, the concomitant changes in mRNA and Vmax strongly suggest that the amount of ACAT protein increases upon conversion of monocytes to macrophages. The data show that ACAT in monocytes can be regulated by both substrate and gene expression.

Regulation of human stearoyl-CoA desaturase by omega-3 and omega-6 fatty acids: Implications for the dietary management of elevated serum triglycerides.

BACKGROUNDnPolyunsaturated fatty acids lower serum triglycerides by a mechanism that may involve the inhibition of stearoyl-CoA desaturase (SCD).nnnOBJECTIVEnWe sought to evaluate the effects of serum fatty acids on 1) the SCD index in a controlled clinical setting, and 2) SCD regulation in Hep G2 cells.nnnMETHODSnThe SCD index was determined in 23 subjects randomly sequenced through 3 diets for 6 weeks in a crossover study. Diets were variably enriched with n-3 and n-6 polyunsaturated fatty acids; notably, monounsaturated fatty acids were held constant. Effects of linoleic acid (LA), α-linolenic acid (ALA), and eicosapentaenoic acid (EPA) on mRNA levels of SCD, fatty acid elongases 5 and 6 (Elovl5 and Elovl6), fatty acid synthase, carnitine palmitoyltransferase-1, and sterol response element binding protein-1c were investigated in Hep G2 cells after 24-hour incubations.nnnRESULTSnThe SCD indexes C18:1/18:0 and C16:1/C16:0 were significantly (P < .0001) correlated with serum TG with R(2) values of 0.71 and 0.58. The correlation was negatively associated with LA and positively associated with ALA. LA and EPA decreased SCD mRNA (EC(50) of 0.50 and 1.67μM), whereas ALA did not. Likewise, LA and EPA decreased sterol response element binding protein-1c mRNA (EC(50) of 0.78 and 1.78μM), but ALA did not. Similar results were observed for Elovl6. GW9662, a peroxisome proliferation activator receptor antagonist, did not obviate the effects of LA and EPA on SCD mRNA.nnnCONCLUSIONSnDiets enriched in LA, ALA, and by metabolic inference EPA, can regulate SCD activity at the level of transcription, a nutritional intervention that may be useful in the management of increased levels of serum triglycerides in cardiometabolic disorders.

Safety assessment of EPA-rich oil produced from yeast: results of a 90-day subchronic toxicity study.

The safety of eicosapentaenoic acid (EPA) oil produced from genetically modified Yarrowia lipolytica yeast was evaluated following 90 days of exposure. Groups of rats received 0 (olive oil), 98, 488, or 976 mg EPA/kg/day, or GRAS fish oil or deionized water by oral gavage. Rats were evaluated for in-life, neurobehavioral, anatomic and clinical pathology parameters. Lower serum cholesterol (total and non-HDL) was observed in Medium and High EPA and fish oil groups. Lower HDL was observed in High EPA and fish oil males, only at early time points. Liver weights were increased in High EPA and Medium EPA (female only) groups with no associated clinical or microscopic pathology findings. Nasal lesions, attributed to oil in the nasal cavity, were observed in High and Medium EPA and fish oil groups. No other effects were attributed to test oil exposure. Exposure to EPA oil for 90 days produced no effects at 98 mg EPA/kg/day and no adverse effects at doses up to 976 mg EPA/kg/day. The safety profile of EPA oil was comparable to that of GRAS fish oil. These results support the use of EPA oil produced from yeast as a safe source for use in dietary supplements.

Acyl CoA:cholesterol acyltransferase (ACAT) inhibitors: heterocyclic bioisosteres for the urea group in DuP 128

Abstract A series of compounds bearing two heterocyclic substituents were evaluated for inhibition of the ACAT enzyme. One heterocyclic group was chosen to mimic the urea group in our clinical candidate, DuP 128. Of the several groups examined, aminobenzoxazoles proved to be the most potent in terms of inhibition of ACAT in J774 macrophage cells.

Acyl CoA:cholesterol acyltransferase (ACAT) inhibitors: ureas bearing heterocyclic groups bioisosteric for an imidazole

Abstract A series of compounds bearing heterocyclic substituents were prepared, and evaluated for inhibition of the ACAT enzyme. The heterocyclic groups were compared in terms of in vitro potency against their diarylimidazole analogues. Data for the purposes of QSAR were also collected. Our goal is a systemic ACAT inhibitor, which would be a potential antihypercholesterolemic and antiatherosclerotic agent.

ACAT inhibitors derived from hetero-Diels-Alder cycloadducts of thioaldehydes

Acyl-CoA:cholesterol acyltransferase (ACAT) is the enzyme largely responsible for intracellular cholesterol esterification. A systemic inhibitor of ACAT is believed to be able to slow or even reverse the atherosclerotic process. Towards that goal, a series of cyclic sulfides, derived from the hetero-Diels-Alder reaction of thioaldehydes with 1,3-dienes, and bearing carboxamide substituents, were prepared and evaluated for in vitro (in several tissues and species) and ex vivo ACAT inhibition. Minor changes in subsequent structure were found to have a significant effect in optimization of the biological activity of this series of compounds.

Safety assessment of EPA-rich triglyceride oil produced from yeast: Genotoxicity and 28-day oral toxicity in rats

The 28-day repeat-dose oral and genetic toxicity of eicosapentaenoic acid triglyceride oil (EPA oil) produced from genetically modified Yarrowia lipolytica yeast were assessed. Groups of rats received 0 (olive oil), 940, 1880, or 2820 mg EPA oil/kg/day, or fish oil (sardine/anchovy source) by oral gavage. Lower total serum cholesterol was seen in all EPA and fish oil groups. Liver weights were increased in the medium and high-dose EPA (male only), and fish oil groups but were considered non-adverse physiologically adaptive responses. Increased thyroid follicular cell hypertrophy was observed in male high-dose EPA and fish oil groups, and was considered to be an adaptive response to high levels of polyunsaturated fatty acids. No adverse test substance-related effects were observed on body weight, nutritional, or other clinical or anatomic pathology parameters. The oil was not mutagenic in the in vitro Ames or mouse lymphoma assay, and was not clastogenic in the in vivo mouse micronucleus test. In conclusion, exposure for 28 days to EPA oil derived from yeast did not produce adverse effects at doses up to 2820 mg/kg/day and was not genotoxic. The safety profile of the EPA oil in these tests was comparable to a commercial fish oil.

Novel 4,4-bis(trifluoromethyl) imidazolines as stereospecific and orally active acyl coa: Cholesterol acyltransferase (ACAT) inhibitors and antihypercholesterolemic agents

A new class of very potent, systemically-active ACAT inhibitors based on a 4,4-bis(trifluoromethyl)imidazoline ring has been discovered. Compound 6 and its R-enantiomer 6a exhibited very potent oral activities in lowering the serum cholesterol in the animals.

DMP 504, a Novel Hydrogel Bile Acid Sequestrant: I. Equilibrium Binding Properties and Computer Simulation of Human Bile Flow

DMP 504 is a novel bile acid sequestrant under development for the treatment of primary hypercholesterolemia. The resin is a soft‐textured “hydrogel” that is synthesized from 1,10‐dibromodecane and 1,6‐diaminohexane. The equilibrium binding parameters for DMP 504 have been determined and compared to cholestyramine (CS) with respect to the major trihydroxy bile acid, glycocholate (GC), and the major dihydroxy bile acid, glycochenodeoxycholate (GCDC). DMP 504 had a greater maximum binding capacity (Bmax) than CS for GC (5.47 ± 0.06 vs. 2.76 ± 0.17 moles/kg) and GCDC (5.71 ± 0.14 vs. 3.26 ± 0.11 moles/kg). DMP 504 had a greater affinity, i.e., a lower Kd, than CS for GC (1.78 ± 0.04 vs. 5.24 ± 0.64 mM) and GCDC (0.19 ± 0.01 vs. 0.52 ± 0.06 mM). Similar values were obtained for the taurine conjugates of cholate and chenodeoxycholate. Since the interaction of bile acids with DMP 504 was highly cooperative, the binding isotherms were analyzed with a model that included a cooperativity parameter (W) to allow for interactions between adjacently bound bile acids. The DMP 504 binding isotherms showed greater cooperativity than CS for GC (5.10 ± 0.42 vs. 1.81 ± 0.47) and GCDC (6.28 ± 1.68 vs. 2.40 ± 0.76). A mathematical model of human bile flow, using the values for Bmax, Kd, and W determined in this study predicted that DMP 504 would be approximately threefold more potent than CS in a clinical setting. Drug Dev. Res. 41:58–64, 1997.