Contrasting effects of t10,c12- and c9,t11-conjugated linoleic acid isomers on the fatty acid profiles of mouse liver lipids.

The purpose of this study was to examine the effects of two purified isomers of CLA (c9,t11-CLA and t10,c12-CLA) on the weights and FA compositions of hepatic TG, phospholipids, cholesterol esters, and FFA. Eight-week-old female mice (n = 6/group) were fed either a control diet or diets supplemented with 0.5% c9,t11-CLA or t10,c12-CLA isomers for 8 wk. Weights of liver total lipids and those of individual lipid fractions did not differ between the control and the c9,t11-CLA groups. Livers from animals fed the t10, c12-CLA diet contained four times more lipids than those of the control group; this was mainly due to an increase in the TG fractions (fivefold), but cholesterol (threefold), cholesterol esters (threefold), and FFA (twofold) were also significantly increased. Although c9,t11-CLA did not significantly alter the weights of liver lipids when compared with the control group, its intake was associated with significant reductions in the weight percentage (wt% of total FAME) of 18:1n-9 and 18:1n-7 in the TG fraction and with significant increases in the weight percentage of 18:2n-6 in the TG, cholesterol ester, and phospholipid fractions. On the other hand, t10,c12-CLA intake was linked with a significant increase in the weight percentage of 18:1n-9 and a decrease in that of 18:2n-6 in all lipid fractions. These changes may be the result of alterations in the activity of delta9-desaturase (stearoyl CoA desaturase) and the enzymes involved in the metabolism of 18:2n-6. Thus, the two isomers differed not only in their effects on the weights of total liver lipids and lipid fractions but also on the FA profile of the lipid fractions.

Trans-10,cis-12 CLA increases liver and decreases adipose tissue lipids in mice: possible roles of specific lipid metabolism genes.

Although consumption of CLA mixtures has been associated with several health effects, less is known about the actions of specific CLA isomers. There is evidence that the t10,c12-CLA isomer is associated with alterations in body and organ weights in animals fed CLA, but the mechanisms leading to these changes are unclear. The purpose of this study was to determine the effects of two commonly occurring isomers of CLA on body composition and the transcription of genes associated with lipid metabolism. Eight-week-old female mice (n = 11 or 12/group) were fed either a control diet or diets supplemented with 0.5% c9,t11-CLA or t10,c12-CLA isomers or 0.2% of the peroxisome proliferator-activated receptor alpha (PPARalpha) agonist fenofibrate for 8 wk. Body and retroperitoneal adipose tissue weights were significantly lower (6-10 and 50%, respectively), and liver weights were significantly greater (100%) in the t10,c12-CLA and the fenofibrate groups compared with those in the control group; body and tissue weights in the c9,t11-CLA group did not differ from those in the control group. Livers from animals in the t10,c12-CLA group contained five times more lipids than in the control group, whereas the lipid content of the fenofibrate group did not differ from that in the control group. Although fenofibrate increased the mRNA for PPARalpha, t10,c12-CLA decreased it. These results suggest that PPARalpha did not mediate the effects of t10,c12-CLA on body composition. The CLA isomers and fenofibrate altered mRNA levels for several proteins involved in lipid metabolism, but the most striking difference was the reduction of mRNA for leptin and adiponectin in the t10,c12-CLA group. These initial results suggest that changes associated with energy homeostasis and insulin action may mediate the effects of t10,c12-CLA on lipid metabolism.

Similar effects of c9,t11-CLA and t10,c12-CLA on immune cell functions in mice.

Published results regarding the effects of CLA on immune cell functions have ranged from stimulation to inhibition. In those studies, a mixture of CLA isomers were used, and food intake was not controlled. We have examined whether the discrepancies in the results of earlier studies may be due to the lack of controlled feeding and whether the two isomers of CLA may differ in their effects on immune cell functions. Three groups of C57BL/6 female mice were fed either a control, c9,t11-CLA-, or t10,c12-CLA (0.5 wt%)-supplemented diet, 5 g/d, for 56 d. At the end of the study, the number of immune cells in spleens, bone marrows, or in circulation; proliferation of splenocytes in response to T and B cell mitogens; and prostaglandin secretion in vitro did not differ among the three groups. Both CLA isomers significantly increased in vitro tumor necrosis factor alpha and interleukin (IL)-6 secretion and decreased IL-4 secretion by splenocytes compared to those in the control group. Thus, the two CLA isomers had similar effects on all response variables tested. The discrepancies among the results from previous studies did not seem to be caused by the differences in the isomer composition of CLA used.

Dietary supplementation with conjugated linoleic acid increased its concentration in human peripheral blood mononuclear cells, but did not alter their function.

The purpose of this study was to examine if conjugated linoleic acid (CLA) supplementation of diets would alter fatty acid (FA) composition and function of peripheral blood mononuclear cells (PBMC). Seventeen women, 20-41 yr, participated in a 93-d study conducted at the Metabolic Research Unit. The same diet (19, 30, and 51% energy from protein, fat, and carbohydrate, respectively) was fed to all subjects throughout the study. Seven subjects (control group) supplemented their diet with six daily capsules (1 g each) of placebo oil (sunflower) for 93 d. For the other 10 subjects (CLA group), the supplement was changed to an equivalent amount of Tonalin capsules for the last 63 d of the study. Tonalin provided 3.9 g/d of a mixture of CLA isomers (trans-10,cis-12, 22.6%; cis-11,trans-13, 23.6%; cis-9,trans-11, 17.6%; trans-8,cis-10, 16.6%; other isomers 19.6%), and 2.1 g/d of other FA. PBMC isolated on study days 30 and 90 were used to assess intracellular cytokines by flow cytometry, secreted cytokines, and eicosanoid by enzyme-linked immonosorbent assay, and FA composition by gas-liquid chromatography. After supplementation, total CLA concentration increased from 0.012 to 0.97% (P < 0.0001) in PBMC lipids, but it did not significantly alter the concentration of other FA. CLA supplementation did not alter the in vitro secretion of prostaglandin E2, leukotriene B4, interleukin-1beta (IL-1beta), or tumor necrosis factor alpha (TNFalpha) by PBMC simulated with lipopolysaccharide, and the secretion of IL-2 by PBMC stimulated with phytohemagglutinin. Nor did it alter the percentage T cells producing IL-2, interferon gamma, and percentage of monocytes producing TNFalpha. The intracellular concentration of these cytokines was also not altered. None of the variables tested changed in the control group. Our results show that CLA supplementation increased its concentration in PBMC lipids, but did not alter their functions.

Determination of serum levels of thirteen human immunodeficiency virus-suppressing drugs by high-performance liquid chromatography.

Two high-performance liquid chromatographic methods using UV detection are presented for the determination of two different groups (A and B) of drugs used in the suppression of human immunodeficiency virus (HIV). Group A is comprised of six nucleosidic reverse transcriptase inhibitors, viz. zalcitabine, lamivudine, stavudine, didanosine, zidovudine and ziagen. Group B consists of seven drugs four of which are protease inhibitors (PIs) and three of which are non-nucleosidic reverse transcriptase inhibitors (NNRTIs). The PIs are: indinavir, nelfinavir, saquinavir and ritonavir. The NNRTIs are: nevirapine, delavirdine and efavirenz. Groups A and B require separate aliquots of serum for extraction and must be chromatographed separately.

Amiodarone-associated changes in human neutrophils.

Amiodarone and its major metabolite, desethylamiodarone, were measured in the plasma, white blood cells (WBCs) and red blood cells (RBCs) of 14 patients receiving chronic amiodarone therapy. The mean plasma concentrations (+/- standard error of the mean) of amiodarone and desethylamiodarone were 2.4 +/- 0.6 and 1.6 +/- 0.4 microgram/ml, respectively. The drug level in the WBCs was 62 +/- 12 micrograms/g protein during the early loading phase and 106 +/- 33 micrograms/g protein during maintenance phase of amiodarone therapy. Desethylamiodarone concentration in the WBCs was 42 +/- 18 and 190 +/- 33 micrograms/g protein during the loading and maintenance phases, respectively. Although a trend in WBC to plasma concentration was seen, there was no linear correlation between these levels. In 1 patient with severe neuropathy, biopsy of the nerve and muscle showed high concentrations of both amiodarone and desethylamiodarone. Although there was a decrease in tissue drug levels, proportionately high tissue:plasma drug levels were detected at the time of necropsy approximately 6.5 months after amiodarone was discontinued in this patient. Neutrophils from all patients receiving chronic amiodarone therapy showed multiple myelin-like polymorphic inclusion bodies (onionoid bodies) upon electron microscopic examination. Our observations suggest that WBC drug concentrations and electron microscopic changes may provide a means of correlating tissue concentrations and of following patients receiving chronic amiodarone therapy.

Pharmacokinetics, antiarrhythmic effects, and tissue concentrations of amiodarone and desethylamiodarone in dogs with acute coronary artery occlusion.

A single bolus of 5 or 40 mg/Kg of amiodarone was injected 24 hours after inducing coronary artery occlusion in the closed-chest dog preparation. Plasma pharmacokinetic profile was determined and the calculated t1/2 beta of 3.5 +/- 2.8 and 3.2 +/- 0.6 hour after 5 or 40 mg/Kg dose, respectively, were obtained. The major metabolite, desethylamiodarone, was detected within 15 minutes of the single bolus of amiodarone. At 6 hours after amiodarone administration, the animals were killed and tissue concentrations of amiodarone and desethylamiodarone were measured. Two additional peaks in the HPLC chromatograms were observed in plasma and tissue samples of most dogs given 40 mg/Kg I.V. amiodarone and these most likely are due to unidentified metabolites of the drug. The highest drug concentration was found in the lungs. Tissue to plasma drug rations suggested that accumulation of amiodarone and perhaps desethylamiodarone was different for different tissues. Ventricular arrhythmias were not abolished by either of the two doses of amiodarone; however, there was a gradual and statistically significant decrease in the number of ventricular premature beats and ventricular tachycardia beats over the six-hour period after a single 40 mg/Kg I.V. bolus. At the time of reduction in the arrhythmia frequency, tissue levels of both amiodarone and desethylamiodarone in the border and infarct zone of the myocardium were approximately 50% as high as in the normal zone. Plasma drug levels did not correlate well with tissue concentrations. However, there was an excellent correlation between drug levels in WBCs and various tissues except the lung. It is concluded that amiodarone is rapidly metabolized into desethylamiodarone and at least two other unidentified compounds; a large dose of amiodarone is necessary to produce some decrease in ventricular arrhythmias associated with acute coronary artery occlusion; tissue concentrations may be better correlated with drug levels in WBCs than in plasma, and coronary artery occlusion does not affect acute pharmacokinetic profile of the drug.