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The current investigations on fatty acids are focused on long chain fatty acids, trans fatty acids (TFA) and conjugated fatty acids (CFA), especially isomers of linoleic acid (CLA). This paper deals with the origins of TFA and CLA and their physiological significance. Furthermore an overview is given of analytical procedures of both TFA and CLA. In addition the contents and isomeric distribution of these groups of fatty acids in foods are presented.

Recent studies showed that conjugated linoleic acids (CLA) lower triacylglycerol concentrations in the milk of lactating animals. This study was performed to determine the reasons for this phenomenon; we also investigated whether there is a relation between altered lipid metabolism in the liver and the reduction in milk triacylglycerols in rats fed CLA. Two groups of female rats were fed diets containing 0 [sunflower oil (SFO) group] or 14.7 g/kg diet of a CLA mixture (CLA group) at the expense of sunfiower oil during growth, pregnancy, and lactation. CLA-fed rats had 49 and 80% lower mRNA concentration and activity of fatty acid synthase, respectively, a 51% lower mRNA concentration of lipoprotein lipase (LPL) in their mammary glands at d 17 of lactation, and a 46% lower milk fat content than SFO rats (P < 0.05). Although CLA rats had lower concentrations of triacylglycerols in the liver than SFO rats (20.8 [+ or -] 2.6 vs. 62.6 [+ or -] 27.7 [micro]mol/g, P < 0.05), concentrations of triglycerides in plasma, which are the substrates of LPL, did not differ between the groups. Moreover, the number of pups per litter, litter weights, and pup weights at d 17 of lactation were 41, 35, and 22% lower, respectively, in the CLA group than in the SFO group. In conclusion, the present study suggests that dietary CIA reduces triacylglycerol concentrations in the milk via reduced de novo fatty acid synthesis in the mammary gland and an impaired uptake of fatty acids from lipoproteins into the mammary gland. This might be the reason for reduced growth rates and an increased mortality of suckling pups. KEY WORDS: * conjugated linoleic acid * lactation * mammary gland * liver * rat

A simple and reproducible method which provides the simultaneous determination of PAHs and hetero-PAHs (N,S,O) and their metabolites in contaminated soils has been developed. Contaminants extracted from the soil sample were separated by polarity and acid-base characteristics using solid phase extraction (SPE) on silica gel and a strong basic anion exchange material. A subfraction containing PANHs and neutral metabolites was subsequently fractionated into neutral and basic compounds using a strong acidic cation exchange material. The identification and quantification was performed using different GC and HPLC methods. A method validation was carried out for 21 PAHs, 22 hetero-PAHs, and 19 metabolites in a five-level matrix calibration. Uncontaminated soil (AhA1-layer/compost mixture) was spiked with the chosen standard compounds. The method showed good linearity (coefficient of correlation) and high precision (coefficient of variation) for major and minor compounds over a wide range of concentration as well as high sensitivity (limit of detection). The method was successfully applied to different authentic tar oil contaminated sites. Aside from the typical tar oil PAHs, hetero-PAHs and metabolites predominantly with ketonic or quinonic structure were identified on a mg/kg concentration level.

This investigation gives an overview of the concentrations of naturally occurring androgens, progestogens, corticesteroids, and their precursors and metabolites in meat from bulls and steers. A recently developed gas chromatography-mass spectrometry (GC-MS) method with improved sensitivity for steroid analysis was used. Eighty-two beef samples were analyzed using the GC-MS method. Beef from bulls contained higher concentrations of testosterone, which is an anabolic androgen, and its metabolite epitestosterone (P < .01) and the androgen precursor dehydroepiandrosterone (P < .05) than beef from steers. Beef from steers contained higher (P < .05) concentrations of the basic hormone precursor pregnenolone and cortisol, which is a catabolic corticosteroid, than beef from bulls. A classification of an unknown beef sample to one of the categories (bull or steer) was possible in most cases (>90%) using a masculinity index (MI) that was calculated using the concentrations of testosterone, epitestosterone, and pregnenolone. Because the hormonal status of beef cattle is related to meat quality characteristics, such as tenderness or fat and protein distribution, the MI may contribute to meat quality assessment and meat quality control. Key Words: Beef, Steers, Bulls, Androgens, Progestogens, Corticoids

It is important to understand collagen, the key component of muscle connective tissue and thus important in meat's quality. An investigation of the development of muscle collagen cross-linkage by finding hydroxylsylpyridinoline and lysylpyridinoline contents of longissimus dorsi, semitendinosus and extensor carpi ulnaris muscles showed an age-related increase in pyridinoline content in intramuscular collagen. Cross-link formation was influenced by sex and feeding intensity. Differences in pyridinoline content were exhibited by epimysia.