Liver, sampling

G. P. Blanch, A. Glausch, V. Schurig, R. Serrano and M. J. Gonzalez, Quantification and determination of enantiomeric ratios of chkal PCB 95, PCB 132 and PCB 149 in shark liver samples (C. coelolepis) from the Atlantic ocean , 7. High Resolut. Chromatogr. 19 392-396 (1996). 

In the case of dmg interactions involving metabolic inhibition, little increase in the substrate concentration is expected when the inhibition constant (K ) determined in in vitro studies using human liver samples is larger than the inhibitor concentration in vivo. Various approaches have been adopted using mathematical models in attempts to quantitatively predict in vivo dmg interactions from in vitro data [5]. 

Because of the possibility that the herbicide alachlor could adulterate food if either poultry or livestock consumed contaminated materials, Lehotay and Miller evaluated three commercial immunoassays in milk and urine samples from a cow dosed with alachlor. They found that milk samples needed to be diluted with appropriate solvents (1 2, v/v) to eliminate the matrix effect. One assay kit (selected based on cost) was also evaluated for use with eggs and liver samples from chickens. Egg and liver samples were blended with acetonitrile, filtered, and diluted with water. Linear calibration curves prepared from fortified egg and liver samples were identical... 

Franek et al developed an immunoassay for sulfadimidine, but they found that milk samples required dilution (1 100), and tissues required dilutions of 1 200 to 1 4000. The LOD was 0.02 pg kg from the buffer calibration curve with the IC50 at 0.15 pgkg The assay measured levels in milk from 10 to 100 pgkg with satisfactory precision. In swine muscle, kidney, and liver samples, levels from 20 to 500 pg kg could be measured when 2 g of tissue were homogenized with 20 mL of buffer and then diluted 1 20. 

Kennedy et al. developed a lasalocid immunoassay for application to residues in chicken meat and liver samples. The antibody was specific and did not cross-react with salinomycin, maduramicin, or monensin. Sample preparation consisted of homogenization in aqueous acetonitrile, removal of fat from an aliquot of the aqueous acetonitrile by hexane extraction, and evaporation of acetonitrile. The sample was then reconstituted with assay buffer. Liver required an additional solid phase extraction step. The LOQ was 0.02 xgkg for muscle and 0.15 agkg for liver. These workers were able to use the system to determine the half-life of lasalocid in the tissues. 

Arene with aromatic rings ranging from one to six. i.e. r>-xylene to benz[ Ianthracene, were determined and only the compounds listed here were found in significantly higher concentrations in test fish, bSkin and liver samples were pooled from three fish at each analysis muscle samples were analyzed individually. 

Example A potential drug and its metabolite in a liver sample are quantified by internal standardization with trideuterated standards for both compounds (Fig. 12.4). [25] Under these conditions it neither presents a problem that both analytes and their isotopic standards are almost co-eluting from the LC column, nor does the completely unspecific TIC play a role. If required for sensitivity reasons, this analysis could also have been performed in the SIM mode using the m/z values of the RICs shown. 

Comparative Toxicokinetics. Metabolic pathways and mechanisms of hepatotoxicity of carbon tetrachloride have been the subject of many studies in intact animals and in vitro, and are therefore better understood than for many other chemicals. However, there are apparently no data on metabolism of carbon tetrachloride in humans. It would be valuable to conduct in vitro experiments with human liver samples and hepatocytes to determine whether metabolic pathways and toxic metabolites are similar to those found in animals. It would also be beneficial to identify an animal model in which MFO systems develop in uteroas they do in the human fetus. 

Species comparisons of hepatic peroxisomal proliferation have also included studies of human and non-human primate primary hepatocyte cultures. Hepatocytes isolated from Wistar-derived rats (180-220 g), male Alderley Park guinea-pigs (400-500 g), male marmosets (350-500 g) and three human liver samples (renal transplant donors) were treated with 0-0.5 mM mono(2-ethylhexyl) phthalate for 72 h (Elcombe Mitchell, 1986). While there was a concentration-dependent induction of cyanide-insensitive palmitoyl-CoA oxidation in rat hepatocytes, no induction was observed in guinea-pig or human hepatocytes and only small non-concentration-dependent effects were observed in marmoset hepatocytes. Metabolite VI induced cyanide-insensitive palmitoyl-CoA oxidation and lauric acid hydroxylation in cultured... 

Hepatocytes were isolated from male Fischer 344 rats and from two human liver samples (liver surgery patients). Treatment with 200 pM mono(2-ethylhexyl) phthalate for either 48 or 72 h induced carnitine acetyltransferase activity in cultured rat but not human hepatocytes (Butterworth et al, 1989). 

Peroxisome proliferators have also been shown to induce replicative DNA synthesis in cultured rodent hepatocytes (lARC, 1995). In contrast, several peroxisome proliferators have failed to induce replicative DNA s mthesis in human hepatocyte cultures (Doull et al., 1999). Hepatocytes were isolated from male Wistar-derived rats and from three human liver samples (liver transplantation donors) and treated with 2-ethylhexanoic acid and some other peroxisome proliferators for 72 h (Elcombe et al, 1996). While 2-ethylhexanoic acid induced replicative DNA s5mthesis in cultured rat hepatocytes, no effect was observed in human hepatocytes. Hepatocytes were isolated from male Fischer 344 rats and three humans and treated in culture with 250-2000 pM mono(2-ethylhexyl) phthalate (Hasmall et al, 1999). Increased peroxisomal (O-oxi-dation (at 250-750 pM), replicative DNA s mthesis (at 500-1000 pM), and inhibition of apoptosis (at 250-1000 pM) were observed in rat hepatocytes. None of these parameters was affected by mono(2-ethylhexyl) phthalate in human hepatocytes. 

A similar relationship between PCDF isomers retained and apparently excreted has been observed for patients with the Yusho disease, an intoxication by a rice oil contaminated with PCBs and PCDFs. The contaminated rice oil and liver samples from two of the patients were analyzed and all the major PCDFs were identified. A comparison revealed that none of the isomers retained had two vicinal hydrogenated C-atoms in any of the two... 

Aksoy,., J. Klener, and Richard M. Weinshilboum. 1993. "Catechol-O-Methyl-transferase Pharmacogenetics Photoaffinity Labelling and Western Blot Analysis of Human Liver Samples." Pharmacogenetics 3 116-22. 

CYPlAl appears to be expressed at very low levels (if at all) in human liver. Wrighton and Stevens (1992) report that only one of 50 human liver samples contained protein immunoreactive to an antibody raised against rat CYPlAl. Murray et al. (1993) used CYPlAl-specific and CYPlA2-specific antipeptide antibodies and found no evidence for CYPlAl expression in human liver microsomes. However, McKinnon. (1991) reported detection of CYPlAl mRNA in 11 of 23 human liver samples studied. 

Yamano et al. (1990) analysed CYP2B6 mRNA levels and protein levels using a cDNA probe and an anti-rat CYP2B1 antibody developed in rabbits, respectively. Thirteen human liver samples were studied and CYP2B6 mRNA and protein were present at high levels in only two liver samples. 

All intoxication cases described above demonstrate clearly that safety evaluation of pharmacologically active compounds to which consumers are exposed as residues in food must be based on both toxicological and pharmacological criteria. Consumption of 100 g liver containing clenbuterol in concentration levels as determined in liver samples contaminated with 160-500 ppb, would exceed the pharmacological effect level of 5 g per person (47). 

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