Liver Tissue Concentrations Research Articles

Diagnosis of Zinc Phosphide Poisoning in Chickens Using a New Analytical Approach

Approximately 200 chickens were found dead after the flooring of a slat-and-litter house was breached. No clinical signs of illness were observed in the surviving birds. During necropsy, rolled oats were found in the chickens' crops and gizzards, and the contents had a petroleum-like odor. Histopathologic examination revealed severe pulmonary edema and congestion of the chickens' lungs, hearts, livers, and kidneys. Based on the history and necropsy findings, zinc phosphide exposure was suspected. Diagnosis of zinc phosphide poisoning has previously been based on history of exposure, identification of the bait material in the gastrointestinal tract, and chemical detection of phosphine gas. However, currently available diagnostic methods are nonconfirmatory, and may produce false positive results. The objective of this case report was to determine whether the sudden death described in these chickens was caused by the ingestion of zinc phosphide, by developing a sensitive and highly specific gas chromatography/mass spectrometry (GC/MS) methodology for analysis of the gastrointestinal samples submitted to the laboratory. It was also found that the determination of zinc concentrations in liver or kidney tissue or stomach contents is not a reliable indicator of zinc phosphide poisoning.

Beyond vitamin E supplementation: An alternative strategy to improve vitamin E status

Vitamin E has many reported health effects and is recognized as the most important lipid-soluble, chain-breaking antioxidant in the body. Vitamin E has also been reported to play a regulatory role in cell signalling and gene expression. Epidemiological studies show that high blood concentrations of vitamin E are associated with a decreased risk of cardiovascular diseases and certain cancers. Yet, high doses of supplemental vitamin E have been associated with an elevated risk of heart failure and all-cause mortality. Therefore, establishing alternative strategies to improve vitamin E status without potentially increasing mortality risk may prove important for optimal nutrition. To identify dietary phenolic compounds capable of increasing blood and tissue concentrations of vitamin E, selected polyphenols were incorporated into standardized, semi-synthetic diets and fed to male Sprague-Dawley rats for 4 weeks. Blood plasma and liver tissue concentrations of alpha-T and gamma-Twere determined. The flavanols (+)-catechin and (-)-epicatechin, the flavonol quercetin, and the synthetic preservative butylated hydroxytoluene (BHT) markedly elevated the amount of alpha-T in plasma and liver. The sesame lignan sesamin and cereal alkylresorcinols substantially increased the concentrations of gamma-T, but not alpha-T, in the liver. Sesamin also increased gamma-T concentrations in plasma. In order to study the impact of selected polyphenols on the enzymatic degradation of vitamin E, HepG2 cells were incubated together with phenolic compounds in the presence of tocopherols and the formation of metabolites was determined. Sesamin, at concentrations as low as 2 microM, almost completely inhibited tocopherol side-chain degradation and cereal alkylresorcinols inhibited it, dose-dependently (5-20 microM), by 20-80%. BHT, quercetin, (-)-epicatechin, and (+)-catechin had no effect on tocopherol-omega-hydroxylase activity in HepG2 cells. In order to confirm the inhibition of gamma-T metabolism by sesame lignans in humans, sesame oil or corn oil muffins together with deuterium-labelled d6-alpha-Tand d2-gamma-Twere given to volunteers. Urine samples were collected for 72 h and analysed for deuterated and non-deuterated tocopherol metabolites. Consumption of sesame oil muffins significantly reduced the urinary excretion of d2-gamma-CEHC and total (sum of labelled and unlabelled) gamma-CEHC. Overall, the findings from these studies show that the tested dietary phenolic compounds increase vitamin E concentrations through different mechanisms and, thus, have the potential to improve vitamin E status without the use of vitamin E supplements.

Identification of N, N-dimethylamphetamine formed by methylation of methamphetamine in formalin-fixed liver tissue by multistage mass spectrometry

Methamphetamine is methylated in the presence of unbuffered formalin solutions within hours at room temperature. The product, N, N-dimethylamphetamine, is also found in human liver exposed to methamphetamine followed by incubation with formalin. In the present study, a direct mass spectrometric method was developed to identify N, N-dimethylamphetamine in human liver before and after treatment with formalin. Human liver samples were obtained from four deaths that were investigated by the West Virginia Office of Chief Medical Examiner. Full toxicological analysis was conducted on samples from the decedents and methamphetamine was among the positive findings in each case. The method used to expose liver tissue to formaldehyde involved treating a small piece of liver from each case with formalin solution (20% v/v) for 24 h at room temperature. The formalin treated tissues were homogenized and the resulting suspension was sonicated for 5 min, and then centrifuged. Supernatant aliquots were directly analyzed by electrospray ionization (ESI) mass spectrometry without chromatographic isolation. Positive ion multistage mass spectra recorded in MS, MS/MS and MS/MS/MS (MS 3) modes were used to confirm the presence of N, N-dimethylamphetamine and methamphetamine in the mixture. Liver tissue not treated with formalin did not contain a detectable level of N, N-dimethylamphetamine. Decreases in methamphetamine concentrations in liver tissue resulting from treatment with formalin were measured using deuterium-labeled methamphetamine as internal standard. The method can be completed in less than 2 h on thawed tissue. The results suggest that the process of fixing tissues with formalin may lead to false negative findings for methamphetamine.

In vivo biochemical changes in liver and gill of Clarias batrachus during cypermethrin exposure and following cessation of exposure

The sublethal effect of a synthetic pyrethroid, cypermethrin on total protein, amino acids, ammonia, glycogen, and enzymes like aminotransaminases (AIAT, AAT), glutamate dehydrogenase, and glycogen phosphorylases (a and ab) was studied in physiological important tissues viz; liver and gill tissues of freshwater teleost air breathing fish, Clarias batrachus. The study was conducted during exposure of 1/3 (33%) of LC 50 concentration and followed by cessation of exposure. Thirty-six fish were exposed to 0.07 mg/L cypermethrin for 10 days. After 10 days, 18 fish were released to freshwater and kept in the same for 10 days (recovery group). Thirty-six fish were kept in freshwater as control batch. Protein content in liver tissues decreased at the end of 1st and 5th day followed by slight increase at the end of 10th day. Gill tissue showed statistical significant decrease ( P < 0.001) in protein content during exposure period of 10 days. Recovery in protein content was observed to a large extent in both the tissues. Total free amino acids were increased in liver and gill tissues throughout the treatment period, recovery response was seen after cessation of exposure. Ammonia level was decrease in both the tissues throughout the exposure period except in liver tissue at the end of 1st day of exposure. Recovery response was exhibited by both the tissues. A decreased in glycogen content of liver tissue was observed during exposure period, gill tissue also showed decrease in glycogen at the end of 1st and 5th day followed by increase at the end of 10th day of exposure period. When the fish were transferred to freshwater, recovery in glycogen content was noted. The activity level of alanine, aspartate aminotransaminase, glutamate dehydrogenase, and phosphorylases (a, ab) was increased in both the tissues, followed by recovery response after released of fish into freshwater. The present study showed that cypermethrin caused alterations in certain biochemical mechanisms of C. batrachus. This fish indicated recovery response when transferred to cypermethrin free water.

Disrupted coordinate regulation of farnesoid X receptor target genes in a patient with cerebrotendinous xanthomatosis

Cerebrotendinous xanthomatosis (CTX), sterol 27-hydroxylase (CYP27A1) deficiency, is associated with markedly reduced chenodeoxycholic acid (CDCA), the most powerful activating ligand for farnesoid X receptor (FXR). We investigated the effects of reduced CDCA on FXR target genes in humans. Liver specimens from an untreated CTX patient and 10 control subjects were studied. In the patient, hepatic CDCA concentration was markedly reduced but the bile alcohol level exceeded CDCA levels in control subjects (73.5 vs. 37.8 +/- 6.2 nmol/g liver). Cholesterol 7alpha-hydroxylase (CYP7A1) and Na+/taurocholate-cotransporting polypeptide (NTCP) were upregulated 84- and 8-fold, respectively. However, small heterodimer partner (SHP) and bile salt export pump were normally expressed. Marked CYP7A1 induction with normal SHP expression was not explained by the regulation of liver X receptor alpha (LXRalpha) or pregnane X receptor. However, another nuclear receptor, hepatocyte nuclear factor 4alpha (HNF4alpha), was induced 2.9-fold in CTX, which was associated with enhanced mRNA levels of HNF4alpha target genes, CYP7A1, 7alpha-hydroxy-4-cholesten-3-one 12alpha-hydroxylase, CYP27A1, and NTCP. In conclusion, the coordinate regulation of FXR target genes was lost in CTX. The mechanism of the disruption may be explained by a normally stimulated FXR pathway attributable to markedly increased bile alcohols with activation of HNF4alpha caused by reduced bile acids in CTX liver.

Evaluation of the influence of S-adenosylmethionine on systemic and hepatic effects of prednisolone in dogs

To evaluate the influence of a 1,4-butanedisulfonate stable salt of S-adenosylmethionine (SAMe) administered orally on clinicopathologic and hepatic effects induced by long-term administration of prednisolone in dogs. 12 healthy dogs. Following a pilot study (4 dogs), 2 groups of 4 dogs received prednisolone (2.2 mg/kg) orally once daily (84-day trial). One group received SAMe (20 mg/kg/d divided in 2 doses) for 42 days and then a placebo for 42 days; the other group received treatments in the reverse order. Before and during the trial, numerous variables were monitored, including serum total alkaline phosphatase (ALP) and glucocorticoid-induced ALP (G-ALP) activities, serum haptoglobin concentration, and total and oxidized glutathione (TGSH and GSSG) and thiobarbiturate-reacting substances (TBARS) concentrations in erythrocytes and liver tissue (days 0, 42, and 84). Hepatic specimens also were examined microscopically. The stable salt of SAMe was biologically available; plasma concentrations of SAMe or prednisolone were not affected by coadministration. Compared with baseline values, serum ALP and G-ALP activities and haptoglobin concentrations increased and erythrocyte GSSG and TBARS concentrations decreased with both treatments. Erythrocyte TGSH concentration decreased with the prednisolone-placebo treatment. Administration of SAMe appeared to conserve erythrocyte TGSH values and did not inhibit hepatocyte glycogen vacuolation but increased hepatic TGSH concentration and improved the hepatic tissue GSSG:TGSH ratio. In dogs, administration of 20 mg of SAMe/kg/d may mitigate the apparent pro-oxidant influences of prednisolone but did not block development of classic clinicopathologic or histologic features of vacuolar hepatopathy.

Specific ssDNA concentration in liver tissue as an index of apoptosis in hepatitis C virus-infected patients

To evaluate the activity of apoptosis in liver tissue and explore its possible association with hepatic necroinflammation and fibrosis as well as serum hepatitis C virus (HCV) load. The studied population included 50 chronic hepatitis C patients (20 women and 30 men, aged 18-66 years). HCV-RNA quantification was performed by two-step real-time quantitative RT-PCR method using the TaqMan technology (reagents of Applera Corporation firm, USA). The morphology of liver tissue was assessed descriptively and scored (necroinflammatory activity and fibrosis). The early apoptosis activity in liver tissue was examined by ssDNA apoptosis ELISA kit, (Chemicon, Germany). The correlation between apoptosis and fibrosis in liver tissue was observed. High intensification of apoptosis was proportional to the increase of fibrosis (ssDNA: 16.65 x 10(-5) microug/g; 12.71 x 10(-5) microg/g), however, this difference was not statistically significant (P>0.05). Activity of apoptosis in the liver tissue, expressed by ssDNA concentration did not depend on hepatic necroinflammatory changes, HCV-RNA viral load, ALT, and AST activity as well as prothrombin time and INR index. Fibrosis in the tissue is closely associated with early apoptosis in HCV-infected patients.

Successful transplantation of a liver from a donor with fatal ethylene glycol poisoning

Successful transplantation of a liver from a donor with fatal ethylene glycol poisoning

Effect of Protein Deficiency on Macroelement and Trace Element Levels of Weanling Rats' Small Intestine and Liver Tissues

Protein energy malnutrition has become a major health issue in developing countries. In the present study, the effect of protein deficiency on the small intestine and liver tissue content of macroelements and trace elements was investigated in weanling rats. Forty-five male weanling Wistar albino rats were divided into three groups. The control group (C) was fed a standard diet containing 25% casein, whereas the two experimental groups E1 and E2 consumed 12% and 3% casein, respectively, over a period of 45 d. The tissue samples were analyzed for zinc, copper, iron, manganese, calcium, and magnesium by atomic absorption spectroscopy. The protein-deficient groups showed increased levels of iron in both tissues and decreased manganese in small intestine tissue from the E1 group. No other differences were found for the other elements. These results suggest that protein deficiency might cause iron accumulation in the liver and intestine and decreases of manganese in the small intestine.

Organochlorine and heavy metal concentrations in blubber and liver tissue collected from Queensland (Australia) dugong ( Dugong dugon)

Tissue samples of liver and blubber were salvaged from fifty-three dugong ( Dugong dugon) carcasses stranded along the Queensland coast between 1996 and 2000. Liver tissue was analysed for a range of heavy metals and blubber samples were analysed for organochlorine compounds. Metal concentrations were similar in male and female animals and were generally highest in mature animals. Liver concentrations of arsenic, chromium, iron, lead, manganese, mercury and nickel in a number of individual animals were elevated in comparison to concentrations previously reported in Australian dugong. Dieldrin, DDT (and its breakdown products) and/or heptachlor epoxide were detected in 59% of dugong blubber samples. In general, concentrations of organochlorines were similar to those reported in dugong 20 years earlier, and were low in comparison to concentrations recorded from marine mammal tissue collected elsewhere in the world. With the exception of lead, the extent of carcass decomposition, the presence of disease or evidence of animal starvation prior to death did not significantly affect dugong tissue concentrations of metals or organochlorines. The results of the study suggest that bioaccumulation of metals and organochlorine compounds (other than dioxins) does not represent a significant risk to Great Barrier Reef dugong populations, particularly in the context of other pressures associated with coastal development and other anthropogenic activities.

Immunotoxicology in wood mice along a heavy metal pollution gradient

We carried out an immunotoxicological field study of wood mice in three populations along a heavy metal pollution gradient. Heavy metal concentrations in liver tissue indicated that exposure to silver, arsenic, cadmium, cobalt and lead decreased with increasing distance from a non-ferrous smelter. Host resistance to the endoparasite Heligmosomoides polygyrus decreased with increasing exposure, while the abundance of tick larvae and the nematode Syphacia stroma was unrelated to heavy metal exposure. Spleen mass was increased at the intermediate and the most polluted sites and was positively correlated with the number of H. polygyrus and tick larvae. Proportion of early apoptotic leukocytes increased towards the smelter and was positively related to cadmium exposure. Red and white blood cell counts and lysozyme activity showed no relationship with metal exposure. All together, our observations suggest negative effects of heavy metal exposure on the immune function of wood mice under field conditions.

In vivo metabolism and kinetics of ethylene glycol monobutyl ether and its metabolites, 2-butoxyacetaldehyde and 2-butoxyacetic acid, as measured in blood, liver and forestomach of mice

Ethylene glycol monobutyl ether (EGBE) causes forestomach hyperplasia and neoplasia in mice when administered chronically by inhalation.The study was initiated to test the physiologically based pharmacokinetic (PBPK) model prediction that 2-butoxyacetaldehyde (BAL), a transient, labile intermediate in the oxidation of EGBE to butoxyacetic acid (BAA), is unlikely to achieve concentrations sufficient to cause DNA damage in target tissues.Male and female B6C3F1 mice were administered a high oral dose of EGBE (600 mg kg−1), and tissues were collected at 5, 15, 45 and 90 min following the dose. The tissues were processed for determination of EGBE, BAL and BAA by gas chromatography-mass spectrometry.BAL was detected at low concentrations in all tissues sampled and at all time points following EGBE administration (about 0.3–33 μM). BAL concentrations were highest in the initial samples (5 min) in all tissues and declined from that point.BAL concentrations in liver and forestomach tissues corresponded to the peak concentrations predicted by an already published PBPK model, and are higher than BAL concentrations that could be achieved by inhalation exposure to EGBE.Mouse inhalation exposure to EGBE is therefore unlikely to generate BAL concentrations in tissues sufficient to initiate a carcinogenic response.

Metal contents of liver parenchyma after percutaneous ethanol injection or radiofrequency ablation in patients with hepatocellular carcinoma before and after trientine hydrochloride therapy

We administered trientine hydrochloride, a drug used in the treatment of Wilson's disease, to patients with hepatocellular carcinoma after radical treatment with percutaneous ethanol injection or radiofrequency ablation, and examined its effect on the reduction of liver-tissue copper content. We enrolled 24 patients with 3 or fewer primary lesions of Child class A or B hepatocellular carcinoma with diameters of 3 cm or less who had undergone radical treatment with percutaneous ethanol injection or radiofrequency ablation. Trientine hydrochloride was orally administered in a single daily dose of 250 mg to 12 patients before a meal (at fasting, group 1) or at a total daily dosage of 750 mg, divided into 3 doses, to 12 patients (group 2). This study was a randomized between-groups comparative study of 12 weeks' duration. We used the particle-induced x-ray–emission method to determine liver-tissue mineral content. Urine copper and serum mineral levels were also measured, and transaminase levels were examined. Liver-tissue copper content decreased significantly, to 160.1 μg/g dry weight, after treatment, compared with the pretreatment level of 306.8 μg/g dry weight ( P < .05). We detected no significant difference in iron or zinc content before and after treatment. The copper content was significantly reduced after treatment in both groups ( P < .05). The urine copper level was significantly increased after 1 week of treatment but decreased thereafter. Serum copper levels were significantly reduced after treatment ( P < .01). We detected no significant difference in transaminase level before and after treatment. Iron-deficiency anemia in 1 patient after 12 weeks' treatment was the only adverse reaction, and it was improved by the administration of an iron product. We noted no other overt adverse reactions. In patients with hepatocellular carcinoma, trientine hydrochloride therapy may significantly reduce copper content in liver tissue.

ASSESSMENT OF SERUM MATRIX METALLOPROTEINASES MMP-2 AND MMP-9 AFTER HUMAN LIVER TRANSPLANTATION: INCREASED SERUM MMP-9 LEVEL IN ACUTE REJECTION

Alterations in synthesis and breakdown of extracellular matrix components play a role in acute rejection after orthotopic liver transplantation (OLT). Matrix metalloproteinases (MMPs) are capable of degrading basement membranes and are involved in the process of tissue remodelling in inflammation and liver fibrosis. We examined MMP-2 and MMP-9 in serum of 33 patients before and during 1 year after OLT, in 60 controls as well as in some specimens of cirrhotic liver and control liver tissue. Serum MMP-2 levels before OLT were significantly higher compared with controls and decreased approximately 50% after OLT. Also, the MMP-2 content of cirrhotic liver specimens was significantly higher compared with normal liver. MMP-9 in serum and liver tissue of patients were similar to controls, but serum levels showed a peak at 1 week after OLT. At this time-point, total and active/inhibitor-complexed MMP-9 was significantly higher in patients with rejection (n=13) compared with those without rejection (n=20). The relative amount of MMP-9 in the active/inhibitor-complexed form did not differ between each group over time. Immunohistochemical staining at 1 week after OLT showed increased numbers of MMP-9-positive inflammatory cells in the portal triads of patients with rejection. Patients with acute allograft rejection have elevated serum levels of MMP-9 1 week after OLT, which was most likely derived from inflammatory cells. An increased MMP-2 serum level and liver tissue content was found in patients with cirrhosis, which decreased after OLT. These observations indicate active involvement of MMP-2 and -9 in end-stage liver disease and OLT.

A fatal overdose of the ergot derivative cabergoline

A 79-year-old woman, with Parkinson’s disease treated with cabergoline, was admitted to a hospital due to jaundice and weakness. She was found confused, absent minded, and died after 2 weeks. Autopsy showed an extrahepatic bile duct adenocarcinoma with spread to the gall bladder, the liver, and regional lymphnodes. While cleaning the hospital bed after her death, the nurses found several tablets hidden in the bed. Biological samples obtained at the autopsy were screened for common drugs and narcotics. Several drugs such as buprenorphine, codeine, paracetamol, and propranolol were detected in the blood at therapeutic levels. A method to determine cabergoline in whole blood and other forensic matrices was developed, and further investigations determined cabergoline concentrations in whole blood and liver tissue of 94 and 3100 μg/kg, respectively. The blood concentration was 100 times above the therapeutic level reported on cabergoline in plasma and in combination with her symptoms, suggest she took a fatal overdose of cabergoline.

A fatal overdose of the ergot derivative cabergoline

A 79-year-old woman, with Parkinson’s disease treated with cabergoline, was admitted to a hospital due to jaundice and weakness. She was found confused, absent minded, and died after 2 weeks. Autopsy showed an extrahepatic bile duct adenocarcinoma with spread to the gall bladder, the liver, and regional lymphnodes. While cleaning the hospital bed after her death, the nurses found several tablets hidden in the bed. Biological samples obtained at the autopsy were screened for common drugs and narcotics. Several drugs such as buprenorphine, codeine, paracetamol, and propranolol were detected in the blood at therapeutic levels. A method to determine cabergoline in whole blood and other forensic matrices was developed, and further investigations determined cabergoline concentrations in whole blood and liver tissue of 94 and 3100 μg/kg, respectively. The blood concentration was 100 times above the therapeutic level reported on cabergoline in plasma and in combination with her symptoms, suggest she took a fatal overdose of cabergoline.

Comparison of doxorubicin concentration profiles in radiofrequency-ablated rat livers from sustained- and dual-release PLGA millirods.

To evaluate and compare the local pharmacokinetics of doxorubicin in radiofrequency (rf)-ablated rat livers after interstitial delivery from sustained- and dual-release poly(D,L-lactide-co-glycolide) (PLGA) millirods. PLGA millirods with sustained- and dual-release kinetics (burst followed by sustained release) of doxorubicin were implanted in rf-ablated rat livers. Doxorubicin release kinetics in vivo were measured from explanted millirods by UV-Vis spectrophotometer over 8 days. Spatial distribution of doxorubicin in liver tissues was measured by fluorescence imaging. In the initial 24 h after millirod implantation, dual-release millirods released significantly more doxorubicin into liver tissues than the sustained millirods. Subsequently, both types of millirods provided comparable sustained-release kinetics over 8 days. With dual-release millirods, doxorubicin concentration and penetration distance in liver tissue increased more rapidly. To reach 30 microg/g doxorubicin concentration at the ablation boundary (targeted site of action), the time required was 6 days and 1.5 days for sustained- and dual-release millirods, respectively. Compared with sustained-release millirods, dual-release millirods provide a quick concentration elevation and sustaining of the drug concentration at the ablation boundary. Additionally, the steady-state drug concentration agrees well with model predictions based on previously determined transport parameters, which demonstrates the feasibility of rational design of drug formulations in polymer millirods.

DDT and metabolites residues in the southern bent-wing bat ( Miniopterus schreibersii bassanii) of south-eastern Australia

The southern bent-wing bat ( Miniopterus schreibersii bassanii) is an insectivorous, obligate cave dwelling species found in south-eastern South Australia and western Victoria, Australia. In recent times, the finger of blame for an apparent population decline at Bat Cave, Naracoorte (one of only two known maternity roosts for this species, the other being Starlight Cave, Warrnambool) has been pointed at pesticide use in the region, following the finding of organochlorine and organophosphate insecticide residues in bat guano. This study sampled juvenile southern bent-wing bats from Bat Cave and Starlight Cave, and determined DDT, DDD and DDE concentrations in liver, pectoral muscle, brain and back-depot fat tissues. DDT was detected in only three tissue samples (highest concentration, 126 μg kg −1 (wet weight) in back-depot fat), DDD was detected only in brain tissue (highest concentration, 115 μg kg −1 (wet weight)), but DDE was detected in most tissues (highest concentration, 24 200 μg kg −1 (wet weight) in back-depot fat). A minimum DDE body burden was estimated for each bat, and then for each sex at each site, from the data from all tissues sampled. The DDE body burdens estimated were highest in male bats from Starlight Cave (114 μg kg −1), then females from Starlight Cave (54.5 μg kg −1), and males from Bat Cave (53.2 μg kg −1). Female bats at Bat Cave contained the lowest estimated body burden (24.2 μg kg −1). Comparisons of DDE concentrations between the sexes showed that contamination was not statistically different within each maternity site. The different chemical concentrations observed in the Bat Cave and Starlight Cave bats is suggestive of different feeding locations, and perhaps an emerging population split, further threatening a species already at risk as a result of landscape scale changes to land use across their range.

Dietary supplementation of α‐tocopheryl acetate on α‐tocopherol levels in duck tissues and its influence on meat storage stability

SummaryThe effect of feeding three levels of α‐tocopheryl acetate on quality and stability of duck meat was studied. Day‐old white Peking ducklings (n = 75) were assigned to three dietary treatments (n = 25) 20 mg α‐tocopheryl acetate per kg feed (E20, control), 400 mg α‐tocopheryl acetate per kg feed (E400) and 1000 mg α‐tocopheryl acetate per kg feed (E1000). α‐Tocopherol concentrations in breast, thigh, liver and heart tissues were significantly (P &lt; 0.05) increased, in a dose‐dependent manner. Supplementation also enhanced oxidative stability of duck muscle. Breast muscle was more susceptible to lipid oxidation than thigh muscle for all groups studied, even though breast muscle contained higher α‐tocopherol levels than thigh muscle. These findings are significant because previous studies using chickens and turkeys showed that breast meat was always more stable than thigh meat and that thigh meat always had higher α‐tocopherol levels than breast meat. Supplementation with α‐tocopheryl acetate did not improve the colour stability of duck meat.

Pioglitazone treatment activates AMP-activated protein kinase in rat liver and adipose tissue in vivo

Thiazolidinediones have been shown to activate AMP-activated protein kinase activity in cultured cells. Whether they have a similar effect in vivo and if so whether it is physiologically relevant is not known. To assess these questions, we examined the effects of pioglitazone, administered orally to intact rats, on AMPK phosphorylation (AMPK-P) (a measure of its activation) and acetyl CoA carboxylase (ACC) activity and malonyl CoA concentration in rat liver and adipose tissue. In the first study, measurements were made in the Dahl-salt-sensitive rat (Dahl-S), a strain of Sprague–Dawley rat with endogenous hypertriglyceridemia and high levels of malonyl CoA that are restored to control values by pioglitazone. Treatment with pioglitazone (20 mg/kg bw/day for 3 weeks) did not significantly increase either P-AMPK or P-ACC (which varies inversely with ACC activity) in control rats. However, in the Dahl-S rats values for AMPK-P and ACC-P were 50% lower than in control rats and were doubled by pioglitazone treatment. In a second study, the effects of two weeks treatment with pioglitazone (3 mg/kg bw/day administered orally) were evaluated in Wistar rats. Under basal conditions (no manipulation of the animals), pioglitazone increased AMPK phosphorylation by twofold and decreased ACC activity and the concentration of malonyl CoA by 50% in liver. Following a euglycemic–hyperinsulinemic clamp (6 h), 50% decreases in AMPK and ACC phosphorylation (indicating an increase in its activity) and comparable increases in malonyl CoA concentration were observed in liver and adipose tissue. In both tissues, pre-treatment with pioglitazone prevented these changes. Where studied (in Wistar rats under basal conditions) treatment with pioglitazone decreased the concentration of ATP by 1/3 and increased the concentration of ADP and AMP in liver. The results indicate that treatment with pioglitazone can increase AMPK activity in rat liver and adipose tissue in a variety of circumstances. They also suggest that this activation of AMPK may be mediated by a change in cellular energy state. Whether these effects of pioglitazone contribute to its insulin-sensitizing and other actions in vivo remains to be determined.