Toxicity and genotoxicity in Astyanax bimaculatus (Characidae) induced by microcystins from a bloom of Microcystis spp

Studies of genotoxicity in fish caused by cyanobacterial microcystins can be useful both in determining the sensitivity of native species, as well as comparing exposure routes. The genotoxicity caused by the microcystins LR and LA from a bloom collected in a eutrophic lake, was revealed in the fish Astyanaxbimaculatus, a native species from South America. LC50 (72 h) was determined as 242.81 μg L (-1) and LD50 (72 h) as 49.19 μg kg (-1) bw. There was a significant increase of DNA damage in peripheral erythrocytes, following intraperitoneal injection (ip) with tested concentrations of 24.58 μg kg (-1) bw and 36.88 μg kg (-1) bw, as well as through body exposure to a concentration of 103.72 μg L (-1) . Micronucleus (MN) induction was observed after ip injections of 24.58 μg kg (-1) bw and 36.88 μg kg (-1) bw for 72 h, as well as following body exposure for 72 at 103.72 μg L (-1) . Thus, both exposure routes resulted in MN induction and DNA damage. Apoptosis-necrosis testing was carried out only by ip injection with concentrations of 24.58 μg kg (-1) bw and 36.88 μg kg- 1 bw. Exposure to microcystins at lower concentrations induced more apoptosis than necrosis in peripheral erythrocytes, whereas exposure at higher concentrations gave rise to both conditions. Thus, Astyanax bimaculatus can be considered as a species sensitive to the genotoxic effects caused by microcystins.     

Kinetics and inductive potency of 1,2,3,4,6,7,8-heptachlorodibenzo-p-dioxin (H7CDD) in rats

The kinetic properties and the inductive potency of 1,2,3,4,6,7,8-heptachlorodibenzo-p-dioxin (H7CDD) were studied in Wistar rats following subcutaneous (s.c.) injections. For assessing the dose-response, rats were treated with a single dose of 3. 10 or 30 microg H7CDD/kg body wt. Tissue concentrations and enzyme induction were measured 1, 2, and 3 weeks after treatment, and in the 30 microg/kg group additionally after 6, 20 and 57 weeks. Tissue concentrations increased dose-dependently from 3 to 30 microg/kg. Concentrations in liver were always higher than in adipose tissue, the concentration ratio: liver/adipose tissue varied between 32 and 67. The activity of (ethoxyresorufin O-deethylase) (EROD) in liver microsomes was clearly induced by H7CDD, reaching maximal induction three weeks after treatment. (3-fold at 3 microg/kg, 5-fold at 10 microg/kg and nearly 30-fold at 30 microg/kg). For assessing the time dependency, tissue levels and hepatic enzyme induction were monitored over a period of 57 weeks after a single s.c.-injection of 30 microg H7CDD/kg body wt. Hepatic concentrations of the congener remained rather constant from the 2nd to the 20th week after treatment (280 ng/g and 319 ng/g, respectively). In contrast, concentrations in adipose tissue and thymus increased 2-fold during this period, and 20 weeks after injection reached a maximum of 11 ng/g and 3 ng/g, respectively. Thereafter, the concentrations decreased and tissue levels of 91 ng/g (liver), 3 ng/g (adipose tissue) and 2 ng/g (thymus) were detected 57 weeks after treatment. The elimination half-life (t 1/2) calculated from our data was 140 days in liver and 130 days in adipose tissue. The reasonable explanation for the increase in tissue concentrations of H7CDD up to 20 weeks after treatment is the slow release of this congener from the subcutaneous injection site. Induction of hepatic EROD activity always closely followed changes in the hepatic concentrations of H7CDD, reaching a maximum 3 weeks after treatment and remaining at this level until the 20th week. Correlation analysis of hepatic H7CDD concentrations versus the extent of EROD induction indicated a linear relationship in a double-logarithmic plot. When compared with TCDD, the hepatic monooxygenase-inducing potency of H7CDD within the low dose range was found in the rat to be 170 to 440-times lower than that of TCDD. Measurement of 14C-caffeine demethylation, using a 14CO2 breath test, revealed a similar time course in vivo when compared with the microsomal EROD activity ex vivo.     

Comparison of the uptake and distribution of chromate in rats and mice

The purpose of this study was to evaluate species differences in tissue accumulation of chromium. Rats and mice were orally exposed to Cr(VI) (potassium chromate) via drinking water (8 mg/d/kg body wt for 4 or 8 wk) or by ip injection (0.3 and 0.8 mg/d/kg, for 4 or 14 d). Chromium concentrations were measured by atomic absorption spectrophotometry, and tissues were compared for exposure route and species differences. After oral exposure, irrespective of treatment duration, liver concentrations of chromium were three to four times higher in mice than rats, whereas kidney concentrations were about 50% lower. However, after ip injection, kidney and blood concentrations in rats were two- and four-fold, higher, respectively. Both rats and mice showed high values of Cr concentration in the bone. After single ip injection of Na₂ ⁵¹CrO₄; Cr concentrations were higher in the blood of rats than mice both after 24 and 72 h. Red blood cell concentrations of Cr were also greater in rats than mice by approximately threefold, whereas white blood cell Cr concentrations were higher in mice than rats. There was also a twofold greater binding of Cr/μmol of hemoglobin in rats compared to mice. These data indicate that species differences exist for Cr metabolism and that they differ with respect to the route of exposure. These results may be owing to species differences in the reduction of Cr and different binding of Cr to hemoglobin.     

DEVELOPMENTAL AND AGING CHANGES IN PROTEIN CONCENTRATION AND 2'',3''-CYCLIC NUCLEOSIDEMONOPHOSPHATE PHOSPHODIESTERASE ACTIVITY (EC 3.1.4.16) IN HUMAN CEREBRAL WHITE AND GRAY MATTER AND SPINAL CORD

Abstract— The concentration of protein as assayed by the Lowry method and the specific activity of 2′.3’-cyclic nucleosidemonophosphate phosphodiesterase (CNP), an enzyme characteristic of the myelin sheath, were determined in human CNS tissues obtained at autopsy from subjects ranging in age from 26 weeks gestation to 83 y. CNP activity in cerebral white matter samples was very low until approx 2 months of age when it increased rapidly, reaching near-adult levels by 2 y of age. CNP activity in adult (15–60 y) cerebral white matter was 8.1 ± 1.0 μmol/min/mg protein (mean ±s.d. ). The protein concentration of cerebral white matter increased from 64 mg/g wet tissue at 26 weeks gestation to adult levels (118.5 ± 10.0 mg/g wet tissue) by 16–18 months. CNP activity in cerebral gray matter was initially very low and showed only a small increase during development to adult values of approx 1.4 μmol/min/mg protein. In spinal cord, adult values (3.7 ± 0.56 μmol/min/mg protein) were found shortly after birth. The increase in CNP activity to near-adult values occurred earlier in cross-sections of cervical spinal cord than in cerebral white matter. The increase in spinal cord protein concentration showed a similar trend (adult values = 103.1 ± 9.5 mg/g wet tissue). The white matter protein concentration decreased significantly with age over the 15–83 y interval examined but the CNP specific activity in white matter did not. The protein concentration of the 61–83 y group was 8% lower than that of the 15–60 y group. The spinal cord protein concentration decreased significantly and the spinal cord CNP specific acitivity increased significantly with increasing time between death and sample freezing. The sex of the individual had no significant effect on any of the variables examined. The developmental curves obtained for these tissues are consistent with the hypothesis that CNP is an intrinsic myelin component in human CNS myelin. The marked increase in CNP activity in white matter coincides with the period of rapid myelin deposition as determined by other parameters. CNP activity may be useful as an index of myelination in human CNS tissues.     

Mannose-6-p and mannose-1-p in rat brain, kidney and liver.

The approximate concentrations of mannose-6-phosphate and mannose-1-phosphate in female rat brain, kidney and liver are respectively 51, 29 and 99 nmole/g (Man-6-P), and 13, 12, 15 nmol/g (Man-1-P). Intraperitoneal injection of mannose (20 nmol/kg body weight, 15, 30 or 60 min before sacrifice) raises the liver Man-6-P to 0.4 to 4.3 μmol/g and Man-1-P to 100 to 186 nmol/g.     

Experimental study on interactions between selenium and tin in mice

The organ distributions of tin and selenium, and their excretion into urine and feces, were determined in mice. There were four groups; (A) control, (B) Sn (5 μmol/kg/d) ip injection, (C) Se (5 μmol/kg/d) sc injection, and (D) Sn plus Se (5 μmol/kg/d, each). Animals received injections once a day for 12 consecutive days. The results were the following (1) Simultaneous injection of Sn and Se enhanced accumulation of both elements in the body, i.e., in group B, 14.1% of the total injected amount of Sn was excreted into urine and feces; in group C, 46.2% of total injected Se was excreted into urine and feces; in group D, 10.9% of total Sn and 37.5% of total Se were found in excreta. (2) Large amounts of Sn were found in bone, liver, spleen, and kidney in group B. When Se was administered jointly with Sn, the concentrations of Sn in bone and liver were suppressed, whereas those in spleen and pancreas were increased. (3) The effects of Se-injections at this dose on concentrations of Se in organs were small. (4) In plasma, chemical reduction of selenite by stannous chloride was not observed.     

Ethanol metabolism in guinea pig: In vivo ethanol elimination,alcohol dehydrogenase distribution,and subcellular localization of acetaldehyde dehydrogenase in liver

Guinea pig ethanol metabolism as well as distribution and activities of ethanol metabolizing enzymes were studied. Alcohol dehydrogenase (ADH; EC 1.1.1.1) is almost exclusively present in liver except for minor activities in the cecum. All other organ tissues tested (skeletal muscle, heart, brain, stomach, and testes) contained only negligible enzyme activities. In fed livers, ADH could only be demonstrated in the cytosolic fraction (2.94 μmol/g liver/min at 38 °C) and its apparent K_m value of 0.42 mm for ethanol as substrate is similar to the average K_m of the human enzymes. Acetaldehyde dehydrogenase (ALDH; EC 1.2.1.3) of guinea pig liver was measured at low (0.05 mm) and high (10 mm) acetaldehyde concentrations and its subcellular localization was found to be mainly mitochondrial. The total acetaldehyde activity in liver amounts to 3.56 μmol/g/ min. Fed and fasted animals showed similar zero-order alcohol elimination rates after intraperitoneal injection of 1.7 or 3.0 g ethanol/kg body wt. The ethanol elimination rate of fed animals after 1.7 g ethanol/kg body wt (2.59 μmol/g liver/min) was inhibited by 80% after intraperitoneal injection of 4-methylpyrazole. Average ethanol elimination rates in vivo after 1.7 g/kg ethanol commanded only 88% of the totally available ADH activity in fed guinea pig livers. Catalase (EC 1.11.1.6), an enzyme previously implicated in ethanol metabolism, is of 3.4-fold higher activity in guinea pig (10,400 U/g liver) than in rat livers (3,100 U/g liver), but 98% inhibition by 3-amino-1,2,4-triazole did not significantly alter ethanol elimination rates. After ethanol injection, fed and fasted guinea pigs reacted with prolonged hyperglycemia.     

Impaired renal function and aluminum metabolism

The consequences of renal functional impairment on aluminum (Al) excretion are not clear inasmuch as little is known about its glomerular filtration, tubular reabsorption, or secretion. The association of Al and the etiology of the dialysis encephalopathy syndrome and osteomalacia among patients with uremia suggests that renal functional impairment is a prerequisite for increased body Al stores. However, considerable evidence argues against the concept that tissue Al accumulation occurs as a simple consequence of renal failure. Many dialysis patients have high parathyroid hormone (PTH) concentrations that have been associated with neurologic abnormalities, bone disease, and anemia. The toxicity of PTH could be either direct or indirect by influencing the metabolism of potentially toxic substances such as Al. Our studies in normal rats suggest that gastrointestinal Al absorption and specific tissue burdens are enhanced by PTH, but not irreversibly, because the withdrawal of PTH resulted in Al egress. Dialysis patients are often treated with vitamin D analogs to prevent or control consequences of hyperparathyroidism and impaired 1,25-dihydroxycholecalciferol synthesis. Although some reports suggest that high bone Al in osteomalacia may be responsible for vitamin D resistance, our studies with normal rats suggest that its metabolites may also increase tissue Al burdens independent of PTH action. Thus, several factors operative in uremia other than impaired renal function may contribute to altered Al metabolism and, consequently, to its toxicity.     

Effects of oral aluminum on essential trace elements metabolism during pregnancy

The present study was conducted to assess in rats the effects of oral aluminum (Al) exposure on calcium (Ca), magnesium (Mg), manganese (Mn), copper (Cu), zinc (Zn), and iron (Fe) accumulation and urinary excretion. Three groups of plug-positive Sprague-Dawley (SD) rats were given by gavage 0, 200, and 400 mg/kg/d of Al(OH)₃ on gestational days 1–20. Three groups of nonpregnant female SD rats of the same age received Al(OH)₃ by gavage at the same doses for 20 consecutive days. At the end of the treatment period, 24-h urine samples were collected for analysis of Al and essential elements. Subsequently, all animals were sacrificed and samples of liver, bone, spleen, kidneys, and brain were removed for metal analyses. With some exceptions, the urinary amounts of Al, Mn, and Cu excreted by pregnant animals as well as the urinary levels of Al excreted by nonpregnant rats were higher in the Al-treated groups than in the respective control groups. Although higher Al levels were found in the liver of pregnant rats, the concentrations of Al in the brain of these animals were lower than those found in the same tissues of nonpregnant rats. With regard to the essential elements, tissue accumulation was most affected in pregnant than in nonpregnant animals. In pregnant rats, the hepatic and renal concentrations of Ca, Mg, Mn, Cu, Zn, and Fe, as well as the levels of Ca in bone, and the concentrations of Cu in brain were significantly higher in the Al-exposed groups than in the control group. According to the current results, oral Al exposure during pregnancy can produce significant changes in the tissue distribution of a number of essential elements.     

Selenium Deposition in Tissues and Eggs of Laying Hens Given Surplus of Selenium as Selenomethionine

Forty-eight Norwegian bred White Leghorn chickens were divided into 6 groups and fed a basal diet containing 0.30 mig Se/kg supplemented with 0, 0.1, 0.5, 1.0, 3.0 or 6.0 mg Se/ kg in the form of selenomethionine for 18 weeks. A supplement of only 0.1 mg Se/kg induced significantly higher selenium concentrations in breast muscle and eggs, particularly in the egg white. The increase of selenium in the tissue and egg was proportional to the amounts of selenomethionine added to the feed. In the group given 6.0 mg Se/kg, the selenium concentrations in all tissues and eggs analysed ranged from 4.8 to 7.3 μg Se/g. No signs of toxic effects were observed even at the highest intake of selenium. Excess supply of selenium as selenomethionine to chickens was shown to be more potent than sodium selenite in raising the selenium concentration in tissues and eggs. A supplementation up to 10 times the requirement did not increase the levels of selenium in poultry products to such a degree that they could be considered as a potential risk for human consumption.     

Effect of cadmium and aluminum intake on the antioxidant status and lipid peroxidation in rat tissues.

This work aimed to study the relationship between the accumulation of cadmium (Cd) or aluminum (Al) in certain tissues and the levels of lipid peroxides as well as tissue antioxidants. To carry out such investigations, CdCl2 was given to rats in two dose levels; 0.5 or 2.0 mg/kg i.p for 1 day or daily repeated doses for 2 weeks. Al was given as AlCl3 either in a single dose of 100 mg/kg or daily repeated doses of 20 mg/kg for 2 and 4 weeks. The measured parameters were tissue malondialdehyde (MDA, index of lipid peroxidation) and reduced glutathione (GSH) levels as well as the activities of glutathione peroxidase (GSH-PX), glutathione reductase (GSSG-R), and glucose-6-phosphate dehydrogenase (G-6-PDH) enzymes. Liver and kidney functions were assessed by measuring serum alanine aminotransferase (ALT) and alkaline phosphatase (ALP) activities as well as serum urea and creatinine concentrations. Cd and Al concentrations in the studied tissues were also measured. Results indicated that tissue Cd was significantly increased after administration of either Cd doses. After a single dose of 0.5 or 2.0 mg/kg CdCl2, the increase in tissue Cd levels were accompanied by an increase in MDA and a decrease in GSH levels. On the other hand, after repeated administration of Cd, tissue Cd accumulation was accompanied by increased hepatic and renal GSH levels with decrease in MDA content and a decrease in GSH-PX activity in liver. Liver function was affected at all dose regimens, whereas kidney function was affected only after 2 weeks administration of the higher dose. In Al treated rats, Al concentration was shown to be increased in liver much more than in brain. This was accompanied by a slight decrease in hepatic GSH level after 2 weeks and a decrease in GSH-PX activity after 4 weeks. Liver function was affected only after repeated injection of Al for 2 or 4 weeks. In general, Al administration exhibited safer pattern than Cd.     

The effects of selenium on oxidative stress biomarkers in the freshwater characid fish matrinxã, Brycon cephalus (Günther, 1869) exposed to organophosphate insecticide Folisuper 600 BR (methyl parathion)

Methyl parathion (MP), an organophosphate widely applied in agriculture and aquaculture, induces oxidative stress due to free radical generation and changes in the antioxidant defense system. The antioxidant roles of selenium (Se) were evaluated in Brycon cephalus exposed to 2 mg L(-1) of Folisuper 600 BR (MP commercial formulation - MPc, 600 g L(-1)) for 96 h. Catalase (CAT), glutathione peroxidase (GPx), superoxide dismutase (SOD), glutathione S-transferase (GST), reduced glutathione (GSH) and lipid peroxidation (LPO) levels in the gills, white muscle and liver were evaluated in fish fed on diets containing 0 or 1.5 mg Se kg(-1) for 8 weeks. In fish treated with a Se-free diet, the MPc exposure increased SOD and CAT activities in all tissues. However, the GPx activity decreased in white muscle and gills whereas no alterations were observed in the liver. MPc also increased GST activity in all tissues with a concurrent decrease in GSH levels. LPO values increased in white muscle and gills and did not change in liver after MPc exposure. A Se-supplemented diet reversed these findings, preventing increases in LPO levels and concurrent decreases in GPx activity in gills and white muscle. Similarly, GSH levels were maintained in all tissue after MPc exposure. These results suggest that dietary Se supplementation protects cells against MPc-induced oxidative stress.     

The efficacy of deferiprone on tissues aluminum removal and copper, zinc, manganese level in rabbits

The effect of 1,2-dimethyl-3-hydroxypyrid-4-one [deferiprone (DE)] on aluminum mobilization and elimination from tissues and serum as well as the influence on the excretion of trace elements, copper, zinc and manganese in rabbits was investigated. Sixteen New Zealand rabbits were randomly divided into three groups: control, Al-only and Al+DE. The Al-only and Al+DE animals received injections of Al2(SO43.18H2O 600 micromol Al/kg 5 days per week for 3 weeks. One week after the last Al injection the Al+DE rabbits were given deferiprone 750 micromol/kg/day intragastrically for 2 weeks. At the 42nd day the animals were sacrificed and the organs were taken and digested. Blood was taken from the ear artery three times (at the initiation of the experiment, before and after deferiprone administration). The aluminum and copper, zinc, manganese were determined by atomic absorption spectrophotometry. Our results showed that deferiprone could highly mobilize aluminum stores from tissues. At the end of experiment the aluminum contents of bone, kidney, liver and brain in Al+DE were significantly lower than that in Al-only rabbits. The copper, zinc, manganese contents were not affected by deferiprone administration.     

Selenium persistency and speciation in the tissues of lambs following the withdrawal of dietary high-dose selenium-enriched yeast

The objective was to determine the concentration of total selenium (Se) and the proportion of total Se comprised as selenomethionine (SeMet) and selenocysteine (SeCys) in post mortem tissues of lambs in the 6 weeks period following the withdrawal of a diet containing high-dose selenised yeast (HSY), derived from a specific strain of Saccharomyces cerevisae CNCM (Collection Nationale de Culture de Micro-organism) I-3060. Thirty Texel × Suffolk lambs used in this study had previously received diets (91 days) containing either HSY (6.30 mg Se per kg dry matter (DM)) or an unsupplemented control (C; 0.13 mg Se per kg DM). Following the period of supplementation, all lambs were then offered a complete pelleted diet, without additional Se (0.15 mg Se per kg DM), for 42 days. At enrolment and 21 and 42 days later, five lambs from each treatment were blood sampled, euthanased and samples of heart, liver, kidney and skeletal muscle (longissimus dorsi and psoas major) tissue were retained. Total Se concentration in whole blood and tissues was significantly (P < 0.001) higher in HSY lambs at all time points that had previously received long-term exposure to high dietary concentrations of SY. The distribution of total Se and the proportions of total Se comprised as SeMet and SeCys differed between tissues, treatment and time points. Total Se was greatest in HSY liver and kidney (22.64 and 18.96 mg Se per kg DM, respectively) and SeCys comprised the greatest proportion of total Se. Conversely, cardiac and skeletal muscle (longissimus dorsi and psoas major) tissues had lower total Se concentration (10.80, 7.02 and 7.82 mg Se per kg DM, respectively) and SeMet was the predominant selenised amino acid. Rates of Se clearance in HSY liver (307 μg Se per day) and kidney (238 μg Se per day) were higher compared with HSY cardiac tissue (120 μg Se per day) and skeletal muscle (20 μg Se per day). In conclusion, differences in Se clearance rates were different between tissue types, reflecting the relative metabolic activity of each tissue, and appear to be dependent on the proportions of total Se comprised as either SeMet or SeCys.     

犬传染性肝炎DNA疫苗安全性评价

目的研究犬传染性肝炎核酸疫苗pVAX1-CpG-Loop的安全性。方法 BALB/c小鼠随机分为4组,高剂量组(肌内注射每只200μg)、低剂量组(肌内注射每只100μg)、联合免疫组(肌内注射每只100μg,皮下注射50μg,滴鼻每只50μg)和PBS组,每两周免疫1次,共免疫3次。末次免疫后4周、6个月检测血常规和血液生化及对F1代的影响,用PCR和RT-PCR的方法检测DNA疫苗的生物学分布和存留时间,末次免疫后4周和6个月取脏器观察病理损伤。结果各剂量组的主要血液学检测指标、对F1代的影响差异无显著性。末次免疫后4周各剂量组AST明显高于对照组。DNA疫苗在注射部位可存留8周,其中高剂量组和低剂量组在肝、脾、肾和注射部位有分布,联合免疫组在肺组织也有分布。末次免疫后4周小鼠肝肾有淋巴细胞浸润,6个月后慢性炎症明显好转。结论由犬传染性肝炎病毒DNA疫苗引起的肝肾损伤是一过性的,并且pVAX1-CpG-Loop没有整合到宿主基因组,也没有传递给F1代。     

Aromatic acids derived from phenylalanine in the tissues of rats with experimentally induced phenylketonuria-like characteristics

1. Aromatic acids were extracted from brain and liver of rats with phenylketonuria-like characteristics produced by administration of phenylalanine, either alone or in combination with p-chlorophenylalanine. The metabolism of the aromatic acids in these tissues was measured by gas chromatography. 2. At 1h after an intraperitoneal injection of l-phenylalanine (1g/kg) in 23-day-old rats, the phenyl-lactate concentration was 2.2mug/g in the liver and 0.43mug/g in the brain, and the concentration of o-hydroxyphenylacetate was 0.26mug/g in the liver. 3. Phenylacetate concentrations in brain and liver were 0.26 and 0.14mug/g respectively. 4. Suckling rats produced phenyl-lactate less rapidly than weanling rats, but accumulated higher concentrations in longer-term experiments. 5. Intraperitoneal injections of phenyl-lactic acid showed that this compound could directly penetrate the blood-brain barrier, and could produce similar brain/liver ratios of phenyllactate to those found after phenylalanine injection. 6. Qualitative and quantitative similarities in urinary excretion of aromatic acids between the rats used in this study and human patients with uncontrolled phenylketonuria indicate that a patient with a circulating phenylalanine concentration of the order of those achieved in the experimental animal may have aromatic acid concentrations in brain and liver comparable with those found in the rats used in the present study.     

Comparison of ochratoxin A levels in edible pig tissues and in biological fluids after exposure to a contaminated diet

The aim of this study was to compare ochratoxin A (OTA) levels in pig tissues and biological fluids after animal exposure to contaminated diet (250 μg OTA/kg of feed) during 4 weeks of fattening. OTA concentrations were quantified using a validated immunoassay method (ELISA) and high-performance liquid chromatography with fluorescence detector (HPLC-FD). The highest mean OTA concentration in pig tissues was determined in kidneys of exposed animals (13.87?±?1.41 μg/kg), followed by lungs (10.47?±?1.97 μg/kg), liver (7.28?±?1.75 μg/kg), spleen (4.81?±?0.99 μg/kg), muscle tissue (4.72?±?0.86 μg/kg), fat tissue (4.11?±?0.88 μg/kg), heart (3.71?±?1.09 μg/kg), and brain (3.01?±?0.25 μg/kg). Furthermore, on the last day of exposure (day 28), significantly higher mean OTA levels were determined in urine (16.06?±?3.09 μg/L) in comparison to serum (4.77?±?1.57 μg/L) showing that OTA urine analysis could be a good marker to identify elevated levels of this contaminant in porcine tissues used for human consumption. This study gave guidelines for the most efficient OTA control in pig-derived biological materials that can be exercised at slaughterhouses.     

Effects of non-ortho-substituted polychlorinated biphenyls (congeners 77 and 126) on cytochrome p4501a and conjugation activities in rainbow trout (Oncorhynchus mykiss)

Immature rainbow trout (Oncorhynchus mykiss) in two separate experiments received a single intraperitoneal injection of 0.1, 1 and 5 mg/kg of either 3,3′,4,4′-tetra- or 3,3′,4,4′,5-pentachlorobiphenyl (IUPAC congeners 77 and 126, respectively). The experiments were run at water temperatures of 6 °C and 4 °C. Fish were killed 6 days after the injection. Biotransformation enzyme activities and cytochrome P4501A (CYP1A) amount and occurrence in different tissues were assayed. Congeners 77 and 126 strongly induced 7-ethoxyresorufin O-deethylase (EROD) and benzo(α)pyrene hydroxylase (AHH) activities in liver and kidney of rainbow trout. The induction of these cytochrome P4501A dependent monooxygenases was dose-related especially with congener 77 in the kidney. However, in the liver the highest dose of both congeners and in kidney the highest dose of congener 126 did not increase the catalytic monooxygenase activities as much as would have been expected based on the responses obtained with the lower doses. This may be because the monooxygenase activities already had attained their maximal induction capacity at 1 mg/kg dose of each congener. The PCB residues in liver were also determined and found to be highest after 5 mg/kg injections (610 μg/kg wet weight with congener 77 and 220 μg/kg with congener 126). When cytochrome P4501A protein content was measured, the induction of cytochrome P4501A was still on the increase even in those cases where catalytic activity failed to show any further induction. Immunohistochemical samples from liver, kidney and intestine showed cytochrome P4501A staining which strongly correlated with cytochrome P4501A in microsomes. Such observations suggest that the amount and occurrence of P4501A in the tissues can express the induction even when catalytic activities seem to be suppressed. With respect to enzymes mediating conjugation reactions, hepatic and renal UDP-glucuronosyltransferase (UDP-GT) activities showed elevated levels especially with the 1 and 5 mg/kg doses of both congeners. Glutathione S-transferase (GST) activities did not show such a clear trend. Congeners 77 and 126 preferentially affected the P4501A enzymes but to some extent also conjugation activities.     

High dietary vitamin A interferes with tissue α-tocopherol concentrations in fattening pigs: a study that examines administration and withdrawal times

This study aimed to assess the interaction between different dietary vitamin A (dVitA) levels and the same concentration of vitamin E (100 IU all-rac-α-tocopheryl acetate/kg feed) in growing-finishing pigs. In the first experiment, two fat sources × two dVitA levels (0 v. 100 000 IU) were used. The supplementation of 100 000 IU dVitA induced a range of 5.13 to 30.03 μg retinol/g liver, 62.78 to 426.88 μg retinol palmitate/g liver, and 0.60 to 1.96 μg retinol/g fat. Dietary fat did not affect retinol or retinyl palmitate deposition in pigs. The high concentration of dVitA produced lower fat and liver α-tocopherol concentrations, and increased susceptibility of muscle tissue to oxidation. A second experiment was carried out to study the retinol and α-tocopherol retention at different withdrawal times prior to slaughter (two dVitA levels; 0 v. 100 000 IU). A high dose of 100 000 IU vitamin A during a short 2-week period was enough to induce α-tocopherol depletion in liver and fat to a similar extent as when 100 000 IU were administered during the whole fattening. Muscle, fat and liver α-tocopherol concentrations were not affected by dVitA in the 1300-13 000 IU/kg range, but liver α-tocopherol concentration was higher when vitamin A was removed from the vitamin mix 5 weeks prior to slaughter (experiment 3).