Quality of organically and conventionally grown potatoes: four-year study of micronutrients, metals, secondary metabolites, enzymic browning and organoleptic properties.

The quality of potatoes from organic and conventional farming was investigated in this study. Tubers of eight potato varieties, organically and conventionally produced at one or two geographical sites in controlled field trials, were collected in four consecutive harvests from 1996-1999. The parameters analysed included nitrate, trace elements (As, Cd, Co, Cu, Fe, Hg, Mn, Ni, Pb, Se, Zn), vitamin C, potato glycoalkaloids, as well as chlorogenic acid, polyphenol oxidase and rate of tuber enzymic browning. The results indicated lower nitrate content and higher vitamin C and chlorogenic acid content to be the parameters most consistently differentiating organically from conventionally produced potatoes. Elevated concentrations of glycoalkaloids were also observed throughout the experiments in some potato varieties grown in organic farming systems. Principal component analysis (PCA) of the analytical and other data using three PCs confirmed a good separation between the organically and conventionally produced potatoes when studied in single crop years. However, score-plots (objects) and loading-plots (variables) of pooled results from the consecutive harvests showed that between the years' changes and also variety as well as geographical variations are equally or more important factors determining the quality of potatoes than the farming system. Further studies of various marker compounds of potato quality related to the organic or conventional farming systems should be performed before unbiased information can be given to the consumers.

Toxicological studies of the false morel (Gyromitra esculenta): embryotoxicity of monomethylhydrazine in the rat.

The embryotoxic and teratogenic potential of monomethylhydrazine (MMH), a toxic component of the widely consumed false morel (Gyromitra esculenta), was studied in rat. Groups of pregnant Sprague-Dawley rats received MMH as a constant i.v. infusion via implanted osmotic minipumps (1.2, 3.0, 4.2, 6.0, 9.0 or 13.2 mg MMH/kg bw/day) on days 6-13 of pregnancy, or as a single intragastric bolus (1 mg MMH/kg/bw or 5 mg MMH/kg/bw) on day 6 of pregnancy. Controls received corresponding amounts of saline. The average maternal serum concentrations, measured during the infusion treatment with a sensitive HPLC method, ranged from 0.072 micrograms MMH/ml (lowest dose) to 0.60 microgram MMH/ml (highest dose). The average serum levels measured 45 min after the intragastric application (peak levels) were 0.28 microgram MMH/ml and 1.6 microgram MMH/ml, respectively. Serum concentrations of MMH corresponding to those measured in the lower dose groups in this study were seen in pilot studies after a single mushroom meal in human volunteers. A dose-dependent, statistically significant increase in the number of resorptions was seen in all but the lowest dose group after the infusion of MMH. In addition, except for the two lowest doses, there was a dramatic, dose-dependent decrease in the pregnancy rate as compared to controls, with no pregnancies occurring at the two highest dose level groups. The decreased pregnancy rate was probably due to preimplantation loss which was shown to occur after a single intragastric bolus dose of MMH (5 mg/kg bw).(ABSTRACT TRUNCATED AT 250 WORDS)

Studies of embryotoxicity and the incidence of external malformations after continuous intravenous infusion of alpha-chaconine in pregnant rats.

Embryotoxicity and effects on the incidence of external malformations of the major potato glycoalkaloid alpha-chaconine (alpha-cha) were studied in rats. Pregnant Sprague-Dawley rats (n = 17) were given a continuous intravenous infusion of alpha-cha via implanted osmotic minipumps (1.7 mg/kg/day), to maintain a stable blood concentration on days 6-13 of gestation. Control animals received physiological saline solution or were left untreated, respectively. Blood serum levels of alpha-cha were monitored at selected time intervals during the treatment using a specific HPLC method. The foetal body weights and the number of resorbed or dead foetuses per litter in the alpha-cha treated group were not significantly different from the control groups. No case of malformation was detected among 143 foetuses inspected in the treated group. The average maternal blood serum concentration of alpha-cha measured during the experiment was 340 ng/ml. This is more than 20 times the average peak serum level previously reported for human volunteers after intake of potatoes with a total glycoalkaloid content at the upper safe limit for acute adverse effects. The results support the view that potato glycoalkaloids, at levels normally found in potatoes, do not present a risk for teratogenicity in humans.

Determination of potato glycoalkaloids and their aglycone in blood serum by high-performance liquid chromatography. Application to pharmacokinetic studies in humans.

The development of a high-performance liquid chromatography (HPLC) method for the separation and quantification of potato glycoalkaloids and their aglycone solanidine in blood serum is reported. High selectivity was obtained by using solid-phase extraction followed by off-line dual-column HPLC. Injections were made via a sample enrichment column to achieve maximum sensitivity in the assay. The potato alkaloids in the HPLC effluents were detected by ultraviolet absorption at 200 nm. The detection limits were estimated to be 0.3 ng/ml of serum for each of the alkaloids. The method was used to study the pharmacokinetics of potato glycoalkaloids in humans. alpha-Solanine and alpha-chaconine were detected in all blood serum samples collected from seven volunteers 1-25 h after a meal of potatoes. Solanidine was detected in some samples, but there were no traces of the mono- or diglycosides. The average apparent biological half-lives for alpha-solanine and alpha-chaconine were 11 and 19 h, respectively.

Effects of dietary sodium selenite supplementation on salicylate-induced embryo- and fetotoxicity in the rat.

The effects of dietary supplementation with sodium selenite (3.0 or 4.5 ppm Se) for 8 weeks prior to and throughout gestation on sodium salicylate induced embryo- and fetotoxicity (resorptions, fetal deaths, malformations, fetal weight reduction) have been studied in the rat. Salicylate was administered either as daily intragastric bolus doses of 250 mg/kg on gestation days 6-13 (maternal peak and trough salicylate levels of 222-120 micrograms/ml whole-blood) or via constant rate intravenous infusion of 150 mg/kg/day on the same gestation days via implanted osmotic minipumps (stable average maternal blood salicylate level of 120 micrograms/ml = human antirheumatic concentration). Both gavage and infusion of salicylate resulted in an increase of resorptions and fetal deaths as well as a decrease of fetal body weights. Gavage with salicylate also produced about 50% malformed fetuses. Selenite did not protect against the embryotoxic effects of salicylate administered as intragastric bolus doses. However, selenite was found to significantly increase fetal survival rate in the infusion experiment, although it did not counteract the decrease of fetal body weight. In animals fed selenite only, no negative effects on fetal body development were noted. The protective effect of selenite against salicylate induced embryotoxicity is difficult to explain, since very little is known about the mechanisms of salicylate embryotoxicity and the biological effects of selenium. However, an interaction between selenium, via glutathione peroxidase, and salicylate at the level of prostaglandin synthesis could be possible.

Tissue accumulation of lipoprotein associated toxaphene in normo- and hypolipidemic mice.

Normo- and hypolipidemic mice were given a single i.v. injection of 14C-toxaphene associated with low density lipoprotein (LDL), high density lipoprotein (HDL) or dimethyl sulfoxide (DMSO). The tissue distribution of radioactivity was studied 20 min and 4 h after the application. In the normolipidemic mice at 20 min postinjection there was high uptake of the 14C-toxaphene preparations in the liver and adrenals followed after 4 h by a redistribution to the adipose tissues. In the hypolipidemic mice, proportionally less label accumulated initially in the liver and adrenals while more radioactivity was seen in the kidneys and heart. The radioactivity then redistributed to the liver with a very small uptake in the adipose tissue compared to the normolipidemic mice after 4 h. The results indicate that changes in the lipid pattern, e.g. hypolipidemic conditions, may influence the tissue distribution of lipophilic xenobiotics.

Distribution of toxaphene, DDT, and PCB among lipoprotein fractions in rat and human plasma.

The distribution of 14C-toxaphene, 14C-DDT, and 14C-PCB among lipoprotein fractions was studied in vitro and in vivo using rat and human plasma. The association of these substances with rat plasma fractions was similar in both in vitro and in vivo experiments. Thirty-seven to fifty-two per cent of the total radioactivity was associated with the cholesterol-rich high density lipoproteins (HDL2, d = 1.075-1.21 g/ml) and 18-52% was recovered in the albumin-rich bottom fraction (BF, d greater than 1.21 g/ml). A time-dependent redistribution of the radioactivity from the lipoprotein fractions to the BF was also observed in the in vivo studies. In human plasma, the distribution of the three compounds was different and uncorrelated to the cholesterol level of the individual lipoprotein fractions. Toxaphene was almost equally distributed between BF (d greater than 1.21 ml), HDL (d = 1.063-1.21 g/ml) and low density lipoproteins (LDL, d = 1.006-1.063 g/ml) (26%, 27% and 29%, respectively), while only 18% appeared in the very low density lipoprotein (VLDL, d less than 1.006) fraction. In contrast, a large proportion of DDT and PCB radioactivity was recovered in the BF (52% and 62%, respectively) while only 38-48% was present in lipoprotein fractions. The complex nature of the interaction between xenobiotics and plasma lipoproteins is discussed.

Ivermectin residues in the edible tissues of swine and cattle: effect of cooking and toxicological evaluation.

Young male pigs (25-40 kg bw) were treated experimentally with a single 0.4 mg/kg bw, s.c. dose of ivermectin (Ivomec vet. inj., MSD). The disappearance of the drug from the edible tissues 7-21 days after treatment was studied using a sensitive high-performance liquid chromatographic method. The highest residue levels were found at the injection site (up to 59 and 2.6 mg/kg 7 and 14 days post-injection, respectively). Among the other tissues studied, the residue levels 7 days post-injection showed the following order: liver (less than or equal to 50 micrograms/kg) greater than kidney (less than or equal to 25 micrograms/kg) greater than muscle (less than or equal to 20 micrograms/kg). After 21 days only traces of ivermectin (less than or equal to 2 micrograms/kg) could be detected in the muscle and other edible tissues, including the injection site. Similar residue concentrations were found in slaughterhouse material from sows therapeutically treated with ivermectin for parasite infestation. An ordinary culinary preparation of the minced beef muscle from a bull treated with ivermectin resulted in a 45% (boiling) or 50% (frying) decrease in the drug residue. Based on the known toxic effects of the drug and the results of the present and other residue studies, the suggested withdrawal time for Ivomec in edible tissues of swine and cattle is 21 and 28 days, respectively.

Effects of dietary selenium compounds on benzo (a)-pyrene-induced forestomach tumours and whole-blood glutathione peroxidase activities in C3H mice.

Selenium (Se) compounds have shown an inhibitory effect on chemically induced tumours in several laboratory models and there is an inverse epidemiological relationship between Se status and certain types of cancer. Little is known about the influence of Se on the development of stomach cancer. Three different forms of dietary Se, selenomethionine, sodium selenite, and high-selenium yeast were investigated as possible inhibitors of benzo(a)pyrene-induced forestomach tumours in mice. The effects of sodium selenite in combination with vitamin E, and of Se-deficiency were also studied. None of the dietary modifications had any effect on tumour incidence or number. Marked elevations of whole-blood glutathione peroxidase (GSH-Px) activities were observed in animals supplemented with all Se-compounds. High-selenium yeast caused the largest increase of GSH-Px activity followed by sodium selenite and selenomethionine. The results indicate that the inhibitory effect of Se on carcinogenesis may be specific with respect to organ site or tumour cell examined.

A muscarinic receptor type in human lymphocytes: a comparison of 3H-QNB binding to intact lymphocytes and lysed lymphocyte membranes.

Human blood lymphocytes from normal blood donors exhibited specific binding of the muscarinic antagonist 3H-quinuclidinyl benzilate (3H-QNB). The 3H-QNB binding to intact viable lymphocytes as well as to lysed lymphocyte membranes "P2" was saturable and displaceable by both muscarinic agonists and antagonists. For the lysed lymphocyte membranes "P2" a single binding site with a Bmax of 109 pmol/g protein and a Kd of 15 nM was obtained. Intact viable lymphocytes also showed one binding site with a Kd of 24 nM and a Bmax of 1556 pmol/g protein. The higher Bmax value might be explained in terms of uptake of the ligand when using intact cells or through loss of binding sites when using lysed lymphocyte membranes "P2". IC50 values were lower by a factor of 10(2) for atropine and scopolamine and by 10(4) for pirenzepine when lysed lymphocyte membranes "P2" were used instead of intact viable lymphocytes.

Dietary citric acid enhances absorption of aluminum in antacids.

Ten healthy men ingested, twice daily between meals, during each of the seven-day experimental periods: (a) citric acid (as lemon juice), (b) Al(OH)3, or (c) Al(OH)3 + citric acid. Whole blood sampled after each dietary period was analyzed electrothermally after digestion with nitric acid. Moderate, but significant, increases in mean Al concentrations as compared with pretreatment values [5 (SD 3) micrograms of Al per liter] were seen after ingestion of either citric acid or Al(OH)3: 9 (SD 4) and 12 (SD 3) micrograms/L, respectively. Ingestion of both Al(OH)3 and citric acid resulted in a more pronounced, highly significant (p less than 0.001) increase in Al concentrations, to 23 (SD 2) micrograms Al/L, probably owing to formation and absorption of Al-citrate complexes.

The tissue localization of m-AMSA and its effect on thymidine incorporation in various tissues in vivo.

The distribution of 14C-labelled m-AMSA was studied in rats and pigmented mice using whole body autoradiography. The agent rapidly disappeared from the blood, accumulating in significant amounts in large parenchymal organs, certain endocrine tissues, and the retina of the pigmented mouse eye. The hemopoietic and lymphoid tissues showed a moderate uptake of radioactivity with the highest concentration observed in the thymus. The autoradiograms indicated a rapid excretion of radioactivity via the liver, kidney and the glandular part of the gastric mucosa. The distribution pattern of label from 14C-m-AMSA remained unaffected by pretreatment of animals with high dose (500 mg kg-1 b.w.) of cytosine arabinoside. Injection of unlabelled m-AMSA (7 mg kg-1 b.w.) to growing rats 24 h before sacrifice resulted in a highly significant (P less than 0.001) inhibition of 3H-thymidine incorporation into the DNA of thymus and spleen. A less pronounced reduction was observed in the kidney, adrenal, lung and testes. The thymidine incorporation into the DNA of bone marrow was markedly suppressed when calculated per dry weight, but increased when related to the DNA content, suggesting early regeneration of the remaining cells. In contrast, no significant effects were observed on the DNA synthesis in small intestine and liver.

Effects of dietary supplementation with selenomethionine on the teratogenic effect of ionizing radiation in mice.

Female C3H mice were fed a standard pellet diet (containing 0.2 ppm Se and 30 ppm vit. E) or the same diet supplemented with 0.8 ppm (low dose) or 3.4 ppm (high dose) of selenomethionine for 10 weeks. After mating with males receiving the standard diet the mice were subjected, on the 9th day of pregnancy, to whole body roentgen irradiation of 1.75 Gy. On day 18 of gestation the frequency of resorptions, mortality and the incidence of fetal malformations were studied. Supplementation with Se-methionine resulted in a significant but dose-independent decrease (p less than 0.005) of the number of malformed fetuses from 62 per cent in the irradiated controls to 47 per cent in the low Se-group and high Se-group, respectively. In addition, the number of total malformations as well as fetal resorptions were significantly decreased in a dose-independent manner in the supplemented groups. The decrease in fetal malformations occurred proportionally for all the major malformations observed, i.e. short or kinked tail, rib and vertebral malformations, coloboma and deformation of retina and iris. Glutathione peroxidase activity in whole blood of Se-methionine fed mice was significantly increased. Thus, Se-rich diet may result in scavenaging of radiation-induced hydroperoxides.

Influence of dietary factors on aluminium absorption and retention in the brain and bone of rats.

Young adult male Sprague-Dawley rats were treated by gavage for 10 weeks (3-times weekly) with aluminium 100 mg/kg b.wt. in the form of Al-hydroxide (Novalucol), Al-citrate, Al-hydroxide together with citric acid or with tap water (controls). Male rats aged 13 months were gavaged for 11 weeks 3-times a weak with black currant soup (0.8 ml/kg b.wt.) stored 19 days in either aluminium or stainless steel saucepans. The brain cortex, bone and blood (young adults only) of each rat were analysed for Al using graphite furnace atomic absorption spectroscopy. The rats treated with Al-citrate and in particular rats treated with Al-hydroxide + citric acid showed a significant increase of Al concentrations in all the tissues studied. In the latter group the mean Al concentrations were elevated at 0.039 micrograms Al/g wet weight (controls 0.005 micrograms/g) 0.092 micrograms/g (0.016 micrograms/g) and 26.6 micrograms/g (0.22 micrograms/g) in the blood, brain and bone, respectively. After treatment with Al-hydroxide alone only the bone showed a moderate increase of Al-concentration. No significant differences were found in the brain and bone Al levels of the rats given fruit soup from aluminium saucepans (containing 17 mg Al/l) or stainless steel saucepans (0.4 mg Al/l).

Toxaphene: accumulation in the adrenal cortex and effect on ACTH-stimulated corticosteroid synthesis in the rat.

Uptake and distribution of [14C]toxaphene was studied in the adrenals of rats using whole-body autoradiography. An accumulation of radioactivity was seen in the adrenal cortex (zona fasciculata) 1-24 h after a single gavage of [14C]toxaphene (16 mg/kg b.w.). In in vitro studies toxaphene was found to inhibit ACTH-stimulated corticosterone synthesis in the cultured rat adrenocortical cells (IC50 2.8 X 10(-5) M). Moderate but significant inhibition (P less than 0.001) of ACTH-stimulated corticosterone synthesis was also observed in the adrenocortical cells isolated from rats after a prolonged exposure (5 weeks) to low levels (1.2 ppm) of toxaphene in feed. The results indicate a direct adrenotoxic effect of toxaphene.

Uptake of radiolabelled alpha-linolenic, arachidonic and oleic acid in tissues of normal and essential fatty acid-deficient rats--an autoradiographic study.

Rats fed diets with a low (0.3% of total energy) or normal (3%) essential fatty acid (EFA) content were injected intravenously with a single dose of 14C-labelled alpha-linolenic, arachidonic or oleic acid and the distribution of radioactivity in the tissues was compared 5 min, 1 h and 18 h after the application using whole-body autoradiography. The highest levels of labelling with all fatty acids were observed in the liver, brown fat and adrenal cortex. Specific for arachidonic acid was a high and consistent concentration of radioactivity in the myocardium at all times and for oleic acid in the white fat after 18 h. The tissue uptake of arachidonic acid was similar in both dietary groups, whereas a higher accumulation of alpha-linolenic was seen in most of the tissues in the low EFA group after 18 h compared to the normal EFA group. The uptake of oleic acid was higher in some tissues in the low EFA than in the normal EFA group after 1 h, but after 18 h these differences had disappeared almost completely.

Effects of DDT on muscarine- and nicotine-like binding sites in CNS of immature and adult mice.

Immature (10 days of age) and adult (60 days of age) mice were given a single peroral administration of 0.5 mg p,p'-DDT/kg body wt. or a fat emulsion vehicle. The mice were killed 24 h or 7 days post-treatment and the muscarine- and nicotine-like binding sites were measured in the cerebral cortex and in the cerebellum using [3H]quinuclidinyl benzilate ([3H]QNB) and [3H]alpha-bungarotoxin ([3H]alpha-BTX), respectively, as ligands. A significant decrease in the [3H]QNB binding to the muscarine-like receptors in the cerebral cortex was seen in the 1,1,1-trichloro-2,2-bis(p-chlorophenyl)ethane (DDT)-treated adults after 7 days. The effects on the muscarine-like receptors appeared to be different in the immature mice compared to the adults, showing an increase between 24 h and 7 days post-treatment in the immature and a decrease in the adults. No change was seen on the nicotine-like receptors.

Aluminium concentrations in the brain and bone of rats fed citric acid, aluminium citrate or aluminium hydroxide.

Male Sprague-Dawley rats were treated daily by gastric intubation (6 days/wk) with 100 mg aluminium/kg body weight in the form of aluminium hydroxide (9 wk) or aluminium citrate (4 wk), with citric acid (4 wk) or with tap-water (control, 9 wk). Young adult and aged Wistar rats were treated with 100 mg aluminium/kg body weight as aluminium hydroxide or with carboxymethylcellulose (vehicle controls). The cerebral cortex, hippocampus, cerebellum and samples of bone from each rat were analysed for aluminium, after digestion with nitric acid, using graphite furnace atomic absorption spectroscopy. The mean aluminium concentrations detected in the control Sprague-Dawley rats were 0.013-0.022 microgram/g wet weight in the various brain regions and 0.355 microgram/g in the bone. No significant increase in tissue aluminium concentrations was observed in Sprague-Dawley or Wistar rats after treatment with aluminium hydroxide. However the rats treated with aluminium citrate showed significantly increased concentrations of aluminium in all the brain regions studied (0.057-0.121 microgram A1/g) and in the bone (12.9 micrograms A1/g). Elevated aluminium concentrations in the cerebral cortex and bone were also observed in the animals fed citric acid suggesting possible absorption of the citrate chelate presumably formed with the traces of aluminium present in the diet.

Disposition of some sulphur-containing hexachlorobenzene (HCB) metabolites: affinity of methylsulphonylpentachlorobenzene for the gray matter of brain, the lungs and the adrenal zona reticularis.

The distribution of methylsulphonylpentachloro-[14C]benzene (I), methylthiopentachloro-[14C]benzene (II), 1,4-bis(methylthio)tetrachloro-[14C]benzene (III) and 1,2,4-tris(methylthio)trichloro[14C]benzene (IV) was studied after intravenous injection in mice. The administration of I resulted in a rapid and selective accumulation of radioactivity in the gray matter of the brain, the lung and the zona reticularis of the adrenal cortex. In mice pretreated with metyrapone, or with high dose of unlabelled I, the radioactivity in the tissues was increased, whereas pretreatment with diethyl maleate did not change the disposition of I. In mice injected with II-IV no site of selective accumulation in the tissues was observed. Similarly to I, compounds II-IV were rapidly excreted in bile/faeces and urine. It is proposed that the sulphone group is essential for the high affinity of I for the brain, lung and adrenal cortex.