Effect of glutathione depletion on apoptosis induced by thiram in Chinese hamster fibroblasts.

Fungicide thiram, which is also known as an inducer of allergic contact dermatitis (ACD), was used as a model compound of thiuram chemicals, and its cellular effects were investigated in cultured Chinese hamster V79 cells. The level of intracellular reduced glutathione (GSH), protein sulfhydryl (PSH) groups, protein carbonyls (PC), membrane lipid peroxidation reflected by enhanced thiobarbituric acid reactive substrates (TBARS) production, as well as apoptotic effect were determined. The apoptosis induction was determined by assessing DNA fragmentation by TUNEL, annexin V binding, and caspases activation assays, using fluorescent microscope or flow cytometry, respectively. The concentrations of thiram required to induce cellular GSH depletion (by 40-50%), protein, and membrane lipid peroxidation (2-fold, and 1.7-fold, respectively), as well as to induce apoptosis in V79 Chinese hamster fibroblasts without causing necrosis through cytotoxic effects were between 50-100 microM. To investigate the role of decreased GSH content in the toxicity of thiram, GSH level was modified prior to exposure. Pretreatment of V79 cells with N-acetyl-L-cysteine (NAC), a GSH biosynthesis precursor, prevented GSH decrease, PC and TBARS production, as well as caspases activation induced by thiram exposure. On the other hand, thiram effects were enhanced by the previous depletion of cellular GSH by L-buthionine-(S,R)-sulfoximine (BSO).

[Role of lipases in human metabolism]. / Rola lipaz w metabolizmie czlowieka.

Lipases play a crucial role in the metabolism of lipids in humans. These enzymes can be classified according to the location: located in the digestive juices (lingual lipase, gastric lipase and pancreatic lipase), located intracellularly (hormone-sensitive lipase and lysosomal acid lipase) and in the endothelial cells (lipoprotein lipase and hepatic lipase). In this review, we discuss the interrelationships of lipases, their structure in humans, how they are affected by hormones and the clinical aspects of their deficiency.

Changes in lipoprotein lipase activity and plasma liver lipids in thiram intoxicated rats.

Acute thiram (tetramethyl-bis-thiocarbamyl disulphide) poisoning of rat (a single dose of 50% LD50) caused decreased lipoprotein lipase (LPL) activity in adipose tissue, the greatest inhibition being observed at 72 h after administration of the pesticide. Simultaneously, the levels of total plasma cholesterol, triacylglycerols and the high density lipoprotein (HDL) cholesterol were increased. On repeated pesticide administration (5% LD50) decreased LPL activity was observed after 14 and 30 days of poisoning, whereas after 90 days the LPL activity was distinctly increased. The levels of total cholesterol (in all periods of poisoning) and HDL cholesterol (only after 30 days of poisoning) became increased. These changes were accompanied by decreased content of free fatty acids and increase of hepatic triacylglycerols. The changes observed in the lipoprotein lipase activity of thiram-poisoned rats correspond to the profiles of plasma lipoproteins typical of thyroid hypofunction.

Urine mutagenicity of petroleum plant workers.

The mutagenicity of urinary extracts from workers employed in a petroleum plant was analyzed by means of the plate test using S. typhimurium strains TA98 and TA100. Mean urinary mutagenic activities in TA98 were 2-14 times higher in the petroleum plant workers than in the control group. In TA100 these differences were even bigger, the mutagenicity in petroleum plant workers' urine being 3-42 times higher than in the control group. These results suggest that the environmental exposure of people to mutagenic substances is markedly increased in a petrochemical plant.

Effect of dichlorvos on the activity of lipoprotein lipase from adipose tissue, on plasma lipids and postheparin lipolytic plasma activity in rats.

The activity of lipoprotein lipase (LPL) from adipose tissue, the postheparin lipolytic activity (PHLA) in plasma, and the content of plasma lipoproteins were investigated in rats poisoned with dichlorvos (DDVP). Administration of a single dose (50% LD50) resulted in inhibition of LPL and PHLA; the greatest inhibition was observed at 24 and 48 h after administration of the posticide. The metabolism of serum lipoproteins was also altered; the content of triacylglycerols in very low density lipoproteins (VLDL) and low density lipoproteins (LDL) fractions was increased; the content of cholesterol was increased in VLDL and high density lipoproteins (HDL) fractions, and decreased in the LDL fraction. On repeated administration of small DDVP doses (5% LD50) the greatest changes were observed after 90 days of intoxication. The levels of all three determined lipoprotein fractions, as well as PHLA, were decreased. The LPL activity in adipose tissue was slightly raised. The results suggest that DDVP interferes with the metabolism of lipids.

Effect of two-week ethanol administration on lipoprotein lipase activity and blood serum lipids in the rat.

Influence of ethanol administration on adipose tissue lipoprotein lipase activity, serum lipids in the rat. Intoxication caused a decrease of lipoprotein lipase activity. In some animals a rise of serum high density lipoprotein cholesterol was observed which correlated positively with the content of cytochrome P-450 in the liver.

Kinetics and metabolism of theobromine in male rats.

On the basis of general pharmacological information (blood cells/plasma partition, plasma protein binding) and using HPLC as the principal analytical method, we investigated the kinetics and metabolism of theobromine (a caffeine metabolite) in male rats after a single dose and after a 2 week chronic application. Doses in both conditions varied between 1 and 100 mg/kg. In in vitro and in vivo the fraction of theobromine unbound to plasma proteins averaged 0.90 over a wide range of concentrations. No significant difference was found in the pharmacokinetic profile of the drug after acute or chronic treatment at different doses except for a reduction in the absorption rate constant as the dose increased. AUC values increased in proportion to the dose. The 2 treatment schedules were also similar as regards metabolism, at least 50% of the administered dose of theobromine being excreted unchanged, and 25% as 6-amino-5-[N-methyl- formylamino ]1-methyluracil. Only at the highest doses was there a tendency for theobromine to accumulate at the expense of its major metabolite (a uracil compound).

Plasma and platelet lipid composition and platelet aggregation by arachidonic acid in women on the pill.

Sensitivity to induction of platelet aggregation by arachidonic acid (AA) and changes in plasma and platelet polyunsaturated fatty acid distribution were studied in seven women before and after six months of oral contraceptive (OC) treatment with a combination of d-norgestrel (0.25 mg) and ethinylestradiol (0.05 mg). Special interest was focused on AA because certain metabolites of fatty acid induce platelets to aggregate and are considered to play a crucial role in thromboembolic processes. In plasma, AA concentrations increased slightly, but significantly, in both the free fatty acid (FFA) and phospholipid fractions; in platelets AA increased in the phospholipid and neutral lipid fractions. The threshold aggregating concentration (TAC) of AA was significantly reduced in platelets of women after six months of OC treatment (0.65 +/- 0.08 versus 0.30 +/- 0.04 mM). This suggests that changes in platelet fatty acid composition may be associated with in vitro changes in platelet sensitivity to AA. Such changes may contribute to the thrombotic tendency associated with OC treatment.

PIP: Sensitivity to induction of platelet aggregation by (AA) arachidonic acid and changes in plasma and platelet polyunsaturated fatty acid distribution were studied in 7 women before and after 6 months of (OC) oral contraceptive treatment with a combination of d-norgestrel (0.25 mg) and ethinyl estradiol (0.05 mg). Special interest was focused on AA because certain metabolites of this fatty acid induce platelets to aggregate and are considered to play a crucial role in thromboembolic processes. In plasma, AA concentrations increased slightly, but significantly, in both the free fatty acid and phospholipid fractions; in platelets AA increased in the phospholipid and neutral lipid fractions. The threshold aggregating concentration of AA was signifcantly reduced in platelets of women after 6 months of OC treatment (0.65 + or - 0.08 versus 0.30 + or -0.04 mM). This suggests that changes in platelet fatty acid composition may be associated with in vitro changes in platelet sensitivity to AA. Such changes may contribute to the thrombotic tendency associated with OC treatment.