The effect of goldthioglucose on peroxidative processes in mice.

Experiments were conducted to study the effect of goldthioglucose (GTG) upon the processes associated with lipid peroxidation. The glucose-6-phosphate dehydrogenase activity (G6PD; E.C. 1. 1.1.49) in red blood cells (RBC) and the amount of malonaldehyde precursors (MDA) per gram of brain, liver and kidney were determined. Adult mice received i.p. injections for three consecutive days of either saline (controls) or GTG dissolved in saline, in a dose of 0.10 mg.g(-1) or 0. 15 mg.g(-1) b.w. In mice receiving higher dose of GTG the G6PD activity was significantly increased (349.38+/-17.46 mU.10(-9) RBC compared to 258.2+/-14.46 mU.10(-9) RBC in control animals). The content of MDA precursors rose significantly from 4.8+/-0.81 micromol.g(-1) of the liver in controls to 8.12+/-1.41 micromol.g(-1) and 7.88+/-0.51 micromol.g(-1) and from 18.71+/-1.01 micromol.g(-1) of the kidneys in controls to 24.25+/-1.25 micromol.g(-1) and 24.88+/-1.7 micromol.g(-1) respectively. The GTG-induced higher levels of MDA precursors and increased G6PD activity in RBC corresponds to the rise in lipid peroxidation and its participation in producing the lesions after experimental and therapeutic use of gold-containing substances seems possible.

[Heavy metal poisoning in relation to glucose-6-phosphate dehydrogenase activity in sheep erythrocytes]. / Intoxikácia tazkými kovmi vo vztahu k aktivite glukóza-6-fosfát dehydrogenázy v erytrocytoch oviec.

Peroxidative lesions of cells and production of free radicals from endo- and exogenous reasons, eg. due to air pollution, can result in severe lesions of cells and subsequent pathological processes (Rieger, 1992; Robbins and Cotran, 1988). A pentose cycle plays an important role in the system of antioxidative protection: glucose-6-phosphate dehydrogenase (G-6-PD; EC 1.1.1.49) is its first enzyme. G-6-PD activity was evaluated in the erythrocytes of sheep kept in the region contaminated by heavy metals with mercury dominating among them, and in the same animals after administration of a feed mixture containing Hg, Pb Cd, Zn Cr, Cu, Fe and As (Fig. 1). Boehringer Mannheim test was used to determine the G-6-PD activity. There was no significant differences in the enzyme activity in the sheep from a contaminated region and in the animals outside the air-pollution region (control animals) before the applications of heavy metals started. The average value of G-6-PD activity was 13.96 +/- 0.94 mU.10 (-9) Ec in control animals and 14.39 +/- 1.49 mU.10 (-9) Ec in the animals from a contaminated region. After eight-day applications of heavy metals the G-6-PD activity increased statistically significantly to 18.71 +/- 2.45 mU.10 (-9) Ec; P < 0.01, and to 23.55 +/- 1.87 mU 10 (-9) Ec after 16 days of application; P < 0.001 (Fig. 2). An increase in G-6-PD activity after heavy metal applications is probably a compensation mechanism in the system of erythrocyte antioxidative protection due to higher peroxidation. The long term increased intake of heavy metals from polluted air did not lead to any rise of G-6-PD activity probably due to the lower dose of heavy metals and/or to adaptation of animal organisms to long run emission exposure. The results demonstrate that G-6-PD can be one of the biochemical indicators at organism load by heavy metals with mercury dominating among them.

[Concentration of free amino acids in the blood plasma of sheep with different amounts of nitrogen in the feed]. / Koncentrácia vol'ných aminokyselín v krvnej plazme oviec pri roznom príjme dusíka v krmive.

Trials were conducted with four adult sheep of the Merino breed, live weight 45 to 50 kg, fed two diets with different nitrogen levels (7.6 g nitrogen per day as protein or 24 g nitrogen per day with an addition of 17.4 g urea nitrogen to 7.6 g nitrogen as protein). The following findings were obtained: the concentration of free amino acids in blood plasma in the 9th, 12th, 15th, 18th and 22nd weeks from the beginning of feeding with both diets was lower, in most of the analyzed amino acids, three hours after feeding than before feeding. The results show that at an increased intake of urea nitrogen the concentration increases of the free amino acids lysine, serine, glutamic acid, glycine, valine and isoleucine before feeding. Three hours after feeding these differences are less pronounced. An increase is only recorded in the concentration of arginine, glutamic acid and glycine, whereas the concentration of alanine decreases.

Urease activity in the contents and tissues of the sheep, pig and chicken gastrointestinal apparatus.

Urease activity, expressed as mg N-NH3/g dry weight per 30 min at 25 degrees C, was determined in the various parts of the sheep, chicken and pig digestive apparatus. The results were as follows. Sheep: contents--rumen 1.25"/-0.09, reticulum 0.78+/-0.02, omasum 0.44+/-0.02, abomasum 0.002+/-0.001, duodenum 0.003+/-0.001, jejunum 0.18+/-0.03, ileum 0.42+/-0.03, caecum 1.34+/-0.11, colon 0.76+/-0.08, walls-rumen 0.88+/-0.16, reticulum 0.38+/-0.04, omasum 0.11+/-0.02, abomasum 0.01+/-0.002, ileum 0.092+/-0.01, caecum 0.14+/-0.03, colon 0.16+/-0.02. Chicken: contents--jejunum 0.028+/-0.009, ileum 0.043+/-0.013, caecum 0.17+/-0.03, colon and cloaca 0.04+/-0.013. Pigs: contents--jejunum 0.02+/-0.01, ileum 0.14+/-0.08, caecum 0.62+-0.12, colon 0.43+/-0.06. No urease activity was found in the walls of the digestive apparatus or the contents of the duodenum in chickens, or in the walls of the stomach and intestine and the contents of the duodenum in pigs. The results show that urease activity in the digestive apparatus of pigs and poultry is lower than in sheep. Inadequate urease activity in the digestive apparatus explains why chickens and pigs are significantly less capable than ruminants of utilizing urea nitrogen as a substitute for some of the protein in the diet.

[Passage of amino acids through the minimal wall in sheep]. / Priestup aminokyselín cez bachorovú stenu oviec.

Three sheep with a small isolated rumen (after Gridin et al., 1964) were studied for the passage of amino acids from the blood to the isolated rumen before feeding and 1, 2, 3, 4 and 5 hours after feeding. It was found that, on an average for all the time intervals mentioned above, the passage of glycine was the largest of all the amino acids studied (0.512 muMol per 100 ml), followed, in descending order, by lysine, alanine, glutamic acid, aspartic acid, serine, leucine, threonine, isoleucine, arginine, tyrosine, and phenylalanine (0.038 muMol per 100 ml). Before feeding and one hour after feeding, lysine shared the greatest proportion of all amino acids that had passed into the isolated rumen (0.565-0.43 muMol per 100 ml), followed, in descending order, by glycine, alanine, valine, aspartic acid, glutamic acid, leucine, serine, threonine, isoleucine, tyrosine, phenylalanine; arginine was, in this case, represented by the smallest proportion (0.042-0.030 muMol per 100 ml). It is inferred from the results that the amount of amino acids passing from the blood through the rumen wall changes with the time that has elapsed from feeding, and that before feeding this passage is more intensive than after feeding. These changes are held to be related with an increased passage of endogenous nitrogen to the rumen in the period of a relative deficiency of substances which are derived from the feed and are essential for maintaining homeostasis in the rumen.