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Biomedical subjects

T Motyl

Publications and source records attributed to T Motyl.

At least 55 records · Page 3Linked to original sources
PubMed1991

Variability of orotic acid concentration in cow's milk.

The average concentration of orotic acid in the milk of 412 Black and White bred cows from four Polish provinces was 0.618 +/- 0.233 mmol/l. There was no correlation between milk yield and concentration of orotic acid. A higher concentration of this pyrimidine in younger cows, and its increase during development of lactation was noted. The yearly pattern of orotic acid in milk and urine of four low-, and four high-orotate cows was examined. In spite of high average differences in milk orotate (0.397 and 0.813 mmol/l) no significant differences in urinary orotate (20.96 and 21.90 mumol/mmol creatinine) were observed. In both groups the lowest milk orotate level occurred in early lactation. The orotic acid content (mmol/l) in commercial milk products was as follows: skim milk--0.783; evaporated milk--0.538; cream 12% fat--0.367; buttermilk--0.449; yogurt--0.331; kefir--0.341; sour milk 2% fat--0.360; dried skim milk--1.042; Bebiko I (infant formula)--0.650. Leukemia led to the elevation (0.845 mmol/l), whereas mastitis to the depression (0.124 mmol/l) of milk orotic acid level.

Animals↗
PubMed1988

The relationship between urea and pyrimidine de novo synthesis in ruminant liver.

The influence of ammonia and inhibition of the urea cycle by norvaline on orotic acid synthesis in five Polish Merino ewes was investigated. The sheep were exposed to 60 min of successive infusions of 0.9% NaCl, NH4Cl (20 mumol kg-1 min-1), and NH4Cl with DL-norvaline (10 mumol kg-1 min-1) solutions administered to the mesenteric vein. The average rate of orotic acid output, urea output and ammonia uptake in the liver in control conditions (infusion of 0.9% NaCl) was: 1.09 nmol g-1 min-1, 0.97 mumol g-1 min-1 and 0.94 mumol g-1 min-1, respectively. Ammonia significantly stimulated the orotic acid output, urea output and ammonia uptake. At the same time liver uptake of glutamic acid, alanine and glycine increased. Norvaline as a competitive inhibitor of ornithine transcarbamylase depressed citrulline release and urea output in the liver, and elevated, although not significantly, the orotic acid output. It was concluded that ammonia stimulates the de novo synthesis of pyrimidine in the sheep liver but the participation in this effect of carbamyl phosphate generated in the urea cycle is limited.

Amino Acids↗
PubMed1986

The orotic acid concentration in the blood, milk, and urine of dairy cows fed with urea supplemented diet.

The experiment was performed on 4 cows Black and White, 550-650 kg of body weight, before and during 100 days after parturition. Two cows were fed with control and the next two with urea supplemented diet (urea-N constituting about 20% of total N in ration, 13% c.p. in DM). In cows fed with urea supplemented diet the considerable but unequal increase of urinary orotic acid excretion (particularly evident in first 30 days of lactation) was observed. There was however no influence of urea ration on the level of orotic acid in milk. The average orotic acid level in blood plasma (1.14 +/- 0.71 mumol X l-1 and 0.94 +/- 0.22 mumol X l-1 for control and urea fed cow respectively) established 0.01 and 0.001 of the average orotic acid concentration in urine and milk, respectively. Feeding with urea ration did not affect the level of orotic and UMP but increased the uridine concentration in blood plasma. During the parturition the lowest level of orotic acid in blood plasma, milk and urine was observed.

Animal Feed↗
PubMed1986

Plasma amino acid indices and urinary 3-methyl histidine excretion in dairy cows in early lactation.

The experiment was performed on six cows from parturition to the 70th day of lactation. The highest milk yield, from 23 to 36 kg FCM daily, was reached between the 25th and the 50th day of lactation. The onset of lactation was accompanied with the intensification of muscle protein catabolism expressed by the highest urinary 3-methyl histidine excretion and body mass loss. In the same time the lowest plasma level of insulin, glucose, alanine, threonine, serine, proline, citrulline, ornithine, arginine, and urea was stated. The PDI intake covered PDI requirement at the beginning of lactation, 5th-10th day, but exceeded it in the period between 25th and 70th day of lactation. It caused the decrease of urinary 3-methyl histidine excretion and the increase of plasma urea cycle metabolites (ornithine, citrulline, arginine, urea) level.

Amino Acids↗
PubMed1985

Protein supplement resistant against ruminal degradation as a factor improving utilization of urea in ruminant feeding.

The metabolic and productive effects of the blood meal and formaldehyde (FA) treated casein supplements (5-10% of crude protein content) given with urea concentrates in sheep and fattening bulls were investigated. The blood meal has a similar composition of essential amino acids (EAA) to casein. The mean solubility of the FA treated casein and the blood meal after 6 hours of incubation in the sterilized rumen contents amounted 10.5% and 8.5% respectively. The average rumen ammonia concentration and plasma urea level was the highest in bulls fed urea ration without protected protein supplement. The supplementation of this ration with blood meal diminished the large daily fluctuation of plasma AA level and increased plasma EAA/NEAA ratio. The blood meal supplement improved the nitrogen retention in sheep (14%) and body gains in bulls (9%) but did not influence digestible coefficients and rumen protein synthesis in sheep.

Animals↗
PubMed1984

Investigations of the influence of the content of plant crude protein in the ration on the utilisation of urea in dairy cattle. 5. 15N-fractions in the blood of lactating cows given 15N-urea intraruminantly.

The incorporation of urea-15N (given as an intraruminal drench or infusion) into plasma urea and protein of dairy cows fed isoenergetic rations with different levels of plant protein (9, 11, 12, 14, 15 and 17% in DM) was investigated. A nonlinear and asymptotic dependence between the plasma concentration of urea and protein level in the ration was stated. The availability of dietary urea-15N for plasma urea for 48 hours after administration was lowest in cows fed with low protein rations (9 and 11% of plant protein). On the contrary the highest incorporation of urea-15N into plasma protein of these animals was observed. The possible explanation of these results is presented.

Animals↗
PubMed1984

The influence of urea diet supplemented with protected protein on metabolism and wool growth in sheep.

The utility of blood meal and formaldehyde treated casein as protein supplements in the nutrition of sheep receiving approximately 50% of their total nitrogen from urea was studied. It was observed that protected protein supplements positively influenced wool growth and quality. On the basis of biochemical analysis of blood the mechanism of this effect is discussed. It seems that small protein supplements (about 6% of the total protein) are not only a source of amino acids in the duodenum but also influence the hormonal control in animals.

Amino Acids↗
PubMed1984

Species comparison of the influence of ammonia on orotic acid and urea biosynthesis in liver.

Although orotic aciduria occurs in both male and female rats fed an arginine-deficient diet, only hepatocytes from male rats exhibited an enhanced rate of orotate biosynthesis to increasing ammonium compared to controls. Inhibition of incorporation [14C]NaHCO3 into urea by norvaline in the rat and mouse was accompanied by a 20 and 25% increase in orotate biosynthesis, respectively. Injection of ammonium chloride (2 mmol/kg) or consumption of a diet devoid of arginine resulted in an increased urinary orotate excretion in the rat. Injection of a similar quantity of ammonium chloride in mice did not result in an orotic aciduria. The influence of ammonia and arginine on the biosynthesis of orotic acid and urea in isolated liver slices from various mammals was also examined. In rat, mouse and pig liver, increasing quantities of ammonia stimulated the incorporation of [14C]NaHCO3 into orotic acid. In porcine, bovine and ovine liver the incorporation of [14C]NaHCO3 into orotic acid was low and was minimally effected by supplemental ammonia. Addition of arginine to the incubation medium diminished the incorporation of [14C]NaHCO3 into orotic acid in the liver of all species examined except the cow and sheep. This decrease was accompanied by a stimulation of urea biosynthesis in the rat, but a depression in the pig. Addition of ammonium (5.0 mM) markedly increased the incorporation of [14C]NaHCO3 into urea in all mammalian liver slices examined. These studies show that the liver of various mammals can respond to increasing ammonia by increasing orotic acid biosynthesis. However, species differences in the response to ammonia are evident.

Ammonia↗
PubMed1981

Inhibitory action of intravenously administered ammonium acetate on the motility of the rumen in sheep.

The effect of 60 minutes' intravenous infusions, before morning feeding, of ammonium acetate (18.6 micromole/min/kg of body weight) and ammonium acetate with propranolol (11 microgram/min/kg of body weight) on the ruminal motility of sheep was examined. Ammonia has a adrenaline-like action therefore propranolol, a beta-receptor blocking agent, was administered in order to eliminate the possible effect of adrenaline on ruminal motility. The contractions of the dorsal sack of the rumen were registered by means of the balloon method, with the gauge inserted through the rumen fistula. The infusion of ammonium acetate caused an increase of the ammonia concentration in the blood to 0.6 mmol/1 at the end of 60 minutes' infusion. Already during the first 5 minutes of the intravenous infusion of ammonium acetate there was a decreased frequency of ruminal contractions, which was observed throughout the infusion. After the infusion there was a radical decrease of the concentration of ammonia in the blood, and at the same time an increase in the frequency of rumen contraction was observed. Blocking of the beta-adrenergic receptors by propranolol did not eliminate the inhibiting action of ammonium ion on rumen motility. The infusion of the ammonium acetate caused an increase of adrenaline and glucose concentration. This response was eliminated by propranolol in the case of adrenaline but not glucose. It is assumed that the action of ammonium ion on the rumen motility is derived primarily by the central nervous system.

Acetates↗