Biomedical subjects

M Hidiroglou

Publications and source records attributed to M Hidiroglou.

At least 19 recordsLinked to original sources

PubMed1999

Pharmacokinetic study of 45Ca administered intravenously following intramuscular injection of vitamin D3 or 25-hydroxyvitamin D3 in early weaned lambs.

The objective of this study was to evaluate the pharmacokinetic parameters of 45Ca administered intravenously at a dose of 50 microCi in young lambs. The experiment was performed on 18 female lambs allocated to three treatments. Six animals received intravenous calcium only; six received intramuscularly vitamin D3 8 days prior to the administration of calcium; and six received intramuscularly 25-hydroxyvitamin D3 5 days prior to the administration of calcium. Blood samples were collected from 15 min up to 8 days after the administration of 45Ca. The different pharmacokinetic parameters (area under the curve, clearance, mean residence time and volume of distribution) were estimated using non-compartmental and compartmental approaches. Statistical analysis of the results showed no significant differences in the pharmacokinetic parameters of the three groups. It can be concluded that vitamin D does not modify either the elimination or the distribution of calcium in the lambs receiving adequate dietary vitamin D.

Animals↗

PubMed1999

Technical note: forms and route of vitamin C supplementation for cows.

The purpose of this study was to compare the effect of multiple oral supplementation of two forms of vitamin C on plasma ascorbic acid concentrations in dairy cows. Vitamin C was administrated at the rate of 40 g/d during a 5-d period. The supplements were vitamin C in the form of a fine powder and vitamin C coated with ethyl cellulose. In addition, another group of cows provided with vitamin C in the form of fine powder through an abomasal fistula was enrolled in the study. The effect of vitamin C supplementation was assessed by the change in plasma ascorbic acid concentrations during a 5-d period of vitamin C supplementation. A tendency existed for cows that were dosed with vitamin C in the abomasum to have higher ascorbic acid than cows supplemented orally. In the abomasum-dosed cows, plasma ascorbic acid value varied between 3.6 and 4.4 micrograms/ml; the maximum ascorbic acid content was 4.4 micrograms/ml at 54 h. Cows dosed orally with vitamin C coated with ethyl cellulose had higher plasma ascorbic acid concentrations than did cows that received vitamin C in the form of fine powder. In the former group, the maximum ascorbic acid concentration occurred at 30 h after dosing (5 micrograms/ml).

Abomasum↗

PubMed1997

Ascorbic acid disposition kinetics in the plasma and tissues of calves.

Kinetic plasma disposition parameters and tissue distribution of ascorbic acid (AA) and dihydroascorbic acid (DHA) were determined in newborn calves. After a radiolabeled AA intravenous administration, the plasma clearance (Cl) was low (40.8 +/- 9.5 ml.kg-1.h-1), the steady-state volume of distribution (Vss) was very high (8.9 +/- 2.2 l/kg), and the AA mean residence time (MRT) was long (230 +/- 85 h). After administration of a 3-g dose of AA, the Cl was high (450 +/- 146 ml.kg-1.h-1), the Vss was low (0.658 +/- 0.236 l/kg), and the MRT was short (1.49 +/- 0.41 h), indicating a strong nonlinearity of AA disposition in calves and the impossibility of preventing scurvy with the use of a loading AA dose. Nonlinearity was explained by the saturation of both kidney reabsorption and tissue uptake. The estimated AA body pool size was 23.1 +/- 6.8 mg/kg. On the basis of a compartmental analysis and actual tissue concentration measurements, it is suggested that the lung (19% of the pool) constitutes a low-capacity but rapidly mobilized pool able to cover an acute need for AA, whereas muscle and liver (40 and 33% of the pool, respectively) are high-capacity AA pools, but slowly mobilized and involved in covering the calf's long-term AA requirements. The average daily AA entry rate over the first 7 days of life was 3.43 +/- 1.16 mg/kg, and it is suggested that the calf is able to synthesize AA at an early stage.

Animals↗

PubMed1997

Bioavailability of vitamin E compounds and the effect of supplementation on release of superoxide and hydrogen peroxide by bovine neutrophils.

The effects of daily supplementation of 1000 IU of d-alpha- or dl-alpha-tocopherol acetate to Holstein cows from drying off to 8 wk after calving were studied 1) to compare the bioavailability of d-alpha- and dl-alpha-tocopherol acetate by monitoring vitamin E concentrations in plasma, red blood cells, and neutrophils and 2) to determine the effect of d-alpha- and dl-alpha-tocopherol acetate supplementation on O2- and H2O2 release by neutrophils. Supplementation with d-alpha- or dl-alpha-tocopherol acetate increased vitamin E concentrations in blood plasma, red blood cells, and neutrophils; the d-alpha form was more effective than was the dl-alpha form. Supplementation with d-alpha- or dl-alpha-tocopherol acetate had no effect on the release of O2- and H2O2 by neutrophils, suggesting no harmful effects on surrounding tissues from oxygen-free radicals produced by neutrophils.

Animals↗

PubMed1996

Effect of oral supplements of vitamin A on the plasma retinol levels in calves and their immunological unresponsiveness.

Forty calves were used to evaluate the immune response effects induced by a wide range of dietary vitamin A intake levels. The immune response was not affected by the tested doses of vitamin A administered orally during a 56 day period. There was no change in plasma immunoglobulin concentrations and no difference in specific antibody titres following injection of keyhole limpet haemocyanin (KLH) at 10, 20 and 40 days of age. Some small and temporary variations were recorded in the plasma vitamin A concentration following daily oral administration of various doses up to 10,000 IU. Only oral supplementation of 20,000 IU of vitamin A daily over 50 days significantly increased the plasma level of vitamin A.

Aging↗

PubMed1996

Pharmacokinetic profile of plasma tocopherol following intramuscular administration of acetylated alpha-tocopherol to sheep.

Five sheep, with a mean BW of 45 kg, were given a single i.m. injection (600 IU) of dl-alpha-tocopherol acetate. Plasma concentration of alpha-tocopherol was best fitted to a single-compartment model. Two successive absorption processes were selected. The individual pharmacokinetic parameters were absorption rate constant, Ka1 = 0.29 +/- 0.02/h; the second absorption rate constant, Ka2 = 0.03 +/- 0.002/h; elimination half-life = 42.40 +/- 1.70/h; mean residence time = 46 +/- 0.92 h; and area under the curve = 290 +/- 10.77 micrograms/h per ml. During the first absorption process, elimination half-life was 2.46 +/- 0.22 h, and the second elimination half-life was 21.20 +/- 1.72 h. The peak concentration of vitamin E plasma (4.78 +/- 0.23 micrograms/ml) was observed at 14.6 +/- 4.08 h after i.m. injection. The increase in vitamin E concentration occurred because of gradual hepatic hydrolysis of the absorbed acetylated tocopherol.

Acetylation↗

PubMed1996

Pharmacokinetic study of ascorbic acid in sheep.

Four groups of sheep (5/group) were used in the experiment. Group 1 sheep were given 1 g of ascorbic acid (AA) intravenously (i.v.), group 2 were given 3 g i.v., group 3 were given 1 g intramuscularly (i.m.) and group 4 received 3 g i.m. Blood was collected for 7 h after i.v. administration and for 48 h following i.m. administration. Plasma was analyzed for AA using HPLC techniques. After i.v. administration the rate of elimination was greater at the high dose than the low (0.8560 vs 0.5231 h-1) but the area under the curve (AUC) parameter was proportional to the dosage (127.9 vs 39.7 mcg*h/mL). After i.m. administration AUC parameters were higher than following the i.v. injections. When the times that AA levels were > or = 5 mcg/mL after i.m. injection were compared there was no significant difference between the 1 and 3 g dosages. Times that levels were > or = 10 mcg/mL were significantly longer for the 3 g dose. Using the AUC (area under the curve) parameter as an index of drug exposure, supplementation of adult sheep with AA by the i.m. route should have a greater effect on the animal than i.v. administration.

Animals↗

PubMed1995

Effect of vitamin E supplementation on immune status and alpha-tocopherol in plasma of piglets.

Twelve (Yorkshire) gilts were assigned to 2 dietary fat supplement groups starting at 57 d of gestation. Group 1 received no fat and Group 2 was supplemented with 5% Canola oil. Each group was supplemented with 0.1 ppm Se and 22 IU of DL-alpha-tocopherol acetate/kg of feed. Colostrum (d 0) and milk (7, 14, 21 and 28 d post partum) were sampled from gilts. At farrowing 3 piglets from each gilt of both groups were injected with alpha-tocopherol at birth (500 IU) and at 7 and 14 d (1,000 IU) of age and 3 piglets were injected with saline and used as control. Blood samples were taken from the newborn piglets at birth and at 7, 14, 21, 28 and 35 d of age. alpha-Tocopherol concentration in the colostrum of gilts was significantly higher than in the milk. Plasma alpha-tocopherol concentrations and antibody titres to Key-hole limpet haemocyanin of piglets injected with vitamin E were significantly higher than the control piglets. Vitamin E injected piglets had significantly higher alpha-tocopherol concentrations in spleen, liver, kidney, heart, lung and hip muscle than the control piglets.

Animals↗

PubMed1995

Pharmacokinetics and tissue uptake of D-alpha-tocopherol in sheep following a single intraperitoneal injection.

D-alpha-Tocopherol in an emulsible base was administered i.p. to four groups of five sheep each at doses of 0, 1250, 2500, and 5000 IU. Blood was sampled regularly until slaughter at 7 d after administration. Plasma and tissue concentrations of D-alpha-tocopherol were measured by HPLC. Pharmacokinetic analysis of plasma concentrations, for the three tested doses, showed an absence of significant difference for lag time to absorption (.9 to 2.5 h), half-time of absorption (15 to 30 h), plasma half-life (31 to 42 h), and time of maximal concentration (18 to 31 h). In contrast, dose had a significant effect on area under the tocopherol plasma curve and on the maximal concentration. For both parameters, statistical evidence indicated nonlinearity for disposition of D-alpha-tocopherol, but without biological significance; by 7 d after dosing, amounts of residue of tocopherol were highest in the pancreas and adrenal glands (approximately 65 and 47 micrograms/g, respectively, for the 5000 IU dose) and lowest in neck muscle (approximately 4 micrograms/g for the 5000 IU dose). Kidney had an intermediate level of tocopherol. The intraperitoneal route is an efficient route for tocopherol administration in sheep.

Absorption↗

PubMed1995

Effects of supplemental vitamins E and C on the immune responses of calves.

Two experiments were conducted to evaluate the effects of oral supplementation of vitamin C and vitamin E (alpha-tocopherol), alone and in combination, on immune responses of calves. In Experiment 1, 18 Holstein newborn female calves were supplemented with 0, 1, and 2 g/d of vitamin C from birth to 6 wk of age. Concentrations of ascorbic acid in blood plasma were significantly higher for supplemented calves than for control calves. No significant differences among treatments occurred in the concentrations of IgG1, IgG2, and titer to keyhole limpet hemocyanin. In Experiment 2, effects of oral supplementation of vitamins E and C on immune responses were studied using 18 Holstein female calves. Concentrations of alpha-tocopherol in blood plasma were significantly higher for supplemented than for control calves. The concentrations increased from birth to wk 1, and then very little change occurred from wk 1 to 6. Differences among treatments in the concentrations of IgG1, IgG2, IgM, and titer to keyhole limpet hemocyanin were not significant; however, concentrations of IgM in calves supplemented with vitamins E and C generally tended to be higher than those of control calves. Antibodies to keyhole limpet hemocyanin were higher at 6 wk than at 4 wk of age.

Animals↗

PubMed1995

Effects of vitamin E injection on body temperature and plasma alpha-tocopherol concentrations in pigs, lambs and calves.

Fifteen pigs, 15 lambs, and 15 calves were used to study the effect of supplementation of vitamin E on body temperature and plasma alpha-tocopherol concentrations following 1 intramuscular injection in 3 doses (1x, 3x, 5x). The 1x doses for pig, lamb, and calf were 500, 1,000, and 1,500 IU, respectively. Data on body temperature and plasma alpha-tocopherol concentration were analyzed by least-squares procedures separately for each species. In each species plasma alpha-tocopherol concentration increased with increase in the dose of vitamin E injection, highest on d 1 postinjection and declined slowly throughout the remaining observation period. There was a transient elevation of body temperature on d 1 and 2 after injection in all species.

Animals↗

PubMed1995

Effects of vitamin E on immune function of dairy cows.

The effect of vitamin E supplementation on the immune function of dairy cows was studied. Twelve cows were assigned to 1 of the 2 experimental groups: control (no vitamin E supplementation), and vitamin E-supplemented. Supplementation of vitamin E started 4 weeks before and continued up to 8 weeks after parturition and included oral supplementation of vitamin E at the rate of 3,000 IU/cow/d. In addition, the same group of cows received 1 injection of vitamin E (5,000 IU), 1 week prior to the expected date of parturition. Data indicated that blood neutrophils isolated from control cows produced twofold less (P < 0.05) superoxide anion after parturition, compared with the corresponding value before parturition. Furthermore, blood macrophages isolated from control cows produced 15 and 35% (P < 0.05) less interleukin 1 (IL-1) and major histocompatibility (MHC) class-II antigens, respectively, after parturition, compared with the corresponding values before parturition. These data, collectively, indicate that functions of blood macrophages and neutrophils are depressed during the early postpartum period in control cows. In contrast, there were no differences in superoxide anion production by blood neutrophils, or in IL-1 production, and MHC class-II antigen expression by blood macrophages before and after parturition in cows supplemented with vitamin E. There were no differences in lymphocyte proliferation, or IL-1 production and MHC class-II antigen expression by mammary macrophages when control and vitamin E-supplemented cows were compared. We conclude that vitamin E prevented suppression of blood neutrophil and macrophage function during the early postpatum period.

Analysis of Variance↗

PubMed1994

Effect of supplementing gilts' diets with different levels of vitamin E and different fats on the humoral and cellular immunity of gilts and their progeny.

The effects of supplementing gestation and lactation diets of gilts with different combinations of vitamin E at or above NRC recommended levels (22, 44, or 88 IU/kg during gestation and 55, 110, and 220 IU/kg during lactation) and types of fat (5% added tallow or fish oil or no added fat) on humoral and cellular immunity of gilts and their pigs were evaluated. With only two exceptions, total IgG, IgM, and IgA in colostrum, milk, and plasma of gilts and in plasma of their pigs did not show significant (P > .05) effects, and no interactions between vitamin E and fat supplementation were observed. Cellular immunity was measured as lymphocyte proliferation response to phytohemagglutinin (PHA), concanavalin A (Con A), purified protein derivative of Mycobacterium avium, keyhole limpet hemocyanin, Escherichia coli lipopolysaccharide (LPS), and Salmonella typhimurium LPS. Only the nonspecific mitogens, PHA and Con A, induced proliferation of gilt and pig lymphocytes. Fish oil supplementation in the gilts' diets resulted in lower (P < .01) postpartum PHA response in gilts and slower (P < .05) acquisition of PHA response in newborn pigs compared with groups with added tallow or no added fat. The vitamin E supplementation did not have a significant positive effect on either PHA or Con A response of the gilts. However, the rate of acquisition of PHA response and Con A response in newborn pigs was greater (P < .05) for groups supplemented with 110 and 220 IU/kg of vitamin E than for the group supplemented with 55 IU/kg vitamin E.

Animals↗

PubMed1994

Metabolism of tritiated D-alpha-tocopherol and D-alpha-tocopheryl succinate in intraruminally dosed sheep.

The comparative disposition (absorption, plasma disposition, tissue distribution) of D-alpha-tocopherol and of D-alpha-tocopheryl succinate (forms of vitamin E) was investigated in 10 ruminally cannulated wethers. Tritiated tocopherols (4 microCi/kg BW) were administered directly into the rumen. Plasma and ruminal fluid activity were regularly measured from the time of administration to 96 h after administration. Radioactivity in lymph was measured in four additional wethers dosed intraruminally (100 microCi) with the same tritiated compounds. Lymph was collected from the cannulated thoracic duct during the first 24 h after the administration. Wethers were killed and selected tissues were measured for their tocopherol activity. Plasma and ruminal fluid specific activity vs time were modeled using appropriate compartmental and noncompartmental approaches. It was shown that there was a large difference in the relative bioavailability of the two compounds with a four times higher (P < .05) relative availability of D-alpha-tocopherol than of D-alpha-tocopheryl succinate. This was explained in terms of incomplete hydrolysis of tocopheryl succinate before absorption. By direct ruminal fluid measurement, it was estimated that tocopherol behaves similarly to a soluble ruminal marker with a ruminal transit time of approximately 19 h. In plasma, the total mean residence time was 148 h for D-alpha-tocopherol and 106 h for D-alpha-tocopheryl succinate. The lymph activity was mainly associated with tocopherol both after tocopherol and tocopheryl succinate administration. Tissue concentration of radioactivity was higher (P < .05) for sheep dosed with tocopherol than for those dosed with the tocopheryl succinate, confirming the difference in bioavailability of the two compounds.

Animals↗

PubMed1994

Changes in plasma alpha-tocopherol and selenium of gestating cows fed hay or silage.

The effects of dietary hay or silage on plasma alpha-tocopherol and Se concentrations during late gestation and early lactation were studied using 40 crossbred pregnant cows and their calves. Cows received solely either timothy hay or grass silage forage from midgestation to early lactation and 21 d prior to estimated calving were or were not injected with Se (30 mg) and alpha-tocopherol (3000 IU). Five blood samples were collected for determination of concentrations of alpha-tocopherol and Se twice during late gestation and three times after calving. Blood samples from calves were collected at birth and at 10 and 30 d of age. Serum concentrations of alpha-tocopherol were low at birth for both groups of calves and ranged from .83 to 1.08 micrograms/ml of plasma. Hay had less alpha-tocopherol than silage (15 vs. 35 ppm in the DM). Cows fed silage had significantly higher plasma alpha-tocopherol concentrations (3.41 micrograms/ml) than cows fed hay (2.25 micrograms/ml). Cows given one subcutaneous injection of Se plus alpha-tocopherol preparation had significantly higher Se concentration in plasma (30 ng/ml) than did cows in the control group (17 ng/ml). The Se concentration in the placenta of cows that were injected with the Se preparation was significantly higher (64 ppm) than that in the control (47 ppm). Plasma Se concentration of calves at birth was correlated significantly with that of dams soon after parturition.

Animal Feed↗

PubMed1993

Vitamin E and fat supplementation of sows and the effect on tissue vitamin E concentrations in their progeny.

A study was conducted to evaluate the effects of supplementing the diets of gestating and lactating sows with 3 levels of vitamin E (22, 44 or 88 IU/kg) and fat (no fat, 5% tallow, or 5% fish oil) on tissue vitamin E concentrations in their progeny. Tissue levels of vitamin E were examined at birth, and then at 14 and 28 d of age in the suckling piglets. Vitamin E concentration in all tissues at birth were very low (hip muscle, neck muscle, lung, brain, heart, kidney < 1.0 microgram/g tissue). Piglet tissue vitamin E levels at birth were influenced by the vitamin E status of the maternal diet during gestation. The piglet tissue concentration of vitamin E increased 2- to 3-fold by 14 d of age. Tocopherol concentrations greater than 3 micrograms/g tissue were found in the liver, lung, spleen, heart and kidney. Tissue vitamin E concentrations of piglets from sows that had received fish oil were lower (significantly in 5 cases: P < 0.05) than piglets from sows receiving tallow or no fat. Tocopherol concentrations in tissues, with the exception of the spleen, increased significantly (P < 0.05) with increased vitamin E in the sows' diet.

Animal Feed↗

PubMed1993

Effects of dietary vitamin E and fat on some serum enzymes in pigs.

Forty-five gilts (15 groups of 3 gilts) were used to study the supplementation of vitamin E and source of dietary fat on serum enzymes during gestation and early lactation, as well as in piglets born from these gilts from birth to 28 d of age. Gilts supplemented with 88 IU/kg diet of vitamin E or receiving fish oil had significantly lower alanine aminotransferase than those supplemented with 22 IU/kg diet of vitamin E. Differences in the enzyme activity between the treatment groups were small. Aspartate aminotransferase and creatine kinase were higher in gilts at farrowing than during either gestation or early lactation.

Alanine Transaminase↗

PubMed1993

Assessment of the oral administration of a high dose of retinol on vitamin E status of sheep.

The effect of dietary excess of retinol on vitamin E turnover in sheep's body was studied. Five of 10 adult Canadian Arcott sheep were given daily for 30 d an oral dose of 250 mg vitamin A as retinol palmitate, while the remaining sheep were used as control. Then a single oral dose of D-alpha(5-Me-3H) tocopherol (0.2 microCi/kg vitamin B) was administered to each sheep in both groups. The kinetic data were modelled as a 2-compartment model which provided a simple kinetic description of vitamin E absorption. The analysis showed no difference between the 2 groups of sheep regarding their various pharmacokinetic values. It is suggested that oversupply of dietary retinol does not antagonize vitamin E turnover in the sheep.

Administration, Oral↗