Hard water may increase the inhibitory effect of feed on the oral bioavailability of oxytetracycline in broiler chickens.

The aim of this study was to determine to what extent the ions present in hard water (125 mg/L of MgCl2 and 500 mg/L of CaCl2) may intensify the feed-induced decrease in oxytetracycline (OTC) absorption rate in broiler chickens after single oral administration at a dose of 15 mg/kg. Drug concentrations in plasma were determined by liquid chromatography-tandem mass spectrometry and combined, compartmental and non-compartmental approach was used to assess OTC pharmacokinetics. The administration of feed decreased the absolute bioavailability (F) of OTC from 12.70%±4.01 to 6.40%±1.08, and this effect was more pronounced after the combined administration of OTC with feed and hard water (5.31%±0.90). A decrease in the area under the concentration- time curve (AUC0-t), (from 10.18±3.24 µg·h/ml in control to 5.13 µg·h/ml±1.26 for feed and 4.26 µg·h/ml±1.10 for feed and hard water) and the maximum plasma concentration of OTC (Cmax) (from 1.22±0.18 µg/ml in control, to 1.01 µg/ml ±0.10 for hard water, 0.68 µg/ml±0.10 for feed and 0.61 µg/ml±0.10 for feed and hard water) was observed. The results of this study indicate that feed strongly decreases F, AUC0-t and Cmax of orally administered OTC. The ions present in hard water increase this inhibitory effect, which suggests that, therapy with OTC may require taking into account local water quality and dose modification, particularly when dealing with outbreaks caused by less sensitive microorganisms.

Differences in the pharmacokinetics of flumequine after single and continuous oral administration in non-fasted broiler chickens.

The aim of this study was to determine the influence of feed on the pharmacokinetics of flumequine (FLU) administered to broiler chickens as follows: directly into the crop (10 mg/kg of BW) of fasted (group I/control) and non-fasted chickens (group II), or administered continu- ously with drinking water (1 g/L for 72 h) and with unlimited access to feed (group III). Plasma concentration of FLU was determined by high-performance liquid chromatography with fluo- rescence detection. In group II, a significant decrease in the maximum concentration (Cmax = 2.13±0.7 µg/mL) and the area under the concentration curve from zero to infinity (AUC0→∞ = 7.47±2.41 µg·h/mL) was noted as compared to the control group (Cmax = 4.11±1.68 µg/mL and AUC0→∞ = 18.17±6.85 µg·h/mL, respectively). In group III, the decrease in AUC was signifi- cant only in the first 3 hours (AUC0→3 = 5.02±1.34 µg·h/mL) as compared to the control group (AUC0→3 = 7.79±3.29 µg·h/mL). The results indicate that feed reduced the bioavailability of FLU from the gastrointestinal tract by at least 50% after the administration of a single oral dose. However, continuous administration of FLU with drinking water could compensate for the feed-induced decrease in absorption after single oral dose.

Pharmacokinetics of tigecycline in turkeys following different routes of administration.

The aim of this research had been to determine the pharmacokinetics of tigecycline (TIG) in turkey after intravenous (i.v.), intramuscular (i.m.), subcutaneous (s.c.), and oral (p.o.) administration at a dose of 10 mg/kg. TIG concentrations in plasma were determined using high-performance liquid chromatography with tandem mass spectrometry. Mean concentrations of TIG in turkey plasma in the i.v. group were significantly higher than concentrations of this drug obtained after using the other administration routes. No significant differences were demonstrated in respect to the concentrations achieved after i.m. and s.c. administration. The bioavailability of TIG after i.m., s.c., and p.o. administration was 32.59 ± 5.99%, 34.91 ± 9.62%, and 0.97 ± 0.57%, respectively. Values of half-life in the elimination phase were 23.49 ± 6.51 hr, 25.42 ± 4.42 hr, and 26.62 ± 5.19 hr in i.v., i.m., and s.c. groups, respectively, values of mean residence time were 7.92 ± 1.41 hr, 19.62 ± 2.82 hr, and 17.55 ± 2.59 hr in i.v., i.m., and s.c. groups, respectively, whereas the volume of distribution was 14.85 ± 5.71 L/kg, 14.68 ± 2.56 L/kg, and 15.37 ± 3.00 L/kg in i.v., i.m., and s.c. groups, respectively. Because TIG is not absorbed from the gastrointestinal tract in turkeys to a clinically significant degree, this drug given p.o. could find application in commercial turkey farms only to treat gastrointestinal tract infections.

Effect of tigecycline on the production of selected cytokines and counts of murine CD4+ and CD8+ T cells - an in vitro study.

Due to the unrecognized effect of tigecycline (TIG) on CD4+ and CD8+ T cells, the present study has been undertaken in order to determine whether the drug can affect these cells in respect of their counts, and the production of IFN-γ, IL-17 (pro-inflammatory and immune-protective cytokines), IL-4 (anti-inflammatory and immune-protective cytokine), IL-10 and TGF-ß (anti-inflammatory and immune-suppressive cytokines). Murine lymphocytes were treated with TIG for 48 and 96 h at concentrations reflecting its plasma levels obtained in vivo at therapeutic doses, and at 10-fold lower concentrations. It was found that TIG neither affected substantially the percentage and absolute counts of entire CD4+ and CD8+ T cell populations nor influenced the Foxp3+CD25+CD4+ regulatory/suppressive T cell subset. Furthermore, the percentages of IL-4-, IL-10-, IL-17- and TGF-ß-producing CD4+ T cells were not altered following the exposure to TIG. Similarly, TIG did not influence IFN-γ production by CD8+ T cells. Thus, with respect to the parameters evaluated, TIG does not seem to exert immune-suppressive and anti-inflammatory effects.

Influence of leukotriene receptor antagonist on contractile activity of the porcine uterine smooth muscle in the luteal phase and in early pregnancy.

This study analysed the influence of montelukast (MON; 10-8 - 10-4 M), a cysteinyl leukotriene receptor 1 (CysLTR1) antagonist, on the contractility of the porcine uterine smooth muscle in the luteal phase of the oesterous cycle (n=8) and in early pregnancy (n=8). Stimulation of uterine strips in the luteal phase with MON has been shown to significantly reduce the amplitude of con- tractions, but not to affect the tension or frequency of contractions. A statistically significant tension increase and decrease in the frequency and amplitude of contractions was observed in pigs in early pregnancy. This suggests that MON has a different effect on the parameters under study in cyclic and pregnant pigs.

The influence of doxazosin on the contractility of the urinary bladder in female pigs with experimentally induced cystitis.

The present in vitro study investigated the influence of doxazosin on the contractility of the urinary bladder in female pigs with experimentally induced cystitis. Fifteen juvenile female piglets (18-20 kg body weight) were randomly assigned into three groups (n=5 animals each): i) control (clinically healthy animals, without doxazosin treatment), ii) animals with induced inflammation of the urinary bladder, but without doxazosin treatment (experimental group I) and iii) animals with inflamed bladder, treated orally with doxazosin (0.1 mg/kg body weight for 30 days; experimental group II). Thereafter, the pigs were sacrificed and strips of the bladder trigone were suspended in organ baths. The tension and amplitude of the smooth muscles was measured before and after exposition to 5-hydroxytryptamine (5-HT; 10-6-10-4 M), acetylocholine (ACh; 10-5-10-3 M) and norepinephrine (NE; 10-9-10-7 M). 5-HT caused an increase in the tension of contractions in all the groups and the amplitude in the experimental groups, however, the effect was higher in the experimental group I than in group II as compared to that found in the pre-treatment period. ACh caused an increase in the tension in the control group and a decrease in the amplitude in both experimental groups; these changes significantly differed between the control and doxazosin-treated group. NE caused a decrease in the tension in both experimental groups and amplitude in all the groups, however, the effect was most strongly expressed in doxazosine-treated group. The present study has revealed that long-term administration of doxazosin causes a desensitization of the detrusor smooth muscle to in vitro applied mediators in the autonomic nervous system.

Determination of tigecycline in turkey plasma by LC-MS/MS: validation and application in a pharmacokinetic study.

Tigecycline (TIG), a novel glycylcycline antibiotic, plays an important role in the management of complicated skin and intra-abdominal infections. The available data lack any description of a method for determination of TIG in avian plasma. In our study, a selective, accurate and reversed-phase high performance liquid chromatography-tandem mass spectrometry method was developed for the determination of TIG in turkey plasma. Sample preparation was based on protein precipitation and liquid-liquid extraction using 1,2-dichloroethane. Chromatographic separation of TIG and minocycline (internal standard, IS) was achieved on an Atlantis T3 column (150 mm × 3.0 mm, 3.0 µm) using gradient elution. The selected reaction monitoring transitions were performed at 293.60 m/z → 257.10 m/z for TIG and 458.00 m/z → 441.20 m/z for IS. The developed method was validated in terms of specificity, selectivity, linearity, lowest limit of quantification, limit of detection, precision, accuracy, matrix effect, carry-over effect, extraction recovery and stability. All parameters of the method submitted to validation met the acceptance criteria. The assay was linear over the concentration range of 0.01-100 µg/ml. This validated method was successfully applied to a TIG pharmacokinetic study in turkey after intravenous and oral administration at a dose of 10 mg/kg at various time-points.

Influence of ß2- and ß3-adrenoceptor agonists on contractile activity of the porcine myometrium in the luteal phase and the first days of pregnancy.

This study analysed the relaxant properties of salbutamol (ß2-adrenoceptors agonist) and BRL 37344 (ß3-adrenoceptors agonist) regarding the contractility of porcine myometrium on days 10-14 of the oestrous cycle (cyclic group; n = 10) and on days 3-5 of pregnancy (early pregnant group; n = 6). The activity of myometrial strips (tension, frequency and amplitude) was recorded under isometric conditions using force transducers. The contractility was assessed further following the administration of increasing concentrations of the agonists (10-9-10-4 M), both with and without ß-adrenoceptor antagonists (butaxamine - a selective ß2- adrenoceptor antagonist, propranolol- a non-selective ß1- and ß2-adrenoceptor antagonist and bupranolol - a non-selective ß1-, ß2- and ß3-adrenoceptor antagonist) at a concentration of 10-4 M. Although neither salbutamol nor BRL 37344 caused changes in the tension, at the highest concentrations they decreased the frequency and amplitude of contractions. These changes were more evident after salbutamol treatment and in the early pregnant group. Antagonists given alone did not cause changes in the parameters examined but changed some activity of the agonists. Butoxamine reduced the decrease in frequency and amplitude induced by salbutamol and produced a decrease in the tension after BRL 37344 treatment in the early pregnant group. Propranolol reduced the decrease in frequency and amplitude induced by salbutamol in both examined groups and did not cause significant changes in BRL 37344 activity. The administration of bupranolol before salbutamol treatment caused an increase in the tension and reduced the decrease in the frequency in the cyclic group. Moreover, bupranolol eliminated a decrease in frequency and induced an increase in amplitude caused by BRL 37344 in both groups and these changes were more evident in the early pregnant group. The data indicates that both ß2- and ß3-adenoreceptors are involved in the regulation of the contractility in both groups, but the changes after agonists and antagonists treatment are more evident in the early pregnant myometrium.

ß- and ß-adrenergic receptors stimulation relaxes porcine myometrium in the peri-implantation period.

These studies were to demonstrate whether the ß-receptor is involved in regulating the contractility of the swine myometrium in the peri-implantation period and to compare a relaxing activity of selective ß- and ß-adrenergic agonists (salbutamol and BRL 37344, respectively). Myometrial strips were collected form the gilts ( = 8) on d 12 to 14 of pregnancy. Changes in the contractility of myometrial strips were assessed further to the administration of increasing concentrations of the agonists (10 to 10 ) with and without ß-adrenergic receptor antagonists: butoxamine, propranolol, and bupranolol at 10 . Moreover, the -log EC (pD) of the agonists were compared. Following the incubation of myometrial strips with salbutamol and BRL 37344, a significant ( < 0.05 to 0.001) reduction in the contractility, seen as decreased tension, amplitude, and frequency of contractions, as compared to the pretreatment period was noted, although salbutamol induced these changes at a concentration of 10 to 10 , whereas BRL 37344 induced them at 10 to 10 . Salbutamol exerted a significantly ( < 0.001) more potent reduction of the tension (pD = 6.98 ± 0.93 [SD]) than BRL 37344 (pD = 3.41 ± 0.1.61). The impact of salbutamol was neutralized by all administered antagonists, while a relaxing effect of BRL 37344 was completely inhibited by bupranolol and partially by propranolol. The data indicate that the ß-adenergic receptor is involved in the regulation of smooth muscle contractility in the swine uterus in the peri-implantation period and its activation triggers relaxation of the myometrium to a lesser degree than the activation of the ß-adrenergic receptor.

Metal ion-oxytetracycline pharmacokinetic interactions after oral co-administration in broiler chickens.

The influence of the composition of calcium (Ca(2+)), magnesium (Mg(2+)), and iron (Fe(3+)) ions in two concentration levels (low-500 mg/L of CaCl2, 125 mg/L of MgCl2, and 10 mg/L of FeCl3 and high-2,500 mg/L of CaCl2, 625 mg/L of MgCl2, and 50 mg/L of FeCl3) contained in water on the pharmacokinetics (PK) of oxytetracycline (OTC) was determined. OTC hydrochloride was administered at a dose of 25 mg/kg of body weight to broiler chickens divided into four groups of nine birds each, including 3 oral groups (in deionized water -control, in water with low ion concentration, and in water with high ion concentration) and 1 intravenous group. OTC concentrations in plasma were determined using liquid chromatography-tandem mass spectrometry, after which non-compartmental pharmacokinetic analysis was conducted.The absolute bioavailability of OTC in the group of birds exposed to higher ions concentration was reduced (8.68% ± 2.56) as compared to the control (13.71% ± 2.60). Additionally, in this group, decrease in PK parameters such as: area under the concentration-time curve from 0 to infinity (15.36 µg × h/mL ± 4.36), from 0 to t (14.78 µg × h/mL ± 4.37), area under the first moment of curve from 0 to t (107.54 µg × h/mL ± 36.48), and maximum plasma concentration (2.13 µg/mL ± 0.32) were also observed. It is noteworthy, all mentioned parameters demonstrated a downward trend with high correlation coefficient (P = 0.004, P = 0.002, P = 0.005, P = 0.004, P = 0.011, respectively), reflecting the influence of increasing concentrations of Ca(2+), Mg(2+), and Fe(3+) ions on the decreasing absorption rate of OTC.Based on the current research results, it can be assumed that high concentrations of several ions applied concomitantly are able to decrease the absorption of OTC from gastrointestinal tract in broiler chickens. This occurrence might impair the drug's clinical efficacy toward some pathogenic microorganisms. It implies that using OTC on a farm may require administration of higher doses than the routine one when infections are caused by less sensitive pathogens.

Distribution of CD4+CD8+ double positive T cells in a mouse model of allergic asthma.

The present study describes the distribution of CD4+CD8+ double-positive (DP) T cells in various immune compartments of mice with ovalbumin (OVA)-induced allergic asthma. It was found that the absolute number of DP T cells was considerably increased in the mediastinal lymph nodes and lungs of asthmatic mice as compared with that determined in the healthy subjects. On the contrary, the absolute counts of DP T cells was significantly decreased in the head and neck lymph nodes, and in peripheral blood of OVA-immunized mice. These results suggest that DP T cells may be involved in the pathogenesis of allergic asthma.

A comparison of the efficacy and pharmacokinetics of ivermectin after spring and autumn treatments against Cyathostominae in horses.

The aim of the present study was to determine the efficacy of ivermectin against Cyathostominae infections and to describe the drug's pharmacokinetic parameters during two seasonal deworming treatments in horses. The study was performed on warm-blooded mares aged 3-12 years weighing 450-550 kg. A single bolus of an oral paste formulation of ivermectin was administered at a dose of 0.2 mg/kg BW in spring and autumn. Fecal samples were tested before treatment and 1, 2, 3, 4, 6, 10, 20, 30, 40, 50, 60, 75 days after treatment. Ivermectin concentrations in blood samples collected before treatment, 0.5, 1, 2, 3, 4, 6, 12, 24, 36 and 48 hours after treatment, and 3, 4, 6, 8, 10, 15, 20, 25, 30, 40, 50, 60 and 75 days after drug administration were determined by high pressure liquid chromatography. Drug absorption was significantly (p<0.05) slower (tmax: 21.89±11.43 h) in autumn than in spring (tmax: 9.78±8.97 h). Maximum concentrations (Cmax) of ivermectin in the blood plasma of individual horses (8.40-43.08 ng/ml) were observed 2-24 h after drug administration during the spring treatment and 2-36 h (6.43-24.86 ng/ml) after administration during the autumn treatment. Significantly higher (p<0.05) ivermectin concentrations were found during the first 4 hours after administration in spring in comparison with those determined after the autumn treatment. The administration of the recommended dose of ivermectin resulted in 100% elimination of parasitic eggs from feces in spring and autumn treatment.

The influence of leukotrienes C4 and D4 on the contractility of an inflamed porcine uterus.

The effect of leukotriene (LT) C4 (LTC4) and LTD4 on the contractility of an inflamed porcine uterus was investigated. On Day 3 of the estrous cycle (Day 0 of the study), either saline or Escherichia coli suspension was injected into each uterine horn. Although acute endometritis developed in all bacteria-inoculated gilts, a severe acute endometritis was noted more often on Day 8 than on Day 16. Myometrial and endometrial/myometrial strips were incubated with LTC4 or LTD4 alone, or together with a cysteinyl-LT receptor antagonist (BAY-u9773). Leukotriene C4 increased the contraction intensity in the saline- and bacteria-treated uteri on Day 8; however, its effect was lower in the myometrium of inflamed uteri. Contraction frequency was found to decrease in the saline-treated uteri as opposed to inflamed ones, in which it was elevated. On Day 16, contraction intensity increased in response to LTC4 in the saline-treated uteri but was reduced in the inflamed organs. The value of this parameter was lower in the inflamed uteri than that in the saline-treated ones. Leukotriene D4 (Days 8 and 16) augmented contractility in the saline-treated uteri, but despite increasing its intensity in the inflamed organs, it decreased contraction frequency. Leukotriene C4 or LTD4, added to BAY-u9773-pretreated saline- and bacteria-treated uteri on both days, decreased the contraction intensity. On Day 16 after treatment with BAY-u9773 and LTC4, contraction intensity in the endometrium/myometrium of the inflamed uteri was lower than that in the saline-treated organs. Data show that both LTC4 and LTD4 affect the contractility of inflamed porcine uteri, though LTC4 exerts a weaker contractile effect.

Comparison of flunixin meglumine and meloxicam influence on postoperative and oxidative stress in ovariohysterectomized bitches.

The aim of this study was to compare the effect of flunixin meglumine (FM) and meloxicam (M) on postoperative and oxidative stress in ovariohysterectomized bitches. Twenty four bitches were divided into three groups (n = 8 in each) and treated during premedication as follows: FM (2.2 mg/kg, iv, Fluvil, Vilsan, Turkey), M (0.2 mg/kg, sc, Maxicam, Sanovel, Turkey) or 0.9% saline (1 ml, iv, IE, Turkey)--control (C) group. The concentrations of serum cortisol, nitric oxide (NO), malondialdehyde (MDA), antioxidant potential (AOP) and glutation (GSH) were measured in blood samples collected during incision (0 h), closure of incision line (0.5 h) and 1, 2.5, 12 and 24 hours after incision. It was observed that cortisol level was higher at 0.5, 1 and 2.5 h in group C (p < 0.05), 0.5 h in group FM (p < 0.001), and 1 and 2.5 h in group M (p < 0.01), as compared to that determine at 0 h. Group C showed higher cortisol level during 0.5 h (p < 0.05) than that found in the other groups. Group FM displayed lower levels during 1 h (p < 0.01) and 2.5 h (p < 0.05) as compared to those observed in other groups. Concentrations of MDA, AOP and GSH between all the groups did not show any significant differences. MDA level was higher at 0.5 and 1 h in group M (p < 0.05) than that found in group C and it was the lowest at 2.5 h in group C (p < 0.05). AOP was higher at 2.5 h in group FM and M (p < 0.05) than that observed in group C, and at 12 and 24 h in group M than that found in group C and FM. GSH did not show any significant differences between the groups. NO level in group FM after 12 h was higher (p < 0.05) than that at 0.5, 1 and 24 h. Moreover, NO level was lower at 0.5 (p < 0.01), 1 (p < 0.05) and 24 h (p < 0.05) in group FM than that observed in group C and M. In conclusion, flunixin meglumine decreases cortisol and NO levels more efficiently than meloxicam. Therefore, it is suggested that postoperative stress following ovariohysterectomy may be prevented by flunixin meglumine in bitches.

Prostaglandin E2 inhibits IL-10 production by bovine CD4+ T cells.

Although prostaglandin E2 (PGE2) is a pro-inflammatory mediator, it also produces some effect which is anti-inflammatory in character. It is suggested that one of the mechanisms responsible for the latter effect is the increased synthesis of IL-10. The aim of this study has been to determine the influence of PGE2 on IL-10 production by bovine CD4+ and CD8+ T cells and NK cells. With this aim, peripheral blood mononuclear cells collected from 12-month-old heifers (n = 10) were treated without or with PGE2 (10(-6) M). Flow cytometric analysis showed that PGE2 caused a reduction in the percentage of IL-10 producing CD4+ T cells (P < 0.001), while leaving the secretion of this cytokine by CD8+ T cells and NK cells unaffected. This seems to indicate that PGE2 in cattle does not produce an anti-inflammatory effect by increasing the synthesis of IL-10; contrary to this, it may aggravate an inflammatory response by inhibiting the secretion of this cytokine by CD4+ T cells.

The influence of doxazosin, an alpha1-adrenergic receptor antagonist on the urinary bladder contractility in pigs.

In the present study influence of doxazosin on the porcine urinary bladder contractility has been examined. Immature pigs were treated for 30 days with: a) doxazosin (n = 5) per os at a dose of 0.1 mg/kg b.w. or b) placebo (n = 5; control group). Thereafter, animals were sacrificed and urinary bladder strips from the trigone were suspended in organ baths. The tension of the smooth musce was measured before and after exposition to acetylocholine (ACh; 10(-5) - 10(-3) M), norepinephrine (NE; 10(-9) - 10(-7) M) and 5-hydroxytryptamine (5-HT; 10(-7) - 10(-5) M). Both the ACh and 5-HT at the highest doses significantly increased the contractility in each group, but this response was weaker in doxazosin-treated animals. NE caused relaxation in both groups, but the effect was weaker in doxazosine-treated group. The results of our study have shown that long-term administration of doxazosin caused a desensitization of the detrusor smooth muscle for in vitro applied mediators of the autonomic nervous systems.

Pharmacological characteristics of metamizole.

Metamizole (dipyrone) is a popular analgetic, non-opioid drug, commonly used in human and veterinary medicine. In some cases, this agent is still incorrectly classified as a non-steroidal anti-inflammatory drug (NSAID). Metamizole is a pro-drug, which spontaneously breaks down after oral administration to structurally related pyrazolone compounds. Apart from its analgesic effect, the medication is an antipyretic and spasmolytic agent. The mechanism responsible for the analgesic effect is a complex one, and most probably rests on the inhibition of a central cyclooxygenase-3 and activation of the opioidergic system and cannabinoid system. Metamizole can block both PG-dependent and PG-independent pathways of fever induced by LPS, which suggests that this drug has a profile of antipyretic action distinctly different from that of NSAIDs. The mechanism responsible for the spasmolytic effect of metamizole is associated with the inhibited release of intracellular Ca2+ as a result of the reduced synthesis of inositol phosphate. Metamizole is predominantly applied in the therapy of pain of different etiology, of spastic conditions, especially affecting the digestive tract, and of fever refractory to other treatments. Co-administration of morphine and metamizole produces superadditive, antinociceptive effects. Metamizole is a relatively safe pharmaceutical preparation although it is not completely free from undesirable effects. Among these side-effects, the most serious one that raises most controversy is the myelotoxic effect. It seems that in the past the risk of metamizole-induced agranulocytosis was exaggerated. Despite the evidence showing no risk of teratogenic and embryotoxic effects, the drug must not be administered to pregnant women, although it is allowed to be given to pregnant and lactating animals. This paper seeks to describe the characteristics of metamizole in the light of current knowledge.

Sampling intervals verification in pharmacokinetics studies.

Regulatory agencies do not specify how to plan the sampling intervals in pharmacokinetics (PK) studies. Every interval between each sampling point forms one of the fractions of the area under the curve (AUC). The aim of this study is to propose a method of qualitative evaluation of PK studies, on the basis of the analysis of the partial AUC fields' values. For the pharmacokinetic analysis, average concentrations of high variability drug-itraconazole were used before (BO) and after sampling intervals optimization (AO). PK calculations were performed using Phoenix(TM) WinNonlin 6.3(®) (Certara L.P.) and in house software Biokinetica 4.0. Arithmetic formula and acceptance limit (AL%) was established, below which the mean of partial fields (MAF) value in PK study can be considered optimal. In case of MAF the CV% value before optimization was 125.35 and after the optimization 46.51. In the cases of AUC fractions for several partial fields BO data, the AL% value was exceeded. The values of AUC fractions did not exceed AL% established for AO data. The paper proposes an empirical method of quality assessment, made on the basis of the percentage of the AUC fractions. This method can be used in the quality assessment of PK studies.

Influence of prostaglandin F2α analogues on the secretory function of bovine luteal cells and ovarian arterial contractility in vitro.

Although prostaglandin (PG) F2α analogues are routinely used for oestrus synchronisation in cattle, their effects on the function of the bovine corpus luteum (CL), and on ovarian arterial contractility, may not reflect the physiological effects of endogenous PGF2α. In the first of two related experiments, the effects of different analogues of PGF2α (aPGF2α) on the secretory function and apoptosis of cultured bovine cells of the CL were assessed. Enzymatically-isolated bovine luteal cells (from between days 8 and 12 of the oestrous cycle), were stimulated for 24h with naturally-occurring PGF2α or aPGF2α (dinoprost, cloprostenol or luprostiol). Secretion of progesterone (P4) was determined and cellular [Ca(2+)]i mobilisation, as well as cell viability and apoptosis were measured. Naturally-occurring PGF2α and dinoprost stimulated P4 secretion (P<0.05), whereas cloprostenol and luprostiol did not influence P4 synthesis. The greatest cytotoxic and pro-apoptotic effects were observed in the luprostiol-treated cells, at 37.3% and 202%, respectively (P<0.001). The greatest effect on [Ca(2+)]i mobilisation in luteal cells was observed post-luprostiol treatment (200%; P<0.001). In a second experiment, the influence of naturally-occurring PGF2α and aPGF2α on ovarian arterial contraction in vitro, were examined. No differences in the effects of dinoprost or naturally-occurring PGF2α were found across the studied parameters. The effects of cloprostenol and luprostiol on luteal cell death, in addition to their effects on ovarian arterial contractility, were much greater than those produced by treatment with naturally-occurring PGF2α.

Dexamethasone, but not meloxicam, suppresses proliferation of bovine CD25+ CD4+ and CD25- CD4+ T cells.

Recently, we found that dexamethasone caused a depletion of CD25- CD4+ T cells, but it increased the number of CD25highCD4+ and CD25lowCD4+ T cells. We also determined meloxicam-induced increase in the number of CD25highCD4+ T cells. In view of this, and taking into consideration the latest reports indicating that meloxicam shows an anti-proliferative effect on bovine peripheral blood mononuclear cells, it was considered purposeful to determine the effect of both drugs on proliferation of bovine CD25highCD4+, CD25lowCD4+ and CD25- CD4+ T cells. Flow cytometry analysis and 5-bromo-2'-deoxyuridine incorporation assay were applied to detect the cell proliferation. It was demonstrated that dexamethasone, but not meloxicam, significantly reduced cell proliferation within all three evaluated CD4+ T cell subpopulations. Thus, the depletion of CD25- CD4+ T cells by treatment with dexamethasone can partly be the effect of the anti-proliferative action of the drug, however, dexamethasone-induced increase in the number of CD25highCD4+ and CD25IowCD4+ T cells cannot be the result of enhanced proliferation of these cells.