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Background: Renal replacement therapy (RRT), widely used in the treatment of renal injury during sepsis, aims to eliminate the toxins and proinflammatory cytokines involved in the pathomechanism underlying septic shock. Dialysis filters are characterized by a high adsorption potential for cytokines in RRT in the case of septic renal injury. For the treatment of sepsis with antibiotics, it is of key importance to achieve the desired values of PK/PD indices. Continuous renal replacement therapy (CRRT) may affect antimicrobial clearance, increasing their elimination in some cases. Methods: The aim of this study was to determine the degree of adsorption for linezolid on three different types of filters used in CRRT. In our in vitro study, a continuous veno-venous hemofiltration (CVVH) was conducted using three types of filters: polysulfone (PS), polyethyleneimine-treated polyacrylonitrile (PAN PEI), and non-PEI-treated polyacrylonitrile (PAN). Each type of filter was used in three CVVH cycles, involving the use of 600 mg of linezolid dissolved in 700 mL of bovine blood or in 700 mL of 0.9% NaCl. In each case, the total volume of the obtained solution was 1000 mL. Blood samples were collected at particular time points to measure their drug concentration. The differences in mean drug/NaCl adsorption and drug/blood adsorption were determined using a one-way ANOVA with multiple comparisons via Tukey's post hoc test; a p -value of <0.05 was considered significant. Results : A significant adsorption of linezolid was found for PAN PEI filters, both in samples obtained from bovine blood and 0.9% NaCl solutions, at the endpoint. In PAN PEI samples, the concentration of linezolid in 0.9% NaCl solutions decreased from 594.74 μg/mL to 310.66 μg/mL after 120 min (the difference was established at 52%). In blood samples, the initial concentration was 495.18 μg/mL, which then decreased to 359.84 μg/mL (73% of the beginning value). No significant adsorption was demonstrated on PAN or PS filters. Conclusion: There is a need for in vivo research to confirm the effect of filter type on linezolid concentration in patients undergoing CRRT.

To investigate the effects of (2,6-di-O-methyl)-β-cyclodextrin (DM-β-CD), (2-hydroxypropyl)-β-cyclodextrin (HP-β-CD), tocopherol polyethylene glycol 1000 succinate (TPGS), sodium desoxycholate (SDOCH), trimethyl chitosan (TMC), and sodium caprate (C10) on the plasma concentration and the oral bioavailability of tigecycline in broiler chickens. To test the effects of the excipients on absorption of tigecycline, a tetracycline that is poorly absorbed from the gastrointestinal tract, broiler chickens were used as an animal model. Tigecycline (10 mg/kg body weight) was administered intravenously, orally, and orally with one of the excipients. Plasma samples were taken after administration. To measure tigecycline concentrations, high-performance liquid chromatography coupled with tandem mass spectrometry was used. Compartmental and non-compartmental analyses were used for pharmacokinetic analyses of mean plasma concentrations versus time. With the exception of sodium caprate, all the excipients significantly increased the area under the curve and bioavailability of tigecycline ( p < 0.05). These parameters were approximately doubled by HP-β-CD, TPGS, and SDOCH, with 95% confidence intervals (95% CIs) for the difference that included only increases of 1.5-fold or higher (bioavailability: control, 1.67%; HP-β-CD, 3.24%; TPGS, 3.30%; and SDOCH, 3.24%). The increases in these parameters were smaller with DM-β-CD and TMC (DM-β-CD, 2.41%; TMC, 2.55%), and the 95% CIs ranged from close to no difference to nearly double the values in the control group. These results indicate that HP-β-CD, TPGS, and SDOCH substantially increase the area under the curve and oral bioavailability of tigecycline. They suggest that DM-β-CD and TMC may also substantially increase these parameters, but more research is needed for more precise estimates of their effects.

Objectives: To investigate how cyclosporine A, a nonspecific efflux-pump blocker, affects the plasma concentrations and oral bioavailability of tigecycline, oxytetracycline, chlortetracycline, doxycycline, minocycline, and tetracycline., Methods: Broiler chickens were used as an animal model. The tetracyclines (10 mg/kg BW) were administered intravenously, orally, and orally with cyclosporine A (50 mg/kg BW; administration: oral or intravenous). After administration, plasma samples were taken, and their concentrations of tetracyclines were measured using high-performance liquid chromatography coupled with tandem mass spectrometry. For pharmacokinetic analyses of mean plasma concentrations versus time, compartmental and non-compartmental analyses were used., Results: After oral administration of the tetracyclines, cyclosporine A administration (oral or intravenous) significantly (P < 0.05) increased the plasma concentrations, the bioavailability, the maximum plasma concentration, and the area under the curve of all the tetracyclines. Interestingly, the bioavailability of the tetracyclines was around two times higher after orally administering cyclosporine A than after intravenously administering it (P < 0.05)., Conclusions: Cyclosporine A administration increases the plasma concentrations of orally administered tetracyclines. Although cyclosporine A also inhibits renal and hepatic clearance, these results strongly suggest that efflux pumps in the intestinal epithelium are involved in the regulation of tetracycline absorption from the gastrointestinal tract., Competing Interests: Declaration of competing interest The author has declared no conflicts of interest., (Copyright © 2023 The Japanese Society for the Study of Xenobiotics. Published by Elsevier Ltd. All rights reserved.)

This study investigated the critical role of Glut1-mediated glucose metabolism in the inflammatory response of macrophages, which are energy-intensive cells within the innate immune system. Inflammation leads to increased Glut1 expression, ensuring sufficient glucose uptake to support macrophage functions. We demonstrated that using siRNA to knock down Glut1 reduces the expression of various pro-inflammatory cytokines and markers, such as IL-6, iNOS, MHC II/CD40, reactive oxygen species, and the hydrogen sulfide (H 2 S)-producing enzyme cystathionine γ-lyase (CSE). Glut1 activates a pro-inflammatory profile through a nuclear factor (NF)-κB, while silencing Glut1 can prevent lipopolysaccharide (LPS)-induced IκB degradation, blocking NF-κB activation. Glut1's role in autophagy, an essential process for macrophage functions such as antigen presentation, phagocytosis, and cytokine secretion, was also measured. The findings show that LPS stimulation decreases autophagosome formation, but Glut1 knockdown reverses this effect, increasing autophagy beyond control levels. The study highlights Glut1's importance in macrophage immune responses and its regulation of apoptosis during LPS stimulation. Knocking down Glut1 negatively impacts cell viability and mitochondrial intrinsic pathway signaling. These findings collectively suggest that targeting macrophage glucose metabolism through Glut1 could potentially serve as a target for controlling inflammation.

Ketamine and its enantiomer esketamine have gained much attention in recent years as potent, fast-acting agents for the management of treatment-resistant depression. However, an alternative to oral ketamine administration is required to ensure adequate systemic exposure as the drug undergoes extensive first-pass metabolism. We propose dry powder inhalation as a new esketamine delivery route. Here, we examine the pharmacokinetics, pharmacodynamics, toxicology and safety of this novel esketamine administration method. Esketamine (10 mg/kg) and ketamine racemate (20 mg/kg) were administered to rats by dry powder inhalation, intravenous injection or intratracheal instillation and the pharmacokinetics of these treatments were compared. Analyte concentration of ketamine stereoisomers and their metabolites was assessed by LC-MS/MS method. Esketamine showed a clinically relevant pharmacokinetic profile, with high bioavailability (62%) and relatively low maximum concentration peaks. Esketamine exhibited high penetration of the blood-brain barrier, but pharmacodynamic examinations of brain homogenates showed no changes in selected protein phosphorylation or expression analyzed by the immunoblotting method. We conducted GLP-compliant 14-day and 28-day general toxicity studies in rats and dogs, respectively, subjected to dry esketamine powder inhalation. The maximum daily dosages were 46.5 mg/kg and 36.5 mg/kg, respectively. We also performed pharmacological safety studies. Esketamine inhaled as dry powder had an expected safety profile consistent with its known pharmacological action. None of its observed effects were considered toxicologically significant. The pharmacological safety studies confirmed that the observed effects were transient and that inhaled esketamine had a good safety profile. Hence, our preclinical studies demonstrated that dry powder inhalation is a highly efficacious and safe delivery route for esketamine and may be a viable alternative administration route meriting further clinical development., (Copyright © 2022 Elsevier Ltd. All rights reserved.)

Agomelatine is a novel melatonergic antidepressant, with a non-monoaminergic mechanism of action. The aim of this study was to evaluate its plasma concentrations after a single oral dose of 300 mg/dog in fasted and fed status. The research was carried out in 6 adult healthy Labrador dogs according to a randomized open, single-dose, two-treatment, two-phase, paired 2 × 2 cross-over study. At the end of the study all the animals had received the drug in fasted and fed conditions. The drug concentrations were detected in plasma by a validated LC-MS/MS analytical method. The plasma concentrations of agomelatine were found to be extremely variable in both groups as well as the pharmacokinetic profiles. Due to these variable findings the only reliable pharmacokinetic parameters were assessed as C max (31.8 vs 15.7 ng/mL), T max (0.75 vs 4 h) and AUC (155 vs 52 ng h/mL) in fasted and fed status, respectively. Unfortunately, as a pioneer study, the small animal sample size used along with the unanticipated variability did not allow to neither statistically estimate if food can affect the pharmacokinetics of agomelatine nor recommend agomelatine for off-label therapies in canine species. Further studies are warranted to clarify this issue., (Copyright © 2021 Elsevier Ltd. All rights reserved.)

Each drug has pharmacokinetics that must be defined for the substance to be used in humans and animals. Currently, one of the basic analytical tools for pharmacokinetics studies is high-performance liquid chromatography coupled with mass spectrometry. For this analytical method to be fully reliable, it must be properly validated. Therefore, the aims of this study were to develop and validate a novel analytical method for 4-acetamidobenzoic acid, a component of the antiviral and immunostimulatory drug Inosine Pranobex, and to apply the method in the first pharmacokinetics study of 4-acetamidobenzoic acid in pigs after oral administration. Inosine Pranobex was administered under farm conditions to pigs via drinking water 2 h after morning feeding at doses of 20, 40, and 80 mg/kg. For sample preparation, we used liquid-liquid extraction with only one step-protein precipitation with 1 mL of acetonitrile. As an internal standard, we used deuterium labeled 4-acetamidobenzoic acid. The results indicate that the described method is replicable, linear (r 2 ≥ 0.99), precise (2.11% to 13.81%), accurate (89% to 98.57%), selective, and sensitive (limit of quantitation = 10 ng/mL). As sample preparation requires only one step, the method is simple, effective, cheap, and rapid. The results of the pilot pharmacokinetics study indicate that the compound is quickly eliminated (elimination half-life from 0.85 to 1.42 h) and rapidly absorbed (absorption half-life from 0.36 to 2.57 h), and that its absorption increases exponentially as the dose is increased.

The aim of this study was to assess the in vitro adsorption of antibiotics: vancomycin, gentamicin, ciprofloxacin and tigecycline on both polyethyleneimine-treated polyacrylonitrile membrane of AN69ST filter and polysulfone membrane of AV1000 filter using porcine blood as a model close to in vivo conditions. The porcine blood with antibiotic dissolved in it was pumped into hemofiltration circuit (with AN69ST or AV1000 filter), ultrafiltration fluid was continuously returned to the reservoir containing blood with antibiotic. Blood samples to determine antibiotic concentrations were taken at minutes 0, 5, 15, 30, 45, 60, 90 and 120 from the pre- blood pump of the hemofiltration circuit. To assess possible spontaneous degradation of the drug in the solution there was an additional reservoir prepared for each antibiotic, containing blood with the drug, which was not connected to the circuit. In the case of vancomycin, ciprofloxacine and tigecycline, a statistically significant decrease in the drug concentration in the hemofiltration circuit in comparison to initial value as well as to the concentrations in the control blood was observed, both for polyacrylonitrile and plolysulfone membrane. In the case of gentamicin, significant adsorption was noted only on polyacrylonitrile membrane. Our studies demonstrated that in full blood adsorption of antibiotics may be big enough to be of clinical significance. In particular in the case of polyacrylonitrile membrane.

The aim of this study was to compare the pharmacokinetics of ivermectin and its antiparasitic activity in two horse breeds. Eight Hutsul and 14 Toric horses were administered ivermectin orally at a dose of 0.2 mg/kg body weight. Blood samples were collected for 96 hr, and faecal samples were collected one day before and on days 14 and 21 after drug administration. Ivermectin concentrations in plasma samples were determined by high-performance liquid chromatography. Ivermectin concentration was significantly higher in Toric than in Hutsul horses 90 min after ivermectin administration and was maintained at higher level for up to 96 hr. The area under the concentration versus the time curve from 0 to the last sampling point (AUC 0→t ) and the maximum plasma concentration (C max ) were significantly higher in Toric than in Hutsul horses (1792.09 ± 246.22 μg × hr/L vs. 716.99 ± 255.81 μg × hr/L and 62.72 ± 17.97 ng/ml vs. 35.34 ± 13.61 ng/ml, respectively). No parasitic eggs were found in the faecal samples collected from both groups of horses on days 14 and 21 after drug administration. The obtained results indicate that although the pharmacokinetics of ivermectin may differ significantly between horse breeds, these differences do not affect the effectiveness of therapy., (© 2020 John Wiley & Sons Ltd.)

Tetracyclines continue to be important antimicrobials in veterinary medicine. However, the pharmacokinetics (PK) of tigecycline (TIG) and minocycline (MIN) in broiler chickens has not been investigated to date, and the PK of chlortetracycline (CTC) and tetracycline (TET) remains insufficiently researched, especially in terms of absorption. These antimicrobials have never been compared in a single setting in a single species; therefore, the aim of the present study was to compare the PK of TIG, MIN, CTC, and TET in broiler chickens. Each drug (10 mg/kg) was administered intravenously (IV) and orally (PO). The plasma concentrations of each drug were determined by liquid chromatography-tandem mass spectrometry, and the results were analyzed using compartmental and non-compartmental PK models. Despite the fact that all of the studied antimicrobials were administered at an identical IV dose, the area under the concentration-time curve between zero and the last sampling point (AUC 0→t ) for MIN (35,014 ± 3,274 μg × hour/mL) and CTC (41,851 ± 10,965 μg × hour/mL) differed significantly from that determined for TIG (18,866 ± 4,326 μg × hour/mL) and TET (17,817 ± 4,469 μg × hour/mL). After IV administration, the values of AUC 0→t were also directly related to total body clearance values which were significantly higher for TIG (0.56 ± 0.14 L/hour × kg) and TET (0.60 ± 0.14 L/hour × kg) than for CTC (0.25 ± 0.05 L/hour × kg) and MIN (0.29 ± 0.03 L/hour × kg). In turn, after PO administration, TIG was absorbed in only 1.55% ± 0.82, and CTC in 30.54% ± 6.99, whereas the bioavailability of MIN and TET was relatively high at 52.33% ± 3.92 and 56.45% ± 9.71, respectively. The differences in PK parameters between these drugs, despite their structural similarities, suggest that active transport mechanisms may play a role in their absorption and distribution., (Copyright © 2020. Published by Elsevier Inc.)

The main aims of this study were to determine whether CD4 + and CD8 + cells are present in the normal chambers of the eye in dogs and to verify the hypothesis that uncomplicated cataract may be associated with the local recruitment of CD4 + and CD8 + cells. The presence of CD4 + and CD8 + cells was detected in aqueous humor (AH) of normal and cataract eyes. The study did not reveal differences in the percentage and absolute number of CD4 + cells between normal and cataract eyes. However, the values of these parameters in AH from cataract eyes were approximately 2- and 3-fold higher than in normal eyes, respectively. The mean percentage and absolute count of CD8 + cells increased approximately by 2.7- and 6-fold, respectively, in AH samples from cataract eyes compared to normal ones. The absolute count of CD4 + and CD8 + cells in AH of uveitic eyes was approximately 5- and 3-fold higher than in cataract eyes. The results indicate that CD4 + and CD8 + cells occur constitutively in the normal chambers of the eye in dogs. However, it should be pointed out that both of these cell populations appeared in trace amounts. The development of uncomplicated cataract in dogs may not be immunologically neutral in terms of the local immune response, but it may be associated with the recruitment of CD8 + cells into the eye chambers. This event does not seem to be of an inflammatory nature because it appears on a scale a few times smaller than in the course of uveitis., Competing Interests: Declaration of Competing Interest The authors declare that they have no conflict of interests., (Copyright © 2020 Elsevier Ltd. All rights reserved.)

Background: The primary objective of this study was to develop a population pharmacokinetic model of meropenem, based on the population of critically ill adult patients undergoing CRRT. The secondary one was to examine the relationship between patient characteristics (covariates) and individual PK parameters. Finally, we aimed to perform Monte Carlo simulations to assess the probability of target attainment (PTA) of %T > MIC considering the uncertainty of PK parameters., Materials and Methods: The study population included 19 adult critically ill patients on CRRT, receiving 1 g of meropenem in 1-h infusions every 8 h. Blood samples were collected prior to (time zero) and 15, 30, 45, 60, 75, 90, 120, 180, 240 and 480 min after the start of meropenem administration. Population nonlinear mixed-effects modeling was conducted using NONMEM software, Fortran, and Wings for NONMEM., Results: A two-compartment model was used to describe the available data. Typical values of the central and peripheral volume of distribution, and the CRRT and inter-compartmental clearance for a theoretical patient with 24.6 g/l albumin concertation were V 1  = 27.9 l, V 2  = 33.7 l, Cl CRRT  = 15.1 l/h, and Q = 21.1 l/h. A significant covariate relationship between V 1 and albumin concentration was observed in the data that was described by a power relationship with - 2.87 exponent. Subsequently performed Monte Carlo simulations of the model allowed us to assess the impact of albumin concentration on PTA. The 40%T > 2 mg/l target was reached in more than 90% of subjects after 1-h infusion of 1000 mg q8h and steady-state conditions. The more stringent 100%T > 2 mg/l target requires higher doses and/or longer infusion durations that depend on the albumin concentration., Conclusions: The population PK model was successfully developed to describe the time course of meropenem concentrations. The hypoalbuminemia was found to be associated with higher PTA in the CRRT patients after multiple short-term infusions.

The aim of this study was to assess the adsorption of selected antibiotics: vancomycin, gentamicin, ciprofloxacine and tigecycline in an experimental continuous veno-venous hemofiltration circuit with the use of both polyethyleneimine-treated polyacrylonitrile (PAN) and the polysulfone (PS) filter membranes. The crystalloid fluid dosed with one of antibiotic was pumped from a reservoir through a hemofiltration circuit (with PAN or PS membrane) and back to reservoir. All ultrafiltrate was also returned to the reservoir. During the procedures samples were collected from the post-hemofilter port at 5, 15, 30, 45, 60, 90, and 120 min. To determine spontaneous degradation of the antimicrobials, an additional bag with each study drug was prepared, which was not attached to the hemofiltration circuit. The samples from these bags were used as controls. In the case of vancomycin, gentamycin and tigecycline there was a statistically significant decrease in the drug concentration in the hemofiltration circuit in comparison to the control for PAN membrane (P < 0.05, P < 0.001, P < 0.001, respectively). In the case of ciprofloxacine adsorption was reversible and the drug concentrations increase to achieve the initial level for both membranes. Our studies indicated that a large portion of the administered dose of antibiotics may be adsorbed on a PAN membrane. In the case of gentamicin and tigecycline this amount is sufficiently big (over 90% of the administered dose) to be of clinical importance. In turn, adsorption on PS membranes is clearly lower (up to 10%) and may be clinically unimportant.

Introduction: The first studies on the pharmacokinetics of ciprofloxacin during continuous renal replacement therapy were conducted using filters with a relatively small surface area and with lower intensity of the procedure than nowadays. The aim of this study was to assess the pharmacokinetics and the probability of achieving pharmacokinetic/pharmacodynamic (PK/PD) target for ciprofloxacin during renal replacement therapy using a filter with large surface area and higher intensity., Material and Methods: Eighteen patients were considered eligible for treatment with ciprofloxacin (400 mg every eight hours intravenously) during continuous renal replacement therapy. Blood samples were collected from the arterial line of the renal replacement circuit before (time 0) and after 30, 60, 75, 90, 120, 180, 240, and 480 minutes following the initiation of ciprofloxacin infusion. Ciprofloxacin concentrations in the collected samples were determined using fully validated liquid chromatography. The pharmacokinetic analysis was performed using non-compartmental analysis. The measure adopted to assess the efficacy of the antibiotic therapy was the proportion of patients for whom pre-defined PK/PD indices were achieved., Results: There was a considerable inter-individual variability observed in pharmacokinetic parameters for ciprofloxacin. 100% of patients achieved PK/PD target AUC0-24/MIC > 40, AUC0-24/MIC > 125, AUC0-24/MIC > 250 for MIC 1, 0.25, and 0.125 µg mL-1, respectively., Conclusions: High doses of ciprofloxacin (400 mg every eight hours intravenously) during continuous renal replacement therapy should be used to maximally increase the proportion of patients in whom clinical efficacy, expressed as achieving the PK/PD target, is reached.

The effect of constant light and constant darkness on intraocular pressure (IOP) in goats has not been investigated. We hypothesized that IOP variations would differ between goats kept under a cycle of 12 hours of light and 12 hours of darkness (LD), constant darkness (DD), and constant light (LL). To test this hypothesis, goats were exposed to these conditions for five days (LD, 30 goats; DD, 10 goats; LL, 10 goats). IOP was measured by applanation tonometry at 9 a.m. (beginning of photophase in LD) and 9 p.m. (beginning of scotophase in LD) on the fourth and fifth days of exposure. We found that changes in mean IOP from 9 a.m. to 9 p.m. differed significantly between groups (χ 2 (2) = 23.04, p < .0001). Most goats in LD showed a regular pattern of higher IOP in the morning and lower IOP in the evening, whereas those in DD and LL did not follow this pattern. In LD conditions, mean IOP was 2.4 mm Hg lower at 9 p.m. than at 9 a.m. (95% confidence interval for the difference (CI): -2.8 to -1.9 mm Hg, p < .0001). In DD conditions, mean IOP did not differ between 9 p.m. and 9 a.m. (CI: -0.9 to 0.8 mm Hg, p = .90). In LL conditions, it was 0.6 mm Hg lower at 9 p.m. (CI: -1.5 to 0.2 mm Hg, p = .12). Our results indicate that IOP in goats kept in LD is higher in the morning than in the evening, and that IOP variations are reduced in goats kept in DD and LL. These results suggest that exposure to alternating periods of light and darkness is important for maintaining rhythmic variations in IOP in this species.

Feline infectious peritonitis (FIP) is a serious, widely distributed systemic disease caused by feline coronavirus (FCoV), in which ocular disease is common. However, questions remain about the patterns of ocular inflammation and the distribution of viral antigen in the eyes of cats with FIP. This study characterized the ocular lesions of FIP including the expression of glial fibrillary acidic protein and proliferating cell nuclear antigen by Müller cells in the retina in cases of FIP and to what extent macrophages are involved in ocular inflammation in FIP. Immunohistochemistry for FCoV, CD3, CD79a, glial fibrillary acidic protein, calprotectin, and proliferating cell nuclear antigen was performed on paraffin sections from 15 naturally occurring cases of FIP and from controls. Glial fibrillary acidic protein expression was increased in the retina in cases of FIP. Müller cell proliferation was present within lesions of retinal detachment. Macrophages were present in FIP-associated ocular lesions, but they were the most numerous inflammatory cells only within granulomas (2/15 cats, 13%). In cases of severe inflammation of the ciliary body with damage to blood vessel walls and ciliary epithelium (3/15, 20%), some macrophages expressed FCoV antigens, and immunolabeling for calprotectin on consecutive sections suggested that these FCoV-positive macrophages were likely to be recently derived from blood. In cases of severe and massive inflammation of most ocular structures (4/15, 26%), B cells and plasma cells predominated over T cells and macrophages. These results indicate that gliosis can be present in FIP-affected retinas and suggest that breakdown of the blood-ocular barrier can allow FCoV-bearing macrophages to access the eye.

The aim of this study has been to determine whether eye chambers constitute part of the normal migratory pathway of naive CD4+ and CD8+ T cells in mouse and if natural CD4+CD25+Foxp3+ and CD8+CD25+Foxp3+ regulatory T cells are present within these eye compartments. To this aim, the cells obtained from aqueous humor (AH) of normal mice were phenotyped in terms of the expression CD4, CD8, CD25, CD127 and transcription factor Foxp3. The mean percentage of CD8+ T cells in the total AH lymphocyte population was as high as 28.69%; the mean percentage of CD8high and CD8low cells in this population was 34.09% and 65.91%, respectively. The presence of cells with the regulatory phenotype, i.e. CD25+Foxp3+ cells, constituted only 0.32% of CD8+ T cell subset. Regarding the expression of CD25, AH CD8+ T cells were an exceptional population in that nearly 85% of these cells expressed this molecule without concomitant Foxp3 expression. Despite having this phenotype, they should not be viewed as activated cells because most of them co-expressed CD127, which indicates that they are naive lymphocytes. With regard to the markers applied in the present research, CD8+CD25+CD127+Foxp3- T cells represent the most numerous subset of AH CD8+ cells. The results suggest that eye chambers in mice are an element in the normal migratory pathway of naive CD8+ T cells. The study presented herein demonstrated only trace presence of CD4+ cells in the eye chambers, as the mean percentage of these cells was just 0.56. Such selective and specific homing of CD8+ and CD4+ cells to the eye chambers is most clearly engaged in the induction and maintenance of ocular immune privilege., Competing Interests: The authors have declared that no competing interests exist.

The aim of this research was to determine whether prostaglandin E2 (PGE2) affects bovine NK cells in respect of their counts, apoptosis and proliferation, and if it does, then which of the PGE2 receptor (EP) subtype(s) mediate(s) these effects. We here report that long-term, but not short-term, exposure of bovine peripheral blood mononuclear cells to PGE2 at 10(-5)M, 10(-6)M and 10(-7)M, but not at 10(-8)M, caused a significant increase in the percentage of early apoptotic cells among NK cell subset. Moreover, PGE2 at 10(-5)M and 10(-6)M, but not at 10(-7)M and 10(-8)M, induced a considerable decrease in the absolute count of NK cells. The magnitude of these effects increased with an increasing concentration of PGE2. The blockade of EP1, EP2, EP3 and EP4 receptors did not prevent the PGE2-induced apoptosis and depletion of NK cells. The results suggest that the proapoptotic effect of PGE2 is secondary in character and the induction of this effect is not mediated through EP receptors. Furthermore, the studies demonstrated that PGE2 at 10(-5)M and 10(-6)M, but not at 10(-7)M and 10(-8)M, highly significantly reduced the percentage of proliferating NK cells. The EP1, EP1/2 and EP3 receptor antagonists were unable to block this effect significantly, whereas the selective blockade of EP4 receptors prevented the PGE2-induced inhibition of NK cells proliferation. These results indicate that PGE2 at certain concentrations may impair the proliferation of NK cells and this effect is mediated via the EP4 receptor., (Copyright © 2016 Elsevier Ltd. All rights reserved.)

The aim of these studies was to assess the influence of prostaglandin E2 (PGE2) on the production of interferon-gamma (IFN-γ) by bovine CD4(+), CD8(+), and WC1(+) T cells and furthermore, should this effect exist, to identify the E-prostanoid (EP) receptor subtype(s) responsible for this influence. We here report that exposure of bovine peripheral blood mononuclear cells (PBMCs) to PGE2 significantly and dose-dependently decreased the percentage of IFN-γ-producing CD4(+) and CD8(+) T cells. It was also shown that PGE2 reduced IFN-γ production by WC1(+) T cells, but this effect was not dose dependent. The impairment of IFN-γ production should be recognized as an anti-inflammatory and immunosuppressive action, thus the obtained results confirm the paradoxical status of PGE2 as a proinflammatory factor with immunosuppressive activity. The blockade of EP1, EP2, EP3, and EP4 receptors did not prevent PGE2-induced reduction of IFN-γ production by CD4(+) and CD8(+) T cells, indicating that this effect of PGE2 is not mediated through EP receptors. On the contrary, the blockade of either EP2 or EP4 receptors, but not EP1 or EP3 receptors, prevented the PGE2-induced reduction of percentage of IFN-γ-producing WC1(+) T cells. These findings indicate that the ability of PGE2 to impair IFN-γ production by WC1(+) T cells is mediated via EP2 and EP4 receptors. These results suggest the possibility of pharmacological manipulation of IFN-γ production by WC1(+) T cells via selective antagonists and agonists of EP2 and EP4 receptors., (Copyright © 2016 Elsevier Ltd. All rights reserved.)

The aim of this study was to determine the pharmacokinetics of oxytetracycline (OTC) in broiler chickens following intravenous (IV), intramuscular (IM), subcutaneous (SC) and oral (PO) administrations at a dose of 15 mg/kg bodyweight. Plasma concentrations of OTC were determined using liquid chromatography-tandem mass spectrometry and non-compartmental pharmacokinetic analysis was then conducted. The absorption half-life time was 1.23 ± 0.36 h, 1.19 ± 0.52 h, and 0.49 ± 0.38 h after IM, SC and PO administration, respectively. The elimination half-life time was 27.41 ± 6.06 h, 10.23 ± 4.20 h, 7.83 ± 0.56 h, and 14.86 ± 9.23 h, and the mean residence time was 9.67 ± 1.7 h, 11.45 ± 1.76 h, 11.38 ± 0.59 h, and 10.37 ± 3.91 h after IV, IM, SC and PO administration, respectively. Bioavailability was 76.88 ± 12.90%, 92.20 ± 10.53% and 12.13 ± 4.56% after IM, SC and PO administration, respectively, which indicated that OTC is poorly absorbed from the gastrointestinal tract in broiler chickens., (Copyright © 2015 Elsevier Ltd. All rights reserved.)

A crucial event in the initiation of an immune response is the activation of T cells, which requires IL-2 binding to its high-affinity IL-2 receptor for optimal signaling. The IL-2 receptor α-chain (CD25) is needed for the high affinity binding of IL-2 to effector cells and is potently induced after T cell activation. The aim of this research has been to determine whether prostaglandin E2 (PGE2) affects the CD25 expression on bovine T cells, and if it does, then which of the PGE2 receptor (EP) subtype(s) mediate(s) this effect. Herein, we report that exposure of peripheral blood mononuclear cells (PBMC) to PGE2 considerably reduces the percentage and absolute counts of CD25(+)CD4(+), CD25(+)CD8(+) and CD25(+)WC1(+) T cells, significantly increases the value of these parameters with respect of CD25(-)CD4(+), CD25(-)CD8(+) and CD25(-)WC1(+) T cells, and does not affect counts of the total populations of CD4(+), CD8(+) and WC1(+) T cells. These results indicate that PGE2 down-regulates the CD25 expression on bovine T cells. Moreover, we show that the selective blockade of EP4 receptor, but not EP1 and EP3 receptors, prevents this effect. Interestingly, the exposure of PBMC to a selective EP2 receptor agonist leads to a substantial increase in the percentage and absolute number of CD25(+)CD4(+), CD25(+)CD8(+) and CD25(+)WC1(+) T cells. In conclusions, the PGE2-induced down-regulation of CD25 expression on bovine CD4(+), CD8(+) and WC1(+) T cells should be considered as immunosuppressive and anti-inflammatory action, because these lymphocytes primarily represent effector cells and adequate CD25 expression is essential for their correct functioning. The PGE2-mediated down-regulation of the CD25 expression on bovine T cells is mediated via the EP4 receptor, although selective activation of the EP2 receptor up-regulates the CD25 expression on these cells. Thus, with respect to the effect of PGE2 on the CD25 expression on bovine T cells, EP4 receptor serves as an inhibitory receptor, whereas EP2 receptor functions as a stimulatory receptor. The fact that non-selective stimulation of EP receptors, i.e. triggered by PGE2, leads to weaker CD25 expression proves that inhibitory actions prevail over stimulatory ones. These results indicate the possibility of pharmacological manipulation of the CD25 expression on T cells via selective antagonists and agonists of EP2 and EP4 receptors., (Copyright © 2014 Elsevier B.V. All rights reserved.)

The objective of this study has been to determine the influence of food and ions on the pharmacokinetics of enrofloxacin (ENRO) in turkeys, administered per os at a dose of 10 mg/kg of body weight (b.w.). Co-administration of ENRO with ions or with food significantly retarded its absorption, and the interaction was more pronounced when the drug was given together with food. The bioavailability of ENRO was 65.78 ± 7.81% and 47.99 ± 9.48% with ions and food, respectively. The maximum concentration (Cmax) in plasma of animals exposed to ions reached 0.87 ± 0.26 μg/ml in a tmax of 2.07 ± 0.76 h; in animals which were fed while medicated, the analogous parameters were 0.36 ± 0.13 μg/ml and 8.06 ± 3.08 h. The PK/PD analysis demonstrated that a decrease in the concentration of ENRO in turkeys' blood due to the interaction with ions or food might impair the drug's clinical efficacy toward some pathogenic microorganisms in turkeys if a routine dose of 10 mg ENRO/kg b.w. is administered., (Copyright © 2014 Elsevier Ltd. All rights reserved.)

The aim of this study was to verify the values of maximal observed concentration (C max,obs) and the time, at which maximum concentration is observed (t max,obs) using the analysis of the absorption rate constant (k ab). It focused on the changes in concentration over time (C-T) for drugs, for which several peaks of concentration occur. In addition, the attempt was made to use Fibonacci sequence to facilitate the visual analysis of the dynamics in changes of concentration on C-T graphs. The analyses were conducted with the use of three hypothetical data groups (groups I, II and III), which had distinct C-T profiles, and with the in vivo data form healthy subjects (n = 10) taking part in a bioequivalence study, who was given a single oral dose of topiramate (100 mg). The comparison of hypothetical and real in vivo data demonstrated that for the C-T curves, in which there are several peaks of concentration C max,obs and t max,obs values can easily be miscalculated when the increase in concentration is not properly related to the appropriate absorption phase (63.2, 87.50, 96.88 %). It was also demonstrated that the data transformation with the use of Fibonacci sequence exposes slight differences in the observed concentration values in a semi-logarithmic scale. The results of this study show that in case of C-T curves with several peaks of concentration, the verification of C max and t max data obtained taking into account different absorption phases enables more precise evaluation of these parameters.

The aim of undertaken research was an in vitro evaluation of the effects of dexamethasone and meloxicam on selected bovine CD8(+) T lymphocyte subpopulations. Dexamethasone induced a fast-occurring and lasting depletion of CD25(-)CD8(+) cells. This was primarily the result of the proapoptotic effect of dexamethasone, but the antiproliferative effect of the drug was clearly responsible for the deepening of this disturbance. Dexamethasone transiently increased the relative and absolute CD25(high)CD8(+) and CD25(low)CD8(+) cell numbers. This effect was not a consequence of increased proliferation, but at least partly resulted from the antiapoptotic effect of the drug on these cells. The obtained results indicate that induction of CD8(+) lymphocyte depletion and impairment of IFN-γ production by these cells participate in the production of the anti-inflammatory and immunosuppressive effect of dexamethasone in cattle. An increase in Foxp3, IL-10 and TGF-β production by CD8(+) lymphocytes is not involved in the production of these effects because the drug did not affect the percentage of TGF-β(+)CD8(+) cells, while paradoxically reducing the percentage of cells with the suppressive phenotype, i.e. IL-10(+)CD25(low)CD8(+) and Foxp3(+)CD25(low)CD8(+) cells. Meloxicam did not substantially affect CD8(+) lymphocytes as to their percentage, absolute number, apoptosis, proliferation, Foxp3 expression and IFN-γ, IL-10 and TGF-β production. Thus, in the context of the parameters being estimated, meloxicam seems a relatively safe anti-inflammatory drug to be used in infectious diseases in cattle., (Copyright © 2012 Elsevier Ltd. All rights reserved.)

WC1+ cells in cattle exhibit both regulatory and effector activities. However, it has not been elucidated whether they are so plastic that both activities co-exist in one cell or there are separate subpopulations of effector and regulatory cells. Since the production of IFN-gamma and IL-10 seems to be related to WC1+ cells' effector and regulatory function, respectively, the main aim of this study was to determine whether those cytokines are produced by separate subpopulations of WC1+, or are co-produced by the same cells. Due to increasingly frequent emphasised role of consumption of IL-2 in the mechanism of suppressor action of mouse CD25+CD4+ T regulatory cells, expression of the receptor's alpha chain for interleukin 2 (CD25) on WC1+ lymphocytes has been evaluated. An average of 5.21% of WC1+ cells obtained from PBMCs of 12-month-old heifers show constitutive expression of the CD25 molecule, with CD25(high)WC1+ and CD25(low)WC1+ cells accounting for 1.05% and 4.10% of WC1+ lymphocytes, respectively. For detection of intracellular cytokine production, PBMCs were stimulated with concanavalin A. Both IFN-gamma(-) and IL-10-producing cells within the CD25(-)WC1+ and CD25+WC1+ subpopulations were mainly separate subpopulations. The average percentage of IFN-gamma(+)IL-10(-), IFN-gamma(-)IL-10+ and IFN-gamma(+)IL-10+ cells among CD25(-)WC1+ lymphocytes was 4.03%, 2.67% and 0.51%, respectively. A positive correlation was observed between the presence of the CD25 molecule on WC1+ lymphocytes and production of IL-10 and TGF-beta, because the average percentage of IFN-gamma(-)IL-10+ and IFN-gamma(+)IL-10+ among CD25+WC1+ lymphocytes was 3 and 4.5 times higher as compared to the corresponding cells in the CD25(-)WC1+ subpopulation, whereas the percentage of IFN-gamma(+)IL-10(-) cells in both the subpopulations was not significantly different. The percentage of TGF-beta+ cells within the CD25+WC1+ subpopulation was 2.72 times as high as that of CD25(-)WC1+ lymphocytes. Therefore, with respect to the production of IFN-gamma, IL-10 and TGF-beta, CD25+WC1+ lymphocytes turn out to have a more suppressor profile than CD25(-)WC1+.

Methods for determination of albendazole (ALB), albendazole sulfoxide (SOX) and albendazole sulfone (SON) in turkey blood plasma, using high-performance liquid chromatography (HPLC) with fluorescence detection, were developed. Moreover, comparison of HPLC columns with ultra-performance liquid chromatography (UPLC) columns was performed. Albendazol was administered orally in 5-week-old birds (n = 18) at a dose of 25 mg/kg b.w. Accuracy and precision of the developed method were satisfactory and stability studies showed acceptable variation (below 15%) in ALB, SOX and SON concentrations when the samples were stored at -75°C for 15 days. UPLC(®) columns gave higher peaks from typical HPLC columns retaining high quality of analysis. Pharmacokinetic analysis indicated quick elimination of ALB from turkey blood plasma. The mean residence time of SON was at least two times longer than that of SOX and four times longer than that of ALB. The elimination half-lives for ALB, SOX and SON were 0.7 ± 0.27, 5.37 ± 6.03, 9.17 ± 5.12 h, respectively. The obtained results indicate that the described method allows for precise determination of albendazole and its metabolites in turkey plasma. Moreover, using UPLC columns in HPLC apparatus results in higher sensitivity as compared with the classical HPLC columns., (Copyright © 2011 John Wiley & Sons, Ltd.)