Pharmacokinetic-pharmacodynamic integration of danofloxacin after intravenous, intramuscular and subcutaneous administration to rabbits

The pharmacokinetics of danofloxacin was studied following intravenous (i.v.), intramuscular (i.m.) and subcutaneous (s.c.) administration of 6 mg/kg to healthy rabbits. Danofloxacin concentration were determined by high-performance liquid chromatography assay with fluorescence detection. Minimal inhibitory concentrations (MICs) assay of danofloxacin against 30 strains of Staphylococcus aureus from several European countries was performed in order to compute pharmacodynamic surrogate markers. The danofloxacin plasma concentration versus time data after i.v. administration could best be described by a two-compartment open model. The disposition of i.m. and subcutaneously administered danofloxacin was best described by a one-compartment model. The terminal half-life for i.v., i.m. and s.c. routes was 4.88, 6.70 and 8.20 h, respectively. Clearance value after i.v. dosing was 0.76 L/kg.h. After i.m. administration, the absolute bioavailability was mean (+/-SD) 102.34 +/- 5.17% and the Cmax was 1.87 mg/L. After s.c. administration, the absolute bioavailability was mean (+/-SD) 96.44 +/- 5.95% and the Cmax was 1.79 mg/L. Danofloxacin shows a favourable pharmacokinetics profile in rabbits reflected by parameters such as a long half-life and a high bioavailability. However, in consideration of the low AUC/MIC indices obtained, its use by i.m. and s.c. route against the S. aureus strains assayed in this study cannot be recommended given the risk for selection of first mutant subpopulations.     

Cetirizine in horses: pharmacokinetics and effect of ivermectin pretreatment

The pharmacokinetics of the histamine H(1)-antagonist cetirizine and the effects of pretreatment with the antiparasitic macrocyclic lactone ivermectin on the pharmacokinetics of cetirizine were studied in horses. After oral administration of cetirizine at 0.2 mg/kg bw, the mean terminal half-life was 3.4 h (range 2.9-3.7 h) and the maximal plasma concentration 132 ng/mL (101-196 ng/mL). The time to reach maximal plasma concentration was 0.7 h (0.5-0.8 h). Ivermectin (0.2 mg/kg bw) given orally 1.5 h before cetirizine did not affect its pharmacokinetics. However, ivermectin pretreatment 12 h before cetirizine increased the area under the plasma concentration-time curve by 60%. The maximal plasma concentration, terminal half-life and mean residence time also increased significantly following the 12 h pretreatment. Ivermectin is an inhibitor of P-glycoprotein, which is a major drug efflux transporter in cellular membranes at various sites. The elevated plasma levels of cetirizine following the pretreatment with ivermectin may mainly be due to decreased renal secretion, related to inhibition of the P-glycoprotein in the proximal tubular cells of the kidney. The pharmacokinetic properties of cetirizine have characteristics which are suitable for an antihistamine, and this substance may be a useful drug in horses.     

Death of a horse infected experimentally with Anaplasma phagocytophilum

A 19-year-old horse that was one of a group of six horses infected experimentally with Anaplasma phagocytophilum for a study of the pathogenesis of equine granulocytic ehrlichiosis died suddenly two days after first showing clinical signs of disease. The clinical signs and laboratory findings observed before its death were similar to all those of the other infected horses, and to previous reports of this disease. A postmortem examination revealed widespread haemorrhaging in its internal organs, and vasculitis and thrombosis in the kidneys. These changes are consistent with disseminated intravascular coagulation, which has previously been reported in human beings infected with the presumably identical agent of human granulocytic ehrlichiosis.     

Semen alterations in porcine rubulavirus-infected boars are related to viral excretion and have implications for artificial insemination

Porcine rubulavirus (PoRV), also known as blue eye disease (BED) of swine, causes respiratory and reproductive problems in pigs at several developmental stages. To study the effect of PoRV infection on semen production, five boars were infected with 1 x 10(6) TCID(50)/ml of PoRV strain PAC-3 and evaluated for 59 days post inoculation (DPI). Infected boars developed reproductive tract pathology that included swelling of the testes and epididymides. Analysis of the semen showed that the infection had little effect on semen production in four animals, but semen from one boar showed severe alterations in sperm concentration, motility, and morphology. When motility was analyzed in BTS-diluted semen after 24, 48, or 72 h, alterations were detected in all boars. Furthermore, viral antigen was detected in semen, the seminal plasma fraction, or sperm fraction from all boars. These results showed that PoRV is excreted via semen and, therefore, artificial insemination is a potential route of dissemination.     

Activities of biotransformation enzymes in pheasant (Phasianus colchicus) and their modulation by in vivo administration of mebendazole and flubendazole

Basal activities of certain pheasant hepatic and intestinal biotransformation enzymes and modulation of their activities by anthelmintics flubendazole (FLBZ) and mebendazole (MBZ) were investigated in subcellular fractions that were prepared from liver and small intestine of control and FLBZ or MBZ treated birds. Several oxidation, reduction and conjugation enzyme activities were assessed. In the liver, treatment of pheasants by FLBZ or MBZ caused very slight or no changes in monooxygenase activities and conjugation enzymes. More significative changes were detected in small intestine. Metyrapone and daunorubicin reductase activities were increased by both substances in the liver. This is the first evidence that certain benzimidazoles modulate reductases of carbonyl group. With respect to the relatively slight extent of the changes caused by FLBZ or MBZ we can assume that repeated administration of therapeutic doses of both FLBZ and MBZ has probably no serious influence on pheasant biotransformation enzyme system.     

Host/parasite relationship in the in vitro infection of rat gliocytes by Neospora caninum: evaluation of cell respiration

Neospora caninum is a protozoon that causes abortion in cattle and neuromuscular lesions in dogs, with the formation of cysts mainly in the central nervous system. Since N. caninum is an intracellular parasite with tropism for the cells of nervous system, this study evaluated the respiratory metabolism of glial cells infected by this* parasite. Glial cultures obtained from the cerebral cortex of newborn rats were kept in DMEM enriched with 10% fetal bovine serum, 1 mM pyruvic acid and 2 mM of L-glutamine. They were infected at a ratio of approximately 1:1 (cell/parasite). Oxygen consumption was evaluated by polarography in the non infected and N. caninum infected groups, 24 and 72 h following infection. Glial cell respiration after 24 and 72 h was 307.2 +/- 34.7 and 308.9 +/- 64.1 microL of oxygen per mug of total protein per minute, and 566.2 +/- 54.6 and 579 +/- 117.5 microL O2/microg of total protein/minute in the control and infected groups, respectively. These results show that N. caninum does not interfere with glial respiration in vitro.     

Isolation of Lawsonia intracellularis specific single-chain Fv antibody fragments from phage display library

Single-chain antibodies (scFv) exhibiting specific binding to Lawsonia intracellularis were isolated from a phagemid library expressing scFvs molecules on the surface of filamentous bacteriophages. For scFv selection whole bacterial cells were used and individual clones were tested in ELISA test. The total of seven unique clones with different fingerprint profiles was isolated. All clones were able to bind specifically in immunofluorescence assay. This is the first report of species specific recombinant antibodies against L. intracellularis.     

An immunohistochemical study of the tonsils in pigs with acute African swine fever virus infection

An immunohistochemical study of the tonsils was carried out to gain further insight in the pathogenesis of acute African swine fever (ASF). Twenty-one pigs were inoculated by intramuscular route with a highly virulent isolate of ASF virus and painlessly killed at 1-7dpi. Viral antigen was highly distributed in the tonsil from 3 to 4dpi and an increase in the number of monocyte-macrophages was very evident at the same days post inoculation. This phenomenon was observed together with an increase of the expression of proinflammatory cytokines (Tumour necrosis factor alpha and Interleukin-1 alpha) and the apoptosis of lymphocytes studied by the terminal deoxynucleotidyltransferase-mediated dUTP nick end labelling (TUNEL) technique and haemorrhages. With these results, we can conclude that the tonsil is suffering similar lesions than those observed in other lymphoid organs in acute African swine fever, even when the route of inoculation is the intramuscular and not oral-nasal.     

Suitability of electronic mini-boluses for early identification of lambs

Three types of ceramic mini-boluses, B1 [13.8 g; 10.5 x 51.0 mm (o.d. x length)], B2 (16.2 g; 12.2 x 42.2 mm), and B3 (20.1 g; 11.2 x 56.4 mm), were used to electronically identify as soon as possible after birth a total of 545 lambs of 3 breeds: Ripollesa (meat breed, n = 274), Manchega (dairy breed, n = 129), and Lacaune (dairy breed, n = 142). Boluses were administered by a trained operator using a balling gun or directly by hand. Lambs were also identified with 2 types of plastic ear tags in the left (temporary, 1.5 g) and the right (permanent, 4.1 g) ears. Lamb and identification device performances were checked during suckling (to wk 5 or 7) and fattening. At 24 kg of BW, lambs were slaughtered (n = 385) or kept for breeding (n = 144). No differences in performance were observed between the 2 dairy breeds, and their data were pooled. Minimum BW for bolus administration was lower in dairy than in meat lambs (P < 0.001). Across breeds, B1 and B3 did not differ in lamb age (27 d) and weight (9.2 kg) at administration, but B2 required older and heavier lambs (33 d and 11.1 kg; P < 0.01). Boluses did not affect lamb performance, but final readability at slaughter differed between B1 and B2 (97.7 and 95.2%, respectively) and B3 (100%), and between ear tags (temporary, 98.1; permanent, 100%). Bolus recovery was 100% in all cases, but the proportion of boluses found in the reticulum varied among bolus type (83.3 to 93.8%; P < 0.05). Three B1 (2%) were recovered from the abomasum. In a second experiment, effects of the intermediate mini-bolus (B2) on diet digestibility were evaluated. Digestibility of control and bolus-administered, Manchega ram lambs (14.9 kg of BW; n = 8) fed ad libitum with 2 pelleted concentrates and barley straw was assessed in digestibility crates. Feed intake and nutrient digestibility were measured in four 21-d periods, during which lambs received the 2 diets consecutively. No differences in intake, growth performance, or nutrient digestibility were observed between control and bolused lambs. In conclusion, the B3 mini-bolus proved to be an efficient device for identification of lambs before weaning (recommended age, >4 wk; recommended BW, >10 kg), allowing a reliable traceability of dairy and meat lambs until slaughter.     

Leishmania-specific isotype levels and their relationship with specific cell-mediated immunity parameters in canine leishmaniasis

In the current retrospective study, Leishmania infantum-specific IgG, IgA and IgM levels were determined by ELISA in 106 untreated dogs with clinically-patent leishmaniasis (Sx) and in 171 clinically healthy dogs (Asx) from Spain to investigate the relationship between these Ig isotypes and clinical status. In addition, we studied if different Leishmania-specific humoral pattern exists between Asx dogs with and without cellular mediated immunity (CMI). Fifty-six dogs were assessed by means of lymphoproliferation assay (LPA), interferon production (IFN) and leishmanin skin test (LST), 71 dogs by means of both LPA and IFN and 44 only by LST. Both Sx and Asx dogs produced Leishmania-specific IgG, IgA and IgM antibodies, however the levels and proportion of positive dogs for each Ig isotype were significantly higher in Sx than in Asx ones (P<0.001). Analysis of immunological profiles determined for each cellular technique (positive and negative cellular response for each technique combined with positive or negative specific humoral response) showed that Asx dogs constituted a high heterogeneous group. No correlations were observed between CMI tests and specific IgG or IgM levels. However, a significant inverse correlation was demonstrated between specific IgA levels and LPA response (Spearman's r=-0.220; P=0.035). In general, the low correlation detected between CMI tests and isotype levels might indicate that the immune response is not strongly polarized in the majority of Asx dogs. Additionally, this study suggests that dogs developing T-cell response are probably able to avoid the dissemination of the parasite at least to mucosal surfaces and, as a consequence, to produce low or background specific IgA levels. Further studies are needed to investigate the relationship between specific IgA and parasite load, especially at mucosal site.