Pharmacokinetics and bioavailability of spiramycin in pigs.

The pharmacokinetics of spiramycin in pigs were investigated after intravenous and oral administration. The potential therapeutically effective blood level was established after a single administration and examined in a subsidiary five day study. The rapid intravenous injection of 25 mg spiramycin/kg bodyweight produced marked salivation in all the test animals. The elimination half-life (2.3 +/- 1.2 hours) was relatively short, in accordance with the total body clearance rate (27.3 +/- 10.1 ml/minute/kg). The high volume of distribution (5.2 +/- 2.2 litres/kg) was due to the accumulation of the drug in the body tissues. The maximum plasma concentration (4.1 +/- 1.7 micrograms/ml) after oral administration of 85 to 100 mg spiramycin/kg bodyweight was reached after 3.7 +/- 0.8 hours and the half-life of the elimination phase was 6.0 +/- 2.4 hours. The oral bioavailability was 45.4 +/- 23.4 per cent. Ad libitum feeding of a diet containing 2550 mg spiramycin/kg produced a steady state concentration of 0.96 +/- 0.27 micrograms/ml. This plasma concentration would provide a potentially therapeutically effective blood concentration against Mycoplasma species, Streptococcus species and Staphylococcus species.     

The Nebraska Veterinary Medical Association antidote depot

The Nebraska Veterinary Medical Association provided financial assistance to establish an antidote depot system statewide at the 3 University of Nebraska veterinary diagnostic laboratories located in Lincoln, North Platte, and Mitchell. The depot system currently stocks atropine sulfate, methylene blue, activated charcoal, dimercaprol, and EDTA. Antidotes are available to all Nebraska veterinarians. Depot withdrawals are used for emergency treatment only and not for a convenient source of supply to replenish individual inventory. The depot system was designed to assist veterinary practitioners in treating toxicoses during catastrophic occurrences in which available inventories have been exhausted. Since time is of essence in most toxicoses, withdrawals from depot sites normally are made by veterinarians or their authorized representatives. There are no fees for using the depot system, but patrons are required to replace drugs at the specific storage site on an item-for-item basis, in like amount, and at current unit cost. Items are issued and replaced only as intact units.     

A survey of the causes of mortality in adult mink, with emphasis on the lactation period

A study of the pattern and relative frequency of diseases in adult female mink during the lactation period was undertaken. All adult females that died between parturition (April/May) and July 1, 1990, from 48 farms in southern Ontario were selected for study, and the cause of death was determined by gross necropsy. In addition, the cause of death was determined by gross necropsy for all adults and weaned kits that died on one farm between April 1988 and March 1989.

The mortality rate among farms in the 1990 study, for adult females during the lactation period, ranged from 0.2% to 10.1%, with a median of 1.9%. Nursing disease (56%) was the most common diagnosis, followed by mastitis (11%), metritis (8%), and dystocia (7%). Escherichia coli and Staphylococcus spp. were the most frequent isolates from the cases of mastitis. In the 1988/1989 study, the mortality rate was highest from May to July, with a large increase in June as a result of nursing disease.

     

Histology of two rice bodies isolated from the stifle of an adult draught horse stallion

In the human and equine species, different kinds of free floating intra-articular particles are related to certain disorders. Osteochondral fragments formed during osteochondrosis dissecans are the most common finding in the equine species, whereas in humans rice bodies due to rheumatoid arthritis are more frequent. Herein we report a third type of floating body inside the stifle of an adult draught horse stallion, in macroscopic appearance similar to articular rice bodies known in humans. As revealed by histologic examination, the two particles consist of polypoid degenerated structures derived from synovial villi. Their formation was probably induced by ischemia.     

Alteration of reproductive hormone levels in pregnant sows induced by repeated ACTH application and its possible influence on pre- and post-natal hormone secretion of piglets

Prenatal stress has been seen as a reason for reproductive failures in pig offspring mostly originated or mediated by changed maternal functions. Experiments were conducted in pregnant gilts (n=32) to characterize effects of elevated maternal glucocorticoids on the secretion of reproductive hormones (LH, progesterone) during the 1st (EXP 1), 2nd (EXP 2) and 3rd (EXP 3) trimester of pregnancy (TP). Transiently elevated cortisol release was repeatedly achieved by application of 100 IU adenocorticotropic hormone (ACTH) (Synacthen Depot) six times every second day beginning either on day 28 (EXP 1), day 49 (EXP 2) or day 75 of pregnancy (EXP 3). Glucocorticoid concentrations were examined in umbilical blood vessels of fetuses which mothers were subjected to ACTH at 2nd and 3rd TP (EXP 4). Furthermore, the pituitary function of newborn piglets of EXP 2 was checked by a LH-RH challenge test. In sows, LH concentrations were at low basal level (0.1-0.2 ng/ml) but with pulsatory release pattern during each TP. The number of LH pulses/6 h (LSM +/- SE) of saline treated Controls increased with ongoing pregnancy and decreased to the 3rd TP (1.3 +/- 0.2 in EXP 1 vs. 2.0 +/- 0.1 in EXP 2 vs. 1.4 +/- 0.1 in EXP 3, p<0.05). After ACTH treatment the number of LH pulses left unchanged in Experiments 1 and 2 (1.3 +/- 0.2 and 1.5 +/- 0.1) and decreased in EXP 3 (0.8 +/- 0.2, p<0.05). Differences (p<0.05) were obtained comparing the LH pulse number of ACTH and saline treated sows at the 2nd and 3rd TP. Moreover, areas under the curve (AUC) of each LH pulse and of LH over baseline were significantly reduced by treatment. Levels of progesterone increased (p<0.05) for 150 to 170 min after each ACTH application both in EXP 1 and EXP 2, but not in EXP 3. The mean progesterone concentration was different between trimesters, and ACTH and Controls (1st TP: 30.0 +/- 0.9 and 24.4 +/- 0.7 ng/ml; 2nd TP: 35.5 +/- 0.9 and 29.1 +/- 1.0 ng/ml; 3rd TP: 13.6 +/- 0.2 and 13.1 +/- 0.1 ng/ml; p<0.05). In fetuses (n=87) recovered 3 h after ACTH or saline (EXP 4), the plasma cortisol concentrations were significantly increased in umbilical vein (93.7 +/- 5.5 vs. 47.0 +/- 5.3 nmol/l) and artery (95.7 +/- 5.4 vs. 66.4 +/- 5.4 nmol/l), and in periphery (46.8 +/- 5.3 vs. 27.1 +/- 5.3 nmol/l) compared to controls. Plasma ACTH concentrations, however, did not differ in fetuses of both treatment groups. Postnatal LH-RH challenge tests (1st and 28th day post partum) induced LH surges in female piglets (n=67) both of ACTH and saline treated sows, but did not differ between groups (1st day: 7.2 +/- 0.8 vs. 8.1 +/- 0.7 ng/ml; 28th day: 10.5 +/- 1.7 vs. 13.6 +/- 2.2 ng/ml). However, basal LH of piglets whose mothers were submitted to ACTH during 2nd TP was lower on 1st day (1.7 +/- 0.2 vs. 2.3 +/- 0.2 ng/ml, p<0.05) but not on 28th day (1.0 +/- 0.2 vs. 1.1 +/- 0.2 ng/ml). However in both groups, the basal LH was always higher on 1st as on 28th day (p<0.05). Thus, chronic intermittent ACTH administration is able to influence the release pattern of maternal reproductive hormones. However, these findings demonstrate that these effects are dependent on the stage of pregnancy. Furthermore, it was shown that maternal cortisol can cross the placenta during gestation and thus may affect maternal-fetal interactions and, as a result, reproductive function of offspring.     

Cloning and expression of pigeon IFN-γ gene

This is the first paper describing the cloning of pigeon IFN-γ gene (PiIFN-γ) and the analysis of the in vitro expressed recombinant protein. The PiIFN-γ gene was identified by RT-PCR as a 498 bp, fragment coding for a precursor protein of 165 amino acids instead of 164 amino acids, as observed in the other avian species. The recombinant protein was expressed in vitro by an eukaryotic system and the biological properties of the cytokine were tested using a chicken macrophage cell line. The high degree of amino acid and nucleotide identity, shared with the ChIFN-γ, and the fact that the pigeon protein was functional on chicken cells, indicates a cross-reactivity between pigeon and chicken IFN-γ. The detection of the PiIFN-γ could represent an useful instrument in understanding the role played by this cytokine in immune response related to vaccinations and infectious diseases in the pigeon.     

Palmar digital vessel relaxation in healthy horses and in horses given carbohydrate

OBJECTIVE: To compare in vitro smooth muscle relaxation of palmar digital vessels from healthy horses with those from horses in the prodromal stage of experimentally (carbohydrate) induced laminitis. ANIMALS: 16 adult horses. PROCEDURE: Segments of palmar digital vessels were obtained from 5 healthy horses and 6 horses given carbohydrate. Vascular rings from the palmar digital artery and vein were suspended in individual organ baths containing buffer solution and indomethacin; isometric tension was recorded, and contraction and relaxation were compared. Smooth muscle contraction in response to cumulative addition of phenylephrine was recorded in the absence and presence of 1 microM NG-nitro-L-arginine methyl ester (L -NAME). After wash out, vascular rings were preconstricted with phenylephrine (0.3 microM), and cumulative endothelium-dependent (acetylcholine-induced) and independent (nitroprusside-induced) smooth muscle relaxations were recorded in the absence or presence of L -NAME. RESULTS: Phenylephrine increased vascular smooth muscle tone in ring preparations of palmar digital arteries and veins. Addition of acetylcholine or nitroprusside induced relaxation of palmar digital artery and vein ring preparations. Use of L-NAME (1 microM) significantly reduced maximal relaxation induced by acetylcholine, but not by nitroprusside. Maximal relaxation induced by acetylcholine, but not by nitroprusside, was reduced in vascular rings prepared from carbohydrate-overloaded horses. CONCLUSION AND CLINICAL RELEVANCE: Reduced endothelium-dependent relaxation of palmar digital vessels may have a role in the pathophysiology of acute laminitis after carbohydrate overload in horses.     

Detection of Mycobacterium avium ssp. paratuberculosis in ileocaecal lymph nodes collected from elderly slaughter cows using a semi-nested IS900 polymerase chain reaction

The aim of this study was to investigate the occurrence of subclinical Mycobacterium avium spp. paratuberculosis (MAP) infections at slaughter by testing ileocaecal lymph nodes with a semi-nested IS900 PCR. Tissue samples were available within the framework of a parallel study investigating BSE-susceptibility factors in members of BSE-cohorts in the German Federal State of Lower Saxony. Ileocaecal lymph nodes were collected over a 2-year sampling period from 99 slaughter cattle of a mean age of 6.5 years (5.5-7.5 years). A recently developed IS900 semi-nested polymerase chain reaction (snPCR) assay offering a sensitivity of 1 genome equivalent was used for the detection of MAP-DNA. Based on this snPCR, 17 out of the 99 samples gave positive results, indicating a MAP occurrence of 17.17% in the random sample. All PCR products were sequenced for screening of polymorphisms. Nucleotide homologies of 98.5-100% were found with respect to the MAP K10 reference sequence IS900 (GenBank: AE16958). PCR analysis of ileocaecal lymph nodes collected from slaughter cattle proved to be a suitable technique to determine MAP occurrence in the local cattle population.     

Exogenous paraoxonase‐1 during oocyte maturation improves bovine embryo development in vitro

Paraoxonase‐1 (PON1) is an enzyme found in serum and follicular fluid that protects cell membrane and circulating lipids against oxidative damage. The aims of this study were to measure the direct effects of recombinant PON1 (rPON1) on bovine oocyte maturation at the molecular level (gene expression) and to measure the carry‐over effects of PON1 on pre‐implantation embryo development in vitro. COCs were submitted to IVM with the addition of 0.0, 0.02, 0.04 and 0.08 mg ml^?1 of rPON1, corresponding to an average PON1 arylesterase enzyme activity of 2.2 ± 0.4, 15.5 ± 1.5, 30.2 ± 3.0 and 57.9 ± 5.0 U ml^?1, respectively. The results indicated that addition of rPON1 during IVM improved embryo development in a dose‐dependent manner as D7 embryo development was 22.2%, 29.4%, 32.2% and 37.0% for the treatment groups, respectively (p = 0.02). In conclusion, addition of PON1 enzyme during IVM exerted dose‐related positive effects on embryo development rates to blastocysts.