Literarische Berichte

Ohne Zusammenfassung     

Ocular distribution and toxicity of intravitreal injection of triamcinolone acetonide in normal equine eyes

Objective  To determine ocular distribution and toxicity of a single injection of intravitreal triamcinolone acetonide (TA) in normal horses.
Animals studied  Six adult horses, donated to North Carolina State University.
Procedures  Six horses were injected intravitreally with either 10, 20, or 40 mg ( n  = 2 each) of TA. The opposite eye of each horse was injected with balanced salt solution (BSS). Ocular toxicity was assessed by biomicroscopy, tonometry, indirect ophthalmoscopy, and electroretinogram. Aqueous humor (AH), vitreous humor (VH), and plasma samples were collected. Horses were euthanized 7 or 21 days after injection and eyes enucleated for histopathology. TA concentrations in AH, VH, and plasma were measured by HPLC.
Results  Three control eyes and one TA eye developed inflammation after injection or collection of AH. Positive bacterial cultures ( Corynebacterium spp., Staphylococcus spp., and Streptococcus spp.) were obtained from three of these eyes. Other than transient corneal edema in TA injected eyes, which resolved by 7 days after injection, no other changes were observed. TA crystals were visible within the vitreous body. No evidence of TA toxic effect was noted on histopathology. TA was detected in all AH and VH samples from treated eyes following injection. Drug was not detected in the plasma.
Conclusions  There was no evidence of overt toxicity from intravitreal TA in normal horses and a single intravitreal injection resulted in TA ocular levels for 21 days. However, the risk for bacterial infections with intravitreal injection or anterior chamber aspirations in horses is high. Use of topical and systemic antibiotics after injection is recommended.     

Combined effects of clenbuterol and various concentrations of protein on performance of broiler chickens

1. The effects of the beta-adrenergic agonist, clenbuterol (1 mg/kg diet) on the growth and muscle composition in female broiler chickens (14 to 32 d of age) fed on diets containing various concentrations of protein (220, 240 or 260 g protein/kg) were examined. 2. Body weight gain over the 18 d period increased linearly with increasing protein intake. The rate of gain was significantly higher in clenbuterol-treated chickens than in control birds. 3. Dietary clenbuterol increased thigh muscle weight and protein concentration of breast and thigh muscle, regardless of dietary protein content. Protein/DNA ratio in thigh muscle was enhanced by clenbuterol feeding, and the magnitude of difference of the ratio was higher in chickens fed on the 240 and 260 g CP/kg diets than in those fed the 220 g CP/kg diet. 4. It was concluded that clenbuterol-treated chickens require increased dietary protein to maintain maximal growth, and that increased protein consumption is an important factor in improving growth in clenbuterolfed broilers.     

A new hemolytic assay for bovine serum complement and its application during experimental bovine anaplasmosis

A new hemolytic assay for bovine complement is presented. Using this assay we found a significant reduction in bovine serum complement activity during the acute phase of anaplasmosis, and an increase in the sensitivity of the red blood cells (RBC) to bovine complement lysis in vitro. The new hemolytic test is performed with bovine RBC, rabbit anti-bovine RBC serum and bovine serum complement. An isotonic sucrose Tris-buffered saline solution of ionic strength 0.094 and pH 7.2 was found to be adequate for this test. The titres obtained with this new assay, which uses autologous RBC, are comparable with those obtained using the guinea pig RBC assay. The finding of a reduction in bovine serum complement during anaplasmosis may be suggestive of a mechanism responsible for the pathology of this disease.     

Pharmacokinetics of penicillin G procaine versus penicillin G potassium and procaine hydrochloride in horses

OBJECTIVE: To compare the pharmacokinetics of penicillin G and procaine in racehorses following i.m. administration of penicillin G procaine (PGP) with pharmacokinetics following i.m. administration of penicillin G potassium and procaine hydrochloride (PH). ANIMALS: 6 healthy adult mares. PROCEDURE: Horses were treated with PGP (22,000 units of penicillin G/kg of body weight, i.m.) and with penicillin G potassium (22,000 U/kg, i.m.) and PH (1.55 mg/kg, i.m.). A minimum of 3 weeks was allowed to elapse between drug treatments. Plasma and urine penicillin G and procaine concentrations were measured by use of high-pressure liquid chromatography. RESULTS: Median elimination phase half-lives of penicillin G were 24.7 and 12.9 hours, respectively, after administration of PGP and penicillin G potassium. Plasma penicillin G concentration 24 hours after administration of penicillin G potassium and PH was not significantly different from concentration 24 hours after administration of PGP. Median elimination phase half-life of procaine following administration of PGP (15.6 hours) was significantly longer than value obtained after administration of penicillin G potassium and PH (1 hour). CONCLUSIONS AND CLINICAL RELEVANCE: Results suggest that i.m. administration of penicillin G potassium will result in plasma penicillin G concentrations for 24 hours after drug administration comparable to those obtained with administration of PGP Clearance of procaine from plasma following administration of penicillin G potassium and PH was rapid, compared with clearance following administration of PGP.     

Disease-induced alterations in plasma drug-binding proteins and their influence on drug binding percentages in dogs

Disease-induced variations of plasma albumin (ALB) and alpha 1-acid glycoprotein (AAG) levels were investigated in dogs. Lower ALB (sometimes > 50% reduction) and higher AAG (sometimes > 10-fold increase) levels were observed in dogs with various diseases. Drug binding was determined at therapeutic concentrations using normal, low-ALB and high-AAG dog plasma. The binding percentages of the ALB-binding drugs decreased in low-ALB plasma, resulting in a large increase in unbound drug, particularly for naproxen (a 13-fold increase). The binding percentages of all AAG-binding drugs investigated in this study increased in high-AAG plasma, resulting in a large decrease in unbound drug, particularly for quinidine (99% decrease). The fluctuation in the unbound fraction of drugs could affect their efficacy or could cause side-effects. Veterinary clinicians should monitor the ALB and AAG levels in the plasma of patients and correct dosage regimens according to these levels, where field conditions permit this, in order to ensure the proper usage of drugs with high affinity for ALB or AAG.     

Technical note: recombinant LHRH fusion protein suppresses estrus in heifers

A recombinant luteinizing hormone-releasing hormone (LHRH) fusion protein was evaluated for its effectiveness in suppression of estrus in heifers. Eight heifers were randomly assigned to two equal treatment groups. Treatments consisted of recombinant ovalbumin-LHRH-7 or recombinant ovalbumin (control). This recombinant chimeric fusion protein consisted of ovalbumin with seven LHRH peptides (ovalbumin-LHRH-7). The plasmid for this protein was expressed in E. coli and was collected and purified as an insoluble protein. One milligram of the respective proteins was suspended in 2 mL of Z-Max adjuvant and administered by intramammary injection three times at 7-wk intervals. Luteinizing hormone-releasing hormone antibody binding was elevated in heifers treated with ovalbumin-LHRH-7 compared to ovalbumin-treated heifers (P < .05). Serum progesterone concentrations (< 1 ng/mL) indicate that the estrous cycle of the four heifers treated with ovalbumin-LHRH-7 was suppressed for a time period ranging from 60 to 238 d, which was different from control heifers (P < .01). Serum progesterone for the control heifers continued to exhibit cyclic profiles over the experimental period. This preliminary study in heifers demonstrated that a chimeric LHRH fusion protein induced elevated concentrations of circulating LHRH antibodies that suppressed estrus for an average of 122 +/- 41 d.     

Histopathology and physiopathology of gastric mucous hyperplasia in rats heavily infected with Taenia taeniaeformis.

Rats heavily infected with larval Taenia taeniaeformis show hyperplasia of the gastric mucosa accompanied by mucous cell proliferation, increase in the level of intragastric pH and hypergastrinemia. Sixty one rats were divided into 2 groups designed as infected (36 rats) and control (25 rats) group. These rats were examined with time course of the infection histopathologically and physiopathologically, during 14-112 days postinfection (DPI). In the infected rats, gastric mucosal hyperplasia began to be observed at 56 DPI, and the structural disturbance of zymogenic units in the corpus and mucous units in the antrum had increased with time. However, the degree of these changes in the antrum was weaker than those in the corpus. Alcianblue and/or PAS-positive cells increased in their numbers with time, and 4 types of cells other than typical surface mucous cell and mucous neck cell were observed by electron-microscopy. However, zymogenic and parietal cells decreased in their number after 56 DPI. Further, the infected rats showed changes in the serum concentration of alanine aminotransferase, aspartate aminotransferase, blood urea nitrogen, glucose and total protein. Some similarities with Menetrier's disease were discussed.