III. Buchbesprechungen

Ohne Zusammenfassung     

Pharmacokinetics of recombinant hirudin in healthy horses

REASONS FOR PERFORMING STUDY: Recombinant (r)-hirudin is a specific inhibitor of thrombin that is independent of the activity of antithrombin. OBJECTIVES: To evaluate pharmacokinetic properties and coagulatory changes of r-hirudin in healthy horses. METHODS: Two clinically healthy horses received a single i.v. bolus of 0.4 mg/kg bwt r-hirudin and 6 clinically healthy horses received the same dose subcutaneously (subcut.) q. 12 h for 3 days. Coagulation times and r-hirudin plasma concentration were determined over 720 mins and 3 days after i.v. and subcut. administration, respectively. RESULTS: In all horses, treatment with r-hirudin was not associated with systemic or local side effects. After i.v. injection, the 2 horses showed an elimination half-life of 58 and 80 mins, respectively. After subcut. administration, maximum plasma concentration of r-hirudin occurred at 128 +/- 55 mins and declined with a terminal half-life of 561 +/- 364 mins. Maximum response of activated partial thromboplastin time (aPTT) occurred 1.5 h after administration of r-hirudin. A prolongation of 1.9 +/- 0.2 times the pretreatment value was noted. CONCLUSIONS: Pharmacokinetics of r-hirudin in healthy horses were similar to those in man and other animal species. POTENTIAL RELEVANCE: The results of this study indicate that r-hirudin can be used in horses, but further studies should be performed in order to prove its effectiveness in diseased horses.     

Comparison of lidocaine, xylazine, and xylazine/lidocaine for caudal epidural analgesia in horses.

Caudal epidural analgesia was achieved in 6 adult horses on 3 successive occasions at weekly intervals by injection of lidocaine, xylazine, and a combination of lidocaine/xylazine through indwelling epidural catheters. Analgesia was defined as a lack of response to pinprick and hemostat pressure in the skin of the perineal area. A significant (P < 0.05) difference was not found for time of onset of analgesia between lidocaine (4.3 +/- 0.8 minutes, mean +/- SEM) and the lidocaine/xylazine combination (5.3 +/- 1.3 minutes). Time to onset of analgesia after administration of xylazine was significantly (P < 0.05) longer (32.0 +/- 3.4 minutes) than that for either of the other 2 treatments. Duration of analgesia was significantly (P < 0.05) longer for the combination (329.8 +/- 6.2 minutes) than for either drug used alone (lidocaine, 87.2 +/- 7.5 minutes; xylazine, 204.2 +/- 12.9 minutes). Pulse and respiratory rates were not significantly altered by any of the drugs. Neurologic sequelae were not clinically apparent after administration of the drugs or after chronic epidural catheterization.     

Preinoculation Effects of Light Quantity on Infection Efficiency of Puccinia striiformis and P. triticina on Wheat Seedlings

ABSTRACT In a previous study under controlled conditions, a model was developed to predict the infection efficiency for the wheat leaf and stripe rust fungi based on temperature and dew period during the 24 h after inoculation. The two pathogens differed in their maximum infection efficiency under controlled conditions for temperature and dew period, the infection efficiency was 12 times greater for Puccinia triticina than for P. striiformis. In the present study, the model was validated by field results to predict P. triticina infection efficiency as a function of temperature and dew period only. However, this model failed to predict infection efficiency caused by P. striiformis in the field. The model was adapted to include the effects of light quantity on infection efficiency. Wheat seedlings, grown in climate-controlled rooms and exposed to various regimes of light duration and intensity for 24 h in either field or controlled conditions, were inoculated and incubated in climate-controlled rooms under optimal dew and temperature conditions. Quantity of natural or artificial light (light intensity x duration) received by the plants prior to inoculation enhanced infection efficiency of wheat seedlings inoculated by P. striiformis. Infection efficiency increased from 0.4 to 36% depending on the light quantity according to a Richards' function. For stripe rust, three environmental variables, preinoculation light quantity received by the plants, postinoculation temperature, and postinoculation dew period, were used for fitting a model for infection efficiency measured in the field.