Atypical thymoma in a horse: Diagnostic approach and application of an alternative histological classification system

Thymoma is a rare condition in horses. This case of a 24-year-old Warmblood gelding that was presented with oedema and signs of vascular congestion of the left forelimb caused by a thoracic mass is described. The diagnostic work-up included blood chemistry, cytology of pleural effusion, ultrasonography, radiography and the visualisation and collection of a tissue sample by thoracoscopy. Finally, post-mortem findings and histopathology revealed thymic epithelial neoplasia with histomorphologic features previously unreported in horses. The unique mixture of spindle-shaped and epithelioid tumour cells in combination with clear features of malignancy suggested the application of the Moran and Suster histological classification system for thymomas in humans (Moran and Suster, 2008, Curr. Treat. Options Oncol., 9, 288), which has not been reported in an equine case before and fits well to the present case.     

Purification and characterization of hepatic triacylglycerol lipase isolated from rainbow trout,Oncorhynchus mykiss

Trialcylglycerol (TG) lipase was isolated and partially purified from rainbow trout liver. Triacylglycerol lipase activity was assayed by measuring¹⁴C-oleic acid release from¹⁴C-triolein.¹⁴C-oleic acid release was linear for up to two hours. Optimal activity occurred at pH 7.0 and 15°C. Most of the lipase activity was recovered in the cytosolic fraction. A 27,000-fold purification was achieved after Sepharose (Bio-gel A 0.5 M, 200–400 mesh) chromatography of a resuspended 20% ammonium sulfate fraction. The molecular weight of the trout hepatic lipase as determined by size-exclusion chromatography and by SDS-polyacrylamide gel electrophoresis was 40–43 kD. Lipase-mediated hydrolysis of TG resulted in the production of diacylglycerols, monoacylglycerols, and fatty acids. Kinetic analysis indicated that V_max=0.016 nmol/h/mg protein and that K_m=0.28 mM triolein. Lipolytic activity was enhanced in the presence of cAMP/ATP-Mg²⁺. These results suggest that the liver of trout possesses a neutral TG lipase that is responsible for mobilizing stored TG and is catalytically activated by phosphorylation.A part of this work was presented at the Annual Meeting of the American Society of Zoologists, December 26–30, 1990, San Antonio, TX.     

Maximal lactate concentrations in horses after exercise of different duration and intensity

Lactate kinetics in whole blood of horses was investigated after exercise of differing velocities and duration. The following categories of exercise were used: A: <11 m/second and >180 seconds (n=35), B: >11 m/second and <180 seconds (n=17) and C: <11 m/second and <180 s (n=10). The mean peak lactate concentration determined in horses in category A was 4.49 ± 2.21 mmol/1, in B, 16.32 ± 4.81 mmoVl and in C, 4.58 ± 1.59 mmol/l. While the maximum lactate concentrations in categories A and C were always found immediately after the exercise, the peaks in category B were measured between the first and tenth minute after exercise. Mean lactate concentrations measured at 2-minute intervals after bouts of category-B exercise tended to stabilize 3 to 10 minutes after exercise; however, mean lactate concentrations measured during the intervals before and after the peak value differed significantly. The lactate concentration returned to pre-exercise levels within 20 minutes after exercise bouts of category C, but remained above pre-exercise levels up to 60 minutes after bouts of category-A and -B exercise. It was concluded that, for an evaluation of lactate data after intensive anaerobic exercise, sequential blood sampling at 2-minute intervals for a period of up to 12 minutes after exercise is necessary. Less frequent sampling may be a reason for the often described irreproducibility of lactate concentrations in horses. After aerobic or mild anaerobic exercise, one sample is sufficient, but it has to be taken as soon as possible after exercise.     

Waldschutz gegen Borkenkäfer: Der Beitrag von Duftstoffmeteorologie und Populationsdynamik

Zusammenfassung Mit theoretischen Modellen kann die Effektivität verschiedener Ansätze (z. B. Fallenzahl und-abstand, Ködermenge und-abgaberate) für den Einsatz von synthetischen Pheromonen in Pest-Management-Systemen verglichen werden. Das GAUSS-sche Modell, das von einer Normalverteilung der Konzentrationsabnahme um eine Lockstoffquelle ausgeht, wurde benutzt, um fürT. lineatum die lockwirksame Reichweite und die Konkurrenzsituation von Naturköder und Falle abzuschätzen. Bei 100 000 /ha und 2 Wochen Flugdauer ergeben sich für (+)-Lineatin (Reaktionsschwelle 0,1 ng/m³, Produktion 6,43 ng//d, Produktionsdauer 3 d/) mittlere Tagesraten von 128,6 g/ha bzw. eine Gesamtproduktion von 1,929 mg/ha. Die lockwirksame Reichweite x_max beträgt je nach Wetterlag für 1T. lineatum- 20–40 cm, für Fallen mit 1 CONREL-Faser (Abgaberate 10 g/d [+]-Lineatin) 13–16m. Für eine 10fach höhere lockwirksame Reichweite sind nach dem Modell etwa 100fach, in der Praxis nach verschiedenen Autoren sogar 200fach stärkere Köder erforderlich.In Freilandversuchen über die Relation von Fangleistung und Beifängen unterschiedlicher Fangsysteme waren die Coleoptera (bes. Rhizophagidae und Staphylinidae) am häufigsten. In Trichterfallen lagen die Beifänge mit 9,2% deutlich höher als in Schlitzfallen (1,2%). Das Giftpolter hatte demgegenüber das größte Beifangspektrum; hier traten auch Ordnungen auf, die von anderen Fangsystemen nicht betroffen waren.Massenfang kan prinzipiell in Holzhöfen und Waldbeständen erfolgreich durchgeführt werden. Allerdings ist das Problem der Beifänge noch ungelöst und die Relations von potentieller Vermehrung der Borkenkäfer und maximal möglicher Populationsreduzierung durch Fallenfang unbekannt. Zudem kann eine nach Massenfang geringere Populationsdichte im Folgciahr durch zunehmende Reproduktionsraten oder durch ersatzweise Einnischung (competive displacement) anderer Borkenkäferarten ausgeglichen und damit der Forstschutzeffekt zunichte gemacht werden.

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Bark beetle control: contribution of pheromone meteorology and population dynamics

The use of semiochemicals in pest management systems of bark beetles is viewed in relation to optimization of resources investment, comparing beetle numbers in univoltine, requisitegoverned woodboringTrypodendron lineatum (Oliv.) with multigeneration bark inhabitingIps typographus (L.). The efficiency of different numbers of and distance between traps and pheromone load of dispensers was analysed using steady state models and comparing results with published and own field data. Competition between traps and beetle-infested logs, attractive distance and overlap of pheromone plume was compared forT. lineatum using models which assume a GAUSS distribution of concentration decrease around a pheromone source. For (+)-lineatin (reaction threshold 0.1 ng/m³, production 6.43 ng//d, duration of production 3 d/), 100,000 /ha and a flight period of 2 weeks, daily mean production is 128.6 g/ha. Attractive distance x_max is 20–40 cm for 1T. lineatum- and 13–16 m for a trap with 1 CONREL-dispenser (mean release rate 10 g/d (+)-lineatin). A 10-fold increase of attractive distance x_max needs a 100-fold increase of pheromone release rate according to the model, and 200-fold according to field experiments.In field experiments, Coleoptera (esp. Staphylinidae and Rhizophagidae) were the most abundant non-target trap catches. Insecticide-treated trap logs had the widest range of non-target insects including orders that were not affected by the non-insecticide trapping systems. Mass trapping can be successful in logging areas and/or forests. However, the exclusion of non-target insects still is an unsolved problem and we still have only limited knowledge on potential population increase of beetles and maximum reduction that can be achieved by trapping. Also, population levels reduced by mass trapping can be compensated by increasing reproductive effort of the succeeding generation and/or competitive displacement by secondary bark beetle species.

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Mit 5 Abbildungen und 2 Tabellen

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Mit Unterstützung der Deutschen Forschungsgemeinschaft.

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Nach einem Vortag bei der Fortbildungstagung des Hessischen Forstvereins in Solms/Lahn am 23. Mai 1991.

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Herrn Prof. Dr. Dr.G. Wellenstein zum 85. Geburtstag.