Pleistophora infestation in fathead minnows, Pimephales promelas (Rafinesque).

Pleistophora infestation was observed in adult fathead minnows, Pimephales promelas, held under laboratory conditions. Fish were clinically healthy, and presented no gross findings at necropsy. Histopathology revealed parasitic stages only in the ovaries. Spores within sporophorous vesicles were mainly encountered in late vitellogenic oocytes and were ultrastructurally identified as a microsporidian parasite. Heavily parasitized oocytes underwent degeneration followed by the release of spores into the ovarian interstitium. Degenerating oocytes and interstitial spores caused ovarian inflammation. Male fish showed no parasites in the testes. Parasitic infestation was compared with body length, body weight, gonadal weight, gonadosomatic index and plasma vitellogenin levels, and revealed no statistically significant differences between non-parasitized and parasitized females. The isolated holding conditions of the fish and the presence of parasitic stages in the ovaries suggested that an infestation with Pleistophora ovariaeSummerfelt, 1964 was more probable than that with Pleistophora mirandellae (Vaney & Conte, 1901).

Serotonin (5-HT1A-receptor) agonist-induced collecting duct vacuolation and renal papillary necrosis in the rat.

General anxiety in humans is treated with azaspirodecanedions, which act through a reduction of serotonin transmission. Ipsapirone also represents a serotonin (5-HT1A) receptor agonist and was under development as an anxiolytic drug. Histopathologic evaluation of animal experiments revealed cellular swelling and/or vacuolation of renal papillary and medullary collecting duct (MCD) epithelium in rats but not in dogs or mice. The changes ensued already after 1 wk of dosing and were first localized in the inner MCDs. Longer treatment periods showed that these changes proceeded from proximal to distal, approaching the papillary collecting ducts. The changes were most likely the result of altered hemodynamics in the papillary tip. Swelling resulted in partial or total papillary necrosis in some cases. Furthermore, rats treated with ipsapirone showed a sharp and transient rise in urinary endothelin excretion. Concomitantly, urinary PGE2 levels were elevated. In contrast, no elevated levels of endothelin were detected in urine samples of patients from a volunteer study, leading to the conclusion that the human kidney is not susceptible to the ipsapirone-induced alterations seen in the collecting ducts of rats.

Distribution of [14C]-ciprofloxacin in experimentally induced intramuscular abscesses of rats.

Wistar rats were infected by injection of 0.05 ml of a dense oily suspension of Staphylococcus aureus into the posterior thigh muscles of the hind leg. Three days later, solid abscesses had formed which were characterized by a peripheral accumulation of polymorphocytes and incipient central necrosis. At this time, 10 mg/kg of [14C]-ciprofloxacin (1-cyclopropyl-6-fluoro-1,4-dihydro-4-oxo-7-piperazin-1-ylquino line-3-carboxylic acid, Bay o 9867; designated tradename: Ciprobay) were administered intravenously. The animals were sacrificed at various time intervals after treatment and the distribution of radioactivity was examined by whole-body autoradiography. Five min after administration of ciprofloxacin, the radioactivity was found to be differentially distributed among all organs and tissues, but no radioactivity was detectable in the abscess. Beginning from 1 h post appl., increasing relative amounts of radioactivity were seen inside the abscesses. The relative enrichment as compared to the surrounding muscle tissue was most pronounced after 5 h, indicating that the radioactivity was eliminated more rapidly from the muscle than from the abscess. Some radioactivity was still present in the abscess 8 h after treatment of the animals. The comparison of autoradiograms and corresponding histological sections revealed a distinct affinity of [14C]-ciprofloxacin and/or its potential radioactive metabolites to the areas of inflammatory cellular infiltrates.