Percutaneous malathion absorption by anuran skin in flow-through diffusion cells.

There is increased concern about the sublethal effects of organophosphorous (OP) compounds on human and animal health, including the potential role of OP compounds in the global decline of amphibian populations. Malathion is one of the most widely used OP pesticides with numerous agricultural and therapeutic applications, and exposure to environmentally applied malathion can lead to adverse systemic effects in anurans. Cutaneous absorption is considered a potentially important route of environmental exposure to OP compounds for amphibians, especially in aquatic environments. One in vitro system commonly used to determine the absorption kinetics of xenobiotics across the skin is the two-compartment Teflon flow-through diffusion cell system. To establish cutaneous absorption kinetics of malathion, six full thickness skin samples taken from both the dorsal and ventral surfaces of each of three bullfrogs (Rana catesbeiana) and three marine toads (Bufo marinus) were placed into two-compartment Teflon flow-through diffusion cells perfused with modified amphibian Ringer's solution. A 26µg/cm(2) dose of malathion-2,3-(14)C diluted in 100% ethanol was applied to each sample (0.44-0.45µCi). Perfusate was collected at intervals over a 6h period and analyzed for (14)C in a scintillation counter. At the end of 6h, surface swabs, tape strips, biopsy punches of the dosed area of skin, and peripheral samples were oxidized and analyzed for residue effects. Malathion absorption was greater across the ventral skin compared to dorsal skin in both bullfrogs and marine toads.

Percutaneous malathion absorption in the harvested perfused anuran pelvic limb.

The objective of this study was to establish an accurate in vitro model for cutaneous absorption in anurans. The harvested perfused anuran pelvic limb (HPAPL) model maintains the anatomic and physiologic integrity of the skin from the pelvic limb, including the intact capillary network. Radiolabeled malathion was applied to the skin of the dorsal thigh, and perfusate was collected over a 6h period. Residues from the skin surface, stratum externum, and dosed area beneath the stratum externum were analyzed. Kinetic parameters were calculated from these data. Absorption was significantly less for the HPAPL than previously reported for Teflon flow-through diffusion cells. However, partitioning effects were comparable. The HPAPL is an appropriate in vitro model for examining cutaneous absorption kinetics in the bullfrog.

Measurements of common iliac arterial blood flow in anurans using Doppler ultrasound.

Color Doppler ultrasonography was used to determine time-average mean velocity and cross-sectional area of the common iliac artery in bullfrogs (Rana catesbeiana) and marine toads (Bufo marinus). Volumetric blood flow and weight-adjusted blood flow measurements were calculated from this data. Volumetric flow rates of frogs (31.8 ml/min) and toads (23.6 ml/min) did not differ statistically. However, when flow rates were adjusted for body mass, toads displayed a significantly greater flow rate of 238.1 ml/min/kg compared to 114.4 ml/min/kg for frogs.

Viability of glycerol-preserved and cryopreserved anuran skin.

Anurans are important animal models for studying the effects of anthropogenic chemical contamination of the environment. Two-compartment Teflon flow-through diffusion cells can be used to study percutaneous absorption of xenobiotics across harvested skin. However, such an approach currently necessitates that skin be harvested just before experimentation, a requirement that calls for the continuous growth and housing of living animals. The ability to preserve and store skin would allow more efficient use of animals and more flexibility in experimental design. To this end, we examined the viability of harvested anuran skin stored under various protocols consistent with current practices of mammalian skin preservation. Skin from the American bullfrog maintained 80-85% viability after 28 d, whereas viability of skin from the marine toad was only maintained for 7-10 d.

Fibrosarcoma of the brood pouch in an aquarium-reared lined seahorse (Hippocampus erectus).

An adult, male, captive lined seahorse (Hippocampus erectus) was presented with weight loss, anorexia, and brood pouch distention. Initial treatments included manual expression of the brood pouch followed by saline flushes and enrofloxacin infusions. Radiographs and physical examination identified a nodular swelling in the brood pouch wall. The mass was excised, but the seahorse died. Necropsy and histopathology revealed a malignant mesenchymal tumor with a collagenous stroma, and a brood pouch fibrosarcoma was diagnosed.

Novel technique for retroperitoneal implantation of telemetry transmitters for physiologic monitoring in Göttingen minipigs (Sus scrofa domesticus).

Telemetric monitoring of physiologic parameters in animal models is a critical component of chemical and biologic agent studies. The long-term collection of neurobehavioral and other physiologic data can require larger telemetry devices. Furthermore, such devices must be implanted in a location that is safe, well-tolerated, and functional. Göttingen minipigs (Sus scrofa domesticus) present an ideal large animal model for chemical agent studies due to their relatively small size, characterized health status, and ease of training and handling. We report an effective approach to implanting a novel device to measure transthoracic impedance to approximate respiratory tidal volume and rate in Suidae. We tested the approach using 24 male Göttingen minipigs. A ventral midline abdominal incision extending from the umbilicus to the prepuce was followed by a paramedian incision of the parietal peritoneum and dorsal blunt dissection to create a retroperitoneal pocket. The device was anchored inside the pocket to the internal abdominal musculature with 3-0 nonabsorbable suture, biopotential leads were routed through the abdominal musculature, and the pocket was closed with 3-0 absorbable suture. Paired biopotential leads were anchored intermuscularly at the level of the seventh rib midway between spine and sternum bilaterally to provide surrogate data for respiratory function. Postoperative recovery and gross pathology findings at necropsy were used to assess safety and refine the surgical procedure. Results demonstrated that this procedure permitted effective monitoring of complex physiologic data, including transthoracic impedance, without negatively affecting the health and behavior of the animals.