Developmental Exposure to Trace Concentrations of Chlorpyrifos Results in Nonmonotonic Changes in Brain Shape and Behavior in Amphibians

Despite regulations and improved design, pesticides remain ubiquitous in the environment at relatively low, trace concentrations. To understand how prolonged exposure to trace pesticide concentrations impacts vertebrate brain development and behavior, we raised larval amphibians (northern leopard frogs, Lithobates pipiens) in 0, 1, or 10 μg/L of the organophosphorus pesticide chlorpyrifos (CPF) from hatching to metamorphosis. Tadpoles exposed to 1 μg/L CPF, but not 10 μg/L CPF, had changes in relative brain mass, relative telencephalon shape, and behavioral responses to a novel visual cue. Tadpoles exposed to 10 μg/L CPF had altered behavioral responses to predator-associated olfactory cues. After metamorphosis, frogs raised in 1 μg/L CPF, but not 10 μg/L CPF, had changes in the shape of their optic tectum and medulla. Thus, we provide robust evidence that even trace, yet ecologically realistic, concentrations of CPF have neurodevelopmental and behavioral effects that carry over to later life-history stages, further emphasizing the potent effects of trace levels of CPF on vertebrate development. Also, some but not all effects were nonmonotonic, meaning that effects were evident at the lowest but not at the higher concentration of CPF.

External nasal gland morphology of Eurycea bislineata (Amphibia, Urodela, Plethodontidae)

Plethodontid salamanders possess numerous courtship glands. Previous studies have shown that the glands are more prominent in male individuals than females, and often experience periods of atrophy and hypertrophy throughout the year that correlate to the nonmating and mating seasons, respectively. We sampled male and female Eurycea bislineata throughout the year to test the hypothesis that external nasal glands are courtship glands. External nasal glands are paired, branched tubular glands that extend from excretory ducts dorsal to the nares to terminal secretory units posterior to the eyes. We found that the glands hypertrophy and stain/react more intensely with histochemical procedures during the mating season. Hypertrophy of the glands is more pronounced in males, and seasonal variation in epithelial height of external nasal glands of males is significantly correlated to that of seasonal variation in mental gland epithelial height, a known courtship gland found in males, when compared throughout the year. This correlation was not as strong in females, confirming sexual dimorphism of external nasal glands in terms of seasonal variation. We found no ultrastructural differences between male and female external nasal glands. In all specimens, the glandular tubules were lined by a simple, columnar epithelium that was packed with secretory granules that often obscured other cytoplasmic contents.

Water-borne corticosterone assay is a valid method in some but not all life-history stages in Northern Leopard Frogs

There is a particular need to develop conservation tools for use in amphibian populations, which are declining rapidly. Glucocorticoid hormones like corticosterone (CORT) are often used as biomarkers of amphibian stress. A relatively new method of assessing CORT in amphibians is to measure CORT concentrations in water that has held amphibians (water-borne (WB) CORT). Here, we tested whether WB CORT is a valid measure of CORT in larval and metamorphic Northern Leopard Frogs (Lithobates pipiens). We assessed whether levels of WB CORT are different among groups of animals that should have different levels of CORT due to a handling challenge, a pharmacological challenge (ACTH), or developmental stage. We also assessed whether WB CORT was correlated with plasma CORT within individuals. Results indicated that measurement of WB CORT is valid in prometamorphic tadpoles because injection with ACTH increased WB CORT, and WB CORT and plasma CORT levels were correlated within an animal in most cases. However, were unable to fully validate the use of WB CORT in metamorphic frogs (metamorphs) because although injection with ACTH elevated levels of WB CORT, WB CORT was not correlated with plasma CORT within individual metamorphs. Also, there was no correlation between WB CORT and plasma CORT in early stage (premetamorphic) tadpoles or tadpoles undergoing metamorphic climax, indicating that WB CORT is not sensitive enough to detect natural variation of organismal CORT in these groups. Together, results indicated that WB CORT is a valid method of assessing plasma CORT in Northern Leopard Frogs, but only for some life-history stages. Our results illustrate the importance of carefully validating the use of WB CORT for appropriate interpretation of results.

Brain plasticity in response to short-term exposure to corticosterone in larval amphibians

Exposure to stressors and elevation of glucocorticoid hormones such as corticosterone (CORT) has widespread effects on vertebrate brain development. Previous studies have shown that exposure to environmental stressors alters larval amphibian brain morphology and behavior, yet the effects of CORT on amphibian brain morphology are still unknown. We exposed prometamorphic Northern Leopard Frog (Lithobates pipiens (Schreber, 1782)) tadpoles for 7 days to a concentration of exogenous CORT (45.56 μg/L) that produced physiologically relevant increases in plasma CORT. This brief exposure to CORT, relatively late in development, resulted in a significantly larger diencephalon width (relative to body mass) when compared with controls. Although we were unable to detect changes in behavior or body morphology, our results indicate that brain shape is modulated by exposure to CORT. More studies are needed to better understand what accounts for the CORT-induced change in brain shape as well as the functional consequences of these changes.

Insecticide-induced changes in amphibian brains: How sublethal concentrations of chlorpyrifos directly affect neurodevelopment

Widespread use of pesticides often contaminates natural habitats, exposing nontarget organisms to pesticides that were designed to control pest populations. Even low levels of pesticides can affect aquatic communities both directly and indirectly. Previous work has shown that trace amounts of the pesticide chlorpyrifos altered tadpole morphology and neurodevelopment in artificial ponds (mesocosms). To determine whether effects resulted from direct chlorpyrifos exposure or from disruption of the food web due to a pesticide-induced decline in zooplankton, we examined the impacts of chlorpyrifos on amphibian development in the presence of chlorpyrifos-resistant zooplankton, a key component of the aquatic trophic community. Northern leopard frog (Lithobates pipiens) tadpoles were reared through metamorphosis in mesocosms containing either 0 or 1 µg/L chlorpyrifos and either chlorpyrifos-resistant or chlorpyrifos-sensitive Daphnia pulex zooplankton. Developmental exposure to chlorpyrifos resulted in metamorphs with a relatively wider optic tectum, medulla, and diencephalon compared with controls, and this result was found regardless of the zooplankton population within the mesocosm. Thus, chlorpyrifos directly impacted brain development, independent of the effects on the trophic community. With respect to body shape, chlorpyrifos had no effect on body shape of metamorphs reared in mesocosms with chlorpyrifos-sensitive zooplankton, but body shape was sensitive to zooplankton population in the absence of chlorpyrifos. To conclude, low, ecologically relevant doses of organophosphorous pesticides can directly impact neurodevelopment in a vertebrate model. Environ Toxicol Chem 2018;37:2692-2698. © 2018 SETAC.

The removal of well-fixed porous ingrown femoral components

It is now evident that some biologically well-fixed hip prostheses may require removal and/or revision much earlier than originally anticipated. The relatively atraumatic removal of porous ingrown but clinically unacceptable femoral components, while difficult, has become increasingly feasible because of accumulated clinical experience and advances in biomedical technology. Preoperative planning, adequate instrument armamentarium, and intraoperative patience are important keys to the successful removal of these implants.

Ipsilateral carpal, metacarpal, and ankle fractures resulting from an attempted basketball slam-dunk. A case report

A 23-year-old male recreational basketball player sustained an open ankle fracture and ipsilateral carpal and metacarpal fractures as a result of a fall while attempting a slam-dunk. The wrist and hand fractures were treated nonoperatively. The open ankle fracture required irrigation, debridement, and open reduction/internal fixation. In addition to the prerequisite leaping ability, long-term success in "playing above the rim" requires experience, exceptional physical agility, and the mental discipline to anticipate and avoid slam-dunk opportunities with high risk for personal injury.

Obturator hip dislocation with ipsilateral fractures of the femoral head and femoral neck. A case report

A 28-year-old female pedestrians, struck by an automobile, sustained an obturator hip dislocation with concomitant ipsilateral fractures of both the femoral head and femoral neck. This unusual hip injury seems not to have been previously reported. The femoral neck fracture was widely separated from the shaft, and unfortunately, a 6-mm deep indentation fracture involved the anterosuperior portion of the articulating surface of the femoral head. This complex injury was treated with a press-fit bipolar prosthesis.

Traumatic spondylolisthesis of the axis in a patient presenting with torticollis. A case report

In a 34-year-old man with an acute traumatic spondylolisthesis (ATS) of the axis, the presenting physical sign was severe torticollis associated with reactive spasm of the right sternomastoid muscle. Computed axial tomography (CAT) was useful both in assessing the nature of ATS (which involved more displacement of the axis fracture and adjacent soft-tissues on the right side of the neck) and in ascertaining reduction, realignment, and healing. The reduction was sustained by halo-vest immobilization.

Revision of failed hip surface replacement arthroplasties with a bipolar prosthesis. Three case reports with two- to three-year follow-up observations

Three cases of an isolated femoral component failure of a hip surface replacement were treated by use of a press-fit bipolar prosthesis to articulate with the retained acetabular cup. At two to three years post-surgery (average, 31 months), these three conversions had good clinical function and maintained an acceptable radiographic appearance. While no optimal long-term solution currently exists for failed hip surface replacements in young adults, this rather straightforward surgical conversion may have a role to play in the interim management of some of these patients.

Atraumatic removal of a well-fixed porous ingrowth hip prosthesis

The authors describe their experience in the removal of a firmly fixed porous coated femoral component of a bipolar hip prosthesis in a 36-year-old man on a methadone maintenance program. The uncemented prosthesis had been implanted for 15 months when the patient complained of hip pain. A methicillin-resistant Staphylococcus aureus infection was found in the hip joint. It was decided to remove the femoral component when the infection failed to respond to irrigation, debridement, and several weeks of intravenous antibiotic therapy and because the patient developed early signs of impending renal compromise and a deterioration of his general nutritional status. The technique for separating and removing the well-fixed porous ingrowth component from its intramedullary environment without damaging the cortical tube of the proximal femur is described.

Myositis ossificans following porous-ingrowth TK replacement

Clinically significant myositis ossificans of the distal thigh following virginal porous-ingrowth total knee arthroplasty has not been previously reported. Associated and potentially contributing factors in this particular case were (1) the patient's preoperative hypertrophic gonarthrosis, (2) our difficulty in regulating her postoperative sodium warfarin (Coumadin) dosages, (3) the postoperative knee manipulation, and (4) possibly, the additional surgical exposure of this patient's distal femur required to use the femur-based alignment instrumentation. Postoperative heterotopic ossification developing in the vicinity of a porous-ingrowth total knee prosthesis can have clinical significance. Treatment of this problem by a means that does not interfere with early bone ingrowth into the implant is a practical concern that warrants investigation.