Echocardiographic evaluation of the bottlenose dolphin (Tursiops truncatus).

Safe and effective echocardiography would represent a valuable tool for marine mammal veterinarians and physiologists evaluating the dolphin heart. Unfortunately, conventional ultrasound technology (transthoracic echocardiography) has been limited by logistic, anatomic, and behavioral challenges. Five mature male Atlantic bottlenose dolphins (Tursiops truncatus) were trained for echocardiographic imaging (four for both transthoracic and transesophageal imaging, and one for only transthoracic imaging). It was noted that transesophageal image quality transiently improved when the dolphins spontaneously exhaled. Subsequently, dolphins were conditioned to hold their breath following forced exhalation, and imaging proceeded during such behavioral breath holds. Over 25 transthoracic and 100 transesophageal echocardiographic studies were performed, including both two-dimensional imaging and color flow mapping. Transthoracic imaging yielded poor-quality images of only small portions of the heart. In contrast, transesophageal imaging, which improved dramatically with behavioral breath holding following exhalation, yielded consistently high-quality images of the entire heart (mitral, tricuspid, aortic, and pulmonary valves, atrial and ventricular septa, left and right atria, left and right ventricles, and ascending aorta and main pulmonary artery). Color flow mapping demonstrated mild tricuspid regurgitation in all dolphins, and mild aortic regurgitation in one dolphin found to have a pedunculated mass arising from the sinutubular junction just above the aortic valve. There were no complications in nonsedated dolphins. The heart of the bottlenose dolphin can be safely, effectively, and reproducibly evaluated with the use of transesophageal echocardiography in conjunction with behavioral breath holding following forced exhalation. This approach, and the normative echocardiographic data generated from this work, lays the foundation for future echocardiographic studies of cetaceans.     

Fibrocartilaginous emboli in a tayra (Eira barbara): a case report.

An 8-yr-old male tayra (Eira barbara) was presented with acute onset of pelvic limb paralysis. Radiography was unremarkable. Neurologic examination showed signs consistent with an intramedullary lesion between the second thoracic and fifth lumbar spinal cord segments. The animal's condition did not improve after 4 days of aggressive glucocorticoid therapy, and euthanasia was performed. Histologic examination of the spinal cord showed amorphous emboli suggestive of cartilaginous fragments within spinal veins. A diagnosis of fibrocartilaginous emboli was made, the first known case in a mustelid.     

Formation of a Reservoir of Sperm in the Oviduct

A reservoir of sperm in the initial segment of the oviduct has been found in several species of domestic and laboratory mammals. Evidently, the reservoir serves to ensure successful fertilization by providing the appropriate number of sperm in the appropriate physiological state for fertilizing oocytes soon after they enter the oviduct. Recent evidence indicates that sperm are trapped in the reservoir by binding to specific carbohydrate moieties on the surface of the mucosal epithelium of the oviduct. A bovine seminal plasma protein has been identified that associates with sperm and confers on them the capacity to bind to the carbohydrate moiety.     

Facilitated sexual behavior reversed and serotonin restored by raphe nuclei transplanted into denervated hypothalamus

Fetal raphe cells transplanted into the hypothalamus reversed facilitation of feminine sexual behavior in rats with brain lesions induced by 5,7-dihydroxytryptamine. Immunocytochemical and chemical analyses of serotonin indicate that reinnervation of the ventromedial nucleus of the hypothalamus by the transplants is associated with behavioral recovery. The findings suggest that transplanted fetal tissue can exert functional regulation over an innate, complex, hormone-dependent behavior in adult rats.     

Plasma cortisol and hypothalamic monoamine responses in yellow perch <Emphasis Type="Italic">Perca flavescens</Emphasis> after intraperitoneal injection of lipopolysaccharide

The concentrations of monoamines in the hypothalamus were determined in yellow perch Perca flavescens before and after injection with lipopolysaccharide (LPS; 3 mg kg⁻¹ fish weight) or saline to test for the presence of neurochemical changes potentially associated with changes in plasma cortisol characteristic of intraperitoneal (ip) challenge with LPS. In the first experiment, yellow perch were injected with saline or LPS and the hypothalamus removed and plasma sampled before and at 0.5, 1.5, 3.0, and 6 h after injection. Plasma cortisol was elevated in both saline- and LPS-injected fish through 1.5 h after injection and returned to levels resembling pre-injection by 3 h after injection. Significantly higher amounts of cortisol in plasma from LPS-injected relative to saline-injected fish were observed 6 h following injection. A significant decrease relative to levels observed 0.5–3 h after handling was observed in serotonin concentrations at 6 h following LPS and saline injection with a concomitant increase in the ratio of 5-hydroxyindoleacetic acid:serotonin. In the second experiment, hypothalamic monoamines were sampled before and at 3, 6, 9, 12, and 24 h after injection with LPS or saline. Significant increases from pre-injection levels were observed in the ratio 5-hydroxyindoleacetic acid:serotonin at 9, 12, and 24 h after injection, but no differences were detected between LPS- and saline-injected fish. These results support a model linking serotonergic system activation following handling stress, but no correlations with the sustained elevations of plasma cortisol associated with inflammatory challenge were observed.     

Comment on "Nonreciprocal light propagation in a silicon photonic circuit"

We show that the structure demonstrated by Feng et al. (Reports, 5 August 2011, p. 729) cannot enable optical isolation because it possesses a symmetric scattering matrix. Moreover, one cannot construct an optical isolator by incorporating this structure into any system as long as the system is linear and time-independent and is described by materials with a scalar dielectric function.