Emersion and Terrestrial Locomotion of the Northern Snakehead (Channa argus) on Multiple Substrates.

Most fishes known for terrestrial locomotion are small and/or elongate. Northern snakeheads (Channa argus) are large, air-breathing piscivores anecdotally known for terrestrial behaviors. Our goals were to determine their environmental motivations for emersion, describe their terrestrial kinematics for fish 3.0-70.0 cm and compare kinematics among four substrates. For emersion experiments, C. argus was individually placed into aquatic containers with ramps extending through the surface of the water, and exposed to 15 ecologically-relevant environmental conditions. For kinematic experiments, fish were filmed moving on moist bench liner, grass, artificial turf, and a flat or tilted rubber boat deck. Videos were digitized for analysis in MATLAB and electromyography was used to measure muscular activity. Only the low pH (4.8), high salinity (30 ppt), and high dCO2 (10% seltzer solution) treatments elicited emersion responses. While extreme, these conditions do occur in some of their native Asian swamps. Northern snakeheads >4.5 cm used a unique form of axial-appendage-based terrestrial locomotion involving cyclic oscillations of the axial body, paired with near-simultaneous movements of both pectoral fins. Individuals ≤3.5 cm used tail-flip jumps to travel on land. Northern snakeheads also moved more quickly on complex, three-dimensional substrates (e.g., grass) than on smooth substrates (e.g., bench liner), and when moving downslope. Release of snakeheads onto land by humans or accidentally by predators may be more common than voluntary emersion, but because northern snakeheads can respire air, it may be necessary to factor in the ability to spread overland into the management of this invasive species.

Emersión y locomoción terrestre de la cabeza de serpiente del norte (Channa argus) en múltiples sustratos (Emersion and terrestrial locomotion of the northern snakehead (Channa argus) on multiple substrates) La mayoría de los peces conocidos por locomoción terrestre son pequeños y/o alargados. Las cabezas de serpiente del norte (Channa argus) son grandes pesces piscívoros que respiran aire, anecdóticamente conocidos por sus comportamientos terrestres. Nuestros objetivos fueron determinar sus motivaciones ambientales para la emersión, describir su cinemática terrestre para peces de 3, 0 a 70, 0 cm y comparar la cinemática entre cuatro sustratos. Para los experimentos de emersión, C. argus se colocó individualmente en contenedores acuáticos con rampas que se extienden a través de la superficie del agua y fueron expuesto a quince condiciones ambientales ecológicamente pertinentes. Para los experimentos cinemáticos, los peces se filmaron moviéndose sobre un revestimiento de banco húmedo, césped, césped artificial y una cubierta de bote de goma plana o inclinada. Los videos se digitalizaron para su análisis en MATLAB y se usó electromiografía para medir la actividad muscular. Solo los tratamientos de bajo pH (4, 8), alta salinidad (30 partes por mil) y alto dCO2 (solución de agua de Seltz 10%) provocaron respuestas de emersión. Aunque son extremas, estas condiciones si ocurren en algunos de sus pantanos asiáticos nativos. Las cabezas de serpiente del norte >4, 5 cm usaron una forma única de locomoción terrestre basada en movimientos apéndiculares-axiales que involucra oscilaciones cíclicas del cuerpo axial, junto con movimientos casi simultáneos de ambas aletas pectorales. Los individuos de ≤3, 5 cm usaron saltos de cola para moverse en tierra. Las cabezas de serpiente del norte también se movían más rápidamente en sustratos tridimensionales complejos (ej., césped) que en sustratos lisos (ej., revestimiento de banco), y al moverse cuesta abajo. La liberación de cabezas de serpiente en la tierra por humanos o accidentalmente por depredadores puede ser más común que la emersión voluntaria, pero debido a que las cabezas de serpiente del norte pueden respirar aire, puede ser necesario tener en cuenta la capacidad de propagarse por tierra en el manejo de esta especie invasora. Translated to Spanish by YE Jimenez (yordano_jimenez@brown.edu).

Development and in vitro characterization of vascular endothelial growth factor (VEGF)-loaded poly(DL-lactic-co-glycolic acid)/poly(ethylene glycol) microspheres using a solid encapsulation/single emulsion/solvent extraction technique.

Poly(DL-lactide-co-glycolide) (PLGA)/polyethylene glycol (PEG) microspheres are one modality of controlled delivery of biologically active molecules that would further the development of engineered tissues. As a possible mechanism to stimulate angiogenesis within an engineered tissue, vascular endothelial growth factor (VEGF) and bovine serum albumin (BSA) were coencapsulated into microspheres fabricated from PEG and 50/50 PLGA using a solid-encapsulation/single-emulsion/solvent extraction technique. Two VEGF/BSA ratios were studied: 1:2000 and 1:10,000. Analysis consisted of the loading efficiency, particle size distribution, bright-field microscopy, scanning electron microscopy, release kinetics, and an in vitro human umbilical vein endothelial cell proliferation assay to assess biological activity of the released VEGF. Results show the microspheres could be manufactured, stored, and degraded over 28 days. The burst release rates for 1:2000 and 1:10,000 VEGF/BSA microspheres were 71.87 +/- 8.11 and 27.91 +/- 1.71 ng/mL (mean +/- standard error of the mean), respectively; steady-state release rates were 6.56 +/- 1.10 and 2.21 +/- 0.47 ng/mL, respectively. The microspheres released biologically active VEGF, and the VEGF increased the proliferation of HUVECs in culture (p <.05). The successful development of a novel, cost-effective, scalable technique for producing microspheres loaded with biologically active proteins is presented. Using the data obtained from these studies, a defined concentration of microspheres will deliver a quantifiable level of VEGF at a known release rate.

Hereditary hemochromatosis in liver transplantation.

A candidate gene, HFE, was recently described in patients with hereditary hemochromatosis (HH) and found to contain a missense mutation leading to a cysteine to tyrosine substitution (C282Y). A second mutation, H63D, was also found in the gene. This study was undertaken to determine the HFE genotype in liver transplant recipients clinically diagnosed with HH and those incidentally found to have increased iron deposition in their explanted livers and to evaluate whether biochemical or histological hepatic iron indices (HIIs) correlated with homozygosity for the C282Y mutation. We identified 15 patients clinically diagnosed with various liver disorders other than HH who had increased liver iron deposits among 918 adult patients who underwent liver transplantation from 1988 to 1995. Four additional patients were clinically diagnosed as having HH. Archival explant liver tissue was evaluated for the histological HII according to the method of Deugnier et al, in which an index greater than 0.15 suggests homozygosity for HH. The HII was computed according to established methods, with a value greater than 1.9 suggesting homozygosity for HH. A portion of liver tissue was subjected to DNA genotyping using polymerase chain reaction-amplified products. Two of 4 patients with clinically suspected HH were homozygous for C282Y, and 2 patients had neither mutation. One of the 15 patients not suspected to have HH was a C282Y homozygote, 1 was a C282Y heterozygote, 6 were H63D heterozygotes, and 7 had neither mutation. The histological HII was consistent with HH in 13 patients, whereas the HII was consistent with HH in 6 patients. Thus, in patients with end-stage liver disease, despite fulfilling the established clinical criteria for HH using biochemical and histological parameters, only a minority of patients were homozygous for the C282Y mutation. Hepatic iron overload may result from other causes, and in end-stage liver disease, an elevated HII may not accurately predict HH. Other factors that either control or lead to iron absorption may explain iron overload in these patients.

Temporal effects of cytokines on neonatal cardiac myocyte Ca2+ transients and adenylate cyclase activity.

This study investigates the hypothesis that inflammatory cytokines, interleukin (IL)-1alpha IL-1beta, and tumor necrosis factor (TNF), influence cardiac function by affecting calcium homeostasis and that this effect is mediated by the beta-adrenergic-adenylate cyclase system. After 4 days in culture, neonatal rat ventricular myocytes were treated with cytokines (10 ng/ml) for short (2 h) or longer (18 h) times. Myocyte calcium, contractility, and adenylate cyclase were measured under each condition. Anticipated stepwise increases in adenylate cyclase and intracellular calcium were found in controls (non-cytokine-treated) with 10(-7) M isoproterenol, 10(-7) M isoproterenol + 0.1 mM guanosine triphosphate, and 10(-9) M forskolin. Cells in the presence of cytokine for 2 h show increased basal calcium levels but no changes in adenylate cyclase activities, and isoproterenol fails to elevate adenylate cyclase levels or affect contractile shortening. After long-term treatment with IL-1beta or TNF, but not IL-1alpha, the significantly elevated levels of basal systolic calcium remain, and isoproterenol increases adenylate cyclase activity, unlike after short exposure. Forskolin maximally activates adenylate cyclase following both short- and long-term incubation, but the stepwise increase in activity is blunted following prolonged exposure. Thus short-term cytokine treatment blocks the adrenergic receptor-mediated increases in adenosine 3',5'-cyclic monophosphate, dissociating adenylate cyclase activation from cytokine-mediated increases in cell calcium, whereas longer treatment apparently produces direct affects on adenylate cyclase. Time-dependent differences in contractile response were found with IL-1alpha at 2 h and TNF at 18 h, implying that myofibrillar responsiveness to increased cytoplasmic calcium is dependent on both cytokine species and exposure time.

Back to the beginning. Nursing case management of the older client with alaryngeal speech needs.

A laryngectomy is a devastating event with many responses, the most dramatic of which is the loss of normal voice production. The three most common methods of alaryngeal speech are esophageal speech, artificial larynx, and tracheoesophageal puncture. A nurse case manager who functions as coordinator of formal and informal support systems will help ensure the outcome of satisfactory alaryngeal speech for older laryngectomees.

Androgen receptor in the rat brain--assays and properties.

The existence and relevance of an androgen receptor in the developing brain has been a matter of controversy. We here describe both sucrose density gradient and hydroxylapatite assays which clearly define a distinct androgen receptor in the 24-day-old rat hypothalamus, amygdala and preoptic region, but not in the cortex. This receptor has considerable affinity for estradiol-17beta, thus perhaps accounting for some uncertainty about its nature, but none for diethylstilbestrol or other estrogens, antiestrogens or glucocorticoids. Its Kd for both dihydrotestosterone and testosterone is about 1 X 10(-9) M and for estradiol about 2 X 10(-8) M. Its properties are generally consistent with those of androgen receptor reported for other tissues.