Acute toxicity of emamectin benzoate (SLICE™) in fish feed to American lobster, Homarus americanus

SLICE? (active ingredient 0.2% emamectin benzoate (EMB)), a feed premix developed by Schering‐Plough Animal Health for the control of sea lice on cultured salmonids, is registered for use in several countries and is being prescribed on an emergency basis in Canada and the United States. The concentration of EMB in feed administered to farmed salmon ranges from 1 to 25 μg g^?1. To determine the acute toxicity of the compound to juvenile and adult American lobster (Homarus americanus), commercial salmon feed was coated with SLICE? at a range of concentrations and provided to the animals for 7 d in the laboratory. The LC₅₀ is estimated to be 644 μg g^?1 (95% CI=428, 1275) for adult lobsters and >589 μg g^?1 for stage V and VI juvenile lobsters. The consumption of medicated pellets by adult lobsters decreased significantly with increasing concentration of EMB. Adult lobsters that died during the study had a significantly greater concentration of emamectin B1a in their muscle tissue than those that survived. These results support the conclusion that salmon feed medicated with EMB at the concentrations used by the aquaculture industry is unlikely to pose an acute lethal threat to adult and small juvenile American lobsters.     

Bioelectrical impedance analysis determination of water content and distribution in the horse

A horse’s hydration status is critical to its health. The accurate and quantitative determination of it has been problematic because of size, length and density of hair, and uneven topography. The objective of this study was to validate a bioelectrical impedance analysis (BIA) method for objectively quantifying hydration status. Monofrequency BIA values and simple biometric measurements were used to construct predictive equations for total body water, plasma, extracellular, and intra-cellular fluid volumes. These predictive equations were correlated with standard body fluid dilution reference methods. The result was an accuracy of ±0.64% for total body water, ±0.17% for plasma volume, ±1.91% for extra-cellular fluid, and ±0.57% for intra-cellular fluid compartments. Less than 5 min was required for all of the measurements and determinations. Therefore, it appears that an accurate measurement of body fluid distribution can be performed on horses using a fast, easy, non-invasive, inexpensive BIA method.     

Blood pressure lowering effect of a pea protein hydrolysate in hypertensive rats and humans

The blood pressure lowering effect of a pea protein hydrolysate (PPH) that contained <3 kDa peptides, isolated by membrane ultrafiltration from the thermolysin digest of pea protein isolate (PPI), was examined using different rat models of hypertension as well as hypertensive human subjects. The PPH showed weak in vitro activities against renin and angiotensin converting enzyme (ACE) with inhibitory activities of 17 and 19%, respectively, at 1 mg/mL test concentration. Oral administration of the PPH to spontaneously hypertensive rats (SHR) at doses of 100 and 200 mg/kg body weight led to a lowering of hourly systolic blood pressure (SBP), with a maximum reduction of 19 mmHg at 4 h. In contrast, orally administered unhydrolyzed PPI had no blood pressure reducing effect in SHR, suggesting that thermolysin hydrolysis may have been responsible for releasing bioactive peptides from the native protein. Oral administration of the PPH to the Han:SPRD-cy rat (a model of chronic kidney disease) over an 8-week period led to 29 and 25 mmHg reductions in SBP and diastolic blood pressure, respectively. The PPH-fed rats had lower plasma levels of angiotensin II, the major vasopressor involved in development of hypertension, but there was no effect on plasma activity or renal mRNA levels of ACE. However, renal expression of renin mRNA levels was reduced by approximately 50% in the PPH-fed rats, suggesting that reduced renin may be responsible for the reduced levels of angiotensin II. In a 3-week randomized double blind placebo-controlled crossover human intervention trial (7 volunteers), significant (p<0.05) reductions (over placebo) in SBP of 5 and 6 mmHg were obtained in the second and third weeks, respectively, for the PPH group. Therefore, thermolysin derived bioactive peptides from PPH reduced blood pressure in hypertensive rats and human subjects, likely via effects on the renal angiotensin system.     

Hindsight in marine protected area selection: A comparison of ecological representation arising from opportunistic and systematic approaches

Systematic approaches to site selection for marine protected areas (MPAs) are often favored over opportunistic approaches as a means to meet conservation objectives efficiently. In this study, we compared analytically the conservation value of these two approaches. We locate this study in Danajon Bank, central Philippines, where many MPAs were established opportunistically based on community preference, with few if any contributions from biophysical data. We began by identifying the biophysical data that would have been available when the first MPA was created in Danajon Bank (1995). We next used these data with the reserve selection software Marxan to identify MPAs that covered the same area as is protected under the current set of MPAs (0.32% of the total study area) and that would protect the greatest number of conservation targets at the lowest cost. We finally compared the conservation value of the current MPAs to the value of those selected by Marxan. Because of the dearth of biophysical data available in 1995 and the small area currently under protection, Marxan identified multiple configurations of MPAs that would protect the same percentage of conservation targets, with little differentiation among sites. Further, we discovered that the costs of obtaining and analyzing these data to be used for conservation planning would have been large relative to resources typically available to conservation planners in developing countries. Finally, we found that the current set of MPAs protected more ecological features than would be expected by chance, although not as many as could be protected using a systematic approach. Our results suggest that an opportunistic approach can be a valuable component of conservation planning, especially when biophysical data are sparse and community acceptance is a critical factor affecting the success of an MPA.     

A review of orbital and intracranial magnetic resonance imaging in 79 canine and 13 feline patients (2004-2010)

Objective To review the distribution of orbital and intracranial disease in canine and feline patients undergoing magnetic resonance imaging (MRI) following referral to a veterinary ophthalmologist and to correlate results of MRI with pathologic conditions including neoplasia, suspected optic neuritis (ON) and orbital cellulitis. Recognized and emerging imaging techniques are reviewed. Procedure Medical records of 79 canine and 13 feline patients were reviewed. Results Neoplasia was diagnosed in 53/92 (57.6%) of patients. The most prevalent types of neoplasia were carcinoma (16/53, 30.1%), sarcoma (11/53, 20.8%), lymphoma (8/53, 15.1%) and presumptive meningioma (9/53, 17.0%). Carcinomas and sarcomas were characterized by bony lysis and intracranial/sinonasal extension. Lymphoma was generally unilateral, less invasive and originated from the ventromedial orbit. Intracranial masses representing presumptive meningiomas frequently exhibited a ‘dural tail’ sign. Diagnosis of suspected ON was made in 13 of 92 (14.1%) patients. Results of MRI in patients with suspected ON included unilateral optic nerve hyperintensity (3/13, 23.0%), bilateral optic nerve hyperintensity (1/13, 7.7%) and optic chiasmal hyperintensity (3/13, 23.0%). Seven suspected ON patients demonstrated intracranial multifocal patchy contrast enhancement (7/13, 53.8%). Diagnosis of orbital cellulitis was made in 12/92 (13.0%) patients. Conclusions Orbital neoplasia was the most common pathologic condition detected. Essential Roentgen characteristics are helpful when diagnosing pathologic processes and providing prognoses in cases of orbital or intracranial disease. Magnetic resonance imaging comprises an important diagnostic component in cases of suspected ON. Emerging contrast and functional MRI techniques as well as SI data may increase our ability to characterize disease processes.     

Kernel Intensity Estimation of 2-Dimensional Spatial Poisson Point Processes From k-Tree Sampling

To estimate the spatial intensity (density) of plants and animals, ecologists often sample populations by prespecifing a spatial array of points, then measuring the distance from each point to the k nearest organisms, a so-called k-tree sampling method. A variety of ad hoc methods are available for estimating intensity from k-tree sampling data, but they assume that two distinct points of the array do not share nearest neighbors. However, nearest neighbors are likely to be shared when the population intensity is low, as it is in our application. The purpose of this paper is twofold: (a) to derive and use for estimation the likelihood function for a k-tree sample under an inhomogeneous Poisson point-process model and (b) to estimate spatial intensity when nearest neighbors are shared. We derive the likelihood function for an inhomogeneous Poisson point-process with intensity λ(x,y) and propose a likelihood-based, kernel-smoothed estimator \(\hat{\lambda}(x,y)\) . Performance of the method for k=1 is tested on four types of simulated populations: two homogeneous populations with low and high intensity, a population simulated from a bivariate normal distribution of intensity, and a “cliff” population in which the region is divided into high- and low-intensity subregions. The method correctly detected spatial variation in intensity across different subregions of the simulated populations. Application to 1-tree samples of carnivorous pitcher plants populations in four New England peat bogs suggests that the method adequately captures empirical patterns of spatial intensity. However, our method suffers from two evident sources of bias. First, like other kernel smoothers, it underestimates peaks and overestimates valleys. Second, it has positive bias analogous to that of the MLE for the rate parameter of exponential random variables.     

Wnt5a control of cell polarity and directional movement by polarized redistribution of adhesion receptors

Mechanisms by which Wnt pathways integrate the organization of receptors, organelles, and cytoskeletal proteins to confer cell polarity and directional cell movement are incompletely understood. We show that acute responses to Wnt5a involve recruitment of actin, myosin IIB, Frizzled 3, and melanoma cell adhesion molecule into an intracellular structure in a melanoma cell line. In the presence of a chemokine gradient, this Wnt-mediated receptor-actin-myosin polarity (W-RAMP) structure accumulates asymmetrically at the cell periphery, where it triggers membrane contractility and nuclear movement in the direction of membrane retraction. The process requires endosome trafficking, is associated with multivesicular bodies, and is regulated by Wnt5a through the small guanosine triphosphatases Rab4 and RhoB. Thus, cell-autonomous mechanisms allow Wnt5a to control cell orientation, polarity, and directional movement in response to positional cues from chemokine gradients.     

Structural insight into the transglycosylation step of bacterial cell-wall biosynthesis

Peptidoglycan glycosyltransferases (GTs) catalyze the polymerization step of cell-wall biosynthesis, are membrane-bound, and are highly conserved across all bacteria. Long considered the "holy grail" of antibiotic research, they represent an essential and easily accessible drug target for antibiotic-resistant bacteria, including methicillin-resistant Staphylococcus aureus. We have determined the 2.8 angstrom structure of a bifunctional cell-wall cross-linking enzyme, including its transpeptidase and GT domains, both unliganded and complexed with the substrate analog moenomycin. The peptidoglycan GTs adopt a fold distinct from those of other GT classes. The structures give insight into critical features of the catalytic mechanism and key interactions required for enzyme inhibition.