A seafood risk tool for assessing and mitigating chemical and pathogen hazards in the aquaculture supply chain.

Intricate links between aquatic animals and their environment expose them to chemical and pathogenic hazards, which can disrupt seafood supply. Here we outline a risk schema for assessing potential impacts of chemical and microbial hazards on discrete subsectors of aquaculture-and control measures that may protect supply. As national governments develop strategies to achieve volumetric expansion in seafood production from aquaculture to meet increasing demand, we propose an urgent need for simultaneous focus on controlling those hazards that limit its production, harvesting, processing, trade and safe consumption. Policies aligning national and international water quality control measures for minimizing interaction with, and impact of, hazards on seafood supply will be critical as consumers increasingly rely on the aquaculture sector to supply safe, nutritious and healthy diets.

An experimental means of transmitting pancreas disease in Atlantic salmon Salmo salar L. fry in freshwater.

A challenge model for pancreas disease in Atlantic salmon, Salmo salar L. fry, was developed comparing two salmonid alphavirus (SAV) subtypes: SAV1 and SAV5. Viral doses of 3 × 10(5) TCID50  mL(-1) for SAV1 and 3 × 10(4) for SAV5 were tested in triplicate tanks, each containing 450 salmon fry. Cumulative mortalities of 1.2% were recorded. Titres of virus recovered from the mortalities ranged from 10(2) to 10(7) TCID50  mL(-1) . Fry were sampled at 3, 5 and 7.5 weeks post-challenge. Sampling after 3 weeks revealed a high prevalence of infection in the absence of clinical signs, and infectious virus was recovered from 80% and 43% of sampled fry infected with SAV1 and SAV5, respectively. After 5 weeks pancreas, heart and red skeletal muscle lesions were generally observed, whilst degeneration in white skeletal muscle was observed only in fish infected with SAV1. In situ hybridisation confirmed the presence of viral genome in infected pancreas, heart and muscle. After 7.5 weeks, infectious virus (both isolates) was recovered from 13.3% of the fish sampled, with a viral titre of 10(2) TCID50  mL(-1) . Clearly, salmon fry are susceptible to SAV infection and pancreas disease.

The susceptibility of Atlantic salmon fry to freshwater infectious pancreatic necrosis is largely explained by a major QTL.

Infectious pancreatic necrosis (IPN) is a viral disease with a significant negative impact on the global aquaculture of Atlantic salmon. IPN outbreaks can occur during specific windows of both the freshwater and seawater stages of the salmon life cycle. Previous research has shown that a proportion of the variation seen in resistance to IPN is because of host genetics, and we have shown that major quantitative trait loci (QTL) affect IPN resistance at the seawater stage of production. In the current study, we completed a large freshwater IPN challenge experiment to allow us to undertake a thorough investigation of the genetic basis of resistance to IPN in salmon fry, with a focus on previously identified QTL regions. The heritability of freshwater IPN resistance was estimated to be 0.26 on the observed scale and 0.55 on the underlying scale. Our results suggest that a single QTL on linkage group 21 explains almost all the genetic variation in IPN mortality under our experimental conditions. A striking contrast in mortality is seen between fry classified as homozygous susceptible versus homozygous resistant, with QTL-resistant fish showing virtually complete resistance to IPN mortality. The findings highlight the importance of the major QTL in the genetic regulation of IPN resistance across distinct physiological lifecycle stages, environmental conditions and viral isolates. These results have clear scientific and practical implications for the control of IPN.

Temperature influence on production and longevity of Sphaerothecum destruens zoospores.

The majority of pathogens that cause high host mortalities are capable of infecting more than 1 host species. One characteristic of pathogens, which enables infection of multiple hosts, is the existence of free-living infectious stages, e.g., zoospores that are produced in vast numbers. Understanding the influence of environmental factors, particularly temperature, on the production and survival of these free-living stages is key to predicting future spread and emergence of disease. The rosette agent, Sphaerothecum destruens, is a significant multi-host intracellular fish parasite, with an obligate intracellular spore stage and a free-living (extracellular), potentially infectious, zoospore stage. It has caused high mortalities in endangered and commercially important fish species. Here we investigate the influence of temperature on S. destruens zoospore production and longevity. Our results indicate a wide temperature tolerance of the spore and zooflagellate stage with later onset and longer lifespan of zoospores at lower temperatures. This has important implications for the environmental persistence of S. destruens and provides additional information on the pathogen's life cycle with direct implications for S. destruens risk assessment.

Evidence for an intrarenal renin-angiotensin system in the rainbow trout, Oncorhynchus mykiss.

Physiological and molecular approaches were used to investigate the existence of an intrarenal renin-angiotensin system (RAS) in rainbow trout. Inhibition of angiotensin-converting enzyme by captopril (5 x 10(-4 )M) rapidly decreased vascular resistance of the trunk of the trout, perfused at 19 mmHg, resulting in an increased perfusate flow rate and a decreased intrarenal dorsal aortic pressure. A profound diuresis occurred in the in situ perfused kidney and reflected both increased glomerular filtration rates and decreased water reabsorption (osmolyte reabsorption was unchanged). Renal and vascular parameters recovered once captopril treatment was stopped. Diuretic and vascular effects of captopril on the in situ trout kidney concur with an inhibition of known vasoconstrictor and antidiuretic actions of angiotensin II. However, at a higher perfusion pressure (28 mmHg), captopril had no effect on intrarenal aortic pressure or perfusate and urine flow rates, suggesting that the trout intrarenal RAS is activated by low perfusion pressures/flows. Existence of the renal RAS in trout was further supported by evidence for angiotensinogen gene expression in kidney as well as liver.

Age and binocular advantage: A VEP assessment.

Monocular and binocular visual evoked potentials (VEP's) were recorded in response to contrast-reversing checkerboard patterns of 2 check sizes (14 and 28 min arc) and 2 contrast-reversal rates (1.88 and 7.50 rps) in children (10 and 11-year-olds) and young adults (20 to 30-year-olds). The magnitude of binocular advantage, expressed as the ratio of the binocular to the average monocular response, was assessed by amplitude measurements of the major positive peak. The overall VEP amplitudes were larger for children than for adults across all conditions. The VEP amplitudes for binocularly viewed patterns were also consistently larger than the VEP amplitudes for the monocularly viewed patterns for both age groups. However, when the binocular advantage was expressed as a ratio of binocular to monocular average (MAV), the amplitude difference between the age groups was no longer apparent; although the children's average VEP responses were of a larger amplitude, the binocular advantage remained the same regardless of age.

A new compound curved needle for intradermal suture closure.

A new compound curved needle has been designed and developed for intradermal suture closure from a unique stainless steel alloy, American Society of Testing Materials (ASTM) 45500. This needle has a short, straight, sharpened point with a reverse cutting edge, followed by a curved distal section. Despite its geometry, it exhibited a similar resistance to bending and breakage as did a curved needle with a single radius of curvature manufactured from the same alloy. The design of this new needle enabled the physician to pass it through the dermis with a greater accuracy to a controlled depth and length of bite than curved cutting edge needle with a single radius of curvature.

Emergency medicine magnifying loupes.

A magnifying loupe system has been evaluated for use in emergency medicine. Physicians uniformly preferred a Keplerian lens system over that of the Galilean lens system. The advantages of the Keplerian lens were its increased field of view and its brighter and clearer peripheral image. The Keplerian loupes allowed the physician to visualize the exquisite details of wound configuration and to perform wound closure using microsurgical techniques.

Multiple sclerosis and brain tumor: a diagnostic challenge.

Multiple sclerosis may present as a lesion indistinguishable clinically and radiologically from brain tumor. A case of multiple sclerosis is reported with clinical and radiologic features of a brain tumor. A brain biopsy was later undertaken that provided pathological confirmation of the diagnosis of this demyelinating disease. This case report in conjunction with those in the literature indicate that conservative treatment with steroid therapy and serial computed tomography should establish the diagnosis of multiple sclerosis without the need for surgical intervention.

Evaluation of cohesive and elastic support bandages for joint immobilization.

The purpose of this clinical study was to compare the performance of a new cohesive bandage to that of elastic bandages for joint immobilization. The magnitude of joint immobilization by these bandages was quantitated during isokinetic exercise using a computerized dynamometer. The degree to which the cohesive and elastic bandages reduced range of motion and peak torque of plantar and dorsiflexion was not significantly different. After exercising for 1 hour, the elastic bandage loosens, reducing its ability to immobilize the joint. In contrast, the cohesive bandage maintains its configuration, despite active exercise for 1 hour.

Nonlinearities in binocular visual evoked potentials in children.

Evidence is controversial in respect to the optimal conditions in which visual evoked potentials provide an objective measure of binocular visual function, related and unrelated to stereopsis, and there is little emphasis on the type of stimulus that produces facilitation in binocular recording. We investigated the effects of stimulus type (flicker or pattern), contrast, and temporal modulation on facilitation, which was defined as a binocular response greater than sum of monocular responses. Monocular and binocular responses to sinusoidally modulated flicker and grating patterns were recorded in children and Fourier analyzed. The relationship of the fundamental Fourier component for flicker and the second harmonic component for pattern were each examined as function of temporal modulation at two levels of contrast for monocular and binocular visual evoked potentials. Binocular facilitation was found across all conditions for flicker. Data suggest that processing of pattern and flicker has different sites of origin within the visual system. Facilitation in binocular visual evoked potentials also indicates that they are not a result of simple summation of monocular responses, since there appears a nonlinear component to such interaction.

Congenital giant hairy nevus: implications for treatment.

Congenital giant hairy nevi represent a special group of melanocytic lesions which generally cover large areas of the body surface. Giant hairy nevi assume special significance because of their predisposition to malignant transformation. Adequate treatment of this lesion involves complete surgical excision as early in the child's life as possible.

Computed tomographic angiography.

Computed tomographic angiography performed by the intravenous administration of contrast medium was evaluated in 86 vascular patients. This experience demonstrates a new approach to the evaluation of patients with symptomatic aortic aneurysms, in whom computed tomographic angiography will aid in evaluating the need for emergency surgery. Nonoperative patients are serially evaluated by computed tomographic angiography to detect significant changes in the geometric configuration of their aneurysms. Computed tomographic angiography was beneficial in the evaluation of the patency of vascular reconstructive procedures such as femoropopliteal bypass, aortoiliac bypass and application of a vena caval device. More clinical experience and possibly a rapid sequence technique are needed to evaluate patients with portasystemic shunts.

Effect on tolerance induction of the mode of attachment of the hapten the carrier.

In this study we have investigated the role played by the mode of attachment of the hapten on autologous IgG in the induction of carrier-determined tolerance. Three conjugates of the dinitrophenyl hapten and mouse gamma-globulin were prepared: 1) DNP-epsilon-lysine-MGG, 2) DNP-azo-MGG (which binds to histidine and tyrosine), 3) DNP-must-MGG (which binds to the carboxyl groups of glutamic or aspartic acid). DNP was also bound to the immunogenic carrier keyhole limpet hemocyanin (KLH) by the three different linkages. The three DNP mouse-gamma-globulin conjugates were used to induce tolerance and immediately thereafter the animals were immunized with various DNP-KLH conjugates. Antibody response was tested by a modiciation of the Jerne plaque assay. It was found that DNP-epsilon-lysine-MGG induced tolerance to both DNP-epsilon-lysine-KLH and to DNP-azo-KLH. In contrast, neither DNP-azo-MGG nor DNP-must-MGG induced tolerance to DNP-epsilon-lysine-KLH or to DNP-azo-KLH and DNP-must-KLH, respectively. Clearance studies showed no differences in the catabolic rate of the various hapten mouse gamma-globulin conjugates as compared to unconjugated MGG. However, although DNP-must-MGG and DNP-azo-MGG were not tolerogenic, they were immunogenic. In conclusion, this study demonstrated that not only the nature of the carrier but the mode of hapten binding to his carrier are critical for the induction of hapten specific tolerance.