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The variability of the largest wave impacts, where nominally identical waves produce significantly different pressures, is widely known. However, the mechanisms are not well understood. Here we provide a review and investigation of factors affecting the variability of wave impact pressures on steep walls, quantifying the range of parameters that have been used in the literature. We then present two investigations: (i) Setup 1 on the effect of structure slope and (ii) Setup 2 on the effects of kinematics variability on pressure variability. Firstly, wave impacts arising from about 250 focused wave groups interacting with three values of wall steepness (vertical, 10° to the vertical, and 27° to the vertical) showed that steeper walls resulted in larger impact loads, the largest of which were experienced higher up the wall. The maximum pressure data was seen to be a good fit to the Gumbel model for the vertical wall but closer to the log-Normal distribution for the 10° wall. Parameter estimates for those distributions revealed a systematic variation which could potentially be used to predict maximum impact pressures at intermediate wall angles and locations. The pressure wave arising from the impact was seen to be of highly variable speed, for the 10° wall it was estimated to be about 10 m/s at the 1:25 model scale, decreasing for the 27° wall. In the second investigation, which provided kinematics data using particle tracking velocimetry, rapidly varying velocities close to the impact location were observed, with maximum values at impact being a reasonable fit to the Weibull distribution. Findings indicate that though the water surface may appear to be calm, residual sub-surface velocities undoubtedly play some role in the variability of the subsequent wave impact pressures.

All the components of the renin-angiotensin system have been identified in the heart including the angiotensin II receptor subtypes AT1 and AT2 In the normal human heart, there is a decreasing receptor density from the right atrium to the left ventricle. In right atrial membranes prepared from pathological hearts, the percentage of AT1 receptor decreases with the severity of cardiac dysfunction whereas that of AT2 receptor increases. Treatment of hypertrophic rats with AT1 receptor antagonists inhibits cardiac hypertrophy and reverses the increase receptor density, indicating involvement of this Ang II receptor subtype. The role of the AT2 receptor is still largely unknown but it may be involved in cell growth and proliferation. The cloning of both AT1 and AT2 receptors as well as the availability of potent and selective antagonists will help us to understand better the functional role of Angiotensin II in cardiovascular disorders

Continuous addition of Aeromonas salmonicida (which causes furunculosis) or Yersinia ruckeri (which causes enteric redmouth disease, or ERM) broth cultures to recirculating aquaculture systems, without fish, resulted in the presence of these pathogens in the fluidized sand biofilters. Disinfection of the recirculating systems, except biofilters, with 200 ppm sodium hypochlorite and flushing biofilters for 24 hours with spring water did not prevent outbreaks of furunculosis or enteric redmouth disease after stocking Arctic char (Salvelinus alpinus) or rainbow trout (Oncorhynchus mykiss), respectively. Disinfection of the entire recirculating systems with 10 ppm Chloramine-T following outbreaks of furunculosis or ERM, or after addition of broth cultures prevented transmission of enteric redmouth in three trials and in two of three trials with furunculosis. Within 75 days of stocking Atlantic salmon (Salmo salar) with subclinical furunculosis in the recirculating system with rainbow trout, A. salmonicida could be cultured from the mucus of rainbow trout and from the fluidized sand biofilters. Removal of salmon and trout and disinfection of the recirculating system with 10 ppm Chloramine-T prevented a furunculosis outbreak when Arctic char were stocked into the system. However, if the recirculating system was only drained and refilled after removal of salmon and trout, furunculosis occurred within seven days of stocking char.

The E-cadherin-catenin complex is important for the maintenance of epithelial architecture. We studied its expression in Crohn disease, ulcerative colitis, acute ileitis, and controls. Immunohistochemical stainings for E-cadherin, alpha-catenin, beta-catenin and gamma-catenin were performed. E-cadherin messenger RNA (mRNA) was detected using riboprobes. In active inflammation, there was up-regulation of the complex. In particular, epithelium adjacent to ulcers showed increased expression of protein and mRNA, but in ulcer-associated cell lineage, the intensity of staining was weak to negative. In focal inflammation, up-regulation was found in affected areas. Reparative epithelium growing over denuded areas showed weaker expression. Since structural or functional perturbation in any of the molecules of the E-cadherin-catenin complex results in loss of intercellular adhesion, the preexistent epithelium may benefit from up-regulation to try to maintain its normal architecture under inflammatory conditions. Reduced expression in reparative epithelium and ulcer-associated cell lineage could facilitate the motility of these cells., Journal Article, Research Support, Non-U.S. Gov't, info:eu-repo/semantics/published

Four fish chemotherapeutants, formalin, benzalkonium chloride, chloramine-T, and hydrogen peroxide were evaluated for their effect on the nitrification efficiency of fluidized-sand biofilters. The chemotherapeutants were added at conventional concentrations to two small-scale (2,200 L) coldwater recirculating rainbow trout (Oncorhynchus mykiss) culture systems each containing six fluidized-sand biofilters operating in parallel. Nitrification efficiency of biofilters was calculated before and after chemotherapeutant treatments by determining ammonia removal efficiency at ambient conditions, and also when challenged with a sudden increase of ammonium chloride at a concentration four times that of the ambient total ammonia-nitrogen (TAN). Two formalin treatments in recycle bath mode at 167 and 300 ppm were conducted with only the 300 ppm treatment having a significant negative effect on biofilter nitrification efficiency. Four single benzalkonium chloride treatments of one and 2 ppm were conducted; two static bath treatments and two recycle bath treatments. Of these four tests, only the recycle bath treatments caused biofilter nitrification efficiency to be significantly impaired. Two multiple treatments with benzalkonium chloride were conducted: one static bath treatment and one recycle.bath treatment. These treatments caused ammonia removal efficiency to decrease by 18% in the static bath treatment and by 63% in the recycle bath treatment. Of these two tests, only the recycle bath treatment caused a significant impairment of nitrification. Single static bath and recycle bath treatments with 9 ppm of chloramine-T both resulted in significant impairment of nitrification, as did a 12 ppm multiple static bath treatment. A single static bath treatment with 100 ppm of hydrogen peroxide caused almost total failure of nitrification within 24 h of treatment but biofilters were able to remove 23% of TAN within 48 h of treatment.

We conducted a study of the numbers and types of heterotrophic bacteria that occur in a fluidized sand biofilter and in rearing water in a semiclosed trout culture research system at the Freshwater Institute, Shepherdstown, West Virginia. Methods were developed for sampling the biofilter at various depths, removal of bacteria from the biofilm on sand particles, selection of appropriate media for enumeration of bacteria, and plate count procedures. Sonication of sand from biofilters and a spread plate technique provided the best results in determining total counts of heterotrophic bacteria. In addition to determining total heterotrophic bacteria, the study was designed to detect the presence of the opportunistic fish pathogens Aeromonas hydrophila and Pseudomonas fluorescens, as well as denitrifying bacteria.

Aeromonas hydrophila is a common motile bacterium of freshwater streams and ponds that frequently causes internal, generalized infections in fish-particularly cultured species. The infections commonly occur when fish are stressed by crowding, low oxygen, or a buildup of waste products in the water. Cultured warmwater fishes such as channel catfish, baitfishes, and minnows are particularly susceptible. Most A. hydrophila disease outbreaks occur in summer, when water temperatures are about 87-89 deg F (31 deg C). The terms red sore disease and red rot disease have been applied to A. hydrophila infections.

External and internal parasites occur in all species of freshwater and saltwater fishes. In nature, a balance is usually established between parasites and their fish hosts. In intensive fish culture operations, however, parasites can cause significant mortalities. External single-celled protozoan parasites are among the most serious pathogens of cultured freshwater fish. Some of the most common of these are described here.

Enteric redmouth disease (ERM) is a systemic bacterial infection of fishes, but is known principally for its occurrence in rainbow trout, Oncorhynchus mykiss. It was first reported in the 1950's in Idaho rainbow trout and described by Rucker (1966). In recognition of that first description, the causal organism was named Yersinia ruckeri by Ewing et al. (1978)., Revision of Fish Disease Leaflet 57, dtd 1979.

Fish gills function as both respiratory and excretory organs. Basically they consist of a network of capillaries where blood is separated from the surrounding water by only one or two layers of cells. Proliferation of epithelial tissue, and later the loss of surface by the clubbing and fusing of lamellae, impair respiration and the excretion of nitrogenous waste materials, and disturb osmotic balance. Because these changes adversely affect the health of fish, the prevention and treatment of gill diseases are important in fish culture. Pathologic changes in gill tissues have been divided into five categories. Bacterial gill disease, the most lethal of these categories, is discussed here.

Furunculosis is a generalized internal infection prevalent in trout and salmon. The disease was first described in Germany in 1894 and was named for the large raised lesion called a furuncle (Fig. 1) seen in the chronic disease. The bacterium causing the disease is Aeromonas salmonicida. For many years it was believed that A. salmonicida infected only salmon and trout, but variants of the bacterium have now been found to cause goldfish ulcer disease, carp erythrodermatitis, and infections in some marine fishes.

Enteric redmouth disease (ERM) is a systemic bacterial infection of fishes, but is known principally for its occurrence in rainbow trout, Oncorhynchus mykiss. It was first reported in the 1950's in Idaho rainbow trout and described by Rucker (1966). In recognition of that first description, the causal organism was named Yersinia ruckeri by Ewing et al. (1978).

Fish gills function as both respiratory and excretory organs. Basically they consist of a network of capillaries where blood is separated from the surrounding water by only one or two layers of cells. Proliferation of epithelial tissue, and later the loss of surface by the clubbing and fusing of lamellae, impair respiration and the excretion of nitrogenous waste materials, and disturb osmotic balance. Because these changes adversely affect the health of fish, the prevention and treatment of gill diseases are important in fish culture. Pathologic changes in gill tissues have been divided into five categories: (1) bacterial gill disease (BGD) of salmonids and pondfishes, caused by filamentous bacteria that have yellow pigment in their cell walls; (2) nutritional gill disease, caused by a deficiency of pantothenic acid; (3) hemorrhagic gill disease, in which an apparent hemorrhagic condition is really a dilation of lamellar vessels (telangiectasia), caused by toxic agents or physical injury; (4) mycotic gill necrosis in pondfishes, caused by the fungus Branchiomyces (Meyer and Robinson 1973; Niesh and Hughes 1980); and (5) proliferative gill disease of unknown etiology in pondfishes and rainbow trout, Oncorhynchus mykiss (Daoust and Ferguson 1985). Bacterial gill disease, the most lethal of these categories, is discussed here.