Trends in meat science and technology: the future looks bright, but the journey will be long

With an increasing world population, an increase in affluence and a substantial growth in the demand for high quality protein, the meat sector faces a fantastic but challenging century. New scientific knowledge, technology and creative minds are the main ingredients in order to reach out for this great opportunity. Efficiency all the way from breeding and farming to processing and dispatch is crucial for success. Technology has brought us far, and there is still a huge potential for increased efficiency by implementing best practices on a global scale. New challenges include: hyper flexible automation, more accurate and faster measurement systems and meeting special consumer demands already at the production line. Systems for optimal animal welfare will be even more important and sustainability is no longer a consumer trend but a license to operate. The scientific meat society must provide knowledge and technology so we together can reach out for a seemingly bright future.

DISPLAY-2: a two-dimensional shallow layer model for dense gas dispersion including complex features

A two-dimensional shallow layer model has been developed to predict dense gas dispersion, under realistic conditions, including complex features such as two-phase releases, obstacles and inclined ground. The model attempts to predict the time and space evolution of the cloud formed after a release of a two-phase pollutant into the atmosphere. The air-pollutant mixture is assumed ideal. The cloud evolution is described mathematically through the Cartesian, two-dimensional, shallow layer conservation equations for mixture mass, mixture momentum in two horizontal directions, total pollutant mass fraction (vapor and liquid) and mixture internal energy. Liquid mass fraction is obtained assuming phase equilibrium. Account is taken in the conservation equations for liquid slip and eventual liquid rainout through the ground. Entrainment of ambient air is modeled via an entrainment velocity model, which takes into account the effects of ground friction, ground heat transfer and relative motion between cloud and surrounding atmosphere. The model additionally accounts for thin obstacles effects in three ways. First a stepwise description of the obstacle is generated, following the grid cell faces, taking into account the corresponding area blockage. Then obstacle drag on the passing cloud is modeled by adding flow resistance terms in the momentum equations. Finally the effect of extra vorticity generation and entrainment enhancement behind obstacles is modeled by adding locally into the entrainment formula without obstacles, a characteristic velocity scale defined from the obstacle pressure drop and the local cloud height.The present model predictions have been compared against theoretical results for constant volume and constant flux gravity currents. It was found that deviations of the predicted cloud footprint area change with time from the theoretical were acceptably small, if one models the frictional forces between cloud and ambient air, neglecting the Richardson dependence.The present model has also been validated in widely different experimental conditions such as the Thorney Island instantaneous isothermal releases 8 (unobstructed) and 21 (with semicircular fence), the EEC-55 two-phase propane experiment (with and without linear fence), the Desert Tortoise 4 two-phase ammonia experiment and the Hamburg DAT-638 instantaneous inclined plate experiment and the model predictions were found in reasonable agreement with the experimental data.

Swim bladder gas gland cells produce surfactant: in vivo and in culture

Electron microscopical examination of gas gland cells of the physostome European eel (Anguilla anguilla) and of the physoclist perch (Perca fluviatilis) revealed the presence of significant numbers of lamellar bodies, which are known to be involved in surfactant secretion. In the perch, in which the gas gland is a compact structure and gas gland cells are connected to the swim bladder lumen via small canals, lamellar bodies were also found in flattened cells forming the swim bladder epithelium. Flat epithelial cells are absent in the eel swim bladder, in which the whole epithelium consists of cuboidal gas gland cells. In both species, Western blot analysis using specific antibodies to human surfactant protein A (SP-A) showed a cross-reaction with swim bladder tissue homogenate proteins of approximately 65 kDa and in the eel occasionally of approximately 120 kDa, probably representing SP-A-like proteins in a dimeric and a tetrameric state. An additional band was observed at approximately 45 kDa. Western blots using antibodies to rat SP-D again resulted in a single band at approximately 45 kDa in both species, suggesting that there might be a cross-reaction of the antibody to human SP-A with an SP-D-like protein of the swim bladder tissue. To localize the surfactant protein, eel gas gland cells were cultured on permeable supports. Under these conditions, the gas gland cells regain their characteristic polarity. Electron microscopy confirmed the presence of lamellar bodies in cultured cells, and occasionally, exocytotic events were observed. Immunohistochemical staining using an antibody to human SP-A demonstrated the presence of surfactant protein only in luminal membranes and in adjacent lateral membranes. Only occasionally, evidence was found for the presence of surfactant protein in lamellar bodies.

Analysis of data from spilling experiments performed with liquid hydrogen

This work describes the modelling of liquid hydrogen release experiments using the ADREA-HF 3-D time dependent finite volume code for cloud dispersion, jointly developed by DEMOKRITOS and JRC-Ispra. The experiments were performed by Batelle Ingenieurtechnik for BAM (Bundesanstalt fur Materialforschung und Prufung), Berlin, in the frame of the Euro-Quebec-Hydro-Hydrogen-Pilot-Project and they mainly deal with LH2 near ground releases between buildings. In the present study, the experimental trial #5 was assumed for simulation due to the fact that in this release the largest number of sensor readings were obtained. The simulations illustrated the complex behaviour of LH2 dispersion in presence of buildings, characterized by complicated wind patterns, plume back flow near the source, dense gas behaviour at near range and significant buoyant behaviour at the far range. The simulations showed the strong effect of ground heating in the LH2 dispersion. The model also revealed major features of the dispersion that had to do with the "dense" behaviour of the cold hydrogen and the buoyant behaviour of the "warming-up" gas as well as the interaction of the building and the release wake. Such a behaviour was in qualitative and even quantitative agreement with the experiment. The results are given in terms of concentration time series, scatter plots, contour plots, wind field vector plots and 3-D concentration wireframes. Given all experiment uncertainties, the model gives reasonable results on concentrations levels.

Infection of the glass-eel swimbladder with the nematode Anguillicola crassus

The ability of the nematode Anguillicola crassus to infect eel larvae (glass-eel stage) was tested. The results show that glass-eels fed on infected copepods, the natural intermediate host of the nematode, can be infected. Light microscopical examination of the infected developing swimbladder tissue revealed that the infection results in a significant thickening of the connective tissue. The basolateral labyrinth of gas gland cells is very much reduced in infected swimbladders, and the distance of gas gland cells to blood capillaries is enlarged. Critical swimming speed, defined as the speed where the larvae were no longer able to swim against the current, was similar in infected and uninfected animals. At intermediate speeds (about 60-80% of critical swimming speed) infected eels showed a slightly higher swimming activity than control animals. Resting oxygen consumption, measured as an index of metabolic activity, within the first 2 months of infection was higher in control animals, which may be due to a reduced rate of activity in infected glass-eels. By 4-5 months after the infection, however, it was significantly higher in infected animals. This may indicate that at this stage a higher activity of the animals is required to compensate for the increase in body density, but swimming performance of infected and non-infected glass-eels was not significantly different. Oxygen consumption during swimming activity, measured in a swim tunnel at 50% of maximal swimming speed, also was not affected. The results thus show that even glass-eels can be infected with A. crassus, and this probably contributes to the rapid spread of the nematode in Europe. While aerobic metabolism during swimming activity is not affected at this stage of infection, the swimbladder tissue shows severe histological changes, which most likely will impair swimbladder function.

Histopathological changes in the swimbladder wall of the European eel Anguilla anguilla due to infections with Anguillicola crassus

The histopathological changes in swimbladders of European eels naturally and experimentally infected with Anguillicola crassus were studied using transmission and scanning electron microscopy. During the course of probably several infections swimbladders undergo characteristic changes. In addition to the thickening of the entire swimbladder wall, and to the folded internal surface of this organ, inflammation, migration of white blood cells, fibrosis and changes in the epithelial cells are frequently seen. Epithelial cells tend to proliferate heavily and form hyperplastic tissues; these processes are accompanied by changes in the internal structure of the cells. The normally cubic cells become spherical or columnar and form folds facing the lumen of the swimbladder. As a consequence, most of these cells lose contact with the blood vessels and show no strict polarity. In heavily affected swimbladders the basal labyrinth of the epithelial cells is reduced, i.e. becomes shorter and less densely packed. The lamina propria shows severe fibrosis with infiltration of white blood cells. Larvae of A. crassus, inhabiting the wall of the swimbladder, were found to be surrounded by cell debris, but this local necrosis does not affect the entire swimbladder in its overall structure. These histological findings can partly explain changes in the gas composition in eels infected with A. crassus.

Richness and diversity of parasite communities in European eels Anguilla anguilla of the River Rhine, Germany, with special reference to helminth parasites

A total of 121 European eels (Anguilla anguilla) from 2 sampling sites on the River Rhine were investigated in respect of their parasite communities. Special attention was given to the swim bladders, intestines, gills and fins of the fish. Twelve different parasite species were found to live in and on the eels. Data from each sampling site were kept separate. Parasites found in descending order of prevalence were: Anguillicola crassus, Trypanosoma granulosum, Myxobolus sp., Paratenuisentis ambiguus, Pseudodactylogyrus sp., Bothriocephalus claviceps, Myxidium giardi, Pomphorhynchus laevis, Trichodina sp., Raphidascaris acus, Acanthocephalus lucii and Acanthocephalus anguillae. Significantly different prevalences were reported for L3 larvae of A. crassus, adult P. ambiguus, B. claviceps and Myxobolus sp. at the 2 sampling sites. The highest number of parasite species was recorded from the intestine, which contained up to 6 different helminths. The coexistence of the acanthocephalans P. laevis and P. ambiguus, which showed clear patterns of distribution within the intestine of the respective hosts, was reported for the first time. Up to 3 different helminth species were found in the intestine of individual fish. Among those, acanthocephalans were the most prevalent worms with the eel-specific parasite P. ambiguus as the dominant species not only of the intestinal but also of the total component communities. Both infra and component communities exhibited low diversity and were dominated by this single species. The evenness reached only approximately 50% or less and it remained unclear why the helminth communities of the eels from the River Rhine with its huge catchment area exhibit such a low parasite diversity and high dominance.

Localization of carbonic anhydrase in swimbladder of European eel (Anguilla anguilla) and perch (Perca fluviatilis)

The distribution of carbonic anhydrase in swimbladder tissue and especially in gas gland cells of the European eel (Anguilla anguilla) and the perch (Perca fluviatilis) was analysed using histochemical staining according to Hansson (1967), with modifications proposed by Riddersträle (1991). While in the European eel, gas gland cells are distributed as a single layered epithelium over the whole secretory part of the swimbladder, the gas gland of the perch consists of a compact, richly vascularized 'multilayered' epithelium, in which gas gland cells have contact with the swimbladder lumen via small channels. In spite of these differences in organization, membranes of gas gland cells near blood vessels are richly folded in both species. A strong histochemical staining for carbonic anhydrase was observed in these membrane foldings. With prolonged incubation times a positive reaction was also observed in the cytoplasm of gas gland cells. In addition, the vascular endothelium and the erythrocytes showed a positive histochemical reaction. No staining, however, was visible in apical membranes towards the lumen of the swimbladder. In the perch, swimbladder epithelial cells outside the gas gland showed no positive staining of carbonic anhydrase. The results thus indicate that carbonic anhydrase activity is especially concentrated in membranes facing blood vessels. This suggests that a rapid equilibrium of the CO2/HCO3- reaction in the intracellular as well as in the extracellular space is essential for swimbladder function.

Impact of low water temperature on the development of Anguillicola crassus in the final host Anguilla anguilla

The effect of low water temperatures on the development and viability of larval and adult Anguillicola crassus (Nematoda) in the final host Anguilla anguilla was studied. European eels were experimentally infected with A. crassus and then maintained for 4 mo at 4, 9, 10, and 19 degrees C. Larval development showed a temperature-dependent pattern and was significantly retarded at low temperatures. Third-stage larvae survived a 4 mo period at 4 degrees C without being affected, although they were not able to invade the swimbladder wall at this temperature. In contrast, adult worms were severely harmed during a 4 mo period at 4 degrees C, as reflected by increased mortality and decreased growth and reproductivity as compared to the worms maintained for the same period at 18 degrees C. Starvation for the eels at 4 mo at 19 degrees C did not affect the development and growth of the nematode. The experimentally obtained results support the hypothesis that the spread of A. crassus in boreal regions, e.g. Northern Europe, is restricted by the natural ambient temperature regimes.

Distribution and prevalence of Anguillicola crassus (Nematoda) in eels Anguilla anguilla of the rivers Rhine and Naab, Germany

Over a period of 2 yr eels were collected at several sites along the river Rhine as well as from adjacent waters and examined for Anguillicola crassus in the swimbladder. Additionally eels were collected once from a site on the river Naab (Danube system). All eels were searched for both juvenile and adult stages of A. crassus, revealing prevalences of 80% in eels from the river Rhine and 39% in eels from the river Naab. The mean intensities were 5.6 and 7.7, respectively. With respect to the prevalence and mean intensity of infection, no significant differences were observed between the different sampling sites in the Rhine system. Neither the prevalence nor the intensity showed significant seasonal patterns. Further, no correlation between the condition factor of the eels and intensity of infection with A. crassus could be found. Of all eels examined, 28% showed pathological alterations of the swimbladder.

Changes in gas composition in the swimbladder of the European eel (Anguilla anguilla) infected with Anguillicola crassus (Nematoda)

The effect of Anguillicola crassus (Nematoda) on gas composition in the swimbladder of eels (Anguilla anguilla) was studied using mass spectrometry in feral eels from two German rivers and in experimentally infected eels. In both naturally and experimentally infected eels significant correlations were observed between the proportion of oxygen in the swimbladder and level of infection with Anguillicola crassus. In swimbladders of naturally infected feral eels the contribution of oxygen to swimbladder gas was reduced by 36-62.9% and in experimentally infected eels it was reduced by 11.4-57% compared to uninfected controls. The proportion of CO2 appeared to be lower in infected swimbladders compared to uninfected ones. However, this change was not significant. The findings are discussed in relation to an altered structure of the swimbladder wall due to the parasite.

The effect of the cardioselective beta blocker celiprolol on pulmonary function in asthmatic patients

The influence of single oral doses of 200 mg celiprolol, 100 mg atenolol, and 200 mg metoprolol on airway resistance (Raw) FEV1, VC, and MEF 50 was studied in a randomized double-blind crossover trial. Eighteen patients with hypertension and asthma, 14 men and 4 women, aged 43-75 years, took part. Pulmonary function tests were performed in the morning before treatment and 2 and 5 h after each treatment in the whole-body plethysmograph. The use of bronchodilators was not allowed during the 3 days. There was no significant change in airway resistance, FEV1, and MEF 50 after celiprolol and a slight increase of vital capacity at 2 h. After atenolol there was a decrease of FEV1 and MEF 50 at 5 h. Metoprolol caused an increase in resistance at 2 and 5 h and a fall in FEV1, VC, and MEF 50 at 2 and 5 h. Two patients required bronchodilator therapy after metoprolol and were excluded from evaluation. We conclude that celiprolol appears to be a safe drug in the treatment of asthmatic patients.