Infection dynamics of Cichlidogyrus tilapiae and C. sclerosus (Monogenea, Ancyrocephalinae) in Nile tilapia (Oreochromis niloticus L.) from Uganda.

The infection dynamics of the gill monogeneans Cichlidogyrus tilapiae and C. sclerosus on Oreochromis niloticus with respect to habitat type (reservoir, stream, ponds and cages), host sex, size and seasons was determined between January and November 2008. During the study period, 45.2% of the 650 fish examined were infected with Cichlidogyrus spp. The infected hosts harboured an average of 8.6 ± 3.4 parasites/fish. Across habitat types, the proportion of infected fish was not statistically different. In contrast, the number of parasites recorded on infected fish from different habitat types differed significantly. The highest parasite number was recorded in reservoir-dwelling fish and lowest in stream-dwelling hosts. Concerning sex, more female O. niloticus were infected and harboured a high number of parasites than male and sexually undifferentiated fish. A weak negative relationship was found between rainfall and monthly parasite infections. However, a higher number of parasites and proportion of infected hosts were found during dry than in wet seasons, except in ponds. Results of this study show that differential exposure due to changes in fish behaviour associated with habitat modification and sex may account for the infection difference across the sampled sites. Meanwhile, rainfall and the associated hydrological events are important factors regulating monogenean infections in tropical aquatic environments. The continuous presence of Cichlidogyrus spp. in fish provides evidence of possible parasite outbreaks, indicating the application of biosecurity measures as crucial for the success of intensive fish farming.

Adrenal glands of slaughtered bulls, heifers and cows: a histological study.

The study involved histological and immunohistochemical examinations of the adrenal glands of healthy slaughtered cattle. Glands of 13 bulls, 10 heifers and 10 cows were examined. The following histological findings were observed: Unequal thickness of connective capsule and nodular formations of the zona glomerulosa (ZG), eosinophilic granules in cells of the ZG, globoid arrangement of the zona fasciculata, nodules or pegs of cortical tissue in the medulla, mutual interlacing of superficial and deep zones of the medulla, proliferation of cortical or medullary cells into the blood vessels wall situated in the medulla and focal inflammatory infiltrates. Cortical cells and noradrenalin-secreting (N) cells in the medulla expressed cytoplasmic positivity of S100 protein. Both adrenalin (A) cells and N cells were positive in synaptophysin. The majority of the cells in the cortex and in the medulla displayed were positive for chromogranin A. Electron microscopy showed structureless, electrondense particles of varying size and shape, mostly displaying the having mostly character of secretory granules.

The parasite community of the nase Chondrostoma nasus (L. 1758) from Austrian rivers.

Between April 2003 and November 2006 a total of 191 individuals of the predominantly herbivorous fish species nase Chondrostoma nasus (L. 1758) were examined for parasites from six river sites in Austria. The following parasite taxa were recovered--Ciliata: Trichodina sp., Chilodonella piscicola, Ichthyophthirius multifiliis; Myxozoa: Myxobolus muelleri (cysts) and Myxobolus sp. (cysts); Monogenea: Dactylogyrus vistulae, D. chondrostomi and Dactylogyrus spp., Gyrodactylus sp., Diplozoon paradoxum; Digenea: Diplostomum spathaceum (larv.) and Tylodelphis clavata (larv.); Cestoda: Caryophyllaeus laticeps; Acanthocephala: Pomphorhynchus laevis; Bivalvia: Unio sp. (Glochidia); Crustacea: Lamproglena pulchella; Hirudinea: Piscicola geometra. The only taxa occurring at all sample sites were Dactylogyrus spp., which was also the dominant taxon at most sites, and Myxobolus muelleri, both from the gills of the fish. This is the first record of the parasite community of the nase in Austria.

Parasites of Apollonia melanostoma (Pallas 1814) and Neogobius kessleri (Guenther 1861) (Osteichthyes, Gobiidae) from the Danube River in Austria.

Two invasive fish species, the round goby Apollonia melanostoma syn. Neogobius melanostomus (Pallas 1814) and the bighead goby Neogobius kessleri (Günther, 1861), have established a firm population in Austrian waters during the past 15 years. As there have been no records of the parasite fauna from these populations, a total of 79 specimens of A. melanostoma and 12 specimens of N. kessleri were examined for parasites between May and October 2007 from three different sampling sites from the Danube River in Austria. In total 12 parasite taxa were recovered. The protozoans Trichodina sp. and Ichthyophthirius multifiliis from the gills and skin; two crustacean species, Paraergasilus brevidigitus and Ergasilus sieboldi, from the gills; and the two monogeneans Gyrodactylus sp. and Dactylogyrus sp., from the skin and gills respectively, all occurred at low prevalence and intensities. Furthermore, cystacanths of the acanthocephalan Acanthocephalus lucii were found in the body cavity. Metacercariae of the digeneans Diplostomum sp. and Tylodelphys clavata were found in the lens of the eye and the vitreous humour, respectively. Adults of two digeneans, Nicolla skrjabini and Bunodera nodulosa, were found in the intestine. In addition, during this survey metacercariae of the Holarctic digenean Bucephalus polymorphus, encysted in the skin and fins, with prevalence up to 78%, were recorded for the first time in Austria.

The occurrence of Caryophyllaeus laticeps in the nase Chondrostoma nasus from Austrian rivers: possible anthropogenic factors.

Between April 2003 and November 2006 a total of 198 nase Chondrostoma nasus (L.) were examined for parasites from seven river sites in Austria. The selected sites showed different levels of anthropogenic alterations in river morphology ranging from pristine areas, with minor anthropogenic alterations, to strongly physically altered rivers. A variety of parasites were recovered from the skin, gills, swimbladder and eyes, with Caryophyllaeus laticeps (Pallas) being identified as the only cestode species occurring in the intestine. This is the first record of this species in nase in Austria. Caryophyllaeus laticeps was confined to the first 20% of the intestine, even in heavily infected hosts. The occurrence of C. laticeps within the fish population seems to be correlated with the degree of anthropogenic changes of the nase's habitat. In rivers with a high degree of ecological integrity or in rivers that are only partially dammed, C. laticeps is either absent in C. nasus or occurs with low prevalence (5.6-20%) and low mean intensity values (1.0-4.0). Where anthropogenic factors have changed the entire river into a reservoir, and fish cannot escape, the prevalence of infection with C. laticeps increases from 46.2 to 78.2% and the mean intensity from 8.8 to 17.2.

Helminth communities of the barbel Barbus barbus from large river systems in Austria.

The composition and diversity of the total and intestinal component endohelminth communities were determined in the cyprinid barbel from three study areas in two large river systems in Austria. Two sample sites in the Danube and one site in the River Drau are the only free flowing stretches of these rivers in Austria. Nine helminth species were identified, with the acanthocephalan Pomphorhynchus laevis being dominant in the Danube, with up to 100% prevalence. In the Drau, where the dominant species was the cestode Bathybothrium rectangulum, species diversity was higher than in the Danube.

Dynamics and predicted decline of Anguillicola crassus infection in European eels, Anguilla anguilla, in Neusiedler See, Austria.

The eel population in Neusiedler See has been maintained by regular massive stocking since 1958. After the establishment of the National Park Neusiedler See-Seewinkel in 1993, eel stocking was prohibited and the population, together with the specific parasites of eels, was predicted to decline to extinction within 10 years. This investigation was undertaken to document the decline and extinction of the Anguillicola crassus population in eels. From 1994 to 2001, 720 eels were collected from two sites in the lake. Prevalence and abundance of A. crassus were lower in spring than in summer and autumn and larger eels harboured more parasites than smaller ones. Neither year of study nor sampling site were correlated with parasite infection levels. No significant trend in the population parameters of A. crassus was detected over the 8 years of the survey. This suggested that there had been no significant decline in the eel population. This suggestion was confirmed by investigations of the fishery, which also found evidence of regular illegal stocking. The stability of the A. crassus population over the past decade seems to reflect the lack of change in eel population density. No mass mortalities of eels occurred over the period despite the many similarities between Neusiedler See and Lake Balaton in Hungary. Differences in eel size, eel diet and the lack of large-scale insecticide use are discussed as possible explanations for the absence of eel mass mortalities in Neusiedler See.

Long-term investigation of the composition and richness of intestinal helminth communities in the stocked population of eel, Anguilla anguilla, in Neusiedler See, Austria.

Data from a long-term study of the intestinal helminth parasite community of eels, Anguilla anguilla, stocked into the shallow eutrophic Neusiedler See, Austria, were collected over an 8 year period (1994-2001). In total, 720 eels from 2 sampling sites were examined. The parasite community showed characteristics similar to those in the natural eel populations in rivers of the UK and mainland Europe: it was species poor, with only 5 species (Acanthocephalus lucii, Acanthocephalus anguillae, Raphidascaris acus, Proteocephalus macrocephalus, Bothriocephalus claviceps) comprising the component community and a maximum infracommunity richness of 4 species. Over the period, the intestinal parasite community of the sampling site in Illmitz, which was originally dominated by A. lucii, changed. As levels of A. anguillae increased to a point at which it dominated the community, diversity increased whilst dominance of a single species decreased. By contrast the community in the southern sampling site remained rather constant with a continuous high infection level of A. anguillae and low abundance of A. lucii. Both acanthocephalan species exhibited higher infection levels in larger eels and in different seasons of the year and the infection parameters were significantly different between the years of study. The significant differences in the infection levels of the 2 acanthocephalan species at the 2 sampling sites were surprising as both acanthocephalan species use the same intermediate host, Asellus aquaticus, and the sampling sites were in close proximity and were similar in terms of water quality, host size and invertebrate abundance. Differences in the fish communities of the 2 sampling sites and eel movements rather than interspecific competition are discussed as possible explanations for the differences in the parasite communities of the 2 sampling sites.

Observation of multipactor in an alumina-based dielectric-loaded accelerating structure.

We report a new regime of single-surface multipactor that was observed during high-power testing of an 11.424-GHz alumina-based dielectric-loaded accelerating structure. Previous experimental observations of single-surface multipactor on a dielectric occurred in cases for which the rf electric field was tangential and the rf power flow was normal to the dielectric surface (such as on rf windows) and found that the fraction of power absorbed at saturation is approximately 1%, independent of the incident power. In this new regime, in which strong normal and tangential rf electric fields are present and the power flow is parallel to the surface, the fraction of power absorbed at saturation is an increasing function of the incident power, and more than half of the incident power can be absorbed. A simple model is presented to explain the experimental results.

Fish macroparasites as indicators of heavy metal pollution in river sites in Austria.

This paper describes two approaches to evaluate the use of fish macroparasites as bioindicators of heavy metal pollution at selected river stretches in Austria. Firstly changes in the diversity and richness of endoparasites of the cyprinid barbel, Barbrus barbuls (L.), were tested in relation to heavy metal contents in the aquatic system. Secondly, the bioaccumulation potential of cadmium, lead and zinc was assessed in the acanthocephalan, Pomphorhynchus laevis (Miller, 1776), and compared with that in the muscle, liver and intestine of its barbel host. The present results indicated that in order to validate the role of parasite community patterns related to heavy metal pollution, more investigations on food web dynamics, interelationships between parasites and the presence/absence of intermediate hosts will be essential. Heavy metal concentrations differed significantly between the organs of barbel and P. laevis (P=0.001) with levels up to 2860 fold in the parasite. The high level of heavy metal accumulation in P. laevis compared with that in its barbel host, suggests that despite variability in the parasite infrapopulation, host mobility and feeding behaviour, P. laevis is a most sensitive indicator of heavy metals in aquatic ecosystems.

[Treatment of anterior glenohumeral instability: personal experience with an arthroscopic stabilization technique, its indications and results]. / Resení prední traumatické glenohumerální instability: nase zkusenosti s artroskopickou stabilizacní technikou, její indikace a výsledky.

PURPOSE OF THE STUDY: Arthroscopic treatment of anterior post-traumatic instability of the glenohumeral joint is a recent surgical procedure. The aim of this study was to evaluate the outcomes of the method and define criteria on which indications for this treatment are based. MATERIAL: Fifty-six active, young patients less than 30 years of age were distributed into three groups according to the method of treatment. Twenty patients were treated conservatively (group A), 12 patients had open surgery (B) and 23 patients underwent arthroscopic stabilization of the glenohumeral joint (C). The average follow-up periods in groups A, B and C were 26, 38 and 18 months, respectively. The treatment of all patients in groups B and C was preceded by physical therapy lasting at least 3 months. Contraindications to arthroscopic treatment included Hill-Sachs bony defects, instability involving a fracture of the glenoid cavity, conditions after previous surgery, posterior or multidirectional instability and anterior instability due to a full rupture of the rotator cuff. METHODS: Conservative treatment consisted of early closed reduction, 3 to 4 weeks of immobilization and subsequent physical therapy. Open procedures for Bankart lesions were carried out according to either Cave and Rowe or Bristow, with post-operative immobilization for 4 weeks. Arthroscopic stabilization was performed by the Wolf method. After the size of the defect had been identified, the glenoid rim was scratched to bleed, the detached labrum, including the inferior glenohumeral ligament, was mobilized and, after drilling holes in the glenoid rim, the capsulolabral complex was fixed by means of a Mitek GII anchor with a 1-0 PDS fibre. Three anchors were inserted as a rule. In each group, the number of recurrent dislocations was recorded. In the patients undergoing surgery, the loss of passive external rotation in 90 degrees abduction was assessed and the outcome was evaluated according to the Rowe rating system. RESULTS: Recurrent dislocations were experienced by 13 patients (65%) in group A and two patients (8.7%) in group C; no recurrent dislocation occurred in group B patients. The average loss of external rotation in 90 degrees abduction was 11.3 degrees and 6.7 degrees in groups B and C, respectively. The Rowe scores showed an excellent outcome in 80%, good in 8%, satisfactory in 2% and poor outcomes in 10% of the group B patients; in group C 78% had excellent, 7% had good, 8% had satisfactory, and 7% had poor outcomes. DISCUSSION: The number of recurrent dislocations (8.7%) in our patients treated by arthroscopy was in agreement with the literature data (1 to 40%); both figures refer to recurrent dislocations in subjects involved in body-contact sports. In our patients treated by arthroscopy, the average post-operative loss of external rotation in 90 degrees abduction was lower than in the open surgery group. There were no differences in the Rowe scores between the two surgically treated groups. The patients treated conservatively showed a high number of recurrent dislocations (65%), thus confirming reports by other authors on the failure of this method. CONCLUSIONS: The arthroscopic treatment of anterior post-traumatic glenohumeral instability, using the Wolf method, resulted in a reduction of recurrent dislocations, supposing indication criteria were observed. Its outcomes were comparable with the results of conventional open surgery.

Reactivity of free radicals on hydroxylated quartz surface and its implications for pathogenicity experimental and quantum mechanical study.

We studied the adsorption of hydroxyl radicals and superoxide anion radicals on a hydroxylated alpha-quartz surface using cluster and periodic slab models by means of density functional calculations. Models of two hydroxylated alpha-quartz surfaces--(0001) and (0111)--have been used in the simulations. The hydroxyl radical adsorbs readily on both surfaces. The subsurface Si-O bonds are weakened during the adsorption resulting in surface layer destabilization. This destabilization leads directly to surface disintegration in the case of *OH/(0111) adsorption. The product of the surface disintegration and reconstruction is a surface terminated by silanol groups (Si-OH) and siloxyl radicals (Si-O*). The model calculations suggest that adsorption of *OH on a hydroxylated quartz surface transforms a chemically inert, aged, silanol terminated surface to a very reactive, silicon-based radical terminated surface. The activated surface may then cause oxidative damage to the adsorbed biomaterial. The superoxide anion radical adsorbs on both surfaces, but the adsorption products are only weakly bonded to the surface. The calculated energy barrier for the O2*- activated subsurface Si-O bond dissociation is 10 kcal/mol, which is higher than for the *OH activated process (4 kcal/mol). The calculated weaker bonding to the surface and higher activation energy barrier suggest that the superoxide anion radical will be less efficient in reactivation of an aged, hydroxylated quartz surface than the hydroxyl radical. The importance of the specific geometry of the surface silicon atoms on the surface reactivity and adsorption properties is also discussed. The theoretical predictions are supported experimentally using chemiluminescence to monitor reactivation of the aged silica surface by superoxide anion radicals.

Radio-frequency measurements of coherent transition and cherenkov radiation: implications for high-energy neutrino detection

We report on measurements of (11-18)-cm wavelength radio emission from interactions of 15.2 MeV pulsed electron bunches at the Argonne Wakefield Accelerator. The electrons were observed both in a configuration where they produced primarily transition radiation from an aluminum foil, and in a configuration designed for the electrons to produce Cherenkov radiation in a silica sand target. Our aim was to emulate the large electron excess expected to develop during an electromagnetic cascade initiated by an ultrahigh-energy particle. Such charge asymmetries are predicted to produce strong coherent radio pulses, which are the basis for several experiments to detect high-energy neutrinos from the showers they induce in Antarctic ice and in the lunar regolith. We detected coherent emission which we attribute both to transition and possibly Cherenkov radiation at different levels depending on the experimental conditions. We discuss implications for experiments relying on radio emission for detection of electromagnetic cascades produced by ultrahigh-energy neutrinos.

Endoparasitic helminths of the European eel, Anguilla anguilla, from four disconnected meanders from the rivers Leie and Scheldt in western Flanders, Belgium.

The endoparasitic helminth communities of the European eel, Anguilla anguilla (L.), were investigated in four meanders, cut off from the rivers Leie and Scheldt in western Flanders, Belgium. Six species of helminths (2 cestodes, 2 nematodes and 2 acanthocephalans) were found. The dominant parasite species was the nematode Anguillicola crassus (Kuwahara, Niimi et Itagaki, 1974) infecting 79% of the eel population with intensities up to 112 specimens per fish. At two localities no acanthocephalans could be found, whereas these parasites were very common at the other sites. The prevalence, mean intensity, intensity and abundance, their correlation to the body length, and the frequency distributions were analysed. The site selection of parasites is in relation to food composition and feeding habits of eels, physiological and structural differences in the intestine and possible interspecific competition were discussed.