Oxidative damages and antioxidant defences after feeding a single meal in rainbow trout.

Feeding and digestion are metabolically demanding causing a rise on metabolic rate called Specific Dynamic Action (SDA). Although SDA has been vastly reported in fish, its potential consequences on the oxidative-antioxidant balance has not been evaluated to date in fish, a model with a long alkaline tide associated with feeding as well. Using rainbow trout (Oncorhynchus mykiss) as a model species, the aims of the present study were to: (1) assess potential oxidative damages and changes in oxidative defences after feeding on a single meal, and (2) identify the timescale of such changes over a 96 h post-feeding period. Oxidative damage in proteins and lipids and the activities of four enzymatic antioxidant defences: superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase (GPx) and glutathione-S-transferase (GST) were measured in gill, stomach, intestine and liver. DNA damage was measured in red blood cells. Fish were sampled before and after 1.5, 6, 24, 48, 72 and 96 h of ingestion of a 3% body mass ration. Trends of post-prandial damage were present in all tissues, but only protein oxidation varied significatively during digestion in the stomach. The intestine and stomach presented the highest enzymatic activities, likely due to the high metabolic action that these tissues have during digestion, with peaks during post-feeding: at 24 h of SOD in stomach and at 48 h of CAT in intestine. Observed GPx peaks during post-feeding in gills are likely due to the exacerbated demands for ion fluxes and/or oxygen during feeding. The differential response of the antioxidant system observed in tissues of rainbow trout during digestion indicates a coordinated and tissue-specific antioxidant defence.

Measles outbreak in Greater Manchester, England, October 2012 to September 2013: epidemiology and control.

This paper describes the epidemiology and management of a prolonged outbreak of measles across the 2.7 million conurbation of Greater Manchester in the United Kingdom. Over a period of one year (from October 2012 to September 2013), over a thousand suspected measles cases (n = 1,073) were notified across Greater Manchester; of these, 395 (37%) were laboratory-confirmed, 91 (8%) were classed as probable, 312 (29%) were classed as possible and 275 (26%) excluded. Most confirmed and probable cases occurred in children within two age groups­infants (too young to be eligible for measles-mumps-rubella (MMR) vaccination according to the national immunisation programme) and children aged 10-19 years (low vaccine uptake in this cohort because of unfounded alleged links between the MMR vaccine and autism). During this one year period, there were a series of local outbreaks and many of these occurred within the secondary school setting. A series of public health measures were taken to control this prolonged outbreak: setting up incident management teams to control local outbreaks, a concerted immunisation catch-up campaign (initially local then national) to reduce the pool of children partially or totally unprotected against measles, and the exclusion of close contacts from nurseries and school settings for a period of 10 days following the last exposure to a case of measles.

Osmoregulatory bicarbonate secretion exploits H(+)-sensitive haemoglobins to autoregulate intestinal O2 delivery in euryhaline teleosts.

Marine teleost fish secrete bicarbonate (HCO3 (-)) into the intestine to aid osmoregulation and limit Ca(2+) uptake by carbonate precipitation. Intestinal HCO3 (-) secretion is associated with an equimolar transport of protons (H(+)) into the blood, both being proportional to environmental salinity. We hypothesized that the H(+)-sensitive haemoglobin (Hb) system of seawater teleosts could be exploited via the Bohr and/or Root effects (reduced Hb-O2 affinity and/or capacity with decreasing pH) to improve O2 delivery to intestinal cells during high metabolic demand associated with osmoregulation. To test this, we characterized H(+) equilibria and gas exchange properties of European flounder (Platichthys flesus) haemoglobin and constructed a model incorporating these values, intestinal blood flow rates and arterial-venous acidification at three different environmental salinities (33, 60 and 90). The model suggested red blood cell pH (pHi) during passage through intestinal capillaries could be reduced by 0.14-0.33 units (depending on external salinity) which is sufficient to activate the Bohr effect (Bohr coefficient of -0.63), and perhaps even the Root effect, and enhance tissue O2 delivery by up to 42 % without changing blood flow. In vivo measurements of intestinal venous blood pH were not possible in flounder but were in seawater-acclimated rainbow trout which confirmed a blood acidification of no less than 0.2 units (equivalent to -0.12 for pHi). When using trout-specific values for the model variables, predicted values were consistent with measured in vivo values, further supporting the model. Thus this system is an elegant example of autoregulation: as the need for costly osmoregulatory processes (including HCO3 (-) secretion) increases at higher environmental salinity, so does the enhancement of O2 delivery to the intestine via a localized acidosis and the Bohr (and possibly Root) effect.

Contribution of fish to the marine inorganic carbon cycle.

Oceanic production of calcium carbonate is conventionally attributed to marine plankton (coccolithophores and foraminifera). Here we report that marine fish produce precipitated carbonates within their intestines and excrete these at high rates. When combined with estimates of global fish biomass, this suggests that marine fish contribute 3 to 15% of total oceanic carbonate production. Fish carbonates have a higher magnesium content and solubility than traditional sources, yielding faster dissolution with depth. This may explain up to a quarter of the increase in titratable alkalinity within 1000 meters of the ocean surface, a controversial phenomenon that has puzzled oceanographers for decades. We also predict that fish carbonate production may rise in response to future environmental changes in carbon dioxide, and thus become an increasingly important component of the inorganic carbon cycle.

Normal development of the tomato clownfish Amphiprion frenatus: live imaging and in situ hybridization analyses of mesodermal and neurectodermal development.

The normal embryonic development of the tomato clownfish Amphiprion frenatus was analysed using live imaging and by in situ hybridization for detection of mesodermal and neurectodermal development. Both morphology of live embryos and tissue-specific staining revealed significant differences in the gross developmental programme of A. frenatus compared with better-known teleost fish models, in particular, initiation of somitogenesis before complete epiboly, initiation of narrowing of the neurectoderm (neurulation) before somitogenesis, relatively early pigmentation of melanophores at the 10-15 somite stage and a distinctive pattern of melanophore distribution. These results suggest evolutionary adaptability of the teleost developmental programme. The ease of obtaining eggs, in vitro culture of the embryo, in situ staining analyses and these reported characteristics make A. frenatus a potentially important model marine fish species for studying embryonic development, physiology, ecology and evolution.

Post-prandial alkaline tide in freshwater rainbow trout: effects of meal anticipation on recovery from acid-base and ion regulatory disturbances.

The post-feeding alkaline tide (elevated blood pH and HCO3-) has been well characterised in air-breathing animals, but to date this phenomenon has only been demonstrated in one piscine species, a marine elasmobranch. We have investigated the acid-base and ion regulatory responses of a freshwater teleost to voluntary feeding as well as to involuntary filling of the stomach via an indwelling gastric intubation tube. One group of rainbow trout (Oncorhynchus mykiss) were fed a 1% body mass ration of homogenised food via the gastric intubation tube. Another group fed voluntarily on a 1% body mass ration. Blood samples were taken via dorsal aortic catheters from fish in both groups before feeding and over the subsequent 72 h. Trout fed via the gastric intubation tube exhibited post-prandial metabolic alkalosis of the blood (pH and plasma HCO3- increases of up to approximately 0.2 pH units and 3 mmol l(-1), respectively), that was more than twofold greater than the voluntary feeding fish, and took three times as long to recover (72 versus 24 h). Arterial PCO2 was unchanged in both groups indicating that freshwater trout do not retain CO2 to compensate for a post-prandial alkaline tide. Although excretion of HCO3- to the water increased post-prandially, NH4+ excretion followed a similar pattern, such that net acid equivalent fluxes were unaffected. Thus, sites other than the gills or kidney must be responsible for recovery of blood acid-base status, with intestinal HCO3- secretion being a likely candidate. In addition, fish fed via the gastric intubation tube experienced a large (17 mmol l(-1)) but acute (6 h) drop in plasma chloride and a very large (53%) and long lasting decline in plasma magnesium concentration, that were absent in voluntarily feeding fish. These results further indicate a potentially important role for neuro-endocrine mediated mechanisms when fish feed voluntarily, in promoting the earlier initiation of compensatory responses that regulate blood ion levels and acid-base status. This aspect should also be considered when interpreting studies on other aspects of post-prandial physiology, where force feeding by gavage is commonly used in preference to voluntary feeding.

Optimizing Rayleigh laser guide star range-gate depth during initial loop closing.

The use of a Rayleigh laser guide star (LGS) as a wavefront reference for adaptive optics (AO) allows complete control over the distance to, and depth of, the slice of the Rayleigh plume that is selected. By altering the LGS range-gate depth (RGD) and distance at three defined stages during closed-loop operations, the LGS performance can be optimized. For the given example of a 20 km LGS on a 4.2 m telescope the application of this technique would increase the permissible RGD from 200to930 m after optimization. This can allow either an increase in LGS altitude or an increase in wavefront sensor frame rate, thereby increasing AO system performance.

The integration of behaviour into comparative physiology.

Comparative physiology has traditionally focused on the physiological responses of animals to their physicochemical environment. In recent years, awareness has increased among physiologists of the potential for behavioural factors, such as the social environment of the animal, to affect physiological condition and responses. This recognition has led to an emerging trend within the field toward using multidisciplinary approaches that incorporate both behavioural and physiological techniques. Research areas in which the integrated study of behaviour and physiology has been particularly fruitful include the physiology of the social environment, sensory physiology and behaviour, and physiological constraints on behavioural ecology. The manner in which incorporating behavioural considerations has informed the physiological data collected is discussed for each of these areas using specific examples.

Pilot study of a home-based aerobic exercise program for sedentary cancer survivors treated with hematopoietic stem cell transplantation.

We report a pilot study of a home-based aerobic exercise program in a group of 17 adult hematopoietic stem cell transplant (HSCT) recipients. Participants had received no cancer treatment for at least 6 months and reported leisure time physical activity less than 20 min per day and fewer than three times a week during the previous month. Following baseline assessments of aerobic fitness, fatigue symptoms, and quality of life, participants were placed on home-based aerobic exercise programs consisting of 20-40 min of activity in the target heart rate zone (40-60% predicted heart rate reserve) delivered in three to five sessions per week for 12 weeks. Subjects were supplied with electronic heart rate monitors and we encouraged program adherence using weekly telephone contacts and exercise diaries. In all, 32 of the 42 qualified candidates consented (acceptance=76%). Of these, 17 kept appointments for baseline assessments, four did not complete the study (attrition=46%), and no exercise-related adverse events were reported. Scores on measures of aerobic fitness, fatigue severity, and physical well-being improved (signed ranks test; P<0.05) during program participation. Our findings suggest that individually prescribed, home-based aerobic exercise is an acceptable, safe, and potentially effective intervention for improving physical functioning and fatigue in sedentary HSCT recipients.

Bicarbonate secretion plays a role in chloride and water absorption of the European flounder intestine.

Experiments performed on isolated intestinal segments from the marine teleost fish, the European flounder (Platichthys flesus), revealed that the intestinal epithelium is capable of secondary active HCO3(-) secretion in the order of 0.2-0.3 micromol x cm(-2) x h(-1) against apparent electrochemical gradient. The HCO3(-) secretion occurs via anion exchange, is dependent on mucosal Cl(-), results in very high mucosal HCO3(-) concentrations, and contributes significantly to Cl(-) and fluid absorption. This present study was conducted under in vivo-like conditions, with mucosal saline resembling intestinal fluids in vivo. These conditions result in a transepithelial potential of -16.2 mV (serosal side negative), which is very different from the -2.2 mV observed under symmetrical conditions. Under these conditions, we found a significant part of the HCO3(-) secretion is fueled by endogenous epithelial CO2 hydration mediated by carbonic anhydrase because acetazolamide (10(-4) M) was found to inhibit HCO3(-) secretion and removal of serosal CO(2) was found not to influence HCO3(-) secretion. Reversal of the epithelial electrochemical gradient for Cl(-) (removal of serosal Cl(-)) and elevation of serosal HCO3(-) resulted in enhanced HCO3(-) secretion and enhanced Cl(-) and fluid absorption. Cl(-) absorption via an anion exchange system appears to partly drive fluid absorption across the intestine in the absence of net Na(+) absorption.

Binding and movement of silver in the intestinal epithelium of a marine teleost fish, the European flounder (Platichthys flesus).

The intestine has been indicated as a site of waterborne silver toxicity in marine fish and chronic effects at the intestine have been observed at concentrations far below acutely toxic level. Thus, models of silver toxicity to marine fish need to consider the intestine as a biotic ligand. The present study characterises binding of silver to the intestine of the European flounder (Platichthys flesus). Everted intestinal sacks were prepared and submersed in a solution mimicking the intestinal fluid of the fish at the acclimation salinity (21 per thousand). Silver was added as (110m)AgNO(3) or (110m)AgNO(3)/AgNO(3) mixtures at concentrations ranging from 1.6 to 950 nM total silver. Appearance of (110m)Ag was analysed in mucosal scrapings, muscle layers, and in the plasma saline on the serosal side of the intestine. The latter represented uptake into blood and other extra-intestinal compartments. Mucosal scrapings consisted of both epithelial cells and mucus and, thus contained adsorbed as well as absorbed silver. Most of the silver in mucosal scrapings was bound to mucus. There was no difference in silver binding between the anterior, mid, and posterior regions of the intestine. Concentration-dependency of silver binding was sigmoidal and saturated above 100 nM total silver. The saturable appearance of (110m)Ag in the plasma saline suggest that silver passage across the intestine is transcellular and carrier mediated. Mucus likely influences uptake of silver by altering its speciation from that in the lumen and by serving as physical barrier for silver binding to the brushborder membrane. A biotic ligand model for marine fish to silver may have to consider these interactions.

Diverse strategies for ion regulation in fish collected from the ion-poor, acidic Rio Negro.

We measured unidirectional ion fluxes of fish collected directly from the Rio Negro, an extremely dilute, acidic blackwater tributary of the Amazon. Kinetic analysis of Na(+) uptake revealed that most species had fairly similar J(max) values, ranging from 1,150 to 1,750 nmol g(-1) h(-1), while K(m) values varied to a greater extent. Three species had K(m) values <33 micromol L(-1), while the rest had K(m) values >or=110 micromol L(-1). Because of the extremely low Na(+) concentration of Rio Negro water, the differences in K(m) values yield very different rates of Na(+) uptake. However, regardless of the rate of Na(+) uptake, measurements of Na(+) efflux show that Na(+) balance was maintained at very low Na(+) levels (<50 micromol L(-1)) by most species. Unlike other species with high K(m) values, the catfish Corydoras julii maintained high rates of Na(+) uptake in dilute waters by having a J(max) value at least 100% higher than the other species. Corydoras julii also demonstrated the ability to modulate kinetic parameters in response to changes in water chemistry. After 2 wk in 2 mmol L(-1) NaCl, J(max) fell >50%, and K(m) dropped about 70%. The unusual acclimatory drop in K(m) may represent a mechanism to ensure high rates of Na(+) uptake on return to dilute water. As well as being tolerant of extremely dilute waters, Rio Negro fish generally were fairly tolerant of low pH. Still, there were significant differences in sensitivity to pH among the species on the basis of degree of stimulation of Na(+) efflux at low pH. There were also differences in sensitivity to low pH of Na(+) uptake, and two species maintained significant rates of uptake even at pH 3.5. When fish were exposed to low pH in Rio Negro water instead of deionized water (with the same concentrations of major ions), the effects of low pH were reduced. This suggests that high concentrations of dissolved organic molecules in the water, which give it its dark tea color, may interact with the branchial epithelium in some protective manner.

Intestinal iron uptake in the European flounder (Platichthys flesus).

Iron is an essential element because it is a key constituent of the metalloproteins involved in cellular respiration and oxygen transport. There is no known regulated excretory mechanism for iron, and homeostasis is tightly controlled via its uptake from the diet. This study assessed in vivo intestinal iron uptake and in vitro iron absorption in a marine teleost, the European flounder Platichthys flesus. Ferric iron, in the form (59)FeCl(3), was reduced to Fe(2+) by ascorbate, and the bioavailability of Fe(3+) and Fe(2+) were compared. In vivo Fe(2+) uptake was significantly greater than Fe(3+) uptake and was reduced by the iron chelator desferrioxamine. Fe(2+) was also more bioavailable than Fe(3+) in in vitro studies that assessed the temporal pattern and concentration-dependency of iron absorption. The posterior region, when compared with the anterior and mid regions of the intestine, was the preferential site for Fe(2+) uptake in vivo. In vitro iron absorption was upregulated in the posterior intestine in response to prior haemoglobin depletion of the fish, and the transport showed a Q(10) value of 1.94. Iron absorption in the other segments of the intestine did not correlate with haematocrit, and Q(10) values were lower. Manipulation of the luminal pH had no effect on in vitro iron absorption. The present study demonstrates that a marine teleost absorbs Fe(2+) preferentially in the posterior intestine. This occurs in spite of extremely high luminal bicarbonate concentrations recorded in vivo, which may be expected to reduce the bioavailability of divalent cations as a result of the precipitation as carbonates (e.g. FeCO(3)).

Mycobacterium immunogenum sp. nov., a novel species related to Mycobacterium abscessus and associated with clinical disease, pseudo-outbreaks and contaminated metalworking fluids: an international cooperative study on mycobacterial taxonomy.

PCR-restriction enzyme pattern analysis of a 439 bp hsp65 gene segment identified 113 unique isolates among non-pigmented rapidly growing mycobacteria (RGM) from clinical and environmental sources that failed to match currently recognized species patterns. This group represented 40% of isolates recovered from bronchoscope contamination pseudo-outbreaks, 0% of disease-associated nosocomial outbreaks and 4% of routine clinical isolates of the Mycobacterium abscessus/Mycobacterium chelonae group submitted to the Mycobacteria/Nocardia laboratory for identification. It is grouped within the Mycobacterium fortuitum complex, with growth in less than 7 d, absence of pigmentation, positive 3-d arylsulfatase reaction and growth on MacConkey agar without crystal violet. It exhibited overlapping biochemical, antimicrobial susceptibility and HPLC characteristics of M. abscessus and M. chelonae. By 16S rRNA gene sequencing, these isolates comprised a homogeneous group with a unique hypervariable region A sequence and differed by 8 and 10 bp, respectively, from M. abscessus and M. chelonae. Surprisingly, this taxon contained two copies of the ribosomal operon, compared with single copies in the two related species. By DNA-DNA hybridization, this new group exhibited <30% homology with recognized RGM species. The name Mycobacterium immunogenum sp. nov. is proposed for this new taxon.

In vitro activities of linezolid against multiple Nocardia species.

Linezolid was tested by broth microdilution against 140 clinical Nocardia isolates belonging to seven species. The MIC at which 50% of the strains are inhibited (MIC50) and MIC90 for all species other than Nocardia farcinica were 2 and 4 microg/ml. Linezolid is the first antimicrobial agent demonstrated to be active against all Nocardia species.

Activities of linezolid against rapidly growing mycobacteria.

Linezolid is an oxazolidinone available as an oral drug which has activity against most gram-positive bacteria. However, few species of the genus Mycobacterium have been studied. We tested 249 clinical isolates and 10 reference strains of rapidly growing mycobacteria for susceptibility to linezolid by broth microdilution. Clinical species included the Mycobacterium fortuitum group (n = 74), M. abscessus (n = 98), M. chelonae (n = 50), M. mucogenicum (n = 10), and M. fortuitum third biovariant complex (10). The modal MIC for M. mucogenicum was 1.0 microg/ml, and the MIC at which 90% of the isolates tested are inhibited (MIC(90)) was 4 microg/ml; the modal MIC for the M. fortuitum group was 4 microg/ml, and the MIC(90) was 16 microg/ml; the modal MIC for the M. fortuitum third biovariant complex was 4 microg/ml, and the MIC(90) was 8 microg/ml; the modal MIC for M. chelonae was 8 microg/ml, and the MIC(90) was 16 microg/ml; and the modal MIC for M. abscessus was 32 microg/ml, and the MIC(90) was 64 microg/ml. Based on peak levels of linezolid in serum of 15 to 20 microg/ml, we propose the following broth MIC breakpoints for these species: susceptible, < or = 8 microg/ml; moderately susceptible, 16 microg/ml; and resistant, > or =32 microg/ml). These studies demonstrate the excellent potential of linezolid for therapy of rapidly growing mycobacteria.

Temporal and spatial profiling of the modification of an electroactive polymeric interface using neutron reflectivity.

Electropolymerized films of the functionalized pyrrole, pentafluorophenyl-3-(pyrrol-1-yl)propionate (PFP), were reacted with a solution-phase nucleophile, ferrocene ethylamine. This reaction was chosen as a model representative of a postdeposition modification of the polymer membrane's properties. For the first time, a nondestructive method for direct chemical analysis of the reaction profile within the electrodeposited polymer membrane after nucleophilic substitution is presented. This was achieved through the application of in situ neutron reflectivity with supplementary analytical information concerning the film's chemical composition obtained from XPS, FT-IR, and electrochemical measurements. The results presented illustrate how, for a partially reacted film resulting from a short reaction time, the extent of reaction with ferrocene ethylamine is not homogeneous throughout the thickness of the film, but occurs predominantly at the polymer/solution interface. We show that the progress of the reaction within the polymer film is limited by the transport of reacting species in the dense regions of the membrane that are furthest from the solution interface. The data do not fit an alternative model in which there is spatially homogeneous progression of the reaction front throughout the bulk of the thin film polymer. Guided by the neutron reflectivity measurements, suitable modifications were made to the electrodeposition method to prepare films whose architecture resulted in faster rates of reaction.

Effects of pre-acclimation to aluminium on the physiology and swimming behaviour of juvenile rainbow trout (Oncorhynchus mykiss) during a pulsed exposure.

Anthropogenic acidification of the freshwater environment causes aluminium to be mobilised into the aquatic environment. When pH falls below 5.5, exposure to aluminium concentrations as low as 12.5 microg.l(-1) can cause serious physiological disturbances in freshwater fish. However, under constant laboratory exposures fish can acclimate and recover physiological status within 5-30 days. In reality, fish in the wild are likely to experience chronic sub-lethal exposure, with occasional elevations (pulses) to much higher levels. The experiment described here investigated the effects of an environmentally realistic, 4-day pulse exposure to a high level of aluminium (36 microg.l(-1)) in two groups of juvenile rainbow trout. One group was exposed to a lower level of aluminium (24 microg.l(-1)) for 16 days before and 10 days after the pulse ('aluminium-acclimated' fish). A second group was exposed to pH 5.2 alone for 16 days before and 10 days after the pulse ('aluminium-naïve' fish). A third group exposed to pH 5.2 alone for 30 days (no aluminium added) acted as controls. Triplicate groups of 24 juvenile rainbow trout (2.3-16.7 g) were randomly allocated to one of these three treatments. Swimming behaviour was monitored throughout and samples were taken on days 14, 20, 22, 26 and 30 for assessment of physiological status. No treatment effects were recorded in the control group (pH 5.2 alone). Fish in the 'aluminium-acclimated' treatment became hypo-active upon initiation of the exposure to 24 microg.l(-1) aluminium, but recovered after just 4 days of this exposure. Subsequent challenge on day 16 with the 36 microg.l(-1) aluminium 'pulse' caused these fish to became hypo-active again, but they recovered normal swimming behaviour whilst still subject to the 4-day pulse. The 'aluminium-naïve' fish also became hypo-active during the pulse exposure (36 microg.l(-1) aluminium). However, they did not exhibit any recovery of swimming behaviour, either during the pulse, or even 6 days after the cessation of the pulse, despite a rapid depuration of gill aluminium load (within 2 days of the pulse finishing). Mortality was low in the aluminium-acclimated fish (4%) and significantly higher in the aluminium-naïve fish (26%). Haematological disturbances were most extreme in the aluminium-naïve fish and had not recovered to control levels 6 days after the end of the pulse. This study provides new evidence, using behavioural responses, that previous exposure to low levels of aluminium may be an important factor abating the impact of aluminium on fish in the natural environment.

Long-term results of permanent indwelling wallstents for benign mid-ureteral strictures.

BACKGROUND: Benign ureteral strictures are a potentially difficult problem that typically has been solved by open surgery. However, minimally invasive methods would be preferable. PATIENTS AND METHODS: Three patients with benign ureteral strictures were treated with endoscopic placement of self-expanding permanent indwelling stents (Wallstents). The etiologies of the obstruction were multifactorial and included retroperitoneal fibrosis, stones, traumatic ureteroscopy, ureteral ischemia, and previous open surgery. RESULTS: One patient died with a functioning stent 1 year, 7 months after placement. The other two patients are doing well 5 years, 2 months and 5 years, 11 months afterward (mean 51 months). CONCLUSION: Insertion of a permanent indwelling self-expanding ureteral stent is relatively easy, and long-term successes are documented. Placement of Wallstents for benign ureteral strictures should be considered as a treatment alternative.