bluuebunny/crossref_metadata_2025 huggingface dataset:
Nutrient Digestibility of Cereal Grain Products and By‐products in Extruded Diets for Nile Tilapia
Authors: Guimarães Igo G. , Pezzato Luiz E. , Barros Margarida M. , Tachibana Leonardo
Published: December 2008

Apparent digestibility coefficients (ADCs) provide estimates of nutrient availability in feedstuffs and can be used as a tool for selecting ingredients to compound cost‐effective diets for fish. Extrusion process is one factor that could influence ADC values. Thus, a digestibility trial was undertaken to evaluate ADC of protein, energy, and dry matter, and apparent amino acid availability (AAAA) in five cereal grain products/by‐products (corn, wheat middlings, broken rice, rice bran, and sorghum) in compounded diets for Nile tilapia. Chromic oxide was used as an external inert marker. The digestibility values of energy and dry matter in ingredients, in decreasing order, were highest for broken rice (95.34 and 96.45%), sorghum (82.37 and 87.29%), corn (67.34 and 82.21%), rice bran (57.58 and 55.59%), and wheat middlings (48.94 and 45.88%). Protein digestibility value was higher for corn (72.86%) and the lowest value was observed for sorghum (56.77%), while broken rice, wheat middlings, and rice bran presented values ranging from 63.01 to 66.88%. AAAA values were higher for corn (70.05%) and the lowest methionine and cystine availability values were recorded for wheat middlings and broken rice, respectively. Broken rice appears as one of the most indicated ingredient for using in Nile tilapia diets because of its highest values of nutrient digestibility when compared to the other energetic sources. The use of this information should aid more precise and economic diet formulation for Nile tilapia.
Effects of Dietary Vitamin C on Blood Chemistry and Nonspecific Immune Response of Juvenile Red Sea Bream, Pagrus major
Authors: Ren Tongjun , Koshio Shunsuke , Uyan Orhan , Komilus Connie Fay , Yokoyama Saichiro , Ishikawa Manabu , Abdul Md Kadel
Published: December 2008

A trial was conducted to determine the effect of ascorbyl‐2‐monophosphate Na/Ca (AMP‐Na/Ca) on blood chemistry and nonspecific immune response of red sea bream juveniles. Test diets with three levels of AsA (free, 107, and 325 mg/kg diet) were fed to juvenile red sea bream (36.0 ± 1.3 g) two times a day for 3 wk. There were no significant differences in hematocrit, glucose, and blood urea nitrogen. Total cholesterol and triglyceride in plasma of fish fed AsA‐free diet was significantly (P < 0.05) higher than that of fish fed two other diets. There were no significant differences in serum albumin, total bilirubin, and total serum protein. Glutamyl oxaloacetic transaminase in serum of fish fed diets containing 107 and 325 mg of AsA were significantly (P < 0.05) lower than that of fish fed AsA‐free diet. Serum lysozyme activity (LA) of fish fed diets containing 107 and 325 mg of AsA were significantly (P < 0.05) higher than that of fish fed AsA‐free diet. There was no significant difference in mucus LA. The results mentioned above demonstrated that AMP‐Na/Ca is a bioavailable AsA source for red sea bream juveniles. Supplement of more than 107 mg AsA/kg in diets improved blood chemistry and nonspecific immune function of red sea bream juveniles.
Effects of Salinity on Biogenic Amines, Hemolymph Osmotic Pressure, and Activity of Gill’s Na+/K+‐ATPase in Charybdis japonica (Crustacea, Decapoda)
Authors: Hong‐Yu Liu , Lu‐Qing Pan , Debin Zheng
Published: December 2008

The effects of salinity on hemolymph osmotic pressure, gill Na+/K+‐ATPase activity and dopamine (DA), norepinephrine (NE), serotonin (5‐HT) in the gills, and hemolymph of the adult Charybdis japonica were studied. DA levels increased significantly (P < 0.05), while the NE and 5‐HT revealed contrary change in hemolymph and gills. The iso‐osmotic point of C. japonica (911.4 mOsm/kg) was at salinity of 27.87 ppt. The Na+/K+‐ATPase activity of gill showed negative correlation with salinity in the hypotonic environment (<27.87 ppt). The results of this experiment indicated that C. japonica had great capability to acclimate to low salinity.
Feeding Dietary Mannan Oligosaccharides to Juvenile Nile Tilapia, Oreochromis niloticus, Has No Effect on Hematological Parameters and Showed Decreased Feed Consumption
Authors: Sado Ricardo Yuji , Bicudo ÁLvaro José De Almeida , Cyrino José Eurico Possebon
Published: December 2008

Impaired immune system by environmental stressors can lead fishes to be more susceptible to diseases that limit the economic development of aquaculture systems. This study was set out to determine the effect of six levels of mannan oligosaccharides (MOS; ActiveMOS®; Biorigin, Lençois Paulista,
São Paulo
, Brazil) on the performance index and hematology of Nile tilapia, Oreochromis niloticus juveniles. Fish (13.62 g) were randomly distributed into 18 plastic aquaria (300 L; 20 fishes per aquarium) and fed during 45 d with a commercial diet supplemented with 0, 0.2, 0.4, 0.6, 0.8, and 1% dietary MOS, in a totally randomized design trial (n = 3); biometrical and hematological data were collected and analyzed. There were no significant differences in hematological parameters between fish fed control and MOS supplementation diets, and daily feed consumption (FC) decreased (P < 0.05) with increasing levels of dietary MOS. Dietary MOS did not increase leukocyte count and presented negative effects on FC of Nile tilapia. At 0.4% MOS supplementation, the individual weight gain was higher in absolute values but not different (P > 0.05) compared to control diet.
The Effects of Stressful Broodstock Handling on Hormonal Profiles and Reproductive Performance of Rhamdia quelen (Quoy & Gaimard) Females
Authors: Soso Auren Benk , Gil Barcellos Leonardo José , Ranzani‐Paiva Maria José , Kreutz Luiz Carlos , Quevedo Rosmari Mezzalira , Lima Marina , Bolognesida Silva Leonardo , Ritter Filipe , Bedin Alexandra Calliari , Finco Jovani Antônio
Published: December 2008

Abstract.— A stressful environment induces cortisol that might affect fish breeding and reproduction. In the present work, which aimed to mimic aquacultural conditions of the jundia (Rhamdia quelen) hatcheries in southern South America, females were submitted to normal or stressful handling and the effects of cortisol on serum levels of 17β‐estradiol (E2) and testosterone (T) were determined. In addition, the effect of stress on reproductive parameters such as eggs and swim‐up fry production was also measured. Eight females from a group submitted to stressful handling (SH) conditions and eight females from a group with normal handling (NH) conditions were captured for blood sampling at D 0 and at D 1, 10, 20, 30, and 40 of the experiment. A typical cortisol response was observed in the SH females group in that they presented higher cortisol level in contrast to the NH female group, in all days sampled, except at D 0. In the 10th and 20th d, the E2 levels were lower in SH females, but cortisol levels were higher, suggesting an effect of cortisol on E2 production and/or release. Stressful handling appeared to affect both the number and the quality of the gametes because a lower number of oocytes was stripped from SH females, and from SH fertilized eggs, a lower number of viable swim‐up fry was obtained to be transferred to earthen larviculture ponds. Taken together, the results indicated that stressful handling of broodstock impairs R. quelen reproduction.
Excitatory and inhibitory intermediate zone interneurons in pathways from feline group I and II afferents: differences in axonal projections and input
Authors: Bannatyne B. A. , Liu T. T. , Hammar I. , Stecina K. , Jankowska E. , Maxwell D. J.
Published: December 2008

The aim of the present study was to compare properties of excitatory and inhibitory spinal intermediate zone interneurons in pathways from group I and II muscle afferents in the cat. Interneurons were labelled intracellularly and their transmitter phenotypes were defined by using immunocytochemistry. In total 14 glutamatergic, 22 glycinergic and 2 GABAergic/glycinergic interneurons were retrieved. All interneurons were located in laminae V–VII of the L3–L7 segments. No consistent differences were found in the location, the soma sizes or the extent of the dendritic trees of excitatory and inhibitory interneurons. However, major differences were found in their axonal projections; excitatory interneurons projected either ipsilaterally, bilaterally or contralaterally, while inhibitory interneurons projected exclusively ipsilaterally. Terminal projections of glycinergic and glutamatergic cells were found within motor nuclei as well as other regions of the grey matter which include the intermediate region, laminae VII and VIII. Cells containing GABA/glycine had more restricted projections, principally within the intermediate zone where they formed appositions with glutamatergic axon terminals and unidentified cells and therefore are likely to be involved in presynaptic as well as postsynaptic inhibition. The majority of excitatory and inhibitory interneurons were found to be coexcited by group I and II afferents (monosynaptically) and by reticulospinal neurons (mono‐ or disynaptically) and to integrate information from several muscles. Taken together the morphological and electrophysiological data show that individual excitatory and inhibitory intermediate zone interneurons may operate in a highly differentiated way and thereby contribute to a variety of motor synergies.
The decrease in mature myostatin protein in male skeletal muscle is developmentally regulated by growth hormone
Authors: Oldham Jenny M. , Osepchook Claire C. , Jeanplong Ferenc , Falconer Shelley J. , Matthews Kenneth G. , Conaglen John V. , Gerrard David F. , Smith Heather K. , Wilkins Richard J. , Bass James J. , McMahon Christopher D.
Published: December 2008

Myostatin inhibits myogenesis and there is reduced abundance of the mature protein in skeletal muscles of adult male compared with female mice. This reduction probably occurs after translation, which suggests that it is a regulated mechanism to reduce the availability of myostatin in males. Reduced myostatin may, thereby, contribute to the development of sexually dimorphic growth of skeletal muscle. Our first objective was to determine if the decrease in mature myostatin protein occurs before the linear growth phase to aid growth, or afterwards to maintain the mass of adult muscle. Mice were killed from 2 to 32 weeks and the gastrocnemius muscle was excised. Myostatin mRNA increased from 2 to 32 weeks and was higher in males than females (P < 0.001). In contrast, mature protein decreased in males after 6 weeks (P < 0.001). Our second objective was to determine if growth hormone (GH) induces the decrease in mature myostatin protein. GH increased myostatin mRNA and decreased the abundance of mature protein in hypophysectomised mice (P < 0.05). Our final objective was to determine if the decrease in mature protein occurs in skeletal muscles of male Stat5b−/− mice (Stat5b mediates the actions of GH). As expected, mature myostatin protein was not reduced in Stat5b−/− males compared with females. However, myostatin mRNA remained higher in males than females irrespective of genotype. These data suggest that: (1) the decrease in mature myostatin protein is developmentally regulated, (2) GH acting via Stat5b regulates the abundance of mature myostatin and (3) GH acts via a non‐Stat5b pathway to regulate myostatin mRNA.
Modulation of the sympathetic response to acute hypoxia by the caudal ventrolateral medulla in rats
Authors: Mandel Daniel A. , Schreihofer Ann M.
Published: December 2008

Hypoxia elevates splanchnic sympathetic nerve activity (SNA) with differential effects during inspiration and expiration by unresolved central mechanisms. We examined the hypothesis that cardiovascular‐related neurones in the caudal ventrolateral medulla (CVLM) contribute to the complex sympathetic response to hypoxia. In chloralose‐anaesthetized, ventilated, vagotomized rats, acute hypoxia (10% O2, 60 s) evoked an increase in SNA (103 ± 12%) that was characterized by a decrease in activity during early inspiration followed by a prominent rise during expiration. Some recorded baro‐activated CVLM neurones (n= 13) were activated by hypoxia, and most of these neurones displayed peak activity during inspiration that was enhanced during hypoxia. In contrast, other baro‐activated CVLM neurones were inhibited during hypoxia (n= 6), and most of these neurones showed peak activity during expiration prior to the onset of hypoxia. Microinjection of the glutamate antagonist kynurenate into the CVLM eliminated the respiratory‐related fluctuations in SNA during hypoxia and exaggerated the magnitude of the sympathetic response. In contrast, microinjection of a GABAA antagonist (bicuculline or gabazine) into the CVLM dramatically attenuated the sympathetic response to hypoxia. These data suggest the response to hypoxia in baro‐activated CVLM neurones is related to their basal pattern of respiratory‐related activity, and changes in the activity of these neurones is consistent with a contribution to the respiratory‐related sympathetic responses to hypoxia. Furthermore, both glutamate and GABA in the CVLM contribute to the complex sympathetic response to acute hypoxia.
On the mechanisms that limit oxygen uptake during exercise in acute and chronic hypoxia: role of muscle mass
Authors: Calbet José A. L. , Rådegran Göran , Boushel Robert , Saltin Bengt
Published: December 2008

Peak aerobic power in humans () is markedly affected by inspired O2 tension (). The question to be answered in this study is what factor plays a major role in the limitation of muscle peak in hypoxia: arterial O2 partial pressure () or O2 content ()? Thus, cardiac output (dye dilution with Cardio‐green), leg blood flow (thermodilution), intra‐arterial blood pressure and femoral arterial‐to‐venous differences in blood gases were determined in nine lowlanders studied during incremental exercise using a large (two‐legged cycle ergometer exercise: Bike) and a small (one‐legged knee extension exercise: Knee) muscle mass in normoxia, acute hypoxia (AH) () and after 9 weeks of residence at 5260 m (CH). Reducing the size of the active muscle mass blunted by 62% the effect of hypoxia on in AH and abolished completely the effect of hypoxia on after altitude acclimatization. Acclimatization improved Bike peak exercise from 34 ± 1 in AH to 45 ± 1 mmHg in CH (P < 0.05) and Knee from 38 ± 1 to 55 ± 2 mmHg (P < 0.05). Peak cardiac output and leg blood flow were reduced in hypoxia only during Bike. Acute hypoxia resulted in reduction of systemic O2 delivery (46 and 21%) and leg O2 delivery (47 and 26%) during Bike and Knee, respectively, almost matching the corresponding reduction in . Altitude acclimatization restored fully peak systemic and leg O2 delivery in CH (2.69 ± 0.27 and 1.28 ± 0.11 l min−1, respectively) to sea level values (2.65 ± 0.15 and 1.16 ± 0.11 l min−1, respectively) during Knee, but not during Bike. During Knee in CH, leg oxygen delivery was similar to normoxia and, therefore, also in spite of a of 55 mmHg. Reducing the size of the active muscle mass improves pulmonary gas exchange during hypoxic exercise, attenuates the Bohr effect on oxygen uploading at the lungs and preserves sea level convective O2 transport to the active muscles. Thus, the altitude‐acclimatized human has potentially a similar exercising capacity as at sea level when the exercise model allows for an adequate oxygen delivery (blood flow ×), with only a minor role of per se, when is more than 55 mmHg.
Threshold behaviour of human axons explored using subthreshold perturbations to membrane potential
Authors: Burke David , Howells James , Trevillion Louise , McNulty Penelope A. , Jankelowitz Stacey K. , Kiernan Matthew C.
Published: December 2008

The present study explores the threshold behaviour of human axons and the mechanisms contributing to this behaviour. The changes in excitability of cutaneous afferents in the median nerve at the wrist were recorded to a long‐lasting subthreshold conditioning stimulus, with a waveform designed to maximize the contribution of currents active in the just‐subthreshold region. The conditioning stimulus produced a decrease in threshold that developed over 3–5 ms following the end of the depolarization and then decayed slowly, in a pattern similar to the recovery of axonal excitability following a discharge. To ensure that the conditioning stimulus did not activate low‐threshold axons, similar recordings were then made from single motor axons in the ulnar nerve at the elbow. The findings were comparable, and behaviour with the same pattern and time course could be reproduced by subthreshold stimuli in a model of the human axon. In motor axons, subthreshold depolarizing stimuli, 1 ms long, produced a similar increase in excitability, but the late hyperpolarizing deflection was less prominent. This behaviour was again reproduced by the model axon and could be explained by the passive properties of the nodal membrane and conventional Na+ and K+ currents. The modelling studies emphasized the importance of leak current through the Barrett–Barrett resistance, even in the subthreshold region, and suggested a significant contribution of K+ currents to the threshold behaviour of axons. While the gating of slow K+ channels is slow, the resultant current may not be slow if there are substantial changes in membrane potential. By extrapolation, we suggest that, when human axons discharge, nodal slow K+ currents will be activated sufficiently early to contribute to the early changes in excitability following the action potential.
Up‐regulation of the peroxiredoxin‐6 related metabolism of reactive oxygen species in skeletal muscle of mice lacking neuronal nitric oxide synthase
Authors: Da Silva‐Azevedo Luis , Jähne Sebastian , Hoffmann Christian , Stalder Daniel , Heller Manfred , Pries Axel R. , Zakrzewicz Andreas , Baum Oliver
Published: December 2008

Although neuronal nitric oxide synthase (nNOS) plays a substantial role in skeletal muscle physiology, nNOS‐knockout mice manifest an only mild phenotypic malfunction in this tissue. To identify proteins that might be involved in adaptive responses in skeletal muscle of knockout mice lacking nNOS, 2D‐PAGE with silver‐staining and subsequent tandem mass spectrometry (LC‐MS/MS) was performed using extracts of extensor digitorum longus muscle (EDL) derived from nNOS‐knockout mice in comparison to C57Bl/6 control mice. Six proteins were significantly (P≤ 0.05) more highly expressed in EDL of nNOS‐knockout mice than in that of C57 control mice, all of which are involved in the metabolism of reactive oxygen species (ROS). These included prohibitin (2.0‐fold increase), peroxiredoxin‐3 (1.9‐fold increase), Cu2+/Zn2+‐dependent superoxide dismutase (SOD; 1.9‐fold increase), heat shock protein β‐1 (HSP25; 1.7‐fold increase) and nucleoside diphosphate kinase B (2.6‐fold increase). A significantly higher expression (4.1‐fold increase) and a pI shift from 6.5 to 5.9 of peroxiredoxin‐6 in the EDL of nNOS‐knockout mice were confirmed by quantitative immunoblotting. The concentrations of the mRNA encoding five of these proteins (the exception being prohibitin) were likewise significantly (P≤ 0.05) higher in the EDL of nNOS‐knockout mice. A higher intrinsic hydrogen peroxidase activity (P≤ 0.05) was demonstrated in EDL of nNOS‐knockout mice than C57 control mice, which was related to the presence of peroxiredoxin‐6. The treatment of mice with the chemical NOS inhibitor l‐NAME for3 days induced a significant 3.4‐fold up‐regulation of peroxiredoxin‐6 in the EDL of C57 control mice (P≤ 0.05), but did not alter its expression in EDL of nNOS‐knockout mice. ESR spectrometry demonstrated the levels of superoxide to be 2.5‐times higher (P≤ 0.05) in EDL of nNOS‐knockout mice than in C57 control mice while an in vitro assay based on the emission of 2,7‐dichlorofluorescein fluorescence disclosed the concentration of ROS to be similar in both strains of mice. We suggest that the up‐regulation of proteins that are implicated in the metabolism of ROS, particularly of peroxiredoxin‐6, within skeletal muscles of nNOS‐knockout mice functionally compensates for the absence of nNOS in scavenging of superoxide.
Resynthesis of phosphatidylinositol 4,5‐bisphosphate mediates adaptation of the caffeine response in rat taste receptor cells
Authors: Zhao Fang‐li , Herness Scott
Published: December 2008

Caffeine, a prototypic bitter stimulus, produces several physiological actions on taste receptor cells that include inhibition of KIR and KV potassium currents and elevations of intracellular calcium. These responses display adaptation, i.e. their magnitude diminishes in the sustained presence of the stimulus. Levels of the membrane lipid phosphatidylinositol‐4,5‐bisphosphate (PIP2) are well known to modulate many potassium channels, activating the channel by stabilizing its open state. Here we investigate a putative relationship of KIR and KV with PIP2 levels hypothesizing that inhibition of these currents by caffeine might be allayed by PIP2 resynthesis. Using standard patch‐clamp techniques, recordings of either potassium current from rat posterior taste receptor cells produced essentially parallel results when PIP2 levels were manipulated pharmacologically. Increasing PIP2 levels by blocking phosphoinositide‐3 kinase with wortmannin or LY294002, or by blocking phospholipase C with U73122 all significantly increased the incidence of adaptation for both KIR and KV. Conversely, lowering PIP2 synthesis by blocking PI4K or using the PIP2 scavengers polylysine or bovine serum albumin reduced the incidence of adaptation. Adaptation could be modulated by activation of protein kinase C but not calcium calmodulin kinase. Collectively, these data support two highly novel conclusions: potassium currents in taste receptor cells are significantly modulated by PIP2 levels and PIP2 resynthesis may play a central role in the gustatory adaptation process at the primary receptor cell level.
Obligatory role for phosphatidylinositol 4,5‐bisphosphate in activation of native TRPC1 store‐operated channels in vascular myocytes
Authors: Saleh Sohag N. , Albert Anthony P. , Large William A.
Published: December 2008

In the present study the effect of phosphatidylinositol 4,5‐bisphosphate (PIP2) was studied on a native TRPC1 store‐operated channel (SOC) in freshly dispersed rabbit portal vein myocytes. Application of diC8‐PIP2, a water soluble form of PIP2, to quiescent inside‐out patches evoked single channel currents with a unitary conductance of 1.9 pS. DiC8‐PIP2‐evoked channel currents were inhibited by anti‐TRPC1 antibodies and these characteristics are identical to SOCs evoked by cyclopiazonic acid (CPA) and BAPTA‐AM. SOCs stimulated by CPA, BAPTA‐AM and the phorbol ester phorbol 12,13‐dibutyrate (PDBu) were reduced by anti‐PIP2 antibodies and by depletion of tissue PIP2 levels by pre‐treatment of preparations with wortmannin and LY294002. However, these reagents did not alter the ability of PIP2 to activate SOCs in inside‐out patches. Co‐immunoprecipitation techniques demonstrated association between TRPC1 and PIP2 at rest, which was greatly decreased by wortmannin and LY294002. Pre‐treatment of cells with PDBu, which activates protein kinase C (PKC), augmented SOC activation by PIP2 whereas the PKC inhibitor chelerythrine decreased SOC stimulation by PIP2. Co‐immunoprecipitation experiments provide evidence that PKC‐dependent phosphorylation of TRPC1 occurs constitutively and was increased by CPA and PDBu but decreased by chelerythrine. These novel results show that PIP2 can activate TRPC1 SOCs in native vascular myocytes and plays an important role in SOC activation by CPA, BAPTA‐AM and PDBu. Moreover, the permissive role of PIP2 in SOC activation requires PKC‐dependent phosphorylation of TRPC1.
Stifling of Crevice Corrosion in Alloy 22 During Constant Potential Tests
Authors: Rebak Raul B.
Published: December 2008

Artificially creviced Alloy 22 (N06022) may be susceptible to crevice corrosion in the presence of high-chloride aqueous solutions, especially at higher temperatures and at anodic potentials. The presence of oxyanions in the electrolyte, particularly nitrate, inhibits the nucleation and growth of crevice corrosion. The current results show that crevice corrosion will develop in Alloy 22 when a constant potential above the crevice repassivation potential is applied to a creviced specimen. The analyses of the current output showed the presence of three characteristic domains: (1) passivation or induction time, (2) nucleation and growth, and (3) stifling and arrest. That is, under the tested conditions, crevice corrosion did initiate but after it reached a critical stage of growth, further damage stalled and the output anodic current returned to the passive values before the nucleation of the attack.
High Temperature Rotors: Failure Mechanisms and Remnant Life Assessment
Authors: Zhang Xiaoling
Published: December 2008

This paper presents the common failure mechanisms of high temperature rotors and the engineering approaches to their remnant life prediction. In fatigue crack growth at the rotor bore, cracks from original forging defects or induced during long service life may grow under cyclic loading to its critical size causing fast fracture. In fatigue-creep interaction at the shaft surface, high tensile residual stress relaxation under high operating temperature causes creep crack initiation. The cracks may then grow under the combination of cyclic loading and high operating temperature. Remnant creep life at the center of the rotor is based on the time while accumulated creep strain reaches its threshold level. Creep rupture could occur at other locations such as the outside surface of the shaft at disks∕shaft radii or blade fixings. Finite element analyses were carried out to analyze stresses, temperature transients, creep strain, and reference stress for creep rupture. Fracture mechanics analyses with R5 and R6 approaches were used to estimate the crack initiation and growth rates, the critical crack sizes, and the type of the failure. Appropriate Paris law and Norton creep laws were used for fatigue and creep crack growth. Depending on the failure mechanism, a rotor’s remnant life is defined in terms of allowable starts and operating hours.
Interaction Between Acoustic Resonance and Fluidelastic Instability in a Normal Triangular Tube Array
Authors: Mahon John , Meskell Craig
Published: December 2008

The interaction between acoustic resonance and damping controlled fluidelastic instability (FEI) in a normal triangular tube array (P∕d=1.32) has been investigated. The duct acoustics were excited with speakers placed adjacent to the tube array to artificially replicate flow-induced acoustic resonance. The paper deals with the effect on the rms level of tube vibration of three independent parameters: imposed acoustic sound pressure level, freestream flow velocity, and structural damping. A fall in the FEI vibration amplitude with increasing sound pressure level in the tube array has been observed. In addition, the imposed acoustic field delays the onset of damping controlled fluidelastic instability. The effects of flow velocity and structural damping in conjunction with acoustic resonance on the rms of tube displacement are discussed. While the current study has clearly captured the phenomenon of interaction between the fluidelastic motion at approximately 10Hz and the acoustic field at approximately 1kHz, it is not apparent what the physical mechanism at work might be.
Quantitative Estimation of the Growth of Environmentally Assisted Cracks at Flaws in Light Water Reactor Components
Authors: Xue H. , Sato Y. , Shoji T.
Published: December 2008

Since environmentally assisted cracking (EAC) is an important degradation mechanism affecting the structural materials of nuclear power plants, numerous EAC experiments have been performed in the past three decades using standard specimens in simulated high temperature water environments to evaluate the various core materials used in light water reactors (LWRs). However, the environment, the condition of the material, and the mechanical properties near flaws in LWR components are not absolutely equivalent to those near the crack tip in standard specimens; thus, more research needs to be done before EAC growth in an actual LWR component can be accurately estimated using existing experimental EAC data. By combining the film slip-dissolution/oxidation model with the elastic-plastic finite element method and existing experimental EAC data, we have derived a method by which an estimation of EAC growth at flaws in actual LWR components can be made. In this paper we propose and discuss the use of this method. The results show that this new method basically concurs with the Fracture Research Institute (FRI) model in evaluating EAC growth across a semi-elliptic crack front under a simple tensile load and is also in approximate agreement with the experimental results obtained in evaluating EAC growth along a semi-elliptic crack front under complex loading conditions. The approach is expected to form a bridge between predicting EAC growth rate in core materials and evaluating EAC growth in key structural components in LWRs, and it is also expected that it can be used as a pre-analytical tool for EAC experiments using nonstandard specimens.
Analytical Modeling of Hydraulically Expanded Tube-To-Tubesheet Joints
Authors: Laghzale Nor Eddine , Bouzid Abdel-Hakim
Published: December 2008

The loss of the initial tightness during service is one of the major causes of failure of tube-to-tubesheet joints. The initial residual contact pressure and its variation during the lifetime of the joint are among the parameters to blame. A reliable assessment of the initial contact pressure value requires accurate and rigorous modeling of the elastoplastic behavior of the tube and the tubesheet during the expansion process. This paper deals with the development of a new analytical model used to accurately predict the residual contact pressure resulting from a hydraulic expansion process. The analytical model is based on the elastic perfectly plastic material behavior of the tube and the tubesheet and the interaction between these two elements of the expanded joint. The model results have been compared and validated with those of the more accurate finite element analysis models. Additional comparisons have been made with existing methods.
Effect of Precompression on Ovality of Pipe After Bending
Authors: Kale A. V. , Thorat H. T.
Published: December 2008

Ovality is a main defect in all pipe bending techniques. An objective of the work is to control ovality in pipe bending. A new concept is suggested for reducing the flattening or ovality. Based on the concept, a mechanism is developed for bending pipes. This mechanism has provisions for precompression of the pipe along the directrix of maximum deformation during bending. Experimentation is carried out on this mechanism and dimensions are measured at 13 discrete places along the length of the pipe. Percentage ovality is computed using experimental results. It is justified by using equations of radius and displacement functions. Minimization of potential energy by sequential search method is done. The methodical approach is presented in this paper. Results show that precompression reduces ovality of the pipe after bending.
Rate Dependence and Short-Term Creep Behavior of a Thermoset Polymer at Elevated Temperature
Authors: Falcone C. M. , Ruggles-Wrenn M. B.
Published: December 2008

The inelastic deformation behavior of PMR-15 neat resin, a high-temperature thermoset polymer, was investigated at 288°C. The effect of loading rate on monotonic stress-strain behavior as well as the effect of prior stress rate on creep behavior were explored. Positive nonlinear rate sensitivity was observed in monotonic loading. Creep response was found to be significantly influenced by prior stress rate. The effect of loading history on creep was studied in stepwise creep tests, where specimens were subjected to a constant stress rate loading followed by unloading to zero stress with intermittent creep periods on both loading and unloading paths. The strain-time response was strongly influenced by prior deformation history. Negative creep was observed on the unloading path. In addition, the behavior of the material was characterized in terms of a nonlinear viscoelastic model by means of creep and recovery tests at 288°C. The model was employed to predict the response of the material under monotonic loading/unloading and multistep load histories.
Inhibition of Inositol Phosphorylceramide Synthase by the Cyclic Peptide Aureobasidin A
Authors: Aeed Paul A. , Young Casey L. , Nagiec Marek M. , Elhammer Åke P.
Published: December 2008

By using a detergent-washed membrane preparation, the interaction of the fungal natural product inhibitor aureobasidin A (AbA) with inositol phosphorylceramide synthase (IPC synthase) was studied by kinetic analysis of wild-type and mutant enzyme-catalyzed reactions. AbA inhibited the wild-type enzyme from both
Candida albicans
and
Saccharomyces cerevisiae
in an irreversible, time-dependent manner, with apparent

K
i

values of 183 and 234 pM, respectively. Three synthetic chemistry-derived AbA derivatives, PHA-533179, PHA-556655, and PHA-556656, had affinities 4 to 5 orders of magnitude lower and were reversible inhibitors that competed with the donor substrate phosphatidylinositol (PI). AbA was a reversible, apparently noncompetitive inhibitor, with a

K
i

of 1.4 μM, of the IPC synthase from an AbA-resistant
S. cerevisiae
mutant. The

K
m

values for both substrates (ceramide and PI) were similar when they interacted with the mutant and the wild-type enzymes. By contrast, the
V
max
for the mutant enzyme was less than 10% of that for the wild-type enzyme. A comparison of the results obtained with AbA with those obtained with two other natural products inhibitors, rustmicin and khafrefungin, revealed that while rustmicin appeared to be a reversible, noncompetitive inhibitor of the wild-type enzyme, with a

K
i

of 16.0 nM, khafrefungin had the kinetic properties of a time-dependent inhibitor and an apparent

K
i

of 0.43 nM. An evaluation of the efficiencies of these compounds as inhibitors of the mutant enzyme revealed for both a drop in the apparent affinity for the enzyme of more than 2 orders of magnitude.
Methicillin-Resistant and -Susceptible
Staphylococcus aureus
Strains of Clonal Lineages ST398 and ST9 from Swine Carry the Multidrug Resistance Gene
cfr
Authors: Kehrenberg Corinna , Cuny Christiane , Strommenger Birgit , Schwarz Stefan , Witte Wolfgang
Published: December 2008

Methicillin-resistant
Staphylococcus aureus
clonal lineage ST398 and methicillin-susceptible lineage ST9 strains have their main reservoir in swine but can colonize and cause infections in humans. The phenicol/lincosamide/oxazolidinone/pleuromutilin/streptogramin A multidrug resistance gene
cfr
was detected in isolates of both clonal lineages, rendering a spread to humans with exposure to swine farming possible.
Bacterial Diversity in a Mine Water Treatment Plant
Authors: Heinzel Elke , Hedrich Sabrina , Janneck Eberhard , Glombitza Franz , Seifert Jana , Schlömann Michael
Published: December 2008

We investigated the microbial community in a pilot plant for treatment of acid mine water by biological ferrous iron oxidation using clone library analysis and calculated statistical parameters for further characterization. The microbial community in the plant was conspicuously dominated by a group of
Betaproteobacteria
affiliated with “
Ferribacter polymyxa
”.
Regulation of Carotenogenesis and Secondary Metabolism by Nitrogen in Wild-Type
Fusarium fujikuroi
and Carotenoid-Overproducing Mutants
Authors: Rodríguez-Ortiz Roberto , Limón M. Carmen , Avalos Javier
Published: December 2008

The fungus
Fusarium fujikuroi
(
Gibberella fujikuroi
MP-C) produces metabolites of biotechnological interest, such as gibberellins, bikaverins, and carotenoids. Gibberellin and bikaverin productions are induced upon nitrogen exhaustion, while carotenoid accumulation is stimulated by light. We evaluated the effect of nitrogen availability on carotenogenesis in comparison with bikaverin and gibberellin production in the wild type and in carotenoid-overproducing mutants (
carS
). Nitrogen starvation increased carotenoid accumulation in all strains tested. In
carS
strains, gibberellin and bikaverin biosynthesis patterns differed from those of the wild type and paralleled the expression of key genes for both pathways, coding for geranylgeranyl pyrophosphate (GGPP) and kaurene synthases for the former and a polyketide synthase for the latter. These results suggest regulatory connections between carotenoid biosynthesis and nitrogen-controlled biosynthetic pathways in this fungus. Expression of gene
ggs1
, which encodes a second GGPP synthase, was also derepressed in the
carS
mutants, suggesting the participation of Ggs1 in carotenoid biosynthesis. The
carS
mutations did not affect genes for earlier steps of the terpenoid pathway, such as
fppS
or
hmgR
. Light induced carotenoid biosynthesis in the wild type and
carRA
and
carB
levels in the wild-type and
carS
strains irrespective of nitrogen availability.
Bioreduction with Efficient Recycling of NADPH by Coupled Permeabilized Microorganisms
Authors: Zhang Wei , O'Connor Kevin , Wang Daniel I. C. , Li Zhi
Published: December 2008

The glucose dehydrogenase (GDH) from
Bacillus subtilis
BGSC 1A1 was cloned and functionally expressed in
Escherichia coli
BL21(pGDH1) and XL-1 Blue(pGDH1). Controlled permeabilization of recombinant
E. coli
BL21 and XL-1 Blue with EDTA-toluene under optimized conditions resulted in permeabilized cells with specific activities of 61 and 14 U/g (dry weight) of cells, respectively, for the conversion of NADP
+
to NADPH upon oxidation of glucose. The permeabilized recombinant strains were more active than permeabilized
B. subtilis
BGSC 1A1, did not exhibit NADPH/NADH oxidase activity, and were useful for regeneration of both NADH and NADPH. Coupling of permeabilized cells of
Bacillus pumilus
Phe-C3 containing an NADPH-dependent ketoreductase and an
E. coli
recombinant expressing GDH as a novel biocatalytic system allowed enantioselective reduction of ethyl 3-keto-4,4,4-trifluorobutyrate with efficient recycling of NADPH; a total turnover number (TTN) of 4,200 mol/mol was obtained by using
E. coli
BL21(pGDH1) as the cofactor-regenerating microorganism with initial addition of 0.005 mM NADP
+
. The high TTN obtained is in the practical range for producing fine chemicals. Long-term stability of the permeabilized cell couple and a higher product concentration were demonstrated by 68 h of bioreduction of ethyl 3-keto-4,4,4-trifluorobutyrate with addition of 0.005 mM NADP
+
three times; 50.5 mM (
R
)-ethyl 3-hydroxy-4,4,4-trifluorobutyrate was obtained with 95% enantiomeric excess, 84% conversion, and an overall TTN of 3,400 mol/mol. Our method results in practical synthesis of (
R
)-ethyl 3-hydroxy-4,4,4-trifluorobutyrate, and the principle described here is generally applicable to other microbial reductions with cofactor recycling.
Detection and Quantification of Noroviruses in Shellfish
Authors: Le Guyader Françoise S. , Parnaudeau Sylvain , Schaeffer Julien , Bosch Albert , Loisy Fabienne , Pommepuy Monique , Atmar Robert L.
Published: December 2008

Noroviruses (NoVs) are the most common viral agents of acute gastroenteritis in humans, and high concentrations of NoVs are discharged into the environment. As these viruses are very resistant to inactivation, the sanitary consequences are contamination of food, including molluscan shellfish. There are four major problems with NoV detection in shellfish samples: low levels of virus contamination, the difficulty of efficient virus extraction, the presence of interfering substances that inhibit molecular detection, and NoV genetic variability. The aims of this study were to adapt a kit for use with a method previously shown to be efficient for detection of NoV in shellfish and to use a one step real-time reverse transcription-PCR method with addition of an external viral control. Comparisons of the two methods using bioaccumulated oysters showed that the methods reproducibly detected similar levels of virus in oyster samples. Validation studies using naturally contaminated samples also showed that there was a good correlation between the results of the two methods, and the variability was more attributable to the level of sample contamination. Magnetic silica very efficiently eliminated inhibitors, and use of extraction and amplification controls increased quality assurance. These controls increased the confidence in estimates of NoV concentrations in shellfish samples and strongly supported the conclusion that the results of the method described here reflected the levels of virus contamination in oysters. This approach is important for food safety and is under evaluationfor European regulation.
Antibacterial Effects of Grape Extracts onHelicobacter pylori
Authors: Brown Joseph C. , Huang Guohui , Haley-Zitlin Vivian , Jiang Xiuping
Published: December 2008

Anti-Helicobacter pyloriactivities were determined by agar dilution, confocal laser scanning microscopy, and cell proliferation assays following treatment with various grape extracts. Muscadine grape skin possessed the strongest activity, followed by grape synergy (skin and seed) and seed, suggesting that higher phenolic levels do not necessarily determine overall anti-H. pyloriefficacy.
Discovery of Stable and Variable Differences in the
Mycobacterium avium
subsp.
paratuberculosis
Type I, II, and III Genomes by Pan-Genome Microarray Analysis
Authors: Castellanos Elena , Aranaz Alicia , Gould Katherine A. , Linedale Richard , Stevenson Karen , Alvarez Julio , Dominguez Lucas , de Juan Lucia , Hinds Jason , Bull Tim J.
Published: December 2008

Mycobacterium avium
subsp.
paratuberculosis
is an important animal pathogen widely disseminated in the environment that has also been associated with Crohn's disease in humans. Three
M. avium
subsp.
paratuberculosis
genomotypes are recognized, but genomic differences have not been fully described. To further investigate these potential differences, a 60-mer oligonucleotide microarray (designated the MAPAC array), based on the combined genomes of
M. avium
subsp.
paratuberculosis
(strain K-10) and
Mycobacterium avium
subsp.
hominissuis
(strain 104), was designed and validated. By use of a test panel of defined
M. avium
subsp.
paratuberculosis
strains, the MAPAC array was able to identify a set of large sequence polymorphisms (LSPs) diagnostic for each of the three major
M. avium
subsp.
paratuberculosis
types.
M. avium
subsp.
paratuberculosis
type II strains contained a smaller genomic complement than
M. avium
subsp.
paratuberculosis
type I and
M. avium
subsp.
paratuberculosis
type III genomotypes, which included a set of genomic regions also found in
M. avium
subsp.
hominissuis
104. Specific PCRs for genes within LSPs that differentiated
M. avium
subsp.
paratuberculosis
types were devised and shown to accurately screen a panel (
n
= 78) of
M. avium
subsp.
paratuberculosis
strains. Analysis of insertion/deletion region INDEL12 showed deletion events causing a reduction in the complement of mycobacterial cell entry genes in
M. avium
subsp.
paratuberculosis
type II strains and significantly altering the coding of a major immunologic protein (MPT64) associated with persistence and granuloma formation. Analysis of MAPAC data also identified signal variations in several genomic regions, termed variable genomic islands (vGIs), suggestive of transient duplication/deletion events. vGIs contained significantly low GC% and were immediately flanked by insertion sequences, integrases, or short inverted repeat sequences. Quantitative PCR demonstrated that variation in vGI signals could be associated with colony growth rate and morphology.
Public Health Assessment of
Salmonella enterica
Serovar Enteritidis Inactivated-Vaccine Treatment in Layer Flocks
Authors: Toyota-Hanatani Yukiko , Ekawa Tomoya , Ohta Hiroaki , Igimi Shizunobu , Hara-Kudo Yukiko , Sasai Kazumi , Baba Eiichiroh
Published: December 2008

Although there have been several reports on the efficacy assessment of a
Salmonella enterica
serovar Enteritidis vaccine against intestinal and parenchymatous organ diseases of laying hens, no public health risk characterization of its long-term effect on eggs has been reported. In this study, we attempted to assess the public health effect of an inactivated
S. enterica
serovar Enteritidis vaccine against serovar Enteritidis contamination of chicken eggs. We analyzed serovar Enteritidis isolation test results from four windowless farms in which inactivated-vaccine administration was initiated based on the sanitary monitoring program of a farm. When flocks with and without
S. enterica
serovar Enteritidis vaccine treatments were mixed, the application of an inactivated serovar Enteritidis vaccine decreased the most probable number (MPN) of bacteria by at least 100-fold in broken (liquid) egg samples positive for serovar Enteritidis, although a statistical difference between those MPNs could not be obtained. The isolation frequency after the vaccine application was less than 1/10 (
P
< 0.01). No
S. enterica
serovar Enteritidis bacteria were isolated approximately 1 year after all of the chickens had received the inactivated serovar Enteritidis vaccine. It was suggested that an adequate administration of an inactivated serovar Enteritidis vaccine reduced the contamination risk of eggs (the number of isolated serovar Enteritidis cells and detection frequency) compared to the contamination risk of eggs laid by nonvaccinated hens.
Metabolomic Investigation of the Bacterial Response to a Metal Challenge
Authors: Tremaroli Valentina , Workentine Matthew L. , Weljie Aalim M. , Vogel Hans J. , Ceri Howard , Viti Carlo , Tatti Enrico , Zhang Ping , Hynes Alexander P. , Turner Raymond J. , Zannoni Davide
Published: December 2008

Pseudomonas pseudoalcaligenes
KF707 is naturally resistant to the toxic metalloid tellurite, but the mechanisms of resistance are not known. In this study we report the isolation of a KF707 mutant (T5) with hyperresistance to tellurite. In order to characterize the bacterial response and the pathways leading to tolerance, we utilized Phenotype MicroArray technology (Biolog) and a metabolomic technique based on nuclear magnetic resonance spectroscopy. The physiological states of KF707 wild-type and T5 cells exposed to tellurite were also compared in terms of viability and reduced thiol content. Our analyses showed an extensive change in metabolism upon the addition of tellurite to KF707 cultures as well as different responses when the wild-type and T5 strains were compared. Even in the absence of tellurite, T5 cells displayed a “poised” physiological status, primed for tellurite exposure and characterized by altered intracellular levels of glutathione, branched-chain amino acids, and betaine, along with increased resistance to other toxic metals and metabolic inhibitors. We conclude that hyperresistance to tellurite in
P. pseudoalcaligenes
KF707 is correlated with the induction of the oxidative stress response, resistance to membrane perturbation, and reconfiguration of cellular metabolism.