bluuebunny/crossref_metadata_2025 huggingface dataset:
INFLUENCE OF NITROGEN FLOW RATE ON FRICTION COEFFICIENT AND SURFACE ROUGHNESS OF TiN COATINGS DEPOSITED ON TOOL STEEL USING ARC METHOD
Authors: HAMZAH ESAH , OURDJINI ALI , ALI MUBARAK , AKHTER PARVEZ , HJ. MOHD TOFF MOHD RADZI , ABDUL HAMID MANSOR
Published: October 2007

In the present study, the effect of various N 2 gas flow rates on friction coefficient and surface roughness of TiN -coated D2 tool steel was examined by a commercially available cathodic arc physical vapor deposition (CAPVD) technique. A Pin-on-Disc test was carried out to study the Coefficient of friction (COF) versus sliding distance. A surface roughness tester measured the surface roughness parameters. The minimum values for the COF and surface roughness were recorded at a N 2 gas flow rate of 200 sccm. The increase in the COF and surface roughness at a N 2 gas flow rate of 100 sccm was mainly attributed to an increase in both size and number of titanium particles, whereas the increase at 300 sccm was attributed to a larger number of growth defects generated during the coating process. These ideas make it possible to optimize the coating properties as a function of N 2 gas flow rate for specific applications, e.g. cutting tools for automobiles, aircraft, and various mechanical parts.
SELF-LIMITING GROWTH OF TITANIUM SILICATE AND EFFECTS OF THERMAL ANNEALING ON THE ELECTRICAL PROPERTIES OF TITANIUM SILICATE/SiO2
Authors: LEE SEUNGJAE , YONG KIJUNG
Published: October 2007

Titanium silicate thin films were deposited using self-limiting atomic layer growth technique. Grown films showed smooth film surface morphology. As deposited, 8 nm-thick film surface showed an RMS value of 0.43 nm and annealed film showed a smoother surface having RMS of 0.2 nm. Electrical properties of titanium silicate/ SiO 2 bilayer were investigated using capacitance–voltage (C–V) and leakage current-voltage (I–V) measurements. The grown films showed high dielectric properties with low impurity contents and low leakage currents. Upon annealing at 800°C, capacitance slightly decreased, which is likely due to the interfacial reactions. Generally thermal annealing decreased hysteresis in C–V results.
STRUCTURE, THERMAL STABILITY, AND CO ADSORPTION PROPERTIES OF PD NANOPARTICLES SUPPORTED ON AN ULTRA-THIN SiO2 FILM
Authors: LU J.-L. , WEISSENRIEDER J. , KAYA S. , GAO H.-J. , SHAIKHUTDINOV S. , FREUND H.-J.
Published: October 2007

Nucleation, growth, and thermal stability of Pd particles vapor-deposited on an ultra-thin crystalline silica film grown on Mo (112) have been studied by scanning tunneling microscopy, X-ray photoelectron spectroscopy, infrared reflection absorption spectroscopy, and temperature-programmed desorption of CO . No preferential nucleation of Pd on the silica film is found at room temperature deposition: the hemispherical Pd nanoparticles are homogenously dispersed on the support at all coverages studied (0.01 - 1 ML (mono layer)). The Pd particles are resistant toward sintering up to 700 K as judged by STM; however, CO adsorption studies have revealed surface chemical modification at temperatures as low as 550 K. Strong morphological changes are observed above 800 K (ultimately resulting in elongated rectangular islands at ~1000 K), which is accompanied by strong alterations of CO adsorption properties. The results are rationalized in terms of Pd and Mo substrate interdiffusion at elevated temperatures, while the silica film basically preserves its structure.
OXIDATION RESISTANCE MECHANISM OFZrB2–Al2O3–Y2O3COMPOSITE PARTICLES
Authors: SONG J. G. , LI J. G. , SONG J. R. , ZHANG L. M.
Published: October 2007

Although ZrB2has some excellent performances, it is easily oxidized in the high-temperature air, which is deadly shortcoming as high-temperature materials. To increase the high-temperature performances of ZrB2, Al2O3and Y2O3particles are coated on the ZrB2surface to prepare ZrB2– Al2O3– Y2O3composite particles. The oxidation resistance mechanism of ZrB2– Al2O3– Y2O3composite particles is investigated by DTA-TG, TEM, and XRD. The surface of ZrB2particle is coated with compact Al2O3and Y2O3particles, which establishes the foundation to attain good oxidation resistance. ZrB2particle is mainly oxidized to increase the weight, from 600°C to 800°C. B2O3, obtained through the oxidization reaction, might coat on the surface of ZrB2particle to retard the oxidization reaction, which further increases the oxidation resistance. The oxidation resistance of coated ZrB2particle is far better than that of original ZrB2particle.
XPS STUDY OF INTERACTION OF TITANIUM SPECIES WITH DIFFERENT INTERNAL ELECTRON DONORS ON Z–N CATALYSTS
Authors: ZHAO XI , ZHANG YING , SONG YANG , WEI GANG
Published: October 2007

TiCl 4/ MgCl 2, TiCl 4/ MgCl 2/donor catalysts and TiCl 4/donor complexes were prepared in this experiment; the donors are EB, DNBP, DBPG, DBW, PPDE, and BMMF respectively. Chemical states of Ti on the surface of MgCl 2-supported Z – N catalysts were analyzed with X-ray photoelectron spectroscopy (XPS). The interaction among components of a catalyst is characterized, and the function of internal donor in the catalyst was demonstrated according to the change of binding energy of Ti 2 p 3/2. We may conclude from the experiment that the kind of internal donors influence the electron density around titanium, and further the electron density around active titanium species effect catalyst activity to some extent. It was also noted that the interaction between internal donors and titanium is weakened remarkably by moisture and oxygen in ambient.
THE USE OF ARRHENIUS KINETIC MODEL TO PREDICT ACTIVATION ENERGIES IN HARDWOOD–WATER SYSTEMS
Authors: TURGUT SAHIN H.
Published: October 2007

In this study, water swelling coefficients and activation energies for eucalyptus and poplar woods were calculated. The swelling properties of both species appear to directly proportional dependence on temperature and its directions. In the tangential direction, the swelling rate coefficients of eucalyptus ranged from 0.30 to 0.69 are greater than that of poplar which ranged from 0.24 to 0.55. In comparison to average activation energy (Ea), poplar approximately have 2.6 kJ/mole higher Eathan eucalyptus (36.7 vs 39.3 kJ/mole). The comparison and the measured results reveal that the swelling response of both woods with temperature can be quite well predicted using Arrhenius kinetic theory.
Novel anti-oxidative role of calreticulin in protecting A549 human type II alveolar epithelial cells against hypoxic injury
Authors: Jia Lingyun , Xu Mingjiang , Zhen Wei , Shen Xun , Zhu Yi , Wang Wang , Wang Xian
Published: October 2007

Short-term hypoxic pretreatment is an effective approach to protect the lung from subsequent prolonged hypoxic injury under conditions such as lung transplantation, shock, and trauma. However, the signaling pathways are not well understood. By use of high-throughput, two-dimensional electrophoresis combined with mass spectrometry, we found that short-term hypoxic treatment upregulated calreticulin (CRT), an endoplasmic-reticulum stress protein, in A549 human type II alveolar epithelial cells. Genetic manipulation of CRT expression in A549 cells through small interferring RNA inhibition or overexpression demonstrated a positive correlation between CRT expression level and cell viability in subsequent prolonged hypoxia, which indicates that CRT is a key mediator of short-term hypoxia-induced cell protection. Importantly, CRT overexpression prevented reactive oxygen species (ROS) accumulation during prolonged hypoxia by inducing the expression of thioredoxin (TRX), an antioxidant, in A549 cells. Furthermore, CRT promoted the nuclear translocation of nuclear factor-E2-related factor 2, the transcription factor of TRX. Finally, overexpressing an inactive TRX mutant reversed the effects of CRT on ROS accumulation and cell protection. Our results demonstrate that CRT stimulates the anti-oxidant pathway and contributes to short-term hypoxia-induced protection in A549 type II alveolar epithelial cells, which may have potential therapeutic ramifications for hypoxic pulmonary diseases.
Upregulation of RGS4 and downregulation of CPI-17 mediate inhibition of colonic muscle contraction by interleukin-1β
Authors: Hu Wenhui , Mahavadi Sunila , Li Fang , Murthy Karnam S.
Published: October 2007

The pro-inflammatory cytokine IL-1β contributes to the reduced contractile responses of gut smooth muscle observed in both animal colitis models and human inflammatory bowel diseases. However, the mechanisms are not well understood. The effects of IL-1β on the signaling targets mediating acetylcholine (ACh)-induced initial and sustained contraction were examined using rabbit colonic circular muscle strips and cultured muscle cells. The contraction was assessed through cell length decrease, myosin light chain (MLC20) phosphorylation, and activation of PLC-β and Rho kinase. Expression levels of the signaling targets were determined by Western blot analysis and real-time RT-PCR. Short interfering RNAs (siRNAs) for regulator of G protein signaling 4 (RGS4) were used to silence endogenous RGS4 in muscle strips or cultured muscle cells. IL-1β treatment of muscle strips inhibited both initial and sustained contraction and MLC20 phosphorylation in isolated muscle cells. IL-1β treatment increased RGS4 expression but had no effect on muscarinic receptor binding or Gαq expression. In contrast, IL-1β decreased the expression and phosphorylation of CPI-17 but had no effect on RhoA expression or ACh-induced Rho kinase activity. Upregulation of RGS4 and downregulation of CPI-17 by IL-1β in muscle strips were corroborated in cultured muscle cells. Knockdown of RGS4 by siRNA in both muscle strips and cultured muscle cells blocked the inhibitory effect of IL-1β on initial contraction and PLC-β activation, whereas overexpression of RGS4 inhibited PLC-β activation. These data suggest that IL-1β upregulates RGS4 expression, resulting in the inhibition of initial contraction and downregulation of CPI-17 expression during sustained contraction in colonic smooth muscle.
Tyrphostin A8 stimulates a novel trafficking pathway of apically endocytosed transferrin through Rab11-enriched compartments in Caco-2 cells
Authors: Norouziyan Fariba , Shen Wei-Chiang , Hamm-Alvarez Sarah F.
Published: October 2007

The potential application of transferrin receptors as delivery vehicles for transport of macromolecular drugs across intestinal epithelial cells is limited by several factors, including the low level of transferrin receptor-mediated transcytosis, particularly in the apical-to-basolateral direction. The GTPase inhibitor, AG10 (tyrphostin A8), has been shown previously to increase the apical-to-basolateral transcytosis of transferrin in Caco-2 cells. However, the mechanism of the increased transcytosis has not been established. In this report, the effect of AG10 on the trafficking of endocytosed transferrin among different endosomal compartments as well as the involvement of Rab11 in the intracellular trafficking of transferrin was investigated. Confocal microscopy studies showed a high level of colocalization of FITC-transferrin with Rab5 and Rab11 in Caco-2 cells pulsed at 16°C and 37°C, which indicated the presence of apically endocytosed FITC-transferrin in early endosomes and apical recycling endosomes at 16°C and 37°C, respectively. The effect of AG10 on the accumulation of transferrin within different endosomal compartment was studied, and an increase in the transcytosis and recycling of internalized 125I-labeled transferrin, as well as a decrease in cell-associated 125I-labeled transferrin, was observed in AG10-treated Caco-2 cells pulsed at 37°C for 30 min and chased for 30 min. Moreover, confocal microscopy showed that FITC-transferrin exhibited an increased level of colocalization with Rab11, but not with Rab5, in the presence of AG10. These results suggest an effect of AG10 on the later steps of transferrin receptor trafficking, which are involved in subsequent recycling, and possibly transcytosis, of endocytosed transferrin in Caco-2 cells.
Dysregulated pyruvate dehydrogenase complex in Zucker diabetic fatty rats
Authors: Schummer Christoph M. , Werner Ulrich , Tennagels Norbert , Schmoll Dieter , Haschke Guido , Juretschke Hans-Paul , Patel Mulchand S. , Gerl Martin , Kramer Werner , Herling Andreas W.
Published: October 2007

The mitochondrial pyruvate dehydrogenase complex (PDC) is inactivated in many tissues during starvation and diabetes. We investigated carbohydrate oxidation (CHO) and the regulation of the PDC in lean and obese Zucker diabetic fatty (ZDF) rats during fed and starved conditions as well as during an oral glucose load without and with pharmacologically reduced levels of free fatty acids (FFA) to estimate the relative contribution of FFA on glucose tolerance, CHO, and PDC activity. The increase in total PDC activity (20–45%) was paralleled by increased protein levels (∼2-fold) of PDC subunits in liver and muscle of obese ZDF rats. Pyruvate dehydrogenase kinase-4 (PDK4) protein levels were higher in obese rats, and consequently PDC activity was reduced. Although PDK4 protein levels were rapidly downregulated (57–62%) in both lean and obese animals within 2 h after glucose challenge, CHO over 3 h as well as the peak of PDC activity (1 h after glucose load) in liver and muscle were significantly lower in obese rats compared with lean rats. Similar differences were obtained with pharmacologically suppressed FFA by nicotinic acid, but with significantly improved glucose tolerance in obese rats, as well as increased CHO and delta increases in PDC activity (0–60 min) both in muscle and liver. These results demonstrated the suppressive role of FFA acids on the measured parameters. Furthermore, the results clearly demonstrate a rapid reactivation of PDC in liver and muscle of lean and obese rats after a glucose load and show that PDC activity is significantly lower in obese ZDF rats.
Intracisternal administration of transforming growth factor-β evokes fever through the induction of cyclooxygenase-2 in brain endothelial cells
Authors: Matsumura Shigenobu , Shibakusa Tetsuro , Fujikawa Teppei , Yamada Hiroyuki , Matsumura Kiyoshi , Inoue Kazuo , Fushiki Tohru
Published: October 2007

Transforming growth factor-β (TGF-β), a pleiotropic cytokine, regulates cell proliferation, differentiation, and apoptosis, and plays a key role in development and tissue homeostasis. TGF-β functions as an anti-inflammatory cytokine because it suppresses microglia and B-lymphocyte functions, as well as the production of proinflammatory cytokines. However, we previously demonstrated that the intracisternal administration of TGF-β induces fever like that produced by proinflammatory cytokines. In this study, we investigated the mechanism of TGF-β-induced fever. The intracisternal administration of TGF-β increased body temperature in a dose-dependent manner. Pretreatment with cyclooxygenase-2 (COX-2)-selective inhibitor significantly suppressed TGF-β-induced fever. COX-2 is known as one of the rate-limiting enzymes of the PGE2synthesis pathway, suggesting that fever induced by TGF-β is COX-2 and PGE2dependent. TGF-β increased PGE2levels in cerebrospinal fluid and increased the expression of COX-2 in the brain. Double immunostaining of COX-2 and von Willebrand factor (vWF, an endothelial cell marker) revealed that COX-2-expressing cells were mainly endothelial cells. Although not all COX-2-immunoreactive cells express TGF-β receptor, some COX-2-immunoreactive cells express activin receptor-like kinase-1 (ALK-1, an endothelial cell-specific TGF-β receptor), suggesting that TGF-β directly or indirectly acts on endothelial cells to induce COX-2 expression. These findings suggest a novel function of TGF-β as a proinflammatory cytokine in the central nervous system.
Monosodium glutamate-induced arcuate nucleus damage affects both natural torpor and 2DG-induced torpor-like hypothermia in Siberian hamsters
Authors: Pelz Kimberly M. , Routman David , Driscoll Joseph R. , Kriegsfeld Lance J. , Dark John
Published: October 2007

Siberian hamsters ( Phodopus sungorus) have the ability to express daily torpor and decrease their body temperature to ∼15°C, providing a significant savings in energy expenditure. Daily torpor in hamsters is cued by winterlike photoperiods and occurs coincident with the annual nadirs in body fat reserves and chronic leptin concentrations. To better understand the neural mechanisms underlying torpor, Siberian hamster pups were postnatally treated with saline or MSG to ablate arcuate nucleus neurons that likely possess leptin receptors. Body temperature was studied telemetrically in cold-acclimated (10°C) male and female hamsters moved to a winterlike photoperiod (10:14-h light-dark cycle) ( experiments 1 and 2) or that remained in a summerlike photoperiod (14:10-h light-dark cycle) ( experiment 3). In experiment 1, even though other photoperiodic responses persisted, MSG-induced arcuate nucleus ablations prevented the photoperiod-dependent torpor observed in saline-treated Siberian hamsters. MSG-treated hamsters tended to possess greater fat reserves. To determine whether reductions in body fat would increase frequency of photoperiod-induced torpor after MSG treatment, hamsters underwent 2 wk of food restriction (70% of ad libitum) in experiment 2. Although food restriction did increase the frequency of torpor in both MSG- and saline-treated hamsters, it failed to normalize the proportion of MSG-treated hamsters undergoing photoperiod-dependent torpor. In experiment 3, postnatal MSG treatments reduced the proportion of hamsters entering 2DG-induced torpor-like hypothermia by ∼50% compared with saline-treated hamsters (38 vs. 72%). In those MSG-treated hamsters that did become hypothermic, their minimum temperature during hypothermia was significantly greater than comparable saline-treated hamsters. We conclude that 1) arcuate nucleus mechanisms mediate photoperiod-induced torpor, 2) food-restriction-induced torpor may also be reduced by MSG treatments, and 3) arcuate nucleus neurons make an important, albeit partial, contribution to 2DG-induced torpor-like hypothermia.
Intracellular calcium plays a role as the second messenger of hypotonic stress in gene regulation of SGK1 and ENaC in renal epithelial A6 cells
Authors: Taruno Akiyuki , Niisato Naomi , Marunaka Yoshinori
Published: October 2007

In A6 cells, a renal cell line derived from Xenopus laevis, hypotonic stress stimulates the amiloride-sensitive Na+ transport. Hypotonic action on Na+ transport consists of two phases, a nongenomic early phase and a genomic delayed phase. Although it has been reported that, during the genomic phase, hypotonic stress stimulates transcription of Na+ transport-related genes, such as serum- and glucocorticoid-inducible kinase 1 (SGK1) and subunits of the epithelial Na+ channel (ENaC), increasing Na+ transport, the mechanism remains unknown. We focused the present study on the role of intracellular Ca2+ in hypotonicity-induced SGK1 and ENaC subunit transcription. Since hypotonic stress raises intracellular Ca2+ concentration in A6 cells, we hypothesized that Ca2+-dependent signals participate in the genomic action. Using real-time quantitative RT-PCR and Western blot techniques and measuring short-circuit currents, we observed that 1) BAPTA-AM and W7 blunted the hypotonicity-induced expression of SGK1 mRNA and protein, 2) ionomycin dose dependently stimulated expression of SGK1 mRNA and protein under an isotonic condition and the time course of the stimulatory effect of ionomycin on SGK1 mRNA was remarkably similar to that of hypotonic action on SGK1 mRNA, 3) hypotonic stress stimulated transcription of three ENaC subunits in an intracellular Ca2+-dependent manner, and 4) BAPTA-AM retarded the delayed phase of hypotonic stress-induced Na+ transport but had no effect on the early phase. These observations indicate for the first time that intracellular Ca2+ plays a role as the second messenger in hypotonic stress-induced Na+ transport by stimulating transcription of SGK1 and ENaC subunits.
Free radical stress-mediated loss ofKcnj10protein expression in stria vascularis contributes to deafness in Pendred syndrome mouse model
Authors: Singh Ruchira , Wangemann Philine
Published: October 2007

Pendred syndrome is due to loss-of-function mutations of Slc26a4, which codes for the HCO3−transporter pendrin. Loss of pendrin causes deafness via a loss of the K+channel Kcnj10 in stria vascularis and consequent loss of the endocochlear potential. Pendrin and Kcnj10 are expressed in different cell types. Here, we report that free radical stress provides a link between the loss of Kcnj10 and the loss of pendrin. Studies were performed using native and cultured stria vascularis from Slc26a4+/−and Slc26a4−/−mice as well as Chinese hamster ovary (CHO)-K1 cells. Kcnj10, oxidized proteins, and proteins involved in iron metabolism were quantified by Western blotting. Nitrated proteins were quantified by ELISA. Total iron was measured by ferrozine spectrophotometry and gene expression was quantified by qRT-PCR. At postnatal day 10 ( P10), stria vascularis from Slc26a4+/−and Slc26a4−/−mice expressed similar amounts of Kcnj10. Slc26a4−/−mice lost Kcnj10 expression during the next 5 days of development. In contrast, stria vascularis, obtained from P10 Slc26a4−/−mice and kept in culture for 5 days, maintained Kcnj10 expression. Stria vascularis from Slc26a4−/−mice was found to suffer from free radical stress evident by elevated amounts of oxidized and nitrated proteins and other changes in protein and gene expression. Free radical stress induced by 3-morpholinosydnonimine- N-ethylcarbamide was found to be sufficient to reduce Kcnj10 expression in CHO-K1 cells. These data demonstrate that free radical stress provides a link between loss of pendrin and loss of Kcnj10 in Slc26a4−/−mice and possibly in human patients suffering from Pendred syndrome.
Dominance of the Proximal Coordinate Frame in Determining the Locations of Hippocampal Place Cell Activity During Navigation
Authors: Siegel Jennifer J. , Neunuebel Joshua P. , Knierim James J.
Published: October 2007

The place-specific activity of hippocampal cells provides downstream structures with information regarding an animal's position within an environment and, perhaps, the location of goals within that environment. In rodents, recent research has suggested that distal cues primarily set the orientation of the spatial representation, whereas the boundaries of the behavioral apparatus determine the locations of place activity. The current study was designed to address possible biases in some previous research that may have minimized the likelihood of observing place activity bound to distal cues. Hippocampal single-unit activity was recorded from six freely moving rats as they were trained to perform a tone-initiated place-preference task on an open-field platform. To investigate whether place activity was bound to the room- or platform-based coordinate frame (or both), the platform was translated within the room at an “early” and at a “late” phase of task acquisition (Shift 1 and Shift 2). At both time points, CA1 and CA3 place cells demonstrated room-associated and/or platform-associated activity, or remapped in response to the platform shift. Shift 1 revealed place activity that reflected an interaction between a dominant platform-based (proximal) coordinate frame and a weaker room-based (distal) frame because many CA1 and CA3 place fields shifted to a location intermediate to the two reference frames. Shift 2 resulted in place activity that became more strongly bound to either the platform- or room-based coordinate frame, suggesting the emergence of two independent spatial frames of reference (with many more cells participating in platform-based than in room-based representations).
Contrast Sensitivity Is Enhanced by Expansive Nonlinear Processing in the Lateral Geniculate Nucleus
Authors: Duong Thang , Freeman Ralph D.
Published: October 2007

The firing rates of neurons in the central visual pathway vary with stimulus strength, but not necessarily in a linear manner. In the contrast domain, the neural response function for cells in the primary visual cortex is characterized by expansive and compressive nonlinearities at low and high contrasts, respectively. A compressive nonlinearity at high contrast is also found for early visual pathway neurons in the lateral geniculate nucleus (LGN). This mechanism affects processing in the visual cortex. A fundamentally related issue is the possibility of an expansive nonlinearity at low contrast in LGN. To examine this possibility, we have obtained contrast–response data for a population of LGN neurons. We find for most cells that the best-fit function requires an expansive component. Additionally, we have measured the responses of LGN neurons to m-sequence white noise and examined the static relationship between a linear prediction and actual spike rate. We find that this static relationship is well fit by an expansive nonlinear power law with average exponent of 1.58. These results demonstrate that neurons in early visual pathways exhibit expansive nonlinear responses at low contrasts. Although this thalamic expansive nonlinearity has been largely ignored in models of early visual processing, it may have important consequences because it potentially affects the interpretation of a variety of visual functions.
Characterization of Proteins Belonging to the CHAP-Related Superfamily within the Firmicutes
Authors: Layec Séverine , Decaris Bernard , Leblond-Bourget Nathalie
Published: October 2007

Cell division is a dynamic process ending by separation of the daughter cells. This final step requires the cleavage of the murein septum synthetized during cell division. In Streptococcus thermophilus, cse plays an important role in cell separation. Cse protein contains, at its N-terminal end, a signal peptide and a putative LysM motif suggesting that it is secreted and able to bind to the cell wall. Furthermore, the C-terminus of Cse carries a putative cysteine, histidine-dependent amidohydrolases/peptidases (CHAP) domain conferring to the protein a potential catalytic activity. To gain insight into the role of Cse in the cell division process, in silico analysis of the Firmicutes proteins displaying CHAP-related domain was undertaken. This work allowed us to distinguish and characterize within the Firmicutes the 2 families of proteins (CHAP and NlpC/p60) belonging to the CHAP superfamily. These 2 families regroup mainly peptidoglycan hydrolases. Data from the literature indicate that NlpC/p60 and CHAP proteins cleave distinct peptidoglycan bonds. Among the enzymes characterized within the Firmicutes, NlpC/p60 proteins are γ-D-glutamate-meso-diaminopimelate muropeptidase. Instead, CHAP enzymes involved in cell separation are N-acetylmuramoyl-L-alanine amidase and CHAP lysins have endopeptidase activity.
Kinetics and Intensity of the Expression of Genes Involved in the Stress Response Tightly Induced by Phenolic Acids in Lactobacillus plantarum
Authors: Licandro-Seraut Hélène , Gury Jérôme , Tran Ngoc Phuong , Barthelmebs Lise , Cavin Jean-François
Published: October 2007

In Lactobacillus plantarum, PadR, the negative transcriptional regulator of padA encoding the phenolic acid decarboxylase, is divergently oriented from padA. Moreover, it forms an operonic structure with usp1, a genewhose products display homology with proteins belonging to the UspA family of universal stress proteins. PadR is inactivated by the addition of p-coumaric, ferulic or caffeic acid to the culture medium. In order to better characterize the stress response of this bacterium to phenolic acids, we report here the kinetics and quantitative expression by qRT-PCR of the 3 genes from the padA locus. The expression of the 3 genes is very low in the non-induced condition, while the addition of 1.2 mMp-coumaric acid induces an increase in the expression of padA, padR and usp1 by factors of 8,000, 37 and 13, respectively. These maximum relative transcript levels are obtained after 5 min of induction at the end of the exponential growth phase, while phenolic acid decarboxylase activity, not detectable before induction, is increased by a factor of 8,000 in 10 min. The apparent half-life of padA mRNA is about 1.4 min. The padA-padR system displays dynamic characteristics that are valuable to the development of tools for gene expression in this bacterium.
Lactococcus lactis, an Efficient Cell Factory for Recombinant Protein Production and Secretion
Authors: Morello E. , Bermúdez-Humarán L.G. , Llull D. , Solé V. , Miraglio N. , Langella P. , Poquet I.
Published: October 2007

The use of Gram-positive bacteria for heterologous protein production proves to be a useful choice due to easy protein secretion and purification. The lactic acid bacterium Lactococcus lactis emerges as an attractive alternative to the Gram-positive model Bacillus subtilis. Here, we review recent work on the expression and secretion systems available for heterologous protein secretion in L. lactis, including promoters, signal peptides and mutant host strains known to overcome some bottlenecks of the process. Among the tools developed in our laboratory, inactivation of HtrA, the unique housekeeping protease at the cell surface, or complementation of the Sec machinery with B. subtilis SecDF accessory protein each result in the increase in heterologous protein yield. Furthermore, our lactococcal expression/secretion system, using both PZnzitR, an expression cassette tightly controlled by environmental zinc, and a consensus signal peptide, SPExp4, allows efficient production and secretion of the staphylococcal nuclease, as evidenced by protein yields (protein amount/biomass) comparable to those obtained using NICE or P170 expression systems under similar laboratory conditions. Finally, the toolbox we are developing should contribute to enlarge the use of L. lactis as a protein cell factory.
Lactobacillus rhamnosus R11 Consumed in a Food Supplement Survived Human Digestive Transit without Modifying Microbiota Equilibrium as Assessed by Real-Time Polymerase Chain Reaction
Authors: Firmesse Olivier , Mogenet Agnès , Bresson Jean-Louis , Corthier Gérard , Furet Jean-Pierre
Published: October 2007

The aim of this study was to evaluate the survival of Lactobacillus rhamnosus R11 and Lactobacillus acidophilus R52 in the human digestive tract and their effects on the microbiota homeostasis. We designed an open human trial including 14 healthy volunteers. A 3-week exclusion period of fermented products was followed by a 12-day consumption period of 4 capsules daily containing 2 × 109L. rhamnosus R11 and 1 × 108L. acidophilus R52, and a 12-day wash-out period. The 2 strains and dominant bacterial groups of the microbiota were quantified by real-time polymerase chain reaction. At the end of the capsule consumption period, high levels of L. rhamnosus R11 were detected in faecal samples from all volunteers, reaching a mean value of 7.1 log10 colony-forming unit (CFU) equivalents/g of stool. L. acidophilus R52 was detected in the stools of only 1 volunteer, reaching a maximum level of 6.1 log10 CFU equivalents/g of stool. Dilution plating enumerations performed in parallel provided less consistent and generally lower levels. No significant effect of capsule consumption was observed on microbiota homeostasis for the dominant faecal populations. Mean values of 8.8, 9.2, 9.9 and 10.6 log10 CFU equivalents/g of stool were obtained for the Clostridium coccoides, Bifidobacterium sp., Bacteroides sp. and Clostridium leptum groups, respectively.
Updating the Importance of Lactic Acid Bacteria in Fish Farming: Natural Occurrence and Probiotic Treatments
Authors: Gatesoupe François-Joël
Published: October 2007

Many recent papers have deepened the state of knowledge about lactic acid bacteria (LAB) in fish gut. In spite of high variability in fish microbiota, LAB are sometimes abundant in the intestine, notably in freshwater fish. Several strains of Streptococcus are pathogenic to fish. Streptococcus iniae and Lactococcus garvieae are major fish pathogens, against which commercial vaccines are available. Fortunately, most LAB are harmless, and some strains have been reported for beneficial effects on fish health. A major step forward in recent years was the converging evidence that LAB can stimulate the immune system in fish. An open question is whether viability can affect immunostimulation. The issue is crucial to commercialize live probiotics rather than inactivated preparations or extracts. There has been a regain of interest in allochthonous strains used as probiotics for terrestrial animals or humans, due to economical and regulatory constraints, but the short survival in sea water may limit application to marine fish. If viability is required, alternative treatments may include the incorporation of prebiotics in feed, and other dietary manipulations that could promote intestinal LAB. Antagonism to pathogens is the other main feature of candidate probiotics, and there are many reports concerning mainly carnobacteria and Enterococcus. Some bacteriocins were characterized which may be of interest not only for aquaculture, but also for food preservation.
Effects of Spironolactone on Corneal Allograft Survival in the Rat
Authors: Otasevic Ljiljana , Gong Nianqiao , Ritter Thomas , Mergler Stefan , Pleyer Uwe
Published: October 2007

Purpose: Spironolactone has recently been shown to have suppressive effects on several immunoactive and proinflammatory cytokines. In this study, we investigated the effects of spironolactone on the prevention of corneal allograft rejection in a MHC class I/II mismatch rat corneal transplant model. Methods: Grafted animals for corneal survival analysis were assigned to receive either spironolactone suspension (orally, 100 mg/kg/day, n = 7), phosphate-buffered saline (PBS, orally, same volume as spironolactone, n = 9) or remained untreated (n = 16). Additional grafted rats treated with spironolactone (n = 6) or PBS (n = 8) were sacrificed on day 12 for quantitative RT-PCR analysis for mechanistic studies. Results: Mean (±SEM) graft survival was significantly prolonged in animals receiving spironolactone (14.9 ± 2.0 days) compared with both PBS-treated (12.3 ± 1.2 days, p = 0.007) and untreated controls (13.0 ± 1.0 days, p = 0.01). We found a decrease in corneal neovascularization in spironolactone-treated rats compared with the PBS-treated group, although the difference was not statistically significant. Spironolactone affected both systemic (down-regulation of CD25+ cells in spleen) and local immune response (up-regulation of IL-10 in cornea). Conclusion: We present initial results demonstrating anti-inflammatory effects of spironolactone.
Proteomic Analysis of the Trabecular Meshwork of Rats in a Steroid-Induced Ocular Hypertension Model: Downregulation of Type I Collagen C-Propeptides
Authors: Shinzato Manabu , Yamashiro Yoshito , Miyara Nariko , Iwamatsu Akihiro , Takeuchi Kouji , Umikawa Masato , Bayarjargal Maitsetseg , Kariya Ken-ichi , Sawaguchi Shoichi
Published: October 2007

Purpose: To investigate global protein expression profiles in the trabecular meshwork (TM) of normal and glucocorticoid-induced ocular hypertensive rat eyes by proteomic analysis, which has not yet been conducted to date. Materials and Methods: A rat ocular hypertension model was produced by topical application of dexamethasone (DEX) for 4 weeks. Age-matched untreated rats served as controls. Intraocular pressure (IOP) was monitored by an electronic tonometer. TM protein expression profiling and protein identification was carried out by a two-dimensional fluorescence differential gel electrophoresis (2-D DIGE) system and matrix-assisted laser desorption/ionization time-of-flight (MALDI-TOF) mass spectrometry, respectively. Results: In DEX-treated rats, average IOP was elevated significantly, as compared with controls. By the DEX treatment, 14 TM protein spots were up- or downregulated consistently in 2-D DIGE analyses. Proteins exhibiting more than 2-fold statistically significant change were identified by MALDI-TOF mass spectrometry. αA-Crystallin and βA3-crystallin were upregulated, while the C-propeptides of type I collagen were downregulated. Conclusion: Relatively short-term glucocorticoid application induced alteration in the expression of a number of proteins, including downregulation of type I collagen C-propeptides. This could reflect impaired collagen turnover in the TM of glucocorticoid-treated eyes.
A Novel Histone Deacetylase Inhibitor Reduces Abdominal Aortic Aneurysm Formation in Angiotensin II-Infused Apolipoprotein E-Deficient Mice
Authors: Vinh Antony , Gaspari Tracey A. , Liu Hong Bin , Dousha Lovisha F. , Widdop Robert E. , Dear Anthony E.
Published: October 2007

Background/Aims: Aberrant expression of components of the matrix metalloproteinase (MMP) enzyme system is implicated in abdominal aortic aneurysm (AAA) formation. We aimed to investigate the influence of a novel histone deacetylase (HDAC) inhibitor (HDACi) metacept-1 (MCT-1), previously documented to reduce MMP expression, on HDAC activity and MMP expression in aortic smooth muscle cells and the in vivo incidence of AAAs. Methods: Western blot and gelatin zymography were used to determine HDAC activity and MMP-2 expression and activity in rat (rVSMCs) and human aortic vascular smooth muscle cells (hVSMCs) in vitro. In vivo AAAs were generated using apolipoprotein E-deficient mice infused with angiotensin (Ang) II. Immunohistochemistry detected MMP-2 and -9 expression in AAA tissue samples. Results: In vitro, MCT-1 inhibited HDAC activity in rVSMCs, and MMP-2 expression and proteolytic activity in hVSMCs.In vivo, Ang II treatment alone exhibited an AAA incidence of 84%. Doxycycline decreased the incidence of AAAs to 50%. Importantly, MCT-1 reduced AAA incidence to approximately 44%. MMP-2 and -9 immunoreactivity was reduced in MCT-1-treated aortic tissue. Conclusion: The novel HDACi MCT-1 inhibits MMP expressionand AAA incidence suggesting this compound may warrant further investigation in the context of AAA biology.
Impaired Vascular Reactivity in Patients with Chronic Kidney Disease
Authors: Tetzner Fabian , Scholze Alexandra , Wittstock Antje , Zidek Walter , Tepel Martin
Published: October 2007

Background: Patients with chronic kidney disease (CKD) show increased cardiovascular morbidity. We hypothesized that vascular properties which can be routinely evaluated noninvasively are related to different stages of CKD and their clinical and biochemical characteristics. Methods: Arterial vascular properties were quantified by the reflective index using digital photoplethysmography in 260 patients with CKD. Patients were grouped according to estimated glomerular filtration rate (eGFR). Additional measurements were performed in 50 healthy control subjects. Results: In patients with CKD stage 1 and 2 (n = 115; age 65 ± 1 years) the reflective index was 30 ± 1%, whereas in patients with CKD stage 3 and 4 (n = 60; age 72 ± 1 years) the reflective index was 36 ± 1%, and in patients with CKD stage 5 (n = 85; age 64 ± 1 years) the reflective index was 36 ± 1% (p < 0.01 by Kruskal-Wallis test) indicating increased arterial stiffness in advanced CKD. Arterial vascular reactivity was significantly impaired in patients with advanced stages of CKD (stage 1 and 2, 78 ± 12%; stage 3 and 4, 32 ± 12%; stage 5, 33 ± 12%; p < 0.01). Univariate analysis showed a significant correlation of the reflective index and eGFR (Pearson r = –0.24; p < 0.0001). Multivariate regression analysis showed an independent association of the reflective index and eGFR (adjusted correlation coefficient, –0.24; p < 0.001). Conclusion: The advanced stages of CKD are associated with increased vascular stiffness and impaired vascular reactivity and these changes are already present in CKD stage 3 and 4.
Lateralization of the Posterior Parietal Cortex for Internal Monitoring of Self- versus Externally Generated Movements
Authors: Ogawa Kenji , Inui Toshio
Published: October 2007

Internal monitoring or state estimation of movements is essential for human motor control to compensate for inherent delays and noise in sensorimotor loops. Two types of internal estimation of movements exist: self-generated movements, and externally generated movements. We used functional magnetic resonance imaging to investigate differences in brain activity for internal monitoring of self- versus externally generated movements during visual occlusion. Participants tracked a sinusoidally moving target with a mouse cursor. On some trials, vision of either target (externally generated) or cursor (self-generated) movement was transiently occluded, during which subjects continued tracking by estimating current position of either the invisible target or cursor on screen. Analysis revealed that both occlusion conditions were associated with increased activity in the presupplementary motor area and decreased activity in the right lateral occipital cortex compared to a control condition with no occlusion. Moreover, the right and left posterior parietal cortex (PPC) showed greater activation during occlusion of target and cursor movements, respectively. This study suggests lateralization of the PPC for internal monitoring of internally versus externally generated movements, fully consistent with previously reported clinical findings.
Challenges in Mesoscale Prediction of a Nocturnal Stratocumulus-Topped Marine Boundary Layer and Implications for Operational Forecasting
Authors: Vellore Ramesh , Koračin Darko , Wetzel Melanie , Chai Steven , Wang Qing
Published: October 2007

A numerical study using the fifth-generation Pennsylvania State University–National Center for Atmospheric Research Mesoscale Model (MM5) was performed to assess the impact of initial and boundary conditions, the parameterization of turbulence transfer and its coupling with cloud-driven radiation, and cloud microphysical processes on the accuracy of mesoscale predictions and forecasts of the cloud-capped marine boundary layer. Aircraft, buoy, and satellite data and the large eddy simulation (LES) results during the Dynamics and Chemistry of Marine Stratocumulus field experiment (DYCOMS II) in July 2001 were used in the assessment. Three of the tested input fields (Eta, NCEP, and ECMWF) show deficiencies, mainly in the thermodynamic structure of the lowest 1500 m of the marine atmosphere. On a positive note, the simulated marine-layer depth showed good agreement with aircraft observations using the Eta fields, while using the NCEP and ECMWF datasets underestimated the marine-layer depth by about 20%–30%. The predicted turbulence kinetic energy (inversion strength) was about 50% of that obtained from the LES results (aircraft observed). As a consequence of moisture overprediction, the predicted liquid water path was twice the observed by 1–2 g kg−1. The sensitivity tests have shown that the selections of turbulence and cloud microphysical schemes significantly influence the turbulence estimates and cloud parameters. Two of the tested turbulence schemes (Eta PBL and Burk–Thompson) did not exhibit the coupling with radiation. The significant differences in the simulated turbulence estimates appear to be a consequence of the use of water-conserving potential temperature variables. The microphysical parameterization, which uses the number concentration of cloud drops in the autoconversion process, simulates a realistic evolution of precipitable hydrometeors in the cloudy marine layer on the positive side, but on the other hand enhances the decoupling in the turbulence structure. This study can provide guidance to operational forecasters concerning accuracy issues of the commonly used large-scale analyses for model initialization, and optimal selection of model parameterizations in order to simulate and forecast the cloudy atmospheric boundary layer over the ocean.
Statistics of Heavy Rainfall Occurrences in Taiwan
Authors: Chen Ching-Sen , Chen Yi-Leng , Liu Che-Ling , Lin Pay-Liam , Chen Wan-Chin
Published: October 2007

The seasonal variations of heavy rainfall days over Taiwan are analyzed using 6-yr (1997–2002) hourly rainfall data from about 360 rainfall stations, including high-spatial-resolution Automatic Rainfall and Meteorological Telemetry System stations and 25 conventional stations. The seasonal variations and spatial variations of nontyphoon and typhoon heavy rainfall occurrences (i.e., the number of rainfall stations with rainfall rate >15 mm h−1 and daily accumulation >50 mm) are also analyzed. From mid-May to early October, with abundant moisture, potential instability, and the presence of mountainous terrain, nontyphoon heavy rainfall days are frequent (>60%), but only a few stations recorded extremely heavy rainfall (>130 mm day−1) during the passage of synoptic disturbances or the drifting of mesoscale convective systems inland. During the mei-yu season, especially in early June, these events are more widespread than in other seasons. The orographic effects are important in determining the spatial distribution of heavy rainfall occurrences with a pronounced afternoon maximum, especially during the summer months under the southwesterly monsoon flow. After the summer–autumn transition, heavy rainfall days are most frequent over northeastern Taiwan under the northeasterly monsoon flow. Extremely heavy rainfall events (>130 mm day−1) are infrequent during the winter months because of stable atmospheric stratification with a low moisture content. Typhoon heavy rainfall events start in early May and become more frequent in late summer and early autumn. During the analysis period, heavy rainfall occurrences are widespread and dominated by extremely heavy rainfall events (>130 mm day−1) on the windward slopes of the storm circulations. The spatial distribution of typhoon heavy rainfall occurrences depends on the typhoon track with very little diurnal variation.
Airborne Volcanic Ash Forecast Area Reliability
Authors: Stunder Barbara J. B. , Heffter Jerome L. , Draxler Roland R.
Published: October 2007

In support of aircraft flight safety operations, daily comparisons between modeled, hypothetical, volcanic ash plumes calculated with meteorological forecasts and analyses were made over a 1.5-yr period. The Hybrid Single-Particle Lagrangian Integrated Trajectory (HYSPLIT) model simulated the ash transport and dispersion. Ash forecasts and analyses from seven volcanoes were studied. The volcanoes were chosen because of recent eruptions or because their airborne ash could impinge on well-traveled commercial aircraft flight paths. For each forecast–analysis pair, a statistic representing the degree of overlap, the threat score (TS), was calculated. A forecast was classified as acceptable if the TS was greater than 0.25. Each forecast was also categorized by two parameters: the forecast area quadrant with respect to the volcano and a factor related to the complexity of the meteorology. The forecast complexity factor was based on the degree of spread using NCEP ensemble output or using a HYSPLIT offset configuration. In general, the larger the spread of the ensemble or offset forecasts, the greater the complexity. The forecasts were sorted by complexity factor, and then classified by the quartile of the complexity. The volcanic ash forecast area reliability (VAFAR) was calculated for each forecast area quadrant and for each quartile of the complexity factor. VAFAR is the ratio of the number of acceptable forecasts to the total number of forecasts. Most VAFAR values were above 70%. VAFAR values for two of the seven volcanoes (Popocatepetl in Mexico and Tungurahua in Ecuador) tended to be lower than the others. In general, VAFAR decreased with increasing complexity of the meteorology. It should be noted that the VAFAR values reflect the reliability of the meteorological forecasts when compared to the same calculation using analysis data; the dispersion model itself was not evaluated.