bluuebunny/crossref_metadata_2025 huggingface dataset:
Multiple Contributions of Peroxisomal Metabolic Function to Fungal Pathogenicity in
Colletotrichum lagenarium
Authors: Asakura Makoto , Okuno Tetsuro , Takano Yoshitaka
Published: September 2006

In
Colletotrichum lagenarium
, which is the causal agent of cucumber anthracnose,
PEX6
is required for peroxisome biogenesis and appressorium-mediated infection. To verify the roles of peroxisome-associated metabolism in fungal pathogenicity, we isolated and functionally characterized
ICL1
of
C. lagenarium
, which encodes isocitrate lyase involved in the glyoxylate cycle in peroxisomes. The
icl1
mutants failed to utilize fatty acids and acetate for growth. Although Icl1 has no typical peroxisomal targeting signals, expression analysis of the GFP-Icl1 fusion protein indicated that Icl1 localizes in peroxisomes. These results indicate that the glyoxylate cycle that occurs inside the peroxisome is required for fatty acid and acetate metabolism for growth. Importantly, in contrast with the
pex6
mutants that form nonmelanized appressoria, the
icl1
mutants formed appressoria that were highly pigmented with melanin, suggesting that the glyoxylate cycle is not essential for melanin biosynthesis in appressoria. However, the
icl1
mutants exhibited a severe reduction in virulence. Appressoria of the
icl1
mutants failed to develop penetration hyphae in the host plant, suggesting that
ICL1
is involved in host invasion. The addition of glucose partially restored virulence of the
icl1
mutant. Heat shock treatment of the host plant also enabled the
icl1
mutants to develop lesions, implying that the infection defect of the
icl1
mutant is associated with plant defense. Together with the requirement of
PEX6
for appressorial melanization, our findings suggest that peroxisomal metabolic pathways play functional roles in appressorial melanization and subsequent host invasion steps, and the latter step requires the glyoxylate cycle.
Comparison of Two Fingerprinting Techniques, Terminal Restriction Fragment Length Polymorphism and Automated Ribosomal Intergenic Spacer Analysis, for Determination of Bacterial Diversity in Aquatic Environments
Authors: Danovaro R. , Luna G. M. , Dell'Anno A. , Pietrangeli B.
Published: September 2006

We investigated bacterial diversity in different aquatic environments (including marine and lagoon sediments, coastal seawater, and groundwater), and we compared two fingerprinting techniques (terminal restriction fragment length polymorphism [T-RFLP] and automated ribosomal intergenic spacer analysis [ARISA]) which are currently utilized for estimating richness and community composition. Bacterial diversity ranged from 27 to 99 phylotypes (on average, 56) using the T-RFLP approach and from 62 to 101 genotypes (on average, 81) when the same samples were analyzed using ARISA. The total diversity encountered in all matrices analyzed was 144 phylotypes for T-RFLP and 200 genotypes for ARISA. Although the two techniques provided similar results in the analysis of community structure, bacterial richness and diversity estimates were significantly higher using ARISA. These findings suggest that ARISA is more effective than T-RFLP in detecting the presence of bacterial taxa accounting for <5% of total amplified product. ARISA enabled also distinction among aquatic bacterial isolates of
Pseudomonas
spp. which were indistinguishable using T-RFLP analysis. Overall, the results of this study show that ARISA is more accurate than T-RFLP analysis on the 16S rRNA gene for estimating the biodiversity of aquatic bacterial assemblages.
Lack of Evidence for Vertical Transmission of
Campylobacter
spp. in Chickens
Authors: Callicott Kenneth A. , Friðriksdóttir Vala , Reiersen Jarle , Lowman Ruff , Bisaillon Jean-Robert , Gunnarsson Eggert , Berndtson Eva , Hiett Kelli L. , Needleman David S. , Stern Norman J.
Published: September 2006

Campylobacter jejuni
is a major cause of bacterial food-borne infection in the industrial world. There is evidence that
C. jejuni
is present in eggs and hatchery fluff, opening the possibility for vertical transmission from hens to progeny. Poultry operations in Iceland provide an excellent opportunity to study this possibility, since breeding flocks are established solely from eggs imported from grandparent flocks in Sweden. This leaves limited opportunity for grandparents and their progeny to share isolates through horizontal transmission. While
Campylobacter
was not detected in all grandparent flocks, 13 of the 16 egg import lots consisted of eggs gathered from one or more
Campylobacter
-positive grandparent flocks. No evidence of
Campylobacter
was found by PCR in any of the 10 relevant quarantine hatchery fluff samples examined, and no
Campylobacter
was isolated from the parent birds through 8 weeks, while they were still in quarantine rearing facilities. After the birds were moved to less biosecure rearing facilities,
Campylobacter
was isolated, and 29 alleles were observed among the 224 isolates studied. While three alleles were found in both Sweden and Iceland, in no case was the same allele found both in a particular grandparent flock and in its progeny. We could find no evidence for vertical transmission of
Campylobacter
to the approximately 60,000 progeny parent breeders that were hatched from eggs coming from
Campylobacter
-positive grandparent flocks. If vertical transmission is occurring, it is not a significant source for the contamination of chicken flocks with
Campylobacter
spp.
Metabolic-State-Dependent Remodeling of the Transcriptome in Response to Anoxia and Subsequent Reoxygenation in
Saccharomyces cerevisiae
Authors: Lai Liang-Chuan , Kosorukoff Alexander L. , Burke Patricia V. , Kwast Kurt E.
Published: September 2006

We conducted a comprehensive genomic analysis of the temporal response of yeast to anaerobiosis (six generations) and subsequent aerobic recovery (≈2 generations) to reveal metabolic-state (galactose versus glucose)-dependent differences in gene network activity and function. Analysis of variance showed that far fewer genes responded (raw
P
value of ≤10
−8
) to the O
2
shifts in glucose (1,603 genes) than in galactose (2,388 genes). Gene network analysis reveals that this difference is due largely to the failure of “stress”-activated networks controlled by Msn2/4, Fhl1, MCB, SCB, PAC, and RRPE to transiently respond to the shift to anaerobiosis in glucose as they did in galactose. After ≈1 generation of anaerobiosis, the response was similar in both media, beginning with the deactivation of Hap1 and Hap2/3/4/5 networks involved in mitochondrial functions and the concomitant derepression of Rox1-regulated networks for carbohydrate catabolism and redox regulation and ending (≥2 generations) with the activation of Upc2- and Mot3-regulated networks involved in sterol and cell wall homeostasis. The response to reoxygenation was rapid (<5 min) and similar in both media, dominated by Yap1 networks involved in oxidative stress/redox regulation and the concomitant activation of heme-regulated ones. Our analyses revealed extensive networks of genes subject to combinatorial regulation by both heme-dependent (e.g., Hap1, Hap2/3/4/5, Rox1, Mot3, and Upc2) and heme-independent (e.g., Yap1, Skn7, and Puf3) factors under these conditions. We also uncover novel functions for several
cis
-regulatory sites and
trans
-acting factors and define functional regulons involved in the physiological acclimatization to changes in oxygen availability.
A Eukaryote without Catalase-Containing Microbodies:
Neurosporacrassa
Exhibits a Unique Cellular Distributionof Its Four Catalases
Authors: Schliebs Wolfgang , Würtz Christian , Kunau Wolf-Hubert , Veenhuis Marten , Rottensteiner Hanspeter
Published: September 2006

Microbodies usually house catalase to decompose hydrogen peroxide generated within
the organelle by the action of various oxidases. Here we have analyzed
whether peroxisomes (i.e., catalase-containing microbodies) exist in
Neurospora crassa
. Three distinct catalase isoforms were
identified by native catalase activity gels under various
peroxisome-inducing conditions. Subcellular fractionation by density
gradient centrifugation revealed that most of the
spectrophotometrically measured activity was present in the light upper
fractions, with an additional small peak coinciding with the peak
fractions of HEX-1, the marker protein for Woronin bodies, a
compartment related to the microbody family. However, neither in-gel
assays nor monospecific antibodies generated against the three purified
catalases detected the enzymes in any dense organellar fraction.
Furthermore, staining of an
N. crassa
wild-type strain with
3,3′-diaminobenzidine and H
2
O
2
did not
lead to catalase-dependent reaction products within microbodies.
Nonetheless,
N. crassa
does possess a gene (
cat-4
)
whose product is most similar to the peroxisomal type of monofunctional
catalases. This novel protein indeed exhibited catalase activity, but
was not localized to microbodies either. We conclude that
N.
crassa
lacks catalase-containing peroxisomes, a characteristic
that is probably restricted to a few filamentous fungi that produce
little hydrogen peroxide within
microbodies.
The Predicted G-Protein-Coupled Receptor GPR-1 Is Required for Female Sexual Development inthe Multicellular Fungus
Neurospora crassa
Authors: Krystofova Svetlana , Borkovich Katherine A.
Published: September 2006

G-protein-coupled receptors (GPCRs) control important aspects of asexual and sexual
development in eukaryotic organisms. We have identified a predicted
GPCR in the filamentous fungus
Neurospora crassa
with
similarity to cyclic AMP-receptor like GPCRs from
Dictyostelium
discoideum
and GCR1 from
Arabidopsis thaliana
. Expression
of
gpr-1
is highest in female reproductive structures, and
deletion of
gpr-1
leads to defects during sexual development.
Unfertilized female structures (protoperithecia) fromΔ
gpr-1
strains are weakly pigmented, small, and
submerged in the agar. The perithecia produced after fertilization have
deformed beaks that lack ostioles, the openings through which
ascospores are discharged. Localization studies using a GPR-1-green
fluorescent protein fusion protein showed that GPR-1 is targeted to
female reproductive structures. Genetic epistasis experiments with the
three Gα genes were inconclusive due to the early block in
mating exhibited by Δ
gna-1
strains. Phenotypic
analysis of mutants from a high-throughput
N. crassa
knockout
project allowed identification of BEK-1, a homeodomain transcription
factor that is a potential target of GPR-1. The perithecial defects ofΔ
bek-1
strains are similar to those of theΔ
gpr-1
strain, and epistasis analysis indicates that
bek-1
could function downstream of
gpr-1
during
postfertilization events. The effect must be posttranscriptional, as
bek-1
transcript levels are not affected inΔ
gpr-1
strains. The lack of ostioles inΔ
gpr-1
and Δ
bek-1
mutants has an
undesirable effect on the ability to spread progeny (ascospores) by the
normal ejection mechanism and would severely compromise the fitness of
these strains in
nature.
ADVANCEMENTS IN NANOELECTRONIC SONOS NONVOLATILE SEMICONDUCTOR MEMORY (NVSM) DEVICES AND TECHNOLOGY
Authors: White Marvin H. , Wang Yu (Richard) , Wrazien Stephen J. , Zhao Yijie (Sandy)
Published: September 2006

This paper describes the recent advancements in the development of nanoelectronic SONOS nonvolatile semiconductor memory (NVSM) devices and technology, which are employed in both embedded applications, such as microcontrollers, and 'stand-alone', high-density, memory applications, such as cell phones and memory 'sticks'. Multi-dielectric devices, such as the MNOS devices, were among the first NVSM; however, over the ensuing years the double polysilicon, floating-gate device has become the dominant semiconductor NVSM technology. Today, however, questions arise as to future scaling and cost effectiveness of floating gate technology – questions, which have sparked renewed interest in SONOS technology. The latter offers a single polysilicon device structure with reduced lithography steps together with compact cell layouts - compatible with 'standard' CMOS technology for cost effectiveness. In addition, SONOS technology offers performance features, such as reduced erase and write voltage levels to ease the design of peripheral memory circuits with a decrease in electric fields and localized charge storage for improved reliability and multi-bit storage, and ease of memory testing. A special feature of SONOS technology is radiation hardness, which makes this technology ideal for advanced Space and Military systems. SONOS devices use ultra-thin tunnel oxides (2nm) and operate with 'modified' Fowler-Nordheim and 'direct' tunneling in both erase and write (program) modes. A thicker tunnel oxide SONOS device (5nm), called the NROM™ device, uses 'hot electron injection for programming and 'hot hole band-to-band tunneling' for erase. The NROM™ device provides spatially isolated, two-bit storage with the possibility of multi-level charge (MLC) storage at each bit location. This paper describes the physical electronics for these device structures and their erase/write, retention and endurance characteristics. In addition, several novel SONOS device structures are discussed as potential candidates for future NVSM.
TUNABLE COHERENT RADIATION FROM TERAHERTZ TO MICROWAVE BY MIXING TWO INFRARED FREQUENCIES IN A 47-MM-LONG GaSe CRYSTAL
Authors: SHI WEI , DING YUJIE J.
Published: September 2006

By mixing two infrared radiations near 1 μm in a 47-mm-long GaSe crystal, we efficiently generated a monochromatic radiation which has frequency tunability from 4.51 THz down to 53 GHz. The highest peak power produced by us is 389 W at 203 μm (1.48 THz), which corresponds to the photon conversion efficiency of 19% (the power conversion efficiency of 0.098%).
FOCAL REGION-BASED VOLUME RENDERING
Authors: ZHOU JIANLONG , WANG ZHIYAN , TÖNNIES KLAUS D.
Published: September 2006

In this paper, a new approach named focal region-based volume rendering for visualizing internal structures of volumetric data is presented. This approach presents volumetric information through integrating context information as the structure analysis of the data set with a lens-like focal region rendering to show more detailed information. This feature-based approach contains three main components: (i) A feature extraction model using 3D image processing techniques to explore the structure of objects to provide contextual information; (ii) An efficient ray-bounded volume ray casting rendering to provide the detailed information of the volume of interest in the focal region; (iii) The tools used to manipulate focal regions to make this approach more flexible. The approach provides a powerful framework for producing detailed information from volumetric data. Providing contextual information and focal region renditions at the same time has the advantages of easy to understand and comprehend volume information for the scientist. The interaction techniques provided in this approach make the focal region-based volume rendering more flexible and easy to use.
ALLEE EFFECT IN POPULATION DYNAMICS: EXISTENCE OF BREATHER-LIKE BEHAVIOR AND CONTROL OF CHAOS THROUGH DISPERSAL
Authors: HADJIAVGOUSTI DESPINA , ICHTIAROGLOU SIMOS
Published: September 2006

We consider a one-dimensional chain of identical sites, appropriate for colonization by a biological species. The dynamics at each site is subjected to the demographic Allee effect. We consider nonzero probability p of dispersal to the nearby sites and we prove, for small values of p, the existence of asymptotically stable time-periodic and space-localized solutions, such that the central site carries the vast majority of the metapopulation, while the populations at nearby sites attain very small values. We study numerically a chain of three sites, both for the case of open ends or periodic boundary conditions. We study the bifurcations leading to transition from chaotic to periodic behavior and vice-versa and note that the increase of the dispersal probability in both cases controls the chaotic behavior of the metapopulation.
IMAGE COMPRESSION USING RECURRENT BIVARIATE FRACTAL INTERPOLATION SURFACES
Authors: BOUBOULIS P. , DALLA LEONI , DRAKOPOULOS V.
Published: September 2006

A new method for constructing recurrent bivariate fractal interpolation surfaces through points sampled on rectangular lattices is proposed. This offers the advantage of a more flexible fractal modeling compared to previous fractal techniques that used affine transformations. The compression ratio for the above mentioned fractal scheme as applied to real images is higher than other fractal methods or JPEG, though not as high as JPEG2000. Theory, implementation and analytical study are also presented.
QUALITY AND PERFORMANCE RELIABILITY ASSESSMENT OF MULTI-RESPONSE DEGRADING SYSTEMS
Authors: SON YOUNG KAP , SAVAGE GORDON J.
Published: September 2006

This paper presents a non-sampling based method for the simultaneous evaluation of quality and performance reliability of engineering systems with multiple time-variant responses due to multiple degrading components. This work provides a platform for robust design of degrading systems. The system performance degradations are related to component degradations using mechanistic models. The system soft failure is defined as the non-conformance of any response with respect to critical levels and such relations are easily modeled as time dependent limit-state functions. Then, for discrete time it is shown that an incremental failure set that emerges from a safe region can be written using only a pair of successive system instantaneous failure sets. The cumulative distribution function of soft failure is built by summing the incremental failure probabilities. A practical implementation of the proposed method can be manifest by first-order reliability methods (FORM) and second-order bounds. The proposed method can be used to assess initial quality and performance reliability of systems with combinations of designated means and tolerances. Examples of electro mechanical systems show the details of the formulation and the potential of the approach. Error sources and their magnitudes are discussed.
A DP-BASED CHECKPOINTING SCHEME IN REAL-TIME APPLICATIONS
Authors: OKAMURA HIROYUKI , IWAMOTO KAZUKI , DOHI TADASHI
Published: September 2006

In this paper, we consider computation algorithms for checkpoint placement in real-time applications. Under the condition that the processing time is bounded by a time limit, we derive sequentially the optimal checkpoint time based on the dynamic programming. In numerical examples, we examine the dependence of optimal checkpoint sequence on both failure time and processing time distributions, and investigate the effectiveness of sequential checkpoint placement.
RECURSIVE METHOD FOR RELIABILITY EVALUATION OF CIRCULAR CONSECUTIVE 2-OUT-OF-(r,r)-FROM-(n,n):F SYSTEMS
Authors: HIGASHIYAMA YOICHI , OHKURA TATSUNARI , RUMCHEV VENTSI G.
Published: September 2006

This paper proposes a new reliability model, circular consecutive 2-out-of-(r,r)-from-(n,n): F model. In this model, the system consists of a square grid of side n (containing of n2 components) such that the system fails if and only if there is at least one square of side r which includes among them at least two failed components. For i.i.d. case an algorithm is given for computing the reliability of circular system. The reliability function can be expressed by the number of 0–1 matrices having no two or more 0s at any square of side r.
PARTICLE STATISTICS IN ALUMINUM ALLOYS
Authors: HARLOW D. GARY
Published: September 2006

Pitting corrosion and fatigue crack growth are primary degradation mechanisms that affect the durability and integrity of structures made of aluminum alloys, and they are concerns for commercial transport and military aircraft. The heterogeneous nature of aluminum alloys is the reason that these are operative damage mechanisms. Typically, there are about 2,000 constituent particles per mm2on polished surfaces. Corrosion pits commence at the constituent particles and evolve into severe pits by sustained growth through clusters of particles. The severe pits are nucleation sites for subsequent fatigue crack growth. Even when the environment is not as deleterious, fatigue cracks nucleate from clusters of particles. Thus, the role of heterogeneous clusters of constituent particles is critical to the damage evolution of aluminum alloys. To formulate stochastic models that can serve as part of structural reliability analyses for the damage evolution in aluminum alloys, it is essential that quantitative descriptions of the spatial statistics of the particles and particle clusters, including their location, size, and density are developed. The primary purpose of this effort is to estimate statistically the distribution functions of the key geometrical properties of constituent particles in aluminum alloys and their role in damage evolution.
Increased postprandial responses of GLP-1 and GIP in patients with chronic pancreatitis and steatorrhea following pancreatic enzyme substitution
Authors: Knop Filip K. , Vilsbøll Tina , Larsen Steen , Højberg Patricia V. , Vølund Aage , Madsbad Sten , Holst Jens J. , Krarup Thure
Published: September 2006

We aimed to investigate how assimilation of nutrients affects the postprandial responses of glucagon-like peptide-1 (GLP-1) and glucose-dependent insulinotropic polypeptide (GIP) and to evaluate the effect of pancreatic enzyme substitution (PES) on insulin secretion in patients with chronic pancreatitis (CP) and pancreatic exocrine insufficiency (PEI). Eight male patients with CP and PEI were studied. Blood was sampled frequently on two separate days after ingestion of a liquid meal with and without PES, respectively. Eight healthy male subjects served as a control group. β-Cell responsiveness was estimated as changes in insulin secretion rates in response to changes in postprandial plasma glucose (PG). There was no difference in the PG incremental area under curve (AUC) for patients with and without PES [406 ± 100 vs. 425 ± 80 mM·4 h (mean ± SE), P = 0.8]. The response of total GLP-1 was higher after PES (AUC: 7.8 ± 1.2 vs. 5.3 ± 0.6 nM·4 h, P = 0.01), as was the response of total GIP (AUC: 32.7 ± 7.5 vs. 21.1 ± 8.3 nM·4 h, P = 0.01). Concurrently, both plasma insulin, plasma C-peptide, and total insulin secretion increased after PES (AUC: 17.7 ± 4.2 vs. 13.6 ± 2.9 nM·4 h, P = 0.02; 237 ± 31.4 vs. 200 ± 27.4 nM·4 h, P = 0.005; and 595 ± 82 vs. 497 ± 80 pmol·kg−1·4 h, P = 0.01, respectively). β-Cell responsiveness to glucose was not significantly different on the two study days for patients with CP. These results suggest that the secretion of GLP-1 and GIP is under influence of the digestion and absorption of nutrients in the small intestine and that PES increases insulin secretion.
Na-K-ATPase regulates tight junction permeability through occludin phosphorylation in pancreatic epithelial cells
Authors: Rajasekaran Sigrid A. , Barwe Sonali P. , Gopal Jegan , Ryazantsev Sergey , Schneeberger Eveline E. , Rajasekaran Ayyappan K.
Published: September 2006

Tight junctions are crucial for maintaining the polarity and vectorial transport functions of epithelial cells. We and others have shown that Na-K-ATPase plays a key role in the organization and permeability of tight junctions in mammalian cells and analogous septate junctions in Drosophila. However, the mechanism by which Na-K-ATPase modulates tight junctions is not known. In this study, using a well-differentiated human pancreatic epithelial cell line HPAF-II, we demonstrate that Na-K-ATPase is present at the apical junctions and forms a complex with protein phosphatase-2A, a protein known to be present at tight junctions. Inhibition of Na-K-ATPase ion transport function reduced protein phosphatase-2A activity, hyperphosphorylated occludin, induced rearrangement of tight junction strands, and increased permeability of tight junctions to ionic and nonionic solutes. These data suggest that Na-K-ATPase is required for controlling the tight junction gate function.
Altered high-energy phosphate metabolism predicts contractile dysfunction and subsequent ventricular remodeling in pressure-overload hypertrophy mice
Authors: Maslov M. Y. , Chacko V. P. , Stuber M. , Moens A. L. , Kass D. A. , Champion H. C. , Weiss R. G.
Published: September 2006

To study the role of early energetic abnormalities in the subsequent development of heart failure, we performed serial in vivo combined magnetic resonance imaging (MRI) and 31P magnetic resonance spectroscopy (MRS) studies in mice that underwent pressure-overload following transverse aorta constriction (TAC). After 3 wk of TAC, a significant increase in left ventricular (LV) mass (74 ± 4 vs. 140 ± 26 mg, control vs. TAC, respectively; P < 0.000005), size [end-diastolic volume (EDV): 48 ± 3 vs. 61 ± 8 μl; P < 0.005], and contractile dysfunction [ejection fraction (EF): 62 ± 4 vs. 38 ± 10%; P < 0.000005] was observed, as well as depressed cardiac energetics (PCr/ATP: 2.0 ± 0.1 vs. 1.3 ± 0.4, P < 0.0005) measured by combined MRI/MRS. After an additional 3 wk, LV mass (140 ± 26 vs. 167 ± 36 mg; P < 0.01) and cavity size (EDV: 61 ± 8 vs. 76 ± 8 μl; P < 0.001) increased further, but there was no additional decline in PCr/ATP or EF. Cardiac PCr/ATP correlated inversely with end-systolic volume and directly with EF at 6 wk but not at 3 wk, suggesting a role of sustained energetic abnormalities in evolving chamber dysfunction and remodeling. Indeed, reduced cardiac PCr/ATP observed at 3 wk strongly correlated with changes in EDV that developed over the ensuing 3 wk. These data suggest that abnormal energetics due to pressure overload predict subsequent LV remodeling and dysfunction.
Ghrelin improves burn-induced delayed gastrointestinal transit in rats
Authors: Sallam H. S. , Oliveira H. M. , Gan H. T. , Herndon D. N. , Chen J. D. Z.
Published: September 2006

Delayed gastrointestinal transit is common in patients with severe burn. Ghrelin is a potent prokinetic peptide. We aimed at testing the effect of ghrelin on burn-induced delayed gastrointestinal transit in rats. Gastric emptying (GE), intestinal transit (IT), and colonic transit (CT) studies were performed in male Sprague-Dawley rats. Rats were randomized into two main groups as follows: sham injury and ghrelin-treated burn injury with doses of 0, 2, 5, and 10 nmol/rat ip 6 h after burn. Sham/burn injury was induced under anesthesia. Rats received a phenol red meal 20 min following ghrelin injection. Based on the most effective ghrelin dose, 1 mg/kg sc atropine was given 30 min before the ghrelin in one group of rats for each study. The rats in each group were killed 30–90 min later; their stomachs, intestines, and colons were harvested immediately, and the amount of phenol red recovered was measured. Percentage of gastric emptying (GE%) and geometric center for IT and CT were calculated. We found 1) severe cutaneous burn injury significantly delayed GE, IT, and CT compared with sham injury ( P < 0.05); 2) ghrelin normalized both GE and IT, but not the CT; 3) the most effective dose of ghrelin was 2 nmol/rat; and 4) atropine blocked the prokinetic effects of ghrelin on GE% and IT. In conclusion, ghrelin normalizes burn-induced delayed GE and IT but has no effect on CT in rats. The prokinetic effects of ghrelin are exerted via the cholinergic pathway. Ghrelin may have a therapeutic potential for burn patients with delayed upper gastrointestinal transit.
Modulation of membrane potential by an acetylcholine-activated potassium current in trout atrial myocytes
Authors: Molina Cristina E. , Gesser Hans , Llach Anna , Tort Lluis , Hove-Madsen Leif
Published: September 2006

Application of the current-clamp technique in rainbow trout atrial myocytes has yielded resting membrane potentials that are incompatible with normal atrial function. To investigate this paradox, we recorded the whole membrane current ( Im) and compared membrane potentials recorded in isolated cardiac myocytes and multicellular preparations. Atrial tissue and ventricular myocytes had stable resting potentials of −87 ± 2 mV and −83.9 ± 0.4 mV, respectively. In contrast, 50 out of 59 atrial myocytes had unstable depolarized membrane potentials that were sensitive to the holding current. We hypothesized that this is at least partly due to a small slope conductance of Imaround the resting membrane potential in atrial myocytes. In accordance with this hypothesis, the slope conductance of Imwas about sevenfold smaller in atrial than in ventricular myocytes. Interestingly, ACh increased Imat −120 mV from 4.3 pA/pF to 27 pA/pF with an EC50of 45 nM in atrial myocytes. Moreover, 3 nM ACh increased the slope conductance of Imfourfold, shifted its reversal potential from −78 ± 3 to −84 ± 3 mV, and stabilized the resting membrane potential at −92 ± 4 mV. ACh also shortened the action potential in both atrial myocytes and tissue, and this effect was antagonized by atropine. When applied alone, atropine prolonged the action potential in atrial tissue but had no effect on membrane potential, action potential, or Imin isolated atrial myocytes. This suggests that ACh-mediated activation of an inwardly rectifying K+current can modulate the membrane potential in the trout atrial myocytes and stabilize the resting membrane potential.
Soluble betaglycan reduces renal damage progression indb/dbmice
Authors: Juárez Patricia , Vilchis-Landeros M. Magdalena , Ponce-Coria José , Mendoza Valentín , Hernández-Pando Rogelio , Bobadilla Norma A. , López-Casillas Fernando
Published: September 2006

Transforming growth factor-β (TGF-β) is a key mediator in the pathogenesis of renal diseases. Betaglycan, also known as the type III TGF-β receptor, regulates TGF-β action by modulating its access to the type I and II receptors. Betaglycan potentiates TGF-β; however, soluble betaglycan, which is produced by the shedding of the membrane-bound receptor, is a potent antagonist of TGF-β. In the present work, we have used a recombinant form of soluble betaglycan (SBG) to prevent renal damage in genetically obese and diabetic db/db mice. Eight-wk-old db/db or nondiabetic ( db/m) mice were injected intraperitoneally with 50 μg of SBG or vehicle alone three times a wk for 8 wk. The db/db mice that received vehicle presented albuminuria and increased serum creatinine, as well as glomerular mesangial matrix expansion. The db/db mice treated with SBG exhibited a reduction in serum creatinine, albuminuria, and structural renal damage. These effects were associated with lower kidney levels of mRNAs encoding TGF-β1, TGF-β2, TGF-β3, collagen IV, collagen I, fibronectin, and serum glucocorticoid kinase as well as a reduction in the immunostaining of collagen IV and fibronectin. Our data indicate that SBG is a renoprotective agent that neutralized TGF-β actions in this model of nephropathy. Because SBG has a high affinity for all TGF-β isoforms, in particular TGF-β2, it is found naturally in serum and tissues and its shedding may be regulated. We believe that SBG shall prove convenient for long-term treatment of kidney diseases and other pathologies in which TGF-β plays a pathophysiological role.
Gene expression profiling in the neuroendocrine brain of male goldfish (Carassius auratus) exposed to 17α-ethinylestradiol
Authors: Martyniuk Christopher J. , Xiong Huiling , Crump Kate , Chiu Suzanne , Sardana Ravinder , Nadler Ashlie , Gerrie Emily R. , Xia Xuhua , Trudeau Vance L.
Published: September 2006

17-α Ethinylestradiol (EE2), a pharmaceutical estrogen, is detectable in water systems worldwide. Although studies report on the effects of xenoestrogens in tissues such as liver and gonad, few studies to date have investigated the effects of EE2 in the vertebrate brain at a large scale. The purpose of this study was to develop a goldfish brain-enriched cDNA array and use this in conjunction with a mixed tissue carp microarray to study the genomic response to EE2 in the brain. Gonad-intact male goldfish were exposed to nominal concentrations of 0.1 nM (29.6 ng/l) and 1.0 nM (296 ng/l) EE2 for 15 days. Male goldfish treated with the higher dose of EE2 had significantly smaller gonads compared with controls. Males also had a significantly reduced level of circulating testosterone (T) and 17β-estradiol (E2) in both treatment groups. Candidate genes identified by microarray analysis fall into functional categories that include neuropeptides, cell metabolism, and transcription/translation factors. Differentially expressed genes verified by real-time RT-PCR included brain aromatase, secretogranin-III, and interferon-related developmental regulator 1. Our results suggest that the expression of genes in the sexually mature adult brain appears to be resistant to low EE2 exposure but is affected significantly at higher doses of EE2. This study demonstrates that microarray technology is a useful tool to study the effects of endocrine disrupting chemicals on neuroendocrine function and suggest that exposure to EE2 may have significant effects on localized E2 synthesis in the brain by affecting transcription of brain aromatase.
Identification of a human ortholog of the mouseDcppgene locus, encoding a novel member of the CSP-1/Dcpp salivary protein family
Authors: Mullins John J. , Mullins Linda J. , Dunbar Donald R. , Brammar William J. , Gross Kenneth W. , Morley Steven D.
Published: September 2006

Salivary fluid, the collective product of numerous major and minor salivary glands, contains a range of secretory proteins that play key defensive, digestive, and gustatory roles in the oral cavity. To understand the distinct protein “signature” contributed by individual salivary glands to salivary secretions, we studied a family of proteins shown by in vitro mRNA translation to be abundantly expressed in mouse sublingual glands. Molecular cloning, Southern blotting, and restriction fragment length polymorphism analyses showed these to represent one known and two novel members of the common salivary protein (CSP-1)/Demilune cell and parotid protein (Dcpp) salivary protein family, the genes for which are closely linked in the T-complex region of mouse chromosome 17. Bioinformatic analysis identified a putative human CSP-1/Dcpp ortholog, HRPE773, expressed predominantly in human salivary tissue, that shows 31% amino acid identity and 45% amino acid similarity to the mouse Dcpp query sequence. The corresponding human gene displays a similar structure to the mouse Dcpp genes and is located on human chromosome 16 in a region known to be syntenic with the T-complex region of mouse chromosome 17. The predicted mouse and human proteins both display classical NH2-terminal signal sequences, putative jacalin-related lectin domains, and potential N-linked glycosylation sites, suggesting secretion via sublingual saliva into the oral cavity where they may display antimicrobial activity or provide a defensive coating to enamel. Identification of a human CSP-1/Dcpp ortholog therefore provides a key tool for investigation of salivary protein function in human oral health and disease.
Unraveling in vivo Functions of Amyloid Precursor Protein: Insights from Knockout and Knockdown Studies
Authors: Senechal Yann , Larmet Yves , Dev Kumlesh K.
Published: September 2006

The amyloid precursor protein (APP) is a widely expressed transmembrane protein that is cleaved to generate Aβ peptides in the central nervous system and is a key player in the pathogenesis of Alzheimer’s disease. The precise biological functions of APP still remain unclear although various roles have been proposed. While a commonly accepted model argues that Aβ peptides are the cause of onset and early pathogenesis of Alzheimer’s disease, recent discussions challenge this ‘Aβ hypothesis’ and suggest a direct role for APP in this neurodegenerative disease. Loss-of-function studies are an efficient way to elucidate the role of proteins and concurrently a variety of in vitro and in vivo studies has been performed for APP where protein levels have been downregulated and functional consequences monitored. Complete disruption of APP gene expression has been achieved by the generation of APP knockout animal models. Further knockdown studies using antisense and RNA interference have allowed scientists to reduce APP expression levels and have opened new avenues to explore the physiological roles of APP. In the present review, we focus on knockout and knockdown approaches that have provided insights into the physiological functions of APP and discuss their advantages and drawbacks.
The Effect of High Extracellular Potassium on IKr Inhibition by Anti-Arrhythmic Agents
Authors: Lin Congrong , Ke Xiaogang , Cvetanovic Ivana , Ranade Vasant , Somberg John
Published: September 2006

Background: Hyperkalemia is a potentially life-threatening disorder frequently occurring in hospitalized patients. The ischemic myocardium releases potassium into the extracellular space which can cause regional hyperkalemia. These changes may modify the effects of anti-arrhythmic drugs acting on the rapid component of the delayed rectifier potassium current (IKr). We evaluated the influence of increased extracellular potassium concentration [K+]e on IKr inhibition by amiodarone, azimilide, dofetilide, quinidine and sotalol. Methods and Results: Experiments were performed at room temperature. IKr current was studied by using HERG gene expressed in Xenopus oocytes as a model of cardiac IKr. Two-electrode voltage clamp technique was employed. The recording bath solutions contained either 5 or 10 mmol/l KCl. Amiodarone, azimilide, dofetilide, quinidine and sotalol all produced a dose-dependent inhibition of HERG current. At 5 mmol/l [K+]e, the IC50 was 37.0 ± 12.5 µM for amiodarone, 5.8 ± 0.4 µM for azimilide, 1.5 ± 0. 2 µM for dofetilide, 9.1 ± 1.5 µM for quinidine, and 5.1 ± 0.8 mM for sotalol. Raising the extracellular potassium to 10 mmol/l, HERG block by azimilide, dofetilide, quinidine and sotalol was significantly decreased, while the block by amiodarone was unchanged. The differences in the percentage current block produced by 3 µM drugs at 5 and 10 mmol/l [K+]e were: –0.9% for amiodarone, 13.8% for quinidine, 20.5% for azimilide, and 16.2% for dofetilide. The differences in percentage block between 5 and 10 mmol/l [K+]e by sotalol 10 and 30 mM were 7.1 and 5.6%. At 10 mmol/l [K+]e, the IC50 was increased for azimilide, dofetilide, quinidine and sotalol but not for amiodarone; the IC50 was 24.7 ± 7.4 µM for amiodarone, 29.3 ± 3.9 µM for azimilide, 2.7 ± 0.2 µM for dofetilide, 27.6 ± 4.0 µM for quinidine, and 7.2 ± 1.7 mM for sotalol. Conclusion: Inhibition of IKr by azimilide, quinidine, dofetilide and sotalol was diminished by increasing [K+]e, while the inhibition by amiodarone was unchanged at normal and high [K+]e. The differential effects of azimilide, dofetilide, quinidine and sotalol at normal and high [K+]e could be pro-arrhythmic by favoring re-entry arrhythmias. These results further support the unique electrophysiological effect of amiodarone.
Signal Transduction Pathways Mediating CCK-8S-Induced Gastric Antral Smooth Muscle Contraction
Authors: Si Xin-Min , Huang Lei , Paul Shelley Chireyath , An Ping , Luo He-Sheng
Published: September 2006

Aim: To investigate the functional and molecular mechanisms by which sulfated cholecystokinin octapeptide (CCK-8S) regulates calcium mobilization in gastric antral smooth muscle cells (SMCs) of rats. Methods: Isotonic contraction of antral strips was recorded using a polyphysiograph. Immunoprecipitation was used to determine the regulatory effect of protein kinase C (PKC) on regulating the phosphorylation of the type III inositol 1,4,5-triphosphate receptor (InsP3R3) in gastric SMCs. Alterations in the intracellular calcium ([Ca2+]i) concentration were assayed using fura-2/AM-loaded microspectrofluorometry, and the L-type calcium current (ICa-L) was recorded by patch-clamp techniques. Results: CCK-8S (5 × 10–8 mol/l) significantly increased the mean contractile amplitude of circular muscle by 61.85 ± 12.67% and the frequency of longitudinal muscle by 57.91 ± 15.70% in gastric antral strips, which were suppressed by dexloxiglumide or thapsigargin (TG) and BAPTA-AM (BA). Treatment withchelerythrine (5 × 10–8 mmol/l) significantly inhibited the CCK-8S-increased phosphorylation of InsP3R3 in SMCs. The amplitudes of the CCK-8S-triggered [Ca2+]i concentration oscillations were reduced in a dose-dependent manner when the SMCs were pretreated with increasing concentrations of PMA (from 10–8 to 10–5 mol/l). On removal of extracellular calcium or blocking ICa-L by nifedipine, a smaller but significant rise in the [Ca2+]i concentration was still elicited by CCK-8S. When [Ca2+]i was depleted by the administration of 10–5 mol/l TG and 10–5 mol/l BA or blocked by the calcium-dependent chloride current (ICl-Ca) by giving 5 × 10–6 mol/l niflumic acid, the CCK-8S-intensified ICa-L (from –56.42 ± 6.57 to –88.54 ± 5.71 pA) was apparently inhibited by 90.34 ± 4.71% and 82.59 ± 4.24%. Conclusions: These results demonstrate that the CCK-8S-evoked [Ca2+]i concentration increase in gastric antral SMCs depends on the release of [Ca2+]i stores which are negatively regulated by PKC-mediated phosphorylation of InsP3R3. Released calcium in turn activates ICa-L through the activation of ICl-Ca, ultimately resulting in the contraction of the gastric smooth muscle.
Influence of Premorbid IQ and Education on Progression of Alzheimer’s Disease
Authors: Pavlik V.N. , Doody R.S. , Massman P.J. , Chan W.
Published: September 2006

Background: Lower education is associated with a higher risk of developing Alzheimer’s disease (AD). Years of education and measures of general intellectual function (IQ) are highly correlated. It is important to determine whether there is a relationship between education and AD outcomes that is independent of IQ. Objective: To test the hypothesis that premorbid IQ is a stronger predictor of cognitive decline, global progression, and overall survival, than education in patients with AD. Methods: The study included 478 probable AD patients (322 women and 156 men, mean age 74.5 years) followed in a large AD referral center for a mean of 3.2 years. Eligible participants had a baseline estimate of premorbid IQ using the American version of the Nelson Adult Reading Test (AMNART) and at least one follow-up visit with complete neuropsychological assessment. We used random effects linear regression analysis, and Cox proportional hazards analysis to determine whether or not education and/or premorbid IQ were independently associated with cognitive decline, global progression of AD, and survival. Results: When the baseline AMNART score was included in regression models along with education and other demographic variables, AMNART score, but not education, was associated with a higher baseline score and slower rate of decline in MMSE and ADAS-Cog scores, and the Clinical Dementia Rating sum of boxes score. Neither higher premorbid IQ nor higher education was associated with longer survival. Conclusions: We conclude that a baseline AMNART score is a better predictor of cognitive change in AD than education, but neither variable is associated with survival after diagnosis.
The Role of 123I-Metaiodobenzylguanidine Myocardial Scintigraphy in the Diagnosis of Lewy Body Disease in Patients with Dementia in a Memory Clinic
Authors: Hanyu Haruo , Shimizu Soichiro , Hirao Kentaro , Sakurai Hirofumi , Iwamoto Toshihiko , Chikamori Taishiro , Hida Satoshi , Yamashina Akira , Koizumi Kiyoshi , Abe Kimihiko
Published: September 2006

Reduction in cardiac 123I-metaiodobenzylguanidine (MIBG) uptake is a characteristic feature of Parkinson’s disease (PD) and dementia with Lewy bodies (DLB), and is useful in distinguishing them from other neurodegenerative disorders. The aim of this study was to investigate the role of this method of scintigraphy in the differential diagnosis of dementia in our Memory Clinic. We performed MIBG scintigraphy in patients with dementia referred to the Memory Clinic and compared the heart-to-mediastinum (H/M) ratio of MIBG uptake. Thirty out of 32 patients with DLB and all 9 PD with dementia patients had reduced H/M ratios, whereas 37 out of 40 patients with Alzheimer’s disease had normal H/M ratios. Most patients with vascular dementia, frontotemporal dementia, and other dementias had normal H/M ratios. The overall sensitivity to positively identify patients with Lewy body disease (including DLB and PD with dementia) was 95%, and the specificity to distinguish them from patients with other types of dementias was 87%. MIBG scintigraphy showed a high sensitivity for the detection of Lewy body disease, and also a high specificity for discrimination from other types of dementia. The scintigraphy may provide a valuable and adjunctive method in the diagnosis of Lewy body disease and a differential diagnostic tool for patients with dementias.
Exercise Capacity and Pulmonary Function in Hospital Workers Recovered from Severe Acute Respiratory Syndrome
Authors: Su Mao-Chang , Hsieh Yu-Tang , Wang Yi-Hsi , Lin An-Shen , Chung Yu-Hsiu , Lin Meng-Chih
Published: September 2006

Background: Persistent impaired pulmonary function and functional capacity are common among survivors of severe acute respiratory syndrome (SARS). Whether the impairment was caused by SARS or pre-existing physical condition remains unclear. Objective: This study investigated the influence of SARS on exercise capacity and pulmonary function of previously healthy medical staff.Methods: Pulmonary function tests, including spirometry and carbon monoxide diffusing capacity (DLCO), as well as symptom-limited cardiopulmonary exercise testing (CPET) with an incremental protocol using an electronically braked cycle ergometer, were performed by 13 previously healthy hospital workers 14 months after SARS recovery. Other 14 age- and sex-matched healthy medical workers completed CPET simultaneously, and exercise capacities of these two groups were compared. Results: Most values of spirometry performed were within normal range. Only one showed mildly restrictive abnormality with decreased forced expiratory volume in 1 s (72.2% predicted) and forced vital capacity (68.1% predicted). Eight subjects had decreased DLCO levels (mean 79.37 ± 7.73%), and low exercise capacity was noted in 9 subjects. Discordance in impairment of the measured DLCO and exercise capacity was revealed by comparison. Besides, there was no significant difference in results of CPET between subjects recovered from SARS and those never infected. Conclusions: Minor pulmonary function defects as well as decreased exercise capacity were detected in previously healthy medical staff after recovering from SARS. No significant correlation between exercise capacity and pulmonary function was found.