bluuebunny/crossref_metadata_2025 huggingface dataset:
Environmental Temperature Controls
Cryptosporidium
Oocyst Metabolic Rate and Associated Retention of Infectivity
Authors: King Brendon J. , Keegan Alexandra R. , Monis Paul T. , Saint Christopher P.
Published: July 2005

Cryptosporidium
is a significant cause of water-borne enteric disease throughout the world and represents a challenge to the water industry and a threat to public health. In this study we report the use of a cell culture-TaqMan PCR assay to measure oocyst inactivation rates in reagent-grade and environmental waters over a range of temperatures. While oocysts incubated at 4°C and 15°C remained infective over the 12-week holding period, we observed a 4 log
10
reduction in infectivity for both 20 and 25°C incubation treatments at 12 and 8 weeks, respectively, for all water types examined, a faster rate of inactivation for oocysts than previously reported. This temperature-dependent inactivation was further investigated using a simple and rapid ATP assay described herein. Time course experiments performed in reagent-grade water at incubation temperatures of 4, 15, 20, 25, 30, and 37°C identified a close relationship between oocyst infectivity and oocyst ATP content, demonstrating that temperature inactivation at higher temperatures is a function of increased oocyst metabolic activity. While water quality did not affect oocyst inactivation, biological antagonism appears to be a key factor affecting oocyst removal from environmental waters. Both the cell culture-TaqMan PCR assay and the ATP assay provide a sensitive and quantitative method for the determination of environmental oocyst inactivation, providing an alternative to the more costly and time-consuming mouse infection assay. The findings presented here relating temperature to oocyst inactivation provide valuable information for determining the relative risks associated with
Cryptosporidium
oocysts in water.
An Internal Reference Technique for Accurately Quantifying Specific mRNAs by Real-Time PCR with Application to the
tceA
Reductive Dehalogenase Gene
Authors: Johnson David R. , Lee Patrick K. H. , Holmes Victor F. , Alvarez-Cohen Lisa
Published: July 2005

The accuracy of mRNA quantification by reverse transcription (RT) in conjunction with real-time PCR (qPCR) is limited by mRNA losses during sample preparation (cell lysis, RNA isolation, and DNA removal) and by inefficiencies in reverse transcription. To control for these losses and inefficiencies, a technique was developed that utilizes an exogenous internal reference mRNA (
ref
mRNA) along with mRNA absolute standard curves. The technique was applied to quantify mRNA of the trichloroethene (TCE) reductive dehalogenase-encoding
tceA
gene in an anaerobic TCE-to-ethene dechlorinating microbial enrichment. Compared to RT-qPCR protocols that utilize DNA absolute standard curves, application of the new technique increased measured quantities of
tceA
mRNA by threefold, demonstrating a substantial improvement in quantification. The technique was also effective for quantifying the loss of mRNA during specific steps of the sample processing protocol. Analysis revealed that the efficiency of the RNA isolation (56%) step was significantly less than that of the cell lysis (84%), DNA removal (93%), and RT (88%) steps. The technique was applied to compare the effects of cellular exposure to different chlorinated ethenes on
tceA
expression. Results show that exposure to TCE or
cis
-1,2-dichloroethene resulted in 25-fold-higher quantities of
tceA
mRNA than exposure to vinyl chloride or chlorinated ethene starvation.
Effects of Subtherapeutic Administration of Antimicrobial Agents to Beef Cattle on the Prevalence of Antimicrobial Resistance in
Campylobacter jejuni
and
Campylobacter hyointestinalis
Authors: Inglis G. D. , McAllister T. A. , Busz H. W. , Yanke L. J. , Morck D. W. , Olson M. E. , Read R. R.
Published: July 2005

The influence of antimicrobial agents on the development of antimicrobial resistance (AMR) in
Campylobacter
isolates recovered from 300 beef cattle maintained in an experimental feedlot was monitored over a 315-day period (11 sample times). Groups of calves were assigned to one of the following antimicrobial treatments: chlortetracycline and sulfamethazine (CS), chlortetracycline alone (Ct), virginiamycin, monensin, tylosin phosphate, and no antimicrobial agent (i.e., control treatment). In total, 3,283 fecal samples were processed for campylobacters over the course of the experiment. Of the 2,052 bacterial isolates recovered, 92% were
Campylobacter
(1,518 were
Campylobacter hyointestinalis
and 380 were
C. jejuni
). None of the antimicrobial treatments decreased the isolation frequency of
C. jejuni
relative to the control treatment. In contrast,
C. hyointestinalis
was isolated less frequently from animals treated with CS and to a lesser extent from animals treated with Ct. The majority (≥94%) of
C. jejuni
isolates were sensitive to ampicillin, erythromycin, and ciprofloxacin, but more isolates with resistance to tetracycline were recovered from animals fed Ct. All of the 1,500 isolates of
C. hyointestinalis
examined were sensitive to ciprofloxacin. In contrast, 11%, 10%, and 1% of these isolates were resistant to tetracycline, erythromycin, and ampicillin, respectively. The number of animals from which
C. hyointestinalis
isolates with resistance to erythromycin and tetracycline were recovered differed among the antimicrobial treatments. Only Ct administration increased the carriage rates of erythromycin-resistant isolates of
C. hyointestinalis
, and the inclusion of CS in the diet increased the number of animals from which tetracycline-resistant isolates were recovered. The majority of
C. hyointestinalis
isolates with resistance to tetracycline were obtained from cohorts within a single pen, and most of these isolates were recovered from cattle during feeding of a forage-based diet as opposed to a grain-based diet. The findings of this study show that the subtherapeutic administration of tetracycline, alone and in combination with sulfamethazine, to feedlot cattle can select for the carriage of resistant strains of
Campylobacter
species. Considering the widespread use of in-feed antimicrobial agents and the high frequency of beef cattle that shed campylobacters, the development of AMR should be monitored as part of an on-going surveillance program.
Quantitative Detection of
Clostridium perfringens
in the Broiler Fowl Gastrointestinal Tract by Real-Time PCR
Authors: Wise Mark G. , Siragusa Gregory R.
Published: July 2005

Strains of
Clostridium perfringens
are a frequent cause of food-borne disease and gas gangrene and are also associated with necrotic enteritis in chickens. To detect and quantify the levels of
C. perfringens
in the chicken gastrointestinal tract, a quantitative real-time PCR assay utilizing a fluorogenic, hydrolysis-type probe was developed and utilized to assay material retrieved from the broiler chicken cecum and ileum. Primers and probe were selected following an alignment of 16S rDNA sequences from members of cluster I of the genus
Clostridium
, and proved to be specific for
C. perfringens
. The assay could detect approximately 50 fg of
C. perfringens
genomic DNA and approximately 20 cells in pure culture. Measurements of the analytical sensitivity determined with spiked intestinal contents indicated that the consistent limit of detection with ileal samples was approximately 10
2
CFU/g of ileal material, but only about 10
4
CFU/g of cecal samples. The decreased sensitivity with the cecal samples was due to the presence of an unidentified chemical PCR inhibitor(s) in the cecal DNA purifications. The assay was utilized to rapidly detect and quantify
C. perfringens
levels in the gut tract of broiler chickens reared without supplementary growth-promoting antibiotics that manifested symptoms of necrotic enteritis. The results illustrated that quantitative real-time PCR correlates well with quantification via standard plate counts in samples taken from the ileal region of the gastrointestinal tract.
Highly Hydrolytic Reuteransucrase from Probiotic
Lactobacillus reuteri
Strain ATCC 55730
Authors: Kralj S. , Stripling E. , Sanders P. , van Geel-Schutten G. H. , Dijkhuizen L.
Published: July 2005

Lactobacillus reuteri
strain ATCC 55730 (LB BIO) was isolated as a pure culture from a Reuteri tablet purchased from the BioGaia company. This probiotic strain produces a soluble glucan (reuteran), in which the majority of the linkages are of the α-(1→4) glucosidic type (∼70%). This reuteran also contains α-(1→6)- linked glucosyl units and 4,6-disubstituted α-glucosyl units at the branching points. The LB BIO glucansucrase gene (
gtfO
) was cloned and expressed in
Escherichia coli
, and the GTFO enzyme was purified. The recombinant GTFO enzyme and the LB BIO culture supernatants synthesized identical glucan polymers with respect to linkage type and size distribution. GTFO thus is a reuteransucrase, responsible for synthesis of this reuteran polymer in LB BIO. The preference of GTFO for synthesizing α-(1→4) linkages is also evident from the oligosaccharides produced from sucrose with different acceptor substrates, e.g., isopanose from isomaltose. GTFO has a relatively high hydrolysis/transferase activity ratio. Complete conversion of 100 mM sucrose by GTFO nevertheless yielded large amounts of reuteran, although more than 50% of sucrose was converted into glucose. This is only the second example of the isolation and characterization of a reuteransucrase and its reuteran product, both found in different
L. reuteri
strains. GTFO synthesizes a reuteran with the highest amount of α-(1→4) linkages reported to date.
Rickettsia
Symbiont in the Pea Aphid
Acyrthosiphon pisum
: Novel Cellular Tropism, Effect on Host Fitness, and Interaction with the Essential Symbiont
Buchnera
Authors: Sakurai Makiko , Koga Ryuichi , Tsuchida Tsutomu , Meng Xian-Ying , Fukatsu Takema
Published: July 2005

In natural populations of the pea aphid
Acyrthosiphon pisum
, a facultative bacterial symbiont of the genus
Rickettsia
has been detected at considerable infection frequencies worldwide. We investigated the effects of the
Rickettsia
symbiont on the host aphid and also on the coexisting essential symbiont
Buchnera
. In situ hybridization revealed that the
Rickettsia
symbiont was specifically localized in two types of host cells specialized for endosymbiosis: secondary mycetocytes and sheath cells. Electron microscopy identified bacterial rods, about 2 μm long and 0.5 μm thick, in sheath cells of
Rickettsia
-infected aphids. Virus-like particles were sometimes observed in association with the bacterial cells. By an antibiotic treatment, we generated
Rickettsia
-infected and
Rickettsia
-eliminated aphid strains with an identical genetic background. Comparison of these strains revealed that
Rickettsia
infection negatively affected some components of the host fitness. Quantitative PCR analysis of the bacterial population dynamics identified a remarkable interaction between the coexisting symbionts:
Buchnera
population was significantly suppressed in the presence of
Rickettsia
, particularly at the young adult stage, when the aphid most actively reproduces. On the basis of these results, we discussed the possible mechanisms that enable the prevalence of
Rickettsia
infection in natural host populations in spite of the negative fitness effects observed in the laboratory.
Rapid Method for Enumeration of Viable
Legionella pneumophila
and Other
Legionella
spp. in Water
Authors: Delgado-Viscogliosi Pilar , Simonart Tristan , Parent Virginie , Marchand Grégory , Dobbelaere Marie , Pierlot Eric , Pierzo Véronique , Menard-Szczebara Florence , Gaudard-Ferveur Elisabeth , Delabre Karine , Delattre Jean Marie
Published: July 2005

A sensitive and specific method has been developed to enumerate viable
L. pneumophila
and other
Legionella
spp. in water by epifluorescence microscopy in a short period of time (a few hours). This method allows the quantification of
L. pneumophila
or other
Legionella
spp. as well as the discrimination between viable and nonviable
Legionella
. It simultaneously combines the specific detection of
Legionella
cells using antibodies and a bacterial viability marker (ChemChrome V6), the enumeration being achieved by epifluorescence microscopy. The performance of this immunological double-staining (IDS) method was investigated in 38 natural filterable water samples from different aquatic sources, and the viable
Legionella
counts were compared with those obtained by the standard culture method. The recovery rate of the IDS method is similar to, or higher than, that of the conventional culture method. Under our experimental conditions, the limit of detection of the IDS method was <176
Legionella
cells per liter. The examination of several samples in duplicates for the presence of
L. pneumophila
and other
Legionella
spp. indicated that the IDS method exhibits an excellent intralaboratory reproducibility, better than that of the standard culture method. This immunological approach allows rapid measurements in emergency situations, such as monitoring the efficacy of disinfection shock treatments. Although its field of application is as yet limited to filterable waters, the double-staining method may be an interesting alternative (not equivalent) to the conventional standard culture methods for enumerating viable
Legionella
when rapid detection is required.
High-Level Expression and Secretion of Methyl Parathion Hydrolase in
Bacillus subtilis
WB800
Authors: Zhang Xiao-Zhou , Cui Zhong-Li , Hong Qing , Li Shun-Peng
Published: July 2005

The methyl parathion hydrolase (MPH)-encoding gene
mpd
was placed under the control of the P43 promoter and
Bacillus subtilis nprB
signal peptide-encoding sequence. High-level expression and secretion of mature, authentic, and stable MPH were achieved using the protease-deficient strain
B. subtilis
WB800 as the host.
Analysis of Microbial Gene Transcripts in Environmental Samples
Authors: Poretsky Rachel S. , Bano Nasreen , Buchan Alison , LeCleir Gary , Kleikemper Jutta , Pickering Maria , Pate Whitney M. , Moran Mary Ann , Hollibaugh James T.
Published: July 2005

We analyzed gene expression in marine and freshwater bacterioplankton communities by the direct retrieval and analysis of microbial transcripts. Environmental mRNA, obtained from total RNA by subtractive hybridization of rRNA, was reverse transcribed, amplified with random primers, and cloned. Approximately 400 clones were analyzed, of which ∼80% were unambiguously mRNA derived. mRNAs appeared to be from diverse taxonomic groups, including both
Bacteria
(mainly α- and γ-
Proteobacteria
) and
Archaea
(mainly
Euryarchaeota
). Many transcripts could be linked to environmentally important processes such as sulfur oxidation (
soxA
), assimilation of C1 compounds (
fdh1B
), and acquisition of nitrogen via polyamine degradation (
aphA
). Environmental transcriptomics is a means of exploring functional gene expression within natural microbial communities without bias toward known sequences, and provides a new approach for obtaining community-specific variants of key functional genes.
Elucidating the Key Member of a Linuron-Mineralizing Bacterial Community by PCR and Reverse Transcription-PCR Denaturing Gradient Gel Electrophoresis 16S rRNA Gene Fingerprinting and Cultivation
Authors: Sørensen Sebastian R. , Rasmussen Jim , Jacobsen Carsten S. , Jacobsen Ole S. , Juhler René K. , Aamand Jens
Published: July 2005

A bacterial community from Danish agricultural soil was enriched with linuron [
N
-(3,4-dichlorophenyl)-
N
′-methoxy-
N
′-methylurea] as the sole carbon and nitrogen source. The community mineralized [
ring
-U-
14
C]linuron completely to
14
CO
2
and
14
C-biomass. Denaturing gradient gel electrophoresis analysis and cultivation revealed that a
Variovorax
sp. was responsible for the mineralization activity.
Use of Peptide Library Screening To Detect a Previously Unknown Linear Diagnostic Epitope: Proof of Principle by Use of Lyme Disease Sera
Authors: Hamby Carl V. , Llibre Marta , Utpat Sandeepa , Wormser Gary P.
Published: July 2005

Diagnostic peptides previously isolated from phage-displayed libraries by affinity selection with serum antibodies from patients with Lyme disease were found to give reproducible serum reactivity patterns when tested in two different enzyme-linked immunosorbent assay formats. In addition, the hypothetical possibility that peptides selected by this type of “epitope discovery” technique might identify the original antigens eliciting antibody responses was tested by searching for sequence similarities in bacterial protein databases. In support of this hypothesis, our search uncovered similarities between peptides representing two different sequence motifs and sequences in the VlsE and BBA61 antigens ofBorrelia burgdorferi. Utilizing synthetic peptides, we verified that the sequence KAASKETPPALNK, located at the C terminus of the VlsE antigen, had the same reactivity pattern to sera from patients with extracutaneous Lyme disease as the diagnostic peptideSKEKPPSLNWPA, with which it shared a 7-amino-acid-residue match (consensus residues are underlined). A peptide with conservative mutations of five of the consensus residues was nonreactive, strongly suggesting that the VlsE sequence represents the epitope that originally elicited antibody responses in these patients. The diagnostic sensitivity of this new VlsE epitope was relatively low (30%) compared to that (100%) of the well-documented C6diagnostic peptide of VlsE when tested in our small cohort of 10 patients with Lyme disease. Nonetheless, the identification of this previously unknown epitope serves as a proof of the principle of the hypothetical ability of “epitope discovery” techniques to detect specific microbial antigens with diagnostic relevance in infectious diseases.
Immunoglobulin G Subclass Profile of Antimeasles Response in Vaccinated Children and in Adults with Measles History
Authors: Toptygina Anna P. , Pukhalsky Alexander L. , Alioshkin Vladimir A.
Published: July 2005

The aim of this study was to investigate measles-specific immunoglobulin G (IgG) subclass profile in vaccinated children and in adults with natural infection. Serum samples were collected before and 30 days after vaccination. The sera from 51 late convalescent adults and seven adults with natural measles infection at the 12th day after onset of rash have been also investigated. Measles IgG antibodies and specific IgG subclasses were tested by enzyme-linked immunosorbent techniques. In children younger than 3 years, the predominant subclass was IgG3, which contributed, on average, 63.3% of the total IgG response. The contributions of specific IgG1 and IgG4 to the total IgG antimeasles response were lower (19.9% and 16.8%, respectively), whereas IgG2 was not found. In contrast, in the group of children older than 4 years, just IgG2 was a predominant subclass; it contributed 42.6% of the total IgG response. Other subclasses were also present but the contribution was much lower. In adult volunteers with measles history, IgG2 was a predominant subclass of total IgG. Thus, in early convalescence IgG2 contributed 62% of the total IgG response, whereas in late convalescence the contribution was lower (41.4%). There were no visible differences in IgG subclass composition between subjects with natural infection and vaccinated children except those below 3 years of age. The humoral immune response of such subjects is immature and the IgG2 subclass of virus-specific antibodies has not been revealed in the sera.
Enzyme-Linked Immunosorbent Assay Based on a Chimeric Antigen Bearing Antigenic Regions of Structural Proteins E
rns
and E2 for Serodiagnosis of Classical Swine Fever Virus Infection
Authors: Lin Min , Trottier Erin , Mallory Maria
Published: July 2005

The antigenic region (residues 109 to 160) of classical swine fever virus (CSFV) protein E
rns
and the N-terminal antigenic region (residues 1 to 136) of protein E2 were constructed in the form of a fused, chimeric protein, C21E
rns
E2, for use as an enzyme-linked immunosorbent assay (ELISA) antigen for the serodiagnosis of CSFV infection. Tested with 238 negative-field (CSFV-free) sera from Canadian sources, the specificity of the ELISA was determined to be 93.7%. All 20 sera from experimentally infected pigs representing a variety of animals, virus strains, and days postinfection (dpi; range, 7 to 210) were detected as positive (100%). In contrast, an ELISA based on an E
rns
fragment (E
rns
aa 109-160
) or an E2 fragment (E2
aa 1-221
) identified only 18 (90%) of 20 sera from infected pigs as positive, missing two targets collected at 7 dpi. These data suggest that use of the chimeric antigen C21E
rns
E2 would improve serodiagnostic sensitivity and allow for the detection of CSFV infection as early as 7 dpi.
Unique Aspects of Gene Expression during
Candida albicans
Mating and Possible G
1
Dependency
Authors: Zhao Rui , Daniels Karla J. , Lockhart Shawn R. , Yeater Kathleen M. , Hoyer Lois L. , Soll David R.
Published: July 2005

Taking advantage of the high frequency of conjugation tube formation in mating mixtures and α-pheromone-treated
a
/
a
cells derived from saturation phase cultures of opaque cells of
Candida albicans
, 56 up-regulated and 30 down-regulated genes were identified employing microarray and Northern analyses. Combining these results with previous profiling studies of pheromone-induced cells, a more comprehensive transcript profile was developed for comparison with
Saccharomyces cerevisiae
. This comparison revealed the following: (i) that while a majority of mating-associated genes are regulated similarly between the two species, a significant minority are regulated dissimilarly; (ii) that filamentation genes are uniquely up-regulated and opaque-specific genes uniquely down-regulated during
C. albicans
mating; and (iii) that a newly identified class of genes is selectively down-regulated in opaque, but not white, cells that have entered saturation phase in a growth culture and then are up-regulated by pheromone. The observations that opaque cells are uniquely mating competent, that saturation phase facilitates mating, and that a newly identified group of genes is down-regulated only in opaque cells that have entered saturation phase led us to hypothesize that entering saturation phase may be requisite for mating. A test of this hypothesis revealed, however, that cells, whether in the exponential or saturation phase, may simply have to be in G
1
of the cell cycle to respond to pheromone and that the response includes G
1
arrest. These results add to the lists of similarities and dissimilarities between the mating processes of
C. albicans
and
S. cerevisiae
and underscore the unique regulation of filamentation and switching genes in the
C. albicans
mating process.
Hyphal Growth in the Fission Yeast
Schizosaccharomyces pombe
Authors: Amoah-Buahin Evelyn , Bone Neil , Armstrong John
Published: July 2005

The fission yeast
Schizosaccharomyces pombe
grows in a single-celled form or can mate and undergo meiosis and sporulation. Here we show that wild-type
S. pombe
can also differentiate to form elaborately branched hyphae which invade deep into solid medium. Branches appear in the hyphae adjacent to unseparated septa. Electron microscopy reveals unusual multivesicular structures within the hyphae. Nitrogen deprivation appears to be the main stimulus for hyphal growth. No mitogen-activated protein kinase is necessary for the response. Inhibition of cyclic AMP (cAMP) production or signaling prevents the response, and exogenous cAMP promotes it, suggesting that detection of a good carbon source is required for hyphal growth but not for mating.
THE INFLUENCE OF THE GAUGE BOSON MASS ON THE CRITICAL NUMBER OF THE FERMION FLAVORS IN QED3
Authors: FENG HONG-TAO , SUN WEI-MIN , HU FEI , ZONG HONG-SHI
Published: July 2005

Using the Dyson–Schwinger equations for the propagators of fermion and gauge boson with a nonzero mass, we investigate the effects of the full vacuum polarization and vertex on the fermion propagators in QED3 with N fermion flavors. We find that the critical number of the fermion flavors is affected appreciably by the gauge boson mass and depend on the form of the full vertex function Ansatz.
SMALL WORLD AND SCALE FREE MODEL OF TRANSMISSION OF SARS
Authors: SMALL MICHAEL , TSE CHI K.
Published: July 2005

We model transmission of the Severe Acute Respiratory Syndrome (SARS) associated coronavirus (SARS-CoV) in Hong Kong with a complex small world network. Each node in the network is connected to its immediate neighbors and a random number of geographically isolated nodes. Transmission can only occur along these links. We find that this model exhibits dynamics very similar to those observed during the SARS outbreak in 2003. We derive an analytic expression for the rate of infection and confirm this expression with computational simulations. An immediate consequence of this quantity is that the severity of the SARS epidemic in Hong Kong in 2003 was due to ineffectual infection control in hospitals (i.e. nosocomial transmission). If all infectious individuals were isolated as rapidly as they were identified the severity of the outbreak would have been minimal.
FIELD PROGRAMMABLE ANALOG ARRAY TO IMPLEMENT A PROGRAMMABLE CHUA'S CIRCUIT
Authors: CAPONETTO RICCARDO , DI MAURO ANDREA , FORTUNA LUIGI , FRASCA MATTIA
Published: July 2005

This paper introduces a new application of the Field Programmable Analog Array. Ease of design and reprogrammability are the advantages offered by this class of analog circuits, making them an ideal environment for the implementation of chaotic circuits and their experimental characterization.

Chua's circuit, a well-known paradigm of nonlinear circuits, has been used as an example of application. Experimental results show the suitability of the approach, highlighting the features of the new implementation: a fully on the fly programmable Chua's circuit has been obtained.
HOPF BIFURCATION OF A TWO-NEURON NETWORK WITH DIFFERENT DISCRETE TIME DELAYS
Authors: LI SHAOWEN , LIAO XIAOFENG , LI CHUNGUANG , WONG KWOK-WO
Published: July 2005

In this paper, a two-neuron network with different time delays is investigated. By analyzing the associated characteristic equation, we obtain the conditions for delay-dependent and delay-independent asymptotic stability, respectively. Furthermore, we find that if the delay is used as a bifurcation parameter, Hopf bifurcation would occur. The direction and stability of the bifurcating periodic solutions are determined by using the Nyquist criterion and the graphical Hopf bifurcation theorem. Some examples are included to illustrate our results.
NONLINEAR OSCILLATORS WITH HYSTERETIC CHUA'S DIODES
Authors: ITOH MAKOTO , CHUA LEON O.
Published: July 2005

Chua's diode is widely used in nonlinear circuit analysis and modeling. In this paper, we propose canonical oscillator models having hysteretic Chua's diodes as their nonlinear elements. Many hysteresis oscillators can be classified into unified groups by using these models. We also present a method for deriving new hysteresis oscillators from known slow–fast (relaxation) oscillators.
AN ACOUSTIC FINITE-DIFFERENCE TIME-DOMAIN ALGORITHM WITH ISOTROPIC DISPERSION
Authors: WAGNER CHRISTOPHER L. , SCHNEIDER JOHN B.
Published: July 2005

The classic Yee Finite-Difference Time-Domain (FDTD) algorithm employs central differences to achieve second-order accuracy, i.e., if the spatial and temporal step sizes are reduced by a factor of n, the phase error associated with propagation through the grid will be reduced by a factor of n2. The Yee algorithm is also second-order isotropic meaning the error as a function of the direction of propagation has a leading term which depends on the square of the discretization step sizes. An FDTD algorithm is presented here that has second-order accuracy but fourth-order isotropy. This algorithm permits a temporal step size 50% larger than that of the three-dimensional Yee algorithm. Pressure-release resonators are used to demonstrate the behavior of the algorithm and to compare it with the Yee algorithm. It is demonstrated how the increased isotropy enables post-processing of the simulation spectra to correct much of the dispersion error. The algorithm can also be optimized at a specified frequency, substantially reducing numerical errors at that design frequency. Also considered are simulations of scattering from penetrable spheres ensonified by a pulsed plane wave. Each simulation yields results at multiple frequencies which are compared to the exact solution. In general excellent agreement is obtained.
LARGE DEFLECTION STATIC AND DYNAMIC ANALYSIS OF THIN CIRCULAR PLATES RESTING ON TWO-PARAMETER ELASTIC FOUNDATION: HDQ/FD COUPLED METHODOLOGY APPROACHES
Authors: CİVALEK ÖMER
Published: July 2005

An analysis of the geometrically nonlinear dynamics of thin circular plates on a two parameter elastic foundation is presented in this paper. The nonlinear partial differential equations obtained from von Karman's large deflection plate theory have been solved by using the harmonic differential quadrature method in the space domain and the finite difference numerical integration method in the time domain. Winkler-Pasternak foundation model is considered and the influence of stiffness of Winkler (K) and Pasternak (G) foundation on the geometrically nonlinear analysis of the circular plates has been investigated.

Numerical examples demonstrate the satisfactory accuracy, efficiency and versatility of the presented approach. From the numerical computation, it can be concluded that the present coupled methodology is an efficient method for the nonlinear static and dynamic analysis of circular plates with or without an elastic medium.
(+)Insert smooth muscle myosin heavy chain (SM-B) isoform expression in human tissues
Authors: Léguillette Renaud , Gil Fulvio R. , Zitouni Nedjma , Lajoie-Kadoch Stéphane , Sobieszek Apolinary , Lauzon Anne-Marie
Published: July 2005

Two smooth muscle myosin heavy chain isoforms differ in their amino terminus by the presence [(+)insert] or absence [(−)insert] of a seven-amino acid insert. Animal studies show that the (+)insert isoform is predominantly expressed in rapidly contracting phasic muscle and the (−)insert isoform is mostly found in slowly contracting tonic muscle. The expression of the (+)insert isoform has never been demonstrated in human smooth muscle. We hypothesized that the (+)insert isoform is present in humans and that its expression is commensurate with the organ's functional requirements. We report, for the first time, the sequence of the human (+)insert isoform and quantification of its expression by real-time PCR and Western blot analysis in a panel of human organs. The (+)insert isoform mRNA and protein expression levels are significantly greater in small intestine compared with all organs studied except for trachea and are significantly greater in trachea compared with uterus and aorta. To assess the functional significance of this differential myosin isoform expression between organs, we measured the rate of actin filament movement (νmax) when propelled by myosin purified from rat organs, because the rat and human inserts are identical and their remaining sequences show 93% identity. νmax exhibits a rank correlation from the most tonic to the most phasic organ. The selective expression of the (+)insert isoform observed among human organs suggests that it is an important determinant of tissue shortening velocity. A differential expression of the (+)insert isoform could also account for altered contractile properties observed in human pathology.
Laminar Organization of Response Properties in Primary Visual Cortex of the Gray Squirrel(Sciurus carolinensis)
Authors: Heimel J. Alexander , Van Hooser Stephen D. , Nelson Sacha B.
Published: July 2005

The gray squirrel ( Sciurus carolinensis) is a diurnal highly visual rodent with a cone-rich retina. To determine which features of visual cortex are common to highly visual mammals and which are restricted to non-rodent species, we studied the laminar organization of response properties in primary visual area V1 of isoflurane-anesthetized squirrels using extra-cellular single-unit recording and sinusoidal grating stimuli. Of the responsive cells, 75% were tuned for orientation. Only 10% were directionally selective, almost all in layer 6, a layer receiving direct input from the dorsal lateral geniculate nucleus (LGN). Cone opponency was widespread but almost absent from layer 6. Median optimal spatial frequency tuning was 0.21 cycles/°. Median optimal temporal frequency a high 5.3 Hz. Layer 4 had the highest percentage of simple cells and shortest latency (26 ms). Layers 2/3 had the lowest spontaneous activity and highest temporal frequency tuning. Layer 5 had the broadest spatial frequency tuning and most spontaneous activity. At the layer 4/5 border were sustained cells with high cone opponency. Simple cells, determined by modulation to drifting sinusoidal gratings, responded with shorter latencies, were more selective for orientation and direction, and were tuned to lower spatial frequencies. A comparison with other mammals shows that although the laminar organization of orientation selectivity is variable, the cortical input layers contain more linear cells in most mammals. Nocturnal mammals appear to have more orientation-selective neurons in V1 than diurnal mammals of similar size.
Affects of Aging on Receptive Fields in Rat Primary Auditory Cortex Layer V Neurons
Authors: Turner Jeremy G. , Hughes Larry F. , Caspary Donald M.
Published: July 2005

Advanced age is commonly associated with progressive cochlear pathology and central auditory deficits, collectively known as presbycusis. The present study examined central correlates of presbycusis by measuring response properties of primary auditory cortex (AI) layer V neurons in the Fischer Brown Norway rat model. Layer V neurons represent the major output of AI to other cortical and subcortical regions (primarily the inferior colliculus). In vivo single-unit extracellular recordings were obtained from 114 neurons in aged animals (29–33 mo) and compared with 105 layer V neurons in young-adult rats (4–6 mo). Three consecutive repetitions of a pure-tone receptive field map were run for each neuron. Age was associated with fewer neurons exhibiting classic V/U-shaped receptive fields and a greater percentage of neurons with more Complex receptive fields. Receptive fields from neurons in aged rats were also less reliable on successive repetitions of the same stimulus set. Aging was also associated with less firing during the stimulus in V/U-shaped receptive field neurons and more firing during the stimulus in Complex neurons, which were generally associated with inhibited firing in young controls. Finally, neurons in aged rats with Complex receptive fields were more easily driven by current pulses delivered to the soma. Collectively, these findings provide support for the notion that age is associated with diminished signal-to-noise coding by AI layer V neurons and are consistent with other research suggesting that GABAergic neurotransmission in AI may be compromised by aging.
Stratum corneum Lipids and Water
Authors: Wertz Philip W.
Published: July 2005

Lipids in the intercellular spaces of the stratum corneum provide the permeability barrier of the skin. The primary function of the barrier is to prevent water loss to the environment. Secondarily, the barrier limits or prevents the penetration of potentially toxic substances that may contact the skin surface. The main lipids comprising the barrier are ceramides, cholesterol and long-chain saturated fatty acids. The ceramides are structurally heterogenous. In the human, there are 9 series of ceramides. Three of these are acylceramides consisting of long ω-hydroxy acids amide-linked to a long-chain base and bearing linoleate ester-linked to the ω-hydroxyl group. The base component can be sphingosine, phytosphingosine or 6-hydroxysphingosine. The other ceramides contain normal or α-hydroxy acids amide-linked to one of these bases. Linoleate is an essential fatty acid, without which the barrier of the skin cannot be maintained. This is thought to be reflected in the roles of the acylceramides in barrier formation and function. The intercellular lipids of the stratum corneum are organized into elaborate multilamellar structures. Water molecules hydrogen bond to polar head groups of the lamellae; however, there is no free water between the lamellae. Most of the water in the stratum corneum is inside the corneocytes. In a variety of pathological conditions, the lipid composition and organization are altered, leading to a reduced capacity to hold water and increased transepidermal water loss.
Revisiting the plagues in Psalm cv
Authors: Tucker W. Dennis
Published: July 2005

In revisiting the plagues in Ps. cv, this study suggests that the omission of the fifth and sixth plagues and the repositioning of the ninth plague may be credited to the psalmist's interest in stressing the significance of land in the history of Israel.
Exilic and post-exilic prophecy and the orality/literacy problem
Authors: Schaper Joachim
Published: July 2005

This paper explores the uses of writing as documented in late pre-exilic and especially in exilic and post-exilic Judaean prophetic texts in the context of the orality/literacy debate. It delineates the impact the rising importance of writing had on Judaean prophecy and attempts to show that writing as a new "technology of the intellect" (J. Goody) irreversibly altered the character of Judaean prophecy. The paper also demonstrates that the concept of an orality/literacy continuum is likely to distort our view of the significance of writing in Israelite prophecy—and, indeed, of Israelite history as a whole. Against this background, it makes sense to reconsider the relationship between prophecy and scribalism. The passages from exilic and post-exilic prophetic texts discussed in the present paper indicate that, from the late pre-exilic period onwards, the contacts between prophets and priests/scribes became closer and closer.
Peroneus Longus Muscle Activation Pattern during Gait Cycle in Athletes Affected by Functional Ankle Instability
Authors: Santilli Valter , Frascarelli Massimo A. , Paoloni Marco , Frascarelli Flaminia , Camerota Filippo , De Natale Luisa , De Santis Fabio
Published: July 2005

Background

Functional ankle instability is a clinical syndrome that may develop after acute lateral ankle sprain. Although several causes of this functional instability have been suggested, it is still unclear what the activation pattern of the peroneus longus muscle is in patients with functional ankle instability.

Hypothesis

Peroneus longus activation patterns differ in the injured side and the uninjured side in subjects with functional ankle instability.

Study Design

Descriptive laboratory study.

Methods

The authors examined 14 subjects with functional ankle instability by using surface electromyography during walking. Activation time of the peroneus longus muscle was expressed as a percentage of the stance phase of the gait cycle.

Results

A statistically significant decrease in peroneus longus muscle activity was found in the injured side compared with the uninjured side (22.8% ± 4.25% vs 37.6% ± 3.5%, respectively).

Conclusions

Results obtained in this study show a change in peroneus longus muscle activation time after injury. Independent of the origin of this change, which could only be surmised, the decrease in peroneus longus muscle activity may result in reduced protection against lateral sprains.

Clinical Relevance

The assessment of peroneus longus activation pattern during gait is useful to design an appropriate rehabilitation program in athletes suffering from functional ankle instability.
A Place to Sit
Authors: McColgan Gillian
Published: July 2005

Based on a study of people with dementia living in a nursing home, this article examines the impact on residents of a surveillance culture and their responses to it. This discussion focuses on resistance strategies employed by residents to create private space in a public place. Residents frequently longed for home, a safe maternal place distanced from the nursing home. Selecting a place to sit signifies and encapsulates the essence of findings from this ethnography and is used to illustrate the irony of denying even this choice to residents when sitting is one of the few activities they do. Going beyond previous work, this article provides an extensive exploration of resident resistance to a nursing home and shows people with dementia actively creating privacy and something resembling home.
Increased copy number at 3p14 in breast cancer
Authors: Ljuslinder Ingrid , Malmer Beatrice , Golovleva Irina , Thomasson Marcus , Grankvist Kjell , Höckenström Thomas , Emdin Stefan , Jonsson Yvonne , Hedman Håkan , Henriksson Roger
Published: July 2005

Introduction

The present study was conducted to investigate if chromosome band 3p14 is of any pathogenic significance in the malignant process of breast cancer. Genetic studies have implicated a tumour suppressor gene on chromosome arm 3p and we have proposed LRIG1 at 3p14 as a candidate tumour suppressor. The LRIG1 gene encodes an integral membrane protein that counteracts signalling by receptor tyrosine kinases belonging to the ERBB family. LRIG1 mRNA and protein are expressed in many tissues, including breast tissue.

Methods

In the present report we analysed the LRIG1 gene by fluorescence in situ hybridisation (FISH), LRIG1 mRNA by quantitative RT-PCR, and LRIG1 protein by western blot analysis. Two tumour series were analysed; one series consisted of 19 tumour samples collected between 1987 and 1995 and the other series consisted of 9 tumour samples with corresponding non-neoplastic breast tissues collected consecutively.

Results

The LRIG1 gene showed increased copy number in 11 out of 28 tumours (39%) and only one tumour showed a deletion at this locus. Increased LRIG1 copy number was associated with increased levels of LRIG1 mRNA (two of three tumours) and protein (four of four tumours) in the tumours compared to matched non-neoplastic breast tissue, as assessed by RT-PCR and western blot analysis.

Conclusion

The molecular function of LRIG1 as a negative regulator of ERBB receptors questions the biological significance of increased LRIG1 copy number in breast cancer. We propose that a common, but hitherto unrecognised, breast cancer linked gene is located within an amplicon containing the LRIG1 locus at 3p14.3.
Psychometric evaluation of the Energy Conservation Strategies Survey
Authors: Mallik Priyanka S , Finlayson Marcia , Mathiowetz Virgil , Fogg Louis
Published: July 2005

Objective: To examine the internal consistency and test-retest reliability of the Energy Conservation Strategies Survey (ECSS), a tool that was specifically designed to determine if people with multiple sclerosis who attended the six-week energy conservation course actually implemented the strategies taught to them.

Design: The instrument ECSS was administered at six weeks and seven weeks post intervention to evaluate the test-retest reliability, while data from six weeks post intervention were utilized to assess the internal consistency of the ECSS.

Setting: Community locations in Illinois and Minnesota, USA.

Subjects: Data from 53 participants with multiple sclerosis living in the community were utilized for the psychometric study.

Measures: Energy Conservation Strategies Survey.

Results: The internal consistency of 0.92 reveals that all the items are consistent with each other and measure a single construct. Inferential analyses using intraclass correlation coefficient indicates good test-retest reliability (intraclass correlation coefficient (ICC)=0.79).

Conclusion: Findings of the study suggest that the ECSS exhibits high internal consistency and good test-retest reliability. The study implies that the ECSS could be valuable in measuring changes in behavior over time among people with multiple sclerosis after the completion of the six-week energy conservation course provided by occupational therapists.
Endoscopic Techniques to Diagnose and Manage Biliary Tumors
Authors: Brugge William R.
Published: July 2005

Malignancies of the bile duct are often suspected in patients with abnormal serum hepatic enzyme levels and obstruction of the biliary system. Although cross-sectional imaging can provide evidence for biliary obstruction and a malignancy arising from the bile duct, a definitive diagnosis is often obtained through the use of endoscopic procedures. Endoscopic retrograde cholangiopancreatography (ERCP), the most commonly performed procedure for cholangiocarcinoma, can provide a tissue diagnosis through brush cytology of the bile duct. Relief from biliary obstruction can be provided with temporary plastic stenting or permanent metal stenting. Photodynamic therapy guided by ERCP may provide improved palliation from biliary obstruction in the future. Endoscopic ultrasonography complements the role of ERCP and may provide a tissue diagnosis through fine-needle aspiration and staging through ultrasound imaging. High-resolution ultrasound images can provide detailed information regarding the relationship between a mass and the bile duct wall. Despite these advances in endoscopic techniques and imaging of the bile duct, a tissue diagnosis often remains elusive in many patients. In the future, molecular markers will be employed to improve the sensitivity for the detection of malignancy in bile duct samples obtained through brushing, aspiration, and biopsy.
Role of Endoscopic Ultrasonography in the Staging and Follow-Up of Esophageal Cancer
Authors: Lightdale Charles J. , Kulkarni Ketan G.
Published: July 2005

Purpose

To evaluate the role of endoscopic ultrasonography (EUS) in the initial staging and follow-up of esophageal cancer on the basis of a review of the published literature.

Methods

Articles published from 1985 to 2005 were searched and reviewed using the following keywords: “esophageal cancer staging,” “endoscopic ultrasound,” and “endoscopic ultrasonography.”

Results

For initial anatomic staging, EUS results have consistently shown more than 80% accuracy compared with surgical pathology for depth of tumor invasion (T). Accuracy increased with higher stage, and was >90% for T3 cancer. EUS results have shown accuracy in the range of 75% for initial staging of regional lymph nodes (N). EUS has been invariably more accurate than computed tomography for T and N staging. EUS is limited for staging distant metastases (M), and therefore EUS is usually performed after a body imaging modality such as computed tomography or positron emission tomography. Pathologic staging can be achieved at EUS using fine-needle aspiration (FNA) to obtain cytology from suspect Ns. FNA has had greatest efficacy in confirming celiac axis lymph node metastases with more than 90% accuracy. EUS is inaccurate for staging after radiation and chemotherapy because of inability to distinguish inflammation and fibrosis from residual cancer, but a more than 50% decrease in tumor cross-sectional area or diameter has been found to correlate with treatment response.

Conclusion

EUS has a central role in the initial anatomic staging of esophageal cancer because of its high accuracy in determining the extent of locoregional disease. EUS is inaccurate for staging after radiation therapy and chemotherapy, but can be useful in assessing treatment response.