bluuebunny/crossref_metadata_2025 huggingface dataset:
Bovine Ileal Intraepithelial Lymphocytes Represent Target Cells for Shiga Toxin 1 fromEscherichia coli
Authors: Menge Christian , Blessenohl Maike , Eisenberg Tobias , Stamm Ivonne , Baljer Georg
Published: March 2004

The discovery that bovine peripheral lymphocytes are sensitive to Stx1 identified a possible mechanism for the persistence of infections with Shiga toxin (Stx)-producingEscherichia coli(STEC) in the bovine reservoir host. If intraepithelial lymphocytes (IEL) are also sensitive to Stx1, the idea that Stx1 affects inflammation in the bovine intestine is highly attractive. To prove this hypothesis, ileal IEL (iIEL) were prepared from adult cattle, characterized by flow cytometry, and subjected to functional assays in the presence and absence of purified Stx1. We found that 14.9% of all iIEL expressed Gb3/CD77, the Stx1 receptor on bovine lymphocytes, and 7.9% were able to bind the recombinant B subunit of Stx1. The majority of Gb3/CD77+cells were activated CD3+CD6+CD8α+T cells, whereas only some CD4+T cells and B cells expressed Gb3/CD77. However, Stx1 blocked the mitogen-induced transformation to enlarged blast cells within all subpopulations to a similar extent and significantly reduced the percentage of Gb3/CD77+cells. Although Stx1 did not affect the natural killer cell activity of iIEL, the toxin accelerated the synthesis of interleukin-4 (IL-4) mRNA and reduced the amount of IL-8 mRNA in bovine iIEL cultures. Because the intestinal system comprises a rich network of interactions between different types of cells and any dysfunction may influence the course of intestinal infections, this demonstration that Stx1 can target bovine IEL may be highly relevant for our understanding of the interplay between STEC and its reservoir host.
TheMoraxella catarrhalisPorin-Like Outer Membrane Protein CD Is an Adhesin for Human Lung Cells
Authors: Holm Melissa M. , Vanlerberg Serena L. , Foley Ian M. , Sledjeski Darren D. , Lafontaine Eric R.
Published: March 2004

The outer membrane protein CD (OMPCD) ofMoraxella catarrhalisis an outer membrane protein with several attributes of a potential vaccine antigen. We isolated four transposon mutants of strain O35E on the basis of their reduced binding to A549 human lung cells in microcolony formation assays, and we determined that they contain a transposon inompCD. We also found that these transposon insertions had pleiotropic effects: mutants grew slower, became serum sensitive, bound ∼10-fold less to A549 cells, and appeared transparent when grown on solid medium. We confirmed that these various phenotypes could be attributed solely to disruption ofompCDby constructing the isogenic strain O35E.CD1. O35E-ompCDwas cloned, and recombinantEscherichia colibacteria expressing the gene product exhibited a 10-fold increase in adherence to A549 cells. This is the first report ofM. catarrhalis ompCDmutants, and our findings demonstrate that this gene product is an adhesin for human lung cells.
Role for Cystic Fibrosis Transmembrane Conductance Regulator Protein in a Glutathione Response to Bronchopulmonary
Pseudomonas
Infection
Authors: Day Brian J. , van Heeckeren Anna M. , Min Elysia , Velsor Leonard W.
Published: March 2004

The lung maintains an elevated level of glutathione (GSH) in epithelial lining fluid (ELF) compared to serum. The mechanism(s) by which the lung maintains high levels of ELF GSH and factors that modulate them are largely unexplored. We hypothesized that lung cystic fibrosis transmembrane conductance regulator protein (CFTR) modulates GSH efflux in response to extracellular stress, which occurs with lung infections. Mice were challenged intratracheally with
Pseudomonas aeruginosa
, and on the third day of infection bronchoalveolar lavage fluid was obtained and analyzed for cytokines and antioxidants. Lung tissue antioxidants and enzyme activities were also assessed.
P. aeruginosa
lung infection increased levels of inflammatory cytokines and neutrophils in the ELF. This corresponded with a marked threefold increase in GSH and a twofold increase in urate levels in the ELF of
P. aeruginosa
-infected wild-type mice. A twofold increase in urate levels was also observed among lung tissue antioxidants of
P. aeruginosa
-infected wild-type mice. There were no changes in markers of lung oxidative stress associated with the
P. aeruginosa
lung infection. In contrast with wild-type mice, the CFTR knockout mice lacked a significant increase in ELF GSH when challenged with
P. aeruginosa
, and this correlated with a decrease in the ratio of reduced to oxidized GSH in the ELF, a marker of oxidative stress. These data would suggest that the lung adapts to infectious agents with elevated ELF GSH and urate. Individuals with lung diseases associated with altered antioxidant transport, such as cystic fibrosis, might lack the ability to adapt to the infection and present with a more severe inflammatory response.
Flea-Borne Transmission Model To Evaluate Vaccine Efficacy against Naturally Acquired Bubonic Plague
Authors: Jarrett Clayton O. , Sebbane Florent , Adamovicz Jeffrey J. , Andrews Gerard P. , Hinnebusch B. Joseph
Published: March 2004

A flea-to-mouse transmission model was developed for use in testing new candidate vaccines for the ability to protect against flea-borne plague. The model was used to evaluate a recombinant fusion protein vaccine consisting of the
Yersinia pestis
F1 and V antigens. After one to three challenges with
Y. pestis
-infected fleas, 14 of 15 unvaccinated control mice developed plague, with an average septicemia level of 9.2 × 10
8
Y. pestis
CFU/ml. None of 15 vaccinated mice developed the disease after similar challenges, and serological testing indicated that transmitted bacteria were eliminated by the immune system before extensive replication and systemic infection could occur. The transmission and development of disease in control mice correlated with the number of bites by blocked fleas but not with the total number of fleabites. The model provides a means to directly assess the efficacy of new vaccines to prevent naturally acquired bubonic plague and to study events at the vector-host interface that lead to dissemination and disease.
Cell Envelope Protein PPE68 Contributes toMycobacterium tuberculosisRD1 Immunogenicity Independently of a 10-Kilodalton Culture Filtrate Protein and ESAT-6
Authors: Demangel Caroline , Brodin Priscille , Cockle Paul J. , Brosch Roland , Majlessi Laleh , Leclerc Claude , Cole Stewart T.
Published: March 2004

The protective efficacy ofMycobacterium bovisBCG can be markedly augmented by stable integration ofMycobacterium tuberculosisgenomic region RD1. BCG complemented with RD1 (BCG::RD1) encodes nine additional proteins. Among them, 10-kDa culture filtrate protein (CFP-10) and ESAT-6 (6-kDa early secreted antigenic target) are low-molecular-weight proteins that induce potent Th1 responses. Using pools of synthetic peptides, we have examined the potential immunogenicity of four other RD1 products (PE35, PPE68, Rv3878, and Rv3879c). PPE68, the protein encoded byrv3873, was the only one to elicit gamma interferon (IFN-γ)-producing cells in C57BL/6 mice infected withM. tuberculosis. Anti-PPE68 T cells were predominantly raised against an epitope mapped in the N-terminal end of the protein. Importantly, inactivation ofrv3873in BCG::RD1 did not modify CFP-10 and ESAT-6 secretion. Moreover, the generation of IFN-γ responses to these antigens following immunization with BCG::RD1 was independent of PPE68 expression. Taken together, these results show that PPE68 is an immunogenic product of the RD1 region, which does not interfere with the secretion and immunogenicity of CFP-10 and ESAT-6.
Fc-Dependent Polyclonal Antibodies and Antibodies to Outer Membrane Proteins A and B, but Not to Lipopolysaccharide, Protect SCID Mice against FatalRickettsia conoriiInfection
Authors: Feng Hui-Min , Whitworth Ted , Olano Juan P. , Popov Vsevolod L. , Walker David H.
Published: March 2004

An emphasis on cellular immunity againstRickettsiahas led to neglect of analysis of the role of antibody. The availability of an excellent mouse model of spotted fever rickettsiosis enabled investigation of a potential role of antibody in immunity toRickettsia conorii. C3H severe combined immunodeficiency (SCID) mice were passively transfused with monoclonal antibodies against rickettsial outer membrane protein A (OmpA), OmpB, or lipopolysaccharide (LPS), polyclonal anti-R. conoriiserum, Fab fragments of polyclonal antiserum, or no antibodies and then challenged 48 h later with 10 50% lethal doses (LD50) ofR. conorii. All mice that received monoclonal antibodies against OmpA and two of four mice that received monoclonal antibodies against OmpB or polyclonal antisera were completely protected, but the recipients of anti-LPS antibodies or the Fab fragments were not protected. Polyclonal antibody treatment of C3H SCID mice that had been infected with 10 LD50ofR. conorii4 or 5 days earlier prolonged the life of the infected mice from 10.4 to 22.5 days and resulted in decreased levels of infectious rickettsiae in the spleen and liver 24 and 48 h later. Treatment with protective antibodies resulted in the development of large aggregates ofR. conoriiantigens in splenic macrophages and intraphagolysosomal rickettsial death and digestion. The kinetics of development of antibodies toR. conoriidetermined by immunoblotting revealed antibodies to LPS on day 6 and antibodies to OmpA and OmpB on day 12, when recovery from the infection had already occurred. Antibodies to particular epitopes of OmpA and OmpB may protect against reinfection, but they may not play a key role in immunity against primary infection. Antibodies might be useful for treating infections with antibiotic-resistant organisms, and some B-cell epitopes should be included in a subunit vaccine.
Measuring the Effects of an Ever-Changing Environment on Malaria Control
Authors: McCutchan Thomas F. , Grim K. Christiana , Li Jun , Weiss Walter , Rathore Darmendar , Sullivan Margery , Graczyk Thaddeus K. , Kumar Sanjai , Cranfield Mike R.
Published: March 2004

The effectiveness of malaria control measures depends not only on the potency of the control measures themselves but also upon the influence of variables associated with the environment. Environmental variables have the capacity either to enhance or to impair the desired outcome. An optimal outcome in the field, which is ultimately the real goal of vaccine research, will result from prior knowledge of both the potency of the control measures and the role of environmental variables. Here we describe both the potential effectiveness of control measures and the problems associated with testing in an area of endemicity. We placed canaries with different immunologic backgrounds (e.g., naïve to malaria infection, vaccinated naïve, and immune) directly into an area where avian malaria,Plasmodium relictum, is endemic. In our study setting, canaries that are naïve to malaria infection routinely suffer approximately 50% mortality during their first period of exposure to the disease. In comparison, birds vaccinated and boosted with a DNA vaccine plasmid encoding the circumsporozoite protein ofP. relictumexhibited a moderate degree of protection against natural infection (P< 0.01). In the second year we followed the fate of all surviving birds with no further manipulation. The vaccinated birds from the first year were no longer statistically distinguishable for protection against malaria from cages of naïve birds. During this period, 36% of vaccinated birds died of malaria. We postulate that the vaccine-induced protective immune responses prevented the acquisition of natural immunity similar to that concurrently acquired by birds in a neighboring cage. These results indicate that dominant environmental parameters associated with malaria deaths can be addressed before their application to a less malleable human system.
Cytokine and Inducible Nitric Oxide Synthase mRNA Expression during Experimental Murine Cryptococcal Meningoencephalitis
Authors: Maffei Claudia M. L. , Mirels Laurence F. , Sobel Raymond A. , Clemons Karl V. , Stevens David A.
Published: March 2004

The immune events that take place in the central nervous system (CNS) during cryptococcal infection are incompletely understood. We used competitive reverse transcription-PCR to delineate the time course of the local expression of mRNAs encoding a variety of cytokines and inducible nitric oxide synthase (iNOS) during progressive murine cryptococcal meningoencephalitis and assessed the CNS inflammatory response using immunohistochemistry. Interleukin 18 (IL-18), transforming growth factor β1, and IL-12p40mRNAs were constitutively expressed in the brains of infected and uninfected mice; IL-2 mRNA was not detected at any time. Increased levels of transcripts corresponding to IL-1α, tumor necrosis factor alpha (TNF-α), and iNOS were detected as early as day 1 postinfection, with TNF-α rising by ∼30-fold and iNOS increasing by ∼5-fold by day 7. Each remained at these levels thereafter. IL-4, IL-6, and gamma interferon transcripts were detected on day 5, and IL-1β and IL-10 transcripts were detected beginning on day 7. Once detected, each remained at a relatively constant level through 28 days of infection. This cytokine profile does not suggest a polarized Th1 or Th2 response. Immunohistochemistry did not reveal inflammatory infiltrates before day 7, despite the presence of cryptococci. Intraparenchymal abscesses with inflammatory cells in their peripheries were found beginning on day 10. The infiltrates were comprised primarily of cells expressing CD4, CD8, or CD11b; low numbers of cells expressing CD45R/B220 were also present. The persistence ofCryptococcusobserved in the CNS may result from an ineffective immune response, perhaps owing to an insufficient anticryptococcal effector function of endogenous glial cells resulting from competing pro- and anti-inflammatory cytokines. These data detail the immune response in the brain and could be important for the future design of specific immunomodulatory therapies for this important opportunistic infection.
Pathology Affects Different Organs in Two Mouse Strains Chronically Infected by a
Trypanosoma cruzi
Clone: a Model for Genetic Studies of Chagas’ Disease
Authors: Marinho Claudio R. F. , Bucci Daniella Z. , Dagli Maria Lúcia Z. , Bastos Karina R. B. , Grisotto Marcos G. , Sardinha Luiz R. , Baptista Cristiane R. G. M. , Penha Gonçalves Carlos , Lima Maria Regina D’Império , Álvarez José M.
Published: March 2004

Chagas’ disease is a chronic infection caused by
Trypanosoma cruzi
and represents an important public health burden in Latin America. Frequently the disease evolves undetectable for decades, while in a significant fraction of the affected individuals it culminates in death by heart failure. Here, we describe a novel murine model of the chronic infection with
T. cruzi
using a stable clone isolated from a human patient (Sylvio X10/4). The infection in the C3H/HePAS mouse strain progresses chronically and is mainly characterized by intense cardiac inflammatory lesions that recapitulate the chronic cardiac pathology observed in the human disease. Moderate striated muscle lesions are also present in C3H/HePAS mice. Viable parasites are detected and recovered from the chronic heart lesions of C3H/HePAS mice, supporting the current notion that development of heart pathology in Chagas’ disease is related to parasite persistence in the inflamed tissue. By contrast, in infected A/J mice, chronic inflammatory lesions are targeted to the liver and the skeletal muscle, while pathology and parasites are undetectable in the heart. The phenotypic analysis of F
1
(A/J × C3H/HePAS) and F
2
(A/J × C3H/HePAS) mice suggests that the genetic predisposition to develop the inflammatory lesions caused by
T. cruzi
(Sylvio X10/4 clone) is heterogeneous because the heart and liver pathology segregate in the F
2
generation. These findings raise the hypothesis that the pathology heterogeneity observed in humans with Chagas’ disease (absence and presence of cardiac or digestive chronic lesions) may be attributable to host genetic factors.
Genes ofHelicobacter pyloriRegulated by Attachment to AGS Cells
Authors: Kim Nayoung , Marcus Elizabeth A. , Wen Yi , Weeks David L. , Scott David R. , Jung Hyun Chae , Song In Sung , Sachs George
Published: March 2004

Reciprocal interactions betweenHelicobacter pyloriand cells of the gastric epithelium to which it adheres may affect colonization. Changes in gene expression ofH. pyloriinduced by adhesion to AGS gastric cancer cells by coculture were compared to changes in gene expression ofH. pyloricultured without AGS cells by using cDNA filter macroarrays. Adhesion was quantitatively verified by confocal microscopy of green fluorescent protein-expressing bacteria. Four experiments showed that 22 and 21H. pylorigenes were consistently up- and down-regulated, respectively. The up-regulated genes included pathogenicity island, motility, outer membrane protein, and translational genes. The σ28factor antagonistflgM,flgG, the stress response gene,flaA,omp11, and the superoxide dismutase gene (sodB) were down-regulated. The up-regulation ofcag3,flgB,tonB,rho, anddeaDwas confirmed by quantitative PCR, and the up-regulation oflpxD,omp6,secG,fabH, HP1285, HP0222, and HP0836 was confirmed by reverse transcription (RT)-PCR. The down-regulation offlaA,sodB, and HP0874 was confirmed by quantitative PCR, and the down-regulation ofomp11was confirmed by RT-PCR. The alteration of gene expression inH. pyloriafter adhesion to gastric cells in vitro suggests that changes in motility, outer membrane composition, and stress responses, among other changes, may be involved in gastric colonization.
Tec1p-Independent Activation of a Hypha-Associated
Candida albicans
Virulence Gene during Infection
Authors: Staib Peter , Binder Ayfer , Kretschmar Marianne , Nichterlein Thomas , Schröppel Klaus , Morschhäuser Joachim
Published: March 2004

The Tec1p transcription factor is involved in the expression of hypha-specific genes in
Candida albicans
. Although the induction of the hypha-associated
SAP5
gene by serum in vitro depends on Tec1p, deletion of all Tec1p binding site consensus sequences from the
SAP5
promoter did not affect its activation. In two different animal models of candidiasis, the
SAP5
promoter was induced even in a Δ
tec1
deletion mutant, demonstrating that the requirement for Tec1p in gene expression in
C. albicans
depends on the environmental conditions within the host.
A Deep-Rough Mutant of
Campylobacter jejuni
81-176 Is Noninvasive for Intestinal Epithelial Cells
Authors: Kanipes Margaret I. , Holder Lindsay C. , Corcoran Adrian T. , Moran Anthony P. , Guerry Patricia
Published: March 2004

A
waaF
mutant of
Campylobacter jejuni
81-176 showed decreased invasion of INT407 cells in vitro and increased sensitivity to some antibiotics compared to what was seen with the wild-type strain.
Effect of sex on preactivation of the gastrocnemius and hamstring muscles: Table 1
Authors: DeMont R G , Lephart S M
Published: March 2004

Background:The reason for the higher incidence of anterior cruciate ligament injury from non-contact mechanisms in female athletes is not known. Stability of the joint from dynamic restraints occurs through proprioceptive and kinaesthetic mechanisms providing a flexion moment. Reflexive muscle activation is different between the sexes, but it is unclear if sex differences exist in the ability to dynamically stabilise joints through a neuromuscular feed forward process as measured by preactivation of the muscles.

Objective:To determine if the level of preactivation of the gastrocnemius and hamstring muscles during dynamic activity is affected by sex.

Methods:Thirty four healthy active subjects, evenly grouped by sex, participated in the study. Maximum voluntary contraction normalised electromyographic (EMG) activity of the quadriceps, hamstrings, and gastrocnemius muscles was recorded during downhill walking (0.92 m/s) and running (2.08 m/s) on a 15° declined treadmill. Preactivation of the EMG signal was calculated by setting a mark 150 milliseconds before foot strike, as indicated by a footswitch. Multiplettests for sex differences of preactivity mean percentage (M-EMG%) during the downhill activities were performed.

Results:The female subjects had a higher M-EMG% for the medial hamstrings than the male subjects (31.73 (9.89) and 23.04 (8.59) respectively;t(2,32) =  2.732, p  =  0.01) during walking. No other muscles exhibited a sex difference in M-EMG% during either activity.

Conclusion:The female subjects in this study showed higher medial hamstring preactivation. However, this may be because they were not injured, indicating their propensity for joint stabilisation. A long term prospective study is required to eliminate this potential explanation. No sex difference in gastrocnemius preactivation was seen, adding to the controversy about whether this muscle contributes to feed forward joint stability. Further research of preactivation of the musculature of the leg is required.
Fitness levels of middle aged martial art practitioners
Authors: Douris P , Chinan A , Gomez M , Aw A , Steffens D , Weiss S
Published: March 2004

Objectives:To quantify and compare fitness levels of middle aged practitioners of soo bahk do (SBD; a Korean martial art similar to karate) with those of sedentary subjects.

Methods:Eighteen volunteers, 14 men and four women (aged 40–60 years), participated. Nine sedentary subjects (mean age 46.7 years) and nine SBD practitioners (mean age 46.8 years) were matched for sex and age. All subjects participated in a one day battery of fitness tests. The following dependent variables were tested: body composition, balance, flexibility, quadriceps strength, grip strength, muscle endurance, and aerobic capacity.

Results:All dependent variables were analysed using pairedttests. Body composition (% body fat) for the SBD group was 18.9%v30.8% for the sedentary group (p  =  0.004). The SBD group was able to balance for 61.8 secondsv26.2 seconds for the sedentary group (p  =  0.02). The result for the sit and reach flexibility test was 22.3 cm for the SBD groupv10.4 cm for the sedentary group (p  =  0.01). The number of push ups performed in one minute was 47.0 for the SBD groupv18.6 for the sedentary group (p  =  0.0003), and the number of sit ups performed was 66.1 for the SBD group and 37.3 for the sedentary group (p  =  0.00006). Aerobic capacity was 41.0 ml/kg/minv31.1 ml/kg/min for the sedentary group (p  =  0.04). Quadriceps strength was 99.5% (peak torque/body weight) v 83.0% for the sedentary group (p  =  0.02). Only grip strength was not significantly different.

Conclusions:There were significant differences between the groups for most of the physical fitness tests. The SBD practitioners displayed greater aerobic capacity, balance, flexibility, muscle endurance, and strength, and less body fat than the sedentary controls matched for age and sex. SBD can be considered an excellent form of exercise for the promotion of fitness in adults. Health professionals should be aware that there are alternative methods to traditional exercise that can increase the physical fitness and health of the middle aged population.
Massage provision by physiotherapists at major athletics events between 1987 and 1998
Authors: Galloway S D R , Watt J M
Published: March 2004

Background:The equivocal findings in the literature on efficacy of massage makes it difficult to assess the requirement for, or justify the use of, specialist massage personnel at major athletics events. However, the use of massage by athletes during training and competition remains popular.

Objectives:To quantify the amount of their time that physiotherapists devote to massage treatment at major athletics events in an attempt to determine the importance of this treatment modality, and to examine whether the use of massage at athletics events is changing over time.

Methods:Data recorded by the head team physiotherapist from 12 major athletics events (national and international events) between 1987 and 1998 were examined. For each event, the data included: total number of treatments administered by the physiotherapist, the treatment modalities used, and the number of attendances for treatment. The amount of massage provided was expressed as a percentage of the total number of treatments for each athletic event, and the pattern of change in use of massage treatment over time was evaluated.

Results:The percentage of time spent providing massage treatment ranged from 24.0% to 52.2% of the total number of treatments made. The overall median percentage of total treatments in the form of massage was 45.2%. No significant increase or decrease in the use of massage as a treatment modality was observed between 1987 and 1998 in the athletics events examined (p  =  0.95).

Conclusions:A significant proportion of physiotherapists’ time is devoted to the delivery of massage treatment at athletics events. The demand for massage treatment has been steady over the time period, in the events for which data are available, indicating a consistent use of this treatment modality. Given the popularity of massage among athletes, consideration should be given to the use of specialist sports massage staff at major athletics events. Furthermore, it would seem prudent to further investigate the efficacy of the treatment.
Acute compartment syndrome of the anterior thigh following quadriceps strain in a footballer
Authors: Burns B J , Sproule J , Smyth H
Published: March 2004

A rare case is presented of acute anterior compartment syndrome in the thigh of a footballer caused by an acute quadriceps strain, exacerbated by poor first aid and alcohol ingestion. Decompressive fasciotomy with subsequent split skin grafting of the wound defect resulted in a satisfactory outcome. The diagnosis requires a high index of suspicion lest it be overlooked with inevitably disastrous consequences.
Association between stressful life events and exacerbation in multiple sclerosis: a meta-analysis
Authors: Mohr David C , Hart Stacey L , Julian Laura , Cox Darcy , Pelletier Daniel
Published: March 2004

Objective To quantify the association between stressful life events and exacerbations of multiple sclerosis.

Data sources PubMed, PsychInfo, and Psychological Abstracts searched for empirical papers from 1965 to February 2003 with terms “stress”, “trauma”, and “multiple sclerosis”.

Review methods Three investigators independently reviewed papers for inclusion/exclusion criteria and extracted the relevant data, including methods, sample statistics, and outcomes.

Results Of 20 studies identified, 14 were included. The meta-analysis showed a significant increase in risk of exacerbation in multiple sclerosis after stressful life events, with a weighted average effect size of d = 0.53 (95% confidence interval 0.40 to 0.65), P < 0.0001. The studies were homogenous, q = 16.62, p = 0.22, i2 = 21.8%. Neither sampling nor study methods had any effect on study outcomes.

Conclusions There is a consistent association between stressful life events and subsequent exacerbation in multiple sclerosis. However these data do not allow the linking of specific stressors to exacerbations nor should they be used to infer that patients are responsible for their exacerbations. Investigation of the psychological, neuroendocrine, and immune mediators of stressful life events on exacerbation may lead to new behavioural and pharmacological strategies targeting potential links between stress and exacerbation.
CONSTRUCTION OF METASTABLE STATES IN QUANTUM ELECTRODYNAMICS
Authors: MÜCK MATTHIAS
Published: March 2004

In this paper, we construct metastable states of atoms interacting with the quantized radiation field. These states emerge from the excited bound states of the non-interacting system. We prove that these states obey an exponential time-decay law. In detail, we show that their decay is given by an exponential function in time, predicted by Fermi's Golden Rule, plus a small remainder term. The latter is proportional to the (4+β)th power of the coupling constant and decays algebraically in time. As a result, though it is small, it dominates the decay for large times. A central point of the paper is that our remainder term is significantly smaller than the one previously obtained in [1] and as a result we are able to show that the time interval during which the Fermi's Golden Rule can be observed is significantly longer that the time interval obtained in [1]. This improvement is achieved by incorporating a part of the complex dilatation resonance states into our construction of the metastable states rather than using the unperturbed eigenstates (the excited bound states of the non-interacting system). Thus, the connection to resonance states allows us to introduce metastable states which qualify better in the description of unstable excited states of the interacting system.
DISCOVERY OF THE STRANGENESS S=+1 PENTAQUARK
Authors: NAKANO TAKASHI , HICKS KENNETH
Published: March 2004

The theoretical motivation to look for S=+1 resonances is introduced and searches for such states in the literature are reviewed. The motivation for the recent pentaquark searches is discussed and the experimental details are described for several positive results of the S=+1 resonance with a mass of approximately 1.54 GeV, now called the Θ+. Finally, some new theoretical proposals to explain the recent experimental results are briefly mentioned, followed by a short discussion of future experimental prospects to learn more about pentaquark states.
MODIFIED AMBEGAOKAR–HALPERIN MODEL AND DISSIPATION IN THE POLYCRYSTALLINE Ba2YCu3O7-δ SUPERCONDUCTOR
Authors: BHALLA G. L. , PRATIMA  , MALIK AMITA
Published: March 2004

The magnetoresistance curves of polycrystalline Ba 2 YCu 3 O 7-δ samples for H=0, 1050 and 4880 G are analyzed using the modified Ambegaokar–Halperin model. The analysis shows the occurrence of a crossover in the R–T curves at a field dependent temperature T BP , revealing that the dissipation in Ba 2 YCu 3 O 7-δ samples is possibly caused by two different mechanisms: vortex-dynamics in the low temperature region (below T BP ) and the order parameter fluctuations in the high temperature region (above T BP ).
PHONON POLARITON MODES IN QUANTUM DOT SUPERLATTICES
Authors: WILSON K. S. JOSEPH , NAVANEETHAKRISHNAN K.
Published: March 2004

The phonon polariton modes in a quantum dot superlattice system are calculated, extending an earlier theory developed for quantum well and quantum well wire superlattices.14 Results are presented for the GaAs/GaP superlattice system as an example. Our findings exihibit the bulk polariton and the quantum well behaviors as limiting cases.
IMPLEMENTING THE MULTILAYER RETINAL MODEL ON THE COMPLEX-CELL CNN-UM CHIP PROTOTYPE
Authors: BÁLYA DÁVID , PETRÁS ISTVÁN , ROSKA TAMÁS , CARMONA RICARDO , VÁZQUEZ ANGEL RODRÍGUEZ
Published: March 2004

There is hardly a more important sensory modality for humans and other mammals than vision. The first and best-known part of the visual system is the retina, which is not a mere photoreceptor or static camera but a sophisticated feature preprocessor with continuous input and several parallel output channels. These interacting channels represent the visual scene. Never before has it been known in neuroscience how these channels build up a "visual language". Our mammalian retina model can generate the elements of this visual language. In the present paper the design steps of the implementation of the multilayer CNN retinal model is shown. It is rare that an analogic CNN algorithm has such a sophisticated series of different complex dynamics, meanwhile it is feasible on a recently fabricated complex cell CNN-UM chip. The mammalian retina model is decomposed into a full-custom mixed-signal chip that embeds digitally programmable analog parallel processing and distributed image memory on a common silicon substrate. The chip was designed and manufactured in a standard 0.5 μm CMOS technology and contains approximately 500,000 transistors. It consists of 1024 processing units arranged into a 32×32 grid. The functional features of the chip are in accordance with the second-order complex cell CNN-UM architecture: two CNN layers with programmable inter- and intra-layer connections between cells as well as programmable layer time constants. The uniqueness of this approach, among others, lies in the reprogrammability, i.e. the openness to any new discovery, even after a possible retinal implementation.
INDEPENDENT COMPONENT ANALYSIS SEPARATES SEQUENCE-SENSITIVE ERP COMPONENTS
Authors: JENTZSCH INES
Published: March 2004

Human performance is strongly influenced by the sequence of events. Decreasing the response-stimulus interval (RSI) between events qualitatively changes these so-called sequential effects. Using event-related brain potentials (ERPs) to detect electrical brain activity related to sequential patterns helps to uncover mechanisms underlying the observed performance data. Using a spatial compatible two-choice task ERPs were recorded from 32 electrode sites and Independent Component Analysis (ICA) applied to separate sequence-sensitive ERP components from two experiments, involving different RSIs. Independent Component Analysis was able to separate temporally and spatially overlapping ERP components. Sensitivity to the sequence of preceding events could be revealed in an early subcomponent of the N100 complex. Moreover, and in line with earlier reports sequential effects were also observed in P300 subcomponents.
BAYESIAN CLASSIFICATION OF SINGLE-TRIAL EVENT-RELATED POTENTIALS IN EEG
Authors: KOHLMORGEN JENS , BLANKERTZ BENJAMIN
Published: March 2004

We present a systematic and straightforward approach to the problem of single-trial classification of event-related potentials (ERP) in EEG. Instead of using a generic classifier off-the-shelf, like a neural network or support vector machine, our classifier design is guided by prior knowledge about the problem and statistical properties found in the data. In particular, we exploit the well-known fact that event-related drifts in EEG potentials, albeit hard to detect in a single trial, can well be observed if averaged over a sufficiently large number of trials. We propose to use the average signal and its variance as a generative model for each event class and use Bayes' decision rule for the classification of new and unlabeled data. The method is successfully applied to a data set from the NIPS*2001 Brain–Computer Interface post-workshop competition. Our result turned out to be competitive with the best result of the competition.
ATTENTION-LOCKED COMPUTATION WITH CHAOTIC NEURAL NETS
Authors: LOURENÇO CARLOS
Published: March 2004

We review a neural network model based on chaotic dynamics [Babloyantz & Lourenço, 1994, 1996] and provide a detailed discussion of its biological and computational relevance. Chaos can be viewed as a "reservoir" containing an infinite number of unstable periodic orbits. In our approach, the periodic orbits are used as coding devices. By considering a large enough number of them, one can in principle expand the information processing capacity of small or moderate-size networks. The system is most of the time in an undetermined state characterized by a chaotic attractor. Depending on the type of an external stimulus, the dynamics is stabilized into one of the available periodic orbits, and the system is then ready to process information. This corresponds to the system being driven into an "attentive" state. We show that, apart from static pattern processing, the model is capable of dealing with moving stimuli. We especially consider in this paper the case of transient visual stimuli, which has a clear biological relevance. The advantages of chaos over more regular regimes are discussed.
ENTROPY AND COMPLEXITY ANALYSIS OF INTRACRANIALLY RECORDED EEG
Authors: STEUER R. , EBELING W. , BENGNER T. , DEHNICKE C. , HÄTTIG H. , MEENCKE H.-J.
Published: March 2004

We present an entropy and complexity analysis of intracranially recorded EEG from patients suffering from a left frontal lobe epilepsy. Our approach is based on symbolic dynamics and Shannon entropy. In particular, we will discuss the possibility to monitor long-term dynamical changes in brain electrical activity. This might offer an alternative approach for the analysis and more fundamental understanding of human epilepsies.
PHOTOCATALYTIC CONVERSION OF METHANE INTO METHANOL OVER THE MoO3(010) SURFACE USING A SIMULATION METHOD
Authors: MOSHFEGH A. Z. , DASHTI M.
Published: March 2004

In this investigation, we have studied the kinetics and mechanism of photocatalytic conversion of methane into methanol reaction over the MoO 3(010) surface using a computer simulation method. Methane and oxygen as the reactants are used at room temperature and atmospheric pressure under UV photoirradiation of the catalyst. According to our data analysis, the order of methanol formation reaction with respect to CH 4 and O 2 was determined to be l=0.30 and m=-1.03, respectively. The highest methanol formation rate (TOF) value was obtained at about 0.05 molecule/s.site in a range of 25–35 W/cm2 incident light intensity with energy hν≥Eg. The selectivity of CH 3 OH was increased with increasing partial pressure of CH 4, while the selectivity of CHOH was decreased. The effect of light intensity on the CH 3 OH selectivity was also studied under different P CH 4/P O 2 ratios, namely 0.9, 1.5 and 2.6. The highest CH 3 OH selectivity was obtained at 1.5 ratio.
SOME ALGORITHMS FOR CURVE DESIGN AND AUTOMATIC OUTLINE CAPTURING OF IMAGES
Authors: SARFRAZ MUHAMMAD
Published: March 2004

A new multipurpose curve technique has been introduced which is meant to automatically provide a fit to any ordered data in a plane. The technique is particularly economical for designing purposes as well as for the visualization of a large amount of data sets. A more flexible class of cubic functions is the basis of this technique. This class of functions involves two control parameters, to produce more flexible shapes than ordinary Bézier cubics or Hermite cubics, in each segment. These functions, together with the control parameters, are utilized to fit a design curve in an interactive way. These functions are also utilized in an optimal way to fit a design curve to the data arose from any image or a scientific phenomenon. The design curve method is highly useful to capture the outlines of images. It differs, in its methodology, from the existing techniques in the literature using Bézier cubics. The curve technique has used various ideas in its construction. These ideas include end-point interpolation, detection of characteristic points, least squares approximation. The final shape is achieved by stitching the generalized Bézier cubic pieces with GC1 smoothness. Finally, three algorithms have been proposed for various applications.
Insulin suppresses PDK-4 expression in skeletal muscle independently of plasma FFA
Authors: Lee Felix N. , Zhang Lihua , Zheng Dan , Choi Woo S. , Youn Jang H.
Published: March 2004

Starvation and experimental diabetes induce a stable increase in pyruvate dehydrogenase kinase (PDK) activity in skeletal muscle, which is largely due to a selective upregulation of PDK-4 expression. Increased free fatty acid (FFA) level has been suggested to be responsible for the upregulation. Because these metabolic states are also characterized by insulin deficiency, the present study was designed to examine whether insulin has a significant effect to regulate PDK mRNA expression in rat skeletal muscle. In study 1, overnight-fasted rats received an infusion of saline or insulin for 5 h ( n = 6 each). During the insulin infusion, plasma glucose was clamped at basal levels (euglycemic hyperinsulinemic clamp). A third group ( n = 6) received Intralipid infusion during the clamp to prevent a fall in plasma FFA. PDK-2 mRNA level in gastrocnemius muscle was not altered by insulin or FFA (i.e., Intralipid infusion). In contrast, PDK-4 mRNA level was decreased 72% by insulin ( P < 0.05), and Intralipid infusion prevented only 20% of the decrease. PDK-4 protein level was decreased ∼20% by insulin ( P < 0.05), but this effect was not altered by Intralipid infusion. In study 2, overnight-fasted rats were refed or received an infusion of saline or nicotinic acid (NA, 30 μmol/h) for 5 h ( n = 5 each). During the refeeding and NA infusion, plasma FFA levels were similarly (i.e., 60–70% vs. saline control) lowered. Muscle PDK-4 mRNA level decreased 77% after the refeeding ( P < 0.05) but not after the NA infusion. In conclusion, the present data indicate that insulin had a profound effect to suppress PDK-4 expression in skeletal muscle and that, contrary to previous suggestions, circulating FFA had little impact on PDK-4 mRNA expression, at least within 5 h.
VEGF causes pulmonary hemorrhage, hemosiderosis, and air space enlargement in neonatal mice
Authors: Le Cras T. D. , Spitzmiller R. E. , Albertine K. H. , Greenberg J. M. , Whitsett J. A. , Akeson A. L.
Published: March 2004

To determine whether increased levels of VEGF disrupt postnatal lung formation or function, conditional transgenic mice in which VEGF 164 expression was enhanced in respiratory epithelial cells were produced. VEGF expression was induced in the lungs of VEGF transgenic pups with doxycycline from postnatal day 1 through 2 and 6 wk of age. VEGF levels were higher in bronchoalveolar lavage fluid (BALF) and lung homogenates of VEGF transgenic mice compared with endogenous VEGF levels in controls. Neonatal mortality was increased by 50% in VEGF transgenic mice. Total protein content in BALF was elevated in VEGF transgenic mice. Surfactant protein B protein expression was unaltered in VEGF transgenic mice. Although postnatal alveolar and vascular development were not disrupted by VEGF expression, VEGF transgenic mice developed pulmonary hemorrhage, alveolar remodeling, and macrophage accumulation as early as 2 wk of age. Electron microscopy demonstrated abnormal alveolar capillary endothelium in the VEGF transgenic mice. In many locations, the endothelium was discontinuous with segments of attenuated endothelial cells. Large numbers of hemosiderin-laden macrophages and varying degrees of emphysema were observed in adult VEGF transgenic mice. Overexpression of VEGF in the neonatal lung increased infant mortality and caused pulmonary hemorrhage, hemosiderosis, alveolar remodeling, and inflammation.
A mapping study of cardiorespiratory responses to chemical stimulation of the midline medulla oblongata in ventilated and freely breathing rats
Authors: Verner Todd A. , Goodchild Ann K. , Pilowsky Paul M.
Published: March 2004

The aim of this study was to examine the cardiorespiratory effects of chemically stimulating neurons in the midline medulla oblongata (MM) of artificially ventilated and freely breathing anesthetized rats. Earlier studies reported that stimulation of the MM elicits increases or decreases in mean arterial pressure (MAP) and phrenic nerve activity, depending on the mode and site of stimulation, anesthetic, and species. In the first series of experiments, rats were anesthetized with urethane, artificially ventilated, paralyzed, and bilaterally vagotomized. The rostrocaudal extent of the MM was mapped by microinjections of dl-homocysteic acid or l-glutamate (both 100 mM, 100 nl), and, in line with previous studies, most injections produced only small responses in MAP, heart rate, and splanchnic sympathetic nerve activity. Increases in respiratory parameters were evoked in caudal regions. However, activation of a discrete region of the MM at the level of the caudal pole of the facial nucleus (CP7) consistently caused a dramatic reduction in phrenic nerve amplitude and/or frequency and, in six rats, produced a prolonged apnea. The second series of experiments was carried out on freely breathing pentobarbitone sodium-anesthetized rats, with a diaphragmatic electromyogram used to monitor respiratory activity. Respiratory activity could again be abolished at CP7 after microinjections of glutamate (100 mM, 50 nl); however, these responses were accompanied by large decreases in MAP and moderate reductions in heart rate. This depression of respiratory activity may be due to activation of propriobulbar inhibitory neurons that project to known respiratory centers in the brain stem.
Effects of Ca2+ channel antagonists on acetylcholine and catecholamine releases in the in vivo rat adrenal medulla
Authors: Akiyama Tsuyoshi , Yamazaki Toji , Mori Hidezo , Sunagawa Kenji
Published: March 2004

To elucidate the types of voltage-dependent Ca2+ channels controlling ACh and catecholamine releases in the in vivo adrenal medulla, we implanted microdialysis probes in the left adrenal medulla of anesthetized rats and investigated the effects of Ca2+ channel antagonists on ACh, norepinephrine, and epinephrine releases induced by nerve stimulation. The dialysis probes were perfused with Ringer solution containing a cholinesterase inhibitor, neostigmine. The left splanchnic nerves were electrically stimulated at 2 and 4 Hz before and after intravenous administration of Ca2+ channel antagonists. ω-Conotoxin GVIA (an N-type Ca2+ channel antagonist, 10 μg/kg) inhibited ACh release at 2 and 4 Hz by ∼40%, norepinephrine release at 4 Hz by ∼50%, and epinephrine release at 2 and 4 Hz by ∼45%. A fivefold higher dose of ω-conotoxin GVIA (50 μg/kg) did not further inhibit these releases. ω-Conotoxin MVIIC (a P/Q-type Ca2+ channel antagonist, 50 μg/kg) inhibited ACh and epinephrine releases at 4 Hz by ∼30%. Combined ω-conotoxin GVIA (50 μg/kg) and MVIIC (250 μg/kg) inhibited ACh release at 2 and 4 Hz by ∼70% and norepinephrine and epinephrine releases at 2 and 4 Hz by ∼80%. Nifedipine (an L-type Ca2+ channel antagonist, 300 and 900 μg/kg) did not change ACh release at 2 and 4 Hz; however, nifedipine (300 μg/kg) inhibited epinephrine release at 4 Hz by 20%, and nifedipine (900 μg/kg) inhibited norepinephrine and epinephrine releases at 4 Hz by 30%. In conclusion, both N- and P/Q-type Ca2+ channels control ACh release on preganglionic splanchnic nerve endings while L-type Ca2+ channels do not. L-type Ca2+ channels are involved in norepinephrine and epinephrine releases on chromaffin cells.
Observer-rated ataxia: rating scales for assessment of genetic differences in ethanol-induced intoxication in mice
Authors: Metten Pamela , Best Karyn L. , Cameron Andy J. , Saultz Alisha B. , Zuraw Jessica M. , Yu Chia-Hua , Wahlsten Douglas , Crabbe John C.
Published: March 2004

Identification of genetic and physiological mechanisms underlying a drug's or mutation's effects on motor performance could be aided by the existence of a simple observation-based rating scale of ataxia for mice. Rating scales were developed to assess ataxia after ethanol (2.75, 3.0, and 3.25 g/kg) in nine inbred mouse strains. Each scale independently rates a single behavior. Raters, blinded to dose, scored four behaviors (splay of hind legs, wobbling, nose down, and belly drag) at each of four time points after injection. The severities of hind leg splaying and wobbling were quantifiable, whereas nose down and belly dragging were expressed in all-or-none fashion. Interrater reliabilities were substantial (0.75 ≤ r ≤ 0.99). Splay scores (rated 0–5) displayed significant effects of strain, dose, and time point. Wobbling (rated 0–4) was dependent on strain and time point. Ethanol affected wobbling (most strains scored >0 at some time), but all doses were equally effective. Incidence of nose down and belly dragging behaviors increased strain dependently after ethanol, but strains did not differentially respond to dose. Ethanol-induced splaying was modestly, and negatively, genetically correlated with wobbling. Nose down and belly dragging tended to be associated with splaying and wobbling at later times. Four distinct ataxia-related behaviors were sensitive to ethanol. Strains differed in ethanol sensitivity for all measures. Modest strain mean correlations among behaviors indicate that these behaviors are probably under control of largely different genes and that ataxia rating scales should rate separate behaviors on discrete scales.