bluuebunny/crossref_metadata_2025 huggingface dataset:
Does caloric restriction extend life in wild mice?
Authors: Harper James M. , Leathers Charles W. , Austad Steven N.
Published: October 2006

To investigate whether mice genetically unaltered by many generations of laboratory selection exhibit similar hormonal and demographic responses to caloric restriction (CR) as laboratory rodents, we performed CR on cohorts of genetically heterogeneous male mice which were grandoffspring of wild‐caught ancestors. Although hormonal changes, specifically an increase in corticosterone and decrease in testosterone, mimicked those seen in laboratory‐adapted rodents, we found no difference in mean longevity between ad libitum (AL) and CR dietary groups, although a maximum likelihood fitted Gompertz mortality model indicated a significantly shallower slope and higher intercept for the CR group. This result was due to higher mortality in CR animals early in life, but lower mortality late in life. A subset of animals may have exhibited the standard demographic response to CR in that the longest‐lived 8.1% of our animals were all from the CR group. Despite the lack of a robust mean longevity difference between groups, we did note a strong anticancer effect of CR as seen in laboratory rodents. Three plausible interpretations of our results are the following: (1) animals not selected under laboratory conditions do not show the typical CR effect; (2) because wild‐derived animals eat less when fed AL, our restriction regime was too severe to see the CR effect; or (3) there is genetic variation for the CR effect in wild populations; variants that respond to CR with extended life are inadvertently selected for under conditions of laboratory domestication.
A Review of Psychological Models and Interventions for Medically Unexplained Somatic Symptoms in Children
Authors: Husain Kaneez , Browne Tess , Chalder Trudie
Published: October 2006

The aim of this review is to outline the various psychological models of medically unexplained somatic symptoms in children and the interventions derived from these. The interventions that have been evaluated in randomised controlled trials are reviewed, and the implications of the findings for the models are described.
Unmet Mental Health Service Needs Among Norwegian Children and Adolescents
Authors: Andersson Helle Wessel , Ose Solveig Osborg
Published: October 2006

Background:  The Norwegian 10 year mental health plan identifies important roles for public health nurses in the early identification, care and referral of children and adolescents with mental health problems. This study aims to identify the extent to which public health nurses are meeting these needs.

Method:  Over a 4 week period the mental health needs of 3065 children who were seen by publich health nurses were identified.

Results:  Achieving the ongoing Norwegian mental health plan may require better access to trained professionals in the public health sector, further expansion of specialised mental health services, and efforts to improve inter‐agency collaboration.
Vitamin D Status in Children with Intractable Epilepsy, and Impact of the Ketogenic Diet
Authors: Bergqvist A.G. Christina , Schall Joan I. , Stallings Virginia A.
Published: October 2006

Summary:  Purpose: The aim of this study was to describe vitamin D status in children with intractable epilepsy prescribed newer antiepileptic drugs (AEDs) before initiation of and during 15‐month treatment with the ketogenic diet (KD).

Methods: Serum vitamin D (25‐OHD and 1,25‐OHD) and parathyroid hormone (PTH) were assessed in prepubertal children with intractable epilepsy before initiation of and during KD therapy. Three‐day weighed dietary records including KD and vitamin and mineral supplementation were obtained at baseline and at 1 month.

Results: Forty‐five children (aged 5.1 ± 2.7 years) were enrolled. Before KD therapy, 4% had deficient and 51% had insufficient serum 25‐OHD levels. Vitamin D intake was less than recommended in 47%. Adequate vitamin D intake, fewer AEDs, and generalized seizures were associated with higher serum 25‐OHD levels (p < 0.01). After 3 months on the KD, 25‐OHD levels increased (p < 0.001), and PTH declined (p < 0.001). Over the next 12‐month period, 25‐OHD levels steadily declined (p < 0.001), and PTH did not significantly change.

Conclusions: Children with intractable epilepsy treated with newer AEDs had poor vitamin D status. Their status improved over the first 3 months of KD therapy with vitamin D supplementation and slowly declined thereafter.
Prolonged Focal Negative Motor Seizures: A Video‐EEG Study
Authors: Villani Flavio , D'Amico Domenico , Pincherle Alessandro , Tullo Vincenzo , Chiapparini Luisa , Bussone Gennaro
Published: October 2006

Summary:  Purpose: Focal negative motor (akinetic) seizures are rare ictal events that are diagnostically challenging because they are difficult to differentiate from postictal Todd paresis, transient ischemic attacks, migraine events, and psychogenic episodes.

Methods: We describe a 45‐year‐old man in whom, after surgical drainage of a right frontoparietal subdural hematoma, prolonged episodes developed with flaccid paralysis of the left arm.

Results: A video‐EEG recording demonstrated a close relation between the focal motor impairment and a clear‐cut epileptic ictal discharge involving the right perirolandic cortical areas.

Conclusions: On the basis of the electroclinical data, we hypothesize the involvement of the primary motor area in the genesis of the epileptic discharge triggering focal negative seizures.
Influence of Major Antiepileptic Drugs on Attention, Reaction Time, and Speed of Information Processing: Results from a Randomized, Double‐blind, Placebo‐controlled Withdrawal Study of Seizure‐free Epilepsy Patients Receiving Monotherapy
Authors: Hessen Erik , Lossius Morten I. , Reinvang Ivar , Gjerstad Leif
Published: October 2006

Summary:  Purpose: All major antiepileptic drugs (AEDs) have been reported to be associated with cognitive side effects. Uncertainty exists regarding the degree of cognitive effects, primarily because many studies do not adhere to basic standards of methodology and design. The aim of this study was to assess the effect of discontinuation of AEDs in patients receiving monotherapy on measures of attention, reaction time, and speed of information processing.

Methods: The 150 subjects who had been seizure free >2 years on drug monotherapy went through a randomized, double‐blind, placebo‐controlled study. Each patient was included for 12 months or until seizure relapse. Cognitive function was assessed with the California Computerized Assessment Package at baseline and 7 months after discontinuation.

Results: The major finding in this study is that discontinuation of major AEDs significantly improved performance on tests that require complex cognitive processing under time pressure. The difference in speed of cognitive processing between the two groups on these tasks was between 24 to 43 ms. Simple tasks of attention and reaction time revealed no significant differences between the discontinuation group and the nondiscontinuation group. Most of the subjects in the study were medicated with carbamazepine (CBZ) and valproate (VPA). The outcome of discontinuation of CBZ was similar to the outcome for the total study population, whereas withdrawal of VPA revealed only a nonsignificant tendency in the same direction.

Conclusions: The results suggest that seizure‐free epilepsy patients receiving monotherapy can obtain improvement in cognitive function if they discontinue AED treatment.
Interictal Depression, Anxiety, Personality Traits, and Psychological Dissociation in Patients with Temporal Lobe Epilepsy (TLE) and Extra‐TLE
Authors: Swinkels Wilhelmina A.M. , Van Emde Boas Walter , Kuyk Jarl , Van Dyck Richard , Spinhoven Philip
Published: October 2006

Summary:  Purpose: This study was performed to investigate the relation between symptoms of interictal depression, anxiety, personality traits, and psychological dissociation with the localization and lateralization of the epileptogenic zone in patients with partial epilepsy.

Methods: All patients were diagnosed according to the localization‐related concept of the 1989 International League Against Epilepsy (ILAE) Classification of Epilepsies and Epileptic Syndromes, and the localization and lateralization of the epileptogenic zone was established by using the clinical criteria for noninvasive presurgical evaluation. This resulted in 67 patients with temporal lobe epilepsy (TLE) and 64 patients with extra‐TLE. All patients were assessed on the various aspects of psychopathology by using a comprehensive battery of standardized diagnostic instruments.

Results: We did not find the hypothesized excess of psychiatric symptoms in patients with (mesial) TLE in comparison with patients with extra‐TLE. We also found no differences between patients with the lateralization of epilepsy in the left versus the right hemisphere.

Conclusions: TLE per se cannot be considered a risk factor in developing more or more severe symptoms of psychopathology in patients with partial epilepsy. Concomitant factors, such as the duration of epilepsy, seizure frequency, and frontal lobe dysfunction may play an additional role. Our findings support the hypothesis of a multifactorial explanation for the psychiatric symptoms in patients with epilepsy.
Organizing for Radical Innovation: An Exploratory Study of the Structural Aspects of RI Management Systems in Large Established Firms
Authors: O'Connor Gina Colarelli , DeMartino Richard
Published: October 2006

To escape the intense competition of today's global economy, large established organizations seek growth options beyond conventional new product development that leads to incremental changes in current product lines. Radical innovation (RI) is one such pathway, which results in organically driven growth through the creation of whole new lines of business that bring new to the world performance features to the market and may result in the creation of entirely new markets. Yet success is elusive, as many have experienced and scholars have documented. This article reports results of a three‐year, longitudinal study of 12 large established firms that have declared a strategic intent to evolve their RI capabilities. In contrast to other academic research that has analyzed specific projects to understand management practices appropriate for RI, the present research reported explores the evolution of management systems for enabling radical innovation to occur repeatedly in large firms and reports on one aspect of this management system: organizational structures for enabling and nurturing RI. To consider organizational structure as a venue for capability development is new in the management of innovation and dynamic capabilities literatures. Conventional wisdom holds that RIs should be incubated outside the company and assimilated once they have gained traction in the marketplace. Numerous experiments with organizational structures were observed that instead work to manage the interfaces between the RI management system and the mother organization. These structures are described here, and insights are drawn out regarding radical innovation competency requirements, transition challenges, senior leadership mandates, and business‐unit ambidexterity. The centerpiece of this research is the explication of the Discovery–Incubation–Acceleration framework, which details three sets of necessary, though not sufficient competencies, for building an RI capability.
Dynamic Stabilization: Structural Plasticity at Inhibitory Postsynaptic Sites
Authors: Kneussel Matthias
Published: October 2006

Rearrangement of molecular structures at individual synapses can contribute to network plasticity. At mossy fiber presynaptic terminals, experience regulates both connectivity and structure of individual boutons. Moreover, dendritic spines and postsynaptic densities of glutamatergic synapses rapidly form and remodel in an activity‐dependent manner. Recent studies of the postsynaptic scaffold molecule gephyrin have now revealed that also inhibitory shaft synapses undergo rapid remodeling at the postsynaptic scaffold level. Taking into account that also surface membrane receptors are highly mobile, local coincidence of receptors and scaffold elements in adjacent layers at dendritic shafts might depend on regulatory processes underlying synaptic plasticity.
Use of Fluorescein as a Ground Water Tracer in Brackish Water Aquifers
Authors: Chua Lloyd H.C. , Robertson Alexander P. , Yee W.K. , Shuy E.B. , Lo Edmond Y.M. , Lim T.T. , Tan S.K.
Published: October 2006

A drift and pumpback experiment was conducted in a brackish water sandfill. The sandfill was reclaimed from the sea in the eastern part of Singapore and contains sands with low organic and clay/silt contents. The high salinity in the ground water precludes the use of chloride and bromide as tracers in such an environment, and a field experiment was conducted to assess the viability of using fluorescein as a tracer in brackish water aquifers. Nitrate was used as a second tracer to serve as a check. Initial laboratory studies showed that fluorescence was unaffected over the range of electrical conductivity and pH of the ground water. Results from the field experiment show that fluorescein appears to behave conservatively.
Reduced pH and contractility in failing rat cardiomyocytes
Authors: Kemi O. J. , Arbo I. , Høydal M. A. , Loennechen J. P. , Wisløff U. , Smith G. L. , Ellingsen Ø.
Published: October 2006

Aim:  To determine whether reduced cardiomyocyte contractility in heart failure is associated with reduced intracellular pH (pHi). Involvement of the Na+/H+ exchanger and the H+/K+ ATPase were investigated with specific blockers.

Methods:  Myocardial infarction and subsequent heart failure in Sprague–Dawley rats were induced by chronic occlusion of the left coronary artery. 6 weeks post‐ligation, contractility (cell shortening) and pHi (BCECF fluorescence) were recorded in freshly dissociated cardiomyocytes during 2–10 Hz electrical stimulation, with or without either Na+/H+ exchanger or H+/K+ ATPase inhibition.

Results:  Elevated end‐diastolic and reduced peak systolic pressures confirmed heart failure. Increased heart weights (20–30%; P ≤ 0.01) and cardiomyocyte lengths and widths (22–25%; P ≤ 0.01) confirmed substantial cardiac hypertrophy. In myocytes isolated from sham operated rats, a positive staircase response occurred with stimulation rates from 2 to 7 Hz; further increases in stimulation rate up to 10 Hz reduced contractility. In contrast, pHi fell progressively over the entire stimulation range. In failing myocytes, pHi was consistently 0.07 pH units lower and contractility 40% lower (P ≤ 0.01) than sham control values; the shape of the contractility staircase remained similar to controls. At all stimulation frequencies, Na+/H+ exchanger inhibition reduced pHi by 0.05 pH units (P ≤ 0.01) and contractility by 22% (P ≤ 0.05) in cardiomyocytes from the heart failure group. A significantly smaller decrease of pHi and reduction in contractility was observed after inhibition of Na+/H+ exchanger (10 μm HOE694) in sham myocytes. H+/K+ ATPase inhibition (100 μm SCH28080) had no effect on pHi.

Conclusion:  Reduced pHi is accompanied by reduced cardiomyocyte contractility in isolated myocytes from post‐MI heart failure. The data suggest compensatory Na+/H+ exchanger activation in heart failure, whereas H+/K+ ATPase does not appear to contribute significantly to pHi maintenance.
Different effect of ATP on ANP receptor guanylyl cyclase in spontaneously hypertensive and normotensive rats
Authors: Woodard G. E. , Zhao J. , Rosado J. A.
Published: October 2006

Aim:  Natriuretic peptide receptor A (NPR‐A) is the main physiological receptor for atrial natriuretic peptide (ANP). Maximal activation of NPR‐A guanylyl cyclase (GC) requires ANP binding and ATP interaction with a putative cytoplasmic site. This study investigates the regulatory effect of ATP on GC‐coupled NPR‐A activity in Wistar Kyoto (WKY) and spontaneously hypertensive rats (SHR).

Methods:  Cyclic GMP production and competitive inhibition of [125I]ANP1−28 binding were performed in solubilized glomerular and papillary renal membranes.

Results:  Here, we report that incubation of renal glomerular and papillary membranes with ATP induced a concentration‐dependent increase in basal and ANP1−28‐stimulated GC activity that was significantly greater in SHR than in age‐matched WKY. ATPγS was more effective than ATP and induced a greater stimulation of cGMP production in SHR than in WKY. In contrast, in solubilized membranes ATP exerted an inhibitory role on basal and ANP1−28‐induced GC activity, suggesting that an accessory protein is required for ATP‐induced GC activation. ATP increases NPR‐A affinity for ANP1−28 and decreased Bmax in crude and solubilized membranes. Kinetic analysis of GC‐coupled NPR‐A revealed that ATP reduced the Km and increased the Vmax, an effect that was greater in SHR.

Conclusion:  Our observations indicate that ATP exerts a greater net effect on NPR‐A in SHR than in WKY, which might explain the greater rate of cGMP production observed in SHR compared to WKY.
Experimental Analysis of Thick Blunt Trailing-Edge Wind Turbine Airfoils
Authors: Baker J. P. , Mayda E. A. , van Dam C. P.
Published: October 2006

An experimental investigation of blunt trailing-edge or flatback airfoils was conducted in the University of California, Davis aeronautical wind tunnel. The blunt trailing-edge airfoil is created by symmetrically adding thickness to both sides of the camber line of the FB-3500 airfoil, while maintaining the maximum thickness-to-chord ratio of 35%. Three airfoils of various trailing-edge thicknesses (0.5%, 8.75%, and 17.5% chord) are discussed in this paper. In the present study, each airfoil was tested under free and fixed boundary layer transition flow conditions at Reynolds numbers of 333,000 and 666,000. The fixed transition conditions were used to simulate surface soiling effects by placing artificial tripping devices at 2% chord on the suction surface and 5% chord on the pressure surface of each airfoil. The results of this investigation show that lift increases and the well-documented thick airfoil sensitivity to leading-edge transition reduces with increasing trailing-edge thickness. The flatback airfoils yield increased drag coefficients over the sharp trailing-edge airfoil due to an increase in base drag. The experimental results are compared against numerical predictions obtained with two different computational aerodynamics methods. Computations at bounded and unbounded conditions are used to quantify the wind tunnel wall corrections for the wind tunnel tests.
Symmetry Considerations When Using Proper Orthogonal Decomposition for Predicting Wind Turbine Yaw Loads
Authors: Saranyasoontorn Korn , Manuel Lance
Published: October 2006

In an earlier study, the authors discussed the efficiency of low-dimensional representations of inflow turbulence random fields in predicting statistics of wind turbine loads that included blade and tower bending moments. Both root-mean-square and 10-min extreme statistics for these loads were approximated very well when time-domain simulations were carried out on a 600kW two-bladed turbine and only a limited number of inflow “modes” were employed using proper orthogonal decomposition (POD). Here, turbine yaw loads are considered and the conventional ordering of POD modes is seen to be not as efficient in predicting full-field load statistics for the same turbine. Based on symmetry arguments, reasons for a different treatment of yaw loads are presented and reasons for observed deviation from the expected monotonic convergence to full-field load statistics with increasing POD mode number are illustrated.
Testing State-Space Controls for the Controls Advanced Research Turbine
Authors: Wright Alan D. , Fingersh Lee J. , Balas Mark J.
Published: October 2006

Control can improve wind turbine performance by enhancing energy capture and reducing dynamic loads. At the National Renewable Energy Laboratory, we are implementing and testing state-space controls on the controls advanced research turbine (CART), a turbine specifically configured to test advanced controls. We show the design of control systems to regulate turbine speed in region 3 using rotor collective pitch and reduce dynamic loads in regions 2 and 3 using generator torque. These controls enhance damping in the first drive train torsion mode. We base these designs on sensors typically used in commercial turbines. We evaluate the performance of these controls by showing field test results. We also compare results from these modern controllers to results from a baseline controller for the CART. Finally, we report conclusions to this work and outline future studies.
Experimental Determination of Geometric Parameters for an Annular Injection Type Supersonic Ejector
Authors: Kim Sehoon , Kwon Sejin
Published: October 2006

The effects of four geometric parameters of an annular injection supersonic ejector, namely, the primary nozzle exit-to-throat area ratio, the contraction angle of the mixing chamber, the cross-sectional area and L/D ratio of the second-throat on the performance parameters including the secondary flow pressure, the starting pressure and unstarting pressure were investigated experimentally. The starting pressure exhibits linearly proportional dependence on the throat area ratio when the mixing chamber length is less than a certain critical value. For a longer mixing chamber, the starting pressure is proportional to the mixing chamber length while the unstarting pressure depends on the throat area ratio only. The geometric parameters of the second-throat do not affect the static pressure of the secondary flow. This implies that the secondary flow is aerodynamically choked in the mixing chamber and the static pressure of the secondary flow is determined by the choking condition since the mixing chamber of the annular injection ejector is relatively long. Based on the findings by the experiment, a simplified analytical model was proposed to predict the secondary flow pressure. The predicted secondary flow pressure agrees reasonably well with the measurement for a small contraction angle of the mixing chamber.
An Advanced Numerical Model for Single Straight Tube Coriolis Flowmeters
Authors: Wang Tao , Baker Roger C. , Hussain Yousif
Published: October 2006

A detailed numerical model has been developed to simulate the single straight tube Coriolis flowmeter, which includes all important practical features. The measuring tube is modeled as fluid-tube interaction elements characterized as mass, stiffness, and damping matrices based on the theories of fluid-structure interaction and finite element method. Other features, such as the inner and outer cases and the driver spring, are modeled as standard ANSYS beam and shell elements and coupled to the measuring tube. The modal frequency and sensitivity factor from experiments are used to validate the model. In particular, our results show that the modal behaviour of the meter can only be adequately modeled if these practical features are included.
Thermocapillary Instabilities of Low Prandtl Number Fluid in a Laterally Heated Vertical Cylinder
Authors: Xu B. , Ai X. , Li B. Q.
Published: October 2006

Stabilities of surface-tension-driven convection in an open cylinder are investigated numerically. The cylinder is heated laterally through its sidewall and is cooled at free surface by radiation. A seeding crystal at constant temperature is in contact with the free surface. Axisymmetric base flow is solved using the high-order finite difference method. Three-dimensional perturbation is applied to the obtained base flow to determine the critical Marangoni numbers at which the axisymmetry is broken. The eigenvalue matrix equation is solved using linear fractional transformation with banded matrix structure taken into account. Critical Marangoni-Reynolds numbers are obtained at various boundary conditions.
A Quasi-Generalized-Coordinate Approach for Numerical Simulation of Complex Flows
Authors: You Donghyun , Wang Meng , Mittal Rajat , Moin Parviz
Published: October 2006

A novel structured grid approach which provides an efficient way of treating a class of complex geometries is proposed. The incompressible Navier-Stokes equations are formulated in a two-dimensional, generalized curvilinear coordinate system complemented by a third quasi-curvilinear coordinate. By keeping all two-dimensional planes defined by constant third coordinate values parallel to one another, the proposed approach significantly reduces the memory requirement in fully three-dimensional geometries, and makes the computation more cost effective. The formulation can be easily adapted to an existing flow solver based on a two-dimensional generalized coordinate system coupled with a Cartesian third direction, with only a small increase in computational cost. The feasibility and efficiency of the present method have been assessed in a simulation of flow over a tapered cylinder.
A Variant of the
HTRA1
Gene Increases Susceptibility to Age-Related Macular Degeneration
Authors: Yang Zhenglin , Camp Nicola J. , Sun Hui , Tong Zongzhong , Gibbs Daniel , Cameron D. Joshua , Chen Haoyu , Zhao Yu , Pearson Erik , Li Xi , Chien Jeremy , DeWan Andrew , Harmon Jennifer , Bernstein Paul S. , Shridhar Viji , Zabriskie Norman A. , Hoh Josephine , Howes Kimberly , Zhang Kang
Published: October 2006

Age-related macular degeneration (AMD) is the most common cause of irreversible vision loss in the developed world and has a strong genetic predisposition. A locus at human chromosome 10q26 affects the risk of AMD, but the precise gene(s) have not been identified. We genotyped 581 AMD cases and 309 normal controls in a Caucasian cohort in Utah. We demonstrate that a single-nucleotide polymorphism, rs11200638, in the promoter region of
HTRA1
is the most likely causal variant for AMD at 10q26 and is estimated to confer a population attributable risk of 49.3%. The
HTRA1
gene encodes a secreted serine protease. Preliminary analysis of lymphocytes and retinal pigment epithelium from four AMD patients revealed that the risk allele was associated with elevated expression levels of
HTRA1
mRNA and protein. We also found that drusen in the eyes of AMD patients were strongly immunolabeled with HTRA1 antibody. Together, these findings support a key role for HTRA1 in AMD susceptibility and identify a potential new pathway for AMD pathogenesis.
Regulation of
Mycobacterium tuberculosis whiB3
in the Mouse Lung and Macrophages
Authors: Banaiee N. , Jacobs W. R. , Ernst J. D.
Published: October 2006

Mycobacterium tuberculosis
is a highly successful human pathogen, with ∼2 × 10
9
individuals infected globally. To understand the responses of
M. tuberculosis
to the in vivo environment, we studied the in vivo regulation of
M. tuberculosis
genes whose
M. marinum
homologs are induced in chronically infected frog tissues. The expression of 16S rRNA was shown to remain constant in
M. tuberculosis
under in vivo and in vitro conditions and therefore could be used for internal normalization in quantitative reverse transcription-PCR assays. We found
whiB3
, a putative transcriptional regulator implicated in mediating tissue damage, to be maximally induced at 2 weeks postinfection in the lungs of wild-type and immunodeficient (gamma interferon receptor
−/−
, Rag1
−/−
, and tumor necrosis factor alpha
−/−
) mice. At later time points in wild-type mice,
whiB3
induction was decreased and gradually declined over the course of infection. In immunodeficient mice,
whiB3
induction declined rapidly and was completely abolished in moribund animals.
whiB3
was also found to be induced in naïve bone marrow-derived macrophages after 6 h of infection.
whiB3
expression in vivo and in vitro was found to be inversely correlated with bacterial density. These results indicate that
M. tuberculosis
regulates the expression of
whiB3
in response to environmental signals present in vivo and are consistent with a model of regulation by quorum sensing.
Transgenic Cows That Produce Recombinant Human Lactoferrin in Milk Are Not Protected from Experimental
Escherichia coli
Intramammary Infection
Authors: Hyvönen P. , Suojala L. , Orro T. , Haaranen J. , Simola O. , Røntved C. , Pyörälä S.
Published: October 2006

This is the first study describing an experimental mastitis model using transgenic cows expressing recombinant human lactoferrin (rhLf) in their milk. The aim of the study was to investigate the concentrations in milk and protective effects of bovine and recombinant human lactoferrin in experimental
Escherichia coli
mastitis. Experimental intramammary infection was induced in one udder quarter of seven first-lactating rhLf-transgenic cows and six normal cows, using an
E. coli
strain isolated from cows with clinical mastitis and known to be susceptible to Lf in vitro. Clinical signs were recorded during the experimental period, concentrations of human and bovine Lf and indicators of inflammation and bacterial counts were determined for milk, and concentrations of acute-phase proteins and tumor necrosis factor alpha were determined for sera and milk. Serum cortisol and blood hematological and biochemical parameters were also determined. Expression levels of rhLf in the milk of transgenic cows remained constant throughout the experiment (mean, 2.9 mg/ml). The high Lf concentrations in the milk of transgenic cows did not protect them from intramammary infection. All cows became infected and developed clinical mastitis. The rhLf-transgenic cows showed milder systemic signs and lower serum cortisol and haptoglobin concentrations than did controls. This may be explained by lipopolysaccharide-neutralizing and immunomodulatory effects of the high Lf concentrations in their milk. However, Lf does not seem to be a very efficient protein for genetic engineering to enhance the mastitis resistance of dairy cows.
Identification of a Novel Virulence Determinant with Serum Opacification Activity inStreptococcus suis
Authors: Baums Christoph G. , Kaim Ute , Fulde Marcus , Ramachandran Girish , Goethe Ralph , Valentin-Weigand Peter
Published: October 2006

Streptococcus suisserotype 2 is a porcine and human pathogen with adhesive and invasive properties. In other streptococci, large surface-associated proteins (>100 kDa) of the MSCRAMM family (microbial surface components recognizing adhesive matrix molecules) are key players in interactions with host tissue. In this study, we identified a novel opacity factor ofS. suis(OFS) with structural homology to members of the MSCRAMM family. The N-terminal region of OFS is homologous to the respective regions of fibronectin-binding protein A (FnBA) ofStreptococcus dysgalactiaeand the serum opacity factor (SOF) ofStreptococcus pyogenes. Similar to these two proteins, the N-terminal domain of OFS opacified horse serum. Serum opacification activity was detectable in sodium dodecyl sulfate extracts of wild-typeS. suisbut not in extracts of isogenicofsknockout mutants. Heterologous expression of OFS inLactococcus lactisdemonstrated that a high level of expression of OFS is sufficient to provide surface-associated serum opacification activity. Furthermore, serum opacification could be inhibited by an antiserum against recombinant OFS. The C-terminal repetitive sequence elements of OFS differed significantly from the respective repeat regions of FnBA and SOF as well as from the consensus sequence of the fibronectin-binding repeats of MSCRAMMs. Accordingly, fibronectin binding was not detectable in recombinant OFS. To investigate the putative function of OFS in the pathogenesis of invasiveS. suisdiseases, piglets were experimentally infected with an isogenic mutant strain in which theofsgene had been knocked out by an in-frame deletion. The mutant was severely attenuated in virulence but not in colonization, demonstrating that OFS represents a novel virulence determinant ofS. suis.
Comparison of the Inflammatory Responses of Human Meningeal Cells following Challenge withNeisseria lactamicaand withNeisseria meningitidis
Authors: Fowler Mark I. , Yin Kiave Y. Ho Wang , Humphries Holly E. , Heckels John E. , Christodoulides Myron
Published: October 2006

The rationale for the present study was to determine how different species of bacteria interact with cells of the human meninges in order to gain information that would have broad relevance to understanding aspects of the innate immune response in the brain.Neisseria lactamicais an occasional cause of meningitis in humans, and in this study we investigated the in vitro interactions betweenN. lactamicaand cells derived from the leptomeninges in comparison with the closely related organismNeisseria meningitidis, a major cause of meningitis worldwide.N. lactamicaadhered specifically to meningioma cells, but the levels of adherence were generally lower than those withN. meningitidis. Meningioma cells challenged withN. lactamicaandN. meningitidissecreted significant amounts of the proinflammatory cytokine interleukin-6 (IL-6), the C-X-C chemokine IL-8, and the C-C chemokines monocyte chemoattractant protein 1 (MCP-1) and RANTES, but it secreted very low levels of the cytokine growth factor granulocyte-macrophage colony-stimulating factor (GM-CSF). Thus, meningeal cells are involved in the innate host response toNeisseriaspecies that are capable of entering the cerebrospinal fluid. The levels of IL-8 and MCP-1 secretion induced by both bacteria were essentially similar. By contrast,N. lactamicainduced significantly lower levels of IL-6 thanN. meningitidis. Challenge with the highest concentration ofN. lactamica(108CFU) induced a small but significant down-regulation of RANTES secretion, which was not observed with lower concentrations of bacteria.N. meningitidis(106to 108CFU) also down-regulated RANTES secretion, but this effect was significantly greater than that observed withN. lactamica. Although both bacteria were unable to invade meningeal cells directly, host cells remained viable on prolonged challenge withN. lactamica, whereasN. meningitidisinduced death; the mechanism was overwhelming necrosis with no significant apoptosis. It is likely that differential expression of modulins betweenN. lactamicaandN. meningitidiscontributes to these observed differences in pathogenic potential.
Sensitized CD8+T Cells Fail To Control Organism Burden but Accelerate the Onset of Lung Injury duringPneumocystis cariniiPneumonia
Authors: Gigliotti Francis , Crow Elliott L. , Bhagwat Samir P. , Wright Terry W.
Published: October 2006

While CD8+cells have been shown to contribute to lung injury duringPneumocystis cariniipneumonia (PCP), there are conflicting reports concerning the ability of CD8+cells to killP. carinii.To address these two issues, we studied the effect of the presence of CD8+cells in two mouse models of PCP. In the reconstituted SCID mouse model, depletion of CD8+cells in addition to CD4+cells after reconstitution did not result in increased numbers ofP. cariniicysts compared to the numbers of cysts in mice with only CD4+cells depleted. This result was observed regardless of whether the mice were reconstituted with naïve orP. carinii-sensitized lymphocytes. In contrast, reconstitution with sensitized lymphocytes resulted in more rapid onset of lung injury that was dependent on the presence of CD8+cells. The course of organism replication over a 6-week period was also examined in the CD4+-T-cell-depleted and CD4+- and CD8+-T-cell-depleted mouse model of PCP. Again, the organism burdens were identical at all times regardless of whether CD8+cells were present. Thus, in the absence of CD4+T cells, CD8+T cells are a key contributor to the inflammatory lung injury associated with PCP. However, we were unable to demonstrate an in vivo effect of these cells on the course ofP. cariniiinfection.
Yersinia pseudotuberculosis
Adhesins Regulate Tissue-Specific Colonization and Immune Cell Localization in a Mouse Model of Systemic Infection
Authors: Hudson Krischan J. , Bouton Amy H.
Published: October 2006

Yersinia pseudotuberculosis
mutants deficient for the adhesins invasin and/or YadA were injected intravenously into BALB/c mice. Invasin expression inhibited colonization of the liver and spleen. YadA decreased liver colonization but promoted growth within the lung. The persistence of leukocytes within liver microabscesses correlated with enhanced colonization and lack of adhesin expression.
Toxin-Deficient Mutants of
Bacillus anthracis
Are Lethal in a Murine Model for Pulmonary Anthrax
Authors: Heninger Sara , Drysdale Melissa , Lovchik Julie , Hutt Julie , Lipscomb Mary F. , Koehler Theresa M. , Lyons C. Rick
Published: October 2006

Bacillus anthracis
, the etiologic agent of anthrax, produces at least three primary virulence factors: lethal toxin, edema toxin, and a capsule. The capsule is absolutely required for dissemination and lethality in a murine model of inhalation anthrax, yet the roles for the toxins during infection are ill-defined. We show in a murine model that when spores of specific toxin-null mutants are introduced into the lung, dissemination and lethality are comparable to those of the parent strain. Mutants lacking one or more of the structural genes for the toxin proteins, i.e., protective antigen, lethal factor, and edema factor, disseminated from the lung to the spleen at rates similar to that of the virulent parental strain. The 50% lethal dose (LD
50
) and mean time to death (MTD) of the mutants did not differ significantly from those of the parent. The LD
50
s or MTDs were also unaffected relative to those of the parent strain when mice were inoculated intravenously with vegetative cells. Nonetheless, histopathological examination of tissues revealed subtle but distinct differences in infections by the parent compared to some toxin mutants, suggesting that the host response is affected by toxin proteins synthesized during infection.
Evidence that Tight Junctions Are Disrupted Due to Intimate Bacterial Contact and Not Inflammation during Attaching and Effacing Pathogen Infection In Vivo
Authors: Guttman Julian A. , Samji Fereshte N. , Li Yuling , Vogl A. Wayne , Finlay B. Brett
Published: October 2006

It is widely accepted that tight junctions are altered during infections by attaching and effacing (A/E) pathogens. These disruptions have been demonstrated both in vitro and more recently in vivo. For in vivo experiments, the murine model of A/E infection withCitrobacter rodentiumis the animal model of choice. In addition to effects on tight junctions, these bacteria also colonize the colon at high levels, efface colonocyte microvilli, and cause hyperplasia and inflammation. Although we have recently demonstrated that tight junctions are disrupted byC. rodentium, the issue of direct effects of bacteria on epithelial cell junctions versus the indirect effects of inflammation still remains to be clarified. Here, we demonstrate that during theC. rodentiuminfections, inflammation plays no discernible role in the alteration of tight junctions. The distribution of the tight junction proteins, claudin-1, -3, and -5, are unaffected in inflamed colon, and junctions appear morphologically unaltered when viewed by electron microscopy. Additionally, tracer molecules are not capable of penetrating the inflamed colonic epithelium of infected mice that have cleared the bacteria. Finally, infected colonocytes from mice exposed toC. rodentiumfor 14 days, which have high levels of bacterial attachment to colonocytes as well as inflammation, have characteristic, altered claudin localization whereas cells adjacent to infected colonocytes retain their normal claudin distribution. We conclude that inflammation plays no discernible role in tight junction alteration during A/E pathogenesis and that tight junction disruption in vivo appears dependent only on the direct intimate attachment of the pathogenic bacteria to the cells.
Amino Acid Residues within EnterohemorrhagicEscherichia coliO157:H7 Tir Involved in Phosphorylation, α-Actinin Recruitment, and Nck-Independent Pedestal Formation
Authors: Allen-Vercoe Emma , Waddell Barbara , Toh Michael C. W. , DeVinney Rebekah
Published: October 2006

EnterohemorrhagicEscherichia coli(EHEC) O157:H7 and enteropathogenicE. coli(EPEC) adherence to epithelial cells results in the formation of actin pedestals. Pedestal formation requires the bacterial protein Tir, which is inserted into the epithelial cell plasma membrane by the type III secretion system. EPEC and EHEC use different Tir-based mechanisms for pedestal formation, and the EPEC Tir residues required have been well described. In contrast, little is known about the regions of EHEC O157:H7 Tir that are essential for pedestal formation. Additionally, EHEC O157:H7 Tir is serine/threonine phosphorylated, although the residues involved and their role in pedestal formation are not known. In this study, we describe two regions within the carboxy terminus of EHEC O157:H7 Tir that are required for phosphorylation and pedestal formation. Serines 436 and 437 are substrates for protein kinase A phosphorylation, although this is not required to form pedestals. Using a series of internal deletion mutants, we found that amino acids 454 to 463 are required for efficient pedestal formation. Deleting this region resulted in a significant decrease in the recruitment of both filamentous actin and the actin binding protein α-actinin. As α-actinin binds directly to the EHEC O157:H7 amino terminus, these data suggest that its recruitment is dependent on pedestal formation.
Spontaneous Recovery of Pathogenicity by
Leishmania major hsp100
−
/
−
Alters the Immune Response in Mice
Authors: Reiling Linda , Jacobs Thomas , Kroemer Manfred , Gaworski Iris , Graefe Sebastian , Clos Joachim
Published: October 2006

By using repeated mouse infection cycles, we obtained an escape variant with restored infectivity and pathogenicity that originated from a single, noninfectious
hsp100
−
/
−
gene (formerly known as Δ
clpB
) replacement clone of
Leishmania major
, the causative agent of cutaneous leishmaniasis. This isolate elicited increased infiltration of immune cells to the site of infection and altered the polarization of the immune response in BALB/c mice from a predominantly TH2 type to a TH1 type. A clonal analysis resulted in isolation of two clones with antagonistic properties. While one clone exhibited restored infectivity in isolated macrophages but caused no persistent infection in the mouse model, the second clone was unable to infect macrophages in vitro but could establish a lasting infection and form progressive lesions in BALB/c mice. Our results add to the evidence that the TH1-TH2 dichotomy of the early immune response against
L. major
not only depends on the genetic predisposition of the host but also depends on intrinsic properties of the parasite.
Early Gamma Interferon and Interleukin-2 Responses to Vaccination Predict the Late Resting Memory in Malaria-Naïve and Malaria-Exposed Individuals
Authors: Bejon Philip , Keating Sheila , Mwacharo Jedidah , Kai Oscar K. , Dunachie Susanna , Walther Michael , Berthoud Tamara , Lang Trudie , Epstein Judy , Carucci Daniel , Moris Philippe , Cohen Joe , Gilbert Sarah C. , Peshu Norbert , Marsh Kevin , Hill Adrian V. S.
Published: October 2006

Two different cell populations respond to potent T-cell-inducing vaccinations. The induction and loss of effector cells can be seen using an ex vivo enzyme-linked immunospot (ELISPOT) assay, but the more durable resting memory response is demonstrable by a cultured ELISPOT assay. The relationship of the early effector response to durable resting memory is incompletely understood. Effector phenotype is usually identified by gamma interferon (IFN-γ) production, but interleukin-2 (IL-2) has been specifically linked to the differentiation of memory cells. Here, IFN-γ- and IL-2-secreting effector cells were identified by an ex vivo ELISPOT assay 1 week after vaccination and compared with the resting memory responses detected by a cultured ELISPOT assay 3 months later. The different kinetics and induction of IL-2 by different vaccines and natural exposure are described. Furthermore, both early IFN-γ and IL-2 production independently predicted subsequent memory responses at 3 months in malaria-naïve volunteers, but only IFN-γ predicted memory in malaria-exposed volunteers. However, dual ELISPOT assays were also performed on malaria-exposed volunteers to identify cells producing both cytokines simultaneously. This demonstrated that double-cytokine-producing cells were highly predictive of memory. This assay may be useful in predicting vaccinations most likely to generate stable, long-term memory responses.
Localization of the Hypothetical Protein Cpn0797 in the Cytoplasm of
Chlamydia pneumoniae
-Infected Host Cells
Authors: Dong Feng , Flores Rhonda , Chen Ding , Luo Jianhua , Zhong Youmin , Wu Zhongming , Zhong Guangming
Published: October 2006

Using antibodies raised with chlamydial fusion proteins, we have localized a protein encoded by the hypothetical open reading frame Cpn0797 in the cytoplasm of
Chlamydia pneumoniae
-infected host cells. The anti-Cpn0797 antibodies specifically recognized Cpn0797 protein without cross-reacting with either CPAFcp or Cpn0796, the only two proteins known to be secreted into the host cell cytosol by
C. pneumoniae
organisms. Thus, Cpn0797 represents the third
C. pneumoniae
protein secreted into the host cell cytosol experimentally identified so far.
Tumor Necrosis Factor Alpha- and Inducible Nitric Oxide Synthase-Producing Dendritic Cells Are Rapidly Recruited to the Bladder in Urinary Tract Infection but Are Dispensable for Bacterial Clearance
Authors: Engel Daniel , Dobrindt Ulrich , Tittel André , Peters Petra , Maurer Juliane , Gütgemann Ines , Kaissling Brigitte , Kuziel William , Jung Steffen , Kurts Christian
Published: October 2006

The role of dendritic cells (DC) in urinary tract infections (UTI) is unknown. These cells contribute directly to the innate defense against various viral and bacterial infections. Here, we studied their role in UTI using an experimental model induced by transurethral instillation of the uropathogenic
Escherichia coli
(UPEC) strain 536 into C57BL/6 mice. While few DC were found in the uninfected bladder, many had been recruited after 24 h, mostly to the submucosa and uroepithelium. They expressed markers of activation and maturation and exhibited the CD11b
+
F4/80
+
CD8
−
Gr-1
−
myeloid subtype. Also, tumor necrosis factor alpha (TNF-α)- and inducible nitric oxide synthase (iNOS)-producing CD11b
INT
DC (Tip-DC) were detected, which recently were proposed to be critical in the defense against bacterial infections. However, Tip-DC-deficient CCR2
−/−
mice did not show reduced clearance of UPEC from the infected bladder. Moreover, clearance was also unimpaired in CD11c-DTR mice depleted of all DC by injection of diphtheria toxin. This may be explained by the abundance of granulocytes and of iNOS- and TNF-α-producing non-DC that were able to replace Tip-DC functionality. These findings demonstrate that some of the abundant DC recruited in UTI contributed innate immune effector functions, which were, however, dispensable in the microenvironment of the bladder.