bluuebunny/crossref_metadata_2025 huggingface dataset:
Rotary oscillation control of a cylinder wake
Authors: Tokumaru P. T. , Dimotakis P. E.
Published: April 2006

Exploratory experiments have been performed on circular cylinders executing forced rotary oscillations in a steady uniform flow. Flow visualization and wake profile measurements at moderate Reynolds numbers have shown that a considerable amount of control can be exerted over the structure of the wake by such means. In particular, a large increase, or decrease, in the resulting displacement thickness, estimated cylinder drag, and associated mixing with the free stream can be achieved, depending on the frequency and amplitude of oscillation.
The separated flow past a cylinder in a rotating frame
Authors: Becker Anne
Published: April 2006

In this paper a numerical model for the viscous flow past a cylinder in a rotating frame is discussed when both the Rossby number Ro and Ekman number E are small. The results of this model are analysed and compared to an inviscid study by Page (1987) applicable in the limit E → 0 with Ro = O(E½). The detailed structure of the separated flow is also examined and compared to the proposals for the higher-order flow in E¼ layers in Page (1987) which were based, in part, on the theory of Smith (1979, 1985) for the non-rotating flow past bluff bodies. Some discrepancies between this theory and the numerical results are noted.
Oscillations of magnetically levitated aspherical droplets
Authors: Cummings D. L. , Blackburn D. A.
Published: April 2006

In experiments to measure the surface energy of a magnetically levitated molten metal droplet by observation of its oscillation frequencies, Rayleigh's equation is usually used. This assumes that the equilibrium shape is a sphere, and the surface restoring force is due only to surface tension. This work investigates how the vibrations of a non-rotating liquid droplet are affected by the asphericity and additional restoring forces that the levitating field introduces. The calculations show that the expected single frequency of the fundamental mode is split into either three, when there is an axis of rotational symmetry, or five unequally spaced bands. Frequencies, on average, are higher than those of an unconstrained droplet; the surface tension appears to be increased over its normal value. This requires a small correction to be made in all analyses of surface energy. A frequency sum rule is derived from a simplified model of the magnetic field which allows the corresponding Rayleigh frequency to be evaluated from the observed frequencies of the fundamental and translational modes. A more detailed analysis shows a similar correction but one that is also sensitive to the position of the droplet in the field.
Distortion of line and surface elements in model turbulent flows
Authors: Drummond I. T. , Münch W.
Published: April 2006

Material lines and surfaces transported in a random velocity field undergo bending and stretching. In this paper we investigate the time evolution of curvature in line and surface elements both analytically and by numerical simulation for a simple model turbulence. Our analysis is close to that of Pope (1988) for the evolution of curvature in surface elements. We show that the equation governing the evolution of curvature in a line element is very similar to that governing the evolution of the principal curvature in a surface patch. We investigate the circumstances in which the effect of straining fluctuations is to cause the exponential rate of growth of curvature discovered by Pope et al. (1989). Our simulation confirms that the presence of helicity in the turbulent flow results in the development of a non-vanishing mean torsion in a line element. The results of the simulation also suggest that the generation of curvature tends to occur in regions different from those associated with rapid stretching. The generation of torsion, however, is found not to be correlated with either bending or stretching.
The continuous spectrum of the Orr-Sommerfeld equation: note on a paper of Grosch & Salwen
Authors: Craik A. D. D.
Published: April 2006

Grosch & Salwen (1978) discuss the continuous-spectrum contribution in both temporal and spatial stability problems that are governed by the linear Orr–Sommerfeld equation. Their computed temporal continuum eigenfunctions for the Blasius boundary layer and for a laminar jet profile show surprising differences. This note provides an improved physical understanding of the results through a simple model, and shows that these differences are more apparent than real.
The role of particle collisions in pneumatic transport
Authors: Louge M. Y. , Mastorakos E. , Jenkins J. T.
Published: April 2006

We analyse the dilute, steady, fully developed flow of relatively massive particles in a turbulent gas in the context of a vertical pipe. The idea is that the exchange of momentum in collisions between the grains and between the grains and the wall plays a significant role in the balance of forces in the particle phase. Consequently, the particle phase is considered to be a dilute system of colliding grains, in which the velocity fluctuations are produced by collisions rather than by the gas turbulence. The balance equations for rapid granular flow are modified to incorporate the drag force from the gas, and boundary conditions, based on collisional exchanges of momentum and energy at the wall, are employed. The turbulence of the gas is treated using a one-equation closure. A numerical solution of the resulting governing equations provides velocity and turbulent energy profiles in agreement with the measurements of Tsuji et al. (1984).
Longitudinal vorticity elements in boundary layers: nonlinear development from initial Görtler vortices as a prototype problem
Authors: Sabry A. S. , Liu J. T. C.
Published: April 2006

The nonlinear effects of longitudinal vorticity elements in boundary layers are studied via a prototype problem: the development of such vorticity elements from initial Görtler vortices in the amplified regime. While a time-dependent, quasi-two-dimensional formulation greatly simplifies the computational framework, full three-dimensionality of the velocity components is obtained. This temporal analogy for spatially developing flows approximates the nonlinear streamwise advection by a constant convection velocity, but the strong cross-sectional, advective nonlinearities are retained. Such an approximation lacks the stretching effect of the streamwise vorticity, since such elements are lifted into regions of higher streamwise velocities. That the temporal analogy is a good theoretical (and experimental) approximation to real developing flows is shown bya posterioriindications that the streamwise vorticity remains weak throughout the nonlinear region (though it has far-reaching nonlinear effects in upwelling in the peak region) and that the region of strong nonlinearities remains in the cross-sectional plane.

The aim of this work is to elucidate the nonlinearities producing sites of secondary instabilities and turbulence generation. The present mushroom-like computed iso-streamwise velocity contours surrounding the peak, as well as the streamwise velocity profiles in the peak and valley regions, agree well with experimental measurements up to the region of expected wavy secondary instabilities. Three local intense vorticity and enstrophy areas are found to be significant and these are thoroughly diagnosed. One such intense vorticity region arises from the upwelling of existing spanwise vorticity and subsequent spanwise stretching in the outer layers, leading to intense local high-shear layers of spanwise vorticity in the vicinity of the peak region, as expected. Primarily through the stretching of the vertical vorticity, intense vertical vorticity (and associated enstrophy) develop (i) in the shoulder regions of the mushroom-like iso-streamwise velocity structures in the outer layers of the boundary layer and (ii) in the inner regions of about thirty viscous lengths from the wall, close to the base of the mushroom-like structures. Of the three regions of intense local ‘free’ shear-layer vorticity, the vertical vorticity in the inner regions near the mushroom stem is dominant. This is entirely consistent with experimental observations of sites of high-frequency secondary and fine-scaled wavy instabilities. This theoretically/computationally obtained ‘parent flow’ essentially sets the stage for continued studies of its wavy instabilities. In order to analyse and control the shear stress at the wall and nonlinear flow development, the effect of initial parameters such as Görtler number, initial amplitudes and wavenumbers is fully explored.
Dissociation in Acute Stress Disorder After a Hyperventilation Provocation Test
Authors: Nixon Reginald D. V. , Bryant Richard A.
Published: April 2006

This study investigated the relationship of hyperarousal and dissociation in acute stress disorder (ASD). Civilian trauma survivors with ASD (n = 17) and without ASD (n = 15) and non-traumatized controls (n = 14) completed a hyperventilation provocation test and were administered the Beck Anxiety Inventory, the Anxiety Sensitivity Index, the Dissociative Experiences Scale, the Peritraumatic Dissociative Experiences Questionnaire, the Physical Reactions Scale, and the Agoraphobic Cognitions Questionnaire. Individuals with ASD demonstrated more panic, dissociation, and maladaptive interpretations about their arousal during the hyperventilation than non-ASD or control participants. Dissociation was associated with anxiety sensitivity and peritraumatic panic attacks. These findings suggest that hyperarousal and dissociation are highly associated in ASD and that catastrophic attributions may play a mediating role in this relationship.
Inkonsistenz und psychische Gesundheit: Eine Metaanalyse
Authors: Fries Alexander , Grawe Klaus
Published: April 2006

Zusammenfassung: Konsistenz im psychischen Geschehen gilt als Voraussetzung für gutes Funktionieren und für gute Gesundheit. Inkonsistenz dagegen verhindert eine effiziente Auseinandersetzung mit den Anforderungen der Umwelt und somit die Befriedigung der menschlichen Grundbedürfnisse, wird als Stressor gesehen und gilt als mitverantwortlich für die Entstehung von psychischen Störungen ( Grawe, 1998 , 2004 ). Inkongruenz als eine Art von Inkonsistenz beschreibt die Divergenz zwischen den Wahrnehmungen der Realität und den Wünschen und Zielen des Menschen. Diskordanz dagegen bezeichnet die gegenseitige Unvereinbarkeit von Zielen, Wünschen oder Motiven. Nach der Konsistenztheorie von Grawe spielen diese beiden Formen von Inkonsistenz, zusammen mit den Vermeidungszielen und dem Grad der Befriedigung von Grundbedürfnissen eine wichtige Rolle bei der Entstehung und Aufrechterhaltung von psychischen Störungen wie auch für das Wohlbefinden des Menschen. Die vorliegende Untersuchung gibt einen kurzen Überblick über Operationalisierungen von Inkonsistenzformen in der psychologischen Literatur und eine metaanalytische Zusammenfassung der Zusammenhänge zwischen Inkonsistenzformen und Merkmalen von Gesundheit und Krankheit. Die Ergebnisse entsprechen größtenteils den Annahmen der Konsistenztheorie. Inkonsistenzformen in unterschiedlichsten Operationalisierungen stehen im Zusammenhang mit Merkmalen von Wohlbefinden, Gesundheit und Krankheit. Zu berücksichtigen ist, dass die Ergebnisse meist aus Korrelationsstudien mit einem Messzeitpunkt stammen und deshalb nicht auf Ursache-Wirkungszusammenhänge geschlossen werden kann.
Insulin Reduces the BOLD Response but is without Effect on the VEP during Presentation of a Visual Task in Humans
Authors: Seaquist Elizabeth R , Chen Wei , Benedict Luke E , Ugurbil Kamil , Kwag Jae-Hwan , Zhu Xiao-Hong , Nelson Charles A
Published: April 2006

Functional magnetic resonance imaging (fMRI) based on blood oxygen level-dependent (BOLD) contrast has become an invaluable tool in the assessment of in vivo neuronal activation. Quantification of the BOLD response is determined by the hemodynamic and metabolic changes that occur in response to brain stimulation. However, these changes may vary by changes in insulin, a hormone known to be vasoactive in some tissues. To determine if insulin has an effect on fMRI, we measured the BOLD response to a visual stimulus in five normal volunteers in which insulin was first suppressed and then brought to a high physiological concentration. In addition, we also examined the effect of insulin on activation of the visual cortex as measured by the visual-evoked potential (VEP). We found that the BOLD response measured in the presence of insulin (serum insulin = 236±29pmol/L) was significantly lower ( P < 0.001) than that measured in its absence (serum insulin = 8±2pmol/L). Insulin was without effect on P100 amplitude or latency acquired in the presence or absence of insulin in 28 subjects using the same stimulus as that used for the fMRI experiments. Our observations suggest that insulin may have effects on cerebral blood flow and/or metabolism that affect the BOLD signal that are independent of its effects on neuronal activation identified by event related potentials (ERP). These findings highlight the complexity that must be considered when interpreting differences in fMRI responses between groups of subjects that differ in insulin concentration and/or insulin sensitivity.
Tuning the focus of a plasmonic lens by the incident angle
Authors: Liu Zhaowei , Steele Jennifer M. , Lee Hyesog , Zhang Xiang
Published: April 2006

We report the experimental realization of tuning the focus position of a plasmonic lens by adjusting the angle of the incident light similar to conventional lenses. A circular slit in silver film acts as both a surface plasmon polariton coupler and a plasmonic focusing lens. At small incident angles, the plasmonic lens has a very good focus with the position depending only on the angle of the incident beam. Numerical simulations of the focusing properties, including polarization dependence, agree well with experimental observations. This tunable plasmonic lens can be used in nanoscale photonics, biological sensing, and manipulation.
Friedel theorem for two dimensional relativistic spin-12 systems
Authors: Lin De-Hone
Published: April 2006

The Friedel sum rule is generalized to relativistic systems of spin-12 particles in two dimensions. The change in energy due to the presence of an impurity is studied. The relation of the sum rule with the relativistic Levinson theorem is presented. Density oscillations in such systems are discussed. Since the Friedel theorem has been of major importance in understanding the impurity scattering in materials, the present results may be useful to explain some phenomena in two dimensional fermionic many body systems.
Measurements of spatially growing dust acoustic waves in a dc glow discharge plasma
Authors: Thomas Edward
Published: April 2006

In this paper, an experiment is performed on dust acoustic waves in a dc glow discharge plasma. Stereoscopic particle image velocimetry (stereo-PIV) techniques are used to make measurements of the dust acoustic waves. These stereo-PIV measurements reveal the spatial growth of the waves over three to six wavelengths before reaching a saturated level. Experimental measurements are shown to agree with a simple model for spatially varying waves.
Laser-excited shear waves in solid and liquid two-dimensional dusty plasmas
Authors: Piel A. , Nosenko V. , Goree J.
Published: April 2006

The propagation of transverse waves in a two-dimensional particle suspension in a plasma is studied in the solid and liquid phase. The different states of the suspension are realized by raising the kinetic temperature of the dust particles with a new laser method. An additional laser beam is used to excite shear waves and the wave is observed by videomicroscopy in terms of the individual velocities of the dust particles. For recovering the spatial wave patterns the method of singular value decomposition is applied and compared with the method of spatial Fourier analysis of complex wave numbers. In the solid phase, weakly damped waves are found which follow the expected dispersion relation. In the liquid phase the existence of strongly damped waves is demonstrated. The real part of the wave number is in overall agreement with the predictions of the Quasi Localized Charge Approximation model for a two-dimensional system. The damping of the waves is discussed.
Two-fluid stationary states with dissipation and external drive
Authors: Bhattacharyya R. , Janaki M. S.
Published: April 2006

A formalism is developed for flowing two-fluid stationary states for an externally driven system with dissipation. For the standard reduced model (neglecting electron inertia effects) and assuming quasineutrality to hold, a flow-field coupling equation is proposed as the governing equation for the steady-state plasma. In the presence of only azimuthal flow a modified Grad-Shafranov (GS) equation is obtained. The GS is solved for the topology relevant to field-reversed configuration (FRC). The external electric field required to attain the configuration is obtained self-consistently.
Systematics of the new Australian wolf spider genus Tuberculosa (Araneae:Lycosidae)
Authors: Framenau Volker W. , Yoo Jung-Sun
Published: April 2006

The new Australian wolf spider genus Tuberculosa is revised, with T. harveyi, sp. nov. from the Northern Territory as type species. The genus includes a further three species from northern Queensland: T. austini, sp. nov., T. hoggi (Framenau & Vink, 2001), comb. nov. and T. monteithi, sp. nov. The genus is defined by a unique sexual dimorphism: males carry modified tubercular setae on the ventral side of the third coxae, which are here compared to the knobbed setae that can be found on the ventral surface of the abdomen in Hygrolycosa rubrofasciata Ohlert, 1865 and Passiena torbjoerni Lehtinen, 2005 from two different lycosid subfamilies. Based on the structure of the male pedipalp, Tuberculosa belongs to the subfamily Lycosinae sensu Dondale (1986) with close affinities to Venatrix Roewer, 1960, because males of both genera have a tubercle on the outer edges of their fangs and the cymbium tip carries claw-like macrosetae. A cladistic analysis of all four Tuberculosa species, based on 12 morphological characters and with Venatrix konei (Berland, 1924) as outgroup, revealed a topology with T. austini and T. harveyi as sister-species in the most derived clade (V. konei (T. monteithi (T. hoggi (T. harveyi, T. austini))). The distribution of Tuberculosa in the tropical north of Australia supports an origin of the genus, as well as its putative sister-genus Venatrix, in the Palaearctic region, in contrast to all other Australian Lycosinae, which appear to be of Gondwanan origin.
Australian treehoppers (Hemiptera:Membracidae:Centrotinae:Terentiini): phylogeny and biogeography
Authors: Wallace Matthew S. , Deitz Lewis L.
Published: April 2006

This work presents the first hypothesis of phylogenetic relationships among all 40 genera of the treehopper tribe Terentiini (Hemiptera : Membracidae : Centrotinae). This phylogeny, based on a parsimony analysis of 77 morphological characters, made possible an analytical approach to determining the likely ancestral host-plant family and geographic distribution of the tribe, based on present-day hosts and distributions. Of Australia’s 37 treehopper genera, 36 belong to the tribe Terentiini, with their centre of diversity in Queensland (30 genera). Optimisations of present-day distributions mapped on our phylogeny suggest that the ancestor of the tribe occurred in the Australian region, around north-eastern Australia (Queensland) and New Guinea (which has 8–10 terentiine genera). Subsequent dispersals from the Australian region (with 37 genera) took the tribe to the Indomalayan (11 genera) and Palaearctic (1 genus) regions. At least 13 terentiine genera include representatives that occur beyond the borders of Australia and New Guinea. Notable among the migrant lineages is the clade ‘Polonius + (Bulbauchenia + (Funkhouserella + Pyrgonota))’, which includes genera with such extraordinary pronotal modifications that some members were previously placed in separate tribes (Bulbaucheniini or Funkhouserellini). Members of this remarkable breakaway clade are known from Australia (Polonius only), Indonesia, the Malay Peninsula, Thailand, the Philippines, southern China (Taiwan and Hainan Island) and Japan. With regard to terentiine host plants, optimisations of present-day host associations point to the Leguminosae as the ancestral host family, even though plant families of Gondwanan origin, especially Myrtaceae and Proteaceae, are also prominent terentiine hosts. The overall evidence to date indicates that Terentiini are not a remnant of the early Gondwanan fauna, but rather a more recent tribe derived from Indomalayan ancestors.
Phosphorylation of TNF-α converting enzyme by gastrin-releasing peptide induces amphiregulin release and EGF receptor activation
Authors: Zhang Qing , Thomas Sufi M. , Lui Vivian Wai Yan , Xi Sichuan , Siegfried Jill M. , Fan Huizhou , Smithgall Thomas E. , Mills Gordon B. , Grandis Jennifer Rubin
Published: April 2006

G protein-coupled receptors induce EGF receptor (EGFR) signaling, leading to the proliferation and invasion of cancer cells. Elucidation of the mechanism of EGFR activation by G protein-coupled receptors may identify new signaling paradigms. A gastrin-releasing peptide (GRP)/GRP receptor-mediated autocrine pathway was previously described in squamous cell carcinoma of head and neck. In the present study, we demonstrate that TNF-α converting enzyme (TACE), a disintegrin and metalloproteinse-17, undergoes a Src-dependent phosphorylation that regulates release of the EGFR ligand amphiregulin upon GRP treatment. Further investigation reveals the phosphatidylinositol 3-kinase (PI3-K) as the intermediate of c-Src and TACE, contributing to their association and TACE phosphorylation. phosphoinositide-dependent kinase 1 (PDK1), a downstream target of PI3-K, has been identified as the previously undescribed kinase to directly phosphorylate TACE upon GRP treatment. These findings suggest a signaling cascade of GRP-Src-PI3-K-PDK1-TACE-amphiregulin-EGFR with multiple points of interaction, translocation, and phosphorylation. Furthermore, knockdown of PDK1 augmented the antitumor effects of the EGFR inhibitor erlotinib, indicating PDK1 as a therapeutic target to improve the clinical response to EGFR inhibitors.
All possible modes of gene action are observed in a global comparison of gene expression in a maize F
1
hybrid and its inbred parents
Authors: Swanson-Wagner Ruth A. , Jia Yi , DeCook Rhonda , Borsuk Lisa A. , Nettleton Dan , Schnable Patrick S.
Published: April 2006

Heterosis is the phenomenon whereby the progeny of particular inbred lines have enhanced agronomic performance relative to both parents. Although several hypotheses have been proposed to explain this fundamental biological phenomenon, the responsible molecular mechanisms have not been determined. The maize inbred lines B73 and Mo17 produce a heterotic F
1
hybrid. Global patterns of gene expression were compared in seedlings of these three genotypes by using a microarray that contains 13,999 cDNAs. Using an estimated 15% false discovery rate as a cutoff, 1,367 ESTs (9.8%) were identified as being significantly differentially expressed among genotypes. All possible modes of gene action were observed, including additivity, high- and low-parent dominance, underdominance, and overdominance. The largest proportion of the ESTs (78%; 1,062 of 1,367) exhibited expression patterns that are not statistically distinguishable from additivity. Even so, 22% of the differentially regulated ESTs exhibited nonadditive modes of gene expression. Classified on the basis of significant pairwise comparisons of genotype means, 181 of these 305 nonadditive ESTs exhibited high-parent dominance and 23 exhibited low-parent dominance. In addition, 44 ESTs exhibited underdominance or overdominance. These findings are consistent with the hypothesis that multiple molecular mechanisms, including overdominance, contribute to heterosis.
Observations on related ecological exponents
Authors: Southwood T. Richard E. , May Robert M. , Sugihara George
Published: April 2006

We observe a relationship among three independently derived power laws in ecology: (
i
) total number of species versus area, (
ii
) species frequency versus species length, and (
iii
) maximal body size versus area. Aside from showing how these historically disparate phenomena are connected, we show how recent empirical results relating the maximal body size of top terrestrial vertebrates to the square root of land area conform to a prior theoretical expectation given by two of the above power laws. Of particular interest is the observation that the exponent relating species length to species frequency suggests a dimension for niche space for terrestrial vertebrate assemblages of
D
≈ 3/2. This value, along with power law for maximal body size, versus area, gives rise to the canonical species area exponent
z
≈ 1/4.
Persistence of nevirapine-resistant HIV-1 in women after single-dose nevirapine therapy for prevention of maternal-to-fetal HIV-1 transmission
Authors: Palmer S. , Boltz V. , Martinson N. , Maldarelli F. , Gray G. , McIntyre J. , Mellors J. , Morris L. , Coffin J.
Published: April 2006

Single-dose nevirapine (sdNVP) for prevention of mother-to-child transmission of HIV-1 can select nevirapine (NVP)-resistant variants, but the frequency, duration, and clinical significance of this resistance is not well defined. We used a sensitive allele-specific PCR assay to assess the emergence and persistence of NVP-resistant variants in plasma samples from 22 women with HIV-1 subtype C infection who participated in a study of sdNVP for prevention of mother-to-child transmission of HIV-1. The women were categorized into three groups on the basis of detection of NVP resistance by standard genotype analysis. Group 1 (
n
= 6) had NVP resistance detected at 2 and 6 mo after sdNVP, but not at 12 mo. Group 2 (
n
= 9) had NVP resistance detected at 2 mo, but not 6 mo. Group 3 (
n
= 7) had no NVP resistance detected at any time point. Allele-specific PCR analysis for the two most common NVP resistance mutations (K103N and Y181C) detected NVP-resistant variants in most (16 of 21) samples that were negative for NVP resistance by standard genotype, at levels ranging from 0.1% to 20% 1 yr after treatment. The frequency of NVP-resistant mutations decreased over time, but persisted above predose levels for more than 1 yr in ≥23% of the women. These findings highlight the urgent need for studies assessing the impact of sdNVP on the efficacy of subsequent antiretroviral therapy containing NVP or other nonnucleoside reverse transcriptase inhibitors.
Pre-B cell proliferation and lymphoblastic leukemia/high-grade lymphoma in Eμ-miR155 transgenic mice
Authors: Costinean Stefan , Zanesi Nicola , Pekarsky Yuri , Tili Esmerina , Volinia Stefano , Heerema Nyla , Croce Carlo M.
Published: April 2006

MicroRNAs (miRNAs) represent a newly discovered class of posttranscriptional regulatory noncoding small RNAs that bind to targeted mRNAs and either block their translation or initiate their degradation. miRNA profiling of hematopoietic lineages in humans and mice showed that some miRNAs are differentially expressed during hematopoietic development, suggesting a role in hematopoietic cell differentiation. In addition, recent studies suggest the involvement of miRNAs in the initiation and progression of cancer. miR155 and BIC, its host gene, have been reported to accumulate in human B cell lymphomas, especially in diffuse large B cell lymphomas, Hodgkin lymphomas, and certain types of Burkitt lymphomas. Here, we show that Eμ-mmu-miR155 transgenic mice exhibit initially a preleukemic pre-B cell proliferation evident in spleen and bone marrow, followed by frank B cell malignancy. These findings indicate that the role of miR155 is to induce polyclonal expansion, favoring the capture of secondary genetic changes for full transformation.
Influence of the Descending Thoracic Aortic Cross Clamping on Bispectral Index Value and Plasma Propofol Concentration in Humans
Authors: Kakinohana Manabu , Nakamura Seiya , Fuchigami Tatsuya , Miyata Yuji , Sugahara Kazuhiro
Published: April 2006

Background

In this study, the authors investigated changes in Bispectral Index (BIS) values and plasma propofol concentrations (Cp) after aortic cross clamping in the descending thoracic aortic aneurysm repair surgery during propofol anesthesia.

Methods

Prospectively, in 10 patients undergoing thoracic aortic surgery during total intravenous anesthesia with propofol, BIS values were recorded during cross clamping of the descending thoracic aorta. In this study, the rate of propofol infusion was controlled to keep the BIS value between 30 and 60 throughout surgery. Simultaneously, Cp values in the blood samples taken from the right radial artery (area proximal to cross clamping) and the left femoral artery (area distal to cross clamping) were measured.

Results

Approximately 15 min after initiating aortic cross clamping, BIS values in all cases started to decrease abruptly. Cp values of samples taken from the radial artery after cross clamping of the aorta were significantly (P < 0.05) increased compared with pre-cross clamp values (1.8 +/- 0.4 microg/ml), and the mean Cp after aortic cross clamping varied between 3.0 and 5.3 microg/ml. In addition, there were significant differences in the Cp values between radial arterial and femoral arterial blood samples throughout aortic cross clamping. Cp values in samples from the radial artery were approximately two to seven times higher than those from the femoral artery.

Conclusions

This study showed that Cp values increased and BIS values decreased rapidly after aortic cross clamping in thoracic aortic aneurysm repair surgery during propofol anesthesia. These findings suggested that all anesthesiologists should control the infusion rate carefully, taking the abrupt changes in its pharmacokinetics into consideration, especially during cross clamping of the descending thoracic aorta.
Ropivacaine Decreases Inflammation in Experimental Endotoxin-induced Lung Injury
Authors: Blumenthal Stephan , Borgeat Alain , Pasch Thomas , Reyes Livia , Booy Christa , Lambert Maud , Schimmer Ralph C. , Beck-Schimmer Beatrice
Published: April 2006

Background

Endotoxin causes acute lung injury, which can lead to acute respiratory distress syndrome. Because local anesthetics are known to attenuate inflammatory reactions, ropivacaine was tested for its possible antiinflammatory effect in lipopolysaccharide-induced lung injury in rat alveolar epithelial cells (AECs) and rat pulmonary artery endothelial cells (RPAECs) in vitro and in vivo.

Methods

AECs and RPAECs were stimulated for 4 h with lipopolysaccharide or lipopolysaccharide and 1 mum ropivacaine. Messenger RNA (mRNA) for intercellular adhesion molecule 1 was assessed. Isolated neutrophils were incubated with stimulated target cells to quantify adhesion and neutrophil-induced cytotoxicity in AECs and RPAECs. In vivo, lipopolysaccharide was instilled intratracheally with or without 1 mm intratracheally or intravenously administered ropivacaine. Bronchoalveolar lavage was performed 5 h later to determine neutrophil and albumin content, as well as concentrations of inflammatory mediators.

Results

In AECs and RPAECs, ropivacaine attenuated lipopolysaccharide-induced up-regulation of mRNA for intercellular adhesion molecule 1 by 41% and 24%, respectively (P < 0.05). In the presence of ropivacaine, increased neutrophil adhesion was down-regulated by 58% and 44% (P < 0.005), whereas cytotoxicity in AECs and RPAECs was diminished by 28% and 33%, respectively (P < 0.05). Enhanced neutrophil count in lipopolysaccharide lungs was reduced by 56% in the presence of intratracheally instilled ropivacaine (81% with intravenous ropivacaine; P < 0.005). Albumin was decreased by 46% with intratracheal ropivacaine (38% with intravenous ropivacaine; P < 0.05), and inflammatory mediators were decreased by 48-59% (69-81% with intravenous ropivacaine; P < 0.01).

Conclusions

Ropivacaine intervention substantially attenuated the inflammatory response in acute lung injury and thus may carry an interesting potential for antiinflammatory treatment.
Exocrine Pancreatic Function in Children with Progressive Familial Intrahepatic Cholestasis Type 2
Authors: Walkowiak Jaroslaw , Jankowska Irena , Pawlowska Joanna , Strautnieks Sandra , Bull Laura , Thompson Richard , Herzig Karl‐Heinz , Socha Jerzy
Published: April 2006

In progressive familial intrahepatic cholestasis type 2 (PFIC‐2), severe steatorrhea is often documented. However, pancreatic exocrine secretion has not yet been studied. In 14 children with PFIC‐2, pancreatic function was assessed using standard fecal tests. Normal fecal lipase concentrations excluded isolated lipase deficiency. No differences in fecal elastase‐1 concentrations and chymotrypsin activities were detected between PFIC‐2 patients with or without steatorrhea, nor between these patients and healthysubjects. In conclusion, pancreatic exocrine function in patients with PFIC‐2 is normal. Steatorrhea observed in those patients isnot related to pancreatic insufficiency.
Structure of the Sir3 protein bromo adjacent homology (BAH) domain from S. cerevisiae at 1.95 Å resolution
Authors: Hou Zhonggang , Danzer John R. , Fox Catherine A. , Keck James L.
Published: April 2006

Sir3p is a silent‐information‐regulator (SIR) protein required for the assembly of a transcriptionally “silent” chromatin structure at telomeres and the cryptic HM mating‐type loci in Saccharomyces cerevisiae. Sir3p contains a putative “bromo adjacent homology” (BAH) domain at its N terminus that shares strong sequence similarity with the BAH domain of a subunit of the origin recognition complex (ORC), Orc1p. The Orc1p–BAH domain forms a well‐defined complex with the ORC interaction region (OIR) of another Sir protein, Sir1p, which targets formation of silent chromatin to the HM‐loci. Interestingly, despite sequence similarity of the Sir3p and Orc1p BAH domains and Sir3p's established importance in silencing, Sir3p does not bind the Sir1p–OIR. Here we report the 1.95 Å resolution crystal structure of the Sir3p–BAH domain. The structure reveals two key features that can account for Sir3p–BAH domain's inability to interact with Sir1p. First, several Orc1p–BAH domain residues known to directly contact Sir1p are altered in the Sir3p–BAH domain. Second, a critical OIR‐binding pocket present on the surface of the Orc1p–BAH domain is “filled” in the Sir3p–BAH domain structure, potentially making it inaccessible to Sir1p. These findings imply that the Sir3p–BAH domain structure has evolved for functions distinct from those of the Orc1p–BAH domain.
Abnormalities of the Hippocampus are Similar in Deoxycorticosterone Acetate‐Salt Hypertensive Rats and Spontaneously Hypertensive Rats
Authors: Pietranera L. , Saravia F. , Gonzalez Deniselle M. C. , Roig P. , Lima A. , De Nicola A. F.
Published: April 2006

Hippocampal neuropathology is a recognised feature of the brain in spontaneously hypertensive rats (SHR), but similar studies are lacking in another model of hypertension, the mineralocorticoid‐salt‐treated rat. The present study aimed to compare changes in hippocampal parameters in 16‐week‐old male SHR (blood pressure approximately 190 mmHg) and their normotensive Wistar‐Kyoto controls, with those of male Sprague‐Dawley rats receiving (i) 10 mg deoxycorticosterone acetate (DOCA) every other day during 3 weeks and drinking 1% NaCl solution (blood pressure approximately 160 mmHg) and normotensive controls treated with (ii) DOCA and drinking water, (iii) drinking water only or (iv) 1% NaCl only. In these experimental groups, we determined: (i) cell proliferation in the dentate gyrus (DG) using the 5‐bromo‐2′‐deoxyuridine‐labelling technique; (ii) the number of glial fibrillary acidic protein (GFAP) positive astrocytes under the CA1, CA3 and DG; (iii) the number of apolipoprotein E (ApoE) positive astrocytes as a marker of potential neuronal damage; and (iv) the number of neurones in the hilus of the DG, taken as representative of neuronal density in other hippocampal subfields. Changes were remarkably similar in both models, indicating a decreased cell proliferation in DG, an increased number of astrocytes immunopositive for GFAP and ApoE and a reduced number of hilar neurones. Although hypertension may be a leading factor for these abnormalities, endocrine mechanisms may be involved, because hypothalamic‐pituitary function, mineralocorticoid receptors and sensitivity to mineralocorticoid treatment are stimulated in SHR, whereas high exogenous mineralocorticoid levels circulate in DOCA‐treated rats. Thus, in addition to the deleterious effects of hypertension, endocrine factors may contribute to the abnormalities of hippocampus in SHR and DOCA‐treated rats.
5,6‐Dimethylxanthenone‐4‐acetic acid treatment of a non‐immunogenic tumour does not synergize with active or passive CD8+ T‐cell immunotherapy
Authors: Matthews Kate E , Hermans Ian F , Roberts Joanna M , Ching Lai‐Ming , Ronchese Franca
Published: April 2006

The chemotherapeutic drug 5,6‐dimethylxanthenone‐4‐acetic acid (DMXAA) inhibits intratumoural blood flow, causing hypoxia, haemorrhagic necrosis, vascular collapse and tumour cell death. Production of TNF‐α and IFN is also induced, causing local inflammation and activation of immune cells including CD8+ T cells. We used the tumour cell line LL‐LCMV, which expresses the gp33 epitope of lymphocytic choriomeningitis virus in a non‐immunogenic form, to investigate whether tumour cell death caused by treatment with DMXAA may improve the success of tumour immunotherapy mediated by CD8+ T cells. Treatment with DMXAA was effective at reducing the size of LL‐LCMV tumours. However, compared to normal mice, tumour reduction was no more marked or sustained in mice carrying high numbers of naive, tumour‐specific CD8+ T cells. The antitumour effect of activated CD8+ T cells was also not affected by DMXAA treatment. Tumour‐specific CD8+ T cells activated in vivo by immunization with dendritic cells and specific tumour peptide antigen, or generated in vitro and adoptively transferred into tumour‐bearing mice by i.v. injection, did not improve or sustain the reduction in tumour size induced by DMXAA treatment. We conclude that the presence of high numbers of naive CD8+ T cells, or immunotherapies leading to CD8+ T‐cell activation, do not synergize with the tumour cell death and local inflammation induced by DMXAA treatment. It is possible that this lack of synergism may result from both treatments inducing activation of CD8+ T cells and that treatments that activate different populations of immune cells may achieve better success.
Genetic analysis of psychiatric disorders in humans
Authors: Van Belzen M. J. , Heutink P.
Published: April 2006

Psychiatric disorders place a large burden not only on affected individuals and their families but also on societies and health services. Current treatment is only effective in a proportion of the patients, so considerable effort has been put into the development of new medications. The susceptibility to all major psychiatric disorders is, at least in part, genetic. Knowledge of the genes that underlie this susceptibility may lead to the identification of new drug targets and the development of more effective treatments. Therefore, numerous genetic studies in search for the genes involved in psychiatric disorders have been performed. Although results of both linkage and association studies have been inconsistent, several promising gene regions and candidate genes have been identified recently. In this article, we will review the strategies that proved to be successful in detecting genes for psychiatric disorders and we will provide some recommendations to increase the probability of detecting susceptibility genes in genetic studies of different designs.
A hitchhiker's guide to behavioral analysis in laboratory rodents
Authors: Sousa N. , Almeida O. F. X. , Wotjak C. T.
Published: April 2006

Genes and environment are both essential and interdependent determinants of behavioral responses. Behavioral genetics focuses on the role of genes on behavior. In this article, we aim to provide a succinct, but comprehensive, overview of the different means through which behavioral analysis may be performed in rodents. We give general recommendations for planning and performing behavioral experiments in rats and mice, followed by brief descriptions of experimental paradigms most commonly used for the analysis of reflexes, sensory function, motor function and exploratory, social, emotional and cognitive behavior. We end with a discussion of some of the shortcomings of current concepts of genetic determinism and argue that the genetic basis of behavior should be analyzed in the context of environmental factors.
Antifungal Activity of C-27 Steroidal Saponins
Authors: Yang Chong-Ren , Zhang Ying , Jacob Melissa R. , Khan Shabana I. , Zhang Ying-Jun , Li Xing-Cong
Published: April 2006

As part of our search for new antifungal agents from natural resources, 22 C-27 steroidal saponins and 6 steroidal sapogenins isolated from several monocotyledonous plants were tested for their antifungal activity against the opportunistic pathogens
Candida albicans
,
Candida glabrata
,
Candida krusei
,
Cryptococcus neoformans
, and
Aspergillus fumigatus
. The results showed that the antifungal activity of the steroidal saponins was associated with their aglycone moieties and the number and structure of monosaccharide units in their sugar chains. Within the 10 active saponins, four tigogenin saponins (compounds 1 to 4) with a sugar moiety of four or five monosaccharide units exhibited significant activity against
C. neoformans
and
A. fumigatus
, comparable to the positive control amphotericin B. The antifungal potency of these compounds was not associated with cytotoxicity to mammalian cells. This suggests that the C-27 steroidal saponins may be considered potential antifungal leads for further preclinical study.
Predictors of Mortality in Patients with Bloodstream Infection Due to Ceftazidime-Resistant
Klebsiella pneumoniae
Authors: Anderson Deverick J. , Engemann John J. , Harrell Lizzie J. , Carmeli Yehuda , Reller L. Barth , Kaye Keith S.
Published: April 2006

Bloodstream infection (BSI) due to multidrug-resistant
Klebsiella
is associated with high rates of morbidity and mortality. The aim of this study was to identify predictors of in-hospital mortality among patients with BSI due to ceftazidime-resistant (CAZ-R)
Klebsiella pneumoniae
at a tertiary care medical center. Patients with CAZ-R
K. pneumoniae
BSI were identified by our microbiology laboratory between January 1995 and June 2003. Clinical data were collected retrospectively. Logistic regression was used to identify independent predictors of all causes of in-hospital mortality. Of 779 patients with
K. pneumoniae
BSI, 60 (7.7%) had BSI due to CAZ-R
K. pneumoniae
; 43 (72%) of these were nosocomial infections. Pulsed-field gel electrophoresis identified a single predominant strain in 17 (28%) patients. The in-hospital mortality rate was 43% (
n
= 26). Among patients with CAZ-R
K. pneumoniae
BSI, those who died were similar to survivors with respect to demographic, clinical, and antimicrobial susceptibility characteristics. Only 43 (72%) patients received effective therapy within 5 days of BSI. In bivariable analysis, delay in initiation of effective therapy for >72 h after diagnosis of BSI was associated with death (
P
= 0.03). Strain genotype was not predictive of outcome. In multivariable analysis, delay in initiation of effective therapy for >72 h after diagnosis of BSI was an independent predictor of death (odds ratio, 3.32; 95% confidence interval, 1.07 to 10.3). Thus, among patients with BSI due to CAZ-R
K. pneumoniae
, a delay in the initiation of effective therapy of greater than 72 h after BSI was associated with a >3-fold increase in mortality risk.
EDTA as an Adjunct Antifungal Agent for Invasive Pulmonary Aspergillosis in a Rodent Model
Authors: Hachem Ray , Bahna Paul , Hanna Hend , Stephens L. Clifton , Raad Issam
Published: April 2006

Rats immunosuppressed by the administration of cyclophosphamide and cortisone acetate and then infected with
Aspergillus fumigatus
were treated with an antifungal drug, EDTA, or a combination of one of the antifungal agents, amphotericin B lipid complex (ABLC; 5 mg/kg of body weight/day for 7 days), and EDTA (30 mg/kg/day for 7 days). The mortality rate was reduced, the duration of survival was increased, fewer
A. fumigatus
organisms were recovered from the lungs, and less-severe lung lesions were seen histopathologically in the rats receiving the combination treatment than in the rats receiving either an antifungal agent or EDTA alone. Further studies regarding the mechanisms of EDTA and its interactions with ABLC are warranted, and further studies are needed to more fully examine the safety, tolerance, and optimal dosing of EDTA in the treatment of this and other fungal infections.
Photoinactivation of Mycobacteria In Vitro and in a New Murine Model of LocalizedMycobacterium bovisBCG-Induced Granulomatous Infection
Authors: O'Riordan Katie , Sharlin David S. , Gross Jerome , Chang Sung , Errabelli Divya , Akilov Oleg E. , Kosaka Sachiko , Nau Gerard J. , Hasan Tayyaba
Published: April 2006

Treatment of tuberculosis is currently hindered by prolonged antibiotic regimens and the emergence of significant drug resistance. Alternatives and adjuncts to standard antimycobacterial agents are needed. We propose that a direct attack utilizing photosensitizers and light-based treatments may be effective in curtailingMycobacterium tuberculosisin discrete anatomical sites in the most infectious phase of pulmonary tuberculosis. To demonstrate experimental proof of principle, we have applied established photodynamic therapy (PDT) technology to in vitro cultures and an in vivo mouse model usingMycobacterium bovisBCG. We report here in vitro and in vivo PDT efficacy studies and the use of a three-dimensional collagen gel as a delivery vehicle for BCG, subcutaneously inserted, to induce specifically localized granuloma-like lesions in mice. When a benzoporphyrin derivative was utilized as the photosensitive agent, exposure to light killed extracellular and intracellular BCG in significant numbers. Collagen scaffolds containing BCG inserted in situ in BALB/c mice for 3 months mimicked granulomatous lesions and demonstrated a marked cellular infiltration upon histological examination, with evidence of caseating necrosis and fibrous capsule formation. When 105BCG were present in the in vivo-induced granulomas, a significant reduction in viable mycobacterial cells was demonstrated in PDT-treated granulomas compared to those of controls. We conclude that PDT has potential in the treatment of localized mycobacterial infections, such as pulmonary granulomas and cavities.