bluuebunny/crossref_metadata_2025_split huggingface dataset:
The stability of elliptical vortices in an external straining flow
Authors: Dritschel David G. 
Published: April 2006

Subject to uniform strain, an elliptical patch of vorticity in an in viscid, incompressible, two-dimensional fluid generally rotates or nutates and extends or compresses while retaining a precisely elliptical shape (the Kida solutions). This result is of interest because the uniform strain idealizes the leading-order distortional influence of distant vortices in a flow with many vortices. Because of the unsteady motion of the distant vortices, both the strain rate and the rotation rate of the strain axes typically vary with time. In the special case that the strain rate and rotation rate are steady, and when the strain rate is not too large, periodic motion of an elliptical vortex is possible. Larger strain rates lead to indefinite extension of the vortex.Uniform strain, however, only approximately mimics the effect of distant vortices. The local variations- in the strain field around a vortex disturb the vortex, preventing it from retaining a simple, elliptical shape. These disturbances may amplify because of instabilities. In this paper, we examine the stability of periodic elliptical motion to small boundary disturbances, for the case of steady, uniform strain and rotation rate, first by linear Floquet theory and then by direct, high-resolution, nonlinear numerical integrations. It is discovered that a significant portion of the periodic solutions are linearly unstable. Instability can occur even when the strain rate is arbitrarily small and the basic motion arbitrarily close to circular. Extended nonlinear calculations exhibit recurrence, in some cases, and attrition of the vortex by repeated wave amplification, steepening, and breaking in others.
Axisymmetric creeping motion of drops through circular tubes
Authors: Martinez M. J. , Udell K. S. 
Published: April 2006

The axisymmetric creeping motion of a neutrally buoyant deformable drop flowing through a circular tube is analysed with a boundary integral equation method. The fluids are immiscible, incompressible, and the bulk flow rate is constant. The drop to suspending fluid viscosity ratio is arbitrary and the drop radius varies from 0.5 to 1.15 tube radii. The effects of the capillary number, viscosity ratio, and drop size on the deformation, the drop speed, and the additional pressure loss are examined.Drops with radius ratios less than 0.7 are insensitive to substantial variation in capillary number and viscosity ratio, and computed values of drop speed and extra pressure loss are in excellent agreement with small deformation theories (Hestroni et al. 1970; Hyman & Skalak 1972a). For this drop size range, significant deformation will result only for Ca > 0.25. The onset of a re-entrant cavity is predicted at the trailing end of the drop for Ca ≈ 0.75. Drop speed and meniscus shape become independent of drop size for radius ratios as small as 1.10. The extra pressure loss can be positive or negative depending mainly on the viscosity ratio, however a relatively inviscid drop can cause a positive extra pressure loss when capillary forces are significant. Computed values for extra pressure loss and drop speed are in good agreement with the experimental data of Ho & Leal (1975) for drops of sizes comparable with the tube radius.
The nonlinear growth of surface-tension-driven instabilities of a thin annular film
Authors: Johnson Mark , Kamm Roger D. , Ho Lee Wing , Shapiro Ascher , Pedley T. J. 
Published: April 2006

The stability and initial growth rate of disturbances on an annular film lining a cylindrical tube have been the focus of several previous works. The further development of thsse disturbances as they grow to form stable unduloids or liquid bridges is investigated by means of a thin-film integral model. The model is compared both with perturbation theories for early times, and a numerical solution of the exact equations (NEKTON) for later times. The thin-film model gave results that were in good agreement with solutions of the exact equations. The results show that linear perturbation theory can be used to give good estimates of the times for unduloid and liquid bridge formation. The success of the model derives from the dominant influence of narrow draining regions that feed into the growing unduloid, and these regions remain essentially one-dimensional throughout the growth of the instability.The model is used to analyse the evolution of the liquid layer lining the small airways of the lung during a single breath. The timescales for formation of unduloids and liquid bridges are found to be short enough for the liquid layer to be in a virtually quasi-equilibrium state throughout the breathing cycle. This conclusion is only tentative, however, because the model assumes that the surface tension of the airway liquid lining does not change with changes in interfacial area despite the known presence of pulmonary surfactant.
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.
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

ABSTRACTIn 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

AbstractSir3p 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

AbstractHippocampal 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.
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

ABSTRACT

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

ABSTRACT

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

ABSTRACT

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

ABSTRACTTreatment 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.