bluuebunny/crossref_metadata_2025 huggingface dataset:
Acquired long QT syndrome and elective anesthesia in children
Authors: CURRY TIMOTHY B. , GAVER RENEE , WHITE ROGER D.
Published: February 2006

We present the case of a child who had had a previous episode of torsades de pointes (TdP) and who was scheduled for elective surgery under general anesthesia. The pathophysiology of this condition and the anesthesia concerns are discussed. An 8‐year‐old male with a history of osteogenic sarcoma had undergone an uneventful limb salvage procedure 2 years earlier. During a subsequent admission to the hospital, he had had a cardiopulmonary arrest with complete recovery. Telemetry electrocardiogram (ECG) rhythm recordings obtained during the event showed TdP that degenerated into ventricular fibrillation, which then terminated spontaneously. On a subsequent ECG, the QTc interval was 694 ms. The prolonged QT interval was attributed to homeopathic use of cesium chloride supplements and the QT interval normalized after cesium was stopped. He presented for an elective procedure and, with an anesthetic plan that emphasized medications without known effect on the QT interval, had an uneventful perioperative course. The optimal anesthesia plan for patients with prolonged QT or those suspected to be at risk for prolongation of the QT interval has not been well described. Available evidence suggests that using total intravenous anesthesia with propofol may be the safest and was used uneventfully in this case. Additionally, this case emphasizes the need to inquire about the use of supplements and naturopathic medications, even in children, that may have life‐threatening side effects or interactions with anesthetic agents.
Incorporating uncertainty in spatial structure for viability predictions: a case study of California sea lions (Zalophus californianus californianus)
Authors: Gonzalez‐Suarez M. , McCluney K. E. , Aurioles D. , Gerber L. R.
Published: February 2006

In recent years, population viability analysis has become a popular tool to assess the relative risk of extinction among populations. Viability estimates for spatially structured populations require movement data that are often unavailable. In this paper, a diffusion approximation model was used to explore the effects of different spatial scenarios resulting from assumptions about movement rates. Census data for 13 breeding islands occupied by California sea lions Zalophus californianus californianus in the Gulf of California were used to explore three potential scenarios: unlimited movement between sites (panmictic population), limited movement (several clusters of populations) and no movement between islands (isolated islands). Predicted viability estimates were different for each scenario, but contrary to expectations, the mean extinction risk estimates were generally lowest when movement was unlimited (panmictic scenario). However, despite an extensive dataset, the confidence of the viability predictions for each scenario was low. In some cases, uncertainty in predictions within a scenario was greater than differences between scenarios. Therefore, it is recommended that in situations where movement rates and spatial structure are unknown, extinction risk estimates should reflect both the confidence intervals for each risk estimate and the uncertainty resulting from different spatial scenarios. This study also provides the first estimate of population viability (considering spatial structure) for California sea lions in the Gulf of California and an evaluation of population status based on the IUCN criteria for species listing.
A model of preverbal social development and its application to social dysfunctions in autism
Authors: Berger Michael
Published: February 2006

Studies of early face perception are used to develop a model of how face expressions might be transduced to initiate consonant internal affect, related outward expressions and other behaviours. Underlying neural mechanisms and processes are identified. The model is generalised to offer an account of aspects of typical preverbal social development. It is then used to develop aetiological hypotheses about the lack of social interest and motivation in autism and to provide a framework for evaluating other theories of autism. Although derived from existing literature, the model offers a distinctive account.
Screening of ESTs from Septoria musiva (teleomorph Mycosphaerella populorum) for detection of SSR and PCR–RFLP markers
Authors: FEAU NICOLAS , JACOBI VOLKER , HAMELIN RICHARD C. , BERNIER LOUIS
Published: February 2006

The development of an expressed sequence tag (EST) collection for the poplar pathogen Septoria musiva presented an opportunity for the development of locus‐specific polymorphic markers. Five microsatellites simple sequence repeat (SSR) and six polymerase chain reaction (PCR)–restriction fragment length polymorphism (RFLP) markers were identified and tested on three S. musiva populations collected in the north‐central and northeastern regions of North America. The results obtained support previously published random amplified polymorphic DNA (RAPD) data.
Polymorphic microsatellite markers for endangered spotted suslik, Spermophilus suslicus
Authors: GONDEK ALEKSANDRA , VERDUIJN MARIJE , WOLFF KIRSTEN
Published: February 2006

Spotted suslik Spermophilus suslicus is one of the most endangered mammal species in Poland. Over the last 50 years, it lost more than 90% of its populations and about 70% of its individuals. In order to establish a conservation and reintroduction program, the knowledge of population structure of the species is crucial. We have developed nine polymorphic microsatellite loci to analyse the population structure. Six of the primer sets also amplify polymorphic markers in the European suslik Spermophilus citellus.
Isolation and characterization of five dinucleotide microsatellite loci in the sandbar shark, Carcharhinus plumbeus
Authors: PORTNOY D. S. , MCDOWELL J. R. , THOMPSON K. , MUSICK J. A. , GRAVES J. E.
Published: February 2006

Five dinucleotide markers were isolated and optimized from a microsatellite‐enriched genomic library obtained from the sandbar shark, Carcharhinus plumbeus. Genotypic distributions of all markers were found to be in conformance with the expectations of Hardy–Weinberg equilibrium with four to 39 alleles present per locus. We amplified these loci in two female sharks and their litters. A maternal allele was recovered at each locus in all progeny indicating reliable amplification. More than two paternal alleles were recovered across both litters indicating genetic polyandry. Additionally, these markers were amplified across 10 carcharhiniform species to examine their utility in other studies.
The D category VI type 4 allele is prevalent in the Spanish population
Authors: Esteban Rosa , Montero Rosa , Flegel Willy A. , Wagner Franz F. , Subirana Laia , Parra Rafael , Ribera Anna , Nogués Núria
Published: February 2006

BACKGROUND:  The D category VI (DVI) is one of the clinically most important partial D. Three different molecular structures causing the DVI phenotype have been described.

STUDY DESIGN AND METHODS:  To determine the molecular basis of the DVI phenotype in the Spanish population, 20 DVI samples, previously detected in serologic screening, were examined by polymerase chain reaction with RHD exon–specific primers. Unexpected findings were further pursued by cDNA nucleotide sequencing.

RESULTS:  A novel pattern of RHD exon amplification was detected, which did not correspond to any of the previously described molecular structures. The cDNA sequence led to the identification of the new hybrid RHD‐Ce(3‐5)‐D allele. The origin of exon 2 is undeterminable, because the 5′ breakpoint was located within a region of RHD and RHCE identical sequence, which encompasses this exon. Sequencing of intron 5 allowed the 3′ breakpoint to be mapped between the sixth and seventh polymorphic sites. Serologically, the hybrid protein has a D epitope expression pattern identical to the previously described DVI phenotypes and an antigen density slightly lower than DVI type 3. The new DVI variant is linked to the DCe haplotype and expresses the low‐incidence BARC antigen.

CONCLUSION:  A novel structure causing the DVI phenotype, here named DVI type 4, has been characterized. This novel structure is the most frequent cause of DVI in Spain.
A high‐resolution, double‐labeling method for the study of in vivo red blood cell aging
Authors: Gifford Sean C. , Yoshida Tatsuro , Shevkoplyas Sergey S. , Bitensky Mark W.
Published: February 2006

BACKGROUND:  Red blood cell (RBC) senescence is a process that has received considerable study, yet remains poorly understood. This has been primarily due to the difficulty in isolating a RBC cohort of narrowly distributed, well‐defined age. Biotin labeling has previously been used to produce an identifiable cell cohort of known mean age; however, the variability of RBC age within the cohort is relatively large for most of its existence. Treatments typically employed on animal subjects to reduce this variability can perturb erythropoiesis and result in abnormal RBC aging.

STUDY DESIGN AND METHODS:  The objective of this study was to improve on the traditional in vivo biotinylation method by introducing a chemically distinct, second labeling step. In this case, digoxigenin was used to label cells 1 to 2 days before the injection of biotin.

RESULTS:  It was shown, in the rat, that two identifiable subpopulations of labeled RBCs can be followed over time: a broad, double‐labeled cohort and a narrow, single‐labeled cohort, the latter consisting of only those cells created between the first and second labeling steps. The utility of this technique was demonstrated by observing the age‐dependent exposure of phosphatidylserine in the single‐labeled RBCs.

CONCLUSION:  Its capacity to generate a cohort of narrowly distributed age, without the adverse effects associated with animal treatment, should make this a useful method for the study of RBC senescence.
Actinobacillus actinomycetemcomitans and Porphyromonas gingivalis subgingival presence, species‐specific serum immunoglobulin G antibody levels, and periodontitis disease recurrence
Authors: Rams T. E. , Listgarten M. A. , Slots J.
Published: February 2006

Background and Objective:  The biological and clinical effects of antibody against periodontal pathogenic bacteria are incompletely understood. This study evaluated the inter‐relationships among periodontal levels of cultivable Actinobacillus actinomycetemcomitans and Porphyromonas gingivalis, species‐specific serum immunoglobulin G (IgG) antibody levels, and periodontitis disease activity.

Material and Methods:  Forty‐three adults who had previously been treated for periodontitis and who also harbored cultivable A. actinomycetemcomitans or P. gingivalis were evaluated semiannually for clinical disease recurrence over a 36‐month period. Each patient provided subgingival microbial samples, for the recovery of A. actinomycetemcomitans and P. gingivalis, from the two deepest pockets in each dentition sextant. A. actinomycetemcomitans and P. gingivalis serum IgG antibody levels were assessed using enzyme‐linked immunosorbent assay (ELISA), together with whole‐cell sonicate extracts from A. actinomycetemcomitans serotypes a–c and P. gingivalis ATCC 33277. Data were analyzed using the Mantel–Haenszel chi‐square and Fisher exact two‐tailed tests.

Results:  Eighteen (60.0%) of 30 A. actinomycetemcomitans‐positive subjects, and 10 (76.9%) of 13 P. gingivalis‐positive subjects, exhibited recurrent periodontal breakdown within 36 months of periodontal therapy. Nineteen (67.9%) of the 28 patients with active periodontitis had A. actinomycetemcomitans or P. gingivalis serum antibody levels below designated threshold values. In comparison, 10 (66.7%) of 15 culture‐positive clinically stable subjects showed A. actinomycetemcomitans or P. gingivalis serum antibody levels above threshold values. The difference between specific antibody levels in periodontitis‐active and periodontitis‐stable patients was statistically significant (p = 0.032).

Conclusions:  Serum levels of IgG antibodies against A. actinomycetemcomitans or P. gingivalis in periodontitis‐stable patients were higher than those in patients with active periodontitis. The results suggest that elevated levels of IgG antibody against A. actinomycetemcomitans and P. gingivalis have a detectable protective effect against periodontal infections with these microorganisms.
Melatonin reduces apoptosis and necrosis induced by ischemia/reperfusion injury of the pancreas
Authors: Muñoz‐Casares Francisco C. , Padillo Francisco J. , Briceño Javier , Collado Juan A. , Muñoz‐Castañeda Juan R. , Ortega Rosa , Cruz Adolfo , Túnez Isaac , Montilla Pedro , Pera Carlos , Muntané Jordi
Published: February 2006

Abstract:  The pancreas is highly susceptible to the oxidative stress induced by ischemia/reperfusion (IR) injury leading to the generation of acute pancreatitis. Melatonin has been shown to be useful in the prevention of the damage by ischemia‐reperfusion in liver, brain, myocardium, gut and kidney. The aim of the study was to evaluate the cytoprotective properties of melatonin against injury induced by IR in pancreas. The obstruction of gastro‐duodenal and inferior splenic arteries induced pancreatic IR in male Wistar rats. Melatonin was intraperitoneally administered before or/and after IR injury. The animals were killed at 24 and 48 hr after reperfusion and there were evaluated parameters of oxidative stress (lipoperoxides, superoxide dismutase, catalase, glutathione peroxidase and reduced glutathione), glandular endocrine and exocrine function (lipase, amylase, insulin) and cell injury (apoptosis and necrosis). The IR induced a marked enhancement of oxidative stress and impaired pancreatic function. The histological analysis showed that IR induced acute pancreatitis with the accumulation of inflammatory infiltrate, disruption of tissue structure, cell necrosis and hemorrhage. Melatonin administration before or after pancreatic IR prevented all tissue markers of oxidative stress, biochemical and histological signs of apoptosis and necrosis, and restored glandular function. No histological signs of pancreatitis were observed 48 hr after reperfusion in 80% of the animals treated with melatonin, with only a mild edematous pancreatitis being observed in the remaining rats. Preventive or therapeutic administration of melatonin protected against the induction of oxidative stress and tissue injury, and restored cell function in experimental pancreatic IR in rats.
Synchronous granular cell tumor of the bladder, endometrial carcinoma and endometrial stromal sarcoma
Authors: KIYOZUKA Yasuhiko , YAMAMOTO Masashi , MATSUYAMA Tomohiko , MIKI Katsuaki , TSUKAMOTO Reiko , SHIMANO Naoto , TSUBURA Airo
Published: February 2006

We describe a very rare case of synchronous granular cell tumor of the bladder, endometrial carcinoma and endometrial stromal sarcoma. A 55‐year‐old woman with a 4‐month history of genital bleeding was cytologically diagnosed with endometrial carcinoma. Imaging studies suggested concomitant bladder tumor with the possibility of direct invasion from endometrial carcinoma. Total abdominal hysterectomy with bilateral salpingo‐oophorectomy and transurethral resection of bladder tumor was performed. The bladder tumor comprised polygonal cells with abundant eosinophilic, finely granular cytoplasm, separated by collagenous tissue. Neither nuclear pleomorphism nor tumor necrosis was found. Immunohistochemical expression of neural markers of neuron‐specific enolase and S‐100 allowed the diagnosis of granular cell tumor (GCT) of the bladder. Microscopic examination of endometrium revealed endometrioid adenocarcinoma with squamous differentiation (EAC). Ill‐defined nodular lesion comprising endometrial stromal sarcoma (ESS) was accidentally found in myometrium. Postoperatively, the patient underwent radiotherapy. This is the first well‐documented case of synchronous triple tumors comprising GCT of the bladder, uterine EAC and ESS.
Targeting epidermal growth factor receptor in lung cancer: Perspective from the Asia–Pacific region
Authors: LIU H Eugene , LIM Ken‐Hong , HUANG Ming‐Jer , HUANG Biing‐Shiun
Published: February 2006

The epidermal growth factor receptor (EGFR) is a receptor tyrosine kinase of the ErbB family that is frequently overexpressed in non‐small cell lung cancer (NSCLC), and has been identified as a novel therapeutic target for lung cancer. The development of small molecule EGFR‐tyrosine kinase inhibitors (TKI) such as gefitinib and erlotinib has resulted in paradigm shift in the treatment of advanced NSCLC. The impact of EGFR‐TKI in the treatment of NSCLC is even greater in Asia–Pacific region because one of the greatest clinical benefits of EGFR‐TKI has been seen in patients of East Asian ethnicity. The discovery of somatic mutations in EGFR‐tyrosine kinase domain has so far answered some, but not all, of the questions regarding the clinical response to EGFR‐TKI in NSCLC. In addition, other molecular profiles such as KRAS mutations have also been found to play an important role in EGFR targeted therapy. In this article, we review EGFR targeted therapy in NSCLC with the focus on perspective from the Asia–Pacific region.
Water quality and accelerated winter growth of European catfish using an enclosed recirculating system
Authors: David J. A.
Published: February 2006

Aquaculture of the European catfish Silurus glanis is impeded by the slow rate of growth at ambient water temperatures below 10°C, which are encountered during the winter months in many regions of Europe (such as central France). In an effort to increase water temperatures over this period, fish were held in an enclosed housing where the water quality was maintained using a low‐cost treatment plant. For comparison, some fish were held in a separate system that was not enclosed and where water treatment took place in an adjacent earth‐lined pond. Both systems were able to maintain good water quality during the winter months but the recirculating system achieved significantly higher water temperatures and rates of fish growth.
Cost‐effective survey of fish by the intensive netting of a linear canal in the Midlands (UK)
Authors: Smith P. A.
Published: February 2006

The performances of two micromesh nets, which were physically similar but differed in weight of leadline (i.e. 120 g/m2 vs. 250 g/m2), to estimate the numbers of four species of fish (roach, gudgeon, perch and bream) were investigated on 51 occasions. These two nets were found to capture fish longer than 25 mm. Capture efficiency was found to vary according to design of net, species and size of fish. Both nets usually produced a reduction in numbers of fish caught with successive removals, although the heavy leadlined net was more likely to cause a reduction in catch and in a constant manner than the light leadlined net. The accuracy of the heavy leadlined net to estimate a known number of roach ≥90 mm and gudgeon ≥90 mm was tested on two occasions. The known number was within the 95% confidence limits of the population estimate for both species, although the precision of the estimate for gudgeon was low at one site. The precision of the within‐site estimates was found to vary according to the type of net, the species and size class, and the number of removals. Overall, the heavy leadlined net was found to be more useful but required greater manpower. The implications of these findings for survey design are discussed.
Examination of the Stress Distribution in the Tip of a Pencil
Authors: Pogozelski E. , Cole D. , Wesley M.
Published: February 2006

The stresses within the tip of a pencil are examined theoretically, numerically, and experimentally to determine the position and orientation of the fracture surface. The von Mises stress is used to evaluate the impact of the normal and shear stresses due to compression, bending, torsion, and shear. The worst-case stress is shown to occur along the top edge of the inclined pencil point, where the normal stress is compressive. The resulting crack propagates diagonally downwards and towards the tip from this initial position, and is frequently observed to contain a cusp.
Rayleigh’s Quotient of Linear Piezoelectricity and Its Use in the Approximate Calculation of the Natural Frequencies of Piezoelectric Continua
Authors: Cupiał Piotr
Published: February 2006

The paper discusses an extension to the linear theory of piezoelectricity of the Rayleigh quotient used in the analysis of the properties and the approximate calculation of the natural frequencies of elastic continua. It is shown that for a piezoelectric continuum an infinite number of equivalent expressions can be obtained which generalize the classical Rayleigh quotient. The stationarity conditions of any of these quotients under additional constraints imposed by the Gauss equation of electrostatics and the prescribed natural electrical boundary condition are shown to result in the complete set of the governing equations of the free vibration problem of a piezoelectric continuum. The general results discussed in the paper are illustrated by the approximate calculation of the natural frequencies of a piezoelectric rod by the Rayleigh–Ritz method. Unlike in the case of elastic structures, no monotonic convergence of the approximate frequencies is guaranteed for a piezoelectric continuum, the property which can be explained using the introduced Rayleigh quotients.
Interaction of a Screw
Dislocation With an Arbitrary Shaped Elastic
Inhomogeneity
Authors: Wang Xu , Sudak L.
J.
Published: February 2006

In this paper, the interaction between a screw dislocation and an arbitrary shaped elastic inhomogeneity with different material properties than the surrounding matrix is investigated. The exact solution to this problem is derived by means of complex variable methods and Faber series expansion. Specifically, the conformal mapping function maps the matrix region surrounding the inhomogeneity onto the outside of a unit circle in the image plane, while the analytic function defined in the elastic inhomogeneity is expressed in terms of a Faber series expansion. Once the series form solution is obtained, the stress fields due to the screw dislocation can be obtained. Also the image force on the screw dislocation due to its interaction with the elastic inhomogeneity is derived. Three examples of a screw dislocation interacting with (1) an equilateral triangular inhomogeneity, (2) a square inhomogeneity, and (3) a five-pointed star-shaped inhomogeneity are presented to illustrate how the stiffness of the triangular, square or five-pointed star-shaped inhomogeneity can influence the mobility of the screw dislocation.
Energetics of Epitaxial Island Arrangements on Substrate Mesas
Authors: Machtay N. D. , Kukta R. V.
Published: February 2006

Self-assembly of strained epitaxial deposits (islands) grown on a substrate is a promising route to fabricate nanostructures of significance for electronic and optoelectronic devices. The challenge is to achieve specific island arrangements that are required for device functionality and high performance. This article investigates growth on a topographically patterned substrate as a means to control the arrangement of islands. By taking free energy to consist of elastic energy and surface energy, minimum energy configurations are calculated for islands on a raised substrate mesa. Configurations of one, two, and three islands at different positions on the mesa are considered to determine their relative energies as a function of mesa size, island size, mismatch strain between the island and substrate materials, surface energy, and elastic moduli. Insight is offered on the mechanisms responsible for certain physical observations such as a transition from the formation of multiple islands to a single island as mesa size is reduced.
Estimation of Internal Stress Profiles Using the Barkhausen Noise Effect—Application: Verification to the Homogeneity of the Shot Peening Process Performed on the Raceways of Aerospace Bearing Rings
Authors: Desvaux S. , Duquennoy M. , Ouaftouh M. , Gualandri J. , Ourak M.
Published: February 2006

In this paper, we present a nondestructive method based on the Barkhausen noise effect for estimating internal stress profiles, with the goal of controlling bearing raceways to determine the homogeneity of the shot peening process. Given the industrial imperative to characterize parts, our method concentrates on stress profiles in the first 60μm under the surface, in steps of 5 or 10μm. Our results show the efficient use of Barkhausen noise to estimate the residual stress profiles of bearing raceways. A mapping of the stress profiles measured by Barkhausen noise was completed for the entire width of an outer ring raceway. This study confirmed that it is possible to use Barkhausen noise to test the uniformity of the shot peening treatment and to inspect the homogeneity of surface and subsurface stresses on the bearing rings. The proposed method is rapid, well suited to industrial imperatives connected to on-line measurement, and easily adapted to the circular geometries of the bearing rings.
Hygrothermal Stresses in Unsymmetric Laminates Disturbed by Elliptical Holes
Authors: Hsieh M. C. , Hwu Chyanbin
Published: February 2006

Since the composite laminates are now in widespread use, many coupling phenomena within the composite laminates are widely focused in the world. One of those is the problem of stretching-bending coupling under hygrothermal environment. Because of the hygrothermal stress concentration, the understanding of hygrothermal effects on holes in laminates becomes important for the practical engineering design. However, due to mathematical infeasibility, most of the analytical solutions presented in literature are for two-dimensional problems or just for mechanical loading conditions, not for general composite laminates under hygrothermal environment. In order to establish a systematic analytical approach, in this study by extending the Stroh formalism for two-dimensional linear anisotropic elasticity and the Stroh-like formalism for coupled stretching-bending analysis of composite laminates, we develop an extended Stroh-like formalism for the coupled stretching-bending analysis under hygrothermal environment. By using the extended Stroh-like formalism developed in this paper, the explicit solutions for an unbounded laminate, symmetric or unsymmetric, disturbed by an elliptical hole subjected to uniform heat flow and moisture transfer in the x1-x2 plane or x3 direction are now obtained. With these solutions three typical numerical examples are illustrated and compared by ANSYS finite element software package.
Chaotic Phenomena Induced by the Fast Plastic Deformation of Metals During Cutting
Authors: Palmai Zoltan
Published: February 2006

In the present study the examination of chip formation is focused on the primary shear zone, which is divided into two layers, and the variation of shear stress and temperature in time are given by two mechanical balance equations and three energy equations. All the five evolution differential equations are autonomous and nonlinear. The material characteristics are determined by an exponential constitutive equation. The mathematical model is suitable for the qualitative description of different types of chips, such as continuous chips and periodic or aperiodic shear localized chips, which is demonstrated by the general structure and typical solutions of the equation system.
The Viscoelastic Fiber Composite with Nonlinear Interface
Authors: Xie Mayue , Levy Alan J.
Published: February 2006

Effective viscoelastic response of a unidirectional fiber composite with interfaces that may separate or slip according to uniform Needleman-type cohesive zones is analyzed. Previous work on the solitary elastic composite cylinder problem leads to a formulation for the mean response consisting of a stress-strain relation depending on the interface separation∕slip discontinuity together with an algebraic equation governing its evolution. Results for the fiber composite follow from the composite cylinders representation of a representative volume element (RVE) together with variational bounding. Here, the theory is extended to account for viscoelastic matrix response. For a solitary elastic fiber embedded in a cylindrical matrix which is an nth-order generalized Maxwell model in shear relaxation, a pair of nonlinear nth-order differential equations is obtained which governs the relaxation response through the time dependent stress and interface separation∕slip magnitude. When the matrix is an nth-order generalized Kelvin model in shear creep, a pair of nonlinear nth-order differential equations is obtained governing the creep response through the time dependent strain and interface separation∕slip magnitude. We appeal to the uniqueness of the Laplace transform and its inverse to show that these equations also apply to an RVE with the composite cylinders microstructure. For a matrix, which is a standard linear solid (n=2), the governing equations are analyzed in detail paying particular attention to issues of bifurcation of response. Results are obtained for transverse bulk response and antiplane shear response, while axial tension with related lateral Poisson contraction and transverse shear are discussed briefly. The paper concludes with an application of the theory to the analysis of stress relaxation in the pure torsion of a circular cylinder containing unidirectional fibers aligned parallel to the cylinder axis. For this problem, the redistribution of shear stress and interface slip throughout the cross section, and the movement of singular surfaces, are investigated for an interface model that allows for interface failure in shear mode.
Closed-Form Solution for an Antiplane Interface Crack between Two Dissimilar Magnetoelectroelastic Layers
Authors: Wang Bao-Lin , Mai Yiu-Wing
Published: February 2006

In recent years, ferroelectromagnetic laminated composites have aroused worldwide research interest. In this paper, we developed a closed-form solution for antiplane mechanical and in-plane electric and magnetic fields for a crack between two dissimilar magnetoelectroelastic layers of finite thickness. Explicit expressions for stresses, electric and magnetic fields, together with their intensity factors are obtained for the two extreme cases of an impermeable and a permeable crack. Solutions for some special cases, such as a homogeneous magnetoelectroelastic layer, two magnetoelectroelastic layers with opposite poling directions, and a piezoelectric layer bonded to a piezomagnetic layer are also obtained. Explicit relations between the field intensity factors and the energy release rates for the interface crack are provided.
Prediction of Falling Cylinder Through Air-Water-Sediment Columns
Authors: Chu Peter C. , Fan Chenwu
Published: February 2006

A falling rigid body through air, water, and sediment is investigated experimentally and theoretically. Two experiments were conducted to drop rigid cylinders with density ratio around 1.8 into shallow water (around 13 m deep) in the Monterey Bay (Exp-1) and into the Naval Postgraduate School’s swimming pool (Exp-2). During the experiments, we carefully observe cylinder track and burial depth while simultaneously taking gravity cores (in Exp-1). After analyzing the gravity cores, we obtain the bottom sediment density and shear strength profiles. The theoretical work includes the development of a 3D rigid body impact burial prediction model (IMPACT35) that contains three components: triple coordinate transform and hydrodynamics of a falling rigid object in a single medium (air, water, or sediment) and in multiple media (air-water and water-sediment interfaces). The model predicts the rigid body’s trajectory in the water column and burial depth and orientation in the sediment. The experimental data (burial depth, sediment density, and shear strength) show the capability of IMPACT35 in predicting the cylinder’s trajectory and orientation in a water column and burial depth and orientation in sediment.
Coupling of Extension and Twist in Single-Walled Carbon Nanotubes
Authors: Chandraseker Karthick , Mukherjee Subrata
Published: February 2006

This paper presents a study of the deformation behavior of single-walled carbon nanotubes (SWNTs) subjected to extension and twist. The interatomic force description is provided by the Tersoff-Brenner potential for carbon. The rolling of a flat graphene sheet into a SWNT is first simulated by minimizing the energy per atom, the end result being the configuration of an undeformed SWNT. The Cauchy-Born rule is then used to connect the atomistic and continuum descriptions of the deformation of SWNTs, and leads to a multilength scale mechanics framework for simulating deformation of SWNTs under applied loads. Coupled extension and twist of SWNTs is considered next. As an alternative to the Cauchy-Born rule for coupled extension-twist problems, a direct map is formulated. Analytic expressions are derived for the deformed bond lengths using the Cauchy-Born rule and the direct map for this class of deformations. Numerical results are presented for kinematic coupling, for imposed extension and imposed twist problems, using the Cauchy-Born rule as well as the direct map, for representative chiral, armchair and zig-zag SWNTs. Results from both these approaches are carefully compared.
Discussion: “Damage Modeling in Random Short Glass Fiber Reinforced Composites Including Permanent Strain and Unilateral Effect” (Mir, H., Fafard, M., Bissonnette, B., and Dano, M. L., 2005, ASME J. Appl. Mech., 72, pp. 249–258)
Authors: Challamel Noël , Lanos Christophe , Casandjian Charles
Published: February 2006

The paper of Mir et al. [ASME J. Appl. Mech., 72, pp. 249–258 (2005)] analyzes the deformation behavior of random short glass fiber composites using a continuum damage mechanics model incorporating permanent strain and unilateral effect. Unilateral effect is a difficult topic [see, for instance, J. L. Chaboche, Int. J. Damage Mech., 2, pp. 311–329 (1993)] and it seems to us that the model of Mir et al. still raises some questions.
Enterococcus gallinarum
N04-0414 Harbors a VanD-Type Vancomycin Resistance Operon and Does Not Contain a
d
-Alanine:
d
-Alanine 2 (
ddl2
) Gene
Authors: Boyd David A. , Miller Mark A. , Mulvey Michael R.
Published: February 2006

Enterococcus gallinarum
N04-0414 (MIC for vancomycin, 256 μg/ml) harbored a
vanD
-type vancomycin resistance operon as well as the intrinsic
vanC1
operon. The
d
-Ala:
d
-Ala ligase 2 gene (
ddl2
) was not present in the strain, though it is found downstream of the
vanS
gene from the
vanC
operon in
E. gallinarum
ATCC 49573 and 19 other
E. gallinarum
strains tested.
Molecular Characterization of Isoniazid Resistance in
Mycobacterium tuberculosis
: Identification of a Novel Mutation in
inhA
Authors: Leung E. T. Y. , Ho P. L. , Yuen K. Y. , Woo W. L. , Lam T. H. , Kao R. Y. , Seto W. H. , Yam W. C.
Published: February 2006

Multiplex allele-specific PCRs detecting
katG
codon 315 and
mabA
(bp −15) mutations could specifically identify 77.5% of isoniazid-resistant
Mycobacterium tuberculosis
strains in the South China region. One clinical isolate harboring InhA Ile194Thr was characterized to show strong association with isoniazid resistance in
Mycobacterium tuberculosis
.
Detection of Methicillin-Resistant
Staphylococcus aureus
Strains Resistant to Multiple Antibiotics and Carrying the Panton-Valentine Leukocidin Genes in an Algiers Hospital
Authors: Ramdani-Bouguessa Nadjia , Bes Michèle , Meugnier Hélène , Forey Françoise , Reverdy Marie-Elisabeth , Lina Gerard , Vandenesch François , Tazir Mohamed , Etienne Jerome
Published: February 2006

Forty-five Panton-Valentine leukocidin (PVL)-positive, methicillin-resistant
Staphylococcus aureus
strains were isolated in Algeria between 2003 and 2004; 18 isolates were isolated in the community and 27 in a hospital. Five PVL-positive hospital isolates were resistant to multiple antibiotics, including ofloxacin and gentamicin for three isolates.
In Vitro Development of Resistance to Human Immunodeficiency Virus Protease Inhibitor GW640385
Authors: Yates P. J. , Hazen R. , St. Clair M. , Boone L. , Tisdale M. , Elston R. C.
Published: February 2006

Development of in vitro resistance to GW640385, a new human immunodeficiency virus type 1 protease inhibitor, was studied. Variants characterized included one with <4-fold resistance and amino acid substitutions Q58E/A71V (protease) and P452K (Gag) and one with >50-fold resistance and amino acid substitutions L10F/G16E/E21K/A28S/M46I/F53L/A71V (protease) and L449F/P453T (Gag). The A28S substitution substantially reduced replication capacity.
Roles of Cellular Respiration, Cg
CDR1
, and Cg
CDR2
in
Candida glabrata
Resistance to Histatin 5
Authors: Helmerhorst Eva J. , Venuleo Caterina , Sanglard Dominique , Oppenheim Frank G.
Published: February 2006

Histatin 5, a human salivary protein with broad-spectrum antifungal activity, is remarkably ineffective against
Candida glabrata
. Fluconazole resistance in this fungus is due in most cases to upregulation of Cg
CDR
efflux pumps. We investigated whether the distinct resistance of
C. glabrata
to histatin 5 is related to similar mechanisms.
NorC, a New Efflux Pump Regulated by MgrA of
Staphylococcus aureus
Authors: Truong-Bolduc Que Chi , Strahilevitz Jacob , Hooper David C.
Published: February 2006

NorC, a new efflux pump, like NorB, contributes to quinolone resistance that includes resistance to moxifloxacin and sparfloxacin in
Staphylococcus aureus. norC
expression, like that of
norB
and
tet38
, is negatively regulated by MgrA, and overexpression of both
norC
and
norB
contributes to the quinolone resistance phenotype of an
mgrA
mutant.
Evaluation of Disk Diffusion Method for Determining Posaconazole Susceptibility of Filamentous Fungi: Comparison with CLSI Broth Microdilution Method
Authors: López-Oviedo E. , Aller A. I. , Martín C. , Castro C. , Ramirez M. , Pemán J. M. , Cantón E. , Almeida C. , Martín-Mazuelos E.
Published: February 2006

The disk diffusion method was evaluated for determining posaconazole susceptibility against 78 strains of molds using two culture media in comparison with the CLSI (Clinical Laboratory Standards Institute) broth microdilution method (M38-A). A significant correlation between disk diffusion and microdilution methods was observed with both culture media.
Activities of Tizoxanide and Nitazoxanide Compared to Those of Five Other Thiazolides and Three Other Agents against Anaerobic Species
Authors: Pankuch Glenn A. , Appelbaum Peter C.
Published: February 2006

Agar dilution was used, and MICs of metronidazole, tizoxanide, nitazoxanide, denitrotizoxanide, RM 4803, RM 4807, RM 4809, RM 4819, amoxicillin-clavulanate, and clindamycin were measured against 412 anaerobes. Nitazoxanide, tizoxanide, RM 4807, and RM 4809 were active against all groups, except for gram-positive non-spore-forming rods with 50% minimum inhibitory concentrations (when the latter were excluded) of 1 to 2 μg/ml and 90% minimum inhibitory concentrations of 4 to 8 μg/ml, respectively. Metronidazole MICs were usually lower against all groups except clostridia.
Lack of Evidence for In Vivo Transformation of Zidovudine Triphosphate to Stavudine Triphosphate in Human Immunodeficiency Virus-Infected Patients
Authors: Meléndez Margarita , Blanco Raúl , Delgado Wilfredo , García Rosario , Santana Jorge , García Hermes , Rosario Osvaldo , Rodríguez José F.
Published: February 2006

The in vivo and in vitro determination of significant intracellular stavudine (d4T) triphosphate (d4TTP) concentrations in human immunodeficiency virus (HIV)-infected subjects and NS-1 cells treated with zidovudine (ZDV) has recently been reported. This study was conducted to corroborate these findings with in vivo samples from HIV-infected subjects taking ZDV and in vitro CEM
SS
cells incubated with different ZDV concentrations. Previously, we have reported on our validated high-performance liquid chromatography coupled with tandem mass spectrometry methodology for the simultaneous determination of d4TTP, lamivudine triphosphate, and ZDV triphosphate (ZDVTP) concentrations. Using this methodology, we monitored the d4TTP concentration in more than 100 samples from HIV-infected subjects treated with d4T. In addition, we simultaneously monitored the concentrations of d4TTP and ZDVTP in more than 500 samples from HIV-infected individuals who were taking ZDV. Finally, we performed in vitro studies by incubating CEM
SS
cells with 10 μM, 50 μM, and 100 μM ZDV and monitored the formation of d4TTP at 24 and 48 h. We could measure d4TTP concentrations from HIV-infected individuals with a limit of quantitation (LOQ) of 2.7 fmol/10
6
cells (total injection, 54 fmol). In the in vivo studies, we measured the d4TTP concentrations among patients receiving d4T treatment, but the samples from patients taking ZDV did not provide d4TTP concentrations above the LOQ. Furthermore, in vitro samples did not produce any signal for d4TTP, despite the detection of substantial ZDVTP concentrations in CEM
SS
cells. Thus, contrary to the previous report, we found no evidence for the in vivo or in vitro transformation of ZDVTP to d4TTP in HIV-infected subjects or CEM
SS
cells.
Structural Correlates of Antibacterial and Membrane-Permeabilizing Activities in Acylpolyamines
Authors: Balakrishna Rajalakshmi , Wood Stewart J. , Nguyen Thuan B. , Miller Kelly A. , Suresh Kumar E. V. K. , Datta Apurba , David Sunil A.
Published: February 2006

A homologous series of mono- and bis-acyl polyamines with varying acyl chain lengths originally synthesized for the purpose of sequestering lipopolysaccharide were evaluated for antimicrobial activity to test the hypothesis that these bis-cationic amphipathic compounds may also bind to and permeabilize intact gram-negative bacterial membranes. Some compounds were found to possess significant antimicrobial activity, mediated via permeabilization of bacterial membranes. Structure-activity relationship studies revealed a strong dependence of the acyl chain length on antimicrobial potency and permeabilization activity. Homologated spermine, bis-acylated with C8or C9chains, was found to profoundly sensitizeEscherichia colito hydrophobic antibiotics such as rifampin. Nonspecific cytotoxicity is a potential drawback of these membranophilic compounds. However, the surface activity of these cationic amphipaths is strongly attenuated under physiological conditions via binding to serum albumin. Significant antibacterial activity is still retained in the presence of physiological concentrations of human serum albumin, suggesting that these compounds may serve as leads in the development of novel adjuncts to conventional antimicrobial chemotherapy.
Pharmacokinetics of Telbivudine following Oral Administration of Escalating Single and Multiple Doses in Patients with Chronic Hepatitis B Virus Infection: Pharmacodynamic Implications
Authors: Zhou Xiao-Jian , Lim Seng-Gee , Lloyd Deborah M. , Chao George C. , Brown Nathaniel A. , Lai Ching-Lung
Published: February 2006

The pharmacokinetics of telbivudine were evaluated in adult patients with chronic hepatitis B virus (HBV) infection following once-daily oral administration at escalating doses of 25, 50, 100, 200, 400, and 800 mg/day for 4 weeks. Telbivudine was rapidly absorbed after oral administration, with the median times
T
max
to the maximum plasma concentration (
C
max
) ranging from 0.8 to 3.0 h postdosing across cohorts. Single-dose and steady-state maximum
C
max
s and the areas under the plasma concentration-time curve from time zero to time
t
(AUC

0-
t

s) increased proportionally with dose. At steady-state, the values of
C
max
and AUC

0-
t

were higher than those obtained after the administration of a single dose, indicative of a slight accumulation, with the ratios of the steady-state value to the value after the administration of a single dose ranging from 1.14 to 1.49 for
C
max
and from 1.40 to 1.70 for AUC

0-
t

. While the elimination of telbivudine from plasma was apparently monophasic over the 8-h sampling period, the substantial steady-state trough plasma levels observed in the groups receiving doses of 100 to 800 mg were clearly indicative of the presence of a second slower elimination phase, with the mean estimated half-lives ranging from 29.5 to 41.3 h by compartmental modeling analysis. Pharmacokinetic and pharmacodynamic analyses by using maximum-effect modeling established a quantitative relationship between a reduction in serum HBV DNA levels and parameters of drug exposure, in particular, the steady-state
C
max
and AUC

0-
t

. In summary, this study showed that telbivudine exhibits dose-proportional plasma pharmacokinetics with sustained steady-state drug exposure and exposure-related antiviral activity, supporting the need for further clinical studies by use of a once-daily regimen in patients with chronic HBV infection.
Interlaboratory Comparison of PCR-Based Methods for Detection of Penicillin G Susceptibility in
Neisseria meningitidis
Authors: Taha Muhamed-Kheir , Zarantonelli Maria Leticia , Neri Arianna , Enriquez Rocío , Vázquez Julio A. , Stefanelli Paola
Published: February 2006

We carried out a study for the nonculture detection of susceptibility of
Neisseria meningitis
to penicillin G in three laboratories of the European Monitoring Group on Meningococci (EMGM). Thirteen clinical samples (cerebrospinal fluids) and corresponding bacterial isolates from 13 cases of invasive meningococcal infection were distributed to the three laboratories. The MICs of penicillin G were determined for the isolates. Each laboratory used an “in-house” PCR-based method to determine alterations to the
penA
gene, which is associated with a reduced susceptibility to penicillin G. Nucleotide sequences from the 3′ end of the
penA
gene were also determined. We observed a good correlation between genotyping of
penA
and the phenotypic determination (MIC) of susceptibility to penicillin G. The results obtained by the three methods for
penA
in the samples correlated very well with those obtained in bacterial isolates and with sequence data. The kappa coefficient that was used to estimate the level of agreement between genotypic results varied between 0.65 and 1, indicating a good agreement. This suggests that genotyping can predict susceptibility of
N. meningitidis
to penicillin G. These data strongly suggest that genotyping of
penA
should be used to determine meningococcal susceptibility to penicillin G in culture-negative cases. Although the nucleotide sequence of
penA
may be the gold standard in genotyping of
penA
, the less expensive PCR-based approach reported in this study may be quicker when a large number of isolates and clinical samples need to be tested.
Effect of Efflux on Telithromycin and Macrolide Susceptibility in
Haemophilus influenzae
Authors: Bogdanovich Tatiana , Bozdogan Bülent , Appelbaum Peter C.
Published: February 2006

This study investigated the presence of telithromycin and azithromycin efflux in 58 clinical strains of
Haemophilus influenzae
with various susceptibilities to macrolides, azalides, and ketolides. Efflux pumps were studied by measuring accumulation of radioactive [
3
H]telithromycin and [
N
-methyl-
3
H]azithromycin in the presence and absence of carbonyl
m
-chlorophenylhydrazone (CCCP), a protonophore. In 17 strains for which the telithromycin MICs were 0.06 to 0.5 μg/ml (azithromycin MICs, ≤0.06 to 0.125 μg/ml; clarithromycin MICs, ≤0.06 to 2 μg/ml), telithromycin and azithromycin accumulations were high without CCCP and not affected by its addition, which indicates absence of efflux. In 22 strains for which the telithromycin MICs were 0.25 to 4 μg/ml (azithromycin MICs, 0.25 to 1 μg/ml; clarithromycin MICs, 1 to 8 μg/ml), initially low levels of telithromycin accumulation became higher after addition of CCCP, indicating a functioning efflux pump. Nineteen strains for which the telithromycin MICs were ≥2 μg/ml had efflux as well as various mutations in ribosomal proteins L4, L22, and/or 23S rRNA (domains II and V). Of these 19 strains, the telithromycin MICs (≥8 μg/ml) for 17 of them were significantly raised (azithromycin, MICs 4 to >32 μg/ml; clarithromycin MICs, 8 to >32 μg/ml). From these results we conclude that telithromycin efflux with or without additional ribosomal alterations is present in all
H. influenzae
strains, except for those for which the telithromycin MICs were very low.