bluuebunny/crossref_metadata_2025 huggingface dataset:
Analysis of a Unique Interaction between the Complement Regulatory Protein Factor H and the Periodontal PathogenTreponema denticola
Authors: McDowell John V. , Huang Bernice , Fenno J. Christopher , Marconi Richard T.
Published: February 2009

Treponema denticola, a spirochete associated with periodontitis, is abundant at the leading edge of subgingival plaque, where it interacts with gingival epithelia.T. denticolaproduces a number of virulence factors, including dentilisin, a protease which is cytopathic to host cells, and FhbB, a uniqueT. denticolalipoprotein that binds complement regulatory proteins. Earlier analyses suggested that FhbB specifically bound to factor H (FH)-like protein 1 (FHL-1). However, by using dentilisin-deficient mutants ofT. denticola, we found thatT. denticolapreferentially binds FH and not FHL-1, and that FH is then cleaved by dentilisin to yield an FH subfragment of ∼50 kDa. FH bound to dentilisin-deficient mutants but was not cleaved and retained its ability to serve as a cofactor for factor I in the cleavage of C3b. To assess the molecular basis of the interaction of FhbB with FH, mutational analyses were conducted. Replacement of specific residues in widely separated domains of FhbB and disruption of a central alpha helix with coiled-coil formation probability attenuated or eliminated FH binding. The data presented here are the first to demonstrate the retention at the cell surface of a proteolytic cleavage product of FH. The precise role of this FH fragment in the host-pathogen interaction remains to be determined.
Development of Multiple-Locus Variable-Number Tandem-Repeat Analysis for Molecular Typing of
Mycoplasma pneumoniae
Authors: Dégrange S. , Cazanave C. , Charron A. , Renaudin H. , Bébéar C. , Bébéar C. M.
Published: February 2009

In this study we report on the development of a multilocus variable-number tandem-repeat (VNTR) analysis (MLVA) method for the molecular typing of
Mycoplasma pneumoniae
. The genomic content of
M. pneumoniae
M129 was analyzed for VNTRs, and 5 of the 17 VNTRs identified were selected for use in an MLVA assay. The method was based on a GeneScan analysis of VNTR loci labeled with fluorescent dyes by multiplex PCR and capillary electrophoresis. This approach was applied to a collection of 265 isolates from various European countries, Japan, and Tunisia; and 26 distinct VNTR types were found. The VNTR assay was compared to the P1 adhesin PCR-restriction fragment length polymorphism (RFLP) typing method and showed a far better resolution than the P1 PCR-RFLP method. The discriminatory power of MLVA (Hunter-Gaston diversity index [HGDI], 0.915) for the 265 isolates was significantly higher than that of the P1 PCR-RFLP method (HGDI, 0.511). However, there was a correlation between the typing results obtained by MLVA and the P1 gene PCR-RFLP method. The potential value of MLVA of
M. pneumoniae
as an epidemiological tool is discussed, and the use of the VNTR markers in further investigations of the potential use of MLVA in outbreaks of
M. pneumoniae
infections is proposed.
Using a Commercial DiversiLab Semiautomated Repetitive Sequence-Based PCR Typing Technique for Identification of
Escherichia coli
Clone ST131 Producing CTX-M-15
Authors: Pitout Johann D. D. , Campbell Lorraine , Church Deirdre L. , Wang Pauline W. , Guttman David S. , Gregson Daniel B.
Published: February 2009

A study was designed to evaluate the ability of the DiversiLab fingerprinting kit, a type of repetitive element PCR (rep-PCR), to identify
Escherichia coli
clone ST131 producing β-lactamase CTX-M-15. A set of 53 nonduplicate isolates of extended-spectrum β-lactamase-producing
E. coli
underwent rep-PCR, pulsed-field gel electrophoresis, and multilocus sequence typing. The DiversiLab system successfully identified
E. coli
clone ST131 producing CTX-M-15 and provides a simple standardized typing protocol for monitoring the spread of this clone.
Some techniques for finite element analysis of embankments on soft ground
Authors: Chai J.C. , Bergado D.T.
Published: February 2009

The accuracy of finite element results depends on the numerical models and the parameters used as well as the numerical techniques adopted. Three aspects of modelling the behavior of embankment on soft ground are discussed in this technical note: (i) simulating the actual construction process, (ii) modelling the soft ground permeability variation during the loading and consolidation process, and (iii) selecting proper soil–reinforcement interface properties according to the relative displacement pattern of the upper and lower interface elements placed between the soil and reinforcement in the case of a reinforced embankment. The significance of these factors on the performance of the embankment on soft ground is demonstrated by case studies. Key words : finite element method, loading, permeability, reinforced soil.
On the exploitation of loop-level parallelism in embedded applications
Authors: Kejariwal Arun , Veidenbaum Alexander V. , Nicolau Alexandru , Girkar Milind , Tian Xinmin , Saito Hideki
Published: February 2009

Advances in the silicon technology have enabled increasing support for hardware parallelism in embedded processors. Vector units, multiple processors/cores, multithreading, special-purpose accelerators such as DSPs or cryptographic engines, or a combination of the above have appeared in a number of processors. They serve to address the increasing performance requirements of modern embedded applications. To what extent the available hardware parallelism can be exploited is directly dependent on the amount of parallelism inherent in the given application and the congruence between the granularity of hardware and application parallelism. This paper discusses how loop-level parallelism in embedded applications can be exploited in hardware and software. Specifically, it evaluates the efficacy of automatic loop parallelization and the performance potential of different types of parallelism, viz., true thread-level parallelism (TLP), speculative thread-level parallelism and vector parallelism, when executing loops. Additionally, it discusses the interaction between parallelization and vectorization. Applications from both the industry-standard EEMBC®,11.1, EEMBC 2.0 and the academic MiBench embedded benchmark suites are analyzed using the Intel®2C compiler. The results show the performance that can be achieved today on real hardware and using a production compiler, provide upper bounds on the performance potential of the different types of thread-level parallelism, and point out a number of issues that need to be addressed to improve performance. The latter include parallelization of libraries such as libc and design of parallel algorithms to allow maximal exploitation of parallelism. The results also point to the need for developing new benchmark suites more suitable to parallel compilation and execution.

1Other names and brands may be claimed as the property of others.

2Intel is a trademark of Intel Corporation or its subsidiaries in the United States and other countries.
Optimal message-driven implementations of omega with mute processes
Authors: Biely Martin , Widder Josef
Published: February 2009

We investigate the complexity of algorithms in message-driven models. In such models, events in the computation can only be caused by message receptions, but not by the passage of time. Hutle and Widder [2005a] have shown that there is no deterministic message-driven self-stabilizing implementation of the eventually strong failure detector and thus Ω in systems with uncertainty in message delays and channels of unknown capacity using only bounded space. Under stronger assumptions it was shown that even the eventually perfect failure detector can be implemented in message-driven systems consisting of at least
f
+ 2 processes (
f
being the upper bound on the number of processes that crash during an execution).

In this article we show that
f
+ 2 is in fact a lower bound in message-driven systems, even if nonstabilizing algorithms are considered. This contrasts time-driven models where
f
+ 1 is sufficient for failure detector implementations.

Moreover, we investigate algorithms where not all processes send message, that is, are active, but some (in a predetermined set) remain passive. Here, we show that the
f
+ 2 processes required for message-driven systems must be active, while in time-driven systems it suffices that
f
processes are active.

We also provide message-driven implementations of Ω. Our algorithms are efficient in the sense that not all processes have to send messages forever, which is an improvement to previous message-driven failure detector implementations.
Self-stabilizing philosophers with generic conflicts
Authors: Danturi Praveen , Nesterenko Mikhail , Tixeuil Sébastien
Published: February 2009

We generalize the classic dining philosophers problem to separate the conflict and communication neighbors of each process. Communication neighbors may directly exchange information while conflict neighbors compete for the access to the exclusive critical section of code. This generalization is motivated by a number of practical problems in distributed systems including problems in wireless sensor networks. We present a self-stabilizing deterministic algorithm—
GDP
that solves this generalized problem. Our algorithm is terminating. We formally prove
GDP
correct and evaluate its performance. We extend the algorithm to handle a similarly generalized drinking philosophers and the committee coordination problem. We describe how
GDP
can be implemented in wireless sensor networks and demonstrate that this implementation does not jeopardize its correctness or termination properties.
Using eventually consistent compasses to gather memory-less mobile robots with limited visibility
Authors: Souissi Samia , Défago Xavier , Yamashita Masafumi
Published: February 2009

Reaching agreement among a set of mobile robots is one of the most fundamental issues in distributed robotic systems. This problem is often illustrated by the gathering problem, where the robots must self-organize and meet at some location not determined in advance, and without the help of some global coordinate system. While very simple to express, this problem has the advantage of retaining the inherent difficulty of agreement, namely the question of breaking symmetry between robots. In previous works, it has been proved that the gathering problem is solvable in asynchronous model with oblivious (i.e., memory-less) robots and limited visibility, as long as the robots share the knowledge of some direction, as provided by a compass. However, the problem has no solution in the semi-synchronous model when robots do not share a compass, or when they cannot detect multiplicity.

In this article, we define a model in which compasses may be unreliable, and study the solvability of gathering oblivious mobile robots with limited visibility in the semi-synchronous model. In particular, we give an algorithm that solves the problem in finite time in a system where compasses are unstable for some arbitrary long periods, provided that they stabilize eventually. In addition, we show that our algorithm solves the gathering problem for at most three robots in the asynchronous model. Our algorithm is intrinsically self-stabilizing.
Cooperative node localization using nonlinear data projection
Authors: Li Li , Kunz Thomas
Published: February 2009

Cooperative node localization schemes that employ nonlinear data reduction often deliver higher network node position accuracy compared to many other approaches. Other advantages of such algorithms are that they require only a minimum number of anchor nodes (if we require absolute locations) and that they can be applied under both range-based and range-free conditions. This article presents a novel cooperative node localization scheme, applying an efficient neural network nonlinear projection method called Curvilinear Component Analysis (CCA). A thorough comparative performance study of the proposed scheme in different mission-critical operational network scenarios is conducted. Compared with another leading cooperative node localization algorithm, MDS-MAP, which employs Multi-Dimensional Scaling (MDS), the proposed CCA-MAP approach significantly improves position estimate accuracy in many of the scenarios. We also propose a new local edge model for range-free distance matrix approximation that considerably enhances the performance for both MDS-MAP and CCA-MAP in certain irregular network configurations which are very challenging for node positioning.
Design and evaluation of a hybrid sensor network for cane toad monitoring
Authors: Hu Wen , Bulusu Nirupama , Chou Chun Tung , Jha Sanjay , Taylor Andrew , Tran Van Nghia
Published: February 2009

This article investigates a wireless acoustic sensor network application—monitoring amphibian populations in the monsoonal woodlands of northern Australia. Our goal is to use automatic recognition of animal vocalizations to census the populations of native frogs and the invasive introduced species, the cane toad. This is a challenging application because it requires high frequency acoustic sampling, complex signal processing, wide area sensing coverage and long-lived unattended operation.

We set up two prototypes of wireless sensor networks that recognize vocalizations of up to ninth frog species found in northern Australia. Our first prototype consists of only resource-rich Stargate devices. Our second prototype is more complex and consists of a hybrid mixture of Stargates and inexpensive, resource-poor Mica2 devices operating in concert. In the hybrid system, the Mica2s are used to collect acoustic samples, and expand the sensor network coverage. The Stargates are used for resource-intensive tasks such as fast Fourier transforms (FFTs) and machine learning.

The hybrid system incorporates four algorithms designed to account for the sampling, processing, energy, and communication bottlenecks of the Mica2s (1) high frequency sampling, (2) thresholding and noise reduction, to reduce data transmission by up to 90%, (3) sampling scheduling, which exploits the sensor network redundancy to increase the effective sample processing rate, and (4) harvesting-aware energy management, which exploits sensor energy harvesting capabilities to extend the system lifetime.

Our evaluation shows the performance of our systems over a range of scenarios, and demonstrate that the feasibility and benefits of a hybrid systems approach justify the additional system complexity.
Energy-efficient link-layer jamming attacks against wireless sensor network MAC protocols
Authors: Law Yee Wei , Palaniswami Marimuthu , Hoesel Lodewijk Van , Doumen Jeroen , Hartel Pieter , Havinga Paul
Published: February 2009

A typical wireless sensor node has little protection against radio jamming. The situation becomes worse if energy-efficient jamming can be achieved by exploiting knowledge of the data link layer. Encrypting the packets may help to prevent the jammer from taking actions based on the content of the packets, but the temporal arrangement of the packets induced by the nature of the protocol might unravel patterns that the jammer can take advantage of, even when the packets are encrypted.

By looking at the packet interarrival times in three representative MAC protocols, S-MAC, LMAC, and B-MAC, we derive several jamming attacks that allow the jammer to jam S-MAC, LMAC, and B-MAC energy efficiently. The jamming attacks are based on realistic assumptions. The algorithms are described in detail and simulated. The effectiveness and efficiency of the attacks are examined. In addition, we validate our simulation model by comparing its results with measurements obtained from actual implementation on our sensor node prototypes. We show that it takes little effort to implement such effective jammers, making them a realistic threat.

Careful analysis of other protocols belonging to the respective categories of S-MAC, LMAC, and B-MAC reveals that those protocols are, to some extent, also susceptible to our attacks. The result of this investigation provides new insights into the security considerations of MAC protocols.
Localization and routing in sensor networks by local angle information
Authors: Bruck Jehoshua , Gao Jie , Jiang Anxiao (Andrew)
Published: February 2009

Location information is useful both for network organization and for sensor data integrity. In this article, we study the anchor-free 2D localization problem by using local angle measurements. We prove that given a unit disk graph and the angles between adjacent edges, it is NP-hard to find a valid embedding in the plane such that neighboring nodes are within distance 1 from each other and non-neighboring nodes are at least distance √2/2 away. Despite the negative results, however, we can find a planar spanner of a unit disk graph by using only local angles. The planar spanner can be used to generate a set of virtual coordinates that enable efficient and local routing schemes such as geographical routing or approximate shortest path routing. We also proposed a practical anchor-free embedding scheme by solving a linear program. We show by simulation that it gives both a good local embedding, with neighboring nodes embedded close and non-neighboring nodes far away, and a satisfactory global view such that geographical routing and approximate shortest path routing on the embedded graph are almost identical to those on the original (true) embedding.
Variable radii connected sensor cover in sensor networks
Authors: Zhou Zongheng , Das Samir R. , Gupta Himanshu
Published: February 2009

One of the useful approaches to exploit redundancy in a sensor network is to keep active only a small subset of sensors that are sufficient to cover the region required to be monitored. The set of active sensors should also form a connected communication graph, so that they can autonomously respond to application queries and/or tasks. Such a set of active sensors is known as a connected sensor cover, and the problem of selecting a minimum connected sensor cover has been well studied when the transmission radius and sensing radius of each sensor is fixed. In this article, we address the problem of selecting a minimum energy-cost connected sensor cover, when each sensor node can vary its sensing and transmission radius; larger sensing or transmission radius entails higher energy cost.

For the aforesaid problem, we design various centralized and distributed algorithms, and compare their performance through extensive experiments. One of the designed centralized algorithms (called CGA) is shown to perform within an
O
(log
n
) factor of the optimal solution, where
n
is the size of the network. We have also designed a localized algorithm based on Voronoi diagrams which is empirically shown to perform very close to CGA and, due to its communication-efficiency, results in significantly prolonging the network lifetime. We also extend the aforementioned algorithms to incorporate fault tolerance. In particular, we show how to extend the algorithms to address the minimum energy-cost connected sensor
k
-cover problem, in which every point in the query region needs to be covered by at least
k
distinct active sensors. The CGA preserves the approximation bound in this case. We also propose a localized topology control scheme to preserve
k
-connectivity, and use it to extend the Voronoi-based approach to computing a minimum energy-cost
k
1
-connected
k
2
-cover. We study the performance of our proposed algorithms through extensive simulations.
Achieving long-term surveillance in VigilNet
Authors: Vicaire Pascal , He Tian , Cao Qing , Yan Ting , Zhou Gang , Gu Lin , Luo Liqian , Stoleru Radu , Stankovic John A. , Abdelzaher Tarek F.
Published: February 2009

Energy efficiency is a fundamental issue for outdoor sensor network systems. This article presents the design and implementation of multidimensional power management strategies in VigilNet, a major recent effort to support long-term surveillance using power-constrained sensor devices. A novel tripwire service is integrated with an effective sentry and duty cycle scheduling in order to increase the system lifetime, collaboratively. The tripwire service partitions a network into distinct, nonoverlapping sections and allows each section to be scheduled independently. Sentry scheduling selects a subset of nodes, the sentries, which are turned on while the remaining nodes save energy. Duty cycle scheduling allows the active sentries themselves to be turned on and off, further lowering the average power draw. The multidimensional power management strategies proposed in this article were fully implemented within a real sensor network system using the XSM platform. We evaluate key system parameters using a network of 200 XSM nodes in an outdoor environment, and an analytical probabilistic model. We evaluate network lifetime using a simulation of a 10,000-node network that uses measured XSM power values. These evaluations demonstrate the effectiveness of our integrated approach and identify a set of lessons and guidelines, useful for the future development of energy-efficient sensor systems. One of the key results indicates that the combination of the three presented power management techniques is able to increase the lifetime of a realistic network from 4 days to 200 days.
Generalizing motion edits with Gaussian processes
Authors: Ikemoto Leslie , Arikan Okan , Forsyth David
Published: February 2009

One way that artists create compelling character animations is by manipulating details of a character's motion. This process is expensive and repetitive. We show that we can make such motion editing more efficient by generalizing the edits an animator makes on short sequences of motion to other sequences. Our method predicts frames for the motion using Gaussian process models of kinematics and dynamics. These estimates are combined with probabilistic inference. Our method can be used to propagate edits from examples to an entire sequence for an existing character, and it can also be used to map a motion from a control character to a very different target character. The technique shows good generalization. For example, we show that an estimator, learned from a few seconds of edited example animation using our methods, generalizes well enough to edit minutes of character animation in a high-quality fashion. Learning is interactive: An animator who wants to improve the output can provide small, correcting examples and the system will produce improved estimates of motion. We make this interactive learning process efficient and natural with a fast, full-body IK system with novel features. Finally, we present data from interviews with professional character animators that indicate that generalizing and propagating animator edits can save artists significant time and work.
GRAMPS
Authors: Sugerman Jeremy , Fatahalian Kayvon , Boulos Solomon , Akeley Kurt , Hanrahan Pat
Published: February 2009

We introduce GRAMPS, a programming model that generalizes concepts from modern real-time graphics pipelines by exposing a model of execution containing both fixed-function and application-programmable processing stages that exchange data via queues. GRAMPS allows the number, type, and connectivity of these processing stages to be defined by software, permitting arbitrary processing pipelines or even processing graphs. Applications achieve high performance using GRAMPS by expressing advanced rendering algorithms as custom pipelines, then using the pipeline as a rendering engine. We describe the design of GRAMPS, then evaluate it by implementing three pipelines, that is, Direct3D, a ray tracer, and a hybridization of the two, and running them on emulations of two different GRAMPS implementations: a traditional GPU-like architecture and a CPU-like multicore architecture. In our tests, our GRAMPS schedulers run our pipelines with 500 to 1500KB of queue usage at their peaks.
Fitting solid meshes to animated surfaces using linear elasticity
Authors: Choi Jaeil , Szymczak Andrzej
Published: February 2009

Computing correspondence between time frames of a time-dependent 3D surface is essential for the understanding of its motion and deformation. In particular, it can be a useful tool in compression, editing, texturing, or analysis of the physical or structural properties of deforming objects. However, correspondence information is not trivial to obtain for experimentally acquired 3D animations, such as time-dependent visual hulls (typically represented as either a binary occupancy grid or as a sequence of meshes of varying connectivity).

In this article we present a new nonrigid fitting method that can compute such correspondence information for objects that do not undergo large volume or topological changes, such as living creatures. Experimental results show that it is robust enough to handle visual hull data, allowing to convert it into a constant connectivity mesh with vertices moving in time. Our procedure first creates a rest-state mesh from one of the input frames. This rest-state mesh is then fitted to the consecutive frames. We do this by iteratively displacing its vertices so that a combination of surface distance and elastic potential energy is minimized. A novel rotation compensation method enables us to obtain high-quality results with linear elasticity, even in presence of significant bending.
Participating media illumination using light propagation maps
Authors: Fattal Raanan
Published: February 2009

Light traveling through semi-transparent media such as smoke and marble is absorbed and scattered. To achieve proper realistic visualizations of such media, illumination algorithms must account for these events. In this article, we present a new method for solving the
Radiative Transport Equation
, which models such evolution of light. The new method falls into the category of the
Discrete Ordinates Method
and inherits its generality and computational lightness. This method is known to suffer from two main shortcomings, namely
false scattering
and the
ray effect
, which we avoid in our new method. By propagating the light using low-dimensional maps of rays we detach their transport from the Eulerian grid and use fine angular discretizations. Thus, the scattering effect at each scattering generation is eliminated and the ray effect is significantly reduced at no additional memory requirements. Results demonstrate the new method's efficiency, ability to produce high-quality approximations, and its usefulness for a wide range of computer graphics applications.
Data-driven curvature for real-time line drawing of dynamic scenes
Authors: Kalogerakis Evangelos , Nowrouzezahrai Derek , Simari Patricio , Mccrae James , Hertzmann Aaron , Singh Karan
Published: February 2009

This article presents a method for real-time line drawing of deforming objects. Object-space line drawing algorithms for many types of curves, including suggestive contours, highlights, ridges, and valleys, rely on surface curvature and curvature derivatives. Unfortunately, these curvatures and their derivatives cannot be computed in real-time for animated, deforming objects. In a preprocessing step, our method learns the mapping from a low-dimensional set of animation parameters (e.g., joint angles) to surface curvatures for a deforming 3D mesh. The learned model can then accurately and efficiently predict curvatures and their derivatives, enabling real-time object-space rendering of suggestive contours and other such curves. This represents an order-of-magnitude speedup over the fastest existing algorithm capable of estimating curvatures and their derivatives accurately enough for many different types of line drawings. The learned model can generalize to novel animation sequences and is also very compact, typically requiring a few megabytes of storage at runtime. We demonstrate our method for various types of animated objects, including skeleton-based characters, cloth simulation, and blend-shape facial animation, using a variety of nonphotorealistic rendering styles.

An important component of our system is the use of dimensionality reduction for differential mesh data. We show that Independent Component Analysis (ICA) yields localized basis functions, and gives superior generalization performance to that of Principal Component Analysis (PCA).
Multivariate Generalization of the Confluent Hypergeometric Function Kind 1 Distribution
Authors: Nagar Daya K. , Sepúlveda-Murillo Fabio Humberto
Published: February 2009

The confluent hypergeometric function kind 1 distribution with the probability density
function (pdf) proportional to occurs as the distribution of the ratio of independent gamma and beta variables. In this article, a multivariate generalization
of this distribution is defined and derived. Several pertinent properties of this multivariate
distribution are discussed that shed some light on the nature of the distribution.
A Hull and White Formula for a General Stochastic Volatility Jump‐Diffusion Model with Applications to the Study of the Short‐Time Behavior of the Implied Volatility
Authors: Alòs Elisa , León Jorge A. , Pontier Monique , Vives Josep
Published: February 2009

We obtain a Hull and White type formula for a
general jump‐diffusion stochastic volatility model, where the
involved stochastic volatility process is correlated not only with
the Brownian motion driving the asset price but also with the
asset price jumps.
Towards this end, we establish an anticipative Itô′s formula, using Malliavin calculus techniques for Lévy processes on the canonical space. As an application, we show that the dependence of the volatility process on the asset price jumps has no effect on the short‐time behavior of the
at‐the‐money implied volatility skew.
Strong Convergence of a Modified Halpern's Iteration for Nonexpansive Mappings
Authors: Hu Liang-Gen
Published: February 2009

The purpose of this paper is to consider that a modified Halpern's iterative sequence "Equation missing" converges strongly to a fixed point of nonexpansive mappings in Banach spaces which have a uniformly Gâteaux differentiable norm. Our result is an extension of the corresponding results.
Antibiotic Resistance Patterns in Invasive Group B Streptococcal Isolates
Authors: Castor Mei L. , Whitney Cynthia G. , Como-Sabetti Kathryn , Facklam Richard R. , Ferrieri Patricia , Bartkus Joanne M. , Juni Billie A. , Cieslak Paul R. , Farley Monica M. , Dumas Nellie B. , Schrag Stephanie J. , Lynfield Ruth
Published: February 2009

Antibiotics are used for both group B streptococcal (GBS) prevention and treatment. Active population-based surveillance for invasive GBS disease was conducted in four states during 1996—2003. Of 3813 case-isolates, 91.0% (3471) were serotyped, 77.1% (2937) had susceptibility testing, and 46.6% (3471) had both. All were sensitive to penicillin, ampicillin, cefazolin, cefotaxime, and vancomycin. Clindamycin and erythromycin resistance was 12.7% and 25.6%, respectively, and associated with serotype V (P<.001). Clindamycin resistance increased from 10.5% to 15.0% (X2for trend 12.70;P<.001); inducible clindamycin resistance was associated with theermgenotype. Erythromycin resistance increased from 15.8% to 32.8% (X2for trend 55.46;P<.001). While GBS remains susceptible to beta-lactams, resistance to alternative agents such as erythromycin and clindamycin is an increasing concern.
Coelomocytes: Biology and Possible Immune Functions in Invertebrates with Special Remarks on Nematodes
Authors: Tahseen Qudsia
Published: February 2009

All metazoans are exposed to a wide range of microbes and have evolved complex immune defenses used to repel infectious agents. Coelomocytes play a key role in the defense reactions of most invertebrates. They are involved in important immune functions, such as phagocytosis, encapsulation, graft rejection, and inflammation, as well as the synthesis and secretion of several humoral factors especially in annelids and echinoderms. Coelomocytes in nematodes are variable in shapes from round, ovoid, cuboidal, and spindle-shaped to stellate or branched cells that are found usually at fixed positions in the pseudocoelom. Their number usually varies from 2 to 6. The model nematode,C. eleganslacks an adaptive immune system and the coelomocytes are capable of endocytosis, but their involvement in phagocytosis of bacteria seems unlikely. The aim of this review is to evaluate current knowledge on coelomocytes of invertebrates with special reference to nematodes. The morphology and structure of these coelomocytes are discussed along with their origin. Their relative positions and diversity in different nematode groups have also been discussed and illustrated.
Human Hematopoietic Stem Cells Can Survive In Vitro for Several Months
Authors: Ishigaki Taro , Sudo Kazuhiro , Hiroyama Takashi , Miharada Kenichi , Ninomiya Haruhiko , Chiba Shigeru , Nagasawa Toshiro , Nakamura Yukio
Published: February 2009

We previously reported that long-lasting in vitro hematopoiesis could be achieved using the cells differentiated from primate embryonic stem (ES) cells. Thus, we speculated that hematopoietic stem cells differentiated from ES cells could sustain long-lasting in vitro hematopoiesis. To test this hypothesis, we investigated whether human hematopoietic stem cells could similarly sustain long-lasting in vitro hematopoiesis in the same culture system. Although the results varied between experiments, presumably due to differences in the quality of each hematopoietic stem cell sample, long-lasting in vitro hematopoiesis was observed to last up to nine months. Furthermore, an in vivo analysis in which cultured cells were transplanted into immunodeficient mice indicated that even after several months of culture, hematopoietic stem cells were still present in the cultured cells. To the best of our knowledge, this is the first report to show that human hematopoietic stem cells can survive in vitro for several months.
Particle Size and Pore Structure Characterization of Silver Nanoparticles Prepared by Confined Arc Plasma
Authors: Zhou Mingru , Wei Zhiqiang , Qiao Hongxia , Zhu Lin , Yang Hua , Xia Tiandong
Published: February 2009

In the protecting inert gas, silver nanoparticles were successfully prepared by confined arc plasma method. The particle size, microstructure, and morphology of the particles by this process were characterized via X‐ray powder diffraction (XRD), transmission electron microscopy (TEM) and the corresponding selected area electron diffraction (SAED). The N2 absorption‐desorption isotherms of the samples were measured by using the static volumetric absorption analyzer, the pore structure of the sample was calculated by Barrett‐Joyner‐Halenda (BJH) academic model, and the specific surface area was calculated from Brunauer‐Emmett‐Teller (BET) adsorption equation. The experiment results indicate that the crystal structure of the samples is face‐centered cubic (FCC) structure the same as the bulk materials, the particle size distribution ranging from 5 to 65 nm, with an average particle size about 26 nm obtained by TEM and confirmed by XRD and BET results. The specific surface area is 23.81 m2/g, pore volumes are 0.09 cm3/g, and average pore diameter is 18.7 nm.
Interaction between Tobacco and Alcohol Use and the Risk of Head and Neck Cancer: Pooled Analysis in the International Head and Neck Cancer Epidemiology Consortium
Authors: Hashibe Mia , Brennan Paul , Chuang Shu-chun , Boccia Stefania , Castellsague Xavier , Chen Chu , Curado Maria Paula , Dal Maso Luigino , Daudt Alexander W. , Fabianova Eleonora , Fernandez Leticia , Wünsch-Filho Victor , Franceschi Silvia , Hayes Richard B. , Herrero Rolando , Kelsey Karl , Koifman Sergio , La Vecchia Carlo , Lazarus Philip , Levi Fabio , Lence Juan J. , Mates Dana , Matos Elena , Menezes Ana , McClean Michael D. , Muscat Joshua , Eluf-Neto Jose , Olshan Andrew F. , Purdue Mark , Rudnai Peter , Schwartz Stephen M. , Smith Elaine , Sturgis Erich M. , Szeszenia-Dabrowska Neonilia , Talamini Renato , Wei Qingyi , Winn Deborah M. , Shangina Oxana , Pilarska Agnieszka , Zhang Zuo-Feng , Ferro Gilles , Berthiller Julien , Boffetta Paolo
Published: February 2009

Background: The magnitude of risk conferred by the interaction between tobacco and alcohol use on the risk of head and neck cancers is not clear because studies have used various methods to quantify the excess head and neck cancer burden.

Methods: We analyzed individual-level pooled data from 17 European and American case-control studies (11,221 cases and 16,168 controls) participating in the International Head and Neck Cancer Epidemiology consortium. We estimated the multiplicative interaction parameter (ψ) and population attributable risks (PAR).

Results: A greater than multiplicative joint effect between ever tobacco and alcohol use was observed for head and neck cancer risk (ψ = 2.15; 95% confidence interval, 1.53-3.04). The PAR for tobacco or alcohol was 72% (95% confidence interval, 61-79%) for head and neck cancer, of which 4% was due to alcohol alone, 33% was due to tobacco alone, and 35% was due to tobacco and alcohol combined. The total PAR differed by subsite (64% for oral cavity cancer, 72% for pharyngeal cancer, 89% for laryngeal cancer), by sex (74% for men, 57% for women), by age (33% for cases <45 years, 73% for cases >60 years), and by region (84% in Europe, 51% in North America, 83% in Latin America).

Conclusions: Our results confirm that the joint effect between tobacco and alcohol use is greater than multiplicative on head and neck cancer risk. However, a substantial proportion of head and neck cancers cannot be attributed to tobacco or alcohol use, particularly for oral cavity cancer and for head and neck cancer among women and among young-onset cases. (Cancer Epidemiol Biomarkers Prev 2009;18(2):541–50)
Disparities in How Parents Are Learning about the Human Papillomavirus Vaccine
Authors: Hughes Jessica , Cates Joan R. , Liddon Nicole , Smith Jennifer S. , Gottlieb Sami L. , Brewer Noel T.
Published: February 2009

Background: Differential access to basic health information may contribute to persistent cervical cancer disparities. We examined whether human papillomavirus (HPV) vaccine awareness, HPV knowledge, and use of information sources about the vaccine differ by sociodemographic characteristics associated with cervical cancer.

Methods: Study participants (n = 889) were caregivers of adolescent girls ages 10 to 18 years living in southeastern North Carolina. Analyses simultaneously controlled for caregivers' gender, race, age, education, income, and rural residence.

Results: Although most caregivers were aware of HPV (83%) and the HPV vaccine (82%), awareness differed by gender, race, education, and income. The largest differences were for race, with 87% of Whites versus 68% of African Americans having heard of the vaccine (P < 0.001). Caregivers correctly answered an average of 69% of questions on HPV, with differences by race and education. Most respondents heard of the HPV vaccine through drug company advertisements (83%) or broadcast media coverage (69%). African Americans were less likely than Whites to have heard about the vaccine from advertisements but more likely from a broadcast source (P < 0.05). Health care providers (88%) and the internet (65%) were the most favored sources for future information about the vaccine. Vaccine uptake was associated with awareness, knowledge, and media use.

Discussion: Whereas drug company advertisements seem to play a central role in high HPV vaccine awareness, doctors and the internet are the preferred future “go to” sources for seeking out information. Communication-based interventions for caregivers from cervical cancer risk groups, especially African Americans, may need to use different communication channels and content. (Cancer Epidemiol Biomarkers Prev 2009;18(2):363–72)
Reproductive and Hormonal Factors, and Ovarian Cancer Risk for BRCA1 and BRCA2 Mutation Carriers: Results from the International BRCA1/2 Carrier Cohort Study
Authors: Antoniou Antonis C. , Rookus Matti , Andrieu Nadine , Brohet Richard , Chang-Claude Jenny , Peock Susan , Cook Margaret , Evans D. Gareth , Eeles Rosalind ,   EMBRACE, Nogues Catherine , Faivre Laurence , Gesta Paul ,   GENEPSO, van Leeuwen Flora E. , Ausems Margreet G.E.M. , Osorio Ana ,   GEO-HEBON, Caldes Trinidad , Simard Jacques , Lubinski Jan , Gerdes Anne-Marie , Olah Edith , Fürhauser Christine , Olsson Hakan , Arver Brita , Radice Paolo , Easton Douglas F. , Goldgar David E.
Published: February 2009

Background: Several reproductive and hormonal factors are known to be associated with ovarian cancer risk in the general population, including parity and oral contraceptive (OC) use. However, their effect on ovarian cancer risk for BRCA1 and BRCA2 mutation carriers has only been investigated in a small number of studies.

Methods: We used data on 2,281 BRCA1 carriers and 1,038 BRCA2 carriers from the International BRCA1/2 Carrier Cohort Study to evaluate the effect of reproductive and hormonal factors on ovarian cancer risk for mutation carriers. Data were analyzed within a weighted Cox proportional hazards framework.

Results: There were no significant differences in the risk of ovarian cancer between parous and nulliparous carriers. For parous BRCA1 mutation carriers, the risk of ovarian cancer was reduced with each additional full-term pregnancy (P trend = 0.002). BRCA1 carriers who had ever used OC were at a significantly reduced risk of developing ovarian cancer (hazard ratio, 0.52; 95% confidence intervals, 0.37-0.73; P = 0.0002) and increasing duration of OC use was associated with a reduced ovarian cancer risk (P trend = 0.0004). The protective effect of OC use for BRCA1 mutation carriers seemed to be greater among more recent users. Tubal ligation was associated with a reduced risk of ovarian cancer for BRCA1 carriers (hazard ratio, 0.42; 95% confidence intervals, 0.22-0.80; P = 0.008). The number of ovarian cancer cases in BRCA2 mutation carriers was too small to draw definitive conclusions.

Conclusions: The results provide further confirmation that OC use, number of full-term pregnancies, and tubal ligation are associated with ovarian cancer risk in BRCA1 carriers to a similar relative extent as in the general population. (Cancer Epidemiol Biomarkers Prev 2009;18(2):601–10)
Decreased Expression of Inhibitor of Growth 4 Correlated with Poor Prognosis of Hepatocellular Carcinoma
Authors: Fang Feng , Luo Lai-Bang , Tao Yi-Ming , Wu Fan , Yang Lian-Yue
Published: February 2009

Objective: Inhibitor of growth 4 (ING4) is a candidate tumor suppressor that plays an important role in tumor growth and angiogenesis. Here, we examined the expression of ING4 in hepatocellular carcinoma (HCC) tissues and analyzed its correlation with the progression of HCC.

Methods: Specimens from 136 HCC patients were determined immunohistochemically for ING4 expression. The correlation of ING4 levels with clinicopathologic variables, prognosis, and metastatic potential was analyzed. Among the 136 cases, 36 paired HCC and paracarcinomatous liver tissue specimens were analyzed for ING4 expression levels by real-time quantitative reverse transcription-PCR and Western blotting. MVD was determined by CD34 immunostaining to test whether it correlated with ING4 protein expression level.

Results: The ING4 mRNA and protein levels were significantly lower in HCC than paracarcinomatous liver tissue from both real-time quantitative reverse transcription-PCR and Western blotting (P = 0.039 and 0.012, respectively). Importantly, the ING4 protein level correlated with the Edmondson-Steiner grade (P = 0.035), vein invasion (P = 0.015), and microvessel density (P = 0.005). Survival and metastasis analysis indicated that HCC patients with lower ING4 expression had poorer overall survival and disease-free survival than those with high expression (P = 0.0001 and 0.0065; respectively). Multivariable Cox regression analysis revealed that the ING4 expression level was an independent factor for prognosis (hazard risk, 9.63; P = 0.001).

Conclusions: ING4 expression is down-regulated in HCC tissues. ING4 expression level correlates with prognosis and metastatic potential, which suggests that ING4 is a candidate prognostic marker of HCC. (Cancer Epidemiol Biomarkers Prev 2009;18(2):409–16)
Social-Cognitive and School Factors in Initiation of Smoking among Adolescents: A Prospective Cohort Study
Authors: Bidstrup Pernille Envold , Frederiksen Kirsten , Siersma Volkert , Mortensen Erik Lykke , Ross Lone , Vinther-Larsen Mathilde , Grønbæk Morten , Johansen Christoffer
Published: February 2009

Aims: The aim of the present study was to examine the association between social-cognitive factors, school factors, and smoking initiation among adolescents who had never smoked.

Methods: The study was based on longitudinal data on Danish adolescents attending randomly selected public schools. Adolescents enrolled in grade 7 (mean age, 13 years) who had never smoked (n = 912) were followed up for 6 months after baseline. Those who had still never smoked were followed up again 18 months after baseline, in grade 8 (n = 442). Social-cognitive factors were examined with five measures: self-efficacy, social influence (norms), social influence (behavior), social influence (pressure), and attitude. We used multilevel analyses to estimate the associations between social-cognitive factors at baseline and smoking initiation as well as the random effects of school, school class, and gender group in the school class.

Results: At the first follow-up, we found significant associations between attitude, father's smoking, best friend's smoking, and smoking initiation. At the second follow-up, we found a significant association with pressure to smoke from friends. Of the school factors, gender group in the school class showed an effect at both first and second follow-up.

Conclusion: Our results suggest that father's smoking, best friend's smoking, attitude, and pressure to smoke from friends affect smoking initiation. The results for school factors suggest an effect of classmates of the same gender, which has not previously been examined longitudinally. (Cancer Epidemiol Biomarkers Prev 2009;18(2):384–92)
Sperm-Associated Antigen 9, a Novel Biomarker for Early Detection of Breast Cancer
Authors: Kanojia Deepika , Garg Manoj , Gupta Samir , Gupta Anju , Suri Anil
Published: February 2009

To date, there have been no tumor biomarkers validated and incorporated into oncologic practice for the early diagnosis of breast cancer. Recently, we showed that sperm-associated antigen 9 (SPAG9), a member of cancer testis (CT) antigen family, is associated with ovarian carcinomas. In the present study, we investigated SPAG9 expression and humoral immune response in breast cancer. We further evaluated the diagnostic potential of autoantibodies to SPAG9 protein in various stages, grades, and histotypes of breast cancer. We analyzed the association of SPAG9 immunoreactivity score (IRS) with predicted risk of breast cancer recurrence over 10 years. Our reverse transcription-PCR and immunohistochemical analyses revealed SPAG9 expression in 88% breast cancer specimens independent of tumor stages and grades. Further, the humoral immune response against SPAG9 was detected in 80% breast cancer patients with SPAG9-expressing tumors. The linear regression modeling predicted a direct relationship between presence of lymphovascular invasion and high SPAG9 IRS, whereas the univariate and multivariate logistic regression models predicted a strong association of SPAG9 IRS with tumor grade. Further, our data indicated a significant higher trend of SPAG9 IRS with the predicted high risk of breast cancer recurrence. The present investigation reports for the first time SPAG9 expression and humoral immune response in early stages and low-grade breast cancer. Although our data indicated that autoantibodies against SPAG9 represent a promising approach for the development of biomarker, further large-scale validation studies are required to establish its potential use in early diagnosis and monitoring of breast cancer recurrence. (Cancer Epidemiol Biomarkers Prev 2009;18(2):630–9)