bluuebunny/crossref_metadata_2025 huggingface dataset:
Evolution of surveillance methods for detection of bacterial contamination of platelets in a university hospital, 1991 through 2004
Authors: Yomtovian Roslyn A. , Palavecino Elizabeth L. , Dysktra Alden H. , Downes Katharine A. , Morrissey Anne M. , Bajaksouzian Saralee , Pokorny Marcella A. , Lazarus Hillard M. , Jacobs Michael R.
Published: May 2006

BACKGROUND:  Platelet (PLT) bacterial contamination (PBC) is the most common transfusion‐associated infection. It is important to understand the impact of interventions addressing this problem.

STUDY DESIGN AND METHODS:  PBC was studied by prospective (active) and transfusion‐reaction triggered (passive) surveillance from July 1991 to December 2004. Active surveillance, utilized for 10 years, included bacterial culture of all or 4‐ and 5‐day‐old PLTs at issue and intermittent use of Gram stain, pH measurements, and early (24‐hr) culture of single‐donor plateletpheresis (SDP) units.

RESULTS:  Active surveillance detected 38 instances of PBC, 7 in SDP units (1:2213) and 31 in random‐donor PLT units (1:2090 units, p = 0.89; or 1:418 pools of 5 units, p < 0.001). Contaminants were coagulase‐negative staphylococci (CONS; n = 27), Staphylococcus aureus (4), Bacillus cereus (1), Serratia marcescens (2), streptococci (2 S. bovis, 1 S. uberis), and CONS with viridans group streptococcus (1). Only one instance of contamination, caused by Pseudomonas aeruginosa, was detected by passive surveillance, with fatal outcome. Colony counts of contaminants ranged from 0.5 × 102 to 4 × 1011 colony‐forming units per mL at time of issue. PBC was interdicted before transfusion in 6 cases through Gram stain screening. Transfusion reactions occurred in 13 of 32 recipients (41%), with 9 severe reactions (28%) and 3 deaths (9%). pH testing failed to detect 5 contaminated units and resulted in discard of nearly 2 percent of units, whereas culture of SDP units at 24 hours failed to identify a contaminated unit.

CONCLUSION:  Improved active surveillance methods for detecting PBC are needed to improve the safety of PLT transfusions.
Suppression of Autonomic‐Mediated Triggered Firing in Pulmonary Vein Preparations, 24 Hours Postcoronary Artery Ligation in Dogs
Authors: PATTERSON EUGENE , YU XICHUN , HUANG SHIJUN , GARRETT MARION , KEM DAVID C.
Published: May 2006

Introduction: Rapid arrhythmia originating within pulmonary veins (PVs) precipitates atrial fibrillation (AF) in man. To determine a possible basis for an increased incidence of AF observed peri‐myocardial infarction in man, we compared AF induction in vivo and triggered arrhythmia formation within isolated PVs in vitro in normal dogs and dogs studied 24 hours postcoronary artery ligation.

Methods and Results: The incidence of AF initiated by atrial premature stimuli was increased in dogs postcoronary artery ligation (6/9) versus normal (2/12) (P = 0.03). In isolated PVs from normal hearts, pause‐dependent early afterdepolarizations (EADs) were enhanced by catecholamines. Rapid arrhythmia (1,182 ± 213 beats/min) was triggered during isoproterenol/norepinephrine (32 nM) + acetylcholine (100 nM) (N = 16/23) using the same pacing pauses eliciting EADs. Rapid arrhythmia (802 ± 161 beats/min) was also triggered by local autonomic nerve stimulation (ANS; N = 18/23). Despite equivalent pause‐dependent afterdepolarization formation in PVs from infarcted hearts, a rightward 45‐fold and 28‐fold shift in the dose–response curve for afterdepolarization enhancement was observed for isoproterenol and norepinephrine, respectively (P < 0.02). ANS (N = 1/19) and isoproterenol/norepinephrine (32 nM) + acetylcholine (100 nM) (N = 0/9 and 0/12, respectively) (P = 0.0001) failed to elicit arrhythmia formation. Beta‐adrenergic receptor desensitization was associated with a 2.5‐fold increase in PV beta‐adrenergic receptor kinase (ARK).

Conclusion: The data demonstrate decreased susceptibility of isolated canine PVs for arrhythmia triggered by local ANS, or pacing pauses in the presence of a catecholamine + acetylcholine, postmyocardial infarction, despite a greater susceptibility of the intact heart to AF. The decreased arrhythmia susceptibility was observed coincident with an increase in beta‐ARK and a decreased responsiveness to beta‐adrenergic receptor agonists.
Semiparametric Analysis of Zero‐Inflated Count Data
Authors: Lam K. F. , Xue Hongqi , Bun Cheung Yin
Published: May 2006

SummaryMedical and public health research often involve the analysis of count data that exhibit a substantially large proportion of zeros, such as the number of heart attacks and the number of days of missed primary activities in a given period. A zero‐inflated Poisson regression model, which hypothesizes a two‐point heterogeneity in the population characterized by a binary random effect, is generally used to model such data. Subjects are broadly categorized into the low‐risk group leading to structural zero counts and high‐risk (or normal) group so that the counts can be modeled by a Poisson regression model. The main aim is to identify the explanatory variables that have significant effects on (i) the probability that the subject is from the low‐risk group by means of a logistic regression formulation; and (ii) the magnitude of the counts, given that the subject is from the high‐risk group by means of a Poisson regression where the effects of the covariates are assumed to be linearly related to the natural logarithm of the mean of the counts. In this article we consider a semiparametric zero‐inflated Poisson regression model that postulates a possibly nonlinear relationship between the natural logarithm of the mean of the counts and a particular covariate. A sieve maximum likelihood estimation method is proposed. Asymptotic properties of the proposed sieve maximum likelihood estimators are discussed. Under some mild conditions, the estimators are shown to be asymptotically efficient and normally distributed. Simulation studies were carried out to investigate the performance of the proposed method. For illustration purpose, the method is applied to a data set from a public health survey conducted in Indonesia where the variable of interest is the number of days of missed primary activities due to illness in a 4‐week period.
Altered expression of goblet cell‐ and mucin glycosylation‐related genes in the intestinal epithelium during infection with the nematode Nippostrongylus brasiliensis in rat
Authors: YAMAUCHI JUNKO , KAWAI YUICHI , YAMADA MINORU , UCHIKAWA RYUICHI , TEGOSHI TATSUYA , ARIZONO NAOKI
Published: May 2006

Intestinal nematode infection induces marked goblet cell hyperplasia and mucus secretion, but the mechanisms of regulation of the changes still remain to be elucidated. In the present study, epithelial cells were isolated from the rat small intestine at various times after Nippostrongylus brasiliensis infection, and the levels of expression of goblet cell‐ and mucin glycosylation‐related genes were estimated by semi‐quantitative reverse transcription (RT)‐PCR. Among the genes investigated, mucin core peptide (MUC) 2, sialyltransferase (Siat) 4c and trefoil factor family (TFF) 3 were upregulated as early as 2–4 days post‐infection, suggesting that they are associated with an early innate protective response. Seven days post‐infection and thereafter, when the nematodes reached maturity, significant upregulation of MUC3, MUC4, resistin‐like molecule β (Relmβ) and 3O‐sulfotransferase (3ST)1 was observed, while 3ST2 expression levels increased after the majority of the worms were expelled from the intestine. Similar alterations of glycosylation‐related gene expression were also observed in mast‐cell‐deficient Ws/Ws rats, suggesting that mast cells in the epithelium are not relevant to the upregulation of these genes. The present finding that the expression level of each goblet cell‐ or glycosylation‐related gene was altered differently during the time course of infection indicates the progression of sequential qualitative changes in the mucus layer after infection.
Interspecies variation in Candida biofilm formation studied using the Calgary biofilm device
Authors: PARAHITIYAWA N. B. , SAMARANAYAKE Y. H. , SAMARANAYAKE L. P. , YE J. , TSANG P. W. K. , CHEUNG B. P. K. , YAU J. Y. Y. , YEUNG S. K. W.
Published: May 2006

An in vitro assay to study multiple Candida biofilms, in parallel, has been carried out using the Calgary biofilm device (CBD). We here report: i) standardization of the CBD for Candida albicans biofilm formation, ii) kinetics of C. albicans biofilm formation, iii) biofilm formation by five Candida species, and iv) effect of dietary carbohydrates on biofilm formation. The biofilm metabolic activity on all CBD pegs was similar (p=0.6693) and C. albicans biofilm formation revealed slow growth up to 36 h and significantly higher growth up to 48 h (p<0.001). Significant differences in total biofilm metabolic activity were seen for glucose, fructose and lactose grown C. albicans compared with sucrose and maltose grown yeasts. Candida krusei developed the largest biofilm mass (p<0.05) relative to C. albicans, C. glabrata, C. dubliniensis and C. tropicalis. Scanning electron microscopy revealed that C. krusei produced a thick multilayered biofilm of pseudohyphal forms embedded within the polymer matrix, whereas C. albicans, C. dubliniensis and C. tropicalis biofilms consisted of clusters or chains of cells with sparse extracellular matrix material. We conclude that CBD is a useful, simple, low cost miniature device for parallel study of Candida biofilms and factors modulating this phenomenon.
Comparison of efficacy of moxidectin and ivermectin in the treatment of Strongyloides fulleborni infection in rhesus macaques
Authors: Dufour Jason P. , Cogswell Frank B. , Phillippi‐Falkenstein Kathrine M. , Bohm Rudolf P.
Published: May 2006

Background  Strongyloides infection may result in clinical disease or confound experimental protocols that utilize non‐human primates. There is presently a Strongyloides fulleborni infection rate of approximately 27% in the Tulane National Primate Research Center's breeding colonies despite the routine therapeutic and prophylactic use of ivermectin.

Methods  A study was conducted to determine if moxidectin treatment offers advantages to the intestinal parasite control program. A total of 150 rhesus macaques (Macaca mulatta) that were removed from the breeding colonies due to illness were selected for the study. The animals were randomly assigned to treatment groups with 75 receiving ivermectin and 75 receiving moxidectin. Egg counts were performed on fecal samples collected pre‐ and post‐treatment.

Results  Both treatments resulted in decreases in the number of eggs/g in the post‐treatment sample as compared with the pre‐treatment sample; however, no significant difference was found between treatment groups.

Conclusions  With the data demonstrating a similar efficacy in both ivermectin and moxidectin treated macaques, the benefit of moxidectin treatment relates to biosafety and topical application.
Amelogenin, a major structural protein in mineralizing enamel, is also expressed in soft tissues: brain and cells of the hematopoietic system
Authors: Deutsch Dan , Haze‐Filderman Amir , Blumenfeld Anat , Dafni Leah , Leiser Yoav , Shay Boaz , Gruenbaum‐Cohen Yael , Rosenfeld Eli , Fermon Eran , Zimmermann Bernard , Haegewald Stefan , Bernimoulin Jean‐Pierre , Taylor Angela L.
Published: May 2006

The amelogenin protein is considered as the major molecular marker of developing and mineralizing ectodermal enamel. It regulates the shape, size, and direction of growth of the enamel mineral crystallite. Recent data suggest other roles for amelogenin beyond regulation of enamel mineral crystal growth. The present study describes our recent discovery of amelogenin expression in soft tissues: in brain and in cells of the hematopoietic system, such as macrophages, megakaryocytes and in some of the hematopoietic stem cells. Reverse transcription–polymerase chain reaction (RT–PCR) followed by cDNA sequencing revealed, in mouse brain, two amelogenin mRNA isoforms: the full‐length amelogenin including exon 4, and the isoform lacking exon 4. Immunohistochemistry revealed amelogenin expression in brain glial cells. Mouse macrophages were found to express the full‐length amelogenin sequence lacking exon 4. Confocal microscopy revealed colocalization of amelogenin and CD41 (a megakaryocyte marker), as well as amelogenin and CD34 (a hematopoietic stem cell marker) in some of the bone marrow cells. The expression of amelogenin, a major structural protein of the mineralizing extracellular enamel matrix, also in cells of non‐mineralizing soft tissues, suggests that amelogenin is multifunctional. Several different potential functions of amelogenin are discussed.
Growth of ameloblast‐lineage cells in a three‐dimensional Matrigel environment
Authors: Li Wu , Machule Darren , Gao Cen , DenBesten Pamela K.
Published: May 2006

Enamel organ epithelial cells grow in culture as two distinct cell populations – either stellate‐shaped or polygonal‐shaped cells. The polygonal cells have an ameloblast cell phenotype and are difficult to grow in culture beyond two passages. This study was designed to determine the effects of a Matrigel three‐dimensional (3D) environment on polygonal cells, as compared with stellate cells, derived from porcine tooth enamel organ. Enamel organs were dissected free from the unerupted molars of 30‐kg pigs and then grown in LCH‐8e media, either with or without serum. Cells grown in serum‐free media were primarily polygonal shaped, whereas cells grown in media containing serum were stellate shaped. Both types of cells were grown in a 3D Matrigel matrix. In addition, polygonal‐shaped cells were mixed with hydroxyapatite powder and transplanted subcutaneously into nude mice. Polygonal‐shaped epithelial cells formed cell groups, similar to epithelial pearls, both in vitro and in vivo. The stellate‐shaped cells, in contrast, did not form similar structures, but remained suspended in the Matrigel and gradually disappeared from the culture. These results suggest that a Matrigel environment, rich in basement membrane and matrix proteins, selects for polygonal‐shaped ameloblast‐lineage cells and induces the formation of epithelial pearls.
Towards second‐generation proteome analysis of murine enamel‐forming cells
Authors: Mangum Jonathan E. , Veith Paul D. , Reynolds Eric C. , Hubbard Michael J.
Published: May 2006

Proteome analysis of rat enamel‐forming cells, initiated over a decade ago, has provided valuable insights to enamel biology. In preparation for a more comprehensive, second‐generation proteomic exploration, we evaluated an updated microsample‐profiling strategy that comprises sequential extraction of enamel epithelium, parallel one‐ and two‐dimensional gel electrophoresis, and mass spectrometric sequence analysis. The results indicated that several hundred proteins, representing various cellular compartments (including membranes), are amenable to identification with a starting tissue volume of < 10 µl. With its increased proteomic depth and breadth, this straightforward approach constitutes a major advance from the first‐generation work (10‐fold increased proteome coverage), although care was needed to ensure a comparably high stringency of protein identification. Expression proteomics has an exciting potential to elucidate the inner workings of murine enamel epithelial cells, leading to an improved understanding of enamel in health and disease.
Control of apatite crystal growth by the co‐operative effect of a recombinant porcine amelogenin and fluoride
Authors: Iijima Mayumi , Du Chang , Abbott Christopher , Doi Yutaka , Moradian‐Oldak Janet
Published: May 2006

Recently, we used native amelogenins extracted from developing pig enamel to examine the combined effect of fluoride and amelogenins on the growth of octacalcium phosphate (OCP) and apatite crystals. The purpose of the present study was to investigate this combined effect using a highly purified recombinant amelogenin. We applied porcine amelogenin (rP172) and fluoride in a dual‐membrane system as a model for tooth enamel formation. The combination of rP172 and fluoride in this system resulted in the formation of rod‐like apatite crystals. On the other hand, without fluoride, rod‐like OCP crystals of a comparable size were formed, and rather large hexagonal prisms of mixed crystals of OCP and apatite grew without amelogenins. Thus, highly purified and homogeneous recombinant amelogenin, in co‐operation with F, regulated the mineral phase, habit, and size of crystals in the same manner as the extracted heterogeneous porcine amelogenins. We suggest that in both cases the control over the crystal phase and morphology was a direct effect of amelogenin protein serving as a scaffold for apatite mineralization.
1140919448 CD200‐dependent suppression of human NK activity by IVIG requires CD200 receptor type 2
Authors: Clark DA , Banwatt D , Gorczynski R , Blajchman MA
Published: May 2006

Problem:  IVIG prepared from plasma of stored human blood can be efficacious in improving pregnancy success in a selected subgroup of patients but RCTs using an IVIG showing inferior suppression of NK activity in vitro have been negative (J Assist Reprod Genet 2006). A significant component of NK suppression by IVIG appears to be due to CD200 released into plasma from PBL during storage at 4C. CD200 receptors (CD200R) are expressed at the fetomaternal interface prior to onset of abortion; CD200R1 mediates direct effects on gamma‐delta T cell development and suppresses alpha‐beta T cell responses in vitro, whereas CD200R2 alters DC so as to facilitate development of alpha‐beta Treg cells. Which receptor(s) mediate NK cell suppression?

Methods:  Purified human PBL or the CD56+ NK cell subset of PBL were used to lyse 51Cr‐labeled K562 cells in vitro. Different IVIG preparations were tested for suppressive ability, and suppression was blocked by either anti‐huCD200 mAb or rabbit anti‐huCD200R1 or R2 antibodies.

Results:  CD200‐dependent IVIG NK suppressive potency differed among IVIG types (Gammagard>Gamunex>>Gamimmune). CD200‐dependent suppression was blocked by anti‐CD200R antibody able to react with the type 2 receptor. K562 cells did not express receptor, and purified CD56+ NK cells were suppressed effectively without the need for non‐NK cells.

Conclusions:  IVIG may directly express NK cell activity via CD200 binding to CD200R2.
Arterial complications of thoracic outlet syndrome
Authors: Singh Devender , Pinjala Rama Krishna , Reddy Lankala Rama Chander , Vani Venkat NagLaxmi
Published: May 2006

Objective: Arterial vascular complications resulting from thoracic outlet compression, although rare, can be substantial and potentially limb threatening. These complications are due to compressions at the thoracic outlet, the treatment of which continues to be a dilemma. The objective of the present study was to review our experience with this problem with particular reference to its management.

Methods: We performed a retrospective study of 12 years and retrieved data from the medical records department of Nizam’s Institute of Medical Sciences, Hyderabad, India. A retrospective review identified 35 patients (age range 15–50 years). In 31 patients, the vasculopathy was caused by a cervical rib, soft tissue anomalies (n = 31), and an elongated transverse process (n = 4). Evaluation included assessment with colour duplex and arteriography with positional maneuvers. Thirty‐two patients presented with a fixed pulse deficit, 22 patients had palpable mass and 15 patients had distal embolization.

Results: In 31 patients with cervical rib, the rib was excised via a supraclavicular approach, Scalenectomy was performed and the arterial pathology was repaired on its merit, usually by a vein graft replacement or bypass. The elongated process was excised in the other four patients. Twelve patients required thrombectomy of the distal arteries and a bypass procedure (with a vein/prosthetic graft) was performed in 14 patients. Dorsal sympathectomy, as an adjunct, was carried out in 10 patients. In view of their advanced distal disease, four patients were given prostaglandin therapy. Short‐term follow up of 2 years showed good results.

Conclusion: Our results show that simple excision of the cervical rib with scalenectomy via supraclavicular approach, together with arterial reconstruction (if required) is adequate for arterial vascular complications resulting from thoracic outlet compression. Patients with severe distal disease may require other adjunct procedures like dorsal sympathectomy or prostaglandin infusions along with proximal reconstruction.
Primary squamous cell carcinoma of the stomach
Authors: Chan Alexander Pak‐Hin , Wong Shun , Mak Kwong‐Lin , Yung Virgil , Lee Kin‐Yip , Luk Hung‐To
Published: May 2006

Gastric cancer ranks as the fourth leading cause of cancer deaths in Hong Kong according to the Hong Kong Cancer Registry. The major histopathology of gastric cancer is adenocarcinoma. Squamous cell carcinoma of the stomach is an extremely rare entity. Only 85 cases of primary gastric squamous cell carcinoma worldwide have been reported in the literature. Diagnostic criteria have been set to differentiate from adenosquamous gastric carcinoma. The origin of this malignancy is not yet certain although there have been proposed theories as to its pathogenesis. It is difficult to clearly define its prognosis. The role of adjuvant chemotherapy and radiotherapy to long‐term survival still cannot be justified. We present probably the first reported case of pure primary squamous cell carcinoma of the stomach in Hong Kong in a 70‐year‐old man who underwent a distal radical gastrectomy in our department.
Stokes Mechanism of Drag Reduction
Authors: Bandyopadhyay Promode R.
Published: May 2006

The mechanism of drag reduction due to spanwise wall oscillation in a turbulent boundary layer is considered. Published measurements and simulation data are analyzed in light of Stokes’ second problem. A kinematic vorticity reorientation hypothesis of drag reduction is first developed. It is shown that spanwise oscillation seeds the near-wall region with oblique and skewed Stokes vorticity waves. They are attached to the wall and gradually align to the freestream direction away from it. The resulting Stokes layer has an attenuated nature compared to its laminar counterpart. The attenuation factor increases in the buffer and viscous sublayer as the wall is approached. The mean velocity profile at the condition of maximum drag reduction is similar to that due to polymer. The final mean state of maximum drag reduction due to turbulence suppression appears to be universal in nature. Finally, it is shown that the proposed kinematic drag reduction hypothesis describes the measurements significantly better than what current direct numerical simulation does.
Heat Exchangers for Fuel Cell and Hybrid System Applications
Authors: Magistri L. , Traverso A. , Massardo A. F. , Shah R. K.
Published: May 2006

The fuel cell system and fuel cell gas turbine hybrid system represent an emerging technology for power generation because of its higher energy conversion efficiency, extremely low environmental pollution, and potential use of some renewable energy sources as fuels. Depending upon the type and size of applications, from domestic heating to industrial cogeneration, there are different types of fuel cell technologies to be employed. The fuel cells considered in this paper are mainly the molten carbonate (MCFC) and the solid oxide (SOFC) fuel cells, while a brief overview is provided about the proton exchange membrane (PEMFC). In all these systems, heat exchangers play an important and critical role in the thermal management of the fuel cell itself and the boundary components, such as the fuel reformer (when methane or natural gas is used), the air preheating, and the fuel cell cooling. In this paper, the impact of heat exchangers on the performance of SOFC, MCFC gas turbine hybrid systems and PEMFC systems is investigated. Several options in terms of cycle layout and heat exchanger technology are discussed from the on-design, off-design and control perspectives. A general overview of the main issues related to heat exchangers performance, cost and durability is presented and the most promising configurations identified.
A Thermodynamic Analysis of Electricity and Hydrogen Co-Production Using a Solid Oxide Fuel Cell
Authors: Leal Elisângela M. , Brouwer Jack
Published: May 2006

This paper presents the electricity and hydrogen co-production concept, a methodology for the study of SOFC hydrogen co-production, and simulation results that address the impact of reformer placement in the cycle on system performance. The methodology is based on detailed thermodynamic and electrochemical analyses of the systems. A comparison is made between six specific cycle configurations, which use fuel cell heat to drive hydrogen production in a reformer using both external and internal reforming options. SOFC plant performance has been evaluated on the basis of methane fuel utilization efficiency and each component of the plant has been evaluated on the basis of second law efficiency. The analyses show that in all cases the exergy losses (irreversibilities) in the combustion chamber are the most significant losses in the cycle. Furthermore, for the same power output, the internal reformation option has the higher electrical efficiency and produces more hydrogen per unit of natural gas supplied. Electrical efficiency of the proposed cycles ranges from 41 to 44%, while overall efficiency (based on combined electricity and hydrogen products) ranges from 45 to 80%. The internal reforming case (steam-to-carbon ratio of 3.0) had the highest overall and electrical efficiency (80 and 45% respectively), but lower second law efficiency (61%), indicating potential for cycle improvements.
To Achieve the Best Performance Through Optimization of Gas Delivery and Current Collection in Solid Oxide Fuel Cells
Authors: Li P. W. , Chen S. P. , Chyu M. K.
Published: May 2006

Aimed at improving the maximum available power density in a planar-type solid oxide fuel cell, an analytical model is proposed in this work to find the optimum size of a current collector that collects the current from a specific active area of the electrode-electrolyte layer. Distributed three-dimensional current collectors in gas delivery field are designated to allow a larger area of the electrode-electrolyte layer to be active for electrochemical reaction compared to conventional designs that gas channels are separated by current collectors. It has been found that the optimal operating temperature of a planar-type solid oxide fuel cell might be around 850°C, if the sizes of the distributed current collectors and their control areas are optimized. Decreasing the size of both the current collector and its control area is advantageous in achieving a higher power density. Studies also show that the optimal sizes of the current collector and the current collection area investigated at 850°C and zero concentration polarization are applicable to situations of different operating temperatures, and different concentration polarizations. The optimization results of the sizes of current collectors and their control areas are relatively sensitive to the contact resistance between the current collectors and the electrodes of the fuel cell. Results of great significance are provided in the analysis, which will help designers to account for the variation of contact resistance in optimization designing of a bipolar plate of fuel cells.
Angle‐independent measure of motion for image‐based gating in 3D coronary angiography
Authors: Lehmann Glen C. , Holdsworth David W. , Drangova Maria
Published: May 2006

The role of three‐dimensional (3D) image guidance for interventional procedures and minimally invasive surgeries is increasing for the treatment of vascular disease. Currently, most interventional procedures are guided by two‐dimensional x‐ray angiography, but computed rotational angiography has the potential to provide 3D geometric information about the coronary arteries. The creation of 3D angiographic images of the coronary arteries requires synchronization of data acquisition with respect to the cardiac cycle, in order to minimize motion artifacts. This can be achieved by inferring the extent of motion from a patient's electrocardiogram (ECG) signal. However, a direct measurement of motion (from the 2D angiograms) has the potential to improve the 3D angiographic images by ensuring that only projections acquired during periods of minimal motion are included in the reconstruction. This paper presents an image‐based metric for measuring the extent of motion in 2D x‐ray angiographic images. Adaptive histogram equalization was applied to projection images to increase the sharpness of coronary arteries and the superior‐inferior component of the weighted centroid (SIC) was measured. The SIC constitutes an image‐based metric that can be used to track vessel motion, independent of apparent motion induced by the rotational acquisition. To evaluate the technique, six consecutive patients scheduled for routine coronary angiography procedures were studied. We compared the end of the SIC rest period to R‐waves detected in the patient's ECG and found a mean difference of . Two simultaneous angular positions were acquired and was detected for each position. There was no statistically significant difference between in the two simultaneously acquired angular positions. Thus we have shown the SIC to be independent of view angle, which is critical for rotational angiography. A preliminary image‐based gating strategy that employed the SIC was compared to an ECG‐based gating strategy in a porcine model. The image‐based gating strategy selected 61 projection images, compared to 45 selected by the ECG‐gating strategy. Qualitative comparison revealed that although both the SIC‐based and ECG‐gated reconstructions decreased motion artifact compared to reconstruction with no gating, the SIC‐based gating technique increased the conspicuity of smaller vessels when compared to ECG gating in maximum intensity projections of the reconstructions and increased the sharpness of a vessel cross section in multi‐planar reformats of the reconstruction.
Intraoperative radiation therapy using mobile electron linear accelerators: Report of AAPM Radiation Therapy Committee Task Group No. 72
Authors: Beddar A. Sam , Biggs Peter J. , Chang Sha , Ezzell Gary A. , Faddegon Bruce A. , Hensley Frank W. , Mills Michael D.
Published: May 2006

Intraoperative radiation therapy (IORT) has been customarily performed either in a shielded operating suite located in the operating room (OR) or in a shielded treatment room located within the Department of Radiation Oncology. In both cases, this cancer treatment modality uses stationary linear accelerators. With the development of new technology, mobile linear accelerators have recently become available for IORT. Mobility offers flexibility in treatment location and is leading to a renewed interest in IORT. These mobile accelerator units, which can be transported any day of use to almost any location within a hospital setting, are assembled in a nondedicated environment and used to deliver IORT. Numerous aspects of the design of these new units differ from that of conventional linear accelerators. The scope of this Task Group (TG‐72) will focus on items that particularly apply to mobile IORT electron systems. More specifically, the charges to this Task Group are to (i) identify the key differences between stationary and mobile electron linear accelerators used for IORT, (ii) describe and recommend the implementation of an IORT program within the OR environment, (iii) present and discuss radiation protection issues and consequences of working within a nondedicated radiotherapy environment, (iv) describe and recommend the acceptance and machine commissioning of items that are specific to mobile electron linear accelerators, and (v) design and recommend an efficient quality assurance program for mobile systems.
Neurobiological Substrates of Dread
Authors: Berns Gregory S. , Chappelow Jonathan , Cekic Milos , Zink Caroline F. , Pagnoni Giuseppe , Martin-Skurski Megan E.
Published: May 2006

Given the choice of waiting for an adverse outcome or getting it over with quickly, many people choose the latter. Theoretical models of decision-making have assumed that this occurs because there is a cost to waiting—i.e., dread. Using functional magnetic resonance imaging, we measured the neural responses to waiting for a cutaneous electric shock. Some individuals dreaded the outcome so much that, when given a choice, they preferred to receive more voltage rather than wait. Even when no decision was required, these extreme dreaders were distinguishable from those who dreaded mildly by the rate of increase of neural activity in the posterior elements of the cortical pain matrix. This suggests that dread derives, in part, from the attention devoted to the expected physical response and not simply from fear or anxiety. Although these differences were observed during a passive waiting procedure, they correlated with individual behavior in a subsequent choice paradigm, providing evidence for a neurobiological link between the experienced disutility of dread and subsequent decisions about unpleasant outcomes.
Interstellar Chemistry Recorded in Organic Matter from Primitive Meteorites
Authors: Busemann Henner , Young Andrea F. , Alexander Conel M. O'D. , Hoppe Peter , Mukhopadhyay Sujoy , Nittler Larry R.
Published: May 2006

Organic matter in extraterrestrial materials has isotopic anomalies in hydrogen and nitrogen that suggest an origin in the presolar molecular cloud or perhaps in the protoplanetary disk. Interplanetary dust particles are generally regarded as the most primitive solar system matter available, in part because until recently they exhibited the most extreme isotope anomalies. However, we show that hydrogen and nitrogen isotopic compositions in carbonaceous chondrite organic matter reach and even exceed those found in interplanetary dust particles. Hence, both meteorites (originating from the asteroid belt) and interplanetary dust particles (possibly from comets) preserve primitive organics that were a component of the original building blocks of the solar system.
Genetic and Biochemical Evidence for the Involvement of a Molybdenum-Dependent Enzyme in One of the Selenite Reduction Pathways ofRhodobacter sphaeroidesf. sp.denitrificansIL106
Authors: Pierru Bénédicte , Grosse Sandrine , Pignol David , Sabaty Monique
Published: May 2006

Selenite reduction inRhodobacter sphaeroidesf. sp.denitrificanswas observed under photosynthetic conditions, following a 100-h lag period. This adaptation period was suppressed if the medium was inoculated with a culture previously grown in the presence of selenite, suggesting that selenite reduction involves an inducible enzymatic pathway. A transposon library was screened to isolate mutants affected in selenite reduction. Of the eight mutants isolated, two were affected in molybdenum cofactor synthesis. ThesemoaAandmogAmutants showed an increased duration of the lag phase and a decreased rate of selenite reduction. When grown in the presence of tungstate, a well-known molybdenum-dependent enzyme (molybdoenzyme) inhibitor, the wild-type strain displayed the same phenotype. The addition of tungstate in the medium or the inactivation of the molybdocofactor synthesis induced a decrease of 40% in the rate of selenite reduction. These results suggest that several pathways are involved and that one of them involves a molybdoenzyme. Although addition of nitrate or dimethyl sulfoxide (DMSO) to the medium increased the selenite reduction activity of the culture, neither the periplasmic nitrate reductase NAP nor the DMSO reductase is the implicated molybdoenzyme, since thenapAanddmsAmutants, with expression of nitrate reductase and DMSO reductase, respectively, eliminated, were not affected by selenite reduction. A role for the biotine sulfoxide reductase, another characterized molybdoenzyme, is unlikely, since its overexpression in a defective strain did not restore the selenite reduction activity.
Manganese(II)-Oxidizing
Bacillus
Spores in Guaymas Basin Hydrothermal Sediments and Plumes
Authors: Dick Gregory J. , Lee Yifan E. , Tebo Bradley M.
Published: May 2006

Microbial oxidation and precipitation of manganese at deep-sea hydrothermal vents are important oceanic biogeochemical processes, yet nothing is known about the types of microorganisms or mechanisms involved. Here we report isolation of a number of diverse spore-forming Mn(II)-oxidizing
Bacillus
species from Guaymas Basin, a deep-sea hydrothermal vent environment in the Gulf of California, where rapid microbially mediated Mn(II) oxidation was previously observed.
mnxG
multicopper oxidase genes involved in Mn(II) oxidation were amplified from all Mn(II)-oxidizing
Bacillus
spores isolated, suggesting that a copper-mediated mechanism of Mn(II) oxidation could be important at deep-sea hydrothermal vents. Phylogenetic analysis of 16S rRNA and
mnxG
genes revealed that while many of the deep-sea Mn(II)-oxidizing
Bacillus
species are very closely related to previously recognized isolates from coastal sediments, other organisms represent novel strains and clusters. The growth and Mn(II) oxidation properties of these
Bacillus
species suggest that in hydrothermal sediments they are likely present as spores that are active in oxidizing Mn(II) as it emerges from the seafloor.
Plasmid pCAR3 Contains Multiple Gene Sets Involved in the Conversion of Carbazole to Anthranilate
Authors: Urata Masaaki , Uchimura Hiromasa , Noguchi Haruko , Sakaguchi Tomoya , Takemura Tetsuo , Eto Kaori , Habe Hiroshi , Omori Toshio , Yamane Hisakazu , Nojiri Hideaki
Published: May 2006

The carbazole degradative
car-I
gene cluster (
carAaIBaIBbICIAcI
) of
Sphingomonas
sp. strain KA1 is located on the 254-kb circular plasmid pCAR3. Carbazole conversion to anthranilate is catalyzed by carbazole 1,9a-dioxygenase (CARDO; CarAaIAcI),
meta
-cleavage enzyme (CarBaIBbI), and hydrolase (CarCI). CARDO is a three-component dioxygenase, and CarAaI and CarAcI are its terminal oxygenase and ferredoxin components. The
car-I
gene cluster lacks the gene encoding the ferredoxin reductase component of CARDO. In the present study, based on the draft sequence of pCAR3, we found multiple carbazole degradation genes dispersed in four loci on pCAR3, including a second copy of the
car
gene cluster (
carAaIIBaIIBbIICIIAcII
) and the ferredoxin/reductase genes
fdxI-fdrI
and
fdrII
. Biotransformation experiments showed that FdrI (or FdrII) could drive the electron transfer chain from NAD(P)H to CarAaI (or CarAaII) with the aid of ferredoxin (CarAcI, CarAcII, or FdxI). Because this electron transfer chain showed phylogenetic relatedness to that consisting of putidaredoxin and putidaredoxin reductase of the P450cam monooxygenase system of
Pseudomonas putida
, CARDO systems of KA1 can be classified in the class IIA Rieske non-heme iron oxygenase system. Reverse transcription-PCR (RT-PCR) and quantitative RT-PCR analyses revealed that two
car
gene clusters constituted operons, and their expression was induced when KA1 was exposed to carbazole, although the
fdxI-fdrI
and
fdrII
genes were expressed constitutively. Both terminal oxygenases of KA1 showed roughly the same substrate specificity as that from the well-characterized carbazole degrader
Pseudomonas resinovorans
CA10, although slight differences were observed.
Levels of Polyamines and Kinetic Characterization of Their Uptake in the Soybean Pathogen
Phytophthora sojae
Authors: Chibucos M. Constantine , Morris Paul F.
Published: May 2006

Polyamines are ubiquitous biologically active aliphatic cations that are at least transiently available in the soil from decaying organic matter. Our objectives in this study were to characterize polyamine uptake kinetics in
Phytophthora sojae
zoospores and to quantify endogenous polyamines in hyphae, zoospores, and soybean roots. Zoospores contained 10 times more free putrescine than spermidine, while hyphae contained only 4 times as much free putrescine as spermidine. Zoospores contained no conjugated putrescine, but conjugated spermidine was present. Hyphae contained both conjugated putrescine and spermidine at levels comparable to the hyphal free putrescine and spermidine levels. In soybean roots, cadaverine was the most abundant polyamine, but only putrescine efflux was detected. The selective efflux of putrescine suggests that the regulation of polyamine availability is part of the overall plant strategy to influence microbial growth in the rhizosphere. In zoospores, uptake experiments with [1,4-
14
C]putrescine and [1,4-
14
C]spermidine confirmed the existence of high-affinity polyamine transport for both polyamines. Putrescine uptake was reduced by high levels of exogenous spermidine, but spermidine uptake was not reduced by exogenous putrescine. These observations suggest that
P. sojae
zoospores express at least two high-affinity polyamine transporters, one that is spermidine specific and a second that is putrescine specific or putrescine preferential. Disruption of polyamine uptake or metabolism has major effects on a wide range of cellular activities in other organisms and has been proposed as a potential control strategy for
Phytophthora
. Inhibition of polyamine uptake may be a means of reducing the fitness of the zoospore along with subsequent developmental stages that precede infection.
Lactococcin Q, a Novel Two-Peptide Bacteriocin Produced by
Lactococcus lactis
QU 4
Authors: Zendo Takeshi , Koga Shoko , Shigeri Yasushi , Nakayama Jiro , Sonomoto Kenji
Published: May 2006

A bacteriocin-producing strain,
Lactococcus lactis
QU 4, was isolated from corn. The bacteriocin, termed lactococcin Q, showed antibacterial activity only against
L. lactis
strains among a wide range of gram-positive indicator strains tested. Lactococcin Q was purified by acetone precipitation, cation exchange chromatography, and reverse-phase chromatography. Lactococcin Q consisted of two peptides, α and β, whose molecular masses were determined to be 4,260.43 Da and 4,018.36 Da, respectively. Amino acid and DNA sequencing analyses revealed that lactococcin Q was a novel two-peptide bacteriocin, homologous to lactococcin G. Comparative study using chemically synthesized lactococcin Q (Qα plus Qβ) and lactococcin G (Gα plus Gβ) clarified that hybrid combinations (Qα plus Gβ and Gα plus Qβ) as well as original combinations showed antibacterial activity, although each single peptide showed no significant activity. These four pairs of lactococcin peptides acted synergistically at a 1:1 molar ratio and exhibited identical antibacterial spectra but differed in MIC. The MIC of Qα plus Gβ was 32 times higher than that of Qα plus Qβ, suggesting that the difference in β peptides was important for the intensity of antibacterial activity.
Dissemination of Fluoroquinolone-Resistant
Campylobacter
spp. within an Integrated Commercial Poultry Production System
Authors: Idris Umelaalim , Lu Jingrang , Maier Marie , Sanchez Susan , Hofacre Charles L. , Harmon Barry G. , Maurer John J. , Lee Margie D.
Published: May 2006

While characterizing the intestinal bacterial community of broiler chickens, we detected ε-proteobacterial DNA in the ilea of 3-day-old commercial broiler chicks (J. Lu, U. Idris, B. Harmon, C. Hofacre, J. J. Maurer, and M. D. Lee, Appl. Environ. Microbiol.
69:
6816-6824, 2003). The sequences exhibited high levels of similarity to
Campylobacter jejuni
and
Campylobacter coli
sequences, suggesting that chickens can carry
Campylobacter
at a very young age.
Campylobacter
sp. was detected by PCR in all samples collected from the ilea of chicks that were 3 to 49 days old; however, it was detected only in the cecal contents of chickens that were at least 21 days old. In order to determine whether the presence of
Campylobacter
DNA in young chicks was due to ingestion of the bacteria in food or water, we obtained commercial broiler hatching eggs, which were incubated in a research facility until the chicks hatched. DNA sequencing of the amplicons resulting from
Campylobacter
-specific 16S PCR performed with the ileal, cecal, and yolk contents of the day-of-hatching chicks revealed that
Campylobacter
DNA was present before the chicks consumed food or water. The 16S rRNA sequences exhibited 99% similarity to
C. jejuni
and
C. coli
sequences and 95 to 98% similarity to sequences of other thermophilic
Campylobacter
species, such as
C. lari
and
C. upsaliensis
. The presence of
C. coli
DNA was detected by specific PCR in the samples from chicks obtained from a commercial hatchery; however, no
Campylobacter
was detected by culturing. In order to determine whether the same strains of bacteria were present in multiple levels of the integrator, we cultured
Campylobacter
sp. from a flock of broiler breeders and their 6-week-old progeny that resided on a commercial broiler farm. The broiler breeders had been given fluoroquinolone antibiotics, and we sought to determine whether the same fluoroquinolone-resistant strain was present in their progeny. The isolates were typed by pulsed-field gel electrophoresis, which confirmed that the parental and progeny flocks contained the same strain of fluoroquinolone-resistant
C. coli
. These data indicate that resistant
C. coli
can be present in multiple levels of an integrated poultry system and demonstrated that molecular techniques or more sensitive culture methods may be necessary to detect early colonization by
Campylobacter
in broiler chicks.
Characterization of an Exo-β-1,3-Galactanase from
Clostridium thermocellum
Authors: Ichinose Hitomi , Kuno Atsushi , Kotake Toshihisa , Yoshida Makoto , Sakka Kazuo , Hirabayashi Jun , Tsumuraya Yoichi , Kaneko Satoshi
Published: May 2006

A gene encoding an exo-β-1,3-galactanase from
Clostridium thermocellum
, Ct1,3Gal43A, was isolated. The sequence has similarity with an exo-β-1,3-galactanase of
Phanerochaete chrysosporium
(Pc1,3Gal43A). The gene encodes a modular protein consisting of an N-terminal glycoside hydrolase family 43 (GH43) module, a family 13 carbohydrate-binding module (CBM13), and a C-terminal dockerin domain. The gene corresponding to the GH43 module was expressed in
Escherichia coli
, and the gene product was characterized. The recombinant enzyme shows optimal activity at pH 6.0 and 50°C and catalyzes hydrolysis only of β-1,3-linked galactosyl oligosaccharides and polysaccharides. High-performance liquid chromatography analysis of the hydrolysis products demonstrated that the enzyme produces galactose from β-1,3-galactan in an exo-acting manner. When the enzyme acted on arabinogalactan proteins (AGPs), the enzyme produced oligosaccharides together with galactose, suggesting that the enzyme is able to accommodate a β-1,6-linked galactosyl side chain. The substrate specificity of the enzyme is very similar to that of Pc1,3Gal43A, suggesting that the enzyme is an exo-β-1,3-galactanase. Affinity gel electrophoresis of the C-terminal CBM13 did not show any affinity for polysaccharides, including β-1,3-galactan. However, frontal affinity chromatography for the CBM13 indicated that the CBM13 specifically interacts with oligosaccharides containing a β-1,3-galactobiose, β-1,4-galactosyl glucose, or β-1,4-galactosyl
N
-acetylglucosaminide moiety at the nonreducing end. Interestingly, CBM13 in the C terminus of Ct1,3Gal43A appeared to interfere with the enzyme activity toward β-1,3-galactan and α-
l
-arabinofuranosidase-treated AGP.