bluuebunny/crossref_metadata_2025 huggingface dataset:
Permanent-magnet-free stabilization and sensitivity tailoring of magnetoresistive field sensors
Authors: Halloran S. T. , da Silva F. C. S. , Fardi H. Z. , Pappas D. P.
Published: August 2007

We have exploited the coupling across a ruthenium spacer between a ferromagnetic and an antiferromagnetic layer to stabilize the magnetization in a given direction and tailor the magnetic sensitivity of the sensor for various applications. Ruthenium is used as the nonmagnetic coupling layer and is self-aligned with the ferromagnetic free layer and antiferromagnetic pinning layer, and the thickness is varied to change the slope of the transfer curve in the linear region, i.e., sensitivity. This simple technique is shown to increase the dynamic range of anisotropic magnetoresistive sensors without additional lithography.
Femtosecond cellular transfection using a nondiffracting light beam
Authors: Tsampoula X. , Garcés-Chávez V. , Comrie M. , Stevenson D. J. , Agate B. , Brown C. T. A. , Gunn-Moore F. , Dholakia K.
Published: August 2007

The ability to permeate selectively the cell membrane and introduce therapeutic agents is a key goal in cell biology. Optical transfection is a powerful methodology but requires exact focusing due to the required two-photon power density. The authors use a Bessel beam that obviates the need to locate precisely the cell membrane, permitting two-photon excitation along a line leading to cell transfection. Assuming a minimum efficiency of 20%, the Bessel beam offers transfection at axial distances 20 times greater than that of its Gaussian equivalent. Furthermore, the authors demonstrate cell transfection beyond obstacles due to the self-healing nature of the Bessel beam.
Phonon-assisted stimulated emission from pendeoepitaxy GaN stripes grown on 6H-SiC substrates
Authors: Chang Y. C. , Li Y.-L. , Thomson D. B. , Davis R. F.
Published: August 2007

Phonon-assisted stimulated emission has been demonstrated by photopumping GaN stripes grown via pendeoepitaxy on 6H-SiC (0001) substrates. Transverse-electric-polarized emission with well-defined Fabry-Pérot modes located at one longitudinal optical phonon energy (90meV) below the band gap of GaN was observed at 77K. An effective refractive index of 8.578 was obtained using a cavity length of 13.3μm and a mode spacing of 0.6nm. This value is significantly higher than the value previously reported in the literature using ellipsometry, which indicates that the absorption loss is more severe during lasing when the excess carrier concentration is very high.
Voltage induced ultrasharp current jump and magnetic tunability of CaMnO3−δ∕La0.69Ca0.31MnO3 heterojunction
Authors: Xiong C. M. , Zhao Y. G. , Guo S. M. , Xie B. T. , Huang W. G. , Kou Z. Q. , Cheng Z. H.
Published: August 2007

The authors report the current-voltage characteristics of CaMnO3−δ∕La0.69Ca0.31MnO3 heterojunctions prepared under different oxygen pressures. The most interesting observation is that the heterojunctions made under low oxygen pressure shows an ultrasharp current jump in the current-voltage curves and the nonlinear coefficient can reach ∼2×104. They also show remarkable magnetoresistance. The results can be understood in terms of the oxygen vacancy related defects at the junction interface. This work shows that all-manganite-based heterojunctions can show giant nonlinear coefficient, which may have potential applications.
Spin transfer switching in current-perpendicular-to-plane spin valve observed by magneto-optical Kerr effect using visible light
Authors: Aoshima Ken-ichi , Funabashi Nobuhiko , Machida Kenji , Miyamoto Yasuyoshi , Kawamura Norikazu , Kuga Kiyoshi , Shimidzu Naoki , Sato Fumio , Kimura Takashi , Otani Yoshichika
Published: August 2007

The authors have succeeded in optically observing the spin transfer switching (STS) in a current-perpendicular-to-plane spin-valve device. The device consists of three spin-valve elements, each of which comprises of a transparent top electrode, free and pinned magnetic layers separated by a copper spacer, and a bottom copper electrode. Despite a relatively large device resistance, spin transfer switching of the free layer was carried out using the spin injection from the transparent top electrode. Magneto-optical Kerr effect measurements performed through the transparent top electrode show clear changes in the signal synchronized with the resistance change as a result of the STS.
Single-component reflecting objective for low-temperature spectroscopy in the entire visible region
Authors: Fujiyoshi Satoru , Fujiwara Masanori , Kim Changman , Matsushita Michio , van Oijen Antoine M. , Schmidt Jan
Published: August 2007

A single-component reflecting objective was constructed for low-temperature spectroscopy with optimal imaging and transmission properties at all visible wavelengths. The performance of the objective immersed in superfluid helium at a temperature of 1.5K was tested by comparing dark-field images of uncolored polymer beads taken at wavelengths of 400 and 800nm. Under conditions optimized for imaging at both wavelengths, the size of the image is <1.3 times of the diffraction limit. The objective collects emission from a point source at focus with a solid angle of 0.32πsr.
4
H
SiC betavoltaic powered temperature transducer
Authors: Chandrashekhar M. V. S. , Duggirala Rajesh , Spencer Michael G. , Lal Amit
Published: August 2007

The change in open-circuit voltage of a 4H SiC p-n diode betavoltaic cell in response to temperature was used to sense temperature. A linear sensitivity of 2.7mV∕K was obtained from 24to86°C. This was achieved with only 2.5μCi of active nickel-63 as the β source, giving a short circuit current of 21pA, a low-enough activity for civilian applications. The measured sensitivity of 2.7mV∕K was lower than the 5.5mV∕K predicted from the theory. The 28GΩ shunt resistance of the betavoltaic cell was used to explain the lower sensitivity.
Effects of energetic ion particles on friction of diamond-like carbon
Authors: Wang K. , Liang H. , Martin J. M. , Le Mogne T.
Published: August 2007

The authors demonstrate that energetic argon ions introduce phase transformation of a diamond- like carbon film. Inside an ultrahigh vacuum chamber, energetic Ar ions of 5keV were generated using an x-ray photon spectroscopy. After ion bombardment, x-ray photon spectroscopy (XPS) and friction tests were conducted in situ. The ex situ surface morphological analysis using an atomic force microscope and the multiple-peaks deconvolution of the C 1s XPS peak indicate that the changing ratio of sp2 and sp3 hybridization of carbon dominates the film friction. The authors conclude that the friction of the diamon dlike carbon film against itself depends on the carbon phase, not on the film surface roughness.
Dingle temperatures for a two-band model: Application to the two-dimensional electron gas on silicon (111)
Authors: Gold A. , Fabie L. , Dolgopolov V. T.
Published: August 2007

For zero temperature, we present theoretical results for the Dingle temperatures of a two-dimensional electron gas with two occupied bands. For impurity scattering, we apply their calculation to a two-band model for valley degeneracy gv=2 and gv=4 proposed recently for silicon (111). Taking into account the density of states and screening effects of the two electron gases, we predict huge differences for the Dingle temperature of the two bands and a strong density dependence for the Dingle temperature of the first band due to screening by the second band. The mobility of the two-band model shows a strong density dependence.
Different acceptor behaviors in two-dimensional hole gas system formed in Mn-doped GaAs∕p-AlGaAs ferromagnetic heterostructures
Authors: Wang Jiqing , Lv Bin , Mao Huibing , Zhao Qiang , Yu Jianguo , Liu Yan , Zhang Yong , Zhu Ziqiang , Xing Huaizhong
Published: August 2007

The authors investigated the ferromagnetic property of dual acceptors (Be and Mn) doped GaAs∕AlGaAs heterostructures by means of numerical self-consistent field calculation. The dependence of the magnetic behavior on both acceptor doping concentrations and modes was studied in the two-dimensional hole gas system. The results show different dependences of Curie temperature on the concentration of each acceptor, which is attributed to different doping conditions and mechanisms. In addition, the ferromagnetic transition temperature can be increased by about 70K as a result of introducing Be δ-doping layer in AlGaAs barrier, as compared with that for Be bulk doping. The theoretical results indicate that double acceptor δ-doped ferromagnetic heterostructures have potential advantage in the realm of spintronic application.
Embryonic stem cells in companion animals (horses, dogs and cats): present status and future prospects
Authors: Tecirlioglu R. Tayfur , Trounson Alan O.
Published: August 2007

Reproductive technologies have made impressive advances since the 1950s owing to the development of new and innovative technologies. Most of these advances were driven largely by commercial opportunities and the potential improvement of farm livestock production and human health. Companion animals live long and healthy lives and the greatest expense for pet owners are services related to veterinary care and healthcare products. The recent development of embryonic stem cell and nuclear transfer technology in primates and mice has enabled the production of individual specific embryonic stem cell lines in a number of species for potential cell-replacement therapy. Stem cell technology is a fast-developing area in companion animals because many of the diseases and musculoskeletal injuries of cats, dogs and horses are similar to those in humans. Nuclear transfer-derived stem cells may also be selected and directed into differentiation pathways leading to the production of specific cell types, tissues and, eventually, even organs for research and transplantaton. Furthermore, investigations into the treatment of inherited or acquired pathologies have been performed mainly in mice. However, mouse models do not always faithfully represent the human disease. Naturally occurring diseases in companion animals can be more ideal as disease models of human genetic and acquired diseases and could help to define the potential therapeutic efficiency and safety of stem cell therapies. In the present review, we focus on the economic implications of companion animals in society, as well as recent biotechnological progress that has been made in horse, dog and cat embryonic stem cell derivation.
Electrophysiological signatures of resting state networks in the human brain
Authors: Mantini D. , Perrucci M. G. , Del Gratta C. , Romani G. L. , Corbetta M.
Published: August 2007

Functional neuroimaging and electrophysiological studies have documented a dynamic baseline of intrinsic (not stimulus- or task-evoked) brain activity during resting wakefulness. This baseline is characterized by slow (<0.1 Hz) fluctuations of functional imaging signals that are topographically organized in discrete brain networks, and by much faster (1–80 Hz) electrical oscillations. To investigate the relationship between hemodynamic and electrical oscillations, we have adopted a completely data-driven approach that combines information from simultaneous electroencephalography (EEG) and functional magnetic resonance imaging (fMRI). Using independent component analysis on the fMRI data, we identified six widely distributed resting state networks. The blood oxygenation level-dependent signal fluctuations associated with each network were correlated with the EEG power variations of delta, theta, alpha, beta, and gamma rhythms. Each functional network was characterized by a specific electrophysiological signature that involved the combination of different brain rhythms. Moreover, the joint EEG/fMRI analysis afforded a finer physiological fractionation of brain networks in the resting human brain. This result supports for the first time in humans the coalescence of several brain rhythms within large-scale brain networks as suggested by biophysical studies.
Modification of adverse inflammation is required to cure new-onset type 1 diabetic hosts
Authors: Koulmanda Maria , Budo Ejona , Bonner-Weir Susan , Qipo Andi , Putheti Prabhakar , Degauque Nicolas , Shi Hang , Fan Zhigang , Flier Jeffrey S. , Auchincloss Hugh , Zheng Xin Xiao , Strom Terry B.
Published: August 2007

In nonobese diabetic (NOD) mice with overt new-onset type 1 diabetes mellitus (T1DM), short-term treatment with a “triple-therapy” regimen [rapamycin plus agonist IL-2-related and antagonist-type, mutant IL-15-related Ig fusion proteins (IL-2.Ig and mutIL-15.Ig)] halts autoimmune destruction of insulin-producing beta cells and restores both euglycemia and immune tolerance to beta cells. Increases in the mass of insulin-producing beta cells or circulating insulin levels were not linked to the restoration of euglycemia. Instead, the restoration of euglycemia was linked to relief from an inflammatory state that impaired the host's response to insulin. Both restoration of immune tolerance to beta cells and relief from the adverse metabolic effects of an inflammatory state in insulin-sensitive tissues appear essential for permanent restoration of normoglycemia in this T1DM model. Thus, this triple-therapy regimen, possessing both tolerance-inducing and select antiinflammatory properties, may represent a prototype for therapies able to restore euglycemia and self-tolerance in T1DM.
The AP1-dependent secretion of galectin-1 by Reed–Sternberg cells fosters immune privilege in classical Hodgkin lymphoma
Authors: Juszczynski Przemyslaw , Ouyang Jing , Monti Stefano , Rodig Scott J. , Takeyama Kunihiko , Abramson Jeremy , Chen Wen , Kutok Jeffery L. , Rabinovich Gabriel A. , Shipp Margaret A.
Published: August 2007

Classical Hodgkin lymphomas (cHLs) contain small numbers of neoplastic Reed–Sternberg (RS) cells within an extensive inflammatory infiltrate that includes abundant T helper (Th)-2 and T regulatory (T
reg
) cells. The skewed nature of the T cell infiltrate and the lack of an effective host antitumor immune response suggest that RS cells use potent mechanisms to evade immune attack. In a screen for T cell-inhibitory molecules in cHL, we found that RS cells selectively overexpressed the immunoregulatory glycan-binding protein, galectin-1 (Gal1), through an AP1-dependent enhancer. In cocultures of activated T cells and Hodgkin cell lines, RNAi-mediated blockade of RS cell Gal1 increased T cell viability and restored the Th1/Th2 balance. In contrast, Gal1 treatment of activated T cells favored the secretion of Th2 cytokines and the expansion of CD4
+
CD25
high
FOXP3
+
T
reg
cells. These data directly implicate RS cell Gal1 in the development and maintenance of an immunosuppressive Th2/T
reg
-skewed microenvironment in cHL and provide the molecular basis for selective Gal1 expression in RS cells. Thus, Gal1 represents a potential therapeutic target for restoring immune surveillance in cHL.
Comparison of Automated Strategies for Surveillance of Nosocomial Bacteremia
Authors: Bellini Cristina , Petignat Christiane , Francioli Patrick , Wenger Aline , Bille Jacques , Klopotov Adriana , Vallet Yannick , Patthey René , Zanetti Giorgio
Published: August 2007

Objective.

Surveillance of nosocomial bloodstream infection (BSI) is recommended, but time-consuming. We explored strategies for automated surveillance.

Methods.

Cohort study. We prospectively processed microbiological and administrative patient data with computerized algorithms to identify contaminated blood cultures, community-acquired BSI, and hospital-acquired BSI and used algorithms to classify the latter on the basis of whether it was a catheter-associated infection. We compared the automatic classification with an assessment (71% prospective) of clinical data.

Setting.

An 850-bed university hospital.

Participants.

All adult patients admitted to general surgery, internal medicine, a medical intensive care unit, or a surgical intensive care unit over 3 years.

Results.

The results of the automated surveillance were 95% concordant with those of classical surveillance based on the assessment of clinical data in distinguishing contamination, community-acquired BSI, and hospital-acquired BSI in a random sample of 100 cases of bacteremia. The two methods were 74% concordant in classifying 351 consecutive episodes of nosocomial BSI with respect to whether the BSI was catheter-associated. Prolonged episodes of BSI, mostly fungemia, that were counted multiple times and incorrect classification of BSI clinically imputable to catheter infection accounted for 81% of the misclassifications in automated surveillance. By counting episodes of fungemia only once per hospital stay and by considering all cases of coagulase-negative staphylococcal BSI to be catheter-related, we improved concordance with clinical assessment to 82%. With these adjustments, automated surveillance for detection of catheter-related BSI had a sensitivity of 78% and a specificity of 93%; for detection of other types of nosocomial BSI, the sensitivity was 98% and the specificity was 69%.

Conclusion.

Automated strategies are convenient alternatives to manual surveillance of nosocomial BSI.
The Ethics of Infection Control: Philosophical Frameworks
Authors: Bryan Charles S. , Call Theresa J. , Elliott Kevin C.
Published: August 2007

Recent developments that are relevant to the ethics of infection control include the patient safety movement, the appearance of new diseases (notably, severe acute respiratory syndrome) that pose threats to healthcare workers, data confirming the suspicion that infection control measures such as isolation may compromise patient care, and, in philosophy, renewed interest in virtue ethics and communitarianism. We review general ethical frameworks and relevant vocabulary for infection control practitioners and hospital epidemiologists. Frameworks for the ethics of infection control resemble those of public health more than those of clinical medicine but embrace elements of both. The optimum framework, we suggest, takes into account a virtue-based communitarianism. The virtue ethics movement stresses the need to consider not only rules and outcomes but also the character of the individual(s) involved. Communitarianism emphasizes the well-being and values of local communities, best determined by shared, democratic decision making among stakeholders. Brief discussions of 15 consecutive cases illustrate the extent to which the daily practice of infection control poses problems heavily freighted with ethical overtones.
Risk Factors for Surgical Site Infection Complicating Laminectomy
Authors: Friedman N. Deborah , Sexton Daniel J. , Connelly Sarah M. , Kaye Keith S.
Published: August 2007

Objective.

To examine risk factors for surgical site infection (SSI) following spinal surgery and to analyze the associations between a surgeon's years of operating experience and surgical specialty and patients' SSI risk.

Design.

Case-control study.

Setting.

A tertiary care facility and a community hospital in Durham, North Carolina.

Patients.

Each case patient who developed an SSI complicating laminectomy was matched with 2 noninfected control patients by hospital, year of surgery, and National Nosocomial Infection Surveillance System risk index score.

Results.

Forty-one case patients with SSI complicating laminectomy and 82 matched control patients were analyzed. Nonwhite race, diabetes and an elevated body mass index (BMI) were more common among case patients than among control patients. Subjects with a BMI greater than 35 were more likely to undergo a prolonged procedure, compared with case patients who had a BMI of 35 or less. The SSI rate for patients operated on by neurosurgeons was 28%, compared with 43% for patients operated on by orthopedic surgeons (odds ratio [OR], 0.5;P= .12). The number of years of operating experience were not associated with SSI risk. Multivariate analysis revealed diabetes (OR, 4.2 [95% confidence interval {CI}, 1.1-16.3];P= .04), BMI greater than 35 (OR, 7.1 [95% CI, 1.8-28.3];P= .005), and laminectomy at a level other than cervical (OR, 6.7 [95% CI, 1.4-33.3];P= .02) as independent risk factors for SSI following laminectomy.

Conclusion.

Diabetes, obesity, and laminectomy at a level other than cervical are independent risk factors for SSI following laminectomy. Preoperative weight loss and tight perioperative control of blood glucose levels may reduce the risk of SSI in laminectomy patients.
Risk of Bioaerosol Contamination With Aspergillus Species Before and After Cleaning in Rooms Filtered With High-Efficiency Particulate Air Filters That House Patients With Hematologic Malignancy
Authors: Lee Linda D. , Berkheiser Matthew , Jiang Ying , Hackett Brenda , Hachem Ray Y. , Chemaly Roy F. , Raad Issam I.
Published: August 2007

Objective.

To examine the impact of cleaning and directional airflow on environmental contamination with Aspergillus species in hospital rooms filtered with high-efficiency particulate air (HEPA) filters that house patients with hematologic malignancy.

Design.

Detailed environmental assessment.

Setting.

A 475-bed tertiary cancer center in the southern United States.

Methods.

From April to October 2004, 1,258 surface samples and 627 bioaerosol samples were obtained from 74 HEPA-filtered rooms (in addition, 88 outdoor bioaerosol samples were obtained). Samples were collected from rooms cleaned within 1 hour after patient discharge and from rooms before cleaning. Positive and negative airflows were evaluated using air-current tubes at entrances to patient rooms.

Results.

Of 1,258 surface samples, 3.3% were positive for Aspergillus species. Univariate analysis showed no relationship between cleaning status and occurrence of Aspergillus species. Of 627 bioaerosol samples, 7.3% were positive for Aspergillus species. Multiple logistic analysis revealed independently significant associations with detection of Aspergillus species. Cleaned rooms positive for Aspergillus species had a higher geometric mean density of colonies than that of rooms sampled before cleaning (18.9 vs 5.5 colony-forming units [cfu] per cubic meter; P = .0047). Rooms with positive airflow had a detection rate for bioaerosol samples equivalent to that of rooms with negative airflow (7.3% vs 7.8%; P = .8). There was no significant difference in the density of Aspergillus species between rooms with negative airflow and rooms with positive airflow (12.5 vs 8.4 cfu/m3; P = .33).

Conclusions.

Concentration of bioaerosol contamination with Aspergillus species was increased in rooms sampled 1 hour after cleaning compared with rooms sampled before cleaning, suggesting a possible correlation between reentrained bioaerosols (ie, those suspended by activity in the room) after cleaning and the risk of nosocomial invasive aspergillosis.
Active Surveillance of Legionnaires Disease During a Prospective Observational Study of Community-and Hospital-Acquired Pneumonia
Authors: Leoni Erica , Sacchetti Rossella , Aporti Manuela , Lazzari Claudio , Donati Manuela , Zanetti Franca , De Luca Giovanna , Finzi Gian Franco , Legnani Pier Paolo
Published: August 2007

A prospective surveillance study of legionnaires disease and an environmental survey of Legionella species were performed simultaneously in a general hospital. During a period of 3 years, 705 patients with pneumonia were screened with a Legionella urinary antigen test, and pneumonia was confirmed by culture and serological tests. Twelve cases of legionnaires disease were identified, none of which were hospital acquired, despite the fact that 60% of hospital water samples were contaminated with Legionella pneumophila at a concentration of more than 103 colony-forming units/L. The probable source of infection was identified for only 2 community-acquired cases. The results show that environmental contamination alone is not able to predict the risk of legionnaires disease. If no cases are present, monitoring of hospital water systems is of little significance; clinical surveillance is much more important.
Prevalence of Community-Acquired Methicillin-Resistant Staphylococcus aureus Colonization in a Random Sample of Healthy Individuals
Authors: Rim Jean Y. , Bacon Alfred E.
Published: August 2007

Background.

Concern has recently arisen that the prevalence of methicillin-resistant Staphylococcus aureus (MRSA) colonization among populations at low risk for acquiring this pathogen has been increasing. Although previous studies have reported on the prevalence of MRSA colonization, most of these studies have been performed in healthcare settings, with few studies performed in the community among healthy individuals in nonhealthcare locations.

Objectives.

To determine the prevalence of community-acquired (CA) MRSA colonization in a random sample of healthy individuals in 4 nonhealthcare locations and to compare the genetic similarity between these CA isolates and nosocomial MRSA isolates.

Design.

Prospective, observational study conducted from October 2004 through February 2005.

Setting.

Two colleges, 1 church, and 1 restaurant in Newark and Wilmington, Delaware.

Participants.

A total of 295 healthy volunteers.

Results.

The rate of S. aureus colonization was 26.8%. Of the 79 S. aureus isolates analyzed, 3 (4%) were resistant to methicillin. Ribotyping of the 3 MRSA isolates showed that they were genetically distinct from each other. Each of the 3 CA isolates were genetically indistinguishable from 3 different nondominant clusters of MRSA isolates found in the medical and surgical intensive care units of Christiana Care Health System (Newark) and Wilmington Hospital (Wilmington).

Conclusion.

The overall prevalence of CA-MRSA colonization in a random sample of healthy individuals in 4 nonhealthcare locations in Newark and Wilmington was 1.0%. Despite concerns that the prevalence of MRSA colonization is increasing, it still remains relatively low in our community, perhaps because CA-MRSA colonization tends to occur in clusters.
Measurement of the Impact of Risk Adjustment for Central Line–Days on Interpretation of Central Line–Associated Bloodstream Infection Rates
Authors: Tokars Jerome I. , Klevens R. Monina , Edwards Jonathan R. , Horan Teresa C.
Published: August 2007

Objective.

To describe methods to assess the practical impact of risk adjustment for central line-days on the interpretation of central line–associated bloodstream infection (BSI) rates, because collecting these data is often burdensome.

Methods.

We analyzed data from 247 hospitals that reported to the adult and pediatric intensive care unit component of the National Nosocomial Infections Surveillance System from 1995 through 2003. For each unit each year, we calculated the percentile error as the absolute value of the difference between the percentile based on a risk-adjusted or more-sophisticated measure (eg, the central line–day rate) and the percentile based on a crude or less-sophisticated measure (eg, the patient-day rate). Using rate per central line–day as the “gold standard,” we calculated performance characteristics (eg, sensitivity and predictive values) of rate per patient-day for finding central line–associated BSI rates higher or lower than the mean. Greater impact of risk adjustment is indicated by higher values for percentile error and lower values for performance characteristics.

Results.

The median percentile error was ± 7 (ie, the percentile based on central line-days could be 7% higher or lower than the percentile based on patient-days). This error was less than 10 percentile points for 62% of the unit-years, was between 10 and 19 percentile points for 22% of the unit-years, and was 20 percentile points or more for 15% of the unit-years. Use of the rate based on patient-days had a sensitivity of 76% and a positive predictive value of 61% for detecting a significantly high or low central line–associated BSI rate.

Conclusions.

We found that risk adjustment for central line–days has an important impact on the calculated central line–associated BSI percentile for some units. Similar methods can be used to evaluate the impact of other risk adjustment methods. Our results support current recommendations to use central line–days for surveillance of central line–associated BSI when comparisons are made among facilities.
An evaluation of the dosimetric performance characteristics of N-vinylpyrrolidone-based polymer gels
Authors: Papadakis A E , Maris T G , Zacharopoulou F , Pappas E , Zacharakis G , Damilakis J
Published: August 2007

The aim of this work was to investigate the dosimetric performance properties of theN-vinylpyrrolidone argon (VIPAR) based polymer gel as a dosimetric tool in clinical radiotherapy. VIPAR gels with a larger concentration of gelatin than the standard recipe were manufactured and irradiated up to 68 Gy using a 6 and 18 MV linear accelerator. Using MRI, the R2-dose response was recorded at different imaging sessions within a 34 day time period post-irradiation. The R2-dose response was found to be linear between 5 and 68 Gy. Although dose sensitivity did not show significant variation with time, the measured R2-dose values showed an increasing trend, which was less evident beyond 17 days. At one day post-irradiation, calculated dose standard uncertainties at 20 Gy and 56 Gy were 2.2% and 1.7%, providing a dose resolution of 0.45 Gy and 0.97 Gy, respectively. Although these values fulfilled the 2% limit of ICRU, when gels were imaged at one day post-irradiation, it was shown that the temporal evolution of the R2 values deteriorated the per cent standard uncertainty and the dose resolution by ∼57%, when imaged 17 days post-irradiation. Variation in the coagulation temperature of the gels did not impact the R2-dose sensitivity. This study has shown that the VIPAR gel has the properties of a dosimetric tool required in clinical radiotherapy, especially in applications where a wide dose dynamic range is employed. For results with the lowest per cent uncertainty and the optimum dose resolution, the dosimetry gels used in this work should be MR scanned at one day post-irradiation. Furthermore, a preliminary study on the R2-dose response of a new normoxicN-vinylpyrrolidone-based polymer gel showed that it could potentially replace the traditional VIPAR gel formulation, while preserving the wide dynamic dose response inherent to that monomer.
Intrinsic Dynamic Behavior of Fascin in Filopodia
Authors: Aratyn Yvonne S. , Schaus Thomas E. , Taylor Edwin W. , Borisy Gary G.
Published: August 2007

Recent studies showed that the actin cross-linking protein, fascin, undergoes rapid cycling between filopodial filaments. Here, we used an experimental and computational approach to dissect features of fascin exchange and incorporation in filopodia. Using expression of phosphomimetic fascin mutants, we determined that fascin in the phosphorylated state is primarily freely diffusing, whereas actin bundling in filopodia is accomplished by fascin dephosphorylated at serine 39. Fluorescence recovery after photobleaching analysis revealed that fascin rapidly dissociates from filopodial filaments with a kinetic off-rate of 0.12 s−1and that it undergoes diffusion at moderate rates with a coefficient of 6 μm2s−1. This kinetic off-rate was recapitulated in vitro, indicating that dynamic behavior is intrinsic to the fascin cross-linker. A computational reaction–diffusion model showed that reversible cross-linking is required for the delivery of fascin to growing filopodial tips at sufficient rates. Analysis of fascin bundling indicated that filopodia are semiordered bundles with one bound fascin per 25–60 actin monomers.
Use of the Novel Plk1 Inhibitor ZK-Thiazolidinone to Elucidate Functions of Plk1 in Early and Late Stages of Mitosis
Authors: Santamaria Anna , Neef Rüdiger , Eberspächer Uwe , Eis Knut , Husemann Manfred , Mumberg Dominik , Prechtl Stefan , Schulze Volker , Siemeister Gerhard , Wortmann Lars , Barr Francis A. , Nigg Erich A.
Published: August 2007

Polo-like kinase 1 (Plk1) is a key regulator of mitotic progression and cell division in eukaryotes. It is highly expressed in tumor cells and considered a potential target for cancer therapy. Here, we report the discovery and application of a novel potent small-molecule inhibitor of mammalian Plk1, ZK-Thiazolidinone (TAL). We have extensively characterized TAL in vitro and addressed TAL specificity within cells by studying Plk1 functions in sister chromatid separation, centrosome maturation, and spindle assembly. Moreover, we have used TAL for a detailed analysis of Plk1 in relation to PICH and PRC1, two prominent interaction partners implicated in spindle assembly checkpoint function and cytokinesis, respectively. Specifically, we show that Plk1, when inactivated by TAL, spreads over the arms of chromosomes, resembling the localization of its binding partner PICH, and that both proteins are mutually dependent on each other for correct localization. Finally, we show that Plk1 activity is essential for cleavage furrow formation and ingression, leading to successful cytokinesis.
Mechanism of Reflex Regulation of the Gastroduodenal Function by Acupuncture
Authors: Noguchi Eitaro
Published: August 2007

Many clinical studies focus on the effects of acupuncture on digestive disorders. However, few studies describe the mechanism by which these effects are produced. We present some recent experimental work on the mechanism of acupuncture for reflex regulation of gastroduodenal function in anesthetized rats. In anesthetized rats, it has been proven that acupuncture to the abdomen excites sympathetic nerves via spinal reflexes causing inhibition of motilities while acupuncture of limbs excites vagus nerves via supraspinal reflexes causing an increase in the motilities. It has also been shown that in order to inhibit gastric motilities, acupuncture stimulation of the abdomen must be strong enough to excite group VI fibers of the afferent intercostal nerves. To increase gastric motilities, acupuncture stimulation to hind limbs must be strong enough to excite the high‐threshold group III fibers of tibial nerves. It has also been shown that the neural mechanism of duodenal motility stimulation by acupuncture involves the same body regions and intensity of stimulation as that of gastric motilities. Theories regarding the underlying mechanism have proposed somato‐autonomic reflexes and responses via endogenous opioids, etc., but without definitive conclusions.
Multiple myeloma plasma cells show different chemokine receptor profiles at sites of disease activity
Authors: Trentin Livio , Miorin Marta , Facco Monica , Baesso Ilenia , Carraro Samuela , Cabrelle Anna , Maschio Nilla , Bortoli Michela , Binotto Gianni , Piazza Francesco , Adami Fausto , Zambello Renato , Agostini Carlo , Semenzato Gianpietro
Published: August 2007

Chemokines and their receptors play a pivotal role in the regulation of B‐lymphocyte trafficking. This study was aimed at investigating the pattern of chemokine receptor expression, including CCR1 to CCR3, CCR5 to CCR7, CXCR1 to CXCR5, and the migration ability of multiple myeloma (MM) plasma cells (PC). PC were recovered from the bone marrow (BM) of 29 MM patients, extramedullary sites of 10 patients and the BM of five controls. Flow cytometry analysis showed that the receptors mainly expressed on malignant BM PC were represented by CXCR4 (70% of patients), CCR1 (25%), CCR2 (25%), CCR5 (17%) and CXCR3 (20%), while other receptors were commonly lacking. The analysis performed on extramedullary (peripheral blood and pleural effusion) malignant PC demonstrated that the most represented receptors were CXCR4 (100%), CCR2 (66%) and CXCR1 (60%). The migratory capability of malignant PC at resting conditions identified three groups of patients with different migration (low, intermediate and high). As CXCR4 was the relevant chemokine receptor expressed by MM PC, its ligand CXCL12 induced their migration. These data suggest that malignant PC from MM display different chemokine receptor profiles and that CXCR4 is fully functional and might play a role in the spreading of the disease.
Preferential hypermethylation of the Dickkopf‐1 promoter in core‐binding factor leukaemia
Authors: Suzuki Rikio , Onizuka Makoto , Kojima Minoru , Shimada Masako , Fukagawa Satomi , Tsuboi Kosuke , Kobayashi Hiroyuki , Shintani Ayumi , Ogawa Yoshiaki , Kawada Hiroshi , Hotta Tomomitsu , Ando Kiyoshi
Published: August 2007

The Dickkopf‐1 (DKK1) gene product is an extracellular Wnt inhibitor. Hypermethylation of the DKK1 promoter results in transcriptional silencing and may play an important role in cancer development. Here, we investigated hypermethylation of the DKK1 promoter in patients with acute myeloid leukaemia (AML), especially core‐binding factor (CBF) leukaemia. The methylation status of DKK1 was analysed using methylation‐specific polymerase chain reaction in 47 patients with AML. DKK1 methylation was found in 14 (29·8%) patients, and more frequently in those with CBF leukaemia (6 of 12 patients), than in those with acute promyelocytic leukaemia (APL) (0 of 6 patients) (P = 0·03). In contrast, Wnt inhibitory factor‐1 methylation was found in APL (4 of 6 patients) but not in CBF leukaemia (0 of 12 patients) (P = 0·001). Multivariate analyses suggested that DKK1 methylation was a risk factor for poorer overall survival. Sequential analysis using four paired samples obtained at diagnosis and relapse suggested that DKK1 methylation was involved in the progression of leukaemia. Therefore, DKK1 methylation may be involved in leukaemogenesis, especially in CBF leukaemia, and may be a useful prognostic marker in AML.
The risk associated with indwelling catheters in children with haemophilia
Authors: Ljung Rolf
Published: August 2007

Infections are the most frequent complications associated with the use of central venous lines (CVLs) in children with haemophilia. Several retrospective studies that include data from a substantial number of patients have reported approximately 0·2–0·3 infections per 1000 catheter‐days (mainly Port‐A‐Cath). Some studies have shown a much higher frequency of infections, 1–2/1000 catheter‐days. The most plausible explanations, for the difference seen in frequency of infections with Port‐A‐Caths, are probably related to the protocol used for the device care and the quality of education and the compliance of the users, whether these are parents or health‐care professionals. The figures are low for clinically apparent thrombosis in the larger series on record, but routine venograms were not performed in most of these series. In studies, where this has been performed, a high frequency of abnormalities (>50%) on venograms have been seen in some series but not in others. Despite obvious potential risks with CVLs, they are useful in many cases and facilitate the treatment of a serious disorder. With careful guidelines and surveillance protocols, the risk of complications should be reduced in the future.
Effect on upland beef production of incorporating winter feeding of red clover silage or summer grazing of Molinia‐dominated semi‐natural pastures
Authors: Fraser M. D. , Davies D. A. , Wright I. A. , Vale J. E. , Nute G. R. , Hallett K. G. , Richardson R. I.
Published: August 2007

Management systems for finishing beef cattle, designed to meet environmental goals in the Less Favoured Areas (LFAs) of the UK, often rely on the integration of grazing of semi‐natural pastures with sown permanent pasture. In this experiment, three management options were compared: (i) permanent pasture for grazing and silage production (treatment PP), (ii) permanent pasture for grazing and silage and grazing of Molinia‐dominant semi‐natural pasture in summer from June to August inclusively (treatment PP + SNP) and (iii) permanent pasture for grazing and silage and red clover (RC) silage for 0·25 of the silage requirement in winter (treatment PP + RC). The performance of spring‐born Welsh Black steers was measured from turnout in spring 2002 until finishing in summer 2003. During summer 2002, the liveweight gain of steers grazing the semi‐natural pasture was significantly lower than that of steers grazing the permanent pasture. There was a trend for the liveweight gains of the steers on the PP + SNP treatment to be higher from housing in autumn 2002, and live weights on all treatments were similar at the start of the red clover‐feeding phase. Steers offered red clover silage had a significantly higher liveweight gains than those offered grass silage, but there was only a trend for a higher live weight at the end of the winter‐feeding period. During summer 2003, liveweight gains were again higher on the permanent pasture. Finishing system significantly affected the fatty‐acid profile of the meat produced, but there was no difference in the colour of meat in relation to shelf‐life. Lipid oxidation was less for the meat from steers on the PP + SNP treatment than on the PP treatment, which, in turn, was less than for meat from the steers on the PP + RC treatment, and was in inverse proportion to the vitamin E concentration in the loin muscle. There were no significant differences in sensory panel scores for texture, juiciness or flavour of the meat.
The effects of offering a range of forage and concentrate supplements on milk production and dry matter intake of grazing dairy cows
Authors: Morrison S. J. , Patterson D. C.
Published: August 2007

An experiment was undertaken to examine the effect of supplement type on herbage intake, total dry matter (DM) intake, animal performance and nitrogen utilization with grazing dairy cows. Twenty‐four spring‐calving dairy cows were allocated to one of six treatments in a partially balanced changeover design with five periods of four weeks. The six treatments were no supplement (NONE), or supplementation with either grass silage (GS), whole‐crop wheat silage (WS), maize silage (MS), rapidly degradable concentrate (RC) or slowly degradable concentrate (SC). Cows were rotationally grazed with a mean herbage allowance of 20·5 kg DM per cow per day, measured above 4 cm. Forage supplements were offered for approximately 2 h immediately after each morning milking, with cows on NONE, RC and SC treatments returning to the grazing paddock immediately after milking. Cows on treatment MS had a significantly higher supplement DM intake than the other treatments but a significantly lower grass DM intake than the other treatments, resulting in no significant difference in total DM intake when compared with cows on treatments WS, RC and SC. Concentrate type had no significant effect on herbage intake, milk yield, milk composition or yield of milk components. The yield of milk fat and milk protein was significantly higher on treatments MS, RC and SC compared with treatments NONE, GS and WS. The results indicate that despite a relatively high substitution rate, maize silage can be a useful supplement for the grazing dairy cow.
Effects of ruminal fill on short‐term herbage intake rate and grazing dynamics of beef heifers
Authors: Gregorini P. , Gunter S. A. , Masino C. A. , Beck P. A.
Published: August 2007

The impact of manipulating ruminal fill (RF) on intake rate of herbage and grazing dynamics was measured with three rumen‐cannulated beef heifers grazing Bermudagrass pastures individually. The treatments compared were removal of proportions of rumen contents of 0 (treatment RF0), 0·33 (treatment RF33), 0·66 (treatment RF66) and 1·00 (treatment RF100). Treatments were randomly applied in a 3 × 4 Youden‐square design. The rumens were emptied before and after planned grazing sessions (30 min) to set up the treatments, and to estimate intake rate and bite mass, respectively. Measurements were made of bite rate, bites per feeding station, feeding stations per minute, intake per feeding station, time per feeding station, eating and searching step rates and times. Apparent bite area and area grazed per feeding station were calculated. Ruminal fill affected short‐term intake rate and changed grazing dynamics. As RF increased, step rates, searching times, bite mass, apparent bite area, bites per feeding station, area grazed per feeding station, time per feeding station and intake per feeding station decreased (P < 0·01) while step times, eating step rates and bite depth increased (P < 0·01). The results of the present study indicate that RF is an important factor governing the intake characteristics and behaviour of grazing beef heifers.
Fungal alkaloids in populations of endophyte‐infected Festuca rubra subsp. pruinosa
Authors: Vázquez‐de‐Aldana B. R. , Zabalgogeazcoa I. , García‐Ciudad A. , García‐Criado B.
Published: August 2007

Festuca rubra subsp. pruinosa is a grass that grows on coastal cliffs along the Atlantic coast of Europe. Asymptomatic plants of this species are systemically infected by the fungal endophyte Epichloë festucae. It is not known whether the alkaloids, ergovaline and peramine, are produced by the endophyte in F. rubra subsp. pruinosa. Plants from four populations were collected from the northern coast of Galicia (Spain) and examined for the presence of fungal endophytes. Ergovaline and peramine concentrations were analysed over two consecutive years, at two plant growth stages, and in different types of plant tissues. Infected plants of F. rubra subsp. pruinosa contained ergovaline but not peramine. Ergovaline was detected in 0·80 of the plants, with concentrations ranging from 0·05 to 1·9 μg g−1 dry matter. The differences in ergovaline concentration between different types of plant tissues (vegetative and reproductive), plant populations and sampling dates were not statistically significant.
Effects of two mixtures of perennial ryegrass cultivars with contrasting heading dates, and differing in spring‐grazing frequency and silage harvest date, on characteristics of silage from first‐cut swards
Authors: Humphreys J. , O’Kiely P.
Published: August 2007

This experiment quantified the effects of: (i) heading date of perennial ryegrass, (ii) grazing frequency in spring and (iii) date of silage harvest, on the ensilability of herbages harvested for silage, and on the conservation and estimated nutritive value of the resultant silages. Replicated field plots with two perennial ryegrass mixtures (intermediate‐ and late‐heading cultivars) were subjected to three spring‐grazing regimes (no grazing, grazing in late March and grazing in both late March and late April) and were harvested on four first‐cut harvest dates between 20 May and 21 June. Herbage from each of the four replicates of these 24 treatments was precision‐chopped and ensiled unwilted and with no additive in laboratory silos. Herbage from the sward with the intermediate‐heading cultivar had a higher (P < 0·001) dry‐matter (DM) content and buffering capacity than that from the late‐heading cultivar, whereas water‐soluble carbohydrate concentrations increased (P < 0·001) with more frequent grazing in spring. Later harvesting enhanced herbage ensilability through an increased (P < 0·001) DM content and reduced (P < 0·001) buffering capacity and pH. Fermentation profiles of the silage were not markedly influenced by the cultivar mixture used but grazing in both late March and late April resulted in a more extensive fermentation with the acids produced increasingly dominated by lactic acid. The concentrations of acetic acid, and to a lesser extent, ethanol declined as silage harvest date was delayed. Overall, the relative effects of grass cultivar mixture were smaller than those of spring‐grazing treatment or silage‐harvesting date although on any given harvest date the herbage from the intermediate‐heading cultivar mixture was easier to preserve as silage than herbage from the late‐heading cultivar mixture. Delaying the harvesting of the late‐heading swards by 8 d removed the differences related to growth stage in buffering capacity, pH and DM content.