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At least 379 records · Page 21Linked to original sources

PubMed2003

Sacral stress fracture in a female field hockey player.

We report a collegiate field hockey player who sustained a sacral fatigue-type stress fracture that manifested as persistent low back and leg pain. The diagnosis of sacral stress fracture was suggested by history and physical examination and confirmed by magnetic resonance imaging. Our patient experienced complete resolution of symptoms after a 3-mo interval of activity restriction. This article describes the first reported case of a sacral stress fracture in a field hockey player.

Adult↗

PubMed2004

Observation of force-detected nuclear magnetic resonance in a homogeneous field.

We report the experimental realization of BOOMERANG (better observation of magnetization, enhanced resolution, and no gradient), a sensitive and general method of magnetic resonance. The prototype millimeter-scale NMR spectrometer shows signal and noise levels in agreement with the design principles. We present 1H and 19F NMR in both solid and liquid samples, including time-domain Fourier transform NMR spectroscopy, multiple-pulse echoes, and heteronuclear J spectroscopy. By measuring a 1H-19F J coupling, this last experiment accomplishes chemically specific spectroscopy with force-detected NMR. In BOOMERANG, an assembly of permanent magnets provides a homogeneous field throughout the sample, while a harmonically suspended part of the assembly, a detector, is mechanically driven by spin-dependent forces. By placing the sample in a homogeneous field, signal dephasing by diffusion in a field gradient is made negligible, enabling application to liquids, in contrast to other force-detection methods. The design appears readily scalable to microm-scale samples where it should have sensitivity advantages over inductive detection with microcoils and where it holds great promise for application of magnetic resonance in biology, chemistry, physics, and surface science. We briefly discuss extensions of the BOOMERANG method to the microm and nm scales.

Data Interpretation, Statistical↗

PubMed2005

Theoretical evaluation of voltage inducement on internal membranes of biological cells exposed to electric fields.

Several reports have recently been published on effects of very short and intense electric pulses on cellular organelles; in a number of cases, the cell plasma membrane appeared to be affected less than certain organelle membranes, whereas with longer and less intense pulses the opposite is the case. The effects are the consequence of the voltages induced on the membranes, and in this article we investigate the conditions under which the induced voltage on an organelle membrane could exceed its counterpart on the cell membrane. This would provide a possible explanation of the observed effects of very short pulses. Frequency-domain analysis yields an insight into the dependence of the voltage inducement on the electric and geometric parameters characterizing the cell and its vicinity. We show that at sufficiently high field frequencies, for a range of parameter values the voltage induced on the organelle membrane can indeed exceed the voltage induced on the cell membrane. Particularly, this can occur if the organelle interior is electrically more conductive than the cytosol, or if the organelle membrane has a lower dielectric permittivity than the cell membrane, and we discuss the plausibility of these conditions. Time-domain analysis is then used to determine the courses of the voltage induced on the membranes by pulses with risetimes and durations in the nanosecond range. The particularly high resting voltage in mitochondria, to which the induced voltage superimposes, could contribute to the explanation why these organelles are the primary target of many observed effects.

Animals↗

PubMed2004

Monte Carlo calculations of output factors for clinically shaped electron fields.

We report on the use of the EGS4/BEAM Monte Carlo technique to predict the output factors for clinically relevant, irregularly shaped inserts as they intercept a linear accelerator's electron beams. The output factor for a particular combination--energy, cone, insert, and source-to-surface distance (SSD)--is defined in accordance with AAPM TG-25 as the product of cone correction factor and insert correction factor, evaluated at the depth of maximum dose. Since cone correction factors are easily obtained, we focus our investigation on the insert correction factors (ICFs). An analysis of the inserts used in routine clinical practice resulted in the identification of a set of seven "idealized" shapes characterized by specific parameters. The ICFs for these shapes were calculated using a Monte Carlo method (EGS4/BEAM) and measured for a subset of them using an ion chamber and well-established measurement methods. Analytical models were developed to predict the Monte Carlo-calculated ICF values for various electron energies, cone sizes, shapes, and SSDs. The goodness-of-fit between predicted and Monte Carlo-calculated ICF values was tested using the Kolmogorov-Smirnoff statistical test. Results show that Monte Carlo-calculated ICFs match the measured values within 2.0% for most of the shapes considered, except for few highly elongated fields, where deviations up to 4.0% were recorded. Predicted values based on analytical modeling agree with measured ICF values within 2% to 3% for all configurations. We conclude that the predicted ICF values based on modeling of Monte Carlo-calculated values could be introduced in clinical use.

Body Burden↗

PubMed1990

A system for the reconstruction and analysis of dendritic fields.

We report here the development of a fast and 'user friendly' Semiautomatic Neuron Reconstruction and Analysis System (SANRAS) based on a Zeiss Universal microscope, Kontron Microscope Control Processor (MCP), and Apple Macintosh SE microcomputer. Four programs for digitisation and analysis have been written; STAGE, CONVERTZ, RECON and SHOLL. Cells are digitised by superimposing ocular crosshairs on a dendrite and tracing directly, the stage position in x, y, and z co-ordinates being recorded by the computer at points indicated by a keypress. Cells can be digitised from serial thick sections and dendritic reconstructions can be visualised on screen, rotated and viewed from any angle. Output is given either to a Hewlett Packard colour plotter or to a laser printer, in graphical form, and as a summary of various metrical and topological parameters. Radial Scholl diagrams of dendritic trees may also be produced. Dendritic branching patterns of Golgi-impregnated neurons of the left and right intermediate medial hyperstriatum ventrale of the chick are described.

Animals↗

PubMed2006

Stability and decolourization ability of Trametes villosa laccase in liquid ultrasonic fields.

We report in this study that the sonication of laccase from Trametes villosa and bovine serum albumin promotes the formation of protein aggregates with high molecular weight. The formation of aggregates leads to the deactivation of the enzyme, fact that was confirmed by the analysis of the enzyme stability (half-life time) upon ultrasound treatment. This inactivation was mainly caused by the radicals formed by the cavitation phenomenon. It was verified that the addition of polyvinyl alcohol to laccase had a protecting effect against enzyme inactivation. The performance of laccase in the decolourization of indigo carmine was studied. It was observed that the best results were attained when the dye solution was treated with ultrasound and enzyme stabilized with polyvinyl alcohol, where more than 65% of decolourization was achieved. This value is remarkably higher than that attained for the enzyme alone, which was only able to decolourize 20% of the dye solution within 1h of treatment. These results have important implications for the exploitation of sonication in textile industry, where the pollution caused by the release of dyes into effluents is one of the major concerns.

Basidiomycota↗

PubMed2006

Cardiac biomarkers: a contemporary status report.

The field of cardiac biomarkers has grown by leaps and bounds in the past two decades. In this review we try to summarize the explosion of emerging knowledge and address the roles of some of the biomarkers that have either proven or potential utility. We detail some of the markers of ischemia, hemodynamic markers of heart failure, inflammatory markers, and the novel and innovative approach of combining these for a multimarker strategy. At the end of this review we highlight some of the biomarker-guided approaches and strategies that might lead to better and more-effective care of patients.

Biomarkers↗

PubMed1986

Providing resistive breathing exercise to the inspiratory muscles using the PFLEX device. Suggestion from the field.

This report describes a 6-step process for prescribing resistive inspiratory exercise using the PFLEX device, which is an inexpensive and effective method of enhancing the performance of the vital muscles of respiration. Until further clinical validation of minimal threshold guidelines for prescribing PEPs is achieved, the clinical judgment of the physical therapist remains the most important element in the prescription process.

Aged↗

PubMed2004

Many-electron dynamics of a Xe atom in strong and superstrong laser fields.

We report on detailed investigations of ionization dynamics of a Xe atom exposed to intense 800-nm pulses of 20-fs duration in the extensive intensity range from 10(13)-10(18) W/cm(2). Ion yields of Xe+-Xe20+ were observed as a function of laser intensity and compared with the results from a single active electron based Ammosov-Delone-Krainov model. Unexpected ionization probabilities for lower charge states and no interplay between the inner and outer shells by screening are inferred. Suppression of nonsequential ionization towards higher intensity and few optical cycle regimes is also proved.

Journal Article↗

PubMed2004

Evidence for current-flow anomalies in the irradiated 2D electron system at small magnetic fields.

We report experimental transport results in 2D electron systems exposed to dipole radiation up to 20 GHz. Magnetoresistance oscillations occur as seen with higher frequency radiation; however, minima here can be seen to extend to negative biases, and zeros are not observed persistently around sample perimeters. Under radiation, voltages are generated from internal to external contacts in the absence of applied driving currents. These findings may be consistent with theoretical pictures of current instabilities due to local negative resistivities.

Journal Article↗

PubMed2006

Selective ionization of oriented nonpolar molecules with asymmetric structure by phase-controlled two-color laser fields.

We report on the selective ionization of oriented nonpolar molecules with asymmetric structure by using phase-controlled two-color omega + 2omega laser pulses with an intensity of 1.0 x 10(13) W/cm(2) (tunneling ionization regime) and a pulse duration of 130 fs. The orientation of 1-bromo-2-chloroethane was monitored by the directional asymmetries of the forward-backward emission in dissociative ionization. The observed direction of orientation clearly confirms that molecular orientation is induced not by dynamic orientation but by selective ionization of oriented molecules, which reflects the structure of the highest occupied molecular orbital. This method can be applied for the vast majority of molecules.

Journal Article↗

PubMedDate not supplied

Improving pediatric chemotherapy safety through voluntary incident reporting: lessons from the field.

BACKGROUND: A multidisciplinary team within Vanderbilt Children's Hospital (VCH) designed, developed, and implemented a pediatric chemotherapy incident reporting and improvement system (CIRIS) for pediatric oncology nurse and pharmacists. The aim of this collaboration was to improve pediatric chemotherapy by translating recommendations made by the Institute of Medicine into an operational safety improvement system that is embedded into daily care processes. METHODS: CIRIS improves chemotherapy safety by linking two distinct components: (a) a technical component that uses desktop, laptop, and portable wireless handheld computers to interface the Web-based software application for point-of-care incident reporting and on-demand retrieval of patient support information, and (b) a human component that performs process analysis, data reporting, and clinical improvement. This integrated system facilitates and supports a blame-free culture for reporting of near misses and preventable adverse drug events. RESULTS: Between February 8, 2002, and March 9, 2003, pediatric oncology nurses and chemotherapy pharmacists electronically reported 97 chemotherapy-related incidents associated with 96 unique patients. Ordering errors were the most commonly reported incidents. CIRIS improved reporting performance demonstrated using the conventional paper-based reporting system.

Antineoplastic Agents↗

PubMed2003

Transient optical elements: application to near-field microscopy.

We report methods of near-field infrared microscopy with transient optically induced probes. The first technique - a transient aperture (TA) - uses photoinduced reflectivity in semiconductors to generate a relatively large transient mirror (TM) with a small aperture at its centre. We report the optical properties of the TM and TA and experiments performed on near-field imaging with the TA. The second technique is based on solid immersion microscopy, in which high resolution is achieved when light is focused inside a solid with a high refractive index. By creating a transient Fresnel lens on the surface of a semiconductor wafer via photoinduction, we were able to form a solid immersion lens (SIL) for use as a near-field probe. The use of transient probes eliminates the need for mechanical scanning of the lens or sample, and thus provides a much faster scanning rate and the possibility to work with soft and liquid objects.

Journal Article↗

PubMed1986

[Oral vaccination of foxes against rabies in free game areas--a field trial].

It is reported about a field trial of oral vaccination of foxes against rabies, started in some Bavarian districts. The planning stage, the preparation of baits and their distribution, and the subsequent investigations to evaluate the field trial are outlined. The vaccine will be produced by the Federal Research Institute for Animal Diseases at Tübingen. 110,000 vaccine baits were laid out in 4 vaccination campaigns within 2 years. In no instance vaccine virus could be reisolated from animals collected in the vaccination zone. About 50% of the foxes were successfully immunized.

Administration, Oral↗

PubMed2006

Assessing risk of resistance to aerial applications of methyl-parathion in western corn rootworm (Coleoptera: Chrysomelidae).

We validated a stochastic model of the evolution of resistance to adulticidal sprays of methyl-parathion in western corn rootworm, Diabrotica virgifera virgifera LeConte, populations in Nebraska. The population dynamics predicted by the model resembled that reported for field populations, and time until control failures occurred closely matched reports by commercial crop consultants. We incorporated uncertainty about the values used for 18 model parameters by replacing default values with random draws taken from a normal distribution. One parameter, the initial resistance allele frequency, was no longer measurable because of the evolution of resistance. We therefore proposed five candidate initial allele frequencies and developed probability distributions for the time to resistance for each by running 1000 simulations with parameters randomly varied. These distributions included variation because of stochastic effects as well as parameter uncertainty. We used Bayesian inference to estimate the candidate frequency most likely, given reported times to field control failures. The initial allele frequency of 10(-4) was most likely (29%), 10(-3) was less likely (28%), whereas 10(-6) was relatively unlikely (5%). Results from sensitivity analysis depended upon how evolution of resistance was measured. When resistance was examined as a genetic phenomenon, the rate of increase of the resistance allele depended almost entirely on genetic factors (LC50 values), the characteristics of the pesticide (residual activity), and the variance associated with emergence of adults. When resistance was measured as failure of methyl-parathion to reduce populations below threshold levels (0.5 gravid females per plant), parameters that contributed to population growth rate (mortality and fecundity) were also important. These data suggest two important phases in resistance evolution in corn rootworms: a genetic phase associated with negative growth rates and rapid changes in resistance allele frequencies and a rebound phase associated with positive growth rates and near fixation of the resistance allele.

Animals↗

PubMed1983

Dapsone compliance in an urban field project.

Available reports both from rural and urban leprosy centres prove beyond any doubt that dapsone is not being consumed regularly by all those who show regular clinic attendance. No reports are available from urban field projects where SET programme is being operated. In this study surprise urine samples of 294 patients of all types (smear positive 53%) mainly on dapsone monotherapy attending (1) leprosy treatment centres in slum clinics situated in the field areas adopted for SET work by Bombay Leprosy Project and (2) general hospital clinics situated predominantly outside the project area were analysed for dapsone/creatinine ratio to judge the extent of drug compliance. 201 out of 294 (68%) were regular and 82 out of 294 (28%) were irregular in consuming DDS as judged by urine examination. 67% of smear positive cases were regular. No difference was found in regularity between patients living within the project area (intensive follow up is done in this group to remind about treatment) and outside project area patients (no reminder followup is done). Similarly no difference was observed in regularity amongst the patients attending slum clinics and general hospital clinics. It could be stated that facilities for treatment offered at general hospitals or dispensaries and encouraging voluntary reporting could be quite fruitful and economical for obtaining better drug compliance in urban areas.

Dapsone↗

PubMed2004

Identification of a resonant imaging process in apertureless near-field microscopy.

We report on apertureless near-field microscopy in the far infrared. We identify a configurational resonance of the scanning tip-surface system to be the dominating mechanism that forms the image. Experimental data such as the high imaging contrast and its spectral properties can be well explained and make the framework of a mesoscopic resonance an alternative to conventional scattering models that are used to interpret near-field data. Our findings are plausibly not restricted to the far infrared and may impact on near-field spectroscopy in general.

Journal Article↗

PubMedDate not supplied

Melatonin suppression by static and extremely low frequency electromagnetic fields: relationship to the reported increased incidence of cancer.

An increased cancer incidence has been reported in individuals living and/or working in an environment in which they are exposed to higher than normal artificial electromagnetic fields. One of the most uniform changes associated with the exposure of animals to either pulsed static geomagnetic fields or to sinusoidal extremely low frequency magnetic fields has been a reduction in high night-time levels of melatonin. Melatonin is a hormone produced especially at night in the pineal gland, a pea-sized organ near the center of the human brain. The high nocturnal production of melatonin leads to elevated blood melatonin levels at night as well. The exposure of humans or animals to light (visible electromagnetic radiation) at night rapidly depresses pineal melatonin production and blood melatonin levels. Likewise, the exposure of animals to various pulsed static and extremely low frequency magnetic fields also reduces melatonin levels. Melatonin is a potent oncostatic agent and it prevents both the initiation and promotion of cancer. Reduction of melatonin, at night, by any means, increases cells' vulnerability to alteration by carcinogenic agents. Thus, if in fact artificial electromagnetic field exposure increases the incidence of cancer in humans, a plausible mechanism could involve a reduction in melatonin which is the consequence of such exposures.

Animals↗