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PubMed1982

[High resolution computerized tomography for the determination of fractures of the base of the skull, particularly the petrous bone].

Using high resolution CT, the high spatial resolution is comparable to conventional pluridirectional tomography. The small pixel size allows visualization of minute fractures of the skull base or the petrous bone. High resolution CT clearly demonstrated 32 fractures of the skull base, 14 of them passing through the petrous pyramids. The CT examination with the high resolution mode can be performed at the same time as the regular CT examination of the brain. This procedure is less time consuming and safer for the traumatized patient than the separate examination of the brain and the skull base with regular CT and conventional tomography respectively. As with conventional radiologic methods, the fractures are best demonstrated if they are oriented at right angles to the scanning plane. Fractures parallel to the scanning plane be missed. Therefore, additional direct coronal scans may be necessary for the accurate demonstration of fractures of the skull base.

Adult↗

PubMed2005

Concurrent dual-resolution Monte Carlo simulation of liquid methane.

We conduct molecular simulations of liquid methane in a system where molecular resolution fluctuates between atomically explicit and spherically symmetric united atoms. An appropriate dual-resolution canonical ensemble is constructed using (a) effective united atom pair potentials and (b) resolution-control potentials that confine explicit and united atoms chiefly to different slabs in the simulation domain. A Monte Carlo simulation is developed to sample this ensemble. We show that compatibility of the united-atom potentials with the explicit potentials in a concurrent simulation can be tuned by adjusting the width of the interface between the two resolution regions and by direct modification of the united-atom pair potentials. Our results lay the groundwork for treatment of larger atomically specific molecules with similar concurrent multiresolution techniques.

Journal Article↗

PubMed2006

High resolution dissociative electron attachment to gas phase adenine.

The dissociative electron attachment to the gas phase nucleobase adenine is studied using two different experiments. A double focusing sector field mass spectrometer is utilized for measurements requiring high mass resolution, high sensitivity, and relative ion yields for all the fragment anions and a hemispherical electron monochromator instrument for high electron energy resolution. The negative ion mass spectra are discussed at two different electron energies of 2 and 6 eV. In contrast to previous gas phase studies a number of new negative ions are discovered in the mass spectra. The ion efficiency curves for the negative ions of adenine are measured for the electron energy range from about 0 to 15 eV with an electron energy resolution of about 100 meV. The total anion yield derived via the summation of all measured fragment anions is compared with the total cross section for negative ion formation measured recently without mass spectrometry. For adenine the shape of the two cross section curves agrees well, taking into account the different electron energy resolutions; however, for thymine some peculiar differences are observed.

Adenine↗

PubMed2002

High-resolution chromoendoscopy for classifying colonic polyps: a multicenter study.

BACKGROUND: Chromoendoscopy may reliably separate adenomatous from nonadenomatous polyps. The aim of this multicenter trial was to determine the accuracy of high-resolution chromoendoscopy for the determination of colonic polyp histology. METHODS: This multicenter trial included 4 academic centers and a primary care practice. In 299 patients referred for routine colonoscopy or sigmoidoscopy, 520 polyps 10 mm in size were sprayed with indigo carmine dye. Using a high-resolution endoscope, the endoscopist predicted the histology of each polyp based on its surface characteristics. Hyperplastic polyps had a "pitted" surface pattern of orderly arranged "dots" that resembled surrounding normal mucosa. Adenomatous polyps had at least one surface "groove" or "sulcus." Each polyp was subsequently resected for histopathologic evaluation. RESULTS: The resected polyps were comprised by 193 adenomas (37%), 225 hyperplastic polyps (43%), and 102 "other" types (20%). Forty polyps (7.7%) could not be classified by high resolution chromoendoscopy with indigo carmine dye. For the remaining polyps, the sensitivity, specificity, and negative predictive value of indigo carmine dye staining for adenomatous polyps were, respectively, 82%, 82%, and 88%. The results were consistent among the academic centers and the primary care practice. CONCLUSIONS: High-resolution chromoendoscopy with indigo carmine dye demonstrates morphologic detail of diminutive colorectal polyps that can reliably be used to separate adenomatous from nonadenomatous polyps.

Adenoma↗

PubMed2003

Endoscopically inserted endoluminal receiver coil for high-resolution magnetic resonance imaging of the pancreas: Initial results in an animal model.

BACKGROUND: This study assessed the feasibility of high-resolution magnetic resonance imaging of the pancreas by means of an endoscopically inserted endoluminal magnetic resonance receiver coil. METHOD: A 0.032-inch diameter internal magnetic resonance imaging receiver coil was endoscopically inserted into the pancreatic duct in 4 pigs through the accessory channel of a standard duodenoscope to obtain high-resolution magnetic resonance images by using T1- and T2-weighted sequences. RESULTS: The pig anatomy precluded the usual transoral approach; however, transgastric access allowed endoscopic transpapillary insertion of a receiver coil into the pancreatic duct in all animals without the need for sphincterotomy. The small swine pancreas could then be visualized by magnetic resonance imaging with a 0.3 x 0.3-mm in-plane resolution. CONCLUSION: High-resolution pancreas magnetic resonance imaging is feasible by using an endoscopically inserted endoluminal receiver coil. The smaller stomach and larger pancreatic duct diameter in humans will facilitate clinical application of the imaging procedure.

Animals↗

PubMed2000

Nonhomogeneous resolution of images of natural scenes.

The aim of this research is to model and simulate the loss of visual resolution as a function of retinal eccentricity in the perception of natural scenes. The model of visual resolution is based on a space-variant low-pass filter, having a variable convolution kernel according to retinal eccentricity. The parameters of the model are computed from psychophysical measures of visual acuity as a function of retinal eccentricity. The implementation of the model allowed us to generate images of scenes with nonhomogeneous space-variant resolution, simulating the filtering executed by the eye. These scenes are used to test and optimise the model by means of experiments in static vision (through tachistoscopic presentations) and in dynamic vision where the resolution of the scene is computed, in real-time, as a function of the location of gaze.

Contrast Sensitivity↗

PubMed2005

Single molecule high-resolution colocalization of Cy3 and Cy5 attached to macromolecules measures intramolecular distances through time.

Here we present a technique called single-molecule high-resolution colocalization (SHREC) of fluorescent dyes that allows the measurement of interfluorophore distances in macromolecules and macromolecular complexes with better than 10-nm resolution. By using two chromatically differing fluorescent molecules as probes, we are able to circumvent the Rayleigh criterion and measure distances much smaller than 250 nm. The probes are imaged separately and localized individually with high precision. The registration between the two imaging channels is measured by using fiduciary markers, and the centers of the two probes are mapped onto the same space. Multiple measurements can be made before the fluorophores photobleach, allowing intramolecular and intermolecular distances to be tracked through time. This technique's lower resolution limit lies at the upper resolution limit of single molecule FRET (smFRET) microscopy. The instrumentation and fluorophores used for SHREC can also be used for smFRET, allowing the two types of measurements to be made interchangeably, covering a wide range of interfluorophore distances. A dual-labeled duplex DNA molecule (30 bp) was used as a 10-nm molecular ruler to confirm the validity of the method. We also used SHREC to study the motion of myosin V. We directly observed myosin V's alternating heads while it walked hand-over-hand along an actin filament.

Animals↗

PubMed2003

Nanodissection and high-resolution imaging of the Rhodopseudomonas viridis photosynthetic core complex in native membranes by AFM. Atomic force microscopy.

In photosynthesis, highly organized multiprotein assemblies convert sunlight into biochemical energy with high efficiency. A challenge in structural biology is to analyze such supramolecular complexes in native membranes. Atomic force microscopy (AFM) with high lateral resolution, high signal-to-noise ratio, and the possibility to nanodissect biological samples is a unique tool to investigate multiprotein complexes at molecular resolution in situ. Here we present high-resolution AFM of the photosynthetic core complex in native Rhodopseudomonas viridis membranes. Topographs at 10-A lateral and approximately 1-A vertical resolution reveal a single reaction center (RC) surrounded by a closed ellipsoid of 16 light-harvesting (LH1) subunits. Nanodissection of the tetraheme cytochrome (4Hcyt) subunit from the RC allows demonstration that the L and M subunits exhibit an asymmetric topography intimately associated to the LH1 subunits located at the short ellipsis axis. This architecture implies a distance distribution between the antenna and the RC compared with a centered location of the RC within a circular LH1, which may influence the energy transfer within the core complex. The LH1 subunits rearrange into a circle after removal of the RC from the core complex.

Image Processing, Computer-Assisted↗

PubMed1982

High-resolution solid-state NMR of quadrupolar nuclei.

We report the observation of high-resolution solid-state NMR spectra of (23)Na (I = [unk]), (27)Al (I = [unk]) and (51)V (I = [unk]) in various inorganic systems. We show that, contrary to popular belief, relatively high-resolution ( approximately 10 ppm linewidth) spectra may be obtained from quadrupolar systems, in which electric quadrupole coupling constants (e(2)qQ/h) are in the range approximately 1-5 MHz, by means of observation of the ((1/2), -(1/2)) spin transition. The ((1/2), -(1/2)) transition for all nonintegral spin quadrupolar nuclei (I = [unk], [unk], [unk], or [unk]) is only normally broadened by dipolar, chemical shift (or Knight shift) anisotropy or second-order quadrupolar effects, all of which are to a greater or lesser extent averaged under fast magic-angle sample rotation. In the case of (23)Na and (27)Al, high-resolution spectra of (23)NaNO(3) (e(2)qQ/h approximately 300 kHz) and alpha-(27)Al(2)O(3) (e(2)qQ/h approximately 2-3 MHz) are presented; in the case of (51)V(2)O(5) (e(2)qQ/h approximately 800 kHz), rotational echo decays are observed due to the presence of a approximately 10(3)-ppm chemical shift anisotropy. The observation of high-resolution solid-state spectra of systems having spins I = [unk], [unk], and [unk] in asymmetric environments opens up the possibility of examining about two out of three nuclei by solid-state NMR that were previously thought of as "inaccessible" due to the presence of large (a few megahertz) quadrupole coupling constants. Preliminary results for an I = [unk] system, (93)Nb, having e(2)qQ/h approximately 19.5 MHz, are also reported.

Journal Article↗

PubMed1998

Echo-delay resolution in sonar images of the big brown bat, Eptesicus fuscus.

Echolocating big brown bats (Eptesicus fuscus) broadcast ultrasonic frequency-modulated (FM) biosonar sounds (20-100 kHz frequencies; 10-50 microseconds periods) and perceive target range from echo delay. Knowing the acuity for delay resolution is essential to understand how bats process echoes because they perceive target shape and texture from the delay separation of multiple reflections. Bats can separately perceive the delays of two concurrent electronically generated echoes arriving as little as 2 microseconds apart, thus resolving reflecting points as close together as 0.3 mm in range (two-point threshold). This two-point resolution is roughly five times smaller than the shortest periods in the bat's sounds. Because the bat's broadcasts are 2,000-4,500 microseconds long, the echoes themselves overlap and interfere with each other, to merge together into a single sound whose spectrum is shaped by their mutual interference depending on the size of the time separation. To separately perceive the delays of overlapping echoes, the bat has to recover information about their very small delay separation that was transferred into the spectrum when the two echoes interfered with each other, thus explicitly reconstructing the range profile of targets from the echo spectrum. However, the bat's 2-microseconds resolution limit is so short that the available spectral cues are extremely limited. Resolution of delay seems overly sharp just for interception of flying insects, which suggests that the bat's biosonar images are of higher quality to suit a wider variety of orientation tasks, and that biosonar echo processing is correspondingly more sophisticated than has been suspected.

Animals↗

PubMed1999

A systematic study of low-resolution recognition in protein--protein complexes.

A comprehensive nonredundant database of 475 cocrystallized protein-protein complexes was used to study low-resolution recognition, which was reported in earlier docking experiments with a small number of proteins. The docking program GRAMM was used to delete the atom-size structural details and systematically dock the resulting molecular images. The results reveal the existence of the low-resolution recognition in 52% of all complexes in the database and in 76% of the 113 complexes with an interface area >4,000 A(2). Limitations of the docking and analysis tools used in this study suggest that the actual number of complexes with the low-resolution recognition is higher. However, the results already prove the existence of the low-resolution recognition on a broad scale.

Algorithms↗

PubMed2004

The atomic resolution crystal structure of atratoxin determined by single wavelength anomalous diffraction phasing.

By using single wavelength anomalous diffraction phasing based on the anomalous signal from copper atoms, the crystal structure of atratoxin was determined at the resolution of 1.5 A and was refined to an ultrahigh resolution of 0.87 A. The ultrahigh resolution electron density maps allowed the modeling of 38 amino acid residues in alternate conformations and the location of 322 of 870 possible hydrogen atoms. To get accurate information at the atomic level, atratoxin-b (an analog of atratoxin with reduced toxicity) was also refined to an atomic resolution of 0.92 A. By the sequence and structural comparison of these two atratoxins, Arg(33) and Arg(36) were identified to be critical to their varied toxicity. The effect of copper ions on the distribution of hydrogen atoms in atratoxin was discussed, and the interactions between copper ions and protein residues were analyzed based on a statistical method, revealing a novel pentahedral copper-binding motif.

Amino Acid Motifs↗

PubMed1999

High-resolution magnetic resonance imaging in patients with facial haemiatrophy.

The aim of this clinical study was to evaluate the use of high-resolution magnetic resonance imaging (MRI) in the diagnosis of facial haemiatrophy. A total of 14 patients with clinically suspected facial haemiatrophy were investigated using high-resolution MRI. The T1- (500/25) and T2- (2200/50) weighted images were analysed visually and numerically. The results of the affected skin portions were compared with the contralateral skin and correlated with the clinical results. The subcutis could not be delineated by high-resolution MRI in 9 patients with facial haemiatrophy. The dermis was not discernible in 6 cases and was "smooth" in a further 6 patients. The signal-to-noise ratio of affected skin portions and contralateral skin or clinical severity did not correlate. The higher the clinical severity, the more pronounced was the magnetic resonance ratio between dermis and subcutis thickness. Thus high-resolution MRI is a useful method for objective description of pathological changes in clinically suspected facial haemiatrophy.

Adult↗

PubMed1987

Yeast tRNA(Asp)-aspartyl-tRNA synthetase complex: low resolution crystal structure.

Yeast aspartyl-tRNA synthetase, a dimer of molecular weight 125,000, and two molecules of its cognate tRNA (Mr = 24160) cocrystallize in the cubic space group I432 (a = 354 A). The crystal structure was solved to low resolution using neutron and X-ray diffraction data. Neutron single crystal diffraction data were collected in five solvents differing by their D2O content in order to use the contrast variation method to distinguish between the protein and tRNA. The synthetase was first located at 40 A resolution using the 65% D2O neutron data (tRNA matched) tRNA molecules were found at 20 A resolution using both neutron and X-ray data. The resulting model was refined against 10 A resolution X-ray data, using density modification and least-squares refinement of the tRNA positions. The crystal structure solved without a priori phase knowledge, was confirmed later by isomorphous replacement. The molecular model of the complex is in good agreement with results obtained in solution by probing the protected part of the tRNA by chemical reagents.

Amino Acyl-tRNA Synthetases↗

PubMed1999

Incidence, ultrasonic patterns and resolution of nephrocalcinosis in very low birthweight infants.

This longitudinal study was undertaken in order to elucidate the incidence and natural course of nephrocalcinosis in preterm infants and to evaluate whether the ultrasonic classification for nephrocalcinosis used here is suitable for predicting subsequent resolution of the condition. A total of 129 very low birthweight infants were screened for nephrocalcinosis by renal ultrasonography at 2 wk, 6 wk and 3 mo. The pyramidal changes were classified as peripheral, scattered or extensive. Follow-up renal ultrasonography was performed on the infants with nephrocalcinosis at 6, 12, 18 and 24 mo, and thereafter annually up to 6 y of age, or until ultrasonic resolution. The overall incidence of nephrocalcinosis was 20% (26/129). Nephrocalcinotic changes were peripheral in 14 out of the 26 infants (54%), scattered in 7 (27%) and extensive in 5 (19%). Ultrasonic resolution had taken place in all the cases with peripheral nephrocalcinosis by 12 mo, but 3 of the 7 infants with the scattered pattern and 3 of the 4 with the extensive pattern (1 died) were still affected at 24 mo. In two cases with extensive nephrocalcinosis the condition still persisted at 5-6 y of age. We conclude that about 20% of very low birthweight infants develop nephrocalcinosis during the first 3 mo of life. In about half of the affected infants renal changes are restricted and transient, but more extensive forms may last several years. The classification of nephrocalcinosis used here is appropriate for predicting later ultrasonic resolution.

Anti-Inflammatory Agents↗

PubMed2003

Assessing the role of neutrophil apoptosis in the resolution of particle-induced pulmonary inflammation.

Following inflammatory-cell recruitment in the lung, neutrophil apoptosis and subsequent engulfment by macrophages are regarded as important components in the resolution of pulmonary inflammation. The goal of this study was to further investigate the role of apoptosis and its influence, if any, on the pulmonary inflammatory process following exposures to the following particulate types: amorphous (AMO) or crystalline silica (Si), lipopolysaccharide (LPS), or pigment-grade titanium dioxide (TiO2). Rats were intratracheally instilled either with TiO2, AMO, or Si particles at doses of 1 or 5 mg/kg or 6 microg LPS. Following exposures, bronchoalveolar lavage fluids and lung tissues were collected and evaluated at 12, 24, 48, or 168 h (i.e., 1 wk). At the 1 mg/kg dose, AMO instillation produced the highest pulmonary inflammatory response, concomitant with a rise in apoptotic cells that mirrored temporally the transient nature of the inflammatory response. At 5 mg/kg, amorphous silica and crystalline silica particles induced substantial pulmonary inflammation [approximately 50-60% neutrophils (PMNs)] at 12 h postexposure (pe). A fundamental difference between the two inflammatory patterns, however, was the subsequent reversibility of inflammation in the AMO-exposed rats at 168 h postexposure and the sustained inflammatory effect in the Si-exposed animals measured through 168 h pe (approximately 40% PMNs). Pulmonary apoptotic responses in AMO-exposed rats mirrored temporally and correlated with the time-course reduction of inflammatory responses, leading to resolution. In the Si-exposed rats, apoptotic levels remained elevated, concomitant with sustained inflammation measured through 168 h pe. High doses of TiO2 particles produced transient lung inflammation, but with low levels of apoptosis. In addition, instillation of LPS produced a transient inflammatory response which mirrored the time course of apoptosis levels and was resolved by 168 h pe. cDNA microarray methods demonstrated that gene expression was altered for several apoptosis-related genes in AMO-, Si-, and LPS-exposed animals at 24 h pe. The results of these studies demonstrate that, following exposures, the resolution of lung inflammation correlated temporally with apoptotic levels of neutrophils in AMO- and LPS-exposed rats. Alternatively, instillation of crystalline silica resulted in sustained pulmonary inflammation and measurable apoptosis at 1 wk postexposure, but the apoptotic cell processes were not effective in resolving the inflammatory response. The findings suggest that the coordination between the resolution of inflammation and inflammatory cell apoptosis in the lung is dependent on the particle-type and that other factors, such as particle cytotoxicity, may also be important.

Animals↗

PubMed2005

Control of ozone precursors in a complex industrial terrain by using multiscale-nested air quality models with fine spatial resolution (1 km2).

The location of the northeastern Iberian Peninsula (NEIP) in the northwestern Mediterranean basin, the presence of the Pyrenees mountain range (with altitudes > 3000 m), and the influence of the Mediterranean Sea and the large valley canalization of Ebro river induce an extremely complicated structure for the dispersion of photochemical pollutants. Air pollution studies in very complex terrains such as the NEIP require high-resolution modeling for resolving the very complex dynamics of flows. To deal with the influence of larger-scale transport, however, high-resolution models have to be nested in larger models to generate appropriate initial and boundary conditions for the finer resolution domains. This article shows the results obtained through the utilization of the MM5-EMICAT2000-CMAQ multiscale-nested air quality model relating the sensitivity regimes for ozone (O3)-nitrogen oxides (NOx)-volatile organic compounds (VOCs) in an area of high geographical complexity, like the industrial area of Tarragona, located in the NEIP. The model was applied with fine temporal (one-hour) and spatial resolution (cells of 24 km, 2 km, and 1 km) to represent the chemistry and transport of tropospheric O3 and other photochemical species with respect to different hypothetical scenarios of emission controls and to quantify the influence of different emission sources in the area. Results indicate that O3 chemistry in the industrial domain of Tarragona is strongly sensitive to VOCs; the higher percentages of reduction for ground-level O3 are achieved when reducing by 25% the emissions of industrial VOCs. On the contrary, reductions in the industrial emissions of NOx contribute to a strong increase in hourly peak levels of O3. At the same time, the contribution of on-road traffic and biogenic emissions to ground-level O3 concentrations in the area is negligible with respect to the pervasive weight of industrial sources. This analysis provides an assessment of the effectiveness of different policies for the control of emission of precursors by comparing the modeled results for different scenarios.

Air Pollutants↗

PubMed2004

Husbands' and wives' marital quality: the role of adult attachment orientations, depressive symptoms, and conflict resolution behaviors.

Although previous research has examined the role of adult attachment orientations, depressive symptoms, and conflict resolution behaviors (attacking and compromising) in marital quality, these variables have typically been considered separately. In the present study, these attributes were examined together in a community sample of 64 married couples. Correlational analyses revealed significant associations among the study variables and generally supported the hypothesized relations. When a regression series was applied to the data in order to examine indirect links between husbands' and wives' attachment orientations and their marital satisfaction, results provided some support for mediation; husbands' conflict resolution behaviors partially mediated the association between husbands' depressive symptoms and marital satisfaction. Interestingly, wives' conflict resolution behaviors did not mediate the association between wives' depressive symptoms and marital satisfaction. Instead, a different pattern was found; wives' conflict resolution behaviors partially mediated the association between wives' attachment anxiety and marital satisfaction. Findings highlight the importance of considering husbands' and wives' attributes separately and suggest directions for future research on this topic.

Adult↗