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PubMed1998

Attention improves or impairs visual performance by enhancing spatial resolution.

Covert attention, the selective processing of visual information at a given location in the absence of eye movements, improves performance in several tasks, such as visual search and detection of luminance and vernier targets. An important unsettled issue is whether this improvement is due to a reduction in noise (internal or external), a change in decisional criteria, or signal enhancement. Here we show that attention can affect performance by signal enhancement. For a texture segregation task in which performance is actually diminished when spatial resolution is too high, we observed that attention improved performance at peripheral locations where spatial resolution was too low, but impaired performance at central locations where spatial resolution was too high. The counterintuitive impairment of performance that we found at the central retinal locations appears to have only one possible explanation: attention enhances spatial resolution.

Attention↗

PubMed2002

Three-dimensional X-ray structural microscopy with submicrometre resolution.

Advanced materials and processing techniques are based largely on the generation and control of non-homogeneous microstructures, such as precipitates and grain boundaries. X-ray tomography can provide three-dimensional density and chemical distributions of such structures with submicrometre resolution; structural methods exist that give submicrometre resolution in two dimensions; and techniques are available for obtaining grain-centroid positions and grain-average strains in three dimensions. But non-destructive point-to-point three-dimensional structural probes have not hitherto been available for investigations at the critical mesoscopic length scales (tenths to hundreds of micrometres). As a result, investigations of three-dimensional mesoscale phenomena--such as grain growth, deformation, crumpling and strain-gradient effects--rely increasingly on computation and modelling without direct experimental input. Here we describe a three-dimensional X-ray microscopy technique that uses polychromatic synchrotron X-ray microbeams to probe local crystal structure, orientation and strain tensors with submicrometre spatial resolution. We demonstrate the utility of this approach with micrometre-resolution three-dimensional measurements of grain orientations and sizes in polycrystalline aluminium, and with micrometre depth-resolved measurements of elastic strain tensors in cylindrically bent silicon. This technique is applicable to single-crystal, polycrystalline, composite and functionally graded materials.

Journal Article↗

PubMed1999

High-resolution mapping of quantitative trait loci in outbred mice.

Screening the whole genome of a cross between two inbred animal strains has proved to be a powerful method for detecting genetic loci underlying quantitative behavioural traits, but the level of resolution offered by quantitative trait loci (QTL) mapping is still too coarse to permit molecular cloning of the genetic determinants. To achieve high-resolution mapping, we used an outbred stock of mice for which the entire genealogy is known. The heterogeneous stock (HS) was established 30 years ago from an eight-way cross of C57BL/6, BALB/c, RIII, AKR, DBA/2, I, A/J and C3H inbred mouse strains. At the time of the experiment reported here, the HS mice were at generation 58, theoretically offering at least a 30-fold increase in resolution for QTL mapping compared with a backcross or an F2 intercross. Using the HS mice we have mapped a QTL influencing a psychological trait in mice to a 0.8-cM interval on chromosome 1. This method allows simultaneous fine mapping of multiple QTLs, as shown by our report of a second QTL on chromosome 12. The high resolution possible with this approach makes QTLs accessible to positional cloning.

Animals↗

PubMed2006

Cyclin-dependent kinase inhibitors enhance the resolution of inflammation by promoting inflammatory cell apoptosis.

Apoptosis is essential for clearance of potentially injurious inflammatory cells and subsequent efficient resolution of inflammation. Here we report that human neutrophils contain functionally active cyclin-dependent kinases (CDKs), and that structurally diverse CDK inhibitors induce caspase-dependent apoptosis and override powerful anti-apoptosis signals from survival factors such as granulocyte-macrophage colony-stimulating factor (GM-CSF). We show that the CDK inhibitor R-roscovitine (Seliciclib or CYC202) markedly enhances resolution of established neutrophil-dependent inflammation in carrageenan-elicited acute pleurisy, bleomycin-induced lung injury, and passively induced arthritis in mice. In the pleurisy model, the caspase inhibitor zVAD-fmk prevents R-roscovitine-enhanced resolution of inflammation, indicating that this CDK inhibitor augments inflammatory cell apoptosis. We also provide evidence that R-roscovitine promotes apoptosis by reducing concentrations of the anti-apoptotic protein Mcl-1. Thus, CDK inhibitors enhance the resolution of established inflammation by promoting apoptosis of inflammatory cells, thereby demonstrating a hitherto unrecognized potential for the treatment of inflammatory disorders.

Amino Acid Chloromethyl Ketones↗

PubMed2001

High resolution HLA class I and II typing and CTLp frequency in unrelated donor transplantation: a single-institution retrospective study of 69 BMTs.

UNLABELLED: The results of unrelated donor transplantation (URD-BMT) are difficult to analyze since the continuous advances in HLA typing technology allow the detection of new mismatches unknown at the time of transplantation. We sought to confirm that matched recipient-donor pairs are in fact often mismatched when advanced HLA typing techniques are used. We retrospectively studied the impact of the results of high resolution HLA typing for HLA class I (-A, -B, -C) and HLA class II (-DR, -DQ, -DP) loci, and cytotoxic T lymphocyte precursor (CTLp) frequency, on the outcome of 69 URD-BMT procedures. At the time of transplant, six (6/69) and two (2/69) donor-recipient pairs were mismatched for HLA class I (-A and -B by serology) and HLA class II, respectively, while one pair was mismatched for both HLA class I and II. Using high resolution DNA typing, HLA class I mismatches were found in 31 (45%) pairs and HLA class II mismatches in nine (13%) pairs. Twenty-three of the 69 pairs were HLA-C mismatched. Low CTLp frequencies were found among the 19 HLA class I matched pairs tested, and also in 5/14 mismatched pairs (of whom three had severe aGVHD). The overall survival of the cohort was 28 +/- 6%. Among the 33 patients who were fully matched with their donors, the survival rate was 66% in the 18 patients with a standard hematological risk and 9% in the 15 high risk patients. Only two of the 33 patients developed severe aGVHD, and only one had graft rejection. Among the 36 mismatched pairs, the survival rate was 31% in the 13 patients with a standard hematological risk and 8% in the 23 high risk patients. Sixteen of these 36 patients died from severe aGVHD and four had graft failure or rejection. Three of the 10 patients with only an HLA-C mismatch died from severe aGVHD, and two had graft rejection. IN CONCLUSION: (1) donor-recipient matching based on high resolution HLA class I and II DNA typing is associated with significantly better outcome after URD-BMT; (2) the results of URD-BMT with classical GVHD prevention are comparable to those of geno-identical BMT when donor and recipient are fully matched for HLA-A, -B, -C, -DRB1 and -DQB1 on the basis of high resolution typing; (3) CTLp frequencies do not correlate constantly with HLA class I matching, and our results fail to show that CTLp assay can distinguish between permissible and non-permissible class I mismatches; (4) clinical trials involving donor-recipient pairs with known HLA class I mismatches are needed to improve aGVHD prevention without increasing graft failure rate.

Adult↗

PubMed1992

Resolution of acute inflammation and the role of apoptosis in the tissue fate of granulocytes.

We have identified a pathway for granulocyte removal in tissues which is controlled by apoptosis. This process can be modulated by agents in the inflammatory microenvironment and leads to loss of neutrophil secretory function and its phagocytosis by macrophages which utilize a novel recognition mechanism such that the macrophage does not release pro-inflammatory mediators. It is hypothesized that this represents an alternative fate to necrosis, and one which would tend to limit tissue injury and promote inflammatory resolution. This is not to suggest that granulocyte necrosis does not occur; even at sites of 'beneficial inflammation' some necrotic neutrophils may be seen. However, since the development of inflammatory disease is currently thought to result from a multifactoral, quantitative imbalance between potentially injurious inflammatory influences and tissue defences, it is reasonable to suggest that the balance between neutrophil apoptosis and necrosis could represent one of several possible pivotal points in the control of inflammation. Finally, as the specific trigger and induction processes which permit closely related cells to undergo apoptosis at markedly different rates are uncovered, it may be possible to design new anti-inflammatory therapeutic strategies directed towards causing specific cell types to 'commit suicide' and to be cleared by the mechanisms which 'nature intended'. Thus we have begun to dissect the cellular events occurring in the resolution of acute inflammation. We believe that the rapid cessation of neutrophil emigration which occurs remarkably early in the evolution of the acute inflammatory response represents one of the earliest events in the resolution process. Clearly there is much work to be done on the underlying mechanisms. These are likely to be more accessible with the recent molecular characterization of chemotactic cytokines and surface molecules involved in neutrophil-endothelial adhesion transmigration events. It is also clear that apoptosis, which represents an alternative tissue injury-limiting fate to necrosis in situ, may be important in limiting tissue injury and determining whether inflammation persists or resolves. It is also possible that there are circumstances in which the macrophage recognition and clearance of apoptotic neutrophils is impaired. However, a second glance at the events which must occur during the resolution of even the simplest model of acute inflammation (Fig. 1) is sufficient reminder that the 'surface has barely been scratched'. There remain many obscure areas, not the least of which is the fate of the inflammatory macrophage after it has completed its scavenging functions.

Animals↗

PubMed1989

The relation between vowel recognition and measures of frequency resolution.

The purpose of this study was to employ measures of frequency resolution obtained from individual subjects to predict each subject's vowel recognition performance. Input filter patterns at six test frequencies were obtained from normal-hearing and hearing-impaired subjects. These patterns were used to correlate frequency resolution with vowel recognition in those same subjects. Vowels were presented at levels at which the entire spectrum was fully audible to each subject. Using each subject's measured filter characteristics (and interpolated values for intermediate frequencies), an "internal spectrum" of each vowel was calculated by determining the outputs of all filter channels for the vowel as the input signal. It was speculated that the more similar two internal spectra for a subject were, the more often they would be confused in the vowel recognition task. This expectation received some support when the measure of similarity was a point-by-point Euclidean distance between the two internal spectra. Stronger support was obtained when the measure of similarity was based upon Klatt's (1982) "weighted slope metric" that emphasizes similarities of spectral peak locations. The present study demonstrates a relation between impairments of frequency resolution and vowel recognition. The described filter-bank model of vowel recognition suggests that measures of frequency resolution along with the acoustic spectra of vowel stimuli may be useful in predicting the recognition of vowels by individuals.

Adult↗

PubMed1990

Speech reception in reverberation related to temporal resolution.

In this study, the influence of temporal properties of the auditory system on speech recognition, either in noise or in both noise and reverberation, has been investigated. Temporal resolution parameters consisted of both the temporal resolution factor (TRF) and the minimum detectable gap (MDG). TRFs were measured for probe-tone frequencies of 500, 1000, and 3000 Hz; MDGs were measured for octave-band noises centered at 500, 1000, and 3000 Hz and for a wideband noise. TRF and MDG proved to be rather independent parameters of temporal resolution. For both temporal-resolution parameters, there was considerable overlap between the performance of the normal-hearing and hearing-impaired listeners. A correlation analysis shows that MDG for wideband noise is related to speech recognition in reverberation. However, there is a mutual dependence of speech recognition and MDG on the pure-tone audiogram.

Adolescent↗

PubMed1999

Complete resolution of heartburn symptoms and health-related quality of life in patients with gastro-oesophageal reflux disease.

BACKGROUND: Medical treatments for gastro-oesophageal reflux disease (GERD) vary in their ability to completely resolve heartburn and other symptoms. Although GERD reduces health-related quality of life (HRQL) little is known about the relationship between resolution of heartburn symptoms with medical therapy and HRQL. We evaluated the association between complete resolution of heartburn symptoms and functioning and well-being in three samples of patients with GERD. METHODS: We analysed baseline and follow-up assessments of heartburn symptoms and HRQL scores from three clinical trials (total n=1351) comparing omeprazole and ranitidine for acute symptomatic treatment of GERD. Heartburn symptoms were measured using patient diaries and/or patient self-report. HRQL was assessed using the Psychological General Well-Being Index (PGWB) in all three clinical trials and the SF-36 Health Survey in two clinical trials. Resolution of heartburn symptoms was defined as no heartburn reported during the assessment period. RESULTS: We observed statistically significant differences favouring patients with no heartburn symptoms on the PGWB total score (P=0.018 to P < 0.0001) and anxiety (P=0.002 to P < 0.0001), general health (P=0.05 to P < 0. 0001), positive well-being (P=0.028 to P < 0.0001) and vitality (P=0. 05 to P < 0.0001) sub-scale scores at 4-14 weeks. Patients with no heartburn reported better SF-36 pain (P=0.005 to P < 0.0001) and general health perceptions (P=0.032 to P < 0.0001) compared with patients still experiencing heartburn symptoms at 4-24 weeks. SF-36 physical component summary scores were significantly better in patients with no heartburn symptoms compared with patients with heartburn symptoms at 4-24 weeks (P=0.013 to P=0.009), while mental component summary scores were only significantly different at 24 weeks (P=0.0005) in one of the two studies where the SF-36 was utilized. CONCLUSIONS: Complete resolution of heartburn symptoms was consistently associated with improvement in HRQL; the greatest impact was observed on measures of psychological well-being and physical functioning and well-being. Effective treatment of GERD that completely resolves heartburn results in clinically significant improvement in patient HRQL.

Anti-Ulcer Agents↗

PubMed2000

Surpassing the lateral resolution limit by a factor of two using structured illumination microscopy.

Lateral resolution that exceeds the classical diffraction limit by a factor of two is achieved by using spatially structured illumination in a wide-field fluorescence microscope. The sample is illuminated with a series of excitation light patterns, which cause normally inaccessible high-resolution information to be encoded into the observed image. The recorded images are linearly processed to extract the new information and produce a reconstruction with twice the normal resolution. Unlike confocal microscopy, the resolution improvement is achieved with no need to discard any of the emission light. The method produces images of strikingly increased clarity compared to both conventional and confocal microscopes.

Actins↗

PubMed2001

High resolution protein localization using soft X-ray microscopy.

Soft X-ray microscopes can be used to examine whole, hydrated cells up to 10 microm thick and produce images approaching 30 nm resolution. Since cells are imaged in the X-ray transmissive "water window", where organic material absorbs approximately an order of magnitude more strongly than water, chemical contrast enhancement agents are not required to view the distribution of cellular structures. Although living specimens cannot be examined, cells can be rapidly frozen at a precise moment in time and examined in a cryostage, revealing information that most closely approximates that in live cells. In this study, we used a transmission X-ray microscope at photon energies just below the oxygen edge (lambda = 2.4 nm) to examine rapidly frozen mouse 3T3 cells and obtained excellent cellular morphology at better than 50 nm lateral resolution. These specimens are extremely stable, enabling multiple exposures with virtually no detectable damage to cell structures. We also show that silver-enhanced, immunogold labelling can be used to localize both cytoplasmic and nuclear proteins in whole, hydrated mammary epithelial cells at better than 50 nm resolution. The future use of X-ray tomography, along with improved zone plate lenses, will enable collection of better resolution (approaching 30 nm), three-dimensional information on the distribution of proteins in cells.

3T3 Cells↗

PubMed2001

The relationship between early renal status, and the resolution of vesico-ureteric reflux and bladder function at 16 months.

OBJECTIVE: To examine, in infants presenting with vesico-ureteric reflux (VUR), the relationship between the presence of initial renal abnormalities with the outcome of VUR and bladder function at 16 months of age. PATIENTS AND METHODS: The study group comprised 40 infants (32 boys) presenting consecutively (29 after prenatal detection) with VUR grade III or greater (bilateral in 29) on the initial micturating cystogram (median age 8 weeks). The initial presence of abnormal kidneys was determined from isotopic renography and/or ultrasonography. These data were correlated with the outcome of VUR, from direct isotope cystography, and bladder function assessed by natural filling urodynamics, examined at age 16 months (mean 16.4 months, SD 2.1). RESULTS: Three groups were identified. Group 1 (eight boys and six girls) had normal kidneys bilaterally; initially grade III VUR was common. At 16 months bladder function was normal in 10 children and none had VUR (complete resolution). Group 2 (14 boys and two girls) had unilateral renal abnormalities; initially VUR was predominantly grade IV or grade V. At 16 months bladder function was normal in eight children and VUR resolved in eight, five of these with normal bladder function. Group 3 (10 boys) had bilateral renal abnormalities. Initially grade V VUR predominated; at 16 months the bladder function was normal in only one, and in the rest the emptying dynamics were abnormal. All 10 boys had persisting VUR (no resolution). CONCLUSIONS: In infants with moderate or severe VUR, resolution at 16 months old is associated with normal kidneys in a similar proportion of boys and girls. Resolution also correlates well with normal bladder function. Presentation in infancy with bilateral abnormal kidneys, associated with severe VUR in boys, is a poor prognostic sign for the early outcome of VUR and for bladder function.

Female↗

PubMedDate not supplied

Activation of phagocytes during initiation and resolution of mammary gland injury induced by lipopolysaccharide in heifers.

The object of the study was the comparative assessment of phagocyte activation during initiation and resolution of mammary gland injury induced by lipopolysaccharide (LPS) or buffered salt solution (PBS) on the basis of the CD14 receptor positivity. The experiments were carried out in 15 clinically normal Holstein x Bohemian Red Pied crossbred heifers, aged 14 to 18 months. Noninflammatory and inflammatory mammary gland injury were induced by intramammary administration of PBS (10 mL) and LPS (10 mL, 1 microg/mL), respectively. Samples of the cell populations were obtained by mammary lavages at 24 h intervals. Flow cytometry was used to determine the CD14+ neutrophils, monocytes, and macrophages. The percentage of CD14+ neutrophils was only 1.2% and 1.3% 24 h after the treatment with PBS and LPS, respectively. The resolution was accompanied by an increase in proportion of CD14+ neutrophils. The proportion of CD14+ neutrophils returned to initial values in the PBS-treated, but not in the LPS-treated mammary glands till 96 h. Percentage of CD14+ monocytes increased after 24 h and the effect was more pronounced in the LPS-treated than in the PBS treated mammary glands (P < 0.05). The percentage of CD14+ macrophages decreased highly significantly at 24 h in the LPS-treated, but not in the PBS-treated mammary glands (P < 0.01). The resolution of mammary gland injury (48 to 96 h) was characterised by an increase in CD14+ macrophages proportion, which was greater in the LPS-treated than PBS-treated mammary glands (P < 0.01). The activation of macrophages during resolution of mammary gland injury can be interpreted as an important mechanism of restitution.

Animals↗

PubMed2000

Does high-resolution MR imaging have better accuracy than standard MR imaging for evaluation of the triangular fibrocartilage complex?

We compared the findings of high-resolution MR imaging and standard MR imaging in the detection of tears of the triangular fibrocartilage in 33 patients with chronic wrist pain on the ulnar side. With arthroscopy as the standard of reference, sensitivity was 100%, specificity 53%, and accuracy 79% with the high-resolution MR imaging, against 83%, 67%, and 76% with the standard MR imaging. High-resolution MR imaging showed a higher sensitivity, but a decreased specificity in the assessment of the triangular fibrocartilage. The results showed that diagnosis of tears in the triangular fibrocartilage by MR imaging, even high-resolution MR imaging, is unsatisfactory, although further technological advances may well improve the accuracy.

Adult↗

PubMed2002

[Evaluation of TSE- and T1-3D-GRE-sequences for focal cartilage lesions in vitro in comparison to ultrahigh resolution multi-slice CT].

PURPOSE: Evaluation of TSE- and T 1 -3D-GRE-sequences for focal cartilage lesions in vitro in comparison to ultrahigh resolution multi-slice CT. MATERIALS AND METHODS: Forty artificial cartilage lesions in ten bovine patellae were immersed in a solution of iodinated contrast medium and assessed with ultrahigh resolution multi-slice CT. Fat-suppressed TSE images with intermediate- and T 2 -weighting at a slice thickness of 2, 3 and 4 mm as well as fat-suppressed T 1 -weighted 3D-FLASH images with an effective slice thickness of 1, 2 and 3 mm were acquired at 1.5 T. After adding Gd-DTPA to the saline solution containing the patellae, the T 1 -weighted 3D-FLASH imaging was repeated. RESULTS: All cartilage lesions were visualised and graded with ultrahigh resolution multi-slice CT. The TSE images had a higher sensitivity and a higher inter- and intraobserver kappa compared to the FLASH-sequences (TSE: 70 - 95 %; 0.82 - 0.83; 0.85 - 0.9; FLASH: 57.5 - 85 %; 0.53 - 0.72; 0.73 - 0.82, respectively). An increase in slice thickness decreased the sensitivity, whereby deep lesions were even reliably depicted on TSE images at a slice thickness of 3 and 4 mm. Adding Gd-DTPA to the saline solution increased the sensitivity by 10 % with no detectable advantage over the T 2 -weighted TSE images. CONCLUSION: TSE sequences and application of Gd-DTPA seemed to be superior to T 1 -weighted 3D-FLASH sequences without Gd-DTPA in the detection of focal cartilage lesions. The ultrahigh resolution multi-slice CT can serve as in vitro reference standard for focal cartilage lesions.

Animals↗

PubMed2005

[Digital mammography with high-resolution storage plates (CR) versus full-field digital mammography (CCD) (DR) for microcalcifications and focal lesions -- a retrospective clinical histologic analysis (n = 102)].

PURPOSE: To determine the diagnostic accuracy of microcalcifications and focal lesions in a retrospective clinical-histological study using high-resolution digital phosphor storage plates (hard copy) and full-field digital mammography (hard copy). MATERIALS AND METHODS: From May 2003 to September 2003, 102 patients underwent digital storage plate mammography (CR), using a mammography unit (Mammomat 3000 N, Siemens) in combination with a high resolution (9 lp/mm) digital storage phosphor plate system (pixel size 50 microm) (Fuji/Siemens). After diagnosis and preoperative wire localization, full-field digital mammography (CCD) (DR) was performed with the same exposure parameters. The full-field digital mammography used a CCD-detector (SenoScan) (Fisher Imaging) with a resolution of 10 Ip/mm and a pixel size of 50 microm. Five investigators determined the diagnosis (BI-RADS I - V) retrospectively after the operation from randomly distributed mediolateral views (hard copy reading). These results were correlated with the final histology. RESULTS: The diagnostic accuracy of digital storage plate mammography (CR) and full-field digital mammography (CCD) (DR) was 73 % and 71 % for all findings (n = 102), 73 % and 71 % for microcalcifications (n = 51), and 72 % and 70 % for focal lesions (n = 51). The overall results showed no difference. CONCLUSION: Our findings indicate the equivalence of high-resolution digital phosphor storage plate mammography (CR) and full-field digital mammography (CCD) (DR).

Adult↗

PubMed1994

[Indications for the application of a high resolution coil in MR tomography].

This is the first study with high spatial resolution Magnetic Resonance Imaging (MRI), performed with a high resolution coil in a clinical whole-body system. Measurements were recorded with a slice thickness of 2 mm. A 256 x 256 matrix and a 2.5 cm field of view were used resulting in a pixel size of 0.01 mm2. MR images of the skin, hand, wrist, knee and ankle of 14 healthy volunteers, of three anatomic pathology tissue specimens and of three formalin-fixed specimens were obtained. Normal anatomy was identified and compared with the three gross anatomic pathology sections. The skin, hands, wrists and ankles of 30 patients were examined and a variety of pathological lesions were detected, including cutaneous neoplasms and ulceration, acute and chronic tendon lesions and pathologic features of the bone and wrist. Based on the excellent imaging of anatomic detail and superior contrast resolution, high resolution MRI proved an important complement for preoperative diagnosis.

Adult↗

PubMed1983

[Effect of various parameters on the resolution potential behind obstructing fatty tissue in sonography].

Fat is one of the main disturbance factors in ultrasound. Experimental studies verify a deterioration of lateral and axial resolution with increasing thickness of overlapping fat. This is due to attenuation and phase distortion of ultrasound in fat. Experimental studies show a lesser deterioration of resolution behind fat (better results) with the following factors: large aperture transducers, compoundtechnique (the good axial resolution improves the wordes lateral resolution), great bandwidth of the ultrasound signal, compression of the fat and position of the fat in the focus of the transducer.

Adipose Tissue↗