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Cornea Jun 2020To compare the degree of corneal light scatter as measured by densitometry in ultrathin Descemet Stripping Automated Endothelial Keratoplasty (UT-DSAEK) and Descemet... (Randomized Controlled Trial)
Randomized Controlled Trial
Corneal Light Scatter After Ultrathin Descemet Stripping Automated Endothelial Keratoplasty Versus Descemet Membrane Endothelial Keratoplasty in Descemet Endothelial Thickness Comparison Trial: A Randomized Controlled Trial.
PURPOSE
To compare the degree of corneal light scatter as measured by densitometry in ultrathin Descemet Stripping Automated Endothelial Keratoplasty (UT-DSAEK) and Descemet Membrane Endothelial Keratoplasty (DMEK) in the Descemet endothelial thickness comparison trial.
METHODS
This was a prespecified secondary analysis of the Descemet endothelial thickness comparison trial, which was a prospective, randomized controlled trial. Subjects with isolated endothelial dysfunction were enrolled and were randomized to either UT-DSAEK or DMEK. Corneal opacity was quantitatively measured by Pentacam densitometry (OCULUS) at 3, 6, and 12 months.
RESULTS
Fifty eyes of 38 patients were enrolled at the Casey Eye Institute at Oregon Health & Science University and the Byers Eye Institute at Stanford University. Corneal densitometry for the anterior and posterior layers improved in both UT-DSAEK and DMEK after surgery. The decrease was more pronounced in the posterior layer for both groups. However, there was no difference in the degree of corneal light scatter between UT-DSAEK and DMEK at postoperative month 12, and no difference in change in densitometry was observed between the 2 arms from baseline to month 12.
CONCLUSIONS
Both UT-DSAEK and DMEK experience an improvement in the degree of corneal light scatter after surgery. However, there was no difference in densitometry between the 2 groups at month 12. Therefore, other factors such as higher order aberrations in the posterior cornea rather than stromal-stromal interface haze mediate the superior visual outcomes in DMEK compared with UT-DSAEK.
Topics: Aged; Aged, 80 and over; Cell Count; Densitometry; Descemet Stripping Endothelial Keratoplasty; Endothelium, Corneal; Female; Follow-Up Studies; Fuchs' Endothelial Dystrophy; Humans; Male; Middle Aged; Postoperative Complications; Prospective Studies; Visual Acuity
PubMed: 31939923
DOI: 10.1097/ICO.0000000000002256 -
The Journal of Physiology Jan 19711. Atypical (blue cone) monochromats show two action spectra when tested by the increment threshold method of Stiles with ;central' fixation. One spectrum peaks near 450...
1. Atypical (blue cone) monochromats show two action spectra when tested by the increment threshold method of Stiles with ;central' fixation. One spectrum peaks near 450 nm and has the spectral characteristics of normal blue cones. The other resembles rhodopsin (pi(0)) modified slightly by photostable macular pigment.2. Under some circumstances such observers are dichromats. There is a neutral point (matched to Illuminant ;C') in the neighbourhood of 460-470 nm.3. The spectral colour matching functions using two primaries have been measured on three such subjects. They can be fit reasonably well, although imperfectly, by linear combinations of pi(0) and pi(1). The chromaticity co-ordinates have been calculated according to the convention of W. D. Wright and compared to the results predicted from pi(0) and pi(1). The comparison suggests that part of the imperfections of the colour matching function fit is due to prereceptor differences (e.g. macular pigment) between the blue-cone monochromats and the hypothetical pi(0), pi(1) observer.4. Colour matches made at high light levels continue to hold when the intensity of the field is reduced below the cone threshold.5. Therefore one of the visual pigments participating in the colour matches has an action spectrum which is not measurably different from that of the rod pigment rhodopsin.6. Increment threshold measurements show that the mechanism which has the rhodopsin action spectrum has the directional sensitivity of cones, not rods.7. Blue test threshold during dark adaptation after a full bleach follow a bipartite exponential recovery curve. The first exponential has a time constant of 1 min, the second 2 min. By comparing these curves to the increment thresholds it is possible to relate the first to the pi(1), the second to the pi(0) cones.8. Using a broad band blue gelatin filter in the measuring light of the retinal densitometer and studying the same retinal region tested in 7 it is possible to follow the regeneration of a pigment after a full bleach which has an exponential recovery with a time constant of 1.0 min. With a yellow green filter in the measuring light the exponential recovery observed after a full bleach has a time constant of 2.0 min.9. One of the two visual pigments participating in the colour matches resides in receptors which have the action spectrum, the directional sensitivity and probably the dark adaptation curve of normal blue cones.10. The other resides in receptors which have the action spectrum of normal rods but the directional sensitivity and the dark adaptation curve of normal red and green cones.
Topics: Color Perception; Color Vision Defects; Densitometry
PubMed: 5313219
DOI: 10.1113/jphysiol.1971.sp009318 -
The Journal of Physiology Jun 19751. Human rhodopsin in vivo was flash bleached by a 600 musec xenon flash which could deliver to the retina up to 15 rod-equivalent quanta per rhodopsin molecule, and the...
1. Human rhodopsin in vivo was flash bleached by a 600 musec xenon flash which could deliver to the retina up to 15 rod-equivalent quanta per rhodopsin molecule, and the fraction bleached measured by fundus reflexion densitometry. 2. The curve relating fraction rhodopsin bleached to intensity of flash saturates at 0.5 to 0.6. Thus, 40-50% of the rhodopsin is left photo-regenerated by the brightest flashes. 3. Three types of densitometry experiments confirm the saturation of the bleaching curve. 4. The kinetic constants required to account for the observed photo-regeneration were somewhat discrepant with in vitro and in situ estimates from infrahuman species. Specifically, (i) the quantum efficiency of the back reaction, metarhodopsin I hv leads to rhodopsin, was inferred to be nearly as high as that of the forward reaction; and (ii) the rate of the metarhodopsin I leads to metarhodopsin II dark reaction was inferred to be less than 500 sec(-1).
Topics: Densitometry; Humans; Kinetics; Models, Chemical; Photolysis; Regeneration; Retina; Retinal Pigments; Rhodopsin; Xenon
PubMed: 1151790
DOI: 10.1113/jphysiol.1975.sp010981 -
Current Oncology (Toronto, Ont.) Dec 2021Dense breasts are a risk factor for breast cancer. Assessment of breast density is important and radiologist-dependent. We objectively measured mammographic density...
Dense breasts are a risk factor for breast cancer. Assessment of breast density is important and radiologist-dependent. We objectively measured mammographic density using the three-dimensional automatic mammographic density measurement device Volpara™ and examined the criteria for combined use of ultrasonography (US). Of 1227 patients who underwent primary breast cancer surgery between January 2019 and April 2021 at our hospital, 441 were included. A case series study was conducted based on patient age, diagnostic accuracy, effects of mammography (MMG) combined with US, size of invasion, and calcifications. The mean density of both breasts according to the Volpara Density Grade (VDG) was 0-3.4% in 2 patients, 3.5-7.4% in 55 patients, 7.5-15.4% in 173 patients, and ≥15.5% in 211 patients. Breast density tended to be higher in younger patients. Diagnostic accuracy of MMG tended to decrease with increasing breast density. US detection rates were not associated with VDG on MMG and were favorable at all densities. The risk of a non-detected result was high in patients without malignant suspicious calcifications. Supplementary use of US for patients without suspicious calcifications on MMG and high breast density, particularly ≥25.5%, could improve the breast cancer detection rate.
Topics: Breast Density; Breast Neoplasms; Densitometry; Female; Humans; Mammography
PubMed: 34940087
DOI: 10.3390/curroncol28060448 -
Annals of Botany Nov 2019Tree rings, as archives of the past and biosensors of the present, offer unique opportunities to study influences of the fluctuating environment over decades to...
BACKGROUND AND AIMS
Tree rings, as archives of the past and biosensors of the present, offer unique opportunities to study influences of the fluctuating environment over decades to centuries. As such, tree-ring-based wood traits are capital input for global vegetation models. To contribute to earth system sciences, however, sufficient spatial coverage is required of detailed individual-based measurements, necessitating large amounts of data. X-ray computed tomography (CT) scanning is one of the few techniques that can deliver such data sets.
METHODS
Increment cores of four different temperate tree species were scanned with a state-of-the-art X-ray CT system at resolutions ranging from 60 μm down to 4.5 μm, with an additional scan at a resolution of 0.8 μm of a splinter-sized sample using a second X-ray CT system to highlight the potential of cell-level scanning. Calibration-free densitometry, based on full scanner simulation of a third X-ray CT system, is illustrated on increment cores of a tropical tree species.
KEY RESULTS
We show how multiscale scanning offers unprecedented potential for mapping tree rings and wood traits without sample manipulation and with limited operator intervention. Custom-designed sample holders enable simultaneous scanning of multiple increment cores at resolutions sufficient for tree ring analysis and densitometry as well as single core scanning enabling quantitative wood anatomy, thereby approaching the conventional thin section approach. Standardized X-ray CT volumes are, furthermore, ideal input imagery for automated pipelines with neural-based learning for tree ring detection and measurements of wood traits.
CONCLUSIONS
Advanced X-ray CT scanning for high-throughput processing of increment cores is within reach, generating pith-to-bark ring width series, density profiles and wood trait data. This would allow contribution to large-scale monitoring and modelling efforts with sufficient global coverage.
Topics: Densitometry; Tomography, X-Ray Computed; Wood; X-Rays
PubMed: 31361809
DOI: 10.1093/aob/mcz126 -
Journal of Bone and Mineral Research :... Apr 2002As part of an effort to quantify device-dependent differences in forearm bone density, 101 women, aged 20-80 years (approximately 16 women in each age decade), were...
As part of an effort to quantify device-dependent differences in forearm bone density, 101 women, aged 20-80 years (approximately 16 women in each age decade), were scanned on six forearm bone densitometers: the Aloka DCS-600EX, the Hologic QDR-4500A, the Lunar PIXI, the Norland pDEXA, the Osteometer DTX-200, and the Pronosco X-posure System. Regression statistics are reported for all similar regions of interest (ROIs). However, comparisons were confounded because of large differences in the ROI size and placement. The number of ROIs reported for a single scan by each device varied from 1 to 12. The correlation coefficients ranged from 0.7 < r < 0.97, with the highest correlation coefficients and lowest SEs for comparisons between the most similar ROIs. Standardized units of bone mineral density are derived for distal (sdBMD), mid-(smBMD), and proximal (spBMD) ROTs that allow for comparable mean bone densities to be derived for patient populations. Five phantoms were scanned and characterized on five of the devices and the precision and mean values were reported. These phantom values will aid in the in vitro cross-calibration between manufacturers to recreate the presented in vivo relationships. Care should be exercised when using these equations for cross-calibrating patient databases or pooling clinical data from different devices because the least significant differences detectable from measurements taken on two different machines can be increased substantially.
Topics: Absorptiometry, Photon; Adult; Aged; Aged, 80 and over; Bone Density; Female; Forearm; Humans; Middle Aged; Phantoms, Imaging; Reference Values
PubMed: 11918231
DOI: 10.1359/jbmr.2002.17.4.734 -
Nature Nanotechnology Apr 2015Mass sensing with nanoelectromechanical systems has advanced significantly during the last decade. With nanoelectromechanical systems sensors it is now possible to carry...
Mass sensing with nanoelectromechanical systems has advanced significantly during the last decade. With nanoelectromechanical systems sensors it is now possible to carry out ultrasensitive detection of gaseous analytes, to achieve atomic-scale mass resolution and to perform mass spectrometry on single proteins. Here, we demonstrate that the spatial distribution of mass within an individual analyte can be imaged--in real time and at the molecular scale--when it adsorbs onto a nanomechanical resonator. Each single-molecule adsorption event induces discrete, time-correlated perturbations to all modal frequencies of the device. We show that by continuously monitoring a multiplicity of vibrational modes, the spatial moments of mass distribution can be deduced for individual analytes, one-by-one, as they adsorb. We validate this method for inertial imaging, using both experimental measurements of multimode frequency shifts and numerical simulations, to analyse the inertial mass, position of adsorption and the size and shape of individual analytes. Unlike conventional imaging, the minimum analyte size detectable through nanomechanical inertial imaging is not limited by wavelength-dependent diffraction phenomena. Instead, frequency fluctuation processes determine the ultimate attainable resolution. Advanced nanoelectromechanical devices appear capable of resolving molecular-scale analytes.
Topics: Acceleration; Accelerometry; Biosensing Techniques; Computer-Aided Design; Densitometry; Equipment Design; Equipment Failure Analysis; Micro-Electrical-Mechanical Systems; Molecular Imaging; Nanotechnology; Reproducibility of Results; Sensitivity and Specificity
PubMed: 25822931
DOI: 10.1038/nnano.2015.32 -
Journal of Lipid Research Jan 1966The disc electrophoresis of lipoproteins of unfractionated rat plasma is described. The plasma was prestained with Sudan black B and electrophoretically separated at...
The disc electrophoresis of lipoproteins of unfractionated rat plasma is described. The plasma was prestained with Sudan black B and electrophoretically separated at polyacrylamide gel concentrations of 7.5, 5, and 3.75%. At least four lipoprotein components were observed, and an additional 2-3 components in the main gel and 2-5 components in the spacer gel possibly were present. Densitometry of the resolved gel patterns indicated good reproducibility. Thin-layer chromatography of lipids extracted from the Sudan black B-binding components confirmed the lipoprotein nature of these components of rat plasma. A comparison of the disc electrophoretic patterns of human serum and rat plasma suggested that the low-density lipoprotein components of rat plasma are smaller in size than those of human serum.
Topics: Animals; Blood Protein Electrophoresis; Chromatography, Thin Layer; Densitometry; Humans; In Vitro Techniques; Lipoproteins; Photometry; Rats; Staining and Labeling; Ultracentrifugation
PubMed: 4158523
DOI: No ID Found -
Acta Ortopedica Mexicana 2018Osteoporosis is a public health problem worldwide, affecting more than 200 million people. It is estimated that 30 to 50% of postmenopausal women suffer from it.... (Observational Study)
Observational Study
BACKGROUND
Osteoporosis is a public health problem worldwide, affecting more than 200 million people. It is estimated that 30 to 50% of postmenopausal women suffer from it. According to the International Osteoporosis Foundation (IOF), osteoporosis is a disease characterized by a decrease in the density and quality of bones. The objective of this work was to know the prevalence of osteoporosis and osteopenia in healthy active workers.
METHODS
Retrospective, observational study with active male and female workers in whom bone mineral density was evaluated by dual X-ray absorptiometry (DXA) of the hip and spine. The evaluation time was from June 2009 to June 2010.
RESULTS
A total of 1,431 patients were recruited: 258 (18%) men and 1,173 (82%) women. According to the international parameters, the diagnoses of the central densitometries were, overall: 572 normal subjects (40%), 601 (42%) with osteopenia and 258 (18%) with osteoporosis.
DISCUSSION
The results show that degenerative alterations in patients with osteoporosis or osteopenia are frequent, even among young people.
Topics: Absorptiometry, Photon; Bone Diseases, Metabolic; Female; Humans; Male; Osteoporosis; Prevalence; Retrospective Studies
PubMed: 30521703
DOI: No ID Found -
Respiratory Research Nov 2022Idiopathic pulmonary fibrosis, the archetype of pulmonary fibrosis (PF), is a chronic lung disease of a poor prognosis, characterized by progressively worsening of lung...
Idiopathic pulmonary fibrosis, the archetype of pulmonary fibrosis (PF), is a chronic lung disease of a poor prognosis, characterized by progressively worsening of lung function. Although histology is still the gold standard for PF assessment in preclinical practice, histological data typically involve less than 1% of total lung volume and are not amenable to longitudinal studies. A miniaturized version of computed tomography (µCT) has been introduced to radiologically examine lung in preclinical murine models of PF. The linear relationship between X-ray attenuation and tissue density allows lung densitometry on total lung volume. However, the huge density changes caused by PF usually require manual segmentation by trained operators, limiting µCT deployment in preclinical routine. Deep learning approaches have achieved state-of-the-art performance in medical image segmentation. In this work, we propose a fully automated deep learning approach to segment right and left lung on µCT imaging and subsequently derive lung densitometry. Our pipeline first employs a convolutional network (CNN) for pre-processing at low-resolution and then a 2.5D CNN for higher-resolution segmentation, combining computational advantage of 2D and ability to address 3D spatial coherence without compromising accuracy. Finally, lungs are divided into compartments based on air content assessed by density. We validated this pipeline on 72 mice with different grades of PF, achieving a Dice score of 0.967 on test set. Our tests demonstrate that this automated tool allows for rapid and comprehensive analysis of µCT scans of PF murine models, thus laying the ground for its wider exploitation in preclinical settings.
Topics: Animals; Mice; Deep Learning; Pulmonary Fibrosis; X-Ray Microtomography; Disease Models, Animal; Densitometry
PubMed: 36369209
DOI: 10.1186/s12931-022-02236-x