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At least 1,585 records · Page 88Linked to original sources
PubMed1985

Fringe patterns and measurement on dorsal moiré topography in Japanese children, aged 13 and 14.

Dorsal moiré topographies of 165 boys and 156 girls, aged 13 and 14, were investigated. Moiré fringe patterns were classified into seven types, of which type IV, thin and symmetric back, was most frequent (29% in boys and 22% in girls), and types I and II thoracic, fleshy back, were observed in 15% of boys and 29% of girls. Settling four prominent points on the back, length, depth (number of fringes), angles between these points, and the most depressed point on the lumbar region were measured. Neither bilateral or sex differences were detected in length and depth measurements, whereas larger right side angles were observed as a general tendency. In both sexes, significant correlation was detected between measurements on points situated in the inner part of the back, while on points situated in the outer parts only angle and length correlation was significant.

Adolescent↗
PubMed2007

Ubiquitin binds to a short peptide segment of hydrolase UCH-L3: a study by FCS, RIfS, ITC and NMR.

Screening for small peptidic affinity tags for the detection of ubiquitin and ubiquitinated proteins yielded the dodecapeptide amide DPDELRFNAIAL-NH(2) as a specific ubiquitin-interacting ligand. A peptide collection--based on crystal structures with ubiquitin-interacting proteins--was designed and confirmed by sequence comparison of ubiquitin-interacting motifs. Four independent physical detection methods demonstrated that the peptide binds to monomeric ubiquitin with an affinity of about 10 muM and with fast on and off rates. Fluorescence correlation spectroscopy with fluorescent peptides showed specific interaction with ubiquitin. Reflectometric interference spectroscopy with surface-immobilized peptides and isothermal calorimetry measurements confirmed the specific binding of ubiquitin and fast rate constants. (1)H,(15)N heteronuclear NMR localised the interaction site across the beta sheet of ubiquitin. The peptide aligns well with the ubiquitin-interacting motif and represents a lead structure for the rational design of high-affinity tags for targeting ubiquitinated protein in vitro and in vivo.

Amino Acid Sequence↗
PubMed2004

High-resolution imaging of the thyroid gland using optical coherence tomography.

BACKGROUND: Current diagnostic imaging modalities of the thyroid gland cannot reliably distinguish benign from malignant lesions, primarily because of their inability to visualize microscopic structure. A high-resolution imaging technique capable of examining thyroid tissue architectural morphology in real time is needed. Optical coherence tomography (OCT) has been shown to achieve high resolutions approaching the cellular range (1-15 microm). The feasibility of optical coherence tomography for imaging thyroid tissue was explored ex vivo on the human thyroid gland. METHODS: High-resolution OCT was performed in real time at 2 to 4 frames per second on three postmortem and 15 surgically excised thyroid glands containing normal, hyperplastic, and neoplastic tissue. OCT images acquired were compared with those obtained using standard histopathologic methods. RESULTS: The microstructure of the normal thyroid gland, including colloid-filled follicles as small as 15 microm and their supporting stroma, was clearly identified. OCT images of degenerative, hyperplastic, adenomatous, and malignant change within the thyroid gland were shown to correlate well with corresponding histopathologic findings. CONCLUSIONS: The ability of OCT to image thyroid tissue microarchitecture makes it a potentially powerful technology that can be used to assess the thyroid gland at a resolution greater than currently available clinical imaging modalities.

Adult↗
PubMed2004

Ultracompact autocorrelator for multiphoton microscopy.

Pulse temporal characterization is a fundamental task when operating a Ti:Sapphire ultrafast laser system for multiphoton microscopy applications. In the present report, an ultracompact autocorrelator setup and a simple procedure is reported to perform pulse width measurements at the focal plane of the microscope objective without the need of any further instrumentation, aside from a few optical elements, since the confocal microscope, detection, data acquisition, processing, and displaying capabilities are used.

Equipment Design↗
PubMed2003

Imaging tissue response to electrical and photothermal stimulation with nanometer sensitivity.

BACKGROUND AND OBJECTIVES: Tissue response to thermal, electrical, or chemical stimuli are important in the health and survival of tissue. We report experimental results to assess tissue response to various stimuli using a low coherence differential phase interferometer. STUDY DESIGN/MATERIALS AND METHODS: The optical system utilized to measure tissue response is a novel fiber-based phase sensitive optical low coherence reflectometer (PS-OLCR). Inasmuch as the PS-OLCR works with back-reflected light, noninvasive sensing of tissue response to stimuli is possible. In addition to high lateral (approximately 10 microm) and longitudinal (approximately 10 microm) resolution, PS-OLCR can measure sub-wavelength changes in optical path-length (Angstrom/nanometer range) by extracting the phase difference between interference fringes in two channels corresponding to orthogonal polarization modes. RESULTS: When light spatially splits into two polarization states, precise analysis of surface topography or tissue surface response such as swelling or collapse are possible. Time resolved measurements of nanometer-scale path length changes in response to electrical and thermal stimuli are demonstrated using longitudinally delayed polarization channels. CONCLUSIONS: Since PS-OLCR is a useful tool to detect ultra-small path length changes, the system has potential to aid scientists in investigating important phenomena in biomaterials and developing useful diagnostic and therapeutic imaging modalities. Applications include tissue surface profilometry, measurement of tissue, and cell response to various stimuli, high-resolution intensity and phase imaging.

Animals↗
PubMed1991

Micron-resolution ranging of cornea anterior chamber by optical reflectometry.

Noncontact, high resolution measurements of anterior eye structures using optical coherence domain reflectometry are described. Distances between intraocular structures are measured by directing a beam of short coherence length light onto the eye and performing an interferometric measurement on the optical group delay of reflected signals. Measurements of corneal thickness, corneal excision depth, and anterior chamber depth are demonstrated in vitro, and the location of tissue boundaries is resolved to within +/- 2 microns. The full-width-half-maximum longitudinal resolution is 10 microns. Sensitivities to reflected signals as small as 10(-10) of the incident power are achieved by heterodyne detection.

Animals↗
PubMed1993

Slit lamp laser Doppler interferometer.

A slit lamp laser interferometer is described for clinical in vivo eye length measurements. The basic components are a laser Doppler interferometer, a slit lamp attachment, and a commercial slit lamp. First measurements of the axial length of the eye yielded a standard deviation of 0.04 mm and less.

Eye↗
PubMed1990

Generalized MR interferography.

Generalized MR interferography allows the measurement of parameters which affect the phase of the MR signal. Interference is generated by the simultaneous generation of two echoes in one excitation cycle. Local variations of the signal phase are transformed into displacement of the stripe pattern generated by interference. A number of possible experiments based on this principle are presented. The resulting interferographic images allow the fast determination of parameters such as field inhomogeneity, susceptibility, flow, and motion.

Fourier Analysis↗
PubMed1991

Double-volume 1H spectroscopy with interleaved acquisitions using tilted gradients.

A method is presented by which volume selective in vivo 1H spectra of two different voxels can be acquired in an interlaced mode using PRESS or STEAM spectroscopy. Spatially tilted gradients are employed for voxel definition so as to avoid mutual saturation. Independent volume selective shimming of the voxels is possible. Two spectra of volumes as small as (1.5 cm)3 can be acquired from human brain within 14 min even from very disadvantageous locations close to air-borne interfaces.

Adenoma↗
PubMed2001

Stretching short biopolymers using optical tweezers.

Optical tweezers is a useful technique to study single molecules. It has been applied to stretch biopolymers in several approaches. However, these approaches may not be appropriate to measure short biopolymers. In the present study, the optical signals of beads in different situations were studied. A new method was developed for stretching short biopolymers, as short as 300 nm in length. This new method was successfully applied to determine the stiffness of procollagen I molecules.

Biopolymers↗
PubMed1996

The effect of inhalation of different mixtures of O2 and CO2 on ocular fundus pulsations.

The effect of different mixtures of O2 and CO2 on pulsatile ocular blood flow as assessed by laserinterferometric measurement of fundus pulsations was studied. This was done in an effort to identify the gas mixture with an optimal O2/CO2 ratio for treatment in central retinal artery occlusion (CRAO). In a double-blind, randomized, placebo-controlled, six-way cross-over study, 20 healthy young subjects were studied. Fundus pulsation amplitude in the macula (FPAM) and in the optic disc (FPAO), arterialized capillary blood gases, and systemic haemodynamics were measured during baseline and 12 min inhalation periods of 100% O2, mixtures of 2.5%, 5%, 8%, 10% CO2 with oxygen, and air as placebo. The FPAM and FPAO decreased at 100% oxygen (FPAM: -6.2%, P < 0.01; FPAO: -15.1%. P < 0.001), but dose dependently increased with addition of CO2: whereas FPAM was not different versus placebo during inhalation of 2.5% CO2 with oxygen (+0.3%), addition of 5% CO2 and 8% CO2 to oxygen significantly increased FPAM versus placebo (+10.6%, P < 0.01 and +25.9%, P < 0.001, respectively), FPAO was slightly decreased by addition of 2.5% CO2 to oxygen (-2.6%, P < 0.05 versus placebo), 5% CO2 neutralized oxygen's effects on FPAO (+1.5%) and 8% CO2 + 92% O2 significantly increased FPAO (+16.0%, P < 0.001 versus placebo). Inhalation of 90% O2 + 10% CO2 was not tolerated by 19 subjects. Administration of 5% and 8% CO2 with oxygen significantly increased mean arterial pressure. We conclude that addition of 5% CO2 to oxygen is appropriate to maintain or even increase pulsatile ocular blood flow in the macula and optic disc at a level comparable to air-breathing. Addition of higher percentages of CO2 further increases fundus pulsations, with a very steep dose response relationship. Addition of 8% CO2 seems not applicable in patients due to pronounced systemic effects. Hence mixtures of 6 or 7% CO2 with oxygen should be used for further studies in patients with central retinal artery occlusion (CRAO).

Adult↗
PubMed1998

3D accordion spectroscopy for measuring 15N and 13CO relaxation rates in poorly resolved NMR spectra.

An experimental approach for the measurement of nuclear magnetic spin relaxation rate constants that combines triple-resonance techniques and accordion spectroscopy is described. Pulse sequences are discussed for the measurement of backbone 15N and 13CO R1 relaxation rate constants. The three-dimensional HNCO triple-resonance technique is employed to gain improved spectral resolution over conventional two-dimensional methods by frequency labeling both the 15N and 13CO spins. Accordion spectroscopy is used to reduce the dimensionality of the relaxation experiment. The "negative-time accordion" approach (A. M. Mandel and A. G. Palmer (1994), J. Magn. Reson. A 110, 62-72) is used for extracting rate constants from the t1 interferograms. The experiments are demonstrated using a 13C/15N isotopically enriched sample of the third fibronectin type III domain of human tenascin.

Algorithms↗
PubMed2005

Accurate image registration for quadrature tomographic microscopy.

This paper presents a robust and fully automated registration algorithm for registration of images of Quadrature Tomographic Microscopy (QTM), which is an optical interferometer. The need for registration of such images is to recognize distinguishing features of viable embryos to advance the technique for In Vitro Fertilization. QTM images a sample (live embryo) multiple times with different hardware configurations, each in turn producing 4 images taken by 4 CCD cameras simultaneously. Embryo movement is often present between imaging. Our algorithm handles camera calibration of multiple cameras using a variant of ICP, and elimination of embryo movement using a hybrid of feature- and intensity-based methods. The algorithm is tested on 20 live mouse embryos containing various cell numbers between 8 and 26. No failure thus far, and the average alignment error is 0.09 pixels, corresponding to the range of 639 and 675 nanometers.

Algorithms↗