[Etiology of diseases of the optic nerve of unknown origin with radiological examination of the optic canals].
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Disease↗
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[Diagnosis of enlargements of the optic canal; a tumor of the optic nerve spreading to the chiasma].
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Humans↗
Optical biopsy with optical coherence tomography: feasibility for surgical diagnostics.
BACKGROUND: Optical coherence tomography (OCT) is a recently developed compact technology which uses infrared light to perform cross-sectional imaging on a micrometer scale. Since OCT provides imaging at a resolution comparable to conventional histology and does not require direct contact with the tissue surface, a role in real-time surgical diagnostics represents a logical extension. In this work, we test the feasibility of OCT for surgical diagnostics by demonstrating imaging in tissue relevent to microsurgical intervention, a previously undescribed observation. MATERIALS AND METHODS: Over 50 sites on nervous, reproductive, and microvascular specimens from 10 patients were examined postmortem with OCT. After imaging, tissue was registered with microinjections of dye, under visible light laser guidance, followed by routine histologic processing to confirm the identity of microstructure. RESULTS: The 16 +/- 1 microm resolution allowed subsurface microstructure to be identified at unprecedented resolution. Structures identified included fascicles of peripheral nerves, the internal elastic membrane of microvessels, and the granular layer of the cerebellum. CONCLUSIONS: The ability of OCT to provide micrometer-scale definition of tissue microstructure suggests a role in surgical diagnostics. Future in vivo investigations are merited to establish its utility for morbidity reduction associated with surgical intervention.
Animals↗
Polarization optical investigation by topo-optical reactions of various blood platelet aggregates.
Phases I and II (early and advanced) of platelet aggregation could readily be followed and studied by various topo-optical reactions. Our studies indicate that in the early stage (monitored by an aggregometer) aggregates show no alteration in membrane structure of platelet. In the advanced stage (phase II), in addition to membrane alteration, platelets 2-3 times larger than in the control were observed. These were stained selectively in the pH 1-2 range with thiazine dyes. After hyaluronidase digestion they lost the ability to stain and became birefringent. The elucidation of this phenomenon requires further study.
Blood Platelets↗
On the reaction of adult Rhipicephalus evertsi mimeticus and Hyalomma truncatum to horizontally incidenting optical radiation of various wavelengths ranges and different irradiances and to optical radiation of a sun-simulating wavelength spectrum.
The valence of horizontally incidenting light/optical radiation for host-seeking-inclined ixodid ticks was investigated by exposing male and female adults of Rhipicephalus evertsi mimeticus and Hyalomma truncatum to narrow-band monochromatic radiation in the wavelength range of 300-801 nm at irradiances corresponding to an overcast to clear sunny day, a cloudy day and a full-moon night as well as to optical radiation of a sun-simulating wavelength spectrum of 190-2600 nm within a test chamber from which other stimuli were excluded. It was demonstrated that independent of sex, adult ticks of R. e. mimeticus and H. truncatum responded to a wide wavelength spectrum in the visible and UV range, even at irradiances corresponding to a full-moon night. Interspecific differences existed in the degree and extent of the response as well as in the spectral sensitivity. Ticks of H. truncatum consistently showed a faster and stronger response and reacted phototactically positively in higher percentages than adults of R. e. mimeticus. Independent of wavelength range and irradiance, predominantly only few R. e. mimeticus ticks were stimulated to positive phototaxis, whereas at least 33.3% (in most cases, 50%) and maximally greater than 80% of H. truncatum adults reacted phototactically positively. Spectral sensitivity maxima were demonstrated at the yellow and red light and at the UV-A waveband width for R. e. mimeticus and at the violet, blue, green and yellow light wavelength for H. truncatum. With decreasing irradiance, the spectral sensitivity shifted to the blue wavelength range.(ABSTRACT TRUNCATED AT 250 WORDS)
Animals↗
Optical properties of in vitro epidermis and their possible relationship with optical properties of in vivo skin.
Using a spectrophotometer with an internal integrating sphere, the absorption (mu a) and reduced scattering (mu s') coefficients of in vitro epidermis were evaluated from reflectance and transmittance measurements. mu a and mu s' varied from 24 to 0.2 cm-1, and from 32 to 21 cm-1 respectively, on passing from 400 to 800 nm. Moreover, using an external integrating sphere, the reflectance spectrum of in vivo skin was compared with the reflectance spectrum calculated with a Monte Carlo model, in which the mean values of mu a and mu s' and different anisotropy parameters were used as input data. In vivo results show that the principle of similarity is entirely valid for wavelengths greater than 600 nm and may be considered a good approximation in the 400-600 nm band, and suggest that optical characteristics of in vivo skin may be inferred from reflectance measurements.
Adipose Tissue↗
Spectral and optical studies of 2-amino-5-nitropyridinium dihydrogen phosphate: a semiorganic nonlinear optical material.
2-Amino-5-nitropyridinium dihydrogen phosphate (2A5NPDP) was synthesized and the molecular structure was elucidated by FT-IR, FT-Raman and FT-NMR. The proton and carbon configurations of 2A5NPDP was confirmed through FT-NMR technique. UV-vis-NIR spectrum was recorded and the optical transmittance region was identified as 350 nm. Single crystals were grown from ethanol by slow evaporation technique at 35 degrees C and the unit cell constants were determined. Bulk and powder second harmonic generation (SHG) measurements were carried out using Nd:YAG laser (lambda=1064 nm) and its phase matching condition was determined.
Aminopyridines↗
Ultrastructure of elastic fibers as shown by polarization optics after the topo-optical permanganate-bisulfite-toluidine blue (PBT) reaction.
Permanganate-bisulfite-toluidine blue (PBT) reaction proved to be a highly selective and sensitive method for demonstration of elastic structures in tissue sections. Permanganate oxidation liberates a great amount of aldehyde groups in young and adult elastic fibers both in bovine ligamentum nuchae which can be demonstrated with the bisulfite-toluidine blue (pH = 1.0) staining procedure. There are suggestive evidences that the aldehyde groups are liberated from the desmosine and isodesmosine cross bondings of elastin. The dichroism and the strong birefringence of the elastic fibers induced by the PBT reaction indicate a high degree of linear fibrillar molecular order of the reacting elastin molecules which are assumed to be arranged helically in the aortic elastic fibers and they are assumed to show 2 different micellar textures in ligamentum nuchae fibers as reported with other topo-optical reactions earlier by Romhanyi.
Adult↗
Comparison of optical zones in hyperopic laser in situ keratomileusis: 5.9 mm versus smaller optical zones.
PURPOSE: To compare the results of hyperopic laser in situ keratomileusis (LASIK) with a 5.9 mm optical zone (OZ) with those with smaller zones (4.4 to 5.5 mm). SETTING: Instituto de la Visión, Buenos Aires, Argentina. METHODS: The results of LASIK with a 5.9 mm OZ (147 cases) were compared with those in a previously reported group treated with OZs of 4.4 to 5.5 mm (679 cases). In the 5.9 mm group, 31.3% (46 eyes) had low hyperopia, 46.9% (69 eyes) had moderate hyperopia, and 21.8% (32 eyes) had high hyperopia. In the smaller OZ group, follow-up was 1 month in 79.4% (539 eyes), 3 months in 75.5% (501 eyes), 6 months in 68.5% (465 eyes), and 1 year in 38.3% (260 eyes). The hyperopic population studied was divided into 3 subgroups based on the preoperative spherical equivalents of the manifest refraction: subgroup A, low hyperopia: < or = +2.0 diopters (D); subgroup B, moderate hyperopia: +2.0 to +3.0 D; and subgroup C, high hyperopia: > +3.0 D. The following parameters were measured postoperatively: uncorrected visual acuity (UCVA), best corrected visual acuity (BCVA), refraction (evolution and distribution), and visual acuity lines gained and lost. RESULTS: The preoperative mean spherical equivalents in the 5.9 mm OZ group were +1.47 +/- 0.41 (SD) (subgroup A); +2.98 +/- 0.41 (subgroup B); and +5.13 +/- 0.61 (subgroup C). In the smaller OZ group, they were +1.31 +/- 0.74, +2.56 +/- 0.28, and +5.28 +/- 0. 69, respectively. At 12 months, the distribution of eyes in the 5.9 mm OZ group with refractions within +/-1.0 D were as follows: subgroup A, 100%; subgroup B, 100%; and subgroup C, 94.2%. In the smaller OZ group, the distributions were 100%, 95.3%, and 71.4%. In the 5.9 mm and the smaller OZ groups, the UCVA was 20/40 or better in 92.0% and 81.8% of eyes, respectively, in subgroup A; 94.6% and 100%, respectively, in subgroup B; and 76.5% and 77.9%, respectively, in subgroup C. The percentage of eyes with 0 +/- 1 line of BCVA 12 months after the procedure was also determined in the 5.9 mm OZ group and compared with the percentages in the smaller OZ group. CONCLUSION: Results of hyperopic LASIK with a 5.9 mm OZ in eyes with low, moderate, and high hyperopia are more stable, predictable, and safe than those in eyes with OZs smaller than 5.9 mm.
Adult↗
Optic flow: A brain region devoted to optic flow analysis?
The visual motion - or optic flow - that results from an observer's own movement can indicate the direction of heading through the environment. Recent experiments have strengthened the argument that neurons in a specialized region of the cerebral cortex are critical for the analysis of this important class of visual stimuli.
Animals↗
Polyhedral-based nonlinear optical materials. 2. Theoretical investigation of some new high nonlinear optical response compounds involving polyhedral bridges with charged aromatic donors and acceptors.
A theoretical study of several new classes of polyhedral-based molecules has shown that these species display large calculated nonlinear optical responses. These new classes of molecules are based on charged aromatic subunits connected through polyhedral cluster bridges, such as closo-[1-(C(7)H(6))-12-(C(5)Me(4))C(2)B(10)H(10)]. These compounds show calculated first hyperpolarizabilities (beta) ranging from 6.5 to 8413.9 x 10(-30) cm(5) esu(-1). A basis for understanding the origin of these large responses is proposed based on the two-state model and consideration of the orbital and electronic features of the molecules. In general, the highest occupied molecular orbitals for these species are localized on the aromatic donor rings, such as the cyclopentadienyl system, while the lowest unoccupied molecular orbitals are largely on the aromatic acceptor rings, such as the tropylium system. The electronic properties of these polyhedral-based systems appear to be significantly different from the analogous organic [5.6.7]quinarene system (tropyliumcyclopentadienylbenzene). The organic quinarene appears to behave as a completely electron-delocalized system over all three rings while the polyhedral-based compounds can best be described as consisting of two relatively independent, highly polarized regions.
Journal Article↗
Tuning the electrical and optical properties of dinuclear ruthenium complexes for near infrared optical sensing.
[reaction: see text] Redox-active dinuclear ruthenium complexes with various 1,2-dicarbonylhydrazido (DCH) ligands are designed and prepared to have intense absorption in the near-infrared region for potential optical sensing in aqueous media, as demonstrated for sensing hydrogen peroxide in this study.
Journal Article↗
Optical biopsy in human pancreatobiliary tissue using optical coherence tomography.
Optical coherence tomography (OCT) is a new technique for performing high-resolution, cross-sectional tomographic imaging in human tissue. OCT is analogous to ultrasound B mode imaging except that it uses light rather than acoustical waves. As a result, OCT has over 10 times the resolution of currently available clinical high-resolution cross-sectional imaging technologies. In this work, we investigate the capability of OCT to differentiate the architectural morphology of pancreatobiliary tissues. Normal pancreatobiliary tissues, including the gallbladder, common bile duct, pancreatic duct, and pancreas were taken postmortem and imaged using OCT. Images were compared to corresponding histology to confirm tissue identity. Microstructure was delineated in different tissues, including tissue layers, glands, submucosal microvasculature, and pancreatic islets of Langerhans. The ability of OCT to provide high-resolution imaging of pancreatobiliary architectural morphology suggests the feasibility of using OCT as a powerful diagnostic endoscopic imaging technology to image early stages of pancreatobiliary disease.
Biliary Tract↗
New polyacrylamide gel-based methods of sample preparation for optical microscopy: immobilization of DNA molecules for optical mapping.
New methods have been developed for rapid immobilization of biological macromolecules and other microscopic objects from aqueous solution at gel/gel, gel/solid and gel/solution interfaces using thin polyacrylamide gels covalently bound to glass surfaces. When quickly spread over a dry gel, an aqueous sample loses most of its water and low-molecular-weight solutes due to migration of these components into the gel. All optically observable objects thus become concentrated at the gel surface and may be easily located by light microscopy. Based on this, a procedure for binding DNA at a positively charged gel/solution interface was developed. A mild immobilization of the DNA molecules was obtained, allowing 'all in focus' observations of DNA digestion by restriction endonucleases with an apparent rate close to that in solution.
Acrylamides↗
Magneto-optical contrast in near-field optics.
We propose a simple calculation of near-field magneto-optical (MO) images based on the beam propagation method. We calculate both Faraday rotation and circular dichroism contrasts of planar magnetic structures such as as-grown thin films and ion-irradiated samples. High-contrast near-field MO images are obtained, in good agreement with our experimental observations.
Journal Article↗
Characterization of reflection scanning near-field optical microscopy and scanning tunnelling optical microscopy/photon scanning tunnelling microscopy working in preliminary approach constant height scanning mode.
The resolution in near-field images is currently determined by the visual inspection of recorded images. One of the major questions in near-field optical microscopy is 'what resolution can be reached, the tip-to-sample distance being known?' This knowledge is critical when choosing the scanning step and the distance between the tip and the sample, in a preliminary scan. This preliminary scan is often the only way to detect the interesting parts of the sample, with limited risk of tip crash and topographical artefacts. The method proposed here needs two scans of the same area, of the same sample, in constant height mode, recorded at two tip-to-sample distances. The pseudotransfer function is the ratio of the Fourier transform of these two data maps. This function enables the evaluation of the limit of resolution. Theoretical considerations are introduced to assess the method.
Journal Article↗
Pulsed photothermal radiometry in optically transparent media containing discrete optical absorbers.
A description of heat transport by conduction and radiation in inhomogeneous materials following absorption of a brief optical pulse is presented, and investigated experimentally using pulsed photothermal radiometry (PPTR). The model indicates that the role of radiation as an intramedium heat transfer modality increases with increasing temperatures and decreasing infrared (IR) absorption of the medium. However, for the range of conditions analysed in this study, conductive transfer dominates. Thus, the inclusion of radiation does not significantly perturb the internal temperature profiles, although it does influence the radiometric emission from the sample, and hence the PPTR signal. The thermal confinement effects described in this study may be relevant in photomedicine, for example in pulsed laser irradiation of tissues containing small absorbing targets.
Algorithms↗
Radiation dose distributions in three dimensions from tomographic optical density scanning of polymer gels: II. Optical properties of the BANG polymer gel.
A newly developed method of radiation dosimetry makes use of the optical properties of polymer gels. The dose-response mechanism relies on the production of light-scattering polymer micro-particles in the gel at each site of radiation absorption. The scattering produces an attenuation of transmitted light intensity that is directly related to the dose and independent of dose rate. For the BANG polymer gel (bis, acrylamide, nitrogen, and gelatin) the shape of the dose-response curve depends on the fraction of the cross-linking monomer in the initial mixture and on the wavelength of light. At 500 nm the attenuation coefficient (mu) increases by approximately 0.7 mm-1 when the dose increases from 0 to 5 Gy. The refractive index of an irradiated gel shows no significant dispersion in the visible region and depends only slightly on the dose. Turbidity difference spectra are compared with theoretical spectra of efficiency factors for total scattering, derived using Mie-Debye theory, and the average sizes of the cross-linked particles produced by radiation, as a function of dose, are established. The particle sizes increase with dose and reach approximately the wavelength of red light. The dependence of the particle sizes on cross-linker fraction parallels a similar dependence of the water proton NMR transverse relaxation rate dose response.
Acrylamide↗