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At least 235 records · Page 13Linked to original sources
PubMed1995

Optical properties of human articular tissue as implication for a selective laser application in arthroscopic surgery.

BACKGROUND AND OBJECTIVE: Optical density of normal and pathological hyaline cartilage, meniscus, and synovium is determined using native and laser-irradiated tissue samples in order to examine potentials for a selective laser ablation. STUDY DESIGN/MATERIALS AND METHODS: One hundred forty-four autopsy specimens were irradiated in a direct contact mode using a XeCl excimer laser (lambda = 308 nm; 20 ns; 40 Hz; 40 +/- 2.1 J/mm2; 800 microns fused silica fiber) and a continuous-wave Nd:YAG laser (lambda = 1,064 nm; 1 s; 124 +/- 5.4 W/mm2; 600 microns fused silica fiber). Transmission spectra were obtained by microspectrophotometry in a spectral range from 250 to 770 nm. RESULTS: In the ultraviolet spectrum analyzed, optical density (OD) is calculated to 0.81 +/- 0.05 for native hyaline cartilage, to 1.0 +/- 0.07 for meniscal tissue, and to 0.68 +/- 0.04 for synovium. With increasing wavelength the OD steadily decreases reaching mean values of 0.06 +/- 0.01, 0.13 +/- 0.03, and 0.15 +/- 0.04 at 750 nm. Compared to normal tissue degeneration of cartilage and meniscus lead to a significant increase in OD with a maximum relative OD of 4.39 and 1.26, respectively (P < .001 and P < .01). In synovitis the OD increases with a maximum ratio of 1.45:1 (P < .01). Following Nd:YAG laser exposition the OD of the coagulated zone exceeded the value of native tissue by a factor of 9.71 for cartilage, 4.71 for meniscus, and 3.04 for synovium (P < .001). Excimer irradiation leads to a 3.38-fold increase in OD for cartilage, 2.23-fold for meniscal tissue, and 1.6-fold for synovium (P < .01). CONCLUSION: The results presented indicate that a preferential ablation of pathological tissue structures in articular surgery is possible by selecting laser systems with an appropriate spectral emission range. However, thermal laser tissue interaction may lead to severe alterations in optical properties reducing potentials of a preferential or selective laser application.

Adult↗
PubMed1995

Quantitation of insulin stores in Langerhans islets by combined immunohistochemistry and computerized microspectrophotometric analysis.

Histology, size, and insulin content of Langerhans islets from normal and recent experimental hyperthyroid (REH) dogs were studied. Insulin localization in the islets was revealed by immunohistochemistry, and the remaining two variables were analyzed by computerized microspectrophotometry according to an original technique described here. Observed under the light microscope, the REH dog pancreas section shows larger than normal islets whose scarce beta-granules are mainly located near B-cell borders and grouped along capillaries. The brown areas occupied by insulin in Langerhans islets from REH and normal dogs (mean +/- SEM) are 5182 +/- 311 and 4236 +/- 287 microns2, the total mean insulin amount per respective islet section-as expressed in absorbance arbitrary units-is 1108 and 1846, and the light absorbances per such area units are 0.214 +/- 0.070 and 0.436 +/- 0.060, respectively. Measuring these variables in dog and human (large) pancreases by the conventional methods successfully used for small pancreases would have been technically impossible.

Animals↗
PubMed1991

DNA ploidy pattern of flat adenomas of the large bowel.

In an attempt to clarify the nature of "flat adenomas," DNA content was measured by means of microspectrophotometry. Thirty-nine flat adenomas (FA), 13 with mild, 22 with moderate, and 4 with severe atypia, were collected for this study. In FA, diploidy (D), polyploidy (P), and aneuploidy (A) were found 100, 0, and 0 percent in mild atypia, 41.9, 4.5, and 54.5 percent in moderate atypia, and 0, 0, and 100 percent in severe atypia, respectively. It is assumed that FA have a much higher malignancy potential than previously expected since, histologically, benign-appearing FA with moderate atypia have already contained malignant DNA patterns. In particular, those more than 5 mm in diameter show aneuploidy in 80 percent. These data suggest that FA with moderate atypia play an important role in the pathogenesis of small colonic carcinomas.

Adenoma↗
PubMed1997

Microspectrophotometric evaluation of digestibility of pollen grains.

Digestibility of pollen grains of poppy (Papaver rhoeas) and hazelnut (Corylus avellana) subjected to a human-like in vitro digestion with pancreatic enzymes was evaluated. Pollens showed different types of walls. Digestibility was determined for total protein and insoluble carbohydrate contents by means of a new application of microspectrophotometry. Results demonstrated that pollen grains of both species were only partly digested; after 24 h treatment, only 26% of carbohydrates and 48% of proteins were digested in poppy and only 3% and 59% in hazelnut. This is probably due to the difficulty of enzymes to penetrate the intine of pollen grains. The degree of digestion of insoluble carbohydrates varied in the studied species according to their chemical nature and their storage sites.

Carbohydrate Metabolism↗
PubMed1991

A microspectrophotometric study of DNA ploidy patterns of colorectal adenomas.

Eighty-four adenomas (31 mild, 25 moderate, 28 severe atypia), 32 invasive carcinomas and 15 samples of normal mucosa were collected form polypectomy and surgically resected specimens, and their DNA ploidy patterns were examined by microspectrophotometry. The frequency of polyploidy and aneuploidy were 7% and 0% in normal mucosa, 13% and 0% in mild atypia, 20% and 44% in moderate atypia, 32% and 22% in severe atypia and 31% and 53% in invasive carcinomas, respectively. Furthermore, these abnormal ploidy patterns were found frequently in moderate atypia accompanying severe atypia and mild atypia accompanying moderate atypia. These findings suggest that adenomas with moderate atypia might be the early stage of histologically overt cancer. The thin-section method (4 microns or 7 microns) was useful for measuring regional DNA ploidy patterns of colorectal adenoma.

Adenoma↗
PubMed2004

Temporal shifts in visual pigment absorbance in the retina of Pacific salmon.

The visual pigments and photoreceptor types in the retinas of three species of Pacific salmon (coho, chum, and chinook) were examined using microspectrophotometry and histological sections for light microscopy. All three species had four cone visual pigments with maximum absorbance in the UV (lambda(max): 357-382 nm), blue (lambda(max): 431-446 nm), green (lambda(max): 490-553 nm) and red (lambda(max): 548-607 nm) parts of the spectrum, and a rod visual pigment with lambda(max): 504-531 nm. The youngest fish (yolk-sac alevins) did not have blue visual pigment, but only UV pigment in the single cones. Older juveniles (smolts) had predominantly single cones with blue visual pigment. Coho and chinook smolts (>1 year old) switched from a vitamin A1- to a vitamin A2-dominated retina during the spring, while the retina of chum smolts and that of the younger alevin-to-parr coho did not. Adult spawners caught during the Fall had vitamin A2-dominated retinas. The central retina of all species had three types of double cones (large, medium and small). The small double cones were situated toward the ventral retina and had lower red visual pigment lambda(max) than that of medium and large double cones, which were found more dorsally. Temperature affected visual pigment lambda(max) during smoltification.

Aging↗
PubMed2005

Photoreceptors and visual pigments in the retina of the fully anadromous green sturgeon (Acipenser medirostrus) and the potamodromous pallid sturgeon (Scaphirhynchus albus).

Green sturgeon and pallid sturgeon photoreceptors were studied with scanning electron microscopy (SEM), microspectrophotometry and, in the case of the green sturgeon, retinal whole-mounts. The retinas of both species contain both rods and cones: cones comprise between 23% (whole-mount) and 36% (SEM) of the photoreceptors. The cone population of both species is dominated by large single cones, but a rare small single cone is also present. In both species, most rods have long outer segments of large diameter. A rod with a relatively thin outer segment is present in the pallid sturgeon retina. Mean cone packing density for the entire green sturgeon retina is 4,690+/-891 cones/mm2, with the dorsal retina 14% more dense than the ventral. There is evidence for a horizontal visual streak just above and including the optic disc. Mean rod packing density is 16,006+/-1,668 rods/mm2 for the entire retina, and fairly uniform throughout. Both species have rods with peak absorbance near 540 nm, as well as short-wavelength-sensitive cones (green: 464.5+/-0.7 nm; pallid: 439.7+/-3.5 nm); middle-wavelength-sensitive cones (green: 538.0+/-1.4 nm; pallid: 537.0+/-1.7 nm); and long-wavelength-sensitive cones (green: 613.9+/-3.0 nm; pallid: 617.8+/-7.6 nm).

Animals↗
PubMed2005

Seasonal cycle in vitamin A1/A2-based visual pigment composition during the life history of coho salmon (Oncorhynchus kisutch).

Microspectrophotometry of rod photoreceptors was used to follow variations in visual pigment vitamin A1/A2 ratio at various life history stages in coho salmon. Coho parr shifted their A1/A2 ratio seasonally with A2 increasing during winter and decreasing in summer. The cyclical pattern was statistically examined by a least-squares cosine model, fit to the 12-month data sets collected from different populations. A1/A2 ratio varied with temperature and day length. In 1+ (>12 month old) parr the A2 to A1 shift in spring coincided with smoltification, a metamorphic transition preceding seaward migration in salmonids. The coincidence of the shift from A2 to A1 with both the spring increase in temperature and day length, and with the timing of seaward migration presented a challenge for interpretation. Our data show a shift in A1/A2 ratio correlated with season, in both 0+ (<12 months old) coho parr that remained in fresh water for another year and in oceanic juvenile coho. These findings support the hypothesis that the A1/A2 pigment pair system in coho is an adaptation to seasonal variations in environmental variables rather than to a change associated with migration or metamorphosis.

Animals↗
PubMed2006

Colour vision and visual ecology of the blue-spotted maskray, Dasyatis kuhlii Müller & Henle, 1814.

Relatively little is known about the physical structure and ecological adaptations of elasmobranch sensory systems. In particular, elasmobranch vision has been poorly studied compared to the other senses. Virtually nothing is known about whether elasmobranchs possess multiple cone types, and therefore the potential for colour vision, or how the spectral tuning of their visual pigments is adapted to their different lifestyles. In this study, we measured the spectral absorption of the rod and cone visual pigments of the blue-spotted maskray, Dasyatis kuhlii, using microspectrophotometry. D. kuhlii possesses a rod visual pigment with a wavelength of maximum absorbance (lambda(max)) at 497 nm and three spectrally distinct cone types with lambda(max) values at 476, 498 and 552 nm. Measurements of the spectral transmittance of the ocular media reveal that wavelengths below 380 nm do not reach the retina, indicating that D. kuhlii is relatively insensitive to ultraviolet radiation. Topographic analysis of retinal ganglion cell distribution reveals an area of increased neuronal density in the dorsal retina. Based on peak cell densities and using measurements of lens focal length made using laser ray tracing and sections of frozen eyes, the estimated spatial resolving power of D. kuhlii is 4.10 cycles per degree.

Animals↗
PubMed1997

The photoreceptors and visual pigments of the garter snake (Thamnophis sirtalis): a microspectrophotometric, scanning electron microscopic and immunocytochemical study.

Scanning electron microscopy, immunocytochemistry, and single cell microspectrophotometry were employed to characterize the photoreceptors and visual pigments in the retina of the garter snake, Thamnophis sirtalis. The photoreceptor population was found to be comprised entirely of cones, of which four distinct types were identified. About 45.5% of the photoreceptors are double cones consisting of a large principal member joined near the outer segment with a much smaller accessory member. About 40% of the photoreceptors are large single cones, and about 14.5% are small single cones forming two subtypes. The outer segments of the large single cones and both the principal and accessory members of the doubles contain the same visual pigment, one with peak absorbance near 554 nm. The small single cones contain either a visual pigment with peak absorbance near 482 nm or one with peak absorbance near 360 nm. Two classes of small single cones could be distinguished also by immunocytochemistry and scanning electron microscopy. The small single cones with the 360-nm pigment provide the garter snake with selective sensitivity to light in the near ultraviolet region of the spectrum. This ultraviolet sensitivity might be important in localization of pheromone trails.

Animals↗
PubMed1990

The visual pigment basis for cone polymorphism in the guppy, Poecilia reticulata.

Long-wavelength visual pigment polymorphism, similar to that found in primates, was found in the guppy using microspectrophotometry (MSP). Guppies have a rod pigment with a wavelength of maximal absorbance (lambda max) at 501 nm and cone pigments with peak absorbance at 408 and 464 nm. In addition individuals may have one, two or three cone classes in the yellow-green region of the spectrum with mean lambda max values of 533, 543 and 572 nm. Unlike primates this variation is not sex-linked and may be based on only two visual pigments which occur either on their own in outer-segments of the 533 nm and 572 nm cone classes or as a mixture in the 543 nm cone class.

Animals↗
PubMed1991

A new template for rhodopsin (vitamin A1 based) visual pigments.

A new template curve for rhodopsin visual pigments is presented. The template was constructed from absorbance spectra of purified bovine rhodopsin with an abscissa transform of lambda max/lambda. Absorbance curves generated from the template are compared with absorbance spectra of visual pigments measured in situ in single cells by microspectrophotometry (msp). The template was found to agree well with msp data which included visual pigments with lambda max values ranging from 450 to 570 nm. A cubic polynomial is given by which the new template may be fitted to the long wavelength limb of visual pigment data. A Chebyshev polynomial is also given which models the new template with a high degree of accuracy. This polynomial provides a convenient method for the computer generation of visual pigment absorbance curves.

Animals↗
PubMed1991

Ultraviolet-sensitive cones in the goldfish.

Goldfish have been shown behaviourally to have ultraviolet sensitivity. We have now identified by microspectrophotometry a population of small single cones in the goldfish retina that contain a visual pigment maximally sensitive around 355-360 nm.

Animals↗
PubMed1991

Spectral characteristics of photoreceptors and horizontal cells in the retina of the Siberian sturgeon Acipenser baeri Brandt.

In the retina of Siberian sturgeon, three spectral classes of photoreceptors were identified by microspectrophotometry. These were rods, oil drop-containing and oil drop-free cones possessing P549, and oil drop-containing cones possessing P613 and P465. With intracellular recordings, rod-driven, cone-driven, and mixed horizontal cells of luminosity type were found, as well as color-opponent horizontal cells of, at least, 6 kinds. Biphasic R/G cells received hyperpolarizing input either from rods or from green cones; in R/B cells, it was from blue cones. Other three types comprised biphasic G/B (or Y/B), RG/B, and triphasic G/BR cells. So the Chondrostean retina has the color-processing circuitry common for all ray-finned fishes.

Action Potentials↗
PubMed1992

The eyespot of Chlamydomonas reinhardtii: a comparative microspectrophotometric study.

The eyespot of Chlamydomonas reinhardtii is believed to utilize a rhodopsin-like pigment in its responses to light. This paper examines its eyespot by means of microspectrophotometry with the finding of an absorption spectrum with two bands, an A-band in the blue, and a B-band in the green. This spectrum is identical to that previously recorded from the eyespot of Euglena gracilis. As with Euglena the B-band was found to have dichroic character and its spectrum was similar to the absorption curve of rhodopsin. This A-B-spectrum was always recorded from a single granule in each cell. It is concluded that both E. gracilis and C. reinhardtii may utilize a rhodopsin-like pigment as the photopigment associated with the eyespot response to light. In both these algae a few particles in each cell were found whose spectra consisted of two other bands, C and D, blue- and red-shifted, respectively, relative to the eyespot A-B-bands. There is some reason to believe that the C-D-granules may also be involved in certain light-controlled activities of the cells.

Animals↗
PubMedDate not supplied

Visual pigments and oil droplets in genetically manipulated and carotenoid deprived quail: a microspectrophotometric study.

The spectral absorbances of visual pigments and retinal oil droplets were studied in three groups of Japanese quail (Coturnix coturnix japonica): an unselected control population and two artificially selected strains that exhibited different early approach preferences between blue and red stimuli. The oil droplets were examined with and without prior carotenoid deprivation. Four cone pigments and five oil droplet types were identified, resembling those in other avian species. Carotenoid deprivation eliminated all pigmentation detectable in oil droplets by microspectrophotometry. Placement of chicks on normal diet gradually reintroduced normal pigmentation within the span of about a week. No statistically significant differences were found between normal and genetically selected birds in either visual pigments or oil droplet types, or in their relative proportions. It is concluded that differences in the early colour preferences of quail are unlikely to be a result of variation in the spectral properties of their photoreceptors.

Animals↗
PubMed1994

Visual pigments and the photic environment: the cottoid fish of Lake Baikal.

The endemic cottoid fish of Lake Baikal in Eastern Siberia offer a singular opportunity for examining within a number of closely related species, the relationships of visual pigments, photoreceptor complements and depth within a deep freshwater environment. The lake, the deepest (1600 m) and one of the largest and most ancient in the world, is unique in that the oxygen levels at the bottom are only reduced to about 80% of the surface levels. We have studied, by light microscopy, microspectrophotometry and visual pigment extraction, the retinas from 17 species of Baikal cottoids that live at different depths within the lake. Generally the retinas contain, in addition to rods, large green-sensitive double cones and small blue-sensitive single cones: surprisingly for freshwater fish, the visual pigments are based on Vitamin A1. The lambda max of both rods and cones are displaced to shorter wavelengths with increasing depth. Surface species have cones with lambda max at about 546, 525 and 450 nm and rods at 523 nm, deeper living species retain cones, but with lambda max shifting towards 500 and 425 nm and with rods at 480 nm, whereas the deepest living fish possess only rods (lambda max 480-500 nm). These data clearly show a correlation between photoreceptor complement, visual pigment lambda max and depth, but question the hypothesis that there is a correlation of pigment lambda max with water colour since, in contrast to oceanic waters, the maximum transmission of Baikal water is between 550 and 600 nm.

Animals↗
PubMed1994

Spectral characteristics of visual pigments in rainbow trout (Oncorhynchus mykiss).

We investigated retina preparations of young rainbow trout (Oncorhynchus mykiss) with body wt 5-40 g. Rods, single and double cones were measured in side-on orientation by microspectrophotometry, identifying five spectrally distinct visual pigments (or photoreceptors containing mixtures of visual pigments). The mean wavelength of peak absorbance (lambda max) of the alpha-bands were 365 and 434 nm in single cones, 531 and 576 nm in double cones, and 521 nm in the rods. The half-band width (HBW) of the main absorption bands were broader than expected of retinal- (vitamin A1-) based visual pigments, and thus, they were indicative of a mixed chromophore pool derived from both the vitamin A1 and A2 forms. One consequence of the utilization of mixed chromophores is the broadening of the alpha-band absorption in each pigment type. And yet, we obtained exceptionally narrow HBW for the UV-type pigment, when compared with HBW values expected on the basis of the linear trend seen in visual pigments absorbing in the visible spectrum. We conclude that the UV pigment in rainbow trout has an unusually narrow HBW. Nevertheless, this species is not exceptional in this regard, for the UV-absorbing visual pigments in other vertebrate species also have narrow HBW.

Animals↗