PubMed Health⌕ Search

SEARCH · PubMed Health

Results for “Microscopy, Polarization”

Explore indexed PubMed citations for clinical trials, systematic reviews and public health research. Read source abstracts and follow each citation to its original PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 145 records · Page 8Linked to original sources
PubMed1996

Polarized microscopy study of an antennal sensillum of Triatoma infestans: an ordered distribution of chitin fibrils and associated components.

Aspects of the molecular organization of the antennal sensilla trichodea of Triatoma infestans have been investigated with the use of both polarization and scanning electron microscopy. The sensilla have a smooth surface with minute bulbs on the tapered end. They showed strong positive birefringence, irrespective of the refractive index of the imbibing medium. The plotting of a form birefringence (FB) curve for native material showed slight increases in the retardation values with increases of the refractive index and at least 2 inflection points. On the other hand, a FB curve constructed for alkali-treated structures reveals higher values for the form birefringence and slight decreases in retardation values with raising refractive index. These results demonstrate that chitin fibrils are preferentially aligned with the sensilla long axis. Interestingly, the alkali treatment introduced no alterations in the retardation values measured at n = 1,435, which corresponds to the intrinsic birefringence of chitin. It is suggested that components removed by alkali-treatment have electronic transitions disposed perpendicularly to the chitin filaments and that the ill definition of the form birefringence curve of chitin is associated with the incomplete removal of chitin-associated components, which keep chitin fibrils apart from but strongly bound to each other. In addition, it is apparent from the results that cross-linking in a system with a parallel array of the chitin fibrils occurs predominantly perpendicular to the chitin fibrils.

Animals↗
PubMed1989

Direct observation of large chiral domains in chloroplast thylakoid membranes by differential polarization microscopy.

Long-range chiral organization of the pigment-protein complexes in mature granal chloroplasts has been established by differential polarization imaging and local circular dichroism spectra. Linear and circular dichroism images of oriented chloroplasts were obtained in a confocal differential polarization microscope. The circular dichroism images display signals of opposite signs emerging from discrete regions with local dichroic values much larger than anticipated, indicating domains in the thylakoid membranes having long-range chiral organization. These domains are associated with positive and negative circular dichroism bands obtained at specific locations on the chloroplasts. Surprisingly, the local circular dichroism spectra do not display the excitonic shape of spectra obtained for macroscopic suspensions, but the latter can be produced by superposition of two local spectra of opposite sign. These data are evidence for the existence of long-range chiral order of the pigment-protein complexes in thylakoid membranes. The possible role of the long-range chiral domains in the efficiency of energy delocalization through the thylakoid membranes is discussed.

Chloroplasts↗
PubMed1995

Intestinal anastomosis healing in rat: collagen concentration and histochemical characterization by Picrosirius red staining and polarizing microscopy.

The study was designed to characterize collagen fibers in the healing intestinal anastomosis of rat by examining collagen concentration and recording the polarization colors of the collagen fibers in Picrosirius red-stained tissue sections. No significant changes in collagen concentration expressed by hydroxyproline content were noted at the anastomotic site at various postoperative time points. In the normal intestine, the predominant polarization colors were in the yellow to yellow-orange range, signifying tightly packed, matured collagen. During the first postoperative week, collagen fibers at the anastomotic region exhibited mainly polarization colors in the green to green-yellow range, implying less packed intermediate collagen fibers. After 2 weeks, collagen fibers at the anastomotic region gradually reacquired their preoperative polarizing texture. These findings strongly suggest that the "quality" rather than the quantity of collagen fibers plays an important role in maintaining the tensile strength of the healing intestinal anastomosis.

Anastomosis, Surgical↗
PubMed1990

[Estimation of the healing process of denatured orthotopic bone implants in an animal model. I. Measurements with polarization microscopy].

The paper gives in a series of 3 parts a survey, quantitative statements and conclusions on the healing process of denatured orthotopic osteoresections with the initial bone obtained by, polarization optical measurements (this first part), morphological evaluation method (part II), (in these cases the collagen polymorphism served as indicator for the regeneration course) and, semiquantitative method of observation after conventionally histological treatment as well (part III). The investigations were carried out on the mandible of pigs depending on the treatment of the resected bone parts (chemical or hyperthermal denaturation in comparison with the native state). Samples of osteoreimplantions were taken in intervals of one week up to the 70th postoperative day. Histological sections were used from the different regions (contact region, gap region, border and internal regions of the resections) and investigated by the methods mentioned above. The results of the first part (polarization microscopical measurements) revealed the regular course of differentiation in the bone regeneration process: The resection is fully integrated into the initial bone after a mean duration of 112 +/- 25 days. The fastest regeneration takes place in the contact region, the slowest is found within the resection (in the case of chemical denaturation investigated).

Animals↗
PubMed1994

Polarization microscopy of picrosirius red stained sections: a useful method for qualitative evaluation of intestinal wall collagen.

Collagen pattern in healing anastomosis of intestinal wall was compared with its normal pattern in the submucosal layer. Polarization colours were recorded for thin (0.8 micron or less) and thick (1.6-2.4 micron) collagen fibres. The polarization colours of thick collagen fibres in the anastomotic site were more greenish-yellow and yellow than those in normal intestine which were more yellowish-orange and orange. These findings indicate that the collagen in the anastomotic site 4 days after operation is less packed than the collagen of normal rat intestine. Examination of the polarization colours of Picrosirius red-stained sections is a useful procedure to follow healing of anastomotic sites or diagnosis of collagen pathology in different pathologic conditions in the intestinal wall.

Anastomosis, Surgical↗
PubMed1979

A critical re-evaluation of the anisotropic index used in polarization microscopy: a study on epiphyseal cartilage.

Topo-optical reactions specific for collagen and glycosaminoglycans were performed on epiphyseal cartilage plates which differed in age, in chemical composition, and in structure. Retardation values were measured with the polarization microscope and anisotropic index values were calculated after each reaction. It was found that the anisotropic index proposed earlier for quantitative evaluation of topo-optical reactions did not refer either to the submicroscopic orientation pattern or to the quantity of cartilage matrix components. It is suggested that retardation values of induced birefringence may be only used to characterize the spatial orientation of these components in the cartilage matrix.

Aging↗
PubMed2003

[Polarization microscopy in diagnosis of metabolic disorders].

An early diagnostics of metabolism disorders by using different methods is still acute. In this respect, the crytstal-optic examination of the metabolism structures of blood serum, implemented in a polarized light (microscope MIN-8) is in the focus of attention. We studied the structure of blood serum of 160 patients with various metabolic disorders. The examinations were made through drying up, under control, the blood serum drops between two isotropic plates, the mentioned preparations were subsequently kept in the open air and examined under the microscope in polarized light. Simultaneously, the below substances were identified in the blood serum: oxalic acid, creatinines, total calcium, glycine, uric acid and cholesterol. In accordance with metabolic disorders, crystals were isolated, which characterize a type of a metabolic disorder. Thus, the fan-type dendrites are indicative of hyperoxaluria, druses and dendrite-like spherulites--hypercreatinemia; oolite spherulities are indicative of hypercalcemia, fine-grained particles are typical for hyperglycinemia, feather-like rays are typical for hyperuricemia and cross-like spherulites are typical of hypercholesterolemia. The suggested method improves the control over a type of metabolic disorder, and it can be used in the express diagnostics of a pre-pathology and pathology of metabolism.

Adult↗
PubMed1993

Polarization microscopy of picrosirius red-stained collagen from oxodipine-induced hyperplastic gingiva of beagle dogs.

Using the model of oxodipine-induced gingival hyperplasia in beagle dogs, we investigated the collagen fibres of the hyperplastic gingiva by measuring the polarization colours from Picrosirius-red stained sections. The predominant polarization colours of the thick collagen fibres (1.6-2.4 microns diameter) of male oxodipine-treated dogs were greenish-yellow to yellow, while in controls and in female oxodipine-treated dogs, the same size fibres mostly appeared orange and red. These differences may be indicative of gender variation in the genesis of hyperplastic gingiva in calcium channel blocker treated dogs.

Animals↗
PubMed1981

An argyrophil III method for the demonstration of smooth muscle cells in light and polarization microscopy.

An esterification with n-butyl alcohol containing 0.5% sulphuric acid (at 56 degrees C, for 16 hours) followed by a treatment in a special physical developer renders smooth muscle cells as well as other contractile elements (striated muscle, cilia, flagella, myoepithel cells) visible in light microscope and birefringent in polarization microscope. A few kinds of non-contractile tissue components without oriented fibrillary structure also stain but do not display birefringence.

Animals↗
PubMed1997

[Polarizing microscopy of crystalline drugs based on the crystal habit determination for the purpose of a rapid estimation of crystal habits, particle sizes and specific surface areas of small crystals].

In 1939 the author reported the results of measured refractive indices of about a hundred crystalline drugs listed in [JP V] at the Takeda Research Laboratory using a Leitz PM polarizing microscope and newly developed immersion oils. When the author had reopened the study of crystalline drugs using a polarizing microscope at the Kobe-Gakuin University starting from 1975 one of the main purposes was to clarify the relation between crystal habits and refractive indices. It had been found that in most cases of crystal habits refractive indices were uniquely measured from a predominant pair of faces forming superior the habit, and they were called as "key refractive indices". The author and his co-workers tried to investigate the possibility of measuring the key refractive indices widely from all the obtainable crystalline drugs listed in the [JP X] or [JP XI], co-operating with the Pharmacy of Kobe University Hospital. Thus, more than 170 kinds of crystalline drugs were tested for their key refractive indices and found that they were measured from about 60-70% of tested drugs. It was also clarified that the difference of 2 key refractive indices, (n2 - n1), the birefringence of the section, was also an unique invariable number for the habit, and it played an important role not only for the graphic representation of log(n2 - n1), abscissa, against (n1, n2), ordinate, for the sake of an analytical purpose but also to measure a thickness of a section (habit) using a retardation color. Then, it had been cleared that the similarity of crystal habits in the microscopic field was based on the facts of measuring the same key refractive indices, and the author had developed a chart for measuring key refractive indices as well as producing a 3 dimensional orthographic projection of a crystal habit simultaneously applying a thickness measuring method using a birefringence. Finally 3 dimensional parameter a, b, c of a crystal habit and "habit coefficients" T: square root of ab/c and L: b/c were determined from the orthographic projection. In conclusion using the similarity in crystal habits the distributions of particle sizes and specific surface areas of all the crystals in the microscopic field had been calculated by a personal computer putting in necessary habit coefficients and obtained data of parameter b. The relation between 2 dispersions of particle sizes in log (V) and specific surface areas in log (SSA) were shown under the rectangular coordinates log (V) on the abscissa and log (SSA) on the ordinate, where the loci of log (SSA) formed simple striped pattern composed of parallel straight lines depending on habit coefficients. It would be possible to estimate the value of a specific surface area of any crystalline substance by plotting the value of log (V) on the straight line of a locus of log (SSA) having the same habit coefficients.

Biological Availability↗
PubMed1990

[Tablet residues in gastrointestinal contents? A polarization microscopy screening method for rapid evaluation at the autopsy table].

When tablet residues are found in the gastrointestinal tract during autopsy, this does not only indicate the possible presence of intoxication, but may also provide indications with the regard to the kind of intoxication (e.g. suicide) if the amount of tablets is considered. If tablets have already dissolved and thus large portions can no longer be detected with the naked eye, a definitive appraisal with regard to the presence of tablet residues is often difficult or even impossible on the autopsy table. A polarization microscopic screening method is described which enables identification of characteristic tablet auxiliary substances (maize starch, sodium carboxymethyl starch, microcristalline cellulose or sodium carboxymethyl cellulose) to be identified immediately and simply in the gastrointestinal contents. It also enables a rapid orientative screening for tablet residues in glasses found or the fluid these contained as well as in aspirated material and vomit. If the active agent of the tablet can be detected by chemical toxicology, the polarization microscopic diagnosis of abundant tablet auxiliary substances is compatible with intake of large amounts of drugs, which makes self-administration highly probable.

Drug Overdose↗
PubMed1996

The orientation of eosin-5-maleimide on human erythrocyte band 3 measured by fluorescence polarization microscopy.

The dominant motional mode for membrane proteins is uniaxial rotational diffusion about the membrane normal axis, and investigations of their rotational dynamics can yield insight into both the oligomeric state of the protein and its interactions with other proteins such as the cytoskeleton. However, results from the spectroscopic methods used to study these dynamics are dependent on the orientation of the probe relative to the axis of motion. We have employed polarized fluorescence confocal microscopy to measure the orientation of eosin-5-maleimide covalently reacted with Lys-430 of human erythrocyte band 3. Steady-state polarized fluorescence images showed distinct intensity patterns, which were fit to an orientation distribution of the eosin absorption and emission dipoles relative to the membrane normal axis. This orientation was found to be unchanged by trypsin treatment, which cleaves band 3 between the integral membrane domain and the cytoskeleton-attached domain. this result suggests that phosphorescence anisotropy changes observed after trypsin treatment are due to a rotational constraint change rather than a reorientation of eosin. By coupling time-resolved prompt fluorescence anisotropy with confocal microscopy, we calculated the expected amplitudes of the e-Dt and e-4Dt terms from the uniaxial rotational diffusion model and found that the e-4Dt term should dominate the anisotropy decay. Delayed fluorescence and phosphorescence anisotropy decays of control and trypsin-treated band 3 in ghosts, analyzed as multiple uniaxially rotating populations using the amplitudes predicted by confocal microscopy, were consistent with three motional species with uniaxial correlation times ranging from 7 microseconds to 1.4 ms.

Anion Exchange Protein 1, Erythrocyte↗
PubMed2006

What can be learned about molecular reorientation from single molecule polarization microscopy?

We have developed a general approach for the calculation of the single molecule polarization correlation function C(t), which delivers a correlation of the emission dichroisms at time 0 and t. The approach is model independent and valid for general asymmetric top molecules. The key dynamic quantities of our analysis are the even-rank orientational correlation functions, the weighted sum of which yields C(t). We have demonstrated that the use of nonorthogonal schemes for the detection of the single molecule polarization responses makes it possible to manipulate the weighting coefficients in the expansion of C(t). Thus valuable information about the orientational correlation functions of the rank higher than the second can be extracted from C(t).

Journal Article↗
PubMed1990

Phospholipid order in gel- and fluid-phase cell-size liposomes measured by digitized video fluorescence polarization microscopy.

Low-light digitized video fluorescence microscopy has been utilized to measure the steady-state polarized fluorescence from the membrane probe diphenylhexatriene (DPH) and its cationic and phosphatidylcholine derivatives 1-(4-trimethylammoniumphenyl)-6-phenyl-1,3,5-hexatriene (TMA-DPH) and 2-[3-(diphenylhexatrienyl)propanoyl]-3-palmitoyl-L-alpha-phosphati dylcholine (DPH-PC), respectively, in cell-size (10-70 microns) unilamellar vesicles composed of gel-or fluid-phase phospholipid. Using an inverted microscope with epi-illumination optics and an intensified silicon intensified target camera interfaced to a minicomputer, fluorescence images of single vesicles were obtained at emission polarizer orientations of 0 degrees, 45 degrees, 90 degrees, and 135 degrees relative to the excitation light polarization direction. Fluorescence intensity ratios F90 degrees/F0 degrees (= F perpendicular/F parallel) and F135 degrees/F45 degrees were calculated on a pixel-by-pixel basis from digitized image pairs. Theoretical expressions were derived for collected polarized fluorescence as a function of position on the membrane surface as well as the degree of lipid order, in terms of the fluorophore's maximum angular motional freedom in the bilayer (identical to theta max), using a modification of the method of D. Axelrod (1979. Biophys. J. 26:557-574) together with the "wobbling-in-a-cone" model of probe rotational diffusion. Comparison of experimental polarization ratios with theoretical ratios yielded the following results. In gel-phase dipalmitoyl-phosphatidylcholine, the data for all three probes correspond to a model in which the cone angle theta max = 17 +/- 2 degrees and there exists a collective tilt of the phospholipid acyl chains of 30 degrees relative to the bilayer normal. In addition, approximately 5% of DPH and TMA-DPH molecules are aligned parallel to the plane of the bilayer. In fluid-phase palmitoyloleoyl-phosphatidylcholine, the data are well fit by models in which theta max = 60 +/- 2 degrees for DPH and DPH-PC and 32 +/- 4 degrees for TMA-DPH, with approximately 20% of DPH molecules and 10% of TMA-DPH molecules aligned parallel to the bilayer plane, and a net phospholipid tilt at or near the headgroup region of approximately 30 degrees. The results demonstrate that lipid order can be measured with a spatial resolution of approximately 1 micron2 in cell-size vesicles even with high aperture observation through a microscope.

Birefringence↗
PubMed2004

High-contrast imaging of fluorescent protein FRET by fluorescence polarization microscopy.

Detection of Forster resonance energy transfer (FRET) between fluorescent protein labeled targets is a valuable strategy for measurement of protein-protein interactions and other intracellular processes. Despite the utility of FRET, widespread application of this technique to biological problems and high-throughput screening has been limited by low-contrast measurement strategies that rely on the detection of sensitized emission or photodestruction of the sample. Here we report a FRET detection strategy based on detecting depolarized sensitized emission. In the absence of FRET, we show that fluorescence emission from a donor fluorescent protein is highly polarized. Depolarization of fluorescence emission is observed only in the presence of energy transfer. A simple detection strategy was adapted for fluorescence microscopy using both laser scanning and wide-field approaches. This approach is able to distinguish FRET between linked and unlinked Cerulean and Venus fluorescent proteins in living cells with a larger dynamic range than other approaches.

Animals↗
PubMed2006

Laser-driven microsecond temperature cycles analyzed by fluorescence polarization microscopy.

We demonstrate a novel technique to achieve fast thermal cycles of a small sample (a few femtoliters). Modulating a continuous near-infrared laser focused on a metal film, we can drive the local temperature from 130 to 300 K and back, within a few microseconds. By fluorescence microscopy of dyes in a thin glycerol film, we record images of the hot spot, calibrate its temperature, and follow its variations in real time. The temperature dependence of fluorescence anisotropy, due to photophysics and rotational diffusion, gives a steady-state temperature calibration between 200 and 350 K. From 200 to 220 K, we monitor temperature more accurately by fluorescence autocorrelation, a probe for rotational diffusion. Time-resolved measurements of fluorescence anisotropy give heating and cooling times of a few microseconds, short enough to supercool pure water. We designed our method to repeatedly cycle a single (bio)molecule between ambient and cryostat temperatures with microsecond time resolution. Successive measurements of a structurally relevant variable will decompose a dynamical process into structural snapshots. Such temperature-cycle experiments, which combine a high time resolution with long observation times, can thus be expected to yield new insights into complex processes such as protein folding.

Diffusion↗
PubMed1996

Regional differences in molecular cross-linking of periodontal ligament collagen of rat incisor, by polarizing microscopy.

Collagen, a naturally birefringent biopolymer and key structural component of the periodontal ligament (PDL), is altered substantially with regard to its molecular cross-linked structure by the dietary lathyrogen, beta-amino-proprionitrile (beta-APN). Our purpose in studying beta-APN-fed animals was to learn if the strength of birefringence of periodontal collagen, measured microscopically by the Senarmont compensator method, correlates with the molecular changes known to occur in these lathyritic animals, and to explore this technique for the periodontal ligament. Five experimental animals were fed a diet containing 0.25% beta-APN for two weeks, and 3 control animals were fed normal rat chow. Tissues were decalcified and the mandibular incisors were cut in cross section at 4 microns and stained with eosin Y. The Senarmont compensator, an attachment for the polarizing microscope, was used to measure phase retardation. Ten measurements were taken from each of the three sides (mesial, lateral and lingual) of the triangularly shaped incisor sections. The collagen fibers of the beta-APN-fed rats had lower values of phase retardation than the controls (p < 0.001), indicating reduced molecular organization. In addition, minor but significant regional differences were revealed, supporting the method for structural studies on the periodontal collagen.

Animals↗